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1

Vacuum casting of thick polymeric films  

NASA Technical Reports Server (NTRS)

Bubble formation and layering, which often plague vacuum-evaporated films, are prevented by properly regulating process parameters. Vacuum casting may be applicable to forming thick films of other polymer/solvent solutions.

Cuddihy, E. F.; Moacanin, J.

1979-01-01

2

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

3

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

4

Double Oxide Film Defects in Cast Magnesium Alloy  

NASA Astrophysics Data System (ADS)

Castings were made in an unfluxed commercial purity Mg alloy in plate molds with both well-designed and poorly designed running system features. The poor running system design was associated with more entrainment of the surface oxide film during mold filling and produced a greater spread in ultimate tensile strength (UTS) and pct elongation values than the castings produced with the good running system design. This is also an effect found in Al alloys where it has also been associated with entrainment of the surface oxide film during mold filling. Scanning electron microscopy of the fracture surfaces of tensile test bars cut from the cast plates revealed oxide film defects comprised of folded over and symmetrical MgO films, similar in form and structure to the double oxide film defects found in Al alloys.

Griffiths, W. D.; Lai, N.-W.

2007-01-01

5

Infiltration of Slag Film into the Grooves on a Continuous Casting Mold  

NASA Astrophysics Data System (ADS)

An analytical model is developed to clarify the slag film infiltration into grooves on a copper mold during the continuous casting of steel slabs. A grooved-type casting mold was applied to investigate the infiltration of slag film into the grooves of a pitch of 0.8 mm, width of 0.7 mm, and depth of 0.6 mm at the vicinity of a meniscus. The plant trial tests were carried out at a casting speed of 5.5 m min-1. The slag film captured at a commercial thin slab casting plant showed that both the overall and the liquid film thickness were decreased exponentially as the distance from the meniscus increases. In contrast, the infiltration of slag film into the grooves had been increased with increasing distance from the meniscus. A theoretic model has been derived based on the measured profile of slag film thickness to calculate the infiltration of slag film into the grooves. It successfully reproduces the empirical observation that infiltration ratio increased sharply along casting direction, about 80 pct at 50 mm and 95 pct at 150 mm below the meniscus. In the model calculation, the infiltration of slag film increases with increasing groove width and/or surface tension of the slag. The effect of groove depth is negligible when the width to depth ratio of the groove is larger than unity. It is expected that the developed model for slag film infiltration in this study will be widely utilized to optimize the design of groove dimensions in continuous casting molds.

Cho, Jung-Wook; Jeong, Hee-Tae

2013-02-01

6

Starch-polyvinyl alcohol cast film-performance and biodegradation  

SciTech Connect

Starch-polyvinyl alcohol (PVOH) cast films were prepared in the absence of plasticizer. Their physical and biodegradable properties were examined. Moisture absorption by the films was similar to that of PVOH at low humidity and increased linearly as the relative humidity increased. The tensile strength of the films decreased with increased humidity and did not display significant improvement with increased PVOH content. Higher PVOH content improved elongation when the relative humidity was 80% or higher. Biodegradation studies revealed that the presence of PVOH in the films slowed the rate of degradation.

Chen, Liang; Imam, S.H.; Stein, T.M. [National Center for Agricultural Utilization Research, Peoria, IL (United States)] [and others

1996-10-01

7

On the membrane approximation in isothermal film casting  

NASA Astrophysics Data System (ADS)

In this work, a one-dimensional model for isothermal film casting is studied. Film casting is an important engineering process to manufacture thin films and sheets from a highly viscous polymer melt. The model equations account for variations in film width and film thickness, and arise from thinness and kinematic assumptions for the free liquid film. The first aspect of our study is a rigorous discussion of the existence and uniqueness of stationary solutions. This objective is approached via the argument principle, exploiting the homotopy invariance of a family of analytic functions. As our second objective, we analyze the linearization of the governing equations about stationary solutions. It is shown that solutions for the associated boundary-initial value problem are given by a strongly continuous semigroup of bounded linear operators. To reach this result, we cast the relevant Cauchy problem in a more accessible form. These transformed equations allow us insight into the regularity of the semigroup, thus yielding the validity of the spectral mapping theorem for the semigroup and the spectrally determined growth property.

Hagen, Thomas

2014-08-01

8

Validation of a model for the cast-film process  

SciTech Connect

We have developed a model of the cast-film process and compared theoretical predictions against experiments on a pilot line. Three polyethylenes with a markedly different level of melt elasticity were used in this evaluation; namely, a high pressure low density polyethylene, LDPE, and two linear low density polyethylenes, LLDPE-1 and LLDPE-2. The final film dimensions of the LDPE were found to be in good agreement with 1-D viscoelastic stationary predictions. Flow field visualization experiments indicate, however, a 2-D velocity field in the airgap between the extrusion die and the chill roll. Taking this observation into account, evolutions of the free surface of the web along the airgap were recorded with LLDPE-2, our least elastic melt. An excellent agreement is found between these measurements and predictions of neck-in and edge bead with 2-D Newtonian stationary simulations. The time-dependent solution, which is based on a linear stability analysis, allows to identify a zone of draw resonance within the working space of the process, defined by the draw ratio, the Deborah number, and the web aspect ratio. It is predicted that increasing this latter parameter stabilizes the process until an optimum value is reached. Experiments with LLDPE-1 are shown to validate this unique theoretical result, thus allowing to increase the draw ratio by about 75%.

Chambon, F. [Exxon Chemical Co., Baytown, TX (United States); Ohlsson, S. [Exxon Chemical Europe, Machelen (Belgium); Silagy, D. [Ecole des Mines de Paris, Sophia-Antipolis (France)

1996-12-31

9

Tape casting and partial melting of Bi-2212 thick films  

NASA Technical Reports Server (NTRS)

To produce Bi-2212 thick films with high critical current densities tape casting and partial melting is a promising fabrication method. Bi-2212 powder and organic additives were mixed into a slurry and tape casted onto glass by the doctor blade tape casting process. The films were cut from the green tape and partially molten on Ag foils during heat treatment. We obtained almost single-phase and well-textured films over the whole thickness of 20 microns. The orientation of the (a,b)-plane of the grains was parallel to the substrate with a misalignment of less than 6 deg. At 77 K/0T a critical current density of 15, 000 A/sq cm was reached in films of the dimension 1 cm x 2 cm x 20 microns (1 micron V/cm criterion, resistively measured). At 4 K/0T the highest value was 350,000 A/sq cm (1 nV/cm criterion, magnetically measured).

Buhl, D.; Lang, TH.; Heeb, B.; Gauckler, L. J.

1995-01-01

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.

11

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

12

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

13

Interfacial thermal conductance in spun-cast polymer films and polymer brushes  

E-print Network

Interfacial thermal conductance in spun-cast polymer films and polymer brushes Mark D. Losego thermal conductivity of amorphous polymers limits significant interfacial effects to polymer film effects in the thermal conductance of spun-cast poly methyl methacrylate PMMA thin films and PMMA brushes

Braun, Paul

14

Alumina casting based on gelation of gelatine  

Microsoft Academic Search

A new colloidal in-situ forming technique based on the gelling property of gelatine is discussed in this paper. A warm slurry containing more than 50vol% alumina powder and a small amount of gelatine (?1wt% of powder weight) is cast into a nonporous mould, and a rigid green body can be produced upon cooling below the so-called gel point of gelatine

Yali Chen; Zhipeng Xie; Jinlong Yang; Yong Huang

1999-01-01

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

Storage stability and antibacterial activity against Escherichia coli O157:H7 of carvacrol in edible apple films made by two different casting methods.  

PubMed

The antimicrobial activities against Escherichia coli O157:H7 as well as the stability of carvacrol, the main constituent of oregano oil, were evaluated during the preparation and storage of apple-based edible films made by two different casting methods, continuous casting and batch casting. Antimicrobial assays of films and high-performance liquid chromatography (HPLC) analysis of film extracts following storage up to 49 days at 5 and 25 degrees C revealed that (a) optimum antimicrobial effects were apparent with carvacrol levels of approximately 1.0% added to the purees prior to film preparation, (b) carvacrol in the films and film weights remained unchanged over the storage period of up to 7 weeks, and (c) casting methods affected carvacrol concentration, bactericidal activity, physicochemical properties, and colors of the apple films. Carvacrol addition to the purees used to prepare the films reduced water vapor and oxygen permeability of apple films. The results indicate that carvacrol has a dual benefit. It can be used to both impart antimicrobial activities and enhance barrier properties of edible films. The cited observations facilitate relating compositional and physicochemical properties of apple puree films containing volatile plant antimicrobials to their use in foods. PMID:18366181

Du, Wen-Xian; Olsen, Carl W; Avena-Bustillos, Roberto J; McHugh, Tara H; Levin, Carol E; Friedman, Mendel

2008-05-14

18

Morphological characterization of ? phase in poly-(vinylidenefluoride) film prepared by spin cast method  

SciTech Connect

Poly-(Vinylidene fluoride) PVDF film was prepared by spin casting method to control the pore size of the matrix. The morphological spherulitic structure was confirmed Scanning Electron Microscopy (SEM) after gold sputtering and the presence of ? phase was ensured in spin cast PVDF film by the FTIR spectroscopy. The ? phase is very important in the application because it improve the properties like piezoelectricity by modifying PVDF crystallinity.

Mehtani, Hitesh Kumar, E-mail: kkraina@gmail.com; Kumar, Rishi, E-mail: kkraina@gmail.com; Raina, K. K., E-mail: kkraina@gmail.com [School of Physics and Materials Science, Thapar University, Patiala-147004 (India)

2014-04-24

19

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

20

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

21

Gelation of a Solution of Poly(3-hexylthiophene) Greatly Retards Its Crystallization Rate in the Subsequently Cast Film.  

PubMed

We compared the crystallization rate of poly(3-hexylthiophene) (P3HT) in the film cast from the gel (called "gel-cast film") with that in the film cast from the liquid solution (called "solution-cast film") to understand the effect of solution structure on the structural development in the subsequently cast film of conjugated polymer. P3HT was found to form a homogeneous liquid solution with xylene at elevated temperature. When the freshly prepared semidilute solution was allowed to age at room temperature, the solution transformed into a gel in which a significant amount of nanowhiskers formed. The nanowhiskers in the gel were effectively transferred to the corresponding cast film, while the film cast from the freshly prepared solution only contained a small amount of such a morphological entity. The in situ small-angle X-ray scattering (SAXS) measurement and thermal analysis revealed that both the cold and melt crystallization of P3HT in the gel-cast film were much slower than those in the solution-cast counterpart. The retardation of crystallization rate in the gel-cast film was attributed to the abundance of the nanowhiskers. In this case, the crystallization of P3HT occurred predominantly within the individual nanowhiskers and the mesh regions in the networks of the whiskers, where their limited sizes in at least one dimension imposed a strong spatial constraint to the crystal growth and chain motion for crystallization. PMID:25406068

Kao, Kuei-Yu; Lo, Shen-Chuan; Chen, Hsin-Lung; Chen, Jean-Hong; Chen, Show-An

2014-12-11

22

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

23

Functional properties of chitosan-based films.  

PubMed

Chitosan-based films plasticized with glycerol were prepared by casting with the aim to obtain environmentally friendly materials for packaging applications. Different contents of glycerol were incorporated into chitosan solutions to improve mechanical properties and all films obtained were flexible and transparent. It was observed that the transparency and good behaviour of the films against UV radiation were not affected by chitosan molecular weight or glycerol content. Moreover, chitosan-based films exhibited excellent barrier properties against water vapour and oxygen, even with the addition of glycerol. The effect of the plasticizer on the properties has been explained using Fourier transform infrared (FTIR) spectroscopic analysis. The changes observed in the intensity of the bands showed that glycerol interacts with chitosan, which could be confirmed by total soluble matter (TSM). PMID:23465939

Leceta, I; Guerrero, P; de la Caba, K

2013-03-01

24

Reversible Tuning of Chemical Structure of Nafion Cast Film by Heat and Acid Treatment.  

PubMed

Effects of annealing have been studied on the chemical structure, water uptake, and acidity of the cast Nafion thin film of thickness ? 6 ?m using a fluorescent probe, 2-(3'-pyridyl)benzimidazole (3PBI), and attenuated total reflactance infrared (ATR-IR) spectroscopy. Nonannealed films and thick Nafion 117 membrane have been used as reference materials, in order to develop a complete understanding of the effect. Annealing has been found to cause a decrease in acidity of otherwise highly acidic ionomer, as sensed by the fluorescent probe and loss of water, as reflected in the ATR-IR spectrum. This observation is surprising and cannot be explained in the light of previous reports of physical changes. Our ATR-IR study has revealed changes in the chemical structure of the hydrophilic part of the ionomer, leading to the formation of sulfonic acid anhydrides. This phenomenon can rationalize the decreased acidity reported in our fluorescence study. Interestingly, acid treatment of the annealed film restores the acidity of the unannealed films. This cannot be rationalized simply by a greater proton uptake from the solution, as the film has to be electroneutral. It appears that the anhydrides formed during the annealing process undergo acid hydrolysis, leading to an increase in the number of SO3(-) groups and, consequently, an increase in the number of H3O(+) ions in the water channels. Besides, the films can be hydrated to an extent that is much greater than Nafion membranes, but the water uptake of acid treated annealed film is slightly less than that of nonannealed films. Hence, we conclude that, along with annealing, acid treatment, a procedure that is generally not performed on the cast films, is an important pretreatment procedure to improve the acidity and hence the transport properties of the cast film. PMID:25275923

Singhal, Nancy; Datta, Anindya

2014-10-21

25

Comparison of directly compressed vitamin B12 tablets prepared from micronized rotary-spun microfibers and cast films.  

PubMed

Abstract Fiber-based dosage forms are potential alternatives of conventional dosage forms from the point of the improved extent and rate of drug dissolution. Rotary-spun polymer fibers and cast films were prepared and micronized in order to direct compress after homogenization with tabletting excipients. Particle size distribution of powder mixtures of micronized fibers and films homogenized with tabletting excipients were determined by laser scattering particle size distribution analyzer. Powder rheological behavior of the mixtures containing micronized fibers and cast films was also compared. Positron annihilation lifetime spectroscopy was applied for the microstructural characterization of micronized fibers and films. The water-soluble vitamin B12 release from the compressed tablets was determined. It was confirmed that the rotary spinning method resulted in homogeneous supramolecularly ordered powder mixture, which was successfully compressed after homogenization with conventional tabletting excipients. The obtained directly compressed tablets showed uniform drug release of low variations. The results highlight the novel application of micronized rotary-spun fibers as intermediate for further processing reserving the original favorable powder characteristics of fibrous systems. PMID:25190153

Sebe, István; Bodai, Zsolt; Eke, Zsuzsanna; Kállai-Szabó, Barnabás; Szabó, Péter; Zelkó, Romána

2014-09-01

26

Nonlinear dynamics and chaotic motion in the isothermal film casting process  

Microsoft Academic Search

In the industrial film casting process with the two-stage cascade (velocity and tension controlled) loop, various aspects\\u000a of nonlinear dynamics and chaotic motion have been investigated solving simple 1-D viscoelastic model. Most of the extensional\\u000a deformation processes exhibit sustained-periodic oscillations or stable limit cycles of state variables (called draw resonance\\u000a instability) beyond the critical onset, even if they are conventionally

Hyun Wook Jung; Joo Sung Lee

2011-01-01

27

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

28

Cast iron-base alloy for cylinder/regenerator housing  

NASA Technical Reports Server (NTRS)

NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

1985-01-01

29

Method of casting pitch based foam  

SciTech Connect

A process for producing molded pitch based foam is disclosed which minimizes cracking. The process includes forming a viscous pitch foam in a container, and then transferring the viscous pitch foam from the container into a mold. The viscous pitch foam in the mold is hardened to provide a carbon foam having a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts.

Klett, James W. (Knoxville, TN)

2002-01-01

30

The metallography of a nickel base casting alloy.  

PubMed

Three groups of tensile test pieces were produced using a nickel base partial denture casting alloy and employing induction fusion in each case. The first group was produced fro new metal, the second from metal which had been recast four times, and the third from new overheated metal. Samples of alloy were cut from each group, and together with a piece from an original ingot, were mounted, polished, etched, and examined under a metallurgical microscope. PMID:1108851

Lewis, A J

1975-10-01

31

Fluid casting of particle-based articles  

DOEpatents

A method 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 or 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.

Menchhofer, Paul (Oak Ridge, TN)

1995-01-01

32

Casting of particle-based hollow shapes  

DOEpatents

A method 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.

Menchhofer, Paul (Oak Ridge, TN)

1995-01-01

33

Casting of particle-based hollow shapes  

DOEpatents

A method 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.

Menchhofer, Paul (Oak Ridge, TN)

1997-01-01

34

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

35

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

36

Preparation and characterization of solution cast films of PET, reorganized PET and their MWNT nanocomposites  

NASA Astrophysics Data System (ADS)

The samples of polyethylene terephthalate (PET), reorganized PET (r-PET) and their nanocomposites with 0.05 wt % and 0.1 wt % multi walled carbon nanotubes (MWNT) were prepared by standard solution casting method using trifluoroacetic acid (TFA) as a solvent. Reorganization of PET was obtained by precipitation method using TFA as a solvent and acetone as an antisolvent. Structural and morphological properties of the films were investigated by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Differential Scanning Calorimetry (DSC) was used to study the thermal properties of the films. Bulk resistivity of the prepared samples was studied using LCR meter. The results show better dispersion of MWNT in r-PET than in PET. Better dispersion is attributed to the morphological changes in r-PET. The films obtained were conductive and transparent even after addition of MWNT signifying their use as a flexible solar substrate.

Singh, Arvind R.; Deshpande, Vineeta D.

2013-06-01

37

Control of mold level in continuous casting based on a disturbance observer  

Microsoft Academic Search

Regulating molten steel level in continuous casting is difficult because it suffers from various disturbances, among which the bulging disturbance is the most prominent. Moreover, as the casting speed increases in continuous casting, the phase lag due to the system delay increases. To eliminate the bulging disturbance in the presence of system delay, we propose an adaptive sine estimator based

Minsung Kim; SungWoong Moon; Changheum Na; Dukman Lee; Yeongsub Kueon; Jin S. Lee

2011-01-01

38

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

39

FLATNESS BASED OPEN LOOP CONTROL FOR THE TWIN ROLL STRIP CASTING  

E-print Network

method of continuous casting involves pouring the liquid steel directly into the gap of two horizontalFLATNESS BASED OPEN LOOP CONTROL FOR THE TWIN ROLL STRIP CASTING PROCESS Ch. Fleck ,1 Th. Paulus ,2, D-52074 Aachen, Germany Abstract: Strip casting technology is the most recent innovative steel

Ollivier, François

40

FLATNESS BASED OPEN LOOP CONTROL FOR THE TWIN ROLL STRIP CASTING  

E-print Network

method of continuous casting involves pouring the liquid steel directly into the gap of two horizontalFLATNESS BASED OPEN LOOP CONTROL FOR THE TWIN ROLL STRIP CASTING PROCESS Ch. Fleck #,1 Th. Paulus, Steinbachstr. 54, D­52074 Aachen, Germany Abstract: Strip casting technology is the most recent innovative

Ollivier, François

41

Evaporation-induced ordering in solution-cast block copolymer thin films  

NASA Astrophysics Data System (ADS)

Block copolymer thin films are currently being investigated for a wide variety of applications, ranging from separation membranes to organic photovoltaics and lithographic masks. Over the last decade or so, there has been mounting interest in using solvent casting techniques to control morphology selection in thin films either through spin coating, drop casting, or simple annealing under a mixture of solvent vapors. While these added degrees of freedom and process variables offer the promise of enhanced morphology control, they necessarily add extra dimensions and inter-dependencies between parameters that must be sorted out before this control can be effectively exercised. To this end, we have adapted a dynamical extension of Self-Consistent Field Theory to study the dynamics of ordering from a dilute copolymer solution to a dry, ordered thin film. This talk will offer a visual summary of the range in behavior available to a single copolymer + neutral solvent system in both 2D (lamella-forming) and 3D (cylinder-forming) environments. In addition, a brief analysis will be presented on the competing time scales, equilibrium, and non-equilibrium effects that appear to govern the initiation event and propagation of evaporation-induced ordering fronts.

Paradiso, Sean; Delaney, Kris; Ceniceros, Hector; Garcia-Cervera, Carlos; Fredrickson, Glenn

2013-03-01

42

Investigation of Polymer Film Spin Casting: Solvent Properties that Create Optimal Film Quality and Use of Selective Solvents for Multilayered Films  

NASA Astrophysics Data System (ADS)

Spin casting of polymer films is extremely important for many applications, including the field of polymers at interfaces or in confined geometries. Creating smooth, uniform films is paramount for proper experimental characterization, yet there is little fundamental understanding of the parameters involved in creating such films. We have attempted to take a systematic approach in determining optimal solution conditions, with particular attention to solvent parameters, that provide films with minimal artifacts and conditions that allow spinning of one polymer directly onto another with sharp, even interfaces. Several systems have been characterized with optical microscopy and atomic force microscopy (AFM), and results show a strong correlation between solvent vapor pressure and film morphology. A new solvent, 1-chloropentane, is introduced for selective spinning of PS on PMMA or P2VP. The phase behavior of PS/1-chloropentane and PMMA/1-chloropentane has been characterized with inverse gas chromatography (IGC) and static light scattering (SLS).

Ennis, Dave; Harton, Shane; Kloxin, Christopher; Betz, Heike; Danner, Ronald; Spontak, Richard; Ade, Harald

2004-03-01

43

Optimization of a 0.69PZT-0.31PZNN thick film by controlling slurry viscosity and tape-casting blade height  

NASA Astrophysics Data System (ADS)

We investigated how the viscosities of piezoelectric lead zirconate titanate/lead zirconate nickel niobate (PZT-PZNN) slurry samples affect the laminated-film densities based on various conditions of degassing time for 0, 30, and 60 min. PZT-PZNN slurries with different viscosities were tape casted into green sheets by adjusting the comma blade height to 100, 200, 300, 400, and 500 ?m. As a result the slurry viscosity linearly increased with increasing slurry degassing time, and the thickness of the green sheet increased with increasing comma blade height. The density and the dielectric properties of piezoelectric ceramic films with the same thicknesses, but composed of different numbers of layers, were compared. The laminated-film density and the dielectric property d33 × g33 increased with decreasing number of laminated layers. However, when the viscosity of the slurry was too high (degassing time > 60 min) and the comma blade height was too high (comma blade height > 300 ?m), the tape-casted green sheet was too thick to have enough time to dry. By controlling the slurry viscosity by adjusting the degassing time and the comma blade height, we were able to optimize the thickness of the green sheet in a tape-casting. The optimal green sheet thickness was < 70 ?m, and the number of sheets laminated should be minimized to increase the film's density and dielectric constant.

Song, Daniel; Woo, Min Sik; Ahn, Jung Hwan; Sung, Tae Hyun; Kim, Kyoung Bum

2014-12-01

44

Surface properties and biocompatibility of solvent-cast poly[-caprolactone] films.  

PubMed

Poly(epsilon-caprolactone) (PCL) was dissolved in four solvent systems, chloroform, tetrahydrofuran, acetone and ethyl acetate, and cast onto glass Petri dishes. The surface properties of the resulting films were investigated. The extent to which their properties were determined by the solvent used in each case was quantified in terms of contact angle, surface morphology, attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and the adhesion and proliferation of fibroblasts by direct contact. The surface of the PCL film in contact with glass was denoted the SG surface, and the other, which was exposed to the gas phase, a mixture of air and residual solvent vapour, was denoted the SA surface. In the case of hydrophobic solvent systems, the advancing contact angle of the SG surface was always lower than that of the SA surface. With hydrophilic solvent systems, on the other hand, the advancing contact angle of the SG film surface was higher when the contact angle of the Petri dish was higher than that of the gaseous mixture of the air and solvent vapour, otherwise it was lower or equal to that of the surface on which it was cast. The surface morphology was dictated by the solubility of PCL in the respective solvent systems: high dissolution solvents such as chloroform and tetrahydrofuran produced films that comprised PCL aggregates, the particles being larger in the case of chloroform, whereas the less efficient solvents (acetone and ethyl acetate) resulted in a filamentous structure. The ATR-FTIR results confirmed that the chemistry of the SA surfaces differed according to the solvent system used. Preliminary cell culture experiments carried out with the PCL films established that murine (L929) fibroblasts grew well on all surfaces regardless of the solvent used, although the rates of adhesion and proliferation were not as great as on tissue culture plastic controls. Of all the surfaces examined in this study, the cells favoured the SG aspect of ethyl acetate cast PCL films, the surface of which had the finest pore size and relatively low contact angle. PMID:15120520

Tang, Z G; Black, R A; Curran, J M; Hunt, J A; Rhodes, N P; Williams, D F

2004-08-01

45

In situ observation of cluster formation during nanoparticle solution casting on a colloidal film.  

PubMed

We present a real-time study of the nanostructuring and cluster formation of gold nanoparticles deposited in aqueous solution on top of a pre-structured polystyrene colloidal thin film. Cluster formation takes place at different length scales, from the agglomerations of the gold nanoparticles to domains of polystyrene colloids. By combining in situ imaging ellipsometry and microbeam grazing incidence small-angle x-ray scattering, we are able to identify different stages of nanocomposite formation, namely diffusion, roughness increase, layer build-up and compaction. The findings can serve as a guideline for nanocomposite tailoring by solution casting. PMID:21654049

Roth, S V; Herzog, G; Körstgens, V; Buffet, A; Schwartzkopf, M; Perlich, J; Abul Kashem, M M; Döhrmann, R; Gehrke, R; Rothkirch, A; Stassig, K; Wurth, W; Benecke, G; Li, C; Fratzl, P; Rawolle, M; Müller-Buschbaum, P

2011-06-29

46

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

47

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

48

Organic field-effect transistors with solution-processible thiophene/phenylene based-oligomer derivative films  

NASA Astrophysics Data System (ADS)

Solution-processible thiophene/phenylene -based oligomer derivatives with different end substituents are presented as p-type semiconducting materials in OFETs. These films were deposited on OTS-treated SiO II/Si or polymeric bivinyltetramethyldisiloxane-bis(benzocyclobutene) (BCB)/ITO/quartz substrates, via drop-casting and spin-casting. Synchrotron-based grazing-incidence X-ray diffraction and atomic force microscopy reveals that both drop- and spin-cast films have highly crystalline structures with edge-on molecules and parallel ?-? stacking conjugated planes with respect to the substrate. In particular, temperature-dependent solubility of these materials can give a strategy for highly ordered crystalline structure in spin-cast films grown on cooler substrates, when compared to warmed solutions. Field-effect mobilities of these spin-cast films in a top-contacted electrode OFETs with BCB dielectrics are reached as high as ~0.01 cm2/Vs.

Yang, Hoichang; Locklin, Jason; Singh, Birendra; Bao, Zhenan

2007-09-01

49

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

NASA Astrophysics Data System (ADS)

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 essential. Various ion-exchange polymer films with thickness of 0.4-1.2 mm have been prepared by casting of liquid ion-exchange polymer. As well, IPMC actuators using cast ion-exchange polymer films have been fabricated and the basic mechanical characteristics such as stiffness, displacement and force were measured and analyzed. These results can be used for the optimized design of actuators for different applications.

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

2003-07-01

50

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

51

Sensor-based assessment of cast placement and removal.  

PubMed

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

52

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

53

A scanning Kelvin probe study of charge trapping in zone-cast pentacene thin film transistors  

NASA Astrophysics Data System (ADS)

We have used scanning Kelvin probe microscopy (SKPM) as a local probe to study charge trapping in zone-cast pentacene field effect transistors on both SiO2 and benzocyclobutene (BCB) substrates. Annealing at 130 °C was found to reduce the threshold voltage, susceptibility to negative gate bias stress and trapping of positive charges within single pentacene grains. We conclude that oxygen is able to penetrate and disassociatively incorporate into crystalline pentacene, chemically creating electrically active defect states. Screening of a positive gate bias caused by electron injection from Au into pentacene was directly observed with SKPM. The rate of screening was found to change significantly after annealing of the film and depended on the choice of gate dielectric.

Hallam, T.; Duffy, C. M.; Minakata, T.; Ando, M.; Sirringhaus, H.

2009-01-01

54

Effectiveness of silane monomer and gamma radiation on chitosan films and PCL-based composites  

NASA Astrophysics Data System (ADS)

Chitosan films were prepared by casting from its 1% (w/w) solution. Tensile strength (TS) and tensile modulus (TM) of chitosan films were found to be 30 MPa and 450 MPa, respectively. Silane monomer (3-aminopropyl tri-methoxysilane) (0.25%, w/w) was added into the chitosan solution (1%, w/w) and films were casted. Then films were exposed to gamma radiation (5-25 kGy) and mechanical properties were investigated. It was found that at 10 kGy, the values of TS and TM were improved significantly. Silane grafted chitosan film reinforced poly(caprolactone) (PCL)-based tri-layer composites were prepared by compression molding. Silane improved interfacial adhesion between chitosan and PCL in composites. Surface of the films was investigated by scanning electron microscope (SEM) and found better morphology for silane grafted films.

Sharmin, Nusrat; Khan, Ruhul A.; Dussault, Dominic; Salmieri, Stephane; Akter, Nousin; Lacroix, Monique

2012-08-01

55

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

NASA Astrophysics Data System (ADS)

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.

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

2012-02-01

56

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

57

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 Abstract: There is a growing interest in the use of fabrics as reinforcements for cement composites due processing methods, casting and pultrusion, on the tensile properties of fabric-cement composites. Four

Mobasher, Barzin

58

The metallography of heat treatment effects in a nickel-base casting alloy. A preliminary report.  

PubMed

A series of standard tensile specimens produced from a nickel-base removable partial denture casting alloy were subjected to heat treatments at three temperatures and three periods at each temperature. The microstructures developed within the castings disclose changes in both the matrix and interdendritic zones. PMID:296698

Goodall, T G; Lewis, A J

1979-08-01

59

High solids loading for water-based tape casting  

NASA Astrophysics Data System (ADS)

Tape Casting is a low cost process for making large-area, thin, flat ceramics, which traditionally utilizes organic solvents to allow fast drying.sp{1-4} However, some of the volatile organic compounds (VOC), such as toluene, methylethyl ketone (MEK), and cyclohexanone, are hazardous air pollutants, and their emissions need to be regulated. Therefore, using water as a solvent is desirable to avoid the need of trapping VOCs. Although water is of low cost, nonflammable and safe to the environment, its heat of vaporization is high, 540 kca/g, compared to that of toluene, 74 kca/g.sp7 This makes the drying slow when water is used. The use of water in a tape casting formulation has previously been practical just for applications which require very thin tape, 100-200 mum. A high solids loading of above 50 vol% is an alternative approach to obtain sufficiently rapid drying for a thicker tape (up to 0.8 mm) since the water content is originally minimized. In order to obtain a high solids loading, the dispersants and binder systems were carefully tailored during the present research project. Low molecular weight polyelectrolytes, such as polyacrylic acid PAA (M.W. 1800) and citric acid, were found to be effective for high solids loading of Alsb2Osb3 (A-16SG), for which the electrosteric stabilization played an important role to the stability of the suspension. The viscosity and flow behavior of the suspension strongly depended on pH and the amount of polyelectrolyte, which could be related to the configuration of the polyelectrolyte molecules on the powder surface. The high solids loading of 64.5 vol% could be obtained for the fine A-16SG powder which had a surface area of 9.3 msp2/g. For the coarser powder, A-152SG, the dilatancy was a major problem that obstructed a further rise in solids loading. The dilatancy could be minimized by modifying the size distribution with A-152SG plus A-16SG and using a proper pH and amount of dispersants. An extremely high solids loading of 71-73 vol% could be reached in an aqueous system for the size-modified powder, before binder addition. An emulsion binder (Duramaxsp{TM} B-1001) aided the reduction in viscosity of the high solids loading suspension, while the soluble binder aggravated the agglomeration and drastically raised the viscosity. The emulsion binder used also had high polymer content and, therefore, less water. The final solids loadings obtained were 55.7 vol% for A-16SG and 63 vol% for mixed A-152SG and A-16SG powder. The drying time was reduced by one third for the 63 vol% formulation compared to the 55.7 vol% formulation. Water-based tape casting of A1N was possible in a buffer solution. Polyacrylic acid, PAA (M.W. 1800), aided dispersion and also minimized hydrolysis of A1N in water. Poly(vinyl pyrrolidone), PVP (M.W. 160,000), gave a lower viscosity to suspension compared to poly(vinyl alcohol) and cellulose ether, and had less bubble formation. The suspension could be processed for more than 72 h without degradation. With optimization of dispersant and binder, a high solids loading formulation of 52 vol% could be obtained. When the organic components were burned out in the air, AlN with 3wt% Ysb2Osb3 could be sintered at 1800sp°C for 1 h without degradation. The thermal conductivity was up to 153 W/m.K.

Suwannasiri, Thitima

60

Nanocrystalline cellulose (NCC) reinforced alginate based biodegradable nanocomposite film.  

