Structural alloy with a protective coating containing silicon or silicon-oxide

DOEpatents

Natesan, K.

1994-12-27

An iron-based alloy is described containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100 C. 8 figures.

Structural alloy with a protective coating containing silicon or silicon-oxide

DOEpatents

Natesan, Ken

1994-01-01

An iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100.degree. C.

The Failure of Absorption of DC Silicone Fluid 703 from the Gastrointestinal Tract of Rats

PubMed Central

Paul, J.; Pover, W. F. R.

1960-01-01

The intestinal absorption of silicone fluid 703, a methyl phenyl polysiloxane, has been studied in the rat. This silicone was chosen for the present investigation because of its lipid-like character and its solubility in olive oil. The experimental findings demonstrate that very little, if any, silicone is absorbed when fed in olive oil. No silicone was found in the lymph lipids of cannulated rats fed the silicone, and balance experiments by recovery of the organosilicon compound and triglyceride after feeding to rats for three hours showed that 85% of silicone fluid 703 was recovered from the gastrointestinal tract, whereas 70% of the fed triglyceride was absorbed. The unabsorbed silicone was concentrated chiefly in the intestinal lumen. Balance experiments by recovery of the organosilicon compound after long-term feeding gave recoveries of 96% of the silicone. This amount was recovered entirely from the lower part of the gastrointestinal tract and the faeces. No silicon fluid 703 was found in the liver, kidneys, or fat depots. The urine contained no soluble silica. PMID:14430986

The Electrochemical Fluorination of Organosilicon Compounds

NASA Technical Reports Server (NTRS)

Seaver, Robert E.

1961-01-01

The electrochemical fluorination of tetramethylsilane, hexamethyl-disiloxane, diethyldichlorosilane, amyltrichlorosilane, and phenyltri-chlorosilane was conducted in an Inconel cell equipped with nickel electrodes. A potential of approximately 5.0 volts and a current of approximately 1.0 ampere were used for the electrolysis reaction. In all cases the fluorinations resulted in considerable scission of the carbon-silicon bonds yielding hydrogen and the various fluorinated decomposition products; no fluoroorganosilicon compounds were identified. The main decomposition products were silicon tetrafluoride, the corresponding fluorinated carbon compounds, and the various organofluorosilanes. It is suggested that this is due to the nucleophilic attack of the fluoride ion (or complex fluoride ion) on the carbon-silicon bond.

Silicon carbide sintered body manufactured from silicon carbide powder containing boron, silicon and carbonaceous additive

NASA Technical Reports Server (NTRS)

Tanaka, Hidehiko

1987-01-01

A silicon carbide powder of a 5-micron grain size is mixed with 0.15 to 0.60 wt% mixture of a boron compound, i.e., boric acid, boron carbide (B4C), silicon boride (SiB4 or SiB6), aluminum boride, etc., and an aluminum compound, i.e., aluminum, aluminum oxide, aluminum hydroxide, aluminum carbide, etc., or aluminum boride (AlB2) alone, in such a proportion that the boron/aluminum atomic ratio in the sintered body becomes 0.05 to 0.25 wt% and 0.05 to 0.40 wt%, respectively, together with a carbonaceous additive to supply enough carbon to convert oxygen accompanying raw materials and additives into carbon monoxide.

Structural alloy with a protective coating containing silicon or silicon-oxide

DOEpatents

Natesan, K.

1992-01-01

This invention is comprised of an iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100{degrees}C.

Process for removal of water and silicon mu-oxides from chlorosilanes

DOEpatents

Tom, Glenn M.; McManus, James V.

1992-03-10

A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising: (a) a support; and (b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula: R.sub.a-x MCl.sub.x wherein: M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum; R is alkyl; a is a number equal to the valency of metal M; and x is a number having a value of from 0 to a, inclusive; and wherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of: (i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y, wherein y is a number having a value of from 1 to 3, inclusive; and (ii) reaction of such compound(s) with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y wherein y is a number having a value of 1 to 3, inclusive. A corresponding method of making the scavenger composition, and of purifying a chlorosilane which contains oxygen and silicon mu-oxide impurities, likewise are disclosed, together with a purifier apparatus, in which a bed of the scavenger composition is disposed. The composition, purification process, and purifier apparatus of the invention have utility in purifying gaseous chlorosilanes which are employed in the semiconductor industry as silicon source reagents for forming epitaxial silicon layers.

Composition, process, and apparatus, for removal of water and silicon mu-oxides from chlorosilanes

DOEpatents

Tom, Glenn M.; McManus, James V.

1991-10-15

A scavenger composition having utility for removal of water and silicon mu-oxide impurities from chlorosilanes, such scavenger composition comprising: (a) a support; and (b) associated with the support, one or more compound(s) selected from the group consisting of compounds of the formula: R.sub.a-x MCl.sub.x wherein: M is a metal selected from the group consisting of the monovalent metals lithium, sodium, and potassium; the divalent metals magnesium, strontium, barium, and calcium; and the trivalent metal aluminum; R is alkyl; a is a number equal to the valency of metal M; and x is a number having a value from 0 to a, inclusive; and wherein said compound(s) of the formula R.sub.a-x MCl.sub.x have been activated for impurity-removal service by a reaction scheme selected from those of the group consisting of: (i) reaction of such compound(s) with hydrogen chloride to form a first reaction product therefrom, followed by reaction of the first reaction product with a chlorosilane of the formula: SiH.sub.4"y Cl.sub.y, wherein y is a number having a value of from 1 to 3, inclusive; and (ii) reaction of such compound(s) with a chlorosilane of the formula: SiH.sub.4-y Cl.sub.y wherein y is a number having a value of 1 to 3, inclusive. A corresponding method of making the scavenger composition, and of purifying a chlorosilane which contains oxygen and silicon mu-oxide impurities, likewise are disclosed, together with a purifier apparatus, in which a bed of the scavenger composition is disposed. The composition, purification process, and purifier apparatus of the invention have utility in purifying gaseous chlorosilanes which are employed in the semiconductor industry as silicon source reagents for forming epitaxial silicon layers.

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

Novel Drift Structures for Silicon and Compound Semiconductor X-Ray and Gamma-Ray Detectors

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

Bradley E. Patt; Jan S. Iwanczyk

Recently developed silicon- and compound-semiconductor-based drift detector structures have produced excellent performance for charged particles, X rays, and gamma rays and for low-signal visible light detection. The silicon drift detector (SDD) structures that we discuss relate to direct X-ray detectors and scintillation photon detectors coupled with scintillators for gamma rays. Recent designs include several novel features that ensure very low dark current (both bulk silicon dark current and surface dark current) and hence low noise. In addition, application of thin window technology ensures a very high quantum efficiency entrance window on the drift photodetector.

Reactivity of the Donor-Stabilized Silylenes [iPrNC(Ph)NiPr]2 Si and [iPrNC(NiPr2 )NiPr]2 Si: Activation of CO2 and CS2.

PubMed

Mück, Felix M; Baus, Johannes A; Nutz, Marco; Burschka, Christian; Poater, Jordi; Bickelhaupt, F Matthias; Tacke, Reinhold

2015-11-09

Activation of CO2 by the bis(amidinato)silylene 1 and the analogous bis(guanidinato)silylene 2 leads to the structurally analogous six-coordinate silicon(IV) complexes 4 (previous work) and 8, respectively, the first silicon compounds with a chelating carbonato ligand. Likewise, CS2 activation by silylene 1 affords the analogous six-coordinate silicon(IV) complex 10, the first silicon compound with a chelating trithiocarbonato ligand. CS2 activation by silylene 2, however, yields the five-coordinate silicon(IV) complex 13 with a carbon-bound CS2 (2-) ligand, which also represents an unprecedented coordination mode in silicon coordination chemistry. Treatment of the dinuclear silicon(IV) complexes 5 and 6 with CO2 also affords the six-coordinate carbonatosilicon(IV) complexes 4 and 8, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multi-stir bar sorptive extraction for analysis of odor compounds in aqueous samples.

PubMed

Ochiai, Nobuo; Sasamoto, Kikuo; Ieda, Teruyo; David, Frank; Sandra, Pat

2013-11-08

As reproducible coating of stir bars with more polar phases was found to be very difficult, a supporting grid was used in the development of an ethyleneglycol-modified Silicone (EG Silicone) coated stir bar. This new polar coating showed good performance for the extraction of polar solutes, but long term use also showed degradation of the coating due to friction while stirring. In order to address the lower robustness of the EG Silicone stir bar which has a much softer coating compared to a conventional polydimethylsiloxane (PDMS) stir bar, a novel SBSE procedure termed multi-SBSE ((m)SBSE) was developed. (m)SBSE consists of the robust PDMS stir bar stirring at the bottom of the vial and the EG Silicone stir bar attached on the inner side wall of the vial (a magnetic clip is used for the set-up). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously thermally desorbed. The desorbed compounds were analyzed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Compared to conventional SBSE, (m)SBSE provides more uniform enrichment of a wide range of odor compounds in aqueous sample since both stir bars can complement each other, while eliminating the damage of the EG Silicone phase during the extraction. The robustness of the EG Silicone stir bar was dramatically increased and more than 30 extraction and desorption cycles were possible without loss in performance. The recoveries for polar solutes such as 2-acetyl pyrrole (logKow: 0.55), benzyl alcohol (logKow: 1.08), guaiacol (logKow: 1.34), and indole (logKow: 2.05) were increased by a factor of about 2-7. The (m)SBSE-TD-GC-MS method showed good linearity (r(2)>0.9913) and high sensitivity (limit of detection: 0.011-0.071 ng mL(-1)) for the test compounds spiked in water. The feasibility and benefit of the method was demonstrated with analysis of odor compounds in roasted green tea. The normalized areas obtained from (m)SBSE showed the best enrichment for most of the selected compounds compared to conventional SBSE using the PDMS stir bar or the EG Silicone stir bar. Fifteen compounds were determined in the range of 0.15-210 ng mL(-1) (RSD<14%, n=6). Copyright © 2013 Elsevier B.V. All rights reserved.

Organosilicon compounds. XVIII - Silicon-containing dianhydrides

NASA Technical Reports Server (NTRS)

Pratt, J. R.; Thames, S. F.

1973-01-01

Description of four new silicon-containing dianhydrides synthetized in an attempt to provide useful silicon-containing polyimide precursors. They were prepared by aqueous potassium permanganate-pyridine oxidations of corresponding tetramethyl intermediates to form tetracarboxylic acids, which were dehydrated to the dianhydrides.

[Characteristics of organic pollutants in the sediments from a typical electronics industrial zone].

PubMed

Liu, Jin; Deng, Dai-Yong; Xu, Mei-Ying; Sun, Guo-Ping

2013-03-01

In order to investigate the contamination status of organic pollutants in a river of a typical electrical equipment industrial area, Ronggui, Foshan, the sediments were sampled for the composition, concentration and occurrence analysis of organic pollutants. The polar and non-polar fractionation methods were employed for the fingerprint establishment of organic pollutants. One hundred and seventy-one of organic chemicals including ten categories of alkanes, alkenes, polycyclic aromatic hydrocarbons, benzene, heterocyclic compounds, phthalate esters, aldehydes, ketones, polar compounds, silicon-containing material as well as alkyl esters were examined. The number of different categories of the detected organic pollutants in a descending order was: alkanes > polar compounds > polycyclic aromatic hydrocarbons > aldehydes and ketones > heterocyclic compounds > benzene homologues, phthalate ester > alkyl esters > silicon material > olefins. The abundance of detected organic pollutants in a descending order was: alkanes > polar compounds > alkyl esters > olefins > polycyclic aromatic hydrocarbons > phthalates > silicon material > aldehydes and ketones > heterocyclic compounds > benzene homologues. Among the 51 kinds of alkanes detected, nonadecane accounted for 14.83%, and the persistent organic pollutants accounted for 2.33% of the total organic matter. Compared to similar studies, there were 51 kinds of alkanes and they accounted for 55.5% of the total organic chemicals, showing high diversity and abundance. In addition, some electronics industry-related organic pollutants such as silicone materials were also detected in high frequency.

Use of silicon in liquid sintered silicon nitrides and sialons

DOEpatents

Raj, Rishi; Baik, Sunggi

1984-12-11

This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

Biological and therapeutic effects of ortho-silicic acid and some ortho-silicic acid-releasing compounds: New perspectives for therapy.

PubMed

Jurkić, Lela Munjas; Cepanec, Ivica; Pavelić, Sandra Kraljević; Pavelić, Krešimir

2013-01-08

Silicon (Si) is the most abundant element present in the Earth's crust besides oxygen. However, the exact biological roles of silicon remain unknown. Moreover, the ortho-silicic acid (H4SiO4), as a major form of bioavailable silicon for both humans and animals, has not been given adequate attention so far. Silicon has already been associated with bone mineralization, collagen synthesis, skin, hair and nails health atherosclerosis, Alzheimer disease, immune system enhancement, and with some other disorders or pharmacological effects. Beside the ortho-silicic acid and its stabilized formulations such as choline chloride-stabilized ortho-silicic acid and sodium or potassium silicates (e.g. M2SiO3; M= Na,K), the most important sources that release ortho-silicic acid as a bioavailable form of silicon are: colloidal silicic acid (hydrated silica gel), silica gel (amorphous silicon dioxide), and zeolites. Although all these compounds are characterized by substantial water insolubility, they release small, but significant, equilibrium concentration of ortho-silicic acid (H4SiO4) in contact with water and physiological fluids. Even though certain pharmacological effects of these compounds might be attributed to specific structural characteristics that result in profound adsorption and absorption properties, they all exhibit similar pharmacological profiles readily comparable to ortho-silicic acid effects. The most unusual ortho-silicic acid-releasing agents are certain types of zeolites, a class of aluminosilicates with well described ion(cation)-exchange properties. Numerous biological activities of some types of zeolites documented so far might probably be attributable to the ortho-silicic acid-releasing property. In this review, we therefore discuss biological and potential therapeutic effects of ortho-silicic acid and ortho-silicic acid -releasing silicon compounds as its major natural sources.

Process for depositing an oxide epitaxially onto a silicon substrate and structures prepared with the process

DOEpatents

McKee, Rodney A.; Walker, Frederick J.

1993-01-01

A process and structure involving a silicon substrate utilizes an ultra high vacuum and molecular beam epitaxy (MBE) methods to grow an epitaxial oxide film upon a surface of the substrate. As the film is grown, the lattice of the compound formed at the silicon interface becomes stabilized, and a base layer comprised of an oxide having a sodium chloride-type lattice structure grows epitaxially upon the compound so as to cover the substrate surface. A perovskite may then be grown epitaxially upon the base layer to render a product which incorporates silicon, with its electronic capabilities, with a perovskite having technologically-significant properties of its own.

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds

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

Horie, Hiro-omi; Kikudome, Takashi; Teramura, Kyosuke

Formation conditions of two types of sodium containing silicon clathrate compounds were determined by the controlled thermal decomposition of sodium monosilicide NaSi under vacuum. The decomposition began at 360 deg. C. Much higher decomposition temperatures and the presence of sodium metal vapor were favorable for the formation of type I clathrate compound Na{sub 8}Si{sub 46}. Type II clathrate compound Na{sub x}Si{sub 136} was obtained as a single phase at a decomposition temperature <440 deg. C under the condition without sodium metal vapor. The type I clathrate compound was decomposed to crystalline Si above 520 deg. C. The type II clathratemore » compound was thermally more stable, and retained at least up to 550 deg. C in vacuum. - Graphical Abstract: The optimal condition to prepare type II silicon clathrate Na{sub x}Si{sub 136} with minimal contamination of the type I phase is proposed. The starting NaSi should be thermally decomposed below 440 deg. C, and the rapid removal of Na vapor evolved is essentially important.« less

A study of the dynamic flammability of radiation cross-linked flame-retardant HDPE/EPDM/silicon-elastomer compound

NASA Astrophysics Data System (ADS)

Jia, Shaojin; Zhang, Zhicheng; Du, Zhiwen; Teng, Renrui; Wang, Zhengzhou

2003-04-01

A dynamic flammability study of flame-retardant compound consisting of HDPE, EPDM and silicon elastomer blended with additives, as wire and cable insulation was made before and after irradiation. The data of RHR, EHC, SEC and the concentration of CO and CO 2 from cone colorimeter shown in the burning process were accessed. By blending silicon elastomer, CO release rate was reduced and the thermal endurance was improved. Oxygen index, mechanical property, morphology of the char formed in dynamical flame and thermal stability were also investigated.

Laser-induced phase separation of silicon carbide

PubMed Central

Choi, Insung; Jeong, Hu Young; Shin, Hyeyoung; Kang, Gyeongwon; Byun, Myunghwan; Kim, Hyungjun; Chitu, Adrian M.; Im, James S.; Ruoff, Rodney S.; Choi, Sung-Yool; Lee, Keon Jae

2016-01-01

Understanding the phase separation mechanism of solid-state binary compounds induced by laser–material interaction is a challenge because of the complexity of the compound materials and short processing times. Here we present xenon chloride excimer laser-induced melt-mediated phase separation and surface reconstruction of single-crystal silicon carbide and study this process by high-resolution transmission electron microscopy and a time-resolved reflectance method. A single-pulse laser irradiation triggers melting of the silicon carbide surface, resulting in a phase separation into a disordered carbon layer with partially graphitic domains (∼2.5 nm) and polycrystalline silicon (∼5 nm). Additional pulse irradiations cause sublimation of only the separated silicon element and subsequent transformation of the disordered carbon layer into multilayer graphene. The results demonstrate viability of synthesizing ultra-thin nanomaterials by the decomposition of a binary system. PMID:27901015

Functional Group Analysis.

ERIC Educational Resources Information Center

Smith, Walter T., Jr.; Patterson, John M.

1984-01-01

Literature on analytical methods related to the functional groups of 17 chemical compounds is reviewed. These compounds include acids, acid azides, alcohols, aldehydes, ketones, amino acids, aromatic hydrocarbons, carbodiimides, carbohydrates, ethers, nitro compounds, nitrosamines, organometallic compounds, peroxides, phenols, silicon compounds,…

Use of silicon in liquid sintered silicon nitrides and sialons

DOEpatents

Raj, R.; Baik, S.

1984-12-11

This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

Use of free silicon in liquid phase sintering of silicon nitrides and sialons

DOEpatents

Raj, R.; Baik, S.

1985-11-12

This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic. 4 figs.

Use of free silicon in liquid phase sintering of silicon nitrides and sialons

DOEpatents

Raj, Rishi; Baik, Sunggi

1985-11-12

This invention relates to the production of improved high density nitrogen based ceramics by liquid-phase densification of silicon nitride or a compound of silicon-nitrogen-oxygen-metal, e.g. a sialon. In the process and compositions of the invention minor amounts of finely divided silicon are employed together with the conventional liquid phase producing additives to enhance the densification of the resultant ceramic.

Compounding with Silicones.

PubMed

Allen, Loyd V

2015-01-01

Since the 1940s, methylchlorosilanes have been used to treat glassware to prevent blood from clotting. The use of silicones in pharmaceutical and medical applications has grown to where today they are used in many life-saving devices (pacemakers, hydrocephalic shunts) and pharmaceutical applications from tubing, to excipients in topical formulations, to adhesives to affix transdermal drug delivery systems, and are also being used in products as active pharmaceutical ingredients, such as antiflatulents. About 60% of today's skin-care products now contain some type of silicone where they are considered safe and are known to provide a pleasant "silky-touch," non-greasy, and non-staining feel. Silicones exhibit many useful characteristics, and the safety of these agents supports their numerous applications; their biocompatibility is partially due to their low-chemical reactivity displayed by silicones, low-surface energy, and their hydrophobicity. Silicones are used both as active ingredients and as excipients. In addition is their use for "siliconization," or surface treatment, of many parenteral packaging components. Dimethicone and silicone oil are used as lubricants on stoppers to aid machineability, in syringes to aid piston movement, or on syringe needles to reduce pain upon injection. Silicones are also useful in pharmaceutical compounding as is discussed in this artiele included with this article are in developing formulations with silicones.

Controlled thermal decomposition of NaSi to derive silicon clathrate compounds

NASA Astrophysics Data System (ADS)

Horie, Hiro-omi; Kikudome, Takashi; Teramura, Kyosuke; Yamanaka, Shoji

2009-01-01

Formation conditions of two types of sodium containing silicon clathrate compounds were determined by the controlled thermal decomposition of sodium monosilicide NaSi under vacuum. The decomposition began at 360 °C. Much higher decomposition temperatures and the presence of sodium metal vapor were favorable for the formation of type I clathrate compound Na 8Si 46. Type II clathrate compound Na xSi 136 was obtained as a single phase at a decomposition temperature <440 °C under the condition without sodium metal vapor. The type I clathrate compound was decomposed to crystalline Si above 520 °C. The type II clathrate compound was thermally more stable, and retained at least up to 550 °C in vacuum.

Silicone wristbands as personal passive samplers.

PubMed

O'Connell, Steven G; Kincl, Laurel D; Anderson, Kim A

2014-03-18

Active-sampling approaches are commonly used for personal monitoring, but are limited by energy usage and data that may not represent an individual's exposure or bioavailable concentrations. Current passive techniques often involve extensive preparation, or are developed for only a small number of targeted compounds. In this work, we present a novel application for measuring bioavailable exposure with silicone wristbands as personal passive samplers. Laboratory methodology affecting precleaning, infusion, and extraction were developed from commercially available silicone, and chromatographic background interference was reduced after solvent cleanup with good extraction efficiency (>96%). After finalizing laboratory methods, 49 compounds were sequestered during an ambient deployment which encompassed a diverse set of compounds including polycyclic aromatic hydrocarbons (PAHs), consumer products, personal care products, pesticides, phthalates, and other industrial compounds ranging in log K(ow) from -0.07 (caffeine) to 9.49 (tris(2-ethylhexyl) phosphate). In two hot asphalt occupational settings, silicone personal samplers sequestered 25 PAHs during 8- and 40-h exposures, as well as 2 oxygenated-PAHs (benzofluorenone and fluorenone) suggesting temporal sensitivity over a single work day or week (p < 0.05, power =0.85). Additionally, the amount of PAH sequestered differed between worksites (p < 0.05, power = 0.99), suggesting spatial sensitivity using this novel application.

Quantitation of buried contamination by use of solvents. [degradation of silicone polymers by amine solvents

NASA Technical Reports Server (NTRS)

Pappas, S. P.; Hsiao, Y. C.; Hill, L. W.

1973-01-01

Spore recovery form cured silicone potting compounds using amine solvents to degrade the cured polymers was investigated. A complete list of solvents and a description of the effect of each on two different silicone polymers is provided.

Photoluminescent silicon nanocrystals with chlorosilane surfaces - synthesis and reactivity

NASA Astrophysics Data System (ADS)

Höhlein, Ignaz M. D.; Kehrle, Julian; Purkait, Tapas K.; Veinot, Jonathan G. C.; Rieger, Bernhard

2014-12-01

We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place.We present a new efficient two-step method to covalently functionalize hydride terminated silicon nanocrystals with nucleophiles. First a reactive chlorosilane layer was formed via diazonium salt initiated hydrosilylation of chlorodimethyl(vinyl)silane which was then reacted with alcohols, silanols and organolithium reagents. With organolithium compounds a side reaction is observed in which a direct functionalization of the silicon surface takes place. Electronic supplementary information (ESI) available: Detailed experimental procedures and additional NMR, PL, EDX, DLS and TEM data. See DOI: 10.1039/C4NR05888G

In-situ formation of nanoparticles within a silicon-based matrix

DOEpatents

Thoma, Steven G [Albuquerque, NM; Wilcoxon, Jess P [Albuquerque, NM; Abrams, Billie L [Albuquerque, NM

2008-06-10

A method for encapsulating nanoparticles with an encapsulating matrix that minimizes aggregation and maintains favorable properties of the nanoparticles. The matrix comprises silicon-based network-forming compounds such as ormosils and polysiloxanes. The nanoparticles are synthesized from precursors directly within the silicon-based matrix.

Quantitative structure-activity relationship for the partition coefficient of hydrophobic compounds between silicone oil and air.

PubMed

Qu, Yanfei; Ma, Yongwen; Wan, Jinquan; Wang, Yan

2018-06-01

The silicon oil-air partition coefficients (K SiO/A ) of hydrophobic compounds are vital parameters for applying silicone oil as non-aqueous-phase liquid in partitioning bioreactors. Due to the limited number of K SiO/A values determined by experiment for hydrophobic compounds, there is an urgent need to model the K SiO/A values for unknown chemicals. In the present study, we developed a universal quantitative structure-activity relationship (QSAR) model using a sequential approach with macro-constitutional and micromolecular descriptors for silicone oil-air partition coefficients (K SiO/A ) of hydrophobic compounds with large structural variance. The geometry optimization and vibrational frequencies of each chemical were calculated using the hybrid density functional theory at the B3LYP/6-311G** level. Several quantum chemical parameters that reflect various intermolecular interactions as well as hydrophobicity were selected to develop QSAR model. The result indicates that a regression model derived from logK SiO/A , the number of non-hydrogen atoms (#nonHatoms) and energy gap of E LUMO and E HOMO (E LUMO -E HOMO ) could explain the partitioning mechanism of hydrophobic compounds between silicone oil and air. The correlation coefficient R 2 of the model is 0.922, and the internal and external validation coefficient, Q 2 LOO and Q 2 ext , are 0.91 and 0.89 respectively, implying that the model has satisfactory goodness-of-fit, robustness, and predictive ability and thus provides a robust predictive tool to estimate the logK SiO/A values for chemicals in application domain. The applicability domain of the model was visualized by the Williams plot.

Silicone Wristbands as Personal Passive Samplers

PubMed Central

2014-01-01

Active-sampling approaches are commonly used for personal monitoring, but are limited by energy usage and data that may not represent an individual’s exposure or bioavailable concentrations. Current passive techniques often involve extensive preparation, or are developed for only a small number of targeted compounds. In this work, we present a novel application for measuring bioavailable exposure with silicone wristbands as personal passive samplers. Laboratory methodology affecting precleaning, infusion, and extraction were developed from commercially available silicone, and chromatographic background interference was reduced after solvent cleanup with good extraction efficiency (>96%). After finalizing laboratory methods, 49 compounds were sequestered during an ambient deployment which encompassed a diverse set of compounds including polycyclic aromatic hydrocarbons (PAHs), consumer products, personal care products, pesticides, phthalates, and other industrial compounds ranging in log Kow from −0.07 (caffeine) to 9.49 (tris(2-ethylhexyl) phosphate). In two hot asphalt occupational settings, silicone personal samplers sequestered 25 PAHs during 8- and 40-h exposures, as well as 2 oxygenated-PAHs (benzofluorenone and fluorenone) suggesting temporal sensitivity over a single work day or week (p < 0.05, power =0.85). Additionally, the amount of PAH sequestered differed between worksites (p < 0.05, power = 0.99), suggesting spatial sensitivity using this novel application. PMID:24548134

Microminiature gas chromatograph

DOEpatents

Yu, Conrad M.

1996-01-01

A microminiature gas chromatograph (.mu.GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode.

Interior phase transformations and mass-radius relationships of silicon-carbon planets

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

Wilson, Hugh F.; Militzer, Burkhard, E-mail: hughfw@gmail.com

2014-09-20

Planets such as 55 Cancri e orbiting stars with a high carbon-to-oxygen ratio may consist primarily of silicon and carbon, with successive layers of carbon, silicon carbide, and iron. The behavior of silicon-carbon materials at the extreme pressures prevalent in planetary interiors, however, has not yet been sufficiently understood. In this work, we use simulations based on density functional theory to determine high-pressure phase transitions in the silicon-carbon system, including the prediction of new stable compounds with Si{sub 2}C and SiC{sub 2} stoichiometry at high pressures. We compute equations of state for these silicon-carbon compounds as a function of pressure,more » and hence derive interior structural models and mass-radius relationships for planets composed of silicon and carbon. Notably, we predict a substantially smaller radius for SiC planets than in previous models, and find that mass radius relationships for SiC planets are indistinguishable from those of silicate planets. We also compute a new equation of state for iron. We rederive interior models for 55 Cancri e and are able to place more stringent restrictions on its composition.« less

FUEL ELEMENTS AND METHOD OF MAKING

DOEpatents

Noland, R.A.; Marzano, C.

1958-08-19

A process is described of surface-impregnating bodies of metallic uranium with silicon. Silicon metal is added to or admixed with alkali metal selected from the group consisting of sodiunn, potassium, and sodiunnpotassium alloy. The uraniunn body is then immersed in the mixture obtained and the temperature is raised to between 425 and 600 deg C. The silicon is dissolved and deposits as a uranium-silicon compound on the uranium body.

Rapid Covalent Modification of Silicon Oxide Surfaces through Microwave-Assisted Reactions with Alcohols.

PubMed

Lee, Austin W H; Gates, Byron D

2016-07-26

We demonstrate the method of a rapid covalent modification of silicon oxide surfaces with alcohol-containing compounds with assistance by microwave reactions. Alcohol-containing compounds are prevalent reagents in the laboratory, which are also relatively easy to handle because of their stability against exposure to atmospheric moisture. The condensation of these alcohols with the surfaces of silicon oxides is often hindered by slow reaction kinetics. Microwave radiation effectively accelerates this condensation reaction by heating the substrates and/or solvents. A variety of substrates were modified in this demonstration, such as silicon oxide films of various thicknesses, glass substrates such as microscope slides (soda lime), and quartz. The monolayers prepared through this strategy demonstrated the successful formation of covalent surface modifications of silicon oxides with water contact angles of up to 110° and typical hysteresis values of 2° or less. An evaluation of the hydrolytic stability of these monolayers demonstrated their excellent stability under acidic conditions. The techniques introduced in this article were successfully applied to tune the surface chemistry of silicon oxides to achieve hydrophobic, oleophobic, and/or charged surfaces.

Photovoltaic applications of Compound Parabolic Concentrator (CPC)

NASA Technical Reports Server (NTRS)

Winston, R.

1975-01-01

The use of a compound parabolic concentrator as field collector, in conjunction with a primary focusing concentrator for photovoltaic applications is studied. The primary focusing concentrator can be a parabolic reflector, an array of Fresnel mirrors, a Fresnel lens or some other lens. Silicon solar cell grid structures are proposed that increase efficiency with concentration up to 10 suns. A ray tracing program has been developed to determine energy distribution at the exit of a compound parabolic concentrator. Projected total cost of a CPC/solar cell system will be between 4 and 5 times lower than for flat plate silicon cell arrays.

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.

Production of mullite fibers

NASA Technical Reports Server (NTRS)

Tucker, Dennis S. (Inventor); Sparks, J. Scott (Inventor)

1991-01-01

Disclosed here is a process for making mullite fibers wherein a hydrolizable silicon compound and an aluminum compound in the form of a difunctional aluminum chelate are hydrolized to form sols using water and an alcohol with a catalytic amount of hydrochloric acid. The sols are mixed in a molar ratio of aluminum to silicon of 3 to 1 and, under polycondensation conditions, a fibrous gel is formed. From this gel the mullite fibers can be produced.

Nanoscale doping of compound semiconductors by solid phase dopant diffusion

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

Ahn, Jaehyun, E-mail: jaehyun.ahn@utexas.edu; Koh, Donghyi; Roy, Anupam

2016-03-21

Achieving damage-free, uniform, abrupt, ultra-shallow junctions while simultaneously controlling the doping concentration on the nanoscale is an ongoing challenge to the scaling down of electronic device dimensions. Here, we demonstrate a simple method of effectively doping ΙΙΙ-V compound semiconductors, specifically InGaAs, by a solid phase doping source. This method is based on the in-diffusion of oxygen and/or silicon from a deposited non-stoichiometric silicon dioxide (SiO{sub x}) film on InGaAs, which then acts as donors upon activation by annealing. The dopant profile and concentration can be controlled by the deposited film thickness and thermal annealing parameters, giving active carrier concentration ofmore » 1.4 × 10{sup 18 }cm{sup −3}. Our results also indicate that conventional silicon based processes must be carefully reviewed for compound semiconductor device fabrication to prevent unintended doping.« less

Highly crosslinked silicon polymers for gas chromatography columns

NASA Technical Reports Server (NTRS)

Shen, Thomas C. (Inventor)

1994-01-01

A new highly crosslinked silicone polymer particle for gas chromatography application and a process for synthesizing such copolymer are described. The new copolymer comprises vinyltriethoxysilane and octadecyltrichlorosilane. The copolymer has a high degree of crosslinking and a cool balance of polar to nonpolar sites in the porous silicon polymer assuring fast separation of compounds of variable polarity.

Microminiature gas chromatograph

DOEpatents

Yu, C.M.

1996-12-10

A microminiature gas chromatograph ({mu}GC) comprising a least one silicon wafer, a gas injector, a column, and a detector. The gas injector has a normally closed valve for introducing a mobile phase including a sample gas in a carrier gas. The valve is fully disposed in the silicon wafer(s). The column is a microcapillary in silicon crystal with a stationary phase and is mechanically connected to receive the mobile phase from the gas injector for the molecular separation of compounds in the sample gas. The detector is mechanically connected to the column for the analysis of the separated compounds of sample gas with electronic means, e.g., ion cell, field emitter and PIN diode. 7 figs.

Influence of silicon defects on the adsorption of thiophene-like compounds on polycyclic aromatic hydrocarbons: a theoretical study using thiophene + coronene as the simplest model.

PubMed

Galano, Annia

2007-03-08

Physisorption and chemisorption processes of thiophene on coronene and 2Si-coronene have been studied using density functional theory and MP2 methods. These systems have been chosen as the simplest models to describe the adsorption of thiophene-like compounds on polycyclic aromatic hydrocarbons (PAHs). The calculated data suggest that the presence of silicon atoms in PAHs could favor their interaction with thiophene and similar compounds. Small stabilization energies have been found for several physisorbed complexes. The thiophene chemisorption on coronene seems very unlikely to occur, while that on 2Si-coronene leads to addition products which are very stable, with respect to the isolated reactants. These chemisorption processes were found to be exoergic (DeltaG < 0) in the gas phase and in the nonpolar liquid phase. The results reported in this work suggest that silicon defects on extended polycyclic aromatic hydrocarbons, such as graphite, soot, and large-diameter carbon nanotubes, could make them useful in the removal processes of aromatic sulfur compounds from oil hydrocarbons.

The Reactivity of Transition Metal-Silicon Compounds

DTIC Science & Technology

1988-08-08

light, and appear to follow both thermal and photochemical pathways. Compounds 9 and 10 are efficient acetylene polymerization catalysts . The scandium...containing both silicon and an early-transition- metal, Previously this field was quite undeveloped, therefore we surveyed a number ( approaches to...15- C5Me5)Ta(SiMe 3)C13 ," J Arnold and T D Tilley, J Am Chem Soc, 107, 6409 (1985) "Tetrahedral Lewis Base Adducts of an Acyl. Preparation and X-ray

Metal organic chemical vapor deposition of 111-v compounds on silicon

DOEpatents

Vernon, Stanley M.

1986-01-01

Expitaxial composite comprising thin films of a Group III-V compound semiconductor such as gallium arsenide (GaAs) or gallium aluminum arsenide (GaAlAs) on single crystal silicon substrates are disclosed. Also disclosed is a process for manufacturing, by chemical deposition from the vapor phase, epitaxial composites as above described, and to semiconductor devices based on such epitaxial composites. The composites have particular utility for use in making light sensitive solid state solar cells.

Wet-chemical systems and methods for producing black silicon substrates

DOEpatents

Yost, Vernon; Yuan, Hao-Chih; Page, Matthew

2015-05-19

A wet-chemical method of producing a black silicon substrate. The method comprising soaking single crystalline silicon wafers in a predetermined volume of a diluted inorganic compound solution. The substrate is combined with an etchant solution that forms a uniform noble metal nanoparticle induced Black Etch of the silicon wafer, resulting in a nanoparticle that is kinetically stabilized. The method comprising combining with an etchant solution having equal volumes acetonitrile/acetic acid:hydrofluoric acid:hydrogen peroxide.

Checking Surface Contours

NASA Technical Reports Server (NTRS)

Velega, D.

1983-01-01

Rubber impressions viewed with optical comparator. Simple mold constructed from aluminum sheet or any other easily shaped material compatible with silicone rubber ingredients. Mold placed over surface to be measured. Newly-mixed silicone rubber compound poured in mold and allowed to cure.

Neutral six-coordinate bis(dithiocarbamato)silicon(iv) complexes with an SiCl2S4 skeleton.

PubMed

Baus, Johannes A; Tacke, Reinhold

2017-07-11

Treatment of SiCl 4 with lithium dithiocarbamates of the formula type Li[R 2 NCS 2 ] (R = Ph, iPr) in a molar ratio of 1 : 2 afforded the respective six-coordinate silicon(iv) complexes [Ph 2 NCS 2 ] 2 SiCl 2 (3) and [iPr 2 NCS 2 ] 2 SiCl 2 (4), which were isolated as the solvates 3·MeCN and 4·MeCN. Compounds 3·MeCN and 4·MeCN were structurally characterised by single-crystal X-ray diffraction and multinuclear NMR spectroscopic studies in the solid state and in solution. In this study, dithiocarbamato ligands were implemented in silicon coordination chemistry for the first time. Compounds 3 and 4 represent the first six-coordinate silicon(iv) complexes with an SiCl 2 S 4 skeleton.

Stereochemistry of silicon in oxygen-containing compounds

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

Serezhkin, V. N., E-mail: Serezhkin@samsu.ru; Urusov, V. S.

2017-01-15

Specific stereochemical features of silicon in oxygen-containing compounds, including hybrid silicates with all oxygen atoms of SiO{sub n} groups ({sub n} = 4, 5, or 6) entering into the composition of organic anions or molecules, are described by characteristics of Voronoi—Dirichlet polyhedra. It is found that in rutile-like stishovite and post-stishovite phases with the structures similar to those of СаСl{sub 2}, α-PbO{sub 2}, or pyrite FeS{sub 2}, the volume of Voronoi—Dirichlet polyhedra of silicon and oxygen atoms decreases linearly with pressure increasing to 268 GPa. Based on these results, the possibility of formation of new post-stishovite phases is shown, namely,more » the fluorite-like structure (transition predicted at ~400 GPa) and a body-centered cubic lattice with statistical arrangement of silicon and oxygen atoms (~900 GPa).« less

Phase diagram and electrical behavior of silicon-rich iridium silicide compounds

NASA Technical Reports Server (NTRS)

Allevato, C. E.; Vining, Cronin B.

1992-01-01

The iridium-silicon phase diagram on the silicon-rich side was investigated by means of X-ray powder diffraction, density, differential thermal analysis, metalography, microprobe analysis, and electrical resistivity. Attempts were made to prepare eight previously reported silicon-rich iridium silicide compounds by arc melting and Bridgman-like growth. However, microprobe analysis identified only four distinct compositions: IrSi, Ir3Si4, Ir3Si5 and IrSi sub about 3. The existence of Ir4Si5 could not be confirmed in this study, even though the crystal structure has been previously reported. Differential thermal analysis (DTA) in conjunction with X-ray powder diffraction confirm polymorphism in IrSi sub about 3, determined to have orthorhombic and monoclinic unit cells in the high and low temperature forms. A eutectic composition alloy of 83 +/- 1 atomic percent silicon was observed between IrSi sub about 3 and silicon. Ir3Si4 exhibits distinct metallic behavior while Ir3Si5 is semiconducting. Both and IrSi and IrSi sub about 3 exhibit nearly temperature independent electrical resistivities on the order of 5-10 x 10 exp -6 ohms-m.

A green procedure using ozone for Cleaning-in-Place in the beverage industry.

PubMed

Nishijima, Wataru; Okuda, Tetsuji; Nakai, Satoshi; Okada, Mitsumasa

2014-06-01

Cleaning-in-Place (CIP) in the beverage industry is typically carried out in production lines with alkaline and acidic solutions with detergents. This cleaning not only produces alkaline and acidic wastewater with detergents but also takes significant time. One of the important targets for CIP is adsorbed odorous compounds on gaskets, hence, we have tried to establish a rapid and green CIP process to remove traces of such compounds, especially d-limonene, an odorous component of orange juice, using two approaches; an ozone cleaning method and a change of gasket material from ethylene propylene diene monomer (EPDM) rubber to silicone rubber. By changing the gasket material from EPDM rubber to silicone rubber, the removability of d-limonene by typical alkaline and acidic cleanings with detergents was improved. However, complete removal of 4 mg g(-1) of d-limonene on both EPDM and silicone gaskets could not be achieved even using a series of conventional cleaning procedures that included alkaline and acidic cleaning for 220 min. Ozone treatment dramatically improved the removability of d-limonene, removing 87% from the EPDM gasket at 60 min and 100% from the silicone gasket at 30 min. The combination of the silicone gasket and ozone treatment resulted in the most effective cleaning. The main removal mechanism for ozone treatment was confirmed to be oxidation by molecular ozone. Effectiveness of changing the gasket material from EPDM rubber to silicone rubber in reducing residual amounts of odorous compounds adsorbed on the gaskets was also confirmed for furfural and 4-vinylguaiacol. Copyright © 2014 Elsevier Ltd. All rights reserved.

Using silicone wristbands to evaluate preschool children’s exposure to flame retardants

PubMed Central

Kile, Molly L.; Scott, Richard P.; O’Connell, Steven G.; Lipscomb, Shannon; MacDonald, Megan; McClelland, Megan; Anderson, Kim A.

2016-01-01

Silicone wristbands can be used as passive sampling tools for measuring personal environmental exposure to organic compounds. Due to the lightweight and simple design, the wristband may be a useful technique for measuring children’s exposure. In this study, we tested the stability of flame retardant compounds in silicone wristbands and developed an analytical approach for measuring 41 flame retardants in the silicone wristband in order to evaluate exposure to these compounds in preschool-aged children. To evaluate the robustness of using wristbands to measure flame retardants, we evaluated the stability of 3 polybrominated diphenyl ethers (BDEs), and 2 organophosphate flame retardants (OPFRs) in wristbands over 84 days and did not find any evidence of significant loss over time at either 4 or −20°C (p > 0.16). We recruited a cohort of 92 preschool aged children in Oregon to wear the wristband for 7 days in order to characterize children’s acceptance of the technology, and to characterize their exposure to flame retardants. Seventy-seven parents returned the wristbands for analysis of 35 BDEs, 4 OPFRs, and 2 other brominated flame retardants although 5 were excluded from the exposure assessment due to protocol deviations (n=72). A total of 20 compounds were detected above the limit of quantitation, and 11 compounds including 4 OPFRs and 7 BDEs were detected in over 60% of the samples. Children’s gender, age, race, recruitment site, and family context were not significantly associated with returning wristbands or compliance with protocols. Comparisons between flame retardant data and socio-demographic information revealed significant differences in total exposures to both ΣBDEs and ΣOPFRs based on age of house, vacuuming frequency, and family context. These results demonstrate that preschool children in Oregon are exposed to BDEs that are no longer being produced in the United States and to OPFRs that have been used as an alternative to polybrominated compounds. Silicone wristbands were well tolerated by young children and were useful for characterizing personal exposure to flame retardants that were not bound to particulate matter. PMID:26945619

Silicone Resin Applications for Ceramic Precursors and Composites

PubMed Central

Narisawa, Masaki

2010-01-01

This article reviews the applications of silicone resins as ceramic precursors. The historical background of silicone synthesis chemistry is introduced to explain the production costs and supply availability of various silicones. Thermal degradation processes of silicones are classified in terms of the main chain structure and cyclic oligomer expulsion process, which determine the resulting ceramic yield and the chemical composition. The high temperature decomposition of Si-O-C beyond 1,400 °C in an inert atmosphere and formation of a protective silica layer on material surfaces beyond 1,200 °C in an oxidative atmosphere are discussed from the viewpoints of the wide chemical composition of the Si-O-C materials. Applications of the resins for binding agents, as starting materials for porous ceramics, matrix sources with impregnation, fiber spinning and ceramic adhesions are introduced. The recent development of the process of filler or cross-linking agent additions to resin compounds is also introduced. Such resin compounds are useful for obtaining thick coatings, MEMS parts and bulk ceramics, which are difficult to obtain by pyrolysis of simple organometallic precursors without additives.

Double stabilization of nanocrystalline silicon: a bonus from solvent

NASA Astrophysics Data System (ADS)

Kolyagin, Y. G.; Zakharov, V. N.; Yatsenko, A. V.; Paseshnichenko, K. A.; Savilov, S. V.; Aslanov, L. A.

2016-01-01

Double stabilization of the silicon nanocrystals was observed for the first time by 29Si and 13C MAS NMR spectroscopy. The role of solvent, 1,2-dimethoxyethane (glyme), in formation and stabilization of silicon nanocrystals as well as mechanism of modification of the surface of silicon nanocrystals by nitrogen-heterocyclic carbene (NHC) was studied in this research. It was shown that silicon nanocrystals were stabilized by the products of cleavage of the C-O bonds in ethers and similar compounds. The fact of stabilization of silicon nanoparticles with NHC ligands in glyme was experimentally detected. It was demonstrated that MAS NMR spectroscopy is rather informative for study of the surface of silicon nanoparticles but it needs very pure samples.

Hybrid integration of III-V semiconductor lasers on silicon waveguides using optofluidic microbubble manipulation

PubMed Central

Jung, Youngho; Shim, Jaeho; Kwon, Kyungmook; You, Jong-Bum; Choi, Kyunghan; Yu, Kyoungsik

2016-01-01

Optofluidic manipulation mechanisms have been successfully applied to micro/nano-scale assembly and handling applications in biophysics, electronics, and photonics. Here, we extend the laser-based optofluidic microbubble manipulation technique to achieve hybrid integration of compound semiconductor microdisk lasers on the silicon photonic circuit platform. The microscale compound semiconductor block trapped on the microbubble surface can be precisely assembled on a desired position using photothermocapillary convective flows induced by focused laser beam illumination. Strong light absorption within the micro-scale compound semiconductor object allows real-time and on-demand microbubble generation. After the assembly process, we verify that electromagnetic radiation from the optically-pumped InGaAsP microdisk laser can be efficiently coupled to the single-mode silicon waveguide through vertical evanescent coupling. Our simple and accurate microbubble-based manipulation technique may provide a new pathway for realizing high precision fluidic assembly schemes for heterogeneously integrated photonic/electronic platforms as well as microelectromechanical systems. PMID:27431769

Lifetime Extension of the Gas Discharge Detectors with Plasma Etching of Silicon Deposits in 80%CF4 + 20%CO2

NASA Astrophysics Data System (ADS)

Gavrilov, G. E.; Vakhtel, V. M.; Maysuzenko, D. A.; Tavtorkina, T. A.; Fetisov, A. A.; Shvetsova, N. Yu.

2017-12-01

A method of elimination of silicon compounds from the anode wire of an aged proportional counter is presented. The aging of a counter with a 70%Ar + 30%CO2 and a 60%Ar + 30%CO2 + 10%CF4 working mixture was stimulated by a 90Sr β source. To accelerate the process of aging, the gas mixture flow to the counter was supplied through a pipe with RTV coated wall. As a result, the amplitude of the signal decreased 70% already at accumulated charge of Q = 0.03 C/cm. The etching of the silicon compounds on the wire surface with an 80%CF4 + 20%CO2 gas mixture discharge led to full recovery of the operating characteristics of detector and an increase in the lifetime. A scanning electron microscopy and X-ray spectroscopy analysis of the recovered wire surface were performed. In accordance with the results, a good quality of wire cleaning from SiO2 compounds was obtained.

Characterization and Application of Passive Samplers for Monitoring of Pesticides in Water.

PubMed

Ahrens, Lutz; Daneshvar, Atlasi; Lau, Anna E; Kreuger, Jenny

2016-08-03

Five different water passive samplers were calibrated under laboratory conditions for measurement of 124 legacy and current used pesticides. This study provides a protocol for the passive sampler preparation, calibration, extraction method and instrumental analysis. Sampling rates (RS) and passive sampler-water partition coefficients (KPW) were calculated for silicone rubber, polar organic chemical integrative sampler POCIS-A, POCIS-B, SDB-RPS and C18 disk. The uptake of the selected compounds depended on their physicochemical properties, i.e., silicone rubber showed a better uptake for more hydrophobic compounds (log octanol-water partition coefficient (KOW) > 5.3), whereas POCIS-A, POCIS-B and SDB-RPS disk were more suitable for hydrophilic compounds (log KOW < 0.70).

Determination of silicone rubber and low-density polyethylene diffusion and polymer/water partition coefficients for emerging contaminants.

PubMed

Pintado-Herrera, Marina G; Lara-Martín, Pablo A; González-Mazo, Eduardo; Allan, Ian J

2016-09-01

There is a growing interest in assessing the concentration and distribution of new nonregulated organic compounds (emerging contaminants) in the environment. The measurement of freely dissolved concentrations using conventional approaches is challenging because of the low concentrations that may be encountered and their temporally variable emissions. Absorption-based passive sampling enables the estimation of freely dissolved concentrations of hydrophobic contaminants of emerging concern in water. In the present study, calibration was undertaken for 2 polymers, low-density polyethylene (LDPE) and silicone rubber for 11 fragrances, 5 endocrine-disrupting compounds, 7 ultraviolet (UV) filters, and 8 organophosphate flame retardant compounds. Batch experiments were performed to estimate contaminant diffusion coefficients in the polymers (Dp ), which in general decreased with increasing molecular weight. The values for fragrances, endocrine-disrupting compounds, and UV filters were in ranges similar to those previously reported for polycyclic aromatic hydrocarbons, but were 1 order of magnitude lower for organophosphate flame retardant compounds. Silicone rubber had higher Dp values than LDPE and was therefore selected for further experiments to calculate polymer/water partition coefficients (KPW ). The authors observed a positive correlation between log KPW and log octanol/water partition coefficient values. Field testing of silicone rubber passive samplers was undertaken though exposure in the River Alna (Norway) for an exposure time of 21 d to estimate freely dissolved concentration. Some fragrances and UV filters were predominant over other emerging and regulated contaminants, at levels up to 1600 ng L(-1) for galaxolide and 448 ng L(-1) for octocrylene. Environ Toxicol Chem 2016;35:2162-2172. © 2016 SETAC. © 2016 SETAC.

Fabrication of polycrystalline solar cells on low-cost substrates

NASA Technical Reports Server (NTRS)

Chu, T. L. (Inventor)

1976-01-01

A new method of producing p-n junction semiconductors for solar cells was described; the principal objective of this investigation is to reduce production costs significantly by depositing polycrystalline silicon on a relatively cheap substrate such as metallurgical-grade silicon, graphite, or steel. The silicon layer contains appropriate dopants, and the substrates are coated with a diffusion barrier of silica, borosilicate, phosphosilicate, or mixtures of these compounds.

InGaAlAsPN: A Materials System for Silicon Based Optoelectronics and Heterostructure Device Technologies

NASA Technical Reports Server (NTRS)

Broekaert, T. P. E.; Tang, S.; Wallace, R. M.; Beam, E. A., III; Duncan, W. M.; Kao, Y. -C.; Liu, H. -Y.

1995-01-01

A new material system is proposed for silicon based opto-electronic and heterostructure devices; the silicon lattice matched compositions of the (In,Ga,Al)-(As,P)N 3-5 compounds. In this nitride alloy material system, the bandgap is expected to be direct at the silicon lattice matched compositions with a bandgap range most likely to be in the infrared to visible. At lattice constants ranging between those of silicon carbide and silicon, a wider bandgap range is expected to be available and the high quality material obtained through lattice matching could enable applications such as monolithic color displays, high efficiency multi-junction solar cells, opto-electronic integrated circuits for fiber communications, and the transfer of existing 3-5 technology to silicon.

Volatile Organic Silicon Compounds in Biogases: Development of Sampling and Analytical Methods for Total Silicon Quantification by ICP-OES

PubMed Central

Julien, Jennifer; Dumont, Nathalie; Lebouil, David; Germain, Patrick

2014-01-01

Current waste management policies favor biogases (digester gases (DGs) and landfill gases (LFGs)) valorization as it becomes a way for energy politics. However, volatile organic silicon compounds (VOSiCs) contained into DGs/LFGs severely damage combustion engines and endanger the conversion into electricity by power plants, resulting in a high purification level requirement. Assessing treatment efficiency is still difficult. No consensus has been reached to provide a standardized sampling and quantification of VOSiCs into gases because of their diversity, their physicochemical properties, and the omnipresence of silicon in analytical chains. Usually, samplings are done by adsorption or absorption and quantification made by gas chromatography-mass spectrometry (GC-MS) or inductively coupled plasma-optical emission spectrometry (ICP-OES). In this objective, this paper presents and discusses the optimization of a patented method consisting in VOSiCs sampling by absorption of 100% ethanol and quantification of total Si by ICP-OES. PMID:25379538

Volatile organic silicon compounds in biogases: development of sampling and analytical methods for total silicon quantification by ICP-OES.

PubMed

Chottier, Claire; Chatain, Vincent; Julien, Jennifer; Dumont, Nathalie; Lebouil, David; Germain, Patrick

2014-01-01

Current waste management policies favor biogases (digester gases (DGs) and landfill gases (LFGs)) valorization as it becomes a way for energy politics. However, volatile organic silicon compounds (VOSiCs) contained into DGs/LFGs severely damage combustion engines and endanger the conversion into electricity by power plants, resulting in a high purification level requirement. Assessing treatment efficiency is still difficult. No consensus has been reached to provide a standardized sampling and quantification of VOSiCs into gases because of their diversity, their physicochemical properties, and the omnipresence of silicon in analytical chains. Usually, samplings are done by adsorption or absorption and quantification made by gas chromatography-mass spectrometry (GC-MS) or inductively coupled plasma-optical emission spectrometry (ICP-OES). In this objective, this paper presents and discusses the optimization of a patented method consisting in VOSiCs sampling by absorption of 100% ethanol and quantification of total Si by ICP-OES.

Joined ceramic product

DOEpatents

Henager, Jr., Charles W [Kennewick, WA; Brimhall, John L [West Richland, WA

2001-08-21

According to the present invention, a joined product is at least two ceramic parts, specifically bi-element carbide parts with a bond joint therebetween, wherein the bond joint has a metal silicon phase. The bi-element carbide refers to compounds of MC, M.sub.2 C, M.sub.4 C and combinations thereof, where M is a first element and C is carbon. The metal silicon phase may be a metal silicon carbide ternary phase, or a metal silicide.

The effect of silicone-gel on the immune response.

PubMed

Naim, J O; Lanzafame, R J; van Oss, C J

1995-01-01

Silicone materials have been used in medical applications for at least 30 years. Despite this long history of use the question whether silicones can mediate an immunological reaction that may be detrimental to the host remains unanswered. Most studies on the biocompatability of silicones conclude that silicones are chemically stable compounds, which however are often capable of eliciting a benign chronic inflammatory response. Recently, our laboratory has conducted a series of animal experiments aimed at determining the immunological adjuvancy potential of silicone-gel taken from commercial breast implants. Our previous studies have indicated that silicone-gel is a potent humoral (antibody) adjuvant. Our present studies have found that silicone-gel is capable of eliciting auto-antibodies to rat thyroglobulin and bovine collagen II. However this immune response did not produce any histological evidence of thyroiditis or arthritis. Theories to explain why silicone-gel behaves as an adjuvant are discussed along with discussion of the hypothesis on the desirability of replacing silicone-gel with a more hydrophilic material in bioimplants.

Synthesis of temperature and solvent-resistant polymers

NASA Technical Reports Server (NTRS)

Webster, J. A.; Patterson, W. J.; Moffett, R. L.; Morris, D. E.

1972-01-01

Development of silicone polymers, polyimides, and polyisocyanurates for use as insulation, coatings, or adhesives under adverse environmental conditions is discussed. Chemical structure of the organic compounds is presented. Physical and mechanical properties of the compounds are analyzed.

Synthesis of tritium breeder ceramics from metallic lithium

NASA Astrophysics Data System (ADS)

Knitter, R.; Kolb, M. H. H.; Odemer, C.

2012-01-01

For the fabrication of Li-6 enriched ceramic breeder materials for ITER, the availability of Li-6 enriched compounds is limited, and metallic Li-6 is the most widely available compound. As metallic lithium cannot be used directly in ceramic fabrication processes, we investigated different syntheses to obtain lithium orthosilicate or lithium metatitanate directly from molten lithium. In exothermic reactions of molten lithium with silicon, silica, or titania, several intermediate or precursor phases were observed under argon that could easily be transformed to the desired ceramic phases by a subsequent heat treatment under air. The reaction steps and the resulting phases were studied by differential scanning calorimetry and X-ray diffractometry. The synthesis from lithium and silicon seems to be especially suited for the production of larger quantities and has the advantage that silicon is available with a very high grade of purity.

IEEE Photovoltaic Specialists Conference, 20th, Las Vegas, NV, Sept. 26-30, 1988, Conference Record. Volumes 1 & 2

NASA Astrophysics Data System (ADS)

Various papers on photovoltaics are presented. The general topics considered include: amorphous materials and cells; amorphous silicon-based solar cells and modules; amorphous silicon-based materials and processes; amorphous materials characterization; amorphous silicon; high-efficiency single crystal solar cells; multijunction and heterojunction cells; high-efficiency III-V cells; modeling and characterization of high-efficiency cells; LIPS flight experience; space mission requirements and technology; advanced space solar cell technology; space environmental effects and modeling; space solar cell and array technology; terrestrial systems and array technology; terrestrial utility and stand-alone applications and testing; terrestrial concentrator and storage technology; terrestrial stand-alone systems applications; terrestrial systems test and evaluation; terrestrial flatplate and concentrator technology; use of polycrystalline materials; polycrystalline II-VI compound solar cells; analysis of and fabrication procedures for compound solar cells.

Method of enhancing the electronic properties of an undoped and/or N-type hydrogenated amorphous silicon film

DOEpatents

Carlson, David E.

1980-01-01

The dark conductivity and photoconductivity of an N-type and/or undoped hydrogenated amorphous silicon layer fabricated by an AC or DC proximity glow discharge in silane can be increased through the incorporation of argon in an amount from 10 to about 90 percent by volume of the glow discharge atmosphere which contains a silicon-hydrogen containing compound in an amount of from about 90 to about 10 volume percent.

Retention Indices for Frequently Reported Compounds of Plant Essential Oils

NASA Astrophysics Data System (ADS)

Babushok, V. I.; Linstrom, P. J.; Zenkevich, I. G.

2011-12-01

Gas chromatographic retention indices were evaluated for 505 frequently reported plant essential oil components using a large retention index database. Retention data are presented for three types of commonly used stationary phases: dimethyl silicone (nonpolar), dimethyl silicone with 5% phenyl groups (slightly polar), and polyethylene glycol (polar) stationary phases. The evaluations are based on the treatment of multiple measurements with the number of data records ranging from about 5 to 800 per compound. Data analysis was limited to temperature programmed conditions. The data reported include the average and median values of retention index with standard deviations and confidence intervals.

Internal energy deposition with silicon nanoparticle-assisted laser desorption/ionization (SPALDI) mass spectrometry

NASA Astrophysics Data System (ADS)

Dagan, Shai; Hua, Yimin; Boday, Dylan J.; Somogyi, Arpad; Wysocki, Ronald J.; Wysocki, Vicki H.

2009-06-01

The use of silicon nanoparticles for laser desorption/ionization (LDI) is a new appealing matrix-less approach for the selective and sensitive mass spectrometry of small molecules in MALDI instruments. Chemically modified silicon nanoparticles (30 nm) were previously found to require very low laser fluence in order to induce efficient LDI, which raised the question of internal energy deposition processes in that system. Here we report a comparative study of internal energy deposition from silicon nanoparticles to previously explored benzylpyridinium (BP) model compounds during LDI experiments. The internal energy deposition in silicon nanoparticle-assisted laser desorption/ionization (SPALDI) with different fluorinated linear chain modifiers (decyl, hexyl and propyl) was compared to LDI from untreated silicon nanoparticles and from the organic matrix, [alpha]-cyano-4-hydroxycinnamic acid (CHCA). The energy deposition to internal vibrational modes was evaluated by molecular ion survival curves and indicated that the ions produced by SPALDI have an internal energy threshold of 2.8-3.7 eV. This is slightly lower than the internal energy induced using the organic CHCA matrix, with similar molecular survival curves as previously reported for LDI off silicon nanowires. However, the internal energy associated with desorption/ionization from the silicon nanoparticles is significantly lower than that reported for desorption/ionization on silicon (DIOS). The measured survival yields in SPALDI gradually decrease with increasing laser fluence, contrary to reported results for silicon nanowires. The effect of modification of the silicon particle surface with semifluorinated linear chain silanes, including fluorinated decyl (C10), fluorinated hexyl (C6) and fluorinated propyl (C3) was explored too. The internal energy deposited increased with a decrease in the length of the modifier alkyl chain. Unmodified silicon particles exhibited the highest analyte internal energy deposition. These findings may suggest a role of the modifier as a moderator in the energy dissipation and relaxation process. The relatively low internal energy content of SPALDI-produced ions indicates that this is a "soft" desorption technique, with potential advantages in the analysis of labile compounds.

