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1

The properties of amylose-ethylcellulose films cast from organic-based solvents as potential coatings for colonic drug delivery.  

PubMed

The purpose of the study was to establish the physico-mechanical and digestibility properties of water-miscible organic solvent-based amylose-ethylcellulose films as potential coatings for colonic drug delivery. Free films containing different ratios of amylose to ethylcellulose were cast from the water-miscible organic solvent, ethyl lactate, in combination with the plasticiser, dibutyl sebacate. The resultant mixed films were characterised in terms of tensile strength and elasticity, polymer miscibility, permeability, and digestibility under simulated colonic conditions. Films containing higher concentrations of amylose displayed increasing weakness and softness and faster permeation to hydrogen ions compared to films with lower amylose content. No apparent miscibility was detected between the amylose and ethylcellulose, regardless of film composition. The films were found to be susceptible to digestion by bacterial enzymes within a simulated colonic environment. The extent of digestion was directly proportional to the amount of amylose present within the film. Overall, the results suggest that such amylose-ethylcellulose films could be used as coatings for drug delivery to the colon. PMID:10915961

Siew, L F; Basit, A W; Newton, J M

2000-08-01

2

Some properties of films cast from polyurethane aqueous dispersions of polyether-based anionomer extended with hydrazine  

Microsoft Academic Search

Polyurethanes as aqueous dispersions were synthesized and some mechanical properties of the casted films were analysed. Anionomers prepolymers were prepared in bulk by the reaction of poly(propylene oxide), 4,4?-dicyclohexylmethane diisocyanate and dimethylolpropionic acid. The acid group's neutralization was carried out with triethylamine. The prepolymer was divided into two parts and to one of them acetone was added. The prepolymer was

F. M. B. Coutinho; M. C. Delpech

1996-01-01

3

Thermal and mechanical profile of cast films from waterborne polyurethanes based on polyether block copolymers  

Microsoft Academic Search

Environmental considerations have been the cause of increasing research and development of waterborne polymer systems for\\u000a many different applications, particularly as coatings for several kinds of substrates. In this work, waterborne polyurethanes\\u000a (WPU) based on block copolymers of ethylene glycol and propylene glycol (EG-b-PG), with 25% of EG segments, poly(propylene\\u000a glycol), dimethylolpropionic acid, isophorone diisocyanate, and hydrazine, as chain extender,

Cristiane C. Santos; Marcia C. Delpech; Fernanda M. B. Coutinho

2009-01-01

4

Melting and casting of FeAl-based cast alloy  

SciTech Connect

The FeAl-based intermetallic alloys are of great interest because of their low density, low raw material cost, and excellent resistance to high-temperature oxidation, sulfidation, carburization, and molten salts. The applications based on these unique properties of FeAl require methods to melt and cast these alloys into complex-shaped castings and centrifugal cast tubes. This paper addresses the melting-related issues and the effect of chemistry on the microstructure and hardness of castings. It is concluded that the use of the Exo-Melt{trademark} process for melting and the proper selection of the aluminum melt stock can result in porosity-free castings. The FeAl alloys can be melted and cast from the virgin and revert stock. A large variation in carbon content of the alloys is possible before the precipitation of graphite flakes occurs. Titanium is a very potent addition to refine the grain size of castings. A range of complex sand castings and two different sizes of centrifugal cast tubes of the alloy have already been cast.

Sikka, V.K. [Oak Ridge National Lab., TN (United States); Wilkening, D. [Columbia Falls Aluminum Co., Columbia Falls, MT (United States); Liebetrau, J.; Mackey, B. [AFFCO, L.L.C., Anaconda, MT (United States)

1998-11-01

5

Oxygen permeability of cast ionomer films from chronoamperometry on microelectrodes  

NASA Astrophysics Data System (ADS)

The paper presents a method for determination of diffusion coefficient and solubility of oxygen in cast polymer electrolyte from chronoamperometry of oxygen on polymer electrolyte coated platinum disk ultramicroelectrodes. The approach is based on numerical fitting of measured currents to the known but not previously used for polymer electrolytes equation derived by Shoup and Szabo. The method was applied to cast films of a novel polymer electrolyte 6F-40. As opposed to Nafion®, cast 6F-40 films do not undergo interfacial restructuring, i.e., they retain their original morphology under selected temperature and humidity conditions, which allows for accurate determination of both parameters from measurements for a range of electrode radii and film thicknesses. It is demonstrated that the Shoup and Szabo equation satisfactorily describes measured current transients for shorter oxygen reduction times, i.e., when the diffusion field in the thin polymer film can be regarded as semiinfinite. The accuracy of the diffusion coefficient and solubility determinations was not measurably affected by the product water and the observed systematic changes of the fit quality in various time domains were attributed to approximate character of the fitting equation.

Chlistunoff, Jerzy

2014-01-01

6

Fractal structures in casting films from chlorophyll  

NASA Astrophysics Data System (ADS)

Chlorophyll (Chl) molecules are important because they can act as natural light-harvesting devices during the photosynthesis. In addition, they have potential for application as component of solar cell. In this work, we have prepared casting films from chlorophyll (Chl) and demonstrated the occurrence of fractal structures when the films were submitted to different concentrations. By using optical microscopy and the box-count method, we have found that the fractal dimension is Df = 1.55. This value is close to predicted by the diffusion-limited aggregation (DLA) model. This suggests that the major mechanism - which determines the growth of the fractal structures from Chl molecules - is the molecular diffusion. Since the efficiencies of solar cells depend on the morphology of their interfaces, these finds can be useful to improve this kind of device.

Pedro, G. C.; Gorza, F. D. S.; de Souza, N. C.; Silva, J. R.

2014-04-01

7

Land-based turbine casting initiative  

SciTech Connect

To meet goals for the ATS program, technical advances developed for aircraft gas turbine engines need to be applied to land-based gas turbines. These advances include directionally solidified and single crystal castings, alloys tailored to exploit these microstructures, complex internal cooling schemes, and coatings. The proposed program to scale aircraft gas turbine casting technology up to land based gas turbine size components is based on low sulfur alloys, casting process development, post-cast process development, and establishing casting defect tolerance levels. The inspection side is also discussed.

Mueller, B.A.; Spicer, R.A. [Howmet Corp., Whitehall, MI (United States)

1995-12-31

8

Tensile properties of free films cast from aqueous ethylcellulose dispersions.  

PubMed

Free films of two commercially available formulations of aqueous ethylcellulose dispersion differing only in plasticizer content (Sure-lease/E-7-7050 without silica and E-7-7060 containing dibutyl sebacate and glyceryl tricaprylate/caprate as plasticizers, respectively) were cast and coalesced at temperatures ranging between 30 and 70 degrees C. Mechanical properties of these films were measured using tensile stress analysis. Three mechanical parameters, namely, tensile strength, work of failure, and elastic modulus, were computed from the load-time profiles of these films. The results showed that the tensile strength and elastic modulus values of the films cast from both formulations increased with the corresponding increase in coalescence temperature up to 60 degrees C, beyond which no significant differences were observed. In the case of work of failure, however, the difference between the two formulations was observed above 60 degrees C. The films cast from Surelease/E-7-7050 formulation without silica (dibutyl sebacate as the plasticizer) were relatively softer than those from Surelease/E-7-7060 formulation (glyceryl tricaprylate/caprate as the plasticizer). At coalescence temperatures above 50 degrees C, the films cast from both formulations exhibited temperature-dependent plastic deformation. PMID:8321847

Parikh, N H; Porter, S C; Rohera, B D

1993-06-01

9

CAST  

NSDL National Science Digital Library

The Council for Agricultural Science and Technology (CAST) was formed in 1972 as a result of a meeting sponsored by the National Academy of Sciences' National Research Council. CAST's mission is to "assemble, interpret, and communicate credible science-based information regionally, nationally, and internationally to legislators, regulators, policymakers, the media, the private sector and the public." Visitors will find the Education tab near the top of the page to be particularly helpful for those who want to pursue agricultural careers or learn about agricultural education, such as 4-H or Future Farmers of America. The CAST Videos section has a number of PowerPoint presentations on current topics of importance in agriculture, such as "The Science and Regulation of Food from Genetically Engineered Animals," "Food Safety and Fresh Produce," and "Probiotics in Human Health." A number of the papers that accompany the PowerPoint presentations are available for free.

2012-02-06

10

CAST  

NSDL National Science Digital Library

The Council for Agricultural Science and Technology (CAST) was formed in 1972 as a result of a meeting sponsored by the National Academy of Sciences' National Research Council. CAST's mission is to "assemble, interpret, and communicate credible science-based information regionally, nationally, and internationally to legislators, regulators, policymakers, the media, the private sector and the public." Visitors will find the Education tab near the top of the page to be particularly helpful for those who want to pursue agricultural careers or learn about agricultural education, such as 4-H or Future Farmers of America. The CAST Videos section has a number of PowerPoint presentations on current topics of importance in agriculture, such as "The Science and Regulation of Food from Genetically Engineered Animals," "Food Safety and Fresh Produce," and "Probiotics in Human Health." A number of the papers that accompany the PowerPoint presentations are available for free.

2012-02-03

11

Understanding how processing additives tune nanoscale morphology of high efficiency organic photovoltaic blends: From casting solution to spun-cast thin film  

SciTech Connect

Adding a small amount of a processing additive to the casting solution of organic blends has been demonstrated to be an effective method for achieving improved power conversion efficiency (PCE) in organic photovoltaics (OPVs). However, an understanding of the nano-structural evolution occurring in the transformation from casting solution to thin photoactive films is still lacking. In this report, we investigate the effects of the processing additive diiodooctane (DIO) on the morphology of OPV blend of PBDTTT-C-T and fullerene derivative, PC71BM in a casting solution and in spun-cast thin films by using neutron/x-ray scattering, neutron reflectometry and other characterization techniques. The results reveal that DIO has no effect on the solution structures of PBDTTT-C-T and PC71BM. In the spun-cast films, however, DIO is found to promote significantly the molecular ordering of PBDTTT-C-T and PC71BM, and phase segregation, resulting in the improved PCE. Thermodynamic analysis based on Flory-Huggins theory provides a rationale for the effects of DIO on different characteristics of phase segregation as a solvent and due to evaporationg during the film formation. Such information may enable improved rational design of ternary blends to more consistently achieve improved PCE for OPVs.

Shao, Ming [ORNL; Keum, Jong Kahk [ORNL; Kumar, Rajeev [ORNL; Chen, Jihua [ORNL; Browning, Jim [ORNL; Chen, Wei [Argonne National Laboratory (ANL); Jianhui, Hou [Chinese Academy of Sciences (CAS), Institute of Chemistry; Do, Changwoo [ORNL; Littrell, Ken [ORNL; Sanjib, Das [University of Tennessee, Knoxville (UTK); Rondinone, Adam Justin [ORNL; Geohegan, David B [ORNL; Sumpter, Bobby G [ORNL; Xiao, Kai [ORNL

2014-01-01

12

Surface Oxide Film Entrainment Mechanisms in Shape Casting Running Systems  

NASA Astrophysics Data System (ADS)

During the transient phase of filling a casting running system, surface turbulence can cause the entrainment of oxide films into the bulk liquid. Research has shown that these are detrimental to the material’s integrity. Common mechanisms for this entrainment include returning waves, arising during filling of the runner bar, and plunging jets, found when pouring into a basin. One of these, the returning wave, has been studied in greater depth, using real-time X-ray and process modeling techniques alongside the application of physical principals. It has been concluded that when developed, returning waves cannot attain the more stable and less entraining tranquil flow regime desirable in the running system of castings.

Reilly, C.; Green, N. R.; Jolly, M. R.

2009-12-01

13

Study of anisotropy of spin cast and vapor deposited polyimide films using internal reflection techniques  

SciTech Connect

We have compared anisotropy of spin cast and vapor deposited polyimide (VDP) films, using internal reflection infrared spectroscopy. The films were deposited directly on the internal reflection element. We find that spin cast films are more anisotropic than their VDP counterparts, with the polyimide chains tending to align parallel to the substrate. Both films are found to contain more and less ordered regions. Within the ordered regions, the plane of the phenyl ring tends to align parallel to the substrate.

Liberman, V.

1996-11-01

14

High-performance amperometric biosensors and biofuel cell based on chitosan-strengthened cast thin films of chemically synthesized catecholamine polymers with glucose oxidase effectively entrapped  

Microsoft Academic Search

Rapid oxidation of dopamine (DA) or l-noradrenaline (NA) by K3Fe(CN)6 yields poly(DA) (PDAC) or poly(NA) (PNAC) with glucose oxidase (GOx) effectively entrapped, and such an enzyme-entrapped catecholamine polymer is cast on an Au electrode followed by chitosan (CS) strengthening for biosensing and fabrication of a biofuel cell (BFC). The optimized glucose biosensor of CS\\/PDAC–GOx\\/Au displays an extremely high sensitivity up

Chao Chen; Lihua Wang; Yueming Tan; Cong Qin; Fangyun Xie; Yingchun Fu; Qingji Xie; Jinhua Chen; Shouzhuo Yao

2011-01-01

15

Stability of cast-film extrusion of various metallocene polyethylenes R. Bouamra, J.F. Agassant, C. Peiti and J.M. Haudin  

E-print Network

Stability of cast-film extrusion of various metallocene polyethylenes R. Bouamra, J.F. Agassant, C, France 1- Introduction The Cast Film process is one of the most widely used polymer processing technology: General view of (a) the Cast Film process, (b) the Cemef experimental device The cast film process may

Paris-Sud XI, Université de

16

Electroconductive PET/SWNT Films by Solution Casting  

NASA Technical Reports Server (NTRS)

The market for electrically conductive polymers is rapidly growing, and an emerging pathway for attaining these materials is via polymer-carbon nanotube (CNT) nanocomposites, because of the superior properties of CNTs. Due to their excellent electrical properties and anisotropic magnetic susceptibility, we expect CNTs could be easily aligned to maximize their effectiveness in imparting electrical conductivity to the polymer matrix. Single-walled carbon nanotubes (SWNT) were dispersed in a polyethylene terephthalate (PET) matrix by solution blending then cast onto a glass substrate to create thin, flexible films. Various SWNT loading concentrations were implemented (0.5, 1.0, and 3.0 wt.%) to study the effect of additive density. The processing method was repeated to produce films in the presence of magnetic fields (3 and 9.4 Tesla). The SWNTs showed a high susceptibility to the magnetic field and were effectively aligned in the PET matrix. The alignment was characterized with Raman spectroscopy. Impedance spectroscopy was utilized to study the electrical behavior of the films. Concentration and dispersion seemed to play very important roles in improving electrical conductivity, while alignment played a secondary and less significant role. The most interesting result proved to be the effect of a magnetic field during processing. It appears that a magnetic field may improve dispersion of unmodified SWNTs, which seems to be more important than alignment. It was concluded that SWNTs offer a good option as conductive, nucleating filler for electroconductive polymer applications, and the utilization of a magnetic field may prove to be a novel method for CNT dispersion that could lead to improved nanocomposite materials.

Steinert, Brian W.; Dean, Derrick R.

2008-01-01

17

Characterization of Bimetallic Castings with an Austenitic Working Surface Layer and an Unalloyed Cast Steel Base  

NASA Astrophysics Data System (ADS)

The paper presents the technology of bimetallic castings based on the founding method of layer coating directly in the cast process of the so-called method of mold cavity preparation. The prepared castings consist of two fundamental parts, i.e., the base and the working surface layer. The base part of the bimetallic casting is typical foundry material, i.e., unalloyed cast steel, whereas the working layer is a plate of austenitic alloy steel sort X2CrNi 18-9. The quality of the joint between the base part and the working layer was evaluated on the basis of ultrasonic non-destructive testing and structure examinations containing metallographic macro- and microscopic studies with the use of a light microscope (LOM) with microhardness measurements and a scanning electron microscope (SEM) with microanalysis of the chemical composition (energy dispersive spectroscopy—EDS). On the basis of the obtained results it was confirmed that the decisive phenomena needed to create a permanent joint between the two components of the bimetallic casting are carbon and heat transport in the direction from the high-carbon and hot base material which was poured into the mold in the form of liquid metal to the low-carbon and cold material of the working layer which was placed in the mold cavity in the form of a monolithic insert.

Wróbel, Tomasz

2014-05-01

18

Oxide films, pores and the fatigue lives of cast aluminum alloys  

NASA Astrophysics Data System (ADS)

In the absence of gross defects such as cold shuts, the fatigue properties of castings are largely determined by the sizes of microstructural defects, particularly pores and oxide films. In contrast, the effects of grain size, second-phase particles, and nonmetallic inclusions are insignificant. The authors review the fatigue properties of castings made by gravity die casting, sand casting, lost-foam casting, squeeze casting, and semisolid casting, and compare A356/357 alloys with 319-type alloys. The application of fracture mechanics enables the properties to be rationalized in terms of the defects that are characteristic of each casting process, noting both the sizes and types of defect. The differences in the properties of castings are entirely attributed to their different defect populations. No single process is inherently superior. For defects of the same size (in terms of projected area normal to the loading direction), oxide films are less detrimental to fatigue life than pores. Areas of current controversy are highlighted and suggestions for further work are made.

Wang, Q. G.; Crepeau, P. N.; Davidson, C. J.; Griffiths, J. R.

2006-12-01

19

RELIABILITY-BASED CASTING PROCESS DESIGN OPTIMIZATION  

E-print Network

in a purely deterministic approach, replacing iterative trial-and- error process development on the shop floor system optimization. In optimization of the casting feeding system, optimal sizes and locations

Beckermann, Christoph

20

Effect of casting solvent on crystallinity of ondansetron in transdermal films.  

PubMed

The purpose of the present investigation is to assess the influence of casting solvent on crystallinity of ondansetron hydrochloride in transdermal polymeric matrix films fabricated using povidone and ethyl cellulose as matrix forming polymers. Various casting solvents like chloroform (CHL), dichloromethane (DCM), methanol (MET); and mixture of chloroform and ethanol (C-ETH) were used for fabrication of the transdermal films. Analytical tools like scanning electron microscopy (SEM), X-ray diffraction (XRD) studies, differential scanning calorimetry (DSC), etc. were utilized to characterize the crystalline state of ondansetron in the film. Recrystallisation was observed in all the transdermal films fabricated using the casting solvents other than chloroform. Long thin slab-looking, long wire-like or spherulite-looking crystals with beautiful impinged boundaries were observed in SEM. Moreover, XRD revealed no crystalline peaks of ondansetron hydrochloride in the transdermal films prepared using chloroform as casting solvent. The significantly decreased intensity and sharpness of the DSC endothermic peaks corresponding to the melting point of ondansetron in the formulation (specifically in CHL) indicated partial dissolution of ondansetron crystals in the polymeric films. The employed analytical tools suggested chloroform as a preferred casting solvent with minimum or practically absence of recrystallization indicating a relatively amorphous state of ondansetron in transdermal films. PMID:21237257

Pattnaik, Satyanarayan; Swain, Kalpana; Mallick, Subrata; Lin, Zhiqun

2011-03-15

21

Grain Refinement of Permanent Mold Cast Copper Base Alloys  

SciTech Connect

Grain refinement is a well established process for many cast and wrought alloys. The mechanical properties of various alloys could be enhanced by reducing the grain size. Refinement is also known to improve casting characteristics such as fluidity and hot tearing. Grain refinement of copper-base alloys is not widely used, especially in sand casting process. However, in permanent mold casting of copper alloys it is now common to use grain refinement to counteract the problem of severe hot tearing which also improves the pressure tightness of plumbing components. The mechanism of grain refinement in copper-base alloys is not well understood. The issues to be studied include the effect of minor alloy additions on the microstructure, their interaction with the grain refiner, effect of cooling rate, and loss of grain refinement (fading). In this investigation, efforts were made to explore and understand grain refinement of copper alloys, especially in permanent mold casting conditions.

M.Sadayappan; J.P.Thomson; M.Elboujdaini; G.Ping Gu; M. Sahoo

2005-04-01

22

DETAIL VIEW OF BASE OF CAST IRON TOWER SHOWING THE ...  

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

DETAIL VIEW OF BASE OF CAST IRON TOWER SHOWING THE FABRICATING MARK OF STARBUCK IRON WORKS, TROY, NY - Bidwell Bar Suspension Bridge & Stone Toll House, Near Lake Oroville (moved from fork of Feather River), Oroville, Butte County, CA

23

Adaptive GPU Ray Casting Based on Spectral Stefan Suwelack1  

E-print Network

Adaptive GPU Ray Casting Based on Spectral Analysis Stefan Suwelack1 , Eric Heitz1 Roland Laboratories (HIS), Karlsruhe Institute of Technology (KIT), Germany, suwelack@kit.edu Abstract. GPU based ray that the rendering speed of the GPU implementation is greatly increased with reference to the non-adaptive algorithm

Paris-Sud XI, Université de

24

Study on theoretical bases of receiving composite alloy layers on surface of cast steel castings  

Microsoft Academic Search

The use of composite alloy layers on chosen surfaces of cast makes possible to obtain a special usable properties. Composite alloy layers on cast steel shapes with liquid phase. The processes which set in form during formation of composite layer, progress beside the transient heat flow that the transient thermal field. Decrease of temperature in surface layer of cast causes

J. Gawro?ski; J. Szajnar; P. Wróbel

2004-01-01

25

Phase-transitions in Langmuir-Blodgett and cast films of a ferroelectric liquid crystal.  

PubMed

Langmuir-Blodgett films and cast films of a ferroelectric liquid crystal of sec-butyl-6-(4-(nonyloxy)benzoyloxy)-2-naphthoate have been fabricated. Their thermal behavior was investigated using infrared spectroscopy at elevated temperature combined with principal component analysis. The result shows a new phase transition from smectic A to nematic phase, compared to the phase sequence obtained by polarizing optical microscopy. Another solid transition of different isomeric crystals was also found, which was confirmed by calorimetric measurement. PMID:17625316

Wen, Zi; Jiang, Qing; DU, Yiping; Ozaki, Yukihiro

2007-07-01

26

Fluid casting of particle-based articles  

DOEpatents

A method is disclosed for the production of articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is introduced into an immiscible, heated fluid. The slurry sets hardens into a shape determined by the physical characteristics of the fluid and the manner of introduction of the slurry into the fluid. For example, the slurry is pulse injected into the fluid to provide spherical articles. The hardened spheres may then be sintered to consolidate the particles and provide a high density product. 1 figure.

Menchhofer, P.

1995-03-28

27

Magnetoresistance of drop-cast film of cobalt-substituted magnetite nanocrystals.  

PubMed

An oleic acid-coated Fe2.7Co0.3O4 nanocrystal (NC) self-assembled film was fabricated via drop casting of colloidal particles onto a three-terminal electrode/MgO substrate. The film exhibited a large coercivity (1620 Oe) and bifurcation of the zero-field-cooled and field-cooled magnetizations at 300 K. At 10 K, the film exhibited both a Coulomb blockade due to single electron charging as well as a magnetoresistance of ?-80% due to spin-dependent electron tunneling. At 300 K, the film also showed a magnetoresistance of ?-80% due to hopping of spin-polarized electrons. Enhanced magnetic coupling between adjacent NCs and the large coercivity resulted in a large spin-polarized current flow even at 300 K. PMID:25259873

Kohiki, Shigemi; Nara, Koichiro; Mitome, Masanori; Tsuya, Daiju

2014-10-22

28

Casting of particle-based hollow shapes  

DOEpatents

A method is disclosed for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product. 9 figs.

Menchhofer, P.

1997-09-09

29

Casting of particle-based hollow shapes  

DOEpatents

A method is disclosed for the production of hollow articles made of a particle-based material; e.g., ceramics and sintered metals. In accordance with one aspect of the invention, a thermally settable slurry containing a relatively high concentration of the particles is coated onto a prewarmed continuous surface in a relatively thin layer so that the slurry is substantially uniformly coated on the surface. The heat of the prewarmed surface conducts to the slurry to initiate a reaction which causes the slurry to set or harden in a shape conforming to the surface. The hardened configurations may then be sintered to consolidate the particles and provide a high density product. 9 figs.

Menchhofer, P.

1995-05-30

30

Application of a tungsten/tungsten-carbide film to H-13 casting dies by plasma assisted deposition  

SciTech Connect

Die casting is used extensively to produce Al, Mg and Zn alloy parts. H-13, a widely used die material, is a medium carbon steel alloy with Cr, Mo, and Si. A problem with die casting is soldering, thermal fatigue cracking, and carbon buildup which cause degradation of the casting. Application of a metallic coating to the die has been shown to increase the resistance to thermal fatigue cracking. In this study, a tungsten/tungsten carbide thin film was deposited on a casting die of H-13 die steel by a two step Plasma Source Ion Enhanced Deposition process using an argon and methane plasmas. The film was characterized using Auger Electron Spectroscopy, Scanning Electron Microscopy and Electron Dispersive Spectroscopy. The die and representative castings (from regular intervals during the lifetime of the die) were examined for evidence of soldering, thermal fatigue cracking and carbon buildup.

Horswill, N.; Jetzer, W.; Fetherston, P.; Conrad, J.R. [Univ. of Wisconsin, Madison, WI (United States)

1995-12-31

31

Structural and orientational studies of chiral N-[4(1-pyrene)butyroyl]-phenylalanine in cast film  

NASA Astrophysics Data System (ADS)

Cast films of chiral material N-[4(1-pyrene)butyroyl]- L-phenylalanine (Py- L-Phe) and the racemic modification (the 1:1 mixture of Py- L-Phe and Py- D-Phe) have been investigated in the present study. The microscopic structure, molecular orientation and the aggregation in the film have been studied by using ultraviolet-visible (UV-vis) and infrared (IR) spectroscopy. When a cast film is formed from the chloroform solution at room temperature, the J-aggregates of Py- L-Phe and Py- D-Phe are observed by UV-vis spectra. A comparison of Fourier transform infrared (FT-IR) transmission and reflection-absorption (RA) spectroscopy has been applied to reveal the orientation and structural characterization of the cast films. It has been found that the pyrenyl ring in the cast film of Py- L-Phe assumes a nearly vertical orientation with respect to the surface of the solid substrate. And there are two different hydrogen bonding species, cyclic dimer and linear dimer, exist in carboxyl groups in cast films. The detailed analysis of the O sbnd H and N sbnd H stretching modes of Py- L-Phe and Py- D-Phe allows us to reveal the hydrogen bonds existing in the films.

Zhai, Chunxi; Li, Wen; Ma, Lijun; Wu, Lixin; Wu, Yuqing

2005-09-01

32

Miniaturized pattern formation in elastic films cast on sinusoidally patterned substrates.  

PubMed

The various morphologies that are formed when van der Waals forces or electric field is induced between film cast on a sinusoidal substrate and in contact proximity with a contactor or electrode are studied. Remarkably smaller length scales are achieved (?c < 2.96h) than those obtained with films cast on flat substrates. With van der Waals interactions, the patterns are uniformly formed throughout the film but are not regularly ordered. When electric field is used at critical voltage, more ordered, localized patterns are formed at the zones of large local interaction strengths. When these patterns are evolved by increasing the applied voltage, coexistence of all three phases-cavities, stripes, and columns-is observed throughout the film. The localized patterns that are initially formed vary with the voltage applied and strongly dictate the phases of evolution. A patterned substrate/patterned contactor assembly can be made to operate like its unpatterned counterpart by making the interaction strength same everywhere and yet yield uniform, regularly ordered, highly miniaturized patterns. Such patterns are very useful in various applications like microfluidics; they are formed with great ease and can be morphologically tuned by tuning the externally applied electric field. PMID:25238212

Annepu, Hemalatha; Sarkar, Jayati

2014-10-21

33

A Role Casting Method Based on Emotions in a Story Generation System  

E-print Network

A Role Casting Method Based on Emotions in a Story Generation System Ruck Thawonmas1 , Masanao point out a problem in the role casting method of a story generation system called OPIATE and then propose a solution to this problem. The existing casting method does not take into account the emotions

Thawonmas, Ruck

34

Tensile Behavior of Fabric Cement-Based Composites: Pultruded and Cast  

E-print Network

Tensile Behavior of Fabric Cement-Based Composites: Pultruded and Cast A. Peled1 and B. Mobasher2 processing methods, casting and pultrusion, on the tensile properties of fabric-cement composites. Four after casting. Pressed composites showed an increase in flexural strength but a reduction

Mobasher, Barzin

35

Crystallographic Textures and Morphologies of Solution Cast Ibuprofen Composite Films at Solid Surfaces  

PubMed Central

The preparation of thin composite layers has promising advantages in a variety of applications like transdermal, buccal, or sublingual patches. Within this model study the impact of the matrix material on the film forming properties of ibuprofen–matrix composite films is investigated. As matrix materials polystyrene, methyl cellulose, or hydroxyl-ethyl cellulose were used. The film properties were either varied by the preparation route, i.e., spin coating or drop casting, or via changes in the relative ratio of the ibuprofen and the matrix material. The resulting films were investigated via X-ray diffraction and atomic force microscope experiments. The results show that preferred (100) textures can be induced via spin coating with respect to the glass surface, while the drop casting results in a powder-like behavior. The morphologies of the films are strongly impacted by the ibuprofen amount rather than the preparation method. A comparison of the various matrix materials in terms of their impact on the dissolution properties show a two times faster zero order release from methyl cellulose matrix compared to a polystyrene matrix. The slowest rate was observed within the hydroxyl ethyl cellulose as the active pharmaceutical ingredients (APIs) release is limited by diffusion through a swollen matrix. The investigation reveals that the ibuprofen crystallization and film formation is only little effected by the selected matrix material than that compared to the dissolution. A similar experimental approach using other matrix materials may therefore allow to find an optimized composite layer useful for a defined application. PMID:25275801

2014-01-01

36

Crystallographic textures and morphologies of solution cast Ibuprofen composite films at solid surfaces.  

PubMed

The preparation of thin composite layers has promising advantages in a variety of applications like transdermal, buccal, or sublingual patches. Within this model study the impact of the matrix material on the film forming properties of ibuprofen-matrix composite films is investigated. As matrix materials polystyrene, methyl cellulose, or hydroxyl-ethyl cellulose were used. The film properties were either varied by the preparation route, i.e., spin coating or drop casting, or via changes in the relative ratio of the ibuprofen and the matrix material. The resulting films were investigated via X-ray diffraction and atomic force microscope experiments. The results show that preferred (100) textures can be induced via spin coating with respect to the glass surface, while the drop casting results in a powder-like behavior. The morphologies of the films are strongly impacted by the ibuprofen amount rather than the preparation method. A comparison of the various matrix materials in terms of their impact on the dissolution properties show a two times faster zero order release from methyl cellulose matrix compared to a polystyrene matrix. The slowest rate was observed within the hydroxyl ethyl cellulose as the active pharmaceutical ingredients (APIs) release is limited by diffusion through a swollen matrix. The investigation reveals that the ibuprofen crystallization and film formation is only little effected by the selected matrix material than that compared to the dissolution. A similar experimental approach using other matrix materials may therefore allow to find an optimized composite layer useful for a defined application. PMID:25275801

Kellner, Thomas; Ehmann, Heike M A; Schrank, Simone; Kunert, Birgit; Zimmer, Andreas; Roblegg, Eva; Werzer, Oliver

2014-11-01

37

Cast Fe-base cylinder/regenerator housing alloy  

NASA Technical Reports Server (NTRS)

The development of an iron-base alloy that can meet the requirements of automotive Stirling engine cylinders and regenerator housings is described. Alloy requirements are as follows: a cast alloy, stress for 5000-hr rupture life of 200 MPa (29 ksi) at 775 C (1427 F), oxidation/corrosion resistance comparable to that of N-155, compatibility with hydrogen, and an alloy cost less than or equal to that of 19-9DL. The preliminary screening and evaluation of ten alloys are described.

Larson, F.; Kindlimann, L.

1980-01-01

38

Sensor-Based Assessment of Cast Placement and Removal  

PubMed Central

Appropriate pressure during the application of a cast is critical to provide adequate stabilization of fractures. Force-sensing resistors (FSR) were used to measure pressure during cast placement and removal. The data demonstrated a signature pattern of skin pressure during the different steps of cast placement and removal. This reproducible signal provides validity evidence for our model. PMID:24732518

MAAG, Anne-Lise D.; LAUFER, Shlomi; KWAN, Calvin; COHEN, Elaine R.; LENHART, Rachel L.; STORK, Natalie C.; HALANSKI, Matthew A.; PUGH, Carla M.

2014-01-01

39

A ciliary based 8-legged walking micro robot using cast IPMC actuators  

Microsoft Academic Search

We have proposed a prototype model of walking micro robot using IPMC (Ionic Polymer Metal Composite) actuators. The stiffness of IPMC actuator is a key parameter to implement a walking robot. Therefore, the casting process is developed to increase the stiffness of the actuator by controlling thickness of ion-exchange polymer film. The process of fabricating a solid film front liquid

Byungkyu Kim; Jaewook Ryu; Younkoo Jeong; Younghun Tak; Byungmok Kim; Jong-oh Park

2003-01-01

40

Solvent-cast PCL films support the regeneration of NG108-15 nerve cells  

NASA Astrophysics Data System (ADS)

The reconstruction of peripheral nerve defects over a short distance (10-20mm) could benefit from the development of novel biomaterials. Bio-degradable and bio-compatible materials are being pursued to replace the currently used nerve autografts. We hypothesize that physical properties, particularly surface texture, could have substantial effects on the hydrophilicity of some synthetic polymers and subsequently the compatibility of them with cells. In this study, poly (?-caprolactone) (PCL) films have been cast using four solvents from different chemical families and evaluated for their suitability and potential use as a nerve conduit substratum. The following solvents: dichloromethane (DCM, Halocarbon), methyl acetate (MA, Ester), tetrahydrofuran (THF, Ether) and acetic acid (AA, organic acid) were used to produce PCL films. The physical properties of these PCL films, average surface roughness (Ra) and wettability were measured. Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM) techniques were applied to obtain information on the surface texture. Motor neuron-like NG108-15 cells were used as a model to evaluate the biocompatibility of the films. It was found that same polymer when processed using different solvents could produce materials with markedly different physical and biochemical properties. Importantly, all PCL films were supportive for the growth and differentiation of NG108-15 cells.

Sun, Mingzhu; Downes, Sandra

2007-07-01

41

Improving Drug Loading of Mucosal Solvent Cast Films Using a Combination of Hydrophilic Polymers with Amoxicillin and Paracetamol as Model Drugs  

PubMed Central

Solvent cast mucosal films with improved drug loading have been developed by combining carboxymethyl cellulose (CMC), sodium alginate (SA), and carrageenan (CAR) using paracetamol and amoxicillin as model drugs and glycerol (GLY) as plasticizer. Films were characterized using X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), folding resilience, swelling capacity, mucoadhesivity, and drug dissolution studies. SA, CMC, and GLY (5?:?3?:?6) films showed maximum amoxicillin loading of 26.3% whilst CAR, CMC, and GLY (1?:?2?:?3) films had a maximum paracetamol loading of 40%. XRPD analysis showed different physical forms of the drugs depending on the amount loaded. Films containing 29.4% paracetamol and 26.3% amoxicillin showed molecular dispersion of the drugs while excess paracetamol was observed on the film surface when the maximum 40% was loaded. Work of adhesion was similar for blank films with slightly higher cohesiveness for CAR and CMC based films, but the differences were significant between paracetamol and amoxicillin containing films. The stickiness and cohesiveness for drug loaded films were generally similar with no significant differences. The maximum percentage cumulative drug release was 84.65% and 70.59% for paracetamol and amoxicillin, respectively, with anomalous case two transport mechanism involving both drug diffusion and polymer erosion. PMID:23841056

Kianfar, Farnoosh

2013-01-01

42

Vertical water distribution during the drying of polymer films cast from aqueous emulsions  

NASA Astrophysics Data System (ADS)

We present a systematic study of the vertical uniformity of water distribution during the drying of waterborne colloidal films, testing the predictions of a Peclet number Pe defined for this system. Pe indicates the relative contributions of water evaporation and Brownian diffusion in determining the concentration profile in the vertical direction (i.e. normal to the substrate). When textit{Pe} < 1, the water concentration in films cast from an alkyd emulsion is found via magnetic-resonance profiling to be uniform with depth, which is consistent with expectations. When textit{Pe} > 1, a gradient in the water concentration develops, with less water near the interface with air. The water profiles reveal that the alkyd particles do not coalesce immediately upon contact in close-packing. At later times, a concentrated surface layer develops, but particles are not coalesced in this layer to form a continuous “skin”, but rather the structure is likely to be that of a biliquid foam.

Gorce, J.-P.; Bovey, D.; McDonald, P. J.; Palasz, P.; Taylor, D.; Keddie, J. L.

2002-07-01

43

Vertical water distribution during the drying of polymer films cast from aqueous emulsions.  

PubMed

We present a systematic study of the vertical uniformity of water distribution during the drying of waterborne colloidal films, testing the predictions of a Peclet number Pe defined for this system. Pe indicates the relative contributions of water evaporation and Brownian diffusion in determining the concentration profile in the vertical direction ( i.e. normal to the substrate). When Pe < 1, the water concentration in films cast from an alkyd emulsion is found via magnetic-resonance profiling to be uniform with depth, which is consistent with expectations. When Pe > 1, a gradient in the water concentration develops, with less water near the interface with air. The water profiles reveal that the alkyd particles do not coalesce immediately upon contact in close-packing. At later times, a concentrated surface layer develops, but particles are not coalesced in this layer to form a continuous "skin", but rather the structure is likely to be that of a biliquid foam. PMID:15010943

Gorce, J-P; Bovey, D; McDonald, P J; Palasz, P; Taylor, D; Keddie, J L

2002-07-01

44

A newly developed calcia\\/titanium modified magnesia-based investment mold for titanium casting  

Microsoft Academic Search

Calcia (CaO) investment has the high stability with melted pure titanium (Ti) but the poor manipulation usually leads to low success rate of complete castings. Magnesia (MgO)-based investment can produce the high success rate of pure Ti casting though. However, the MgO-based investment should be accompanied with Ti powder to meet the accuracy of Ti castings. In this study, a

Pei-Ling Lai; Wen-Cheng Chen; Ta-Ko Huang; Chun-Cheng Hung

2011-01-01

45

Natural antimicrobial ingredients incorporated in biodegradable films based on cassava starch  

Microsoft Academic Search

Biodegradable films based on cassava starch and with addition of natural antimicrobial ingredients were prepared using the casting technique. The tensile properties tensile strength (TS) [MPa] and percent elongation (E) at break [%] and the water vapor transmission (WVT) of the biodegradable films were evaluated and compared with the control (without antimicrobial ingredients). The evaluation of the Colony Forming Units

Viviane Kechichian; Cynthia Ditchfield; Pricila Veiga-Santos; Carmen C. Tadini

2010-01-01

46

Coccidioidomycosis among cast and crew members at an outdoor television filming event--California, 2012.  

PubMed

In March 2013, the California Department of Public Health (CDPH) identified two Doctor's First Reports of Occupational Injury or Illness (DFRs) regarding Los Angeles County residents who had worked at the same jobsite in January 2012 and had been evaluated for possible work-associated coccidioidomycosis (valley fever). Occupational exposure to Coccidioides, the causative fungi, typically is associated with soil-disrupting activities. The physicians noted that both workers were cast or crew members filming a television series episode, and the site of possible exposure was an outdoor set in Ventura County, California. On the basis of their job titles, neither would have been expected to have been engaged in soil-disrupting activities. Los Angeles County Department of Public Health (LACDPH) conducted an outbreak investigation by using CDPH-provided occupational surveillance records, traditional infectious disease surveillance, and social media searches. This report describes the results of that investigation, which identified a total of five laboratory-confirmed and five probable cases linked to this filming event. The employer and site manager were interviewed. The site manager stated that they would no longer allow soil-disruptive work at the site and would incorporate information about the potential risk for Coccidioides exposure onsite into work contracts. Public health professionals, clinicians, and the television and film industry should be aware that employees working outdoors in areas where Coccidioides is endemic (e.g., central and southern California), even those not engaged in soil-disruptive work, might be at risk for coccidioidomycosis. PMID:24739339

Wilken, Jason A; Marquez, Patricia; Terashita, Dawn; McNary, Jennifer; Windham, Gayle; Materna, Barbara

2014-04-18

47

Improved mechanical properties of solution-cast silicone film reinforced with electrospun polyurethane nanofiber containing carbon nanotubes  

NASA Astrophysics Data System (ADS)

In this study, we describe the enhancing ability of electrospun polyurethane (PU) nanofibers containing carbon nanotubes (CNTs) as nanofillers for silicone film in improving the physico-mechanical properties of the composite material. We prepared the samples combining two simple techniques: solution casting and electrospinning. Neat PU nanofibers alone are good reinforcing materials but the presence of CNTs inside the PU nanofibers has drastically improved the mechanical properties of the silicone composite film. The silicone film increased its tensile strength by 226% and its tensile modulus by more than 14-fold when CNT/PU nanofibers were incorporated.

Tijing, Leonard D.; Park, Chan-Hee; Kang, Seung-Ji; Amarjargal, Altangerel; Kim, Tae-Hyung; Pant, Hem Raj; Kim, Han Joo; Lee, Dong Hwan; Kim, Cheol Sang

2013-01-01

48

Real-time measurement system for tracking birefringence, weight, thickness, and surface temperature during drying of solution cast coatings and films.  

PubMed

This paper describes the design and performance of a new instrument to track temporal changes in physical parameters during the drying behavior of solutions, as well as curing of monomers. This real-time instrument follows in-plane and out-of-plane birefringence, weight, thickness, and surface temperature during the course of solidification of coatings and films through solvent evaporation and thermal or photocuring in a controlled atmosphere. It is specifically designed to simulate behavior of polymer solutions inside an industrial size, continuous roll-to-roll solution casting line and other coating operations where resins are subjected to ultraviolet (UV) curing from monomer precursors. Controlled processing parameters include air speed, temperature, initial cast thickness, and solute concentration, while measured parameters are thickness, weight, film temperature, in-plane and out-of-plane birefringence. In this paper, we illustrate the utility of this instrument with solution cast and dried poly (amide-imide)?DMAc (Dimethylacetamide) solution, water based black paint, and organo-modified clay?NMP (N-Methylpyrrolidone) solution. In addition, the physical changes that take place during UV photo polymerization of a monomer are tracked. This instrument is designed to be generic and it can be used for tracking any drying?swelling?solidification systems including paper, foodstuffs such as; grains, milk as well as pharmaceutical thin paste and slurries. PMID:22380132

Unsal, E; Drum, J; Yucel, O; Nugay, I I; Yalcin, B; Cakmak, M

2012-02-01

49

Determination of the Lifetime of a Double-Oxide Film in Al Castings  

NASA Astrophysics Data System (ADS)

One of the most important casting defects in Al alloys is thought to be the double-oxide film defect (bifilm) which has been reported to have a deleterious effect on the reproducibility of the mechanical properties of Al castings. Previous research has suggested that the atmosphere inside such bifilms could be consumed by reaction with the surrounding melt, which might decrease the size of the defects and reduce their harmful effect on mechanical properties. In order to follow the change in the composition of the interior atmosphere of a bifilm, analog air bubbles were held inside Al alloy melts, for varying lengths of time, and subjected to stirring, followed by solidification. The bubble contents were then analyzed using a mass spectrometer to determine the changes in their compositions with time. The results suggested that initially oxygen and then nitrogen inside the bubble were consumed, and hydrogen dissolved in the melt diffused into the bubble. The consumption rates of O and N as well as the rate of H diffusion were dependent upon the type of oxide, which was dependent on the alloy composition. The reaction rates were the fastest with MgO (in an Al-5Mg alloy), slower with alumina (in commercial-purity Al alloy), and the slowest with MgAl2O4 spinel (in an Al-7Si-0.3Mg alloy). It was estimated that the times required for typical bifilm defects in the different alloys to lose their entire oxygen and nitrogen contents were about 345 seconds (~6 minutes), in the case of Al-5Mg; 538 seconds (~9 minutes), in the case of a commercial purity alloy; and 1509 seconds (~25 minutes), in the case of the Al-7Si-0.3Mg alloy (2L99) due to the different oxides that the different alloys would be expected to form.

El-Sayed, Mahmoud Ahmed; Salem, Hanadi A. G.; Kandeil, Abdelrazek Youssef; Griffiths, W. D.

2014-08-01

50

Hardware-Based Ray Casting for Tetrahedral Meshes  

Microsoft Academic Search

We present the first implementation of a volume ray casting algorithm for tetrahedral meshes running on off-the-shelf programmable graphics hardware. Our implementation avoids the memory transfer bottleneck of the graphics bus since the complete mesh data is stored in the local memory of the graphics adapter and all computations, in particular ray traversal and ray integration, are performed by the

Manfred Weiler; Martin Kraus; Markus Merz; Thomas Ertl

2003-01-01

51

Electrical transport and grain growth in solution-cast, chloride-terminated cadmium selenide nanocrystal thin films.  

PubMed

We report the evolution of electrical transport and grain size during the sintering of thin films spin-cast from soluble phosphine and amine-bound, chloride-terminated cadmium selenide nanocrystals. Sintering of the nanocrystals occurs in three distinct stages as the annealing temperature is increased: (1) reversible desorption of the organic ligands (?150 °C), (2) irreversible particle fusion (200-300 °C), and (3) ripening of the grains to >5 nm domains (>200 °C). Grain growth occurs at 200 °C in films with 8 atom % Cl(-), while films with 3 atom % Cl(-) resist growth until 300 °C. Fused nanocrystalline thin films (grain size = 4.5-5.5 nm) on thermally grown silicon dioxide gate dielectrics produce field-effect transistors with electron mobilities as high as 25 cm(2)/(Vs) and on/off ratios of 10(5) with less than 0.5 V hysteresis in threshold voltage without the addition of indium. PMID:24960255

Norman, Zachariah M; Anderson, Nicholas C; Owen, Jonathan S

2014-07-22

52

Conical surface structures on model thin-film electrodes and tape-cast electrode materials for lithium-ion batteries  

NASA Astrophysics Data System (ADS)

Three-dimensional structures in cathode materials for lithium-ion batteries were investigated in this study. For this purpose, laser structuring of lithium cobalt oxide was investigated at first for a thin-film model system and in a second step for conventional tape-cast electrode materials. The model thin-film cathodes with a thickness of 3 ?m were deposited using RF magnetron sputtering on stainless steel substrates. The films were structured via excimer laser radiation with a wavelength of 248 nm. By adjusting the laser fluence, self-organized conical microstructures were formed. Using conventional electrodes, tape-cast cathodes made of LiCoO2 with a film thickness of about 80 ?m on aluminum substrates were studied. It was shown that self-organizing surface structures could be formed by adjustment of the laser parameters. To investigate the formation mechanisms of the conical topography, the element composition was studied by time-of-flight secondary ion mass spectrometry and X-ray photoelectron spectroscopy. Electrochemical cycling using a lithium anode and conventional electrolyte was applied to study the influence of the laser processing procedures on cell performance. For the model electrode system, a significantly higher discharge capacity of 80 mAh/g could be obtained after 110 cycles by laser structuring compared to 8 mAh/g of the unstructured thin film. On conventional tape-cast electrodes self-organized surface structures could also increase the cycling stability resulting in an 80 % increase in capacity after 110 cycles in comparison to the unstructured electrode.

Kohler, R.; Proell, J.; Bruns, M.; Ulrich, S.; Seifert, H. J.; Pfleging, W.

2013-07-01

53

Caste-, work-, and descent-based discrimination as a determinant of health in social epidemiology.  

PubMed

Social epidemiology explores health in the context of broad social determinants of health, where the boundary lines between health and politics appear increasingly blurred. Social determinants of health such as caste, discrimination, and social exclusion are inherently political in nature, hence it becomes imperative to look at health through a broader perspective of political philosophy, ideology, and caste that imposes enormous obstacles to a person's full attainment of civil, political, economic, social, and cultural rights. Caste is descent based and hereditary in nature. It is a characteristic determined by one's birth into a particular caste, irrespective of the faith practiced by the individual. Caste denotes a system of rigid social stratification into ranked groups defined by descent and occupation. Under various caste systems throughout the world, caste divisions also dominate in housing, marriage, and general social interaction divisions that are reinforced through the practice and threat of social ostracism, economic boycotts, and even physical violence-all of which undermine health equality. PMID:24871772

Patil, Rajan R

2014-01-01

54

Physicochemical properties of the amorphous drug, cast films, and spray dried powders to predict formulation probability of success for solid dispersions: etravirine.  

