Stretch-Orientation of LaRC(TM) RP 50 Polyimide Film

NASA Technical Reports Server (NTRS)

Hawkins, Brian P.; Hinkley, Jeffrey A.; Pater, Ruth H.; Moore, Joanne

2006-01-01

An addition-curable poly(amic acid) film was subjected to various thermal pretreatments and then to uniaxial or biaxial drawing. Hot-stretching to 300% of the initial length produced better than twofold increases in tensile modulus and strength of partially-cured films. Most of the improvement was maintained upon completion of the curing at constant length.

Smoothing Polymer Surfaces by Solvent-Vapor Exposure

NASA Astrophysics Data System (ADS)

Anthamatten, Mitchell

2003-03-01

Ultra-smooth polymer surfaces are of great importance in a large body of technical applications such as optical coatings, supermirrors, waveguides, paints, and fusion targets. We are investigating a simple approach to controlling surface roughness: by temporarily swelling the polymer with solvent molecules. As the solvent penetrates into the polymer, its viscosity is lowered, and surface tension forces drive surface flattening. To investigate sorption kinetics and surface-smoothing phenomena, a series of vapor-deposited poly(amic acid) films were exposed to dimethyl sulfoxide vapors. During solvent exposure, the surface topology was continuously monitored using light interference microscopy. The resulting power spectra indicate that high-frequency defects smooth faster than low-frequency defects. This frequency dependence was studied by depositing polymer films onto a series of 2D sinusoidal surfaces and performing smoothing experiments. Results show that the amplitudes of the sinusoidal surfaces decay exponentially with solvent exposure time, and the exponential decay constants are proportional to surface frequency. This work was performed under the auspices of the U.S. Department of Energy by the University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Comparative Kinetic Study and Microwaves Non-Thermal Effects on the Formation of Poly(amic acid) 4,4′-(Hexafluoroisopropylidene)diphthalic Anhydride (6FDA) and 4,4′-(Hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (BAPHF). Reaction Activated by Microwave, Ultrasound and Conventional Heating

PubMed Central

Tellez, Hugo Mendoza; Alquisira, Joaquín Palacios; Alonso, Carlos Rius; Cortés, José Guadalupe López; Toledano, Cecilio Alvarez

2011-01-01

Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system. PMID:22072913

Comparative kinetic study and microwaves non-thermal effects on the formation of poly(amic acid) 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 4,4'-(hexafluoroisopropylidene)bis(p-phenyleneoxy)dianiline (BAPHF). Reaction activated by microwave, ultrasound and conventional heating.

PubMed

Tellez, Hugo Mendoza; Alquisira, Joaquín Palacios; Alonso, Carlos Rius; Cortés, José Guadalupe López; Toledano, Cecilio Alvarez

2011-01-01

Green chemistry is the design of chemical processes that reduce or eliminate negative environmental impacts. The use and production of chemicals involve the reduction of waste products, non-toxic components, and improved efficiency. Green chemistry applies innovative scientific solutions in the use of new reagents, catalysts and non-classical modes of activation such as ultrasounds or microwaves. Kinetic behavior and non-thermal effect of poly(amic acid) synthesized from (6FDA) dianhydride and (BAPHF) diamine in a low microwave absorbing p-dioxane solvent at low temperature of 30, 50, 70 °C were studied, under conventional heating (CH), microwave (MW) and ultrasound irradiation (US). Results show that the polycondensation rate decreases (MW > US > CH) and that the increased rates observed with US and MW are due to decreased activation energies of the Arrhenius equation. Rate constant for a chemical process activated by conventional heating declines proportionally as the induction time increases, however, this behavior is not observed under microwave and ultrasound activation. We can say that in addition to the thermal microwave effect, a non-thermal microwave effect is present in the system.

Poly(Amide-imide) Aerogel Materials Produced via an Ice Templating Process

PubMed Central

Gawryla, Matthew D.; Arndt, Eric M.

2018-01-01

Low density composites of sodium montmorillonite and poly(amide-imide) polymers have been created using an ice templating method, which serves as an alternative to the often-difficult foaming of high temperature/high performance polymers. The starting polymer was received in the poly(amic acid) form which can be cured using heat, into a water insoluble amide-imide copolymer. The resulting materials have densities in the 0.05 g/cm3 range and have excellent mechanical properties. Using a tertiary amine as a processing aid provides for lower viscosity and allows more concentrated polymer solutions to be used. The concentration of the amine relative to the acid groups on the polymer backbone has been found to cause significant difference in the mechanical properties of the dried materials. The synthesis and characterization of low density versions of two poly(amide-imide) polymers and their composites with sodium montmorillonite clay are discussed in the present work. PMID:29401663

Poly(Amide-imide) Aerogel Materials Produced via an Ice Templating Process.

PubMed

Gawryla, Matthew D; Arndt, Eric M; Sánchez-Soto, Miguel; Schiraldi, David A

2018-02-03

Low density composites of sodium montmorillonite and poly(amide-imide) polymers have been created using an ice templating method, which serves as an alternative to the often-difficult foaming of high temperature/high performance polymers. The starting polymer was received in the poly(amic acid) form which can be cured using heat, into a water insoluble amide-imide copolymer. The resulting materials have densities in the 0.05 g/cm³ range and have excellent mechanical properties. Using a tertiary amine as a processing aid provides for lower viscosity and allows more concentrated polymer solutions to be used. The concentration of the amine relative to the acid groups on the polymer backbone has been found to cause significant difference in the mechanical properties of the dried materials. The synthesis and characterization of low density versions of two poly(amide-imide) polymers and their composites with sodium montmorillonite clay are discussed in the present work.

Branched Rod-Coil Polyimide-Poly(Alkylene Oxide) Copolymers and Electrolyte Compositions

NASA Technical Reports Server (NTRS)

Meador, Maryann B. (Inventor); Tigelaar, Dean M. (Inventor)

2014-01-01

Crosslinked polyimide-poly(alkylene oxide) copolymers capable of holding large volumes of liquid while maintaining good dimensional stability. Copolymers are derived at ambient temperatures from amine endcapped amic-acid oligomers subsequently imidized in solution at increased temperatures, followed by reaction with trifunctional compounds in the presence of various additives. Films of these copolymers hold over four times their weight at room temperature of liquids such as ionic liquids (RTIL) and/or carbonate solvents. These rod-coil polyimide copolymers are used to prepare polymeric electrolytes by adding to the copolymers various amounts of compounds such as ionic liquids (RTIL), lithium trifluoromethane-sulfonimide (LiTFSi) or other lithium salts, and alumina.

Amidase Activity of AmiC Controls Cell Separation and Stem Peptide Release and Is Enhanced by NlpD in Neisseria gonorrhoeae.

PubMed

Lenz, Jonathan D; Stohl, Elizabeth A; Robertson, Rosanna M; Hackett, Kathleen T; Fisher, Kathryn; Xiong, Kalia; Lee, Mijoon; Hesek, Dusan; Mobashery, Shahriar; Seifert, H Steven; Davies, Christopher; Dillard, Joseph P

2016-05-13

The human-restricted pathogen Neisseria gonorrhoeae encodes a single N-acetylmuramyl-l-alanine amidase involved in cell separation (AmiC), as compared with three largely redundant cell separation amidases found in Escherichia coli (AmiA, AmiB, and AmiC). Deletion of amiC from N. gonorrhoeae results in severely impaired cell separation and altered peptidoglycan (PG) fragment release, but little else is known about how AmiC functions in gonococci. Here, we demonstrated that gonococcal AmiC can act on macromolecular PG to liberate cross-linked and non-cross-linked peptides indicative of amidase activity, and we provided the first evidence that a cell separation amidase can utilize a small synthetic PG fragment as substrate (GlcNAc-MurNAc(pentapeptide)-GlcNAc-MurNAc(pentapeptide)). An investigation of two residues in the active site of AmiC revealed that Glu-229 is critical for both normal cell separation and the release of PG fragments by gonococci during growth. In contrast, Gln-316 has an autoinhibitory role, and its mutation to lysine resulted in an AmiC with increased enzymatic activity on macromolecular PG and on the synthetic PG derivative. Curiously, the same Q316K mutation that increased AmiC activity also resulted in cell separation and PG fragment release defects, indicating that activation state is not the only factor determining normal AmiC activity. In addition to displaying high basal activity on PG, gonococcal AmiC can utilize metal ions other than the zinc cofactor typically used by cell separation amidases, potentially protecting its ability to function in zinc-limiting environments. Thus gonococcal AmiC has distinct differences from related enzymes, and these studies revealed parameters for how AmiC functions in cell separation and PG fragment release. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Role of Two Cell Wall Amidases in Septal Junction and Nanopore Formation in the Multicellular Cyanobacterium Anabaena sp. PCC 7120

PubMed Central

Bornikoel, Jan; Carrión, Alejandro; Fan, Qing; Flores, Enrique; Forchhammer, Karl; Mariscal, Vicente; Mullineaux, Conrad W.; Perez, Rebeca; Silber, Nadine; Wolk, C. Peter; Maldener, Iris

2017-01-01

Filamentous cyanobacteria have developed a strategy to perform incompatible processes in one filament by differentiating specialized cell types, N2-fixing heterocysts and CO2-fixing, photosynthetic, vegetative cells. These bacteria can be considered true multicellular organisms with cells exchanging metabolites and signaling molecules via septal junctions, involving the SepJ and FraCD proteins. Previously, it was shown that the cell wall lytic N-acetylmuramyl-L-alanine amidase, AmiC2, is essential for cell–cell communication in Nostoc punctiforme. This enzyme perforates the septal peptidoglycan creating an array of nanopores, which may be the framework for septal junction complexes. In Anabaena sp. PCC 7120, two homologs of AmiC2, encoded by amiC1 and amiC2, were identified and investigated in two different studies. Here, we compare the function of both AmiC proteins by characterizing different Anabaena amiC mutants, which was not possible in N. punctiforme, because there the amiC1 gene could not be inactivated. This study shows the different impact of each protein on nanopore array formation, the process of cell–cell communication, septal protein localization, and heterocyst differentiation. Inactivation of either amidase resulted in significant reduction in nanopore count and in the rate of fluorescent tracer exchange between neighboring cells measured by FRAP analysis. In an amiC1 amiC2 double mutant, filament morphology was affected and heterocyst differentiation was abolished. Furthermore, the inactivation of amiC1 influenced SepJ localization and prevented the filament-fragmentation phenotype that is characteristic of sepJ or fraC fraD mutants. Our findings suggest that both amidases are to some extent redundant in their function, and describe a functional relationship of AmiC1 and septal proteins SepJ and FraCD. PMID:28929086

Role of Two Cell Wall Amidases in Septal Junction and Nanopore Formation in the Multicellular Cyanobacterium Anabaena sp. PCC 7120.

PubMed

Bornikoel, Jan; Carrión, Alejandro; Fan, Qing; Flores, Enrique; Forchhammer, Karl; Mariscal, Vicente; Mullineaux, Conrad W; Perez, Rebeca; Silber, Nadine; Wolk, C Peter; Maldener, Iris

2017-01-01

Filamentous cyanobacteria have developed a strategy to perform incompatible processes in one filament by differentiating specialized cell types, N 2 -fixing heterocysts and CO 2 -fixing, photosynthetic, vegetative cells. These bacteria can be considered true multicellular organisms with cells exchanging metabolites and signaling molecules via septal junctions, involving the SepJ and FraCD proteins. Previously, it was shown that the cell wall lytic N -acetylmuramyl-L-alanine amidase, AmiC2, is essential for cell-cell communication in Nostoc punctiforme . This enzyme perforates the septal peptidoglycan creating an array of nanopores, which may be the framework for septal junction complexes. In Anabaena sp. PCC 7120, two homologs of AmiC2, encoded by amiC1 and amiC2 , were identified and investigated in two different studies. Here, we compare the function of both AmiC proteins by characterizing different Anabaena amiC mutants, which was not possible in N. punctiforme , because there the amiC1 gene could not be inactivated. This study shows the different impact of each protein on nanopore array formation, the process of cell-cell communication, septal protein localization, and heterocyst differentiation. Inactivation of either amidase resulted in significant reduction in nanopore count and in the rate of fluorescent tracer exchange between neighboring cells measured by FRAP analysis. In an amiC1 amiC2 double mutant, filament morphology was affected and heterocyst differentiation was abolished. Furthermore, the inactivation of amiC1 influenced SepJ localization and prevented the filament-fragmentation phenotype that is characteristic of sepJ or fraC fraD mutants. Our findings suggest that both amidases are to some extent redundant in their function, and describe a functional relationship of AmiC1 and septal proteins SepJ and FraCD.

High aspect ratio patterning of photosensitive polyimide with low thermal expansion coefficient and low dielectric constant

NASA Astrophysics Data System (ADS)

Dick, Andrew R.; Bell, William K.; Luke, Brendan; Maines, Erin; Mueller, Brennen; Rawlings, Brandon; Kohl, Paul A.; Grant Willson, C.

2016-07-01

A photosensitive polyimide system based on amine catalyzed imidization of a precursor poly(amic ester) is described. The material is based on the meta ethyl ester of pyromellitic dianhydride and 2,2' bis(trifluoromethyl)benzidine. It acts as a negative tone resist when formulated with a photobase generator. The material exhibits a dielectric constant of 3.0 in the gigahertz range, a coefficient of thermal expansion of 6±2 ppm/K, and can be patterned to aspect ratios of >2 when formulated with a highly quantum efficient cinnamide type photobase generator.

Production of polyimide ceria nanocomposites by development of molecular hook technology in nano-sonochemistry.

PubMed

Hatami, Mehdi

2018-06-01

Poly(amic acid), the precursor of polyimide (PI), was used for the preparation of PI/CeO 2 nanocomposites (NC)s by ultrasonic assisted technique via insertion of the surface modified CeO 2 nanoparticles (NP)s into PI matrix. In the preparation stages, in the first, the modifications of CeO 2 NPs by using hexadecyltrimethoxysilane (HDTMS) as a binder were targeted using ultrasonic waves. In the second step, newly designed PI structure was formed from the sonochemical imidization process as a molecular hook. In this step two different reactions were occurred. The acetic acid elimination reaction in the main chain of macromolecule, and the acetylation reaction in the side chains of poly(amic acid) were accomplished. By acetylation process the hook structure was created for trapping of the modified nanoparticles. In the final step the preparation of PI NCs were achieved by sonochemical process. The structural and thermal properties of pure PI and PI/CeO 2 NCs were studied by several techniques such as fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy (NMR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and thermal analyses. FT-IR and 1 H NMR spectra confirmed the success in preparation of PI matrix. The FE-SEM, TEM, and AFM analyses showed the uniform distribution of CeO 2 NPs in PI matrix. The XRD patterns of NCs show the presence of crystalline CeO 2 NPs in amorphous PI matrix. The thermal analysis results reveal that, with increases in the content of CeO 2 NPs in PI matrix, the thermally stability factors of samples were improved. Copyright © 2018 Elsevier B.V. All rights reserved.

AMIC Cartilage Repair in a Professional Soccer Player

PubMed Central

Bark, S.; Riepenhof, H.; Gille, J.

2012-01-01

We report a case of a professional soccer player suffering from a traumatic cartilage lesion grade IV according to the Outerbridge classification at the femoral condyle treated with an enhanced microfracture technique (AMIC). Autologous Matrix-Induced Chondrogenesis (AMIC) is an innovative treatment for localized full-thickness cartilage defects combining the well-known microfracturing with collagen scaffold and fibrin glue. Because of the cartilage lesion (3 cm2), an AMIC procedure was performed followed by a rehabilitation program according to the protocols in the literature, (Steadman et al.; 2003). After 8 months of rehabilitation, the player returned to team training and after 10 months to competition. Altogether he returned to the same skill level for almost one year after the index operation. He is very satisfied with the clinical results after AMIC, which corresponds with the Lysholm score of 90 points at 12 months. PMID:23259120

Management Information System

NASA Technical Reports Server (NTRS)

1984-01-01

New Automated Management Information Center (AMIC) employs innovative microcomputer techniques to create color charts, viewgraphs, or other data displays in a fraction of the time formerly required. Developed under Kennedy Space Center's contract by Boeing Services International Inc., Seattle, WA, AMIC can produce an entirely new informational chart in 30 minutes, or an updated chart in only five minutes. AMIC also has considerable potential as a management system for business firms.

Polyimide amic acid salts and polyimide membranes formed therefrom

DOEpatents

Ding, Yong; Bikson, Benjamin; Nelson, Joyce Katz; Macheras, James Timothy

2004-04-06

The invention relates to preparation and uses of novel polymeric materials, polyimide amic acid salts (PIAAS). The use of these materials for the fabrication of fluid separation membranes is further disclosed.

Altered insular activation and increased insular functional connectivity during sad and happy face processing in adolescent major depressive disorder.

PubMed

Henje Blom, Eva; Connolly, Colm G; Ho, Tiffany C; LeWinn, Kaja Z; Mobayed, Nisreen; Han, Laura; Paulus, Martin P; Wu, Jing; Simmons, Alan N; Yang, Tony T

2015-06-01

Major depressive disorder (MDD) is a leading cause of disability worldwide and occurs commonly first during adolescence. The insular cortex (IC) plays an important role in integrating emotion processing with interoception and has been implicated recently in the pathophysiology of adult and adolescent MDD. However, no studies have yet specifically examined the IC in adolescent MDD during processing of faces in the sad-happy continuum. Thus, the aim of the present study is to investigate the IC during sad and happy face processing in adolescents with MDD compared to healthy controls (HCL). Thirty-one adolescents (22 female) with MDD and 36 (23 female) HCL underwent a well-validated emotional processing fMRI paradigm that included sad and happy face stimuli. The MDD group showed significantly less differential activation of the anterior/middle insular cortex (AMIC) in response to sad versus happy faces compared to the HCL group. AMIC also showed greater functional connectivity with right fusiform gyrus, left middle frontal gyrus, and right amygdala/parahippocampal gyrus in the MDD compared to HCL group. Moreover, differential activation to sad and happy faces in AMIC correlated negatively with depression severity within the MDD group. Small age-range and cross-sectional nature precluded assessment of development of the AMIC in adolescent depression. Given the role of the IC in integrating bodily stimuli with conscious cognitive and emotional processes, our findings of aberrant AMIC function in adolescent MDD provide a neuroscientific rationale for targeting the AMIC in the development of new treatment modalities. Copyright © 2015 Elsevier B.V. All rights reserved.

AMICAL: An aid for architectural synthesis and exploration of control circuits

NASA Astrophysics Data System (ADS)

Park, Inhag

AMICAL is an architectural synthesis system for control flow dominated circuits. A behavioral finite state machine specification, where the scheduling and register allocation were performed, is presented. An abstract architecture specification that may feed existing silicon compilers acting at the logic and register transfer levels is described. AMICAL consists of five main functions allowing automatic, interactive and manual synthesis, as well as the combination of these methods. These functions are a synthesizer, a graphics editor, a verifier, an evaluator, and a documentor. Automatic synthesis is achieved by algorithms that allocate both functional units, stored in an expandable user defined library, and connections. AMICAL also allows the designer to interrupt the synthesis process at any stage and make interactive modifications via a specially designed graphics editor. The user's modifications are verified and evaluated to ensure that no design rules are broken and that any imposed constraints are still met. A documentor provides the designer with status and feedback reports from the synthesis process.

High-performance supercapacitors based on hollow polyaniline nanofibers by electrospinning.

PubMed

Miao, Yue-E; Fan, Wei; Chen, Dan; Liu, Tianxi

2013-05-22

Hollow polyaniline (PANI) nanofibers with controllable wall thickness are fabricated by in situ polymerization of aniline using the electrospun poly(amic acid) fiber membrane as a template. A maximum specific capacitance of 601 F g(-1) has been achieved at 1 A g(-1), suggesting the potential application of hollow PANI nanofibers for supercapacitors. The superior electrochemical performance of the hollow nanofibers is attributed to their hollow structure, thin wall thickness, and orderly pore passages, which can drastically facilitate the ion diffusion and improve the utilization of the electroactive PANI during the charge-discharge processes. Furthermore, the high flexibility of the self-standing fiber membrane template provides possibilities for the facile construction and fabrication of conducting polymers with hollow nanostructures, which may find potential applications in various high-performance electrochemical devices.

Poly(dopamine) coating to biodegradable polymers for bone tissue engineering.

PubMed

Tsai, Wei-Bor; Chen, Wen-Tung; Chien, Hsiu-Wen; Kuo, Wei-Hsuan; Wang, Meng-Jiy

2014-02-01

In this study, a technique based on poly(dopamine) deposition to promote cell adhesion was investigated for the application in bone tissue engineering. The adhesion and proliferation of rat osteoblasts were evaluated on poly(dopamine)-coated biodegradable polymer films, such as polycaprolactone, poly(l-lactide) and poly(lactic-co-glycolic acid), which are commonly used biodegradable polymers in tissue engineering. Cell adhesion was significantly increased to a plateau by merely 15 s of dopamine incubation, 2.2-4.0-folds of increase compared to the corresponding untreated substrates. Cell proliferation was also greatly enhanced by poly(dopamine) deposition, indicated by shortened cell doubling time. Mineralization was also increased on the poly(dopamine)-deposited surfaces. The potential of poly(dopamine) deposition in bone tissue engineering is demonstrated in this study.

Isomeric oxydiphthalic anhydride polyimides

NASA Technical Reports Server (NTRS)

Gerber, Margaret K.; Pratt, J. Richard; Stclair, Terry L.

1988-01-01

Much of the polyimide research at Langley Research Center has focused on isomeric modification of the diamine component; polyimides having considerably improved processability and adhesion have resulted. The present structure-property study was designed to investigate how isomeric attachment of the three oxydiphthalic anhydride (ODPA) polyimides affects their properties. Each dianhydride, 3,4,3',4'-oxydiphthalic anhydride (4,4'-OPDA,I), 2,3,2',3'-oxydiphthalic anhydride (3,3'-ODPA,II), and 2,3,3',4'-oxydiphthalic anhydride (3,4'-OPDA,III), was reacted with p-phenylenediamine, 4,4'-oxydianiline, 3,3'-diaminodiphenylsulfone, 3,3'-diaminobenzophenone, and 4,4'-bis(3-aminophenoxy)benzophenone in DMAc. The inherent viscosities of the resulting poly(amic acids) were determined. Thermally imidized films were studied for their creasability and solubility, as well as by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and wide angle X-ray scattering (WAXS). A comparison of these properties will be made.

Phenylethynyl Phthalic Anhydride

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

1997-01-01

Controlled molecular weight PhenylEthynyl Terminated Imide oligomers (PETIs) have been prepared by the cyclodehydration of precursor phenylethynyl terminated amic acid oligomers. Amino terminated amic acid oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and subsequently endcapped with PhenylEthynyl Phthalic Anhydride(s) (PEPA). The polymerizations are carried out in polar aprotic solvents such as N-methyl-2pyrrolidinone or N N-dimethylacetamide under nitrogen at room temperature. The amic acid oligomers are subsequently cyclodehydrated either thermally or chemically to the corresponding imide oligomers. Direct preparation of PETIs from the reaction of dianhydride(s) with an excess of diamine(s) and endcapped with phenylethynyl phthalic anhydride(s) has been performed in m-cresol. Phenylethynyl phthalic anhydrides are synthesized by the palladium catalyzed reaction of phenylacetylene with bromo substituted phthalic anhydrides in triethylamine. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

Imide Oligomers Endcapped with Phenylethynl Phthalic Anhydrides and Polymers Therefrom

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Smith, Joseph G., Jr. (Inventor)

1998-01-01

Controlled molecular weight phenylethynyl terminated imide oligomers (PETIs) have been prepared by the cyclodehydration of precursor phenylethynyl terminated amic acid oligomers. Amino terminated amic acid oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and subsequently endcapped with phenylethynyl phthalic anhydride(s) (PEPA). The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N.N-dimethylacetamide under nitrogen at room temperature. The amic acid oligomers are subsequently cyclodehydrated either thermally or cheznicauy to the corresponding imide oligomers. Direct preparation of PETIs from the reaction of dianhydxide(s) with an excess of diamine(s) and endcapped with phenylethynyl phthalic anhydride(s) has been performed in m-cresol. Phenylethynyl phthalic anhydrides are synthesized by the palladium catalyzed reaction of phenylacetylene with bromo substituted phthalic anhydrides in triethylamine. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

Imide oligomers endcapped with phenylethynyl phthalic anhydrides and polymers therefrom

NASA Technical Reports Server (NTRS)

Hergenrother, Paul M. (Inventor); Smith, Jr., Joseph G. (Inventor)

1996-01-01

Controlled molecular weight phenylethynyl terminated imide oligomers (PETIs) have been prepared by the cyclodehydration of precursor phenylethynyl terminated amic acid oligomers. Amino terminated amic acid oligomers are prepared from the reaction of dianhydride(s) with an excess of diamine(s) and subsequently endcapped with phenylethynyl phthalic anhydride(s) (PEPA). The polymerizations are carried out in polar aprotic solvents such as N-methyl-2-pyrrolidinone or N,N-dimethylacetamide under nitrogen at room temperature. The amic acid oligomers are subsequently cyclodehydrated either thermally or chemically to the corresponding imide oligomers. Direct preparation of PETIs from the reaction of dianhydride(s) with an excess of diamine(s) and endcapped with phenylethynyl phthalic anhydride(s) has been performed in m-cresol. Phenylethynyl phthalic anhydrides are synthesized by the palladium catalyzed reaction of phenylacetylene with bromo substituted phthalic anhydrides in triethylamine. These new materials exhibit excellent properties and are potentially useful as adhesives, coatings, films, moldings and composite matrices.

Surface Polarity and Self-Structured Nanogrooves Collaboratively Oriented Molecular Packing for High Crystallinity toward Efficient Charge Transport.

PubMed

Ji, Deyang; Xu, Xiaomin; Jiang, Longfeng; Amirjalayer, Saeed; Jiang, Lang; Zhen, Yonggang; Zou, Ye; Yao, Yifan; Dong, Huanli; Yu, Junsheng; Fuchs, Harald; Hu, Wenping

2017-02-22

Efficient charge transport in organic semiconductors is essential for construction of high performance optoelectronic devices. Herein, for the first time, we demonstrate that poly(amic acid) (PAA), a facilely deposited and annealing-free dielectric layer, can tailor the growth of organic semiconductor films with large area and high crystallinity toward efficient charge transport and high mobility in their thin film transistors. Pentacene is used as a model system to demonstrate the concept with mobility up to 30.6 cm 2 V -1 s -1 , comparable to its high quality single crystal devices. The structure of PAA has corrugations with OH groups pointing out of the surface, and the presence of an amide bond further allows adjacent polymer strands to interact via hydrogen bonding, leading to a self-rippled surface perpendicular to the corrugation. On the other hand, the strong polar groups (-COOH/-CONH) of PAA could provide repulsive forces between PAA and pentacene, which results in the vertical orientation of pentacene on the dielectric surface. Indeed, in comparison with its imidized counterpart polyimide (PI), PAA dielectric significantly enhances the film crystallinity, drastically increases the domain size, and decreases the interface trap density, giving rise to superior device performance with high mobility. This concept can be extended to more organic semiconducting systems, e.g., 2,6-diphenylanthracene (DPA), tetracene, copper phthalocyanine (CuPc), and copper hexadecafluorophthalocyanine (F 16 CuPc), demonstrating the general applicability. The results show the importance of combining surface nanogrooves with the strong polarity in orienting the molecular arrangement for high crystallinity toward efficient charge transport in organic semiconductors.

Response to social challenge in young bonnet (Macaca radiata) and pigtail (Macaca nemestrina) macaques is related to early maternal experiences.

PubMed

Weaver, Ann; Richardson, Rebecca; Worlein, Julie; De Waal, Frans; Laudenslager, Mark

2004-04-01

Previous experience affects how young primates respond to challenging social situations. The present retrospective study looked at one aspect of early experience, the quality of the mother-infant relationship, to determine its relationship to young bonnet and pigtail macaques' responses to two social challenges: temporary maternal separation at 5-6 months and permanent transfer to an unfamiliar peer group at 16-17 months. Relationship quality was measured quantitatively on 30 macaque mother-infant pairs with the Relationship Quality Index (RQI), the ratio of relative affiliation to relative agonism as previously applied to capuchin monkeys. Infants with high RQI values had amicable mother-infant relationships and infants with low RQI values had agonistic mother-infant relationships. Young monkeys with amicable and agonistic relationships showed consistent differences in behavior before, during, and after each social challenge, supporting the hypothesis that juveniles from amicable mother-infant relationships based on the RQI coped more effectively with social challenges than did juveniles from agonistic mother-infant relationships. Results suggest 1) characteristic amicability or agonism in early mother-offspring macaque relationships has the potential to influence offspring behavior in tense social contexts and 2) the RQI is useful as one of a coordinated suite of methods for studying the development of social skills. Copyright 2004 Wiley-Liss, Inc.

Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS).

PubMed

Kretzschmar, M; Bieri, O; Miska, M; Wiewiorski, M; Hainc, N; Valderrabano, V; Studler, U

2015-04-01

The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm(2)/ms) was significantly higher compared to normal cartilage (1.46 μm(2)/ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. • MRI is used to assess morphology of the repair tissue during follow-up. • Quantitative MRI allows an estimation of biochemical properties of the repair tissue. • Differences between repair tissue and cartilage were more significant with dwDESS than T2 mapping.

RECOGNITION OF PYRENE USING MOLECULARLY-IMPRINTED ELECTROCHEMICALLY-DEPOSITED POLY (2-MERCAPTOBENZIMIDAZOLE) OR POLY(RESORCINOL) ON GOLD ELECTRODES

EPA Science Inventory

The feasibility of using thiol chemistry to form molecularly imprinted polymer-coated gold electrodes to measure pyrene is reported. For the first approach, poly(2-mercaptoimidazole) (2-MBI) was electrochemically deposited on gold electrodes in the presence or absence of the tem...

Hydroxyapatite/poly(epsilon-caprolactone) double coating on magnesium for enhanced corrosion resistance and coating flexibility.

PubMed

Jo, Ji-Hoon; Li, Yuanlong; Kim, Sae-Mi; Kim, Hyoun-Ee; Koh, Young-Hag

2013-11-01

Hydroxyapatite was deposited on pure magnesium (Mg) with a flexible poly(ε-caprolactone) interlayer to reduce the corrosion rate of Mg and enhance coating flexibility. The poly(ε-caprolactone) interlayer was uniformly coated on Mg by a spraying method, followed by hydroxyapatite deposition on the poly(ε-caprolactone) using an aerosol deposition method. In scanning electron microscopy observations, inorganic/organic composite-like structure was observed between the hydroxyapatite and poly(ε-caprolactone) layers, resulting from the collisions of hydroxyapatite particles into the poly(ε-caprolactone) matrix at the initial stage of the aerosol deposition. The corrosion resistance of the coated Mg was examined using potentiodynamic polarization tests. The hydroxyapatite/poly(ε-caprolactone) double coating remarkably improved the corrosion resistance of Mg in Hank's solution. In the in vitro cell tests, the coated Mg showed better cell adhesion compared with the bare Mg due to the reduced corrosion rate and enhanced biocompatibility. The stability and flexibility of hydroxyapatite/poly(ε-caprolactone) double coating was investigated by scanning electron microscopy inspections after the coated Mg was deformed. The hydroxyapatite coating on the poly(ε-caprolactone) interlayer revealed enhanced coating stability and flexibility without cracking or delamination during bending and stretching compared with the hydroxyapatite single coating. These results demonstrated that the hydroxyapatite/poly(ε-caprolactone) double coating significantly improved the surface corrosion resistance of Mg and enhanced coating flexibility for use of Mg as a biodegradable implant.

Colorless polyimide/organoclay nanocomposite substrates for flexible organic light-emitting devices.

PubMed

Kim, Jin-Hoe; Choi, Myeon-Chon; Kim, Hwajeong; Kim, Youngkyoo; Chang, Jin-Hae; Han, Mijeong; Kim, Il; Ha, Chang-Sik

2010-01-01

We report the preparation and application of indium tin oxide (ITO) coated fluorine-containing polyimide/organoclay nanocomposite substrate. Fluorine-containing polyimide/organoclay nanocomposite films were prepared through thermal imidization of poly(amic acid)/organoclay mixture films, whilst on which ITO thin films were coated on the films using a radio-frequency planar magnetron sputtering by varying the substrate temperature and the ITO thickness. Finally the ITO coated fluorine-containing polyimide/organoclay nanocomposite substrate was employed to make flexible organic light-emitting devices (OLED). Results showed that the lower sheet resistance was achieved when the substrate temperature was high and the ITO film was thick even though the optical transmittance was slightly lowered as the thickness increased. approximately 10 nm width ITO nanorods were found for all samples but the size of clusters with the nanorods was generally increased with the substrate temperature and the thickness. The flexible OLED made using the present substrate was quite stable even when the device was extremely bended.

Transparent anti-stain coatings with good thermal and mechanical properties based on polyimide-silica nanohybrids.

PubMed

Choi, Myeon-Cheon; Sung, Giju; Nagappan, Saravanan; Han, Mi-Jeong; Ha, Chang-Sik

2012-07-01

In this work, we synthesized polyimide/silica hybrid materials via sol-gel method using a fluorinated poly(amic acid) silane precursor and a variety of perfluorosilane contents. We studied the influence of a hybrid coating film with the following characteristics; hydrophobicity, oleophobicity, optical transparency, and surface hardness of the coating films. The hybrid coatings with the fluorosilane contents up to 10 wt% are optically transparent and present good thermal stability with a degradation temperature of > 500 degrees C as well as a glass transition of > 300 degrees C. Both water contact angle and oil contact angle increase rapidly with introducing small amount of the fluorosilane in the hybrids and reaches the maximum of 115 degrees and 61 degrees, respectively. The hardness of the hybrid coatings increases up to 5H with an increase of the FTES content in the hybrids. These colorless, transparent, and thermally stable hybrid materials could be suitable for applications as anti-stain coatings.

Reduction in the formation temperature of Poly-SiGe alloy thin film in Si/Ge system

NASA Astrophysics Data System (ADS)

Tah, Twisha; Singh, Ch. Kishan; Madapu, K. K.; Sarguna, R. M.; Magudapathy, P.; Ilango, S.

2018-04-01

The role of deposition temperature in the formation of poly-SiGe alloy thin film in Si/Ge system is reported. For the set ofsamples deposited without any intentional heating, initiation of alloying starts upon post annealingat ˜ 500 °C leading to the formation of a-SiGe. Subsequently, poly-SiGe alloy phase could formonly at temperature ≥ 800 °C. Whereas, for the set of samples deposited at 500 °C, in-situ formation of poly-SiGe alloy thin film could be observed. The energetics of the incoming evaporated atoms and theirsubsequent diffusionsin the presence of the supplied thermal energy is discussed to understand possible reasons for lowering of formation temperature/energyof the poly-SiGe phase.

Impella 2.5 initiated prior to unprotected left main PCI in acute myocardial infarction complicated by cardiogenic shock improves early survival.

PubMed

Meraj, Perwaiz M; Doshi, Rajkumar; Schreiber, Theodore; Maini, Brijeshwar; O'Neill, William W

2017-06-01

To assess post-procedural outcomes when Impella 2.5 percutaneous left ventricular assist device (pLVAD) support is initiated either prior to or after percutaneous coronary intervention (PCI) on unprotected left main coronary artery (ULMCA) culprit lesion in the context of acute myocardial infarction cardiogenic shock (AMICS). Initiation of Impella 2.5 pLVAD prior to PCI is associated with significant survival benefit in the setting of AMICS. Outcomes of those presenting with a ULMCA culprit lesion in this setting have not been well characterized. Thirty-six consecutive patients in the cVAD Registry supported with Impella 2.5 pLVAD for AMICS who underwent PCI on ULMCA culprit lesion were included in our multicenter study. The average age was 69.8 ± 14.2 years, 77.8% were male, 72.7% were in CS at admission, 44.4% sustained one or multiple cardiac arrests, and 30.6% had anoxic brain injury. Baseline characteristics were comparable between the Pre-PCI group (n = 20) and Post-PCI group (n = 16). Non-ST segment elevation myocardial infarction and greater coronary disease burden were significantly more frequent in the Pre-PCI group but they had significantly better survival to discharge (55.0% vs 18.8%, P = 0.041). Kaplan-Meier 30-day survival analysis showed very poor survival in Post-PCI group (48.1% vs 12.5%, Log-Rank P = 0.004). Initiation of Impella 2.5 pLVAD prior to as compared with after PCI of ULMCA for AMICS culprit lesion is associated with significant early survival. As previously described, patients supported after PCI appear to have very poor survival at 30 days. © 2017, Wiley Periodicals, Inc.

Deposition and characterization of silicon thin-films by aluminum-induced crystallization

NASA Astrophysics Data System (ADS)

Ebil, Ozgenc

Polycrystalline silicon (poly-Si) as a thin-film solar cell material could have major advantages compared to non-silicon thin-film technologies. In theory, thin-film poly-Si may retain the performance and stability of c-Si while taking advantage of established manufacturing techniques. However, poly-Si films deposited onto foreign substrates at low temperatures typically have an average grain size of 10--50 nm. Such a grain structure presents a potential problem for device performance since it introduces an excessive number of grain boundaries which, if left unpassivated, lead to poor solar cell properties. Therefore, for optimum device performance, the grain size of the poly-Si film should be at least comparable to the thickness of the films. For this project, the objectives were the deposition of poly-Si thin-films with 2--5 mum grain size on glass substrates using in-situ and conventional aluminum-induced crystallization (AIC) and the development of a model for AIC process. In-situ AIC experiments were performed using Hot-Wire Chemical Vapor Deposition (HWCVD) both above and below the eutectic temperature (577°C) of Si-Al binary system. Conventional AIC experiments were performed using a-Si layers deposited on aluminum coated glass substrates by Electron-beam deposition, Plasma Enhanced Chemical Vapor Deposition (PECVD) and HWCVD. Continuous poly-Si films with an average grain size of 10 mum on glass substrates were achieved by both in-situ and conventional aluminum-induced crystallization of Si below eutectic temperature. The grain size was determined by three factors; the grain structure of Al layer, the nature of the interfacial oxide, and crystallization temperature. The interface oxide was found to be crucial for AIC process but not necessary for crystallization itself. The characterization of interfacial oxide layer formed on Al films revealed a bilayer structure containing Al2O3 and Al(OH)3 . The effective activation energy for AIC process was determined to be 0.9 eV and depended on the nature of the interfacial oxide layer. Poly-Si layers prepared by AIC technique can be used as seed layers for epitaxial growth of bulk Si layer or as back contacts in c-Si based solar cells.

Process for preparing phthalocyanine polymer from imide containing bisphthalonitrile

NASA Technical Reports Server (NTRS)

Achar, Bappalige N. (Inventor); Fohlen, George M. (Inventor); Parker, John A. (Inventor)

1987-01-01

Imide-linked bisphthalonitrile compounds are prepared by combining a dicyano aromatic diamine and an organic dianhydride to produce an amic acid linked bisphthalonitrile compound. The amic acid linked bisphthalonitrile compound is dehydrocyclized to produce the imide-linked bisphthalonitrile compounds. The imide-linked bisphthalonitrile compounds may be polymerized to produce a phythalocyanine polymer by heating the imide-linked bisphthalonitrile compound, either alone or in the presence of a metal powder or a metal salt. These compounds are useful in the coating, laminating and molding arts. The polymers are useful in composite matrix resins where increased fire resistance, toughness and resistance to moisture are required, particularly as secondary structures in aircraft and spacecraft.

Use of collagen scaffold and autologous bone marrow concentrate as a one-step cartilage repair in the knee: histological results of second-look biopsies at 1 year follow-up.

PubMed

Gigante, A; Calcagno, S; Cecconi, S; Ramazzotti, D; Manzotti, S; Enea, D

2011-01-01

Chondral articular defects are a key concern in orthopaedic surgery. To overcome the disadvantages of autologous chondrocyte implantation (ACI) and to improve the outcomes of autologous matrix-induced chondrogenesis (AMIC), the latter technique is currently augmented with bone marrow concentrate injected under or seeded onto the scaffold. However, to date, only a little is known about histological outcomes of either the AMIC technique or AMIC associated with bone marrow concentrate. This study aimed to evaluate the quality of the repair tissue obtained from biopsies harvested during second-look arthroscopy after arthroscopic AMIC augmented with bone marrow concentrate. We analysed five second-look core biopsies harvested at 12 months follow-up. At the time of biopsy the surgeon reported the quality of the repair tissue using the standard ICRS Cartilage Repair Assessment (CRA). Every biopsy together with patient data was sent to our centre to undergo blind histological evaluation (ICRS II Visual Histological Assessment Scale) and data analysis. Five asymptomatic patients (mean age 43.4 years) had isolated lesions (mean size was 3.7 cm2) at the medial femoral condyle. All the implants appeared nearly normal (ICRS CRA) at arthroscopic evaluation and had a mean overall histological (ICRS II) of 59.8±14,5. Hyaline-like matrix was found in only one case, a mixture of hyaline/fibrocartilage was found in one case and fibrocartilage was found three cases. Our clinical and histological data suggest that this procedure achieved a nearly normal arthroscopic appearance and a satisfactory repair tissue, which was possibly still maturing at 12 months follow-up. Further studies are needed to understand the true potential of one-step procedures in the repair of focal chondral lesions in the knee.

Sports Activity After Reconstruction of Osteochondral Lesions of the Talus With Autologous Spongiosa Grafts and Autologous Matrix-Induced Chondrogenesis.

PubMed

Wiewiorski, Martin; Werner, Lorenzo; Paul, Jochen; Anderson, Andrew E; Barg, Alexej; Valderrabano, Victor

2016-10-01

For the treatment of osteochondral lesions of the talus (OCLTs), autologous matrix-induced chondrogenesis (AMIC) is a safe 1-step procedure with good clinical and radiological results. However, data regarding postoperative sports activity after AMIC are limited. To identify significant factors influencing the rate of postoperative sports and recreational activities. Case series; Level of evidence, 4. The sports and recreational activities of 60 patients (mean age, 34.9 ± 11.5 years) undergoing the AMIC procedure were retrospectively analyzed at a mean of 46.9 ± 17.8 months (range, 24.5-87.0 months) postoperatively. The visual analog scale (VAS) for pain score, Tegner activity scale score, activity rating scale (ARS) score, and satisfaction with surgery outcomes were assessed. Corrective calcaneal osteotomy was performed in 38 of 60 (63.3%) patients. Ligament repair was performed in 41 of 60 (68.3%) patients. The mean VAS score improved significantly from 6.9 ± 1.6 points (range, 5-10 points) preoperatively to 2.3 ± 1.9 points (range, 0-6 points) at latest follow-up (P < .001). No significant change in the mean Tegner activity scale score (3.3 ± 2.0 preoperatively to 3.4 ± 2.2 postoperatively; P = .526) and the mean ARS score (2.6 ± 4.3 preoperatively to 2.3 ± 3.4 postoperatively; P = .874) was noted. The percentage of patients involved in sports activity before the onset of symptoms became significantly lower at the time of surgery (from 95.0% to 53.3%; P < .001); no significant difference was noted postoperatively (from 53.3% to 58.3%; P = .663). No significant difference of the weekly sports frequency and the duration of sports activity was found postoperatively. Patients undergoing AMIC repair of an OCLT participate at a similar low postoperative sports and recreational activity level compared with the preoperative level. © 2016 The Author(s).