Density functional theory calculation of refractive indices of liquid-forming silicon oil compounds

NASA Astrophysics Data System (ADS)

Lee, Sanghun; Park, Sung Soo; Hagelberg, Frank

2012-02-01

A combination of quantum chemical calculation and molecular dynamics simulation is applied to compute refractive indices of liquid-forming silicon oils. The densities of these species are obtained from molecular dynamics simulations based on the NPT ensemble while the molecular polarizabilities are evaluated by density functional theory. This procedure is shown to yield results well compatible with available experimental data, suggesting that it represents a robust and economic route for determining the refractive indices of liquid-forming organic complexes containing silicon.

The behavior of SiC and Si3N4 ceramics in mixed oxidation/chlorination environments

NASA Technical Reports Server (NTRS)

Marra, John E.; Kreidler, Eric R.; Jacobson, Nathan S.; Fox, Dennis S.

1989-01-01

The behavior of silicon-based ceramics in mixed oxidation/chlorination environments was studied. High pressure mass spectrometry was used to quantitatively identify the reaction products. The quantitative identification of the corrosion products was coupled with thermogravimetric analysis and thermodynamic equilibrium calculations run under similar conditions in order to deduce the mechanism of corrosion. Variations in the behavior of the different silicon-based materials are discussed. Direct evidence of the existence of silicon oxychloride compounds is presented.

Graphene optical modulator

NASA Astrophysics Data System (ADS)

Liu, Ming; Yin, Xiaobo; Wang, Feng; Zhang, Xiang

2011-10-01

Data communications have been growing at a speed even faster than Moore's Law, with a 44-fold increase expected within the next 10 years. Data Transfer on such scale would have to recruit optical communication technology and inspire new designs of light sources, modulators, and photodetectors. An ideal optical modulator will require high modulation speed, small device footprint and large operating bandwidth. Silicon modulators based on free carrier plasma dispersion effect and compound semiconductors utilizing direct bandgap transition have seen rapid improvement over the past decade. One of the key limitations for using silicon as modulator material is its weak refractive index change, which limits the footprint of silicon Mach-Zehnder interferometer modulators to millimeters. Other approaches such as silicon microring modulators reduce the operation wavelength range to around 100 pm and are highly sensitive to typical fabrication tolerances and temperature fluctuations. Growing large, high quality wafers of compound semiconductors, and integrating them on silicon or other substrates is expensive, which also restricts their commercialization. In this work, we demonstrate that graphene can be used as the active media for electroabsorption modulators. By tuning the Fermi energy level of the graphene layer, we induced changes in the absorption coefficient of graphene at communication wavelength and achieve a modulation depth above 3 dB. This integrated device also has the potential of working at high speed.

Adjustable high emittance gap filler. [reentry shielding for space shuttle vehicles

NASA Technical Reports Server (NTRS)

Leiser, D. B.; Stewart, D. A.; Smith, M.; Estrella, C. A.; Goldstein, H. E. (Inventor)

1981-01-01

A flexible, adjustable refractory filler is disclosed for filling gaps between ceramic tiles forming the heat shield of a space shuttle vehicle, to protect its aluminum skin during atmospheric reentry. The easily installed and replaced filler consists essentially of a strip of ceramic cloth coated, at least along both its longitudinal edges with a room temperature vulcanizable silicone rubber compound with a high emittance colored pigment. The filler may have one or more layers as the gap width requires. Preferred materials are basket weave aluminoborosilicate cloth, and a rubber compounded with silicon tetraboride as the emittance agent and finely divided borosilicate glass containing about 7.5% B2O3 as high temperature binder. The filler cloth strip or tape is cut to proper width and length, inserted into the gap, and fastened with previously applied drops of silicone rubber adhesive.

Diatomite releases silica during spirit filtration.

PubMed

Gómez, J; Gil, M L A; de la Rosa-Fox, N; Alguacil, M

2014-09-15

The purpose of this study was to ascertain whether diatomite is an inert filter aid during spirit filtration. Surely, any compound with a negative effect on the spirit composition or the consumer's health could be dissolved. In this study different diatomites were treated with 36% vol. ethanol/water mixtures and the amounts and structures of the extracted compounds were determined. Furthermore, Brandy de Jerez was diatomite- and membrane-filtered at different temperatures and the silicon content was analysed. It was found that up to 0.36% by weight of diatomite dissolved in the aqueous ethanol and amorphous silica, in the form of hollow spherical microparticles, was the most abundant component. Silicon concentrations in Brandy de Jerez increased by up to 163.0% after contact with diatomite and these changes were more marked for calcined diatomite. In contrast, reductions of more than 30% in silicon concentrations were achieved after membrane filtration at low temperatures. Copyright © 2014 Elsevier Ltd. All rights reserved.

A stable silicon(0) compound with a Si=Si double bond.

PubMed

Wang, Yuzhong; Xie, Yaoming; Wei, Pingrong; King, R Bruce; Schaefer, Henry F; von R Schleyer, Paul; Robinson, Gregory H

2008-08-22

Dative, or nonoxidative, ligand coordination is common in transition metal complexes; however, this bonding motif is rare in compounds of main group elements in the formal oxidation state of zero. Here, we report that the potassium graphite reduction of the neutral hypervalent silicon-carbene complex L:SiCl4 {where L: is:C[N(2,6-Pri2-C6H3)CH]2 and Pri is isopropyl} produces L:(Cl)Si-Si(Cl):L, a carbene-stabilized bis-silylene, and L:Si=Si:L, a carbene-stabilized diatomic silicon molecule with the Si atoms in the formal oxidation state of zero. The Si-Si bond distance of 2.2294 +/- 0.0011 (standard deviation) angstroms in L:Si=Si:L is consistent with a Si=Si double bond. Complementary computational studies confirm the nature of the bonding in L:(Cl)Si-Si(Cl):L and L:Si=Si:L.

Assessment of silicone as support to investigate the transformation routes of organic chemicals under environmental conditions and UV exposure. Application to selected fungicides.

PubMed

Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Cela, R

2013-05-01

The suitability of bulk silicone as support to follow the degradation of chemical compounds under environmental conditions and UV radiation is illustrated selecting three fungicides (fenhexamid, FEN; triadimenol, TRI and difenoconazole, DIF) as model compounds. These precursor species were first absorbed in silicone supports (10 mm length × 2 mm i.d. and 0.5 mm thickness) and then kept outdoors for several days (up to 2 months) or exposed to UV radiation (254 nm), from a low pressure mercury lamp, in the laboratory. Degradation of precursor fungicides and by-products formation was followed by liquid chromatography (LC) quadrupole time-of-flight (QTOF) mass spectrometry (MS), after desorption of silicone supports using 0.5 mL of acetonitrile. Half-lives (t(1/2)) measured under UV exposure varied from 5 to 100 min. As regards environmental conditions, the most stable fungicide was DIF, degraded by just 15 % after 2 months; whereas, t(1/2) values of 30 and 83 h were calculated for FEN during summer and autumn, respectively. Supports contained by-products arising from precursor species through de-chlorination, cleavage, hydroxylation, intra-molecular cyclation and oligomerization reactions. Most of them have been previously identified in soil surface, vegetable leaves and water after application of fungicides in agriculture fields. The low cost of silicone tubes (ca. 0.4 Euros), added to their excellent chemical stability and capability to retain precursor species and their by-products, make them ideal supports to follow the transformation routes of organic compounds under environmental and simulated conditions, even for relatively stable species with t(1/2) in the range of weeks or months.

The Effect of Chilling and Ce Addition on the Microstructure and Mechanical Properties of Al-23Si Alloy

NASA Astrophysics Data System (ADS)

Vijeesh, V.; Narayan Prabhu, K.

2017-01-01

The present work involves the study of the effect of varying concentration of Ce addition on microstructure and mechanical properties of Al-23%Si alloys. Melt-treated alloys were solidified in copper, brass, stainless steel molds to assess the effect of cooling rate. The effect on microstructure was assessed by measuring the fineness of primary silicon and eutectic silicon particle characteristics. The Ce melt treatment transformed the coarse and irregular primary silicon into refined polyhedral silicon crystals, and the effect was more significant at higher cooling rates. Although the melt treatment had refined the eutectic silicon at lower cooling rates, it did not show any considerable effect on the eutectic silicon at higher cooling rates. The mechanical properties of the alloy increased significantly with increase in cooling rates and cerium concentration. Analysis of the results and literature reveals that the refined primary silicon was formed as a result of an invariant reaction between Ce compounds and primary silicon at higher temperatures.

Development of a model and computer code to describe solar grade silicon production processes

NASA Technical Reports Server (NTRS)

Srivastava, R.; Gould, R. K.

1979-01-01

Mathematical models, and computer codes based on these models were developed which allow prediction of the product distribution in chemical reactors in which gaseous silicon compounds are converted to condensed phase silicon. The reactors to be modeled are flow reactors in which silane or one of the halogenated silanes is thermally decomposed or reacted with an alkali metal, H2 or H atoms. Because the product of interest is particulate silicon, processes which must be modeled, in addition to mixing and reaction of gas-phase reactants, include the nucleation and growth of condensed Si via coagulation, condensation, and heterogeneous reaction.

Electronuclear paths in the nuclear conversion of molecular hydrogen in silicon

NASA Astrophysics Data System (ADS)

Ilisca, Ernest; Ghiglieno, Filippo

2017-01-01

The ortho-para conversion of hydrogen molecules oscillating inside tetrahedral cages of silicon compounds relies on the interaction of the nuclear protons with the silicon electrons. At each collision against the cage hard walls, the electron repulsion changes the molecular rotation while projecting a valence electron in the antibonding molecular state dressed by a group of conduction ones. That «bridge» facilitates the hyperfine contact of the electrons with the protons. At room temperature, the angular momentum transfer is enhanced by electron fluctuations that overcome the silicon gap and accelerate the nuclear rates by more than one order of magnitude.

Solution immersed silicon (SIS)-based biosensors: a new approach in biosensing.

PubMed

Diware, M S; Cho, H M; Chegal, W; Cho, Y J; Jo, J H; O, S W; Paek, S H; Yoon, Y H; Kim, D

2015-02-07

A novel, solution immersed silicon (SIS)-based sensor has been developed which employs the non-reflecting condition (NRC) for a p-polarized wave. The SIS sensor's response is almost independent of change in the refractive index (RI) of a buffer solution (BS) which makes it capable of measuring low-concentration and/or low-molecular-weight compounds.

Stir bar sorptive extraction with EG-Silicone coating for bisphenols determination in personal care products by GC-MS.

PubMed

Cacho, Juan Ignacio; Campillo, Natalia; Viñas, Pilar; Hernández-Córdoba, Manuel

2013-05-05

An easy to perform analytical method for the determination of three bisphenol compounds (BPs) in commonly used personal care products (PCPs) is presented. Ethylene glycol-silicone (EG-Silicone) coated stir bars, which have recently become commercially available, are evaluated in this study for the simultaneous determination of bisphenol A (BPA), bisphenol F (BPF) and bisphenol Z (BPZ) by stir bar sorptive extraction (SBSE) in combination with thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). This new sorptive extraction phase allows the analysis of these compounds without any previous derivatization procedure. Different parameters affecting both SBSE extraction and thermal desorption were carefully optimized, using experimental designs based on the Taguchi orthogonal arrays. The procedure was applied to analyzing easily bought PCPs, providing detection limits of about 8 ng g(-1), with precisions lower than 11% in terms of relative standard deviation. Recovery studies performed at two different concentration levels provided satisfactory values for all the compounds. The analyzed personal care samples contained BPA at concentration levels ranging from 30.9 to 88.3 ng g(-1). Copyright © 2013 Elsevier B.V. All rights reserved.

Fabrication of semiconductor-polymer compound nonlinear photonic crystal slab with highly uniform infiltration based on nano-imprint lithography technique.

PubMed

Qin, Fei; Meng, Zi-Ming; Zhong, Xiao-Lan; Liu, Ye; Li, Zhi-Yuan

2012-06-04

We present a versatile technique based on nano-imprint lithography to fabricate high-quality semiconductor-polymer compound nonlinear photonic crystal (NPC) slabs. The approach allows one to infiltrate uniformly polystyrene materials that possess large Kerr nonlinearity and ultrafast nonlinear response into the cylindrical air holes with diameter of hundred nanometers that are perforated in silicon membranes. Both the structural characterization via the cross-sectional scanning electron microscopy images and the optical characterization via the transmission spectrum measurement undoubtedly show that the fabricated compound NPC samples have uniform and dense polymer infiltration and are of high quality in optical properties. The compound NPC samples exhibit sharp transmission band edges and nondegraded high quality factor of microcavities compared with those in the bare silicon PC. The versatile method can be expanded to make general semiconductor-polymer hybrid optical nanostructures, and thus it may pave the way for reliable and efficient fabrication of ultrafast and ultralow power all-optical tunable integrated photonic devices and circuits.

Incorporation of capsaicin in silicone coatings for enhanced antifouling performance

NASA Astrophysics Data System (ADS)

Reddy Jaggari, Karunakar; Zhang Newby, Bi-Min

2002-03-01

Successful use of capsaicin as insect and animal repellant propelled us to use it as a possible antifouling agent. Its non-toxic, non-biocidal, non-leaching properties make it a viable alternative to organotin compounds. In order to optimize the anti-fouling performance of the coating, silicone, the most effective foul-release marine coating, was chosen as the carrier. We have incorporated capsaicin into silicone coating, by both bulk entrapment and surface immobilization. Contact angle measurements on capsaicin-incorporated silicone exhibited an increase in wettability, owing to the presence of capsaicin. FTIR study further confirmed the incorporation of capsaicin in silicone. Bacterial attachment studies were conducted using lake Erie water. While bacteria liberally inhabited the control coating, their presence on the capsaicin-incorporated coating was found to be minimal. These preliminary studies indicate that capsaicin incorporated silicone could be a viable environment friendly alternative to currently used antifouling coatings.

Determination of siloxanes and VOC in landfill gas and sewage gas by canister sampling and GC-MS/AES analysis

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

Schweigkofler, M.; Niessner, R.

1999-10-15

Biogases such as landfill gas and sewage gas undergo a combustion process which is generating electric energy. Since several trace compounds such as siloxanes (also halogenated and sulfur compounds) are known to cause severe problems to these gas combustion engines, they are of particular interest. In this work, a new technique for sampling, identification, and quantification of siloxanes and volatile organic carbon (VOC) in landfill gas and sewage gas is presented. After sample collection using evacuated stainless steel canisters biogas was analyzed by gas chromatography-mass spectrometry/atomic emission spectroscopy (GC-MS/AES). Using gas canisters, the sampling process was simplified (no vacuum pumpmore » needed), and multiple analysis was possible. The simultaneous application of MSD and AED allowed a rapid screening of silicon compounds in the complex biogases. Individual substances were identified independently both by MSD analysis and by determination of their elemental constitution. Quantification of trace compounds was achieved using a 30 component external standard containing siloxanes, organochlorine and organosulfur compounds, alkanes, terpenes, and aromatic compounds. Precision, linearity, and detection limits have been studied. In real samples, concentrations of silicon containing compounds (trimethylsilanol, hexamethyldisiloxane, octamethyltrisiloxane, decamethyltetrasiloxane, hexamethylcyclotrisiloxane, octamethylcyclotetrasilioxane, decamethylcyclopentasiloxane, and dodecamethylcyclohexasiloxane) in the mg/m{sub 3} range have been observed.« less

[Determination of organotin compounds in plastic products by GC/MS after ethyl derivatization with sodium tetraethylborate].

PubMed

Ohno, Hiroyuki; Suzuki, Masako; Nakashima, Shigehito; Aoyama, Taiki; Mitani, Kazunori

2002-08-01

A simultaneous determination method for 9 organotin compounds in polyvinyl chloride (PVC) and silicone products used as kitchen utensils and food packages was developed using ethyl derivatization with sodium tetraethylborate (NaBEt4). Organotin compounds were extracted with acetone-hexane (3:7) from the samples after acidification and the extract was filtered and concentrated at under 40 degrees C. After centrifugal separation, these compounds were derivatized with 2% NaBEt4 solution and determined by GC/MS. This method was applicable for simple routine analysis. Recoveries of spiked compounds were 49.1-118.1% for 3 PVC products and 88.8-102.2% for a siliconized paper. Monooctyltin, dioctyltin and trioctyltin compounds were found in all PVC food containers at the levels of 123-1,380 micrograms/g, 1,770-13,200 micrograms/g and 6.6-139 micrograms/g, respectively. They also were found in 3 gloves, 5 spouts, 1 hose and 5 pipes. Some PVC products contained monomethyltin, dimethyltin, trimethyltin, monobutyltin and dibutyltin compounds at the levels of 97.3-433 micrograms/g, 96.5-5,120 micrograms/g, 8.5-24.9 micrograms/g, 1.2-852 micrograms/g and 1.2-29.4 micrograms/g, respectively.

LiBSi2: a tetrahedral semiconductor framework from boron and silicon atoms bearing lithium atoms in the channels.

PubMed

Zeilinger, Michael; van Wüllen, Leo; Benson, Daryn; Kranak, Verina F; Konar, Sumit; Fässler, Thomas F; Häussermann, Ulrich

2013-06-03

Silicon swallows up boron: The novel open tetrahedral framework structure (OTF) of the Zintl phase LiBSi2 was made by applying high pressure to a mixture of LiB and elemental silicon. The compound represents a new topology in the B-Si net (called tum), which hosts Li atoms in the channels (see picture). LiBSi2 is the first example where B and Si atoms form an ordered common framework structure with B engaged exclusively in heteronuclear B-Si contacts.

Fluoroethylene Carbonate as a Directing Agent in Amorphous Silicon Anodes: Electrolyte Interface Structure Probed by Sum Frequency Vibrational Spectroscopy and Ab Initio Molecular Dynamics.

PubMed

Horowitz, Yonatan; Han, Hui-Ling; Soto, Fernando A; Ralston, Walter T; Balbuena, Perla B; Somorjai, Gabor A

2018-02-14

Fluorinated compounds are added to carbonate-based electrolyte solutions in an effort to create a stable solid electrolyte interphase (SEI). The SEI mitigates detrimental electrolyte redox reactions taking place on the anode's surface upon applying a potential in order to charge (discharge) the lithium (Li) ion battery. The need for a stable SEI is dire when the anode material is silicon as silicon cracks due to its expansion and contraction upon lithiation and delithiation (charge-discharge) cycles, consequently limiting the cyclability of a silicon-based battery. Here we show the molecular structures for ethylene carbonate (EC): fluoroethylene carbonate (FEC) solutions on silicon surfaces by sum frequency generation (SFG) vibrational spectroscopy, which yields vibrational spectra of molecules at interfaces and by ab initio molecular dynamics (AIMD) simulations at open circuit potential. Our AIMD simulations and SFG spectra indicate that both EC and FEC adsorb to the amorphous silicon (a-Si) through their carbonyl group (C═O) oxygen atom with no further desorption. We show that FEC additives induce the reorientation of EC molecules to create an ordered, up-right orientation of the electrolytes on the Si surface. We suggest that this might be helpful for Li diffusion under applied potential. Furthermore, FEC becomes the dominant species at the a-Si surface as the FEC concentration increases above 20 wt %. Our finding at open circuit potential can now initiate additive design to not only act as a sacrificial compound but also to produce a better suited SEI for the use of silicon anodes in the Li-ion vehicular industry.

Vapor Pressure and Evaporation Coefficient of Silicon Monoxide over a Mixture of Silicon and Silica

NASA Technical Reports Server (NTRS)

Ferguson, Frank T.; Nuth, Joseph A., III

2012-01-01

The evaporation coefficient and equilibrium vapor pressure of silicon monoxide over a mixture of silicon and vitreous silica have been studied over the temperature range (1433 to 1608) K. The evaporation coefficient for this temperature range was (0.007 plus or minus 0.002) and is approximately an order of magnitude lower than the evaporation coefficient over amorphous silicon monoxide powder and in general agreement with previous measurements of this quantity. The enthalpy of reaction at 298.15 K for this reaction was calculated via second and third law analyses as (355 plus or minus 25) kJ per mol and (363.6 plus or minus 4.1) kJ per mol respectively. In comparison with previous work with the evaporation of amorphous silicon monoxide powder as well as other experimental measurements of the vapor pressure of silicon monoxide gas over mixtures of silicon and silica, these systems all tend to give similar equilibrium vapor pressures when the evaporation coefficient is correctly taken into account. This provides further evidence that amorphous silicon monoxide is an intimate mixture of small domains of silicon and silica and not strictly a true compound.

Electron-beam induced damage in thin insulating films on compound semiconductors. M.S. Thesis, 1988

NASA Technical Reports Server (NTRS)

Pantic, Dragan M.

1989-01-01

Phosphorus rich plasma enhanced chemical vapor deposition (PECVD) of silicon nitride and silicon dioxide films on n-type indium phosphide (InP) substrates were exposed to electron-beam irradiation in the 5 to 40 keV range for the purpose of characterizing the damage induced in the dielectric. The electron-beam exposure was on the range of 10(exp -7) to 10(exp -3) C/sq cm. The damage to the devices was characterized by capacitance-voltage (C-V) measurements of the metal insulator semiconductor (MIS) capacitors. These results were compared to results obtained for radiation damage of thermal silicon dioxide on silicon (Si) MOS capacitors with similar exposures. The radiation induced damage in the PECVD silicon nitride films on InP was successfully annealed out in an hydrogen/nitrogen (H2/N2) ambient at 400 C for 15 min. The PECVD silicon dioxide films on InP had the least radiation damage, while the thermal silicon dioxide films on Si had the most radiation damage.

Molybdenum disilicide alloy matrix composite

DOEpatents

Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

1990-01-01

Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

Molybdenum disilicide alloy matrix composite

DOEpatents

Petrovic, John J.; Honnell, Richard E.; Gibbs, W. Scott

1991-01-01

Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

Novel drift structures for silicon and compound semiconductor X-ray and gamma-ray detectors

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

Patt, B.E.; Iwanczyk, J.S.

Recently developed silicon- and compound-semiconductor-based drift detector structures have produced excellent performance for charged particles, X-rays, and gamma rays and for low-signal visible light detection. The silicon drift detector (SDD) structures that the authors discuss relate to direct X-ray detectors and scintillation photon detectors coupled with scintillators for gamma rays. Recent designs include several novel features that ensure very low dark current and hence low noise. In addition, application of thin window technology ensures a very high quantum efficiency entrance window on the drift photodetector. The main features of the silicon drift structures for X rays and light detection aremore » very small anode capacitance independent of the overall detector size, low noise, and high throughput. To take advantage of the small detector capacitance, the first stage of the electronics needs to be integrated into the detector anode. In the gamma-ray application, factors other than electronic noise dominate, and there is no need to integrate the electronics into the anode. Thus, a different drift structure is needed in conjunction with a high-Z material. The main features in this case are large active detector volume and electron-only induced signal.« less

Production of electronic grade lunar silicon by disproportionation of silicon difluoride

NASA Technical Reports Server (NTRS)

Agosto, William N.

1993-01-01

Waldron has proposed to extract lunar silicon by sodium reduction of sodium fluorosilicate derived from reacting sodium fluoride with lunar silicon tetrafluoride. Silicon tetrafluoride is obtained by the action of hydrofluoric acid on lunar silicates. While these reactions are well understood, the resulting lunar silicon is not likely to meet electronic specifications of 5 nines purity. Dale and Margrave have shown that silicon difluoride can be obtained by the action of silicon tetrafluoride on elemental silicon at elevated temperatures (1100-1200 C) and low pressures (1-2 torr). The resulting silicon difluoride will then spontaneously disproportionate into hyperpure silicon and silicon tetrafluoride in vacuum at approximately 400 C. On its own merits, silicon difluoride polymerizes into a tough waxy solid in the temperature range from liquid nitrogen to about 100 C. It is the silicon analog of teflon. Silicon difluoride ignites in moist air but is stable under lunar surface conditions and may prove to be a valuable industrial material that is largely lunar derived for lunar surface applications. The most effective driver for lunar industrialization may be the prospects for industrial space solar power systems in orbit or on the moon that are built with lunar materials. Such systems would require large quantities of electronic grade silicon or compound semiconductors for photovoltaics and electronic controls. Since silicon is the most abundant semimetal in the silicate portion of any solar system rock (approximately 20 wt percent), lunar silicon production is bound to be an important process in such a solar power project. The lunar silicon extraction process is discussed.

Metal-Element Compounds of Titanium, Zirconium, and Hafnium as Pyrotechnic Fuels

DTIC Science & Technology

2015-05-04

including ceramic materials in this role has been far less common. Following the development of boron carbide-based pyrotechnics in our laboratories, we...ameliorate these problems. Commercially available group 4 compounds containing hydrogen, boron , carbon, nitrogen, silicon, and phosphorus were obtained for...predicted behavior suggests that these compounds may be useful for a variety of pyrotechnic applications. 1. INTRODUCTION The recent use of boron

Novel axially disubstituted non-aggregated silicon phthalocyanines.

PubMed

Bıyıklıoğlu, Zekeriya; Cakır, Dilek

2012-12-01

This paper describes the synthesis, spectroscopic characterization of a range of new axially-disubstituted silicon phthalocyanines with 2-[2-(dimethylamino)ethoxy] or 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy] groups as axial ligands. 2-[2-(Dimethylamino)ethoxy]ethanol 2, 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy]ethanol 4 are reacted with silicon phthalocyanine 1, to give an axially-disubstituted silicon phthalocyanines 3 and 5. Axially-disubstituted silicon phthalocyanine complexes were synthesized at the first time. Newly synthesized silicon phthalocyanines were characterized by UV-Vis, IR, (1)H NMR, (13)C NMR spectroscopy, ESI mass spectrometry. These new silicon(IV) phthalocyanines 3 and 5 showed excellent solubility in organic solvents such as CHCl(3), CH(2)Cl(2), acetone, DMF, DMSO, THF, EtOAc. The aggregation behavior of these compounds were investigated in different concentrations of DMSO. The effect of solvents on absorption spectra were studied in various organic solvents. The thermal stabilities of the silicon(IV) phthalocyanines 3 and 5 were determined by thermogravimetric analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

Production development of organic nonflammable spacecraft potting, encapsulating and conformal coating compounds. Volume 1: Discussion, figures, and references

NASA Technical Reports Server (NTRS)

Lieberman, S. L.

1974-01-01

Based upon extensive contacts with vendors, a broad array of non-flammable polymeric specie, and additives generally noted to have flame retarding properties, were considered. The following polymeric matrices were examined: modified silicone and fluorosilicone RTV's polyesters, epoxies, urethanes, and epoxy-urethanes. Optimization of formulations to obtain a suitable balance between the various properties and flammability resistance led to the final selection of a silicone RTV/additive-loaded compound which meets almost all program requirements. The very low valued properties found are within a realistic level of design toleration. Complete formulation, processing, and test data is provided for this compound, EPOCAST 87517-A/B, and the other formulations prepared by the project. Details of those test methods are presented along with procedures utilized in the program. In addition, a description of the special flammability facility previously designed and then modified for this program is also presented.

Elemental and compound semiconductor surface chemistry: Intelligent interfacial design facilitated through novel functionalization and deposition strategies

NASA Astrophysics Data System (ADS)

Porter, Lon Alan, Jr.

The fundamental understanding of silicon surface chemistry is an essential tool for silicon's continued dominance of the semiconductor industry in the years to come. By tapping into the vast library of organic functionalities, the synthesis of organic monolayers may be utilized to prepare interfaces, tailored to a myriad of applications ranging from silicon VLSI device optimization and MEMS to physiological implants and chemical sensors. Efforts in our lab to form stable organic monolayers on porous silicon through direct silicon-carbon linkages have resulted in several efficient functionalization methods. In the first chapter of this thesis a comprehensive review of these methods, and many others is presented. The following chapter and the appendix serve to demonstrate both potential applications and studies aimed at developing a fundamental understanding of the chemistry behind the organic functionalization of silicon surfaces. The remainder of this thesis attempts to demonstrate new methods of metal deposition onto both elemental and compound semiconductor surfaces. Currently, there is considerable interest in producing patterned metallic structures with reduced dimensions for use in technologies such as ULSI device fabrication, MEMS, and arrayed nanosensors, without sacrificing throughput or cost effectiveness. Research in our laboratory has focused on the preparation of precious metal thin films on semiconductor substrates via electroless deposition. Continuous metallic films form spontaneously under ambient conditions, in the absence of a fluoride source or an externally applied current. In order to apply this metallization method toward the development of useful technologies, patterning utilizing photolithography, microcontact printing, and scanning probe nanolithography has been demonstrated.

High-efficiency THz modulator based on phthalocyanine-compound organic films

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

He, Ting; Zhang, Bo, E-mail: bzhang@cnu.edu.cn, E-mail: sjl-phy@cnu.edu.cn; Shen, Jingling, E-mail: bzhang@cnu.edu.cn, E-mail: sjl-phy@cnu.edu.cn

2015-02-02

We report a high efficiency, broadband terahertz (THz) modulator following a study of phthalocyanine-compound organic films irradiated with an external excitation laser. Both transmission and reflection modulations of each organic/silicon bilayers were measured using THz time-domain and continuous-wave systems. For very low intensities, the experimental results show that AlClPc/Si can achieve a high modulation factor for transmission and reflection, indicating that AlClPc/Si has a superior modulation efficiency compared with the other films (CuPc and SnCl{sub 2}Pc). In contrast, the strong attenuation of the transmitted and reflected THz waves revealed that a nonlinear absorption process takes place at the organic/silicon interface.

Renal Damage Associated with Silicon Compounds in Dogs*

PubMed Central

Newberne, Paul M.; Wilson, Robert B.

1970-01-01

A number of oral preparations of various forms of silicon were fed to young adult Beagle dogs and young rats of both sexes for a period of four weeks. During the test period the animals were observed for clinical symptoms and urine and blood measurements were made. At the end of the experimental period all animals were sacrificed and subjected to a complete necropsy and histopathologic study. Polydipsia, polyuria, and soft stools in some animals fed sodium silicate and magnesium trisilicate were the only untoward clinical signs observed; all clinical tests on blood and urine were within normal limits. Gross and microscopic renal lesions were observed in dogs fed sodium silicate and magnesium trisilicate but no changes were seen in those animals fed silicon dioxide or aluminium silicate. Lesions were not observed in any of the rats. In view of the large number of commercial preparations which contain sodium silicate and magnesium trisilicate used in human medicine, these compounds deserve further study. Images PMID:5266156

Attachment chemistry of aromatic compounds on a Silicon(100) surface

NASA Astrophysics Data System (ADS)

Henriksson, Anders; Nishiori, Daiki; Maeda, Hiroaki; Miyachi, Mariko; Yamanoi, Yoshinori; Nishihara, Hiroshi

2018-03-01

A mild method was developed for the chemical attachment of aromatic compounds directly onto a hydrogen-terminated Si(100) (H-Si(100)) surface. In the presence of palladium catalyst and base, 4-iodophenylferrocene and a π-conjugated iron complex were attached to H-Si(100) electrodes and hydrogen-terminated silicon nanowires (H-SiNWs), both of which have predominant dihydride species on their surfaces. The reactions were conducted in 1,4-dioxane at 100 °C and the immobilization of both 4-ferrocenylphenyl group and π-conjugated molecular wires were confirmed and quantified by XPS and electrochemical measurements. We reported densely packed monolayer whose surface coverage (Γ), estimated from the electrochemical measurements are in analogue to similar monolayers prepared via thermal or light induced hydrosilylation reactions with alkenes or alkynes. The increase in electrochemical response observed on nanostructured silicon surfaces corresponds well to the increase in surface area, those strongly indicating that this method may be applied for the functionalization of electrodes with a variety of surface topographies.

Stir bar sorptive extraction and liquid chromatography-tandem mass spectrometry determination of polar and non-polar emerging and priority pollutants in environmental waters.

PubMed

Aparicio, Irene; Martín, Julia; Santos, Juan Luis; Malvar, José Luis; Alonso, Esteban

2017-06-02

An analytical method based on stir bar sorptive extraction (SBSE) was developed and validated for the determination of environmental concern pollutants in environmental waters by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Target compounds include six water and oil repellents (perfluorinated compounds), four preservatives (butylated hydroxytoluene and three parabens), two plasticizers (bisphenol A and di(2-ethylhexyl)phthalate), seven surfactants (four linear alkylbenzene sulfonates, nonylphenol and two nonylphenol ethoxylates), a flame retardant (hexabromocyclododecane), four hormones, fourteen pharmaceutical compounds, an UV-filter (2-ethylhexyl 4-methoxycinnamate) and nine pesticides. To achieve the simultaneous extraction of polar and non-polar pollutants two stir bar coatings were tested, the classic polydimethylsiloxane (PDMS) coating and the novel ethylene glycol modified silicone (EG-silicone). The best extraction recoveries were obtained using EG-silicone coating. The effects of sample pH, volume and ionic strength and extraction time on extraction recoveries were evaluated. The analytical method was validated for surface water and tap water samples. The method quantification limits ranged from 7.0ngL -1 to 177ngL -1 . The inter-day precision, expressed as relative standard deviation, was lower than 20%. Accuracy, expressed as relative recovery values, was in the range from 61 to 130%. The method was applied for the determination of the 48 target compounds in surface and tap water samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Development of a silicone-membrane passive sampler for monitoring cylindrospermopsin and microcystin LR-YR-RR in natural waters

NASA Astrophysics Data System (ADS)

Nyoni, Hlengilizwe; Mamba, Bhekie B.; Msagati, Titus A. M.

2017-08-01

Silicone membrane tubes were functionalised by filling them with synthesised γ-Fe2O3 nanoparticles and used as a passive sampling device for monitoring microcystins and cylindrospermopsin in aquatic environments. This novel device was calibrated for the measurement of microcystin and cylindrospermopsin concentrations in water. The effect of temperature and hydrodynamics on the sampler performance was studied in a flow-through system under controlled conditions. The chemical uptake of microcystins (MCs) and cylindrospermopsin (CYN) into the passive sampler remained linear and integrative throughout the exposure period. The rate of accumulation of most of the MC compounds tested was dependent on temperature and flow velocity. The use of 13C labelled polychlorinated biphenyls as performance reference compounds (PRCs) in silicone membrane/γ-Fe2O3 nanoparticle passive sampler, Chemcatcher and polar organic chemical integrative sampler (POCIS) was evaluated. The majority of PRCs improved the semi quantitative nature of water concentration estimated by the three samplers. The corrected sampling rate values of model biotoxin compounds were used to estimate the time-weighted average concentrations in natural cyanobacterial water blooms of the Hartbeespoort dam. The corrected sampling rates RScorr values varied from 0.1140 to 0.5628 Ld-1 between samplers with silicone membrane having the least RScorr values compared to the Chemcatcher and POCIS. The three passive sampling devises provided a more relevant picture of the biotoxin concentration in the Hartbeespoort dam. The results suggested that the three sampling devices are suitable for use in monitoring microcystins and cylindrospermopsin concentrations in aquatic environments.

Molybdenum disilicide alloy matrix composite

DOEpatents

Petrovic, J.J.; Honnell, R.E.; Gibbs, W.S.

1991-12-03

Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions are disclosed. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms. 3 figures.

Development and application of a non-targeted extraction method for the analysis of migrating compounds from plastic baby bottles by GC-MS.

PubMed

Onghena, Matthias; van Hoeck, Els; Vervliet, Philippe; Scippo, Marie Louise; Simon, Coraline; van Loco, Joris; Covaci, Adrian

2014-01-01

In 2011, the European Union prohibited the production of polycarbonate (PC) baby bottles due to the toxic effects of the PC monomer bisphenol-A. Therefore, baby bottles made of alternative materials, e.g. polypropylene (PP) or polyethersulphone (PES), are currently marketed. The principal aim of the study was the identification of major compounds migrating from baby bottles using a liquid-liquid extraction followed by GC/MS analysis. A 50% EtOH in water solution was selected as a simulant for milk. After sterilisation of the bottle, three migration experiments were performed during 2 h at 70°C. A non-targeted liquid-liquid extraction with ethyl acetate-n-hexane (1:1) was performed on the simulant samples. Identification of migrants from 24 baby bottles was done using commercially available WILEY and NIST mass spectra libraries. Differences in the migrating compounds and their intensities were observed between the different types of plastics, but also between the same polymer from a different producer. Differences in the migration patterns were perceived as well between the sterilisation and the migrations and within the different migrations. Silicone, Tritan™ and PP exhibited a wide variety of migrating compounds, whereas PES and polyamide (PA) showed a lower amount of migrants, though sometimes in relatively large concentrations (azacyclotridecan-2-one up to 250 µg kg⁻¹). Alkanes (especially in PP bottles), phthalates (dibutylphthalate in one PP bottle (±40 µg kg⁻¹) and one silicone bottle (±25 µg kg⁻¹); diisobutylphthalate in one PP (±10 µg kg⁻¹), silicone (up to ±80 µg kg⁻¹); and Tritan™ bottle (±30 µg kg⁻¹)), antioxidants (Irgafos 168, degradation products of Irganox 1010 and Irganox 1076), etc. were detected for PP, silicone and Tritan™ bottles. Although the concentrations were relatively low, some compounds not authorised by European Union Regulation No. 10/2011, such as 2,4-di-tert-butylphenol (10-100 µg kg⁻¹) or 2-butoxyethyl acetate (about 300 µg kg⁻¹) were detected. Migrating chemicals were identified as confirmed (using a standard) or as tentative (further confirmation required).

Progress in the medicinal chemistry of silicon: C/Si exchange and beyond.

PubMed

Fujii, Shinya; Hashimoto, Yuichi

2017-04-01

Application of silyl functionalities is one of the most promising strategies among various 'elements chemistry' approaches for the development of novel and distinctive drug candidates. Replacement of one or more carbon atoms of various biologically active compounds with silicon (so-called sila-substitution) has been intensively studied for decades, and is often effective for alteration of activity profile and improvement of metabolic profile. In addition to simple C/Si exchange, several novel approaches for utilizing silicon in medicinal chemistry have been suggested in recent years, focusing on the intrinsic differences between silicon and carbon. Sila-substitution offers great potential for enlarging the chemical space of medicinal chemistry, and provides many options for structural development of drug candidates.

Method of preparing high-temperature-stable thin-film resistors

DOEpatents

Raymond, L.S.

1980-11-12

A chemical vapor deposition method for manufacturing tungsten-silicide thin-film resistors of predetermined bulk resistivity and temperature coefficient of resistance (TCR) is disclosed. Gaseous compounds of tungsten and silicon are decomposed on a hot substrate to deposit a thin-film of tungsten-silicide. The TCR of the film is determined by the crystallinity of the grain structure, which is controlled by the temperature of deposition and the tungsten to silicon ratio. The bulk resistivity is determined by the tungsten to silicon ratio. Manipulation of the fabrication parameters allows for sensitive control of the properties of the resistor.

Fabrication of sinterable silicon nitride by injection molding

NASA Technical Reports Server (NTRS)

Quackenbush, C. L.; French, K.; Neil, J. T.

1982-01-01

Transformation of structural ceramics from the laboratory to production requires development of near net shape fabrication techniques which minimize finish grinding. One potential technique for producing large quantities of complex-shaped parts at a low cost, and microstructure of sintered silicon nitride fabricated by injection molding is discussed and compared to data generated from isostatically dry-pressed material. Binder selection methodology, compounding of ceramic and binder components, injection molding techniques, and problems in binder removal are discussed. Strength, oxidation resistance, and microstructure of sintered silicon nitride fabricated by injection molding is discussed and compared to data generated from isostatically dry-pressed material.

Method of preparing high-temperature-stable thin-film resistors

DOEpatents

Raymond, Leonard S.

1983-01-01

A chemical vapor deposition method for manufacturing tungsten-silicide thin-film resistors of predetermined bulk resistivity and temperature coefficient of resistance (TCR). Gaseous compounds of tungsten and silicon are decomposed on a hot substrate to deposit a thin-film of tungsten-silicide. The TCR of the film is determined by the crystallinity of the grain structure, which is controlled by the temperature of deposition and the tungsten to silicon ratio. The bulk resistivity is determined by the tungsten to silicon ratio. Manipulation of the fabrication parameters allows for sensitive control of the properties of the resistor.

Soft chemical synthesis of silicon nanosheets and their applications

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

Nakano, Hideyuki; Ikuno, Takashi

2016-12-15

Two-dimensional silicon nanomaterials are expected to show different properties from those of bulk silicon materials by virtue of surface functionalization and quantum size effects. Since facile fabrication processes of large area silicon nanosheets (SiNSs) are required for practical applications, a development of soft chemical synthesis route without using conventional vacuum processes is a challenging issue. We have recently succeeded to prepare SiNSs with sub-nanometer thicknesses by exfoliating layered silicon compounds, and they are found to be composed of crystalline single-atom-thick silicon layers. In this review, we present the synthesis and modification methods of SiNSs. These SiNSs have atomically flat andmore » smooth surfaces due to dense coverage of organic moieties, and they are easily self-assembled in a concentrated state to form a regularly stacked structure. We have also characterized the electron transport properties and the electronic structures of SiNSs. Finally, the potential applications of these SiNSs and organic modified SiNSs are also reviewed.« less

Progress in the Development of SERS-Active Substrates Based on Metal-Coated Porous Silicon

PubMed Central

Girel, Kseniya V.; Panarin, Andrei; Terekhov, Sergei N.

2018-01-01

The present work gives an overview of the developments in surface-enhanced Raman scattering (SERS) with metal-coated porous silicon used as an active substrate. We focused this review on the research referenced to SERS-active materials based on porous silicon, beginning from the patent application in 2002 and enclosing the studies of this year. Porous silicon and metal deposition technologies are discussed. Since the earliest studies, a number of fundamentally different plasmonic nanostructures including metallic dendrites, quasi-ordered arrays of metallic nanoparticles (NPs), and metallic nanovoids have been grown on porous silicon, defined by the morphology of this host material. SERS-active substrates based on porous silicon have been found to combine a high and well-reproducible signal level, storage stability, cost-effective technology and handy use. They make it possible to identify and study many compounds including biomolecules with a detection limit varying from milli- to femtomolar concentrations. The progress reviewed here demonstrates the great prospects for the extensive use of the metal-coated porous silicon for bioanalysis by SERS-spectroscopy. PMID:29883382

High-speed and on-chip graphene blackbody emitters for optical communications by remote heat transfer.

PubMed

Miyoshi, Yusuke; Fukazawa, Yusuke; Amasaka, Yuya; Reckmann, Robin; Yokoi, Tomoya; Ishida, Kazuki; Kawahara, Kenji; Ago, Hiroki; Maki, Hideyuki

2018-03-29

High-speed light emitters integrated on silicon chips can enable novel architectures for silicon-based optoelectronics, such as on-chip optical interconnects, and silicon photonics. However, conventional light sources based on compound semiconductors face major challenges for their integration with a silicon-based platform because of their difficulty of direct growth on a silicon substrate. Here we report ultra-high-speed (100-ps response time), highly integrated graphene-based on-silicon-chip blackbody emitters in the near-infrared region including telecommunication wavelength. Their emission responses are strongly affected by the graphene contact with the substrate depending on the number of graphene layers. The ultra-high-speed emission can be understood by remote quantum thermal transport via surface polar phonons of the substrates. We demonstrated real-time optical communications, integrated two-dimensional array emitters, capped emitters operable in air, and the direct coupling of optical fibers to the emitters. These emitters can open new routes to on-Si-chip, small footprint, and high-speed emitters for highly integrated optoelectronics and silicon photonics.

Progress in the Development of SERS-Active Substrates Based on Metal-Coated Porous Silicon.

PubMed

Bandarenka, Hanna V; Girel, Kseniya V; Zavatski, Sergey A; Panarin, Andrei; Terekhov, Sergei N

2018-05-21

The present work gives an overview of the developments in surface-enhanced Raman scattering (SERS) with metal-coated porous silicon used as an active substrate. We focused this review on the research referenced to SERS-active materials based on porous silicon, beginning from the patent application in 2002 and enclosing the studies of this year. Porous silicon and metal deposition technologies are discussed. Since the earliest studies, a number of fundamentally different plasmonic nanostructures including metallic dendrites, quasi-ordered arrays of metallic nanoparticles (NPs), and metallic nanovoids have been grown on porous silicon, defined by the morphology of this host material. SERS-active substrates based on porous silicon have been found to combine a high and well-reproducible signal level, storage stability, cost-effective technology and handy use. They make it possible to identify and study many compounds including biomolecules with a detection limit varying from milli- to femtomolar concentrations. The progress reviewed here demonstrates the great prospects for the extensive use of the metal-coated porous silicon for bioanalysis by SERS-spectroscopy.

Method of high purity silane preparation

DOEpatents

Tsuo, Y. Simon; Belov, Eugene P.; Gerlivanov, Vadim G.; Zadde, Vitali V.; Kleschevnikova, Solomonida I.; Korneev, Nikolai N.; Lebedev, Eugene N.; Pinov, Akhsarbek B.; Ryabenko, Eugene A.; Strebkov, Dmitry S.; Chernyshev, Eugene A.

2000-01-01

A process for the preparation of high purity silane, suitable for forming thin layer silicon structures in various semiconductor devices and high purity poly- and single crystal silicon for a variety of applications, is provided. Synthesis of high-purity silane starts with a temperature assisted reaction of metallurgical silicon with alcohol in the presence of a catalyst. Alcoxysilanes formed in the silicon-alcohol reaction are separated from other products and purified. Simultaneous reduction and oxidation of alcoxysilanes produces gaseous silane and liquid secondary products, including, active part of a catalyst, tetra-alcoxysilanes, and impurity compounds having silicon-hydrogen bonds. Silane is purified by an impurity adsorption technique. Unreacted alcohol is extracted and returned to the reaction with silicon. Concentrated mixture of alcoxysilanes undergoes simultaneous oxidation and reduction in the presence of a catalyst at the temperature -20.degree. C. to +40.degree. C. during 1 to 50 hours. Tetra-alcoxysilane extracted from liquid products of simultaneous oxidation and reduction reaction is directed to a complete hydrolysis. Complete hydrolysis of tetra-alcoxysilane results in formation of industrial silica sol and alcohol. Alcohol is dehydrated by tetra-alcoxysilane and returned to the reaction with silicon.

Chemical and Sensory Evaluation of Silicone and Polylactic Acid-Based Remedial Treatments for Elevated Methoxypyrazine Levels in Wine.

PubMed

Botezatu, Andreea; Kemp, Belinda S; Pickering, Gary J

2016-09-16

Alkylmethoxypyrazines (MPs) are a class of compounds that can elicit undesirable aroma and flavor characteristics in wine, and resist remediation using traditional wine making approaches. MPs are grape-derived constituents as well as contaminants from Coccinellidae beetles present during wine processing; the latter eliciting an off-flavor referred to as 'ladybug taint'. In this study we investigated the capacity of two plastic polymers-one silicone-based, the other polylactic acid-based-applied with varying surface areas to reduce concentrations of isopropylmethoxypyrazine (IPMP), sec-butylmethoxypyrazine (SBMP) and isobutylmethoxypyrazine (IBMP) in a Merlot wine using multi-dimensional gas chromatography coupled with mass spectrometry and headspace solid phase microextraction (SPME-MDGCMS). The impact of treatments on the sensory characteristics of the wine (descriptive analysis) and volatile aroma compounds (VOCs) (SPME-MDGCMS) was also investigated. Results showed substantial reductions for all of the target odorants: up to 38%, 44% and 39% for IPMP, SBMP and IBMP, respectively, for the silicone polymer, and up to 75%, 78% and 77% for IPMP, SBMP and IBMP, respectively, for the polylactic acid polymer. These polymers had no or minimal effect on VOCs at applications of 200 cm²/L for silicone or for all polylactic acid treatments. Sensory impacts were less clear, but generally showed minimal effect from the treatments. Taken overall, the data confirm the utility of both polylactic acid and silicone polymers in reducing elevated levels of grape-derived MPs, as well as potentially improving wine contaminated by ladybug taint.

Adhesion of Silicone Elastomer Seals for NASA's Crew Exploration Vehicle

NASA Technical Reports Server (NTRS)

deGroh, Henry C., III; Miller, Sharon K. R.; Smith, Ian M.; Daniels, Christopher C.; Steinetz, Bruce M

2008-01-01

Silicone rubber seals are being considered for a number of interfaces on NASA's Crew Exploration Vehicle (CEV). Some of these joints include the docking system, hatches, and heat shield-to-back shell interface. A large diameter molded silicone seal is being developed for the Low Impact Docking System (LIDS) that forms an effective seal between the CEV and International Space Station (ISS) and other future Constellation Program spacecraft. Seals between the heat shield and back shell prevent high temperature reentry gases from leaking into the interface. Silicone rubber seals being considered for these locations have inherent adhesive tendencies that would result in excessive forces required to separate the joints if left unchecked. This paper summarizes adhesion assessments for both as-received and adhesion-mitigated seals for the docking system and the heat shield interface location. Three silicone elastomers were examined: Parker Hannifin S0899-50 and S0383-70 compounds, and Esterline ELA-SA-401 compound. For the docking system application various levels of exposure to atomic oxygen (AO) were evaluated. Moderate AO treatments did not lower the adhesive properties of S0899-50 sufficiently. However, AO pretreatments of approximately 10(exp 20) atoms/sq cm did lower the adhesion of S0383-70 and ELA-SA-401 to acceptable levels. For the heat shield-to-back shell interface application, a fabric covering was also considered. Molding Nomex fabric into the heat shield pressure seal appreciably reduced seal adhesion for the heat shield-to-back shell interface application.

Analysis of periprosthetic capsular tissue from women with silicone breast implants by magic-angle spinning NMR.

PubMed

Garrido, L; Young, V L

1999-09-01

The amount of silicone (polydimethylsiloxane [PDMS]) in capsular tissue surgically removed from women with breast implants was measured by using (29)Si and (1)H magic-angle spinning solid-state NMR spectroscopy. Twelve women having smooth surface silicone gel-filled implants, including a subject with "low-bleed" double-lumen implants, had detectable levels of PDMS ranging from 0. 05 to 9.8% silicon in wet tissue (w/w). No silicon-containing compounds other than PDMS were detected. No correlation was found between the amount of PDMS measured in the capsular tissue and the length of implantation time (Pearson correlation coefficient, r = 0. 22). The results showed no relationship between higher amounts of PDMS and capsular contracture (p = 0.74) or other symptoms (p = 0. 53). Magn Reson Med 42:436-441, 1999. Copyright 1999 Wiley-Liss, Inc.

Pulsed energy synthesis and doping of silicon carbide

DOEpatents

Truher, J.B.; Kaschmitter, J.L.; Thompson, J.B.; Sigmon, T.W.

1995-06-20

A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate is disclosed, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27--730 C is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including HETEROJUNCTION-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

Pulsed energy synthesis and doping of silicon carbide

DOEpatents

Truher, Joel B.; Kaschmitter, James L.; Thompson, Jesse B.; Sigmon, Thomas W.

1995-01-01

A method for producing beta silicon carbide thin films by co-depositing thin films of amorphous silicon and carbon onto a substrate, whereafter the films are irradiated by exposure to a pulsed energy source (e.g. excimer laser) to cause formation of the beta-SiC compound. Doped beta-SiC may be produced by introducing dopant gases during irradiation. Single layers up to a thickness of 0.5-1 micron have been produced, with thicker layers being produced by multiple processing steps. Since the electron transport properties of beta silicon carbide over a wide temperature range of 27.degree.-730.degree. C. is better than these properties of alpha silicon carbide, they have wide application, such as in high temperature semiconductors, including hetero-junction bipolar transistors and power devices, as well as in high bandgap solar arrays, ultra-hard coatings, light emitting diodes, sensors, etc.

Novel coatings for stir bar sorptive extraction to determine pharmaceuticals and personal care products in environmental waters by liquid chromatography and tandem mass spectrometry.

PubMed

Gilart, Núria; Miralles, Núria; Marcé, Rosa Maria; Borrull, Francesc; Fontanals, Núria

2013-04-24

Two new commercially available polar coatings for stir bar sorptive extraction (SBSE), consisting of polyacrylate (PA) with a proportion of polyethyleneglycol (PEG) (Acrylate Twister(®)) and PEG modified silicone (EG Silicone Twister(®)), were evaluated and compared with the classic coating based on polydimethylsiloxane (PDMS Twister(®)) for the extraction of a group of pharmaceuticals and personal care products (PPCPs) from wastewater samples. The SBSE parameters, such as sample pH, agitation speed, extraction temperature, extraction time, desorption solvent and time, were optimised in order to achieve suitable sorption of the target analytes. The EG Silicone coating enabled more efficient extraction of some polar compounds as well as improving the sorption of apolar compounds, in comparison with the other two coatings. Finally, the method of SBSE followed by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) using the EG Silicone coating was validated achieving good linearity (r(2)>0.994, except for CBZ (r(2)>0.989)), precision (%RSD<17%) and low limits of quantification (LOQs) (20-40 ng L(-1)). The SBSE/LC-MS/MS methodology was applied for the determination of PPCPs in wastewater samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Organic filler from golden apple snails shells to improve the silicone rubber insulator properties

NASA Astrophysics Data System (ADS)

Tepsila, Sujirat; Suksri, Amnart

2018-02-01

This paper investigates the effect of an addition of filler compound using golden apple snail shell as an organic filler to the silicone rubber insulator. The filler obtained from golden apple snail shell is found mostly contained calcium carbonate. The organic calcium carbonate (CaCO3) with particle size of 45, 75, 100 and 300 micron were prepared. Sample of silicone rubber that were filled with fillers were tested under ASTM D638-02a type standard for mechanical test. Also, electrical test such as I-V characteristics (ASTM D257-07) and dry arc test according to ASTM D495-14 have been performed. The results revealed that using larger particle size of organic filler obtained from the golden apple snail shell resulted to higher value of dielectric constant as well as higher dielectric strength. Also, the filler helps slow down the tracking activity at an insulator surface due to its crystals of calcium carbonate. However, when using excessive amount of filler, the sample will have a drawbacks in mechanical properties. By using agriculture waste as a filler compound, one can reduced the usage of commercial CaCO3 as an inorganic materials and to lower the investment cost to a final silicone rubber product.

Method of dehydroxylating a hydroxylated material and method of making a mesoporous film

DOEpatents

Domansky, Karel [Richland, WA; Fryxell, Glen E [Kennewick, WA; Liu, Jun [West Richland, WA; Kohler, Nathan J [Richland, WA; Baskaran, Suresh [Kennewick, WA

2002-05-07

The present invention is a method of dehydroxylating a silica surface that is hydroxylated having the steps of exposing the silica surface separately to a silicon organic compound and a dehydroxylating gas. Exposure to the silicon organic compound can be in liquid, gas or solution phase, and exposure to a dehydroxylating gas is typically at elevated temperatures. In one embodiment, the improvement of the dehydroxylation procedure is the repetition of the soaking and dehydroxylating gas exposure. In another embodiment, the improvement is the use of an inert gas that is substantially free of hydrogen. In yet another embodiment, the present invention is the combination of the two-step dehydroxylation method with a surfactant templating method of making a mesoporous film.

Tailored Organometallic Polymers

DTIC Science & Technology

1993-01-31

2-4). These synthetic pathways provide access to a wide variety of new silicon compounds for use as reagents in organic syntheses and the electronics...34Si0 2 as a Source of Si Containing Compounds / Polymers", D.J. Ray, R.M. Laine, C. Viney and T.R. Robinson, ACS Polymer Preprints (1991) 32(3), 550...3) as precursors to orgar.osilicon compounds .[10-12] Pentacoordinate silicates are easily prepa’ed frotv tetrasubstituted Si centers containing

Monolayer Contact Doping of Silicon Surfaces and Nanowires Using Organophosphorus Compounds

PubMed Central

Hazut, Ori; Agarwala, Arunava; Subramani, Thangavel; Waichman, Sharon; Yerushalmi, Roie

2013-01-01

Monolayer Contact Doping (MLCD) is a simple method for doping of surfaces and nanostructures1. MLCD results in the formation of highly controlled, ultra shallow and sharp doping profiles at the nanometer scale. In MLCD process the dopant source is a monolayer containing dopant atoms. In this article a detailed procedure for surface doping of silicon substrate as well as silicon nanowires is demonstrated. Phosphorus dopant source was formed using tetraethyl methylenediphosphonate monolayer on a silicon substrate. This monolayer containing substrate was brought to contact with a pristine intrinsic silicon target substrate and annealed while in contact. Sheet resistance of the target substrate was measured using 4 point probe. Intrinsic silicon nanowires were synthesized by chemical vapor deposition (CVD) process using a vapor-liquid-solid (VLS) mechanism; gold nanoparticles were used as catalyst for nanowire growth. The nanowires were suspended in ethanol by mild sonication. This suspension was used to dropcast the nanowires on silicon substrate with a silicon nitride dielectric top layer. These nanowires were doped with phosphorus in similar manner as used for the intrinsic silicon wafer. Standard photolithography process was used to fabricate metal electrodes for the formation of nanowire based field effect transistor (NW-FET). The electrical properties of a representative nanowire device were measured by a semiconductor device analyzer and a probe station. PMID:24326774

Economic analysis of crystal growth in space

NASA Technical Reports Server (NTRS)

Ulrich, D. R.; Chung, A. M.; Yan, C. S.; Mccreight, L. R.

1972-01-01

Many advanced electronic technologies and devices for the 1980's are based on sophisticated compound single crystals, i.e. ceramic oxides and compound semiconductors. Space processing of these electronic crystals with maximum perfection, purity, and size is suggested. No ecomonic or technical justification was found for the growth of silicon single crystals for solid state electronic devices in space.

Low temperature solution synthesis of silicon, germanium and Si-Ge axial heterostructures in nanorod and nanowire form.

PubMed

Flynn, G; Stokes, K; Ryan, K M

2018-05-31

Herein, we report the formation of silicon, germanium and more complex Si-SixGe1-x and Si-Ge axial 1D heterostructures, at low temperatures in solution. These nanorods/nanowires are grown using phenylated compounds of silicon and germanium as reagents, with precursor decomposition achieved at substantially reduced temperatures (200 °C for single crystal nanostructures and 300 °C for heterostructures), through the addition of a reducing agent. This low energy route for the production of these functional nanostructures as a wet chemical in high yield is attractive to meet the processing needs for next generation photovoltaics, batteries and electronics.

Liquid phase sintering of silicon carbide

DOEpatents

Cutler, R.A.; Virkar, A.V.; Hurford, A.C.

1989-05-09

Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1,600 C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase. 4 figs.

Liquid phase sintering of silicon carbide

DOEpatents

Cutler, Raymond A.; Virkar, Anil V.; Hurford, Andrew C.

1989-01-01

Liquid phase sintering is used to densify silicon carbide based ceramics using a compound comprising a rare earth oxide and aluminum oxide to form liquids at temperatures in excess of 1600.degree. C. The resulting sintered ceramic body has a density greater than 95% of its theoretical density and hardness in excess of 23 GPa. Boron and carbon are not needed to promote densification and silicon carbide powder with an average particle size of greater than one micron can be densified via the liquid phase process. The sintered ceramic bodies made by the present invention are fine grained and have secondary phases resulting from the liquid phase.

New Approaches to the Synthesis of Novel Organosilanes.

DTIC Science & Technology

1983-10-01

through" electrode composed of RVC ( reticulated vitreous carbon ), a highly conductive sponge of carbonized material. Both of these flow systems...effective in promoting silicon- carbon bond cleavage and reformation to give cyclic and cage compounds readily and in good yields: (tA*3-9)(CŖ). n 2-S...silicon to carbon bonds and has broad based applications in research and industrial labs. The increase in reaction rate and yield with ultrasonic waves

Synthesis and characterization of SiC based composite materials for immobilizing radioactive graphite

NASA Astrophysics Data System (ADS)

Wang, Qing; Teng, Yuancheng; Wu, Lang; Zhang, Kuibao; Zhao, Xiaofeng; Hu, Zhuang

2018-06-01

In order to immobilize high-level radioactive graphite, silicon carbide based composite materials{ (1-x) SiC· x MgAl2O4 (0.1 ≤ x≤0.4) } were fabricated by solid-state reaction at 1370 °C for 2 h in vacuum. Residual graphite and precipitated corundum were observed in the as-synthesized product, which attributed to the interface reaction of element silicon and magnesium compounds. To further understand the reasons for the presence of graphite and corundum, the effects of mole ratio of Si/C, MgAl2O4 content and non-stoichiometry of MgAl2O4 on the synthesis were investigated. To immobilize graphite better, residual graphite should be eliminated. The target product was obtained when the mole ratio of Si/C was 1.3:1, MgAl2O4 content was x = 0.2, and the mole ratio of Al to Mg in non-stoichiometric MgAl2O4 was 1.7:1. In addition, the interface reaction between magnesium compounds and silicon not graphite was displayed by conducting a series of comparative experiments. The key factor for the occurrence of interface reaction is that oxygen atom is transferred from magnesium compound to SiO gas. Infrared and Raman spectrum revealed the increased disorders of graphite after being synthesized.