PubMed

Solid dispersion technology represents an enabling approach to formulate poorly water-soluble drugs. While providing for a potentially increased oral bioavailability secondary to an increased drug dissolution rate, amorphous dispersions can be limited by their physical stability. The ability to assess formulation risk in this regard early in development programs can not only help in guiding development strategies but can also point to critical design elements in the configuration of the dosage form. Based on experience with a recently approved solid dispersion-based product, Intelence® (etravirine), a three part strategy is suggested to predict early formulate-ability of these systems. The components include an assessment of the amorphous form, a study of binary drug/carrier cast films and the evaluation of a powder of the drug and polymer processed in a manner relevant to the intended final dosage form. A variety of thermoanalytical, spectroscopic, and spectrophotometric approaches were applied to study the prepared materials. The data suggest a correlation between the glass forming ability and stability of the amorphous drug and the nature of the final formulation. Cast films can provide early information on miscibility and stabilization and assessment of processed powders can help define requirements and identify issues with potential final formulations. PMID:20575005

Weuts, Ilse; Van Dycke, Frederic; Voorspoels, Jody; De Cort, Steve; Stokbroekx, Sigrid; Leemans, Ruud; Brewster, Marcus E; Xu, Dawei; Segmuller, Brigitte; Turner, Ya Tsz A; Roberts, Clive J; Davies, Martyn C; Qi, Sheng; Craig, Duncan Q M; Reading, Mike

2011-01-01

55

A ciliary motion based 8-legged walking micro robot using cast IPMC actuators  

Microsoft Academic Search

In this paper, we present a micro robot using IPMC (Ionic Polymer Metal Composite) actuators. The IPMC actuator usually has been fabricated with commercially available ion-exchange polymer with the typical thickness of 100-300 ?m. By the casting of liquid ion-exchange polymer solution, the thickness of the IPMC actuator could increase up to a few millimeters. Based on the casting method,

Jaewook Ryu; Younkoo Jeong; Younghun Tak; Byungmok Kim; Byungkyu Kim; Jong-Oh Parkb

2002-01-01

56

Oxide defects in a vacuum investment-cast ni-based turbine blade  

Microsoft Academic Search

Samples from large turbine blades for power generation, investment-cast in vacuum from a nickel-based superalloy, were investigated.\\u000a Samples were cut from regions near the top of the casting that contained freckle defects. The microstructures of these segregated\\u000a regions were compared with those from nonsegregated adjacent regions using both optical microscopy and scanning electron microscopy\\u000a (SEM). The segregated areas revealed a

A. K. M. B. Rashid; J. Campbell

2004-01-01

57

Die Casting.  

National Technical Information Service (NTIS)

Contents: Mechanical properties of creep resistant zinc die casting alloys; Studies on a gravity die cast zinc base alloy; Parashot system for turbulence-free injection of metal; Zinc--the versatile metal; Prevention of metal dribble on hot chamber die ca...

1977-01-01

58

Solution-cast metal oxide thin film electrocatalysts for oxygen evolution.  

PubMed

Water oxidation is a critical step in water splitting to make hydrogen fuel. We report the solution synthesis, structural/compositional characterization, and oxygen evolution reaction (OER) electrocatalytic properties of ~2-3 nm thick films of NiO(x), CoO(x), Ni(y)Co(1-y)O(x), Ni(0.9)Fe(0.1)O(x), IrO(x), MnO(x), and FeO(x). The thin-film geometry enables the use of quartz crystal microgravimetry, voltammetry, and steady-state Tafel measurements to study the electrocatalytic activity and electrochemical properties of the oxides. Ni(0.9)Fe(0.1)O(x) was found to be the most active water oxidation catalyst in basic media, passing 10 mA cm(-2) at an overpotential of 336 mV with a Tafel slope of 30 mV dec(-1) with oxygen evolution reaction (OER) activity roughly an order of magnitude higher than IrO(x) control films and similar to the best known OER catalysts in basic media. The high activity is attributed to the in situ formation of layered Ni(0.9)Fe(0.1)OOH oxyhydroxide species with nearly every Ni atom electrochemically active. In contrast to previous reports that showed synergy between Co and Ni oxides for OER catalysis, Ni(y)Co(1-y)O(x) thin films showed decreasing activity relative to the pure NiO(x) films with increasing Co content. This finding is explained by the suppressed in situ formation of the active layered oxyhydroxide with increasing Co. The high OER activity and simple synthesis make these Ni-based catalyst thin films useful for incorporating with semiconductor photoelectrodes for direct solar-driven water splitting or in high-surface-area electrodes for water electrolysis. PMID:22991896

Trotochaud, Lena; Ranney, James K; Williams, Kerisha N; Boettcher, Shannon W

2012-10-17

59

GRAIN REFINEMENT OF PERMANENT MOLD CAST COPPER BASE ALLOYS  

SciTech Connect

Grain refinement behavior of copper alloys cast in permanent molds was investigated. This is one of the least studied subjects in copper alloy castings. Grain refinement is not widely practiced for leaded copper alloys cast in sand molds. Aluminum bronzes and high strength yellow brasses, cast in sand and permanent molds, were usually fine grained due to the presence of more than 2% iron. Grain refinement of the most common permanent mold casting alloys, leaded yellow brass and its lead-free replacement EnviroBrass III, is not universally accepted due to the perceived problem of hard spots in finished castings and for the same reason these alloys contain very low amounts of iron. The yellow brasses and Cu-Si alloys are gaining popularity in North America due to their low lead content and amenability for permanent mold casting. These alloys are prone to hot tearing in permanent mold casting. Grain refinement is one of the solutions for reducing this problem. However, to use this technique it is necessary to understand the mechanism of grain refinement and other issues involved in the process. The following issues were studied during this three year project funded by the US Department of Energy and the copper casting industry: (1) Effect of alloying additions on the grain size of Cu-Zn alloys and their interaction with grain refiners; (2) Effect of two grain refining elements, boron and zirconium, on the grain size of four copper alloys, yellow brass, EnviroBrass II, silicon brass and silicon bronze and the duration of their effect (fading); (3) Prediction of grain refinement using cooling curve analysis and use of this method as an on-line quality control tool; (4) Hard spot formation in yellow brass and EnviroBrass due to grain refinement; (5) Corrosion resistance of the grain refined alloys; (6) Transfer the technology to permanent mold casting foundries; It was found that alloying elements such as tin and zinc do not change the grain size of Cu-Zn alloys. Aluminum promoted b phase formation and modified the grain structure from dendritic to equiaxed. Lead or bismuth reduces the size of grains, but not change the morphology of the structure in Cu-Zn alloys. The grain size of the Cu-Zn-alloy can be reduced from 3000 mm to 300 mm after the addition of aluminum and lead. Similar effects were observed in EnviroBrass III after the addition of aluminum and bismuth. Boron refined the structure of yellow brasses in the presence of iron. At least 50 ppm of iron and 3 ppm of boron are necessary to cause grain refinement in these alloys. Precipitation of iron from the melt is identified as the cause of grain refinement. Boron initiates the precipitation of iron which could not be explained at this time. On the other hand zirconium causes some reduction in grain size in all four alloys investigated. The critical limit for the zirconium was found to be around 100 ppm below which not much refinement could be observed. The mechanism of grain refinement in the presence of zirconium could not be explained. Grain refinement by boron and iron can remain over a long period of time, at least for 72 hours of holding or after remelting few times. It is necessary to have the iron and boron contents above the critical limits mentioned earlier. On the other hand, refinement by zirconium is lost quite rapidly, some times within one hour of holding, mostly due to the loss of zirconium, most probably by oxidation, from the melt. In all the cases it is possible to revive the refinement by adding more of the appropriate refining element. Cooling curve analysis (thermal analysis) can be used successfully to predict the grain refinement in yellow brasses. The precipitation of iron in the liquid metal causes the metal to solidify without undercooling. Absence of this reaction, as indicated by the time-temperature (t-T) and its first derivative (dt/dT) curves, proved to be an indicator of refinement. The viability of the technique as an on-line quality control tool was proved in two foundries. The method can also correctly predict the onset of fading. Th

M. SADAYAPPAN, J.P. THOMSON, M.ELBOUJDAINI, G. PING GU, M. SAHOO

2004-04-29

60

As-cast magnets based on Fe-Nd-C  

NASA Astrophysics Data System (ADS)

Fe14Nd2C (?) shows structural and intrinsic magnetic properties comparable to Fe14Nd2B. The phase Fe14Nd2C is found in long-time-annealed samples only (?20 d at 850 °C) because of nucleation difficulties and slow growth kinetics. Compared to the Fe-Nd-B system the phase relations in the Fe-Nd-C system are unfavorable to produce sintered or even as-cast magnet materials, as manifested in the phase diagram presented. Fe14Nd2C is in equilibrium with either ferromagnetic and/or very corrosive phases, therefore the pure Fe-Nd-C material is useless. This situation can be changed by the addition of several elements to the Fe-Nd-C material: boron (even in small amounts of ?0.05 mass %) accelerates the formation of ? and reduces annealing times from weeks to hours; Cu added in the correct amount leads to new phase relations between ? and NdxCuy intermetallic compounds. These intermetallics are nonmagnetic and low melting. Starting from as-cast material using the knowledge about the influences of substituants on phase relations and kinetics, a heat treatment can be chosen that leads directly to an isotropic, magnetically hard material with a rather small grain size (?20 ?m) and coercivities up to 1 T. The magnetization is comparable to isotropic Fe-Nd-B materials.

Grieb, B.; Fritz, K.; Henig, E.-Th.

1991-11-01

61

Urinary casts  

MedlinePLUS

... casts; Casts in the urine; Fatty casts; Red blood cell casts; White blood cell casts ... dehydration, exercise, or (water pills) diuretic medicines. Red blood cell casts are a sign of bleeding into ...

62

SIMULATION OF NI3AL-BASED ALLOY AND INVESTMENT CASTING PROCESS OF ITS THIN WALL PARTS  

Microsoft Academic Search

The castability is poor to produce thin wall complex castings of the Ni3Al-based alloy by investment casting. In general, such as incomplete mold filling and hot tears defects appear commonly. In this paper, physical parameters of Ni3Al- based alloy are obtained by experiments and simulations using JmatPro software, and casting process of thin wall parts is optimized by the simulation

Zhang Xi-e; Cao Xu; Luo He-li; Feng Di; Li Shang-ping

63

Morphological, Mechanical and Thermal Study of ZnO Nanoparticle Reinforced Chitosan Based Transparent Biocomposite Films  

NASA Astrophysics Data System (ADS)

Chitosan based biocomposite transparent films reinforced with zinc oxide (ZnO) nanoparticles at different loading i.e. 2, 4 and 6 wt% were successfully prepared by solution casting method. Shape, size and geometry of the zinc oxide nanoparticles were characterized by scanning electron microscopy (SEM). The biocomposite films were subjected to mechanical characterization, thermal analysis, morphology study and moisture uptake behaviour. The characterization tools used here include wide angle X-ray diffraction study, scanning electron microscopic analysis, differential scanning calorimetric analysis and also UV-visible transmittance behavior. SEM micrographs revealed uniformly dispersed ZnO nanoparticles in biocomposite films. Improvement of the tensile strength about 133 % was observed significantly in case of 4 wt% loaded chitosan/ZnO films with respect to the neat chitosan film. 43 % higher transparency was observed in case of 2 wt% ZnO loaded biocomposites films, thus indicating the best combination of properties of 2 wt% ZnO loaded biocomposite films.

Das, Kunal; Maiti, Sonakshi; Liu, Dagang

2014-04-01

64

Casting Technology.  

ERIC Educational Resources Information Center

Three articles discuss (1) casting technology as it relates to industry, with comparisons of shell casting, shell molding, and die casting; (2) evaporative pattern casting for metals; and (3) high technological casting with silicone rubber. (JOW)

Wright, Michael D.; And Others

1992-01-01

65

Influence of Phenolic Compounds in the Combustion of Cast Double Base Propellants Containing Lead Stearate  

Microsoft Academic Search

The effect of different cresols (o, m, p), resorcinol and pyrogallol in the presence and absence of lead stearate on the burning rates of cast double base propellants has been studied in the 35?140 kg\\/cm pressure range. While their effect is not significant without lead stearate, these phenolic compounds increased burning rates in the presence of lead stearate. Their mode

HARIDWAR SINGH; K. V. RAMAN; K. R. K. RAO

1980-01-01

66

Breakout Prediction Based on BP Neural Network of LM Algorithm in Continuous Casting Process  

Microsoft Academic Search

An improved BP neural network model was presented by modifying the learning algorithm of the traditional BP neural network, based on the Levenberg-Marquardt algorithm, and was applied to the breakout prediction system in the continuous casting process. The results showed that the accuracy rate of the model for the temperature pattern of sticking breakout was 96.43%, and the quote rate

Ben-guo Zhang; Qiang Li; Ge Wang; Ying Gao

2010-01-01

67

Utility and Stability Measures for Agent-Based Dynamic Scheduling of Steel Continuous Casting  

Microsoft Academic Search

This paper describes a new model for robust predictive\\/reactive scheduling of steel continuous casting based on the use of multi-agents, tabu search and heuristic approaches. A continuous caster agent generates a predictive production schedule taking into account manufacturing requirements and local constraints using tabu search. The predictive schedule is modified so as to minimise deviation between the performance measure values

D. Quelhadj; Peter I. Cowling; Sanja Petrovic

2003-01-01

68

Reversible Photoinduced Switching of Permeability in a Cast Non-Porous Film Comprising Azobenzene Liquid Crystalline Polymer.  

PubMed

Permeation characteristics of an azobenzene-containing liquid crystalline (LC) non-porous film are investigated using a metallic corrosion method. Thin films (300?nm) are fabricated by the solution casting of an azobenzene side-chain LC polymer on freshly polished carbon steel coupons. Coated coupons are treated under the following conditions: a) gradual annealing at a cooling rate lower than 1?°C?·?min(-1) from 150?°C (above its T(g) ) to room temperature, and b) irradiation at 465?nm (20 mW?·?cm(-2) ) with either circularly polarized light (CPL) or non-polarized light (NPL). The morphology of these films is characterized using X-ray diffraction, polarized optical microscopy, and transmission measurements. The results suggest that the annealing treatment resulted in the formation of a polydomain structure consisting of locally ordered small smectic domains that lack mutual orientation. Ordered micro domains are surrounded by disordered phases. CPL and NPL irradiation generates a monodomain orientated structure and an isotropic liquid crystal glass, respectively. The permeability of these non-porous films treated by CPL, NPL, and annealing are found to be 6.14?×?10(-4) , 1.92?×?10(-2) , and 1.56?×?10(-3) cm(3) ?·?m(-2) ?·?d(-1) . An orientation-dependent structure model is constructed to explain the permeation phenomenon, considering the ordered phase is impermeable, only the disordered phase is accessible to penetrating molecules. Fast switching of gas permeation is demonstrated by alternative irradiation of the film with CPL and NPL, which results in an approximately 30-fold difference in the permeability of the non-porous film. PMID:21786360

Liu, Jian; Wang, Mingle; Dong, Mingling; Gao, Liude; Tian, Jingjing

2011-07-22

69

Fabrication of Meso-Porous Gamma-Alumina Films by Sol-Gel and Gel Casting Processes for Making Moisture Sensors  

Microsoft Academic Search

Meso-porous ?-Al2O3 film may be used as a highly sensitive trace moisture sensor. The crack-free alumina film was developed using a combination of sol-gel and tape casting processes, which produce high porosity, high surface area and small pore dimensions in the range of few nano- meter at uniform distribution. Sol-gel processes are well known in nano-technology and nano-material preparation, but

Kalyan Kumar Mistry

70

Corrosion mechanisms of low porosity ZrO 2 based materials during near net shape steel casting  

Microsoft Academic Search

One of the most promising refractory materials for application in near net shape steel casting technologies is zirconia. The corrosion resistance of zirconia based materials in contact with steel and aggressive high casting speed powders has been investigated in a specially designed device simulating operating conditions; the corrosion mechanisms have been illustrated.

C. G Aneziris; E. M Pfaff; H. R Maier

2000-01-01

71

Online Measurement for Transient Mold Friction Based on the Hydraulic Oscillators of Continuous-Casting Mold  

NASA Astrophysics Data System (ADS)

The interaction of the strand shell surface and mold copper plates has significant effects on the slab surface quality and casting productivity. This article focuses on developing a reliable approach to measure the transient friction force between the slab and the mold for the purpose of the investigation of lubrication and friction behavior inside a mold. This method is presented to monitor transient mold frictions for the slab continuous caster equipped with hydraulic oscillators. A mathematical model is also developed to calculate the empty working force of the no casting state, and a new algorithm, based on the particle swarm optimization, is proposed to predict the dynamic characteristic parameters of mold oscillation. The results have shown that the method has a sufficient sensitivity to variation, especially to the periodical variation of the mold friction, and it has been identified that the transient mold friction can be used as an effective index with regard to detecting mold oscillation and optimizing the casting parameters for process control. It may lay the practical foundation for the online detection of powder lubrication and the visualization of the continuous-casting mold process.

Wang, Xudong; Wang, Zhaofeng; Yao, Man

2013-12-01

72

Film Analysis through Linguistic Base  

ERIC Educational Resources Information Center

Studies made in the last few years show that using films in language classrooms is an effective way in teaching a foreign language. Well-chosen films can serve as a valuable pedagogical aid, both for classroom use and self-study. This article is about using films in language classrooms through a specially designed course, whose outline description…

Tanriverdi, Belgin

2007-01-01

73

Microwave transmittance in gelatin-based films  

NASA Astrophysics Data System (ADS)

Biopolymers are alternative materials used in the production of edible and/or biodegradable films. A very important restriction factor concerning the films is their sensitivity to environmental conditions, such as temperature and relative humidity. The production of films based on gelatin and polyvinyl alcohol blends can be an alternative solution in order to reduce the sensitivity to the humidity. Thus, the aim of this work was to apply the microwave transmittance technique to measure qualitative effects of the presence of glycerol and polyvinyl alcohol on the moisture content of gelatin-based films. The results show that the films with glycerol, conditioned for one week in NaBr, revealed visible changes between 11 and 13 GHz as the plasticizer concentration increased. For gelatin films containing PVA, the results revealed very low microwave insertion losses. Thus, this behaviour was attributed to the presence of water molecules in gelatin films.

Bergo, P.; Carvalho, R. A.; Sobral, P. J. A.; Bevilacqua, F. R. S.; Pinto, J. K. C.; Souza, J. P.

2006-12-01

74

Technology and experiments of 42CrMo bearing ring forming based on casting ring blank  

NASA Astrophysics Data System (ADS)

Bearing ring is the crucial component of bearing. With regard to such problems as material waste, low efficiency and high energy consumption in current process of producing large bearing ring, a new process named "casting-rolling compound forming technology" is researched by taking the typical 42CrMo slew bearing as object. Through theoretical analysis, the design criteria of the main casting-rolling forming parameters are put forward at first. Then the constitutive relationship model of as-cast 42CrMo steel and its mathematical model of dynamic recrystallization are obtained according to the results of the hot compression experiment. By a coupled thermal-mechanical finite element model for radial-axial rolling of bearing ring, the fraction of dynamic recrystallization is calculated and recrystallized grains size are predicated. Meanwhile, the effects of the initial rolling temperature and feed rate of idle roll on material microstructure evolution are analyzed. Finally, the industrial rolling experiment is designed and performed, based on the simulation results. In addition, mechanical and metallographic tests are conducted on rolled bearing ring to get the mechanical parameters and metallographic structure. The experimental data and results show that the mechanical properties of bearing ring produced by casting-rolling compound forming technology are up to industrial standard, and a qualified bearing ring can be successfully formed by employing this new technology. Through the study, a process of forming large bearing ring directly by using casting ring blank is obtained, which could provide an effective theoretical guidance for manufacturing large ring parts. It also has an edge in saving material, lowering energy and improving efficiency.

Li, Yongtang; Ju, Li; Qi, Huiping; Zhang, Feng; Chen, Guozhen; Wang, Mingli

2014-03-01

75

High-Quality Hardware-Based Ray-Casting Volume Rendering Using Partial Pre-Integration  

Microsoft Academic Search

In this paper, we address the problem of the interac- tive volume rendering of unstructured meshes and propose a new hardware-based ray-casting algorithm using partial pre-integration. The proposed algorithm makes use of mod- ern programmable graphics card and achieves rendering rates competitive with full pre-integration approaches (up to 2M tet\\/sec). This algorithm allows the interactive mod- ication of the transfer

Rodrigo Espinha; Waldemar Celes Filho

2005-01-01

76

Evaluation of solid-liquid interface profile during continuous casting by a spline based formalism  

Microsoft Academic Search

A numerical framework has been applied which comprises of a cubic spline based collocation method to determine the solid-liquid\\u000a interface profile (solidification front) during continuous casting process. The basis function chosen for the collocation\\u000a algorithm to be employed in this formalism, is a cubic spline interpolation function. An iterative solution methodology has\\u000a been developed to track the interface profile for

S. K. Das

2001-01-01

77

Fabrication of a zirconia MEMS-based microthruster by gel casting on PDMS soft molds  

Microsoft Academic Search

A zirconia microelectromechanical-system-based microthruster was fabricated through a newly developed fabrication route. Gel casting of homogenously dispersed zirconia suspension on polydimethylsiloxane soft mold was utilized to replicate the geometries of microthruster design onto a ceramic layer of about 1.2 mm thick. Lamination of the patterned ceramic layer to another flat ceramic layer and subsequent sintering produced the microthruster. Characterizations on

K H Cheah; P S Khiew; J K Chin

2012-01-01

78

A facile and simple high-performance polydimethylsiloxane casting based on self-polymerization dopamine  

NASA Astrophysics Data System (ADS)

We present a new and facile method for polydimethylsiloxane (PDMS) casting by dip-coating the master molds in an aqueous solution of dopamine. A poly(dopamine) film formed by self-polymerization of dopamine is used as the surface anti-adhesion coating for PDMS de-molding. Different master molds, such as metal, silicon and PDMS replica, were used to verify the feasibility of this proposed PDMS casting method. The poly(dopamine) coatings at various fabrication conditions were studied by using surface plasmon resonance technology. We found that it is very easy to form repeated poly(dopamine) coatings with similar thicknesses and density at fairly flexible conditions of self-polymerization. The water contact angles of the PDMS master molds and the positive PDMS replicas were studied after the PDMS master molds were immersed in the dopamine coating solution for different times. The de-molding process was then measured by surface plasmon resonance technology. The surface morphology of the master molds and the PDMS replicas were characterized by using scanning electron microscopy and atomic force microscopy. Results demonstrate that the poly(dopamine) coating exhibits a strong release property in the PDMS de-molding process and has good stickiness after PDMS de-molding a dozen times. The package performances of the PDMS replicas were detected and compared by bonding experiments. PDMS replicas after a second round of de-molding present a little higher package performance than that of the PDMS replicas with an anti-sticking agent of silane. The biochemical properties of PDMS replicas were studied through fluorescence immunoassay experiments. The PDMS replicas present similar biochemical properties to the bare PDMS. This biomimetic surface modification method of dopamine for PDMS casting has a great potential for preparing microdevices for various biological and clinical applications.

Chen, Xing; Zhang, Lu-lu; Sun, Jian-hai; Li, Hui; Cui, Da-fu

2014-09-01

79

Pattern formation in soft elastic films cast on periodically corrugated surfaces—a linear stability and finite element analysis  

NASA Astrophysics Data System (ADS)

Length scales of instabilities exhibited by soft, thin elastic films cast on smooth and sharp corrugated surfaces and in adhesive contact with an external contactor are investigated by means of linear stability analysis (LSA) and non-linear finite element analysis. The instability length scales are found to decrease with either an increase in the amplitude ? or a decrease in the wavelength ?p of the substrate pattern. For same substrate parameters, a step-patterned surface with higher RMS roughness is generally found to engender smaller length scales. The linear stability analysis with sinusoidally patterned substrates shows a reduced scaling of critical wavelength with substrate amplitude: ?c = 2.96(1 - ?)h, where h is the mean film thickness. The largest substrate amplitudes explored with finite element analysis are limited to ? = 0.7, which is found to beget instability length scales of 0.89h, that are much smaller than the 3h length scale that is obtained with flat substrates. This suggests that an increase in substrate roughness via patterning can prove to be an attractive route for the production of miniaturized patterns.

Annepu, Hemalatha; Sarkar, Jayati; Basu, Sumit

2014-07-01

80

Mechanical and thermal properties of irradiated films based on Tilapia ( Oreochromis niloticus) proteins  

NASA Astrophysics Data System (ADS)

Proteins are considered potential material in natural films as alternative to traditional packaging. When gamma radiation is applied to protein film forming solution it resulted in an improvement in mechanical properties of whey protein films. The objective of this work was the characterization of mechanical and thermal properties of irradiated films based on muscle proteins from Nile Tilapia ( Oreochromis niloticus). The films were prepared according to a casting technique with two levels of plasticizer: 25% and 45% glycerol and irradiated in electron accelerator type Radiation Dynamics, 0.550 MeV at dose range from 0 to 200 kGy. Thermal properties and mechanical properties were determined using a differential scanning calorimeter and a texture analyzer, respectively. Radiation from electron beam caused a slightly increase on its tensile strength characteristic at 100 kGy, while elongation value at this dose had no reduction.

Sabato, S. F.; Nakamurakare, N.; Sobral, P. J. A.

2007-11-01

81

Classification of cast iron based on graphite grain morphology using neural network approach  

NASA Astrophysics Data System (ADS)

The ISO-9452 committee has defined six classes of grain morphology through reference drawings for cast iron graphite grain classification. These reference drawings are universally accepted for classification of graphite grains. The main aim of this work is to propose a neural network approach for cast iron classification based on graphite grain morphology by processing microstructure images. The two sets of shape features investigated are, Simple Shape Descriptors (SSDs) and Moment Invariants(MIs). The classifiers like, feed forward neural network with back propagation and radial basis functions are also investigated. The experimentation is carried out using the metallographic images from the well known microstructures library4. For training and testing the networks, the grain shapes identified in ISO-945 reference drawings and the grain classification by the experts are used. The moment invariant shape features and neural network classifier with radial basis function yield better classification results for graphite grains.

Pattan, Prakash C.; Mytri, V. D.; Hiremath, P. S.

2010-02-01

82

LineCast: line-based distributed coding and transmission for broadcasting satellite images.  

PubMed

In this paper, we propose a novel coding and transmission scheme, called LineCast, for broadcasting satellite images to a large number of receivers. The proposed LineCast matches perfectly with the line scanning cameras that are widely adopted in orbit satellites to capture high-resolution images. On the sender side, each captured line is immediately compressed by a transform-domain scalar modulo quantization. Without syndrome coding, the transmission power is directly allocated to quantized coefficients by scaling the coefficients according to their distributions. Finally, the scaled coefficients are transmitted over a dense constellation. This line-based distributed scheme features low delay, low memory cost, and low complexity. On the receiver side, our proposed line-based prediction is used to generate side information from previously decoded lines, which fully utilizes the correlation among lines. The quantized coefficients are decoded by the linear least square estimator from the received data. The image line is then reconstructed by the scalar modulo dequantization using the generated side information. Since there is neither syndrome coding nor channel coding, the proposed LineCast can make a large number of receivers reach the qualities matching their channel conditions. Our theoretical analysis shows that the proposed LineCast can achieve Shannon's optimum performance by using a high-dimensional modulo-lattice quantization. Experiments on satellite images demonstrate that it achieves up to 1.9-dB gain over the state-of-the-art 2D broadcasting scheme and a gain of more than 5 dB over JPEG 2000 with forward error correction. PMID:24474371

Wu, Feng; Peng, Xiulian; Xu, Jizheng

2014-03-01

83

Dielectric behaviour of emeraldine base polymer–ZnO nanocomposite film in the low to medium frequency  

Microsoft Academic Search

Emeraldine base (EB) polymer–ZnO nanoparticles composite films has been synthesized by solution casting technique on ITO-coated\\u000a glass substrate and characterized by XRD, FTIR and TEM for their structure and morphology. Dielectric behaviour of these composite\\u000a films has been investigated in the very low frequency region to medium frequency region (1 kHz–1 MHz). The dielectric constant\\u000a of the composite with 30% nanoparticles is

M. L. Singla; Rajeev Sehrawat; Nidhi Rana; Kulvir Singh

2011-01-01

84

Project CAST.  

ERIC Educational Resources Information Center

The document outlines procedures for implementing Project CAST (Community and School Together), a community-based career education program for secondary special education students in Charles County, Maryland. Initial sections discuss the role of a learning coordinator, (including relevant travel reimbursement and mileage forms) and an overview of…

Charles County Board of Education, La Plata, MD. Office of Special Education.

85

Modeling and analysis of film composition on mechanical properties of maize starch based edible films.  

PubMed

The present study investigates the influence of composition (content of maize starch (1-3 g), sorbitol (0.5-1.0 ml), agar (0.5-1.0 g) and tween-80 (0.1-0.5 ml)) on the mechanical properties (tensile strength, elongation, Young's modulus, puncture force and puncture deformation) of the maize starch based edible films using four factors with three level Box-Behnken design. The edible films were obtained by casting method. The results showed that, tween-80 increases the permeation of sorbitol in to the polymer matrix. Increasing concentration of sorbitol (hydrophilic nature and plasticizing effect of sorbitol) decreases the tensile strength, Young's modulus and puncture force of the films. The results were analyzed by Pareto analysis of variance (ANOVA) and second order polynomial models were obtained for all responses with high R(2) values (R(2)>0.95). 3D response surface plots were constructed to study the relationship between process variables and the responses. PMID:24080451

Prakash Maran, J; Sivakumar, V; Thirugnanasambandham, K; Kandasamy, S

2013-11-01

86

Corrosion behavior of cast and forged cobalt-based alloys for double-alloy joint endoprostheses.  

PubMed

An ideal combination of mechanical and corrosion properties of long-term implants such as joint endoprostheses has yet to be found. Besides being resistant to pitting and crevice attack, which can lead to corrosion fatigue and stress corrosion cracking failures, the implant material must be highly resistant to wear and abrasion. Two cobalt-based alloys, wrought CoNiMoTi and air-cast CoCrMo, were subjected to a number of selected in vitro electrochemically and chemically accelerated corrosion tests in chloride-containing solutions with wrought AISI-316L used as a reference alloy. A limited number of immersion tests in FeCl3 and acidified FeCl3 solutions were also conducted. It is found that the mechanical properties of wrought CoNiCrMoTi alloy qualify it as a substitute for cast CoCrMo alloy and wrought AISI-316L in anchorage shaft production for all types of joint endoprostheses. Wrought CoNiCrMoTi has a higher resistance to fatigue cracking compared with cast CoCrMo and is as resistant to selective corrosion phenomena such as stress corrosion cracking. PMID:701305

Süry, P; Semlitsch, M

1978-09-01

87

An intelligent knowledge based approach for the automated radiographic inspection of castings  

NASA Astrophysics Data System (ADS)

An automated system for the radiographic inspection of castings is described which is based on both conventional image processing techniques and intelligent knowledge based techniques for the identification and evaluation of defects against quality assurance standards. An evaluation of the performance of the system against that of skilled inspectors demonstrates that the system is capable of meeting the requirements for an automated system for industrial radiographic inspection. The overall design of the system and elements of the system, including the knowledge representation scheme, inference mechanism, and control structure, are described. The discussion also covers examples of frame structures, frame taxonomies, data driven maintenance procedures, and rules for classification and evaluation.

Kehoe, A.; Parker, G. A.

88

The caste based mosaic of Indian politics C H R I S T O P H E J A F FR E L O T  

E-print Network

The caste based mosaic of Indian politics C H R I S T O P H E J A F FR E L O T WHILE caste politics voters, are associated with a single caste and/or religious community � and this is also true of some that this redrawing of the frontiers of the state in large part stemmed from the demands of dominant castes. In 1947

Boyer, Edmond

89

Novel composite films based on amidated pectin for cationic dye adsorption.  

PubMed

Pectin, with its tendency to gel in the presence of metal ions has become a widely used material for capturing the metal ions from wastewaters. Its dye-capturing properties have been much less investigated, and this paper is the first to show how films based on amidated pectin can be used for cationic dye adsorption. In the present study amidated pectin/montmorillonite composite films were synthesized by membrane casting, and they are stable in aqueous solution both below and above pectin pKa. FTIR, thermogravimetry and SEM-EDAX have confirmed the presence of montmorillonite in the cast films and the interactions between the two constituents. In order to evaluate the cationic dye adsorption of these films Basic Yellow 28 was used, showing that the films have higher adsorption capacity compared to the others reported in the literature. The results were fitted into Langmuir, Freundlich and Temkin isotherms indicating an exothermic process and setting the optimum amount of montmorillonite in the films to 30% of pectin mass. According to the Langmuir isotherm the maximum adsorption capacity is 571.4 mg/g. PMID:24268651

Nesic, Aleksandra R; Velickovic, Sava J; Antonovic, Dusan G

2014-04-01

90

SpiderCast: a scalable interest-aware overlay for topic-based pub\\/sub communication  

Microsoft Academic Search

We introduce SpiderCast, a distributed protocol for con- structing scalable churn-resistant overlay topologies for sup- porting decentralized topic-based pub\\/sub communication. SpiderCast is designed to efiectively tread the balance be- tween average overlay degree and communication cost of event dissemination. It employs a novel coverage-optimizing heuristic in which the nodes utilize partial subscription views (provided by a decentralized membership service) to

Gregory Chockler; Roie Melamed; Yoav Tock; Roman Vitenberg

2007-01-01

91

Comparison of Release-Controlling Efficiency of Polymeric Coating Materials Using Matrix-type Casted Films and Diffusion-Controlled Coated Tablet  

Microsoft Academic Search

Polymeric coating materials have been widely used to modify release rate of drug. We compared physical properties and release-controlling\\u000a efficiency of polymeric coating materials using matrix-type casted film and diffusion-controlled coated tablet. Hydroxypropylmethyl\\u000a cellulose (HPMC) with low or high viscosity grade, ethylcellulose (EC) and Eudragit® RS100 as pH-independent polymers and\\u000a Eudragit S100 for enteric coatings were chosen to prepare the

Zong-Zhu Piao; Kyoung-Ho Lee; Dong-Jin Kim; Hong-Gu Lee; Jaehwi Lee; Kyung Taek Oh; Beom-Jin Lee

2010-01-01

92

Investigation on the dissolution of ? phase in a cast Ni-based superalloy  

NASA Astrophysics Data System (ADS)

The dissolution behavior of ? phase has been investigated in a cast Ni-based superalloy. The results showed that the platelets and blocks of ? phase were formed within the interdendritic regions of the microstructure. Applying standard solution annealing at 1150-1160°C for a period of 4 h did not result in the complete dissolution of ? phase. For the complete dissolution of ? phase without residual incipient melting, a 2-step solution annealing has been recommended. After dissolution at high temperatures, the ? phase transforms to two MC-type carbides: one is enriched in Ti, Nb, and Ta, and the other is of (Zr,Ti)C type.

Jahangiri, M. R.; Arabi, H.; Boutorabi, S. M. A.

2013-01-01

93

Evaluation of electroslag castings  

SciTech Connect

Results of evaluations of electroslag castings of ferritic (2-1/4 Cr-1 Mo and 9 Cr-1 Mo) and austenitic (CF8M or type 316) steels are presented. The castings have been characterized for surface finish, cracking, solidification structure, chemical composition, hardness, ferrite distribution, tensile properties, Charpy impact properties, and creep properties. Pertinent data are compared with equivalent data for sand castings and wrought products of the same materials. Based on the results of these studies, the properties of electroslag castings compare favorably with those of sand castings and wrought materials.

Judkins, R.R.; Sikka, V.K.

1985-01-01

94

Classification techniques based on AI application to defect classification in cast aluminum  

NASA Astrophysics Data System (ADS)

This paper describes the Artificial Intelligent techniques applied to the interpretation process of images from cast aluminum surface presenting different defects. The whole process includes on-line defect detection, feature extraction and defect classification. These topics are discussed in depth through the paper. Data preprocessing process, as well as segmentation and feature extraction are described. At this point, algorithms employed along with used descriptors are shown. Syntactic filter has been developed to modelate the information and to generate the input vector to the classification system. Classification of defects is achieved by means of rule-based systems, fuzzy models and neural nets. Different classification subsystems perform together for the resolution of a pattern recognition problem (hybrid systems). Firstly, syntactic methods are used to obtain the filter that reduces the dimension of the input vector to the classification process. Rule-based classification is achieved associating a grammar to each defect type; the knowledge-base will be formed by the information derived from the syntactic filter along with the inferred rules. The fuzzy classification sub-system uses production rules with fuzzy antecedent and their consequents are ownership rates to every defect type. Different architectures of neural nets have been implemented with different results, as shown along the paper. In the higher classification level, the information given by the heterogeneous systems as well as the history of the process is supplied to an Expert System in order to drive the casting process.

Platero, Carlos; Fernandez, Carlos; Campoy, Pascual; Aracil, Rafael

1994-11-01

95

Plasticizer effects on physical-mechanical properties of solvent cast Soluplus® films.  

PubMed

Soluplus® is a novel amphiphilic polymer that has been shown to enhance the solubility and drug dissolution rate of poorly soluble drugs. However, there still is a lack of information regarding the physical mechanical properties of Soluplus® with addition of the plasticizers. This study characterized the mechanical properties of Soluplus® with four different plasticizers. The plasticizers selected were polyethylene glycol 6, triethyl citrate, propylene glycol, and glycerin; they were studied at three different levels (15%, 20%, and 25% w/w). The effects of these plasticizers on the glass transition temperature, tensile strength, percent elongation, and Young's modulus of free films made from Soluplus® were measured and the toughness and ratio of tensile strength to Young's modulus were calculated. These results showed these four plasticizers are capable to plasticizing Soluplus® as indicated by the glass transition temperature lowering, tensile strength, and Young's modulus while increasing the percent elongation and film toughness. Among the plasticizers tested, polyethylene glycol 6 showed greatest changed in the mechanical properties studied. PMID:23689959

Lim, Hanpin; Hoag, Stephen W

2013-09-01

96

Novel gradient casting method provides high-throughput assessment of blended polyester poly(lactic-co-glycolic acid) thin films for parameter optimization.  

PubMed

Pure polymer films cannot meet the diverse range of controlled release and material properties demanded for the fabrication of medical implants or other devices. Additives are added to modulate and optimize thin films for the desired qualities. To characterize the property trends that depend on additive concentration, an assay was designed which involved casting a single polyester poly(lactic-co-glycolic acid) (PLGA) film that blends a linear gradient of any PLGA-soluble additive desired. Four gradient PLGA films were produced by blending polyethylene glycol or the more hydrophobic polypropylene glycol. The films were made using a custom glass gradient maker in conjunction with a 180 cm film applicator. These films were characterized in terms of thickness, percent additive, total polymer (PLGA+additive), and controlled drug release using drug-like fluorescent molecules such as coumarin 6 (COU) or fluorescein diacetate (FDAc). Material properties of elongation and modulus were also accessed. Linear gradients of additives were readily generated, with phase separation being the limiting factor. Additive concentration had a Pearson's correlation factor (R) of >0.93 with respect to the per cent total release after 30 days for all gradients characterized. Release of COU had a near zero-order release over the same time period, suggesting that coumarin analogs may be suitable for use in PLGA/polyethylene glycol or PLGA/polypropylene glycol matrices, with each having unique material properties while allowing tuneable drug release. The gradient casting method described has considerable potential in offering higher throughput for optimizing film or coating material properties for medical implants or other devices. PMID:22293582

Steele, Terry W J; Huang, Charlotte L; Kumar, Saranya; Irvine, Scott; Boey, Freddy Yin Chiang; Loo, Joachim S C; Venkatraman, Subbu S

2012-07-01

97

Surface analysis of cast aluminum by means of artificial vision and AI-based techniques  

NASA Astrophysics Data System (ADS)

An architecture for surface analysis of continuous cast aluminum strip is described. The data volume to be processed has forced up the development of a high-parallel architecture for high- speed image processing. An especially suitable lighting system has been developed for defect enhancing in metallic surfaces. A special effort has been put in the design of the defect detection algorithm to reach two main objectives: robustness and low processing time. These goals have been achieved combining a local analysis together with data interpretation based on syntactical analysis that has allowed us to avoid morphological analysis. Defect classification is accomplished by means of rule-based systems along with data-based classifiers. The use of clustering techniques is discussed to perform partitions in Rn by SOM, divergency methods to reduce the feature vector applied to the data-based classifiers. The combination of techniques inside a hybrid system leads to near 100% classification success.

Platero, Carlos; Fernandez, Carlos; Campoy, Pascual; Aracil, Rafael

1996-02-01

98

Cast aluminized explosives (review)  

Microsoft Academic Search

This paper reviews the current status and future trends of aluminized explosives. The major focus is on cast compositions,\\u000a which encompass both the melt-cast trinitrotoluene (TNT) based and the slurry cast polymer-based compositions. Widely reported\\u000a RDX and HMX based aluminized compositions with TNT used as a binder are discussed in detail. Various researchers have suggested\\u000a a 15–20% Al content as

P. P. Vadhe; R. B. Pawar; R. K. Sinha; S. N. Asthana; A. Subhananda Rao

2008-01-01

99

Fuzzy rule based classification and quantification of graphite inclusions from microstructure images of cast iron.  

PubMed

The quantification of three classes of graphite inclusions in cast iron, namely, nodular, flake, and irregular, is the most important process in the foundry industry. This classification is based on the ISO 945 proposed morphology of graphite inclusions. This work presents a novel solution for automatic quantitative analysis of graphite inclusions into the three mentioned classes. The proposed work comprises three stages, namely, preprocessing of micrographs, classification of graphite inclusions, and then quantification of inclusions in each class. An effort has been made in this work to propose a minimum set of features to represent graphite inclusion morphology. The method employs just two geometric shape descriptors: the diameter ratio and the area ratio. A fuzzy rule based classifier is built using known feature values that are efficient in the classification of the three classes of graphite inclusions. The proposed method is automatic, fast, and provides the basis for determining many more morphological parameters that can be determined with the least effort. The results obtained by the proposed method are compared with the manual method. It is observed that the results obtained from the proposed method are useful in the optimization of cast iron manufacturing in the foundry industry. PMID:22053909

Prakash, Pattan; Mytri, V D; Hiremath, P S

2011-12-01

100

New approaches in microcasting: permanent mold casting and composite casting  

Microsoft Academic Search

For several years, microcasting was based on investment casting. New approaches are now the permanent mold casting and composite\\u000a casting of micro parts. Casting was performed with aluminum bronze of the type CuAl10Ni5Fe4. Permanent mold casting was commenced with steel mold inserts in a lost mold. The development of a band heater enabled the\\u000a heating of permanent molds inside the

G. Baumeister; D. Buqezi-Ahmeti; J. Glaser; H.-J. Ritzhaupt-Kleissl

2011-01-01

101

Layer bonding of solvent-cast thin films for pharmaceutical solid dosage forms  

E-print Network

In the pharmaceutical industry, the conventional tablet manufacturing process, a batch-based process based on solid powder handling, presents challenges such as inhomogeneous blending between Active Pharmaceutical Ingredients ...

Kim, Won, S.M. Massachusetts Institute of Technology

2010-01-01

102

Microstructure/mechanical property relationship in a DS Cast Ni3Al-base alloy  

NASA Astrophysics Data System (ADS)

A Ni-Al-Mo directionally solidified (DS) casting ?-base superalloy, with the chemical composition (wt %) 7.5 to 8.5% Ni, 10 to 14% Al, Mo ?0.15% B, has been developed for advanced gas turbine blades and vanes. The mechanical properties of this alloy have been determined by tensile tests at room temperature and in the temperature range 700 to 1000 °C and by stress-rupture tests in the temperature range 760 to 1100 °C. The microstructures of the as-cast and homogenized specimens and of specimens after creep de-formation at 1000 to 1100 °C have been examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy techniques. The results show that this alloy has a high yield strength from room temperature up to 1100 °C, excellent creep resistance at temperatures up to 1100 °C, as well as a lower density and higher melting point than currently available nickel superal-loys. The microstructural observations and analysis indicate that the superior mechanical properties of this alloy may be attributed to solid solution hardening by the large molybdenum addition, second-phase strengthening by y phase and other minor phases that precipitate in various temperature ranges, the for-mation of a ? raft structure during creep, and to the existence of high-density misfit dislocation networks at ? / ? interface areas due to a high value of ? / ? misfit.

Han, Y. F.; Wang, Y. M.; Chaturvedi, M. C.

1993-08-01

103

Oxide dispersion in direct-cast gamma TiAl-based alloy  

SciTech Connect

The objective of this study is to evaluate the high temperature behavior of {gamma} TiAl-based alloy sheets containing Al{sub 2}O{sub 3} particles, produced by a combination of vacuum induction melting, use of a CaO crucible, and direct sheet casting, over a wide temperature range. Alumina particles, having a tendency to coagulate during solidification of a TiAl ingot, are finely dispersed due to the disturbance of high frequency induction, and frozen without having enough time to grow in size by direct sheet casting. The TiAl sheet thus produced shows remarkable high temperature tensile strength which exceeds that of conventional ingots having the same composition and various different structures. This is determined to be attributable to the dispersion strengthening of finely dispersed Al{sub 2}O{sub 3} particles whose diameter is from 100 to 500nm. Moreover, because of the small size of these alumina particles, the TiAl sheet does not show any significant retardation in high temperature ductility, which is often the case in conventional ceramic reinforced intermetallic compound composites.

Hanamura, Toshihiro; Hashimoto, Keizo [Nippon Steel Corp., Kawasaki (Japan). Advanced Technology Research Labs.

1995-07-01

104

Drug release profiles and microstructural characterization of cast and freeze dried vitamin B12 buccal films by positron annihilation lifetime spectroscopy.  

PubMed

Solvent cast and freeze dried films, containing the water-soluble vitamin B12 as model drug were prepared from two polymers, sodium alginate (SA), and Carbopol 71G (CP). The proportion of the CP was changed in the films. The microstructural characterization of various samples was carried out by positron annihilation lifetime spectroscopy (PALS). The drug release kinetics of untreated and stored samples was evaluated by the conventionally applied semi-empirical power law. Correlation was found between the changes of the characteristic parameters of the drug release and the ortho-positronium (o-Ps) lifetime values of polymer samples. The results indicated that the increase of CP concentration, the freeze-drying process and the storage at 75% R.H. decreased the rate of drug release. The PALS method enabled the distinction between the micro- and macrostructural factors influencing the drug release profile of polymer films. PMID:24269613

Szabó, Barnabás; Kállai, Nikolett; Tóth, Gerg?; Hetényi, Gergely; Zelkó, Romána

2014-02-01

105

Evaluation of three variables affecting the casting of base metal alloys.  

PubMed

All the vented samples with sprue widths of 2 mm or more were defect free, whereas the corresponding unvented samples had extensive voids and porosity in all but one casting. All castings with a sprue width of 1 mm were defective regardless of whether or not vents were used. The thickness of the investment above the pattern had no effect on casting results. PMID:6987385

Wight, T A; Grisius, R J; Gaugler, R W

1980-04-01

106

Fabrication of a zirconia MEMS-based microthruster by gel casting on PDMS soft molds  

NASA Astrophysics Data System (ADS)

A zirconia microelectromechanical-system-based microthruster was fabricated through a newly developed fabrication route. Gel casting of homogenously dispersed zirconia suspension on polydimethylsiloxane soft mold was utilized to replicate the geometries of microthruster design onto a ceramic layer of about 1.2 mm thick. Lamination of the patterned ceramic layer to another flat ceramic layer and subsequent sintering produced the microthruster. Characterizations on the fabricated prototype showed good shape retention on the replicated geometries and good quality of lamination. Shrinkage of about 10-15% was noted after sintering. The current fabrication route is particularly promising for the development of high-performance micropropulsion systems which require their structural material to survive in an extreme environment which is corrosive, of high temperature and highly oxidative.

Cheah, K. H.; Khiew, P. S.; Chin, J. K.

2012-09-01

107

Poly(vinyl alcohol)-based film potentially suitable for antimicrobial packaging applications.  

PubMed

This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 ?m in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances. PMID:24611868

Musetti, Alessandro; Paderni, Katia; Fabbri, Paola; Pulvirenti, Andrea; Al-Moghazy, Marwa; Fava, Patrizia

2014-04-01

108

Development of NZP ceramic based {open_quotes}cast-in-place{close_quotes} diesel engine port liners  

SciTech Connect

BSX (Ba{sub 1+x}Zr{sub 4}P{sub 6-2x}Si{sub 2x}O{sub 24}) and CSX (Ca{sub l-x}Sr{sub x}Zr{sub 4}P{sub 6}O{sub 24}) type NZP ceramics were fabricated and characterized for: (i) thermal properties viz., thermal conductivity, thermal expansion, thermal stability and thermal shock resistance; (ii) mechanical properties viz., flexure strength and elastic modulus; and (iii) microstructures. Results of these tests and analysis indicated that the BS-25 (x=0.25 in BSX) and CS-50 (x=0.50 in CSX) ceramics had the most desirable properties for casting metal with ceramic in place. Finite element analysis (FEA) of metal casting (with ceramic in place) was conducted to analyze thermomechanical stresses generated and determine material property requirements. Actual metal casting trials were also conducted to verify the results of finite element analysis. In initial trials, the ceramic cracked because of the large thermal expansion mismatch (hoop) stresses (predicted by FEA also). A process for introduction of a compliant layer between the metal and ceramic to alleviate such destructive stresses was developed. The compliant layer was successful in preventing cracking of either the ceramic or the metal. In addition to these achievements, pressure slip casting and gel-casting processes for fabrication of NZP components; and acoustic emission and ultrasonics-based NDE techniques for detection of microcracks and internal flaws, respectively, were successfully developed.

Nagaswaran, R.; Limaye, S.Y.

1996-02-01

109

Development of model for barrier and optical properties of tapioca starch based edible films.  

PubMed

The film forming solutions composed of tapioca (cassava) starch (1-3 g), glycerol (0.5-1.0 ml), agar (0.5-1.0 g) and span 80 (0.1-0.5 ml) were prepared according to a three-level, four-factor Box-Behnken response surface experimental design. The films were obtained by casting method and they are homogenous and transparent. The influence of film composition (tapioca starch, glycerol, agar and span80) on the barrier and optical properties of the tapioca starch based edible films was evaluated. The results showed that, hydrophilic nature and plasticizing effect of glycerol increases the water vapor permeability, oxygen permeability, moisture content, solubility and swelling capacity of the films. But surfactant (span80) incorporation reduces the mobility of the polysaccharide matrix and decreases the barrier properties of the films. Transparency of the films was influenced by plasticizer and surfactant concentration due to the dilution effect of glycerol and span80. The results were analyzed by Pareto analysis of variance (ANOVA) and second-order polynomial models were developed using multiple regression analysis. The models developed from the experimental design were predictive and good fit with the experimental data with high coefficient of determination (R(2)) values (more than 0.95). The optimized conditions were obtained were tapioca starch of 1.95 g, glycerol of 0.8 ml, agar of 0.7 g and span 80 of 0.3 ml, respectively. PMID:23399163

Maran, J Prakash; Sivakumar, V; Sridhar, R; Thirugnanasambandham, K

2013-02-15

110

High Throughput Prioritization for Integrated Toxicity Testing Based on ToxCast Chemical Profiling  

EPA Science Inventory

The rational prioritization of chemicals for integrated toxicity testing is a central goal of the U.S. EPA?s ToxCast? program (http://epa.gov/ncct/toxcast/). ToxCast includes a wide-ranging battery of over 500 in vitro high-throughput screening assays which in Phase I was used to...