PubMed

Nanocrystalline cellulose (NCC) reinforced alginate-based nanocomposite film was prepared by solution casting. The NCC content in the matrix was varied from 1 to 8% ((w/w) % dry matrix). It was found that the nanocomposite reinforced with 5 wt% NCC content exhibits the highest tensile strength which was increased by 37% compared to the control. Incorporation of NCC also significantly improved water vapor permeability (WVP) of the nanocomposite showing a 31% decrease due to 5 wt% NCC loading. Molecular interactions between alginate and NCC were supported by Fourier Transform Infrared Spectroscopy. The X-ray diffraction studies also confirmed the appearance of crystalline peaks due to the presence of NCC inside the films. Thermal stability of alginate-based nanocomposite films was improved after incorporation of NCC. PMID:22944444

Huq, Tanzina; Salmieri, Stephane; Khan, Avik; Khan, Ruhul A; Le Tien, Canh; Riedl, Bernard; Fraschini, Carole; Bouchard, Jean; Uribe-Calderon, Jorge; Kamal, Musa R; Lacroix, Monique

2012-11-01

61

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

62

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

63

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

64

A Medial Point Cloud based Algorithm for Dental Cast Segmentation  

E-print Network

as dental cast scans) for the application in consumer oral healthcare devices. Although these can shape analysis requirements. I. INTRODUCTION Oral Healthcare devices targeted at the consumer market re the shape properties of a personal oral healthcare device, one has to use simpler, however less detailed

Telea, Alexandru C.

65

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

66

Mechanical and barrier properties of nanocrystalline cellulose reinforced chitosan based nanocomposite films.  

PubMed

Nanocrystalline cellulose (NCC) reinforced chitosan-based biodegradable films were prepared by solution casting. The NCC content in the films was varied from 1 to 10% (dry wt. basis). It was found that the tensile strength (TS) of the nanocomposite films with 5% (w/w) NCC content was optimum with an improvement of 26% compared to the control chitosan films. Incorporation of NCC also significantly improved barrier properties. Water vapor permeability (WVP) of the chitosan/NCC films was decreased by 27% for the optimum 5% (w/w) NCC content. Swelling studies revealed a decrease in water uptake of the NCC-reinforced chitosan films. Analyses of thermal properties showed no significant effect of NCC whereas X-ray diffraction studies confirmed the appearance of crystalline peaks in the nanocomposite films. Surface morphology of the films was investigated by scanning electron microscopy and it was found that NCC was dispersed homogenously into chitosan matrix. PMID:22944422

Khan, Avik; Khan, Ruhul A; Salmieri, Stephane; Le Tien, Canh; Riedl, Bernard; Bouchard, Jean; Chauve, Gregory; Tan, Victor; Kamal, Musa R; Lacroix, Monique

2012-11-01

67

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

68

Cast Away  

Microsoft Academic Search

To strand actor Tom hanks on a deserted island, Cast Away begins with a visceral plane crash sequence incorporating CG water & waves, live action & miniature photography and numerous subtle digital effects. Once on the island, Hanks surveys the landscape revealing his isolation. Combining live action photography filmed in a parking lot in Malibu with a completely CG created

2001-01-01

69

Antimicrobial and physical-mechanical properties of agar-based films incorporated with grapefruit seed extract.  

PubMed

The use of synthetic petroleum based packaging films caused serious environmental problems due to their difficulty in recycling and poor biodegradability. Therefore, present study was aimed to develop natural biopolymer-based antimicrobial packaging films as an alternative for the synthetic packaging films. As a natural antimicrobial agent, grapefruit seed extract (GSE) has been incorporated into agar to prepare antimicrobial packaging film. The films with different concentrations of GSE were prepared by a solvent casting method and the resulting composite films were examined physically and mechanically. In addition, the films were characterized by FE-SEM, XRD, FT-IR and TGA. The incorporation of GSE caused increase in color, UV barrier, moisture content, water solubility and water vapor permeability, while decrease in surface hydrophobicity, tensile strength and elastic modulus of the films. As the concentration of GSE increased from 0.6 to 13.3 ?g/mL, the physical and mechanical properties of the films were affected significantly. The addition of GSE changed film microstructure of the film, but did not influence the crystallinity of agar and thermal stability of the agar-based films. The agar/GSE films exhibited distinctive antimicrobial activity against three test food pathogens, such as Listeria monocytogenes, Bacillus cereus and Escherichia coli. These results suggest that agar/GSE films have potential to be used in an active food packaging systems for maintaining food safety and extending the shelf-life of the packaged food. PMID:24507339

Kanmani, Paulraj; Rhim, Jong-Whan

2014-02-15

70

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

71

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 ...

72

Facile preparation and thermoelectric properties of Bi?Te? based alloy nanosheet/PEDOT:PSS composite films.  

PubMed

Bi2Te3 based alloy nanosheet (NS)/poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) composite films were prepared separately by spin coating and drop casting techniques. The drop cast composite film containing 4.10 wt % Bi2Te3 based alloy NSs showed electrical conductivity as high as 1295.21 S/cm, which is higher than that (753.8 S/cm) of a dimethyl sulfoxide doped PEDOT:PSS film prepared under the same condition and that (850-1250 S/cm) of the Bi2Te3 based alloy bulk material. The composite film also showed a very high power factor value, ?32.26 ?Wm(-1) K(-2). With the content of Bi2Te3 based alloy NSs increasing from 0 to 4.10 wt %, the electrical conductivity and Seebeck coefficient of the composite films increase simultaneously. PMID:24666341

Du, Yong; Cai, K F; Chen, Song; Cizek, Pavel; Lin, Tong

2014-04-23

73

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

74

High-Throughput Physiologically Based Toxicokinetic Models for ToxCast Chemicals  

EPA Science Inventory

Physiologically based toxicokinetic (PBTK) models aid in predicting exposure doses needed to create tissue concentrations equivalent to those identified as bioactive by ToxCast. We have implemented four empirical and physiologically-based toxicokinetic (TK) models within a new R ...

75

Effect of casting geometry on mechanical properties of two nickel-base superalloys  

NASA Technical Reports Server (NTRS)

An investigation was performed to determine mechanical properties of two rhenium-free modifications of alloy TRW, and to evaluate the suitability of the alloy for use in a small integrally cast turbine rotor. The two alloys were initially developed using stress rupture properties of specimens machined from solid gas turbine blades. Properties in this investigation were determined from cast to size bars and bars cut from 3.8 by 7.6 by 17.8 cm blocks. Specimens machined from blocks had inferior tensile strength and always had markedly poorer rupture lives than cast to size bars. At 1,000 C the cast to size bars had shorter rupture lives than those machined from blades. Alloy R generally had better properties than alloy S in the conditions evaluated. The results show the importance of casting geometry on mechanical properties of nickel base superalloys and suggest that the geometry of a component can be simulated when developing alloys for that component.

Johnston, J. R.; Dreshfield, R. L.; Collins, H. E.

1976-01-01

76

Welding and mechanical properties of cast FAPY (Fe-16 at. % Al-based) alloy slabs  

SciTech Connect

The low-aluminum-content iron-aluminum program deals with the development of a Fe-Al alloy with aluminum content such as a produce the minimum environmental effect at room temperature. The FAPY is an Fe-16 at. % Al-based alloy developed at the Oak Ridge National Laboratory as the highest aluminum-containing alloy with essentially no environmental effect. The chemical composition for FAPY in weight percent is: aluminum = 8.46, chromium = 5.50, zirconium = 0.20, carbon = 0.03, molybdenum = 2.00, yttrium = 0.10, and iron = 83.71. The cast ingots of the alloy can be hot worked by extrusion, forging, and rolling processes. The hot- worked cast structure can be cold worked with intermediate anneals at 800{degrees}C. Typical room-temperature ductility of the fine-grained wrought structure is 20 to 25% for this alloy. In contrast to the wrought structure, the cast ductility at room temperature is approximately 1% with a transition temperature of approximately 100 to 150{degrees}C, above which ductility values exceed 20%. The alloy has been melted and processed into bar, sheet, and foil. The alloy has also been cast into slabs, step-blocks of varying thicknesses, and shapes. The purpose of this section is to describe the welding response of cast slabs of three different thicknesses of FAPY alloy. Tensile, creep, and Charpy-impact data of the welded plates are also presented.

Sikka, V.K.; Goodwin, G.M.; Alexander, D.J.; Howell, C.R.

1995-08-01

77

Efficacy of powder-based three-dimensional printing (3DP) technologies for rapid casting of light alloys  

Microsoft Academic Search

The aim of the present research was to compare the efficacy of two powder based 3D printing technologies for rapid casting\\u000a of light alloys. The technologies of ZCast process and investment casting were employed to cast aluminium A356 alloy and zinc\\u000a ZA-12 alloy. The split pattern shells were printed in ZCast501 powder and used directly as mould with outside sand

Simranpreet Singh Gill; Munish Kaplas

2011-01-01

78

AN IMPLICIT CONTROLLER FOR THE STEEL LEVEL REGULATION IN A VACUUM-BASED CONTINUOUS CASTING PROCESS  

Microsoft Academic Search

A nonlinear mathematical model of a vacuum-based continuous casting process and an implicit nonlinear controller are developed. The aim of the controller is the regulation of the mold and tundish molten steel levels. In the proposed approach, the output error is designed to be asymptotically stable, and the current values of the control inputs are numerically determined using the Newton-Rapson

M. A. Barrón; J. González

2003-01-01

79

The effect of aluminium on the metallography of a nickel base removable partial denture casting alloy.  

PubMed

Three special nickel-chromium alloys were prepared in which the aluminum levels were adjusted both above and below that of a commercial nickel base dental casting alloy. Tensile and metallographic evaluation of representative samples of the alloys were made and the changes in the properties of the alloys are reported. PMID:285671

Lewis, A J

1978-12-01

80

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

81

Computation of Thermal Behavior During Solidification of Aluminium Base Alloys Castings Cast in CO2-Sand Mold  

NASA Astrophysics Data System (ADS)

Solidification of molten metals during various casting methods poses many practical problems associated with phase transformation and heat transfer processes. Evaluation of solidification time is one of the very important parameters used for assessing the properties of the material. In the present study, experimental investigation is carried out to measure the solidification time in a cylindrical hollow casting cast in CO2-Sand molds and the same has been compared with the results obtained through computed by using an implicit alternating direction (IAD) method, including the treatment of interfacial nodes between metal and mold, and boundary nodes at the mold surface. Aluminum-4.5% copper alloy has been used. Computed cooling curves at various locations and temperature distributions in casting-metal-mold are presented. The results shows that the solidification time obtained by experimental study compares well with the one predicted by the analysis made through IAD modeling. A successful comparison with reported experimental results shows that the technique is appropriate for simulation of solidification process of aluminium castings.

Kulkarni, S. N.; Radhakrishna, K.

82

Mathematical modeling and optimization strategies (genetic algorithm and knowledge base) applied to the continuous casting of steel  

Microsoft Academic Search

The control of quality in continuous casting products cannot be achieved without a knowledge base which incorporates parameters and variables of influence such as: equipment characteristics, steel, each component of the system and operational conditions. This work presents the development of a computational algorithm (software) applied to maximize the quality of steel billets produced by continuous casting. A mathematical model

C. A. Santos; J. A. Spim; A. Garcia

2003-01-01

83

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

84

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

85

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

86

Patellar dislocation: cylinder cast, splint or brace? An evidence-based review of the literature  

PubMed Central

Patellar dislocations are a common injury in the emergency department. The conservative management consists of immobilisation with a cylinder cast, posterior splint or removable knee brace. No consensus seems to exist on the most appropriate means of conservative treatment or the duration of immobilisation. Therefore the aims of this review were first to examine whether immobilisation with a cylinder cast causes less redislocation and joint movement restriction than a knee brace or posterior splint and second to compare the redislocation rates after conservative treatment with surgical treatment. A systematic search of Pubmed, Embase and the Cochrane Library was performed. We identified 470 articles. After applying the exclusion and inclusion criteria, only one relevant study comparing conservative treatment with a cylinder cast, brace and posterior splint remained (Mäenpää et al.). In this study, the redislocation frequency per follow-up year was significant higher in the brace group (0.29; p?cast group (0.12) and the posterior splint group (0.08). The proportion of loss of flexion and extension was the highest in the cylinder cast group and the lowest in the posterior splint group (not significant). The evidence level remained low because of the small study population, difference in duration of immobilisation between groups and use of old braces. Also, 12 studies comparing surgical with conservative treatment were assessed. Only one study reported significantly different redislocation rates after surgical treatment. In conclusion, a posterior splint might be the best therapeutic option because of the low redislocation rates and knee joint restrictions. However, this recommendation is based on only one study with significant limitations. Further investigation with modern braces and standardisation of immobilisation time is needed to find the most appropriate conservative treatment for patellar luxation. Furthermore, there is insufficient evidence to confirm the added value of surgical management. PMID:23273401

2012-01-01

87

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

88

Preparation and properties of films cast from mixtures of poly(vinyl alcohol) and submicron particles prepared from amylose-palmitic acid inclusion complexes.  

PubMed

The use of starch in polymer composites for film production has been studied for increasing biodegradability, improving film properties and reducing cost. In this study, submicron particles were prepared from amylose-sodium palmitate complexes both by rapidly cooling jet-cooked starch-palmitic acid mixtures and by acidifying solutions of starch-sodium palmitate complexes. Films were cast containing poly(vinyl alcohol) (PVOH) with up to 50% starch particles. Tensile strength decreased and Young's modulus increased with starch concentration, but percent elongations remained similar to controls regardless of preparation method or starch content. Microscopy showed particulate starch distribution in films made with rapidly cooled starch-palmitic acid particles but smooth, diffuse starch staining with acidified sodium palmitate complexes. The mild effects on tensile properties suggest that submicron starch particles prepared from amylose-palmitic acid complexes provide a useful, commercially viable approach for PVOH film modification. PMID:25659717

Fanta, George F; Selling, Gordon W; Felker, Frederick C; Kenar, James A

2015-05-01

89

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

90

Resistance thermometers based on the germanium films  

Microsoft Academic Search

The latest achievements in the field of development of resistance thermometers based on the germanium films on gallium arsenide are presented and summarized. Basic models of Ge film thermometers, which cover the temperature range from 0.02 to 500 K, are considered. Character- istics of the thermometers in high magnetic fields and under the action of ionizing irradiation (neutrons and gamma-rays)

V. F. Mitin

91

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

92

-Based Mold Flux Used for High Al-TRIP Steel Casting  

NASA Astrophysics Data System (ADS)

An investigation was carried out to study the effect of MnO on crystallization, melting, and heat transfer of lime-alumina-based mold flux used for high Al-TRIP steel casting, through applying the infrared emitter technique (IET) and the double hot thermocouple technique (DHTT). The results of IET tests showed that MnO could improve the general heat transfer rate through promoting the melting and inhibiting the crystallization of mold flux; meanwhile the radiative heat flux was being attenuated. DHTT experiments indicated that the crystallization fraction, melting temperature of mold flux decreased with the addition of MnO. The results of this study can further elucidate the properties of the CaO-Al2O3 slag system and reinforce the basis for the application of lime-alumina system mold fluxes for casting high Al steels.

Zhao, Huan; Wang, Wanlin; Zhou, Lejun; Lu, Boxun; Kang, Youn-Bae

2014-08-01

93

Fracture process in tensile testing dental Ni-base casting alloys.  

PubMed

Early-fracture in tensile specimens was found in Ni-base casting alloys which were obtained in conventional casting condition. In 32 Ni-23 Cu-25 Mn alloy, intercrystalline fracture occurred in both early-fractured and normal ductile specimens. On the contrary, intercrystalline and innercrystalline fracture were, respectively, found in early-fractured and normal samples. As the fracture process, voids formed by stress-concentration around A-grain and brittle fracture of soft B-grain in 32 Ni-23 Cu-25 Mn alloy, while voids occurred by stress-concentration around inclusion as chromium carbide and slip deformation on the maximum shear stress plane in 84 Ni-9 Cr alloy. PMID:6949997

Wakasa, K; Yamaki, M; Nakatuka, A; Nishimura, T

1981-10-01

94

Spin-cast P(VDF-TrFE) films for high performance medical ultrasound transducers  

Microsoft Academic Search

Ferroelectric polymers are used in many special medical and industrial ultrasonic transducer applications. In most of these applications a free-standing metallized (i.e., patterned) film is adhered to a substrate material which is either reflective (i.e., high acoustic impedance) or acoustically matched in impedance but highly lossy. The adhesive layer can have adverse effects on ultrasonic transducer performance, especially at high

L. F. Brown; R. L. Carlson; J. M. Sempsrott

1997-01-01

95

Investigation into stability of poly(vinyl alcohol)-based Opadry® II films.  

PubMed

Poly(vinyl alcohol) (PVA)-based formulations are used for pharmaceutical tablet coating with numerous advantages. Our objective is to study the stability of PVA-based coating films in the presence of acidic additives, alkaline additives, and various common impurities typically found in tablet formulations. Opadry® II 85F was used as the model PVA-based coating formulation. The additives and impurities were incorporated into the polymer suspension prior to film casting. Control and test films were analyzed before and after exposure to 40°C/75% relative humidity. Tests included film disintegration, size-exclusion chromatography, thermal analysis, and microscopy. Under stressed conditions, acidic additives (hydrochloric acid (HCl) and ammonium bisulfate (NH(4)HSO(4))) negatively impacted Opadry® II 85F film disintegration while NaOH, formaldehyde, and peroxide did not. Absence of PVA species from the disintegration media corresponded to an increase in crystallinity of PVA for reacted films containing HCl. Films with NH(4)HSO(4) exhibited slower rate of reactivity and less elevation in melting temperature with no clear change in melting enthalpy. Acidic additives posed greater risk of compromise in disintegration of PVA-based coatings than alkaline or common impurities. The mechanism of acid-induced reactivity due to the presence of acidic salts (HCl vs. NH(4)HSO(4)) may be different. PMID:21647800

Koo, Otilia M Y; Fiske, John D; Yang, Haitao; Nikfar, Faranak; Thakur, Ajit; Scheer, Barry; Adams, Monica L

2011-06-01

96

Preparation and characterization of chitosan-based nanocomposite films with antimicrobial activity.  

PubMed

Four different types of chitosan-based nanocomposite films were prepared using a solvent-casting method by incorporation with four types of nanoparticles, that is, an unmodified montmorillonite (Na-MMT), an organically modified montmorillonite (Cloisite 30B), a Nano-silver, and a Ag-zeolite (Ag-Ion). X-ray diffraction patterns of the nanocomposite films indicated that a certain degree of intercalation was formed in the nanocomposite films, with the highest intercalation in the Na-MMT-incorporated films followed by films with Cloisite 30B and Ag-Ion. Scanning electron micrographs showed that in all of the nanocomposite films, except the Nano-silver-incorporated one, nanoparticles were dispersed homogeneously throughout the chitosan polymer matrix. Consequently, mechanical and barrier properties of chitosan films were affected through intercalation of nanoparticles, that is, tensile strength increased by 7-16%, whereas water vapor permeability decreased by 25-30% depending on the nanoparticle material tested. In addition, chitosan-based nanocomposite films, especially silver-containing ones, showed a promising range of antimicrobial activity. PMID:16881682

Rhim, Jong-Whan; Hong, Seok-In; Park, Hwan-Man; Ng, Perry K W

2006-08-01

97

Effect of carboxymethyl cellulose concentration on physical properties of biodegradable cassava starch-based films  

PubMed Central

Background Cassava starch, the economically important agricultural commodity in Thailand, can readily be cast into films. However, the cassava starch film is brittle and weak, leading to inadequate mechanical properties. The properties of starch film can be improved by adding plasticizers and blending with the other biopolymers. Results Cassava starch (5%w/v) based films plasticized with glycerol (30 g/100 g starch) were characterized with respect to the effect of carboxymethyl cellulose (CMC) concentrations (0, 10, 20, 30 and 40%w/w total solid) and relative humidity (34 and 54%RH) on the mechanical properties of the films. Additionally, intermolecular interactions were determined by Fourier transform infrared spectroscopy (FT-IR), melting temperature by differential scanning calorimetry (DSC), and morphology by scanning electron microscopy (SEM). Water solubility of the films was also determined. Increasing concentration of CMC increased tensile strength, reduced elongation at break, and decreased water solubility of the blended films. FT-IR spectra indicated intermolecular interactions between cassava starch and CMC in blended films by shifting of carboxyl (C = O) and OH groups. DSC thermograms and SEM micrographs confirmed homogeneity of cassava starch-CMC films. Conclusion The addition of CMC to the cassava starch films increased tensile strength and reduced elongation at break of the blended films. This was ascribed to the good interaction between cassava starch and CMC. Cassava starch-CMC composite films have the potential to replace conventional packaging, and the films developed in this work are suggested to be suitable for low moisture food and pharmaceutical products. PMID:21306655

2011-01-01

98

Structure and properties of nanocomposite films based on sodium caseinate and nanocellulose fibers  

Microsoft Academic Search

Films made from sodium caseinate and nanocellulose were prepared by dispersing the fibrils into film forming solutions, casting and drying. Composite films were less transparent and had a more hydrophilic surface than neat sodium caseinate ones. However, the global moisture uptake was almost not affected by filler concentration. Addition of nanocellulose to the neat sodium caseinate films produced an initial

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

99

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

100

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

101

Improvement of the mechanical and barrier properties of methylcellulose-based films by treatment with HEMA and silane monomers under gamma radiation  

NASA Astrophysics Data System (ADS)

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) and water vapor permeability (WVP) of the films were found to be 147 N/mm, 3.46 mm, and 6.34 g mm/m2 day kPa, respectively. The monomer, 2-hydroxyethyl methacrylate (HEMA) (0.1-1%, w/w) was incorporated into the MC-based solution and films were prepared by casting. Films were then exposed to gamma radiation (5-25 kGy) and it revealed that 1% HEMA containing films showed the highest PS values (282 N/mm at 10 kGy). Silane monomer (3-aminopropyl tri-ethoxy silane) (0.1-1%, w/w) was also added into the MC-based films and were found to improve the strength of the films significantly. In comparison between HEMA and silane treatment onto MC-based films, it was observed that silane performed better strength and barrier properties. Surface morphology of the monomer treated films was examined by scanning electron microscopy and suggested better appearance than MC-based film.

Khan, Ruhul A.; Dussault, Dominic; Salmieri, Stephane; Safrany, Agnes; Lacroix, Monique

2012-08-01

102

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

103

A domain partitioning based pre-processor for multi-scale modelling of cast aluminium alloys  

NASA Astrophysics Data System (ADS)

In this paper, a microstructural morphology based domain partitioning MDP methodology is developed for materials with non-uniform heterogeneous microstructure. The comprehensive set of methods is intended to provide a concurrent multi-scale analysis model with an initial computational domain that delineates regions of statistical homogeneity and inhomogeneity. The MDP methodology is intended to be a pre-processor to multi-scale analysis of mechanical behaviour and damage of heterogeneous materials, e.g. cast aluminium alloys. It introduces a systematic three-step process that is based on geometric features of morphology. The first step simulates high resolution microstructural information from low resolution micrographs of the material and a limited number of high resolution optical or scanning electron microscopy micrographs. The second step is quantitative characterization of the high resolution images to create effective metrics that can relate microstructural descriptors to material behaviour. The third step invokes a partitioning method to demarcate regions belonging to different length scales in a concurrent multi-scale model. Partitioning criteria for domain partitioning are defined in terms of microstructural descriptors and their functions. The effectiveness of these metrics in differentiating microstructures of a 319-type cast aluminium alloy with different secondary dendrite arm spacings SDAS is demonstrated. The MDP method establishes intrinsic material length scales for the different SDAS, namely, 23, 70 and 100 µm, and consequently subdivides the computational domain for concurrently coupling macro- and micromechanical analyses in the multi-scale model.

Ghosh, Somnath; Valiveti, D. M.; Harris, Stephen J.; Boileau, James

2006-12-01

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

Microstructure-based fatigue life prediction for cast A356-T6 aluminum-silicon alloys  

NASA Astrophysics Data System (ADS)

Fatigue life prediction and optimization is becoming a critical issue affecting the structural applications of cast aluminum-silicon alloys in the aerospace and automobile industries. In this study, a range of microstructure and porosity populations in A356 alloy was created by controlling the casting conditions and by applying a subsequent hot isostatic pressing (“hipping”) treatment. The microstructure and defects introduced during the processing were then quantitatively characterized, and their effects on the fatigue performance were examined through both experiment and modeling. The results indicated that whenever a pore is present at or near the surface, it initiates fatigue failure. In the absence of large pores, a microcell consisting of ?-Al dendrites and associated Si particles was found to be responsible for crack initiation. Crack initiation life was quantitatively assessed using a local plastic strain accumulation model. Moreover, the subsequent crack growth from either a pore or a microcell was found to follow a small-crack propagation law. Based on experimental observation and finite-element analysis, a unified model incorporating both the initiation and small crack growth stages was developed to quantitatively predict the dependency of fatigue life on the microstructure and porosity. Good agreement was obtained between the model and experiment.

Yi, J. Z.; Gao, Y. X.; Lee, P. D.; Lindley, T. C.

2006-04-01

106

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

107

Preparation of nano cellulose fibers and its application in kappa-carrageenan based film.  

PubMed

Bio-based nanocomposite films were successfully developed using nanofibrillated cellulose (NFC) as the reinforcing phase and kappa-carrageenan (KCRG) as the matrix. NFC was successfully synthesis from short stable cotton fibers by chemo-mechanical process. The bionanocomposites were prepared by incorporating 0.1, 0.2, 0.3, 0.4, 0.5, and 1wt% of the NFC into a KCRG matrix using a solution casting method there characterization was done in terms of thermal properties (DSC), morphology (SEM), water vapor transmission rate (WVTR), oxygen transmission rate (OTR), X-ray diffractograms (XRD), and tensile properties. The main conclusion arising from the analysis of the result is that the bionanocomposites containing 0.4wt% of NFC exhibited the highest enhancement in tensile strength it is almost 44% improvement. WVTR and OTR results showed improvement of all nanocomposite film compare to control KCRG film. PMID:22940239

Savadekar, N R; Karande, V S; Vigneshwaran, N; Bharimalla, A K; Mhaske, S T

2012-12-01

108

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

109

Preparation and Characterization of Films Based on Alginate and Aloe Vera  

Microsoft Academic Search

Sodium alginate films with aloe vera extract were prepared by the casting\\/solvent evaporation technique. The resulting films were characterized by differential scanning calorimetry, Fourier transform-infrared spectroscopy, scanning electron microscopy, and mechanical and water absorption tests. The in vitro degradation of the films was also investigated over 14 days. Results show that aloe vera contributes to both enhancing the thermal and

Rúben Pereira; Ana Tojeira; Daniela C. Vaz; Ausenda Mendes; Paulo Bártolo

2011-01-01

110

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

111

Particle swarm optimization based tuning of a modified smith predictor for mould level control in continuous casting  

Microsoft Academic Search

Mould level variations are a serious productivity and quality problem in continuous casting process. This work proposes a level control structure based on the Aström's modified Smith predictor able to improve the bulging effect rejection. Unlike conventional methods, this control strategy decouples the disturbance rejection from the setpoint response and therefore can be independently optimized. Using this scheme, the bulging

Karim Jabri; Didier Dumur; Emmanuel Godoy; Alain Mouchette; Bertrand Bèle

2011-01-01

112

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...

113

A general and Robust Ray-Casting-Based Algorithm for Triangulating Surfaces at the Nanoscale  

PubMed Central

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

114

Pentacene-based dendrimers: synthesis and thin film photoconductivity measurements of branched pentacene oligomers.  

PubMed

The synthesis of pentacene-based dendrimers has been achieved via esterification of 1,3,5-benzenetricarboxylic acid and unsymmetrical pentacene 4 possessing a hydroxy group. Dendrimers 1 (C(183)H(204)O(9)Si(9), 2800 g mol(-1)) and 2 (C(540)H(570)O(30)Si(24), 8214 g mol(-1)) are characterized by (1)H and (13)C NMR, IR, UV-vis, and fluorescence spectroscopy, as well as mass spectrometry. These branched oligomeric materials are benchtop stable and soluble in common organic solvents, allowing for solution cast formation of thin films. Photocurrent and photocurrent yield measurements of these films reveal improved efficiency in photogenerated conduction for dendrimers in comparison to linearly connected pentacene-based polymers. PMID:19489566

Lehnherr, Dan; Gao, Jianbo; Hegmann, Frank A; Tykwinski, Rik R

2009-07-17

115

A comparative study on microgap of premade abutments and abutments cast in base metal alloys.  

PubMed

The study compared the marginal accuracy of premade and cast abutments. Premade titanium, stainless steel, and gold abutments formed the control groups. Plastic abutments were cast in nickel-chromium, cobalt-chromium and grade IV titanium. The abutment/implant interface was analyzed. Analysis of variance and Duncan's multiple range test revealed no significant difference in mean marginal microgap between premade gold and titanium abutments and between premade stainless steel and cast titanium abutments. Statistically significant differences (P < .001) were found among all other groups. PMID:24914909

Lalithamma, Jaini Jaini; Mallan, Sreekanth Anantha; Murukan, Pazhani Appan; Zarina, Rita

2014-06-01

116

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

117

-Based Mold Flux and Their Effects on In-Mold Performance during High-Aluminum TRIP Steels Continuous Casting  

NASA Astrophysics Data System (ADS)

Crystallization behaviors of the newly developed lime-alumina-based mold fluxes for high-aluminum transformation induced plasticity (TRIP) steels casting were experimentally studied, and compared with those of lime-silica-based mold fluxes. The effects of mold flux crystallization characteristics on heat transfer and lubrication performance in casting high-Al TRIP steels were also evaluated. The results show that the crystallization temperatures of lime-alumina-based mold fluxes are much lower than those of lime-silica-based mold fluxes. Increasing B2O3 addition suppresses the crystallization of lime-alumina-based mold fluxes, while Na2O exhibits an opposite effect. In continuous cooling of lime-alumina-based mold fluxes with high B2O3 contents and a CaO/Al2O3 ratio of 3.3, faceted cuspidine precipitates first, followed by needle-like CaO·B2O3 or 9CaO·3B2O3·CaF2. In lime-alumina-based mold flux with low B2O3 content (5.4 mass pct) and a CaO/Al2O3 ratio of 1.2, the formation of fine CaF2 takes place first, followed by blocky interconnected CaO·2Al2O3 as the dominant crystalline phase, and rod-like 2CaO·B2O3 precipitates at lower temperature during continuous cooling of the mold flux. In B2O3-free mold flux, blocky interconnected 3CaO·Al2O3 precipitates after CaF2 and 3CaO·2SiO2 formation, and takes up almost the whole crystalline fraction. The casting trials show that the mold heat transfer rate significantly decreases near the meniscus during the continuous casting using lime-alumina-mold fluxes with higher crystallinity, which brings a great reduction of surface depressions on cast slabs. However, excessive crystallinity of mold flux causes poor lubrication between mold and solidifying steel shell, which induces various defects such as drag marks on cast slab. Among the studied mold fluxes, lime-alumina-based mold fluxes with higher B2O3 contents and a CaO/Al2O3 ratio of 3.3 show comparatively improved performance.

Shi, Cheng-Bin; Seo, Myung-Duk; Cho, Jung-Wook; Kim, Seon-Hyo

2014-06-01

118

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

119

Biphasic calcium phosphate coating on cobalt-base surgical alloy during investment casting.  

PubMed

The biphasic calcium phosphate (BCP) yields higher bioactivity and efficiency than the Hydroxyapatite (HA) alone. The HA/?-TCP ratio significantly affects BCP bioactivity as well as the extent of BCP resorption. In this study, the BCP coating on ASTM F-75 cobalt base alloy during the investment casting process was investigated. For this purpose, molten metal was poured at 1,470°C into previously coated investment molds preheated to 750, 850, 950, 1,050°C in order to investigate the effect of mold preheating temperatures on coating phase transformations. For in vitro evaluation, samples were immersed in the simulated body fluid (SBF) at 37°C for 4 weeks and characterized by XRD, SEM, EDS, and optical microscopy. The weight percentages of HA and ?-TCP of the specimens were calculated to find that the HA/?-TCP ratio significantly depended on the mold preheating temperature as it caused changes in the dissolution behavior of BCP coating and the bone-like apatite precipitation on coating during in vitro evaluation. PMID:21894538

Minouei, H; Meratian, M; Fathi, M H; Ghazvinizadeh, H

2011-11-01

120

[Flow of molten metal in denture base in horizontal centrifugal casting procedure. (Part 1) Flow, inflow volume and casting time of molten metal passing through single aprue into disk type mold (author's transl)].  

