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1

Rolling textures in nanoscale Cu\\/Nb multilayers  

Microsoft Academic Search

Rolling textures in nanoscale multilayered thin films are found to differ markedly from textures observed in bulk materials. Multilayered thin films consisting of alternating Cu and Nb layers with columnar grains were produced by magnetron sputtering, with individual layer thickness ranging from 4 ?m to 75 nm and Cu\\/Nb interfaces locally satisfying the Kurdjumov–Sachs (K–S) orientation relations. After rolling to

Peter M. Anderson; John F. Bingert; Amit Misra; John P. Hirth

2003-01-01

2

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

3

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

E-print Network

Nanoscale Interfacial Friction and Adhesion on Supported versus Suspended Monolayer and Multilayer, we determine the e ect of tip- subsurface van der Waals interactions on nanoscale friction in pull-o force with thickness. Further, at low applied loads, friction increases with increasing number

Li, Teng

4

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 industry and as thin protective coatings. In this study, nanoindentation was performed on Ti/Au NMM, and total multilayers thicknesses of 400 nm and 1 micron were tested. A Hysitron Nanoindenter was used

Collins, Gary S.

5

Deformation-induced nanoscale mixing reactions in Cu/Ni and Ag/Pd multilayers  

SciTech Connect

During the repeated cold rolling of Cu/Ni and Ag/Pd multilayers, a solid solution forms at the interfaces as nanoscale layer structure with a composition that replicates the overall multilayer composition. The interfacial mixing behavior was investigated by means of X-ray diffraction and scanning transmission electron microscopy. During deformation induced reaction, the intermixing behavior of the Cu/Ni and Ag/Pd multilayers is in contrast to thermally activated diffusion behavior. This distinct behavior can provide new kinetic pathways and offer opportunities for microstructure control that cannot be achieved by thermal processing.

Wang, Z.; Perepezko, J. H., E-mail: perepezk@engr.wisc.edu [Department of Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Avenue, Madison, Wisconsin 53706 (United States)

2013-11-04

6

Transport-Controlling Nanoscale Multilayers for Biomedical Devices  

E-print Network

..................................................................................... 18 2.4. Conclusions ...................................................................................................... 25 3. TUNING OF BIOSENSOR RESPONSE USING MANIPULATION OF NANOFILM COATING PROPERTIES...-assembly provides a unique opportunity to realize functional systems at the micro/nanoscale. In particular, layer-by-layer (LbL) self-assembly is a technique that holds great promise for realization of biosensors due to the mild aqueous conditions, versatility...

Park, Jae Bum

2012-10-19

7

Bilayer period dependence of CrN/CrAlN nanoscale multilayer thin films  

NASA Astrophysics Data System (ADS)

CrN/CrAlN nanoscale multilayer thin films with a bilayer period ( ?) ranging from 4.4 to 44.1 nm were deposited on Si wafers (100) by closed field unbalanced magnetron sputtering (CFUBMS). The ? of the layers was controlled by the rotation speed of the substrate holder. The coatings were characterized by high resolution X-ray diffraction and field emission transmission electron microscopy. The CrN/CrAlN nanoscale multilayer thin films exhibited a CrN (200) and AlN (200) crystalline orientation. Nano-indentation testing revealed a hardness ranging from 37 to 46 GPa according to the bilayer period. The highest hardness was obtained with a bilayer period of 5.5 nm due to the high resistance to plastic deformation.

Kim, Youn J.; Byun, Tae J.; Han, Jeon G.

2009-02-01

8

Perturbation of nanoscale structure of polypeptide multilayer thin films.  

PubMed

Multilayer thin films formed by sequential deposition of oppositely charged polypeptides on a charged surface are known from previous studies to comprise a mixture of types of secondary structure. Here, study of the perturbation of polypeptide film structure by deposition of poly(allylamine hydrochloride) (PAH) and poly(styrenesulfonate) (PSS) on the film surface has revealed differences in behavior attributable to physical properties of the peptides. The methods of analysis were circular dichroism spectroscopy (CD), ultraviolet spectroscopy (UVS), and quartz crystal microbalance (QCM). Films made of poly(L-lysine) (PLL) and poly(L-glutamic acid) (PLGA) with an average charge per monomer of about 1 were substantially more susceptible to perturbation of structure than films made of designed polypeptides with an average charge per monomer of about 0.5, despite preparation under identical conditions. PLL-PLGA films showed loss or gain of material and change in secondary structure content on perturbation, whether made of high molecular mass (ca. 90 kDa) or low molecular mass (ca. 14 kDa) polymers. By contrast, films made of very low molecular mass (ca. 3.5 kDa) designed polypeptides showed little change in secondary structure content. The data suggest that the penetrability of PSS or PAH into a film and therefore film density can depend substantially on the polypeptides of which it is made and the character of intermolecular interactions. PMID:15924473

Zhang, Ling; Li, Bingyun; Zhi, Zheng-Liang; Haynie, Donald T

2005-06-01

9

In situ observation of rapid reactions in nanoscale Ni-Al multilayer foils using synchrotron radiation  

NASA Astrophysics Data System (ADS)

The observation of rapid reactions in nanoscale multilayers present challenges that require sophisticated analysis methods. We present high-resolution in situ x-ray diffraction analysis of reactions in nanoscale foils of Ni0.9V0.1-Al using the Mythen II solid-state microstrip detector system at the Material Science beamline of the Swiss Light Source Synchrotron at Paul Scherrer Institute in Villigen, Switzerland. The results reveal the temperature evolution corresponding to the rapid formation of NiAl intermetallic phase, vanadium segregation and formation of stresses during cooling, determined at high temporal (0.125 ms) and angular (0.004°) resolution over a full angular range of 120°.

Fadenberger, Konrad; Gunduz, Ibrahim Emre; Tsotsos, Chrysostomos; Kokonou, Maria; Gravani, Styliani; Brandstetter, Stefan; Bergamaschi, Anna; Schmitt, Bernd; Mayrhofer, Paul H.; Doumanidis, Charalabos C.; Rebholz, Claus

2010-10-01

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

Theory and modeling of the mechanical behavior of nanoscale and finescale multilayer thin films  

NASA Astrophysics Data System (ADS)

In this work, a 3D Dislocation Cellular Automaton (CA) model is developed and calibrated first; then the model is applied to study the mechanical properties of nanoscale and finescale multilayer thin films. In the 3D dislocation model, the study object has a FCC structure. To calibrate this model, three examples involving operation of a Frank-Read source are chosen. These examples also highlight the benefits and drawbacks of the method. A benefit to discretization is that dislocation evolution may be analyzed via spatial averaging over collections of patches, so that the discrete versus continuum nature of the results may be studied. Further, dislocation reactions and cross slip are accommodated easily and, in principle, Monte-Carlo schemes can be integrated into the evolution formalism. Overall, the discrete nature of the method is attractive for incorporating the kinetics of thermally activated states and for simplifying the range of geometries and threshold criteria associated with dislocation reactions. This 3D Dislocation Cellular Automaton model is employed to simulate yield and hardening in nanostructured metallic multilayer thin films. Threading and interfacial dislocation sources are studied. The films are composed of 2 types of alternating single crystalline FCC layers with a (001) epitaxy, a mismatch in stress-free lattice parameter, but no elastic modulus mismatch. Interfaces are assigned no additional strength except that from lattice parameter mismatch and interfacial dislocation arrays. Three regimes of tensile plastic response are identified based on the evolution of interfaces during tensile deformation. For smaller individual layer thickness, interfaces are coherent initially and remain so up to bulk yield (Regime I). For intermediate layer thickness, interfaces are coherent initially but become semi-coherent prior to bulk yield (Regime IIa). For larger layer thickness, interfaces are semi-coherent initially and acquire additional dislocation content prior to bulk yield (Regime IIb). The evolution of interfacial structure during deformation in Regimes IIa and IIb occurs due to deposition of dislocation content along interfaces by confined layer slip (CLS). The overall outcome is that the plastic strength of multilayer thin films increases with decreasing layer thickness until Regime I is encountered. Strength in Regime I may increase, reach a plateau, or even decrease. The results are consistent with experimental measurements of hardness, including the Ag/Al system in particular. (Abstract shortened by UMI.)

Li, Qizhen

12

Theoretical explanation of Ag\\/Cu and Cu\\/Ni nanoscale multilayers softening  

Microsoft Academic Search

Relationship between metallic multilayers hardness and monolayer thickness has been investigated and explained for electroplated Ag\\/Cu and Cu\\/Ni multilayers using a modified Thomas–Fermi–Dirac electron theory. Experiments reveal that the peak hardness of Ag\\/Cu multilayers occurs at the monolayer thickness of about 25nm, while the peak hardness of Cu\\/Ni multilayers occurs at about 50nm. Critical monolayer thickness corresponding to the peak

Fengzhang Ren; Shiyang Zhao; Wuhui Li; Baohong Tian; Litao Yin; Alex A. Volinsky

2011-01-01

13

Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites  

NASA Astrophysics Data System (ADS)

In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called "interphase" between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC-TiC)n interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC-TiC)n films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

Jacques, S.; Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P.

2013-06-01

14

Synthesis and characterization of titanium carbide, titanium boron carbonitride, titanium boride/titanium carbide and titanium carbide/chromium carbide multilayer coatings by reactive and ion beam assisted, electron beam-physical vapor deposition (EB-PVD)  

NASA Astrophysics Data System (ADS)

The purpose of the present work was to investigate the synthesis of titanium carbide, TiBCN, TiB2/TiC and TiC/Cr23C6 multilayer coatings by several methods of electron beam-physical vapor deposition (EB-PVD) and examine the affects of various processing parameters on the properties and microstructures of the coatings. TiC was successfully deposited by reactive ion beam assisted (RIBA), EB-PVD and the results were compared to various titanium carbide coatings deposited by a variety of techniques. The affects of substrate temperature and ion beam current density were correlated with composition, hardness, changes in the lattice parameter, degree of crystallographic texture, residual stress, surface morphology, and microstructure. The average Vicker's hardness number was found to increase with increasing ion beam current density and increase over the substrate temperature range of 250°C to 650°C. The average Vicker's hardness number decreased at a substrate temperature of 750°C as a result of texturing and microstructure. The present investigation shows that the average Vicker's hardness number is not only a function of the composition, but also the microstructure including the degree of crystallographic texture. TiB2/TiC multilayer coatings were deposited by argon ion beam assisted, EB-PVD with varying number of total layers to two different film thicknesses under slightly different deposition conditions. In both cases, the hardness of the coatings increased with increasing number of total layers. The adhesion of the coatings ranged from 30 N to 50 N, with the better adhesion values obtained with the thinner coatings. The crystallographic texture coefficients of both the TiC and TiB2 layers were found to change with increasing number of total layers. The multilayer design was found to significantly affect the microstructure and grain size of the deposited coatings. The fracture toughness was found to decrease with increasing number of total layers and was attributed to the increase in hardness and reduction in the total amount of compressive stress. TiBCN coatings were synthesized by the co-evaporation of titanium, titanium diboride, and carbon (through tungsten) while simultaneously bombarding the substrate surface with a mixture of argon and nitrogen ionized gas which has not been performed to the author's knowledge. The bulk composition was determined by EPMA and suggests that TiBCN has a wide compositional range similar to TiN and TiC. The TiBCN coatings were determined to be nano-crystalline with a cubic crystallographic structure. The average Vicker's hardness number of the TiBCN coatings ranged from 2777 VHN0.050 to 3343 VHN0.050 with the highest value reported for the higher concentrations of boron. The adhesion of the coatings to WC-6wt.Co-0.3wt.%TaC was found to increase from 20 N to 52 N with decreasing compressive stress. Lastly, multilayer titanium carbide and chromium carbide coatings with varying individual layer thickness were synthesized by the co-evaporation of Ti, Cr and C through tungsten at elevated temperatures. The average Vicker's hardness number was found to increase from 1302 VHN0.050 to 2052 VHN0.050 by changing the individual layer thickness of the multilayers. In addition, the grain size, measured compressive stress, and fracture toughness values all decreased with decreasing individual layer thickness.

Wolfe, Douglas Edward

15

Structure and mechanical properties of nanoscale multilayered CrN/ZrSiN coatings  

SciTech Connect

Nanocrystalline/amorphous CrN/ZrSiN multilayer coatings with a bilayer thickness ranging from 11 to 153 nm were prepared by reactive magnetron sputtering technique. The microstructure and mechanical properties of these thin films were characterized by x-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and nanoindentation. The formation of nanocrystalline CrN and nanocomposite ZiSiN in the single layer coatings was identified by XRD and FTIR. The periodic structure of the as-deposited multilayer coatings was confirmed by TEM observation. Nanoindentation tests showed that both the values of hardness (H) and reduced elastic modulus (E{sub r}) of CrN/ZrSiN multilayers remained almost constant despite varying the bilayer thickness. The multilayer coatings exhibited higher H of 30 GPa and higher resistance to plastic deformation when compared to the single layer CrN and ZrSiN coatings.

Zhang, Z. G.; Rapaud, O.; Allain, N.; Baraket, M.; Dong, C.; Coddet, C. [State Key Laboratory of Materials Modification, Dalian University of Technology, Dalian 116024, China and LERMPS, Universite de Technologie de Belfort-Montbeliard (UTBM), Site de Montbeliard, F-90010 Belfort Cedex (France); LERMPS, Universite de Technologie de Belfort-Montbeliard (UTBM), Site de Montbeliard, F-90010 Belfort Cedex (France); State Key Laboratory of Materials Modification, Dalian University of Technology, Dalian 116024 (China); LERMPS, Universite de Technologie de Belfort-Montbeliard (UTBM), Site de Montbeliard, F-90010 Belfort Cedex (France)

2009-07-15

16

Multilayer polypeptide nanoscale coatings incorporating IL-12 for the prevention of biomedical device-associated infections.  

PubMed

Biomedical device-associated infection is one of the most common and problematic complications faced by millions of patients worldwide. The current antibiotic therapy strategies face challenges, the most serious of which is antibiotic resistance. Studies have shown that the systemic level of interleukin 12 (IL-12) decreases following major injuries resulting in decreased cell-mediated immune response. Here we report the development of IL-12 nanoscale coatings using electrostatic layer-by-layer self-assembly nanotechnology. We found that IL-12 nanoscale coatings at the implant/tissue interface substantially decrease infections in vivo, and IL-12 nanoscale coatings are advantageous over traditional treatments. This approach could be a revolutionary step toward preventing device-associated infections using a non-antibiotic approach. PMID:19215980

Li, Bingyun; Jiang, Bingbing; Boyce, Brandon M; Lindsey, Brock A

2009-05-01

17

Multilayer polypeptide nanoscale coatings incorporating IL-12 for the prevention of biomedical device associated infections  

PubMed Central

Biomedical device-associated infection is one of the most common and problematic complications faced by millions of patients worldwide. The current antibiotic therapy strategies face challenges, the most serious of which is antibiotic resistance. Studies have shown that the systemic level of interleukin 12 (IL-12) decreases following major injuries resulting in decreased cell-mediated immune response. Here we report the development of IL-12 nanoscale coatings using electrostatic layer-by-layer self-assembly nanotechnology. We found that IL-12 nanoscale coatings at the implant/tissue interface substantially decrease infections in vivo, and IL-12 nanoscale coatings are advantageous over traditional treatments. This approach could be a revolutionary step toward preventing device-associated infections using a non-antibiotic approach. PMID:19215980

Li, Bingyun; Jiang, Bingbing; Boyce, Brandon M.; Lindsey, Brock A.

2013-01-01

18

Multilayered graphene in K(a)-band: nanoscale coating for aerospace applications.  

PubMed

We report on the experimental study of electromagnetic (EM) properties of multilayered graphene in K(a)-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 was 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, being only some thousandth of skin depth, 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, multilayer graphene emerges as a promising material for manufacturing ultrathin microwave coatings to be used in aerospace applications. PMID:23882850

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

2013-08-01

19

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

E-print Network

Keywords: Multilayer structure Hardness Mechanical properties Metals and alloys Thin films Relationship consists of the same thickness multiple monolayers. Each monolayer thickness was controlled and the pressure exerted by Fermi electrons, which supports electron shells expansion at the expense of decreasing

Volinsky, Alex A.

20

Nanoscale steel-brass multilayer laminates made by cold rolling: Microstructure and tensile properties  

SciTech Connect

The thrust of this study is to fabricate steel-brass multilayer laminates with layer thicknesses in the nanometer range and to evaluate their mechanical properties. Repeated cold rolling of multilayer stacks was adopted to produce the laminates, because the relative simplicity and the low-cost nature of this process can allow the scaling-up of the technique to the level of commercial-scale production. This work is a continuation of a previous study, in which steel-brass laminates with layer thicknesses in the micrometer range were fabricated for the first time and their tensile properties were evaluated. The present work, however, emphasizes making multilayers with layer thicknesses in the nanometer range and evaluating their mechanical properties. The dependence of strength and ductility on the layer spacing in the nanometer range, is highlighted. It is shown that strength levels comparable to quenched and tempered low alloy steels can be achieved in the laminates by rolling down to the low end of nanometer range. The relevant strengthening mechanisms are also discussed.

Kavarana, F.H.; Ravichandran, K.S.; Sahay, S.S.

2000-05-10

21

A transmission electron microscopy study of the deformation behavior underneath nanoindents in nano-scale Al-TiN multilayered composites  

SciTech Connect

Nano-scale multilayered Al-TiN composites were deposited with DC magnetron sputtering technique in two different layer thickness ratios - Al:TiN = 1:1 and Al:TiN = 9:1. The Al layer thickness varied from 2 nm to 450 nm. The hardness of the samples was tested by nanoindentation using a Berkovich tip. Cross-sectional Transmission Electron Microscopy (TEM) was carried out on samples extracted with Focused Ion Beam (FIB) from below the nanoindents. This paper presents the results of the hardness tests in the Al-TiN multilayers with the two different thickness ratios and the observations from the cross-sectional TEM studies of the regions underneath the indents. These studies showed remarkable strength in the multilayers, as well as some very interesting deformation behavior in the TiN layers at extremely small length scales, where the hard TiN layers undergo co-deformation with the Al layers.

Bhattacharyya, Dhriti [Los Alamos National Laboratory; Mara, Nathan A [Los Alamos National Laboratory; Dickerson, Patricia O [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory; Hoagland, R G [Los Alamos National Laboratory

2009-01-01

22

Mechanics of nanoscale metallic multilayers: from atomic-scale to micro-scale  

SciTech Connect

Layered composites of Cu/Nb with incoherent interfaces achieve very high strength levels. Interfaces play a crucial role in materials strength by acting as barriers to slip. Atomistic models of Cu/Nb bilayers are used to explore the origins of this resistance. The models clearly show that dislocations near an interface experience an attraction toward the interface. This attraction is caused by shear of the interface induced by the stress field of the dislocation. More importantly, atomistic simulations also reveal that interfacial dislocations easily move in interfaces by both glide and climb. Integrating these findings into a micro-scale model, we develop a three-dimensional crystal elastic-plastic model to describe the mechanical behavior of nanoscale metallic multi layers.

Wang, Jian [Los Alamos National Laboratory; Hoagland, Richard G [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory

2008-01-01

23

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

24

Hot filament chemical vapour deposition and wear resistance of diamond films on WC-Co substrates coated using PVD-arc deposition technique  

Microsoft Academic Search

Different Cr- and Ti-base films were deposited using PVD-arc deposition onto WC-Co substrates, and multilayered coatings were obtained from the superimposition of diamond coatings, deposited on the PVD interlayer using hot filament chemical vapour deposition (HFCVD). The behaviour of PVD-arc deposited CrN and CrC interlayers between diamond and WC-Co substrates was studied and compared to TiN, TiC, and Ti(C,N) interlayers.

Riccardo Polini; Fabio Pighetti Mantini; Massimiliano Barletta; Roberta Valle; Fabrizio Casadei

2006-01-01

25

Nanoscale layer-selective readout of magnetization direction from a magnetic multilayer using a spin-torque oscillator  

NASA Astrophysics Data System (ADS)

Technology for detecting the magnetization direction of nanoscale magnetic material is crucial for realizing high-density magnetic recording devices. Conventionally, a magnetoresistive device is used that changes its resistivity in accordance with the direction of the stray field from an objective magnet. However, when several magnets are near such a device, the superposition of stray fields from all the magnets acts on the sensor, preventing selective recognition of their individual magnetization directions. Here we introduce a novel readout method for detecting the magnetization direction of a nanoscale magnet by use of a spin-torque oscillator (STO). The principles behind this method are dynamic dipolar coupling between an STO and a nanoscale magnet, and detection of ferromagnetic resonance (FMR) of this coupled system from the STO signal. Because the STO couples with a specific magnet by tuning the STO oscillation frequency to match its FMR frequency, this readout method can selectively determine the magnetization direction of the magnet.

Suto, Hirofumi; Nagasawa, Tazumi; Kudo, Kiwamu; Mizushima, Koichi; Sato, Rie

2014-06-01

26

Femtosecond Single-Shot Imaging of Nanoscale Ferromagnetic Order in Co/Pd Multilayers using Resonant X-ray Holography  

SciTech Connect

We present the first single-shot images of ferromagnetic, nanoscale spin order taken with femtosecond x-ray pulses. X-ray-induced electron and spin dynamics can be outrun with pulses shorter than 80 fs in the investigated fluence regime, and no permanent aftereffects in the samples are observed below a fluence of 25 mJ/cm{sup 2}. Employing resonant spatially-muliplexed x-ray holography results in a low imaging threshold of 5 mJ/cm{sup 2}. Our results open new ways to combine ultrafast laser spectroscopy with sequential snapshot imaging on a single sample, generating a movie of excited state dynamics.

Wang, Tianhan; Zhu, Diling; Benny Wu,; Graves, Catherine; Schaffert, Stefan; Rander, Torbjorn; Muller, leonard; Vodungbo, Boris; Baumier, Cedric; Bernstein, David P.; Brauer, Bjorn; Cros, Vincent; Jong, Sanne de; Delaunay, Renaud; Fognini, Andreas; Kukreja, Roopali; Lee, Sooheyong; Lopez-Flores, Victor; Mohanty, Jyoti; Pfau, Bastian; Popescu, 5 Horia

2012-05-15

27

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

28

Ignition properties of multilayer nanoscale reactive foils and the properties of metal-ceramic joints made with the same  

NASA Astrophysics Data System (ADS)

A novel method for joining metals and ceramics using an Al-(Ni-7V) reactive multilayer foil as a heat source was studied. The components in the joint are first pre-wet or pre-metallized with a solder or braze before the reactive foil is placed between them and reacted, melting the solder or braze. On cooling, a solid joint is formed. It was shown using a SiC-Ti joint system that for a given joint system, there is are critical values for the foil's heat of reaction and total heat below which the braze in the joint will not melt, with foil heat of reaction having more of an impact than total heat. Experimental results from Al-Al and Al2O3-Al2O3 joint systems showed that the interface between the solder and the joint component can play a critical role in determining joint strength. Experimental results and numerical predictions using Al-Al2O3 and Al-glass joint systems showed that the elastic strain energy (ESE) and residual stress in a metal-ceramic reactive foil have two sources: The bending, caused by the uneven thermal profile across each joint component created by the reacting foil, that the joint components undergo while the solder or braze is molten and which is locked in when the solder or braze solidifies, and uneven average thermal contraction between the two components. The distribution of elastic strain energy and stress in a reactive foil joint is determined by the thermal diffusivities and coefficients of thermal expansion of the two joint components. The ignition requirements of reactive foils were investigated using two experimental methods, an electric pulse and mechanical stab detonation, and a numerical simulation of the electric pulse ignition method. Experimental results and numerical predictions showed that increasing foil bilayer or increasing intermixed layer thickness will make a foil more difficult to ignite. An estimated energy density of 1GJ/m3 was found experimentally to be an upper limit of the minimum energy density required for ignition of a 1:1 molar ratio Al-(Ni-7V) reactive foil with 50nm bilayers and a 2.25nm intermixed layer thickness. An autoignition temperature of approximately 419K was found using both experimental results and numerical predictions, both of which accounted for heat spreading during an ignition attempt.

Spey, Stephen John, Jr.

29

Entwicklung neuer PVD-Beschichtungen  

NASA Astrophysics Data System (ADS)

Der Leitgedanke des SFB 442 besteht in der Realisierung neuartiger umweltfreundlicher tribologischer Systeme. Bisherige tribologische Systeme werden hierbei derart modifiziert, dass die oberflächenaktiven Funktionen hochadditivierter mineralölbasierter und oftmals umweltbedenklicher Schmierstoffe auf die Werkzeug- und Bauteiloberflächen übertragen werden. Hierzu war die Entwicklung innovativer Werkstoffverbunde erforderlich, die die Aufgaben wie Verschleißschutz, Reibungsminimierung und Korrosionsschutz übernehmen können. Unter Werkstoffverbund sind in diesem Zusammenhang komplexe Systeme, bestehend aus Beschichtung und Grundwerkstoff zu verstehen, die entsprechend den auftretenden Beanspruchungen ausgelegt werden. Ein großes Potential bieten an dieser Stelle mittels PVD (Physical Vapour Deposition)-Technologien abgeschiedene Dünnschichtsysteme, da diese trotz geringer Schichtdicken (1-20 µm) beispielsweise einen hohen Verschleißschutz gewährleisten. Das geringe Aufmaß ermöglicht zudem die Beschichtung endkonturgetreuer Geometrien mit engen Form- und Maßtoleranzen, sodass mechanische Nachbehandlungen nicht mehr erforderlich sind.

Bobzin, Kirsten; Bagcivan, Nazlim; Ewering, Mara; Goebbels, Nico Andreas; Weiß, Raphael; Warnke, Carsten

30

Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings  

NASA Technical Reports Server (NTRS)

In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (< 10 microns) single layers to be deposited and multilayer coatings of less than 100 microns to be generated with the flexibility to tailor microstructures by changing processing conditions. Coatings of yttria-stabilized zirconia (YSZ) were applied to NiCrAlY bond coated superalloy substrates using the PS-PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

Harder, Bryan J.; Zhu, Dongming

2011-01-01

31

An assessment of mixed and classical theories on global and local response of multilayered orthotropic plates  

Microsoft Academic Search

This article assesses two-dimensional theories to evaluate global and local response of orthotropic, multilayered plates. The introductory discussion outlines five, relevant key-points that should be to be addressed in the modeling of multilayered structures. Classical theories formulated on the basis of Principle of Virtual Displacements (PVD) and mixed theories based on the Reissner Mixed Variational Theorem (RMVT) are presented. Theories

Erasmo Carrera

2000-01-01

32

On the influence of strain on ion transport: microstructure and ionic conductivity of nanoscale YSZ|Sc2O3 multilayers.  

PubMed

Multilayer samples of the type (YSZ|Sc2O3) × n with layer thicknesses between 8 nm (n=100) and 250 nm (n=5) were prepared on (0001) sapphire substrates by pulsed laser deposition (PLD). The samples were characterised using X-ray diffraction (XRD), scanning electron microscopy (HRSEM) and transmission electron microscopy (TEM/HRTEM, SAED (selected-area electron diffraction) and quantitative EELS (electron energy-loss spectroscopy)). The polycrystalline layers show a columnar microstructure, which is typical for the used preparation technique. The layers are highly textured and only one axial orientation relation is found between yttria-stabilised zirconia (YSZ), scandium oxide and the substrate: (0001) Al2O3?(111) Sc2O3?(111) YSZ. A preferred orientation relationship also exists for the azimuthal rotation of the crystallites, which was demonstrated by SAED, XRD pole figure measurements and fast Fourier transformation (FFT) of HRTEM micrographs. The interfaces between YSZ, Sc2O3 and the substrate are sharp and do not contain diffuse transition regions. Dislocations appear not to be arranged in regular arrays. With increasing interface density (thinner individual layers in the multilayer), the conductivity of the multilayers decreases. We relate this to the negative nominal misfit present at the YSZ|Sc2O3 interfaces (compressive stress in YSZ at the phase boundaries). This observation agrees well with the previously investigated case of YSZ|Y2O3 (A. Peters et al., Phys. Chem. Chem. Phys., 2008, 10, 4623), where tensile misfit strain was present in YSZ at the phase boundaries, leading to a conductivity increase. PMID:20938560

Schichtel, Nicole; Korte, Carsten; Hesse, Dietrich; Zakharov, Nikolai; Butz, Benjamin; Gerthsen, Dagmar; Janek, Jürgen

2010-11-21

33

Corrosion resistance and friction of sintered NdFeB coated with Ti/TiN multilayers  

E-print Network

performance. TiN is a hard physical vapor deposition (PVD) coating, widely used in wear and corrosionCorrosion resistance and friction of sintered NdFeB coated with Ti/TiN multilayers Yuanyuan Cheng Polarization Fretting corrosion Ti/TiN multilayers were deposited on sintered NdFeB by radio frequency

Volinsky, Alex A.

34

Effects of MeV Si ions bombardment on the thermoelectric generator from SiO 2/SiO 2 + Cu and SiO 2/SiO 2 + Au nanolayered multilayer films  

NASA Astrophysics Data System (ADS)

The defects and disorder in the thin films caused by MeV ions bombardment and the grain boundaries of these nanoscale clusters increase phonon scattering and increase the chance of an inelastic interaction and phonon annihilation. We prepared the thermoelectric generator devices from 100 alternating layers of SiO 2/SiO 2 + Cu multi-nano layered superlattice films at the total thickness of 382 nm and 50 alternating layers of SiO 2/SiO 2 + Au multi-nano layered superlattice films at the total thickness of 147 nm using the physical vapor deposition (PVD). Rutherford Backscattering Spectrometry (RBS) and RUMP simulation have been used to determine the stoichiometry of the elements of SiO 2, Cu and Au in the multilayer films and the thickness of the grown multi-layer films. The 5 MeV Si ions bombardments have been performed using the AAMU-Center for Irradiation of Materials (CIM) Pelletron ion beam accelerator to make quantum (nano) dots and/or quantum (quantum) clusters in the multilayered superlattice thin films to decrease the cross plane thermal conductivity, increase the cross plane Seebeck coefficient and cross plane electrical conductivity. To characterize the thermoelectric generator devices before and after Si ion bombardments we have measured Seebeck coefficient, cross-plane electrical conductivity, and thermal conductivity in the cross-plane geometry for different fluences.

Budak, S.; Chacha, J.; Smith, C.; Pugh, M.; Colon, T.; Heidary, K.; Johnson, R. B.; Ila, D.

2011-12-01

35

Iron-regulated transcription of the pvdA gene in Pseudomonas aeruginosa: effect of Fur and PvdS on promoter activity.  

PubMed Central

The pvdA gene, encoding the enzyme L-ornithine N5-oxygenase, catalyzes a key step of the pyoverdin biosynthetic pathway in Pseudomonas aeruginosa. Expression studies with a promoter probe vector made it possible to identify three tightly iron-regulated promoter regions in the 5.9-kb DNA fragment upstream of pvdA. The promoter governing pvdA expression was located within the 154-bp sequence upstream of the pvdA translation start site. RNA analysis showed that expression of PvdA is iron regulated at the transcriptional level. Primer extension and S1 mapping experiments revealed two 5'termini of the pvdA transcript, 68 bp (T1) and 43 bp (T2) 5' of the PvdA initiation. The pvdA transcripts were monocystronic, with T1 accounting for 90% of the pvdA mRNA. Fur box-like sequences were apparently absent in the regions 5' of pvdA transcription start sites. A sequence motif resembling the -10 hexamer of AlgU-dependent promoters and the iron starvation box of pyoverdin genes controlled by the sigmaE -like factor PvdS were identified 5' of the T1 start site. The minimum DNA region required for iron-regulated promoter activity was mapped from bp -41 to -154 relative to the ATG translation start site of pvdA. We used pvdA'::lacZ transcriptional fusions and Northern (RNA) analyses to study the involvement of Fur and PvdS in the iron-regulated expression of pvdA. Two fur mutants of P. aeruginosa were much less responsive than wild-type PAO1 to the iron-dependent regulation of pvdA expression. Transcription from the pvdA promoter did not occur in a heterologous host unless in the presence of the pvdS gene in trans and was abrogated in a pvdS mutant of P. aeruginosa. Interaction of the Fur repressor with a 150-bp fragment encompassing the pvdS promoter was demonstrated in vivo by the Fur titration assay and confirmed in vitro by gel retardation experiments with a partially purified Fur preparation. Conversely, the promoter region of pvdA did not interact with Fur. Our results support the hypothesis that the P. aeruginosa Fur repressor indirectly controls pvdA transcription through the intermediary sigma factor PvdS; in the presence of sufficient iron, Fur blocks the pvdS promoter, thus preventing PvdS expression and consequently transcription of pvdA and other pyoverdin biosynthesis genes. PMID:8636031

Leoni, L; Ciervo, A; Orsi, N; Visca, P

1996-01-01

36

PVD and ECD-competition, alternative or combination?  

Microsoft Academic Search

Physical vapour deposition (PVD) and electrochemical deposition (ECD) both lead to film formation by the deposition of the material in atomic scale. On the base of advanced vacuum and plasma technologies, PVD processes have found their role in coating and thin film deposition, even if not comparable with “traditional” processes regarding the application volume. A lack of knowledge, coupled with

Hermann A. Jehn

1999-01-01

37

Influence of Commercial Pvd Deposition Parameters when Producing Tin Coatings  

Microsoft Academic Search

Physical Vapor Deposition (PVD) is a coating technique that relies on the creation of a vapor phase, under vacuum conditions, that condenses on a substrate to form a coating. PVD coatings of titanium nitride are commonly used in functional applications to promote faster cutting speeds and to prolong tool life, leading to operational cost savings and improved productivity. Some of

Shardonnay Bliss; Bryony James

2006-01-01

38

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

39

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

Microsoft Academic Search

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.