111

A general and robust ray-casting-based algorithm for triangulating surfaces at the nanoscale.  

PubMed

We present a general, robust, and efficient ray-casting-based approach to triangulating complex manifold surfaces arising in the nano-bioscience field. This feature is inserted in a more extended framework that: i) builds the molecular surface of nanometric systems according to several existing definitions, ii) can import external meshes, iii) performs accurate surface area estimation, iv) performs volume estimation, cavity detection, and conditional volume filling, and v) can color the points of a grid according to their locations with respect to the given surface. We implemented our methods in the publicly available NanoShaper software suite (www.electrostaticszone.eu). Robustness is achieved using the CGAL library and an ad hoc ray-casting technique. Our approach can deal with any manifold surface (including nonmolecular ones). Those explicitly treated here are the Connolly-Richards (SES), the Skin, and the Gaussian surfaces. Test results indicate that it is robust to rotation, scale, and atom displacement. This last aspect is evidenced by cavity detection of the highly symmetric structure of fullerene, which fails when attempted by MSMS and has problems in EDTSurf. In terms of timings, NanoShaper builds the Skin surface three times faster than the single threaded version in Lindow et al. on a 100,000 atoms protein and triangulates it at least ten times more rapidly than the Kruithof algorithm. NanoShaper was integrated with the DelPhi Poisson-Boltzmann equation solver. Its SES grid coloring outperformed the DelPhi counterpart. To test the viability of our method on large systems, we chose one of the biggest molecular structures in the Protein Data Bank, namely the 1VSZ entry, which corresponds to the human adenovirus (180,000 atoms after Hydrogen addition). We were able to triangulate the corresponding SES and Skin surfaces (6.2 and 7.0 million triangles, respectively, at a scale of 2 grids per Å) on a middle-range workstation. PMID:23577073

Decherchi, Sergio; Rocchia, Walter

2013-01-01

112

Microstructural and mechanical properties of nickel-base plasma sprayed coatings on steel and cast iron substrates  

Microsoft Academic Search

This paper studies the phase composition, microstructure, hardness and wear resistance of nickel-base plasma sprayed coatings, on two types of substrates, steel and cast iron. The processing method of metal and compound powders for plasma spraying is detailed, together with the characteristics of the powders before and after processing. It has been found that in as-coated condition, the surface layers

H. Skulev; S. Malinov; W. Sha; P. A. M. Basheer

2005-01-01

113

Production and properties of nanocellulose-reinforced methylcellulose-based biodegradable films.  

PubMed

Methylcellulose (MC)-based films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol, and 0.025% Tween 80. Puncture strength (PS), puncture deformation (PD), viscoelasticity coefficient, and water vapor permeability (WVP) were found to be 147 N/mm, 3.46 mm, 41%, and 6.34 g.mm/m(2).day.kPa, respectively. Aqueous nanocellulose (NC) solution (0.1-1%) was incorporated into the MC-based formulation, and it was found that PS was improved (117%) and WVP was decreased (26%) significantly. Films containing 0.25% NC were found to be the optimum. Then films were exposed to gamma radiation (0.5-50 kGy), and it was revealed that mechanical properties of the films were slightly decreased after irradiation, whereas barrier properties were further improved with a decrease of WVP to 28.8% at 50 kGy. Molecular interactions due to incorporation of NC were supported by FTIR spectroscopy. Thermal properties of the NC-containing films were improved, confirmed by TGA and DSC. Crystalline peaks appeared due to NC addition, found by XRD. Micrographs of films containing NC were investigated by SEM. PMID:20545366

Khan, Ruhul A; Salmieri, Stephane; Dussault, Dominic; Uribe-Calderon, Jorge; Kamal, Musa R; Safrany, Agnes; Lacroix, Monique

2010-07-14

114

Structure–property-processing investigations of the tenter-frame process for making biaxially oriented HDPE film. I. Base sheet and draw along the MD  

Microsoft Academic Search

We discuss here the first two stages of the tenter-frame film manufacturing process for HDPE, viz. (a) the extrusion of the polymer onto a cooled cast roll (base sheet) and (b) drawing along the machine direction (MD) using several sets of rolls (referred to as machine draw orientation (MDO) sheet). The structure–property relationships are analyzed for a single resin when

Varun Ratta; Garth L. Wilkes; T. K. Su

2001-01-01

115

UV detector based on polycrystalline diamond films  

NASA Astrophysics Data System (ADS)

Unlike other conventional photoconductive detectors, diamond-based devices provide high discrimination between UV and visible radiation. In this work we present the optical and electrical properties of devices based on randomly oriented diamond films, synthesized by microwave plasma enhanced chemical vapor deposition. It was observed that the UV detectors displayed low dark currents, high discrimination for wavelengths longer than 230 nm, high sensitivity and speed.

Girija, K. G.; Nuwad, J.

2013-02-01

116

Biodegradable packages development from starch based heat sealable films  

Microsoft Academic Search

Heat sealing capacity of native and acetylated corn starch based films was evaluated to develop biodegradable packages, such as bags. Thermo-mechanical properties were analyzed since they condition their handling and applications. Acetylated starch addition reinforced 80% sealing resistance of starch films. Unplasticized heat-sealed films presented adhesive failures while those containing glycerol showed a rupture near the zip. Unplasticized films exhibited

Olivia V. López; Carlos J. Lecot; Noemí E. Zaritzky; María A. García

2011-01-01

117

Anisotropy in structural and physical properties in tetrathiafulvalene derivatives-based zone-cast layers as seen by Raman spectroscopy, UV-visible spectroscopy, and field effect measurements  

NASA Astrophysics Data System (ADS)

We have studied anisotropy of thin layers of amphiphilic tetrathiafulvalene derivatives (TTF-4SCn, with n=12, 18, and 22) obtained by zone-casting technique. All the films show optical anisotropy, as seen by polarized optical microscopy and polarized UV-visible spectroscopy. By using polarized Raman spectroscopy an angular dependence of intensity of different vibrational modes in respect to the zone-casting direction was determined. It was found that intensities of the modes related to central and ring C=C vibrations in the TTF core depend very strongly on the angle between the zone-cast direction and polarization plane of incident laser light. Comparison of the deduced orientation of the molecules in one of the films (TTF-4SC18) with its crystal structure shows that the polarized Raman spectroscopy can be useful for controlling orientation of molecules in thin films (e.g., for online monitoring). Organic field effect transistors (OFETs), with channels oriented in parallel and perpendicularly to the zone-casting direction, were built using the oriented TTF-4SCn films. In all cases a strong anisotropy of the charge carrier mobility (?) was found; the best results were obtained for OFETs with TTF-4SC18, for which ??=0.25 cm2/V s, ON/OFF>105, and ??/???170.

Kotarba, Sylwia; Jung, Jaroslaw; Kowalska, Aneta; Marszalek, Tomasz; Kozanecki, Marcin; Miskiewicz, Pawel; Mas-Torrent, Marta; Rovira, Concepció; Veciana, Jaume; Puigmarti-Luis, Josep; Ulanski, Jacek

2010-07-01

118

Analysis of mechanical characteristics of the ionic polymer metal composite (IPMC) actuator using cast ion-exchange film  

Microsoft Academic Search

IPMC (Ionic Polymer Metal Composite) is a promising candidate actuator for bio-related applications mainly due to its biocompatibility, soft properties and operation in wet condition. The widely used and commercialized ion-exchange polymer film has limitation in thicknesses, but more various film thicknesses are required for extensive applications. Especially for the enhanced force as an actuator, acquisition of thick film is

Byungkyu Kim; Byung M. Kim; Jaewook Ryu; In-Hwan Oh; Seung-Ki Lee; Seung-Eun Cha; Jungho Pak

2003-01-01

119

High-throughput models for exposure-based chemical prioritization in the ExpoCast project.  

PubMed

The United States Environmental Protection Agency (U.S. EPA) must characterize potential risks to human health and the environment associated with manufacture and use of thousands of chemicals. High-throughput screening (HTS) for biological activity allows the ToxCast research program to prioritize chemical inventories for potential hazard. Similar capabilities for estimating exposure potential would support rapid risk-based prioritization for chemicals with limited information; here, we propose a framework for high-throughput exposure assessment. To demonstrate application, an analysis was conducted that predicts human exposure potential for chemicals and estimates uncertainty in these predictions by comparison to biomonitoring data. We evaluated 1936 chemicals using far-field mass balance human exposure models (USEtox and RAIDAR) and an indicator for indoor and/or consumer use. These predictions were compared to exposures inferred by Bayesian analysis from urine concentrations for 82 chemicals reported in the National Health and Nutrition Examination Survey (NHANES). Joint regression on all factors provided a calibrated consensus prediction, the variance of which serves as an empirical determination of uncertainty for prioritization on absolute exposure potential. Information on use was found to be most predictive; generally, chemicals above the limit of detection in NHANES had consumer/indoor use. Coupled with hazard HTS, exposure HTS can place risk earlier in decision processes. High-priority chemicals become targets for further data collection. PMID:23758710

Wambaugh, John F; Setzer, R Woodrow; Reif, David M; Gangwal, Sumit; Mitchell-Blackwood, Jade; Arnot, Jon A; Joliet, Olivier; Frame, Alicia; Rabinowitz, James; Knudsen, Thomas B; Judson, Richard S; Egeghy, Peter; Vallero, Daniel; Cohen Hubal, Elaine A

2013-08-01

120

High-cycle fatigue-life of the cast nickel base-superalloys in 738 LC and IN 939  

Microsoft Academic Search

The high cycle fatigue (HCF) properties of two cast nickel base-superalloys, IN 738 LC and IN 939, were investigated using\\u000a both fracture mechanics samples and smooth specimens. The crack propagation behavior was studied in terms of linear fracture\\u000a mechanics at RT and at 850 C. In addition to the influence of temperature, the influences of frequency, mean stress, and\\u000a environment

W. Hoffelner

1982-01-01

121

Measurement of concrete E-modulus evolution since casting: A novel method based on ambient vibration  

SciTech Connect

The use of ambient vibration tests to characterize the evolution of E-modulus of concrete right after casting is investigated in this paper. A new methodology is proposed, which starts by casting a concrete cylindrical beam inside a hollow acrylic formwork. This beam is then placed horizontally, simply supported at both extremities, and vertical accelerations resulting from ambient vibration are measured at mid-span. Processing these mid-span acceleration time series using power spectral density functions allows a continuous identification of the first flexural frequency of vibration of the composite beam, which in turn is correlated with the evolutive E-modulus of concrete since casting. Together with experiments conducted with the proposed methodology, a complementary validation campaign for concrete E-modulus determination was undertaken by static loading tests performed on the composite beam, as well as by standard compressive tests of concrete cylinders of the same batch loaded at different ages.

Azenha, Miguel, E-mail: miguel.azenha@civil.uminho.p [LABEST - Laboratory for the Concrete Technology and Structural Behaviour, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); ISISE - Institute for Sustainability and Innovation in Structural Engineering, Universidade do Minho, Escola de Engenharia, Campus de Azurem, 4800-058 Guimaraes (Portugal); Magalhaes, Filipe [VIBEST - Laboratory of Vibrations and Structural Monitoring, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Faria, Rui [LABEST - Laboratory for the Concrete Technology and Structural Behaviour, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); Cunha, Alvaro [VIBEST - Laboratory of Vibrations and Structural Monitoring, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)

2010-07-15

122

Polyelectrolyte films based on chitosan/olive oil and reinforced with cellulose nanocrystals.  

PubMed

Composite films designed as potentially edible food packaging were prepared by casting film-forming emulsions based on chitosan/glycerol/olive oil containing dispersed cellulose nanocrystals (CNs). The combined use of cellulose nanoparticles and olive oil proved to be an efficient method to reduce the inherently high water vapor permeability of plasticized chitosan films, improving at the same time their tensile behavior. At the same time, it was found that the water solubility slightly decreased as the cellulose content increased, and further decreased with oil addition. Unexpectedly, opacity decreased as cellulose content increased, which balanced the reduced transparency due to lipid addition. Contact angle decreased with CN addition, but increased when olive oil was incorporated. Results from dynamic mechanical tests revealed that all films present two main relaxations that could be ascribed to the glycerol- and chitosan-rich phases, respectively. The response of plasticized chitosan-nanocellulose films (without lipid addition) was also investigated, in order to facilitate the understanding of the effect of both additives. PMID:24299870

Pereda, Mariana; Dufresne, Alain; Aranguren, Mirta I; Marcovich, Norma E

2014-01-30

123

Assessing the Robustness of Chemical Prioritizations Based on ToxCast Chemical Profiling  

EPA Science Inventory

A central goal of the U.S. EPA?s ToxCast? program is to provide empirical, scientific evidence to aid in prioritizing the toxicity testing of thousands of chemicals. The agency has developed a prioritization approach, the Toxicological Prioritization Index (ToxPi?), that calculat...

124

The use of fluidized sand bed as an innovative technique for heat treating aluminum based castings  

NASA Astrophysics Data System (ADS)

The current study was carried out to arrive at a better understanding of the influences of the fluidized sand bed heat treatment on the tensile properties and quality indices of A356.2 and B319.2 casting alloys. For the purposes of validating the use of fluidized sand bed furnaces in industrial applications for heat treatment of 356 and 319 castings, the tensile properties and the quality indices of these alloys were correlated with the most common metallurgical parameters, such as strontium modification, grain refining, solutionizing time, aging parameters and quenching media. Traditional heat treatment technology, employing circulating air convection furnaces, was used to establish a relevant comparison with fluidized sand beds for the heat treatment of the alloys investigated, employing T6 continuous aging cycles or multi-temperature aging cycles. Quality charts were used to predict and/or select the best heat treatment conditions and techniques to be applied in industry in order to obtain the optimum properties required for particular engineering applications. The results revealed that the strength values achieved in T6-tempered 319 and 356 alloys are more responsive to fluidized bed (FB) heat treatment than to conventional convection furnace (CF) treatment for solution treatment times of up to 8 hours. Beyond this solution time, no noticeable difference in properties is observed with the two techniques. A significant increase in strength is observed in the FB heat-treated samples after short aging times of 0.5 and 1 hour, the trend continuing up to 5 hours. The 319 alloys show signs of overaging after 8 hours of aging using a conventional furnace, whereas with a fluidized bed, overaging occurs after 12 hours. Analysis of the tensile properties in terms of quality index charts showed that both modified and non-modified 319 and 356 alloys display the same, or better, quality, after only a 2-hr treatment in an FB compared to 10 hours when using a CF. The quality values of the 356 alloys are more responsive to the FB technique than 319 alloys through long aging times of up to 5 hours. The 319 alloys heat-treated in an FB, however, show better quality values after 0.5 hour of aging and for solution treatment times of up to 5 hours than those treated using a CF. With regard to the quality charts of 319 alloys, heat-treated samples show that increasing the aging time up to peak-strength, i.e. 8 and 12 hours in a CF and an FB, respectively, results in increasing in the alloy strength with a decrease in the quality values, for each of the solution heat treatment times used. The statistical analysis of the results reveals that modification and heating rate of the heat treatment technique have the greatest positive effects on the quality values of the 356 alloys. The use of a fluidized sand bed for the direct quenching-aging treatment of A356.2 and B319.2 casting alloys yields greater UTS and YS values compared to conventional furnace quenched alloys. The strength values of T6 tempered A356 and B319 alloys are greater when quenched in water compared to those quenched in an FB or CF. For the same aging conditions (170°C/4h), the fluidized bed quenched-aged 319 and 356 alloys show nearly the same or better strength values than those quenched in water and then aged in a CF or an FB. Based on the quality charts developed for alloys subjected to different quenching media, higher quality index values are obtained by water-quenched T6-tempered A356 alloys, and conventional furnace quenched-aged T6-tempered B319 alloys, respectively. The modification factor has the most significant effect on the quality results of the alloys investigated, for all heat treatment cycles, as compared to other metallurgical parameters. The results of alloys subjected to multi-temperature aging cycles reveal that the strength results obtained after the T6 continuous aging treatment of A356 alloys are not improved by means of multi-temperature aging cycles, indicating therefore that the optimum properties are obtained using a T6 aging treatment. The optimu

Ragab, Khaled

125

Polyox and carrageenan based composite film dressing containing anti-microbial and anti-inflammatory drugs for effective wound healing.  

PubMed

Polyethylene oxide (Polyox) and carrageenan based solvent cast films have been formulated as dressings for drug delivery to wounds. Films plasticised with glycerol were loaded with streptomycin (30%, w/w) and diclofenac (10%, w/w) for enhanced healing effects in chronic wounds. Blank and drug loaded films were characterised by texture analysis (for mechanical and mucoadhesive properties), scanning electron microscopy, differential scanning calorimetry, X-ray diffraction and Fourier transform infrared spectroscopy. In addition, swelling, in vitro drug release and antibacterial studies were conducted to further characterise the films. Both blank and drug loaded films showed a smooth, homogeneous surface morphology, excellent transparency, high elasticity and acceptable tensile (mechanical) properties. The drug loaded films showed a high capacity to absorb simulated wound fluid and significant mucoadhesion force which is expected to allow effective adherence to and protection of the wound. The films showed controlled release of both streptomycin and diclofenac for 72 h. These drug loaded films produced higher zones of inhibition against Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli compared to the individual drugs zones of inhibition. Incorporation of streptomycin can prevent and treat chronic wound infections whereas diclofenac can target the inflammatory phase of wound healing to relieve pain and swelling. PMID:23228898

Boateng, Joshua S; Pawar, Harshavardhan V; Tetteh, John

2013-01-30

126

Fabrication of x-ray absorption gratings via micro-casting for grating-based phase contrast imaging  

NASA Astrophysics Data System (ADS)

Grating-based x-ray differential phase contrast (DPC) imaging has shown huge potential. For broad applications, it is essential that the key components are low-cost, especially the absorption gratings. We therefore proposed and developed a micro-casting process for fabricating x-ray absorption gratings with bismuth. This process is feasible for mass production at low cost, with a large format, and a high aspect ratio. To develop this kind of absorption grating, an array with deep trenches was fabricated by photo-assisted electrochemical etching in a silicon wafer. The trenches were then filled with bubble-free, molten bismuth via capillary action and surface tension. Bismuth was attractive as a filling material because of its great mass absorption coefficient, low cost and broad environmental compatibility. Furthermore, our micro-casting process provided bismuth absorption gratings with a clean surface and no need for post treatment. To test their performance in x-ray DPC imaging, two bismuth absorption gratings, one as a periodic source and another as the analyzer, were used with periods of 42 and 3 µm and depths of 110 and 150 µm, respectively. The acquired phase-contrast images demonstrated that the micro-casting process produces qualified gratings for x-ray DPC imaging.

Lei, Yaohu; Du, Yang; Li, Ji; Zhao, Zhigang; Liu, Xin; Guo, Jinchuan; Niu, Hanben

2014-01-01

127

Clean Metal Casting  

SciTech Connect

The objective of this project is to develop a technology for clean metal processing that is capable of consistently providing a metal cleanliness level that is fit for a given application. The program has five tasks: Development of melt cleanliness assessment technology, development of melt contamination avoidance technology, development of high temperature phase separation technology, establishment of a correlation between the level of melt cleanliness and as cast mechanical properties, and transfer of technology to the industrial sector. Within the context of the first task, WPI has developed a standardized Reduced Pressure Test that has been endorsed by AFS as a recommended practice. In addition, within the context of task1, WPI has developed a melt cleanliness sensor based on the principles of electromagnetic separation. An industrial partner is commercializing the sensor. Within the context of the second task, WPI has developed environmentally friendly fluxes that do not contain fluorine. Within the context of the third task, WPI modeled the process of rotary degassing and verified the model predictions with experimental data. This model may be used to optimize the performance of industrial rotary degassers. Within the context of the fourth task, WPI has correlated the level of melt cleanliness at various foundries, including a sand casting foundry, a permanent mold casting foundry, and a die casting foundry, to the casting process and the resultant mechanical properties. This is useful in tailoring the melt cleansing operations at foundries to the particular casting process and the desired properties of cast components.

Makhlouf M. Makhlouf; Diran Apelian

2002-02-05

128

Effects of Block Length and Solution-Casting Conditions on the Final Morphology and Properties of Disulfonated Poly(arylene ether sulfone) Multiblock Copolymer Films for Proton Exchange Membranes  

SciTech Connect

The effects of block length and solution-casting conditions on the final microstructures and properties of disulfonated poly(arylene ether sulfone) multiblock copolymer (BPSH100-BPS0) films for proton exchange membranes were investigated based on the basic principles of microstructure formation of block copolymers. Morphological studies using transmission electron microscopy and small angle X-ray scattering demonstrated that as the block length increased, the inter-ionic-domain distance increased, with a subsequent increase in lamellar ordering and long-range continuity. Further enhancement in morphological order was achieved by simply utilizing a selective solvent, dimethylacetamide, which is good and marginal for the sulfonated and unsulfonated blocks, respectively, rather than a neutral solvent, N-metyl-2-pyrrolidone. These morphological enhancements led to higher proton conductivity and water uptake. Drying temperature and/or solvent removal rate were observed to have considerable effects on water uptake and swelling behavior, being coupled with solvent selectivity. Also, the multiblock copolymer consisting of longer blocks was found to be more sensitive to the variation of the processing conditions such as solvent type and film drying temperature.

Lee, M.; Park, J; Lee, H; Lane, O; Moore, R; McGrath, J; Baird, D

2009-01-01

129

Thin-film-based dispersion compensation technology and challenges  

NASA Astrophysics Data System (ADS)

Thin-film (TF) based dispersion compensators are of necessity some form of allpass filter. Whether these allpass filters are cast in the form of a coupled or a cascaded cavity structure, they can provide compact, low-loss, and highly stable dispersion compensation thereby having the potential of becoming important future components in both optical time-division multiplexing (OTDM) and wavelength division multiplexing (WDM) systems. In this paper, the salient points in the development of these devices are discussed up to the present state of the technology. Particular emphasis is placed on TF coupled cavity allpass (CCAP) filters as devices that provide only third-order dispersion compensation (TODC), having a group delay response that is purely quadratic. These CCAP filters are shown to have evolved over a number of important steps, from a hybrid two-cavity device, to a completely TF two-cavity single-surface filter, and finally to a dual-surface multi-reflection four-cavity device. The adjustable hybrid coupled cavity allpass filter provides TODC between 2.0 and 15.5 ps3 over a bandwidth between 3.6 and 1.2 nm respectively with a center wavelength tunable over an 8 nm range and the four-cavity multi-reflection completely TF device offers TODC between 0.37 ps3 and 3.2 ps3 over a 10 nm bandwidth with a center wavelength tunable over a 10 nm range. Important issues, such as the need to increase the TODC figure of merit, which is directly proportional to the number of cavities and the number of surface reflections, of these devices without incurring large loss penalties are discussed in the context of some of the important technological challenges that need to be addressed and solved before TF dispersion compensators can be effectively employed in optical systems as well as successfully compete with other existing dispersion-compensation technologies.

Jablonski, Mark K.; Tanaka, Yuichi; Kikuchi, Kazuro

2002-07-01

130

Polyvinyl acetate-based film coatings.  

PubMed

Polyvinyl acetate-based colloidal aqueous polymer dispersion Kollicoat(®) SR 30 D results in coatings characterized by moderate swelling behaviour, lipophilicity, pH-independent permeability for actives and high flexibility to withstand mechanical stress and is therefore used for controlled release coating. The colloidal aqueous polymer dispersion of Kollicoat(®) SR 30 D can be easily processed due to an optimal low minimum film forming temperature (MFT) of 18 °C without plasticizer addition and a thermal after-treatment (curing) of coated pellets. The drug release from Kollicoat(®) SR 30 D coated pellets was almost pH independent. Drug release could be easily adjusted by coating level or addition of soluble pore forming polymers. Physically stable Kollicoat(®) SR 30 D dispersions were obtained with the water-soluble polymers Kollidon(®) 30 and Kollicoat(®) IR up to 50% w/w. The addition of only 10% w/w triethyl citrate as plasticizer improved the flexibility of the films significantly and allowed compaction of the pellets. The drug release was almost independent of the compression force and the pellet content of the tablets. The inclusion of various tableting excipients slightly affected the drug release, primarily because of a different disintegration rate of the tablets. A combination of Kollicoat(®) SR 30 D and Kollicoat(®) IR with higher coating levels>10 mg/cm(2) is a relatively new alternative to OROS system which does not require drilling. PMID:24076229

Kolter, K; Dashevsky, A; Irfan, Muhamad; Bodmeier, R

2013-12-01

131

Casting Process Simulation Based of Interface Friction between Metallic Liquid and Die Wall  

NASA Astrophysics Data System (ADS)

Rapid Tooling (RT) is a major field in rapid prototyping manufacturing (RPM). In order to obtain metallic molds for automobile industry, ceramic shell precision casting technology is being used. Models are used in this kind of casting technology in RT in our lab. Some main factors have been analysed and estimated. MARC nonlinear finite element analysis software has been used for calculation of size change in the casting process. Selection of boundary conditions in the solidification process is the most important. There is interface friction between metallic liquid and die wall. Except influence in size change due to phase transition and cooling process, this friction force in tangential direction could give severe influence on the size change. If this factor is not considered in the calculation for size change, there is a large difference between real value and calculated value. We use this new model instead of usual contact model, a better result has been obtained. Work supported by the National Natural Science Foundation of China.

Zhang, Renji; Liu, Yuan; Xu, Da; Yan, Yongnian

1998-03-01

132

Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO3 thin film  

NASA Astrophysics Data System (ADS)

Multiferroic Bismuth Ferrite (BiFeO3) thin films with varying excess bismuth (Bi) concentration were grown by chemical solution deposition technique. Room temperature multiferroic properties (ferromagnetism, ferroelectricity, and piezoelectricity) of the deposited BiFeO3 thin films have been studied. High resolution X-ray diffraction and Raman spectroscopy studies reveal that the dominant phases formed in the prepared samples change continuously from a mixture of BiFeO3 and Fe2O3 to pure BiFeO3 phase and, subsequently, to a mixture of BiFeO3 and Bi2O3 with increase in the concentration of excess Bi from 0% to 15%. BiFeO3 thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (?-Fe2O3). Deterioration in ferroic properties of BiFeO3 thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO3 thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2 ?C/cm2 and saturation magnetization 11.66 emu/g. The switching of fine spontaneous domains with applied dc bias has been observed using piezoresponse force microscopy in BiFeO3 thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO3 thin films exhibiting the improved multiferroic properties.

Gupta, Surbhi; Tomar, Monika; Gupta, Vinay; James, A. R.; Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar

2014-06-01

133

Study on aluminium-based single films.  

PubMed

In the present paper the authors studied isolated metallic films made from the same material used for making metallic foams, and then characterised their properties. Metal films were made from a liquid aluminium alloy reinforced with ceramic particles of known concentration. Melts without such particles were also investigated. It is shown that stable films could not be made from Al-Si alloy having no particles, and just extremely thin and fragile films could be made from commercially-pure Al. In contrast, aluminium alloys containing particles such as SiC and TiB(2) allowed pulling thin, stable films, which did not rupture. Significant thinning of films was observed when the particle concentration in the melt decreased. By in situ X-ray monitoring of liquid films during pulling, film thickness and drainage effects within the liquid film could be studied. The morphology and microstructure of films was characterised after solidification. Our work shows that the question of how foams are stabilised can be studied using a simplified system such as a film, instead of having to deal with the multitude of different structural elements present in a foam. PMID:18060172

Vinod Kumar, G S; García-Moreno, F; Babcsán, N; Brothers, A H; Murty, B S; Banhart, J

2007-12-28

134

Die Casting.  

National Technical Information Service (NTIS)

Contents: Recording technical information in pressure diecasting; Influence of copper addition on the dendritic structure of ILZRO-12; Graphite innoculated alloys for pressure die casting; Zinc--The versatile metal; Removal of scales from die cooling chan...

1978-01-01

135

Hair casts  

PubMed Central

Hair casts or pseudonits are circumferential concretions, which cover the hair shaft in such a way that, it could be easily removed. They are thin, cylindrical, and elongated in length. We present an unusual case of an 8-year-old girl presenting with hair casts. Occurrence of these is unusual, and they may have varied associations. This patient was suffering from developmental delay. It is commonly misdiagnosed as and very important to differentiate from pediculosis capitis.

Parmar, Sweta S.; Parmar, Kirti S.; Shah, Bela J.

2014-01-01

136

Hair casts.  

PubMed

Hair casts or pseudonits are circumferential concretions, which cover the hair shaft in such a way that, it could be easily removed. They are thin, cylindrical, and elongated in length. We present an unusual case of an 8-year-old girl presenting with hair casts. Occurrence of these is unusual, and they may have varied associations. This patient was suffering from developmental delay. It is commonly misdiagnosed as and very important to differentiate from pediculosis capitis. PMID:25396168

Parmar, Sweta S; Parmar, Kirti S; Shah, Bela J

2014-10-01

137

Creep-rupture behavior of a developmental cast-iron-base alloy for use up to 800 deg C  

NASA Technical Reports Server (NTRS)

A promising iron-base cast alloy is being developed as part of the DOE/NASA Stirling Engine Systems Project under contract DEN 3-282 with the United Technologies Research Center. This report presents the results of a study at the Lewis Research Center of the alloy's creep-rupture properties. The alloy was tested under a variety of conditions and was found to exhibit the normal 3-stage creep response. The alloy compared favorably with others being used or under consideration for the automotive Stirling engine cylinder/regenerator housing.

Titran, Robert H.; Scheuermann, Coulson M.

1987-01-01

138

A Winning Cast  

NASA Technical Reports Server (NTRS)

Howmet Research Corporation was the first to commercialize an innovative cast metal technology developed at Auburn University, Auburn, Alabama. With funding assistance from NASA's Marshall Space Flight Center, Auburn University's Solidification Design Center (a NASA Commercial Space Center), developed accurate nickel-based superalloy data for casting molten metals. Through a contract agreement, Howmet used the data to develop computer model predictions of molten metals and molding materials in cast metal manufacturing. Howmet Metal Mold (HMM), part of Howmet Corporation Specialty Products, of Whitehall, Michigan, utilizes metal molds to manufacture net shape castings in various alloys and amorphous metal (metallic glass). By implementing the thermophysical property data from by Auburn researchers, Howmet employs its newly developed computer model predictions to offer customers high-quality, low-cost, products with significantly improved mechanical properties. Components fabricated with this new process replace components originally made from forgings or billet. Compared with products manufactured through traditional casting methods, Howmet's computer-modeled castings come out on top.

2001-01-01

139

Formulation, Casting, and Evaluation of Paraffin-Based Solid Fuels Containing Energetic and Novel Additives for Hybrid Rockets  

NASA Technical Reports Server (NTRS)

This investigation studied the inclusion of various additives to paraffin wax for use in a hybrid rocket motor. Some of the paraffin-based fuels were doped with various percentages of LiAlH4 (up to 10%). Addition of LiAlH4 at 10% was found to increase regression rates between 7 - 10% over baseline paraffin through tests in a gaseous oxygen hybrid rocket motor. Mass burn rates for paraffin grains with 10% LiAlH4 were also higher than those of the baseline paraffin. RDX was also cast into a paraffin sample via a novel casting process which involved dissolving RDX into dimethylformamide (DMF) solvent and then drawing a vacuum on the mixture of paraffin and RDX/DMF in order to evaporate out the DMF. It was found that although all DMF was removed, the process was not conducive to generating small RDX particles. The slow boiling generated an inhomogeneous mixture of paraffin and RDX. It is likely that superheating the DMF to cause rapid boiling would likely reduce RDX particle sizes. In addition to paraffin/LiAlH4 grains, multi-walled carbon nanotubes (MWNT) were cast in paraffin for testing in a hybrid rocket motor, and assorted samples containing a range of MWNT percentages in paraffin were imaged using SEM. The fuel samples showed good distribution of MWNT in the paraffin matrix, but the MWNT were often agglomerated, indicating that a change to the sonication and mixing processes were required to achieve better uniformity and debundled MWNT. Fuel grains with MWNT fuel grains had slightly lower regression rate, likely due to the increased thermal conductivity to the fuel subsurface, reducing the burning surface temperature.

Larson, Daniel B.; Desain, John D.; Boyer, Eric; Wachs, Trevor; Kuo, Kenneth K.; Borduin, Russell; Koo, Joseph H.; Brady, Brian B.; Curtiss, Thomas J.; Story, George

2012-01-01

140

Development of CZTS-based thin film solar cells  

Microsoft Academic Search

The low cost, environmental harmless Cu2ZnSnS4 (CZTS)-based thin film solar cells are fabricated by using abundant materials. The CZTS film possesses promising characteristic optical properties; band-gap energy of about 1.5 eV and large absorption coefficient in the order of 104 cm?1. All constituents of this CZTS film, which are abundant in the crust of the earth, are non-toxic. Therefore, if we can

Hironori Katagiri; Kazuo Jimbo; Win Shwe Maw; Koichiro Oishi; Makoto Yamazaki; Hideaki Araki; Akiko Takeuchi

2009-01-01

141

Instant Casting Movie Theater: The Future Cast System  

NASA Astrophysics Data System (ADS)

We have developed a visual entertainment system called “Future Cast” which enables anyone to easily participate in a pre-recorded or pre-created film as an instant CG movie star. This system provides audiences with the amazing opportunity to join the cast of a movie in real-time. The Future Cast System can automatically perform all the processes required to make this possible, from capturing participants' facial characteristics to rendering them into the movie. Our system can also be applied to any movie created using the same production process. We conducted our first experimental trial demonstration of the Future Cast System at the Mitsui-Toshiba pavilion at the 2005 World Exposition in Aichi Japan.

Maejima, Akinobu; Wemler, Shuhei; Machida, Tamotsu; Takebayashi, Masao; Morishima, Shigeo

142

Optical medium based on vanadium oxide films  

NASA Astrophysics Data System (ADS)

The results of investigation of the optical properties of vanadium dioxide are reported. Thin VO2 films exhibited sharp and reversible optical switching due to the metal-insulator transition at T approximately equal to 70 degrees Celsius. The effect of laser irradiation on amorphous films of anodic vanadium oxide was also studied using a YAG Nd3+ laser at wavelengths of 1.06 and 0.53 micrometer. Modifications of the structure and physical properties are reported, and the application of such films for recording and storage of optical information is demonstrated.

Chudnovskii, F. A.; Pergament, A. L.; Schaefer, D. A.; Stefanovich, G. B.

1996-03-01

143

In situ FTIR and generalized 2D IR correlation spectroscopic studies on the crystallization behavior of solution-cast PHB film.  

PubMed

The crystallization behavior of biosynthesized poly(3-hydroxybutyrate) film cast from 1,1,2,2-tetrachloromethane was studied by in situ FTIR spectroscopy and two-dimensional (2D) correlation analysis. Time-dependent in situ FTIR spectral variations in the C=O stretching region (1,780-1,700 cm(-1)) were monitored and analyzed by a series of data processing methods, including calculation of difference spectrum and second derivative spectrum, Fourier self-deconvolution, curve-fitting and 2D correlation analysis. Four bands have been resolved from the 2D correlation analysis, and the following overall sequential order among the intensity changes of the four bands has been obtained at 1,750 > 1,739 > 1,722 > 1,715 cm(-1). Combining with the other data processing methods, a curve-fitting approach has been employed to reveal that there are probably five component bands under the C=O band profile, centered at 1,746; 1,737; 1,728; 1,722; and 1,712 cm(-1). Detailed analysis on the in situ component band intensity variations in the C=O stretching region indicates that the crystalline and amorphous band intensities change simultaneously during the crystallization process, with no local sequential order. Further analysis on the relative area percentage changes of the five component bands suggests that the crystalline component only changes in a fully cooperative manner with part of the amorphous component at the initial crystallization period. PMID:21336794

Huang, He; Guo, Wenjuan; Chen, Hong

2011-04-01

144

Mechanical properties and biodegradation characteristics of PHB-based films  

Microsoft Academic Search

An effect of plasticizers on physical properties and biodegradation characteristics of polyhydroxybutyrate (PHB) based films have been investigated. Laprol was a good plasticizer for PHB and for PHB containing biomass (BM) of Azotobacter chroococcum23. A maximum plasticizing effect was attained with a LAP concentration up to 30% w\\/w. The biodegradation rate of PHB and BM films significantly decreased with an

L Savenkova; Z Gercberga; V Nikolaeva; A Dzene; I Bibers; M Kalnin

2000-01-01

145

ANTIMICROBIAL EFFECTS ON STARCH-BASED FILMS INCORPORATED WITH LYSOZYMES  

Microsoft Academic Search

An antimicrobial (AM) Active Packaging can be made by incorporating and immobilizing suitable AM agents into food packages and applying a bio switch concept. A starch-based film was prepared and incorporated with antimicrobial agents, i.e. lysozyme and EDTA as chelating agent. This film was then inoculated with the bacteria Escherichia coli and Bacillus subtilis to carry out the microbial contamination

Nozieana Khairuddin; Ida Idayu Muhamad

146

Chimerical categories: caste, race, and genetics.  

PubMed

Is discrimination based on caste equivalent to racism? This paper explores the complex relationship between genetic, race and caste. It also discusses the debate over the exclusion of a discussion of caste-based discrimination at the 2001 World Conference against Racism, Racial Discrimination, Xenophobia and Related Intolerance held in Durban, South Africa. PMID:14768649

Sabir, Sharjeel

2003-12-01

147

Chitosan Based Film Electrolytes Doped Oleic Acid: An Electrical Study  

NASA Astrophysics Data System (ADS)

1g chitosan was dissolved in l00 mL of 1% acetic acid solution to prepare a chitosan acetate solution. The solution was then mixed with oleic acid. This chitosan acetate-oleic acid was then made into thin film by the solution cast technique. The conductivity of the samples was measured from ambient to elevated temperature. The highest conductivity of the chitosan-salt with 10 wt % oleic acid (OA) at room temperature was 8.35×10-9 Scm-1. The addition of OA has increased the dielectric constant, which implies the increase of dissociation of the salt thereby producing more free ions for conducting and hence increases the ionic conductivity.

Idris, Nor Kartini; Aziz, N. A. Nik; Ramli, S.; Isa, M. Ikmar Nizam

2008-05-01

148

Surface carburization of steel castings  

Microsoft Academic Search

Shaping methods based on sand-resin mixtures have undoubted benefits and accordingly are increas? ingly used in the manufacture of highperformance iron, steel, and nonferrousalloy castings. However, they cannot be unconditionally recommended for lowcarbon steel castings. This is because heat from the molten metal destroys the organic components present in such molds. At low temperatures (150 °C), these mixtures mainly emit

E. B. Ten; O. A. Kol’; I. B. Badmazhapova; M. P. Klyuev

2011-01-01

149

Development of Stronger and More Reliable Cast Austenitic Stainless Steels (H-Series) Based on Scientific Design Methodology  

SciTech Connect

The goal of this program was to increase the high-temperature strength of the H-Series of cast austenitic stainless steels by 50% and upper use temperature by 86 to 140 F (30 to 60 C). Meeting this goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The higher strength H-Series of cast stainless steels (HK and HP type) have applications for the production of ethylene in the chemical industry, for radiant burner tubes and transfer rolls for secondary processing of steel in the steel industry, and for many applications in the heat-treating industry. The project was led by Duraloy Technologies, Inc. with research participation by the Oak Ridge National Laboratory (ORNL) and industrial participation by a diverse group of companies. Energy Industries of Ohio (EIO) was also a partner in this project. Each team partner had well-defined roles. Duraloy Technologies led the team by identifying the base alloys that were to be improved from this research. Duraloy Technologies also provided an extensive creep data base on current alloys, provided creep-tested specimens of certain commercial alloys, and carried out centrifugal casting and component fabrication of newly designed alloys. Nucor Steel was the first partner company that installed the radiant burner tube assembly in their heat-treating furnace. Other steel companies participated in project review meetings and are currently working with Duraloy Technologies to obtain components of the new alloys. EIO is promoting the enhanced performance of the newly designed alloys to Ohio-based companies. The Timken Company is one of the Ohio companies being promoted by EIO. The project management and coordination plan is shown in Fig. 1.1. A related project at University of Texas-Arlington (UT-A) is described in Development of Semi-Stochastic Algorithm for Optimizing Alloy Composition of High-Temperature Austenitic Stainless Steels (H-Series) for Desired Mechanical and Corrosion Properties (ORNL/TM-2005/81/R1). The final report on another related project at the University of Tennessee by George Pharr, Easo George, and Michael Santella has been published as Development of Combinatorial Methods for Alloy Design and Optimization (ORNL/TM-2005-133). The goal of the project was to increase the high-temperature strength by 50% and upper use temperature by 86 to 140 F (30 to 60 C) of H-Series of cast austenitic stainless steels. Meeting such a goal is expected to result in energy savings of 38 trillion Btu/year by 2020 and energy cost savings of $185 million/year. The goal of the project was achieved by using the alloy design methods developed at ORNL, based on precise microcharacterization and identification of critical microstructure/properties relationships and combining them with the modern computational science-based tools that calculate phases, phase fractions, and phase compositions based on alloy compositions. The combined approach of microcharacterization of phases and computational phase prediction would permit rapid improvement of the current alloy composition of an alloy and provide the long-term benefit of customizing alloys within grades for specific applications. The project was appropriate for the domestic industry because the current H-Series alloys have reached their limits both in high-temperature-strength properties and in upper use temperature. The desire of Duraloy's industrial customers to improve process efficiency, while reducing cost, requires that the current alloys be taken to the next level of strength and that the upper use temperature limit be increased. This project addressed a specific topic from the subject call: to develop materials for manufacturing processes that will increase high-temperature strength, fatigue resistance, corrosion, and wear resistance. The outcome of the project would benefit manufacturing processes in the chemical, steel, and heat-treating industries.

Muralidharan, G.; Sikka, V.K.; Pankiw, R.I.

2006-04-15

150

Processing and characterization of extruded zein-based biodegradable films  

NASA Astrophysics Data System (ADS)

The objectives of this study were to prepare biodegradable zein films by extrusion processing and to evaluate relevant physical properties of resulting films with respect to their potential as packaging materials. The manufacture of protein-based packaging films by extrusion has remained a challenge. In this study, a zein resin was prepared by combining zein and oleic acid. This resin was formed into films by blown extrusion at the bench-top scale. Resin moisture content and extruder barrel temperature profile were identified as major parameters controlling the process. The optimum temperature of the blowing head was determined to be 40--45°C, while optimum moisture at film collection was 14--15%. Physico-chemical properties of the extruded products were characterized. Extruded products exhibited plastic behavior and ductility. Morphology characterization by SEM showed micro voids in extruded zein sheets, caused by entrapped air bubbles or water droplets. DSC characterization showed that zein was effectively plasticized by oleic acid as evidenced by the lowered glass transition temperature of zein films. X-ray scattering was used to investigate changes in zein molecular aggregation during processing. It was observed that higher mechanical energy treatment progressively disrupted zein molecular aggregates, resulting in a more uniform distribution of individual zein molecules. With the incorporation of oleic acid as plasticizer and monoglycerides as emulsifier, zein formed structures with long-range periodicity which varied depending on the formulation and processing methods. Processing methods for film formation affected the binding of oleic acid to zein with higher mechanical energy treatment resulting in better interaction between the two components. The moisture sorption capacity of extruded zein films was reduced due to the compact morphology caused by extrusion. Plasticization with oleic acid further reduced moisture sorption of zein films. The overall conclusion of this study is that blown film extrusion of zein-oleic acid resins is a promising process for the manufacture of zein films, resulting in films with potential for packaging applications.

Wang, Ying

151

Highly conductive, transparent flexible films based on open rings of multi-walled carbon nanotubes  

Microsoft Academic Search

Open rings of multi-walled carbon nanotubes were stacked to form porous networks on a poly(ethylene terephthalate) substrate to form a flexible conducting film (MWCNT-PET) with good electrical conductivity and transparency by a combination of ultrasonic atomization and spin-coating technique. To enhance the electric flexibility, we spin-coated a cast film of poly(vinyl alcohol) onto the MWCNT-PET substrate, which then underwent a

Wen-Yin Ko; Jun-Wei Su; Chian-Hua Guo; Shu-Juan Fu; Chuen-Yuan Hsu; Kuan-Jiuh Lin

2011-01-01

152

Chitosan and gelatin based edible films: state diagrams, mechanical and permeation properties  

Microsoft Academic Search

Films of chitosan and gelatin were prepared by casting their aqueous solutions (pH?4.0) at 60°C and evaporating at 22 or 60°C (low- and high-temperature methods, respectively). The physical (thermal, mechanical and gas\\/water permeation) properties of these composite films, plasticized with water or polyols, were studied. An increase in the total plasticizer content resulted in a considerable decrease of elasticity modulus

Ioannis S. Arvanitoyannis; Atsuyoshi Nakayama; Sei-ichi Aiba

1998-01-01

153

Abstract --This paper presents a knowledge-based approach to human-agent mixed teams for distributed team training in CAST-DDD.  

E-print Network

for distributed team training in CAST-DDD. CAST-DDD is a marriage between the multi-agent architecture CAST team as well as how agents reason about the dynamic, partially observable environment of the DDD for distributed team training in CAST-DDD. CAST-DDD is a marriage between the multi-agent architecture CAST [11

154

Anatase titanium dioxide thin film based carbon monoxide gas sensor  

NASA Astrophysics Data System (ADS)

Gas sensors are finding increasing number of applications in home, industrial and automotive areas. Incomplete combustion in gas and coal fired electricity plants can generate harmful gases and pollutants. The purpose of the proposed research was to develop titanium dioxide (TiO2) thin film based materials for carbon monoxide (CO) gas sensing to detect a very low concentration (20--100 ppm) of CO gas. Anatase TiO2 thin films (100--1000 nm) have been developed using pulsed DC magnetron reactive sputtering technique on glass, Si(100) and sapphire substrates. Optimum deposition parameters were determined by studying the crystalline quality of the films using X-ray diffraction. The x-ray photo-emission (XPS) studies indicated a good stoichiometric TiO 2 surface with O to Ti ratio of 1.95 +/- 0.05. Film residual stress was measured using curvature measurements of the substrates before and after deposition of the films. The anatase TiO2 thin films on sapphire showed lower stress compared to glass and Si substrates. Raman spectroscopy measurements were further used to study the correlation between the residual stress and Raman shifts of characteristic peaks to obtain a calibration factor. Anatase TiO2 thin films showed n-type electrical conductivity indicating the presence of shallow electron donors caused by oxygen vacancies. The response of films was tested for 100 ppm of CO in 100 sccm of N2 gas flow as a function of temperature, film thickness, and the substrate. The films show the highest response at 200°C. The films grown on sapphire substrates show the highest response. The response is higher for a film with 1000 nm thickness than the 250 nm thickness film. The CO sensor was tested as a function of CO concentration and as well as under different environs: The films respond to very low concentration, 20--100 ppm, of CO gas, with good reversibility. The response and recovery time were from 2 min to 1 min as the concentration increased from 20 to 100 ppm. It can be completely regenerated by turn off the CO gas without exposing it to oxygen or air. The sensor showed sensitivity for CO with as high as 2000 PPM of O2 concentration. It has the same response in dry and in humid environments. Furthermore, the anatase TiO2 thin film with no doping showed to have higher response than the doped films with Cu or La at 300°C.

Al-Homoudi, Ibrahim Abdullah

155

Porphyrin-based honeycomb films and their antibacterial activity.  

PubMed

Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields. PMID:24846091

Wang, Yanran; Liu, Yan; Li, Guihua; Hao, Jingcheng

2014-06-10

156

Casting methods  

DOEpatents

A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.

Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.

2012-12-18

157

Influence of SiO2 surface energy on the performance of organic field effect transistors based on highly oriented, zone-cast layers of a tetrathiafulvalene derivative  

NASA Astrophysics Data System (ADS)

In this paper we present that the surface energy of silicon dioxide employed as the dielectric in bottom gate organic field effect transistors has large impact on the device performance. By the use of the zone-casting simple solution processing technique, we ensured reproducibility of active layer preparation confirmed by the atomic force microscopy and x-ray diffraction that showed high crystalline quality. Electrical measurements revealed that charge carrier mobility based on highly ordered zone-cast tetrakis-(octadecylthio)-tetrathiafulvalene layer was increased 30 times to 0.2 cm2/V s, when dielectric surface energy decreased from 51.8 to 40.1 mN/m.