PubMed

A pyrex glass plate was fitted at the bottom of casting ring, and disk type wax pattern (thickness. 0.43 mm) was put on the plate. Five types of sprueing were applied. Pure tin was casted using holizontal centrifugal casting machine. Flow of molten metal was filmed by the motor drive camera with the method of stroboscope. The results were summarized as follows. 1) When the sprue was attached at the center of the disk type mold vertically, moten metal flowed like a concentric circle at the early stage of casting. It was affected gradually by the direction of gravity and revolution, and it filled the mold from the lower part to the upper part. 2) When the sprue gate was attached to the side edge of the mold, and the sprue gate was placed to the forward and backward direction against the revolution direction, molten metal filled from lower part to the upper part. 3) When the sprue gate was placed against upper edge, molten metal flow was affected by the direction of gravity and revolution. When the sprue gate was placed against lower edge, molten metal filled quietry from the lower part to the upper part. 4) Inflow volume per unit time (inflow rate) was small at the early stage of casting. Inflow rate increased and became constant at the next stage. At the latter stage it became small again. 5) Inflow rate increased with the increase of area of sprue. 6) The time which was necessary to fill the volume of 1 cm (about 80% of the mold volume) became short with the increase of area of sprue. It was also influenced by the type of sprueing. PMID:772141

Okamura, H

1976-01-01

121

Structurally Based Assessment of the Influence of Fluorides on the Characteristics of Continuous Casting Powder Slags  

NASA Astrophysics Data System (ADS)

The use of fluorides in continuous casting powder leads to the desired reduction of melting temperature to less than 1573 K (1300 °C) as well as to lowering the viscosity below 10 dPas. With an equilateral use of alkalis, the tendency to form volatile fluorine compounds rises. The effect of these components on the structure of the casting slags can be described with the NBO/T-ratio. Should the full effect of fluorides to be used for structural modification of the slags, the other components have to be inhibited by compound formation so as to prevent them from forming gaseous fluoride. If the fluoride content in the continuous casting slag is represented by means of fluorspar, the influence on the NBO/T-ratio can be described with the impact factor 4.0.

Schulz, Tilo; Lychatz, Bernd; Haustein, Nicole; Janke, Dieter

2013-04-01

122

Probabilistic simulation of hydrogen gas porosity formation in A356 base hypoeutectic alloy castings  

NASA Astrophysics Data System (ADS)

Microporosity in cast aluminum alloy can be classified as gas porosity and/or shrinkage porosity. In prior research, two dimensional simulation programs employing a probabilistic modeling approach and cellular automaton method were developed to predict microporosity in cast aluminum alloys. In this research the 2D models were statistically compared with experimental data. Additionally, we investigated size and morphology distribution of grains and porosity in A356 alloy castings under variable hydrogen content and alloy treatment condition, i.e. eutectic phase modification and grain refinement. In order to improve the accuracy of the prediction method, new simulation models including a two and half dimensional analysis and a two phase evolution model were developed in the present body of work. The new models were statistically compared with experimental results changing silicon and hydrogen content and alloy treatment conditions. The new simulation technique exhibits improved agreement with experimental data tracking the morphology of gas porosities and the grain size distribution.

Asada, Jo

123

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

124

Microstructure Based Modeling of ? Phase Influence on Mechanical Response of Cast AM Series Mg Alloys  

SciTech Connect

Magnesium alloys have become popular alternatives to aluminums and steels for the purpose of vehicle light-weighting. However, Mg alloys are hindered from wider application due to limited ductility as well as poor creep and corrosion performance. Understanding the impact of microstructural features on bulk response is key to improving Mg alloys for more widespread use and for moving towards truly predicting modeling capabilities. This study focuses on modeling the intrinsic features, particularly volume fraction and morphology of beta phase present, of cast Mg alloy microstructure and quantifying their impact on bulk performance. Computational results are compared to experimental measurements of cast plates of Mg alloy with varying aluminum content.

Barker, Erin I.; Choi, Kyoo Sil; Sun, Xin; Deda, Erin; Allison, John; Li, Mei; Forsmark, Joy; Zindel, Jacob; Godlewski, Larry

2014-09-30

125

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

126

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...

127

Energy-Saving Melting and Revert Reduction Technology (E-SMARRT): Lost Foam Thin Wall - Feasibility of Producing Lost Foam Castings in Aluminum and Magnesium Based Alloys  

SciTech Connect

With the increased emphasis on vehicle weight reduction, production of near-net shape components by lost foam casting will make significant inroad into the next-generation of engineering component designs. The lost foam casting process is a cost effective method for producing complex castings using an expandable polystyrene pattern and un-bonded sand. The use of un-bonded molding media in the lost foam process will impose less constraint on the solidifying casting, making hot tearing less prevalent. This is especially true in Al-Mg and Al-Cu alloy systems that are prone to hot tearing when poured in rigid molds partially due to their long freezing range. Some of the unique advantages of using the lost foam casting process are closer dimensional tolerance, higher casting yield, and the elimination of sand cores and binders. Most of the aluminum alloys poured using the lost foam process are based on the Al-Si system. Very limited research work has been performed with Al-Mg and Al-Cu type alloys. With the increased emphasis on vehicle weight reduction, and given the high-strength-to-weight-ratio of magnesium, significant weight savings can be achieved by casting thin-wall (? 3 mm) engineering components from both aluminum- and magnesium-base alloys.

Fasoyinu, Yemi [CanmetMATERIALS] [CanmetMATERIALS; Griffin, John A. [University of Alabama - Birmingham] [University of Alabama - Birmingham

2014-03-31

128

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

129

High-dose film dosimeters based on bromophenol blue or xylenol orange dyed polyvinyl alcohol  

Microsoft Academic Search

Dyed poly(vinyl alcohol) (PVA) films, prepared by a simple technique of casting acqueous solutions of PVA containing bromophenol blue (BPB) or xylenol orange (XYO) on a horizontal glass plate, are useful as routine high-dose dosimeters. These flexible plastic film dosimeters are bleached when exposed to ?-ray photons. Absorbed doses should not exceed 20 kGy for BPB\\/PVA film and 90 kGy

A. A. Abdel-Fattah; S. Ebraheem; M. El-Kelany; F. Abdel-Rehim

1996-01-01

130

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

131

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

132

Optimization of excess Bi doping to enhance ferroic orders of spin casted BiFeO{sub 3} thin film  

SciTech Connect

Multiferroic Bismuth Ferrite (BiFeO{sub 3}) 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 BiFeO{sub 3} 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 BiFeO{sub 3} and Fe{sub 2}O{sub 3} to pure BiFeO{sub 3} phase and, subsequently, to a mixture of BiFeO{sub 3} and Bi{sub 2}O{sub 3} with increase in the concentration of excess Bi from 0% to 15%. BiFeO{sub 3} thin films having low content (0% and 2%) of excess Bi showed the traces of ferromagnetic phase (?-Fe{sub 2}O{sub 3}). Deterioration in ferroic properties of BiFeO{sub 3} thin films is also observed when prepared with higher content (15%) of excess Bi. Single-phased BiFeO{sub 3} thin film prepared with 5% excess Bi concentration exhibited the soft ferromagnetic hysteresis loops and ferroelectric characteristics with remnant polarization 4.2??C/cm{sup 2} 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 BiFeO{sub 3} thin films having 5% excess Bi. The results are important to identify optimum excess Bi concentration needed for the formation of single phase BiFeO{sub 3} thin films exhibiting the improved multiferroic properties.

Gupta, Surbhi; Gupta, Vinay, E-mail: drguptavinay@gmail.com [Department of Physics and Astrophysics, University of Delhi, Delhi (India); Tomar, Monika [Department of Physics, Miranda Housea, University of Delhi, Delhi (India); James, A. R. [Defence Metallurgical Research Laboratory, Hyderabad (India); Pal, Madhuparna; Guo, Ruyan; Bhalla, Amar [Department of Electrical and Computer Engineering, College of Engineering, University of Texas at SanAntonio, San Antonio 78249 (United States)

2014-06-21

133

Influence of film structure and light on charge trapping and dissipation dynamics in spun-cast organic thin-film transistors measured by scanning Kelvin probe microscopy  

NASA Astrophysics Data System (ADS)

Herein, time-dependent scanning Kelvin probe microscopy of solution processed organic thin film transistors (OTFTs) reveals a correlation between film microstructure and OTFT device performance with the location of trapped charge within the device channel. The accumulation of the observed trapped charge is concurrent with the decrease in ISD during operation (VG = -40 V, VSD = -10 V). We discuss the charge trapping and dissipation dynamics as they relate to the film structure and show that application of light quickly dissipates the observed trapped charge.

Teague, L. C.; Loth, M. A.; Anthony, J. E.

2012-06-01

134

Real-Time, Model-Based Spray-Cooling Control System for Steel Continuous Casting  

Microsoft Academic Search

This article presents a new system to control secondary cooling water sprays in continuous casting of thin steel slabs (CONONLINE).\\u000a It uses real-time numerical simulation of heat transfer and solidification within the strand as a software sensor in place\\u000a of unreliable temperature measurements. The one-dimensional finite-difference model, CON1D, is adapted to create the real-time\\u000a predictor of the slab temperature and

Bryan Petrus; Kai Zheng; X. Zhou; Brian G. Thomas; Joseph Bentsman

2011-01-01

135

Resistivity-Based Evaluation of the Fatigue Behavior of Cast Irons  

NASA Astrophysics Data System (ADS)

Cast irons are used in particular for highly stressed components in the automotive and commercial vehicle industry, e.g., for crankcases and in the wind power industry, e.g., for rotor hubs. The mechanical properties of cast irons are strongly influenced by parameters like phase composition of the matrix, graphite shape, micro-pinholes, and micro-cracks. The measurement of the electrical resistance in the unloaded state and its change during cyclic loading offers the possibility to get detailed information about the actual defect density and the cyclic deformation behavior. In the scope of the present work, stress-controlled load increase tests and constant amplitude tests were carried out at ambient temperature with specimens of the perlitic cast irons EN-GJL-250 (ASTM A48 35B), EN-GJV-400, and EN-GJS-600 (ASTM 80-55-06). Beside electrical measurements, scanning electron microscopy (SEM) was used to characterize the microstructure and to correlate the change of microstructural details with cyclic properties.

Germann, Holger; Starke, Peter; Eifler, Dietmar

2012-08-01

136

Carbon nanotube based nanostructured thin films: preparation and application  

NASA Astrophysics Data System (ADS)

Hybrid thin films of multi-walled carbon nanotube (MWCNT) and titania were fabricated on quartz slides by alternatively depositing MWCNT and titanium(IV) bis(ammonium lactato) dihydroxide (TALH) via a solution based layer-by-layer (LbL) self-assembly method followed by calcination to convert TALH to crystalline titania. The multilayer film build-up was monitored by UV-vis spectroscopy which indicated the linear growth of the film with the bilayer number. XRD confirmed the formation of anantase titania after heat treatment. The photocatalytic property of the hybrid thin film was evaluated by its capacity to degrade rhodamine B under the UV illumination. Compared with pure TiO2 film, experiments showed that the MWCNT/TiO2 hybrid film had a much higher photocatalytic activity under the same conditions. The first order rate constant of photocatalysis of 30 bilayers of hybrid film was approximately 8-fold higher than that of 30 bilayers of pure TiO2 film. In addition, the degradation efficiency of MWCNT/TiO2 hybrid thin film increased with its thickness while pure titania film remained unchanged. A 30 bilayers hybrid thin film that contains about 0.2 mg MWCNT/TiO2 catalyst was capable of completely degrading 10 mL of 2 mg/L Rh B solution within 5 hours. The results also indicated that the hybrid catalyst could be reused for several cycles.

Fu, Li; Yu, Aimin

2013-08-01

137

Effect of Carboxymethylcellulose and Plasticizer Concentration on Wetting and Mechanical Properties of Cashew Tree Gum–Based Films  

Microsoft Academic Search

The combination of carboxymethylcellulose (CMC), cashew tree gum and, glycerol as plasticizer was evaluated in the formation and properties of films processed by casting. CMC acts as both a gelling and film-formation agent, yielding samples with reasonable mechanical properties. Increasing the concentration of CMC increased tensile strength, reduced elongation at break, and decreased wettability of the blended films. Microscopy surface

Douglas de Britto; Jackeline S. de Rizzo; Odilio B. G. Assis

2012-01-01

138

Integrated thick-film nanostructures based on spinel ceramics  

PubMed Central

Integrated temperature-humidity-sensitive thick-film structures based on spinel-type semiconducting ceramics of different chemical compositions and magnesium aluminate ceramics were prepared and studied. It is shown that temperature-sensitive thick-film structures possess good electrophysical characteristics in the region from 298 to 358 K. The change of electrical resistance in integrated thick-film structures is 1 order, but these elements are stable in time and can be successfully used for sensor applications. PMID:24670141

2014-01-01

139

Effects of silicon on the oxidation, hot-corrosion, and mechanical behavior of two cast nickel-base superalloys  

Microsoft Academic Search

Cast specimens of nickel-base superalloys 713C and Mar-M200 with nominal additions of 0, 0.5, and 1 wt pct Si were evaluated\\u000a for oxidation and corrosion resistance, tensile and stress-rupture properties, microstructure, and phase relations. Results\\u000a are com-pared with those of an earlier study of the effects of Si in B-1900. Si had similar effects on all three superalloys.\\u000a It improves

Robert V. Miner

1977-01-01

140

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

141

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

142

Electrocaloric devices based on thini-film heat switches  

SciTech Connect

We describe a new approach to refrigeration and electrical generation that exploits the attractive properties of thin films of electrocaloric materials. Layers of electrocaloric material coupled with thin-film heat switches can work as either refrigerators or electrical generators, depending on the phasing of the applied voltages and heat switching. With heat switches based on thin layers of liquid crystals, the efficiency of these thin-film heat engines can be at least as high as that of current thermoelectric devices. Advanced heat switches would enable thin-film heat engines to outperform conventional vaporcompression devices.

Epstein, Richard I [Los Alamos National Laboratory; Malloy, Kevin J [UNM

2009-01-01

143

Microelectromechanical switches based on amorphous diamondlike carbon films  

NASA Astrophysics Data System (ADS)

We report on the development and investigation of radio frequency (RF) switches (including complete relay pairs) that employ single-crystal microelectromechanical systems (MEMSs) with mobile elements based on high-ohmic amorphous diamondlike carbon films. The use of these films in RF-MEMS switches eliminates problems related to electrode sticking, significantly decreases signal losses (to 100 dB), and ensures short switching times (˜10 ns) for commutated signals at ultrahigh frequencies (up to 2 GHz for films on silicon substrates and above 10 GHz for films on gallium arsenide substrates).

Vlasenko, V. A.; Belyaev, S. N.; Efimov, A. G.; Il'Ichev, É. A.; Malenkovich, M. D.; Nemirovski?, V. É.; Poltoratski?, É. A.; Goryachev, A. V.; Popkov, A. F.; Frolova, G. V.; Shupegin, M. L.

2009-08-01

144

Electrocaloric devices based on thin-film heat switches  

NASA Astrophysics Data System (ADS)

We describe a new approach to refrigeration, heat pumping, and electrical generation that allows one to exploit the attractive properties of thin films of electrocaloric materials. Layers of electrocaloric material coupled with thin-film heat switches can work as either refrigerators and heat pumps or electrical generators, depending on the phasing of the applied voltages and heat switching. With heat switches based on thin layers of liquid crystals, the efficiency of electrocaloric thin-film devices can be at least as high as that of current thermoelectric devices. Advanced heat switches that may use carbon nanotubes would enable thin-film refrigerators and generators to outperform conventional vapor-compression devices.

Epstein, Richard I.; Malloy, Kevin J.

2009-09-01

145

FILM E COPERTURE EDULI CON MATRICI A BASE DI FRUTTA  

Technology Transfer Automated Retrieval System (TEKTRAN)

Films based on pear puree were formed using thermal compression molding. Whey protein isolates and soy protein isolates were added to these films to improve their processing and strength. The effects of pear puree concentration, whey or soy protein concentration, moisture content and sorbitol cont...

146

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

147

PHB-based films as matrices for pesticides  

Microsoft Academic Search

The effects of pesticides incorporated into PHB-based polymeric matrices on the biodegradability of films and antifungal efficiency of immobilised pesticides to Botrytis cinerea was studied. The mass loss of tested PHB-based films for 2 weeks was 40–50% and after 4 weeks 92–96% of the initial mass. The fungicides Ronilan and Sumilex immobilised into the polymeric matrices did not depress the

L Savenkova; Z Gercberga; O Muter; V Nikolaeva; A Dzene; V Tupureina

2002-01-01

148

Exciton dynamics reveal aggregates with intermolecular order at hidden interfaces in solution-cast organic semiconducting films  

NASA Astrophysics Data System (ADS)

Large-scale organic electronics manufacturing requires solution processing. For small-molecule organic semiconductors, solution processing results in crystalline domains with high charge mobility, but the interfaces between these domains impede charge transport, degrading device performance. Although understanding these interfaces is essential to improve device performance, their intermolecular and electronic structure is unknown: they are smaller than the diffraction limit, are hidden from surface probe techniques, and their nanoscale heterogeneity is not typically resolved using X-ray methods. Here we use transient absorption microscopy to isolate a unique signature of a hidden interface in a TIPS-pentacene thin film, exposing its exciton dynamics and intermolecular structure. Surprisingly, instead of finding an abrupt grain boundary, we reveal that the interface can be composed of nanoscale crystallites interleaved by a web of interfaces that compound decreases in charge mobility. Our novel approach provides critical missing information on interface morphology necessary to correlate solution-processing methods to optimal device performance.

Wong, Cathy Y.; Cotts, Benjamin L.; Wu, Hao; Ginsberg, Naomi S.

2015-01-01

149

Exciton dynamics reveal aggregates with intermolecular order at hidden interfaces in solution-cast organic semiconducting films.  

PubMed

Large-scale organic electronics manufacturing requires solution processing. For small-molecule organic semiconductors, solution processing results in crystalline domains with high charge mobility, but the interfaces between these domains impede charge transport, degrading device performance. Although understanding these interfaces is essential to improve device performance, their intermolecular and electronic structure is unknown: they are smaller than the diffraction limit, are hidden from surface probe techniques, and their nanoscale heterogeneity is not typically resolved using X-ray methods. Here we use transient absorption microscopy to isolate a unique signature of a hidden interface in a TIPS-pentacene thin film, exposing its exciton dynamics and intermolecular structure. Surprisingly, instead of finding an abrupt grain boundary, we reveal that the interface can be composed of nanoscale crystallites interleaved by a web of interfaces that compound decreases in charge mobility. Our novel approach provides critical missing information on interface morphology necessary to correlate solution-processing methods to optimal device performance. PMID:25581561

Wong, Cathy Y; Cotts, Benjamin L; Wu, Hao; Ginsberg, Naomi S

2015-01-01

150

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

151

Education and Caste in India  

ERIC Educational Resources Information Center

This paper analyses the policy of reservation for lower castes in India. This policy is similar to that of affirmative action in the United States. The paper provides a brief overview of the caste system and discusses the types of groups that are eligible for reservation, based on data from government reports. The stance of this paper is that…

Chauhan, Chandra Pal Singh

2008-01-01

152

Aroma barrier properties of sodium caseinate-based films.  

PubMed

The mass transport of six different aroma compounds (ethyl acetate, ethyl butyrate, ethyl hexanoate, 2-hexanone, 1-hexanol, and cis-3-hexenol) through sodium caseinate-based films with different oleic acid (OA)/beeswax (BW) ratio has been studied. OA is less efficient than BW in reducing aroma permeability, which can be attributed to its greater polarity. Control film (without lipid) and films prepared with 0:100 OA/BW ratio show the lowest permeability. OA involves a decrease in aroma barrier properties of the sodium caseinate-based films due to its plasticization ability. Preferential sorption and diffusion occurs through OA instead of caseinate matrix and/or BW. The efficiency of sodium caseinate-based films to retain or limit aroma compound transfers depend on the affinity of the volatile compound to the films, which relates physicochemical interaction between volatile compound and film. Specific interactions (aroma compound-hydrocolloid and aroma compound-lipid) induce structural changes during mass transfer. PMID:18361517

Fabra, Maria José; Hambleton, Alicia; Talens, Pau; Debeaufort, Fréderic; Chiralt, Amparo; Voilley, Andrée

2008-05-01

153

Nanocrystalline silicon based thin film solar cells  

NASA Astrophysics Data System (ADS)

Amorphous silicon solar cells and panels on glass and flexible substrate are commercially available. Since last few years nanocrystalline silicon thin film has attracted remarkable attention due to its stability under light and ability to absorb longer wavelength portion of solar spectrum. For amorphous silicon/ nanocrystalline silicon double junction solar cell 14.7% efficiency has been achieved in small area and 13.5% for large area modules internationally. The device quality nanocrystalline silicon films have been fabricated by RF and VHF PECVD methods at IACS. Detailed characterizations of the materials have been done. Nanocrystalline films with low defect density and high stability have been developed and used as absorber layer of solar cells.

Ray, Swati

2012-06-01

154

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

155

Preparation, characterization and in vitro evaluation of a polyvinyl alcohol/sodium alginate based orodispersible film containing sildenafil citrate.  

PubMed

In this work, we developed a sildenafil citrate (SC)-loaded polyvinyl alcohol (PVA)/sodium alginate (ALG-Na) based orodispersible film (ODF) using a solvent casting method. Formulation factors such as the type and amount of plasticizers and disintegrants were optimized on the basis of characteristics of blank ODF, including the disintegration time, elastic modulus (EM) and percentage of elongation (E%). SC-loaded ODF with a loading capacity up to 25 mg in an area of 6 cm2 was prepared and evaluated in terms of mechanical properties, disintegration time and dissolution rate. The surface morphology of ODF was visualized under a scanning electron microscope (SEM). The physicochemical properties of ODF were investigated using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The blank ODF composed of PVA, polyethylene glycol 400 (PEG 400) and ALG-Na (20:5:2, w/w) had a remarkably short disintegration time of about 20 s. However, the loading of drug extended the disintegration time (100 s) of ODF, while it still maintained satisfactory mechanical properties. SC was homogenously dispersed throughout the films and the crystalline form of drug changed, with strong hydrogen bonding between the drug and carriers. The PVA/ALG-Na based ODF containing SC prepared by the simple solvent casting method might be an alternative to conventional SC tablets for the treatment of male erectile dysfunction. PMID:24855822

Shi, Li-Li; Xu, Wei-Juan; Cao, Qing-Ri; Yang, Mingshi; Cui, Jing-Hao

2014-05-01

156

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

157

Interfacial characteristics of squeeze-cast SiC reinforced AZ91D magnesium-based composites  

SciTech Connect

The method of producing magnesium-based composites with silicon carbide (SiC) particulates embedded in the matrix of magnesium AZ91D alloy by the squeeze-casting technique are described. This method involves the fabrication of a SiC particulate preform and the subsequent squeezing of molten magnesium into the preform. In this study, alumina, aluminum phosphate and a proprietary binder were used for the fabrication of SiC particulate preforms. The procedures employed in the fabrication of SiC/AZ91D composites are presented, together with the results of characterization of the composites using optical and transmission electron microscopy. Special attention is given to the reaction products in the bulk alloy and at the interfaces between SiC particles and the AZ91D matrix alloy.

Lo, J.; Carpenter, G.J.C.; Charest, M. [MTL/CANMET, Ottawa, Ontario (Canada)

1996-10-01

158

High-temperature superconducting thin-film-based electronic devices  

SciTech Connect

This the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project involved optimization of processing of Y123 and Tl-2212 thin films deposited on novel substrates for advanced electronic devices. The Y123 films are the basis for development of Josephson Junctions to be utilized in magnetic sensors. Microwave cavities based on the Tl-2212 films are the basis for subsequent applications as communication antennas and transmitters in satellites.

Wu, X.D; Finokoglu, A.; Hawley, M.; Jia, Q.; Mitchell, T.; Mueller, F.; Reagor, D.; Tesmer, J.

1996-09-01

159

Active microcantilevers based on piezoresistive ferromagnetic thin films  

NASA Astrophysics Data System (ADS)

We report the piezoresistivity in magnetic thin films of Fe0.7Ga0.3 and their use for fabricating self-transducing microcantilevers. The actuation occurs as a consequence of both the ferromagnetic and magnetostrictive properties of Fe0.7Ga0.3 thin films, while the deflection readout is achieved by exploiting the piezoresistivity of these films. This self-sensing self-actuating micromechanical system involves a very simple bilayer structure, which eliminates the need for the more complex piezoelectric stack that is commonly used in active cantilevers. Thus, it potentially opens opportunities for remotely actuated cantilever-based sensors.

Bhaskaran, Harish; Li, Mo; Garcia-Sanchez, Daniel; Zhao, Peng; Takeuchi, Ichiro; Tang, Hong X.

2011-01-01

160

Wetting properties at the surface of iota-carrageenan-based edible films.  

PubMed

Surface properties of edible films composed of a polymeric matrix of carrageenan in association with hydrophobic material were studied by contact angle measurements. The use of this technique not only in a static mode but also in a dynamic way enables investigation of surface hydrophobicity as well as surface wettability. The absorption flux inside the material can be estimated from the wetting kinetic, which can be very useful to quickly compare water barrier efficiency of the tested films. Comparison of carrageenan films with films containing known amounts of additives enables understanding and correlation of changes of the surface properties with the nature of used additives (glycerol used as a plasticizer, glycerol monostearate used as a surfactant, and fat) and their influence on the orientation of polymer chains at the surface during film formation. Very different responses were observed from one surface of the film (film-casting-support interface) to the other (film-air interface), which could be also attributed to the influence of the support on the polymer and to macromolecular orientation during drying after casting. PMID:16259994

Karbowiak, Thomas; Debeaufort, Frédéric; Champion, Dominique; Voilley, Andrée

2006-02-15

161

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

162

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

163

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

164

Volume ray casting is based on sampling the data along sight rays. In this technique, reconstruction is achieved by a convolution,  

E-print Network

ABSTRACT Volume ray casting is based on sampling the data along sight rays. In this technique meth- ods such as early ray termination and bounding volumes, which are methods that traditional voxel volume rendering has emerged as a major technology in many visualization scenarios. A natural choice

Mueller, Klaus

165

O on the Crystallization Behavior of Lime-Alumina-Based Mold Flux for Casting High-Al Steels  

NASA Astrophysics Data System (ADS)

With the development of advanced high strength steel (AHSS), a large amount of aluminum was added into steels. The reaction between aluminum in the molten steel and silica based mold flux in the continuous-casting process would tend to cause a series of problems and influence the quality of slabs. To solve the above problems caused by the slag-steel reaction, nonreactive lime-alumina-based mold flux system has been proposed. In this article, the effect of Li2O and Na2O on the crystallization behavior of the lime-alumina-silica-based mold flux has been studied by using the single hot thermocouple technology (SHTT) and double hot thermocouple technology (DHTT). The results indicated that Li2O and Na2O in the above mold flux system play different roles as they behaved in traditional lime-silica based mold flux, which would tend to inhibit general mold flux crystallization by lowering the initial crystallization temperature and increasing incubation time, especially in the high-temperature region. However, when their content exceeds a critical value, the crystallization process of mold fluxes in low temperature zone would be greatly accelerated by the new phase formation of LiAlO2 and Na x Al y Si z O4 crystals, respectively. The crystalline phases precipitated in all samples during the experiments are discussed in the article.

Lu, Boxun; Chen, Kun; Wang, Wanlin; Jiang, Binbin

2014-08-01

166

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.

167

AtCAST3.0 Update: A Web-Based Tool for Analysis of Transcriptome Data by Searching Similarities in Gene Expression Profiles.  

PubMed

In transcriptome experiments, the experimental conditions (e.g. mutants and/or treatments) cause transcriptional changes. Identifying experimental conditions that induce similar or opposite transcriptional changes can be useful to identify experimental conditions that affect the same biological process. AtCAST (http://atpbsmd.yokohama-cu.ac.jp) is a web-based tool to analyze the relationship between experimental conditions among transcriptome data. Users can analyze 'user's transcriptome data' of a new mutant or a new chemical compound whose function remains unknown to generate novel biological hypotheses. This tool also allows for mining of related 'experimental conditions' from the public microarray data, which are pre-included in AtCAST. This tool extracts a set of genes (i.e. module) that show significant transcriptional changes and generates a network graph to present related transcriptome data. The updated AtCAST now contains data on >7,000 microarrays, including experiments on various stresses, mutants and chemical treatments. Gene ontology term enrichment (GOE) analysis is introduced to assist the characterization of transcriptome data. The new AtCAST supports input from multiple platforms, including the 'Arabisopsis gene 1.1 ST array', a new microarray chip from Affymetrix and RNA sequencing (RNA-seq) data obtained using next-generation sequencing (NGS). As a pilot study, we conducted microarray analysis of Arabidopsis under auxin treatment using the new Affymetrix chip, and then analyzed the data in AtCAST. We also analyzed RNA-seq data of the pifq mutant using AtCAST. These new features will facilitate analysis of associations between transcriptome data obtained using different platforms. PMID:25505006

Kakei, Yusuke; Shimada, Yukihisa

2015-01-01

168

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

169

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

170

Casting materials  

SciTech Connect

A foam material comprises a liquid polymer and a liquid isocyanate which is mixed to make a solution that is poured, injected or otherwise deposited into a corresponding mold. A reaction from the mixture of the liquid polymer and liquid isocyanate inside the mold forms a thermally collapsible foam structure having a shape that corresponds to the inside surface configuration of the mold and a skin that is continuous and unbroken. Once the reaction is complete, the foam pattern is removed from the mold and may be used as a pattern in any number of conventional casting processes.

Chaudhry, Anil R. (Xenia, OH); Dzugan, Robert (Cincinnati, OH); Harrington, Richard M. (Cincinnati, OH); Neece, Faurice D. (Lyndurst, OH); Singh, Nipendra P. (Pepper Pike, OH)

2011-06-14

171

Isotropic and anisotropic dipeptide films based on gas phase deposition  

NASA Astrophysics Data System (ADS)

We demonstrated the fabrication and application of well-ordered and vertically aligned dipeptide nanostructures based on a simple gas phase deposition. Deposited nanostructures exhibited the superhydrophobic property with a very low sliding angle. Highly reproducible SERS data have also been obtained after combining deposited films with a thin layer of gold. In addition to these, directional peptide films were, for the first time, successfully fabricated based on the oblique angle deposition technique. We believe that such bio-inspired materials would have a great impact in several technological applications involving catalysis, tissue engineering and biosensors.

Demirel, Gokhan; Tamer, Ugur

2012-06-01

172

Outdoor degradation of thin film amorphous silicon based PV modules  

NASA Astrophysics Data System (ADS)

One of the main problems in thin film silicon based modules is the deterioration of their performance upon exposure to light. The presented work focuses on a methodology for evaluation of thin-film photovoltaic module degradation behavior under real operating conditions. The outdoor degradation of double junction a-Si:H/a-Si:H modules was investigated using automated measurement setup for a period of two years. A deterioration of the module's maximum power was observed due to the well known Staebler-Wronski effect, which main causes are the decrease of open circuit voltage and the fill factor of the module. The obtained results can be correlated to the technology and construction of the thin film silicon based modules.

Berov, M.; Ivanov, P.; Tuytuyndziev, N.; Vitanov, P.

2014-12-01

173

Reactively sputtered Fe3O4-based films for spintronics  

NASA Astrophysics Data System (ADS)

Half metallic polycrystalline, epitaxial Fe3O4 films and Fe3O4-based heterostructures for spintronics were fabricated by DC reactive magnetron sputtering. Large tunneling magnetoresistance was found in the polycrystalline Fe3O4 films and attributed to the insulating grain boundaries. The pinning effect of the moments at the grain boundaries leads to a significant exchange bias. Frozen interfacial/surface moments induce weak saturation of the high-field magnetoresistance. The films show a moment rotation related butterfly-shaped magnetoresistance. It was found that in the films, natural growth defects, antiphase boundaries, and magnetocrystalline anisotropy play important roles in high-order anisotropic magnetoresistance. Spin injection from Fe3O4 films to semiconductive Si and ZnO was measured to be 45% and 28.5%, respectively. The positive magnetoresistance in the Fe3O4-based heterostructures is considered to be caused by a shift of the Fe3O4 eg ? band near the interface. Enhanced magnetization was observed in Fe3O4/BiFeO3 heterostructures experimentally and further proved by first principle calculations. The enhanced magnetization can be explained by spin moments of the thin BiFeO3 layer substantially reversing into a ferromagnetic arrangement under a strong coupling that is principally induced by electronic orbital reconstruction at the interface.

Li, Peng; Jin, Chao; Mi, Wen-Bo; Bai, Hai-Li

2013-04-01

174

Optical antennas based on coupled nanoholes in thin metal films  

E-print Network

ARTICLES Optical antennas based on coupled nanoholes in thin metal films Y. ALAVERDYAN* , B. SEP, which makes the nanohole chains effectively behave as linear wire antennas. The possibility to control in areas such as integrated nanophotonic circuits6 , optical antennas7,8 , spectroscopy9 , sensing10

Loss, Daniel

175

Dendritic wideband metamaterial absorber based on resistance film  

NASA Astrophysics Data System (ADS)

A type of dendritic wideband metamaterial absorber was designed and constructed from resistance film composed of indium-tin oxide conductive film having a dendritic metamaterial structure, dielectric layer made of polymethacrylimide foam, and metallic sheet based on the equivalent circuit model. In terms of normal incidence, the simulation using the absorber yielded operating absorption rates >80 % in the frequency range of 8-27.9 GHz. In addition, the experimental measurements verified 8-17 GHz range of more than 80 % absorption rate, whereas its relative bandwidth reached 72 %. Moreover, this reasonable absorption performance was maintained for oblique incidences of <60°. The effects of dielectric layer thickness on absorption properties were verified.