Silicone rubber selection for passive sampling of pesticides in water.

PubMed

Martin, A; Margoum, C; Randon, J; Coquery, M

2016-11-01

Silicone rubber can extract organic compounds with a broad range of polarities (logKow>2-3) from aqueous samples. Such compounds include substances of major concern in the protection of aquatic ecosystems and human health, e.g. pesticides. Silicone rubbers (SRs) with various characteristics have been successfully used in sorptive methods for water sample extraction in the laboratory (SPME, SBSE), and for passive sampling in aquatic environments. However, only few studies have evaluated variability in organic compound sorption due to the origin of SRs, particularly for pesticides. The aim of this study was to select an SR for the extraction of pesticides from water samples by passive sampling. To this end we measured the impact of seven SR formulations on sorption capacity, defined by the partition coefficient (Ksw). Kinetic experiments and sorption isotherms were performed to determine extraction recovery as a selection criterion for SRs, and pesticide partition coefficients. Very large differences in affinity for pesticides were found between two kinds of SRs: "Polymerized SR kits" and "Manufactured SRs". One SR was chosen among the "Manufactured SRs", and the Ksw values of 21 pesticides were determined, filling a gap in the literature (1.50

Interpenetrated Uranyl-Organic Frameworks with bor and pts Topology: Structure, Spectroscopy, and Computation.

PubMed

Liu, Chao; Chen, Fang-Yuan; Tian, Hong-Rui; Ai, Jing; Yang, Weiting; Pan, Qing-Jiang; Sun, Zhong-Ming

2017-11-20

Two novel three-dimensional interpenetrated uranyl-organic frameworks, (NH 4 ) 4 [(UO 2 ) 4 (L 1 ) 3 ]·6H 2 O (1) and [(UO 2 ) 2 (H 2 O) 2 L 2 ]·2H 2 O (2), where L 1 = tetrakis(3-carboxyphenyl)silicon and L 2 = tetrakis(4-carboxyphenyl)silicon, were synthesized by a combination of two isomeric tetrahedral silicon-centered ligands with 3-connected triangular [(UO 2 )(COO) 3 ] - and 4-connected dinuclear [(UO 2 ) 2 (COO) 4 ] units, respectively. Structural analyses indicate that 1 possesses a 2-fold interpenetrating anion bor network, while 2 exhibits a 3-fold interpenetrated 4,4-connected neutral network with pts topology. Both compounds were characterized by thermogravimetric analysis and IR, UV-vis, and photoluminescence spectroscopy. A relativistic density functional theory (DFT) investigation on 10 model compounds of 1 and 2 shows good agreement of the structural parameters, stretching vibrational frequencies, and absorption with experimental results; the time-dependent DFT calculations unravel that low-energy absorption bands originate from ligand-to-uranium charge transfer.

Long-Term Stability of Mold Compounds and the Influence on Semiconductor Device Reliability

NASA Astrophysics Data System (ADS)

Mahler, Joachim; Mengel, Manfred

2012-07-01

Lifetimes of semiconductor devices are specified according to the products and their applications to ensure safe operation, for instance as part of an automobile product. The long-term stability of the device is strongly dependent on the chip encapsulation and its adhesion to the chip and substrate. Molded silicon strips that act as a model system for molded chips inside semiconductor devices were investigated. Four commercially available mold compounds were applied on silicon strips and stored over 5 years at room temperature (RT), and changes in the thermomechanical behavior were analyzed. After storage, all molded strips exhibited warpage reduction in the range of 11% to 14% at RT with respect to the initial warpage. The temperatures for the stress-free state also changed during storage and were located between 228°C and 235°C for each mold. Additional stress applied to the stored modules, by temperature cycling as well as high-temperature storage, increased the warpage of the molded silicon samples. For further interpretation of measured results, finite-element method calculations were performed.

Questing and the application for silicon based ternary compound within ultra-thin layer of SIS intermediate region

NASA Astrophysics Data System (ADS)

Chen, Shumin; Gao, Ming; Wan, Yazhou; Du, Huiwei; Li, Yong; Ma, Zhongquan

2016-12-01

A silicon based ternary compound was supposed to be solid synthesized with In, Si and O elements by magnetron sputtering of indium tin oxide target (ITO) onto crystal silicon substrate at 250 °C. To make clear the configuration of the intermediate region, a potential method to obtain the chemical bonding of Si with other existing elements was exploited by X-ray photoelectron spectroscopy (XPS) instrument combined with other assisted techniques. The phase composition and solid structure of the interfacial region between ITO and Si substrate were investigated by X-ray diffraction (XRD) and high resolution cross sectional transmission electron microscope (HR-TEM). A photovoltaic device with structure of Al/Ag/ITO/SiOx/p-Si/Al was assembled by depositing ITO films onto the p-Si substrate by using magnetron sputtering. The new matter has been assumed to be a buffer layer for semiconductor-insulator-semiconductor (SIS) photovoltaic device and plays critical role for the promotion of optoelectronic conversion performance from the view point of device physics.

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

Sanders, R.S.

The effects of heat strip time, heat strip temperature, catalyst ratio, mold cure time, post cure time, and post cure temperature on a hybrid (UCC/SE-54/497XL) cellular silicone molding compound are reported.

Method for making organooxysilanes

DOEpatents

Schattenmann, Florian Johannes

2003-12-23

A method for the preparation of organooxysilanes containing at least one silicon-carbon bond is provided which comprises reacting at least one tetraorganooxysilane with at least one transition metal organo compound.

The integration of InGaP LEDs with CMOS on 200 mm silicon wafers

NASA Astrophysics Data System (ADS)

Wang, Bing; Lee, Kwang Hong; Wang, Cong; Wang, Yue; Made, Riko I.; Sasangka, Wardhana Aji; Nguyen, Viet Cuong; Lee, Kenneth Eng Kian; Tan, Chuan Seng; Yoon, Soon Fatt; Fitzgerald, Eugene A.; Michel, Jurgen

2017-02-01

The integration of photonics and electronics on a converged silicon CMOS platform is a long pursuit goal for both academe and industry. We have been developing technologies that can integrate III-V compound semiconductors and CMOS circuits on 200 mm silicon wafers. As an example we present our work on the integration of InGaP light-emitting diodes (LEDs) with CMOS. The InGaP LEDs were epitaxially grown on high-quality GaAs and Ge buffers on 200 mm (100) silicon wafers in a MOCVD reactor. Strain engineering was applied to control the wafer bow that is induced by the mismatch of coefficients of thermal expansion between III-V films and silicon substrate. Wafer bonding was used to transfer the foundry-made silicon CMOS wafers to the InGaP LED wafers. Process trenches were opened on the CMOS layer to expose the underneath III-V device layers for LED processing. We show the issues encountered in the 200 mm processing and the methods we have been developing to overcome the problems.

Single Stage Silicone Border Molded Closed Mouth Impression Technique-Part II.

PubMed

Solomon, E G R

2011-09-01

Functioning of a complete denture depends to a great extent on the impression technique. Several impression techniques have been described in the literature since the turn of this century when Greene [Clinical courses in dental prothesis, 1916] brothers introduced the first scientific system of recording dental impression. Advocates of each technique have their own claim of superiority over the other. The introduction of elastomeric impression materials [Skinner and Cooper, J Am Dent Assoc 51:523-536, 1955] has made possible new techniques of recording impression for complete denture construction. These rubber like materials are of two types; one has a polysulfide base and is popularily known as polysulfide rubber (Thiokol and Mercaptan). The other variety has a silicone base known as silicone rubber or silicone elastomer. Silicone elastomers are available in four different consistencies; a thin easy flowing light bodied material,a creamy medium bodied material, a highly viscous heavy bodied material and a kneadable putty material. This paper describes an active closed mouth impression technique with one stage border molding using putty silicone material as a substitute for low fusing compound.

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

NASA Technical Reports Server (NTRS)

Stanley, Stephanie D.

2008-01-01

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system, Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various meta! (steel, inconel, and aluminum), phenolic (carbon cloth phenolic and glass cloth phenolic), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber, silica-filled ethylene propylenediene monomer, and carbon-filled ethylene propylenediene monomer) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

Microstructure of SiC-Si-Al2O3 composites derived from silicone resin - metal aluminum filler compounds by low temperature reduction process

NASA Astrophysics Data System (ADS)

Narisawa, M.; Abe, Y.

2011-06-01

Concentrated slurry of a silicone resin with low carbon content, 3 μm aluminum particles and ethanol were prepared. After casting, addition of cross-linking agent and drying, silicone resin-aluminum composite with thick sheet form was obtained. The prepared sheet was heat-treated at 933 or 1073K with various holding times to characterize formed phases during the heat treatments. XRD patterns and FT-IR spectra revealed free Si formation and existence of Si-O-Si bond at 933K. The Si-O-Si bond, however, disappeared and silicon carbide was formed at 1073K. SEM observation indicated formation of cracks bridged with a number of tiny struts at 933K and conversion to wholly porous structure at 1073K.

Evolution of Non-metallic Inclusions and Precipitates in Oriented Silicon Steel

NASA Astrophysics Data System (ADS)

Luo, Yan; Yang, Wen; Ren, Qiang; Hu, Zhiyuan; Li, Ming; Zhang, Lifeng

2018-06-01

The evolution of inclusions in oriented silicon steel during the manufacturing process was carried out by chemical composition analysis, non-aqueous electrolytic corrosion, and thermodynamic calculation. The morphology, composition, and size of inclusions were analyzed introducing field emission scanning electron microscope. The oxides were mainly formed during the secondary refining, and the nitrides, sulfides, and compounds were formed during the solidification and cooling of steel in the processes of continuous casting and hot rolling.

Environmental Effects in Niobium Base Alloys and Other Selected Intermetallic Compounds

DTIC Science & Technology

1991-04-30

formation of this surface layer requires that the oxide be more stable than the lowest oxide of the base metal. Figure 2 indicates the free energies of...such requirements for temperatures beyond 10500C are aluminum and silicon. Both of these elements form oxides with large, negative free energies of...Nb-Si, and Ta-Si systems. In attempting to develop alloys in which aluminum or silicon is selectively oxidized, the standard free energies of oxides

Surface segregation on Fe3%Si0.04%VC(100) single crystal surfaces

NASA Astrophysics Data System (ADS)

Uebing, C.; Viefhaus, H.

1990-10-01

Surface segregation phenomena on (100) oriented single crystal surfaces of the ferritic Fe-3%Si-0.04%V-C alloy were investigated by AES and LEED. At temperatures below 635 °C vanadium and carbon cosegregation is observed after prolonged heating. At thermodynamic equilibrium the substrate surface is saturated with the binary surface compound VC. The two-dimensional VC is epitaxially arranged on the substrate surface as indicated by LEED investigations. Its structure corresponds to the (100) plane of the three-dimensional VC with rocksalt structure. Sharp above 635 °C the surface compound VC is dissolved into the bulk. At higher temperatures the substrate surface is covered with segregated silicon forming a c(2 × 2) structure. This surface phase transition is reversible. Because of the low concentration and slow diffusion of vanadium, non-equilibrium surface states are formed as intermediates upon segregation of silicon and carbon. Below 500 °C a disordered graphite layer with a characteristical asymmetrical C Auger peak is observed on the substrate surface. Above 500 °C carbon segregation leads to the formation of an ordered c(2 × 2) structure with a symmetrical C Auger peak being characteristic for carbidic or atomically adsorbed species. At increasing temperatures silicon segregation takes place leading to a c(2 × 2) structure. Between silicon and carbon site competition is effective.

Core-based intrinsic fiber-optic absorption sensor for the detection of volatile organic compounds

NASA Astrophysics Data System (ADS)

Klunder, Gregory L.; Russo, Richard E.

1995-03-01

A core-based intrinsic fiber-optic absorption sensor has been developed and tested for the detection of volatile organic compounds. The distal ends of transmitting and receiving fibers are connected by a small cylindrical section of an optically clear silicone rubber. The silicone rubber acts both as a light pipe and as a selective membrane into which the analyte molecules can diffuse. The sensor has been used to detect volatile organics (trichloroethylene, 1,1-dichloroethylene, and benzene) in both aqueous solutions and in the vapor phase or headspace. Absorption spectra obtained in the near-infrared (near-IR) provide qualitative and quantitative information about the analyte. Water, which has strong broad-band absorption in the near-IR, is excluded from the spectra because of the hydrophobic properties of the silicone rubber. The rate-limiting step is shown to be the diffusion through the Nernstian boundary layer surrounding the sensor and not the diffusion through the silicone polymer. The rate of analyte diffusion into the sensor, as measured by the t(sub 90) values (the time required for the sensor to reach 90% of the equilibrium value), is 30 min for measurements in aqueous solutions and approximately 3 min for measurements made in the headspace. The limit of detection obtained with this sensor is approximately 1.1 ppm for trichloroethylene in an aqueous solution.

Silicon influence on resistance induction against Bemisia tabaci biotype B (Genn.) (Hemiptera: Aleyrodidae) and on vegetative development in two soybean cultivars.

PubMed

Ferreira, R S; Moraes, J C; Antunes, C S

2011-01-01

The potential of populations of Bemisia tabaci (Genn.) to become resistant to insecticides has stimulated research into alternative tactics of integrated pest management such as the induction of host-plant resistance. Recent data have shown that silicon can increase the degree of resistance of host plants to insect pests. Therefore the aim of our work was to study the effects of silicon application on the vegetative development of soybean plants and on the induction of resistance to the silverleaf whitefly, B. tabaci biotype B. We performed choice and no-choice tests of oviposition preference on two soybean cultivars, IAC-19 (moderately resistant to B. tabaci biotype B) and MONSOY-8001 (susceptible), with and without application of silicon. Silicon did not affect silverleaf whitefly oviposition preferences, but caused significant mortality in nymphs. Thus, silicon increased the degree of resistance to silverleaf whitefly. Silicon decreased the production of phenolic compounds, but did not affect lignin production. However, when applied to cultivar IAC-19, it increased the production of non-protein organic nitrogen. Silicon had no effect on the vegetative development of soybean plants, but it increased the degree of resistance to the silverleaf whitefly. We conclude that silicon applications combined with cultivar IAC-19 can significantly decrease silverleaf whitefly populations, having a positive impact both on the soybean plant and on the environment.

Improvements in pollutant monitoring: optimizing silicone for co-deployment with polyethylene passive sampling devices.

PubMed

O'Connell, Steven G; McCartney, Melissa A; Paulik, L Blair; Allan, Sarah E; Tidwell, Lane G; Wilson, Glenn; Anderson, Kim A

2014-10-01

Sequestering semi-polar compounds can be difficult with low-density polyethylene (LDPE), but those pollutants may be more efficiently absorbed using silicone. In this work, optimized methods for cleaning, infusing reference standards, and polymer extraction are reported along with field comparisons of several silicone materials for polycyclic aromatic hydrocarbons (PAHs) and pesticides. In a final field demonstration, the most optimal silicone material is coupled with LDPE in a large-scale study to examine PAHs in addition to oxygenated-PAHs (OPAHs) at a Superfund site. OPAHs exemplify a sensitive range of chemical properties to compare polymers (log Kow 0.2-5.3), and transformation products of commonly studied parent PAHs. On average, while polymer concentrations differed nearly 7-fold, water-calculated values were more similar (about 3.5-fold or less) for both PAHs (17) and OPAHs (7). Individual water concentrations of OPAHs differed dramatically between silicone and LDPE, highlighting the advantages of choosing appropriate polymers and optimized methods for pollutant monitoring. Copyright © 2014 Elsevier Ltd. All rights reserved.

IMPROVEMENTS IN POLLUTANT MONITORING: OPTIMIZING SILICONE FOR CO-DEPLOYMENT WITH POLYETHYLENE PASSIVE SAMPLING DEVICES

PubMed Central

O’Connell, Steven G.; McCartney, Melissa A.; Paulik, L. Blair; Allan, Sarah E.; Tidwell, Lane G.; Wilson, Glenn; Anderson, Kim A.

2014-01-01

Sequestering semi-polar compounds can be difficult with low-density polyethylene (LDPE), but those pollutants may be more efficiently absorbed using silicone. In this work, optimized methods for cleaning, infusing reference standards, and polymer extraction are reported along with field comparisons of several silicone materials for polycyclic aromatic hydrocarbons (PAHs) and pesticides. In a final field demonstration, the most optimal silicone material is coupled with LDPE in a large-scale study to examine PAHs in addition to oxygenated-PAHs (OPAHs) at a Superfund site. OPAHs exemplify a sensitive range of chemical properties to compare polymers (log Kow 0.2–5.3), and transformation products of commonly studied parent PAHs. On average, while polymer concentrations differed nearly 7-fold, water-calculated values were more similar (about 3.5-fold or less) for both PAHs (17) and OPAHs (7). Individual water concentrations of OPAHs differed dramatically between silicone and LDPE, highlighting the advantages of choosing appropriate polymers and optimized methods for pollutant monitoring. PMID:25009960

Atomic Scale Understanding of Poly-Si/SiO2/c-Si Passivated Contacts: Passivation Degradation Due to Metallization

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

Aguiar, Jeffery A.; Young, David; Lee, Benjamin

2016-11-21

The key attributes for achieving high efficiency crystalline silicon solar cells include class leading developments in the ability to approach the theoretical limits of silicon solar technology (29.4% efficiency). The push for high efficiency devices is further compounded with the clear need for passivation to reduce recombination at the metal contacts. At the same time there is stringent requirement to retain the same material device quality, surface passivation, and performance characteristics following subsequent processing. The development of passivated silicon cell structures that retain active front and rear surface passivation and overall material cell quality is therefore a relevant and activemore » area of development. To address the potential outcomes of metallization on passivated silicon stack, we report on some common microstructural features of degradation due to metallization for a series of silicon device stacks. A fundamental materials understanding of the metallization process on retaining high-efficiency passivated Si devices is therefore gained over these series of results.« less

Effect of organo-clay on the dielectric relaxation response of silicone rubber

NASA Astrophysics Data System (ADS)

Gharavi, N.; Razzaghi-Kashani, M.; Golshan-Ebrahimi, N.

2010-02-01

Dielectric elastomers are light weight, low-cost, highly deformable and fast response smart materials capable of converting electrical energy into mechanical work or vice versa. Silicone rubber is a well-known dielectric elastomer which is used as actuator, and in order to enhance the efficiency of this smart material, compounding of silicone rubber with various fillers can be carried out. The effect of organically modified montmorillonite (OMMT) nano-clay on improvement of dielectric properties, actuation stress and its relaxation response was considered in this study. OMMT was dispersed in room temperature vulcanized (RTV) silicone rubber, and a composite film was cast. Using an in-house actuation set-up, it was shown that the actuation stress for a given electric field intensity is higher for composites than that for pristine silicone rubber. Also, the time-dependent actuation response of the samples was evaluated, and it was shown that the characteristic relaxation time of the actuation stress for composites is less than for the pristine rubber as a result of OMMT addition.

Chemical vapor deposition of silicon, silicon dioxide, titanium and ferroelectric thin films

NASA Astrophysics Data System (ADS)

Chen, Feng

Various silicon-based thin films (such as epitaxial, polycrystalline and amorphous silicon thin films, silicon dioxide thin films and silicon nitride thin films), titanium thin film and various ferroelectric thin films (such as BaTiO3 and PbTiO3 thin films) play critical roles in the manufacture of microelectronics circuits. For the past few years, there have been tremendous interests to search for cheap, safe and easy-to-use methods to develop those thin films with high quality and good step coverage. Silane is a critical chemical reagent widely used to deposit silicon-based thin films. Despite its wide use, silane is a dangerous material. It is pyrophoric, extremely flammable and may explode from heat, shock and/or friction. Because of the nature of silane, serious safety issues have been raised concerning the use, transportation, and storage of compressed gas cylinders of silane. Therefore it is desired to develop safer ways to deposit silicon-based films. In chapter III, I present the results of our research in the following fields: (1) Silane generator, (2) Substitutes of silane for deposition of silicon and silicon dioxide thin films, (3) Substitutes of silane for silicon dioxide thin film deposition. In chapter IV, hydropyridine is introduced as a new ligand for use in constructing precursors for chemical vapor deposition. Detachement of hydropyridine occurs by a low-temperature reaction leaving hydrogen in place of the hydropyridine ligands. Hydropyridine ligands can be attached to a variety of elements, including main group metals, such as aluminum and antimony, transition metals, such as titanium and tantalum, semiconductors such as silicon, and non-metals such as phosphorus and arsenic. In this study, hydropyridine-containing titanium compounds were synthesized and used as chemical vapor deposition precursors for deposition of titanium containing thin films. Some other titanium compounds were also studied for comparison. In chapter V, Chemical Vapor Depositions (CVD) of many oxide thin films including ferroelectric and high dielectric constant BaTiO3, SrTiO 3 and PbTiO3 films had been carried out under reduced pressure (30 torr--80 torr) using liquid precursors containing beta-diketone ligands. The relative reactivities of Ba(beta-diketonate)2, Sr(beta-diketonate) 2, Pb(beta-diketonate)2, Ti(beta-diketonate)3, TiO(beta-diketonate)2 and Ti(OiPr)2(beta-diketonate) 2 had been studied individually prior to the deposition of BaTiO 3, SrTiO3 and PbTiO3 thin films from the mixtures of corresponding precursors. By using multi-step deposition method, carbon free stoichiometric BaTiO3 thin films uniform in large area have been achieved.

Easy access to silicon(0) and silicon(II) compounds.

PubMed

Mondal, Kartik Chandra; Samuel, Prinson P; Tretiakov, Mykyta; Singh, Amit Pratap; Roesky, Herbert W; Stückl, A Claudia; Niepötter, Benedikt; Carl, Elena; Wolf, Hilke; Herbst-Irmer, Regine; Stalke, Dietmar

2013-04-15

Two different synthetic methodologies of silicon dihalide bridged biradicals of the general formula (L(n)•)2SiX2 (n = 1, 2) have been developed. First, the metathesis reaction between NHC:SiX2 and L(n): (L(n): = cyclic akyl(amino) carbene in a 1:3 molar ratio leads to the products 2 (n = 1, X = Cl), 4 (n = 2, X = Cl), 6 (n = 1, X = Br), and 7 (n = 2, X = Br). These reactions also produce coupled NHCs (3, 5) under C-C bond formation. The formation of the coupled NHCs (L(m) = cyclic alkyl(amino) carbene substituted N-heterocyclic carbene; m = 3, n = 1 (3) and m = 4, n =2 (5)) is faster during the metathesis reaction between NHC:SiBr2 and L(n): when compared with that of NHC:SiCl2. Second, the reaction of L(1):SiCl4 (8) (L(1): =:C(CH2)(CMe2)2N-2,6-iPr2C6H3) with a non-nucleophilic base LiN(iPr)2 in a 1:1 molar ratio shows an unprecedented methodology for the synthesis of the biradical (L(1)•)2SiCl2 (2). The blue blocks of silicon dichloride bridged biradicals (2, 4) are stable for more than six months under an inert atmosphere and in air for one week. Compounds 2 and 4 melt in the temperature range of 185 to 195 °C. The dibromide (6, 7) analogue is more prone to decomposition in the solution but comparatively more stable in the solid state than in the solution. Decomposition of the products has been observed in the UV-vis spectra. Moreover, compounds 2 and 4 were further converted to stable singlet biradicaloid dicarbene-coordinated (L(n):)2Si(0) (n = 1 (9), 2 (10)) under KC8 reduction. Compounds 2 and 4 were also reduced to dehalogenated products 9 and 10, respectively when treated with RLi (R = Ph, Me, tBu). Cyclic voltametry measurements show that 10 can irreversibly undergo both one electron oxidation and reduction.

Aminosilane functionalizations of mesoporous oxidized silicon for oligonucleotide synthesis and detection

PubMed Central

De Stefano, Luca; Oliviero, Giorgia; Amato, Jussara; Borbone, Nicola; Piccialli, Gennaro; Mayol, Luciano; Rendina, Ivo; Terracciano, Monica; Rea, Ilaria

2013-01-01

Direct solid phase synthesis of peptides and oligonucleotides (ONs) requires high chemical stability of the support material. In this work, we have investigated the passivation ability of porous oxidized silicon multilayered structures by two aminosilane compounds, 3-aminopropyltriethoxysilane and 3-aminopropyldimethylethoxysilane (APDMES), for optical label-free ON biosensor fabrication. We have also studied by spectroscopic reflectometry the hybridization between a 13 bases ON, directly grown on the aminosilane modified porous oxidized silicon by in situ synthesis, and its complementary sequence. Even if the results show that both devices are stable to the chemicals (carbonate/methanol) used, the porous silica structure passivated by APDMES reveals higher functionalization degree due to less steric hindrance of pores. PMID:23536541

Direct Human Contact with Siloxanes (Silicones) – Safety or Risk Part 1. Characteristics of Siloxanes (Silicones)

PubMed Central

Mojsiewicz-Pieńkowska, Krystyna; Jamrógiewicz, Marzena; Szymkowska, Katarzyna; Krenczkowska, Dominika

2016-01-01

Siloxanes are commonly known as silicones. They belong to the organosilicon compounds and are exclusively obtained by synthesis. Their chemical structure determines a range of physicochemical properties which were recognized as unique. Due to the susceptibility to chemical modifications, ability to create short, long or complex polymer particles, siloxanes found an application in many areas of human life. Siloxanes differ in particle size, molecular weight, shape and chemical groups. As a result, this determines the different physico-chemical properties, that directly affect the safety or the risk of their use. The areas that can be a source of danger to human health will be commented in this paper. PMID:27303296

Modulating the band structure and sub-bandgap absorption of Co-hyperdoped silicon by co-doping with shallow-level elements

NASA Astrophysics Data System (ADS)

Dong, Xiao; Fang, Xiuxiu; Wang, Yongyong; Song, Xiaohui; Lu, Zhansheng

2018-06-01

Hyperdoped group-III elements can lower the Fermi energy in the band structures of Co-hyperdoped silicon. When the Co-to-X (X = B, Al, Ga) ratio is 2:1, the intermediate band (IB) in the bandgap includes the Fermi energy and is partially filled by electrons, which is in accordance with the requirement of an IB material. The hyperdoped X atoms can cause the blueshift of the sub-bandgap absorption of the compound compared with the material with no shallow-level elements, which is due to the enlargement of the electronic excitation energy of the Co,X-co-doped silicon.

Electrochemical Synthesis of Binary and Ternary Refractory Compounds in the System Ti-Si-B from Chloride-Fluoride Melts

NASA Astrophysics Data System (ADS)

Devyatkin, Sergei V.

2007-09-01

Electrochemical synthesis of binary and ternary compounds in the system Ti-Si-B from chloridefluoride melts has been investigated by voltammetry and electrolysis. Electrochemical syntheses of titanium diboride, four titanium silicides (TiSi2, TiSi, Ti5Si4, Ti5Si3), silicon tetraboride and a new ternary compound, Ti5Si3B3, have been found to be one-step processes. The stoichiometry of the deposited compounds has been found to correlate with the bulk concentration of Ti, Si and B ions in the melt.

High Field Transport of Free Carriers at the SI-SIO2 Interface.

DTIC Science & Technology

1983-10-27

nuotbor) - Investigations of interface transport, ballistic transport and generally speaking high field transport in silicon and III-V compounds are...Tang and K. Hess, "Energy Diffusion Equation for an Electron Gas Interacting with Polar Optical Phonons: Non- Parabolic Case," Solid State...deformation potential electron-phonon scattering coeffi- cents is preented for elemental and compound semiconductors. Explesions for t acoustical defonoation

Research and preparation of ultra purity silicon tetrachloride

NASA Astrophysics Data System (ADS)

Wan, Ye; Zhao, Xiong; Yan, Dazhou; Yang, Dian; Li, Yunhao; Guo, Shuhu

2017-10-01

This article demonstrated a technology for producing ultra-purity silicon tetrachloride, which using the high purity SiCl4 as raw material through the method of combination ray reaction with purification. This technology could remove metal impurities and compounds impurities contained hydrogen effectively. The purity of product prepared by this technology can reach at 99.9999%, content of metal impurities can be low at 0.3PPb, meeting the requirement of industry easily. This technology has the advantages of simple process, continuous operation, and stable performance.

Performance of a Low-Cost, Low-Concentration Photovoltaic Module

NASA Astrophysics Data System (ADS)

Shell, Kara A.; Brown, Scott A.; Schuetz, Mark A.; Davis, Bob J.; French, Roger H.

2011-12-01

In order to significantly reduce the cost of solar power, Replex Plastics has developed a low-cost, low-concentration PV module incorporating acrylic mirror reflectors. The reflectors are compound parabolic concentrators designed for use with low-accuracy single axis trackers. The prototypes use crystalline silicon photovoltaic cells and achieved 7.1x concentration over a receiver without reflectors. The 1×1.6 m module used 1/10th the silicon of a standard module and produced a max power of 140 W.

Annealing group III-V compound doped silicon-germanium alloy for improved thermo-electric conversion efficiency

NASA Technical Reports Server (NTRS)

Vandersande, Jan W. (Inventor); Wood, Charles (Inventor); Draper, Susan L. (Inventor)

1989-01-01

The thermoelectric conversion efficiency of a GaP doped SiGe alloy is improved about 30 percent by annealing the alloy at a temperature above the melting point of the alloy, preferably stepwise from 1200 C to 1275 C in air to form large grains having a size over 50 microns and to form a GeGaP rich phase and a silicon rich phase containing SiP and SiO2 particles.

Thin film photovoltaic device with multilayer substrate

DOEpatents

Catalano, Anthony W.; Bhushan, Manjul

1984-01-01

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

In vivo contaminant partitioning to silicone implants: Implications for use in biomonitoring and body burden.

PubMed

O'Connell, Steven G; Kerkvliet, Nancy I; Carozza, Susan; Rohlman, Diana; Pennington, Jamie; Anderson, Kim A

2015-12-01

Silicone polymers are used for a wide array of applications from passive samplers in environmental studies, to implants used in human augmentation and reconstruction. If silicone sequesters toxicants throughout implantation, it may represent a history of exposure and potentially reduce the body burden of toxicants influencing the risk of adverse health outcomes such as breast cancer. Objectives of this research included identifying a wide variety of toxicants in human silicone implants, and measuring the in vivo absorption of contaminants into silicone and surrounding tissue in an animal model. In the first study, eight human breast implants were analyzed for over 1400 organic contaminants including consumer products, chemicals in commerce, and pesticides. A total of 14 compounds including pesticides such as trans-nonachlor (1.2-5.9ng/g) and p,p'-DDE (1.2-34ng/g) were identified in human implants, 13 of which have not been previously reported in silicone prostheses. In the second project, female ICR mice were implanted with silicone and dosed with p,p'-DDE and PCB118 by intraperitoneal injection. After nine days, silicone and adipose samples were collected, and all implants in dosed mice had p,p'-DDE and PCB118 present. Distribution ratios from silicone and surrounding tissue in mice compare well with similar studies, and were used to predict adipose concentrations in human tissue. Similarities between predicted and measured chemical concentrations in mice and humans suggest that silicone may be a reliable surrogate measure of persistent toxicants. More research is needed to identify the potential of silicone implants to refine the predictive quality of chemicals found in silicone implants. Copyright © 2015 Elsevier Ltd. All rights reserved.

Pressure-stabilized binary compounds of magnesium and silicon

NASA Astrophysics Data System (ADS)

Huan, Tran Doan

2018-02-01

The family of binary compounds composed of magnesium and silicon is rather rich. In addition to the well-known magnesium silicide Mg2Si , other compounds, including MgSi2, Mg4Si7 , Mg5Si6 , MgSi, and Mg9Si5 , have also been identified and/or proposed in precipitated Al-Mg-Si solid solutions. Nevertheless, computational studies show that only Mg2Si is thermodynamically stable at ambient conditions while certain nonzero hydrostatic pressure can stabilize Mg9Si5 so that it can coexist with Mg2Si . We conduct a comprehensive search for viable binary compounds of MgxSi1 -x (1 /3 ≤x ≤2 /3 ) , discovering numerous low-energy structures for all the compounds. On one hand, we find that MgSi2, MgSi, and Mg9Si5 are likely pressure-stabilized materials, while, on the other hand, supporting previous studies, we raise doubt on the existence of Mg5Si6 , and claim that the existence of Mg4Si7 remains an open question. Therefore, we recommend that (hydrostatic and/or nonhydrostatic) pressure should be explicitly considered when discussing the stability of these solids (and maybe other solids as well) by computations. We also find that MgSi2 can potentially exhibit superconducting behaviors within a wide range of pressure with the critical temperature of up to 7 K.

K- and L-edge X-ray absorption spectrum calculations of closed-shell carbon, silicon, germanium, and sulfur compounds using damped four-component density functional response theory.

PubMed

Fransson, Thomas; Burdakova, Daria; Norman, Patrick

2016-05-21

X-ray absorption spectra of carbon, silicon, germanium, and sulfur compounds have been investigated by means of damped four-component density functional response theory. It is demonstrated that a reliable description of relativistic effects is obtained at both K- and L-edges. Notably, an excellent agreement with experimental results is obtained for L2,3-spectra-with spin-orbit effects well accounted for-also in cases when the experimental intensity ratio deviates from the statistical one of 2 : 1. The theoretical results are consistent with calculations using standard response theory as well as recently reported real-time propagation methods in time-dependent density functional theory, and the virtues of different approaches are discussed. As compared to silane and silicon tetrachloride, an anomalous error in the absolute energy is reported for the L2,3-spectrum of silicon tetrafluoride, amounting to an additional spectral shift of ∼1 eV. This anomaly is also observed for other exchange-correlation functionals, but it is seen neither at other silicon edges nor at the carbon K-edge of fluorine derivatives of ethene. Considering the series of molecules SiH4-XFX with X = 1, 2, 3, 4, a gradual divergence from interpolated experimental ionization potentials is observed at the level of Kohn-Sham density functional theory (DFT), and to a smaller extent with the use of Hartree-Fock. This anomalous error is thus attributed partly to difficulties in correctly emulating the electronic structure effects imposed by the very electronegative fluorines, and partly due to inconsistencies in the spurious electron self-repulsion in DFT. Substitution with one, or possibly two, fluorine atoms is estimated to yield small enough errors to allow for reliable interpretations and predictions of L2,3-spectra of more complex and extended silicon-based systems.

Development of a Model and Computer Code to Describe Solar Grade Silicon Production Processes

NASA Technical Reports Server (NTRS)

Srivastava, R.; Gould, R. K.

1979-01-01

The program aims at developing mathematical models and computer codes based on these models, which allow prediction of the product distribution in chemical reactors for converting gaseous silicon compounds to condensed-phase silicon. The major interest is in collecting silicon as a liquid on the reactor walls and other collection surfaces. Two reactor systems are of major interest, a SiCl4/Na reactor in which Si(l) is collected on the flow tube reactor walls and a reactor in which Si(l) droplets formed by the SiCl4/Na reaction are collected by a jet impingement method. During this quarter the following tasks were accomplished: (1) particle deposition routines were added to the boundary layer code; and (2) Si droplet sizes in SiCl4/Na reactors at temperatures below the dew point of Si are being calculated.

A Microsystem Based on Porous Silicon-Glass Anodic Bonding for Gas and Liquid Optical Sensing

PubMed Central

De Stefano, Luca; Malecki, Krzysztof; Della Corte, Francesco G.; Moretti, Luigi; Rea, Ilaria; Rotiroti, Lucia; Rendina, Ivo

2006-01-01

We have recently presented an integrated silicon-glass opto-chemical sensor for lab-on-chip applications, based on porous silicon and anodic bonding technologies. In this work, we have optically characterized the sensor response on exposure to vapors of several organic compounds by means of reflectivity measurements. The interaction between the porous silicon, which acts as transducer layer, and the organic vapors fluxed into the glass sealed microchamber, is preserved by the fabrication process, resulting in optical path increase, due to the capillary condensation of the vapors into the pores. Using the Bruggemann theory, we have calculated the filled pores volume for each substance. The sensor dynamic has been described by time-resolved measurements: due to the analysis chamber miniaturization, the response time is only of 2 s. All these results have been compared with data acquired on the same PSi structure before the anodic bonding process.

Electron impact ionization of plasma important SiClX (X = 1-4) molecules: theoretical cross sections

NASA Astrophysics Data System (ADS)

Kothari, Harshit N.; Pandya, Siddharth H.; Joshipura, K. N.

2011-06-01

Electron impact ionization of SiClX (X = 1-4) molecules is less studied but an important process for understanding and modelling the interactions of silicon-chlorine plasmas with different materials. The SiCl3 radical is a major chloro-silicon species involved in the CVD (chemical vapour deposition) of silicon films from SiCl4/Ar microwave plasmas. We report in this paper the total ionization cross sections for electron collisions on these silicon compounds at incident energies from the ionization threshold to 2000 eV. We employ the 'complex scattering potential-ionization contribution' method and identify the relative importance of various channels, with ionization included in the cumulative inelastic scattering. New results are also presented on these exotic molecular targets. This work is significant in view of the paucity of theoretical studies on the radicals SiClX (X = 1-3) and on SiCl4.

A review of molecular beam epitaxy of ferroelectric BaTiO3 films on Si, Ge and GaAs substrates and their applications

PubMed Central

Mazet, Lucie; Yang, Sang Mo; Kalinin, Sergei V; Schamm-Chardon, Sylvie; Dubourdieu, Catherine

2015-01-01

SrTiO3 epitaxial growth by molecular beam epitaxy (MBE) on silicon has opened up the route to the monolithic integration of various complex oxides on the complementary metal-oxide–semiconductor silicon platform. Among functional oxides, ferroelectric perovskite oxides offer promising perspectives to improve or add functionalities on-chip. We review the growth by MBE of the ferroelectric compound BaTiO3 on silicon (Si), germanium (Ge) and gallium arsenide (GaAs) and we discuss the film properties in terms of crystalline structure, microstructure and ferroelectricity. Finally, we review the last developments in two areas of interest for the applications of BaTiO3 films on silicon, namely integrated photonics, which benefits from the large Pockels effect of BaTiO3, and low power logic devices, which may benefit from the negative capacitance of the ferroelectric. PMID:27877816

Coatings for graphite fibers

NASA Technical Reports Server (NTRS)

Galasso, F. S.; Scola, D. A.; Veltri, R. D.

1980-01-01

Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

Development of a Model and Computer Code to Describe Solar Grade Silicon Production Processes

NASA Technical Reports Server (NTRS)

Srivastava, R.; Gould, R. K.

1979-01-01

Mathematical models and computer codes based on these models, which allow prediction of the product distribution in chemical reactors for converting gaseous silicon compounds to condensed-phase silicon were developed. The following tasks were accomplished: (1) formulation of a model for silicon vapor separation/collection from the developing turbulent flow stream within reactors of the Westinghouse (2) modification of an available general parabolic code to achieve solutions to the governing partial differential equations (boundary layer type) which describe migration of the vapor to the reactor walls, (3) a parametric study using the boundary layer code to optimize the performance characteristics of the Westinghouse reactor, (4) calculations relating to the collection efficiency of the new AeroChem reactor, and (5) final testing of the modified LAPP code for use as a method of predicting Si(1) droplet sizes in these reactors.

Field Evaluation of Anti-Biofouling Compounds on Optical Instrumentation

NASA Technical Reports Server (NTRS)

McLean, Scott; Schofield, Bryan; Zibordi, Giuseppe; Lewis, Marlon; Hooker, Stanford; Weidemann, Alan

1997-01-01

Biofouling has been a serious question in the stability of optical measurements in the ocean, particularly in moored and drifting buoy applications. Many investigators coat optical surfaces with various compounds to reduce the amount of fouling; to our knowledge, however, there are no objective, in-situ comparative testing of these compounds to evaluate their effectiveness with respect to optical stability relative to untreated controls. We have tested a wide range of compounds at in-situ locations in Halifax Harbour and in the Adriatic Sea on passive optical sensors. Compounds tested include a variety of TBT formulations, antifungal agents, and low-friction silicone-based compounds; time-scales of up to four months were evaluated. The results of these experiments are discussed.

Acute bioassays and hazard evaluation of representative contaminants detected in Great Lakes fish

USGS Publications Warehouse

Passino, Dora R. May; Smith, Stephen B.

1987-01-01

We have provided a hazard ranking for 19 classes of compounds representing many of the nearly 500 organic compounds identified by gas chromatography-mass spectrometry in lake trout (Salvelinus namaycush) and walleye (Stizostedion vitreum vitreum) from the Great Lakes and Lake St. Clair. We initially made a provisional hazard ranking based on available published and unpublished information on aquatic toxicity, bioaccumulation, occurrence and sources. Acute toxicity tests with Daphnia pulex at 17A°C in reconstituted hard water were performed with 30 compounds representative of the 19 classes that were highest in the provisional ranking. The resulting toxicity data, along with information on the compounds' occurrence in Great Lakes fish and their sources, were ranked and weighted and then used in calculating the revised hazard ranking. The 10 most hazardous classes, in descending order, are as follows (values shown are mean 48-h EC50s, in μ/ml): arene halides (e.g., polychlorinated biphenyls, DDT), 0.0011; phthalate esters, 0.133; chlorinated camphenes (toxaphene), 0.0082; polyaromatic hydrocarbons (PAHs; e.g., dimethylnaphthalene) and reduced derivatives, 1.01; chlorinated fused polycyclics (e.g., trans-nonachlor), 0.022; nitrogen-containing compounds (e.g., O-methylhydroxyl-amine), 1.35; alkyl halides (e.g., (bromomethyl)cyclohexene), 10.1; cyclic alkanes (e.g., cyclododecane), 20.9; silicon-containing compounds (e.g., dimethyldiethoxy silane), 1.25; and heterocyclic nitrogen compounds (e.g., nicotine), 2.48. We recommend that chronic bioassays be conducted with fish and invertebrates to determine the sublethal effects of the following classes of compounds, for which few toxicity data are available: PAHs, heterocyclic nitrogen compounds, other nitrogen-containing compounds, alkyl halides, cyclic alkanes and silicon-containing compounds. Information from these types of studies will aid researchers in determining the possible causal role these contaminants play in the decline and reproductive impairment of Great Lakes fish.

A general classification of silicon utilizing organisms

NASA Astrophysics Data System (ADS)

Das, P.; Das, S.

2010-12-01

Silicon utilizing organisms may be defined as organisms with high silicon content (≥ 1% dry weight) and they can metabolize silicon with or without demonstrable silicon transporter genes (SIT) in them(Das,2010). Silicon is the second most abundant element in the lithosphere (27.70%) and it is as important as phosphorus and magnesium (0.03%) in the biota. Hydrated silica represents the second most abundant biogenic mineral after carbonate minerals. Silicon is accumulated and metabolized by some prokaryotes, and Si compounds can stimulate the growth of a range of fungi. It is well known that Si is essential for diatoms. In mammals, Si is considered an essential trace element, required in bone, cartilage and connective tissue formation, enzymatic activities and other metabolic processes. Silicon was suggested to act as a phosphoprotein effector in bone. In mammals, Si is also reported to positively influence the immune system and to be required for lymphocyte proliferation. The aqueous chemistry of Si is dominated by silicic acid at biological pH ranges. Monosilicic acid can form stable complexes with organic hydroxy-containing molecules . Biosilica also has been identified associated with various biomolecules including proteins and carbohydrates. There are main seven groups of silicon utilizing organisms belonging to Gram positive bacteria, algae, protozoa, sponges, fungi, lichens, and monocotyledon plants. In each group again all the members are not silicon utilizing organisms, thus selective members in each group are further classified depending their degree of silicon utilization. Important silicon utilizing bacteria are Mycobacteria, Nocardia, Streptomyces, Staphylococcus, Bacillus, Lactobacillus spp. etc., Important silicon utilizing algae are Centrobacillariophyceae, Pennatibacillariophyceae and Chrysophyceae. Many protozoa belonging to Heterokonta, Choanoflagellida, Actinopoda are well known silicon utilizing microorganisms. Hexactinellida ( glass sponges), Demospongiae and Sclerospongiae are important silicon utilizing sponges. Fungi like Aspergillus, Penicillium, Rhizopus etc. are also silicon utilizing. Candida spp. also belong to silicon utilizing organisms as they are also frequently found in sputum in silicotuberculosis cases. Many monocotyledon plants belonging to Pteridophyta, Magnoliophyta etc. are also well known silicon utilizing organisms. Almost all lichens belong to the group of silicon utilizing organisms.

Evaluation of three headspace sorptive extraction coatings for the determination of volatile terpenes in honey using gas chromatography-mass spectrometry.

PubMed

Cacho, J I; Campillo, N; Viñas, P; Hernández-Córdoba, M

2015-06-19

Headspace sorptive extraction (HSSE) was used to preconcentrate seven monoterpenes (eucalyptol, linalool, menthol, geraniol, carvacrol, thymol and eugenol) for separation by gas chromatography and mass spectrometry (GC-MS). Three commercially available coatings for the stir bars, namely Polydimethylsiloxane (PDMS), polyacrilate (PA) and Ethylene glycol-silicone (EG-Silicone), were tested, and the influential parameters both in the adsorption and the thermal desorption steps were optimized. PDMS provided the best sensitivity for linalool, geraniol, menthol and eucalyptol, whereas EG-Silicone was best for extracting the phenolic monoterpenes studied. Considering the average obtained slopes from all compounds, PDMS pointed as the best option, and the analytical characteristics for the HSSE-TD-GC-MS method using this coating were obtained. Quantification of the samples was carried out by matrix-matched calibration using a synthetic honey. Detection limits ranged between 0.007 and 0.032 ng g(-1), depending on the compound. Twelve honey samples of different floral origins were analyzed using the HSSE-GC-MS method, the analytes being detected at concentrations up to 64 ng g(-1). Copyright © 2015 Elsevier B.V. All rights reserved.

Accuracy and Precision of Silicon Based Impression Media for Quantitative Areal Texture Analysis

PubMed Central

Goodall, Robert H.; Darras, Laurent P.; Purnell, Mark A.

2015-01-01

Areal surface texture analysis is becoming widespread across a diverse range of applications, from engineering to ecology. In many studies silicon based impression media are used to replicate surfaces, and the fidelity of replication defines the quality of data collected. However, while different investigators have used different impression media, the fidelity of surface replication has not been subjected to quantitative analysis based on areal texture data. Here we present the results of an analysis of the accuracy and precision with which different silicon based impression media of varying composition and viscosity replicate rough and smooth surfaces. Both accuracy and precision vary greatly between different media. High viscosity media tested show very low accuracy and precision, and most other compounds showed either the same pattern, or low accuracy and high precision, or low precision and high accuracy. Of the media tested, mid viscosity President Jet Regular Body and low viscosity President Jet Light Body (Coltène Whaledent) are the only compounds to show high levels of accuracy and precision on both surface types. Our results show that data acquired from different impression media are not comparable, supporting calls for greater standardisation of methods in areal texture analysis. PMID:25991505

Evaluation of the Effect of Silicone Contamination on Various Bond Systems and the Feasibility of Removing the Contamination

NASA Technical Reports Server (NTRS)

Stanley, Stephanie D.

2008-01-01

Silicone is a contaminant that can cause catastrophic failure of a bond system depending on the materials and processes used to fabricate the bond system. Unfortunately, more and more materials are fabricated using silicone. The purpose of this testing was to evaluate which bond systems are sensitive to silicone contamination and whether or not a cleaning process could be utilized to remove the silicone to bring the bond system performance back to baseline. Due to the extensive nature of the testing, attempts will be made to generalize the understanding within classes of substrates, bond systems, and surface preparation and cleaning methods. This study was done by contaminating various metal (steel, Inconel, and aluminum), phenolic (carbon-cloth phenolic [CCP] and glass-cloth phenolic [GCP]), and rubber (natural rubber, asbestos-silicone dioxide filled natural butyldiene rubber [ASNBR]; silica-filled ethylene propylenediene monomer [SFEPDM], and carbon-filled ethylene propylenediene monomer [CFEPDM]) substrates which were then bonded using various adhesives and coatings (epoxy-based adhesives, paints, ablative compounds, and Chemlok adhesives) to determine the effect silicone contamination has on a given bond system's performance. The test configurations depended on the bond system being evaluated. The study also evaluated the feasibility of removing the silicone contamination by cleaning the contaminated substrate prior to bonding. The cleaning processes also varied depending on bond system.

High precision measurement of silicon in naphthas by ICP-OES using isooctane as diluent.

PubMed

Gazulla, M F; Rodrigo, M; Orduña, M; Ventura, M J; Andreu, C

2017-03-01

An analytical protocol for the accurate and precise determination of Si in naphthas is presented by using ICP-OES, optimizing from the sample preparation to the measurement conditions, in order to be able to analyze for the first time silicon contents below 100µgkg -1 in a relatively short time thus being used as a control method. In the petrochemical industry, silicon can be present as a contaminant in different petroleum products such as gasoline, ethanol, or naphthas, forming different silicon compounds during the treatment of these products that are irreversibly adsorbed onto catalyst surfaces decreasing its time life. The complex nature of the organic naphtha sample together with the low detection limits needed make the analysis of silicon quite difficult. The aim of this work is to optimize the measurement of silicon in naphthas by ICP-OES introducing as an improvement the use of isooctane as diluent. The set up was carried out by optimizing the measurement conditions (power, nebulizer flow, pump rate, read time, and viewing mode) and the sample preparation (type of diluent, cleaning process, blanks, and studying various dilution ratios depending on the sample characteristics). Copyright © 2016 Elsevier B.V. All rights reserved.

Recurrent laryngeal nerve regeneration through a silicone tube produces reinnervation without vocal fold mobility in rats.

PubMed

Kumai, Yoshihiko; Aoyama, Takashi; Nishimoto, Kohei; Sanuki, Tetsuji; Minoda, Ryosei; Yumoto, Eiji

2013-01-01

We established an animal model of recurrent laryngeal nerve reinnervation with persistent vocal fold immobility following recurrent laryngeal nerve injury. In 36 rats, the left recurrent laryngeal nerve was transected and the stumps were abutted in a silicone tube with a 1-mm interspace, facilitating regeneration. The mobility of the vocal folds was examined endoscopically 5, 10, and 15 weeks later. Electromyography of the thyroarytenoid muscle was performed. Reinnervation was assessed by means of a quantitative immunohistologic evaluation with anti-neurofilament antibody in the nerve both proximal and distal to the silicone tube. The atrophy of the thyroarytenoid muscle was assessed histologically. We observed that all animals had a fixed left vocal fold throughout the study. The average neurofilament expression in the nerve both distal and proximal to the silicone tube, the muscle area, and the amplitude of the compound muscle action potential recorded from the thyroarytenoid muscle on the treated side increased significantly (p < 0.05) over time, demonstrating regeneration through the silicone tube. Recurrent laryngeal nerve regeneration through a silicone tube produced reinnervation without vocal fold mobility in rats. The efficacy of new laryngeal reinnervation treatments can be assessed with this model.

Henry`s law constant for selected volatile organic compounds in high-boiling oils

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

Poddar, T.K.; Sirkar, K.K.

Absorption systems are often used to remove and recover organic vapors from process air/gas streams. A high boiling and inert liquid like silicone oil is an excellent absorbent for volatile organic compounds in air. Henry`s law constants of four different volatile organic compounds, namely, acetone, methanol, methylene chloride, and toluene between air and high-boiling oils were determined experimentally by the headspace-GC technique over a temperature range. The Henry`s law constants were fitted as a function of temperature to an equation.

Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study

PubMed Central

Yarapatineni, Rameshbabu; Vilekar, Abhishek; Kumar, J Phani; Kumar, G Ajay; Aravind, Prasad; Kumar, P Anil

2013-01-01

Background: This study was undertaken to compare the retention between sectional border molding using low fusing greenstick compound and single step border molding using condensation silicone (putty) impression material in three stages- A. Immediately following border molding, B. After final impression and C. With the finished permanent denture base. Materials & Methods: In this study evaluation of retentive values of sectional border molding (Group I) (custom impression trays border molded with green stick compound ) and single step border molding (Group II) ( border molding with condensation silicone (putty) impression material ). In both techniques definitive wash impression were made with light body condensation silicone and permanent denture base with heat cure polymerization resin. Results: Group II was significantly higher (mean=8011.43) than Group I (mean=5777.43) in test-A. The t-value (1.5883) infers that there was significant difference between Group I and Group II (p =0.15). Group I was significantly higher (mean=6718.57) than Group II (mean=5224.29) in test -B. The t-value (1.6909) infers that there was significant difference between Group I and Group II (p=0.17). Group II was higher (mean=4025.14) than Group I (mean=3835.07) in test -C. The t-value was 0.1239. But it was found to be statistically insignificant (p=0.005). Conclusion: Within the limitation of this clinical study border molding custom tray with low fusing green stick compound provided similar retention as compared to custom impression tray with condensation silicone in permanent denture base. How to cite this article: Yarapatineni R, Vilekar A, Kumar JP, Kumar GA, Aravind P, Kumar PA. Comparative evaluation of border molding, using two different techniques in maxillary edentulous arches - An in vivo study. J Int Oral Health 2013; 5(6):82-7 . PMID:24453450

Nucleation of the diamond phase in aluminium-solid solutions

NASA Technical Reports Server (NTRS)

Hornbogen, E.; Mukhopadhyay, A. K.; Starke, E. A., Jr.

1993-01-01

Precipitation was studied from fcc solid solutions with silicon, germanium, copper and magnesium. Of all these elements only silicon and germanium form diamond cubic (DC) precipitates in fcc Al. Nucleation of the DC structure is enhanced if both types of atom are dissolved in the fcc lattice. This is interpreted as due to atomic size effects in the prenucleation stage. There are two modes of interference of fourth elements with nucleation of the DC phase in Al + Si, Ge. The formation of the DC phase is hardly affected if the atoms (for example, copper) are rejected from the (Si, Ge)-rich clusters. If additional types of atom are attracted by silicon and/or germanium, DC nuclei are replaced by intermetallic compounds (for example Mg2Si).

Self-Assembly in Systems Containing Silicone Compounds

NASA Astrophysics Data System (ADS)

Ferreira, Maira Silva; Loh, Watson

2009-01-01

Chemical systems formed by silicone solvents and surfactants have potential applications in a variety of industrial products. In spite of their technological relevance, there are few reports on the scientific literature that focus on characterizing such ternary systems. In this work, we have aimed to develop a general, structural investigation on the phase diagram of one system that typically comprises silicone-based chemicals, by means of the SAXS (small-angle X-ray scattering) technique. Important features such as the presence of diverse aggregation states in the overall system, either on their own or in equilibrium with other structures, have been detected. As a result, optically isotropic chemical systems (direct and/or reversed microemulsions) and liquid crystals with lamellar or hexagonal packing have been identified and characterized.

Locking of electron spin coherence above 20 ms in natural silicon carbide

NASA Astrophysics Data System (ADS)

Simin, D.; Kraus, H.; Sperlich, A.; Ohshima, T.; Astakhov, G. V.; Dyakonov, V.

2017-04-01

We demonstrate that silicon carbide (SiC) with a natural isotope abundance can preserve a coherent spin superposition in silicon vacancies over an unexpectedly long time exceeding 20 ms. The spin-locked subspace with a drastically reduced decoherence rate is attained through the suppression of heteronuclear spin crosstalking by applying a moderate magnetic field in combination with dynamic decoupling from the nuclear spin baths. Furthermore, we identify several phonon-assisted mechanisms of spin-lattice relaxation and find that it can be extremely long at cryogenic temperatures, equal to or even longer than 10 s. Our approach may be extended to other polyatomic compounds and opens a path towards improved qubit memory for wafer-scale quantum technologies.

Application of surface analysis to solve problems of wear

NASA Technical Reports Server (NTRS)

Buckley, D. H.

1981-01-01

Results are presented for the use of surface analytical tools including field ion microscopy, Auger emission spectroscopy analysis (AES), cylindrical mirror Auger analysis and X-ray photoelectron spectroscopy (XPS). Data from the field ion microscope reveal adhesive transfer (wear) at the atomic level with the formation of surface compounds not found in the bulk, and AES reveals that this transfer will occur even in the presence of surface oxides. Both AES and XPS reveal that in abrasive wear with silicon carbide and diamond contacting the transition metals, the surface and the abrasive undergo a chemical or structural change which effects wear. With silicon carbide, silicon volatilizes leaving behind a pseudo-graphitic surface and the surface of diamond is observed to graphitize.

Compound Semiconductors for Low-Power p-Channel Field-Effect Transistors

DTIC Science & Technology

2009-07-01

making III–V FETs has been different than for silicon FETs. Growth techniques such as molecular beam epitaxy (MBE) are used to create heterostructures in...lities for III–V compounds. This article reviews the recent work to enhance hole mobilities in antimonide-based quantum wells. Epitaxial heterostructures...article reviews the recent work to enhance hole mobilities in antimonide-based quantum wells. Epitaxial heterostructures have been grown with the channel

Pressure-stabilized binary compounds of magnesium and silicon on Materials Project

DOE Data Explorer

Kristin Persson; Huan Tran

2018-04-13

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

Adhesives, fillers and potting compounds. Second progress report, December 1, 1967--April 1, 1968

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

Lichte, H.W.; Akst, I.B.

1968-12-31

Progress in the development program whose immediate purpose is to reduce set time of a silicone compound is described. Data are presented showing that a formulation of a current RTV silicone rubber with dibutyltin diacetate has a profitably lower set time than the same rubber in the present formulation which uses dibutyltin dilaurate, without increase in probability of either reversion or penalty to other weapons components. Time to set sufficiently to allow the next assembly step is 2 to 4 hours, compared to the 16 to 24 hours presently allowed or the 8 to 12 hours minimum attainable with themore » present formulation. The reduction is of the magnitude set as a goal, the attainment of which would increase production capacity enough to reduce the amount of new construction planned to accommodate weapons assembly programs.« less

Electronic Transmutation (ET): Chemically Turning One Element into Another.

PubMed

Zhang, Xinxing; Lundell, Katie A; Olson, Jared K; Bowen, Kit H; Boldyrev, Alexander I

2018-03-08

The concept of electronic transmutation (ET) depicts the processes that by acquiring an extra electron, an element with the atomic number Z begins to have properties that were known to only belong to its neighboring element with the atomic number Z+1. Based on ET, signature compounds and chemical bonds that are composed of certain elements can now be designed and formed by other electronically transmutated elements. This Minireview summarizes the recent developments and applications of ET on both the theoretical and experimental fronts. Examples on the ET of Group 13 elements into Group 14 elements, Group 14 elements into Group 15 elements, and Group 15 elements into Group 16 elements are discussed. Compounds and chemical bonding composed of carbon, silicon, germanium, phosphorous, oxygen and sulfur now have analogues using transmutated boron, aluminum, gallium, silicon, nitrogen, and phosphorous. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Facet-Selective Epitaxy of Compound Semiconductors on Faceted Silicon Nanowires.

PubMed

Mankin, Max N; Day, Robert W; Gao, Ruixuan; No, You-Shin; Kim, Sun-Kyung; McClelland, Arthur A; Bell, David C; Park, Hong-Gyu; Lieber, Charles M

2015-07-08

Integration of compound semiconductors with silicon (Si) has been a long-standing goal for the semiconductor industry, as direct band gap compound semiconductors offer, for example, attractive photonic properties not possible with Si devices. However, mismatches in lattice constant, thermal expansion coefficient, and polarity between Si and compound semiconductors render growth of epitaxial heterostructures challenging. Nanowires (NWs) are a promising platform for the integration of Si and compound semiconductors since their limited surface area can alleviate such material mismatch issues. Here, we demonstrate facet-selective growth of cadmium sulfide (CdS) on Si NWs. Aberration-corrected transmission electron microscopy analysis shows that crystalline CdS is grown epitaxially on the {111} and {110} surface facets of the Si NWs but that the Si{113} facets remain bare. Further analysis of CdS on Si NWs grown at higher deposition rates to yield a conformal shell reveals a thin oxide layer on the Si{113} facet. This observation and control experiments suggest that facet-selective growth is enabled by the formation of an oxide, which prevents subsequent shell growth on the Si{113} NW facets. Further studies of facet-selective epitaxial growth of CdS shells on micro-to-mesoscale wires, which allows tuning of the lateral width of the compound semiconductor layer without lithographic patterning, and InP shell growth on Si NWs demonstrate the generality of our growth technique. In addition, photoluminescence imaging and spectroscopy show that the epitaxial shells display strong and clean band edge emission, confirming their high photonic quality, and thus suggesting that facet-selective epitaxy on NW substrates represents a promising route to integration of compound semiconductors on Si.

