Anion exchange membranes composed of a poly(2,6-dimethyl-1,4-phenylene oxide) random copolymer functionalized with a bulky phosphonium cation

DOE PAGES

Liu, Ye; Zhang, Bingzi; Kinsinger, Corey L.; ...

2016-01-22

A random copolymer, tris(2,4,6-trimethoxyphenyl) phosphonium functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-TPQP) was cast from three different solvents: dimethyl sulfoxide (DMSO), ethyl lactate, or a 41:59 vol% mixture of DMSO and ethyl lactate. Solvents were selected via analysis of the Hansen solubility parameters to vary the phase separation of the polymer in the films. An optimized mixture of DMSO and ethyl lactate chosen for film fabrication and this film was contrasted with films cast from the neat constituent solvents. Atomic force microscopy identified domains from nanometer to tens of nanometer sizes, while the light microscopy showed features on the order of micron. SAXSmore » revealed a cation scattering peak with a d-spacing from 7 to 15 Å. Trends in conductivity and water diffusion for the membranes vary depending on the solvent from which they are cast. The mixed solvent cast membrane shows a linear Arrhenius behavior indicating fully dissociated cationic/anionic groups, and has the highest bromide conductivity of 3 mS/cm at 95% RH, 90 °C. The ethyl lactate cast membrane shows a linear Arrhenius relation in conductivity, but a Vogel-Tamman-Fulcher behavior in its water self-diffusion. While water increases bromide dissociation, water and bromide transport in these films seems to be decoupled. Lastly, this is particularly true for the film cast from ethyl lactate.« less

Anion exchange membranes composed of a poly(2,6-dimethyl-1,4-phenylene oxide) random copolymer functionalized with a bulky phosphonium cation

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

Liu, Ye; Zhang, Bingzi; Kinsinger, Corey L.

A random copolymer, tris(2,4,6-trimethoxyphenyl) phosphonium functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-TPQP) was cast from three different solvents: dimethyl sulfoxide (DMSO), ethyl lactate, or a 41:59 vol% mixture of DMSO and ethyl lactate. Solvents were selected via analysis of the Hansen solubility parameters to vary the phase separation of the polymer in the films. An optimized mixture of DMSO and ethyl lactate chosen for film fabrication and this film was contrasted with films cast from the neat constituent solvents. Atomic force microscopy identified domains from nanometer to tens of nanometer sizes, while the light microscopy showed features on the order of micron. SAXSmore » revealed a cation scattering peak with a d-spacing from 7 to 15 A. Trends in conductivity and water diffusion for the membranes vary depending on the solvent from which they are cast. The mixed solvent cast membrane shows a linear Arrhenius behavior indicating fully dissociated cationic/anionic groups, and has the highest bromide conductivity of 3 mS/cm at 95% RH, 90 degrees C. The ethyl lactate cast membrane shows a linear Arrhenius relation in conductivity, but a Vogel-Tamman-Fulcher behavior in its water self-diffusion. While water increases bromide dissociation, water and bromide transport in these films seems to be decoupled. This is particularly true for the film cast from ethyl lactate.« less

Anion exchange membranes composed of a poly(2,6-dimethyl-1,4-phenylene oxide) random copolymer functionalized with a bulky phosphonium cation

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

Liu, Ye; Zhang, Bingzi; Kinsinger, Corey L.

A random copolymer, tris(2,4,6-trimethoxyphenyl) phosphonium functionalized poly(2,6-dimethyl-1,4-phenylene oxide) (PPO-TPQP) was cast from three different solvents: dimethyl sulfoxide (DMSO), ethyl lactate, or a 41:59 vol% mixture of DMSO and ethyl lactate. Solvents were selected via analysis of the Hansen solubility parameters to vary the phase separation of the polymer in the films. An optimized mixture of DMSO and ethyl lactate chosen for film fabrication and this film was contrasted with films cast from the neat constituent solvents. Atomic force microscopy identified domains from nanometer to tens of nanometer sizes, while the light microscopy showed features on the order of micron. SAXSmore » revealed a cation scattering peak with a d-spacing from 7 to 15 Å. Trends in conductivity and water diffusion for the membranes vary depending on the solvent from which they are cast. The mixed solvent cast membrane shows a linear Arrhenius behavior indicating fully dissociated cationic/anionic groups, and has the highest bromide conductivity of 3 mS/cm at 95% RH, 90 °C. The ethyl lactate cast membrane shows a linear Arrhenius relation in conductivity, but a Vogel-Tamman-Fulcher behavior in its water self-diffusion. While water increases bromide dissociation, water and bromide transport in these films seems to be decoupled. Lastly, this is particularly true for the film cast from ethyl lactate.« less

Comparison of dielectric properties of additively manufactured vs. solvent cast polyimide dielectrics

DOE PAGES

Appelhans, Leah N.; Keicher, David M.; Lavin, Judith Maria

2016-10-01

The permittivity, dielectric loss, and DC dielectric breakdown strength of additively manufactured, solvent-cast, and commercial polyimide films are reported As expected, commercial films performed better than both AM and solvent-cast lab-made films. Solvent-cast films generally performed better than AM films, although performance depended on the optimization of the material for the specific deposition technique. The most significant degradation of performance in all the lab-made films was in the dispersion of both the x/Df measurements and the dielectric breakdown strength (Weibull β). Commercial films had a breakdown strength of 4891 kV/cm and β = 13.0 whereas the highest performing lab-made filmsmore » had a breakdown strength of 4072 kV/cm and β = 3.8. Furthermore, this increase in dispersion in all the lab-made samples is attributed to higher variability in the preparation, a higher defect level related to fabrication in the lab environment and, for some AM samples, to morphology/topology features resulting from the deposition technique.« less

Comparison of dielectric properties of additively manufactured vs. solvent cast polyimide dielectrics

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

Appelhans, Leah N.; Keicher, David M.; Lavin, Judith Maria

The permittivity, dielectric loss, and DC dielectric breakdown strength of additively manufactured, solvent-cast, and commercial polyimide films are reported As expected, commercial films performed better than both AM and solvent-cast lab-made films. Solvent-cast films generally performed better than AM films, although performance depended on the optimization of the material for the specific deposition technique. The most significant degradation of performance in all the lab-made films was in the dispersion of both the x/Df measurements and the dielectric breakdown strength (Weibull β). Commercial films had a breakdown strength of 4891 kV/cm and β = 13.0 whereas the highest performing lab-made filmsmore » had a breakdown strength of 4072 kV/cm and β = 3.8. Furthermore, this increase in dispersion in all the lab-made samples is attributed to higher variability in the preparation, a higher defect level related to fabrication in the lab environment and, for some AM samples, to morphology/topology features resulting from the deposition technique.« less

Method for forming thin composite solid electrolyte film for lithium batteries

NASA Technical Reports Server (NTRS)

Nagasubramanian, Ganesan (Inventor); Attia, Alan I. (Inventor)

1994-01-01

A composite solid electrolyte film is formed by dissolving a lithium salt such as lithium iodide in a mixture of a first solvent which is a co-solvent for the lithium salt and a binder polymer such as polyethylene oxide and a second solvent which is a solvent for the binder polymer and has poor solubility for the lithium salt. Reinforcing filler such as alumina particles are then added to form a suspension followed by the slow addition of binder polymer. The binder polymer does not agglomerate the alumina particles. The suspension is cast into a uniform film.

Sequential Processing for Organic Photovoltaics: Design Rules for Morphology Control by Tailored Semi-Orthogonal Solvent Blends

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

Aguirre, Jordan C.; Hawks, Steven A.; Ferreira, Amy S.

2015-03-18

Design rules are presented for significantly expanding sequential processing (SqP) into previously inaccessible polymer:fullerene systems by tailoring binary solvent blends for fullerene deposition. Starting with a base solvent that has high fullerene solubility, 2-chlorophenol (2-CP), ellipsometry-based swelling experiments are used to investigate different co-solvents for the fullerene-casting solution. By tuning the Flory-Huggins χ parameter of the 2-CP/co-solvent blend, it is possible to optimally swell the polymer of interest for fullerene interdiffusion without dissolution of the polymer underlayer. In this way solar cell power conversion efficiencies are obtained for the PTB7 (poly[(4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)(3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl)]) and PC61BM (phenyl-C61-butyric acid methyl ester) materials combination thatmore » match those of blend-cast films. Both semicrystalline (e.g., P3HT (poly(3-hexylthiophene-2,5-diyl)) and entirely amorphous (e.g., PSDTTT (poly[(4,8-di(2-butyloxy)benzo[1,2-b:4,5-b']dithiophene-2,6-diyl)-alt-(2,5-bis(4,4'-bis(2-octyl)dithieno[3,2-b:2'3'-d]silole-2,6-diyl)thiazolo[5,4-d]thiazole)]) conjugated polymers can be processed into highly efficient photovoltaic devices using the solvent-blend SqP design rules. Grazing-incidence wide-angle x-ray diffraction experiments confirm that proper choice of the fullerene casting co-solvent yields well-ordered interdispersed bulk heterojunction (BHJ) morphologies without the need for subsequent thermal annealing or the use of trace solvent additives (e.g., diiodooctane). The results open SqP to polymer/fullerene systems that are currently incompatible with traditional methods of device fabrication, and make BHJ morphology control a more tractable problem.« less

Method for molding ceramic powders using a water-based gel casting

DOEpatents

Janney, Mark A.; Omatete, Ogbemi O.

1991-07-02

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product any be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

Method for molding ceramic powders using a water-based gel casting process

DOEpatents

Jenny, Mark A.; Omalete, Ogbemi O.

1992-09-08

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

21 CFR 178.3950 - Tetrahydrofuran.

Code of Federal Regulations, 2010 CFR

2010-04-01

... section. (a) It is used as a solvent in the casting of film from a solution of polymeric resins of vinyl... another in any combination, or it may be used as a solvent in the casting of film prepared from vinyl... in the film does not exceed 1.5 percent by weight of film. ...

Precursor-route ZnO films from a mixed casting solvent for high performance aqueous electrolyte-gated transistors.

PubMed

Althagafi, Talal M; Algarni, Saud A; Al Naim, Abdullah; Mazher, Javed; Grell, Martin

2015-12-14

We significantly improved the performance of precursor-route semiconducting zinc oxide (ZnO) films in electrolyte-gated thin film transistors (TFTs). We find that the organic precursor to ZnO, zinc acetate (ZnAc), dissolves more readily in a 1 : 1 mixture of ethanol (EtOH) and acetone than in pure EtOH, pure acetone, or pure isopropanol. XPS and SEM characterisation show improved morphology of ZnO films converted from a mixed solvent cast ZnAc precursor compared to the EtOH cast precursor. When gated with a biocompatible electrolyte, phosphate buffered saline (PBS), ZnO thin film transistors (TFTs) derived from mixed solvent cast ZnAc give 4 times larger field effect current than similar films derived from ZnAc cast from pure EtOH. The sheet resistance at VG = VD = 1 V is 30 kΩ □(-1), lower than for any organic TFT, and lower than for any electrolyte-gated ZnO TFT reported to date.

Process for manufacturing a lithium alloy electrochemical cell

DOEpatents

Bennett, William R.

1992-10-13

A process for manufacturing a lithium alloy, metal sulfide cell tape casts slurried alloy powders in an organic solvent containing a dissolved thermoplastic organic binder onto casting surfaces. The organic solvent is then evaporated to produce a flexible tape removable adhering to the casting surface. The tape is densified to increase its green strength and then peeled from the casting surface. The tape is laminated with a separator containing a lithium salt electrolyte and a metal sulfide electrode to form a green cell. The binder is evaporated from the green cell at a temperature lower than the melting temperature of the lithium salt electrolyte. Lithium alloy, metal sulfide and separator powders may be tape cast.

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

Ghadkolai, Milad Azami; Creager, Stephen; Nanda, Jagjit

Lithium titanate (Li 4Ti 5O 12) powders with and without molybdenum doping (LTO and MoLTO respectively) were synthesized by a solid-state method and used to fabricate electrodes on Cu foil using a normal tape-cast method and a novel freeze-tape-cast method. Modest molybdenum doping produces a significant electronic conductivity increase (e.g. 1 mS cm -1 for MoLTO vs 10 -7 mS cm -1 for LTO) that is thought to reflect a partial Ti 4+ reduction to Ti 3+ with charge compensation by the Mo 6+ dopant, producing a stable mixed-valent Ti 4+/3+ state. Freeze-tape-cast electrodes were fabricated by a variant ofmore » the normal tape-cast method that includes a rapid freezing step in which the solvent in the Cu-foil-supported slurry is rapidly frozen on a cold finger then subsequently sublimed to create unidirectional columnar macropores in the electrode. The resulting electrodes exhibit high porosity and low tortuosity which enhances electrolyte accessibility throughout the full electrode thickness. Freeze-tape-cast electrodes subjected to galvanostatic charge-discharge testing as cathodes in cells vs. a lithium metal anode exhibit higher specific capacity and lower capacity loss at high discharge rates compared with normal-tape-cast electrodes of the same mass loading, despite the fact that the freeze-tape-cast electrodes are nearly twice as thick as the normal tape cast electrodes.« less

Sophorolipid-induced dimpling and increased porosity in solvent-cast short-chain polyhydroxyalkanoate films: impact on thermo-mechanical properties

USDA-ARS?s Scientific Manuscript database

Sophorolipids (SL; microbial glycolipids) were used as additives in solvent-cast short-chain polyhydroxyalkanoate (sc-PHA) films to enhance surface roughness and porosity. Poly-3-hydroxybutyrate (PHB), poly-(6%)-3-hydroxybutyrate-co-(94%)-3-hydroxyvalerate (PHB/V), and poly-(90%)-3-hydroxybutyrate-c...

21 CFR 178.3950 - Tetrahydrofuran.

Code of Federal Regulations, 2011 CFR

2011-04-01

... provisions of this section. (a) It is used as a solvent in the casting of film from a solution of polymeric... copolymerized with one another in any combination, or it may be used as a solvent in the casting of film... of tetrahydrofuran in the film does not exceed 1.5 percent by weight of film. ...

21 CFR 178.3950 - Tetrahydrofuran.

Code of Federal Regulations, 2013 CFR

2013-04-01

... provisions of this section. (a) It is used as a solvent in the casting of film from a solution of polymeric... copolymerized with one another in any combination, or it may be used as a solvent in the casting of film... of tetrahydrofuran in the film does not exceed 1.5 percent by weight of film. ...

21 CFR 178.3950 - Tetrahydrofuran.

Code of Federal Regulations, 2014 CFR

2014-04-01

... solvent in the casting of film from a solution of polymeric resins of vinyl chloride, vinyl acetate, or..., or it may be used as a solvent in the casting of film prepared from vinyl chloride copolymers complying with § 177.1980 of this chapter. (b) The residual amount of tetrahydrofuran in the film does not...

21 CFR 178.3950 - Tetrahydrofuran.

Code of Federal Regulations, 2012 CFR

2012-04-01

... provisions of this section. (a) It is used as a solvent in the casting of film from a solution of polymeric... copolymerized with one another in any combination, or it may be used as a solvent in the casting of film... of tetrahydrofuran in the film does not exceed 1.5 percent by weight of film. ...

Freeze Tape Cast Thick Mo Doped Li 4Ti 5O 12 Electrodes for Lithium-Ion Batteries

DOE PAGES

Ghadkolai, Milad Azami; Creager, Stephen; Nanda, Jagjit; ...

2017-08-30

Lithium titanate (Li 4Ti 5O 12) powders with and without molybdenum doping (LTO and MoLTO respectively) were synthesized by a solid-state method and used to fabricate electrodes on Cu foil using a normal tape-cast method and a novel freeze-tape-cast method. Modest molybdenum doping produces a significant electronic conductivity increase (e.g. 1 mS cm -1 for MoLTO vs 10 -7 mS cm -1 for LTO) that is thought to reflect a partial Ti 4+ reduction to Ti 3+ with charge compensation by the Mo 6+ dopant, producing a stable mixed-valent Ti 4+/3+ state. Freeze-tape-cast electrodes were fabricated by a variant ofmore » the normal tape-cast method that includes a rapid freezing step in which the solvent in the Cu-foil-supported slurry is rapidly frozen on a cold finger then subsequently sublimed to create unidirectional columnar macropores in the electrode. The resulting electrodes exhibit high porosity and low tortuosity which enhances electrolyte accessibility throughout the full electrode thickness. Freeze-tape-cast electrodes subjected to galvanostatic charge-discharge testing as cathodes in cells vs. a lithium metal anode exhibit higher specific capacity and lower capacity loss at high discharge rates compared with normal-tape-cast electrodes of the same mass loading, despite the fact that the freeze-tape-cast electrodes are nearly twice as thick as the normal tape cast electrodes.« less

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)

Criss, Robert Randolph, Jr.

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.

Drug-printing by flexographic printing technology--a new manufacturing process for orodispersible films.

PubMed

Janssen, Eva Maria; Schliephacke, Ralf; Breitenbach, Armin; Breitkreutz, Jörg

2013-01-30

Orodispersible films (ODFs) are intended to disintegrate within seconds when placed onto the tongue. The common way of manufacturing is the solvent casting method. Flexographic printing on drug-free ODFs is introduced as a highly flexible and cost-effective alternative manufacturing method in this study. Rasagiline mesylate and tadalafil were used as model drugs. Printing of rasagiline solutions and tadalafil suspensions was feasible. Up to four printing cycles were performed. The possibility to employ several printing cycles enables a continuous, highly flexible manufacturing process, for example for individualised medicine. The obtained ODFs were characterised regarding their mechanical properties, their disintegration time, API crystallinity and homogeneity. Rasagiline mesylate did not recrystallise after the printing process. Relevant film properties were not affected by printing. Results were comparable to the results of ODFs manufactured with the common solvent casting technique, but the APIs are less stressed through mixing, solvent evaporation and heat. Further, loss of material due to cutting jumbo and daughter rolls can be reduced. Therefore, a versatile new manufacturing technology particularly for processing high-potent low-dose or heat sensitive drugs is introduced in this study. Copyright © 2012 Elsevier B.V. All rights reserved.

Method for forming thin composite solid electrolyte film for lithium batteries

NASA Technical Reports Server (NTRS)

Attia, Alan I. (Inventor); Nagasubramanian, Ganesan (Inventor)

1997-01-01

A composite solid electrolyte film is formed by dissolving a lithium salt such as lithium iodide in a mixture of a first solvent which is a cosolvent for the lithium salt and a binder polymer such as polyethylene oxide and a second solvent which is a solvent for the binder polymer and has poor solubility for the lithium salt. Reinforcing filler such as alumina particles are then added to form a suspension followed by the slow addition of binder polymer. The binder polymer does not agglomerate the alumina particles. The suspension is cast into a uniform film.

Water-induced nanochannel networks in self-assembled block ionomers

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

Mineart, Kenneth P.; Al-Mohsin, Heba A.; Lee, Byeongdu

2016-03-07

Block ionomers cast from solution exhibit solvent-templated morphologies that can be altered by solvent-vapor annealing. When cast from a mixed solvent, a midblock-sulfonated pentablock ion- omer self-assembles into spherical ionic microdomains that are loosely connected. Upon exposure to liquid water, nanoscale channels irreversibly develop between the microdomains due to swelling and form a continuous mesoscale network. We use electron tomography and real-time X-ray scat- tering to follow this transformation and show that the resultant morphology provides a highly effec- tive diffusive pathway.

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

2008-05-06

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, Paul J.; Baskaran, Suresh; Bontha, Jagannadha R.; Liu, Jun

1999-01-01

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s).

Mesoporous-silica films, fibers, and powders by evaporation

DOEpatents

Bruinsma, P.J.; Baskaran, S.; Bontha, J.R.; Liu, J.

1999-07-13

This invention pertains to surfactant-templated nanometer-scale porosity of a silica precursor solution and forming a mesoporous material by first forming the silica precursor solution into a preform having a high surface area to volume ratio, then rapid drying or evaporating a solvent from the silica precursor solution. The mesoporous material may be in any geometric form, but is preferably in the form of a film, fiber, powder or combinations thereof. The rapid drying or evaporation of solvent from the solution is accomplished by layer thinning, for example spin casting, liquid drawing, and liquid spraying respectively. Production of a film is by layer thinning, wherein a layer of the silica precursor solution is formed on a surface followed by removal of an amount of the silica precursor solution and leaving a geometrically thinner layer of the silica precursor solution from which the solvent quickly escapes via evaporation. Layer thinning may be by any method including but not limited to squeegeeing and/or spin casting. In powder formation by spray drying, the same conditions of fast drying exists as in spin-casting (as well as in fiber spinning) because of the high surface-area to volume ratio of the product. When a powder is produced by liquid spraying, the particles or micro-bubbles within the powder are hollow spheres with walls composed of mesoporous silica. Mesoporous fiber formation starts with a similar silica precursor solution but with an added pre-polymer making a pituitous mixture that is drawn into a thin strand from which solvent is evaporated leaving the mesoporous fiber(s). 24 figs.

Casting Of Multilayer Ceramic Tapes

NASA Technical Reports Server (NTRS)

Collins, Earl R., Jr.

1991-01-01

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

Design and evaluation of bilayered buccal film preparations for local administration of lidocaine hydrochloride.

PubMed

Preis, Maren; Woertz, Christina; Schneider, Katharina; Kukawka, Jennifer; Broscheit, Jens; Roewer, Norbert; Breitkreutz, Jörg

2014-04-01

Bilayered oromucosal film preparations (buccal films) offer a promising way to enable drug administration via the oral cavity. Adding a non-soluble or slowly eroding/dissolving backing layer to a mucoadhesive drug-loaded layer enables unidirectional drug delivery. The aim of this study was to investigate different approaches to the manufacture of bilayered films and to examine their properties by applying different characterization methods including an optimized experimental setup for the study of drug release from bilayered films. A solvent suitability study was performed screening over 15 polymers with respect to their feasibility for viscous film formation for film preparation by solvent casting method. Two methods (double-casting and pasting) were found as suitable methods for bilayered film manufacturing. Results from drug release experiments indicated that slowly eroding hypromellose backing layer films revealed the best shielding of the drug-loaded layer to enable unidirectional drug release. In summary, manufacturing of bilayered films using the described methods was feasible. Furthermore, the use of an optimized experimental setup for drug dissolution studies enabled monitoring of drug release without delays in sampling. Copyright © 2014 Elsevier B.V. All rights reserved.

Simultaneous tuning of chemical composition and topography of copolymer surfaces: micelles as building blocks.

PubMed

Zhao, Ning; Zhang, Xiaoyan; Zhang, Xiaoli; Xu, Jian

2007-05-14

A simple method is described for controlling the surface chemical composition and topography of the diblock copolymer poly(styrene)-b-poly(dimethylsiloxane)(PS-b-PDMS) by casting the copolymer solutions from solvents with different selectivities. The surface morphology and chemical composition were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS), respectively, and the wetting behavior was studied by water contact angle (CA) and sliding angle (SA) and by CA hysteresis. Chemical composition and morphology of the surface depend on solvent properties, humidity of the air, solution concentration, and block lengths. If the copolymer is cast from a common solvent, the resultant surface is hydrophobic, with a flat morphology, and dominated by PDMS on the air side. From a PDMS-selective solvent, the surface topography depends on the morphology of the micelles. Starlike micelles give rise to a featureless surface nearly completely covered by PDMS, while crew-cut-like micelles lead to a rough surface with a hierarchical structure that consists partly of PDMS. From a PS-selective solvent, however, surface segregation of PDMS was restricted, and the surface morphology can be controlled by vapor-induced phase separation. On the basis of the tunable surface roughness and PDMS concentration on the air side, water repellency of the copolymer surface could be tailored from hydrophobic to superhydrophobic. In addition, reversible switching behavior between hydrophobic and superhydrophobic can be achieved by exposing the surface to solvents with different selectivities.

Effects of Block Length and Membrane Processing Conditions on the Morphology and Properties of Perfluorosulfonated Poly(arylene ether sulfone) Multiblock Copolymer Membranes for PEMFC.

PubMed

Assumma, Luca; Nguyen, Huu-Dat; Iojoiu, Cristina; Lyonnard, Sandrine; Mercier, Régis; Espuche, Eliane

2015-07-01

Perfluorosulfonated poly(arylene ether sulfone) multiblock copolymers have been shown to be promising as proton exchange membranes. The commonly used approach for preparation of the membrane is solvent casting; the properties of the resulting membranes are very dependent on the membrane processing conditions. In this paper, we study the effects of block length, selectivity of the solvent, and thermal treatment on the membrane properties such as morphology, water uptake, and ionic conductivity. DiMethylSulfOxide (DMSO), and DiMethylAcetamide (DMAc) were selected as casting solvents based on the Flory-Huggins parameter calculated by inversion gas chromatography (IGC). It was found that the solvent selectivity has a mild impact on the mean size of the ionic domains and the expansion upon swelling, while it dramatically affects the supramolecular ordering of the blocks. The membranes cast from DMSO exhibit more interconnected ionic clusters yielding higher conductivities and water uptake as compared to membranes cast from DMAc. A 10-fold increase in proton conductivity was achieved after thermal annealing of membranes at 150 °C, and the ionomers with longer block lengths show conductivities similar to Nafion at 80 °C and low relative humidity (30%).

Method Of Making An Ultracapacitor Electrode

DOEpatents

Wei, Chang; Jerabek, Elihu Calvin; DeJager, Katherine Dana; LeBlanc, Jr., Oliver Harris

2003-05-06

A paste of organic solvent with dissolved organic salt and active carbon is formed and a uniform film of the paste is applied onto a substrate by casting the paste into a clearance between a knife blade and the substrate. The paste is evaporated to form a paste electrode for an ultracapacitor.

Method of making an ultracapacitor electrode

DOEpatents

Wei, Chang; Jerabek, Elihu Calvin; DeJager, Katherine Dana; LeBlanc, Jr., Oliver Harris

2001-10-16

A paste of organic solvent with dissolved organic salt and active carbon is formed and a uniform film of the paste is applied onto a substrate by casting the paste into a clearance between a knife blade and the substrate. The paste is evaporated to form a paste electrode for an ultracapacitor.

A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process.

PubMed

Deng, Yao; Zhang, Mengjiao; Chen, Xianchun; Pu, Ximing; Liao, Xiaoming; Huang, Zhongbing; Yin, Guangfu

2017-08-01

Desirable scaffolds for tissue engineering should be biodegradable carriers to supply suitable microenvironments mimicked the extracellular matrices for desired cellular interactions and to provide supports for the formation of new tissues. In this work, a kind of slightly soluble bioactive ceramic akermanite (AKT) powders were aboratively selected and introduced in the PLGA matrix, a novel l-lactide modified AKT/poly (lactic- co -glycolic acid) (m-AKT/PLGA) composite scaffold was fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process. The effects of m-AKT contents on properties of composite scaffolds and on MC3T3-E1 cellular behaviors in vitro have been primarily investigated. The fabricated scaffolds exhibited three-dimensional porous networks, in which homogenously distributed cavities in size of 300-400 μm were interconnected by some smaller holes in a size of 100-200 μm. Meanwhile, the mechanical structure of scaffolds was reinforced by the introduction of m-AKT. Moreover, alkaline ionic products released by m-AKT could neutralize the acidic degradation products of PLGA, and the apatite-mineralization ability of scaffolds could be largely improved. More valuably, significant promotions on adhesion, proliferation, and differentiation of MC3T3-E1 have been observed, which implied the calcium, magnesium and especially silidous ions released sustainably from composite scaffolds could regulate the behaviors of osteogenesis-related cells.

A novel akermanite/poly (lactic-co-glycolic acid) porous composite scaffold fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process

PubMed Central

Deng, Yao; Zhang, Mengjiao; Chen, Xianchun; Pu, Ximing; Liao, Xiaoming; Huang, Zhongbing

2017-01-01

Abstract Desirable scaffolds for tissue engineering should be biodegradable carriers to supply suitable microenvironments mimicked the extracellular matrices for desired cellular interactions and to provide supports for the formation of new tissues. In this work, a kind of slightly soluble bioactive ceramic akermanite (AKT) powders were aboratively selected and introduced in the PLGA matrix, a novel l-lactide modified AKT/poly (lactic-co-glycolic acid) (m-AKT/PLGA) composite scaffold was fabricated via a solvent casting-particulate leaching method improved by solvent self-proliferating process. The effects of m-AKT contents on properties of composite scaffolds and on MC3T3-E1 cellular behaviors in vitro have been primarily investigated. The fabricated scaffolds exhibited three-dimensional porous networks, in which homogenously distributed cavities in size of 300–400 μm were interconnected by some smaller holes in a size of 100–200 μm. Meanwhile, the mechanical structure of scaffolds was reinforced by the introduction of m-AKT. Moreover, alkaline ionic products released by m-AKT could neutralize the acidic degradation products of PLGA, and the apatite-mineralization ability of scaffolds could be largely improved. More valuably, significant promotions on adhesion, proliferation, and differentiation of MC3T3-E1 have been observed, which implied the calcium, magnesium and especially silidous ions released sustainably from composite scaffolds could regulate the behaviors of osteogenesis-related cells. PMID:28798869

Vacuum casting of thick polymeric films

NASA Technical Reports Server (NTRS)

Cuddihy, E. F.; Moacanin, J.

1979-01-01

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.

Method for making thick and/or thin film

DOEpatents

Pham, Ai Quoc; Glass, Robert S.

2004-11-02

A method to make thick or thin films a very low cost. The method is generally similar to the conventional tape casting techniques while being more flexible and versatile. The invention involves preparing a slip (solution) of desired material and including solvents such as ethanol and an appropriate dispersant to prevent agglomeration. The slip is then sprayed on a substrate to be coated using an atomizer which spreads the slip in a fine mist. Upon hitting the substrate, the solvent evaporates, leaving a green tape containing the powder and other additives, whereafter the tape may be punctured, cut, and heated for the desired application. The tape thickness can vary from about 1 .mu.m upward.

Understanding Solvent Manipulation of Morphology in Bulk-Heterojunction Organic Solar Cells.

PubMed

Chen, Yuxia; Zhan, Chuanlang; Yao, Jiannian

2016-10-06

Film morphology greatly influences the performance of bulk-heterojunction (BHJ)-structure-based solar cells. It is known that an interpenetrating bicontinuous network with nanoscale-separated donor and acceptor phases for charge transfer, an ordered molecular packing for exciton diffusion and charge transport, and a vertical compositionally graded structure for charge collection are prerequisites for achieving highly efficient BHJ organic solar cells (OSCs). Therefore, control of the morphology to obtain an ideal structure is a key problem. For this solution-processing BHJ system, the solvent participates fully in film processing. Its involvement is critical in modifying the nanostructure of BHJ films. In this review, we discuss the effects of solvent-related methods on the morphology of BHJ films, including selection of the casting solvent, solvent mixture, solvent vapor annealing, and solvent soaking. On the basis of a discussion on interaction strength and time between solvent and active materials, we believe that the solvent-morphology-performance relationship will be clearer and that solvent selection as a means to manipulate the morphology of BHJ films will be more rational. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solvent-Free Manufacturing of Electrodes for Lithium-ion Batteries

NASA Astrophysics Data System (ADS)

Ludwig, Brandon; Zheng, Zhangfeng; Shou, Wan; Wang, Yan; Pan, Heng

2016-03-01

Lithium ion battery electrodes were manufactured using a new, completely dry powder painting process. The solvents used for conventional slurry-cast electrodes have been completely removed. Thermal activation time has been greatly reduced due to the time and resource demanding solvent evaporation process needed with slurry-cast electrode manufacturing being replaced by a hot rolling process. It has been found that thermal activation time to induce mechanical bonding of the thermoplastic polymer to the remaining active electrode particles is only a few seconds. Removing the solvent and drying process allows large-scale Li-ion battery production to be more economically viable in markets such as automotive energy storage systems. By understanding the surface energies of various powders which govern the powder mixing and binder distribution, bonding tests of the dry-deposited particles onto the current collector show that the bonding strength is greater than slurry-cast electrodes, 148.8 kPa as compared to 84.3 kPa. Electrochemical tests show that the new electrodes outperform conventional slurry processed electrodes, which is due to different binder distribution.

Carbon nanotube embedded PVDF membranes: Effect of solvent composition on the structural morphology for membrane distillation

NASA Astrophysics Data System (ADS)

Mapunda, Edgar C.; Mamba, Bhekie B.; Msagati, Titus A. M.

2017-08-01

Rapid population increase, growth in industrial and agricultural sectors and global climate change have added significant pressure on conventional freshwater resources. Tapping freshwater from non-conventional water sources such as desalination and wastewater recycling is considered as sustainable alternative to the fundamental challenges of water scarcity. However, affordable and sustainable technologies need to be applied for the communities to benefit from the treatment of non-conventional water source. Membrane distillation is a potential desalination technology which can be used sustainably for this purpose. In this work multi-walled carbon nanotube embedded polyvinylidene fluoride membranes for application in membrane distillation desalination were prepared via non-solvent induced phase separation method. The casting solution was prepared using mixed solvents (N, N-dimethylacetamide and triethyl phosphate) at varying ratios to study the effect of solvent composition on membrane morphological structures. Membrane morphological features were studied using a number of techniques including scanning electron microscope, atomic force microscope, SAXSpace tensile strength analysis, membrane thickness, porosity and contact angle measurements. It was revealed that membrane hydrophobicity, thickness, tensile strength and surface roughness were increasing as the composition of N, N-dimethylacetamide in the solvent was increasing with maximum values obtained between 40 and 60% N, N-dimethylacetamide. Internal morphological structures were changing from cellular structures to short finger-like and sponge-like pores and finally to large macro void type of pores when the amount of N, N-dimethylacetamide in the solvent was changed from low to high respectively. Multi-walled carbon nanotube embedded polyvinylidene fluoride membranes of desired morphological structures and physical properties can be synthesized by regulating the composition of solvents used to prepare the casting solution.

Ultrasonic Substrate Vibration-Assisted Drop Casting (SVADC) for the Fabrication of Photovoltaic Solar Cell Arrays and Thin-Film Devices.

PubMed

Eslamian, Morteza; Zabihi, Fatemeh

2015-12-01

A simple, low-cost, versatile, and potentially scalable casting method is proposed for the fabrication of micro- and nano-thin films, herein termed as ultrasonic "substrate vibration-assisted drop casting" (SVADC). The impingement of a solution drop onto a substrate in a simple process called drop casting, usually results in spreading of the liquid solution and the formation of a non-uniform thin solid film after solvent evaporation. Our previous and current supporting results, as well as few similar reports by others, confirm that imposing ultrasonic vibration on the substrate can simply convert the uncontrollable drop casting method into a controllable coating technique. Therefore, the SVADC may be used to fabricate an array of emerging thin-film solar cells, such as polymer, perovskite, and quantum-dot solar cells, as well as other small thin-film devices, in a roll-to-roll and automated fabrication process. The preliminary results demonstrate a ten-fold increase in electrical conductivity of PSS made by SVADC compared with the film made by conventional drop casting. Also, simple planar perovskite solar cells made here using SVADC show promising performance with an efficiency of over 3 % for a simple structure without performing process optimization or using expensive materials and treatments.

Electroactive poly(vinylidene fluoride)-based structures for advanced applications.

PubMed

Ribeiro, Clarisse; Costa, Carlos M; Correia, Daniela M; Nunes-Pereira, João; Oliveira, Juliana; Martins, Pedro; Gonçalves, Renato; Cardoso, Vanessa F; Lanceros-Méndez, Senentxu

2018-04-01

Poly(vinylidene fluoride) (PVDF) and its copolymers are the polymers with the highest dielectric constants and electroactive responses, including piezoelectric, pyroelectric and ferroelectric effects. This semicrystalline polymer can crystallize in five different forms, each related to a different chain conformation. Of these different phases, the β phase is the one with the highest dipolar moment and the highest piezoelectric response; therefore, it is the most interesting for a diverse range of applications. Thus, a variety of processing methods have been developed to induce the formation of the polymer β phase. In addition, PVDF has the advantage of being easily processable, flexible and low-cost. In this protocol, we present a number of reproducible and effective methods to produce β-PVDF-based morphologies/structures in the form of dense films, porous films, 3D scaffolds, patterned structures, fibers and spheres. These structures can be fabricated by different processing techniques, including doctor blade, spin coating, printing technologies, non-solvent-induced phase separation (NIPS), temperature-induced phase separation (TIPS), solvent-casting particulate leaching, solvent-casting using a 3D nylon template, freeze extraction with a 3D poly(vinyl alcohol) (PVA) template, replica molding, and electrospinning or electrospray, with the fabrication method depending on the desired characteristics of the structure. The developed electroactive structures have shown potential to be used in a wide range of applications, including the formation of sensors and actuators, in biomedicine, for energy generation and storage, and as filtration membranes.

Advanced separators based on aromatic polymer for high energy density lithium batteries

DOEpatents

Zhang, Zhengcheng; Woo, Jung-Je; Amine, Khalil

2017-03-21

A process includes casting a solution including poly(phenylene oxide), inorganic nanoparticles, a solvent, and a non-solvent on a substrate; and removing the solvent to form a porous film; wherein: the porous film is configured for use as a porous separator for a lithium ion battery.

From micelle supramolecular assemblies in selective solvents to isoporous membranes.

PubMed

Nunes, Suzana P; Karunakaran, Madhavan; Pradeep, Neelakanda; Behzad, Ali Reza; Hooghan, Bobby; Sougrat, Rachid; He, Haoze; Peinemann, Klaus-Viktor

2011-08-16

The supramolecular assembly of PS-b-P4VP copolymer micelles induced by selective solvent mixtures was used to manufacture isoporous membranes. Micelle order in solution was confirmed by cryo-scanning electron microscopy in casting solutions, leading to ordered pore morphology. When dioxane, a solvent that interacts poorly with the micelle corona, was added to the solution, polymer-polymer segment contact was preferential, increasing the intermicelle contact. Immersion in water gave rise to asymmetric porous membranes with exceptional pore uniformity and high porosity. The introduction of a small number of carbon nanotubes to the casting solution improved the membrane stability and the reversibility of the gate response in the presence of different pH values.

Functionalizing CNTs for Making Epoxy/CNT Composites

NASA Technical Reports Server (NTRS)

Chen, Jian; Rajagopal, Ramasubramaniam

2009-01-01

Functionalization of carbon nanotubes (CNTs) with linear molecular side chains of polyphenylene ether (PPE) has been shown to be effective in solubilizing the CNTs in the solvent components of solutions that are cast to make epoxy/CNT composite films. (In the absence of solubilization, the CNTs tend to clump together instead of becoming dispersed in solution as needed to impart, to the films, the desired CNT properties of electrical conductivity and mechanical strength.) Because the PPE functionalizes the CNTs in a noncovalent manner, the functionalization does not damage the CNTs. The functionalization can also be exploited to improve the interactions between CNTs and epoxy matrices to enhance the properties of the resulting composite films. In addition to the CNTs, solvent, epoxy resin, epoxy hardener, and PPE, a properly formulated solution also includes a small amount of polycarbonate, which serves to fill voids that, if allowed to remain, would degrade the performance of the film. To form the film, the solution is drop-cast or spin-cast, then the solvent is allowed to evaporate.

Drug Delivery for Peripheral Nerve Regeneration

DTIC Science & Technology

2015-11-01

components are shown in Figure 2. The solvent casting method was used for manufacturing devices, with the 75/25 PLGA pellets dissolved in acetone at a...bottom-up process that minimizes wrinkling of the sheet as it expands and contracts. Following 4 hours on a hot plate, the sheet was submerged into...glass transition temperature (40-60°C), eliminating many traditional sterilization methods like autoclaving. We evaluated deformation of the device

Semiconductor surface protection material

NASA Technical Reports Server (NTRS)

Packard, R. D. (Inventor)

1973-01-01

A method and a product for protecting semiconductor surfaces is disclosed. The protective coating material is prepared by heating a suitable protective resin with an organic solvent which is solid at room temperature and converting the resulting solution into sheets by a conventional casting operation. Pieces of such sheets of suitable shape and thickness are placed on the semiconductor areas to be coated and heat and vacuum are then applied to melt the sheet and to drive off the solvent and cure the resin. A uniform adherent coating, free of bubbles and other defects, is thus obtained exactly where it is desired.

Solvent additive effects on small molecule crystallization in bulk heterojunction solar cells probed during spin casting.

PubMed

Perez, Louis A; Chou, Kang Wei; Love, John A; van der Poll, Thomas S; Smilgies, Detlef-M; Nguyen, Thuc-Quyen; Kramer, Edward J; Amassian, Aram; Bazan, Guillermo C

2013-11-26

Solvent additive processing can lead to drastic improvements in the power conversion efficiency (PCE) in solution processable small molecule (SPSM) bulk heterojunction solar cells. In situ grazing incidence wide-angle X-ray scattering is used to investigate the kinetics of crystallite formation during and shortly after spin casting. The additive is shown to have a complex effect on structural evolution invoking polymorphism and enhanced crystalline quality of the donor SPSM. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Extrusion of xylans extracted from corn cobs into biodegradable polymeric materials.

PubMed

Bahcegul, Erinc; Akinalan, Busra; Toraman, Hilal E; Erdemir, Duygu; Ozkan, Necati; Bakir, Ufuk

2013-12-01

Solvent casting technique, which comprises multiple energy demanding steps including the dissolution of a polymer in a solvent followed by the evaporation of the solvent from the polymer solution, is currently the main technique for the production of xylan based polymeric materials. The present study shows that sufficient water content renders arabinoglucuronoxylan (AGX) polymers extrudable, enabling the production of AGX based polymeric materials in a single step via extrusion, which is economically advantageous to solvent casting process for mass production. AGX polymers with water content of 27% were found to yield extrudates at an extrusion temperature of 90°C. The extruded strips showed very good mechanical properties with an ultimate tensile strength of 76 ± 6 MPa and elongation at break value of 35 ± 8%, which were superior to the mechanical properties of the strips obtained from polylactic acid. Copyright © 2013 Elsevier Ltd. All rights reserved.

Regenerated cellulose capsules for controlled drug delivery: Part III. Developing a fabrication method and evaluating extemporaneous utility for controlled-release.

PubMed

Bhatt, Bhavik; Kumar, Vijay

2016-08-25

In this article, we describe a method to utilize cellulose dissolved in dimethyl sulfoxide and paraformaldehyde solvent system to fabricate two-piece regenerated cellulose hard shell capsules for their potential use as an oral controlled drug delivery a priori vehicle. A systematic evaluation of solution rheology as well as resulting capsule mechanical, visual and thermal analysis was performed to develop a suitable method to repeatedly fabricate RC hard shell capsule halves. Because of the viscoelastic nature of the cellulose solution, a combination of dip-coating and casting method, herein referred to as dip-casting method, was developed. The dip-casting method was formalized by utilizing two-stage 2(2) full factorial design approach in order to determine a suitable approach to fabricate capsules with minimal variability. Thermal annealing is responsible for imparting shape rigidity of the capsules. Proof-of-concept analysis for the utility of these capsules in controlled drug delivery was performed by evaluating the release of KCl from them as well as from commercially available USP equivalent formulations. Release of KCl from cellulose capsules was comparable to extended release capsule formulation. Copyright © 2016 Elsevier B.V. All rights reserved.

Anisotropic membranes for gas separation

DOEpatents

Gollan, A.Z.

1987-07-21

A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7--25 C and then air dried at ambient temperature, typically 10--30 C. 2 figs.

Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells and method for fabrication thereof

NASA Technical Reports Server (NTRS)

Schroeder, James E. (Inventor); Anderson, Harlan U. (Inventor)

1990-01-01

An unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

Effect of Tunable Surface Potential on the Structure of Spin-Cast Polymeric Blend Films

NASA Astrophysics Data System (ADS)

Hawker, C.; Huang, E.; Russell, T. P.

1998-03-01

The demixing of binary polymeric mixtures has been studied with various surface potentials. This was performed by spin casting polystyrene/poly(methyl methacrylate) mixtures on to silicon substrates that had been modified with an end-grafted random copolymer brush layer. The composition of the random copolymer brush, containing the same monomeric components as the homopolymers can be varied in a precise manner over the entire concentration range. Atomic force and optical microscopy were used to study the morphology formed during spin casting and after annealing. Further insight into the structure was gained by rinsing these films with preferential solvents to remove one of the constituents and by performing the microscopy measurements. Finally, x-ray photoelectron spectroscopy, XPS, was used to elucidate the composition of the film near the air/polymer interface. Our data show that the resulting thin film structure depends strongly on the composition of the end grafted random copolymer film. Furthermore, the effect of thickness, solvent used in casting, and annealing conditions will be addressed.

Thermoplastic/Nanotube Composite Fibers

NASA Astrophysics Data System (ADS)

Haggenmueller, Reto; Fischer, John; Winey, Karen

2000-03-01

A combination of solvent casting and melt mixing methods are used to compound selected thermoplastics with single-wall carbon nanotubes. Subsequently, melt extrusion is used to form thermoplastic-nanotube composite fibers. The structural characteristics are investigated by electron microscopy and x-ray scattering methods. In addition the electrical, thermal and mechanical properties were measured. Correlations are sought between the viscoelastic properties of the compounded materials, the nanotube loading and elongation ratio after spinning, and the properties of the resultant fibers.

Enhanced thermal stability of biomedical thermoplastic polyurethane with the addition of cellulose nanocrystals

Treesearch

Jen-Chieh Liu; Darren J. Martin; Robert J. Moon; Jeffrey P. Youngblood

2015-01-01

Freeze-dried cellulose nanocrystals (CNCs) were dispersed in the thermoplastic polyurethane [Pellethane 2363-55D (P55D)] by a solvent casting method to fabricate CNC-reinforced nanocomposites. This study demonstrated that the addition of small amounts (1–5 wt %) of CNCs to P55D increased the thermal degradation temperature while maintaining a similar stiffness,...

Anisotropic membranes for gas separation

DOEpatents

Gollan, Arye Z.

1987-01-01

A gas separation membrane has a dense separating layer about 10,000 Angstroms or less thick and a porous support layer 10 to 400 microns thick that is an integral unit with gradually and continuously decreasing pore size from the base of the support layer to the surface of the thin separating layer and is made from a casting solution comprising ethyl cellulose and ethyl cellulose-based blends, typically greater than 47.5 ethoxyl content ethyl cellulose blended with compatible second polymers, such as nitrocellulose. The polymer content of the casting solution is from about 10% to about 35% by weight of the total solution with up to about 50% of this polymer weight a compatible second polymer to the ethyl cellulose in a volatile solvent such as isopropanol, methylacetate, methanol, ethanol, and acetone. Typical nonsolvents for the casting solutions include water and formamide. The casting solution is cast in air from about zero to 10 seconds to allow the volatile solvent to evaporate and then quenched in a coagulation bath, typically water, at a temperature of 7.degree.-25.degree. C. and then air dried at ambient temperature, typically 10.degree.-30.degree. C.

Utilization of surface differences to improve dyeing properties of poly( m-phenylene isophthalamide) membranes

NASA Astrophysics Data System (ADS)

Ouyang, Shenshen; Wang, Tao; Zhong, Longgang; Wang, Shunli; Wang, Sheng

2018-06-01

Bulk poly( m-phenylene isophthalamide) (PMIA) can achieve flexibility upon dissolution by a LiCl/dimethylacetamide co-solvent, but remains hydrophobic despite the occasional emergence of cis amide groups providing a weak negative charge. In this study, based on the significant surface differences between PMIA membranes processed by nanofiber electrospinning and casting, a series of chemical analyses, in-situ Au nanoparticle depositions, and dye-adsorption experiments revealed that more cis-configuration amide groups appeared on the surface of the electrospun PMIA membrane than on that of the cast membrane. Based on this surface difference, a strategy was proposed to improve the dyeing properties of PMIA by reversibly changing the cis/trans configurations of electrospun and cast membranes. The reversible chain-segment switch mechanism is a novel method for tuning the macroscale properties of polymer materials based on inherent molecular characteristics.

Utilization of surface differences to improve dyeing properties of poly(m-phenylene isophthalamide) membranes

NASA Astrophysics Data System (ADS)

Ouyang, Shenshen; Wang, Tao; Zhong, Longgang; Wang, Shunli; Wang, Sheng

2018-05-01

Bulk poly(m-phenylene isophthalamide) (PMIA) can achieve flexibility upon dissolution by a LiCl/dimethylacetamide co-solvent, but remains hydrophobic despite the occasional emergence of cis amide groups providing a weak negative charge. In this study, based on the significant surface differences between PMIA membranes processed by nanofiber electrospinning and casting, a series of chemical analyses, in-situ Au nanoparticle depositions, and dye-adsorption experiments revealed that more cis-configuration amide groups appeared on the surface of the electrospun PMIA membrane than on that of the cast membrane. Based on this surface difference, a strategy was proposed to improve the dyeing properties of PMIA by reversibly changing the cis/trans configurations of electrospun and cast membranes. The reversible chain-segment switch mechanism is a novel method for tuning the macroscale properties of polymer materials based on inherent molecular characteristics.

The pristine graphene produced by liquid exfoliation of graphite in mixed solvent and its application to determination of dopamine.

PubMed

Zhang, Juan; Xu, Liao; Zhou, Bo; Zhu, Yinyan; Jiang, Xiaoqing

2018-03-01

The pristine graphene can be easily prepared in isopropanol-water mixture with salts as assistant via liquid-phase exfoliation method. The concentration of graphene dispersion reaches as high as 0.565 mg/mL. The graphene film prepared by drop-casting method shows an excellent electrical conductivity (7.095 × 10 4  S/m). Furthermore, an electrochemical biosensor based on the pristine graphene shows high selectivity and sensitivity for the determination of dopamine. The linear detection range for dopamine is 2.5-1500 μM with detection limit of 1.5 μM. This method provides a potential process for preparing high-quality graphene ready-to-use in low-boiling point solvent. Copyright © 2017 Elsevier Inc. All rights reserved.

Preparation of enhanced hydrophobic poly(L-lactide-co-ɛ-caprolactone) films surface and its blood compatibility

NASA Astrophysics Data System (ADS)

Kim, Seung Il; Lim, Jin Ik; Jung, Youngmee; Mun, Cho Hay; Kim, Ji Heung; Kim, Soo Hyun

2013-07-01

Hydrophobicity-enhanced poly(L-lactide-co-ɛ-caprolactone) (PLCL) (50:50) films were cast by using the solvent-nonsolvent casting method. PLCL (50:50) was synthesized by the well-known random copolymerization process and confirmed by 1H NMR analysis. The molecular weight of the synthesized PLCL was measured by gel permeation chromatography (GPC). Number-average (Mn), weight-average (Mw) molecular weights and polydispersity (Mw/Mn) were 7 × 104, 1.2 × 105, and 1.7, respectively. PLCL films were cast in vacuum condition with various nonsolvents and nonsolvent ratios. Tetrahydrofuran (THF) was used as the solvent and three different alcohols were used as the nonsolvent: methanol, ethanol, and isopropyl alcohol (IPA). Surface hydrophobicity was confirmed by water contact angle. The water contact angle was increased from 81° ± 2° to 107° ± 2°. Water contact angle was influenced by surface porosity and topography. The prepared film surfaces were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The change of crystalline property was characterized by X-ray diffraction (XRD). Platelet adhesion tests on the modified PLCL film surfaces were evaluated by platelet-rich plasma (PRP). The modified film surface exhibited enhanced hydrophobicity and reduced platelet adhesion ratio depending on the surface topography. One of the candidate products proposed as a potential blood compatible material showed a markedly reduced platelet adhesion property.

Understanding How Processing Additives Tune the Nanoscale Morphology of High Efficiency Organic Photovoltaic Blends: From Casting Solution to Spun-Cast Thin Film

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

Shao, Ming; Keum, Jong Kahk; Kumar, Rajeev

2014-08-26

Adding a small amount of a processing additive to the casting solution of photoactive 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, the effects of the processing additive diiodooctane (DIO) on the morphology of the established blend of PBDTTT-C-T polymer and the fullerene derivative PC71BM used for OPVs are investigated, starting in the casting solution and tracing the effects in spun-cast thin filmsmore » by using neutron/X-ray scattering, neutron reflectometry, and other characterization techniques. The results reveal that DIO has no observable effect on the structures of PBDTTT-C-T and PC71BM in solution; however, in the spun-cast films, it significantly promotes their molecular ordering and phase segregation, resulting in improved PCE. Thermodynamic analysis based on Flory-Huggins theory provides a rationale for the effects of DIO on different characteristics of phase segregation due to changes in concentration resulting from evaporation of the solvent and additive during film formation. Such information may help improve the rational design of ternary blends to more consistently achieve improved PCE for OPVs.« less

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

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

Shao, Ming; Keum, Jong Kahk; Kumar, Rajeev

2014-01-01

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. Themore » 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.« less

Poly/vinyl alcohol/ membranes for reverse osmosis

NASA Technical Reports Server (NTRS)

Katz, M. G.; Wydeven, T., Jr.

1981-01-01

A description is presented of the results of studies of the water and salt transport properties of PVA membranes, taking into account radiation crosslinked PVA membranes, diffusive salt permeability through PVA membranes, and heat treated PVA membranes. The experimental findings support an occurrence of independent water, and salt permeation processes. It is suggested that the salt permeation is governed by a solution-diffusion transport mechanism. The preparation of thin skinned, asymmetric PVA membranes is also discussed. The employed method has a certain similarity to the classical phase inversion method, which is widely applied in the casting of asymmetric reverse osmosis membranes. Instead of using a gelling bath composed of a nonsolvent for the membrane material and miscible with the solvent from which the membrane is cast, a 'complexing' bath is used, which is a solution of a complexing agent in water.

Development and characterization of a mucoadhesive sublingual formulation for pain control: extemporaneous oxycodone films in personalized therapy.

PubMed

Parodi, Brunella; Russo, Eleonora; Baldassari, Sara; Zuccari, Guendalina; Pastorino, Sara; Yan, Mengying; Neduri, Karthik; Caviglioli, Gabriele

2017-06-01

The aim of this work was the development of mucoadhesive sublingual films, prepared using a casting method, for the administration of oxycodone. A solvent casting method was employed to prepare the mucoadhesive films. A calibrated pipette was used to deposit single aliquots of different polymeric solutions on a polystyrene plate lid. Among the various tested polymers, hydroxypropylcellulose at low and medium molecular weight (HPC) and pectin at two different degrees of esterification (PC) were chosen for preparing solutions with good casting properties, capable of producing films suitable for mucosal application. The obtained films showed excellent drug content uniformity and stability and rapid drug release, which, at 8 min, ranged from 60% to 80%. All films presented satisfactory mucoadhesive and mechanical properties, also confirmed by a test on healthy volunteers, who did not experience irritation or mucosa damages. Pectin films based on pectin at lower degrees of esterification have been further evaluated to study the influence of two different amounts of drug on the physicochemical properties of the formulation. A slight reduction in elasticity has been observed in films containing a higher drug dose; nevertheless, the formulation maintained satisfactory flexibility and resistance to elongation. HPC and PC sublingual films, obtained by a simple casting method, could be proposed to realize personalized hospital pharmacy preparations on a small scale.

Production of permeable cellulose triacetate membranes

DOEpatents

Johnson, B.M.

1986-12-23

A phase inversion process for the preparation of cellulose triacetate (CTA) and regenerated cellulose membranes is disclosed. Such membranes are useful as supports for liquid membranes in facilitated transport processes, as microfiltration membranes, as dialysis or ultrafiltration membranes, and for the preparation of ion-selective electrodes. The process comprises the steps of preparing a casting solution of CTA in a solvent comprising a mixture of cyclohexanone and methylene chloride, casting a film from the casting solution, and immersing the cast film in a methanol bath. The resulting CTA membrane may then be hydrolyzed to regenerated cellulose using conventional techniques.

Production of permeable cellulose triacetate membranes

DOEpatents

Johnson, Bruce M.

1986-01-01

A phase inversion process for the preparation of cellulose triacetate (CTA) and regenerated cellulose membranes is disclosed. Such membranes are useful as supports for liquid membranes in facilitated transport processes, as microfiltration membranes, as dialysis or ultrafiltration membranes, and for the preparation of ion-selective electrodes. The process comprises the steps of preparing a casting solution of CTA in a solvent comprising a mixture of cyclohexanone and methylene chloride, casting a film from the casting solution, and immersing the cast film in a methanol bath. The resulting CTA membrane may then be hydrolyzed to regenerated cellulose using conventional techniques.

Solutocapillary Convection Effects on Polymeric Membrane Morphology

NASA Technical Reports Server (NTRS)

Krantz, William B.; Todd, Paul W.; Kinagurthu, Sanjay

1996-01-01

Macro voids are undesirable large pores in membranes used for purification. They form when membranes are cast as thin films on a smooth surface by evaporating solvent (acetone) from a polymer solution. There are two un-tested hypotheses explaining the growth of macro voids. One states that diffusion of the non-solvent (water) is solely responsible, while the other states that solutocapillary convection is the primary cause of macro void growth. Solutocapillary convection is flow-caused by a concentration induced surface-tension gradient. Macrovoid growth in the former hypothesis is gravity independent, while in the latter it is opposed by gravity. To distinguish between these two hypotheses, experiments were designed to cast membranes in zero-gravity. A semi-automated apparatus was designed and built for casting membranes during the 20 secs of zero-g time available in parabolic aircraft flight such as NASA's KC-135. The phase changes were monitored optically, and membrane morphology was evaluated by scanning electron microscopy (SEM). These studies appear to be the first quantitative studies of membrane casting in micro-gravity which incorporate real-time data acquisition. Morphological studies of membranes cast at 0, 1, and 1.8 g revealed the presence of numerous, sparse and no macrovoids respectively. These results are consistent with the predictions of the solutocapillary hypothesis of macrovoid growth.

Fire-Retardant Decorative Inks For Aircraft Interiors

NASA Technical Reports Server (NTRS)

Kourtides, D. A.; Nir, Z.; Mikroyannidis, J. A.

1988-01-01

Report describes testing of commercial and experimental fire retardants for incorporation into acrylic printing inks used on aircraft-interior sandwich panels. Films of acrylic ink containing fire-retardant additives prepared by casting on glass plates. Solvent evaporated in vacuum, cast films cured at 80 to 100 degree C for 30 minutes in air-circulating oven. Thermochemical properties of films examined by thermogravimetric analysis and differential scanning calorimetry (DSC). Samples of inks cast on sheets of polyvinylfloride (PVF), and their limiting oxygen indices and smoke evolution measured.

Synthesis and characterization of sulfonated poly ether ether ketone (sPEEK) membranes for low temperature fuel cells

NASA Astrophysics Data System (ADS)

Ali, Mawlood Maajal; Rizvi, S. J. A.; Azam, Ameer

2018-05-01

Poly ether ether ketone (PEEK) was sulfonated with 1.0 M sulphuric acid for varying durations to have various degrees of sulfonation (DS) from 43 to 55%. The FT-IR spectra confirmed the successful sulfonation of PEEK. The sulfonated PEEK (sPEEK) membranes were prepared by a solvent casting method using dimethylacetamide (DMAc) as solvent and upon drying the membranes were characterized. The DS% and ion exchange capacity (IEC) were determined by a back titration method. The IEC and DS of sPEEK was found to increase with the increment of sulfonation reaction time. Water uptake also increased with increase in the DS. The Thermogravimetric (TGA) curves revealed poor thermal stability of sPEEK. The proton conductivity of sPEEK membrane was found to considerably better with degree of sulfonation for fuel cell application.

Studies on wettability of polypropylene/methyl-silicone composite film and polypropylene monolithic material.

PubMed

Hou, Weixin; Mu, Bo; Wang, Qihua

2008-11-01

A polypropylene/methyl-silicone superhydrophobic surface was prepared using a simple casting method. Varying the ratio of polypropylene and methyl-silicone results in different surface microstructure. The wetting behavior of the as-prepared surface was investigated. A polypropylene monolithic material was also prepared. Its superhydrophobicity still retains when the material was cut or abraded. The as-prepared material can also be used to separate some organic solvents from water.

Effects of solvent on the solution properties, structural characteristics and properties of silk sericin.

PubMed

Jo, Yoon Nam; Um, In Chul

2015-07-01

Sericin films have attracted much attention from researchers in biomedical and cosmetic fields because of its unique properties, including good cytocompatibility and its promotion of wound healing. However, poor mechanical properties of sericin films have restricted its application in these fields. In this study, a new solvent, formic acid, was used to fabricate sericin solutions and films. The effects of formic acid on the structural characteristics and mechanical properties of the sericin solutions and films were examined and compared with water. The sericin/formic acid solution showed fewer aggregated sericin molecules, resulting in a lower turbidity than that of the sericin/water solution. In addition, the gelation of the sericin solution was retarded in formic acid compared to that of water. Sericin films cast from the formic acid solution exhibited a much higher crystallinity index than that produced from water. The tensile strength and elongation of the sericin films cast from the formic acid solution were more than double that of the sericin films cast from water. It is expected that the more stable sericin solution and high-crystallinity sericin films, which have significantly improved mechanical properties, produced by using formic acid as the solvent could be utilized in biomedical and cosmetic applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Adsorption of dispersants on zirconia powder in tape-casting slip compositions

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

Richards, V.L. II

This paper reports the determination of adsorption isotherms for menhaden fish oil and glycerol trioleate on doped zirconia powder in solvents composed of 70% methyl ethyl ketone (MEK) and 30% ethanol. In order to approach tape-casting zirconia on a sound technical basis, the correspondence of slip viscosities and tape sintered densities to the adsorption isotherms was studied.

Arrays of hollow out-of-plane microneedles made by metal electrodeposition onto solvent cast conductive polymer structures

NASA Astrophysics Data System (ADS)

Mansoor, I.; Liu, Y.; Häfeli, U. O.; Stoeber, B.

2013-08-01

Transdermal drug delivery using microneedles is a technique to potentially replace hypodermic needles for injection of many vaccines and drugs. Fabrication of hollow metallic microneedles so far has been associated with time-consuming steps that restrict batch production of these devices. Here, we are presenting a novel method for making metallic microneedles with any desired height, spacing, and lumen size. In our process, we use solvent casting to coat a mold, which contains an array of pillars, with a conductive polymer composite layer. The conductive layer is then used as a seed layer in a metal electrodeposition process. To characterize the process, the conductivity of the polymer composite with respect to different filler concentrations was investigated. In addition, plasma etching of the polymer was characterized. The electroplating process was also studied further to control the thickness of the microneedle array plate. The strength of the microneedle devices was evaluated through a series of compression tests, while their performance for transdermal drug delivery was tested by injection of 2.28 µm fluorescent microspheres into animal skin. The fabricated metallic microneedles seem appropriate for subcutaneous delivery of drugs and microspheres.

Stable powders made from photosensitive polycrystalline complexes of heterocyclic monomers and their polymers

NASA Technical Reports Server (NTRS)

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dalibor (Inventor)

1999-01-01

The present invention relates to a low electronic conductivity polymer composition having well dispersed metal granules, a stable powder made from photosensitive polycrystalline complexes of pyrrole, or its substituted derivatives and silver cations for making the polymer composition, and methods of forming the stable powder and polymer composition, respectively. A polycrystalline complex of silver and a monomer, such as pyrrole, its substituted derivatives or combinations thereof, is precipitated in the form of a stable photosensitive powder upon addition of the monomer to a solvent solution, such as toluene containing an electron acceptor. The photosensitive powder can be stored in the dark until needed. The powder may be dissolved in a solvent, cast onto a substrate and photopolymerized.

Benzimidazole Based Aerogel Materials

NASA Technical Reports Server (NTRS)

Rhine, Wendell E. (Inventor); Mihalcik, David (Inventor)

2016-01-01

The present invention provides aerogel materials based on imidazoles and polyimidazoles. The polyimidazole based aerogel materials can be thermally stable up to 500 C or more, and can be carbonized to produce a carbon aerogel having a char yield of 60% or more, specifically 70% or more. The present invention also provides methods of producing polyimidazole based aerogel materials by reacting at least one monomer in a suitable solvent to form a polybenzimidazole gel precursor solution, casting the polybenzimidazole gel precursor solution into a fiber reinforcement phase, allowing the at least one gel precursor in the precursor solution to transition into a gel material, and drying the gel materials to remove at least a portion of the solvent, to obtain an polybenzimidazole-based aerogel material.

A Solvent-Vapor Approach toward the Control of Block Ionomer Morphologies

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

Mineart, Kenneth P.; Lee, Byeongdu; Spontak, Richard J.

Sulfonated block ionomers possess advantageous properties for a wide range of diverse applications such as desalination membranes, fuel cells, electroactive media, and photovoltaic devices. Unfortunately, their inherently high incompatibilities and glass transition temperatures e ff ectively prevent the use of thermal annealing, routinely employed to re fi ne the morphologies of nonionic block copolymers. An alternative approach is therefore required to promote morphological equilibration in block ionomers. The present study explores the morphological characteristics of midblock- sulfonated pentablock ionomers (SBIs) di ff ering in their degree of sulfonation (DOS) and cast from solution followed by solvent-vapor annealing (SVA). Transmission electronmore » microscopy con fi rms that fi lms deposited from di ff erent solvent systems form nonequilibrium morphologies due to solvent-regulated self-assembly and drying. A series of SVA tests performed with solvents varying in polarity reveals that exposing cast fi lms to tetrahydrofuran (THF) vapor for at least 2 h constitutes the most e ff ective SVA protocol, yielding the anticipated equilibrium morphology. That is, three SBI grades subjected to THF-SVA self-assemble into well-ordered lamellae wherein the increase in DOS is accompanied by an increase in lamellar periodicity, as measured by small-angle X-ray scattering.« less

Multicomponent membranes

DOEpatents

Kulprathipanja, Santi; Kulkarni, Sudhir S.; Funk, Edward W.