Wang, Bing; Gong, Bo Yi; Wang, Mei; Weng, Bin; Zhao, Xiaopeng

2014-12-01

176

Application of variable-metric chaos optimization neural network in predicting slab surface temperature of the continuous casting  

Microsoft Academic Search

A slab surface temperature prediction model of the continuous casting based on the variable-metric chaos optimization neural network is presented to solve the problem which the slab surface temperatures can not be measured continuously directly for plentiful inhalator, water film and ferric oxide on the slab surface in the secondary cooling zone. The model is shown to fit the actual

Fengxiang Gao; Changsong Wang; Yubao Zhang; Xiao Chen

2009-01-01

177

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

178

Structural aspects of corrosion resistance in alloys based on the Fe3Al intermetallic phase in the cast state  

NASA Astrophysics Data System (ADS)

This paper presents the results of investigation of four cast alloys based on the Fe3Al intermetallic phase. Microstructure tests using light microscopy, electron scanning microscopy and X-ray diffraction methods, have been performed. On this basis, a presence of particles rich in zirconium and molybdenum, and in case of the alloy with 28 at.% aluminium and 5 at.% chromium — the presence of sigma phase (FeCr), has been found. Also, the results of the study of the microstructure influence on the electrochemical corrosion resistance in the 5 % NaCl solution have been presented. The Fe-26Al-2Cr-1Mo-0.1Zr-0.005B at.% and Fe-26Al-5Cr-1Mo-0.1Zr-0.005B at.% alloys exhibited increased corrosion resistance in comparison to the Fe-23Al-1Mo-0.1Zr-0.005B at.% alloy without chromium addition. The appearance of the sigma phase in the alloy of Fe-28Al-5Cr-1Mo-0.1Zr-0.005B at.% chemical composition resulted in lowering the corrosion resistance of this alloy and a change in corrosion character from the pitting to the intercrystalline one.

Lachowicz, M. M.; Haimann, K.; Lachowicz, M. B.; Jasionowski, R.; Pawlak, S.

2012-09-01

179

Switchable mirrors based on nickel-magnesium films  

SciTech Connect

A new type of electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin,magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on reduction in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction,and to protect the metal surface against oxidation.

Richardson,Thomas J.; Slack, Jonathan L.; Armitage, Robert D.; Kostecki, Robert; Farangis, Baker; Rubin, Michael D.

2001-01-16

180

A space imaging concept based on a 4m structured spun-cast borosilicate monolithic primary mirror  

NASA Astrophysics Data System (ADS)

Lockheed Martin Corporation (LMC) tasked The University of Arizona Steward Observatory (UASO) to conduct an engineering study to examine the feasibility of creating a 4m space telescope based on mature borosilicate technology developed at the UASO for ground-based telescopes. UASO has completed this study and concluded that existing launch vehicles can deliver a 4m monolithic telescope system to a 500 km circular orbit and provide reliable imagery at NIIRS 7-8. An analysis of such an imager based on a lightweight, high-performance, structured 4m primary mirror cast from borosilicate glass is described. The relatively high CTE of this glass is used to advantage by maintaining mirror shape quality with a thermal figuring method. Placed in a 290 K thermal shroud (similar to the Hubble Space Telescope), the orbit averaged figure surface error is 6nm rms when earth-looking. Space-looking optical performance shows that a similar thermal conditioning scheme combined with a 270 K shroud achieves primary mirror distortion of 10 nm rms surface. Analysis shows that a 3-point bipod mount will provide launch survivability with ample margin. The primary mirror naturally maintains its shape at 1g allowing excellent end-to-end pre-launch testing with e.g. the LOTIS 6.5m Collimator. The telescope includes simple systems to measure and correct mirror shape and alignment errors incorporating technologies already proven on the LOTIS Collimator. We have sketched a notional earth-looking 4m telescope concept combined with a wide field TMA concept into a DELTA IV or ATLAS 552 EELV fairing. We have combined an initial analysis of launch and space performance of a special light-weighted honeycomb borosilicate mirror (areal density 95 kg/m2) with public domain information on the existing launch vehicles.

West, S. C.; Bailey, S. H.; Bauman, S.; Cuerden, B.; Granger, Z.; Olbert, B. H.

2010-07-01

181

Oxygen and oil barrier properties of microfibrillated cellulose films and coatings  

Microsoft Academic Search

The preparation of carboxymethylated microfibrillated cellulose (MFC) films by dispersion-casting from aqueous dispersions\\u000a and by surface coating on base papers is described. The oxygen permeability of MFC films were studied at different relative\\u000a humidity (RH). At low RH (0%), the MFC films showed very low oxygen permeability as compared with films prepared from plasticized\\u000a starch, whey protein and arabinoxylan and

Christian Aulin; Mikael Gällstedt; Tom Lindström

2010-01-01

182

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

183

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

184

Casting-Based Production of Al-TiC-AlB2 Composite Material Through the Use of KBF4 Salt  

NASA Astrophysics Data System (ADS)

High volume fraction TiC-AlB2 reinforced Al composite material has been produced by a casting process based on the use of KBF4 salt. The reaction between the salt compound led to the release of AlB2 precipitates in commercial purity Al melt whereas the improved wettability between the TiC particles and the formed slag caused their spontaneous entry. The resulting double reinforced composite showed no sign of severe TiC dissolution-reaction.

Karantzalis, A. E.; Lekatou, A.; Georgatis, M.; Poulas, V.; Mavros, H.

2011-03-01

185

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

186

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

187

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

188

Informing Selection of Nanomaterial Concentrations for ToxCast in Vitro Testing Based on Occupational Exposure Potential  

PubMed Central

Background: Little justification is generally provided for selection of in vitro assay testing concentrations for engineered nanomaterials (ENMs). Selection of concentration levels for hazard evaluation based on real-world exposure scenarios is desirable. Objectives: Our goal was to use estimates of lung deposition after occupational exposure to nanomaterials to recommend in vitro testing concentrations for the U.S. Environmental Protection Agency’s ToxCast™ program. Here, we provide testing concentrations for carbon nanotubes (CNTs) and titanium dioxide (TiO2) and silver (Ag) nanoparticles (NPs). Methods: We reviewed published ENM concentrations measured in air in manufacturing and R&D (research and development) laboratories to identify input levels for estimating ENM mass retained in the human lung using the multiple-path particle dosimetry (MPPD) model. Model input parameters were individually varied to estimate alveolar mass retained for different particle sizes (5–1,000 nm), aerosol concentrations (0.1 and 1 mg/m3), aspect ratios (2, 4, 10, and 167), and exposure durations (24 hr and a working lifetime). The calculated lung surface concentrations were then converted to in vitro solution concentrations. Results: Modeled alveolar mass retained after 24 hr is most affected by activity level and aerosol concentration. Alveolar retention for Ag and TiO2 NPs and CNTs for a working-lifetime (45 years) exposure duration is similar to high-end concentrations (~ 30–400 ?g/mL) typical of in vitro testing reported in the literature. Conclusions: Analyses performed are generally applicable for providing ENM testing concentrations for in vitro hazard screening studies, although further research is needed to improve the approach. Understanding the relationship between potential real-world exposures and in vitro test concentrations will facilitate interpretation of toxicological results. PMID:21788197

Brown, James S.; Wang, Amy; Houck, Keith A.; Dix, David J.; Kavlock, Robert J.; Hubal, Elaine A. Cohen

2011-01-01

189

Fabrication, Characterization, and Applications of Graphene-based Flexible Films  

NASA Astrophysics Data System (ADS)

Scientific interest in the field of nanotechnology has increased multifold since the discovery of multi-walled carbon nanotubes in the early 1990s. This further received a tremendous boost with the isolation of graphene, a single layer of sp2-hybridized carbon atoms, in 2004. Graphene has exceptional mechanical and electrical properties, which makes it an attractive candidate for electronics and composites. In order to realize the implementation of graphene for such applications, scalable production of graphene-based materials needs to be accomplished. Graphene oxide, the product of oxidation and exfoliation of graphite, is a promising precursor for bulk-production of graphene and graphene-like materials. The oxidation of graphite to synthesize graphene oxide results in the decoration of the basal plane of graphene with oxygen-containing functional groups. The presence of these functional groups makes graphene oxide strongly hydrophilic, making it soluble in water and a good candidate for solution-based processing. This hydrophilic nature of graphene oxide can also be utilized to fabricate highly sensitive and flexible humidity sensors, the results of which are included in this research. The fabricated humidity sensors show high sensitivity and a fast response time. A difference in response is observed at low and high humidity, with hysteresis observed at high humidity levels. A method to "reset" the sensor and a mechanism to explain the response is also proposed. Although the hydrophilic nature of graphene oxide makes it suitable for bulk processing, the presence of functional groups makes it defective and insulating. Graphene oxide needs to be reduced to make it electrically active. Numerous methodologies proposed for reduction of graphene oxide result in the simultaneous reduction and exfoliation of graphene oxide films. But for instances where flexible graphene films are required for certain applications, a method for reduction of graphene oxide flexible films while maintaining its structural integrity is essential. A method for thermal reduction of flexible graphene oxide films under stress confinement is described. Reduction of graphene oxide flexible films is carried out in a MTS testing machine equipped with a controlled atmosphere furnace. The reduced films show higher carbon-to-oxygen ratio and an increase in conductivity by over five orders in magnitude. An electromechanical application of these reduced graphene oxide films for strain sensing is also demonstrated, with high and tunable gauge factors, which are three orders of magnitude higher than conventional metal foil strain gauges. A mechanism and model to explain the strain sensing is also described. Lastly, quantification of the degree of photoreduction and characterization of thermal properties of graphene-based flexible films is conducted. The temperature distribution on the surface of the graphene oxide flexible film is recorded using an infrared thermal camera. Effective reduction using a laser is achieved in a very short duration at low power and temperature. The thermal properties are calculated using the transient temperature response, and are found to be orders of magnitude lower than pristine graphene. The photoreduction method is a promising route for roll-to-roll production of reduced graphene oxide flexible films.

Naik, Gautam

190

Biochemical sensors based on thin-film waveguide  

Microsoft Academic Search

Biochemical sensors based on thin-film waveguide are proposed which can measure the concentration of sample solutions. In order to investigate the applicability of these sensors to Ca2+ and glucose measurement, the waveguide was fabricated with 3 layers: the substrate (pyrex glass), the waveguide layer (sputtered with Corning 7059 glass) and sample layer having PVC sensing membrane and\\/or sample chamber. We

Haruyuki MINAMITANI; Kyungho KIM; Kunihiro MATSUMOTO

1998-01-01

191

Antibacterial activity against E. coli O157:H7, physical properties, and storage stability of novel carvacrol-containing edible tomato films.  

PubMed

Edible films containing plant antimicrobials are gaining importance as potential treatment to extend product shelf life and reduce risk of pathogen growth on contaminated food surfaces. The main objective of the present study was to evaluate the antimicrobial activities, storage stabilities, and physical-chemical-mechanica1 properties of novel edible films made from tomatoes containing carvacrol, the main constituent of oregano oil. The antimicrobial activities against E. coli O157:H7 and the stability of carvacrol were evaluated during the preparation and storage of tomato-based films made by 2 different casting methods, continuous casting and batch casting. Antimicrobial assays of tomato films indicated that optimum antimicrobial effects occurred with carvacrol levels of approximately 0.75% added to tomato purees before film preparation. HPLC analysis of the films indicated that the carvacrol concentrations and bactericidal effect of the films remained unchanged over the storage period of up to 98 d at 5 and 25 degrees C. Carvacrol addition to the tomato puree used to prepare the films increased water vapor permeability of tomato films. The continuous method for casting of the films appears more suitable for large-scale use than the batch method. This 1st report on tomato-based edible antimicrobial tomato films suggests that these films have the potential to prevent adverse effects of contaminated food and promote human health associated with the consumption of tomatoes. PMID:18803723

Du, W-X; Olsen, C W; Avena-Bustillos, R J; McHugh, T H; Levin, C E; Friedman, Mendel

2008-09-01

192

Dynamic daylight control system implementing thin cast arrays of polydimethylsiloxane-based millimeter-scale transparent louvers  

E-print Network

Dynamic daylight control system implementing thin cast arrays of polydimethylsiloxane: Daylight control system Dynamic window system Energy-efficiency Transparent louvers a b s t r a c in standard office buildings. The development of daylight control systems that maximize the penetration

Aizenberg, Joanna

193

Reduction of persistent photoconductivity in ZnO thin film transistor-based UV photodetector  

E-print Network

Reduction of persistent photoconductivity in ZnO thin film transistor-based UV photodetector Pavel 2012; accepted 3 July 2012; published online 19 July 2012) We report a ZnO-based thin film transistor UV photodetector with a back gate configuration. The thin-film transistor (TFT) aspect ratio W

Garfunkel, Eric

194

Measurement of Thermoelectric Properties of Amorphous Silicon Based Thin Films  

NASA Astrophysics Data System (ADS)

It is important to understand thermal transport behavior in materials for technological and fundamental physics applications. Many efforts have been made in the past for explaining thermal conduction in solids. It has been observed that thermal transport properties may change with reducing size of the sample, especially as sample size approaches the nanoscale regime. The deviation in these properties, mainly in thermal conductivity, may change the choice of the material for different applications such as thermoelectricity. Thermoelectric materials are a possible source of sustainable energy and can play an important role in the fight against the present energy crisis. Recently, better thermoelectric materials have become available in bulk form as compared to thin film form, with higher figure of merit (ZT = alpha2sigma T=k). ZT is a dimensionless quantity which is used to characterize the performance of thermoelectric materials in terms of the efficiency. Figure of merit (ZT) depends on three fundamental properties including thermal conductivity (k) which is challenging to measure for thin films. This is due to several reasons such as large or more than one background contribution and radiation heating above 100 K. Precise measurements of thermopower (alpha) also become critical for thin films in order to calculate ZT and the efficiency. For devices which rely on thin film technology it is important to have an accurate knowledge of how a material behaves as a thin film in a wide range of temperature. All three of these properties are a function of charge carrier concentration as well as of temperature. In my thesis, I will present novel experimental techniques and measurements of thermoelectric properties in amorphous based thin films over a wide range of temperature. Amorphous Si alloys are expected to have high efficiency for thermoelectric purposes because of their low thermal conductivity and the fact that we can control the charge carrier concentration for optimized thermopower(alpha) and electrical conductivity(sigma) by controlling the dopant concentration. Thermal properties of pure amorphous thin films are also potentially useful in micro- or nano fabrication techniques such as electrically insulating integrated devices. ii

Sultan, Rubina

195

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

196

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

197

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

198

Development of thin film diamond based integrated circuit technology  

NASA Astrophysics Data System (ADS)

In the portion of this project funded by BMDO/IST, we have been developing the elements of a diamond based semiconductor technology for high temperature applications. The approach is centered around incorporating a Schottky barrier contact and MOS field effect transistor using diamond films prepared by microwave plasma chemical vapor deposition (MPACVD). The experimental basis for this research is the successful fabrication in our laboratory of the world's first Schottky diodes with PACVD diamond base. These devices have characteristics similar to their counterparts fabricated using single crystal synthetic diamond prepared by high pressure methods. This has required a detailed understanding and control of the deposition process at it relates to the chemical purity and structural perfection of the resulting single crystal diamond films, in addition, detailed characterization of the films has allowed for meaningful preparation characterization electronic property relations. The ultimate goal of the proposed research is to fabricate transistors on single crystal heteroepitaxial diamond and to fabricate small scale integrated circuit operational at 400-500 C.

Badzian, Andrzej; Gildenblat, Gennady

1994-12-01

199

Large displacement vertical translational actuator based on piezoelectric thin films  

PubMed Central

A novel vertical translational microactuator based on thin-film piezoelectric actuation is presented, using a set of four compound bend-up/bend-down unimorphs to produce translational motion of a moving platform or stage. The actuation material is a chemical-solution deposited lead–zirconate–titanate (PZT) thin film. Prototype designs have shown as much as 120 ?m of static displacement, with 80–90 ?m displacements being typical, using four 920 ?m long by 70 ?m legs. Analytical models are presented that accurately describe nonlinear behavior in both static and dynamic operation of prototype stages when the dependence of piezoelectric coefficients on voltage is known. Resonance of the system is observed at a frequency of 200 Hz. The large displacement and high bandwidth of the actuators at low-voltage and low-power levels should make them useful to a variety of optical applications, including endoscopic microscopy. PMID:25506130

Qiu, Zhen; Pulskamp, Jeffrey S; Lin, Xianke; Rhee, Choong-Ho; Wang, Thomas; Polcawich, Ronald G; Oldham, Kenn

2014-01-01

200

Naphthacene Based Organic Thin Film Transistor With Rare Earth Oxide  

SciTech Connect

Naphthacene based organic thin film transistors (OTFTs) have been fabricated using La{sub 2}O{sub 3}, as the gate insulator. All the OTFTs have been fabricated by the process of thermal evaporation in vacuum on perfectly cleaned glass substrates with aluminium as source-drain and gate electrodes. The naphthacene film morphology on the glass substrate has been studied by XRD and found to be polycrystalline in nature. The field effect mobility, output resistance, amplification factor, transconductance and gain bandwidth product of the OTFTs have been calculated by using theoretical TFT model. The highest value of field effect mobility is found to be 0.07x10{sup -3} cm{sup 2}V{sup -1}s{sup -1} for the devices annealed in vacuum at 90 deg. C for 5 hours.

Konwar, K. [Department of Physics, Digboi College, Digboi-786171, Assam (India); Baishya, B. [Department of Physics, Dibrugarh University, Dibrugarh-786004, Assam (India)

2010-12-01

201

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

202

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

203

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

204

Cool Cast Facts  

MedlinePLUS

... Get Placed? First, the doctor or cast technician — tech for short (or another person who is trained ... some water on it. The doctor or cast tech wraps the plaster or fiberglass around the soft ...

205

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

Microsoft Academic Search

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

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

2006-01-01

206

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

207

Light-driven actuators based on polymer films  

NASA Astrophysics Data System (ADS)

We describe new light-driven actuators based on films of polymer polyvinylidene fluoride, known as PVDF. The actuators employ the photomechanic bending of the polymer film caused by low-power (10 mW and less) laser radiation. The photomechanic effect combines various physical mechanisms, such as thermal expansion, the converse piezoelectric mechanism, and the photovoltaic and pyroelectric mechanisms, while the mechanism of thermal expansion is dominant. The force applied by the actuators to external objects is measured with a torsion balance. It is proportional to the power of laser beam and could be as high as 10-4 N for a 50-µm film illuminated with a 10-mW laser beam. We demonstrate mechanical vibrations of a 1×7-mm strip actuator at a frequency of 0.3 kHz. As examples of possible applications, a photonic switch and an actuator with a closed-loop motion that could drive the inner workings of a conventional mechanical clock were demonstrated. The proposed actuators have a potential of being used as propulsion components of future light-driven micro/nano systems.

Sarkisov, Sergey S.; Curley, Michael J.; Huey, LaQuieta; Fields, Aisha B.; Sarkisov, Sergey S., II; Adamovsky, Grigory

2006-03-01

208

36 CFR 1237.30 - How do agencies manage records on nitrocellulose-base and cellulose-acetate base film?  

Code of Federal Regulations, 2011 CFR

...Agencies must handle nitrocellulose-base film (used in the manufacture of sheet film, 35 mm motion pictures, aerial and still photography into the 1950s) as specified below: (1) Remove nitrocellulose film materials (e.g., 35mm motion picture...

2011-07-01

209

36 CFR 1237.30 - How do agencies manage records on nitrocellulose-base and cellulose-acetate base film?  

...Agencies must handle nitrocellulose-base film (used in the manufacture of sheet film, 35 mm motion pictures, aerial and still photography into the 1950s) as specified below: (1) Remove nitrocellulose film materials (e.g., 35mm motion picture...

2014-07-01

210

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

211

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

212

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

213

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.

Perkins School for the Blind

2012-06-26

214

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

215

Effects of Fluorine and BaO on the Crystallization Behavior of Lime-Alumina-Based Mold Flux for Casting High-Al Steels  

NASA Astrophysics Data System (ADS)

With the development of advanced high-strength steel, the slag/steel reaction problems introduced by the addition of aluminum into steel become a challenge for the continuous casting process. An investigation aims to improve the crystallization property of lime-alumina-based mold flux for casting high Al-bearing steels which was carried out through the study of effects of fluorine and BaO on the crystallization behaviors of the mold flux. The single/double hot thermocouple technique and SEM, EDS were employed in the study. The results indicated that the decrease of fluorine content would promote the crystallization behaviors in the lime-alumina-based system which is different to that in the conventional lime-silica-based system, while BaO substituted for CaO can inhibit the crystallization of the lime-alumina-based mold flux. Moreover, the crystallization behavior of mold flux under simulated thermal gradient was in well accordance with TTT results, including the crystallization process and three-layered (liquid, crystalline, glassy) distribution of mold flux.

Lu, Boxun; Wang, Wanlin

2015-01-01

216

Effect of edible wheat gluten-based films and coatings on refrigerated strawberry ( Fragaria ananassa) quality  

Microsoft Academic Search

Edible coatings and films can provide an alternative for extending the postharvest life of fresh fruits and vegetables. The effect of different wheat gluten-based coatings and films on refrigerated strawberry quality and shelf life was studied. Coatings were formed directly on the surface of the fruit and films were previously formed (on Teflon surfaces) and then used to pack fruit.

Patrícia S. Tanada-Palmu; Carlos R. F. Grosso

2005-01-01

217

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

218

Cooling Performance and Structural Reliability of a Modified Corrugated-insert Air-cooled Turbine Blade with an Integrally Cast Shell and Base  

NASA Technical Reports Server (NTRS)

A modified corrugated-insert blade with integrally cast shell and base was developed. This blade was as light as a conventional fabricated corrugated-insert blade. Of four test blades operated in a full-scale turbojet engine, one failed after about 15 hours operation at an inlet gas temperature of 1670 degrees F, a coolant-flow ratio of 0.0064, and a 1/3-span centrifugal stress of approximately 28,000 psi. Three other test blades ran for approximately 16, 31, and 36 hours without failure at similar conditions.

Freche, John C; Schum, Eugene F

1957-01-01

219

Solution processing of conjugated polymers: the effects of polymer solubility on the morphology and electronic properties of semiconducting polymer films  

Microsoft Academic Search

It is becoming increasingly clear that the electronic properties of conjugated polymers are controlled by the way the films are cast: changing the solvent, spin speed or concentration changes the film morphology and thus the performance of devices based on these materials. In this paper, we show that the way a conjugated polymer is dissolved into solution also affects the

Thuc-Quyen Nguyen; Rena Y. Yee; Benjamin J. Schwartz

2001-01-01

220

Film  

Microsoft Academic Search

\\u000a The rigorous and systematized application of phenomenology to the study of film has been a comparatively late development\\u000a in film studies. Vivian Sobchack’s ground breaking book, The Address of the Eye: A Phenomenology of Film Experience (1992), has brought to light the relevance of maurice merleau-ponty’s existential phenomenology to major aesthetic and theoretical aspects of the film experience. In so

Elena del Río

221

Vitreous tin oxide-based thin film electrodes for Li-ion micro-batteries  

Microsoft Academic Search

Sputter deposited thin films from a Sn\\/(SnO)(B2O3)0.3(P2O5)0.2 composite target are investigated as an alternative to the lithium metal anode for lithium-ion micro-batteries. Experimental conditions related to the manufacturing of the target and elaboration of the vitreous thin films are described. Chemical and physical properties of the thin layer films are presented. Regarding the electrochemical behavior, vitreous tin oxide-based thin films

C Branci; N Benjelloun; J Sarradin; M Ribes

2000-01-01

222

The effects of Cr, Co, Al, Mo and Ta on the cyclic oxidation behavior of a prototype cast Ni-base superalloy based on a 2 sup 5 composite statistically designed experiment  

Microsoft Academic Search

A series of cast Ni-base γ\\/γⲠSuperalloys with nominally fixed levels of 1 w\\/o Ti, 2w\\/o W, 1 w\\/o Nb, .10 w\\/o Zr, .12 w\\/o C and .01B w\\/o were systematically varied at selected levels of Co, Cr, Mo, Ta, and Al. The alloy compositions were based on a full 2⁵-fractional statistical design supplemented by 5 x 2 star point

Barrett

2008-01-01

223

PVDF-PZT nanocomposite film based self-charging power cell  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

224

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

225

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

226

Paper-based transparent flexible thin film supercapacitors  

NASA Astrophysics Data System (ADS)

Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm).Paper-based transparent flexible thin film supercapacitors were fabricated using CNF-[RGO]n hybrid paper as an electrode material and charge collector. Owing to the self-anti-stacking of distorted RGO nanosheets and internal electrolyte nanoscale-reservoirs, the device exhibited good electrochemical performance (about 1.73 mF cm-2), and a transmittance of about 56% (at 550 nm). Electronic supplementary information (ESI) available: Experimental, TEM image, IR spectra, and XRD spectra of cellulose nanofibers, TEM image, and XRD spectra of RGO, graphite, GO nanosheets, CNF paper, and CNF-[RGO]20 hybrid paper, high-resolution C1s spectra of GO, Raman spectra of GO nanosheets, cross-sectional FESEM image of CNF-[RGO]20 hybrid paper and stress-strain curve of T-SC-20. See DOI: 10.1039/c3nr00674c

Gao, Kezheng; Shao, Ziqiang; Wu, Xue; Wang, Xi; Zhang, Yunhua; Wang, Wenjun; Wang, Feijun

2013-05-01

227

Gating of Permanent Molds for Aluminum Casting  

SciTech Connect

This report summarizes a two-year project, DE-FC07-011D13983 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 to 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. Equipment and procedure for real time X-Ray radiography of molten aluminum flow into permanent molds have been developed. Other studies have been conducted using water flow and behavior of liquid aluminum in sand mold using real time photography. This investigation utilizes graphite molds transparent to X-Rays making it possible to observe the flow pattern through a number of vertically oriented grating systems. These have included systems that are choked at the base of a rounded vertical sprue and vertical gating systems with a variety of different ingates into the bottom of a mold cavity. These systems have also been changed to include gating systems with vertical and horizontal gate configurations. Several conclusions can be derived from this study. A sprue-well, as designed in these experiments, does not eliminate the vena contracta. Because of the swirling at the sprue-base, the circulating metal begins to push the entering metal stream toward the open runner mitigating the intended effect of the sprue-well. Improved designs of sprue-wells should be evaluated. In order for a runner extension to operate efficiently, it must have a small squared cross-section. If it is tapered, the first metal to enter the first metal to enter the system is not effectively trapped. If the cross section is large, there is less turbulence when the aluminum enters the mold cavity in comparison to the smaller cross sectioned, squared runner. However, a large runner reduces yield. In bottom-feeding gating systems, a filter can significantly improve the filling of the casting. The filter helps to slow the metal flow rate enough to reduce jetting into the mold cavity. In top feeding gating systems, a filter can initially slow the metal flow rate, but because the metal drops after passing the filter, high velocities are achieved during free fall when a filter is in place. Side feeding gating systems provide less turbulent flow into the mold cavity. The flow is comparable to a bottom-feeding gating system with a filter. Using properly designed side-gating system instead of a bottom-feeding system with a filter can potentially save the cost of the filter. Rough coatings promote better fill than smooth coatings. This conclusion seems at first counter intuitive. One tends to assume a rough coating creates more friction resistance to the flow of molten metal. In actuality the molten aluminum stream flows inside an oxide film envelope. When this film rests on top of the ridges of a rough coating the microscopic air pockets between the coating and the oxide film provide more thermal insulation than in a smooth coating. This insulation promotes longer feeding distances in the mold as demonstrated in the experiments. Much of this work is applicable to vertically parted sand molds as well, although the heat transfer conditions do vary from a metal mold generally used in permanent molding of aluminum. The flow measurements were conducted using graphite molds and real time X-Ray radiography recorded at a rate of 30 images per second through those molds. The facilities at Arrow Aluminum Foundry were used in the study. The resu

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

2004-01-01

228

Design of novel miconazole nitrate transdermal films based on Eudragit RS100 and HPMC hybrids: preparation, physical characterization, in vitro and ex vivo studies.  

PubMed

Abstract The objective of this study was to formulate and evaluate transdermal films containing miconazole nitrate (MN), a poorly water-soluble imidazole antifungal agent, with a view to enhancing its delivery across intact skin. Transdermal films of MN were formulated by solvent casting technique using admixtures of film-forming polymers - Eudragit RS100 and hydroxypropylmethylcellulose (HPMC) (2:8, 4:6, 5:5, 6:4 and 8:2) with polyethylene glycol 8000 (plasticizer and permeation enhancer) and Tween 80 (mobile surfactant). The films were evaluated for weight uniformity, folding endurance, thickness, moisture loss and uptake, bioadhesive strength, drug content, skin irritation on rabbits and time-resolved stability. The ex vivo release of MN from the films was carried out using a modified Franz diffusion apparatus while the microbiological evaluation was conducted using a clinical isolate of Candida albicans. Overall results indicate that films made with two portions of Eudragit RS100 and eight portions of HPMC (batch T-1) had the least weight variation (57.33?±?0.27?mg), folding endurance (307.90?±?4.17), moisture uptake (1.37?±?0.28%) and thickness (145.9?±?2.08?µm), but highest drug content (97.50?±?2.43%) and bioadhesive strength (81.40?±?2.03?dyne/cm(2)), best bioactivity and in vitro skin permeation through rat skin with highest permeation flux (5.161?µg/cm(2)?h) and permeation coefficient (1.032?×?10(-6?)cm/h) compared to all other formulations. This study has established that transdermal films based on 2:8 admixtures of Eudragit RS100 and HPMC could offer a promising approach for the treatment of skin infections caused by MN-susceptible fungi. PMID:24455998

Ofokansi, Kenneth C; Kenechukwu, Franklin C; Ogwu, Nkechi N

2014-01-23

229

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

230

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

231

Thin film thermocouples for internal combustion engines  

NASA Astrophysics Data System (ADS)

Procedures for fabricating thin film thermocouples on internal combustion engine hardware are examined experimentally. The techniques for growing a thermal oxide on cast iron, ferritic steel, and austenitic steel samples, representing engine hardware, with an FeCrAlY coating using an Al2O3 insulation layer are described. The adhesion, stability, and electrical performance of the aluminum oxide coating and platinum plus platinum-rhodium thermocouple films are analyzed. It is observed that thin film sputtered thermocouples of platinum plus platinum-rhodium can be fabricated on iron-base alloys using Al2O3 insulation formed thermally on FeCrAlY and by reactive sputtering.

Kreider, Kenneth G.

1986-12-01

232

Bamboo (Neosinocalamus affinis)-based thin film, a novel biomass material with high performances.  

PubMed

Exploration of biomass based materials to replace conventional petroleum based ones has been a trend in recent decades. In this work, bamboo (Neosinocalamus affinis) with abundant resources was used for the first time to prepare films in the presence of cellulose. The effects of weight ratio of bamboo/cellulose on the appearances and properties of the films were investigated. It was confirmed there existed strong interactions between bamboo and cellulose, which were favorable to formation of homogeneous structure of blend films. Particularly, the presence of bamboo could improve the surface hydrophobicity, water resistance and thermal stability of blend films, and the films possessed an excellent oxygen barrier property, compared with generally used commercial packaging films. The bamboo biomass, therefore, is successfully used to create a new film material with a good application prospect in the fields of packaging, coating, and food industry. PMID:25563957

Song, Fei; Xu, Chen; Bao, Wen-Yi; Wang, Xiu-Li; Wang, Yu-Zhong

2015-03-30

233

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

234

Pb-based ferroelectric thin film actuator for optical applications  

Microsoft Academic Search

Novel PZT thin film actuators for optical applications were proposed. Key issues for realizing the actuators such as PZT thin\\u000a film processes, mechanical properties evaluation of thin films, and design for laminated structure were described. [1 1 1]-oriented\\u000a PZT films were obtained by anneal\\/non-anneal sputtering process. Also for PZT dry etching, it was made clear low pressure\\u000a and low temperature

M. Sakata; S. Wakabayashi; M. Ikeda; H. Goto; M. Takeuchi; T. Yada

1995-01-01

235

Property evaluations of dry-cast reconstituted bacterial cellulose/tamarind xyloglucan biocomposites.  

PubMed

We describe the mechanical defibrillation of bacterial cellulose (BC) followed by the dry-cast generation of reconstituted BC films (RBC). Xyloglucan (XGT), extracted from tamarind seeds, was incorporated into the defibrillated cellulose at various compositions, and new films were created using the same process. Microscopy and contact angle analyses of films revealed an increase in the microfibre adhesion, a reduced polydispersity in the diameters of the microfibrils and increased hydrophobic behaviour as a function of %XGT. X-ray diffraction analysis revealed changes to the crystallographic planes of the RBC and the biocomposite films with preferential orientation along the (110) plane. Compared with BC, RBC/XGT biocomposite with 10% XGT exhibited improvement in its thermal properties and in Young's modulus. These results indicated a reorganisation of the microfibres with mechanical treatment, which when combined with hydrocolloids, can create cellulose-based materials that could be applied as scaffolding for tissue engineering and drug release. PMID:23465913

de Souza, Clayton F; Lucyszyn, Neoli; Woehl, Marco A; Riegel-Vidotti, Izabel C; Borsali, Redouane; Sierakowski, Maria Rita

2013-03-01

236

The Role of Residual Casting Solvent in Determining the Lithographic and Dissolution Behavior of Poly(methyl Methacrylate), a Positive Electron Beam Resist.  