Photovoltaic Science and Engineering Conference in Japan, 2nd, Tokyo, Japan, December 2-4, 1980, Proceedings

NASA Astrophysics Data System (ADS)

The state-of-the-art in amorphous solar cells is reviewed in terms of polycrystalline silicon solar cells, single crystal silicon solar cells, and methods of characterizing solar cells, including dielectric liquid immersion to increase cell efficiency. Compound semiconductor solar cells are explored, and new structures and advanced solar cell materials are discussed. Film deposition techniques for fabricating amorphous solar cells are presented, and the characterization, in addition to the physics and the performance, of amorphous solar cells are examined.

Multijunction photovoltaic device and fabrication method

DOEpatents

Arya, Rajeewa R.; Catalano, Anthony W.

1993-09-21

A multijunction photovoltaic device includes first and second amorphous silicon PIN photovoltaic cells in a stacked arrangement. An interface layer, composed of a doped silicon compound, is disposed between the two cells and has a lower bandgap than the respective n- and p-type adjacent layers of the first and second cells. The interface layer forms an ohmic contact with the one or the adjacent cell layers of the same conductivity type, and a tunnel junction with the other of the adjacent cell layers. The disclosed device is fabricated by a glow discharge process.

The evaporation study of silicon-containing ionic liquid

NASA Astrophysics Data System (ADS)

Chilingarov, Norbert S.; Medvedev, Artem A.; Deyko, Grigoriy S.; Kustov, Leonid M.; Chernikova, Elena A.; Glukhov, Lev M.; Polyakova, Marina V.; Ioutsi, Vitaliy A.; Markov, Vitaliy Yu.; Sidorov, Lev N.

2016-07-01

1,2-Dimethyl-3-(1‧,1‧,3‧,3‧-tetramethyl-3‧-phenyldisiloxanyl)methylimidazolium bis(trifluoromethanesulfonyl)amide ([PhC5OSi2MMIm+][Tf2N-]) is the first silicon-containing ionic liquid which was characterized with the vaporization enthalpy, (138.5 ± 1.8) kJ mol-1, and saturated vapor pressure, ln(p/Pa) = -(16656 ± 219)/(T/K) + (30.69 ± 0.92). This compound is a unique ionic liquid giving ions, retaining both cationic and anionic portions, in the electron impact ionization (EI) mass spectrum.

Form of silicon and method of making the same

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

Strobel, Timothy A.; Kim, Duck Young; Kurakevych, Oleksandr O.

The invention relates to a new phase of silicon, Si.sub.24, and a method of making the same. Si.sub.24 has a quasi-direct band gap, with a direct gap value of 1.34 eV and an indirect gap value of 1.3 eV. The invention also relates to a compound of the formula Na.sub.4Si.sub.24 and a method of making the same. N.sub.a4Si.sub.24 may be used as a precursor to make Si.sub.24.

Comparative Analysis of the Principal Characteristics of Microsilica Obtained from Silicon Manufacture Wastes and Used in Concrete Production Technologies

NASA Astrophysics Data System (ADS)

Balabanov, V. B.; Putsenko, K. N.

2017-11-01

On the basis of the survey of foreign and domestic literature over the past 65 years devoted to the study of the properties and the technology of applying microsilica in the capacity of modifying additives to concretes. Microsilica obtained as a by-product from the waste of ferroalloy plants and from the plants involved in production of silicon compounds is discussed. Analysis of the principal characteristics of different types of microsilica obtained from different sources is conducted.

1D silicon refractive lenses for surface scattering with high energy x-rays

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

Bertram, F.; Gutowski, O.; Schroer, C.

2016-07-27

At the high energy X-ray beamline P07 at PETRA III, 1D focusing down to 4 micrometer vertical beam height while preserving a horizontal beam width of 0.5 mm was established by refractive lenses etched into a silicon wafer. A single wafer with 8 different lens structures can cover the full energy range between 50 and 120 keV. For surface diffraction on ultrathin films a factor of 4 in intensity can be achieved compared to the already established Al-compound refractive 2D-lenses.

Silicone nasal prosthesis retained by an intranasal stent: a clinical report.

PubMed

Goveas, Reiyal; Puttipisitchet, Ongart; Shrestha, Binit; Thaworanunta, Sita; Srithavaj, M L Theerathavaj

2012-08-01

Nasal defects after tumor excision can leave a patient functionally and esthetically impaired. Loss of nasal septal cartilage support causes the soft tissue to collapse or undergo stenosis, further compounding the problem. Intranasal stents can be used to maintain the patency of such nasal defects. This clinical report describes the use of an acrylic resin nasal stent bonded to a silicone nasal prosthesis to rehabilitate a patient with a nasal defect. Copyright © 2012 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

Phase Equilibria of Stored Chemical Energy Reactants.

DTIC Science & Technology

1984-07-25

aluminate-lithium ferrate system. Detection of a Li1 Al4/7Fe 3/704 compound: C. R. Acad. Sci., Ser. C, V. 273, No. 15, p. 888-90. McNicol, B. D. and Pott...thermodynamic properties of lithium ferrate (LiO.5Fe2 .504) and lithium aluminate (LiO 5Al 2 504) from 5 to 545 K: J. Chem. Thermodyn., V. 7, No. 7, p. 693- 2...1977, Study of low-temperature hydrothermal crystallization in lithium oxide-silicon dioxide-water, potassium oxide-silicon dioxide-water, and

Determination of low solvent concentration by nano-porous silicon photonic sensors using volatile organic compound method.

PubMed

Bui, Huy; Pham, Van Hoi; Pham, Van Dai; Hoang, Thi Hong Cam; Pham, Thanh Binh; Do, Thuy Chi; Ngo, Quang Minh; Nguyen, Thuy Van

2018-05-07

A vast majority of the organic solvents used in industry and laboratories are volatile, hazardous and toxic organic compounds, they are considered as a potent problem for human health and a cause of environmental pollution. Although analytical laboratory methods can determine extremely low solvent concentration, the sensing method with low cost and high sensitivity remains a conundrum. This paper presents and compares three methods (volatile organic compound (VOC), liquid drop and saturated vapour pressure) for determination of organic solvents in liquid environment by using photonic sensor based on nano-porous silicon (pSi) microcavity structures. Among those, the VOC method provides the highest sensitivity at low solvent volume concentrations because it can create a high vapour pressure of the analyte on the sensor surface owing to the capillary deposition of organic solvent into the silicon pores. This VOC method consists of three steps: heating the solution with its particular boiling temperature, controlling the flowing gas through liquid and cooling sensor. It delivers the highest sensitivity of 6.9 nm/% at concentration of 5% and the limit of detection (LOD) of pSi-sensor is 0.014% in case of ethanol in water when using an optical system with a resolution of 0.1 nm. Especially, the VOC method is capable of detecting low volume concentration of methanol in two tested ethanol solutions of 30% (v/v) and 45% (v/v) with the LOD of pSi-sensor up to 0.01% and 0.04%, respectively. This result will help pave a way to control the quality of contaminated liquor beverages.

Copper-Catalyzed γ-Selective and Stereospecific Allylic Cross-Coupling with Secondary Alkylboranes.

PubMed

Yasuda, Yuto; Nagao, Kazunori; Shido, Yoshinori; Mori, Seiji; Ohmiya, Hirohisa; Sawamura, Masaya

2015-06-26

The scope of the copper-catalyzed coupling reactions between organoboron compounds and allylic phosphates is expanded significantly by employing triphenylphosphine as a ligand for copper, allowing the use of secondary alkylboron compounds. The reaction proceeds with complete γ-E-selectivity and preferential 1,3-syn stereoselectivity. The reaction of γ-silicon-substituted allylic phosphates affords enantioenriched α-stereogenic allylsilanes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical Reactions and Properties of Organosilicon Compounds Related to New Materials.

DTIC Science & Technology

1985-10-31

out. The compound behaves like an olefin in some reactions, for in- stance addition of hydrogen halides or chlorine: C1 2 HCI Mes 2 SiCl-SiClMes2...polymers have been synthesized which contain some silicon atoms bonded to hydrogen . These become crosslinked when mixed with substances containing several...and highly efficient catalysts, very small amounts are required in this process. Moreover, photocatalysis using polysilanes produces polymers with

Silylated Derivatives Retain Carbon and Alter Expected 13C-Tracer Enrichments Using Continuous Flow-Combustion-Isotope Ratio Mass Spectrometry

PubMed Central

Shinebarger, Steven R.; Haisch, Michael; Matthews, Dwight E.

2008-01-01

Continuous-flow inlets from oxidation reactors are commonly used systems for biological sample introduction into isotope ratio mass spectrometers (IRMS) to measure 13C enrichment above natural abundance. Because the samples must be volatile enough to pass through a gas chromatograph, silylated derivatization reactions are commonly used to modify biological molecules to add the necessary volatility. Addition of a t-butyldimethylsilyl (TBDMS) group is a common derivatization approach. However, we have found that samples do not produce the expected increment in measured 13C abundance as the TBDMS derivatives. We have made measurements of 13C enrichment of leucine and glutamate standards of known 13C enrichment using derivatives without silicon (N-acetyl n-propyl ester), with silicon (TBDMS), and an intermediate case. The measurements of 13C in amino acids derivatized without silicon were as expected. The 13C enrichment measurements using the TBDMS derivative were higher than expected, but could be corrected to produce the expected 13C enrichment measurement by IRMS if one carbon was removed per silicon. We postulate that the silicon in the derivative forms silicon carbide compounds in the heated cupric oxide reactor, rather than forming silicon dioxide. Doing so reduces the amount of CO2 formed from the carbon in the sample. Silylated derivatives retain carbon with the silicon and must be used carefully and with correction factors to measure 13C enrichments by continuous-flow IRMS. PMID:12510745

Analysis of Silicones Released from Household Items and Baby Articles by Direct Analysis in Real Time-Mass Spectrometry

NASA Astrophysics Data System (ADS)

Gross, Jürgen H.

2015-03-01

Direct analysis in real time-mass spectrometry (DART-MS) enables screening of articles of daily use made of polydimethylsiloxanes (PDMS), commonly known as silicone rubber, to assess their tendency to release low molecular weight silicone oligomers. DART-MS analyses were performed on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Flexible silicone baking molds, a watch band, and a dough scraper, as baby articles different brands of pacifiers, nipples, and a teething ring have been examined. While somewhat arbitrarily chosen, the set can be regarded as representative of household items, baby articles, and other objects made of silicone rubber. For comparison, two brands of silicone septa and as blanks a glass slide and a latex pacifier were included. Differences between the objects were mainly observed in terms of molecular weight distribution and occasional release of other compounds in addition to PDMS. Other than that, all objects made of silicone rubber released significant amounts of PDMS during DART analysis. To provide a coarse quantification, a calibration based on silicone oil was established, which delivered PDMS losses from 20 μg to >100 μg during the 16-s period per measurement. Also, the extraction of baking molds in rapeseed oil demonstrated a PDMS release at the level of 1 μg mg-1. These findings indicate a potential health hazard from frequent or long-term use of such items. This work does not intend to blame certain brands of such articles. Nonetheless, a higher level of awareness of this source of daily silicone intake is suggested.

Analysis of silicones released from household items and baby articles by direct analysis in real time-mass spectrometry.

PubMed

Gross, Jürgen H

2015-03-01

Direct analysis in real time-mass spectrometry (DART-MS) enables screening of articles of daily use made of polydimethylsiloxanes (PDMS), commonly known as silicone rubber, to assess their tendency to release low molecular weight silicone oligomers. DART-MS analyses were performed on a Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometer. Flexible silicone baking molds, a watch band, and a dough scraper, as baby articles different brands of pacifiers, nipples, and a teething ring have been examined. While somewhat arbitrarily chosen, the set can be regarded as representative of household items, baby articles, and other objects made of silicone rubber. For comparison, two brands of silicone septa and as blanks a glass slide and a latex pacifier were included. Differences between the objects were mainly observed in terms of molecular weight distribution and occasional release of other compounds in addition to PDMS. Other than that, all objects made of silicone rubber released significant amounts of PDMS during DART analysis. To provide a coarse quantification, a calibration based on silicone oil was established, which delivered PDMS losses from 20 μg to >100 μg during the 16-s period per measurement. Also, the extraction of baking molds in rapeseed oil demonstrated a PDMS release at the level of 1 μg mg(-1). These findings indicate a potential health hazard from frequent or long-term use of such items. This work does not intend to blame certain brands of such articles. Nonetheless, a higher level of awareness of this source of daily silicone intake is suggested.

REDUCTION OF CONCENTRATION POLARIZATION IN PERVAPORATION USING VIBRATING MEMBRANE MODULE

EPA Science Inventory

A vibrating membrane module currently marketed for filtration applications was evaluated for the separation of volatile organic compounds (VOCs) from aqueous solutions by pervaporation. Preliminary screening experiments with three VOCs, four silicone membranes, and in the presenc...

77 FR 20356 - Foreign-Trade Zone 277-Western Maricopa County, AZ; Application for Manufacturing Authority...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-04

... facility is used for the manufacture of 275 and 290 watt solar panels for industrial use. Components and... boxes, silicone sealant, putty/caulking compounds, plastic sheets, glass, tin-coated copper strips...

Incorporation of dopant impurities into a silicon oxynitride matrix containing silicon nanocrystals

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

Ehrhardt, Fabien; Muller, Dominique; Slaoui, Abdelilah, E-mail: abdelilah.slaoui@unistra.fr

2016-05-07

Dopant impurities, such as gallium (Ga), indium (In), and phosphorus (P), were incorporated into silicon-rich silicon oxynitride (SRSON) thin films by the ion implantation technique. To form silicon nanoparticles, the implanted layers were thermally annealed at temperatures up to 1100 °C for 60 min. This thermal treatment generates a phase separation of the silicon nanoparticles from the SRSON matrix in the presence of the dopant atoms. We report on the position of the dopant species within the host matrix and relative to the silicon nanoparticles, as well as on the effect of the dopants on the crystalline structure and the size ofmore » the Si nanoparticles. The energy-filtered transmission electron microscopy technique is thoroughly used to identify the chemical species. The distribution of the dopant elements within the SRSON compound is determined using Rutherford backscattering spectroscopy. Energy dispersive X-ray mapping coupled with spectral imaging of silicon plasmons was performed to spatially localize at the nanoscale the dopant impurities and the silicon nanoparticles in the SRSON films. Three different behaviors were observed according to the implanted dopant type (Ga, In, or P). The In-doped SRSON layers clearly showed separated nanoparticles based on indium, InOx, or silicon. In contrast, in the P-doped SRSON layers, Si and P are completely miscible. A high concentration of P atoms was found within the Si nanoparticles. Lastly, in Ga-doped SRSON the Ga atoms formed large nanoparticles close to the SRSON surface, while the Si nanoparticles were localized in the bulk of the SRSON layer. In this work, we shed light on the mechanisms responsible for these three different behaviors.« less

Tunable, antibacterial activity of silicone polyether surfactants.

PubMed

Khan, Madiha F; Zepeda-Velazquez, Laura; Brook, Michael A

2015-08-01

Silicone surfactants are used in a variety of applications, however, limited data is available on the relationship between surfactant structure and biological activity. A series of seven nonionic, silicone polyether surfactants with known structures was tested for in vitro antibacterial activity against Escherichia coli BL21. The compounds varied in their hydrophobic head, comprised of branched silicone structures with 3-10 siloxane linkages and, in two cases, phenyl substitution, and hydrophilic tail of 8-44 poly(ethylene glycol) units. The surfactants were tested at three concentrations: below, at, and above their Critical Micelle Concentrations (CMC) against 5 concentrations of E. coli BL21 in a three-step assay comprised of a 14-24h turbidometric screen, a live-dead stain and viable colony counts. The bacterial concentration had little effect on antibacterial activity. For most of the surfactants, antibacterial activity was higher at concentrations above the CMC. Surfactants with smaller silicone head groups had as much as 4 times the bioactivity of surfactants with larger groups, with the smallest hydrophobe exhibiting potency equivalent to sodium dodecyl sulfate (SDS). Smaller PEG chains were similarly associated with higher potency. These data link lower micelle stability and enhanced permeability of smaller silicone head groups to antibacterial activity. The results demonstrate that simple manipulation of nonionic silicone polyether structure leads to significant changes in antibacterial activity. Copyright © 2015 Elsevier B.V. All rights reserved.

Silicon-Containing Amino Acids: Synthetic Aspects, Conformational Studies, and Applications to Bioactive Peptides.

PubMed

Rémond, Emmanuelle; Martin, Charlotte; Martinez, Jean; Cavelier, Florine

2016-10-12

Unnatural α-amino acids form a family of essential molecules used for, among other applications, the synthesis of modified peptides, to improve resistance to proteolytic enzyme degradation, and to modulate physico- and biochemical properties of bioactive peptides as well as chiral inducers in asymmetric synthesis. Among them, silicon-containing unnatural amino acids are becoming an interesting new class of building blocks. The replacement of carbon atoms in bioactive substances with silicon is becoming increasingly popular. Peptides containing silyl amino acids hold great promise for maintaining or reinforcing the biological activity of active compounds, while they simultaneously enhance their resistance to enzyme degradation. In addition, the lipophilicity of the silicon atom facilitates their membrane crossing and their bioavailability. Nowadays, the interest of the pharmaceutical industry in peptide- and protein-based therapies is increasing. In this respect, silicon-containing amino acids and peptides are likely to be a significant part of future innovations in this area, and more generally in the area of biomolecules. In this process, commercial availability of silicon-containing amino acids is necessary: new syntheses have been developed, and work in this area is ongoing. This review aims to be a comprehensive and general summary of the different methods used to prepare silicon-containing amino acids and their implications on conformational structures and biological applications when they are incorporated into bioactive molecules.

Novel axially carborane-cage substituted silicon phthalocyanine photosensitizer; synthesis, characterization and photophysicochemical properties

NASA Astrophysics Data System (ADS)

Atmaca, Göknur Yaşa; Dizman, Cemil; Eren, Tarık; Erdoğmuş, Ali

2015-02-01

The novel axially dicarborane substituted silicon (IV) (SiPc-DC) phthalocyanine was synthesized by treating silicon phthalocyanine dichloride SiPc(Cl)2 (SiPc) with o-Carborane monool. The compound was characterized by mass spectrometry, UV-Vis, FT-IR, 1H and 11B Nuclear Magnetic Resonance Spectroscopy (NMR). Spectral, photophysical (fluorescence quantum yield) and photochemical (singlet oxygen (ΦΔ) and photodegradation quantum yield (Φd)) properties of the complex were reported in different solutions (Dimethyl sulfoxide (DMSO), Dimethylformamide (DMF) and Toluene). The results of spectral measurements showed that both SiPc and carborane cage can have potential to be used as sensitizers in photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) by their singlet oxygen efficiencies (ΦΔ = 0.41, 0.39).

Chemical nature of silicon nitride-indium phosphide interface and rapid thermal annealing for InP MISFETs

NASA Technical Reports Server (NTRS)

Biedenbender, M. D.; Kapoor, V. J.

1990-01-01

A rapid thermal annealing (RTA) process in pure N2 or pure H2 was developed for ion-implanted and encapsulated indium phosphide compound semiconductors, and the chemical nature at the silicon nitride-InP interface before and after RTA was examined using XPS. Results obtained from SIMS on the atomic concentration profiles of the implanted silicon in InP before and after RTA are presented, together with electrical characteristics of the annealed implants. Using the RTA process developed, InP metal-insulator semiconductor FETs (MISFETS) were fabricated. The MISFETS prepared had threshold voltages of +1 V, transconductance of 27 mS/mm, peak channel mobility of 1200 sq cm/V per sec, and drain current drift of only 7 percent.

Lewis Acidity of Bis(perfluorocatecholato)silane: Aldehyde Hydrosilylation Catalyzed by a Neutral Silicon Compound

DOE PAGES

Liberman-Martin, Allegra L.; Bergman, Robert G.; Tilley, T. Don

2015-04-16

Bis(perfluorocatecholato)silane Si(cat( F) 2 was prepared, and stoichiometric binding to Lewis bases was demonstrated with fluoride, triethylphosphine oxide, and N,N'-diisopropylbenzamide. The potent Lewis acidity of Si(cat( F) 2 was suggested from catalytic hydrosilylation and silylcyanation reactions with aldehydes. Mechanistic studies of hydrosilylation using an optically active silane substrate, R-(+)-methyl-(1-naphthyl)phenylsilane, proceeded with predominant stereochemical retention at silicon, consistent with a carbonyl activation pathway. The enantiospecificity was dependent on solvent and salt effects, with increasing solvent polarity or addition of NBu 4BAr( F) 4 leading to a diminished enantiomeric ratio. The medium effects are consistent with an ionic mechanism, wherein hydride transfermore » occurs prior to silicon-oxygen bond formation.« less

Porcelain enamel neutron absorbing material

DOEpatents

Iverson, D.C.

1987-11-20

A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compound of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved. 2 figs.

Investigations on the system boron-carbon silicon

NASA Technical Reports Server (NTRS)

Kieffer, R.; Gugel, E.; Leimer, G.; Ettmayer, P.

1983-01-01

The above elements form with each other binary compounds which are very interesting from the point of view of their structure and their chemistry and which are important for technology. The present investigation is concerned with the three-component system and the behavior of the binary compounds occurring in it. Investigations employing various techniques, such as X-ray, chemical analysis, microscopy and fusion experiments showed that no ternary phase exists within the boundary of the ternary system. There is no compound with a higher abrasion capacity than boron carbide. The probable phase field divisions at two isothermic intersections and the fusion isotherms are indicated.

Porcelain enamel neutron absorbing material

DOEpatents

Iverson, Daniel C.

1990-01-01

A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

Porcelain enamel neutron absorbing material

DOEpatents

Iverson, Daniel C.

1990-02-06

A porcelain enamel composition as a neutron absorbing material can be prepared of a major proportion by weight of a cadmium compound and a minor proportion of compounds of boron, lithium and silicon. These compounds in the form of a porcelain enamel coating or layer on several alloys has been found to be particularly effective in enhancing the nuclear safety of equipment for use in the processing and storage of fissile material. The composition of the porcelain enamel coating can be tailored to match the coefficient of thermal expansion of the equipment to be coated and excellent coating adhesion can be achieved.

Tuning of structural, light emission and wetting properties of nanostructured copper oxide-porous silicon matrix formed on electrochemically etched copper-coated silicon substrates

NASA Astrophysics Data System (ADS)

Naddaf, M.

2017-01-01

Matrices of copper oxide-porous silicon nanostructures have been formed by electrochemical etching of copper-coated silicon surfaces in HF-based solution at different etching times (5-15 min). Micro-Raman, X-ray diffraction and X-ray photoelectron spectroscopy results show that the nature of copper oxide in the matrix changes from single-phase copper (I) oxide (Cu2O) to single-phase copper (II) oxide (CuO) on increasing the etching time. This is accompanied with important variation in the content of carbon, carbon hydrides, carbonyl compounds and silicon oxide in the matrix. The matrix formed at the low etching time (5 min) exhibits a single broad "blue" room-temperature photoluminescence (PL) band. On increasing the etching time, the intensity of this band decreases and a much stronger "red" PL band emerges in the PL spectra. The relative intensity of this band with respect to the "blue" band significantly increases on increasing the etching time. The "blue" and "red" PL bands are attributed to Cu2O and porous silicon of the matrix, respectively. In addition, the water contact angle measurements reveal that the hydrophobicity of the matrix surface can be tuned from hydrophobic to superhydrophobic state by controlling the etching time.

GaAs photovoltaics and optoelectronics using releasable multilayer epitaxial assemblies.

PubMed

Yoon, Jongseung; Jo, Sungjin; Chun, Ik Su; Jung, Inhwa; Kim, Hoon-Sik; Meitl, Matthew; Menard, Etienne; Li, Xiuling; Coleman, James J; Paik, Ungyu; Rogers, John A

2010-05-20

Compound semiconductors like gallium arsenide (GaAs) provide advantages over silicon for many applications, owing to their direct bandgaps and high electron mobilities. Examples range from efficient photovoltaic devices to radio-frequency electronics and most forms of optoelectronics. However, growing large, high quality wafers of these materials, and intimately integrating them on silicon or amorphous substrates (such as glass or plastic) is expensive, which restricts their use. Here we describe materials and fabrication concepts that address many of these challenges, through the use of films of GaAs or AlGaAs grown in thick, multilayer epitaxial assemblies, then separated from each other and distributed on foreign substrates by printing. This method yields large quantities of high quality semiconductor material capable of device integration in large area formats, in a manner that also allows the wafer to be reused for additional growths. We demonstrate some capabilities of this approach with three different applications: GaAs-based metal semiconductor field effect transistors and logic gates on plates of glass, near-infrared imaging devices on wafers of silicon, and photovoltaic modules on sheets of plastic. These results illustrate the implementation of compound semiconductors such as GaAs in applications whose cost structures, formats, area coverages or modes of use are incompatible with conventional growth or integration strategies.

Ultrahigh Responsivity-Bandwidth Product in a Compact InP Nanopillar Phototransistor Directly Grown on Silicon

NASA Astrophysics Data System (ADS)

Ko, Wai Son; Bhattacharya, Indrasen; Tran, Thai-Truong D.; Ng, Kar Wei; Adair Gerke, Stephen; Chang-Hasnain, Connie

2016-09-01

Highly sensitive and fast photodetectors can enable low power, high bandwidth on-chip optical interconnects for silicon integrated electronics. III-V compound semiconductor direct-bandgap materials with high absorption coefficients are particularly promising for photodetection in energy-efficient optical links because of the potential to scale down the absorber size, and the resulting capacitance and dark current, while maintaining high quantum efficiency. We demonstrate a compact bipolar junction phototransistor with a high current gain (53.6), bandwidth (7 GHz) and responsivity (9.5 A/W) using a single crystalline indium phosphide nanopillar directly grown on a silicon substrate. Transistor gain is obtained at sub-picowatt optical power and collector bias close to the CMOS line voltage. The quantum efficiency-bandwidth product of 105 GHz is the highest for photodetectors on silicon. The bipolar junction phototransistor combines the receiver front end circuit and absorber into a monolithic integrated device, eliminating the wire capacitance between the detector and first amplifier stage.

Method for removing oxide contamination from silicon carbide powders

DOEpatents

Brynestad, J.; Bamberger, C.E.

1984-08-01

The described invention is directed to a method for removing oxide contamination in the form of oxygen-containing compounds such as SiO/sub 2/ and B/sub 2/O/sub 3/ from a charge of finely divided silicon carbide. The silicon carbide charge is contacted with a stream of hydrogen fluoride mixed with an inert gas carrier such as argon at a temperature in the range of about 200/sup 0/ to 650/sup 0/C. The oxides in the charge react with the heated hydrogen fluoride to form volatile gaseous fluorides such as SiF/sub 4/ and BF/sub 3/ which pass through the charge along with unreacted hydrogen fluoride and the carrier gas. Any residual gaseous reaction products and hydrogen fluoride remaining in the charge are removed by contacting the charge with the stream of inert gas which also cools the powder to room temperature. The removal of the oxygen contamination by practicing the present method provides silicon carbide powders with desirable pressing and sintering characteristics. 1 tab.

Electron-irradiation-induced crystallization at metallic amorphous/silicon oxide interfaces caused by electronic excitation

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

Nagase, Takeshi, E-mail: t-nagase@uhvem.osaka-u.ac.jp; Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1, Yamada-Oka, Suita, Osaka 565-0871; Yamashita, Ryo

2016-04-28

Irradiation-induced crystallization of an amorphous phase was stimulated at a Pd-Si amorphous/silicon oxide (a(Pd-Si)/SiO{sub x}) interface at 298 K by electron irradiation at acceleration voltages ranging between 25 kV and 200 kV. Under irradiation, a Pd-Si amorphous phase was initially formed at the crystalline face-centered cubic palladium/silicon oxide (Pd/SiO{sub x}) interface, followed by the formation of a Pd{sub 2}Si intermetallic compound through irradiation-induced crystallization. The irradiation-induced crystallization can be considered to be stimulated not by defect introduction through the electron knock-on effects and electron-beam heating, but by the electronic excitation mechanism. The observed irradiation-induced structural change at the a(Pd-Si)/SiO{sub x} and Pd/SiO{sub x}more » interfaces indicates multiple structural modifications at the metal/silicon oxide interfaces through electronic excitation induced by the electron-beam processes.« less

A review of molecular beam epitaxy of ferroelectric BaTiO 3 films on Si, Ge and GaAs substrates and their applications

DOE PAGES

Mazet, Lucie; Yang, Sang Mo; Kalinin, Sergei V.; ...

2015-06-30

SrTiO 3 epitaxial growth by molecular beam epitaxy (MBE) on silicon has opened up the route to the monolithic integration of various complex oxides on the complementary metal-oxide-semiconductor silicon platform. Among functional oxides, ferroelectric perovskite oxides offer promising perspectives to improve or add functionalities on-chip. We review the growth by MBE of the ferroelectric compound BaTiO 3 on silicon (Si), germanium (Ge) and gallium arsenide (GaAs) and we discuss the film properties in terms of crystalline structure, microstructure and ferroelectricity. Lastly, we review the last developments in two areas of interest for the applications of BaTiO 3 films on silicon,more » namely integrated photonics, which benefits from the large Pockels effect of BaTiO 3, and low power logic devices, which may benefit from the negative capacitance of the ferroelectric.« less

Ultrahigh Responsivity-Bandwidth Product in a Compact InP Nanopillar Phototransistor Directly Grown on Silicon

PubMed Central

Ko, Wai Son; Bhattacharya, Indrasen; Tran, Thai-Truong D.; Ng, Kar Wei; Adair Gerke, Stephen; Chang-Hasnain, Connie

2016-01-01

Highly sensitive and fast photodetectors can enable low power, high bandwidth on-chip optical interconnects for silicon integrated electronics. III-V compound semiconductor direct-bandgap materials with high absorption coefficients are particularly promising for photodetection in energy-efficient optical links because of the potential to scale down the absorber size, and the resulting capacitance and dark current, while maintaining high quantum efficiency. We demonstrate a compact bipolar junction phototransistor with a high current gain (53.6), bandwidth (7 GHz) and responsivity (9.5 A/W) using a single crystalline indium phosphide nanopillar directly grown on a silicon substrate. Transistor gain is obtained at sub-picowatt optical power and collector bias close to the CMOS line voltage. The quantum efficiency-bandwidth product of 105 GHz is the highest for photodetectors on silicon. The bipolar junction phototransistor combines the receiver front end circuit and absorber into a monolithic integrated device, eliminating the wire capacitance between the detector and first amplifier stage. PMID:27659796

An investigation of industrial molding compounds for use in 3D ultrasound, MRI, and CT imaging phantoms.

PubMed

Yunker, Bryan E; Cordes, Dietmar; Scherzinger, Ann L; Dodd, Gerald D; Shandas, Robin; Feng, Yusheng; Hunter, Kendall S

2013-05-01

This study investigated the ultrasound, MRI, and CT imaging characteristics of several industrial casting and molding compounds as a precursor to the future development of durable and anatomically correct flow phantoms. A set of usability and performance criteria was established for a proposed phantom design capable of supporting liquid flow during imaging. A literature search was conducted to identify the materials and methods previously used in phantom fabrication. A database of human tissue and casting material properties was compiled to facilitate the selection of appropriate materials for testing. Several industrial casting materials were selected, procured, and used to fabricate test samples that were imaged with ultrasound, MRI, and CT. Five silicones and one polyurethane were selected for testing. Samples of all materials were successfully fabricated. All imaging modalities were able to discriminate between the materials tested. Ultrasound testing showed that three of the silicones could be imaged to a depth of at least 2.5 cm (1 in.). The RP-6400 polyurethane exhibited excellent contrast and edge detail for MRI phantoms and appears to be an excellent water reference for CT applications. The 10T and 27T silicones appear to be usable water references for MRI imaging. Based on study data and the stated selection criteria, the P-4 silicone provided sufficient material contrast to water and edge detail for use across all imaging modalities with the benefits of availability, low cost, dimensional stability, nontoxic, nonflammable, durable, cleanable, and optical clarity. The physical and imaging differences of the materials documented in this study may be useful for other applications.

Production development of organic nonflammable spacecraft potting encapsulating and conformal coating compounds. Volume 2: Tables

NASA Technical Reports Server (NTRS)

Lieberman, S. L.

1974-01-01

Tables are presented which include: material properties; elemental analysis; silicone RTV formulations; polyester systems and processing; epoxy preblends and processing; urethane materials and processing; epoxy-urethanes elemental analysis; flammability test results, and vacuum effects.

Heterogeneous photocatalytic oxidation of atmospheric trace contaminants

NASA Technical Reports Server (NTRS)

Ollis, David F.; Peral, Jose

1992-01-01

A two year study to examine the feasibility of using heterogeneous photocatalysis for spacecraft air purification was begun at North Carolina State University on November 1, 1990. The original grant proposal included examination of the rates of destruction of anticipated spacecraft-generated air contaminants, including alcohols, aldehydes, chlorinated compounds, as well as trace levels of volatile compounds containing nitrogen, sulfur, and silicon. The progress made in the second six month period of 5/1/91-11/1/91 is discussed.

A study of the role of fillers in silicone rubber compounds for outdoor insulation

NASA Astrophysics Data System (ADS)

Meyer, Luiz Henrique

Polymeric materials are being used as a housing material on high voltage outdoor insulation as an alternative to porcelain or glass in line insulators, surge arresters, station posts, and bushings. Among the polymeric materials in use, silicone rubber has proven to have good aging performance under polluted conditions by keeping low levels of leakage current by virtue of its hydrophobicity. However, the exposure of polymeric materials to contaminated and humid environments can lead to certain surface conditions that reduces hydrophobicity increasing leakage current levels, giving rise to dry band arcing. Dry band arcing produces heat, which can result in tracking or erosion of the housing material. Although this dry band arcing does not harm porcelain or glass housings, it will erode pure silicone rubber to such an extent that its application in outdoor environments is not, practical. Fillers are added to silicone rubber to improve tracking and erosion resistance. Among the filler choices, alumina trihydrate (ATH) and silica have been extensively adopted in the compounding of polymeric housings. ATH is a flame retardant that has a molecular water in its formulation. Whenever the surface temperature of an ATH filled polymer reaches approximately 220°C, the water of hydration is released from the ATH molecule, what is recognized as an efficient way to cool down the surface, for example, in the case of dry band arcing. Alternatively, silica has very good bonding with the polymer backbone, imparting mechanical strength to the composite matrix. In addition, fillers such as ATH or silica increase the thermal conductivity of silicone rubber composites, which facilitates moving the heat away from its source, that is, from the origin of dry band arcing. Although heat is considered to be the main degradation factor when dry band arcing occurs, very little information is available on the thermal performance of filled silicone rubber. The standard methods available to test tracking and erosion resistance of filled silicone rubber do not allow to delineate the fundamentals of the thermal degradation, where the heat from the dry band arcing is the main degradation factor. In this work, a thermal imaging camera is used to investigate the thermal performance of filled silicone rubber in an inclined plane test. Infrared laser based techniques are developed to study the material performance. Furthermore, this thesis addresses the measurement of the thermal conductivity, based on infrared laser and thermal imaging, but using simple concepts. Theoretical and empirical models are developed in support of the experimental investigation.

Tripodal penta(p-phenylene) for the biofunctionalization of alkynyl-modified silicon surfaces

NASA Astrophysics Data System (ADS)

Sánchez-Molina, María; Díaz, Amelia; Valpuesta, María; Contreras-Cáceres, Rafael; López-Romero, J. Manuel; López-Ramírez, M. Rosa

2018-07-01

Here we report the optimization on the covalent grafting methodology of a tripod-shaped penta(p-phenylene), 1, on alkynyl-terminated silicon surfaces, and the incorporation of an active theophylline derivative, 2, for the specific immobilization of proteins. The tripodal molecule presents azide-terminal groups to be attached onto a silicon surface containing an alkynyl monolayer. Initially, compound 1 has been covalently incorporated on alkynyl-terminated Si wafers, by the copper catalyzed alkyne-azide 1,3-dipolar cycloaddition (CuAAC, a click reaction). The tripod density on the silicon surface is tuned by performing the CuAAC reaction at different concentrations of 1, as well as under different experimental conditions (T, base, copper source, shaking). Then, tripod 1-modified surface has also been biofunctionalized with 2. The effective preparation of this silicon-modified surface allowed us to study the streptavidin immobilization on the surface. Characterization of the different surfaces has been carried out by X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and Bright-Field Optical Transmission Microscopy (Confocal) techniques. We also include density functional theory (DFT) analysis of the organic structures to confirm the height-profile and the tripod-surface relative configuration extracted from AFM images.

Silicon solar cells: Past, present and the future

NASA Astrophysics Data System (ADS)

Lee, Youn-Jung; Kim, Byung-Sung; Ifitiquar, S. M.; Park, Cheolmin; Yi, Junsin

2014-08-01

There has been a great demand for renewable energy for the last few years. However, the solar cell industry is currently experiencing a temporary plateau due to a sluggish economy and an oversupply of low-quality cells. The current situation can be overcome by reducing the production cost and by improving the cell is conversion efficiency. New materials such as compound semiconductor thin films have been explored to reduce the fabrication cost, and structural changes have been explored to improve the cell's efficiency. Although a record efficiency of 24.7% is held by a PERL — structured silicon solar cell and 13.44% has been realized using a thin silicon film, the mass production of these cells is still too expensive. Crystalline and amorphous silicon — based solar cells have led the solar industry and have occupied more than half of the market so far. They will remain so in the future photovoltaic (PV) market by playing a pivotal role in the solar industry. In this paper, we discuss two primary approaches that may boost the silicon — based solar cell market; one is a high efficiency approach and the other is a low cost approach. We also discuss the future prospects of various solar cells.

Toxic Compounds in Our Food: Arsenic Uptake By Rice and Potential Mitigation By Silicon

NASA Astrophysics Data System (ADS)

Seyfferth, A.; Gill, R.; Penido, E.

2014-12-01

Arsenic is a ubiquitous element in soils worldwide and has the potential to negatively impact human and ecosystem health under certain biogeochemical conditions. While arsenic is relatively immobile in most oxidized soils due to a high affinity for soil solids, arsenic becomes mobilized under reduced soil conditions due to the reductive dissolution of iron(III) oxides thereby releasing soil-bound arsenic. Since arsenic is a well-known carcinogen, this plant-soil process has the potential to negatively impact the lives of billions of rice consumers worldwide upon plant uptake and grain storage of released arsenic. Moreover, arsenic uptake by rice is excacerbated by the use of As-laden groundwater for rice irrigation. One proposed strategy to decrease arsenic uptake by rice plants is via an increase in dissolved silicon in paddy soil solution (pore-water), since silicic acid and arsenous acid share an uptake pathway. However, several soil processes that influence arsenic cycling may be affected by silicon including desorption from bulk soil, formation and mineralogy of iron(III) oxide plaque, and adsorption/desorption onto/from iron plaque; the effect of silicon on these soil processes will ultimately dictate the effectiveness of altered dissolved silicon in decreasing arsenic uptake at the root, which in turn dictates the concentration of arsenic found in grains. Furthermore, the source of silicon may impact carbon cycling and, in particular, methane emissions. Here, impacts of altered dissolved silicon on processes that affect rhizospheric biogeochemical cycling of arsenic and subsequent plant-uptake, and how it influences other biogeochemical cycles such as carbon and iron are investigated. We show that silicon can decrease arsenic uptake and grain storage under certain conditions, and that altered silicon affects the type of iron (III) oxide that comprises iron plaque.

Covalently Bound Monomolecular Layers on Si Single Crystals

NASA Astrophysics Data System (ADS)

Chidsey, Christopher E. D.

1996-03-01

Methods and reagents borrowed from the molecular synthetic chemistry of silicon compounds have been used to form covalently bound monomolecular layers on silicon single crystals. Organic monolayers bound covalently to silicon could form the basis for silicon/organic interfaces useful in sensor structures. In a representative reaction, alkyl monolayers with densities approaching that of crystalline polyethylene have been prepared by the radical-initiated insertion of 1-alkenes into the Si-H bonds of hydrogen-terminated Si(111) surfaces footnote M. R. Linford, P. Fenter, P. M. Eisenberger and C. E. D Chidsey, J. Am. Chem. Soc. 117, 3145-3155 (1995). It has recently been found that this insertion reaction can also be initiated by illumination with UV light having sufficient energy to break the Si-H bond. Synchrotron-based high-resolution photoelectron spectroscopy and diffraction have demonstrated the expected Si-C bond in such monolayers footnote J. H. Terry, R. Cao, P. A. Pianetta, M. R. Linford and C. E. D. Chidsey, unpublished results. An alternate approach to similar monolayers has been found to be the chlorination of hydrogen-terminated Si(111) with Cl_2, followed by the nucleophilic displacement of chlorine with alkyl lithium reagents. The well-behaved chemical transformations of the hydrogen-terminated silicon surfaces appear to result from the essentially bulk termination of the silicon lattice with closed-shell silicon hydride "functional groups" on the surface. In addition to the formation of novel organic layers, a full understanding of the reactivity of the hydrogen-terminated silicon surfaces should lead to better control of key technological silicon interfaces such as Si/SiO_2, Si/epi-Si, and Si/metal.

Brazing process provides high-strength bond between aluminum and stainless steel

NASA Technical Reports Server (NTRS)

Huschke, E. G., Jr.; Nord, D. B.

1966-01-01

Brazing process uses vapor-deposited titanium and an aluminum-zirconium-silicon alloy to prevent formation of brittle intermetallic compounds in stainless steel and aluminum bonding. Joints formed by this process maintain their high strength, corrosion resistance, and hermetic sealing properties.

Potting procedure for electronic components

NASA Technical Reports Server (NTRS)

Rubino, A. G.; Zimmerman, J.

1977-01-01

Potting process is modified to effect a match more closely between embedded electronic components, potting mediums, and thermal environment. Application of room-temperature vulcanizing silicone rubber band cured in modified thermal cycle minimizes coil-to-resin adhesion and thus lowers stresses between transformer and potting compound.

Surface characterization of polydimethylsiloxane treated pharmaceutical glass containers by X-ray-excited photo- and Auger electron spectroscopy.

PubMed

Mundry, T; Surmann, P; Schurreit, T

2000-12-01

The siliconization of pharmaceutical glass containers is an industrially frequently applied procedure. It is done by spreading an aqueous silicone oil emulsion film on the inner surface and successive heat curing treatment at temperatures above 300 degrees C for 10-30 min. It was often proposed that a covalent bonding of PDMS to the glass or branching of the linear PDMS occurs during heat treatment. The present study was performed for a detailed investigation of the glass and silicone (polydimethylsiloxane = PDMS) chemical state before and after heat-curing treatment and analysis of the bond nature. Combined X-ray excited photoelectron (XPS) and Auger electron spectroscopy as well as angle resolved XPS-measurements were used for analysis of the glass samples. The silicon surface atoms of the borosilicate container glass were transformed to a quartz-like compound whereas the former linear PDMS had a branched, two-dimensional structure after the heat curing treatment. It was concluded that the branching indicates the formation of new siloxane bonds to the glass surface via hydroxyl groups. Further evidence for the presence of bonded PDMS at the glass surface can be found in the valence band spectra of the siliconized and untreated samples. However, this bond could not be detected directly due to its very similar nature to the siloxane bonds of the glass matrix and the organosilicon backbone of PDMS. Due to the high variation of data from the siliconized samples it was concluded, that the silicone film is not homogeneous. Previously raised theories of reactions during heat-curing glass siliconization are supported by the XPS data of this investigation. Yet, the postulation of fixing or baking the silicone on the glass surface is only partially true since the bonded layer is very thin and most of the silicone originally on the surface after heat curing can be removed by suitable solvents. This fraction can therefore still interact with drug products being in contact to the siliconized container wall.

The Status and Outlook for the Photovoltaics Industry

NASA Astrophysics Data System (ADS)

Carlson, David

2006-03-01

The first silicon solar cell was made at Bell Labs in 1954, and over the following decades, shipments of photovoltaic (PV) modules increased at a rate of about 18% annually. In the last several years, the annual growth rate has increased to ˜ 35% due largely to government-supported programs in Japan and Germany. Silicon technology has dominated the PV industry since its inception, and in 2005 about 65% of all solar cells were made from polycrystalline (or multicrystalline) silicon, 24% from monocrystalline silicon and ˜ 4% from ribbon silicon. While conversion efficiencies as high as 24.7% have been obtained in the laboratory for silicon solar cells, the best efficiencies for commercial PV modules are in the range of 17 18% (the efficiency limit for a silicon solar cell is ˜ 29%). A number of companies are commercializing solar cells based on other materials such as amorphous silicon, microcrystalline silicon, cadmium telluride, copper-indium-gallium-diselenide (CIGS), gallium arsenide (and related compounds) and dye- sensitized titanium oxide. Thin film CIGS solar cells have been fabricated with conversion efficiencies as high as 19.5% while efficiencies as high as 39% have been demonstrated for a GaInP/Ga(In)As/Ge triple-junction cell operating at a concentration of 236 suns. Thin film solar cells are being used in consumer products and in some building-integrated applications, while PV concentrator systems are being tested in grid-connected arrays located in high solar insolation areas. Nonetheless, crystalline silicon PV technology is likely to dominate the terrestrial market for at least the next decade with module efficiencies > 20% and module prices of < 1/Wp expected by 2020, which in turn should allow significant penetration of the utility grid market. However, crystalline silicon solar cells may be challenged in the next decade or two by new low-cost, high performance devices based on organic materials and nanotechnology.

High-pressure synthesis, amorphization, and decomposition of silane.

PubMed

Hanfland, Michael; Proctor, John E; Guillaume, Christophe L; Degtyareva, Olga; Gregoryanz, Eugene

2011-03-04

By compressing elemental silicon and hydrogen in a diamond anvil cell, we have synthesized polymeric silicon tetrahydride (SiH(4)) at 124 GPa and 300 K. In situ synchrotron x-ray diffraction reveals that the compound forms the insulating I4(1)/a structure previously proposed from ab initio calculations for the high-pressure phase of silane. From a series of high-pressure experiments at room and low temperature on silane itself, we find that its tetrahedral molecules break up, while silane undergoes pressure-induced amorphization at pressures above 60 GPa, recrystallizing at 90 GPa into the polymeric crystal structures.

Effects of different processing techniques on multi-walled carbon nanotubes/silicone rubber nanocomposite on tensile strength properties

NASA Astrophysics Data System (ADS)

Mazlan, N.; Jaafar, M.; Aziz, A.; Ismail, H.; Busfield, J. J. C.

2016-10-01

In this work, two different processing techniques were approached to identify the properties of the multi-walled carbon nanotubes (MWCNT) reinforced polydimethylsiloxane (PDMS). The MWCNT was dispersed in the polymer by using the ultrasonic and twin screw extruder mixer. The final composite showed different manner of dispersed tubes in the silicone rubber matrix. High shear twin screw extruder tends to fragment the tubes during processing compound, which can be observed by scanning electron microscope (SEM). Tensile strength of the extrusion MWCNT/PDMS nanocomposites was found to be higher compared to ultrasonic MWCNT/PDMS nanocomposites.

Filler migration and extensive lesions after lip augmentation: Adverse effects of polydimethylsiloxane filler.

PubMed

Abtahi-Naeini, Bahareh; Faghihi, Gita; Shahmoradi, Zabihollah; Saffaei, Ali

2018-01-07

Polydimethylsiloxane (PDMS), also called liquid silicone, belongs to a group of polymeric compounds that are commonly referred to as silicones. These filling agents have been used as injectable filler for soft tissue augmentation. There are limited experiences about management of the severe complications related to filler migration associated with PDMS injection. We present a 35-year-old female with severe erythema, edema over her cheeks and neck, and multiple irregularities following cosmetic lip augmentation with PDMS. Further studies are required for management of this complicated case of PDMS injection. © 2018 Wiley Periodicals, Inc.

Application of compound parabolic concentrators to solar photovoltaic conversion. Final report

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

Cole, R.L.; Gorski, A.J.; Graven, R.M.

1977-02-01

The final results of an analytical and experimental study of the application of nonimaging concentrators to solar photovoltaic conversion are presented. Two versions of the Compound Parabolic Concentrator (CPC) were considered, the Dielectric Compound Parabolic Concentrator (DCPC) in which the concentrator is filled with a dielectric material that satisfies requirements for Total Internal Reflection (TIR), and a conventional CPC in which metallic reflection is used for the mirror surfaces. Two working prototype panels were constructed and tested during the course of the program. The first was a 1.22 m by 1.22 m DCPC panel that requires only ten adjustments/year, hasmore » a panel utilization factor (packing factor) of 96%, and delivered the equivalent of 138 W (peak) under 1 kW/m/sup 2/ direct insolation. The net energy conversion efficiency was 10.3% over the entire panel area. The second panel was a conventional CPC panel measuring 1.22 m by 1.22 m. This panel requires thirty-six adjustments per year, and delivers the equivalent of 97 W when under 1 kW/m/sup 2/ direct insolation. The results of a cost-effectiveness analysis of the concept of using nonimaging concentrators for photovoltaic conversion are also presented. The concentrator panels showed a decided savings in comparison to the cost of flat plate photovoltaic panels, both at present-day silicon costs ($2000/m/sup 2/) and projected lower silicon costs ($200/m/sup 2/). At a silicon cost of $200/m/sup 2/, a two-dimensional (cone) version of the collector has the potential for achieving from $0.60-2.00 per average watt (about $0.15-0.50 per peak watt) while requiring only crude (+-4.5/sup 0/) tracking.« less

Organic silicon compounds anf hydrogen sulfide removal from biogas by mineral and adsorbent

NASA Astrophysics Data System (ADS)

Choi, J.

2015-12-01

Biogas utilized for energy production needs to be free from organic silicon compounds and hydrogen sulfide , as their burning has damaging effects on utilities and humans; organic silicon compounds and hydrogen sulfide can be found in biogas produced from biomass wastes, due to their massive industrial use in synthetic product,such as cosmetics, detergents and paints.Siloxanes and hydrogen sulfide removal from biogas can be carried out by various methods (Ajhar et al., 2010); aim of the present work is to find a single practical andeconomic way to drastically and simultaneously reduce both hydrogen sulfide and the siloxanes concentration to less than 1 ppm. Some commercial activated carbons previously selected (Monteleoneet al., 2011) as being effective in hydrogen sulfide up taking have been tested in an adsorption measurement apparatus, by flowing both hydrogen sulphide and volatile siloxane (Decamethycyclopentasiloxane or D5) in a nitrogen stream,typically 25-300 ppm D5 over N2, through an clay minerals, Fe oxides and Silica; the adsorption process was analyzed by varying some experimental parameters (concentration, grain size, bed height). The best silica shows an adsorption capacity of 0.2 g D5 per gram of silica. The next thermo gravimetric analysis (TGA) confirms the capacity data obtained experimentally by the breakthrough curve tests.The capacity results depend on D5 and hydrogen sulphide concentrations. A regenerative silica process is then carried out byheating the silica bed up to 200 ° C and flushing out the adsorbed D5 and hydrogen sulphide samples in a nitrogen stream in athree step heating procedure up to 200 ° C. The adsorption capacity is observed to degrade after cyclingthe samples through several adsorption-desorption cycles.

Development of a standard gas generating vial comprised of a silicon oil-polystyrene/divinylbenzene composite sorbent.

PubMed

Grandy, Jonathan J; Gómez-Ríos, German A; Pawliszyn, Janusz

2015-09-04

In this work, a highly reproducible standard gas generating vial is proposed. The vial is comprised of a silicon diffusion pump oil spiked with an appropriate calibration compound, such as modified McReynolds probes (benzene, 2-pentanone, pyridine, 1-nitropropane, 1-pentanol, and n-octane), and then mixed with polystyrene/divinylbenzene (PS/DVB) particles. The concentrations of these compounds in gaseous headspace were found to substantially decrease in comparison to previously developed hydrocarbon pump oil based vials; hence, the amount of standard loaded onto SPME fibers was at most, half that of the previous vial design. Depletion for all compounds after 208 successive extractions was shown to be less than 3.5%. Smaller quantities of standards being used resulted in a vial that depleted slower while remaining statistically repeatable over a wider number of runs. Indeed, it was found that depletion could be largely predicted by using a mass balance theoretical model. This behavior allowed a further increase in the number of loadings that could be performed repeatedly. At a 95% level of confidence, the ANOVA test demonstrated that the prepared vials were statistically identical, with no significant intra- or inter-batch differences. In addition, it was found that vials stored under different conditions (e.g. under light exposure, room temperature, and within a refrigerator) were stable over 10 weeks. Silicon based vials proved to be ideal for performing instrument quality control and loading of internal standards onto fibers, both of which are of great importance when performing on-site analysis using portable GC-MS instrumentation and high throughput determinations in laboratory. Copyright © 2015 Elsevier B.V. All rights reserved.

Deposition of silicon oxynitride films by low energy ion beam assisted nitridation at room temperature

NASA Astrophysics Data System (ADS)

Youroukov, S.; Kitova, S.; Danev, G.

2008-05-01

The possibility is studied of growing thin silicon oxynitride films by e-gun evaporation of SiO and SiO2 together with concurrent bombardment with low energy N2+ ions from a cyclotron resonance (ECR) source at room temperature of substrates. The degree of nitridation and oxidation of the films is investigated by means of X-ray spectroscopy. The optical characteristics of the films, their environmental stability and adhesion to different substrates are examined. The results obtained show than the films deposited are transparent. It is found that in the case of SiO evaporation with concurrent N2+ ion bombardment, reactive implantation of nitrogen within the films takes place at room temperature of the substrate with the formation of a new silicon oxynitride compound even at low ion energy (150-200 eV).

Lewis-Base-Mediated Diastereoselective Silylations of Alcohols: Synthesis of Silicon-Stereogenic Dialkoxysilanes Controlled by Chiral Aryl BINMOLs.

PubMed

Bai, Xing-Feng; Zou, Jin-Feng; Chen, Mu-Yi; Xu, Zheng; Li, Li; Cui, Yu-Ming; Zheng, Zhan-Jiang; Xu, Li-Wen

2017-07-18

In the past years, stereoselective functionalizations of hydroxyl groups of alcohol substrates with chlorosilanes leading to silyl ether formation have evolved from a functional-group protection to an enantioselective synthetic strategy. This work comprises a controlled desymmetrization of dichlorosilanes by using a family of structurally specific chiral diols, chiral 1,1'-binaphthalene-2-α-arylmethanol-2'-ol (Ar-BINMOL). This process led to the facile construction of silicon-stereogenic organosilicon compounds with high yields and good diastereoselectivities. In addition, the diasteroselective silylation of chiral diols might not only be of interest for the development of highly stereoselective nucleophilic silylation, but also shed light on the construction of novel chiral phosphine ligands bearing a silicon-stereogenic center. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Adsorption and desorption characteristics of gradient distributed Bragg reflector porous silicon layers.

PubMed

Um, Sungyong; Lee, Sung Gi; Woo, Hee-Gweon; Cho, Sungdong; Sohn, Honglae

2013-01-01

Adsorption and desorption characteristics of gradient distributed Bragg reflector (DBR) porous silicon (PSi) were investigated under the exposure of organic vapors. Gradient DBR PSi whose average pore size decreased as the lateral distance from the Pt electrode increased was generated by using an asymmetric etching configuration. The reflection resonances were measured as a function of lateral distance from a point closest to the plate Pt electrode to a position on the silicon surface. Two types of gradient DBR PSi (H- and HO-terminated gradient DBR PSi) were used in this study. The detection of volatile organic compounds (VOCs) using the gradient DBR PSi had been achieved. When the vapor of VOCs condensed in the nanopores, the gradient DBR PSi modified with hydrophobic and hydrophilic functionality exhibited different pore adsorption and desorption characteristics.

Silicon(IV) phthalocyanines substituted axially with different nucleoside moieties. Effects of nucleoside type on the photosensitizing efficiencies and in vitro photodynamic activities.

PubMed

Zheng, Bi-Yuan; Shen, Xiao-Min; Zhao, Dong-Mei; Cai, Yi-Bin; Ke, Mei-Rong; Huang, Jian-Dong

2016-06-01

A series of new silicon(IV) phthalocyanines (SiPcs) di-substituted axially with different nucleoside moieties have been synthesized and evaluated for their singlet oxygen quantum yields (ΦΔ) and in vitro photodynamic activities. The adenosine-substituted SiPc shows a lower photosensitizing efficiency (ΦΔ=0.35) than the uridine- and cytidine-substituted analogs (ΦΔ=0.42-0.44), while the guanosine-substituted SiPc exhibits a weakest singlet oxygen generation efficiency with a ΦΔ value down to 0.03. On the other hand, replacing axial adenosines with chloro-modified adenosines and purines can result in the increase of photogenerating singlet oxygen efficiencies of SiPcs. The formed SiPcs 1 and 2, which contain monochloro-modified adenosines and dichloro-modified purines respectively, appear as efficient photosensitizers with ΦΔ of 0.42-0.44. Both compounds 1 and 2 present high photocytotoxicities against HepG2 and BGC823 cancer cells with IC50 values ranging from 9nM to 33nM. The photocytotoxicities of these two compounds are remarkably higher than the well-known anticancer photosensitizer, chlorin e6 (IC50=752nM against HepG2 cells) in the same condition. As revealed by confocal microscopy, for both cell lines, compound 1 can essentially bind to mitochondria, while compound 2 is just partially localized in mitochondria. In addition, the two compounds induce cell death of HepG2 cells likely through apoptosis. Copyright © 2016 Elsevier B.V. All rights reserved.

Preparations and properties of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials.

PubMed

Watanabe, Shoji

2008-01-01

This short review describes various types of anti-corrosion additives of water-soluble metal working fluids for aluminum alloy materials. It is concerned with synthetic additives classified according to their functional groups; silicone compounds, carboxylic acids and dibasic acids, esters, Diels-Alder adducts, various polymers, nitrogen compounds, phosphoric esters, phosphonic acids, and others. Testing methods for water-soluble metal working fluids for aluminum alloy materials are described for a practical application in a laboratory.

Chemical and structural order in silicon oxynitrides by methods of surface physics

NASA Astrophysics Data System (ADS)

Finster, J.; Heeg, J.; Klinkenberg, E.-D.

A large number of thin amorphous layers of SiO xN y and several (crystalline) reference compounds (SiO 2, Si 3N 4, Si 2N 2O) are studied. Although XANES and SEXAFS are well sulted to derive structural and chemical order, for these compounds many problems remain to be solved. We show how core level spectra (XPS, AES) can be used to gain such information (e.g. random bonding structure, N coordination, oxidation behaviour).

Effect of Fermentation Broths on Performance of Hydrophobic Zeolite-Silicone Rubber Mixed Matrix Pervaporation Membranes

EPA Science Inventory

Fermentative organisms produce a range of compounds in addition to the desired product. For example, in addition to ethanol, standard yeast produce longer straight-chained and branched alcohols and organic acids. Additionally, biomass pretreatment process, particularly acid-bas...

Photoluminescence of etched SiC nanowires

NASA Astrophysics Data System (ADS)

Stewart, Polite D., Jr.; Rich, Ryan; Zerda, T. W.

2010-10-01

SiC nanowires were produced from carbon nanotubes and nanosize silicon powder in a tube furnace at temperatures between 1100^oC and 1350^oC. SiC nanowires had average diameter of 30 nm and very narrow size distribution. The compound possesses a high melting point, high thermal conductivity, and excellent wear resistance. The surface of the SiC nanowires after formation is covered by an amorphous layer. The composition of that layer is not fully understood, but it is believed that in addition to amorphous SiC it contains various carbon and silicon compounds, and SiO2. The objective of the research was to modify the surface structure of these SiC nanowires. Modification of the surface was done using the wet etching method. The etched nanowires were then analyzed using Fourier Transform Infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and photoluminescence (PL). FTIR and TEM analysis provided valid proof that the SiC nanowires were successfully etched. Also, the PL results showed that the SiC nanowire core did possess a fluorescent signal.

Characterization of high explosive particles using cluster secondary ion mass spectrometry.

PubMed

Gillen, Greg; Mahoney, Christine; Wight, Scott; Lareau, Richard

2006-01-01

The use of secondary ion mass spectrometry (SIMS) for the detection and spatially resolved analysis of individual high explosive particles is described. A C(8) (-) carbon cluster primary ion beam was used in a commercial SIMS instrument to analyze samples of high explosives dispersed as particles on silicon substrates. In comparison with monatomic primary ion bombardment, the carbon cluster primary ion beam was found to greatly enhance characteristic secondary ion signals from the explosive compounds while causing minimal beam-induced degradation. The resistance of these compounds to degradation under ion bombardment allows explosive particles to be analyzed under high primary ion dose bombardment (dynamic SIMS) conditions, facilitating the rapid acquisition of spatially resolved molecular information. The use of cluster SIMS combined with computer control of the sample stage position allows for the automated identification and counting of explosive particle distributions on silicon surfaces. This will be useful for characterizing the efficiency of transfer of particulates in trace explosive detection portal collectors and/or swipes utilized for ion mobility spectrometry applications.