Structural properties of a-Si films and their effect on aluminum induced crystallization

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

Tankut, Aydin; Ozkol, Engin; Karaman, Mehmet

2015-10-15

In this paper, we report the influence of the structural properties of amorphous silicon (a-Si) on its subsequent crystallization behavior via the aluminum induced crystallization (AIC) method. Two distinct a-Si deposition techniques, electron beam evaporation and plasma enhanced chemical vapor deposition (PECVD), are compared for their effect on the overall AIC kinetics as well as the properties of the final poly-crystalline (poly-Si) silicon film. Raman and FTIR spectroscopy results indicate that the PECVD grown a-Si films has higher intermediate-range order, which is enhanced for increased hydrogen dilution during deposition. With increasing intermediate-range order of the a-Si, the rate of AICmore » is diminished, leading larger poly-Si grain size.« less

Anisotropic electrical conduction and reduction in dangling-bond density for polycrystalline Si films prepared by catalytic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Niikura, Chisato; Masuda, Atsushi; Matsumura, Hideki

1999-07-01

Polycrystalline Si (poly-Si) films with high crystalline fraction and low dangling-bond density were prepared by catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD. Directional anisotropy in electrical conduction, probably due to structural anisotropy, was observed for Cat-CVD poly-Si films. A novel method to separately characterize both crystalline and amorphous phases in poly-Si films using anisotropic electrical conduction was proposed. On the basis of results obtained by the proposed method and electron spin resonance measurements, reduction in dangling-bond density for Cat-CVD poly-Si films was achieved using the condition to make the quality of the included amorphous phase high. The properties of Cat-CVD poly-Si films are found to be promising in solar-cell applications.

Fabrication of composite films containing zirconia and cationic polyelectrolytes.

PubMed

Pang, Xin; Zhitomirsky, Igor

2004-03-30

Composite films were prepared by electrophoretic deposition of poly(ethylenimine) or poly(allylamine hydrochloride) combined with cathodic precipitation of zirconia. Films of up to several micrometers thick were obtained on Ni, Pt, stainless-steel, graphite, and carbon-felt substrates. When the concentration of polyelectrolytes in solutions and the deposition time were varied, the amount of the deposited material and its composition can be varied. The electrochemical intercalation of yttria-stabilized zirconia particles into the composite films has been demonstrated. Obtained results pave the way for the electrodeposition of other polymer-ceramic composites. The deposits were studied by thermogravimetric analysis, X-ray diffraction analysis, scanning electron microscopy, and atomic force microscopy. The mechanisms of deposition are discussed.

Investigating the chemical mist deposition technique for poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) on textured crystalline-silicon for organic/crystalline-silicon heterojunction solar cells

NASA Astrophysics Data System (ADS)

Hossain, Jaker; Ohki, Tatsuya; Ichikawa, Koki; Fujiyama, Kazuhiko; Ueno, Keiji; Fujii, Yasuhiko; Hanajiri, Tatsuro; Shirai, Hajime

2016-03-01

Chemical mist deposition (CMD) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was investigated in terms of cavitation frequency f, solvent, flow rate of nitrogen, substrate temperature Ts, and substrate dc bias Vs as variables for efficient PEDOT:PSS/crystalline silicon (c-Si) heterojunction solar cells. The high-speed-camera and differential mobility analysis characterizations revealed that the average size and flux of PEDOT:PSS mist depend on f, type of solvent, and Vs. Film deposition occurred when positive Vs was applied to the c-Si substrate at Ts of 30-40 °C, whereas no deposition of films occurred with negative Vs, implying that the film is deposited mainly from negatively charged mist. The uniform deposition of PEDOT:PSS films occurred on textured c-Si(100) substrates by adjusting Ts and Vs. The adhesion of CMD PEDOT:PSS film to c-Si was greatly enhanced by applying substrate dc bias Vs compared with that of spin-coated film. The CMD PEDOT:PSS/c-Si heterojunction solar cell devices on textured c-Si(100) in 2 × 2 cm2 exhibited a power conversion efficiency η of 11.0% with better uniformity of the solar cell parameters. Furthermore, η was increased to 12.5% by adding an AR coating layer of molybdenum oxide MoOx formed by CMD. These findings suggest that CMD with negatively charged mist has great potential for the uniform deposition of organic and inorganic materials on textured c-Si substrates by suitably adjusting Ts and Vs.

Transculturalization and validation of a Spanish translation of the specific lower limb osteoarthritis and quality of life questionnaire AMICAL: Arthrose des Membres Inférieurs et Qualité de vie AMIQUAL.

PubMed

Espinosa-Cuervo, Gisela; Guillermin, Francis; Rat, Anne-Christine; Duarte-Salazar, Carolina; Alemán-Hernández, Sylvia-I; Vergara-Álvarez, Yuriria; Goycochea-Robles, María-Victoria

2014-01-01

Several generic questionnaires have been used to measure quality of life in patients with Osteoarthritis (OA) since few instruments have been developed specifically for OA and none was developed for Spanish speaking patients. The purpose of the study was to validate and adapt to Spanish the French questionnaire AMICAL to measure quality of life in patients with hip and knee OA. Transversal, analytical study. The validation process was performed in phases: translation from French to Spanish, translated version analysis by a multidisciplinary expert team, application of a pilot test to patients to evaluate grammatical and content equivalence, blind back translation, and analysis. The questionnaire was applied to hip and knee OA patients, together with the SF-36 questionnaire, as well as the WOMAC and the Lequesne indexes. The reproducibility was evaluated applying the questionnaire after 72hours. The clinimetric analysis was calculated with SPSS 16.0. One hundred patients with hip OA and 100 patients with knee OA, radiological stages ii-iii, were included to evaluate homogeneity. Sixty-five patients with hip OA and 65 patients with knee OA were included to evaluate consistency. The final sample included 100 hip and 100 patients knee OA patients to estimate homogeneities and 65 patients were evaluated to estimate consistency. Mean (SD) age of patients with hip and knee OA, was 56.34 ± 13 and 60.1 ± 9.2, respectively. Sixty seven percent and 79.8% were female, respectively. Cronbach' alpha for AMICAL was 0.946 and 0.999, for hip OA and knee OA, respectively; and test-retest reliability using the intraclass correlation coefficients was 0.979 and 0.998, respectively. There was also a significant correlation with all the instruments (P<.05), except with the Lequesne index (r-0.383). The Spanish version of AMICAL questionnaire keep the clinimetric properties, homogeneity, and consistency, and has a good correlation with other instruments. Consequently, it is reliable, self-applicable, and includes domains beyond the functional capacity that better evaluate the quality of life. Copyright © 2013 Elsevier España, S.L. All rights reserved.

Bacterial cell motility of Burkholderia gut symbiont is required to colonize the insect gut.

PubMed

Lee, Jun Beom; Byeon, Jin Hee; Jang, Ho Am; Kim, Jiyeun Kate; Yoo, Jin Wook; Kikuchi, Yoshitomo; Lee, Bok Luel

2015-09-14

We generated a Burkholderia mutant, which is deficient of an N-acetylmuramyl-l-alanine amidase, AmiC, involved in peptidoglycan degradation. When non-motile ΔamiC mutant Burkholderia cells harboring chain form were orally administered to Riptortus insects, ΔamiC mutant cells were unable to establish symbiotic association. But, ΔamiC mutant complemented with amiC gene restored in vivo symbiotic association. ΔamiC mutant cultured in minimal medium restored their motility with single-celled morphology. When ΔamiC mutant cells harboring single-celled morphology were administered to the host insect, this mutant established normal symbiotic association, suggesting that bacterial motility is essential for the successful symbiosis between host insect and Burkholderia symbiont. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Hydrogen passivation of poly-Si/SiO x contacts for Si solar cells using Al 2O 3 studied with deuterium

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

Schnabel, Manuel; van de Loo, Bas W. H.; Nemeth, William

Here, the interplay between hydrogenation and passivation of poly-Si/SiO x contacts to n-type Si wafers is studied using atomic layer deposited Al 2O 3 and anneals in forming gas and nitrogen. The poly-Si/SiO x stacks are prepared by thermal oxidation followed by thermal crystallization of a-Si:H films deposited by plasma-enhanced chemical vapor deposition. Implied open-circuit voltages as high as 710 mV are achieved for p-type poly-Si/SiO x contacts to n-type Si after hydrogenation. Correlating minority carrier lifetime data and secondary ion mass spectrometry profiles reveals that the main benefit of Al 2O 3 is derived from its role as amore » hydrogen source for chemically passivating defects at SiO x; Al 2O 3 layers are found to hydrogenate poly-Si/SiO x much better than a forming gas anneal. By labelling Al 2O 3 and the subsequent anneal with different hydrogen isotopes, it is found that Al 2O 3 exchanges most of its hydrogen with the ambient upon annealing at 400 °C for 1 h even though there is no significant net change in its total hydrogen content.« less

Hydrogen passivation of poly-Si/SiOx contacts for Si solar cells using Al2O3 studied with deuterium

NASA Astrophysics Data System (ADS)

Schnabel, Manuel; van de Loo, Bas W. H.; Nemeth, William; Macco, Bart; Stradins, Paul; Kessels, W. M. M.; Young, David L.

2018-05-01

The interplay between hydrogenation and passivation of poly-Si/SiOx contacts to n-type Si wafers is studied using atomic layer deposited Al2O3 and anneals in forming gas and nitrogen. The poly-Si/SiOx stacks are prepared by thermal oxidation followed by thermal crystallization of a-Si:H films deposited by plasma-enhanced chemical vapor deposition. Implied open-circuit voltages as high as 710 mV are achieved for p-type poly-Si/SiOx contacts to n-type Si after hydrogenation. Correlating minority carrier lifetime data and secondary ion mass spectrometry profiles reveals that the main benefit of Al2O3 is derived from its role as a hydrogen source for chemically passivating defects at SiOx; Al2O3 layers are found to hydrogenate poly-Si/SiOx much better than a forming gas anneal. By labelling Al2O3 and the subsequent anneal with different hydrogen isotopes, it is found that Al2O3 exchanges most of its hydrogen with the ambient upon annealing at 400 °C for 1 h even though there is no significant net change in its total hydrogen content.

Hydrogen passivation of poly-Si/SiO x contacts for Si solar cells using Al 2O 3 studied with deuterium

DOE PAGES

Schnabel, Manuel; van de Loo, Bas W. H.; Nemeth, William; ...

2018-05-14

Here, the interplay between hydrogenation and passivation of poly-Si/SiO x contacts to n-type Si wafers is studied using atomic layer deposited Al 2O 3 and anneals in forming gas and nitrogen. The poly-Si/SiO x stacks are prepared by thermal oxidation followed by thermal crystallization of a-Si:H films deposited by plasma-enhanced chemical vapor deposition. Implied open-circuit voltages as high as 710 mV are achieved for p-type poly-Si/SiO x contacts to n-type Si after hydrogenation. Correlating minority carrier lifetime data and secondary ion mass spectrometry profiles reveals that the main benefit of Al 2O 3 is derived from its role as amore » hydrogen source for chemically passivating defects at SiO x; Al 2O 3 layers are found to hydrogenate poly-Si/SiO x much better than a forming gas anneal. By labelling Al 2O 3 and the subsequent anneal with different hydrogen isotopes, it is found that Al 2O 3 exchanges most of its hydrogen with the ambient upon annealing at 400 °C for 1 h even though there is no significant net change in its total hydrogen content.« less

Investigation of the poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene]/indium tin oxide interface using photoemission spectroscopy

NASA Astrophysics Data System (ADS)

Lägel, B.; Beerbom, M. M.; Doran, B. V.; Lägel, M.; Cascio, A.; Schlaf, R.

2005-07-01

The interface between the luminescent polymer poly [2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and sputter-cleaned indium tin oxide (ITO) was investigated using photoemission spectroscopy in combination with in situ thin film deposition. MEH-PPV was deposited in high vacuum directly from toluene solution on the ITO substrate using a home-built electrospray thin-film deposition system. The deposition was carried out in multiple steps without breaking the vacuum. In between deposition steps the sample was characterized with x-ray and ultraviolet photoemission spectroscopy. The evaluation of the spectra sequence allowed the determination of the orbital lineup (charge injection barriers) at the interface, as well as the MEH-PPV growth mode at the interface.

Low loss poly-silicon for high performance capacitive silicon modulators.

PubMed

Douix, Maurin; Baudot, Charles; Marris-Morini, Delphine; Valéry, Alexia; Fowler, Daivid; Acosta-Alba, Pablo; Kerdilès, Sébastien; Euvrard, Catherine; Blanc, Romuald; Beneyton, Rémi; Souhaité, Aurélie; Crémer, Sébastien; Vulliet, Nathalie; Vivien, Laurent; Boeuf, Frédéric

2018-03-05

Optical properties of poly-silicon material are investigated to be integrated in new silicon photonics devices, such as capacitive modulators. Test structure fabrication is done on 300 mm wafer using LPCVD deposition: 300 nm thick amorphous silicon layers are deposited on thermal oxide, followed by solid phase crystallization anneal. Rib waveguides are fabricated and optical propagation losses measured at 1.31 µm. Physical analysis (TEM ASTAR, AFM and SIMS) are used to assess the origin of losses. Optimal deposition and annealing conditions have been defined, resulting in 400 nm-wide rib waveguides with only 9.2-10 dB/cm losses.

Template Synthesis of Nanostructured Polymeric Membranes by Inkjet Printing.

PubMed

Gao, Peng; Hunter, Aaron; Benavides, Sherwood; Summe, Mark J; Gao, Feng; Phillip, William A

2016-02-10

The fabrication of functional nanomaterials with complex structures has been serving great scientific and practical interests, but current fabrication and patterning methods are generally costly and laborious. Here, we introduce a versatile, reliable, and rapid method for fabricating nanostructured polymeric materials. The novel method is based on a combination of inkjet printing and template synthesis, and its utility and advantages in the fabrication of polymeric nanomaterials is demonstrated through three examples: the generation of polymeric nanotubes, nanowires, and thin films. Layer-by-layer-assembled nanotubes can be synthesized in a polycarbonate track-etched (PCTE) membrane by printing poly(allylamine hydrochloride) and poly(styrenesulfonate) sequentially. This sequential deposition of polyelectrolyte ink enables control over the surface charge within the nanotubes. By a simple change of the printing conditions, polymeric nanotubes or nanowires were prepared by printing poly(vinyl alcohol) in a PCTE template. In this case, the high-throughput nature of the method enables functional nanomaterials to be generated in under 3 min. Furthermore, we demonstrate that inkjet printing paired with template synthesis can be used to generate patterns comprised of chemically distinct nanomaterials. Thin polymeric films of layer-by-layer-assembled poly(allylamine hydrochloride) and poly(styrenesulfonate) are printed on a PCTE membrane. Track-etched membranes covered with the deposited thin films reject ions and can potentially be utilized as nanofiltration membranes. When the fabrication of these different classes of nanostructured materials is demonstrated, the advantages of pairing template synthesis with inkjet printing, which include fast and reliable deposition, judicious use of the deposited materials, and the ability to design chemically patterned surfaces, are highlighted.

Di-p-xylylene polymer and method for making the same

DOEpatents

Jahn, Randy K.; Liepins, Raimond

1985-01-01

A method and apparatus for forming an improved poly-p-xylylene film. Solid di-para-xylylene dimer is sublimed in a sublimation furnace at approximately 100.degree. to 200.degree. C. and subsequently conducted to a pyrolysis furnace where it is pyrolyzed to the diradical p-xylylene monomer while in the vapor state at approximately 600 degrees C. The diradical monomer is then introduced into a deposition chamber for deposition onto a suitable substrate. The deposition chamber includes electrodes for producing a low pressure plasma through which the diradical monomer passes prior to deposition. The interaction of the diradical monomer with the low pressure plasma results in the formation of poly-p-xylylene film which is exceptionally hard and thermally stable.

Poly(glycidyl methacrylate)-A soft template for the facile preparation of poly(glycidyl methacrylate) core-copper nanoparticle shell nanocomposite

NASA Astrophysics Data System (ADS)

Mohammed Safiullah, S.; Abdul Wasi, K.; Anver Basha, K.

2015-12-01

Poly(glycidyl methacrylate) core/copper nanoparticle shell nanocomposite (PGMA/Cu nanohybrid) was prepared by simple two step method (i) The synthesis of poly(glycidyl methacrylate) (PGMA) beads by free radical suspension polymerization followed by (ii) direct deposition of copper nanoparticles (CuNPs) on activated PGMA beads. The PGMA beads were used as a soft template to host the CuNPs without surface modification of it. In this method the CuNPs were formed by chemical reduction of copper salts using sodium borohydride in water medium and deposited directly on the activated PGMA. Two different concentrations of copper salts were employed to know the effect of concentration on the shape and size of nanoparticles. The results showed that, the different sizes and shapes of CuNPs were deposited on the PGMA matrix. The X-ray Diffraction study results showed that the CuNPs were embedded on the surface of the PGMA matrix. The scanning electron microscopic images revealed that the fabrication of CuNPs on the PGMA matrix possess different shapes and changes the morphology and nature of PGMA beads significantly. The fluorescent micrograph also confirmed that the CuNPs were doped on the PGMA surface. The thermal studies have demonstrated that the CuNPs deposition on the surface of PGMA beads had a significant effect.

Selective aggressiveness in European free-tailed bats ( Tadarida teniotis): influence of familiarity, age and sex

NASA Astrophysics Data System (ADS)

Ancillotto, Leonardo; Russo, Danilo

2014-03-01

Bats are highly social mammals that often form large groups and represent good models to test the role played by individual status in shaping social relationships. Social cohesion relies on the ability of group and individual recognition, which is mediated by a range of sensorial cues. In this study, we selected the European free-tailed bat Tadarida teniotis as a model species to test the effects of familiarity, sex and age on aggressiveness and mutual tolerance. We hypothesize that T. teniotis is able to recognize group members and exhibit selective aggressiveness, and thus we predict fewer aggressive events and more amicable encounters between colony mates than between strangers. As female bats are generally more sociable and perform prolonged parental care to juveniles even after weaning, we hypothesize that sex and age of bats have significant influences on aggressive behaviours and thus predict that females will perform more amicable behaviours than males and that adults of both sexes will be less aggressive towards juveniles. Our results confirm that T. teniotis is able to discriminate between familiar and stranger individuals, showing higher rates of aggressive behaviours towards the latter. Females are more prone to exhibit amicable behaviours, particularly during same-sex interactions, while males show higher level of aggressiveness. Juveniles are subjected to fewer aggressive behaviours by adults of both sexes. Familiarity appears crucial for T. teniotis in determining the degree of aggressiveness during social interactions but the rate of aggressive events is also influenced by intrinsic individual factors such as sex and age.

UV-light assisted patterned metallization of textile fabrics

NASA Astrophysics Data System (ADS)

Bahners, Thomas; Gebert, Beate; Prager, Andrea; Hartmann, Nils; Hagemann, Ulrich; Gutmann, Jochen S.

2018-04-01

A UV-assisted process allows full-faced or local deposition of silver domains on textiles made of natural as well as synthetic fibers, which act as nuclei for subsequent galvanic metallization. SEM and XPS analyses indicate that the process generates particulate depositions - particles, aggregates - of elementary silver. Masking the UV irradiation confines silver deposition strictly to the exposed areas thus allowing patterning. Adhesion of the deposited silver is high on the studied natural fiber cotton and polyamide fibers. Adhesion on smooth and chemically inert synthethic fibers such as, e.g., poly(ethylene terephthalate) or para- and meta-aramids could be enhanced by finishing with poly(vinylamine) thus providing complex-forming amino groups. Although the process does not deposit a closed, electrically conducting layer, all studied samples could be metallized by galvanization. The resulting metal coatings exhibit high conductivity and wash stability. Following a patterned silver deposition, the subsequent galvanic metallization produced conductive patterns of identical geometry thus opening an avenue towards printed circuits on textile fabrics.

Fabrication and characterization of low temperature polycrystalline silicon thin film transistors

NASA Astrophysics Data System (ADS)

Krishnan, Anand Thiruvengadathan

2000-10-01

The proliferation of devices with built-in displays, such as personal digital assistants and cellular phones has created a demand for rugged light-weight displays. Polymeric substrates could be suited for these applications, and they offer the possibility of flexible displays also. However, driver circuitry needs to be integrated in the display if the cost is to be reduced. Low temperature (<350°C) polycrystalline silicon (poly-Si) thin film transistors, if developed, offer driver circuitry integration during pixel transistor fabrication on top of flexible substrates. This thesis addresses several issues related to the fabrication of thin film transistors at low temperatures on glass substrates. A high-density plasma (electron cyclotron resonance (ECR)) based approach was adopted for deposition of thin films. A process for deposition of n-type doped silicon (n-type doped Si) at T < 350°C and having resistivity <1 ohm/cm has been developed. Intrinsic poly-Si was deposited under different conditions of microwave power, RF bias and deposition times. The properties of n-type doped Si and intrinsic poly-Si were correlated with the structure and the deposition conditions. A novel TFT structure has been proposed and implemented in this work. This top gate TFT structure uses n-type doped Si and utilizes only two masks and one alignment step. There are no critical etch steps and good interface quality could be obtained even without post-processing hydrogenation as the poly-Si surface was not exposed to air before deposition of the gate dielectric. TFTs using this top gate structure were fabricated with no process step exceeding 340°C electrode temperature (surface temperature <300°C). These TFTs show ON/OFF ratios in excess of 105. Their sub-threshold swing is ˜0.5 V/decade and mobility is 1--10 cm2/V-s. Several TFTs were also fabricated using alternative dielectrics such as oxide deposited from tetramethyl silane in an RFPECVD chamber and silicon nitride deposited in the ECR and these TFTs also show reasonable device characteristics. TFTs processed using this high-density plasma based approach show great potential for use in applications such as driver circuitry integration on low temperature substrates.

A study of thermal transitions in a new semicrystalline thermoplastic polyimide

NASA Technical Reports Server (NTRS)

Pratt, J. Richard; St.clair, Terry L.; Gerber, Margaret K.; Gautreaux, Carol R.

1988-01-01

A polyimide derive from 4,4'-isophthaloyl diphthalic anhydride (IDPA) and 1,3-bis (4-aminophenoxy 4'-benzoyl) benzene (1,3-BABB) having semicrystalline behavior was prepared and characterized by differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXS). Thus a poly(amic acid) film cured in air for one hour each at 100 and 200 C displayed an endotherm at 286 C, followed by a crystallization exotherm at 317 C, and a second melting transition at 350 C. The 286 C melting point appeared to result from earlier solvent-induced crystallization. Films cast from DMAc, air dried, and soaked in methylene chloride could not be induced into semicrystallinity. The fully cured polyimide has a Tg of 216 C. Films heated to temperatures as high as 100 C for one hour in air were transparent and light yellow in color. Those films heated to or above 125 C were translucent. Polarized light microscopy revealed the presence of spherulites 608 micrometers in diameter in a sample cured to 275 C in air. Two film samples, one cured to 275 and the other to 325 C, were evaluated for tensile and ultimate strength, modulus, and percent elongation at 25 and 200 C. These values remained essentially constant at each test temperature.

FAST TRACK COMMUNICATION: Poly(methyl methacrylate)-palladium clusters nanocomposite formation by supersonic cluster beam deposition: a method for microstructured metallization of polymer surfaces

NASA Astrophysics Data System (ADS)

Ravagnan, Luca; Divitini, Giorgio; Rebasti, Sara; Marelli, Mattia; Piseri, Paolo; Milani, Paolo

2009-04-01

Nanocomposite films were fabricated by supersonic cluster beam deposition (SCBD) of palladium clusters on poly(methyl methacrylate) (PMMA) surfaces. The evolution of the electrical conductance with cluster coverage and microscopy analysis show that Pd clusters are implanted in the polymer and form a continuous layer extending for several tens of nanometres beneath the polymer surface. This allows the deposition, using stencil masks, of cluster-assembled Pd microstructures on PMMA showing a remarkably high adhesion compared with metallic films obtained by thermal evaporation. These results suggest that SCBD is a promising tool for the fabrication of metallic microstructures on flexible polymeric substrates.

Star-shaped polymers of bio-inspired algae core and poly(acrylamide) and poly(acrylic acid) as arms in dissolution of silica/silicate.

PubMed

Chauhan, Kalpana; Patiyal, Priyanka; Chauhan, Ghanshyam S; Sharma, Praveen

2014-06-01

Silica, in natural waters (due to weathering of rocks) decreases system performance in water processing industry due to scaling. In view of that, the present work involves the synthesis of novel green star shaped additives of algae core (a bio-inspired material as diatom maintains silicic acid equilibrium in sea water) as silica polymerization inhibitors. Star shaped materials with bio-inspired core and poly(acrylamide) [poly(AAm)] and poly(acrylic acid) [poly(AAc)] arms were synthesized by economical green approach. The proficiency was evaluated in 'mini lab' scale for the synthesized APAAm (Algae-g-poly(AAm)) and APAAc (Algae-g-poly(AAc)) dendrimers (star shaped) in colloidal silica mitigation/inhibition at 35 °C and 55 °C. Synthesized dendrimers were equally proficient in silica inhibition at 12 h and maintains ≥450 ppm soluble silica. However, APAAm dendrimers of generation 0 confirmed better results (≈300 ppm) in contrast to APAAc dendrimers in silica inhibition at 55 °C. Additionally, dendrimers also worked as a nucleator for heterogeneous polymerization to inhibit silica homo-polymerization. APAAm dendrimer test set showed no silica deposit for more than 10 days of inhibition. EDX characterization results support nucleator mechanism with Si content of 6.97%-10.98% by weight in silica deposits (SiO2-APAAm dendrimer composites). Copyright © 2014 Elsevier Ltd. All rights reserved.

Robust Functionalization of Large Microelectrode Arrays by Using Pulsed Potentiostatic Deposition

PubMed Central

Rothe, Joerg; Frey, Olivier; Madangopal, Rajtarun; Rickus, Jenna; Hierlemann, Andreas

2016-01-01

Surface modification of microelectrodes is a central step in the development of microsensors and microsensor arrays. Here, we present an electrodeposition scheme based on voltage pulses. Key features of this method are uniformity in the deposited electrode coatings, flexibility in the overall deposition area, i.e., the sizes and number of the electrodes to be coated, and precise control of the surface texture. Deposition and characterization of four different materials are demonstrated, including layers of high-surface-area platinum, gold, conducting polymer poly(ethylenedioxythiophene), also known as PEDOT, and the non-conducting polymer poly(phenylenediamine), also known as PPD. The depositions were conducted using a fully integrated complementary metal-oxide-semiconductor (CMOS) chip with an array of 1024 microelectrodes. The pulsed potentiostatic deposition scheme is particularly suitable for functionalization of individual electrodes or electrode subsets of large integrated microelectrode arrays: the required deposition waveforms are readily available in an integrated system, the same deposition parameters can be used to functionalize the surface of either single electrodes or large arrays of thousands of electrodes, and the deposition method proved to be robust and reproducible for all materials tested. PMID:28025569

Poly(cyclohexylethylene)- block -Poly(lactide) Oligomers for Ultrasmall Nanopatterning Using Atomic Layer Deposition

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

Yao, Li; Oquendo, Luis E.; Schulze, Morgan W.

2016-03-08

Poly(cyclohexylethylene)-block-poly(lactide) (PCHE–PLA) block polymers were synthesized through a combination of anionic polymerization, heterogeneous catalytic hydrogenation and controlled ring-opening polymerization. Ordered thin films of PCHE–PLA with ultrasmall hexagonally packed cylinders oriented perpendicularly to the substrate surface were prepared by spin-coating and subsequent solvent vapor annealing for use in two distinct templating strategies. In one approach, selective hydrolytic degradation of the PLA domains generated nanoporous PCHE templates with an average pore diameter of 5 ± 1 nm corroborated by atomic force microscopy and grazing incidence small-angle X-ray scattering. Alternatively, sequential infiltration synthesis (SIS) was employed to deposit Al2O3 selectively into the PLAmore » domains of PCHE–PLA thin films. A combination of argon ion milling and O2 reactive ion etching (RIE) enabled the replication of the Al2O3 nanoarray from the PCHE–PLA template on diverse substrates including silicon and gold with feature diameters less than 10 nm.« less

3D solid supported inter-polyelectrolyte complexes obtained by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate)

PubMed Central

Maestro, Armando; Llamas, Sara; Álvarez-Rodríguez, Jesús; Ortega, Francisco; Maroto-Valiente, Ángel

2016-01-01

Summary This work addresses the formation and the internal morphology of polyelectrolyte layers obtained by the layer-by-layer method. A multimodal characterization showed the absence of stratification of the films formed by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate). Indeed the final organization might be regarded as three-dimensional solid-supported inter-polyelectrolyte films. The growth mechanism of the multilayers, followed using a quartz crystal microbalance, evidences two different growth trends, which show a dependency on the ionic strength due to its influence onto the polymer conformation. The hydration state does not modify the multilayer growth, but it contributes to the total adsorbed mass of the film. The water associated with the polyelectrolyte films leads to their swelling and plastification. The use of X-ray photoelectron spectroscopy has allowed for deeper insights on the internal structure and composition of the polyelectrolyte multilayers. PMID:26977377

3D solid supported inter-polyelectrolyte complexes obtained by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate).

PubMed

Guzmán, Eduardo; Maestro, Armando; Llamas, Sara; Álvarez-Rodríguez, Jesús; Ortega, Francisco; Maroto-Valiente, Ángel; Rubio, Ramón G

2016-01-01

This work addresses the formation and the internal morphology of polyelectrolyte layers obtained by the layer-by-layer method. A multimodal characterization showed the absence of stratification of the films formed by the alternate deposition of poly(diallyldimethylammonium chloride) and poly(sodium 4-styrenesulfonate). Indeed the final organization might be regarded as three-dimensional solid-supported inter-polyelectrolyte films. The growth mechanism of the multilayers, followed using a quartz crystal microbalance, evidences two different growth trends, which show a dependency on the ionic strength due to its influence onto the polymer conformation. The hydration state does not modify the multilayer growth, but it contributes to the total adsorbed mass of the film. The water associated with the polyelectrolyte films leads to their swelling and plastification. The use of X-ray photoelectron spectroscopy has allowed for deeper insights on the internal structure and composition of the polyelectrolyte multilayers.

76 FR 64124 - Implementation of the Alternative Dispute Resolution Program

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-17

... Register notice (FRN) for public comment. The NRC's ADR Program is comprised of two entirely different sub... safety conscious work environment by facilitating timely and amicable resolution of discrimination concerns without resorting to prolonged litigation and unnecessary expenses. The second sub-program...

Design and application of ion-implanted polySi passivating contacts for interdigitated back contact c-Si solar cells

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

Yang, Guangtao; Ingenito, Andrea; Hameren, Nienke van

2016-01-18

Ion-implanted passivating contacts based on poly-crystalline silicon (polySi) are enabled by tunneling oxide, optimized, and used to fabricate interdigitated back contact (IBC) solar cells. Both n-type (phosphorous doped) and p-type (boron doped) passivating contacts are fabricated by ion-implantation of intrinsic polySi layers deposited via low-pressure chemical vapor deposition and subsequently annealed. The impact of doping profile on the passivation quality of the polySi doped contacts is studied for both polarities. It was found that an excellent surface passivation could be obtained by confining as much as possible the implanted-and-activated dopants within the polySi layers. The doping profile in the polySimore » was controlled by modifying the polySi thickness, the energy and dose of ion-implantation, and the temperature and time of annealing. An implied open-circuit voltage of 721 mV for n-type and 692 mV for p-type passivating contacts was achieved. Besides the high passivating quality, the developed passivating contacts exhibit reasonable high conductivity (R{sub sh n-type} = 95 Ω/□ and R{sub sh p-type} = 120 Ω/□). An efficiency of 19.2% (V{sub oc} = 673 mV, J{sub sc} = 38.0 mA/cm{sup 2}, FF = 75.2%, and pseudo-FF = 83.2%) was achieved on a front-textured IBC solar cell with polySi passivating contacts as both back surface field and emitter. By improving the front-side passivation, a V{sub OC} of 696 mV was also measured.« less

Stress Analysis of SiC MEMS Using Raman Spectroscopy

NASA Astrophysics Data System (ADS)

Ness, Stanley J.; Marciniak, M. A.; Lott, J. A.; Starman, L. A.; Busbee, J. D.; Melzak, J. M.

2003-03-01

During the fabrication of Micro-Electro-Mechanical Systems (MEMS), residual stress is often induced in the thin films that are deposited to create these systems. These stresses can cause the device to fail due to buckling, curling, or fracture. Industry is looking for ways to characterize the stress during the deposition of thin films in order to reduce or eliminate device failure. Micro-Raman spectroscopy has been successfully used to characterize poly-Si MEMS devices made with the MUMPS® process. Raman spectroscopy was selected because it is nondestructive, fast and has the potential for in situ stress monitoring. This research attempts to use Raman spectroscopy to analyze the stress in SiC MEMS made with the MUSiC® process. Raman spectroscopy is performed on 1-2-micron-thick SiC thin films deposited on silicon, silicon nitride, and silicon oxide substrates. The most common poly-type of SiC found in thin film MEMS made with the MUSiC® process is 3C-SiC. Research also includes baseline spectra of 6H, 4H, and 15R poly-types of bulk SiC.

Polyalanine expansions drive a shift into α-helical clusters without amyloid-fibril formation.

PubMed

Polling, Saskia; Ormsby, Angelique R; Wood, Rebecca J; Lee, Kristie; Shoubridge, Cheryl; Hughes, James N; Thomas, Paul Q; Griffin, Michael D W; Hill, Andrew F; Bowden, Quill; Böcking, Till; Hatters, Danny M

2015-12-01

Polyglutamine (polyGln) expansions in nine human proteins result in neurological diseases and induce the proteins' tendency to form β-rich amyloid fibrils and intracellular deposits. Less well known are at least nine other human diseases caused by polyalanine (polyAla)-expansion mutations in different proteins. The mechanisms of how polyAla aggregates under physiological conditions remain unclear and controversial. We show here that aggregation of polyAla is mechanistically dissimilar to that of polyGln and hence does not exhibit amyloid kinetics. PolyAla assembled spontaneously into α-helical clusters with diverse oligomeric states. Such clustering was pervasive in cells irrespective of visible aggregate formation, and it disrupted the normal physiological oligomeric state of two human proteins natively containing polyAla: ARX and SOX3. This self-assembly pattern indicates that polyAla expansions chronically disrupt protein behavior by imposing a deranged oligomeric status.

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

DOE PAGES

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph; ...

2018-02-06

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Molecular weight dependent structure and charge transport in MAPLE-deposited poly(3-hexylthiophene) thin films

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

Dong, Ban Xuan; Smith, Mitchell; Strzalka, Joseph

In this work, poly(3-hexylthiophene) (P3HT) films prepared using the matrix-assisted pulsed laser evaporation (MAPLE) technique are shown to possess morphological structures that are dependent on molecular weight (MW). Specifically, the structures of low MW samples of MAPLE-deposited film are composed of crystallites/aggregates embedded within highly disordered environments, whereas those of high MW samples are composed of aggregated domains connected by long polymer chains. Additionally, the crystallite size along the side-chain (100) direction decreases, whereas the conjugation length increases with increasing molecular weight. This is qualitatively similar to the structure of spin-cast films, though the MAPLE-deposited films are more disordered. In-planemore » carrier mobilities in the MAPLE-deposited samples increase with MW, consistent with the notion that longer chains bridge adjacent aggregated domains thereby facilitating more effective charge transport. The carrier mobilities in the MAPLE-deposited simples are consistently lower than those in the solvent-cast samples for all molecular weights, consistent with the shorter conjugation length in samples prepared by this deposition technique.« less

Competition and Cooperation: Evil Twins or Fated Lovers?

ERIC Educational Resources Information Center

Fitch, Frank; Loving, Greg

2007-01-01

The competing global forces of homogenizing commercialism and absolutist sectarianism continue to engender a regime of fear and have all but eclipsed what John Dewey called the democratic "habit of amicable cooperation." The values of cooperation are increasingly seen as "unrealistic" and even taken as signs of weakness in the…

Monument to Lack: The New University

ERIC Educational Resources Information Center

Jones, Andee

2015-01-01

The present article is the fourth in an unintended series charting the author's experiences of academic censure via social exclusion, or "amicable exclusion" as the Vietnamese reprint has it (Jones, 2012, 2013, 2014). Here in talking about academic censure, Jones touches on former psychoanalyst Jeffrey Mason's (1990) excoriation by the…

SOLUBILITY OF ORGANIC BIOCIDES IN SUPERCRITICAL CO2 AND CO2+ COSOLVENT MIXTURES

EPA Science Inventory

Solubilities of four organic biocides in supercritical carbon dioxide (Sc-CO2) were measured using a dynamic flowr apparatus over a pressure range of 10 to 30 MPa and temperature of 35-80 degrees C. The biocides studied were: Amical-48 (diiodomethyl p-tolyl sulfone), chlorothalo...

En-Route Care Capability from Point of Injury Impacts Mortality after Severe Wartime Injury

DTIC Science & Technology

2013-02-01

tranexamic acid .5,6 The greatest proportion of com- bat deaths, however, continue to occur in the prehospital setting, with noncompressible torso...Morrison JJ, DuBose JJ, Rasmussen TE, et al. Military Application of Tranex- amic acid in Trauma Emergency Resuscitation (MATTERs) Study. Arch Surg

9 CFR 202.104 - Rule 4: Agency action.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Rule 4: Agency action. 202.104 Section 202.104 Animals and Animal Products GRAIN INSPECTION, PACKERS AND STOCKYARDS ADMINISTRATION (PACKERS... parties to an amicable or informal adjustment of the matter by communication with the parties or their...

9 CFR 202.104 - Rule 4: Agency action.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Rule 4: Agency action. 202.104 Section 202.104 Animals and Animal Products GRAIN INSPECTION, PACKERS AND STOCKYARDS ADMINISTRATION (PACKERS... parties to an amicable or informal adjustment of the matter by communication with the parties or their...

Simple, green, and clean removal of a poly(methyl methacrylate) film on chemical vapor deposited graphene

NASA Astrophysics Data System (ADS)

Park, J.-H.; Jung, W.; Cho, D.; Seo, J.-T.; Moon, Y.; Woo, S. H.; Lee, C.; Park, C.-Y.; Ahn, J. R.

2013-10-01

The clean removal of a poly(methyl methacrylate) (PMMA) film on graphene has been an essential part of the process of transferring chemical vapor deposited graphene to a specific substrate, influencing the quality of the transferred graphene. Here we demonstrate that the clean removal of PMMA can be achieved by a single heat-treatment process without the chemical treatment that was adopted in other methods of PMMA removal. The cleanness of the transferred graphene was confirmed by four-point probe measurements, synchrotron radiation x-ray photoemission spectroscopy, optical images, and Raman spectroscopy.

New type of dummy layout pattern to control ILD etch rate

NASA Astrophysics Data System (ADS)

Pohland, Oliver; Spieker, Julie; Huang, Chih-Ta; Govindaswamy, Srikanth; Balasinski, Artur

2007-12-01

Adding dummy features (waffles) to drawn geometries of the circuit layout is a common practice to improve its manufacturability. As an example, local dummy pattern improves MOSFET line and space CD control by adjusting short range optical proximity and reducing the aggressiveness of its correction features (OPC) to widen the lithography process window. Another application of dummy pattern (waffles) is to globally equalize layout pattern density, to reduce long-range inter-layer dielectric (ILD) thickness variations after the CMP process and improve contact resistance uniformity over the die area. In this work, we discuss a novel type of dummy pattern with a mid-range interaction distance, to control the ILD composition driven by its deposition and etch process. This composition is reflected on sidewall spacers and depends on the topography of the underlying poly pattern. During contact etch, it impacts the etch rate of the ILD. As a result, the deposited W filling the damascene etched self-aligned trench contacts in the ILD may electrically short to the underlying gates in the areas of isolated poly. To mitigate the dependence of the ILD composition on poly pattern distribution, we proposed a special dummy feature generation with the interaction range defined by the ILD deposition and etch process. This helped equalize mid-range poly pattern density without disabling the routing capability with damascene trench contacts in the periphery which would have increased the layout footprint.

Glucose Oxidase Adsorption on Sequential Adsorbed Polyelectrolyte Films Studied by Spectroscopic Techniques

NASA Astrophysics Data System (ADS)

Tristán, Ferdinando; Solís, Araceli; Palestino, Gabriela; Gergely, Csilla; Cuisinier, Frédéric; Pérez, Elías

2005-04-01

The adsorption of Glucose Oxidase (GOX) on layers of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) deposited on Sequentially Adsorbed Polyelectrolyte Films (SAPFs) were studied by three different spectroscopic techniques. These techniques are: Optical Wave Light Spectroscopy (OWLS) to measure surface density; Fluorescence Resonance Energy Transfer (FRET) to verify the adsorption of GOX on the surface; and Fourier Transform Infrared Spectroscopy in Attenuated Total Reflection mode (FTIR-HATR) to inspect local structure of polyelectrolytes and GOX. Two positive and two negative polyelectrolytes are used: Cationic poly(ethyleneimine) (PEI) and poly(allylamine hydrochloride) (PAH) and anionic poly(sodium 4-styrene sulfonate) (PSS) and poly(acrylic acid) (PAA). These spectroscopic techniques do not require any labeling for GOX or SAPFs, specifically GOX and PSS are naturally fluorescent and are used as a couple donor-acceptor for the FRET technique. The SAPFs are formed by a (PEI)-(PSS/PAH)2 film followed by (PAA/PAH)n bilayers. GOX is finally deposited on top of SAPFs at different values of n (n=1..5). Our results show that GOX is adsorbed on positive ended SAPFs forming a monolayer. Contrary, GOX adsorption is not observed on negative ended film polyelectrolyte. GOX stability was tested adding a positive and a negative polyelectrolyte after GOX adsorption. Protein is partially removed by PAH and PAA, with lesser force by PAA.

Poly(vinyl alcohol)/cellulose nanofibril hybrid aerogels with an aligned microtubular porous structure and their composites with polydimethylsiloxane

Treesearch

Tianliang Zhai; Qifeng Zheng; Zhiyong Cai; Lih-Sheng Turng; Hesheng Xia; Shaoqin Gong

2015-01-01

Superhydrophobic poly(vinyl alcohol) (PVA)/ cellulose nanofibril (CNF) aerogels with a unidirectionally aligned microtubular porous structure were prepared using a unidirectional freeze-drying process, followed by the thermal chemical vapor deposition of methyltrichlorosilane. The silanized aerogels were characterized using various techniques including scanning...

Tailored adhesion behavior of polyelectrolyte thin films deposited on plasma-treated poly(dimethylsiloxane) for functionalized membranes

NASA Astrophysics Data System (ADS)

Bassil, Joelle; Alem, Halima; Henrion, Gérard; Roizard, Denis

2016-04-01

Completely homogenous films formed via the layer-by-layer assembly of poly(diallyldimethylammonium chloride) (PDADMAC) and the poly(styrene sulfonate) were successfully obtained on plasma-treated poly(dimethylsiloxane) (PDMS) substrates. To modify the hydrophobicity of the PDMS surface, a cold plasma treatment was previously applied to the membrane, which led to the creation of hydrophilic groups on the surface of the membrane. PDMS wettability and surface morphology were successfully correlated with the plasma parameters. A combination of contact angle measurements, scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis was used to demonstrate that homogeneous and hydrophilic surfaces could be achieved on PDMS cold-plasma-treated membranes. The stability of the assembled PEL layer on the PDMS was evaluated using a combination of pull-off testing and X-ray photoelectron spectroscopy (XPS), which confirmed the relevance of a plasma pre-treatment as the adhesion of the polyelectrolyte multilayers was greatly enhanced when the deposition was completed on an activated PDMS surface at 80 W for 5 min.