1988-01-01

A multicomponent membrane which may be used for separating various components which are present in a fluid feed mixture comprises a mixture of a plasticizer such as a glycol and an organic polymer cast upon a porous organic polymer support. The membrane may be prepared by casting an emulsion or a solution of the plasticizer and polymer on the porous support, evaporating the solvent and recovering the membrane after curing.

Method for producing high dielectric strength microvalves

DOEpatents

Kirby, Brian J [San Francisco, CA; Reichmuth, David S [Oakland, CA; Shepodd, Timothy J [Livermore, CA

2006-04-04

A microvalve having a cast-in-place and lithographically shaped mobile, polymer monolith for fluid flow control in microfluidic devices and method of manufacture. The microvalve contains a porous fluorinated polymer monolithic element whose pores are filled with an electrically insulating, high dielectric strength fluid, typically a perfluorinated liquid. This combination provides a microvalve that combines high dielectric strength with extremely low electrical conductivity. These microvalves have been shown to have resistivities of at least 100 G.OMEGA. and are compatible with solvents such as water at a pH between 2.7 and 9.0, 1-1 propanol, acetonitrile, and acetone.

Cellulose triacetate, thin film dielectric capacitor

NASA Technical Reports Server (NTRS)

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

1995-01-01

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.

Cellulose triacetate, thin film dielectric capacitor

NASA Technical Reports Server (NTRS)

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

1993-01-01

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.

Linear regression models for solvent accessibility prediction in proteins.

PubMed

Wagner, Michael; Adamczak, Rafał; Porollo, Aleksey; Meller, Jarosław

2005-04-01

The relative solvent accessibility (RSA) of an amino acid residue in a protein structure is a real number that represents the solvent exposed surface area of this residue in relative terms. The problem of predicting the RSA from the primary amino acid sequence can therefore be cast as a regression problem. Nevertheless, RSA prediction has so far typically been cast as a classification problem. Consequently, various machine learning techniques have been used within the classification framework to predict whether a given amino acid exceeds some (arbitrary) RSA threshold and would thus be predicted to be "exposed," as opposed to "buried." We have recently developed novel methods for RSA prediction using nonlinear regression techniques which provide accurate estimates of the real-valued RSA and outperform classification-based approaches with respect to commonly used two-class projections. However, while their performance seems to provide a significant improvement over previously published approaches, these Neural Network (NN) based methods are computationally expensive to train and involve several thousand parameters. In this work, we develop alternative regression models for RSA prediction which are computationally much less expensive, involve orders-of-magnitude fewer parameters, and are still competitive in terms of prediction quality. In particular, we investigate several regression models for RSA prediction using linear L1-support vector regression (SVR) approaches as well as standard linear least squares (LS) regression. Using rigorously derived validation sets of protein structures and extensive cross-validation analysis, we compare the performance of the SVR with that of LS regression and NN-based methods. In particular, we show that the flexibility of the SVR (as encoded by metaparameters such as the error insensitivity and the error penalization terms) can be very beneficial to optimize the prediction accuracy for buried residues. We conclude that the simple and computationally much more efficient linear SVR performs comparably to nonlinear models and thus can be used in order to facilitate further attempts to design more accurate RSA prediction methods, with applications to fold recognition and de novo protein structure prediction methods.

Nonaqueous slip casting of YBa2Cu3O(7-x) superconductive ceramics. Ph.D. Thesis - 1993

NASA Technical Reports Server (NTRS)

Hooker, Matthew W.; Taylor, Theodore D.

1994-01-01

This study investigates the slip casting of YBa2Cu3O(7-x) powders using nonaqueous carrier liquids and fired ceramic molds. The parameters of the process examined here include the rheological properties of YBa2Cu3O(7-x) powder dispersed in various solvent/dispersant systems, the combination of nonaqueous slips with fired ceramic molds to form the superconductive ceramics, the process-property relationships using a four-factor factorial experiment, and the applicability of magnetic fields to align the YBa2Cu3O(7-x) grains during the casting process.

Microstructurally tailored ceramics for advanced energy applications by thermoreversible gelcasting

NASA Astrophysics Data System (ADS)

Shanti, Noah Omar

Thermoreversible gelcasting (TRG) is an advantageous technique for rapidly producing bulk, net-shape ceramics and laminates. In this method, ceramic powder is suspended in warm acrylate triblock copolymer/alcohol solutions that reversibly gel upon cooling by the formation of endblock aggregates, to produce slurries which are cast into molds. Gel properties can be tailored by controlling the endblock and midblock lengths of the copolymer network-former and selecting an appropriate alcohol solvent. This research focuses on expanding and improving TRG techniques, focusing specifically on advanced energy applications including the solid oxide fuel cell (SOFC). Rapid drying of filled gels can lead to warping and cracking caused by high differential capillary stresses. A new drying technique using concentrated, alcohol-based solutions as liquid desiccants (LDs) to greatly reduce warping is introduced. The optimal LD is a poly(tert-butyl acrylate)/isopropyl alcohol solution with 5 mol% tert-butyl acrylate units. Alcohol emissions during drying are completely eliminated by combining initial drying in an LD with final stage drying in a vacuum oven having an in-line solvent trap. Porous ceramics are important structures for many applications, including SOFCs. Pore network geometries are tailored by the addition of fugitive fillers to TRG slurries. Uniform spherical, bimodal spherical and uniform fibrous fillers are used. Three-dimensional pore structures are visualized by X-ray computed tomography, allowing for direct measurements of physical parameters such as concentration and morphology as well as transport properties such as tortuosity. Tortuosity values as low as 1.52 are achieved when 60 vol% of solids are uniform spherical filler. Functionally graded laminates with layers ranging from 10 mum to > 1 mm thick are produced with a new technique that combines TRG with tape casting. Gels used for bulk casting are not suitable for use with tape casting, and appropriate base gels are selected for this technique. Each layer is cast in a single pass, and the layers are directly laminated. The anode support, anode functional layer, and electrolyte of anode-supported SOFCs are produced using this technique. The performance of SOFCs produced this way is not yet equal to that of traditionally processed cells, but shows the promise of this technique.

Supramolecular Assembly of Tripodal Trisamides

NASA Astrophysics Data System (ADS)

Feng, Li

2010-03-01

A series of tripodal trisamide compounds have been synthesized from tris(2-aminoethyl)amine (TREN) by condensation with different acid chlorides. Gelation of organic solvents with these compounds was investigated as a function of concentration and solvent solubility parameter. Compounds made with linear acid chlorides were poor gelators. A gelator made with 2-ethylbutyryl chloride (TREN-EB) was an excellent gelator for many organic solvents. It was found that the minimum gelation concentration of TREN-EB increased with increasing solubility parameter of the solvent. Thin films samples were prepared by spin-coating mixtures of TREN-EB and a poly(acrylate). Scanning force microscopy measurements showed that TREN-EB formed nanofibrillar network structures. In addition a dependence of the network morphology on the casting solvent was found.

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

PubMed

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

2014-05-01

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.

Method of preparation of removable syntactic foam

DOEpatents

Arnold, C. Jr.; Derzon, D.K.; Nelson, J.S.; Rand, P.B.

1995-07-11

Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced by this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications. 1 fig.

Method of preparation of removable syntactic foam

DOEpatents

Arnold, Jr., Charles; Derzon, Dora K.; Nelson, Jill S.; Rand, Peter B.

1995-01-01

Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced by this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications.

Fabrication and Optimization of Carbon Nanomaterial-Based Lithium-Ion Battery Anodes

DTIC Science & Technology

2012-03-01

preparation setup under the fume hood with NMP solvent, glass pipette with dispenser, and the ball milled powder mixture containing LiFePO4 , acetylene...minutes. ............................................................................. 18 Figure 12. (a) LiFePO4 slurry applied on foil current collector...and (b) LiFePO4 slurry casted with applicator and (c) LiFePO4 casted (From [15])....... 18 Figure 13. MTI disc cutter used to cut individual

Predicting the optimal process window for the coating of single-crystalline organic films with mobilities exceeding 7 cm2/Vs.

NASA Astrophysics Data System (ADS)

Janneck, Robby; Vercesi, Federico; Heremans, Paul; Genoe, Jan; Rolin, Cedric

2016-09-01

Organic thin film transistors (OTFTs) based on single crystalline thin films of organic semiconductors have seen considerable development in the recent years. The most successful method for the fabrication of single crystalline films are solution-based meniscus guided coating techniques such as dip-coating, solution shearing or zone casting. These upscalable methods enable rapid and efficient film formation without additional processing steps. The single-crystalline film quality is strongly dependent on solvent choice, substrate temperature and coating speed. So far, however, process optimization has been conducted by trial and error methods, involving, for example, the variation of coating speeds over several orders of magnitude. Through a systematic study of solvent phase change dynamics in the meniscus region, we develop a theoretical framework that links the optimal coating speed to the solvent choice and the substrate temperature. In this way, we can accurately predict an optimal processing window, enabling fast process optimization. Our approach is verified through systematic OTFT fabrication based on films grown with different semiconductors, solvents and substrate temperatures. The use of best predicted coating speeds delivers state of the art devices. In the case of C8BTBT, OTFTs show well-behaved characteristics with mobilities up to 7 cm2/Vs and onset voltages close to 0 V. Our approach also explains well optimal recipes published in the literature. This route considerably accelerates parameter screening for all meniscus guided coating techniques and unveils the physics of single crystalline film formation.

Elongated phase separation domains in spin-cast polymer blend thin films characterized using a panoramic image.

PubMed

Zhang, Hong; Okamura, Yosuke

2018-02-14

Polymer thin films with micro/nano-structures can be prepared by a solvent evaporation induced phase separation process via spin-casting a polymer blend, where the elongated phase separation domains are always inevitable. The striation defect, as a thickness nonunifomity in spin-cast films, is generally coexistent with the elongated domains. Herein, the morphologies of polymer blend thin films are recorded from the spin-cast center to the edge in a panoramic view. The elongated domains are inclined to appear at the ridge regions of striations with increasing radial distance and align radially, exhibiting a coupling between the phase separation morphology and the striation defect that may exist. We demonstrate that the formation of elongated domains is not attributed to shape deformation, but is accomplished in situ. A possible model to describe the initiation and evolution of the polymer blend phase separation morphology during spin-casting is proposed.

Hydroxyapatite scaffolds processed using a TBA-based freeze-gel casting/polymer sponge technique.

PubMed

Yang, Tae Young; Lee, Jung Min; Yoon, Seog Young; Park, Hong Chae

2010-05-01

A novel freeze-gel casting/polymer sponge technique has been introduced to fabricate porous hydroxyapatite scaffolds with controlled "designer" pore structures and improved compressive strength for bone tissue engineering applications. Tertiary-butyl alcohol (TBA) was used as a solvent in this work. The merits of each production process, freeze casting, gel casting, and polymer sponge route were characterized by the sintered microstructure and mechanical strength. A reticulated structure with large pore size of 180-360 microm, which formed on burn-out of polyurethane foam, consisted of the strut with highly interconnected, unidirectional, long pore channels (approximately 4.5 microm in dia.) by evaporation of frozen TBA produced in freeze casting together with the dense inner walls with a few, isolated fine pores (<2 microm) by gel casting. The sintered porosity and pore size generally behaved in an opposite manner to the solid loading, i.e., a high solid loading gave low porosity and small pore size, and a thickening of the strut cross section, thus leading to higher compressive strengths.

Surface quality and microstructure of low-vacuum sintered orthodontic bracket 17-4 PH stainless steel fabricated by MIM process

NASA Astrophysics Data System (ADS)

Suharno, Bambang; Suharno, Lingga Pradinda; Saputro, Hantoro Restucondro; Irawan, Bambang; Prasetyadi, Tjokro; Ferdian, Deni; Supriyadi, Sugeng

2018-02-01

Surface roughness and microstructure play important role on orthodontic bracket quality. Therefore, orthodontic brackets need to have smooth surface roughness to reduce the friction and bacterial adhesion. Microstructure of orthodontic brackets also determine the mechanical properties and corrosion resistance. There are two methods to produce orthodontic bracket, investment casting and metal injection molding. The purpose of this study is to observe the surface roughness and microstructure of orthodontic bracket which were made from two different fabrication methods. To produce orthodontic bracket with metal injection molding method, 17-4 PH stainless steel feedstock was injected to the orthodontic bracket mold using injection molding machine. After injection, the binder was eliminated with solvent and thermal debinding. Solvent debinding process was conducted with hexane at 50 °C on magnetic stirrer for 1.5 hours. Thermal debinding process was conducted at 510 °C with 0.5 °C/min heat rate and 120 min holding time. Hereafter, sintering process were performed with vacuum tube furnace at 1360 °C with heat rate 5 °C/min and 90 min holding time in low vacuum atmosphere. To produce orthodontic bracket with investment casting method, the wax was injected into the mold then the wax pattern was arranged into the tree form. The tree form was then dipped into ceramic slurry and allowed to harden, the ceramic slurry has a thickness in the region of 10 mm. The ceramic mold was then heated at a temperature of over than 1100°C to strengthen the ceramic mold and to remove the remaining wax. After that, the molten 17-4 PH stainless steel was poured into the ceramic mold at a temperature of over 1600°C. The natural cooling process was carried out at temperature of 25°C, after which the ceramic mold was broken away. Then, the orthodontic bracket was cut from the tree form. The results show that the orthodontic bracket which were made with investment casting fabrication method have low porosity, high density, and there is no indication of secondary phase on the microstructure. However, it has rough brackets surface. Whereas, the production of orthodontic brackets using metal injection molding method resulted in better surface roughness. But, it has relatively high porosity, presence of another phase on the microstructure, and low density.

Stronger Fire-Resistant Epoxies

NASA Technical Reports Server (NTRS)

Fohlen, George M.; Parker, John A.; Kumar, Devendra

1988-01-01

New curing agent improves mechanical properties and works at lower temperature. Use of aminophenoxycyclotriphosphazene curing agents yields stronger, more heat- and fire-resistant epoxy resins. Used with solvent if necessary for coating fabrics or casting films.

Preparation and characterization of shape memory polymer scaffolds via solvent casting/particulate leaching.

PubMed

De Nardo, Luigi; Bertoldi, Serena; Cigada, Alberto; Tanzi, Maria Cristina; Haugen, Håvard Jostein; Farè, Silvia

2012-09-27

Porous Shape Memory Polymers (SMPs) are ideal candidates for the fabrication of defect fillers, able to support tissue regeneration via minimally invasive approaches. In this regard, control of pore size, shape and interconnection is required to achieve adequate nutrient transport and cell ingrowth. Here, we assessed the feasibility of the preparation of SMP porous structures and characterized their chemico-physical properties and in vitro cell response. SMP scaffolds were obtained via solvent casting/particulate leaching of gelatin microspheres, prepared via oil/water emulsion. A solution of commercial polyether-urethane (MM-4520, Mitsubishi Heavy Industries) was cast on compacted microspheres and leached-off after polymer solvent evaporation. The obtained structures were characterized in terms of morphology (SEM and micro-CT), thermo-mechanical properties (DMTA), shape recovery behavior in compression mode, and in vitro cytocompatibility (MG63 Osteoblast-like cell line). The fabrication process enabled easy control of scaffold morphology, pore size, and pore shape by varying the gelatin microsphere morphology. Homogeneous spherical and interconnected pores have been achieved together with the preservation of shape memory ability, with recovery rate up to 90%. Regardless of pore dimensions, MG63 cells were observed adhering and spreading onto the inner surface of the scaffolds obtained for up to seven days of static in vitro tests. A new class of SMP porous structures has been obtained and tested in vitro: according to these preliminary results reported, SMP scaffolds can be further exploited in the design of a new class of implantable devices.

Water dispersible microbicidal cellulose acetate phthalate film

PubMed Central

Neurath, A Robert; Strick, Nathan; Li, Yun-Yao

2003-01-01

Background Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production. Methods CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined. Results The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold. Conclusions Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP. PMID:14617380

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

Tiwari, Pragya; Srivastava, A. K.; Khattak, B. Q.

Polymethyl methacrylate (PMMA) is characterized for electron beam interactions in the resist layer in lithographic applications. PMMA thin films (free standing) were prepared by solvent casting method. These films were irradiated with 30keV electron beam at different doses. Structural and chemical properties of the films were studied by means of X-ray diffraction and Fourier transform infra-red (FTIR) spectroscopy The XRD results showed that the amorphization increases with electron beam irradiation dose. FTIR spectroscopic analysis reveals that electron beam irradiation promotes the scission of carbonyl group and depletes hydrogen and converts polymeric structure into hydrogen depleted carbon network.

Solvent-resistant microporous polymide membranes

DOEpatents

Miller, W.K.; McCray, S.B.; Friesen, D.T.

1998-03-10

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

Solvent-resistant microporous polymide membranes

DOEpatents

Miller, Warren K.; McCray, Scott B.; Friesen, Dwayne T.

1998-01-01

An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

FerriCast: a macrocyclic photocage for Fe3+.

PubMed

Kennedy, Daniel P; Incarvito, Christopher D; Burdette, Shawn C

2010-02-01

The non-siderophoric Fe(3+) photocage FerriCast (4,5-dimethoxy-2-nitrophenyl)-[4-(1-oxa-4,10-dithia-7-aza-cyclododec-7-yl)phenyl] methanol (2) has been prepared in high yield using an optimized two-step reaction sequence that utilizes a trimethylsilyl trifluoromethanesulfonate (TMSOTf) assisted electrophilic aromatic substitution as the key synthetic step. Spectrophotometric assessment of Fe(3+) binding to FerriCast revealed a binding stoichiometry and metal ion affinity dependent on the nature of the counterion. Exposure of FerriCast to 350 nm light initiates a photoreaction that converts FerriCast into FerriUnc (4,5-dimethoxy-2-nitrosophenyl)-[4-(1-oxa-4,10-dithia-7-aza-cyclododec-7-yl)phenyl]-methanone), which binds Fe(3+) less strongly owing to resonance delocalization of the anilino lone pair into the benzophenone pi-system. The release of Fe(3+) upon photolysis of FerriCast also was evaluated using a previously reported turn-on fluorescent sensor that utilizes the same macrocyclic ligand (4-(1-oxa-4,10-dithia-7-aza-cyclododec-7-yl)phenyl, AT(2)12C4). In contrast to the original reports on AT(2)12C4-based Fe(3+) sensors, FerriCast does not interact with ferric iron in aqueous solution. Introduction of oxygen containing solvents (MeOH, H(2)O, DMSO, MES, and phosphate buffers) to CH(3)CN solutions of metalated FerriCast lead to rapid decomplexation as measured by UV-visible spectroscopy. Further investigations contradicted the published conclusions on the aqueous coordination chemistry of AT(2)12C4, but also confirmed the unique and unexpected selectivity of the macrocycle for Fe(3+) in nonaqueous solvents. The crystallographic analysis of [Cu(AT(2)12C4)Cl](+) provides a rare example of a bifurcated hydrogen bond, and evidence for redox chemistry with the ligand. Spectrophotometric analysis of the model ligand with redox active metal ions provide evidence for AT(2)12C4(*+), a quasi-stable species the presence of which suggests caution should be taken when evaluating the interaction of aniline-containing systems with redox active metal ions.

Growth of alkyl-monosubstituted thiophene/phenylene co-oligomer crystals and their device application

NASA Astrophysics Data System (ADS)

Sugahara, Kazuchika; Nakagawa, Takao; Hirase, Ryuji; Katagiri, Toshifumi; Inada, Yuhi; Yamao, Takeshi; Hotta, Shu

2018-04-01

We synthesized a novel small-molecule organic semiconductor, which is soluble in organic solvents at room temperature under normal pressure. We demonstrated that its high-quality crystalline films can be directly grown on substrates using various solution techniques such as solution casting, slow evaporation, and edge casting. We applied crystals to FETs with a bottom- or top-contact configuration, revealing that the carrier mobility ranged from ˜10-4 to ˜10-2 cm2 V-1 s-1.

Reflective Self-Metallizing Polyimide Films

NASA Technical Reports Server (NTRS)

Thompson, David W. (Inventor); Caplan, Maggie L. (Inventor); St.Clair, Anne (Inventor)

1997-01-01

A silver organic complex, such as silver acetate, is solubilized in a polyamic acid resin or soluble polyimide solution using a suitable solvent such as hexafluoroacetyl acetone. The mixture is stable and can be applied to both flat and contoured surfaces. Application can be performed by casting, dip-coating, spraying, or other suitable techniques. In addition, the mixture can be cast or extruded as a polyimide film which is not applied to an underlying substrate. Upon curing, a flexible silver coated polyimide film is produced.

Method of preparation of removable syntactic foam

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

Arnold, C. Jr.; Derzon, D.K.; Nelson, J.S.

1995-07-11

Easily removable, environmentally safe, low-density, syntactic foams are disclosed which are prepared by mixing insoluble microballoons with a solution of water and/or alcohol-soluble polymer to produce a pourable slurry, optionally vacuum filtering the slurry in varying degrees to remove unwanted solvent and solute polymer, and drying to remove residual solvent. The properties of the foams can be controlled by the concentration and physical properties of the polymer, and by the size and properties of the microballoons. The suggested solute polymers are non-toxic and soluble in environmentally safe solvents such as water or low-molecular weight alcohols. The syntactic foams produced bymore » this process are particularly useful in those applications where ease of removability is beneficial, and could find use in packaging recoverable electronic components, in drilling and mining applications, in building trades, in art works, in the entertainment industry for special effects, in manufacturing as temporary fixtures, in agriculture as temporary supports and containers and for delivery of fertilizer, in medicine as casts and splints, as temporary thermal barriers, as temporary protective covers for fragile objects, as filters for particulate matter, which matter may be easily recovered upon exposure to a solvent, as in-situ valves (for one-time use) which go from maximum to minimum impedance when solvent flows through, and for the automatic opening or closing of spring-loaded, mechanical switches upon exposure to a solvent, among other applications. 1 fig.« less

Stress evolution in solidifying coatings

NASA Astrophysics Data System (ADS)

Payne, Jason Alan

The goal of this study is to measure, in situ, and control the evolution of stress in liquid applied coatings. In past studies, the stress in a coating was determined after processing (i.e., drying or curing). However, by observing a coating during drying or curing, the effects of processing variables (e.g., temperature, relative humidity, composition, etc.) on the stress state can be better determined. To meet the project goal, two controlled environment stress measurement devices, based on a cantilever deflection measurement principle, were constructed. Stress evolution experiments were completed for a number of coating systems including: solvent-cast homopolymers, tape-cast ceramics, aqueous gelatins, and radiation-cured multifunctional acrylates. In the majority of systems studied here, the final stresses were independent of coating thickness and solution concentration. Typical stress magnitudes for solvent-cast polymers ranged from zero to 18 MPa depending upon the pure polymer glass transition temperature (Tsb{g}), the solvent volatility, and additional coating components, such as plasticizers. Similar magnitudes and dependencies were observed in tape-cast ceramic layers. Stresses in gelatin coatings reached 50 MPa (due to the high Tsb{g} of the gelatin) and were highly dependent upon drying temperature and relative humidity. In contrast to the aforementioned coatings, stress in UV-cured tri- and tetrafunctional acrylate systems showed a large thickness dependence. For these materials, stress evolution rate and magnitude increased with photoinitiator concentration and with light intensity. Somewhat unexpectedly, larger monomer functionality led to greater stresses at faster rates even though the overall conversion fell. The stress magnitude and evolution rate at any stage in the solidification process are the result of a competition between shrinkage (due to drying, curing, etc.) and stress relaxation. A firm understanding of the mechanical, the thermal, and the microstructural properties of a coating is therefore necessary to properly study stress effects. Hence, observations from dynamic mechanical analysis, indentation, infrared spectroscopy, and optical microscopy were also studied in order to correlate coating properties (mechanical, thermal, and structural) to measured stresses.

Novel Processing of a Poly(phenyleneoxide) - b –Poly(vinylbenzyltrimethylammonium) Copolymer Anion Exchange Membrane; The Effect On Mechanical And Transport Properties

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

Pandey, Tara P.; Seifert, Soenke; Yang, Yating

2016-12-01

A poly(2,6 dimethyl 1,4-phenylene oxide)-b-poly(vinyl benzyl) chloride copolymer membranes was processed by solvent casting followed by melt pressing (SCMP) to provide uniformly thin films, 25 +/- 5 mu m, with improved conductivity, mechanical strength, water uptake, dimensional swelling, and chemical stability under 1 M KOH and 80 degrees C. These properties depended strongly on the length of the melt-pressing time. The solvent cast membranes melt pressing time was optimized to provided highly conductive membranes (high OH- conductivity of 75 +/- 25 mS cm(-1) for an IEC of 1.8 mmol g(-1) at room temperature in water). Membranes that were only solventmore » cast and not melt-pressed swelled excessively and had insufficient mechanical integrity for detailed study. When the copolymer powder was melt pressed (without prior solvent casting) at 240 degrees C and ca. 30 MPa for 20 minutes, membranes with high mechanical strength (tensile stress at break of 32 +/- 6 MPa at 25% RH and 29 +/- 3 MPa when 95% RH at 60 degrees C), high conductivity (Cl conductivity of 80 mS/cm at 90 degrees C and 95% RH), and lower water uptake were formed. However, melt pressing alone did not give larger then 5 cm x 5 cm area films, homogeneously thin (< 60 mu m), or mechanical defect-free membranes. The SCMP membranes were uniformly thin, and thermally crosslinked. The mass loss via dehydrochlorination indicated by TGA and elemental analysis confirmed the crosslinking via thermal melt pressing. The SCMP membranes thickness could be reduced by more than 50% (25 +/- 5 mu m) compared to melt pressing alone, and the Cl conductivity increased by 44% at 90 degrees C and 95% RH. The tensile stress at break of the SCMP membranes, however, was reduced by 50% at 25% RH.« less

Influence of purified multiwalled carbon nanotubes on the mechanical and morphological behavior in poly (L-lactic acid) matrix.

PubMed

Leal, C V; Martinez, D S T; Más, B A; Alves, O L; Duek, E A R

2016-06-01

Poly (L-latic acid) (PLLA) is a bioresorbable polymer widely used as a biomaterial, but its fragility can limit its use. An alternative is to produce polymer nanocomposites, which can enhance the mechanical properties of polymeric matrix, resulting in a material with differentiated properties. In this work, PLLA based nanocomposites containing 0.25, 0.5 and 1.0wt% of purified multiwalled carbon nanotubes (p-MWCNTs) were prepared by the solvent casting method. The morphology and mechanical properties results show an improvement in strain at break for 0.25 and 0.5wt% p-MWCNTs and an increase in stiffness and elastic modulus for all compositions. Nanocomposites presented a p-MWCNTs agglomeration; however, there was a good stress transfer between PLLA and p-MWCNTs, which was confirmed by the increase in the hardness and elastic modulus. Atomic force microscopy analysis indicated an increase in roughness after nanotube addition. The in vitro biological study showed that PLLA/p-MWCNTs nanocomposites are cytocompatible with osteoblasts cells. The capacity of PLLA nanocomposites to stimulate osteogenesis was investigated by alkaline phosphatase (ALP) activity assay. Higher ALP activity was found on osteoblasts cultured on nanocomposites with 0.25 and 0.5wt% p-MWCNT compared to neat PLLA, confirming that PLLA cytocompatibility was improved on these compositions. Finally, our results showed that by a simple and inexpensive solvent casting method, it is possible to manufacture biofunctional nanocomposites devices with potential for orthopedic applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

Polymer blend of PLA/PHBV based bionanocomposites reinforced with nanocrystalline cellulose for potential application as packaging material.

PubMed

Dasan, Y K; Bhat, A H; Ahmad, Faiz

2017-02-10

The current research discusses the development of poly (lactic acid) (PLA) and poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) reinforced nanocrystalline cellulose bionanocomposites. The nanocrystalline cellulose was derived from waste oil palm empty fruit bunch fiber by acid hydrolysis process. The resulting nanocrystalline cellulose suspension was then surface functionalized by TEMPO-mediated oxidation and solvent exchange process. Furthermore, the PLA/PHBV/nanocrystalline cellulose bionanocomposites were produced by solvent casting method. The effect of the addition of nanocrystalline cellulose on structural, morphology, mechanical and barrier properties of bionanocomposites was investigated. The results revealed that the developed bionanocomposites showed improved mechanical properties and decrease in oxygen permeability rate. Therefore, the developed bio-based composite incorporated with an optimal composition of nanocrystalline cellulose exhibits properties as compared to the polymer blend. Copyright © 2016 Elsevier Ltd. All rights reserved.

Solution-grown small-molecule organic semiconductor with enhanced crystal alignment and areal coverage for organic thin film transistors

DOE PAGES

Bi, Sheng; He, Zhengran; Chen, Jihua; ...

2015-07-24

Drop casting of small-molecule organic semiconductors typically forms crystals with random orientation and poor areal coverage, which leads to significant performance variations of organic thin-film transistors (OTFTs). In this study, we utilize the controlled evaporative self-assembly (CESA) method combined with binary solvent system to control the crystal growth. A small-molecule organic semiconductor,2,5-Di-(2-ethylhexyl)-3,6-bis(5"-n-hexyl-2,2',5',2"]terthiophen-5-yl)-pyrrolo[3,4-c]pyrrole-1,4-dione (SMDPPEH), is used as an example to demonstrate the effectiveness of our approach. By optimizing the double solvent ratios, well-aligned SMDPPEH crystals with significantly improved areal coverage were achieved. As a result, the SMDPPEH based OTFTs exhibit a mobility of 1.6 × 10 -2 cm 2/V s, whichmore » is the highest mobility from SMDPPEH ever reported.« less

Polymeric salt bridges for conducting electric current in microfluidic devices

DOEpatents

Shepodd, Timothy J [Livermore, CA; Tichenor, Mark S [San Diego, CA; Artau, Alexander [Humacao, PR

2009-11-17

A "cast-in-place" monolithic microporous polymer salt bridge for conducting electrical current in microfluidic devices, and methods for manufacture thereof is disclosed. Polymeric salt bridges are formed in place in capillaries or microchannels. Formulations are prepared with monomer, suitable cross-linkers, solvent, and a thermal or radiation responsive initiator. The formulation is placed in a desired location and then suitable radiation such as UV light is used to polymerize the salt bridge within a desired structural location. Embodiments are provided wherein the polymeric salt bridges have sufficient porosity to allow ionic migration without bulk flow of solvents therethrough. The salt bridges form barriers that seal against fluid pressures in excess of 5000 pounds per square inch. The salt bridges can be formulated for carriage of suitable amperage at a desired voltage, and thus microfluidic devices using such salt bridges can be specifically constructed to meet selected analytical requirements.

Multilayer ceramic oxide solid electrolyte for fuel cells and electrolysis cells

NASA Technical Reports Server (NTRS)

Schroeder, James E. (Inventor); Anderson, Harlan U. (Inventor)

1991-01-01

A unitary layered ceramic structure is disclosed which comprises co-sintered layers. The co-sintered structure comprises a sintered central layer of yttria stabilized zirconia (YSZ) which is about 8 mole percent yttria and having a density of at least about 95% of theoretical, and sintered outer layers of strontium lanthanum manganite (LSM) having the approximate molecular composition La.sub.0.8 Sr.sub.0.2 MnO.sub.3, having a density from about 50 to about 60% of theoretical, and having interconnected porosity from about 40 to 50% with an interconnected pore diameter from about one micron to about five microns. The sintered central layer is sandwiched by and bonded and sintered to the outer layers and is essentially free of significant amounts of manganese. A process for making the unitary composition-of-matter is also disclosed which involves tape casting a LSM tape and then on top thereof casting a YSZ tape. The process comprises presintering LSM powder at 1250.degree. F., crushing the presintered commercially available LSM powder, forming a slurry with the crushed LSM, a binder and solvent, tape casting the slurry and allowing the slurry to air dry. A mixture of commercially available submicron size particle YSZ powder is milled with a dispersant and solvent to disperse the YSZ particles thereby forming a dispersed YSZ slurry. The YSZ slurry is then tape cast on the dried LSM tape. If desired, a third layer of LSM can be cast on top of the dried YSZ layer. After drying the composite LSM/YSZ and LSM/YSZ/LSM tapes are fired at 1300.degree. C. No migration of manganese into the YSZ layer was observed with scanning electron microscope/edax in the sintered multilayer tape.

Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

NASA Astrophysics Data System (ADS)

Puthirath, Anand B.; Methattel Raman, Shijeesh; Varma, Sreekanth J.; Jayalekshmi, S.

2016-04-01

Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

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

Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in

2016-04-18

Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra canmore » be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.« less

Morphology Development During Deposition in OPV Low Band Gap Polymer:Bis-Fullerene Heterojunctions: Effect of a Second Solvent

NASA Astrophysics Data System (ADS)

Chen, Huipeng; Hsiao, Yu-Che; Hu, Bin; Dadmun, Mark

2014-03-01

Polymer based bulk-heterojunction solar cells, based on blends of conjugated polymers and fullerenes are one potential option for low cost renewable power generation. One way to improve power conversion efficiency (PCE) of this cell is to increase the open-circuit voltage (Voc) . It has been reported that replacing PCBM with bis-adduct fullerenes (i.e. ICBA) significantly improves Voc and PCE in P3HT device. However, for the most promising low band-gap polymer (LBP) system, replacing PCBM with ICBA gives very poor short-circuit current (Jsc) and PCE although Voc is significantly improved. As Jsc and PCE strongly depend on the morphology, we therefore tried to optimize the morphology of as-cast LBP/ICBA mixture by adding a second solvent with varying solubility to LBP and ICBA to the deposition solution. The results show that there is no change of LBP ordering by adding the second solvent regardless of its solubility. The morphology of all the as-cast samples is then determined by neutron scattering. A homogenous dispersion of ICBA in LBP is found in the sample where the second solvent is selective to LBP, giving poor PCE. Aggregates of ICBA are formed in those samples where the second solvent is selective to ICBA. The resultant morphology improves PCE by up to 246%. A quantitative analysis of neutron data shows that the interfacial area between ICBA aggregates and LBP/ICBA mixed phase is improved in these samples, which appears to facilitate charge transport and reduce the recombination of free charge carriers.

Conversion of Propellant Grade Picrite to Spherical Nitroguanidine, an Insensitive Filler for Melt-Cast TNT Formulations

DTIC Science & Technology

1991-09-01

problem with the solvent/non-solvent process reported by ICT is the inability to recycle the mother liquors. Apparently "strawberries" or " sea urchins ...inevitable for the foreseeable future. Exceptions could include lower production rate items such as sea mines or missile warheads, or speLfic nunitions where...Leitz Orthomat 35 mm automatic camera on polaroid film type 667, Magnification ranged up to X42. 14K 1* Scanning Electron Microscopy ( SEM ) SEM was

A review: fabrication of porous polyurethane scaffolds.

PubMed

Janik, H; Marzec, M

2015-03-01

The aim of tissue engineering is the fabrication of three-dimensional scaffolds that can be used for the reconstruction and regeneration of damaged or deformed tissues and organs. A wide variety of techniques have been developed to create either fibrous or porous scaffolds from polymers, metals, composite materials and ceramics. However, the most promising materials are biodegradable polymers due to their comprehensive mechanical properties, ability to control the rate of degradation and similarities to natural tissue structures. Polyurethanes (PUs) are attractive candidates for scaffold fabrication, since they are biocompatible, and have excellent mechanical properties and mechanical flexibility. PU can be applied to various methods of porous scaffold fabrication, among which are solvent casting/particulate leaching, thermally induced phase separation, gas foaming, emulsion freeze-drying and melt moulding. Scaffold properties obtained by these techniques, including pore size, interconnectivity and total porosity, all depend on the thermal processing parameters, and the porogen agent and solvents used. In this review, various polyurethane systems for scaffolds are discussed, as well as methods of fabrication, including the latest developments, and their advantages and disadvantages. Copyright © 2014. Published by Elsevier B.V.

Optimization and characterization of bioactive glass nanofibers and nanocomposites

NASA Astrophysics Data System (ADS)

Scarber, Reginna E.

Disease affects different areas of the bone and can impact individuals of all pathologies and ethnicities. These bone diseases can result in weakening which leads to trauma during ordinary function, the need for reconstructive surgery, and eventual bone replacement. Tissue engineering can provide a less traumatic and more fundamental solution to the current therapies. Bioactive glasses are promising materials in tissue engineering applications because of their ability to form hydroxycarbonate apatite in the presence of simulated body fluid, support cell adhesion, growth, and differentiation, induce bone formation, and concentrate bone morphogenic proteins in vivo. The research in this dissertation will attempt to improve the quality, yield, and toughness of bioactive glass nanofibrous scaffolds. The three specific aims of this research include, (1) Optimization and Characterization of Surfactant Modified Bioactive Glass (2) Optimization of Direct Synthesis Bioactive glass Nanofibers from Sols (3) Mechanical Properties and In-vitro Biomineralization of Bioglass-loaded Polyglyconate Nanocomposites Created Using the Particulate Leaching Method. The purpose of the first specific aim was to optimize the processing of bioactive glass nanofibers, resulting in greater fiber uniformity with a reduction in beading. The increase in viscosity coupled with the ability of the surfactant to limit polymeric secondary bonding led to improved fiber quality. The focal point of the second specific aim is the production of sol-gel derived glass fibers with high bioactivity prepared by electrospinning without the use of any polymer carrier system. Advantages of this method include decreased processing time, increased production of fibers, and a decrease in the loss of material due to the calcining process. The solvent cast/ particulate leaching method was used to create a nanocomposite of bioglass and the co-polymer polyglyconate (MaxonRTM) for bone tissue scaffolds The biocompatibility of the composite foams was observed and calcium phosphate presence was quantified. The incorporation of bioglass into the polymer matrix improved the strength (modulus - 21.47 MPa) and biocompatibility of the polyglyconate foam. Keywords: Bioactive glass, Electrospinning, Solvent Casting/Particulate Leaching Method, Nanocomposites

Achieving over 9.8% Efficiency in Nonfullerene Polymer Solar Cells by Environmentally Friendly Solvent Processing.

PubMed

Wu, Yue; Zou, Yan; Yang, Hang; Li, Yaowen; Li, Hongkun; Cui, Chaohua; Li, Yongfang

2017-10-25

Nowadays, most of the solution-processed high-efficiency polymer solar cell (PSC) devices are fabricated by halogenated solvents (such as chlorobenzene, 1,2-dichlorobenzene, chloroform, etc.) which are harmful to people and the environment. Therefore, it is essential to develop high-efficiency PSC devices processed by environmentally friendly solvent processing for their industrialization. In this regard, we report a new alkylthio chain-based conjugated polymer PBDB-TS as donor material for environmentally friendly solvent-processed PSCs. PBDB-TS possesses a low-lying HOMO energy level at -5.42 eV and a good solubility in toluene and o-xylene. By using o-xylene and 1% N-methylpyrrolidone as processing solvent, following by the thermal annealing treatment for PBDB-TS:ITIC blend films, well-developed morphological features, and balanced charge transport properties are observed, leading to a high power conversion efficiency (PCE) of 9.85%, higher than that of the device cast from halogenated solvent (PCE = 9.65%). The results suggest that PBDB-TS is an attractive donor material for nonhalogen solvents-processing PSCs.

Antimicrobial activity of TiO2 nanostructures synthesized by hydrothermal method

NASA Astrophysics Data System (ADS)

Surah, Shivani Singh; Sirohi, Siddharth; Nain, Ratyakshi; Kumar, Gulshan

2018-02-01

Titania nanostructures were synthesized by hydrothermal method. Titanium tetrachloride was used as a precursor, sodium hydroxide was used as a solvent. Effect on their morphology by variation of parameters like temperature (110°C, 160°C and 180°C), time (15h,18h, 20h, 22h, 24h) and concentration of the solvent NaOH (5M, 8M, 10 M, 12M) were studied. The obtained TiO2 nanostructures were washed with deionized water. The structure, size, morphology of the prepared nanostructures were analyzed by SEM (scanning electron microscope), DLS (dynamic light scattering), TEM (transmission electron microscope). SEM and TEM revealed the shape, size of the nanostructures. DLS reported the particle size of prepared TiO2 nanoparticles. Polymeric films based on polyvinyl alcohol (PVA) doped with titanium dioxide nanostructures at different weight percentage (0.5, 0.75, 1,2 TiO2/PVA) were prepared using the ultra sonication and solution casting techniques. The appropriate weight of PVA was dissolved in deionized water. The mixture was magnetically stirred continuously and heated (80°C) for 4 hours, until the solution mixture becomes homogenous. Different weight percentage of TiO2 nanostructures were added to deionized water and sonicated for 3 hours to prevent the nanostructures agglomeration. The mixture was mixed with the PVA solution and magnetically stirred for 1 hour to get good dispersion without agglomeration. The final PVA /TiO2 mixture were casted in glass Petridish, were left until dry. Ultrasonication was used as a major factor for preparation in order to get better dispersion. Nanocomposite films were characterized using SEM and were found to exhibit antimicrobial properties when treated with E.coli and pseudomonas.

A high resolution water soluble fullerene molecular resist for electron beam lithography.

PubMed

Chen, X; Palmer, R E; Robinson, A P G

2008-07-09

Traditionally, many lithography resists have used hazardous, environmentally damaging or flammable chemicals as casting solvent and developer. There is now a strong drive towards processes that are safer and more environmentally friendly. We report nanometre-scale patterning of a fullerene molecular resist film with electron beam lithography, using water as casting solvent and developer. Negative tone behaviour is demonstrated after exposure and development. The sensitivity of this resist to 20 keV electrons is 1.5 × 10(-2) C cm(-2). Arrays of lines with a width of 30-35 nm and pitches of 200 and 400 nm, and arrays of dots with a diameter of 40 nm and a pitch of 200 nm have been patterned at 30 keV. The etch durability of this resist was found to be ∼2 times that of a standard novolac based resist. Initial results of the chemical amplification of this material for enhanced sensitivity are also presented.

Drop-casted self-assembling graphene oxide membranes for scanning electron microscopy on wet and dense gaseous samples.

PubMed

Krueger, Mark; Berg, Shannon; Stone, D'Arcy; Strelcov, Evgheni; Dikin, Dmitriy A; Kim, Jaemyung; Cote, Laura J; Huang, Jiaxing; Kolmakov, Andrei

2011-12-27

Graphene oxide sheets dispersed in water and many other solvents can spontaneously assemble into a surface film covering an evaporating droplet due to their amphiphilicity. Thus, graphene oxide membranes with controllable thickness suspended over an orifice have been directly fabricated using a simple drop-cast approach. Mechanical properties and electron transparency tests of these membranes show their use as electron transparent, but molecularly impenetrable, windows for environmental electron microscopy in liquids and dense gaseous media. The foreseeable, broader application of this drop-cast window methodology is the creation of access spots for electron probes to study isolated microsamples in their natural, undisrupted state within the interior of prefabricated devices (such as microfluidic chips or sealed containers of biological, chemically reactive, toxic, or forensic materials).

A novel highly porous ceramic foam with efficient thermal insulation and high temperature resistance properties fabricated by gel-casting process

NASA Astrophysics Data System (ADS)

Yu, Jiahong; Wang, Guixiang; Tang, Di; Qiu, Ya; Sun, Nali; Liu, Wenqiao

2018-01-01

The design of super thermal insulation and high-temperature resistant materials for high temperature furnaces is crucial due to the energy crisis and the huge wasting. Although it is told that numerous studies have been reported about various of thermal insulation materials prepared by different methods, the applications of yttria-stabilized zirconia (YSZ) ceramic foams fabricated through tert-butyl alcohol (TBA)-based gel-casting process in bulk thermal isolators were barely to seen. In this paper, highly porous yttria-stabilized zirconia (YSZ) ceramic foams were fabricated by a novel gel-casting method using tert-butyl alcohol (TBA) as solvent and pore-forming agent. Different raw material ratio, sintering temperature and soaking time were all investigated to achieve optimal thermal insulation and mechanical properties. We can conclude that porosity drops gradually while compressive strength increases significantly with the rising temperature from 1000-1500°C. With prolonged soaking time, there is no obvious change in porosity but compressive strength increases gradually. All specimens have uniformly distributed pores with average size of 0.5-2μm and show good structural stability at high temperature. The final obtained ceramic foams displayed an outstanding ultra-low thermal conductivity property with only 200.6 °C in cold surface while the hot side was 1000 °C (hold 60 min to keep thermal balance before testing) at the thickness of 10 mm.

Stress and structure development in polymeric coatings

NASA Astrophysics Data System (ADS)

Vaessen, Diane Melissa

2002-09-01

The main goal of this research is to measure the stress evolution in various polymer coating systems to establish the mechanisms responsible for stress development, stress relaxation, and defect formation. Investigated systems include ultraviolet (UV)-curable coatings, dense and porous coatings from polymer solutions, and latex coatings. Coating stress was measured using a controlled environment stress apparatus based on a cantilever deflection principle. For acrylate coatings, it was found that by cycling a UV-lamp on and off, keeping the total dose constant, coating stress was lowered by 60% by decreasing the cycle period. A stress minimum was also found to exist for a given dose of radiation. The lower stress is attributed to stress relaxation and/or slower reaction during dark periods. A viscoelastic stress model of this process was formulated and predicted stress values close to those observed experimentally. During drying of cellulose acetate (CA) coatings cast in acetone, final stress increased from 10 to 45 MPa as coating thickness decreased from 60 to 10 mum. This thickness dependent coating stress for a solvent-cast polymer coating is a new finding and is attributed to (1) less shrinkage in thicker coatings due to more trapped solvent (from skinning) and (2) greater amounts of polymer stress relaxation in thicker coatings. For porous CA coatings prepared by dry-cast phase separation, final in-plane stresses ranged from 20 MPa for coatings containing small pores (˜1 mum) to 5 MPa for coatings containing small pores and macrovoids (˜200 mum). For these coatings, a small amount of stress relaxation occurs due to capillary pressure relief. A stress plateau for the macrovoid-containing coating is likely caused by stress-induced rupture of the polymer-rich phase. Measured stress in pigment-free latex coatings was much lower (˜0.3 MPa) than UV-curable and solvent-cast polymer coatings and was found to increase with increasing latex glass transition temperature. Observations from infrared spectroscopy, scanning electron microscopy, camera imaging, and indentation were also studied to correlate coating properties to measured stresses. The results obtained in this thesis will lead to strategies for material selection, process optimization, and defect elimination in polymeric coatings.

Silylene-diethynyl-arylene polymers having liquid crystalline properties

DOEpatents

Barton, Thomas J.; Ding, Yiwei

1993-09-07

The present invention provides linear organosilicon polymers including diethynyl-(substituted)arylene units, and a process for their preparation. These novel polymers possess useful properties including electrical conductivity, liquid crystallinity, and/or photoluminescence. These polymers possess good solubility in organic solvents. A preferred example is produced according to the following reaction scheme. ##STR1## These polymers can be solvent-cast to yield excellent films and can also be pulled into fibers from concentrated solutions. All possess substantial crystallinity as revealed by DSC analysis and observation through a polarizing microscope, and possess liquid crystalline properties.

Flexible energetic materials and related methods

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

Heaps, Ronald J.

Energetic compositions and methods of forming components from the compositions are provided. In one embodiment, a composition includes aluminum, molybdenum trioxide, potassium perchlorate, and a binder. In one embodiment, the binder may include a silicone material. The materials may be mixed with a solvent, such as xylene, de-aired, shaped and cured to provide a self-supporting structure. In one embodiment, one or more reinforcement members may be added to provide additional strength to the structure. For example, a weave or mat of carbon fiber material may be added to the mixture prior to curing. In one embodiment, blade casting techniques maymore » be used to form a structure. In another embodiment, a structure may be formed using 3-dimensional printing techniques.« less

PVA/NaCl/MgO nanocomposites-microstructural analysis by whole pattern fitting method

NASA Astrophysics Data System (ADS)

Prashanth, K. S.; Mahesh, S. S.; Prakash, M. B. Nanda; Somashekar, R.; Nagabhushana, B. M.

2018-04-01

The nanofillers in the macromolecular matrix have displayed noteworthy changes in the structure and reactivity of the polymer nanocomposites. Novel functional materials usually consist of defects and are largely disordered. The intriguing properties of these materials are often attributed to defects. X-ray line profiles from powder diffraction reveal the quantitative information about size distribution and shape of diffracting domains which governs the contribution from small conventional X-ray diffraction (XRD) techniques to enumerate the microstructural information. In this study the MgO nanoparticles were prepared by solution combustion method and PVA/NaCl/MgO nanocomposite films were synthesized by the solvent cast method. Microstructural parameters viz crystal defects like stacking faults and twin faults, compositional inhomogeneity, crystallite size and lattice strain (g in %), were extracted using whole pattern fitting method.

A biocompatible tissue scaffold produced by supercritical fluid processing for cartilage tissue engineering.

PubMed

Kim, Su Hee; Jung, Youngmee; Kim, Soo Hyun

2013-03-01

Supercritical fluids are used in various industrial fields, such as the food and medical industries, because they have beneficial physical and chemical properties and are also nonflammable and inexpensive. In particular, supercritical carbon dioxide (ScCO(2)) is attractive due to its mild critical temperature, pressure values, and nontoxicity. Poly(L-lactide-co-ɛ-caprolactone) (PLCL), which is a biocompatible, biodegradable, and very elastic polymer, has been used in cartilage tissue engineering. However, organic solvents, such as chloroform or dichloromethane, are usually used for the fabrication of a PLCL scaffold through conventional methods. This leads to a cytotoxic effect and long processing time for removing solvents. To alleviate these problems, supercritical fluid processing is introduced here. In this study, we fabricated a mechano-active PLCL scaffold by supercritical fluid processing for cartilage tissue engineering, and we compared it with a scaffold made by a conventional solvent-casting method in terms of physical and biological performance. Also, to examine the optimum condition for preparing scaffolds with ScCO(2), we investigated the effects of pressure, temperature, and the depressurization rate on PLCL foaming. The PLCL scaffolds produced by supercritical fluid processing had a homogeneously interconnected porous structure, and they exhibited a narrow pore size distribution. Also, there was no cytotoxicity of the scaffolds made with ScCO(2) compared to the scaffolds made by the solvent-pressing method. The scaffolds were seeded with chondrocytes, and they were subcutaneously implanted into nude mice for up to 4 weeks. In vivo accumulation of extracellular matrix of cell-scaffold constructs demonstrated that the PLCL scaffold made with ScCO(2) formed a mature and well-developed cartilaginous tissue compared to the PLCL scaffold formed by solvent pressing. Consequently, these results indicated that the PLCL scaffolds made by supercritical fluid processing offer well-interconnected and nontoxic substrates for cell growth, avoiding problems associated with a solvent residue. This suggests that these elastic PLCL scaffolds formed by supercritical fluid processing could be used for cartilage tissue engineering.

The importance of new processing techniques in tissue engineering

NASA Technical Reports Server (NTRS)

Lu, L.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

1996-01-01

The use of polymer scaffolds in tissue engineering is reviewed and processing techniques are examined. The discussion of polymer-scaffold processing explains fiber bonding, solvent casting and particulate leaching, membrane lamination, melt molding, polymer/ceramic fiber composite-foam processing, phase separation, and high-pressure processing.

Structural and optical band gap of PEO/PVP polymer blend

NASA Astrophysics Data System (ADS)

Basappa, M.; Yesappa, L.; Niranjana, M.; Ashokkumar, S. P.; Vandana, M.; Vijeth, H.; Devendrappa, H.

2018-05-01

The PEO/PVP polymers blend film at different wt % of PVP is prepared by solution casting method using methanol as a solvent. The blend was characterized by FT-IR to confirm the blend and the peak observed in the region 1230-980 cm-1 corresponds to C-O-C symmetric and asymmetric stretching. The UV-visible absorption shows red shift from 190 to 220 nm in the ultra violet region is attributed to π→π* transition. The direct and indirect optical band gaps were determined and found decreases from 4.99 to 4.62 eV with increased PVP wt % to 50:50.

Porous inorganic-organic shape memory polymers.

PubMed

Zhang, Dawei; Burkes, William L; Schoener, Cody A; Grunlan, Melissa A

2012-06-21

Thermoresponsive shape memory polymers (SMPs) are a type of stimuli-sensitive materials that switch from a temporary shape back to their permanent shape upon exposure to heat. While the majority of SMPs have been fabricated in the solid form, porous SMP foams exhibit distinct properties and are better suited for certain applications, including some in the biomedical field. Like solid SMPs, SMP foams have been restricted to a limited group of organic polymer systems. In this study, we prepared inorganic-organic SMP foams based on the photochemical cure of a macromer comprised of inorganic polydimethylsiloxane (PDMS) segments and organic poly(ε-caprolactone) (PCL) segments, diacrylated PCL(40)-block-PDMS(37)-block-PCL(40). To achieve tunable pore size with high interconnectivity, the SMP foams were prepared via a refined solvent-casting/particulate-leaching (SCPL) method. By varying design parameters such as degree of salt fusion, macromer concentration in the solvent and salt particle size, the SMP foams with excellent shape memory behavior and tunable pore size, pore morphology, and modulus were obtained.

Control-release of antimicrobial sophorolipid employing different biopolymer matrices

USDA-ARS?s Scientific Manuscript database

Sophorolipid (SL) purified from fermentation broth of Candida bombicola grown on oleic acid and glucose substrates was embedded at 0, 9, 17, and 29% (%-total weight of final product) in solvent-cast films of poly(L-lactic acid) (PLLA), poly(epsilon-caprolactone)(PCL), and poly(hydroxybutyrate)(PHB)....

Leveraging Publically Available Chemical Functional Use Data in Support of Exposure Prediction

EPA Science Inventory

The U.S. EPA Exposure Forecasting (ExpoCast) project aims to provide rapid screening-level exposure predictions for thousands of chemicals, most of which lack detailed exposure data. Chemical functional use - the role a chemical plays in processes or products (e.g. solvent, ant...

Distinguishing the importance of fullerene phase separation from polymer ordering in the performance of low band gap polymer: Bis-fullerene heterojunctions

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

Chen, Huipeng; Hsiao, Yu -Che; Chen, Jihua

2014-09-16

It is known, one way to improve power conversion efficiency (PCE) of polymer based bulk-heterojunction (BHJ) photovoltaic cells is to increase the open circuit voltage (V oc). Replacing PCBM with bis-adduct fullerenes significantly improves V oc and the PCE in devices based on the conjugated polymer poly(3-hexyl thiophene) (P3HT). However, for the most promising low band-gap polymer (LBP) system, replacing PCBM with ICBA results in poor short-circuit current (J sc) and PCE although V oc is significantly improved. The optimization of the morphology of as-cast LBP/bis-fullerene BHJ photovoltaics is attempted by adding a co-solvent to the polymer/fullerene solution prior tomore » film deposition. Varying the solubility of polymer and fullerene in the co-solvent, bulk heterojunctions are fabricated with no change of polymer ordering, but with changes in fullerene phase separation. The morphologies of the as-cast samples are characterized by small angle neutron scattering and neutron reflectometry. A homogenous dispersion of ICBA in LBP is found in the samples where the co-solvent is selective to the polymer, giving poor device performance. Aggregates of ICBA are formed in samples where the co-solvent is selective to ICBA. Furthermore, the resultant morphology improves PCE by up to 246%. Finally, a quantitative analysis of the neutron data shows that the interfacial area between ICBA aggregates and its surrounding matrix is improved, facilitating charge transport and improving the PCE.« less

Fabrication and characterization of anode-supported micro-tubular solide oxide fuel cell by phase inversion method

NASA Astrophysics Data System (ADS)

Ren, Cong

Nowadays, the micro-tubular solid oxide fuel cells (MT-SOFCs), especially the anode supported MT-SOFCs have been extensively developed to be applied for SOFC stacks designation, which can be potentially used for portable power sources and vehicle power supply. To prepare MT-SOFCs with high electrochemical performance, one of the main strategies is to optimize the microstructure of the anode support. Recently, a novel phase inversion method has been applied to prepare the anode support with a unique asymmetrical microstructure, which can improve the electrochemical performance of the MT-SOFCs. Since several process parameters of the phase inversion method can influence the pore formation mechanism and final microstructure, it is essential and necessary to systematically investigate the relationship between phase inversion process parameters and final microstructure of the anode supports. The objective of this study is aiming at correlating the process parameters and microstructure and further preparing MT-SOFCs with enhanced electrochemical performance. Non-solvent, which is used to trigger the phase separation process, can significantly influence the microstructure of the anode support fabricated by phase inversion method. To investigate the mechanism of non-solvent affecting the microstructure, water and ethanol/water mixture were selected for the NiO-YSZ anode supports fabrication. The presence of ethanol in non-solvent can inhibit the growth of the finger-like pores in the tubes. With the increasing of the ethanol concentration in the non-solvent, a relatively dense layer can be observed both in the outside and inside of the tubes. The mechanism of pores growth and morphology obtained by using non-solvent with high concentration ethanol was explained based on the inter-diffusivity between solvent and non-solvent. Solvent and non-solvent pair with larger Dm value is benefit for the growth of finger-like pores. Three cells with different anode geometries was prepared, La0.85Sr0.15MnO 3 (LSM) was selected as the cathode. Cells were tested at 800°C using humidified H2 as fuel. Cell with anode prepared by using pure water as non-solvent shows a maximum power density up to 437mW/cm 2. By comparing the anode geometry and electrochemical performance, it indicated that microstructure with longer finger-like pores and thinner macrovoid free layer close to the inner side of the tube is benefit to cell performance. Another factor that can affect the microstructure of anode support is the ratio of solvent and polymer binder. In this research, anode-supported MT-SOFCs have been fabricated by phase inversion method. The effect of the viscosity of the casting slurry on the microstructure of YSZ-NiO anode support has been investigated. The microstructure of the YSZ-NiO support can be effectively controlled by varying the slurry composition with different solvent and polymer binder content. Gas permeation and mechanical strength of the YSZ-NiO support have been measured and four YSZ-NiO anode supports have been chosen for subsequent cell fabrication. The effective conductivity of the different anode supports has been measured at room temperature after reduced. Anode-supported single cells with YSZ electrolyte and LSM/YSZ cathode are fabricated and tested. Maximum cell power densities of 606 mWcm-2, 449 mWcm -2, 339 mWcm-2 and 253 mWcm-2 have been obtained respectively at 750 °C with humidified hydrogen as fuel and ambient air as oxidant. The correlation between the cell electrochemical performance and anode microstructures has been discussed. Adjusting the slurry composition by introducing additive is also an effective approach to tailor the microstructure of the anode support. Poly(ethylene glycol) (PEG), which is a common applied polymer additive, was selected to fabricate the YSZ-NiO anode supports. The effect of molecular weight and amount of PEG additive on the thermodynamics of the casting solutions was characterized by measuring the coagulation value. Viscosity of the casting slurries was also measured and the influence of PEG additive on viscosity was studied and discussed. The presence of PEG in the casting slurry can greatly influence the final anode support microstructure. Based on the microstructure result and the measured gas permeation value, two anode supports were selected for cell fabrication. For cell with the anode support fabricated using slurry with PEG additive, a maximum cell power density of 704 mWcm-2 is obtained at 750 oC with humidified hydrogen as fuel and ambient air as oxidant; cell fabricated without any PEG additive shows the peak cell power density of 331 mWcm-2. The relationship between anode microstructure and cell performance was discussed. Anode-supported micro-tubular solid oxide fuel cells (MT-SOFCs) based on BaZr0.1Ce0.7Y0.1Yb0.1O 3-delta (BZCYYb) proton-conducting electrolyte have been prepared using a phase inversion method. Three sulfur-free polymer binder candidates ethyl cellulose (EC), polyvinylidene fluoride (PVDF), polyetherimide (PEI) and sulfur-containing polythersulfone (PESf) were used as polymer binders to fabricate NiO-BZCYYb anode. The overall influence of polymer binder on the anode supports was evaluated. Sulfide impurity generated from PESf was revealed by XRD and X-ray photoelectron spectroscopy (XPS). The difference in the anode microstructure for samples fabricated by different polymer binders was examined by scanning electron microscope (SEM) and analyzed by measuring the gas permeation data of the reduced samples. Single cells based on different anode supports were characterized in anode-supported MT-SOFCs with the cell configuration of Ni-BZCYYb anode, BZCYYb electrolyte and La0.6Sr 0.4Co0.2Fe0.8O3-delta (LSCF)-BZCYYb cathode at 650 °C using hydrogen as fuel and ambient air as oxidant. MT-SOFCs of the anode fabricated using PEI show maximum power density of 0.45 Wcm -2 compared with 0.35 Wcm-2 for cells fabricated with PESf. The difference in cell performance was attributed to the phase purity of the anode fabricated by different polymer binders. Sulfur-free polymer binder PEI exhibits advantages over the commonly applied PESf and other sulfur-free polymer binder candidates. To eliminate the skin layer formed close to the inner side of the tubular sample when using the phase inversion method. Polyethersulfone (PESf)-polyethylenimine (PEI) blend was employed as the polymer binder to fabricate the micro-tubular solid oxide fuel cells (MT-SOFCs). The potential impurity introduced in the anode support by the polymer binder was examined by XPS and the resulting novel microstructure was analyzed based on the backscattered electron (BSE) images. Cells fabricated with blend polymer binder showed significantly enhanced power output compared with those cells only fabricated with PEI or PESf. The improved cell performance demonstrated that using blend polymer as binder is a promising and versatile approach for MT-SOFC fabrication via phase inversion method. Finally, to investigate the effect of the anode microstructure on the total cell performance, two types of anode support with different microstructure were prepared via the phase inversion method at different temperature. Cells fabricated based on these two anode supports were tested at 750 °C with hydrogen or hydrogen mixture with fuel gas. The measured current density-voltage (I-V) curves were fitted by a polarization model, and several parameters were archived through the modeling process. The influence of the anode support on the total cell performance was discussed based on the calculated result.

Birefringence control of solution-cast film of cellulose triacetate

NASA Astrophysics Data System (ADS)

Kiyama, Ayumi; Nobukawa, Shogo; Yamaguchi, Masayuki

2017-10-01

We controlled the optical anisotropy of a solution-cast film composed of cellulose triacetate (CTA) by adding ferrocene. Owing to the molecular orientation in the film plane of solution-cast films, which results from the normal stress applied during the solvent evaporation process, the average refractive index is usually higher in the plane of the film than in the thickness direction. We found that the addition of ferrocene, which is miscible with CTA, reduced the optical anisotropy by nematic interaction; i.e., ferrocene molecules are forcibly embedded into the film plane accompanying the CTA chains. Because the direction of anisotropic polarizability of ferrocene is perpendicular to the long axis of the molecule, the refractive index in the thickness direction is reduced. Furthermore, the stress-optical coefficient in the glassy state is reduced by the addition of ferrocene.

Self-Assembled Infrapatellar Fat-Pad Progenitor Cells on a Poly-ε-Caprolactone Film For Cartilage Regeneration.

PubMed

Prabhakar, Alisha; Lynch, Amy P; Ahearne, Mark

2016-04-01

Cartilage defects resulting from osteoarthritis (OA) or physical injury can severely reduce the quality of life for sufferers. Current treatment options are costly and not always effective in producing stable hyaline cartilage. Here we investigated a new treatment option that could potentially repair and regenerate damaged cartilage tissue. This novel approach involves the application of infrapatellar fat-pad derived chondroprogenitor cells onto a mechanically stable biodegradable polymer film that can be easily implanted into a defect site. Poly-ε-caprolactone (PCL) films were fabricated via solvent casting in either acetone or chloroform. The hydrophobicity, mechanical properties, and surface morphology of the films were examined. Progenitor cells from infrapatellar fat-pad were isolated, expanded, and then seeded onto the films. The cells were allowed to self-assemble on films, and these were then cultured in a chemically defined chondrogenic media for 28 days. The self-assembled tissue was characterized via histological staining, gene expression analysis, immunohistochemistry, and biochemical analysis. Chondrogenic differentiation was induced to generate a cartilaginous matrix upon the films. Despite differences between in the appearance, surface morphology, and mechanical properties of the films cast in chloroform or acetone, both methods produced tissues rich in sulfated glycosaminoglycan and collagen, although the extracellular matrix produced on chloroform-cast films appeared to contain more collagen type II and less collagen type I than acetone-cast films. These self-assembled constructs have the potential to be implanted into defect sites as a potential treatment for cartilage defect regeneration. Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Orodispersible films in individualized pharmacotherapy: The development of a formulation for pharmacy preparations.

PubMed

Visser, J Carolina; Woerdenbag, Herman J; Crediet, Stefan; Gerrits, Edwin; Lesschen, Marjan A; Hinrichs, Wouter L J; Breitkreutz, Jörg; Frijlink, Henderik W

2015-01-15

Orodispersible films (ODFs) are promising drug delivery systems for customized small scale pharmacy preparations. The aim of the present study was to develop a versatile casting solution suitable for the extemporaneous production of ODFs to which active pharmaceutical ingredients (APIs) can be added. Different combinations of film forming agents and other excipients and different casting heights were tested for their suitability for production of ODFs. The best suitable casting solution contained hypromellose, carbomer, glycerol, disodium EDTA and trometamol. This casting solution was used to prepare ODFs containing water-soluble APIs (enalapril maleate and prednisolone disodium phosphate) and a poorly water-soluble API (diazepam) for which ethanol 96% was used as co-solvent.The water-soluble APIs as well as ethanol influenced the viscosity of the casting solution, mechanical properties and disintegration time of the ODFs. All ODFs containing API met the requirements on uniformity of mass and uniformity of content set by the European Pharmacopoeia (2014) (Ph. Eur.) 8th edition. In conclusion, ODFs of good pharmaceutical quality can be prepared on small scale. Hereby opening the perspective of using ODFs for individualized pharmacotherapy. Copyright © 2014 Elsevier B.V. All rights reserved.