Viscoelastic properties of elastomeric materials for O-ring applications

NASA Technical Reports Server (NTRS)

Bower, Mark V.

1989-01-01

Redesign of the Space Shuttle Solid Rocket Booster necessitated re-evaluation of the material used in the field joint O-ring seals. This research project was established to determine the viscoelastic characteristics of five candidate materials. The five materials are: two fluorocarbon compounds, two nitrile compounds, and a silicon compound. The materials were tested in a uniaxial compression test to determine the characteristic relaxation functions. These tests were performed at five different temperatures. A master material curve was developed for each material from the experimental data. The results of this study are compared to tensile relaxation tests. Application of these results to the design analysis is discussed in detail.

Calibration of silicone rubber rods as passive samplers for pesticides at two different flow velocities: Modeling of sampling rates under water boundary layer and polymer control.

PubMed

Martin, Alexis; Margoum, Christelle; Jolivet, Antoine; Assoumani, Azziz; El Moujahid, Bachir; Randon, Jérôme; Coquery, Marina

2018-04-01

There is a need to determine time-weighted average concentrations of polar contaminants such as pesticides by passive sampling in environmental waters. Calibration data for silicone rubber-based passive samplers are lacking for this class of compounds. The calibration data, sampling rate (R s ), and partition coefficient between silicone rubber and water (K sw ) were precisely determined for 23 pesticides and 13 candidate performance reference compounds (PRCs) in a laboratory calibration system over 14 d for 2 water flow velocities, 5 and 20 cm s -1 . The results showed that an in situ exposure duration of 7 d left a silicone rubber rod passive sampler configuration in the linear or curvilinear uptake period for 19 of the pesticides studied. A change in the transport mechanism from polymer control to water boundary layer control was observed for pesticides with a log K sw of approximately 3.3. The PRC candidates were not fully relevant to correct the impact of water flow velocity on R s . We therefore propose an alternative method based on an overall resistance to mass transfer model to adjust R s from laboratory experiments to in situ hydrodynamic conditions. We estimated diffusion coefficients (D s ) and thickness of water boundary layer (δ w ) as adjustable model parameters. Log D s values ranged from -12.13 to -10.07 m 2  s -1 . The estimated δ w value showed a power function correlation with water flow velocity. Environ Toxicol Chem 2018;37:1208-1218. © 2017 SETAC. © 2017 SETAC.

An investigation of industrial molding compounds for use in 3D ultrasound, MRI, and CT imaging phantoms

PubMed Central

Yunker, Bryan E.; Cordes, Dietmar; Scherzinger, Ann L.; Dodd, Gerald D.; Shandas, Robin; Feng, Yusheng; Hunter, Kendall S.

2013-01-01

Purpose: This study investigated the ultrasound, MRI, and CT imaging characteristics of several industrial casting and molding compounds as a precursor to the future development of durable and anatomically correct flow phantoms. Methods: A set of usability and performance criteria was established for a proposed phantom design capable of supporting liquid flow during imaging. A literature search was conducted to identify the materials and methods previously used in phantom fabrication. A database of human tissue and casting material properties was compiled to facilitate the selection of appropriate materials for testing. Several industrial casting materials were selected, procured, and used to fabricate test samples that were imaged with ultrasound, MRI, and CT. Results: Five silicones and one polyurethane were selected for testing. Samples of all materials were successfully fabricated. All imaging modalities were able to discriminate between the materials tested. Ultrasound testing showed that three of the silicones could be imaged to a depth of at least 2.5 cm (1 in.). The RP-6400 polyurethane exhibited excellent contrast and edge detail for MRI phantoms and appears to be an excellent water reference for CT applications. The 10T and 27T silicones appear to be usable water references for MRI imaging. Conclusions: Based on study data and the stated selection criteria, the P-4 silicone provided sufficient material contrast to water and edge detail for use across all imaging modalities with the benefits of availability, low cost, dimensional stability, nontoxic, nonflammable, durable, cleanable, and optical clarity. The physical and imaging differences of the materials documented in this study may be useful for other applications. PMID:23635298

Silane coupling agent bearing a photoremovable succinimidyl carbonate for patterning amines on glass and silicon surfaces with controlled surface densities.

PubMed

Nakayama, Hidekazu; Nakanishi, Jun; Shimizu, Takahiro; Yoshino, Yutaro; Iwai, Hideo; Kaneko, Shingo; Horiike, Yasuhiro; Yamaguchi, Kazuo

2010-03-01

Patterned immobilization of synthetic and biological ligands on material surfaces with controlled surface densities is important for various bioanalytical and cell biological purposes. This paper describes the synthesis, characterization, and application of a novel silane coupling agent bearing a photoremovable succinimidyl carbonate, which enables the photopatterning of various primary amines on glass and silicon surfaces. The silane coupling agent is 1-[5-methoxy-2-nitro-4-(3-trimethoxysilylpropyloxy)phenyl]ethyl N-succinimidyl carbonate. The distinct feature of this molecule is that it has a photocleavable 2-nitrobenzyl switch between a trimethoxysilyl group and a succinimidyl carbonate, each reactive to the hydroxy groups of inorganic oxides and primary amines. Based on this molecular design, the compound allows for the one-step introduction of succinimidyl carbonates onto the surface of glass and silicon, immobilization of primary amines, and region-selective and dose-dependent release of the amines by near-UV irradiation. Therefore, we were able to pattern amine ligands on the substrates in given surface densities and arbitrary geometries by controlling the doses and regions of photoirradiation. These features were verified by UV-vis spectroscopy, contact angle measurements, infrared (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), ellipsometry, and atomic force microscopy (AFM). The compound was applied to form a chemical density gradient of amino-biotin on a silicon substrate in a range of 0.87-0.12 chains/nm(2) by controlling photoirradiation under a standard fluorescence microscope. Furthermore, we also succeeded in forming a chemical density gradient at a lower surface density range (0.15-0.011 chains/nm(2)) on the substrate by diluting the feed amino-biotin with an inert control amine.

A new combined green method for 2-Chlorophenol removal using cross-linked Brassica rapa peroxidase in silicone oil.

PubMed

Tandjaoui, Nassima; Abouseoud, Mahmoud; Couvert, Annabelle; Amrane, Abdeltif; Tassist, Amina

2016-04-01

This study proposes a new technique to treat waste air containing 2-Chlorophenol (2-CP), namely an integrated process coupling absorption of the compound in an organic liquid phase and its enzymatic degradation. Silicone oil (47V20) was used as an organic absorbent to allow the volatile organic compound (VOC) transfer from the gas phase to the liquid phase followed by its degradation by means of Cross-linked Brassica rapa peroxidase (BRP) contained in the organic phase. An evaluation of silicone oil (47V20) absorption capacity towards 2-CP was first accomplished by determining its partition coefficient (H) in this solvent. The air-oil partition coefficient of 2-CP was found equal to 0.136 Pa m(3) mol(-1), which is five times lower than the air-water value (0.619 Pam(3) mol(-1)). The absorbed 2-CP was then subject to enzymatic degradation by cross-linked BRP aggregates (BRP-CLEAs). The degradation step was affected by four parameters (contact time; 2-CP, hydrogen peroxide and enzyme concentrations), which were optimized in order to obtain the highest conversion yield. A maximal conversion yield of 69% and a rate of 1.58 mg L(-1) min(-1)were obtained for 100 min duration time when 2-CP and hydrogen peroxide concentrations were respectively 80 mg L(-1) and 6 mM in the presence of 2.66 UI mL(-1) BRP-CLEAs. The reusability of BRP-CLEAs in silicone oil was assessed, showing promising results since 59% of their initial efficiency remained after three batches. Copyright © 2016 Elsevier Ltd. All rights reserved.

Mathematical model of silicon smelting process basing on pelletized charge from technogenic raw materials

NASA Astrophysics Data System (ADS)

Nemchinova, N. V.; Tyutrin, A. A.; Salov, V. M.

2018-03-01

The silicon production process in the electric arc reduction furnaces (EAF) is studied using pelletized charge as an additive to the standard on the basis of the generated mathematical model. The results obtained due to the model will contribute to the analysis of the charge components behavior during melting with the achievement of optimum final parameters of the silicon production process. The authors proposed using technogenic waste as a raw material for the silicon production in a pelletized form using liquid glass and aluminum production dust from the electrostatic precipitators as a binder. The method of mathematical modeling with the help of the ‘Selector’ software package was used as a basis for the theoretical study. A model was simulated with the imitation of four furnace temperature zones and a crystalline silicon phase (25 °C). The main advantage of the created model is the ability to analyze the behavior of all burden materials (including pelletized charge) in the carbothermic process. The behavior analysis is based on the thermodynamic probability data of the burden materials interactions in the carbothermic process. The model accounts for 17 elements entering the furnace with raw materials, electrodes and air. The silicon melt, obtained by the modeling, contained 91.73 % wt. of the target product. The simulation results showed that in the use of the proposed combined charge, the recovery of silicon reached 69.248 %, which is in good agreement with practical data. The results of the crystalline silicon chemical composition modeling are compared with the real silicon samples of chemical analysis data, which showed the results of convergence. The efficiency of the mathematical modeling methods in the studying of the carbothermal silicon obtaining process with complex interphase transformations and the formation of numerous intermediate compounds using a pelletized charge as an additive to the traditional one is shown.

Molybdenum disilicide matrix composite

DOEpatents

Petrovic, John J.; Carter, David H.; Gac, Frank D.

1991-01-01

A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

Molybdenum disilicide matrix composite

DOEpatents

Petrovic, John J.; Carter, David H.; Gac, Frank D.

1990-01-01

A composition consisting of an intermetallic compound, molybdenum disilicide, which is reinforced with VS silicon carbide whiskers dispersed throughout it and a method of making the reinforced composition. Use of the reinforcing material increases fracture toughness at low temperatures and strength at high temperatures, as compared to pure molybdenum disilicide.

High resolution and sensitivity infrared tomography

NASA Astrophysics Data System (ADS)

Fillard, J. P.; Montgomery, P. C.; Gall, P.; Castagné, M.; Bonnafé, J.

1990-06-01

Laser scanning tomography was proposed some years ago by Ogawa and coworkers as a qualification test for semiconductor materials. From that time on, this technique has been used profitably to obtain images of internal defect distributions in III-V compounds as well as in II-VI compounds or even in silicon. These images especially reveal micro precipitates (e.g. decorated dislocations) distributed in the volume of the bulk material. Previously images sale were adapted to wafer examination (centimeter scale) but it appeared later that a major interest was to improve the resolution down to the microscopical range in order to investigate smaller zones and, above all, thinner sections. Nevertheless there is a limitation in the range of 10 μm for the minimum thickness of LST planes and this drawback prevents the using of this technique in the analysis of thin epilayers or structures. In this paper the emphasis is put on the fundamental and practical limits of the resolution, contrast and detectivity. Special optical arrangements will be suggested to reach the best specifications. Other possible dark field scattering tomographical microscopy methods have been evaluated and will be comparatively discussed in the light of preliminary results. Typical results relative to III-V compounds as well as silicon will be presented and quantitative specifications of the methods will be compared.

Formation of equiaxed crystal structures in directionally solidified Al-Si alloys using Nb-based heterogeneous nuclei

PubMed Central

Bolzoni, Leandro; Xia, Mingxu; Babu, Nadendla Hari

2016-01-01

The design of chemical compositions containing potent nuclei for the enhancement of heterogeneous nucleation in aluminium, especially cast alloys such as Al-Si alloys, is a matter of importance in order to achieve homogeneous properties in castings with complex geometries. We identified that Al3Nb/NbB2 compounds are effective heterogeneous nuclei and are successfully produced in the form of Al-2Nb-xB (x = 0.5, 1 and 2) master alloys. Our study shows that the inoculation of Al-10Si braze alloy with these compounds effectively promotes the heterogeneous nucleation of primary α-Al crystals and reduces the undercooling needed for solidification to take place. Moreover, we present evidences that these Nb-based compounds prevent the growth of columnar crystals and permit to obtain, for the first time, fine and equiaxed crystals in directionally solidified Al-10Si braze alloy. As a consequence of the potent heterogeneous particles, the size of the α-Al crystals was found to be less dependent on the processing conditions, especially the thermal gradient. Finally, we also demonstrate that the enhanced nucleation leads to the refinement of secondary phases such as eutectic silicon and primary silicon particles. PMID:28008967

The effect of axial ligands on the quantum yield of singlet oxygen of new silicon phthalocyanine

NASA Astrophysics Data System (ADS)

Lv, Huafei; Zhang, Xuemei; Yu, Xinxin; Pan, Sujuan; Xie, Shusen; Yang, Hongqin; Peng, Yiru

2016-10-01

The singlet oxygen (1O2) production abilitity is an important factor to assess their potential as effective of photosensitizers. In this paper, the 1O2 production rate, production rate constant and quantum yield of silicon(IV) phthalocyanine axially bearing 1-3 generation dendritic substituents were evaluated by a high performance liquid chromatographic method. The results show that the 1O2 production rate and production rate constant of these compounds increase gradually with dendritic generations increase. And the 1O2 quantum yield of silicon(IV) phthalocyanine with first generation dendritic ligand was the highest. This may be due to the isolation effect of the dendritic ligands on the phthalocyanine core. The parameters of the observed 1O2 production properties will provide valuable data for these dendrimer phthalocyanines as promising photosensitizer in PDT application.

Application of pyroelectric crystal and ionic liquid to the production of metal compounds

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

Imashuku, Susumu; Imanishi, Akira; Kawai, Jun

2013-04-19

Zinc fluoride (ZnF{sub 2}) was deposited on a silicon substrate by changing temperature of a pyroelectric crystal of LiTaO{sub 3} on which ionic liquid (EMI-Tf{sub 2}N) containing zinc ions was dripped at 1 Pa. ZnF{sub 2} was also obtained by bombarding argon ions on EMI-Tf{sub 2}N containing zinc ions. From these results, it is concluded that EMI-Tf{sub 2}N containing zinc ions on the LiTaO{sub 3} crystal was evaporated on the silicon substrate by changing temperature of the LiTaO{sub 3} crystal in vacuum and that the evaporated EMI-Tf{sub 2}N containing metal zinc ions was decomposed to ZnF{sub 2} by the bombardmentmore » of electrons accelerated by the electric field between the LiTaO{sub 3} crystal and the silicon substrate.« less

Method of processing aluminous ores

DOEpatents

Loutfy, Raouf O.; Keller, Rudolf; Yao, Neng-Ping

1981-01-01

A method of producing aluminum chloride from aluminous materials containing compounds of iron, titanium and silicon comprising reacting the aluminous materials with carbon and a chlorine-containing gas at a temperature of about 900.degree. K. to form a gaseous mixture containing chlorides of aluminum, iron, titanium and silicon and oxides of carbon; cooling the gaseous mixture to a temperature of about 400.degree. K. or lower to condense the aluminum chlorides and iron chlorides while titanium chloride and silicon chloride remain in the gas phase to effect a separation thereof; heating the mixture of iron chlorides and aluminum chlorides to a temperature of about 800.degree. K. to form gaseous aluminum chlorides and iron chlorides; passing the heated gases into intimate contact with aluminum sulfide to precipitate solid iron sulfide and to form additional gaseous aluminum chlorides; and separating the gaseous aluminum chloride from the solid iron sulfide.

Origami silicon optoelectronics for hemispherical electronic eye systems.

PubMed

Zhang, Kan; Jung, Yei Hwan; Mikael, Solomon; Seo, Jung-Hun; Kim, Munho; Mi, Hongyi; Zhou, Han; Xia, Zhenyang; Zhou, Weidong; Gong, Shaoqin; Ma, Zhenqiang

2017-11-24

Digital image sensors in hemispherical geometries offer unique imaging advantages over their planar counterparts, such as wide field of view and low aberrations. Deforming miniature semiconductor-based sensors with high-spatial resolution into such format is challenging. Here we report a simple origami approach for fabricating single-crystalline silicon-based focal plane arrays and artificial compound eyes that have hemisphere-like structures. Convex isogonal polyhedral concepts allow certain combinations of polygons to fold into spherical formats. Using each polygon block as a sensor pixel, the silicon-based devices are shaped into maps of truncated icosahedron and fabricated on flexible sheets and further folded either into a concave or convex hemisphere. These two electronic eye prototypes represent simple and low-cost methods as well as flexible optimization parameters in terms of pixel density and design. Results demonstrated in this work combined with miniature size and simplicity of the design establish practical technology for integration with conventional electronic devices.

Large-Area Direct Hetero-Epitaxial Growth of 1550-nm InGaAsP Multi-Quantum-Well Structures on Patterned Exact-Oriented (001) Silicon Substrates by Metal Organic Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Megalini, Ludovico; Cabinian, Brian C.; Zhao, Hongwei; Oakley, Douglas C.; Bowers, John E.; Klamkin, Jonathan

2018-02-01

We employ a simple two-step growth technique to grow large-area 1550-nm laser structures by direct hetero-epitaxy of III-V compounds on patterned exact-oriented (001) silicon (Si) substrates by metal organic chemical vapor deposition. Densely-packed, highly uniform, flat and millimeter-long indium phosphide (InP) nanowires were grown from Si v-grooves separated by silicon dioxide (SiO2) stripes with various widths and pitches. Following removal of the SiO2 patterns, the InP nanowires were coalesced and, subsequently, 1550-nm laser structures were grown in a single overgrowth without performing any polishing for planarization. X-ray diffraction, photoluminescence, atomic force microscopy and transmission electron microscopy analyses were used to characterize the epitaxial material. PIN diodes were fabricated and diode-rectifying behavior was observed.

Nonlinear conductivity in silicon nitride

NASA Astrophysics Data System (ADS)

Tuncer, Enis

2017-08-01

To better comprehend electrical silicon-package interaction in high voltage applications requires full characterization of the electrical properties of dielectric materials employed in wafer and package level design. Not only the packaging but wafer level dielectrics, i.e. passivation layers, would experience high electric fields generated by the voltage applied pads. In addition the interface between the passivation layer and a mold compound might develop space charge because of the mismatch in electrical properties of the materials. In this contribution electrical properties of a thin silicon nitride (Si3N4) dielectric is reported as a function of temperature and electric field. The measured values later analyzed using different temperature dependent exponential expressions and found that the Mott variable range hopping conduction model was successful to express the data. A full temperature/electric field dependency of conductivity is generated. It was found that the conduction in Si3N4 could be expressed like a field ionization or Fowler-Nordheim mechanism.

Liquid- and solid-state high-resolution NMR methods for the investigation of aging processes of silicone breast implants.

PubMed

Birkefeld, Anja Britta; Bertermann, Rüdiger; Eckert, Hellmut; Pfleiderer, Bettina

2003-01-01

To investigate aging processes of silicone gel breast implants, which may include migration of free unreacted material from the gel and rubber to local (e.g. connective tissue capsule) or distant sites in the body, chemical alteration of the polymer and infiltration of body compounds, various approaches of multinuclear nuclear magnetic resonance (NMR) experiments (29Si, 13C, 1H) were evaluated. While 29Si, 13C, and 1H solid-state magic angle spinning (MAS) NMR techniques performed on virgin and explanted envelopes of silicone prostheses provided only limited information, high-resolution liquid-state NMR techniques of CDCl(3) extracts were highly sensitive analytical tools for the detection of aging related changes in the materials. Using 2D 1H, 1H correlation spectroscopy (COSY) and 29Si, 1H heteronuclear multiple bond coherence (HMBC) experiments with gradient selection, it was possible to detect lipids (mainly phospholipids) as well as silicone oligomer species in explanted envelopes and gels. Silicone oligomers were also found in connective tissue capsules, indicating that cyclic polysiloxanes can migrate from intact implants to adjacent and distant sites. Furthermore, lipids can permeate the implant and modify its chemical composition. Copyright 2002 Elsevier Science Ltd.

Tribological Characteristics of Submicron SiC(p)-GR(p)/Zn-35Al-1Mg Composites in Semisolidification Casting process

NASA Astrophysics Data System (ADS)

Liu, S.; Fang, Z. W.; Li, L. X.

2018-05-01

Uniform SiC(p)-GR(p)/Zn-35Al-1Mg composites were prepared by powder pressing and semisolidification stirring-casting process by adding submicron silicon carbide and graphite reinforcement particles in an aluminum-zinc alloy matrix. Micro Vickers hardness and microstructures of the novel composites were studied, and their wear properties and wear temperature were measured for different load and friction conditions. The results show that silicon carbide and graphite particles homogeneously mix in the matrix, while contained silicon carbide particles improve the matrix hardness to 8.4%, graphite improves the matrix hardness to 16.8%, but two of them, combined, reduce the matrix hardness to 7.6%; the rate of temperature rise of the zinc-aluminum matrix alloy is the highest than the other three composites and is up to 48.5° C/s at 1.69MPa. At 0.56MPa and sliding 26.4km, the graphite composite anti-wear effect is optimal, while at 1.13MPa, the wear resistance of silicon carbide and graphite compound particles is the best; in the other case of only silicon carbide particles, the wear resistance is increased to 35% at 1.69MPa and 26.4km, and its anti-wear effects are excellent.

Reactions of Persistent Carbenes with Hydrogen-Terminated Silicon Surfaces.

PubMed

Zhukhovitskiy, Aleksandr V; Mavros, Michael G; Queeney, K T; Wu, Tony; Voorhis, Troy Van; Johnson, Jeremiah A

2016-07-13

Surface passivation has enabled the development of silicon-based solar cells and microelectronics. However, a number of emerging applications require a paradigm shift from passivation to functionalization, wherein surface functionality is installed proximal to the silicon surface. To address this need, we report here the use of persistent aminocarbenes to functionalize hydrogen-terminated silicon surfaces via Si-H insertion reactions. Through the use of model compounds (H-Si(TMS)3 and H-Si(OTMS)3), nanoparticles (H-SiNPs), and planar Si(111) wafers (H-Si(111)), we demonstrate that among different classes of persistent carbenes, the more electrophilic and nucleophilic ones, in particular, a cyclic (alkyl)(amino)carbene (CAAC) and an acyclic diaminocarbene (ADAC), are able to undergo insertion into Si-H bonds at the silicon surface, forming persistent C-Si linkages and simultaneously installing amine or aminal functionality in proximity to the surface. The CAAC (6) is particularly notable for its clean insertion reactivity under mild conditions that produces monolayers with 21 ± 3% coverage of Si(111) atop sites, commensurate with the expected maximum of ∼20%. Atomic force and transmission electron microscopy, nuclear magnetic resonance, X-ray photoelectron, and infrared spectroscopy, and time-of-flight secondary ion mass spectrometry provided evidence for the surface Si-H insertion process. Furthermore, computational studies shed light on the reaction energetics and indicated that CAAC 6 should be particularly effective at binding to silicon dihydride, trihydride, and coupled monohyride motifs, as well as oxidized surface sites. Our results pave the way for the further development of persistent carbenes as universal ligands for silicon and potentially other nonmetallic substrates.

Reaction cured glass and glass coatings

NASA Technical Reports Server (NTRS)

Goldstein, H. E.; Leiser, D. B.; Katvala, V. W. (Inventor)

1978-01-01

The invention relates to reaction cured glass and glass coatings prepared by reacting a compound selected from the group consisting of silicon tetraboride, silicon hexaboride, other boron silicides, boron and mixtures with a reactive glass frit composed of a porous high silica borosilicate glass and boron oxide. The glassy composites of the present invention are useful as coatings on low density fibrous porous silica insulations used as heat shields and for articles such as reaction vessels that are subjected to high temperatures with rapid heating and cooling and that require resistance to temperature and repeated thermal shock at temperatures up to about 1482C (2700PF).

Sandblasting nozzle

NASA Technical Reports Server (NTRS)

Perkins, G. S.; Pawlik, E. V.; Phillips, W. M. (Inventor)

1981-01-01

A nozzle for use with abrasive and/or corrosive materials is formed of sintered ceramic compositions having high temperature oxidation resistance, high hardness and high abrasion and corrosion resistance. The ceramic may be a binary solid solution of a ceramic oxide and silicon nitride, and preferably a ternary solid solution of a ceramic oxide, silicon nitride and aluminum nitride. The ceramic oxide is selected from a group consisting of Al2O3, Y2O3 and Cr2O3, or mixtures of those compounds. Titanium carbide particles are dispersed in the ceramic mixture before sintering. The nozzles are encased for protection from external forces while in use by a metal or plastic casing.

Method for extracting metals from aqueous waste streams for long term storage

DOEpatents

Chaiko, D.J.

1995-03-07

A liquid-liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average individual particle sizes of approximately 40 nanometers. 2 figs.

Method for extracting metals from aqueous waste streams for long term storage

DOEpatents

Chaiko, D.J.

1993-01-01

A liquid-liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average. individual particle sizes of approximately 40 manometers.

Method for extracting metals from aqueous waste streams for long term storage

DOEpatents

Chaiko, David J.

1995-01-01

A liquid--liquid extraction method for removing metals and hydrous metal colloids from waste streams is provided wherein said waste streams are contacted with a solvent system containing a water-in-oil microemulsion wherein the inverted micelles contain the extracted metal. A silicon alkoxide, either alone or in combination with other metal alkoxide compounds is added to the water-in-oil microemulsion, thereby allowing encapsulation of the extracted metal within a silicon oxide network. Lastly, the now-encapsulated metal is precipitated from the water-in-oil microemulsion phase to yield aggregates of metal-silicate particles having average individual particle sizes of approximately 40 nanometers.

A silicon micromachined resonant pressure sensor

NASA Astrophysics Data System (ADS)

Tang, Zhangyang; Fan, Shangchun; Cai, Chenguang

2009-09-01

This paper describes the design, fabrication and test of a silicon micromachined resonant pressure sensor. A square membrane and a doubly clamped resonant beam constitute a compound structure. The former senses the pressure directly, while the latter changes its resonant frequency according to deformation of the membrane. The final output relation between the resonant frequency and the applied pressure is deducted according to the structure mechanical properties. Sensors are fabricated by micromachining technology, and then sealed in vaccum. These sensors are tested by open-loop and close-loop system designed on purpose. The experiment results demonstrate that the sensor has a sensitivity of 49.8Hz/kPa and repeatability of 0.08%.

Boron nitride - Composition, optical properties, and mechanical behavior

NASA Technical Reports Server (NTRS)

Pouch, John J.; Alterovitz, Samuel A.; Miyoshi, Kazuhisa; Warner, Joseph D.

1987-01-01

A low energy ion beam deposition technique was used to grow boron nitride films on quartz, germanium, silicon, gallium arsenide, and indium phosphate. The film structure was amorphous with evidence of a hexagonal phase. The peak boron concentration was 82 at. percent. The carbon and oxygen impurities were in the 5 to 8 at. percent range. Boron-nitrogen and boron-boron bonds were revealed by X-ray photoelectron spectroscopy. The index of refraction varied from 1.65 to 1.67 for films deposited on III-V compound semiconductors. The coefficient of friction for boron nitride in sliding contact with diamond was less than 0.1. The substrate was silicon.

Boron nitride: Composition, optical properties and mechanical behavior

NASA Technical Reports Server (NTRS)

Pouch, John J.; Alterovitz, Samuel A.; Miyoshi, Kazuhisa; Warner, Joseph D.

1987-01-01

A low energy ion beam deposition technique was used to grow boron nitride films on quartz, germanium, silicon, gallium arsenide, and indium phosphate. The film structure was amorphous with evidence of a hexagonal phase. The peak boron concentration was 82 at %. The carbon and oxygen impurities were in the 5 to 8 at % range. Boron-nitrogen and boron-boron bonds were revealed by X-ray photoelectron spectroscopy. The index of refraction varied from 1.65 to 1.67 for films deposited on III-V compound semiconductors. The coefficient of friction for boron nitride in sliding contact with diamond was less than 0.1. The substrate was silicon.

MEMBRANE-MODERATED STRIPPING PROCESS FOR REMOVING VOCS FROM WATER IN A COMPOSITE HOLLOW FIBER MODULE. (R825511C027)

EPA Science Inventory

The "stripmeation" process for removing volatile organic compounds (VOCs) from water has been introduced and studied. An aqueous solution of the VOC is passed through the bores of hydrophobic microporous polypropylene hollow fibers having a plasma polymerized silicone ...

Red Phosphorus for Use in Screening Smoke Compositions

DTIC Science & Technology

1999-02-01

weight % paraffin oil, or mineral oil, or silicon oil, or 20 to 50 weight % pentaerithritol based on the nitrogen compound. Kaiser and Cadus (BASF)27...impregnated red phosphorus. Kaiser O and Cadus A BASF AG US 3,951,908 (1974) III References 28 Desensitised free-flowing red phosphorus. Wortmann J

Molding Compound For Inspection Of Internal Contours

NASA Technical Reports Server (NTRS)

Adams, Jim; Ricklefs, Steve

1988-01-01

Material clean, sets rapidly, and easy to use. Silicone elastomer, Citrocon or equivalent, commonly used in dentistry, in combination with mold-release agent (Also see MFS-29240), speeds and facilitates making of impressions of interior surfaces so surface contours examined. Elastomer easily moved around in cavity until required location found.

The Effect of Fermentation Broth Components on Performance of High Silica ZSM-5/Silicone Rubber Mixed Matrix Membranes

EPA Science Inventory

Fermentative organisms produce a range of compounds in addition to the desired product. For example, in addition to ethanol, standard yeast produces longer straight-chained and branched alcohols and organic acids. Additionally, biomass pretreatment process, particularly acid-base...

Metalloid compounds as drugs

PubMed Central

Sekhon, B. S.

2013-01-01

The six elements commonly known as metalloids are boron, silicon, germanium, arsenic, antimony, and tellurium. Metalloid containing compounds have been used as antiprotozoal drugs. Boron-based drugs, the benzoxaboroles have been exploited as potential treatments for neglected tropical diseases. Arsenic has been used as a medicinal agent and arsphenamine was the main drug used to treat syphilis. Arsenic trioxide has been approved for the treatment of acute promyelocytic leukemia. Pentavalent antimonials have been the recommended drug for visceral leishmaniasis and cutaneous leishmaniasis. Tellurium (IV) compounds may have important roles in thiol redox biological activity in the human body, and ammonium trichloro (dioxoethylene-O, O’-)tellurate (AS101) may be a promising agent for the treatment of Parkinson’s disease. Organosilicon compounds have been shown to be effective in vitro multidrug-resistance reverting agents. PMID:24019824

Chemical vapor deposition and characterization of polysilanes polymer based thin films and their applications in compound semiconductors and silicon devices

NASA Astrophysics Data System (ADS)

Oulachgar, El Hassane

As the semiconductors industry is moving toward nanodevices, there is growing need to develop new materials and thin films deposition processes which could enable strict control of the atomic composition and structure of thin film materials in order to achieve precise control on their electrical and optical properties. The accurate control of thin film characteristics will become increasingly important as the miniaturization of semiconductor devices continue. There is no doubt that chemical synthesis of new materials and their self assembly will play a major role in the design and fabrication of next generation semiconductor devices. The objective of this work is to investigate the chemical vapor deposition (CVD) process of thin film using a polymeric precursor as a source material. This process offers many advantages including low deposition cost, hazard free working environment, and most importantly the ability to customize the polymer source material through polymer synthesis and polymer functionalization. The combination between polymer synthesis and CVD process will enable the design of new generation of complex thin film materials with a wide range of improved chemical, mechanical, electrical and optical properties which cannot be easily achieved through conventional CVD processes based on gases and small molecule precursors. In this thesis we mainly focused on polysilanes polymers and more specifically poly(dimethylsilanes). The interest in these polymers is motivated by their distinctive electronic and photonic properties which are attributed to the delocalization of the sigma-electron along the Si-Si backbone chain. These characteristics make polysilane polymers very promising in a broad range of applications as a dielectric, a semiconductor and a conductor. The polymer-based CVD process could be eventually extended to other polymer source materials such as polygermanes, as well as and a variety of other inorganic and hybrid organic-inorganic polymers. This work has demonstrated that a polysilane polymeric source can be used to deposit a wide range of thin film materials exhibiting similar properties with conventional ceramic materials such as silicon carbide (SiC), silicon oxynitride (SiON), silicon oxycarbide (SiOC) silicon dioxide (SiO2) and silicon nitride (Si3N4). The strict control of the deposition process allows precise control of the electrical, optical and chemical properties of polymer-based thin films within a broad range. This work has also demonstrated for the first time that poly(dimethylsilmaes) polymers deposited by CVD can be used to effectively passivate both silicon and gallium arsenide MOS devices. This finding makes polymer-based thin films obtained by CVD very promising for the development of high-kappa dielectric materials for next generation high-mobility CMOS technology. Keywords. Thin films, Polymers, Vapor Phase Deposition, CVD, Nanodielectrics, Organosilanes, Polysilanes, GaAs Passivation, MOSFET, Silicon Oxynitride, Integrated Waveguide, Silicon Carbide, Compound Semiconductors.

Discovery and Identification of Dimethylsilanediol as a Contaminant in ISS Potable Water

NASA Technical Reports Server (NTRS)

Rutz, Jeffrey A.; Schultz, John R.; Kuo, C. Mike; Curtis, Matthew; Jones, Patrick R.; Sparkman, O. David; McCoy, J. Torin

2011-01-01

In September 2010, analysis of ISS potable water samples was undertaken to determine the contaminant(s) responsible for a rise of total organic carbon (TOC) in the Water Processor Assembly (WPA) product water. As analysis of the routine target list of organic compounds did not reveal the contaminant, efforts to look for unknown compounds were initiated, resulting in discovery of an unknown peak in the gas chromatography/mass spectrometry (GC/MS) analysis for glycols. A mass spectrum of the contaminant was then generated by concentrating one of the samples and analyzing it by GC/MS in full-scan mode. Although a computer match of the compound identity could not be obtained with the instrument database, a search with a more up-to-date mass spectral library yielded a good match with dimethylsilanediol (DMSD). Inductively coupled plasma/mass spectrometry (ICP/MS) analyses showed abnormally high silicon levels in the samples, confirming that the unknown compound(s) contained silicon. DMSD was then synthesized to confirm the identification and provide a standard to develop a calibration curve. Further confirmation was provided by external direct analysis in real time time of flight (DART TOF) mass spectrometry. To routinely test for DMSD in the future, a quantitative method was needed. A preliminary GC/MS method was developed and archived samples from various locations on ISS were analyzed to determine the extent of the contamination and provide data for troubleshooting. This paper describes these events in more detail as well as problems encountered in routine GC/MS analyses and the subsequent development of high performance liquid chromatography and LC/MS/MS methods for measuring DMSD.

Emergence of two lamellas during impact of compound droplets

NASA Astrophysics Data System (ADS)

Liu, Dongdong; Tran, Tuan

2018-05-01

A compound droplet consisting of water and silicone oil either spreads or splashes upon impacting a solid surface. We show that the transition from spreading to splashing of this type of compound droplet can be changed by varying the volumetric oil ratio in the droplets. In the spreading regime, we observe a surprising emergence of two lamellas spreading one after the other: the first spreading lamella consists of only oil and the trailing one water. We show that the two lamellas eventually meet, significantly affecting the spreading dynamics. Finally, we quantify the maximum spreading radius and show that it is a function of both the impact velocity and the volumetric oil ratio.

Electrolytic photodissociation of chemical compounds by iron oxide electrodes

DOEpatents

Somorjai, Gabor A.; Leygraf, Christofer H.

1984-01-01

Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor diode having visible light as its sole source of energy. The diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

Electrolytic photodissociation of chemical compounds by iron oxide photochemical diodes

DOEpatents

Somorjai, Gabor A.; Leygraf, Christofer H.

1985-01-01

Chemical compounds can be dissociated by contacting the same with a p/n type semi-conductor photochemical diode having visible light as its sole source of energy. The photochemical diode consists of low cost, readily available materials, specifically polycrystalline iron oxide doped with silicon in the case of the n-type semi-conductor electrode, and polycrystalline iron oxide doped with magnesium in the case of the p-type electrode. So long as the light source has an energy greater than 2.2 electron volts, no added energy source is needed to achieve dissociation.

Effects of various additives on sintering of aluminum nitride

NASA Technical Reports Server (NTRS)

Komeya, K.; Inoue, H.; Tsuge, A.

1982-01-01

Effects of thirty additives on sintering A/N were investigated. The addition of alkali earth oxides and rare earth oxides gave fully densified aluminum nitride. This is due to the formation of nitrogen-containing aluminate liquid in the system aluminum nitride-alkali earth oxides or rare earth oxides. Microstructural studies of the sintered specimens with the above two types of additives suggested that the densification was due to the liquid phase sintering. Additions of silicon compounds resulted in poor densification by the formation of highly refractory compounds such as A/N polytypes.

USING ACID-RESISTANT PHOTOSENSITIVE EMULSIONS TO OBTAIN LOCAL INHOMOGENEITIES WITH A HIGH RESOLVING POWER ON MONOCRYSTALS AND FILMS OF GERMANIUM AND SILICON (PRIMENENIE KISLOTOSTOYKHIKH SVETOCHUVSTVITELNYKH EMULSII DLYA POLUCHENIYA LOKALNYKH NEODNORODNOSTEI S VYSOKIM RAZRESHENIEM NA MONOKRISTALLAKH I PLENKAKH GERMANIYA I KREMNIYA),

DTIC Science & Technology

It was found that the esters of polystyrene and cinnamic acid , polyvinyl alcohol, and cinnamic acid have high dielectric characteristics that change...Photosensitive acid -resisting emulsions for use in photoengraving of semiconductor parts and semiconductor surfaces were synthesized and tested...organosilicon compounds, cinnamic aldehyde, emulsions based on azo and diazo compounds and polymeric polyesters--were tested. The photoengraving method

Alkoxide-based magnesium electrolyte compositions for magnesium batteries

DOEpatents

Dai, Sheng; Sun, Xiao-Guang; Liao, Chen; Guo, Bingkun

2018-01-30

Alkoxide magnesium halide compounds having the formula: RO--Mg--X (1) wherein R is a saturated or unsaturated hydrocarbon group that is unsubstituted, or alternatively, substituted with one or more heteroatom linkers and/or one or more heteroatom-containing groups comprising at least one heteroatom selected from fluorine, nitrogen, oxygen, sulfur, and silicon; and X is a halide atom. Also described are electrolyte compositions containing a compound of Formula (1) in a suitable polar aprotic or ionic solvent, as well as magnesium batteries in which such electrolytes are incorporated.

Thin-Film Photovoltaics: Status and Applications to Space Power

NASA Technical Reports Server (NTRS)

Landis, Geoffrey A.; Hepp, Aloysius F.

1991-01-01

The potential applications of thin film polycrystalline and amorphous cells for space are discussed. There have been great advances in thin film solar cells for terrestrial applications; transfer of this technology to space applications could result in ultra low weight solar arrays with potentially large gains in specific power. Recent advances in thin film solar cells are reviewed, including polycrystalline copper iridium selenide and related I-III-VI2 compounds, polycrystalline cadmium telluride and related II-VI compounds, and amorphous silicon alloys. The possibility of thin film multi bandgap cascade solar cells is discussed.

Beyond alkyl transfer: Synthesis of main group metal (Mg, Ca, Zn) silyl and tris(oxazolinyl)borato complexes and their stoichiometric and catalytic reactions with borane Lewis acids and carbonyls

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

Lampland, Nicole Lynn

2015-05-09

Recently, the fundamental knowledge of main group metal chemistry has grown. This progress is crucial for the further development of main group metal compounds in silicon chemistry and catalysis and for advancing their applications as green alternatives to many rare earth and transition metal compounds. This thesis focuses on reactivity beyond the welldocumented alkyl-transfer applications for main group metals, and it highlights examples of reactions with Lewis acids and the reduction of carbonyls.

Crystal structures of bis-(phen-oxy)silicon phthalocyanines: increasing π-π inter-actions, solubility and disorder and no halogen bonding observed.

PubMed

Lessard, Benoît H; Lough, Alan J; Bender, Timothy P

2016-07-01

We report the syntheses and characterization of three solution-processable phen-oxy silicon phthalocyanines (SiPcs), namely bis-(3-methyl-phen-oxy)(phthalocyanine)silicon [(3MP)2-SiPc], C46H30N8O2Si, bis-(2-sec-butyl-phen-oxy)(phthalocyanine)silicon [(2secBP)2-SiPc], C44H24I2N8O2Si, and bis-(3-iodo-phen-oxy)(phthalocyanine)silicon [(3IP)2-SiPc], C52H42N8O2Si. Crystals grown of these compounds were characterized by single-crystal X-ray diffraction and the π-π inter-actions between the aromatic SiPc cores were studied. It was determined that (3MP)2-SiPc has similar inter-actions to previously reported bis-(3,4,5-tri-fluoro-phen-oxy)silicon phthalocyanines [(345 F)2-SiPc] with significant π-π inter-actions between the SiPc groups. (3IP)2-SiPc and (2secBP)2-SiPc both experienced a parallel stacking of two of the peripheral aromatic groups. In all three cases, the solubility of these mol-ecules was increased by the addition of phen-oxy groups while maintaining π-π inter-actions between the aromatic SiPc groups. The solubility of (2secBP)2-SiPc was significantly higher than other bis-phen-oxy-SiPcs and this was exemplified by the higher observed disorder within the crystal structure.

Surface morphology of molybdenum silicide films upon low-energy ion beam sputtering.

PubMed

Gago, R; Jaafar, M; Palomares, F J

2018-07-04

The surface morphology of molybdenum silicide (Mo x Si 1-x ) films has been studied after low-energy Ar + ion beam sputtering (IBS) to explore eventual pattern formation on compound targets and, simultaneously, gather information about the mechanisms behind silicide-assisted nanopatterning of silicon surfaces by IBS. For this purpose, Mo x Si 1-x films with compositions below, equal and above the MoSi 2 stoichiometry (x  =  0.33) have been produced by magnetron sputtering, as assessed by Rutherford backscattering spectrometry (RBS). The surface morphology of silicon and silicide films before and after IBS has been imaged by atomic force microscopy (AFM), comprising conditions where typical nanodot or ripple patterns emerge on the former. In the case of irradiated Mo x Si 1-x surfaces, AFM shows a marked surface smoothing at normal incidence with and without additional Mo incorporation (the former results in nanodot patterns on Si). The morphological analysis also provides no evidence of ion-induced phase separation in irradiated Mo x Si 1-x . Contrary to silicon, Mo x Si 1-x surfaces also do not display ripple formation for (impurity free) oblique irradiations, except at grazing incidence conditions where parallel ripples emerge in a more evident fashion than in the Si counterpart. By means of RBS, irradiated Mo x Si 1-x films with 1 keV Ar + at normal incidence have also been used to measure experimentally the (absolute) sputtering yield and rate of Si and Mo x Si 1-x materials. The analysis reveals that, under the present working conditions, the erosion rate of silicides is larger than for silicon, supporting simulations from the TRIDYN code. This finding questions the shielding effect from silicide regions as roughening mechanism in metal-assisted nanopatterning of silicon. On the contrary, the results highlight the relevance of in situ silicide formation. Ripple formation on Mo x Si 1-x under grazing incidence is also attributed to the dominance of sputtering effects under this geometry. In conclusion, our work provides some insights into the complex morphological evolution of compound surfaces and solid experimental evidences regarding the mechanisms behind silicide-assisted nanopatterning.

Aerosol chemical vapor deposition of metal oxide films

DOEpatents

Ott, K.C.; Kodas, T.T.

1994-01-11

A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said substrate.

COMPARISON OF TRICHLOROETHYLENE REDUCTIVE DEHALOGENATION BY MICROBIAL COMMUNITIES STIMULATED ON SILICON-BASED ORGANIC COMPOUNDS AS SLOW-RELEASE ANAEROBIC SUBSTRATES. (R828772C001)

EPA Science Inventory

Microcosm studies were conducted to demonstrate the effectiveness of tetrabutoxysilane (TBOS) as a slow-release anaerobic substrate to promote reductive dehalogenation of trichloroethylene (TCE). The abiotic hydrolysis of TBOS and tetrakis(2-ethylbutoxy)silane (TKEBS), and the...

Crack-resistant siloxane molding compounds. [Patent application

DOEpatents

McFarland, J.W.; Swearngin, C.B.

1980-11-03

The crack resistance of phenyl silicone molding resins containing siliceous fillers is improved by incorporating therein about 0.5 to 5.5% by weight of ..beta..-eucryptite, a lithium aluminum silicate having a negative thermal expansion coefficient. These molding resins are particularly suitable for encapsulating electronic devices such as diodes, coils, resistors, and the like.

A STUDY OF HIGH MODULUS, HIGH STRENGTH FILAMENT MATERIALS BY DEPOSITION TECHNIQUES.

DTIC Science & Technology

had an average tensile strength of 240000 psi. The x-ray spectra of silicon carbide filaments made from SiCl4 , trichlorosilane, and...trichloromethylsilane were compared. The filaments produced from the two silane compounds showed strong peaks of SiC whereas the spectra for the SiCl4 produced

Transmission electron microscopy: direct observation of crystal structure in refractory ceramics.

PubMed

Shaw, T M; Thomas, G

1978-11-10

Using high-resolution multibeam interference techniques in the transmission electron microscope, images have been obtained that make possible a real-space structure analysis of a beryllium-silicon-nitrogen compound. The results illustrate the usefulness of lattice imaging in the analysis of local crystal structure in these technologically promising ceramic materials.

Design and Development of Peptides from the Anti-Angiogenic Pigment Epithelial-Derived Factor for the Therapy of Prostate Cancer

DTIC Science & Technology

2006-12-01

to perform, but also re- quire substantial amounts of test compound and most rely on selective morphometric analysis (eg, vessel counts, vascular...Several geometric configurations (discoid, spheroid, and so forth) were tested before selecting a cylindrical shape generated by a section of silicone

Workload Estimates for Combat Engineers in the Desert.

DTIC Science & Technology

1986-04-01

11111_!2 4 MICROCOP RES LU I N !ESICHR 111112 5 l *. ff APPENDIX B-8 BUILD A PROTECTIVE POSITION FOR A 155-MM TOWED HOWITZER 1. Terrain. Sandy Desert...the repeated cycles of dissolving calcium, silicon, and ferric compounds in the soil, followed by rapid evapora- tion. The result is a cemented top

Phase Diagram of the Al-Ca-Fe-Si System and Its Application for the Design of Aluminum Matrix Composites

NASA Astrophysics Data System (ADS)

Belov, Nikolay A.; Naumova, Evgeniya A.; Akopyan, Torgom K.; Doroshenko, Vitaliy V.

2018-05-01

The phase composition of aluminum alloys in the Al-Ca-Fe-Si system, including the distribution of phases in the solid state and solidification reactions, has been studied. It is shown that the addition of iron and silicon to Al-Ca alloys leads to the formation of ternary Al2CaSi2 and Al10CaFe2 compounds. The equilibrium between these compounds implies the occurrence of the quaternary L → Al + Al4Ca + Al2CaSi2 + Al10CaFe2 eutectic reaction. The alloys near this eutectic have the best structure, which is typical of aluminum matrix composites. It is shown that Al-Ca alloys can have high manufacturability during both shape casting and rolling. This is due to the combination of a narrow temperature range of solidification and a favorable morphology for the eutectic, which has a fine structure. The combination of the mechanical and physical properties of the Al-Ca eutectic-based alloys significantly exceed those of branded alloys based on aluminum-silicon eutectics.

Study of Surface Wettability Change of Unconsolidated Sand Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy and Thermogravimetric Analysis.

PubMed

Gómora-Herrera, Diana; Navarrete Bolaños, Juan; Lijanova, Irina V; Olivares-Xometl, Octavio; Likhanova, Natalya V

2018-04-01

The effects exerted by the adsorption of vapors of a non-polar compound (deuterated benzene) and a polar compound (water) on the surface of Ottawa sand and a sample of reservoir sand (Channel), which was previously impregnated with silicon oil or two kinds of surfactants, (2-hydroxyethyl) trimethylammonium oleate (HETAO) and (2-hydroxyethyl)trimethylammonium azelate (HETAA), were studied by diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and thermogravimetric analysis (TGA). The surface chemistry of the sandstone rocks was elucidated by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). Terminal surface groups such as hydroxyls can strongly adsorb molecules that interact with these surface groups (surfactants), resulting in a wettability change. The wettability change effect suffered by the surface after treating it with surfactants was possible to be detected by the DRIFTS technique, wherein it was observed that the surface became more hydrophobic after being treated with silicon oil and HETAO; the surface became more hydrophilic after treating it with HETAA.

Quantitative and qualitative studies of silica in different rice samples grown in north of Iran using UV-vis, XRD and IR spectroscopy techniques.

PubMed

Samadi-Maybodi, Abdolraouf; Atashbozorg, Ebrahim

2006-11-15

Silicon is an essential trace element and is found in vegetables, fruits, cereals, water, pasta and rice (Oryza sativa). In this work, the silica content of different types of rice grains were measured. Here, we used the heteropoly blue photometric method with a double beam UV-vis spectrophotometer to determine the amount of silicon in rice samples (n=7) that were collected in the north of Iran. The samples were digested with wet-ashing method by microwave-assisted heating and then treated with ammonium molybdate to produce a yellow color compound in acidic solution (ca. pH 1.2) and then reduced to give a heteropoly compound with a blue color. Analyses were performed using standard addition method and absorbance values were measured with double beam UV-vis spectrophotometer at lambda(max)=815nm. Results indicated that the silica content was 307-451mg/kg for the samples. X-ray diffraction patterns and infra-red spectra were obtained from rice samples without any sample treatment.

Silicon nitride boundary lubrication: Effect of oxygenates

NASA Astrophysics Data System (ADS)

Gates, Richard S.; Hsu, Stephen M.

1995-07-01

A ball-on-three-flat (BTF) wear tester was used to investigate the boundary lubricating characteristics of oxygenates on a commercial silicon nitride. A wide variety of oxygen-containing compounds containing hydroxyl functioal groups were more effective compared to a base case of neat paraffin oil. Decreases of up to 58% in friction coefficient, and 95% in wear were obtained. In most cases, films were obseved in and around the wear scar, suggesting chemical reactions had taken place in the contact. Additional wear tests, conducted using neat shorter-chain linear primary alcohols, i.e., 6-10 carbons, demonstrated boundary lubrication protection, with longer chain length providing better antiwear performance. A study of several C8 compounds with specific oxygen-containing functional groups (primary alcohol, secondary alcohols, acid, aldehyde, and ketone) demonstrated that the primary alcohol had the strongest boundary lubricating effect. Varying the amount of water in the alcohols had little effect on friction and wear, suggesting that the boundary lubrication effects observed were not merely due to dissolved water in these fluids, but some characteristic chemical interaction with the hydroxyl functional group of the alcohols and acids.

Thermal system design and modeling of meniscus controlled silicon growth process for solar applications

NASA Astrophysics Data System (ADS)

Wang, Chenlei

The direct conversion of solar radiation to electricity by photovoltaics has a number of significant advantages as an electricity generator. That is, solar photovoltaic conversion systems tap an inexhaustible resource which is free of charge and available anywhere in the world. Roofing tile photovoltaic generation, for example, saves excess thermal heat and preserves the local heat balance. This means that a considerable reduction of thermal pollution in densely populated city areas can be attained. A semiconductor can only convert photons with the energy of the band gap with good efficiency. It is known that silicon is not at the maximum efficiency but relatively close to it. There are several main parts for the photovoltaic materials, which include, single- and poly-crystalline silicon, ribbon silicon, crystalline thin-film silicon, amorphous silicon, copper indium diselenide and related compounds, cadmium telluride, et al. In this dissertation, we focus on melt growth of the single- and poly-crystalline silicon manufactured by Czochralski (Cz) crystal growth process, and ribbon silicon produced by the edge-defined film-fed growth (EFG) process. These two methods are the most commonly used techniques for growing photovoltaic semiconductors. For each crystal growth process, we introduce the growth mechanism, growth system design, general application, and progress in the numerical simulation. Simulation results are shown for both Czochralski and EFG systems including temperature distribution of the growth system, velocity field inside the silicon melt and electromagnetic field for the EFG growth system. Magnetic field is applied on Cz system to reduce the melt convection inside crucible and this has been simulated in our numerical model. Parametric studies are performed through numerical and analytical models to investigate the relationship between heater power levels and solidification interface movement and shape. An inverse problem control scheme is developed to control the solidification interface of Cz system by adjusting heater powers. For the EFG system, parametric studies are performed to discuss the effect of several growth parameters including window opening size, argon gas flow rate and growth thermal environment on the temperature distribution, silicon tube thickness and pulling rate. Two local models are developed and integrated with the global model to investigate the detailed transport phenomena in a small region around the solidification interface including silicon crystal, silicon melt, free surface, liquid-solid interface and graphite die design. Different convection forms are taken into consideration.

Intermetallic nickel silicide nanocatalyst—A non-noble metal–based general hydrogenation catalyst

PubMed Central

Pohl, Marga-Martina; Agapova, Anastasiya

2018-01-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO2 as the silicon atom source. The process involves thermal reduction of Si–O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon–carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal–based catalysts. PMID:29888329

B-H Bond Activation by an Amidinate-Stabilized Amidosilylene: Non-Innocent Amidinate Ligand.

PubMed

Khoo, Sabrina; Shan, Yu-Liang; Yang, Ming-Chung; Li, Yongxin; Su, Ming-Der; So, Cheuk-Wai

2018-05-21

The activation of B-H and B-Cl bonds in boranes by base-stabilized low-valent silicon compounds is described. The reaction of the amidinato amidosilylene-borane adduct [L{Ar(Me 3 Si)N}SiBH 3 ] [1; L = PhC(N tBu) 2 , and Ar = 2,6- iPr 2 C 6 H 3 ] with MeOTf in toluene at room temperature formed [L{Ar(Me 3 Si)N}SiBH 2 OTf] (2). [LSiN(SiMe 3 )Ar] in compound 2 then underwent a B-H bond activation with BH 2 OTf in refluxing toluene to afford the B-H bond activation product [LB(H)Si(H)(OTf){N(SiMe 3 )Ar}] (3). On the other hand, when compound 2 was reacted with 4-dimethylaminopyridine in refluxing toluene, another B-H bond activation product [(μ-κ1:κ1-L)B(H)(DMAP)Si(H){N(Ar)SiMe 3 }]OTf (4) was afforded. Mechanistic studies show that "(μ-κ1:κ1-L)B(H)(OTf)Si(H){N(Ar)SiMe 3 }" (2A) is the key intermediate in the reactions mentioned above. The formation of 2A is further evidenced by the activation of the B-Cl bond in PhBCl 2 by the amidinato silicon(I) dimer [LSi:] 2 to form the B-Cl bond activation product [(μ-κ1:κ1-L)B(Cl)(Ph)Si(Cl)] 2 (6). Compounds 2-4 and 6 were characterized by nuclear magnetic resonance spectroscopy and X-ray crystallography.

Large-scale metabolite analysis of standards and human serum by laser desorption ionization mass spectrometry from silicon nanopost arrays

DOE PAGES

Korte, Andrew R.; Stopka, Sylwia A.; Morris, Nicholas; ...

2016-07-11

The unique challenges presented by metabolomics have driven the development of new mass spectrometry (MS)-based techniques for small molecule analysis. We have previously demonstrated silicon nanopost arrays (NAPA) to be an effective substrate for laser desorption ionization (LDI) of small molecules for MS. However, the utility of NAPA-LDI-MS for a wide range of metabolite classes has not been investigated. Here we apply NAPA-LDI-MS to the large-scale acquisition of high-resolution mass spectra and tandem mass spectra from a collection of metabolite standards covering a range of compound classes including amino acids, nucleotides, carbohydrates, xenobiotics, lipids, and other classes. In untargeted analysismore » of metabolite standard mixtures, detection was achieved for 374 compounds and useful MS/MS spectra were obtained for 287 compounds, without individual optimization of ionization or fragmentation conditions. Metabolite detection was evaluated in the context of 31 metabolic pathways, and NAPA-LDI-MS was found to provide detection for 63% of investigated pathway metabolites. Individual, targeted analysis of the 20 common amino acids provided detection of 100% of the investigated compounds, demonstrating that improved coverage is possible through optimization and targeting of individual analytes or analyte classes. In direct analysis of aqueous and organic extracts from human serum samples, spectral features were assigned to a total of 108 small metabolites and lipids. Glucose and amino acids were quantitated within their physiological concentration ranges. Finally, the broad coverage demonstrated by this large-scale screening experiment opens the door for use of NAPA-LDI-MS in numerous metabolite analysis applications« less

Large-scale metabolite analysis of standards and human serum by laser desorption ionization mass spectrometry from silicon nanopost arrays

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

Korte, Andrew R.; Stopka, Sylwia A.; Morris, Nicholas

The unique challenges presented by metabolomics have driven the development of new mass spectrometry (MS)-based techniques for small molecule analysis. We have previously demonstrated silicon nanopost arrays (NAPA) to be an effective substrate for laser desorption ionization (LDI) of small molecules for MS. However, the utility of NAPA-LDI-MS for a wide range of metabolite classes has not been investigated. Here we apply NAPA-LDI-MS to the large-scale acquisition of high-resolution mass spectra and tandem mass spectra from a collection of metabolite standards covering a range of compound classes including amino acids, nucleotides, carbohydrates, xenobiotics, lipids, and other classes. In untargeted analysismore » of metabolite standard mixtures, detection was achieved for 374 compounds and useful MS/MS spectra were obtained for 287 compounds, without individual optimization of ionization or fragmentation conditions. Metabolite detection was evaluated in the context of 31 metabolic pathways, and NAPA-LDI-MS was found to provide detection for 63% of investigated pathway metabolites. Individual, targeted analysis of the 20 common amino acids provided detection of 100% of the investigated compounds, demonstrating that improved coverage is possible through optimization and targeting of individual analytes or analyte classes. In direct analysis of aqueous and organic extracts from human serum samples, spectral features were assigned to a total of 108 small metabolites and lipids. Glucose and amino acids were quantitated within their physiological concentration ranges. Finally, the broad coverage demonstrated by this large-scale screening experiment opens the door for use of NAPA-LDI-MS in numerous metabolite analysis applications« less

Intermetallic nickel silicide nanocatalyst-A non-noble metal-based general hydrogenation catalyst.

PubMed

Ryabchuk, Pavel; Agostini, Giovanni; Pohl, Marga-Martina; Lund, Henrik; Agapova, Anastasiya; Junge, Henrik; Junge, Kathrin; Beller, Matthias

2018-06-01

Hydrogenation reactions are essential processes in the chemical industry, giving access to a variety of valuable compounds including fine chemicals, agrochemicals, and pharmachemicals. On an industrial scale, hydrogenations are typically performed with precious metal catalysts or with base metal catalysts, such as Raney nickel, which requires special handling due to its pyrophoric nature. We report a stable and highly active intermetallic nickel silicide catalyst that can be used for hydrogenations of a wide range of unsaturated compounds. The catalyst is prepared via a straightforward procedure using SiO 2 as the silicon atom source. The process involves thermal reduction of Si-O bonds in the presence of Ni nanoparticles at temperatures below 1000°C. The presence of silicon as a secondary component in the nickel metal lattice plays the key role in its properties and is of crucial importance for improved catalytic activity. This novel catalyst allows for efficient reduction of nitroarenes, carbonyls, nitriles, N-containing heterocycles, and unsaturated carbon-carbon bonds. Moreover, the reported catalyst can be used for oxidation reactions in the presence of molecular oxygen and is capable of promoting acceptorless dehydrogenation of unsaturated N-containing heterocycles, opening avenues for H 2 storage in organic compounds. The generality of the nickel silicide catalyst is demonstrated in the hydrogenation of over a hundred of structurally diverse unsaturated compounds. The wide application scope and high catalytic activity of this novel catalyst make it a nice alternative to known general hydrogenation catalysts, such as Raney nickel and noble metal-based catalysts.