Satyesh K. Yadav; Jian Wang; Amit Misra; Xiang-Yang Liu; Ramamurthy Ramprasad

2012-01-01

40

Vapor Phase Deposition Using Plasma Spray-PVD  

NASA Astrophysics Data System (ADS)

Plasma spray—physical vapor deposition (PS-PVD) is a low pressure plasma spray technology to deposit coatings out of the vapor phase. PS-PVD is a part of the family of new hybrid processes recently developed by Sulzer Metco AG (Switzerland) on the basis of the well-established low pressure plasma spraying (LPPS) technology. Included in this new process family are plasma spray—chemical vapor deposition (PS-CVD) and plasma spray—thin film (PS-TF) processes. In comparison to conventional vacuum plasma spraying and LPPS, these new processes use a high energy plasma gun operated at a work pressure below 2 mbar. This leads to unconventional plasma jet characteristics which can be used to obtain specific and unique coatings. An important new feature of PS-PVD is the possibility to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats, but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional PVD technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and EB-PVD coatings. This paper reports on the progress made at Sulzer Metco to develop functional coatings build up from vapor phase of oxide ceramics and metals.

von Niessen, K.; Gindrat, M.; Refke, A.

2010-01-01

41

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, Erno

2008-01-01

42

Optimisation of PVdF-based polymer electrolytes  

NASA Astrophysics Data System (ADS)

An attempt was made to synthesise PVdF-based polymer electrolytes containing 1:1 EC:PC plasticiser in various salts such as LiAsF 6, LiPF 6 and LiBF 4 at different ratios using PVdF as homopolymer. Though, having a high ionic conductivity, certain films were found to be fragile, an indication of poor mechanical strength. Therefore, PVdF-PVC blend polymers were prepared using different ratios of PVdF-PVC as well as with different amounts of plasticiser mixture. Film characterisation was attempted using XRD, DSC, impedance and conductivity measurements. A particular combination of PVdF-PVC in the ratio 25:5 was observed to have high ionic conductivity and good mechanical strength. The electrochemical stability and the stability of lithium-polymer interface of the prepared polymer electrolytes were checked in terms of charge-discharge and impedance studies. Effect of storage time and cyclability are discussed.

Muniyandi, N.; Kalaiselvi, N.; Periyasamy, P.; Thirunakaran, R.; Ramesh babu, B.; Gopukumar, S.; Premkumar, T.; Renganathan, N. G.; Raghavan, M.

43

Investigation of microstructure and mechanical properties of multi-layer Cr/Cr2O3 coatings  

E-print Network

showed that coating thickness plays an important role in enhancing both physical vapor deposition (PVD-layer Microstructure Fracture toughness Adhesion Single and multi-layer Cr/Cr2O3 coatings were deposited by reactive of chromium oxide coatings fracture toughness in the literature. Various techniques have been used to deposit

Volinsky, Alex A.

44

Preparation of PVdF nanofiber membranes by electrospinning and their use as secondary battery separators  

Microsoft Academic Search

This paper reports the development and characterization of polyvinylidene fluoride (PVdF) nanofiber separators for high rate discharge secondary batteries. The preparation of PVdF nanofiber separators was performed by an electrospinning method. The pore properties of PVdF nanofiber separators were optimized by variation of spinning conditions, after post treatment and sheet forming. The optimized PVdF nanofiber separators were characterized by scanning

Kyungho Hwang; Byeongmin Kwon; Hongsik Byun

2011-01-01

45

Nanoscale Proteomics  

SciTech Connect

This paper describes efforts to develop a liquid chromatography (LC)/mass spectrometry (MS) technology for ultra-sensitive proteomics studies, i.e. nanoscale proteomics. The approach combines high-efficiency nano-scale LC with advanced MS, including high sensitivity and high resolution Fourier transform ion cyclotron resonance (FTICR) MS, to perform both single-stage MS and tandem MS (MS/MS) proteomic analyses. The technology developed enables large-scale protein identification from nanogram size proteomic samples and characterization of more abundant proteins from sub-picogram size complex samples. Protein identification in such studies using MS is feasible from <75 zeptomole of a protein, and the average proteome measurement throughput is >200 proteins/h and ~3 h/sample. Higher throughput (>1000 proteins/h) and more sensitive detection limits can be obtained using a “accurate mass and time” tag approach developed at our laboratory. These capabilities lay the foundation for studies from single or limited numbers of cells.

Shen, Yufeng; Tolic, Nikola; Masselon, Christophe D.; Pasa-Tolic, Liljiana; Camp, David G.; Anderson, Gordon A.; Smith, Richard D.; Lipton, Mary S.

2004-02-01

46

Nanoscale proteomics.  

PubMed

Efforts to develop a liquid chromatography (LC)/mass spectrometry (MS) technology for ultra-sensitive proteomics studies (i.e., nanoscale proteomics) are described. The approach combines high-efficiency nanoscale LC (separation peak capacity of approximately 10(3); 15-microm-i.d. packed capillaries with flow rates of 20 nL min(-1), the optimal separation linear velocity) with advanced MS, including high-sensitivity and high-resolution Fourier transform ion cyclotron resonance MS, to perform both single-stage MS and tandem MS (MS/MS) proteomic analyses. The technology enables broad protein identification from nanogram-size proteomics samples and allows the characterization of more abundant proteins from sub-picogram-size samples. Protein identification in such studies using MS is demonstrated from <75 zeptomole of a protein. The average proteome measurement throughput is approximately 50 proteins h(-1) using MS/MS during separations, presently requiring approximately 3 h sample(-1). Greater throughput (approximately 300 proteins h(-1)) and improved detection limits providing more comprehensive proteome coverage can be obtained by using the "accurate mass and time" tag approach developed in our laboratory. This approach provides a dynamic range of at least 10(6) for protein relative abundances and an improved basis for quantitation. These capabilities lay the foundation for studies from single or limited numbers of cells. PMID:14647945

Shen, Y; Toli?, N; Masselon, C; Pasa-Toli?, L; Camp, D G; Lipton, M S; Anderson, G A; Smith, R D

2004-02-01

47

Nanoscale 2013  

NASA Astrophysics Data System (ADS)

The accurate determination of the properties of micro- and nano-structures is essential in research and development. It is also a prerequisite in process control and quality assurance in industry. In most cases, especially at the nanometer range, knowledge of the dimensional properties of structures is the fundamental base, to which further physical properties are linked. Quantitative measurements presuppose reliable and stable instruments, suitable measurement procedures as well as calibration artifacts and methods. This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2013 seminar held in Paris, France, on 25 and 26 April. It was the 6th Seminar on NanoScale Calibration Standards and Methods and the 10th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Nanometrology Group of the Technical Committee-Length of EURAMET, the Physikalisch-Technische Bundesanstalt and the Laboratoire National de Métrologie et d'Essais. Three satellite meetings related to nanometrology were coupled to the seminar. The first one was an open Symposium on Scanning Probe Microscopy Standardization organized by the ISO/TC 201/SC9 technical committee. The two others were specific meetings focused on two European Metrology Research Projects funded by the European Association of National Metrology Institutes (EURAMET) (see www.euramet.org), the first one focused on the improvement of the traceability for high accuracy devices dealing with sub-nm length measurement and implementing optical interferometers or capacitive sensors (JRP SIB08 subnano), the second one aiming to develop a new metrological traceability for the measurement of the mechanical properties of nano-objects (JRP NEW05 MechProNo). More than 100 experts from industry, calibration laboratories and metrology institutes from around the world joined the NanoScale 2013 Seminar to attend 23 oral and 64 poster presentations. From these contributions, 22 are included as articles in this special issue of Measurement Science and Technology . They cover some novel scientific results that are representative of the topics currently being investigated in the field of European and world-wide nanometrology. Half of the articles presented in this special issue are linked to a quantitative use of atomic force microscopes (AFM) and related techniques. This is not surprising since atomic force microscopy with scanning electron microscopy (SEM) and scatterometry are the most used techniques to practice metrology at the nanometer scale. The presented developments around AFM mainly concern solutions to improve its performance, such as for example by increasing the scanning speed using dynamic control, its measurement range by using long-range AFM and even by automatically replacing the tip with 10 nm repositioning. The search for a better traceability is still on-going and a comparison of SEM and AFM organized in the Northern Europe research institutes illustrates this question well. But nowadays measurement on advanced product structures requires 3D capabilities. This can be achieved by using a new type of tilting AFM or more dedicated critical dimension (CD) AFMs that will use specific tips whose cantilever is sensitive in three dimensions. A perfect illustration of this are the results presented for the measurement of CD and sidewall on EUV photomasks. Calibration of the cantilever spring constant is still carried on and two papers present the latest developments. Finally, as past Nanoscale issues have witnessed, scanning probe microscopes are more and more used for metrological applications where the quantities to be measured are no longer dimensional, for example, thermal conductivity on delaminated thin films using a scanning thermal microscope, the carrier concentration on CIGS solar cells using a scanning capacitance microscope (SCM) or the surface potential measured by a Kelvin probe microscope. But in all cases, what these special developments share is a metrological approach, and for

Koenders, Ludger; Ducourtieux, Sebastien

2014-04-01

48

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

49

Microstructures and mechanical properties of sputtered Cu\\/Cr multilayers  

Microsoft Academic Search

The microstructures and mechanical properties of Cu\\/Cr multilayers prepared by sputtering onto {l_brace}100{r_brace} Si substrates at room temperature are presented. The films exhibit columnar grain microstructures with nanoscale grain sizes. The interfaces are planar and abrupt with no intermixing, as expected from the phase diagram. The multilayers tend to adopt a Kurdjumov-Sachs (KS) orientation relationship: {l_brace}110{r_brace}Cr \\/\\/ {l_brace}111{r_brace}Cu, <111>Cr \\/\\/

A. Misra; H. Kung; T. E. Mitchell; T. R. Jervis; M. Nastasi

1998-01-01

50

Wafer temperature measurement in PVD systems using the Co–Si reaction  

Microsoft Academic Search

It is becoming increasingly important to control the wafer temperature during IC processing, e.g. PVD. To measure the wafer temperature in PVD systems it is possible to use the Co–Si reaction. The difference in sheet resistance of the Co–Si phases, which form at different temperatures, is used to measure maximum wafer temperature in a PVD chamber. The maximum wafer temperature

A. M. van Graven; R. A. M. Wolters

2000-01-01

51

Analysis of field performance of embankments on soft clay deposit with and without PVD-improvement  

Microsoft Academic Search

This paper presents a case history of the performance of two full-scale test embankments constructed on soft clay deposit in the eastern coastal region of China. One embankment was constructed on natural subsoil and the other was constructed on prefabricated vertical drain (PVD) improved subsoil. The thickness of the soft clay deposit without PVD-improvement was 19m and with PVD-improved case

Shui-Long Shen; Jin-Chun Chai; Zhen-Shun Hong; Feng-Xi Cai

2005-01-01

52

Evolution of self-organization in nano-structured PVD coatings under extreme tribological conditions  

NASA Astrophysics Data System (ADS)

The evolution of the self-organization process where dissipative structures are formed under the extreme frictional conditions associated with high performance dry machining of hardened steels has been studied in detail. The emphasis was on the progressive studies of surface transformations within multilayer and monolayer TiAlCrSiYN-based PVD coatings during the running-in stage of wear when self-organization process occurs. The coating layer was characterized by high resolution electron energy-loss spectroscopy (HREELS). It is shown that the nano-multilayer coating possesses higher non-equilibrium structure in comparison to the monolayer. Comprehensive studies of the tribo-films (dissipative structures) formed on the friction surface were made using a number of advanced surface characterization techniques such as X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The data obtained for the tribo-films was combined with the detailed TEM studies of the structural and phase transformations within the underlying coating layer. This data was related to the micro-mechanical characteristics of the coating layer and its wear resistance. It was demonstrated that the evolution of the self-organization process is strongly controlled by the characteristics of the tribo-films formed at different stages of the wear process. Within running-in stage (after length of cut of 15 m) fully protective mullite tribo-films predominantly form on the surface of nano-multilayer coating, establishing a functional hierarchy within the layer of tribo-films. This reduces entropy production during friction and leads to significant surface damage reduction and wear rate stabilization. In contrast, in a monolayer coating with a lower structural complexity, a variety of protective and non-protective tribo-films form during the running-in stage, which cannot fully protect the surface. Therefore the wear rate on the monolayer is not stabilized and its wear resistance is lower. The results obtained show that it is possible to control tribo-films evolution during self-organization by means of increase in structural complexity and the non-equilibrium state of the surface engineered layer with simultaneous tuning of its integrative behaviour.

Fox-Rabinovich, G.; Kovalev, A.; Aguirre, M. H.; Yamamoto, K.; Veldhuis, S.; Gershman, I.; Rashkovskiy, A.; Endrino, J. L.; Beake, B.; Dosbaeva, G.; Wainstein, D.; Yuan, Junifeng; Bunting, J. W.

2014-04-01

53

Dissolution and soldering behavior of nitrided hot working steel with multilayer LAFAD PVD coatings  

Microsoft Academic Search

Soldering and corrosive dissolution are the primary causes of die non-performance in permanent mold and die casting production of net shape parts for the transportation industry. At worst, these corrosive reactions result in core pin or sprue dissolution, and at the least, some soldered cast metal remains behind when the casting is ejected. The objective of this work was to

V Joshi; K Kulkarni; R Shivpuri; R. S Bhattacharya; S. J Dikshit; D Bhat

2001-01-01

54

Ferroelectricity at the nanoscale  

NASA Astrophysics Data System (ADS)

The properties of ferroelectrics at the nanoscale are reviewed. The term nanoscale is here related to the ferroelectric film thickness (which is by an order of magnitude the size of the critical domain nucleus). The three aspects considered are ferroelectric switching, the scaling of the coercive field, and the bulk photovoltaic effect. While ferroelectricity at the nanoscale has a twenty-year history of study, it is only in the last few years that perovskite ferroelectric films have become a focus of interest.

Fridkin, V. M.; Ducharme, S.

2014-06-01

55

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

56

A study of PVD coatings and die materials for extended die-casting die life  

Microsoft Academic Search

There have been some applications of PVD coatings to extend die-casting die life, mainly by reducing molten metal corrosion and erosion to the die. However, die steel heat checking (or thermal cycling induced cracking) resistance is affected significantly by the PVD coatings. This paper presents the results of a systematic study involving three H series and two maraging hot work

Yucong Wang

1997-01-01

57

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 barrier coatings (TBCs) grown by electron-beam physical vapor deposition (EB-PVD) are key factors in determining the coating compliance, and consequently its resistance to spallation, as well as its thermal

Clarke, David R.

58

Feasibility of TiBN PVD Coating for Mill Rolls Laboratory Testing of Anti-adhesive and Fatigue Resistance Properties  

E-print Network

1 Feasibility of TiBN PVD Coating for Mill Rolls ­ Laboratory Testing of Anti-adhesive and Fatigue Vapour Deposition (PVD) are known for their high hardness. They offer a wide variety of friction for rolling mill rolls. TiBN is one of the PVD coatings with the highest hardness. It is also known for its

Paris-Sud XI, Université de

59

Hierarchical adaptive nanostructured PVD coatings for extreme tribological applications: the quest for nonequilibrium states and emergent behavior  

NASA Astrophysics Data System (ADS)

Adaptive wear-resistant coatings produced by physical vapor deposition (PVD) are a relatively new generation of coatings which are attracting attention in the development of nanostructured materials for extreme tribological applications. An excellent example of such extreme operating conditions is high performance machining of hard-to-cut materials. The adaptive characteristics of such coatings develop fully during interaction with the severe environment. Modern adaptive coatings could be regarded as hierarchical surface-engineered nanostructural materials. They exhibit dynamic hierarchy on two major structural scales: (a) nanoscale surface layers of protective tribofilms generated during friction and (b) an underlying nano/microscaled layer. The tribofilms are responsible for some critical nanoscale effects that strongly impact the wear resistance of adaptive coatings. A new direction in nanomaterial research is discussed: compositional and microstructural optimization of the dynamically regenerating nanoscaled tribofilms on the surface of the adaptive coatings during friction. In this review we demonstrate the correlation between the microstructure, physical, chemical and micromechanical properties of hard coatings in their dynamic interaction (adaptation) with environment and the involvement of complex natural processes associated with self-organization during friction. Major physical, chemical and mechanical characteristics of the adaptive coating, which play a significant role in its operating properties, such as enhanced mass transfer, and the ability of the layer to provide dissipation and accumulation of frictional energy during operation are presented as well. Strategies for adaptive nanostructural coating design that enhance beneficial natural processes are outlined. The coatings exhibit emergent behavior during operation when their improved features work as a whole. In this way, as higher-ordered systems, they achieve multifunctionality and high wear resistance under extreme tribological conditions.

Fox-Rabinovich, German S.; Yamamoto, Kenji; Beake, Ben D.; Gershman, Iosif S.; Kovalev, Anatoly I.; Veldhuis, Stephen C.; Aguirre, Myriam H.; Dosbaeva, Goulnara; Endrino, Jose L.

2012-08-01

60

Multilayer networks: Dangerous liaisons?  

NASA Astrophysics Data System (ADS)

Many networks interact with one another by forming multilayer networks, but these structures can lead to large cascading failures. The secret that guarantees the robustness of multilayer networks seems to be in their correlations.

Bianconi, Ginestra

2014-10-01

61

Magnetic pinning in superconductor-ferromagnet multilayers  

SciTech Connect

We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10{sup 6}-10{sup 7} A/cm{sup 2} at high temperatures (but not very close to T{sub c}) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics.

Bulaevskii, L. N. [Department of Physics and Astronomy, CUNY Lehman College 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States) [Department of Physics and Astronomy, CUNY Lehman College 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chudnovsky, E. M. [Department of Physics and Astronomy, CUNY Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States)] [Department of Physics and Astronomy, CUNY Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Maley, M. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2000-05-01

62

Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase  

Microsoft Academic Search

Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco\\u000a AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of\\u000a PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years.\\u000a In comparison

Konstantin von Niessen; Malko Gindrat

2011-01-01

63

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

64

The effects of length scale on the deformation behavior of metallic multilayers-Part II : modeling  

Microsoft Academic Search

The experimental observations described in a companion presentation of the same title by Misra et al. highlight that unique, non-bulk rolling textures are achieved in nanoscale multilayered thin films. Specifically, Cu\\/Nb multilayers deposited with an initial Kudjumov-Sachs orientation relation between Cu and Nb grains and with an initial individual layer thickness of 75nm preserve that relation during rolling. In contrast,

A. Misra; John Price Hirth; P. M. Anderson

2002-01-01

65

Nanoscale Stress Measurements and Standards  

E-print Network

Nanoscale Stress Measurements and Standards SEMICONDUCTORS Our objective is to develop accurate measurement methods for the nanoscale stress distributions and surface defects that control device performance % CAGR and 41 % US share. · Measurement of stress distributions around transistors in semiconductor

Magee, Joseph W.

66

Nanoscale Science and Engineering (NSE)  

NSF Publications Database

for Nanoscale Science and Engineering Centers (NSEC): Full proposals may ONLY be submitted by invitation from NSF. The National Science Foundation (NSF) announces a program on collaborative research and education in the area of nanoscale science and engineering. The goal of this program is to support fundamental research and catalyze synergistic science and engineering research and education in emerging areas of nanoscale science and technology, including: biosystems at the nanoscale; ...

67

Exploring at the Nanoscale  

NSDL National Science Digital Library

This lesson focuses on how nanotechnology has impacted our society and how engineers have learned to explore the world at the nanoscale. Learners participate in hands-on activities to understand exactly how small the nanoscale is, explore how surface area changes at the nano scale, and work in teams to develop futuristic applications of nanotechnology. Specifically, teams of learners examine and measure blocks of tofu or gelatin to determine the surface area. Then they slice the blocks into smaller and smaller pieces, exposing more surfaces, and impacting the surface area. Learners also explore the size of small by comparing various items to understand the size of nano.

Ieee

2013-02-25

68

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

69

Nanoscale thermal transport  

Microsoft Academic Search

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces

David G. Cahill; Wayne K. Ford; Kenneth E. Goodson; Gerald D. Mahan; Arun Majumdar; Humphrey J. Maris; Roberto Merlin; Simon R. Phillpot

2003-01-01

70

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

71

Microstructures and mechanical properties of sputtered Cu/Cr multilayers  

SciTech Connect

The microstructures and mechanical properties of Cu/Cr multilayers prepared by sputtering onto {l_brace}100{r_brace} Si substrates at room temperature are presented. The films exhibit columnar grain microstructures with nanoscale grain sizes. The interfaces are planar and abrupt with no intermixing, as expected from the phase diagram. The multilayers tend to adopt a Kurdjumov-Sachs (KS) orientation relationship: {l_brace}110{r_brace}Cr // {l_brace}111{r_brace}Cu, <111>Cr // <110>Cu. The hardness of the multilayered structures, as measured by nanoindentation, increase with decreasing layer thickness for layer thicknesses ranging from 200 nm to 50 nm, whereas for lower thicknesses the hardness of the multilayers is independent of the layer thickness. Dislocation-based models are used to interpret the variation of hardness with layer periodicity. The possible effects of factors such as grain size within the layers, density and composition of films and residual stress in the multilayers are highlighted. Comparisons are made to the mechanical properties of sputtered polycrystalline Cu/Nb multilayers which, like Cu/Cr, exhibit sharp fcc/bcc interfaces with no intermixing and a KS orientation relationship, but have a small shear modulus mismatch.

Misra, A.; Kung, H.; Mitchell, T.E.; Jervis, T.R.; Nastasi, M.

1998-03-01

72

Nanoscale ear drum: Graphene based nanoscale sensors  

E-print Network

The difficulty in determining the mass of a sample increases as its size diminishes. At the nanoscale, there are no direct methods for resolving the mass of single molecules or nanoparticles and so more sophisticated approaches based on electromechanical phenomena are required. More importantly, one demands that such nanoelectromechanical techniques could provide not only information about the mass of the target molecules but also about their geometrical properties. In this sense, we report a theoretical study that illustrates in detail how graphene membranes can operate as nanoelectromechanical mass-sensor devices. Wide graphene sheets were exposed to different types and amounts of molecules and molecular dynamic simulations were employed to treat these doping processes statistically. We demonstrate that the mass variation effect and information about the graphene-molecule interactions can be inferred through dynamical response functions. Our results confirm the potential use of graphene as mass detector dev...

Avdoshenko, Stas M; Cuniberti, Gianaurelio

2012-01-01

73

Structural characterization and high throughput screening of inhibitors of PvdQ, an NTN hydrolase involved in pyoverdine synthesis  

PubMed Central

The human pathogen Pseudomonas aeruginosa produces a variety of virulence factors including pyoverdine, a non-ribosomally produced peptide siderophore. The maturation pathway of the pyoverdine peptide is complex and provides a unique target for inhibition. Within the pyoverdine biosynthetic cluster is a periplasmic hydrolase, PvdQ, that is required for pyoverdine production. However, the precise role of PvdQ in the maturation pathway has not been biochemically characterized. We demonstrate herein that the initial module of the nonribosomal peptide synthetase PvdL adds a myristate moiety to the pyoverdine precursor. We extracted this acylated precursor, called PVDIq, from a pvdQ mutant strain and show that the PvdQ enzyme removes the fatty acid catalyzing one of the final steps in pyoverdine maturation. Incubation of PVDIq with crystals of PvdQ allowed us to capture the acylated enzyme and confirm through structural studies the chemical composition of the incorporated acyl chain. Finally, because inhibition of siderophore synthesis has been identified as a potential antibiotic strategy, we developed a high throughput screening assay and tested a small chemical library for compounds that inhibit PvdQ activity. Two compounds that block PvdQ have been identified and their binding within the fatty acid binding pocket structurally characterized. PMID:21892836

Drake, Eric J.; Gulick, Andrew M.

2011-01-01

74

Bilayer thickness effects on nanoindentation behavior of Ag/Ni multilayers  

E-print Network

by nanoindentation hardness and creep tests. The hardness increased with decreasing bilayer thickness, although as the bilayer thickness decreased below 8 nm there was a decrease in hardness that correlated well; Hardness; Hall­Petch relationship Multilayers with periodicity in the nanoscale range have attracted much

Hong, Soon Hyung

75

Modular, Multilayer Perceptron  

NASA Technical Reports Server (NTRS)

Combination of proposed modular, multilayer perceptron and algorithm for its operation recognizes new objects after relatively brief retraining sessions. (Perceptron is multilayer, feedforward artificial neural network fully connected and trained via back-propagation learning algorithm.) Knowledge pertaining to each object to be recognized resides in subnetwork of full network, therefore not necessary to retrain full network to recognize each new object.

Cheng, Li-Jen; Liu, Tsuen-Hsi

1991-01-01

76

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

77

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

78

DNA in Nanoscale Electronics  

NASA Astrophysics Data System (ADS)

DNA, the quintessential molecule of life, possesses a number of attractive properties for use in nanoscale circuits. Charge transport (CT) through DNA itself is of both fundamental and practical interest. Fundamentally, DNA has a unique configuration of ?-stacked bases in a well ordered, double helical structure. Given its unparalleled importance to life processes and its arrangement of conjugated subunits, DNA has been a compelling target of conductivity studies. In addition, further understanding of DNA CT will elucidate the biological implications of this process and advance its use in sensing technologies. We have investigated the fundamentals of DNA CT by measuring the electrochemistry of DNA monolayers under biologically-relevant conditions. We have uncovered both fundamental kinetic parameters to distinguish between competing models of operation as well as the practical implications of DNA CT for sensing. Furthermore, we are leveraging our studies of DNA conductivity for the manufacture of nanoscale circuits. We are investigating the electrical properties and self-assembly of DNA nanowires containing artificial base pair surrogates, which can be prepared through low cost and high throughput automated DNA synthesis. This unique and economically viable approach will establish a new paradigm for the scalable manufacture of nanoscale semiconductor devices.

Slinker, Jason

2012-10-01

79

Nanoscale thermal transport  

NASA Astrophysics Data System (ADS)

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid-solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime—experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The promise of improved thermoelectric materials and problems of thermal management of optoelectronic devices have stimulated extensive studies of semiconductor superlattices; agreement between experiment and theory is generally poor. Advances in measurement methods, e.g., the 3? method, time-domain thermoreflectance, sources of coherent phonons, microfabricated test structures, and the scanning thermal microscope, are enabling new capabilities for nanoscale thermal metrology.

Cahill, David G.; Ford, Wayne K.; Goodson, Kenneth E.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Merlin, Roberto; Phillpot, Simon R.

2003-01-01

80

Nanoscale thermal transport.  

SciTech Connect

Rapid progress in the synthesis and processing of materials with structure on nanometer length scales has created a demand for greater scientific understanding of thermal transport in nanoscale devices, individual nanostructures, and nanostructured materials. This review emphasizes developments in experiment, theory, and computation that have occurred in the past ten years and summarizes the present status of the field. Interfaces between materials become increasingly important on small length scales. The thermal conductance of many solid-solid interfaces have been studied experimentally but the range of observed interface properties is much smaller than predicted by simple theory. Classical molecular dynamics simulations are emerging as a powerful tool for calculations of thermal conductance and phonon scattering, and may provide for a lively interplay of experiment and theory in the near term. Fundamental issues remain concerning the correct definitions of temperature in nonequilibrium nanoscale systems. Modern Si microelectronics are now firmly in the nanoscale regime--experiments have demonstrated that the close proximity of interfaces and the extremely small volume of heat dissipation strongly modifies thermal transport, thereby aggravating problems of thermal management. Microelectronic devices are too large to yield to atomic-level simulation in the foreseeable future and, therefore, calculations of thermal transport must rely on solutions of the Boltzmann transport equation; microscopic phonon scattering rates needed for predictive models are, even for Si, poorly known. Low-dimensional nanostructures, such as carbon nanotubes, are predicted to have novel transport properties; the first quantitative experiments of the thermal conductivity of nanotubes have recently been achieved using microfabricated measurement systems. Nanoscale porosity decreases the permittivity of amorphous dielectrics but porosity also strongly decreases the thermal conductivity. The promise of improved thermoelectric materials and problems of thermal management of optoelectronic devices have stimulated extensive studies of semiconductor superlattices; agreement between experiment and theory is generally poor. Advances in measurement methods, e.g., the 3{omega} method, time-domain thermoreflectance, sources of coherent phonons, microfabricated test structures, and the scanning thermal microscope, are enabling new capabilities for nanoscale thermal metrology.

Cahill, D. G.; Ford, W. K.; Goodson, K. E.; Mahan, G. D.; Majumdar, A.; Maris, H. J.; Merlin, R.; Phillpot, S. R.; Materials Science Division; Univ. of Illinois; Intel Corp.; Stanford Univ.; Penn State Univ.; Univ. of California at Berkeley; Brown Univ.; Univ. of Michigan

2003-01-15

81

Nanoscale ear drum: Graphene based nanoscale sensors  

NASA Astrophysics Data System (ADS)

The difficulty in determining the mass of a sample increases as its size diminishes. At the nanoscale, there are no direct methods for resolving the mass of single molecules or nanoparticles and so more sophisticated approaches based on electromechanical phenomena are required. More importantly, one demands that such nanoelectromechanical techniques could provide not only information about the mass of the target molecules but also about their geometrical properties. In this sense, we report a theoretical study that illustrates in detail how graphene membranes can operate as nanoelectromechanical mass-sensor devices. Wide graphene sheets were exposed to different types and amounts of molecules and molecular dynamic simulations were employed to treat these doping processes statistically. We demonstrate that the mass variation effect and information about the graphene-molecule interactions can be inferred through dynamical response functions. Our results confirm the potential use of graphene as a mass detector device with remarkable precision in estimating variations in mass at the molecular scale and other physical properties of the dopants.

Avdoshenko, Stas M.; Gomes da Rocha, Claudia; Cuniberti, Gianaurelio

2012-05-01

82

Nanoscale ear drum: graphene based nanoscale sensors.  

PubMed

The difficulty in determining the mass of a sample increases as its size diminishes. At the nanoscale, there are no direct methods for resolving the mass of single molecules or nanoparticles and so more sophisticated approaches based on electromechanical phenomena are required. More importantly, one demands that such nanoelectromechanical techniques could provide not only information about the mass of the target molecules but also about their geometrical properties. In this sense, we report a theoretical study that illustrates in detail how graphene membranes can operate as nanoelectromechanical mass-sensor devices. Wide graphene sheets were exposed to different types and amounts of molecules and molecular dynamic simulations were employed to treat these doping processes statistically. We demonstrate that the mass variation effect and information about the graphene-molecule interactions can be inferred through dynamical response functions. Our results confirm the potential use of graphene as a mass detector device with remarkable precision in estimating variations in mass at the molecular scale and other physical properties of the dopants. PMID:22504575

Avdoshenko, Stas M; Gomes da Rocha, Claudia; Cuniberti, Gianaurelio

2012-05-21

83

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

84

Indirect heating of Pt by non-equilibrium electrons in Au in a nanoscale Pt/Au bilayer  

E-print Network

Indirect heating of Pt by non-equilibrium electrons in Au in a nanoscale Pt/Au bilayer Gyung multilayer on picosecond time-scales is controlled by the electronic thermal conductivity (e), the electronic interfacial thermal conductance (Gee), and electron-phonon coupling constant (g). We analyse heat transfer

Cahill, David G.

85

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

86

Interfacial effects in multilayers  

SciTech Connect

Interfacial structure and the atomic interactions between atoms at interfaces in multilayers or nano-laminates have significant impact on the physical properties of these materials. A technique for the experimental evaluation of interfacial structure and interfacial structure effects is presented and compared to experiment. In this paper the impact of interfacial structure on the performance of x-ray, soft x-ray and extreme ultra-violet multilayer optic structures is emphasized. The paper is concluded with summary of these results and an assessment of their implications relative to multilayer development and the study of buried interfaces in solids in general.

Barbee, T.W., Jr.

1998-04-01

87

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

88

High-performance chromium aluminium nitride PVD coatings on roller bearings  

Microsoft Academic Search

On the basis of cylindrical roller thrust bearings, it was systematically examined to what extent PVD coatings are able to take over the function of extreme pressure and anti-wear lubricant additives. The bearings were tested under heavy-duty conditions in order to quickly distinguish the efficiency of different coating substrate systems. Close regard is paid to the structure of the coatings.