Water as foaming agent for open cell polyurethane structures.

PubMed

Haugen, H; Ried, V; Brunner, M; Will, J; Wintermantel, E

2004-04-01

The problem of moisture in polymer processing is known to any polymer engineer, as air bubbles may be formed. Hence granulates are generally dried prior to manufacturing. This study tried to develop a novel processing methods for scaffolds with controlled moisture content in thermoplastic polyurethane. The common foaming agents for polyurethane are organic solvents, whose residues remaining in the scaffold may be harmful to adherent cells, protein growth factors or nearby tissues. Water was used as a foaming agent and NaCl was used as porogens to achieve an open-cell structure. The polyether-polyurethane samples were processed in a heated press, and achieved a porosity of 64%. The pore size ranged between 50 and 500 microm. Human fibroblasts adhered and proliferate in the scaffold. A non-toxic production process was developed to manufacture a porous structure with a thermoplastic polyether-polyurethane. The process enables a mass-production of samples with adjustable pore size and porosity. In contrast to an existing method (solvent casting), the processing of the samples was not limited by its thickness. The process parameters, which attribute mostly to the pore building, were filling volume, temperature, NaCl-concentration and water-uptake rate.

Dual drug-loaded nanoparticles on self-integrated scaffold for controlled delivery

PubMed Central

Bennet, Devasier; Marimuthu, Mohana; Kim, Sanghyo; An, Jeongho

2012-01-01

Antioxidant (quercetin) and hypoglycemic (voglibose) drug-loaded poly-D,L-lactideco-glycolide nanoparticles were successfully synthesized using the solvent evaporation method. The dual drug-loaded nanoparticles were incorporated into a scaffold film using a solvent casting method, creating a controlled transdermal drug-delivery system. Key features of the film formulation were achieved utilizing several ratios of excipients, including polyvinyl alcohol, polyethylene glycol, hyaluronic acid, xylitol, and alginate. The scaffold film showed superior encapsulation capability and swelling properties, with various potential applications, eg, the treatment of diabetes-associated complications. Structural and light scattering characterization confirmed a spherical shape and a mean particle size distribution of 41.3 nm for nanoparticles in the scaffold film. Spectroscopy revealed a stable polymer structure before and after encapsulation. The thermoresponsive swelling properties of the film were evaluated according to temperature and pH. Scaffold films incorporating dual drug-loaded nanoparticles showed remarkably high thermoresponsivity, cell compatibility, and ex vivo drug-release behavior. In addition, the hybrid film formulation showed enhanced cell adhesion and proliferation. These dual drug-loaded nanoparticles incorporated into a scaffold film may be promising for development into a transdermal drug-delivery system. PMID:22888222

Anionic membrane and ionomer based on poly(2,6-dimethyl-1,4-phenylene oxide) for alkaline membrane fuel cells

NASA Astrophysics Data System (ADS)

Ong, Ai Lien; Saad, Saeed; Lan, Rong; Goodfellow, Robert J.; Tao, Shanwen

2011-10-01

Hydroxyl-ion conductive poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) membranes with different characteristics were prepared via relatively simple bromination/amination serial reactions with reduced number of involved chemicals and shorter reaction time. The effects of reactants ratio, reaction atmosphere, polymer concentration, casting solvent, and hydroxylation treatment on reaction were investigated in details. The microstructure, water uptake, swelling ratio, ion-exchange capacity and ionic conductivity of the membranes were also studied. The obtained results demonstrate that, the ionic conductivity of the membrane is dependent on casting solvent. The N-methyl-2-pyrrolidonecast membrane exhibits the highest conductivity with the thinnest film. Although the membrane was prepared via a relatively simple preparation route with least toxic chemicals, a competitive ionic conductivity value of 1.64 × 10-2 S cm-1 was achieved at 60 °C. A power density of 19.5 mW cm-2 has been demonstrated from the alkaline membrane fuel cell operated at 70 °C, assembled from the entirely homemade membrane electrode assembly without any hot-pressing.

HA/nylon 6,6 porous scaffolds fabricated by salt-leaching/solvent casting technique: effect of nano-sized filler content on scaffold properties

PubMed Central

Mehrabanian, Mehran; Nasr-Esfahani, Mojtaba

2011-01-01

Nanohydroxyapatite (n-HA)/nylon 6,6 composite scaffolds were produced by means of the salt-leaching/solvent casting technique. NaCl with a distinct range size was used with the aim of optimizing the pore network. Composite powders with different n-HA contents (40%, 60%) for scaffold fabrication were synthesized and tested. The composite scaffolds thus obtained were characterized for their microstructure, mechanical stability and strength, and bioactivity. The microstructure of the composite scaffolds possessed a well-developed interconnected porosity with approximate optimal pore size ranging from 200 to 500 μm, ideal for bone regeneration and vascularization. The mechanical properties of the composite scaffolds were evaluated by compressive strength and modulus tests, and the results confirmed their similarity to cortical bone. To characterize bioactivity, the composite scaffolds were immersed in simulated body fluid for different lengths of time and results monitored by scanning electron microscopy and energy dispersive X-ray microanalysis to determine formation of an apatite layer on the scaffold surface. PMID:21904455

Single molecule studies of solvent-dependent diffusion and entrapment in poly(dimethylsiloxane) thin films.

PubMed

Lange, Jeffrey J; Culbertson, Christopher T; Higgins, Daniel A

2008-12-15

Single molecule microscopic and spectroscopic methods are employed to probe the mobility and physical entrapment of dye molecules in dry and solvent-loaded poly(dimethylsiloxane) (PDMS) films. PDMS films of approximately 220 nm thickness are prepared by spin casting dilute solutions of Sylgard 184 onto glass coverslips, followed by low temperature curing. A perylene diimide dye (BPPDI) is used to probe diffusion and molecule-matrix interactions. Two classes of dye-loaded samples are investigated: (i) those incorporating dye dispersed throughout the films ("in film" samples) and (ii) those in which the dye is restricted primarily to the PDMS surface ("on film" samples). Experiments are performed under dry nitrogen and at various levels of isopropyl alcohol (IPA) loading from the vapor phase. A PDMS-coated quartz-crystal microbalance is employed to monitor solvent loading and drying of the PDMS and to ensure equilibrium conditions are achieved. Single molecules are shown to be predominantly immobile under dry conditions and mostly mobile under IPA-saturated conditions. Quantitative methods for counting the fluorescent spots produced by immobile single molecules in optical images of the samples demonstrate that the population of mobile molecules increases nonlinearly with IPA loading. Even under IPA saturated conditions, the population of fixed molecules is found to be greater than zero and is greatest for "in film" samples. Fluorescence correlation spectroscopy is used to measure the apparent diffusion coefficient for the mobile molecules, yielding a mean value of D = 1.4(+/-0.4) x 10(-8) cm(2)/s that is virtually independent of IPA loading and sample class. It is concluded that a nonzero population of dye molecules is physically entrapped within the PDMS matrix under all conditions. The increase in the population of mobile molecules under high IPA conditions is attributed to the filling of film micropores with solvent, rather than by incorporation of molecularly dispersed solvent into the PDMS.

High throughput research and evaporation rate modeling for solvent screening for ethylcellulose barrier membranes in pharmaceutical applications.

PubMed

Schoener, Cody A; Curtis-Fisk, Jaime L; Rogers, True L; Tate, Michael P

2016-10-01

Ethylcellulose is commonly dissolved in a solvent or formed into an aqueous dispersion and sprayed onto various dosage forms to form a barrier membrane to provide controlled release in pharmaceutical formulations. Due to the variety of solvents utilized in the pharmaceutical industry and the importance solvent can play on film formation and film strength it is critical to understand how solvent can influence these parameters. To systematically study a variety of solvent blends and how these solvent blends influence ethylcellulose film formation, physical and mechanical film properties and solution properties such as clarity and viscosity. Using high throughput capabilities and evaporation rate modeling, thirty-one different solvent blends composed of ethanol, isopropanol, acetone, methanol, and/or water were formulated, analyzed for viscosity and clarity, and narrowed down to four solvent blends. Brookfield viscosity, film casting, mechanical film testing and water permeation were also completed. High throughput analysis identified isopropanol/water, ethanol, ethanol/water and methanol/acetone/water as solvent blends with unique clarity and viscosity values. Evaporation rate modeling further rank ordered these candidates from excellent to poor interaction with ethylcellulose. Isopropanol/water was identified as the most suitable solvent blend for ethylcellulose due to azeotrope formation during evaporation, which resulted in a solvent-rich phase allowing the ethylcellulose polymer chains to remain maximally extended during film formation. Consequently, the highest clarity and most ductile films were formed. Employing high throughput capabilities paired with evaporation rate modeling allowed strong predictions between solvent interaction with ethylcellulose and mechanical film properties.

Novel multiphase systems based on thermoplastic chitosan: Analysis of the structure-properties relationships

NASA Astrophysics Data System (ADS)

Avérous, Luc; Pollet, Eric

2016-03-01

In the last years, biopolymers have attracted great attention. It is for instance the case of chitosan, a linear polysaccharide. It is a deacetylated derivative of chitin, which is the second most abundant polysaccharide found in nature after cellulose. Chitosan has been found to be nontoxic, biodegradable, biofunctional, and biocompatible in addition to having antimicrobial and antifungal properties, and thus has a great potential for environmental (packaging,) or biomedical applications.For preparing chitosan-based materials, only solution casting or similar methods have been used in all the past studies. Solution casting have the disadvantage in low efficiency and difficulty in scaling-up towards industrial applications. Besides, a great amount of environmentally unfriendly chemical solvents are used and released to the environment in this method. The reason for not using a melt processing method like extrusion or kneading in the past studies is that chitosan, like many other polysaccharides such as starch, has very low thermal stability and degrade prior to melting. Therefore, even if the melt processing method is more convenient and highly preferred for industrial production, its adaptation for polysaccharide-based materials remains very difficult. However, our recently published studies has demonstrated the successful use of an innovative melt processing method (internal mixer, extrusion,) as an alternative route to solution casting, for preparing materials based on thermoplastic chitosan. These promising thermoplastic materials, obtained by melt processing, have been the main topic of recent international projects, with partners from different countries Multiphase systems based on various renewable plasticizers have been elaborated and studied. Besides, different blends, and nano-biocomposites based on nanoclays, have been elaborated and fully analyzed. The initial consortium of this vast project was based on an international consortium (Canada, Australia, France). This project is currently ongoing and open, with new international academic partners (Mexico, Brazil and Spain).

Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes

PubMed Central

Liu, Jie; Lu, Xiaolong; Wu, Chunrui

2013-01-01

Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

Preparation and characterization of free films of high amylose/pectin mixtures cross-linked with sodium trimetaphosphate.

PubMed

Prezotti, Fabíola Garavello; Meneguin, Andréia Bagliotti; Evangelista, Raul Cesar; Cury, Beatriz Stringhetti Ferreira

2012-11-01

High amylose and pectin were mixed at 1:1 mass ratio and cross-linked with sodium trimetaphosphate (STMP) in alkaline medium. Films were prepared from aqueous dispersions of these cross-linked polymer blend at three different concentrations (3, 4 and 5%), by solvent casting method. Characterization of the films included thickness, surface morphology, water uptake, water vapor permeability (WVP), tensile strength measurements and enzymatic digestion. The cross-linking allowed to obtain films with improved mechanical properties and reduced WVP. The high resistance to enzymatic digestion exhibited by these films represents a promising approach to their application in the development of colon drug delivery systems.

Application of cow milk-derived carbon dots/Ag NPs composite as the antibacterial agent

NASA Astrophysics Data System (ADS)

Han, Shuai; Zhang, He; Xie, Yujie; Liu, Liangliang; Shan, Changfu; Li, Xiangkai; Liu, Weisheng; Tang, Yu

2015-02-01

Cow milk-derived carbon dots (CMCDs) were prepared by hydrothermal treatment of cow milk, and the as-prepared CMCDs were further extracted by ethyl acetate to obtain amphiphilic CMCDs (ACMCDs). Using the ACMCDs both as a reducing agent and a template, the ACMCDs-supported silver nanoparticles (ACMCD-Ag nanocomposites) were prepared, which showed good biocidal effect on both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterias. After that, a novel ACMCD-Ag/polymethylmethacrylate nanocomposite antibacterial film was fabricated by solvent casting method. Due to the excellent antibacterial, light admitting, and flexible properties, the nanocomposite antibacterial film is considered to be of great potential in applications.

Uniaxial alignment of triisopropylsilylethynyl pentacene via zone-casting technique.

PubMed

Su, Yajun; Gao, Xiang; Liu, Jiangang; Xing, Rubo; Han, Yanchun

2013-09-14

Uniaxially aligned triisopropylsilylethynyl pentacene (TIPS-pentacene) crystals over a large area were fabricated using zone-casting technique. The array of TIPS-pentacene displayed a high orientation degree with a dichroic ratio (DR) of 0.80. The crystals were arranged with c axis perpendicular to the substrate and the long axis of the ribbon corresponded to the a axis of TIPS-pentacene. The properties of the solutions and the processing parameters were shown to influence the formation of the oriented TIPS-pentacene crystalline array. Solvent with a low boiling point (such as chloroform) favoured the orientation of the ribbon-like crystals. The concentration of the solution should be appropriate, ensuring the crystallization velocity of TIPS-pentacene matching with the receding of the meniscus. Besides, we proved that the casting speed should be large enough to induce a sufficient concentration gradient. The orientation mechanism of TIPS-pentacene was attributed to a synergy of the ordered nuclei and a match between the crystallization velocity and the casting speed. Field effect transistors (FETs) based on the oriented TIPS-pentacene crystalline array showed a mobility of 0.67 cm(2) V(-1) s(-1).

Barium titanate tape properties for MLCC application using different binder systems

NASA Astrophysics Data System (ADS)

Yoon, Dang-Hyok

Most of multilayer ceramic capacitor (MLCC) industries are currently using solvent-based slip systems, although water-based slips have been receiving increasing attention due to reduced health and environmental hazards. The current work focuses on two main fields to meet the challenges in MLCC processing in aqueous media. One is the comparison between water- and solvent-based slip systems using design of experiments (DOE). The other is the understanding of Ba2+ ion leaching behavior in water and its effect on tape properties. For the first part, twenty four kinds of BaTiO3 slips were investigated using three different binder systems: one solvent-based, and two water-based systems. Tape casting, sintering and characterization were conducted. Slip viscosity and tape strength of the green tape depended significantly on the binder type. It was possible to achieve a higher green density for water-based system than that for a solvent-based one. Most of the green body properties from solvent-based system depended on the ceramic powder. On the other hand, the dispersant was the most significant factor for the green body properties of two water-based systems. Sintered properties such as microstructure and dielectric permittivity for three systems depended significantly on the type of ceramic powder. An optimization was performed for each system by means of a scorecard. By choosing the optimum condition, comparable results were drawn for the water-based system compared to a solvent-based one for MLCC application. For the second part, the amount of Ba2+ ion leaching from BaTiO3 in water was determined by an EDTA titration method. The greater extent and the faster rate of Ba2+ leaching were found at the lower solution pH. The excess free barium ions expressed by means of the Ba/Ti ratio adversely affected most tape properties. To passivate BaTiO 3 surface from Ba2+ ion leaching in water, passivation agent layer (PAL) was formed by drying the slurry after adding a commercial polymeric dispersant. Compared to the conventional dispersant adding method, this PAL method was more effective in reducing the amount of Ba2+ leaching. Moreover, using PAL did not deteriorate any of green and sintered properties of BaTiO3 tape.

Defect-free ultrahigh flux asymmetric membranes

DOEpatents

Pinnau, Ingo; Koros, William J.

1990-01-01

Defect-free, ultrahigh flux integrally-skinned asymmetric membranes having extremely thin surface layers (<0.2 .mu.m) comprised of glassy polymers are disclosed. The membranes are formed by casting an appropriate drope followed by forced convective evaporation of solvent to obtain a dry phase separated asymmetrical structure. The structure is then washed in a precipitation liquid and dried.

High surface area nanocrystalline hausmannite synthesized by a solvent-free route

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

Herrera-Miranda, Daniel; Ponrouch, Alexandre; Pons, Josefina

Highlights: ► High surface area Mn{sub 3}O{sub 4} nanoparticles obtained by a solvent-free low temperature route. ► 3,6,9-Trioxadecanoic acid allows to obtain nanocrystalline hausmannite. ► Tape casted electrodes show up to 300 mAh g{sup −1} capacity after more than 40 cycles at a C/3 rate. ► Upper cut off voltage strongly influences capacity retention upon cycling at high C rates. -- Abstract: Nanocrystalline high surface area Mn{sub 3}O{sub 4} powder was obtained at low temperature by a solvent-free route. The precursor was a mixture of manganese (II) acetate, 3,6,9-trioxadecanoic acid (TODA) and ammonium acetate that were intimately mixed by groundingmore » in an agate mortar. Nanocrystalline Mn{sub 3}O{sub 4} was obtained by thermal treatment at 120 °C. Powder X-ray diffraction, selected area electron diffraction, high resolution transmission electron microscopy, and Fourier transformed infrared characterization confirmed the formation of the hausmannite phase. The as-prepared mesoporous material has high specific surface area (120 m{sup 2} g{sup −1}). The performances of tape casted Mn{sub 3}O{sub 4} nanopowder electrodes were investigated as anode material for lithium ion batteries. High capacity values were achieved at diverse C rates. Capacity fading was found to be dependent on the upper cut off voltage, the presence of a plateau at 2.25 V vs. Li{sup +}/Li being detrimental for long term cyclability.« less

Method for producing a selectively permeable separation module

DOEpatents

Stone, Mark L.; Orme, Christopher J.; Peterson, Eric S.

2000-03-14

A method and apparatus is provided for casting a polymeric membrane on the inside surface of porous tubes to provide a permeate filter system capable of withstanding hostile operating conditions and having excellent selectivity capabilities. Any polymer in solution, by either solvent means or melt processing means, is capable of being used in the present invention to form a thin polymer membrane having uniform thickness on the inside surface of a porous tube. Multiple tubes configured as a tubular module can also be coated with the polymer solution. By positioning the longitudinal axis of the tubes in a substantially horizontal position and rotating the tube about the longitudinal axis, the polymer solution coats the inside surface of the porous tubes without substantially infiltrating the pores of the porous tubes, thereby providing a permeate filter system having enhanced separation capabilities.

Silk-based biomaterials functionalized with fibronectin type II promotes cell adhesion.

PubMed

Pereira, Ana Margarida; Machado, Raul; da Costa, André; Ribeiro, Artur; Collins, Tony; Gomes, Andreia C; Leonor, Isabel B; Kaplan, David L; Reis, Rui L; Casal, Margarida

2017-01-01

The objective of this work was to exploit the fibronectin type II (FNII) module from human matrix metalloproteinase-2 as a functional domain for the development of silk-based biopolymer blends that display enhanced cell adhesion properties. The DNA sequence of spider dragline silk protein (6mer) was genetically fused with the FNII coding sequence and expressed in Escherichia coli. The chimeric protein 6mer+FNII was purified by non-chromatographic methods. Films prepared from 6mer+FNII by solvent casting promoted only limited cell adhesion of human skin fibroblasts. However, the performance of the material in terms of cell adhesion was significantly improved when 6mer+FNII was combined with a silk-elastin-like protein in a concentration-dependent behavior. With this work we describe a novel class of biopolymer that promote cell adhesion and potentially useful as biomaterials for tissue engineering and regenerative medicine. This work reports the development of biocompatible silk-based composites with enhanced cell adhesion properties suitable for biomedical applications in regenerative medicine. The biocomposites were produced by combining a genetically engineered silk-elastin-like protein with a genetically engineered spider-silk-based polypeptide carrying the three domains of the fibronectin type II module from human metalloproteinase-2. These composites were processed into free-standing films by solvent casting and characterized for their biological behavior. To our knowledge this is the first report of the exploitation of all three FNII domains as a functional domain for the development of bioinspired materials with improved biological performance. The present study highlights the potential of using genetically engineered protein-based composites as a platform for the development of new bioinspired biomaterials. Copyright © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Effect of osteoblastic culture conditions on the structure of poly(DL-lactic-co-glycolic acid) foam scaffolds

NASA Technical Reports Server (NTRS)

Goldstein, A. S.; Zhu, G.; Morris, G. E.; Meszlenyi, R. K.; Mikos, A. G.; McIntire, L. V. (Principal Investigator)

1999-01-01

Poly(DL-lactic-co-glycolic acid) (PLGA) foams are an osteoconductive support that holds promise for the development of bone tissue in vitro and implantation into orthopedic defects. Because it is desirable that foams maintain their shape and size, we examined a variety of foams cultured in vitro with osteoblastic cells. Foams were prepared with different porosities and pore sizes by the method of solvent casting/porogen leaching using 80, 85, and 90 wt% NaCl sieved with particle sizes of 150-300 and 300-500 microm and characterized by mercury intrusion porosimetry. Foams seeded with cells were found to have volumes after 7 days in static culture that decreased with increasing porosity: the least porous exhibited no change in volume while the most porous foams decreased by 39 +/- 10%. In addition, a correlation was observed between decreasing foam volume after 7 days in culture and decreasing internal surface area of the foams prior to seeding. Furthermore, foams prepared with the 300-500 microm porogen had lower porosities, greater mean wall thicknesses between adjacent pores, and larger volumes after 7 days in culture than those prepared with the smaller porogen. Two culture conditions for maintaining cells, static and agitated (in a rotary vessel), were found to have similar influences on foam size, cell density, and osteoblastic function for 7 and 14 days in culture. Finally, we examined unseeded foams in aqueous solutions of pH 3.0, 5.0, and 7.4 and found no significant decrease in foam size with degradation. This study demonstrates that adherent osteoblastic cells may collapse very porous PLGA foams prepared by solvent casting/particulate leaching: a potentially undesirable property for repair of orthopedic defects.

Polymeric electrolytes based on hydrosilyation reactions

DOEpatents

Kerr, John Borland [Oakland, CA; Wang, Shanger [Fairfield, CA; Hou, Jun [Painted Post, NY; Sloop, Steven Edward [Berkeley, CA; Han, Yong Bong [Berkeley, CA; Liu, Gao [Oakland, CA

2006-09-05

New polymer electrolytes were prepared by in situ cross-linking of allyl functional polymers based on hydrosilation reaction using a multifunctional silane cross-linker and an organoplatinum catalyst. The new cross-linked electrolytes are insoluble in organic solvent and show much better mechanical strength. In addition, the processability of the polymer electrolyte is maintained since the casting is finished well before the gel formation.

A comparison between the dimensions of positive transtibial residual limb molds prepared by air pressure casting and weight-bearing casting methods.

PubMed

Hajiaghaei, Behnam; Ebrahimi, Ismail; Kamyab, Mojtaba; Saeedi, Hassan; Jalali, Maryam

2016-01-01

Creating a socket with proper fit is an important factor to ensure the comfort and control of prosthetic devices. Several techniques are commonly used to cast transtibial stumps but their effect on stump shape deformation is not well understood. This study compares the dimensions, circumferences and volumes of the positive casts and also the socket comfort between two casting methods. Our hypothesis was that the casts prepared by air pressure method have less volume and are more comfortable than those prepared by weight bearing method. Fifteen transtibial unilateral amputees participated in the study. Two weight bearing and air pressure casting methods were utilized for their residual limbs. The diameters and circumferences of various areas of the residual limbs and positive casts were compared. The volumes of two types of casts were measured by a volumeter and compared. Visual Analogue Scale (VAS) was used to measure the sockets fit comfort. Circumferences at 10 and 15 cm below the patella on the casts were significantly smaller in air pressure casting method compared to the weight bearing method (p=0.00 and 0.01 respectively). The volume of the cast in air pressure method was lower than that of the weight bearing method (p=0.006). The amputees found the fit of the sockets prepared by air pressure method more comfortable than the weight bearing sockets (p=0.015). The air pressure casting reduced the circumferences of the distal portion of residual limbs which has more soft tissue and because of its snug fit it provided more comfort for amputees, according to the VAS measurements.

Gold nanorod linking to control plasmonic properties in solution and polymer nanocomposites.

PubMed

Ferrier, Robert C; Lee, Hyun-Su; Hore, Michael J A; Caporizzo, Matthew; Eckmann, David M; Composto, Russell J

2014-02-25

A novel, solution-based method is presented to prepare bifunctional gold nanorods (B-NRs), assemble B-NRs end-to-end in various solvents, and disperse linked B-NRs in a polymer matrix. The B-NRs have poly(ethylene glycol) grafted along its long axis and cysteine adsorbed to its ends. By controlling cysteine coverage, bifunctional ligands or polymer can be end-grafted to the AuNRs. Here, two dithiol ligands (C6DT and C9DT) are used to link the B-NRs in organic solvents. With increasing incubation time, the nanorod chain length increases linearly as the longitudinal surface plasmon resonance shifts toward lower adsorption wavelengths (i.e., red shift). Analogous to step-growth polymerization, the polydispersity in chain length also increases. Upon adding poly(ethylene glycol) or poly(methyl methacrylate) to chloroform solution with linked B-NR, the nanorod chains are shown to retain end-to-end linking upon spin-casting into PEO or PMMA films. Using quartz crystal microbalance with dissipation (QCM-D), the mechanism of nanorod linking is investigated on planar gold surfaces. At submonolayer coverage of cysteine, C6DT molecules can insert between cysteines and reach an areal density of 3.4 molecules per nm(2). To mimic the linking of Au NRs, this planar surface is exposed to cysteine-coated Au nanoparticles, which graft at 7 NPs per μm(2). This solution-based method to prepare, assemble, and disperse Au nanorods is applicable to other nanorod systems (e.g., CdSe) and presents a new strategy to assemble anisotropic particles in organic solvents and polymer coatings.

Gold Nanorod Linking to Control Plasmonic Properties in Solution and Polymer Nanocomposites

PubMed Central

2015-01-01

A novel, solution-based method is presented to prepare bifunctional gold nanorods (B-NRs), assemble B-NRs end-to-end in various solvents, and disperse linked B-NRs in a polymer matrix. The B-NRs have poly(ethylene glycol) grafted along its long axis and cysteine adsorbed to its ends. By controlling cysteine coverage, bifunctional ligands or polymer can be end-grafted to the AuNRs. Here, two dithiol ligands (C6DT and C9DT) are used to link the B-NRs in organic solvents. With increasing incubation time, the nanorod chain length increases linearly as the longitudinal surface plasmon resonance shifts toward lower adsorption wavelengths (i.e., red shift). Analogous to step-growth polymerization, the polydispersity in chain length also increases. Upon adding poly(ethylene glycol) or poly(methyl methacrylate) to chloroform solution with linked B-NR, the nanorod chains are shown to retain end-to-end linking upon spin-casting into PEO or PMMA films. Using quartz crystal microbalance with dissipation (QCM-D), the mechanism of nanorod linking is investigated on planar gold surfaces. At submonolayer coverage of cysteine, C6DT molecules can insert between cysteines and reach an areal density of 3.4 molecules per nm2. To mimic the linking of Au NRs, this planar surface is exposed to cysteine-coated Au nanoparticles, which graft at 7 NPs per μm2. This solution-based method to prepare, assemble, and disperse Au nanorods is applicable to other nanorod systems (e.g., CdSe) and presents a new strategy to assemble anisotropic particles in organic solvents and polymer coatings. PMID:24483622

Influence of Solutocapillary Convection on Macrovoid Defect Formation in Polymeric Membranes

NASA Technical Reports Server (NTRS)

Greenberg, Alan R.; Krantz, William B.; Todd, Paul

2003-01-01

The focus of this research project involved the dry-cast process for polymeric membrane formation, whereby evaporation of solvent from an initially homogeneous polymer/solvent/ nonsolvent solution results in phase separation and the formation of polymer-rich and polymer-lean phases. Under certain conditions the polymer-lean phase gives rise to very large and usually undesirable, tear-drop-shaped pores (size approx. 10 - 50 microns) termed macrovoids (MVs). Although in many cases the presence of MV pores has deleterious effects on membrane performance, there are a number of innovative applications where the presence of such pores is highly desirable. Although researchers have proposed a variety of mechanisms for MV formation over the past three decades, two main hypotheses are currently favored: one asserts that MV growth can be attributed solely to diffusion (the diffusive growth hypothesis), whereas the other states that solutocapillary convection (the SC hypothesis) at the MV interface contributes to growth. The overall goal of this research was to obtain a more comprehensive understanding of the fundamental mechanism of MV growth. This research incorporates a coupled modeling and experimental approach to test a solutocapillary convection hypothesis for the growth of macrovoid pores in polymeric membranes. Specifically, we utilized a modification of the first principles model developed by two of the PIs (ARG and WBK) for dry-cast CA membranes. For the experimental component, two separate and mutually complementary approaches were used to study MV growth. In the first, membranes cast in a zero-g environment aboard the NASA KC-135 aircraft were compared with those cast on the ground to assess the effect of the buoyancy force on membrane morphology and MV size and shape. In the second approach, videomicroscopy flow visualization (VMFV) was utilized to observe MV formation and growth in real time and to assess the effect of surface tension on the MV growth dynamics. As a result of these fundamental studies, our research group advanced a new hypothesis for MV pore development in polymeric membranes.

Synthesis and physicochemical characterization of chitin dihexanoate--A new biocompatible chitin derivative--In comparison to chitin dibutyrate.

PubMed

Skołucka-Szary, Karolina; Ramięga, Aleksandra; Piaskowska, Wanda; Janicki, Bartosz; Grala, Magdalena; Rieske, Piotr; Bartczak, Zbigniew; Piaskowski, Sylwester

2016-03-01

Chitin dihexanoate (DHCH) is the novel biocompatible and technologically friendly highly substituted chitin diester. Here we described optimization of DHCH and chitin dibutyrate (dibutyryl chitin, DBC) synthesis conditions (temperature and reaction time) to obtain desired polymers with high reaction yield, high substitution degree (close to 2) and appropriately high molecular weights. A two-step procedure, employing acidic anhydrides (hexanoic or butyric anhydride) as the acylation agent and methanesulfonic acid both as the catalyst and the reaction medium, was applied. Chemical structures of DBC and DHCH were confirmed by NMR ((1)H and (13)C) and IR investigations. Mechanical properties, thermogravimetric analysis, differential scanning calorimetry and biocompatibility (Neutral red uptake assay, Skin Sensitization and Irritation Tests) were assessed. Both polymers proved highly biocompatible (non-cytotoxic in vitro, non-irritating and non-allergic to skin) and soluble in several organic solvents (dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, acetone, ethanol and others). It is worth emphasizing that DHCH and DBC can be easily processed by solvent casting method and the salt-leaching method, what gives the opportunity to prepare highly porous structures, which can be further successfully applied as the material for wound dressings and scaffolds for tissue engineering. Copyright © 2015 Elsevier B.V. All rights reserved.

A Novel Mechanism for Chemical Sensing Based on Solvent-Fluorophore-Substrate Interaction: Highly Selective Alcohol and Water Sensor with Large Fluorescence Signal Contrast.

PubMed

Chung, Kyeongwoon; Yang, Da Seul; Jung, Jaehun; Seo, Deokwon; Kwon, Min Sang; Kim, Jinsang

2016-10-06

Differentiation of solvents having similar physicochemical properties, such as ethanol and methanol, is an important issue of interest. However, without performing chemical analyses, discrimination between methanol and ethanol is highly challenging due to their similarity in chemical structure as well as properties. Here, we present a novel type of alcohol and water sensor based on the subtle differences in interaction among solvent analytes, fluorescent organic molecules, and a mesoporous silica gel substrate. A gradual change in the chemical structure of the fluorescent diketopyrrolopyrrole (DPP) derivatives alters their interaction with the substrate and solvent analyte, which creates a distinct intermolecular aggregation of the DPP derivatives on the silica gel substrate depending on the solvent environment and produces a change in the fluorescence color and intensity as a sensory signal. The devised sensor device, which is fabricated with simple drop-casting of the DPP derivative solutions onto a silica gel substrate, exhibited a completely reversible fluorescence signal change with large fluorescence signal contrast, which allows selective solvent detection by simple optical observation with the naked eye under UV light. Superior selectivity of the alcohol and water sensor system, which can clearly distinguish among ethanol, methanol, ethylene glycol, and water, is demonstrated.

Characterization of 2-(2-Methoxyethoxy)ethanol Substituted Phosphazene Polymers Using Pervaporation, Solubility Parameters and Sorption Studies

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

Orme, Christopher Joseph; Klaehn, John Ray; Harrup, Mason Kurt

Two linear phosphazene polymers were synthesized with differing amounts of hydrophilic 2-(2-methoxyethoxy)ethanol (MEE) and hydrophobic 4-methoxyphenol (MEOP) substituted on the backbone. These high polymers were cast into membranes and their permeability to water, methanol, ethanol, and 2-propanol was evaluated as a function of temperature. An additional polymer with a low content of MEE was studied for water permeation and was characterized by trace flux. At higher levels of MEE on the backbone, fluxes of all solvents increased. Solubility also was found to increase with increasing MEE content for all solvents except water. Unexpectedly, water was found to be less solublemore » in the higher MEE polymer, although higher membrane fluxes were observed. Diffusion coefficients showed the following trend: methanol 2-propanol > ethanol water. Finally, the affinity of solvents and polymers was discussed in terms of Hansen solubility parameters.« less

Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.

PubMed

Krishnan, P Santhana Gopala; Joshi, Mangala; Bhargava, Prachur; Valiyaveettil, Suresh; He, Chaobin

2005-07-01

Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.

Glass transition in thin supported polystyrene films probed by temperature-modulated ellipsometry in vacuum.

PubMed

Efremov, Mikhail Yu; Kiyanova, Anna V; Last, Julie; Soofi, Shauheen S; Thode, Christopher; Nealey, Paul F

2012-08-01

Glass transition in thin (1-200 nm thick) spin-cast polystyrene films on silicon surfaces is probed by ellipsometry in a controlled vacuum environment. A temperature-modulated modification of the method is used alongside a traditional linear temperature scan. A clear glass transition is detected in films with thicknesses as low as 1-2 nm. The glass transition temperature (T(g)) shows no substantial dependence on thickness for coatings greater than 20 nm. Thinner films demonstrate moderate T(g) depression achieving 18 K for thicknesses 4-7 nm. Less than 4 nm thick samples are excluded from the T(g) comparison due to significant thickness nonuniformity (surface roughness). The transition in 10-20 nm thick films demonstrates excessive broadening. For some samples, the broadened transition is clearly resolved into two separate transitions. The thickness dependence of the glass transition can be well described by a simple 2-layer model. It is also shown that T(g) depression in 5 nm thick films is not sensitive to a wide range of experimental factors including molecular weight characteristics of the polymer, specifications of solvent used for spin casting, substrate composition, and pretreatment of the substrate surface.

Non-iridescent structural colors from uniform-sized SiO2 colloids

NASA Astrophysics Data System (ADS)

Topçu, Gökhan; Güner, Tuğrul; Demir, Mustafa M.

2018-05-01

Structural colors have recently attracted interest from diverse fields of research due to their ease of fabrication and eco-friendliness. These types of colors are, in principle, achieved by periodically arranged submicron-diameter colloidal particles. The interaction of light with a structure containing long-range ordered colloidal particles leads to coloration; this usually varies depending on the angle of observation (iridescence). However, the majority of the applications demand constant color that is independent of the viewing angle (non-iridescence). In this work, silica colloids were obtained using the Stöber method at different sizes from 150 to 300 nm in an alcoholic dispersion. The casting of the dispersion on a substrate leaves behind a photonic crystal showing a colorful iridescent film. However, centrifugation and redispersion of the SiO2 particles into fresh solvent may cause the formation of small, aggregated silica domains in the new dispersion. The casting of this dispersion allows for the development of photonic glass, presumably due to the accumulation of aggregates showing stable colloidal film independent of viewing angle. Moreover, depending on the size of the silica colloids, non-iridescent photonic glasses with various colors (violet, blue, green, and orange) are obtained.

Polyethersulfone/polyacrylonitrile blended ultrafiltration membranes: preparation, morphology and filtration properties.

PubMed

Pasaoglu, Mehmet Emin; Guclu, Serkan; Koyuncu, Ismail

Polyethersulfone (PES)/polyacrylonitrile (PAN) membranes have been paid attention among membrane research subjects. However, very few studies are included in the literature. In our study, asymmetric ultrafiltration (UF) membranes were prepared from blends of PES/PAN with phase inversion method using water as coagulation bath. Polyvinylpyrrolidone (PVP) with Mw of 10,000 Da was used as pore former agent. N,N-dimethylformamide was used as solvent. The effects of different percentage of PVP and PES/PAN composition on morphology and water filtration properties were investigated. Membrane performances were examined using pure water and lake water filtration studies. Performances of pure water were less with the addition of PAN into the PES polymer casting solutions. However, long-term water filtration tests showed that PES/PAN blend membranes anti-fouling properties were much higher than the neat PES membranes. The contact angles of PES/PAN membranes were lower than neat PES membranes because of PAN addition in PES polymer casting solutions. Furthermore, it was found that PES/PAN blend UF membranes' dynamic mechanical analysis properties in terms of Young's modules were less than neat PES membrane because of decreasing amount of PES polymer.

Dispersion Morphology of Poly(methyl acrylate)/Silica Nanocomposites

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

D Janes; J Moll; S Harton

Nearly monodisperse poly(methyl acrylate) (PMA) and spherical SiO{sub 2} nanoparticles (NP, d = 14 {+-} 4 nm) were co-cast from 2-butanone, a mutually good solvent and a displacer of adsorbed PMA from silica. The effects of NP content and post-casting sample history on the dispersion morphology were found by small-angle X-ray scattering supplemented by transmission electron microscopy. Analysis of the X-ray results show that cast and thermally annealed samples exhibited a nearly random particle dispersion. That the same samples, prior to annealing, were not well-dispersed is indicative of thermodynamic miscibility during thermal annealing over the range of NP loadings studied.more » A simple mean-field thermodynamic model suggests that miscibility results primarily from favorable polymer segment/NP surface interactions. The model also indicates, and experiments confirm, that subsequent exposure of the composites to the likely displacer ethyl acetate results in entropic destabilization and demixing into NP-rich and NP-lean phases.« less

The Wettability of LaRC Colorless Polyimide Resins on Casting Surfaces

NASA Technical Reports Server (NTRS)

Miner, Gilda A.; Stoakley, Diane M.; St.Clair, Anne K.; Gierow, Paul A.; Bates, Kevin

1997-01-01

Two colorless polyimides developed at NASA Langley Research Center, LaRC -CP1 and LaRC -CP2, are noted for being optically transparent, resistant to radiation, and soluble in the imide form. These materials may be used to make transparent, thin polymer films for building large space reflector/collector inflatable antennas, solar arrays, radiometers, etc. Structures such as these require large area, seamless films produced via spin casting or spray coating the soluble imide on a variety of substrates. The ability of the soluble imide to wet and spread over the mandrel or casting substrate is needed information for processing these structures with minimum waste and reprocessing, thereby, reducing the production costs. The wettability of a liquid is reported as the contact angle of the solid/liquid system. This fairly simple measurement is complicated by the porosity and the amount of contamination of the solid substrate. This work investigates the effect of inherent viscosity, concentration of polyimide solids, and solvent type on the wettability of various curing surfaces.

Characterization of cobalt(II) chloride-modified condensation polyimide films

NASA Technical Reports Server (NTRS)

Rancourt, J. D.; Taylor, L. T.

1988-01-01

The effect of solvent extraction on the properties of cobalt(II) chloride-modified polyimide films was investigated. Solvent-cast films were prepared from solutions of cobalt chloride in poly(amide acid)/N,N-dimethylacetamide (DMAc) and were subsequently dried and cured in static air, forced air, or inert gas ovens with controlled humidity. The films were extracted by either of the three processes (1) soaking in a tray with distilled water at room temperature, (2) soxhlett extraction with distilled water, or (3) soxhell extraction with DMAc. Extraction with DMAc was found to remove both cobalt and chlorine from the films and to slightly increase bulk thermal stability and both surface resistivity and electrical resistivity.

Robust Guar Gum/Cellulose Nanofibrils Multilayer Films with Good Barrier Properties.

PubMed

Dai, Lei; Long, Zhu; Chen, Jie; An, Xingye; Cheng, Dong; Khan, Avik; Ni, Yonghao

2017-02-15

The pursuit of sustainable functional materials requires development of materials based on renewable resources and efficient fabrication methods. Hereby, we fabricated all-polysaccharides multilayer films using cationic guar gum (CGG) and anionic cellulose nanofibrils (i.e., TEMPO-oxidized cellulose nanofibrils, TOCNs) through a layer-by-layer casting method. This technique is based on alternate depositions of oppositely charged water-based CGG and TOCNs onto laminated films. The resultant polyelectrolyte multilayer films were transparent, ductile, and strong. More importantly, the self-standing films exhibited excellent gas (water vapor and oxygen) and oil barrier performances. Another outstanding feature of these resultant films was their resistance to various organic solvents including methanol, acetone, N,N-dimethylacetamide (DMAc) and tetrahydrofuran (THF). The proposed film fabrication process is environmentally benign, cost-effective, and easy to scale-up. The developed CGG/TOCNs multilayer films can be used as a renewable material for industrial applications such as packaging.

In Situ Cross-Linking of Polyvinyl Alcohol Films

NASA Technical Reports Server (NTRS)

Philipp, W. H.; Shu, L. C.; May, C. E.

1984-01-01

Films or impregnated matrices readily made from aqueous polyvinyl alcohol solution. Controlled thickness films made by casting precise quantities of aqueous polymer solution on smooth surface, allowing water to evaporate and then removing film. Composite separators formed in similar fashion by impregnating cloth matrix with polyvinyl alcohol solution and drying composite. Insoluble thin hydrophilic membranes made from aqueous systems, and use of undesirable organic solvents not required.

Nuclear Weapons. National Nuclear Security Administration’s Plans for Its Uranium Processing Facility Should Better Reflect Funding Estimates and Technology Readiness

DTIC Science & Technology

2010-11-01

metal. Recovery extraction centrifugal contactors A process that uses solvent to extract uranium for purposes of purification. Agile machining A...extraction centrifugal contactors 5 6 Yes 6 No Agile machining 5 5 No 6 No Chip management 5 6 Yes 6 No Special casting 3 6 Yes 6 No Source: GAO

The production of ultrathin polyimide films for the solar sail program and Large Space Structures Technology (LSST): A feasibility study

NASA Technical Reports Server (NTRS)

Forester, R. H.

1978-01-01

Polyimide membranes of a thickness range from under 0.01 micron m to greater than 1 micron m can be produced at an estimated cost of 50 cents per sq m (plus the cost of the polymer). The polymer of interest is dissolved in a solvent which is solube in water. The polymer or casting solution is allowed to flow down an inclined ramp onto a water surface where a pool of floating polymer develops. The solvent dissolves into the water lowering the surface tension of the water on equently, the contact angle of the polymer pool is very low and the edge of the pool is very thin. The solvent dissolves from this thin region too rapidly to be replenished from the bulk of the pool and a solid polymer film forms. Firm formation is rapid and spontaneous and the film spreads out unaided, many feet from the leading edge of the pool. The driving force for this process is the exothermic solution of the organic solvent from the polymer solution into the water.

Development and evaluation of a digital dental modeling method based on grating projection and reverse engineering software.

PubMed

Zhou, Qin; Wang, Zhenzhen; Chen, Jun; Song, Jun; Chen, Lu; Lu, Yi

2016-01-01

For reasons of convenience and economy, attempts have been made to transform traditional dental gypsum casts into 3-dimensional (3D) digital casts. Different scanning devices have been developed to generate digital casts; however, each has its own limitations and disadvantages. The purpose of this study was to develop an advanced method for the 3D reproduction of dental casts by using a high-speed grating projection system and noncontact reverse engineering (RE) software and to evaluate the accuracy of the method. The methods consisted of 3 main steps: the scanning and acquisition of 3D dental cast data with a high-resolution grating projection system, the reconstruction and measurement of digital casts with RE software, and the evaluation of the accuracy of this method using 20 dental gypsum casts. The common anatomic landmarks were measured directly on the gypsum casts with a Vernier caliper and on the 3D digital casts with the Geomagic software measurement tool. Data were statistically assessed with the t test. The grating projection system had a rapid scanning speed, and smooth 3D dental casts were obtained. The mean differences between the gypsum and 3D measurements were approximately 0.05 mm, and no statistically significant differences were found between the 2 methods (P>.05), except for the measurements of the incisor tooth width and maxillary arch length. A method for the 3D reconstruction of dental casts was developed by using a grating projection system and RE software. The accuracy of the casts generated using the grating projection system was comparable with that of the gypsum casts. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Europium containing red light-emitting fibers made by electrohydrodynamic casting

NASA Astrophysics Data System (ADS)

Gan, Yong X.; Panahi, Niousha; Yu, Christina; Gan, Jeremy B.; Cheng, Wanli

2018-05-01

Red light-emitting polymeric micro- and nanofibers were made by electrohydrodynamic co-casting of two fluids. One fluid contains a 10 wt% concentration europium (III) complex dissolved in a dimethylformamide (DMF) solvent. The europium complex, an Eu3+ compound with the nominal formula of Eu(BA)3phen/PAN, consists of polyacrylonitrile (PAN), 1,10-phenanthroline (phen), and benzoic acid (BA). The other fluid consists of iron metal oxide nanoparticles dispersed in a solution containing 10 wt% polyacrylonitrile polymer in DMF solvent. The two fluids were electrohydrodynamically co-cast onto a soft tissue paper using a stainless steel coaxial nozzle. The intensity of the electric field used for the co-casting was 1.5 kV/cm. Scanning electron microscopic observation on the fibers obtained from the co-casting was made. The size of the fibers ranges from several hundreds of nanometers to several microns. Energy dispersive X-ray spectroscopic analysis of the fibers confirmed that the major elements included C, O, Fe, and Eu. The fluorescence of the two types of fibers was tested under the excitation of a UV light source. It was found that when the europium complex-containing solution was the sheath fluid and the iron-containing solution was the core, the prepared fibers showed red light-emitting behavior under ultraviolet light. Time-dependent fluorescence shows the two-stage decaying behavior. The first stage lasts about 2000 s and the intensity of fluorescence decreases linearly. The second stage reveals the slow decaying behavior and it lasts longer than 3 h. Based on the bi-exponential data fitting using a processing MATLAB code, the fluorescence-related constants were extracted. A bi-exponential formula was proposed to describe the time-dependent fluorescence behavior of the fiber made by the europium complex-containing solution as the sheath fluid. The decaying in the fluorescence shows two different stages. The first stage lasts about 2000 s and it is characterized by a fast decaying model. The intensity of fluorescence decreases linearly. The second stage has a slow decaying feature. It takes over 3 h for the fluorescence to die out completely. Bi-exponential data fitting shows that the time constant for the decay of fluorescence is about 10,000 s.

Improved Net-Level Filling And Finishing Of Large Castings

NASA Technical Reports Server (NTRS)

Johnson, Erik P.; Brown, Richard F.

1995-01-01

Improved method of vacuum casting of large, generally cylindrical objects to net sizes and shapes reduces amount of direct manual labor by workers in proximity to cast material. Original application for which method devised is fabrication of solid rocket-motor segments containing solid propellant, wherein need to minimize exposure of workers to propellant material being cast. Improved method adaptable to other applications involving large castings of toxic, flammable, or otherwise hazardous materials.

Osteochondral Repair Using Porous Three-dimensional Nanocomposite Scaffolds in a Rabbit Model

PubMed Central

ŻYLIŃSKA, BEATA; STODOLAK-ZYCH, EWA; SOBCZYŃSKA-RAK, ALEKSANDRA; SZPONDER, TOMASZ; SILMANOWICZ, PIOTR; ŁAŃCUT, MIROSŁAW; JAROSZ, ŁUKASZ; RÓŻAŃSKI, PAWEŁ; POLKOWSKA, IZABELA

2017-01-01

Aim: To evaluate the utility of a novel nanocomposite biomaterial consisting of poly-L/D-lactide, and hydroxyapatite bioceramics, enriched with sodium alginate in articular cartilage defect treatment. Materials and Methods: The biomaterial was prepared using the method of solvent casting and particle leaching. The study was conducted on 20 New Zealand White rabbits. Experimental osteochondral defects were created in the femoral trochlear grooves and filled with biomaterials. In control groups, the defects were left to spontaneously heal. The quality of newly-formed tissue was evaluated on the basis of macroscopic and histological assessment. Additionally the level of osteogenic and cartilage degradation markers were measured. Results: The majority of the defects from the treatment group were covered with tissue similar in structure and colour to healthy cartilage, whereas in the control group, tissue was uneven, and not integrated into the surrounding cartilage. Conclusion: The results obtained validate the choice of biomaterial used in this study as well as the method of its application. PMID:28882956

Correlating highpower conversion efficiency of PTB7:PC 71BM inverted organic solar cells with nanoscale structures [Unraveling the correlation between the structural aspects and power conversion efficiency in PTB7:PC 71BM inverted organic solar cells

DOE PAGES

Das, Sanjib; Browning, Jim; Gu, Gong; ...

2015-07-16

Advances in materials design and device engineering led to inverted organic solar cells (i-OSCs) with superior power conversion efficiencies (PCEs) to their conventional counterparts, in addition to the well-known better ambient stability. Despite the significant progress, however, it has so far been unclear how the morphologies of the photoactive layer and its interface with the cathode modifying layer impact device performance. Here, we report an in-depth morphology study of the i-OSC active and cathode modifying layers, employing a model system with the well-established bulk-heterojunction, PTB7:PC 71BM as the active layer and poly-[(9,9-bis(3 -( N,N-dimethylamino)propyl)-2,7-fluorene)- alt-2,7-(9,9-dioctylfluorene)] (PFN) as the cathode surfacemore » modifying layer. We have also identified the role of a processing additive, 1,8-diiodooctane (DIO), used in the spin-casting of the active layer to increase PCE. Using a variety of characterization techniques, we demonstrate that the high PCEs of i-OSCs are due to the smearing (diffusion) of electron-accepting PC 71BM into the PFN layer, resulting in improved electron transport. The PC 71BM diffusion occurs after spin-casting the active layer onto the PFN layer, when residual solvent molecules act as a plasticizer. Furthermore, the DIO additive, with a higher boiling point than the host solvent, has a longer residence time in the spin-cast active layer, resulting in more PC 71BM smearing and therefore more efficient electron transport. This work provides important insight and guidance to further enhancement of i-OSC performance by materials and interface engineering.« less

Controlled Assembly of Lignocellulosic Biomass Components and Properties of Reformed Materials

DOE PAGES

Wang, Jing; Boy, Ramiz; Nguyen, Ngoc A.; ...

2017-07-25

Reforming whole lignocellulosic biomass into value-added materials has yet to be achieved mainly due to the infusible nature of biomass and its recalcitrance to dissolve in common organic solvents. Recently, the solubility of biomass in ionic liquids (ILs) has been explored to develop all-lignocellulosic materials; however, efficient dissolution and therefore production of value-added materials with desired mechanical properties remain a challenge. This article presents an approach to producing high-performance lignocellulosic films from hybrid poplar wood. An autohydrolysis step that removes ≤50% of the hemicellulose fraction is performed to enhance biomass solvation in 1-ethyl-3-methyl imidazolium acetate ([C2mim][OAc]). The resulting biomass–IL solutionmore » is then cast into free-standing films using different coagulating solvents, yet preserving the polymeric nature of the biomass constituents. Methanol coagulated films exhibit a cocontinuous 3D-network structure with dispersed domains of less than 100 nm. The consolidated films with controllable morphology and structural order demonstrate tensile properties better than those of quasi-isotropic wood. Here, the methods for producing these biomass derivatives have potential for fabricating novel green materials with superior performance from woody and grassy biomass.« less

Enhancing the Liquid-Phase Exfoliation of Graphene in Organic Solvents upon Addition of n-Octylbenzene

PubMed Central

Haar, Sébastien; El Gemayel, Mirella; Shin, Yuyoung; Melinte, Georgian; Squillaci, Marco A.; Ersen, Ovidiu; Casiraghi, Cinzia; Ciesielski, Artur; Samorì, Paolo

2015-01-01

Due to a unique combination of electrical and thermal conductivity, mechanical stiffness, strength and elasticity, graphene became a rising star on the horizon of materials science. This two-dimensional material has found applications in many areas of science ranging from electronics to composites. Making use of different approaches, unfunctionalized and non-oxidized graphene sheets can be produced; among them an inexpensive and scalable method based on liquid-phase exfoliation of graphite (LPE) holds potential for applications in opto-electronics and nanocomposites. Here we have used n-octylbenzene molecules as graphene dispersion-stabilizing agents during the graphite LPE process. We have demonstrated that by tuning the ratio between organic solvents such as N-methyl-2-pyrrolidinone or ortho-dichlorobenzene, and n-octylbenzene molecules, the concentration of exfoliated graphene can be enhanced by 230% as a result of the high affinity of the latter molecules for the basal plane of graphene. The LPE processed graphene dispersions were further deposited onto solid substrates by exploiting a new deposition technique called spin-controlled drop casting, which was shown to produce uniform highly conductive and transparent graphene films. PMID:26573383

Riser Feeding Evaluation Method for Metal Castings Using Numerical Analysis

NASA Astrophysics Data System (ADS)

Ahmad, Nadiah

One of the design aspects that continues to create a challenge for casting designers is the optimum design of casting feeders (risers). As liquid metal solidifies, the metal shrinks and forms cavities inside the casting. In order to avoid shrinkage cavities, risers are added to the casting shape to supply additional molten metal when shrinkage occurs during solidification. The shrinkage cavities in the casting are compensated by controlling the cooling rate to promote directional solidification. This control can be achieved by designing the casting such that the cooling begins at the sections that are farthest away from the risers and ends at the risers. Therefore, the risers will solidify last and feed the casting with the molten metal. As a result, the shrinkage cavities formed during solidification are in the risers which are later removed from the casting. Since casting designers have to usually go through iterative processes of validating the casting designs which are very costly due to expensive simulation processes or manual trials and errors on actual casting processes, this study investigates more efficient methods that will help casting designers utilize their casting experiences systematically to develop good initial casting designs. The objective is to reduce the casting design method iterations; therefore, reducing the cost involved in that design processes. The aim of this research aims at finding a method that can help casting designers design effective risers used in sand casting process of aluminum-silicon alloys by utilizing the analysis of solidification simulation. The analysis focuses on studying the significance of pressure distribution of the liquid metal at the early stage of casting solidification, when heat transfer and convective fluid flow are taken into account in the solidification simulation. The mathematical model of casting solidification was solved using the finite volume method (FVM). This study focuses to improve our understanding of the feeding behavior in aluminum-silicon alloys and the effective feeding by considering the pressure gradient distribution of the molten metal at casting dendrite coherency point. For this study, we will identify the relationship between feeding efficiency, shrinkage behavior and how the change in riser size affects the pressure gradient in the casting. This understanding will be used to help in the design of effective risers.

Formulation and Testing of Paraffin-Based Solid Fuels Containing Energetic Additives for Hybrid Rockets

NASA Technical Reports Server (NTRS)

Larson, Daniel B.; Boyer, Eric; Wachs,Trevor; Kuo, Kenneth K.; Story, George

2012-01-01

Many approaches have been considered in an effort to improve the regression rate of solid fuels for hybrid rocket applications. One promising method is to use a fuel with a fast burning rate such as paraffin wax; however, additional performance increases to the fuel regression rate are necessary to make the fuel a viable candidate to replace current launch propulsion systems. The addition of energetic and/or nano-sized particles is one way to increase mass-burning rates of the solid fuels and increase the overall performance of the hybrid rocket motor.1,2 Several paraffin-based fuel grains with various energetic additives (e.g., lithium aluminum hydride (LiAlH4) have been cast in an attempt to improve regression rates. There are two major advantages to introducing LiAlH4 additive into the solid fuel matrix: 1) the increased characteristic velocity, 2) decreased dependency of Isp on oxidizer-to-fuel ratio. The testing and characterization of these solid-fuel grains have shown that continued work is necessary to eliminate unburned/unreacted fuel in downstream sections of the test apparatus.3 Changes to the fuel matrix include higher melting point wax and smaller energetic additive particles. The reduction in particle size through various methods can result in more homogeneous grain structure. The higher melting point wax can serve to reduce the melt-layer thickness, allowing the LiAlH4 particles to react closer to the burning surface, thus increasing the heat feedback rate and fuel regression rate. In addition to the formulation of LiAlH4 and paraffin wax solid-fuel grains, liquid additives of triethylaluminum and diisobutylaluminum hydride will be included in this study. Another promising fuel formulation consideration is to incorporate a small percentage of RDX as an additive to paraffin. A novel casting technique will be used by dissolving RDX in a solvent to crystallize the energetic additive. After dissolving the RDX in a solvent chosen for its compatibility with both paraffin and RDX, the mixture will be combined with the melted paraffin. With the melting point of the paraffin far below the decomposition temperature of the RDX, the solvent will be boiled off, leaving the crystallized RDX embedded in the paraffin. At low percentages of RDX additive and with crystallized RDX surrounded by paraffin, the fuel grains will remain inert, maintaining a key benefit of hybrids in the safety of the solid fuel.

Conversion of sustained release omeprazole loaded buccal films into fast dissolving strips using supercritical carbon dioxide (scCO2) processing, for potential paediatric drug delivery.

PubMed

Khan, Sajjad; Trivedi, Vivek; Mitchell, John; Boateng, Joshua S

2016-10-10

This study involves the development of thin oral solvent cast films for the potential delivery of the proton pump inhibitor, omeprazole (OME) via the buccal mucosa for paediatric patients. OME containing films were prepared from ethanolic gels (1% w/w) of metolose (MET) with polyethylene glycol (PEG 400) (0.5% w/w) as plasticiser, and L-arginine (l-arg) (0.2% w/w) as a stabilizer and dried in an oven at 40°C. The blank and drug loaded films were divided into two groups, one group was subjected to supercritical carbon dioxide (scCO2) treatment and the other group untreated. The untreated and scCO2 treated films were then characterised using differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, hydration (swelling), mucoadhesion and in vitro drug dissolution studies. Treatment of the solvent cast films with scCO2 caused significant changes to the functional and physical properties of the MET films. The original drug loaded MET films showed a sustained release of OME (1h), whereas scCO2 treatment of the formulations resulted in fast dissolving films with >90% drug release within 15min. Copyright © 2016 Elsevier B.V. All rights reserved.

Macrovoid Defect Growth during Evaporative Casting of Polymeric Membranes

NASA Technical Reports Server (NTRS)

Greenberg, A. R.; Khare, V. P.; Zartman, J.; Krantz, W. B.; Todd, P.

2003-01-01

Macrovoid (MV) formation is a significant problem in evaporatively cast polymeric membranes. MVs are large, elongated or teardrop-shaped pores (10-50 micron) that can impair membrane structural integrity. Although MVs have been extensively studied, there is no general agreement on the mechanisms governing MV growth. Recently, our research group has formulated the solutocapillary convection (SC) hypothesis, which contends that MV growth involves three principal forces: a Marangoni force generated by surface tension gradients within the MV interface, a viscous drag force, and a gravitationally induced body force. Two sets of complementary experiments were conducted to test the SC hypothesis. Ground-based videomicroscopy flow-visualization (VMFV) was utilized to measure the flow velocities at the MV-casting solution interface and deep within the casting solution. The measurements were performed with casting solutions containing 10 wt% cellulose acetate (CA), 30 wt% H2O, 60 wt% acetone, and 200- ppm TiO2 particles for flow visualization, and the surface tension was controlled by surfactant addition. Qualitatively, the experiments indicated that MV growth occurs in three distinct phases: (1) a very rapid initial growth period, (2) a much slower growth phase, and (3) absorption of selected MVs into the expanding demixed region. The presence of tracer particles inside the MVs suggests the presence of a convective flow, which transfers the particles from the bulk solution to the MV interior. Although the VMFV experiments did not establish any surfactant effect on the interfacial velocities, a statistically significant effect on the MV number density was observed. In the second set of experiments, membranes were cast aboard a KC-135 aircraft under 0-g and 2-g conditions. Despite careful attention to the design and fabrication of the membrane casting apparatus (MCA), several problems were encountered, the most significant of which was the contamination of the casting solution by the activated carbon particles used for solvent absorption.

Electronic gap sensor and method

DOEpatents

Williams, R.S.; King, E.L.; Campbell, S.L.

1991-08-06

Disclosed are an apparatus and method for regulating the gap between a casting nozzle and a casting wheel in which the gap between the casting nozzle and the casting wheel is monitored by means of at least one sensing element protruding from the face of the casting nozzle. The sensing element is preferably connected to a voltage source and the casting wheel grounded. When the sensing element contacts the casting wheel, an electric circuit is completed. The completion of the circuit can be registered by an indicator, and the presence or absence of a completed circuit indicates the relative position of the casting nozzle to the casting wheel. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. 5 figures.

Electronic gap sensor and method

DOEpatents

Williams, Robert S.; King, Edward L.; Campbell, Steven L.

1991-01-01

An apparatus and method for regulating the gap between a casting nozzle and a casting wheel in which the gap between the casting nozzle and the casting wheel is monitored by means of at least one sensing element protruding from the face of the casting nozzle. The sensing element is preferably connected to a voltage source and the casting wheel grounded. When the sensing element contacts the casting wheel, an electric circuit is completed. The completion of the circuit can be registered by an indicator, and the presence or absence of a completed circuit indicates the relative position of the casting nozzle to the casting wheel. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces.

Cast-In-Situ, Large-Sized Monolithic Silica Xerogel Prepared in Aqueous System.

PubMed

Ding, Wenhui; Wang, Xiaodong; Chen, Dong; Li, Tiemin; Shen, Jun

2018-05-15

This paper reports the preparation of cast-in-situ, large-sized monolithic silica xerogels by a two-step acid⁻base catalyzed approach under ambient pressure drying. Low-cost industrial silica sol and deionized water were used as the silicon source and the solvent, respectively. Hexadecetyltrimethylammonium bromide (CTAB) was used as a modification agent. Different amounts of polyethylene glycol 400 (PEG400) was added as a pore-forming agent. The prepared silica xerogels under ambient pressure drying have a mesoporous structure with a low density of 221 mg·cm -3 and a thermal conductivity of 0.0428 W·m -1 ·K -1 . The low-cost and facile preparation process, as well as the superior performance of the monolithic silica xerogels make it a promising candidate for industrial thermal insulation materials.

Enhanced performance of ferroelectric-based all organic transistors and capacitors through choice of solvent

NASA Astrophysics Data System (ADS)

Knotts, Grant; Bhaumik, Anagh; Ghosh, Kartik; Guha, Suchismita

2014-03-01

We examine the role of solvents in the performance of pentacene devices using the ferroelectric copolymer poly(vinylidene fluoride-co-trifluoroethylene) (PVDF-TrFe) as a gate insulating layer. High dipole moment solvents such as dimethyl sulfoxide used to dissolve the copolymer for spin casting increase the charge carrier mobility in field-effect transistors by nearly an order of magnitude as compared to lower dipole moment solvents. The polarization in Al/PVDF-TrFe/Au metal-ferroelectric-metal devices is also investigated. An increase in remnant polarization of ~ 20% is observed in the sample using dimethyl sulfoxide as the ferroelectric solvent. Interestingly, at low applied electric fields of ~ 100 MV/m a remnant polarization is seen in the high dipole moment device that is nearly 3.5 times larger than the value observed in the lower dipole moment samples, suggesting that the degree of dipolar order is higher at low operating voltages for the high dipole moment device. Detailed analysis of the capacitance characteristics of metal-insulator-semiconductor structure is performed. The density of interface trap states is nearly an order of magnitude lower for the high dipole moment device. This work was supported by National Science Foundation under Grant No. ECCS-1305642.

Method of reducing the green density of a slip cast article

DOEpatents

Mangels, John A.; Dickie, Ray A.

1985-01-01

The method disclosed in this specification is one of reducing the green density of an article cast in a slip casting operation. The article is cast from a casting slip containing silicon metal particles, yttrium containing particles, and a small amount of a fluoride salt which is effective to suppress flocculation of the silicon metal particles by y.sup.+3 ions derived from the yttrium containing particles. The method is characterized by the following step. A small amount of compound which produces a cation which will partly flocculate the particles of silicon metal is added to the casting slip. The small amount of this compound is added so that when the casting slip is slip cast into a casting mold, the partly flocculated particles of silicon will interrupt an otherwise orderly packing of the particles of silicon and particles of yttrium. In this manner, the green density of the slip cast article is reduced and the article may be more easily nitrided.