Radiation induced deposition of copper nanoparticles inside the nanochannels of poly(acrylic acid)-grafted poly(ethylene terephthalate) track-etched membranes

NASA Astrophysics Data System (ADS)

Korolkov, Ilya V.; Güven, Olgun; Mashentseva, Anastassiya A.; Atıcı, Ayse Bakar; Gorin, Yevgeniy G.; Zdorovets, Maxim V.; Taltenov, Abzal A.

2017-01-01

Poly(ethylene terephthalate) PET, track-etched membranes (TeMs) with 400 nm average pore size were UV-grafted with poly(acrylic acid) (PAA) after oxidation of inner surfaces by H2O2/UV system. Carboxylate groups of grafted PAA chains were easily complexed with Cu2+ ions in aqueous solutions. These ions were converted into metallic copper nanoparticles (NPs) by radiation-induced reduction of copper ions in aqueous-alcohol solution by gamma rays in the dose range of 46-250 kGy. Copper ions chelating with -COOH groups of PAA chains grafted on PET TeMs form polymer-metal ion complex that prevent the formation of agglomerates during reduction of copper ions to metallic nanoparticles. The detailed analysis by X-Ray diffraction technique (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the deposition of copper nanoparticles with the average size of 70 nm on the inner surface of nanochannels of PET TeMs. Samples were also investigated by FTIR, ESR spectroscopies to follow copper ion reduction.

Effects of a capping oxide layer on polycrystalline-silicon thin-film transistors fabricated by continuous-wave laser crystallization

NASA Astrophysics Data System (ADS)

Li, Yi-Shao; Wu, Chun-Yi; Chou, Chia-Hsin; Liao, Chan-Yu; Chuang, Kai-Chi; Luo, Jun-Dao; Li, Wei-Shuo; Cheng, Huang-Chung

2018-06-01

A tetraethyl-orthosilicate (TEOS) capping oxide was deposited by low-pressure chemical vapor deposition (LPCVD) on a 200-nm-thick amorphous Si (a-Si) film as a heat reservoir to improve the crystallinity and surface roughness of polycrystalline silicon (poly-Si) formed by continuous-wave laser crystallization (CLC). The effects of four thicknesses of the capping oxide layer to satisfy an antireflection condition, namely, 90, 270, 450, and 630 nm, were investigated. The largest poly-Si grain size of 2.5 × 20 µm2 could be achieved using a capping oxide layer with an optimal thickness of 450 nm. Moreover, poly-Si nanorod (NR) thin-film transistors (TFTs) fabricated using the aforementioned technique exhibited a superior electron field-effect mobility of 1093.3 cm2 V‑1 s‑1 and an on/off current ratio of 2.53 × 109.

The Good, the Bad, and the Ugly: Divorced Mothers' Experiences with Coparenting

ERIC Educational Resources Information Center

Markham, Melinda Stafford; Coleman, Marilyn

2012-01-01

This study produces a grounded theory of how 20 predominantly White, well-educated women experienced sharing physical custody of their children with their former partners after divorce or separation. Three patterns of coparenting were identified in the data: "continuously contentious", "always amicable", and "bad to better". Five negative factors…

Air-stable solution-processed n-channel organic thin film transistors with polymerenhanced morphology

DOE PAGES

He, Zhengran; Shaik, Shoieb; Bi, Sheng; ...

2015-05-04

N,N 0-1H,1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN 2) is an n-type semiconductor exhibiting high electron mobility and excellent air stability. However, the reported electron mobility based on spin-coated PDIF-CN 2 film is much lower than the value of PDIF-CN 2 single crystals made from vapor phase deposition, indicating significant room for mobility enhancement. In this study, various insulating polymers, including poly(vinyl alcohol), poly(methyl methacrylate) (PMMA), and poly(alpha-methylstyrene) (PaMS), are pre-coated on silicon substrate aiming to enhance the morphology of the PDIF-CN 2 thin film, thereby improving the charge transport and air stability. Atomic force microscopy images reveal that with the pre-deposition of PaMSmore » or PMMA polymers, the morphology of the PDIF-CN 2 polycrystalline films is optimized in semiconducting crystal connectivity, domain size, and surface roughness, which leads to significant improvement of organic thin-film transistor (OTFT) performance. Particularly, an electron mobility of up to 0.55 cm 2/V s has been achieved from OTFTs based on the PDIF-CN 2 film with the pre-deposition of PaMS polymer.« less

Multi-material poly(lactic acid) scaffold fabricated via fused deposition modeling and direct hydroxyapatite injection as spacers in laminoplasty

NASA Astrophysics Data System (ADS)

Syuhada, Ghifari; Ramahdita, Ghiska; Rahyussalim, A. J.; Whulanza, Yudan

2018-02-01

Nowadays, additive manufacturing method has been used extensively to realize any product with specific attributes rather than the conventional subtractive manufacturing method. For instance, the additive manufacturing has enable us to construct a product layer-by-layer by successively depositing several materials in one session and one platform. This paper studied the properties of a 3D printed scaffold fabricated through Poly(Lactic-acid) (PLA) deposition modelling in combination with injectable hydroxyapatite (HA)/alginate as cell carrier. The scaffold was designed to serve as a spacer in cervical laminoplasty. Therefore, a series of test were conducted to elaborate the mechanical property, porosity and in-vitro toxicity testing. The results showed that the method is reliable to fabricate the scaffold as desired although the toxicity test needs more confirmation.

Effect of tetramethylsilane flow on the deposition and tribological behaviors of silicon doped diamond-like carbon rubbed against poly(oxymethylene)

NASA Astrophysics Data System (ADS)

Deng, Xingrui; Lim, Yankuang; Kousaka, Hiroyuki; Tokoroyama, Takayuki; Umehara, Noritsugu

2014-11-01

In this study, silicon doped diamond-like carbon (Si-DLC) was deposited on stainless steel (JIS SUS304) by using surface wave-excited plasma (SWP). The effects of tetramethylsilane (TMS) flow on the composition, topography, mechanical properties and tribological behavior were investigated. Pin-on-disc tribo-meter was used to investigate the tribological behavior of the Si-DLC coating rubbed against poly(oxymethylene) (POM). The results show that the deposition rate, roughness of Si-DLC increased and the hardness of Si-DLC decreased with the increase of TMS flow rate from 2 to 4 sccm; the roughness increase therein led to the increase of ploughing term of friction. The increase of adhesion term was also seen with the increase of TMS flow rate, being attributed to the decrease of hydrogen concentration in the coating. It was considered that more POM transferred onto the Si-DLC deposited at higher TMS flow rate due to larger heat generation by friction.

Predictors of survival and ability to wean from short-term mechanical circulatory support device following acute myocardial infarction complicated by cardiogenic shock.

PubMed

Garan, A Reshad; Eckhardt, Christina; Takeda, Koji; Topkara, Veli K; Clerkin, Kevin; Fried, Justin; Masoumi, Amirali; Demmer, Ryan T; Trinh, Pauline; Yuzefpolskaya, Melana; Naka, Yoshifumi; Burkhoff, Dan; Kirtane, Ajay; Colombo, Paolo C; Takayama, Hiroo

2017-11-01

Cardiogenic shock following acute myocardial infarction (AMI-CS) portends a poor prognosis. Short-term mechanical circulatory support devices (MCSDs) provide hemodynamic support for patients with cardiogenic shock but predictors of survival and the ability to wean from short-term MCSDs remain largely unknown. All patients > 18 years old treated at our institution with extra-corporeal membrane oxygenation or short-term surgical ventricular assist device for AMI-CS were studied. We collected acute myocardial infarction details with demographic and hemodynamic variables. Primary outcomes were survival to discharge and recovery from MCSD (i.e. survival without heart replacement therapy including durable ventricular assist device or heart transplant). One hundred and twenty-four patients received extra-corporeal membrane oxygenation or short-term surgical ventricular assist device following acute myocardial infarction from 2007 to 2016; 89 received extra-corporeal membrane oxygenation and 35 short-term ventricular assist device. Fifty-five (44.4%) died in the hospital and 69 (55.6%) survived to discharge. Twenty-six (37.7%) required heart replacement therapy (four transplant, 22 durable ventricular assist device) and 43 (62.3%) were discharged without heart replacement therapy. Age and cardiac index at MCSD implantation were predictors of survival to discharge; patients over 60 years with cardiac index <1.5 l/min per m 2 had a low likelihood of survival. The angiographic result after revascularization predicted recovery from MCSD (odds ratio 9.00, 95% confidence interval 2.45-32.99, p=0.001), but 50% of those optimally revascularized still required heart replacement therapy. Cardiac index predicted recovery from MCSD among this group (odds ratio 4.06, 95% confidence interval 1.45-11.55, p=0.009). Among AMI-CS patients requiring short-term MCSDs, age and cardiac index predict survival to discharge. Angiographic result and cardiac index predict ventricular recovery but 50% of those optimally revascularized still required heart replacement therapy.

Hyperventilation in patients who have sustained myocardial infarction after a work injury.

PubMed Central

Rosen, S D; King, J C; Nixon, P G

1994-01-01

Patients who present with acute myocardial infarction after a work injury (AMI-WI) often report symptoms consistent with chronic hyperventilation which date back as far as the work injury itself, rather than to the AMI. The aim of the study was to test the hypothesis that hyperventilation significantly contributes to the symptoms of AMI-WI patients. The prevalence of hyperventilation was assessed by clinical capnography in 12 AMI-WI patients, 20 normal controls, 15 AMI patients whose AMI was conventional and not subsequent to a work injury (AMI-C) and 14 patients with post-traumatic stress disorder (PTSD). End-tidal carbon dioxide partial pressure (P(et)CO2) was measured at rest, after 1 min hyperventilation (FHPT), after recall of the relevant stressor (Think) and when the breathing was felt to be normal (MBIN). P(et)CO2 levels after FHPT were: 29.0 +/- 1.5 (mean +/- SD) mmHg for AMI-WI; 26.7 +/- 1.9 mmHg for PTSD; 32.1 +/- 4.1 mmHg for AMI-C and 33.7 +/- 1.4 mmHg for the controls (P < 0.05 and P < 0.01 for AMI-WI and PTSD, respectively, versus controls). After Think, the levels were 25.8 +/- 1.6 mmHg for AMI-WI, 24.6 +/- 1.4 mmHg for PTSD, 31.2 +/- 4.1 mmHg for AMI-C and 31.2 +/- 1.5 mmHg for normals (P < 0.05 and P < 0.01 for AMI-WI and PTSD, respectively, versus controls). For MBIN, values of P(et)CO2 were 26.8 +/- 1.7 mmHg and 26.7 +/- 1.5 mmHg for AMI-WI and PTSD versus 33.8 +/- 1.2 mmHg for normals, (P < 0.01 for both versus controls).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8207722

Angular dependence of etch rates in the etching of poly-Si and fluorocarbon polymer using SF6, C4F8, and O2 plasmas

NASA Astrophysics Data System (ADS)

Min, Jae-Ho; Lee, Gyeo-Re; Lee, Jin-Kwan; Moon, Sang Heup; Kim, Chang-Koo

2004-05-01

The dependences of etch rates on the angle of ions incident on the substrate surface in four plasma/substrate systems that constitute the advanced Bosch process were investigated using a Faraday cage designed for the accurate control of the ion-incident angle. The four systems, established by combining discharge gases and substrates, were a SF6/poly-Si, a SF6/fluorocarbon polymer, an O2/fluorocarbon polymer, and a C4F8/Si. In the case of SF6/poly-Si, the normalized etch rates (NERs), defined as the etch rates normalized by the rate on the horizontal surface, were higher at all angles than values predicted from the cosine of the ion-incident angle. This characteristic curve shape was independent of changes in process variables including the source power and bias voltage. Contrary to the earlier case, the NERs for the O2/polymer decreased and eventually reached much lower values than the cosine values at angles between 30° and 70° when the source power was increased and the bias voltage was decreased. On the other hand, the NERs for the SF6/polymer showed a weak dependence on the process variables. In the case of C4F8/Si, which is used in the Bosch process for depositing a fluorocarbon layer on the substrate surface, the deposition rate varied with the ion incident angle, showing an S-shaped curve. These characteristic deposition rate curves, which were highly dependent on the process conditions, could be divided into four distinct regions: a Si sputtering region, an ion-suppressed polymer deposition region, an ion-enhanced polymer deposition region, and an ion-free polymer deposition region. Based on the earlier characteristic angular dependences of the etch (or deposition) rates in the individual systems, ideal process conditions for obtaining an anisotropic etch profile in the advanced Bosch process are proposed. .

Efficient recyclable organic solar cells on cellulose nanocrystal substrates with a conducting polymer top electrode deposited by film-transfer lamination

Treesearch

Yinhua Zhou; Talha M. Khan; Jen-Chieh Liu; Canek Fuentes-Hernandez; Jae Won Shim; Ehsan Najafabadi; Jeffrey P. Youngblood; Robert J. Moon; Bernard Kippelen

2014-01-01

We report on efficient solar cells on recyclable cellulose nanocrystal (CNC) substrates with a new device structure wherein polyethylenimine-modified Ag is used as the bottom electron-collecting electrode and high-conductivity poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS, PH1000) is used as the semitransparent top holecollecting electrode. The...

LSPR Tuning from 470 to 800 nm and Improved Stability of Au-Ag Nanoparticles Formed by Gold Deposition and Rebuilding in the Presence of Poly(styrenesulfonate).

PubMed

Cathcart, Nicole; Chen, Jennifer I L; Kitaev, Vladimir

2018-01-16

Stability and precise control over functional properties of metal nanoparticles remain a challenge for the realization of prospective applications. Our described process of shell formation and rebuilding can address both these challenges. Template silver nanoparticles (AgNPs) stabilized by poly(styrenesulfonate) are first transformed with gold deposition, after which the resulting shell rebuilds with the replaced silver. The shell formation and rebuilding are accompanied by large shifts in localized surface plasmon resonance (LSPR) peak position, which enables LSPR tuning in a range from 470 to 800 nm. Furthermore, chemical stability of Au-AgNPs is significantly improved compared to AgNPs due to gold stability. Silver templates of different shapes and sizes were demonstrated to transform to AuAg composite NPs to further extend the accessible LSPR range tuning. Stabilization of template AgNPs with poly(styrenesulfonate), in contrast to commonly used poly(vinylpyrrolidone), was found to be a key factor for shell rebuilding. The developed Au-AgNPs were shown to be advantageous for surface plasmon resonance (SPR) detection and surface-enhanced Raman spectroscopy (SERS) owing to their tunable LSPR and enhanced stability.

Web 2.0 and Self-Reported Student Performance among High School Students in Rural Schools

ERIC Educational Resources Information Center

Cash, Joseph Carl

2010-01-01

This research intends to contribute to the current literature available on the appropriate levels of utilizing Web 2.0 resources in the classroom, therefore, amicably submitting the study's results collaboration of a dynamic theoretical construct for pedagogy in the digital age. Educators must contend with and adapt to cognitive changes within…

Academe Makes for Strange Bedfellows: How Continuing Education and Schools of Management Collide and Cooperate

ERIC Educational Resources Information Center

Halfond, Jay A.; Moore, Thomas E.

2009-01-01

A significant component of continuing education involves teaching management, especially through the array of academic degree programs offered to part-time older students. In fact, the ability to offer management education is critical for the viability of continuing education. Co-existing amicably with its institution's business schools is the…

Overcoming Disciplinary and Institutional Barriers: An Interdisciplinary Course in Economic and Sociological Perspectives on Health Issues

ERIC Educational Resources Information Center

Wade, Bruce H.; Stone, Jack H.

2010-01-01

The authors describe an interdisciplinary course team-taught by an economist and a sociologist. Historically mindful of the less than amicable relationship between these disciplines, these colleagues developed a course that attempted to illuminate the different perspectives of economics and sociology in relation to selected health themes. Such a…

Salt Effects on Surface Structures of Polyelectrolyte Multilayers (PEMs) Investigated by Vibrational Sum Frequency Generation (SFG) Spectroscopy.

PubMed

Ge, Aimin; Matsusaki, Michiya; Qiao, Lin; Akashi, Mitsuru; Ye, Shen

2016-04-26

Sum frequency generation (SFG) vibrational spectroscopy was employed to investigate the surface structures of polyelectrolyte multilayers (PEMs) constructed by sequentially alternating adsorption of poly(diallyldimethylammonium chloride) (PDDA) and poly(styrenesulfonate) (PSS). It was found that the surface structures and surface charge density of the as-deposited PEMs of PDDA/PSS significantly depend on the concentration of sodium chloride (NaCl) present in the polyelectrolyte solutions. Furthermore, it was found that the surface structure of the as-deposited PEMs is in a metastable state and will reach the equilibrium state by diffusion of the polyelectrolyte chain after an aging process, resulting in a polyelectrolyte mixture on the PEM surfaces.

Capacitorless 1T-DRAM on crystallized poly-Si TFT.

PubMed

Kim, Min Soo; Cho, Won Ju

2011-07-01

The single-transistor dynamic random-access memory (1T-DRAM) using a polycrystalline-silicon thin-film transistor (poly-Si TFT) was investigated. A 100-nm amorphous silicon thin film was deposited onto a 200-nm oxidized silicon wafer via low-pressure chemical vapor deposition (LPCVD), and the amorphous silicon layer was crystallized via eximer laser annealing (ELA) with a KrF source of 248 nm wavelength and 400 mJ/cm2 power. The fabricated capacitor less 1T-DRAM on the poly-Si TFT was evaluated via impact ionization and gate-induced drain leakage (GIDL) current programming. The device showed a clear memory margin between the "1" and "0" states, and as the channel length decreased, a floating body effect which induces a kink effect increases with high mobility. Furthermore, the GIDL current programming showed improved memory properties compared to the impact ionization method. Although the sensing margins and retention times in both program methods are commercially insufficient, it was confirmed the feasibility of the application of 1T-DRAM operation to TFTs.

Deposition and Characterization of Hermetic, Biocompatible Thin Film Coatings for Implantable, Electrically Active Devices

NASA Astrophysics Data System (ADS)

Sweitzer, Robyn K.

Retinal prostheses may be used to support patients suffering from Age-related macular degeneration or retinitis pigmentosa. A hermetic encapsulation of the poly(imide )-based prosthesis is important in order to prevent the leakage of water and ions into the electric circuitry embedded in the poly(imide) matrix. The deposition of amorphous aluminum oxide (by sputtering) and diamond like carbon (by pulsed laser ablation and vacuum arc vapor deposition) were studied for the application in retinal prostheses. The resulting thin films were characterized for composition, thickness, adhesion and smoothness by scanning electron microscopy-energy dispersive spectroscopy, atomic force microscopy, profilometry and light microscopy. Electrical stability was evaluated and found to be good. The as-deposited films prevented incursion of salinated fluids into the implant over two (2) three month trials soaking in normal saline at body temperature, Biocompatibility was tested in vivo by implanting coated specimen subretinally in the eye of Yucatan pigs. While amorphous aluminum oxide is more readily deposited with sufficient adhesion quality, biocompatibility studies showed a superior behavior of diamond-like carbon. Amorphous aluminum oxide had more adverse effects and caused more severe damage to the retinal tissue.

From the 2-dimensional unstable polyelectrolyte multilayer to the 3-dimensional stable dry polyelectrolyte capsules.

PubMed

Li, Xiaodong; Zhang, Jianxiang; Hu, Qiaoling; Li, Xiaohui

2011-11-01

Polystyrene-poly(acrylic acid)/poly(allylamine hydrochloride) polyelectrolyte multilayer was found to be instable and apt to reconstruct in the pure water. By depositing polystyrene-poly(acrylic acid)/poly(allylamine hydrochloride) multilayer on the polystyrene-poly(acrylic acid) hybrid CaCO(3) templates, novel polyelectrolyte capsules could be prepared after the removal of the templates. The resultant capsules could keep their three-dimensional (3D) spherical shape after being dried at room temperature, dramatically different from the conventional polyelectrolyte capsules based on nonhybrid templates by layer-by-layer procedure. The instable polyelectrolyte multilayer, hybrid templates, and assembly cycles were demonstrated to be three indispensable factors responsible for the formation of this type of 3D stable capsules. The formation mechanism was also discussed in this study. Copyright © 2011 Elsevier Inc. All rights reserved.

Low-Volatility Model Demonstrates Humidity Affects Environmental Toxin Deposition on Plastics at a Molecular Level.

PubMed

Hankett, Jeanne M; Collin, William R; Yang, Pei; Chen, Zhan; Duhaime, Melissa

2016-02-02

Despite the ever-increasing prevalence of plastic debris and endocrine disrupting toxins in aquatic ecosystems, few studies describe their interactions in freshwater environments. We present a model system to investigate the deposition/desorption behaviors of low-volatility lake ecosystem toxins on microplastics in situ and in real time. Molecular interactions of gas-phase nonylphenols (NPs) with the surfaces of two common plastics, poly(styrene) and poly(ethylene terephthalate), were studied using quartz crystal microbalance and sum frequency generation vibrational spectroscopy. NP point sources were generated under two model environments: plastic on land and plastic on a freshwater surface. We found the headspace above calm water provides an excellent environment for NP deposition and demonstrate significant NP deposition on plastic within minutes at relevant concentrations. Further, NP deposits and orders differently on both plastics under humid versus dry environments. We attributed the unique deposition behaviors to surface energy changes from increased water content during the humid deposition. Lastly, nanograms of NP remained on microplastic surfaces hours after initial NP introduction and agitating conditions, illustrating feasibility for plastic-bound NPs to interact with biota and surrounding matter. Our model studies reveal important interactions between low-volatility environmental toxins and microplastics and hold potential to correlate the environmental fate of endocrine disrupting toxins in the Great Lakes with molecular behaviors.

Fabrication of polymer/cadmium sulfide hybrid solar cells [P3HT:CdS and PCPDTBT:CdS] by spray deposition.

PubMed

Kumar, Neetesh; Dutta, Viresh

2014-11-15

This paper investigates fabrication of surfactant free CdS nanoparticles (NPs) and application in the fabrication of P3HT:CdS and PCPDTBT:CdS bulk-heterojunction hybrid solar cells using high-throughput, large-area, low cost spray deposition technique. Both the hybrid active layers and hole transport layers are deposited by spray technique. The CdS/Poly(3-hexylthiophene-2,5-diyl) (P3HT) and CdS/Poly[2,6-(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] (PCPDTBT) hybrid devices are fabricated by spray deposition process at optimized conditions (i.e. film thickness, spray solution volume, distance between sample and spray nozzle, substrate temperature, etc.). The power conversion efficiency of η=0.6% and 1.02% is obtained for P3HT:CdS and PCPDTBT:CdS hybrid devices, respectively. Spray coating holds significant promise as a technique capable of fabricating large-area, high performance hybrid solar cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Actions Speak Louder than Words: How Do Special Education Administrators Prevent and Resolve Conflict with Families?

ERIC Educational Resources Information Center

Mueller, Tracy Gershwin; Piantoni, Shawn

2013-01-01

Conflict between parents of children with disabilities and school district members has been an ongoing issue for decades. Special education administrators are often designated to address conflict with the intent to find an amicable resolution. Otherwise, conflict can lead to due process hearings that move valuable time and money away from general…

Phthalocyanine polymers

NASA Technical Reports Server (NTRS)

Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

1985-01-01

A method of forming 4,4',4'',4''' -tetraamino phthalocyanines involves reducing 4,4',4'',4''' -tetranitro phthalocyanines, polymerizing the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerizing with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, varnishes, adhesives, and fibers.

Presidential Transitions: It's Not Just the Position, It's the Transition. ACE/Praeger Series on Higher Education

ERIC Educational Resources Information Center

Sanaghan, Patrick H.; Goldstein, Larry; Gaval, Kathleen D.

2007-01-01

A presidential transition has a major impact on the life of an institution. Hundreds of presidential transitions take place annually, and when they are not amicable and carefully orchestrated, they can scar both the institution and the president. This book is designed to provide assistance to presidents, trustees, faculty, and other important…

Delinquency, androgens, and the family: a test of evolutionary neuroandrogenic theory.

PubMed

Ellis, Lee; Das, Shyamal

2013-08-01

There is little doubt that family factors can influence involvement in delinquency, although the full nature and extent of their influences remain unclear. In recent decades, testosterone has been increasingly implicated as a contributor to adolescent offending. The present study sought to determine whether two important types of familial factors--parental socioeconomic status and amicable parent-child relationships--are interacting with testosterone (and possibly other androgens) to affect delinquency. A large sample of North American college students self-reported their involvement in eight categories of delinquency along with self-ratings of various androgen-promoted traits (e.g., muscularity and low-deep voice), parental social status, and the quality of the relationships they had with parents. In both sexes, parent-child relationships and androgens were significantly associated with delinquency but parental social status was not. Factor analysis revealed that the authors' measures of all four categories of variables exhibited strong loadings onto their respective factors. Androgens and amicable parent-child relationships were associated with delinquency but parental social status was not. About one third of the influence of parent-child relationships on delinquency appeared to be attributable to androgens. Findings are discussed from the perspective of the evolutionary neuroandrogenic theory of delinquent and criminal behavior.

PolyDOPA Mussel-Inspired Coating as a Means for Hydroxyapatite Entrapment on Polytetrafluoroethylene Surface for Application in Periodontal Diseases.

PubMed

Nardo, Tiziana; Chiono, Valeria; Ciardelli, Gianluca; Tabrizian, Maryam

2016-02-01

Inert polytetrafluoroethylene (PTFE) membranes for periodontal regeneration suffer from weak osteoconductive properties. In this work, a strategy for hydroxyapatite (HAp) coating on PTFE films through an adhesive layer of self-polymerized 3,4-dihydroxy-DL-phenylalanine (polyDOPA) was developed to improve surface properties. Physico-chemical and morphological analysis demonstrated the deposition of polyDOPA and HAp, with an increase in surface roughness and wettability. A discontinuous coating was present after 14 days in PBS and MC3T3-E1 cells proliferation and adhesion were improved. Results confirmed the potential application of polyDOPA/HAp-coated films for periodontal disease treatments. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrochromic enhancement of latent fingerprints by poly(3,4-ethylenedioxythiophene).

PubMed

Brown, Rachel M; Hillman, A Robert

2012-06-28

Spatially selective electrodeposition of poly-3,4-ethylenedioxythiophene (PEDOT) thin films on metallic surfaces is shown to be an effective means of visualizing latent fingerprints. The technique exploits the fingerprint deposit as an insulating mask, such that electrochemical processes (here, polymer deposition) may only take place on deposit-free areas of the surface between the ridges of the fingerprint deposit; the end result is a negative image of the fingermark. Use of a surfactant (sodium dodecylsulphate, SDS) to solubilise the EDOT monomer allows the use of an aqueous electrolyte. Electrochemical (coulometric) data provide a total assay of deposited material, yielding spatially averaged film thicknesses, which are commensurate with substantive filling of the trenches between fingerprint deposit ridges, but not overfilling to the extent that the ridge detail is covered. This is confirmed by optical microscopy and AFM images, which show continuous polymer deposition within the trenches and good definition at the ridge edges. Stainless steel substrates treated in this manner and transferred to background electrolyte (aqueous sulphuric acid) showed enhanced fingerprints when the contrast between the polymer background and fingerprint deposit was optimised using the electrochromic properties of the PEDOT films. The facility of the method to reveal fingerprints of various ages and subjected to plausible environmental histories was demonstrated. Comparison of this enhancement methodology with commonly used fingerprint enhancement methods (dusting with powder, application of wet powder suspensions and cyanoacrylate fuming) showed promising performance in selected scenarios of practical interest.

Cuticular permeance in relation to wax and cutin development along the growing barley (Hordeum vulgare) leaf.

PubMed

Richardson, Andrew; Wojciechowski, Tobias; Franke, Rochus; Schreiber, Lukas; Kerstiens, Gerhard; Jarvis, Mike; Fricke, Wieland

2007-05-01

The developing leaf three of barley provides an excellent model system for the direct determination of relationships between amounts of waxes and cutin and cuticular permeance. Permeance of the cuticle was assessed via the time-course of uptake of either toluidine blue or (14)C-labelled benzoic acid ([(14)C] BA) along the length of the developing leaf. Toluidine blue uptake only occurred within the region 0-25 mm from the point of leaf insertion (POLI). Resistance--the inverse of permeance--to uptake of [(14)C] BA was determined for four leaf regions and was lowest in the region 10-20 mm above POLI. At 20-30 and 50-60 mm above POLI, it increased by factors of 6 and a further 32, respectively. Above the point of emergence of leaf three from the sheath of leaf two, which was 76-80 mm above POLI, resistance was as high as at 50-60 mm above POLI. GC-FID/MS analyses of wax and cutin showed that: (1) the initial seven fold increase in cuticular resistance coincided with increase in cutin coverage and appearance of waxes; (2) the second, larger and final increase in cuticle resistance was accompanied by an increase in wax coverage, whereas cutin coverage remained unchanged; (3) cutin deposition in barley leaf epidermis occurred in parallel with cell elongation, whereas deposition of significant amounts of wax commenced as cells ceased to elongate.

Surface Modification of Poly(ethylene naphthalate) Substrate and Its Effect on SiNx Film Deposition by Atomic Hydrogen Annealing

NASA Astrophysics Data System (ADS)

Heya, Akira; Matsuo, Naoto

2007-07-01

The surface modification of a plastic substrate by atomic hydrogen annealing (AHA) was investigated for flexible displays. In this method, the plastic substrate was exposed to atomic hydrogen generated by cracking hydrogen molecules on heated tungsten wire. Both surface roughness and contact angle of water droplet on poly(ethylene naphthalate) (PEN) substrates were increased by AHA. The surface of a PEN substrate was reduced by atomic hydrogen without optical transmittance degradation. In addition, the properties of a silicon nitride (SiNx) film deposited on a PEN substrate were changed by AHA, and the adhesion between the SiNx film and the PEN substrate was excellent for application to flexible displays.

Preparation of insulin-containing microcapsules by a layer-by-layer deposition of concanavalin A and glycogen.

PubMed

Sato, Katsuhiko; Kodama, Daisuke; Endo, Yoshihiro; Anzai, Jun-ichi

2009-01-01

The sugar sensitive microcapsules were prepared by a layer-by-layer deposition of concanavalin A (Con A) and glycogen on a calcium carbonate particle containing fluorescein-labeled insulin (F-insulin). The Con A/glycogen multilayer capsules were formed through sugar-lectin interactions by using inner and outer poly(ethyleneimine)/poly(vinyl sulfate) multilayers as supports, while without the supports the microcapsules could not be formed. Fluorescent microscope observations revealed that the capsules thus prepared are spherical in shape with 3-10 microm diameter. The microcapsules released encapsulated F-insulin upon addition of sugars. This is because the added sugars replace glycogen in the binding site of Con A, resulting in the enhanced permeability of the microcapsules to insulin.

Characterization and optimization of polycrystalline Si70%Ge30% for surface micromachined thermopiles in human body applications

NASA Astrophysics Data System (ADS)

Wang, Ziyang; Fiorini, Paolo; Leonov, Vladimir; Van Hoof, Chris

2009-09-01

This paper presents the material characterization methods, characterization results and the optimization scheme for polycrystalline Si70%Ge30% (poly-SiGe) from the perspective of its application in a surface micromachined thermopile. Due to its comparative advantages, such as lower thermal conductivity and ease of processing, over other materials, poly-SiGe is chosen to fabricate a surface micromachined thermopile and eventually a wearable thermoelectric generator (TEG) to be used on a human body. To enable optimal design of advanced thermocouple microstructures, poly-SiGe sample materials prepared by two different techniques, namely low-pressure chemical vapor deposition (LPCVD) with in situ doping and rapid thermal chemical vapor deposition (RTCVD) with ion implantation, have been characterized. Relevant material properties, including electrical resistivity, Seebeck coefficient, thermal conductivity and specific contact resistance, have been reported. For the determination of thermal conductivity, a novel surface-micromachined test structure based on the Seebeck effect is designed, fabricated and measured. Compared to the traditional test structures, it is more advantageous for sample materials with a relatively large Seebeck coefficient, such as poly-SiGe. Based on the characterization results, a further optimization scheme is suggested to allow independent respective optimization of the figure of merit and the specific contact resistance.

Electrical characteristics and thermal stability of n+ polycrystalline- Si/ZrO2/SiO2/Si metal-oxide-semiconductor capacitors

NASA Astrophysics Data System (ADS)

Lim, Kwan-Yong; Park, Dae-Gyu; Cho, Heung-Jae; Kim, Joong-Jung; Yang, Jun-Mo; Ii, Choi-Sang; Yeo, In-Seok; Park, Jin Won

2002-01-01

We have investigated the thermal stability of n+ polycrystalline-Si(poly-Si)/ZrO2(50-140 Å)/SiO2(7 Å)/p-Si metal-oxide-semiconductor (MOS) capacitors via electrical and material characterization. The ZrO2 gate dielectric was prepared by atomic layer chemical vapor deposition using ZrCl4 and H2O vapor. Capacitance-voltage hysteresis as small as ˜12 mV with the flatband voltage of -0.5 V and the interface trap density of ˜5×1010cm-2 eV-1 were attained with activation anneal at 750 °C. A high level of gate leakage current was observed at the activation temperatures over 750 °C and attributed to the interfacial reaction of poly-Si and ZrO2 during the poly-Si deposition and the following high temperature anneal. Because of this, the ZrO2 gate dielectric is incompatible with the conventional poly-Si gate process. In the MOS capacitors having a smaller active area (<50×50 μm2), fortunately, the electrical degradation by further severe silicidation does not occur up to an 800 °C anneal in N2 for 30 min.

Mechanical characterization of poly-SiGe layers for CMOS-MEMS integrated application

NASA Astrophysics Data System (ADS)

Modlinski, Robert; Witvrouw, Ann; Verbist, Agnes; Puers, Robert; De Wolf, Ingrid

2010-01-01

Measuring mechanical properties at the microscale is essential to understand and to fabricate reliable MEMS. In this paper a tensile testing system and matching microscale test samples are presented. The test samples have a dog-bone-like structure. They are designed to mimic standard macro-tensile test samples. The micro-tensile tests are used to characterize 0.9 µm thick polycrystalline silicon germanium (poly-SiGe) films. The poly-SiGe film, that can be considered as a close equivalent to polycrystalline silicon (poly-Si), is studied as a very promising material for use in CMOS/MEMS integration in a single chip due to its low-temperature LPCVD deposition (T < 450 °C). The fabrication process of the poly-SiGe micro-tensile test structure is explained in detail: the design, the processing and post-processing, the testing and finally the results' discussion. The poly-SiGe micro-tensile results are also compared with nanoindentation data obtained on the same poly-SiGe films as well as with results obtained by other research groups.

Electrospraying and Electrospinning of Polymers for Biomedical Applications. Poly(Lactic-Co-Glycolic Acid) and Poly(Ethylene-Co-Vinylacetate). Appendix 2

NASA Technical Reports Server (NTRS)

Stitzel, Joel D.; Bowlin, Gary L.; Mansfield, Kevin; Wnek, Gary E.; Simpson, David G.

2000-01-01

Significant opportunities exist for the processing of polymers (homopolymers and blends) using electric fields. Specific attention is given here to electrospinning, but we note that electroaerosol formation and field-modulated film casting represent additional processing options. Of particular interest is the ability to generate polymer fibers of sub-micron dimensions using electrospinning, down to about 0.05 microns (50 nm), a size range that has been traditionally difficult to access. In our work, poly(lactic-co-glycolic acid), PLA/PGA, poly(lactic acid) PLA, and poly(ethylene-co-vinylacetate) (PEVA) have been deposited from solutions in methylene chloride or chloroform by electrospraying or electrospinning to afford morphologically tailored materials for tissue engineering and related applications. Low solution concentrations tend to favor electrostatic spraying ('electro-aerosolization') while higher concentrations lead to spinning on fibrous mats. Preliminary observations of muscle cell growth on PLA electrospun mats are reported.

Heparin-mimicking multilayer coating on polymeric membrane via LbL assembly of cyclodextrin-based supramolecules.

PubMed

Deng, Jie; Liu, Xinyue; Ma, Lang; Cheng, Chong; Shi, Wenbin; Nie, Chuanxiong; Zhao, Changsheng

2014-12-10

In this study, multifunctional and heparin-mimicking star-shaped supramolecules-deposited 3D porous multilayer films with improved biocompatibility were fabricated via a layer-by-layer (LbL) self-assembly method on polymeric membrane substrates. Star-shaped heparin-mimicking polyanions (including poly(styrenesulfonate-co-sodium acrylate; Star-PSS-AANa) and poly(styrenesulfonate-co-poly(ethylene glycol)methyl ether methacrylate; Star-PSS-EGMA)) and polycations (poly(methyl chloride-quaternized 2-(dimethylamino)ethyl methacrylate; Star-PMeDMA) were first synthesized by atom transfer radical polymerization (ATRP) from β-cyclodextrin (β-CD) based cores. Then assembly of 3D porous multilayers onto polymeric membrane surfaces was carried out by alternating deposition of the polyanions and polycations via electrostatic interaction. The surface morphology and composition, water contact angle, blood activation, and thrombotic potential as well as cell viability for the coated heparin-mimicking films were systematically investigated. The results of surface ATR-FTIR spectra and XPS spectra verified successful deposition of the star-shaped supramolecules onto the biomedical membrane surfaces; scanning electron microscopy (SEM) and atomic force microscopy (AFM) observations revealed that the modified substrate had 3D porous surface morphology, which might have a great biological influence on the biointerface. Furthermore, systematic in vitro investigation of protein adsorption, platelet adhesion, human platelet factor 4 (PF4, indicates platelet activation), activate partial thromboplastin time (APTT), thrombin time (TT), coagulation activation (thrombin-antithrombin III complex (TAT, indicates blood coagulant)), and blood-related complement activation (C3a and C5a, indicates inflammation potential) confirmed that the heparin-mimicking multilayer coated membranes exhibited ultralow blood component activations and excellent hemocompatibility. Meanwhile, after surface coating, endothelial cell viability was also promoted, which indicated that the heparin-mimicking multilayer coating might extend the application fields of polymeric membranes in biomedical fields.

Improved Efficiency of Polymer Solar Cells by means of Coating Hole Transporting Layer as Double Layer Deposition

NASA Astrophysics Data System (ADS)

Chonsut, T.; Kayunkid, N.; Rahong, S.; Rangkasikorn, A.; Wirunchit, S.; Kaewprajak, A.; Kumnorkaew, P.; Nukeaw, J.

2017-09-01

Polymer solar cells is one of the promising technologies that gain tremendous attentions in the field of renewable energy. Optimization of thickness for each layer is an important factor determining the efficiency of the solar cells. In this work, the optimum thickness of Poly(3,4-ethylenedioxythione): poly(styrenesulfonate) (PEDOT:PSS), a famous polymer widely used as hole transporting layer in polymer solar cells, is determined through the analyzing of device’s photovoltaic parameters, e.g. short circuit current density (Jsc), open circuit voltage (Voc), fill factor (FF) as well as power conversion efficiency (PCE). The solar cells were prepared with multilayer of ITO/PEDOT:PSS/PCDTBT:PC70BM/TiOx/Al by rapid convective deposition. In such preparation technique, the thickness of the thin film is controlled by the deposition speed. The faster deposition speed is used, the thicker film is obtained. Furthermore, double layer deposition of PEDOT:PSS was introduced as an approach to improve solar cell efficiency. The results obviously reveal that, with the increase of PEDOT:PSS thickness, the increments of Jsc and FF play the important role to improve PCE from 3.21% to 4.03%. Interestingly, using double layer deposition of PEDOT:PSS shows the ability to enhance the performance of the solar cells to 6.12% under simulated AM 1.5G illumination of 100 mW/cm2.

Magnetron Sputtered Molybdenum Oxide for Application in Polymers Solar Cells

NASA Astrophysics Data System (ADS)

Sendova-Vassileva, M.; Dikov, Hr; Vitanov, P.; Popkirov, G.; Gergova, R.; Grancharov, G.; Gancheva, V.

2016-10-01

Thin films of molybdenum oxide were deposited by radio frequency (RF) magnetron sputtering in Ar from a MoO3 target at different deposition power on glass and silicon substrates. The thickness of the films was determined by profilometer measurements and by ellipsometry. The films were annealed in air at temperatures between 200 and 400°C in air. The optical transmission and reflection spectra were measured. The conductivity of the as deposited and annealed films was determined. The crystal structure was probed by Raman spectroscopy. The oxidation state of the surface was studied by X-ray photoelectron spectroscopy (XPS) spectroscopy. The deposition technique described above was used to experiment with MoOx as a hole transport layer (HTL) in polymer solar cells with bulk hetrojunction active layer, deposited by spin coating. The performance of these layers was compared with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which is the standard material used in this role. The measured current-voltage characteristics of solar cells with the structure glass/ITO/HTL/Poly(3-hexyl)thiophene (P3HT):[6,6]-phenyl-C61- butyric acid methyl ester (PCBM)/Al demonstrate that the studied MoOx layer is a good HTL and leads to comparable characteristics to those with PEDOT:PSS. On the other hand the deposition by magnetron sputtering guarantees reliable and repeatable HTLs.

Mediation as a Leadership Strategy to Deal with Conflict in Schools

ERIC Educational Resources Information Center

Ntho-Ntho, Maitumeleng Albertina; Nieuwenhuis, Frederik Jan

2016-01-01

The concept of mediation is a process that is frequently used in the labour field and is under-developed in a field such as education. Mediation as a strategy to resolve conflict in an amicable way has gained support in various other fields but seems not to be seen as a mainstream solution to resolving conflict in education. This article reports…

Social behavior and aggressive problems of cats.

PubMed

Crowell-Davis, S L; Barry, K; Wolfe, R

1997-05-01

Cats form social groups in which individuals recognize each other, and the cohesiveness of the group is maintained by a variety of amicable behaviors. Agonistic behavior may occur between group members and between group members and nongroup members. Within the domestic environment, agonistic behavior may become a problem when it is directed at housemates or humans. Differential diagnosis and treatment of various problems of aggressive behavior are discussed.

Structural Characterization of Sputtered Silicon Thin Films after Rapid Thermal Annealing for Active-Matrix Organic Light Emitting Diode

NASA Astrophysics Data System (ADS)

de Dieu Mugiraneza, Jean; Miyahira, Tomoyuki; Sakamoto, Akinori; Chen, Yi; Okada, Tatsuya; Noguchi, Takashi; Itoh, Taketsugu

2010-12-01

The microcrystalline phase obtained by adopting a two-step rapid thermal annealing (RTA) process for rf-sputtered silicon films deposited on thermally durable glass was characterized. The optical properties, surface morphology, and internal stress of the annealed Si films are investigated. As the thermally durable glass substrate allows heating of the deposited films at high temperatures, micro-polycrystalline silicon (micro-poly-Si) films of uniform grain size with a smooth surface and a low internal stress could be obtained after annealing at 750 °C. The thermal stress in the Si films was 100 times lower than that found in the films deposited on conventional glass. Uniform grains with an average grain size of 30 nm were observed by transmission electron microscopy (TEM) in the films annealed at 800 °C. These micro-poly-Si films have potential application for fabrication of uniform and reliable thin film transistors (TFTs) for large scale active-matrix organic light emitting diode (AMOLED) displays.

DLVO Approximation Methods for Predicting the Attachment of Silver Nanoparticles to Ceramic Membranes.