K. Bobzin; E. Lugscheider; M. Maes; P. W. Gold; J. Loos; M. Kuhn

2004-01-01

89

On the use of ceramic PVD coatings to replace metallic coatings in electrical contacts  

Microsoft Academic Search

In electrical contacts the combination of high normal pressures and soft contact materials results in large contact areas and low contact resistance, but also in massive plastic deformation and wear. This paper examines some of the potential advantages and disadvantages of replacing one of the soft metallic coatings in electrical power connectors with a hard ceramic coating. Three ceramic PVD

Åsa Kassman Rudolphi; Staffan Jacobson

1997-01-01

90

Preparation of thermal barrier coatings for gas turbine blades by EB-PVD  

Microsoft Academic Search

Thermal barrier coatings for gas turbine blades have been coated by the EB-PVD method. This paper will mainly focus on two aspects of thermal barrier coatings: (i) the formation mechanism of the initial cracks during thermal cycle process; and (ii) the thermal barrier effect. The microcracks were only discovered inside the ceramic top coat of the thermalcycled TBCs. SEM\\/EDS observations

Huibin Xu; Shengkai Gong; Liang Deng

1998-01-01

91

Erosion, corrosion and erosion–corrosion of EB PVD thermal barrier coatings  

Microsoft Academic Search

Electron beam (EB) physical vapour deposited (PVD) thermal barrier coatings (TBCs) have been used in gas turbine engines for a number of years. The primary mode of failure is attributed to oxidation of the bond coat and growth of the thermally grown oxide (TGO), the alumina scale that forms on the bond coat and to which the ceramic top coat

R. G. Wellman; J. R. Nicholls

2008-01-01

92

Controlling Wear on Nanoscale  

NASA Astrophysics Data System (ADS)

One definition of wear in a tribological sense is that it is the progressive loss of mass from the operating surface of a body as a result of relative motion with another surface. Generally, tribology may be defined as the study of friction wear and lubrication, but in comparison with friction forces or lubrication methods, very little work has been done on the extremely important area of wear and surface damage. For systems consisting of common materials (metals, polymers, ceramics), there are at least four main mechanisms by which wear and surface damage can occur between solids in relative motion: abrasive-, adhesive-, chemical-, corrosive-, or fatigue-wear mechanisms. The occurrence of such different wear mechanisms involves the fundamental mechanics of molecular and supra-molecular scale. As a consequence, the understanding of surface properties on nanoscale level should be generated to also have a satisfactory knowledge of materials response on macrometer scale. Investigation of the fundamental characteristics of wear at the nanoscale is complicated by some factors and forces that acting on such scale level have not yet been addressed in the tribology of macro-systems. Since these forces are sensitive to the environment and surface condition of the specimens, it is quite difficult to determine them accurately. Further, quantification of wear is not straightforward since the amount of wear is often too small to be detected by surface-sensitive instruments. Nanowear measurements have been object of rapid development of precise measuring tools following to the introduction of scanning-probe microscopy (SPM) family. The advent of SPM family opened a new unique opportunity to study wear mechanisms on nanoscale, making possible to simulate one single asperity surface sliding on the other one and controlling many physical parameters during the contact dynamics. Further, SPM made possible to a have a direct connection between experimental data and theoretical models.

D'Acunto, Mario

93

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

94

A channelless, multilayer router  

SciTech Connect

We have implemented a channel-less, gridless, multilayer router as part of the Magic IC layout system. The router is designed to handle new routing problems associated with emerging technologies such as Wafer Scale Integration and multilayered metal processes. Three features distinguish this router: rectilinear Steiner trees with floating segments, a routing scheduler, and a corner-stitched database. 7 refs., 2 figs., 4 tabs.

Lunow, R.E.

1988-03-15

95

Nanoscale relaxation oscillator  

DOEpatents

A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.

Zettl, Alexander K. (Kensington, CA); Regan, Brian C. (Los Angeles, CA); Aloni, Shaul (Albany, CA)

2009-04-07

96

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam  

NASA Astrophysics Data System (ADS)

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 ?m and 90 nm, respectively. Their aspect ratio was about 17.

Naoyuki Fukutake,; Nozomi Miyoshi,; Yuya Takasawa,; Tatsuya Urakawa,; Tomoko Gowa,; Kazumasa Okamoto,; Akihiro Oshima,; Seiichi Tagawa,; Masakazu Washio,

2010-06-01

97

Micro- and Nano-Scale Fabrication of Fluorinated Polymers by Direct Etching Using Focused Ion Beam  

NASA Astrophysics Data System (ADS)

Micro- and nano-scale fabrications of various fluorinated polymers were demonstrated by direct maskless etching using a focused ion beam (FIB). The etching rates of perfluorinated polymers, such as poly(tetrafluoroethylene) (PTFE), poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP), poly(tetrafluoroethylene-co-perfluoroalkoxyvinylether) (PFA), were about 500-1000 times higher than those of partially fluorinated polymers, such as poly(tetrafluoroethylene-co-ethylene) (ETFE) and poly(vinilydene-fluoride) (PVdF). Controlled high quality and high aspect-ratio nanostructures of spin-coated cross-linked PTFE were obtained without solid debris. The height and diameter of the fibers were about 1.5 µm and 90 nm, respectively. Their aspect ratio was about 17.

Fukutake, Naoyuki; Miyoshi, Nozomi; Takasawa, Yuya; Urakawa, Tatsuya; Gowa, Tomoko; Okamoto, Kazumasa; Oshima, Akihiro; Tagawa, Seiichi; Washio, Masakazu

2010-06-01

98

Thermal Conductivity of EB-PVD Thermal Barrier Coatings Evaluated by a Steady-State Laser Heat Flux Technique  

NASA Technical Reports Server (NTRS)

The thermal conductivity of electron beam-physical vapor deposited (EB-PVD) Zr02-8wt%Y2O3 thermal barrier coatings was determined by a steady-state heat flux laser technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser high heat flux, long term test conditions. The thermal conductivity increase due to micro-pore sintering and the decrease due to coating micro-delaminations in the EB-PVD coatings were evaluated for grooved and non-grooved EB-PVD coating systems under isothermal and thermal cycling conditions. The coating failure modes under the high heat flux test conditions were also investigated. The test technique provides a viable means for obtaining coating thermal conductivity data for use in design, development, and life prediction for engine applications.

Zhu, Dongming; Miller, Robert A.; Nagaraj, Ben A.; Bruce, Robert W.

2000-01-01

99

Thermal conductivity of EB-PVD thermal barrier coatings evaluated by a steady-state laser heat flux technique  

Microsoft Academic Search

The thermal conductivity of electron beam-physical vapor deposited (EB-PVD) ZrO2–8 wt.%Y2O3 thermal barrier coatings was determined by a steady-state laser heat flux technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser high heat flux, long-term test conditions. The thermal conductivity increase due to micro-pore sintering and the

Dongming Zhu; Robert A. Miller; Ben A. Nagaraj; Robert W. Bruce

2001-01-01

100

Templated nanoscale porous carbons.  

PubMed

This manuscript reviews key developments in the important and rapidly expanding area of templated porous carbons. The porosity covered ranges from microporous to mesoporous and macroporous carbons. Two modes of templating, using so-called hard and soft templates, are covered. In particular, for hard templating, zeolite templating generates microporous carbons, mesoporous silicates yield mesoporous carbons, while colloidal particles are replicated to large mesoporous and macroporous carbons. Soft-templating, a more recent phenomenon, mainly generates mesoporous carbons. The full range of pore sizes can therefore now be accessed using hard and soft templates to generate highly ordered nanoscale carbons with well-defined and optimised textural properties. The research area has seen rapid and important developments over the last few years, and this review aims to present the more significant advances. PMID:20648305

Xia, Yongde; Yang, Zhuxian; Mokaya, Robert

2010-05-01

101

Nanoscale data storage  

E-print Network

The object of this article is to review the development of ultrahigh-density, nanoscale data storage, i.e., nanostorage. As a fundamentally new type of storage system, the recording mechanisms of nanostorage may be completely different to those of the traditional devices. Currently, two types of molecules are being studied for potential application in nanostorage. One is molecular electronic elements including molecular wires, rectifiers, switches, and transistors. The other approach employs nanostructured materials such as nanotubes, nanowires, and nanoparticles. The challenges for nanostorage are not only the materials, ultrahigh data-densities, fabrication-costs, device operating temperatures and large-scale integration, but also the development of the physical principles and models. There are already some breakthroughs obtained, but it is still unclear what kind of nanostorage systems can ultimately replace the current silicon based transistors. A promising candidate may be a molecular-nanostructure hybrid device with sub-5 nm dimensions.

J. C. Li

2007-01-29

102

Galvanic corrosion properties of differently PVD-treated magnesium die cast alloy AZ91  

Microsoft Academic Search

Different types of PVD coatings and plasma treatments were applied for the surface treatment of magnesium die cast alloy AZ91 specimens. The different types of surface treatment were all developed by the authors and the fundamental properties are described elsewhere. The coating systems were:•9 ?m CrN hard coating•3 ?m TiN coating•0.5 ?m plasma anodisation layer and 3 ?m Al2O3 coatingThe

H. Hoche; C. Blawert; E. Broszeit; C. Berger

2005-01-01

103

Oxidation-induced failure of EB-PVD thermal barrier coatings  

Microsoft Academic Search

Oxidation-induced failure of EB-PVD thermal barrier coatings (TBC) deposited on a single-crystal superalloy with a platinum aluminide bond coat has been studied in order to determine the specific mechanisms leading to TBC spallation. Cyclic oxidation tests performed at 1150°C show that failure of the TBC occurs when the alumina scale, growing at the bond coat–TBC interface, attains its critical thickness.

V. K Tolpygo; D. R Clarke; K. S Murphy

2001-01-01

104

Micro-abrasive wear of PVD duplex and single-layered coatings  

Microsoft Academic Search

A micro-abrasive wear test has been used to evaluate the wear resistance of duplex coatings, consisting of plasma nitriding followed by PVD coating. Two duplex coatings were investigated: TiAlN and TiN. Single-layered TiAlN and TiN coatings were also tested to evaluate the effect of the duplex treatment on wear resistance. Prior to wear testing, coating properties were evaluated by hardness,

J. C. A. Batista; A. Matthews; C. Godoy

2001-01-01

105

Performance of PVD MoS 2\\/Zr-coated carbide in cutting processes  

Microsoft Academic Search

MoS2\\/Zr composite coatings were deposited on the surface of YT15-cemented carbide. Microstructural and fundamental properties of these coatings were examined. Dry cutting and sliding wear tests on hardened steel were carried out with these coated tools. Results showed that PVD MoS2\\/Zr composite coatings onto the cemented carbide substrate show higher hardness and better adhesion with the substrate in comparison with

Deng Jianxin; Song Wenlong; Zhang Hui; Zhao Jinlong

2008-01-01

106

Microstructural studies of TiN coatings prepared by PVD and IBAD  

NASA Astrophysics Data System (ADS)

Titanium nitride (TiN) films have been deposited by physical vapour deposition (PVD), with BALZER equipment, and ion beam assisted deposition (IBAD) process, in DANFYSIK chamber. TiN thin films were grown, during IBAD process, by evaporation of Ti in presence of N 2 and simultaneous bombarded with Ar + ions. The evolution of the microstructure from porous and columnar grains to densel packed grains is accompanied by changes in mechanical and physical properties.

Škori?, Branko; Kakaš, Damir; Bibic, Natasa; Rakita, Milan

2004-09-01

107

Nanoscale deformation mechanism of TiC/a-C nanocomposite thin films  

SciTech Connect

This paper concentrates on the deformation behavior of amorphous diamondlike carbon composite materials. Combined nanoindentation and ex situ cross-sectional transmission electron microscopy investigations are carried out on TiC/a-C nanocomposite films, with and without multilayered structures deposited by pulse dc magnetron sputtering. It is shown that by controlling the distribution of nanocrystallites forming nanoscale multilayers, the system can be used as a 'microstructural ruler' that is able to distinguish various deformation patterns, which can be hardly detected otherwise in a homogeneous structure. It is shown that rearrangement of nanocrystallites and displacement of a-C matrix occur at length scales from tens of nanometer down to 1 nm. At submicrometer scale homogeneous nucleation of multiple shear bands has been observed within the nanocomposites. The multilayered structure in the TiC/a-C nanocomposite film contributes to an enhanced toughness.

Chen, C. Q.; Pei, Y. T.; Shaha, K. P.; De Hosson, J. Th. M. [Department of Applied Physics, Materials Innovation Institute M2i, University of Groningen, Nijenborgh 4, 9747 AG Groningen (Netherlands)

2009-06-01

108

Nanoscale laser processing and diagnostics  

Microsoft Academic Search

The article summarizes research activities of the Laser Thermal Laboratory on pulsed nanosecond and femtosecond laser-based\\u000a processing of materials and diagnostics at the nanoscale using optical-near-field processing. Both apertureless and apertured\\u000a near-field probes can deliver highly confined irradiation at sufficiently high intensities to impart morphological and structural\\u000a changes in materials at the nanometric level. Processing examples include nanoscale selective subtractive

David Hwang; Sang-Gil Ryu; Nipun Misra; Hojeong Jeon; Costas P. Grigoropoulos

2009-01-01

109

Particle Defect Reduction in the Endura Titanium Nitride PVD Sputter System  

SciTech Connect

Particles are inevitably generated in physical vapor deposition (PVD) systems due to the delamination of deposited films on various process chamber parts and shielding. Non-collimated (blanket) and collimated PVD Titanium Nitride (TiN) deposition processes are used for metal ARC (anti-reflective coating) and underlayers, and for the "contact liner" deposition steps (TiN adhesion layers before plug formation). Probe yield analysis and SRAM bit failure analysis, using conventional failure analysis, have shown that particles at these process steps can have a significant impact on wafer yields. In many typical semiconductor wafer fabs, particles generated by TiN film deposition rank consistently at or near the top of the defect pareto. This paper summarizes the results of defect reduction experiments conducted on an Applied Materials Endura Physical Vapor Deposition (PVD) system and various off-line experiments examining film and adhesion characteristics. It includes the results of film adhesion and shield temperature control experiments aimed at reducing defect levels. Key fidings, particle reduction results, and recommended defect reduction measures are presented. The reduction in particles not only can improve yields, but also result in substantial cost savings through the extension of chamber kit end-of-life (EOL).

Louis, Mark D.; Ohlhausen, Tony; Peebles, Diane; Specner, Roger; Whitehair, Hal

1999-06-24

110

Multilayer Ceramic Capacitor.  

National Technical Information Service (NTIS)

The multilayer capacitor has the plates arranged vertically, which allows planar attachment with conductive epoxy to a substrate such a thick film conductor on alumina. The top termination may use wire bonding. The capacitor has the same form factor and s...

R. D. Larowe

1984-01-01

111

Multilayer Thermionic Refrigeration  

Microsoft Academic Search

A new method of refrigeration is proposed. Efficient cooling is obtained by thermionic emission of electrons over Schottky barriers between metals and semiconductors. Since the barriers have to be thin, each barrier can have only a small temperature difference (â¼1 K) . Macroscopic cooling is obtained with a multilayer device. The same device is also an efficient generator of electrical

G. D. Mahan; L. M. Woods

1998-01-01

112

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

113

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

114

Electrostatics at the nanoscale.  

PubMed

Electrostatic forces are amongst the most versatile interactions to mediate the assembly of nanostructured materials. Depending on experimental conditions, these forces can be long- or short-ranged, can be either attractive or repulsive, and their directionality can be controlled by the shapes of the charged nano-objects. This Review is intended to serve as a primer for experimentalists curious about the fundamentals of nanoscale electrostatics and for theorists wishing to learn about recent experimental advances in the field. Accordingly, the first portion introduces the theoretical models of electrostatic double layers and derives electrostatic interaction potentials applicable to particles of different sizes and/or shapes and under different experimental conditions. This discussion is followed by the review of the key experimental systems in which electrostatic interactions are operative. Examples include electroactive and "switchable" nanoparticles, mixtures of charged nanoparticles, nanoparticle chains, sheets, coatings, crystals, and crystals-within-crystals. Applications of these and other structures in chemical sensing and amplification are also illustrated. PMID:21321754

Walker, David A; Kowalczyk, Bartlomiej; de la Cruz, Monica Olvera; Grzybowski, Bartosz A

2011-04-01

115

Hybrid diffusive/PVD treatments to improve the tribological resistance of Ti-6Al-4V.  

PubMed

Titanium alloys are nowadays used for a wide range of biomedical applications thanks to their combination of high mechanical resistance, high corrosion resistance and biocompatibility. Nevertheless, the applicability of titanium alloys is sometimes limited due to their low microhardness and tribological resistance. Thus the titanium alloys cannot be successfully applied to prosthetic joint couplings. A wide range of surface treatments, in particular PVD coatings such as CrN and TiN, have been used in order to improve the tribological behaviour of titanium alloys. However, the low microhardness of the titanium substrate often results in coating failure due to cracks and delamination. For this reason, hybrid technologies based on diffusive treatments and subsequent PVD coatings may improve the overall coating resistance. In this work, conventional PVD coatings of CrN or TiCN, deposited on Titanium Grade 5, were characterized and then combined with a standard thermal diffusive nitriding treatment in order to improve the tribological resistance of the titanium alloys and avoid coating delamination. The different treatments were studied by means of scanning electron microscopy both on the sample surface and in cross-section. In-depth composition profiles were obtained using glow discharge optical emission spectrometry (GDOES) and localized energy dispersive X-ray diffraction on linear scan-lines. The microhardness and adhesion properties of the different treatments were evaluated using Vickers microhardness tests at different load conditions. The indentations were observed by means of SEM in order to evaluate delaminated areas and the crack's shape and density. The tribological behaviour of the different treatments was tested in dry conditions and in solution, in alternate pin-on-flat configuration, with a frequency of 0.5 Hz. After testing, the surface was investigated by means of stylus profilometry and SEM both on the surface and in cross-section. The standalone PVD coatings show a limited tribological resistance due to the low hardness of the substrate, which results in fractures and delamination. The combination of a diffusive process and a subsequent PVD coating shows a stronger effect in improving the tribological resistance of the substrate. PMID:24211942

Marin, E; Offoiach, R; Lanzutti, A; Regis, M; Fusi, S; Fedrizzi, L

2014-01-01

116

Design and Synthesis of Bimetallic Electrocatalyst with Multilayered Pt-Skin Surfaces  

SciTech Connect

Advancement in heterogeneous catalysis relies on the capability of altering material structures at the nanoscale, and that is particularly important for the development of highly active electrocatalysts with uncompromised durability. Here, we report the design and synthesis of a Pt-bimetallic catalyst with multilayered Pt-skin surface, which shows superior electrocatalytic performance for the oxygen reduction reaction (ORR). This novel structure was first established on thin film extended surfaces with tailored composition profiles and then implemented in nanocatalysts by organic solution synthesis. Electrochemical studies for the ORR demonstrated that after prolonged exposure to reaction conditions, the Pt-bimetallic catalyst with multilayered Pt-skin surface exhibited an improvement factor of more than 1 order of magnitude in activity versus conventional Pt catalysts. The substantially enhanced catalytic activity and durability indicate great potential for improving the material properties by fine-tuning of the nanoscale architecture.

Wang, Chao [Argonne National Laboratory (ANL); Chi, Miaofang [ORNL; Li, Dongguo [Argonne National Laboratory (ANL); Strmcnik, Dusan [Argonne National Laboratory (ANL); Van der Vliet, Dennis [Argonne National Laboratory (ANL); Wang, Guofeng [Indiana University and Purdue University; Komanicky, Vladimir [Argonne National Laboratory (ANL); Chang, Kee-Chul [Argonne National Laboratory (ANL); Paulikas, Arvydas [Argonne National Laboratory (ANL); Tripkovic, Dusan [Argonne National Laboratory (ANL); Pearson, John [Argonne National Laboratory (ANL); More, Karren Leslie [ORNL; Markovic, Nenad [Argonne National Laboratory (ANL); Stamenkovic, Vojislav [Argonne National Laboratory (ANL)

2011-01-01

117

Multilayer reactive foils: Fabrication, reaction characterization, and room-temperature joining  

Microsoft Academic Search

The self-propagating reactive multilayer foils studied here were composed of alternating nanoscale layers of Al and Ni. The reactions associated with these foils can reach temperatures well over 1600°C with propagation velocities one the order of 1 to 10 m\\/s. In order to characterized these reactions, a high spatial resolution (50 micron), high temporal resolution (25 microsecond) and high temperature

Michael Eric Reiss

2003-01-01

118

Giant magnetoresistance in multilayers  

NASA Astrophysics Data System (ADS)

We studied ballistic conductance in the current perpendicular-to-the-plane geometry (CPP) in various types of multilayer systems. The goal was to see to what extent the band structure matching in these multilayer systems is responsible for the giant magneto-resistance effect (GMR) and how GMR depends on the various parameters of the samples. The band structure was taken into account through a realistic third-nearest-neighbor tight-binding model with s, p and d orbitals. The Landauer formula was used to calculate the conductance of the two spin channels. The method is based on efficiently calculating the Green's function of the leads and the slab using the transfer matrix approach. Using this framework we studied the dependence of GMR on the size of the spacer and magnetic slabs and the number of periods in conventional multilayers. The ballistic conductance and GMR were found to saturate quickly with the number of periods in the multilayer. Next, we investigated the angular dependence of the conductance and giant magnetoresistance in spin-valve structures. The conductance, due to both minority and majority spin channels, was calculated for arbitrary angles between the magnetizations of the magnetic layers. We found that the leading contribution to the conductance is proportional to the cosine of the angle between the magnetizations of the magnetic layers. Next, we present theoretical studies on the size-dependence of the CPP GMR in nanowires. We find that the conductance of the minority channel in the parallel configuration increases very slowly with the nanowire size. At the same time, the conductance of all other channels reaches the value observed in multilayers at very small nanowire size. This limits the GMR ratio to only a fraction of the multilayer value for small nanowires. Finally, we study the dependence of GMR on the size of the nanowire for medium size nanowires. We propose a scheme exploiting the symmetry of the wire to break the problem into several disconnected problems for the different symmetry type wave functions, which can live on the wire.

Velev, Julian Petkov

119

A Nanoscale Mechanism for Protein Control  

NSF Publications Database

... Mechanism for Protein Control The nanoscale spring-loaded control mechanism Credit and Larger ... have created a nanoscale mechanism to control the function of virtually any protein. These new ...

120

NANOSCALE BIOSENSORS IN ECOSYSTEM EXPOSURE RESEARCH  

EPA Science Inventory

This powerpoint presentation presented information on nanoscale biosensors in ecosystem exposure research. The outline of the presentation is as follows: nanomaterials environmental exposure research; US agencies involved in nanosensor research; nanoscale LEDs in biosensors; nano...

121

Nanoscale Superconductivity:. Physics and Applications  

NASA Astrophysics Data System (ADS)

Conventional superconductivity in bulk objects is characterized by three phenomenological features: zero resistivity, perfect diamagnetism (Meissner effect) and energy gap in the excitation spectrum. In this paper we demonstrate that these attributes of superconductivity do not apply to ultra-small objects governed by the essentially nanoscale phenomenon which is quantum fluctuations. The observation results in fundamental limitations of utilization of superconducting elements in nanoelectronic circuits. However, together with this rather pessimistic conclusion, the indicated size phenomena lead to a new class of nanoscale devices and applications.

Arutyunov, K.

2013-05-01

122

Center for Nanoscale Science and Technology  

National Institute of Standards and Technology Data Gateway

NIST Center for Nanoscale Science and Technology (Program website, free access)   Currently there is no database matching your keyword search, but the NIST Center for Nanoscale Science and Technology website may be of interest. The Center for Nanoscale Science and Technology enables science and industry by providing essential measurement methods, instrumentation, and standards to support all phases of nanotechnology development, from discovery to production.

123

Nanoscale Science and Engineering Education (NSEE)  

NSF Publications Database

[A] Nanoscale Informal Science Education (NISE): This effort is intended to foster public awareness, engagement, and understanding of nanoscale science, engineering, and technology through establishment of a Network, a national infrastructure that links science museums and other informal science education organizations with nanoscale science and engineering research organizations. Specifically, the NISE component will establish a national infrastructure that links science museums and other ...

124

Atomic Assembly of Magnetoresistive Multilayers  

E-print Network

are controlled using patterning methods and selective etching methods which have been facilitated by rapid junction (MTJ) [9­ 12] multilayers. GMR multilayers are composed of 20­50 °A thick magnetic metal layers. MTJ multilayers are composed of a pair of 20­50 °A thick NiCoFe alloy layers sandwiching a 10­20 °A

Wadley, Haydn

125

Nucleation and Growth of Bubbles in He Ion Implanted V/Ag Multilayers,  

SciTech Connect

Microstructures of He ion-implanted pure Ag, pure V and polycrystalline V/Ag multilayers with individual layer thickness ranging from 1?nm to 50?nm were investigated by transmission electron microscopy (TEM). The bubbles in the Ag layer were faceted and larger than the non-faceted bubbles in the V layer under the same implantation conditions for both pure metals and multilayers. The substantially higher single defects surviving the spike phase and lower mobility of trapped He in bcc than those in fcc could account for this difference. For multilayers, the bubbles nucleate at interfaces but grow preferentially in Ag layers due to high mobility of trapped He in fcc Ag. In addition, the He concentration above which bubbles can be detected in defocused TEM images increases with decreasing layer thickness, from 0 for pure Ag to 4–5 at. % for 1?nm V/1?nm Ag multilayers. In contrast, the bubble size decreases with decreasing layer thickness, from approximately 4?nm in diameter in pure Ag to 1?nm in the 1?nm V/1?nm Ag multilayers. Elongated bubbles confined in the Ag layer by the V–Ag interfaces were observed in 1?nm multilayers. These observations show that bubble nucleation and growth can be suppressed to high He concentrations in nanoscale composites with interfaces that have high He solubility.

Wei, Q. M.; Wang, Y. Q.; Nastasi, Michael; Misra, A.

2011-01-01

126

Advanced STEM Characterization of Nanoscale Materials  

NASA Astrophysics Data System (ADS)

Nanoscale materials are the key structures in determining the properties of many technologically-important materials. Two such important nanoscale materials for different technological applications are investigated in this dissertation. They are: Fischer-Tropsch (FT) catalysts and irradiated metallic bi-layers. Catalytic activity depends on the structural parameters such as size, shape, and distribution on support. On the other hand, the radiation resistance of the model metallic multi-layers is influenced by the presence of interphase, phase-boundaries, and grain-boundaries. The focus of this dissertation is to use different TEM and STEM techniques to understand the structure of these materials. This dissertation begins with a review of the microscopy techniques used in the experiments. Then, in the next two chapters, literature review followed by results and discussions on the two above-mentioned nano materials are presented. Future research directions are included in the concluding chapter. To obtain three-dimensional morphological information of the FT catalysts during reduced/active state, STEM tomography is used. The oxidized state and reduced state is clarified by using STEM-EELS (in the form of spectrum imaging). We used a special vacuum transfer tomography holder and ex-situ gas assembly for reduction, and the reduction parameters are optimized for complete reduction. It was observed that the particle was reduced with 99.99% H2, and at 400°C for 15 minutes. The tomographic results in before-reduction condition depict that the Co-oxide particles are distributed randomly inside the alumina support. After reduction, the tomogram reveals that metallic Co nucleated and sintered towards the surface of the alumina support. The overall metallic Co distribution shows an outward segregation by subsurface diffusion mechanism. In the study of metallic bi-layer, He-irradiated gold twist grain boundary (AuTGB) was chosen as it is one of the least-studied systems in the area of model metallic multi-layers materials. Traditional TEM techniques such as two-beam imaging, weak beam imaging, and through-focal series have been applied to characterize the dislocation network and He bubble distribution. STEM Z-contrast imaging has also been applied to characterize the dislocation network and He bubble distribution. The TGB is found to consist of grid (square, rectangular) of screw dislocations with a line direction along <110> and with Burgers vector1/2a<110>. The He bubble distribution is found to be random across the thickness. The results showed that, because of STEM's characteristic dependence on atomic number, STEM imaging reduces the post-processing of images and provides 3D information about distribution of the radiation damage which is unobtainable by TEM. In summary, this dissertation makes important contributions to the knowledge of FT catalyst by providing direct, reliable representation of 3D structure of a FT catalyst after reduction and irradiated metallic-bilayer knowledge base by presenting new results which will help in designing new materials and fabrication techniques.

Dey, Sanchita

127

Nanoscale Strength Measurements and Standards  

E-print Network

grips. The test specimen is diametrally compressed via instrumented indentation, or nanoindentationNanoscale Strength Measurements and Standards CERAMICS To develop new mechanical test structures device reliability. Test specimens include as-deposited thin films, in addition to theta and C

Perkins, Richard A.

128

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

129

Failure of PVD/plasma sprayed thermal barrier coatings during thermal cycling  

SciTech Connect

ZrO{sub 2}7Y{sub 2}O{sub 3} plasma sprayed coatings (PS top coating) were applied on high temperature Ni-based alloys precoated by Physical Vapor Deposition with a thin, dense, stabilized zirconia coating (PVD bond coat). The PS coatings were applied by Atmospheric Plasma Spraying (APS) and Inert gas Plasma Spraying (IPS at 2 bar) for different substrate temperatures. The thermal barrier coatings (TBCs) were tested by furnace isothermal cycling and flame thermal cycling at maximum temperatures between 1,000 C and 1,150 C. The temperature gradients within the duplex PVD/PS thermal barrier coatings during the thermal cycling process were modeled using an unsteady heat transfer program. This modeling enables the authors to calculate the transient thermal strains and stresses which contribute to a better understanding of the failure mechanisms of the TBC during thermal cycling. They have also studied experimentally the adherence and failure modes of these coating systems during this high temperature testing. The TBC failure mechanism during thermal cycling is discussed in the light of coating transient stresses and substrate oxidation.

Teixeria, V.; Andritschky, M. [Univ. of Minho, Braga (Portugal); Gruhn, H.; Mallener, W.; Buchkremer, H.; Stoever, D. [Forschungszentrum Juelich GmbH (Germany)

1995-12-31

130

Multilayer graphene waveguides  

NASA Astrophysics Data System (ADS)

We study dispersion properties of TM-polarized electromagnetic waves guided by a multilayer graphene metamaterial. We demonstrate that both dispersion and localization of the guided modes can be efficiently controlled by changing the number of layers in the structure. Remarkably, we find that in the long wavelength limit, the dispersion of the fundamental mode of the N-layer graphene structure coincides with the dispersion of a plasmon mode supported by a single graphene layer, but with N times larger conductivity. We also compare our exact dispersion relations with the results provided by the effective media model.

Smirnova, D. A.; Iorsh, I. V.; Shadrivov, I. V.; Kivshar, Y. S.

2014-06-01

131

Multilayer heat insulator  

SciTech Connect

The invention relates to multilayer heat insulators wherein gasimpermeable layers each made of a metal foil of one member selected from the group consisting of aluminum, nickel and stainless steel and gas-containing layers each made of at least one member selected from the group consisting of glass fiber, asbestos fiber, mineral fiber, ceramic fiber, carbon fiber, silica powder, alumina powder and zirconia powder in the form of wool, paper or mat are laminated alternately so that the same layers do not contact each other. The thickness of the gasimpermeable layer is 10 to 20 mu m, the thickness of the gascontaining layer is 0.3 to 1.8 mm and its porosity is 0.98 to 95 to make the thermal conductivity of this lamina multilayer heat insulator about 0.02 kcal/mh0 C (2000 C) so that the behavior of the contained gas may be as small as possible, the thermal conduction may be prevented and the heat insulating performance may be improved.

Iwabuchi, S.; Matsui, K.

1982-04-06

132

Investigation of low-reflective ZrCN–PVD-arc coatings for application on medical tools for minimally invasive surgery  

Microsoft Academic Search

Medical tools for minimally invasive surgery are often used under difficult environmental conditions. If the surgeons have to work with a microscope, the operating area must be brightly lit. Reflection and scattering of light from tool-surfaces disturb the visual field. To decrease this kind of disturbance, the tools can be covered by a dark PVD thin film. In the present

F Hollstein; D Kitta; P Louda; F Pacal; J Meinhardt

2001-01-01

133

The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings  

Microsoft Academic Search

Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with

R. B. Dinwiddie; S. C. Beecher; W. D. Porter; B. A. Nagaraj

1996-01-01

134

Characterization of the PvdS-regulated promoter motif in Pseudomonas syringae pv. tomato DC3000 reveals  

E-print Network

Characterization of the PvdS-regulated promoter motif in Pseudomonas syringae pv. tomato DC3000S, a group IV sigma factor encoded by Pseudomonas syringae pv. tomato DC3000 (DC3000), a plant pathogen, 2002; Potvin et al., 2008). The model plant pathogen Pseudomonas syringae pv. tomato DC3000 (DC3000

Myers, Chris

135

The effects of length scale on the deformation behavior of metallic multilayers-Part II : modeling /.  

SciTech Connect

The experimental observations described in a companion presentation of the same title by Misra et al. highlight that unique, non-bulk rolling textures are achieved in nanoscale multilayered thin films. Specifically, Cu/Nb multilayers deposited with an initial Kudjumov-Sachs orientation relation between Cu and Nb grains and with an initial individual layer thickness of 75nm preserve that relation during rolling. In contrast, samples with micron-scale individual layer thickness do not. To help understand this layer-dependent response, a crystal plasticity model is presented in which the Cu and Nb phases respond by slip on {l_brace}111{r_brace}/<110> systems in the fcc Cu case, and {l_brace}110{r_brace} / <111 > systems in the bcc Nb phase. Grains within each layered phase are required to plastically deform by a reduction in thickness and corresponding elongation in the rolling direction, with zero plastic strain along the transverse axis. The model also adopts the observation for nano-scale multilayers that the Kudjumov-Sachs orientation relation is preserved; in particular, the e 1 11> Cu and e1 10> Nb directions remain parallel to the interface normal during rolling. The crystal plasticity model then furnishes the minimum plastic work to deform a grain, as a function of grain orientation. For Cu grains, the plastic work is invariant of grain orientation, provided the critical resolved shear stress is uniform on all fcc slip systems. However, the corresponding plastic work in Nb grains is very dependent on grain orientation and has a strong minimum. This large anisotropy serves as a driving force for Nb grains to rotate around their <110> interface normal, toward the minimum. The resulting prediction for rolling texture in Nb layers agrees well with experimental observations in nanoscale Cu/Nb multilayers.

Misra, A. (Amit); Hirth, John Price,; Anderson, P. M. (Peter M.)