Comparative study of two commercially pure titanium casting methods

PubMed Central

RODRIGUES, Renata Cristina Silveira; FARIA, Adriana Claudia Lapria; ORSI, Iara Augusta; de MATTOS, Maria da Gloria Chiarello; MACEDO, Ana Paula; RIBEIRO, Ricardo Faria

2010-01-01

The interest in using titanium to fabricate removable partial denture (RPD) frameworks has increased, but there are few studies evaluating the effects of casting methods on clasp behavior. Objective This study compared the occurrence of porosities and the retentive force of commercially pure titanium (CP Ti) and cobalt-chromium (Co-Cr) removable partial denture circumferential clasps cast by induction/centrifugation and plasma/vacuum-pressure. Material and Methods 72 frameworks were cast from CP Ti (n=36) and Co-Cr alloy (n=36; control group). For each material, 18 frameworks were casted by electromagnetic induction and injected by centrifugation, whereas the other 18 were casted by plasma and injected by vacuum-pressure. For each casting method, three subgroups (n=6) were formed: 0.25 mm, 0.50 mm, and 0.75 mm undercuts. The specimens were radiographed and subjected to an insertion/removal test simulating 5 years of framework use. Data were analyzed by ANOVA and Tukey's to compare materials and cast methods (α=0.05). Results Three of 18 specimens of the induction/centrifugation group and 9 of 18 specimens of plasma/vacuum-pressure cast presented porosities, but only 1 and 7 specimens, respectively, were rejected for simulation test. For Co-Cr alloy, no defects were found. Comparing the casting methods, statistically significant differences (p<0.05) were observed only for the Co-Cr alloy with 0.25 mm and 0.50 mm undercuts. Significant differences were found for the 0.25 mm and 0.75 mm undercuts dependent on the material used. For the 0.50 mm undercut, significant differences were found when the materials were induction casted. Conclusion Although both casting methods produced satisfactory CP Ti RPD frameworks, the occurrence of porosities was greater in the plasma/vacuum-pressure than in the induction/centrifugation method, the latter resulting in higher clasp rigidity, generating higher retention force values. PMID:21085805

Development of a new casting method to fabricate U–Zr alloy containing minor actinides

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

Jong Hwan Kim; Hoon Song; Hyung Tae Kim

2014-01-01

Metal fuel slugs of U–Zr alloys for a sodium-cooled fast reactor (SFR) have conventionally been fabricated using an injection casting method. However, casting alloys containing volatile radioactive constituents, such as Am, are problematic in a conventional injection casting method. As an alternative fabrication method, low pressure gravity casting has been developed. Casting soundness, microstructural characteristics, alloying composition, density, and fuel losses were evaluated for the following as-cast fuel slugs: U–10 wt% Zr, U–10 wt% Zr–5 wt% RE, and U–10 wt% Zr–5 wt% RE–5 wt% Mn. The U and Zr contents were uniform throughout the matrix, and impurities such as oxyen,more » carbon, and nitrogen satisfied the specification of total impurities less than 2,000 ppm. The appearance of the fuel slugs was generally sound, and the internal integrity was shown to be satisfactory based on gamma-ray radiography. In a volatile surrogate casting test, the U–Zr–RE–Mn fuel slug showed that nearly all of the manganese was retained when casting was done under an inert atmosphere.« less

[Exploring a new method for superimposition of pre-treatment and post-treatment mandibular digital dental casts in adults].

PubMed

Dai, F F; Liu, Y; Xu, T M; Chen, G

2018-04-18

To explore a cone beam computed tomography (CBCT)-independent method for mandibular digital dental cast superimposition to evaluate three-dimensional (3D) mandibular tooth movement after orthodontic treatment in adults, and to evaluate the accuracy of this method. Fifteen post-extraction orthodontic treatment adults from the Department of Orthodontics, Peking University School and Hospital of Stomatology were included. All the patients had four first premolars extracted, and were treated with straight wire appliance. The pre- and post-treatment plaster dental casts and craniofacial CBCT scans were obtained. The plaster dental casts were transferred to digital dental casts by 3D laser scanning, and lateral cephalograms were created from the craniofacial CBCT scans by orthogonal projection. The lateral cephalogram-based mandibular digital dental cast superimposition was achieved by sequential maxillary dental cast superimposition registered on the palatal stable region, occlusal transfer, and adjustment of mandibular rotation and translation obtained from lateral cephalogram superimposition. The accuracy of the lateral cephalogram-based mandibular digital dental cast superimposition method was evaluated with the CBCT-based mandibular digital dental cast superimposition method as the standard reference. After mandibular digital dental cast superimposition using both methods, 3D coordinate system was established, and 3D displacements of the lower bilateral first molars, canines and central incisors were measured. Differences between the two superimposition methods in tooth displacement measurements were assessed using the paired t-test with the level of statistical significance set at P<0.05. No significant differences were found between the lateral cephalogram-based and CBCT-based mandibular digital dental cast superimposition methods in 3D displacements of the lower first molars, and sagittal and vertical displacements of the canines and central incisors; transverse displacements of the canines and central incisors differed by (0.3±0.5) mm with statistical significance. The lateral cephalogram-based mandibular digital dental cast superimposition method has the similar accuracy as the CBCT-based mandibular digital dental cast superimposition method in 3D evaluation of mandibular orthodontic tooth displacement, except for minor differences for the transverse displacements of anterior teeth. This method is applicable to adult patients with conventional orthodontic treatment records, especially the previous precious orthodontic data in the absence of CBCT scans.

25 CFR 217.6 - Method of casting votes.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 25 Indians 1 2010-04-01 2010-04-01 false Method of casting votes. 217.6 Section 217.6 Indians.... § 217.6 Method of casting votes. Within 30 days after an issue and any analysis provided for in §§ 217.4... superintendent in writing of the number of votes cast for and against the proposed or alternative solutions. If...

Method and apparatus for in-situ drying investigation and optimization of slurry drying methodology

DOEpatents

Armstrong, Beth L.; Daniel, Claus; Howe, Jane Y.; Kiggans, Jr, James O.; Sabau, Adrian S.; Wood, III, David L.; Kalnaus, Sergiy

2016-05-10

A method of drying casted slurries that includes calculating drying conditions from an experimental model for a cast slurry and forming a cast film. An infrared heating probe is positioned on one side of the casted slurry and a thermal probe is positioned on an opposing side of the casted slurry. The infrared heating probe may control the temperature of the casted slurry during drying. The casted slurry may be observed with an optical microscope, while applying the drying conditions from the experimental model. Observing the casted slurry includes detecting the incidence of micro-structural changes in the casted slurry during drying to determine if the drying conditions from the experimental model are optimal.

ToxCast HTS Assay Development and Retrofitting: Strategies ...

EPA Pesticide Factsheets

A presentation to EC JRC partners on new ToxCast HTS assay methods and strategies to address current limitations to HTS methods Slide presentation to EC JRC partners on new ToxCast HTS assay methods and strategies to address current limitations to HTS methods.

Three-dimensional printing of freeform helical microstructures: a review.

PubMed

Farahani, R D; Chizari, K; Therriault, D

2014-09-21

Three-dimensional (3D) printing is a fabrication method that enables creation of structures from digital models. Among the different structures fabricated by 3D printing methods, helical microstructures attracted the attention of the researchers due to their potential in different fields such as MEMS, lab-on-a-chip systems, microelectronics and telecommunications. Here we review different types of 3D printing methods capable of fabricating 3D freeform helical microstructures. The techniques including two more common microfabrication methods (i.e., focused ion beam chemical vapour deposition and microstereolithography) and also five methods based on computer-controlled robotic direct deposition of ink filament (i.e., fused deposition modeling, meniscus-confined electrodeposition, conformal printing on a rotating mandrel, UV-assisted and solvent-cast 3D printings) and their advantages and disadvantages regarding their utilization for the fabrication of helical microstructures are discussed. Focused ion beam chemical vapour deposition and microstereolithography techniques enable the fabrication of very precise shapes with a resolution down to ∼100 nm. However, these techniques may have material constraints (e.g., low viscosity) and/or may need special process conditions (e.g., vacuum chamber) and expensive equipment. The five other techniques based on robotic extrusion of materials through a nozzle are relatively cost-effective, however show lower resolution and less precise features. The popular fused deposition modeling method offers a wide variety of printable materials but the helical microstructures manufactured featured a less precise geometry compared to the other printing methods discussed in this review. The UV-assisted and the solvent-cast 3D printing methods both demonstrated high performance for the printing of 3D freeform structures such as the helix shape. However, the compatible materials used in these methods were limited to UV-curable polymers and polylactic acid (PLA), respectively. Meniscus-confined electrodeposition is a flexible, low cost technique that is capable of fabricating 3D structures both in nano- and microscales including freeform helical microstructures (down to few microns) under room conditions using metals. However, the metals suitable for this technique are limited to those that can be electrochemically deposited with the use of an electrolyte solution. The highest precision on the helix geometry was achieved using the conformal printing on a rotating mandrel. This method offers the lowest shape deformation after printing but requires more tools (e.g., mandrel, motor) and the printed structure must be separated from the mandrel. Helical microstructures made of multifunctional materials (e.g., carbon nanotube nanocomposites, metallic coated polymer template) were used in different technological applications such as strain/load sensors, cell separators and micro-antennas. These innovative 3D microsystems exploiting the unique helix shape demonstrated their potential for better performance and more compact microsystems.

Membrane separation of hydrocarbons

DOEpatents

Funk, Edward W.; Kulkarni, Sudhir S.; Chang, Y. Alice

1986-01-01

Mixtures of heavy oils and light hydrocarbons may be separated by passing the mixture over a polymeric membrane which comprises a polymer capable of maintaining its integrity in the presence of hydrocarbon compounds at temperature ranging from about ambient to about 100.degree. C. and pressures ranging from about 50 to about 1000 psi. The membranes which possess pore sizes ranging from about 10 to about 500 Angstroms are cast from a solvent solution and recovered.

CsPbBr 3 Solar Cells: Controlled Film Growth through Layer-by-Layer Quantum Dot Deposition

DOE PAGES

Hoffman, Jacob B.; Zaiats, Gary; Wappes, Isaac; ...

2017-10-25

All inorganic cesium lead bromide (CsPbBr 3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr 3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr 3 devices. Our layer-by-layer methodology, which makes use of CsPbBr 3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally,more » a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr 3 thickness produce champion devices that reach power conversion efficiencies of 5.5% with a V oc value of 1.4 V. Finally, the layered QD deposition demonstrates a controlled perovskite film architecture for developing efficient, high open-circuit photovoltaic devices.« less

Improvement of CO2/N2 separation performance by polymer matrix cellulose acetate butyrate

NASA Astrophysics Data System (ADS)

Lee, R. J.; Jawad, Z. A.; Ahmad, A. L.; Ngo, J. Q.; Chua, H. B.

2017-06-01

With the rapid development of modern civilization, carbon dioxide (CO2) is produced in large quantities and mainly generated from industrial sectors. The gas emission is the major contributor to global warming. To address this issue, the membrane technology is implemented for the CO2 removal, due to the energy efficiency and economic advantages presented. Cellulose acetate butyrate (CAB) is selected as the polymeric material, due to the excellent film-forming properties and capable of developing a defect-free layer of neat membrane. This study described the fabrication development of CAB using a wet phase inversion method with different casting conditions. Where the composition of the casting solutions (3-5 wt %) and solvent evaporation time (4-6 min) were determined. The outcomes of these dominant parameters were then used to determine the best CAB membrane for CO2/Nitrogen (N2) separation and supported by the characterization i.e. scanning electron micrograph. Gas permeation measurements showed satisfactory performance for CAB membrane fabricated with 5 min evaporation time and 4 wt% polymer composition (M2). Where, its permeance and selectivity are 120.19 GPU and 3.17, respectively. In summary, this study showed a brief outlined of the future direction and perspective of CAB membrane for CO2/N2 separation.

Prediction of Chemical Function: Model Development and ...

EPA Pesticide Factsheets

The United States Environmental Protection Agency’s Exposure Forecaster (ExpoCast) project is developing both statistical and mechanism-based computational models for predicting exposures to thousands of chemicals, including those in consumer products. The high-throughput (HT) screening-level exposures developed under ExpoCast can be combined with HT screening (HTS) bioactivity data for the risk-based prioritization of chemicals for further evaluation. The functional role (e.g. solvent, plasticizer, fragrance) that a chemical performs can drive both the types of products in which it is found and the concentration in which it is present and therefore impacting exposure potential. However, critical chemical use information (including functional role) is lacking for the majority of commercial chemicals for which exposure estimates are needed. A suite of machine-learning based models for classifying chemicals in terms of their likely functional roles in products based on structure were developed. This effort required collection, curation, and harmonization of publically-available data sources of chemical functional use information from government and industry bodies. Physicochemical and structure descriptor data were generated for chemicals with function data. Machine-learning classifier models for function were then built in a cross-validated manner from the descriptor/function data using the method of random forests. The models were applied to: 1) predict chemi

Honeycomb Films with Core-Shell Dispersed Phases Prepared by the Combination of Breath Figures and Phase Separation Process of Ternary Blends.

PubMed

Del Campo, A; de León, A S; Rodríguez-Hernández, J; Muñoz-Bonilla, A

2017-03-21

Herein, we propose a strategy to fabricate core-shell microstructures ordered in hexagonal arrays by combining the breath figures approach and phase separation of immiscible ternary blends. This simple strategy to fabricate these structures involves only the solvent casting of a ternary polymer blend under moist atmosphere, which provides a facile and low-cost fabrication method to obtain the porous structures with a core-shell morphology. For this purpose, blends consisting of polystyrene (PS) as a major component and PS 40 -b-P(PEGMA300) 48 amphiphilic copolymer and polydimethylsiloxane (PDMS) as minor components were dissolved in tetrahydrofuran and cast onto glass wafers under humid conditions, 70% of relative humidity. The resulting porous morphologies were characterized by optical and confocal Raman microscopy. In particular, confocal Raman results demonstrated the formation of core-shell morphologies into the ordered pores, in which the PS forms the continuous matrix, whereas the other two phases are located into the cavities (PDMS is the core while the amphiphilic copolymer is the shell). Besides, by controlling the weight ratio of the polymer blends, the structural parameters of the porous structure such as pore diameter and the size of the core can be effectively tuned.

CsPbBr 3 Solar Cells: Controlled Film Growth through Layer-by-Layer Quantum Dot Deposition

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

Hoffman, Jacob B.; Zaiats, Gary; Wappes, Isaac

All inorganic cesium lead bromide (CsPbBr 3) perovskite is a more stable alternative to methylammonium lead bromide (MAPbBr 3) for designing high open-circuit voltage solar cells and display devices. Poor solubility of CsBr in organic solvents makes typical solution deposition methods difficult to adapt for constructing CsPbBr 3 devices. Our layer-by-layer methodology, which makes use of CsPbBr 3 quantum dot (QD) deposition followed by annealing, provides a convenient way to cast stable films of desired thickness. The transformation from QDs into bulk during thermal annealing arises from the resumption of nanoparticle growth and not from sintering as generally assumed. Additionally,more » a large loss of organic material during the annealing process is mainly from 1-octadecene left during the QD synthesis. Utilizing this deposition approach for perovskite photovoltaics is examined using typical planar architecture devices. Devices optimized to both QD spin-casting concentration and overall CsPbBr 3 thickness produce champion devices that reach power conversion efficiencies of 5.5% with a V oc value of 1.4 V. Finally, the layered QD deposition demonstrates a controlled perovskite film architecture for developing efficient, high open-circuit photovoltaic devices.« less

Negatively charged polysulfone membranes with hydrophilicity and antifouling properties based on in situ cross-linked polymerization.

PubMed

Zhu, Lijing; Song, Haiming; Zhang, Dawei; Wang, Gang; Zeng, Zhixiang; Xue, Qunji

2017-07-15

Polysulfone (PSf) membrane has been widely used in water separation and purification, although, membrane fouling is still a serious problem limiting its potential. We aim to improve the antifouling of PSf membranes via a very simple and efficient method. In this work, antifouling PSf membranes were fabricated via in situ cross-linked polymerization coupled with non-solvent induced phase separation. In brief, acrylic acid (AA) and vinyltriethoxysilane (VTEOS) were copolymerized in PSf solution, then directly casted into membranes without purification. With the increase of monomers concentration, the morphology of the as-cast membranes changed from a finger-like morphology to a fully sponge-like structure due to the increased viscosity and decreased precipitation rate of the polymer solutions. Meanwhile, the hydrophilicity and electronegativity of modified membranes were highly improved leading to inhibited protein adsorption and improved antifouling property. Furthermore, in order to further find out the different roles player by AA and VTESO, the modified membrane without VTEOS was prepared and characterized. The results indicated that AA is more effective in the membrane hydrophilicity improvement, VTEOS is more crucial to improve membrane stability. This work provides valuable guidance for fabricating PSf membranes with hydrophilicity and antifouling property via in situ cross-linked polymerization. Copyright © 2017 Elsevier Inc. All rights reserved.

Pneumatic gap sensor and method

DOEpatents

Bagdal, Karl T.; King, Edward L.; Follstaedt, Donald W.

1992-01-01

An apparatus and method for monitoring and maintaining a predetermined width in the gap between a casting nozzle and a casting wheel, wherein the gap is monitored by means of at least one pneumatic gap sensor. The pneumatic gap sensor is mounted on the casting nozzle in proximity to the casting surface and is connected by means of a tube to a regulator and a transducer. The regulator provides a flow of gas through a restictor to the pneumatic gap sensor, and the transducer translates the changes in the gas pressure caused by the proximity of the casting wheel to the pneumatic gap sensor outlet into a signal intelligible to a control device. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. The apparatus and method enables accurate monitoring of the actual casting gap in a simple and reliable manner resistant to the extreme temperatures and otherwise hostile casting environment.

Pneumatic gap sensor and method

DOEpatents

Bagdal, K.T.; King, E.L.; Follstaedt, D.W.

1992-03-03

An apparatus and method for monitoring and maintaining a predetermined width in the gap between a casting nozzle and a casting wheel, wherein the gap is monitored by means of at least one pneumatic gap sensor. The pneumatic gap sensor is mounted on the casting nozzle in proximity to the casting surface and is connected by means of a tube to a regulator and a transducer. The regulator provides a flow of gas through a restictor to the pneumatic gap sensor, and the transducer translates the changes in the gas pressure caused by the proximity of the casting wheel to the pneumatic gap sensor outlet into a signal intelligible to a control device. The relative positions of the casting nozzle and casting wheel can thereby be selectively adjusted to continually maintain a predetermined distance between their adjacent surfaces. The apparatus and method enables accurate monitoring of the actual casting gap in a simple and reliable manner resistant to the extreme temperatures and otherwise hostile casting environment. 6 figs.

Methods and apparatuses for manufacturing monocrystalline cast silicon and monocrystalline cast silicon bodies for photovoltaics

DOEpatents

Stoddard, Nathan G [Gettysburg, PA

2011-11-01

Methods and apparatuses are provided for casting silicon for photovoltaic cells and other applications. With such methods and apparatuses, a cast body of monocrystalline silicon may be formed that is free of, or substantially free of, radially-distributed impurities and defects and having at least two dimensions that are each at least about 35 cm is provided.

A work study of the CAD/CAM method and conventional manual method in the fabrication of spinal orthoses for patients with adolescent idiopathic scoliosis.

PubMed

Wong, M S; Cheng, J C Y; Wong, M W; So, S F

2005-04-01

A study was conducted to compare the CAD/CAM method with the conventional manual method in fabrication of spinal orthoses for patients with adolescent idiopathic scoliosis. Ten subjects were recruited for this study. Efficiency analyses of the two methods were performed from cast filling/ digitization process to completion of cast/image rectification. The dimensional changes of the casts/ models rectified by the two cast rectification methods were also investigated. The results demonstrated that the CAD/CAM method was faster than the conventional manual method in the studied processes. The mean rectification time of the CAD/CAM method was shorter than that of the conventional manual method by 108.3 min (63.5%). This indicated that the CAD/CAM method took about 1/3 of the time of the conventional manual to finish cast rectification. In the comparison of cast/image dimensional differences between the conventional manual method and the CAD/CAM method, five major dimensions in each of the five rectified regions namely the axilla, thoracic, lumbar, abdominal and pelvic regions were involved. There were no significant dimensional differences (p < 0.05) in 19 out of the 25 studied dimensions. This study demonstrated that the CAD/CAM system could save the time in the rectification process and offer a relatively high resemblance in cast rectification as compared with the conventional manual method.

Accuracy of ringless casting and accelerated wax-elimination technique: a comparative in vitro study.

PubMed

Prasad, Rahul; Al-Keraif, Abdulaziz Abdullah; Kathuria, Nidhi; Gandhi, P V; Bhide, S V

2014-02-01

The purpose of this study was to determine whether the ringless casting and accelerated wax-elimination techniques can be combined to offer a cost-effective, clinically acceptable, and time-saving alternative for fabricating single unit castings in fixed prosthodontics. Sixty standardized wax copings were fabricated on a type IV stone replica of a stainless steel die. The wax patterns were divided into four groups. The first group was cast using the ringless investment technique and conventional wax-elimination method; the second group was cast using the ringless investment technique and accelerated wax-elimination method; the third group was cast using the conventional metal ring investment technique and conventional wax-elimination method; the fourth group was cast using the metal ring investment technique and accelerated wax-elimination method. The vertical marginal gap was measured at four sites per specimen, using a digital optical microscope at 100× magnification. The results were analyzed using two-way ANOVA to determine statistical significance. The vertical marginal gaps of castings fabricated using the ringless technique (76.98 ± 7.59 μm) were significantly less (p < 0.05) than those castings fabricated using the conventional metal ring technique (138.44 ± 28.59 μm); however, the vertical marginal gaps of the conventional (102.63 ± 36.12 μm) and accelerated wax-elimination (112.79 ± 38.34 μm) castings were not statistically significant (p > 0.05). The ringless investment technique can produce castings with higher accuracy and can be favorably combined with the accelerated wax-elimination method as a vital alternative to the time-consuming conventional technique of casting restorations in fixed prosthodontics. © 2013 by the American College of Prosthodontists.

Methods and apparatuses for manufacturing geometric multicrystalline cast silicon and geometric multicrystalline cast silicon bodies for photovoltaics

DOEpatents

Stoddard, Nathan G

2015-02-10

Methods and apparatuses are provided for casting silicon for photovoltaic cells and other applications. With such methods and apparatuses, a cast body of geometrically ordered multi-crystalline silicon may be formed that is free or substantially free of radially-distributed impurities and defects and having at least two dimensions that are each at least about 10 cm is provided.

Comparison of cast materials for the treatment of congenital idiopathic clubfoot using the Ponseti method: a prospective randomized controlled trial

PubMed Central

Hui, Catherine; Joughin, Elaine; Nettel-Aguirre, Alberto; Goldstein, Simon; Harder, James; Kiefer, Gerhard; Parsons, David; Brauer, Carmen; Howard, Jason

2014-01-01

Background The Ponseti method of congenital idiopathic clubfoot correction has traditionally specified plaster of Paris (POP) as the cast material of choice; however, there are negative aspects to using POP. We sought to determine the influence of cast material (POP v. semirigid fibreglass [SRF]) on clubfoot correction using the Ponseti method. Methods Patients were randomized to POP or SRF before undergoing the Ponseti method. The primary outcome measure was the number of casts required for clubfoot correction. Secondary outcome measures included the number of casts by severity, ease of cast removal, need for Achilles tenotomy, brace compliance, deformity relapse, need for repeat casting and need for ancillary surgical procedures. Results We enrolled 30 patients: 12 randomized to POP and 18 to SRF. There was no difference in the number of casts required for clubfoot correction between the groups (p = 0.13). According to parents, removal of POP was more difficult (p < 0.001), more time consuming (p < 0.001) and required more than 1 method (p < 0.001). At a final follow-up of 30.8 months, the mean times to deformity relapse requiring repeat casting, surgery or both were 18.7 and 16.4 months for the SRF and POP groups, respectively. Conclusion There was no significant difference in the number of casts required for correction of clubfoot between the 2 materials, but SRF resulted in a more favourable parental experience, which cannot be ignored as it may have a positive impact on psychological well-being despite the increased cost associated. PMID:25078929

Freeze-Casting of Porous Biomaterials: Structure, Properties and Opportunities

PubMed Central

Deville, Sylvain

2010-01-01

The freeze-casting of porous materials has received a great deal of attention during the past few years. This simple process, where a material suspension is simply frozen and then sublimated, provides materials with unique porous architectures, where the porosity is almost a direct replica of the frozen solvent crystals. This review focuses on the recent results on the process and the derived porous structures with regards to the biomaterials applications. Of particular interest is the architecture of the materials and the versatility of the process, which can be readily controlled and applied to biomaterials applications. A careful control of the starting formulation and processing conditions is required to control the integrity of the structure and resulting properties. Further in vitro and in vivo investigations are required to validate the potential of this new class of porous materials.

Development and evaluation of a sublingual film of the antiemetic granisetron hydrochloride.

PubMed

Kalia, Vani; Garg, Tarun; Rath, Gautam; Goyal, Amit Kumar

2016-05-01

The objective of this study was to develop an oral transmucosal formulation of an antiemetic drug that can not only serve in the active form but also provide a controlled release profile. In this study, sublingual films based on the biodegradable and water-soluble polymers, that is HPMCK-4M and PVPK-30, were developed by the solvent casting method, and were loaded with the antiemetic drug granisetron hydrochloride (granisetron HCl). The entrapment efficiency of the developed formulation was found to be 86%. The in vitro profile showed an instant release of the drug from the sublingual film, in a pattern following the first order kinetics array. The in vivo studies showed that granisetron HCl was delivered in its active state and showed effective results, as compared to its activity in the marketed formulation.

Silver Eco-Solvent Ink for Reactive Printing of Polychromatic SERS and SPR Substrates

PubMed Central

Dustov, Mavlavi; Goldt, Anastasia E.; Sukhorukova, Irina V.; Grünert, Wolfgang; Grigorieva, Anastasia V.

2018-01-01

A new reactive ink based on a silver citrate complex is proposed for a photochemical route to surface-enhanced Raman spectroscopy active substrates with controllable extinction spectra. The drop-cast test of the ink reveals homogeneous nucleation of silver and colloid particle growth originating directly from photochemical in situ reduction in droplets, while the following evaporation of the deposited ink produces small nano- and micron-size particles. The prepared nanostructures and substrates were accurately characterized by electron microscopy methods and optical extinction spectroscopy. Varying the duration of UV irradiation allows tuning the morphology of individual silver nanoparticles forming hierarchical ring structures with numerous “hot spots” for most efficient Raman enhancement. Raman measurements of probe molecules of rhodamine 6G and methylene blue reached the largest signal enhancement of 106 by the resonance effects. PMID:29425119

Silver Eco-Solvent Ink for Reactive Printing of Polychromatic SERS and SPR Substrates.

PubMed

Dustov, Mavlavi; Golovina, Diana I; Polyakov, Alexander Yu; Goldt, Anastasia E; Eliseev, Andrei A; Kolesnikov, Efim A; Sukhorukova, Irina V; Shtansky, Dmitry V; Grünert, Wolfgang; Grigorieva, Anastasia V

2018-02-09

A new reactive ink based on a silver citrate complex is proposed for a photochemical route to surface-enhanced Raman spectroscopy active substrates with controllable extinction spectra. The drop-cast test of the ink reveals homogeneous nucleation of silver and colloid particle growth originating directly from photochemical in situ reduction in droplets, while the following evaporation of the deposited ink produces small nano- and micron-size particles. The prepared nanostructures and substrates were accurately characterized by electron microscopy methods and optical extinction spectroscopy. Varying the duration of UV irradiation allows tuning the morphology of individual silver nanoparticles forming hierarchical ring structures with numerous "hot spots" for most efficient Raman enhancement. Raman measurements of probe molecules of rhodamine 6G and methylene blue reached the largest signal enhancement of 10⁶ by the resonance effects.

Dissofilm: A Novel Approach for Delivery of Phenobarbital; Design and Characterization

PubMed Central

Yellanki, SK; Jagtap, S; Masareddy, R

2011-01-01

An attempt to develop and evaluate mouth-dissolving film of phenobarbital for quick effect in treatment of epilepsy occurring in pediatric population has been made in the present study. Suitable film formers and plasticizers are selected based on optimization studies. Effect of superdisintegrants in formulation of mouth dissolving films at different concentrations has been investigated. Films were prepared by solvent casting method. The prepared films were evaluated for physicochemical parameters, in vitro disintegration and dissolution time, in vitro release rate study, stability study, and in vivo animal safety study. The best formulation was found to be F3 showing 96.57% drug release in 14 min, following first-order kinetics. X-Ray diffraction studies show change in crystalline nature of drug in formulation. In vivo studies in hamster reports effective and safe use of formulation in animals. PMID:21897656

'Fast cast' and 'needle Tenotomy' protocols with the Ponseti method to improve clubfoot management in Bangladesh.

PubMed

Evans, Angela; Chowdhury, Mamun; Rana, Sohel; Rahman, Shariar; Mahboob, Abu Hena

2017-01-01

The management of congenital talipes equino varus ( clubfoot deformity ) has been transformed in the last 20 years as surgical correction has been replaced by the non-surgical Ponseti method. The Ponseti method, consists of corrective serial casting followed by maintenance bracing, and has been repeatedly demonstrated to give best results - regarded as the 'gold standard' treatment for paediatric clubfoot. To develop the study protocol Level 2 evidence was used to modify the corrective casting phase of the Ponseti method in children aged up to 12 months. Using Level 4 evidence, the percutaneous Achilles tenotomy (PAT) was performed using a 19-gauge needle instead of a scalpel blade, a technique found to reduce bleeding and scarring. A total of 123 children participated in this study; 88 male, 35 female. Both feet were affected in 67 cases, left only in 22 cases, right only in 34 cases. Typical clubfeet were found in 112/123 cases, six atypical, five syndromic. The average age at first cast was 51 days (13-240 days).The average number of casts applied was five (2-10 casts). The average number of days between the first cast and brace was 37.8 days (10-122 days), including 21 days in a post-PAT cast. Hence, average time of corrective casts was 17 days.Parents preferred the reduced casting time, and were less concerned about unseen skin wounds.PAT was performed in 103/123 cases, using the needle technique. All post tenotomy casts were in situ for three weeks. Minor complications occurred in seven cases - four cases had skin lesions, three cases disrupted casting phase. At another site, 452 PAT were performed using the needle technique. The 'fast cast' protocol Ponseti casting was successfully used in infants aged less than 8 months. Extended manual manipulation of two minutes was the essential modification. Parents preferred the faster treatment phase, and ability to closer observe the foot and skin. The treating physiotherapists preferred the 'fast cast' protocol, achieving better correction with less complication. The needle technique for PAT is a further improvement for the Ponseti method.

Analysis of four dental alloys following torch/centrifugal and induction/ vacuum-pressure casting procedures.

PubMed

Thompson, Geoffrey A; Luo, Qing; Hefti, Arthur

2013-12-01

Previous studies have shown casting methodology to influence the as-cast properties of dental casting alloys. It is important to consider clinically important mechanical properties so that the influence of casting can be clarified. The purpose of this study was to evaluate how torch/centrifugal and inductively cast and vacuum-pressure casting machines may affect the castability, microhardness, chemical composition, and microstructure of 2 high noble, 1 noble, and 1 base metal dental casting alloys. Two commonly used methods for casting were selected for comparison: torch/centrifugal casting and inductively heated/ vacuum-pressure casting. One hundred and twenty castability patterns were fabricated and divided into 8 groups. Four groups were torch/centrifugally cast in Olympia (O), Jelenko O (JO), Genesis II (G), and Liberty (L) alloys. Similarly, 4 groups were cast in O, JO, G, and L by an inductively induction/vacuum-pressure casting machine. Each specimen was evaluated for casting completeness to determine a castability value, while porosity was determined by standard x-ray techniques. Each group was metallographically prepared for further evaluation that included chemical composition, Vickers microhardness, and grain analysis of microstructure. Two-way ANOVA was used to determine significant differences among the main effects. Statistically significant effects were examined further with the Tukey HSD procedure for multiple comparisons. Data obtained from the castability experiments were non-normal and the variances were unequal. They were analyzed statistically with the Kruskal-Wallis rank sum test. Significant results were further investigated statistically with the Steel-Dwass method for multiple comparisons (α=.05). The alloy type had a significant effect on surface microhardness (P<.001). In contrast, the technique used for casting did not affect the microhardness of the test specimen (P=.465). Similarly, the interaction between the alloy and casting technique was not significant (P=.119). A high level of castability (98.5% on average) was achieved overall. The frequency of casting failures as a function of alloy type and casting method was determined. Failure was defined as a castability index score of <100%. Three of 28 possible comparisons between alloy and casting combinations were statistically significant. The results suggested that casting technique affects the castability index of alloys. Radiographic analysis detected large porosities in regions near the edge of the castability pattern and infrequently adjacent to noncast segments. All castings acquired traces of elements found in the casting crucibles. The grain size for each dental casting alloy was generally finer for specimens produced by the induction/vacuum-pressure method. The difference was substantial for JO and L. This study demonstrated a relation between casting techniques and some physical properties of metal ceramic casting alloys. Copyright © 2013 Editorial Council for the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

[Comparative adaptation of crowns of selective laser melting and wax-lost-casting method].

PubMed

Li, Guo-qiang; Shen, Qing-yi; Gao, Jian-hua; Wu, Xue-ying; Chen, Li; Dai, Wen-an

2012-07-01

To investigate the marginal adaptation of crowns fabricated by selective laser melting (SLM) and wax-lost-casting method, so as to provide an experimental basis for clinic. Co-Cr alloy full crown were fabricated by SLM and wax-lost-casting for 24 samples in each group. All crowns were cemented with zinc phosphate cement and cut along longitudinal axis by line cutting machine. The gap between crown tissue surface and die was measured by 6-point measuring method with scanning electron microscope (SEM). The marginal adaptation of crowns fabricated by SLM and wax-lost-casting were compared statistically. The gap between SLM crowns were (36.51 ± 2.94), (49.36 ± 3.31), (56.48 ± 3.35), (42.20 ± 3.60) µm, and wax-lost-casting crowns were (68.86 ± 5.41), (58.86 ± 6.10), (70.62 ± 5.79), (69.90 ± 6.00) µm. There were significant difference between two groups (P < 0.05). Co-Cr alloy full crown fabricated by wax-lost-casting method and SLM method provide acceptable marginal adaptation in clinic, and the marginal adaptation of SLM is better than that of wax-lost-casting method.

Microporous Poly(L-Lactic Acid) Membranes Fabricated by Polyethylene Glycol Solvent-Cast/Particulate Leaching Technique

PubMed Central

Selvam, Shivaram; Chang, Wenji V.; Nakamura, Tamako; Samant, Deedar M.; Thomas, Padmaja B.; Trousdale, Melvin D.; Mircheff, Austin K.; Schechter, Joel E.

2009-01-01

With the eventual goal of developing a tissue-engineered tear secretory system, we found that primary lacrimal gland acinar cells grown on solid poly(L-lactic acid) (PLLA) supports expressed the best histiotypic morphology. However, to be able to perform vectorial transport functions, epithelia must be supported by a permeable substratum. In the present study, we describe the use of a solvent-cast/particulate leaching technique to fabricate microporous PLLA membranes (mpPLLAm) from PLLA/polyethylene glycol blends. Scanning electron microscopy revealed pores on both the air-cured (∼4 μm) and glass-cured sides (<2 μm) of the mpPLLAm. Diffusion studies were performed with mpPLLAm fabricated from 57.1% PLLA/42.9% polyethylene glycol blends to confirm the presence of channelized pores. The data reveal that glucose, L-tryptophan, and dextran (a high molecular weight glucose polymer) readily permeate mpPLLAm. Diffusion of the immunoglobulin G through the mpPLLAm decreased with time, suggesting the possible adsorption and occlusion of the pores. Cells cultured on the mpPLLAm (57.1/42.9 wt%) grew to subconfluent monolayers but retained histiotypic morphological and physiological characteristics of lacrimal acinar cells in vivo. Our results suggest that mpPLLAm fabricated using this technique may be useful as a scaffold for a bioartificial lacrimal gland device. PMID:19260769

Synthesis and characterization of magnetic of Ni/ABS nanocomposites by electrical explosion of wire in liquid and solution blending methods

NASA Astrophysics Data System (ADS)

Thuyet-Nguyen, Minh; Hai-Nguyen, Hong; Kim, Won Joo; Kim, Ho Yoon; Kim, Jin-Chun

2017-03-01

Nanomaterials have attracted great attention from chemists, physicists and materials scientists because of their application benefits and special properties. Thermoplastics have been used in many applications such as molding of non-electrical components, conducting, magnetic field and 3D printing. Nanocomposites are known as a material which blends the best properties of components, a high performance material exhibits unusual property combinations and unique design possibilities. In this research, we focused to investigate and report primary results in the synthesis of magnetic nanocomposites based on acrylonitrile butadiene styrene (ABS), which are useful and important thermoplastics. Nickel nanopowder was prepared by electrical explosion of wire in a liquid were used as magnetic component. The composites were prepared by following steps, first the obtained Ni nanopowders were incorporated into the ABS matrix via a solution blending method (drop-casting), and then the solvent was evaporated. The characterizations of obtaining composites were analyzed by field emission scanning electron microscopy, X-Ray Diffraction analysis and vibrating sample magnetometer.

Hands-Off and Hands-On Casting Consistency of Amputee below Knee Sockets Using Magnetic Resonance Imaging

PubMed Central

Rowe, Philip

2013-01-01

Residual limb shape capturing (Casting) consistency has a great influence on the quality of socket fit. Magnetic Resonance Imaging was used to establish a reliable reference grid for intercast and intracast shape and volume consistency of two common casting methods, Hands-off and Hands-on. Residual limbs were cast for twelve people with a unilateral below knee amputation and scanned twice for each casting concept. Subsequently, all four volume images of each amputee were semiautomatically segmented and registered to a common coordinate system using the tibia and then the shape and volume differences were calculated. The results show that both casting methods have intra cast volume consistency and there is no significant volume difference between the two methods. Inter- and intracast mean volume differences were not clinically significant based on the volume of one sock criteria. Neither the Hands-off nor the Hands-on method resulted in a consistent residual limb shape as the coefficient of variation of shape differences was high. The resultant shape of the residual limb in the Hands-off casting was variable but the differences were not clinically significant. For the Hands-on casting, shape differences were equal to the maximum acceptable limit for a poor socket fit. PMID:24348164

Hands-off and hands-on casting consistency of amputee below knee sockets using magnetic resonance imaging.

PubMed

Safari, Mohammad Reza; Rowe, Philip; McFadyen, Angus; Buis, Arjan

2013-01-01

Residual limb shape capturing (Casting) consistency has a great influence on the quality of socket fit. Magnetic Resonance Imaging was used to establish a reliable reference grid for intercast and intracast shape and volume consistency of two common casting methods, Hands-off and Hands-on. Residual limbs were cast for twelve people with a unilateral below knee amputation and scanned twice for each casting concept. Subsequently, all four volume images of each amputee were semiautomatically segmented and registered to a common coordinate system using the tibia and then the shape and volume differences were calculated. The results show that both casting methods have intra cast volume consistency and there is no significant volume difference between the two methods. Inter- and intracast mean volume differences were not clinically significant based on the volume of one sock criteria. Neither the Hands-off nor the Hands-on method resulted in a consistent residual limb shape as the coefficient of variation of shape differences was high. The resultant shape of the residual limb in the Hands-off casting was variable but the differences were not clinically significant. For the Hands-on casting, shape differences were equal to the maximum acceptable limit for a poor socket fit.

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)

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

2012-02-01

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.

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

DOEpatents

Johnson, Robert Alan; Schaeffer, Jon Conrad; Lee, Ching-Pang; Abuaf, Nesim; Hasz, Wayne Charles

2002-01-01

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.

New methods and materials for molding and casting ice formations

NASA Technical Reports Server (NTRS)

Reehorst, Andrew L.; Richter, G. Paul

1987-01-01

This study was designed to find improved materials and techniques for molding and casting natural or simulated ice shapes that could replace the wax and plaster method. By utilizing modern molding and casting materials and techniques, a new methodology was developed that provides excellent reproduction, low-temperature capability, and reasonable turnaround time. The resulting casts are accurate and tough.

Assessment of morphology, topography and chemical composition of water-repellent films based on polystyrene/titanium dioxide nanocomposites

NASA Astrophysics Data System (ADS)

Bolvardi, Beleta; Seyfi, Javad; Hejazi, Iman; Otadi, Maryam; Khonakdar, Hossein Ali; Drechsler, Astrid; Holzschuh, Matthias

2017-02-01

In this study, polystyrene (PS)/titanium dioxide (TiO2) films were fabricated through simple solution casting technique via a modified phase separation process. The presented approach resulted in a remarkable reduction in the required amount of nanoparticles for achieving superhydrophobicity. Scanning electron microscopy (SEM) and 3D confocal microscopy were utilized to characterize surface morphology and topography of samples, respectively. An attempt was made to give an in-depth analysis on the surface rough structure using 3D roughness profiles. It was found that high inclusions of non-solvent and nanoparticles resulted in a stable self-cleaning behavior due to the strong presence of hydrophobic TiO2 nanoparticles on the surface. Quite unexpectedly, low inclusions of nanoparticles and non-solvent also resulted in superhydrophobic property mainly due to the proper level of induced surface roughness. XPS analysis was also utilized to determine the chemical composition of the films' surfaces. The results of falling drop experiments showed that the sample containing a higher level of nanoparticles had a much lower mechanical resistance against the induced harsh conditions. All in all, the presented method has shown promising potential in fabrication of superhydrophobic surfaces with self-cleaning behavior using the lowest content of nanoparticles.

Preparation of laminated poly(ε-caprolactone)-gelatin-hydroxyapatite nanocomposite scaffold bioengineered via compound techniques for bone substitution

PubMed Central

Hamlekhan, Azhang; Moztarzadeh, Fathollah; Mozafari, Masoud; Azami, Mahmoud; Nezafati, Nader

2011-01-01

In this research, new bioactive nanocomposite scaffolds were successfully developed using poly(ε-caprolactone) (PCL), cross-linked gelatin and nanoparticles of hydroxyapatite (HAp) after testing different solvents and methods. First, HAp powder was synthesized via a chemical precipitation technique and characterized. Then, the nanocomposites were prepared through layer solvent casting combined with freeze-drying and lamination techniques. According to the results, the increasing of the PCL weight in the scaffolds led to the improvement of the mechanical properties. The amount of ultimate stress, stiffness and also elastic modulus increased from 8 MPa for 0% wt PCL to 23.5 MPa for 50% wt PCL. The biomineralization study revealed the formation of an apatite layer on the scaffolds after immersion in simulated body fluid (SBF). The Ca-P ratios were in accordance to nonstoichiometric biological apatite, which was approximately 1.67. The in vitro biocompatibility and cytocompatibility of the scaffolds were tested using mesenchymal stem cells (MSCs), and the results indicated no sign of toxicity, and cells were found to be attached to the scaffold walls. The in vivo biocompatibility and osteogenesis of these scaffolds in the animal experiments is also under investigation, and the result will be published at the end of the study. PMID:23507731

Transmutation Fuel Fabrication-Fiscal Year 2016

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

Fielding, Randall Sidney; Grover, Blair Kenneth

ABSTRACT Nearly all of the metallic fuel that has been irradiated and characterized by the Advanced Fuel Campaign, and its earlier predecessors, has been arc cast. Arc casting is a very flexible method of casting lab scale quantities of materials. Although the method offers flexibility, it is an operator dependent process. Small changes in parameter space or alloy composition may affect how the material is cast. This report provides a historical insight in how the casting process has been modified over the history of the advanced fuels campaign as well as the physical parameters of the fuels cast in fiscalmore » year 2016.« less

Rough case-based reasoning system for continues casting

NASA Astrophysics Data System (ADS)

Su, Wenbin; Lei, Zhufeng

2018-04-01

The continuous casting occupies a pivotal position in the iron and steel industry. The rough set theory and the CBR (case based reasoning, CBR) were combined in the research and implementation for the quality assurance of continuous casting billet to improve the efficiency and accuracy in determining the processing parameters. According to the continuous casting case, the object-oriented method was applied to express the continuous casting cases. The weights of the attributes were calculated by the algorithm which was based on the rough set theory and the retrieval mechanism for the continuous casting cases was designed. Some cases were adopted to test the retrieval mechanism, by analyzing the results, the law of the influence of the retrieval attributes on determining the processing parameters was revealed. A comprehensive evaluation model was established by using the attribute recognition theory. According to the features of the defects, different methods were adopted to describe the quality condition of the continuous casting billet. By using the system, the knowledge was not only inherited but also applied to adjust the processing parameters through the case based reasoning method as to assure the quality of the continuous casting and improve the intelligent level of the continuous casting.

Stainless steel porous substrates produced by tape casting

NASA Astrophysics Data System (ADS)

Mercadelli, Elisa; Gondolini, Angela; Pinasco, Paola; Sanson, Alessandra

2017-01-01

In this work the technological issues related to the production of tape cast large-area porous stainless steel supports for Solid Oxide Fuel Cells (SOFC) applications were carefully investigated. The slurry formulation was optimized in terms of amount and nature of the organic components needed: rice starch and polymethyl metacrylate were found to be, respectively, the most suitable pore former and binder because easily eliminated during the thermal treatment in reducing atmosphere. The compatibility of the binder system chosen with the most widely used solvents for screen printing inks was also evaluated. Finally the influence of the sintering temperature and of the refractory supports to be used during the thermal treatments onto the production of porous stainless steel supports was discussed. The whole process optimization allows to produce flat, crack-free metallic substrate 900-1000 μm thick, dimensions up to 5×5 cm and with a tailored porosity of 40% suitable for SOFCs application.

Magnetic Alignment of γ-Fe2O3 Nanoparticles in Polymer Nanocomposites

NASA Astrophysics Data System (ADS)

Jimenez, Andrew; Kumar, Sanat K.; Jestin, Jacques

Recent work in nanocomposites has been heavily focused on controlling the dispersion state of filler particles. The use of internal self-assembly based on matrix properties provides a limited solution to the desire for specified organizations. By introducing a magnetic field during the casting of a polymer solution it has been shown that particles can be oriented to form anisotropic structures - commonly sought after for improved mechanical properties. Here, magnetic nanoparticles were cast in two different polymer matrices to study the effect of various forces that lead to this highly desired alignment. The addition of the magnetic field as an external trigger was shown to not necessarily force the clustering, but rather orient the agglomerates already available in solution. This demonstrates the importance of other dominant forces introduced into the system by characteristics of the polymers themselves. While this magnetic field provides a direction for the sample, the key forces lie in the interactions between the polymers and nanoparticles (as well as their solvent). The study shows a dependence of anisotropy on the particle loading, matrix, and casting time, from which continued work hopes to quantify the clustering necessary to optimize alignment in the composite.

A Fundamental Approach to Adhesion: Synthesis, Surface Analysis, Thermodynamics and Mechanics.

DTIC Science & Technology

1978-02-01

Polyphenylquinoxaline LSS - Lap Shear Strength Pasa-Jell - Commercial acid etch (See p. 15 ) Turco - Commercial base etch (See p. 17 ) CTBN - Carboxyl-Terminated...solvent- cast films or powders. SEM/EDAX results were obtained from the fracture surfaces of lap-shear tested specimens. Epoxy and two epoxy/ CTBN bulk...A - - 24 CTBN 1300X8 (Goodrich carboxyl- 5 5 terminated butadiene-acrylonitrile) Piperidine 5 5 5 L9 III. RESULTS AND DISCUSS10N A. Titanium 6-4 (SEM

Predictive Model for the Meniscus-Guided Coating of High-Quality Organic Single-Crystalline Thin Films.

PubMed

Janneck, Robby; Vercesi, Federico; Heremans, Paul; Genoe, Jan; Rolin, Cedric

2016-09-01

A model that describes solvent evaporation dynamics in meniscus-guided coating techniques is developed. In combination with a single fitting parameter, it is shown that this formula can accurately predict a processing window for various coating conditions. Organic thin-film transistors (OTFTs), fabricated by a zone-casting setup, indeed show the best performance at the predicted coating speeds with mobilities reaching 7 cm 2 V -1 s -1 . © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Casting fine grained, fully dense, strong inorganic materials

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

Brown, Sam W.; Spencer, Larry S.; Phillips, Michael R.

2015-11-24

Methods and apparatuses for casting inorganic materials are provided. The inorganic materials include metals, metal alloys, metal hydrides and other materials. Thermal control zones may be established to control the propagation of a freeze front through the casting. Agitation from a mechanical blade or ultrasonic energy may be used to reduce porosity and shrinkage in the casting. After solidification of the casting, the casting apparatus may be used to anneal the cast part.

Influence of Solutocapillary Convection on Macrovoid Defect Formation in Polymeric Membranes

NASA Technical Reports Server (NTRS)

Pekny, M. R.; Zartman, J.; Greenberg, A. R.; Todd, P.; Krantz, W. B.

2001-01-01

Macrovoids (MVs) are large (10-50 micrometers) pores often found in polymeric membranes prepared via phase-inversion techniques. They are generally considered undesirable, as they adversely affect the permeability properties and performance of polymeric membranes for microfiltration, ultrafiltration, and reverse osmosis. However, MVs can be useful in certain thin-film applications in which vapor transmission is necessary, or for use as reservoirs for enzymes or liquid membrane material. If more could be learned about the nature and causes of MV formation, it might be possible to devise techniques to control and/or prevent MV formation that are more effective than those currently employed. Two hypotheses for the MV growth mechanism have been advanced. Reuvers proposed that once initiated, MV growth can be attributed to diffusion of (primarily) solvent to the MV nuclei. Because this mechanism does not involve gross movement of the MV, the presence or absence of body forces such as buoyancy should not significantly affect MV growth. On the other hand, Shojaie et al. proposed that solutocapillary convection induced by a steep surface-tension gradient along the MV/bulk solution interface enhances mass transfer to the growing MV. This interfacial convection exerts a force that pulls the growing MV downward into the casting solution. Both buoyancy and viscous drag hinder MV growth by inhibiting this motion. Thus, removing the buoyancy force by casting in microgravity should augment MV growth according to this hypothesis. Whereas neither surface tension nor gravity has a significant effect on MV growth according to the first hypothesis, buoyancy forces should be important if the second hypothesis is correct. The overall goal of this research is to test these two hypotheses in order to improve our understanding of the MV growth processing solvent-cast polymeric membranes. Studying MV growth in low-gravity conditions is pivotal to our ability to discriminate between these two hypotheses.

Casting evaluation of U-Zr alloy system fuel slug for SFR prepared by injection casting method

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

Song, Hoon; Kim, Jong-Hwan; Kim, Ki-Hwan

2013-07-01

Metal fuel slugs of U-Pu-Zr alloys for Sodium-cooled Fast Reactor (SFR) have conventionally been fabricated by a vacuum injection casting method. Recently, management of minor actinides (MA) became an important issue because direct disposal of the long-lived MA can be a long-term burden for a tentative repository up to several hundreds of thousand years. In order to recycle transuranic elements (TRU) retained in spent nuclear fuel, remote fabrication capability in a shielded hot cell should be prepared. Moreover, generation of long-lived radioactive wastes and loss of volatile species should be minimized during the recycled fuel fabrication step. In order tomore » prevent the evaporation of volatile elements such as Am, alternative fabrication methods of metal fuel slugs have been studied applying gravity casting, and improved injection casting in KAERI, including melting under inert atmosphere. And then, metal fuel slugs were examined with casting soundness, density, chemical analysis, particle size distribution and microstructural characteristics. Based on these results there is a high level of confidence that Am losses will also be effectively controlled by application of a modest amount of overpressure. A surrogate fuel slug was generally soundly cast by improved injection casting method, melted fuel material under inert atmosphere.« less

The influence of nanotexturing of poly(lactic-co-glycolic acid) films upon human ovarian cancer cell attachment

NASA Astrophysics Data System (ADS)

Yaşayan, Gökçen; Xue, Xuan; Collier, Pamela; Clarke, Philip; Alexander, Morgan R.; Marlow, Maria

2016-06-01

In this study, we have produced nanotextured poly(lactic-co-glycolic acid) (PLGA) films by using polystyrene (PS) particles as a template to make a polydimethylsiloxane mould against which PLGA is solvent cast. Biocompatible, biodegradable and nanotextured PLGA films were prepared with PS particles of diameter of 57, 99, 210, and 280 nm that produced domes of the same dimension in the PLGA surface. The effect of the particulate monolayer templating method was investigated to enable preparation of the films with uniformly ordered surface nanodomes. Cell attachment of a human ovarian cancer cell line (OVCAR3) alone and co-cultured with mesenchymal stem cells (MSCs) was evaluated on flat and topographically nano-patterned surfaces. Cell numbers were observed to increase on the nanotextured surfaces compared to non-textured surfaces both with OVCAR3 cultures and OVCAR3-MSC co-cultures at 24 and 48 h time points.

Tape method of forming a thin layer of doped lanthanum chromite particles and of bonding such on an electrode

DOEpatents

Richards, Von L.; Singhal, Subhash C.; Pal, Uday B.

1992-01-01

A combustible polymer film, useful for application of an interconnection on an electrode is made by: (1) providing doped LaCro.sub.3 particles; (2) dispersing doped LaCrO.sub.3 particles in a solvent, to provide a dispersion; (3) screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers; (4) admixing a fugitive polymer with the particles; (5) casting the dispersion to provide a film; (6) drying the film; and (7) stripping the film. The film can then be applied to a porous, preheated electrode top surface, and then electrochemical vapor depositing a dense skeletal LaCrO.sub.3 structure, between and around the doped LaCrO.sub.3 particles. Additional solid oxide electrolyte and fuel electrode layers can then be added to provide a fuel cell.

Tape method of forming a thin layer of doped lanthanum chromite particles and of bonding such on an electrode

DOEpatents

Richards, V.L.; Singhal, S.C.; Pal, U.B.

1992-07-21

A combustible polymer film, useful for application of an interconnection on an electrode is made by: (1) providing doped LaCro[sub 3] particles; (2) dispersing doped LaCrO[sub 3] particles in a solvent, to provide a dispersion; (3) screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers; (4) admixing a fugitive polymer with the particles; (5) casting the dispersion to provide a film; (6) drying the film; and (7) stripping the film. The film can then be applied to a porous, preheated electrode top surface, and then a dense skeletal LaCrO[sub 3] structure is electrochemically vapor deposited between and around the doped LaCrO[sub 3] particles. Additional solid oxide electrolyte and fuel electrode layers can then be added to provide a fuel cell. 4 figs.

Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH{sub 4}SCN

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

Premalatha, M.; Materials Research Center, Coimbatore-641 045; Mathavan, T., E-mail: tjmathavan@gmail.com, E-mail: kingslin.genova20@gmail.com

2016-05-23

Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10{sup −3} S cm{sup −1} for 20 mol % NH{sub 4}SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasingmore » temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.« less

Nanofibrillated Cellulose and Copper Nanoparticles Embedded in Polyvinyl Alcohol Films for Antimicrobial Applications

PubMed Central

Zhong, Tuhua; Oporto, Gloria S.; Jaczynski, Jacek; Jiang, Changle

2015-01-01

Our long-term goal is to develop a hybrid cellulose-copper nanoparticle material as a functional nanofiller to be incorporated in thermoplastic resins for efficiently improving their antimicrobial properties. In this study, copper nanoparticles were first synthesized through chemical reduction of cupric ions on TEMPO nanofibrillated cellulose (TNFC) template using borohydride as a copper reducing agent. The resulting hybrid material was embedded into a polyvinyl alcohol (PVA) matrix using a solvent casting method. The morphology of TNFC-copper nanoparticles was analyzed by transmission electron microscopy (TEM); spherical copper nanoparticles with average size of 9.2 ± 2.0 nm were determined. Thermogravimetric analysis and antimicrobial performance of the films were evaluated. Slight variations in thermal properties between the nanocomposite films and PVA resin were observed. Antimicrobial analysis demonstrated that one-week exposure of nonpathogenic Escherichia coli DH5α to the nanocomposite films results in up to 5-log microbial reduction. PMID:26137482

Polymer Ni-MH battery based on PEO-PVA-KOH polymer electrolyte

NASA Astrophysics Data System (ADS)

Yang, Chun-Chen

An alkaline polymer electrolyte film has been prepared by a solvent-casting method. Poly(vinyl alcohol), PVA is added to improve the ionic conductivity of the electrolyte. The ionic conductivity increases from 10 -7 to 10 -2 S cm -1 at room temperature when the weight percent ratio of poly(ethylene oxide), PEO to PVA is increased from 10:0 to 5:5. The activation energy of the ionic conductivity for the PEO-PVA-KOH polymer electrolyte is 3-8 kJ mol -1. The properties of the electrolyte film are characterized by a wide variety of techniques and it is found that the film exhibits good mechanical stability and high ionic conductivity at room temperature. The application of such electrolyte films to nickel-metal-hydride (Ni-MH) batteries is examined and the electrochemical characteristics of a polymer Ni-MH battery are obtained.

Mixing of immiscible polymers using nanoporous coordination templates

NASA Astrophysics Data System (ADS)

Uemura, Takashi; Kaseda, Tetsuya; Sasaki, Yotaro; Inukai, Munehiro; Toriyama, Takaaki; Takahara, Atsushi; Jinnai, Hiroshi; Kitagawa, Susumu

2015-07-01

The establishment of methodologies for the mixing of immiscible substances is highly desirable to facilitate the development of fundamental science and materials technology. Herein we describe a new protocol for the compatibilization of immiscible polymers at the molecular level using porous coordination polymers (PCPs) as removable templates. In this process, the typical immiscible polymer pair of polystyrene (PSt) and poly(methyl methacrylate) (PMMA) was prepared via the successive homopolymerizations of their monomers in a PCP to distribute the polymers inside the PCP particles. Subsequent dissolution of the PCP frameworks in a chelator solution affords a PSt/PMMA blend that is homogeneous in the range of several nanometers. Due to the unusual compatibilization, the thermal properties of the polymer blend are remarkably improved compared with the conventional solvent-cast blend. This method is also applicable to the compatibilization of PSt and polyacrylonitrile, which have very different solubility parameters.

Preparation and evaluation of polyurethane/cellulose nanowhisker bimodal foam nanocomposites for osteogenic differentiation of hMSCs.

PubMed

Shahrousvand, Ehsan; Shahrousvand, Mohsen; Ghollasi, Marzieh; Seyedjafari, Ehsan; Jouibari, Iman Sahebi; Babaei, Amir; Salimi, Ali

2017-09-01

Biocompatible and biodegradable polyurethanes (PUs) based on polycaprolactone diol (PCL) were prepared and filled with cellulose nanowhiskers (CNWs) obtained from wastepaper. The incorporated polyurethane nanocomposites were used to prepare foamed scaffolds with bimodal cell sizes through solvent casting/particulate leaching method. Sodium chloride and sugar porogens were also prepared to fabricate the scaffolds. The mechanical and thermal properties of PU/CNW nanocomposites were investigated. Incorporation of different CNWs resulted in various structures with tunable mechanical properties and biodegradability. All bimodal foam nanocomposites were biodegradable and also non-cytotoxic as revealed by MTT assay using SNL fibroblast cell line. PU/CNW foam scaffolds were used for osteogenic differentiation of human mesenchymal stem cells (hMSCs). Based on the results, such PU/CNW nanocomposites could support proliferation and osteogenic differentiation of hMSCs in three-dimensional synthetic extracellular matrix (ECM). Copyright © 2017 Elsevier Ltd. All rights reserved.

Physical and Clinical Evaluation of Hip Spica Cast applied with Three-slab Technique using Fibreglass Material

PubMed Central

Bitar, KM; Ferdhany, ME; Saw, A

2016-01-01

Introduction: Hip spica casting is an important component of treatment for developmental dysplasia of the hip (DDH) and popular treatment method for femur fractures in children. Breakage at the hip region is a relatively common problem of this cast. We have developed a three-slab technique of hip spica application using fibreglass as the cast material. The purpose of this review was to evaluate the physical durability of the spica cast and skin complications with its use. Methodology: A retrospective review of children with various conditions requiring hip spica immobilisation which was applied using our method. Study duration was from 1st of January 2014 until 31st December 2015. Our main outcomes were cast breakage and skin complications. For children with hip instability, the first cast would be changed after one month, and the second cast about two months later. Results: Twenty-one children were included, with an average age of 2.2 years. The most common indication for spica immobilisation was developmental dysplasia of the hip. One child had skin irritation after spica application. No spica breakage was noted. Conclusion: This study showed that the three-slab method of hip spica cast application using fibreglass material was durable and safe with low risk of skin complications. PMID:28553442

Method and mold for casting thin metal objects

DOEpatents

Pehrson, Brandon P; Moore, Alan F

2014-04-29

Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.

Method for casting thin metal objects

DOEpatents

Pehrson, Brandon P; Moore, Alan F

2015-04-14

Provided herein are various embodiments of systems for casting thin metal plates and sheets. Typical embodiments include layers of mold cavities that are oriented vertically for casting the metal plates. In some embodiments, the mold cavities include a beveled edge such that the plates that are cast have a beveled edge. In some embodiments, the mold cavities are filled with a molten metal through an open horizontal edge of the cavity. In some embodiments, the mold cavities are filled through one or more vertical feed orifices. Further disclosed are methods for forming a thin cast metal plate or sheet where the thickness of the cast part is in a range from 0.005 inches to 0.2 inches, and the surface area of the cast part is in a range from 16 square inches to 144 square inches.

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

Souza, Douglas F., E-mail: souzadf@outlook.com; Nunes, Eduardo H.M., E-mail: eduardohmn@gmail.com; Pimenta, Daiana S.

In this work we fabricated alumina samples by the freeze-casting technique using tert-butanol as the solvent. The prepared materials were examined by scanning electron microscopy and X-ray microtomography. Next, they were coated with sol–gel silica films by dip-coating. Permeability tests were carried out in order to assess the permeation behavior of the materials processed in this study. We observed that the sintering time and alumina loading showed a remarkable effect on both the structural properties and flexural strength of the freeze-cast samples. Nitrogen adsorption tests revealed that the silica prepared in this study exhibited a microporous structure. It was observedmore » that the presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance by about one order of magnitude. Because of the similar kinetic diameters of nitrogen and carbon dioxide, the CO{sub 2}/N{sub 2} system showed a separation efficiency that was lower than that observed for the He/CO{sub 2} and He/N{sub 2} systems. We noticed that increasing the feed pressure improved the separation capacity of the obtained materials. - Highlights: • Porous alumina samples obtained by the freeze-casting technique • Microporous silica coating prepared by a simple sol–gel dip-coating methodology • Samples examined by SEM, μ-CT, and nitrogen sorption tests • Mechanical tests were carried out in the freeze-cast samples. • The presence of silica coatings on the alumina surface decreased the CO{sub 2} permeance.« less

Automated Solvent Seaming of Large Polyimide Membranes

NASA Technical Reports Server (NTRS)

Rood, Robert; Moore, James D.; Talley, Chris; Gierow, Paul A.

2006-01-01

A solvent-based welding process enables the joining of precise, cast polyimide membranes at their edges to form larger precise membranes. The process creates a homogeneous, optical-quality seam between abutting membranes, with no overlap and with only a very localized area of figure disturbance. The seam retains 90 percent of the strength of the parent material. The process was developed for original use in the fabrication of wide-aperture membrane optics, with areal densities of less than 1 kg/m2, for lightweight telescopes, solar concentrators, antennas, and the like to be deployed in outer space. The process is just as well applicable to the fabrication of large precise polyimide membranes for flat or inflatable solar concentrators and antenna reflectors for terrestrial applications. The process is applicable to cast membranes made of CP1 (or equivalent) polyimide. The process begins with the precise fitting together and fixturing of two membrane segments. The seam is formed by applying a metered amount of a doped solution of the same polyimide along the abutting edges of the membrane segments. After the solution has been applied, the fixtured films are allowed to dry and are then cured by convective heating. The weld material is the same as the parent material, so that what is formed is a homogeneous, strong joint that is almost indistinguishable from the parent material. The success of the process is highly dependent on formulation of the seaming solution from the correct proportion of the polyimide in a suitable solvent. In addition, the formation of reliable seams depends on the deposition of a precise amount of the seaming solution along the seam line. To ensure the required precision, deposition is performed by use of an automated apparatus comprising a modified commercially available, large-format, ink-jet print head on an automated positioning table. The printing head jets the seaming solution into the seam area at a rate controlled in coordination with the movement of the positioning table.

Estimation of Heat Transfer Coefficient in Squeeze Casting of Magnesium Alloy AM60 by Experimental Polynomial Extrapolation Method

NASA Astrophysics Data System (ADS)

Sun, Zhizhong; Niu, Xiaoping; Hu, Henry

In this work, a different wall-thickness 5-step (with thicknesses as 3, 5, 8, 12, 20 mm) casting mold was designed, and squeeze casting of magnesium alloy AM60 was performed in a hydraulic press. The casting-die interfacial heat transfer coefficients (IHTC) in 5-step casting were determined based on experimental thermal histories data throughout the die and inside the casting which were recorded by fine type-K thermocouples. With measured temperatures, heat flux and IHTC were evaluated using the polynomial curve fitting method. The results show that the wall thickness affects IHTC peak values significantly. The IHTC value for the thick step is higher than that for the thin steps.

The Design of 3D-Printed Lattice-Reinforced Thickness-Varying Shell Molds for Castings.