PubMed

Mikelonis, Anne M; Youn, Sungmin; Lawler, Desmond F

2016-02-23

This article examines the influence of three common stabilizing agents (citrate, poly(vinylpyrrolidone) (PVP), and branched poly(ethylenimine) (BPEI)) on the attachment affinity of silver nanoparticles to ceramic water filters. Citrate-stabilized silver nanoparticles were found to have the highest attachment affinity (under conditions in which the surface potential was of opposite sign to the filter). This work demonstrates that the interaction between the electrical double layers plays a critical role in the attachment of nanoparticles to flat surfaces and, in particular, that predictions of double-layer interactions are sensitive to boundary condition assumptions (constant charge vs constant potential). The experimental deposition results can be explained when using different boundary condition assumptions for different stabilizing molecules but not when the same assumption was assumed for all three types of particles. The integration of steric interactions can also explain the experimental deposition results. Particle size was demonstrated to have an effect on the predicted deposition for BPEI-stabilized particles but not for PVP.

Conformational Switching in PolyGln Amyloid Fibrils Resulting from a Single Amino Acid Insertion

PubMed Central

Huang, Rick K.; Baxa, Ulrich; Aldrian, Gudrun; Ahmed, Abdullah B.; Wall, Joseph S.; Mizuno, Naoko; Antzutkin, Oleg; Steven, Alasdair C.; Kajava, Andrey V.

2014-01-01

The established correlation between neurodegenerative disorders and intracerebral deposition of polyglutamine aggregates motivates attempts to better understand their fibrillar structure. We designed polyglutamines with a few lysines inserted to overcome the hindrance of extreme insolubility and two D-lysines to limit the lengths of β-strands. One is 33 amino acids long (PolyQKd-33) and the other has one fewer glutamine (PolyQKd-32). Both form well-dispersed fibrils suitable for analysis by electron microscopy. Electron diffraction confirmed cross-β structures in both fibrils. Remarkably, the deletion of just one glutamine residue from the middle of the peptide leads to substantially different amyloid structures. PolyQKd-32 fibrils are consistently 10–20% wider than PolyQKd-33, as measured by negative staining, cryo-electron microscopy, and scanning transmission electron microscopy. Scanning transmission electron microscopy analysis revealed that the PolyQKd-32 fibrils have 50% higher mass-per-length than PolyQKd-33. This distinction can be explained by a superpleated β-structure model for PolyQKd-33 and a model with two β-solenoid protofibrils for PolyQKd-32. These data provide evidence for β-arch-containing structures in polyglutamine fibrils and open future possibilities for structure-based drug design. PMID:24853742

Different copolymer films on ZnFeCo particles: Synthesis and anticorrosion properties

NASA Astrophysics Data System (ADS)

Ozyilmaz, A. Tuncay; Avsar, Busra; Ozyilmaz, Gul; Karahan, İ. Hakkı; Camurcu, Taskin; Colak, Fatma

2014-11-01

Zinc-iron-cobalt (ZnFeCo) particles were electrochemically deposited on carbon steel (CS) electrode applying current of 3 mA with chronopotentiometry technique. ZnFeCo particles had homogenous, smooth with prismatic structure. It was shown that the ZnFeCo particles exhibited important barrier effect on CS substrate. Poly(aniline-co-o-anisidine), poly(aniline-co-pyrrole), poly(aniline-co-N-methylpyrrole) and poly(o-anisidine-co-pyrrole) copolymer films were obtained on CS/ZnFeCo electrode. Evaluation of anticorrosion performance of copolymer coatings in 3.5% NaCl solution was investigated by using AC impedance spectroscopy (EIS) technique, anodic polarization and the Eocp-time curves. Copolymer films exhibited significant physical barrier behavior on ZnFeCo plated carbon steel, in longer exposure time.

Optical properties of poly-HCN and their astronomical applications

NASA Technical Reports Server (NTRS)

Khare, B. N.; Sagan, C.; Thompson, W. R.; Arakawa, E. T.; Meisse, C.; Tuminello, P. S.

1994-01-01

Matthews (1992) has proposed that HCN "polymer" is ubiquitous in the solar system. We apply vacuum deposition and spectroscopic techniques previously used on synthetic organic heteropolymers (tholins), kerogens, and meteoritic organic residues to the measurement of the optical constants of poly-HCN in the wavelength range 0.05-40 micrometers. These measurements allow quantitative comparison with spectrophotometry of organic-rich bodies in the outer solar system. In a specific test of Matthews' hypothesis, poly-HCN fails to match the optical constants of the haze of the Saturnian moon, Titan, in the visible and near-infrared derived from astronomical observations and standard models of the Titan atmosphere. In contrast, a tholin produced from a simulated Titan atmosphere matches within the probable errors. Poly-HCN is much more N-rich than Titan tholin.

Tailored biodegradable triblock copolymer coatings obtained by MAPLE: a parametric study

NASA Astrophysics Data System (ADS)

Brajnicov, S.; Neacsu, P.; Moldovan, A.; Marascu, V.; Bonciu, A.; Ion, R.; Dinca, V.; Cimpean, A.; Dinescu, M.

2017-11-01

Biocompatible and biodegradable coatings with controllable and tailored chemical and physical characteristics (i.e. morphology and roughness) are of great interest in bone related research applications. Within this research direction, in this work, a series of novel biodegradable coatings based on triblock copolymers poly(lactide- co-caprolactone)-block-poly(ethylene-glycol)-block-poly(lactide- co-caprolactone) (PLCL-PEG-PLCL) were obtained by matrix-assisted pulsed laser evaporation (MAPLE) and their morphological characteristics and roughness were modulated by varying target composition and laser fluence. The coatings were used for preliminary in vitro testing with MC3T3-E1 pre-osteoblasts. It was found that for a specific range of fluences, the main functional groups in the MAPLE-deposited thin films, as determined by Fourier transform infrared spectroscopy, are similar to the molecular structures of the initial material. Depending on the deposition parameters, significant changes in morphologies, i.e. material accumulation in the form of droplets, wrinkles, or carpet-like structures were revealed by atomic force microscopy (AFM) and scanning electron microscopy. The optimized coating characteristics were further correlated to MC3T3-E1 pre-osteoblasts response. The ability to control the morphology and to maintain unaltered the chemistry of the deposited material through MAPLE is an important step in creating functional bio-interfaces in the field of biomedical research and tissue engineering.

Macroscopic Electrical Wires from Vapor Deposited Poly(3,4-ethylenedioxythiophene).

PubMed

Koch, Lukas; Polek, Anna; Rudd, Sam; Evans, Drew

2017-01-11

Conducting polymers represent a field of materials innovation that bridges the properties of metals (electrical conduction) with those of traditional polymers (mechanical flexibility). Although electronic properties have been studied, minimal attention is given to their mechanical properties such as tensile strength. This study presents macroscopic wires made from the vapor phase polymerization of poly(3,4-ethylenedioxythiophene) using triblock copolymers as a molecular template. These macroscopic wires are conductive (up to 5 × 10 4 S/m), and possess tensile properties (Young's modulus ∼1.1 GPa; tensile strength ∼90 MPa) comparable to commercially available polymers (Nylon-6 and poly(methyl methacrylate)), without need for nonconductive mechanical fillers.

Parylene C coating for high-performance replica molding.

PubMed

Heyries, Kevin A; Hansen, Carl L

2011-12-07

This paper presents an improvement to the soft lithography fabrication process that uses chemical vapor deposition of poly(chloro-p-xylylene) (parylene C) to protect microfabricated masters and to improve the release of polymer devices following replica molding. Chemical vapor deposition creates nanometre thick conformal coatings of parylene C on silicon wafers having arrays of 30 μm high SU8 pillars with densities ranging from 278 to 10,040 features per mm(2) and aspect ratios (height : width) from 1 : 1 to 6 : 1. A single coating of parylene C was sufficient to permanently promote poly(dimethyl)siloxane (PDMS) mold release and to protect masters for an indefinite number of molding cycles. We also show that the improved release properties of parylene treated masters allow for fabrication with hard polymers, such as poly(urethane), that would otherwise not be compatible with SU8 on silicon masters. Parylene C provides a robust and high performance mold release coating for soft lithography microfabrication that extends the life of microfabricated masters and improves the achievable density and aspect ratio of replicated features.

Synthesis of poly(3-hydroxybutyrate) nanospheres and deposition thereof into porous thin film

NASA Astrophysics Data System (ADS)

Abid, S.; Raza, Z. A.; Rehman, A.

2016-10-01

Polymeric nanostructures have gained importance in medical science as drug delivery carriers due to their biocompatibility and biodegradability. Polyhydroxybutyrate (PHB) is one of the natural biodegradable polymers used to deliver drugs in the form of nano/microcapsules. In this study, solvent evaporation method has been used for the synthesis of PHB nanospheres using poly(vinyl) alcohol (PVA) both as emulsifier and stabilizer. The produced PHB nanospheres were analyzed using dynamic light scattering and scanning electron microscopy. The size of nanospheres decreased whereas the zeta potential increased on increasing the concentration of emulsifier. The PHB nanospheres were then deposited into porous thin film on a glass surface and characterized against bulk PHB film by using atomic force microscopy, contact angle measurement and x-ray diffraction.

Fabrication of Inverted Bulk-Heterojunction Organic Solar Cell with Ultrathin Titanium Oxide Nanosheet as an Electron-Extracting Buffer Layer

NASA Astrophysics Data System (ADS)

Itoh, Eiji; Maruyama, Yasutake; Fukuda, Katsutoshi

2012-02-01

The contributions and deposition conditions of ultrathin titania nanosheet (TN) crystallites were studied in an inverted bulk-heterojunction (BHJ) cell in indium tin oxide (ITO)/titania nanosheet/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic devices. Only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film deposited by the layer-by-layer deposition technique effectively decreased the leakage current and increased both open circuit voltage (VOC) and fill factor (FF), and power conversion efficiency (η) was increased nearly twofold by the insertion of two TN layers. The deposition of additional TN layers caused the reduction in FF, and the abnormal S-shaped curves above VOC for the devices with three and four TN layers were ascribed to the interfacial potential barrier at the ITO/TN interface and the series resistance across the multilayers of TN and PDDA. The performance of the BHJ cell with TN was markedly improved, and the S-shaped curves were eliminated following the the insertion of anatase-phase titanium dioxide between the ITO and TN layers owing to the decrease in the interfacial potential barrier.

Photoswitchable Layer-by-Layer Coatings Based on Photochromic Polynorbornenes Bearing Spiropyran Side Groups.

PubMed

Campos, Paula P; Dunne, Aishling; Delaney, Colm; Moloney, Cara; Moulton, Simon E; Benito-Lopez, Fernando; Ferreira, Marystela; Diamond, Dermot; Florea, Larisa

2018-04-10

Herein, we present the synthesis of linear photochromic norbornene polymers bearing spiropyran side groups (poly(SP-R)) and their assembly into layer-by-layer (LbL) films on glass substrates when converted to poly(MC-R) under UV irradiation. The LbL films were composed of bilayers of poly(allylamine hydrochloride) (PAH) and poly(MC-R), forming (PAH/poly(MC-R)) n coatings. The merocyanine (MC) form presents a significant absorption band in the visible spectral region, which allowed tracking of the LbL deposition process by UV-vis spectroscopy, which showed a linear increase of the characteristic MC absorbance band with increasing number of bilayers. The thickness and morphology of the (PAH/poly(MC-R)) n films were characterized by ellipsometry and scanning electron microscopy, respectively, with a height of ∼27.5 nm for the first bilayer and an overall height of ∼165 nm for the (PAH/poly(MC-R)) 5 multilayer film. Prolonged white light irradiation (22 h) resulted in a gradual decrease of the MC band by 90.4 ± 2.9% relative to the baseline, indicating the potential application of these films as coatings for photocontrolled delivery systems.

Structural and electrical properties of Ag grid/poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) coatings for diode application through advanced printing technology.

PubMed

Duraisamy, Navaneethan; Ponniah, Ganeshthangaraj; Jo, Jeongdai; Choi, Kyung-Hyun

2013-08-01

This paper is focused on printed techniques for the fabrication of hybrid structure of silver (Ag) grid/poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate) (PEDOT:PSS) on polyethylene terepthalate (PET) as a flexible substrate. Ag grid has been printed on PET substrate by using gravure offset printing process, followed by PEDOT:PSS thin film deposition on Ag grid through electrohydrodynamic atomization (EHDA) technique. The important parameters for achieving uniform hybrid structure of Ag grid/PEDOT:PSS through printed techniques have been clearly discussed. Field emission scanning electron microscope studies revealed the uniformity of printed Ag grid with homogeneous deposition of PEDOT:PSS on Ag grid. The optical properties of Ag grid/PEDOT:PSS were measured by UV-visible spectroscopy, which showed nearly 80-82% of transparency in the visible region and it was nearly same as PEDOT:PSS thin film on PET substrate. Current-voltage (I-V) analysis of fabricated hybrid device by using printed Ag grid/PEDOT:PSS as a bottom electrode showed good rectifying behavior with possible interfacial mechanisms. Capacitance-voltage (C-V) analysis was carried over different frequencies. These results suggest that fabrication of hybrid structure through printed techniques will play a significant role in mass production of printed electronic devices for commercial application by using flexible substrate.

Mexican-American War

DTIC Science & Technology

2006-01-01

speedily, but to bring all matters in dispute between this Government and Mexico to an early and amicable adjustment; and in this view I shall be prepared... views , though entertained by but few, have been widely and extensively circulated, not only at home, but have been spread throughout Mexico and the whole...President was referred, fully sustained his views of the character of the wrongs which we had suffered from Mexico , and recommended that another demand

'Partnerships are crucial': an evaluation of the Aboriginal Family Birthing Program in South Australia.

PubMed

Middleton, Philippa; Bubner, Tanya; Glover, Karen; Rumbold, Alice; Weetra, Donna; Scheil, Wendy; Brown, Stephanie

2017-02-01

To evaluate implementation and outcomes of the Aboriginal Family Birthing Program (AFBP), which provides culturally competent antenatal, intrapartum and early postnatal care for Aboriginal families across South Australia (SA). Analysis of births to Aboriginal women in SA 2010-2012; interviews with health professionals and AFBP clients. Around a third of all Aboriginal women giving birth in SA 2010-2012 (n=486) attended AFBP services. AFBP women were more likely to be more socially disadvantaged, have poorer pregnancy health and to have inadequate numbers of antenatal visits than Aboriginal women attending other services. Even with greater social disadvantage and higher clinical complexity, pregnancy outcomes were similar for AFBP and other Aboriginal women. Interviews with 107 health professionals (including 20 Aboriginal Maternal and Infant Care (AMIC) workers) indicated differing levels of commitment to the model, with some lack of clarity about AMIC workers and midwives roles. Interviews with 20 AFBP clients showed they highly valued care from another Aboriginal woman. Despite challenges, the AFBP reaches out to women with the greatest need, providing culturally appropriate, effective care through partnerships. Implications for Public Health: Programs like the AFBP need to be expanded and supported to improve maternal and child health outcomes for Aboriginal families. © 2016 The Authors.

Nitrogen-doped carbon capsules via poly(ionic liquid)-based layer-by-layer assembly.

PubMed

Zhao, Qiang; Fellinger, Tim-Patrick; Antonietti, Markus; Yuan, Jiayin

2012-07-13

Layer-by-layer (LbL) assembly technique is applied for the first time for the preparation of nitrogen-doped carbon capsules. This approach uses colloid silica as template and two polymeric deposition components, that is, poly(ammonium acrylate) and a poly (ionic liquid) poly(3-cyanomethyl-1-vinylimidazolium bromide), which acts as both the carbon precursor and nitrogen source. Nitrogen-doped carbon capsules are prepared successfully by polymer wrapping, subsequent carbonization and template removal. The as-synthesized carbon capsules contain ≈7 wt% of nitrogen and have a structured specific surface area of 423 m(2) g(-1). Their application as supercapacitor has been briefly introduced. This work proves that LbL assembly methodology is available for preparing carbon structures of complex morphology. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Junction-less poly-Ge FinFET and charge-trap NVM fabricated by laser-enabled low thermal budget processes

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

Huang, Wen-Hsien; Shen, Chang-Hong; Wang, Hsing-Hsiang

2016-06-13

A doping-free poly-Ge film as channel material was implemented by CVD-deposited nano-crystalline Ge and visible-light laser crystallization, which behaves as a p-type semiconductor, exhibiting holes concentration of 1.8 × 10{sup 18 }cm{sup −3} and high crystallinity (Raman FWHM ∼ 4.54 cm{sup −1}). The fabricated junctionless 7 nm-poly-Ge FinFET performs at an I{sub on}/I{sub off} ratio over 10{sup 5} and drain-induced barrier lowering of 168 mV/V. Moreover, the fast programming speed of 100 μs–1 ms and reliable retention can be obtained from the junctionless poly-Ge nonvolatile-memory. Such junctionless poly-Ge devices with low thermal budget are compatible with the conventional CMOS technology and are favorable for 3D sequential-layer integrationmore » and flexible electronics.« less

In vivo biocompatibility of three potential intraperitoneal implants.

PubMed

Defrère, Sylvie; Mestagdt, Mélanie; Riva, Raphaël; Krier, Fabrice; Van Langendonckt, Anne; Drion, Pierre; Jérôme, Christine; Evrard, Brigitte; Dehoux, Jean-Paul; Foidart, Jean-Michel; Donnez, Jacques

2011-10-10

The intraperitoneal biocompatibility of PDMS, polyHEMA and pEVA was investigated in rats, rabbits and rhesus monkeys. No inflammation was evidenced by hematological analyses and measurement of inflammatory markers throughout the experiment and by post-mortem examination of the pelvic cavity. After 3 or 6 months, histological analysis revealed fibrous tissue encapsulating PDMS and PEVA implants in all species and polyHEMA implants in rabbits and monkeys. Calcium deposits were observed inside polyHEMA implants. The intraperitoneal biocompatibility of all 3 polymers makes them suitable for the design of drug delivery systems, which may be of great interest for pathologies confined to the pelvic cavity. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hybrid Surface Acoustic Wave- Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films

PubMed Central

Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

2015-01-01

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics. PMID:26478189

Microcontact printing of monodiamond nanoparticles: an effective route to patterned diamond structure fabrication.

PubMed

Zhuang, Hao; Song, Bo; Staedler, Thorsten; Jiang, Xin

2011-10-04

By combining microcontact printing with a nanodiamond seeding technique, a precise micrometer-sized chemical vapor deposition (CVD) diamond pattern have been obtained. On the basis of the guidance of basic theoretical calculations, monodisperse detonation nanodiamonds (DNDs) were chosen as an "ink" material and oxidized poly(dimethylsiloxane) (PDMS) was selected to serve as a stamp because it features a higher interaction energy with the DNDs compared to that of the original PDMS. The adsorption kinetics shows an approximately exponential law with a maximum surface DND density of 3.4 × 10(10) cm(-2) after 20 min. To achieve a high transfer ratio of DNDs from the PDMS stamp to a silicon surface, a thin layer of poly(methyl methacrylate) (PMMA) was spin coated onto the substrates. A microwave plasma chemical vapor deposition system was used to synthesize the CVD diamond on the seeded substrate areas. Precise diamond patterns with a low expansion ratio (3.6%) were successfully prepared after 1.5 h of deposition. Further increases in the deposition time typically lead to a high expansion rate (∼0.8 μm/h). The general pattern shape, however, did not show any significant change. Compared with conventional diamond pattern deposition methods, the technique described here offers the advantages of being simple, inexpensive, damage-free, and highly compatible, rendering it attractive for a broad variety of industrial applications. © 2011 American Chemical Society

Hybrid Surface Acoustic Wave- Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films

NASA Astrophysics Data System (ADS)

Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

2015-10-01

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate (PEDOT:PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PEDOT:PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films’ characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics.

Fabrication of electrically bistable organic semiconducting/ferroelectric blend films by temperature controlled spin coating.

PubMed

Hu, Jinghang; Zhang, Jianchi; Fu, Zongyuan; Weng, Junhui; Chen, Weibo; Ding, Shijin; Jiang, Yulong; Zhu, Guodong

2015-03-25

Organic semiconducting/ferroelectric blend films attracted much attention due to their electrical bistability and rectification properties and thereof the potential in resistive memory devices. During film deposition from the blend solution, spinodal decomposition induced phase separation, resulting in discrete semiconducting phase whose electrical property could be modulated by the continuous ferroelectric phase. However, blend films processed by common spin coating method showed extremely rough surfaces, even comparable to the film thickness, which caused large electrical leakage and thus compromised the resistive switching performance. To improve film roughness and thus increase the productivity of these resistive devices, we developed temperature controlled spin coating technique to carefully adjust the phase separation process. Here we reported our experimental results from the blend films of ferroelectric poly(vinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) and semiconducting poly(3-hexylthiophene) (P3HT). We conducted a series of experiments at various deposition temperatures ranging from 20 to 90 °C. The resulting films were characterized by AFM, SEM, and VPFM to determine their structure and roughness. Film roughness first decreased and then increased with the increase of deposition temperature. Electrical performance was also characterized and obviously improved insulating property was obtained from the films deposited between 50 and 70 °C. By temperature control during film deposition, it is convenient to efficiently fabricate ferroelectric/semiconducting blend films with good electrical bistability.

Monolithic composites of silica aerogels by reactive supercritical deposition of hydroxy-terminated poly(dimethylsiloxane).

PubMed

Sanli, D; Erkey, C

2013-11-27

Monolithic composites of silica aerogels with hydroxyl-terminated poly(dimethylsiloxane) (PDMS(OH)) were developed with a novel reactive supercritical deposition technique. The method involves dissolution of PDMS(OH) in supercritical CO2 (scCO2) and then exposure of the aerogel samples to this single phase mixture of PDMS(OH)-CO2. The demixing pressures of the PDMS(OH)-CO2 binary mixtures determined in this study indicated that PDMS(OH) forms miscible mixtures with CO2 at a wide composition range at easily accessible pressures. Upon supercritical deposition, the polymer molecules were discovered to react with the hydroxyl groups on the silica aerogel surface and form a conformal coating on the surface. The chemical attachment of the polymer molecules on the aerogel surface were verified by prolonged extraction with pure scCO2, simultaneous deposition with superhydrophobic and hydrophilic silica aerogel samples and ATR-FTIR analysis. All of the deposited silica aerogel samples were obtained as monoliths and retained their transparency up to around 30 wt % of mass uptake. PDMS(OH) molecules were found to penetrate all the way to the center of the monoliths and were distributed homogenously throughout the cylindrical aerogel samples. Polymer loadings as high as 75.4 wt % of the aerogel mass could be attained. It was shown that the polymer uptake increases with increasing exposure time, as well as the initial polymer concentration in the vessel.

Hybrid Surface Acoustic Wave-Electrohydrodynamic Atomization (SAW-EHDA) For the Development of Functional Thin Films.

PubMed

Choi, Kyung Hyun; Kim, Hyun Bum; Ali, Kamran; Sajid, Memoon; Uddin Siddiqui, Ghayas; Chang, Dong Eui; Kim, Hyung Chan; Ko, Jeong Beom; Dang, Hyun Woo; Doh, Yang Hoi

2015-10-19

Conventional surface acoustic wave - electrostatic deposition (SAW-ED) technology is struggling to compete with other thin film fabrication technologies because of its limitation in atomizing high density solutions or solutions with strong inter-particle bonding that requires very high frequency (100 MHz) and power. In this study, a hybrid surface acoustic wave - electrohydrodynamic atomization (SAW-EHDA) system has been introduced to overcome this problem by integrating EHDA with SAW to achieve the deposition of different types of conductive inks at lower frequency (19.8 MHZ) and power. Three materials, Poly [2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), Zinc Oxide (ZnO), and Poly(3, 4-ethylenedioxythiophene):Polystyrene Sulfonate ( PSS) have been successfully deposited as thin films through the hybrid SAW-EHDA. The films showed good morphological, chemical, electrical, and optical characteristics. To further evaluate the characteristics of deposited films, a humidity sensor was fabricated with active layer of PSS deposited using the SAW-EHDA system. The response of sensor was outstanding and much better when compared to similar sensors fabricated using other manufacturing techniques. The results of the device and the films' characteristics suggest that the hybrid SAW-EHDA technology has high potential to efficiently produce wide variety of thin films and thus predict its promising future in certain areas of printed electronics.

Microstructure and photovoltaic performance of polycrystalline silicon thin films on temperature-stable ZnO:Al layers

NASA Astrophysics Data System (ADS)

Becker, C.; Ruske, F.; Sontheimer, T.; Gorka, B.; Bloeck, U.; Gall, S.; Rech, B.

2009-10-01

Polycrystalline silicon (poly-Si) thin films have been prepared by electron-beam evaporation and thermal annealing for the development of thin-film solar cells on glass coated with ZnO:Al as a transparent, conductive layer. The poly-Si microstructure and photovoltaic performance were investigated as functions of the deposition temperature by Raman spectroscopy, scanning and transmission electron microscopies including defect analysis, x-ray diffraction, external quantum efficiency, and open circuit measurements. It is found that two temperature regimes can be distinguished: Poly-Si films fabricated by deposition at low temperatures (Tdep<400 °C) and a subsequent thermal solid phase crystallization step exhibit 1-3 μm large, randomly oriented grains, but a quite poor photovoltaic performance. However, silicon films deposited at higher temperatures (Tdep>400 °C) directly in crystalline phase reveal columnar, up to 300 nm big crystals with a strong ⟨110⟩ orientation and much better solar cell parameters. It can be concluded from the results that the electrical quality of the material, reflected by the open circuit voltage of the solar cell, only marginally depends on crystal size and shape but rather on the intragrain properties of the material. The carrier collection, described by the short circuit current of the cell, seems to be positively influenced by preferential ⟨110⟩ orientation of the grains. The correlation between experimental, microstructural, and photovoltaic parameters will be discussed in detail.

FAST TRACK COMMUNICATION: High material efficiency found in electrophoretic deposition of conjugated polymer

NASA Astrophysics Data System (ADS)

Tada, Kazuya; Onoda, Mitsuyoshi

2009-09-01

The material efficiency of electrophoretic deposition of a fluorene-based conjugated polymer, poly[(9,9-dioctyl-2,7-divinylenefluorenylene)-alt-{2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene}] (PDOF-MEHPV), from suspensions with a mixture of acetonitrile and toluene as dispersant is studied. It has been found that the recovery rate of the electrophoretic deposition from a suspension containing 90% of the poor solvent acetonitrile reaches 98%. Although the recovery rate decreases with decreasing acetonitrile content, almost 70% of the polymer can be deposited on the substrates from the suspension containing equivalent volumes of the good and poor solvents by electrophoretic deposition, from which smooth and transparent films suitable for electronic devices are obtained.

Fabrication of PVDF-based blend membrane with a thin hydrophilic deposition layer and a network structure supporting layer via the thermally induced phase separation followed by non-solvent induced phase separation process

NASA Astrophysics Data System (ADS)

Wu, Zhiguo; Cui, Zhenyu; Li, Tianyu; Qin, Shuhao; He, Benqiao; Han, Na; Li, Jianxin

2017-10-01

A simple strategy of thermally induced phase separation followed by non-solvent induced phase separation (TIPS-NIPS) is reported to fabricate poly (vinylidene fluoride) (PVDF)-based blend membrane. The dissolved poly (styrene-co-maleic anhydride) (SMA) in diluent prevents the crystallization of PVDF during the cooling process and deposites on the established PVDF matrix in the later extraction. Compared with traditional coating technique, this one-step TIPS-NIPS method can not only fabricate a supporting layer with an interconnected network structure even via solid-liquid phase separation of TIPS, but also form a uniform SMA skin layer approximately as thin as 200 nm via surface deposition of NIPS. Besides the better hydrophilicity, what's interesting is that the BSA rejection ratio increases from 48% to 94% with the increase of SMA, which indicates that the separation performance has improved. This strategy can be conveniently extended to the creation of firmly thin layer, surface functionalization and structure controllability of the membrane.

Surface passivation investigation on ultra-thin atomic layer deposited aluminum oxide layers for their potential application to form tunnel layer passivated contacts

NASA Astrophysics Data System (ADS)

Xin, Zheng; Ling, Zhi Peng; Nandakumar, Naomi; Kaur, Gurleen; Ke, Cangming; Liao, Baochen; Aberle, Armin G.; Stangl, Rolf

2017-08-01

The surface passivation performance of atomic layer deposited ultra-thin aluminium oxide layers with different thickness in the tunnel layer regime, i.e., ranging from one atomic cycle (∼0.13 nm) to 11 atomic cycles (∼1.5 nm) on n-type silicon wafers is studied. The effect of thickness and thermal activation on passivation performance is investigated with corona-voltage metrology to measure the interface defect density D it(E) and the total interface charge Q tot. Furthermore, the bonding configuration variation of the AlO x films under various post-deposition thermal activation conditions is analyzed by Fourier transform infrared spectroscopy. Additionally, poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate) is used as capping layer on ultra-thin AlO x tunneling layers to further reduce the surface recombination current density to values as low as 42 fA/cm2. This work is a useful reference for using ultra-thin ALD AlO x layers as tunnel layers in order to form hole selective passivated contacts for silicon solar cells.

X-ray photoelectron spectroscopy characterization of composite TiO 2-poly(vinylidenefluoride) films synthesised for applications in pesticide photocatalytic degradation

NASA Astrophysics Data System (ADS)

Losito, I.; Amorisco, A.; Palmisano, F.; Zambonin, P. G.

2005-02-01

X-ray photoelectron spectroscopy (XPS) was adopted for the analytical characterization of composite titanium dioxide-poly(vinylidenefluoride) (TiO 2-PVDF) films developed for applications in the photocatalytic degradation of pollutants. The composites were deposited on glass substrates by casting or spin coating from TiO 2-PVDF suspensions in dimethylformamide (DMF). XPS data on the TiO 2-PVDF surface composition were used to optimize preparation conditions (composition of the TiO 2/PVDF suspension, deposition technique) in terms of titanium dioxide surface amount and film stability. The use of spin-coating deposition and the increase of TiO 2 amount in the DMF suspensions were found to improve the titanium surface content, although high TiO 2/PVDF ratios led to film instability. PVDF-TiO 2 films were also used in preliminary photocatalytic degradation tests on isoproturon, a phenylurea herbicide, under solar UV irradiation; the results were compared to direct photolysis to evaluate the catalytic efficiency of immobilized TiO 2 and the role played by the PVDF film during the degradation process.

Foreign Affairs: Specific Action Plan Needed to Improve Response to Parental Child Abductions

DTIC Science & Technology

2000-03-01

the child or prejudice to interested parties; (3) secure the voluntary return of the child or to bring about an amicable resolution of the issues, and...FOREIGN AFFAIRS Specific Action Plan Needed to Improve Response to Parental Child Abductions DISTRIBUTION STATEMENT A Approved for Public Release...International Parental Child Abduction 17 Page 1 GAO/NSIAD-00-10 Parental Child Abduction Page 2 GAO/NSIAD-00-10 Parental Child Abduction GAP

Perturbation approach for nuclear magnetic resonance solid-state quantum computation

DOE PAGES

Berman, G. P.; Kamenev, D. I.; Tsifrinovich, V. I.

2003-01-01

A dynmore » amics of a nuclear-spin quantum computer with a large number ( L = 1000 ) of qubits is considered using a perturbation approach. Small parameters are introduced and used to compute the error in an implementation of an entanglement between remote qubits, using a sequence of radio-frequency pulses. The error is computed up to the different orders of the perturbation theory and tested using exact numerical solution.« less

Multilayer Thin Film Coatings Capable of Extended Programmable Drug Release: Application to Human Mesenchymal Stem Cell Differentiation

PubMed Central

Hong, Jinkee; Alvarez, Luis M.; Shah, Nisarg J.; Griffith, Linda G.; Kim, Byeong-Su; Char, Kookheon; Hammond, Paula T.

2014-01-01

The promise of cellular therapy lies in healing damaged tissues and organs in vivo as well as generating tissue constructs in vitro for subsequent transplantation. Adult stem cells are ideally suited for cellular therapies due to their pulripotency and the ease with which they can be cultured on novel functionalized substrates. Creating environments to control and successively driving their differentiation toward a lineage of choice is one of the most important challenges of current cell-based engineering strategies. In recent years, a variety of biomedical platforms have been prepared for stem cell cultures, primarily to provide efficient delivery of growth or survival factors to cells and a conducive microenvironment for their growth. Here, we demonstrate that repeating tetralayer structures composed of biocompatible poly(methacrylic acid) (PMAA)/poly(acryl amide) (PAAm)/poly(methacrylic acid) (PMAA)/poly(ethylene oxide)-block-poly(ε-caprolactone) (PEO-b-PCL) micelles arrayed in layer-by-layer (LbL) films can serve as a payload region for dexamethasone (dex) delivery to human mesenchymal stem cells (MSCs). This architecture can induce MSC differentiation into osteoblasts in a dose-dependent manner. The amount of dex loaded in the films is controlled by varying the deposition conditions and the film thickness. Furthermore, release of dex is also controlled by changing the amount of covalent crosslinking of multilayers via thermal treatments. The multilayer architecture including payload and cell-adhesion region introduced here are well suited for extended cell culture thus affording the important and protective effect of both dex release and immobilization. These films may find applications in the local delivery of immobilized therapeutics for biomedical applications, as they can be deposited on a wide range of substrates with different shapes, sizes, and composition. PMID:25485185

Initiated chemical vapor deposition of thermoresponsive poly(N-vinylcaprolactam) thin films for cell sheet engineering.

PubMed

Lee, Bora; Jiao, Alex; Yu, Seungjung; You, Jae Bem; Kim, Deok-Ho; Im, Sung Gap

2013-08-01

Poly(N-vinylcaprolactam) (PNVCL) is a thermoresponsive polymer known to be nontoxic, water soluble and biocompatible. Here, PNVCL homopolymer was successfully synthesized for the first time by use of a one-step vapor-phase process, termed initiated chemical vapor deposition (iCVD). Fourier transform infrared spectroscopy results showed that radical polymerization took place from N-vinylcaprolactam monomers without damaging the functional caprolactam ring. A sharp lower critical solution temperature transition was observed at 31°C from the iCVD poly(N-vinylcaprolactam) (PNVCL) film. The thermoresponsive PNVCL surface exhibited a hydrophilic/hydrophobic alteration with external temperature change, which enabled the thermally modulated attachment and detachment of cells. The conformal coverage of PNVCL film on various substrates with complex topography, including fabrics and nanopatterns, was successfully demonstrated, which can further be utilized to fabricate cell sheets with aligned cell morphology. The advantage of this system is that cells cultured on such thermoresponsive surfaces could be recovered as an intact cell sheet by simply lowering the temperature, eliminating the need for conventional enzymatic treatments. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis of Poly-Silicon Thin Films on Glass Substrate Using Laser Initiated Metal Induced Crystallization of Amorphous Silicon for Space Power Application

NASA Technical Reports Server (NTRS)

Abu-Safe, Husam H.; Naseem, Hameed A.; Brown, William D.

2007-01-01

Poly-silicon thin films on glass substrates are synthesized using laser initiated metal induced crystallization of hydrogenated amorphous silicon films. These films can be used to fabricate solar cells on low cost glass and flexible substrates. The process starts by depositing 200 nm amorphous silicon films on the glass substrates. Following this, 200 nm of sputtered aluminum films were deposited on top of the silicon layers. The samples are irradiated with an argon ion cw laser beam for annealing. Laser power densities ranging from 4 to 9 W/cm2 were used in the annealing process. Each area on the sample is irradiated for a different exposure time. Optical microscopy was used to examine any cracks in the films and loss of adhesion to the substrates. X-Ray diffraction patterns from the initial results indicated the crystallization in the films. Scanning electron microscopy shows dendritic growth. The composition analysis of the crystallized films was conducted using Energy Dispersive x-ray Spectroscopy. The results of poly-silicon films synthesis on space qualified flexible substrates such as Kapton are also presented.

Simple, rapid and, cost-effective fabrication of PDMS electrophoresis microchips using poly(vinyl acetate) as photoresist master.

PubMed

Lobo-Júnior, Eulício O; Gabriel, Ellen F M; Dos Santos, Rodrigo A; de Souza, Fabrício R; Lopes, Wanderson D; Lima, Renato S; Gobbi, Angelo L; Coltro, Wendell K T

2017-01-01

This study describes a simple, rapid, and cost-effective fabrication of PDMS electrophoresis microchips using poly(vinyl acetate) (PVAc) emulsion as photoresist master. High-relief microfluidic structures were defined on poly(vinyl acetate) previously deposited on printed circuit boards surfaces without cleanroom facilities and sophisticated instrumentation. After a UV exposure, channels with heights ranging from 30 to 140 μm were obtained by controlling the emulsion mass deposited on the master surface. The developing stage was performed using water rather than the organic solvents that are applied for conventional masks. The surface morphology was characterized by optical imaging, profilometry, and SEM. Based on the achieved results, the proposed method offers suitable reproducibility for the prototyping of electrophoresis microchips in PDMS. The feasibility of the resulting PDMS electrophoresis chips was successfully demonstrated with the separation of major inorganic cations within 100 s using a contactless conductivity detection system. The separation efficiencies ranged from ca. 67 900 to 125 600 plates/m. Due to the satisfactory performance and simplified instrumentation, we believe this fabrication protocol presents potential to be implemented in any chemical, biochemical, or biological laboratory. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrocatalytic response of poly(cobalt tetraaminophthalocyanine)/multi-walled carbon nanotubes-Nafion modified electrode toward sulfadiazine in urine*

PubMed Central

Hong, Xiao-ping; Zhu, Yan; Zhang, Yan-zhen

2012-01-01

A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(CoIITAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described. This electrode showed a very attractive performance by combining the advantages of CoIITAPc, MWCNTs, and Nafion. Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode, the electrocatalytic activity of poly(CoIITAPc)-coated MWCNTs-Nafion GCE generated greatly improved electrochemical detections toward sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the new modified electrode increased linearly while increasing the concentration of sulfadiazine from 0.5 to 43.5 μmol/L with the detection limit of 0.17 μmol/L. PMID:22661213

Poly-crystalline silicon-oxide films as carrier-selective passivating contacts for c-Si solar cells

NASA Astrophysics Data System (ADS)

Yang, Guangtao; Guo, Peiqing; Procel, Paul; Weeber, Arthur; Isabella, Olindo; Zeman, Miro

2018-05-01

The poly-Si carrier-selective passivating contacts (CSPCs) parasitically absorb a substantial amount of light, especially in the form of free carrier absorption. To minimize these losses, we developed CSPCs based on oxygen-alloyed poly-Si (poly-SiOx) and deployed them in c-Si solar cells. Transmission electron microscopy analysis indicates the presence of nanometer-scale silicon crystals within such poly-SiOx layers. By varying the O content during material deposition, we can manipulate the crystallinity of the poly-SiOx material and its absorption coefficient. Also, depending on the O content, the bandgap of the poly-SiOx material can be widened, making it transparent for longer wavelength light. Thus, we optimized the O alloying, doping, annealing, and hydrogenation conditions. As a result, an extremely high passivation quality for both n-type poly-SiOx (J0 = 3.0 fA/cm2 and iVoc = 740 mV) and p-type poly-SiOx (J0 = 17.0 fA/cm2 and iVoc = 700 mV) is obtained. A fill factor of 83.5% is measured in front/back-contacted solar cells with both polarities made up of poly-SiOx. This indicates that the carrier transport through the junction between poly-SiOx and c-Si is sufficiently efficient. To demonstrate the merit of poly-SiOx layers' high transparency at long wavelengths, they are deployed at the back side of interdigitated back-contacted (IBC) solar cells. A preliminary cell efficiency of 19.7% is obtained with much room for further improvement. Compared to an IBC solar cell with poly-Si CSPCs, a higher internal quantum efficiency at long wavelengths is observed for the IBC solar cell with poly-SiOx CSPCs, thus demonstrating the potential of poly-SiOx in enabling higher JSC.

Surface and Electrochemical Properties of Polymer Brush-Based Redox Poly(Ionic Liquid).

PubMed

Bui-Thi-Tuyet, Van; Trippé-Allard, Gaëlle; Ghilane, Jalal; Randriamahazaka, Hyacinthe

2016-10-26

Redox-active poly(ionic liquid) poly(3-(2-methacryloyloxy ethyl)-1-(N-(ferrocenylmethyl) imidazolium bis(trifluoromethylsulfonyl)imide deposited onto electrode surfaces has been prepared using surface-initiated atom transfer radical polymerization SI-ATRP. The process starts by electrochemical immobilization of initiator layer, and then methacrylate monomer carrying ferrocene and imidazolium units is polymerized in ionic liquid media via SI-ATRP process. The surfaces analyses of the polymer exhibit a well-defined polymer brushlike structure and confirm the presence of ferrocene and ionic moieties within the film. Furthermore, the electrochemical investigations of poly(redox-active ionic liquid) in different media demonstrate that the electron transfer is not restricted by the rate of counterion migration into/out of the polymer. The attractive electrochemical performance of these materials is further demonstrated by performing electrochemical measurement, of poly(ferrocene ionic liquid), in solvent-free electrolyte. The facile synthesis of such highly ordered electroactive materials based ionic liquid could be useful for the fabrication of nanostructured electrode suitable for performing electrochemistry in solvent free electrolyte. We also demonstrate possible applications of the poly(FcIL) as electrochemically reversible surface wettability system and as electrochemical sensor for the catalytic activity toward the oxidation of tyrosine.

The mineral resources of the Borborema Province in Northeastern Brazil and its sedimentary cover: a review

NASA Astrophysics Data System (ADS)

Beurlen, H.

1995-10-01

The geotectonic Borborema Province in Northeast Brazil includes several NE-trending Proterozoic metamorphic belts which amalgamate some small older massifs. It has been known since the Second World War for the skarn-hosted scheelite mineralization and the TaLiBeSn-bearing pegmatites of the Seridó Region. With the drastic drop of the international tungsten prices, three mines were closed in the last decade and only the state-owned Bodó Mine remains working. Since 1961, when Brazilian universities begun to graduate geologists, several dozen mineral deposits were discovered and older prospects were reevaluated. These include the copper deposits of Aurora-State of Ceará (CE) and Serrote da Lage-State of Alagoas (AL), the nickel deposits of S. João do Piauí-State of Piauí (PI), the uranium deposits of Itataia-CE, a dozen gold prospects, the ilmenite deposit of Floresta-State of Pernambuco (PE), the vermiculite mine of Paulistana-PI, and the export quality granite at Bom Jardim-PE and Sumé-Congo-State of Paraíba (PB). In the mostly Cretaceous or Cainozoic sedimentary cover, the discovery includes two important oil and gas fields ((Carmópolis-State of Sergipe (SE) and Mossoró-Macau-State of Rio Grande do Norte (RN)); deposits of sulphur (Castanhal-SE), of KNaMg, salts (Carmópolis-SE, Sto. Antônio-AL), of phosphate (Olinda-PE and João Pessoa-PB), of gypsum (Araripe-PE/CE), of bentonite (Boa Vista-PB) and the Ti placers at Mataraca-PB. In the following pages the current knowledge about these deposits is summarized.

Surface modification of silk fibroin fabric using layer-by-layer polyelectrolyte deposition and heparin immobilization for small-diameter vascular prostheses.