NASA Astrophysics Data System (ADS)

The effect of the pre-exposure bake and the choice of casting solvent on the sensitivity and contrast of PMMA has been documented to an extent not previously reported in the literature. PMMA films were spin cast onto clean silicon substrates from chlorobenzene and tri-chloroethylene solutions. The temperature of the pre-bake was varied over the range of 59^circ to 170^circC using a convection oven with pre-bake times ranging from 30 to 90 minutes. At the end of the designated bake time, the films were removed from the oven and allowed to cool in a temperature and humidity controlled environment. They were promptly exposed to a 15 KeV electron beam, then developed, with mild agitation, in a 1:1 mixture of MIBK and IPA at 22.5^ circC. Film thickness profiles were determined with an alpha-step profilometer. Films baked at temperatures below T_{rm glass} (the temperature which marks the onset of long-range, coordinated molecular motion), exhibited improved sensitivity and poorer contrast when compared to those baked above T_{rm glass }. Unique to this work is the finding that the lithographic performance depends on the choice of casting solvent, even at pre-bake temperatures significantly above T_{rm glass}. The relative concentrations of the casting solvents remaining in the baked films was determined from UV absorption spectra. The dissolution rates of exposed films were also measured and compared to the fragmented molecular weight model of development. Energy depositions were calculated from the empirical model of Everhart and Hoff. Cross-correlation of these results indicate that the pre-bake temperature more strongly correlates with the observed improvement in sensitivity than the presence of residual casting solvent. Residual casting solvent changes the density of the film, thus changing the energy deposition and dissolution behavior. Calculations based on the aforementioned models indicate that the observed lithographic and dissolution behavior can not be accounted for by this change in density. Arguments are presented to support the conclusion that the observed behavior is associated with film morphology. Comparison of results from films cast from TCE and chlorobenzene and baked above T_{rm glass} further support this conclusion.

Criss, Robert Randolph, Jr.

237

Polyhydroxyalkanoate-based natural synthetic hybrid copolymer films: A small-angle neutron scattering study  

NASA Astrophysics Data System (ADS)

Polyhydroxyalkanoates have attracted attention as biodegradable alternatives to conventional thermoplastics and as biomaterials. Through modification of their biosynthesis using Pseudomonas oleovorans, we have manipulated the material properties of these biopolyesters and produced a natural-synthetic hybrid copolymer of polyhydroxyoctanoate- block-diethylene glycol (PHO- b-DEG). A mixture of PHO and PHO-DEG were solvent cast from analytical grade chloroform and analysed using small-angle neutron scattering. A scattering pattern, easily distinguished above the background, was displayed by the films with a diffraction ring at q?0.12 Å -1. This narrow ring of intensity is suggestive of a highly ordered system. Analysis of the diffraction pattern supported this concept and showed a d-spacing of approximately 50 Å. In addition, conformation of the hybrid polymer chains can be manipulated to support their self-assembly into ordered microporous films.

Foster, L. John R.; Knott, Robert; Sanguanchaipaiwong, Vorapat; Holden, Peter J.

2006-11-01

238

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

239

Photosensitive properties of composite films based on copper chloride in polymer matrix  

NASA Astrophysics Data System (ADS)

The composite films based on PMMA and CuCl2 were prepared. Transmission spectra of the films before and after illumination by different laser lines (405, 448, 456 nm) were measured. The reversible character of the composite photosensitivity was fixed. The phenomenon of direct surface relief formation after laser beam illumination of composite films was described. The holographic gratings were recorded by different exposure (200 - 500 J/cm2) in the films with different concentration (8 and 20 wt. %) of copper salt. The film sensitivity dependence on polymer molecular weight was studied. Surface relief of the gratings was measured by AFM.

Gerbreders, A.; Bulanovs, A.; Sledevskis, E.; Gerbreders, V.; Teteris, J.

2013-12-01

240

Dielectric functions of DNA base films from near-infrared to ultra-violet  

Microsoft Academic Search

This work is reporting the dielectric functions of DNA base films, i.e. guanine, adenine, cytosine, and thymine in the energy range from near-infrared to ultra-violet. Spectroscopic ellipsometry using synchrotron radiation was employed in situ on DNA base films grown on hydrogen terminated Si(111) surfaces under ultra-high vacuum conditions. The optical response of adenine and guanine films is described by a

S. D. Silaghi; M. Friedrich; C. Cobet; N. Esser; W. Braun; D. R. T. Zahn

2005-01-01

241

Mechanical, water vapor barrier and thermal properties of gelatin based edible films  

Microsoft Academic Search

Edible films are thin materials based on a biopolymer. The objectives of this work were to determine the water vapor permeability and the mechanical and thermal properties of edible films based on bovine hide and pigskin gelatins. These films were prepared with 1g of gelatin\\/100ml of water; 15–65g sorbitol\\/100g gelatin; and at natural pH. The samples were conditioned at 58%

P. J. A. Sobral; F. C. Menegalli; M. D. Hubinger; M. A. Roques

2001-01-01

242

Development, processing, and characterization of cellulose nanocrystal neat films  

NASA Astrophysics Data System (ADS)

Methods for processing quality cellulose nanocrystal (CNC) suspensions using sulfuric acid hydrolysis of microcrystalline cellulose were developed and optimized. The resulting suspensions were used to develop shear-based methods for casting neat CNC films. These methods were used to produce oriented CNC films from the Purdue-made (long crystals, CNC-L) and FPL-made (short crystals, CNC-S) CNC suspensions. Increased casting shear rate increased the degree of CNC orientation as quantified by Hermans order parameter, S. The highest shear rate (100·s-1) produced maximum orientation, with resulting Hermans order parameter of S = 0.36 in the CNC-S film. Elastic modulus, ultimate tensile strength, and elongation at failure were measured with respect to film casting direction and CNC orientation. Elastic modulus in CNC films scaled directly with orientation and reached a maximum average of 23 GPa. Tensile strength did not scale with orientation, but was strongly linked to CNC length, where a maximum strength of 196 MPa was measured. In addition to CNC length and shear rate, suspension pH and heat treatment also affected film properties. As the pH of casting suspensions was increased from ˜3 to ˜7, orientation retention in films was increased, and a new maximum modulus of 30 GPa was observed at S = 0.53 for the CNC-S film. The mechanical properties of all neutral pH films were further enhanced through heat treatment, in which a 1-4 GPa increase in elastic modulus was observed, as well as a 40-80 MPa increase in tensile strength for all axially oriented films.

Reising, Alexander B.

243

Amorphous photochromic films based on spirophenanthro-oxazine  

NASA Astrophysics Data System (ADS)

Two regimes of vacuum deposition of 1',3',3'- trimethylspiro[indoline-2',3-2H-1-phenanthro-[9,10- b][1,4]-oxazine] (SPO) leading to the formation of amorphous films showing photochromic properties were determined. It was established that at room temperature a thermal decoloration of these films does not occur. It was suggested that the complex absorption spectrum of colored film and the character of its change at a film storage on natural light are due to the formation of different SPO photoinduced form stereoisomers. The long-duration storage of the amorphous film leads to its crystallization with following loss of photochromic properties.

Sychev, I. Y.; Khamchukov, Yu. D.; Marevtsev, Victor S.; Zaichenko, N. L.; Anishenko, E. V.

1998-01-01

244

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

245

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

246

Tungsten oxide proton conducting films for low-voltage transparent oxide-based thin-film transistors  

SciTech Connect

Tungsten oxide (WO{sub x}) electrolyte films deposited by reactive magnetron sputtering showed a high room temperature proton conductivity of 1.38 Multiplication-Sign 10{sup -4} S/cm with a relative humidity of 60%. Low-voltage transparent W-doped indium-zinc-oxide thin-film transistors gated by WO{sub x}-based electrolytes were self-assembled on glass substrates by one mask diffraction method. Enhancement mode operation with a large current on/off ratio of 4.7 Multiplication-Sign 10{sup 6}, a low subthreshold swing of 108 mV/decade, and a high field-effect mobility 42.6 cm{sup 2}/V s was realized. Our results demonstrated that WO{sub x}-based proton conducting films were promising gate dielectric candidates for portable low-voltage oxide-based devices.

Zhang, Hongliang; Wan, Qing; Wan, Changjin; Wu, Guodong; Zhu, Liqiang [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)] [Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China)

2013-02-04

247

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

248

A microwave phase shifter based on a planar ferrite-ferroelectric thin-film structure  

NASA Astrophysics Data System (ADS)

Microwave phase shifters employing slot transmission lines based on thin ferroelectric films of barium strontium titanate and thin single-crystalline films of yttrium iron garnet ferrite have been experimentally studied for the first time. The phase shifters admit double electronic control based upon the phenomenon of hybridization of the electromagnetic wave propagating in a slot delay line on the ferroelectric film and the spin wave propagating in the ferrite film. At a bias voltage of 150 V applied to electrodes of the slot lines with 50- and 150-?m-wide slots, the phase shift amounted to 53° and 26°, respectively.

Nikitin, A. A.; Ustinov, A. B.; Semenov, A. A.; Kalinikos, B. A.

2014-04-01

249

Journal of Membrane Science 205 (2002) 1121 Macrovoid pore formation in dry-cast cellulose acetate  

E-print Network

Journal of Membrane Science 205 (2002) 11­21 Macrovoid pore formation in dry-cast cellulose acetate of macrovoid (MV) pores formed during the dry-casting of cellulose acetate (CA)/acetone/water casting solutions were cast in low-gravity (low-g) (KC-135) and normal-gravity (1-g) (ground-based control) from CA

Shvartsman, Stanislav "Stas"

250

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

251

Nanostructured biocomposite films of high toughness based on native chitin nanofibers and chitosan.  

PubMed

Chitosan is widely used in films for packaging applications. Chitosan reinforcement by stiff particles or fibers is usually obtained at the expense of lowered ductility and toughness. Here, chitosan film reinforcement by a new type of native chitin nanofibers is reported. Films are prepared by casting from colloidal suspensions of chitin in dissolved chitosan. The nanocomposite films are chitin nanofiber networks in chitosan matrix. Characterization is carried out by dynamic light scattering, quartz crystal microbalance, field emission scanning electron microscopy, tensile tests and dynamic mechanical analysis. The polymer matrix nanocomposites were produced in volume fractions of 8, 22, and 56% chitin nanofibers. Favorable chitin-chitosan synergy for colloidal dispersion is demonstrated. Also, lowered moisture sorption is observed for the composites, probably due to the favorable chitin-chitosan interface. The highest toughness (area under stress-strain curve) was observed at 8 vol% chitin content. The toughening mechanisms and the need for well-dispersed chitin nanofibers is discussed. Finally, desired structural characteristics of ductile chitin biocomposites are discussed. PMID:25478558

Mushi, Ngesa E; Utsel, Simon; Berglund, Lars A

2014-01-01

252

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

253

Evaluation of the Influence of Formulation and Process Variables on Mechanical Properties of Oral Mucoadhesive Films Using Multivariate Data Analysis  

PubMed Central

Oral mucosa is an attractive region for the local and systemic application of many drugs. Oral mucoadhesive films are preferred for their prolonged time of residence, the improved bioavailability of the drug they contain, their painless application, their protection against lesions, and their nonirritating properties. This work was focused on preparation of nonmedicated carmellose-based films using both solvent casting and impregnation methods, respectively. Moreover, a modern approach to evaluation of mucoadhesive films applying analysis of texture and subsequent multivariate data analysis was used. In this experiment, puncture strength strongly correlated with tensile strength and could be used to obtain necessary information about the mechanical film characteristics in films prepared using both methods. Puncture work and tensile work were not correlated in films prepared using the solvent casting method, as increasing the amount of glycerol led to an increase in the puncture work in thinner films. All measured texture parameters in films prepared by impregnation were significantly smaller compared to films prepared by solvent casting. Moreover, a relationship between the amount of glycerol and film thickness was observed, and a greater recalculated tensile/puncture strength was needed for an increased thickness in films prepared by impregnation. PMID:25136560

Landová, Hana; Gajdziok, Jan; Doležel, Petr; Muselík, Jan; Dvo?á?ková, Kate?ina; Jekl, Vladimír; Hauptman, Karel

2014-01-01

254

Reduced graphene oxide based silver sulfide hybrid films formed at a liquid/liquid interface  

SciTech Connect

Free-standing, ultra-thin films of silver sulfide and reduced graphene oxide (RGO) based silver sulfide hybrids are prepared at a liquid/liquid interface employing in situ chemical reaction strategy. Ag{sub 2}S and RGO?Ag{sub 2}S hybrid films are characterized by various techniques such as UV-visible and photo luminescence spectroscopy, X-ray diffraction and scanning electron microscopy. The morphology of hybrid films consists of Ag{sub 2}S nanocrystals on RGO surface while Ag{sub 2}S films contains branched network of dendritic structures. RGO?Ag{sub 2}S exhibit interesting optical and electrical properties. The hybrid films absorb in the region 500–650 nm and show emission in the red region. A higher conductance is observed for the hybrid films arising from the RGO component. This simple low cost method can be extended to prepare other RGO based metal sulfides.

Bramhaiah, K., E-mail: jsneena@csmr.res.in; John, Neena S., E-mail: jsneena@csmr.res.in [Centre for Soft Matter Research, P.B. No.1329, Jalahalli, Bangalore-560013 (India)

2014-04-24

255

The influence of high thermal gradient casting, hot isostatic pressing and alternate heat treatment on the structure and properties of a single crystal nickel base superalloy  

NASA Technical Reports Server (NTRS)

A development program has been conducted to improve the cyclic properties of the PWA 1480 single-crystal superalloy by reducing or entirely eliminating casting porosity at fatigue-initiation sites, through the use of improved casting process parameters and HIPing; potential mechanical property improvements in a high-pressure hydrogen environment were also sought in alternatives to the standard coating and heat-treatment cycle. High thermal gradient casting was found to yield a reduction in overall casting porosity density and pore sizes. The most dramatic mechanical property improvement resulted from HIPing.

Fritzemeier, L. G.

1988-01-01

256

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

257

Spin-Cast and Patterned Organophosphonate Self-Assembled Monolayer Dielectrics on Metal-Oxide-Activated Si  

SciTech Connect

An efficient process is developed for modifying Si with self-assembled monolayers (SAMs) through in situ metal oxide surface activation and microcontact printing or spin-coating of phosphonic-acid-based molecules. The utility of this process is demonstrated by fabricating self-organized and solution-processed low-voltage organic thin-film transistors enabled by patterned and spin-cast phosphonate SAM/metal oxide hybrid dielectrics.

O Acton; D Hutchins; L Arnadottir; T Weidner; N Cernetic; G Ting; T Kim; D Castner; H Ma; A Jen

2011-12-31

258

Junctionless Flexible Oxide-Based Thin-Film Transistors on Paper Substrates  

Microsoft Academic Search

Junctionless flexible oxide-based electric-double-layer thin-film transistors (TFTs) are fabricated on paper substrates at room temperature. Channel and source\\/drain electrodes are realized by an indium–tin–oxide (ITO) film without any source\\/drain junction. Effective field-effect modulation of drain current can be obtained when the thickness of the top ITO film is decreased to 20 nm. These junctionless paper TFTs show a good device

Jie Jiang; Jia Sun; Wei Dou; Qing Wan

2012-01-01

259

Evaluation of variational principle based model for LDPE large scale film blowing process  

NASA Astrophysics Data System (ADS)

In this work, variational principle based film blowing model combined with Pearson and Petrie formulation, considering non-isothermal processing conditions and novel generalized Newtonian model allowing to capture steady shear and uniaxial extensional viscosities has been validated by using experimentally determined bubble shape and velocity profile for LDPE sample on large scale film blowing line. It has been revealed that the minute change in the flow activation energy can significantly influence the film stretching level.

Kolarik, Roman; Zatloukal, Martin

2013-04-01

260

TiNi-based thin films in MEMS applications: a review  

Microsoft Academic Search

TiNi thin films have attracted much attention in recent years as intelligent and functional materials because of their unique properties. TiNi thin film based micro-actuators will become the actuator of choice in many aspects in the rapidly growing field of micro-electro-mechanical systems (MEMSs). In this review paper, some critical issues and problems in the development of TiNi thin films are

Yongqing Fu; Hejun Du; Weimin Huanga; Sam Zhang; Min Hu

2004-01-01

261

A comparison of chemical sensors based on the different ordered inverse opal films  

Microsoft Academic Search

The three different inverse opal films including polystyrene (PS), silicon dioxide (SiO2) and titanium dioxide (TiO2) inverse opal have been fabricated by the self-assembly colloidal crystal template technique. Based on the Bragg's law, these inverse opal films were used as chemical sensors chips to detect the different concentration of ethanol solutions. The optical sensing properties of three inverse opal films

Jianlin Li; Tiesong Zheng

2008-01-01

262

Ethanol gas sensors based on copper phthalocyanine thin-film transistors  

Microsoft Academic Search

A bottom contact copper phthalocyanine (CuPc) based organic thin film transistor (OTFT) was fabricated in this paper. CuPc thin film acting both as gas sensing layer and the active layer was formed by vacuum evaporation and was characterized by scanning electron microscope(SEM). The results show that the film is highly ordered and has a polycrystalline morphology. The current-voltage characteristics of

Xian Li; Ya-Dong Jiang; Guang-Zhong Xie; Xiao-Song Du; Hui-Ling Tai; Jian-Fei Yan; Song-Qi Fu

2010-01-01

263

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

264

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

265

Effect of adhesive primers on bonding strength of heat cure denture base resin to cast titanium and cobalt-chromium alloy  

PubMed Central

STATEMENT OF PROBLEM The poor chemical bonding of a denture base resin to cast titanium framework often introduces adhesive failure and increases microleakage. PURPOSE This study evaluated the shear bond strengths of a heat cure denture base resin to commercially pure titanium, Ti-6Al-4V alloy and a cobalt-chromium alloy using two adhesive primers. MATERIAL AND METHODS Disks of commercially pure titanium, Ti-6Al-4V alloy and a cobalt-chromium alloy were cast. Specimens without the primer were also prepared and used as the controls. The shear bond strengths were measured on a screw-driven universal testing machine. RESULTS The primers significantly (P < .05) improved the shear bond strengths of the heat cure resin to all metals. However, the specimens primed with the Alloy primer® (MDP monomer) showed higher bond strength than those primed with the MR bond® (MAC-10 monomer) on titanium. Only adhesive failure was observed at the metal-resin interface in the non-primed specimens, while the primed specimens showed mixed failure of adhesive and cohesive failure. CONCLUSIONS The use of appropriate adhesive metal primers makes it possible not only to eliminate the need for surface preparation of the metal framework before applying the heat cure resins, but also reduce the need for retentive devices on the metal substructure. In particular, the Alloy primer®, which contains the phosphoric acid monomer, MDP, might be clinically more acceptable for bonding a heat cure resin to titanium than a MR bond®, which contains the carboxylic acid monomer, MAC-10. PMID:21165254

Kim, Su-Sung; Yang, Hong-So; Park, Sang-Won; Lim, Hyun-Pil

2009-01-01

266

Multielectrocatalysis by Layer-by-Layer Films Based on Pararosaniline and Vanadium-Substituted Phosphomolybdate.  

PubMed

Hybrid multilayer films based on the two molecular species pararosaniline (PR) and Keggin-type polyoxometalate K5[PMo11VO40)] (PMo11V) were prepared on different substrates using the electrostatic layer-by-layer (LbL) self-assembly method. The film buildup, monitored by electronic spectroscopy, showed a regular stepwise growth, and X-ray photoelectron spectroscopy data confirmed the presence of both molecular components within the LbL films. Scanning electron microscopy images revealed a completely covered surface with a nonuniform distribution of film components, and atomic force microscopy images confirmed a rough surface. The film electrochemical responses and permeability were studied by cyclic voltammetry. Films revealed three Mo-based redox processes (Mo(VI) ? Mo(V)) and one V-based redox process (V(V) ? V(IV)) in the potential range between 0.8 and -0.4 V vs Ag/AgCl. Studies with the redox probes [Fe(CN)6](3-/4-) and [Ru(NH3)6](3+/2+) showed that the films maintain the permeability even after six bilayers. Furthermore, the {PR/PMo11V}n multilayer films exhibit excellent Mo-based electrocatalytic activity toward reduction of iodate and V-based electrocatalytic activity toward ascorbic acid oxidation, thus acting as a versatile multielectrocatalyst. PMID:25603457

Fernandes, Diana M; Teixeira, Alexandra; Freire, Cristina

2015-02-10

267

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

268

Neutron radiography inspection of investment castings.  

PubMed

Investment casting, also known as the lost wax process, is a manufacturing method employed to produce near net shape metal articles. Traditionally, investment casting has been used to produce structural titanium castings for aero-engine applications with wall thickness less than 1 in (2.54 cm). Recently, airframe manufacturers have been exploring the use of titanium investment casting to replace components traditionally produced from forgings. Use of titanium investment castings for these applications reduces weight, cost, lead time, and part count. Recently, the investment casting process has been selected to produce fracture critical structural titanium airframe components. These airframe components have pushed the traditional inspection techniques to their physical limits due to cross sections on the order of 3 in (7.6 cm). To overcome these inspection limitations, a process incorporating neutron radiography (n-ray) has been developed. In this process, the facecoat of the investment casting mold material contains a cocalcined mixture of yttrium oxide and gadolinium oxide. The presence of the gadolinium oxide, allows for neutron radiographic imaging (and eventual removal and repair) of mold facecoat inclusions that remain within these thick cross sectional castings. Probability of detection (POD) studies have shown a 3 x improvement of detecting a 0.050 x 0.007 in2 (1.270 x 0.178 mm2) inclusion of this cocalcined material using n-ray techniques when compared to the POD using traditional X-ray techniques. Further, it has been shown that this n-ray compatible mold facecoat material produces titanium castings of equal metallurgical quality when compared to the traditional materials. Since investment castings can be very large and heavy, the neutron radiography facilities at the University of California, Davis McClellan Nuclear Radiation Center (UCD/MNRC) were used to develop the inspection techniques. The UCD/MNRC has very unique facilities that can handle large parts up to 39 ft (12 m) in length and 13 ft (4 m) high weighing up to 5000 lbs (2300 kg). These handling systems are robotically driven. The neutron radiographic system consists of a highly thermalized neutron beam. The neutron beam has an intensity of 5.6 x 10(6) n/cm2 s, with a L/D = 200 at a power of 2 MW. A divergent beam collimator is used which provides a beam of approximately 22 in (56 cm) in diameter at the film plane. A vacuum cassette with a gadolinium vapor deposited screen is used to collect the image. Exposure times can be as short as 3 min, or up to 30 min. PMID:15246417

Richards, W J; Barrett, J R; Springgate, M E; Shields, K C

2004-10-01

269

Casting Alloys: Side-Effects  

Microsoft Academic Search

Side-effects from dental materials are a minor problem, but should be recognized. In recent questionnaire surveys about side-effects, the incidence was estimated to be 1:300 in periodontics and 1:2600 in pedodontics. None of these reactions was related to dental casting alloys. In prosthodontics, the incidence was calculated to be about 1:400, and about 27% were related to base-metal alloys forremovable

Arne Hensten-Pettersen

1992-01-01

270

Antimicrobial and in vitro wound healing properties of novel clay based bionanocomposite films.  

PubMed

The present study investigates the development of methyl cellulose (MC)-sodium alginate (SA)-montmorillonite (MMT) clay based bionanocomposite films with interesting wound healing properties. The differential scanning calorimetry analysis of the composite films revealed presence of single glass transition temperature (Tg) confirming the miscible nature of the ternary blended films. The increase in MMT ratio in the composite films reduced the mobility of biopolymer chains (MC/SA) which increased the Tg of the film. Thermogravimetric analysis showed that dispersion of clay (MMT) at nano level significantly delayed the weight loss that correlated with higher thermal stability of the composite films. It was observed that the developed films were able to exhibit antimicrobial activity against four typical pathogenic bacteria found in the presence of wound. The developed films were able to significantly inhibit (10 mg/ml) the growth of Enterococcus faecium and Pseudomonas aeruginosa. In vitro scratch assay indicated potential wound closure activities of MC-2-4 bionanocomposite films at their respective highest subtoxic doses. In conclusion, these ternary bionanocomposite films were found to be promising systems for wound healing applications. PMID:24831081

Mishra, R K; Ramasamy, K; Lim, S M; Ismail, M F; Majeed, A B A

2014-08-01

271

Thickness microscopy based on photothermal radiometry for the measurement of thin films.  

PubMed

The photothermal detection technique is an innovative and non-contact method to investigate the properties of films on workpieces. This paper describes a novel experimental set-up for thickness microscopy based on photothermal radiometry. The correlation between the thermal wave signal and the film thickness is deduced and evaluated to determine the film thickness with a lateral resolution of less than 1mm. Results indicate that the thickness microscopy is a useful method to characterize thin films and has the potential to be applied in-process. PMID:19046925

Wang, Liping; Prekel, Helmut; Liu, Hengbiao; Deng, Yanzhuo; Hu, Jiming; Goch, Gert

2009-03-01

272

A Spray-Based Technique for the Production of MnS Thin Films.  

PubMed

A spray-based technique, originally developed for the production of semiconductor nanocrystals, is utilized for the preparation of high-quality nanocrystalline thin films, as demonstrated with manganese sulfide. The films are formed by the use of pneumatic-assisted thermospray or pneumatic nebulizers. Our simple, low-cost, and low-temperature process results in a dense and phase-pure grain structure. The concepts and benefits of this technique are described and discussed. The film characteristics show dependence on the experimental parameters, in particular the rate of solvent vaporization. Three alternative film formation mechanisms are suggested for cases with varied experimental conditions. PMID:25430787

Amirav, Lilac; Lifshitz, Efrat

2015-02-01

273

Elastohydrodynamic film thickness formula based on X-ray measurements with a synthetic paraffinic oil  

NASA Technical Reports Server (NTRS)

An empirical elastohydrodynamic film thickness formula for heavily loaded contacts based upon X-ray film thickness measurements made with a synthetic paraffinic oil is presented. The deduced relation was found to adequately reflect the high load dependence exhibited by the measured minimum film thickness data at high Hertizian contact stresses, that is, above 1.04 x 10 to the ninth N/sq m (150,000 psi). Comparisons were made with the numerical results from a theoretical isothermal film thickness formula. The effects of changes in contact geometry, material, and lubricant properties on the form of the empirical model are also discussed.

Loewenthal, S. H.; Parker, R. J.; Zaretsky, E. V.

1973-01-01

274

The Imagery of Rhetoric: Film and Academic Writing in the Discipline-based ESL Course.  

ERIC Educational Resources Information Center

Describes three reading/writing lessons on the topics of linguistics, environmental science, and anthropology used in a discipline-based college-level English as a second language course to illustrate how to use film to teach academic writing skills. Discusses how students analyze a film to help articulate the content of an essay or a book. (SR)

Kasper, Loretta F.

2000-01-01

275

Fluorescence from a gelatin-based film containing isolated and orientated single-walled carbon nanotubes  

E-print Network

Fluorescence from a gelatin-based film containing isolated and orientated single-walled carbon a technique to fabricate a gelatin thin film that contains orientated and individually dispersed single with gelatin, and the gelatin-SWNTs solution was spread over a SiO2 substrate by sliding a wire-bar uniformly

Maruyama, Shigeo

276

Room-Temperature Ammonia Sensor Based on CuxS Film  

Microsoft Academic Search

Gas sensing properties, surface chemical composition and morphology of CuxS-based films deposited on polyethylene and porous Si substrates were investigated. It was determined that the CuxS films show a reversible increase of resistance due to the exposure to ammonia gas at room temperature. The analysed samples were not sensitive to H2 and CO.

M. P. Casaletto; G. M. Ingo; S. Kaciulis; G. Mattogno; L. Pandolfi; A. Galdikas; A. Mironas; V. Strazdiene; I. Simkiene; A. Setkus; I. Ancutiene; V. Janickis

2000-01-01

277

Potential of Kaolin-based Particle Film Barriers for Formosan Subterranean Termite (Isoptera: Rhinotermitidae) Control  

Technology Transfer Automated Retrieval System (TEKTRAN)

Effects of three particle film products on Formosan subterranean termites, Coptotermes formosanus Shiraki, were evaluated in feeding, tunneling, and contact assays. The particle films, hydrophobic M96-018 and hydrophilic Surround and Surround WP are based on the inert clay mineral kaolin. In 2-week ...

278

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 polyvinilydene fluoride (PVDF) thin-film photopy- roelectric (PPE) sensors [1,2]. The PPE sensor exhibits-4005(98)00137-3 #12;A. Mandelis, J.A. Garcia / Sensors and Actuators B 49 (1998) 258­267 259 posed an optical

Mandelis, Andreas

279

Magnetic sensor based on side-polished fiber Bragg grating coated with iron film  

Microsoft Academic Search

A novel optical fiber magnetic sensor based on a side-polished fiber Bragg grating (FBG) coated with thin iron film was investigated. The sensor consists of a side-polished 10 mm FBG and two-layer thin iron films deposited on an interaction section 20 mum in diameter.

C. Tien; C. Hung; H. Chen; W. Liu; S. Lin

2006-01-01

280

STARCH/PULP-FIBER BASED PACKAGING FOAMS AND CAST FILMS CONTAINING ALASKAN FISH BY-PRODUCTS (WASTE)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Baked starch/pulp foams were prepared from formulations containing 0-25% (wt%) of processed Alaskan fish by-products that consisted mostly of salmon heads, pollock heads and pollock frames (bones and associated remains produced in the filleting operation). Fish by-products thermoformed well along wi...

281

One-dimensional semiconductor nanostructure based thin-film partial composite formed by transfer implantation for high-performance flexible and printable electronics at low temperature.  

PubMed

Having high bending stability and effective gate coupling, the one-dimensional semiconductor nanostructures (ODSNs)-based thin-film partial composite was demonstrated, and its feasibility was confirmed through fabricating the Si NW thin-film partial composite on the poly(4-vinylphenol) (PVP) layer, obtaining uniform and high-performance flexible field-effect transistors (FETs). With the thin-film partial composite optimized by controlling the key steps consisting of the two-dimensional random dispersion on the hydrophilic substrate of ODSNs and the pressure-induced transfer implantation of them into the uncured thin dielectric polymer layer, the multinanowire (NW) FET devices were simply fabricated. As the NW density increases, the on-current of NW FETs increases linearly, implying that uniform NW distribution can be obtained with random directions over the entire region of the substrate despite the simplicity of the drop-casting method. The implantation of NWs by mechanical transfer printing onto the PVP layer enhanced the gate coupling and bending stability. As a result, the enhancements of the field-effect mobility and subthreshold swing and the stable device operation up to a 2.5 mm radius bending situation were achieved without an additional top passivation. PMID:21174391

Moon, Kyeong-Ju; Lee, Tae-Il; Choi, Ji-Hyuk; Jeon, Joohee; Kang, Youn Hee; Kar, Jyoti Prakash; Kang, Jung Han; Yun, Ilgu; Myoung, Jae-Min

2011-01-25

282

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

283

Water-based preparation of highly oleophobic thin films through aggregation of nanoparticles using layer-by-layer treatment  

NASA Astrophysics Data System (ADS)

The layer-by-layer (LBL) adsorption technique has potential for controlling the surface wettability. In this study, we controlled surface wettability between "superhydrophobic and oleophobic" and "hydrophobic and oleophilic" by LBL process on TiO2 nanoparticle with hydrophobic polymer and hydrophilic polymer. From the cast coating with LBL process on TiO2 nanoparticle, the surface showed "superhydophobic and oleophobic" when the top surface was hydrophobic polymer, on the other hand, the surface showed "hydrophobic and oleophilic" when the top surface was hydrophilic polymer. The LBL process also affected to the structure of TiO2 nanoparticle/polymer composite, and TiO2 nanoparticle were aggregated with polymers in LBL process. In the condition of the aggregated diameter of TiO2 nanoparticle/polymer composite around 10 ?m in solution, the oleohobicity of spray coated film was enhanced with its hierarchical structure (static contact angles of rapeseed oil of 150° and hexadecane of 145°) "Superhydrophobic and high oleophobic" surfaces generated from all water-based dispersions are expected for application in technologies that need to avoid organic solvents.

Nishizawa, Shingo; Shiratori, Seimei

2012-12-01

284

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

285

High performance thin film transistors based on regioregular poly(3-dodecylthiophene)-sorted large diameter semiconducting single-walled carbon nanotubes.  