2002-01-01

136

Biosafe Nanoscale Pharmaceutical Adjuvant Materials  

PubMed Central

Thanks to developments in the field of nanotechnology over the past decades, more and more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research. Nanomaterials possess unique properties which could be employed to develop drug carriers with longer circulation time, higher loading capacity, better stability in physiological conditions, controlled drug release, and targeted drug delivery. In this review article, we will review recent progress in the application of representative organic, inorganic and hybrid biosafe nanoscale materials in pharmaceutical research, especially focusing on nanomaterial-based novel drug delivery systems. In addition, we briefly discuss the advantages and notable functions that make these nanomaterials suitable for the design of new medicines; the biosafety of each material discussed in this article is also highlighted to provide a comprehensive understanding of their adjuvant attributes.

Jin, Shubin; Li, Shengliang; Wang, Chongxi; Liu, Juan; Yang, Xiaolong; Wang, Paul C.; Zhang, Xin; Liang, Xing-Jie

2014-01-01

137

Systems engineering at the nanoscale  

NASA Astrophysics Data System (ADS)

Nanomaterials have provided some of the greatest leaps in technology over the past twenty years, but their relatively early stage of maturity presents challenges for their incorporation into engineered systems. Perhaps even more challenging is the fact that the underlying physics at the nanoscale often run counter to our physical intuition. The current state of nanotechnology today includes nanoscale materials and devices developed to function as components of systems, as well as theoretical visions for "nanosystems," which are systems in which all components are based on nanotechnology. Although examples will be given to show that nanomaterials have indeed matured into applications in medical, space, and military systems, no complete nanosystem has yet been realized. This discussion will therefore focus on systems in which nanotechnology plays a central role. Using self-assembled magnetic artificial cilia as an example, we will discuss how systems engineering concepts apply to nanotechnology.

Benkoski, Jason J.; Breidenich, Jennifer L.; Wei, Michael C.; Clatterbaughi, Guy V.; Keng, Pei Yuin; Pyun, Jeffrey

2012-06-01

138

Through-focus EUV multilayer defect repair with nanomachining  

NASA Astrophysics Data System (ADS)

Defects within the multilayer mirrors of EUV photomasks have been a leading challenge for EUV lithography for quite some time. By creating non-planar surfaces, they distort both the amplitude and phase of reflected light. Amplitude errors generally create a CD error on wafer, whereas phase errors tend to cause asymmetric printing through focus. Since defect-free mask blanks are not expected to be available for initial high volume EUV manufacturing, defect mitigation, compensation, and repair strategies are essential. This paper describes a technique to repair both the amplitude and phase effects of multilayer defects. For a bump defect, the phase effect (i.e. tilted Bossung curve behavior) is corrected by removing multilayer material in the vicinity of the defect. This creates a phase effect opposite to that of the defect and the two effects cancel. The amplitude error (i.e. CD error) caused by both the defect and by the phase repair is then corrected by modifying the surrounding absorber pattern. The repairs in this paper are performed by nanomachining with an AFM repair tool. The concept is validated by a combination of simulation and experimental studies with data from the Actinic Inspection Tool (AIT) at the Lawrence Berkeley National Laboratories, the EUV Alpha Demo Tool (ADT) in Albany, New York, and an AFM repair tool. The process for a complete multilayer repair is described using an example native defect repair. Encouraging results indicate that nanomachining is capable of creating the complex nano-scale three dimensional topographies required for the repair. Repair strategies for both bump and pit defects are addressed. Multiple simulation studies are used to understand the requirements for such a repair and what type of repairs may be possible.

McIntyre, Gregory; Gallagher, Emily; Robinson, Tod; Smith, Adam C.; Lawliss, Mark; LeClaire, Jeffrey; Bozak, Ron; White, Roy; Archuletta, Michael

2013-04-01

139

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

140

Ultrasonic NDE of Multilayered Structures  

SciTech Connect

This project developed ultrasonic nondestructive evaluation techniques based on guided and bulk waves in multilayered structures using arrays. First, a guided wave technique was developed by preferentially exciting dominant modes with energy in the layer of interest via an ultrasonic array. Second, a bulk wave technique uses Fermat's principle of least time as well as wave-based properties to reconstruct array data and image the multilayered structure. The guided wave technique enables the inspection of inaccessible areas of a multilayered structure without disassembling it. Guided waves propagate using the multilayer as a waveguide into the inaccessible areas from an accessible position. Inspecting multi-layered structures with a guided wave relies on exciting modes with sufficient energy in the layer of interest. Multilayered structures are modeled to determine the possible modes and their distribution of energy across the thickness. Suitable modes were determined and excited by designing arrays with the proper element spacing and frequency. Bulk wave imaging algorithms were developed to overcome the difficulties of multiple reflections and refractions at interfaces. Reconstruction algorithms were developed to detect and localize flaws. A bent-ray algorithm incorporates Fermat's principle to correct time delays in the ultrasonic data that result from the difference in wave speeds in each layer and refractions at the interfaces. A planar wave-based algorithm was developed using the Green function for the multilayer structure to enhance focusing on reception for improved imaging.

Quarry, M J; Fisher, K A; Lehman, S K

2005-02-14

141

Computational modelling of constrained sintering in EB-PVD thermal barrier coatings  

NASA Astrophysics Data System (ADS)

A micromechanical model is developed to simulate the evolution of microstructure during in-service sintering and eventual inter-columnar cracking in coatings made using electron beam vapour deposition (EB-PVD) route. The coating is idealized with a discrete distribution of axisymmetric asperities across interfaces between columnar grains. The model assumes that inter-columnar sintering is driven by changes in interface free energy of columns and the potential energy of the applied stress. Much faster diffusion that occurs over the free surfaces of the asperities is neglected. It is further assumed that the rate of sintering of the contacting asperities is determined by diffusion along the interface between the contacting asperities. Time evolution of contact modulus of the coating is accounted for as a function of sintering strain. The developed macroscopic constitutive model is employed to evaluate the sensitivity of the sintering response to imperfections and examine the conditions under which inter-columnar cracks can develop within the coating.

Kumar, S.; Cocks, A. C. F.

2013-09-01

142

Diffusion bonding of CMSX-4 to UDIMET 720 using PVD-coated interfaces and HIP  

SciTech Connect

There is an increasing interest in development of manufacturing methods for Dual Property BLISKs (BLaded dISKs), consisting of creep resistant airfoils and fatigue resistant disks bonded together by a durable joint. Optimum heat treatments are, however, very different for creep resistant single crystal CMSX-4 and fatigue resistant polycrystalline Udimet 720 selected in this study, but fortunately the first aging treatment for CMSX-4 (1140 C, 2-6h, AC) is similar to the partial solution treatment of U 720 HS2 (1115 C, 4h, OQ). Based on this, diffusion bonding was performed by HIP at 1120 C and 200 MPa argon pressure for 4 h, followed by cooling to 400 C. Subsequently, a shortened Udimet 720 HS2 two-step aging treatment was adopted by heating to 650 C for 6 h followed by cooling to 400 C, heating to 760 C for 2 h, and finally cooling to R.T. under remaining HIP pressure. Plasma etching followed by thin (80 nm) PVD coating with either nickel or titanium were used to clean and protect the polished surfaces before joining. The selection of coatings was governed by the possibility to reduce oxidized nickel by flushing with hydrogen at 330 C during evacuation of the HIP capsules, and by the large solubility of oxygen in titanium. Hot tensile testing was performed at 750 C on both joined and reference materials subjected to the modified heat treatment. Initially solution treated Udimet 720 and CMSX-4 comprised the reference materials. The testing showed that joints with Ni-PV coatings were almost as strong as Udimet 720 (although with very limited elongation), while the joints with Ti-PVD coatings were weaker.

Larker, R. [Lulea Univ. of Technology (Sweden). Div. of Engineering Materials; Ockborn, J.; Selling, B. [Volvo Aero Corp., Trollhattan (Sweden)

1999-07-01

143

Multilayer coatings on flexible substrates  

SciTech Connect

Thin-film optical and non-optical multilayer coatings are deposited onto flexible substrates using a vacuum web coater developed at Pacific Northwest Laboratory. The coater`s primary application is rapid prototyping of multilayer (1) polymer coatings, (2) polymer/metal coatings, (3) ceramic/metal coatings, and (4) hybrid polymer, ceramic, and metal coatings. The coater is fully automated and incorporates polymer evaporation and extrusion heads, high-rate magnetron sputtering cathodes, and e-beam evaporation sources. Polymer electrolytes are deposited by extrusion techniques. Flexible plastic, metal, and ceramic substrates can be coated using roll-to-roll or closed-loop configurations. Examples of multilayer optical coatings demonstrated to date are solar reflectors, heat mirrors, Fabry-Perot filters, and alpha particle sensors. Nonoptical coatings include multilayer magnetic metal/ceramic and lamellar composites.

Martin, P.M.; Affinito, J.D.; Gross, M.E.; Coronado, C.A.; Bennett, W.D.; Stewart, D.C.

1995-04-01

144

Computing and fabricating multilayer models  

Microsoft Academic Search

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 and cheaply and provide a strong sense of an object's 3D shape and texture over a wide range of viewing directions. Our method is designed to minimize

Michael Holroyd; Ilya Baran; Jason Lawrence; Wojciech Matusik

2011-01-01

145

Artificial multilayers and nanomagnetic materials  

PubMed Central

The author has been actively engaged in research on nanomagnetic materials for about 50 years. Nanomagnetic materials are comprised of ferromagnetic systems for which the size and shape are controlled on a nanometer scale. Typical examples are ultrafine particles, ultrathin films, multilayered films and nano-patterned films. In this article, the following four areas of the author’s studies are described. (1) Mössbauer spectroscopic studies of nanomagnetic materials and interface magnetism. (2) Preparation and characterization of metallic multilayers with artificial superstructures. (3) Giant magnetoresistance (GMR) effect in magnetic multilayers. (4) Novel properties of nanostructured ferromagnetic thin films (dots and wires). A subject of particular interest in the author’s research was the artificially prepared multilayers consisting of metallic elements. The motivation to initiate the multilayer investigation is described and the physical properties observed in the artificial multilayers are introduced. The author’s research was initially in the field of pure physical science and gradually extended into applied science. His achievements are highly regarded not only from the fundamental point of view but also from the technological viewpoint. PMID:23391605

SHINJO, Teruya

2013-01-01

146

SI System and Nanoscale Science  

NSDL National Science Digital Library

This lesson, presented by the National Nanotechnology Infrastructure Network, covers the metric system. Students will explore the use of the metric system in the activities, and also "read the How Stuff Works article –“How Nanotechnology Works” and answer questions about the article. Further connections of size and the nanoscale can be found in the Resources at the end of the unit."  This activity will take two 50 minute classroom sessions. Two Teacher Preparation Guides and Student Guides are included. 

2014-08-14

147

Structural and chemical investigations of CBD and PVD-CdS buffer layers and interfaces in Cu(In,Ga)Se 2-based thin film solar cells  

Microsoft Academic Search

It is known that high-efficiency thin film solar cells based on Cu(In,Ga)Se2 (CIGS) can be obtained using CdS buffer layers grown by chemical bath deposition (CBD). The highest efficiencies achieved with CdS buffer layers produced by physical vapor deposition (PVD) are significantly lower. To find reasons for this difference, structural and chemical properties of CBD- and PVD-CdS buffer layers and

D. Abouras; G. Kostorz; A. Romeo; D. Rudmann; A. N. Tiwari

2005-01-01

148

Photoresponsive nanoscale columnar transistors Xuefeng Guoa,1  

E-print Network

Photoresponsive nanoscale columnar transistors Xuefeng Guoa,1 , Shengxiong Xiaob , Matthew Myersb reports a general methodology for making stable high-performance photosensitive field effect transistors nanostructures with a diameter similar to that of SWNTs and then form nanoscale columnar transistors. To rule out

Hone, James

149

A nanoscale shape memory oxide.  

PubMed

Stimulus-responsive shape-memory materials have attracted tremendous research interests recently, with much effort focused on improving their mechanical actuation. Driven by the needs of nanoelectromechanical devices, materials with large mechanical strain, particularly at nanoscale level, are therefore desired. Here we report on the discovery of a large shape-memory effect in bismuth ferrite at the nanoscale. A maximum strain of up to ~14% and a large volumetric work density of ~600±90?J?cm(-3) can be achieved in association with a martensitic-like phase transformation. With a single step, control of the phase transformation by thermal activation or electric field has been reversibly achieved without the assistance of external recovery stress. Although aspects such as hysteresis, microcracking and so on have to be taken into consideration for real devices, the large shape-memory effect in this oxide surpasses most alloys and, therefore, demonstrates itself as an extraordinary material for potential use in state-of-art nanosystems. PMID:24253399

Zhang, Jinxing; Ke, Xiaoxing; Gou, Gaoyang; Seidel, Jan; Xiang, Bin; Yu, Pu; Liang, Wen-I; Minor, Andrew M; Chu, Ying-Hao; Van Tendeloo, Gustaaf; Ren, Xiaobing; Ramesh, Ramamoorthy

2013-01-01

150

A nanoscale shape memory oxide  

NASA Astrophysics Data System (ADS)

Stimulus-responsive shape-memory materials have attracted tremendous research interests recently, with much effort focused on improving their mechanical actuation. Driven by the needs of nanoelectromechanical devices, materials with large mechanical strain, particularly at nanoscale level, are therefore desired. Here we report on the discovery of a large shape-memory effect in bismuth ferrite at the nanoscale. A maximum strain of up to ~14% and a large volumetric work density of ~600±90?J?cm-3 can be achieved in association with a martensitic-like phase transformation. With a single step, control of the phase transformation by thermal activation or electric field has been reversibly achieved without the assistance of external recovery stress. Although aspects such as hysteresis, microcracking and so on have to be taken into consideration for real devices, the large shape-memory effect in this oxide surpasses most alloys and, therefore, demonstrates itself as an extraordinary material for potential use in state-of-art nanosystems.

Zhang, Jinxing; Ke, Xiaoxing; Gou, Gaoyang; Seidel, Jan; Xiang, Bin; Yu, Pu; Liang, Wen-I.; Minor, Andrew M.; Chu, Ying-Hao; van Tendeloo, Gustaaf; Ren, Xiaobing; Ramesh, Ramamoorthy

2013-11-01

151

HRTEM and EELS studies of nanoscale structured electronic materials  

NASA Astrophysics Data System (ADS)

This thesis focuses on the growth and structure of a number of nanoscale structured electronic materials characterized using HRTEM and EELS. Both rare earth silicide nanostructures self-assembled on Si(001) and sputtered GMR multilayers have been studied by characterizing their crystal structures, interfacial epitaxy, interfacial chemical nature, and electronic nature, which provide fundamental insights into material behavior at the nanometer scale. High aspect ratio nanowires and nanosized islands have been observed to self-assemble on Si(001) for both the Gd and Tm silicide systems. HRTEM results show that Gd silicide nanostructures exhibit either the hexagonal GdSi 2-x or the orthorhombic GdSi2 crystal structures, with lattice parameters consistent with the bulk phases. In the case of Tm, the observed nanostructures are likewise either hexagonal or orthorhombic. The hexagonal phase has lattice parameters consistent with the bulk, while the orthorhombic does not. For both systems, bi-phasic silicide structures were observed, which may reflect a mechanism for strain accommodation at the interface with the substrate. In the case of Gd, the phase with lower strain lies at the substrate. For the case of Tm, the relative mismatches of the two phases predicted from bulk silicide lattice parameters disagree with that derived from measured lattice constants, and it is a relaxed orthorhombic phase at the interface that appears to have the lowest mismatch with the substrate. EELS studies were carried out to compare the electronic structures of metallic Gd, thin film Gd silicide, and Gd oxide in bulk phases and Gd silicide nanostructures. The results from the three bulk phases are similar, while the intensity ratio of M5:M4 in the GdSi2 nanostructures varies from the bulk, which may suggest that a slightly different spin state exists in the silicide nanostructures. As-sputtered and annealed F(Co, or Py)/Al multilayers have been studied using HRTEM and EELS. Although the interfacial intensity profiles from EELS spectrum images suggest some limited intermixing exists in the F/Al interfacial regions, both HRTEM and diffraction studies show no obvious intermediate phase formation. In particular, the annealing treatments do not significantly alter the multilayer structures. In contrast, intermediate phase formation has been observed in both Cu/Al multilayers and Cu/Al regions in spin valves. Tetragonal Al2Cu and bcc AlCu3 are formed in the Cu(8nm)/Al(10nm) multilayers, while Al2Cu and fcc Cu are formed in the Cu(5nm)/Al(3nm) multilayers. For Cu/Al/Cu layers in the spin-valves, evidence of Al2 Cu and AlCu3 phase formation in the annealed spin-valve with the 30nm Al layer was found, while Al2Cu and Cu were observed in the as-sputtered spin-vale with the 10nm Al layer. These results are discussed in terms of the balance between interfacial and plume free energies in order to rationalize the formation of non-equilibrium structures.

Zhang, Jiaming

152

Improvement of EB-PVD thermal barrier coatings by treatments of a vacuum plasma-sprayed bond coat  

Microsoft Academic Search

The lifetime of electron beam physical vapor deposited (EB-PVD) thermal barrier coating (TBC) systems with conventional 7 YSZ ceramic top layers was investigated in 1 h thermal-cyclic testing at 1100 °C. The single crystal alloy CMSX-4 and the polycrystalline IN 100 alloy that had been coated with a vacuum plasma-sprayed MCrAlY bond coat were chosen as substrate materials. A fully plasma-sprayed TBC

U. Schulz; O. Bernardi; A. Ebach-Stahl; R. Vassen; D. Sebold

2008-01-01

153

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

154

Microstructural analyses and wear behavior of the cemented carbide tools after laser surface treatment and PVD coating  

NASA Astrophysics Data System (ADS)

Adhesion is one of the most important characteristics of coating on cutting tools. Poor coating adhesion on the tool favors fragmentation and release of hard abrasive particles between the tool and the workpiece. These particles interact with the surfaces of the tool, accelerating its wear and decreasing tool life. One possible solution is the use of laser texturing prior to coating in order to achieve a desired surface topography with enhanced adhesion properties. In the texturing, a high-frequency short-pulse laser changes surface characteristics, generating resolidified material and selective vaporization. This work evaluated the effectiveness of laser texturing in improving the substrate-coating adhesion of PVD coated cemented carbide tools. To this end, the substrates were textured with a Nd:YAG laser, in four different intensities, and then coated with a PVD TiAlN film. To ascertain the effectiveness of laser texturing, Rockwell C indentation and turning experiments were performed on both textured tools and conventional unlasered tools. The PVD coated laser-textured tool showed better performance in the indentation and turning tests than the standard tools. A comparative evaluation of tool wear mechanisms indicated that texturing did not change the wear mechanisms, but altered their importance to tool wear. The anchoring provided by the higher roughness of the textured surface increased the adhesion of the coating on the substrate, thus increasing tool life. Additionally, the chemical modification of the carbide grains due to the laser heating might be responsible for an enhanced adhesion between coating and substrate.

Neves, Davi; Diniz, Anselmo Eduardo; Lima, Milton Sérgio Fernandes

2013-10-01

155

Blending effect of poly (ethyl methacrylate) on lithium bis(perfluoroethanesulfonyl) imide-ferroceramic PVdF-HFP composite  

NASA Astrophysics Data System (ADS)

PEMA as a supportive host matrix is physically blended in five different proportions with PVdF-HFP based system containing LiBETI as a electrolyte, EC / DMC mixture in 1:1 v/v ratio as a plasticizer and BaTiO3 as a filler for improving ionic conductivity is attempted. The A.C impedance, DSC, and FTIR studies are carried out. The ionic conductivity measurements on these Polymer Blend Nano Composites(PBNC) showed that blending improved ionic conductivity, and enhancement in magnitude is observed for 22.5% PEMA blended PVdF-HFP (7.5 wt%) system with 7.5% BaTiO3. The DSC showed PEMA interaction with PVDF causing reorientation of VDF crystals and resulting conformational changes showed variations in melting endotherms, are observed. FTIR studies identified PEMA interaction with plasticizer and PVdF-HFP through the change in the C-F stretching and C=O Carbonyl bond.

Vickraman, P.; Jayaraman, R.; Purushothaman, K.

2013-06-01

156

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

157

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

158

Design and fabrication of heat resistant multilayers  

SciTech Connect

Many promising applications of multilayer x-ray optical elements subject them to intense radiation. This paper discusses the selection of optimal pairs of materials to resist heat damage and presents simulations of multilayer performance under extreme heat loadings.

Thorne, J.M.; Knight, L.V.; Peterson, B.G.; Perkins, R.T.; Gray, K.J.

1986-01-01

159

Simplified methods of modeling multilayer reservoirs  

E-print Network

The purpose of this study is to develop simplified methods to model multilayer reservoirs. We examined the method to model well responses of multilayer reservoirs with equivalent single layer solutions during transient flow period which Bennett...

Ryou, Sangsoo

2012-06-07

160

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

161

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

162

Optical transmittance of multilayer graphene  

NASA Astrophysics Data System (ADS)

We study the optical transmittance of multilayer graphene films up to 65 layers thick. By combing large-scale tight-binding simulation and optical measurement on CVD multilayer graphene, the optical transmission through graphene films in the visible region is found to be solely determined by the number of graphene layers. We argue that the optical transmittance measurement is more reliable in the determination of the number of layers than the commonly used the Raman spectroscopy. Moreover, the optical transmittance measurement can be applied also to other 2D materials with weak van der Waals interlayer interaction.

Zhu, Shou-En; Yuan, Shengjun; Janssen, G. C. A. M.

2014-10-01

163

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

164

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

165

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

166

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

167

Ga(+) beam lithography for nanoscale silicon reactive ion etching.  

PubMed

By using a dry etch chemistry which relies on the highly preferential etching of silicon, over that of gallium (Ga), we show resist-free fabrication of precision, high aspect ratio nanostructures and microstructures in silicon using a focused ion beam (FIB) and an inductively coupled plasma reactive ion etcher (ICP-RIE). Silicon etch masks are patterned via Ga(+) ion implantation in a FIB and then anisotropically etched in an ICP-RIE using fluorinated etch chemistries. We determine the critical areal density of the implanted Ga layer in silicon required to achieve a desired etch depth for both a Pseudo Bosch (SF(6)/C(4)F(8)) and cryogenic fluorine (SF(6)/O(2)) silicon etching. High fidelity nanoscale structures down to 30 nm and high aspect ratio structures of 17:1 are demonstrated. Since etch masks may be patterned on uneven surfaces, we utilize this lithography to create multilayer structures in silicon. The linear selectivity versus implanted Ga density enables grayscale lithography. Limits on the ultimate resolution and selectivity of Ga lithography are also discussed. PMID:20484788

Henry, M D; Shearn, M J; Chhim, B; Scherer, A

2010-06-18

168

Dynamics of sliding mechanisms in nanoscale friction  

E-print Network

Nanotribology is the study of friction and wear at the nanoscale, with relevance to such applications as micromechanical systems (MEMS) and thin, hard coatings. For these systems, classical laws of friction are inappropriate ...

Yim, Shon W., 1973-

2002-01-01

169

Ultra-thin Multilayer Capacitors.  

National Technical Information Service (NTIS)

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 Laborat...

T. C. Monson, T. J. Renk

2009-01-01

170

Multilayer thermionic refrigerator and generator  

Microsoft Academic Search

A new method of refrigeration is proposed. Cooling is obtained by thermionic emission of electrons over periodic barriers in a multilayer geometry. These could be either Schottky barriers between metals and semiconductors or else barriers in a semiconductor superlattice. The same device is an efficient power generator. A complete theory is provided.

G. D. Mahan; J. O. Sofo; M. Bartkowiak

1998-01-01

171

Polarization coupling in ferroelectric multilayers  

NASA Astrophysics Data System (ADS)

A thermodynamic model was developed to understand the role of charge compensation at the interlayer interfaces in compositionally graded monodomain ferroelectric multilayers. The polarization mismatch between the ferroelectric layers generates depoling fields with the polarization in each layer varying from its bulk uncoupled value as to adapt to the electrical boundary conditions. By treating the strength of the electrostatic field as a phenomenological parameter, it is shown that if there are localized charges to compensate for the polarization mismatch and relax the depolarization fields, ferroelectric layers behave independently of each other and exhibit a dielectric response that can be described as the sum of their corresponding intrinsic uncoupled dielectric properties. For perfectly insulating heterostructures with no localized charges, the depolarization field is minimized by lowering the polarization difference between layers, yielding a ferroelectric multilayer that behaves as if it were a single ferroelectric material. There exists an optimum value of coupling strength at which average polarization of the multilayer is maximized. Furthermore, ferroelectric multilayers may display a colossal dielectric response dependant upon the interlayer electrostatic interactions.

Okatan, M. B.; Mantese, J. V.; Alpay, S. P.

2009-05-01

172

Multilayer infrared beamsplitter film system  

NASA Technical Reports Server (NTRS)

Multilayer infrared beamsplitter film system on a potassium bromide crystal substrate is operational over a wavelength range of 2.5 to 25 microns with nearly equal broadband reflectance and transmittance. It is useful in optical coating, vacuum deposition, radiometry, interferometry, and spectrometry.

Bastien, R. C.; Heinrich, P. L.

1969-01-01

173

Impact properties of multilayered materials  

Microsoft Academic Search

The possibilities of multilayered materials as high impact resistance materials are considered with reference to safety in transportation. The mechanism of fracture of the different layers of the material produces an enhancement of the impact resistance behavior and, as a consequence, a lower quantity of material is needed with the corresponding saving in weight of the transport vehicle. The reinforcing

A. J. VAZQUEZ VAAMONDE

1993-01-01

174

Asymmetric growth in polyelectrolyte multilayers.  

PubMed

Radioactive counterions were used to track the ratio of positive to negative polymer repeat units within a polyelectrolyte multilayer made from poly(diallyldimethylammonium chloride), PDADMAC, and poly(styrene sulfonate), PSS. For this widely employed pair of "linearly" assembled polyelectrolytes it was found that the accepted model of charge overcompensation for each layer is incorrect. In fact, overcompensation at the surface occurs only on the addition of the polycation, whereas PSS merely compensates the PDADMAC. After the assembly of about a dozen layers, excess positive sites begin to accrue in the multilayer. Treating the surface as a reaction-diffusion region for pairing of polymer charges, a model profile was constructed. It is shown that different reaction-diffusion ranges of positive and negative polyelectrolyte charge lead to a blanket of glassy, stoichiometric complex growing on top of a layer of rubbery, PDADMAC-rich complex. Though overcompensation and growth was highly asymmetric with respect to the layer number, entirely conventional "linear" assembly of the multilayer was observed. The impact of asymmetric growth on various properties of multilayers is discussed. PMID:23672490

Ghostine, Ramy A; Markarian, Marie Z; Schlenoff, Joseph B

2013-05-22

175

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

176

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

177

Structural transitions in nanoscale systems  

NASA Astrophysics Data System (ADS)

In this work I investigate three different materials: nanoscale carbon systems, ferrofluid systems, and molecular-electronic devices. In particular, my study is focused on the theoretical understanding of structural changes and the associated electronic, mechanical, and magnetic properties of these materials. To study the equilibrium packing of fullerenes in carbon nanotube peapods optimization techniques were applied. In agreement with experimental measurements, my results for nanotubes containing fullerenes with 60--84 atoms indicate that the axial separation between the fullerenes is smaller than in the bulk crystal. The reduction of the inter-fullerene distance and also the structural relaxation of fullerenes result from a large internal pressure within the peapods. This naturally induced "static" pressure may qualify nanotubes as nanoscale autoclaves for chemical reactions. Combining total energy calculations with a search of phase space, I investigated the microscopic fusion mechanism of C60 fullerenes. I show that the (2+2) cycloaddition reaction, a necessary precursor for fullerene fusion, can be accelerated inside a nanotube. Fusion occurs along the minimum energy path as a finite sequence of Stone-Wales (SW) transformations. A detailed analysis of the transition states shows that Stone-Wales transformations are multi-step processes. I propose a new microscopic mechanism to explain the unusually fast fusion process of carbon nanotubes. The detailed pathway for two adjacent (5, 5) nanotubes to gradually merge into a (10, 10) tube, and the transition states have been identified. The propagation of the fused region is energetically favorable and proceeds in a morphology reminiscent of a Y-junction via a so called zipper mechanism, involving only SW bond rearrangements with low activation barriers. Using density functional theory, the equilibrium structure, stability, and electronic properties of nanostructured, hydrogen terminated diamond fragments have been studied. Such diamondoids can enter spontaneously into carbon nanotubes where polymerization of diamondoids is favourable. I studied the equilibrium structure of large but finite aggregates of magnetic dipoles, modeling a colloidal suspension of magnetite particles in a ferrofluid. With increasing system size, the structural motif evolves from chains and rings to multi-chain and multi-ring assemblies. These structural changes depend on external parameters and result from a competition between various energy terms, which can be described analytically within a continuum approximation. (Abstract shortened by UMI.)

Yoon, Mina

178

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

179

Magnetic Alloys in Nanoscale Biomaterials  

SciTech Connect

Fe-Co composition gradient and Fe-Pt multilayer alloy films were tested as catalysts for growing vertically aligned carbon nanofibers (VACNFs) by plasma-enhanced chemical vapor deposition (PECVD). The Fe-Co film yielded nanofibers with alloy tips in a wide compositional range varying from 8.15 pct Fe at the Co-rich end to 46.29 pct Fe in the middle of the wafer as determined by energy-dispersive X-ray analysis. Two Fe-Co cubic phases (SG Pm3m, Pm{bar 3}m) were identified by preliminary X-ray diffraction (XRD) measurements. Magnetic measurements showed a substantially greater hysteresis loop area and coercivity in Fe-Co catalyst nanoparticles as compared to the as deposited Fe-Co film. The Fe-Pt film did not break into FePt alloy nanoparticles under the applied processing parameters and thus the utility of FePt as a VACNF catalyst has been inconclusive.

Leventouri, T. H. [Florida Atlantic University; Melechko, Anatoli Vasilievich [ORNL; Sorge, Korey D. [Florida Atlantic University; Klein, Kate L [ORNL; Fowlkes, Jason Davidson [ORNL; Rack, P. D. [University of Tennessee, Knoxville (UTK); Anderson, Ian M [ORNL; Thompson, James R [ORNL; McKnight, Timothy E [ORNL; Simpson, Michael L [ORNL

2006-01-01

180

Mechanics of nanoscale metallic multilayers: From atomic-scale to micro-scale  

Microsoft Academic Search

Layered composites of Cu\\/Nb with incoherent interfaces achieve very high strength levels. Interfaces play a crucial role in determining this strength by acting as barriers to slip. Atomistic models of Cu\\/Nb bilayers are used to explore the origins of this resistance. The models clearly show that dislocations near an interface experience an attraction toward the interface. This attraction is caused

J. Wang; R. G. Hoagland; A. Misra

2009-01-01

181

Characterization of PVdF-HFP polymer membranes prepared by phase inversion techniques I. Morphology and charge–discharge studies  

Microsoft Academic Search

A novel nanoporous polymer membrane comprised of poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by phase inversion techniques using two different non-solvents. The films were subjected to scanning electron microscope (SEM) and nitrogen adsorption\\/desorption analysis. The morphology and porosity of the membranes are correlated with the chemical structure of the non-solvents used. Also, nanoparticle LiCr0.01Mn1.99O4 cathode material was prepared by solid-state

A. Manuel Stephan; Dale Teeters

2003-01-01

182

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

183

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

184

Casting Of Multilayer Ceramic Tapes  

NASA Technical Reports Server (NTRS)

Procedure for casting thin, multilayer ceramic membranes, commonly called tapes, involves centrifugal casting at accelerations of 1,800 to 2,000 times normal gravitational acceleration. Layers of tape cast one at a time on top of any previous layer or layers. Each layer cast from slurry of ground ceramic suspended in mixture of solvents, binders, and other components. Used in capacitors, fuel cells, and electrolytic separation of oxygen from air.

Collins, Earl R., Jr.

1991-01-01

185

EB-PVD Y 2O 3- and CeO 2 Y 2O 3 -stabilized zirconia thermal barrier coatings — crystal habit and phase composition  

Microsoft Academic Search

ZrO2-based ingot sources with stabilizing oxides of 6.5 and 20 wt.% Y2O3 and 252.5 wt.% CeO2Y2O3 respectively were used to deposit thermal barrier coatings (TBCs) on rotating cylindrical electron beam physical vapour deposition (EB-PVD) NiCoCrAlY-coated IN 100 substrates by reactive high rate EB-PVD. The TBCs were investigated by scanning electron microscopy, X-ray fluorescence and X-ray diffraction. The phases within the

U. Schulz; K. Fritscher; M. Peters

1996-01-01

186

Multilayered Transducers Using Polyurea Film  

NASA Astrophysics Data System (ADS)

We have been investigating ultrasonic transducers using a polyurea piezoelectric material, which is fabricated by vapor deposition. To enhance the transducer performance, a multilayered configuration is studied in this work. First, the fabrication and transducer design of the multilayered structure are described. A special twin-vacuum chamber is used for laminating the polyurea layers and aluminum electrodes alternately without breaking vacuum. We fabricate two- and four-layered transducers with 1.5 ?m polyurea films. The calculation results show that the force factor and electromechanical coupling coefficient increase as the number of layers increases. Second, to evaluate the transducer performance, we measure the electromechanical coupling factors and electric admittances. The coupling coefficients also increase as the number of layers increases at the resonant frequencies of about 30, 65, and 100 MHz. The pulse/echo measurements are conducted to determine the transmission and receiving characteristics using a reflector. The results of the experiment show that the voltage amplitudes of the received signal increase because of multilayer lamination.