PubMed

Elahi, M Fazley; Guan, Guoping; Wang, Lu; Zhao, Xinzhe; Wang, Fujun; King, Martin W

2015-03-03

There is an urgent need to develop a biologically active implantable small-diameter vascular prosthesis with long-term patency. Silk-fibroin-based small-diameter vascular prosthesis is a promising candidate having higher patency rate; however, the surface modification is indeed required to improve its further hemocompatibility. In this study, silk fibroin fabric was modified by a two-stage process. First, the surface of silk fibroin fabric was coated using a layer-by-layer polyelectrolyte deposition technique by stepwise dipping the silk fibroin fabric into a solution of cationic poly(allylamine hydrochloride) (PAH) and anionic poly(acrylic acid) (PAA) solution. The dipping procedure was repeated to obtain the PAH/PAA multilayers deposited on the silk fibroin fabrics. Second, the polyelectrolyte-deposited silk fibroin fabrics were treated in EDC/NHS-activated low-molecular-weight heparin (LMWH) solution at 4 °C for 24 h, resulting in immobilization of LMWH on the silk fibroin fabrics surface. Scanning electron microscopy, atomic force microscopy, and energy-dispersive X-ray data revealed the accomplishment of LMWH immobilization on the polyelectrolyte-deposited silk fibroin fabric surface. The higher the number of PAH/PAA coating layers on the silk fibroin fabric, the more surface hydrophilicity could be obtained, resulting in a higher fetal bovine serum protein and platelets adhesion resistance properties when tested in vitro. In addition, compared with untreated sample, the surface-modified silk fibroin fabrics showed negligible loss of bursting strength and thus reveal the acceptability of polyelectrolytes deposition and heparin immobilization approach for silk-fibroin-based small-diameter vascular prostheses modification.

Effects of chemical states of carbon on deuterium retention in carbon-containing materials

NASA Astrophysics Data System (ADS)

Oyaidzu, Makoto; Kimura, Hiromi; Nakahata, Toshihiko; Nishikawa, Yusuke; Tokitani, Masayuki; Oya, Yasuhisa; Iwakiri, Hirotomo; Yoshida, Naoaki; Okuno, Kenji

2007-08-01

Deuterium retention behavior in highly oriented pyrolytic graphite (HOPG), poly-crystalline diamond, poly-crystalline SiC, sintered WC, and converted B 4C were investigated to reveal tritium behavior in re-deposition and co-deposition layers. Such layers would contain carbon, when the first wall and/or divertor were made of graphite or carbon-containing materials. Furthermore, the employment of other materials such as tungsten, and first wall conditioning such as boronization would complicate the layers. No different deuterium trapping sites due to carbon from those in HOPG were found in all the samples, where two deuterium trapping processes were observed: hot atom chemical trapping of energetic deuterium by a dangling bond of carbon and thermochemical trapping of thermalized deuterium in a constituent atom vacancy surrounded by carbons. Additionally, the latter reaction could be easily counteracted by or competed with the other deuterium trapping reactions by constituent atoms.

Poly (N-vinyl Carbazole) - Polypyrrole/graphene oxide nanocomposite material on tapered fiber for Q-switched pulse generation

NASA Astrophysics Data System (ADS)

Ahmad, H.; Faruki, M. J.; Jasim, A. A.; Ooi, S. I.; Thambiratnam, K.

2018-02-01

A passively Q-switched fiber laser using a Saturable Absorber (SA) fabricated from a new Poly (N-vinyl Carbazole) - Polypyrrole/Graphene Oxide (PNVC-PPy/GO) nanocomposite material deposited on a tapered fiber is proposed and demonstrated. The PNVC-PPy/GO composition is deposited along a 3 mm length of the 6.5 cm tapered fiber which has a tapered waist of 8 μm. Q-switched pulses are obtained with repetition rates of 25.15-42.7 kHz and pulse widths of 5.74-2.48 μs over a pump power range of 12.8-40.0 mW. A maximum average power of 0.19 mW and pulse energy of 4.43 nJ are also observed. The proposed Q-switched maintains advantages of a simple design and low fabrication cost while at the same time generating high quality Q-switched pulses.

Polymer/metal nanocomposite coating with antimicrobial activity against hospital isolated pathogen

NASA Astrophysics Data System (ADS)

Carvalho, D.; Sousa, T.; Morais, P. V.; Piedade, A. P.

2016-08-01

Nosocomial infections are considered an important problem in healthcare systems and are responsible for a high percentage of morbidity. Among the pathogenic microorganisms responsible for this situation Pseudomonas aeruginosa (P. aeruginosa) is consider one of the most hazardous also due to the fact that antibiotic resistant and multi-resistant organisms begin to emerge as the prevalent strains. In this work the surface of poly(tetrafluoroethylene) (PTFE) was modified by the deposition of PTFE thin films with and without silver. The hydrophobic characteristics of PTFE were attenuated by the co-deposition of PTFE and poly(amide) (PA) with and without silver. The results show that this hospital isolated bacteria is able to degrade PTFE as bulk material as well as some of the developed thin films. However, the combination of both polymer and metal induced the formation of a nanocomposite structure with antimicrobial properties against P. aeruginosa, assessed in three different biotic tests.

21st Century Strategies for Policing Protest: What Major Cities’ Responses to the Occupy Movement Tell U.S. about the Future of Police Response to Public Protest

DTIC Science & Technology

2014-03-01

The Oakland Police Officers Association, responding to what they believed was a laissez - faire approach from Mayor Quan, released an open letter to...little or no opportunity to negotiate an amicable outcome.541 In fairness , a lack of cohesive central leadership on the part of the various Occupy...11 C. POLICE LEADERSHIP ...............................................................................15 D. SOCIOLOGY OF PROTEST

Thermally resistant polymers for fuel tank sealants

NASA Technical Reports Server (NTRS)

Webster, J. A.

1973-01-01

Imide-linked perfluoroalkylene ether polymers, that were developed for the high temperature fuel tank sealant application, are discussed. Modifications of polymer structure and properties were realized through use of a new aromatic dianhydride intermediate containing an ether-linked perfluoroalkylene segment. Tests of thermal, oxidative and hydrolytic stability, fuel resistance, and adhesion are discussed along with tensile strength and elongation results. Efforts to effect a low temperature condensation of amic acid prepolymer to form imide links inside are described.

Elastomer toughened polyimide adhesives

NASA Technical Reports Server (NTRS)

St.clair, A. K.; St.clair, T. L. (Inventor)

1983-01-01

A rubber-toughened addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state, and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride was mixed, and utilizing solvent or mixture of solvents for the reaction.

Mechanisms for Development and Function of Foxp3+ Regulatory T Cells

DTIC Science & Technology

2008-04-04

of the immunological synapse (studies by our group - Thomas et al, 2003); Cholesterol 9 synthesis and thereby the cholesterol amount in CD4 T-cells...precursor of cholesterol synthesis (studies by our group - Brumeanu et al, 2007). At present, it is generally accepted that lipid rafts play a...mice induces a fulminate diabetes within 10-14 days. T-regs and diabetogenic T-cells were isolated on CD4 columns followed by CD25 Ab-magnetic

Inorganic polyphosphate in the microbial world. Emerging roles for a multifaceted biopolymer.

PubMed

Albi, Tomás; Serrano, Aurelio

2016-02-01

Inorganic polyphosphates (polyP) are linear polymers of tens to hundreds orthophosphate residues linked by phosphoanhydride bonds. These fairly abundant biopolymers occur in all extant forms of life, from prokaryotes to mammals, and could have played a relevant role in prebiotic evolution. Since the first identification of polyP deposits as metachromatic or volutin granules in yeasts in the nineteenth century, an increasing number of varied physiological functions have been reported. Due to their "high energy" bonds analogous to those in ATP and their properties as polyanions, polyP serve as microbial phosphagens for a variety of biochemical reactions, as a buffer against alkalis, as a storage of Ca(2+) and as a metal-chelating agent. In addition, recent studies have revealed polyP importance in signaling and regulatory processes, cell viability and proliferation, pathogen virulence, as a structural component and chemical chaperone, and as modulator of microbial stress response. This review summarizes the current status of knowledge and future perspectives of polyP functions and their related enzymes in the microbial world.

Resonant infrared laser deposition of polymer-nanocomposite materials for optoelectronic applications

NASA Astrophysics Data System (ADS)

Park, Hee K.; Schriver, Kenneth E.; Haglund, Richard F.

2011-11-01

Polymers find a number of potentially useful applications in optoelectronic devices. These include both active layers, such as light-emitting polymers and hole-transport layers, and passive layers, such as polymer barrier coatings and light-management films. This paper reports the experimental results for polymer films deposited by resonant infrared matrix-assisted pulsed laser evaporation (RIR-MAPLE) and resonant infrared pulsed laser deposition (RIR-PLD) for commercial optoelectronic device applications. In particular, light-management films, such as anti-reflection coatings, require refractive-index engineering of a material. However, refractive indices of polymers fall within a relatively narrow range, leading to major efforts to develop both low- and high-refractive-index polymers. Polymer nanocomposites can expand the range of refractive indices by incorporating low- or high-refractive-index nanoscale materials. RIR-MAPLE is an excellent technique for depositing polymer-nanocomposite films in multilayer structures, which are essential to light-management coatings. In this paper, we report our efforts to engineer the refractive index of a barrier polymer by combining RIR-MAPLE of nanomaterials (for example, high refractive-index TiO2 nanoparticles) and RIR-PLD of host polymer. In addition, we report on the properties of organic and polymer films deposited by RIR-MAPLE and/or RIR-PLD, such as Alq3 [tris(8-hydroxyquinoline) aluminum] and PEDOT:PSS [poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate)]. Finally, the challenges and potential for commercializing RIR-MAPLE/PLD, such as industrial scale-up issues, are discussed.

Diachronous evolution of volcano-sedimentary basins north of the Congo craton: Insights from U Pb ion microprobe dating of zircons from the Poli, Lom and Yaoundé Groups (Cameroon)

NASA Astrophysics Data System (ADS)

Toteu, Sadrack Félix; Penaye, Joseph; Deloule, Etienne; Van Schmus, William Randall; Tchameni, Rigobert

2006-04-01

Ion microprobe U-Pb dating of zircons from Neoproterozoic volcano-sedimentary sequences in Cameroon north of the Congo craton is presented. For the Poli basin, the depositional age is constrained between 700-665 Ma; detrital sources comprise ca. 920, 830, 780 and 736 Ma magmatic zircons. In the Lom basin, the depositional age is constrained between 613 and 600 Ma, and detrital sources include Archaean to Palaeoproterozoic, late Mesoproterozoic to early Neoproterozoic (1100-950 Ma), and Neoproterozoic (735, 644 and 613 Ma) zircons. The Yaoundé Group is probably younger than 625 Ma, and detrital sources include Palaeoproterozoic and Neoproterozoic zircons. The depositional age of the Mahan metavolcano-sedimentary sequence is post-820 Ma, and detrital sources include late Mesoproterozoic (1070 Ma) and early Neoproterozoic volcanic rocks (824 Ma). The following conclusions can be made from these data. (1) The three basins evolved during the Pan-African event but are significantly different in age and tectonic setting; the Poli is a pre- to syn-collisional basin developed upon, or in the vicinity of young magmatic arcs; the Lom basin is post-collisional and intracontinental and developed on old crust; the tectono-metamorphic evolution of the Yaoundé Group resulted from rapid tectonic burial and subsequent collision between the Congo craton and the Adamawa-Yade block. (2) Late Mesoproterozoic to early Neoproterozoic inheritance reflects the presence of magmatic event(s) of this age in west-central Africa.

Biocompatible Nanocoatings of Fluorinated Polyphosphazenes through Aqueous Assembly

DOE PAGES

Selin, Victor; Albright, Victoria; Ankner, John Francis; ...

2018-02-23

Nonionic fluorinated polyphosphazenes, such as poly[bis(trifluoroethoxy)phosphazene] (PTFEP), display superb biocompatibility, yet their deposition to surfaces has been limited to solution casting from organic solvents or thermal molding. Here in this paper, hydrophobic coatings of fluorinated polyphosphazenes are demonstrated through controlled deposition of ionic fluorinated polyphosphazenes (iFPs) from aqueous solutions using the layer-by-layer (LbL) technique. Specifically, the assemblies included poly[(carboxylatophenoxy)(trifluoroethoxy)phosphazenes] with varied content of fluorine atoms as iFPs (or poly[bis(carboxyphenoxy)phosphazene] (PCPP) as a control nonfluorinated polyphosphazene) and a variety of polycations. Hydrophobic interactions largely contributed to the formation of LbL films of iFPs with polycations, leading to linear growth and extremelymore » low water uptake. Hydrophobicity-enhanced ionic pairing within iFP/BPEI assemblies gave rise to large-amplitude oscillations in surface wettability as a function of capping layer, which were the largest for the most fluorinated iFP, while control PCPP/polycation systems remained hydrophilic regardless of the film top layer. Neutron reflectometry (NR) studies indicated superior layering and persistence of such layering in salt solution for iFP/BPEI films as compared to control PCPP/polycation systems. Hydrophobicity of iFP-capped LbL coatings could be further enhanced by using a highly porous polyester surgical felt rather than planar substrates for film deposition. Importantly, iFP/polycation coatings displayed biocompatibility which was similar to or superior to that of solution-cast coatings of a clinically validated material (PTFEP), as demonstrated by the hemolysis of the whole blood and protein adsorption studies.« less

Biocompatible Nanocoatings of Fluorinated Polyphosphazenes through Aqueous Assembly

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

Selin, Victor; Albright, Victoria; Ankner, John Francis

Nonionic fluorinated polyphosphazenes, such as poly[bis(trifluoroethoxy)phosphazene] (PTFEP), display superb biocompatibility, yet their deposition to surfaces has been limited to solution casting from organic solvents or thermal molding. Here in this paper, hydrophobic coatings of fluorinated polyphosphazenes are demonstrated through controlled deposition of ionic fluorinated polyphosphazenes (iFPs) from aqueous solutions using the layer-by-layer (LbL) technique. Specifically, the assemblies included poly[(carboxylatophenoxy)(trifluoroethoxy)phosphazenes] with varied content of fluorine atoms as iFPs (or poly[bis(carboxyphenoxy)phosphazene] (PCPP) as a control nonfluorinated polyphosphazene) and a variety of polycations. Hydrophobic interactions largely contributed to the formation of LbL films of iFPs with polycations, leading to linear growth and extremelymore » low water uptake. Hydrophobicity-enhanced ionic pairing within iFP/BPEI assemblies gave rise to large-amplitude oscillations in surface wettability as a function of capping layer, which were the largest for the most fluorinated iFP, while control PCPP/polycation systems remained hydrophilic regardless of the film top layer. Neutron reflectometry (NR) studies indicated superior layering and persistence of such layering in salt solution for iFP/BPEI films as compared to control PCPP/polycation systems. Hydrophobicity of iFP-capped LbL coatings could be further enhanced by using a highly porous polyester surgical felt rather than planar substrates for film deposition. Importantly, iFP/polycation coatings displayed biocompatibility which was similar to or superior to that of solution-cast coatings of a clinically validated material (PTFEP), as demonstrated by the hemolysis of the whole blood and protein adsorption studies.« less

Thermo-Mechanical Properties of Alumina Films Created Using the Atomic Layer Deposition Technique

DTIC Science & Technology

2010-01-01

Transducers (iMINT), University of Colorado, Boulder, CO 80309, USA a r t i c l e i n f o Article history : Received 8 March 2010 Received in revised...technology [68], the microcantilever method is not well suited for the MUMPs technology [70], because the nominal radius of curvature of polySi/SiO2...polySi compos- ite structures is roughly 43 (m−1). That is, the tip of similar MUMPs beams will contact the substrate for lengths >200m. The curvature of

Polycrystalline silicon thin-film transistors on quartz fiber

NASA Astrophysics Data System (ADS)

Sugawara, Yuta; Uraoka, Yukiharu; Yano, Hiroshi; Hatayama, Tomoaki; Fuyuki, Takashi; Nakamura, Toshihiro; Toda, Sadayuki; Koaizawa, Hisashi; Mimura, Akio; Suzuki, Kenkichi

2007-11-01

We demonstrate the fabrication of polycrystalline silicon (poly-Si) thin-film transistors (TFTs) on a thin quartz fiber for the first time. The poly-Si used in the active layer of the TFTs was prepared by excimer laser annealing of an amorphous Si thin film deposited on the fiber. Top-gated TFTs were fabricated on the fiber, and a field effect mobility of 10cm2/Vs was obtained. The proposed TFTs on a thin quartz fiber, named fiber TFTs, have potential application in microelectronic devices using TFTs fabricated on one-dimensional substrates.

Improved di-p-xylylene polymer and apparatus and method for making the same

DOEpatents

Jahn, R.K.; Liepins, R.

Solid di-para-xylyene dimer is sublimed in a sublimation furnace at approximately 100 to 200/sup 0/C and subsequently conducted to a pyrolysis furnace where it is pyrolyzed to the diradical p-xylylene monomer while in the vapor state at approximately 600 degrees C. The diradical monomer is then introduced into a deposition chamber for deposition onto a suitable substrate. The deposition chamber includes electrodes for producing a low pressure plasma through which the diradical monomer passes prior to deposition. The interaction of the diradical monomer with the low pressure plasma results in the formation of poly-p-xylyene film which is exceptionally hard and thermally stable.

An Analysis of Hole Trapping at Grain Boundary or Poly-Si Floating-Body MOSFET.

PubMed

Jang, Taejin; Baek, Myung-Hyun; Kim, Hyungjin; Park, Byung-Gook

2018-09-01

In this paper, we demonstrate the characteristics of the floating body effect of poly-silicon with grain boundary by SENTAURUS™ TCAD simulation. As drain voltage increases, impact ionization occurs at the drain-channel junction. And these holes created by impact ionization are deposited on the bottom of the body to change the threshold voltage. This feature, the kink effect, is also observed in fully depleted silicon on insulator because grain boundary of the poly-silicon serve as a storage to trap the holes. We simulate the transfer curve depending on the density and position of the grain boundary. The trap density of the grain boundary affects the device characteristics significantly. However similar properties appear except where the grain boundary is located on the drain side.

Late Administration of a Palladium Lipoic Acid Complex (POLY-MVA) Modifies Cardiac Mitochondria but Not Functional or Structural Manifestations of Radiation-Induced Heart Disease in a Rat Model

PubMed Central

Sridharan, Vijayalakshmi; Seawright, John W.; Antonawich, Francis J.; Garnett, Merrill; Cao, Maohua; Singh, Preeti; Boerma, Marjan

2017-01-01

Exposure of the heart to ionizing radiation can cause adverse myocardial remodeling. In small animal models, local heart irradiation causes persistent alterations in cardiac mitochondrial function and swelling. POLY-MVA is a dietary supplement that contains a palladium lipoic acid complex that targets mitochondrial complex I and has been demonstrated to have greater redox potential than lipoic acid alone. POLY-MVA improves mitochondrial function and anti-oxidant enzyme activity in the aged rat heart. In this study, we tested whether POLY-MVA can mitigate cardiac effects of ionizing radiation. Adult male rats were exposed to local heart X rays with a daily dose of 9 Gy for 5 consecutive days. Eighteen weeks after irradiation, POLY-MVA was administered orally at 1 ml/kg bodyweight per day during weekdays, for 6 weeks. Alterations in cardiac function as measured with echocardiography coincided with enhanced mitochondrial swelling, a reduction in mitochondrial expression of complex II, manifestations of adverse remodeling such as a reduction in myocardial microvessel density and an increase in collagen deposition and mast cell numbers. POLY-MVA enhanced left ventricular expression of superoxide dismutase 2, but only in sham-irradiated animals. In irradiated animals, POLY-MVA caused a reduction in markers of inflammatory infiltration, CD2 and CD68. Moreover, POLY-MVA mitigated the effects of radiation on mitochondria. Nonetheless, POLY-MVA did not mitigate adverse cardiac remodeling, suggesting that this tissue remodeling may not be alleviated by altering cardiac mitochondria alone. However, we cannot exclude the possibility that an earlier onset of POLY-MVA administration may have more profound effects on radiation-induced cardiac remodeling. PMID:28231026

Investigations on the effects of electrode materials on the device characteristics of ferroelectric memory thin film transistors fabricated on flexible substrates

NASA Astrophysics Data System (ADS)

Yang, Ji-Hee; Yun, Da-Jeong; Seo, Gi-Ho; Kim, Seong-Min; Yoon, Myung-Han; Yoon, Sung-Min

2018-03-01

For flexible memory device applications, we propose memory thin-film transistors using an organic ferroelectric poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] gate insulator and an amorphous In-Ga-Zn-O (a-IGZO) active channel. The effects of electrode materials and their deposition methods on the characteristics of memory devices exploiting the ferroelectric field effect were investigated for the proposed ferroelectric memory thin-film transistors (Fe-MTFTs) at flat and bending states. It was found that the plasma-induced sputtering deposition and mechanical brittleness of the indium-tin oxide (ITO) markedly degraded the ferroelectric-field-effect-driven memory window and bending characteristics of the Fe-MTFTs. The replacement of ITO electrodes with metal aluminum (Al) electrodes prepared by plasma-free thermal evaporation greatly enhanced the memory device characteristics even under bending conditions owing to their mechanical ductility. Furthermore, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) was introduced to achieve robust bending performance under extreme mechanical stress. The Fe-MTFTs using PEDOT:PSS source/drain electrodes were successfully fabricated and showed the potential for use as flexible memory devices. The suitable choice of electrode materials employed for the Fe-MTFTs is concluded to be one of the most important control parameters for highly functional flexible Fe-MTFTs.

Vapor-phase deposition of regioregular and oriented poly(3-hexylthiophene) structures and novel nanostructured composites of interpenetrating poly(3-hexylthiophene) and polyaniline exhibiting full-color wavelength (400-1000 nm) photoluminescence

NASA Astrophysics Data System (ADS)

Biswas, A.; Bayer, I. S.; Karulkar, P. C.; Tripathi, A.; Avasthi, D. K.

2007-10-01

A promising solvent-free technique of electron-beam-assisted vapor-phase codeposition method is presented which allows uniform blending of different conjugated and nonconjugated polymers at the nanoscale. The technique allows direct incorporation of regioregular poly(3-hexylthiophene) (P3HT) polymer with different structural orientations into conventional and semiconducting polymers without fractionation or degradation of P3HT while maintaining the nanoscale morphology of deposited organic films. The results of fabricated novel nanostructured organic composites (˜100-200nm) comprising regioregular and oriented P3HT and different conjugated and nonconjugated polymers including selective assembly of P3HT nanonodules into a copolymer template are presented. We show a typical example of blending of P3HT and polyaniline (PANI) that formed a unique nanoscale morphology comprising interpenetrating networks of different shapes and sizes of nanospherulites (˜100nm) of P3HT in PANI. The so fabricated nanocomposites (˜200nm) exhibited remarkable broadband photoluminescence features covering the entire blue, green, and red wavelength regions between 400 and 1000nm. Such organic nanocomposites might be useful for flexible full-color screen flat panel displays and organic white-light solid-state lighting applications.

Ionically Paired Layer-by-Layer Hydrogels: Water and Polyelectrolyte Uptake Controlled by Deposition Time

DOE PAGES

Selin, Victor; Ankner, John Francis; Sukhishvili, Svetlana

2018-01-11

Despite intense recent interest in weakly bound nonlinear (“exponential”) multilayers, the underlying structure-property relationships of these films are still poorly understood. This study explores the effect of time used for deposition of individual layers of nonlinearly growing layer-by-layer (LbL) films composed of poly(methacrylic acid) (PMAA) and quaternized poly-2-(dimethylamino)ethyl methacrylate (QPC) on film internal structure, swelling, and stability in salt solution, as well as the rate of penetration of invading polyelectrolyte chains. Thicknesses of dry and swollen films were measured by spectroscopic ellipsometry, film internal structure—by neutron reflectometry (NR), and degree of PMAA ionization—by Fourier-transform infrared spectroscopy (FTIR). The results suggestmore » that longer deposition times resulted in thicker films with higher degrees of swelling (up to swelling ratio as high as 4 compared to dry film thickness) and stronger film intermixing. The stronger intermixed films were more swollen in water, exhibited lower stability in salt solutions, and supported a faster penetration rate of invading polyelectrolyte chains. These results can be useful in designing polyelectrolyte nanoassemblies for biomedical applications, such as drug delivery coatings for medical implants or tissue engineering matrices.« less

Ionically Paired Layer-by-Layer Hydrogels: Water and Polyelectrolyte Uptake Controlled by Deposition Time

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

Selin, Victor; Ankner, John Francis; Sukhishvili, Svetlana

Despite intense recent interest in weakly bound nonlinear (“exponential”) multilayers, the underlying structure-property relationships of these films are still poorly understood. This study explores the effect of time used for deposition of individual layers of nonlinearly growing layer-by-layer (LbL) films composed of poly(methacrylic acid) (PMAA) and quaternized poly-2-(dimethylamino)ethyl methacrylate (QPC) on film internal structure, swelling, and stability in salt solution, as well as the rate of penetration of invading polyelectrolyte chains. Thicknesses of dry and swollen films were measured by spectroscopic ellipsometry, film internal structure—by neutron reflectometry (NR), and degree of PMAA ionization—by Fourier-transform infrared spectroscopy (FTIR). The results suggestmore » that longer deposition times resulted in thicker films with higher degrees of swelling (up to swelling ratio as high as 4 compared to dry film thickness) and stronger film intermixing. The stronger intermixed films were more swollen in water, exhibited lower stability in salt solutions, and supported a faster penetration rate of invading polyelectrolyte chains. These results can be useful in designing polyelectrolyte nanoassemblies for biomedical applications, such as drug delivery coatings for medical implants or tissue engineering matrices.« less

Limits of ZnO Electrodeposition in Mesoporous Tin Doped Indium Oxide Films in View of Application in Dye-Sensitized Solar Cells

PubMed Central

Dunkel, Christian; von Graberg, Till; Smarsly, Bernd M.; Oekermann, Torsten; Wark, Michael

2014-01-01

Well-ordered 3D mesoporous indium tin oxide (ITO) films obtained by a templated sol-gel route are discussed as conductive porous current collectors. This paper explores the use of such films modified by electrochemical deposition of zinc oxide (ZnO) on the pore walls to improve the electron transport in dye-sensitized solar cells (DSSCs). Mesoporous ITO film were dip-coated with pore sizes of 20–25 nm and 40–45 nm employing novel poly(isobutylene)-b-poly(ethylene oxide) block copolymers as structure-directors. After electrochemical deposition of ZnO and sensitization with the indoline dye D149 the films were tested as photoanodes in DSSCs. Short ZnO deposition times led to strong back reaction of photogenerated electrons from non-covered ITO to the electrolyte. ITO films with larger pores enabled longer ZnO deposition times before pore blocking occurred, resulting in higher efficiencies, which could be further increased by using thicker ITO films consisting of five layers, but were still lower compared to nanoporous ZnO films electrodeposited on flat ITO. The major factors that currently limit the application are the still low thickness of the mesoporous ITO films, too small pore sizes and non-ideal geometries that do not allow obtaining full coverage of the ITO surface with ZnO before pore blocking occurs. PMID:28788618

Room Temperature Sensing Achieved by GaAs Nanowires and oCVD Polymer Coating.

PubMed

Wang, Xiaoxue; Ermez, Sema; Goktas, Hilal; Gradečak, Silvija; Gleason, Karen

2017-06-01

Novel structures comprised of GaAs nanowire arrays conformally coated with conducting polymers (poly(3,4-ethylenedioxythiophene) (PEDOT) or poly(3,4-ethylenedioxythiophene-co-3-thiophene acetic acid) display both sensitivity and selectivity to a variety of volatile organic chemicals. A key feature is room temperature operation, so that neither a heater nor the power it would consume, is required. It is a distinct difference from traditional metal oxide sensors, which typically require elevated operational temperature. The GaAs nanowires are prepared directly via self-seeded metal-organic chemical deposition, and conducting polymers are deposited on GaAs nanowires using oxidative chemical vapor deposition (oCVD). The range of thickness for the oCVD layer is between 100 and 200 nm, which is controlled by changing the deposition time. X-ray diffraction analysis indicates an edge-on alignment of the crystalline structure of the PEDOT coating layer on GaAs nanowires. In addition, the positive correlation between the improvement of sensitivity and the increasing nanowire density is demonstrated. Furthermore, the effect of different oCVD coating materials is studied. The sensing mechanism is also discussed with studies considering both nanowire density and polymer types. Overall, the novel structure exhibits good sensitivity and selectivity in gas sensing, and provides a promising platform for future sensor design. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solvent-free thermoplastic-poly(dimethylsiloxane) bonding mediated by UV irradiation followed by gas-phase chemical deposition of an adhesion linker

NASA Astrophysics Data System (ADS)

Ahn, S. Y.; Lee, N. Y.

2015-07-01

Here, we introduce a solvent-free strategy for bonding various thermoplastic substrates with poly(dimethylsiloxane) (PDMS) using ultraviolet (UV) irradiation followed by the gas-phase chemical deposition of aminosilane on the UV-irradiated thermoplastic substrates. The thermoplastic substrates were first irradiated with UV for surface hydrophilic treatment and were then grafted with vacuum-evaporated aminosilane, where the alkoxysilane side reacted with the oxidized surface of the thermoplastic substrate. Next, the amine-terminated thermoplastic substrates were treated with corona discharge to oxidize the surface and were bonded with PDMS, which was also oxidized via corona discharge. The two substrates were then hermetically sealed and pressed under atmospheric pressure for 30 min at 60 °C. This process enabled the formation of a robust siloxane bond (Si-O-Si) between the thermoplastic substrate and PDMS under relatively mild conditions using an inexpensive and commercially available UV lamp and Tesla coil. Various thermoplastic substrates were examined for bonding with PDMS, including poly(methylmethacrylate) (PMMA), polycarbonate (PC), poly(ethyleneterephthalate) (PET) and polystyrene (PS). Surface characterizations were performed by measuring the contact angle and performing x-ray photoelectron spectroscopy analysis, and the bond strength was analyzed by conducting various mechanical force measurements such as pull, delamination, leak and burst tests. The average bond strengths for the PMMA-PDMS, PC-PDMS, PET-PDMS and PS-PDMS assemblies were measured at 823.6, 379.3, 291.2 and 229.0 kPa, respectively, confirming the highly reliable performance of the introduced bonding strategy.

In vitro evaluation of poly(ethylene glycol)-block-poly(ɛ-caprolactone) methyl ether copolymer coating effects on cells adhesion and proliferation

NASA Astrophysics Data System (ADS)

Rusen, Laurentiu; Neacsu, Patricia; Cimpean, Anisoara; Valentin, Ion; Brajnicov, Simona; Dumitrescu, L. N.; Banita, Janina; Dinca, Valentina; Dinescu, Maria

2016-06-01

Understanding and controlling natural and synthetic biointerfaces is known to be the key to a wide variety of application within cell culture and tissue engineering field. As both material characteristics and methods are important in tailoring biointerfaces characteristics, in this work we explore the feasibility of using Matrix Assisted Pulsed Laser Evaporation technique for obtaining synthetic copolymeric biocoatings (i.e. poly(ethylene glycol)-block-poly(ɛ-caprolactone) methyl ether) for evaluating in vitro Vero and MC3T3-E1 pre-osteoblasts cell response. Characterization and evaluation of the coated substrates were carried out using different techniques. The Fourier transform infrared spectroscopy data demonstrated that the main functional groups in the MAPLE-deposited films remained intact. Atomic Force Microscopy images showed the coatings to be continuous, with the surface roughness depending on the deposition parameters. Moreover, the behaviour of the coatings in medium mimicking the pH and temperature of the human body was studied and corelated to degradation. Spectro-ellipsometry (SE) and AFM measurements revealed the degradation trend during immersion time by the changes in coating thickness and roughness. In vitro biocompatibility was studied by indirect contact tests on Vero cells in accordance with ISO 10993-5/2009. The results obtained in terms of cell morphology (phase contrast microscopy) and cytotoxicity (LDH and MTT assays) proved biocompatibility. Furthermore, direct contact assays on MC3T3-E1 pre-osteoblasts demonstrated the capacity of all analyzed specimens to support cell adhesion, normal cellular morphology and growth.

BMP7 Induces Dormancy of Prostatic Tumor Stem Cell in Bone

DTIC Science & Technology

2012-10-01

the upper back of nude mice. Recombinant human BMP7 was peritumorally injected daily after implantation. Tumor growth was monitored weekly by...of BMP7 was administrated daily through i.v. after intracardiac injection of CSCs from PC3mm or C4-2B cells to the mice. As shown in Figure 5A...mice, and then BMP7 was administrated daily . BLI of representative mice in each group six weeks after implantation (A). Normalized BLI signals

Unification Strategy for North and South Korea: The Most Prudent U.S. Policy Option to Solve the North Korean Nuclear Crisis

DTIC Science & Technology

2004-09-01

the 1882 expedition, hoping to not repeat the mistakes of the Low mission, was much more conciliatory toward King Kojong. The result was the U.S...diplomatic in its approach. In a letter to King Kojong before his mission, Shufeldt expressed his wish to bring about an “amicable intercourse” between...regard, Korea and Vietnam were China’s most reliable traditional allies. In exchange, China promised to defend the domains of neighboring kings who

Poly(3,4-ethylenedioxythiophene)-Poly(styrenesulfonate) Interlayer Insertion Enables Organic Quaternary Memory.

PubMed

Cheng, Xue-Feng; Hou, Xiang; Qian, Wen-Hu; He, Jing-Hui; Xu, Qing-Feng; Li, Hua; Li, Na-Jun; Chen, Dong-Yun; Lu, Jian-Mei

2017-08-23

Herein, for the first time, quaternary resistive memory based on an organic molecule is achieved via surface engineering. A layer of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT-PSS) was inserted between the indium tin oxide (ITO) electrode and the organic layer (squaraine, SA-Bu) to form an ITO/PEDOT-PSS/SA-Bu/Al architecture. The modified resistive random-access memory (RRAM) devices achieve quaternary memory switching with the highest yield (∼41%) to date. Surface morphology, crystallinity, and mosaicity of the deposited organic grains are greatly improved after insertion of a PEDOT-PSS interlayer, which provides better contacts at the grain boundaries as well as the electrode/active layer interface. The PEDOT-PSS interlayer also reduces the hole injection barrier from the electrode to the active layer. Thus, the threshold voltage of each switching is greatly reduced, allowing for more quaternary switching in a certain voltage window. Our results provide a simple yet powerful strategy as an alternative to molecular design to achieve organic quaternary resistive memory.

Electrodeposition of copper on a Pt(111) electrode in sulfuric acid containing poly(ethylene glycol) and chloride ions as probed by in situ STM.

PubMed

Fu, YunLin; Pao, Te; Chen, Sih-Zih; Yau, ShuehLin; Dow, Wei-Ping; Lee, Yuh-Lang

2012-07-03

This study employed real-time in situ STM imaging to examine the adsorption of PEG molecules on Pt(111) modified by a monolayer of copper adatoms and the subsequent bulk Cu deposition in 1 M H(2)SO(4) + 1 mM CuSO(4)+ 1 mM KCl + 88 μM PEG. At the end of Cu underpotential deposition (~0.35 V vs Ag/AgCl), a highly ordered Pt(111)-(√3 × √7)-Cu + HSO(4)(-) structure was observed in 1 M H(2)SO(4) + 1 mM CuSO(4). This adlattice restructured upon the introduction of poly(ethylene glycol) (PEG, molecular weight 200) and chloride anions. At the onset potential for bulk Cu deposition (~0 V), a Pt(111)-(√3 × √3)R30°-Cu + Cl(-) structure was imaged with a tunneling current of 0.5 nA and a bias voltage of 100 mV. Lowering the tunneling current to 0.2 nA yielded a (4 × 4) structure, presumably because of adsorbed PEG200 molecules. The subsequent nucleation and deposition processes of Cu in solution containing PEG and Cl(-) were examined, revealing the nucleation of 2- to 3-nm-wide CuCl clusters on an atomically smooth Pt(111) surface at overpotentials of less than 50 mV. With larger overpotential (η > 150 mV), Cu deposition seemed to bypass the production of CuCl species, leading to layered Cu deposition, starting preferentially at step defects, followed by lateral growth to cover the entire Pt electrode surface. These processes were observed with both PEG200 and 4000, although the former tended to produce more CuCl nanoclusters. Raising [H(2)SO(4)] to 1 M substantiates the suppressing effect of PEG on Cu deposition. This STM study provided atomic- or molecular-level insight into the effect of PEG additives on the deposition of Cu.

Investigation of anti-corrosive properties of poly(aniline-co-2-pyridylamine-co-2,3-xylidine) and its nanocomposite poly(aniline-co-2-pyridylamine-co-2,3-xylidine)/ZnO on mild steel in 0.1 M HCl

NASA Astrophysics Data System (ADS)

Alam, Ruman; Mobin, Mohammad; Aslam, Jeenat

2016-04-01

A soluble terpolymer of aniline (AN), 2-pyridylamine (PA) and 2,3-xylidine (XY), poly(AN-co-PA-co-XY) and its nanocomposite with ZnO nanoparticles namely, poly(AN-co-PA-co-XY)/ZnO were synthesized by chemical oxidative polymerization employing ammonium persulfate as an oxidant. Nanocomposites of homopolymers, polyaniline/ZnO, poly(XY)/ZnO and poly(PA)/ZnO were also synthesized by following similar synthesis route. FTIR, XRD and SEM techniques were used to characterize the synthesized compounds. The synthesized compounds were chemically deposited on mild steel specimens by solvent evaporation method using N-methyl-2-pyrrolidone (NMP) as solvent and 10% epoxy resin (by weight) as binder. Anticorrosive properties of homopolymer nanocomposites, terpolymer and its nanocomposite coatings were studied in 0.1 M HCl by subjecting them to various corrosion tests which includes: free corrosion potential measurement (OCP), weight loss measurements, potentiodynamic polarization, and AC impedance technique. The surface morphology of the corroded and uncorroded coated steel specimens was evaluated using SEM. The corrosion protection performance of terpolymer nanocomposite coating was compared to the terpolymer and individual homopolymers nanocomposites coatings after 30 days immersion in corrosive medium.

Exploring ultrastability in nanostructured glassy polymer films by fast-scanning calorimetry.

NASA Astrophysics Data System (ADS)

Chowdhury, Mithun; Wang, Yucheng; Jeong, Hyuncheol; Cangialosi, Daniele; Priestley, Rodney

A decade ago ultra-stable small molecule glass formers were discovered. Since then a significant amount of research has been devoted to traverse down the energy landscape of such glass formers via physical vapor deposition (PVD). Matrix assisted pulsed laser evaporation (MAPLE) has the known ability to produce vapour deposited nanostructured polymer glass with exceptional kinetic stability. We explored the role of deposition temperature/ growth rate on thermodynamic and kinetic stabilities of poly (methyl methacrylate) (PMMA) films, deposited over a fast-scanning calorimetry sensor. We found in general any MAPLE deposited glass is kinetically more stable than bulk polymer and its spin-coated film. Moreover slow growth rate and optimum temperature during MAPLE deposition can additionally lead to thermodynamically stable (low-energy) glass. The role of interfaces formed through dramatic nanostructuring and packing of nanoglobules (removal of void space) may have additional role on such ultrastability. NSF-MRSEC through PCCM (Grant: DMR-1420541).

Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

PubMed

Papper, Vladislav; Elouarzaki, Kamal; Gorgy, Karine; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

2014-10-13

The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Solvent influence upon structure & throughput of poly vinyledene fluoride thin film nano-patterns by imprint lithography

NASA Astrophysics Data System (ADS)

Sankar, M. S. Ravi; Gangineni, R. B.

2018-04-01

This work aims at understanding the solvent influence upon the throughput and structure of poly vinyledene fluoride (PVDF)nano-patterned films. The PVDF thin films are deposited by spin coating method using Dimethylsulfoxide (DMSO), Tetrahydrofuran (THF) and 2-butanone solvents. The nano-patterns are realized by imprinting SONY 700 MB CD aluminum constructions on PVDF thin filmsusing imprint lithography technique under ambient annealing temperature and pressure. Surface morphology &imprint pattern transfer quality is evaluated with Atomic force microscopy (AFM). Raman spectroscopy is used for evaluating the structural evolutions with respect to solvent & patterning.

Multi-layered poly-dimethylsiloxane as a non-hermetic packaging material for medical MEMS.

PubMed

Lachhman, S; Zorman, C A; Ko, W H

2012-01-01

Poly-dimethylsiloxane (PDMS) is an attractive material for packaging implantable biomedical microdevices owing to its biocompatibility, ease in application, and bio-friendly mechanical properties. Unfortunately, devices encapsulated solely by PDMS lack the longevity for use in chronic implant applications due to defect-related moisture penetration through the packaging layer caused by conventional deposition processes such as spin coating. This paper describes an effort to improve the performance of PDMS as a packaging material by constructing the encapsulant from multiple, thin roller casted layers of PDMS as a part of a polymeric multi-material package.

The interaction of polyglutamine peptides with lipid membranes is regulated by flanking sequences associated with huntingtin.

PubMed

Burke, Kathleen A; Kauffman, Karlina J; Umbaugh, C Samuel; Frey, Shelli L; Legleiter, Justin

2013-05-24

Huntington disease (HD) is caused by an expanded polyglutamine (poly(Q)) repeat near the N terminus of the huntingtin (htt) protein. Expanded poly(Q) facilitates formation of htt aggregates, eventually leading to deposition of cytoplasmic and intranuclear inclusion bodies containing htt. Flanking sequences directly adjacent to the poly(Q) domain, such as the first 17 amino acids on the N terminus (Nt17) and the polyproline (poly(P)) domain on the C-terminal side of the poly(Q) domain, heavily influence aggregation. Additionally, htt interacts with a variety of membraneous structures within the cell, and Nt17 is implicated in lipid binding. To investigate the interaction between htt exon1 and lipid membranes, a combination of in situ atomic force microscopy, Langmuir trough techniques, and vesicle permeability assays were used to directly monitor the interaction of a variety of synthetic poly(Q) peptides with different combinations of flanking sequences (KK-Q35-KK, KK-Q35-P10-KK, Nt17-Q35-KK, and Nt17-Q35-P10-KK) on model membranes and surfaces. Each peptide aggregated on mica, predominately forming extended, fibrillar aggregates. In contrast, poly(Q) peptides that lacked the Nt17 domain did not appreciably aggregate on or insert into lipid membranes. Nt17 facilitated the interaction of peptides with lipid surfaces, whereas the poly(P) region enhanced this interaction. The aggregation of Nt17-Q35-P10-KK on the lipid bilayer closely resembled that of a htt exon1 construct containing 35 repeat glutamines. Collectively, this data suggests that the Nt17 domain plays a critical role in htt binding and aggregation on lipid membranes, and this lipid/htt interaction can be further modulated by the presence of the poly(P) domain.

In situ oligonucleotide synthesis on poly(dimethylsiloxane): a flexible substrate for microarray fabrication

PubMed Central

Moorcroft, Matthew J.; Meuleman, Wouter R. A.; Latham, Steven G.; Nicholls, Thomas J.; Egeland, Ryan D.; Southern, Edwin M.