Miskiewicz, Pawel; Kotarba, Sylwia; Jung, Jaroslaw; Marszalek, Tomasz; Mas-Torrent, Marta; Gomar-Nadal, Elba; Amabilino, David B.; Rovira, Concepcio; Veciana, Jaume; Maniukiewicz, Waldemar; Ulanski, Jacek

2008-09-01

158

Gating of Permanent Molds for ALuminum Casting  

SciTech Connect

This report summarizes a two-year project, DE-FC07-01ID13983 that concerns the gating of aluminum castings in permanent molds. The main goal of the project is to improve the quality of aluminum castings produced in permanent molds. The approach taken was determine how the vertical type gating systems used for permanent mold castings can be designed to fill the mold cavity with a minimum of damage to the quality of the resulting casting. It is evident that somewhat different systems are preferred for different shapes and sizes of aluminum castings. The main problems caused by improper gating are entrained aluminum oxide films and entrapped gas. The project highlights the characteristic features of gating systems used in permanent mold aluminum foundries and recommends gating procedures designed to avoid common defects. The study also provides direct evidence on the filling pattern and heat flow behavior in permanent mold castings.

David Schwam; John F. Wallace; Tom Engle; Qingming Chang

2004-03-30

159

Effect of gamma radiation on the mechanical and barrier properties of HEMA grafted chitosan-based films  

NASA Astrophysics Data System (ADS)

Chitosan films were prepared by dissolving 1% (w/v) chitosan powder in 2% (w/v) aqueous acetic acid solution. Chitosan films were prepared by solution casting. The values of puncture strength (PS), viscoelasticity coefficient and water vapor permeability (WVP) of the films were found to be 565 N/mm, 35%, and 3.30 g mm/m2 day kPa, respectively. Chitosan solution was exposed to gamma irradiation (0.1-5 kGy) and it was revealed that PS values were reduced significantly (p?0.05) after 1 kGy dose and it was not possible to form films after 5 kGy. Monomer, 2-hydroxyethyl methacrylate (HEMA) solution (0.1-1%, w/v) was incorporated into the chitosan solution and the formulation was exposed to gamma irradiation (0.3 kGy). A 0.1% (w/v) HEMA concentration at 0.3 kGy dose was found optimal-based on PS values for chitosan grafting. Then radiation dose (0.1-5 kGy) was optimized for HEMA grafting. The highest PS values (672 N/mm) were found at 0.7 kGy. The WVP of the grafted films improved significantly (p?0.05) with the rise of radiation dose.

Khan, Avik; Huq, Tanzina; Khan, Ruhul A.; Dussault, Dominic; Salmieri, Stephane; Lacroix, Monique

2012-08-01

160

Energy Consumption of Die Casting Operations  

SciTech Connect

Molten metal processing is inherently energy intensive and roughly 25% of the cost of die-cast products can be traced to some form of energy consumption [1]. The obvious major energy requirements are for melting and holding molten alloy in preparation for casting. The proper selection and maintenance of melting and holding equipment are clearly important factors in minimizing energy consumption in die-casting operations [2]. In addition to energy consumption, furnace selection also influences metal loss due to oxidation, metal quality, and maintenance requirements. Other important factors influencing energy consumption in a die-casting facility include geographic location, alloy(s) cast, starting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting form of alloy (solid or liquid), overall process flow, casting yield, scrap rate, cycle times, number of shifts per day, days of operation per month, type and size of die-casting machine, related equipment (robots, trim presses), and downstream processing (machining, plating, assembly, etc.). Each of these factors also may influence the casting quality and productivity of a die-casting enterprise. In a die-casting enterprise, decisions regarding these issues are made frequently and are based on a large number of factors. Therefore, it is not surprising that energy consumption can vary significantly from one die-casting enterprise to the next, and within a single enterprise as function of time.

Jerald Brevick; clark Mount-Campbell; Carroll Mobley

2004-03-15

161

Hot-Wire Deposition of Hydrogenated Nanocrystalline SiGe Films for Thin-Film Si Based Solar Cells  

E-print Network

Hot-Wire Deposition of Hydrogenated Nanocrystalline SiGe Films for Thin-Film Si Based Solar Cells investigations of nc-SiGe:H thin films made by hot-wire chemical vapor deposition (HWCVD) with a coil in an a-Si based multiple- junction solar cell. 1. INTRODUCTION Narrow bandgap amorphous SiGe (a-Si

Deng, Xunming

162

Electroslag component casting. [Nickel aluminide  

SciTech Connect

This project is directed toward the development of electroslag-casting (ESC) technology for use in coal conversion components such as valve bodies, pump housings, and pipe fittings. The aim is also to develop a sufficient data base to permit electroslag casting to become an ASME Code-accepted process. It is also intended to transfer the ESC process technology to private industry. A total of 32 electroslag castings of 2.25Cr-1Mo, 9Cr-1Mo, type 316, and nickel aluminide were procured from four facilities for evaluation (Table 1). The most complex castings procured during this program were the valve bodies shown in Figure 2. The castings were subjected to various heat treatments (Table 2), checked for chemical composition uniformity from top to bottom, and subjected to macrostructural evaluation and mechanical properties testing. Results are discussed. 10 refs., 7 figs., 3 tabs.

Sikka, V.K.

1986-01-01

163

Thin-film glucose biosensor based on plasma-polymerized film: simple design for mass production.  

PubMed

We propose a simple thin-film glucose biosensor based on a plasma-polymerized film. The film is deposited directly onto the substrate under dry conditions. The resulting films are extreme thin, adhere well onto the substrate (electrode), and have a highly cross-linked network structure and functional groups, such as amino groups, which enable a large amount of enzyme to be immobilized. Since this design allows fabrication through a dry process, with the exception of the enzyme immobilization, which is the last stage of the process, the chip fabrication can be designed as a full-wafer process to achieve mass production compatibility. The resulting sensors produced using this film are more reproducible, exhibit lower noise, and reduce the effect of interference to a greater degree than sensors made using conventional immobilization methods, e.g., via 3-(aminopropyl)triethoxysilane. The obtained film is a good interfacial design between enzyme and electrode; enzyme two-dimensionally locates very close to the electrode in a manner that is quite reproducible. Therefore, a wide dynamic range (up to 60 mM) and rapid response time (11.5+/-0.8 s) were obtained. Because of its highly cross-linking network structure, the amperometric response due to interferences such as ascorbic acid and acetaminophen was reduced by size discrimination of plasma-polymerized films. PMID:10857654

Muguruma, H; Hiratsuka, A; Karube, I

2000-06-01

164

Directional solidification of large cross-section nickel-base superalloy castings via liquid-metal cooling  

NASA Astrophysics Data System (ADS)

The drive for higher efficiency in very large industrial gas turbines (IGTs) used in power generation applications has led to the need for directional solidification of large cross-section components, such as turbine blades, used in the hot gas path sections of the IGTs. The Bridgman directional solidification technique, which is currently used to produce these components, has been optimized for much smaller aero-engine components. The scale-up of this technique to produce large parts has resulted in numerous problems, and consequently low casting yield, which can all be related to the limited cooling capability of the Bridgman process. In this dissertation, a higher cooling efficiency process, liquid-metal cooling (LMC) using Sn as the cooling medium, has been evaluated for improved capability to cast large cross-section components. A series of castings were made for direct comparison using both the conventional Bridgman and the high thermal gradient LMC processes. Casting conditions were selected to simulate the state of the art for the Bridgman method and to assess the limits of casting with the less familiar LMC method. The experiments were evaluated through thermocouple analyses of casting conditions and post-casting analyses of grain defects, microstructural features, and mechanical behavior. Additionally, a finite element model of the solidification process was developed to further elucidate casting conditions. The casting parameters and elements of the LMC process that had the greatest influence on casting conditions were determined. Results indicated that the LMC process is capable of significantly enhancing cooling efficiency during directional solidification of large cross-section components. The enhanced cooling allowed much faster solidification withdrawal rates and resulted in substantially refined cast microstructure. The LMC process eliminated freckle-type defects in all cases and considerably reduced other casting defects under optimal conditions. It also was determined that the location of the solidification front during the LMC process is a crucial parameter that must be controlled to produce a high quality casting. Additionally, a floating thermal baffle used with the LMC-Sn process was established as an indispensable element of the LMC process.

Elliott, Andrew J.

165

As-cast uranium-molybdenum based metallic fuel candidates and the effects of carbon addition  

NASA Astrophysics Data System (ADS)

The objective of this research was to develop and recommend a metallic nuclear fuel candidate that lowered the onset temperature of gamma phase formation comparable or better than the uranium-10 wt. pct. molybdenum alloy, offered a solidus temperature as high or higher than uranium-10 wt. pct. zirconium (1250°C), and stabilized the fuel phase against interaction with iron and steel at least as much as uranium-10 wt. pct. zirconium stabilized the fuel phase. Two new as-cast alloy compositions were characterized to assess thermal equilibrium boundaries of the gamma phase field and the effect of carbon addition up to 0.22 wt. pct. The first system investigated was uranium- x wt. pct. M where x ranged between 5-20 wt. pct. M was held at a constant ratio of 50 wt. pct. molybdenum, 43 wt. pct. titanium, and 7 wt. pct. zirconium. The second system investigated was the uranium-molybdenum-tungsten system in the range 90 wt. pct. uranium - 10 wt. pct. molybdenum - 0 wt. pct. tungsten to 80 wt. pct. uranium - 10 wt. pct. molybdenum - 10 wt. pct. tungsten. The results showed that the solidus temperature increased with increased addition of M up to 12.5 wt. pct. for the uranium-M system. Alloy additions of titanium and zirconium were removed from uranium-molybdenum solid solution by carbide formation and segregation. The uranium-molybdenum-tungsten system solidus temperature increased to 1218°C at 2.5 wt. pct. with no significant change in temperature up to 5 wt. pct. tungsten suggesting the solubility limit of tungsten had been reached. Carbides were observed with surrounding areas enriched in both molybdenum and tungsten. The peak solidus temperatures for the alloy systems were roughly the same at 1226°C for the uranium-M system and 1218°C for the uranium-molybdenum-tungsten system. The uranium-molybdenum-tungsten system required less alloy addition to achieve similar solidus temperatures as the uranium-M system.

Blackwood, Van Stephen

166

BaPbO3-based thick film resistor  

Microsoft Academic Search

A thick-film resistor system that does not use a rare-earth or a transitional element was fabricated with semi-metallic BaPbO3 and alkali glass powders. Its characteristics are comparable to conventional thick-film resistors such as those in the RuO2-based system, while the cost is much lower. The relationship between glass-frit content and sheet resistivity is approximated by an exponential equation, and an

Yu-Hung Hsieh; Shen-Li Fu

1992-01-01

167

Texture based prelens tear film segmentation in interferometry images  

Microsoft Academic Search

Interferometric imaging has been identified as a novel approach to the evaluation of prelens tear film (PLTF) thickness in\\u000a contact lens patients. In this paper, we present a texture based segmentation approach for the detection of tear film breakup\\u000a regions on interferometry images. First, the textural information was extracted from the studied images using a bank of Gabor\\u000a filters. A

Dijia Wu; Kim L. Boyer; Jason J. Nichols; Peter E. King-Smith

2010-01-01

168

Gas sensors based on nanoparticle WO3 thick films  

Microsoft Academic Search

The gas sensing properties of chemical sensors based on nanoparticle WO3 thick films, doped with indium and bismuth, are studied. Commercial WO3 nanopowder with spherical diameter up to 33.1 nm was mixed with either InCl3 or BiCl3. The sensing films of the sensors were prepared using three different concentrations of each doping metal (1.5 wt.%, 3.0 wt.% and 5.0 wt.%,

V. Khatko; R. Ionescu; E. Llobet; X. Vilanova; J. Brezmes; J. Hubalek; K. Malysz; X. Correig

2004-01-01

169

Superhydrophobic cellulose-based bionanocomposite films from Pickering emulsions  

NASA Astrophysics Data System (ADS)

Inherently superhydrophobic and flexible cellulose-based bionanocomposites were fabricated from solid stabilized (Pickering) emulsions. Emulsions were formed by dispersing cyclosiloxanes in water stabilized by layered silicate particles and were subsequently modified by blending into a zinc oxide nanofluid. The polymer matrix was a blend of cellulose nitrate and fluoroacrylic polymer (Zonyl 8740) precompatibilized in solution. Coatings were spray cast onto aluminum substrates from polymer blends dispersed in modified Pickering emulsions. No postsurface treatment was required to induce superhydrophobicity. Effect of antiseptic additives on bionanocomposite superhydrophobicity is also discussed. Replacing cellulose nitrate with commercial liquid bandage solutions produced identical superhydrophobic coatings.

Bayer, Ilker S.; Steele, Adam; Martorana, Philip J.; Loth, Eric; Miller, Lance

2009-04-01

170

Optimization of Gating System Design for Die Casting of Thin Magnesium Alloy-Based Multi-Cavity LCD Housings  

NASA Astrophysics Data System (ADS)

High-pressure die casting is the preferred process for manufacturing Mg-alloy components used for numerous applications. High-pressure die casting is suitable for mass production and has the advantage of also being suitable for accurately fashioning objects of complicated shapes. One disadvantage of high-speed die casting is the occurrence of defects such as shrinkage or air entrainment. Gating system design must be very effective in actual manufacturing facilities to avoid the occurrence of such defects. The objective of this study is to present a methodology for obtaining optimal designs of 4-cavity thin electronic component housings. The fluid behavior and amount of air entrainment caused by the overflows and air vent designs were analyzed using a computer fluid dynamics (CFD) simulator. The effectiveness of the proposed system was demonstrated through CFD simulations and experiments using an actual manufacturing process. Also, the effect of vacuum systems on the porosity and mechanical properties of the castings was studied. The volume of porosity in the casting was found to be significantly reduced using vacuum assistance during die casting. As a result, the tensile strength and the elongation of the die casting products are improved.

Lee, B. D.; Baek, U. H.; Han, J. W.

2012-09-01

171

Clamshell Casting! Stefanie Wuhrer  

E-print Network

Clamshell Casting! By Stefanie Wuhrer A thesis submitted to the Faculty of Graduate Studies and Research acceptance of the thesis, Clamshell Casting! submitted by Stefanie Wuhrer Douglas Howe (Director is casting, where liquid is poured into a cast and the cast is removed once the liquid has hardened. We

Wuhrer, Stefanie

172

Steel castings by the electroslag casting technique  

NASA Astrophysics Data System (ADS)

Electroslag casting facilities in Canada and the United States were reviewed. Several value body castings of 2 1/4 Cr-1 Mo, 9 Cr-1 Mo, and 18% Cr-8% Ni (Mo) steels were made at the University of British Columbia facility. These castings were examined for surface finish, chemical segregation, and macrostructure in the as-cast condition and after various heat treatments. Castings were subjected to tensile, charpy impact, and creep testing. Results of these tests were compared with similar data on wrought material and where applicable, with data on sand castings.

Sikka, V. K.; Mitchell, A.

1984-10-01

173

Steel castings by the electroslag casting technique  

SciTech Connect

Electroslag casting facilities in Canada and the United States were reviewed. Several valve body castings of 2 1/4 Cr-1 Mo, 9 Cr-1 Mo, and 18% Cr-8% Ni(Mo) steels were made at the University of British Columbia facility. These castings were examined for surface finish, chemical segregation, and macrostructure in the as-cast condition and after various heat treatments. Castings were subjected to tensile, Charpy impact, and creep testing. Results of these tests were compared with similar data on wrought material and, where applicable, with data on sand castings. 22 figures.

Sikka, V.K.; Mitchell, A.

1984-10-01

174

Resin Vacuum Casting System for LED Screen  

Microsoft Academic Search

This paper mainly describes the resin vacuum casting system for LED screen which uses thin film degassing technology and meter mix technology. Thin film degassing technology is currently the most effective method. In this paper, we describe in detail its working model. And meter mix dispensing technology integrates metering pump and mixing pump. It mixes materials according to the demand.

Hong Robin; Wang Hongmei; Hu Ming

2010-01-01

175

SUBTLEX-ESP: Spanish Word Frequencies Based on Film Subtitles  

ERIC Educational Resources Information Center

Recent studies have shown that word frequency estimates obtained from films and television subtitles are better to predict performance in word recognition experiments than the traditional word frequency estimates based on books and newspapers. In this study, we present a subtitle-based word frequency list for Spanish, one of the most widely spoken…

Cuetos, Fernando; Glez-Nosti, Maria; Barbon, Analia; Brysbaert, Marc

2011-01-01

176

Bioelectronic imaging array based on bacteriorhodopsin film.  

PubMed

A photoreceptor array that exploits the light sensitive bacteriorhodopsin (bR) films has been manufactured on a flexible indium-tin-oxide (ITO) coated plastic film using electrophoretic sedimentation technique (EPS). The effective sensing area of each photoreceptor is 2 x 2 mm (2), separated by 1 mm and arranged in a 4 x 4 array. A switched integrator with gain on the order of 10(10) is used to amplify the signal to a suitable level. When exposed to light, the differential response characteristic is attributed to charge displacement and recombination within bR molecules, as well as loading effects of the attached amplifier. The peak spectral response occurs at 568 nm and is linear over the tested light power range of 200 mu W to 12 mW. The response remains linear at other tested wavelengths, but with reduced amplitude. Initial tests have indicated that responsivity among all photoreceptors is greater than 71% of the average value, 465.25 mV/mW. The differential nature of the signal generated by bR makes it a suitable sensing material for vision applications such as motion detection. The prototype array demonstrates this property by employing Reichardt's delay-and-correlate algorithm. Furthermore, fabricating sensor arrays on flexible substrates introduces a new design approach that enables non-planar imaging surfaces. PMID:19203868

Wang, Wei Wei; Knopf, George K; Bassi, Amarjeet S

2008-12-01

177

Slip-Cast Superconductive Parts  

NASA Technical Reports Server (NTRS)

Complex shapes fabricated without machining. Nonaqueous slip-casting technique used to form complexly shaped parts from high-temperature superconductive materials like YBa(2)Cu(3)O(7-delta). Such parts useful in motors, vibration dampers, and bearings. In process, organic solvent used as liquid medium. Ceramic molds made by lost-wax process used instead of plaster-of-paris molds, used in aqueous slip-casting but impervious to organic solvents and cannot drain away liquid medium. Organic-solvent-based castings do not stick to ceramic molds as they do to plaster molds.

Wise, Stephanie A.; Buckley, John D.; Vasquez, Peter; Buck, Gregory M.; Hicks, Lana P.; Hooker, Matthew W.; Taylor, Theodore D.

1993-01-01

178

Effects of composition and testing conditions on oxidation behavior of four cast commercial nickel-base superalloys  

NASA Technical Reports Server (NTRS)

Four cast nickel-base superalloys were oxidized at 1000 and 1100 C for times up to 100 hr in static air and a Mach 1 gas stream. The oxidation resistance was judged by weight change, metal thickness loss, depletion-zone formation, and oxide formation and morphology. The alloys which formed mostly nickel aluminate (NiAl2O4) and aluminum oxide (Al2O3) (B-1900, VIA, and to a lesser extent 713C) were more oxidation resistant. Poorer oxidation resistance was associated with the appearance of chromium sesquioxide (Cr2O3) and chromite spinel (738X). Refractory metal content had little effect on oxidation resistance. Refractory metals appeared in the scale as tapiolite (NiM2O6, where M represents the refractory metal). Thermal cycling in static air appeared to supply sufficient data for the evaluation of oxidation resistance, especially for alloys which form oxides of low volatility. For alloys of higher chromium levels with high propensities toward forming a chromium-bearing scale of higher volatility, testing under conditions of high gas velocity is necessary to assess fully the behavior of the alloy.

Lowell, C. E.; Probst, H. B.

1974-01-01

179

Preparation and Mechanical Characterization of Gelatin-Based Films Using 2-Hydroxyethyl Methacrylate Cured by UV Radiation  

Microsoft Academic Search

Gelatin films were prepared from gelatin granules in aqueous medium by casting. Tensile strength, tensile modulus and elongation at break of the gelatin films were found to be 27 MPa, 100 MPa and 4%, respectively. Gelatin films were soaked in five different formulations containing 2-hydroxyethyl methacrylate (HEMA) (10–50%, by wt), methanol and photoinitiator and then cured under UV radiation. Again, a series

Sabrina Sultana; Ruhul A. Khan; Mubarak A. Khan; Haydar U. Zaman; Parvin Banu; M. Nuruzzaman Khan; A. I. Mustafa

2010-01-01

180

Piezotronic Effect on ZnO Nanowire Film Based Temperature Sensor Limin Zhang,,  

E-print Network

Piezotronic Effect on ZnO Nanowire Film Based Temperature Sensor Fei Xue,,§ Limin Zhang,,§ Wei Tang ZnO nanowire (NW) film. The film was synthesized by the wet chemical deposition method, the traditional thin- film based processing is quite mature, which has been used successfully in semiconductor

Wang, Zhong L.

181

Compression-Based Ray Casting of Very Large Volume Data in Distributed Environments  

E-print Network

imaging (MRI), and color cryosection images of male and female human cadavers in an effort to offer a com compression, attempts to enhance the rendering speedups by quickly reconstructing voxel data from local memory rather than expensively fetching them from remote memory spaces. Our compression-based volume render- ing

Texas at Austin, University of

182

Photon heterostructures based on single-crystal opal films  

Microsoft Academic Search

Creation of photon film crystals based on opal structures is a very urgent problem being investigated by several research teams in Russia, Europe, and the United States. We develop an original approach for solving this problem [1?3] on the basis on the properties of nanocrystallization in suspensions of monodisperse spherical silica particles (MSSPs) [4?8]. There are two different methods for

D. V. Kalinin; A. I. Plekhanov; V. V. Serdobintseva; V. F. Shabanov

2007-01-01

183

Prediction of Part Distortion in Die Casting  

SciTech Connect

The die casting process is one of the net shape manufacturing techniques and is widely used to produce high production castings with tight tolerances for many industries. An understanding of the stress distribution and the deformation pattern of parts produced by die casting will result in less deviation from the part design specification, a better die design and eventually more productivity and cost savings. This report presents methods that can be used to simulate the die casting process in order to predict the deformation and stresses in the produced part and assesses the degree to which distortion modeling is practical for die casting at the current time. A coupled thermal-mechanical finite elements model was used to simulate the die casting process. The simulation models the effect of thermal and mechanical interaction between the casting and the die. It also includes the temperature dependant material properties of the casting. Based on a designed experiment, a sensitivity analysis was conducted on the model to investigate the effect of key factors. These factors include the casting material model, material properties and thermal interaction between casting and dies. To verify the casting distortion predictions, it was compared against the measured dimensions of produced parts. The comparison included dimensions along and across the parting plane and the flatness of one surface.

R. Allen Miller

2005-03-30

184

A casting based process to fabricate 3D alginate scaffolds and to investigate the influence of heat transfer on pore architecture during fabrication  

Microsoft Academic Search

The fabrication of 3-dimensional (3D) tissue scaffolds is a competitive approach to engineered tissues. An ideal tissue scaffold must be highly porous, biocompatible, biodegradable, easily processed and cost-effective, and have adequate mechanical properties. A casting based process has been developed in this study to fabricate 3D alginate tissue scaffolds. The alginate\\/calcium gluconate hydrogel was quenched in a glass mold and

W. M. Parks; Y. B. Guo

2008-01-01

185

The effects of Cr, Al, Ti, Mo, W, Ta, and Cb on the cyclic oxidation behavior of cast Ni-base superalloys at 1100 and 1150°C  

Microsoft Academic Search

A series of cast nickel-base y\\/y' superalloys as systematically varied at two nonzero levels of Cr, Al, Ti, Mo, Cb, W, and Ta with nominally fixed levels of 10 at. % Co, 0.06 at. % C, 0.05 at. % Zr, and 0.05% B. A 1\\/4-replicate 27-factorial statistical design supplemented by 18 additional alloys was used to estimate main effects and

C. A. Barrett; R. V. Miner; D. R. Hull

1983-01-01

186

Ultrathin calix(n)arene-based Langmuir-Blodgett films for gas separations  

NASA Astrophysics Data System (ADS)

Gas separation composite membranes consisting of ultrathin amphiphilic calix[n]arene (C[n]A) monolayers deposited on highly permeable poly[1-(trimethylsilyl)-1-propyne] (PTMSP) support were fabricated and characterized. A series of calix[n]arene-based surfactants was studied, which consisted of various number of units in the macrocycle (e.g., n = 4, 5 and 6), hydrophilic head groups on the "upper-rim" [e.g., amidoxime (AO), boronic acid and acetyl (MK) head groups] and alkyl chains on the "lower rim" [e.g., n-octyl, n-dodecyl (C12) and n-hexadecyl ( C16) tails]. For purposes of comparison, conventional surfactants such as arachidic acid, stearoamidoxime (SA), heptadecylboronic acid and poly(1-octadecene-co-maleic anhydride) (POM) were also investigated. The surfactants were characterized by determining their monolayer properties at the air-water interface, which included surface pressure-area isotherm and surface viscosity behavior. Composite membranes were fabricated using Langmuir-Blodgett (LB) and self-assembly methods and characterized by He and N2 gas permeation properties, X-ray photoelectron spectroscopy, FTIR spectroscopy, ellipsometry, goniometry and electronic imaging. Composites consisting of LB monolayers of amphiphilic calix[n]arene, polymeric and single straight-chain surfactants on PTMSP cast film exhibit significant, modest and no increases in permeation selectivity as compared to the parent support, respectively; e.g., composites consisting of four LB monolayers of C16C[6]AAO, C12C[6]AAO, C16C[6]AMK, POM and SA on PTMSP and bare PTMSP exhibit He/N2 selectivities of ca. 200, 100, 24, 5, 0.9 and 0.9, respectively. Evidence for the causes of these dramatic differences in properties are reported and discussed. It has been found that important criteria for forming highly gas selective surfactant films include: (1) the individual surfactants must be large enough to span the individual holes of the support and (2) strong intermolecular forces between neighboring calix[n]arenes (e.g., via H-bonding and hydrophobic interactions) are necessary to form tightly-packed and robust LB films. The implications of these results, in terms of the further development of LB films as membranes for gas separations and comparisons between industrial membrane materials are discussed. A LB film of C16C[6]AAO represents the "world's thinnest" membrane separator, achieving high He/N2 selectivity.

Hendel, Robert Ashley

187

Thick-film humidity sensor based on porous ? material  

Microsoft Academic Search

A new compact, robust, yet fast and highly sensitive ceramic humidity sensor based on the semiconducting metal oxide 0957-0233\\/8\\/6\\/002\\/img2 has been developed using thick-film technology. The sensor element possesses a novel `sandwich' configuration with a 0957-0233\\/8\\/6\\/002\\/img3 porous 0957-0233\\/8\\/6\\/002\\/img2 ceramic layer sandwiched by two 0957-0233\\/8\\/6\\/002\\/img5 polarity-reversed interdigitated metal films. Instead of traditional glass frits, LiCl powders were used as adhesion promoters.

Wenmin Qu; Jörg-Uwe Meyer

1997-01-01

188

A tunable hybrid metamaterial absorber based on vanadium oxide films  

NASA Astrophysics Data System (ADS)

A tunable hybrid metamaterial absorber (MA) in the microwave band was designed, fabricated and characterized. The hybrid MA was realized by incorporating a VO2 film into the conventional resonant MA. By thermally triggering the insulator-metal phase transition of the VO2 film, the impedance match condition was broken and a deep amplitude modulation of about 63.3% to the electromagnetic wave absorption was achieved. A moderate blue-shift of the resonance frequency was observed which is promising for practical applications. This VO2-based MA exhibits many advantages such as strong tunability, frequency agility, simple fabrication and ease of scaling to the terahertz band.

Wen, Qi-Ye; Zhang, Huai-Wu; Yang, Qing-Hui; Chen, Zhi; Long, Yang; Jing, Yu-Lan; Lin, Yuan; Zhang, Pei-Xin

2012-06-01

189

Thin Wall Iron Castings  

SciTech Connect

Results of an investigation made to develop methods of making iron castings having wall thicknesses as small as 2.5 mm in green sand molds are presented. It was found that thin wall ductile and compacted graphite iron castings can be made and have properties consistent with heavier castings. Green sand molding variables that affect casting dimensions were also identified.

J.F. Cuttino; D.M. Stefanescu; T.S. Piwonka

2001-10-31

190

LLNL casting technology  

Microsoft Academic Search

Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting

A. B. Shapiro; W. J. Comfort III

1994-01-01

191

Film formation on silver-based switching contacts  

Microsoft Academic Search

The reactions of atmospheric pollutants with silver-based switching contact materials produce corrosion products which can adversely affect the contact's electrical behavior. In the present study, three silver-based contact materials-Ag\\/Cu\\/Ni, Ag\\/Ni, and Ag\\/MgO\\/NiO-were exposed to an accelerated corrosion environment containing SO2, H2S, NO2, and Cl2 . An elevated temperature and high humidity were also maintained. Both electrical degradation and corrosion film

Steven J. Simko; Anthony Lee; S. W. Gaarenstroom; Audrey A. DOW; Curtis A. Wong

1989-01-01

192

Vertical Conducting Nanodomains Self-Assembled from Poly(3-hexylthiophene)-Based Diblock Copolymer Thin Films  

SciTech Connect

We have synthesized {pi}-conjugated poly(3-hexyl thiophene)-block-poly(methyl methacrylate) (P3HT-b-PMMA) with a P3HT molecular weight of 11 kDa and a PMMA volume fraction of 0.53, which potentially has several organic electronic applications. Its phase-separation behavior was investigated for various thicknesses cast from organic solvents. When cast onto 300 nm thick SiO{sub 2} dielectrics from toluene, in which the P3HT segments have limited solubility, the P3HT-b-PMMA films consist of nanofibrillar self-assemblies of laterally {pi}-stacked P3HT chains. In contrast, the P3HT segments were found to be highly mobile in chlorobenzene, generating a typical phase-separation morphology consisting of vertically conducting P3HT nanodomains on these dielectrics. As the thickness of the cast films increased, however, the topmost surface becomes covered with {pi}-conjugated nanofibrils that are laterally oriented with respect to the surface. Due to the anisotropic domain orientations of P3HT, top-gate organic field-effect transistors (OFETs) containing the P3HT-b-PMMA films exhibited enhanced electrical performance compared to bottom-gate OFETs.

Y Lee; S Kim; H Yang; M Jang; S Hwang; H Lee; K Baek

2011-12-31

193

Filmless versus film-based systems in radiographic examination costs: an activity-based costing method  

PubMed Central

Background Since the shift from a radiographic film-based system to that of a filmless system, the change in radiographic examination costs and costs structure have been undetermined. The activity-based costing (ABC) method measures the cost and performance of activities, resources, and cost objects. The purpose of this study is to identify the cost structure of a radiographic examination comparing a filmless system to that of a film-based system using the ABC method. Methods We calculated the costs of radiographic examinations for both a filmless and a film-based system, and assessed the costs or cost components by simulating radiographic examinations in a health clinic. The cost objects of the radiographic examinations included lumbar (six views), knee (three views), wrist (two views), and other. Indirect costs were allocated to cost objects using the ABC method. Results The costs of a radiographic examination using a filmless system are as follows: lumbar 2,085 yen; knee 1,599 yen; wrist 1,165 yen; and other 1,641 yen. The costs for a film-based system are: lumbar 3,407 yen; knee 2,257 yen; wrist 1,602 yen; and other 2,521 yen. The primary activities were "calling patient," "explanation of scan," "take photographs," and "aftercare" for both filmless and film-based systems. The cost of these activities cost represented 36.0% of the total cost for a filmless system and 23.6% of a film-based system. Conclusions The costs of radiographic examinations using a filmless system and a film-based system were calculated using the ABC method. Our results provide clear evidence that the filmless system is more effective than the film-based system in providing greater value services directly to patients. PMID:21961846

2011-01-01

194

Thin film porous membranes based on sol-gel chemistry for catalytic sensors  

Microsoft Academic Search

Nanoporous sol-gel based films are finding a wide variety of uses including gas separations and supports for heterogeneous catalysts. The films can be formed by spin or dip coating, followed by relatively low temperature annealing. The authors used several types of these films as coatings on the Pd alloy thin film sensors they had previously fabricated and studied. The sol-gel

R. C. Hughes; S. V. Patel; M. W. Jenkins; T. J. Boyle; T. J. Gardner; C. J. Brinker

1998-01-01

195

Antistaphylococcal Nanocomposite Films Based on Enzyme-Nanotube Conjugates  

PubMed Central

Infection with antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is one of the primary causes of hospitalizations and deaths. To address this issue, we have designed antimicrobial coatings incorporating carbon nanotube-enzyme conjugates that are highly effective against antibiotic–resistant pathogens. Specifically, we incorporated conjugates of carbon nanotubes with lysostaphin, a cell wall degrading enzyme, into films to impart bactericidal properties against Staphylococcus aureus and Staphylococcus epidermidis. We fabricated and characterized nanocomposites containing different conjugate formulations and enzyme loadings. These enzyme–based composites were highly efficient in killing MRSA (>99% within 2 h) without release of the enzyme into solution. Additionally, these films were reusable and stable under dry storage conditions for a month. Such enzyme–based film formulations may be used to prevent growth of pathogenic and antibiotic-resistant microorganisms on various common surfaces in hospital settings. Polymer and paint films containing such antimicrobial conjugates, in particular, could be advantageous to prevent risk of staphylococcal-specific infection and biofouling. PMID:20604574

Pangule, Ravindra C.; Brooks, Sarah J.; Dinu, Cerasela Zoica; Bale, Shyam Sundhar; Salmon, Sharon L.; Zhu, Guangyu; Metzger, Dennis W.; Kane, Ravi S.; Dordick, Jonathan S.

2010-01-01

196

Antistaphylococcal nanocomposite films based on enzyme-nanotube conjugates.  

PubMed

Infection with antibiotic-resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) is one of the primary causes of hospitalizations and deaths. To address this issue, we have designed antimicrobial coatings incorporating carbon nanotube-enzyme conjugates that are highly effective against antibiotic-resistant pathogens. Specifically, we incorporated conjugates of carbon nanotubes with lysostaphin, a cell wall degrading enzyme, into films to impart bactericidal properties against Staphylococcus aureus and Staphylococcus epidermidis. We fabricated and characterized nanocomposites containing different conjugate formulations and enzyme loadings. These enzyme-based composites were highly efficient in killing MRSA (>99% within 2 h) without release of the enzyme into solution. Additionally, these films were reusable and stable under dry storage conditions for a month. Such enzyme-based film formulations may be used to prevent growth of pathogenic and antibiotic-resistant microorganisms on various common surfaces in hospital settings. Polymer and paint films containing such antimicrobial conjugates, in particular, could be advantageous to prevent risk of staphylococcal-specific infection and biofouling. PMID:20604574

Pangule, Ravindra C; Brooks, Sarah J; Dinu, Cerasela Zoica; Bale, Shyam Sundhar; Salmon, Sharon L; Zhu, Guangyu; Metzger, Dennis W; Kane, Ravi S; Dordick, Jonathan S

2010-07-27

197

10B thin film based position sensitive neutron detector  

NASA Astrophysics Data System (ADS)

With the global crisis of He3, it is essential to explore the use of other alternatives as BF3 and boron coated detectors, particularly for neutron scattering applications. Performance of BF3 filled position sensitive detectors (PSD) is evaluated, mentioned elsewhere and novel designs are being tried for gain in efficiency. Whereas performance of boron film based detectors for use as PSD is being presently evaluated. Though efficiency of 10B film detector in equivalent dimensions is lower than that with BF3, main advantage of 10B film detectors is its non-toxic nature. A boron film based PSD in coaxial geometry is developed with 10B (90%enriched) coating thickness of 1 mg/cm2 on inner lining of cathode. Detailed characterization of a PSD is essential for further designs of large area PSD. Present PSD is evaluated for the pulse height, plateau characteristics, uniformity of coating thickness and position resolution. The position resolution improves with higher gas pressure, whereas multiple layers are essential to gain efficiency. Results from these characterizations of the PSD are presented.

Desai, Shraddha S.; Devan, Shylaja

2013-02-01

198

Simulation-based selection of optimum pressure die-casting process parameters using neural nets and genetic algorithms  

Microsoft Academic Search

Pressure die-casting condition selection mainly relies on the experience and expertise of individuals working in production industries. Systematic knowledge accumulation regarding the manufacturing process is essential in order to obtain optimal process conditions. It is not safe a priori to presume that rules of thumb, which are widely used on the shop floor, always lead to fast prototype production calibration

A. Krimpenis; P. G. Benardos; G.-C. Vosniakos; A. Koukouvitaki

2006-01-01

199

Metal casting extended assessments  

SciTech Connect

In 1997, the Industrial Assessment Center program of the US Department of Energy initiated Extended Assessments as an option for some of their in-plant assessments. Intended for larger, more complex manufacturing facilities, the multi-day Extended Assessment allows the plant assessment team to explore more complex recommendations with the intent of encouraging major process and equipment changes. In this paper the authors describe the results of Extended Assessments at plants in the Metal Casting Industry, one of the DOE Industries of the Future. They visited five plants, two foundries and three die casting plants, with combined annual sales of $134 million and a combined annual production volume of 35,300 tons. The recommendations offered potential savings to each plant of an average $417,000 or 1.5% of average gross sales. A number of generalizations can be observed based on the assessments in the cast metals industry. First is that many of the smaller firms in this industry have been slow to adopt innovative technology. Off the shelf technologies are available that will help these firms reach the 21st Century. The concept of remelt of metal or scrap in the plant is an operation that can be improved. They found approximately two pounds of metal melted for every pound shipped. Finally, many opportunities exist outside of the core plant operations to reduce operating costs.

Ambs, L.; Kosanovic, D.; Muller, M.; Kasten, D.

1999-07-01

200

Preparation and Characterization of Modified Cellulose Fiber-Reinforced Polyvinyl Alcohol\\/Polypyrrolidone Hybrid Film Composites  

Microsoft Academic Search

In this work, cellulose was modified by using 2-(trifluromethyl)benzoylchloride by base catalyzed reaction. Modification of cellulose was confirmed by IR studies. The biodegradable composite films were developed by a film casting method using modified cellulose with poly(vinyl alcohol) and polypyrrolidone in different compositions. Film composites showed good biodegradability. Better barrier and mechanical properties showed by film composites as the percentage

Sandeep S. Laxmeshwar; S. Viveka; D. J. Madhu Kumar; Dinesha; R. F. Bhajanthri; G. K. Nagaraja

2012-01-01

201

Homogeneous bilayer graphene film based flexible transparent conductor  

NASA Astrophysics Data System (ADS)

Graphene is considered as a promising candidate to replace conventional transparent conductors due to its low opacity, high carrier mobility and flexible structure. Multi-layer graphene or stacked single layer graphenes have been investigated in the past but both have their drawbacks. The uniformity of multi-layer graphene is still questionable, and single layer graphene stacks require many transfer processes to achieve sufficiently low sheet resistance. In this work, bilayer graphene film grown with low pressure chemical vapor deposition was used as a transparent conductor for the first time. The technique was demonstrated to be highly efficient in fabricating a conductive and uniform transparent conductor compared to multi-layer or single layer graphene. Four transfers of bilayer graphene yielded a transparent conducting film with a sheet resistance of 180 ?? at a transmittance of 83%. In addition, bilayer graphene films transferred onto the plastic substrate showed remarkable robustness against bending, with sheet resistance change less than 15% at 2.14% strain, a 20-fold improvement over commercial indium oxide films.Graphene is considered as a promising candidate to replace conventional transparent conductors due to its low opacity, high carrier mobility and flexible structure. Multi-layer graphene or stacked single layer graphenes have been investigated in the past but both have their drawbacks. The uniformity of multi-layer graphene is still questionable, and single layer graphene stacks require many transfer processes to achieve sufficiently low sheet resistance. In this work, bilayer graphene film grown with low pressure chemical vapor deposition was used as a transparent conductor for the first time. The technique was demonstrated to be highly efficient in fabricating a conductive and uniform transparent conductor compared to multi-layer or single layer graphene. Four transfers of bilayer graphene yielded a transparent conducting film with a sheet resistance of 180 ?? at a transmittance of 83%. In addition, bilayer graphene films transferred onto the plastic substrate showed remarkable robustness against bending, with sheet resistance change less than 15% at 2.14% strain, a 20-fold improvement over commercial indium oxide films. Electronic supplementary information (ESI) available: Preparation of bilayer graphene based transparent conductor, multilayer graphene synthesis, Raman spectroscopy, transmittance measurement, and sheet resistance measurement. See DOI: 10.1039/c1nr11574j

Lee, Seunghyun; Lee, Kyunghoon; Liu, Chang-Hua; Zhong, Zhaohui

2012-01-01

202

Usefulness of gel-casting method in the fabrication of nonstoichiometric CaZrO{sub 3}-based electrolytes for high temperature application  

SciTech Connect

Hydrogels obtained from lower toxicity monomers of N-(hydroxymethyl)acrylamide and N,N'-methylenebisacrylamide were applied to form nonstoichiometric CaZrO{sub 3}-based electrolytes. A coprecipitation-calcination method with ((NH{sub 4}){sub 2}C{sub 2}O{sub 4}) in concentrated NH{sub 3} aqueous solution was used to synthesise CaZrO{sub 3} involving 51 mol.% CaO (CZ-51) powder. The gas-tight CaZrO{sub 3}-based rods were prepared by the gel-casting method with 45 vol.% suspension and then sintered at 1500 deg. C-2 h. It was found that in low oxygen partial pressure, the nonstoichiometric CaZrO{sub 3} obtained by gel-casting method were pure oxide ion conductors. These samples exhibited comparable electrical conductivity values to isostatically compressed pellets starting from the same powder. The results of experiments on thermochemical stability of CZ-51 gel-cast shapes at high temperatures in air or gas mixtures involving 2-50 vol.% H{sub 2}, as well as the corrosion resistance in exhaust gases from a self-ignition engine were also presented and discussed. The thermal resistance of CaZrO{sub 3} obtained rods against molten nickel or iron was also examined. Based upon these investigations, it is evident that only in hydrogen-rich gas atmospheres can the stability of CaZrO{sub 3} shapes be limited due to the presence of CaO precipitation as a second phase. The nonstoichiometric CaZrO{sub 3} (CZ-51) gel-cast materials were also tested in solid galvanic cells, designed to study thermodynamic properties of oxide materials, important for SOFC and energy technology devices. In this way, the Gibbs energy of NiM{sub 2}O{sub 4}, M = Cr, Fe, at 650-1000 deg. C was determined. The CaZrO{sub 3} involving 51 mol.% CaO gel-cast sintered shapes seems to be promising solid electrolytes for electrochemical oxygen probes in control of metal processing and thermodynamic studies of materials important for the development of the energy industry.

Dudek, Magdalena [AGH - University of Science and Technology, Faculty of Energy and Fuels, 30-059 Cracow (Poland)

2009-09-15

203

Effects of the Exposure to Corrosive Salts on the Frictional Behavior of Gray Cast Iron and a Titanium-Based Metal Matrix Composite  

SciTech Connect

The introduction of increasingly aggressive road-deicing chemicals has created significant and costly corrosion problems for the trucking industry. From a tribological perspective, corrosion of the sliding surfaces of brakes after exposure to road salts can create oxide scales on the surfaces that affect friction. This paper describes experiments on the effects of exposure to sodium chloride and magnesium chloride sprays on the transient frictional behavior of cast iron and a titanium-based composite sliding against a commercial brake lining material. Corrosion scales on cast iron initially act as abrasive third-bodies, then they become crushed, spread out, and behave as a solid lubricant. The composition and subsurface microstructures of the corrosion products on the cast iron were analyzed. Owing to its greater corrosion resistance, the titanium composite remained scale-free and its frictional response was markedly different. No corrosion scales were formed on the titanium composite after aggressive exposure to salts; however, a reduction in friction was still observed. Unlike the crystalline sodium chloride deposits that tended to remain dry, hygroscopic magnesium chloride deposits absorbed ambient moisture from the air, liquefied, and retained a persistent lubricating effect on the titanium surfaces.

Blau, Peter Julian [ORNL; Truhan, Jr., John J [ORNL; Kenik, Edward A [ORNL

2007-01-01

204

Arabinoxylan-lipid-based edible films and coatings. 3. Influence of drying temperature on film structure and functional properties.  

PubMed

This work is a contribution to better knowledge of the influence of the structure of films obtained from emulsions based on arabinoxylans, hydrogenated palm kernel oil, and emulsifiers on their functional properties. The sucrose esters (emulsifiers) have a great effect on the stabilization of the emulsified film structure containing arabinoxylans and hydrogenated palm kernel oil. The structure and stability of the emulsion during drying strongly affect barrier and mechanical properties of films. The higher are creaming and coalescence phenomena in films, the lower is the water vapor permeability. Emulsion destabilization is favored by high drying temperature and tends to give films having a "bilayer-like" structure, which tends to improve the functional properties of arabinoxylans-based edible films. PMID:11929307

Phan The, D; Debeaufort, F; Péroval, C; Despré, D; Courthaudon, J L; Voilley, A

2002-04-10

205

Biomimetic membrane arrays on cast hydrogel supports.  

PubMed

Lipid bilayers are intrinsically fragile and require mechanical support in technical applications based on biomimetic membranes. Tethering the lipid bilayer membranes to solid substrates, either directly through covalent or ionic substrate-lipid links or indirectly on substrate-supported cushions, provides mechanical support but at the cost of small molecule transport through the membrane-support sandwich. To stabilize biomimetic membranes while allowing transport through a membrane-support sandwich, we have investigated the feasibility of using an ethylene tetrafluoroethylene (ETFE)/hydrogel sandwich as the support. The sandwich is realized as a perforated surface-treated ETFE film onto which a hydrogel composite support structure is cast. We report a simple method to prepare arrays of lipid bilayer membranes with low intrinsic electrical conductance on the highly permeable, self-supporting ETFE/hydrogel sandwiches. We demonstrate how the ETFE/hydrogel sandwich support promotes rapid self-thinning of lipid bilayers suitable for hosting membrane-spanning proteins. PMID:21526805

Roerdink Lander, Monique; Ibragimova, Sania; Rein, Christian; Vogel, Jörg; Stibius, Karin; Geschke, Oliver; Perry, Mark; Hélix-Nielsen, Claus

2011-06-01

206

Usefulness of gel-casting method in the fabrication of nonstoichiometric CaZrO 3-based electrolytes for high temperature application  

Microsoft Academic Search

Hydrogels obtained from lower toxicity monomers of N-(hydroxymethyl)acrylamide and N,N?-methylenebisacrylamide were applied to form nonstoichiometric CaZrO3-based electrolytes. A coprecipitation-calcination method with ((NH4)2C2O4) in concentrated NH3 aqueous solution was used to synthesise CaZrO3 involving 51mol.% CaO (CZ-51) powder. The gas-tight CaZrO3-based rods were prepared by the gel-casting method with 45vol.% suspension and then sintered at 1500°C–2h. It was found that in

Magdalena Dudek

2009-01-01

207

High-performance sensors based on molybdenum disulfide thin films.  

PubMed

High-performance sensors based on molybdenum disulfide (MoS2 ) grown by sulfurization of sputtered molybdenum layers are presented. Using a simple integration scheme, it is found that the electrical conductivity of MoS2 films is highly sensitive to NH3 adsorption, consistent with n-type semiconducting behavior. A sensitivity of 300 ppb at room temperature is achieved, showing the high potential of 2D transition metal-dichalcogenides for sensing. PMID:24027114

Lee, Kangho; Gatensby, Riley; McEvoy, Niall; Hallam, Toby; Duesberg, Georg S

2013-12-10

208

All-optical logic-gates based on bacteriorhodopsin film  

NASA Astrophysics Data System (ADS)

Based on self-diffraction in bacteriorhodopsin (bR) film, we propose all-optical NOT, XOR, half adder and XNOR logic operations. Using the relation between diffraction light and the polarization states of recording beams, we demonstrate NOT and XNOR logic operations. Studying the relation of polarization states among the diffracting, recording and reading beams, we implement XOR logic and half adder operations with three inputs. The methods are simple and practicable.

Chen, Gui-Ying; Zhang, Chun-Ping; Guo, Zong-Xia; Tian, Jian-Guo; Zhang, Guang-Yin; Song, Qi-Wang

2005-04-01

209

Tribological properties of transfer films of PTFE-based composites  

Microsoft Academic Search

PTFE-based composites containing 15vol.% MoS2, graphite, aluminum and bronze powder, were respectively prepared by compression molding at room temperature and subsequent heat treatment in atmosphere. Transfer films of pure PTFE and these composites were prepared on the surface of AISI-1045 steel bar using a friction and wear tester in a pin on disk contacting configuration. Tribological properties of these transfer

Yunxia Wang; Fengyuan Yan

2006-01-01

210

Team-based thin-film CIS research activities  

SciTech Connect

This paper describes the team-based thin-film copper indium diselenide (CIS) research activities. The CIS team was formed in December 1994 in Kona, Hawaii. Originally, the team had two working groups: the {open_quotes}Junction{close_quotes} and the {open_quotes}Absorber{close_quotes} groups. Currently, there are four working groups the Present Junction, New Junction, Substrate/Mo Impact, and the Transient Effect groups. We have completed extensive data compilation of CIS-based films and solar cells using various techniques such as Auger, photoluminescence, scanning electron microscopy, secondary-ion mass spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction, capacitance-voltage, light and dark current-voltage, and quantum efficiency. Studies are under way to understand the fundamental mechanisms that demonstrate a total-area, high efficiency of 17.7{percent} in CuInGaSe{sub 2} devices using chemical-bath deposition (CBD) CdS. Alternate buffer layers are also being investigated to replace the CBD CdS. The impact of various Mo substrates from the various industrial partners has been investigated, and the results are reported. A study is under way to investigate the transient effects in encapsulated/laminated thin-film CIS-based devices. {copyright} {ital 1997 American Institute of Physics.}

Ullal, H.S. [National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401 (United States)

1997-02-01

211

Comparative Evaluation of Marginal Accuracy of a Cast Fixed Partial Denture Compared to Soldered Fixed Partial Denture Made of Two Different Base Metal Alloys and Casting Techniques: An In vitro Study.  