Nakazawa, Marie; Tabaru, Masaya; Nakamura, Kentaro; Ueha, Sadayuki; Maezawa, Akihiro

2007-07-01

187

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

188

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

189

Multilayer Analysis and Visualization of Networks  

E-print Network

Multilayer relationships among and information about biological entities must be accompanied by the means to analyze, visualize, and obtain insights from such data. We report a methodology and a collection of algorithms for the analysis of multilayer networks in our new open-source software (muxViz). We demonstrate the ability of muxViz to analyze and interactively visualize multilayer data using empirical genetic and neuronal networks.

De Domenico, Manlio; Arenas, Alex

2014-01-01

190

Multi-layer seal for electrochemical devices  

DOEpatents

Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

2010-09-14

191

Multi-layer seal for electrochemical devices  

DOEpatents

Multi-layer seals are provided that find advantageous use for reducing leakage of gases between adjacent components of electrochemical devices. Multi-layer seals of the invention include a gasket body defining first and second opposing surfaces and a compliant interlayer positioned adjacent each of the first and second surfaces. Also provided are methods for making and using the multi-layer seals, and electrochemical devices including said seals.

Chou, Yeong-Shyung [Richland, WA; Meinhardt, Kerry D [Kennewick, WA; Stevenson, Jeffry W [Richland, WA

2010-11-16

192

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

193

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

194

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

195

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

196

Bench-scale synthesis of nanoscale materials  

SciTech Connect

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), combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was demonstrated on a laboratory scale and 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 m{sup 2}/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO{sub 2} produced by RTDS are included.

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

1993-12-01

197

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

198

Chromosome congression explained by nanoscale electrostatics  

PubMed Central

Nanoscale electrostatic microtubule disassembly forces between positively charged molecules in kinetochores and negative charges on plus ends of microtubules have been implicated in poleward chromosome motions and may also contribute to antipoleward chromosome movements. We propose that chromosome congression can be understood in terms of antipoleward nanoscale electrostatic microtubule assembly forces between negatively charged microtubule plus ends and like-charged chromosome arms, acting in conjunction with poleward microtubule disassembly forces. Several other aspects of post-attachment prometaphase chromosome motions, as well as metaphase oscillations, are consistently explained within this framework. PMID:24564840

2014-01-01

199

Fault-Tolerant Nanoscale Processors on Semiconductor Nanowire Grids  

Microsoft Academic Search

Nanoscale processor designs pose new challenges not encountered in the world of conventional CMOS designs and manufacturing. Nanoscale devices based on crossed semiconductor nanowires (NWs) have promising characteristics in addition to providing great density advantage over conventional CMOS devices. This density advantage could, however, be easily lost when assembled into nanoscale systems and especially after techniques dealing with high defect

Csaba Andras Moritz; Teng Wang; Pritish Narayanan; Michael Leuchtenburg; Yao Guo; Catherine Dezan; Mahmoud Bennaser

2007-01-01

200

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

201

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

202

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

203

Science of Nanoscale Systems and their Device Applications  

Microsoft Academic Search

The goal of our Nanoscale Science and Engineering Center is to study the fundamental properties of nanoscale structures with a view toward their possible use in new electronic and magnetic devices. Its research encompasses three areas: The Growth of Nanoscale Structures - uses approaches ranging from chemical growth of nanoparticles, to self-organized growth of patterned surfaces, to new types of

R. M. Westervelt

2003-01-01

204

2001 Annual Technical Report Nanoscale Science and Engineering Center  

E-print Network

2001 Annual Technical Report Nanoscale Science and Engineering Center For Integrated Nanopatterning 1, 2001 to February 1, 2002 of the new Nanoscale Science and Engineering Center for Integrated of the Center are primarily supported through the Nanoscale Science and Engineering Initiative of the National

Shull, Kenneth R.

205

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

206

Method of making coherent multilayer crystals  

DOEpatents

A new material consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 .ANG. to 2500 .ANG.. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

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

1984-01-01

207

Corrosion protection by multilayered conducting polymer coatings  

Microsoft Academic Search

Multilayered coatings, consisting of combinations of the conducting polymers polyaniline (Pani) and polypyrrole (Ppy), were galvanostatically deposited on to both carbon steel and stainless steel. Potentiodynamic polarisation was used to assess the ability of these copolymers to provide an effective barrier to corrosion in chloride environments. For carbon steel the performance of these multilayered coatings on carbon steel were not

C. K Tan; D. J Blackwood

2003-01-01

208

Coherent multilayer crystals and method of making  

DOEpatents

A new material is described consisting of a coherent multilayer crystal of two or more elements where each layer is composed of a single element. Each layer may vary in thickness from about 2 A to 2500 A. The multilayer crystals are prepared by sputter deposition under conditions which slow the sputtered atoms to near substrate temperatures before they contact the substrate.

Schuller, I.K.; Falco, C.M.

1980-10-30

209

Analysis and design of multilayer Jaumann absorbers  

Microsoft Academic Search

In this paper, a transmission line model is constructed to analyze the performance of radar absorbing materials and the reflection characteristic of the resonance frequency. First, the paper introduces some kind of radar absorbing materials. Then, multilayer Jaumann absorbers are also analyzed using Smith Chart. Last, some multilayer Jaumann absorbers can be designed in the paper , which have good

Li Ke; Zhang Xin; Hou Xinyu; Zhang Peng

2011-01-01

210

Nanoscale Calorimetry of Isolated Polyethylene Single Crystals  

E-print Network

Nanoscale Calorimetry of Isolated Polyethylene Single Crystals A. T. KWAN, M. YU. EFREMOV, E. A-film differential scanning calorimetry to investigate the melt- ing of isolated polyethylene single crystals: microelectromechanical systems; calorimetry; nanocalorimetry; polyeth- ylene single crystals; melting INTRODUCTION We

Allen, Leslie H.

211

Fats, Oils, & Colors of a Nanoscale Material  

ERIC Educational Resources Information Center

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…

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

2006-01-01

212

Oxygen Detection via Nanoscale Optical Indicators  

E-print Network

dissolved oxygen in the 0.2­17 mg/L range at temperatures of 10-25 °C. The sensor output was validated usingOxygen 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

Ghosh, Ruby N.

213

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

214

Nanoscale Spectroscopy and Nanotechnology 8 Scientific Program  

E-print Network

1 Nanoscale Spectroscopy and Nanotechnology 8 Scientific Program Gleacher Center Chicago, USA #12 Materials, Argonne National Laboratory, Department of Medicine, The University of Chicago USA. (Invited, and Dept. of Medicine, University of Illinois, Chicago, USA. Fabrication and characterization of smart CNT

Kemner, Ken

215

Nanoscale Thermal Transport andMicrorefrigeratorsonaChip  

E-print Network

INVITED P A P E R Nanoscale Thermal Transport andMicrorefrigeratorsonaChip Devices for cooling high. Experimental results have shown that phonon surface and interface scattering can lower thermal con- ductivity and quantum dot thermoelectrics as well as solid-state thermionic thin-film devices with embedded metallic

216

Enhanced nanoscale friction on fluorinated graphene.  

PubMed

Atomically thin graphene is an ideal model system for studying nanoscale friction due to its intrinsic two-dimensional (2D) anisotropy. Furthermore, modulating its tribological properties could be an important milestone for graphene-based micro- and nanomechanical devices. Here, we report unexpectedly enhanced nanoscale friction on chemically modified graphene and a relevant theoretical analysis associated with flexural phonons. Ultrahigh vacuum friction force microscopy measurements show that nanoscale friction on the graphene surface increases by a factor of 6 after fluorination of the surface, while the adhesion force is slightly reduced. Density functional theory calculations show that the out-of-plane bending stiffness of graphene increases up to 4-fold after fluorination. Thus, the less compliant F-graphene exhibits more friction. This indicates that the mechanics of tip-to-graphene nanoscale friction would be characteristically different from that of conventional solid-on-solid contact and would be dominated by the out-of-plane bending stiffness of the chemically modified graphene. We propose that damping via flexural phonons could be a main source for frictional energy dissipation in 2D systems such as graphene. PMID:22720882

Kwon, Sangku; Ko, Jae-Hyeon; Jeon, Ki-Joon; Kim, Yong-Hyun; Park, Jeong Young

2012-12-12

217

Luminescence and Scintillation Properties at the Nanoscale  

Microsoft Academic Search

This contribution is a review of the luminescence and scintillation properties of nanoparticles (NP), particularly doped insulators. Luminescence spectroscopy is an appropriate tool to probe matter at the nanoscale. Luminescence is also the last stage of the scintillation process. Specific surface and structural effects occurring in NP are reported. Their consequences on the NP luminescence properties are discussed. Parts of

Christophe Dujardin; David Amans; Andrei Belsky; Frederic Chaput; Gilles Ledoux; Anne Pillonnet

2010-01-01

218

Nanoscale spectroscopy and imaging of hemoglobin.  

PubMed

Sub diffraction limited infrared absorption imaging of hemoglobin was performed by coupling IR optics with an atomic force microscope. Comparisons between the AFM topography and IR absorption images of micron sized hemoglobin features are presented, along with nanoscale IR spectroscopic analysis of the metalloprotein. PMID:21374826

Kennedy, Eamonn; Yarrow, Fiona; Rice, James H

2011-09-01

219

Dynamic structural disorder in supported nanoscale catalysts  

NASA Astrophysics Data System (ADS)

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.

2014-04-01

220

Direct temperature mapping of nanoscale plasmonic devices.  

PubMed

Side by side with the great advantages of plasmonics in nanoscale light confinement, the inevitable ohmic loss results in significant joule heating in plasmonic devices. Therefore, understanding optical-induced heat generation and heat transport in integrated on-chip plasmonic devices is of major importance. Specifically, there is a need for in situ visualization of electromagnetic induced thermal energy distribution with high spatial resolution. This paper studies the heat distribution in silicon plasmonic nanotips. Light is coupled to the plasmonic nanotips from a silicon nanowaveguide that is integrated with the tip on chip. Heat is generated by light absorption in the metal surrounding the silicon nanotip. The steady-state thermal distribution is studied numerically and measured experimentally using the approach of scanning thermal microscopy. It is shown that following the nanoscale heat generation by a 10 mW light source within a silicon photonic waveguide the temperature in the region of the nanotip is increased by ? 15 °C compared with the ambient temperature. Furthermore, we also perform a numerical study of the dynamics of the heat transport. Given the nanoscale dimensions of the structure, significant heating is expected to occur within the time frame of picoseconds. The capability of measuring temperature distribution of plasmonic structures at the nanoscale is shown to be a powerful tool and may be used in future applications related to thermal plasmonic applications such as control heating of liquids, thermal photovoltaic, nanochemistry, medicine, heat-assisted magnetic memories, and nanolithography. PMID:24422562

Desiatov, Boris; Goykhman, Ilya; Levy, Uriel

2014-02-12

221

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

222

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

223

Nanoscale precipitation in hot rolled sheet steel  

NASA Astrophysics Data System (ADS)

Some newer hot rolled high strength low alloy (HSLA) steels with a single phase ferrite matrix have obtained substantial strengthening from nanoscale precipitation. These HSLA are reported to have a good combination of strength, ductility and hole-expansion ability. In the current work, Gleeble ® 3500 torsion testing was employed to simulate the hot rolling process with varying run-out table cooling rates and coiling temperatures on five microalloyed steels with additions of Ti, Nb, Mo, Cr and V, to investigate the effects of microalloy additions and processing conditions on microstructures as well as mechanical properties. Subsized tensile specimens obtained from as-twisted torsion samples were used to evaluate mechanical properties. The precipitation states of the five steels with different processing conditions were characterized using extraction replica TEM. Comparison of microstructures and mechanical properties was discussed. Characterization of the microstructure via light optical microscopy showed the matrix microstructure was mainly influenced by coiling temperature, which indicates that the transformation from austenite to ferrite occurred during the coiling period. A higher Ti content was shown to reduce the second constituent fractions. Investigation of carbon extraction replica specimens via TEM revealed the presence of nanoscale precipitation. Extensive nanoscale precipitation was observed in most of the specimens having a polygonal ferrite matrix, while in the granular bainite/ferrite microstructure at lower temperatures, fewer microalloy carbides were present. The specimens with polygonal ferrite had similar or higher yield strength than the specimens with granular bainite microstructure, which suggests the effectiveness of precipitation strengthening from extensive nanoscale precipitates. In the Nb-Mo steel, more significant strengthening due to grain refinement was evident. Yield strength values were less than reported for JFE's "NANOHITEN®" steel in specimens with similar microstructure (polygonal ferrite matrix with extensive nanoscale precipitation).

Sun, Jun

224

Impact on multilayered composite plates  

NASA Technical Reports Server (NTRS)

Stress wave propagation in a multilayer composite plate due to impact was examined by means of the anisotropic elasticity theory. The plate was modelled as a number of identical anisotropic layers and the approximate plate theory of Mindlin was then applied to each layer to obtain a set of difference-differential equations of motion. Dispersion relations for harmonic waves and correction factors were found. The governing equations were reduced to difference equations via integral transforms. With given impact boundary conditions these equations were solved for an arbitrary number of layers in the plate and the transient propagation of waves was calculated by means of a Fast Fourier Transform algorithm. The multilayered plate problem was extended to examine the effect of damping layers present between two elastic layers. A reduction of the interlaminar normal stress was significant when the thickness of damping layer was increased but the effect was mostly due to the softness of the damping layer. Finally, the problem of a composite plate with a crack on the interlaminar boundary was formulated.

Kim, B. S.; Moon, F. C.

1977-01-01

225

Structural features and gas tightness of EB-PVD 1Ce10ScSZ electrolyte films  

NASA Astrophysics Data System (ADS)

The structure of Ceria doped Scandia Stabilized Zirconia (1Ce10ScSZ) electrolyte film deposited by EB-PVD (Electron Beam-Physical Vapour Deposition) technique on NiO-ZrO2 substrate was characterized by electron microscopy. The highly porous substrate was densely covered by deposited film without any spallation. The produced electrolyte layer was of a columnar structure with bushes, bundles of a diameter up to 30 ?m and diverse height. Between the columns, delamination cracks of few microns length were visible. The annealing of zirconia film at 1000 °C resulted in its densification. The columnar grains and delaminating cracks changed their shape into a bit rounded. High magnification studies revealed nanopores 5-60 nm formed along the boundaries of the columnar grains during annealing. High-quality contacts between the electrolyte film and anode substrate ensured good conductivity of the electrolyte film and high efficiency of SOFC.

Andrzejczuk, M.; Vasylyev, O.; Brychevskyi, M.; Dubykivskyi, L.; Smirnova, A.; Lewandowska, M.; Kurzyd?owski, K. J.; Steinberger-Wilckens, R.; Mertens, J.; Haanappel, V.

2012-09-01

226

Polyvinylidenefluoride (PVdF) based novel polymer electrolytes complexed with Mg(ClO{4}){2}  

NASA Astrophysics Data System (ADS)

The polyvinylidenefluoride (PVdF) based novel polymer electrolytes have been prepared by solution casting technique for solid state rechargeable magnesium batteries. Tetraglyme and tetrabutyl ammoniumchloride were used respectively as plasticizer and filler. The Mg(ClO{4})4 was used as conducting source. A.c. impedance spectroscopy results reveal that 5 wt% TBACl containing electrolyte show the maximum conductivity of 4.32 × 10-4 S/cm at ambient temperature. This electrolyte was electrochemically stable upto 1.5 V which was observed through linear sweep voltammetry. X-ray diffractograms studies suggest that the electrolytes are completely in amorphous phase. The improved entanglement like surface morphology was well observed for 5 wt% TBACl containing electrolyte by scanning electron microscope. The activation energy and coherence length were calculated.

Vickraman, P.; Aravindan, V.; Srinivasan, T.; Jayachandran, M.

2009-01-01

227

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

228

Tunable optical properties of multilayers black phosphorus  

E-print Network

We calculated the optical conductivity tensor of multilayers black phosphorus using the Kubo formula within an effective low-energy Hamiltonian. The optical absorption spectra of multilayers black phosphorus are shown to vary sensitively with thickness, doping, and light polarization. In conjunction with experimental spectra obtained from infrared absorption spectroscopy, we discuss the role of interband coupling and disorder on the observed anisotropic absorption spectra. Multilayers black phosphorus might offer attractive alternatives to narrow gap compound semiconductors for optoelectronics across mid- to near-infrared frequencies.

Low, Tony; Carvalho, A; Jiang, Yongjin; Wang, Han; Xia, Fengnian; Neto, A H Castro

2014-01-01

229

Fracture characterization of multilayered reservoirs  

SciTech Connect

Fracture treatment optimization techniques have been developed using Long-Spaced-Digital-Sonic (LSDS) log, pumpin-flowback, mini-frac, and downhole treating pressure data. These analysis techniques have been successfully applied in massive hydraulic fracturing (MHF) of ''tight gas'' wells. Massive hydraulic fracture stimulations have been used to make many tight gas reservoirs commercially attractive. However, studies have shown that short highly conductive fractures are optimum for the successful stimulation of wells in moderate permeability reservoirs. As a result, the ability to design and place optimal fractures in these reservoirs is critical. This paper illustrates the application of fracture analysis techniques to a moderate permeability multi-layered reservoir. These techniques were used to identify large zonal variations in rock properties and pore pressure which result from the complex geology. The inclusion of geologic factors in fracture treatment design allowed the placement of short highly conductive fractures which were used to improve injectivity and vertical sweep, and therefore, ultimate recovery.

Britt, L.K.; Larsen, M.J.

1986-01-01

230

Highly Efficient Multilayer Thermoelectric Devices  

NASA Technical Reports Server (NTRS)

Multilayer thermoelectric devices now at the prototype stage of development exhibit a combination of desirable characteristics, including high figures of merit and high performance/cost ratios. These devices are capable of producing temperature differences of the order of 50 K in operation at or near room temperature. A solvent-free batch process for mass production of these state-of-the-art thermoelectric devices has also been developed. Like prior thermoelectric devices, the present ones have commercial potential mainly by virtue of their utility as means of controlled cooling (and/or, in some cases, heating) of sensors, integrated circuits, and temperature-critical components of scientific instruments. The advantages of thermoelectric devices for such uses include no need for circulating working fluids through or within the devices, generation of little if any noise, and high reliability. The disadvantages of prior thermoelectric devices include high power consumption and relatively low coefficients of performance. The present development program was undertaken in the hope of reducing the magnitudes of the aforementioned disadvantages and, especially, obtaining higher figures of merit for operation at and near room temperature. Accomplishments of the program thus far include development of an algorithm to estimate the heat extracted by, and the maximum temperature drop produced by, a thermoelectric device; solution of the problem of exchange of heat between a thermoelectric cooler and a water-cooled copper block; retrofitting of a vacuum chamber for depositing materials by sputtering; design of masks; and fabrication of multilayer thermoelectric devices of two different designs, denoted I and II. For both the I and II designs, the thicknesses of layers are of the order of nanometers. In devices of design I, nonconsecutive semiconductor layers are electrically connected in series. Devices of design II contain superlattices comprising alternating electron-acceptor (p)-doped and electron-donor (n)-doped, nanometer- thick semiconductor layers.

Boufelfel, Ali

2006-01-01

231

Trapping atoms using nanoscale quantum vacuum forces.  

PubMed

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

232

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

233

Anomalous electrical conductivity of nanoscale colloidal suspensions.  

PubMed

The electrical conductivity of colloidal suspensions containing nanoscale conducting particles is nontrivially related to the particle volume fraction and the electrical double layer thickness. Classical electrochemical models, however, tend to grossly overpredict the pertinent effective electrical conductivity values, as compared to those obtained under experimental conditions. We attempt to address this discrepancy by appealing to the complex interconnection between the aggregation kinetics of the nanoscale particles and the electrodynamics within the double layer. In particular, we model the consequent alterations in the effective electrophoretic mobility values of the suspension by addressing the fundamentals of agglomeration-deagglomeration mechanisms through the pertinent variations in the effective particulate dimensions, solid fractions, as well as the equivalent suspension viscosity. The consequent alterations in the electrical conductivity values provide a substantially improved prediction of the corresponding experimental findings and explain the apparent anomalous behavior predicted by the classical theoretical postulates. PMID:19206448

Chakraborty, Suman; Padhy, Sourav

2008-10-28

234

TryEngineering: Exploring at the Nanoscale  

NSDL National Science Digital Library

This is a lesson plan that explores how nanotechnology has impacted the world. It was developed to help students visualize just how tiny a nanometer is and how scientists work to apply principles of nanotechnology. In hands-on activities, students evaluate and compare the surface areas at the macroscopic and nanoscale level. Links are provided to images of nanoscale objects produced by scanning electron microscopy (SEM). In the culminating activity, learners prepare a mock proposal for funding a nanotechnology application of their choosing. The lesson includes objectives and learner outcomes, problem sets, student guides, recommended reading, illustrated procedures, worksheets, and background information about the engineering connections. This collection is part of TryEngineering.org, a website maintained by the Institute of Electrical and Electronics Engineers (IEEE).

2013-01-02

235

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

236

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

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

Molecular dynamics simulation of nanoscale liquid flows  

Microsoft Academic Search

Molecular dynamics (MD) simulation is a powerful tool to investigate the nanoscale fluid flow. In this article, we review\\u000a the methods and the applications of MD simulation in liquid flows in nanochannels. For pressure-driven flows, we focus on\\u000a the fundamental research and the rationality of the model hypotheses. For electrokinetic-driven flows and the thermal-driven\\u000a flows, we concentrate on the principle

Yuxiu LiJinliang XuDongqing Li; Jinliang Xu; Dongqing Li

2010-01-01

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

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.

2009-10-06

241

Nanoscale Materials Modification for Device Applications  

Microsoft Academic Search

This chapter considers device applications of ion beams that involve nanoscale modification of materials. It is necessarily\\u000a selective and does not include broad classes of applications such as ion beam assisted deposition of thin films or tribological\\u000a modification of surfaces for improved wear, corrosion resistance or biocompatibility. Instead it aims to illustrate the diversity\\u000a of ion beam applications by providing

Robert G. Elliman

242

Nanoscale structure in crystalline solid solution alloys  

Microsoft Academic Search

The importance of local structure to the physical properties of alloys is receiving increasing attention. Recent measurements of the short-range nanoscale structure in metallic solid solution alloys reveal both the local chemical order and the chemically sensitive nearneighbor distances. These measurements are made possible by intense and tunable synchrotron X radiation; X-ray energy is adjusted to vary the x-ray scattering

X. Jiang

1996-01-01

243

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

244

Microwave sintering of multilayer ceramic capacitors.  

National Technical Information Service (NTIS)

Multilayer ceramic capacitors of several compositions (both Z5U and NPO types) were sintered in air in both conventional and microwave furnaces. Several casketing and insulation techniques were used to improve temperature uniformity and minimize dopant lo...

R. J. Lauf, C. E. Holcombe, C. Hamby

1992-01-01

245

Wetpaint: Scraping Through Multi-Layered Images  

E-print Network

We introduce a technique for exploring multi-layered images by scraping arbitrary areas to determine meaningful relationships. Our system, called Wetpaint, uses perceptual depth cues to help users intuitively navigate ...

Bonanni, Leonardo Amerigo

246

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

247

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

248

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

249

Scanning Coherent X-ray Diffraction Imaging of Pinned GdFe Magnetic Multilayers  

NASA Astrophysics Data System (ADS)

Crucial to understanding fundamental physics puzzles such as colossal magnetoresistance and developing future technologies for magnetic data storage is an understanding of the nanoscale behavior of magnetism. We study Gd/Fe multilayers exhibiting ordered stripes due to perpendicular magnetic anisotropy (PMA) that are pinned by artificial Au patterns. Using element sensitivity and depth resolution of Coherent X-ray Diffraction Imaging (CXDI), we investigate the magnetic domain structure, observing the role of disorder in the formation and stability of the magnetic domains. We recorded coherent diffraction data by scanning overlapping regions on the sample using linearly polarized light both on and off the Gd M5 resonant edge These diffraction patterns are then numerically inverted using ptychographic iterative algorithms to give a high resolution map of the Au structure and the ferromagnetic domain configuration as we scan through the magnetization hysteresis loop.

Dietze, Sebastian; Marsh, Moses; Tripathi, Ashish; Uhlir, Vojtech; Fullerton, Eric; Vine, David; McNulty, Ian; Shpyrko, Oleg

2012-02-01

250

Planar multilayer assemblies containing block copolymer aggregates.  

PubMed

The design, preparation, and properties of planar multilayer structures composed of various combinations of sequentially deposited polyelectrolyte (PE) chains and self-assembled layers of individual block copolymer aggregates (vesicles, micelles, or large compound micelles (LCMs)) are described. The aggregates contain negatively or positively charged corona chains while the PE multilayers contain alternating polyanionic or polycationic chains deposited on silicon wafers. The final structures consist of combinations of layers of various charged species: multilayers of alternating PEs of poly(allyl hydrochloride) (PAH) and poly(acrylic acid) (PAA) as well as vesicles, micelles, or large compound micelles of ionized poly(styrene)-b-poly(4-vinylpyridine) (PS-b-P4VP) or of poly(styrene)-b-poly(acrylic acid) (PS-b-PAA). Two types of layer-by-layer (LbL) multilayer structures were studied: individual aggregate layers sandwiched between PE multilayers and layers of individual aggregates of various morphologies and of different corona chain charges, deposited on top of each other without intermediate multilayers or individual layers of PEs. The strong interactions between the successive layers are achieved mainly by electrostatic attraction between the oppositely charged layers. The planar LbL multilayers containing block copolymer aggregates could, potentially, be used as carriers for multiple functional components; each aggregate layer could be loaded with hydrophobic (in the core of the micelles, LCMs, or vesicle walls) or hydrophilic functional molecules (in the vesicular cavities). The overall thickness of such planar LbL multilayers can be controlled precisely and can vary from tens of nanometers to several micrometers depending on the number of layers, the sizes of the aggregates, and the complexity of the structure. PMID:24417699

Xiao, Lin; Vyhnalkova, Renata; Sailer, Miloslav; Yang, Guang; Barrett, Christopher J; Eisenberg, Adi

2014-01-28

251

Multichannel bandpass filters utilizing multilayer photonic crystal.  

PubMed

We demonstrate multichannel optical bandpass filters utilizing alternating dielectric multilayers stacked on a patterned substrate. A microstructured Si/SiO(2) multilayer was formed by rf biased magnetron sputtering process on a fused silica substrate with surface gratings. The bandwidths of each filter channel were measured to be 50~175 nm in the near infrared region. Control of center wavelength and bandwidth by the grating pitch was verified. PMID:23595443

Ohtera, Yasuo; Yamada, Hirohito

2013-04-15

252

Effects of interlayer slip on multilayered folds  

E-print Network

of interlayer slip. The specimen is jacketed with three layers of thermo-shrink polyolefin tubing to isolate it from the confining fluid. Experimental Conditions All specimens are shortened parallel to the long axis of the multilayer specimen assemblage... of interlayer slip. The specimen is jacketed with three layers of thermo-shrink polyolefin tubing to isolate it from the confining fluid. Experimental Conditions All specimens are shortened parallel to the long axis of the multilayer specimen assemblage...

Casarta, Lawrence Joseph

2012-06-07

253

Multilayer Thin Film Sensors for Damage Diagnostics  

NASA Astrophysics Data System (ADS)

The new innovative approach to damage diagnostics within the production and maintenance/servicing procedures in industry is proposed. It is based on the real-time multiscale monitoring of the smart-designed multilayer thin film sensors of fatigue damage with the standard electrical input/output interfaces which can be connected to the embedded and on-board computers. The multilayer thin film sensors supply information about the actual unpredictable deformation damage, actual fatigue life, strain localization places, damage spreading, etc.

Protasov, A. G.; Gordienko, Y. G.; Zasimchuk, E. E.

2006-03-01

254

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

255

Occupational Medicine Implications of Engineered Nanoscale Particulate Matter  

E-print Network

Safety in Nanotechnology Research Occupational Medicinenanotechnology revolution promises dramatic advancements in science, technology, medicineMedicine Implications of Engineered Nanoscale Particulate Matter The emerging nanotechnology

Kelly, Richard J.

2008-01-01

256

Investigations on friction and wear mechanisms of the PVD-TiAlN coated carbide in dry sliding against steels and cast iron  

Microsoft Academic Search

The tribological behaviour of the monolayer PVD-titanium aluminium nitride (TiAlN) coated carbide inserts in unidirectional dry sliding against steel and cast iron counterparts was investigated using the pin-on-disc standard test with varying sliding speeds and normal loads. Three different materials of various machinability rates were used as the counterparts, namely the normalised medium carbon steel C45 equivalent to AISI 1045,

W. Grzesik; Z. Zalisz; S. Krol; P. Nieslony

2006-01-01

257

Charge–discharge studies on a lithium cell composed of PVdF-HFP polymer membranes prepared by phase inversion technique with a nanocomposite cathode  

Microsoft Academic Search

A novel polymer membrane of poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) co-polymer was prepared by the phase inversion technique with two different non-solvents, 1-butanol or hexane. The prepared films were analyzed by scanning electron microscope (SEM) and nitrogen absorption\\/desorption techniques. The change in the morphology and pore diameter of the films prepared with different non-solvents correlates with the structure of the non-solvents used.

A Manuel Stephan; Dale Teeters

2003-01-01

258

Design and performance of AlTiN and TiAlCrN PVD coatings for machining of hard to cut materials  

Microsoft Academic Search

Machining of hard to cut materials such as hardened steels and high temperature strong aerospace materials is a challenge of modern manufacturing. Two categories of the aluminum-rich TiAlN-based Physical Vapor Deposited (PVD) coatings, namely AlTiN and TiAlCrN, are commonly used for this area of application. A comparative investigation of the structural characteristics, various micro-mechanical properties, oxidation resistance and service properties

G. S. Fox-Rabinovich; A. I. Kovalev; M. H. Aguirre; B. D. Beake; K. Yamamoto; S. C. Veldhuis; J. L. Endrino; D. L. Wainstein; A. Y. Rashkovskiy

2009-01-01

259

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

260

Supplemental multilayer insulation research facility  

NASA Technical Reports Server (NTRS)

The Supplemental Multilayer Insulation Research Facility (SMIRF) provides a small scale test bed for conducting cryogenic experiments in a vacuum environment. The facility vacuum system is capable of simulating a Space Shuttle launch pressure profile as well as providing a steady space vacuum environment of 1.3 x 10(exp -4) Newton/sq meter (1 x 10(exp -6) torr). Warm side boundary temperatures can be maintained constant between 111 K (200 R) and 361 K (650 R) using a temperature controlled shroud. The shroud can also simulate a typical lunar day-night temperature profile. The test hardware consists of a cryogenic calorimeter supported by the lid of the vacuum chamber. A 0.45 cu meter (120 gallon) vacuum jacketed storage/supply tank is available for conditioning the cryogen prior to use in the calorimeter. The facility was initially designed to evaluate the thermal performance of insulation systems for long-term storage in space. The facility has recently been used to evaluate the performance of various new insulation systems for LH2 and LN2 ground storage dewars.

Dempsey, P. J.; Stochl, R. J.

1995-01-01

261

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

262

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

263

Probing nanoscale deformations of a fluctuating interface  

E-print Network

We consider the contribution of thermal capillary waves to the interaction between a fluid-fluid interface and a nearby nanoparticle. Fluctuations are described thanks to an effective interaction potential which is derived using the renormalization group. The general theory is then applied to a spherical particle interacting with the interface through van der Waals forces. Surprisingly enough, we find that fluctuations contribute significantly to the deformation profile. Our study therefore reveals that thermal fluctuations cannot be ignored when probing nanoscale deformations of a soft interface.

Thomas Bickel

2014-04-01

264

Current-Induced Effects in Nanoscale Conductors  

Microsoft Academic Search

We present an overview of current-induced effects in nanoscale conductors with emphasis on their description at the atomic\\u000a level. In particular, we discuss steady-state current fluctuations, current-induced forces, inelastic scattering and local\\u000a heating. All of these properties are calculated in terms of single-particle wavefunctions computed using a scattering approach\\u000a within the static density-functional theory of many-electron systems. Examples of current-induced

Neil Bushong; Massimiliano Di Ventra

2005-01-01

265

Synthesis, dynamics and photophysics of nanoscale systems  

NASA Astrophysics Data System (ADS)

The emerging field of nanotechnology, which spans diverse areas such as nanoelectronics, medicine, chemical and pharmaceutical industries, biotechnology and computation, focuses on the development of devices whose improved performance is based on the utilization of self-assembled nanoscale components exhibiting unique properties owing to their miniaturized dimensions. The first phase in the conception of such multifunctional devices based on integrated technologies requires the study of basic principles behind the functional mechanism of nanoscale components, which could originate from individual nanoobjects or result as a collective behaviour of miniaturized unit structures. The comprehensive studies presented in this thesis encompass the mechanical, dynamical and photophysical aspects of three nanoscale systems. A newly developed europium sulfide nanocrystalline material is introduced. Advances in synthetic methods allowed for shape control of surface-functionalized EuS nanocrystals and the fabrication of multifunctional EuS-CdSe hybrid particles, whose unique structural and optical properties hold promise as useful attributes of integrated materials in developing technologies. A comprehensive study based on a new class of multifunctional nanomaterials, derived from the basic unit of barcoded metal nanorods is presented. Their chemical composition affords them the ability to undergo autonomous motion in the presence of a suitable fuel. The nature of their chemically powered self-propulsion locomotion was investigated, and plausible mechanisms for various motility modes were presented. Furthermore functionalization of striped metallic nanorods has been realized through the incorporation of chemically controlled flexible hinges displaying bendable properties. The structural aspect of the light harvesting machinery of a photosynthetic cryptophyte alga, Rhodomonas CS24, and the mobility of the antenna protein, PE545, in vivo were investigated. Information obtained through a combination of steady-state and time-resolved spectroscopy in conjunction with quantum chemical calculations aided in the elucidation of the dynamics and the mechanism of light harvesting in the multichromophoric phycobiliprotein phycocyanin PC645 in vitro. Investigation of the light-harvesting efficiency and optimization of energy transfer with respect to the structural organization of light-harvesting chromophores on the nanoscale, can provide us with fundamental information necessary for the development of synthetic light-harvesting devices capable of mimicking the efficiency of the natural system.