Study on real-time images compounded using spatial light modulator

NASA Astrophysics Data System (ADS)

Xu, Jin; Chen, Zhebo; Ni, Xuxiang; Lu, Zukang

2007-01-01

Image compounded technology is often used on film and its facture. In common, image compounded use image processing arithmetic, get useful object, details, background or some other things from the images firstly, then compounding all these information into one image. When using this method, the film system needs a powerful processor, for the process function is very complex, we get the compounded image for a few time delay. In this paper, we introduce a new method of image real-time compounded, use this method, we can do image composite at the same time with movie shot. The whole system is made up of two camera-lens, spatial light modulator array and image sensor. In system, the spatial light modulator could be liquid crystal display (LCD), liquid crystal on silicon (LCoS), thin film transistor liquid crystal display (TFTLCD), Deformable Micro-mirror Device (DMD), and so on. Firstly, one camera-lens images the object on the spatial light modulator's panel, we call this camera-lens as first image lens. Secondly, we output an image to the panel of spatial light modulator. Then, the image of the object and image that output by spatial light modulator will be spatial compounded on the panel of spatial light modulator. Thirdly, the other camera-lens images the compounded image to the image sensor, and we call this camera-lens as second image lens. After these three steps, we will gain the compound images by image sensor. For the spatial light modulator could output the image continuously, then the image will be compounding continuously too, and the compounding procedure is completed in real-time. When using this method to compounding image, if we will put real object into invented background, we can output the invented background scene on the spatial light modulator, and the real object will be imaged by first image lens. Then, we get the compounded images by image sensor in real time. The same way, if we will put real background to an invented object, we can output the invented object on the spatial light modulator and the real background will be imaged by first image lens. Then, we can also get the compounded images by image sensor real time. Commonly, most spatial light modulator only can do modulate light intensity, so we can only do compounding BW images if use only one panel which without color filter. If we will get colorful compounded image, we need use the system like three spatial light modulator panel projection. In the paper, the system's optical system framework we will give out. In all experiment, the spatial light modulator used liquid crystal on silicon (LCoS). At the end of the paper, some original pictures and compounded pictures will be given on it. Although the system has a few shortcomings, we can conclude that, using this system to compounding images has no delay to do mathematic compounding process, it is a really real time images compounding system.

Feasibility of atmospheric pressure desorption/ionization on silicon mass spectrometry in analysis of drugs.

PubMed

Huikko, K; Ostman, P; Sauber, C; Mandel, F; Grigoras, K; Franssila, S; Kotiaho, T; Kostiainen, R

2003-01-01

The feasibility of atmospheric pressure desorption/ionization on silicon mass spectrometry (AP-DIOS-MS) for drug analysis was investigated. It was observed that only compounds with relative high proton affinity are efficiently ionized under AP-DIOS conditions. The limits of detection (LODs) achieved in MS mode with midazolam, propranolol, and angiotensin II were 80 fmol, 20 pmol, and 1 pmol, respectively. In MS/MS mode the LODs for midazolam and propranolol were 10 fmol and 5 pmol, respectively. The good linearity (r(2) > 0.991), linear dynamic range of 3 orders of magnitude, and reasonable repeatability showed that the method is suitable for quantitative analysis. Copyright 2003 John Wiley & Sons, Ltd.

Modified silicon carbide whiskers

DOEpatents

Tiegs, Terry N.; Lindemer, Terrence B.

1991-01-01

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Modified silicon carbide whiskers

DOEpatents

Tiegs, T.N.; Lindemer, T.B.

1991-05-21

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

DOEpatents

Tiegs, Terry N.; Lindemer, Terrence B.

1991-01-01

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Ceramic composites reinforced with modified silicon carbide whiskers and method for modifying the whiskers

DOEpatents

Tiegs, T.N.; Lindemer, T.B.

1991-02-19

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Ceramic composites reinforced with modified silicon carbide whiskers

DOEpatents

Tiegs, Terry N.; Lindemer, Terrence B.

1990-01-01

Silicon carbide whisker-reinforced ceramic composites are fabricated in a highly reproducible manner by beneficating the surfaces of the silicon carbide whiskers prior to their usage in the ceramic composites. The silicon carbide whiskers which contain considerable concentrations of surface oxides and other impurities which interact with the ceramic composite material to form a chemical bond are significantly reduced so that only a relatively weak chemical bond is formed between the whisker and the ceramic material. Thus, when the whiskers interact with a crack propagating into the composite the crack is diverted or deflected along the whisker-matrix interface due to the weak chemical bonding so as to deter the crack propagation through the composite. The depletion of the oxygen-containing compounds and other impurities on the whisker surfaces and near surface region is effected by heat treating the whiskers in a suitable oxygen sparaging atmosphere at elevated temperatures. Additionally, a sedimentation technique may be utilized to remove whiskers which suffer structural and physical anomalies which render them undesirable for use in the composite. Also, a layer of carbon may be provided on the surface of the whiskers to further inhibit chemical bonding of the whiskers to the ceramic composite material.

Silicone Oil Microdroplets and Protein Aggregates in Repackaged Bevacizumab and Ranibizumab: Effects of Long-term Storage and Product Mishandling

PubMed Central

Liu, Lu; Ammar, David A.; Ross, Lindsey A.; Mandava, Naresh; Kahook, Malik Y.

2011-01-01

Purpose. To quantify levels of subvisible particles and protein aggregates in repackaged bevacizumab obtained from compounding pharmacies, as well as in samples of bevacizumab and ranibizumab tested in controlled laboratory experiments. Methods. Repackaged bevacizumab was purchased from four external compounding pharmacies. For controlled laboratory studies, bevacizumab and placebo were drawn into plastic syringes and incubated at −20°C, 4°C, and room temperature (with and without exposure to light) for 12 weeks. In addition, mechanical shock occurring during shipping was mimicked with syringes containing bevacizumab. Particle counts and size distributions were quantified by particle characterization technology. Levels of monomer and soluble aggregates of bevacizumab were determined with size-exclusion high-performance liquid chromatography (SE-HPLC). Results. Repackaged bevacizumab from the compounding pharmacies had a wide range of particle counts (89,006 ± 56,406 to 602,062 ± 18,349/mL). Bevacizumab sampled directly from the original glass vial had particle counts of 63,839 ± 349/mL. There was up to a 10% monomer loss in the repackaged bevacizumab. Laboratory samples of repackaged bevacizumab and placebo had initial particle counts, respectively, of 283,675 ± 60,494/mL and 492,314 ± 389,361/mL. Freeze-thawing of both bevacizumab and placebo samples led to >1.2 million particles/mL. In all repackaged samples, most of the particles were due to silicone oil. SE-HPLC showed no significant differences for repackaged samples incubated in the laboratory under various conditions, compared with bevacizumab directly from vial. However, repeated freeze-thawing caused a more than 10% monomer loss. Conclusions. Bevacizumab repackaged in plastic syringes could contain protein aggregates and is contaminated by silicone oil microdroplets. Freeze-thawing or other mishandling can further increase levels of particle contaminants. PMID:21051703

Acetylcholinesterase immobilization and characterization, and comparison of the activity of the porous silicon-immobilized enzyme with its free counterpart.

PubMed

Saleem, Muhammad; Rafiq, Muhammad; Seo, Sung-Yum; Lee, Ki Hwan

2016-02-02

A successful prescription is presented for acetylcholinesterase physically adsorbed on to a mesoporous silicon surface, with a promising hydrolytic response towards acetylthiocholine iodide. The catalytic behaviour of the immobilized enzyme was assessed by spectrophotometric bioassay using neostigmine methyl sulfate as a standard acetycholinesterase inhibitor. The surface modification was studied through field emission SEM, Fourier transform IR spectroscopy, energy-dispersive X-ray spectroscopy, cathode luminescence and X-ray photoelectron spectroscopy analysis, photoluminescence measurement and spectrophotometric bioassay. The porous silicon-immobilized enzyme not only yielded greater enzyme stability, but also significantly improved the native photoluminescence at room temperature of the bare porous silicon architecture. The results indicated the promising catalytic behaviour of immobilized enzyme compared with that of its free counterpart, with a greater stability, and that it aided reusability and easy separation from the reaction mixture. The porous silicon-immobilized enzyme was found to retain 50% of its activity, promising thermal stability up to 90°C, reusability for up to three cycles, pH stability over a broad pH of 4-9 and a shelf-life of 44 days, with an optimal hydrolytic response towards acetylthiocholine iodide at variable drug concentrations. On the basis of these findings, it was believed that the porous silicon-immobilized enzyme could be exploited as a reusable biocatalyst and for screening of acetylcholinesterase inhibitors from crude plant extracts and synthesized organic compounds. Moreover, the immobilized enzyme could offer a great deal as a viable biocatalyst in bioprocessing for the chemical and pharmaceutical industries, and bioremediation to enhance productivity and robustness. © 2016 Authors.

Acetylcholinesterase immobilization and characterization, and comparison of the activity of the porous silicon-immobilized enzyme with its free counterpart

PubMed Central

Saleem, Muhammad; Rafiq, Muhammad; Seo, Sung-Yum; Lee, Ki Hwan

2016-01-01

A successful prescription is presented for acetylcholinesterase physically adsorbed on to a mesoporous silicon surface, with a promising hydrolytic response towards acetylthiocholine iodide. The catalytic behaviour of the immobilized enzyme was assessed by spectrophotometric bioassay using neostigmine methyl sulfate as a standard acetycholinesterase inhibitor. The surface modification was studied through field emission SEM, Fourier transform IR spectroscopy, energy-dispersive X-ray spectroscopy, cathode luminescence and X-ray photoelectron spectroscopy analysis, photoluminescence measurement and spectrophotometric bioassay. The porous silicon-immobilized enzyme not only yielded greater enzyme stability, but also significantly improved the native photoluminescence at room temperature of the bare porous silicon architecture. The results indicated the promising catalytic behaviour of immobilized enzyme compared with that of its free counterpart, with a greater stability, and that it aided reusability and easy separation from the reaction mixture. The porous silicon-immobilized enzyme was found to retain 50% of its activity, promising thermal stability up to 90°C, reusability for up to three cycles, pH stability over a broad pH of 4–9 and a shelf-life of 44 days, with an optimal hydrolytic response towards acetylthiocholine iodide at variable drug concentrations. On the basis of these findings, it was believed that the porous silicon-immobilized enzyme could be exploited as a reusable biocatalyst and for screening of acetylcholinesterase inhibitors from crude plant extracts and synthesized organic compounds. Moreover, the immobilized enzyme could offer a great deal as a viable biocatalyst in bioprocessing for the chemical and pharmaceutical industries, and bioremediation to enhance productivity and robustness. PMID:26839417

Method of forming a relatively stable slip of silicon metal particles and yttrium containing particles

DOEpatents

Dickie, Ray A.; Mangels, John A.

1984-01-01

The method concerns forming a relatively stable slip of silicon metal particles and yttrium containing particles. In one embodiment, a casting slip of silicon metal particles is formed in water. Particles of a yttrium containing sintering aid are added to the casting slip. The yttrium containing sintering aid is a compound which has at least some solubility in water to form Y.sup.+3 ions which have a high potential for totally flocculating the silicon metal particles into a semiporous solid. A small amount of a fluoride salt is added to the casting slip which contains the yttrium containing sintering aid. The fluoride salt is one which will produce fluoride anions when dissolved in water. The small amount of the fluoride anions produced are effective to suppress the flocculation of the silicon metal particles by the Y.sup.+3 ions so that all particles remain in suspension in the casting slip and the casting slip has both an increased shelf life and can be used to cast articles having a relatively thick cross-section. The pH of the casting slip is maintained in a range from 7.5 to 9. Preferably, the fluoride salt used is one which is based on a monovalent cation such as sodium or ammonia. The steps of adding the yttrium containing sintering aid and the fluoride salt may be interchanged if desired, and the salt may be added to a solution containing the sintering aid prior to addition of the silicon metal particles.

Interference in adhesion of bacteria and yeasts isolated from explanted voice prostheses to silicone rubber by rhamnolipid biosurfactants.

PubMed

Rodrigues, L R; Banat, I M; van der Mei, H C; Teixeira, J A; Oliveira, R

2006-03-01

The effects and extent of adhesion of four different bacterial and two yeast strains isolated from explanted voice prostheses to silicone rubber with and without an adsorbed rhamnolipid biosurfactant layer obtained from Pseudomonasaeruginosa DS10-129 was studied. The ability of rhamnolipid biosurfactant to inhibit adhesion of micro-organisms to silicone rubber was investigated in a parallel-plate flow chamber. The anti-adhesive activity of the biosurfactant at different concentrations was significant against all the strains and depended on the micro-organism tested. The results showed an effective reduction in the initial deposition rates, and the number of bacterial cells adhering after 4 h, for all micro-organisms tested at the 4 g l(-1) undiluted rhamnolipid solution. Maximum initial reduction of adhesion rate (an average of 66%) occurred for Streptococcus salivarius GB 24/9 and Candida tropicalis GB 9/9. The number of cells adhering after 4 h on silicone rubber conditioned with biosurfactant was reduced to 48% for Staphylococcus epidermidis GB 9/6, Strep. salivarius GB 24/9, Staphylococcus aureus GB 2/1 and C. tropicalis GB 9/9 in comparison to controls. Perfusing the flow chamber with biosurfactant containing solution followed by the passage of a liquid-air interface, to investigate detachment of micro-organisms adhering to silicone rubber, produced high detachment (96%) of adhered cells for all micro-organisms studied, except for Staph. aureus GB 2/1 (67%). It is concluded that biosurfactant represent suitable compounds that should be considered in developing future strategies to prevent the microbial colonization of silicone rubber voice prostheses.

Effect of light elements on the sound velocities in solid iron: Implications for the composition of Earth's core

NASA Astrophysics Data System (ADS)

Badro, James; Fiquet, Guillaume; Guyot, François; Gregoryanz, Eugene; Occelli, Florent; Antonangeli, Daniele; d'Astuto, Matteo

2007-02-01

We measured compressional sound velocities in light element alloys of iron (FeO, FeSi, FeS, and FeS2) at high-pressure by inelastic X-ray scattering. This dataset provides new mineralogical constraints on the composition of Earth's core, and completes the previous sets formed by the pressure-density systematics for these compounds. Based on the combination of these datasets and their comparison with radial seismic models, we propose an average composition model of the Earth's core. We show that the incorporation of small amounts of silicon or oxygen is compatible with geophysical observations and geochemical abundances. The effect of nickel on the calculated light element contents is shown to be negligible. The preferred core model derived from our measurements is an inner core which contains 2.3 wt.% silicon and traces of oxygen, and an outer core containing 2.8 wt.% silicon and around 5.3 wt.% oxygen.

Chemistry challenges in lead optimization: silicon isosteres in drug discovery.

PubMed

Showell, Graham A; Mills, John S

2003-06-15

During the lead optimization phase of drug discovery projects, the factors contributing to subsequent failure might include poor portfolio decision-making and a sub-optimal intellectual property (IP) position. The pharmaceutical industry has an ongoing need for new, safe medicines with a genuine biomedical benefit, a clean IP position and commercial viability. Inherent drug-like properties and chemical tractability are also essential for the smooth development of such agents. The introduction of bioisosteres, to improve the properties of a molecule and obtain new classes of compounds without prior art in the patent literature, is a key strategy used by medicinal chemists during the lead optimization process. Sila-substitution (C/Si exchange) of existing drugs is an approach to search for new drug-like candidates that have beneficial biological properties and a clear IP position. Some of the fundamental differences between carbon and silicon can lead to marked alterations in the physicochemical and biological properties of the silicon-containing analogues and the resulting benefits can be exploited in the drug design process.

Solid-dielectric compound parabolic concentrators: on their use with photovoltaic devices.

PubMed

Goodman, N B; Ignatius, R; Wharton, L; Winston, R

1976-10-01

Prototype solid dielectric compound parabolic concentrators have been made and tested. By means of the geometry and refractive properties of a transparent solid they provide a technique for increasing the power output of silicon solar cells exposed to the sun by an amount nearly equal to the increase in effective collecting area. The response is uniform over a large angle which eliminates the necessity of diurnal tracking of the sun. The technique can be applied to the construction of thin panels and has the potential for significantly reducing, their cost per unit area.

MOD silver metallization for photovoltaics

NASA Technical Reports Server (NTRS)

Vest, G. M.; Vest, R. W.

1984-01-01

The development of flat plate solar arrays is reported. Photovoltaic cells require back side metallization and a collector grid system on the front surface. Metallo-organic decomposition (MOD) silver films can eliminate most of the present problems with silver conductors. The objectives are to: (1) identify and characterize suitable MO compounds; (2) develop generic synthesis procedures for the MO compounds; (3) develop generic fabrication procedures to screen printable MOD silver inks; (4) optimize processing conditions to produce grid patterns and photovoltaic cells; and (5) develop a model which describes the adhesion between the fired silver film and the silicon surface.

Lewis base catalyzed 1,3-dithiane addition to carbonyl and imino compounds using 2-trimethylsilyl-1,3-dithiane.

PubMed

Michida, Makoto; Mukaiyama, Teruaki

2008-09-01

Lewis base-catalyzed 1,3-dithiane addition to electrophiles such as carbonyl compounds and N-substituted aldimines with 2-trimethylsilyl-1,3-dithiane (TMS-dithiane) is described. By the activation of the carbon-silicon bond in the presence of a Lewis base catalyst such as tetrabutylammonium phenoxide (PhONnBu(4)), a 1,3-dithiane addition reaction proceeded smoothly to afford the corresponding adducts in good to high yields under mild conditions. This synthesis is also applied to the reactions of ketones having alpha-protons, and of N-substituted aldimines.

Exploratory study of elevated-temperature tensile properties of alloys based on the intermetallic compound TiNi

NASA Technical Reports Server (NTRS)

Garfinkle, M.

1974-01-01

The tensile properties and oxygen contamination behavior of TiNi alloyed with aluminum, chromium, and silicon were investigated in the temperature range between 800 and 1000 K (980 and 1340 F). The alloys were significantly stronger than unalloyed TiNi and less susceptible to embrittlement than the Ti-6242 alloy.

Alcohol-free alkoxide process for containing nuclear waste

DOEpatents

Pope, James M.; Lahoda, Edward J.

1984-01-01

Disclosed is a method of containing nuclear waste. A composition is first prepared of about 25 to about 80%, calculated as SiO.sub.2, of a partially hydrolyzed silicon compound, up to about 30%, calculated as metal oxide, of a partially hydrolyzed aluminum or calcium compound, about 5 to about 20%, calculated as metal oxide, of a partially hydrolyzed boron or calcium compound, about 3 to about 25%, calculated as metal oxide, of a partially hydrolyzed sodium, potassium or lithium compound, an alcohol in a weight ratio to hydrolyzed alkoxide of about 1.5 to about 3% and sufficient water to remove at least 99% of the alcohol as an azeotrope. The azeotrope is boiled off and up to about 40%, based on solids in the product, of the nuclear waste, is mixed into the composition. The mixture is evaporated to about 25 to about 45% solids and is melted and cooled.

Holographic detection of hydrocarbon gases and other volatile organic compounds.

PubMed

Martínez-Hurtado, J L; Davidson, C A B; Blyth, J; Lowe, C R

2010-10-05

There is a need to develop sensors for real-time monitoring of volatile organic compounds (VOCs) and hydrocarbon gases in both external and indoor environments, since these compounds are of growing concern in human health and welfare. Current measurement technology for VOCs requires sophisticated equipment and lacks the prospect for rapid real-time monitoring. Holographic sensors can give a direct reading of the analyte concentration as a color change. We report a technique for recording holographic sensors by laser ablation of silver particles formed in situ by diffusion. This technique allows a readily available hydrophobic silicone elastomer to be transformed into an effective sensor for hydrocarbon gases and other volatile compounds. The intermolecular interactions present between the polymer and molecules are used to predict the sensor performance. The hydrophobicity of this material allows the sensor to operate without interference from water and other atmospheric gases and thus makes the sensor suitable for biomedical, industrial, or environmental analysis.

Multijunction photovoltaic device and method of manufacture

DOEpatents

Arya, Rejeewa R.; Catalano, Anthony W.; Bennett, Murray

1995-04-04

A multijunction photovoltaic device includes first, second, and third amorphous silicon p-i-n photovoltaic cells in a stacked arrangement. The intrinsic layers of the second and third cells are formed of a-SiGe alloys with differing ratios of Ge such that the bandgap of the intrinsic layers respectively decrease from the first uppermost cell to the third lowermost cell. An interface layer, composed of a doped silicon compound, is disposed between the two cells and has a lower bandgap than the respective n- and p-type adjacent layers of the first and second cells. The interface layer forms an ohmic contact with the one of the adjacent cell layers of the same conductivity type, and a tunnel junction with the other of the adjacent cell layers.

Variation of the shape and morphological properties of silica and metal oxide powders by electro homogeneous precipitation

DOEpatents

Harris, M.T.; Basaran, O.A.; Sisson, W.G.; Brunson, R.R.

1997-02-18

The present invention provides a method for preparing irreversible linear aggregates (fibrils) of metal oxide powders by utilizing static or pulsed DC electrical fields across a relatively non-conducting liquid solvent in which organometal compounds or silicon alkoxides have been dissolved. The electric field is applied to the relatively non-conducting solution throughout the particle formation and growth process promoting the formation of either linear aggregates (fibrils) or spherical shaped particles as desired. Thus the present invention provides a physical method for altering the size, shape and porosity of precursor hydrous metal oxide or hydrous silicon oxide powders for the development of advanced ceramics with improved strength and insulating capacity. 3 figs.

Improved toughness of refractory compounds. [with elimination of the grain boundary phase

NASA Technical Reports Server (NTRS)

Wright, T. R.; Niesz, D. E.

1974-01-01

The concept of grain-boundary-engineering through elimination of the grain-boundary silicate phase in silicon nitride was developed. The process involved removal of the silica from the nitride powder via a thermal treatment coupled with the use of nitride additives to compensate the remaining oxygen. Magnesium and aluminum nitrides are found to be the most effective additive for use as oxygen compensators. Strength decreases at elevated temperatures are not observed in the alumina containing material. The creep rate of a dual additive sialon composition was two orders of magnitude lower at 1400 C than commercial silicon nitride. A cursory analysis of the creep mechanism indicate that grain-boundary sliding is avoided through elimination of the grain-boundary silicate phase.

Investigation of the mechanical properties of FeNiCrMnSi high entropy alloy wear resistant

NASA Astrophysics Data System (ADS)

Buluc, G.; Florea, I.; Chelariu, R.; Popescu, G.; Carcea, I.

2016-06-01

In this paper we investigated microstructure, hardness and wear resistance for FeNiCrMnAl, high entropy alloy. The FeNiCrMnSi, high entropy alloy was elaborated in a medium induction furnace, by choosing the silicon, as an alliance element within the equi- atomic high entropy alloy, we managed to obtain a dendritic structure, the formation of intermetallic compounds or separated silicon. The medium hardness value of the investigated alloy was 948.33 HV and the medium value of the friction coefficient was 0.6655 in the first 20 seconds and 0.5425 for 1667 seconds. The volume loss of the high entropy alloy FeNiCrMnSi was 0.0557 mm3.

Comparison of the sampling rates and partitioning behaviour of polar and non-polar contaminants in the polar organic chemical integrative sampler and a monophasic mixed polymer sampler for application as an equilibrium passive sampler.

PubMed

Jeong, Yoonah; Schäffer, Andreas; Smith, Kilian

2018-06-15

In this work, Oasis HLB® beads were embedded in a silicone matrix to make a single phase passive sampler with a higher affinity for polar and ionisable compounds than silicone alone. The applicability of this mixed polymer sampler (MPS) was investigated for 34 aquatic contaminants (log K OW -0.03 to 6.26) in batch experiments. The influence of flow was investigated by comparing uptake under static and stirred conditions. The sampler characteristics of the MPS was assessed in terms of sampling rates (R S ) and sampler-water partition coefficients (K SW ), and these were compared to those of the polar organic chemical integrative sampler (POCIS) as a reference kinetic passive sampler. The MPS was characterized as an equilibrium sampler for both polar and non-polar compounds, with faster uptake rates and a shorter time to reach equilibrium than the POCIS. Water flow rate impacted sampling rates by up to a factor of 12 when comparing static and stirred conditions. In addition, the relative accumulation of compounds in the polyethersulfone (PES) membranes versus the inner Oasis HLB sorbent was compared for the POCIS, and ranged from <1% to 83% depending on the analyte properties. This is indicative of a potentially significant lag-phase for less polar compounds within POCIS. The findings of this study can be used to quantitatively describe the partitioning and kinetic behaviour of MPS and POCIS for a range of aquatic organic contaminants for application in field sampling. Copyright © 2018 Elsevier B.V. All rights reserved.

Analytical methodology for sampling and analysing eight siloxanes and trimethylsilanol in biogas from different wastewater treatment plants in Europe.

PubMed

Raich-Montiu, J; Ribas-Font, C; de Arespacochaga, N; Roig-Torres, E; Broto-Puig, F; Crest, M; Bouchy, L; Cortina, J L

2014-02-17

Siloxanes and trimethylsilanol belong to a family of organic silicone compounds that are currently used extensively in industry. Those that are prone to volatilisation become minor compounds in biogas adversely affecting energetic applications. However, non-standard analytical methodologies are available to analyse biogas-based gaseous matrixes. To this end, different sampling techniques (adsorbent tubes, impingers and tedlar bags) were compared using two different configurations: sampling directly from the biogas source or from a 200 L tedlar bag filled with biogas and homogenised. No significant differences were apparent between the two sampling configurations. The adsorbent tubes performed better than the tedlar bags and impingers, particularly for quantifying low concentrations. A method for the speciation of silicon compounds in biogas was developed using gas chromatography coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimised conditions could separate and quantify eight siloxane compounds (L2, L3, L4, L5, D3, D4, D5 and D6) and trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain, France and England was sampled and analysed using the developed methodology. The siloxane concentrations in the biogas samples were influenced by the anaerobic digestion temperature, as well as the nature and composition of the sewage inlet. Siloxanes D4 and D5 were the most abundant, ranging in concentration from 1.5 to 10.1 and 10.8 to 124.0 mg Nm(-3), respectively, and exceeding the tolerance limit of most energy conversion systems. Copyright © 2013 Elsevier B.V. All rights reserved.

Comparative analysis of germanium-silicon quantum dots formation on Si(100), Si(111) and Sn/Si(100) surfaces

NASA Astrophysics Data System (ADS)

Lozovoy, Kirill; Kokhanenko, Andrey; Voitsekhovskii, Alexander

2018-02-01

In this paper theoretical modeling of formation and growth of germanium-silicon quantum dots in the method of molecular beam epitaxy (MBE) on different surfaces is carried out. Silicon substrates with crystallographic orientations (100) and (111) are considered. Special attention is paid to the question of growth of quantum dots on the silicon surface covered by tin, since germanium-silicon-tin system is extremely important for contemporary nano- and optoelectronics: for creation of photodetectors, solar cells, light-emitting diodes, and fast-speed transistors. A theoretical approach for modeling growth processes of such semiconductor compounds during the MBE is presented. Both layer-by-layer and island nucleation stages in the Stranski-Krastanow growth mode are described. A change in free energy during transition of atoms from the wetting layer to an island, activation barrier of the nucleation, critical thickness of 2D to 3D transition, as well as surface density and size distribution function of quantum dots in these systems are calculated with the help of the established model. All the theoretical speculations are carried out keeping in mind possible device applications of these materials. In particular, it is theoretically shown that using of the Si(100) surface covered by tin as a substrate for Ge deposition may be very promising for increasing size homogeneity of quantum dot array for possible applications in low-noise selective quantum dot infrared photodetectors.

Comparative analysis of germanium-silicon quantum dots formation on Si(100), Si(111) and Sn/Si(100) surfaces.

PubMed

Lozovoy, Kirill; Kokhanenko, Andrey; Voitsekhovskii, Alexander

2018-02-02

In this paper theoretical modeling of formation and growth of germanium-silicon quantum dots in the method of molecular beam epitaxy (MBE) on different surfaces is carried out. Silicon substrates with crystallographic orientations (100) and (111) are considered. Special attention is paid to the question of growth of quantum dots on the silicon surface covered by tin, since germanium-silicon-tin system is extremely important for contemporary nano- and optoelectronics: for creation of photodetectors, solar cells, light-emitting diodes, and fast-speed transistors. A theoretical approach for modeling growth processes of such semiconductor compounds during the MBE is presented. Both layer-by-layer and island nucleation stages in the Stranski-Krastanow growth mode are described. A change in free energy during transition of atoms from the wetting layer to an island, activation barrier of the nucleation, critical thickness of 2D to 3D transition, as well as surface density and size distribution function of quantum dots in these systems are calculated with the help of the established model. All the theoretical speculations are carried out keeping in mind possible device applications of these materials. In particular, it is theoretically shown that using of the Si(100) surface covered by tin as a substrate for Ge deposition may be very promising for increasing size homogeneity of quantum dot array for possible applications in low-noise selective quantum dot infrared photodetectors.

Field repair of AH-16 helicopter window cutting assemblies

NASA Technical Reports Server (NTRS)

Bement, L. J.

1984-01-01

The U.S. Army uses explosively actuated window cutting assemblies to provide emergency crew ground egress. Gaps between the system's explosive cords and acrylic windows caused a concern about functional reliability for a fleet of several hundred aircraft. A field repair method, using room temperature vulcanizing silicone compound (RTV), was developed and demonstrated to fill gaps as large as 0.250 inch.

Organic Thin Films for Photonics Applications. Volume 14

DTIC Science & Technology

1997-01-01

progress of the polymer optical fiber (POF) and related photonics polymer for high-speed telecommunication is reviewed. The high-bandwidth perfluorinated ...silicon. In the waveguide spectrometry studies described above, ab- sorption was measured on slab waveguides where fabrication imperfections are... compound in scries I[//| and II|//| , we have determined in solution: - the ground-state dipole /{ using capacitive measurements - the static

Improved Ceramic Anodes for Corrosion Protection.

DTIC Science & Technology

1984-11-01

34 . 4 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE(Whi Data Entered) BLOCK 20 (Continued) ferrite over niobium over Ni- Cr -AI-Y...plasma-sprayed lithium ferrite on a valve metal substrate. Donor doped and reduced solid sintered titanate compounds yielded electrically conductive...Traditionally. impressed current systems have used tion (CEGS) 2310. antides that are either inexpensive and very large (high silicon, chromium

Diffusion welded nonconsumable electrode assembly and use thereof for electrolytic production of metals and silicon

DOEpatents

Byrne, Stephen C.; Vasudevan, Asuri K.

1984-01-01

A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor diffusion welded to a portion of a ceramic electrode body having a level of free metal or metal alloy sufficient to effect a metal bond.

Studies of Silicon Refractory Metal Interfaces: Photoemission Study of Interface Formation and Compound Nucleation.

DTIC Science & Technology

1983-09-08

1982). 4. A. Hiraki , M.-A. Nicolet, and J.W. Mayer, Appl. Phys. Lett. 18, 178 (1971); A. Hiraki , K. Shuto, S. Kim, W. Kammura, and M. twami, ibid 31...Vac. Sci. Technol. 17, 930 (1980) and references therein. 13 T. Narusera, K. Kinoehica, W. 1. Gibson, and A. Hiraki , J. Vac. Sci. Technol. L$, 272

Particle size distribution of aerosols sprayed from household hand-pump sprays containing fluorine-based and silicone-based compounds.

PubMed

Kawakami, Tsuyoshi; Isama, Kazuo; Ikarashi, Yoshiaki

2015-01-01

Japan has published safety guideline on waterproof aerosol sprays. Furthermore, the Aerosol Industry Association of Japan has adopted voluntary regulations on waterproof aerosol sprays. Aerosol particles of diameter less than 10 µm are considered as "fine particles". In order to avoid acute lung injury, this size fraction should account for less than 0.6% of the sprayed aerosol particles. In contrast, the particle size distribution of aerosols released by hand-pump sprays containing fluorine-based or silicone-based compounds have not been investigated in Japan. Thus, the present study investigated the aerosol particle size distribution of 16 household hand-pump sprays. In 4 samples, the ratio of fine particles in aerosols exceeded 0.6%. This study confirmed that several hand-pump sprays available in the Japanese market can spray fine particles. Since the hand-pump sprays use water as a solvent and their ingredients may be more hydrophilic than those of aerosol sprays, the concepts related to the safety of aerosol-sprays do not apply to the hand pump sprays. Therefore, it may be required for the hand-pump spray to develop a suitable method for evaluating the toxicity and to establish the safety guideline.

Discovery and Identification of Dimethylsilanediol as a Contaminant in ISS Potable Water

NASA Technical Reports Server (NTRS)

Rutz, Jeffrey A.; Schultz, John R.; Kuo, C. Mike; Cole, Hraold E.; Manuel, Sam; Curtis, Matthew; Jones, Patrick R.; Sparkman, O. David; McCoy, J. Torin

2010-01-01

In September of 2010, analysis of ISS potable water samples was undertaken to determine the contaminant responsible for a rise in total organic carbon (TOC). As analysis of the routine target list of organic compounds did not reveal the contaminant, efforts to look for unknown compounds was initiated, resulting in an unknown peak being discovered in the gas chromatography/mass spectrometry (GC/MS) analysis for glycols. A mass spectrum of the contaminant was then generated by concentrating one of the samples by evaporation and analyzing by GC/MS in full-scan mode. Although a computer match of the compound s identity could not be obtained with the instrument s database, a search with a more up to date mass spectral library yielded a good match with dimethylsilanediol (DMSD). Inductively Coupled Plasma/Mass Spectrometry (ICP/MS) analyses showed abnormally high silicon levels in the samples, confirming that the unknown contained silicon. DMSD was then synthesized to confirm the identification and provide a standard to develop a calibration curve. Further confirmation was provided by external Direct Analysis in Real Time (DART) GC/MS analysis. A preliminary GC/MS method was then developed and archived samples from various locations on ISS were analyzed to determine the extent of the contamination and provide data for troubleshooting. This paper describes these events in more detail as well as problems encountered in routine GC/MS analyses and the subsequent development of high performance liquid chromatography and LC/MS/MS methods for quantitation of DMSD.

Surface morphology of molybdenum silicide films upon low-energy ion beam sputtering

NASA Astrophysics Data System (ADS)

Gago, R.; Jaafar, M.; Palomares, F. J.

2018-07-01

The surface morphology of molybdenum silicide (Mo x Si1‑x ) films has been studied after low-energy Ar+ ion beam sputtering (IBS) to explore eventual pattern formation on compound targets and, simultaneously, gather information about the mechanisms behind silicide-assisted nanopatterning of silicon surfaces by IBS. For this purpose, Mo x Si1‑x films with compositions below, equal and above the MoSi2 stoichiometry (x  =  0.33) have been produced by magnetron sputtering, as assessed by Rutherford backscattering spectrometry (RBS). The surface morphology of silicon and silicide films before and after IBS has been imaged by atomic force microscopy (AFM), comprising conditions where typical nanodot or ripple patterns emerge on the former. In the case of irradiated Mo x Si1‑x surfaces, AFM shows a marked surface smoothing at normal incidence with and without additional Mo incorporation (the former results in nanodot patterns on Si). The morphological analysis also provides no evidence of ion-induced phase separation in irradiated Mo x Si1‑x . Contrary to silicon, Mo x Si1‑x surfaces also do not display ripple formation for (impurity free) oblique irradiations, except at grazing incidence conditions where parallel ripples emerge in a more evident fashion than in the Si counterpart. By means of RBS, irradiated Mo x Si1‑x films with 1 keV Ar+ at normal incidence have also been used to measure experimentally the (absolute) sputtering yield and rate of Si and Mo x Si1‑x materials. The analysis reveals that, under the present working conditions, the erosion rate of silicides is larger than for silicon, supporting simulations from the TRIDYN code. This finding questions the shielding effect from silicide regions as roughening mechanism in metal-assisted nanopatterning of silicon. On the contrary, the results highlight the relevance of in situ silicide formation. Ripple formation on Mo x Si1‑x under grazing incidence is also attributed to the dominance of sputtering effects under this geometry. In conclusion, our work provides some insights into the complex morphological evolution of compound surfaces and solid experimental evidences regarding the mechanisms behind silicide-assisted nanopatterning.

Synthesis and electrochemical characterization of Silicon clathrates as anode materials for Lithium ion batteries

NASA Astrophysics Data System (ADS)

Raghavan, Rahul

Novel materials for Li-ion batteries is one of the principle thrust areas for current research in energy storage, more so than most, considering its widespread use in portable electronic gadgets and plug-in electric and hybrid cars. One of the major limiting factors in a Li-ion battery's energy density is the low specific capacities of the active materials in the electrodes. In the search for high-performance anode materials for Li-ion batteries, many alternatives to carbonaceous materials have been studied. Both cubic and amorphous silicon can reversibly alloy with lithium and have a theoretical capacity of 3500 mAh/g, making silicon a potential high density anode material. However, a large volume expansion of 300% occurs due to changes in the structure during lithium insertion, often leading to pulverization of the silicon. To this end, a class of silicon based cage compounds called clathrates are studied for electrochemical reactivity with lithium. Silicon-clathrates consist of silicon covalently bonded in cage structures comprised of face sharing Si20, Si24 and/or Si28 clusters with guest ions occupying the interstitial positions in the polyhedra. Prior to this, silicon clathrates have been studied primarily for their superconducting and thermoelectric properties. In this work, the synthesis and electrochemical characterization of two categories of silicon clathrates - Type-I silicon clathrate with aluminum framework substitution and barium guest ions (Ba8AlxSi46-x) and Type-II silicon clathrate with sodium guest ions (Nax Si136), are explored. The Type-I clathrate, Ba8AlxSi46-x consists of an open framework of aluminium and silicon, with barium (guest) atoms occupying the interstitial positions. X-ray diffraction studies have shown that a crystalline phase of clathrate is obtained from synthesis, which is powdered to a fine particle size to be used as the anode material in a Li-ion battery. Electrochemical measurements of these type of clathrates have shown that capacities comparable to graphite can be obtained for up to 10 cycles and lower capacities can be obtained for up to 20 cycles. Unlike bulk silicon, the clathrate structure does not undergo excessive volume change upon lithium intercalation, and therefore, the crystal structure is morphologically stable over many cycles. X-ray diffraction of the clathrate after cycling showed that crystallinity is intact, indicating that the clathrate does not collapse during reversible intercalation with lithium ions. Electrochemical potential spectroscopy obtained from the cycling data showed that there is an absence of formation of lithium-silicide, which is the product of lithium alloying with diamond cubic silicon. Type II silicon clathrate, NaxSi136, consists of silicon making up the framework structure and sodium (guest) atoms occupying the interstitial spaces. These clathrates showed very high capacities during their first intercalation cycle, in the range of 3,500 mAh/g, but then deteriorated during subsequent cycles. X-ray diffraction after one cycle showed the absence of clathrate phase and the presence of lithium-silicide, indicating the disintegration of clathrate structure. This could explain the silicon-like cycling behavior of Type II clathrates.

Atomic Oxygen Interactions With Silicone Contamination on Spacecraft in Low Earth Orbit Studied

NASA Technical Reports Server (NTRS)

Banks, Bruce A.

2001-01-01

Silicones have been widely used on spacecraft as potting compounds, adhesives, seals, gaskets, hydrophobic surfaces, and atomic oxygen protective coatings. Contamination of optical and thermal control surfaces on spacecraft in low Earth orbit (LEO) has been an ever-present problem as a result of the interaction of atomic oxygen with volatile species from silicones and hydrocarbons onboard spacecraft. These interactions can deposit a contaminant that is a risk to spacecraft performance because it can form an optically absorbing film on the surfaces of Sun sensors, star trackers, or optical components or can increase the solar absorptance of thermal control surfaces. The transmittance, absorptance, and reflectance of such contaminant films seem to vary widely from very transparent SiOx films to much more absorbing SiOx-based films that contain hydrocarbons. At the NASA Glenn Research Center, silicone contamination that was oxidized by atomic oxygen has been examined from LEO spacecraft (including the Long Duration Exposure Facility and the Mir space station solar arrays) and from ground laboratory LEO simulations. The findings resulted in the development of predictive models that may help explain the underlying issues and effects. Atomic oxygen interactions with silicone volatiles and mixtures of silicone and hydrocarbon volatiles produce glassy SiOx-based contaminant coatings. The addition of hydrocarbon volatiles in the presence of silicone volatiles appears to cause much more absorbing (and consequently less transmitting) contaminant films than when no hydrocarbon volatiles are present. On the basis of the LDEF and Mir results, conditions of high atomic oxygen flux relative to low contaminant flux appear to result in more transparent contaminant films than do conditions of low atomic oxygen flux with high contaminant flux. Modeling predictions indicate that the deposition of contaminant films early in a LEO flight should depend much more on atomic oxygen flux than it does later in a mission.

Method for fracturing silicon-carbide coatings on nuclear-fuel particles

DOEpatents

Turner, Lloyd J.; Willey, Melvin G.; Tiegs, Sue M.; Van Cleve, Jr., John E.

1982-01-01

This invention is a device for fracturing particles. It is designed especially for use in "hot cells" designed for the handling of radioactive materials. In a typical application, the device is used to fracture a hard silicon-carbide coating present on carbon-matrix microspheres containing nuclear-fuel material, such as uranium or thorium compounds. To promote remote control and facilitate maintenance, the particle breaker is pneumatically operated and contains no moving parts. It includes means for serially entraining the entrained particles on an anvil housed in a leak-tight chamber. The flow rate of the gas is at a value effecting fracture of the particles; preferably, it is at a value fracturing them into product particulates of fluidizable size. The chamber is provided with an outlet passage whose cross-sectional area decreases in the direction away from the chamber. The outlet is connected tangentially to a vertically oriented vortex-flow separator for recovering the product particulates entrained in the gas outflow from the chamber. The invention can be used on a batch or continuous basis to fracture the silicon-carbide coatings on virtually all of the particles fed thereto.

Device for fracturing silicon-carbide coatings on nuclear-fuel particles

DOEpatents

Turner, L.J.; Willey, M.G.; Tiegs, S.M.; Van Cleve, J.E. Jr.

This invention is a device for fracturing particles. It is designed especially for use in hot cells designed for the handling of radioactive materials. In a typical application, the device is used to fracture a hard silicon-carbide coating present on carbon-matrix microspheres containing nuclear-fuel materials, such as uranium or thorium compounds. To promote remote control and facilitate maintenance, the particle breaker is pneumatically operated and contains no moving parts. It includes means for serially entraining the entrained particles on an anvil housed in a leak-tight chamber. The flow rate of the gas is at a value effecting fracture of the particles; preferably, it is at a value fracturing them into product particulates of fluidizable size. The chamber is provided with an outlet passage whose cross-sectional area decreases in the direction away from the chamber. The outlet is connected tangentially to a vertically oriented vortex-flow separator for recovering the product particulates entrained in the gas outflow from the chamber. The invention can be used on a batch or continuous basis to fracture the silicon-carbide coatings on virtually all of the particles fed thereto.

Spectral parameters and Hamaker constants of silicon hydride compounds and organic solvents.

PubMed

Masuda, Takashi; Matsuki, Yasuo; Shimoda, Tatsuya

2009-12-15

Cyclopentasilane (CPS) and polydihydrosilane, which consist of hydrogen and silicon only, are unique materials that can be used to produce intrinsic silicon film in a liquid process, such as spin coating or an ink-jet method. Wettability and solubility of general organic solvents including the above can be estimated by Hamaker constants, which are calculated according to the Lifshitz theory. In order to calculate a Hamaker constant by the simple spectral method (SSM), it is necessary to obtain absorption frequency and function of oscillator strength in the ultraviolet region. In this report, these physical quantities were obtained by means of an optical method. As a result of examination of the relation between molecular structures and ultraviolet absorption frequencies, which were obtained from various liquid materials, it was concluded that ultraviolet absorption frequencies became smaller as electrons were delocalized. In particular, the absorption frequencies were found to be very small for CPS and polydihydrosilane due to sigma-conjugate of their electrons. The Hamaker constants of CPS and polydihydrosilane were successfully calculated based on the obtained absorption frequency and function of oscillator strength.

Formation of a 1,4-diamino-2,3-disila-1,3-butadiene derivative.

PubMed

Mondal, Kartik Chandra; Roesky, Herbert W; Dittrich, Birger; Holzmann, Nicole; Hermann, Markus; Frenking, Gernot; Meents, Alke

2013-10-30

A 1,4-diamino-2,3-disila-1,3-butadiene derivative of composition (Me2-cAAC)2(Si2Cl2) (Me2-cAAC = :C(CMe2)2(CH2)N-2,6-iPr2C6H3) was synthesized by reduction of the Me2-cAAC:SiCl4 adduct with KC8. This compound is stable at 0 °C for 3 months in an inert atmosphere. Theoretical studies reveal that the silicon atoms exhibit pyramidal coordination, where the Cl-Si-Si-Cl dihedral angle is twisted by 43.3° (calcd 45.9°). The two silicon-carbon bonds are intermediates between single and double Si-C bonds due to twisting of the C-Si-Si-C dihedral angle (163.6°).

Synthesis and thermal conductivity of type II silicon clathrates

NASA Astrophysics Data System (ADS)

Beekman, M.; Nolas, G. S.

2006-08-01

We have synthesized and characterized polycrystalline Na 1Si 136 and Na 8Si 136, compounds possessing the type II clathrate hydrate crystal structure. Resistivity measurements from 10 to 300 K indicate very large resistivities in this temperature range, with activated temperature dependences indicative of relatively large band gap semiconductors. The thermal conductivity is very low; two orders-of-magnitude lower than that of diamond-structure silicon at room temperature. The thermal conductivity of Na 8Si 136 displays a temperature dependence that is atypical of crystalline solids and more indicative of amorphous materials. This work is part of a continuing effort to explore the many different compositions and structure types of clathrates, a class of materials that continues to be of interest for scientific and technological applications.

Modification of Silicone Elastomer Surfaces with Zwitterionic Polymers: Short-Term Fouling Resistance and Triggered Biofouling Release.

PubMed

Shivapooja, Phanindhar; Yu, Qian; Orihuela, Beatriz; Mays, Robin; Rittschof, Daniel; Genzer, Jan; López, Gabriel P

2015-11-25

We present a method for dual-mode-management of biofouling by modifying surface of silicone elastomers with zwitterionic polymeric grafts. Poly(sulfobetaine methacrylate) was grafted from poly(vinylmethylsiloxane) elastomer substrates using thiol-ene click chemistry and surface-initiated, controlled radical polymerization. These surfaces exhibited both fouling resistance and triggered fouling-release functionality. The zwitterionic polymers exhibited fouling resistance over short-term (∼hours) exposure to bacteria and barnacle cyprids. The biofilms that eventually accumulated over prolonged-exposure (∼days) were easily detached by applying mechanical strain to the elastomer substrate. Such dual-functional surfaces may be useful in developing environmentally and biologically friendly coatings for biofouling management on marine, industrial, and biomedical equipment because they can obviate the use of toxic compounds.

New materials for high-energy-resolution x-ray optics

DOE PAGES

Yavas, Hasan; Sutter, John P.; Gog, Thomas; ...

2017-06-09

The use of crystals other than silicon for x-ray optics is becoming more common for many challenging experiments such as resonant inelastic x-ray scattering and nuclear resonant scattering. As more—and more specialized—spectrometers become available at many synchrotron radiation facilities, interest in pushing the limits of experimental energy resolution has increased. The potentially large improvements in resolution and efficiency that nonsilicon optics offer are beginning to be realized. Furthermore, this article covers the background and state of the art for nonsilicon crystal optics with a focus on a resolution of 10 meV or better, concentrating on compounds that form trigonal crystals,more » including sapphire, quartz, and lithium niobate, rather than the more conventional cubic materials, including silicon, diamond, and germanium.« less

Silver Coating for High-Mass-Accuracy Imaging Mass Spectrometry of Fingerprints on Nanostructured Silicon.

PubMed

Guinan, Taryn M; Gustafsson, Ove J R; McPhee, Gordon; Kobus, Hilton; Voelcker, Nicolas H

2015-11-17

Nanostructure imaging mass spectrometry (NIMS) using porous silicon (pSi) is a key technique for molecular imaging of exogenous and endogenous low molecular weight compounds from fingerprints. However, high-mass-accuracy NIMS can be difficult to achieve as time-of-flight (ToF) mass analyzers, which dominate the field, cannot sufficiently compensate for shifts in measured m/z values. Here, we show internal recalibration using a thin layer of silver (Ag) sputter-coated onto functionalized pSi substrates. NIMS peaks for several previously reported fingerprint components were selected and mass accuracy was compared to theoretical values. Mass accuracy was improved by more than an order of magnitude in several cases. This straightforward method should form part of the standard guidelines for NIMS studies for spatial characterization of small molecules.

Enhancement of optical absorption of Si (100) surfaces by low energy N+ ion beam irradiation

NASA Astrophysics Data System (ADS)

Bhowmik, Dipak; Karmakar, Prasanta

2018-05-01

The increase of optical absorption efficiency of Si (100) surface by 7 keV and 8 keV N+ ions bombardment has been reported here. A periodic ripple pattern on surface has been observed as well as silicon nitride is formed at the ion impact zones by these low energy N+ ion bombardment [P. Karmakar et al., J. Appl. Phys. 120, 025301 (2016)]. The light absorption efficiency increases due to the presence of silicon nitride compound as well as surface nanopatterns. The Atomic Force Microscopy (AFM) study shows the formation of periodic ripple pattern and increase of surface roughness with N+ ion energy. The enhancement of optical absorption by the ion bombarded Si, compared to the bare Si have been measured by UV - visible spectrophotometer.

Organics in water contamination analyzer, phase 1

NASA Technical Reports Server (NTRS)

1986-01-01

The requirements which would result in identifying the components of an automatic analytical system for the analysis of specific organic compounds in the space station potable water supply are defined. The gas chromatographic system for such an analysis is limited to commercially available off-the-shelf hardware and includes the sample inlet, an ionization detector, capillary columns as well as computerized compound identification. The sampling system will be a special variation of the purge and trap Tenax mode using six-port valves and a 500 microliter water sample. Capillary columns used for the separating of contaminants will be bonded phase fused silica with a silicone stationary phase. Two detectors can be used: photoionization and far ultraviolet, since they are sensitive and compatible with capillary columns. A computer system evaluation and program with the principle of compound identification based on the retention index is presented.

Development of Bushing Compounds for Tracked Vehicles

DTIC Science & Technology

1990-10-01

unwanted stepchild - part of called anti patented NBR -12 formulation the family (system), but devoid of needed indicated that service life could be...as Development and Engineering Center’s long. Bushings currently used in the M I track Rubber and Coated Fabrics Research Group assembly typically fail...formulations of should be improved. Numerous selected candidate natural rubber , propylene formulations-based on natural rubber , oxide, and silicone

Nonconsumable electrode assembly and use thereof for the electrolytic production of metals and silicon

DOEpatents

Byrne, Stephen C.; Ray, Siba P.

1984-01-01

A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor attached to a ceramic electrode body by a metal bond on a portion of the body having a level of free metal or metal alloy sufficient to effect a metal bond.

Corrosion Preventative Compounds (CPCs) Effect on Aircraft Electrical Wiring Components

DTIC Science & Technology

2011-08-01

NOTES Focused Workshop on Cadmium Plating Alternatives, August 30-31, 2011, Baltimore, MD. Sponsored by SERDP/ESTCP. 14. ABSTRACT 15. SUBJECT...prepared by the Wiring Interconnections Laboratory of the Raytheon Technical Services Company LLC, Indianapolis, Indiana . Support of this investigation...MIL-DTL-38999 Series III, Class W A Cadmium (over suitable underplate) plated aluminum, silicone grommets and epoxy inserts MIL-DTL-38999 Series

Baseline tests of the AM General DJ-5E electruck electric delivery van

NASA Technical Reports Server (NTRS)

Dustin, M. O.; Tryon, H. B.; Sargent, N. B.

1977-01-01

An electric quarter ton truck designed for use as a postal delivery vehicle was tested to characterize the state of the art of electric vehicles. Vehicle performance test results are presented. It is powered by a single-module, 54 volt industrial battery through a silicon controlled rectifier continuously adjustable controller with regenerative braking applied to a direct current compound wound motor.

New Nitration Concepts

DTIC Science & Technology

1987-09-01

CIECLASSiPCAflON DOWNGRAAING SCHEDULE d is trib ut ion unlimited N/A _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 4 PERFORM!NG ORGANIZATION REPORT NUMBER(S) s. moio OGNZTON...substitute nitroso for silicon by reaction of the silylated compound with nitrosonium fluoroborate but time and funding did not permit completion of...acetylenes, 10.8,9 The synthesis is achieved by treating a bis-substituted trialkylsilyl- acetylene with a nitronium ion 3ource (i.e., nitronium tetrafluoro

Materials investigation and tests for the development of space compatible electrical connectors

NASA Technical Reports Server (NTRS)

Pomeroy, C.; Mccabe, T.

1971-01-01

A molding study of compounds based on copolymers of highly fluorinated olefins and of flame retardant silicone is reported. Both single cavity and four cavity molds having size 22 and 24 holes with three webs in each hole were used. Also covered are dielectric strength, arc resistance, Bashore rebound, and maintenance aging tests on the various materials that have been successfully molded.

Thermophysical Properties of Matter - the TPRC Data Series. Volume 12. Thermal Expansion Metallic Elements and Alloys

DTIC Science & Technology

1975-01-01

the thermal expansion of metallic elements, alloys, and intermetallic compounds. We believe there is also much food for reflection by the specialist...24 39 Plutonium Pu ........ ............... 260 40’ t Polonium Po ..... ............... 270 41* Potassium K ..... ............... 271 42...923 209 NIckel-Palladium NI-Pd..................926 210 * Nickel-Pitaum Ni-Pt.................90 211 Nickel-Silicon NI-SI.................932 212

METHOD OF INCREASING THE DISPERSIBILITY OF SLURRY PARTICLES

DOEpatents

McBride, J.P.

1959-12-15

A method is described for increasing the dispersibility of metallic oxide particles, particularly thorium oxide, in slurries. Organo-silicon compounds, such as organosilicon halides and silicate esters, are deposited on the surface of the oxide particles. A firing step conducted at temperatures of 600 to 1200 deg C removes the organic groups leaving a surface coating of silica, which provides the desired increase in particle dispersibility.

Carbonation of Clay Minerals Exposed to scCO2/Water at 200 degrees and 250 degrees C

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

Sugama, T.; Ecker, L.; Gill, S.

2010-11-01

To clarify the mechanisms of carbonation of clay minerals, such as bentonite, kaolinite, and soft clay, we exposed them to supercritical carbon dioxide (scCO2)/water at temperatures of 200 and 250 C and pressures of 1500 and 2000 psi for 72- and 107-hours. Bentonite, comprising three crystalline phases, montmorillonite (MMT), anorthoclase-type albite, and quartz was susceptible to reactions with ionic carbonic acid yielded by the interactions between scCO2 and water, particularly MMT and anorthoclase-type albite phases. For MMT, the cation-exchangeable ions, such as Na+ and Ca2+, present in its basal interplanar space, were replaced by proton, H+, from ionic carbonic acid;more » thereafter, the cations leaching from MMT directly reacted with CO32- as a counter ion of H+ to form carbonate compounds. Such in-situ carbonation process in basal space caused the shrinkage and breakage of the spacing structure within MMT. In contrast, the wet carbonation of anorthoclase-type albite, categorized as rock minerals, entailed the formation of three amorphous by-products, such as carbonates, kaolinite-like compounds, and silicon dioxide. Together, these two different carbonations caused the disintegration and corruption of bentonite. Kaolinite clay containing the amorphous carbonates and silicon dioxide was inert to wet carbonation. We noted only a gain in weight due to its water uptake, suggesting that kaolinite-like by-products generated by the wet carbonation of rock minerals might remain unchanged even during extended exposure. Soft clay consisting of two crystalline phases, dolomite and silicon dioxide, also was unaltered by wet carbonation, despite the uptake of water.« less

Immobilization of kojic acid in ZnAl-hydrotalcite like compounds

NASA Astrophysics Data System (ADS)

Ambrogi, Valeria; Perioli, Luana; Nocchetti, Morena; Latterini, Loredana; Pagano, Cinzia; Massetti, Elena; Rossi, Carlo

2012-01-01

Kojic acid (KOJ) is a melanin synthesis inhibitor widely used as skin lightening agent in topical preparations. Unfortunately it is easily susceptible to photo-oxidation, phenomenon responsible for chemical and organoleptic modifications. The aim of this work was the intercalation of KOJ in hydrotalcite-like compounds (HTlc) in order to stabilize KOJ and to reduce its photolability. Hydrotalcite containing Zn and Al (ZnAl-HTlc) was used as host to obtain the final compound ZnAl-HTlc-KOJ. The intercalation was carried out, after many attempts, by ionic exchange mechanism by means of the strong base EtO- in anhydrous ethanol/dimethylsulfoxide (DMSO) mixture as solvent in order to generate KOJ- anions. The final product was characterized by the X-ray powder diffraction (XRPD), FT-IR spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and elemental analysis. The intercalated compound was formulated in a siliconic water free self-emulsifying ointment and the in vitro release profile was evaluated. All samples (intercalation compound and its formulation) were submitted also to spectrophotometric assays in order to evaluate the matrix protective effect towards ultraviolet rays.

PAH toxicity at aqueous solubility in the fish embryo test with Danio rerio using passive dosing.

PubMed

Seiler, Thomas-Benjamin; Best, Nina; Fernqvist, Margit Møller; Hercht, Hendrik; Smith, Kilian E C; Braunbeck, Thomas; Mayer, Philipp; Hollert, Henner

2014-10-01

As part of the risk assessment process within REACh, prior to manufacturing and distribution of chemical substances their (eco)toxicological impacts have to be investigated. The fish embryo toxicity test (FET) with the zebrafish Danio rerio has gained a high significance as an in vitro alternative to animal testing in (eco)toxicology. However, for hydrophobic organic chemicals it remains a technical challenge to ensure constant freely dissolved concentration at the maximum exposure level during such biotests. Passive dosing with PDMS silicone was thus applied to control the freely dissolved concentration of ten PAHs at their saturation level in the FET. The experiments gave repeatable results, with the toxicity of the PAHs generally increasing with the maximum chemical activities of the PAHs. HPLC analysis confirmed constant exposure at the saturation level. In additional experiments, fish embryos without direct contact to the silicone surface showed similar mortalities as those exposed with direct contact to the silicone. Silicone oil overlaying the water phase as a novel passive dosing phase had no observable effects on the development of the fish embryos until hatching. This study provides further data to support the close relationship between the chemical activity and the toxicity of hydrophobic organic compounds. Passive dosing from PDMS silicone enabled reliable toxicity testing of (highly) hydrophobic substances at aqueous solubility, providing a practical way to control toxicity exactly at the maximum exposure level. This approach is therefore expected to be useful as a cost-effective initial screening of hydrophobic chemicals for potential adverse effects to freshwater vertebrates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Bio-inspired hemispherical compound eye camera

NASA Astrophysics Data System (ADS)

Xiao, Jianliang; Song, Young Min; Xie, Yizhu; Malyarchuk, Viktor; Jung, Inhwa; Choi, Ki-Joong; Liu, Zhuangjian; Park, Hyunsung; Lu, Chaofeng; Kim, Rak-Hwan; Li, Rui; Crozier, Kenneth B.; Huang, Yonggang; Rogers, John A.

2014-03-01

Compound eyes in arthropods demonstrate distinct imaging characteristics from human eyes, with wide angle field of view, low aberrations, high acuity to motion and infinite depth of field. Artificial imaging systems with similar geometries and properties are of great interest for many applications. However, the challenges in building such systems with hemispherical, compound apposition layouts cannot be met through established planar sensor technologies and conventional optics. We present our recent progress in combining optics, materials, mechanics and integration schemes to build fully functional artificial compound eye cameras. Nearly full hemispherical shapes (about 160 degrees) with densely packed artificial ommatidia were realized. The number of ommatidia (180) is comparable to those of the eyes of fire ants and bark beetles. The devices combine elastomeric compound optical elements with deformable arrays of thin silicon photodetectors, which were fabricated in the planar geometries and then integrated and elastically transformed to hemispherical shapes. Imaging results and quantitative ray-tracing-based simulations illustrate key features of operation. These general strategies seem to be applicable to other compound eye devices, such as those inspired by moths and lacewings (refracting superposition eyes), lobster and shrimp (reflecting superposition eyes), and houseflies (neural superposition eyes).

Extraction tools for identification of chemical contaminants in estuarine and coastal waters to determine toxic pressure on primary producers.

PubMed

Booij, Petra; Sjollema, Sascha B; Leonards, Pim E G; de Voogt, Pim; Stroomberg, Gerard J; Vethaak, A Dick; Lamoree, Marja H

2013-09-01

The extent to which chemical stressors affect primary producers in estuarine and coastal waters is largely unknown. However, given the large number of legacy pollutants and chemicals of emerging concern present in the environment, this is an important and relevant issue that requires further study. The purpose of our study was to extract and identify compounds which are inhibitors of photosystem II activity in microalgae from estuarine and coastal waters. Field sampling was conducted in the Western Scheldt estuary (Hansweert, The Netherlands). We compared four different commonly used extraction methods: passive sampling with silicone rubber sheets, polar organic integrative samplers (POCIS) and spot water sampling using two different solid phase extraction (SPE) cartridges. Toxic effects of extracts prepared from spot water samples and passive samplers were determined in the Pulse Amplitude Modulation (PAM) fluorometry bioassay. With target chemical analysis using LC-MS and GC-MS, a set of PAHs, PCBs and pesticides was determined in field samples. These compound classes are listed as priority substances for the marine environment by the OSPAR convention. In addition, recovery experiments with both SPE cartridges were performed to evaluate the extraction suitability of these methods. Passive sampling using silicone rubber sheets and POCIS can be applied to determine compounds with different structures and polarities for further identification and determination of toxic pressure on primary producers. The added value of SPE lies in its suitability for quantitative analysis; calibration of passive samplers still needs further investigation for quantification of field concentrations of contaminants. Copyright © 2013 Elsevier Ltd. All rights reserved.