2005-01-01

In this paper, we demonstrate in situ synthesis of oligonucleotide probes on poly(dimethylsiloxane) (PDMS) microchannels through use of conventional phosphoramidite chemistry. PDMS polymer was moulded into a series of microchannels using standard soft lithography (micro-moulding), with dimensions <100 μm. The surface of the PDMS was derivatized by exposure to ultraviolet/ozone followed by vapour phase deposition of glycidoxypropyltrimethoxysilane and reaction with poly(ethylene glycol) spacer, resulting in a reactive surface for oligonucleotide coupling. High, reproducible yields were achieved for both 6mer and 21mer probes as assessed by hybridization to fluorescent oligonucleotides. Oligonucleotide surface density was comparable with that obtained on glass substrates. These results suggest PDMS as a stable and flexible alternative to glass as a suitable substrate in the fabrication and synthesis of DNA microarrays. PMID:15870385

Electromagnetic interference shielding effectiveness of microcellular polyimide/in situ thermally reduced graphene oxide/carbon nanotubes nanocomposites

NASA Astrophysics Data System (ADS)

Yang, Hongli; Yu, Zhi; Wu, Peng; Zou, Huawei; Liu, Pengbo

2018-03-01

A simple and effective method was adopted to fabricate microcellular polyimide (PI)/reduced graphene oxide (GO)/multi-walled carbon nanotubes (MWCNTs) nanocomposites. Firstly, microcellular poly (amic acid) (PAA)/GO/MWCNTs nanocomposites were prepared through solvent evaporation induced phase separation. In this process, PAA and dibutyl phthalate (DBP) co-dissolved in N,N-dimethylacetamide (DMAc) underwent phase separation with DMAc evaporating, and DBP microdomains were formed in continuous PAA phase. Subsequently, PAA was thermally imidized and simultaneously GO was in situ reduced. After DBP was removed, the microcellular PI/reduced GO (RGO)/MWCNTs nanocomposites were finally obtained. When the initial filler loading was 8 wt%, the electrical conductivity of microcellular PI/RGO, PI/MWCNTs and PI/RGO/MWCNTs nanocomposites were 0.05, 0.02 and 1.87 S·m-1, respectively, and the electromagnetic interference (EMI) shielding efficiency (SE) of microcellular PI/RGO, PI/MWCNTs and PI/RGO/MWCNTs nanocomposites were 13.7-15.1, 13.0-14.3 and 16.6-18.2 dB, respectively. The synergistic effect between RGO and MWCNTs enhanced both the electrical conductivity and EMI shielding performance of the microcellular PI/RGO/MWCNTs nanocomposites. The dominating EMI shielding mechanism for these materials was microwave absorption. While the initial loading of GO and MWCNT was 8 wt%, the microcellular PI/RGO/MWCNTs nanocomposite (500 μm thickness) had extremely high specific EMI SE value of 755-823 dB·cm2·g-1. Its thermal stability was also obviously improved, the 5% weight loss temperature in nitrogen was 548 °C. In addition, it also possessed a high Young's modulus of 789 MPa.

Bioavailability and biodistribution of nanodelivered lutein

USDA-ARS?s Scientific Manuscript database

The aim of the study was to evaluate the ability of poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NP) to enhance lutein bioavailability. The bioavailability of free lutein and PLGA-NP lutein in rats was assessed by determining plasma pharmacokinetics and deposition in selected tissues. Lutein ...

Vertical phase separation of 6,13-bis(triisopropylsilylethynyl) pentacene/poly(methyl methacrylate) blends prepared by electrostatic spray deposition for organic field-effect transistors

NASA Astrophysics Data System (ADS)

Onojima, Norio; Hara, Kazuhiro; Nakamura, Ayato

2017-05-01

Blend films composed of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene) and poly(methyl methacrylate) (PMMA) were prepared by electrostatic spray deposition (ESD). ESD is considered as an intermediate process between dry and wet processes since the solvent present in small droplets can almost be evaporated before arriving at the substrate. Post-drying treatments with the time-consuming evaporation of residual solvents can be omitted. However, it is still not clear that a vertically phase-separated structure can be formed in the ESD process since the vertical phase separation of the blend films is associated with the solvent evaporation. In this study, we fabricated bottom-gate, top-contact organic field-effect transistors based on the blend films prepared by ESD and the devices exhibited transistor behavior with small hysteresis. This result demonstrates that the vertical phase separation of a blend film (upper TIPS pentacene active layer/bottom PMMA gate insulator) can occur in the facile one-step ESD process.

Mixed composition materials suitable for vacuum web sputter coating

NASA Technical Reports Server (NTRS)

Banks, Bruce A.; Rutledge, Sharon K.; Dever, Joyce A.; Bruckner, Eric J.; Walters, Patricia; Hambourger, Paul D.

1996-01-01

Ion beam sputter deposition techniques were used to investigate simultaneous sputter etching of two component targets so as to produce mixed composition films. Although sputter deposition has been largely confined to metals and metal oxides, at least one polymeric material, poly-tetra-fluorethylene, has been demonstrated to produce sputtered fragments which repolymerize upon deposition to produce a highly cross-linked fluoropolymer resembling that of the parent target Fluoropolymer-filled silicon dioxide and fluoropolymer-filled aluminum oxide coatings have been deposited by means of ion beam sputter coat deposition resulting in films having material properties suitable for aerospace and commercial applications. The addition of fluoropolymer to silicon dioxide films was found to increase the hydrophobicity of the resulting mixed films; however, adding fluoropolymer to aluminum oxide films resulted in a reduction in hydrophobicity, thought to be caused by aluminum fluoride formation.

Development of Functional Thin Polymer Films Using a Layer-by-Layer Deposition Technique.

PubMed

Yoshida, Kentaro

2017-01-01

Functional thin films containing insulin were prepared using layer-by-layer (LbL) deposition of insulin and negatively- or positively-charged polymers on the surface of solid substrates. LbL films composed of insulin and negatively-charged polymers such as poly(acrylic acid) (PAA), poly(vinylsulfate) (PVS), and dextran sulfate (DS) were prepared through electrostatic affinity between the materials. The insulin/PAA, insulin/PVS, and insulin/DS films were stable in acidic solutions, whereas they decomposed under physiological conditions as a result of a change in the net electric charge of insulin from positive to negative. Interestingly, the insulin-containing LbL films were stable even in the presence of a digestive-enzyme (pepcin) at pH 1.4 (stomach pH). In contrast, LbL films consisting of insulin and positively-charged polymers such as poly(allylamine hydrochloride) (PAH) decomposed in acidic solutions due to the positive charges of insulin generated in acidic media. The insulin-containing LbL films can be prepared not only on the surface of flat substrates, such as quartz slides, but also on the surface of microparticles, such as poly(lactic acid) (PLA) microbeads. Thus, insulin-containing LbL film-coated PLA microbeads can be handled as a powder. In addition, insulin-containing microcapsules were prepared by coating LbL films on the surface of insulin-doped calcium carbonate (CaCO 3 ) microparticles, followed by dissolution of the CaCO 3 core. The release of insulin from the microcapsules was accelerated at pH 7.4, whereas it was suppressed in acidic solutions. These results suggest the potential use of insulin-containing microcapsules in the development of oral formulations of insulin.

Liquid-phase explosive crystallization of electron-beam-evaporated a-Si films induced by flash lamp annealing

NASA Astrophysics Data System (ADS)

Ohdaira, Keisuke; Matsumura, Hideki

2013-01-01

We succeed in the formation of micrometer-order-thick polycrystalline silicon (poly-Si) films through the flash-lamp-induced liquid-phase explosive crystallization (EC) of precursor a-Si films prepared by electron-beam (EB) evaporation. The velocity of the explosive crystallization (vEC) is estimated to be ˜14 m/s, which is close to the velocity of the liquid-phase epitaxy (LPE) of Si at a temperature around the melting point of a-Si of 1418 K. Poly-Si films formed have micrometer-order-long grains stretched along a lateral crystallization direction, and X-ray diffraction (XRD) and electron diffraction pattern measurements reveal that grains in poly-Si films tend to have a particular orientation. These features are significantly different from our previous results: the formation of poly-Si films containing randomly-oriented 10-nm-sized fine grains formed from a-Si films prepared by catalytic chemical vapor deposition (Cat-CVD) or sputtering. One possible reason for the emergence of a different EC mode in EB-evaporated a-Si films is the suppression of solid-phase nucleation (SPN) during Flash Lamp Annealing (FLA) due to tensile stress which precursor a-Si films originally hold. Poly-Si films formed from EB-evaporated a-Si films would contribute to the realization of high-efficiency thin-film poly-Si solar cells because of large and oriented grains.

New Surface-Enhanced Raman Sensing Chip Designed for On-Site Detection of Active Ricin in Complex Matrices Based on Specific Depurination.

PubMed

Tang, Ji-Jun; Sun, Jie-Fang; Lui, Rui; Zhang, Zong-Mian; Liu, Jing-Fu; Xie, Jian-Wei

2016-01-27

Quick and accurate on-site detection of active ricin has very important realistic significance in view of national security and defense. In this paper, optimized single-stranded oligodeoxynucleotides named poly(21dA), which function as a depurination substrate of active ricin, were screened and chemically attached on gold nanoparticles (AuNPs, ∼100 nm) via the Au-S bond [poly(21dA)-AuNPs]. Subsequently, poly(21dA)-AuNPs were assembled on a dihydrogen lipoic-acid-modified Si wafer (SH-Si), thus forming the specific surface-enhanced Raman spectroscopy (SERS) chip [poly(21dA)-AuNPs@SH-Si] for depurination of active ricin. Under optimized conditions, active ricin could specifically hydrolyze multiple adenines from poly(21dA) on the chip. This depurination-induced composition change could be conveniently monitored by measuring the distinct attenuation of the SERS signature corresponding to adenine. To improve sensitivity of this method, a silver nanoshell was deposited on post-reacted poly(21dA)-AuNPs, which lowered the limit of detection to 8.9 ng mL(-1). The utility of this well-controlled SERS chip was successfully demonstrated in food and biological matrices spiked with different concentrations of active ricin, thus showing to be very promising assay for reliable and rapid on-site detection of active ricin.

Polysialic acid blocks mononuclear phagocyte reactivity, inhibits complement activation, and protects from vascular damage in the retina.

PubMed

Karlstetter, Marcus; Kopatz, Jens; Aslanidis, Alexander; Shahraz, Anahita; Caramoy, Albert; Linnartz-Gerlach, Bettina; Lin, Yuchen; Lückoff, Anika; Fauser, Sascha; Düker, Katharina; Claude, Janine; Wang, Yiner; Ackermann, Johannes; Schmidt, Tobias; Hornung, Veit; Skerka, Christine; Langmann, Thomas; Neumann, Harald

2017-02-01

Age-related macular degeneration (AMD) is a major cause of blindness in the elderly population. Its pathophysiology is linked to reactive oxygen species (ROS) and activation of the complement system. Sialic acid polymers prevent ROS production of human mononuclear phagocytes via the inhibitory sialic acid-binding immunoglobulin-like lectin-11 (SIGLEC11) receptor. Here, we show that low-dose intravitreal injection of low molecular weight polysialic acid with average degree of polymerization 20 (polySia avDP20) in humanized transgenic mice expressing SIGLEC11 on mononuclear phagocytes reduced their reactivity and vascular leakage induced by laser coagulation. Furthermore, polySia avDP20 prevented deposition of the membrane attack complex in both SIGLEC11 transgenic and wild-type animals. In vitro, polySia avDP20 showed two independent, but synergistic effects on the innate immune system. First, polySia avDP20 prevented tumor necrosis factor-α, vascular endothelial growth factor A, and superoxide production by SIGLEC11-positive phagocytes. Second, polySia avDP20 directly interfered with complement activation. Our data provide evidence that polySia avDP20 ameliorates laser-induced damage in the retina and thus is a promising candidate to prevent AMD-related inflammation and angiogenesis. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

Influence of Poly(L-Lactic Acid) Nanofibers and BMP-2–Containing Poly(L-Lactic Acid) Nanofibers on Growth and Osteogenic Differentiation of Human Mesenchymal Stem Cells

PubMed Central

Schofer, Markus D.; Fuchs-Winkelmann, Susanne; Gräbedünkel, Christian; Wack, Christina; Dersch, Roland; Rudisile, Markus; Wendorff, Joachim H.; Greiner, Andreas; Paletta, Jürgen R. J.; Boudriot, Ulrich

2008-01-01

The aim of this study was to characterize synthetic poly-(L-lactic acid) (PLLA) nanofibers concerning their ability to promote growth and osteogenic differentiation of stem cells in vitro, as well as to test their suitability as a carrier system for growth factors. Fiber matrices composed of PLLA or BMP-2–incorporated PLLA were seeded with human mesenchymal stem cells and cultivated over a period of 22 days under growth and osteoinductive conditions, and analyzed during the course of culture, with respect to gene expression of alkaline phosphatase (ALP), osteocalcin (OC), and collagen I (COL-I). Furthermore, COL-I and OC deposition, as well as cell densities and proliferation, were analyzed using fluorescence microscopy. Although the presence of nanofibers diminished the dexamethasone-induced proliferation, there were no differences in cell densities or deposition of either COL-I or OC after 22 days of culture. The gene expression of ALP, OC, and COL-I decreased in the initial phase of cell cultivation on PLLA nanofibers as compared to cover slip control, but normalized during the course of cultivation. The initial down-regulation was not observed when BMP-2 was directly incorporated into PLLA nanofibers by electrospinning, indicating that growth factors like BMP-2 might survive the spinning process in a bioactive form. PMID:19112539

Growth of cubic silicon carbide on oxide using polysilicon as a seed layer for micro-electro-mechanical machine applications

NASA Astrophysics Data System (ADS)

Frewin, C. L.; Locke, C.; Wang, J.; Spagnol, P.; Saddow, S. E.

2009-08-01

The growth of highly oriented 3C-SiC directly on an oxide release layer, composed of a 20-nm-thick poly-Si seed layer and a 550-nm-thick thermally deposited oxide on a (1 1 1)Si substrate, was investigated as an alternative to using silicon-on-insulator (SOI) substrates for freestanding SiC films for MEMS applications. The resulting SiC film was characterized by X-ray diffraction (XRD) with the X-ray rocking curve of the (1 1 1) diffraction peak displaying a FWHM of 0.115° (414″), which was better than that for 3C-SiC films grown directly on (1 1 1)Si during the same deposition process. However, the XRD peak amplitude for the 3C-SiC film on the poly-Si seed layer was much less than for the (1 1 1)Si control substrate, due to slight in-plane misorientations in the film. Surprisingly, the film was solely composed of (1 1 1) 3C-SiC grains and possessed no 3C-SiC grains oriented along the <3 1 1> and <1 1 0> directions which were the original directions of the poly-Si seed layer. With this new process, MEMS structures such as cantilevers and membranes can be easily released leaving behind high-quality 3C-SiC structures.

Aligning Ag Nanowires by a Facile Bioinspired Directional Liquid Transfer: Toward Anisotropic Flexible Conductive Electrodes.

PubMed

Meng, Lili; Bian, Ruixin; Guo, Cheng; Xu, Bojie; Liu, Huan; Jiang, Lei

2018-06-01

Recent years have witnessed the booming development of transparent flexible electrodes (TFEs) for their applications in electronics and optoelectronic devices. Various strategies have thus been developed for preparing TFEs with higher flexibility and conductivity. However, little work has focused on TFEs with anisotropic conductivity. Here, a facile strategy of directional liquid transfer is proposed, guided by a conical fibers array (CFA), based on which silver nanowires (AgNWs) are aligned on a soft poly(ethylene terephthalate) substrate in large scale. After further coating a second thin layer of the conductive polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), a TFE with notable anisotropic conductivity and excellent optical transmittance of 95.2% is prepared. It is proposed that the CFA enables fine control over the receding of the three-phase contact line during the dewetting process, where AgNWs are guided and aligned by the as-generated directional stress. Moreover, anisotropic electrochemical deposition is enabled where the Cu nanoparticles deposit only on the oriented AgNWs, leading to a surface with anisotropic wetting behavior. Importantly, the approach enables alignment of AgNWs via multiple directions at one step. It is envisioned that the as-developed approach will provide an optional approach for simple and low-cost preparation of TFE with various functions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel Polymeric Dielectric Materials for the Additive Manufacturing of Microwave Devices

NASA Astrophysics Data System (ADS)

O'Keefe, Shamus E.

The past decade has seen a rapid increase in the deployment of additive manufacturing (AM) due to the perceived benefits of lower cost, higher quality, and a smaller environmental footprint. And while the hardware behind most of AM processes is mature, the study and development of material feedstock(s) are in their infancy, particularly so for niche areas. In this dissertation, we look at novel polymeric materials to support AM for microwave devices. Chapter 1 provides an overview of the benefits of AM, followed by the specific motivation for this work, and finally a scope defining the core objectives. Chapter 2 delves into a higher-level background of dielectric theory and includes a brief overview of the two common dielectric spectroscopy techniques used in this work. The remaining chapters, summarized below, describe experiments in which novel polymeric materials were developed and their microwave dielectric properties measured. Chapter 3 describes the successful synthesis of polytetrafluroethylene (PTFE)/polyacrylate (PA) core-shell nanoparticles and their measured microwave dielectric properties. PTFE/PA core-shell nanoparticles with spherical morphology were successfully made by aerosol deposition followed by a brief annealing. The annealing temperature is closely controlled to exceed the glass transition (Tg) of the PA shell yet not exceed the Tg of the PTFE core. Furthermore, the annealing promotes coalescence amongst the PA shells of neighboring nanoparticles and results in the formation of a contiguous PA matrix that has excellent dispersion of PTFE cores. The measured dielectric properties agree well with theoretical predictions and suggest the potential of this material as a feedstock for AM microwave devices. Chapter 4 delves into the exploration of various polyimide systems with the aim of replacing the PA in the previously studied PTFE/PA core-shell nanoparticles. Fundamental relationships between polymer attributes (flexibility/rigidity and functional groups) and dielectric properties were explored. The results indicate that backbone rigidity and the inclusion of fluorine lead to excellent dielectric properties, however, often at the expense of mechanical properties. Chapter 5 explores the optimization of PTFE core-shell nanoparticles via a novel PTFE/polyimide (PI) core-shell nanoparticle. PTFE/PI core-shell nanoparticles were synthesized via electrostatic interaction between the PTFE cores and a PI precursor, poly(amic) acid salt (PAAS). The PAAS is converted to PI by thermal imidization. The PI has properties superior to those of PA for microwave applications and the results suggest the promise of PTFE/PI core-shell nanoparticles for use in AM of microwave devices. Chapter 6 describes the first report of on actively-tunable microwave substrate made possible by a semiconducting polymer composite blend. The composite blend is comprised of poly(3-hexylthiophene) (P3HT) as the semiconducting polymer and [6,6]-Phenyl C61 butyric acid methyl ester (PCBM) while the remainder of the composite is comprised of a low dielectric constant polymer polydimethylsiloxane (PDMS). When subjected to photo excitation (white light, spectrum centered at 532 nm), the composite exhibits a tunability of the permittivity up to 20%. The results suggest strong promise for the use of semiconducting polymers in actively-tunable microwave devices. Finally, Chapter 7 presents a summary of the salient conclusions of the reported studies. The chapter concludes with a few brief remarks of my personal experience as a non-traditional student and the challenges therein.

Surface analytical characterization of Streptavidin/poly(3-hexylthiophene) bilayers for bio-electronic applications

NASA Astrophysics Data System (ADS)

Sportelli, M. C.; Picca, R. A.; Manoli, K.; Re, M.; Pesce, E.; Tapfer, L.; Di Franco, C.; Cioffi, N.; Torsi, L.

2017-10-01

The analytical performance of bioelectronic devices is highly influenced by their fabrication methods. In particular, the final architecture of field-effect transistor biosensors combining spin-cast poly(3-hexylthiophene) (P3HT) film and a biomolecule interlayer deposited on a SiO2/Si substrate can lead to the development of highly performing sensing systems, such as for the case of streptavidin (SA) used for biotin sensing. To gain a better understanding of the quality of the interfacial area, critical is the assessment of the morphological features characteristic of the adopted biolayer deposition protocol, namely: the layer-by-layer (LbL) approach and the spin coating technique. The present study relies on a combined surface spectroscopic and morphological characterization. Specifically, X-ray photoelectron spectroscopy operated in the parallel angle-resolved mode allowed the non-destructive investigation of the in-depth chemical composition of the SA film, alone or in the presence of the P3HT overlayer. Spectroscopic data were supported and corroborated by the results obtained with a Scanning Electron and a Helium Ion microscope investigation performed on the SA layer that provided relevant information on the protein structural arrangement or on its surface morphology. Clear differences emerged between the SA layers prepared by the two approaches, with the layer-by-layer deposition resulting in a smoother and better defined bio-electronic interface. Such findings support the superior analytical performance shown by bioelectronic devices based on LbL-deposited protein layers over spin coated ones.

Ionic Driven Embedment of Hyaluronic Acid Coated Liposomes in Polyelectrolyte Multilayer Films for Local Therapeutic Delivery

NASA Astrophysics Data System (ADS)

Hayward, Stephen L.; Francis, David M.; Sis, Matthew J.; Kidambi, Srivatsan

2015-10-01

The ability to control the spatial distribution and temporal release of a therapeutic remains a central challenge for biomedical research. Here, we report the development and optimization of a novel substrate mediated therapeutic delivery system comprising of hyaluronic acid covalently functionalized liposomes (HALNPs) embedded into polyelectrolyte multilayer (PEM) platform via ionic stabilization. The PEM platform was constructed from sequential deposition of Poly-L-Lysine (PLL) and Poly(Sodium styrene sulfonate) (SPS) “(PLL/SPS)4.5” followed by adsorption of anionic HALNPs. An adsorption affinity assay and saturation curve illustrated the preferential HALNP deposition density for precise therapeutic loading. (PLL/SPS)2.5 capping layer on top of the deposited HALNP monolayer further facilitated complete nanoparticle immobilization, cell adhesion, and provided nanoparticle confinement for controlled linear release profiles of the nanocarrier and encapsulated cargo. To our knowledge, this is the first study to demonstrate the successful embedment of a translatable lipid based nanocarrier into a substrate that allows for temporal and spatial release of both hydrophobic and hydrophilic drugs. Specifically, we have utilized our platform to deliver chemotherapeutic drug Doxorubicin from PEM confined HALNPs. Overall, we believe the development of our HALNP embedded PEM system is significant and will catalyze the usage of substrate mediated delivery platforms in biomedical applications.

Liquid eutectic GaIn as an alternative electrode for PTB7:PCBM organic solar cells

NASA Astrophysics Data System (ADS)

Thanh Hau Pham, Viet; Kieu Trinh, Thanh; Tam Nguyen Truong, Nguyen; Park, Chinho

2017-04-01

Conventional vacuum deposition process of aluminum (Al) is costly, time-consuming and difficult to apply to the large-scale production of organic photovoltaic devices (OPV). This paper reports a vacuum-free fabrication process of poly[[4,8-bis(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b‧]dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thienophenediyl]:[6,6]-phenyl C71 butyric acid methyl ester (PTB7:PCBM) bulk heterojunction organic solar cell with liquid eutectic gallium-indium (EGaIn) electrode as an alternative to the common Al electrode. The insertion of a thin poly(ethylene oxide) (PEO) layer after depositing organic photoactive layer could help prevent the diffusion of liquid EGaIn into the active layer and allow the deposition of the EGaIn electrode. The PEO interfacial layer was formed by spin-coating from a mixed solvent of alcohol and water. Among different alcohol+water (methanol, ethanol, ethylene glycol, n-propanol, isopropanol, and isobutanol) mixed solvent tested, the n-propanol+water mixed solvent showed the greatest enhancement to the performance of OPVs. The improved device performance was attributed to the reactivity of mixed solvent n-propanol+water toward the surface of PTB7:PCBM active layer, which could help optimize surface morphology.

Initiated chemical vapor deposition polymers for high peak-power laser targets

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

Baxamusa, Salmaan H.; Lepro, Xavier; Lee, Tom

2016-12-05

Here, we report two examples of initiated chemical vapor deposition (iCVD) polymers being developed for use in laser targets for high peak-power laser systems. First, we show that iCVD poly(divinylbenzene) is more photo-oxidatively stable than the plasma polymers currently used in laser targets. Thick layers (10–12 μm) of this highly crosslinked polymer can be deposited with near-zero intrinsic film stress. Second, we show that iCVD epoxy polymers can be crosslinked after deposition to form thin adhesive layers for assembling precision laser targets. The bondlines can be made as thin as ~ 1 μm, approximately a factor of 2 thinner thanmore » achievable using viscous resin-based adhesives. These bonds can withstand downstream coining and stamping processes.« less

A Study of the Delivery of Adult Walk-In Primary Care at Womack Army Hospital, Fort Bragg, North Carolina

DTIC Science & Technology

1980-05-01

patients have begun arriving, they start out behind and they continue to get further behind as the morning progresses. This factor was brought to the...program and give a false indication of the actual time that paients had to spend in the AMOSIST program to get definitive care. It can be seen in...AMOSISTs in the AMIC. In the mornings, when the arrival rate and the patient load are the heaviest, there was a tendency for the physician to get somewhat

Synthesis and Purification of Tunable High Tg Electro-Optical Polymers by Ring Opening Metathesis Polymerization

DTIC Science & Technology

2011-09-01

The amic acid was dissolved in DMF (100 mL) at 100 °C. Acetic anhydride (14.8 g, 0.145 mol) and anhydrous sodium acetate (0.8 g, 0.01 mol) were...exo-N-[(E)-2-(ethyl(4-((4-nitrophenyl)diazenyl)phenyl)amino)ethyl benzoate ] nadimide (5). DPTS (0.44 g, 1.41 mmol), exo-N-(p-Carboxyphenyl...agent for a Ru-based catalyst when extracted with aqueous sodium bicarbonate (28, 29). We reasoned that MNA could enhance the solubility of the

Elastomer toughened polyimide adhesives. [bonding metal and composite material structures for aircraft and spacecraft

NASA Technical Reports Server (NTRS)

St.clair, A. K.; St.clair, T. L. (Inventor)

1985-01-01

A rubber-toughened, addition-type polyimide composition is disclosed which has excellent high temperature bonding characteristics in the fully cured state and improved peel strength and adhesive fracture resistance physical property characteristics. The process for making the improved adhesive involves preparing the rubber-containing amic acid prepolymer by chemically reacting an amine-terminated elastomer and an aromatic diamine with an aromatic dianhydride with which a reactive chain stopper anhydride has been mixed, and utilizing solvent or mixture of solvents for the reaction.

Wave Propagation and Dynamics of Lattice Structures.

DTIC Science & Technology

1984-05-01

Progress in Solid Mechanics, North Holand Publishing Company, Amsterdam, 1960. [7) Y. K. Linn, and T. J. McDaniel, ’n)amics of Beam Type Periodic...deformation. -99- APPENDIX F FREQUENCY RESPONSE AND IMPULSE RESPONSE FUNCTIONS FOR LONGITUDINAL VIBRATION IN AN ELASTIC ROD Figure F1 shows the elastic rod to b...6 (F38) Rearranging eqn. (F38), .HE(w) = e’ 4e~3 ~e e 2 e1" +e " 6 e r (F39) Mlultiplying eqn. ( F1 =39) by 6Ŕ 6- and aragn te - . e 6 -e _ aix

A Simulation Study on Take-Off and Landing Dynamics of the Aircraft of a Fly-By-Wire Control System

DTIC Science & Technology

1993-01-07

L:V,"DIN G DYN;AMICS OF THE AIRCRAFT OF A FLY-BY-WIRE CONTROL SYSTEM by Y achang Feng, Gang Chert, Peiqiong Li 93-00985 Distribution unlimit ed. FASTC...FLY-BY-WIRE CONTROL SYSTEM By: Yachang Feng, Gang Chen, Peiqiong- Li English pages: 17 Source: Hangkon, Xuebao, Vol. 12, No. 6, June, 1991; pp. 252-258...Landing Dynamics of the Aircraft of a Fly-By-Wire Control System Beijing University of Aeronautics and Astronautics Yachang FENG, Gang CHEN and Peiqiong Li

Interactions of Graphene Oxide Nanomaterials with Natural Organic Matter and Metal Oxide Surfaces

EPA Science Inventory

Interactions of graphene oxide (GO) with silica surfaces were investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D). Both GO deposition and release were monitored on silica- and poly-l-lysine (PLL) coated surfaces as a function of GO concentration a...

A REGIONAL MODEL FOR PCDD/F'S BASED ON A PHOTOCHEMICAL MODEL FOR AIR QUALITY AND PARTICULATE MATTER

EPA Science Inventory

How important is gas to particle partitioning in predicting air concentrations and deposition of Poly-Chlorinated Dibenzo-p-Dioxins and Furans (PCDD/F's)? Literature indicates that the fate of emissions changes because the summation of atmospheric processes has a different balanc...

One-step microwave plasma enhanced chemical vapor deposition (MW-PECVD) for transparent superhydrophobic surface

NASA Astrophysics Data System (ADS)

Thongrom, Sukrit; Tirawanichakul, Yutthana; Munsit, Nantakan; Deangngam, Chalongrat

2018-02-01

We demonstrate a rapid and environmental friendly fabrication technique to produce optically clear superhydrophobic surfaces using poly (dimethylsiloxane) (PDMS) as a sole coating material. The inert PDMS chain is transformed into a 3-D irregular solid network through microwave plasma enhanced chemical vapor deposition (MW-PECVD) process. Thanks to high electron density in the microwave-activated plasma, coating can be done in just a single step with rapid deposition rate, typically much shorter than 10 s. Deposited layers show excellent superhydrophobic properties with water contact angles of ∼170° and roll-off angles as small as ∼3°. The plasma-deposited films can be ultrathin with thicknesses under 400 nm, greatly diminishing the optical loss. Moreover, with appropriate coating conditions, the coating layer can even enhance the transmission over the entire visible spectrum due to a partial anti-reflection effect.

Propagation losses in undoped and n-doped polycrystalline silicon wire waveguides.

PubMed

Zhu, Shiyang; Fang, Q; Yu, M B; Lo, G Q; Kwong, D L

2009-11-09

Polycrystalline silicon (polySi) wire waveguides with width ranging from 200 to 500 nm are fabricated by solid-phase crystallization (SPC) of deposited amorphous silicon (a-Si) on SiO(2) at a maximum temperature of 1000 degrees C. The propagation loss at 1550 nm decreases from 13.0 to 9.8 dB/cm with the waveguide width shrinking from 500 to 300 nm while the 200-nm-wide waveguides exhibit quite large loss (>70 dB/cm) mainly due to the relatively rough sidewall of waveguides induced by the polySi dry etch. By modifying the process sequence, i.e., first patterning the a-Si layer into waveguides by dry etch and then SPC, the sidewall roughness is significantly improved but the polySi crystallinity is degraded, leading to 13.9 dB/cm loss in the 200-nm-wide waveguides while larger losses in the wider waveguides. Phosphorus implantation causes an additional loss in the polySi waveguides. The doping-induced optical loss increases relatively slowly with the phosphorus concentration increasing up to 1 x 10(18) cm(-3), whereas the 5 x 10(18) cm(-3) doped waveguides exhibit large loss due to the dominant free carrier absorption. For all undoped polySi waveguides, further 1-2 dB/cm loss reduction is obtained by a standard forming gas (10%H(2) + 90%N(2)) annealing owing to the hydrogen passivation of Si dangling bonds present in polySi waveguides, achieving the lowest loss of 7.9 dB/cm in the 300-nm-wide polySi waveguides. However, for the phosphorus doped polySi waveguides, the propagation loss is slightly increased by the forming gas annealing.

Electron injection from graphene quantum dots to poly(amido amine) dendrimers

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

Lin, T. N.; Inciong, M. R.; Santiago, S. R.

2016-04-18

The steady-state and time-resolved photoluminescence (PL) are used to study the electron injection from graphene quantum dots (GQDs) to poly(amido amine) (PAMAM) dendrimers. The PL is enhanced by depositing GQDs on the surfaces of the PAMAM dendrimers. The maximum enhancement of PL with a factor of 10.9 is achieved at a GQD concentration of 0.9 mg/ml. The dynamics of PL in the GQD/PAMAM composite are analyzed, evidencing the existence of electron injection. On the basis of Kelvin probe measurements, the electron injection from the GQDs to the PAMAM dendrimers is accounted for by the work function difference between them.

Measurements and sensitivities of LWR in poly spacers

NASA Astrophysics Data System (ADS)

Ayal, Guy; Shauly, Eitan; Levi, Shimon; Siany, Amit; Adan, Ofer; Shacham-Diamand, Yosi

2010-03-01

LER and LWR have long been considered a primary issue in process development and monitoring. Development of a low power process flavors emphasizes the effect of LER, LWR on different aspects of the device. Gate level performance, particularly leakage current at the front end of line, resistance and reliability in the back-end layers. Traditionally as can be seen in many publications, for the front end of line the focus is mainly on Poly and Active area layers. Poly spacers contribution to the gate leakage, for example, is rarely discussed. Following our research done on sources of gate leakage, we found leakage current (Ioff) in some processes to be highly sensitive to changes in the width of the Poly spacers - even more strongly to the actual Poly gate CDs. Therefore we decided to measure Poly spacers LWR, its correlation to the LWR in the poly, and its sensitivity to changes in layout and OPC. In our last year publication, we defined the terms LLER (Local Line Edge Roughness) and LLWR (Local Line Width Roughness). The local roughness is measured as the 3-sigma value of the line edge/width in a 5-nm segment around the measurement point. We will use these terms in this paper to evaluate the Poly roughness impact on Poly spacer's roughness. A dedicated test chip was designed for the experiments, having various transistors layout configurations with different densities to cover the all range of process design rules. Applied Materials LER and LWR innovative algorithms were used to measure and characterize the spacer roughness relative to the distance from the active edges and from other spaces. To accurately measure all structures in a reasonable time, the recipes were automatically generated from CAD. On silicon, after poly spacers generation, the transistors no longer resemble the Poly layer CAD layout, their morphology is different compared with Photo/Etch traditional structures , and dimensions vary significantly. In this paper we present metrology and characterization of poly spacer LLWR and LLER compared to that of the poly gate in various transistor shapes, showing that the relation between them depends on the transistor architecture (final layout, including OPC). We will show how the spacer deposition may reduce, keep or even enlarge the roughness measured on Poly, depending on transistor layout , but surprisingly, not dependent on proximity effects.

All-solution-processed PbS quantum dot solar modules

NASA Astrophysics Data System (ADS)

Jang, Jihoon; Shim, Hyung Cheoul; Ju, Yeonkyeong; Song, Jung Hoon; An, Hyejin; Yu, Jong-Su; Kwak, Sun-Woo; Lee, Taik-Min; Kim, Inyoung; Jeong, Sohee

2015-05-01

A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm2, exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm2 unit cell). Our approach affords trade-offs between power and the active area of the photovoltaic devices, which results in a low-cost power source, and which is scalable to larger areas.A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm2, exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm2 unit cell). Our approach affords trade-offs between power and the active area of the photovoltaic devices, which results in a low-cost power source, and which is scalable to larger areas. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01508a

Selective, ultrathin membrane skins prepared by deposition of novel polymer films on porous alumina supports

NASA Astrophysics Data System (ADS)

Balachandra, Anagi Manjula

Membrane-based separations are attractive in industrial processes because of their low energy costs and simple operation. However, low permeabilities often make membrane processes uneconomical. Since flux is inversely proportional to membrane thickness, composite membranes consisting of ultrathin, selective skins on highly permeable supports are required to simultaneously achieve high throughput and high selectivity. However, the synthesis of defect-free skins with thicknesses less than 50 nm is difficult, and thus flux is often limited. Layer-by-layer deposition of oppositely charged polyelectrolytes on porous supports is an attractive method to synthesize ultrathin ion-separation membranes with high flux and high selectivity. The ion-transport selectivity of multilayer polyelectrolyte membranes (MPMs) is primarily due to Donnan exclusion; therefore increase in fixed charge density should yield high selectivity. However, control over charge density in MPMs is difficult because charges on polycations are electrostatically compensated by charges on polyanions, and the net charge in the bulk of these films is small. To overcome this problem, we introduced a templating method to create ion-exchange sites in the bulk of the membrane. This strategy involves alternating deposition of a Cu2+-poly(acrylic acid) complex and poly(allylamine hydrochloride) on a porous alumina support followed by removal of Cu2+ and deprotonation to yield free -COO- ion-exchange sites. Diffusion dialysis studies showed that the Cl-/SO42-. Selectivity of Cu2+-templated membranes is 4-fold higher than that of membranes prepared in the absence of Cu2+. Post-deposition cross-linking of these membranes by heat-induced amide bond formation further increased Cl-/SO42- selectivity to values as high as 600. Room-temperature, surface-initiated atom transfer radical polymerization (ATRP) provides another convenient method for formation of ultrathin polymer skins. This process involves attachment of polymerization initiators to a porous alumina support and subsequent polymerization from these initiators. Because ATRP is a controlled polymerization technique, it yields well-defined polymer films with low polydispersity indices (narrow molecular weight distributions). Additionally, this method is attractive because film thickness can be easily controlled by adjusting polymerization time. Gas-permeability data showed that grafted poly(ethylene glycol dimethacrylate) membranes have a CO 2/CH4 selectivity of 20, whereas poly(2-hydroxyethyl methacrylate) (PHEMA) films grown from a surface have negligible selectivity. However, derivatization of PHEMA with pentadecafluorooctanoyl chloride increases the solubility of CO2 in the membrane and results in a CO2/CH4 selectivity of 9. Although composite PHEMA membranes have no significant gas-transport selectivity, diffusion dialysis studies with PHEMA membranes showed moderate ion-transport selectivities. Cross-linking of PHEMA membranes by reaction with succinyl chloride greatly enhanced anion-transport selectivities while maintaining reasonable flux. The selectivities of these systems demonstrate that alternating polyelectrolyte deposition and surface-initiated ATRP are indeed capable of forming ultrathin, defect-free membrane skins that can potentially be modified for specific separations.

All-Arthroscopic Autologous Matrix-Induced Chondrogenesis-Aided Repair of a Patellar Cartilage Defect Using Dry Arthroscopy and a Retraction System.

PubMed

Sadlik, Boguslaw; Puszkarz, Mariusz; Kosmalska, Lidia; Wiewiorski, Martin

2017-11-01

The technique of all-arthroscopic autologous matrix-induced chondrogenesis (AMIC)-aided repair of patellar cartilage lesions using a retraction system and dry arthroscopy has been recently described. We report the first clinical and radiological data at a short-term follow-up. Twelve patients underwent AMIC-aided cartilage repair for a patellar lesion. All steps of the procedure were performed arthroscopically, which include the use of an intra-articularly placed retraction plate for distraction of the patellofemoral joint and evacuation of saline solution for collagen matrix insertion and fixation. Clinical assessment performed before surgery and at a mean follow-up time of 38 months (range: 24-70) included the following scores: Knee Injury and Osteoarthritis Outcome Score (KOOS), International Knee Documentation Committee (IKDC), and visual analog scale (VAS). Magnetic resonance imaging was performed at the follow-up examination, including the magnetic resonance observation of cartilage repair tissue (MOCART) score. The mean KOOS and IKDC scores increased significantly ( p  < 0.01) from 50.3 and 37.4 points preoperatively to 90.1 and 79.4 postoperatively. The VAS score decreased from 7.8 to 2.3 points. Mean MOCART score at follow-up was 58.3 points. Cartilage repair of patellar lesions aided by a retraction system in a dry arthroscopy setup is a promising approach. Further studies are needed to evaluate this procedure and compare it to existing matrix implantation techniques. The level of evidence for the study is 4 (case series). Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

The 3F condensation polyimides: Review and update

NASA Technical Reports Server (NTRS)

Alston, William B.; Gratz, Roy F.

1989-01-01

Nine new condensation polyimides containing the phenyltrifluoroethylidene (3F) linkage were synthesized by the amic-acid route. Several other polyimides, including some with hexafluoroisopropylidene (6F) linkage, were also prepared as controls. Amic-acid solutions were characterized by determining their inherent viscosities prior to thermal conversion into polyimide films. Glass transition temperatures (T sub g), thermogravimetric analysis (TGA), and isothermal weight loss data (at 316, 371, and 371 C under 0.5 MPa air pressure) were obtained for the films. The films were pulverized into molding powders which, in turn, were thermally processed under pressure into neat resin disks. The disks were also characterized by T sub g's and 316 and 371 C isothermal weight losses. The film study identified two new polyimides with T sub g's greater than 371 C and two new polyimides with low rates of weight loss. The resin disks exhibited the same overall trends in T sub g and weight loss as the respective films, however the weight loss per unit surface area was always greater, presumably due to molecular degradation induced during preparation of the molding powders. The overall results indicate that polyimides containing the 3F linkage have T sub g's and thermo-oxidative stability comparable to polyimides containing the 6F group. Alternate technology was also shown by the synthesis of two new polyalkyl substituted 3F diamines and five more new 3F polymers. Their potential as photoresists was demonstrated by T sub g advancement after ultraviolet exposure. Last, four U.S. patents on 3F monomers and polymers were issued and up to eight more are pending.

Analysis of Semiconductor Structures by Nuclear and Electrical Techniques.

DTIC Science & Technology

temperatures well below the Si-Al eutectic (577C), fine grained polycrystalline Si in contact with Al films recrystallizes in the Al matrix. The... recrystallization can be deferred or suppressed by placing a buffer layer of V or Ti between the Al film and poly Si. (2) When annealing Pt films deposited on Si

Clinical benefits of a new multipurpose disinfecting solution in silicone hydrogel and soft contact lens users.

PubMed

Campbell, Robert; Kame, Gregory; Leach, Norman; Paul, Matthew; White, Eric; Zigler, Lamar

2012-03-01

To evaluate the safety and efficacy of a new multipurpose disinfecting solution (MPDS) containing a diblock copolymer, poly(oxyethylene)-poly(oxybutylene), designed to improve the wetting properties of silicone-hydrogel lenses. This 90-day, randomized, concurrently controlled, double-masked, multisite study involved 573 subjects at 30 investigational sites in the United states. Existing lens wearers were randomly assigned to either regimen 1 (OPTI-FREE PureMoist, a newly developed formulation, Alcon Laboratories Inc., Fort Worth, TX) or regimen 2 (renu fresh, Bausch and Lomb Inc., Rochester, NY). At baseline, days 7, 30, 60, and 90, the subjects recorded subjective evaluations relating to lens acceptability and comfort, wearing time, and rewetting drop frequency, whereas investigators assessed slitlamp findings (including corneal fluorescein staining), lens deposits (modified Rudko), visual acuity, and adverse events. Group IV lenses were collected for ex vivo measurement of lysozyme deposits. Differences favoring regimen 1 were noted on day 90 for subjective evaluations of lens comfort (insertion, removal, overall); lens moisture and freshness; gentle on eye; clear vision; and lens handling (all P<0.004). Corneal fluorescein staining severity and area and lysozyme deposits (group IV lenses) were lower with regimen 1 (P<0.0001). This 90-day study shows that the new MPDS designed for silicone-hydrogel lenses is safe and effective when used by both silicone-hydrogel and traditional soft lens wearers. By improving comfort and decreasing lysozyme deposits and corneal fluorescein staining, the new MPDS enhances patients' wearing experience and helps maintain optimal lens performance.

Heuristic method of fabricating counter electrodes in dye-sensitized solar cells based on a PEDOT:PSS layer as a catalytic material

NASA Astrophysics Data System (ADS)

Edalati, Sh; Houshangi far, A.; Torabi, N.; Baneshi, Z.; Behjat, A.

2017-02-01

Poly(3,4-ethylendioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was deposited on a fluoride-doped tin oxide glass substrate using a heuristic method to fabricate platinum-free counter electrodes for dye-sensitized solar cells (DSSCs). In this heuristic method a thin layer of PEDOT:PPS is obtained by spin coating the PEDOT:PSS on a Cu substrate and then removing the substrate with FeCl3. The characteristics of the deposited PEDOT:PSS were studied by energy dispersive x-ray analysis and scanning electron microscopy, which revealed the micro-electronic specifications of the cathode. The aforementioned DSSCs exhibited a solar conversion efficiency of 3.90%, which is far higher than that of DSSCs with pure PEDOT:PSS (1.89%). This enhancement is attributed not only to the micro-electronic specifications but also to the HNO3 treatment through our heuristic method. The results of cyclic voltammetry, electrochemical impedance spectroscopy (EIS) and Tafel polarization plots show the modified cathode has a dual function, including excellent conductivity and electrocatalytic activity for iodine reduction.