Mirkovic, Tihana

266

Visualizing viral assemblies in a nanoscale biosphere.  

PubMed

We present a novel microfluidic platform to examine biological assemblies at high-resolution. We have engineered a functionalized chamber that serves as a "nanoscale biosphere" to capture and maintain rotavirus double-layered particles (DLPs) in a liquid environment. The chamber can be inserted into the column of a transmission electron microscope while being completely isolated from the vacuum system. This configuration allowed us to determine the structure of biological complexes at nanometer-resolution within a self-contained vessel. Images of DLPs were used to calculate the first 3D view of macromolecules in solution. We refer to this new fluidic visualization technology as in situ molecular microscopy. PMID:23208001

Gilmore, Brian L; Showalter, Shannon P; Dukes, Madeline J; Tanner, Justin R; Demmert, Andrew C; McDonald, Sarah M; Kelly, Deborah F

2013-01-21

267

Quantum Thermoelectric Effects on the Nanoscale  

NASA Astrophysics Data System (ADS)

An exact expression for the heat current in a nanostructure coupled to multiple metallic electrodes is derived, including both electron-electron and electron-phonon interactions. We use this formalism to investigate quantum effects on the flow of charge and entropy, and find an enormous quantum enhancement of thermoelectric effects in the vicinity of higher-order interferences in the transmission spectrum of a nanoscale junction. A nonequilibrium quantum analysis of a single-molecule junction based on 3,3'-biphenyldithiol demonstrates a maximum operating efficiency of 27% of the Carnot limit. Nonlocal quantum corrections to thermoelectric transport coefficients in multiterminal geometries are predicted.

Bergfield, Justin; Stafford, Charles

2011-03-01

268

Nanoscale atomic waveguides with suspended carbon nanotubes  

E-print Network

We propose an experimentally viable setup for the realization of one-dimensional ultracold atom gases in a nanoscale magnetic waveguide formed by single doubly-clamped suspended carbon nanotubes. We show that all common decoherence and atom loss mechanisms are small guaranteeing a stable operation of the trap. Since the extremely large current densities in carbon nanotubes are spatially homogeneous, our proposed architecture allows to overcome the problem of fragmentation of the atom cloud. Adding a second nanowire allows to create a double-well potential with a moderate tunneling barrier which is desired for tunneling and interference experiments with the advantage of tunneling distances being in the nanometer regime.

V. Peano; M. Thorwart; A. Kasper; R. Egger

2005-05-27

269

Tuning magnetic anisotropy in Fe/Pt multilayers on Pt(001) by surface charging  

NASA Astrophysics Data System (ADS)

Magnetic anisotropy of nanoscale systems has recently received considerable attention from both experimentally and theoretically perspectives. Diverse ways of manipulating the anisotropy have been sought and found. Those include alloying, external electric field exposure and electrolyte charging. However, the hunt for a system that would exhibit a large anisotropy and be easy to manipulate at the same time is still on. By using density functional theory tools, we study the magnetic anisotropy of Fe/Pt multilayers on Pt(001). Our fully relativistic ab initio calculations demostrate that the value of magnetic anisotropy energy (MAE) strongly depends on the composition of Fe/Pt multilayers, achieving remarkable large values for systems featuring Fe layers capped with Pt. For instance, positive charging of a Fe slab capped with Pt enhances significantly the MAE. More intriguing is the behavior of Fe bilayers, for which surface charging does not only change the value of the anisotropy but can also lead in the switching of the easy axis. To understand the physics underlying this behavior of MAE, we analyze the electronic structure of the system by means of the second-order perturbation theory linking MAE to the local density of electronic states near the Fermi level.

Ruiz-Diaz, Pedro; Stepanyuk, Valeri

2013-03-01

270

Scanning Coherent X-ray Diffraction Imaging of GdFe Magnetic Multilayers  

NASA Astrophysics Data System (ADS)

Crucial to understanding fundamental physics puzzles such as colossal magnetoresistance and developing future technologies for magnetic data storage is an understanding of the nanoscale behavior of magnetism. Probes with the ability to see beyond surfaces on this length scale, ultimately on ultrafast time scales, would greatly enhance this understanding. Coherent X-ray Diffraction Imaging (CXDI) is a promising new technique with wavelength-limited resolution that can probe deeply beyond surfaces. We studied the evolution of ``worm'' domains in a ferrimagnetic GdFe multilayer film as a function of applied field using CXDI. Ferromagnetic domains in the multilayer produce high contrast speckle when the film is illuminated with linearly polarized coherent x-rays resonant at the Gd M5 edge. This diffraction is purely magnetic since the sample is electronically amorphous. We recorded coherent diffraction data by scanning overlapping regions on the sample. These diverse diffraction patterns are then numerically inverted using ptychographic iterative algorithms to give a high resolution map of the ferromagnetic domain configuration.

Tripathi, A.; Kim, S. S.; Mohanty, J.; Dietze, S.; Shipton, E.; Chan, K.; Fullerton, E.; Shpyrko, O.; McNulty, I.

2010-03-01

271

Systematic modification of the rheological properties of colloidal suspensions with polyelectrolyte multilayers  

NASA Astrophysics Data System (ADS)

Tailoring rheological properties of colloidal suspensions with the adsorption of polyelectrolyte multilayers (PEMs) is based on the idea of controlling macroscopic mechanical properties by modifying the particle surface in a reproducible and well-understood manner. With layer-by-layer self-assembly, monodisperse polystyrene particles are coated with up to ten layers of the oppositely charged strong polyelectrolytes: poly(diallyl dimethyl ammonium chloride) and poly(styrene sulfonate). The conformation of the adsorbed polyelectrolyte is controlled by the ionic strength of the used aqueous polyelectrolyte solution. For 1M NaCl solution, a brushlike adsorption of the polyelectrolyte is expected. The ability of PEMs to serve on a nanoscale level as surface modifiers and influence macroscopic rheological properties like viscoelasticity, yield stress, and shear banding is discussed. The mechanical behavior of these suspensions is qualitatively described by the theory of Derjaguin-Landau-Verwey-Overbeek with short-range repulsion and long-range attraction. A scaling rule is proposed which distinguishes between the precusor and the multilayer regime.

Hess, Andreas; Pretzl, Melanie; Heymann, Lutz; Fery, Andreas; Aksel, Nuri

2011-09-01

272

Strategies for tuning phonon transport in multilayered structures using a mismatch-based particle model  

NASA Astrophysics Data System (ADS)

The performance of many micro- and nanoscale devices depends on the ability to control interfacial thermal transport, which is predominantly mediated by phonons in semiconductor systems. The phonon transmissivity at an interface is therefore a quantity of interest. In this work, an empirical model, termed the thermal mismatch model, is developed to predict transmissivity at ideal interfaces between semiconductor materials, producing an excellent agreement with molecular dynamics simulations of wave packets. To investigate propagation through multilayered structures, this thermal mismatch model is then incorporated into a simulation scheme that represents wave packets as particles, showing a good agreement with a similar scheme that used molecular dynamics simulations as input [P. K. Schelling and S. R. Phillpot, J. Appl. Phys. 93, 5377 (2003)]. With these techniques validated for both single interfaces and superlattices, they are further used to identify ways to tune the transmissivity of multilayered structures. It is shown that by introducing intermediate layers of certain atomic masses, the total transmissivity can either be systematically enhanced or reduced compared to that of a single interface. Thus, this model can serve as a computationally inexpensive means of developing strategies to control phonon transmissivity in applications that may benefit from either enhancement (e.g., microelectronics) or reduction (e.g., thermoelectrics) in thermal transport.

Le, Nam Q.; Duda, John C.; English, Timothy S.; Hopkins, Patrick E.; Beechem, Thomas E.; Norris, Pamela M.

2012-04-01

273

Absence of a ferromagnetic phase in pure Ge quantum dots and Ge/SiO2 multilayer films  

NASA Astrophysics Data System (ADS)

Quantum magnetism is currently one of the most challenging areas of materials science. Research efforts have been concentrated on studying the onset of the nano-scale systems that are originally non-magnetic in bulk forms. Recently, claims of the existence of Ge-based ferromagnetism in pure Ge quantum dots and Ge/SiO2 multilayer films have attracted certain attention from the scientific world. However, if both Ge quantum dots and Ge/SiO2 multilayer films were able to form ordered magnetic states without the contribution of extrinsic inclusions, the induced ferromagnetism would be certainly incompatible with our knowledge of magnetism in physics. We therefore reinitiate an investigation in order to examine the validity of their claims. Unfortunately, our results have shown that neither pure Ge quantum dots nor Ge/SiO2 multilayer films were able to exhibit ferromagnetism. The ferromagnetism of the “ferromagnetic Ge” was most likely originated from contaminants, such as Fe and Ni and not from Ge.

Chi, Y. C.; Chao, J. H.

2014-08-01

274

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

275

Tg and Cure of a Polycyanurate at the Nanoscale  

Microsoft Academic Search

Nanoscale constraint is known to have a significant impact on the thermal properties of materials. Although thermosetting resins have been cured in the presence of nanoparticles and nanotubes, cure of thermosetting resins under the well defined nanoscale constraints imposed by controlled pore glass (CPG) or similar matrices has not been previously documented. In this work, we investigate the isothermal curing

Sindee Simon; Qingxiu Li

2008-01-01

276

A Nanoscale Mechanism of Fatigue in Ionic Solids  

E-print Network

A Nanoscale Mechanism of Fatigue in Ionic Solids Emily A. A. Jarvis National Institute of Standards ABSTRACT We employ periodic density functional theory to explore the effect of cyclic tensile loading on the behavior of alumina in the threshold region of crack formation. We find evidence for nanoscale fatigue when

Carter, Emily A.

277

Method to determine thermal profiles of nanoscale circuitry  

DOEpatents

A platform that can measure the thermal profiles of devices with nanoscale resolution has been developed. The system measures the local temperature by using an array of nanoscale thermometers. This process can be observed in real time using a high resolution imagining technique such as electron microscopy. The platform can operate at extremely high temperatures.

Zettl, Alexander K; Begtrup, Gavi E

2013-04-30

278

Magnetic superlattices and their nanoscale phase transition effects  

E-print Network

- dimensionally (3D) ordered binary magnetic superlattices con- structed through the coassembly of Fe3O4 and CoMagnetic superlattices and their nanoscale phase transition effects Jinwoo Cheon* , Jong-Il Park) The systematic assembly of nanoscale constituents into highly ordered superlattices is of significant interest

Kim, Sehun

279

Comment on `Nanoscale water capillary bridges under deeply negative  

E-print Network

Comment on `Nanoscale water capillary bridges under deeply negative pressure' [Chem. Phys. Lett bridge formed in humid air. They claimed that their 'research shows that nanoscale water capillary bridges are metastable and have absolutely negative pressure approaching the limit of stability for water

Balibar, Sébastien

280

Plastic behavior of Cu/Ni multilayers  

SciTech Connect

In order to study the plasticity in Cu-Ni multilayers deposited on single crystals of nanoindentation measurements, and by the transmission of well characterized dislocations from the underlying substrate by tensile deformation of Cu single crystals. Various multilayers were deposited by physical vapor deposition with layer thicknesses varying between 1,000 and 20 Angstroms (for a total thickness between 0.8 and 1 {micro}m). Two types of experiments were designed. The first one aimed at injecting, in a controlled way, some dislocations from the substrate into the multilayers; the second type of experiment concerned the structure of the multilayer surface after having plastically pushed the material away from a nanoindenter. This communication reports the results from the nanoindentation measurements, as well as the observations of slip on the surface. The authors observed through the injection of dislocations by nanoindentation that the multilayers increase in strength with refinement of the layer structure but at thicknesses below 35 {angstrom} exhibits a softening behavior. Also observation of the upheaval around the nanoindent showed an evolution from slip lines to more spread plasticity with refinement of the layer structure.

Verdier, M.; Hawley, M.; Nastasi, M.; Kung, H. [Los Alamos National Lab., NM (United States); Niewczas, M. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering; Embury, J.D. [Los Alamos National Lab., NM (United States)]|[McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

1998-12-31

281

Multilayer thin film thermoelectrics produced by sputtering  

SciTech Connect

In this work we explore the possibility of achieving bulk electrical properties in single layer sputter deposited films grown epitaxially on (111) oriented BaF{sub 2} substrates. There are a number of sputter deposition parameters that can be varied in order to optimize the film quality. It is important to understand the effect of varying the deposition temperature, Ar sputtering gas pressure, and the substrate bias. We will consider only Bi and Bi{sub 0.86}Sb{sub 0.14} films in this paper. These materials were chosen since they have the same simple structure, two different band gaps and do not change significantly either in physical or electrical properties with small amounts of cross contamination. We will also present our work on multilayer thermoelectrics made of Bi and Bi{sub 0.86}Sb{sub 0.14} layers. There has been considerable interest in this multilayer structure in the literature. Theoretical calculations of the band structure and interface states of these multilayer structures have been made by Mustafaev and Agassi et al. respectively [6,7]. Experimentally Yoshida et al. have examined similar multilayer structures grown by MBE as well as Bi/Sb multilayer samples in which report an anomalous thermoelectric power [8].

Wagner, A.V.; Foreman, R.J.; Summers, L.J.; Barbee, T.W. Jr.; Farmer, J.C.

1995-06-19

282

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

283

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

284

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

285

Nanoscale phenomena in synthetic functional oxide heterostructures.  

PubMed

This paper reviews nanoscale phenomena such as polarization relaxation dynamics and piezoelectric characterization in model ferroelectric thin films and nanostructures using voltage-modulated scanning force microscopy. Using this technique we show the three-dimensional reconstruction of the polarization vector in lead zirconate titanate (PZT) thin films. Second, the time-dependent relaxation of remanent polarization in epitaxial PZT ferroelectric thin films, containing a uniform two-dimensional grid of 90 degrees domains (c-axis in the plane of the film), has been investigated extensively. The 90 degrees domain walls preferentially nucleate the 180 degrees reverse domains during relaxation. Relaxation occurs through the nucleation and growth of reverse 180 degrees domains, which subsequently coalesce and consume the entire region as a function of relaxation time. In addition we also present results on investigation of the relaxation phenomenon on a very local scale, where pinning and bowing of domain walls has been observed. We also show how this technique is used for obtaining quantitative information on piezoelectric constants and by engineering special structures, and how we realize ultrahigh values of piezoconstants. Last, we also show direct hysteresis measurements on nanoscale capacitors, where there is no observable loss of polarization in capacitors as small as 0.16 microm2 in area. PMID:12533230

Nagarajan, V; Ganpule, C S; Stanishevsky, A; Liu, B T; Ramesh, R

2002-08-01

286

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

287

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

288

High Spectral Resolution With Multilayer Gratings  

SciTech Connect

The improvement of spectral resolution brought about by the use of multilayer grating (MG) instead of multilayer mirror (MM) is analyzed. The spectrum of a complex sample containing various elements excited under electron irradiation is studied. This sample is a pellet made by pressing powders of Cu and compounds with Fe and F atoms. The MM is a Mo/B{sub 4}C periodic multilayer with a period of about 6 nm; for the MG a grating of 1 {mu}m period has been etched in the MM. It is shown that the MG can easily resolve the F Kalpha and Fe Lalpha emissions, separated by about 30 eV, whereas the MM is unable to give such a performance. A comparison with an EDS (SDD) detector is also given. It is also shown that the MG can improve the detection limit. Finally the role of the slit placed in front of the detector is discussed.

Andre, J.-M.; Le Guen, K.; Jonnard, P. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France)

2010-04-06

289

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

290

Optimized capping layers for EUV multilayers  

DOEpatents

A new capping multilayer structure for EUV-reflective Mo/Si multilayers consists of two layers: A top layer that protects the multilayer structure from the environment and a bottom layer that acts as a diffusion barrier between the top layer and the structure beneath. One embodiment combines a first layer of Ru with a second layer of B.sub.4 C. Another embodiment combines a first layer of Ru with a second layer of Mo. These embodiments have the additional advantage that the reflectivity is also enhanced. Ru has the best oxidation resistance of all materials investigated so far. B.sub.4 C is an excellent barrier against silicide formation while the silicide layer formed at the Si boundary is well controlled.

Bajt, Sasa (Livermore, CA); Folta, James A. (Livermore, CA); Spiller, Eberhard A. (Livermore, CA)

2004-08-24

291

Multilayer filter design with high K materials  

NASA Astrophysics Data System (ADS)

A novel approach to filter design is presented. A high-K multilayer coupled line filter is designed for optimal performance within a dielectric resonator of rectangular cross section. The multilayer filter is shown to have a performance comparable to its planar counterpart as well as the Lange coupler while maintaining the design advantages that come with the multilayer approach to filter design such as increased flexibility in managing parameter constraints. The performance of the rectangular cross sectioned resonator in terms of modal response and resonant frequency has been evaluated through mathematical derivation and simulation. The reader will find the step by step process to designing the resonant structure as well as a MATLAB script that will graphically display the effect changing various parameters may have on resonator size to assist in the design analysis. The resonator has been designed to provide a finite package in terms of space and performance so that it may house the multilayer filter on a printed circuit board for ease of system implementation. The proposed design with analysis will prove useful for all multilayer coupled line filter types that may take advantage of the uniform environment provided by the finite packaging of the dielectric resonator. As with any microwave system, considerable effort must be put forth to maintain signal integrity throughout the delivery process from the signal input to reception at the output. As a result a large amount of effort and research has gone into answering the question of how to efficiently feed both a dielectric resonator filter of rectangular cross section as well as a coupled line filter that would be embedded within the resonators confines. Several methods for feeding have been explored and reported on. Of the feeding methods reported on the most feasible design includes a unique microstrip delivery to the embedded multilayer filter as pictured here.* *Please refer to dissertation for diagram.

Curtis, Nathaniel, II

292

Yield stress and scaling of polyelectrolyte multilayer modified suspensions: effect of polyelectrolyte conformation during multilayer assembly.  

PubMed

The yield stress of polyelectrolyte multilayer modified suspensions exhibits a surprising dependence on the polyelectrolyte conformation of multilayer films. The rheological data scale onto a universal master curve for each polyelectrolyte conformation as the particle volume fraction, ?, and the ionic strength of the background fluid, I, are varied. It is shown that rough films with highly coiled, brushy polyelectrolytes significantly enhance the yield stress. Moreover, via the ionic strength I of the background fluid, the dynamic yield stress of brushy polyelectrolyte multilayers can be finely adjusted over 2 decades. PMID:23952570

Hess, Andreas; Aksel, Nuri

2013-09-10

293

The Fabrication and Bandgap Engineering of Photonic Multilayers**  

E-print Network

to fabricate multilayer colloidal crystals formed by the layer-by-layer deposition of silica beads on a glass crystallization,[8,27±30] gravity sedimentation,[24,31] elec- tro-hydrodynamic deposition,[32,33] colloidal, a multilayer crystal, using successive deposition of crystals of colloids of arbitrary sizes. The multilayer

Mittleman, Daniel

294

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

295

Piezoelectric multilayer actuator life test.  

PubMed

Potential NASA optical missions such as the Space Interferometer Mission require actuators for precision positioning to accuracies of the order of nanometers. Commercially available multilayer piezoelectric stack actuators are being considered for driving these precision mirror positioning mechanisms. These mechanisms have potential mission operational requirements that exceed 5 years for one mission life. To test the feasibility of using these commercial actuators for these applications and to determine their reliability and the redundancy requirements, a life test study was undertaken. The nominal actuator requirements for the most critical actuators on the Space Interferometry Mission (SIM) in terms of number of cycles was estimated from the Modulation Optics Mechanism (MOM) and Pathlength control Optics Mechanism (POM) and these requirements were used to define the study. At a nominal drive frequency of 250 Hz, one mission life is calculated to be 40 billion cycles. In this study, a set of commercial PZT stacks configured in a potential flight actuator configuration (pre-stressed to 18 MPa and bonded in flexures) were tested for up to 100 billion cycles. Each test flexure allowed for two sets of primary and redundant stacks to be mechanically connected in series. The tests were controlled using an automated software control and data acquisition system that set up the test parameters and monitored the waveform of the stack electrical current and voltage. The samples were driven between 0 and 20 V at 2000 Hz to accelerate the life test and mimic the voltage amplitude that is expected to be applied to the stacks during operation. During the life test, 10 primary stacks were driven and 10 redundant stacks, mechanically in series with the driven stacks, were open-circuited. The stroke determined from a strain gauge, the temperature and humidity in the chamber, and the temperature of each individual stack were recorded. Other properties of the stacks, including the displacement from a capacitance gap sensor and impedance spectra were measured at specific intervals. The average degradation in the stroke over the life test was found to be small (<3%) for the primary stacks and <4% for the redundant stacks. It was noted that about half of the stroke reduction occurred within the first 10 billion cycles. At the end of the life test, it was found that the actuator could recover about half of the lost stroke by applying a dc voltage of 100 V at room temperature. The data up to 100 billion cycles for these tests and the analysis of the experimental results are presented in this paper. PMID:21507759

Sherrit, Stewart; Bao, Xiaoqi; Jones, Christopher M; Aldrich, Jack B; Blodget, Chad J; Moore, James D; Carson, John W; Goullioud, Renaud

2011-04-01

296

Fine tuning of activity for nanoscale catalysts.  

SciTech Connect

Ability to tune the electronic and structural properties of nanocatalysts can potentially lead towards the superior catalytic enhancement that was reported for the Pt{sub 3}Ni(111)-skin surface. Here we report investigation of the extended well-defined surfaces of Pt and PtM alloys (M=Ni,Co,Fe,V,Ti,Re) as well as Pt(hkl) single crystalline surfaces for various catalytic reaction. The electrode surfaces were initially characterized in ultra-high vacuum by AES, LEIS and UPS before controlled transfer into electrochemical environment. Catalytic properties have been determined in three compartment electrochemical cell for oxygen reduction reaction (ORR) by rotational disk electrode technique. The single crystalline surfaces of Pt electrodes have been used to benchmark the activity range that could be expected on pure Pt electrodes. We have proposed that surface modifications induced by the second metal, and consequent catalytic enhancements could occur through the following effects: (1) Electronic effect, due to changes in the metallic d-band center position vs. Fermi level; and (2) Structural effect, which reflects relationship between atomic geometry, and/or surface chemistry, i.e., dissolution - surface roughening. It has been reported that Pt bimetallic alloys, could form surfaces with two different compositions. Due to surface segregation annealed surfaces can form the outermost Pt-skin surface layer, while the lightly sputtered surfaces have the bulk ratio of alloying components and form Pt-skeleton outermost layers as a result of dissolution of non-precious atoms. In principle, different near-surface compositions (Pt-skin, Pt-skeleton and polycrystalline Pt) have been found to have different electronic structures. Modification in Pt electronic properties alters adsorption/catalytic properties of corresponding materials. The most active systems for the electrochemical oxygen reduction reaction (ORR) are established to be the Pt-skin near-surface formation. The similar levels of catalytic enhancement have been established for corresponding nanoscale materials. In addition to electronic properties we have found how catalytic activity could be affected by the arrangement of surface defects on nanoscale surfaces. Ability to control surface and near surface catalyst properties enables fine tuning of catalytic activity and stability of nanoscale surfaces.

Strmcnik, D.; van derVliet, D.; Lucas, C.; Karapetrov, G.; Markovic, N.; Stamenkovic, V.; Materials Science Division

2008-01-01

297

PREFACE: Superconductivity in ultrathin films and nanoscale systems Superconductivity in ultrathin films and nanoscale systems  

NASA Astrophysics Data System (ADS)

The recent technological developments in the synthesis and characterization of high-quality nanostructures and developments in the theoretical techniques needed to model these materials, have motivated this focus section of Superconductor Science and Technology. Another motivation is the compelling evidence that all new superconducting materials, such as iron pnictides and chalcogenides, diborides (doped MgB2) and fullerides (alkali-doped C60 compounds), are heterostrucures at the atomic limit, such as the cuprates made of stacks of nanoscale superconducting layers intercalated by different atomic layers with nanoscale periodicity. Recently a great amount of interest has been shown in the role of lattice nano-architecture in controlling the fine details of Fermi surface topology. The experimental and theoretical study of superconductivity in the nanoscale started in the early 1960s, shortly after the discovery of the BCS theory. Thereafter there has been rapid progress both in experiments and the theoretical understanding of nanoscale superconductors. Experimentally, thin films, granular films, nanowires, nanotubes and single nanoparticles have all been explored. New quantum effects appear in the nanoscale related to multi-component condensates. Advances in the understanding of shape resonances or Fano resonances close to 2.5 Lifshitz transitions near a band edge in nanowires, 2D films and superlattices [1, 2] of these nanosized modules, provide the possibility of manipulating new quantum electronic states. Parity effects and shell effects in single, isolated nanoparticles have been reported by several groups. Theoretically, newer techniques based on solving Richardson's equation (an exact theory incorporating finite size effects to the BCS theory) numerically by path integral methods or solving the entire Bogoliubov-de Gennes equation in these limits have been attempted, which has improved our understanding of the mechanism of superconductivity in these confined systems. In addition, the role of thermodynamic fluctuations on superconducting properties has been extensively studied in the context of nanoparticles and nanowires both experimentally and theoretically. In the past decade, a lot of work has been initiated in the area of interface superconductivity where different techniques have been demonstrated to tune Tc. Although the progress in this field has deepened our understanding of nanoscale superconductors, there are several open and key questions which need to be addressed. Some of these are: (1) can superconductivity be enhanced and Tc increased in nanostructures with respect to the bulk limit and if so, how can it be controlled? (2) What are the theoretical and experimental limits for the enhancement and control of superconductivity? (3) Can the phenomena identified in conventional nanostructures shed light on phenomena in high Tc superconductors and vice versa? (4) How will the new fundamental physics of superconductivity at the nanoscale promote advances in nanotechnology applications and vice versa? The papers in this focus section reflect the advances made in this field, in particular in nanowires and nanofilms, but also attempt to answer some of the key open questions outlined above. The theoretical papers explore unconventional quantum phenomena such as the role of confinement in the dynamics of single Cooper pairs in isolated grains [1] and Fano resonances in superconducting gaps in multi-condensate superconductors near a 2.5 Lifshitz transition [2]. Here a new emerging class of quantum phenomena of fundamental physics appear at the Bose-BCS crossover in multi-condensate superconductors [2]. Nanosize effects can now be manipulated by controlling defects in layered oxides [3]. A new approach is provided by controlling the self-organization of oxygen interstitials in layered copper oxides that show an intrinsic nanoscale phase separation [4]. In this case a non-trivial distribution of superconducting nanograins appears to enhance the critical temperature [4]. This is a hot topic as in the past year many wo

Bianconi, Antonio; Bose, Sangita; Garcia-Garcia, Antonio Miguel

2012-12-01

298

Nanoscale Conducting Oxide PlasMOStor.  

PubMed

We experimentally demonstrate an ultracompact PlasMOStor, a plasmon slot waveguide field-effect modulator based on a transparent conducting oxide active region. By electrically modulating the conducting oxide material deposited into the gaps of highly confined plasmonic slot waveguides, we demonstrate field-effect dynamics giving rise to modulation with high dynamic range (2.71 dB/?m) and low waveguide loss (?0.45 dB/?m). The large modulation strength is due to the large change in complex dielectric function when the signal wavelength approaches the surface plasmon resonance in the voltage-tuned conducting oxide accumulation layer. The results provide insight about the design of ultracompact, nanoscale modulators for future integrated nanophotonic circuits. PMID:25302668

Lee, Ho W; Papadakis, Georgia; Burgos, Stanley P; Chander, Krishnan; Kriesch, Arian; Pala, Ragip; Peschel, Ulf; Atwater, Harry A

2014-11-12

299

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

300

Minority carrier effects in nanoscale Schottky contacts.  

PubMed

We report the current-voltage behavior for nanoscale point contacts to Si(111) obtained in ultrahigh vacuum using scanning tunneling microscopy. Epitaxial CoSi(2) islands provide single-crystal contacts with well-defined size and shape. The zero bias conductance is found to be independent of the island size (10(2)-10(4) nm(2)) and shape, but varies strongly with the surface Fermi level position. This behavior is explained by the recombination-generation current from minority carriers at the free surface, which may be orders of magnitude larger than the majority carrier thermionic or tunnel currents across the contact interface. This can give rise to large shifts of the apparent ideality factor and Schottky barrier height for the point contact. PMID:19671959

Hao, Lifeng; Bennett, P A

2009-09-01

301

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

302

Interface effect on ferroelectricity at the nanoscale.  

PubMed

Interfaces play a critical role in nanoscale ferroelectricity. We perform a first-principles study of ultrathin KNbO(3) ferroelectric films placed between two metal electrodes, either SrRuO(3) or Pt. We show that bonding at the ferroelectric-metal interfaces imposes severe constraints on the displacement of atoms, destroying the bulk tetragonal soft mode. If the interface bonding is sufficiently strong, the ground-state represents a ferroelectric domain with an interface domain wall, driven by the intrinsic oppositely oriented dipole moments at the two interfaces. The critical thickness for the net polarization of the KNbO(3) film is predicted to be about 1 nm for Pt and 1.8 nm for SrRuO(3) electrodes. PMID:16522047

Duan, Chun-Gang; Sabirianov, Renat F; Mei, Wai-Ning; Jaswal, Sitaram S; Tsymbal, Evgeny Y

2006-03-01

303

Implementation of perception and action at nanoscale  

E-print Network

Real time combination of nanosensors and nanoactuators with virtual reality environment and multisensorial interfaces enable us to efficiently act and perceive at nanoscale. Advanced manipulation of nanoobjects and new strategies for scientific education are the key motivations. We have no existing intuitive representation of the nanoworld ruled by laws foreign to our experience. A central challenge is then the construction of nanoworld simulacrum that we can start to visit and to explore. In this nanoworld simulacrum, object identifications will be based on probed entity physical and chemical intrinsic properties, on their interactions with sensors and on the final choices made in building a multisensorial interface so that these objects become coherent elements of the human sphere of action and perception. Here we describe a 1D virtual nanomanipulator, part of the Cit\\'e des Sciences EXPO NANO in Paris, that is the first realization based on this program.

Marlière, Sylvain; Marchi, Florence; Luciani, Annie; Chevrier, Joel

2008-01-01

304

Nondestructive Inspection Of Foam And Multilayer Insulations  

NASA Technical Reports Server (NTRS)

Techniques and equipment enable nondestructive inspection of sprayed-on foam and multilayer reflecting thermal insulations on metallic substrates. Technology is applied in factories and laboratories; to inspect insulation on cryogenic tanks and pipes. Equipment includes probe head, several electronic modules that take measurements via electromagnetic and electrostatic sensors in probe head, small computer to store and process signals from modules, and printer.

Krause, Dennis R.; Bauman, Robert J.; Davis, Thomas J.

1989-01-01

305

Semi-analytical solutions for multilayer reservoirs  

E-print Network

Intercept Case 3 aj + bj tD Linear p[wDj(tD)] Case 4 a[j] exp(bj tD) Exponential p[wDj(tD)] Case 5 General formulation: p[wsD(tD)] = [] Total Pressure/Rate Averaging} Our work illustrates the validity of each approximate multilayer solution...

Lolon, Elyezer Pabibak

2012-06-07

306

Multilayer Film Assembly of Carbon Nanotubes  

NASA Technical Reports Server (NTRS)

An approach to assemble multilayers of carbon nanotubes on a substrate is presented. Chemical vapor deposition using a transition metal catalyst formulation is used to grow the nanotubes. Results show a bilayer assembly of nanotubes each with a different density of tubes.

Cassell, Alan M.; Meyyappan, M.; Han, Jie; Arnold, J. (Technical Monitor)

2000-01-01

307

Performing Feature Selection With Multilayer Perceptrons  

Microsoft Academic Search

An experimental study on two decision issues for wrapper feature selection (FS) with multilayer perceptrons and the sequential backward selection (SBS) procedure is presented. The decision issues studied are the stopping criterion and the network retraining before computing the saliency. Experimental results indicate that the increase in the computational cost associated with retraining the network with every feature temporarily removed

Enrique Romero; Josep María Sopena

2008-01-01

308

Delamination of multilayer thermal barrier coatings  

Microsoft Academic Search

Multilayer thermal barrier coatings (TBCs) on superalloy substrates are comprised of an intermetallic bond coat, a thermally grown oxide (TGO) layer, and a porous zirconia top coat that provides thermal protection. The TGO attains a thickness of 1–10 ?m prior to failure, while the bond coat and zirconia layer are each about 50–100 ?m thick. The preferred method for manufacturing

Sung Ryul Choi; John W. Hutchinson; A. G. Evans

1999-01-01

309

Periodic multilayer gratings of arbitrary shape  

NASA Astrophysics Data System (ADS)

We obtain the optical response of a multilayered system in which the interfaces have a common periodicity but arbitrary shape by extending a published method previously restricted to interfaces with identical profiles [J. Opt. Soc. Am. 72, 839 (1982)]. Numerical comparisons with other modeling results for grating systems are presented that show the effectiveness of the new method.