PubMed

In this work, a simple and rapid method to selectively sort semiconducting-SWCNTs (sc-SWCNTs) with large diameters using regioregular poly(3-dodecylthiophene) (rr-P3DDT) is presented. The absorption spectra and Raman spectra demonstrated that metallic species of arc discharge SWCNTs were effectively removed after interaction with rr-P3DDT in toluene with the aid of sonication and centrifugation. The sorted sc-SWCNT inks have been directly used to fabricate thin film transistors (TFTs) by dip-coating, drop-casting and inkjet printing. TFTs with an effective mobility of ?34 cm(2) V(-1) s(-1) and on-off ratios of ?10(7) have been achieved by dip coating and drop casting the ink on SiO2/Si substrates with pre-patterned interdigitated gold electrode arrays. The printed devices also showed excellent electrical properties with a mobility of up to 6.6 cm(2) V(-1) s(-1) and on-off ratios of up to 10(5). Printed inverters based on the TFTs have been constructed on glass substrates, showing a maximum voltage gain of 112 at a V(dd) of -5 V. This work paves the way for making printable logic circuits for real applications. PMID:23595234

Wang, Chao; Qian, Long; Xu, Wenya; Nie, Shuhong; Gu, Weibing; Zhang, Jianhui; Zhao, Jianwen; Lin, Jian; Chen, Zheng; Cui, Zheng

2013-05-21

286

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

287

Characterization of thin film properties of melamine based dendrimer nanoparticles  

E-print Network

film. Discontinuity of tangential separation explains that contraction separation developed in (a)radial direction prior to (b)tangential separation????????????..???????.....44 19 (a) Digital Instruments Nanoscope AFM/STM for scanning...

Boo, Woong Jae

2005-02-17

288

Optical isolator based on mode conversion in magnetic garnet films.  

PubMed

Calculations are presented describing a novel optical isolator which works by complete TE(0)-TM(0) mode conversion in magnetic garnet films caused by stress-induced optical anisotropy (50%) and by Faraday rotation (50%). These conversions take place along two different, perpendicular light paths in the same crystal that are connected by an integrated mirror. Possible tolerances of the film parameters are given so that a 30-dB isolation is still guaranteed. PMID:20490145

Hemme, H; Dötsch, H; Menzler, H P

1987-09-15

289

An interferometric humidity sensor based on a thin gelatin film  

NASA Astrophysics Data System (ADS)

Gelatin thin films inserted in a Mach - Zehnder interferometer were used to monitor Relative Humidity (RH). When RH varied, gelatin film thickness and refractive index also changed. As a result interference pattern moved horizontally. A fixed detector, with a pinhole in front of it, was placed at the interference pattern. It sampled the pattern when it moved. These intensity values were used to find a calibration plot relating intensity as a function of RH.

Calixto, Sergio; Montes-Perez, Areli

2014-07-01

290

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

291

Millimeter wave phase shifter based on ferromagnetic resonance in a hexagonal barium ferrite thin film  

E-print Network

Millimeter wave phase shifter based on ferromagnetic resonance in a hexagonal barium ferrite thin of an M-type barium ferrite BaM thin film prepared by pulsed laser deposition and a coplanar waveguide

292

Thin film lithium-based batteries and electrochromic devices fabricated with nanocomposite electrode materials  

DOEpatents

Thin-film lithium-based batteries and electrochromic devices (10) are fabricated with positive electrodes (12) comprising a nanocomposite material composed of lithiated metal oxide nanoparticles (40) dispersed in a matrix composed of lithium tungsten oxide.

Gillaspie, Dane T; Lee, Se-Hee; Tracy, C. Edwin; Pitts, John Roland

2014-02-04

293

A Disposable Biosensor for Organophosphorus Nerve Agents Based on Carbon Nanotubes Modified Thick Film Strip Electrode  

E-print Network

Full Paper A Disposable Biosensor for Organophosphorus Nerve Agents Based on Carbon Nanotubes (CNTs) modified thick film strip electrode for organophosphorus (OP) insecticides was developed, Biosensor, Organophosphorus insecticides, Acetyl- cholinesterase, Paraoxons 1. Introduction Organophosphorus

Chen, Wilfred

294

Method of casting aerogels  

DOEpatents

The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.

Poco, J.F.

1993-09-07

295

Method of casting aerogels  

DOEpatents

The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm.sup.3 to 0.6 g/cm.sup.3. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of alcogel which occurs during the drying step of supercritical extraction of solvent.

Poco, John F. (Livermore, CA)

1993-01-01

296

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

297

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

NASA Astrophysics Data System (ADS)

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 the seed layered films by chemical bath deposition (CBD). The influence of seed layer on the structural, surface morphological, optical and wettability behavior of the ZnO thin films were systematically investigated. The XRD analysis confirms the high crystalline nature of both the seed layer and corresponding ZnO micro/nanostructured films with a perfect hexagonal structure oriented along (0 0 2) direction. The surface morphology revels a complex and orientated hierarchical based ZnO structured films with diverse shapes from plates to hexagonal rod-like crystal to tube-like structure and even much more complex needle-like shapes during secondary nucleation, by changing the seed layer conditions. The water contact angle (WCA) measurements on hierarchical ZnO structured films are completely examined to study its surface wettability behavior for its suitability in future self-cleaning application. Photoluminescence (PL) spectra of the ZnO structured film exhibit UV and visible emissions in the range of 420-500 nm. The present approach demonstrates its potential for low-temperature, large-scale, controlled synthesis of crystalline hierarchical ZnO nanostructures films.

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

2011-05-01

298

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

E-print Network

FORMATION OF THIN FILM Tl-BASED HIGH-Tc SUPERCONDUCTING OXIDES FROM AMORPHOUS ALLOY PRECURSORS A Thesis JOHN CHARLES WILLIAMS Submitted to the Once of Graduate Studies of Texas A&M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 1991 Major Subject: Physics FORMATION OF THIN FILM Tl BASED HIGH Tc SUPERCONDUCTING OXIDES FROM AMORPHOUS ALLOY PRECURSORS A Thesis JOHN CHARLES WILLIAMS Approved as to style and content by: Donald G. Naugle...

Williams, John Charles

2012-06-07

299

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

300

The Surface Structure and Thermal Properties of Novel Polymer Composite Films Based on Partially Phosphorylated Poly(vinyl alcohol) with Aluminum Phosphate  

PubMed Central

Partially phosphorylated polyvinyl alcohol (PPVA) with aluminum phosphate (ALPO4) composites was synthesized by solution casting technique to produce (PPVA)100?y ? (ALPO4)y (y?=?0, 1, and 2). The surface structure and thermal properties of the films were characterized using Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The results showed that the films have higher thermal stability with strong bonding between PPVA and ALPO4. PMID:25506069

Mohamed Saat, Asmalina

2014-01-01

301

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

302

Defects and interfaces in nitride-based thin film heterostructures  

NASA Astrophysics Data System (ADS)

The characteristics of the growth of III-Nitrides on sapphire and silicon were studied by different transmission electron microscopy (TEM) techniques including multiple dark field imaging, diffraction contrast analysis, convergent beam electron diffraction, high-resolution TEM, atomic image simulations. The following types of defects were found to exist in the thin films of III-Nitrides: dislocations, stacking faults, inversion domain boundaries, low angle tilt sub-grain boundaries. The thorough study of the structure of the extended defects in AlN, GaN and GaAlN layers was carried out. Predominant defects existing in AlN films on sapphire were determined to be inversion domain boundaries and edge dislocations (on the basal plane of sapphire); and low-energy intrinsic stacking faults of type Isb1 (on the r-plane sapphire). The atomic structure of the inversion domain boundaries and stacking faults was determined by careful calculations of different atomic models using multislice image simulation method. Two distinctive types of the microstructure were found to be characteristic for the GaN/GaAlN films grown on (0001) sapphire. Films grown under slightly non-optimized conditions were found to contain high, up to the 10sp9 cmsp2, density of inversion domains as well as screw, mixed and edge type dislocations with the average density of 10sp9{-}10sp{10} cmsp{-2}. Optimization of the growth conditions resulted in smoother surfaces of the films, absence of inversion domains and low (down to 10sp7 cmsp{-2} in the device quality films) density of screw and mixed type dislocations. The typical defects present in these optimized GaN and GaN/GaAlN thin films were found to be threading dislocations with 1/3 (1120) Burgers vector associated with low angle tilt sub-grain boundaries. Although the density of b = 1/3 (1120) edge dislocations was found to be about 10sp{10}{-}10sp{11}\\ cmsp{-2}, the films exhibited the device-quality electrical characteristics. The possibility for using the ZnO/sapphire heterostructures as a buffer layer for growing III-Nitrides was investigated. Correlations between the atomic structure and optical properties (photoluminescence) of defects and interfaces in III-Nitride thin film heterostructures and their implications on device performance are discussed.

Dovidenko, Katharine

303

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

304

System for holographic interferometry based on bacteriorhodopsin films  

NASA Astrophysics Data System (ADS)

Films made from genetically modified bacteriorhodopsins (BR) are attractive media for holographic recording. A holographic camera system is presented which uses BR-films as photowritable-photoerasable optical recording media. This camera system is useful in applications like non-destructive testing, vibration analysis and size measurement. To our knowledge this is the first technical system were a biological material, the BR-films, are employed as a performance determining component. The camera head is dust proof sealed and internally damped for applications in a technical environment. All control and display devices are mounted in a separate 19' rack which comes with the system. The system can be easily switched between various holographic measurement techniques under software control, among them double-exposure, time-averaging, real-time and phase-shifting interferometry. The system is able to resolve deformations with a resolution down to 5 nm ((lambda) /100) and operates at 12 frames/second. A variable read-out magnification allows to take advantage of the very high resolution of the BR-films which is beyond 5000 lines/mm. Polarization recording in BR-films is employed to obtain a high signal-to-noise ratio even at low exposures of 100 (mu) J/cm2. The recording mechanism at low light levels is discussed in detail.

Hampp, Norbert A.; Juchem, Thorsten

2001-10-01

305

Dynamic Water Modeling and Application of Billet Continuous Casting  

Microsoft Academic Search

The continuous casting process is used for solidifying molten steel into semi-finished steel. The technology of secondary cooling is extremely important for output of the casting machine and billet quality. A dynamic water model was introduced, including solidification model in the secondary cooling, feedforward control strategy based on continuous temperature measurement in tundish, and feedback control strategy based on surface

Wen-hong LIU; Zhi XIE; Zhen-ping JI; Biao WANG; Zhao-yi LAI; Guang-lin JIA

2008-01-01

306

3D stress simulation and parameter design during twin-roll casting of 304 stainless steel based on the Anand model  

NASA Astrophysics Data System (ADS)

This study first investigated cracks on the surface of an actual steel strip. Formulating the Anand model in ANSYS software, we then simulated the stress field in the molten pool of type 304 stainless steel during the twin-roll casting process. Parameters affecting the stress distribution in the molten pool were analyzed in detail and optimized. After twin-roll casting, a large number of transgranular and intergranular cracks resided on the surface of the thin steel strip, and followed a tortuous path. In the molten pool, stress was enhanced at the exit and at the roller contact positions. The stress at the exit decreased with increasing casting speed and pouring temperature. To ensure high quality of the fabricated strips, the casting speed and pouring temperature should be controlled above 0.7 m/s and 1520°C, respectively.

Guo, Jing; Liu, Yuan-yuan; Liu, Li-gang; Zhang, Yue; Yang, Qing-xiang

2014-07-01

307

Theoretical investigation of acoustic wave devices based on different piezoelectric films deposited on silicon carbide  

NASA Astrophysics Data System (ADS)

Performances of acoustic wave (AW) devices based on silicon carbide (SiC) substrates are theoretically studied, in which two types of piezoelectric films of ZnO and AlN deposited on 4H-SiC and 3C-SiC substrates are adopted. The phase velocities (PV), electromechanical coupling coefficients (ECC), and temperature coefficients of frequency (TCF) for three AW modes (Rayleigh wave, A0 and S0 modes of Lamb wave) often used in AW devices are calculated based on four types of configurations of interdigital transducers (IDTs). It is found that that the ZnO piezoelectric film is proper for the AW device operating in the low-frequency range because a high ECC can be realized using a thin ZnO film. The AlN piezoelectric film is proper for the device operating in the high-frequency range in virtue of the high PV of AlN, which can increase the finger width of the IDT. Generally, in the low-frequency Lamb wave devices using ZnO piezoelectric films with small normalized thicknesses of films to wavelengths hf/?, thin SiC substrates can increase ECCs but induce high TCFs simultaneously. In the high-frequency device with a large hf/?, the S0 mode of Lamb wave based on the AlN piezoelectric film deposited on a thick SiC substrate exhibits high performances by simultaneously considering the PV, ECC, and TCF.

Fan, Li; Zhang, Shu-yi; Ge, Huan; Zhang, Hui

2013-07-01

308

Antimicrobial packaging of chicken fillets based on the release of carvacrol from chitosan/cyclodextrin films.  

PubMed

Chitosan/cyclodextrin films (CS:CD) incorporating carvacrol were obtained by casting, and conditioned at 23°C and 75% relative humidity prior to being immersed in liquid carvacrol until they reached sorption equilibrium. In a previous work, the in vitro antimicrobial activity of these films was studied. In this work, active films were used to inhibit microbial growth in packaged chicken breast fillets. Samples of CS:CD films loaded with carvacrol, of different sizes and thus with different quantities of antimicrobial agent, were stuck to the aluminium lid used to seal PP/EVOH/PP cups containing 25g of chicken fillets. These samples were stored for 9days at 4°C. The packages were hermetically sealed and it was confirmed that they provided an infinite barrier to carvacrol. The partition of the antimicrobial agent within the food/packaging system was analysed. The antimicrobial devices rapidly released a large percentage of the agent load, amounts that were gained by the adhesive coating of the lid and especially by the chicken fillets. The latter were the main sorbent phase, with average concentrations ranging between 200 and 5000mg/Kg during the period of storage. The microbiota of the packaged fresh chicken fillets - mesophiles, psychrophiles, Pseudomonas spp., enterobacteria, lactic acid bacteria and yeasts and fungi - were analysed and monitored during storage. A general microbial inhibition was observed, increasing with the size of the active device. Inhibition with a 24cm(2) device ranged from 0.3 log reductions against lactic acid bacteria to 1.8logs against yeasts and fungi. However, the large amount of antimicrobial that was sorbed or that reacted with the fillet caused an unacceptable sensory deterioration. These high sorption values are probably due to a great chemical compatibility between chicken proteins and carvacrol. PMID:25087205

Higueras, Laura; López-Carballo, Gracia; Hernández-Muñoz, Pilar; Catalá, Ramón; Gavara, Rafael

2014-10-01

309

VAl-Based Thermoelectric Thin Films Prepared by a Sputtering Technique  

NASA Astrophysics Data System (ADS)

In this study we prepared thin-film samples of the Fe2VAl-based Heusler phase by means of radio-frequency magnetron sputtering. The Fe2VAl-based Heusler phase was grown epitaxially, keeping the root-mean-square surface roughness smoother than 20 nm, even when the thickness of the samples exceeded 1000 nm. The composition of the samples was controlled via both target composition and the area of a small vanadium chip placed on the target. We succeeded in obtaining samples that were free from precipitation of a secondary phase. It was confirmed that the lattice thermal conductivity of the film samples can be reduced, irrespective of film thickness, and that the Seebeck coefficient was essentially the same as that of the bulk samples. These experimental results indicate that thin-film Fe2VAl-based Heusler alloys have potential as practical thermoelectric materials.

Furuta, Yukihiro; Kato, Keisuke; Miyawaki, Tetsuya; Asano, Hidefumi; Takeuchi, Tsunehiro

2014-06-01

310

Polymeric acrylate-based hybrid films containing lead and iron patterned by UV photo-polymerization.  

PubMed

The development and processing of hybrid inorganic-organic thin film materials plays a critical role in advancing interdisciplinary sciences and device manufacturing. Here we present a novel approach to synthesize and deposit acrylate-containing organic/inorganic hybrid films. The material is based on a chemical solution and includes specifically desired metal dopants that are fully integrated into the backbone of the polymer structure. The film can be deposited by simple spin coating, and we confer photosensitive properties to the material making it directly patterned by traditional UV photolithography techniques. Film thickness, chemical characterization, and wet/dry etching capability of the film are also investigated. We believe this innovative material has the potential to be used in a broad range of applications for electronic, photonic, biology, and other interdisciplinary fields. PMID:19795818

Han, Huilan; Bissell, John; Yaghmaie, Frank; Davis, Cristina E

2010-01-01

311

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

312

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

313

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

314

FILMING OF 'CONTACT' AT LC39 PRESS SITE  

NASA Technical Reports Server (NTRS)

Warner Bros.' cast and crew are filming scenes for the movie 'Contact' at Kennedy Space Center's Launch Complex 39 Press Site on January 30. The screenplay for 'Contact' is based on the best- selling novel by the late astronomer Carl Sagan. The cast includes Jodie Foster, Matthew McConaughey, John Hurt, James Woods, Tom Skerritt, David Morse, William Fichtner, Rob Lowe and Angela Bassett. Described by Warner Bros. as a science fiction drama, 'Contact' will depict humankind's first encounter with evidence of extraterrestrial life.

1997-01-01

315

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

316

Flexible fluidic microchips based on thermoformed and locally modified thin polymer films.  

PubMed

This paper presents a fundamentally new approach for the manufacturing and the possible applications of lab on a chip devices, mainly in the form of disposable fluidic microchips for life sciences applications. The new technology approach is based on a novel microscale thermoforming of thin polymer films as core process. The flexibility not only of the semi-finished but partly also of the finished products in the form of film chips could enable future reel to reel processes in production but also in application. The central so-called 'microthermoforming' process can be surrounded by pairs of associated pre- and postprocesses for micro- and nanopatterned surface and bulk modification or functionalisation of the formed films. This new approach of microscale thermoforming of thin polymer film substrates overlaid with a split local modification of the films is called 'SMART', which stands for 'substrate modification and replication by thermoforming'. In the process, still on the unformed, plane film, the material modifications of the preprocess define the locations where later, then on the spatially formed film, the postprocess generates the final local modifications. So, one can obtain highly resolved modification patterns also on hardly accessible side walls and even behind undercuts. As a first application of the new technology, we present a flexible chip-sized scaffold for three dimensional cell cultivation in the form of a microcontainer array. The spatially warped container walls have been provided with micropores, cell adhesion micropatterns and thin film microelectrodes. PMID:18818815

Truckenmüller, R; Giselbrecht, S; van Blitterswijk, C; Dambrowsky, N; Gottwald, E; Mappes, T; Rolletschek, A; Saile, V; Trautmann, C; Weibezahn, K-F; Welle, A

2008-09-01

317

Optical spectroscopy of conducting Schiff-base polymer films  

NASA Astrophysics Data System (ADS)

Polymer samples of complexes of divalent copper with the H2msalpn-1,3 ligand have been studied by optical spectroscopy. The optical density spectra of metal-polymer films have been analyzed taking into account the influence of preliminary thermal treatment. The spectral dependences of the absorption coefficient and optical band gap are determined for different experimental conditions.

Avanesyan, V. T.; Vodkailo, E. G.

2012-04-01

318

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

319

Photostable solar concentrators based on fluorescent glass films  

Microsoft Academic Search

Efficient luminescent solar concentrators (LSC) were prepared by deposition of organi- cally modified sol-gel films doped by photostable perylimide dyes on plexiglas substrates. The absorption spectra of these dyes extends from 420 to 620 nm covering the visible part of the solar spectrum and the emission is between 550 and 750 nm, close to the optimum response of silicon and

Renata Reisfeld; Dimitri Shamrakov; Christian Jorgensen

1994-01-01

320

Architectural optimization of an epoxy-based hybrid sol-gel coating for the corrosion protection of a cast Elektron21 magnesium alloy  

NASA Astrophysics Data System (ADS)

An epoxy-based hybrid sol-gel coating was prepared in various architectural configurations has been studied for the corrosion protection of a cast Elektron21 magnesium alloy. The creation of a single layer of this coating presents defects consisting of macro-pores and protuberances, which opens access for corrosive species to reach the metallic substrate. These defects are suspected to result from the high reactivity of the substrate, as well as to the irregular topography of the substrate disrupted by the microstructure of the own magnesium alloy. Hence, a sol-gel coating in bilayer architecture is proposed, where the first layer would “inert” the surface of the magnesium substrate, and the second layer would cover the defects of the first layer and also thickening the coating. The morphological characteristics of the sol-gel coatings were analyzed by scanning electron microscopy (SEM), and their corrosion behavior was evaluated by OCP (open circuit potential) monitoring and electrochemical impedance spectroscopy (EIS) in chloride media. It is shown that both the architectural arrangement and the individual thickness of the first and second layers have an important influence on the anticorrosion performances of the protective system, just as much as its global thickness.

Murillo-Gutiérrez, N. V.; Ansart, F.; Bonino, J.-P.; Kunst, S. R.; Malfatti, C. F.

2014-08-01

321

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

322

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

323

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

324

Electrical characteristics of UV photodetectors based on ZnO/diamond film structure  

NASA Astrophysics Data System (ADS)

Ultraviolet photodetectors based on ZnO/diamond film structure were fabricated. The properties of Au/ZnO contacts and effects of grain sizes on the electrical characteristics of photodetectors were discussed. Due to the bombardment with Au atoms and the annealing process, fine ohmic contacts were formed between Au electrodes and ZnO films. Dark currents and photocurrents of the photodetectors were related to sputtering time and the grain size of ZnO films. For the photodetector with a bigger grain size, a lower dark current and a higher photocurrent were obtained under 10 V bias voltage. The time-dependent photocurrent confirmed the carrier trapping effect.

Liu, Jianmin; Xia, Yiben; Wang, Linjun; Su, Qingfeng; Shi, Weimin

2007-04-01

325

Millimeter wave phase shifter based on ferromagnetic resonance in a hexagonal barium ferrite thin film  

NASA Astrophysics Data System (ADS)

A hexagonal ferrite thin film-based planar millimeter-wave phase shifter was demonstrated. The device made use of an M-type barium ferrite (BaM) thin film prepared by pulsed laser deposition and a coplanar waveguide geometry. The phase tuning relied on ferromagnetic resonance in the BaM film. The device showed a phase tuning rate of 43°/(mm kOe) and an insertion loss of 3.1 dB/mm in the on-resonance regime. In off-resonance regimes, the device showed smaller loss and smaller tuning rates. The experimental results were confirmed by theoretical calculations.

Wang, Zihui; Song, Young-Yeal; Sun, Yiyan; Bevivino, Joshua; Wu, Mingzhong; Veerakumar, V.; Fal, Timothy J.; Camley, Robert E.

2010-08-01

326

Large oriented arrays and continuous films of TiO(2)-based nanotubes.  

PubMed

We report for the first time a one-step, templateless method to directly prepare large arrays of oriented TiO2-based nanotubes and continuous films. These titania nanostructures can also be easily prepared as conformal coatings on a substrate. The nanostructured films were formed on a Ti substrate seeded with TiO2 nanoparticles. SEM and TEM results suggested that a folding mechanism of sheetlike structures was involved in the formation of the nanotubes. The oriented arrays of TiO2 nanotubes, continuous films, and coatings are expected to have potentials for applications in catalysis, filtration, sensing, photovoltaic cells, and high surface area electrodes. PMID:14531662

Tian, Zhengrong R; Voigt, James A; Liu, Jun; McKenzie, Bonnie; Xu, Huifang

2003-10-15

327

Heterojunction thin films based on multifunctional metal oxides for photovoltaic application  

SciTech Connect

Metal oxides based multifunctional heterojunction thin films of ZnO/SnO{sub 2} and ZnO/SnO{sub 2}/CuO QDs were prepared by spin-coating technique. The crystallographic properties and the surface morphologies of the films were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The optical absorption studies revealed that the film thickness has considerable effect on the band gap values and is found to be in the range of 3.73–3.48 eV. The photoluminescence spectra showed several weak visible emission peaks related to the deep level defects (450-575 nm). Finally, the current density-voltage (J-V) characteristic of ZnO/SnO{sub 2}/CuO QDs (ZSCI) based heterojunction thin film coated on ITO is also reported.

Prabhu, M.; Soundararajan, N.; Ramachandran, K. [School of Physics, Madurai Kamaraj University, Madurai - 625021 (India); Marikkannan, M.; Mayandi, J. [School of Chemistry, Madurai Kamaraj University, Madurai - 625021 (India)

2014-04-24

328

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

329

Reactive coating of soybean oil-based polymer on nanofibrillated cellulose film for water vapor barrier packaging.  

PubMed

Nanofibrillated cellulose (NFC) easily forms a high strength film but is unable to withstand the influence of water vapor when used in high moisture situations. The water vapor transmission rate (WVTR) of a NFC film was as high as 5088 g/m(2)24h (38 °C, 90% RH). The addition of beeswax latex in a NFC casting film (NFX) lowered the WVTR to 3918 g/m(2)24h. To further reduce the WVTR, a coating agent comprised of acrylated epoxidized soybean oil (AESO) and 3-aminopropyltriethoxysilane (APTS) was applied onto the NFX film using a rod coater. A combination of the suitable AESO/APTS ratio, initiator dosing, curing time and temperature could reduce the WVTR to 188 g/m(2) 24h when the coat weight was 5 g/m(2). Moreover, the coated NFX film was highly hydrophobic along with the improved transparency and thermal stability. This biodegradable polymer-coated NFC film can be used as potential packaging barrier in certain areas. PMID:25037383

Lu, Peng; Xiao, Huining; Zhang, Weiwei; Gong, Glen

2014-10-13

330

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

331

Tl-based superconducting films prepared by aerosol spray deposition and thallinated in an open system  

Microsoft Academic Search

Superconducting Tl-based films were prepared on a LaAlO3 single crystal substrate. Spray pyrolysis of Ba, Ca and Cu nitrate solutions was used for deposition of the precursor films.\\u000a They were subsequently ex-situ thallinated in flowing oxygen (open system). While the superconducting Tl-2212 phase formed at an annealing temperature\\u000a of 880°C, thallination at 900°C led to the formation of a Tl-2223

Zuzana Matkovicová; Vladimír Štrbík; Gustav Plesch; Michaela Valeriánová; Agáta Dujavová

2007-01-01

332

Thin-film deposition of an organic magnet based on vanadium methyl tricyanoethylenecarboxylate.  

PubMed

The preparation and characterization of a new thin-film organic-based magnet V[MeTCEC]x (V = vanadium; MeTCEC = methyl tricaynoethylenecarboxylate) via low-temperature chemical vapor deposition (50 °C) is reported. These thin films exhibit room-temperature magnetic ordering and semiconducting behavior, demonstrating the ability of tuning their magnetic, and potentially spintronic, functionality via chemical modification of the organic ligand. PMID:25327816

Lu, Yu; Harberts, Megan; Kao, Chi-Yueh; Yu, Howard; Johnston-Halperin, Ezekiel; Epstein, Arthur J

2014-12-01

333

Room-temperature-functioning ammonia sensor based on solid-state Cu x S films  

Microsoft Academic Search

Resistive gas sensors based on copper sulphide (CuxS) are produced when a thick-film of the CuxS is chemically deposited on the polyethylene (PE) film substrates. The resistance response to gases is investigated for the sensors at the temperatures from 291 to 313 K in air. A correlation of the response to gas with the technology is analysed. It is demonstrated

A Galdikas; A Mironas; V Janickis

2000-01-01

334

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

335

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

336

Research of the Automatic Shrinking-Film Labeling Machine Based on the Data Bus  

Microsoft Academic Search

This paper introduces a specific object-oriented, automatic shrinking-film labeling machine control system based on the data bus. It analyzes the structure, control requirements and motion regulation of the shrinking-film labeling machine. It builds the mathematical model of the servo motor and the system, builds the experimental platform. Multiple sets of experimental datas and curves are obtained after several experiments. The

Cheng He

2011-01-01

337

THE FUTURE DEVELOPMENT OF ENERGETIC THIN-FILM PROCESSES FOR SPACED BASED DEPOSITIONS  

Microsoft Academic Search

NASA's Lunar-Mars proposal (January 14, 2004) plans to use the Moon as an outpost for future voyages to Mars and beyond. The ability to deposit high performance thin-film coatings in the vacuum of lunar-space will be extremely valuable for executing many aspects of this new mission. Space-based thin-film depositions will enable the future development of flexible large- area space antennae

Michael L. Fulton

338

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

339

The Electrochemical and Thermal Stability of PEDOT-based Composite Films  

Microsoft Academic Search

The electrically conductive composite films based on poly(3,4-ethylenedioxythiophene) (PEDOT) were synthesized. The PEDOT\\/silicate composite was prepared by the in-situ oxidative polymerization of EDOT monomer using ferric toluene sulfonate (FTS) oxidant in which tetraethylorthosilicate was added to form inorganic silicate network by sol-gel transformation. The PEDOT-gold composite film was also prepared by the in-situ redox reaction between PEDOT in neutral state

Boyoung Kim; Youngkwan Lee; Jae-Do Nam; Yongkeun Son

2006-01-01

340

Structure and Function of Protein-Based Edible Films and Coatings  

Microsoft Academic Search

\\u000a Research and development on films and coatings made from various agricultural proteins has been conducted over the past 20\\u000a years, but is of heightened interest, due to the demand for environmentally-friendly, renewable replacements for petroleum-based\\u000a polymeric materials and plastics. To address this demand, films and coatings have been made from renewable resources, such\\u000a as casein, whey, soy, corn zein, collagen,

Kirsten Dangaran; Peggy M. Tomasula; Phoebe Qi

341

A comparison of film-based tomography and computed tomography for advanced ceramic materials  

Microsoft Academic Search

An X-ray computed tomography (CT) imaging system and an analog tomographic system were used to examine a green-state SiâNâ test specimen. The CT system used was a state-of-the-art medical CT scanner with a polychromatic source. The film-based tomography system was a Siemens Optiplanimat with tungsten target and 2.5-mm Al filtration. It was operated in one scan pattern. Single-emulsion industrial film

W. A. Ellingson; M. W. Vannier; R. J. Kriz

1987-01-01

342

Cucurbit[8]uril-based stimuli-responsive films as a sacrificial layer for preparation of free-standing thin films.  

PubMed

A pseudo-polycation was prepared based on the supramolecular cucurbit[8]uril ternary complex. It was then layer-by-layer assembled with poly(acrylic acid) to fabricate a stimuli-responsive film, which exhibited disassembly properties in response to stimuli, providing a supramolecular route for the fabrication of free-standing thin films. PMID:25370182

Li, Dan-Dan; Chen, Xia-Chao; Ren, Ke-Feng; Ji, Jian

2015-01-15

343

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

344

Switching dynamics in lead-based thin film ferroelectrics  

NASA Astrophysics Data System (ADS)

Fast polarization logic state switching is a desirable quality of ferroelectric thin films for nonvolatile random access memories. The goal of this research was to systematically understand the influence of the ferroelectric microstructural properties (i.e. tetragonality) and the ferroelectric/electrode interface on the switching dynamics. The experiments were conducted using PZT epitaxial thin films in which the c/a ratio and domain structure was varied by compositional alterations with the addition of lanthanum doping, and in PZT films with fixed composition but systematically varied microstructure using thickness variations. The influence of the ferroelectric/electrode interface was also investigated using PNZT polycrystalline ferroelectrics with SRO, LSCO and Pt electrodes. The experimental parameter used to describe the switching dynamics for this study was the activation field. The activation field describes the rate of reversal of polarization i = dP/dt, where i is the switching current density, and reflects the switching dynamics of the ferroelectric. The activation field also provides an indication of the switching performance of a ferroelectric capacitor and likewise was used as a relative parameter to study the relationship between changes in the microstructure of the capacitor and the switching process. Additionally, it was established that the activation field determined using imax was independent of the resistive load, capacitor area, testing pulse width and write/read delay time and was therefore used as a reliable parameter to give information about the ferroelectric dynamics. The research studies supported the theoretical interpretation by demonstrating experimentally that the tetragonality of the ferroelectric has a significant influence on the activation field. The tetragonality was shown to have a more significant influence on the activation field than the type of dopant. Thinner films showed a higher tetragonality and therefore a larger activation field. Finally, the ferroelectric/electrode interface also proved to affect the activation field. The higher activation field was associated with capacitors having a barrier at the ferroelectric/electric interface. (Abstract shortened by UMI.)

Jenkins, Ingrid Gwyn

345

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

346

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

347

Bio-based biodegradable film to replace the standard polyethylene cover for silage conservation.  