PubMed

The periodontal health of abutment teeth and the durability of fixed partial denture depends on the marginal adaptation of the prosthesis. Any discrepancy in the marginal area leads to dissolution of luting agent and plaque accumulation. This study was done with the aim of evaluating the accuracy of marginal fit of four unit crown and bridge made up of Ni-Cr and Cr-Co alloys under induction and centrifugal casting. They were compared to cast fixed partial denture (FPD) and soldered FPD. For the purpose of this study a metal model was fabricated. A total of 40 samples (4-unit crown and bridge) were prepared in which 20 Cr-Co samples and 20 Ni-Cr samples were fabricated. Within these 20 samples of each group 10 samples were prepared by induction casting technique and other 10 samples with centrifugal casting technique. The cast FPD samples obtained were seated on the model and the samples were then measured with travelling microscope having precision of 0.001 cm. Sectioning of samples was done between the two pontics and measurements were made, then the soldering was made with torch soldering unit. The marginal discrepancy of soldered samples was measured and all findings were statistically analysed. The results revealed minimal marginal discrepancy with Cr-Co samples when compared to Ni-Cr samples done under induction casting technique. When compared to cast FPD samples, the soldered group showed reduced marginal discrepancy. PMID:24605006

Jei, J Brintha; Mohan, Jayashree

2014-03-01

212

Slip Casting of ?-Sialon/AlN/BN Powder Carbothermally Prepared by Boron-rich Slag-based Mixture  

NASA Astrophysics Data System (ADS)

With boron-rich slag, silica fume, bauxite chalmette and carbon black as starting materials, ?-Sialon/AlN/BN powder was prepared by carbothermal reduction-nitridation. The powder was attrition milled to submicron size and suspended in water. The effects of yttrium oxide as a sintering aid, pH, and addition of deflocculant on the suspensions were study. Optimum slip casting properties, i.e. lowest viscosity values, the highest absolute zeta potential values, the smallest floc size and sediment volume were found at pH 10 for the powder. The suspensions were used to slip cast discs which were sintered in a nitrogen atmosphere at 1700°C for 2h. The strength was about 230MPa, the toughness 3.6 MPa·m1/2 and the hardness about 13.8GPa.

Jun-bin, Wu; Xiang-xin, Xue; Tao, Jiang; Qing, Zhang

2011-10-01

213

An electron metallographic study of pressure die-cast commercial zinc–aluminium-based alloy ZA27  

Microsoft Academic Search

The microstructure of ZA27 pressure die-castings was examined by scanning and transmission electron microscopy after ageing\\u000a for 5 years at ambient temperatures. Solidification began with the formation of compact aluminium-rich ?? dendrites and tiny\\u000a rounded ?? particles, followed by the peritectic reaction whereby a zinc-rich ? phase formed around the edges of the primary\\u000a phases. The extremely high cooling rate

M. DURMAN; S. MURPHY

1997-01-01

214

4E-6 Electric Field Sensitivity of Thin Film Resonators Based on Piezoelectric AlN Thin Films  

Microsoft Academic Search

Thin film bulk acoustic wave resonators (FBAR), solidly mounted resonators (SMR), and thin film plate acoustic resonators (FPAR) based on piezoelectric aluminum nitride (AlN) are all attractive candidates for monolithically integrated filters, sensors and oscillators operating in the gigahertz frequency range. This work aims at performing a systematic study of the DC electric field sensitivity of FBAR, SMR and FPAR

J. Enlund; V. Yantchev; I. Katardjiev

2006-01-01

215

Edible films made from gelatin, soluble starch and polyols, Part 3  

Microsoft Academic Search

The thermal and mechanical properties of edible films based on blends of gelatin with soluble starch plasticized with water, glycerol or sugars were investigated. Two different methods, known as ‘the high temperature’ and ‘the low temperature’ methods, consisting of casting aqueous solutions of blends at 60 and 20 °C, respectively, were employed for the preparation of films. With increasing water,

I. Arvanitoyannis; E. Psomiadou; A. Nakayama; S. Aiba; N. Yamamoto

1997-01-01

216

LLNL casting technology  

NASA Astrophysics Data System (ADS)

Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US competiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

Shapiro, A. B.; Comfort, W. J., III

1994-01-01

217

LLNL casting technology  

SciTech Connect

Competition to produce cast parts of higher quality, lower rejection rate, and lower cost is a fundamental factor in the global economy. To gain an edge on foreign competitors, the US casting industry must cut manufacturing costs and reduce the time from design to market. Casting research and development (R&D) are the key to increasing US compentiveness in the casting arena. Lawrence Livermore National Laboratory (LLNL) is the home of a wide range of R&D projects that push the boundaries of state-of-the art casting. LLNL casting expertise and technology include: casting modeling research and development, including numerical simulation of fluid flow, heat transfer, reaction/solidification kinetics, and part distortion with residual stresses; special facilities to cast toxic material; extensive experience casting metals and nonmetals; advanced measurement and instrumentation systems. Department of Energy (DOE) funding provides the leverage for LLNL to collaborate with industrial partners to share this advanced casting expertise and technology. At the same time, collaboration with industrial partners provides LLNL technologists with broader insights into casting industry issues, casting process data, and the collective, experience of industry experts. Casting R&D is also an excellent example of dual-use technology; it is the cornerstone for increasing US industrial competitiveness and minimizing waste nuclear material in weapon component production. Annual funding for casting projects at LLNL is $10M, which represents 1% of the total LLNL budget. Metal casting accounts for about 80% of the funding. Funding is nearly equally divided between development directed toward US industrial competitiveness and weapon component casting.

Shapiro, A.B.; Comfort, W.J. III [eds.

1994-01-01

218

Synthesis, characterization and antibacterial activity of biodegradable films prepared from Schiff bases of zein.  

PubMed

Pure zein is known to be very hydrophobic, but is still inappropriate for coating and film applications because of their brittle nature. In an attempt to improve the flexibility and the antimicrobial activity of these coatings and films, Chemical modification of zein through forming Schiff bases with different phenolic aldhydes was tried. Influence of this modifications on mechanical, topographical, wetting properties and antimicrobial activity of zein films were evaluated. The chemical structure of the Schiff bases films were characterized by ATR-FTIR spectroscopy. The results indicate an improvement in mechanical properties with chemically modification of zein to form Schiff bases leading to a reduction in the elastic modulus. An increase in the elongation at break has been observed, but with slight influence on tensile strength. Plasticized zein films have similar initial contact angle (?40°). An increase in reaction temperature and time increases film's affinity towards water. As shown by contact angle measurements, a noticeable relation was found between film composition and the hydrophilicity. Surface topography also varied by forming Schiff bases, becoming rougher than zein-based films. The antibacterial activities of zein and Schiff bases of zein-based films were investigated against gram-positive bacteria (Listeria innocua, Listeria monocytogenes, Bacillus cereus and Clostridium sporogenes) and gram-negative bacteria (Escherichia coli, Yersinia enterocolitica and Salmonella enterica). It was found that the antibacterial activity of the Schiff bases-based films was more effective than that of zein-based films. PMID:25328181

Soliman, E A; Khalil, A A; Deraz, S F; El-Fawal, G; Elrahman, S Abd

2014-10-01

219

Egyptian Caste System  

NSDL National Science Digital Library

Understand the culture, character, and societal characteristics of different classes in the ancient Egyptian caste system Understand the culture, character, and societal characteristics of different classes in the ancient Egyptian caste system Go to these sites to learn about the Egyptian Caste System ...

Issen, Ms.

2009-09-17

220

OF INVESTMENT CASTS ALLOYS  

Microsoft Academic Search

Deformation and cracking of cast parts due to thermal stresses and hindered shrinkage are fre- quent casting defects. Whereas the numerical simulation of mold filling and solidification are already state of the art, applications of a thermal stress analysis are rarely found. The present study reveals how a combined thermo-mechanical model can be used for the investment casting process by

L. C. Würker; M. Fackeldey; P. R. Sahm; B. G. Thomas

221

Casting and Molding  

NSDL National Science Digital Library

This activity was designed for blind learners, but all types of learners can explore the process used to cast and mold molten metal, glass, and plastics. Using gelatin, the learner will work with a variety of molds to create castings. When the shapes are unmolded, the learner can tactually explore the casts.

Blind, Perkins S.

2012-06-26

222

Simultaneous Modification of Bottom-Contact Electrode and Dielectric Surfaces for Organic Thin-Film Transistors Through Single-Component Spin-Cast Monolayers  

SciTech Connect

An efficient process is developed by spin-coating a single-component, self-assembled monolayer (SAM) to simultaneously modify the bottom-contact electrode and dielectric surfaces of organic thin-film transistors (OTFTs). This efficient interface modification is achieved using n-alkyl phosphonic acid based SAMs to prime silver bottom-contacts and hafnium oxide (HfO{sub 2}) dielectrics in low-voltage OTFTs. Surface characterization using near edge X-ray absorption fine structure (NEXAFS) spectroscopy, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, atomic force microscopy (AFM), and spectroscopic ellipsometry suggest this process yields structurally well-defined phosphonate SAMs on both metal and oxide surfaces. Rational selection of the alkyl length of the SAM leads to greatly enhanced performance for both n-channel (C60) and p-channel (pentacene) based OTFTs. Specifically, SAMs of n-octylphos-phonic acid (OPA) provide both low-contact resistance at the bottom-contact electrodes and excellent interfacial properties for compact semiconductor grain growth with high carrier mobilities. OTFTs based on OPA modifi ed silver electrode/HfO{sub 2} dielectric bottom-contact structures can be operated using < 3V with low contact resistance (down to 700 Ohm-cm), low subthreshold swing (as low as 75 mV dec{sup -1}), high on/off current ratios of 107, and charge carrier mobilities as high as 4.6 and 0.8 cm{sup 2} V{sup -1} s{sup -1}, for C60 and pentacene, respectively. These results demonstrate that this is a simple and efficient process for improving the performance of bottom-contact OTFTs.

O Acton; M Dubey; t Weidner; K OMalley; T Kim; G Ting; D Hutchins; J Baio; T Lovejoy; et al.

2011-12-31

223

Low cycle fatigue life of two nickel-base casting alloys in a hydrogen environment. [for high-pressure oxidizer turbopump turbine nozzles  

NASA Technical Reports Server (NTRS)

Samples of two nickel-base casting alloys, Mar-M-246 (a Martin Company alloy) and 713LC (a low-carbon modification of the alloy 713C developed by International Nickel Company) were tested as candidate materials for the high-pressure fuel and high-pressure oxidizer turbopump turbine nozzles. The samples were subjected to tensile tests and to low cycle fatigue tests in high-pressure hydrogen to study the influence of the hydrogen environment. The Mar-M-246 material was found to have a three times higher cyclic life in hydrogen than the 713LC alloy, and was selected as the nozzle material.

Cooper, R. A.

1976-01-01

224

Yield Improvement in Steel Casting (Yield II)  

SciTech Connect

This report presents work conducted on the following main projects tasks undertaken in the Yield Improvement in Steel Casting research program: Improvement of Conventional Feeding and Risering Methods, Use of Unconventional Yield Improvement Techniques, and Case Studies in Yield Improvement. Casting trials were conducted and then simulated using the precise casting conditions as recorded by the participating SFSA foundries. These results present a statistically meaningful set of experimental data on soundness versus feeding length. Comparisons between these casting trials and casting trials performed more than forty years ago by Pellini and the SFSA are quite good and appear reasonable. Comparisons between the current SFSA feeding rules and feeding rules based on the minimum Niyama criterion reveal that the Niyama-based rules are generally less conservative. The niyama-based rules also agree better with both the trials presented here, and the casting trails performed by Pellini an d the SFSA years ago. Furthermore, the use of the Niyama criterion to predict centerline shrinkage for horizontally fed plate sections has a theoretical basis according to the casting literature reviewed here. These results strongly support the use of improved feeding rules for horizontal plate sections based on the Niyama criterion, which can be tailored to the casting conditions for a given alloy and to a desired level of soundness. The reliability and repeatability of ASTM shrinkage x-ray ratings was investigated in a statistical study performed on 128 x-rays, each of which were rated seven different times. A manual ''Feeding and Risering Guidelines for Steel Castings' is given in this final report. Results of casting trials performed to test unconventional techniques for improving casting yield are presented. These use a stacked arrangement of castings and riser pressurization to increase the casting yield. Riser pressurization was demonstrated to feed a casting up to four time s the distance of a non-pressurized riser, and can increase casting yield by decreasing the required number of risers. All case studies for this projects were completed and compiled into an SFSA Technical Report that is submitted part of this Final Report

Richard A. Hardin; Christoph Beckermann; Tim Hays

2002-02-18

225

Development of Advanced Coating Techniques for Highly-durable Casting Dies  

NASA Astrophysics Data System (ADS)

In order to improve the durability of aluminum die-casting molds, we applied microstructure-controlled PVD coating techniques. Single-layer and multilayer films consisting of chromium nitride (CrN) or titanium aluminum nitride (TiAlN) were prepared using an ion plating process. Structures of multilayer films were observed using transmission electron microscopy. Pin-shaped mold steel specimens coated with each of the films were soaked in the molten aluminum alloy at 953 K different periods of time, and the amount of weight loss due to erosion was evaluated. The weight losses for the multilayer CrN and TiAlN specimens were found to be less than those for the single-layer specimens. As a practical test, five specimens of core pins used in aluminum die casting of automobile parts were coated with multilayer films, and the number of maintenance operations required to remove aluminum alloy remaining on the specimen surfaces after several thousand castings was counted and compared with six control specimens (core pins treated using a commercial salt bath diffusion process). The number of maintenance operations for CrN- and TiAlN-based multilayer-coated core pins was found to be lower than for the control specimens.

Tanaka, S.; Takagi, M.; Mano, T.

2013-03-01

226

Solution-cast films of poly(3,4-ethylenedioxythiophene) as ion-to-electron transducers in all-solid-state ion-selective electrodes  

Microsoft Academic Search

An aqueous dispersion of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(styrenesulfonate) (PSS) was cast on screen-printed gold substrates. PEDOT(PSS) was ionically (physically) crosslinked by multivalent cations, including Mg2+, Ca2+, Fe2+\\/3+ and Ru(NH3)62+\\/3+ to form a hydrogel in order to decrease the water solubility of the PEDOT(PSS). The resulting Au\\/PEDOT(PSS) electrodes were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and energy-dispersive

Mercedes Vázquez; Petter Danielsson; Johan Bobacka; Andrzej Lewenstam; Ari Ivaska

2004-01-01

227

A comparison of mechanical properties of all-ceramic alumina dental crowns prepared from aqueous- and non-aqueous-based tape casting.  

PubMed

Alumina-glass dental composites were prepared by aqueous- and non-aqueous-based tape casting and sintering at 1120 degrees C, followed by glass infiltration at 1100 degrees C. Flexural strength and fracture toughness of the composites were investigated in terms of influence of tape constituents, namely, alumina powder, binder, and plasticizer on the mechanical properties. For the alumina-glass composites prepared from the aqueous-based tapes, both strength and toughness increased with increasing alumina fraction ratio in tape constituents including organic substances, a/a+o, and binder content ratio in binder/binder + plasticizer mixture, b/b+p. For the composites prepared from the non-aqueous-based tapes, on the other hand, both strength and toughness increased with increasing the a/a+o ratio but decreased with increasing the b/b+p ratio. These observations were consistent with influence of the constituents on mean alumina particle distance in tapes, suggesting that high strength of the glass infiltrated alumina composites is related to toughening by crack bowing. The optimized strength of the aqueous and nonaqueous tape cast composites was 559 and 508 MPa, and the fracture toughness was 3.3 and 3.1 MPam(1/2), respectively. PMID:10898872

Kim, D J; Lee, M H; Lee, D Y; Han, J S

2000-01-01

228

Tantalum-based thin film coatings for wear resistant arthroprostheses.  

PubMed

Cobalt-chromium-molybdenum alloys with high carbon content (HC-CoCrMo) are widely used as materials for arthroprosthesis, in particular in metal-on-metal (MoM) hip joints. In spite of their good wear and corrosion resistance, production of metallic wear particles and metal ion release will occur on a large time-scale. An enhancement of the metal ion level in the patient's blood and urine is often reported in clinical data. Hypersensitivity, inflammatory response and cell necrosis can occur as consequence. So implants on young patients and women on childbearing age are not so widespread. The aim of this research is the realization of a thin film coating in order to improve the biocompatibility of Co-based alloys and to reduce debris production, ion release and citotoxicity. The innovative process consists of a thermal treatment in molten salts, in order to obtain a tantalum enriched thin film coating. Tantalum is chosen because it is considered a biocompatible metal with high corrosion resistance and low ion release. Three HC-CoCrMo alloys, produced by different manufacturing processes, are tested as substrates. The coating is a thin film of TaC or it can be composed by a multilayer of two tantalum carbides and metallic tantalum, depending on the temperature of the treatment and on the carbon content of the substrate. The thin films as well the substrates are characterized from the structural, chemical and morphological point of view. Moreover mechanical behaviour of treated and untreated materials is analyzed by means of nanohardness, scratch and ball-on-disc wear tests. The coating increases the mechanical and tribological properties of HC-CoCrMo. PMID:22400292

Balagna, C; Faga, M G; Spriano, S

2011-10-01

229

Magnesium-lithium casting alloys  

NASA Technical Reports Server (NTRS)

The strength properties of magnesium-lithium alloys at room, low, and high temperatures are investigated. It is found that the alloys may have practical application at ambient temperatures up to 100 C, that negative temperatures have a favorable influence on the alloy strength, and that cyclic temperature variations have practically no effect on the strength characteristics. The influence of chemical coatings on corrosion resistance of the MgLi alloys is examined. Several facilities based on pressure casting machines, low-pressure casting machines, and magnetodynamic pumps were designed for producing MgLi alloy castings. Results were obtained for MgLi alloys reinforced with fibers having a volumetric content of 15%.

Latenko, V. P.; Silchenko, T. V.; Tikhonov, V. A.; Maltsev, V. P.; Korablin, V. P.

1974-01-01

230

Functional properties and antifungal activity of films based on gliadins containing cinnamaldehyde and natamycin.  

PubMed

Gliadin films cross-linked with cinnamaldehyde (1.5, 3, and 5%) and incorporated with natamycin (0.5%) were prepared by casting, and their antifungal activity, water resistance, and barrier properties were characterized. Incorporation of natamycin gave rise to films with greater water uptake, weight loss and diameter gain, and higher water vapor and oxygen permeabilities. These results may be associated to a looser packing of the protein chains as a consequence of the presence of natamycin. The different cross-linking degree of the matrices influenced the natamycin migration to the agar test media, increasing from 13.3 to 23.7 (?g/g of film) as the percentage of cinnamaldehyde was reduced from 5% to 1.5%. Antifungal activity of films was assayed against common food spoilage fungi (Penicillium species, Alternaria solani, Colletotrichum acutatum). The greatest effectiveness was obtained for films containing natamycin and treated with 5% of cinnamaldehyde. The level of cinnamaldehyde reached in the head-space of the test assay showed a diminishing trend as a function of time, which was in agreement with fungal growth and cinnamaldehyde metabolization. Developed active films were used in the packaging of cheese slices showing promising results for their application in active packaging against food spoilage. PMID:24412960

Balaguer, Mari Pau; Fajardo, Paula; Gartner, Hunter; Gomez-Estaca, Joaquin; Gavara, Rafael; Almenar, Eva; Hernandez-Munoz, Pilar

2014-03-01

231

Effects of Vanadium Doping on Resistive Switching Characteristics and Mechanisms of Based Memory Films  

Microsoft Academic Search

The effects of vanadium doping on resistive switching (RS) characteristics and mechanisms of RF-sputtered SrZrO3 (SZO)-based thin films are investigated in this paper. The physical and electrical properties of SZO-based thin films are modulated by vanadium doping due to the Zr4+ ion replaced by V5+, further affecting the RS parameters of SZO-based thin films. The conduction mechanisms of SZO-based thin

Meng-Han Lin; Ming-Chi Wu; Chen-Hsi Lin; Tseung-Yuen Tseng

2010-01-01

232

Resistive humidity sensor based on vanadium complex films  

NASA Astrophysics Data System (ADS)

A resistive-type relative humidity (RH) sensor based on vanadium complex (VO2(3-fl)) film is reported in this study. Gold electrodes were deposited on the glass substrates in a co-planar structure. A thin film of vanadium complex was coated as a humidity-sensing material on the top of the pre-patterned electrodes. The humidity-sensing principle of the sensor was based on the conductivity change of coated sensing element upon adsorption/desorption of water vapor. The resistance of the humidity sensor measured at 1 kHz decreased linearly with increasing the humidity in the range of 35%–70% RH. The overall resistance of the sensor decreases 11 times. An equivalent circuit for the VO2(3-fl) based resistive-type humidity sensor was developed. The properties of the sensor studied in this work make it beneficial for use in the instruments for environmental monitoring of humidity.

Karimov, Kh. S.; Saleem, M.; Mahroof-Tahir, M.; Akram, R.; Saeed Chanee, M. T.; Niaz, A. K.

2014-09-01

233

Advances in aluminum casting technology  

SciTech Connect

This symposium focuses on the improvements of aluminum casting quality and reliability through a better understanding of processes and process variables, and explores the latest innovations in casting-process design that allow increasing use of the castings to replace complex assemblies and heavy steel and cast-iron components in aerospace and automotive applications. Presented are 35 papers by international experts in the various aspects of the subject. The contents include: Semisolid casting; Computer-aided designing of molds and castings; Casting-process modeling; Aluminum-matrix composite castings; HIPing of castings; Progress in the US car project; Die casting and die design; and Solidification and properties.

Tiryakioglu, M.; Campbell, J. (eds.)

1998-01-01

234

Graphite Nodule and Eutectic Cell Count in Cast Iron: Theoretical Model Based on Weibull Statistics and Experimental Verification  

NASA Astrophysics Data System (ADS)

In this work, a model is proposed for heterogeneous nucleation on substrates whose size distribution can be described by the Weibull statistics. It is found that the nuclei density, N nuc can be given in terms of the maximum undercooling, ?T m , by N nuc = N s exp ( b/?T m ), where N s is the density of nucleation sites in the melt and b is the nucleation coefficient (b > 0). When nucleation occurs on all possible substrates, the graphite nodule density, N V,n , or eutectic cell density, N V , after solidification equals N s . In this work, measurements of N V,n and N V values were carried out on experimental nodular and flake graphite iron castings processed under various inoculation conditions. The volumetric nodule N V,n or graphite eutectic cell N V count was estimated from the area nodule count, N A,n , or eutectic cell count, N A , on polished cast iron surface sections by stereological means. In addition, maximum undercoolings, ?T m , were measured using thermal analysis. The experimental outcome indicates that the N V,n or N V count can be properly described by the proposed expression N V,n = N V = N s exp ( b/?T m ). Moreover, the N s and b values were experimentally determined. In particular, the proposed model suggests that the size distribution of nucleation sites is exponential in nature.

Fra?, E.; Wiencek, K.; Górny, M.; López, H. F.

2007-02-01

235

Beam casting implicit surfaces on the GPU with interval arithmetic  

E-print Network

Beam casting implicit surfaces on the GPU with interval arithmetic Francisco Ganacim, Luiz Henrique, Brazil Abstract--We present a GPU-based beam-casting method for rendering implicit surfaces in real time. INTRODUCTION Rendering surfaces with ray casting is perhaps the clearest example of a potentially

236

All-optical logic gates based on photoinduced anisotropy of bacteriorhodopsin film  

Microsoft Academic Search

All-optical logic gates based on photoinduced anisotropy of bacteriorhodopsin (BR) film are proposed. The photoinduced anisotropy in BR film, which arises from the selective absorption of BR molecules to polarized light, can be controlled by changing the amplitudes and polarizations of exiting beams. As a consequence, the polarization of the probe light passing through the BR film can be controlled

Junhe Han; Baoli Yao; Peng Gao; Liju Chen; Mingju Huang

2012-01-01

237

Sensors and Actuators B 49 (1998) 258267 Pd/PVDF thin film hydrogen sensor based on  

E-print Network

Sensors and Actuators B 49 (1998) 258­267 Pd/PVDF thin film hydrogen sensor based on laser thin film coated on a polymeric membrane, optical reflectance and transmittance signals are generated polyvinilydene fluoride (PVDF) thin-film photopy- roelectric (PPE) sensors [1,2]. The PPE sensor exhibits

Mandelis, Andreas

238

Electrospun aggregation-induced emission active POSS-based porous copolymer films for detection of explosives.  

PubMed

Electrospun aggregation-induced emission (AIE)-active polyhedral oligomeric silsesquioxane (POSS)-based copolymer films exhibit an approximately 9-fold increase in response to explosive vapors compared to dense films although porous copolymer films have a thickness as high as 560 ± 60 nm. PMID:25252003

Zhou, Hui; Ye, Qun; Neo, Wei Teng; Song, Jing; Yan, Hong; Zong, Yun; Tang, Ben Zhong; Hor, T S Andy; Xu, Jianwei

2014-10-14

239

Effect of Pressure Difference on the Quality of Titanium Casting  

Microsoft Academic Search

In casting titanium using a two-compartment casting machine, Herø et al. (1993) reported that the pressure difference between the melting chamber and the mold chamber affected the soundness of the castings. This study tested the hypothesis that differences in pressure produce castings with various amounts of porosity and different mechanical properties values. Plastic dumbbell-shaped patterns were invested with an alumina-based,

I. Watanabe; J. H. Watkins; H. Nakajima; M. Atsuta; T. Okabe

1997-01-01

240

Thin film transistors gas sensors based on reduced graphene oxide poly(3-hexylthiophene) bilayer film for nitrogen dioxide detection  

NASA Astrophysics Data System (ADS)

Reduced graphene oxide (RGO)/poly(3-hexylthiophene) (P3HT) bilayer films were firstly utilized as active layers in OTFT gas sensors for nitrogen dioxide (NO2) detection. The OTFT with RGO/P3HT bilayer film exhibited the typical transistor characteristics and better gas sensing properties at room temperature. The electrical parameters of OTFTs based on pure P3HT film and RGO/P3HT bilayer film were calculated. The threshold voltage of OTFT was positively shifted due to the high concentration carriers in RGO. The sensing properties of the sensor with RGO/P3HT bilayer film were also investigated. Moreover, the sensing mechanism was analyzed as well.

Xie, Tao; Xie, Guangzhong; Zhou, Yong; Huang, Junlong; Wu, Mei; Jiang, Yadong; Tai, Huiling

2014-10-01

241

Growth of hierarchical based ZnO micro\\/nanostructured films and their tunable wettability behavior  

Microsoft Academic Search

Hierarchical zinc oxide (ZnO) micro\\/nanostructured thin films were grown onto as-prepared and different annealed ZnO seed layer films by a simple two step chemical process. A cost effective successive ionic layer adsorption and reaction (SILAR) method was employed to grow the seed layer films at optimal temperature (80°C) and secondly, different hierarchical based ZnO structured thin films were deposited over

P. Suresh Kumar; A. Dhayal Raj; D. Mangalaraj; D. Nataraj; N. Ponpandian; Lin Li; G. Chabrol

2011-01-01

242

Release behavior and stability of encapsulated D-limonene from emulsion-based edible films.  

PubMed

Edible films may act as carriers of active molecules, such as flavors. This possibility confers to them the status of active packaging. Two different film-forming biopolymers, gluten and ?-carrageenans, have been compared. D-Limonene was added to the two film formulations, and its release kinetics from emulsion-based edible films was assessed with HS-SPME. Results obtained for edible films were compared with D-limonene released from the fatty matrix called Grindsted Barrier System 2000 (GBS). Comparing ?-carrageenans with gluten-emulsified film, the latter showed more interesting encapsulating properties: in fact, D-limonene was retained by gluten film during the process needed for film preparation, and it was released gradually during analysis time. D-Limonene did not show great affinity to ?-carrageenans film, maybe due to high aroma compound hydrophobicity. Carvone release from the three different matrices was also measured to verify the effect of oxygen barrier performances of edible films to prevent D-limonene oxidation. Further investigations were carried out by FT-IR and liquid permeability measurements. Gluten film seemed to better protect D-limonene from oxidation. Gluten-based edible films represent an interesting opportunity as active packaging: they could retain and release aroma compounds gradually, showing different mechanical and nutritional properties from those of lipid-based ingredients. PMID:23163743

Marcuzzo, Eva; Debeaufort, Frédéric; Sensidoni, Alessandro; Tat, Lara; Beney, Laurent; Hambleton, Alicia; Peressini, Donatella; Voilley, Andrée

2012-12-12

243

Process Modeling of Low-Pressure Die Casting of Aluminum Alloy Automotive Wheels  

NASA Astrophysics Data System (ADS)

Although on initial inspection, the aluminum alloy automotive wheel seems to be a relatively simple component to cast based on its shape, further insight reveals that this is not the case. Automotive wheels are in a select group of cast components that have strict specifications for both mechanical and aesthetic characteristics due to their important structural requirements and their visibility on a vehicle. The modern aluminum alloy automotive wheel continues to experience tightened tolerances relating to defects to improve mechanical performance and/or the physical appearance. Automotive aluminum alloy wheels are assessed against three main criteria: wheel cosmetics, mechanical performance, and air tightness. Failure to achieve the required standards in any one of these categories will lead to the wheel either requiring costly repair or being rejected and remelted. Manufacturers are becoming more reliant on computational process modeling as a design tool for the wheel casting process. This article discusses and details examples of the use of computational process modeling as a predictive tool to optimize the casting process from the standpoint of defect minimization with the emphasis on those defects that lead to failure of aluminum automotive wheels, namely, macroporosity, microporosity, and oxide films. The current state of applied computational process modeling and its limitations with regard to wheel casting are discussed.

Reilly, C.; Duan, J.; Yao, L.; Maijer, D. M.; Cockcroft, S. L.

2013-09-01

244

PVDF-PZT nanocomposite film based self-charging power cell.  

PubMed

A novel PVDF-PZT nanocomposite film has been proposed and used as a piezoseparator in self-charging power cells (SCPCs). The structure, composed of poly(vinylidene fluoride) (PVDF) and lead zirconate titanate (PZT), provides a high piezoelectric output, because PZT in this nanocomposite film can improve the piezopotential compared to the pure PVDF film. The SCPC based on this nanocomposite film can be efficiently charged up by the mechanical deformation in the absence of an external power source. The charge capacity of the PVDF-PZT nanocomposite film based SCPC in 240 s is ?0.010 ?A h, higher than that of a pure PVDF film based SCPC (?0.004 ?A h). This is the first demonstration of using PVDF-PZT nanocomposite film as a piezoseparator for SCPC, and is an important step for the practical applications of SCPC for harvesting and storing mechanical energy. PMID:24531887

Zhang, Yan; Zhang, Yujing; Xue, Xinyu; Cui, Chunxiao; He, Bin; Nie, Yuxin; Deng, Ping; Lin Wang, Zhong

2014-03-14

245

Thin-film filament-based solar cells and modules  

NASA Astrophysics Data System (ADS)

This concept paper describes a patented, novel photovoltaic (PV) technology that is capable of achieving near-term commercialization and profitability based upon design features that maximize product performance while minimizing initial and future manufacturing costs. DayStar Technologies plans to exploit these features and introduce a product to the market based upon these differential positions. The technology combines the demonstrated performance and reliability of existing thin-film PV product with a cell and module geometry that cuts material usage by a factor of 5, and enhances performance and manufacturability relative to standard flat-plate designs. The target product introduction price is 1.50/Watt-peak (Wp). This is approximately one-half the cost of the presently available PV product. Additional features include: increased efficiency through low-level concentration, no scribe or grid loss, simple series interconnect, high voltage, light weight, high-throughput manufacturing, large area immediate demonstration, flexibility, modularity.

Tuttle, J. R.; Cole, E. D.; Berens, T. A.; Alleman, J.; Keane, J.

1997-04-01

246

Direct milling and casting of polymer-based optical waveguides for improved transparency in the visible range  

NASA Astrophysics Data System (ADS)

Polymer waveguides fabricated from photoresist have an inherent high propagation loss in the short visible wavelength range caused by absorption due to the added photosensitizers. We have addressed this problem by development of two novel methods for the fabrication of microfluidic systems with integrated optical waveguides. Polymethylmethacrylate (PMMA) is dissolved in anisole and 'doped' with styrene-arcylonitrile copolymer to vary the refractive index. The doped PMMA with a higher refractive index is then spin coated onto a PMMA substrate with a lower refractive index to provide waveguide properties. Direct micromilling enabled us to fabricate 100 µm wide optical waveguides. Propagation losses of less than 1 dB cm-1 could be achieved throughout the entire visual range down to a wavelength of 400 nm. A casting process amenable to high number production of such devices was furthermore developed.

Snakenborg, D.; Perozziello, G.; Klank, H.; Geschke, O.; Kutter, J. P.

2006-02-01

247

Dimensional variability of production steel castings  

SciTech Connect

Work is ongoing to characterize the dimensional variability of steel casting features. Data are being collected from castings produced at representative Steel Founders` Society of America foundries. Initial results based on more than 12,500 production casting feature measurements are presented for carbon and low alloy steel castings produced in green sand, no-bake, and shell molds. A comprehensive database of casting, pattern, and feature variables has been developed so that the influence of the variables on dimensional variability can be determined. Measurement system analysis is conducted to insure that large measurement error is not reported as dimensional variability. Results indicate that the dimensional variability of production casting features is less than indicated in current US (SFSA) and international (ISO) standards. Feature length, casting weight, parting line and molding process all strongly influence dimensional variability. Corresponding pattern measurements indicate that the actual shrinkage amount for casting features varies considerably. This variation in shrinkage will strongly influence the ability of the foundry to satisfy customer dimensional requirements.

Peters, F.E.; Risteu, J.W.; Vaupel, W.G.; DeMeter, E.C.; Voigt, R.C.

1994-12-31

248

Improving Metal Casting Process  

NASA Technical Reports Server (NTRS)

Don Sirois, an Auburn University research associate, and Bruce Strom, a mechanical engineering Co-Op Student, are evaluating the dimensional characteristics of an aluminum automobile engine casting. More accurate metal casting processes may reduce the weight of some cast metal products used in automobiles, such as engines. Research in low gravity has taken an important first step toward making metal products used in homes, automobiles, and aircraft less expensive, safer, and more durable. Auburn University and industry are partnering with NASA to develop one of the first accurate computer model predictions of molten metals and molding materials used in a manufacturing process called casting. Ford Motor Company's casting plant in Cleveland, Ohio is using NASA-sponsored computer modeling information to improve the casting process of automobile and light-truck engine blocks.

1998-01-01

249

Tunable thin film filters based on thermo-optic semiconductor films  

NASA Astrophysics Data System (ADS)

Thermo-optic layers of thin film semiconductors are deposited by PEVCD to create thermally tunable bandpass filters for WDM optical networks. Amorphous semiconductor films, adapted from the solar cell and display industries, are the primary ingredient. Single-cavity tunable filters with FWHM=0.085 nm, >40 nm tuning range, and insertion losses 0.2-4 dB are demonstrated. Key enablers for this new family of index-tunable thin film devices are PECVD deposition, large internal temperature changes >400C, high conductivity polysilicon heater films, and extremely robust film adhesion. Possible applications include optical monitoring, add/drop multiplexing, dynamic gain equalization, and dispersion compensation.

Domash, Lawrence H.; Ma, Eugene Y.; Nemchuk, Nikolay; Payne, Adam; Wu, Ming

2003-02-01

250

Ion permeability of polydopamine films revealed using a prussian blue-based electrochemical method.  

PubMed

Polydopamine (PDA) is fast becoming a popular surface modification technique. Detailed understanding of the ion permeability properties of PDA films will improve their applications. Herein, we report for the first time the thickness-independent ion permeability of PDA films using a Prussian blue (PB)-based electrochemical method. In this method, PDA films are deposited via ammonium persulfate-induced dopamine polymerization onto a PB electrode. The ion permeability of the PDA films can thus be detected by observing the changes in electrochemical behaviors of the PB coated by PDA films. On the basis of this method, it was unexpectedly found that the PDA films with thickness greater than 45 nm (e.g., ?60 and ?113 nm) can exhibit pH-switchable but thickness-insensitive permeability to monovalent cations such as potassium and sodium ions. These observations clearly indicate the presence of a continuous network of interconnected intermolecular voids within PDA films, regardless of film thickness. PMID:25317484

Gao, Bowen; Su, Lei; Tong, Ying; Guan, Miao; Zhang, Xueji

2014-11-01

251

Crack width monitoring of concrete structures based on smart film  

NASA Astrophysics Data System (ADS)

Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge.

Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

2014-04-01

252

Effect of plasticizer (DMF) on electrical properties of PMMA based polymer electrolyte films  

NASA Astrophysics Data System (ADS)

Solid polymer electrolyte films of PMMA with NaClO4 and NaClO4+ plasticizer (dimethyl foramide) have been prepared by solution cast technique. DC conductivity of the films was measured in the temperature range 303-393 K. The variation of ionic conductivity as a function of temperature in polymer electrolyte was analyzed. In the temperature range studied, three regions with different activation energies were observed. Transference number data showed that the charge transport in this system is predominantly due to ions only. Electrochemical cells of configuration Na/(PMMA+NaClO4+DMF)/(I2+C+electrolyte) were fabricated and the discharge characteristics of these cells were studied under a constant load of 100K?. Several cell parameters associated with the cells were evaluated and compared with earlier reports.

Sekhar, P. Chandra; Kumar, P. Naveen; Sasikala, U.; Sharma, A. K.

2013-06-01

253

Design and evaluation of polysaccharide-based transdermal films for the controlled delivery of nifedipine.  

PubMed

It was aimed to develop the matrix type polysaccharide-based transdermal films of nifedipine (NFD) to provide its long term plasma concentration. The mechanical tests were carried out on gel formulations which were utilised in the fabrication of transdermal films to determine the type of polymer (pectin, sodium alginate) and plasticizer (propylene glycol, glycerine) as well as their concentrations. The mechanical strength, elasticity, bioadhesiveness and the drug release characteristics of optimised films containing NFD were evaluated. Permeation of NFD from the films with/without adding an enhancer (nerolidol) was followed through excised rat skin using Franz diffusion cells. Results showed that the gels composed of either pectin or sodium alginate were appropriate for the fabrication of transdermal films of NFD, and the addition of propylene glycol improved mechanical strength, flexibility, and bioadhesiveness of the films. Permeation data showed that nerolidol was an effective permeation enhancer for the polysaccharide-based transdermal films of NFD. PMID:24492584

Bekta?, Ay?egül; Cevher, Erdal; Güngör, Sevgi; Ozsoy, Y?ld?z

2014-01-01

254

National Metal Casting Research Institute final report. Volume 2, Die casting research  

SciTech Connect

Four subprojects were completed: development and evaluation of die coatings, accelerated die life characterization of die materials, evaluation of fluid flow and solidification modeling programs, selection and characterization of Al-based die casting alloys, and influence of die materials and coatings on die casting quality.

Jensen, D. [University of Northern Iowa, Cedar Falls, IA (United States). Dept. of Industrial Technology] [comp.

1994-06-01

255

Effect of Gamma Radiation on the Physico- and ThermoMechanical Properties of Gelatin-Based Films Using 2-Hydroxyethyl Methacrylate (HEMA)  

Microsoft Academic Search

Gelatin films were prepared from gelatin granules in aqueous medium by casting. Tensile strength, tensile modulus, elongation at break and the glass point of the gelatin films were found to be 27 MPa, 100 MPa, 4% and 51.7°C, respectively. After irradiated with gamma radiation tensile properties were increased due to denser network structure. Gelatin films were soaked in five different formulations containing

Sabrina Sultana; Ruhul A. Khan; Mubarak A. Khan; A. I. Mustafa; M. A. Gafur

2010-01-01

256

Optical corrosion sensor based on fiber Bragg grating electroplated with Fe-C film  

NASA Astrophysics Data System (ADS)

An optical fiber corrosion sensor (OFCS) based on iron-carbon (Fe-C) film was researched. OFCS was formed by electroplating a Fe-C film on fiber Bragg grating (FBG) metalized with silver film by magnetron sputtering. There was a more than 430-pm change of FBG wavelength when Fe-C film was seriously corroded. Compared to electrochemical method, the optical fiber sensor shows dominance in long-lasting monitoring of corrosion. The electric signal was broken off after the 20-h corrosion of Fe-C film, while the optical fiber sensor's monitoring lasted more than 40 days.

Zheng, Xing; Hu, Wenbin; Zhang, Ning; Gao, Min

2014-07-01

257

Hickey, W8206, all casts Hickey, W8206, all casts, page 1  

E-print Network

Hickey, W8206, all casts Hickey, W8206, all casts, page 1 #12;Hickey, W8206, all casts Hickey, W8206, all casts, page 2 #12;Hickey, W8206, all casts Hickey, W8206, all casts, page 3 #12;Hickey, W8206, all casts Hickey, W8206, all casts, page 4 #12;Hickey, W8206, all casts Hickey, W8206, all casts, page

Hickey, Barbara

258

Graphene-based supercapacitor with carbon nanotube film as highly efficient current collector.  

PubMed

Flexible graphene-based thin film supercapacitors were made using carbon nanotube (CNT) films as current collectors and graphene films as electrodes. The graphene sheets were produced by simple electrochemical exfoliation, while the graphene films with controlled thickness were prepared by vacuum filtration. The solid-state supercapacitor was made by using two graphene/CNT films on plastic substrates to sandwich a thin layer of gelled electrolyte. We found that the thin graphene film with thickness <1 ?m can greatly increase the capacitance. Using only CNT films as electrodes, the device exhibited a capacitance as low as ?0.4 mF cm(-2), whereas by adding a 360 nm thick graphene film to the CNT electrodes led to a ?4.3 mF cm(-2) capacitance. We experimentally demonstrated that the conductive CNT film is equivalent to gold as a current collector while it provides a stronger binding force to the graphene film. Combining the high capacitance of the thin graphene film and the high conductivity of the CNT film, our devices exhibited high energy density (8-14 Wh kg(-1)) and power density (250-450 kW kg(-1)). PMID:25301789

Notarianni, Marco; Liu, Jinzhang; Mirri, Francesca; Pasquali, Matteo; Motta, Nunzio

2014-10-31

259

Graphene-based supercapacitor with carbon nanotube film as highly efficient current collector  

NASA Astrophysics Data System (ADS)

Flexible graphene-based thin film supercapacitors were made using carbon nanotube (CNT) films as current collectors and graphene films as electrodes. The graphene sheets were produced by simple electrochemical exfoliation, while the graphene films with controlled thickness were prepared by vacuum filtration. The solid-state supercapacitor was made by using two graphene/CNT films on plastic substrates to sandwich a thin layer of gelled electrolyte. We found that the thin graphene film with thickness <1 ?m can greatly increase the capacitance. Using only CNT films as electrodes, the device exhibited a capacitance as low as ?0.4 mF cm?2, whereas by adding a 360 nm thick graphene film to the CNT electrodes led to a ?4.3 mF cm?2 capacitance. We experimentally demonstrated that the conductive CNT film is equivalent to gold as a current collector while it provides a stronger binding force to the graphene film. Combining the high capacitance of the thin graphene film and the high conductivity of the CNT film, our devices exhibited high energy density (8–14 Wh kg?1) and power density (250–450 kW kg?1).

Notarianni, Marco; Liu, Jinzhang; Mirri, Francesca; Pasquali, Matteo; Motta, Nunzio

2014-10-01

260

Near real-time estimation of tropospheric water vapour content from ground based GNSS data and its potential contribution to weather now-casting in Austria  

NASA Astrophysics Data System (ADS)

The importance of high resolution meteorological analysis of the atmosphere increased over the past years. A detailed analysis of the humidity field is an important precondition for a better monitoring of local and regional extreme precipitation events and for forecasts with improved spatial resolution. For this reason, the Austrian Meteorological Agency (ZAMG) is operating the spatial and temporal high resolution INCA system (Integrated Now-casting through Comprehensive Analysis) since begin of 2005. Errors in this analysis occur mainly in the areas of rapidly changing and hard to predict weather conditions or rugged topography with extreme differences in height such as the alpine area of Austria. The aim of this work is to provide GNSS based measurements of the tropospheric water vapour content with a temporal resolution of 1 h and a temporal delay of less than 1 h to assimilate these estimates into the INCA system. Additional requirement is an accuracy of better than 1 mm of the precipitable water (PW) estimates.

Karabati?, Ana; Weber, Robert; Haiden, Thomas

2011-05-01

261

The Effect of Casting Conditions on the High-Cycle Fatigue Properties of the Single-Crystal Nickel-Base Superalloy PWA 1483  

NASA Astrophysics Data System (ADS)

Different solidification conditions are employed to produce sets of single-crystal samples with different primary dendrite arm spacings, i.e., 600 ?m, 400 ?m, and 250 ?m. The material with the smaller dendrite arm spacing is shown to possess considerably increased high-cycle fatigue life. Fatigue cracks are found to originate from shrinkage porosity rather than from carbides, in which the size of the largest pores in the samples scales with the primary dendrite arm spacing. Fatigue life can be rationalized using a fracture mechanics approach based on a Kitagawa Takahashi plot. The impact of the results with respect to the development of new commercial casting processes that produce higher temperature gradients and cooling rates will be discussed.

Lamm, M.; Singer, R. F.

2007-06-01

262

Erosive Wear Behavior of Nickel-Based High Alloy White Cast Iron Under Mining Conditions Using Orthogonal Array  

NASA Astrophysics Data System (ADS)

Nihard Grade-4, a nickel-bearing cast iron widely used in slurry pumps and hydrodynamic components, is evaluated for its erosive wear response under mining conditions using a statistical approach. Experiments were conducted by varying the factors namely velocity, slurry concentration, angle of impingement, and pH in three levels, using L9 orthogonal array. Analysis of variance was used to rank the factors influencing erosive wear. The results indicate that velocity is the most influencing factor followed by the angle of impingement, slurry concentration, and pH. Interaction effects of velocity, slurry concentration, angle of impingement, and pH on erosion rate have been discussed. Wear morphology was also studied using SEM characterization technique. At lower angle (30°) of impingement, the erosion of material is by micro fracture and shallow ploughing with the plastic deformation of the ductile austenitic matrix. At the normal angle (90°) of impingement, the material loss from the surface is found because of deep indentation, forming protruded lips which are removed by means of repeated impact of the erodent.

Yoganandh, J.; Natarajan, S.; Babu, S. P. Kumaresh

2013-09-01

263

Carbon-based films coated 316L stainless steel as bipolar plate for proton exchange membrane fuel cells  

Microsoft Academic Search

Carbon-based films on 316L stainless steel were prepared as bipolar plates for proton exchange membrane fuel cells (PEMFCs) by pulsed bias arc ion plating. Three kinds of films were formed including the pure C film, the C–Cr composite film and the C–Cr–N composite film. Interfacial conductivity of the bipolar plate with C–Cr film was the highest, which showed great potential

Yu Fu; Guoqiang Lin; Ming Hou; Bo Wu; Zhigang Shao; Baolian Yi

2009-01-01

264

Amorphous Silicon(aSi:H) Thin Film Based Omnidirectional Control Solar Powered Vehicle  

Microsoft Academic Search

Through the paper, our goal is to drive a car with the help of thin film based solar cell. Mechanical and Electrical parts are assembled thereby. The main objective of this project is to collect maximum solar energy from the solar spectrum and use that solar energy to drive the car. Amorphous silicon based thin film solar panel has been

Abdullah Moinuddin; Jony C. Sarker; Akhter Zia

2012-01-01

265

Graded-reflectivity mirror based on a volume phase hologram in a photopolymer film  

E-print Network

Graded-reflectivity mirror based on a volume phase hologram in a photopolymer film Tian-Jie Chen phase holo- grams recorded in photopolymer films. A method for producing such holograms for the 1064-nm that calculated based on coupled-mode theory. The mirror can withstand a peak power density greater than 108 W cm2

266

Optical Sensors Based on Single Arm Thin Film Waveguide Interferometer  

NASA Technical Reports Server (NTRS)

Single-arm double-mode double-order optical waveguide interferometer utilizes interference between two propagating modes of different orders. Sensing effect results from the change in propagation conditions of the modes caused by the environment. The waveguide is made as an open asymmetric slab structure containing a dye-doped polymer film onto a fused quartz substrate. It is more sensitive to the change of environment than its conventional polarimetric analog using orthogonal modes (TE and TM) of the same order. The sensor still preserves the option of operating in polarimetric regime using a variety of mode combinations such as TE(sub 0)/TM(sub 0) (conventional), TE(sub 0)/TM(sub 1), TE(sub 1)/TM(sub 0), or TE(sub 1)/TM(sub 1) but can also work in nonpolarimetric regime using combinations TE(sub 0)/TM(sub 1) or TE(sub 0)/TM(sub 1). Utilization of different mode combinations simultaneously makes the device more versatile. Application of the sensor to gas sensing is based on doping polymer film with an organic indicator dye sensitive to a particular gas. Change of optical absorption spectrum of the dye caused by the gaseous pollutant results change of the reactive index of the dye-doped polymer film that can be detected by the sensor. As an indicator dyes, we utilize Bromocresol Purple doped into polymer poly(methyl) methacrylate, which shows a reversible growth of the absorption peak neat 600 nm after exposure to wet ammonia. We have built a breadboard prototype of the sensor with He-Ne laser as a light source and with a single mode fiber input and a multimode fiber output. The prototype showed sensitivity to temperature change of the order of 2 C per one full oscillation of the signal. The sensitivity of the sensor to the presence of wet ammonia is 200 ppm per one full oscillation of the signal. The further improvements include switching to a longer wavelength laser source (750-nm semiconductor laser), substitution of poly(methyl) methacrylate with hydrophilic high-temperature polyimide, and increase the doping rate of indicator dye. All these improvements are expected to bring sensitivity to 10 ppm of ammonia per one full oscillation of signal independent on the humidity of ambient air. The proposed sensor can be used as a robust and inexpensive stand-alone instrument for continuous environment pollution monitoring.