Preist, T. W.; Cotter, N. P. K.; Sambles, J. R.

1995-08-01

310

Robust Visual Recognition Using Multilayer Generative Neural  

E-print Network

. . . . . . . . . . . . . . . . . . . . . . . 4 2.1.1 Convolutional Neural Networks (CNNs) . . . . . . . . . . . . . . . 5 2.1.2 The StandardRobust Visual Recognition Using Multilayer Generative Neural Networks by Yichuan Tang A thesis to the public. ii #12;Abstract Deep generative neural networks such as the Deep Belief Network and Deep

Anderson, Charles H.

311

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

312

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

313

Nondestructive characterization of nanoscale layered samples.  

PubMed

Multilayered samples consisting of Al, Co and Ni nanolayers were produced by MBE and characterized nondestructively by means of SRXRF, mu-XRF, WDXRF, RBS, XRR, and destructively with SIMS. The main aims were to identify the elements, to determine their purity and their sequence, and also to examine the roughness, density, homogeneity and thickness of each layer. Most of these important properties could be determined by XRF methods, e.g., on commercial devices. For the thickness, it was found that all of the results obtained via XRR, RBS, SIMS and various XRF methods (SRXRF, mu-XRF, WDXRF) agreed with each other within the limits of uncertainty, and a constant deviation from the presets used in the MBE production method was observed. Some serious preliminary discrepancies in the results from the XRF methods were examined, but all deviations could be explained by introducing various corrections into the evaluation methods and/or redetermining some fundamental parameters. PMID:18998118

Baake, Olaf; Hoffmann, Peter S; Flege, Stefan; Ortner, Hugo M; Gottschalk, Sebastian; Berky, Wolfram; Balogh, Adam G; Ensinger, Wolfgang; Beckhoff, Burkhard; Kolbe, Michael; Gerlach, Martin; Pollakowski, Beatrix; Weser, Jan; Ulm, Gerhard; Haschke, Michael; Blokhina, Elena; Peter, Markus; Porta, Dominique; Heck, Martin

2009-01-01

314

Flexible free-standing TiO2/graphene/PVdF films as anode materials for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Graphene composites were prepared by hydrothermal method using titanium dioxide (TiO2) adsorbed graphene oxide (GO) sheets as precursors. Free-standing hybrid films for lithium-ion batteries were prepared by adding TiO2/graphene composites to the polyvinylidene fluoride (PVdF)/N-methyl-2-pyrrolidone (NMP) solution, followed by a solvent evaporation technique. These films were characterized by atomic force microscopy (AFM), X-ray diffraction (XRD), scanning electron microscopy (SEM) and various electrochemical techniques. Flexible films show an excellent cycling performance, which was attributed to the interconnected graphene conducting network, which depressed the increasing of electric resistance during the cycling.

Ren, H. M.; Ding, Y. H.; Chang, F. H.; He, X.; Feng, J. Q.; Wang, C. F.; Jiang, Y.; Zhang, P.

2012-12-01

315

Layer-dependent nanoscale electrical properties of graphene studied by conductive scanning probe microscopy  

PubMed Central

The nanoscale electrical properties of single-layer graphene (SLG), bilayer graphene (BLG) and multilayer graphene (MLG) are studied by scanning capacitance microscopy (SCM) and electrostatic force microscopy (EFM). The quantum capacitance of graphene deduced from SCM results is found to increase with the layer number (n) at the sample bias of 0 V but decreases with n at -3 V. Furthermore, the quantum capacitance increases very rapidly with the gate voltage for SLG, but this increase is much slowed down when n becomes greater. On the other hand, the magnitude of the EFM phase shift with respect to the SiO2 substrate increases with n at the sample bias of +2 V but decreases with n at -2 V. The difference in both quantum capacitance and EFM phase shift is significant between SLG and BLG but becomes much weaker between MLGs with a different n. The layer-dependent quantum capacitance behaviors of graphene could be attributed to their layer-dependent electronic structure as well as the layer-varied dependence on gate voltage, while the layer-dependent EFM phase shift is caused by not only the layer-dependent surface potential but also the layer-dependent capacitance derivation. PMID:21851595

2011-01-01

316

Extraordinary sensitivity of nanoscale infrared spectroscopy demonstrated on Graphene and thin SiO2  

NASA Astrophysics Data System (ADS)

Infrared Spectroscopy is a powerful tool for characterizing materials by their vibrational mode fingerprint and/or electron conductivity. Its application to nanoscale resolved studies is highly desirable but remained challenging mainly for two reasons: a suitable source of intense, broadband infrared illumination was not widely available and the spatial resolution of conventional microscopes was limited by diffraction. We have resolved both issues by utilizing tunable External Cavity Quantum Cascade Lasers (EC-QCLs) as an intense illumination source for a scattering Scanning Near Field Optical Microscope (s-SNOM), capable of <10nm spatial resolution. With this combination of EC-QCLs + s-SNOM we demonstrate <10nm resolution imaging and spectroscopy of extremely thin materials: Silicon oxide layers (SiO2) as thin as 2nm and even single atomic layers of Carbon (Graphene). The spectra register contrasts for volumes as small as 20x20x1nm^3 = 400 yoktoliters of SiO2, and about 70 yl of Graphene over a broad spectral range: 1065-2250cm-1. We explain the origins of this extraordinary sensitivity with an improved theoretical framework for calculating the near field response of a multilayer system.

Andreev, Greg; Fei, Z.; Bao, W.; Zhao, Z.; Lau, C. N.; Zhang, L. M.; Fogler, M.; Dominguez, G.; Thiemens, M.; Keilmann, F.; Basov, D.

2011-03-01

317

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

318

Molecular Dynamics Simulations of Heat Transfer In Nanoscale Liquid Films  

E-print Network

Molecular Dynamics (MD) simulations of nano-scale flows typically utilize fixed lattice crystal interactions between the fluid and stationary wall molecules. This approach cannot properly model thermal interactions at the wall-fluid interface...

Kim, Bo Hung

2010-07-14

319

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

320

Characterisation of electromagnetic compatibility drifts of nanoscale integrated  

E-print Network

Characterisation of electromagnetic compatibility drifts of nanoscale integrated circuit after interferences. For the first time an electromagnetic compatibility (EMC) qualification procedure is proposed to increasing usage of high speed and complex electronic systems, electromagnetic compatibility (EMC) is a major

Paris-Sud XI, Université de

321

Nano-scale scratching in chemical-mechanical polishing  

E-print Network

During the chemical-mechanical polishing (CMP) process, a critical step in the manufacture of ultra-large-scale integrated (ULSI) semiconductor devices, undesirable nano-scale scratches are formed on the surfaces being ...

Eusner, Thor

2008-01-01

322

Electronic structure and transport in molecular and nanoscale electronics  

E-print Network

Two approaches based on first-principles method are developed to qualitatively and quantitatively study electronic structure and phase-coherent transport in molecular and nanoscale electronics, where both quantum mechanical ...

Qian, Xiaofeng

2008-01-01

323

BIOPHYSICS LETTER Transport at the nanoscale: temperature dependence  

E-print Network

BIOPHYSICS LETTER Transport at the nanoscale: temperature dependence of ion conductance Catalin European Biophysical Societies' Association 2008 Abstract Temperature dependent ion conductance details of the ion transport. Comparing the temperature dependence of the channel conductance

Movileanu, Liviu

324

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.

325

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

326

Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray.  

National Technical Information Service (NTIS)

Nanoscale materials (nanomaterials) have been described as having at least one dimension on the order of approximately 1100 nanometers (nm) (NSTC, 2011). Although this size range is not universally accepted and continues to evolve, 100 nm is typically use...

2012-01-01

327

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.

328

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

329

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.

330

Perspectives Nanotechnology and the public: Effectively communicating nanoscale science  

E-print Network

Perspectives Nanotechnology and the public: Effectively communicating nanoscale science August 2006 Key words: nanotechnology, communication, public knowledge, public understanding the public on concepts and applications associated with nanotechnology. The goal of our work

Crone, Wendy C.

331

An Open and Shut Case at the Nanoscale  

NSF Publications Database

... many potential applications are nanoscale drug delivery systems that could release pharmaceuticals ... NSF news electronically through the e-mail delivery and notification system, MyNSF (formerly the ...

332

A new method to produce nanoscale iron for nitrate removal  

Microsoft Academic Search

This article proposes a novel technology combining electrochemical and ultrasonic methods to produce nanoscale zero valent iron (NZVI). With platinum placed in the cathode and the presence of the dispersion agent, 0.2g\\/l cetylpyridinium chloride (CPC), a cation surfactant, in the solution, the nanoscale iron particle was successfully produced with diameter of 1–20 nm and specific surface area of 25.4m2\\/g. The

Shiao-Shing Chen; Hong-Der Hsu; Chi-Wang Li

2004-01-01

333

A numerical study of ballistic transport in a nanoscale MOSFET  

Microsoft Academic Search

We examine the physics of ballistic transport in a nanoscale MOSFET as reflected in the shape of the distribution function. We calculate the electron distribution function in the ballistic limit by solving the 1D steady-state Boltzmann transport equation self-consistently with the 2D Poisson equation in an n-channel ultra-thin-body nanoscale double-gate SOI MOSFET. In equilibrium, symmetry of the distribution function is

Jung-Hoon Rhew; Zhibin Ren; Mark S. Lundstrom

2002-01-01

334

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

335

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

336

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.

337

Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings  

SciTech Connect

The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and processing techniques for these coatings. In addition, we investigated the effect of microstructure on the mechanical properties and oxidation protection ability of the coatings. Coatings were developed to provide oxidation protection to both ferritic and austentic alloys and Ni-based alloys. The coatings that we developed are based on low viscosity pre-ceramic polymers. Thus they can be easily applied to any shape by using a variety of techniques including dip-coating, spray-coating and painting. The polymers are loaded with a variety of nanoparticles. The nanoparticles have two primary roles: control of the final composition and phases (and hence the properties); and control of the shrinkage during thermal decomposition of the polymer. Thus the selection of the nanoparticles was the most critical aspect of this project. Based on the results of the processing studies, the performance of selected coatings in oxidizing conditions (both static and cyclic) was investigated.

Rajendra Bordia

2009-07-31

338

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

339

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

340

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

341

Deconvolution of mixed magnetism in multilayer graphene  

NASA Astrophysics Data System (ADS)

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; Bahadur, Dhirendra

2014-06-01

342

The structure and dynamics of multilayer networks  

NASA Astrophysics Data System (ADS)

In the past years, network theory has successfully characterized the interaction among the constituents of a variety of complex systems, ranging from biological to technological, and social systems. However, up until recently, attention was almost exclusively given to networks in which all components were treated on equivalent footing, while neglecting all the extra information about the temporal- or context-related properties of the interactions under study. Only in the last years, taking advantage of the enhanced resolution in real data sets, network scientists have directed their interest to the multiplex character of real-world systems, and explicitly considered the time-varying and multilayer nature of networks. We offer here a comprehensive review on both structural and dynamical organization of graphs made of diverse relationships (layers) between its constituents, and cover several relevant issues, from a full redefinition of the basic structural measures, to understanding how the multilayer nature of the network affects processes and dynamics.

Boccaletti, S.; Bianconi, G.; Criado, R.; del Genio, C. I.; Gómez-Gardeñes, J.; Romance, M.; Sendiña-Nadal, I.; Wang, Z.; Zanin, M.

2014-11-01

343

The structure and dynamics of multilayer networks  

E-print Network

In the past years, network theory has successfully characterized the interaction among the constituents of a variety of complex systems, ranging from biological to technological, and social systems. However, up until recently, attention was almost exclusively given to networks in which all components were treated on equivalent footing, while neglecting all the extra information about the temporal- or context-related properties of the interactions under study. Only in the last years, taking advantage of the enhanced resolution in real data sets, network scientists have directed their interest to the multiplex character of real-world systems, and explicitly considered the time-varying and multilayer nature of networks. We offer here a comprehensive review on both structural and dynamical organization of graphs made of diverse relationships (layers) between its constituents, and cover several relevant issues, from a full redefinition of the basic structural measures, to understanding how the multilayer nature of...

Boccaletti, S; Criado, R; del Genio, C I; Gómez-Gardeñes, J; Romance, M; Sendiña-Nadal, I; Wang, Z; Zanin, M

2014-01-01

344

Computerized multilevel analysis for multilayered fiber composites  

NASA Technical Reports Server (NTRS)

A FORTRAN 4 computer code for the micromechanics, macromechanics, and laminate analysis of multilayered fiber composite structural components is described. The code can be used either individually or as a subroutine within a complex structural analysis/synthesis program. The inputs to the code are constituent materials properties, composite geometry, and loading conditions. The outputs are various properties for ply and composite; composite structural response, including bending-stretching coupling; and composite stress analysis, including comparisons with failure criteria for combined stress. The code was used successfully in the analysis and structural synthesis of flat panels, in the buckling analysis of flat panels, in multilayered composite material failure studies, and lamination residual stresses analysis.

Chamis, C. C.

1972-01-01

345

Lead-free multilayer piezoelectric transformer.  

PubMed

In this article, a multilayer piezoelectric transformer based on lead-free Mn-doped 0.94(Bi(12)Na(12))TiO(3)-0.06BaTiO(3) 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 degrees C, the transformer has an output power of >0.3 W. With a matching load resistance of 10 Omega, its maximum efficiency approaches 81.5%, and the maximum voltage gain is 0.14. It has potential to be used in low voltage power supply units such as low power adapter and other electronic circuits. PMID:17503954

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

2007-01-01

346

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

347

Textures of Ta/Al multilayer films  

NASA Astrophysics Data System (ADS)

Ta/Al multilayer films with a modulation wavelength of 7.0 nm were grown using magnetron sputtering. The Bragg ?-2? scan pattern and the plate film photograph of x-ray diffraction reveal that the sample has Ta(110) and A1(111) axial textures with a mosaic spread of about ±5° and coherency strains. The structure change of the multilayer sample after annealing at 550 °C for 2 h is determined by the plate film photography of x-ray diffraction to study the thermal stability. It is found that after annealing a large amount of Ta and Al atoms at the interfaces are combined into TaAl3 with [(202)+(002)] textures.

Yuan, X. Y.; Wu, Z. Q.; Hu, A.; Jiang, S. S.; Qiu, Y.; Khatanova, N. A.; Ilyushin, R. S.

1993-04-01

348

Lateral mobility of polyelectrolyte chains in multilayers.  

PubMed

In this work, the lateral mobility of polyelectrolyte multilayers was investigated by means of the fluorescence recovery after photobleaching (FRAP) technique, with special attention to the effect of relevant parameters during and after preparation. Different polyelectrolytes with respect to charge density, stiffness, and hydrophilicity were compared. From the experimental results emerged that the density of charged sites along the polymer is the most important parameter controlling the formation of polymer complexes. At higher charge density, more complexes are formed, and the diffusion coefficient decreases. It was observed that the intrinsic backbone stiffness reduces the interpenetration of polyelectrolyte layers and the formation of complexes promoting the lateral mobility. In addition, the lateral mobility increases with increasing ionic strength and with decreasing hydration shell of the added anion in the polyelectrolyte solution. The effect of heating or annealing in electrolyte solution after preparation was also investigated along with the embedding of the probing layer at controlled distances to the multilayer surface. PMID:17461569

Nazaran, P; Bosio, V; Jaeger, W; Anghel, D F; Klitzing, R V

2007-07-26

349

Nanoscale magnetic biotransport with application to magnetofection.  

PubMed

We present a model for predicting the transport of biofunctional magnetic nanoparticles in a passive magnetophoretic system that consists of a fluidic chamber positioned above a rare-earth magnet. The model is based on a drift-diffusion equation that governs the particle concentration in the chamber. We solve this equation numerically using the finite volume method. We apply the model to the magnetofection process wherein the magnetic force produced by the magnet attracts magnetic carrier particles with surface-bound gene vectors toward the bottom of the chamber for transfection with target cells. We study particle transport and accumulation as a function of key variables. Our analysis indicates that the particles are magnetically focused toward the center of the chamber during transport, and that the rate of accumulation at the base can be enhanced using larger particles and/or by reducing the spacing between the magnet and the chamber. The model provides insight into the physics of particle transport at the nanoscale and enables rapid parametric analysis of particle accumulation, which is useful for optimizing novel magnetofection systems. PMID:18643307

Furlani, E P; Ng, K C

2008-06-01

350

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

351

Nanoscale platinum printing on insulating substrates  

NASA Astrophysics Data System (ADS)

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).

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

2013-12-01

352

Neurons sense nanoscale roughness with nanometer sensitivity.  

PubMed

The interaction between cells and nanostructured materials is attracting increasing interest, because of the possibility to open up novel concepts for the design of smart nanobiomaterials with active biological functionalities. In this frame we investigated the response of human neuroblastoma cell line (SH-SY5Y) to gold surfaces with different levels of nanoroughness. To achieve a precise control of the nanoroughness with nanometer resolution, we exploited a wet chemistry approach based on spontaneous galvanic displacement reaction. We demonstrated that neurons sense and actively respond to the surface nanotopography, with a surprising sensitivity to variations of few nanometers. We showed that focal adhesion complexes, which allow cellular sensing, are strongly affected by nanostructured surfaces, leading to a marked decrease in cell adhesion. Moreover, cells adherent on nanorough surfaces exhibit loss of neuron polarity, Golgi apparatus fragmentation, nuclear condensation, and actin cytoskeleton that is not functionally organized. Apoptosis/necrosis assays established that nanoscale features induce cell death by necrosis, with a trend directly related to roughness values. Finally, by seeding SH-SY5Y cells onto micropatterned flat and nanorough gold surfaces, we demonstrated the possibility to realize substrates with cytophilic or cytophobic behavior, simply by fine-tuning their surface topography at nanometer scale. Specific and functional adhesion of cells occurred only onto flat gold stripes, with a clear self-alignment of neurons, delivering a simple and elegant approach for the design and development of biomaterials with precise nanostructure-triggered biological responses. PMID:20308580

Brunetti, V; Maiorano, G; Rizzello, L; Sorce, B; Sabella, S; Cingolani, R; Pompa, P P

2010-04-01

353

Peptide assembly for nanoscale control of materials  

NASA Astrophysics Data System (ADS)

Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic, charged synthetic molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic interactions; in addition to more traditional self-assembling molecular attributes such as amphiphilicty, to define hierarchical material structure and consequent properties. Design strategies for materials self-assembly based on small (less than 24 amino acids) beta-hairpin peptides will be discussed. Self-assembly of the peptides is predicated on an intramolecular folding event caused by desired solution properties. Importantly, kinetics of self-assembly can be tuned in order to control gelation time. The final gel behaves as a shear thinning, but immediately rehealing, solid that is potentially useful for cell injection therapies. The morphological, and viscoelastic properties of these peptide hydrogels will be discussed. In addition, slight changes in peptide primary sequence can have drastic effects on the self-assembled morphology. Additional sequences will be discussed that do not form hydrogels but rather form nanoscale templates for inorganic material assembly.

Pochan, Darrin

2011-03-01

354

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

355

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

356

New Dark Matter Detector using Nanoscale Explosives  

E-print Network

We present nanoscale explosives as a novel type of dark matter detector and study the ignition properties. When a Weakly Interacting Massive Particle WIMP from the Galactic Halo elastically scatters off of a nucleus in the detector, the small amount of energy deposited can trigger an explosion. For specificity, this paper focuses on a type of two-component explosive known as a nanothermite, consisting of a metal and an oxide in close proximity. When the two components interact they undergo a rapid exothermic reaction --- an explosion. As a specific example, we consider metal nanoparticles of 5 nm radius embedded in an oxide. One cell contains more than a few million nanoparticles, and a large number of cells adds up to a total of 1 kg detector mass. A WIMP interacts with a metal nucleus of the nanoparticles, depositing enough energy to initiate a reaction at the interface between the two layers. When one nanoparticle explodes it initiates a chain reaction throughout the cell. A number of possible thermite mat...

Lopez, Alejandro; Freese, Katherine; Kurdak, Cagliyan; Tarle, Gregory

2014-01-01

357

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

358

Energy-harvesting at the Nanoscale  

NASA Astrophysics Data System (ADS)

Energy harvesting is the process by which energy is taken from the environment and transformed to provide power for electronics. Specifically, the conversion of thermal energy into electrical power, or thermoelectrics, can play a crucial role in future developments of alternative sources of energy. Unfortunately, present thermoelectrics have low efficiency. Therefore, an important task in condensed matter physics is to find new ways to harvest ambient thermal energy, particularly at the smallest length scales where electronics operate. To achieve this goal, there is on one hand the miniaturizing of electrical devices, and on the other, the maximization of either efficiency or power the devices produce. We will present the theory of nano heat engines able to efficiently convert heat into electrical power. We propose a resonant tunneling quantum dot engine that can be operated either in the Carnot efficient mode, or maximal power mode. The ability to scale the power by putting many such engines in a ``Swiss cheese sandwich'' geometry gives a paradigmatic system for harvesting thermal energy at the nanoscale.

Jordan, Andrew; Sothmann, Björn; Sánchez, Rafael; Büttiker, Markus

2013-03-01

359

Scattering by a multilayer chiral cylinder  

Microsoft Academic Search

An efficient recursive eigenfunction solution for the problem of scattering by a multilayer chiral circular cylinder, with or without a surface impedance center cylinder, is presented. For an M layer cylinder, the solution requires the multiplication of M4×4 matrices, versus the solution of a 4M×4M matrix equation in a standard approach. The problem of a transverse electric (TE) incident plane

Michael S. Kluskens; Edward H. Newman

1991-01-01

360

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

361

Multi-layered liposomes as optical resonators  

NASA Astrophysics Data System (ADS)

Multi-layered liposomes, comprising a concentric series of lipid bilayers - separated at fixed distances and compartmentalizing aqueous solutions of alternating refractive indices - are proposed as optical Bragg resonators. Seminal work focuses on the feasibility of successive encapsulations coupled with size-control via extrusion. Synthesis criteria for realization of these liposomes were subsequently discussed based on experimental observations. Numerical studies of the proposed structure showed discernible band gaps, qualifying their potential application in biological lasing.

Yong, Derrick; Ng, Wei Long; Lee, Elizabeth; Yu, Xia; Bosman, Michel; Chan, Chi Chiu

362

Hetero-twin formation during growth of nano-scale Al-TiN composites - experimental and DFT studies  

SciTech Connect

It is well known that high stacking fault energy metals such as Al do not form either growth twins or mechanical twins easily. Although mechanical twins in nanocrystalline Al have been observed under certain conditions, growth twins have never been observed. In this work, the authors report for the first time, through transmission electron microscopy (TEM), that Al layers, when deposited on TiN layers, tend to grow in a twin relationship to both the TiN layer and the underlying Al layer. The TiN layers assume the orientation of the Al layers below. Calculations using density functional theory (DFT) show that nitrogen termination in the {l_brace}111{r_brace} growth plane of the TiN layers favors the growth of twin oriented Al layers over these TiN layers. This finding provides a way to create a twin-modulated structure in Al with the inclusion of intermediate nm-scale layer of an ionic solid such as TiN. Al metal is resistant to twinning, as it has a high stacking fault energy (SFE) of > 150 mJ/m. Although twins have been observed in nano-scale grains of Al, and predicted by molecular dynamics (MD) simulations in conditions when the nanoscale grains are plastically deformed, no process or phenomenon has been reported yet in which the deposition of an intermediate layer of a different material phase causes the subsequent layer of Al to be deposited in the twin orientation. The authors show in this paper that it is possible to form Al layers in twin orientation to each other across polar TiN layers, if these are grown so that both the Al and TiN layers have a {l_brace}111{r_brace} surface as their growth front. Since the deposition of Al and TiN layers is used in the formation of diffusion barriers, and the mechanical properties of these nanoscale multilayers are also seen to be exceptional, it is important to investigate and understand their structure at the nanometer length scale, and thence to be able to control it. Moreover, these findings point out a method of introducing nano-scale twins in high SFE materials in general, and can potentially improve the properties of nano-layered materials.

Bhattacharyya, Dhriti [Los Alamos National Laboratory; Liu, Xiang - Yang [Los Alamos National Laboratory; Hoagland, Richard G [Los Alamos National Laboratory; Misra, Amit [Los Alamos National Laboratory; Genc, A [MSE, OSU; Fraser, H L [MSE, OSU

2009-01-01

363

Resonant Raman spectroscopy of twisted multilayer graphene.  

PubMed

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. PMID:25382099

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

2014-01-01

364

Stabilization of layer-by-layer engineered multilayered hollow microspheres.  

PubMed

Polymer multilayered hollow microspheres prepared by layer-by-layer (LbL) self-assembly attract more and more interest due to their unique application, especially as drug delivery system (DDS). Unfortunately, the multilayered hollow microspheres assembled via weak linkages could fuse and/or aggregate in high ionic strength media or strong acidic or basic media. This severely restricts the practical applications of the multilayered hollow microspheres as DDS in human physiological medium. In the present work, the progress in stabilization of the multilayered hollow microspheres is reviewed, with emphasis on the assembling process and their crosslinking mechanism. PMID:24321861

Liu, Peng

2014-05-01

365

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

366

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

367

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

368

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

369

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

370

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

371

Synthesis of ZrO2 nanoparticles in microwave hydrolysis of Zr (IV) salt solutions—Ionic conductivity of PVdF-co-HFP-based polymer electrolyte by the inclusion of ZrO2 nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocrystalline ZrO2 particles have been prepared by microwave hydrolysis of Zr(IV) salt solutions at 400C for 6 h. The paper describes the PVdF-co-HFP-ZrO2-based NCPEMs prepared by a simple solvent casting technique. The incorporation of ZrO2 nanoparticles in the PVdF-co-HFP matrix, improved the ionic conductivity due to the availability of a large amount of oxygen vacancies on ZrO2 surface which may act as the active Lewis acidic site that interact with ClO4- ions. On the other hand, a high concentration of ZrO2 [10 wt(%)] leads to depression in ionic conductivity due to the formation of more crystalline phase in the PVdF-co-HFP matrix. DSC, XRD, SEM and DC-polarization studies were carried out. This paper also explores and proposes a structure conductivity correlation in the PVdF-co-HFP-LiClO4 ZrO2-based NCPEMs system. The proposed correlation is derived from the interpretation of DSC, XRD and AC-impedance measurements. The temperature dependence of the ionic conductivity of NCPEMs follows the Arrhenius behaviour. Finally, the LSV experiment has been carried out to investigate the electrochemical stability in the polymer electrolytes.

Kalyana Sundaram, N. T.; Vasudevan, T.; Subramania, A.

2007-02-01

372

Nanoscale material design for photovoltaic applications  

NASA Astrophysics Data System (ADS)

Solar cell technology directly converts the clean, abundant energy of the sun into electricity. To build solar cell modules with low cost and high energy conversion efficiency, nanomaterials such as nanowires, nanotubes and quantum dots are very promising candidates, due to their novel thermal, electrical, and optical properties. This research seeks to use silicon nanowire, carbon nanotube, and semiconductor quantum dot to achieve high optical absorption and low electron-phonon coupling. Multiscale simulation and experiments are combined to investigate the thermal radiative properties of nanowire/nanotube array structures and the electron-phonon interaction in semiconductor quantum dots. Optical properties of nanowire/nanotube structures are numerically investigated by combined ab initio calculation and computational electromagnetic calculations. At the atomic scale, ab initio calculations based on density functional theory are performed to evaluate the spectral dielectric function of the material using the initial atomic structure as the only input parameter. This method considers different absorption mechanisms from far infrared to visible spectrum, and its effectiveness is demonstrated using the material GaAs and small carbon nanotubes. At the nanoscale, the predicted dielectric function of nanowire/nanotube is used as an input parameter in finite-difference time-domain method, so that the optical properties of devices such as nanowire/nanotube arrays can be obtained. Based on this scheme, we have shown that the vertically aligned multiwalled carbon nanotube arrays are nearly perfect absorber in the visible spectrum. Silicon nanowire arrays are less absorptive than carbon nanotube, but we propose and demonstrate that their optical absorption can be greatly enhanced by introducing structural randomness, including random positioning, diameter and length. The enhanced optical absorption implies potential enhancement of the overall efficiency of nanotube/nanowire array solar cells. Phonon-assisted electron decay in semiconductor quantum dots is also investigated in this work. In semiconductor solar cell, a large portion of energy loss is by the fast hot electron cooling, in which a high energy electron decays to the electronic band gap by creating a series of phonons. The excessive electrical energy is then converted to heat and wasted, so that the total photovoltaic energy conversion efficiency is limited. The electron decay rate reduces in semiconductor quantum dots, due to the discrete electron energy levels created by quantum confinement. To design quantum dots with the slowest decay rate, we use the non-adiabatic molecular dynamics to perform real-time simulations of the phonon-assisted electron decay process. This method is based on time-dependent density functional theory, and can directly predict the phonon-assisted electron decay time using the initial quantum dot structure as the only input. The numerical simulation shows that the phonon-induced electron decay can be slowed down in a small PbSe quantum dot. The temperature-dependent relaxation in this quantum dot is also studied, which helps us to propose a multi-channel relaxation mechanism. This mechanism provides new insights to the understanding of electron decay process in quantum dots. The results from this study have potentially important applications in solar energy harvesting and radiative thermal management. It offers a new perspective of nanoscale engineering of materials to achieve more efficient photovoltaic energy conversion.

Bao, Hua

373

Nanoscale Metal Oxide Semiconductors for Gas Sensing  

NASA Technical Reports Server (NTRS)

A report describes the fabrication and testing of nanoscale metal oxide semiconductors (MOSs) for gas and chemical sensing. This document examines the relationship between processing approaches and resulting sensor behavior. This is a core question related to a range of applications of nanotechnology and a number of different synthesis methods are discussed: thermal evaporation- condensation (TEC), controlled oxidation, and electrospinning. Advantages and limitations of each technique are listed, providing a processing overview to developers of nanotechnology- based systems. The results of a significant amount of testing and comparison are also described. A comparison is made between SnO2, ZnO, and TiO2 single-crystal nanowires and SnO2 polycrystalline nanofibers for gas sensing. The TECsynthesized single-crystal nanowires offer uniform crystal surfaces, resistance to sintering, and their synthesis may be done apart from the substrate. The TECproduced nanowire response is very low, even at the operating temperature of 200 C. In contrast, the electrospun polycrystalline nanofiber response is high, suggesting that junction potentials are superior to a continuous surface depletion layer as a transduction mechanism for chemisorption. Using a catalyst deposited upon the surface in the form of nanoparticles yields dramatic gains in sensitivity for both nanostructured, one-dimensional forms. For the nanowire materials, the response magnitude and response rate uniformly increase with increasing operating temperature. Such changes are interpreted in terms of accelerated surface diffusional processes, yielding greater access to chemisorbed oxygen species and faster dissociative chemisorption, respectively. Regardless of operating temperature, sensitivity of the nanofibers is a factor of 10 to 100 greater than that of nanowires with the same catalyst for the same test condition. In summary, nanostructure appears critical to governing the reactivity, as measured by electrical resistance of these SnO2 nanomaterials towards reducing gases. With regard to the sensitivity of the different nascent nanostructures, the electrospun nanofibers appear preferable

Hunter, Gary W.; Evans, Laura; Xu, Jennifer C.; VanderWal, Randy L.; Berger, Gordon M.; Kulis, Michael J.

2011-01-01

374

Nanoscale Building Blocks and Nanoassembly of Structures  

NASA Astrophysics Data System (ADS)

Electronics and photonics industries are highly interested in developing new methods for nanofabrication in order to be able to continue their long-term trend of building ever smaller, faster and less expensive devices. Conventional patterning strategies must be augmented by new techniques in order to truly take advantage of the quantum nature of novel nanoscale devices. In our research, we are developing a bottom-up approach to fabricate building blocks, which can be used to assemble nanostructures and devices. This involves the assembly of atom- and molecule-like nanostructures into functional 2-D and 3-D units. This will take advantage of the unique optical, electronic, and size-tunable properties of nanostructures and permit the use of these properties for "real" applications in a larger system (> 10 nm and < 1 um). Here, we demonstrate a novel technique for the fabrication of nano-assemblies of carbon nanotubes (CNT) and quantum dots (QD) (CNT-QD conjugates) for the first time using a zero length cross-linker. CNT's are primarily functionalized with carboxylic end groups by oxidation in concentrated sulfuric acid. Thiol stabilized QD's in aqueous solution with amino end groups were prepared in the laboratory. The ethylene carbodiimide coupling reaction was used to achieve the CNT-QD conjugation. Sulfo-N-Hydroxysuccinimide (sulfo-NHS) was used to enhance this coupling procedure. We present EDS and FTIR data for the chemical modification and SEM images of the first nano-building blocks. Current work includes the more complex 3-D assembly of QD's and nanotubes on Anodized Aluminum Oxide (AAO) template for nanodevices. Potential future applications of our method include the fabrication of novel electronic and photonic devices, crystal displays and biosensors.