PubMed

Shangguan, Haolong; Kang, Jinwu; Yi, Jihao; Zhang, Xiaochuan; Wang, Xiang; Wang, Haibin; Huang, Tao

2018-03-30

3D printing technologies have been used gradually for the fabrication of sand molds and cores for castings, even though these molds and cores are dense structures. In this paper, a generation method for lattice-reinforced thickness-varying shell molds is proposed and presented. The first step is the discretization of the STL (Stereo Lithography) model of a casting into finite difference meshes. After this, a shell is formed by surrounding the casting with varying thickness, which is roughly proportional to the surface temperature distribution of the casting that is acquired by virtually cooling it in the environment. A regular lattice is subsequently constructed to support the shell. The outside surface of the shell and lattice in the cubic mesh format is then converted to STL format to serve as the external surface of the new shell mold. The internal surface of the new mold is the casting's surface with the normals of all of the triangles in STL format reversed. Experimental verification was performed on an Al alloy wheel hub casting. Its lattice-reinforced thickness-varying shell mold was generated by the proposed method and fabricated by the binder jetting 3D printing. The poured wheel hub casting was sound and of good surface smoothness. The cooling rate of the wheel hub casting was greatly increased due to the shell mold structure. This lattice-reinforced thickness-varying shell mold generation method is of great significance for mold design for castings to achieve cooling control.

Thermally Cross-Linked Anion Exchange Membranes from Solvent Processable Isoprene Containing Ionomers

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

Tsai, Tsung-Han; Ertem, S. Piril; Maes, Ashley M.

2015-01-28

Random copolymers of isoprene and 4-vinylbenzyl chloride (VBCl) with varying compositions were synthesized via nitroxide-mediated polymerization. Subsequent quaternization afforded solvent processable and cross-linkable ionomers with a wide range of ion exchange capacities (IECs). Solution cast membranes were thermally cross-linked to form anion exchange membranes. Cross-linking was achieved by taking advantage of the unsaturations on the polyisoprene backbone, without added cross-linkers. A strong correlation was found between water uptake and ion conductivity of the membranes: conductivities of the membranes with IECs beyond a critical value were found to be constant related to their high water absorption. Environmentally controlled small-angle X-ray scatteringmore » experiments revealed a correlation between the average distance between ionic clusters and the ion conductivity, indicating that a well-connected network of ion clusters is necessary for efficient ion conduction and high ion conductivity.« less

Comparison of extraction methods for quantifying vitamin E from animal tissues.

PubMed

Xu, Zhimin

2008-12-01

Four extraction methods: (1) solvent (SOL), (2) ultrasound assisted solvent (UA), (3) saponification and solvent (SP), and (4) saponification and ultrasound assisted solvent (SP-UA), were used in sample preparation for quantifying vitamin E (tocopherols) in chicken liver and plasma samples. The extraction yields of SOL, UA, SP, and SP-UA methods obtained by adding delta-tocopherol as internal reference were 95%, 104%, 65%, and 62% for liver and 98%, 103%, 97%, and 94% for plasma, respectively. The methods with saponification significantly affected the stabilities of tocopherols in liver samples. The measured values of alpha- and gamma-tocopherols using the solvent only extraction (SOL) method were much lower than that using any of the other extraction methods. This indicated that less of the tocopherols in those samples were in a form that could be extracted directly by solvent. The measured value of alpha-tocopherol in the liver sample using the ultrasound assisted solvent (UA) method was 1.5-2.5 times of that obtained from the saponification and solvent (SP) method. The differences in measured values of tocopherols in the plasma samples by using the two methods were not significant. However, the measured value of the saponification and ultrasound assisted solvent (SP-UA) method was lower than either the saponification and solvent (SP) or the ultrasound assisted solvent (UA) method. Also, the reproducibility of the ultrasound assisted solvent (UA) method was greater than any of the saponification methods. Compared with the traditional saponification method, the ultrasound assisted solvent method could effectively extract tocopherols from sample matrix without any chemical degradation reactions, especially for complex animal tissue such as liver.

Method of casting articles of a bulk-solidifying amorphous alloy

DOEpatents

Lin, X.; Johnson, W.L.; Peker, A.

1998-08-25

A casting charge of a bulk-solidifying amorphous alloy is cast into a mold from a temperature greater than its crystallized melting temperature, and permitted to solidify to form an article. The oxygen content of the casting charge is limited to an operable level, as excessively high oxygen contents produce premature crystallization during the casting operation. During melting, the casting charge is preferably heated to a temperature above a threshold temperature to eliminate heterogeneous crystallization nucleation sites within the casting charge. The casting charge may be cast from above the threshold temperature, or it may be cooled to the casting temperature of more than the crystallized melting point but not more than the threshold temperature, optionally held at this temperature for a period of time, and thereafter cast. 8 figs.

Method of casting articles of a bulk-solidifying amorphous alloy

DOEpatents

Lin, Xianghong; Johnson, William L.; Peker, Atakan

1998-01-01

A casting charge of a bulk-solidifying amorphous alloy is cast into a mold from a temperature greater than its crystallized melting temperature, and permitted to solidify to form an article. The oxygen content of the casting charge is limited to an operable level, as excessively high oxygen contents produce premature crystallization during the casting operation. During melting, the casting charge is preferably heated to a temperature above a threshold temperature to eliminate heterogeneous crystallization nucleation sites within the casting charge. The casting charge may be cast from above the threshold temperature, or it may be cooled to the casting temperature of more than the crystallized melting point but not more than the threshold temperature, optionally held at this temperature for a period of time, and thereafter cast.

Gas anti-solvent precipitation assisted salt leaching for generation of micro- and nano-porous wall in bio-polymeric 3D scaffolds.

PubMed

Flaibani, Marina; Elvassore, Nicola

2012-08-01

The mass transport through biocompatible and biodegradable polymeric 3D porous scaffolds may be depleted by non-porous impermeable internal walls. As consequence the concentration of metabolites and growth factors within the scaffold may be heterogeneous leading to different cell fate depending on spatial cell location, and in some cases it may compromise cell survival. In this work, we fabricated polymeric scaffolds with micro- and nano-scale porosity by developing a new technique that couples two conventional scaffold production methods: solvent casting-salt leaching and gas antisolvent precipitation. 10-15 w/w solutions of a hyaluronic benzyl esters (HYAFF11) and poly-(lactic acid) (PLA) were used to fill packed beds of 0.177-0.425 mm NaCl crystals. The polymer precipitation in micro and nano-porous structures between the salt crystals was induced by high-pressure gas, then its flushing extracted the residual solvent. The salt was removed by water-wash. Morphological analysis by scanning electron microscopy showed a uniform porosity (~70%) and a high interconnectivity between porous. The polymeric walls were porous themselves counting for 30% of the total porosity. This wall porosity did not lead to a remarkable change in compressive modulus, deformation, and rupture pressure. Scaffold biocompatibility was tested with murine muscle cell line C2C12 for 4 and 7 days. Viability analysis and histology showed that micro- and nano-porous scaffolds are biocompatible and suitable for 3D cell culture promoting cell adhesion on the polymeric wall and allowing their proliferation in layers. Micro- and nano-scale porosities enhance cell migration and growth in the inner part of the scaffold. Copyright © 2012 Elsevier B.V. All rights reserved.

Comparing maximum intercuspal contacts of virtual dental patients and mounted dental casts.

PubMed

Delong, Ralph; Ko, Ching-Chang; Anderson, Gary C; Hodges, James S; Douglas, W H

2002-12-01

Quantitative measures of occlusal contacts are of paramount importance in the study of chewing dysfunction. A tool is needed to identify and quantify occlusal parameters without occlusal interference caused by the technique of analysis. This laboratory simulation study compared occlusal contacts constructed from 3-dimensional images of dental casts and interocclusal records with contacts found by use of conventional methods. Dental casts of 10 completely dentate adults were mounted in a semi-adjustable Denar articulator. Maximum intercuspal contacts were marked on the casts using red film. Intercuspal records made with an experimental vinyl polysiloxane impression material recorded maximum intercuspation. Three-dimensional virtual models of the casts and interocclusal records were made using custom software and an optical scanner. Contacts were calculated between virtual casts aligned manually (CM), aligned with interocclusal records scanned seated on the mandibular casts (C1) or scanned independently (C2), and directly from virtual interocclusal records (IR). Sensitivity and specificity calculations used the marked contacts as the standard. Contact parameters were compared between method pairs. Statistical comparisons used analysis of variance and the Tukey-Kramer post hoc test (P=<.05). Sensitivities (range 0.76-0.89) did not differ significantly among the 4 methods (P=.14); however, specificities (range 0.89-0.98) were significantly lower for IR (P=.0001). Contact parameters of methods CM, C1, and C2 differed significantly from those of method IR (P<.02). The ranking based on method pair comparisons was C2/C1 > CM/C1 = CM/C2 > C2/IR > CM/IR > C1/IR, where ">" means "closer than." Within the limits of this study, occlusal contacts calculated from aligned virtual casts accurately reproduce articulator contacts.

Simulation of the Continuous Casting and Cooling Behavior of Metallic Glasses

PubMed Central

Pei, Zhipu; Ju, Dongying

2017-01-01

The development of melt spinning technique for preparation of metallic glasses was summarized. The limitations as well as restrictions of the melt spinning embodiments were also analyzed. As an improvement and variation of the melt spinning method, the vertical-type twin-roll casting (VTRC) process was discussed. As the thermal history experienced by the casting metals to a great extent determines the qualities of final products, cooling rate in the quenching process is believed to have a significant effect on glass formation. In order to estimate the ability to produce metallic glasses by VTRC method, temperature and flow phenomena of the melt in molten pool were computed, and cooling rates under different casting conditions were calculated with the simulation results. Considering the fluid character during casting process, the material derivative method based on continuum theory was adopted in the cooling rate calculation. Results show that the VTRC process has a good ability in continuous casting metallic glassy ribbons. PMID:28772779

Simulation of the Continuous Casting and Cooling Behavior of Metallic Glasses.

PubMed

Pei, Zhipu; Ju, Dongying

2017-04-17

The development of melt spinning technique for preparation of metallic glasses was summarized. The limitations as well as restrictions of the melt spinning embodiments were also analyzed. As an improvement and variation of the melt spinning method, the vertical-type twin-roll casting (VTRC) process was discussed. As the thermal history experienced by the casting metals to a great extent determines the qualities of final products, cooling rate in the quenching process is believed to have a significant effect on glass formation. In order to estimate the ability to produce metallic glasses by VTRC method, temperature and flow phenomena of the melt in molten pool were computed, and cooling rates under different casting conditions were calculated with the simulation results. Considering the fluid character during casting process, the material derivative method based on continuum theory was adopted in the cooling rate calculation. Results show that the VTRC process has a good ability in continuous casting metallic glassy ribbons.

Surface biofunctionalization of three-dimensional porous poly(lactic acid) scaffold using chitosan/OGP coating for bone tissue engineering.

PubMed

Zeng, Sen; Ye, Jianhua; Cui, Zhixiang; Si, Junhui; Wang, Qianting; Wang, Xiaofeng; Peng, Kaiping; Chen, Wenzhe

2017-08-01

As one of the stimulators on bone formation, osteogenic growth peptide (OGP) improves both proliferation and differentiation of the bone cells in vitro and in vivo. The aim of this work was the preparation of three dimensional porous poly(lactic acid) (PLA) scaffold with high porosity from PLA-dioxane-water ternary system with the use of vacuum-assisted solvent casting, phase separation, solvent extraction and particle leaching methods. Then, by surface coating of PLA scaffold with chitosan (CS)/OGP solution, biofunctionalization of PLA scaffold had been completed for application in bone regeneration. The effects of frozen temperature (-20, -50, -80°C) and PLA solution concentration (10, 12, 14wt%) on the microstructure, water absorption, porosity, hydrophilicity, mechanical properties, and biocompatibility of PLA and CS/OGP/PLA scaffold were investigated. Results showed that both PLA and CS/OGP/PLA scaffolds have an interconnected network structure and a porosity of up to 96.1% and 91.5%, respectively. The CS/OGP/PLA scaffold exhibited better hydrophilicity and mechanical properties than that of uncoated PLA scaffold. Moreover, the results of cell culture test showed that CS/OGP coating could stimulate the proliferation and growth of osteoblast cells on CS/OGP/PLA scaffold. These finding suggested that the surface biofunctionalization by CS/OGP coating layer could be an effective method on enhancing cell adhesion to synthetic polymer-based scaffolds in tissue engineering application and the developed porous CS/OGP/PLA scaffold should be considered as alternative biomaterials for bone regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

Controlling morphology and chain aggregation in semiconducting conjugated polymers: the role of solvent on optical gain in MEH-PPV.

PubMed

Lampert, Zach E; Reynolds, C Lewis; Papanikolas, John M; Aboelfotoh, M Osama

2012-10-25

We report the results of a detailed investigation that addresses the influence of polymer morphology and chain aggregation, as controlled by the chemical nature of the solvent, on the optical gain properties of the conjugated polymer poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV). Using the variable stripe length technique in the picosecond regime, we have extensively studied the optical gain performance of asymmetric planar waveguides formed with thin MEH-PPV films spin-cast from concentrated chlorobenzene (CB) and tetrahydrofuran (THF) solutions onto thermally oxidized silicon substrates. CB and THF solvents were chosen based on their known ability to promote and effectively limit aggregate formation, respectively. Very large net gain coefficients are demonstrated, reaching values of 330 and 365 cm(-1), respectively, when optically pumping the waveguides with a maximum energy density of 85 μJ/cm(2). Our results clearly demonstrate that polymer morphology, and hence, the chain conformation dependence of the degree of aggregation in the films as controlled by the solvent, has minimal impact on the net gain. Moreover, the waveguides exhibit low loss coefficients of 10-20 cm(-1) at the ASE wavelength. These results question the importance of polymer morphology and aggregate formation in polymer-based optical devices operating at high excitation densities in the stimulated emission regime as would be characteristic of lasers and optical amplifiers.

A New Method to Grow SiC: Solvent-Laser Heated Floating Zone

NASA Technical Reports Server (NTRS)

Woodworth, Andrew A.; Neudeck, Philip G.; Sayir, Ali

2012-01-01

The solvent-laser heated floating zone (solvent-LHFZ) growth method is being developed to grow long single crystal SiC fibers. The technique combines the single crystal fiber growth ability of laser heated floating zone with solvent based growth techniques (e.g. traveling solvent method) ability to grow SiC from the liquid phase. Initial investigations reported in this paper show that the solvent-LHFZ method readily grows single crystal SiC (retains polytype and orientation), but has a significant amount of inhomogeneous strain and solvent rich inclusions.

Top-down approach for nanophase reconstruction in bulk heterojunction solar cells.

PubMed

Kong, Jaemin; Hwang, In-Wook; Lee, Kwanghee

2014-09-01

"Top-Down" nanophase reconstruction via a post-additive soaking process is first presented with various BHJ binary composites. By simply rinsing as-cast BHJ films with a solvent mixture containing a few traces of a nanophase-control reagent such as 1,8-diiodooctane, oversized fullerene-rich clusters (>100 nm in dia-meter) in the BHJ film are instataneously disassembled and entirely reorganized into finely intermixed donor/acceptor nanophases (ca. 10 nm) with a 3D compositional homogeneity, without surface segregation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Gas separation membranes

DOEpatents

Schell, William J.

1979-01-01

A dry, fabric supported, polymeric gas separation membrane, such as cellulose acetate, is prepared by casting a solution of the polymer onto a shrinkable fabric preferably formed of synthetic polymers such as polyester or polyamide filaments before washing, stretching or calendering (so called griege goods). The supported membrane is then subjected to gelling, annealing, and drying by solvent exchange. During the processing steps, both the fabric support and the membrane shrink a preselected, controlled amount which prevents curling, wrinkling or cracking of the membrane in flat form or when spirally wound into a gas separation element.

Organic fluid permeation through fluoropolymer membranes

DOEpatents

Nemser, Stuart M.; Kosaraju, Praveen; Bowser, John

2015-07-14

Separation of the components of liquid mixtures is achieved by contacting a liquid mixture with a nonporous membrane having a fluoropolymer selectively permeable layer and imposing a pressure gradient across the membrane from feed side to permeate side. Unusually high transmembrane flux is obtained when the membrane is subjected to one or more process conditions prior to separation. These include (a) leaving some residual amount of membrane casting solvent in the membrane, and (b) contacting the membrane with a component of the mixture to be separated for a duration effective to saturate the membrane with the component.

Methods for manufacturing geometric multi-crystalline cast materials

DOEpatents

Stoddard, Nathan G

2013-11-26

Methods are provided for casting one or more of a semi-conductor, an oxide, and an intermetallic material. With such methods, a cast body of a geometrically ordered multi-crystalline form of the one or more of a semiconductor, an oxide, and an intermetallic material may be formed that is free or substantially free of radially-distributed impurities and defects and having at least two dimensions that are each at least about 10 cm.

Methods for manufacturing monocrystalline or near-monocrystalline cast materials

DOEpatents

Stoddard, Nathan G

2014-04-29

Methods are provided for casting one or more of a semiconductor, an oxide, and an intermetallic material. With such methods, a cast body of a monocrystalline form of the one or more of a semiconductor, an oxide, and an intermetallic material may be formed that is free of, or substantially free of, radially-distributed impurities and defects and having at least two dimensions that are each at least about 35 cm.

Osteochondral Repair Using Porous Three-dimensional Nanocomposite Scaffolds in a Rabbit Model.

PubMed

Żylińska, Beata; Stodolak-Zych, Ewa; Sobczyńska-Rak, Aleksandra; Szponder, Tomasz; Silmanowicz, Piotr; Łańcut, Mirosław; Jarosz, Łukasz; Różański, Paweł; Polkowska, Izabela

2017-01-01

To evaluate the utility of a novel nanocomposite biomaterial consisting of poly-L/D-lactide, and hydroxyapatite bioceramics, enriched with sodium alginate in articular cartilage defect treatment. The biomaterial was prepared using the method of solvent casting and particle leaching. The study was conducted on 20 New Zealand White rabbits. Experimental osteochondral defects were created in the femoral trochlear grooves and filled with biomaterials. In control groups, the defects were left to spontaneously heal. The quality of newly-formed tissue was evaluated on the basis of macroscopic and histological assessment. Additionally the level of osteogenic and cartilage degradation markers were measured. The majority of the defects from the treatment group were covered with tissue similar in structure and colour to healthy cartilage, whereas in the control group, tissue was uneven, and not integrated into the surrounding cartilage. The results obtained validate the choice of biomaterial used in this study as well as the method of its application. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

Ultrahigh Molecular Weight Linear Block Copolymers: Rapid Access by Reversible-Deactivation Radical Polymerization and Self- Assembly into Large Domain Nanostructures

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

Mapas, Jose Kenneth D.; Thomay, Tim; Cartwright, Alexander N.

2016-05-05

Block copolymer (BCP) derived periodic nanostructures with domain sizes larger than 150 nm present a versatile platform for the fabrication of photonic materials. So far, the access to such materials has been limited to highly synthetically involved protocols. Herein, we report a simple, “user-friendly” method for the preparation of ultrahigh molecular weight linear poly(solketal methacrylate-b-styrene) block copolymers by a combination of Cu-wire-mediated ATRP and RAFT polymerizations. The synthesized copolymers with molecular weights up to 1.6 million g/mol and moderate dispersities readily assemble into highly ordered cylindrical or lamella microstructures with domain sizes as large as 292 nm, as determined bymore » ultra-small-angle x-ray scattering and scanning electron microscopy analyses. Solvent cast films of the synthesized block copolymers exhibit stop bands in the visible spectrum correlated to their domain spacings. The described method opens new avenues for facilitated fabrication and the advancement of fundamental understanding of BCP-derived photonic nanomaterials for a variety of applications.« less

Solvent Effects of Model Polymeric Corrosion Control Coatings on Water Transport and Corrosion Rate

NASA Astrophysics Data System (ADS)

Konecki, Christina

Industrial coating formulations are often made for volatile organic content compliance and ease of application, with little regard for the solvent impact on resultant performance characteristics. Our research objective was to understand the effect of both solvent retention and chemical structure on water transport through polymer films and resultant corrosion area growth of coated steel substrates. A clear, unpigmented Phenoxy(TM) thermoplastic polymer (PKHH) was formulated into resin solutions with three separate solvent blends selected by Hansen solubility parameter (HSP), boiling point, and ability to solubilize PKHH. Polymer films cast from MEK/PGME (methyl ethyl ketone/ propylene glycol methyl ether), dried under ambient conditions (AMB, > 6wt.% residual solvent) produced a porous morphology, which resulted in a corrosion area greater than 50%. We attributed this to the water-soluble solvent used in film preparation, which enabled residual PGME to be extracted by water. The resin solution prepared with CYCOH/DXL (Cyclohexanol/ 1,3 dioxolane) was selected because CYCOH is a solid at room temperature which acts as a pigment in the final film. Therefore, increasing the tortuosity of water transport, as well as a high hydrogen bonding character, which caused more interactions with water, slowing diffusion, producing a nodular morphology, and 37% less corrosion area than MEK/PGME AMB. The HSP of PKHH and EEP (ethyl 3-ethoxypropionate) are within 5% of each other, which produced a homogeneous morphology and resulted in comparable corrosion rates regardless of residual solvent content. We utilized electrochemical techniques and attenuated total reflectance- Fourier transform infrared spectroscopy to elucidate dynamic water absorption and solvent extraction in the exposed model formulations. We found that water absorption resulted in a loss of barrier properties, and increased corrosion due to the voids formed by solvent extraction. The polymer films were rejuvenated (removal of water) as an attempt to decrease the number of water transport pathways during exposure. Results found that samples rejuvenated at temperatures above the glass transition temperature of the samples achieved lower moisture content and consequently, lower corrosion growth rates. In commercial systems, rejuvenation lowered the corrosion rate up to 60% indicating better coating formulations and maintenance cycles would control the corrosion rate.

Transport of organic solutes through amorphous teflon AF films.

PubMed

Zhao, Hong; Zhang, Jie; Wu, Nianqiang; Zhang, Xu; Crowley, Katie; Weber, Stephen G

2005-11-02

Fluorous media have great potential for selective extraction (e.g., as applied to organic synthesis). Fluorous polymer films would have significant advantages in fluorous separations. Stable films of Teflon AF 2400 were cast from solution. Films appear defect-free (SEM; AFM). Rigid aromatic solutes are transported (from chloroform solution to chloroform receiving phase) in a size-dependent manner (log permeability is proportional to -0.0067 times critical volume). Benzene's permeability is about 2 orders of magnitude higher than in comparable gas-phase experiments. The films show selectivity for fluorinated solutes in comparison to the hydrogen-containing control. Transport rates are dependent on the solvent making up the source and receiving phases. The effect of solvent is, interestingly, not due to changes in partition ratio, but rather it is due to changes in the solute diffusion coefficient in the film. Solvents plasticize the films. A less volatile compound, -COOH-terminated poly(hexafluoropropylene oxide) (4), plasticizes the films (T(g) = -40 degrees C). Permeabilities are decreased in comparison to 4-free films apparently because of decreased diffusivity of solutes. The slope of dependence of log permeability on critical volume is not changed, however.

Systems and methods for monitoring a solid-liquid interface

DOEpatents

Stoddard, Nathan G; Lewis, Monte A.; Clark, Roger F

2013-06-11

Systems and methods are provided for monitoring a solid-liquid interface during a casting process. The systems and methods enable determination of the location of a solid-liquid interface during the casting process.

Three-dimensional microstructure simulation of Ni-based superalloy investment castings

NASA Astrophysics Data System (ADS)

Pan, Dong; Xu, Qingyan; Liu, Baicheng

2011-05-01

An integrated macro and micro multi-scale model for the three-dimensional microstructure simulation of Ni-based superalloy investment castings was developed, and applied to industrial castings to investigate grain evolution during solidification. A ray tracing method was used to deal with the complex heat radiation transfer. The microstructure evolution was simulated based on the Modified Cellular Automaton method, which was coupled with three-dimensional nested macro and micro grids. Experiments for Ni-based superalloy turbine wheel investment casting were carried out, which showed a good correspondence with the simulated results. It is indicated that the proposed model is able to predict the microstructure of the casting precisely, which provides a tool for the optimizing process.

Flexible continuous manufacturing platforms for solid dispersion formulations

NASA Astrophysics Data System (ADS)

Karry-Rivera, Krizia Marie

In 2013 16,000 people died in the US due to overdose from prescription drugs and synthetic narcotics. As of that same year, 90% of new molecular entities in the pharmaceutical drug pipeline are classified as poor water-soluble. The work in this dissertation aims to design, develop and validate platforms that solubilize weak acids and can potentially deter drug abuse. These platforms are based on processing solid dispersions via solvent-casting and hot-melt extrusion methods to produce oral transmucosal films and melt tablets. To develop these platforms, nanocrystalline suspensions and glassy solutions were solvent-casted in the form of films after physicochemical characterizations of drug-excipient interactions and design of experiment approaches. A second order model was fitted to the emulsion diffusion process to predict average nanoparticle size and for process optimization. To further validate the manufacturing flexibility of the formulations, glassy solutions were also extruded and molded into tablets. This process included a systematic quality-by-design (QbD) approach that served to identify the factors affecting the critical quality attributes (CQAs) of the melt tablets. These products, due to their novelty, lack discriminatory performance tests that serve as predictors to their compliance and stability. Consequently, Process Analytical Technology (PAT) tools were integrated into the continuous manufacturing platform for films. Near-infrared (NIR) spectroscopy, including chemical imaging, combined with deconvolution algorithms were utilized for a holistic assessment of the effect of formulation and process variables on the product's CQAs. Biorelevant dissolution protocols were then established to improve the in-vivo in-vitro correlation of the oral transmucosal films. In conclusion, the work in this dissertation supports the delivery of poor-water soluble drugs in products that may deter abuse. Drug nanocrystals ensured high bioavailability, while glassy solutions enabled drug solubilization in polymer matrices. PAT tools helped in characterizing the micro and macro structure of the product while also used as a control strategy for manufacturing. The systematic QbD assessment enabled identification of the variables that significantly affected melt tablet performance and their potential as an abuse deterrent product. Being that these glassy products are novel systems, biorelevant protocols for testing dissolution performance of films were also developed.

Cast erosion from the cleaning of debris after the use of a cast trimmer.

PubMed

Hansen, Paul A; Beatty, Mark W

2017-02-01

Whether using tap water to rinse off debris will make a clinical difference to the surface detail of a gypsum cast is unknown. In addition, how best to remove debris from the cast is unknown. The purpose of this in vitro study was to evaluate the efficiency of different methods of cleaning a gypsum cast after trimming and the effect of short-term exposure to tap water on the surface quality of the cast. A die fitting American National Standards Institute/American Dental Association specification 25 (International Standards Organization specification 6873) for dental gypsum products was embedded in a Dentoform with the machined lines positioned at the same level as the occlusal surface of the posterior teeth. A flat plate was used to ensure that the plane of occlusion for the die was at the same position as the posterior teeth. Forty polyvinyl siloxane impressions of the Dentoform were made and poured with vacuum-mixed improved Type IV dental stone. Each cast was inspected for the accurate reproduction of the lines. The base of the 2-stage pour was trimmed with a cast trimmer with water, and surface debris was removed by rinsing by hand under tap water for 10 seconds, by brushing the cast with a soft toothbrush for 10 seconds, or by resoaking the cast and using a soft camel hair brush in slurry water for 10 seconds. The amount of debris was evaluated on a scale of 1 to 4, and the quality of the 20-μm line was evaluated on a scale of 1 to 4 under ×15 magnification. The nonparametric Kruskal-Wallis ranks test was used to identify significant differences among the different cleaning methods (α=.05). Results of the Kruskal-Wallis and Kruskal-Wallis Z-value tests demonstrated that all cleaning methods produced cleaner casts than were observed for uncleansed controls (P<.001), but no differences in debris removal were found among the different cleaning methods (.065≤P≤.901). The ability to see the quality of a 20-μm line (P=.974) was not statistically different among the groups. Rinsing the cast under flowing tap water and brushing, or hand washing under flowing tap water, or using a soft camel hair brush in slurry water for 10 seconds had no noticeable effects on the quality of a 20-μm line, and all 3 methods resulted in a clean cast. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Timing of Getter Material Addition in Cementitious Wasteforms

NASA Astrophysics Data System (ADS)

Lawter, A.; Qafoku, N. P.; Asmussen, M.; Neeway, J.; Smith, G. L.

2015-12-01

A cementitious waste form, Cast Stone, is being evaluated as a possible supplemental immobilization technology for the Hanford sites's low activity waste (LAW), which contains radioactive 99Tc and 129I, as part of the tank waste cleanup mission. Cast Stone is made of a dry blend 47% blast furnace slag, 45% fly ash, and 8% ordinary Portland cement, mixed with a low-activity waste (LAW). To improve the retention of Tc and/or I in Cast Stone, materials with a high affinity for Tc and/or I, termed "getters," can be added to provide a stable domain for the radionuclides of concern. Previous testing conducted with a variety of getters has identified Tin(II)-Apatite and Silver Exchanged Zeolite as promising candidates for Tc and I, respectively. Investigation into the sequence in which getters are added to Cast Stone was performed following two methods: 1) adding getters to the Cast Stone dry blend, and then mixing with liquid waste, and 2) adding getters to the liquid waste first, followed by addition of the Cast Stone dry blend. Cast Stone monolith samples were prepared with each method and leach tests, following EPA method 1315, were conducted in either distilled water or simulated vadose zone porewater for a period of up to 63 days. The leachate was analyzed for Tc, I, Na, NO3-, NO2- and Cr with ICP-MS, ICP-OES and ion chromatography and the results indicated that the Cast Stone with getter addition in the dry blend mix (method 1) has lower rates of Tc and I leaching. The mechanisms of radionuclide release from the Cast Stone were also investigated with a variety of solid phase characterization techniques of the monoliths before and after leaching, such as XRD, SEM/EDS, TEM/SAED and other spectroscopic techniques.

The application of multi-baseline digital close-range photogrammetry in three-dimensional imaging and measurement of dental casts.

PubMed

Fu, Xiaoming; Peng, Chun; Li, Zan; Liu, Shan; Tan, Minmin; Song, Jinlin

2017-01-01

To explore a new technique for reconstructing and measuring three-dimensional (3D) models of orthodontic plaster casts using multi-baseline digital close-range photogrammetry (MBDCRP) with a single-lens reflex camera. Thirty sets of orthodontic plaster casts that do not exhibit severe horizontal overlap (>2 mm) between any two teeth were recorded by a single-lens reflex camera with 72 pictures taken in different directions. The 3D models of these casts were reconstructed and measured using the open source software MeshLab. These parameters, including mesio-distal crown diameter, arch width, and arch perimeter, were recorded six times on both the 3D digital models and on plaster casts by two examiners. Statistical analysis was carried out using the Bland-Altman method to measure agreement between the novel method and the traditional calliper method by calculating the differences between mean values. The average differences between the measurements of the photogrammetric 3D models and the plaster casts were 0.011-0.402mm. The mean differences between measurements obtained by the photogrammetric 3D models and the dental casts were not significant except for the lower arch perimeter (P>0.05), and all the differences were regarded as clinically acceptable (<0.5 mm). Measurements obtained by MBDCRP are compared well with those obtained from plaster casts, indicating that MBDCRP is an alternate way to store and measure dental plaster casts without severe horizontal overlap between any two teeth.

The Design of 3D-Printed Lattice-Reinforced Thickness-Varying Shell Molds for Castings

PubMed Central

Shangguan, Haolong; Kang, Jinwu; Yi, Jihao; Zhang, Xiaochuan; Wang, Xiang; Wang, Haibin; Huang, Tao

2018-01-01

3D printing technologies have been used gradually for the fabrication of sand molds and cores for castings, even though these molds and cores are dense structures. In this paper, a generation method for lattice-reinforced thickness-varying shell molds is proposed and presented. The first step is the discretization of the STL (Stereo Lithography) model of a casting into finite difference meshes. After this, a shell is formed by surrounding the casting with varying thickness, which is roughly proportional to the surface temperature distribution of the casting that is acquired by virtually cooling it in the environment. A regular lattice is subsequently constructed to support the shell. The outside surface of the shell and lattice in the cubic mesh format is then converted to STL format to serve as the external surface of the new shell mold. The internal surface of the new mold is the casting’s surface with the normals of all of the triangles in STL format reversed. Experimental verification was performed on an Al alloy wheel hub casting. Its lattice-reinforced thickness-varying shell mold was generated by the proposed method and fabricated by the binder jetting 3D printing. The poured wheel hub casting was sound and of good surface smoothness. The cooling rate of the wheel hub casting was greatly increased due to the shell mold structure. This lattice-reinforced thickness-varying shell mold generation method is of great significance for mold design for castings to achieve cooling control. PMID:29601543

Strip casting apparatus and method

DOEpatents

Williams, R.S.; Baker, D.F.

1988-09-20

Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip. 6 figs.

Strip casting apparatus and method

DOEpatents

Williams, Robert S.; Baker, Donald F.

1988-01-01

Strip casting apparatus including a molten-metal-holding container and a nozzle to deposit molten metal onto a moving chill drum to directly cast continuous metallic strip. The nozzle body includes a slot bounded between a back and a front lip. The slot width exceeds about 20 times the gap distance between the nozzle and the chill drum surface. Preferably, the slot width exceeds 0.5 inch. This method of strip casting minimizes pressure drop, insuring better metal-to-chill-drum contact which promotes heat transfer and results in a better quality metallic strip.

Enhanced encapsulation and bioavailability of breviscapine in PLGA microparticles by nanocrystal and water-soluble polymer template techniques.

PubMed

Wang, Hong; Zhang, Guangxing; Ma, Xueqin; Liu, Yanhua; Feng, Jun; Park, Kinam; Wang, Wenping

2017-06-01

Poly (lactide-co-glycolide) (PLGA) microparticles are widely used for controlled drug delivery. Emulsion methods have been commonly used for preparation of PLGA microparticles, but they usually result in low loading capacity, especially for drugs with poor solubility in organic solvents. In the present study, the nanocrystal technology and a water-soluble polymer template method were used to fabricate nanocrystal-loaded microparticles with improved drug loading and encapsulation efficiency for prolonged delivery of breviscapine. Breviscapine nanocrystals were prepared using a precipitation-ultrasonication method and further loaded into PLGA microparticles by casting in a mold from a water-soluble polymer. The obtained disc-like particles were then characterized and compared with the spherical particles prepared by an emulsion-solvent evaporation method. X-ray powder diffraction (XRPD) and confocal laser scanning microscopy (CLSM) analysis confirmed a highly-dispersed state of breviscapine inside the microparticles. The drug form, loading percentage and fabrication techniques significantly affected the loading capacity and efficiency of breviscapine in PLGA microparticles, and their release performance as well. Drug loading was increased from 2.4% up to 15.3% when both nanocrystal and template methods were applied, and encapsulation efficiency increased from 48.5% to 91.9%. But loading efficiency was reduced as the drug loading was increased. All microparticles showed an initial burst release, and then a slow release period of 28days followed by an erosion-accelerated release phase, which provides a sustained delivery of breviscapine over a month. A relatively stable serum drug level for more than 30days was observed after intramuscular injection of microparticles in rats. Therefore, PLGA microparticles loaded with nanocrystals of poorly soluble drugs provided a promising approach for long-term therapeutic products characterized with preferable in vitro and in vivo performance. Copyright © 2017 Elsevier B.V. All rights reserved.

Determining casting defects in near-net shape casting aluminum parts by computed tomography

NASA Astrophysics Data System (ADS)

Li, Jiehua; Oberdorfer, Bernd; Habe, Daniel; Schumacher, Peter

2018-03-01

Three types of near-net shape casting aluminum parts were investigated by computed tomography to determine casting defects and evaluate quality. The first, second, and third parts were produced by low-pressure die casting (Al-12Si-0.8Cu-0.5Fe-0.9Mg-0.7Ni-0.2Zn alloy), die casting (A356, Al-7Si-0.3Mg), and semi-solid casting (A356, Al-7Si-0.3Mg), respectively. Unlike die casting (second part), low-pressure die casting (first part) significantly reduced the formation of casting defects (i.e., porosity) due to its smooth filling and solidification under pressure. No significant casting defect was observed in the third part, and this absence of defects indicates that semi-solid casting could produce high-quality near-net shape casting aluminum parts. Moreover, casting defects were mostly distributed along the eutectic grain boundaries. This finding reveals that refinement of eutectic grains is necessary to optimize the distribution of casting defects and reduce their size. This investigation demonstrated that computed tomography is an efficient method to determine casting defects in near-net shape casting aluminum parts.

Note: Piezoelectric polymers as transducers for the ultrasonic-reflection method and the application in mechanical property-screening of coatings

NASA Astrophysics Data System (ADS)

Wegener, Michael; Oehler, Harald; Lellinger, Dirk; Alig, Ingo

2012-01-01

In the last years, non-destructive ultrasonic testing methods are more and more frequently employed in order to investigate the drying and curing processes of different coatings. Among them an ultrasonic reflection method was developed allowing the simultaneous measurement with longitudinal and transversal waves. In order to generate the ultrasonic pulse, piezoelectric ceramics or oxides are usually used as transducer materials which are connected to a delay line. Here, we demonstrate a similar approach for the ultrasonic reflection method installing piezoelectric polymers as ultrasonic transducer materials. In detail, poly(vinylidene fluoride and trifluoroethylene) [P(VDF-TrFE)] copolymers were prepared as piezoelectric transducer layers directly onto the metallization of glass delay lines avoiding additional bonding processes. The film preparation was carried out by solvent casting the polymer onto an area with a diameter of 12 mm and is optimized so that relatively homogeneous polymer layers with thicknesses between 14 and 35 μm are adjusted by the deposited amount of the polymer. Electrical poling renders the polymer piezoelectric. The ultrasonic properties of the P(VDF-TrFE) transducer and their usability for the ultrasonic reflection method are described also in comparison to previous measurements using LiNbO3 transducer.

SSME Main Combustion Chamber (MCC) hot oil dewaxing

NASA Technical Reports Server (NTRS)

Akpati, Anthony U.

1995-01-01

In an attempt to comply with the changing environmental regulations, a process was developed for the replacement of perchloroethylene in the dewaxing of the Space Shuttle Main Engine (SSME) Main Combustion Chamber (MCC) and other associated hardware filled with the Rigidax (R) casting compound. Rigidax (R) is a hard blue-dyed, calcium carbonate filled thermoplastic casting compound (melting point 77 C) that is melted and poured into hardware cavities to prevent contamination during material removal processes, i.e. machining, grinding, drilling, and deburring. Additionally, it serves as a maskant for designated areas during electroforming processes. Laboratory testing was conducted to evaluate seven alternate fluids for the replacement of perchloroethylene in the dewaxing process. Based upon successful laboratory results, a mineral oil was selected for testing on actual hardware. The final process developed involves simultaneous immersion and flushing of the MCC channels using a distinct eight stage process. A nonvolatile hydrocarbon analysis of a solvent flush sample is performed to determine the hardware cleanliness for comparison to the previous perchloroethylene dewaxing process.

SSME Main Combustion Chamber (MCC) 'Hot Oil' Dewaxing

NASA Technical Reports Server (NTRS)

Akpati, Anthony U.

1994-01-01

In an attempt to comply with the changing environmental regulations, a process was developed for the replacement of perchloroethylene in the dewaxing of the Space Shuttle Main Engine (SSME) Main Combustion Chamber (MCC) and other associated hardware filled with the Rigidax(registered mark) casting compound. Rigidax(registered mark) is a hard blue-dyed, calcium carbonate filled thermoplastic casting compound (melting point 77 C) that is melted and poured into hardware cavities to prevent contamination during material removal processes, i.e. machining, grinding, drilling, and deburring. Additionally, it serves as a maskant for designated areas during electroforming processes. Laboratory testing was conducted to evaluate seven alternate fluids for the replacement of perchloroethylene in the dewaxing process. Based upon successful laboratory results, a mineral oil was selected for testing on actual hardware. The final process developed involves simultaneous immersion and flushing of the MCC channels using a distinct eight stage process. A nonvolatile hydrocarbon analysis of a solvent flush sample is performed to determine the hardware cleanliness for comparison to the previous perchloroethylene dewaxing process.

Indigenous lunar construction materials

NASA Technical Reports Server (NTRS)

Rogers, Wayne; Sture, Stein

1991-01-01

The objectives are the following: to investigate the feasibility of the use of local lunar resources for construction of a lunar base structure; to develop a material processing method and integrate the method with design and construction of a pressurized habitation structure; to estimate specifications of the support equipment necessary for material processing and construction; and to provide parameters for systems models of lunar base constructions, supply, and operations. The topics are presented in viewgraph form and include the following: comparison of various lunar structures; guidelines for material processing methods; cast lunar regolith; examples of cast basalt components; cast regolith process; processing equipment; mechanical properties of cast basalt; material properties and structural design; and future work.

Method For Removing Volatile Components From A Gel-Cast Ceramic Article

DOEpatents

Klug, Frederic Joseph; DeCarr, Sylvia Marie

2004-09-07

A method of removing substantially all of the volatile component in a green, volatile-containing ceramic article is disclosed. The method comprises freezing the ceramic article; and then subjecting the frozen article to a vacuum for a sufficient time to freeze-dry the article. Frequently, the article is heated while being freeze-dried. Use of this method efficiently reduces the propensity for any warpage of the article. The article is often formed from a ceramic slurry in a gel-casting process. A method for fabricating a ceramic core used in investment casting is also described.

The Problems Encountered in a CTEV Clinic: Can Better Casting and Bracing Be Accomplished?

PubMed

Agarwal, Anil; Kumar, Anubrat; Shaharyar, Abbas; Mishra, Madhusudan

2016-09-07

The aim of the study is to create awareness in the practicing health care workers toward the problems encountered during casting and bracing of clubfoot following Ponseti method, and in turn avoid them. Retrospective audit of 6 years' clubfoot clinic records to analyze problems associated with Ponseti method. Problems were encountered in 26 cast and in 6 braced patients. Just 4 patients out of 71 syndromic (5.6%) experienced problems during casting compared with 3% overall incidence. The common problems encountered in casted patients were moisture lesions, hematoma, dermatitis due to occlusion, pressure sores, and fractures. There was excessive bleeding in 1 patient at time of tenotomy. In braced patients, pressure sores and tenderness at tenotomy site were major problems. None of the syndromic patients experienced difficulties during bracing. Problems were encountered with Ponseti method during casting, tenotomy, or bracing. Syndromic children had lesser complication rate than idiopathic clubfeet. It is important to be aware of these problems so that appropriate intervention can be done early. Level IV: Retrospective. © 2016 The Author(s).

Structure-Processing Relationships in Solution Processable Polymer Thin Film Transistors and Small Molecule Bulk Heterojunction Solar Cells

NASA Astrophysics Data System (ADS)

Perez, Louis A.

A regio-regular (RR) conjugated copolymer based on cyclopenta[2,1-b:3,4- b]dithiophene (CDT) and pyridal[2,1,3]thiadiazole (PT) structural units was prepared by using polymerization reactions involving reactants specifically designed to avoid random orientation of the asymmetric PT heterocycle. Compared to its regio-irregular (RI) counterpart, the RR polymer exhibits a two orders of magnitude increase in hole mobility from 0.005 to 0.6 cm2V -1s-1. To probe the reason for this difference in mobility, we examined the crystalline structure and its orientation in thin films of both copolymers as a function of depth via grazing incidence wide angle X-ray scattering (GIWAXS). In the RI film, the pi-pi stacking direction of the crystallites is mainly perpendicular to the substrate normal (edge-on orientation) while in the RR film the crystallites adopt a mixed pi-pi stacking orientation in the center of the film as well as near the interface between the polymer and the dielectric layer. These results demonstrate that control of backbone regularity is another important design criterion to consider in the synthesis and optimization of new conjugated copolymers with asymmetric structural units. Solution processed organic photovoltaic devices (OPVs) have emerged as a promising sustainable energy technology due to their ease of fabrication, potential to enable low-cost manufacturing, and ability to be incorporated onto light-weight flexible substrates. To date, the most efficacious OPV device architecture, the bulk heterojunction (BHJ), consists of a blend of a light-harvesting conjugated organic electron donating molecule and a strong electron-accepting compound (usually a soluble fullerene derivative e.g. [6,6]-phenyl C71 butyric acid methyl ester (PC71BM). BHJ layer morphology, which has been shown to be highly dependent on processing, has a significant effect on OPV performance. It is postulated that optimal BHJ morphologies consist of discrete bicontinuous nanoscale domains of each moiety, on the order of the exciton diffusion length, which extend vertically from each electrode, thereby increasing the surface area of the domains and forming continuous conducting pathways for efficient charge extraction and transfer. An optimal morphology, however, is seldom achieved during film formation; therefore, a number of processing techniques, such as thermal and sol vent annealing, and the addition of solvent additives to the casting solution have been explored to control the morphology in order to attain the multiple structural requirements. Solvent additive processing, a technique that is used in most record performing polymer:fullerene BHJ solar cell devices, involves the addition of small volumes of a high boiling point liquid to the BHJ casting solu- tion. Solvent additive processing, with 1,8-diiodooctane (DIO) as the additive, has recently been employed in solution processable small molecule (SPSM) BHJ systems, showing similar drastic effects on several device metrics and ultimately the power conversion efficiency (PCE). A recent SPSM study delineates how the volume of solvent additive used affects device performance: when 0.4 v/v% of DIO was used, the PCE increased from 1.8 to 7%, while a deterioration in the PCE to less than 1% occurred when only 1 v/v% of DIO was used. Several structural characterization techniques, such as grazing incidence wide and small-angle X-ray scattering (GIWAXS and GISAXS), and energy filtered transmission electron microscopy (EF-TEM), were used to investigate structure-processing-property relationships in additive-treated SPSM BHJ films and were correlated to device performance. Scattering experiments showed that the use of additives had several effects on the structure of the BHJ at multiple length scales: e.g. the number and orientation of SPSM crystallites, different pi-pi stacking distances, and the nano-scale domain size. Additionally, EF-TEM further verified the effect of additives on the domain size and was complemented with tomographic reconstructions to provide a 3D representation of the BHJ morphology due to solvent additive processing. Finally, in situ GIWAXS was also performed to investigate the kinetics of crystallite formation during and shortly after spin-casting. The additive was shown to induce a complex structural evolution effect on the microstructure of SPSMs by inciting the formation of a metastable polymorph and enhanced crystalline quality of the SPSM during and shortly after casting, whereas the non-additive treated SPSM structure was static after initial crystallite formation. The results from this study have important implications for future optimization and design of solvent additive processed SPSM BHJ blends for OPV devices.

Growth directions of C8-BTBT thin films during drop-casting

NASA Astrophysics Data System (ADS)

Iizuka, Naoki; Zanka, Tomohiko; Onishi, Yosuke; Fujieda, Ichiro

2016-02-01

Because charge transport in a single crystal is anisotropic, control of its orientation is important for enhancing electrical characteristics and reducing variations among devices. For growing an organic thin film, a solution process such as inkjet printing offers advantages in throughput. We have proposed to apply an external temperature gradient during drop-casting and to control the direction of solvent evaporation. In experiment, a temperature gradient was generated in a bare Si substrate by placing it on a Si plate bridging two heat stages. When a solution containing 2,7-dioctyl [1]benzothieno[3,2-b]benzothiophene (C8-BTBT) was dropped on the substrate, evaporation started at the hotter side of the droplet and proceeded toward the colder side. The front line of the liquid was not pinned and the solution extended toward the colder region. As a result, a thin film was formed in a 7mm-long region. The peripheral region of the film was significantly thicker due to the coffee ring effect. The surface of the rest of the film was mostly smooth and terrace structures with 2.6nm steps were observed. The step roughly corresponds to the length of the C8-BTBT molecule. The film thickness varied from 20nm to 50nm over the distance of 3mm. Another film was grown on a glass substrate under a similar condition. Observation of the film with a polarizing microscope revealed that fan-shaped domains were formed in the film and that their optical axes were mostly along the directions of the solvent evaporation.

Tape-cast sensors and method of making

DOEpatents

Mukundan, Rangachary [Santa Fe, NM; Brosha, Eric L [Los Alamos, NM; Garzon, Fernando H [Santa Fe, NM

2009-08-18

A method of making electrochemical sensors in which an electrolyte material is cast into a tape. Prefabricated electrodes are then partially embedded between two wet layers of the electrolyte tape to form a green sensor, and the green sensor is then heated to sinter the electrolyte tape around the electrodes. The resulting sensors can be used in applications such as, but not limited to, combustion control, environmental monitoring, and explosive detection. A electrochemical sensor formed by the tape-casting method is also disclosed.

A new method to acquire 3-D images of a dental cast

NASA Astrophysics Data System (ADS)

Li, Zhongke; Yi, Yaxing; Zhu, Zhen; Li, Hua; Qin, Yongyuan

2006-01-01

This paper introduced our newly developed method to acquire three-dimensional images of a dental cast. A rotatable table, a laser-knife, a mirror, a CCD camera and a personal computer made up of a three-dimensional data acquiring system. A dental cast is placed on the table; the mirror is installed beside the table; a linear laser is projected to the dental cast; the CCD camera is put up above the dental cast, it can take picture of the dental cast and the shadow in the mirror; while the table rotating, the camera records the shape of the laser streak projected on the dental cast, and transmit the data to the computer. After the table rotated one circuit, the computer processes the data, calculates the three-dimensional coordinates of the dental cast's surface. In data processing procedure, artificial neural networks are enrolled to calibrate the lens distortion, map coordinates form screen coordinate system to world coordinate system. According to the three-dimensional coordinates, the computer reconstructs the stereo image of the dental cast. It is essential for computer-aided diagnosis and treatment planning in orthodontics. In comparison with other systems in service, for example, laser beam three-dimensional scanning system, the characteristic of this three-dimensional data acquiring system: a. celerity, it casts only 1 minute to scan a dental cast; b. compact, the machinery is simple and compact; c. no blind zone, a mirror is introduced ably to reduce blind zone.

Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study

PubMed Central

Alex, Deepa; Shetty, Y. Bharath; Miranda, Glynis Anita; Prabhu, M. Bharath; Karkera, Reshma

2015-01-01

Background: Conventional investing and casting techniques are time-consuming and usually requires 2–4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30–40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique. Materials and Methods: A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope. Results: The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm). Conclusion: The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had shown the least vertical marginal discrepancies among the four methods evaluated in this study. PMID:26929488

Materials for Advanced Ultrasupercritical Steam Turbines Task 4: Cast Superalloy Development

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

Thangirala, Mani

The Steam Turbine critical stationary structural components are high integrity Large Shell and Valve Casing heavy section Castings, containing high temperature steam under high pressures. Hence to support the development of advanced materials technology for use in an AUSC steam turbine capable of operating with steam conditions of 760°C (1400°F) and 35 Mpa (5000 psia), Casting alloy selection and evaluation of mechanical, metallurgical properties and castability with robust manufacturing methods are mandated. Alloy down select from Phase 1 based on producability criteria and creep rupture properties tested by NETL-Albany and ORNL directed the consortium to investigate cast properties of Haynesmore » 282 and Haynes 263. The goals of Task 4 in Phase 2 are to understand a broader range of mechanical properties, the impact of manufacturing variables on those properties. Scale up the size of heats to production levels to facilitate the understanding of the impact of heat and component weight, on metallurgical and mechanical behavior. GE Power & Water Materials and Processes Engineering for the Phase 2, Task 4.0 Castings work, systematically designed and executed casting material property evaluation, multiple test programs. Starting from 15 lbs. cylinder castings to world’s first 17,000 lbs. poured weight, heavy section large steam turbine partial valve Haynes 282 super alloy casting. This has demonstrated scalability of the material for steam Turbine applications. Activities under Task 4.0, Investigated and characterized various mechanical properties of Cast Haynes 282 and Cast Nimonic 263. The development stages involved were: 1) Small Cast Evaluation: 4 inch diam. Haynes 282 and Nimonic 263 Cylinders. This provided effects of liquidus super heat range and first baseline mechanical data on cast versions of conventional vacuum re-melted and forged Ni based super alloys. 2) Step block castings of 300 lbs. and 600 lbs. Haynes 282 from 2 foundry heats were evaluated which demonstrated the importance of proper heat treat cycles for Homogenization, and Solutionizing parameters selection and implementation. 3) Step blocks casting of Nimonic 263: Carried out casting solidification simulation analysis, NDT inspection methods evaluation, detailed test matrix for Chemical, Tensile, LCF, stress rupture, CVN impact, hardness and J1C Fracture toughness section sensitivity data and were reported. 4) Centrifugal Casting of Haynes 282, weighing 1400 lbs. with hybrid mold (half Graphite and half Chromite sand) mold assembly was cast using compressor casing production tooling. This test provided Mold cooling rates influence on centrifugally cast microstructure and mechanical properties. Graphite mold section out performs sand mold across all temperatures for 0.2% YS; %Elongation, %RA, UTS at 1400°F. Both Stress-LMP and conditional Fracture toughness plots data were in the scatter band of the wrought alloy. 5) Fundamental Studies on Cooling rates and SDAS test program. Evaluated the influence of 6 mold materials Silica, Chromite, Alumina, Silica with Indirect Chills, Zircon and Graphite on casting solidification cooling rates. Actual Casting cooling rates through Liquidus to Solidus phase transition were measured with 3 different locations based thermocouples placed in each mold. Compared with solidification simulation cooling rates and measurement of SDAS, microstructure features were reported. The test results provided engineered casting potential methods, applicable for heavy section Haynes 282 castings for optimal properties, with foundry process methods and tools. 6) Large casting of Haynes 282 Drawings and Engineering FEM models and supplemental requirements with applicable specifications were provided to suppliers for the steam turbine proto type feature valve casing casting. Molding, melting and casting pouring completed per approved Manufacturing Process Plan during 2014 Q4. The partial valve casing was successfully cast after casting methods were validated with solidification simulation analysis and the casting met NDT inspection and acceptance criteria. Heat treated and sectioned to extract trepan samples at different locations comparing with cast on coupons test data. Material properties requisite for design, such as tensile, creep/rupture, LCF, Fracture Toughness, Charpy V-notch chemical analysis testing were carried out. The test results will be presented in the final report. The typical Haynes 282 large size Steam Turbine production casting from Order to Delivery foundry schedule with the activity break up is shown in Figures 107 and 108. • From Purchase Order placement to Casting pouring ~ 26 weeks. 1. Sales and commercial review 3 2. Engineering Drawings/models review 4 3. Pattern and core box manufacturing 6 4. Casting process engineering review 4 5. FEM and solidification simulation analysis 4 6. Gating & Feeder Attachments, Ceramic tiling 2 7. Molding and coremaking production scheduling 6 8. Melting planning and schedule 3 9. Pouring, cooling and shake out 2 • From Pouring to casting Delivery ~ 29 weeks 10. Shot blast and riser cutting, gates removal 3 11. Homogenizing , solutionizing HT furnace prep 4 12. Grinding, Fettling 2 13. Aging HT Cycle, cooling 2 14. VT and LPT NDT inspections 2 15. Radiographic inspection 4 16. Mechanical testing, Chemical analysis test certs 4 17. Casting weld repair upgrades and Aging PWHT 4 18. NDT after weld repairs and casting upgrades 3 19. Casting Final Inspection and test certifications 3 20. Package and delivery 2 Hence the Total Lead time from P.O to Casting delivery is approximately 55 weeks. The Task 4.2 and Task 4.3 activities and reporting completed.« less

Used Solvent Testing and Reclamation. Volume 2. Vapor Degreasing and Precision Cleaning Solvents

DTIC Science & Technology

1988-12-01

of 5 to 500 ppm in halogenated solvents using Karl - Fischer reagent. Arbitrary criteria to identify a spent solvent have evolved in various industries... methods of managing waste solvent. Some DOD installations are reclaiming used solvents rather than discarding them. Reclamation is feasible because the...most E E CT E reliable methods for testing solvent quality. Further testing isnecessary for chlorinated solvents to determine the inhibitor con- FEB 24

The application of multi-baseline digital close-range photogrammetry in three-dimensional imaging and measurement of dental casts

PubMed Central

Li, Zan; Liu, Shan; Tan, Minmin; Song, Jinlin

2017-01-01

Objective To explore a new technique for reconstructing and measuring three-dimensional (3D) models of orthodontic plaster casts using multi-baseline digital close-range photogrammetry (MBDCRP) with a single-lens reflex camera. Study design Thirty sets of orthodontic plaster casts that do not exhibit severe horizontal overlap (>2 mm) between any two teeth were recorded by a single-lens reflex camera with 72 pictures taken in different directions. The 3D models of these casts were reconstructed and measured using the open source software MeshLab. These parameters, including mesio-distal crown diameter, arch width, and arch perimeter, were recorded six times on both the 3D digital models and on plaster casts by two examiners. Statistical analysis was carried out using the Bland–Altman method to measure agreement between the novel method and the traditional calliper method by calculating the differences between mean values. Results The average differences between the measurements of the photogrammetric 3D models and the plaster casts were 0.011–0.402mm. The mean differences between measurements obtained by the photogrammetric 3D models and the dental casts were not significant except for the lower arch perimeter (P>0.05), and all the differences were regarded as clinically acceptable (<0.5 mm). Conclusions Measurements obtained by MBDCRP are compared well with those obtained from plaster casts, indicating that MBDCRP is an alternate way to store and measure dental plaster casts without severe horizontal overlap between any two teeth. PMID:28640827

A novel method to acquire 3D data from serial 2D images of a dental cast

NASA Astrophysics Data System (ADS)

Yi, Yaxing; Li, Zhongke; Chen, Qi; Shao, Jun; Li, Xinshe; Liu, Zhiqin

2007-05-01

This paper introduced a newly developed method to acquire three-dimensional data from serial two-dimensional images of a dental cast. The system consists of a computer and a set of data acquiring device. The data acquiring device is used to take serial pictures of the a dental cast; an artificial neural network works to translate two-dimensional pictures to three-dimensional data; then three-dimensional image can reconstruct by the computer. The three-dimensional data acquiring of dental casts is the foundation of computer-aided diagnosis and treatment planning in orthodontics.

[Evaluation method with radiographic image quality indicator for internal defects of dental casting metallic restoration].

PubMed

Li, Y; Zheng, G; Lin, H

2014-12-18

To develop a new kind of dental radiographic image quality indicator (IQI) for internal quality of casting metallic restoration to influence on its usage life. Radiographic image quality indicator method was used to evaluate the depth of the defects region and internal quality of 127 casting metallic restoration and the accuracy was compared with that of conventional callipers method. In the 127 cases of casting metallic restoration, 9 were found the thickness less than 0.7 mm and the thinnest thickness only 0.2 mm in 26 casting metallic crowns or bridges' occlusal defects region. The data measured by image quality indicator were consistent with those measured by conventional gauging. Two metal inner crowns were found the thickness less than 0.3 mm in 56 porcelain crowns or bridges. The thickness of casting removable partial denture was more than 1.0 mm, but thinner regions were not found. It was found that in a titanium partial denture, the X-ray image of clasp was not uniform and there were internal porosity defects in the clasp. Special dental image quality indicator can solve the visual error problems caused by different observing backgrounds and estimate the depth of the defects region in the casting.

Fabrication of silk fibroin film using centrifugal casting technique for corneal tissue engineering.

PubMed

Lee, Min Chae; Kim, Dong-Kyu; Lee, Ok Joo; Kim, Jung-Ho; Ju, Hyung Woo; Lee, Jung Min; Moon, Bo Mi; Park, Hyun Jung; Kim, Dong Wook; Kim, Su Hyeon; Park, Chan Hum

2016-04-01

Films prepared from silk fibroin have shown potential as biomaterials in tissue engineering applications for the eye. Here, we present a novel process for fabrication of silk fibroin films for corneal application. In this work, fabrication of silk fibroin films was simply achieved by centrifugal force. In contrast to the conventional dry casting method, we carried out the new process in a centrifuge with a rotating speed of 4000 rpm, where centrifugal force was imposed on an aluminum tube containing silk fibroin solution. In the present study, we also compared the surface roughness, mechanical properties, transparency, and cell proliferation between centrifugal and dry casting method. In terms of surface morphology, films fabricated by the centrifugal casting have less surface roughness than those by the dry casting. For elasticity and transparency, silk fibroin films obtained from the centrifugal casting had favorable results compared with those prepared by dry casting. Furthermore, primary human corneal keratocytes grew better in films prepared by the centrifugal casting. Therefore, our results suggest that this new fabrication process for silk fibroin films offers important potential benefits for corneal tissue regeneration. © 2015 Wiley Periodicals, Inc.

Fabrication of titanium removable dental prosthesis frameworks with a 2-step investment coating method.

PubMed

Koike, Mari; Hummel, Susan K; Ball, John D; Okabe, Toru

2012-06-01

Although pure titanium is known to have good biocompatibility, a titanium alloy with better strength is needed for fabricating clinically acceptable, partial removable dental prosthesis (RDP) frameworks. The mechanical properties of an experimental Ti-5Al-5Cu alloy cast with a 2-step investment technique were examined for RDP framework applications. Patterns for tests for various properties and denture frameworks for a preliminary trial casting were invested with a 2-step coating method using 2 types of mold materials: a less reactive spinel compound (Al(2)O(3)·MgO) and a less expensive SiO(2)-based material. The yield and tensile strength (n=5), modulus of elasticity (n=5), elongation (n=5), and hardness (n=8) of the cast Ti-5Al-5Cu alloy were determined. The external appearance and internal porosities of the preliminary trial castings of denture frameworks (n=2) were examined with a conventional dental radiographic unit. Cast Ti-6Al-4V alloy and commercially pure titanium (CP Ti) were used as controls. The data for the mechanical properties were statistically analyzed with 1-way ANOVA (α=.05). The yield strength of the cast Ti-5Al-5Cu alloy was 851 MPa and the hardness was 356 HV. These properties were comparable to those of the cast Ti-6Al-4V and were higher than those of CP Ti (P<.05). One of the acrylic resin-retention areas of the Ti-5Al-5Cu frameworks was found to have been incompletely cast. The cast biocompatible experimental Ti-5Al-5Cu alloy exhibited high strength when cast with a 2-step coating method. With a dedicated study to determine the effect of sprue design on the quality of castings, biocompatible Ti-5Al-5Cu RDP frameworks for a clinical trial can be produced. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

PROTECTIVELY COVERED ARTICLE AND METHOD OF MANUFACTURE

DOEpatents

Plott, R.F.

1958-10-28

A method of casting a protective jacket about a ura nium fuel element that will bond completely to the uranium without the use of stringers or supports that would ordinarily produce gaps in the cast metal coating and bond is presented. Preformed endcaps of alumlnum alloyed with 13% silicon are placed on the ends of the uranium fuel element. These caps will support the fuel element when placed in a mold. The mold is kept at a ing alloy but below that of uranium so the cast metal jacket will fuse with the endcaps forming a complete covering and bond to the fuel element, which would otherwise oxidize at the gaps or discontinuities lefi in the coating by previous casting methods.

A simple technique to prolong molding time during application of a fiberglass cast: An in vitro study

PubMed Central

Ayzenberg, Mark; Narvaez, Michael; Raphael, James

2018-01-01

Casting is routinely used for acute and post-operative immobilization and remains a cornerstone in the non-operative management of fractures and deformities. The application of a properly fitted and wellmolded cast, especially for a trainee, can be challenging. We present a simple method of prolonging cure time of fiberglass cast — placing ice in the dip water. Eight-ply, fiveinch fiberglass cast was circumferentially applied to an aluminum-wrapped cardboard cylinder. An electronic, 2-channel temperature sensor (TR-71wf Temp Logger, T&D Corporation, Matsumoto, Japan), accurate to 0.1ºC and accurate to ±0.3ºC, was placed between the fourth and fifth layers of fiberglass. Thirty total casts were tested using 9±1ºC (cold), 22±1ºC (ambient), and 36±1ºC (warm) dip water. Room temperature was maintained at 24±1ºC. Cast temperatures were measured during the exothermic reaction generated by the cast curing. Peak temperatures and cure times were recorded. Cure time was defined as the point of downward deflection on the timetemperature curve immediately after peak. Cure and peak temperatures were compared among groups using analysis of variance. Mean cure time was 3.5±0.1 minutes for warm water, 5.0±0.4 minutes for ambient water and 7.0±0.5 minutes for cold water. Peak temperature, measured between layers 4 and 5 of the cast material, was 36.6±0.8ºC for warm water, 31.1±1.4ºC for ambient water and 25.2±0.5ºC for cold water. Cold afforded, on average, an additional 2 minutes (40% increase) in cure time compared to ambient water and an additional 3.5 minutes (100% increase) compared to warm water. Cure time differences were significant (P<0.001) for all groups, as were peak temperature differences (P<0.001). Temperatures concerning for development of burns were never reached. Utilizing iced dip water when casting is a simple and effective method to prolong the time available for cast application. Orthopedic residents and trainees may find this useful in learning to fabricate a high quality cast. For the experienced orthopedic surgeon, this method eliminates the need to bridge longlimb casts and facilitates the application of complex casts. PMID:29770174

Vacuum thermal evaporation of polyaniline doped with camphor sulfonic acid

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

Boyne, Devon; Menegazzo, Nicola; Pupillo, Rachel C.