Clathrate compounds and method of manufacturing

DOEpatents

Nolas, George S [Tampa, FL; Witanachchi, Sarath [Tampa, FL; Mukherjee, Pritish [Tampa, FL

2009-05-19

The present invention comprises new materials, material structures, and processes of fabrication of such that may be used in technologies involving the conversion of light to electricity and/or heat to electricity, and in optoelectronics technologies. The present invention provide for the fabrication of a clathrate compound comprising a type II clathrate lattice with atoms of silicon and germanium as a main framework forming lattice spacings within the framework, wherein the clathrate lattice follows the general formula Si.sub.136-yGe.sub.y, where y indicates the number of Ge atoms present in the main framework and 136-y indicates the number of Si atoms present in the main framework, and wherein y>0.

Thin Film Composite Materials, Phase 2

DTIC Science & Technology

1987-01-01

were Kevlar coated with silicone, EPDM , or neoprene rubber , with the following results: 1. Tensile testing of coated Kevlar fabric is very difficult...Monte, CA, but the samples were not large enough for our testing program. e. EPDM . This is a rubber compound which consists of ;n ethylene propylene...materials. 2. A method was developed for measuring water vapor permeability. Neoprene and EPDM are promising as coatings with good water resistance; however

Reactions of Hydrogen Chloride and Boron Trichloride with Trimethylsilylamino Groups

DTIC Science & Technology

1989-04-04

SUPPLEMENTARY NOTATION 17, COSATI CODES 18. SUBJECT TERMS (Continue on reverse if necessary and kientify by block number) FIELD ,,GROUP SU8 -GROUP...nitride preceramic polymers . Due to the low yield multistage synthesis, alternate routes to isomeric compositions and intermediates needed to be...Organo- metallic Polymers , Zeldin, M., Wynne, K. J., Allcock, H. R.; Ed, ACS Symposium Series 360. (4) Ebsworth, E.A.V. Volatile Silicon Compounds

Effects of Processing on MOS Radiation Hardening

DTIC Science & Technology

1992-09-01

magnitude) impurity inclusion for Fluorine sources vs. Chlorine sources, many of the other beneficial effects on point defects, traps, MOS quality, etc...profiles. The addition of percent concentrations of a chlorine rates from 1 to 10 ml/nmr. This corresponded to fluorine bearing compound to the silicon...computes the partial roethane and gaseous nitrogen trifluoride . The alphatic liq- pres-ures of all the possible species in equilibrium in the uid

Optical and Electrical Characterization of Multiply Doped Silicon: A Study of the Si:(In, A1) System.

DTIC Science & Technology

1984-02-01

RFWAL-TR-83-4108 UNCLASSIFIED F33 5-8i--50 5 S F/ 2/12 NL Lmmhhhhml 1.2 11. . .4 ’sqo ItI -.9 .9 D’ ’-3.,= 1111 III1 ,1 MICROCOP REOUTO TES3 AR...is compatible with conventional charge-coupled device (CCD) signal processing, dopant and impurity uniformity is inherently superior to compound

Polyimides containing pendent siloxane groups

NASA Technical Reports Server (NTRS)

Connell, John W. (Inventor); St.clair, Terry L. (Inventor); Hergenrother, Paul M. (Inventor)

1994-01-01

Novel polyimides containing pendent siloxane groups (PISOX) were prepared by the reaction of functionalized siloxane compounds with hydroxy containing polyimides (PIOH). The pendent siloxane groups on the polyimide backbone offer distinct advantages such as lowering the dielectric constant and moisture resistance and enhanced atomic oxygen resistance. The siloxane containing polyimides are potentially useful as protective silicon oxide coatings and are useful for a variety of applications where atomic oxygen resistance is needed.

Development of organic non-flammable spacecraft potting, encapsulating and conformal coating compounds

NASA Technical Reports Server (NTRS)

Lieberman, S. L.

1971-01-01

The overall program objective was to develop a flexible compound which not only functioned in a manned aerospace environment as an effective electrical insulation, but whose flammability characteristics in 16.5 psia, 60% oxygen/40% nitrogen were evidenced by rapid self-extinguishment and minimal thermal (pyrolysis) degradation. The following polymeric matrices were examined in depth: fluoroelastomers, modified fluoroelastomers, silicone RTV's, and modified silicone and fluorosilicone RTV's. Almost none of these systems burned in air, but all burned in 6.2 psia oxygen. Inorganic, organic, and inorganic/organic additives were evaluated in conjunction with these polymers in order to achieve the required survival in the 16.5 psia 60/40 environment. Depending upon formulations, it was possible to achieve nonflammable products when tested in the 1/4 in. x 1/4 in. x 1 in. configuration, even up to and including 16.5 psia oxygen. However, in order to assure this level of flame resistance, it was found necessary to heavily load the matrix with the additives. This resulted in a significant reduction in mechanical properties and large increases in viscosities. Optimization of formulations to obtain a suitable balance between these properties and flammability resistance led to the final selection of Formulation 387 as the primary system.

Synthesis, crystal structure, and magnetic properties of novel intermetallic compounds R2Co2SiC (R = Pr, Nd).

PubMed

Zhou, Sixuan; Mishra, Trinath; Wang, Man; Shatruk, Michael; Cao, Huibo; Latturner, Susan E

2014-06-16

The intermetallic compounds R2Co2SiC (R = Pr, Nd) were prepared from the reaction of silicon and carbon in either Pr/Co or Nd/Co eutectic flux. These phases crystallize with a new stuffed variant of the W2CoB2 structure type in orthorhombic space group Immm with unit cell parameters a = 3.978(4) Å, b = 6.094(5) Å, c = 8.903(8) Å (Z = 2; R1 = 0.0302) for Nd2Co2SiC. Silicon, cobalt, and carbon atoms form two-dimensional flat sheets, which are separated by puckered layers of rare-earth cations. Magnetic susceptibility measurements indicate that the rare earth cations in both analogues order ferromagnetically at low temperature (TC ≈ 12 K for Nd2Co2SiC and TC ≈ 20 K for Pr2Co2SiC). Single-crystal neutron diffraction data for Nd2Co2SiC indicate that Nd moments initially align ferromagnetically along the c axis around ∼12 K, but below 11 K, they tilt slightly away from the c axis, in the ac plane. Electronic structure calculations confirm the lack of spin polarization for Co 3d moments.

Silicone rod extraction followed by liquid desorption-large volume injection-programmable temperature vaporiser-gas chromatography-mass spectrometry for trace analysis of priority organic pollutants in environmental water samples.

PubMed

Delgado, Alejandra; Posada-Ureta, Oscar; Olivares, Maitane; Vallejo, Asier; Etxebarria, Nestor

2013-12-15

In this study a priority organic pollutants usually found in environmental water samples were considered to accomplish two extraction and analysis approaches. Among those compounds organochlorine compounds, pesticides, phthalates, phenols and residues of pharmaceutical and personal care products were included. The extraction and analysis steps were based on silicone rod extraction (SR) followed by liquid desorption in combination with large volume injection-programmable temperature vaporiser (LVI-PTV) and gas chromatography-mass spectrometry (GC-MS). Variables affecting the analytical response as a function of the programmable temperature vaporiser (PTV) parameters were firstly optimised following an experimental design approach. The SR extraction and desorption conditions were assessed afterwards, including matrix modification, time extraction, and stripping solvent composition. Subsequently, the possibility of performing membrane enclosed sorptive coating extraction (MESCO) as a modified extraction approach was also evaluated. The optimised method showed low method detection limits (3-35 ng L(-1)), acceptable accuracy (78-114%) and precision values (<13%) for most of the studied analytes regardless of the aqueous matrix. Finally, the developed approach was successfully applied to the determination of target analytes in aqueous environmental matrices including estuarine and wastewater samples. © 2013 Elsevier B.V. All rights reserved.

Chemical screening identifies filastatin, a small molecule inhibitor of Candida albicans adhesion, morphogenesis, and pathogenesis.

PubMed

Fazly, Ahmed; Jain, Charu; Dehner, Amie C; Issi, Luca; Lilly, Elizabeth A; Ali, Akbar; Cao, Hong; Fidel, Paul L; Rao, Reeta P; Kaufman, Paul D

2013-08-13

Infection by pathogenic fungi, such as Candida albicans, begins with adhesion to host cells or implanted medical devices followed by biofilm formation. By high-throughput phenotypic screening of small molecules, we identified compounds that inhibit adhesion of C. albicans to polystyrene. Our lead candidate compound also inhibits binding of C. albicans to cultured human epithelial cells, the yeast-to-hyphal morphological transition, induction of the hyphal-specific HWP1 promoter, biofilm formation on silicone elastomers, and pathogenesis in a nematode infection model as well as alters fungal morphology in a mouse mucosal infection assay. We term this compound filastatin based on its strong inhibition of filamentation, and we use chemical genetic experiments to show that it acts downstream of multiple signaling pathways. These studies show that high-throughput functional assays targeting fungal adhesion can provide chemical probes for study of multiple aspects of fungal pathogenesis.

Chemical screening identifies filastatin, a small molecule inhibitor of Candida albicans adhesion, morphogenesis, and pathogenesis

PubMed Central

Fazly, Ahmed; Jain, Charu; Dehner, Amie C.; Issi, Luca; Lilly, Elizabeth A.; Ali, Akbar; Cao, Hong; Fidel, Paul L.; P. Rao, Reeta; Kaufman, Paul D.

2013-01-01

Infection by pathogenic fungi, such as Candida albicans, begins with adhesion to host cells or implanted medical devices followed by biofilm formation. By high-throughput phenotypic screening of small molecules, we identified compounds that inhibit adhesion of C. albicans to polystyrene. Our lead candidate compound also inhibits binding of C. albicans to cultured human epithelial cells, the yeast-to-hyphal morphological transition, induction of the hyphal-specific HWP1 promoter, biofilm formation on silicone elastomers, and pathogenesis in a nematode infection model as well as alters fungal morphology in a mouse mucosal infection assay. We term this compound filastatin based on its strong inhibition of filamentation, and we use chemical genetic experiments to show that it acts downstream of multiple signaling pathways. These studies show that high-throughput functional assays targeting fungal adhesion can provide chemical probes for study of multiple aspects of fungal pathogenesis. PMID:23904484

Tuning negative differential resistance in single-atomic layer boron-silicon sheets

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

Zhou, Ming-Yue; Liu, Chun-Sheng, E-mail: csliu@njupt.edu.cn, E-mail: yanxh@njupt.edu.cn; Key Laboratory of Radio Frequency and Micro-Nano Electronics of Jiangsu Province, Nanjing 210023, Jiangsu

2015-03-21

Using density functional theory and nonequilibrium Green's function formalism for quantum transport calculation, we have quantified the ballistic transport properties along different directions in two-dimensional boron-silicon (B-Si) compounds, as well as the current response to bias voltage. The conductance of the most B-Si devices is higher than the conductance of one-atom-thick boron and silicene. Furthermore, the negative differential resistance phenomenon can be found at certain B-Si stoichiometric composition, and it occurs at various bias voltages. Also, the peak-to-valley ratio is sensitive to the B-Si composition and dependent of the direction considered for B-Si monolayers. The present findings could be helpfulmore » for applications of the single-atomic layer B-Si sheets in the field of semiconductor devices or low-dimensional electronic devices.« less

Silicon Utilizing Microbial Bioactivities in the Biosphere

NASA Astrophysics Data System (ADS)

Sen, M. M.; Das, S.

2012-12-01

Diatoms are unicellular eukaryotic algae and an important member of the silicon utilizing organisms, that generate ~20% of the ~100 billion metric tons of organic carbon produced through photosynthesis on Earth each year. Fragilariopsis is a dominating psychrophilic diatom genus in polar sea ice. The two species Fragilariopsis cylindrus and Fragilariopsis curta are able to grow and divide below freezing temperature. Antifreeze proteins (AFPs), involved in cold adaptation in several psychrophilic organisms, are widespread in this two polar species. Achanthes minutissima isolated as dominant diatom has degradable effects involving petroleum hydocarbons. Phaeodactylum tricornutum, have antibacterial activity and the fatty acid, eicosapentaenoic acid (EPA), has been identified as one compound responsible for this activity. Other antibacterial compounds are monounsaturated fatty acid (9Z)-hexadecenoic acid (palmitoleic acid; C16:1 n-7) and the relatively unusual polyunsaturated fatty acid (6Z, 9Z, 12Z)-hexadecatrienoic acid (HTA; C16:3 n-4). Both are active against Gram-positive bacteria and many Gram-negative pathogen. Palmitoleic acid is active at micro-molar concentrations, kills bacteria rapidly, and is highly active against multidrug-resistant Staphylococcus aureus. Domoic acid -a neurotoxin produced by Pseudo-nitzschia accumulates in marine invertebrates. Evidences of sea lion (Zalophus californianus) and human poisoning following consumption of contaminated blue mussels (Mytilus edulis) is mainly due to this toxin. Among the most prominent features described in human beings was memory impairment which led to the name Amnesic Shellfish Poisoning [ASP]. Silicon utilizing organisms can act as a bioindicator of environmental contamination, thus a rapid change in phytochelatins to both the increase in and the withdrawal of environmental Cd stress was found in Thalassiosira nordenskioeldii. Some of them also can produce biofuels particularly diatoms have significant potential as a source of biomass for the production of biofuels, due to their high growth rates and high cellular lipid content. Petroleum pollutant degradation can also be done by these organisms-Achanthes minutissima has degradable effects involving petroleum hydocarbons. Stephanopyxis turris a silicon utilizing organism releases a blend of chlorinated C8 hydrocarbons. This adds a fundamentally new pathway to the limited set of halogenating enzymatic activities known from nature. Many silicon utilizing organisms can produce PUFA from saturated fatty acids which ultimately produce many important bioactive chemicals like hormosirene, finaverrene, heptadienal, dietyopterene, cystophorene, decadienal. Trienoic acid, octadiene and many other important agents. Similarly terpenoid biosynthetic pathway is activated by them with formation of diterpenoids, sesterpenoids, triterpenoids and sterols.

Unraveling Crystalline Structure of High-Pressure Phase of Silicon Carbonate

NASA Astrophysics Data System (ADS)

Zhou, Rulong; Qu, Bingyan; Dai, Jun; Zeng, Xiao Cheng

2014-03-01

Although CO2 and SiO2 both belong to group-IV oxides, they exhibit remarkably different bonding characteristics and phase behavior at ambient conditions. At room temperature, CO2 is a gas, whereas SiO2 is a covalent solid with rich polymorphs. A recent successful synthesis of the silicon-carbonate solid from the reaction between CO2 and SiO2 under high pressure [M. Santoro et al., Proc. Natl. Acad. Sci. U.S.A. 108, 7689 (2011)] has resolved a long-standing puzzle regarding whether a SixC1-xO2 compound between CO2 and SiO2 exists in nature. Nevertheless, the detailed atomic structure of the SixC1-xO2 crystal is still unknown. Here, we report an extensive search for the high-pressure crystalline structures of the SixC1-xO2 compound with various stoichiometric ratios (SiO2:CO2) using an evolutionary algorithm. Based on the low-enthalpy structures obtained for each given stoichiometric ratio, several generic structural features and bonding characteristics of Si and C in the high-pressure phases are identified. The computed formation enthalpies show that the SiC2O6 compound with a multislab three-dimensional (3D) structure is energetically the most favorable at 20 GPa. Hence, a stable crystalline structure of the elusive SixC1-xO2 compound under high pressure is predicted and awaiting future experimental confirmation. The SiC2O6 crystal is an insulator with elastic constants comparable to typical hard solids, and it possesses nearly isotropic tensile strength as well as extremely low shear strength in the 2D plane, suggesting that the multislab 3D crystal is a promising solid lubricant. These valuable mechanical and electronic properties endow the SiC2O6 crystal for potential applications in tribology and nanoelectronic devices, or as a stable solid-state form for CO2 sequestration.

Melting of SiC powders preplaced duplex stainless steel using TIG welding

NASA Astrophysics Data System (ADS)

Maleque, M. A.; Afiq, M.

2018-01-01

TIG torch welding technique is a conventional melting technique for the cladding of metallic materials. Duplex stainless steels (DSS) show decrease in performance under aggressive environment which may lead to unanticipated failure due to poor surface properties. In this research, surface modification is done by using TIG torch method where silicon carbide (SiC) particles are fused into DSS substrate in order to form a new intermetallic compound at the surface. The effect of particle size, feed rate of SiC preplacement, energy input and shielding gas flow rate on surface topography, microstructure, microstructure and hardness are investigated. Deepest melt pool (1.237 mm) is produced via TIG torch with highest energy input of 1080 J/mm. Observations of surface topography shows rippling marks which confirms that re-solidification process has taken place. Melt microstructure consist of dendritic and globular carbides precipitate as well as partially melted silicon carbides (SiC) particles. Micro hardness recorded at value ranging from 316 HV0.5 to 1277 HV0.5 which shows increment from base hardness of 260 HV0.5kgf. The analyzed result showed that incorporation of silicon carbide particles via TIG Torch method increase the hardness of DSS.

Hydroalumination of a chlorotrialkynylsilane: spontaneous stepwise 1,3-dyotropic rearrangement via an intermediate silyl cation.

PubMed

Uhl, Werner; Bohnemann, Jörg; Layh, Marcus; Würthwein, Ernst-Ulrich

2014-07-07

A new functionalised alkynylsilane, Cl-Si(CC-CMe3 )3 (3), was obtained by a facile multistep synthesis. Treatment of 3 with equimolar quantities of the hydrides H-M(CMe3 )2 (M=Al, Ga) gave the mixed alkenyl-di(alkynyl)silanes, in which the chlorine atom adopts a bridging position between the aluminium and silicon atoms. Dual hydrogallation of 3 resulted in the formation of a di(alkenyl)-alkynylsilane containing two gallium atoms, one of which is coordinated to the chlorine atom, and the second is bonded to the α-carbon atom of the remaining alkynyl group. A tert-butylsilane was unexpectedly formed by a unique 1,3-dyotropic chlorine-tert-butyl exchange for the corresponding dialuminium compound. One aluminium atom is bonded to a tert-butyl group, a terminal chlorine atom and the α-carbon atom of the ethynyl moiety; the second is coordinatively unsaturated, with two terminal tert-butyl substituents. High-level quantum-chemical calculations favour a stepwise dyotropic rearrangement with an intermediate cationic silicon species over a simultaneous tert-butyl-chlorine migration via a five-coordinate silicon atom in the transition state. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Desorption of biocides from renders modified with acrylate and silicone.

PubMed

Styszko, Katarzyna; Bollmann, Ulla E; Wangler, Timothy P; Bester, Kai

2014-01-01

Biocides are used in the building industry to prevent algal, bacterial and fungal growth on polymericrenders and thus to protect buildings. However, these biocides are leached into the environment. To better understand this leaching, the sorption/desorption of biocides in polymeric renders was assessed. In this study the desorption constants of cybutryn, carbendazim, iodocarb, isoproturon, diuron, dichloro-N-octylisothiazolinone and tebuconazole towards acrylate and silicone based renders were assessed at different pH values. At pH 9.5 (porewater) the constants for an acrylate based render varied between 8 (isoproturon) and 9634 (iodocarb) and 3750 (dichloro-N-octylisothiazolinone), respectively. The values changed drastically with pH value. The results for the silicone based renders were in a similar range and usually the compounds with high sorption constants for one polymer also had high values for the other polymer. Comparison of the octanol water partitioning constants (Kow) with the render/water partitioning constants (Kd) revealed similarities, but no strong correlation. Adding higher amounts of polymer to the render material changed the equilibria for dichloro-N-octylisothiazolinone, tebuconazole, cybutryn, carbendazim but not for isoproturon and diuron. Copyright © 2013 Elsevier Ltd. All rights reserved.

Thin film GaP for solar cell application

NASA Astrophysics Data System (ADS)

Morozov, I. A.; Gudovskikh, A. S.; Kudryashov, D. A.; Nikitina, E. V.; Kleider, J.-P.; Myasoedov, A. V.; Levitskiy, V.

2016-08-01

A new approach to the silicon based heterostructures technology consisting of the growth of III-V compounds (GaP) on a silicon substrate by low-temperature plasma enhanced atomic layer deposition (PE-ALD) is proposed. The basic idea of the method is to use a time modulation of the growth process, i.e. time separated stages of atoms or precursors transport to the growing surface, migration over the surface, and crystal lattice relaxation for each monolayer. The GaP layers were grown on Si substrates by PE-ALD at 350°C with phosphine (PH3) and trimethylgallium (TMG) as sources of III and V atoms. Scanning and transmission electron microscopy demonstrate that the grown GaP films have homogeneous amorphous structure, smooth surface and a sharp GaP/Si interface. The GaP/Si heterostructures obtained by PE-ALD compare favourably to that conventionally grown by molecular beam epitaxy (MBE). Indeed, spectroscopic ellipsometry measurements indicate similar interband optical absorption while photoluminescence measurements indicate higher charge carrier effective lifetime. The better passivation properties of GaP layers grown by PE-ALD demonstrate a potential of this technology for new silicon based photovoltaic heterostructure

A new electrochemical sensor for the simultaneous determination of acetaminophen and codeine based on porous silicon/palladium nanostructure.

PubMed

Ensafi, Ali A; Ahmadi, Najmeh; Rezaei, Behzad; Abarghoui, Mehdi Mokhtari

2015-03-01

A porous silicon/palladium nanostructure was prepared and used as a new electrode material for the simultaneous determination of acetaminophen (ACT) and codeine (COD). Palladium nanoparticles were assembled on porous silicon (PSi) microparticles by a simple redox reaction between the Pd precursor and PSi in an aqueous solution of hydrofluoric acid. This novel nanostructure was characterized by different spectroscopic and electrochemical techniques including scanning electron microscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, fourier transform infrared spectroscopy and cyclic voltammetry. The high electrochemical activity, fast electron transfer rate, high surface area and good antifouling properties of this nanostructure enhanced the oxidation peak currents and reduced the peak potentials of ACT and COD at the surface of the proposed sensor. Simultaneous determination of ACT and COD was explored using differential pulse voltammetry. A linear range of 1.0-700.0 µmol L(-1) was achieved for ACT and COD with detection limits of 0.4 and 0.3 µmol L(-1), respectively. Finally, the proposed method was used for the determination of ACT and COD in blood serum, urine and pharmaceutical compounds. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis and properties of SiN coatings as stable fluorescent markers on vertically aligned carbon nanofibers

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

Pearce, Ryan; Klein, Kate L; Ivanov, Ilia N

2014-01-01

The growth of vertically aligned carbon nanofibers (VACNFs) in a catalytic dc ammonia/acetylene plasma process on silicon substrates is often accompanied by sidewall deposition of material that contains mostly Si and N. In fluorescent microscopy experiments, imaging VACNF interfacing to live cell cultures it turned out that this material is broadly fluorescent, which made VACNFs useful as spatial markers, or created nuisance when DNA-labeling got masked. In this paper we provide insight into nature of this silicon/nitrogen in situ coatings. Here we have proposed a potential mechanism for deposition of SiNx coating on the sidewalls of VACNFs during PECVD synthesismore » in addition to exploring the origin of the coatings fluorescence. It seems most likely that the substrate reacts with the process gases through both processes similar to reactive sputtering and CVD to form silane and other silicon bearing compounds before being deposited isotropically as a SiNx coating onto the VACNFs. The case for the presence of Si-NCs is made strong through a combination of the strong fluorescence and elemental analysis of the samples. These broadly luminescent fibers can prove useful as registry markers in fluorescent cellular studies.« less

The measurement of alpha particle emissions from semiconductor memory materials

NASA Astrophysics Data System (ADS)

Bouldin, D. P.

1981-07-01

With the increasing concern for the affects of alpha particles on the reliability of semiconductor memories, an interest has arisen in characterizing semiconductor manufacturing materials for extremely low-level alpha-emitting contaminants. It is shown that four elements are of primary concern: uranium, thorium, radium, and polonium. Measurement of contamination levels are given relevance by first correlating them with alpha flux emission levels and then corre1ating these flux values with device soft error rates. Measurement techniques involve either measurements of elemental concentrations-applicable to only uranium and thorium - or direct measurements of alpha emission fluxes. Alpha fluxes are most usefully measured by means of ZnS scintillation counting, practical details of which are discussed. Materials measurements are reported for ceramics, solder, silicon, quartz, and various metals and organic materials. Ceramics and most metals have contamination levels of concern, but the high temperature processing normally used in semiconductor manufacturing and low total amounts reduce problems, at least for metals. Silicon, silicon compounds, and organic materials have been found to have no detectable alpha emitters. Finally, a brief discussion of the calibration of alpha sources for accelerated device testing is given, including practical details on the affects of source/chip separation and alignment variations.

Realization of a Hole-Doped Mott Insulator on a Triangular Silicon Lattice

NASA Astrophysics Data System (ADS)

Ming, Fangfei; Johnston, Steve; Mulugeta, Daniel; Smith, Tyler S.; Vilmercati, Paolo; Lee, Geunseop; Maier, Thomas A.; Snijders, Paul C.; Weitering, Hanno H.

2017-12-01

The physics of doped Mott insulators is at the heart of some of the most exotic physical phenomena in materials research including insulator-metal transitions, colossal magnetoresistance, and high-temperature superconductivity in layered perovskite compounds. Advances in this field would greatly benefit from the availability of new material systems with a similar richness of physical phenomena but with fewer chemical and structural complications in comparison to oxides. Using scanning tunneling microscopy and spectroscopy, we show that such a system can be realized on a silicon platform. The adsorption of one-third monolayer of Sn atoms on a Si(111) surface produces a triangular surface lattice with half filled dangling bond orbitals. Modulation hole doping of these dangling bonds unveils clear hallmarks of Mott physics, such as spectral weight transfer and the formation of quasiparticle states at the Fermi level, well-defined Fermi contour segments, and a sharp singularity in the density of states. These observations are remarkably similar to those made in complex oxide materials, including high-temperature superconductors, but highly extraordinary within the realm of conventional s p -bonded semiconductor materials. It suggests that exotic quantum matter phases can be realized and engineered on silicon-based materials platforms.

Evaluation of transition metal oxide as carrier-selective contacts for silicon heterojunction solar cells

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

Ding, L.; Boccard, Matthieu; Holman, Zachary

2015-04-06

"Reducing light absorption in the non-active solar cell layers, while enabling the extraction of the photogenerated minority carriers at quasi-Fermi levels are two key factors to improve current generation and voltage, and therefore efficiency of silicon heterojunction solar devices. To address these two critical aspects, transition metal oxide materials have been proposed as alternative to the n- and p-type amorphous silicon used as electron and hole selective contacts, respectively. Indeed, transition metal oxides such as molybdenum oxide, titanium oxide, nickel oxide or tungsten oxide combine a wide band gap typically over 3 eV with a band structure and theoretical bandmore » alignment with silicon that results in high transparency to the solar spectrum and in selectivity for the transport of only one carrier type. Improving carrier extraction or injection using transition metal oxide has been a topic of investigation in the field of organic solar cells and organic LEDs; from these pioneering works a lot of knowledge has been gained on materials properties, ways to control these during synthesis and deposition, and their impact on device performance. Recently, the transfer of some of this knowledge to silicon solar cells and the successful application of some metal oxide to contact heterojunction devices have gained much attention. In this contribution, we investigate the suitability of various transition metal oxide films (molybdenum oxide, titanium oxide, and tungsten oxide) deposited either by thermal evaporation or sputtering as transparent hole or electron selective transport layer for silicon solar cells. In addition to systematically characterize their optical and structural properties, we use photoemission spectroscopy to relate compound stoichiometry to band structure and characterize band alignment to silicon. The direct silicon/metal oxide interface is further analyzed by quasi-steady state photoconductance decay method to assess the quality of surface passivation. In complement, we construct full device structures incorporating in some cases surface passivation schemes, with measured initial conversion efficiency over 15% and evaluate the carrier transport properties using temperature-dependent current-voltage and capacitance-voltage measurements. With this detailed characterization study, we aim at providing the framework to assess the potential of a material as a carrier selective contact and the understanding of how each of the aforementioned parameters on the metal oxide films influence the full solar cell operating performances.« less

Magnetic record support

NASA Technical Reports Server (NTRS)

Nakayama, M.; Morita, H.; Tokuoka, Y.; Izumi, T.; Fukuda, K.; Kubota, Y.

1984-01-01

The magnetic layer of a magnetic record support is coated with a thin film of a polymer with a siloxane bond. The magnetic layer consists of a thin film obtained by vacuum metallization, cathode sputtering or dispersion of a ferromagnetic metal powder in a binder. The polymer with a siloxane bond is produced by the polymerization of an organic silicon compound which inherently contains or is able to form this bond. Polymerization is preferably performed by plasma polymerization.

Possible New Irdome Materials for Transmission to 4.5-5 Micrometers.

DTIC Science & Technology

1978-02-01

transmission completel to 5 microns and it has quite a high index or fraction. Several nitrides may be possible candidates with silicon nitride currently...receiving some consideration.1 However, it only transmits to 4.5 microns and also has a fairly high index or fraction. Many mixed nitride compounds are...should meet the IR transmission requirements but these generally have high indices of fraction . Many sulf ides, other chalcogenides, and semi-conductors

Survey of less-inflammable hydraulic fluids for aircraft

NASA Technical Reports Server (NTRS)

Drake, Wray V; Drell, I L

1950-01-01

A survey of current information on civil and military development of less-inflammable hydraulic fluids for aircraft is presented. Types of less-inflammable fluid reported include: glycol derivative, water base, silicone, ester, and halogenated compound. Specification requirements, physical and chemical properties, hydraulic-system test results, and advantages and disadvantages of various hydraulic fluids are discussed. For completely satisfactory service, some modification of currently available fluids or of present hydraulic-system parts still appears necessary.

Aerosol chemical vapor deposition of metal oxide films

DOEpatents

Ott, Kevin C.; Kodas, Toivo T.

1994-01-01

A process of preparing a film of a multicomponent metal oxide including: forming an aerosol from a solution comprised of a suitable solvent and at least two precursor compounds capable of volatilizing at temperatures lower than the decomposition temperature of said precursor compounds; passing said aerosol in combination with a suitable oxygen-containing carrier gas into a heated zone, said heated zone having a temperature sufficient to evaporate the solvent and volatilize said precursor compounds; and passing said volatilized precursor compounds against the surface of a substrate, said substrate having a sufficient temperature to decompose said volatilized precursor compounds whereby metal atoms contained within said volatilized precursor compounds are deposited as a metal oxide film upon the substrate is disclosed. In addition, a coated article comprising a multicomponent metal oxide film conforming to the surface of a substrate selected from the group consisting of silicon, magnesium oxide, yttrium-stabilized zirconium oxide, sapphire, or lanthanum gallate, said multicomponent metal oxide film characterized as having a substantially uniform thickness upon said FIELD OF THE INVENTION The present invention relates to the field of film coating deposition techniques, and more particularly to the deposition of multicomponent metal oxide films by aerosol chemical vapor deposition. This invention is the result of a contract with the Department of Energy (Contract No. W-7405-ENG-36).

Versatile buffer layer architectures based on Ge1-xSnx alloys

NASA Astrophysics Data System (ADS)

Roucka, R.; Tolle, J.; Cook, C.; Chizmeshya, A. V. G.; Kouvetakis, J.; D'Costa, V.; Menendez, J.; Chen, Zhihao D.; Zollner, S.

2005-05-01

We describe methodologies for integration of compound semiconductors with Si via buffer layers and templates based on the GeSn system. These layers exhibit atomically flat surface morphologies, low defect densities, tunable thermal expansion coefficients, and unique ductile properties, which enable them to readily absorb differential stresses produced by mismatched overlayers. They also provide a continuous selection of lattice parameters higher than that of Ge, which allows lattice matching with technologically useful III-V compounds. Using this approach we have demonstrated growth of GaAs, GeSiSn, and pure Ge layers at low temperatures on Si(100). These materials display extremely high-quality structural, morphological, and optical properties opening the possibility of versatile integration schemes directly on silicon.

Extremely bulky secondary phosphinoamines as substituents for sterically hindered aminosilanes.

PubMed

Böttcher, Tobias; Jones, Cameron

2015-09-07

The synthesis of a series of extremely bulky secondary amines with a phosphine function, Ar(†)(PR2)NH (Ar(†) = C6H2{C(H)Ph2}2Pr(i)-2,6,4; R = Ph, NEt2, NPr(i)2) is described. Deprotonation with either n-BuLi or KH yields the respective alkali metal amides in some cases. Their reaction with the chlorosilanes SiCl4, HSiCl3, Cl2SiPh2, Cl3Si-SiCl3 and Si5Cl10 allows access to monomeric molecular compounds bearing the extremely bulky amino substituents via salt elimination. The products obtained may serve as precursors for subsequent reduction reactions to access sterically protected low valent and low coordinate silicon compounds.

(Tl, Sb) and (Tl, Bi) binary surface reconstructions on Ge(111) substrate

NASA Astrophysics Data System (ADS)

Gruznev, D. V.; Bondarenko, L. V.; Tupchaya, A. Y.; Yakovlev, A. A.; Mihalyuk, A. N.; Zotov, A. V.; Saranin, A. A.

2018-03-01

2D compounds made of Group-III and Group-V elements on the surface of silicon and germanium attract considerable attention due to prospects of creating III-V binary monolayers, which are predicted to hold advanced physical properties. In the present work, we have investigated two such systems, (Tl, Sb)/Ge(111) and (Tl, Bi)/Ge(111) using scanning tunneling microscopy, low energy electron diffraction observations and density-functional-theory calculations. In addition to the previously reported surface structures of 2D (Tl, Sb) and (Tl, Bi) compounds on Si(111), we found new ones, namely, √{ 7} × √{ 7} and 3 × 3. Formation processes and plausible models of their atomic arrangements are discussed.

Computational assessment of organic photovoltaic candidate compounds

NASA Astrophysics Data System (ADS)

Borunda, Mario; Dai, Shuo; Olivares-Amaya, Roberto; Amador-Bedolla, Carlos; Aspuru-Guzik, Alan

2015-03-01

Organic photovoltaic (OPV) cells are emerging as a possible renewable alternative to petroleum based resources and are needed to meet our growing demand for energy. Although not as efficient as silicon based cells, OPV cells have as an advantage that their manufacturing cost is potentially lower. The Harvard Clean Energy Project, using a cheminformatic approach of pattern recognition and machine learning strategies, has ranked a molecular library of more than 2.6 million candidate compounds based on their performance as possible OPV materials. Here, we present a ranking of the top 1000 molecules for use as photovoltaic materials based on their optical absorption properties obtained via time-dependent density functional theory. This computational search has revealed the molecular motifs shared by the set of most promising molecules.

Method for estimating protein binding capacity of polymeric systems.

PubMed

Sharma, Vaibhav; Blackwood, Keith A; Haddow, David; Hook, Lilian; Mason, Chris; Dye, Julian F; García-Gareta, Elena

2015-01-01

Composite biomaterials made from synthetic and protein-based polymers are extensively researched in tissue engineering. To successfully fabricate a protein-polymer composite, it is critical to understand how strongly the protein binds to the synthetic polymer, which occurs through protein adsorption. Currently, there is no cost-effective and simple method for characterizing this interfacial binding. To characterize this interfacial binding, we introduce a simple three-step method that involves: 1) synthetic polymer surface characterisation, 2) a quick, inexpensive and robust novel immuno-based assay that uses protein extraction compounds to characterize protein binding strength followed by 3) an in vitro 2D model of cell culture to confirm the results of the immuno-based assay. Fibrinogen, precursor of fibrin, was adsorbed (test protein) on three different polymeric surfaces: silicone, poly(acrylic acid)-coated silicone and poly(allylamine)-coated silicone. Polystyrene surface was used as a reference. Characterisation of the different surfaces revealed different chemistry and roughness. The novel immuno-based assay showed significantly stronger binding of fibrinogen to both poly(acrylic acid) and poly(allylamine) coated silicone. Finally, cell studies showed that the strength of the interaction between the protein and the polymer had an effect on cell growth. This novel immuno-based assay is a valuable tool in developing composite biomaterials of synthetic and protein-based polymers with the potential to be applied in other fields of research where protein adsorption onto surfaces plays an important role.

Optical Absorption and Visible Photoluminescence from Thin Films of Silicon Phthalocyanine Derivatives

PubMed Central

Rodríguez Gómez, Arturo; Moises Sánchez-Hernández, Carlos; Fleitman-Levin, Ilán; Arenas-Alatorre, Jesús; Carlos Alonso-Huitrón, Juan; Elena Sánchez Vergara, María

2014-01-01

The interest of microelectronics industry in new organic compounds for the manufacture of luminescent devices has increased substantially in the last decade. In this paper, we carried out a study of the usage feasibility of three organic bidentate ligands (2,6-dihydroxyanthraquinone, anthraflavic acid and potassium derivative salt of anthraflavic acid) for the synthesis of an organic semiconductor based in silicon phthalocyanines (SiPcs). We report the visible photoluminescence (PL) at room temperature obtained from thermal-evaporated thin films of these new materials. The surface morphology of these films was analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). AFM indicated that the thermal evaporation technique is an excellent resource in order to obtain low thin film roughness when depositing these kinds of compounds. Fourier transform infrared spectroscopy (FTIR) spectroscopy was employed to investigate possible changes in the intra-molecular bonds and to identify any evidence of crystallinity in the powder compounds and in the thin films after their deposition. FTIR showed that there was not any important change in the samples after the thermal deposition. The absorption coefficient (α) in the absorption region reveals non-direct transitions. Furthermore, the PL of all the investigated samples were observed with the naked eye in a bright background and also measured by a spectrofluorometer. The normalized PL spectra showed a Stokes shift ≈ 0.6 eV in two of our three samples, and no PL emission in the last one. Those results indicate that the Vis PL comes from a recombination of charge carriers between conduction band and valence band preceded by a non-radiative relaxation in the conduction band tails. PMID:28788200

Terahertz artificial birefringence and tunable phase shifter based on dielectric metasurface with compound lattice.

PubMed

Ji, Yun-Yun; Fan, Fei; Chen, Meng; Yang, Lei; Chang, Sheng-Jiang

2017-05-15

A dielectric metasurface with line-square compound lattice structure has been fabricated and demonstrated in the terahertz (THz) regime by the THz time-domain spectroscopy and numerical simulation. A polarization dependent electromagnetically induced transparency (EIT) effect is achieved in this metasurface due to the mode coupling and interference between the resonance modes in line and square subunits of the metasurface. Accompany with the EIT effect, a large artificial birefringence effect between two orthogonal polarization states is also observed in this compound metasurface, of which birefringence is over 0.6. Furthermore, the liquid crystals are filled on the surface of this dielectric metasurface to fabricate an electrically tunable THz LC phase shifter. The experimental results show that its tunable phase shift under the biased electric field reaches 0.33π, 1.8 times higher than the bare silicon, which confirms the enhancement role of THz microstructure on the LC phase shift in the THz regime. The large birefringence phase shift of this compound metasurface and its LC tunable phase shifter will be of great significance for potential applications in THz polarization and phase devices.

Optical detection of two-color-fluorophore barcode for nanopore DNA sensing

NASA Astrophysics Data System (ADS)

Zhang, M.; Sychugov, I.; Schmidt, T.; Linnros, J.

2015-06-01

A simple schematic on parallel optical detection of two-fluorophore barcode for single-molecule nanopore sensing is presented. The chosen two fluorophores, ATTO-532 and DY-521-XL, emitting in well-separated spectrum range can be excited at the same wavelength. A beam splitter was employed to separate signals from the two fluorophores and guide them to the same CCD camera. Based on a conventional microscope, sources of background in the nanopore sensing system, including membranes, compounds in buffer solution, and a detection cell was characterized. By photoluminescence excitation measurements, it turned out that silicon membrane has a negligible photoluminescence under the examined excitation from 440 nm to 560 nm, in comparison with a silicon nitrite membrane. Further, background signals from the detection cell were suppressed. Brownian motion of 450 bps DNA labelled with single ATTO-532 or DY-521-XL was successfully recorded by our optical system.

High voltage insulation of bushing for HTS power equipment

NASA Astrophysics Data System (ADS)

Kim, Woo-Jin; Choi, Jae-Hyeong; Kim, Sang-Hyun

2012-12-01

For the operation of high temperature superconducting (HTS) power equipments, it is necessary to develop insulating materials and high voltage (HV) insulation technology at cryogenic temperature of bushing. Liquid nitrogen (LN2) is an attractive dielectric liquid. Also, the polymer insulating materials are expected to be used as solid materials such as glass fiber reinforced plastic (GFRP), polytetra-fluoroethylene (PTFE, Teflon), Silicon (Si) rubber, aromatic polyamide (Nomex), EPDM/Silicon alloy compound (EPDM/Si). In this paper, the surface flashover characteristics of various insulating materials in LN2 are studied. These results are studied at both AC and impulse voltage under a non-uniform field. The use of GFRP and Teflon as insulation body for HTS bushing should be much desirable. Especially, GFRP is excellent material not only surface flashover characteristics but also mechanical characteristics at cryogenic temperature. The surface flashover is most serious problem for the shed design in LN2 and operation of superconducting equipments.

Methods and apparatus for mid-infrared sensing

DOEpatents

Lin, Pao Tai; Cai, Yan; Agarwal, Anuradha Murthy; Kimerling, Lionel C.

2015-06-02

A chip-scale, air-clad semiconductor pedestal waveguide can be used as a mid-infrared (mid-IR) sensor capable of in situ monitoring of organic solvents and other analytes. The sensor uses evanescent coupling from a silicon or germanium waveguide, which is highly transparent in the mid-IR portion of the electromagnetic spectrum, to probe the absorption spectrum of fluid surrounding the waveguide. Launching a mid-IR beam into the waveguide exposed to a particular analyte causes attenuation of the evanescent wave's spectral components due to absorption by carbon, oxygen, hydrogen, and/or nitrogen bonds in the surrounding fluid. Detecting these changes at the waveguide's output provides an indication of the type and concentration of one or more compounds in the surrounding fluid. If desired, the sensor may be integrated onto a silicon substrate with a mid-IR light source and a mid-IR detector to form a chip-based spectrometer.

Multilayer Article Characterized by Low Coefficient of Thermal Expansion Outer Layer

NASA Technical Reports Server (NTRS)

Lee, Kang N. (Inventor)

2004-01-01

A multilayer article comprises a substrate comprising a ceramic or a silicon-containing metal alloy. The ceramic is a Si-containing ceramic or an oxide ceramic with or without silicon. An outer layer overlies the substrate and at least one intermediate layer is located between the outer layer and thc substrate. An optional bond layer is disposed between thc 1 least one intermediate layer and thc substrate. The at least one intermediate layer may comprise an optional chemical barrier layer adjacent the outer layer, a mullite-containing layer and an optional chemical barrier layer adjacent to the bond layer or substrate. The outer layer comprises a compound having a low coefficient of thermal expansion selected from one of the following systems: rare earth (RE) silicates; at least one of hafnia and hafnia-containing composite oxides; zirconia-containing composite oxides and combinations thereof.

Aminopropyl-modified magnesium-phyllosilicates: layered solids with tailored interlayer access and reactivity.

PubMed

Ferreira, Ricardo B; da Silva, César R; Pastore, Heloise O

2008-12-16

Despite its wide application, the synthesis of aminopropyl-modified magnesium-phyllosilicates was known only in the case where every silicon atom bore an organic pending group. This paper shows the preparation of aminopropyl-modified talc where tailored amounts of silicon atoms are bound to an aminopropyl group. The decrease in the concentration of the organoamino group leaves a proportional concentration of interlayer SiOH groups that can be used to react with other silylation agents. The amino group reacts with CO2, forming a carbamate functionality; it seems that the presence of this group avoids delamination in water as performed for the parent compound. Bearing in mind that the aminopropyl group can be changed by other groups, the present synthesis strategy demonstrates ways to produce solids with controlled surface properties with interlayer amino and SiOH groups in variable concentrations, allowing formation of several other interlayer functionalities.

Carbothermic reduction of uranium oxides into solvent metallic baths

NASA Astrophysics Data System (ADS)

Guisard Restivo, Thomaz A.; Capocchi, José D. T.

2004-09-01

The carbothermic reduction of UO 2 and U 3O 8 is studied employing tin and silicon solvent metallic baths in thermal analysis equipment, under Ar inert and N 2 reactive atmospheres. The metallic solvents are expected to lower the U activity by several orders of magnitude owing to strong interactions among the metals. The reduction products are composed of the solvent metal matrix and intermetallic U compounds. Silicon is more effective in driving the reduction since there is no residual UO 2 after the reaction. The gaseous product detected by mass spectrometer (MS) during the reduction is CO. A kinetic study for the Si case was accomplished by the stepwise isothermal analysis (SAI) method, leading to the identification of the controlling mechanisms as chemical reaction at the surface and nucleation, for UO 2 and U 3O 8 charges, respectively. One example for another system containing Al 2O 3 is also shown.

Novel duplex vapor-electrochemical method for silicon solar cells. [reaction of fluorine and silicon compounds with sodium

NASA Technical Reports Server (NTRS)

Nanis, L.; Sanjurjo, A.; Sancier, K. M.; Bartlett, R.; Westphal, S.

1979-01-01

The dependence of the SiF4 Na reaction initiation time and of the efficiency of the reaction on Na particle size and reaction temperature were studied. Close to 100 percent utilization of Na was obtained, and formation of byproduct fluoro-silicate was decreased to below 10 percent. A SiF4 Na reactor was built to scale up the reaction by a factor of about four and is now being tested. A scaled up melting system was built and successfully used to separate Si from kilogram quantities of SiF4 NaF mixtures. Support studies of the volatilization of NaF performed in a smaller melting system indicated minimal loss of NaF as vapor at 1410 C. The wetting of graphite was also investigated to determine the constituents of the NaF phase which promote good wetting.

Ab initio structure prediction of silicon and germanium sulfides for lithium-ion battery materials

NASA Astrophysics Data System (ADS)

Hsueh, Connie; Mayo, Martin; Morris, Andrew J.

Conventional experimental-based approaches to materials discovery, which can rely heavily on trial and error, are time-intensive and costly. We discuss approaches to coupling experimental and computational techniques in order to systematize, automate, and accelerate the process of materials discovery, which is of particular relevance to developing new battery materials. We use the ab initio random structure searching (AIRSS) method to conduct a systematic investigation of Si-S and Ge-S binary compounds in order to search for novel materials for lithium-ion battery (LIB) anodes. AIRSS is a high-throughput, density functional theory-based approach to structure prediction which has been successful at predicting the structures of LIBs containing sulfur and silicon and germanium. We propose a lithiation mechanism for Li-GeS2 anodes as well as report new, theoretically stable, layered and porous structures in the Si-S and Ge-S systems that pique experimental interest.

Novel Gas Sensor Arrays Based on High-Q SAM-Modified Piezotransduced Single-Crystal Silicon Bulk Acoustic Resonators

PubMed Central

Zhao, Yuan; Yang, Qingrui; Chang, Ye; Pang, Wei; Zhang, Hao; Duan, Xuexin

2017-01-01

This paper demonstrates a novel micro-size (120 μm × 200 μm) piezoelectric gas sensor based on a piezotransduced single-crystal silicon bulk acoustic resonator (PSBAR). The PSBARs operate at 102 MHz and possess high Q values (about 2000), ensuring the stability of the measurement. A corresponding gas sensor array is fabricated by integrating three different self-assembled monolayers (SAMs) modified PSBARs. The limit of detection (LOD) for ethanol vapor is demonstrated to be as low as 25 ppm with a sensitivity of about 1.5 Hz/ppm. Two sets of identification code bars based on the sensitivities and the adsorption energy constants are utilized to successfully discriminate isopropanol (IPA), ethanol, hexane and heptane vapors at low and high gas partial pressures, respectively. The proposed sensor array shows the potential to form a portable electronic nose system for volatile organic compound (VOC) differentiation. PMID:28672852

Novel Gas Sensor Arrays Based on High-Q SAM-Modified Piezotransduced Single-Crystal Silicon Bulk Acoustic Resonators.

PubMed

Zhao, Yuan; Yang, Qingrui; Chang, Ye; Pang, Wei; Zhang, Hao; Duan, Xuexin

2017-06-26

This paper demonstrates a novel micro-size (120 μm × 200 μm) piezoelectric gas sensor based on a piezotransduced single-crystal silicon bulk acoustic resonator (PSBAR). The PSBARs operate at 102 MHz and possess high Q values (about 2000), ensuring the stability of the measurement. A corresponding gas sensor array is fabricated by integrating three different self-assembled monolayers (SAMs) modified PSBARs. The limit of detection (LOD) for ethanol vapor is demonstrated to be as low as 25 ppm with a sensitivity of about 1.5 Hz/ppm. Two sets of identification code bars based on the sensitivities and the adsorption energy constants are utilized to successfully discriminate isopropanol (IPA), ethanol, hexane and heptane vapors at low and high gas partial pressures, respectively. The proposed sensor array shows the potential to form a portable electronic nose system for volatile organic compound (VOC) differentiation.

In vitro action of progestogens on sperm migration in human cervical mucus;.

PubMed

Kesserü, E; Camacho-Ortega, P; Laudahn, G; Schopflin, G

1975-01-01

The presence of progestogens in the cervical mucus suppresses and arrests sperm penetration. Using the Kremer technique, the effects of in vitro released progesterone, d-norgestrel, and cyproterone acetate were studied by inserting silicone rubber threads bearing the respective compounds into capillary tubes containing cervical mucus. Control tubes were fitted with nonmedicated silicone rubber threads. After 24 hours of incubation, the sperm migration test was carried out to evaluate penetration depth, qualitative motility, and proportion of motile forms. Progesterone produced the greatest alterations. Migration was arrested within 30 minutes, the distance reached was consistently less than 2 cm, and sperm were completely immobile at 24 hours. D-norgestrel also exhibited a distinct spermiostatic effect, but it was not as intense as that of progesterone. Cyproterone acetate was practically effective during the first 120 minutes and produced alterations only in the qualitative and proportional motility.

Integrated resonant micro-optical gyroscope and method of fabrication

DOEpatents

Vawter, G Allen [Albuquerque, NM; Zubrzycki, Walter J [Sandia Park, NM; Guo, Junpeng [Albuquerque, NM; Sullivan, Charles T [Albuquerque, NM

2006-09-12

An integrated optic gyroscope is disclosed which is based on a photonic integrated circuit (PIC) having a bidirectional laser source, a pair of optical waveguide phase modulators and a pair of waveguide photodetectors. The PIC can be connected to a passive ring resonator formed either as a coil of optical fiber or as a coiled optical waveguide. The lasing output from each end of the bidirectional laser source is phase modulated and directed around the passive ring resonator in two counterpropagating directions, with a portion of the lasing output then being detected to determine a rotation rate for the integrated optical gyroscope. The coiled optical waveguide can be formed on a silicon, glass or quartz substrate with a silicon nitride core and a silica cladding, while the PIC includes a plurality of III V compound semiconductor layers including one or more quantum well layers which are disordered in the phase modulators and to form passive optical waveguides.

Equation of state for shock compression of distended solids

NASA Astrophysics Data System (ADS)

Grady, Dennis; Fenton, Gregg; Vogler, Tracy

2014-05-01

Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additive measures of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence reveals enhancement of shock-induced phase transformation on the Hugoniot with increasing levels of initial distension for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed feature of the shock compression are incorporated into the EOS model.

Equation of State for Shock Compression of High Distension Solids

NASA Astrophysics Data System (ADS)

Grady, Dennis

2013-06-01

Shock Hugoniot data for full-density and porous compounds of boron carbide, silicon dioxide, tantalum pentoxide, uranium dioxide and playa alluvium are investigated for the purpose of equation-of-state representation of intense shock compression. Complications of multivalued Hugoniot behavior characteristic of highly distended solids are addressed through the application of enthalpy-based equations of state of the form originally proposed by Rice and Walsh in the late 1950's. Additivity of cold and thermal pressure intrinsic to the Mie-Gruneisen EOS framework is replaced by isobaric additive functions of the cold and thermal specific volume components in the enthalpy-based formulation. Additionally, experimental evidence supports acceleration of shock-induced phase transformation on the Hugoniot with increasing levels of initial distention for silicon dioxide, uranium dioxide and possibly boron carbide. Methods for addressing this experimentally observed facet of the shock compression are introduced into the EOS model.

Silicon: Child and Progenitor of Revolution

NASA Astrophysics Data System (ADS)

Cahn, R. W.

Antoine Lavoisier, the pioneering French chemist who (together with Joseph Priestley in England) identified oxygen as an element and gave it its name, in 1789 concluded that quartz was probably a compound with an as-yet undiscovered but presumably extremely common element. That was also the year in which the French Revolution broke out. Five years later, the Jacobins accused Lavoisier of offences against the people and cut off his head, thereby nearly cutting off the new chemistry. It was not until 1824 that Jöns Berzelius in Sweden succeeded in confirming Lavoisier's speculation by isolating silicon. Argument at once broke out among the scientific elite as to whether the newly found element was a metal or an insulator. It took more than a century to settle that disagreement decisively: As so often, when all-or-nothing alternatives are fiercely argued, the truth turned out to be neither all nor nothing.

Process for producing an aggregate suitable for inclusion into a radiation shielding product

DOEpatents

Lessing, Paul A.; Kong, Peter C.

2000-01-01

The present invention is directed to methods for converting depleted uranium hexafluoride to a stable depleted uranium silicide in a one-step reaction. Uranium silicide provides a stable aggregate material that can be added to concrete to increase the density of the concrete and, consequently, shield gamma radiation. As used herein, the term "uranium silicide" is defined as a compound generically having the formula U.sub.x Si.sub.y, wherein the x represents the molecules of uranium and the y represent the molecules of silicon. In accordance with the present invention, uranium hexafluoride is converted to a uranium silicide by contacting the uranium hexafluoride with a silicon-containing material at a temperature in a range between about 1450.degree. C. and about 1750.degree. C. The stable depleted uranium silicide is included as an aggregate in a radiation shielding product, such as a concrete product.

Effects of inorganic substances on water splitting in ion-exchange membranes; II. Optimal contents of inorganic substances in preparing bipolar membranes.

PubMed

Kang, Moon-Sung; Choi, Yong-Jin; Moon, Seung-Hyeon

2004-05-15

An approach to enhancing the water-splitting performance of bipolar membranes (BPMs) is introducing an inorganic substance at the bipolar (BP) junction. In this study, the immobilization of inorganic matters (i.e., iron hydroxides and silicon compounds) at the BP junction and the optimum concentration have been investigated. To immobilize these inorganic matters, novel methods (i.e., electrodeposition of the iron hydroxide and processing of the sol-gel to introduce silicon groups at the BP junction) were suggested. At optimal concentrations, the immobilized inorganic matters significantly enhanced the water-splitting fluxes, indicating that they provide alternative paths for water dissociation, but on the other hand possibly reduce the polarization of water molecules between the sulfonic acid and quaternary ammonium groups at high contents. Consequently, the amount of inorganic substances introduced should be optimized to obtain the maximum water splitting in the BPM.

Defense Small Business Innovation Research Program (SBIR). Abstracts of Phase II Awards. 1985.

DTIC Science & Technology

1985-01-01

SILICIDES : NEW SILICON COMPATIBLE ELECTRO-OPTIC MATERIALS TOPIC: 3 OFFICE: DARPA THE GOAL OF THIS WORK IS TO OBTAIN SINGLE CRYSTAL FILMS OF SEMI...CONSTITUENTS. CON- STITUENTS WITH IONIZATION POTENTIALS COMPARABLE TO THE WORK FUNCTION A ARE EVOLVED AS POSITIVE IONS (USUALLY SODIUM ATOMIC IONS FROM... SODIUM COMPOUND IMPURITIES). ARRIVAL OF A PARTICLE AT THE SURFACE CAUSES A BURST OF MANY IONS WHICH ARE DRAWN TO A NEARBY ION COLLECTOR ELECT- RODE

Manufacturing Science of Improved Molded Optics

DTIC Science & Technology

2013-12-05

Forrer, “Interaction of N-FK5 and L- BAL35 optical glass with various carbide and other precision glass mold tooling”, SPIE Optifab 2013 Conference...Richardson, S. Mourad, M. Huber, A. Kunz, M. Forrer. Interaction of N-FK5 and L-BAL35 optical glass with various carbide and other precision glass mold...stoichiometric compounds. As an example, if silicon and oxygen are present in a material, then it was assumed that they are present in the form of

Friction welded nonconsumable electrode assembly and use thereof for electrolytic production of metals and silicon

DOEpatents

Byrne, Stephen C.; Ray, Siba P.; Rapp, Robert A.

1984-01-01

A nonconsumable electrode assembly suitable for use in the production of metal by electrolytic reduction of a metal compound dissolved in a molten salt, the assembly comprising a metal conductor and a ceramic electrode body connected by a friction weld between a portion of the body having a level of free metal or metal alloy sufficient to effect such a friction weld and a portion of the metal conductor.

GaN High Power Electronics

DTIC Science & Technology

2011-02-01

ARL) does not yet match the best work being done in Japan, the reasons for this have been identified as the relatively large carbon background...hand, SiC is a compound with a fixed composition. Second phases are formed, as opposed to solid solutions, when the group IV elements, carbon (C...Si, or germanium (Ge), are added to it. In order to form a 2DEG, a dielectric, usually silicon dioxide (SiO2), has to be grown or deposited on the

Cross Validation of Two Partitioning-Based Sampling Approaches in Mesocosms Containing PCB Contaminated Field Sediment, Biota, and Activated Carbon Amendment.

PubMed

Schmidt, Stine N; Wang, Alice P; Gidley, Philip T; Wooley, Allyson H; Lotufo, Guilherme R; Burgess, Robert M; Ghosh, Upal; Fernandez, Loretta A; Mayer, Philipp

2017-09-05

The Gold Standard for determining freely dissolved concentrations (C free ) of hydrophobic organic compounds in sediment interstitial water would be in situ deployment combined with equilibrium sampling, which is generally difficult to achieve. In the present study, ex situ equilibrium sampling with multiple thicknesses of silicone and in situ pre-equilibrium sampling with low density polyethylene (LDPE) loaded with performance reference compounds were applied independently to measure polychlorinated biphenyls (PCBs) in mesocosms with (1) New Bedford Harbor sediment (MA, U.S.A.), (2) sediment and biota, and (3) activated carbon amended sediment and biota. The aim was to cross validate the two different sampling approaches. Around 100 PCB congeners were quantified in the two sampling polymers, and the results confirmed the good precision of both methods and were in overall good agreement with recently published LDPE to silicone partition ratios. Further, the methods yielded C free in good agreement for all three experiments. The average ratio between C free determined by the two methods was factor 1.4 ± 0.3 (range: 0.6-2.0), and the results thus cross-validated the two sampling approaches. For future investigations, specific aims and requirements in terms of application, data treatment, and data quality requirements should dictate the selection of the most appropriate partitioning-based sampling approach.

First-Principles Calculations of Electronic, Optical, and Transport Properties of Materials for Energy Applications

NASA Astrophysics Data System (ADS)

Shi, Guangsha

Solar electricity is a reliable and environmentally friendly method of sustainable energy production and a realistic alternative to conventional fossil fuels. Moreover, thermoelectric energy conversion is a promising technology for solid-state refrigeration and efficient waste-heat recovery. Predicting and optimizing new photovoltaic and thermoelectric materials composed of Earth-abundant elements that exceed the current state of the art, and understanding how nanoscale structuring and ordering improves their energy conversion efficiency pose a challenge for materials scientists. I approach this challenge by developing and applying predictive high-performance computing methods to guide research and development of new materials for energy-conversion applications. Advances in computer-simulation algorithms and high-performance computing resources promise to speed up the development of new compounds with desirable properties and significantly shorten the time delay between the discovery of new materials and their commercial deployment. I present my calculated results on the extraordinary properties of nanostructured semiconductor materials, including strong visible-light absorbance in nanoporous silicon and few-layer SnSe and GeSe. These findings highlight the capability of nanoscale structuring and ordering to improve the performance of Earth-abundant materials compared to their bulk counterparts for solar-cell applications. I also successfully identified the dominant mechanisms contributing to free-carrier absorption in n-type silicon. My findings help evaluate the impact of the energy loss from this absorption mechanism in doped silicon and are thus important for the design of silicon solar cells. In addition, I calculated the thermoelectric transport properties of p-type SnSe, a bulk material with a record thermoelectric figure of merit. I predicted the optimal temperatures and free-carrier concentrations for thermoelectric energy conversion, as well the theoretical upper limit of the figure of merit. I also determined the electronic structures and thermoelectric properties of Mg2Si, Mg2Ge, and Mg2Sn, a family of Earth-abundant thermoelectric compounds. I uncovered the importance of quasiparticle corrections and the proper treatment of pseudopotentials in the determination of the band gaps and the thermoelectric transport properties at high temperatures. The methods and codes I developed in my research form a general predictive toolbox for the design and optimization of the functional properties of materials for energy applications.