Effects of UV Aging on the Cracking of Titanium Oxide Layer on Poly(ethylene terephthalate) Substrate: Preprint

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

Zhang, Chao; Gray, Matthew H.; Tirawat, Robert

Thin oxide and metal films deposited on polymer substrates is an emerging technology for advanced reflectors for concentrated solar power applications, due to their unique combination of light weight, flexibility and inexpensive manufacture. Thus far, there is little knowledge on the mechanical integrity or structural persistence of such multi-layer thin film systems under long-term environmental aging. In this paper, the cracking of a brittle titanium dioxide layer deposited onto elasto-plastic poly(ethylene terephthalate) (PET) substrate is studied through a combination of experiment and modeling. In-situ fragmentation tests have been conducted to monitor the onset and evolution of cracks both on pristinemore » and on samples aged with ultraviolet (UV) light. An analytical model is presented to simulate the cracking behavior and to predict the effects of UV aging. Based on preliminary experimental observation, the effect of aging is divided into three aspects and analyzed independently: mechanical property degradation of the polymer substrate; degradation of the interlayer between substrate and oxide coating; and internal stress-induced cracks on the oxide coating.« less

Reaction products and oxide thickness formed by Ti out-diffusion and oxidization in poly-Pt/Ti/SiO 2/Si with oxide films deposited

NASA Astrophysics Data System (ADS)

Chen, Changhong; Huang, Dexiu; Zhu, Weiguang; Feng, Yi; Wu, Xigang

2006-08-01

In the paper, we present experimental results to enhance the understanding of Ti out-diffusion and oxidization in commercial poly-Pt/Ti/SiO 2/Si wafers with perovskite oxide films deposited when heat-treated in flowing oxygen ambient. It indicates that when heat-treated at 550 and 600 °C, PtTi 3+PtTi and PtTi are the reaction products from interfacial interaction, respectively; while heat-treated at 650 °C and above, the products become three layers of titanium oxides instead of the alloys. Confirmed to be rutile TiO 2, the first two layers spaced by 65 nm encapsulate the Pt surface by the first layer with 60 nm thick forming at its surface and by the next layer with 35 nm thick inserting its original layer. In addition, the next layer is formed as a barrier to block up continuous diffusion paths of Ti, and thus results in the last layer of TiO 2- x formed by the residual Ti oxidizing.

Photocatalytic activity of CdS and Ag2S quantum dots deposited on poly(amidoamine) functionalized carbon nanotubes

PubMed Central

Neelgund, Gururaj M.; Oki, Aderemi

2011-01-01

Two novel ternary nanocatalysts, f-MWCNTs-CdS and f-MWCNTs-Ag2S were successfully constructed by covalent grafting of fourth generation (G4) hyperbranched, crosslinked poly(amidoamine) (PAMAM) to carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and subsequent deposition of CdS or Ag2S quantum dots (QDs). The structural transformation, surface potential, and morphology of functionalized MWCNTs (f-MWCNTs) and nanocatalysts were characterized by UV-vis spectrophotometer, Fourier transform infrared spectroscopy, powder X-ray diffraction, Raman spectroscopy, thermogravimetric analysis, scanning electron microscopy and energy dispersive spectroscopy. Transmission electron microscopy reveals the effective anchoring of QDs on f-MWCNTs. The catalytic activity of nanocatalysts was evaluated by photodegradation of methyl orange under illumination of UV light. The coupling of MWCNTs, PAMAM and CdS or Ag2S QDs significantly enhanced the catalytic efficiency of nanocatalysts. The rate constants for degradation of methyl orange in presence of nanocatalysts were calculated using the Langmuir-Hinshelwood model. Overall, the excellence in photodegradation was accomplished by hybridizing f-MWCNTs with CdS or Ag2S PMID:22267895

Biodegradable multilayer barrier films based on alginate/polyethyleneimine and biaxially oriented poly(lactic acid).

PubMed

Gu, Chun-Hong; Wang, Jia-Jun; Yu, Yang; Sun, Hui; Shuai, Ning; Wei, Bing

2013-02-15

A layer-by-layer (LBL) approach was used to assemble alternating layers of sodium alginate (ALG)/polyethyleneimine (PEI) on biaxially oriented poly(lactic acid) (BOPLA) films in order to produce bio-based all-polymer thin films with low gas permeability. Increasing the depositing of ALG and PEI from 0 to 30 layers results in large thickness variations (from 0 to 3.92 μm). After 30 ALG/PEI layers are deposited, the resulting assembly has an OTR of 1.22 cm(3)/(m(2) day atm). When multiplied by thickness, the resulting oxygen permeability (OP) is found to be less than 3.8×10(-17) cm(3) cm/cm(2) s Pa, which is almost 3 orders of magnitude lower than that of uncoated BOPLA film (1.8×10(-14) cm(3)cm/cm(2) s Pa). At the same time, the resulting multilayer-coated BOPLA films maintain high optical clarity and tensile properties. This unique barrier thin film has become a promising alternative to non-biodegradable synthetic food packaging materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

Preparation of bimetallic Cu-Co nanocatalysts on poly (diallyldimethylammonium chloride) functionalized halloysite nanotubes for hydrolytic dehydrogenation of ammonia borane

NASA Astrophysics Data System (ADS)

Liu, Yang; Zhang, Jun; Guan, Huijuan; Zhao, Yafei; Yang, Jing-He; Zhang, Bing

2018-01-01

In present work, we prepared the bimetallic Cu-Co nanocatalysts on poly (diallyldimethylammonium chloride) functionalized halloysite nanotubes (Cu-Co/PDDA-HNTs) by a deposition-reduction technique at room temperature. The analysis of XRD, SEM, TEM, HAADF-STEM and XPS were employed to systematically investigate the morphology, particle size, structure and surface properties of the nanocomposite. The results reveal that the PDDA coating with thickness of ∼15 nm could be formed on the surface of HNTs, and the existence of PDDA is beneficial to deposit Cu and Co nanoparticles (NPs) with high dispersibility on the surface. While the cost-effective nanocomposite was used for the hydrolytic dehydrogenation of ammonia-borane (NH3BH3), the nanocatalyst showed extraordinary catalytic properties with high total turnover frequency of 30.8 molH2/(molmetal min), low activation energy of 35.15 kJ mol-1 and high recycling stability (>90% conversion at 10th reuse). These results indicate that the bimetallic Cu-Co nanocatalysts on PDDA functionalized HNTs have particular potential for application in release hydrogen process.

Inhibiting surface crystallization of amorphous indomethacin by nanocoating.

PubMed

Wu, Tian; Sun, Ye; Li, Ning; de Villiers, Melgardt M; Yu, Lian

2007-04-24

An amorphous solid (glass) may crystallize faster at the surface than through the bulk, making surface crystallization a mechanism of failure for amorphous pharmaceuticals and other materials. An ultrathin coating of gold or polyelectrolytes inhibited the surface crystallization of amorphous indomethacin (IMC), an anti-inflammatory drug and model organic glass. The gold coating (10 nm) was deposited by sputtering, and the polyelectrolyte coating (3-20 nm) was deposited by an electrostatic layer-by-layer assembly of cationic poly(dimethyldiallyl ammonium chloride) (PDDA) and anionic sodium poly(styrenesulfonate) (PSS) in aqueous solution. The coating also inhibited the growth of existing crystals. The inhibition was strong even with one layer of PDDA. The polyelectrolyte coating still permitted fast dissolution of amorphous IMC and improved its wetting and flow. The finding supports the view that the surface crystallization of amorphous IMC is enabled by the mobility of a thin layer of surface molecules, and this mobility can be suppressed by a coating of only a few nanometers. This technique may be used to stabilize amorphous drugs prone to surface crystallization, with the aqueous coating process especially suitable for drugs of low aqueous solubility.

Poly(3-Methylthiophene) Thin Films Deposited Electrochemically on QCMs for the Sensing of Volatile Organic Compounds

PubMed Central

Öztürk, Sadullah; Kösemen, Arif; Şen, Zafer; Kılınç, Necmettin; Harbeck, Mika

2016-01-01

Poly(3-methylthiophene) (PMeT) thin films were electrochemically deposited on quartz crystal microbalance QCM transducers to investigate their volatile organic compound (VOC) sensing properties depending on ambient conditions. Twelve different VOCs including alcohols, ketones, chlorinated compounds, amines, and the organosphosphate dimethyl methylphosphonate (DMMP) were used as analytes. The responses of the chemical sensors against DMMP were the highest among the tested analytes; thus, fabricated chemical sensors based on PMeT can be evaluated as potential candidates for selectively detecting DMMP. Generally, detection limits in the low ppm range could be achieved. The gas sensing measurements were recorded at various humid air conditions to investigate the effects of the humidity on the gas sensing properties. The sensing performance of the chemical sensors was slightly reduced in the presence of humidity in ambient conditions. While a decrease in sensitivity was observed for humidity levels up to 50% r.h., the sensitivity was nearly unaffected for higher humidity levels and a reliable detection of the VOCs and DMMP was possible with detection limits in the low ppm range. PMID:27023539

Poly(3,4-ethylenedioxythiophene)/reduced graphene oxide composites as counter electrodes for high efficiency dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Ma, Jinfu; Yuan, Shenghua; Yang, Shaolin; Lu, Hui; Li, Yingtao

2018-05-01

A facile, low cost, easy-controllable method to prepare Poly(3,4-ethylenedioxythiophene) (PEDOT)/reduced graphene oxide (rGO) composites by electrochemical deposition onto fluorinated tin oxide (FTO) as counter electrodes (CEs) in high performance dye-sensitized solar cells (DSSCs) is reported. The electro-deposition process was accomplished by electro-polymerization of graphene oxide (GO)/PEDOT composites onto FTO substrates followed by electrochemical reduction of the GO component. Electrochemical measurements show that the I-/I3- catalytic activity of the as-prepared PEDOT/rGO CE is improved compared with that of the pure PEDOT and PEDOT/GO electrode. Through the analysis of photoelectric properties, the performance of the electrodes fabricated with different polymerization times are compared, and the optimal preparation condition is determined. The photoelectric conversion efficiency (PCE) of the DSSC assembled with PEDOT/rGO electrode reaches 7.79%, close to 8.33% of the cell with Platinum (Pt) electrode, and increases by 13.2% compared with 6.88% of the device with the PEDOT electrode.

Polymer-coated compliant receivers for intact laser-induced forward transfer of thin films: experimental results and modelling

NASA Astrophysics Data System (ADS)

Feinaeugle, Matthias; Horak, Peter; Sones, Collin L.; Lippert, Thomas; Eason, Rob W.

2014-09-01

In this study, we investigate both experimentally and numerically laser-induced forward transfer (LIFT) of thin films to determine the role of a thin polymer layer coating the receiver with the aim of modifying the rate of deceleration and reduction of material stress preventing intact material transfer. A numerical model of the impact phase during LIFT shows that such a layer reduces the modelled stress. The evolution of stress within the transferred deposit and the substrate as a function of the thickness of the polymer layer, the transfer velocity and the elastic properties of the polymer are evaluated. The functionality of the polymer layer is verified experimentally by LIFT printing intact 1- m-thick bismuth telluride films and polymeric light-emitting diode pads onto a layer of 12-m-thick polydimethylsiloxane and 50-nm-thick poly(3,4-ethylenedioxythiophene) blended with poly(styrenesulfonate) (PEDOT:PSS), respectively. Furthermore, it is demonstrated experimentally that the introduction of such a compliant layer improves adhesion between the deposit and its substrate.

Mechanics of hydrogenated amorphous carbon deposits from electron-beam-induced deposition of a paraffin precursor

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

Ding, W.; Dikin, D.A.; Chen, X.

2005-07-01

Many experiments on the mechanics of nanostructures require the creation of rigid clamps at specific locations. In this work, electron-beam-induced deposition (EBID) has been used to deposit carbon films that are similar to those that have recently been used for clamping nanostructures. The film deposition rate was accelerated by placing a paraffin source of hydrocarbon near the area where the EBID deposits were made. High-resolution transmission electron microscopy, electron-energy-loss spectroscopy, Raman spectroscopy, secondary-ion-mass spectrometry, and nanoindentation were used to characterize the chemical composition and the mechanics of the carbonaceous deposits. The typical EBID deposit was found to be hydrogenated amorphousmore » carbon (a-C:H) having more sp{sup 2}- than sp{sup 3}-bonded carbon. Nanoindentation tests revealed a hardness of {approx}4 GPa and an elastic modulus of 30-60 GPa, depending on the accelerating voltage. This reflects a relatively soft film, which is built out of precursor molecular ions impacting the growing surface layer with low energies. The use of such deposits as clamps for tensile tests of poly(acrylonitrile)-based carbon nanofibers loaded between opposing atomic force microscope cantilevers is presented as an example application.« less

Organic solar cells with graphene electrodes and vapor printed poly(3,4-ethylenedioxythiophene) as the hole transporting layers.

PubMed

Park, Hyesung; Howden, Rachel M; Barr, Miles C; Bulović, Vladimir; Gleason, Karen; Kong, Jing

2012-07-24

For the successful integration of graphene as a transparent conducting electrode in organic solar cells, proper energy level alignment at the interface between the graphene and the adjacent organic layer is critical. The role of a hole transporting layer (HTL) thus becomes more significant due to the generally lower work function of graphene compared to ITO. A commonly used HTL material with ITO anodes is poly(3,4-ethylenedioxythiophene) (PEDOT) with poly(styrenesulfonate) (PSS) as the solid-state dopant. However, graphene's hydrophobic surface renders uniform coverage of PEDOT:PSS (aqueous solution) by spin-casting very challenging. Here, we introduce a novel, yet simple, vapor printing method for creating patterned HTL PEDOT layers directly onto the graphene surface. Vapor printing represents the implementation of shadow masking in combination with oxidative chemical vapor deposition (oCVD). The oCVD method was developed for the formation of blanket (i.e., unpatterened) layers of pure PEDOT (i.e., no PSS) with systematically variable work function. In the unmasked regions, vapor printing produces complete, uniform, smooth layers of pure PEDOT over graphene. Graphene electrodes were synthesized under low-pressure chemical vapor deposition (LPCVD) using a copper catalyst. The use of another electron donor material, tetraphenyldibenzoperiflanthene, instead of copper phthalocyanine in the organic solar cells also improves the power conversion efficiency. With the vapor printed HTL, the devices using graphene electrodes yield comparable performances to the ITO reference devices (η(p,LPCVD) = 3.01%, and η(p,ITO) = 3.20%).

Quantitative Super-Resolution Microscopy of Nanopipette-Deposited Fluorescent Patterns.

PubMed

Hennig, Simon; van de Linde, Sebastian; Bergmann, Stephan; Huser, Thomas; Sauer, Markus

2015-08-25

We describe a method for the deposition of minute amounts of fluorophore-labeled oligonucleotides with high local precision in conductive and transparent solid layers of poly(vinyl alcohol) (PVA) doped with glycerin and cysteamine (PVA-G-C layers). Deposition of negatively charged fluorescent molecules was accomplished with a setup based on a scanning ion conductance microscope (SICM) using nanopipettes with tip diameters of ∼100 nm by using the ion flux flowing between two electrodes through the nanopipette. To investigate the precision of the local deposition process, we performed in situ super-resolution microscopy by direct stochastic optical reconstruction microscopy (dSTORM). Exploiting the single-molecule sensitivity and reliability of dSTORM, we determine the number of fluorescent molecules deposited in single spots. The correlation of applied charge and number of deposited molecules enables the quantification of delivered molecules by measuring the charge during the delivery process. We demonstrate the reproducible deposition of 3-168 fluorescent molecules in single spots and the creation of fluorescent structures. The fluorescent structures are highly stable and can be reused several times.

Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process

PubMed Central

Baumgärtner, Benjamin; Möller, Hendrik; Neumann, Thomas

2017-01-01

A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol–gel-processing of silica precursors is used to deposit a silica coating directly on the fiber’s surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine) via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine)) on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine), silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes. PMID:28685115

Nanoscale patterning of two metals on silicon surfaces using an ABC triblock copolymer template.

PubMed

Aizawa, Masato; Buriak, Jillian M

2006-05-03

Patterning technologically important semiconductor interfaces with nanoscale metal films is important for applications such as metallic interconnects and sensing applications. Self-assembling block copolymer templates are utilized to pattern an aqueous metal reduction reaction, galvanic displacement, on silicon surfaces. Utilization of a triblock copolymer monolayer film, polystyrene-block-poly(2-vinylpyridine)-block-poly(ethylene oxide) (PS-b-P2VP-b-PEO), with two blocks capable of selective transport of different metal complexes to the surface (PEO and P2VP), allows for chemical discrimination and nanoscale patterning. Different regions of the self-assembled structure discriminate between metal complexes at the silicon surface, at which time they undergo the spontaneous reaction at the interface. Gold deposition from gold(III) compounds such as HAuCl4(aq) in the presence of hydrofluoric acid mirrors the parent block copolymer core structure, whereas silver deposition from Ag(I) salts such as AgNO3(aq) does the opposite, localizing exclusively under the corona. By carrying out gold deposition first and silver second, sub-100-nm gold features surrounded by silver films can be produced. The chemical selectivity was extended to other metals, including copper, palladium, and platinum. The interfaces were characterized by a variety of methods, including scanning electron microscopy, scanning Auger microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy.

Preparation of thick silica coatings on carbon fibers with fine-structured silica nanotubes induced by a self-assembly process.

PubMed

Baumgärtner, Benjamin; Möller, Hendrik; Neumann, Thomas; Volkmer, Dirk

2017-01-01

A facile method to coat carbon fibers with a silica shell is presented in this work. By immobilizing linear polyamines on the carbon fiber surface, the high catalytic activity of polyamines in the sol-gel-processing of silica precursors is used to deposit a silica coating directly on the fiber's surface. The surface localization of the catalyst is achieved either by attaching short-chain polyamines (e.g., tetraethylenepentamine) via covalent bonds to the carbon fiber surface or by depositing long-chain polyamines (e.g., linear poly(ethylenimine)) on the carbon fiber by weak non-covalent bonding. The long-chain polyamine self-assembles onto the carbon fiber substrate in the form of nanoscopic crystallites, which serve as a template for the subsequent silica deposition. The silicification at close to neutral pH is spatially restricted to the localized polyamine and consequently to the fiber surface. In case of the linear poly(ethylenimine), silica shells of several micrometers in thickness can be obtained and their morphology is easily controlled by a considerable number of synthesis parameters. A unique feature is the hierarchical biomimetic structure of the silica coating which surrounds the embedded carbon fiber by fibrillar and interconnected silica fine-structures. The high surface area of the nanostructured composite fiber may be exploited for catalytic applications and adsorption purposes.

Polypeptide multilayer films on colloidal particles: an in situ electro-optical study.

PubMed

Radeva, Tsetska; Kamburova, Kamelia

2007-04-15

The buildup of poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) multilayers on beta-FeOOH colloidal particles was investigated by means of electro-optics and electrophoresis. The films were built at different (acidic) pH in the absence of salt. We found that the thickness of the film grows linearly when the fully charged PLL (at pH 5.5) is combined with almost fully charged PGA (at pH 6.5), with a thickness of about 2 nm per single layer. When the fully charged PLL is combined with weakly charged PGA (at pH 4.5), the film thickness increases exponentially with the number of deposited layers. The thickness of the exponentially growing film increases to 300 nm after deposition of 16 layers. The exponential film growth is attributed to the ability of the PLL to diffuse "in" and "out" of the film bulk at each deposition step. The variation in the electrical polarizability of the film-coated particles was also monitored as a function of the number of adsorbed layers. The result reveals that the PLL chains, which can diffuse into the film bulk, have no measurable contribution to the electro-optical effect of the films terminated with PLL. It is only due to the polarization of counterions of the PLL adsorbed on the film surface.

Photoinitiated chemical vapor deposition of cytocompatible poly(2-hydroxyethyl methacrylate) films.

PubMed

McMahon, Brian J; Pfluger, Courtney A; Sun, Bing; Ziemer, Katherine S; Burkey, Daniel D; Carrier, Rebecca L

2014-07-01

Poly(2-hydroxyethyl methacrylate) (pHEMA) is a widely utilized biomaterial due to lack of toxicity and suitable mechanical properties; conformal thin pHEMA films produced via chemical vapor deposition (CVD) would thus have broad biomedical applications. Thin films of pHEMA were deposited using photoinitiated CVD (piCVD). Incorporation of ethylene glycol diacrylate (EGDA) into the pHEMA polymer film as a crosslinker, confirmed via Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, resulted in varied swelling and degradation behavior. 2-Hydroxyethyl methacrylate-only films showed significant thickness loss (up to 40%), possibly due to extraction of low-molecular-weight species or erosion, after 24 h in aqueous solution, whereas films crosslinked with EGDA (9.25-12.4%) were stable for up to 21 days. These results differ significantly from those obtained with plasma-polymerized pHEMA, which degraded steadily over a 21-day period, even with crosslinking. This suggests that the piCVD films differ structurally from those fabricated via plasma polymerization (plasma-enhanced CVD). piCVD pHEMA coatings proved to be good cell culture materials, with Caco-2 cell attachment and viability comparable to results obtained on tissue-culture polystyrene. Thus, thin film CVD pHEMA offers the advantage of enabling conformal coating of a cell culture substrate with tunable properties depending on method of preparation and incorporation of crosslinking agents. © 2013 Wiley Periodicals, Inc.

Controlled growth of Au nanoparticles in co-evaporated metal/polymer composite films and their optical and electrical properties

NASA Astrophysics Data System (ADS)

Takele, H.; Schürmann, U.; Greve, H.; Paretkar, D.; Zaporojtchenko, V.; Faupel, F.

2006-02-01

Nanocomposite films containing Au nanoparticles embedded in a polymer matrix were prepared by vapour phase co-deposition of Au and polymers (Teflon AF and Poly(α -methylstyrene)) in high vacuum. The microstructure of the composite materials as well as metal content strongly depend on the condensation coefficient of the Au atoms, the deposition rates of the components, the substrate temperature, and the type of polymer matrix. The condensation coefficient, which varies between 0.03 and 1, was determined from energy dispersive X-ray spectrometer (EDX) and surface profilometry. It is shown that the microstructure of nanocomposites (size, size distribution, and interparticle separation of metal clusters), which was determined by transmission electron microscopy, can be controlled by the deposition parameters and the choice of polymer matrix. The optical absorption in the visible region due to the particle plasmon resonance has a strong dependence on the metal filling factor. The correlation between the microstructure of nanocomposites and optical properties, studied using UV-Vis spectroscopy, was also established. Further more, the electrical properties of the composites were studied as a function of the metal volume fraction. It was observed that the nanocomposite films exhibit a percolation threshold at a metal volume fraction of 0.43 and 0.20 for gold nanoclusters in Teflon AF and Poly(α-methylstyrene), respectively.

Self-organized pattern formation at organic-inorganic interfaces during deposition: Experiment versus modeling

NASA Astrophysics Data System (ADS)

Szillat, F.; Mayr, S. G.

2011-09-01

Self-organized pattern formation during physical vapor deposition of organic materials onto rough inorganic substrates is characterized by a complex morphological evolution as a function of film thickness. We employ a combined experimental-theoretical study using atomic force microscopy and numerically solved continuum rate equations to address morphological evolution in the model system: poly(bisphenol A carbonate) on polycrystalline Cu. As the key ingredients for pattern formation, (i) curvature and interface potential driven surface diffusion, (ii) deposition noise, and (iii) interface boundary effects are identified. Good agreement of experiments and theory, fitting only the Hamaker constant and diffusivity within narrow physical parameter windows, corroborates the underlying physics and paves the way for computer-assisted interface engineering.

Hybrid Organic/ZnO p-n Junctions with n-Type ZnO Grown by Atomic Layer Deposition

NASA Astrophysics Data System (ADS)

Łuka, G.; Krajewski, T.; Szczerbakow, A.; Łusakowska, E.; Kopalko, K.; Guziewicz, E.; Wachnicki, Ł.; Szczepanik, A.; Godlewski, M.; Fidelus, J. D.

2008-11-01

We report on fabrication of hybrid inorganic-on-organic thin film structures with polycrystalline zinc oxide films grown by atomic layer deposition technique. ZnO films were deposited on two kinds of thin organic films, i.e. pentacene and poly(dimethylosiloxane) elastomer with a carbon nanotube content (PDMS:CNT). Surface morphology as well as electrical measurements of the films and devices were analyzed. The current density versus voltage (I-V) characteristics of ITO/pentacene/ZnO/Au structure show a low-voltage switching phenomenon typical of organic memory elements. The I-V studies of ITO/PDMS:CNT/ZnO/Au structure indicate some charging effects in the system under applied voltages.

TiO2 Nanowires/Poly(Methyl Methacrylate) Based Hybrid Photodetector: Improved Light Detection.

PubMed

Saha, S; Mondal, A; Choudhur, B; Goswami, T; Sarkar, M B; Chattopadhyay, K K

2016-03-01

Hybrid photodetector with a maximum external quantum efficiency of ~3.08% in the UV region at 370 nm, was fabricated by spin-coated poly(methyl methacrylate) (PMMA) polymer onto glancing angle deposited (GLAD) vertically aligned TiO2 nanowire (NW) arrays. The TiO2 NWs/PMMA detector shows excellent rectification and constant 1.3 times photo-responsivity in the reverse bias condition from -1 V to -10 V. The photodiode possesses a low ideality factor of 5.1 as compared to bared TiO2 NWs device of 7.1. The hybrid device produces sharp turn-on of -0.8 s and turn-off transient of -0.9 s respectively.

Emotional Contagion is not Altered in Mice Prenatally Exposed to Poly (I:C) on Gestational Day 9.

PubMed

Gonzalez-Liencres, Cristina; Juckel, Georg; Esslinger, Manuela; Wachholz, Simone; Manitz, Marie-Pierre; Brüne, Martin; Friebe, Astrid

2016-01-01

Prenatal immune activation has been associated with increased risk of developing schizophrenia. The polyinosinic-polycytidylic acid (Poly(I:C)) mouse model replicates some of the endophenotype characteristic of this disorder but the social deficits observed in schizophrenia patients have not been well studied in this model. Therefore we aimed to investigate social behavior, in particular emotional contagion for pain, in this mouse model. We injected pregnant mouse dams with Poly(I:C) or saline (control) on gestation day 9 (GD9) and we evaluated their offspring in the pre-pulse inhibition (PPI) test at age 50-55 days old to confirm the reliability of our model. Mice were then evaluated in an emotional contagion test immediately followed by the light/dark test to explore post-test anxiety-like behavior at 10 weeks of age. In the emotional contagion test, an observer (prenatally exposed to Poly(I:C) or to saline) witnessed a familiar wild-type (WT) mouse (demonstrator) receiving electric foot shocks. Our results replicate the sensory gating impairments in the Poly(I:C) offspring but we only observed minor group differences in the social tasks. One of the differences we found was that demonstrators deposited fewer feces in the presence of control observers than of observers prenatally exposed to Poly(I:C), which we suggest could be due to the observers' behavior. We discuss the findings in the context of age, sex and day of prenatal injection, suggesting that Poly(I:C) on GD9 may be a valuable tool to assess other symptoms or symptom clusters of schizophrenia but perhaps not comprising the social domain.

Experimental study of three-dimensional fin-channel charge trapping flash memories with titanium nitride and polycrystalline silicon gates

NASA Astrophysics Data System (ADS)

Liu, Yongxun; Matsukawa, Takashi; Endo, Kazuhiko; O'uchi, Shinichi; Tsukada, Junichi; Yamauchi, Hiromi; Ishikawa, Yuki; Mizubayashi, Wataru; Morita, Yukinori; Migita, Shinji; Ota, Hiroyuki; Masahara, Meishoku

2014-01-01

Three-dimensional (3D) fin-channel charge trapping (CT) flash memories with different gate materials of physical-vapor-deposited (PVD) titanium nitride (TiN) and n+-polycrystalline silicon (poly-Si) have successfully been fabricated by using (100)-oriented silicon-on-insulator (SOI) wafers and orientation-dependent wet etching. Electrical characteristics of the fabricated flash memories including statistical threshold voltage (Vt) variability, endurance, and data retention have been comparatively investigated. It was experimentally found that a larger memory window and a deeper erase are obtained in PVD-TiN-gated metal-oxide-nitride-oxide-silicon (MONOS)-type flash memories than in poly-Si-gated poly-Si-oxide-nitride-oxide-silicon (SONOS)-type memories. The larger memory window and deeper erase of MONOS-type flash memories are contributed by the higher work function of the PVD-TiN metal gate than of the n+-poly-Si gate, which is effective for suppressing electron back tunneling during erase operation. It was also found that the initial Vt roll-off due to the short-channel effect (SCE) is directly related to the memory window roll-off when the gate length (Lg) is scaled down to 46 nm or less.

Comparative analysis of poly-glycolic acid-based hybrid polymer starter matrices for in vitro tissue engineering.

PubMed

Generali, Melanie; Kehl, Debora; Capulli, Andrew K; Parker, Kevin K; Hoerstrup, Simon P; Weber, Benedikt

2017-10-01

Biodegradable scaffold matrixes form the basis of any in vitro tissue engineering approach by acting as a temporary matrix for cell proliferation and extracellular matrix deposition until the scaffold is replaced by neo-tissue. In this context several synthetic polymers have been investigated, however a concise systematic comparative analyses is missing. Therefore, the present study systematically compares three frequently used polymers for the in vitro engineering of extracellular matrix based on poly-glycolic acid (PGA) under static as well as dynamic conditions. Ultra-structural analysis was used to examine the polymers structure. For tissue engineering (TE) three human fibroblast cell lines were seeded on either PGA-poly-4-hydroxybutyrate (P4HB), PGA-poly-lactic acid (PLA) or PGA-poly-caprolactone (PCL) patches. These patches were analyzed after 21days of culture qualitative by histology and quantitative by determining the amount of DNA, glycosaminoglycan and hydroxyproline. We found that PGA-P4HB and PGA-PLA scaffolds enhance tissue formation significantly higher than PGA-PCL scaffolds (p<0.05). Polymer remnants were visualized by polarization microscopy. In addition, biomechanical properties of the tissue engineered patches were determined in comparison to native tissue. This study may allow future studies to specifically select certain polymer starter matrices aiming at specific tissue properties of the bioengineered constructs in vitro. Copyright © 2017 Elsevier B.V. All rights reserved.

Vibrational spectroscopy in the ophthalmological field

NASA Astrophysics Data System (ADS)

Bertoluzza, Alessandro; Monti, P.; Simoni, R.

1991-05-01

Some applications of vibrational (Raman and FT/IR) spectroscopy to the study of biocompatibility in the ophthalmological field are described. The structure arid elastic properties of a new hydrophobic fluorocarbon copolymer (FCC) are presented. Bacterial adhesion on its surface is also considered. The structure arid properties of soft contact lenses based on poly2--hydroxyethylmethacrylate (PHEMA) and polyvinylpyrrolidone (PVP) are discussed in relation to their recent use as intrastromal implants. The preliminary results dealing with a study on protein deposits on soft contact lenses in presence of a collyrium limiting the formation of such deposits are also reported. 1.

Chromatographic evaluation of self-immobilized stationary phases for reversed-phase liquid chromatography.

PubMed

Bottoli, Carla B G; Collins, Kenneth E; Collins, Carol H

2003-02-14

The preparation of stationary phases for HPLC using polymers deposited on silica usually includes an immobilization step involving cross-linking by free radicals induced by ionizing radiation or by other radical initiators. The present paper reports changes which occur at ambient temperature in the character of poly(methyloctylsiloxane) deposited on porous silica particles as a function of the time interval between particle loading and column packing. Column performance and retention factors increase with time and these changes are attributed to rearrangement (self-assembly) which result in "self-immobilization" of the polymer molecules on the silica surface.

Formation of nanocrystalline SiGe in Polycrystalline-Ge/Si thin film without any metal induced crystallization

NASA Astrophysics Data System (ADS)

Tah, Twisha; Singh, Ch. Kishan; Madapu, K. K.; Polaki, S. R.; Ilango, S.; David, C.; Dash, S.; Panigrahi, B. K.

2017-05-01

The formation of nanocrystalline SiGe without the aid of metal induced crystallization is reported. Re-crystallization of the as-deposited poly-Ge film (deposited at 450 °C) leads to development of regions with depleted Ge concentration upon annealing at 500 °C. Clusters with crystalline facet containing both nanocrystalline SiGe and crystalline Ge phase starts appearing at 600 °C. The structural phase characteristics were investigated by X-ray diffraction (XRD) and Raman spectroscopy. The stoichiometry of the SiGe phase was estimated from the positions of the Raman spectral peaks.

Multilayer organic based structures with enhanced hole transport

NASA Astrophysics Data System (ADS)

Mladenova, D.; Sinigersky, V.; Budurova, D.; Dobreva, T.; Karashanova, D.; Dimov, D.; Zhivkov, I.

2010-11-01

Multilayer Organic Based Devices (OBDs) were constructed by subsequent casting of organic films (from polymers, soluble in the same organic solvent). The problem with dissolution of the underlying layer was avoided by using electrophoretic deposition technique. Optimized conditions for electrophoretic deposition (EPD) of thin films with homogeneous and smooth surfaces, as confirmed by SEM, were found. The EPD, carried out at constant current, requires continuous increase of the voltage between the electrodes. In this way the decreased deposition rate caused by the decreased concentration of the material in the suspension and the increased thickness of the film deposited is compensated. The SEM images and the current voltage characteristics recorded, show that the hole transport polyvinylcarbazole (PVK) underlayer survive the treatment with the suspension used for the electrophoretic deposition of the active poly[2-methoxy-5-(3,7-dimethyloctyloxy)-1,4-phenylene vinylene] electroluminescent layer. The PVK hole transport layer increases the device current, as confirmed by the current-voltage measurements. The results obtained demonstrate the possibility of OBDs preparation for electroluminescent and photovoltaic applications.

Effect of multiple deposition of NiO layer on the performance of inverted type organic solar cell based on ZnO/P3HT:PCBM

NASA Astrophysics Data System (ADS)

Sabri, Nasehah Syamin; Lim, Eng Liang; Yap, Chi Chin; Yahaya, Muhammad; Salleh, Muhamad Mat; Jumali, Mohammad Hafizuddin Haji

2017-05-01

In this work, the effect of multiple deposition of nickel oxide (NiO) hole transport layer (HTL) on the performance of inverted type organic solar cell with a configuration of fluorine tin oxide (FTO)/zinc oxide (ZnO) nanorods/ poly(3-hexylthiopene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM)/NiO/silver (Ag) was investigated. The NiO nanoparticles solution was spin-coated on top of the photoactive layer (P3HT:PCBM) prior to deposition of Ag electrode. Different numbers of NiO layers (1, 2, and 4) were deposited on the photoactive layer to obtain the optimum surface morphology of HTL. The device with 2 layers of NiO exhibited the optimum power conversion efficiency of 1.10%. It is believed that the optimum NiO deposition layer gives the complete coverage at photoactive layer and forms ohmic contact between the photoactive layer and Ag electrode.

Effects of P3HT concentration on the electrical properties of the Au/PEDOT:PSS/P3HT/n-GaN hybrid junction structure

NASA Astrophysics Data System (ADS)

Noh, Ji-yeon; Lee, Ha Young; Lim, Kyung-won; Ahn, Hyung Soo; Yi, Sam Nyung; Jeon, Hunsoo; Shin, Min Jeong; Yu, Young Moon; Ha, Dong Han

2017-09-01

An inorganic-organic hybrid junction has been fabricated by spin coating the p-type poly(3- hexylthiophene-2,5-diyl)(P3HT) and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT: PSS) on an n-type GaN layer. The GaN layer was formed on Al2O3 by metal organic chemical vapor deposition(MOCVD) method. To investigate the effects of P3HT concentration on the electrical properties, we changed P3HT solution concentration and speed of spin coater. The currentvoltage (I-V ) characteristic of Au/PEDOT:PSS/P3HT/n-GaN shows rectifying behavior. The I-V characteristic was examined in the frame work of the thermionic emission model. The most proper rectifying behavior was obtained for 0.6 wt% and thickness below 65 nm of P3HT used diode. We expect that such hybrid structures, suitably developed, might be enable the fabrication of highquality electronic and optoelectronic devices.

Multilayer polymer light-emitting diodes by blade coating method

NASA Astrophysics Data System (ADS)

Tseng, Shin-Rong; Meng, Hsin-Fei; Lee, Kuan-Chen; Horng, Sheng-Fu

2008-10-01

Multilayer polymer light-emitting diodes fabricated by blade coating are presented. Multilayer of polymers can be easily deposited by blade coating on a hot plate. The multilayer structure is confirmed by the total thickness and the cross section view in the scanning electron microscope. The film thickness variation is only 3.3% in 10cm scale and the film roughness is about 0.3nm in the micron scale. The efficiency of single layer poly(para-phenylene vinylene) copolymer Super Yellow and poly(9,9-dioctylfluorene) (PFO, deep blue) devices are 9 and 1.7cd/A, respectively, by blade coating. The efficiency of the PFO device is raised to 2.9cd/A with a 2-(4-tert-butylphenyl)-5-(4-biphenylyl)-1,3,4-oxadiazole (PBD) hole-blocking layer and to 2.3cd/A with a poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] elec-tron-blocking layer added by blade coating.

Electrical doping of poly(9,9-dioctylfluorenyl-2,7-diyl) with tetrafluorotetracyanoquinodimethane by solution method

NASA Astrophysics Data System (ADS)

Hwang, Jaehyung; Kahn, Antoine

2005-05-01

We investigate p-type doping of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) films with tetrafluorotetracyanoquinodimethane (F4-TCNQ) introduced via cosolution. Doped and undoped films are compared using ultraviolet photoelectron spectroscopy (UPS) and current-voltage (I-V) measurement. In spite of the difference between the ionization energy of PFO (5.8 eV) and the electron affinity of F4-TCNQ (5.24 eV), p doping occurs, as seen from the movement of the Fermi level (EF) toward the polymer highest occupied molecular orbital (HOMO). Interface hole barriers are measured for undoped and doped PFO deposited on three substrates with different work functions, indium-tin-oxide (ITO), gold (Au), and poly-3,4-ethylenedioxythiophene•polystyrenesulfonate (PEDOT•PSS). Doping leads to the formation of a depletion region at the PFO/ITO and PFO /Au interfaces. The depletion region is believed to be at the origin of the (hole) current enhancement observed on simple metal/PFO/substrate devices.

Atovaquone-loaded nanocapsules: influence of the nature of the polymer on their in vitro characteristics.

PubMed

Cauchetier, Emmanuelle; Deniau, M; Fessi, H; Astier, A; Paul, M

2003-01-02

Nanocapsules with atovaquone concentration of 1,000 micrograms/ml were prepared according to the interfacial deposition technique using different polymers: poly- epsilon -caprolactone (PECL), poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLAGA). The following characteristics of nanoparticles were determined: percentage of encapsulation of atovaquone, percentage of encapsulation of benzyl benzoate (BB), nanoparticle size, nanoparticle wall thickness, suspension pH, and in vitro stability. The different formulations showed similar characteristics: maximal percentage of encapsulation (100%), particle size of approximately 230 nm, neutral pH and wall thickness of approximately 20 nm. The type of polymer used was the main factor influencing stability, in decreasing order: PECL>PLA>PLAGA. No release of atovaquone or benzylbenzoate was noted with PECL nanoparticles over 4 months. Release of atovaquone (25.9%) was found with PLA nanoparticles at 4 months. Release of both atovaquone (18.9%) and benzylbenzoate (54.2%) was noted with PLAGA nanoparticles from the third month, indicating a disruption of the nanoparticle membrane.

Preparation of K+-Doped Core-Shell NaYF4:Yb, Er Upconversion Nanoparticles and its Application for Fluorescence Immunochromatographic Assay of Human Procalcitonin.

PubMed

Tang, Jie; Lei, Lijiang; Feng, Hui; Zhang, Hongman; Han, Yuwang

2016-11-01

In the present study, we reported a convenient route to prepare well dispersed and functionalized K + -doped core-shell upconversion nanoparticles (UCP) by layer-by-layer (LbL) assembly of polyelectrolytes. UCP was firstly transferred to aqueous phase using cationic surfactant cetyl trimethyl ammonium bromide (CTAB) via hydrophobic interaction without removing the existing oleic acid (OA). Then the positively charged hydrophilic UCP@CTAB was further alternately deposited with negatively charged [poly (sodium 4-styrenesulfonate)] (PSS), positively charged [poly (allylamine hydrochloride)] (PAH) and negatively charged [poly (acrylic acid)] (PAA). The final carboxyl functionalized UCP@CTAB@PSS@PAH@PAA was then conjugated with monoclonal antibody1 (AB1) of procalcitonin (PCT), resulting in successful detection of PCT antigens based on the immunochromatographic assay (ICA). Linear response was achieved from 0 to 10 ng/mL, and the lowest limit of detection (LLD) was 0.18 ng/mL.

Fabrication of high performance thin-film transistors via pressure-induced nucleation.

PubMed

Kang, Myung-Koo; Kim, Si Joon; Kim, Hyun Jae

2014-10-31

We report a method to improve the performance of polycrystalline Si (poly-Si) thin-film transistors (TFTs) via pressure-induced nucleation (PIN). During the PIN process, spatial variation in the local solidification temperature occurs because of a non-uniform pressure distribution during laser irradiation of the amorphous Si layer, which is capped with an SiO2 layer. This leads to a four-fold increase in the grain size of the poly-Si thin-films formed using the PIN process, compared with those formed using conventional excimer laser annealing. We find that thin films with optimal electrical properties can be achieved with a reduction in the number of laser irradiations from 20 to 6, as well as the preservation of the interface between the poly-Si and the SiO2 gate insulator. This interface preservation becomes possible to remove the cleaning process prior to gate insulator deposition, and we report devices with a field-effect mobility greater than 160 cm(2)/Vs.

Enhanced bone formation in electrospun poly(L-lactic-co-glycolic acid)-tussah silk fibroin ultrafine nanofiber scaffolds incorporated with graphene oxide.

PubMed

Shao, Weili; He, Jianxin; Sang, Feng; Wang, Qian; Chen, Li; Cui, Shizhong; Ding, Bin

2016-05-01

To engineer bone tissue, it is necessary to provide a biocompatible, mechanically robust scaffold. In this study, we fabricated an ultrafine nanofiber scaffold by electrospinning a blend of poly(L-lactic-co-glycolic acid), tussah silk fibroin, and graphene oxide (GO) and characterized its morphology, biocompatibility, mechanical properties, and biological activity. The data indicate that incorporation of 10 wt.% tussah silk and 1 wt.% graphene oxide into poly(L-lactic-co-glycolic acid) nanofibers significantly decreased the fiber diameter from 280 to 130 nm. Furthermore, tussah silk and graphene oxide boosted the Young's modulus and tensile strength by nearly 4-fold and 3-fold, respectively, and significantly enhanced adhesion, proliferation in mouse mesenchymal stem cells and functionally promoted biomineralization-relevant alkaline phosphatase (ALP) and mineral deposition. The results indicate that composite nanofibers could be excellent and versatile scaffolds for bone tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

Laser-Induced Periodic Surface Structures on P3HT and on Its Photovoltaic Blend with PC71BM.