2015-05-15

Intrinsically conducting polymers belong to a class of organic polymers with intriguing electronic and physical properties specifically for electro-optical applications. Significant interest into doped polyaniline (PAni) can be attributed to its high conductivity and environmental stability. Poor dissolution in most solvents has thus far hindered the successful integration of PAni into commercial applications, which in turn, has led to the investigations of various deposition and acidic doping methods. Physical vapor deposition methods, including D.C. magnetron sputtering and vacuum thermal evaporation, have shown exceptional control over physical film properties (thickness and morphology). However, resulting films are less conductive than films depositedmore » by conventional methods (i.e., spin and drop casting) due to interruption of the hyperconjugation of polymer chains. Specifically, vacuum thermal evaporation requires a postdoping process, which results in incorporation of impurities and oxidation of surface moieties. In this contribution, thermally evaporated films, sequentially doped by vacuum evaporation of an organic acid (camphorsulfonic acid, CSA) is explored. Spectroscopic evidence confirms the successful doping of PAni with CSA while physical characterization (atomic force microscopy) suggests films retain good morphology and are not damaged by the doping process. The procedure presented herein also combines other postpreparation methods in an attempt to improve conductivity and/or substrate adhesion.« less

Half-heusler alloys with enhanced figure of merit and methods of making

DOEpatents

Ren, Zhifeng; Yan, Xiao; Joshi, Giri; Chen, Shuo; Chen, Gang; Poudel, Bed; Caylor, James Christopher

2015-06-02

Thermoelectric materials and methods of making thermoelectric materials having a nanometer mean grain size less than 1 micron. The method includes combining and arc melting constituent elements of the thermoelectric material to form a liquid alloy of the thermoelectric material and casting the liquid alloy of the thermoelectric material to form a solid casting of the thermoelectric material. The method also includes ball milling the solid casting of the thermoelectric material into nanometer mean size particles and sintering the nanometer size particles to form the thermoelectric material having nanometer scale mean grain size.

Methods for recovering a solvent from a fluid volume and methods of removing at least one compound from a nonpolar solvent

DOEpatents

Ginosar, Daniel M.; Wendt, Daniel S.; Petkovic, Lucia M.

2014-06-10

A method of removing a nonpolar solvent from a fluid volume that includes at least one nonpolar compound, such as a fat, an oil or a triglyceride, is provided. The method comprises contacting a fluid volume with an expanding gas to expand the nonpolar solvent and form a gas-expanded solvent. The gas-expanded solvent may have a substantially reduced density in comparison to the at least one nonpolar compound and/or a substantially reduced capacity to solubilize the nonpolar compound, causing the nonpolar compounds to separate from the gas-expanded nonpolar solvent into a separate liquid phase. The liquid phase including the at least one nonpolar compound may be separated from the gas-expanded solvent using conventional techniques. After separation of the liquid phase, at least one of the temperature and pressure may be reduced to separate the nonpolar solvent from the expanding gas such that the nonpolar solvent may be recovered and reused.

Porous stable poly(lactic acid)/ethyl cellulose/hydroxyapatite composite scaffolds prepared by a combined method for bone regeneration.

PubMed

Mao, Daoyong; Li, Qing; Bai, Ningning; Dong, Hongzhou; Li, Daikun

2018-01-15

A major challenge in bone tissue engineering is the development of biomimetic scaffolds which should simultaneously meet mechanical strength and pore structure requirements. Herein, we combined technologies of high concentration solvent casting, particulate leaching, and room temperature compression molding to prepare a novel poly(lactic acid)/ethyl cellulose/hydroxyapatite (PLA/EC/HA) scaffold. The functional, structural and mechanical properties of the obtained porous scaffolds were characterized. The results indicated that the PLA/EC/HA scaffolds at the 20wt% HA loading level showed optimal mechanical properties and desired porous structure. Its porosity, contact angle, compressive yield strength and weight loss after 56days were 84.28±7.04%, 45.13±2.40°, 1.57±0.09MPa and 4.77±0.32%, respectively, which could satisfy the physiological demands to guide bone regeneration. Thus, the developed scaffolds have potential to be used as a bone substitute material for bone tissue engineering application. Copyright © 2017. Published by Elsevier Ltd.

The improvement of characteristics of biodegradable films made from kefiran-whey protein by nanoparticle incorporation.

PubMed

Zolfi, Mohsen; Khodaiyan, Faramarz; Mousavi, Mohammad; Hashemi, Maryam

2014-08-30

Biodegradable kefiran-whey protein isolate (WPI) nanocomposites were produced using montmorillonite (MMT) and nano-TiO2 as nanoparticles in the percentage of 1, 3, and 5% (w/w) by a casting and solvent-evaporation method. Physical, mechanical, and water-vapor permeability (WVP) properties were determined as a function of nanoparticle concentration. The results revealed that the effect of these nanoparticles was different according to their nature and percentage. The films incorporated with 5% (w/w) MMT showed the highest tensile strength, Young's modulus, puncture strength, and the lowest WVP compared with the control and TiO2 added films. In contrast to MMT, addition of TiO2 nanoparticles due to the plasticizing effect led to a significant change in color and transparency of nanocomposite. Scanning electron microscopy (SEM) observations demonstrated the films' properties in relation to their microstructures. The surface topography results also showed a considerable increase in roughness parameters by incorporating the nanoparticles in kefiran-WPI matrix. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mechanical, structural and thermal properties of Ag-Cu and ZnO reinforced polylactide nanocomposite films.

PubMed

Ahmed, Jasim; Arfat, Yasir Ali; Castro-Aguirre, Edgar; Auras, Rafael

2016-05-01

Plasticized polylactic acid (PLA) based nanocomposite films were prepared by incorporating polyethylene glycol (PEG) and two selected nanoparticles (NPs) [silver-copper (Ag-Cu) alloy (<100 nm) and zinc oxide (ZnO) (<50 and <100 nm)] through solvent casting method. Incorporation of Ag-Cu alloy into the PLA/PEG matrix increased the glass transition temperature (Tg) significantly. The crystallinity of the nanocomposites (NCs) was significantly influenced by NP incorporation as evidenced from differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The PLA nanocomposite reinforced with NPs exhibited much higher tensile strength than that of PLA/PEG blend. Melt rheology of NCs exhibited a shear-thinning behavior. The mechanical property drastically reduced with a loading of NPs, which is associated with degradation of PLA. SEM micrographs exhibited that both Ag-Cu alloy and ZnO NPs were dispersed well in the PLA film matrix. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparation and Characterization of an Olive Flounder (Paralichthys olivaceus) Skin Gelatin and Polylactic Acid Bilayer Film.

PubMed

Lee, Ka-Yeon; Song, Kyung Bin

2017-03-01

Olive flounder skin gelatin (OSG) was used as a film base material. A bilayer film of OSG and polylactic acid (PLA) was prepared using solvent casting method to enhance the film properties. Physical properties of the OSG-PLA film were increased compared with the nonaugmented OSG film. In particular, the PLA lamination decreased water vapor permeability from 2.17 to 0.92 × 10 -9 g·m/m 2 ·s·Pa, as well as of the water solubility from 16.62% to 9.27%, in the bilayer film relative to the OSG film. The oxygen permeability of the OSG-PLA bilayer film was held low by the OSG film, compensating for the high oxygen permeability of the PLA layer. Therefore, the OSG-PLA bilayer film with its enhanced physical properties and high water and oxygen barrier properties can be applied as a food packaging material. © 2017 Institute of Food Technologists®.

Hydrophilicity and antifouling property of membrane materials from cellulose acetate/polyethersulfone in DMAc.

PubMed

Sun, Zhonghua; Chen, Fushan

2016-10-01

In this study, cellulose acetate (CA) was blended with polyethersulfone (PES) to endow the ultrafiltration membrane with the improved hydrophilicity and antifouling property by using N,N-dimethylacetamide (DMAc) as the solvent. The effects of blend composition and evaporation time on the mechanical strength and pure water flux were investigated. It was found that the optimal composition of the casting solution was: 18wt% (PES), 4wt% (Polyvinylpyrrolidone K30), 3wt% (CA) and 20s (Evaporation time). The characteristics of CA-PES blend membranes were investigated through the methods of contact angle goniometer, antifouling property, compatibility, thermo gravimetric analysis and SEM. The results showed that the hydrophilicity and antifouling property of CA-PES ultrafiltration membranes were enhanced in comparison with the pure PES membranes. The CA-PES membranes exhibited semi-compatibility and good thermal stability below 270°C. This study provided a potential industrial application prospect of CA-PES membranes prepared in DMAc. Copyright © 2016 Elsevier B.V. All rights reserved.

Effect of TiO2 nanoparticles doping on structural and electrical properties of PVA: NaBr polymer electrolyte

NASA Astrophysics Data System (ADS)

Sagar, Rohan N.; Ravindrachary, V.; Guruswamy, B.; Hegde, Shreedatta; Mahanthesh, B. K.; Kumari, R. Padma

2018-05-01

The effect of TiO2 nanoparticles on morphology and electrical properties of PVA: NaBr composite films were carried out using various techniques. The pure and TiO2 nanoparticle doped PVA: NaBr composite films were prepared using solvent casting method. The FTIR spectral studies shows that the Ti+ ions of TiO2 interacts with hydroxyl group (OH) of PVA via hydrogen bonding and forms the charge transfer complexes (CTC). These interactions are of inter/intra molecular type and affects the surface morphology as well as the electrical properties of composite films. XRD study shows that the crystallinity of the composite increases with doping level. SEM studies shows that the increase in roughness of the surface of the composite films and uniform dispersion of nanofillers in polymer matrix. Electrical properties are analyzed using impedance analyzer and higher conductivity (10-4Scm-1) is achieved for 5 wt % TiO2 doping concentration.

Polysaccharides-based multiparticulated interpolyelectrolyte complexes for controlled benznidazole release.

PubMed

García, Mónica C; Manzo, Rubén H; Jimenez-Kairuz, Alvaro

2018-07-10

Polysaccharides-based delivery systems and interpolyelectrolyte complexes (IPECs) are interesting alternatives to control the release of drugs, thereby improving therapies. Benznidazole (BZ) is the selected drug for Chagas disease pharmacotherapy. However, its side effects limit its efficacy and safety. We developed novel multiparticulated BZ-loaded IPECs based on chitosan and alginic acid, and investigated their physicochemical and pharmacotechnical properties. IPECs were obtained using the casting solvent method, followed by wet granulation. They presented ionic interaction between the biopolymers, revealed that free BZ was uniformly distributed and showed adequate flow properties for hard gelatin-capsule formulation. The multiparticles exhibited mucoadhesion properties and revealed modulation of BZ release, depending on the release media, in accordance with the fluid uptake. The IPECs developed possess interesting properties that are promising for the design of novel alternatives to improve Chagas disease pharmacotherapy, which would diminish BZ's adverse effects and/or allow a reduction in the frequency of BZ administration. Copyright © 2018 Elsevier B.V. All rights reserved.

Structural characterization of porous low-k thin films prepared by different techniques using x-ray porosimetry

NASA Astrophysics Data System (ADS)

Lee, Hae-Jeong; Soles, Christopher L.; Liu, Da-Wei; Bauer, Barry J.; Lin, Eric K.; Wu, Wen-li; Grill, Alfred

2004-03-01

Three different types of porous low-k dielectric films, with similar dielectric constants, are characterized using x-ray porosimetry (XRP). XRP is used to extract critical structural information, such as the average density, wall density, porosity, and pore size distribution. The materials include a plasma-enhanced-chemical-vapor-deposited carbon-doped oxide film composed of Si, C, O, and H (SiCOH) and two spin cast silsesquioxane type films—methylsilsesquioxane with a polymeric porogen (porous MSQ) and hydrogensilsesquioxane with a high boiling point solvent (porous HSQ). The porous SiCOH film displays the smallest pore sizes, while porous HSQ film has both the highest density wall material and porosity. The porous MSQ film exhibits a broad range of pores with the largest average pore size. We demonstrate that the average pore size obtained by the well-established method of neutron scattering and x-ray reflectivity is in good agreement with the XRP results.

Possibility of reconstruction of dental plaster cast from 3D digital study models

PubMed Central

2013-01-01

Objectives To compare traditional plaster casts, digital models and 3D printed copies of dental plaster casts based on various criteria. To determine whether 3D printed copies obtained using open source system RepRap can replace traditional plaster casts in dental practice. To compare and contrast the qualities of two possible 3D printing options – open source system RepRap and commercially available 3D printing. Design and settings A method comparison study on 10 dental plaster casts from the Orthodontic department, Department of Stomatology, 2nd medical Faulty, Charles University Prague, Czech Republic. Material and methods Each of 10 plaster casts were scanned by inEos Blue scanner and the printed on 3D printer RepRap [10 models] and ProJet HD3000 3D printer [1 model]. Linear measurements between selected points on the dental arches of upper and lower jaws on plaster casts and its 3D copy were recorded and statistically analyzed. Results 3D printed copies have many advantages over traditional plaster casts. The precision and accuracy of the RepRap 3D printed copies of plaster casts were confirmed based on the statistical analysis. Although the commercially available 3D printing enables to print more details than the RepRap system, it is expensive and for the purpose of clinical use can be replaced by the cheaper prints obtained from RepRap printed copies. Conclusions Scanning of the traditional plaster casts to obtain a digital model offers a pragmatic approach. The scans can subsequently be used as a template to print the plaster casts as required. Using 3D printers can replace traditional plaster casts primarily due to their accuracy and price. PMID:23721330

Study of the pore structure of ceramics prepared by the slip casting method

NASA Technical Reports Server (NTRS)

Guzman, I. Y.; Dobysh, A. V.

1984-01-01

The porosity of the slip cast Si3N4 is similar to that of pressed Si3N4 formed at 2500 kg/sq cm. The porosity of cast Si oxynitride is equivalent to that of samples stressed at 10,000 kg/sq cm. Crucibles formed from these materials by slip casting have high thermal shock and corrosion resistance.

Energy Saving Melting and Revert Reduction Technology (Energy-SMARRT): Clean Steel Casting Production

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

Kuyucak, Selcuk; Li, Delin

2013-12-31

Inclusions in steel castings can cause rework, scrap, poor machining, and reduced casting performance, which can obviously result in excess energy consumption. Significant progress in understanding inclusion source, formation and control has been made. Inclusions can be defined as non-metallic materials such as refractory, sand, slag, or coatings, embedded in a metallic matrix. This research project has focused on the mold filling aspects to examine the effects of pouring methods and gating designs on the steel casting cleanliness through water modeling, computer modeling, and melting/casting experiments. Early in the research project, comprehensive studies of bottom-pouring water modeling and low-alloy steelmore » casting experiments were completed. The extent of air entrainment in bottom-poured large castings was demonstrated by water modeling. Current gating systems are designed to prevent air aspiration. However, air entrainment is equally harmful and no prevention measures are in current practice. In this study, new basin designs included a basin dam, submerged nozzle, and nozzle extension. The entrained air and inclusions from the gating system were significantly reduced using the new basin method. Near the end of the project, there has been close collaboration with Wescast Industries Inc., a company manufacturing automotive exhaust components. Both computer modeling using Magma software and melting/casting experiments on thin wall turbo-housing stainless steel castings were completed in this short period of time. Six gating designs were created, including the current gating on the pattern, non-pressurized, partially pressurized, naturally pressurized, naturally pressurized without filter, and radial choke gating without filter, for Magma modeling. The melt filling velocity and temperature were determined from the modeling. Based on the simulation results, three gating designs were chosen for further melting and casting experiments on the same casting pattern using the lip pouring method. It was observed again that gating designs greatly influenced the melt filling velocity and the number of inclusion defects. The radial choked gating showed improvements in casting cleanliness and yield over the other gatings, even though no mold filters were used in the gating system.« less

Evaluation of the marginal fit of metal copings fabricated on three different marginal designs using conventional and accelerated casting techniques: an in vitro study.

PubMed

Vaidya, Sharad; Parkash, Hari; Bhargava, Akshay; Gupta, Sharad

2014-01-01

Abundant resources and techniques have been used for complete coverage crown fabrication. Conventional investing and casting procedures for phosphate-bonded investments require a 2- to 4-h procedure before completion. Accelerated casting techniques have been used, but may not result in castings with matching marginal accuracy. The study measured the marginal gap and determined the clinical acceptability of single cast copings invested in a phosphate-bonded investment with the use of conventional and accelerated methods. One hundred and twenty cast coping samples were fabricated using conventional and accelerated methods, with three finish lines: Chamfer, shoulder and shoulder with bevel. Sixty copings were prepared with each technique. Each coping was examined with a stereomicroscope at four predetermined sites and measurements of marginal gaps were documented for each. A master chart was prepared for all the data and was analyzed using Statistical Package for the Social Sciences version. Evidence of marginal gap was then evaluated by t-test. Analysis of variance and Post-hoc analysis were used to compare two groups as well as to make comparisons between three subgroups . Measurements recorded showed no statistically significant difference between conventional and accelerated groups. Among the three marginal designs studied, shoulder with bevel showed the best marginal fit with conventional as well as accelerated casting techniques. Accelerated casting technique could be a vital alternative to the time-consuming conventional casting technique. The marginal fit between the two casting techniques showed no statistical difference.

Apparatus and method for removing solvent from carbon dioxide in resin recycling system

DOEpatents

Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

2009-01-06

A two-step resin recycling system and method solvent that produces essentially contaminant-free synthetic resin material. The system and method includes one or more solvent wash vessels to expose resin particles to a solvent, the solvent contacting the resin particles in the one or more solvent wash vessels to substantially remove contaminants on the resin particles. A separator is provided to separate the solvent from the resin particles after removal from the one or more solvent wash vessels. The resin particles are next exposed to carbon dioxide in a closed loop carbon dioxide system. The closed loop system includes a carbon dioxide vessel where the carbon dioxide is exposed to the resin, substantially removing any residual solvent remaining on the resin particles after separation. A separation vessel is also provided to separate the solvent from the solvent laden carbon dioxide. Both the carbon dioxide and the solvent are reused after separation in the separation vessel.

High Tc superconducting films from metallo-organic precursors

NASA Astrophysics Data System (ADS)

Davison, W. W.; Shyu, S. G.; Buchanan, R. C.

High Tc superconducting films of heavy metal soaps (derived from carboxylic acid precursors) have been prepared on Si and other substrates. The precursors were synthesized and mixed in appropriate molar ratios to form the high Tc compound YBa2Cu3O(7-x), using a high boiling point common solvent base. The precursor solution was deposited by a spin casting technique on the substrates. Film thicknesses of 0.1-1.0 micron were achieved after heat treatment at 550-850 C at not longer than 4 hours. Films were analyzed as to orientation, appropriate phase, interfacial reaction, and superconducting properties.

Design and Fabrication of Graphene Reinforced Polymer Conductive Patch-Based Inset Fed Microstrip Antenna

NASA Astrophysics Data System (ADS)

Deepak, A.; Kannan, P. Muthu; Shankar, P.

This work explores the design and fabrication of graphene reinforced polyvinylidene fluoride (PVDF) patch-based microstrip antenna. Primarily, antenna was designed at 6GHz frequency and simulation results were obtained using Ansoft HFSS tool. Later fabrication of antenna was carried out with graphene-PVDF films as conducting patch deposited on bakelite substrate and copper as ground plane. Graphene-PVDF films were prepared using solvent casting process. The radiation efficiency of fabricated microstrip patch antenna was 48% entailing it to be adapted as a practically functional antenna. Both simulated and the practical results were compared and analyzed.

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

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

Mehtani, Hitesh Kumar, E-mail: kkraina@gmail.com; Kumar, Rishi, E-mail: kkraina@gmail.com; Raina, K. K., E-mail: kkraina@gmail.com

2014-04-24

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 β phase was ensured in spin cast PVDF film by the FTIR spectroscopy. The β phase is very important in the application because it improve the properties like piezoelectricity by modifying PVDF crystallinity.

Macrosegregation in aluminum alloy ingot cast by the semicontinuous direct chill method

NASA Technical Reports Server (NTRS)

Yu, H.; Granger, D. A.

1984-01-01

A theoretical model of the semicontinuous DC casting method is developed to predict the positive segregation observed at the subsurface and the negative segregation commonly found at the center of large commercial-size aluminum alloy ingot. Qualitative analysis of commercial-size aluminum alloy semicontinuous cast direct chill (DC) ingot is carried out. In the analysis, both positive segregation in the ingot subsurface and negative segregation at the center of the ingot are examined. Ingot subsurface macrosegregation is investigated by considering steady state casting of a circular cross-section binary alloy ingot. Nonequilibrium solidification is assumed with no solid diffusion, constant equilibrium partition ratio, and constant solid density.

Development of an inverse heat conduction model and its application to determination of heat transfer coefficient during casting solidification

NASA Astrophysics Data System (ADS)

Zhang, Liqiang; Reilly, Carl; Li, Luoxing; Cockcroft, Steve; Yao, Lu

2014-07-01

The interfacial heat transfer coefficient (IHTC) is required for the accurate simulation of heat transfer in castings especially for near net-shape processes. The large number of factors influencing heat transfer renders quantification by theoretical means a challenge. Likewise experimental methods applied directly to temperature data collected from castings are also a challenge to interpret because of the transient nature of many casting processes. Inverse methods offer a solution and have been applied successfully to predict the IHTC in many cases. However, most inverse approaches thus far focus on use of in-mold temperature data, which may be a challenge to obtain in cases where the molds are water-cooled. Methods based on temperature data from the casting have the potential to be used however; the latent heat released during the solidification of the molten metal complicates the associated IHTC calculations. Furthermore, there are limits on the maximum distance the thermocouples can be placed from the interface under analysis. An inverse conduction based method have been developed, verified and applied successfully to temperature data collected from within an aluminum casting in proximity to the mold. A modified specific heat method was used to account for latent heat evolution in which the rate of change of fraction solid with temperature was held constant. An analysis conducted with the inverse model suggests that the thermocouples must be placed no more than 2 mm from the interface. The IHTC values calculated for an aluminum alloy casting were shown to vary from 1,200 to 6,200 Wm-2 K-1. Additionally, the characteristics of the time-varying IHTC have also been discussed.

Process for preparing essentially colorless polyimide film containing phenoxy-linked diamines

NASA Technical Reports Server (NTRS)

Stclair, A. K.; Stclair, T. L.

1986-01-01

A polyimide film that is approximately 90% transparent at 500 nm, useful for thermal protective coatings and solar cells, and the processes for preparing the same by thermal and chemical conversion are disclosed. An essential feature for achieving maximum optical transparency films requires utilizing recrystallized and/or sublimated specific aromatic diamines and dianhydride monomers and introducing phenoxy or thiophenyl separator groups and isomeric m,m' or o,p'-oriented diamines into the polymer molecular structure. The incorporation of these groups in the polymer structure serves to separate the chromaphoric centers and reduce the formation of inter-chain and intra-chain charge transfer complexes which normally cause absorptions in the UV-visible range. The films may be obtained by hand, brushing, casting, or spraying a layer of polyamic acid solutions onto a surface and thermally converting the applied layer to the polyimide, or the polyamic acid solution can be chemically converted to the polyimide, subsequentially dissolved in an organic solvent, and applied as a polyimide film layer with the solvent therein thermally removed.

Computing pKa Values in Different Solvents by Electrostatic Transformation.

PubMed

Rossini, Emanuele; Netz, Roland R; Knapp, Ernst-Walter

2016-07-12

We introduce a method that requires only moderate computational effort to compute pKa values of small molecules in different solvents with an average accuracy of better than 0.7 pH units. With a known pKa value in one solvent, the electrostatic transform method computes the pKa value in any other solvent if the proton solvation energy is known in both considered solvents. To apply the electrostatic transform method to a molecule, the electrostatic solvation energies of the protonated and deprotonated molecular species are computed in the two considered solvents using a dielectric continuum to describe the solvent. This is demonstrated for 30 molecules belonging to 10 different molecular families by considering 77 measured pKa values in 4 different solvents: water, acetonitrile, dimethyl sulfoxide, and methanol. The electrostatic transform method can be applied to any other solvent if the proton solvation energy is known. It is exclusively based on physicochemical principles, not using any empirical fetch factors or explicit solvent molecules, to obtain agreement with measured pKa values and is therefore ready to be generalized to other solute molecules and solvents. From the computed pKa values, we obtained relative proton solvation energies, which agree very well with the proton solvation energies computed recently by ab initio methods, and used these energies in the present study.

Control and characterization of textured, hydrophobic ionomer surfaces

NASA Astrophysics Data System (ADS)

Wang, Xueyuan

Polymer thin films are of increasing interest in many industrial and technological applications. Superhydrophobic, self-cleaning surfaces have attracted a lot of attention for their application in self-cleaning, anti-sticking coatings, stain resistance, or anti-contamination surfaces in diverse technologies, including medical, transportation, textiles, electronics and paints. This thesis focuses on the preparation of nanometer to micrometer-size particle textured surfaces which are desirable for super water repellency. Textured surfaces consisting of nanometer to micrometer-sized lightly sulfonated polystyrene ionomer (SPS) particles were prepared by rapid evaporation of the solvent from a dilute polymer solution cast onto silica. The effect of the solvent used to spin coat the film, the molecular weight of the ionomer, and the rate of solvent evaporation were investigated. The nano-particle or micron-particle textured ionomer surfaces were prepared by either spin coating or solution casting ionomer solutions at controlled evaporation rates. The surface morphologies were consistent with a spinodal decomposition mechanism where the surface first existed as a percolated-like structure and then ripened into droplets if molecular mobility was retained for sufficient time. The SPS particles or particle aggregates were robust and resisted deformation even after annealing at 120°C for one week. The water contact angles on as-prepared surfaces were relatively low, ~ 90° since the polar groups in ionomer reduce the surface hydrophobicity. After chemical vapor deposition of 1H,1H,2H,2H-perfluorooctyltrichlorosilane, the surface contact angles increased to ~ 109° on smooth surfaces and ~140° on the textured surfaces. Water droplets stuck to these surfaces even when tilted 90 degrees. Superhydrophobic surfaces were prepared by spraying coating ionomer solutions and Chemical Vapor Deposition (CVD) of 1H,1H,2H,2H-perfluorooctyltrichlorosilane onto textured surfaces. The surfaces after CVD of silane exhibited water contact angle of 152° and the water droplet stuck to the surfaces without falling even when tilted upside down. This kind of sticky superhydrophobic surface would have potential applications in no-loss transport of liquid, and cleaning robots.

ToxCast: Developing Predictive Signatures of Chemically Induced Toxicity (Developing Predictive Bioactivity Signatures from ToxCasts HTS Data)

EPA Science Inventory

ToxCast, the United States Environmental Protection Agency’s chemical prioritization research program, is developing methods for utilizing computational chemistry, bioactivity profiling and toxicogenomic data to predict potential for toxicity and prioritize limited testing resour...

Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

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

Russell, Steven, W.; Lundin, Carl, W.

2005-09-30

The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing proceduresmore » for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope® and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope® were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought DSS and tested per ASTM A923 method B (Charpy impact test). Method A (sodium hydroxide etch test) was performed on one half of a fractured Charpy V-notch impact sample and Method C (ferric chloride corrosion weight loss test) was performed on another half. Test results for the three cast lots and one wrought lot indicate that ASTM A923 is relevant for detecting intermetallic phases in cast DSS. In the ASTM A923 round robin study, five laboratories conducted ASTM A923 Methods A & C on cast DSS material and the lab-to-lab reproducibility of the data was determined. Two groups of samples were sent to the participants. Group 1 samples were tested per ASTM A923 Method A, group 2 samples were tested by ASTM A923 Method C. Testing procedures for this round robin study were identical to those used in the ASTM A923 applicability study. Results from this round robin indicate that there is excellent lab-to-lab reproducibility of ASTM A923 with respect to cast DSS and that ASTM A923 could be expanded to cover both wrought and cast DSS. In the ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases, Ten heats of ASTM A890-4A (CD3MN) in the foundry solution annealed condition were tested per ASTM A923 Methods A, B, & C. Testing of these materials per ASTM A923 was used to determine if the foundry solution anneal procedures were adequate to completely eliminate any intermetallic phases, which may have precipitated during the casting and subsequent heat treatment processes. All heats showed no sign of intermetallic phase per Method A, passed minimum Charpy impact energy requirements per Method B (> 40 ft-lbs @ -40°C (-40°F)), and showed negligible weight loss per Method C (< 10 mdd). These results indicate that the solution annealing procedure used by foundries is adequate to produce a product free from intermetallic phases.« less

Final Report, Volume 2, The Development of Qualification Standards for Cast Duplex Stainless Steel

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

Russell, Steven, W.; Lundin, Carl, D.

2005-09-30

The scope of testing cast Duplex Stainless Steel (DSS) required testing to several ASTM specifications, while formulating and conducting industry round robin tests to verify and study the reproducibility of the results. ASTM E562 (Standard Test Method for Determining Volume Fraction by Systematic manual Point Count) and ASTM A923 (Standard Test Methods for Detecting Detrimental Intermetallic Phase in Wrought Duplex Austenitic/Ferritic Stainless Steels) were the specifications utilized in conducting this work. An ASTM E562 industry round robin, ASTM A923 applicability study, ASTM A923 industry round robin, and an ASTM A923 study of the effectiveness of existing foundry solution annealing proceduresmore » for producing cast DSS without intermetallic phases were implemented. In the ASTM E562 study, 5 samples were extracted from various cast austenitic and DSS in order to have varying amounts of ferrite. Each sample was metallographically prepared by UT and sent to each of 8 participants for volume fraction of ferrite measurements. Volume fraction of ferrite was measured using manual point count per ASTM E562. FN was measured from the Feritescope{reg_sign} and converted to volume fraction of ferrite. Results indicate that ASTM E562 is applicable to DSS and the results have excellent lab-to-lab reproducibility. Also, volume fraction of ferrite conversions from the FN measured by the Feritescope{reg_sign} were similar to volume fraction of ferrite measured per ASTM E562. In the ASTM A923 applicability to cast DSS study, 8 different heat treatments were performed on 3 lots of ASTM A890-4A (CD3MN) castings and 1 lot of 2205 wrought DSS. The heat treatments were selected to produce a wide range of cooling rates and hold times in order to study the suitability of ASTM A923 to the response of varying amounts on intermetallic phases [117]. The test parameters were identical to those used to develop ASTM A923 for wrought DSS. Charpy V-notch impact samples were extracted from the castings and wrought DSS and tested per ASTM A923 method B (Charpy impact test). Method A (sodium hydroxide etch test) was performed on one half of a fractured Charpy V-notch impact sample and Method C (ferric chloride corrosion weight loss test) was performed on another half. Test results for the three cast lots and one wrought lot indicate that ASTM A923 is relevant for detecting intermetallic phases in cast DSS. In the ASTM A923 round robin study, five laboratories conducted ASTM A923 Methods A & C on cast DSS material and the lab-to-lab reproducibility of the data was determined. Two groups of samples were sent to the participants. Group 1 samples were tested per ASTM A923 Method A, group 2 samples were tested by ASTM A923 Method C. Testing procedures for this round robin study were identical to those used in the ASTM A923 applicability study. Results from this round robin indicate that there is excellent lab-to-lab reproducibility of ASTM A923 with respect to cast DSS and that ASTM A923 could be expanded to cover both wrought and cast DSS. In the ASTM A923 study of the effectiveness of existing foundry solution annealing procedures for producing cast DSS without intermetallic phases, Ten heats of ASTM A890-4A (CD3MN) in the foundry solution annealed condition were tested per ASTM A923 Methods A, B, & C. Testing of these materials per ASTM A923 was used to determine if the foundry solution anneal procedures were adequate to completely eliminate any intermetallic phases, which may have precipitated during the casting and subsequent heat treatment processes. All heats showed no sign of intermetallic phase per Method A, passed minimum Charpy impact energy requirements per Method B (> 40 ft-lbs {at} -40 C (-40 F)), and showed negligible weight loss per Method C (< 10 mdd). These results indicate that the solution annealing procedure used by foundries is adequate to produce a product free from intermetallic phases.« less

Development and validation of a fast static headspace GC method for determination of residual solvents in permethrin.

PubMed

Tian, Jingzhi; Rustum, Abu

2016-09-05

A fast static headspace gas chromatography (HS-GC) method was developed to separate all residual solvents present in commercial active pharmaceutical ingredient (API) batches of permethrin. A total of six residual solvents namely 2-methylpentane, 3-methylpentane, methylcyclopentane, n-hexane, cyclohexane and toluene were found in typical commercial batches of permethrin; and three of them are not in the list of ICH solvents. All six residual solvents were baseline separated in five minutes by the new method presented in this paper. The method was successfully validated as per International Conference on Harmonisation (ICH) guidelines. Evaluation of this method was conducted to separate 26 commonly used solvents in the manufacturing of various APIs, key intermediates of APIs and pharmaceutical excipients. The results of the evaluation demonstrated that this method can also be used as a general method to determine residual solvents in various APIs, intermediates and excipients that are used in pharmaceutical products. Copyright © 2016 Elsevier B.V. All rights reserved.

Prosthetic misfit of implant-supported prosthesis obtained by an alternative section method

PubMed Central

Falcão-Filho, Hilmo Barreto Leite; de Aguiar, Fábio Afrânio; Rodrigues, Renata Cristina Silveira; de Mattos, Maria da Gloria Chiarello; Ribeiro, Ricardo Faria

2012-01-01

PURPOSE Adequate passive-fitting of one-piece cast 3-element implant-supported frameworks is hard to achieve. This short communication aims to present an alternative method for section of one-piece cast frameworks and for casting implant-supported frameworks. MATERIALS AND METHODS Three-unit implant-supported nickel-chromium (Ni-Cr) frameworks were tested for vertical misfit (n = 6). The frameworks were cast as one-piece (Group A) and later transversally sectioned through a diagonal axis (Group B) and compared to frameworks that were cast diagonally separated (Group C). All separated frameworks were laser welded. Only one side of the frameworks was screwed. RESULTS The results on the tightened side were significantly lower in Group C (6.43 ± 3.24 µm) when compared to Groups A (16.50 ± 7.55 µm) and B (16.27 ± 1.71 µm) (P<.05). On the opposite side, the diagonal section of the one-piece castings for laser welding showed significant improvement in the levels of misfit of the frameworks (Group A, 58.66±14.30 µm; Group B, 39.48±12.03 µm; Group C, 23.13±8.24 µm) (P<.05). CONCLUSION Casting diagonally sectioned frameworks lowers the misfit levels. Lower misfit levels for the frameworks can be achieved by diagonally sectioning one-piece frameworks. PMID:22737313

Methods for recovering a polar solvent from a fluid stream contaminated with at least one polar impurity

DOEpatents

Ginosar, Daniel M.; Wendt, Daniel S.

2012-11-13

A method of removing a polar solvent from a fluid volume contaminated with at least one polar impurity, such as a free fatty acid, is provided. The method comprises providing a fluid volume that includes at least one polar impurity dissolved in at least one solvent. The fluid volume is contacted with an expanding gas to remove the at least one solvent. The expanding gas may be dissolved into the at least one solvent in the fluid volume to form a gas-expanded solvent. The immiscibility of the polar impurities in the gas-expanded solvent enables separation of the polar impurities from the gas-expanded solvent. After separation of the polar impurities, at least one of the temperature and pressure may be reduced to separate the solvent from the expanding gas such that the clean solvent may be reused.

Numerical Treatment of Stokes Solvent Flow and Solute-Solvent Interfacial Dynamics for Nonpolar Molecules.

PubMed

Sun, Hui; Zhou, Shenggao; Moore, David K; Cheng, Li-Tien; Li, Bo

2016-05-01

We design and implement numerical methods for the incompressible Stokes solvent flow and solute-solvent interface motion for nonpolar molecules in aqueous solvent. The balance of viscous force, surface tension, and van der Waals type dispersive force leads to a traction boundary condition on the solute-solvent interface. To allow the change of solute volume, we design special numerical boundary conditions on the boundary of a computational domain through a consistency condition. We use a finite difference ghost fluid scheme to discretize the Stokes equation with such boundary conditions. The method is tested to have a second-order accuracy. We combine this ghost fluid method with the level-set method to simulate the motion of the solute-solvent interface that is governed by the solvent fluid velocity. Numerical examples show that our method can predict accurately the blow up time for a test example of curvature flow and reproduce the polymodal (e.g., dry and wet) states of hydration of some simple model molecular systems.

Numerical Treatment of Stokes Solvent Flow and Solute-Solvent Interfacial Dynamics for Nonpolar Molecules

PubMed Central

Sun, Hui; Zhou, Shenggao; Moore, David K.; Cheng, Li-Tien; Li, Bo

2015-01-01

We design and implement numerical methods for the incompressible Stokes solvent flow and solute-solvent interface motion for nonpolar molecules in aqueous solvent. The balance of viscous force, surface tension, and van der Waals type dispersive force leads to a traction boundary condition on the solute-solvent interface. To allow the change of solute volume, we design special numerical boundary conditions on the boundary of a computational domain through a consistency condition. We use a finite difference ghost fluid scheme to discretize the Stokes equation with such boundary conditions. The method is tested to have a second-order accuracy. We combine this ghost fluid method with the level-set method to simulate the motion of the solute-solvent interface that is governed by the solvent fluid velocity. Numerical examples show that our method can predict accurately the blow up time for a test example of curvature flow and reproduce the polymodal (e.g., dry and wet) states of hydration of some simple model molecular systems. PMID:27365866

SLIP CASTING METHOD

DOEpatents

Allison, A.G.

1959-09-01

S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

Photoresponsive molecularly imprinted hydrogel casting membrane for the determination of trace tetracycline in milk.

PubMed

Wang, Qiang; Lv, Zhen; Tang, Qian; Gong, Cheng-Bin; Lam, Michael Hon Wah; Ma, Xue-Bing; Chow, Cheuk-Fai

2016-03-01

This study aimed to develop a photoresponsive molecularly imprinted hydrogel (MIH) casting membrane for the determination of trace tetracycline (TC) in milk. This MIH casting membrane combined the specificity of MIHs, the photoresponsive properties of azobenzene, and the portable properties of a membrane. Photoresponsive TC-imprinted MIHs were initially fabricated and then cast on sodium dodecyl sulfonate polyacrylamide gel. After TC removal, a photoresponsive MIH casting membrane was obtained. The photoresponsive properties of the MIH casting membrane were robust, and no obvious photodegradation was observed after 20 cycles. The MIH casting membrane displayed specific affinity to TC upon alternate irradiation at 365 and 440 nm; it could quantitatively uptake and release TC. The TC concentration (0.0-2.0 × 10(-4) mol l(-1)) in aqueous solution displayed a linear relationship with the photoisomerization rate constant of azobenzene within the MIH casting membrane. As such, a quick detection method for trace TC in aqueous foodstuff samples was established. The recovery of this method for TC in milk was investigated with a simple pretreatment of milk, and a high recovery of 100.54-106.35% was obtained. Therefore, the fabricated membrane can be used as a portable molecular sensor that can be easily recycled. Copyright © 2015 John Wiley & Sons, Ltd.

Modification of cellulose acetate nanocomposite with TiO{sub 2}-organoclay as nanofiller and its self-photodegradation study

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

Luthfiyah, Siti Zahrotul; Krisnandi, Yuni K., E-mail: yuni.krisnandi@sci.ui.ac.id; Andhika, Kadek

2016-04-19

Nanocomposite cellulose acetate has been synthesized using organoclay nanofiller modified with TiO{sub 2}. Tapanuli bentonite was previously subjected to purification and sodium exchangeprocesses, then modified with TiO{sub 2},that was added as much as 0%, 1%, 3%, 5%, and 10% weight of the total composite. FTIR analysis showed intercalation with Hexadecyl Ammonium Bromide (HDTMABr) surfactant was successfully carried out, indicated by new absorption bands at 2636 cm{sup −1} and 2569 cm{sup −1}. XRD diffractogram shows the increase in basal spasing on the modification of bentonite from 15.7 Å to 19.7 Å after modification. Fabrication of nanocomposite film was carried out using acetone asmore » solvent and through solvent casting method. Nanocomposite application in photodegradation test was carried out under direct sunlight irradiation, UV light, and without irradiation for six days. It is found that the greater the amount of TiO{sub 2} in the composites, the more weight loss occured, due to photodegredation. Percent weight loss in the UV light irradiation are 1.11%, 2.15%, 2.73%, 3.18%, and 3.96%, while under direct sunlight irradiation, the weight loss was 1.03%, 3.03%, 3.88%, 4.53%, and 5.57%. Modification of nanocomposite with the addition of photocatalytic TiO{sub 2} has shown to give the nanocomposite the ability of self-photodegradation.« less

Conformation Effects on the Photoluminescence Behavior of Anchored MEH-PPV Pancakes and Brushes

NASA Astrophysics Data System (ADS)

Shih, Kuo Sheng; Chen, Po-Tsun; Yang, Arnold C.-M.

2012-02-01

Single molecular layer of poly[2-methoxy-5-(2'-ethylhexyl)oxy)-1,4- phenylenevinylene] (MEH-PPV) grafted on primed silicon wafer were synthesized, forming brushes (chain spacing 0.54 nm via graft-from) or pancakes (˜ 7nm to 34 nm via graft-to). For the tight-packed brushes, the PL emission peak, residing in the range from 434 nm to 550 nm depending on the chain length, was generally unchanged when transferring between the dry and solvent immersion states. However, for the pancakes, the emission peak blue-shifted dramatically (up to 100 nm) when dried in the air relative to that in the solvent. These shifts were fully reversible in the dry-wet cycles. The large blue shifts of the anchored pancakes were attributed to the mechanical stretching of entangled MEH-PPV segments in contact with substrate upon solvent loss. In contrast, the blue shifts disappeared and small red shifts emerged instead for extremely slowly drying (24 hrs drying time), revealing the stress-relaxation pathways in the equilibrium conditions. The drying-induced blue shift was also observed in the un-anchored drop-casting samples but the reversibility vanished. Finally, a large enhancement of PL intensity was accompanied with the blue shifts, manifesting the effect of the molecular constraints.

Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C61-butyric acid methyl ester

NASA Astrophysics Data System (ADS)

Lazzerini, Giovanni Mattia; Paternò, Giuseppe Maria; Tregnago, Giulia; Treat, Neil; Stingelin, Natalie; Yacoot, Andrew; Cacialli, Franco

2016-02-01

We report high-resolution, traceable atomic force microscopy measurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crystals' height. The optical interferometer together with the stabilized laser provides traceability (via the laser wavelength) of the vertical measurements made with the atomic force microscope. We find that the crystals can conform to the surface topography, thanks to their height being significantly smaller compared to their lateral dimensions (namely, heights between about 50 nm and 140 nm, for the crystals analysed, vs. several tens of microns lateral dimensions). The vast majority of the crystals are flat, but an isolated, non-flat crystal provides insights into the growth mechanism and allows identification of "molecular terraces" whose height corresponds to one of the lattice constants of the single PCBM crystal (1.4 nm) as measured with X-ray diffraction.

Traceable atomic force microscopy of high-quality solvent-free crystals of [6,6]-phenyl-C{sub 61}-butyric acid methyl ester

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

Lazzerini, Giovanni Mattia; Yacoot, Andrew; Paternò, Giuseppe Maria

2016-02-01

We report high-resolution, traceable atomic force microscopy measurements of high-quality, solvent-free single crystals of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). These were grown by drop-casting PCBM solutions onto the spectrosil substrates and by removing the residual solvent in a vacuum. A home-built atomic force microscope featuring a plane mirror differential optical interferometer, fiber-fed from a frequency-stabilized laser (emitting at 632.8 nm), was used to measure the crystals' height. The optical interferometer together with the stabilized laser provides traceability (via the laser wavelength) of the vertical measurements made with the atomic force microscope. We find that the crystals can conform to the surfacemore » topography, thanks to their height being significantly smaller compared to their lateral dimensions (namely, heights between about 50 nm and 140 nm, for the crystals analysed, vs. several tens of microns lateral dimensions). The vast majority of the crystals are flat, but an isolated, non-flat crystal provides insights into the growth mechanism and allows identification of “molecular terraces” whose height corresponds to one of the lattice constants of the single PCBM crystal (1.4 nm) as measured with X-ray diffraction.« less

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

NASA Technical Reports Server (NTRS)

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

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.

Single underwater image enhancement based on color cast removal and visibility restoration

NASA Astrophysics Data System (ADS)

Li, Chongyi; Guo, Jichang; Wang, Bo; Cong, Runmin; Zhang, Yan; Wang, Jian

2016-05-01

Images taken under underwater condition usually have color cast and serious loss of contrast and visibility. Degraded underwater images are inconvenient for observation and analysis. In order to address these problems, an underwater image-enhancement method is proposed. A simple yet effective underwater image color cast removal algorithm is first presented based on the optimization theory. Then, based on the minimum information loss principle and inherent relationship of medium transmission maps of three color channels in an underwater image, an effective visibility restoration algorithm is proposed to recover visibility, contrast, and natural appearance of degraded underwater images. To evaluate the performance of the proposed method, qualitative comparison, quantitative comparison, and color accuracy test are conducted. Experimental results demonstrate that the proposed method can effectively remove color cast, improve contrast and visibility, and recover natural appearance of degraded underwater images. Additionally, the proposed method is comparable to and even better than several state-of-the-art methods.

System and method for treatment of a flue gas

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

Spiry, Irina Pavlovna; Wood, Benjamin Rue; Singh, Surinder Prabhjot

A method for treatment of a flue gas involves feeding the flue gas and a lean solvent to an absorber. The method further involves reacting the flue gas with the lean solvent within the absorber to generate a clean flue gas and a rich solvent. The method also involves feeding the clean flue gas from the absorber and water from a source, to a wash tower to separate a stripped portion of the lean solvent from the clean flue gas to generate a washed clean flue gas and a mixture of the water and the stripped portion of the leanmore » solvent. The method further involves treating at least a portion of the mixture of the water and the stripped portion of the lean solvent via a separation system to separate the water from the stripped portion of the lean solvent.« less

[Variables effecting casting accuracy of quick heating casting investments].

PubMed

Takahashi, H; Nakamura, H; Iwasaki, N; Morita, N; Habu, N; Nishimura, F

1994-06-01

Recently, several new products of investments for "quick heating" have been put on the Japanese market. The total casting procedure time for this quick heating method involves only one hour; 30-minutes waiting after the start of mixing before placing the mold directly into the 700 degrees C furnace and 30-minutes heating in the furnace. The purpose of this study was to evaluate two variables effecting casting accuracy using these new investments. The effect of thickness of the casting liner inside the casting ring and the effect of waiting time before placing the mold into the 700 degrees C furnace were evaluated. A stainless-steel die with a convergence angle of 8 degrees was employed. Marginal discrepancies of the crown between the wax patterns and castings were measured. The size of the cast crown became larger when the thickness of the ring liner was thick and when the waiting time before placing the mold into the furnace was long. These results suggest that these new investments have the advantage of providing sound castings using short-time casting procedures. However, it is necessary to pay careful attention to the casting conditions for obtaining reproducible castings.

Species-Specific Predictive Signatures of Developmental Toxicity Using the ToxCast Chemical Library

EPA Science Inventory

EPA’s ToxCastTM project is profiling the in vitro bioactivity of chemicals to generate predictive signatures that correlate with observed in vivo toxicity. In vitro profiling methods from ToxCast data consist of over 600 high-throughput screening (HTS) and high-content screening ...

Operational Determination of Physical and Mechanical Properties of Cast Samples of High-Strength Iron by Means of a Magnetic-Mechanical Method

NASA Astrophysics Data System (ADS)

Slyusarev, Yu. K.; Braga, A. V.; Slyusarev, I. Yu.

2017-09-01

The effect of the chemical composition of high-strength cast iron VCh35 on the content, shape and diameter of graphite inclusions and on the presence of structurally-free cementite and defects is studied. A relationship is determined between the structure and metallurgical defects and characteristics of the mechanical and magnetic rigidity of cast samples. Relationships are established in a group of factors and property characteristics: chemical composition - microstructure - mechanical rigidity - magnetic stiffness. The basis of a method is established making it possible to perform operative non-destructive monitoring of the melt quality preparation for high-strength iron casting.

Investigation of drug release and matrix degradation of electrospun poly(DL-lactide) fibers with paracetanol inoculation.

PubMed

Cui, Wenguo; Li, Xiaohong; Zhu, Xinli; Yu, Guo; Zhou, Shaobing; Weng, Jie

2006-05-01

This study was aimed at assessing the potential use of electrospun fibers as drug delivery vehicles with focus on the different diameters and drug contents to control drug release and polymer fiber degradation. A drug-loaded solvent-casting polymer film was made with an average thickness of 100 microm for comparative purposes. DSC analysis indicated that electrospun fibers had a lower T(g) but higher transition enthalpy than solvent-casting polymer film due to the inner stress and high degree of alignment and orientation of polymer chains caused by the electrospinning process. Inoculation of paracetanol led to a further slight decrease in the T(g) and transition enthalpy. An in vitro drug release study showed that a pronounced burst release or steady release phase was initially observed followed by a plateau or gradual release during the rest time. Fibers with a larger diameter exhibited a longer period of nearly zero order release, and higher drug encapsulation led to a more significant burst release after incubation. In vitro degradation showed that the smaller diameter and higher drug entrapment led to more significant changes of morphologies. The electrospun fiber mat showed almost no molecular weight reduction, but mass loss was observed for fibers with small and medium size, which was characterized with surface erosion and inconsistent with the ordinarily polymer degrading form. Further wetting behavior analysis showed that the high water repellent property of electrospun fibers led to much slower water penetration into the fiber mat, which may contribute to the degradation profiles of surface erosion. The specific degradation profile and adjustable drug release behaviors by variation of fiber characteristics made the electrospun nonwoven mat a potential drug delivery system rather than polymer films and particles.

Photoprecursor Approach Enables Preparation of Well-Performing Bulk-Heterojunction Layers Comprising a Highly Aggregating Molecular Semiconductor.

PubMed

Suzuki, Mitsuharu; Yamaguchi, Yuji; Takahashi, Kohei; Takahira, Katsuya; Koganezawa, Tomoyuki; Masuo, Sadahiro; Nakayama, Ken-ichi; Yamada, Hiroko

2016-04-06

Active-layer morphology critically affects the performance of organic photovoltaic cells, and thus its optimization is a key toward the achievement of high-efficiency devices. However, the optimization of active-layer morphology is sometimes challenging because of the intrinsic properties of materials such as strong self-aggregating nature or low miscibility. This study postulates that the "photoprecursor approach" can serve as an effective means to prepare well-performing bulk-heterojunction (BHJ) layers containing highly aggregating molecular semiconductors. In the photoprecursor approach, a photoreactive precursor compound is solution-deposited and then converted in situ to a semiconducting material. This study employs 2,6-di(2-thienyl)anthracene (DTA) and [6,6]-phenyl-C71-butyric acid methyl ester as p- and n-type materials, respectively, in which DTA is generated by the photoprecursor approach from the corresponding α-diketone-type derivative DTADK. When only chloroform is used as a cast solvent, the photovoltaic performance of the resulting BHJ films is severely limited because of unfavorable film morphology. The addition of a high-boiling-point cosolvent, o-dichlorobenzene (o-DCB), to the cast solution leads to significant improvement such that the resulting active layers afford up to approximately 5 times higher power conversion efficiencies. The film structure is investigated by two-dimensional grazing-incident wide-angle X-ray diffraction, atomic force microscopy, and fluorescence microspectroscopy to demonstrate that the use of o-DCB leads to improvement in film crystallinity and increase in charge-carrier generation efficiency. The change in film structure is assumed to originate from dynamic molecular motion enabled by the existence of solvent during the in situ photoreaction. The unique features of the photoprecursor approach will be beneficial in extending the material and processing scopes for the development of organic thin-film devices.

Continuous manufacturing and analytical characterization of fixed-dose, multilayer orodispersible films.

PubMed

Thabet, Yasmin; Lunter, Dominique; Breitkreutz, Joerg

2018-05-30

Various drug therapies require more than one active pharmaceutical ingredient (API) for an effective treatment. There are many advantages, e.g. to improve the compliance or pharmacodynamic response in comparison to a monotherapy or to increase the therapy safety. Until now, there are only a few products available for the paediatric population due to the lack of age appropriate dosage forms or studies proving the efficacy and safety of these products. This study aims to develop orodispersible films (ODFs) in a continuous solvent casting process as child appropriate dosage form containing both enalapril maleate (EM) and hydrochlorothiazide (HCT) separated in different film layers. Furthermore, they should be characterised and the API migration analysed by confocal Raman microscopy (CRM). ODFs were successfully produced in a continuous manufacturing process in form of double- and triple-layer formulations based on hydroxypropylcellulose (HPC) or a combination of HPC and polyvinyl alcohol (PVA). CRM revealed that both APIs migrate within the film layers shortly after manufacturing. PVA inhibits the migration inside the double-layer film, but is not able to prevent the API migration as an interlayer inside a triple-layer ODF. With increasing film layers, the content of residual solvents and the disintegration time increases (mono-layer films: <10 s, triple-layer films: 37 s). In conclusion, it was feasible to produce fixed-dose combinations in therapeutic doses up to 9 mg HCT and 3.5 mg EM for the double-layer film with adequate mechanical properties, which enable coiling up onto jumbo rolls directly after production. The best separation of the two APIs was achieved by casting a double-layer ODF consisting of different film forming polymers, which can be beneficial when processing two incompatible APIs. Copyright © 2018 Elsevier B.V. All rights reserved.

Electrospun Polymer Blend Nanofibers for Tunable Drug Delivery: The Role of Transformative Phase Separation on Controlling the Release Rate.

PubMed

Tipduangta, Pratchaya; Belton, Peter; Fábián, László; Wang, Li Ying; Tang, Huiru; Eddleston, Mark; Qi, Sheng

2016-01-04

Electrospun fibrous materials have a wide range of biomedical applications, many of them involving the use of polymers as matrices for incorporation of therapeutic agents. The use of polymer blends improves the tuneability of the physicochemical and mechanical properties of the drug loaded fibers. This also benefits the development of controlled drug release formulations, for which the release rate can be modified by altering the ratio of the polymers in the blend. However, to realize these benefits, a clear understanding of the phase behavior of the processed polymer blend is essential. This study reports an in depth investigation of the impact of the electrospinning process on the phase separation of a model partially miscible polymer blend, PVP K90 and HPMCAS, in comparison to other conventional solvent evaporation based processes including film casting and spin coating. The nanoscale stretching and ultrafast solvent removal of electrospinning lead to an enhanced apparent miscibility between the polymers, with the same blends showing micronscale phase separation when processed using film casting and spin coating. Nanoscale phase separation in electrospun blend fibers was confirmed in the dry state. Rapid, layered, macroscale phase separation of the two polymers occurred during the wetting of the fibers. This led to a biphasic drug release profile from the fibers, with a burst release from PVP-rich phases and a slower, more continuous release from HPMCAS-rich phases. It was noted that the model drug, paracetamol, had more favorable partitioning into the PVP-rich phase, which is likely to be a result of greater hydrogen bonding between PVP and paracetamol. This led to higher drug contents in the PVP-rich phases than the HPMCAS-rich phases. By alternating the proportions of the PVP and HPMCAS, the drug release rate can be modulated.

Utilization of Network-Forming Block Copolymers and Ionomers in the Development of Novel Nanostructures and Responsive Media

NASA Astrophysics Data System (ADS)

Mineart, Kenneth

Network forming block copolymers, i.e. thermoplastic elastomers (TPEs), are one of the highest commodity forms of block copolymers due to their competitive elasticity and extendability as well as their ability to be melt and solution processed. TPEs owe many of their advantages to a combination of hard and soft blocks. The soft blocks, which must be covalently bound at both ends to hard blocks, connect adjacent hard domains resulting in physically cross-linked systems. Herein, simulations and theory are used to provide a molecular-level depiction of the evolution from diblock copolymers, which do not contain the ability to form physical cross-links, to network forming triblock copolymers. In addition, systems with high interblock incompatibility that are within the diblock-to-triblock transition (i.e. having high molecular asymmetry) are identified to form three component (ABC triblock copolymer) phases from copolymer containing only two chemically distinct blocks. Following this work, which emphasizes the fundamental principle of TPEs, the dissertation shifts focus to physically- and chemically-modified triblock and pentablock copolymer TPEs. Recent progress has sought to broaden TPEs to include properties that are above and beyond their inherent mechanical benefits, including responsiveness to external stimuli. The first examples presented here consist of TPEs prepared in combination with amorphous hydrocarbon additives to yield TPE gels (TPEGs). The resulting TPEGs, which maintain the beneficial processing properties of TPEs, are subsequently molded into 1- and 2-D arrays of microchannels that are filled with liquid metal. The final devices exhibit strain-sensitive electrical conductivity to at least 600% strain, have tunable compliance (ease of stretching), and are fully recyclable. The substitution of the amorphous hydrocarbon component for crystalline analogues with melting points <100 °C yield TPE composites (TPECs). The TPECs gain the added capability of thermally-triggered shape-memory actuation, which results in a number of design possibilities including: (i) multiple-transition shape-memory in single a composite, (ii) complex actuation in laminates and, (iii) thermally-responsive electrical conductivity in microchannel-molded composites filled with liquid metal. These shape-memory TPECs can also be tuned to have different shape-memory response rates through the addition of an amorphous hydrocarbon tackifier, which serves to dilute the crystalline content without altering TPE concentration. The second set of functionalized TPEs examined are midblock-sulfonated block copolymers, which have substantial ion and water transport abilities, but are often restricted in thermal processability. The casting solvent-dependent morphology of a midblock sulfonated pentablock copolymer highlights the impact of solvent templating on resulting film domain structures. It is shown that film deposition from a miscible mixture of toluene and isopropanol (TIPA) leads to spherical sulfonated domains within a nonpolar matrix whereas deposition from neat tetrahydrofuran (THF) produces a combination of lamellar and hexagonally-pack cylinder nanostructures. These morphologies can both be converted to the anticipated equilibrium morphology, alternating lamellae, using THF vapor-annealing. Further, the morphology resulting from each solvent-casting approach impacts the rate and overall capacity at which films absorb water. Specifically, THF-cast copolymers swell faster and to a greater extent. However, some intrigue lies in the transformation of the TIPA-cast copolymer upon swelling, which yields disordered, but continuous, hydrophilic domains. The disordered morphology outperforms ordered analogues in solar simulation experiments indicating higher ion conductivity.

Applying network analysis and Nebula (neighbor-edges based and unbiased leverage algorithm) to ToxCast data.

PubMed

Ye, Hao; Luo, Heng; Ng, Hui Wen; Meehan, Joe; Ge, Weigong; Tong, Weida; Hong, Huixiao

2016-01-01

ToxCast data have been used to develop models for predicting in vivo toxicity. To predict the in vivo toxicity of a new chemical using a ToxCast data based model, its ToxCast bioactivity data are needed but not normally available. The capability of predicting ToxCast bioactivity data is necessary to fully utilize ToxCast data in the risk assessment of chemicals. We aimed to understand and elucidate the relationships between the chemicals and bioactivity data of the assays in ToxCast and to develop a network analysis based method for predicting ToxCast bioactivity data. We conducted modularity analysis on a quantitative network constructed from ToxCast data to explore the relationships between the assays and chemicals. We further developed Nebula (neighbor-edges based and unbiased leverage algorithm) for predicting ToxCast bioactivity data. Modularity analysis on the network constructed from ToxCast data yielded seven modules. Assays and chemicals in the seven modules were distinct. Leave-one-out cross-validation yielded a Q(2) of 0.5416, indicating ToxCast bioactivity data can be predicted by Nebula. Prediction domain analysis showed some types of ToxCast assay data could be more reliably predicted by Nebula than others. Network analysis is a promising approach to understand ToxCast data. Nebula is an effective algorithm for predicting ToxCast bioactivity data, helping fully utilize ToxCast data in the risk assessment of chemicals. Published by Elsevier Ltd.

Structural and compositional analysis of a casting mold sherd from ancient China.

PubMed

Zong, Yunbing; Yao, Shengkun; Lang, Jianfeng; Chen, Xuexiang; Fan, Jiadong; Sun, Zhibin; Duan, Xiulan; Li, Nannan; Fang, Hui; Zhou, Guangzhao; Xiao, Tiqiao; Li, Aiguo; Jiang, Huaidong

2017-01-01

Casting had symbolic significance and was strictly controlled in the Shang dynasty of ancient China. Vessel casting was mainly distributed around the Shang capital, Yin Ruins, which indicates a rigorous centralization of authority. Thus, for a casting mold to be excavated far from the capital region is rare. In addition to some bronze vessel molds excavated at the Buyao Village site, another key discovery of a bronze vessel mold occurred at Daxinzhuang. The Daxinzhuang site was a core area in the east of Shang state and is an important site to study the eastward expansion of the Shang. Here, combining synchrotron X-rays and other physicochemical analysis methods, nondestructive three-dimensional structure imaging and different elemental analyses were conducted on this mold sherd. Through high penetration X-ray tomography, we obtained insights on the internal structure and discovered some pores. We infer that the generation of pores inside the casting mold sherd was used to enhance air permeability during casting. Furthermore, we suppose that the decorative patterns on the surface were carved and not pasted onto it. Considering the previous compositional studies of bronze vessels, the copper and iron elements were analyzed by different methods. Unexpectedly, a larger amount of iron than of copper was detected on the surface. According to the data analysis and archaeological context, the source of iron on the casting mold sherd could be attributed to local soil contamination. A refined compositional analysis confirms that this casting mold was fabricated locally and used for bronze casting.

Processing of IN-718 Lattice Block Castings

NASA Technical Reports Server (NTRS)

Hebsur, Mohan G.

2002-01-01

Recently a low cost casting method known as lattice block casting has been developed by JAM Corporation, Wilmington, Massachusetts for engineering materials such as aluminum and stainless steels that has shown to provide very high stiffness and strength with only a fraction of density of the alloy. NASA Glenn Research Center has initiated research to investigate lattice block castings of high temperature Ni-base superalloys such as the model system Inconel-718 (IN-718) for lightweight nozzle applications. Although difficulties were encountered throughout the manufacturing process , a successful investment casting procedure was eventually developed. Wax formulation and pattern assembly, shell mold processing, and counter gravity casting techniques were developed. Ten IN-718 lattice block castings (each measuring 15-cm wide by 30-cm long by 1.2-cm thick) have been successfully produced by Hitchiner Gas Turbine Division, Milford, New Hampshire, using their patented counter gravity casting techniques. Details of the processing and resulting microstructures are discussed in this paper. Post casting processing and evaluation of system specific mechanical properties of these specimens are in progress.

Multi-modal porous microstructure for high temperature fuel cell application

NASA Astrophysics Data System (ADS)

Wejrzanowski, T.; Haj Ibrahim, S.; Cwieka, K.; Loeffler, M.; Milewski, J.; Zschech, E.; Lee, C.-G.

2018-01-01

In this study, the effect of microstructure of porous nickel electrode on the performance of high temperature fuel cell is investigated and presented based on a molten carbonate fuel cell (MCFC) cathode. The cathode materials are fabricated from slurry consisting of nickel powder and polymeric binder/solvent mixture, using the tape casting method. The final pore structure is shaped through modifying the slurry composition - with or without the addition of porogen(s). The manufactured materials are extensively characterized by various techniques involving: micro-computed tomography (micro-XCT), scanning electron microscopy (SEM), mercury porosimetry, BET and Archimedes method. Tomographic images are also analyzed and quantified to reveal the evolution of pore space due to nickel in situ oxidation to NiO, and infiltration by the electrolyte. Single-cell performance tests are carried out under MCFC operation conditions to estimate the performance of the manufactured materials. It is found that the multi-modal microstructure of MCFC cathode results in a significant enhancement of the power density generated by the reference cell. To give greater insight into the understanding of the effect of microstructure on the properties of the cathode, a model based on 3D tomography image transformation is proposed.

Microorganism Nutrition Processes as a General Route for the Preparation of Bionic Nanocomposites Based on Intractable Polymers.

PubMed

Valentini, L; Bon, S Bittolo; Pugno, N M

2016-08-31

In this paper the fermentation process activated by living microorganisms of the baker's yeast is proposed as a facile assembly method of hybrid nanoparticles at liquid interface. Water dispersion of commercial baker's yeast extract used for bread production, graphene nanoplatelets (GNPs), and carbon nanotubes (CNTs) were added to oil/water interface; when the yeast is activated by adding sugar, the byproduct carbon dioxide bubbles migrate from the water phase to the oil/water interface generating a floating nanostructured film at liquid interface where it is trapped. Starting from this simple method, we propose a general approach for the stabilization of intractable poly(etheretherketone) polymeric particles with GNPs and CNTs at immiscible liquid interface. This process allowed the formation of sintered porous composites with improved mechanical properties. The porous structure of the composites gave rise to a low thermal conductivity making them good candidates for thermal insulating applications. Liquid absorption by these porous composites has been also reported. We believe that this new approach may have applications in the large scale fabrication of nanomaterials and is particularly suited for the preparation of nanocomposites starting from polymers that are intractable by solvent casting.