Encapsulation and controlled release of retinol from silicone particles for topical delivery.

PubMed

Shields, C Wyatt; White, John P; Osta, Erica G; Patel, Jerishma; Rajkumar, Shashank; Kirby, Nickolas; Therrien, Jean-Philippe; Zauscher, Stefan

2018-05-28

Retinol, a derivative of vitamin A, is a ubiquitous compound used to treat acne, reduce wrinkles and protect against conditions like psoriasis and ichthyosis. While retinol is used as the primary active ingredient (AI) in many skin care formulations, its efficacy is often limited by an extreme sensitivity to degrade and toxicity at high concentrations. While microencapsulation is an appealing method to help overcome these issues, few microencapsulation strategies have made a major translational impact due to challenges with complexity, cost, limited protection of the AI and poor control of the release of the AI. We have developed a class of silicone particles that addresses these challenges for the encapsulation, protection and controlled release of retinol and other hydrophobic compounds. The particles are prepared by the sol-gel polymerization of silane monomers, which enables their rapid and facile synthesis at scale while maintaining a narrow size distribution (i.e., CV < 20%). We show that our particles can: (i) encapsulate retinol with high efficiency (>85%), (ii) protect retinol from degradation (yielding a half-life 9× greater than unencapsulated retinol) and (iii) slowly release retinol over several hours (at rates from 0.14 to 0.67 μg cm -2  s -1/2 ). To demonstrate that the controlled release of retinol from the particles can reduce irritation, we performed a double blind study on human subjects and found that formulations containing our particles were 12-23% less irritating than identical formulations containing Microsponge® particles (an industry standard by Amcol, Inc.). To show that the silicone particles can elicit a favorable biological response, similar to the Microsponge® particles, we applied both formulations to reconstructed human epidermal tissues and found an upregulation of keratin 19 (K19) and a downregulation of K10, indicating that the reduced irritation observed in the human study was not caused by reduced activity. We also found a decrease in the production of interleukin-1α (IL-1α) compared to formulations containing the Microsponge particles, suggesting lower irritation levels and supporting the findings from the human study. Finally, we show that the silicone particles can encapsulate other AIs, including betamethasone, N, N-diethyl-meta-toluamide (DEET), homosalate and ingenol mebutate, establishing these particles as a true platform technology. Copyright © 2018. Published by Elsevier B.V.

Recent Trends in Biosensors

NASA Astrophysics Data System (ADS)

Karube, Isao

The determination of organic compounds in foods is very important in food industries. A various compounds are contained in foods, selective determination methods are required for food processing and analysis. Electrochemical monitoring devices (biosensors) employing immobilized biocatalysts such as immobilized enzymes, organelles, microorganisms, and tissue have definite advantages. The enzyme Sensors consisted of immobilized enzymes and electrochemical devices. Enzyme sensors could be used for the determination of sugars, amino acids, organic acids, alcohols, lipids, nucleic acid derivatives, etc.. Furthermore, a multifunctional biosensor for the determination of several compounds has been developed for food processing. On the other hand, microbial sensors consisted of immobilized microorganisms and electrodes have been used for industrial and environmental analysis. Microbial sensors were applied for the determination of sugars, organic acids, alcohols, amino acids, mutagens, me thane, ammonia, and BOD. Furthermore, micro-biosensors using immobilized biocatalysts and ion sensitive field effect transistor or microelectrodes prepared by silicon fabrication technologies have been developed for medical ap. plication and food processing. This review summarizes the design and application of biosensors.

In vitro simulation studies of silica deposition induced by lignin from rice*

PubMed Central

Fang, Jiang-Yu; Ma, Xue-Long

2006-01-01

To reveal the possible mechanism of silica deposition in higher plants, lignin was isolated from rice straw following a modified method to conduct a simulation experiment in vitro. UV and infrared absorption spectra showed that the substance had the unique characteristics of pure lignin. The presence of silicon in the precipitation was revealed by TEM (transmission electron microscopy) with EDXA (energy dispersive X-ray analysis) device. It was found that in the borax solution where lignin precipitation occurred silica-lignin co-precipitation was produced but not in the DMSO solution where lignin was broken into its composition compounds and did not precipitate. This means that it is macromolecular lignin itself but not its compounds that could induce silica deposition in higher plants. PMID:16532527

Combustion system processes leading to corrosive deposits

NASA Technical Reports Server (NTRS)

Stearns, C. A.; Kohl, F. J.; Rosner, D. E.

1981-01-01

Degradation of turbine engine hot gas path components by high temperature corrosion can usually be associated with deposits even though other factors may also play a significant role. The origins of the corrosive deposits are traceable to chemical reactions which take place during the combustion process. In the case of hot corrosion/sulfidation, sodium sulfate was established as the deposited corrosive agent even when none of this salt enters the engine directly. The sodium sulfate is formed during the combustion and deposition processes from compounds of sulfur contained in the fuel as low level impurities and sodium compounds, such as sodium chloride, ingested with intake air. In other turbine and power generation situations, corrosive and/or fouling deposits can result from such metals as potassium, iron, calcium, vanadium, magnesium, and silicon.

Uncharged positive electrode composition

DOEpatents

Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

1977-03-08

An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

Vacuum and ultraviolet radiation effects on binders and pigments for spacecraft thermal control coatings

NASA Technical Reports Server (NTRS)

Progar, D. J.; Wade, W. R.

1971-01-01

An evaluation of several silicone resin binders and powdered inorganic pigments for potential use in spacecraft thermal-control paint formulations is presented. The pigments were selected on the basis of a hypothesis relating the heat of formation of a compound to the compound's resistance to ultra-radiation-induced degradation. Reflectance measurements were made in situ to determine degradation rates due to ultraviolet radiation. The tested polydimethylsiloxane resins were not significantly affected by long exposures to ultraviolet radiation. All the pigments, which were dispersed in a polydimethylsiloxane resin, were degraded by ultraviolet radiation as determined by an increase of solar absorptance. For the materials evaluated in this study, no evidence was found to indicate that pigments with high heats of formation were resistant to ultraviolet degradation.

Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

PubMed Central

Kolel-Veetil, Manoj K.; Keller, Teddy M.

2010-01-01

The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe3Si, Fe5Si3, FeSi, α-FeSi2 and β-FeSi2. While the iron-rich silicides Fe3Si and Fe5Si3 are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe5Si3 has also been demonstrated to exhibit giant magnetoresistance (GMR). The silicon-rich β-FeSi2 is a direct band gap material usable in light emitting diode (LED) applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM) of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe)-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.

Structural diversity and electronic properties in potassium silicides

NASA Astrophysics Data System (ADS)

Hao, Chun-Mei; Li, Yunguo; Huang, Hong-Mei; Li, Yan-Ling

2018-05-01

Stable potassium silicides in the complete compositional landscape were systematically explored up to 30 GPa using the variable-composition evolutionary structure prediction method. The results show that K4Si, K3Si, K5Si2, K2Si, K3Si2, KSi, KSi2, KSi3, and K8Si46 have their stability fields in the phase diagram. The spatial dimensional diversity of polymerized silicon atoms (0D "isolated" anion, dimer, Si4 group, 1D zigzag chain, 2D layer, and 3D network) under the potassium sublattice was uncovered as silicon content increases. Especially, the 2D layered silicon presents interestingly a variety of shapes, such as the "4 + 6" ring, "4 + 8"ring, and 8-membered ring. K-Si bonding exhibits a mixed covalency and ionicity, while Si-Si bonding is always of covalent character. Semiconductivity or metallicity mainly depends on the form of sublattices and K:Si ratio, which allows us to find more semiconductors in the Si-rich side when closed-shell K cations are encompassed by polymerized Si. The semiconducting silicides present strong absorption in the infrared and visible light range. These findings open up the avenue for experimental synthesis of alkali metal-IVA compounds and potential applications as battery electrode materials or photoelectric materials.

Temperature Dependence of Diffusion and Reaction at a Pd/SiC Contact

NASA Technical Reports Server (NTRS)

Shi, D.T.; Lu, W. J.; Bryant, E.; Elshot, K.; Lafate, K.; Chen, H.; Burger, A.; Collins, W. E.

1998-01-01

Schottky diodes of Palladium/SiC are good candidates for hydrogen and hydrocarbon gas sensors at elevated temperature. The detection sensibility of the diodes has been found heavily temperature dependent. In this work, emphasis has been put on the understanding of changes of physical and chemical properties of the Schottky diodes with variation of temperature. Schottky diodes were made by depositing ultra-thin palladium films onto silicon carbide substrates. The electrical and chemical properties of Pd/SiC Schottky contacts were studied by XPS and AES at different annealing temperatures. No significant change in the Schottky barrier height of the Pd/SiC contact was found in the temperature range of RT-400 C. However, both palladium diffused into SiC and silicon migrated into palladium thin film as well as onto surface were observed at room temperature. The formation of palladium compounds at the Pd/SiC interface was also observed. Both diffusion and reaction at the Pd/SiC interface became significant at 300 C and higher temperature. In addition, silicon oxide was found also at the interface of the Pd/SiC contact at high temperature. In this report, the mechanism of diffusion and reaction at the Pd/SiC interface will be discussed along with experimental approaches.

A polymer-based Fabry-Perot filter integrated with 3-D MEMS structures

NASA Astrophysics Data System (ADS)

Zhang, Ping (Cerina); Le, Kevin; Malalur-Nagaraja-Rao, Smitha; Hsu, Lun-Chen; Chiao, J.-C.

2006-01-01

Polymers have been considered as one of the most versatile materials in making optical devices for communication and sensor applications. They provide good optical transparency to form filters, lenses and many optical components with ease of fabrication. They are scalable and compatible in dimensions with requirements in optics and can be fabricated on inorganic substrates, such as silicon and quartz. Recent polymer synthesis also made great progresses on conductive and nonlinear polymers, opening opportunities for new applications. In this paper, we discussed hybrid-material integration of polymers on silicon-based microelectromechanical system (MEMS) devices. The motivation is to combine the advantages of demonstrated silicon-based MEMS actuators and excellent optical performance of polymers. We demonstrated the idea with a polymer-based out-of-plane Fabry-Perot filter that can be self-assembled by scratch drive actuators. We utilized a fabrication foundry service, MUMPS (Multi-User MEMS Process), to demonstrate the feasibility and flexibility of integration. The polysilicon, used as the structural material for construction of 3-D framework and actuators, has high absorption in the visible and near infrared ranges. Therefore, previous efforts using a polysilicon layer as optical interfaces suffer from high losses. We applied the organic compound materials on the silicon-based framework within the optical signal propagation path to form the optical interfaces. In this paper, we have shown low losses in the optical signal processing and feasibility of building a thin-film Fabry-Perot filter. We discussed the optical filter designs, mechanical design, actuation mechanism, fabrication issues, optical measurements, and results.

Silicone Mastitis in “Topless” Waitresses and Some Other Varieties of Foreign-body Mastitis

PubMed Central

Symmers, W. St. C.

1968-01-01

Three cases of disfiguring prosthetogenic mastitis are reported. In two of the cases repeated injections of silicone fluid were followed by extensive bilateral granulomatous mastitis. The axillary lymph nodes were enlarged in both cases: in one of them a node was examined histologically and showed a remarkable proliferation of vacuolated histiocytes in the sinuses and medulla. Both patients had worked in “topless restaurants” and had been obliged to seek artificial means to maintain the excessively large bust that was necessary in that environment. The third patient's mastitis followed implantation of polyethylene prostheses designed to be varied in bulk by injection or withdrawal of saline. A foreign-body reaction developed round the prostheses. In addition, a sinus developed in a needle track on one side; this was accompanied by a local fungal and bacterial infection (Rhizopus species and Pseudomonas pyocyanea respectively). The indications for introducing foreign materials into the breasts to augment their size have to be weighed against the potential dangers that such procedures bring. The biological effects of injected silicones, particularly their long-term effects, are very imperfectly known. Statements implying that these compounds are harmless when injected are not correct. Among the hazards are (a) local sclerosing granulomatous reactions with permanent scarring, (b) histiocytosis secondary to carriage of silicones from their site of inoculation to regional lymph nodes and possibly to other parts of the lymphoreticular system, and, perhaps, (c) carcinogenic activity. ImagesFig. 1Fig. 2Fig. 3Fig. 4Fig. 5Fig. 6 PMID:5690841

Detection of nitroaromatics in the solid, solution, and vapor phases using silicon quantum dot sensors

NASA Astrophysics Data System (ADS)

Nguyen, An; Gonzalez, Christina M.; Sinelnikov, Regina; Newman, W.; Sun, Sarah; Lockwood, Ross; Veinot, Jonathan G. C.; Meldrum, Al

2016-03-01

Silicon quantum dots (Si-QDs) represent a well-known QD fluorophore that can emit throughout the visible spectrum depending on the interface structure and surface functional group. Detection of nitroaromatic compounds by monitoring the luminescence response of the sensor material (typically fluorescent polymers) currently forms the basis of new explosives sensing technologies. Freestanding silicon QDs may represent a benign alternative with a high degree of chemical and physical versatility. Here, we investigate dodecyl and amine-terminated Si-QD luminescence response to the presence of nitrobenzene and dinitrotoluene (DNT) in various solid, solution, and vapor forms. For dinitrotoluene vapor the 3σ detection limit was 6 ppb for monomer-terminated QDs. For nitroaromatics dissolved in toluene the detection limit was on the order of 400 nM, corresponding to ∼100 pg of material distributed over ∼1 cm2 on the sensor surface. Solid traces of nitroaromatics were also easily detectable via a simple ‘touch test’. The samples showed minimal interference effects from common contaminants such as water, ethanol, and acetonitrile. The sensor can be as simple and inexpensive as a small circle of filter paper dipped into a QD solution, with a single vial of QDs able to make hundreds of these sensors. Additionally, a trial fiber-optic sensor device was tested by applying the QDs to one end of a 2 × 2 fiber coupler and exposing them to controlled DNT vapor. Finally, the quenching mechanism was explored via luminescence dynamics measurements and is different for blue (amine) and red (dodecyl) fluorescent silicon QDs.

Fire Resistant, Moisture Barrier Membrane

NASA Technical Reports Server (NTRS)

St.Clair, Terry L. (Inventor)

2000-01-01

A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

Fire Resistant, Moisture Barrier Membrane

NASA Technical Reports Server (NTRS)

St.Clair, Terry L. (Inventor)

1998-01-01

A waterproof and breathable, fire-resistant laminate is provided for use in tents, garments, shoes, and covers, especially in industrial, military and emergency situations. The laminate permits water vapor evaporation while simultaneously preventing liquid water penetration. Further, the laminate is fire-resistant and significantly reduces the danger of toxic compound production when exposed to flame or other high heat source. The laminate may be applied to a variety of substrates and is comprised of a silicone rubber and plurality of fire-resistant, inherently thermally-stable polyimide particles.

Study of the Electronic Surface States of III-V Compounds and Silicon.

DTIC Science & Technology

1981-03-31

region in metal/Si interfaces is thus at most a quantitative , with increasing intermixing going from Ag/Si, Cu/Si, Ni/Si, PdSi to Au/Si. This...to- At the present time, the above argument on cross sections noise ratio better than 102. can not be put in a completely quantitative way since the...of the intensity (0 - 23 in Fig. 2) when the system search effort (also theoretical) is made for a more quantitative becomes richer in the metal

Experimental Study of the Oxidation, Ignition, and Soot Formation Characteristics of Jet Fuel

DTIC Science & Technology

2010-09-29

section and controls the heat flux applied to six heated zones along the 4.11 m long driven section, and 2.5 cm thick mineral wool insulation that...The mixing manifold was insulated with 1.1 cm thick silicon foam rubber insulation, and the mixing vessel was insulated with 2.5 cm- thick mineral ... wool insulation. Experimental work for a number of compounds with variation in manifold and tank heating showed no observable difference in measured

Results of an analytical study of spacecraft deposition contamination by internal reflection spectroscopy. [(haze on spacecraft windows from space debris)

NASA Technical Reports Server (NTRS)

Mookherji, T.

1976-01-01

Outgassing, deposition, and desorption kinetics of silicone compounds, are examined as examples of optical surface contaminants of spacecraft windows. Their behavior in a space environment after exposure to ultraviolet radiation is also examined. The use of internal reflection spectroscopy is shown to provide a viable means of real-time, in-situ identification of contaminants of orbiting spacecraft. The instrumental techniques are proposed as the basis of further investigations and the development of flight hardware.

Process for Preparing Epoxy-Reinforced Silica Aerogels

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B (Inventor)

2016-01-01

One-pot reaction process for preparing epoxy-reinforced monolithic silica aerogels comprising the reaction of at least one silicon compound selected from the group consisting of alkoxysilanes, orthosilicates and combination thereof in any ratio with effective amounts of an epoxy monomer and an aminoalkoxy silane to obtain an epoxy monomer-silica sol in solution, subsequently preparing an epoxy-monomer silica gel from said silica sol solution followed by initiating polymerization of the epoxy monomer to obtain the epoxy-reinforced monolithic silica aerogel.

Studies of Silicon-Refractory Metal Interfaces: Photoemission Study of Interface Formation and Compound Nucleation.

DTIC Science & Technology

1984-10-29

Photoelectron energy analysis was done with Si s states 10--14 eV below E,. For CoSi2 and NiSi2, a commercial double-pass electron energy analyzer . The...Collaborative studies with theorists gave rise to modeling ,f interfaces and calculation of electronic energy states for ordered silicides. (i, ,I... analyzed by a double-pass cylindrical mirror energy A. There is no evidence of Cr outdiffusion into the Au analyzer , and the overall resolution

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Instrumentation Automation for Concrete Structures. Report 2. Automation Hardware and Retrofitting Techniques.

DTIC Science & Technology

1987-06-01

head. The electrical connection points are embedded in silicone sealing compound. The photo elements are varnished; the mirrors are chromium-plated metal...control of barrage walls and retaining dams using reversible pendulums, the suspension points of which are located in boreholes deep under the structure in...rock layers that can very probably be considered as invariable relation points . A measuring device installed in the foundation area of a barrage wall

Structure analysis of aluminium silicon manganese nitride precipitates formed in grain-oriented electrical steels

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

Bernier, Nicolas, E-mail: n.bernier@yahoo.fr; Xhoffer, Chris; Van De Putte, Tom, E-mail: tom.vandeputte@arcelormittal.com

We report a detailed structural and chemical characterisation of aluminium silicon manganese nitrides that act as grain growth inhibitors in industrially processed grain-oriented (GO) electrical steels. The compounds are characterised using energy dispersive X-ray spectrometry (EDX) and energy filtered transmission electron microscopy (EFTEM), while their crystal structures are analysed using X-ray diffraction (XRD) and TEM in electron diffraction (ED), dark-field, high-resolution and automated crystallographic orientation mapping (ACOM) modes. The chemical bonding character is determined using electron energy loss spectroscopy (EELS). Despite the wide variation in composition, all the precipitates exhibit a hexagonal close-packed (h.c.p.) crystal structure and lattice parameters ofmore » aluminium nitride. The EDX measurement of ∼ 900 stoichiometrically different precipitates indicates intermediate structures between pure aluminium nitride and pure silicon manganese nitride, with a constant Si/Mn atomic ratio of ∼ 4. It is demonstrated that aluminium and silicon are interchangeably precipitated with the same local arrangement, while both Mn{sup 2+} and Mn{sup 3+} are incorporated in the h.c.p. silicon nitride interstitial sites. The oxidation of the silicon manganese nitrides most likely originates from the incorporation of oxygen during the decarburisation annealing process, thus creating extended planar defects such as stacking faults and inversion domain boundaries. The chemical composition of the inhibitors may be written as (AlN){sub x}(SiMn{sub 0.25}N{sub y}O{sub z}){sub 1−x} with x ranging from 0 to 1. - Highlights: • We study the structure of (Al,Si,Mn)N inhibitors in grain oriented electrical steels. • Inhibitors have the hexagonal close-packed symmetry with lattice parameters of AlN. • Inhibitors are intermediate structures between pure AlN and (Si,Mn)N with Si/Mn ∼ 4. • Al and Si share the same local arrangement; Mn is incorporated in both Mn{sup 2+} and Mn{sup 3+}. • Oxygen incorporation is invoked to account for the thermal stability of (Al,Si,Mn)N.« less

The efficacy of a scaffold-free Bio 3D conduit developed from human fibroblasts on peripheral nerve regeneration in a rat sciatic nerve model.

PubMed

Yurie, Hirofumi; Ikeguchi, Ryosuke; Aoyama, Tomoki; Kaizawa, Yukitoshi; Tajino, Junichi; Ito, Akira; Ohta, Souichi; Oda, Hiroki; Takeuchi, Hisataka; Akieda, Shizuka; Tsuji, Manami; Nakayama, Koichi; Matsuda, Shuichi

2017-01-01

Although autologous nerve grafting is the gold standard treatment of peripheral nerve injuries, several alternative methods have been developed, including nerve conduits that use supportive cells. However, the seeding efficacy and viability of supportive cells injected in nerve grafts remain unclear. Here, we focused on a novel completely biological, tissue-engineered, scaffold-free conduit. We developed six scaffold-free conduits from human normal dermal fibroblasts using a Bio 3D Printer. Twelve adult male rats with immune deficiency underwent mid-thigh-level transection of the right sciatic nerve. The resulting 5-mm nerve gap was bridged using 8-mm Bio 3D conduits (Bio 3D group, n = 6) and silicone tube (silicone group, n = 6). Several assessments were conducted to examine nerve regeneration eight weeks post-surgery. Kinematic analysis revealed that the toe angle to the metatarsal bone at the final segment of the swing phase was significantly higher in the Bio 3D group than the silicone group (-35.78 ± 10.68 versus -62.48 ± 6.15, respectively; p < 0.01). Electrophysiological studies revealed significantly higher compound muscle action potential in the Bio 3D group than the silicone group (53.60 ± 26.36% versus 2.93 ± 1.84%; p < 0.01). Histological and morphological studies revealed neural cell expression in all regions of the regenerated nerves and the presence of many well-myelinated axons in the Bio 3D group. The wet muscle weight of the tibialis anterior muscle was significantly higher in the Bio 3D group than the silicone group (0.544 ± 0.063 versus 0.396 ± 0.031, respectively; p < 0.01). We confirmed that scaffold-free Bio 3D conduits composed entirely of fibroblast cells promote nerve regeneration in a rat sciatic nerve model.

The efficacy of a scaffold-free Bio 3D conduit developed from human fibroblasts on peripheral nerve regeneration in a rat sciatic nerve model

PubMed Central

Yurie, Hirofumi; Ikeguchi, Ryosuke; Aoyama, Tomoki; Kaizawa, Yukitoshi; Tajino, Junichi; Ito, Akira; Ohta, Souichi; Oda, Hiroki; Takeuchi, Hisataka; Akieda, Shizuka; Tsuji, Manami; Nakayama, Koichi; Matsuda, Shuichi

2017-01-01

Background Although autologous nerve grafting is the gold standard treatment of peripheral nerve injuries, several alternative methods have been developed, including nerve conduits that use supportive cells. However, the seeding efficacy and viability of supportive cells injected in nerve grafts remain unclear. Here, we focused on a novel completely biological, tissue-engineered, scaffold-free conduit. Methods We developed six scaffold-free conduits from human normal dermal fibroblasts using a Bio 3D Printer. Twelve adult male rats with immune deficiency underwent mid-thigh-level transection of the right sciatic nerve. The resulting 5-mm nerve gap was bridged using 8-mm Bio 3D conduits (Bio 3D group, n = 6) and silicone tube (silicone group, n = 6). Several assessments were conducted to examine nerve regeneration eight weeks post-surgery. Results Kinematic analysis revealed that the toe angle to the metatarsal bone at the final segment of the swing phase was significantly higher in the Bio 3D group than the silicone group (-35.78 ± 10.68 versus -62.48 ± 6.15, respectively; p < 0.01). Electrophysiological studies revealed significantly higher compound muscle action potential in the Bio 3D group than the silicone group (53.60 ± 26.36% versus 2.93 ± 1.84%; p < 0.01). Histological and morphological studies revealed neural cell expression in all regions of the regenerated nerves and the presence of many well-myelinated axons in the Bio 3D group. The wet muscle weight of the tibialis anterior muscle was significantly higher in the Bio 3D group than the silicone group (0.544 ± 0.063 versus 0.396 ± 0.031, respectively; p < 0.01). Conclusions We confirmed that scaffold-free Bio 3D conduits composed entirely of fibroblast cells promote nerve regeneration in a rat sciatic nerve model. PMID:28192527

Method for detection of extremely low concentration

DOEpatents

Andresen, Brian D.; Miller, Fred S.

2002-01-01

An ultratrace detector system for hand-held gas chromatography having high sensitivity, for example, to emissions generated during production of weapons, biological compounds, drugs, etc. The detector system is insensitive to water, air, helium, argon, oxygen, and CO.sub.2. The detector system is basically composed of a hand-held capillary gas chromatography (GC), an insulated heated redox-chamber, a detection chamber, and a vapor trap. For example, the detector system may use gas phase redox reactions and spectral absorption of mercury vapor. The gas chromatograph initially separates compounds that percolate through a bed of heated mercuric oxide (HgO) in a silica--or other metal--aerogel material which acts as an insulator. Compounds easily oxidized by HgO liberate atomic mercury that subsequently pass through a detection chamber which includes a detector cell, such as quartz, that is illuminated with a 254 nm ultra-violet (UV) mercury discharge lamp which generates the exact mercury absorption bands that are used to detect the liberated mercury atoms. Atomic mercury strongly absorbs 254 nm energy is therefore a specific signal for reducing compounds eluting from the capillary GC, whereafter the atomic mercury is trapped for example, in a silicon-aerogel trap.

Ultratrace detector for hand-held gas chromatography

DOEpatents

Andresen, Brian D.; Miller, Fred S.

1999-01-01

An ultratrace detector system for hand-held gas chromatography having high sensitivity, for example, to emissions generated during production of weapons, biological compounds, drugs, etc. The detector system is insensitive to water, air, helium, argon, oxygen, and C0.sub.2. The detector system is basically composed of a hand-held capillary gas chromatography (GC), an insulated heated redox-chamber, a detection chamber, and a vapor trap. For example, the detector system may use gas phase redox reactions and spectral absorption of mercury vapor. The gas chromatograph initially separates compounds that percolate through a bed of heated mercuric oxide (HgO) in a silica--or other metal--aerogel material which acts as an insulator. Compounds easily oxidized by HgO liberate atomic mercury that subsequently pass through a detection chamber which includes a detector cell, such as quartz, that is illuminated with a 254 nm ultra-violet (UV) mercury discharge lamp which generates the exact mercury absorption bands that are used to detect the liberated mercury atoms. Atomic mercury strongly absorbs 254 nm energy is therefore a specific signal for reducing compounds eluting from the capillary GC, whereafter the atomic mercury is trapped for example, in a silicon-aerogel trap.

Investigating the coffee flavour in South African Pinotage wine using novel offline olfactometry and comprehensive gas chromatography with time of flight mass spectrometry.

PubMed

Naudé, Yvette; Rohwer, Egmont R

2013-01-04

Pinotage wine from several South African wine cellars has been produced with a novel coffee flavour. We have investigated this innovative coffee effect using in house developed solventless sampling and fractionating olfactometric techniques, which are unique in their ability to study synergistic aroma effects as opposed to traditional gas chromatography olfactometry (GC-O) which is designed to, ideally, evaluate single eluting compounds in a chromatographic sequence. Sections of the chromatogram, multiple or single peaks, were recaptured on multichannel open tubular silicone rubber (polydimethylsiloxane (PDMS)) traps at the end of a GC column. The recaptured fractions were released in a controlled manner for offline olfactory evaluation, and for qualitative analysis using comprehensive gas chromatography coupled to time of flight mass spectrometry (GC×GC-TOFMS) for compound separation and identification, thus permitting correlation of odour with specific compounds. A combination of furfural and 2-furanmethanol was responsible for a roast coffee bean-like odour in coffee style Pinotage wines. This coffee perception is the result of a synergistic effect in which no individual compound was responsible for the characteristic aroma. Copyright © 2012 Elsevier B.V. All rights reserved.

Thermal noise and optomechanical features in the emission of a membrane-coupled compound cavity laser diode.

PubMed

Baldacci, Lorenzo; Pitanti, Alessandro; Masini, Luca; Arcangeli, Andrea; Colangelo, Francesco; Navarro-Urrios, Daniel; Tredicucci, Alessandro

2016-08-19

We demonstrate the use of a compound optical cavity as linear displacement detector, by measuring the thermal motion of a silicon nitride suspended membrane acting as the external mirror of a near-infrared Littrow laser diode. Fluctuations in the laser optical power induced by the membrane vibrations are collected by a photodiode integrated within the laser, and then measured with a spectrum analyzer. The dynamics of the membrane driven by a piezoelectric actuator is investigated as a function of air pressure and actuator displacement in a homodyne configuration. The high Q-factor (~3.4 · 10(4) at 8.3 · 10(-3) mbar) of the fundamental mechanical mode at ~73 kHz guarantees a detection sensitivity high enough for direct measurement of thermal motion at room temperature (~87 pm RMS). The compound cavity system here introduced can be employed as a table-top, cost-effective linear displacement detector for cavity optomechanics. Furthermore, thanks to the strong optical nonlinearities of the laser compound cavity, these systems open new perspectives in the study of non-Markovian quantum properties at the mesoscale.

Thermal noise and optomechanical features in the emission of a membrane-coupled compound cavity laser diode

PubMed Central

Baldacci, Lorenzo; Pitanti, Alessandro; Masini, Luca; Arcangeli, Andrea; Colangelo, Francesco; Navarro-Urrios, Daniel; Tredicucci, Alessandro

2016-01-01

We demonstrate the use of a compound optical cavity as linear displacement detector, by measuring the thermal motion of a silicon nitride suspended membrane acting as the external mirror of a near-infrared Littrow laser diode. Fluctuations in the laser optical power induced by the membrane vibrations are collected by a photodiode integrated within the laser, and then measured with a spectrum analyzer. The dynamics of the membrane driven by a piezoelectric actuator is investigated as a function of air pressure and actuator displacement in a homodyne configuration. The high Q-factor (~3.4 · 104 at 8.3 · 10−3 mbar) of the fundamental mechanical mode at ~73 kHz guarantees a detection sensitivity high enough for direct measurement of thermal motion at room temperature (~87 pm RMS). The compound cavity system here introduced can be employed as a table-top, cost-effective linear displacement detector for cavity optomechanics. Furthermore, thanks to the strong optical nonlinearities of the laser compound cavity, these systems open new perspectives in the study of non-Markovian quantum properties at the mesoscale. PMID:27538586

Co-delivery of a hydrophobic small molecule and a hydrophilic peptide by porous silicon nanoparticles.

PubMed

Liu, Dongfei; Bimbo, Luis M; Mäkilä, Ermei; Villanova, Francesca; Kaasalainen, Martti; Herranz-Blanco, Barbara; Caramella, Carla M; Lehto, Vesa-Pekka; Salonen, Jarno; Herzig, Karl-Heinz; Hirvonen, Jouni; Santos, Hélder A

2013-09-10

Nanoparticulate drug delivery systems offer remarkable opportunities for clinical treatment. However, there are several challenges when they are employed to deliver multiple cargos/payloads, particularly concerning the synchronous delivery of small molecular weight drugs and relatively larger peptides. Since porous silicon (PSi) nanoparticles (NPs) can easily contain high payloads of drugs with various properties, we evaluated their carrier potential in multi-drug delivery for co-loading of the hydrophobic drug indomethacin and the hydrophilic human peptide YY3-36 (PYY3-36). Sequential loading of these two drugs into the PSi NPs enhanced the drug release rate of each drug and also their amount permeated across Caco-2 and Caco-2/HT29 cell monolayers. Regardless of the loading approach used, dual or single, the drug permeation profiles were in good correlation with their drug release behaviour. Furthermore, the permeation studies indicated the critical role of the mucus intestinal layer and the paracellular resistance in the permeation of the therapeutic compounds across the intestinal wall. Loading with PYY3-36 also greatly improved the cytocompatibility of the PSi NPs. Conformational analysis indicated that the PYY3-36 could still display biological activity after release from the PSi NPs and permeation across the intestinal cell monolayers. These results are the first demonstration of the promising potential of PSi NPs for simultaneous multi-drug delivery of both hydrophobic and hydrophilic compounds. Copyright © 2013 Elsevier B.V. All rights reserved.

Improved room-temperature luminescence of core-shell InGaAs/GaAs nanopillars via lattice-matched passivation

NASA Astrophysics Data System (ADS)

Komolibus, Katarzyna; Scofield, Adam C.; Gradkowski, Kamil; Ochalski, Tomasz J.; Kim, Hyunseok; Huffaker, Diana L.; Huyet, Guillaume

2016-02-01

Optical properties of GaAs/InGaAs/GaAs nanopillars (NPs) grown on GaAs(111)B were investigated. Employment of a mask-etching technique allowed for an accurate control over the geometry of NP arrays in terms of both their diameter and separation. This work describes both the steady-state and time-resolved photoluminescence of these structures as a function of the ensemble geometry, composition of the insert, and various shell compounds. The effects of the NP geometry on a parasitic radiative recombination channel, originating from an overgrown lateral sidewall layer, are discussed. Optical characterization reveals a profound influence of the core-shell lattice mismatch on the carrier lifetime and emission quenching at room temperature. When the lattice-matching conditions are satisfied, an efficient emission from the NP arrays at room temperature and below the band-gap of silicon is observed, clearly highlighting their potential application as emitters in optical interconnects integrated with silicon platforms.

Dibenzosiloles and 12H-indololo[3,2-d]naphtho[1,2-b][1]siloles: exploration of organic chromophores exhibiting efficient solid-state fluorescence.

PubMed

Shimizu, Masaki

2015-02-01

The construction of a diorganosilylene bridge over a biaryl moiety at the 2,2'-positions is a versatile strategy for fine-tuning its HOMO-LUMO energy gap, which is closely linked to the electronic and optical properties of the compounds. Therefore, there is growing interest in the use of silicon-bridged biaryl motifs as key cores of various types of advanced functional materials, such as light-emitting, semiconducting, photovoltaic, and sensing materials. To accelerate the advances of materials based on silicon-bridged biaryls, it is essential to create new classes of biaryls and explore their functions and properties. This Personal Account describes recent research on the development of organic chromophores based on functionalized dibenzosiloles and 12H-indololo[3,2-d]naphtho[1,2-b][1]siloles as solid-state emitters. Copyright © 2014 The Chemical Society of Japan and Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

A readout circuit dedicated for the detection of chemiluminescence using a silicon photomultiplier

NASA Astrophysics Data System (ADS)

Baszczyk, M.; Dorosz, P.; Mik, L.; Kucewicz, W.; Reczynski, W.; Sapor, M.

2018-05-01

A readout circuit dedicated for the detection of the chemiluminescence phenomenon using a silicon photomultiplier (SiPM) is presented. During chemiluminescence, light is generated as a result of chemical reaction. Chemiluminescence is used in many applications within medicine, chemistry, biology and biotechnology, and is one of the most important sensing techniques in biomedical science and clinical medicine. The front-end electronics consist of a preamplifier and a fast shaper—this produces pulses, the peaking time which is 3.6 ns for a single photon and the FWHM is 3.8 ns. The system has been optimised to measure chemiluminescence—it is sensitive at the level of single photons, it generates a low number of overlapping pulses and is accurate. Two methods of signal detection are analysed and compared: the counting of events and amplitude detection. The relationship between the chemiluminescence light intensity and the concentration of the chemical compound (luminol) is linear in the range of the tested concentrations and has strong linearity parameters and low prediction intervals.

Electrochemically driven three-phase interlines into insulator compounds: electroreduction of solid SiO2 in molten CaCl2.

PubMed

Xiao, Wei; Jin, Xianbo; Deng, Yuan; Wang, Dihua; Hu, Xiaohong; Chen, George Z

2006-08-11

The electrochemical reduction of solid SiO2 (quartz) to Si is studied in molten CaCl2 at 1173 K. Experimental observations are compared and agree well with a novel penetration model in relation with electrochemistry at the dynamic conductor|insulator|electrolyte three-phase interlines. The findings show that the reduction of a cylindrical quartz pellet at certain potentials is mainly determined by the diffusion of the O(2-) ions and also the ohmic polarisation in the reduction-generated porous silicon layer. The reduction rate increases with the overpotential to a maximum after which the process is retarded, most likely due to precipitation of CaO in the reaction region (cathodic passivation). Data are reported on the reduction rate, current efficiency and energy consumption during the electroreduction of quartz under potentiostatic conditions. These theoretical and experimental findings form the basis for an in-depth discussion on the optimisation of the electroreduction method for the production of silicon.

Effect of axial ligands on the molecular configurations, stability, reactivity, and photodynamic activities of silicon phthalocyanines.

PubMed

Luan, Liqiang; Ding, Lanlan; Shi, Jiawei; Fang, Wenjuan; Ni, Yuxing; Liu, Wei

2014-12-01

To demonstrate the effect of axial ligands on the structure-activity relationship, a series of axially substituted silicon phthalocyanines (SiPcs) have been synthesized with changes to the axial ligands. The reactivity of the axial ligand upon shielding by the phthalocyanine ring current, along with their stability, photophysical, and photodynamic therapy (PDT) activities were compared and evaluated for the first time. As revealed by single-crystal XRD analysis, rotation of the axial -OMe ligands was observed in SiPc 3, which resulted in two molecular configurations coexisting synchronously in both the solid and solution states and causing a split of the phthalocyanine α protons in the (1)H NMR spectra that is significantly different from all SiPcs reported so far. The remarkable photostability, good singlet oxygen quantum yield, and efficient in vitro photodynamic activity synergistically show that compound 3 is one of the most promising photosensitizers for PDT. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation of Multiwalled Carbon Nanotubes/Hydroxyl-Terminated Silicone Oil Fiber and Its Application to Analysis of Crude Oils

PubMed Central

Tong, Ting; Zhang, Wanfeng; Dai, Wei; He, Sheng; Chang, Zhenyang; Gao, Xuanbo

2014-01-01

A simple and efficient method to analyze the volatile and semivolatile organic compounds in crude oils has been developed based on direct immersion solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (DI-SPME-GC × GC/TOFMS). A novel fiber, multiwalled carbon nanotubes/hydroxyl-terminated silicone oil (MWNTs-TSO-OH), was prepared by sol-gel technology. Using standard solutions, the extraction conditions were optimized such as extraction mode, extraction temperature, extraction time, and salts effect. With the optimized conditions, a real crude oil sample was extracted and then analyzed in detail. It shows that the proposed method is very effective in simultaneously analyzing the normal and branched alkanes, cycloalkanes, aromatic hydrocarbons, and biomarkers of crude oil such as steranes and terpanes. Furthermore, the method showed good linearity (r > 0.999), precision (RSD < 8%), and detection limits ranging from 0.2 to 1.6 ng/L. PMID:24578659

Shuttle orbiter TPS flight repair kit development

NASA Technical Reports Server (NTRS)

1979-01-01

The design and application of a TPS repair kit is presented. The repair kit is designed for on orbit use by a crew member working in the manned maneuvering unit (MMU). The kit includes the necessary equipment and materials to accomplish the repair tasks which include the following: HRSI emittance coating repair, damaged tile repair, missing tile repair, and multiple tile repair. Two types of repair materials required to do the small area repair and the large area repair are described. The materials area cure in place, silicone base ablator for small damaged areas and precured ablator tile for repair of larger damaged areas is examined. The cure in place ablator is also used as an adhesive to bond the precured tiles in place. An applicator for the cure in place ablator, designed to contain a two-part silicon compound, mix the two components at correct ratio, and dispense the materials at rates compatible with mission timelines established for the EVA is described.

Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

DOEpatents

Carr,; Jeffrey, W [Livermore, CA

2009-03-31

Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

MoSi2-Base Structural Composite Passed Engine Test

NASA Technical Reports Server (NTRS)

Nathal, Michael V.; Hebsur, Mohan G.

1999-01-01

The intermetallic compound molybdenum disilicide (MoSi2) is an attractive high-temperature structural material for advanced engine applications. It has excellent oxidation resistance, a high melting point, relatively low density, and high thermal conductivity; and it is easily machined. Past research at the NASA Lewis Research Center has resulted in the development of a hybrid composite consisting of a MoSi2 matrix reinforced with silicon nitride (Si3N4) particulate and silicon carbide (SiC) fibers. This composite has demonstrated attractive strength, toughness, thermal fatigue, and oxidation resistance, including resistance to "pest" oxidation. These properties attracted the interest of the Office of Naval Research and Pratt & Whitney, and a joint NASA/Navy/Pratt & Whitney effort was developed to continue to mature the MoSi2 composite technology. A turbine blade outer air seal, which was part of the Integrated High Performance Turbine Engine Technology (IHPTET) program, was chosen as a first component on which to focus.

Aluminum Alloy and Article Cast Therefrom

NASA Technical Reports Server (NTRS)

Lee, Jonathan A. (Inventor); Chen, Po-Shou (Inventor)

2003-01-01

A cast article from an aluminum alloy, which has improved mechanical properties at elevated temperatures, has the following composition in weight percent: Silicon 14 - 25.0, Copper 5.5 - 8.0, Iron 0.05 - 1.2, Magnesium 0.5 - 1.5, Nickel 0.05 - 0.9, Manganese 0.05 - 1.0, Titanium 0.05 - 1.2, Zirconium 0.05 - 1.2, Vanadium 0.05 - 1.2, Zinc 0.05 - 0.9, Phosphorus 0.001 - 0.1, and the balance is Aluminum, wherein the silicon-to-magnesium ratio is 10 - 25, and the copper-to-magnesium ratio is 4 - 15. The aluminum alloy contains a simultaneous dispersion of three types of Al3X compound particles (X=Ti, V, Zr) having a LI2, crystal structure, and their lattice parameters are coherent to the aluminum matrix lattice. A process for producing this cast article is also disclosed, as well as a metal matrix composite, which includes the aluminum alloy serving as a matrix and containing up to about 60% by volume of a secondary filler material.

Development of High Precision Metal Micro-Electro-Mechanical-Systems Column for Portable Surface Acoustic Wave Gas Chromatograph

NASA Astrophysics Data System (ADS)

Iwaya, Takamitsu; Akao, Shingo; Sakamoto, Toshihiro; Tsuji, Toshihiro; Nakaso, Noritaka; Yamanaka, Kazushi

2012-07-01

In the field of environmental measurement and security, a portable gas chromatograph (GC) is required for the on-site analysis of multiple hazardous gases. Although the gas separation column has been downsized using micro-electro-mechanical-systems (MEMS) technology, an MEMS column made of silicon and glass still does not have sufficient robustness and a sufficiently low fabrication cost for a portable GC. In this study, we fabricated a robust and inexpensive high-precision metal MEMS column by combining diffusion-bonded etched stainless-steel plates with alignment evaluation using acoustic microscopy. The separation performance was evaluated using a desktop GC with a flame ionization detector and we achieved the high separation performance comparable to the best silicon MEMS column fabricated using a dynamic coating method. As an application, we fabricated a palm-size surface acoustic wave (SAW) GC combining this column with a ball SAW sensor and succeeded in separating and detecting a mixture of volatile organic compounds.

Determination of diffusion coefficients of biocides on their passage through organic resin-based renders.

PubMed

Styszko, Katarzyna; Kupiec, Krzysztof

2016-10-01

In this study the diffusion coefficients of isoproturon, diuron and cybutryn in acrylate and silicone resin-based renders were determined. The diffusion coefficients were determined using measuring concentrations of biocides in the liquid phase after being in contact with renders for specific time intervals. The mathematical solution of the transient diffusion equation for an infinite plate contacted on one side with a limited volume of water was used to calculate the diffusion coefficient. The diffusion coefficients through the acrylate render were 8.10·10(-9) m(2) s(-1) for isoproturon, 1.96·10(-9) m(2) s(-1) for diuron and 1.53·10(-9) m(2) s(-1) for cybutryn. The results for the silicone render were lower by one order of magnitude. The compounds with a high diffusion coefficient for one polymer had likewise high values for the other polymer. Copyright © 2016 Elsevier Ltd. All rights reserved.

Saw-tooth refractive x-ray optics with sub-micron resolution

NASA Astrophysics Data System (ADS)

Cederstrom, Bjorn; Ribbing, Carolina; Lundqvist, Mats

2002-11-01

Saw-tooth refractive x-ray lenses have been used to focus a synchrotron beam to sub-μm line width. These lenses are free from spherical aberration and work in analogy with 1-D focusing parabolic compound refractive lenses. However, the focal length can be varied by a simple mechanical procedure. Silicon lenses were fabricated by wet anisotropic etching, and epoxy replicas were molded from the silicon masters. Theses lenses provided 1-D intensity gains up to a factor of 40 and the smallest focal line width was 0.74 μm, very close to the theoretical expectation. Two crossed lenses were put in series to obtain 2-D focusing and the 80 μm by 275 μm source was imaged to 1.0 μm by 5.4 μm. Beryllium lenses were fabricated using conventional computer-controlled milling. The focal line width was 1.7 μm, nearly 3 times larger than predicted by theory. This can be attributed to large surface roughness and a bent lens shape.

Interaction of bombesin and its fragments with gold nanoparticles analyzed using surface-enhanced Raman spectroscopy

NASA Astrophysics Data System (ADS)

Tąta, Agnieszka; Szkudlarek, Aleksandra; Kim, Younkyoo; Proniewicz, Edyta

2017-02-01

This work demonstrates the application of commercially available stable surface composed of gold nanograins with diameters ranging from 70 to 226 nm deposited onto silicon wafer for surface-enhanced Raman scattering investigations of biologically active compounds, such as bombesin (BN) and its fragments. BN is an important neurotransmitter involved in a complex signaling pathways and biological responses; for instance, hypertensive action, contractive on uterus, colon or ileum, locomotor activity, stimulation of gastric and insulin secretion as well as growth promotion of various tumor cell lines, including: lung, prostate, stomach, colon, and breast. It has also been shown that 8-14 BN C-terminal fragment partially retains the biological activity of BN. The SERS results for BN and its fragment demonstrated that (1) three amino acids from these peptides sequence; i.e., L-histidine, L-methionine, and L-tryptophan, are involved in the interaction with gold coated silicon wafer and (2) the strength of these interactions depends upon the aforementioned amino acids position in the peptide sequence.

Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi2/Si)

PubMed Central

Nomoev, Andrey V.; Bardakhanov, Sergey P.; Schreiber, Makoto; Bazarova, Dashima Zh.; Baldanov, Boris B.; Romanov, Nikolai A.

2014-01-01

Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi2/Si) were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), selective area electron diffraction (SAED), and energy dispersive X-ray fluorescence (EDX) analysis. The system is compared to previously synthesized core-shell type particles in order to show possible differences responsible for the Janus-like structure forming instead of a core-shell architecture. It is proposed that the production of Janus-like as opposed to core-shell or monophase particles occurs due to the ability of Ta and Si to form compounds and the relative content of Ta and Si atoms in the produced vapour. Based on the results, a potential mechanism of formation for the TaSi2/Si nanoparticles is discussed. PMID:28346996

Synthesis, Characterization, and Mechanism of Formation of Janus-Like Nanoparticles of Tantalum Silicide-Silicon (TaSi₂/Si).

PubMed

Nomoev, Andrey V; Bardakhanov, Sergey P; Schreiber, Makoto; Bazarova, Dashima Zh; Baldanov, Boris B; Romanov, Nikolai A

2014-12-25

Metal-semiconductor Janus-like nanoparticles with the composition tantalum silicide-silicon (TaSi₂/Si) were synthesized for the first time by means of an evaporation method utilizing a high-power electron beam. The composition of the synthesized particles were characterized using high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), selective area electron diffraction (SAED), and energy dispersive X-ray fluorescence (EDX) analysis. The system is compared to previously synthesized core-shell type particles in order to show possible differences responsible for the Janus-like structure forming instead of a core-shell architecture. It is proposed that the production of Janus-like as opposed to core-shell or monophase particles occurs due to the ability of Ta and Si to form compounds and the relative content of Ta and Si atoms in the produced vapour. Based on the results, a potential mechanism of formation for the TaSi₂/Si nanoparticles is discussed.

Multilayer photosensitive structures based on porous silicon and rare-earth-element compounds: Study of spectral characteristics

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

Kirsanov, N. Yu.; Latukhina, N. V., E-mail: natalat@yandex.ru; Lizunkova, D. A.

2017-03-15

The spectral characteristics of the specular reflectance, photosensitivity, and photoluminescence (PL) of multilayer structures based on porous silicon with rare-earth-element (REE) ions are investigated. It is shown that the photosensitivity of these structures in the wavelength range of 0.4–1.0 μm is higher than in structures free of REEs. The structures with Er{sup 3+} ions exhibit a luminescence response at room temperature in the spectral range from 1.1 to 1.7 μm. The PL spectrum of the erbium impurity is characterized by a fine line structure, which is determined by the splitting of the {sup 4}I{sub 15/2} multiplet of the Er{sup 3+}more » ion. It is shown that the structures with a porous layer on the working surface have a much lower reflectance in the entire spectral range under study (0.2–1.0 μm).« less

TEM Analysis of Diffusion-Bonded Silicon Carbide Ceramics Joined Using Metallic Interlayers

NASA Technical Reports Server (NTRS)

Ozaki, T.; Hasegawa, Y.; Tsuda, H.; Mori, S.; Halbig, M. C.; Asthana, R.; Singh, M.

2017-01-01

SiC fiber-bonded ceramics (SA-Tyrannohex: SA-THX) diffusion-bonded with TiCu metallic interlayers were investigated. Thin samples of the ceramics were prepared with a focused ion beam (FIB) and the interfacial microstructure of the prepared samples was studied by transmission electron microscopy (TEM) and scanning TEM (STEM). In addition to conventional microstructure observation, for detailed analysis of reaction compounds in diffusion-bonded area, we performed STEM-EDS measurements and selected area electron diffraction (SAD) experiments. The TEM and STEM experiments revealed the diffusion-bonded area was composed of only one reaction layer, which was characterized by TiC precipitates in Cu-Si compound matrix. This reaction layer was in good contact with the SA-THX substrates, and it is concluded that the joint structure led to the excellent bonding strength.

Some features associated with organosilane groups grafted by the sol-gel process onto synthetic talc-like phyllosilicate.

PubMed

Sales, José A A; Petrucelli, Giovanni C; Oliveira, Fernando J V E; Airoldi, Claudio

2006-05-01

Two new lamellar inorganic-organic magnesium silicates have been successfully synthesized by using sol-gel based processes under mild temperature conditions. The talc-organosilicates derived using two silylating agents as the silicon source, (i) 3-chloropropyltrimethoxysilane, and (ii) from the attachment of 5-amino-1,3,4-thiadiazole-2-thiol molecule to this precursor agent, yielded PhMg-Cl and PhMg-Tz phyllosilicates. These organoclays were characterized through elemental analyses, infrared spectroscopy, X-ray diffractometry, surface area, thermogravimetry, and carbon and silicon solid state nuclear magnetic resonance spectroscopy. The results confirmed the presence of organic moieties covalently bonded to the inorganic silicon sheet network of the 2:1 class of phyllosilicates, with a density of organic molecules of 6.6+/-0.1 and 2.7+/-0.2 mmol g(-1) anchored on the inorganic layer and with interlayer distances of 1158 and 1628 pm, respectively. The nuclear magnetic resonances results in the solid state are in agreement with the sequence of carbons distributed in the pendant chains of the original silylating agents and the silicon bonded to oxygen atoms or carbon atoms of the inorganic sheets, as expected for the organically functionalized phyllosilicates. The enhanced potential of the new compound PhMg-Tz as a multi property material was explored in adsorbing cations from aqueous solution. The basic sulfur and nitrogen centers attached to the pendant chains inside the lamellar cavity can coordinate mercury, by presenting an isotherm saturated at 0.19 mmol g(-1) of this heavy metal. The functionality of this organoclay-like material expresses its potential for heavy cation removal from an ecosystem.

Transfer of InP epilayers by wafer bonding

NASA Astrophysics Data System (ADS)

Hjort, Klas

2004-08-01

Wafer bonding increases the freedom of design in the integration of dissimilar materials. For example, it is interesting to combine III-V compounds that have direct band gap and high mobility with silicon (Si) that is extensively used in microelectronic applications. The interest to integrate III-V-based materials with Si arises primarily from two types of applications: smart pixels for optical intra- and inter-chip interconnects in the so-called optoelectronic integrated circuits, and optoelectronic devices using some material advantages of combining III-V with Si. Also, in the III-V industry larger substrates are crucial for higher efficiency in high-volume production, and especially so for monolithic microwave integrated circuits (MMIC). For indium phosphide (InP) the development of large-area substrates has not been able to keep up with market demands. One way to circumvent this problem is to use silicon substrates that are large-area, low-cost, and mechanically strong with high thermal conductivity. In addition, silicon is transparent at the emission wavelengths most often used in InP-based optoelectronics. Unfortunately, the large lattice-mismatch, 8.1%, between silicon and InP, has limited the success of heteroepitaxial growth. Hence, one alternative to be reviewed is InP-to-Si wafer bonding. When a direct semiconductor interface is not needed there are several other means of wafer bonding, e.g. adhesive, eutectic, and solid-state. These processes can be used for direct integration of small islets of epitaxially thin InP microelectronics onto other substrates, e.g. by transferring of InP-based epilayers to a Si-based microwave circuit by pick-and-place, BCB resist adhesive bonding and sacrificing of the InP substrate.

Singlet oxygen sensitizing materials based on porous silicone: photochemical characterization, effect of dye reloading and application to water disinfection with solar reactors.

PubMed

Manjón, Francisco; Santana-Magaña, Montserrat; García-Fresnadillo, David; Orellana, Guillermo

2010-06-01

Photogeneration of singlet molecular oxygen ((1)O(2)) is applied to organic synthesis (photooxidations), atmosphere/water treatment (disinfection), antibiofouling materials and in photodynamic therapy of cancer. In this paper, (1)O(2) photosensitizing materials containing the dyes tris(4,4'-diphenyl-2,2'-bipyridine)ruthenium(II) (1, RDB(2+)) or tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (2, RDP(2+)), immobilized on porous silicone (abbreviated RDB/pSil and RDP/pSil), have been produced and tested for waterborne Enterococcus faecalis inactivation using a laboratory solar simulator and a compound parabolic collector (CPC)-based solar photoreactor. In order to investigate the feasibility of its reuse, the sunlight-exposed RDP/pSil sensitizing material (RDP/pSil-a) has been reloaded with RDP(2+) (RDP/pSil-r). Surprisingly, results for bacteria inactivation with the reloaded material have demonstrated a 4-fold higher efficiency compared to those of either RDP/pSil-a, unused RDB/pSil and the original RDP/pSil. Surface and bulk photochemical characterization of the new material (RDP/pSil-r) has shown that the bactericidal efficiency enhancement is due to aggregation of the silicone-supported photosensitizer on the surface of the polymer, as evidenced by confocal fluorescence lifetime imaging microscopy (FLIM). Photogenerated (1)O(2) lifetimes in the wet sensitizer-doped silicone have been determined to be ten times longer than in water. These facts, together with the water rheology in the solar reactor and the interfacial production of the biocidal species, account for the more effective disinfection observed with the reloaded photosensitizing material. These results extend and improve the operational lifetime of photocatalytic materials for point-of-use (1)O(2)-mediated solar water disinfection.

Crystallization and growth of Ni-Si alloy thin films on inert and on silicon substrates

NASA Astrophysics Data System (ADS)

Grimberg, I.; Weiss, B. Z.

1995-04-01

The crystallization kinetics and thermal stability of NiSi2±0.2 alloy thin films coevaporated on two different substrates were studied. The substrates were: silicon single crystal [Si(100)] and thermally oxidized silicon single crystal. In situ resistance measurements, transmission electron microscopy, x-ray diffraction, Auger electron spectroscopy, and Rutherford backscattering spectroscopy were used. The postdeposition microstructure consisted of a mixture of amorphous and crystalline phases. The amorphous phase, independent of the composition, crystallizes homogeneously to NiSi2 at temperatures lower than 200 °C. The activation energy, determined in the range of 1.4-2.54 eV, depends on the type of the substrate and on the composition of the alloyed films. The activation energy for the alloys deposited on the inert substrate was found to be lower than for the alloys deposited on silicon single crystal. The lowest activation energy was obtained for nonstoichiometric NiSi2.2, the highest for NiSi2—on both substrates. The crystallization mode depends on the structure of the as-deposited films, especially the density of the existing crystalline nuclei. Substantial differences were observed in the thermal stability of the NiSi2 compound on both substrates. With the alloy films deposited on the Si substrate, only the NiSi2 phase was identified after annealing to temperatures up to 800 °C. In the films deposited on the inert substrate, NiSi and NiSi2 phases were identified when the Ni content in the alloy exceeded 33 at. %. The effects of composition and the type of substrate on the crystallization kinetics and thermal stability are discussed.

Silicon, endophytes and secondary metabolites as grass defenses against mammalian herbivores

PubMed Central

Huitu, Otso; Forbes, Kristian M.; Helander, Marjo; Julkunen-Tiitto, Riitta; Lambin, Xavier; Saikkonen, Kari; Stuart, Peter; Sulkama, Sini; Hartley, Sue

2014-01-01

Grasses have been considered to primarily employ tolerance in lieu of defense in mitigating damage caused by herbivory. Yet a number of mechanisms have been identified in grasses, which may deter feeding by grazers. These include enhanced silicon uptake, hosting of toxin-producing endophytic fungi and induction of secondary metabolites. While these mechanisms have been individually studied, their synergistic responses to grazing, as well as their effects on grazers, are poorly known. A field experiment was carried out in 5 × 5 m outdoor enclosures to quantify phytochemical changes of either endophyte-infected (E+) or endophyte-free (E-) meadow fescue (Schedonorus pratensis) in response to medium intensity (corresponding with densities of ca. 1200 voles/ha for 5 weeks during 3 months) or heavy intensity (ca. 1200 voles/ha for 8 weeks during 3 months) grazing by a mammalian herbivore, the field vole (Microtus agrestis). A laboratory experiment was then conducted to evaluate the effects of endophyte infection status and grazing history of the grass diet on vole performance. As predicted, grazing increased foliar silicon content, by up to 13%. Grazing also increased foliar levels of phosphorous and several phenolic compounds, most notably those of the flavonols isorhamnetin-diglycoside and rhamnetin derivative. Silicon concentrations were consistently circa 16% higher in E+ grasses than in E-grasses, at all levels of grazing. Similarly, concentrations of chlorogenic acid derivative were found to be consistently higher in E+ than in E- grasses. Female voles maintained on heavily grazed grasses suffered higher mortality rates in the laboratory than female voles fed ungrazed grass, regardless of endophyte infection status. Our results conclusively demonstrate that, in addition to tolerance, grasses employ multi-tiered, effective defenses against mammalian grazers. PMID:25278951

Role of atomic bonding for compound and glass formation in Ni-Si, Pd-Si, and Ni-B systems

NASA Astrophysics Data System (ADS)

Tanaka, K.; Saito, T.; Suzuki, K.; Hasegawa, R.

1985-11-01

Valence electronic structures of crystalline compounds and glassy alloys of Ni silicides, Pd silicides, and Ni borides are studied by soft-x-ray spectroscopy over wide ranges of Si and B concentrations. The samples prepared include bulk compounds, glassy ribbons, and amorphous sputtered films. Silicon Kβ emissions of Ni and Pd silicides generally consist of a prominent peak fixed at ~=4.5 and ~=5.8 eV below the Fermi level EF, respectively, with a shoulder near EF which grows and shifts toward lower energy with increasing Si concentration. The former is identified as due to Si p-like states forming Si 3p-Ni 3d or Si 3p-Pd 4d bonding states while the latter as due to the corresponding antibonding states. Ni L3 and Pd L3 emissions of these silicides indicate that Ni 3d and Pd 4d states lie between the above two states. These local electronic configurations are consistent with partial-density-of-states (PDOS) calculations performed by Bisi and Calandra. Similar electronic configurations are suggested for Ni borides from B Kα and Ni L3 emissions. Differences of emission spectra between compounds and glasses of similar compositions are rather small, but some enhancement of the contribution of antibonding states to the PDOS near EF is suggested for certain glasses over that of the corresponding compounds. These features are discussed in connection with the compound stability and glass formability.