Sarkisov, S. S.; Diggs, D.; Curley, M.; Adamovsky, Grigory (Technical Monitor)

2001-01-01

267

Ultrasmooth and thermally stable silver-based thin films with subnanometer roughness by aluminum doping.  

PubMed

Rough surface and poor stability of ultrathin Ag films limit their applications in nanophotonic and optoelectronic devices. Here, we report an approach for fabricating ultrasmooth and thermally stable Ag-based thin films on SiO2/Si substrates by Al-doping. The effect of Al-doping on the surface morphology and stability of ultrathin Ag films at room temperature and elevated temperature was investigated. The 15 nm Al-doped Ag films with an Al atomic concentration of 4% have a root-mean-square roughness as low as 0.4 nm. The smooth surface morphology is maintained even after 300 °C annealing in N2. Al-doping enhances the nuclei density of films. Moreover, a capping layer spontaneously formed over the Al-doped Ag films restrains the surface diffusion and mass transportation of Ag atoms. Therefore, Al-doping induces ultrathin Ag films with highly stable and ultrasmooth surface morphology. PMID:25211394

Gu, Deen; Zhang, Cheng; Wu, Yi-Kuei; Guo, L Jay

2014-10-28

268

Air-Flow Navigated Crystal Growth for TIPS Pentacene-Based Organic Thin-Film Transistors  

SciTech Connect

6,13-bis(triisopropylsilylethynyl)pentacene (TIPS pentacene) is a promising active channel material of organic thin-film transistors (OTFTs) due to its solubility, stability, and high mobility. However, the growth of TIPS pentacene crystals is intrinsically anisotropic and thus leads to significant variation in the performance of OTFTs. In this paper, air flow is utilized to effectively reduce the TIPS pentacene crystal anisotropy and enhance performance consistency in OTFTs, and the resulted films are examined with optical microscopy, grazing-incidence X-ray diffraction, and thin-film transistor measurements. Under air-flow navigation (AFN), TIPS pentacene drop-cast from toluene solution has been observed to form thin films with improved crystal orientation and increased areal coverage on substrates, which subsequently lead to a four-fold increase of average hole mobility and one order of magnitude enhancement in performance consistency defined by the ratio of average mobility to the standard deviation of the field-effect mobilities.

He, Zhengran [ORNL] [ORNL; Chen, Jihua [ORNL] [ORNL; Sun, Zhenzhong [ORNL] [ORNL; Szulczewski, Greg [University of Alabama, Tuscaloosa] [University of Alabama, Tuscaloosa; Li, Dawen [ORNL] [ORNL

2012-01-01

269

Ellipsometric measurements for thin-film-based sensor systems  

NASA Astrophysics Data System (ADS)

The application of a highly birefringent fiber polarization modulation technique for ellipsometric measurements on sol-gel thin films is described. The ability of the system to determine the ellipsometric parameters of thin films is demonstrated. The system is then used to monitor the ellipsometric parameters of thin films on exposure to a perturbing environment of humidity and pressure. The potential of the system for application in chemical sensor systems is indicated and discussed.

Chitaree, Ratchapak; Murphy, V.; Weir, K.; Palmer, Andrew W.; Grattan, Kenneth T. V.; MacCraith, Brian D.

1995-09-01

270

Polyester-based thin films with high photosensitivity  

SciTech Connect

A great deal of research has been done to understand the photosensitive optical response of inorganic glasses, which exhibit a permanent, photo-induced refractive index change due to the presence of optically active point defects in the glass structure. In the present work, the authors have performed a preliminary study of the intrinsic photosensitivity of a polyester containing a cinnamylindene malonate group (CPE, a photo- and thermal-crosslinkable group) for use in photonic waveguide devices. Thin films of CPE (approximately 0.5 microns thick) were spun onto fused silica substrates. Optical absorption in the thin films was evaluated both before and after exposure to UV radiation sources. It was found that the polyester exhibits two dominant UV absorption bands centered about 240 nm and 330 nm. Under exposure to 337 nm radiation (nitrogen laser) a marked bleaching of the 330 nm band was observed. This band bleaching is a direct result of the photo-induced crosslinking in the cinnamylindene malonate group. Exposure to 248 nm radiation (excimer laser), conversely, resulted in similar bleaching of the 330 nm band but was accompanied by nearly complete bleaching of the higher energy 240 nm band. Based on a Kramers-Kronig analysis of the absorption changes, refractive index changes on the order of {minus}10{sup {minus}2} are estimated. Confirmation of this calculation has been provided via ellipsometry which estimates a refractive index change at 632 nm of {minus}0.061 {+-} 0.002. Thus, the results of this investigation confirm the photosensitive potential of this type of material.

POTTER,KELLY SIMMONS; POTTER JR.,BARRETT G.; WHEELER,DAVID R.; JAMISON,GREGORY M.

2000-02-29

271

Tethered Lubricant Films Based On Cross-linked Polydimethylsiloxane  

NASA Astrophysics Data System (ADS)

We report on the interfacial friction and wear properties of surface-tethered cross-linked polymer thin films. We show that thin, two-tiered films produced by covalently tethering polydimethylsiloxane (PDMS) networks to self-assembled monolayers manifest the lowest friction coefficient (mu = 0.0039) recorded for a dry lubricant film. Using a combination of lateral force microscopy, equilibrium swelling, and adhesion measurements we determine the physical processes responsible for these low friction coefficients. We also investigate the effect of free (unattached) and pendent polymer chains dispersed in thin PDMS network films on transient mechanical properties, interfacial friction, and wear characteristics.

Landherr, Lucas; Cohen, Claude; Archer, Lynden

2009-03-01

272

Sensitive films based on porous sol-gel silica  

NASA Astrophysics Data System (ADS)

The paper is devoted to the sensitive films for application in chemical sensors. These films, made of the sol-gel derived porous silica, were fabricated via a sol-gel dip-coating method. We have obtained silica layers of the minimum refractive index of ~ 1.22 and porosity ~47%. These layers were sensitized with a pH indocator - bromocresole purple. The indicator was introduced into porous silica layers by means of impregnation. Methods and results of characterization of porous silica films, before and after sensitization are presented in this paper. It was shown that films are very sensitive toward ammonia.

Karasi?ski, P.; Tyszkiewicz, C.; Szponik, M.; Rogozi?ski, R.

2014-05-01

273

Films  

NASA Astrophysics Data System (ADS)

In this paper, we investigated the microstructure and electrical properties of Bi2SiO5 (BSO) doped SrBi2Ta2O9 (SBT) films deposited by chemical solution deposition. X-ray diffraction observation indicated that the crystalline structures of all the BSO-doped SBT films are nearly the same as those of a pure SBT film. Through BSO doping, the 2Pr and 2Ec values of SBT films were changed from 15.3 ?C/cm2 and 138 kV/cm of pure SBT to 1.45 ?C/cm2 and 74 kV/cm of 10 wt.% BSO-doped SBT. The dielectric constant at 1 MHz for SBT varied from 199 of pure SBT to 96 of 10 wt.% BSO-doped SBT. The doped SBT films exhibited higher leakage current than that of non-doped SBT films. Nevertheless, all the doped SBT films still had small dielectric loss and low leakage current. Our present work will provide useful insights into the BSO doping effects to the SBT films, and it will be helpful for the material design in the future nonvolatile ferroelectric memories.

Li, Ming; Zhang, Yang; Shao, Yayun; Zeng, Min; Zhang, Zhang; Gao, Xingsen; Lu, Xubing; Liu, J.-M.; Ishiwara, Hiroshi

2014-09-01

274

High Efficiency Thin Film CdTe and a-Si Based Solar Cells Annual Technical Report for the Period  

E-print Network

High Efficiency Thin Film CdTe and a-Si Based Solar Cells Annual Technical Report for the Period This report covers the second year of this subcontract for research on high efficiency CdTe-based thin-film solar cells and on high efficiency a-Si-based thin-film solar cells. The effort on CdTe- based materials

Deng, Xunming

275

Characterization and performance of carbon films deposited by plasma and ion beam based techniques  

SciTech Connect

Plasma and ion beam based techniques have been used to deposit carbon-based films. The ion beam based method, a cathodic arc process, used a magnetically mass analyzed beam and is inherently a line-of-sight process. Two hydrocarbon plasma-based, non-line-of-sight techniques were also used and have the advantage of being capable of coating complicated geometries. The self-bias technique can produce hard carbon films, but is dependent on rf power and the surface area of the target. The pulsed-bias technique can also produce hard carbon films but has the additional advantage of being independent of rf power and target surface area. Tribological results indicated the coefficient of friction is nearly the same for carbon films from each deposition process, but the wear rate of the cathodic arc film was five times less than for the self-bias or pulsed-bias films. Although the cathodic arc film was the hardest, contained the highest fraction of sp{sup 3} bonds and exhibited the lowest wear rate, the cathodic arc film also produced the highest wear on the 440C stainless steel counterface during tribological testing. Thus, for tribological applications requiring low wear rates for both counterfaces, coating one surface with a very hard, wear resistant film may detrimentally affect the tribological behavior of the counterface.

Walter, K.C.; Kung, H.; Levine, T. [and others

1994-12-31

276

Thin-film chemical sensors based on electron tunneling  

NASA Technical Reports Server (NTRS)

The physical mechanisms underlying a novel chemical sensor based on electron tunneling in metal-insulator-metal (MIM) tunnel junctions were studied. Chemical sensors based on electron tunneling were shown to be sensitive to a variety of substances that include iodine, mercury, bismuth, ethylenedibromide, and ethylenedichloride. A sensitivity of 13 parts per billion of iodine dissolved in hexane was demonstrated. The physical mechanisms involved in the chemical sensitivity of these devices were determined to be the chemical alteration of the surface electronic structure of the top metal electrode in the MIM structure. In addition, electroreflectance spectroscopy (ERS) was studied as a complementary surface-sensitive technique. ERS was shown to be sensitive to both iodine and mercury. Electrolyte electroreflectance and solid-state MIM electroreflectance revealed qualitatively the same chemical response. A modified thin-film structure was also studied in which a chemically active layer was introduced at the top Metal-Insulator interface of the MIM devices. Cobalt phthalocyanine was used for the chemically active layer in this study. Devices modified in this way were shown to be sensitive to iodine and nitrogen dioxide. The chemical sensitivity of the modified structure was due to conductance changes in the active layer.

Khanna, S. K.; Lambe, J.; Leduc, H. G.; Thakoor, A. P.

1985-01-01

277

Casting in Sport  

PubMed Central

Attempts by sports medicine professionals to return high school athletes with hand and wrist injuries to competition quickly and safely have been the source of confusion and debate on many playing fields around the country. In addition to the differing views regarding the appropriateness of playing cast usage in high school football, a debate exists among sports medicine professionals as to which material is best suited for playing cast construction. Materials used in playing cast construction should be hard enough to provide sufficient stabilization to the injured area and include adequate padding to absorb blunt impact forces. The purpose of the biomechanical portion of this investigation was to attempt to determine the most appropriate materials for use in constructing playing casts for the hand and wrist by assessing different materials for: 1) hardness using a Shore durometer, and 2) ability to absorb impact using a force platform. Results revealed that RTV11 and Scotchcast were the “least hard” of the underlying casting materials and that Temper Stick foam greatly increased the ability of RTV11 to absorb impact. Assessment of the mechanical properties of playing cast materials and review of current developments in high school football rules are used to aid practitioners in choosing the most appropriate materials for playing cast construction. ImagesFig 1.Fig 2.Fig 3. PMID:16558257

DeCarlo, Mark; Malone, Kathy; Darmelio, John; Rettig, Arthur

1994-01-01

278

Silver nanowire-based transparent, flexible, and conductive thin film  

Microsoft Academic Search

The fabrication of transparent, conductive, and uniform silver nanowire films using the scalable rod-coating technique is described in this study. Properties of the transparent conductive thin films are investigated, as well as the approaches to improve the performance of transparent silver nanowire electrodes. It is found that silver nanowires are oxidized during the coating process. Incubation in hydrogen chloride (HCl)

Cai-Hong Liu; Xun Yu

2011-01-01

279

Planar plasmonic terahertz waveguides based on periodically corrugated metal films  

Microsoft Academic Search

We demonstrate that a one-dimensional periodically corrugated metal film can be used to create planar terahertz (THz) waveguides. The periodic corrugation is in the form of rectangular blind holes (i.e. holes that do not completely perforate the metal film) that are fabricated using a multilayer construction. The approach allows for the creation of structures in which the hole depth can

Gagan Kumar; Shashank Pandey; Albert Cui; Ajay Nahata

2011-01-01

280

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

Microsoft Academic Search

A dielectric structure pyrotechnic initiator was proposed and the initiator samples were designed and realized by integrating Ti\\/CuO-based reactive multilayer films on ceramic substrate. The dielectric structure consists of essentially two titanium films separated by a copper oxide (CuO) film, which is just like as a capacitor guaranteeing the initiator will not be discharged until the external voltage has exceeded

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

2011-01-01

281

Nanomechanical and nanotribological properties of carbon-based thin films: A review  

Microsoft Academic Search

Carbon-based thin films possess unique and adjustable combination of properties such as high hardness and wear resistance, chemical resistance and good tribological performances. Among critical variables to tailor a-C film’s properties for specific application is the distribution of the carbon hybridization states (sp1, sp2 and sp3 bonds), the atomic H content, the content in dopants such as Si, F, N,

C. A. Charitidis

2010-01-01

282

Wear and corrosion resistance of FeN based micrograin soft magnetic thin films  

Microsoft Academic Search

Wear resistance of Fe-N based micrograin and other soft magnetic thin films was measured using commercial 8 mm VCR and tapes. Fe-Ta-N and Fe-Al-N films which contain ceramics phase such as Ta-N show a high Vickers hardness, but their wear resistance was not the highest one. Fe-Ru-Ga-Si and Fe-Al-V-Nb-O-N films showed low wear loss when they were rubbed by ME

Kenji Katori; Hiroyuki Ohmori; Mitsuharu Shoji; Kazuhiko Hayashi

1994-01-01

283

Mechanisms of stabilization of earthworm casts and artificial casts  

Microsoft Academic Search

Fresh casts were collected from the earthworm species Aporrectodea caliginosa, and artificial casts were also made. The casts were subjected to ageing, drying-rewetting, and sterilization by hexanol vapour. Clay dispersion was determined, as a measure of the lack of stability of the casts. Two soils were used, the topsoil of a recently reclaimed polder soil in the Netherlands and the

J. C. Y. Marinissen; A. R. Dexter

1990-01-01

284

Silver nanowire-based transparent, flexible, and conductive thin film  

PubMed Central

The fabrication of transparent, conductive, and uniform silver nanowire films using the scalable rod-coating technique is described in this study. Properties of the transparent conductive thin films are investigated, as well as the approaches to improve the performance of transparent silver nanowire electrodes. It is found that silver nanowires are oxidized during the coating process. Incubation in hydrogen chloride (HCl) vapor can eliminate oxidized surface, and consequently, reduce largely the resistivity of silver nanowire thin films. After HCl treatment, 175 ?/sq and approximately 75% transmittance are achieved. The sheet resistivity drops remarkably with the rise of the film thickness or with the decrease of transparency. The thin film electrodes also demonstrated excellent flexible stability, showing < 2% resistance change after over 100 bending cycles. PMID:21711602

2011-01-01

285

Cellulose triacetate, thin film dielectric capacitor  

NASA Technical Reports Server (NTRS)

Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

Yen, Shiao-Ping S. (inventor); Jow, T. Richard (inventor)

1995-01-01

286

Cellulose triacetate, thin film dielectric capacitor  

NASA Technical Reports Server (NTRS)

Very thin films of cellulose triacetate are cast from a solution containing a small amount of high boiling temperature, non-solvent which evaporates last and lifts the film from the casting surface. Stretched, oriented, crystallized films have high electrical breakdown properties. Metallized films less than about 2 microns in thickness form self-healing electrodes for high energy density, pulsed power capacitors. Thicker films can be utilized as a dielectric for a capacitor.

Yen, Shiao-Ping S. (inventor); Jow, T. Richard (inventor)

1993-01-01

287

Corrosive wear of cast iron under reciprocating lubrication  

SciTech Connect

In order to study the wear of cylinder bore fundamentally, a reciprocating friction tester was produced and utilized. The friction between a cast iron and a piston-ring and the wear of the cast iron were examined under the corrosive oil with sulphuric acid. The findings indicate that the friction and wear around TDC and BDC was confirmed to be greater than between these reversal points and the friction and wear around the reversal points increased with the sulphuric acid which has caused the deficiency of oil film and the corrosion of the cast iron.

Yahagi, Y.; Nagasawa, Y.; Hotta, S.; Mizutani, Y.

1986-01-01

288

Versatile fluoride substrates for Fe-based superconducting thin films  

NASA Astrophysics Data System (ADS)

We demonstrate the growth of Co-doped BaFe2As2 (Ba-122) thin films on CaF2 (001), SrF2 (001), and BaF2 (001) single crystal substrates using pulsed laser deposition. All films are grown epitaxially despite of a large misfit of -10.6% for BaF2 substrate. For all films, a reaction layer is formed at the interface confirmed by X-ray diffraction and for the films grown on CaF2 and BaF2 additionally by transmission electron microscopy. The superconducting transition temperature of the film on CaF2 is around 27 K, whereas the corresponding values of the films on SrF2 and BaF2 are around 22 K and 21 K, respectively. The Ba-122 on CaF2 shows almost identical crystalline quality and superconducting properties as films on Fe-buffered MgO.

Kurth, F.; Reich, E.; Hänisch, J.; Ichinose, A.; Tsukada, I.; Hühne, R.; Trommler, S.; Engelmann, J.; Schultz, L.; Holzapfel, B.; Iida, K.

2013-04-01

289

Water vapor adsorption isotherms of agar-based nanocomposite films.  

PubMed

Adsorption isotherms of agar and agar/clay nanocomposite films prepared with different types of nanoclays, that is, a natural montmorillonite (Cloisite Na(+) ) and 2 organically modified montmorillonites (Cloisite 30B and Cloisite 20A), were determined at 3 different temperatures (10, 25, and 40 °C). The water vapor adsorption behavior of the nanocomposite films was found to be greatly influenced with the type of clay. The Guggenheim-Anderson-de Boer (GAB) isotherm model parameters were estimated by using both polynomial regression and nonlinear regression methods and it was found that the GAB model fitted adequately for describing experimental adsorption isotherm data for the film samples. The monolayer moisture content (m(o) ) of the film samples was also greatly affected by the type of nanoclay used, that is, m(o) of nanocomposite films was significantly lower than that of the neat agar film. Nanocomposite films prepared with hydrophobic nanoclays (Cloisite 30B and Cloisite 20A) exhibited lower m(o) values than those prepared with hydrophilic nanoclay (Cloisite Na(+) ). PMID:22417601

Rhim, Jong-Whan

2011-10-01

290

Electrophoretically deposited polyaniline nanotubes based film for cholesterol detection.  

PubMed

Polyaniline nanotube (PANI-NT) based films have been fabricated onto indium-tin-oxide (ITO) coated glass plates via electrophoretic technique. These PANI-NT/ITO electrodes have been utilized for covalent immobilization of cholesterol oxidase (ChOx) using glutaraldehyde (Glu) as cross-linker. Structural, morphological and electrochemical characterization of PANI-NT/ITO electrode and ChOx/Glu/PANI-NT/ITO bioelectrode have been done using FT-IR spectroscopy, SEM, electrochemical impedance spectroscopy and cyclic voltammetry techniques. Response studies of the ChOx/Glu/PANI-NT/ITO bioelectrode have been carried out using both linear sweep voltammetry and UV-Visible spectrophotometry. The results of the biosensing studies reveal that this bioelectrode can be used to detect cholesterol in wide detection range of 25-500 mg/dL with high sensitivity of 3.36 mA mg(-1) dL and fast response time of 30 s at pH 7.4. This bioelectrode exhibits very low value of Michaelis-Menten constant of 1.18 mM indicating enhanced interactions between cholesterol and ChOx immobilized onto this nanostructured PANI matrix. PMID:21077243

Dhand, Chetna; Solanki, Pratima R; Pandey, Manoj K; Datta, Monika; Malhotra, Bansi D

2010-11-01

291

Influence of film growth conditions on carrier mobility of hot wall epitaxially grown fullerene based transistors  

NASA Astrophysics Data System (ADS)

Hot wall epitaxially grown C 60 based organic field-effect transistors (OFETs) show relatively high electron mobilities of 0.4-1 cm 2/Vs. We report results of thin film grown with various growth conditions such as preheating and initial substrate temperatures resulting in strikingly different fullerene film nanomorphology. The mobility is enhanced up to 3 cm 2/Vs for films grown at a substrate temperatures of 130 °C. This improvement in the mobility is explained in terms of a transition from a disordered interface consisting of small-elongated grains to a well-ordered C 60 film with bigger and rounder grains.

Montaigne Ramil, A.; Singh, Th. B.; Haber, N. T.; Marjanovi?, N.; Günes, S.; Andreev, A.; Matt, G. J.; Resel, R.; Sitter, H.; Sariciftci, S.

2006-02-01

292

Characterization of antioxidant methylcellulose film incorporated with ?-tocopherol nanocapsules.  

PubMed

Biodegradable and antioxidant films based on methylcellulose (MC) and ?-tocopherol nanocapsule suspension (NCs) were developed. MC and NCs films were prepared by a casting method in three different proportions. The mechanical, wettability, colour, light transmission, antioxidant and release characteristics of the films were studied. The addition of NCs to MC films decreased the tensile strength (TS) and the elastic modulus (EM) (p<0.05) but increased the percentage elongation at break (%E) and thickness (p<0.05). NCs films showed a higher hydrophobicity when compared to that of film control. Lightness and yellowish color were intensified in the NCs films which, in their turn, demonstrated high antioxidant activity and excellent barrier properties against UV and visible light. A burst and prolonged release of ?-tocopherol to food simulant was also reported. PMID:24767092

Noronha, Carolina Montanheiro; de Carvalho, Sabrina Matos; Lino, Renata Calegari; Barreto, Pedro Luiz Manique

2014-09-15

293

Optical thin film synthesis program based on the use of Fourier transforms  

E-print Network

Optical thin film synthesis program based on the use of Fourier transforms J. A. Dobrowolski and D the essential equations necessaryfor the implementation of Sossi's formulation of the FT thin film synthesis There exist two basic approaches to the synthesis of optical multilayer systems with irregular spectral

Lowe, David

294

Subwavelength plasmonic waveguide structures based on slots in thin metal films  

E-print Network

Subwavelength plasmonic waveguide structures based on slots in thin metal films Georgios Veronis,2]. In particular, plasmonic waveguides have shown the potential to guide subwavelength optical modes. Several length. 2. Guided subwavelength plasmonic mode supported by a slot in a thin metal film We first

Veronis, Georgios

295

Characterisation of gelatin–fatty acid emulsion films based on blue shark ( Prionace glauca) skin gelatin  

Microsoft Academic Search

Incorporation of fatty acids (stearic and oleic) into edible films based on blue shark (Prionace glauca) skin gelatin was investigated to modify properties such as water vapour barrier and flexibility due to their hydrophobicity and plasticizing effect, respectively. Addition of stearic acid from 0% to 100% of protein concentration in the film-forming solution considerably decreased water vapour permeability of gelatin–fatty

Kanokrat Limpisophon; Munehiko Tanaka; Kazufumi Osako

2010-01-01

296

Surface plasmon resonance biochip based on ZnO thin film for nitric oxide sensing  

Microsoft Academic Search

In this study, the design of a novel optical sensor that comprises surface plasmon resonance sensing chip and zinc oxide nano-film was proposed for the detection of nitric oxide gas. The electrical and optical properties of zinc oxide film vary in the presence of nitric oxide. This effect was utilized to prepare biochemical sensors with transduction based on surface plasmon

Wei-Yi Fenga; Nan-Fu Chiub; Hui-Hsin Lub; Hsueh-Ching Shihc; Dongfang Yangd; Chii-Wann Lina

2008-01-01

297

A Multifunctional Tactile Sensor Based on PVDF Films for Identification of Materials  

Microsoft Academic Search

A new multifunctional tactile sensor based on polyvinylidene fluoride (PVDF) films has been developed for material identification. In the sensor, the voltages induced by the electrostatic and piezoelectric effects (contact voltages) at the contact between the sensor and a sample are measured by a PVDF film. The voltage induced by the electrostatic effect is measured by the front electrode of

Akira Kimoto; Naoki Sugitani; Shintarou Fujisaki

2010-01-01

298

Thin and Thick Films Materials Based Interconnection Technology for 500 C Operation.  

National Technical Information Service (NTIS)

Precious metal based thick-film material was used for printed wires, wire bond pads, test lead-attach, and conductive die-attach for high temperature (up to 500 C and beyond) chip level packaging. A SiC Shottky diode with a thin-film coated backside was a...

G. W. Hunter, L. Y. Chen, P. G. Neudeck

2000-01-01

299

Casting Characteristics of Aluminum Die Casting Alloys  

SciTech Connect

The research program investigates the casting characteristics of selected aluminum die casting alloys. Specifically, the alloys' tendencies towards die soldering and sludge formation, and the alloys' fluidity and machinability are evaluated. It was found that: When the Fe and Mn contents of the alloy are low; caution has to be taken against possible die soldering. When the alloy has a high sludge factor, particularly a high level of Fe, measures must be taken to prevent the formation of large hardspots. For this kind of alloy, the Fe content should be kept at its lowest allowable level and the Mn content should be at its highest possible level. If there are problems in die filling, measures other than changing the alloy chemistry need to be considered first. In terms of alloy chemistry, the elements that form high temperature compounds must be kept at their lowest allowable levels. The alloys should not have machining problems when appropriate machining techniques and machining parameters are used.

Makhlouf M. Makhlouf; Diran Apelian

2002-02-05

300

Optical characterization of TiAlON-based film used for solar energy  

NASA Astrophysics Data System (ADS)

Optical characterization of TiAlON film applied in solar energy is presented in this paper. TiAlON-based films with different thicknesses have been deposited by magnetron sputtering. The spectrophotometer and spectroscopic ellipsometry (GES5) have been used to study the samples. Surface morphology and component of the films were investigated using scanning electron microscope (SEM), X-ray diffraction (XRD), atomic force microscope (AFM) and X-ray photoelectron spectroscopy (XPS). The optical constants and film thicknesses of TiAlON films with different thicknesses have been obtained by theoretical modeling analysis fitting (Cauchy model) and point-to-point analysis fitting. Results show that the refraction coefficient and extinction coefficient change with the film thickness increased. Those optical properties are useful for selecting the layers with adequate optical constants and thickness to design a solar selective absorber.

Zhao, Minglin; Lian, Jie; Sun, Zhaozong; Wang, Xiao; Zhang, Wenfu; Hu, Juanjuan; Li, Mengmeng

2014-09-01

301

Electrodeposited Fe-Co films prepared from a citric-acid-based plating bath  

NASA Astrophysics Data System (ADS)

Electrodeposited Fe-Co films are commonly prepared in a boric-acid-based bath. In this research, we applied citric acid instead of boric acid for the plating of Fe-Co films because boron in the waste bath is restricted by environmental-protection regulations in Japan. We evaluated the effect of citric acid on the magnetic and structural properties of the films. The saturation magnetization of the Fe-Co films slightly increased while the Fe content in the Fe-Co films decreased with increasing citric acid concentration. The lowest coercivity value of 240 A/m was obtained at a citric acid concentration of 100 g/L. The plating bath with this citric acid concentration enabled us to obtain Fe-Co films with high saturation magnetizations and smooth surface morphologies.

Yanai, T.; Uto, H.; Shimokawa, T.; Nakano, M.; Fukunaga, H.; Suzuki, K.

2013-06-01

302

Thin film porous membranes based on sol-gel chemistry for catalytic sensors  

SciTech Connect

Nanoporous sol-gel based films are finding a wide variety of uses including gas separations and supports for heterogeneous catalysts. The films can be formed by spin or dip coating, followed by relatively low temperature annealing. The authors used several types of these films as coatings on the Pd alloy thin film sensors they had previously fabricated and studied. The sol-gel films have little effect on the sensing response to H{sub 2} alone. However, in the presence of other gases, the nanoporous film modifies the sensor behavior in several beneficial ways. (1) They have shown that the sol-gel coated sensors were only slightly poisoned by high concentrations of H{sub 2}S while uncoated sensors showed moderate to severe poisoning effects. (2) For a given partial pressure of H{sub 2}, the signal from the sensor is modified by the presence of O{sub 2} and other oxidizing gases.

Hughes, R.C.; Patel, S.V.; Jenkins, M.W.; Boyle, T.J.; Gardner, T.J.; Brinker, C.J.

1998-05-01

303

Physicochemical and antimicrobial properties of citral and quercetin incorporated kafirin-based bioactive films.  

PubMed

The aim of this study was to determine the physicochemical and antimicrobial properties of kafirin-based bioactive films incorporating the plant essential oil citral and the polyphenol quercetin. The addition of quercetin and citral both imparted a yellowish colour to the films. The tensile strength of films significantly decreased and elongation at break increased when citral was incorporated, whereas addition of quercetin did not alter these two film parameters. The rate of water vapour transmission of the films decreased with citral incorporation but the water vapour permeability was not affected by either citral or quercetin incorporation. Furthermore, incorporation of citral and quercetin significantly lowered the oxygen permeability of the films. Film made of kafirin alone had antimicrobial activity against Listeria monocytogenes, however, films incorporating citral exhibited the highest antimicrobial activity against Campylobacter jejuni, L. monocytogenes, and Pseudomonas fluorescens. These results suggest that kafirin-based films incorporating citral and quercetin have potential as bioactive packaging to improve food safety and quality. PMID:25172719

Giteru, Stephen Gitonga; Coorey, Ranil; Bertolatti, Dean; Watkin, Elizabeth; Johnson, Stuart; Fang, Zhongxiang

2015-02-01

304

TiNi-based thin films for MEMS applications  

E-print Network

In this paper, some critical issues and problems in the development of TiNi thin films were discussed, including preparation and characterization considerations, residual stress and adhesion, frequency improvement, fatigue ...

Fu, Yongqing

305

Chitosan based edible films and coatings: a review.  

PubMed

Chitosan is a biodegradable biocompatible polymer derived from natural renewable resources with numerous applications in various fields, and one of which is the area of edible films and coatings. Chitosan has antibacterial and antifungal properties which qualify it for food protection, however, its weak mechanical properties, gas and water vapor permeability limit its uses. This review discusses the application of chitosan and its blends with other natural polymers such as starch and other ingredients for example essential oils, and clay in the field of edible films for food protection. The mechanical behavior and the gas and water vapor permeability of the films are also discussed. References dealing with the antimicrobial behavior of these films and their impact on food protection are explored. PMID:23498203

Elsabee, Maher Z; Abdou, Entsar S

2013-05-01

306

Predicting Pattern Tooling and Casting Dimensions for Investment Casting - Phase II  

SciTech Connect

The investment casting process allows the production of complex-shape parts and close dimensional tolerances. One of the most important phases in the investment casting process is the design of the pattern die. Pattern dies are used to create wax patterns by injecting wax into dies. The wax patterns are used to create a ceramic shell by the application of a series of ceramic coatings, and the alloy is cast into the dewaxed shell mold (Fig. 1.1). However, the complexity of shape and the close dimensional tolerances required in the final casting make it difficult to determine tooling dimensions. The final linear dimension of the casting depends on the cumulative effects of the linear expansions or contractions in each step of the investment casting process (Fig. 1.2). In most cases, the mold geometry or cores restrict the shrinkage of the pattern or the cast part, and the final casting dimensions may be affected by time-dependent processes such as viscoelastic deformation of the wax, and viscoplastic creep and plastic deformations of the shell and alloy. The pattern die is often reworked several times to produce castings whose dimensions are within acceptable tolerances. To date, investment casting technology has been based on hands-on training and experience. Technical literature is limited to experimental, phenomenological studies aimed at obtaining empirical correlations for quick and easy application in industry. The goal of this project was to predict casting dimensions for investment castings in order to meet blueprint nominal during the first casting run. Several interactions have to be considered in a coupled manner to determine the shrinkage factors: these are the die-wax, wax-shell, and shell-alloy interactions (as illustrated in Fig. 1.3). In this work, the deformations of the die-wax and shell-alloy systems were considered in a coupled manner, while the coupled deformation of the wax-shell system was not considered. Future work is needed in order to deliver to industry a computer program in which all three systems are coupled for determining the dimensions of the wax pattern, the shell mold, and casting in a sequential but coupled manner.

Sabau, Adrian S [ORNL

2005-09-01

307

In situ X-ray diffraction based investigation of crystallization in solution deposited PZT thin films  

NASA Astrophysics Data System (ADS)

Solution deposited PZT based thin films have potential applications in embedded decoupling capacitors and pulse discharge capacitors. During solution deposition, precursor solution is deposited onto a substrate to obtain an amorphous film. The film is then crystallized by heating it at a high temperature (˜600 - 700°C). Conditions during the crystallization anneal such as precursor stoichiometry in solution, heating rate and adhesion layer in the substrate are known to influence phase and texture evolution in these films. However, a mechanistic understanding of the changes taking place in these thin films during crystallization is lacking. A better understanding of the crystallization processes in these thin films could enable tailoring the properties of thin films to suit specific applications. To explore the crystallization process in solution deposited PZT thin films, high temperature in situ laboratory and synchrotron X-ray diffraction based techniques were developed. Taking advantage of the high X-ray flux available at synchrotron facilities such as beamline 6-ID-B, Advanced Photon Source, Argonne National Laboratory, crystalline phases formed in the thin films during crystallization at the high heating rates (0.5 -- 60°C/s) typically used during film processing could be measured. Using a 2-D detector for these measurements allowed the simultaneous measurement of both phase and texture information during crystallization. Analytical treatment of the unconventional diffraction geometry used during the synchrotron based measurements was performed to develop methodologies for quantitative estimation of texture components. The nominal lead content in the starting solutions and the heating rate used during crystallization was observed to influence the sequence of phases formed during crystallization of the films. In films crystallized at fast heating rates, titanium segregation, probably due to diffusion of titanium from the adhesion layer, was observed. To further investigate the effect of adhesion layer on the crystallization behavior of these films, PZT films were solution deposited onto substrates with titanium (Ti), titanium oxide (TiO x) and zinc oxide (ZnO) adhesion layers. Phase evolution was observed to be unaffected by the adhesion layer. (111) oriented PZT films were obtained on all substrates and hence Ti diffusion from the adhesion layer appeared to have limited influence on texture control in these films. It is suggested that the (111) orientation of the perovskite phase is directly seeded by the Pt(111) texture.

Nittala, Krishna

308

An approach to conductometric immunosensor based on phthalocyanine thin film  

Microsoft Academic Search

A new approach to conductometric biosensors utilizing iodine-sensitive phthalocyanine thin films has been proposed. The excellent sensitivity of the tetra-tert-butyl copper phthalocyanine (ttb-CuPc) to free iodine was used for the first time to detect a peroxidase-initiated reaction in an aqueous medium. To minimize the interfering effect of aqueous electrolytes on the impedance responses of the ttb-CuPc film itself, Au\\/Cr interdigitated

T. A. Sergeyeva; N. V. Lavrik; A. E. Rachkov; Z. I. Kazantseva; A. V. El'skaya

1998-01-01

309

A tunable hybrid metamaterial absorber based on vanadium oxide films  

Microsoft Academic Search

A tunable hybrid metamaterial absorber (MA) in the microwave band was designed, fabricated and characterized. The hybrid MA was realized by incorporating a VO2 film into the conventional resonant MA. By thermally triggering the insulator–metal phase transition of the VO2 film, the impedance match condition was broken and a deep amplitude modulation of about 63.3% to the electromagnetic wave absorption

Qi-Ye Wen; Huai-Wu Zhang; Qing-Hui Yang; Zhi Chen; Yang Long; Yu-Lan Jing; Yuan Lin; Pei-Xin Zhang

2012-01-01

310

Evaluation and improvement in the accuracy of a charge-coupled-device-based pyrometer for temperature field measurements of continuous casting billets.  

PubMed

This paper presents a radiometric high-temperature field measurement model based on a charge-coupled-device (CCD). According to the model, an intelligent CCD pyrometer with a digital signal processor as the core is developed and its non-uniformity correction algorithm for reducing the differences in accuracy between individual pixel sensors is established. By means of self-adaptive adjustment for the light-integration time, the dynamic range of the CCD is extended and its accuracy in low-temperature range is improved. The non-uniformity correction algorithm effectively reduces the accuracy differences between different pixel sensors. The performance of the system is evaluated through a blackbody furnace and an integrating sphere, the results of which show that the dynamic range of 400 K is obtained and the accuracy in low temperature range is increased by 7 times compared with the traditional method based on the fixed light-integration time. In addition, the differences of accuracy between the on-axis pixel and the most peripheral pixels are decreased from 19.1 K to 2.8 K. Therefore, this CCD pyrometer ensures that the measuring results of all pixels tend to be equal-accuracy distribution across the entire measuring ranges. This pyrometric system has been successfully applied to the temperature field measurements in continuous casting billets. PMID:23822369

Bai, Haicheng; Xie, Zhi; Zhang, Yuzhong; Hu, Zhenwei

2013-06-01

311

Salvaged castings and methods of salvaging castings with defective cast cooling bumps  

DOEpatents

Castings for gas turbine parts exposed on one side to a high-temperature fluid medium have cast-in bumps on an opposite cooling surface side to enhance heat transfer. Areas on the cooling surface having defectively cast bumps, i.e., missing or partially formed bumps during casting, are coated with a braze alloy and cooling enhancement material to salvage the part.

Johnson, Robert Alan (Simpsonville, SC); Schaeffer, Jon Conrad (Greenville, SC); Lee, Ching-Pang (Cincinnati, OH); Abuaf, Nesim (Lincoln City, OR); Hasz, Wayne Charles (Pownal, VT)

2002-01-01

312

Controlling coverage of solution cast materials with unfavourable surface interactions  

NASA Astrophysics Data System (ADS)

Creating uniform coatings of a solution-cast material is of central importance to a broad range of applications. Here, a robust and generic theoretical framework for calculating surface coverage by a solid film of material de-wetting a substrate is presented. Using experimental data from semiconductor thin films as an example, we calculate surface coverage for a wide range of annealing temperatures and film thicknesses. The model generally predicts that for each value of the annealing temperature there is a range of film thicknesses leading to poor surface coverage. The model accurately reproduces solution-cast thin film coverage for organometal halide perovskites, key modern photovoltaic materials, and identifies processing windows for both high and low levels of surface coverage.

Burlakov, V. M.; Eperon, G. E.; Snaith, H. J.; Chapman, S. J.; Goriely, A.

2014-03-01

313

Round scad protein-based film: Storage stability and its effectiveness for shelf-life extension of dried fish powder  

Microsoft Academic Search

Storage stability of different round scad (Decapterus maruadsi) protein-based films including (1) control film without palm oil and chitosan, (2) film with 25% palm oil (glycerol substitution) and (3) film with 25% palm oil and 40% chitosan (protein substitution) was investigated. During storage (54% relative humidity, 28–30°C), tensile strength (TS) of the films without and with 25% palm oil or

Anuchit Artharn; Thummanoon Prodpran; Soottawat Benjakul

2009-01-01

314

Molecular and Culture-Based Analyses of Prokaryotic Communities from an Agricultural Soil and the Burrows and Casts of the Earthworm Lumbricus rubellus  

Microsoft Academic Search

The microbial populations in no-till agricultural soil and casts of the earthworm Lumbricus rubellus were examined by culturing and molecular methods. Clone libraries of the 16S rRNA genes were prepared from DNA isolated directly from the soil and earthworm casts. Although no single phylum dominated the soil library of 95 clones, the largest numbers of clones were from Acidobacteria (14%),

Michelle A. Furlong; David R. Singleton; David C. Coleman; William B. Whitman

2002-01-01

315

films  

NASA Astrophysics Data System (ADS)

With various pulse laser energy ( E pulse), La2/3Ca1/3MnO3:Ag x [La1- x Ca x MnO3 (LCMO):Ag x , x = 0.04, wt%] films were prepared on vicinal cut LaAlO3 substrates by the pulsed laser deposition technique. It is found that laser-induced voltage (LIV) of LCMO:Ag0.04 films was improved and enhanced by E pulse. With E pulse increasing, figure of merit ( F m) and anisotropic Seebeck coefficient (? S) of LCMO:Ag0.04 films reached the maximum value of 109.8 mV/ns and 0.29 ?V/K for E pulse = 300 mJ. The results suggested that the LIV enhancement of LCMO:Ag0.04 films was due to Seebeck tensor improvement, the high crystallization and oxygen balance in LCMO:Ag0.04 films.

Liu, Xiang; Guo, Zhi-ping; Chen, Qing-ming; Cao, Ming-gang; Duan, Yun-biao

2014-08-01

316

Nitrogen-doped iron-film-based laminated materials for thin-film recording heads  

NASA Astrophysics Data System (ADS)

We have systematically studied nitrogen-doped iron (FeN) multilayer films aiming to achieve very small coercivity and near-zero magnetostriction simultaneously by varying the multilayer structure and sputtering parameters used to deposit the FeN layers. Multilayers using SiO2, NiFe, and CoZrRe have been studied. Films with a saturation magnetization of above 20 kG, a coercivity of 0.4 Oe, a magnetostriction constant of less than 5 × 10-7, and a hard-axis dc permeability of 4000 have been obtained.

Wang, S.; Kryder, M. H.

1991-04-01

317

Slip casting of partially stabilized zirconia  

SciTech Connect

The toughness of partially-stabilized zirconia has been studied for some time. The tetragonal phase in partially stabilized ZrO2 transforms to the monoclinic phase under the influence of stress. Partially-stabilized ZrO2 has enhanced tensile strength, good wear resistance and low friction coefficient, and has found industrial applications. This article describes the use of partially-stabilized zirconia in slip casting. Lab techniques of slip casting have been reported for nonplastic materials such as Al2O3, CaF2, CaO-stabilized ZrO2 and MgO. The article discusses the variation of slip density and firing temperature and also reports the preparation of specimens of CaOstabilized ZrO2 by slip casting from ethanol-based suspensions. The preparation of Y2O3-ZrO2 compositions by slip casting from aqueous suspension is also reported. A Y2O3 partially stabilized ZrO2 powder was used as a starting material. The densities of the cast specimens were measured from the volume and weight, and those of the sintered specimens were measured by a liquid displacement technique using distilled water. The concentation of the suspension strongly affects the relative density of the cast specimen and the firing shrinkage of the sintered specimen, while the relative density of the sintered specimen is independent of the concentration of the suspension.

Taguchi, H.; Miyamoto, H.; Takahashi, Y.

1985-02-01

318

Titan Casts Revealing Shadow  

NASA Astrophysics Data System (ADS)

A rare celestial event was captured by NASA's Chandra X-ray Observatory as Titan -- Saturn's largest moon and the only moon in the Solar System with a thick atmosphere -- crossed in front of the X-ray bright Crab Nebula. The X-ray shadow cast by Titan allowed astronomers to make the first X-ray measurement of the extent of its atmosphere. On January 5, 2003, Titan transited the Crab Nebula, the remnant of a supernova explosion that was observed to occur in the year 1054. Although Saturn and Titan pass within a few degrees of the Crab Nebula every 30 years, they rarely pass directly in front of it. "This may have been the first transit of the Crab Nebula by Titan since the birth of the Crab Nebula," said Koji Mori of Pennsylvania State University in University Park, and lead author on an Astrophysical Journal paper describing these results. "The next similar conjunction will take place in the year 2267, so this was truly a once in a lifetime event." Animation of Titan's Shadow on Crab Nebula Animation of Titan's Shadow on Crab Nebula Chandra's observation revealed that the diameter of the X-ray shadow cast by Titan was larger than the diameter of its solid surface. The difference in diameters gives a measurement of about 550 miles (880 kilometers) for the height of the X-ray absorbing region of Titan's atmosphere. The extent of the upper atmosphere is consistent with, or slightly (10-15%) larger, than that implied by Voyager I observations made at radio, infrared, and ultraviolet wavelengths in 1980. "Saturn was about 5% closer to the Sun in 2003, so increased solar heating of Titan may account for some of this atmospheric expansion," said Hiroshi Tsunemi of Osaka University in Japan, one of the coauthors on the paper. The X-ray brightness and extent of the Crab Nebula made it possible to study the tiny X-ray shadow cast by Titan during its transit. By using Chandra to precisely track Titan's position, astronomers were able to measure a shadow one arcsecond in diameter, which corresponds to the size of a dime as viewed from about two and a half miles. Illustration of Crab, Titan's Shadow and Chandra Illustration of Crab, Titan's Shadow and Chandra Unlike almost all of Chandra's images which are made by focusing X-ray emission from cosmic sources, Titan's X-ray shadow image was produced in a manner similar to a medical X-ray. That is, an X-ray source (the Crab Nebula) is used to make a shadow image (Titan and its atmosphere) that is recorded on film (Chandra's ACIS detector). Titan's atmosphere, which is about 95% nitrogen and 5% methane, has a pressure near the surface that is one and a half times the Earth's sea level pressure. Voyager I spacecraft measured the structure of Titan's atmosphere at heights below about 300 miles (500 kilometers), and above 600 miles (1000 kilometers). Until the Chandra observations, however, no measurements existed at heights in the range between 300 and 600 miles. Understanding the extent of Titan's atmosphere is important for the planners of the Cassini-Huygens mission. The Cassini-Huygens spacecraft will reach Saturn in July of this year to begin a four-year tour of Saturn, its rings and its moons. The tour will include close flybys of Titan that will take Cassini as close as 600 miles, and the launching of the Huygens probe that will land on Titan's surface. Chandra's X-ray Shadow of Titan Chandra's X-ray Shadow of Titan "If Titan's atmosphere has really expanded, the trajectory may have to be changed." said Tsunemi. The paper on these results has been accepted and is expected to appear in a June 2004 issue of The Astrophysical Journal. Other members of the research team were Haroyoski Katayama (Osaka University), David Burrows and Gordon Garmine (Penn State University), and Albert Metzger (JPL). Chandra observed Titan from 9:04 to 18:46 UT on January 5, 2003, using its Advanced CCD Imaging Spectrometer instrument. NASA's Marshall Space Flight Center, Huntsville, Ala., manages the Chandra program for the Office of Space Science, NASA Headquarters,

2004-05-01

319

Influence of hydroxypropylmethylcellulose addition and homogenization conditions on properties and ageing of corn starch based films.  

PubMed

Edible films based on corn starch, hydroxypropyl methylcellulose (HPMC) and their mixtures were prepared by using two different procedures to homogenize the film forming dispersions (rotor-stator and rotor-stator plus microfluidizer). The influence of both HPMC-starch ratio and the homogenization method on the structural, optical, tensile and barrier properties of the films was analysed. The ageing of the films was also studied by characterizing them after 5 weeks' storage. Starch re-crystallization in newly prepared and stored films was analysed by means of X-ray diffraction. HPMC-corn starch films showed phase separation of polymers, which was enhanced when microfluidization was applied to the film forming dispersion. Nevertheless, HPMC addition inhibited starch re-crystallization during storage, giving rise to more flexible films at the end of the period. Water barrier properties of starch films were hardly affected by the addition of HPMC, although oxygen permeability increased due to its poorer oxygen barrier properties. PMID:24750773

Jiménez, Alberto; Fabra, María José; Talens, Pau; Chiralt, Amparo

2012-06-20

320

Oxide-based method of making compound semiconductor films and making related electronic devices  

DOEpatents

A method for forming a compound film includes the steps of preparing a source material, depositing the source material on a base and forming a preparatory film from the source material, heating the preparatory film in a suitable atmosphere to form a precursor film, and providing suitable material to said precursor film to form the compound film. The source material includes oxide-containing particles including Group IB and IIIA elements. The precursor film includes non-oxide Group IB and IIIA elements. The compound film includes a Group IB-IIIA-VIA compound. The oxides may constitute greater than about 95 molar percent of the Group IB elements and greater than about 95 molar percent of the Group IIIA elements in the source material. Similarly, non-oxides may constitute greater than about 95 molar percent of the Group IB elements and greater than about 95 molar percent of the Group IIIA elements in the precursor film. The molar ratio of Group IB to Group IIIA elements in the source material may be greater than about 0.6 and less than about 1.0, or substantially greater that 1.0, in which case this ratio in the compound film may be reduced to greater than about 0.6 and less than about 1.0. The source material may be prepared as an ink from particles in powder form. The oxide-containing particles may include a dopant, as may the compound film. Compound films including a Group IIB-IVA-VA compound may be substituted using appropriate substitutions in the method. The method, also, is applicable to fabrication of solar cells and other electronic devices.

Kapur, Vijay K. (Tarzana, CA); Basol, Bulent M. (Manhattan Beach, CA); Leidholm, Craig R. (Woodland Hills, CA); Roe, Robert A. (Glendale, CA)

2000-01-01

321

Steel castings by the electroslag casting technique. [CF8M  

SciTech Connect

ELectroslag casting facilities in Canada and the United States were reviewed. Several valve body castings of 2-1/4 Cr-1 Mo, 9 Cr-1 Mo, and 18% Cr-8% Ni(Mo) steels were made at the University of British Columbia facility. These castings were examined for surface finish, chemical segregation, and macrostructure in the as-cast condition and after various heat treatments. Castings were subjected to tensile, Charpy impact, and creep testing. Results of these tests were compared with similar data on wrought material and sand castings.