Quantitative Assessment of Antimicrobial Activity of PLGA Films Loaded with 4-Hexylresorcinol

PubMed Central

Kemme, Michael; Heinzel-Wieland, Regina

2018-01-01

Profound screening and evaluation methods for biocide-releasing polymer films are crucial for predicting applicability and therapeutic outcome of these drug delivery systems. For this purpose, we developed an agar overlay assay embedding biopolymer composite films in a seeded microbial lawn. By combining this approach with model-dependent analysis for agar diffusion, antimicrobial potency of the entrapped drug can be calculated in terms of minimum inhibitory concentrations (MICs). Thus, the topical antiseptic 4-hexylresorcinol (4-HR) was incorporated into poly(lactic-co-glycolic acid) (PLGA) films at different loadings up to 3.7 mg/cm2 surface area through a solvent casting technique. The antimicrobial activity of 4-HR released from these composite films was assessed against a panel of Gram-negative and Gram–positive bacteria, yeasts and filamentous fungi by the proposed assay. All the microbial strains tested were susceptible to PLGA-4-HR films with MIC values down to 0.4% (w/w). The presented approach serves as a reliable method in screening and quantifying the antimicrobial activity of polymer composite films. Moreover, 4-HR-loaded PLGA films are a promising biomaterial that may find future application in the biomedical and packaging sector. PMID:29324696

Influence of reaction time on the structural, optical and electrical performance of copper antimony sulfide nanoparticles using solvothermal method

NASA Astrophysics Data System (ADS)

John, Bincy; Genifer Silvena, G.; Leo Rajesh, A.

2018-05-01

The less toxic and cost effective ternary Cu-Sb-S nanoparticles and thin films were synthesized and deposited using solvothermal and drop casting method. The reactions were carried out at different timings as 12-48 h, in steps of 12 h using ethylene glycol as solvent and polyvinylpyrrolidone (PVP) as surfactant. Systematic analysis revealed that due to the influence of different reaction time, significant and unique changes were occurring on the crystal structure, optical and electrical properties of the material. The synthesized nanopowders and deposited films were characterized by means of X-ray diffraction, Raman analysis, field emission scanning electron microscope with energy dispersive spectrometer, UV-Vis-NIR diffuse reflectance spectroscopy and hall measurement. XRD results showed that as the time increases crystallinity improves and phase transformation from chalcostibite to tetrahedrite occurs. The Optical performance revealed that the bandgap of nanoparticles were in the range of 1.21-1.49 eV. Hall measurements showed that the deposited Cu12Sb4S13 and CuSbS2 films exhibited p-type conductivity with carrier concentration ranging from 1016-1019 cm-3, indicating a promising p-type absorber material for photovoltaic applications.

Beryllium-aluminum alloys for investment castings

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

Nachtrab, W.T.; Levoy, N.

1997-05-01

Beryllium-aluminum alloys containing greater than 60 wt % beryllium are very favorable materials for applications requiring light weight and high stiffness. However, when produced by traditional powder metallurgical methods, these alloys are expensive and have limited applications. To reduce the cost of making beryllium-aluminum components, Nuclear Metals Inc. (NMI) and Lockheed Martin Electronics and Missiles have recently developed a family of patented beryllium-aluminum alloys that can be investment cast. Designated Beralcast, the alloys can achieve substantial weight savings because of their high specific strength and stiffness. In some cases, weight has been reduced by up to 50% over aluminum investmentmore » casting. Beralcast is now being used to make thin wall precision investment castings for several advanced aerospace applications, such as the RAH-66 Comanche helicopter and F-22 jet fighter. This article discusses alloy compositions, properties, casting method, and the effects of cobalt additions on strength.« less

Molecularly imprinted membranes (MIMs) for selective removal of polychlorinated biphenyls (PCBs) in environmental waters: fabrication and characterization.

PubMed

Mkhize, Dennis S; Nyoni, Hlengilizwe; Quinn, Laura P; Mamba, Bhekie B; Msagati, Titus A M

2017-04-01

Molecularly imprinted membranes (MIMs) with selective removal properties for polychlorinated biphenyls (PCBs) were prepared through the phase inversion technique. The MIMs were obtained from casting the viscous solutions of molecularly imprinted polymers (MIPs), polysulfone (PSf), and N-methyl-2-pyrrolidone (NMP) as the casting solvent. Different membranes were prepared at different concentration of MIPs and PSf. The resulting MIMs were characterized by atomic force microscope (AFM), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR). Moreover, the performance of the membranes was evaluated by determining and interpreting the rejection (%), flux (F), permeability coefficient (P), permselectivity factor ( α ' PCB/DDT or anthracene ), and enrichment factors of PCBs, dichlorodiphenyltrichloroethane (p,p'-DDT), and anthracene from model contaminated water using the dead-end filtration cell. Molecularly imprinted membrane prepared with 18 wt% PSf and 20 wt% MIP 4 exhibited a well-defined porous structure, which was accompanied by enhanced PCB enrichment. Furthermore, molecularly imprinted membrane showed good enrichment factors for PCBs even from spiked natural water samples of Hartbeespoort dam.

Porous PVDF/PANI ion-exchange membrane (IEM) modified by polyvinylpyrrolidone (PVP) and lithium chloride in the application of membrane capacitive deionisation (MCDI).

PubMed

Zhang, Yiming; Zhang, Wei; Cházaro-Ruiz, Luis F

2018-05-01

In this work, polyvinylidene fluoride (PVDF)/polyaniline (PANI) heterogeneous anion-exchange membranes filled with pore-forming agents polyvinylpyrrolidone (PVP) and lithium chloride were prepared by the solution-casting technique using the solvent 1-methyl-2-pyrrolidone (NMP) and a two-step phase inversion procedure. Key properties of the as-prepared membranes, such as hydrophilicity, water content, ion exchange capacity, fixed ion concentration, conductivity and transport number were examined and compared between membranes in different conditions. The pore-forming hydrophilic additives PVP and lithium chloride to the casting solution appeared to improve the ion-exchange membranes (IEMs) by increasing the conductivity, transport number and hydrophilicity. The effects of increasing membrane drying time on the porosity of the as-prepared membranes were found to lower membrane porosity by reducing membrane water content. However, pore-forming agents were found to be able to stabilise membrane transport number with different drying times. As-prepared PVDF/PANI anion-exchange membrane with pore-forming agent is demonstrated to be a more efficient candidate for water purification (e.g. desalination) and other industrial applications.

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

DOE PAGES

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph; ...

2018-02-06

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

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

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Incorporating ToxCast and Tox21 Datasets to Rank Biological Activity of Chemicals at Superfund Sites in North Carolina

PubMed Central

Tilley, Sloane K.; Reif, David M.; Fry, Rebecca C.

2017-01-01

Background The Superfund program of the Environmental Protection Agency (EPA) was established in 1980 to address public health concerns posed by toxic substances released into the environment in the United States. Forty-two of the 1328 hazardous waste sites that remain on the Superfund National Priority List are located in the state of North Carolina. Methods We set out to develop a database that contained information on both the prevalence and biological activity of chemicals present at Superfund sites in North Carolina. A chemical characterization tool, the Toxicological Priority Index (ToxPi), was used to rank the biological activity of these chemicals based on their predicted bioavailability, documented associations with biological pathways, and activity in in vitro assays of the ToxCast and Tox21 programs. Results The ten most prevalent chemicals found at North Carolina Superfund sites were chromium, trichloroethene, lead, tetrachloroethene, arsenic, benzene, manganese, 1,2-dichloroethane, nickel, and barium. For all chemicals found at North Carolina Superfund sites, ToxPi analysis was used to rank their biological activity. Through this data integration, residual pesticides and organic solvents were identified to be some of the most highly-ranking predicted bioactive chemicals. This study provides a novel methodology for creating state or regional databases of Superfund sites. Conclusions These data represent a novel integrated profile of the most prevalent chemicals at North Carolina Superfund sites. This information, and the associated methodology, is useful to toxicologists, risk assessors, and the communities living in close proximity to these sites. PMID:28153528

Cast abscess: a case report.

PubMed

Carmichael, Kelly D; Goucher, Nicholas R

2006-01-01

This report describes a case in which a pediatric patient wounded his ankle when he stuck an object inside the cast while trying to scratch himself. The wound became infected and resulted in a limb-threatening abscess. Although most patients treated with casts do not have any significant problems, it is important to emphasize cast care instructions to young patients and their parents. In addition, it may be equally important to advise patients about safe methods to alleviate itching, such as blowing cool air under the cast. In this way, the risk of serious infectious complications can be minimized.

Aminosilicone solvent recovery methods and systems

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

Spiry, Irina Pavlovna; Perry, Robert James; Wood, Benjamin Rue

The present invention is directed to aminosilicone solvent recovery methods and systems. The methods and systems disclosed herein may be used to recover aminosilicone solvent from a carbon dioxide containing vapor stream, for example, a vapor stream that leaves an aminosilicone solvent desorber apparatus. The methods and systems of the invention utilize a first condensation process at a temperature from about 80.degree. C. to about 150.degree. C. and a second condensation process at a temperature from about 5.degree. C. to about 75.degree. C. The first condensation process yields recovered aminosilicone solvent. The second condensation process yields water.

X-Ray Fluorescence Solvent Detection at the Substrate-Adhesive Interface

NASA Technical Reports Server (NTRS)

Wurth, Laura; Evans, Kurt; Weber, Bart; Headrick, Sarah

2005-01-01

With environmental regulations limiting the use of volatile organic compounds, low-vapor pressure solvents have replaced traditional degreasing solvents for bond substrate preparation. When used to clean and prepare porous bond substrates such as phenolic composites, low vapor pressure solvents can penetrate deep into substrate pore networks and remain there for extended periods. Trapped solvents can interact with applied adhesives either prior to or during cure, potentially compromising bond properties. Currently, methods for characterizing solvent time-depth profiles in bond substrates are limited to bulk gravimetric or sectioning techniques. While sectioning techniques such as microtome allow construction of solvent depth profiles, their depth resolution and reliability are limited by substrate type. Sectioning techniques are particularly limited near the adhesive-substrate interface where depth resolution is further limited by adhesive-substrate hardness and, in the case of a partially cured adhesive, mechanical properties differences. Additionally, sectioning techniques cannot provide information about lateral solvent diffusion. Cross-section component mapping is an alternative method for measuring solvent migration in porous substrates that eliminates the issues associated with sectioning techniques. With cross-section mapping, the solvent-wiped substrate is sectioned perpendicular rather than parallel to the wiped surface, and the sectioned surface is analyzed for the solvent or solvent components of interest using a two-dimensional mapping or imaging technique. Solvent mapping can be performed using either direct or indirect methods. With a direct method, one or more solvent components are mapped using red or Raman spectroscopy together with a moveable sample stage and/or focal plane array detector. With an indirect method, an elemental "tag" not present in the substrate is added to the solvent before the substrate is wiped. Following cross sectioning, the tag element can then be mapped by its characteristic x-ray emission using either x-ray fluorescence, or electron-beam energy-and wavelength-dispersive x-ray spectrometry. The direct mapping techniques avoid issues of different diffusion or migration rates of solvents and elemental tags, while the indirect techniques avoid spectral resolution issues in cases where solvents and substrates have adjacent or overlapping peaks. In this study, cross-section component indirect mapping is being evaluated as a method for measuring migration of d-limonene based solvents in glass-cloth phenolic composite (GCP) prior to and during subsequent bonding and epoxy adhesive cure.

Deducing material quality in cast and hot-forged steels by new bending test

NASA Astrophysics Data System (ADS)

Valberg, Henry; Langøy, Morten; Nedreberg, Mette; Helvig, Torgeir

2017-10-01

A special bend test has been developed and applied for the purpose of characterization and comparison of the material ductility in crankpin steel discs manufactured by casting, or casting subsequently followed by hot open-die forging (ODF) or closed-die forging (CDF). The bending test specimen consists of a small rectangular plate of material with a round hole cut out in the middle. The "eye-shape" specimens were cut out from various positions either near to the surface of, or from the interior of the discs. The test method revealed differences in ductility for the investigated materials, and for different depth positions inside the discs. The roughening of the specimen surface on the top-side of the specimen bend also varied dependent on the processing method for the material. Current results show that this test method is useful for evaluation of material quality in differently processed material. Experimental bend test results are presented for differently processed variants of the same material, i.e., crankpin discs either made by solely casting or casting subsequently followed by hot working either by ODF or CDF.

The reliability and validity of measurements of human dental casts made by an intra-oral 3D scanner, with conventional hand-held digital callipers as the comparison measure.

PubMed

Rajshekar, Mithun; Julian, Roberta; Williams, Anne-Marie; Tennant, Marc; Forrest, Alex; Walsh, Laurence J; Wilson, Gary; Blizzard, Leigh

2017-09-01

Intra-oral 3D scanning of dentitions has the potential to provide a fast, accurate and non-invasive method of recording dental information. The aim of this study was to assess the reliability of measurements of human dental casts made using a portable intra-oral 3D scanner appropriate for field use. Two examiners each measured 84 tooth and 26 arch features of 50 sets of upper and lower human dental casts using digital hand-held callipers, and secondly using the measuring tool provided with the Zfx IntraScan intraoral 3D scanner applied to the virtual dental casts. The measurements were repeated at least one week later. Reliability and validity were quantified concurrently by calculation of intra-class correlation coefficients (ICC) and standard errors of measurement (SEM). The measurements of the 110 landmark features of human dental casts made using the intra-oral 3D scanner were virtually indistinguishable from measurements of the same features made using conventional hand-held callipers. The difference of means as a percentage of the average of the measurements by each method ranged between 0.030% and 1.134%. The intermethod SEMs ranged between 0.037% and 0.535%, and the inter-method ICCs ranged between 0.904 and 0.999, for both the upper and the lower arches. The inter-rater SEMs were one-half and the intra-method/rater SEMs were one-third of the inter-method values. This study demonstrates that the Zfx IntraScan intra-oral 3D scanner with its virtual on-screen measuring tool is a reliable and valid method for measuring the key features of dental casts. Copyright © 2017 Elsevier B.V. All rights reserved.

Culture in Psychiatric Epidemiology: Using Ethnography and Multiple Mediator Models to Assess the Relationship of Caste with Depression and Anxiety in Nepal

PubMed Central

Kohrt, Brandon A.; Speckman, Rebecca A.; Kunz, Richard D.; Baldwin, Jennifer L.; Upadhaya, Nawaraj; Acharya, Nanda Raj; Sharma, Vidya Dev; Nepal, Mahendra K.; Worthman, Carol M.

2013-01-01

Background The causes of ethnic and caste-based disparities in mental health are poorly understood. Aim To identify mediators underlying caste-based disparities in mental health in Nepal. Subjects and methods A mixed methods ethnographic and epidemiological study of 307 adults (Dalit/Nepali, n=75; high caste Brahman and Chhetri, n=232) assessed with Nepali versions of Beck Depression (BDI) and Anxiety (BAI) Inventories. Results One third (33.7%) of participants were classified as depressed: Dalit/Nepali 50.0%, high caste 28.4%. One quarter (27.7%) of participants were classified as anxious: Dalit/Nepali 50.7%, high caste 20.3%. Ethnographic research identified four potential mediators: stressful life events, owning few livestock, no household income, and lack of social support. The direct effect of caste was 1.08 (95% CI -1.10—3.27) on depression score and 4.76 (95% CI 2.33—7.19) on anxiety score. All four variables had significant indirect (mediation) effects on anxiety, and all but social support had significant indirect effects on depression. Conclusion Caste-based disparities in mental health in rural Nepal are statistically mediated by poverty, lack of social support, and stressful life events. Interventions should target these areas to alleviate the excess mental health burden born by Dalit/Nepali women and men. PMID:19381985

Competitive allele-specific TaqMan PCR (Cast-PCR) is a sensitive, specific and fast method for BRAF V600 mutation detection in Melanoma patients

PubMed Central

Barbano, Raffaela; Pasculli, Barbara; Coco, Michelina; Fontana, Andrea; Copetti, Massimiliano; Rendina, Michelina; Valori, Vanna Maria; Graziano, Paolo; Maiello, Evaristo; Fazio, Vito Michele; Parrella, Paola

2015-01-01

BRAF codon 600 mutation testing of melanoma patients is mandatory for the choice of the most appropriate therapy in the clinical setting. Competitive allele specific TaqMan PCR (Cast-PCR) technology allows not only the selective amplification of minor alleles, but it also blocks the amplification of non-mutant allele. We genotyped codon 600 of the BRAF gene in 54 patients’ samples by Cast-PCR and bidirectional direct sequence analysis. All the mutations detected by sequencing were also identified by Cast-PCR. In addition, Cast-PCR assay detected four samples carrying mutations and was able to clearly identify two mutations of uncertain interpretation by Sanger sequencing. The limit of detection of Cast-PCR was evaluated by constructing dilution curves of BRAFV600E and BRAFV600K mutated clinical samples mixed with a not-mutated specimens. Both mutations could be detected until a 1:100 mutated/not mutated ratio. Cloning and sequencing of the clones was used to confirm mutations on representative discrepant cases. Cast PCR performances were not affected by intratumour heterogeneity, and less affected by melanin content. Our results indicate that Cast-PCR is a reliable diagnostic tool for the identification of melanoma patients as eligible to be treated with TKIs and might be implemented in the clinical setting as elective screening method. PMID:26690267

Results of clubfoot treatment after manipulation and casting using the Ponseti method: experience in Harare, Zimbabwe.

PubMed

Smythe, Tracey; Chandramohan, Daniel; Bruce, Jane; Kuper, Hannah; Lavy, Christopher; Foster, Allen

2016-10-01

The objective of this study was to evaluate the outcomes of the Ponseti manipulation and casting method for clubfoot in a tertiary hospital in Zimbabwe and explore predictors of these outcomes. A cohort study included children with idiopathic clubfoot managed from 2011 to 2013 at Parirenyatwa Hospital. Demographic data, clinical features and treatment outcomes were extracted from clinic records. The primary outcome measure was the final Pirani score (clubfoot severity measure) after manipulation and casting. Secondary outcomes included change in Pirani score (pre-treatment to end of casting), number of casts for correction, proportion receiving tenotomy and proportion lost to follow up. A total of 218 children (337 feet) were eligible for inclusion. The median age at treatment was 8 months; 173 children (268 feet) completed casting treatment within the study period. The mean length of time for corrective treatment was 10.2 weeks (9.5-10.9 weeks). Of the 45 children who did not complete treatment, 28 were under treatment and 17 were lost to follow up. A Pirani score of 1 or less was achieved in 85% of feet. Mean Pirani score at presentation was 3.80 (SD 1.15) and post-treatment 0.80 (SD 0.56, P-value <0.0001). Severity of deformity and being male were associated with a higher (worse) final Pirani score. Severity and age over two were associated with an increase in the number of casts required to correct deformity. This case series demonstrates that the majority (80%+) of children with clubfoot can achieve a good outcome with the Ponseti manipulation and casting method. © 2016 John Wiley & Sons Ltd.

Blended polymer materials extractable with supercritical carbon dioxide

NASA Astrophysics Data System (ADS)

Cai, Mei

Supercritical carbon dioxide is drawing more and more attention because of its unique solvent properties along with being environmentally friendly. Historically most of the commercial interests of supercritical carbon dioxide extraction are in the food industry, pharmaceutical industry, environmental preservation and polymer processing. Recently attention has shifted from the extraction of relatively simple molecules to more complex systems with a much broader range of physical and chemical transformations. However the available data show that a lot of commercially valuable substances are not soluble in supercritical carbon dioxide due to their polar structures. This fact really limits the application of SCF extraction technology to much broader industrial applications. Therefore, the study of a polymer's solubility in a given supercritical fluid and its thermodynamic behavior becomes one of the most important research topics. The major objective of this dissertation is to develop a convenient and economic way to enhance the polymer's solubility in supercritical carbon dioxide. Further objective is to innovate a new process of making metal casting parts with blended polymer materials developed in this study. The key technique developed in this study to change a polymer's solubility in SCF CO2 is to thermally blend a commercially available and CO2 non-soluble polymer material with a low molecular weight CO2 soluble organic chemical that acts as a co-solute. The mixture yields a plastic material that can be completely solubilized in SCF CO2 over a range of temperatures and pressures. It also exhibits a variety of physical properties (strength, hardness, viscosity, etc.) depending on variations in the mixture ratio. The three organic chemicals investigated as CO2 soluble materials are diphenyl carbonate, naphthalene, and benzophenone. Two commercial polymers, polyethylene glycol and polystyrene, have been investigated as CO2 non-soluble materials. The chemical, physical, thermal, and phase behavior of the blended polymers studied in this dissertation includes solubility in SCF CO2, the melt viscosity, the melting temperature depression, and phase equilibrium under SCF conditions. Several hypotheses are investigated to determine which mechanism plays the major role in the extraction. Finally a novel metal casting process is discussed with the materials developed in this study. This new method utilizes an adhesive or binder film composition for the purpose of building up a casting pattern of resin-bonded aggregate particles. The pattern is then encased in a conventional rigid shell mold that is not susceptible to degradation by SCF CO2. The pattern is then disintegrated within an unaffected mold by exposure to SCF CO 2. This is an efficient and low cost method of making patterns and molds, especially for the casting of a relatively low number of parts such as in prototype evaluations.

Application of the ToxMiner Database: Network Analysis Linking the ToxCast Chemicals to Known Disease-Gene Associations

EPA Science Inventory

The US EPA ToxCast program is using in vitro HTS (High-Throughput Screening) methods to profile and model bioactivity of environmental chemicals. The main goals of the ToxCast program are to generate predictive signatures of toxicity, and ultimately provide rapid and cost-effecti...

Species-specific predictive models of developmental toxicity using the ToxCast chemical library

EPA Science Inventory

EPA’s ToxCastTM project is profiling the in vitro bioactivity of chemicals to generate predictive models that correlate with observed in vivo toxicity. In vitro profiling methods are based on ToxCast data, consisting of over 600 high-throughput screening (HTS) and high-content sc...

The effects of weld-repair and hot isostatic pressing on the fracture properties of Ti-5Al-2.5Sn ELI castings

NASA Technical Reports Server (NTRS)

Misra, M. S.; Lemeshewsky, S.; Bolstad, D.

1982-01-01

The Ti-5Al-2.5Sn extremely low interstitial alloy employed in the large castings which form the critical attachment fittings of the Space Shuttle External Tank was selected because of its high fracture resistance at cryogenic temperatures. Casting was selected over alternative fabrication methods because of its lower cost and adaptability to design changes, although it was found necessary to weld-repair surface and subsurface casting defects in order to reduce the scrap rate and maintain the inherent cost advantage of the castings. Hot Isostatic Pressing was experimentally found to heal the surface and internal defects of the castings, but did not improve tensile or fracture properties and was therefore rejected as a production technique. Production castings are instead weld-repaired, without any mechanical property degradation.

Extracting organic matter on Mars: A comparison of methods involving subcritical water, surfactant solutions and organic solvents

NASA Astrophysics Data System (ADS)

Luong, Duy; Court, Richard W.; Sims, Mark R.; Cullen, David C.; Sephton, Mark A.

2014-09-01

The first step in many life detection protocols on Mars involves attempts to extract or isolate organic matter from its mineral matrix. A number of extraction options are available and include heat and solvent assisted methods. Recent operations on Mars indicate that heating samples can cause the loss or obfuscation of organic signals from target materials, raising the importance of solvent-based systems for future missions. Several solvent types are available (e.g. organic solvents, surfactant based solvents and subcritical water extraction) but a comparison of their efficiencies in Mars relevant materials is missing. We have spiked the well characterised Mars analogue material JSC Mars-1 with a number of representative organic standards. Extraction of the spiked JSC Mars-1 with the three solvent methods provides insights into the relative efficiency of these methods and indicates how they may be used on future Mars missions.

Fabrication of low cost soft tissue prostheses with the desktop 3D printer

NASA Astrophysics Data System (ADS)

He, Yong; Xue, Guang-Huai; Fu, Jian-Zhong

2014-11-01

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.

Fabrication of low cost soft tissue prostheses with the desktop 3D printer

PubMed Central

He, Yong; Xue, Guang-huai; Fu, Jian-zhong

2014-01-01

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods. PMID:25427880

Fabrication of low cost soft tissue prostheses with the desktop 3D printer.

PubMed

He, Yong; Xue, Guang-huai; Fu, Jian-zhong

2014-11-27

Soft tissue prostheses such as artificial ear, eye and nose are widely used in the maxillofacial rehabilitation. In this report we demonstrate how to fabricate soft prostheses mold with a low cost desktop 3D printer. The fabrication method used is referred to as Scanning Printing Polishing Casting (SPPC). Firstly the anatomy is scanned with a 3D scanner, then a tissue casting mold is designed on computer and printed with a desktop 3D printer. Subsequently, a chemical polishing method is used to polish the casting mold by removing the staircase effect and acquiring a smooth surface. Finally, the last step is to cast medical grade silicone into the mold. After the silicone is cured, the fine soft prostheses can be removed from the mold. Utilizing the SPPC method, soft prostheses with smooth surface and complicated structure can be fabricated at a low cost. Accordingly, the total cost of fabricating ear prosthesis is about $30, which is much lower than the current soft prostheses fabrication methods.

Management of Intolerance to Casting the Upper Extremities in Claustrophobic Patients

PubMed Central

Nagura, Issei; Kanatani, Takako; Sumi, Masatoshi; Inui, Atsuyuki; Mifune, Yutaka; Kokubu, Takeshi; Kurosaka, Masahiro

2014-01-01

Introduction. Some patients showed unusual responses to the immobilization without any objective findings with casts in upper extremities. We hypothesized their that intolerance with excessive anxiety to casts is due to claustrophobia triggered by cast immobilization. The aim of this study is to analyze the relevance of cast immobilization to the feeling of claustrophobia and discover how to handle them. Methods. There were nine patients who showed the caustrophobic symptoms with their casts. They were assesed whether they were aware of their claustrophobis themselves. Further we investigated the alternative immobilization to casts. Results. Seven out of nine cases that were aware of their claustrophobic tendencies either were given removable splints initially or had the casts converted to removable splints when they exhibited symptoms. The two patients who were unaware of their latent claustrophobic tendencies were identified when they showed similar claustrophobic symptoms to the previous patients soon after short arm cast application. We replaced the casts with removable splints. This resolved the issue in all cases. Conclusions. We should be aware of the claustrophobia if patients showed unusual responses to the immobilization without any objective findings with casts in upper extremities, where removal splint is practical alternative to cast to continue the treatment successfully. PMID:25379544

AMCC casting development, volume 2

NASA Technical Reports Server (NTRS)

1995-01-01

PCC successfully cast and performed nondestructive testing, FPI and x-ray, on seventeen AMCC castings. Destructive testing, lab analysis and chemical milling, was performed on eleven of the castings and the remaining six castings were shipped to NASA or Aerojet. Two of the six castings shipped, lots 015 and 016, were fully processed per blueprint requirements. PCC has fully developed the gating and processing parameters of this part and feels the part could be implemented into production, after four more castings have been completed to ensure the repeatability of the process. The AMCC casting has been a technically challenging part due to its size, configuration, and alloy type. The height and weight of the wax pattern assembly necessitated the development of a hollow gating system to ensure structural integrity of the shell throughout the investment process. The complexity in the jacket area of the casting required the development of an innovative casting technology that PCC has termed 'TGC' or thermal gradient control. This method of setting up thermal gradients in the casting during solidification represents a significant process improvement for PCC and has been successfully implemented on other programs. The alloy, JBK75, is a relatively new alloy in the investment casting arena and required our engineering staff to learn the gating, processing, and dimensional characteristics of the material.

Partial corrosion casting to assess cochlear vasculature in mouse models of presbycusis and CMV infection.

PubMed

Carraro, Mattia; Park, Albert H; Harrison, Robert V

2016-02-01

Some forms of sensorineural hearing loss involve damage or degenerative changes to the stria vascularis and/or other vascular structures in the cochlea. In animal models, many methods for anatomical assessment of cochlear vasculature exist, each with advantages and limitations. One methodology, corrosion casting, has proved useful in some species, however in the mouse model this technique is difficult to achieve because digestion of non vascular tissue results in collapse of the delicate cast specimen. We have developed a partial corrosion cast method that allows visualization of vasculature along much of the cochlear length but maintains some structural integrity of the specimen. We provide a detailed step-by-step description of this novel technique. We give some illustrative examples of the use of the method in mouse models of presbycusis and cytomegalovirus (CMV) infection. Copyright © 2015 Elsevier B.V. All rights reserved.

Method and apparatus for planar drag strip casting

DOEpatents

Powell, John C.; Campbell, Steven L.

1991-01-01

The present invention is directed to an improved process and apparatus for strip casting. The combination of a planar flow casting nozzle positioned back from the top dead center position with an attached nozzle extension, provides an increased level of casting control and quality. The nozzle extension provides a means of containing the molten pool above the rotating substrate to increase the control of molten metal at the edges of the strip and increase the range of coating thicknesses which may be produced. The level of molten metal in the containment means is regulated to be above the level of melt supplying the casting nozzle which produces a condition of planar drag flow with the casting substrate prior to solidification.

Method and apparatus for planar drag strip casting

DOEpatents

Powell, J.C.; Campbell, S.L.

1991-11-12

The present invention is directed to an improved process and apparatus for strip casting. The combination of a planar flow casting nozzle positioned back from the top dead center position with an attached nozzle extension, provides an increased level of casting control and quality. The nozzle extension provides a means of containing the molten pool above the rotating substrate to increase the control of molten metal at the edges of the strip and increase the range of coating thicknesses which may be produced. The level of molten metal in the containment means is regulated to be above the level of melt supplying the casting nozzle which produces a condition of planar drag flow with the casting substrate prior to solidification. 5 figures.

Method and apparatus for casting conductive and semi-conductive materials

DOEpatents

Ciszek, T.F.

1984-08-13

A method and apparatus is disclosed for casting conductive and semi-conductive materials. The apparatus includes a plurality of conductive members arranged to define a container-like area having a desired cross-sectional shape. A portion or all of the conductive or semi-conductive material which is to be cast is introduced into the container-like area. A means is provided for inducing the flow of an electrical current in each of the conductive members, which currents act collectively to induce a current flow in the material. The induced current flow through the conductive members is in a direction substantially opposite to the induced current flow in the material so that the material is repelled from the conductive members during the casting process.

Method and apparatus for casting conductive and semiconductive materials

DOEpatents

Ciszek, Theodore F.

1986-01-01

A method and apparatus is disclosed for casting conductive and semiconduce materials. The apparatus includes a plurality of conductive members arranged to define a container-like area having a desired cross-sectional shape. A portion or all of the conductive or semiconductive material which is to be cast is introduced into the container-like area. A means is provided for inducing the flow of an electrical current in each of the conductive members, which currents act collectively to induce a current flow in the material. The induced current flow through the conductive members is in a direction substantially opposite to the induced current flow in the material so that the material is repelled from the conductive members during the casting process.

Cast B2-phase iron-aluminum alloys with improved fluidity

DOEpatents

Maziasz, Philip J.; Paris, Alan M.; Vought, Joseph D.

2002-01-01

Systems and methods are described for iron aluminum alloys. A composition includes iron, aluminum and manganese. A method includes providing an alloy including iron, aluminum and manganese; and processing the alloy. The systems and methods provide advantages because additions of manganese to iron aluminum alloys dramatically increase the fluidity of the alloys prior to solidification during casting.

One-pot preparation of unsaturated polyester nanocomposites containing functionalized graphene sheets via a novel solvent-exchange method

USDA-ARS?s Scientific Manuscript database

This paper reports a convenient one-pot method integrating a novel solvent-exchange method into in situ melt polycondensation to fabricate unsaturated polyester nanocomposites containing functionalized graphene sheets (FGS). A novel solvent-exchange method was first developed to prepare graphene oxi...

Non-rigid Reconstruction of Casting Process with Temperature Feature

NASA Astrophysics Data System (ADS)

Lin, Jinhua; Wang, Yanjie; Li, Xin; Wang, Ying; Wang, Lu

2017-09-01

Off-line reconstruction of rigid scene has made a great progress in the past decade. However, the on-line reconstruction of non-rigid scene is still a very challenging task. The casting process is a non-rigid reconstruction problem, it is a high-dynamic molding process lacking of geometric features. In order to reconstruct the casting process robustly, an on-line fusion strategy is proposed for dynamic reconstruction of casting process. Firstly, the geometric and flowing feature of casting are parameterized in manner of TSDF (truncated signed distance field) which is a volumetric block, parameterized casting guarantees real-time tracking and optimal deformation of casting process. Secondly, data structure of the volume grid is extended to have temperature value, the temperature interpolation function is build to generate the temperature of each voxel. This data structure allows for dynamic tracking of temperature of casting during deformation stages. Then, the sparse RGB features is extracted from casting scene to search correspondence between geometric representation and depth constraint. The extracted color data guarantees robust tracking of flowing motion of casting. Finally, the optimal deformation of the target space is transformed into a nonlinear regular variational optimization problem. This optimization step achieves smooth and optimal deformation of casting process. The experimental results show that the proposed method can reconstruct the casting process robustly and reduce drift in the process of non-rigid reconstruction of casting.

Search for promising compositions for developing new multiphase casting alloys based on Al-Cu-Mg matrix using thermodynamic calculations and mathematic simulation

NASA Astrophysics Data System (ADS)

Zolotorevskii, V. S.; Pozdnyakov, A. V.; Churyumov, A. Yu.

2012-11-01

A calculation-experimental study is carried out to improve the concept of searching for new alloying systems in order to develop new casting alloys using mathematical simulation methods in combination with thermodynamic calculations. The results show the high effectiveness of the applied methods. The real possibility of selecting the promising compositions with the required set of casting and mechanical properties is exemplified by alloys with thermally hardened Al-Cu and Al-Cu-Mg matrices, as well as poorly soluble additives that form eutectic components using mainly the calculation study methods and the minimum number of experiments.

Method to prevent/mitigate steam explosions in casting pits

DOEpatents

Taleyarkhan, Rusi P.

1996-01-01

Steam explosions can be prevented or mitigated during a metal casting process by the placement of a perforated flooring system in the casting pit. An upward flow of compressed gas through this perforated flooring system is introduced during the casting process to produce a buffer layer between any spilled molten metal and the cooling water in the reservoir. This buffer layer provides a hydrodynamic layer which acts to prevent or mitigate steam explosions resulting from hot, molten metal being spilled into or onto the cooling water.

The extraction of essential oil from patchouli leaves (Pogostemon cablin Benth) using microwave hydrodistillation and solvent-free microwave extraction methods

NASA Astrophysics Data System (ADS)

Putri, D. K. Y.; Kusuma, H. S.; Syahputra, M. E.; Parasandi, D.; Mahfud, M.

2017-12-01

Patchouli plant (Pogostemon cablin Benth) is one of the important essential oil-producing plant, contributes more than 50% of total exports of Indonesia’s essential oil. However, the extraction of patchouli oil that has been done in Indonesia is generally still used conventional methods that require enormous amount of energy, high solvent usage, and long time of extraction. Therefore, in this study, patchouli oil extraction was carried out by using microwave hydrodistillation and solvent-free microwave extraction methods. Based on this research, it is known that the extraction of patchouli oil using microwave hydrodistillation method with longer extraction time (240 min) only produced patchouli oil’s yield 1.2 times greater than solvent-free microwave extraction method which require faster extraction time (120 min). Otherwise the analysis of electric consumption and the environmental impact, the solvent-free microwave extraction method showed a smaller amount when compared with microwave hydrodistillation method. It is conclude that the use of solvent-free microwave extraction method for patchouli oil extraction is suitably method as a new green technique.

Cure shrinkage in casting resins

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

Spencer, J. Brock

2015-02-01

A method is described whereby the shrinkage of a casting resin can be determined. Values for the shrinkage of several resin systems in frequent use by Sandia have been measured. A discussion of possible methods for determining the stresses generated by cure shrinkage and thermal contraction is also included.

Laser Microperforated Biodegradable Microbial Polyhydroxyalkanoate Substrates for Tissue Repair Strategies: An Infrared Microspectroscopy Studey

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

G Ellis; P Cano; M Jadraque

Flexible and biodegradable film substrates prepared by solvent casting from poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBHV) solutions in chloroform were microperforated by ultraviolet laser ablation and subsequently characterized using infrared (IR) microspectroscopy and imaging techniques and scanning electron microscopy (SEM). Both transmission synchrotron IR microspectroscopy and attenuated total reflectance microspectroscopy measurements demonstrate variations in the polymer at the ablated pore rims, including evidence for changes in chemical structure and crystallinity. SEM results on microperforated PHBHV substrates after cell culture demonstrated that the physical and chemical changes observed in the biomaterial did not hinder cell migration through the pores.

Materials Chemistry and Performance of Silicone-Based Replicating Compounds.

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

Brumbach, Michael T.; Mirabal, Alex James; Kalan, Michael

Replicating compounds are used to cast reproductions of surface features on a variety of materials. Replicas allow for quantitative measurements and recordkeeping on parts that may otherwise be difficult to measure or maintain. In this study, the chemistry and replicating capability of several replicating compounds was investigated. Additionally, the residue remaining on material surfaces upon removal of replicas was quantified. Cleaning practices were tested for several different replicating compounds. For all replicating compounds investigated, a thin silicone residue was left by the replica. For some compounds, additional inorganic species could be identified in the residue. Simple solvent cleaning could removemore » some residue.« less

Molten salt-supported polycondensation of optically active diacid monomers with an aromatic thiazole-bearing diamine using microwave irradiation.

PubMed

Mallakpour, Shadpour; Zadehnazari, Amin

2014-05-01

Microwave heating was used to prepare optically active thiazole-bearing poly(amide-imide)s. Polymerization reactions were carried out in the molten tetrabutylammonium bromide as a green molten salt medium and triphenyl phosphite as the homogenizer. Structural elucidation of the compounds was performed by Fourier transform infrared and NMR spectroscopic data and elemental analysis results. The polymeric samples were readily soluble in various organic solvents, forming low-colored and flexible thin films via solution casting. They showed high thermal stability with decomposition temperature being above 360 °C. They were assembled randomly in a nanoscale size.

Molten salt-supported polycondensation of optically active diacid monomers with an aromatic thiazole-bearing diamine using microwave irradiation

PubMed Central

Mallakpour, Shadpour; Zadehnazari, Amin

2013-01-01

Microwave heating was used to prepare optically active thiazole-bearing poly(amide-imide)s. Polymerization reactions were carried out in the molten tetrabutylammonium bromide as a green molten salt medium and triphenyl phosphite as the homogenizer. Structural elucidation of the compounds was performed by Fourier transform infrared and NMR spectroscopic data and elemental analysis results. The polymeric samples were readily soluble in various organic solvents, forming low-colored and flexible thin films via solution casting. They showed high thermal stability with decomposition temperature being above 360 °C. They were assembled randomly in a nanoscale size. PMID:25685498

Development of an expert system for the simulation model for casting metal substructure of a metal-ceramic crown design.

PubMed

Matin, Ivan; Hadzistevic, Miodrag; Vukelic, Djordje; Potran, Michal; Brajlih, Tomaz

2017-07-01

Nowadays, the integrated CAD/CAE systems are favored solutions for the design of simulation models for casting metal substructures of metal-ceramic crowns. The worldwide authors have used different approaches to solve the problems using an expert system. Despite substantial research progress in the design of experts systems for the simulation model design and manufacturing have insufficiently considered the specifics of casting in dentistry, especially the need for further CAD, RE, CAE for the estimation of casting parameters and the control of the casting machine. The novel expert system performs the following: CAD modeling of the simulation model for casting, fast modeling of gate design, CAD eligibility and cast ability check of the model, estimation and running of the program code for the casting machine, as well as manufacturing time reduction of the metal substructure. The authors propose an integration method using common data model approach, blackboard architecture, rule-based reasoning and iterative redesign method. Arithmetic mean roughness values was determinated with constant Gauss low-pass filter (cut-off length of 2.5mm) according to ISO 4287 using Mahr MARSURF PS1. Dimensional deviation between the designed model and manufactured cast was determined using the coordinate measuring machine Zeiss Contura G2 and GOM Inspect software. The ES allows for obtaining the castings derived roughness grade number N7. The dimensional deviation between the simulation model of the metal substructure and the manufactured cast is 0.018mm. The arithmetic mean roughness values measured on the casting substructure are from 1.935µm to 2.778µm. The realized developed expert system with the integrated database is fully applicable for the observed hardware and software. Values of the arithmetic mean roughness and dimensional deviation indicate that casting substructures are surface quality, which is more than enough and useful for direct porcelain veneering. The manufacture of the substructure shows that the proposed ES allows the improvement of the design process while reducing the manufacturing time. Copyright © 2017 Elsevier B.V. All rights reserved.

Structural and compositional analysis of a casting mold sherd from ancient China

PubMed Central

Zong, Yunbing; Yao, Shengkun; Lang, Jianfeng; Chen, Xuexiang; Fan, Jiadong; Sun, Zhibin; Duan, Xiulan; Li, Nannan; Fang, Hui; Zhou, Guangzhao; Xiao, Tiqiao; Li, Aiguo; Jiang, Huaidong

2017-01-01

Casting had symbolic significance and was strictly controlled in the Shang dynasty of ancient China. Vessel casting was mainly distributed around the Shang capital, Yin Ruins, which indicates a rigorous centralization of authority. Thus, for a casting mold to be excavated far from the capital region is rare. In addition to some bronze vessel molds excavated at the Buyao Village site, another key discovery of a bronze vessel mold occurred at Daxinzhuang. The Daxinzhuang site was a core area in the east of Shang state and is an important site to study the eastward expansion of the Shang. Here, combining synchrotron X-rays and other physicochemical analysis methods, nondestructive three-dimensional structure imaging and different elemental analyses were conducted on this mold sherd. Through high penetration X-ray tomography, we obtained insights on the internal structure and discovered some pores. We infer that the generation of pores inside the casting mold sherd was used to enhance air permeability during casting. Furthermore, we suppose that the decorative patterns on the surface were carved and not pasted onto it. Considering the previous compositional studies of bronze vessels, the copper and iron elements were analyzed by different methods. Unexpectedly, a larger amount of iron than of copper was detected on the surface. According to the data analysis and archaeological context, the source of iron on the casting mold sherd could be attributed to local soil contamination. A refined compositional analysis confirms that this casting mold was fabricated locally and used for bronze casting. PMID:28296963

Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis.

PubMed

Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel

2017-10-20

The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m 3 ) and benzene (1.7±0.5μg/m 3 ) is lower when using TGDE compared to methanol, which was previously used (385μg/m 3 for TCE and 130μg/m 3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ 13 C analysis. Due to a different analytical procedure, the method detection limit associated with δ 37 Cl analysis was found to be 156±6μg/m 3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling method without the need to determine the initial gas phase TCE concentration. The simplified field deployment approach of the solvent-based dissolution method combined with the conventional analytical procedure used for groundwater samples substantially facilitates the application of CSIA to gas phase studies. Copyright © 2017 Elsevier B.V. All rights reserved.

Electroslag Treatment of Liquid Cast Iron

NASA Astrophysics Data System (ADS)

Grachev, V. A.

2018-01-01

The processes that occur in the liquid metal-slag system during electroslag treatment of cast iron are studied from an electrochemical standpoint. The role of electrolysis in the electroslag process is shown, and a method for producing high-strength cast iron with globular graphite using electrolysis of a slag containing magnesium oxides and fluorides is proposed and tested.

The CAST Initiative in Guam: A Model of Effective Teachers Teaching Teachers

ERIC Educational Resources Information Center

Zuercher, Deborah K.; Kessler, Cristy; Yoshioka, Jon

2011-01-01

The CAST (content area specialized training) model of professional development enables sustainable teacher leadership and is responsive to the need for culturally relevant educational practices. The purpose of this paper is to share the background, methods, findings and recommendations of a case study on the CAST initiative in Guam. The case study…

Application of the ToxMiner Database: Network Analysis of Linkage between ToxCast Phase I Chemicals and Thyroid Related Disease Outcomes

EPA Science Inventory

The US EPA ToxCast program is using in vitro HTS (High-Throughput Screening) methods to profile and model bioactivity of environmental chemicals. The main goals of the ToxCast program are to generate predictive signatures of toxicity, and ultimately provide rapid and cost-effecti...

Fluxing agent for metal cast joining

DOEpatents

Gunkel, Ronald W.; Podey, Larry L.; Meyer, Thomas N.

2002-11-05

A method of joining an aluminum cast member to an aluminum component. The method includes the steps of coating a surface of an aluminum component with flux comprising cesium fluoride, placing the flux coated component in a mold, filling the mold with molten aluminum alloy, and allowing the molten aluminum alloy to solidify thereby joining a cast member to the aluminum component. The flux preferably includes aluminum fluoride and alumina. A particularly preferred flux includes about 60 wt. % CsF, about 30 wt. % AlF.sub.3, and about 10 wt. % Al.sub.2 O.sub.3.

Conventionally cast and forged copper alloy for high-heat-flux thrust chambers

NASA Technical Reports Server (NTRS)

Kazaroff, John M.; Repas, George A.

1987-01-01

The combustion chamber liner of the space shuttle main engine is made of NARloy-Z, a copper-silver-zirconium alloy. This alloy was produced by vacuum melting and vacuum centrifugal casting; a production method that is currently now available. Using conventional melting, casting, and forging methods, NASA has produced an alloy of the same composition called NASA-Z. This report compares the composition, microstructure, tensile properties, low-cycle fatigue life, and hot-firing life of these two materials. The results show that the materials have similar characteristics.

3D printing in X-ray and Gamma-Ray Imaging: A novel method for fabricating high-density imaging apertures☆

PubMed Central

Miller, Brian W.; Moore, Jared W.; Barrett, Harrison H.; Fryé, Teresa; Adler, Steven; Sery, Joe; Furenlid, Lars R.

2011-01-01

Advances in 3D rapid-prototyping printers, 3D modeling software, and casting techniques allow for cost-effective fabrication of custom components in gamma-ray and X-ray imaging systems. Applications extend to new fabrication methods for custom collimators, pinholes, calibration and resolution phantoms, mounting and shielding components, and imaging apertures. Details of the fabrication process for these components, specifically the 3D printing process, cold casting with a tungsten epoxy, and lost-wax casting in platinum are presented. PMID:22199414

Metal casts showing the three-dimensional structure of the human inner ear were converted into jewelry.

PubMed

Heywood, Peter

2015-06-01

This article describes a straightforward method for making metal casts of the human inner ear developed in 1937 by M. Wharton Young of Howard University College of Medicine. These casts were used to study anatomy, but there do not appear to be any published photographs of the casts. Inner ear casts converted into jewelry provide the only known images of this work. Later, Young studied the inner ear in living rhesus monkeys by injecting mercury into their membranous labyrinths. Young's investigations indicated a blind-ending perilymphatic sac that was not in continuity with the subarachnoid space.

METHOD FOR SOLVENT-ISOSTATIC PRESSING

DOEpatents

Archibald, P.B.

1962-09-18

This invention provides a method for producing densely compacted bodies having relatively large dimensions. The method comprises the addition of a small quantity of a suitable solvent to a powder which is to be compacted. The solvent- moistened powder is placed inside a flexible bag, and the bag is suspended in an isostatic press. The solvent is squeezed out of the powder by the isostatic pressure, and the resulting compacted body is recovered. The presence of the solvent markedly decreases the proportion of void space in the powder, thereby resulting in a denser, more homogeneous compact. Another effect of the solvent is that it allows the isostatic pressing operation to be conducted at substantially lower pressures than are conventionally employed. (AEC)

Comparison of molecular orientation and phase transition behaviors in the two kinds of ordered ultrathin films of reversed duckweed polymer ES-3 studied by infrared grazing reflection-absorption spectroscopy

NASA Astrophysics Data System (ADS)

Wang, Qiang; Xu, Weiqing; Zhao, Bing

2003-03-01

A multilayer LB film and a casting film of reversed duckweed polymer ES-3 on Au-evaporated glass slides were investigated by Fourier Transform infrared grazing reflection-absorption spectroscopy. It is found that the two kinds of ordered ultrathin films have different orientation of alkyl chains, nearly perpendicular to the substrate surface for the LB film while rather tilted for the casting film. The studies on their thermal transition behaviors indicate that both of the films have three phase transition processes, respectively, occurring near 65, 105 and 140 °C for the former while near 80, 105 and 140 °C for the latter, but show different transition behavior in the each corresponding transition process. It is referred that at room temperature there are island-like domain structures formed in the LB film, but no ones in the casting film; however, the latter can form the domain structures between the first two transition points due to the desorption of solvents. The formation of domain structure seems to play two important roles, one of which is to make alkyl chains more perpendicular to the substrate surface, and the other to make alkyl chains more packed closely. Thermal cyclic experiments reveal that neither of the films could return to its original state after thermal cyclic treatment up to the temperature, which is above the third transition point, although its alkyl chain becomes highly ordered again.

Photoactive chitosan switching on bone-like apatite deposition.

PubMed

Chiono, Valeria; Gentile, Piergiorgio; Boccafoschi, Francesca; Carmagnola, Irene; Ninov, Momchil; Georgieva, Ventsislava; Georgiev, George; Ciardelli, Gianluca

2010-02-08

The work was focused on the synthesis and characterization of the chitosan-g-fluorescein (CHFL) conjugate polymer as a biocompatible amphiphilic water-soluble photosensitizer, able to stimulate hydroxyapatite deposition upon visible light irradiation. Fluorescein (FL) grafting to chitosan (CH) chains was confirmed by UV-vis analysis of water solutions of FL and CHFL and by Fourier transform infrared spectroscopy (FTIR-ATR) analysis of CHFL and CH. Smooth CHFL cast films with 4 microm thickness were obtained by solvent casting. Continuous exposure to visible light for 7 days was found to activate the deposition of calcium phosphate crystals from a conventional simulated body fluid (SBF 1.0x) on the surface of CHFL cast films. EDX and FTIR-ATR analyses confirmed the apatite nature of the deposited calcium phosphate crystals. CHFL films preincubated in SBF (1.0x) solution under visible light irradiation and in the dark for 7 days were found to support the in vitro adhesion and proliferation of MG63 osteoblast-like cells (MTT viability test; 1-3 days culture time). On the other hand, the mineralization ability of MG63 osteoblast-like cells was significantly improved on CHFL films preincubated under visible light exposure (alkaline phosphatase activity (ALP) test for 1, 3, 7, and 14 days). The use of photoactive biocompatible conjugate polymer, such as CHFL, may lead to new therapeutic options in the field of bone/dental repair, exploiting the photoexcitation mechanism as a tool for biomineralization.

[Study on the effect of different impression methods on the marginal fit of all-ceramic crowns].

PubMed

Zhan, Lilin; Zeng, Liwei; Chen, Ping; Liao, Lan; Li, Shiyue; Liu, Renying

2015-08-01

To investigate the effect of three different impression methods on the marginal fit of all-ceramic crowns. The three methods include scanning silicone rubber impression, cast models, and direct optical impression. The polymethyl methacrylate (PMMA) material of a mandibular first molar in standard model was prepared with 16 models duplicated. The all-ceramic crowns were prepared using three different impression methods. Accurate impressions were made using silicone rubber, and the cast models were obtained. The PMMA models, silicone rubber impressions, and cast models were scanned, and digital models of three groups were obtained to produce 48 zirconia all-ceramic crowns with computer aided design/computer aided manufacture. The marginal fit of these groups was measured by silicone rubber gap impression. Statistical analysis was performed with SPSS 17.0 software. The marginal fit of direct optical impression groups, silicone rubber impression groups, cast model groups was (69.18±9.47), (81.04±10.88), (84.42±9.96) µm. A significant difference was observed in the marginal fit of the direct optical impression groups and the other groups (P<0.05). No statistically significant difference was observed in the marginal fit of the silicone rubber impression groups and the cast model groups (P>0.05). All marginal measurement sites are clinically acceptable by the three different impression scanning methods. The silicone rubber impression scanning method can be used for all-ceramic restorations.

A Winning Cast

NASA Technical Reports Server (NTRS)

2001-01-01

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.

Prediction of Phase Behavior of Spray-Dried Amorphous Solid Dispersions: Assessment of Thermodynamic Models, Standard Screening Methods and a Novel Atomization Screening Device with Regard to Prediction Accuracy

PubMed Central

Chavez, Pierre-François; Meeus, Joke; Robin, Florent; Schubert, Martin Alexander; Somville, Pascal

2018-01-01

The evaluation of drug–polymer miscibility in the early phase of drug development is essential to ensure successful amorphous solid dispersion (ASD) manufacturing. This work investigates the comparison of thermodynamic models, conventional experimental screening methods (solvent casting, quench cooling), and a novel atomization screening device based on their ability to predict drug–polymer miscibility, solid state properties (Tg value and width), and adequate polymer selection during the development of spray-dried amorphous solid dispersions (SDASDs). Binary ASDs of four drugs and seven polymers were produced at 20:80, 40:60, 60:40, and 80:20 (w/w). Samples were systematically analyzed using modulated differential scanning calorimetry (mDSC) and X-ray powder diffraction (XRPD). Principal component analysis (PCA) was used to qualitatively assess the predictability of screening methods with regards to SDASD development. Poor correlation was found between theoretical models and experimentally-obtained results. Additionally, the limited ability of usual screening methods to predict the miscibility of SDASDs did not guarantee the appropriate selection of lead excipient for the manufacturing of robust SDASDs. Contrary to standard approaches, our novel screening device allowed the selection of optimal polymer and drug loading and established insight into the final properties and performance of SDASDs at an early stage, therefore enabling the optimization of the scaled-up late-stage development. PMID:29518936

Synthesis of PDLLA/PLLA-bentonite nanocomposite through sonication

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

Sitompul, Johnner, E-mail: sitompul@che.itb.ac.id; Setyawan, Daru, E-mail: daru.setyawan@gmail.com; Kim, Daniel Young Joon, E-mail: daniel.kim12321@gmail.com

2016-04-19

This paper concerns the synthesis of poly(D,L-lactic acid)/poly(L-lactic acid) bentonite nanocomposites. Poly (D,L-lactic acid) (PDLLA) was synthesized using lactic acid through the ZnO-catalyzed direct polycondensation method at vacuum pressure and poly(L-lactic acid) (PLLA) was synthesized with L-lactide by ring-opening polymerization method. The PDLLA/PLLA-bentonite nanocomposite films were synthesized using the solvent casting method. The nanoclay, bentonite, was prepared using the solution-intercalation method by dissolving the nanoparticles into chloroform before sonication. In this study, PDLLA/PLLA-bentonite nanocomposite films were produced using variable amounts of nanoclay and sonication times during the mixing of PDLLA/PLLA and bentonite. The properties of the PDLLA/PLLA nanocomposites were thenmore » characterized using the X-ray Diffraction (XRD), Universal Testing Machine (UTM), Water Vapor Permeability (WVP) tests, and the enzymatic biodegradability test. The XRD test was used to measure the intercalation of nanoclay layers in the PDLLA/PLLA matrix and the PDLLA/PLLA-bentonite intercalated nanocomposite films. It was found through these various tests that adding bentonite to the PDLLA/PLLA increases tensile strength to 56.76 MP. Furthermore, the biodegradability increases as well as the barrier properties of the polymers The different sonication time used during the mixing of the polymer solution with bentonite also affected the properties of the PDLLA/PLLA-bentonite nanocomposite films.« less

Preparation and characterization of bio-nanocomposite films of agar and silver nanoparticles: laser ablation method.

PubMed

Rhim, Jong-Whan; Wang, Long-Feng; Lee, Yonghoon; Hong, Seok-In

2014-03-15

Silver nanoparticles (AgNPs) were prepared by a laser ablation method and composite films with the AgNPs and agar were prepared by solvent casting method. UV-vis absorbance test and transmission electron microscopy (TEM) analysis results revealed that non-agglomerated spherical AgNPs were formed by the laser ablation method. The surface color of the resulting agar/AgNPs films exhibited the characteristic plasmonic effect of the AgNPs with the maximum absorption peaks of 400-407 nm. X-ray diffraction (XRD) test results also exhibited characteristic AgNPs crystals with diffraction peaks observed at 2θ values of 38.39°, 44.49°, and 64.45°, which were corresponding to (111), (200), and (220) crystallographic planes of face-centered cubic (fcc) silver crystals, respectively. Thermogravimetric analysis (TGA) results showed that thermal stability of the agar/AgNPs composite films was increased by the inclusion of metallic silver. Water vapor barrier properties and surface hydrophobicity of the agar/AgNPs films increased slightly with the increase in AgNPs content but they were not statistically significant (p>0.05), while mechanical strength and stiffness of the composite films decreased slightly (p<0.05). The agar/AgNPs films exhibited distinctive antimicrobial activity against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli O157:H7) bacterial pathogens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Casting Control of Floating-films into Ribbon-shape Structure by modified Dynamic FTM

NASA Astrophysics Data System (ADS)

Tripathi, A.; Pandey, M.; Nagamatsu, S.; Pandey, S. S.; Hayase, S.; Takashima, W.

2017-11-01

We have developed a new method to obtain Ribbon-shaped floating films via dynamic casting of floating-film and transfer method (dynamic-FTM). Dynamic-FTM is a unique method to prepare oriented thin-film of conjugated polymers (CPs) which is quick and easy. This method has several advantages as compared to the other conventional casting procedure to prepare oriented CP films. In the conventional dynamic FTM appearance of large scale circular orientation poses difficulty not only for practical applications but also hinders the detailed analysis of the orientation mechanism. In this present work, pros and cons of this newly proposed ribbon-shaped floating-film have been discussed in detail from those of the conventional floating-film prepared by dynamic-FTM.

Stress ratio effects in fatigue of lost foam cast aluminum alloy 356

NASA Astrophysics Data System (ADS)

Palmer, David E.

Lost foam casting is a highly versatile metalcasting process that offers significant benefits in terms of design flexibility, energy consumption, and environmental impact. In the present work, the fatigue behavior of lost foam cast aluminum alloy 356, in conditions T6 and T7, was investigated, under both zero and non-zero mean stress conditions, with either as-cast or machined surface finish. Scanning electron microscopy was used to identify and measure the defect from which fatigue fracture initiated. Based on the results, the applicability of nine different fatigue mean stress equations was compared. The widely-used Goodman equation was found to be highly non-conservative, while the Stulen, Topper-Sandor, and Walker equations performed reasonably well. Each of these three equations includes a material-dependent term for stress ratio sensitivity. The stress ratio sensitivity was found to be affected by heat treatment, with the T6 condition having greater sensitivity than the T7 condition. The surface condition (as-cast vs. machined) did not significantly affect the stress ratio sensitivity. The fatigue life of as-cast specimens was found to be approximately 60--70% lower than that of machined specimens at the same equivalent stress. This reduction could not be attributed to pore size alone, and is suspected to be due to the greater concentration of pyrolysis products at the as-cast surface. Directions for future work, including improved testing methods and some possible methods of improving the properties of lost foam castings, are discussed.

Novel technologies for the lost foam casting process

NASA Astrophysics Data System (ADS)

Jiang, Wenming; Fan, Zitian

2018-03-01

Lost foam casting (LFC) is a green precision casting process categorized as a near net forming technology. Yet, despite its popularity, it still suffers from some technological problems, such as poor filling ability of the castings, coarse and non-dense microstructure, low mechanical properties for the Al and Mg LFC processes, and defective carburization for the low carbon steel LFC process. These drawbacks restrict the development and widespread application of the LFC process. To solve these problems, the present study developed several novel LFC technologies, namely, LFC technologies under vacuum and low pressure, vibration solidification, and pressure solidification conditions; expendable shell casting technology; and preparation technology of bimetallic castings based on the LFC process. The results showed that the LFC under vacuum and low pressure evidently improved the filling ability and solved the oxidization problem of the alloys, which is suitable for producing complex and thinwall castings. The vibration and pressure solidifications increased the compactness of the castings and refined the microstructure, significantly improving the mechanical properties of the castings. The expendable shell casting technology could solve the pore, carburization, and inclusion defects of the traditional LFC method, obtaining castings with acceptable surface quality. Moreover, the Al/Mg and Al/Al bimetallic castings with acceptable metallurgical bonding were successfully fabricated using the LFC process. These proposed novel LFC technologies can solve the current technological issues and promote the technological progress of the LFC process.

Rapid Prototyping Technology for Manufacturing GTE Turbine Blades

NASA Astrophysics Data System (ADS)

Balyakin, A. V.; Dobryshkina, E. M.; Vdovin, R. A.; Alekseev, V. P.

2018-03-01

The conventional approach to manufacturing turbine blades by investment casting is expensive and time-consuming, as it takes a lot of time to make geometrically precise and complex wax patterns. Turbine blade manufacturing in pilot production can be sped up by accelerating the casting process while keeping the geometric precision of the final product. This paper compares the rapid prototyping method (casting the wax pattern composition into elastic silicone molds) to the conventional technology. Analysis of the size precision of blade casts shows that silicon-mold casting features sufficient geometric precision. Thus, this method for making wax patterns can be a cost-efficient solution for small-batch or pilot production of turbine blades for gas-turbine units (GTU) and gas-turbine engines (GTE). The paper demonstrates how additive technology and thermographic analysis can speed up the cooling of wax patterns in silicone molds. This is possible at an optimal temperature and solidification time, which make the process more cost-efficient while keeping the geometric quality of the final product.

Homogenizing Advanced Alloys: Thermodynamic and Kinetic Simulations Followed by Experimental Results

NASA Astrophysics Data System (ADS)

Jablonski, Paul D.; Hawk, Jeffrey A.

2017-01-01

Segregation of solute elements occurs in nearly all metal alloys during solidification. The resultant elemental partitioning can severely degrade as-cast material properties and lead to difficulties during post-processing (e.g., hot shorts and incipient melting). Many cast articles are subjected to a homogenization heat treatment in order to minimize segregation and improve their performance. Traditionally, homogenization heat treatments are based upon past practice or time-consuming trial and error experiments. Through the use of thermodynamic and kinetic modeling software, NETL has designed a systematic method to optimize homogenization heat treatments. Use of the method allows engineers and researchers to homogenize casting chemistries to levels appropriate for a given application. The method also allows for the adjustment of heat treatment schedules to fit limitations on in-house equipment (capability, reliability, etc.) while maintaining clear numeric targets for segregation reduction. In this approach, the Scheil module within Thermo-Calc is used to predict the as-cast segregation present within an alloy, and then diffusion controlled transformations is used to model homogenization kinetics as a function of time and temperature. Examples of computationally designed heat treatments and verification of their effects on segregation and properties of real castings are presented.

Microstructure characterization and corrosion resistance properties of Pb-Sb alloys for lead acid battery spine produced by different casting methods.

PubMed

Seikh, Asiful H; Sherif, El-Sayed M; Khan Mohammed, Sohail M A; Baig, Muneer; Alam, Mohammad Asif; Alharthi, Nabeel

2018-01-01

The aim of this study is to find out the microstructure, hardness, and corrosion resistance of Pb-5%Sb spine alloy. The alloy has been produced by high pressure die casting (HPDC), medium pressure die casting (AS) and low pressure die casting (GS) methods, respectively. The microstructure was characterized by using optical microscopy and scanning electron microscopy (SEM). The hardness was also reported. The corrosion resistance of the spines in 0.5M H2SO4 solution has been analyzed by measuring the weight loss, impedance spectroscopy and the potentiodynamic polarization techniques. It has been found that the spine produced by HPDC has defect-free fine grain structure resulting improvement in hardness and excellent corrosion resistance.

Microstructure characterization and corrosion resistance properties of Pb-Sb alloys for lead acid battery spine produced by different casting methods

PubMed Central

Baig, Muneer; Alam, Mohammad Asif; Alharthi, Nabeel

2018-01-01

The aim of this study is to find out the microstructure, hardness, and corrosion resistance of Pb-5%Sb spine alloy. The alloy has been produced by high pressure die casting (HPDC), medium pressure die casting (AS) and low pressure die casting (GS) methods, respectively. The microstructure was characterized by using optical microscopy and scanning electron microscopy (SEM). The hardness was also reported. The corrosion resistance of the spines in 0.5M H2SO4 solution has been analyzed by measuring the weight loss, impedance spectroscopy and the potentiodynamic polarization techniques. It has been found that the spine produced by HPDC has defect-free fine grain structure resulting improvement in hardness and excellent corrosion resistance. PMID:29668709

Effects of Powder Carrier on the Morphology and Compressive Strength of Iron Foams: Water vs Camphene

NASA Astrophysics Data System (ADS)

Park, Hyeji; Um, Teakyung; Hong, Kicheol; Kang, Jin Soo; Nam, Ho-Seok; Kwon, Kyungjung; Sung, Yung-Eun; Choe, Heeman

2018-06-01

With its well-known popularity in structural applications, considerable attention has recently been paid to iron (Fe) and its oxides for its promising functional applications such as biodegradable implants, water-splitting electrodes, and the anode of lithium-ion batteries. For these applications, iron and its oxides can be even further utilized in the form of porous structures. In order to control the pore size, shape, and amount, we synthesized Fe foams using suspensions of micrometric Fe2O3 powder reduced to Fe via freeze casting in water or liquid camphene as a solvent through sublimation of either ice or camphene under 5 pct H2/Ar gas and sintering. We then compared them and found that the resulting Fe foam using water as a solvent (p = 71.7 pct) showed aligned lamellar macropores replicating ice dendrite colonies, while Fe foam using camphene as a solvent (p = 68.0 pct) exhibited interconnected equiaxed macropores replicating camphene dendrites. For all directions with respect to the loading axis, the compressive behavior of the water-based Fe foam with a directional elongated wall pore structure was anisotropic (11.6 ± 0.9 MPa vs 7.8 ± 0.8 MPa), whereas that of the camphene-based Fe foam with a random round pore structure was nearly isotropic (12.0 ± 1.1 MPa vs 11.6 ± 0.4 MPa).

PRODUCTION OF SLIP CAST CALCIA HOLLOWWARE

DOEpatents

Stoddard, S.D.; Nuckolls, D.E.; Cowan, R.E.