Ozkan, Cengiz

2003-03-01

375

Magnetic mirrors at the nanoscale: theory  

NASA Astrophysics Data System (ADS)

The control of charged particles at sub micrometer and nanometer length scales presents an intrinsically interesting challenge, as well as being a rich field for the study of trapped ions and plasmas. Motivated by this, we obtain the exact solution for the vector potential for a wire of finite length and of arbitrary form. Closed form solutions can then be deduced describing the electromagnetic waves propagating from the wire. This allows us to investigate design parameters, so that we may produce spiral wire shapes which, when injected with oscillatory currents, produce effects similar to conventional magnetic mirrors, except at the submicron and nanometre scale. Nanoscale devices present an added complication: very closely placed surfaces can exchange heat through the tunneling of evanescent radiation modes. This can augment the local heating effect when compared to blackbody emission, so any fabrication defects on the surface of the wire spirals could be problematic. We show that the evanescent contributions scale as a function of separation and dominate the heat exchange process when the spacing is much less than the characteristic wavelength of a given temperature. We expect that excess material might be deposited erroneously during fabrication of the spiral wires, so the transfer of heat from one wire coil to the defect will be higher than the rate due to uniform blackbody radiation. In the case of tungsten, for our typical spiral geometry, the heating rate is enhanced by a factor of 15. In the case of a carbon or other high conductivity composite material this rate can be raised by as much as 106, which is evidently not appropriate.

Chang, Mark P. J. L.; Jia, Dongdong; Nazari, Haedeh

2004-08-01

376

Characterization of nanoscale temperature fields during electromigration of nanowires  

PubMed Central

Quantitative studies of nanoscale heat dissipation (Joule heating) are essential for advancing nano-science and technology. Joule heating is widely expected to play a critical role in accelerating electromigration induced device failure. However, limitations in quantitatively probing temperature fields—with nanoscale resolution—have hindered elucidation of the role of Joule heating in electromigration. In this work, we use ultra-high vacuum scanning thermal microscopy to directly quantify thermal fields in nanowires during electromigration. Our results unambiguously illustrate that electromigration begins at temperatures significantly lower than the melting temperature of gold. Further, we show that during electromigration voids predominantly accumulate at the cathode resulting in both local hot spots and asymmetric temperature distributions. These results provide novel insights into the microscopic details of hot spot evolution during electromigration and are expected to guide the design of reliable nanoscale functional devices.

Jeong, Wonho; Kim, Kyeongtae; Kim, Youngsang; Lee, Woochul; Reddy, Pramod

2014-01-01

377

Nanoscale deformation irregularities of ?-irradiated poly(methyl methacrylate)  

NASA Astrophysics Data System (ADS)

Development of deformation jumps in the creep of poly(methyl methacrylate) (PMMA) has been studied. The structural levels of deformation have been determined from the creep rate oscillation periods (deformation jumps) measured by the interferometric method. Special attention is given to a new method of data processing, which enables one to reveal previously undetectable nanoscale deformation jumps. By the example of PMMA specimens preliminarily exposed to ? radiation with doses D=55-330 kGy and unexposed specimens, the presence of nanoscale deformation jumps with the values dependent on the dose D and time of creep has been shown. The obtained results confirm the existence of 10-20-nm domains in amorphous polymers and make it possible to study the multilevel organization of the deformation process, starting from the nanoscale.

Shpe?zman, V. V.; Peschanskaya, N. N.; Yakushev, P. N.; Smolyanski?, A. S.; Shvedov, A. S.; Cheremisov, V. G.

2010-02-01

378

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

379

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

380

Characterization of nanoscale temperature fields during electromigration of nanowires  

NASA Astrophysics Data System (ADS)

Quantitative studies of nanoscale heat dissipation (Joule heating) are essential for advancing nano-science and technology. Joule heating is widely expected to play a critical role in accelerating electromigration induced device failure. However, limitations in quantitatively probing temperature fields--with nanoscale resolution--have hindered elucidation of the role of Joule heating in electromigration. In this work, we use ultra-high vacuum scanning thermal microscopy to directly quantify thermal fields in nanowires during electromigration. Our results unambiguously illustrate that electromigration begins at temperatures significantly lower than the melting temperature of gold. Further, we show that during electromigration voids predominantly accumulate at the cathode resulting in both local hot spots and asymmetric temperature distributions. These results provide novel insights into the microscopic details of hot spot evolution during electromigration and are expected to guide the design of reliable nanoscale functional devices.

Jeong, Wonho; Kim, Kyeongtae; Kim, Youngsang; Lee, Woochul; Reddy, Pramod

2014-05-01

381

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

382

Reverse micelle synthesis of nanoscale metal containing catalysts  

SciTech Connect

The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction and precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni{sub 3}Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.

Darab, J.G.; Fulton, J.L.; Linehan, J.C.

1993-03-01

383

Static and dynamic properties of Fibonacci multilayers  

NASA Astrophysics Data System (ADS)

We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures.

Machado, L. D.; Bezerra, C. G.; Correa, M. A.; Chesman, C.; Pearson, J. E.; Hoffmann, A.

2013-05-01

384

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

385

Plasmonic waveguides with hyperbolic multilayer cladding  

E-print Network

Engineering plasmonic metamaterials with anisotropic optical dispersion enables us to tailor the properties of metamaterial-based waveguides. We investigate plasmonic waveguides with dielectric cores and multilayer metal-dielectric claddings with hyperbolic dispersion. Without using any homogenization, we calculate the resonant eigenmodes of the finite-width cladding layers, and find agreement with the resonant features in the dispersion of the cladded waveguides. We show that at the resonant widths, the propagating modes of the waveguides are coupled to the cladding eigenmodes and hence, are strongly absorbed. By avoiding the resonant widths in the design of the actual waveguides, the strong absorption can be eliminated.

Babicheva, Viktoriia E; Ishii, Satoshi; Boltasseva, Alexandra; Kildishev, Alexander V

2014-01-01

386

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

387

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

388

Optics and multilayer coatings for EUVL systems  

SciTech Connect

EUV lithography (EUVL) employs illumination wavelengths around 13.5 nm, and in many aspects it is considered an extension of optical lithography, which is used for the high-volume manufacturing (HVM) of today's microprocessors. The EUV wavelength of illumination dictates the use of reflective optical elements (mirrors) as opposed to the refractive lenses used in conventional lithographic systems. Thus, EUVL tools are based on all-reflective concepts: they use multilayer (ML) coated optics for their illumination and projection systems, and they have a ML-coated reflective mask.

Soufli, R; Bajt, S; Hudyma, R M; Taylor, J S

2008-03-21

389

A Look Inside Argonne's Center for Nanoscale Materials  

ScienceCinema

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

2014-09-15

390

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

391

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

392

Device Physics of Nanoscale Interdigitated Solar Cells (Poster)  

SciTech Connect

Nanoscale interdigitated solar cell device architectures are being investigated for organic and inorganic solar cell devices. Due to the inherent complexity of these device designs quantitative modeling is needed to understand the device physics. Theoretical concepts have been proposed that nanodomains of different phases may form in polycrystalline CIGS solar cells. These theories propose that the nanodomains may form complex 3D intertwined p-n networks that enhance device performance.Recent experimental evidence offers some support for the existence of nanodomains in CIGS thin films. This study utilizes CIGS solar cells to examine general and CIGS-specific concepts in nanoscale interdigitated solar cells.

Metzger, W.; Levi, D.

2008-05-01

393

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

394

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 ...

395

Breakdown Current Density of CVD-Grown Multilayer Graphene Interconnects  

Microsoft Academic Search

Graphene wires have been fabricated from large-area multilayer graphene sheets grown by chemical vapor deposition. As the methane concentration increases, a larger percentage of thicker graphene layers are grown. The multilayer graphene sheets have an average thickness of 10-20 nm with sheet resistances between 500 and 1000 ?\\/sq. The sheet resistance shows a strong correlation with the average surface roughness.

Kyeong-Jae Lee; Anantha P. Chandrakasan; Jing Kong

2011-01-01

396

Electron beam enhanced multilayering and planarization in preimidized polyimides  

Microsoft Academic Search

High-density packaging and interconnection applications frequently involve the use of polyimide-based materials as interlevel dielectrics for multilevel interconnection schemes. Surface planarity after each polymer layer is very important to the fabrication of multilayer structures. Highly nonplanar surfaces were observed in a multilayer test structure, fabricated using a thermally cured polyimide (Ultradel 7501). In this study, the effect of a novel

Rahul Manepalli; Daniel J. Kovach; Kimberly Farnsworth; Punit Chiniwalla; Brian Dusch; S. A. Bidstrup-Allen; P. A. Kohl

2001-01-01

397

Protein-inspired multilayer nanofilms: science, technology and medicine  

Microsoft Academic Search

The field of polypeptide multilayer nanofilm research flourishes where study of protein structure and function shares a border with development of polyelectrolyte multilayers. The soil is fertile for creative input and promises a harvest of interesting results: the structure of a film can be predetermined on a layer-by-layer (LBL) basis, a huge variety of polypeptide sequences can be realized in

Donald T. Haynie; Ling Zhang; Wanhua Zhao; Jai S. Rudra

2006-01-01

398

Bi-phase transition diagrams of metallic thin multilayers  

SciTech Connect

Phase transitions of metallic multilayers induced by differences in interface energy are considered thermodynamically, based on a thermodynamic model for interface energy and the Goldschmidt premise for lattice contraction. Bi-phase transition diagrams of Co/Cr, Zr/Nb, Ti/Nb and Ti/Al multilayers are constructed, which are in agreement with experimental results.

Li, J.C. [Key Laboratory of Automobile Materials, Ministry of Education, and Department of Materials Science and Engineering, Jilin University, 142 RenMin Street, Changchun 130025 (China); Liu, W. [Key Laboratory of Automobile Materials, Ministry of Education, and Department of Materials Science and Engineering, Jilin University, 142 RenMin Street, Changchun 130025 (China); Jiang, Q. [Key Laboratory of Automobile Materials, Ministry of Education, and Department of Materials Science and Engineering, Jilin University, 142 RenMin Street, Changchun 130025 (China)]. E-mail: jiangq@jlu.edu.cn

2005-02-01

399

FUNDAMENTALS OF GENERALIZED RIGIDITY MATRICES FOR MULTI-LAYERED MEDIA  

Microsoft Academic Search

Rigidity matrices for multi-layered media are derived for isotropic and ortho- tropic layers by a simple direct procedure which brings to light their fundamental mathematical structure. The method was introduced many years ago by the author in the more general context of dynamics and stability of multi-layers under initial stress. Other earlier results are also briefly recalled such as the

MAURICE A. BIOT

400

Innovative Multilayer Technologies for Active Phased Array Antennas  

Microsoft Academic Search

A high performance organic multilayer structure has been developed and manufactured for an active phased array antenna. The driving factors were cost reduction and high integration. To satisfy these requirements, the same multilayer structure mixing aluminum and Teflon® laminates is used as a mechanical support of microwave functions, RE and DC interconnects, power divider including planar resistors, thermal dissipator, ASIC's

Bernard Ledain; Jean Luc Herblot

1997-01-01

401

A refined model for characterizing x-ray multilayers  

SciTech Connect

The ability to quickly and accurately characterize arbitrary multilayers is very valuable for not only can we use the characterizations to predict the reflectivity of a multilayer for any soft x-ray wavelength, we also can generalize the results to apply to other multilayers of the same type. In addition, we can use the characterizations as a means of evaluating various sputtering environments and refining sputtering techniques to obtain better multilayers. In this report we have obtained improved characterizations for sample molybdenum-silicon and vanadium-silicon multilayers. However, we only examined five crystals overall, so the conclusions that we could draw about the structure of general multilayers is limited. Research involving many multilayers manufactured under the same sputtering conditions is clearly in order. In order to best understand multilayer structures it may be necessary to further refine our model, e.g., adopting a Gaussian form for the interface regions. With such improvements we can expect even better agreement with experimental values and continued concurrence with other characterization techniques. 18 refs., 30 figs., 7 tabs.

Oren, A.L.; Henke, B.L.

1987-12-01

402

Superconducting superlattices and multilayers. Proceedings SPIE Volume 2157  

SciTech Connect

This book is divided into the following sections: layered superconductors 1; HTSC (high-temperature superconductors) multilayers; HTSC superlattices 1; layered superconductors 2; HTSC superlattices 2; and LTSC (low-temperature superconductor) superlattices and multilayers. Separate abstracts were prepared for 38 papers in this book.

Bozovic, I. [ed.] [Varian Associates Inc., Palo Alto, CA (United States). E.H. Ginzton Research Center

1994-12-31

403

Hollow multilayer photonic bandgap fibers for NIR applications  

E-print Network

: Here we report the fabrication of hollow-core cylindrical photonic bandgap fibers with fundamental for hollow PBG fibers. The fibers are drawn from a multilayer preform into extended lengths of fiber. Light codes: (060.2280) Fiber design and fabrication, (230.4170) Multilayers, (160.4670) Optical materials

Bayindir, Mehmet

404

Delamination of multilayer thermal barrier coatings Sung Ryul Choi a  

E-print Network

Delamination of multilayer thermal barrier coatings Sung Ryul Choi a , John W. Hutchinson b,*, A reserved. 1. Introduction Thermal barrier coatings (TBCs) consisting of stabilized zirconia are now Received 11 September 1998; received in revised form 9 March 1999 Abstract Multilayer thermal barrier

Hutchinson, John W.

405

Multilayer Microholographic Optical Data Storage with Two-Photon Recording  

NASA Astrophysics Data System (ADS)

The results of experimental study of multilayer optical memory with two-photon recording and collinear heterodyne reading are presented. The description of the experimental setup for multilayer data recording in the form of microholograms with relative phase modulation is given. The recording and readout of microholograms matrix in 20 layers in undoped lithium tantalate crystal is demonstrated.

Steinberg, Ilya; Shepetkin, Yury; Belikov, Andrey

2013-09-01

406

Piezoelectric polymer multilayer on flexible substrate for energy harvesting.  

PubMed

A piezoelectric polymer multilayer structure formed on a flexible substrate is investigated for mechanical energy harvesting under bending mode. Analytical and numerical models are developed to clarify the effect of material parameters critical to the energy harvesting performance of the bending multilayer structure. It is shown that the maximum power is proportional to the square of the piezoelectric stress coefficient and the inverse of dielectric permittivity of the piezoelectric polymer. It is further found that a piezoelectric multilayer with thinner electrodes can generate more electric energy in bending mode. The effect of improved impedance matching in the multilayer polymer on energy output is remarkable. Comparisons between piezoelectric ceramic multilayers and polymer multilayers on flexible substrate are discussed. The fabrication of a P(VDF-TrFE) multilayer structure with a thin Al electrode layer is experimentally demonstrated by a scalable dip-coating process on a flexible aluminum substrate. The results indicate that it is feasible to produce a piezoelectric polymer multilayer structure on flexible substrate for harvesting mechanical energy applicable for many low-power electronics. PMID:24658732

Zhang, Lei; Oh, Sharon Roslyn; Wong, Ting Chong; Tan, Chin Yaw; Yao, Kui

2013-09-01

407

Multi-layer laminate structure and manufacturing method  

DOEpatents

The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

Keenihan, James R.; Cleereman, Robert J.; Eurich, Gerald; Graham, Andrew T.; Langmaid, Joe A.

2013-01-29

408

Multi-layer laminate structure and manufacturing method  

DOEpatents

The present invention is premised upon a multi-layer laminate structure and method of manufacture, more particularly to a method of constructing the multi-layer laminate structure utilizing a laminate frame and at least one energy activated flowable polymer.

Keenihan, James R. (Midland, MI); Cleereman, Robert J. (Midland, MI); Eurich, Gerald (Merrill, MI); Graham, Andrew T. (Midland, MI); Langmaid, Joe A. (Caro, MI)

2012-04-24

409

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

410

Nanoscale hybrid protein/polymer functionalized materials  

NASA Astrophysics Data System (ADS)

Block copolymer-based membrane technology represents a versatile class of nanoscale materials in which biomolecules, such as membrane proteins, can be reconstituted. Our work has demonstrated the fabrication of large-area, protein- enhanced membranes that possess significant performance improvements in protein functionality. Among its many advantages over conventional lipid-based membrane systems, block copolymers can mimic natural cell biomembrane environments in a single chain, enabling large-area membrane fabrication using methods like Langmuir-Blodgett (LB) deposition, or spontaneous protein-functionalized nano-vesicle formation. The membrane protein, Bacteriorhodopsin (BR), found in Halobacterium Halobium, is a light-actuated proton pump that develops gradients towards the demonstration of coupled functionality with other membrane proteins to effect ATP production, or production of electricity through Bacteriorhodopsin activity-dependent reversal of Cytochrome C Oxidase (COX), found in Rhodobacter Sphaeroides. Using quantum dot-labeled, engineered protein constructs, we have demonstrated large-scale insertion of proteins into block copolymer Langmuir-Blodgett (LB) films as well as measurable pH changes based upon light-actuated proton pumping. Light actuated-activity across the protein-functionalized membrane when fully enclosed in a sol-gel matrix has also been observed using impedance spectroscopy. Initial data has suggested a significant pH change of up to 1.75 in a volume of 100 mL and surface area of 0.317cm2, a level that is capable of powering a number of proton-gradient dependent proteins towards the buildup of a robust, hybrid protein/polymer device. Recent atomic force microscopy studies of the protein-embedded polymer film samples have revealed the formation of protein aggregate-based pattern generation with very uniform torus-shaped rings. Current work focused towards characterizing the effects that various pattern formations can have on the efficiency of protein functionality, as well as film stability in an effort to develop a robust polymer membrane will also be discussed.

Ho, Dean; Chu, Ben; Lee, Hyeseung; Montemagno, Carlo D.

2004-07-01

411

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

412

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

413

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.

414

Co/Mg/X Multilayer Mirrors For the EUV Range  

SciTech Connect

A new material combination namely Co/Mg multilayer designed for optics applications in the EUV range, is reported. Simulations show that reflectivity value of the Co/Mg multilayer can reach a reflectivity of 55% at 25.2 nm (49.2 eV), when the grazing incidence angle is set to 45 deg. and s polarization is considered. The introduction of additional materials, e.g., Y and Zr can improve the reflectivity to 61%. Co/Mg and Co/Mg/B{sub 4}C multilayers have been deposited following the parameters deduced from the simulations. The introduction of a B{sub 4}C barrier layer would in principle increase the multilayer reflectivity to 61%. In fact the reflectivity measurements at 0.154 nm show that the introduction of B{sub 4}C does not improve the structural quality of the multilayers.

Hu, M.-H.; Le Guen, K.; Andre, J.-M.; Jonnard, P.; Zhou, S. K.; Li, H. Ch.; Zhu, J. T.; Wang, Z. S. [Laboratoire de Chimie Physique-Matiere et Rayonnement, Universite Pierre et Marie Curie, CNRS UMR 7614, 11 rue Pierre et Marie Curie, F-75231 Paris Cedex 05 (France); Institute of Precision Optical Engineering, Department of Physics, Tongji University, Shanghai 200092 (China)

2010-04-06

415

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

416

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

417

Heat-Resistant Co-W Catalytic Metals for Multilayer Graphene Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

Multilayer graphene (MLG) is expected to be a low-resistance and high-reliability interconnect material replacing copper (Cu) in nanoscale interconnects. Chemical vapor deposition (CVD) on catalytic metals is expected as a practical method for MLG deposition. To obtain high-quality MLG films without catalyst agglomeration by CVD, heat-resistant Co-W catalytic metals were investigated. The agglomeration of the Co-W catalytic metals was suppressed by increasing the W composition; however, MLG deposition was suppressed at the same time. The effects of W addition on the MLG growth were discussed from the viewpoints of the crystallographic change of the Co-W catalysts and chemical reactions. It was found that the Co grain size was reduced and the fcc Co formation was suppressed by W addition. In addition, graphite formation was supposed to be suppressed by W addition owing to the formation of phases other than fcc Co according to the Co-W-C phase diagram. With the optimum W concentration, MLG crystallinity was improved by high-temperature CVD using the heat-resistant Co-W catalytic metals (0.7 at. %) without agglomeration, compared with that in the case of using pure-Co catalysts.

Ueno, Kazuyoshi; Karasawa, Yusuke; Kuwahara, Satoru; Baba, Shotaro; Hanai, Hitoshi; Yamazaki, Yuichi; Sakuma, Naoshi; Kajita, Akihiro; Sakai, Tadashi

2013-04-01

418

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

419

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

420

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

421

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

422

Autoionization in bulk, multilayer, and monolayer Cr  

NASA Astrophysics Data System (ADS)

Angle-resolution techniques in combination with a tunable synchrotron radiation source are used in resonant photoemission from bulk, multilayer, and monolayer Cr. The striking double-peak structure of the resonant 3p-->3d transition in bulk Cr is found to turn gradually into a single peak when going to a multilayer and eventually to a monolayer of Cr. The evolution of the double peak into a single peak is also confirmed in electron-energy-loss spectra. The constant-initial-state (CIS) spectra of bulk Cr are strongly angle dependent. This is an indication of a multichannel autoionization process in the neighborhood of the M2,3 absorption threshold. We attempt to describe this angle dependence by the empirical Kabachnik-Sazhina two-channel autoionization formula. For describing the two-peak-structure angular dependence in Cr we find the following values for the Fano-profile parameters q and the level widths ?: q1=+0.8, q2=-1.5, ?1=5 eV, and ?2=7 eV. The double-peak structure in the Cr M2,3 resonant transition is found to disappear in high-energy transmission electron-energy-loss spectroscopy of a Cr20Au80 alloy. For comparison reasons angle-integrated resonant photoemission studies were also carried out on vanadium for photon energies around the M2,3 binding energy and only a single peak was detected, in agreement with previously published results.

Bader, S. D.; Zajac, G.; Arko, A. J.; Brodsky, M. B.; Morrison, T. I.; Zaluzec, N.; Zak, J.; Benbow, R. L.; Hurych, Z.

1986-03-01

423

Diffractive coherence in multilayer dielectric gratings  

SciTech Connect

Successful operation of large-scale high-power lasers, such as those in use and planned at LLNL and elsewhere, require optical elements that can withstand extremely high fluences without suffering damage. Of particular concern are dielectric diffraction gratings used for beam sampling and pulse compression. Laser induced damage to bulk dielectric material originates with coupling of the electric field of the radiation to bound electrons, proceeding through a succession of mechanisms that couple the electron kinetic energy to lattice energy and ultimately to macroscopic structural changes (e.g. melting). The constructive interference that is responsible for the diffractive behavior of a grating or the reflective properties of a multilayer dielectric stack can enhance the electric field above values that would occur in unstructured homogeneous material. Much work has been done to model damage to bulk matter. The presence of nonuniform electric fields, resulting from diffractive coherence, has the potential to affect damage thresholds and requires more elaborate theory. We shall discuss aspects of work directed towards understanding the influence of dielectric structures upon damage, with particular emphasis on computations and interpretation of electric fields within dielectric gratings and multilayer dielectric stacks, noting particularly the interference effects that occur in these structures.

Shore, B.W.; Feit, M.D.; Perry, M.D.; Boyd, R.D.; Britten, J.A. [Lawrence Livermore National Lab., CA (United States); Li, Lifeng [Arizona Univ., Tucson, AZ (United States). Optical Sciences Center

1995-05-26

424

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

425

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

426

Symmetric multilayer megampere X-pinch  

SciTech Connect

Raising the power of X-ray emission from an X-pinch by increasing the pinch current to the megampere level requires the corresponding increase in the initial linear mass of the load. This can be achieved by increasing either the number of wires or their diameter. In both cases, special measures should be undertaken to prevent the formation of a complicated configuration with an uncontrolled spatial structure in the region of wire crossing, because such a structure breaks the symmetry of the neck formed in the crossing region, destabilizes plasma formation, and degrades X-ray generation. To improve the symmetry of the wire crossing region, X-pinch configurations with a regular multilayer arrangement of wires in this region were proposed and implemented. The results of experiments with various symmetric X-pinch configurations on the COBRA facility at currents of {approx}1MA are presented. It is shown that an X-pinch with a symmetric crossing region consisting of several layers of wires made of different materials can be successfully used in megampere facilities. The most efficient combinations of wires in symmetric multilayer X-pinches are found in which only one hot spot forms and that are characterized by a high and stable soft X-ray yield.

Shelkovenko, T. A.; Pikuz, S. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); McBride, R. D. [Sandia National Laboratories (United States); Knapp, P. F.; Wilhelm, G. [Cornell University (United States); Sinars, D. B. [Sandia National Laboratories (United States); Hammer, D. A. [Cornell University (United States); Orlov, N. Yu. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2010-01-15

427

Symmetric multilayer megampere X-pinch  

NASA Astrophysics Data System (ADS)

Raising the power of X-ray emission from an X-pinch by increasing the pinch current to the megampere level requires the corresponding increase in the initial linear mass of the load. This can be achieved by increasing either the number of wires or their diameter. In both cases, special measures should be undertaken to prevent the formation of a complicated configuration with an uncontrolled spatial structure in the region of wire crossing, because such a structure breaks the symmetry of the neck formed in the crossing region, destabilizes plasma formation, and degrades X-ray generation. To improve the symmetry of the wire crossing region, X-pinch configurations with a regular multilayer arrangement of wires in this region were proposed and implemented. The results of experiments with various symmetric X-pinch configurations on the COBRA facility at currents of ˜1MA are presented. It is shown that an X-pinch with a symmetric crossing region consisting of several layers of wires made of different materials can be successfully used in megampere facilities. The most efficient combinations of wires in symmetric multilayer X-pinches are found in which only one hot spot forms and that are characterized by a high and stable soft X-ray yield.

Shelkovenko, T. A.; Pikuz, S. A.; McBride, R. D.; Knapp, P. F.; Wilhelm, G.; Sinars, D. B.; Hammer, D. A.; Orlov, N. Yu.

2010-01-01

428

Training multi-layered neural network neocognitron.  

PubMed

This paper proposes new learning rules suited for training multi-layered neural networks and applies them to the neocognitron. The neocognitron is a hierarchical multi-layered neural network capable of robust visual pattern recognition. It acquires the ability to recognize visual patterns through learning. For training intermediate layers of the hierarchical network of the neocognitron, we use a new learning rule named add-if-silent. By the use of the add-if-silent rule, the learning process becomes much simpler and more stable, and the computational cost for learning is largely reduced. Nevertheless, a high recognition rate can be kept without increasing the scale of the network. For the highest stage of the network, we use the method of interpolating-vector. We have previously reported that the recognition rate is greatly increased if this method is used during recognition. This paper proposes a new method of using it for both learning and recognition. Computer simulation demonstrates that the new neocognitron, which uses the add-if-silent and the interpolating-vector, produces a higher recognition rate for handwritten digits recognition with a smaller scale of the network than the neocognitron of previous versions. PMID:23380595

Fukushima, Kunihiko

2013-04-01

429

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

430

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

431

How do liquids confined at the nanoscale influence adhesion?  

Microsoft Academic Search

Liquids play an important role in adhesion and sliding friction. They behave as lubricants in human bodies, especially in the joints. However, in many biological attachment systems they act like adhesives, e.g. facilitating insects to move on ceilings or vertical walls. Here we use molecular dynamics to study how liquids confined at the nanoscale influence the adhesion between solid bodies

C. Yang; U. Tartaglino; B. N. J. Persson

2006-01-01

432

Tg and Cure of a Polycyanurate at the Nanoscale  

NASA Astrophysics Data System (ADS)

Nanoscale constraint is known to have a significant impact on the thermal properties of materials. Although thermosetting resins have been cured in the presence of nanoparticles and nanotubes, cure of thermosetting resins under the well defined nanoscale constraints imposed by controlled pore glass (CPG) or similar matrices has not been previously documented. In this work, we investigate the isothermal curing under nanoscale constraint of a thermosetting resin, bisphenol M dicyanate ester (BMDC), which trimerizes to form a polycyanurate network material. Differential scanning calorimeter is used to monitor the evolution of the glass transition temperature (Tg) and the conversion during cure as a function of the diameter of the silanized control pore glass matrix which is used for confinement. A Tg depression is observed for both the bisphenol M dicyanate ester monomer and the polycyanurate networks; the depression is only a few degrees for the monomer, whereas a 56 K depression is observed for the ``fully-cured'' network in 11.5 nm pores. The nanoscale constraint is also found to accelerate the cure of the bisphenol M dicyanate ester, but it does not affect the normalized Tg versus conversion relationship. The appearance of a secondary Tg above the primary Tg in the smaller pores and the associated length scale are discussed.

Simon, Sindee; Li, Qingxiu

2008-03-01

433

Nanoscale Science: Activities for Grades 6-12  

NSDL National Science Digital Library

Futurists predict that nanotechnology will be the next major scientific revolution--one with an even greater impact than the Industrial Revolution. Nanoscale Science will help your middle and high school students understand the big implications of tiny technology. Using guided inquiry with open-ended exploration where possible, the book's 20 investigations teach students about the unique properties and behavior of materials at the nanoscale--one-billionth of the size of a meter. The activities are organized around five themes: scale, tools and techniques, unique properties and behaviors, nanotechnology applications, and societal implications. All activities use readily available materials and provide clear background, instructions, and formative assessments. They also explore questions sure to engage both students and you, such as: � Just how small is one in a billion? � How might manipulating matter at the nanoscale lead to everything from stain-resistant fabrics to improved means to clean water to tumor-targeting nanoshells? � And how will society change when we use nanolabels to track where people, animals, and materials move around the world? For the first time in human history, we have the ability to manipulate and build materials from the atom up. NanoScale Science --written by experts at developing effective ways to teach about nanotechnology--is a pioneering instructional guide to this important subject. Use it as a fascinating supplement to studies of biology, physics, chemistry, math, and the environment.

Taylor, Amy R.; Broadwell, Bethany P.; Jones, M. G.; Falvo, Michael R.

2007-01-01

434

High yield synthesis and processing of nanoscale YTZP ceramics  

Microsoft Academic Search

Nanomaterials are the subject of increasing interest. The expectation of new and enhanced mechanical, optical, magnetic, and electronic properties, in part due to the high concentration of interfaces and grain boundaries within the nanoscale microstructure, has initiated many studies on how to synthesize materials and process components with a final grain size below 100 nm. Several obstacles have hindered the

Christopher J. Szepesi

2010-01-01

435

Solving time-dependent operator equations for nanoscale physics  

SciTech Connect

This is the final technical report on an Office of Basic Energy Sciences Grant, detailing the work accomplished on solving time-dependent operator equations of interest in nanoscale physics. A summary of the results and list of publications is given.

Rau, A. Ravi P.

2007-08-27

436

Optical methodology for detecting histologically unapparent nanoscale consequences of genetic  

E-print Network

Optical methodology for detecting histologically unapparent nanoscale consequences of genetic Tafloveb , and Vadim Backmana,1 Departments of aBiomedical Engineering and bElectrical Engineering of the potential of the technique, in the experiments with cell lines and an animal model of colon carcinogenesis

Ottino, Julio M.

437

Ion-stimulated mass transport in nanoscale morphology evolution  

E-print Network

Bola George to The School of Engineering and Applied Sciences in partial fulfillment Cambridge, Massachusetts April 2007 #12;©2007 ­ Henry Bola George All rights reserved. #12;Author: Henry Bola George Abstract Thesis advisor: Michael J. Aziz Ion-stimulated mass transport in nanoscale

438

Recent advances in superhydrophobic nanomaterials and nanoscale systems.  

PubMed

This review describes the recent advances in the field of superhydrophobic nanomaterials and nanoscale systems. The term superhydrophobic is defined from the surface properties when the surface shows the contact angle (CA) higher than 150 degrees. This could be well known from the lotus effect due to the non-stick and self-cleaning properties of the lotus leaf (LL). We briefly introduced the methods of preparing superhydrophobic surfaces using top-down approaches, bottom-up approaches and a combination of top-down and bottom-up approaches and various ways to prepare superhydrophobic nanomaterials and nanoscale systems using the bio-inspired materials, polymer nanocomposites, metal nanoparticles graphene oxide (GO) and carbon nanotubes (CNTs). We also pointed out the recent applications of the superhydrophobic nanomaterials and nanoscale systems in oil-spill capture and separations, self-cleaning and self-healing systems, bio-medicals, anti-icing and anti-corrosive, electronics, catalysis, textile fabrics and papers etc. The review also highlights the visionary outlook for the future development and use of the superhydrophobic nanomaterials and nanoscale systems for a wide variety of applications. PMID:24749434

Nagappan, Saravanan; Park, Sung Soo; Ha, Chang-Sik

2014-02-01

439

Novel Nanoscale Materials Reduce Electricity Needed for Sludge  

E-print Network

Novel Nanoscale Materials Reduce Electricity Needed for Sludge Dewatering Industrial in California is 2 billion kilowatthours per year. Part of sludge treatment includes dewatering, a process that removes as much water from digested sludge as possible. Dewatering is necessary to reduce the sludge

440

Performance comparison of artificial intelligence networks in nanoscale MOSFET modeling  

Microsoft Academic Search

In this paper, different types of artificial intelligence networks were compared in order to simulate the nonlinear behavior of nanoscale MOSFETs. The accuracy of the approaches in determining the device drain current and the training time were discussed. The training data was generated in Hspice environment and imported in Matlab7.5 for simulation. Finally, optimized structures for accurate and fast device

Amir Hossein Abdollahi Nohoji; Fardad Farokhi; Majid Zamani

2011-01-01

441

Nanoscale germanium MOS Dielectrics-part I: germanium oxynitrides  

Microsoft Academic Search

In this paper, nanoscale germanium (Ge) oxynitride dielectrics are investigated for Ge MOS device applications. The synthesizing methodology and physical properties of these oxynitride films have been examined first. Basic electrical characteristics have been acquired on metal-gated MOS capacitors with Ge oxynitride dielectric on substrates with different dopant types and crystal orientations. Using an optimized oxidation and nitridation recipe, high-quality

Chi On Chui; F. Ito; K. C. Saraswat

2006-01-01

442