Sikka, V.K.; Mitchell, A.

1984-01-01

322

3D printing technique applied to rapid casting  

Microsoft Academic Search

Purpose – The purpose of this paper is to verify the feasibility and evaluate the dimensional accuracy of two rapid casting (RC) solutions based on 3D printing technology: investment casting starting from 3D-printed starch patterns and the ZCast process for the production of cavities for light-alloys castings. Design\\/methodology\\/approach – Starting from the identification and design of a benchmark, technological prototypes

Elena Bassoli; Andrea Gatto; Luca Iuliano; Maria Grazia Violante

2007-01-01

323

Design and modeling of a PZT thin film based piezoelectric micromachined ultrasonic transducer (PMUT)  

E-print Network

The design and modelling framework for a piezoelectric micromachined ultrasonic transducer (PMUT) based on the piezoelectric thin film deposition of lead zirconate titanate (PZT) is defined. Through high frequency vibration ...

Smyth, Katherine Marie

2012-01-01

324

Biomimetic, Polymeric Transistor-based Biosensor Technology  

E-print Network

casting uniform, monodisperse films of PbSe onto their test dies.casting the viscous solution ( ?600 cP) onto silicon and pyrex wafer diescasting the germanium nanoparticles. Once films on the the test die

Cheng, Jim Chih-Min

2009-01-01

325

Fabrication and nano-imprintabilities of Zr-, Pd- and Cu-based glassy alloy thin films  

NASA Astrophysics Data System (ADS)

With the aim of investigating nano-imprintability of glassy alloys in a film form, Zr49Al11Ni8Cu32, Pd39Cu29Ni13P19 and Cu38Zr47Al9Ag6 glassy alloy thin films were fabricated on Si substrate by a magnetron sputtering method. These films exhibit a very smooth surface, a distinct glass transition phenomenon and a large supercooled liquid region of about 80 K, which are suitable for imprinting materials. Moreover, thermal nano-imprintability of these obtained films is demonstrated by using a dot array mold with a dot diameter of 90 nm. Surface observations revealed that periodic nano-hole arrays with a hole diameter of 90 nm were successfully imprinted on the surface of these films. Among them, Pd-based glassy alloy thin film indicated more precise pattern imprintability, namely, flatter residual surface plane and sharper hole edge. It is said that these glassy alloy thin films, especially Pd-based glassy alloy thin film, are one of the promising materials for fabricating micro-machines and nano-devices by thermal imprinting.

Takenaka, Kana; Saidoh, Noriko; Nishiyama, Nobuyuki; Inoue, Akihisa

2011-03-01

326

Three-dimensional registration of synchrotron radiation-based micro-computed tomography images with advanced laboratory micro-computed tomography data from murine kidney casts  

NASA Astrophysics Data System (ADS)

Malfunction of oxygen regulation in kidney and liver may lead to the pathogenesis of chronic diseases. The underlying mechanisms are poorly understood. In kidney, it is hypothesized that renal gas shunting from arteries to veins eliminates excess oxygen. Such shunting is highly dependent on the structure of the renal vascular network. The vascular tree has so far not been quantified under maintenance of its connectivity as three-dimensional imaging of the vessel tree down to the smallest capillaries, which in mouse model are smaller than 5 ?m in diameter, is a challenging task. An established protocol uses corrosion casts and applies synchrotron radiation-based micro-computed tomography (SR?CT), which provides the desired spatial resolution with the necessary contrast. However, SR?CT is expensive and beamtime access is limited. We show here that measurements with a phoenix nanotomrm (General Electric, Wunstorf, Germany) can provide comparable results to those obtained with SR?CT, except for regions with small vessel structures, where the signal-to-noise level was significantly reduced. For this purpose the nanotom®m measurement was compared with its corresponding measurement acquired at the beamline P05 at PETRA III at DESY, Hamburg, Germany.

Thalmann, Peter; Hieber, Simone E.; Schulz, Georg; Deyhle, Hans; Khimchenko, Anna; Kurtcuoglu, Vartan; Olgac, Ufuk; Marmaras, Anastasios; Kuo, Willy; Meyer, Eric P.; Beckmann, Felix; Herzen, Julia; Ehrbar, Stefanie; Müller, Bert

2014-09-01

327

Formation of thin film Tl-based high-Tc? superconducting oxides from amorphous alloy precursors  

E-print Network

and satisfying. John Charles Williams TABLE OF CONTENTS ABSTRACT. ACKNOWLEDGMENTS. TABLE OF CONTENTS. LIST OF TABLES. LIST OF FIGURES. I. INTRODUCTION. 1v v vu1 A. Properties of Perovskites and Copper-Oxide Superconductors. . . . . . . . . 2 1.... Fundamental Properties. 2. Perovskite Crystal Structure. 3. Perovskite Crystal Structure Modifications 4, Structure of Thallate Superconductors . . B. Thallium-based Thin Film Superconductors. . . . 1. Tl-based Thin Film Production Methods. . . . 2...

Williams, John Charles

2012-06-07

328

Laser-Based Growth of Nanostructured Thin Films  

NASA Astrophysics Data System (ADS)

The development of powerful, pulsed lasers with immense power has drastically changed our perception of light-matter interactions and opened new ways of implementing laser sources for the growth and processing of nanostructured materials, making Pulsed Laser Deposition (PLD) as one of the most important techniques in the nanotechnology era. In this work, we describe the main parts of a PLD system and the basic physical processes involved, as well as some laser processes for microstructural control of the grown materials. In order to establish firm understanding of the PLD processes, three case studies are presented as examples: (a) External Control of Ablated Species and Application to Tetrahedral Amorphous Carbon (ta-C) Films, (b) Self-assembled nanoparticles (NPs) into dielectric-matrix films and superlattices, (c) Controlling of the atomic structure and nanostructure of intermetallic and glassy films.

Patsalas, P.

329

High power storage system based on thin film solid ionics  

NASA Astrophysics Data System (ADS)

Thin film insertion cathodes obtained in the In-Se system and with a Hall mobility up to 50 sq cm (V sub s) have been measured on annealed films. Electrochemical lithium intercalation has been performed and shows that a plateau appears at 1.8V. The redox stability range has been determined by cyclic voltametry for different preparation conditions of the films. Lithium solid state hybrid systems using borate glasses as electrolyte and lamellar compounds as intercalated electrodes have been tested from the point of view of storage applications. The secondary prototype built with a composite electrode including NiPS3, carbon and powdered electrolyte have been set up and checked. Both thermodynamic and kinetic parameters are given under high power storage conditions.

Balkanski, M.; Julien, C.

1988-02-01

330

Metal-organic chemical vapor deposition of cadmium oxide-based transparent conductors: Precursor design, film growth, and film characterization  

NASA Astrophysics Data System (ADS)

The growing importance of cadmium containing thin films and the desire for their efficient deposition has necessitated the development of high performance MOCVD precursors. To this end, a series of low-melting, and thermally-stable cadmium MOCVD precursors has been synthesized, characterized, and implemented in the growth of highly conductive and transparent CdO-based thin films. One member of the series, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N-diethyl-N ', N'-dimethyl-ethylenediamine)cadmium(II), Cd(hfa)2(N,N-DE-N' ,N'-DMEDA), represents a particularly significant improvement over previously available Cd precursors owing to its low melting point, and robust thermal stability. This precursor will allow careful control of composition and growth rates in complex cadmium-containing oxide systems owing to the elimination of sintering effects detrimental to reproducible growth with solid precursors. Materials with high electrical conductivity and optical transparency are needed for future flat panel display, solar energy, and other opto-electronic technologies. High quality Cd1-xInxO films with been deposited utilizing our new class of MOCVD precursors. The x = 0.05 film, with conductivity of 17,000 S/cm, carrier mobility of 70 cm2/V·s, and wide visible region optical transparency window considerably exceed the corresponding parameters for commercial indium-tin oxide (ITO). A detailed understanding of the fundamental aspects of charge transport in degenerate semiconductors is of great interest. In order to elucidate the importance of individual scattering mechanisms in TCO materials, high-quality CdO films were grown by MOCVD in parallel on glass and single-crystal MgO (100) between 300°C and 412°C. Enhanced mobilities observed for highly biaxially textured films grown on MgO (100) vs. glass are attributed, on the basis of DC charge transport measurements and microstructure analysis, to a reduction in neutral impurity scattering and/or to a more densely packed grain microstructure. Although single grained films grown on MgO (100) exhibit greater mobilities than analogues with discrete ˜100 nm grains and similar texture, this effect is attributed, on the basis of charge transport and Hall effect measurements as well as optical reflectivity analysis to small differences in carrier concentration, rather than to a reduction in grain boundary scattering. Conductivities and mobilities as high as 11,000 S/cm and 307 cm2/V·s, respectively, are obtained for epitaxial single-grained CdO films grown in situ on MgO (100).

Metz, Andrew William

2003-07-01

331

Crosslinking and composition influence the surface properties, mechanical stiffness and cell reactivity of collagen-based films.  

E-print Network

This study focuses on determining the effect of varying the composition and crosslinking of collagen-based films on their physical properties and interaction with myoblasts. Films composed of collagen or gelatin and crosslinked with a carbodiimide...

Grover, CN; Gwynne, JH; Pugh, N; Hamaia, S; Farndale, RW; Best, Serena Michelle; Cameron, Ruth Elizabeth

2012-07-09

332

Physical properties of emulsion-based hydroxypropyl methylcellulose films: effect of their microstructure.  

PubMed

The initial characteristics of emulsions and the rearrangement of the oil droplets in the film matrix during film drying, which defines its microstructure, has an important role in the physical properties of the emulsion-based films. The objective of this work was to study the effect of the microstructure (two droplet size distributions) and stability (with or without surfactant) of HPMC oil-in-water emulsions over physical properties of HPMC emulsion-based edible films. HPMC was used to prepare sunflower oil-in-water emulsions containing 0.3 or 1.0% (w/w) of oil with or without SDS, as surfactant, using an ultrasonic homogenizer. Microstructure, rheological properties and stability of emulsions (creaming) were measured. In addition, microstructure, coalescence of oil droplets, surface free energy, optical and mechanical properties and water vapor transfer of HPMC films were evaluated. Image analysis did not show differences among droplet size distributions of emulsions prepared at different oil contents; however, by using SDS the droplet size distributions were shifted to lower values. Volume mean diameters were 3.79 and 3.77 ?m for emulsions containing 0.3 and 1.0% without surfactant, respectively, and 2.72 and 2.71 ?m for emulsions with SDS. Emulsions formulated with 1.0% of oil presented higher stability, with almost no change during 5 and 3 days of storage, for emulsions with and without SDS, respectively. Internal and surface microstructure of emulsion-based films was influenced by the degree of coalescence and creaming of the oil droplets. No effect of microstructure over the surface free energy of films was found. The incorporation of oil impaired the optical properties of films due to light scattering of light. Addition of oil and SDS decreased the stress at break of the emulsion-based films. The replace of HPMC by oil and SDS produce a lower "amount" of network structure in the films, leading to a weakening of their structure. The oil content and SDS addition had an effect over the microstructure and physical properties of HPMC-based emulsions which lead to different microstructures during film formation. The way that oil droplets were structured into the film had an enormous influence over the physical properties of HPMC films. PMID:22840052

Zúñiga, R N; Skurtys, O; Osorio, F; Aguilera, J M; Pedreschi, F

2012-10-01

333

High-energy-density sol-gel thin film based on neat 2-cyanoethyltrimethoxysilane.  

PubMed

Hybrid organic-inorganic sol-gel dielectric thin films from a neat 2-cyanoethyltrimethoxysilane (CNETMS) precursor have been fabricated and their permittivity, dielectric strength, and energy density characterized. CNETMS sol-gel films possess compact, polar cyanoethyl groups and exhibit a relative permittivity of 20 at 1 kHz and breakdown strengths ranging from 650 V/?m to 250 V/?m for film thicknesses of 1.3 to 3.5 ?m. Capacitors based on CNETMS films exhibit extractable energy densities of 7 J/cm(3) at 300 V/?m, as determined by charge-discharge and polarization-electric field measurements, as well as an energy extraction efficiency of ~91%. The large extractable energy resulting from the linear dielectric polarization behavior suggests that CNETMS films are promising sol-gel materials for pulsed power applications. PMID:23427818

Kim, Yunsang; Kathaperumal, Mohanalingam; Smith, O'Neil L; Pan, Ming-Jen; Cai, Ye; Sandhage, Kenneth H; Perry, Joseph W

2013-03-13

334

Kittel law in BiFeO? ultrathin films: a first-principles-based study.  

PubMed

A first-principles-based effective Hamiltonian is used to investigate the thickness dependency of the size of straight-walled domains in ultrathin films made of the multiferroic BiFeO? (BFO) material. It is found that the Kittel law is followed, as in ferroelectric or ferromagnetic films. However, an original real-space decomposition of the different energetic terms of this effective Hamiltonian allows the discovery that the microscopic origins of such a law in BFO films dramatically differ from those in ferroelectric or ferromagnetic films. In particular, interactions between tilting of oxygen octahedra around the domain walls and magnetoelectric couplings near the surface (and away from the domain walls) play an important role in the observance of the Kittel law in the studied BFO films. PMID:21230868

Prosandeev, S; Lisenkov, S; Bellaiche, L

2010-10-01

335

Atomic Oxygen Sensors Based on Nanograin ZnO Films Prepared by Pulse Laser Deposition  

SciTech Connect

High-quality nanograin ZnO thin films were deposited on c-plane sapphire (Al{sub 2}O{sub 3}) substrates by pulse laser deposition (PLD). Scanning electron microscopy (SEM) and x-ray diffraction (XRD) were used to characterize the samples. The structural and morphological properties of ZnO films under different deposition temperature have been investigated before and after atomic oxygen (AO) treatment. XRD has shown that the intensity of the (0 0 2) peak increases and its FWHM value decreases after AO treatment. The AO sensing characteristics of nano ZnO film also has been investigated in a ground-based atomic oxygen simulation facility. The results show that the electrical conductivity of nanograin ZnO films decreases with increasing AO fluence and that the conductivity of the films can be recovered by heating.

Wang Yunfei; Chen Xuekang; Li Zhonghua; Zheng Kuohai; Wang Lanxi; Feng Zhanzu; Yang Shengsheng [National Key Laboratory of Vacuum and Cryogenics Technology and Physics, Lanzhou Institute of Physics, Lanzhou 730000 (China)

2009-01-05

336

Fabrication of TiO2-based composite films by sequential ion implantation and subsequent annealing  

NASA Astrophysics Data System (ADS)

A special method for fabricating a series of TiO2-based composite catalyst film is presented. There are two steps in this method. Firstly, two kinds of elements are sequentially implanted into the substrate. Then, the implanted samples are annealed in oxygen atmosphere. This method involves a solid phase growth process, which can be successfully used to prepare noble metal nanoparticles modified TiO2 film (Au NP-TiO2), metallic (Fe, V) and non-metallic (N) doped TiO2, and narrow-width band gap heterojunctions (Fe2O3-TiO2). These TiO2-based composite catalyst films show good crystallinity and stability, easy catalyst immobilization and recycling in photocatalytic experiments. In addition, the detailed growth processes and mechanisms of these TiO2-based composite films were systematically studied.

Liu, Dan; Ren, Feng; Cai, Guang-Xu; Liu, Yi-Chao; Hong, Meng-Qing; Ying, Jian-Jian; Liu, Yong; Zhou, Juan; Wu, Wei; Xiao, Xiang-Heng; Jiang, Chang-Zhong

2014-04-01

337

Gafchromic EBT2 film dosimetry in reflection mode with a novel plan-based calibration method  

SciTech Connect

Purpose:A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: (a) is it possible to employ this dosimetric system in reflection mode; (b) if so, can the methods used in transmission mode also be used in reflection mode; (c) is it possible to obtain accurate absolute dose measurements with Gafchromic EBT2 films; (d) which calibration method should be followed; (e) which calibration models should be used; and (f) does three-color channel dosimetry offer a significant improvement over single channel dosimetry. The purpose of this paper is to help clarify these questions. Methods: In this study, films were scanned in reflection mode, the effect of surrounding film was evaluated and the feasibility of EBT2 film dosimetry in reflection mode was studied. EBT2's response homogeneity has been reported to lead to excessive dose uncertainties. To overcome this problem, a new plan-based calibration method was implemented. Plan-based calibration can use every pixel and each of the three color channels of the scanned film to obtain the parameters of the calibration model. A model selection analysis was conducted to select lateral correction and sensitometric curve models. The commonly used calibration with fragments was compared with red-channel plan-based calibration and with three-channel plan-based calibration. Results: No effect of surrounding film was found in this study. The film response inhomogeneity in EBT2 films was found to be important not only due to differences in the fog but also due to differences in sensitivity. The best results for lateral corrections were obtained using absolute corrections independent of the dose. With respect to the sensitometric curves, an empirical polynomial fit of order 4 was found to obtain results equivalent to a gamma-distributed single hit model based on physical assumptions. Three-channel dosimetry was found to be substantially superior to red-channel dosimetry. Conclusions: Reflection mode with Gafchromic EBT2 radiochromic film was found to be a viable alternative to transmission mode. The same methods that are used in transmission mode can be followed in reflection mode. A novel plan-based method was developed for calibration and multichannel dosimetry. This novel method offers increased robustness against film response inhomogeneities and reduces considerably the time required for calibration.

Mendez, I.; Hartman, V.; Hudej, R.; Strojnik, A.; Casar, B. [Department of Medical Physics, Institute of Oncology Ljubljana, Zaloska cesta 2, Ljubljana 1000 (Slovenia)

2013-01-15

338

Memory switches based on metal oxide thin films  

NASA Technical Reports Server (NTRS)

MnO.sub.2-x thin films (12) exhibit irreversible memory switching (28) with an OFF/ON resistance ratio of at least about 10.sup.3 and the tailorability of ON state (20) resistance. Such films are potentially extremely useful as a connection element in a variety of microelectronic circuits and arrays (24). Such films provide a pre-tailored, finite, non-volatile resistive element at a desired place in an electric circuit, which can be electrically turned OFF (22) or disconnected as desired, by application of an electrical pulse. Microswitch structures (10) constitute the thin film element, contacted by a pair of separate electrodes (16a, 16b) and have a finite, pre-selected ON resistance which is ideally suited, for example, as a programmable binary synaptic connection for electronic implementation of neural network architectures. The MnO.sub.2-x microswitch is non-volatile, patternable, insensitive to ultraviolet light, and adherent to a variety of insulating substrates (14), such as glass and silicon dioxide-coated silicon substrates.

Ramesham, Rajeshuni (Inventor); Thakoor, Anilkumar P. (Inventor); Lambe, John J. (Inventor)

1990-01-01

339

Verification of Gamma Knife extend system based fractionated treatment planning using EBT2 film  

SciTech Connect

Purpose: This paper presents EBT2 film verification of fractionated treatment planning with the Gamma Knife (GK) extend system, a relocatable frame system for multiple-fraction or serial multiple-session radiosurgery.Methods: A human head shaped phantom simulated the verification process for fractionated Gamma Knife treatment. Phantom preparation for Extend Frame based treatment planning involved creating a dental impression, fitting the phantom to the frame system, and acquiring a stereotactic computed tomography (CT) scan. A CT scan (Siemens, Emotion 6) of the phantom was obtained with following parameters: Tube voltage—110 kV, tube current—280 mA, pixel size—0.5 × 0.5 and 1 mm slice thickness. A treatment plan with two 8 mm collimator shots and three sectors blocking in each shot was made. Dose prescription of 4 Gy at 100% was delivered for the first fraction out of the two fractions planned. Gafchromic EBT2 film (ISP Wayne, NJ) was used as 2D verification dosimeter in this process. Films were cut and placed inside the film insert of the phantom for treatment dose delivery. Meanwhile a set of films from the same batch were exposed from 0 to 12 Gy doses for calibration purposes. An EPSON (Expression 10000 XL) scanner was used for scanning the exposed films in transparency mode. Scanned films were analyzed with inhouse written MATLAB codes.Results: Gamma index analysis of film measurement in comparison with TPS calculated dose resulted in high pass rates >90% for tolerance criteria of 1%/1 mm. The isodose overlay and linear dose profiles of film measured and computed dose distribution on sagittal and coronal plane were in close agreement.Conclusions: Through this study, the authors propose treatment verification QA method for Extend frame based fractionated Gamma Knife radiosurgery using EBT2 film.

Natanasabapathi, Gopishankar; Bisht, Raj Kishor [Gamma Knife Unit, Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029 (India)] [Gamma Knife Unit, Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029 (India)

2013-12-15

340

Bipolar strain sensor based on an ultra-thin film of single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

A bipolar strain sensor based on an ultra-thin film of single-walled carbon nanotubes (SWNTs) has been fabricated. First, a random network of SWNTs was grown on a Si substrate with thermal oxide by using chemical vapor deposition and then transferred to a transparent poly(dimethyl)siloxane (PDMS) film. A mechanical load was applied by pressing the PDMS-SWNT film with a blunt micrometer tip, and its electrical conductance was found to decrease linearly with increasing pressure. Upward bending of the flexible PDMS-SWNT film was found to yield increases in conductance whereas downward bending of the film was found to result in decreases in the conductance. We modeled the SWNT network on the PDMS film with a two-dimensional percolation system, and found that the increases (decreases) in the conductance of the film upon bending could be explained in terms of stick-density changes in the 2-D percolation system. Finally, because PDMS swells with certain organic vapors, a PDMS-SWNT film can be used as a chemical sensor for volatile organic compounds. Unlike for three-dimensional composites of SWNTs and polymers, the bipolar response upon bending and simple fabrication process for the system introduced here mean that it is an attractive candidate for tactile and motion sensor applications.

Park, Dong-Won; Kim, Beom Soo; Park, Serin; Choi, Won-Jin; Yang, Cheol-Soo; Lee, Jeong-O.

2014-02-01

341

Characterization of edible emulsified films with low affinity to water based on kefiran and oleic acid.  

PubMed

New edible composite films based on kefiran and oleic acid (OA) at the ratio of 15, 25, and 35% (w/w) were prepared using emulsification with the aim of improving their water vapour barrier and mechanical properties. Film-forming solutions were characterized in terms of rheological properties and particle-size distribution. The impact of the incorporation of OA into the film matrix was studied by investigating the physical, mechanical, and thermal properties of the films. The water vapour permeability (WVP) of the emulsified films was reduced by approximately 33% by adding OA. The mechanical properties of kefiran films were also affected by adding OA: tensile strength was diminished, and elongation increased considerably. Differential scanning calorimetry showed that the glass transition temperature (T(g)) of the kefiran film was -16°C and was not considerably affected by adding OA. Therefore, OA could be incorporated into these films for some food-technology applications that need a low affinity toward water. PMID:21640752

Ghasemlou, Mehran; Khodaiyan, Faramarz; Oromiehie, Abdulrasoul; Yarmand, Mohammad Saeid

2011-10-01

342

Near infrared reflectance spectroscopy for the fast identification of PVC-based films  

E-print Network

First published as an Advance Article on the web 19th June 2001 Near infrared (NIR) reflectance spectroscopy was used to develop a non-destructive and rapid qualitative method for the analysis of plastic films used by the pharmaceutical industry for blistering. Three types of films were investigated: 250 mm PVC [poly(vinyl chloride)] films, 250 mm PVC films coated with 40 g m 22 of PVDC [poly(vinylidene dichloride)] and 250 mm PVC films coated with 5 g m 22 of TE (Thermoelast) and 90 g m 22 of PVDC. Three analyses were carried out using different pre-treatment options and a PLS (partial least squares) algorithm. Each analysis was aimed at identifying one type of film and rejecting all types of false sample (different thickness, colour or layer). True and false samples from four plastics manufacturers were included in the calibration sets in order to obtain robust methods that were suitable regardless of the supplier. Specificity was demonstrated by testing validation sets against the methods. The tests showed 0 % of type I (false negative identification) and 1 % of type II errors (false positive identification) for the PVC method, 13 and 3%, respectively, for the PVC–PVDC method and no error for the PVC–TE–PVDC method. Type II errors, mostly due to the slight sensitivity of the methods to film thickness, are easily corrected by simple thickness measurements. This study demonstrates that NIR spectroscopy is an excellent tool for the identification of PVC-based films. The

Magali Laasonen; A Jukka Rantanen; B Tuulikki Harmia-pulkkinen; C Erik Michiels

2001-01-01

343

First-principles studies of hydrogen interaction with ultrathin Mg and Mg-based alloy films  

NASA Astrophysics Data System (ADS)

The search for technologically and economically viable storage solutions for hydrogen fuel would benefit greatly from research strategies that involve systematic property tuning of potential storage materials via atomic-level modification. Here, we use first-principles density-functional theory to investigate theoretically the structural and electronic properties of ultrathin Mg films and Mg-based alloy films and their interaction with atomic hydrogen. Additional delocalized charges are distributed over the Mg films upon alloying them with 11.1% of Al or Na atoms. These extra charges contribute to enhance the hydrogen binding strength to the films. We calculated the chemical potential of hydrogen in Mg films for different dopant species and film thickness, and we included the vibrational degrees of freedom. By comparing the chemical potential with that of free hydrogen gas at finite temperature (T) and pressure (P), we construct a hydrogenation phase diagram and identify the conditions for hydrogen absorption or desorption. The formation enthalpies of metal hydrides are greatly increased in thin films, and in stark contrast to its bulk phase, the hydride state can only be stabilized at high P and T (where the chemical potential of free H2 is very high). Metal doping increases the thermodynamic stabilities of the hydride films and thus significantly helps to reduce the required pressure condition for hydrogen absorption from H2 gas. In particular, with Na alloying, hydrogen can be absorbed and/or desorbed at experimentally accessible T and P conditions.

Yoon, Mina; Weitering, Hanno H.; Zhang, Zhenyu

2011-01-01

344

[Analysis of spectral characteristics of oil film on water based on wavelet transform].  

PubMed

The diagnostic features are the basis to detect and characterize the oil film on water through optical remote sensing. This work shows the results of lab spectral measurements of light diesel oil with thickness ranged 1.0 - 127 microm. A wavelet transform were performed to the reflectance, and the singularity (388-393 nm) was explored as the indicators of oil film thickness. The results indicate that the reflectance of light diesel oil film is higher than that of water in the range from 350-2 500 nm. There is a reflectance peak near 388 nm when the thickness of oil film is larger than 6 microm, however, no distinguished features could be recognized when oil films were thinner than 6 microm. The wavelet coefficients of the fifth decomposition level by applying Daubechies 4 (db4) mother wavelets proved successful for identifying the singularity of oil film's reflectance spectra and its accurate position. With the thickness lager than 6 microm, the detail coefficients performed an abrupt change within the range of 388-393 nm, and became more violent while oil films' thickness increased. This research demonstrated that oil films on water with different thickness could be distinguished based on wavelet detail coefficients, with important implications for detection of oils on water using UV and short wave optical remote sensing. PMID:23016354

Li, Ying; Liu, Bing-Xin; Li, Bao-Yu; Chen, Duo

2012-07-01

345

[Studies on application of pure titanium for cast plate].  

PubMed

Pure titanium produced by a commercial pure titanium casting system was studied for use as a cast plate for clinical application. The mechanical properties, elemental analysis, castability, adaptability of pure titanium and adhesion to denture base resin were investigated. The interfacial zone of the pure titanium castings was composed of a layered structure obtained by reaction with phosphate bonded Al2O3/SiO2 investment material. Vicher's hardness at 100 microns thick from the surface was higher than that in the inner part by oxidation. Cast pure titanium showed tensile strength, elongation and hardness close to those of the type III or IV dental gold alloy. The castability of pure titanium was lower than that of Co-Cr alloy and pure titanium castings also had large casting defects. Adaptability between pure titanium cast plate and the working model was satisfactory when reversible hydrocolloid impression material was used with heating-bath treatment in the refractory model. The tensile and compressive shear bonding strength of pure titanium to heat-curing or self-curing resin were similar to that of the Co-Cr alloy, and surface treatment using a solution containing 2-vol% 3-methacryloxypropyltrimethoxysilane produced a higher bonding strength than non-treatment, MKV treatment and 4-META treatment. These findings suggest that pure titanium castings produced by this system have suitable mechanical properties, adaptability and adhesion to denture base resin, and is available for cast plate in clinical application. PMID:2134765

Sakai, M

1990-06-01

346

CAST FLOOR WITH VIEW OF TORPEDO LADLE (BENEATH CAST FLOOR) ...  

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

CAST FLOOR WITH VIEW OF TORPEDO LADLE (BENEATH CAST FLOOR) AND KEEPERS OF THE CAST HOUSE FLOOR, S.L. KIMBROUGH AND DAVID HOLMES. - U.S. Steel, Fairfield Works, Blast Furnace No. 8, North of Valley Road, West of Ensley-Pleasant Grove Road, Fairfield, Jefferson County, AL

347

Hickey, C8206_all casts Hickey, C8206_all casts, page 1  

E-print Network

Hickey, C8206_all casts Hickey, C8206_all casts, page 1 #12;Hickey, C8206_all casts Hickey, C8206_all casts, page 2 #12;Hickey, C8206_all casts Hickey, C8206_all casts, page 3 #12;Hickey, C8206_all casts Hickey, C8206_all casts, page 4 #12;Hickey, C8206_all casts Hickey, C8206_all casts, page 5 #12

Hickey, Barbara

348

Preparation and characterization of sodium caseinate films reinforced with cellulose derivatives  

Microsoft Academic Search

Edible composite films, based on glycerol-plasticized sodium caseinate (SC) and either carboxymethyl cellulose (CMC) or cellulose acetate (CA) fibers, were respectively prepared by suspension casting. The effects of mixing SC with very low amounts (up to 3wt%) of CMC or CA were systematically investigated through changes in morphology, surface hydrophilicity, moisture sorption, water vapor permeability, opacity, dynamic mechanical response and

Mariana Pereda; Guillermina Amica; Ilona Rácz; Norma E. Marcovich

2011-01-01

349

Intense pulsed light treatment of cadmium telluride nanoparticle-based thin films.  

PubMed

The search for low-cost growth techniques and processing methods for semiconductor thin films continues to be a growing area of research; particularly in photovoltaics. In this study, electrochemical deposition was used to grow CdTe nanoparticulate based thin films on conducting glass substrates. After material characterization, the films were thermally sintered using a rapid thermal annealing technique called intense pulsed light (IPL). IPL is an ultrafast technique which can reduce thermal processing times down to a few minutes, thereby cutting production times and increasing throughput. The pulses of light create localized heating lasting less than 1 ms, allowing films to be processed under atmospheric conditions, avoiding the need for inert or vacuum environments. For the first time, we report the use of IPL treatment on CdTe thin films. X-ray diffraction (XRD), optical absorption spectroscopy (UV-Vis), scanning electron microscopy (SEM) and room temperature photoluminescence (PL) were used to study the effects of the IPL processing parameters on the CdTe films. The results found that optimum recrystallization and a decrease in defects occurred when pulses of light with an energy density of 21.6 J cm(-2) were applied. SEM images also show a unique feature of IPL treatment: the formation of a continuous melted layer of CdTe, removing holes and voids from a nanoparticle-based thin film. PMID:24635698

Dharmadasa, Ruvini; Lavery, Brandon; Dharmadasa, I M; Druffel, Thad

2014-04-01

350

Solution-processed flexible transparent conductors based on carbon nanotubes and silver grid hybrid films  

NASA Astrophysics Data System (ADS)

In a simple, cost-effective, and solution-based process, a thin-film of single-walled carbon nanotubes is hybridized on a PET film which has been patterned with solution self-assembled Ag nanoparticles. Such a flexible and transparent electrode exhibits a sheet resistance down to ~5.8 ? sq-1 at ~83.7% optical transmittance. The hybrid films are stable under ambient conditions and offer excellent bendability.In a simple, cost-effective, and solution-based process, a thin-film of single-walled carbon nanotubes is hybridized on a PET film which has been patterned with solution self-assembled Ag nanoparticles. Such a flexible and transparent electrode exhibits a sheet resistance down to ~5.8 ? sq-1 at ~83.7% optical transmittance. The hybrid films are stable under ambient conditions and offer excellent bendability. Electronic supplementary information (ESI) available: Experimental details, performance of graphene-Ag hybrid and met-SWNT-Ag hybrid films. See DOI: 10.1039/c3nr06386k

Wang, Jing; Zhang, Jintao; Sundramoorthy, Ashok Kumar; Chen, Peng; Chan-Park, Mary B.

2014-04-01

351

Investigating the nature of graphene-based films prepared by vacuum filtration of graphene dispersions.  

PubMed

Though the graphene-based films prepared by vacuum filtration of graphene dispersions can be well and easily prepared so far and show great prospects in conductive, transparent, and flexible devices and coatings, the nature of these films has been rarely investigated. In order to reveal how graphene flakes constitute these films, herein we prepared a thin graphene-based film by vacuum filtering graphene dispersions and characterized the film by diverse techniques. Microscopic analyses evidenced the layer structure nature of the film. Raman spectra, transmission electron microscopy, and X-ray diffraction results indicate that the film is neither graphene nor graphite, but intrinsically a graphene block constituted by numerous graphene flakes which are randomly stacked. Though aggregation of graphene flakes happens in the filtration process, the aggregation is not a process to drive graphene flakes stacked in Bernal AB style to form bulk graphite. The adjoining graphene flakes are poorly coupled, likely due to the interlayer adventitious impurities introduced from liquid-phase processing. PMID:24757968

Yi, Min; Liang, Shuaishuai; Liu, Lei; Shen, Zhigang; Zheng, Yiting; Zhang, Xiaojing; Ma, Shulin

2014-07-01

352

DIVISION 04 MASONRY 04720 CAST STONE  

E-print Network

DIVISION 04 ­ MASONRY _____________________________________________________________ 04720 CAST STONE A. Design Considerations 1. Cast stone shall comply with ASTM C1364, Standard Specification for Cast Stone. 2. Care must be taken in the design of individual units of cast stone, working within

353

New understanding of hardening mechanism of TiN/SiNx-based nanocomposite films  

PubMed Central

In order to clarify the controversies of hardening mechanism for TiN/SiNx-based nanocomposite films, the microstructure and hardness for TiN/SiNx and TiAlN/SiNx nanocomposite films with different Si content were studied. With the increase of Si content, the crystallization degree for two series of films firstly increases and then decreases. The microstructural observations suggest that when SiNx interfacial phase reaches to a proper thickness, it can be crystallized between adjacent TiN or TiAlN nanocrystallites, which can coordinate misorientations between nanocrystallites and grow coherently with them, resulting in blocking of the dislocation motions and hardening of the film. The microstructure of TiN/SiNx-based nanocomposite film can be characterized as the nanocomposite structure with TiN-based nanocrystallites surrounded by crystallized SiNx interfacial phase, which can be denoted by nc-TiN/c-SiNx model ('c’ before SiNx means crystallized) and well explain the coexistence between nanocomposite structure and columnar growth structure within the TiN/SiNx-based film. PMID:24134611

2013-01-01

354

Low k thin films based on rf plasma-polymerized aniline  

NASA Astrophysics Data System (ADS)

Thermally stable materials with low dielectric constant (k<3.9) are being hotly pursued. They are essential as interlayer dielectrics/intermetal dielectrics in integrated circuit technology, which reduces parasitic capacitance and decreases the RC time constant. Most of the currently employed materials are based on silicon. Low k films based on organic polymers are supposed to be a viable alternative as they are easily processable and can be synthesized with simpler techniques. It is known that the employment of ac/rf plasma polymerization yields good quality organic thin films, which are homogenous, pinhole free and thermally stable. These polymer thin films are potential candidates for fabricating Schottky devices, storage batteries, LEDs, sensors, super capacitors and for EMI shielding. Recently, great efforts have been made in finding alternative methods to prepare low dielectric constant thin films in place of silicon-based materials. Polyaniline thin films were prepared by employing an rf plasma polymerization technique. Capacitance, dielectric loss, dielectric constant and ac conductivity were evaluated in the frequency range 100 Hz 1 MHz. Capacitance and dielectric loss decrease with increase of frequency and increase with increase of temperature. This type of behaviour was found to be in good agreement with an existing model. The ac conductivity was calculated from the observed dielectric constant and is explained based on the Austin Mott model for hopping conduction. These films exhibit low dielectric constant values, which are stable over a wide range of frequencies and are probable candidates for low k applications.

Saravanan, S.; Mathai, C. Joseph; Venkatachalam, S.; Anantharaman, M. R.

2004-06-01

355

CAT-CVD process and its application to preparation of Si-based thin films  

SciTech Connect

This is to review the present understanding on Cat-CVD (catalytic chemical vapor deposition) or hot wire CVD. Firstly, the deposition mechanism in Cat-CVD process is briefly mentioned along with key issues such as the effect of heat radiation and a method to avoid contamination from the catalyzer. Secondly, the properties of Cat-CVD Si-based thin films such as amorphous silicon (a-Si), polycrystalline silicon (poly-Si) and silicon nitride (SiN{sub x}) films are demonstrated, and finally, the feasibility of such films for industrial application is discussed.

Matsumura, Hideki; Masuda, Atsushi; Izumi, Akira

1999-07-01

356

Measurement of Adhesion Strength of DLC Film Prepared by Utilizing Plasma-Based Ion Implantation  

NASA Astrophysics Data System (ADS)

High-adhesion diamond-like carbon (DLC) film was prepared by a hybrid process of plasma-based ion implantation and deposition using superimposed RF and high-voltage pulses. The adhesion strength of DLC film on a stainless steel (SUS304) was enhanced by the carbon ion implantation to the substrate. Furthermore, ion implantation of mixed carbon and silicon led to considerable enhancement of adhesion strength above the resin glue strength. The adhesion strength of DLC film on the aluminum alloy (A-5052) was improved above the resin glue strength only by the carbon ion implantation to the substrate.

Oka, Yoshihiro; Yatsuzuka, Mitsuyasu

357

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

358

Chemical sensing employingpH sensitive emeraldine base thin film for carbon dioxide detection  

NASA Astrophysics Data System (ADS)

Respiration, or CO2 evolution, is a universal indicator for all the biological activities. Among many potential applications, the measurement of CO2 evolution has been found to be a rapid and nondestructive means for examining microbial contamination of food. The sensor developed in this work consists of a thin emeraldine base-polyaniline (EB-PAni) film. In the first half of the project the effect of carbon dioxide over the conductivity of a composite film of emeraldine base polyaniline and poly(vinyl alcohol) in N-methyl pyrrolidone (NMP) respectively was tested. Argon gas or mixture of argon and 5% CO2 were circulated through the glass cell containing the polymer film deposited on interdigitated electrode and exposed to specific humidity levels fixed by aqueous supersaturated salt solutions. In the second half of the project, a thin emeraldine base film in NMP was directly deposited on interdigitated electrode and the respective sensor inserted in water. Carbonic acid solutions of various pHs were generated by bubbling specific mixtures of carbon dioxide and argon. Conductivity measurements were performed by impedance spectroscopy throughout the project. The sensing mechanism is based on intermediate stages of the transformation of the emeraldine base polyaniline to a conductive salt type (ES-PAni). This EB-ES transformation is the consequence of the exposure of EB-PAni to a protonic acid and is accompanied by a change in the conductivity of the polymer film. Carbonic acid, unfortunately, is a very weak acid and is unable to induce a conductivity change, but the intermediate steps that predetermine this transformation are detected by impedance spectroscopy even when the overall conductivity of the film is unchanged. The composite thin film developed in the first part of the project showed poor sensing characteristics: limited dynamic range, drift, instability and slow time response. However, the sensor design employed in the second half of this work, coupled with impedance spectroscopy measurements, revealed valuable information about conduction mechanisms at pH levels were the overall conductivity of the film remained unchanged. Typical impedance spectra for the emeraldine thin films for a frequency sweep between 3.2 E7 to 1 Hz shows a single semicircle. The overall conductivity of the film (5x10-4 S/cm) does not change when CO 2 is bubbled through the water in which the sensor is immersed, but an additional semicircle starts to appear at low (less than 200 Hz) frequency corresponding to lowering the pH of the solution below 5.0. The original semicircle diminishes in size but maintains its initial peak frequency. The EB film is very sensitive to pH changes, therefore an additional semicircle appears in unpurified argon gas due to the reduction of the pH of water solution to 4.65. The same mechanism is displayed in hydrochloric acid solutions of various pH. The formation of the second semicircle depends on the initial conductivity of the emeraldine base film, a film displaying an initial conductivity of 4.8 x 10-3 S/cm forming the second semicircle at a pH of 5.85. The appearance of the second semicircle is most likely due to a preferential protonation in the insulating matrix of the polymer film. The overall conductivity of the film increases when the level of protonation in the insulating portion of the film reached a level close to the protonation level in the scattered metallic islands, allowing the electron-hopping mechanism to became active. The sensor output is stable and reproducible even after 11 months passed from the polymer film deposition.

Irimia-Vladu, Mihai

359

Hydrogen gas sensor based on palladium and yttrium alloy ultrathin film.  

PubMed

Compared with the other hydrogen sensors, optical fiber hydrogen sensors based on thin films exhibits inherent safety, small volume, immunity to electromagnetic interference, and distributed remote sensing capability, but slower response characteristics. To improve response and recovery rate of the sensors, a novel reflection-type optical fiber hydrogen gas sensor with a 10 nm palladium and yttrium alloy thin film is fabricated. The alloy thin film shows a good hydrogen sensing property for hydrogen-containing atmosphere and a complete restorability for dry air at room temperature. The variation in response value of the sensor linearly increases with increased natural logarithm of hydrogen concentration (ln[H(2)]). The shortest response time and recovery response time to 4% hydrogen are 6 and 8 s, respectively. The hydrogen sensors based on Pd(0.91)Y(0.09) alloy ultrathin film have potential applications in hydrogen detection and measurement. PMID:23278019

Yi, Liu; You-Ping, Chen; Han, Song; Gang, Zhang

2012-12-01

360

Planar plasmonic terahertz waveguides based on periodically corrugated metal films  

NASA Astrophysics Data System (ADS)

We demonstrate that a one-dimensional periodically corrugated metal film can be used to create planar terahertz (THz) waveguides. The periodic corrugation is in the form of rectangular blind holes (i.e. holes that do not completely perforate the metal film) that are fabricated using a multilayer construction. The approach allows for the creation of structures in which the hole depth can be more than four times the hole width. This is necessary to achieve tightly confined THz guided-wave modes. We find that the modes can be modeled using an effective cavity resonance model and that the mode properties depend sensitively on the depth of corrugation. We use numerical simulations to validate the experimental results. We also highlight the differences between simulations that incorporate idealized input parameters and our experimental measurements. Using these data, we fabricate and characterize a Y-splitter to demonstrate the utility of this approach.

Kumar, Gagan; Pandey, Shashank; Cui, Albert; Nahata, Ajay

2011-03-01

361

Magnesium die casting properties  

SciTech Connect

Numerous innovative applications of magnesium alloy die castings have recently been introduced by the automotive industry. This is the result of dedicated long-term development involving end users, die casters, and equipment and material suppliers. It is realized that superior product performance can only by obtained by fully exploiting the synergy of optimum design, processing route, and material selection. A particularly good example is provided by the rapid growth of magnesium die casting applications for safety parts, requiring high fracture toughness. In such applications, the favorable intrinsic properties of magnesium die casting alloys have been exploited to an extent which was formerly not believed possible. Introduction of new alloys such as AM50 has further expanded the range of properties attainable. Standard references on alloy properties do not reflect these developments, and there is a strong need for updated information. These data, reflecting recent advances in alloy chemistry and die casting technology, should be more current than those available in most sources of physical and mechanical properties.

NONE

1995-08-01

362

Cool Cast Facts  

MedlinePLUS

... may tell you to cover it with a plastic bag while you shower or you can get a special waterproof sleeve to cover it. Depending on where your cast or splint is on your body, you may find it easier to take a ...

363

Thin film ZnO based bulk acoustic mode filters  

Microsoft Academic Search

We have used thin film ZnO bulk mode resonators on an acoustically reflecting solid glass substrate to produce a variety of filters in the 1-3 GHz frequency bands. Power handling is large (>2W). Overall filter dimensions are very small (~1 mm), while lithography requirements are undemanding (>10 ?m). A range of ladder filters has been produced with an average rejection

C. W. Seabury; P. H. Kobrin; R. Addison; D. P. Havens

1997-01-01

364

Mix/Cast Contamination Control  

NASA Technical Reports Server (NTRS)

Presented is a training handbook for Mix/Cast Contamination Control; a part of a series of training courses to qualify access to Mix/Cast facilities. Contents: List Contamination Control Requirements; Identify foreign objects debris (FOD), Control Areas and their guidelines; Describe environmental monitoring; List Contamination Control Initiatives; Describe concern for Controlled Materials; Identify FOD Controlled Areas in Mix/Cast.

Wallentine, M.

2005-01-01

365

Martensitic transformation and shape memory behavior in sputter-deposited TiNi-base thin films  

Microsoft Academic Search

Since 1990, Ti?Ni and Ti?Ni?X (X=Cu, Pd, Hf) thin films have been made by sputtering. The motivation for fabricating sputter-deposited TiNi-base shape memory alloy thin films originates from the great demand for the development of powerful microactuators which can drive micromachines, because actuation force and displacement are greatest in shape memory alloys amongst many actuator materials. Stable shape memory effect

S Miyazaki; A Ishida

1999-01-01

366

A silane-based electroactive film prepared in an imidazolium chloroaluminate molten salt  

Microsoft Academic Search

Electrochemical oxidation of Ph[sub 3]SiCl (Ph = phenyl) in the room-temperature molten salt AlCl[sub 3]:EMICl (EMICl = 1-ethyl-3-methylimidazolium chloride) results in the formation of an adherent electroactive film on the surface of solid electrodes. The film is reversibly oxidized and reduced in the molten salt and is conducting when in the oxidized state. Based on x-ray photoelectron spectroscopy analysis, the

Richard T. Carlin; R. A. Osteryoung

1994-01-01

367

Micro-Bubble Phenomenon in Nanoscale Water-based Lubricating Film Induced by External Electric Field  

Microsoft Academic Search

The effect of an external electric field (EEF) on water-based thin films has been investigated. Some micro-bubbles emerging\\u000a around the edge of the Hertz contact region in the films of deioned water and polyethylene glycols (PEG) aqueous solutions\\u000a have been observed. A higher EEF intensity is needed at which the micro-bubbles begin to emerge after the EEF is applied on

Guoxin Xie; Jianbin Luo; Shuhai Liu; Chenhui Zhang; Xinchun Lu

2008-01-01

368

Recent progress in carbon nanotube-based flexible transparent conducting film  

Microsoft Academic Search

Flexible transparent conducting films (TCFs) were fabricated on a PET substrate by various methods using carbon nanotubes dispersed in organic or water-based solution. Thin multi-walled carbon nanotubes, double-walled carbon nanotubes, and single-walled carbon nanotubes were used to compare the performance for TCFs. Optimal design rules for types of nanotubes, surfactants, the degree of dispersion, and film preparation methods were discussed.

Hong-Zhang Geng; Ki Kang Kim; Young Hee Lee

2008-01-01

369

Temperature distribution in SFCLs based on Au\\/YBCO films during quenches  

Microsoft Academic Search

We investigated temperature distribution in SFCLs based on Au\\/YBa2Cu3O7 (YBCO). SFCLs were fabricated by patterning Au\\/YBCO thin films grown on sapphire substrates into meander lines by photolithography. A gold film grown on the back side of the substrate was patterned into a meander line, and used as a thermometer. The front meander line was subjected to simulated AC fault currents,

Hye-Rim Kim; Jungwook Sim; Ok-Bae Hyun

2006-01-01

370

Inexpensive color evaluation of dye-based pressure-sensitive films for plantar studies  

Microsoft Academic Search

Dye-based pressure-sensitive films are advantageous in plantar pressure studies due to their ease of use, cost-effectiveness, and ability to produce measurements within the shoe. To circumvent the use of proprietary equipment and software to relate the dye-stained film to load, an alternative approach of using a conventional flatbed scanner and generic image processing software is attempted here instead. The technique

T. W. Ng; W. K. Yeong

2005-01-01

371

Cylindrical PVF2 film based fiber optic phase modulator - Phase shift nonlinearity and frequency response  

NASA Astrophysics Data System (ADS)

A new cylindrical coil configuration for polyvinylidene flouride (PVF2) film based fiber optic phase modulator is studied for the frequency response and nonlinearity of phase shift at the resonance frequency. This configuration, hitherto unapproached for PVF2 film modulators, offers resonance at well defined, controllable and higher frequencies than possible for the flat-strip configuration. Two versions of this configuration are presented that differ strongly in both the resonance frequency and the phase shift nonlinearity coefficient.

Sudarshanam, V. S.; Claus, Richard O.

1993-03-01

372

Factors Affecting the Moisture Permeability of Lipid-Based Edible Films: A Review  

Microsoft Academic Search

Referee: Dr. Aris Gennadios, Senior Manager, Materials Science, Research and Development, Banner Pharmacaps Inc., P.O. Box 2210, 27261-2210, 4125 Premier Drive, High Point, NC 27265-8144 Moisture transfers inside food products could be controlled or limited by the use of edible films. These are usually based on hydrophobic substances such as lipids to improve barrier efficiency. Water permeability of films is

Valérie Morillon; Frédéric Debeaufort; Geneviève Blond; Martine Capelle; Andrée Voilley

2002-01-01

373

Development and characterization of an edible composite film based on chitosan and virgin coconut oil with improved moisture sorption properties.  