PubMed

The research was aimed at studying whether the polyethylene (PE) film currently used to cover maize silage could be replaced with bio-based biodegradable films, and at determining the effects on the fermentative and microbiological quality of the resulting silages in laboratory silo conditions. Biodegradable plastic film made in 2 different formulations, MB1 and MB2, was compared with a conventional 120-?m-thick PE film. A whole maize crop was chopped; ensiled in MB1, MB2, and PE plastic bags, 12.5kg of fresh weight per bag; and opened after 170d of conservation. At silo opening, the microbial and fermentative quality of the silage was analyzed in the uppermost layer (0 to 50mm from the surface) and in the whole mass of the silo. All the silages were well fermented with little differences in fermentative quality between the treatments, although differences in the mold count and aerobic stability were observed in trial 1 for the MB1 silage. These results have shown the possibility of successfully developing a biodegradable cover for silage for up to 6mo after ensiling. The MB2 film allowed a good silage quality to be obtained even in the uppermost part of the silage close to the plastic film up to 170d of conservation, with similar results to those obtained with the PE film. The promising results of this experiment indicate that the development of new degradable materials to cover silage till 6mo after ensiling could be possible. PMID:25468689

Borreani, Giorgio; Tabacco, Ernesto

2015-01-01

348

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

349

Water-repellant properties of mixed films with TiO2 base  

NASA Astrophysics Data System (ADS)

This report is focused on the water-repellant properties of TiO2 and its mixed films with adding certain oxides or fluorides. It is well known that TiO2 films and powders can be used as a water splitting coating due to its photocatalytic reaction. With the addition of the second material, the absorption band and the microstructure of TiO2 films are changed, which will influence their photocatalytic properties. Mixed films based on TiO2 with various compositions were deposited on unheated BK7 glass substrates by e-beam gun coevaporation technique with ion bombardments. Some of the films were also deposited at a glass substrate temperature of 300 degree(s)C without ion assistance. The degrees of water repellence of these films before and after UV irradiation were evaluated in terms of the contact angle of the deionized water on the coating surface. The correlation between the composition, UV-light exposure time and the water-repellant properties of the mixed films ere evaluated and discussed.

Tsai, Rung-Ywan; Wei, Chaur-Tsang; Lin, Dhei-Jhai; Lee, William J.; Hua, Mu-Yi

2000-05-01

350

Advanced Pattern Material for Investment Casting Applications  

SciTech Connect

Cleveland Tool and Machine (CTM) of Cleveland, Ohio in conjunction with Harrington Product Development Center (HPDC) of Cincinnati, Ohio have developed an advanced, dimensionally accurate, temperature-stable, energy-efficient and cost-effective material and process to manufacture patterns for the investment casting industry. In the proposed technology, FOPAT (aFOam PATtern material) has been developed which is especially compatible with the investment casting process and offers the following advantages: increased dimensional accuracy; increased temperature stability; lower cost per pattern; less energy consumption per pattern; decreased cost of pattern making equipment; decreased tooling cost; increased casting yield. The present method for investment casting is "the lost wax" process, which is exactly that, the use of wax as a pattern material, which is then melted out or "lost" from the ceramic shell. The molten metal is then poured into the ceramic shell to produce a metal casting. This process goes back thousands of years and while there have been improvements in the wax and processing technology, the material is basically the same, wax. The proposed technology is based upon an established industrial process of "Reaction Injection Molding" (RIM) where two components react when mixed and then "molded" to form a part. The proposed technology has been modified and improved with the needs of investment casting in mind. A proprietary mix of components has been formulated which react and expand to form a foam-like product. The result is an investment casting pattern with smooth surface finish and excellent dimensional predictability along with the other key benefits listed above.

F. Douglas Neece Neil Chaudhry

2006-02-08

351

Production scheduling in a steelmaking-continuous casting plant  

Microsoft Academic Search

In this paper we describe an optimization procedure for planning the production of steel ingots in a steelmaking-continuous casting plant. The strict requirements of the production process defeated most of the earlier approaches to steelmaking-continuous casting production scheduling, mainly due to the lack of information in the optimization models. Our formulation of the problem is based on the alternative graph,

Dario Pacciarelli; Marco Pranzo

2004-01-01

352

MicroCast: Cooperative Video Streaming on Smartphones Lorenzo Keller  

E-print Network

MicroCast: Cooperative Video Streaming on Smartphones Lorenzo Keller School of I&C EPFL, Lausanne lends itself to cooperation. We propose a novel cooperative scheme, called Micro- Cast, for video, MicroDownload, that decides which parts of the video each phone should down- load from the server, based

Markopoulou, Athina

353

Rapid casting solutions: a review  

Microsoft Academic Search

Purpose – This paper seeks to review the industrial applications of state-of-the-art additive manufacturing (AM) techniques in metal casting technology. An extensive survey of concepts, techniques, approaches and suitability of various commercialised rapid casting (RC) solutions with traditional casting methods is presented. Design\\/methodology\\/approach – The tooling required for producing metal casting such as fabrication of patterns, cores and moulds with

Munish Chhabra; Rupinder Singh

2011-01-01

354

ZnO-based nonvolatile memory thin-film transistors with polymer dielectric\\/ferroelectric double gate insulators  

Microsoft Academic Search

The authors report on the fabrication of a top-gate ZnO thin-film transistor (TFT) with a polymer dielectric\\/ferroelectric double-layer gate insulator that was formed on patterned ZnO through a sequential spin-casting process of 450-nm-thick poly-4-vinylphenol (PVP) and 200-nm-thick poly(vinylidene fluoride\\/trifluoroethylene) [P(VDF\\/TrFE)]. Compared to the single P(VDF\\/TrFE) layer, double layer shows remarkably reduced leakage current with the aid of the PVP buffer.

Seok Hwan Noh; Wonjun Choi; Min Suk Oh; D. K. Hwang; Kimoon Lee; Seongil Im; Sungjin Jang; Eugene Kim

2007-01-01

355

Ohno continuous casting  

Microsoft Academic Search

Production of net-shape products directly from the liquid is an attractive manufacturing route for alloys that are difficult to process or that cannot be rolled, drawn, or extruded. Developed at the Chiba Institute of Technology in Japan, the Ohno Continuous Casting (OCC) approach not only provides significant cost savings, but also has the potential to create new products. OCC process

H. Soda; A. McLean; G. Motoyasu; A. Ohno

1995-01-01

356

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.

Scribner, Kenneth J. (Livermore, CA)

1985-01-01

357

Casting and Angling.  

ERIC Educational Resources Information Center

As part of a series of books and pamphlets on outdoor education, this manual consists of easy-to-follow instructions for fishing activities dealing with casting and angling. The manual may be used as a part of the regular physical education program in schools and colleges or as a club activity for the accomplished weekend fisherman or the…

Smith, Julian W.

358

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

359

Numerical study of porosity in titanium dental castings.  

PubMed

A commercial software package, MAGMASOFT (MAGMA Giessereitechnologie GmbH, Aachen, Germany), was used to study shrinkage and gas porosity in titanium dental castings. A geometrical model for two simplified tooth crowns connected by a connector bar was created. Both mold filling and solidification of this casting model were numerically simulated. Shrinkage porosity was quantitatively predicted by means of a built-in feeding criterion. The risk of gas pore formation was investigated using the numerical filling and solidification results. The results of the numerical simulations were compared with experiments, which were carried out on a centrifugal casting machine with an investment block mold. The block mold was made of SiO2 based slurry with a 1 mm thick Zr2 face coat to reduce metal-mold reactions. Both melting and casting were carried out under protective argon (40 kPa). The finished castings were sectioned and the shrinkage porosity determined. The experimentally determined shrinkage porosity coincided with the predicted numerical simulation results. No apparent gas porosity was found in these model castings. Several running and gating systems for the above model casting were numerically simulated. An optimized running and gating system design was then experimentally cast, which resulted in porosity-free castings. PMID:15348102

Wu, M; Sahm, P R; Augthun, M; Spiekermann, H; Schädlich-Stubenrauch, J

1999-09-01

360

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

361

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

362

Layer-by-Layer Fabrication of Oriented Porous Thin Films Based on Porphyrin-Containing Metal-Organic Frameworks  

E-print Network

of two thin films (DA-MOF and L2-MOF) of porphyrin-based MOFs on functionalized surfaces using a layer capable of yielding microporous MOFs containing accessible free-base porphyrins, it is noteworthy is demonstrated for both MOF films. The findings offer useful insights for subsequent fabrication of MOF-based

363

Optical multilayer films based on an amorphous fluoropolymer  

SciTech Connect

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

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

1996-01-01

364

ACCURATE QUANTIFICATION OF DRIED RESIDUE THIN FILMS USING X-RAY FLUORESCENCE  

SciTech Connect

An XRF specimen preparation method was developed to quantify the concentration of gallium in plutonium metal while minimizing the risk of contaminating the instrument with radioactive material. To ensure that homogeneous specimens are examined, plutonium is dissolved in dilute HCl and HNO{sub 3} prior to analysis. In the preliminary work here, non-radioactive aqueous gallium standards were prepared, and zinc was added as an internal standard to improve the accuracy and precision. Aliquots from these solutions were cast on Mylar XRF films and air dried prior to analysis. Two methods of casting the solutions were evaluated: (1) casting as a thin layer using a surfactant to wet the support film and (2) casting multiple small spots on the support film. Aqueous gallium standards were prepared and cast as dried residue specimens using each method. These specimens were then analyzed, and calibration curves were prepared. Highly linear calibrations were obtained for each preparation method when zinc was used as the internal standard (RMS values {le}1% of the standards concentration range in both cases). Based on this preliminary work, this dried residue process appears very promising for the accurate quantification of gallium in plutonium.

C. WORLEY; G. HAVRILLA

2000-09-01

365

The structure and magnetic properties of FePt based perpendicular exchange coupled composite films  

NASA Astrophysics Data System (ADS)

Two series of FePt/[Co/Pt]N (FPCP-N) and FePt/[Co/Ni]N (FPCN-N) exchange coupled composite (ECC) films were prepared and studied. Well isolated island-like grains with an average grain size of about 20nm are obtained. Both FePt hard layer and Co based soft multilayer are of perpendicular anisotropy. Large reduction of the switching field is observed when the Co based multilayer is deposited on the top of FePt films. When the thickness of Co based multilayers increase, thermal stability of the composites decreases slightly in both two series. Therefore, low switching field and high thermal stability are both obtained in these perpendicular ECC films.

Guo, H. H.; Liao, J. L.; Ma, B.; Zhang, Z. Z.; Jin, Q. Y.

366

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

2007-05-10

367

Optical waveguide spectrometer based on thin-film glass plates  

NASA Astrophysics Data System (ADS)

Commercially available thin-film glass plates have been successfully used for optical waveguide spectroscopy of chemical and biological films adsorbed upon the plates' surfaces. A 50-?m-thick glass plate was placed in contact with two parallel strips of silicone rubber supported on a slide glass. The plate area between the rubber strips served as the waveguiding region, eliminating the negative effect of the substrate on absorbance sensitivity. We coupled white light into the waveguide by focusing the light from a xenon lamp onto one end of a glass fiber and then inserting the other end into a glycerol drop overlaid upon the plate's surface. With a CCD detector, light at wavelengths as short as 360 nm was found to transmit out of the plate's end face. The propagation loss of the waveguide was measured to be <=1.2 dB/cm in the wavelength range 400-800 nm. A hemoglobin submonolayer equivalent to ~2% of a closely packed monolayer was detected with the sensor when the sensing path was 2 cm long.

Qi, Zhi-Mei; Matsuda, Naoki; Yoshida, Takamitsu; Asano, Hajime; Takatsu, Akiko; Kato, Kenji

2002-11-01

368

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

369

High piezoelectricity of Pb(Zr,Ti)O{sub 3}-based ternary compound thin films on silicon substrates  

SciTech Connect

Pb(Zr,Ti)O{sub 3} (PZT)-based ternary compound thin films, 0.06PMnN-0.94PZT(50/50) (PMnN-PZT), are deposited on Si-based heterostructures by rf magnetron sputtering system. The intrinsic PZT(50/50) thin films are also deposited on the same kind of substrates for comparison. The PMnN-PZT thin films show the similar polycrystalline structures as those of PZT with highly (111) oriented perovskite phase. The PMnN-PZT thin films show excellent piezoelectricity and ferroelectricity which are distinctly better than those of PZT thin films prepared with the same deposition conditions. Besides, the cantilevers of PMnN-PZT thin films on the heterostructure substrates also exhibit higher sensitivities than the PZT thin film cantilevers.

Zhang Tao; Zhang Shuyi; Chen Zhaojiang; Zhou Fengmei; Zhang Zhongning; Yang Yuetao [Lab of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210093 (China); Wasa, Kiyotaka [Lab of Modern Acoustics, Institute of Acoustics, Nanjing University, Nanjing 210093 (China); Department of Micro-engineering, Kyoto University, Kyoto 606-8501 (Japan)

2009-03-23

370

Slit-based supersonic microplasma jets: Scalable sources for nanostructured thin film deposition  

NASA Astrophysics Data System (ADS)

Slit-based, hollow cathode microplasma jets operating in under-expanded supersonic flow were investigated as spray deposition sources to realize nanostructured metal oxide thin films. Design of the slit cathode, its operation (e.g., IV characteristics, fluorescence imaging of supersonic flow shock structures, etc.), and companion CuO nanowire deposition experiments are discussed. Overall, this work demonstrates that slit-based, flow-through microplasmas are a promising way to scale up hollow cathode discharges for large area deposition of thin films at high pressures (>10 Torr).

Koh, T.; Chiles, I.; Gordon, M.

2013-10-01

371

Acid diffusion through polymer films  

NASA Astrophysics Data System (ADS)

In order to perform 0.2 micrometer processes, one needs to study the diffusion of photoacid generators within the photoresist system, since diffusion during post exposure bake time has an influence on the critical dimension (CD). We have developed a new method to study the diffusion of photoacid generators within a polymer film. This new method is based on monitoring the change of the fluorescence intensity of a pH- sensitive fluorescent dye caused by the reaction with photoacid. A simplified version of this experiment has been conducted by introducing acid vapor to quench the fluorescence intensity of this pH sensor. A thin polymer film is spin cast onto the sensor to create a barrier to the acid diffusion process. During the acid diffusion process, the fluorescence intensity of this pH sensor is measured in situ, using excitation and emission wavelengths at 466 nm and 516 nm, respectively. Fluoresceinamine, the pH sensitive fluorescent dye, is covalently bonded onto the treated quartz substrate to form a single dye layer. Poly(hydroxystyrene) (Mn equals 13k, Tg equals 180 degrees Celsius) in PGMEA (5% - 18% by weight) is spin cast onto this quartz substrate to form films with varying thickness. The soft bake time is 60 seconds at 90 degrees Celsius and a typical film has a thickness of 1.4 micrometers. Trifluoroacetic acid is introduced into a small chamber while the fluorescence from this quartz window is observed. Our study focuses on finding the diffusion constant of the vaporized acid (trifluoroacetic acid) in the poly(hydroxystyrene) polymer film. By applying the Fick's second law, (It - Io)/(I(infinity ) - Io) equals erfc [L/(Dt)1/2] is obtained. The change of fluorescence intensity with respect to the diffusion time is monitored. The above equation is used for the data analysis, where L represents the film thickness and t represents the average time for the acid to diffuse through the film. The diffusion constant is calculated to be at the order of 10-10 cm2/s to 10-12 cm2/s. All the experiments are conducted at room temperature and are valid only for acid vapor. With different film thickness, it was found that the acid diffuses through the film with a similar diffusion constant. The diffusion is faster with increased solvent residue in the film (controlled by spin coating speed). The theoretical computer modeling of the local acid concentration with respect to acid diffusion is also performed.

Zhang, P. Linda; Eckert, Andrew R.; Willson, C. Grant; Webber, Stephen E.; Byers, Jeffrey D.

1997-07-01

372

Finite element modeling of the deformation of magnetoelastic film  

SciTech Connect

Recently a new class of biocompatible elastic polymers loaded with small ferrous particles, a magnetoelastic polymer, has been developed. This engineered material is formed into a thin film using spin casting. An applied magnetic field will deform the film. The magnetic deformation of this film has many possible applications, particularly in microfluidic pumps and pressure regulators. In this paper a finite element method suitable for the transient simulation of arbitrarily shaped three-dimensional magnetoelastic polymers subjected to time-varying magnetic fields is developed. The approach is similar to that employed in finite elment magnetohydrodynamic simulations, the key difference is a more complex hyperelastic material model. In order to confirm the validity of the approach, finite element solutions for an axially symmetric thin film are compared to an analytical solution based on the membrane (infinitely thin) approximation. For this particular problem the two approaches give qualitatively similar results and converge as the film thickness approaches zero.

Barham, Matthew I. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551 (United States); White, Daniel A., E-mail: white37@llnl.go [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94551 (United States); Steigmann, David J. [6133 Etcheverry Hall, University of California, Berkeley, CA 94720 (United States)

2010-09-01

373

Comparison of diverse nanomaterial bioactivity profiles based on high-throughput screening (HTS) in ToxCast? (FutureToxII)  

EPA Science Inventory

Most nanomaterials (NMs) in commerce lack hazard data. Efficient NM testing requires suitable toxicity tests for prioritization of NMs to be tested. The EPA?s ToxCast program is screening NM bioactivities and ranking NMs by their bioactivities to inform targeted testing planning....

374

Material accountancy for metallic fuel pin casting  

Microsoft Academic Search

The operation of the Fuel Conditioning Facility (FCF) is based on the electrometallurgical processing of spent metallic reactor fuel. The pin casting operation, although only one of several operations in FCF, was the first to be on-line. As such, it has served to demonstrate the material accountancy system in many of its facets. This paper details, for the operation of

R. G. Bucher; Y. Orechwa; J. C. Beitel

1995-01-01

375

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

376

An Update on ToxCast?  

EPA Science Inventory

In its first phase, ToxCast? is profiling over 300 well-characterized chemicals (primarily pesticides) in over 400 HTS endpoints. These endpoints include biochemical assays of protein function, cell-based transcriptional reporter assays, multi-cell interaction assays, transcripto...

377

Numerical optimization of gating system parameters for a magnesium alloy casting with multiple performance characteristics  

Microsoft Academic Search

An optimization technique for design of gating system parameters of a cylindrical magnesium casting based on the Taguchi method with multiple performance characteristics was proposed in this paper. The various gating systems for a casting model of magnesium alloy were designed. Mold filling and solidification processes of the magnesium casting were simulated with the MAGMASOFT®. The simulation results indicated that

Zhizhong Sun; Henry Hu; Xiang Chen

2008-01-01

378

Caste development and reproduction: a genome-wide analysis of hallmarks of insect eusociality  

Microsoft Academic Search

The honey bee queen and worker castes are a model system for developmental plasticity. We used estab- lished expressed sequence tag information for a Gene Ontology based annotation of genes that are differen- tially expressed during caste development. Metabolic regulation emerged as a major theme, with a caste- specific difference in the expression of oxidoreduct- ases vs. hydrolases. Motif searches

A. S. Cristino; F. M. F. Nunes; C. H. Lobo; M. M. G. Bitondi; Z. L. P. Simões; L. da Fontoura Costa; H. M. G. Lattorff; R. F. A. Moritz; J. D. Evans; K. Hartfelder

2006-01-01

379

Effect of earthworm cast formation on the stabilization of organic matter in fine soil fractions  

Microsoft Academic Search

To study the effects of earthworm casting on organic matter dynamics, control soil and casts were added as a surface layer (Horizon I) to perspex cylinders containing a ‘base’ soil depleted in organic C (Horizon II). Three treatments with different Horizon I were used; a control containing uningested soil and oak litter (Quercus petraea (Mattuschka) Lieblein), cast derived from the

Michael McInerney; Declan J Little; Thomas Bolger

2001-01-01

380

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

381

Perception, 1998, volume 27, pages 591 -593 A moving cast shadow diminishes the Pulfrich phenomenon  

E-print Network

Perception, 1998, volume 27, pages 591 -593 A moving cast shadow diminishes the Pulfrich phenomenon, in revised form 20 April 1998 Abstract. It is demonstrated that the presence of a moving cast shadow [1996 Nature (London) 379 31] indicating that visible cast shadows can override monocularly based cues

Price, Theodore

382

Ant Stigmergy on the Grid: Optimizing the Cooling Process in Continuous Steel Casting  

E-print Network

Ant Stigmergy on the Grid: Optimizing the Cooling Process in Continuous Steel Casting Peter Korosec to the cooling process in the continuous casting of steel. The optimization task is to tune 18 coolant flows production is nowadays based on continuous casting. This is a complex met- allurgical process in which liquid

Silc, Jurij

383

Ultrathin Chitosan Films with Tailored Properties  

NASA Astrophysics Data System (ADS)

Chitosan is a biodegradable polysaccharide derived from seashell waste products. Though abundant, the industrial use of this polymer has up until recently been limited to water treatment products. The high water absorbency and biocompatibility of chitosan have enabled its use as a hydrogel in specialty applications such as wound dressings and drug delivery systems. The most convenient method of processing chitosan is solution casting to form films, since the polymer is soluble in weakly acidic solvents. Based on previous work with synthetic polymers, we have developed a protocol for preparing thin, uniform films of chitosan by spincoating from solution onto silicon substrates. Films with thicknesses between 30 and 600 nm (as measured by ellipsometry) and rms roughnesses of less than 1 nm (as measured by atomic force microscopy) were prepared. After preparation, these films quickly absorb water in the presence of high humidity. Heating of the films to high temperature causes large reductions in film thickness h and index of refraction n. After cooling the films to room temperature, h and n remain constant in the presence of high humidity. Using this simple procedure, we are able to produce films with tailored thickness, optical properties and water absorbency.

Murray, Chris; Stukalov, Oleg; Dutcher, John

2004-03-01

384

Preparation and electrochemical and electrocatalytic properties of nanocomposite multilayer film based on a Keggin-type phosphomolybdate.  

PubMed

An electrostatically self-assembled multilayer film has successfully been prepared on quartz or indium-tin-oxide substrates by alternating adsorption of a Keggin-type phosphomolybdate H3PMo12O40 (PMo12) and 1,10-diaminodecane (1,10-DAD). The formation of (PMo12/1,10-DAD), film was investigated by ultraviolet (UV) spectroscopy. The UV spectra showed that the deposition of the films was uniform and reproducible. The cyclic voltammetry on the PMo12-based multilayer film indicated that the PMo12 anions in the film undergo rapid four 2e(-)/2H+ redox processes, and electrocatalytically active towards the reduction of bromate. PMID:22413310

Gao, Li-Hua; Wang, Ke-Zhi; Wang, Li-Ying

2011-11-01

385

In situ electrodeposition of an asymmetric sol-gel membrane based on an octadecyltrimethoxysilane Langmuir film.  

PubMed

The unique properties of Langmuir film formation were utilized in assembling a thin skin of an asymmetric membrane. An octadecyltrimethoxysilane (ODTMS) Langmuir monolayer was formed at the air-water interface and served as the substrate for growing a bulky sol-gel polymer in situ. The latter was based on the electrochemical deposition of tetramethoxysilane dissolved in the water subphase by means of horizontal touch electrochemistry. The resultant asymmetric layer that consisted of a thin hydrophobic ODTMS Langmuir film connected to a bulk hydrophilic sol-gel network was studied in situ and ex situ by using various techniques, such as cyclic voltammetry, electrochemical impedance spectroscopy (EIS), scanning electron microscopy, transmission electron microscopy (TEM), and goniometry. We found that a porous hydrophilic film grew on top of a hydrophobic layer as was evident from TEM, contact angle, and EIS analyses. The film thickness and film permeability could be controlled by changing the deposition conditions such as the potential window applied and its duration. Hence, this method offers an alternative approach for assembling asymmetric films for various applications. PMID:25111107

Hitrik, Maria; Lev, Ovadia; Mandler, Daniel

2014-09-15

386

Stability of methylcellulose-based films after being subjected to different conservation and processing temperatures.  

PubMed

Methylcellulose films with and without sorbitol addition were developed. The major objective of this study was to attempt insights into the stability of the methylcellulose-based film properties after having been subjected to freezing, storage or a combination of both procedures. The importance of the sorbitol concentration and process temperature was also to be elucidated. As-prepared film solubility decreased at 100 °C, as a result of the methylcellulose thermogelation property when the samples were exposed to high temperatures. By analyzing the film pattern behavior and its properties 0.25% w/v sorbitol concentration turned out to be an inflexion point. The moisture content as well as the mechanical and thermal properties made this fact evident. Moreover the elastic modulus (Ec) and glass transition temperature (Tg) did not undergo significant changes for higher plasticizer concentrations. The methylcellulose film properties remained more stable in the presence of sorbitol, which would act as a protective agent due to its hydrogen bonding capacity. This stability is crucial for film and coating applications in the food industry. PMID:23623115

Tavera Quiroz, M J; Lecot, J; Bertola, N; Pinotti, A

2013-07-01

387

An adaptive pattern recognition and detection technique for target image of continuous casting with length cutting  

Microsoft Academic Search

In production process of steel making and continuous casting, on-line length measurement and fixed length of continuous casting slab are very important. Starting from increasing the yield of length cutting for continuous casting products, on the base of cutting measurement about non-contact automatic cutting length. Such problems were introduced as abrasion and slippage, which existed in measure-roller of continuous casting

Liu Xiaoyue; Yan Jing

2009-01-01

388

Characterization of centrifugal cast functionally graded aluminum-silicon carbide metal matrix composites  

Microsoft Academic Search

The present investigation is on characterization of functionally graded composites based on 356 cast and 2124 wrought aluminum alloys reinforced with SiC particles of 23?m average particle size processed by liquid metal stir casting followed by horizontal centrifugal casting. A maximum of 45 and 40% SiC particles are obtained at the outer periphery of the Al(356)-SiC and Al(2124)-SiC FGMMC casting

T. P. D. Rajan; R. M. Pillai; B. C. Pai

2010-01-01

389

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

390

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

391

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

392

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

393

Oxygen-scavenging coatings and films based on lignosulfonates and laccase.  

PubMed

Laccase and lignosulfonates were included in coating colors and embedded in latex-based or starch-based films and coatings on foil or board. After 6 days at 23 °C and 100% relative humidity, the oxygen content in airtight chambers decreased from 1.0% (synthetic gas consisting of 99% N(2) and 1% O(2)) to 0.3% in the presence of board coated with lignosulfonate and laccase, while the oxygen content remained unchanged in control experiments without enzyme. The water stability of lignosulfonate-containing latex-based coatings and starch-based films was improved after laccase-catalyzed oxidation of lignosulfonates, which indicates polymerization to products with lower solubility in water. Furthermore, the E' modulus of starch-based films increased with 30%, which indicates laccase-catalyzed polymerization of lignosulfonates resulting in increased stiffness of the film. The results suggest that laccases and lignosulfonates can be used as an oxygen-scavenging system in active packaging and that enzyme-catalyzed polymerization of lignosulfonates contributes to improved water stability and mechanical properties. PMID:22721759

Johansson, Kristin; Winestrand, Sandra; Johansson, Caisa; Järnström, Lars; Jönsson, Leif J

2012-09-15

394

USGS CoreCast  

NSDL National Science Digital Library

Just about everyone seems to be creating a podcast these days, and a number of government agencies have entered the fray as of late. The United States Geological Survey recently decided to hang out their own podcast shingle, and the results of their labors can be explored here. The site states that their "CoreCast" is "natural science from the inside out", which seems like an appropriate label. The podcasts range in length from two to fifteen minutes, and they cover topics such as polar bear research, sex-changing fish, and climate change. One podcast that shouldn't be overlooked is "This Episode of CoreCast is Highly Questionable". In a mere three minutes, host Scott Horvath responds to a number of questions in an engaging fashion. After listening to an episode or two, visitors will probably want to sign up to receive email updates about new episodes.

395

Volume MLS ray casting.  

PubMed

The method of Moving Least Squares (MLS) is a popular framework for reconstructing continuous functions from scattered data due to its rich mathematical properties and well-understood theoretical foundations. This paper applies MLS to volume rendering, providing a unified mathematical framework for ray casting of scalar data stored over regular as well as irregular grids. We use the MLS reconstruction to render smooth isosurfaces and to compute accurate derivatives for high-quality shading effects. We also present a novel, adaptive preintegration scheme to improve the efficiency of the ray casting algorithm by reducing the overall number of function evaluations, and an efficient implementation of our framework exploiting modern graphics hardware. The resulting system enables high-quality volume integration and shaded isosurface rendering for regular and irregular volume data. PMID:18988986

Ledergerber, Christian; Guennebaud, Gaël; Meyer, Miriah; Bächer, Moritz; Pfister, Hanspeter

2008-01-01

396

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

397

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

398

Correlation between sputtering parameters and composition of SmCo-based films for microelectromechanical system applications  

NASA Astrophysics Data System (ADS)

About 3.0 ?m thick SmCo-based films with additives of Fe, Cu, and Zr were deposited on Si substrates. Based on a developed semiempirical theoretical model, the dependence of the film composition on the sputtering parameters was discussed. The experimental results show that the Sm concentration increases with decreasing sputtering power or increasing Ar gas pressure, which are in good agreement with the calculated results when the preferential sputtering effect is disregarded. The effect of the sputtering parameters on the film composition provides an opportunity for the same composite target to fabricate films with Sm concentration varying from 13.8 to 17.3 at. %, which is reasonable for the permanent magnetic phase transformation (Sm2Co17?SmCo7?SmCo5). Furthermore, the observed TbCu7-type film shows a better crystal texture with a low remanence ratio for the hysteresis loops measured out plane to in plane of 0.08.

Peng, Long; Zhang, Huaiwu; Yang, Qinghui; Li, Yuanxun; Song, Yuanqiang; Shen, Jian

2009-03-01

399

Hydrogen Bonded Multilayer Films Based on Poly(2-oxazoline)s and Tannic Acid.  

PubMed

In recent years, the layer-by-layer (LbL) assembly based on hydrogen bonding interactions is gaining popularity for the preparation of thin film coatings, especially for biomedical purposes, based on the use of neutral, non-toxic building blocks. The use of tannic acid (TA) as hydrogen bonding donor is especially interesting as it results in LbL films that are stable under physiological conditions. In this work, investigations on the LbL thin film preparation of TA with poly(2-oxazoline)s with varying hydrophilicity, namely poly(2-methyl-2-oxazoline) (PMeOx), poly(2-ethyl-2-oxazoline) (PEtOx) and poly(2-n-propyl-2-oxazoline) (PnPropOx), are reported. The LbL assembly process is investigated by quartz crystal microbalance and UV-vis spectroscopy revealing linear growth of the film thickness. Furthermore, isothermal titration calorimetry demonstrates the LbL assembly of TA, and PMeOx is found to be mostly enthalpy driven while the LbL assembly of TA with PEtOx and PnPropOx is mostly entropy driven. Finally, scanning electron microscopy and ellipsometry demonstrate the formation of smooth thin films for LbL assembly of TA with all three polymers. Such poly(2-oxazoline) coatings have high potential for use as anti-biofouling coatings. PMID:25274164

Sundaramurthy, Anandhakumar; Vergaelen, Maarten; Maji, Samarendra; Auzély-Velty, Rachel; Zhang, Zhiyue; De Geest, Bruno G; Hoogenboom, Richard

2014-12-01

400

Growth, structural, and electrical characterizations of organic thin films on Si-based substrates  

NASA Astrophysics Data System (ADS)

This PhD thesis focuses on the investigation of growth, structural and electrical properties of organic semiconductor thin films on Si-based substrates. With a novel design for an home-made Knudsen cell, growth of layer-by-layer organic thin films (tetracene and pentacene) has been successfully achieved under proper kinetic growth conditions using an ultra-high-vacuum organic molecular beam deposition (UHV-OMBD) system. Morphological studies and modem synchrotron radiation experimental results have shown that the growth is in a 2D+3D mode driven by the molecular structure conformation processes near the interfaces. Using the classic nucleation theory, the molecular nucleation behaviors (condensation, critical nucleus size, diffusion, activation energy) on Si-based surfaces have been analyzed to be kinetically diffusion-limited. In addition, using the dynamic scaling theory, the anomalous interface roughening processes of tetracene and pentacene thin film growth have been discovered and growth parameters (e.g. roughness, dynamic, and growth exponents) extracted. A new view of "fractal-mound" -on- "fractal-mound" growth mode has been proposed to explain the exotic roughening behavior of organic thin film growth. Finally, the electrical transportation dependence on activation layer thickness in organic thin film transistors has been studied.

Shi, Jun

401

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

NASA Astrophysics Data System (ADS)

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

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

2011-04-01

402

Highlights on photocathodes based on thin films prepared by pulsed laser deposition  

NASA Astrophysics Data System (ADS)

We review the current status of metallic photocathodes based on thin films prepared by pulsed laser deposition (PLD) and we explore ways to improve the performance of these devices. PLD seems to be a very efficient and suitable technique for producing adherent and uniform thin films. Time-resolved mass spectrometric investigations definitively suggest that the deposition of high-purity metallic thin films should be carried out in ultrahigh vacuum systems and after a deep and careful laser cleaning of the target surface. Moreover, the laser cleaning of the target surface is highly recommended not only to remove the first contaminated layers but also to improve the quality of the vacuum by reducing the partial pressure of reactive chemical species as H2O, H2, and O2 molecules. The challenge to realize high-purity Mg and Y thin films is very interesting for the photocathode R&D due to the good photoemission properties of these metals. Photocathodes based on Mg and Y thin films have been characterized by scanning electron microscopy and x-ray diffraction techniques to derive the morphological and structural features, respectively. They were also tested in a photodiode cell to deduce the photoelectron properties. The quantum efficiency of such photocathodes was systematically improved by in situ laser cleaning treatments of the surface in order to remove the contaminated layers reaching, in this way, the quantum efficiency of the corresponding bulk materials.

Lorusso, A.; Gontad, F.; Perrone, A.; Stankova, N.