1963-12-31

A method for producing slip cast calcia hollow ware in which a dense calcia grain is suspended in isobutyl acetate or a mixture of tertiary amyl alcohol and o-xylene is presented. A minor amount of triethanolamine and oleic acid is added to the suspension vehicle as viscosity adjusting agents and the suspension is cast in a plaster mold, dried, and fired. (AEC)

Marginal accuracy of nickel chromium copings fabricated by conventional and accelerated casting procedures, produced with ringless and metal ring investment procedures: A comparative in vitro study.

PubMed

Alex, Deepa; Shetty, Y Bharath; Miranda, Glynis Anita; Prabhu, M Bharath; Karkera, Reshma

2015-01-01

Conventional investing and casting techniques are time-consuming and usually requires 2-4 h for completion. Accelerated nonstandard, casting techniques have been reported to achieve similar quality results in significantly less time, namely, in 30-40 min. During casting, it is essential to achieve compensation for the shrinkage of solidifying alloy by investment expansion. The metal casting ring restricts the thermal expansion of investment because the thermal expansion of the ring is lesser than that of the investment. The use of casting ring was challenged with the introduction of the ringless technique. A total of 40 test samples of nickel chromium (Ni-Cr) cast copings were obtained from the patterns fabricated using inlay casting wax. The 20 wax patterns were invested using metal ring and 20 wax patterns were invested using the ringless investment system. Of both the groups, 10 samples underwent conventional casting, and the other 10 underwent accelerated casting. The patterns were casted using the induction casting technique. All the test samples of cast copings were evaluated for vertical marginal gaps at four points on the die employing a stereo optical microscope. The vertical marginal discrepancy data obtained were tabulated. Mean and standard deviations were obtained. Vertical discrepancies were analyzed using analysis of variance and Tukey honestly significantly different. The data obtained were found to be very highly significant (P < 0.001). Mean vertical gap was the maximum for Group II (53.64 μm) followed by Group IV (47.62 μm), Group I (44.83 μm) and Group III (35.35 μm). The Ni-Cr cast copings fabricated with the conventional casting using ringless investment system showed significantly better marginal fit than that of cast copings fabricated from conventional and accelerated casting with metal ring investment and accelerated casting using ringless investment since those copings had shown the least vertical marginal discrepancies among the four methods evaluated in this study.

Dispersion and separation of nanostructured carbon in organic solvents

NASA Technical Reports Server (NTRS)

Evans, Christopher M. (Inventor); Ruf, Herbert J. (Inventor); Landi, Brian J. (Inventor); Raffaelle, Ryne P. (Inventor)

2011-01-01

The present invention relates to dispersions of nanostructured carbon in organic solvents containing alkyl amide compounds and/or diamide compounds. The invention also relates to methods of dispersing nanostructured carbon in organic solvents and methods of mobilizing nanostructured carbon. Also disclosed are methods of determining the purity of nanostructured carbon.

Nanostructured membranes based on polysulfone homopolymers and copolymers

NASA Astrophysics Data System (ADS)

Nunes, Suzana

Polyethersulfone is one of the most successful polymers for membranes with applications varying from seawater desalination to hemodialysis. Their manufacture however is traditionally done by solution casting and phase inversion using solvents, which are now considered negative for the environment. We have been working on the membrane manufacture using ionic liquids as green solvent alternative. Polyethersulfone, and polyetherimide sulfone membranes, as flat-sheet and hollow fibers, were prepared from solutions in different ionic liquids. Thermodynamic and rheological investigation were conducted to optimize the membrane morphology, leading to permeances of 20-65 Lm-2h-1bar-1 useful for instance for separations of peptides with molecular weight in the range of 800 to 3500 gmol-1. We also synthesized block copolymers with polysulfone segments and explored them for membrane preparation with low fouling, high porosity and narrow pore size distribution. The self-assembly of the copolymer in solution, leading to the membrane formation was investigated by cryo electron microscopy, supported by modeling (dissipative particle dynamics). In collaboration with: Dooli Kim, Yihui xie, Burhannudin Sutisna, King Abdullah University of Science and Technology

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

Bryson, Kyle C.; Lobling, Tina I.; Muller, Axel H. E.

Using ternary blends of polystyrene (PS), poly(methyl methacrylate) (PMMA), and Janus particles (JPs) with symmetric PS and PMMA hemispheres, we demonstrate the stabilization of dispersed and bicontinuous phase-separated morphologies by the interfacial adsorption of Janus particles during demixing upon solvent removal. The resulting blend morphology could be varied by changing the blend composition and JP loading. Increasing particle loading decreased the size of phase-separated domains, while altering the mixing ratio of the PS/PMMA homopolymers produced morphologies ranging from PMMA droplets in a PS matrix to PS droplets in a PMMA matrix. Notably, bicontinuous morphologies were obtained at intermediate blend compositions,more » marking the first report of highly continuous domains obtained through demixing in a polymer blend compatibilized by Janus particles. The JPs were found to assemble in a densely packed monolayer at the interface, allowing for the stabilization of bicontinuous morphologies in films above the glass transition temperature by inhibiting coarsening and coalescence of the phase-separated domains. In conclusion, the rate of solvent evaporation from the drop-cast films and the molecular weights of the homopolymers were found to greatly affect blend morphology.« less

PES-Kaolin Mixed Matrix Membranes for Arsenic Removal from Water

PubMed Central

Russo, Francesca; Rezzouk, Lina

2017-01-01

The aim of this work was the fabrication and the characterization of mixed matrix membranes (MMMs) for arsenic (As) removal from water. Membrane separation was combined with an adsorption process by incorporating the kaolin (KT2) Algerian natural clay in polymeric membranes. The effects of casting solution composition was explored using different amounts of polyethersufone (PES) as a polymer, polyvinyl-pyrrolidone (PVP K17) and polyethylene glycol (PEG 200) as pore former agents, N-methyl pyrrolidone (NMP) as a solvent, and kaolin. Membranes were prepared by coupling Non-solvent Induced Phase Separation and Vapour Induced Phase Separation (NIPS and VIPS, respectively). The influence of the exposure time to controlled humid air and temperature was also investigated. The MMMs obtained were characterized in terms of morphology, pore size, porosity, thickness, contact angle and pure water permeability. Adsorption membrane-based tests were carried out in order to assess the applicability of the membranes produced for As removal from contaminated water. Among the investigated kaolin concentrations (ranging from 0 wt % to 5 wt %), a content of 1.25 wt % led to the MMM with the most promising performance. PMID:28974009

Intercalated chitosan/hydroxyapatite nanocomposites: Promising materials for bone tissue engineering applications.

PubMed

Nazeer, Muhammad Anwaar; Yilgör, Emel; Yilgör, Iskender

2017-11-01

Preparation and characterization of chitosan/hydroxyapatite (CS/HA) nanocomposites displaying an intercalated structure is reported. Hydroxyapatite was synthesized through sol-gel process. Formic acid was introduced as a new solvent to obtain stable dispersions of nano-sized HA particles in polymer solution. CS/HA dispersions with HA contents of 5, 10 and 20% by weight were prepared. Self-assembling of HA nanoparticles during the drying of the solvent cast films led to the formation of homogeneous CS/HA nanocomposites. Composite films were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-rays (EDX) analysis, Fourier transform infrared (FTIR) spectroscopy, X-rays diffraction (XRD) analysis and thermogravimetric analysis (TGA). SEM and AFM confirmed the presence of uniformly distributed HA nanoparticles on the chitosan matrix surface. XRD patterns and cross-sectional SEM images showed the formation of layered nanocomposites. Complete degradation of chitosan matrix in TGA experiments, led to the formation of nanoporous 3D scaffolds containing hydroxyapatite, β-tricalcium phosphate and calcium pyrophosphate. CS/HA composites can be considered as promising materials for bone tissue engineering applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Solvent-based and solvent-free characterization of low solubility and low molecular weight polyamides by mass spectrometry: a complementary approach.

PubMed

Barrère, Caroline; Hubert-Roux, Marie; Lange, Catherine M; Rejaibi, Majed; Kebir, Nasreddine; Désilles, Nicolas; Lecamp, Laurence; Burel, Fabrice; Loutelier-Bourhis, Corinne

2012-06-15

Polyamides (PA) belong to the most used classes of polymers because of their attractive chemical and mechanical properties. In order to monitor original PA design, it is essential to develop analytical methods for the characterization of these compounds that are mostly insoluble in usual solvents. A low molecular weight polyamide (PA11), synthesized with a chain limiter, has been used as a model compound and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In the solvent-based approach, specific solvents for PA, i.e. trifluoroacetic acid (TFA) and hexafluoroisopropanol (HFIP), were tested. Solvent-based sample preparation methods, dried-droplet and thin layer, were optimized through the choice of matrix and salt. Solvent-based (thin layer) and solvent-free methods were then compared for this low solubility polymer. Ultra-high-performance liquid chromatography/electrospray ionization (UHPLC/ESI)-TOF-MS analyses were then used to confirm elemental compositions through accurate mass measurement. Sodium iodide (NaI) and 2,5-dihydroxybenzoic acid (2,5-DHB) are, respectively, the best cationizing agent and matrix. The dried-droplet sample preparation method led to inhomogeneous deposits, but the thin-layer method could overcome this problem. Moreover, the solvent-free approach was the easiest and safest sample preparation method giving equivalent results to solvent-based methods. Linear as well as cyclic oligomers were observed. Although the PA molecular weights obtained by MALDI-TOF-MS were lower than those obtained by (1)H NMR and acido-basic titration, this technique allowed us to determine the presence of cyclic and linear species, not differentiated by the other techniques. TFA was shown to induce modification of linear oligomers that permitted cyclic and linear oligomers to be clearly highlighted in spectra. Optimal sample preparation conditions were determined for the MALDI-TOF-MS analysis of PA11, a model of polyamide analogues. The advantages of the solvent-free and solvent-based approaches were shown. Molecular weight determination using MALDI was discussed. Copyright © 2012 John Wiley & Sons, Ltd.

USAXS analysis of concentration-dependent self-assembling of polymer-brush-modified nanoparticles in ionic liquid: [I] concentrated-brush regime

NASA Astrophysics Data System (ADS)

Nakanishi, Yohei; Ishige, Ryohei; Ogawa, Hiroki; Sakakibara, Keita; Ohno, Kohji; Morinaga, Takashi; Sato, Takaya; Kanaya, Toshiji; Tsujii, Yoshinobu

2018-03-01

Using ultra-small angle X-ray scattering (USAXS), we analyzed the higher-order structures of nanoparticles with a concentrated brush of an ionic liquid (IL)-type polymer (concentrated-polymer-brush-modified silica particle; PSiP) in an IL and the structure of the swollen shell layer of PSiP. Homogeneous mixtures of PSiP and IL were successfully prepared by the solvent-casting method involving the slow evaporation of a volatile solvent, which enabled a systematic study over an exceptionally wide range of compositions. Different diffraction patterns as a function of PSiP concentration were observed in the USAXS images of the mixtures. At suitably low PSiP concentrations, the USAXS intensity profile was analyzed using the Percus-Yevick model by matching the contrast between the shell layer and IL, and the swollen structure of the shell and "effective diameter" of the PSiP were evaluated. This result confirms that under sufficiently low pressures below and near the liquid/crystal-threshold concentration, the studied PSiP can be well described using the "hard sphere" model in colloidal science. Above the threshold concentration, the PSiP forms higher-order structures. The analysis of diffraction patterns revealed structural changes from disorder to random hexagonal-closed-packing and then face-centered-cubic as the PSiP concentration increased. These results are discussed in terms of thermodynamically stable "hard" and/or "semi-soft" colloidal crystals, wherein the swollen layer of the concentrated polymer brush and its structure play an important role.

The Effects of Casting Porosity on the Tensile Behavior of Investment Cast 17-4PH Stainless Steel

NASA Astrophysics Data System (ADS)

Susan, D. F.; Crenshaw, T. B.; Gearhart, J. S.

2015-08-01

The effect of casting porosity on the mechanical behavior of investment cast 17-4PH stainless steel was studied as well as the effect of heat treatment on the alloy's sensitivity to casting defects. Interdendritic porosity, formed during solidification and shrinkage of the alloy, reduces the yield strength and ultimate tensile strength roughly in proportion to the reduction in load bearing cross-section. The effects of casting porosity on ductility (% strain, % reduction in area) are more severe, in agreement with research on other alloy systems. In this study, 10% porosity reduced the ductility of 17-4PH stainless steel by almost 80% for the high-strength H925 condition. Tensile testing at -10°C (263 K) further reduces the alloy ductility with and without pores present. In the lower strength H1100 condition, the ductility is higher than the H925 condition, as expected, and somewhat less sensitive to porosity. By measuring the area % porosity on the fracture surface of tensile specimens, the trend in failure strain versus area % porosity was obtained and analyzed using two methods: an empirical approach to determine an index of defect susceptibility with a logarithmic fit and an analytical approach based on the constitutive stress-strain behavior and critical strain concentration in the vicinity of the casting voids. The applicability of the second method depends on the amount of non-uniform strain (necking) and, as such, the softer H1100 material did not correlate well to the model. The behavior of 17-4PH was compared to previous work on cast Al alloys, Mg alloys, and other cast materials.

Casting technology for manufacturing metal rods from simulated metallic spent fuels

NASA Astrophysics Data System (ADS)

Leeand, Y. S.; Lee, D. B.; Kim, C. K.; Shin, Y. J.; Lee, J. H.

2000-09-01

A uranium metal rod 13.5 mm in diameter and 1,150 mm long was produced from simulated metallic spent fuels with advanced casting equipment using the directional-solidification method. A vacuum casting furnace equipped with a four-zone heater to prevent surface oxidation and the formation of surface shrinkage holes was designed. By controlling the axial temperature gradient of the casting furnace, deformation by the surface shrinkage phenomena was diminished, and a sound rod was manufactured. The cooling behavior of the molten uranium was analyzed using the computer software package MAGMAsoft.

Biomimetic Materials by Freeze Casting

NASA Astrophysics Data System (ADS)

Porter, Michael M.; Mckittrick, Joanna; Meyers, Marc A.

2013-06-01

Natural materials, such as bone and abalone nacre, exhibit exceptional mechanical properties, a product of their intricate microstructural organization. Freeze casting is a relatively simple, inexpensive, and adaptable materials processing method to form porous ceramic scaffolds with controllable microstructural features. After infiltration of a second polymeric phase, hybrid ceramic-polymer composites can be fabricated that closely resemble the architecture and mechanical performance of natural bone and nacre. Inspired by the narwhal tusk, magnetic fields applied during freeze casting can be used to further control architectural alignment, resulting in freeze-cast materials with enhanced mechanical properties.

Method to prevent/mitigate steam explosions in casting pits

DOEpatents

Taleyarkhan, R.P.

1996-12-24

Steam explosions can be prevented or mitigated during a metal casting process by the placement of a perforated flooring system in the casting pit. An upward flow of compressed gas through this perforated flooring system is introduced during the casting process to produce a buffer layer between any spilled molten metal and the cooling water in the reservoir. This buffer layer provides a hydrodynamic layer which acts to prevent or mitigate steam explosions resulting from hot, molten metal being spilled into or onto the cooling water. 3 figs.

Investigation of the Effect of Mixing Methods and Chemical Treatments on the Conductivity of the CNT/PLA Based Composites

NASA Astrophysics Data System (ADS)

Talwar, Brijpal Singh

The growing popularity of Poly lactic acid (PLA) is mainly due to its biocompatibility, good mechanical properties, and its synthesis from renewable resources. PLA can be compounded with electrically conductive fillers (e.g., carbon nanotubes (CNTs)) to form conductive polymer composites (CPCs). These fillers provide conductive functionality to the composite material by forming percolation paths. Featuring very low weight densities, CPCs have the potential to replace metals in the electronic industry, if they exhibit similar electrical conductivities to that of the metals. The current challenges being faced during the mixing of CNTs in the polymer matrix are: formation of aggregates due to strong van der Waals forces and breakage of CNTs during dispersion. In this study, we compare: (1) two fabrication methods to create CPCs (i.e., solution mixing by sonication and melt extrusion) (2) effect of various CNT functionalization techniques (i.e., acid and plasma treatments) on the conductivity of CPCs and (3) effect of using binding molecules like para-phenylenediamine, that act as bridges in between the CNTs in the CPCs and its effect on the conductivity of CPCs. Such conductive composite materials find widespread technological applications which either require, or could benefit from, the ability to pattern micro-sized features in two-dimensional (2D) and three-dimensional (3D) architectures. Direct-write fabrication technique is used to realise these printed patterns, using the CPC solution as ink. First, the composites comprising of 30% PLA by weight in Dichloromethane (DCM) and CNTs in different concentrations (up to 5wt. %) are fabricated using a two-step sonication method (i.e., dissolving PLA in DCM and then dispersing the CNTs in this polymer solution). Second, CPCs are fabricated using a twin screw micro extruder operating at 180°C. To verify the effects of functionalization of the CNTs on the conductivity of composites, the CNTs are functionalized by three methods: HNO3 acid functionalization, 3:1 ratio HNO 3 + H2SO4 acid (stronger) functionalization and N2 plasma functionalization. To check the effect of amine binding molecules, HNO3 acid functionalized CNTs are treated with a mixture of para-phenylenediamine and aniline in an acidic solution. These chemically treated CNTs are then mixed with PLA to form composites. CPC fibers are drawn using the solvent-cast printing method. These fibers are tested for their electrical conductivity using the two-probe resistivity measurement method. Maximum electrical conductivity was observed in the 5wt. % CNT concentration samples at 3.97 S/m and 25.16 S/m for CPC fibers obtained via the solution blend and the extrusion methods, respectively. In the case of the functionalized CNTs, conductivity measurements show a negative effect of functionalization on the electrical properties of the CPC. While, the amine treated CNT/PLA CPC fibers show better conductivity at 4.2 S/m when compared to the untreated CNT/PLA samples manufactured using the solution mixing method. Finally, one-dimensional (1D) structures like fibres and 2D, 3D structures like single and multi-layer scaffolds were fabricated using the solvent-cast printing technique with the above manufactured CPC solutions in DCM as inks. Such conductive microstructures find their application in the electronic industry and in micro-scale systems such as pollution detection in natural environments, tissue engineering, mechanical sensors and smart devices.

Fibreglass Total Contact Casting, Removable Cast Walkers, and Irremovable Cast Walkers to Treat Diabetic Neuropathic Foot Ulcers: A Health Technology Assessment

PubMed Central

Costa, Vania; Tu, Hong Anh; Wells, David; Weir, Mark; Holubowich, Corinne; Walter, Melissa

2017-01-01

Background Diabetic neuropathic foot ulcers are a risk factor for lower leg amputation. Many experts recommend offloading with fibreglass total contact casting, removable cast walkers, and irremovable cast walkers as a way to treat these ulcers. Methods We completed a health technology assessment, which included an evaluation of clinical benefits and harms, value for money, and patient preferences for offloading devices. We performed a systematic literature search on August 17, 2016, to identify randomized controlled trials that compared fibreglass total contact casting, removable cast walkers, and irremovable cast walkers with other treatments (offloading or non-offloading) in patients with diabetic neuropathic foot ulcers. We developed a decision-analytic model to assess the cost-effectiveness of fibreglass total contact casting, removable cast walkers, and irremovable cast walkers, and we conducted a 5-year budget impact analysis. Finally, we interviewed people with diabetes who had lived experience with foot ulcers, asking them about the different offloading devices and the factors that influenced their treatment choices. Results We identified 13 randomized controlled trials. The evidence suggests that total contact casting, removable cast walkers, and irremovable cast walkers are beneficial in the treatment of neuropathic, noninfected foot ulcers in patients with diabetes but without severe peripheral arterial disease. Compared to removable cast walkers, ulcer healing was improved with total contact casting (moderate quality evidence; risk difference 0.17 [95% confidence interval 0.00–0.33]) and irremovable cast walkers (low quality evidence; risk difference 0.21 [95% confidence interval 0.01–0.40]). We found no difference in ulcer healing between total contact casting and irremovable cast walkers (low quality evidence; risk difference 0.02 [95% confidence interval −0.11–0.14]). The economic analysis showed that total contact casting and irremovable cast walkers were less expensive and led to more health outcome gains (e.g., ulcers healed and quality-adjusted life-years) than removable cast walkers. Irremovable cast walkers were as effective as total contact casting and were associated with lower costs. The 5-year budget impact of funding total contact casting, removable cast walkers, and irremovable cast walkers (device costs only at 100% access) would be $17 to $20 million per year. The patients we interviewed felt that wound healing was improved with total contact casting than with removable cast walkers, but that removable cast walkers were more convenient and came with a lower cost burden. They reported no experience or familiarity with irremovable cast walkers. Conclusions Ulcer healing improved with total contact casting, irremovable cast walkers, and removable cast walkers, but total contact casting and irremovable cast walkers had higher rates of ulcer healing than removable cast walkers. Increased access to offloading devices could result in cost savings for the health system because of fewer amputations. Patients with diabetic foot ulcers reported a preference for total contact casting over removable cast walkers, largely because they perceived wound healing to be improved with total contact casting. However, cost, comfort, and convenience are concerns for patients. PMID:28989556

Software Analytical Instrument for Assessment of the Process of Casting Slabs

NASA Astrophysics Data System (ADS)

Franěk, Zdeněk; Kavička, František; Štětina, Josef; Masarik, Miloš

2010-06-01

The paper describes the original proposal of ways of solution and function of the program equipment for assessment of the process of casting slabs. The program system LITIOS was developed and implemented in EVRAZ Vitkovice Steel Ostrava on the equipment of continuous casting of steel (further only ECC). This program system works on the data warehouse of technological parameters of casting and quality parameters of slabs. It enables an ECC technologist to analyze the course of casting melt and with using statistics methods to set the influence of single technological parameters on the duality of final slabs. The system also enables long term monitoring and optimization of the production.

The analysis of composite properties reinforced with particles from palm oil industry waste produced by casting methods

NASA Astrophysics Data System (ADS)

Tugiman; Ariani, F.; Taher, F.; Hasibuan, M. S.; Suprianto

2017-12-01

Palm oil processing industries are very attractive because they offer plenty products with high economic value. The CPO factory processes not only produces crude palm oil but also generates fly ash (FA) particles waste in its final process. The purpose of this investigation to analyze and increase the benefits of particles as reinforcement materials for fabricating aluminum matrix composites (AMC’s) by different casting route. Stirring, centrifugal and squeeze casting method was conducted in this study. Further, the chemical composition of FA particles, densities and mechanical properties have been analyzed. The characteristics of composite material were investigated using an Optical microscope, scanning electron microscope (SEM), hardness (Brinell), impact strength (Charpy). The pin on disc method was used to measure the wear rate. The results show that SiO2, Fe2O3, and Al2O3 are the main compounds of fly ash particles. These particles enhanced the hardness and reduce wear resistance of aluminum matrix composites. The squeeze method gives better results than stir and centrifugal casting.

A mathematical model of the heat and fluid flows in direct-chill casting of aluminum sheet ingots and billets

NASA Astrophysics Data System (ADS)

Mortensen, Dag

1999-02-01

A finite-element method model for the time-dependent heat and fluid flows that develop during direct-chill (DC) semicontinuous casting of aluminium ingots is presented. Thermal convection and turbulence are included in the model formulation and, in the mushy zone, the momentum equations are modified with a Darcy-type source term dependent on the liquid fraction. The boundary conditions involve calculations of the air gap along the mold wall as well as the heat transfer to the falling water film with forced convection, nucleate boiling, and film boiling. The mold wall and the starting block are included in the computational domain. In the start-up period of the casting, the ingot domain expands over the starting-block level. The numerical method applies a fractional-step method for the dynamic Navier-Stokes equations and the “streamline upwind Petrov-Galerkin” (SUPG) method for mixed diffusion and convection in the momentum and energy equations. The modeling of the start-up period of the casting is demonstrated and compared to temperature measurements in an AA1050 200×600 mm sheet ingot.

Characterization of HEM silicon for solar cells. [Heat Exchanger Method

NASA Technical Reports Server (NTRS)

Dumas, K. A.; Khattak, C. P.; Schmid, F.

1981-01-01

The Heat Exchanger Method (HEM) is a promising low-cost ingot casting process for material used for solar cells. This is the only method that is capable of casting single crystal ingots with a square cross section using a directional solidification technique. This paper describes the chemical, mechanical and electrical properties of the HEM silicon material as a function of position within the ingot.

Distal femoral osteotomy in genovalgum: internal fixation with blade plate versus casting.

PubMed

Makhmalbaf, Hadi; Moradi, Ali; Ganji, Saeid

2014-10-01

To compare the results of two different ways of distal femoral osteotomy stabilization in patients suffering from genuvalgum: internal fixation with plate, and casting. In a non-randomized prospective study, after distal femoral osteotomy with the zigzag method, patients were divided into two groups: long leg casting, and internal fixation with blade plate. For all patients, questionnaires were filled to obtain data. Information such as range of motion, tibiofemoral anatomical angle and complications were recorded. 38 knees with valgus deformity underwent distal femoral supracondylar osteotomy. (8 with plaster cast and 30 with internal fixation using a blade plate). Preoperative range of motion was 129±6° and six months later it was 120±14°. The preoperative tibiofemoral angle was 32±6°; postoperative tibiofemoral angles were 3±3°, 6±2°, and 7±3° just after operation, six months, and two years later, respectively. Although this angle was greater among the group stabilized with a cast, this difference was not statistically significant. In postoperative complications, over-correction was found in five, recorvatom deformity in one, knee stiffness in three and superficial wound infection was recorded in three knees. There is no prominent difference in final range of motion and alignment whether fixation is done with casting or internal fixation. However, the complication rate seems higher in the casting method.

[Preparation and characterization of polyhydroxyalkanoate bioplastics with antibacterial activity].

PubMed

Lou, Qiuli; Ma, Yiming; Che, Xuemei; Zhong, Jin; Sun, Xiaoxia; Zhang, Haoqian

2016-08-25

Polyhydroxyalkanoates (PHAs), as a novel class of biopolymer, are attracting more attention due to their diverse material properties and environment-independent biodegradability. Here we report the preparation of PHA exhibiting efficient antibacterial activity by embedding Nisin, a food additive generally recognized as safe, into poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx), a type of PHA with high biocompatibility. We first prepared Nisin-containing PHBHHx films using solvent casting method. Confocal laser scanning microscopy analysis showed that a well-mixed integrated structure of the films with an even distribution of the Nisin particles in the PHBHHx matrices. Then the antimicrobial activity of PHBHHx/Nisin films against Micrococcus luteus was quantified on agar plate by measuring the size of inhibition zone. Cultivation in liquid media further confirmed the releasing of Nisin from the films and the long-time antibacterial activity. Results showed that the threshold of Nisin concentration for long-time and effective inhibition against bacteria growth is 25 μg/g. These results altogether establish a technological foundation for the application of PHA in biomedicine and food industry.

Growth of Solid Solution Crystals

NASA Technical Reports Server (NTRS)

Lehoczky, S. L.; Szofran, F. R.; Holland, L. R.

1985-01-01

The major objective of this program is to determine the conditions under which single crystals of solid solutions can be grown from the melt in a Bridgman configuration with a high degree of chemical homogeneity. The central aim is to assess the role of gravity in the growth process and to explore the possible advantages for growth in the absence of gravity. The alloy system being investigated is the solid solution semiconductor with x-values appropriate for infrared detector applications in Hg sub (1-x) Cd sub x Te the 8 to 14 micro m wavelength region. Both melt and Te-solvent growth are being considered. The study consists of an extensive ground-based experimental and theoretical research effort followed by flight experimentation where appropriate. Experimental facilities have been established for the purification, casting, and crystal growth of the alloy system. Facilities have been also established for the metallurgical, compositional, electric and optical characterization of the alloys. Crystals are being grown by the Bridgman-Stockbarger method and are analyzed by various experimental techniques to evaluate the effects of growth conditions on the longitudinal and radial compositional variations and defect densities in the crystals.

Fabrication of a Bioactive, PCL-based "Self-fitting" Shape Memory Polymer Scaffold.

PubMed

Nail, Lindsay N; Zhang, Dawei; Reinhard, Jessica L; Grunlan, Melissa A

2015-10-23

Tissue engineering has been explored as an alternative strategy for the treatment of critical-sized cranio-maxillofacial (CMF) bone defects. Essential to the success of this approach is a scaffold that is able to conformally fit within an irregular defect while also having the requisite biodegradability, pore interconnectivity and bioactivity. By nature of their shape recovery and fixity properties, shape memory polymer (SMP) scaffolds could achieve defect "self-fitting." In this way, following exposure to warm saline (~60 ºC), the SMP scaffold would become malleable, permitting it to be hand-pressed into an irregular defect. Subsequent cooling (~37 ºC) would return the scaffold to its relatively rigid state within the defect. To meet these requirements, this protocol describes the preparation of SMP scaffolds prepared via the photochemical cure of biodegradable polycaprolactone diacrylate (PCL-DA) using a solvent-casting particulate-leaching (SCPL) method. A fused salt template is utilized to achieve pore interconnectivity. To realize bioactivity, a polydopamine coating is applied to the surface of the scaffold pore walls. Characterization of self-fitting and shape memory behaviors, pore interconnectivity and in vitro bioactivity are also described.

Rheological and structural characterisation of film-forming solutions and biodegradable edible film made from kefiran as affected by various plasticizer types.

PubMed

Ghasemlou, Mehran; Khodaiyan, Faramarz; Oromiehie, Abdulrasoul

2011-11-01

The rheological properties of kefiran film-forming solutions, as well as the structural characterisation of the resulting films, were investigated as a function of various plasticizer types. The behaviours of the storage (G') and loss (G″) moduli as a function of frequency were typical of gel-like material, with the G' higher than the G″. Kefiran-based films, which may find application as edible films, were prepared by a casting and solvent-evaporation method. Possible interaction between the adjacent chains in the kefiran polymer and various plasticizers was proven by Fourier-transform infrared spectroscopy (FT-IR). The crystallinity of plasticized kefiran film was also analysed using X-ray diffraction (XRD); this revealed an amorphous-crystalline structure. These results were explained by the film's microstructure, which was analysed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The present study has helped determine possible interactions of kefiran, plasticizer and water molecules in determining film properties. Copyright © 2011 Elsevier B.V. All rights reserved.

Shape-memory effect by specific biodegradable polymer blending for biomedical applications.

PubMed

Cha, Kook Jin; Lih, Eugene; Choi, Jiyeon; Joung, Yoon Ki; Ahn, Dong Jun; Han, Dong Keun

2014-05-01

Specific biodegradable polymers having shape-memory properties through "polymer-blend" method are investigated and their shape-switching in body temperature (37 °C) is characterized. Poly(L-lactide-co-caprolactone) (PLCL) and poly(L-lactide-co-glycolide) (PLGA) are dissolved in chloroform and the films of several blending ratios of PLCL/PLGA are prepared by solvent casting. The shape-memory properties of films are also examined using dynamic mechanical analysis (DMA). Among the blending ratios, the PLCL50/PLGA50 film shows good performance of shape-fixity and shape-recovery based on glass transition temperature. It displays that the degree of shape recovery is 100% at 37 °C and the shape recovery proceeds within only 15 s. In vitro biocompatibility studies are shown to have good blood compatibility and cytocompatibility for the PLCL50/PLGA50 films. It is expected that this blended biodegradable polymer can be potentially used as a material for blood-contacting medical devices such as a self-expended vascular polymer stents and vascular closure devices in biomedical applications. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ion-Conductive and Thermal Properties of a Synergistic Poly(ethylene carbonate)/Poly(trimethylene carbonate) Blend Electrolyte.

PubMed

Li, Zhenguang; Mogensen, Ronnie; Mindemark, Jonas; Bowden, Tim; Brandell, Daniel; Tominaga, Yoichi

2018-05-11

Electrolytes comprising poly(ethylene carbonate) (PEC)/poly(trimethylene carbonate) (PTM C) with lithium bis(trifluoromethane sulfonyl)imide (LiTFSI) are prepared by a simple solvent casting method. Although PEC and PTMC have similar chemical structures, they are immiscible and two glass transitions are present in the differential scanning calorimetry (DSC) measurements. Interestingly, these two polymers change to miscible blends with the addition of LiTFSI, and the ionic conductivity increases with increasing lithium salt concentration. The optimum composition of the blend electrolyte is achieved at PEC 6 PTMC 4 , with a conductivity as high as 10 -6 S cm -1 at 50 °C. This value is greater than that for single PEC- and PTMC-based electrolytes. Moreover, the thermal stability of the blend-based electrolytes is improved as compared to PEC-based electrolytes. It is clear that the interaction between CO groups and Li + gives rise to a compatible amorphous phase of PEC and PTMC. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Synthesis of solution-processable poly(3,4 propylenedioxythiophene) nanobelts for electrochromic device applications

NASA Astrophysics Data System (ADS)

Raghavan, Siju Cherikkattil; Shivaprakash, N. Channegowda; Sindhu, Sukumaran Nair

2017-11-01

A new derivative of di-4-isopropyl benzyl substituted propylenedioxythiophene (ProDOT-IPBz2) monomer was synthesized and its resultant polymer was prepared by chemical and electrochemical methods. The chemical polymerization was carried out in a hexane/water reverse microemulsion system using sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as self-assembling template. Chemically synthesized PProDOT-IPBz2 was formed as thin nanobelts with high aspect ratio (3:100), and it was found to be soluble in common organic solvents. The electrochemical and electrochromic (EC) properties of PProDOT-IPBz2 films were studied and it was found that PProDOT-IPBz2 films showed high transparency at oxidized state (+1.0 V) and dark purple color formed at reduced state (-1.0 V). The color contrast of solution cast film was calculated to be 37% T at 550 nm, however electropolymerized PProDOT-IPBz2 film exhibited a color contrast of 48% at 550 nm with switching speed of ∼1 s, and the coloration efficiency was calculated to be 305 cm2C-1.

Synergistic reinforcing effect of TiO2 and montmorillonite on potato starch nanocomposite films: Thermal, mechanical and barrier properties.

PubMed

Oleyaei, Seyed Amir; Almasi, Hadi; Ghanbarzadeh, Babak; Moayedi, Ali Akbar

2016-11-05

In this study, ternary potato starch (PS) bionanocomposite films containing two types of nanoparticles, sodium montmorillonite (MMT), one-dimensional (1D) clay platelets, (3 and 5wt%) and TiO2, three-dimensional (3D) nanospheres, (0.5, 1 and 2wt%), are prepared using solvent casting method. X-ray diffraction (XRD) test confirms the completely exfoliated structure formed in the PS-MMT nanocomposites containing 3 and 5% MMT. The success of the formation of new hydrogen bonds between the hydroxyl groups of starch and nanofillers is confirmed by Fourier transform infrared (FTIR) spectroscopy. Tensile strength (TS), elongation at break (EB), glass transition temperature (Tg), and melting point (Tm) of the films are also enhanced after MMT and TiO2 incorporation. The water vapor permeability (WVP) and the visible, UVA, UVB and UVC lights transmittance decreases upon TiO2 and MMT content increasing. Generally, a synergistic effect is observed between MMT and TiO2 at lower concentrations of MMT. Copyright © 2016 Elsevier Ltd. All rights reserved.

Oriented MOF-polymer Composite Nanofiber Membranes for High Proton Conductivity at High Temperature and Anhydrous Condition

PubMed Central

Wu, Bin; Pan, Jiefeng; Ge, Liang; Wu, Liang; Wang, Huanting; Xu, Tongwen

2014-01-01

The novel oriented electrospun nanofiber membrane composed of MOFs and SPPESK has been synthesized for proton exchange membrane fuel cell operating at high temperature and anhydrous conditions. It is clear that the oriented nanofiber membrane displays the higher proton conductivity than that of the disordered nanofiber membrane or the membrane prepared by conventional solvent-casting method (without nanofibers). Nanofibers within the membranes are significantly oriented. The proton conductivity of the oriented nanofiber membrane can reach up to (8.2 ± 0.16) × 10−2 S cm−1 at 160°C under anhydrous condition for the highly orientation of nanofibers. Moreover, the oxidative stability and resistance of methanol permeability of the nanofibers membrane are obviously improved with an increase in orientation of nanofibers. The observed methanol permeability of 0.707 × 10−7 cm2 s−1 is about 6% of Nafion-115. Consequently, orientated nanofibers membrane is proved to be a promising material as the proton exchange membrane for potential application in direct methanol fuel cells. PMID:25082522

Fabrication of compact and stable perovskite films with optimized precursor composition in the fast-growing procedure

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

Liu, Tanghao; Zhou, Yuanyuan; Hu, Qin

The fast-growing procedure (FGP) provides a simple, high-yield and lead (Pb)-release free method to prepare perovskite films. In the FGP, the ultra-dilute perovskite precursor solution is drop-cast onto a hot (~240 degrees C) substrate, where a perovskite film grows immediately accompanied by the rapid evaporation of the host solvent. In this process, all the raw materials in the precursor solution are deposited into the final perovskite film. The potential pollution caused by Pb can be significantly reduced. Properties of the FGP-processed perovskite films can be modulated by the precursor composition. While CH3NH3Cl (MACl) affects the crystallization process and leads tomore » full surface coverage, CH(NH2)2I (FAI) enhances the thermal stability of the film. Based on the optimized precursor composition of PbI2(1-x)FAI xMACl, x=0.75, FGP-processed planar heterojunction perovskite solar cells exhibit power conversion efficiencies (PCEs) exceeding 15% with suppressed hysteresis and excellent reproducibility.« less

Process for reducing beta activity in uranium

DOEpatents

Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

1986-10-07

This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

Process for reducing beta activity in uranium

DOEpatents

Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

1986-01-01

This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

Process for reducing beta activity in uranium

DOEpatents

Briggs, G.G.; Kato, T.R.; Schonegg, E.

1985-04-11

This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

Microstructure and Corrosion Characterization of Squeeze Cast AM50 Magnesium Alloys

NASA Astrophysics Data System (ADS)

Sachdeva, Deepika; Tiwari, Shashank; Sundarraj, Suresh; Luo, Alan A.

2010-12-01

Squeeze casting of magnesium alloys potentially can be used in lightweight chassis components such as control arms and knuckles. This study documents the microstructural analysis and corrosion behavior of AM50 alloys squeeze cast at different pressures between 40 and 120 MPa and compares them with high-pressure die cast (HPDC) AM50 alloy castings and an AM50 squeeze cast prototype control arm. Although the corrosion rates of the squeeze cast samples are slightly higher than those observed for the HPDC AM50 alloy, the former does produce virtually porosity-free castings that are required for structural applications like control arms and wheels. This outcome is extremely encouraging as it provides an opportunity for additional alloy and process development by squeeze casting that has remained relatively unexplored for magnesium alloys compared with aluminum. Among the microstructural parameters analyzed, it seems that the β-phase interfacial area, indicating a greater degree of β network, leads to a lower corrosion rate. Weight loss was the better method for determining corrosion behavior in these alloys that contain a large fraction of second phase, which can cause perturbations to an overall uniform surface corrosion behavior.

Properties of a hybrid plaster-fibreglass cast

PubMed Central

Charles, Mark N.; Yen, David

2000-01-01

Objective To examine the suitability of a plaster-fibreglass hybrid cast for orthopedic applications, comparing them to plaster of Paris (POP) and fibreglass constructs. Method Groups of 10 standardized hybrid, POP and fibreglass casts were studied. An Instron servo-hydraulic system was used to test the casts in 3-point bending and shear. Outcome measures Strength, stiffness, weight, thickness and cost of the 3 types of cast, and shear strength at the interface between the POP and fibreglass in the hybrid casts. Results The hybrid casts were twice as strong as the POP constructs, were stiffer and weighed 14% less but were thicker and cost 2.5 times more. They were almost as strong as and less than half the cost of the fibreglass constructs but were thicker, not as stiff, and weighed 42% more. The shear strength of the POP–fibreglass interface in the hybrid casts was higher than the 3-point bending strength of this construct by a factor of 3. Conclusions Plaster-fibreglass hybrid casts should be considered for orthopedic use on the basis of their strength, stiffness, weight and cost, combined with their acknowledged advantages of good moulding ability and water resistance. PMID:11045095

Improving the collection of knowledge, attitude and practice data with community surveys: a comparison of two second-stage sampling methods.

PubMed

Davis, Rosemary H; Valadez, Joseph J

2014-12-01

Second-stage sampling techniques, including spatial segmentation, are widely used in community health surveys when reliable household sampling frames are not available. In India, an unresearched technique for household selection is used in eight states, which samples the house with the last marriage or birth as the starting point. Users question whether this last-birth or last-marriage (LBLM) approach introduces bias affecting survey results. We conducted two simultaneous population-based surveys. One used segmentation sampling; the other used LBLM. LBLM sampling required modification before assessment was possible and a more systematic approach was tested using last birth only. We compared coverage proportions produced by the two independent samples for six malaria indicators and demographic variables (education, wealth and caste). We then measured the level of agreement between the caste of the selected participant and the caste of the health worker making the selection. No significant difference between methods was found for the point estimates of six malaria indicators, education, caste or wealth of the survey participants (range of P: 0.06 to >0.99). A poor level of agreement occurred between the caste of the health worker used in household selection and the caste of the final participant, (Κ = 0.185), revealing little association between the two, and thereby indicating that caste was not a source of bias. Although LBLM was not testable, a systematic last-birth approach was tested. If documented concerns of last-birth sampling are addressed, this new method could offer an acceptable alternative to segmentation in India. However, inter-state caste variation could affect this result. Therefore, additional assessment of last birth is required before wider implementation is recommended. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2013; all rights reserved.

Three-dimensional accuracy of different correction methods for cast implant bars

PubMed Central

Kwon, Ji-Yung; Kim, Chang-Whe; Lim, Young-Jun; Kwon, Ho-Beom

2014-01-01

PURPOSE The aim of the present study was to evaluate the accuracy of three techniques for correction of cast implant bars. MATERIALS AND METHODS Thirty cast implant bars were fabricated on a metal master model. All cast implant bars were sectioned at 5 mm from the left gold cylinder using a disk of 0.3 mm thickness, and then each group of ten specimens was corrected by gas-air torch soldering, laser welding, and additional casting technique. Three dimensional evaluation including horizontal, vertical, and twisting measurements was based on measurement and comparison of (1) gap distances of the right abutment replica-gold cylinder interface at buccal, distal, lingual side, (2) changes of bar length, and (3) axis angle changes of the right gold cylinders at the step of the post-correction measurements on the three groups with a contact and non-contact coordinate measuring machine. One-way analysis of variance (ANOVA) and paired t-test were performed at the significance level of 5%. RESULTS Gap distances of the cast implant bars after correction procedure showed no statistically significant difference among groups. Changes in bar length between pre-casting and post-correction measurement were statistically significance among groups. Axis angle changes of the right gold cylinders were not statistically significance among groups. CONCLUSION There was no statistical significance among three techniques in horizontal, vertical and axial errors. But, gas-air torch soldering technique showed the most consistent and accurate trend in the correction of implant bar error. However, Laser welding technique, showed a large mean and standard deviation in vertical and twisting measurement and might be technique-sensitive method. PMID:24605205

The use of porcine corrosion casts for teaching human anatomy.

PubMed

Eberlova, Lada; Liska, Vaclav; Mirka, Hynek; Tonar, Zbynek; Haviar, Stanislav; Svoboda, Milos; Benes, Jan; Palek, Richard; Emingr, Michal; Rosendorf, Jachym; Mik, Patrik; Leupen, Sarah; Lametschwandtner, Alois

2017-09-01

In teaching and learning human anatomy, anatomical autopsy and prosected specimens have always been indispensable. However, alternative methods must often be used to demonstrate particularly delicate structures. Corrosion casting of porcine organs with Biodur E20 ® Plus is valuable for teaching and learning both gross anatomy and, uniquely, the micromorphology of cardiovascular, respiratory, digestive, and urogenital systems. Assessments of casts with a stereomicroscope and/or scanning electron microscope as well as highlighting cast structures using color coding help students to better understand how the structures that they have observed as two-dimensional images actually exist in three dimensions, and students found using the casts to be highly effective in their learning. Reconstructions of cast hollow structures from (micro-)computed tomography scans and videos facilitate detailed analyses of branching patterns and spatial arrangements in cast structures, aid in the understanding of clinically relevant structures and provide innovative visual aids. The casting protocol and teaching manual we offer can be adjusted to different technical capabilities and might also be found useful for veterinary or other biological science classes. Copyright © 2017 Elsevier GmbH. All rights reserved.

Vascular corrosion casting technique steps.

PubMed

Verli, Flaviana Dornela; Rossi-Schneider, Tissiana Raquel; Schneider, Felipe Luís; Yurgel, Liliane Soares; de Souza, Maria Antonieta Lopes

2007-01-01

The vascular corrosion casting technique produces a replica of vascular beds of normal or pathological tissues. Once associated with scanning electron microscopy (SEM), this technique provides details of the three-dimensional anatomic arrangement of the vascular replica, which is the main advantage of this method. The present study is intended to describe the steps of the vascular corrosion casting technique and the different ways to perform them. them.

Vascular Corrosion Casting: Review of Advantages and Limitations in the Application of Some Simple Quantitative Methods.

PubMed

Hossler, Fred E.; Douglas, John E.

2001-05-01

Vascular corrosion casting has been used for about 40 years to produce replicas of normal and abnormal vasculature and microvasculature of various tissues and organs that could be viewed at the ultrastructural level. In combination with scanning electron microscopy (SEM), the primary application of corrosion casting has been to describe the morphology and anatomical distribution of blood vessels in these tissues. However, such replicas should also contain quantitative information about that vasculature. This report summarizes some simple quantitative applications of vascular corrosion casting. Casts were prepared by infusing Mercox resin or diluted Mercox resin into the vasculature. Surrounding tissues were removed with KOH, hot water, and formic acid, and the resulting dried casts were observed with routine SEM. The orientation, size, and frequency of vascular endothelial cells were determined from endothelial nuclear imprints on various cast surfaces. Vascular volumes of heart, lung, and avian salt gland were calculated using tissue and resin densities, and weights. Changes in vascular volume and functional capillary density in an experimentally induced emphysema model were estimated from confocal images of casts. Clearly, corrosion casts lend themselves to quantitative analysis. However, because blood vessels differ in their compliances, in their responses to the toxicity of casting resins, and in their response to varying conditions of corrosion casting procedures, it is prudent to use care in interpreting this quantitative data. Some of the applications and limitations of quantitative methodology with corrosion casts are reviewed here.

Method for removing contaminants from plastic resin

DOEpatents

Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

2008-12-09

A resin recycling method that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The method includes receiving the resin in container form. The containers are then ground into resin particles. The particles are exposed to a solvent, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. After separating the particles and the resin, a solvent removing agent is used to remove any residual solvent remaining on the resin particles after separation.

Comparison of Growing Rod Instrumentation Versus Serial Cast Treatment for Early-Onset Scoliosis.

PubMed

Johnston, Charles E; McClung, Anna M; Thompson, George H; Poe-Kochert, Connie; Sanders, James O

2013-09-01

A comparison of 2 methods of early-onset scoliosis treatment using radiographic measures and complication rates. To determine whether a delaying tactic (serial casting) has comparable efficacy to a surgical method (insertion of growing rod instrumentation [GRI]) in the initial phase of early-onset deformity management. Serial casts are used in experienced centers to delay operative management of curves of surgical magnitude (greater than 50°) in children up to age 6 years. A total of 27 casted patients from 3 institutions were matched with 27 patients from a multicenter database according to age (within 6 months of each other), curve magnitude (within 10° of each other), and diagnosis. Outcomes were compared according to major curve magnitude, spine length (T1-S1), duration and number of treatment encounters, and complications. There was no difference in age (5.5 years) or initial curve magnitude (65°) between groups, which reflects the accuracy of the matching process. Six pairs of patients had neuromuscular diagnoses, 11 had idiopathic deformities, and 10 had syndromic scoliosis. Growing rod instrumentation patients had smaller curves (45.9° vs. 64.9°; p = .002) at follow-up, but there was no difference in absolute spine length (GRI = 32.0 cm; cast = 30.6 cm; p = .26), even though GRI patients had been under treatment for a longer duration (4.5 vs. 2.4 years; p < .0001) and had undergone a mean of 5.5 lengthenings compared with 4.0 casts. Growing rod instrumentation patients had a 44% complication rate, compared with 1 cast complication. Of 27 casted patients, 15 eventually had operative treatment after a mean delay of 1.7 years after casting. Cast treatment is a valuable delaying tactic for younger children with early-onset scoliosis. Spine deformity is adequately controlled, spine length is not compromised, and surgical complications associated with early GRI treatment are avoided. Copyright © 2013 Scoliosis Research Society. Published by Elsevier Inc. All rights reserved.

Accuracy of Digital vs Conventional Implant Impression Approach: A Three-Dimensional Comparative In Vitro Analysis.

PubMed

Basaki, Kinga; Alkumru, Hasan; De Souza, Grace; Finer, Yoav

To assess the three-dimensional (3D) accuracy and clinical acceptability of implant definitive casts fabricated using a digital impression approach and to compare the results with those of a conventional impression method in a partially edentulous condition. A mandibular reference model was fabricated with implants in the first premolar and molar positions to simulate a patient with bilateral posterior edentulism. Ten implant-level impressions per method were made using either an intraoral scanner with scanning abutments for the digital approach or an open-tray technique and polyvinylsiloxane material for the conventional approach. 3D analysis and comparison of implant location on resultant definitive casts were performed using laser scanner and quality control software. The inter-implant distances and interimplant angulations for each implant pair were measured for the reference model and for each definitive cast (n = 20 per group); these measurements were compared to calculate the magnitude of error in 3D for each definitive cast. The influence of implant angulation on definitive cast accuracy was evaluated for both digital and conventional approaches. Statistical analysis was performed using t test (α = .05) for implant position and angulation. Clinical qualitative assessment of accuracy was done via the assessment of the passivity of a master verification stent for each implant pair, and significance was analyzed using chi-square test (α = .05). A 3D error of implant positioning was observed for the two impression techniques vs the reference model, with mean ± standard deviation (SD) error of 116 ± 94 μm and 56 ± 29 μm for the digital and conventional approaches, respectively (P = .01). In contrast, the inter-implant angulation errors were not significantly different between the two techniques (P = .83). Implant angulation did not have a significant influence on definitive cast accuracy within either technique (P = .64). The verification stent demonstrated acceptable passive fit for 11 out of 20 casts and 18 out of 20 casts for the digital and conventional methods, respectively (P = .01). Definitive casts fabricated using the digital impression approach were less accurate than those fabricated from the conventional impression approach for this simulated clinical scenario. A significant number of definitive casts generated by the digital technique did not meet clinically acceptable accuracy for the fabrication of a multiple implant-supported restoration.

Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review.

PubMed

Miazek, Krystian; Kratky, Lukas; Sulc, Radek; Jirout, Tomas; Aguedo, Mario; Richel, Aurore; Goffin, Dorothee

2017-07-04

In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted.

Effect of Organic Solvents on Microalgae Growth, Metabolism and Industrial Bioproduct Extraction: A Review

PubMed Central

Miazek, Krystian; Sulc, Radek; Jirout, Tomas; Aguedo, Mario; Goffin, Dorothee

2017-01-01

In this review, the effect of organic solvents on microalgae cultures from molecular to industrial scale is presented. Traditional organic solvents and solvents of new generation-ionic liquids (ILs), are considered. Alterations in microalgal cell metabolism and synthesis of target products (pigments, proteins, lipids), as a result of exposure to organic solvents, are summarized. Applications of organic solvents as a carbon source for microalgal growth and production of target molecules are discussed. Possible implementation of various industrial effluents containing organic solvents into microalgal cultivation media, is evaluated. The effect of organic solvents on extraction of target compounds from microalgae is also considered. Techniques for lipid and carotenoid extraction from viable microalgal biomass (milking methods) and dead microalgal biomass (classical methods) are depicted. Moreover, the economic survey of lipid and carotenoid extraction from microalgae biomass, by means of different techniques and solvents, is conducted. PMID:28677659

Methods of producing adsorption media including a metal oxide

DOEpatents

Mann, Nicholas R; Tranter, Troy J

2014-03-04

Methods of producing a metal oxide are disclosed. The method comprises dissolving a metal salt in a reaction solvent to form a metal salt/reaction solvent solution. The metal salt is converted to a metal oxide and a caustic solution is added to the metal oxide/reaction solvent solution to adjust the pH of the metal oxide/reaction solvent solution to less than approximately 7.0. The metal oxide is precipitated and recovered. A method of producing adsorption media including the metal oxide is also disclosed, as is a precursor of an active component including particles of a metal oxide.

Solvent signal suppression for high-resolution MAS-DNP

NASA Astrophysics Data System (ADS)

Lee, Daniel; Chaudhari, Sachin R.; De Paëpe, Gaël

2017-05-01

Dynamic nuclear polarization (DNP) has become a powerful tool to substantially increase the sensitivity of high-field magic angle spinning (MAS) solid-state NMR experiments. The addition of dissolved hyperpolarizing agents usually results in the presence of solvent signals that can overlap and obscure those of interest from the analyte. Here, two methods are proposed to suppress DNP solvent signals: a Forced Echo Dephasing experiment (FEDex) and TRAnsfer of Populations in DOuble Resonance Echo Dephasing (TRAPDORED) NMR. These methods reintroduce a heteronuclear dipolar interaction that is specific to the solvent, thereby forcing a dephasing of recoupled solvent spins and leaving acquired NMR spectra free of associated resonance overlap with the analyte. The potency of these methods is demonstrated on sample types common to MAS-DNP experiments, namely a frozen solution (of L-proline) and a powdered solid (progesterone), both containing deuterated glycerol as a DNP solvent. The proposed methods are efficient, simple to implement, compatible with other NMR experiments, and extendable past spectral editing for just DNP solvents. The sensitivity gains from MAS-DNP in conjunction with FEDex or TRAPDORED then permits rapid and uninterrupted sample analysis.

An extensible framework for capturing solvent effects in computer generated kinetic models.

PubMed

Jalan, Amrit; West, Richard H; Green, William H

2013-03-14

Detailed kinetic models provide useful mechanistic insight into a chemical system. Manual construction of such models is laborious and error-prone, which has led to the development of automated methods for exploring chemical pathways. These methods rely on fast, high-throughput estimation of species thermochemistry and kinetic parameters. In this paper, we present a methodology for extending automatic mechanism generation to solution phase systems which requires estimation of solvent effects on reaction rates and equilibria. The linear solvation energy relationship (LSER) method of Abraham and co-workers is combined with Mintz correlations to estimate ΔG(solv)°(T) in over 30 solvents using solute descriptors estimated from group additivity. Simple corrections are found to be adequate for the treatment of radical sites, as suggested by comparison with known experimental data. The performance of scaled particle theory expressions for enthalpic-entropic decomposition of ΔG(solv)°(T) is also presented along with the associated computational issues. Similar high-throughput methods for solvent effects on free-radical kinetics are only available for a handful of reactions due to lack of reliable experimental data, and continuum dielectric calculations offer an alternative method for their estimation. For illustration, we model liquid phase oxidation of tetralin in different solvents computing the solvent dependence for ROO• + ROO• and ROO• + solvent reactions using polarizable continuum quantum chemistry methods. The resulting kinetic models show an increase in oxidation rate with solvent polarity, consistent with experiment. Further work needed to make this approach more generally useful is outlined.

Method for fabricating laminated uranium composites

DOEpatents

Chapman, L.R.

1983-08-03

The present invention is directed to a process for fabricating laminated composites of uranium or uranium alloys and at least one other metal or alloy. The laminated composites are fabricated by forming a casting of the molten uranium with the other metal or alloy which is selectively positioned in the casting and then hot-rolling the casting into a laminated plate in or around which the casting components are metallurgically bonded to one another to form the composite. The process of the present invention provides strong metallurgical bonds between the laminate components primarily since the bond disrupting surface oxides on the uranium or uranium alloy float to the surface of the casting to effectively remove the oxides from the bonding surfaces of the components.

Effects of Annular Electromagnetic Stirring Coupled with Intercooling on Grain Refinement and Homogeneity During Direct Chill Casting of Large-Sized 7005 Alloy Billet

NASA Astrophysics Data System (ADS)

Luo, Yajun; Zhang, Zhifeng; Li, Bao; Gao, Mingwei; Qiu, Yang; He, Min

2017-12-01

To obtain a large-sized, high-quality aluminum alloy billet, an advanced uniform direct chill (UDC) casting method was developed by combining annular electromagnetic stirring (A-EMS) with intercooling in the sump. The 7005 alloy was chosen to investigate the effect of UDC on grain refinement and homogeneity during normal direct chill (NDC) casting. It was concluded that the microstructure consisting of both primary α-Al phase and secondary phases becomes finer and more homogeneous for the billets prepared with UDC casting compared to those prepared with NDC casting, and the forced cooling from both the inner and outer melt under A-EMS has a measurable effect on grain refinement and homogeneity.

Modelling the Cast Component Weight in Hot Chamber Die Casting using Combined Taguchi and Buckingham's π Approach

NASA Astrophysics Data System (ADS)

Singh, Rupinder

2018-02-01

Hot chamber (HC) die casting process is one of the most widely used commercial processes for the casting of low temperature metals and alloys. This process gives near-net shape product with high dimensional accuracy. However in actual field environment the best settings of input parameters is often conflicting as the shape and size of the casting changes and one have to trade off among various output parameters like hardness, dimensional accuracy, casting defects, microstructure etc. So for online inspection of the cast components properties (without affecting the production line) the weight measurement has been established as one of the cost effective method (as the difference in weight of sound and unsound casting reflects the possible casting defects) in field environment. In the present work at first stage the effect of three input process parameters (namely: pressure at 2nd phase in HC die casting; metal pouring temperature and die opening time) has been studied for optimizing the cast component weight `W' as output parameter in form of macro model based upon Taguchi L9 OA. After this Buckingham's π approach has been applied on Taguchi based macro model for the development of micro model. This study highlights the Taguchi-Buckingham based combined approach as a case study (for conversion of macro model into micro model) by identification of optimum levels of input parameters (based on Taguchi approach) and development of mathematical model (based on Buckingham's π approach). Finally developed mathematical model can be used for predicting W in HC die casting process with more flexibility. The results of study highlights second degree polynomial equation for predicting cast component weight in HC die casting and suggest that pressure at 2nd stage is one of the most contributing factors for controlling the casting defect/weight of casting.

Screening Chemicals for Estrogen Receptor Bioactivity Using a Computational Model.

PubMed

Browne, Patience; Judson, Richard S; Casey, Warren M; Kleinstreuer, Nicole C; Thomas, Russell S

2015-07-21

The U.S. Environmental Protection Agency (EPA) is considering high-throughput and computational methods to evaluate the endocrine bioactivity of environmental chemicals. Here we describe a multistep, performance-based validation of new methods and demonstrate that these new tools are sufficiently robust to be used in the Endocrine Disruptor Screening Program (EDSP). Results from 18 estrogen receptor (ER) ToxCast high-throughput screening assays were integrated into a computational model that can discriminate bioactivity from assay-specific interference and cytotoxicity. Model scores range from 0 (no activity) to 1 (bioactivity of 17β-estradiol). ToxCast ER model performance was evaluated for reference chemicals, as well as results of EDSP Tier 1 screening assays in current practice. The ToxCast ER model accuracy was 86% to 93% when compared to reference chemicals and predicted results of EDSP Tier 1 guideline and other uterotrophic studies with 84% to 100% accuracy. The performance of high-throughput assays and ToxCast ER model predictions demonstrates that these methods correctly identify active and inactive reference chemicals, provide a measure of relative ER bioactivity, and rapidly identify chemicals with potential endocrine bioactivities for additional screening and testing. EPA is accepting ToxCast ER model data for 1812 chemicals as alternatives for EDSP Tier 1 ER binding, ER transactivation, and uterotrophic assays.

Molding of strength testing samples using modern PDCPD material for purpose of automotive industry

NASA Astrophysics Data System (ADS)

Grabowski, L.; Baier, A.; Sobek, M.

2017-08-01

The casting of metal materials is widely known but the molding of composite polymer materials is not well-known method still. The initial choice of method for producing composite bodies was the method of casting of PDCPD material. For purpose of performing casting of polymer composite material, a special mold was made. Firstly, the 3D printed, using PLA material, mold was used. After several attempts of casting PDCPD many problems were encountered. The second step was to use mold milled from a firm and dense isocyanate foam. After several attempts research shown that this solution is more resistant to high-temperature peak, but this material is too fragile to use it several times. This solution also prevents mold from using external heating, which can be necessary for performing correct molding process. The last process was to use the aluminum mold, which is dedicated to PDCPD polymer composite, because of low adhesiveness. This solution leads to perform correct PDCPD polymer composite material injection. After performing casting operation every PDCPD testing samples were tested. These results were compared together. The result of performed work was to archive correct properties of injection of composite material. Research and results were described in detail in this paper.

Method of analysis of polymerizable monomeric species in a complex mixture

DOEpatents

Hermes, Robert E

2014-03-18

Method of selective quantitation of a polymerizable monomeric species in a well spacer fluid, said method comprising the steps of adding at least one solvent having a refractive index of less than about 1.33 to a sample of the complex mixture to produce a solvent phase, and measuring the refractive index of the solvent phase.

Feasibility of producing cast-refractory metal-fiber superalloy composites

NASA Technical Reports Server (NTRS)

Mcintyre, R. D.

1973-01-01

A study was conducted to evaluate the feasibility of direct casting as a practical method for producing cast superalloy tungsten or columbium alloy fiber composites while retaining a high percentage of fiber strength. Fourteen nickel base, four cobalt, and three iron based matrices were surveyed for their degree of reaction with the metal fibers. Some stress-rupture results were obtained at temperatures of 760, 816, 871, and 1093 C for a few composite systems. The feasibility of producing acceptable composites of some cast nickel, cobalt, and iron matrix alloys with tungsten or columbium alloy fibers was demonstrated.

Methods for Casting Subterranean Ant Nests

PubMed Central

Tschinkel, Walter R.

2010-01-01

The study of subterranean ant nests has been impeded by the difficulty of rendering their structures in visible form. Here, several different casting materials are shown to make perfect casts of the underground nests of ants. Each material (dental plaster, paraffin wax, aluminum, zinc) has advantages and limitations, which are discussed. Some of the materials allow the recovery of the ants entombed in the casts, allowing a census of the ants to be connected with features of their nest architecture. The necessary equipment and procedures are described in the hope that more researchers will study this very important aspect of ant natural history. PMID:20673073

Fabrication of cylindrical superhydrophobic microchannels by replicating lotus leaf structures on internal walls

NASA Astrophysics Data System (ADS)

Das, Ajit; Bhaumik, Soubhik Kumar

2018-04-01

Cylindrical superhydrophobic microchannels are fabricated by replicating lotus leaf structures on internal walls. The fabrication process comprises of three steps: the creation of a cylindrical mold of a glass rod (125 µm) with polystyrene films bearing negative imprints of lotus leaf (superhydrophobic) structures; casting polydimethylsiloxane (PDMS, Sylgard 184) over the mold; and solvent-assisted pulling off of the glass rod to leave a positive replica on the inner wall of the PDMS cast. The last crucial step is achieved through selective dissolution of the intermediate negative replica layer in the cylindrical mold without any swelling effect. The high fidelity of the replication process is confirmed through scanning electron microscope (SEM) imaging. The attained superhydrophobicity is assessed by comparing the dynamics of the advancing meniscus in the fabricated microchannels with that over a similarly fabricated smooth microchannel. Contact angle studies of the meniscus reveal a lower capillary effect and drag force experienced by the superhydrophobic microchannel compared to smooth ones. Studies based on velocity lead to a prediction of a drag reduction of 35%. A new avenue is thus opened up for microfabrication and flow analysis of closed superhydrophobic (SH) conduits in lab on chip and microfluidic applications.

Development of Craze and Impact Resistance in Glazing Plastics by Multiaxial Stretching

NASA Technical Reports Server (NTRS)

Kline, G M; Wolock, I; Axilrod, B M; Sherman, M A; George, D A; Cohen, V

1956-01-01

The loss of strength of cast polymethyl methacrylate plastic as a result of crazing is of considerable importance to the aircraft industry. Because of the critical need for basic information on the nature of crazing and the effects of various treatments and environmental conditions on its incidence and magnitude, an investigation of this phenomenon was undertaken. The following factors were examined: (1) the effect of stress-solvent crazing on tensile strength of polymethyl methacrylate; (2) the critical stress and strain for onset of crazing at various temperatures; (3) the effect of molecular weight on crazing; and (4) the effect of multiaxial stretching on crazing of polymethyl methacrylate and other acrylic glazing materials.

Diorganosilacetylene-alt-diorganosilvinylene polymers and a process densifying porous silicon-carbide bodies

DOEpatents

Barton, Thomas J.; Ijadi-Maghsoodi, Sina; Pang, Yi

1994-05-17

The present invention provides linear organosilicon polymers including acetylene and vinylene moieties, and a process for their preparation. These diorganosilacetylene-alt-diorganosilvinylene linear polymers can be represented by the formula: --[--(R.sup.1)(R.sup.2)Si--C.tbd.C--(R.sup.3)(R.sup.4)Si--CH=CH--].sub.n-- , wherein n.gtoreq.2; and each R.sup.1, R.sup.2, R.sup.3, and R.sup.4 is independently selected from the group consisting of hydrogen, halogen, alkyl, alkenyl, aryl, and aralkyl radicals. The polymers are soluble in organic solvents, air stable, and can be pulled into fibers or cast into films. They can be thermally converted into silicon carbide ceramic materials.