PubMed

An edible composite film was prepared from an emulsion system based on chitosan and virgin coconut oil (VCO). The effect of incorporation of VCO was evaluated at various concentrations and the optimum concentration was chosen based on resultant changes in the properties of the film. Addition of VCO in film forming solution resulted in increase in film thickness and marginal reduction in film transparency. Compatibility of VCO with chitosan was better at lower concentration of VCO as indicated by the microstructure of composite film in scanning electron micrographs. Phase separation was evident at higher level of oil incorporation and the optimal oil/chitosan ratio was determined to be at 0.5 to 1 mL/g chitosan. Furthermore, chemical interaction took place between VCO and chitosan as revealed by Fourier transform infrared spectroscopy data. Even though control chitosan films exhibited superior gas barrier properties, composite film with optimum VCO concentration revealed better mechanical and moisture sorption properties. PMID:23464980

Binsi, P K; Ravishankar, C N; Srinivasa Gopal, T K

2013-04-01

374

Evaluation of cast creep occurring during simulated clubfoot correction.  

PubMed

The Ponseti method is a widely accepted and highly successful conservative treatment of pediatric clubfoot involving weekly manipulations and cast applications. Qualitative assessments have indicated the potential success of the technique with cast materials other than standard plaster of Paris. However, guidelines for clubfoot correction based on the mechanical response of these materials have yet to be investigated. The current study sought to characterize and compare the ability of three standard cast materials to maintain the Ponseti-corrected foot position by evaluating cast creep response. A dynamic cast testing device, built to model clubfoot correction, was wrapped in plaster of Paris, semi-rigid fiberglass, and rigid fiberglass. Three-dimensional motion responses to two joint stiffnesses were recorded. Rotational creep displacement and linearity of the limb-cast composite were analyzed. Minimal change in position over time was found for all materials. Among cast materials, the rotational creep displacement was significantly different (p < 0.0001). The most creep displacement occurred in the plaster of Paris (2.0°), then the semi-rigid fiberglass (1.0°), and then the rigid fiberglass (0.4°). Torque magnitude did not affect creep displacement response. Analysis of normalized rotation showed quasi-linear viscoelastic behavior. This study provided a mechanical evaluation of cast material performance as used for clubfoot correction. Creep displacement dependence on cast material and insensitivity to torque were discovered. This information may provide a quantitative and mechanical basis for future innovations for clubfoot care. PMID:23636764

Cohen, Tamara L; Altiok, Haluk; Wang, Mei; McGrady, Linda M; Krzak, Joseph; Graf, Adam; Tarima, Sergey; Smith, Peter A; Harris, Gerald F

2013-08-01

375

Leaching-resistant carrageenan-based colorimetric oxygen indicator films for intelligent food packaging.  

PubMed

Visual oxygen indicators can give information on the quality and safety of packaged food in an economic and simple manner by changing color based on the amount of oxygen in the packaging, which is related to food spoilage. In particular, ultraviolet (UV)-activated oxygen indicators have the advantages of in-pack activation and irreversibility; however, these dye-based oxygen indicator films suffer from dye leaching upon contact with water. In this work, we introduce carrageenans, which are natural sulfated polysaccharides, to develop UV-activated colorimetric oxygen indicator films that are resistant to dye leakage. Carrageenan-based indicator films were fabricated using redox dyes [methylene blue (MB), azure A, and thionine], a sacrificial electron donor (glycerol), an UV-absorbing photocatalyst (TiO2), and an encapsulation polymer (carrageenan). They showed even lower dye leakage in water than conventional oxygen indicator films, owing to the electrostatic interaction of anionic carrageenan with cationic dyes. The MB/TiO2/glycerol/carrageenan oxygen indicator film was successfully bleached upon UV irradiation, and it regained color very rapidly in the presence of oxygen compared to the other waterproof oxygen indicator films. PMID:24979322

Vu, Chau Hai Thai; Won, Keehoon

2014-07-23

376

Enhancements in Magnesium Die Casting Impact Properties  

SciTech Connect

The need to produce lighter components in transportation equipment is the main driver in the increasing demand for magnesium castings. In many automotive applications, components can be made of magnesium or aluminum. While being lighter, often times the magnesium parts have lower impact and fatigue properties than the aluminum. The main objective of this study was to identify potential improvements in the impact resistance of magnesium alloys. The most common magnesium alloys in automotive applications are AZ91D, AM50 and AM60. Accordingly, these alloys were selected as the main candidates for the study. Experimental quantities of these alloys were melted in an electrical furnace under a protective atmosphere comprising sulfur hexafluoride, carbon dioxide and dry air. The alloys were cast both in a permanent mold and in a UBE 315 Ton squeeze caster. Extensive evaluation of tensile, impact and fatigue properties was conducted at CWRU on permanent mold and squeeze cast test bars of AZ91, AM60 and AM50. Ultimate tensile strength values between 20ksi and 30ksi were obtained. The respective elongations varied between 25 and 115. the Charpy V-notch impact strength varied between 1.6 ft-lb and 5 ft-lb depending on the alloy and processing conditions. Preliminary bending fatigue evaluation indicates a fatigue limit of 11-12 ksi for AM50 and AM60. This is about 0.4 of the UTS, typical for these alloys. The microstructures of the cast specimens were investigated with optical and scanning electron microscopy. Concomitantly, a study of the fracture toughness in AM60 was conducted at ORNL as part of the study. The results are in line with values published in the literature and are representative of current state of the art in casting magnesium alloys. The experimental results confirm the strong relationship between aluminum content of the alloys and the mechanical properties, in particular the impact strength and the elongation. As the aluminum content increases from about 5% in AM50 to over 9% in AZ91, more of the intermetallic Mg17Al12 is formed in the microstructure. For instance, for 15 increase in the aluminum content from AM50 to AM60, the volume fraction of eutectic present in the microstructure increases by 35%! Eventually, the brittle Mg17Al12 compound forms an interconnected network that reduces ductility and impact resistance. The lower aluminum in AM50 and AM60 are therefore a desirable feature in applications that call for higher impact resistance. Further improvement in impact resistance depends on the processing condition of the casting. Sound castings without porosity and impurities will have better mechanical properties. Since magnesium oxidizes readily, good melting and metal transfer practices are essential. The liquid metal has to be protected from oxidation at all times and entrainment of oxide films in the casting needs to be prevented. In this regard, there is evidence that us of vacuum to evacuate air from the die casting cavity can improve the quality of the castings. Fast cooling rates, leading to smaller grain size are beneficial and promote superior mechanical properties. Micro-segregation and banding are two additional defect types often encountered in magnesium alloys, in particular in AZ91D. While difficult to eliminate, segregation can be minimized by careful thermal management of the dies and the shot sleeve. A major source of segregation is the premature solidification in the shot sleeve. The primary solid dendrites are carried into the casting and form a heterogeneous structure. Furthermore, during the shot, segregation banding can occur. The remedies for this kind of defects include a hotter shot sleeve, use of insulating coatings on the shot sleeve and a short lag time between pouring into the shot sleeve and the shot.

David Schwam; John F. Wallace; Yulong Zhu; Srinath Viswanathan; Shafik Iskander

2000-06-30

377

Temperature dependence of resistive switching behaviors in resistive random access memory based on graphene oxide film  

NASA Astrophysics Data System (ADS)

We reported resistive switching behaviors in the resistive random access memory (RRAM) devices based on the different annealing temperatures of graphene oxide (GO) film as active layers. It was found that the resistive switching characteristics of an indium tin oxide (ITO)/GO/Ag structure have a strong dependence on the annealing temperature of GO film. When the annealing temperature of the GO film was 20 °C, the devices showed typical write-once-read-many-times (WORM) type memory behaviors, which have good memory performance with a higher ON/OFF current ratio (˜104), the higher the high resistance state (HRS)/low resistance state (LRS) ratio (˜105) and stable retention characteristics (>103 s) under lower programming voltage (-1 V and -0.5 V). With the increasing annealing temperature of GO film, the resistive switching behavior of RRAM devices gradually weakened and eventually disappeared. This phenomenon could be understood by the different energy level distributions of the charge traps in GO film, and the different charge injection ability from the Ag electrode to GO film, which is caused by the different annealing temperatures of the GO film.

Yi, Mingdong; Cao, Yong; Ling, Haifeng; Du, Zhuzhu; Wang, Laiyuan; Yang, Tao; Fan, Quli; Xie, Linghai; Huang, Wei

2014-05-01

378

Temperature dependence of resistive switching behaviors in resistive random access memory based on graphene oxide film.  

PubMed

We reported resistive switching behaviors in the resistive random access memory (RRAM) devices based on the different annealing temperatures of graphene oxide (GO) film as active layers. It was found that the resistive switching characteristics of an indium tin oxide (ITO)/GO/Ag structure have a strong dependence on the annealing temperature of GO film. When the annealing temperature of the GO film was 20 °C, the devices showed typical write-once-read-many-times (WORM) type memory behaviors, which have good memory performance with a higher ON/OFF current ratio (?10(4)), the higher the high resistance state (HRS)/low resistance state (LRS) ratio (?10(5)) and stable retention characteristics (>10(3) s) under lower programming voltage (-1 V and -0.5 V). With the increasing annealing temperature of GO film, the resistive switching behavior of RRAM devices gradually weakened and eventually disappeared. This phenomenon could be understood by the different energy level distributions of the charge traps in GO film, and the different charge injection ability from the Ag electrode to GO film, which is caused by the different annealing temperatures of the GO film. PMID:24739543

Yi, Mingdong; Cao, Yong; Ling, Haifeng; Du, Zhuzhu; Wang, Laiyuan; Yang, Tao; Fan, Quli; Xie, Linghai; Huang, Wei

2014-05-01

379

The X-ray Telescope of CAST  

E-print Network

The Cern Axion Solar Telescope (CAST) is in operation and taking data since 2003. The main objective of the CAST experiment is to search for a hypothetical pseudoscalar boson, the axion, which might be produced in the core of the sun. The basic physics process CAST is based on is the time inverted Primakoff effect, by which an axion can be converted into a detectable photon in an external electromagnetic field. The resulting X-ray photons are expected to be thermally distributed between 1 and 7 keV. The most sensitive detector system of CAST is a pn-CCD detector combined with a Wolter I type X-ray mirror system. With the X-ray telescope of CAST a background reduction of more than 2 orders off magnitude is achieved, such that for the first time the axion photon coupling constant g_agg can be probed beyond the best astrophysical constraints g_agg < 1 x 10^-10 GeV^-1.

M. Kuster; H. Bräuninger; S. Cébrian; M. Davenport; C. Elefteriadis; J. Englhauser; H. Fischer; J. Franz; P. Friedrich; R. Hartmann; F. H. Heinsius; D. H. H. Hoffmann; G. Hoffmeister; J. N. Joux; D. Kang; K. Königsmann; R. Kotthaus; T. Papaevangelou; C. Lasseur; A. Lippitsch; G. Lutz; J. Morales; A. Rodríguez; L. Strüder; J. Vogel; K. Zioutas

2007-02-22

380

Production and characterization of films from cotton stalk xylan.  

PubMed

Composite film production based on cotton stalk xylan was studied, and the mechanical and physical properties of the films formed were investigated. Xylan and lignin were separated from cellulose by alkali extraction and, then, lignin was removed using ethanol washing. Self-supporting continuous films could not be produced using pure cotton stalk xylan. However, film formation was achieved using 8-14% (w/w) xylan without complete removal of lignin during xylan isolation. Keeping about 1% lignin in xylan (w/w) was determined to be sufficient for film formation. Films were produced by casting the film-forming solutions, followed by solvent evaporation in a temperature (20 degrees C) and relative humidity (40%) controlled environment. The elastic modulus and hypothetical coating strength of the films obtained by using 8% xylan were significantly different from the ones containing 10-14% xylan. The water vapor transfer rates (WVTR) decreased with increasing xylan concentration, which made the films thicker. The glycerol addition as an additional plasticizer resulting in more stretchable films having higher WVTR and lower water solubility values. As a result, film production was successfully achieved from xylan, which was extracted from an agricultural waste (cotton stalk), and the film-forming effect of lignin on pure xylan has been demonstrated. PMID:18038981

Goksu, Emel I; Karamanlioglu, Mehlika; Bakir, Ufuk; Yilmaz, Levent; Yilmazer, Ulku

2007-12-26

381

Precision cast vs. wrought superalloys  

NASA Technical Reports Server (NTRS)

While cast polycrystalline superalloys recommend themselves in virtue of better 'buy-to-fly' ratios and higher strengthening gamma-prime volume fractions than those of wrought superalloys, the expansion of their use into such critical superalloy applications as gas turbine hot section components has been slowed by insufficient casting process opportunities for microstructural control. Attention is presently drawn, however, to casting process developments facilitating the production of defect-tolerant superalloy castings having improved fracture reliability. Integrally bladed turbine wheel and thin-walled turbine exhaust case near-net-shape castings have been produced by these means.

Tien, J. K.; Borofka, J. C.; Casey, M. E.

1986-01-01

382

Magnetoresistance of CuCrO2-based delafossite films  

Microsoft Academic Search

Oxides with the delafossite structure (space group Rbar 3m) are of interest as wide-bandgap semiconductors, and as multiferroics. Well oriented c-axis films of CuCrO2 and CuCr0.9Mg0.1O2 have been produced on c-cut sapphire by PLD at elevated temperatures (650 °C). The lattice parameters for CuCrO2 are a = 299.6 pm and c = 1719.7 pm. The end member is insulating at

M. O'Sullivan; P. Stamenov; J. Alaria; M. Venkatesan; J. M. D. Coey

2010-01-01

383

AMCC casting development, volume 2  

NASA Technical Reports Server (NTRS)

PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

1995-01-01

384

Gafchromic EBT2 film dosimetry in reflection mode with a novel plan-based calibration method  

E-print Network

Purpose: A dosimetric system formed by Gafchromic EBT2 radiochromic film and Epson Expression 10000XL flatbed scanner was commissioned for dosimetry. In this paper, several open questions concerning the commissioning of radiochromic films for dosimetry were addressed: a) is it possible to employ this dosimetric system in reflection mode; b) if so, can the methods used in transmission mode also be used in reflection mode; c) is it possible to obtain accurate absolute dose measurements with Gafchromic EBT2 films; d) which calibration method should be followed; e) which calibration models should be used; f) does three-color channel dosimetry offer a significant improvement over single channel dosimetry. The purpose of this paper is to help clarify these questions. Conclusions: Reflection mode with Gafchromic EBT2 radiochromic film was found to be a viable alternative to transmission mode. The same methods that are used in transmission mode can be followed in reflection mode. A novel plan-based method was develop...

Mendez, I; Hudej, R; Strojnik, A; Casar, B

2014-01-01

385

Surface morphology and optical properties of thin films of thiophene-based binary blends  

NASA Astrophysics Data System (ADS)

We report on the relationship between optical and morphological properties of thin films of a blend of thiophene-based monomer and a diamine derivative. This system is of interest as it gives rise to white emission, due to the formation of exciplex energy levels in the solid state. The photoluminescence emission has been collected for different relative concentrations of the two blend components, and the film topography has been mapped correspondingly by means of atomic force microscopy. Along with a complex evolution of the film surface morphology, a significant variation of the emission properties has been observed upon change of the blend composition. In particular, the intensity of the broad low-energy exciplex band turns out to be affected by a balance of two factors, namely, the extension of homogeneous blend film areas, and their effective concentration.

Salerno, Marco; Blyth, Robert Ian Renton; Thompson, Julie; Cingolani, Roberto; Gigli, Giuseppe

2005-07-01

386

Solution-based assembly of conductive gold film on flexible polymer substrates.  

PubMed

Conductive films of gold were assembled on flexible polymer substrates such as Kapton and polyethylene using a solution-based process. The polymer substrates were modified by using argon plasma and subsequent coupling of silanes with amino- or mercapto- terminal groups. These modified surfaces were examined by X-ray photoelectron spectroscopy and contact angle measurements. Colloidal gold was assembled onto the silane-modified surface from solution. The gold particles are attached to the surface by covalent interactions with the thiol or amine group. Formation of a conductive film is achieved by increasing the coverage of gold by using a "seeding" method to increase the size of the attached gold particles. Field emission scanning electron microscopy was used to follow the growth of the film. The surface resistance of the films, measured using a four-point probe, was about 1 Omega/sq. PMID:15379520

Supriya, Lakshmi; Claus, Richard O

2004-09-28

387

Multifunctional thick-film structures based on spinel ceramics for environment sensors  

NASA Astrophysics Data System (ADS)

Temperature sensitive thick films based on spinel-type NiMn2O4-CuMn2O4-MnCo2O4 manganites with p- and p+-types of electrical conductivity and their multilayer p+-p structures were studied. These thick-film elements possess good electrophysical characteristics before and after long-term ageing test at 170 °C. It is shown that degradation processes connected with diffusion of metallic Ag into film grain boundaries occur in one-layer p-and p+-conductive films. Some part of the p+-p structures were of high stability, the relative electrical drift being no more than 1 %.

Vakiv, M.; Hadzaman, I.; Klym, H.; Shpotyuk, O.; Brunner, M.

2011-04-01

388

Influence of emulsifier type and content on functional properties of polysaccharide lipid-based edible films.  

PubMed

This study investigates the effect of different types of surfactant (glycerol monostearate, Tween 60, and Tween 80) on water vapor permeability (WVP), tensile strength (TS), percentage elongation at breaking (E), and structure of an emulsified edible film composed of cornstarch, methylcellulose, and cocoa butter or soybean oil. Factorial designs at two levels were used to analyze the effect of emulsifier (EM) and lipid content on the functional properties of film. Results showed that the effects of independent variables on WVP, TS, and E depend on surfactant and lipid type. The presence of EM significantly decreased the WVP of cocoa butter films but did not improve the barrier or mechanical properties of soybean oil-based film. PMID:15479005

Bravin, Barbara; Peressini, Donatella; Sensidoni, Alessandro

2004-10-20

389

Solution-based synthesis of crystalline silicon thin films from liquid silane inks  

NASA Astrophysics Data System (ADS)

Silicon (Si) dominates the photovoltaics industry and there is a need for new approaches that can significantly reduce fabrication cost. In this context, we report a non-vacuum, solution-based process for the synthesis of crystalline silicon (c-Si) thin films from liquid cyclohexasilane (CHS) in a platform that is readily applicable to large-area flexible devices. UV-polymerization during spin coating leads to the formation of thin films, which were crystallized via thermal and laser annealing. Structural changes in the films were examined using SEM, AFM and Raman spectroscopy. Subsequent chemical annealing through atmospheric-pressure hydrogen plasma treatment led to a four-decade enhancement in film conductivity, which we attribute to a disorder-order transition in a bonded Si network.

Iyer, Ganjigunte R. S.; Guruvenket, S.; Hoey, Justin M.; Anderson, Kenneth J.; Schulz, Douglas L.; Swenson, Orven F.; Elangovan, S.; Boudjouk, P.; Hobbie, Erik K.

2012-02-01

390

Polyaniline Langmuir-Blodgett film based cholesterol biosensor.  

PubMed

Cholesterol oxidase (ChOx) has been covalently linked to Langmuir-Blodgett (LB) monolayers of polyaniline (PANI)-stearic acid (SA) prepared onto indium-tin-oxide (ITO) coated glass plates via glutaraldehyde (Glu) chemistry. These ChOx/Glu/PANI-SA LB film/ITO electrodes have been characterized by FT-IR, cyclic voltammetry, and scanning electron microscopy, respectively. The results of response measurements carried out on these bioelectrodes using linear sweep voltammetry (LSV) reveal linearity from 25 to 400 mg/dL of cholesterol concentration with sensitivity of 88.9 nA mg(-1) dL. The linear regression analysis of bioelectrode reveals standard deviation and correlation coefficient of 0.737 microA and 0.9988, respectively. The low value of the Michaelis-Menten constant of these bioelectrodes obtained as 1.21 mM for the immobilized enzyme indicates increased interaction between ChOx and cholesterol in the PANI-SA LB film. PMID:18001068

Matharu, Zimple; Sumana, G; Arya, Sunil K; Singh, S P; Gupta, Vinay; Malhotra, B D

2007-12-18

391

Friction stir welding of aluminium casting alloys  

Microsoft Academic Search

It has been presented the results of testing of friction stir welding quality in relation to EN AC-43200 (AK9) and EN AC-45000 (AK64) aluminium casting alloys. The test joints were made with the use of the welding machine constructed on the basis of numerically controlled milling machines. The assessment of the joints quality was made basing oneself on the visual

Damian Miara; Adam Pietras

2012-01-01

392

Die Soldering in Aluminium Die Casting  

Microsoft Academic Search

Two types of tests, dipping tests and dip-coating tests were carried out on small steel cylinders using pure aluminum and 380 alloy to investigate the mechanism of die soldering during aluminum die casting. Optical and scanning electron microscopy were used to study the morphology and composition of the phases formed during soldering. A soldering mechanism is postulated based on experimental

Q. Han; E. A. Kenik; S. Viswanathan

2000-01-01

393

CAST: Collaborative Agents for Simulating Teamwork  

Microsoft Academic Search

Psychological studies on teamwork have shown that an effective team often can anticipate information needs of teammates based on a shared mental model. Existing multi-agent models for teamwork are limited in their ability to support proactive information exchange among teammates. To address this issue, we have developed and implemented a multi-agent architecture called CAST that simulates teamwork and supports proactive

John Yen; Jianwen Yin; Thomas R. Ioerger; Michael S. Miller; Dianxiang Xu; Richard A. Volz

2001-01-01

394

Hickey, TT162, Casts 2-5 Hickey, TT162, Casts 2-5, page 1  

E-print Network

Hickey, TT162, Casts 2-5 Hickey, TT162, Casts 2-5, page 1 CTD002 #12;Hickey, TT162, Casts 2-5 Hickey, TT162, Casts 2-5, page 2 CTD002 #12;Hickey, TT162, Casts 2-5 Hickey, TT162, Casts 2-5, page 3 CTD002 #12;Hickey, TT162, Casts 2-5 Hickey, TT162, Casts 2-5, page 4 CTD002 #12;Hickey, TT162, Casts 2

Hickey, Barbara

395

Hickey, TT136, casts 6-10 Hickey, TT136, casts 6-10, page 1  

E-print Network

Hickey, TT136, casts 6-10 Hickey, TT136, casts 6-10, page 1 CTD006 #12;Hickey, TT136, casts 6-10 Hickey, TT136, casts 6-10, page 2 CTD006 #12;Hickey, TT136, casts 6-10 Hickey, TT136, casts 6-10, page 3 CTD006 #12;Hickey, TT136, casts 6-10 Hickey, TT136, casts 6-10, page 4 CTD006 #12;Hickey, TT136, casts

Hickey, Barbara

396

Hickey, TT162, casts 6-7 Hickey, TT162, casts 6-7, page 1  

E-print Network

CTD006 Hickey, TT162, casts 6-7 Hickey, TT162, casts 6-7, page 1 #12;CTD006 Hickey, TT162, casts 6-7 Hickey, TT162, casts 6-7, page 2 #12;CTD006 Hickey, TT162, casts 6-7 Hickey, TT162, casts 6-7, page 3 #12;CTD006 Hickey, TT162, casts 6-7 Hickey, TT162, casts 6-7, page 4 #12;CTD006 Hickey, TT162, casts 6

Hickey, Barbara

397

Hickey, TT136, casts 3-5 Hickey, TT136, casts 3-5, page 1  

E-print Network

Hickey, TT136, casts 3-5 Hickey, TT136, casts 3-5, page 1 CTD003 #12;Hickey, TT136, casts 3-5 Hickey, TT136, casts 3-5, page 2 CTD003 #12;Hickey, TT136, casts 3-5 Hickey, TT136, casts 3-5, page 3 CTD003 #12;Hickey, TT136, casts 3-5 Hickey, TT136, casts 3-5, page 4 CTD003 #12;Hickey, TT136, casts 3

Hickey, Barbara

398

Development of a Hot Tear Indicator for Steel Castings C. Monroe, C. Beckermann  

E-print Network

Development of a Hot Tear Indicator for Steel Castings C. Monroe, C. Beckermann Department, Casting Simulation, Steel Abstract A hot tear indicator based on the physics of solidification, not a full tear predictor. Simulation results for various "T" shaped steel castings show good agreement

Beckermann, Christoph

399

A neural network system for the prediction of process parameters in pressure die casting  

Microsoft Academic Search

In this work an artificial intelligent neural network system is developed to generate the process parameters for the pressure die casting process. The scope of this work includes analysing a physical model of the pressure die casting filling stage based on the governing equations of die cavity filling, and the collection of feasible casting data for the training of the

Prasad K. D. V. Yarlagadda; Eric Cheng Wei Chiang

1999-01-01

400

A new method for casting discrepancy: some results for a phosphate-bonded investment  

Microsoft Academic Search

Objectives: An accurate and realistic casting discrepancy method applicable to base metal alloys has hitherto been lacking. The purpose of this study was to develop a method for determining casting discrepancy free of interference from oxide, slag and surface defects, working under realistic conditions. In addition, a variable was sought that could be used for calibrating the casting process to

E. K.-H. Ho; B. W. Darvell

1998-01-01

401

Comparative Study of 3D Printing Technologies for Rapid Casting of Aluminium Alloy  

Microsoft Academic Search

The purpose of this study is to compare the efficacy of two rapid casting technologies, namely, ZCast process and investment casting based on 3D printing technique of rapid prototyping for casting of aluminium alloy. A standard procedure has been premeditated starting from the identification and design of benchmark. The concept was presented in physical form by producing prototypes to assess

Simranpreet Singh Gill; Munish Kaplas

2009-01-01

402

Converge-Cast with MIMO Luoyi Fu, Yi Qin, Xinbing Wang  

E-print Network

Converge-Cast with MIMO Luoyi Fu, Yi Qin, Xinbing Wang Dept. of Electronic Engineering Shanghai investigates throughput and delay based on a newly predominant traffic pattern, called converge-cast, where schemes under converge-cast for both static and mobile ad hoc networks (MANETs), respectively. In a static

Wang, Xinbing

403

Design for die casting  

Microsoft Academic Search

The purpose of this research was to establish methods and a system for transforming finished (machined) part designs into shapes that are die castable. The major contribution from this work is a consistent and systematic method of analysing the shape of die castings. This research is necessary because computer-aided design\\/manufacturing\\/engineering (CAD\\/CAM\\/CAE) systems are only loosely coupled, making manufacturability analysis very

S. Y. LIOU; R. A. MILLER

1991-01-01

404

Extrusion cast explosive  

DOEpatents

Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

Scribner, K.J.

1985-01-29

405

Extrusion cast explosive  

DOEpatents

Disclosed is an improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants. 1 fig.

Scribner, K.J.

1985-11-26

406

Magnetoresistance of CuCrO2-based delafossite films  

NASA Astrophysics Data System (ADS)

Oxides with the delafossite structure (space group Rbar 3m) are of interest as wide-bandgap semiconductors, and as multiferroics. Well oriented c-axis films of CuCrO2 and CuCr0.9Mg0.1O2 have been produced on c-cut sapphire by PLD at elevated temperatures (650 °C). The lattice parameters for CuCrO2 are a = 299.6 pm and c = 1719.7 pm. The end member is insulating at room temperature with ? gtrsim 1000 ? m whereas the Mg-doped oxide is a degenerate p-type semiconductor with ? approx 1.5 x 10-4 ? m. There is a resistivity anomaly at TN. A large negative magnetoresistance, which reaches its maximum value (approx 300 %) in 14 T at about 2 K, persists throughout the temperature range where magnetic short range order is significant.

O'Sullivan, M.; Stamenov, P.; Alaria, J.; Venkatesan, M.; Coey, J. M. D.

2010-01-01

407

Schottky Solar Cells Based on Colloidal Nancrystal Films  

SciTech Connect

We describe here a simple, all-inorganic metal/NC/metal sandwich photovoltaic (PV) cell that produces an exceptionally large short-circuit photocurrent (>21 mA cm{sup -2}) by way of a Schottky junction at the negative electrode. The PV cell consists of a PbSe NC film, deposited via layer-by-layer (LbL) dip coating that yields an EQE of 55-65% in the visible and up to 25% in the infrared region of the solar spectrum, with a spectrally corrected AM1.5G power conversion efficiency of 2.1%. This NC device produces one of the largest short-circuit currents of any nanostructured solar cell, without the need for sintering, superlattice order or separate phases for electron and hole transport.

Luther, J. M.; Law, M.; Beard, M. C.; Song, Q.; Reese, M. O.; Ellingson, R. J.; Nozik, A. J.

2008-01-01

408

Receiver protecting device based on microstrip structure with high-temperature superconductor film  

NASA Astrophysics Data System (ADS)

New design of an effective device for protection against high-power electromagnetic pulses has been created based on a pair of noninteracting microstrip resonators, which are coupled in the working frequency band via a third resonator based on a thin film of high-temperature superconductor (HTSC) occurring in the superconducting state. Under the action of an electromagnetic pulse with the power above a certain threshold, the HTSC film element passes from the superconducting to normal (high-resistivity) state, thus breaking the coupling between resonators. This leads to power limitation at the device output due to a strong signal reflection from the input.

Belyaev, B. A.; Govorun, I. V.; Leksikov, A. A.; Serzhantov, A. M.

2012-03-01

409

Carboxyl-Ebselen-Based Layer-by-Layer Films as Potential Antithrombotic and Antimicrobial Coatings  

PubMed Central

A carboxyl-ebselen-based layer-by-layer (LbL) film was fabricated by alternatively assembling carboxyl-ebselen immobilized polyethylenimine (e-PEI) and alginate (Alg) onto substrates followed by salt annealing and cross-linking. The annealed films exhibiting significantly improved stability are capable of generating nitric oxide (NO) from endogeneous S-nitrosothiols (RSNOs) in the presence of a reducing agent. The NO generation behaviors of different organoselenium species in solution phase are compared and the annealing mechanism to create stable LbL films is studied in details. An LbL film coated polyurethane catheter is capable of generating physiological levels of NO from RSNOs even after blood soaking for 24 h, indicating potential antithrombotic applications of the coating. Further, the LbL film is also demonstrated to be capable of reducing living bacterial surface attachment and killing a broad spectrum of bacteria, likely through generation of superoxide (O2•?) from oxygen. This type of film is expected to have potential application as an antithrombotic and antimicrobial coating for different biomedical device surfaces. PMID:21794909

Cai, Wenyi; Wu, Jianfeng; Xi, Chuanwu; Ashe, Arthur J.; Mark, E. Meyerhoff

2011-01-01

410

Modeling of casting microstructures and defects  

SciTech Connect

Casting is an ancient art that has been a trial-and-error process for more than 4000 years. To predict the size, shape, and quality of a cast product, casting manufacturers typically cast full-size prototypes. If one part of the process is done incorrectly, the entire process is repeated until an acceptable product is achieved. One way to reduce the time, cost, and waste associated with casting is to use computer modeling to predict not only the quality of a product on the macro- scale, such as distortion and part shape, but also on the micro-scale such as grain defects. Modeling of solidification is becoming increasingly feasible with the advent of parallel computers. There are essentially two approaches to solidification modeling.The first is that of macro-modeling where heat transfer codes model latent heat release during solidification as a constant and based solely on the local temperature. This approach is useful in predicting large scale distortion and final part shape. The second approach, micro-modeling, is more fundamental. The micro-models estimate the latent heat release during solidification using nucleation and grain growth kinetics. Micro-models give insight into cast grain morphology and show promise in the future to predict engineering properties such as tensile strength. The micro-model solidification kinetics can be evaluated using first principles or they can be evaluated using experiments. This work describes an implementation of a micro-model for uranium which uses experimental results to estimate nucleation and growth kinetics.

Shapiro, A.B.; Summers, L.T.; Eckels, D.J.; Sahai, V.

1997-09-26

411

A computational model for defect prediction in shape castings based on the interaction of free surface flow, heat transfer, and solidification phenomena  

Microsoft Academic Search

High-integrity castings require sophisticated design and manufacturing procedures to ensure they are essentially macrodefect\\u000a free. Unfortunately, an important class of such defects—macroporosity, misruns, and pipe shrinkage—are all functions of the\\u000a interactions of free surface flow, heat transfer, and solidication in complex geometries. Because these defects arise as an\\u000a interaction of the preceding continuum phenomena, genuinely predictive models of these defects

S. Bounds; G. Moran; K. Pericleous; M. Cross; T. N. Croft

2000-01-01

412

Structure and transition of eutectic (Mg,Al) 2Ca Laves phase in a die-cast Mg–Al–Ca base alloy  

Microsoft Academic Search

The crystal structure of a eutectic (Mg,Al)2Ca Laves phase in as-cast AXJ530 (Mg–5Al–3Ca–0.15Sr) was identified as C36 by electron diffraction analysis. The C36 phase transformed to C15(Al2Ca) during annealing at 573 K. The orientation relationship for the C15 and C36 phases is reported.

A. Suzuki; N. D. Saddock; J. W. Jones; T. M. Pollock

2004-01-01

413

Study of water vapour permeability of protein and gum-based edible films by a photothermal method  

NASA Astrophysics Data System (ADS)

The water vapour permeability of protein and gum-based edible films was studied by means of a photothermal method. The films were prepared with two basic ingredients, whey protein concentrate and mesquite gum, according to the proportions 75:25, 50:50, 25:75, and 0:100 (weight:weight). The water vapour diffusion coefficient of the analyzed films was found within the interval 0.37 × 10-6 to 2.04 × 10-6 cm^2/s, increasing linearly by increasing the mesquite gum composition in the films. The incorporation of mesquite gum in films produces less effective moisture barriers due to its highly hydrophilic property.

Tomás, S. A.; Saavedra, R.; Cruz, A.; Pedroza-Islas, R.; San Martín, E.

2005-06-01

414

Effects of carbon concentration on microstructure and mechanical properties of as-cast nickel-free Co-28Cr-9W-based dental alloys.  

PubMed

We determined the effects of carbon concentration on the microstructures and tensile properties of the Ni-free Co-29Cr-9W-1Si-C (mass%) cast alloys used in dental applications. Alloy specimens prepared with carbon concentrations in the range 0.01-0.27 mass% were conventionally cast. Scanning electron microscopy (SEM) and electron probe microanalysis (EPMA) revealed that precipitates had formed in all the alloy specimens. The ? phase, a chromium-rich intermetallic compound, had formed in the region between the dendrite arms of the low-carbon-content (e.g., 0.01 C) alloys. Adding carbon to the alloys increased the amount of interdendritic precipitates that formed and changed the precipitation behavior; the precipitated phase changed from the ? phase to the M23C6 carbide with increasing carbon concentration. Adding a small amount of carbon (i.e., 0.04 mass%) to the alloys dramatically enhanced the 0.2% proof stress, which subsequently gradually increased with increasing content of carbon in the alloys. Elongation-to-failure, on the other hand, increased with increasing carbon content and showed a maximum at carbon concentrations of ~0.1 mass%. The M23C6 carbide formed at the interdendritic region may govern the tensile properties of the as-cast Co-Cr-W alloys similar to how it governed those of the hot-rolled alloys prepared in our previous study. PMID:24857474

Yamanaka, Kenta; Mori, Manami; Chiba, Akihiko

2014-07-01

415

Facile nucleation of gold nanoparticles on graphene-based thin films from Au144 molecular precursors  

NASA Astrophysics Data System (ADS)

We demonstrate a facile and cost effective method to obtain gold nanoparticles on graphene by dispersing Au144 molecular nanoclusters by spin coating them in thin layers on graphene-based films and subsequent annealing in a controlled atmosphere. The graphene-based thin films used for these experiments are prepared by solvent-assisted exfoliation of graphite in water in the presence of ribonucleic acid as a surfactant and by subsequent vacuum filtration of the resulting graphene-containing suspensions. Not only is this method easily reproducible, but it leads to gold nanoparticles that are not dependent in size on the number of graphene layers beneath them. This is a distinct advantage over other methods. Plasmonic effects have been detected in our gold nanoparticle-decorated graphene layers, indicating that these thin films may be useful in applications such as plasmonic solar cells and optical memory devices.

Venter, Andrei; Hesari, Mahdi; Shafiq Ahmed, M.; Bauld, Reg; Workentin, Mark S.; Fanchini, Giovanni

2014-04-01

416

Facile nucleation of gold nanoparticles on graphene-based thin films from Au??? molecular precursors.  

PubMed

We demonstrate a facile and cost effective method to obtain gold nanoparticles on graphene by dispersing Au??? molecular nanoclusters by spin coating them in thin layers on graphene-based films and subsequent annealing in a controlled atmosphere. The graphene-based thin films used for these experiments are prepared by solvent-assisted exfoliation of graphite in water in the presence of ribonucleic acid as a surfactant and by subsequent vacuum filtration of the resulting graphene-containing suspensions. Not only is this method easily reproducible, but it leads to gold nanoparticles that are not dependent in size on the number of graphene layers beneath them. This is a distinct advantage over other methods. Plasmonic effects have been detected in our gold nanoparticle-decorated graphene layers, indicating that these thin films may be useful in applications such as plasmonic solar cells and optical memory devices. PMID:24583600

Venter, Andrei; Hesari, Mahdi; Ahmed, M Shafiq; Bauld, Reg; Workentin, Mark S; Fanchini, Giovanni

2014-04-01

417

Enhancing sensing of nitroaromatic vapors by thiophene-based polymer films  

NASA Astrophysics Data System (ADS)

Sensing of nitroaromatic-based explosives is important for homeland security and for the detection of landmines in war zones. These compounds are detected using fluorescence quenching of poly(phenyleneethynylene) (PPE). When compared with PPE, polythiophenes have several features that make them excellent candidates for sensing. However, due to strong ?-? aggregation in polythiophenes, the permeation of the analyte in the thin film is poor. Therefore polythiophenes have poor quenching efficiencies. We have addressed this problem by tuning the side chains on these polymers to disrupt the polymer aggregation, thereby enhancing the analyte diffusion into the polymer thin film. We have now developed a materials platform for next generation sensory materials based on polythiophenes. This talk will discuss our approach and the studies that showed enhanced sensing of nitroaromatics in polythiophene thin films.

Nagarjuna, G.; Kumar, Abhishek; Kokil, Akshay; Jadhav, Kedar; Yurt, Serkan; Kumar, Jayant; Venkataraman, D.

2012-02-01

418

Elaboration of ammonia gas sensors based on electrodeposited polypyrrole--cobalt phthalocyanine hybrid films.  

PubMed

The electrochemical incorporation of a sulfonated cobalt phthalocyanine (sCoPc) in conducting polypyrrole (PPy) was done, in the presence or absence of LiClO4, in order to use the resulting hybrid material for the sensing of ammonia. After electrochemical deposition, the morphological features and structural properties of polypyrrole/phthalocyanine hybrid films were investigated and compared to those of polypyrrole films. A gas sensor consisting in platinum microelectrodes arrays was fabricated using silicon microtechnologies, and the polypyrrole and polypyrrole/phthalocyanine films were electrochemically deposited on the platinum microelectrodes arrays of this gas sensor. When exposed to ammonia, polymer-based gas sensors exhibited a decrease in conductance due to the electron exchange between ammonia and sensitive polymer-based layer. The characteristics of the gas sensors (response time, response amplitude, reversibility) were studied for ammonia concentrations varying from 1 ppm to 100 ppm. Polypyrrole/phthalocyanine films exhibited a high sensitivity and low detection limit to ammonia as well as a fast and reproducible response at room temperature. The response to ammonia exposition of polypyrrole films was found to be strongly enhanced thanks to the incorporation of the phthalocyanine in the polypyrrole matrix. PMID:24209308

Patois, Tilia; Sanchez, Jean-Baptiste; Berger, Franck; Fievet, Patrick; Segut, Olivier; Moutarlier, Virginie; Bouvet, Marcel; Lakard, Boris

2013-12-15

419

An evaluation of the signal and noise characteristics of four CCD-based film digitizers.  

PubMed

Film digitizers are common devices in radiology departments involved with picture archive and communication systems (PACS) and teleradiology. In this paper, we studied the performance of film digitizers based on charge-coupled device detectors (CCD digitizers), and compared this with the performance of a laser digitizer (the de facto standard). Our focus was on the assessment of signal, noise and useful optical density range performance. A function (L* delta D) derived from the Rose model was used to evaluate these parameters in absolute terms, based their predicted ability to detect objects of specific size and optical density difference with respect to background. We studied CCD digitizers from four different vendors and found that none was able to reliably operate up to the maximum density of 3.0 required to digitize plain radiographs, while the laser digitizer was capable of this task. Our analysis also indicated that two of the four CCD digitizers were adequate for digitizing laser-printed cross-sectional images in certain cases. Finally, our analysis indicated that digitization of SMPTE pattern films along with visual assessment of the 5% and 95% contrast patches was not sufficient for determining the utility of film digitizers for clinical tasks. Computation of the L* delta D function provides a useful means of assessing the performance of film digitizers (e.g., for acceptance testing and quality control), and this technique may be adaptable for evaluation of other digital imaging modalities. PMID:9800711

Hangiandreou, N J; O'Connor, T J; Felmlee, J P

1998-10-01

420

Steel casting by diffusion solidification  

Microsoft Academic Search

A new process for casting and welding carbon steels is described in which carbon diffuses isothermally or adiabatically within\\u000a an intimate mixture of solid low carbon steel and high carbon liquid iron to effect solidification and subsequent homogenization\\u000a with respect to carbon. Advantages over conventional casting processes and products result from 1) 150 to 200°C lower casting\\u000a temperature; 2) reduced

George Langford; Robert E. Cunningham

1978-01-01

421

Fiber-Reinforced Slip Castings  

NASA Technical Reports Server (NTRS)

Addition of silica fibers greatly reduces shrinkage and cracking during casting of ceramics. Fiber-reinforced slip-cast silica ceramics are also tougher and have lower dielectric loss. Silica fibers are hyperpure material containing only 1 part per million total metal-ion impurities. Hyperpure fibers ensure high reflectance and allow casting to be fired at temperature greater than 2,200 degrees F without loss of strength from devitrification.

Blome, J. C.; Drennan, D. N.; Keeser, H. M.

1982-01-01

422

Cast dielectric composite linear accelerator  

DOEpatents

A linear accelerator having cast dielectric composite layers integrally formed with conductor electrodes in a solventless fabrication process, with the cast dielectric composite preferably having a nanoparticle filler in an organic polymer such as a thermosetting resin. By incorporating this cast dielectric composite the dielectric constant of critical insulating layers of the transmission lines of the accelerator are increased while simultaneously maintaining high dielectric strengths for the accelerator.

Sanders, David M. (Livermore, CA); Sampayan, Stephen (Manteca, CA); Slenes, Kirk (Albuquerque, NM); Stoller, H. M. (Albuquerque, NM)

2009-11-10

423

High-temperature tribology of silicon nitride lubricated with cesium-based inorganic films  

NASA Astrophysics Data System (ADS)

The high temperature sliding friction and wear of silicon nitride was investigated under unlubricated and solid lubricated conditions. Experiments were performed in laboratory air (18.7% +/- 10.0% R.H.), mostly at 600°C, using a ball-on-disk configuration. Two cesium-based inorganic films were studied; a sodium silicate bonded cesium oxythiotungstate (Cs2WOS 3) coating and a cesium silicate chemical reaction film of the form Cs2O·xSiO2. The selection of these materials was based on previous studies that showed excellent high-temperature performance on sub-scale and full-scale ceramic bearing components. Wear surfaces were characterized by surface profilometry and optical and scanning electron microscopy (SEM). Surface chemistry of selected posttested samples was analyzed using Auger electron spectroscopy (AES) with depth profiling, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Although both of the cesium-based films studied were effective in reducing wear at 600°C, the best tribological performance was obtained with thin chemical reaction films annealed in a sulfur-rich oxidizing environment. Friction coefficients as low as 0.04 and wear factors in the range of 4 x 10 -9 to 1 x 10-8 mm3/N·m were obtained at 600°C with this system. These are comparable to boundary liquid lubricating films at much lower temperatures. The data provide conclusive evidence that neither tungsten nor molybdenum is necessary for low friction at 600°C. The results also suggest that sulfur and cesium play important roles in the formation of a lubricious film. The results show that the lubricating film initially consists of Cs2SO4 deposits that give a mu of 0.10 at 600°C. These deposits subsequently dissolve SiO 2/Si3N4 asperities during sliding via a hot-corrosion mechanism to produce very smooth surfaces. This dissolution process leads to the formation of a lubricious cesium silicate film with mu ˜ 0.04. The tenacity and endurance of the film are thought to be enhanced by the inward diffusion of oxygen and cesium. Diffusion of magnesium out from the silicon nitride substrate (i.e., sintering aid) was also observed and resulted in higher friction.

Rosado, Lewis

2001-11-01

424

Electrodeposited Fe-Ni films prepared from a tartaric-acid-based bath  

NASA Astrophysics Data System (ADS)

Recently, we reported a citric-acid-based plating bath is one of the hopeful plating baths for obtaining Fe-Ni films with good soft magnetic properties. In this report, hydroxylic acid of tartaric acid, which belongs to the same acid group at citric acid, was applied to prepare the films, and the effects of tartaric acid on the magnetic and the structural properties were investigated. Although the overall trend of the effects obtained for tartaric acid resembles our previous results for the citricacid-based bath, the cathode efficiency for the tartaric-acid-based bath shows a slightly higher value as compared with that for the citric-acid-based bath. From these results, we conclude that the tartaric-acid-based bath is also an environmentally friendly plating bath.

Shimokawa, T.; Yanai, T.; Takahashi, K.; Nakano, M.; Fukunaga, H.; Suzuki, K.

2013-06-01

425

Effect of chromium and phosphorus on the physical properties of iron and titanium-based amorphous metallic alloy films  

NASA Technical Reports Server (NTRS)

Amorphous iron and titanium-based alloys containing various amounts of chromium, phosphorus, and boron exhibit high corrosion resistance. Some physical properties of Fe and Ti-based metallic alloy films deposited on a glass substrate by a dc-magnetron sputtering technique are reported. The films were characterized using differential scanning calorimetry, stress analysis, SEM, XRD, SIMS, electron microprobe, and potentiodynamic polarization techniques.

Distefano, S.; Rameshan, R.; Fitzgerald, D. J.

1991-01-01

426

Metal Oxide Nanowire and Thin-Film-Based Gas Sensors for Chemical Warfare Simulants Detection  

Microsoft Academic Search

This work concerns with metal oxide (MOX) gas sensors based on nanowires and thin films. We focus on chemical warfare agents (CWAs) detection to compare these materials from the functional point-of-view. We work with different chemicals including simulants for Sarin nerve agents, vescicant gases, cyanide agents, and analytes such as ethanol, acetone, ammonia, and carbon monoxide that can be produced

Andrea Ponzoni; Camilla Baratto; Sebastiano Bianchi; Elisabetta Comini; Matteo Ferroni; Matteo Pardo; Marco Vezzoli; Alberto Vomiero; Guido Faglia; Giorgio Sberveglieri

2008-01-01

427

Time-dependent all-optical logic gates based on two coupled waves in bacteriorhodopsin film  

Microsoft Academic Search

When two coherent green beams offset from each other by a small angle are coupled in bacteriorhodopsin film, the diffraction intensity rises from zero to a maximum, and then decreases along with the writing time. Based on the change of the diffraction intensity with the writing time, we proposed and demonstrated a time-dependent all-optical exclusive not or (XNOR) operation and

Guiying Chen; Chunping Zhang; Zongxia Guo; Xinyu Wang; Jianguo Tian; Q. W. Song

2005-01-01

428

Digitally tunable optical filter based on DWDM thin film filters and semiconductor optical amplifiers.  

PubMed

We demonstrate a novel digitally tunable optical filter, which is based on dense wavelength division multiplexed (DWDM) thin film filters and semiconductor optical amplifiers (SOA). It has the advantages of fast tuning speed, large tuning range, good temperature stability, simple control mechanism. It is also scalable without bringing additional insertion loss. The passband wavelengths are in consistency with those suggested by ITUT. PMID:19495008

Li, Xinwan; Chen, Jianping; Wu, Guiling; Ye, Ailun

2005-02-21

429

PREDICTING THE BARRIER EFFECTIVENESS OF FLUOROPOLYMER FILM-BASED PROTECTIVE CLOTHING MATERIALS  

EPA Science Inventory

Emergency spill response and hazardous waste cleanup activities often require protective clothing that is an effective barrier to a wide range of chemicals and chemical mixtures. everal clothing products are now available that are based on high barrier films and laminates. xample...

430

Chitosan application for active bio-based films production and potential in the food industry: Review  

Microsoft Academic Search

During the past decade, there was an increasing interest to develop and use bio-based active films which are characterized by antimicrobial and antifungal activities in order to improve food preservation and to reduce the use of chemical preservatives. Biologically active bio-molecules such as chitosan and its derivatives have a significant potential in the food industry in view of contaminations associated

Mohammed Aider

2010-01-01

431

FilmTrust: Movie Recommendations using Trust in Web-based Social Networks  

Microsoft Academic Search

In this paper, we present FilmTrust, a website that integrates Semantic Web-based social networks, augmented with trust, to create predictive movie recommendations. We show how these recommendations are more accurate than other techniques in certain cases, and discuss this technique as a mechanism of Semantic Web interaction.

Jennifer Golbeck; James Hendler

2005-01-01

432

FilmTrust: movie recommendations using trust in web-based social networks  

Microsoft Academic Search

In this paper, we present FilmTrust, a website that integrates Semantic Web-based social networks, augmented with trust, to create predictive movie recommendations. We show how these recommendations are more accurate than other techniques in certain cases, and discuss this technique as a mechanism of Semantic Web interaction.

Jennifer Golbeck; James Hendler

2006-01-01

433