2011-09-01

403

Correlation between sputtering parameters and composition of SmCo-based films for microelectromechanical system applications  

SciTech Connect

About 3.0 {mu}m thick SmCo-based films with additives of Fe, Cu, and Zr were deposited on Si substrates. Based on a developed semiempirical theoretical model, the dependence of the film composition on the sputtering parameters was discussed. The experimental results show that the Sm concentration increases with decreasing sputtering power or increasing Ar gas pressure, which are in good agreement with the calculated results when the preferential sputtering effect is disregarded. The effect of the sputtering parameters on the film composition provides an opportunity for the same composite target to fabricate films with Sm concentration varying from 13.8 to 17.3 at. %, which is reasonable for the permanent magnetic phase transformation (Sm{sub 2}Co{sub 17}{yields}SmCo{sub 7}{yields}SmCo{sub 5}). Furthermore, the observed TbCu{sub 7}-type film shows a better crystal texture with a low remanence ratio for the hysteresis loops measured out plane to in plane of 0.08.

Peng Long; Zhang Huaiwu; Yang Qinghui; Li Yuanxun; Song Yuanqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Shen Jian [Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716 (United States)

2009-03-15

404

Water-soluble single-walled carbon nanotubes films: Preparation, characterization and applications as electrochemical sensing films  

Microsoft Academic Search

Water-soluble single-walled carbon nanotubes (SWNTs) were prepared via noncovalent functionalization by Congo red through a physical grinding treatment. Based on the unique property of strong rebundling when dried, water-soluble SWNTs were firmly immobilized on the surface of a glassy carbon electrode by a simple casting method. The prepared films were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and

Chengguo Hu; Xiaoxia Chen; Shengshui Hu

2006-01-01

405

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

406

Charge carrier trapping in highly-ordered lyotropic chromonic liquid crystal films based on ionic perylene diimide derivatives  

NASA Astrophysics Data System (ADS)

Charge carrier trapping in thin films of lyotropic chromonic liquid crystals (LCLCs) based on ionic perylene diimide derivative and in chemically-similar neutral N,N'-dipentyl-3,4,9,10-perylene-dicarboximide (PTCDI-C5) films is investigated by thermally-stimulated luminescence (TSL) technique. The LCLC films comprise elongated molecular aggregates featuring a long-range orientational order. The obtained results provide direct evidence for the improved energetic ordering (smaller effective energetic disorder) in aggregated LCLC films as compared to conventional PTCDI-C5 films. The width of the density-of-state distribution of 0.09 eV and 0.13 eV was estimated for the LCLC and PTCDI-C5 films, respectively. Relatively small effective energetic disorder in LCLC films is ascribed to formation of macroscopically larger LCLC aggregates.

Soroka, Pavlo V.; Vakhnin, Alexander Yu.; Skryshevskiy, Yuriy A.; Boiko, Oleksandr P.; Anisimov, Maksim I.; Slominskiy, Yuriy L.; Nazarenko, Vassili G.; Genoe, Jan; Kadashchuk, Andrey

2014-12-01

407

Swift heavy ion induced surface modification for tailoring coercivity in Fe-Ni based amorphous thin films  

SciTech Connect

Fe-Ni based amorphous thin films were prepared by thermal evaporation. These films were irradiated by 108 MeV Ag{sup 8+} ions at room temperature with fluences ranging from 1x10{sup 12} to 3x10{sup 13} ions/cm{sup 2} using a 15 UD Pelletron accelerator. Glancing angle x-ray diffraction studies showed that the irradiated films retain their amorphous nature. The topographical evolution of the films under swift heavy ion (SHI) bombardment was probed using atomic force microscope and it was noticed that surface roughening was taking place with ion beam irradiation. Magnetic measurements using a vibrating sample magnetometer showed that the coercivity of the films increases with an increase in the ion fluence. The observed coercivity changes are correlated with topographical evolution of the films under SHI irradiation. The ability to modify the magnetic properties via SHI irradiation could be utilized for applications in thin film magnetism.

Thomas, Senoy; Thomas, Hysen; Anantharaman, M. R. [Department of Physics, Cochin University of Science and Technology, Cochin 682022 (India); Avasthi, D. K.; Tripathi, A. [Materials Science Division, Inter University Accelerator Centre, New Delhi 110067 (India); Ramanujan, R. V. [School of Materials Science and Engineering, Nanyang Technological University, Nanyang Avenue, Singapore 639798 (Singapore)

2009-02-01

408

Dielectric properties of film materials based on polyethylene terephthalate and polycarbonate with ferroelectric inclusions  

NASA Astrophysics Data System (ADS)

The dielectric properties of film materials based on polyethylene terephthalate and polycarbonate with inclusions of triglycine sulfate (TGS) and TGS with admixture of L, ?-alanine (ATGS) have been studied. An increase in the temperature of the phase transition in these materials as compared to in bulk TGS and ATGS has been revealed.

Golitsyna, O. M.; Drozhdin, S. N.

2012-08-01

409

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

410

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

411

Stability and oxidation of the sandwich type gas sensors based on thin metal films  

Microsoft Academic Search

The stability of the properties is investigated in the new family of the solid-state gas sensors based on various thin metal films (Pt, Au, Ni, Mo) with the modifying top layer of tin oxide. The resistance response to exposure to gas is demonstrated being stable within certain interval of temperatures. The limits of the interval depend on the metal selected

A. Galdikas; S. Ka?iulis; G. Mattogno; A. Mironas; A. Šetkus

1998-01-01

412

Effects of nanoclay type on the physical and antimicrobial properties of PVOH-based nanocomposite films  

Technology Transfer Automated Retrieval System (TEKTRAN)

Polyvinyl alcohols-based nanocomposite films were fabricated with four types of montmorillonite (MMT) nanoclay, including 18-amino stearic acid (I.24TL), methyl, bis hydroxyethyl, octadecyl ammonium (I.34TCN), di-methyl, di-hydrogenated tallow ammonium/siloxane (I.44PSS) organically modified MMT, an...

413

Low-loss plasmonic metamaterial based on epitaxial gold monocrystal film  

E-print Network

Low-loss plasmonic metamaterial based on epitaxial gold monocrystal film V. A. Fedotov,1,2,* T Centre for Photonic Metamaterials, University of Southampton, SO17 1BJ, UK 3 School of Electronics high-finesse plasmonic metamaterial with strong resonant response in the near-IR spectral range

Zheludev, Nikolay

414

Enhanced frequency response of a highly transparent PVDF-graphene based thin film acoustic actuator.  

PubMed

A high-performance polyvinylidene fluoride (PVDF) based thin film acoustic actuator with chemical vapor deposition (CVD) graphene electrodes was successfully fabricated. Importantly, it showed 60, 19, and 22% enhancement in the bass, middle and treble frequency response, respectively. PMID:24136447

Lee, James S; Shin, Keun-Young; Kim, Chanhoi; Jang, Jyongsik

2013-12-01

415

Composite edible films based on hydroxypropyl methyl cellulose reinforced with microcrystalline cellulose nanoparticles  

Technology Transfer Automated Retrieval System (TEKTRAN)

It has been stated that hydroxypropyl methyl cellulose (HPMC) based films have promising applications in the food industry because of their environmental appeal, low cost, flexibility and transparency. Nevertheless, their mechanical and moisture barrier properties should be improved. The aim of th...

416

Characteristics of Graphitic Films for Carbon Based Magnetism and Electronics.  

E-print Network

??This dissertation concentrates on the characteristics of graphene, a single layer of graphite, defined as two-dimensional material for carbon based magnetism and electronics. Carbon materials,… (more)

Hong, Jeongmin

2009-01-01

417

High-frequency surface acoustic wave device based on thin-film piezoelectric interdigital transducers  

Microsoft Academic Search

Using high-quality epitaxial c-axis Pb(Zr0.2Ti0.8)O3 films grown by off-axis magnetron sputtering onto metallic (001) Nb-doped SrTiO3 substrates, a nonconventional thin-film surface acoustic wave device based on periodic piezoelectric transducers was realized. The piezoelectric transducers consist of a series of ferroelectric domains with alternating polarization states. The artificial modification of the ferroelectric domain structure is performed by using an atomic force

A. K. Sarin Kumar; P. Paruch; J.-M. Triscone; W. Daniau; S. Ballandras; L. Pellegrino; D. Marré; T. Tybell

2004-01-01

418

Nano particle porous alumina based thin film parallel plate capacitive humidity sensor  

NASA Astrophysics Data System (ADS)

A Relative humidity sensor was fabricated based on porous thin film of ?-Al2O3 formed between the parallel Pd/Ag electrodes working on capacitive technique. The film was fabricated by dip coating of sol solution obtained from the sol-gel method. The electrical parameters of the sensor have been determined by Agilent 4294A impedance analyzer. The sensor so obtained is found to be sensitive in 10 to 90% RH. The response time of the sensor is very low around 24 seconds and recovery time 40 seconds.

Kumar, Shailesh

2014-04-01

419

Study of As50Se50 Thin Film Dissolution Kinetics in Amine based Solutions  

NASA Astrophysics Data System (ADS)

Chalcogenide glass thin films are suitable materials for micro optical elements fabrication due to their convenient physical and chemical properties. They are generally photosensitive and thus can be selectively etched. Therefore they can be exploited as photoresists in photolithography. In this paper we deal with the study of As50Se50 thin films dissolution kinetics in EDA based solutions. The detailed evolution of the etching curves is discussed and the dependences of the average etching rate on the composition and temperature of the etching bath are described.

Pálka, K.; Vl?ek, M.; Kovalskiy, A.

420

Across-plane thermal characterization of films based on amplitude-frequency profile in photothermal technique  

SciTech Connect

This work develops an amplitude method for the photothermal (PT) technique to analyze the amplitude of the thermal radiation signal from the surface of a multilayered film sample. The thermal conductivity of any individual layer in the sample can be thereby determined. Chemical vapor deposited SiC film samples (sample 1 to 3: 2.5 to 3.5 ?m thickness) with different ratios of Si to C and thermally oxidized SiO{sub 2} film (500 nm thickness) on silicon substrates are studied using the amplitude method. The determined thermal conductivity based on the amplitude method is 3.58, 3.59, and 2.59 W/m?K for sample 1 to 3 with ±10% uncertainty. These results are verified by the phase shift method, and sound agreement is obtained. The measured thermal conductivity (k) of SiC is much lower than the value of bulk SiC. The large k reduction is caused by the structure difference revealed by Raman spectroscopy. For the SiO{sub 2} film, the thermal conductivity is measured to be 1.68 ± 0.17 W/m?K, a little higher than that obtained by the phase shift method: 1.31 ± 0.06 W/m?K. Sensitivity analysis of thermal conductivity and interfacial resistance is conducted for the amplitude method. Its weak-sensitivity to the thermal contact resistance, enables the amplitude method to determine the thermal conductivity of a film sample with little effect from the interface thermal resistance between the film and substrate. The normalized amplitude ratio at a high frequency to that at a low frequency provides a reliable way to evaluate the effusivity ratio of the film to that of the substrate.

Xu, Shen; Wang, Xinwei, E-mail: xwang3@iastate.edu [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

2014-10-15

421

Across-plane thermal characterization of films based on amplitude-frequency profile in photothermal technique  

NASA Astrophysics Data System (ADS)

This work develops an amplitude method for the photothermal (PT) technique to analyze the amplitude of the thermal radiation signal from the surface of a multilayered film sample. The thermal conductivity of any individual layer in the sample can be thereby determined. Chemical vapor deposited SiC film samples (sample 1 to 3: 2.5 to 3.5 ?m thickness) with different ratios of Si to C and thermally oxidized SiO2 film (500 nm thickness) on silicon substrates are studied using the amplitude method. The determined thermal conductivity based on the amplitude method is 3.58, 3.59, and 2.59 W/m?K for sample 1 to 3 with ±10% uncertainty. These results are verified by the phase shift method, and sound agreement is obtained. The measured thermal conductivity (k) of SiC is much lower than the value of bulk SiC. The large k reduction is caused by the structure difference revealed by Raman spectroscopy. For the SiO2 film, the thermal conductivity is measured to be 1.68 ± 0.17 W/m?K, a little higher than that obtained by the phase shift method: 1.31 ± 0.06 W/m?K. Sensitivity analysis of thermal conductivity and interfacial resistance is conducted for the amplitude method. Its weak-sensitivity to the thermal contact resistance, enables the amplitude method to determine the thermal conductivity of a film sample with little effect from the interface thermal resistance between the film and substrate. The normalized amplitude ratio at a high frequency to that at a low frequency provides a reliable way to evaluate the effusivity ratio of the film to that of the substrate.

Xu, Shen; Wang, Xinwei

2014-10-01

422

High Temperature - Thin Film Strain Gages Based on Alloys of Indium Tin Oxide  

NASA Technical Reports Server (NTRS)

A stable, high temperature strain gage based on reactively sputtered indium tin oxide (ITO) was demonstrated at temperatures up to 1050 C. These strain sensors exhibited relatively large, negative gage factors at room temperature and their piezoresistive response was both linear and reproducible when strained up to 700 micro-in/in. When cycled between compression and tension, these sensors also showed very little hysteresis, indicating excellent mechanical stability. Thin film strain gages based on selected ITO alloys withstood more than 50,000 strain cycles of +/- 500 micro-in/in during 180 hours of testing in air at 1000 C, with minimal drift at temperature. Drift rates as low as 0.0009%/hr at 1000 C were observed for ITO films that were annealed in nitrogen at 700 C prior to strain testing. These results compare favorably with state of the art 10 micro-m thick PdCr films deposited by NASA, where drift rates of 0.047%/hr at 1050 C were observed. Nitrogen annealing not only produced the lowest drift rates to date, but also produce the largest dynamic gage factors (G = 23.5). These wide bandgap, semiconductor strain sensors also exhibited moderately low temperature coefficients of resistance (TCR) at temperatures up to 1100 C, when tested in a nitrogen ambient. A TCR of +230 ppm/C over the temperature range 200 C < T < 500 C and a TCR of -469 ppm/C over the temperature range 600 C < T < 1100 C was observed for the films tested in nitrogen. However, the resistivity behavior changed considerably when the same films were tested in oxygen ambients. A TCR of -1560 ppm/C was obtained over the temperature range of 200 C < T < 1100 C. When similar films were protected with an overcoat or when ITO films were prepared with higher oxygen contents in the plasma, two distinct TCR's were observed. At T < 800 C, a linear TCR of -210 ppm/C was observed and at T > 800 C, a linear TCR of -2170 DDm/C was observed. The combination of a moderately low TCR and a relatively large gage factor make these semiconducting oxide films promising candidates for the active strain elements in high temperature thin film strain gages, particularly in applications where static strain measurement is desired.

Gregory, Otto J.; Cooke, James D.; Bienkiewicz, Joseph M.

1998-01-01

423

Characterization of peanut-soybean films for food packaging applications  

E-print Network

Edible films made from peanut and soybean were developed using casting and single-screw extrusion methods. The effect of time, formulation and processing method on the rheological, barrier and physical properties of the experimental films were...

Tellez Garay, Angela Maria

2012-06-07

424

Electronic properties of phenylated ligand-capped nanoparticle films  

E-print Network

An investigation was carried out of the electronic characteristics of drop-cast films comprised of phenylated ligand-capped gold nanoparticles. In homoligand-type films, the dominant mechanism of charge transfer was expected ...

Schilling, Thomas C

2006-01-01

425

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

426

Deoxyribonucleic acid-based hybrid thin films for potential application as high energy density capacitors  

NASA Astrophysics Data System (ADS)

Deoxyribonucleic acid (DNA) based hybrid films incorporating sol-gel-derived ceramics have shown strong promise as insulating dielectrics for high voltage capacitor applications. Our studies of DNA-CTMA (cetyltrimethylammonium) complex/sol-gel ceramic hybrid thin film devices have demonstrated reproducibility and stability in temperature- and frequency-dependent dielectric properties with dielectric constant k ˜ 5.0 (1 kHz), as well as reliability in DC voltage breakdown measurements, attaining values consistently in the range of 300-350 V/?m. The electrical/dielectric characteristics of DNA-CTMA films with sol-gel-derived ceramics were examined to determine the critical energy storage parameters such as voltage breakdown and dielectric constant.

Joyce, Donna M.; Venkat, Narayanan; Ouchen, Fahima; Singh, Kristi M.; Smith, Steven R.; Grabowski, Christopher A.; Terry Murray, P.; Grote, James G.

2014-03-01

427

K-Band Reflectarray Antenna Based on Ferroelectric Thin Films: What Have We Learned so Far  

NASA Technical Reports Server (NTRS)

The Applied RF Technology Branch of the NASA Glenn Research Center, Cleveland, Ohio, has an on-going effort in the area of thin film ferroelectric technology for microwave applications. Particular attention has been given to developing ferroelectric phase shifters for the implementation and experimental demonstration of an electronically steerable reflectarray antenna. In the process of optimizing these material to fit the implementation requirements of the aforementioned antenna, we have accumulated a great deal of information and knowledge in areas such as the effect of the composition of the ferroelectric thin films on phase shifter performance, self assembled monolayers (SAMs) in the metallic/ferroelectric interface and their impact on phase shifter performance, correlation between microstructure and microwave properties, and the effect of selective etching on the overall performance of a thin film-ferroelectric based microwave component, amongst others. We will discuss these issues and will provide an up-dade of the current development status of the reflect-array antenna.

Miranda, Felix A.; Romanofsky, Robert; Mueller, Carl H.; VanKeuls, Fred

2002-01-01

428

Semiconducting properties of amorphous GaZnSnO thin film based on combinatorial electronic structures  

SciTech Connect

Semiconducting properties and electronic structures of amorphous GaZnSnO (GZTO) thin films are investigated with respect to metal cationic composition. An increase of the cationic Sn ratio resulted in an increase of the carrier concentration and a decrease of the mobility of the films. Combinatorial analysis revealed that the electrical characteristics of GZTO films are strongly correlated to changes in electronic structure. The increase in carrier concentration is related to the generation of vacancies by the changes of oxygen coordination around the cationic metal and the shallow band edge state below the conduction band. On the other hand, the decrease of mobility can be explained by the deep band edge state, and the difference between the experimental conduction band and simulated conduction band by the combinatorial electronic structure based on the chemical composition.

Kim, B. K. [Department of Physics, Dankook University, Cheonan 300-714 (Korea, Republic of); Park, J. S. [Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, D. H. [Functional Coatings Research Group, Korea Institute of Materials Science, Changwon, Gyeongnam 641-831 (Korea, Republic of); Chung, K. B., E-mail: kbchung@dongguk.edu [Division of Physics and Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of)

2014-05-05

429

Fiber optic magnetic field sensor based on domain wall motion in garnet film waveguides  

NASA Astrophysics Data System (ADS)

A novel fiber optic magnetometer based on the Faraday effect in a magnetic garnet thin-film ridged waveguide is described. The single-mode film has planar magnetization aligned parallel and antiparallel to the light propagation direction by a gradient bias field, and a single domain wall crosses the light path. The motion of this wall in response to an applied field changes the Faraday rotation in the film. Operation of this field or current sensor in both the transmission mode and the single fiber reflection mode has been demonstrated. Optical output varying linearly with ac or dc fields up to 15 Oe, with a minimum detectable field of 0.05 Oe, has been observed. This domain wall motion scheme in a zero birefringence waveguide can also be used in a polarization controller.

Wolfe, R.; Lieberman, R. A.

1991-04-01

430

Third generation biosensing matrix based on Fe-implanted ZnO thin film  

NASA Astrophysics Data System (ADS)

Third generation biosensor based on Fe-implanted ZnO (Fe-ZnO) thin film has been demonstrated. Implantation of Fe in rf-sputtered ZnO thin film introduces redox center along with shallow donor level and thereby enhance its electron transfer property. Glucose oxidase (GOx), chosen as model enzyme, has been immobilized on the surface of the matrix. Cyclic voltammetry and photometric assay show that the prepared bioelectrode, GOx/Fe-ZnO/ITO/Glass is sensitive to the glucose concentration with enhanced response of 0.326 ?A mM-1 cm-2 and low Km of 2.76 mM. The results show promising application of Fe-implanted ZnO thin film as an attractive matrix for third generation biosensing.

Saha, Shibu; Gupta, Vinay; Sreenivas, K.; Tan, H. H.; Jagadish, C.

2010-09-01

431

Impermeable barrier films and protective coatings based on reduced graphene oxide  

NASA Astrophysics Data System (ADS)

Flexible barrier films preventing permeation of gases and moistures are important for many industries ranging from food to medical and from chemical to electronic. From this perspective, graphene has recently attracted particular interest because its defect-free monolayers are impermeable to all atoms and molecules. However, it has been proved to be challenging to develop large-area defectless graphene films suitable for industrial use. Here we report barrier properties of multilayer graphitic films made by gentle chemical reduction of graphene oxide laminates with hydroiodic and ascorbic acids. They are found to be highly impermeable to all gases, liquids and aggressive chemicals including, for example, hydrofluoric acid. The exceptional barrier properties are attributed to a high degree of graphitization of the laminates and little structural damage during reduction. This work indicates a close prospect of graphene-based flexible and inert barriers and protective coatings, which can be of interest for numerous applications.

Su, Y.; Kravets, V. G.; Wong, S. L.; Waters, J.; Geim, A. K.; Nair, R. R.

2014-09-01

432

Electric bistability in pentacene film-based transistor embedding gold nanoparticles.  

PubMed

Pentacene films were deposited on a silica surface decorated with gold nanoparticles (Au-NPs). The crystallinity and packing orientation of the film are critically dependent on the surface properties of the nanoparticles, which can be tuned by a self-assembled monolayer (SAM) of organic thiolate on the nanoparticles. High-performance field-effect transistors based on the Au-NPs-embedded pentacene films can be prepared if the nanoparticles are made "hydrophobic" as well as "oleophobic" by appropriate SAMs. Electrical bistability was observed in these devices, with a memory window that depends on the size and surface modification of the Au-NPs. The structural characterization and electronic characteristics of the devices will be detailed. PMID:19655797

Tseng, Chiao-Wei; Tao, Yu-Tai

2009-09-01

433

Bionanocomposite films based on plasticized PLA-PHB/cellulose nanocrystal blends.  

PubMed

Optically transparent plasticized poly(lactic acid) (PLA) based bionanocomposite films intended for food packaging were prepared by melt blending. Materials were plasticized with 15wt% of acetyl(tributyl citrate) (ATBC) to improve the material processability and to obtain flexibile films. Poly(hydroxybutyrate) (PHB) was used to increase PLA crystallinity. The thermal stability of the PLA-PHB blends was improved by the addition of 5wt% of cellulose nanocrystals (CNC) or modified cellulose nanocrystals (CNCs) synthesized from microcrystalline cellulose. The combination of ATBC and cellulose nanocrystals, mainly the better dispersed CNCs, improved the interaction between PLA and PHB. Thus, an improvement on the oxygen barrier and stretchability was achieved in PLA-PHB-CNCs-ATBC which also displayed somewhat UV light blocking effect. All bionanocomposite films presented appropriate disintegration in compost suggesting their possible applications as biodegradable packaging materials. PMID:25659698

Arrieta, M P; Fortunati, E; Dominici, F; López, J; Kenny, J M

2015-05-01

434

Fast Docking on Graphics Processing Units via Ray-Casting  

E-print Network

Docking Approach using Ray Casting (DARC) is structure-based computational method for carrying out virtual screening by docking small-molecules into protein surface pockets. In a complementary study we find that DARC can be used to identify known...

Khar, Karen R.; Goldschmidt, Lukasz; Karanicolas, John

2013-08-16

435

Constructivist Learning of Anatomy: Gaining Knowledge by Creating Anatomical Casts  

NSDL National Science Digital Library

This article describes a method to promote inquiry based learning in the anatomy curriculum. The article describes a method requiring students to build casts of the bronchial tree and coronary arteries while faculty asked leading questions related to the material.

Heidi L. Lujan (Wayne State Univ Sch Med Dept of Physiology); Stephen E DiCarlo (Northeastern Ohio University College of Medicine Department of Physiology)

2011-03-01

436

Sputtered silver films to improve chromium carbide based solid lubricant coatings for use to 900 C  

NASA Technical Reports Server (NTRS)

Thin silver films, 250 to 3500 A thick, were sputtered onto PS200, a plasma sprayed, chromium carbide based solid lubricant coating, to reduce run-in wear and improve tribological properties. The coating contains bonded chromium carbide as the wear resistant base stock with silver and barium fluoride/calcium fluoride eutectic added as low and high temperature lubricants, respectively. Potential applications for the PS200 coating are cylinder wall/piston ring lubrication for Stirling engines and foil bearing journal lubrication. In this preliminary program, the silver film overlay thickness was optimized based on tests using a pin-on-disk tribometer. The friction and wear studies were performed in a helium atmosphere at temperatures from 25 to 760 C with a sliding velocity of 2.7 m/s under a 4.9 N load. Films between 1000 and 1500 A provide the best lubrication of the counterface material. The films enrich the sliding surface with lubricant and reduce the initial abrasiveness of the as ground, plasma-sprayed coating surface, thus reducing wear.

Dellacorte, Christopher; Sliney, Harold E.; Deadmore, Daniel L.

1988-01-01

437

Sputtered silver films to improve chromium carbide based solid lubricant coatings for use to 900 C  

NASA Technical Reports Server (NTRS)

Thin silver films, 250 to 3500 A thick, were sputtered onto PS200, a plasma sprayed, chromium carbide based solid lubricant coating, to reduce run-in wear and improve tribological properties. The coating contains bonded chromium carbide as the wear resistant base stock with silver and barium fluoride/calcium fluoride eutectic added as low and high temperature lubricants respectively. Potential applications for the PS200 coating are cylinder wall/piston ring lubrication for Stirling engines and foil bearing journal lubrication. In this preliminary program, the silver film overlay thickness was optimized based on tests using a pin-on-disk tribometer. The friction and wear studies were performed in a helium atmosphere at temperatures from 25 to 760 C with a sliding velocity of 2.7 m/s under a 4.9 N load. Films between 1000 and 1500 A provide the best lubrication of the counterface material. The films enrich the sliding surface with lubricant and reduce the initial abrasiveness of the as ground, plasma-sprayed coating surface, thus reducing wear.

Dellacorte, Christopher; Sliney, Harold E.; Deadmore, Daniel L.

1988-01-01

438

Effect of growth catalysts on gas sensitivity in carbon nanotube film based chemiresistive sensors  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotube (MWCNT) films have been deposited by using plasma enhanced chemical vapor deposition (PECVD) system onto Cr-Au patterned alumina substrates for NO2 and NH3 gas sensing applications, at operating temperature of 200°C. Nanoclusters of different MWCNT-growth catalysts (Fe and Co) have been predeposited onto substrates to promote the growth of the carbon nanotube films with different structural properties. It is demonstrated that the gas sensitivity of the MWCNT films depends on catalyst used for their growth with highest gas sensitivity achieved for Co-grown MWCNT films. The chemiresistor gas response is attributed to the p-type conductivity in semiconducting MWCNTs and the electrical charge transfer is found to be the major sensing mechanism. The results obtained demonstrate that the MWCNT-based sensors exhibit high gas sensitivity, fast response and reversibility, good repeatability and reproducibility, and sub-ppm range detection limit with the gas sensing properties of the MWCNT films tailored by catalyst employed in the PECVD growth process.

Penza, M.; Cassano, G.; Rossi, R.; Rizzo, A.; Signore, M. A.; Alvisi, M.; Lisi, N.; Serra, E.; Giorgi, R.

2007-03-01

439

Radiochromic film based dosimetry of image-guidance procedures on different radiotherapy modalities.  

PubMed

In this work we compare doses from imaging procedures performed on today's state-of-the-art integrated imaging systems using a reference radiochromic film dosimetry system. Skin dose and dose profile measurements from different imaging systems were performed using radiochromic films at different anatomical sites on a humanoid RANDO phantom. EBT3 film was used to measure imaging doses from a TomoTherapy MVCT system, while XRQA2 film was used for dose measurements from kilovoltage imaging systems (CBCT on 21eX and TrueBeam Varian linear accelerators and CyberKnife stereoscopic orthogonal imagers). Maximum measured imaging doses in cGy at head, thorax, and pelvis regions were respectively 0.50, 1.01, and 4.91 for CBCT on 21eX, 0.38, 0.84, and 3.15 for CBCT on TrueBeam, 4.33, 3.86, and 6.50 for CyberKnife imagers, and 3.84, 1.90, and 2.09 for TomoTherapy MVCT. In addition, we have shown how an improved calibration system of XRQA2 film can achieve dose uncertainty level of better than 2% for doses above 0.25 cGy. In addition to simulation-based studies in literature, this study provides the radiation oncology team with data necessary to aid in their decision about imaging frequency for image-guided radiation therapy protocols. PMID:25493527

Nobah, Ahmad; Aldelaijan, Saad; Devic, Slobodan; Tomic, Nada; Seuntjens, Jan; Al-Shabanah, Mohammed; Moftah, Belal

2014-01-01

440

Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films.  

PubMed

Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (10(8) cm(-2)), in the case of hydrogen-treated ND seeding particles, to very high values of 10(11) cm(-2) for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young's moduli of more than 1000 GPa. PMID:23220817

Hees, J; Heidrich, N; Pletschen, W; Sah, R E; Wolfer, M; Williams, O A; Lebedev, V; Nebel, C E; Ambacher, O

2013-01-18

441

Piezoelectric actuated micro-resonators based on the growth of diamond on aluminum nitride thin films  

NASA Astrophysics Data System (ADS)

Unimorph heterostructures based on piezoelectric aluminum nitride (AlN) and diamond thin films are highly desirable for applications in micro- and nanoelectromechanical systems. In this paper, we present a new approach to combine thin conductive boron-doped as well as insulating nanocrystalline diamond (NCD) with sputtered AlN films without the need for any buffer layers between AlN and NCD or polishing steps. The zeta potentials of differently treated nanodiamond (ND) particles in aqueous colloids are adjusted to the zeta potential of AlN in water. Thereby, the nucleation density for the initial growth of diamond on AlN can be varied from very low (108 cm-2), in the case of hydrogen-treated ND seeding particles, to very high values of 1011 cm-2 for oxidized ND particles. Our approach yielding high nucleation densities allows the growth of very thin NCD films on AlN with thicknesses as low as 40 nm for applications such as microelectromechanical beam resonators. Fabricated piezo-actuated micro-resonators exhibit enhanced mechanical properties due to the incorporation of boron-doped NCD films. Highly boron-doped NCD thin films which replace the metal top electrode offer Young’s moduli of more than 1000 GPa.

Hees, J.; Heidrich, N.; Pletschen, W.; Sah, R. E.; Wolfer, M.; Williams, O. A.; Lebedev, V.; Nebel, C. E.; Ambacher, O.

2013-01-01

442

Preparation and characterization agar-based nanocomposite film reinforced by nanocrystalline cellulose.  

PubMed

Nanocrystalline cellulose (NCC) was prepared from microcrystalline cellulose (MCC) with particle size of 24.7 ?m using sulfuric acid hydrolysis technique. The obtained NCC revealed size of 0-100 nm, which the major part of them was about 30 nm. Then different contents (2.5, 5 and 10 wt%) of these NCC incorporated in agar film solution and the morphology, structure, and properties of the nanocomposite films were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transforms infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), mechanical, physical and optical testing. Results showed that the water vapor permeability (WVP) and water solubility (WS) of the agar-based nanocomposite films significantly (P<0.05) decreased about 13% and 21%, respectively, upon increasing the NCC content to 10%. Tensile strength (TS) and Young's modulus (YM) values of nanocomposite films significantly increased (P?0.05) with addition of NCC, whereas the elongation percent (E%) decreased not significantly (P>0.05). In addition, swelling percentage, transparency and light transmission of the films were decreased by incorporating NCC into polymer matrix. PMID:25036597

Atef, Maryam; Rezaei, Masoud; Behrooz, Rabi

2014-09-01

443

In-plane magnetized YIG substrates self-biased by SmCo based sputtered film coatings  

NASA Astrophysics Data System (ADS)

Highly anisotropic SmCo based films with the TbCu7-type structure have been sputter deposited directly onto YIG substrates. The SmCo crystallites have the c axes approximately randomly splayed about the substrate plane such that the easy direction of magnetization of the SmCo film is in the film plane. The in-plane static energy product of the SmCo film layers was about 16 MG Oe. In-plane vibrating sample magnetometer hysteresis loops of the SmCo film and YIG substrate exhibit a composite form with the YIG field reversal shifted into the first quadrant by the looping field from the SmCo film layer. Approximately 4x4 sq mm pieces of YIG substrate have been measured to determine the YIG bias field and field required for reverse saturation of the YIG as a function of the SmCo based film layer thickness to YIG substrate thickness. It is observed that for SmCo to YIG thickness ratios greater than 0.22, the looping field from the SmCo film layer is sufficient to saturate the YIG magnetization in the reverse direction. SmCo film thicknesses in the range from 80 to 120 microns have been used in these studies. Special boundary layers have been used to promote thick film adhesion to the YIG substrates.

Cadieu, F. J.; Hegde, H.; Schloemann, E.; van Hook, H. J.

1994-11-01

444