PubMed

Cui, Jing; Rodríguez-Rodríguez, Álvaro; Hernández, Margarita; García-Gutiérrez, Mari-Cruz; Nogales, Aurora; Castillejo, Marta; Moseguí González, Daniel; Müller-Buschbaum, Peter; Ezquerra, Tiberio A; Rebollar, Esther

2016-11-23

We describe the conditions for optimal formation of laser-induced periodic surface structures (LIPSS) over poly(3-hexylthiophene) (P3HT) spin-coated films. Optimal LIPSS on P3HT are observed within a particular range of thicknesses and laser fluences. These conditions can be translated to the photovoltaic blend formed by the 1:1 mixture of P3HT and [6,6]-phenyl C 71 -butyric acid methyl ester (PC 71 BM) when deposited on an indium tin oxide (ITO) electrode coated with (poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS). Solar cells formed by using either a bilayer of P3HT structured by LIPSS covered by PC 71 BM or a bulk heterojunction with a P3HT:PC 71 BM blend structured by LIPSS exhibit generation of electrical photocurrent under light illumination. These results suggest that LIPSS could be a compatible technology with organic photovoltaic devices.

Stimulated emission within the exciplex band by plasmonic-nanostructured polymeric heterojunctions

NASA Astrophysics Data System (ADS)

Zhang, Xinping; Li, Hongwei; Wang, Yimeng; Liu, Feifei

2015-03-01

Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix.Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr00140d

A star-shaped poly(2-methyl-2-oxazoline)-based antifouling coating: Application in investigation of the interaction between acetaminophen and bovine serum albumin by frontal analysis capillary electrophoresis.

PubMed

Du, Haiqin; Zhang, Chong; Mao, Ke; Wang, Yanmei

2017-08-01

In this work, an antifouling capillary modified with star-shaped poly(2-methyl-2-oxazoline)-based copolymer was used to study the interaction between acetaminophen (APAP) and bovine serum albumin (BSA) by frontal analysis capillary electrophoresis (FACE). The star-shaped copolymer, poly(ethylene imine)-graft-poly(2-methyl-2-oxazoline) (PEI-g-PMOXA), was immobilized onto the fused-silica capillary inner wall via dopamine-assisted co-deposition strategy, yielding a PEI-g-PMOXA/polydopamine (PDA)-coated antifouling capillary, i.e., an antifouling capillary coated with the PEI-g-PMOXA/PDA co-deposited film. Electroosmotic flow (EOF) mobility of the PEI-g-PMOXA/PDA-coated capillary was almost zero in a wide pH range (3.0-10.0), while the EOF mobility of bare capillary was much larger and increased significantly with pH increasing. When the PEI-g-PMOXA/PDA-coated capillary was exploited to separate a protein mixture including cytochrome c, lysozyme, ribonuclease A and α-chymotrypsinogen A, the theoretical plate numbers were of five orders of magnitude which were about ten-fold higher over those obtained with bare capillary; in addition, the RSD values of migration time were mostly less than 0.7% (30 consecutive runs) which were much smaller than those of bare capillary (c.a. 5.7%). The protein-resistant PEI-g-PMOXA/PDA-coated capillary was then used to investigate the interaction between APAP and BSA by FACE, the binding constant and number of binding sites at 25°C and pH 7.4 (Tris/HCl buffer of 25mM) were 1.39×10 4 M -1 and 1.08, respectively, which were comparable to the results determined by fluorescence spectroscopic measurement (3.18×10 4 M -1 and 1.19, respectively). Copyright © 2017 Elsevier B.V. All rights reserved.

Flexible resistive switching device based on poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(4-vinylphenol) (PVP) composite and methyl red heterojunction

NASA Astrophysics Data System (ADS)

Hassan, Gul; Ali, Shawkat; Bae, Jinho; Lee, Chong Hyun

2017-04-01

To obtain a desired performance of non-volatile memory applications, heterojunction-based resistive switching devices have tremendous attractions. In this paper, we demonstrate resistive switching characteristics for heterojunction of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/poly(4-vinylphenol) (PVP) composite and methyl red sandwiched in between bottom and top silver (Ag) electrodes. The proposed heterojunction layers are fabricated through spin coater at 3000 rpm for 60 s each, and the Ag electrodes are deposited through a commercialized inkjet printer DMP-3000 on polyethyleneterephthalate (PET) substrate. To verify the proposed device, the resistive switching on dual polarity voltage of ±10.2 V is measured over more than 500 endurance cycles. The paper also presents an R off/ R on ratio which can adjust through an active layer's area and a blending ratio of the PEDOT:PSS and PVP. By applying the area of 100 μm2 and the blending ratio of 3:1, we achieve the higher R off/ R on ratio of 121, and its high resistance state (HRS) and low resistance state (LRS) are observed as 3000 kΩ and 24.7 kΩ, respectively. To maintain a long retention time, the device is encapsulated with PDMS, which changes a little variations of 52 Ω for HRS 498 Ω for LRS over 60 days. For the flexible realization to be utilized in wearable applications, it can be easily applied on a plastic substrate using printed technologies.

Effects of silicon nanowire morphology on optical properties and hybrid solar cell performance

NASA Astrophysics Data System (ADS)

Syu, Hong-Jhang; Shiu, Shu-Chia; Hung, Yung-Jr; Lee, San-Liang; Lin, Ching-Fuh

2012-10-01

Silicon nanowire (SiNW) arrays are widespread applied on hybrid photovoltaic devices because SiNW arrays can substitute the pyramid texture and anti-reflection coating due to its strong light trapping. Also, SiNWs can be prepared through a cost-efficient process of metal-assisted chemical etching. However, though longer SiNW arrays have lower reflectance, the top of long SiNWs aggregate together to make junction synthesis difficult for SiNW/organic hybrid solar cell. To control and analyze the effect of SiNW array morphology on hybrid solar cells, here we change the metal deposition condition for metal-assisted chemical etching to obtain different SiNW array morphologies. The experiment was separated to two groups, by depositing metal, say, Ag, before etching (BE) or during etching (DE). For group BE, Ag was deposited on n-type Si (n-Si) wafers by thermal evaporation; then etched by H2O2 and HF. For group DE, n-Si was etched by Ag+ and HF directly. Ag was deposited on n-Si during etching process. Afterwards, residual Ag and SiO2 were removed by HNO3 and buffered HF, successively; then Ti and Ag were evaporated on the bottom of Si to be a cathode. Finally, SiNWs were stuck on the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) that was spincoated on the ITO coated glass to form SiNW/organic heterojunction. The results show that group BE has reflectance lower than that in group DE in solar spectrum. However, group BE has smaller power conversion efficiency (PCE) of 8.65% and short-circuit current density (Jsc) of 24.94 mA/cm2 than group DE of PCE of 9.47% and Jsc of 26.81 mA/cm2.

Solid freeform fabrication and in-vitro response of osteoblast cells of mPEG-PCL-mPEG bone scaffolds.

PubMed

Jiang, Cho-Pei; Chen, Yo-Yu; Hsieh, Ming-Fa; Lee, Hung-Maan

2013-04-01

Bone tissue engineering is an emerging approach to provide viable substitutes for bone regeneration. Poly(ethylene glycol) (PEG) is a good candidate of bone scaffold because of several advantages such as hydrophilicity, biocompatibility, and intrinsic resistance to protein adsorption and cell adhesion. However, its low compressive strength limits application for bone regeneration. Poly(ε-caprolactone) (PCL), a hydrophobic nonionic polymer, is adopted to enhance the compressive strength of PEG alone.We aimed to investigate the in-vitro response of osteoblast-like cells cultured with porous scaffolds of triblock PEG-PCL-PEG copolymer fabricated by an air pressure-aided deposition system. A desktop air pressure-aided deposition system that involves melting and plotting PEG-PCL-PEG was used to fabricate three-dimensional scaffolds having rectangular pores. The experimental results showed that PEG-PCL-PEG with a molecular weight of 25,000 can be melted and stably deposited through a heating nozzle at an air pressure of 0.3 MPa and no crack occurs after it solidifies. The scaffolds with pre-determined pore size of 400× 420 μm and a porosity of 79 % were fabricated, and their average compressive strength was found to be 18.2 MPa. Osteoblast-like cells, MC3T3-E1, were seeded on fabricated scaffolds to investigate the in-vitro response of cells including toxicity and cellular locomotion. In a culture period of 28 days, the neutral-red stained osteoblasts were found to well distributed in the interior of the scaffold. Furthermore, the cellular attachment and movement in the first 10 h of cell culture were observed with time-lapse microscopy indicating that the porous PEG-PCL-PEG scaffolds fabricated by air pressure-aided deposition system is non-toxicity for osteoblast-like cells.

Lift-off process with bi-layer photoresist patterns for conformal-coated superhydrophilic pulsed plasma chemical vapor deposition-SiOx on SiCx for lab-on-a-chip applications

NASA Astrophysics Data System (ADS)

Konishi, Satoshi; Nakagami, Chise; Kobayashi, Taizo; Tonomura, Wataru; Kaizuma, Yoshihiro

2015-04-01

In this work, a lift-off process with bi-layer photoresist patterns was applied to the formation of hydrophobic/hydrophilic micropatterns on practical polymer substrates used in healthcare diagnostic commercial products. The bi-layer photoresist patterns with undercut structures made it possible to peel the conformal-coated silicon oxide (SiOx) films from substrates. SiOx and silicon carbide (SiCx) layers were deposited by pulsed plasma chemical vapor deposition (PPCVD) method which can form roughened surfaces to enhance hydrophilicity of SiOx and hydrophobicity of SiCx. Microfluidic applications using hydrophobic/hydrophilic patterns were also demonstrated on low-cost substrates such as poly(ethylene terephthalate) (PET) and paper films.

The effect of Be and Cr electrode deposition rate on the performance of MIS solar cells

NASA Astrophysics Data System (ADS)

Moharram, A. H.; Panayotatos, P.; Yeh, J. L.; Lalevic, B.

1985-07-01

An experimental study has been performed on MIS solar cells with Be, Cr and layered Cr-Be electrodes on single crystal Si, Wacker and Monsanto poly-Si substrates. Electrical characterization in the dark and under illumination was correlated to X-ray and Auger spectroscopy results. It was found that the electrode deposition rate directly affects the oxygen content of the electrodes for all metal-substrate configurations. This oxygen is believed to originate from the deposition ambient as well as from the SiO2 layer. In the case of cells with Cr and layered Cr-Be electrodes oxygen acts to reduce the electrode work function (thus increasing the open-circuit voltage) in direct proportion to the relative content of oxygen to chromium.

Copper cladding on polymer surfaces by ionization-assisted deposition

NASA Astrophysics Data System (ADS)

Kohno, Tomoki; Tanaka, Kuniaki; Usui, Hiroaki

2018-03-01

Copper thin films were prepared on poly(ethylene terephthalate) (PET) and polyimide (PI) substrates by an ionization-assisted vapor deposition method. The films had a polycrystalline structure, and their crystallite size decreased with increasing ion acceleration voltage V a. Ion acceleration was effective in reducing the surface roughness of the films. Cross-sectional transmission electron microscopy revealed that the copper/polymer interface showed increased corrugation with increasing V a. The increase in V a also induced the chemical modification of polymer chains of the PET substrate, but the PI substrate underwent smaller modification after ion bombardment. Most importantly, the adhesion strength between the copper film and the PET substrate increased with increasing V a. It was concluded that ionization-assisted deposition is a promising technique for preparing metal clad layers on flexible polymer substrates.

Optical and structural properties of cadmium telluride films grown by glancing angle deposition

NASA Astrophysics Data System (ADS)

Ehsani, M. H.; Rezagholipour Dizaji, H.; Azizi, S.; Ghavami Mirmahalle, S. F.; Siyanaki, F. Hosseini

2013-08-01

Cadmium telluride films were grown by the glancing angle deposition (GLAD) technique. The samples were prepared under different incident deposition flux angles (α = 0°, 20° and 70° measured from the normal to the substrate surface). During deposition, the substrate temperature was maintained at room temperature. The structural study was performed using an x-ray diffraction diffractometer. The samples were found to be poly-crystalline with cubic structure for those deposited at α = 0° and 20° and hexagonal structure for the one deposited at 70°. The images of samples obtained by the field emission scanning electron microscopy technique showed that the GLAD method could produce a columnar layer tilted toward the incident deposition flux. The optical properties study by the UV-Vis spectroscopy technique showed that the use of this growth technique affected the optical properties of the films. A higher absorption coefficient in the visible and near-IR spectral range was observed for the sample deposited at α = 70°. This is an important result from the photovoltaic applications point of view where absorber materials with large absorption coefficients are needed. Also, it seems that the sample with a high incident deposition flux angle has the capability of making an n-CdTe/p-CdTe homo-junction.

Block Copolymer as a Surface Modifier to Monodisperse Patchy Silica Nanoparticles for Superhydrophobic Surfaces.

PubMed

Lou, Shuo; Wang, Junzheng; Yin, Xiaohong; Qu, Wenxiu; Song, Yuexiao; Xin, Feng; Qaraah, Fahim Abdo Ali

2018-06-18

Monodisperse patchy silica nanoparticles (PSNPs) less than 100 nm are prepared based on the seed-regrowth method using a poly(ethylene oxide) (PEO)-poly(propylene oxide) (PPO)-PEO-type block copolymer as a surface modifier. Well-defined patches are controllably synthesized through area-selective deposition of silica onto the surface of seeds. After colloidal PSNPs are further modified with trimethylchlorosilane, the advancing and receding contact angles of water for PSNPs are 168 ± 2° and 167 ± 2°, respectively. The superhydrophobic and transparent coatings on the various types of substrates are obtained by a simple drop-casting procedure. Additionally, almost the same superhydrophobicity can be achieved by using colloidal PSNPs via redispersing the powder of superhydrophobic PSNPs in ethanol.

Self-immobilization of poly(methyloctylsiloxane) on high-performance liquid chromatographic silica.

PubMed

Collins, Kenneth E; Bottoli, Carla B G; Vigna, Camila R M; Bachmann, Stefan; Albert, Klaus; Collins, Carol H

2004-03-12

Poly(methyloctylsiloxane) (PMOS) was deposited on HPLC silica by a solvent evaporation procedure and this material was then extracted, using a good solvent for the PMOS, after different time periods, to remove unretained liquid polymer. Solvent extraction data reveal changes which occur at ambient temperature as a function of the time interval between particle loading and extraction. The quantity of PMOS remaining on the silica after extraction, as determined by elemental analysis for carbon, is attributed to strongly adsorbed polymer. This phenomenon is termed self-immobilization. Solid-state 29Si NMR spectra indicate the formation of a silicon species with a different chemical shift than the original PMOS. These new signals are attributed to a combination of different adsorbed and chemically bonded groups.

Raman scattering and anti-Stokes luminescence in poly-paraphenylene vinylene/carbon nanotubes composites

NASA Astrophysics Data System (ADS)

Baibarac, M.; Massuyeau, F.; Wery, J.; Baltog, I.; Lefrant, S.

2012-04-01

In this paper, we present Raman scattering and luminescence of poly-paraphenylene vinylene/single-walled carbon nanotubes composites, focused on data recorded in the anti-Stokes branch. We demonstrate that, when the excitation energy is in the long wavelength tail of the fundamental absorption edge, an anti-Stokes signal is generated, whose origin is a photon absorption accompanied by a phonon process from lower to upper vibronic states. The efficiency of this anti-Stokes photo-luminescence is increased when composites films are deposited onto an Au rough surface acting as a surface enhanced Raman scattering substrate. This mechanism is explained by a coherent anti-Stokes Raman scattering-like process, as observed in other nano-structured materials.

Evaluation of adhesive-free crossed-electrode poly(vinylidene fluoride) copolymer array transducers for high frequency imaging

NASA Astrophysics Data System (ADS)

Wagle, Sanat; Decharat, Adit; Habib, Anowarul; Ahluwalia, Balpreet S.; Melandsø, Frank

2016-07-01

High frequency crossed-electrode transducers have been investigated, both as single and dual layer transducers. Prototypes of these transducers were developed for 4 crossed lines (yielding 16 square elements) on a polymer substrate, using a layer-by-layer deposition method for poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] with intermediate sputtered electrodes. The transducer was characterized using various methods [LCR analyzer, a pulse-echo experimental setup, and a numerical Finite element method (FEM) model] and evaluated in terms of uniformity of bandwidth and acoustical energy output. All 16 transducer elements produced broad-banded ultrasonic spectra with small variation in central frequency and -6 dB bandwidth. The frequency responses obtained experimentally were verified using a numerical model.

Layered solid sorbents for carbon dioxide capture

DOEpatents

Li, Bingyun; Jiang, Bingbing; Gray, McMahan L; Fauth, Daniel J; Pennline, Henry W; Richards, George A

2013-02-25

A solid sorbent for the capture and the transport of carbon dioxide gas is provided having at least one first layer of a positively charged material that is polyethylenimine or poly(allylamine hydrochloride), that captures at least a portion of the gas, and at least one second layer of a negatively charged material that is polystyrenesulfonate or poly(acryclic acid), that transports the gas, wherein the second layer of material is in juxtaposition to, attached to, or crosslinked with the first layer for forming at least one bilayer, and a solid substrate support having a porous surface, wherein one or more of the bilayers is/are deposited on the surface of and/or within the solid substrate. A method of preparing and using the solid sorbent is provided.

Layered solid sorbents for carbon dioxide capture

DOEpatents

Li, Bingyun; Jiang, Bingbing; Gray, McMahan L; Fauth, Daniel J; Pennline, Henry W; Richards, George A

2014-11-18

A solid sorbent for the capture and the transport of carbon dioxide gas is provided having at least one first layer of a positively charged material that is polyethylenimine or poly(allylamine hydrochloride), that captures at least a portion of the gas, and at least one second layer of a negatively charged material that is polystyrenesulfonate or poly(acryclic acid), that transports the gas, wherein the second layer of material is in juxtaposition to, attached to, or crosslinked with the first layer for forming at least one bilayer, and a solid substrate support having a porous surface, wherein one or more of the bilayers is/are deposited on the surface of and/or within the solid substrate. A method of preparing and using the solid sorbent is provided.

Diamond detectors for high energy physics experiments

NASA Astrophysics Data System (ADS)

Bäni, L.; Alexopoulos, A.; Artuso, M.; Bachmair, F.; Bartosik, M.; Beacham, J.; Beck, H.; Bellini, V.; Belyaev, V.; Bentele, B.; Berdermann, E.; Bergonzo, P.; Bes, A.; Brom, J.-M.; Bruzzi, M.; Cerv, M.; Chiodini, G.; Chren, D.; Cindro, V.; Claus, G.; Collot, J.; Cumalat, J.; Dabrowski, A.; D'Alessandro, R.; Dauvergne, D.; de Boer, W.; Dorfer, C.; Dünser, M.; Eremin, V.; Eusebi, R.; Forcolin, G.; Forneris, J.; Frais-Kölbl, H.; Gallin-Martel, L.; Gallin-Martel, M. L.; Gan, K. K.; Gastal, M.; Giroletti, C.; Goffe, M.; Goldstein, J.; Golubev, A.; Gorišek, A.; Grigoriev, E.; Grosse-Knetter, J.; Grummer, A.; Gui, B.; Guthoff, M.; Haughton, I.; Hiti, B.; Hits, D.; Hoeferkamp, M.; Hofmann, T.; Hosslet, J.; Hostachy, J.-Y.; Hügging, F.; Hutton, C.; Jansen, H.; Janssen, J.; Kagan, H.; Kanxheri, K.; Kasieczka, G.; Kass, R.; Kassel, F.; Kis, M.; Konovalov, V.; Kramberger, G.; Kuleshov, S.; Lacoste, A.; Lagomarsino, S.; Lo Giudice, A.; Lukosi, E.; Maazouzi, C.; Mandic, I.; Mathieu, C.; Menichelli, M.; Mikuž, M.; Morozzi, A.; Moss, J.; Mountain, R.; Murphy, S.; Muškinja, M.; Oh, A.; Oliviero, P.; Passeri, D.; Pernegger, H.; Perrino, R.; Picollo, F.; Pomorski, M.; Potenza, R.; Quadt, A.; Re, A.; Reichmann, M.; Riley, G.; Roe, S.; Sanz, D.; Scaringella, M.; Schaefer, D.; Schmidt, C. J.; Schnetzer, S.; Sciortino, S.; Scorzoni, A.; Seidel, S.; Servoli, L.; Smith, S.; Sopko, B.; Sopko, V.; Spagnolo, S.; Spanier, S.; Stenson, K.; Stone, R.; Sutera, C.; Tannenwald, B.; Taylor, A.; Traeger, M.; Tromson, D.; Trischuk, W.; Tuve, C.; Uplegger, L.; Velthuis, J.; Venturi, N.; Vittone, E.; Wagner, S.; Wallny, R.; Wang, J. C.; Weingarten, J.; Weiss, C.; Wengler, T.; Wermes, N.; Yamouni, M.; Zavrtanik, M.

2018-01-01

Beam test results of the radiation tolerance study of chemical vapour deposition (CVD) diamond against different particle species and energies is presented. We also present beam test results on the independence of signal size on incident particle rate in charged particle detectors based on un-irradiated and irradiated poly-crystalline CVD diamond over a range of particle fluxes from 2 kHz/cm2 to 10 MHz/cm2. The pulse height of the sensors was measured with readout electronics with a peaking time of 6 ns. In addition functionality of poly-crystalline CVD diamond 3D devices was demonstrated in beam tests and 3D diamond detectors are shown to be a promising technology for applications in future high luminosity experiments.

High electric breakdown strength and energy density in vinylidene fluoride oligomer/poly(vinylidene fluoride) blend thin films

NASA Astrophysics Data System (ADS)

Rahimabady, Mojtaba; Chen, Shuting; Yao, Kui; Eng Hock Tay, Francis; Lu, Li

2011-10-01

Dense α-phase blend films of vinylidene fluoride (VDF) oligomer and poly(vinylidene fluoride) (PVDF) of various compositions were prepared from chemical solution deposition. The dielectric constant of the films was unexpectedly lower, and the mechanical strength was higher than either of the two components, leading to high electromechanical dielectric breakdown strength (>850 MV/m vs. 300˜500 MV/m for typical PVDF-based films). The properties were attributed to the unique blend structure with high crystallinity and densely packed rigid amorphous phase incorporating long and short chains. A maximum polarization of 162 mC/m2 and a large electric energy density up to 27.3 J/cm3 were obtained.

Note: Influence of rinsing and drying routines on growth of multilayer thin films using automated deposition system.

PubMed

Gamboa, Daniel; Priolo, Morgan A; Ham, Aaron; Grunlan, Jaime C

2010-03-01

A versatile, high speed robot for layer-by-layer deposition of multifunctional thin films, which integrates concepts from previous dipping systems, has been designed with dramatic improvements in software, positioning, rinsing, drying, and waste removal. This system exploits the electrostatic interaction of oppositely charged species to deposit nanolayers (1-10 nm thick) from water onto the surface of a substrate. Dip times and number of deposited layers are adjustable through a graphical user interface. In between dips the system spray rinses and dries the substrate by positioning it in the two-tiered rinse-dry station. This feature significantly reduces processing time and provides the flexibility to choose from four different procedures for rinsing and drying. Assemblies of natural montmorillonite clay and polyethylenimine are deposited onto 175 microm poly(ethylene terephthalate) film to demonstrate the utility of this automated deposition system. By altering the type of rinse-dry procedure, these clay-based assemblies are shown to exhibit variations in film thickness and oxygen transmission rate. This type of system reproducibly deposits films containing 20 or more layers and may also be useful for other types of coatings that make use of dipping.

Protection of Polymers from the Space Environment by Atomic Layer Deposition

NASA Astrophysics Data System (ADS)

Lindholm, Ned F.; Zhang, Jianming; Minton, Timothy K.; O'Patchen, Jennifer; George, Steven M.; Groner, Markus D.

2009-01-01

Polymers in space may be subjected to a barrage of incident atoms, photons, and/or ions. For example, oxygen atoms can etch and oxidize these materials. Photons may act either alone or in combination with oxygen atoms to degrade polymers and paints and thus limit their usefulness. Colors fade under the intense vacuum ultraviolet (VUV) solar radiation. Ions can lead to the build-up of static charge on polymers. Atomic layer deposition (ALD) techniques can provide coatings that could mitigate many challenges for polymers in space. ALD is a gas-phase technique based on two sequential, self-limiting surface reactions, and it can deposit very uniform, conformal, and pinhole-free films with atomic layer control. We have studied the efficacy of various ALD coatings to protect Kapton® polyimide, FEP Teflon®, and poly(methyl methacrylate) films from atomic-oxygen and VUV attack. Atomic-oxygen and VUV studies were conducted with the use of a laser-breakdown source for hyperthermal O atoms and a D2 lamp as a source of VUV light. These studies used a quartz crystal microbalance (QCM) to monitor mass loss in situ, as well as surface profilometry and scanning electron microscopy to study the surface recession and morphology changes ex situ. Al2O3 ALD coatings applied to polyimide and FEP Teflon® films protected the underlying substrates from O-atom attack, and ZnO coatings protected the poly(methyl methacrylate) substrate from VUV-induced damage.

Application of poly (p-phenylene oxide) as blocking layer to reduce self-discharge in supercapacitors

NASA Astrophysics Data System (ADS)

Tevi, Tete; Yaghoubi, Houman; Wang, Jing; Takshi, Arash

2013-11-01

Supercapacitors are electrochemical energy storage devices with high power density. However, application of supercapacitors is limited mainly due to their high leakage current. In this work, application of an ultra-thin layer of electrodeposited poly (p-phenylene oxide) (PPO) has been investigated as a blocking layer to reduce the leakage current. The polymer was first deposited on a glassy carbon electrode. The morphology of the film was studied by atomic force microscopy (AFM), and the film thickness was estimated to be ˜1.5 nm by using the electrochemical impedance spectroscopy (EIS) technique. The same deposition method was applied to coat the surface of the activated carbon electrodes of a supercapacitor with PPO. The specific capacitance, the leakage current, and the series resistance were measured in two devices with and without the blocking layer. The results demonstrate that the application of the PPO layer reduced the leakage current by ˜78%. However, the specific capacitance was decreased by ˜56%, when the blocking layer was applied. Due to the lower rate of self-discharge, the suggested approach can be applied to fabricate devices with longer charge storage time.

Inorganic-organic hybrid coatings on stainless steel by layer-by-layer deposition and surface-initiated atom-transfer-radical polymerization for combating biocorrosion.

PubMed

Yuan, S J; Pehkonen, S O; Ting, Y P; Neoh, K G; Kang, E T

2009-03-01

To improve the biocorrosion resistance of stainless steel (SS) and to confer the bactericidal function on its surface for inhibiting bacterial adhesion and biofilm formation, well-defined inorganic-organic hybrid coatings, consisting of the inner compact titanium oxide multilayers and outer dense poly(vinyl-N-hexylpyridinium) brushes, were successfully developed. Nanostructured titanium oxide multilayer coatings were first built up on the SS substrates via the layer-by-layer sol-gel deposition process. The trichlorosilane coupling agent, containing the alkyl halide atom-transfer-radical polymerization (ATRP) initiator, was subsequently immobilized on the titanium oxide coatings for surface-initiated ATRP of 4-vinylpyridine (4VP). The pyridium nitrogen moieties of the covalently immobilized 4VP polymer, or P(4VP), brushes were quaternized with hexyl bromide to produce a high concentration of quaternary ammonium salt on the SS surfaces. The excellent antibacterial efficiency of the grafted polycations, poly(vinyl-N-pyridinium bromide), was revealed by viable cell counts and atomic force microscopy images of the surface. The effectiveness of the hybrid coatings in corrosion protection was verified by the Tafel plot and electrochemical impedance spectroscopy measurements.

Hydrogel-laden paper scaffold system for origami-based tissue engineering

PubMed Central

Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S.

2015-01-01

In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca2+. This procedure ensures the formation of alginate hydrogel on the paper due to Ca2+ diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs. PMID:26621717

Gas Permeability and Permselectivity of Poly(L-Lactic Acid)/SiOx Film and Its Application in Equilibrium-Modified Atmosphere Packaging for Chilled Meat.

PubMed

Dong, Tungalag; Song, Shuxin; Liang, Min; Wang, Yu; Qi, Xiaojing; Zhang, Yuqin; Yun, Xueyan; Jin, Ye

2017-01-01

A layer of SiO x was deposited on the surface of poly(L-lactic acid) (PLLA) film to fabricate a PLLA/SiO x layered film, by plasma-enhanced chemical vapor deposition (PECVD) process. PLLA/SiO x film showed Young's modulus and tensile strength increased by 119.2% and 91.6%, respectively, over those of neat PLLA film. At 5 °C, the oxygen (O 2 ) and carbon dioxide (CO 2 ) permeability of PLLA/SiO x film decreased by 78.7% and 71.7%, respectively, and the CO 2 /O 2 permselectivity increased by 32.5%, compared to that of the neat PLLA film. When the PLLA/SiO x film was applied to the equilibrium-modified atmosphere packaging of chilled meat, the gas composition in packaging reached a dynamic equilibrium with 6% to 11% CO 2 and 8% to 13% O 2 . Combined with tea polyphenol pads, which effectively inhibited the microbial growth, the desirable color of meat was maintained and an extended shelf life of 52 d was achieved for the chilled meat. © 2016 Institute of Food Technologists®.

Hydrogel-laden paper scaffold system for origami-based tissue engineering.

PubMed

Kim, Su-Hwan; Lee, Hak Rae; Yu, Seung Jung; Han, Min-Eui; Lee, Doh Young; Kim, Soo Yeon; Ahn, Hee-Jin; Han, Mi-Jung; Lee, Tae-Ik; Kim, Taek-Soo; Kwon, Seong Keun; Im, Sung Gap; Hwang, Nathaniel S

2015-12-15

In this study, we present a method for assembling biofunctionalized paper into a multiform structured scaffold system for reliable tissue regeneration using an origami-based approach. The surface of a paper was conformally modified with a poly(styrene-co-maleic anhydride) layer via initiated chemical vapor deposition followed by the immobilization of poly-l-lysine (PLL) and deposition of Ca(2+). This procedure ensures the formation of alginate hydrogel on the paper due to Ca(2+) diffusion. Furthermore, strong adhesion of the alginate hydrogel on the paper onto the paper substrate was achieved due to an electrostatic interaction between the alginate and PLL. The developed scaffold system was versatile and allowed area-selective cell seeding. Also, the hydrogel-laden paper could be folded freely into 3D tissue-like structures using a simple origami-based method. The cylindrically constructed paper scaffold system with chondrocytes was applied into a three-ring defect trachea in rabbits. The transplanted engineered tissues replaced the native trachea without stenosis after 4 wks. As for the custom-built scaffold system, the hydrogel-laden paper system will provide a robust and facile method for the formation of tissues mimicking native tissue constructs.

Collagen density gradient on three-dimensional printed poly(ε-caprolactone) scaffolds for interface tissue engineering.

PubMed

D'Amora, Ugo; D'Este, Matteo; Eglin, David; Safari, Fatemeh; Sprecher, Christoph M; Gloria, Antonio; De Santis, Roberto; Alini, Mauro; Ambrosio, Luigi

2018-02-01

The ability to engineer scaffolds that resemble the transition between tissues would be beneficial to improve repair of complex organs, but has yet to be achieved. In order to mimic tissue organization, such constructs should present continuous gradients of geometry, stiffness and biochemical composition. Although the introduction of rapid prototyping or additive manufacturing techniques allows deposition of heterogeneous layers and shape control, the creation of surface chemical gradients has not been explored on three-dimensional (3D) scaffolds obtained through fused deposition modelling technique. Thus, the goal of this study was to introduce a gradient functionalization method in which a poly(ε-caprolactone) surface was first aminolysed and subsequently covered with collagen via carbodiimide reaction. The 2D constructs were characterized for their amine and collagen contents, wettability, surface topography and biofunctionality. Finally, chemical gradients were created in 3D printed scaffolds with controlled geometry and porosity. The combination of additive manufacturing and surface modification is a viable tool for the fabrication of 3D constructs with controlled structural and chemical gradients. These constructs can be employed for mimicking continuous tissue gradients for interface tissue engineering. Copyright © 2017 John Wiley & Sons, Ltd.

Stability of self-assembled polymer films investigated by optical laser reflectometry.

PubMed

Dejeu, Jérôme; Diziain, Séverine; Dange, Catherine; Membrey, François; Charraut, Daniel; Foissy, Alain

2008-04-01

We studied the influence of post-treatment rinsing after the formation of self-assembled polyelectrolyte films made with the weak base poly(allylamine hydrochloride) (PAH) and the strong acid poly(styrene sulfonate) (PSS). The stability of the film was studied using optical fixed-angle laser reflectometry to measure the release of polymeric material and AFM experiments to reveal the change of morphology and thickness. We found that the polymer films were stable upon rinsing when the pH was the same in the solution as that used in the buildup (pH 9). The films released most of the polymeric material when rinsed at higher pH values, but a layer remained that corresponded to a PAH monolayer directly bound with the silica surface. Films containing at least four bilayers were stable upon rinsing at lower pH values, but the stability of thinner films depended on the type of the last polymer deposited. They were stable in the case of PSS as an outermost deposit, but they released a large part of their material in the case of PAH. The stability results were determined using a simple model of the step-by-step assembly of the polymer film described formerly.

Continuous, highly flexible, and transparent graphene films by chemical vapor deposition for organic photovoltaics.

PubMed

Gomez De Arco, Lewis; Zhang, Yi; Schlenker, Cody W; Ryu, Koungmin; Thompson, Mark E; Zhou, Chongwu

2010-05-25

We report the implementation of continuous, highly flexible, and transparent graphene films obtained by chemical vapor deposition (CVD) as transparent conductive electrodes (TCE) in organic photovoltaic cells. Graphene films were synthesized by CVD, transferred to transparent substrates, and evaluated in organic solar cell heterojunctions (TCE/poly-3,4-ethylenedioxythiophene:poly styrenesulfonate (PEDOT:PSS)/copper phthalocyanine/fullerene/bathocuproine/aluminum). Key to our success is the continuous nature of the CVD graphene films, which led to minimal surface roughness ( approximately 0.9 nm) and offered sheet resistance down to 230 Omega/sq (at 72% transparency), much lower than stacked graphene flakes at similar transparency. In addition, solar cells with CVD graphene and indium tin oxide (ITO) electrodes were fabricated side-by-side on flexible polyethylene terephthalate (PET) substrates and were confirmed to offer comparable performance, with power conversion efficiencies (eta) of 1.18 and 1.27%, respectively. Furthermore, CVD graphene solar cells demonstrated outstanding capability to operate under bending conditions up to 138 degrees , whereas the ITO-based devices displayed cracks and irreversible failure under bending of 60 degrees . Our work indicates the great potential of CVD graphene films for flexible photovoltaic applications.

Solution-processed highly conductive PEDOT:PSS/AgNW/GO transparent film for efficient organic-Si hybrid solar cells.

PubMed

Xu, Qiaojing; Song, Tao; Cui, Wei; Liu, Yuqiang; Xu, Weidong; Lee, Shuit-Tong; Sun, Baoquan

2015-02-11

Hybrid solar cells based on n-Si/poly(3,4-ethylenedioxythiophene):poly(styrene- sulfonate) (PEDOT:PSS) heterojunction promise to be a low cost photovoltaic technology by using simple device structure and easy fabrication process. However, due to the low conductivity of PEDOT:PSS, a metal grid deposited by vacuum evaporation method is still required to enhance the charge collection efficiency, which complicates the device fabrication process. Here, a solution-processed graphene oxide (GO)-welded silver nanowires (AgNWs) transparent conductive electrode (TCE) was employed to replace the vacuum deposited metal grid. A unique "sandwich" structure was developed by embedding an AgNW network between PEDOT:PSS and GO with a figure-of-merit of 8.6×10(-3) Ω(-1), which was even higher than that of sputtered indium tin oxide electrode (6.6×10(-3) Ω(-1)). A champion power conversion efficiency of 13.3% was achieved, because of the decreased series resistance of the TCEs as well as the enhanced built-in potential (Vbi) in the hybrid solar cells. The TCEs were obtained by facile low-temperature solution process method, which was compatible with cost-effective mass production technology.

Electrochemical quantification of some water soluble vitamins in commercial multi-vitamin using poly-amino acid caped by graphene quantum dots nanocomposite as dual signal amplification elements.

PubMed

Shadjou, Nasrin; Hasanzadeh, Mohammad; Omari, Ali

2017-12-15

Rapid analyses of some water soluble vitamins (Vitamin B2, B9, and C) in commercial multi vitamins could be routinely performed in analytical laboratories. This study reports on the electropolymerization of a low toxic and biocompatible polymer "poly aspartic acid-graphene quantum dots" as a novel strategy for surface modification of glassy carbon electrode and preparation a new interface for measurement of selected vitamins in commercial multi vitamins. Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of graphene quantum dots nanostructures on a poly aspartic acid using cyclic voltammetry techniques in the regime of -1.5 to 2 V. The field emission scanning electron microscopy indicated immobilization of graphene quantum dots onto poly aspartic acid film. The modified electrode possessed as an effective electroactivity for detection of water soluble vitamins by using cyclic voltammetry, chronoamperometry and differential pulse voltammetry. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between the excellent properties of poly aspartic acid as semiconducting polymer, graphene quantum dots as high density of edge plane sites and chemical modification. Under the optimized analysis conditions, the prepared sensor for detection of VB2, VB9, and VC showed a low limit of quantification 0.22, 0.1, 0.1 μM, respectively. Copyright © 2017. Published by Elsevier Inc.

Growth mechanism and elemental distribution of beta-Ga2O3 crystalline nanowires synthesized by cobalt-assisted chemical vapor deposition.

PubMed

Wang, Hui; Lan, Yucheng; Zhang, Jiaming; Crimp, Martin A; Ren, Zhifeng

2012-04-01

Long beta-Ga2O3 crystalline nanowires are synthesized on patterned silicon substrates using chemical vapor deposition technique. Advanced electron microscopy indicates that the as-grown beta-Ga2O3 nanowires are consisted of poly-crystalline (Co, Ga)O tips and straight crystalline beta-Ga2O3 stems. The catalytic cobalt not only locates at the nanowire tips but diffuses into beta-Ga2O3 nanowire stems several ten nanometers. A solid diffusion growth mechanism is proposed based on the spatial elemental distribution along the beta-Ga2O3 nanowires at nanoscale.

Substrate-Independent Epitaxial Growth of the Metal-Organic Framework MOF-508a.

PubMed

Wilson, M; Barrientos-Palomo, S N; Stevens, P C; Mitchell, N L; Oswald, G; Nagaraja, C M; Badyal, J P S

2018-01-31

Plasmachemical deposition is a substrate-independent method for the conformal surface functionalization of solid substrates. Structurally well-defined pulsed plasma deposited poly(1-allylimidazole) layers provide surface imidazole linker groups for the directed liquid-phase epitaxial (layer-by-layer) growth of metal-organic frameworks (MOFs) at room temperature. For the case of microporous [Zn (benzene-1,4-dicarboxylate)-(4,4'-bipyridine) 0.5 ] (MOF-508), the MOF-508a polymorph containing two interpenetrating crystal lattice frameworks undergoes orientated Volmer-Weber growth and displays CO 2 gas capture behavior at atmospheric concentrations in proportion to the number of epitaxially grown MOF-508 layers.

Transgene Delivery using Poly(amino ether)-Gold Nanorod Assemblies

PubMed Central

Ramos, James; Rege, Kaushal

2012-01-01

Gold nanorods (GNRs) have emerged as promising nanomaterials for biosensing, imaging, photothermal treatment and therapeutic delivery for several diseases, including cancer. We have generated poly(amino ether)-functionalized gold nanorods (PAE-GNRs) using a layer-by-layer deposition approach; polymers from a poly(amino ether) library recently synthesized in our laboratory were employed to generate the PAE-GNR assemblies. PAE-GNR assemblies demonstrate long-term colloidal stability as well as the capacity to bind plasmid DNA by means of electrostatic interactions. Sub-toxic concentrations of PAE-GNRs were employed to deliver plasmid DNA to prostate cancer cells in vitro. PAE-GNRs generated using 1,4C-1,4Bis, a cationic polymer from our laboratory demonstrated significantly higher transgene expression and exhibited lower cytotoxicities when compared to similar assemblies generated using 25 kDa poly(ethylene imine) (PEI25k-GNRs), a current standard for polymer-mediated gene delivery. The roles of polyelectrolyte chemistry and zeta-potential in determining transgene expression efficacies of PAE-GNR assemblies were investigated. Our results indicate that stable and effective PAE-GNR assemblies are a promising engineered platform for transgene delivery. PAE-GNRs also have the potential to be used simultaneously for photothermal ablation, photothermally enhanced drug and gene delivery, and biological imaging, thus making them a powerful theranostic platform. PMID:22170455

Evaluation of PEG and mPEG-co-(PGA-co-PDL) microparticles loaded with sodium diclofenac

PubMed Central

Tawfeek, Hesham M.

2013-01-01

The aim of this study was to synthesize and evaluate novel biodegradable polyesters namely; poly(ethylene glycol)-Poly(glycerol adipate-co-ω-pentadecalactone), PEG-PGA-co-PDL-PEG, and poly(ethylene glycol methyl ether)-Poly(glycerol adipate-co-ω-pentadecalactone), PGA-co-PDL-PEGme as an alternative sustained release carrier for lung delivery compared with non-PEG containing polymer PGA-co-PDL. The co-polymers were synthesized through lipase catalysis ring opening polymerization reaction and characterized using GPC, FT-IR, 1H-NMR and surface contact angle. Furthermore, microparticles containing a model hydrophilic drug, sodium diclofenac, were prepared via spray drying from a modified single emulsion and characterized for their encapsulation efficiency, geometrical particle size, zeta potential, tapped density, primary aerodynamic diameter, amorphous nature, morphology, in vitro release and the aerosolization performance. Microparticles fabricated from mPEG-co-polymer can be targeted to the lung periphery with an optimum in vitro deposition. Furthermore, a significantly higher in vitro release (p > 0.05, ANOVA/Dunnett’s) was observed with the PEG and mPEG-co-polymers compared to PGA-co-PDL. In addition, these co-polymers have a good safety profile upon testing on human bronchial epithelial, 16HBE14o- cell lines. PMID:24227959

A screen-printed carbon electrode modified with gold nanoparticles, poly(3,4-ethylenedioxythiophene), poly(styrene sulfonate) and a molecular imprint for voltammetric determination of nitrofurantoin.

PubMed

Dechtrirat, Decha; Yingyuad, Peerada; Prajongtat, Pongthep; Chuenchom, Laemthong; Sriprachuabwong, Chakrit; Tuantranont, Adisorn; Tang, I-Ming

2018-04-23

A molecularly imprinted polymer (MIP) and a nanocomposite prepared from gold nanoparticles (AuNP) and poly(3,4-ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT:PSS) were deposited on a screen-printed carbon electrode (SPCE). The nanocomposite was prepared by one-pot simultaneous in-situ formation of AuNPs and PEDOT:PSS and was then inkjet-coated onto the SPCE. The MIP film was subsequently placed on the modified SPCE by co-electrodeposition of o-phenylenediamine and resorcinol in the presence of the antibiotic nitrofurantoin (NFT). Using differential pulse voltammetry (DPV), response at the potential of ~ 0.1 V (vs. Ag/AgCl) is linear in 1 nM to 1000 nM NFT concentration range, with a remarkably low detection limit (at S/N = 3) of 0.1 nM. This is two orders of magnitude lower than that of the control MIP sensor without the nanocomposite interlayer, thus showing the beneficial effect of AuNP-PEDOT:PSS. The electrode is highly reproducible (relative standard deviation 3.1% for n = 6) and selective over structurally related molecules. It can be re-used for at least ten times and was found to be stable for at least 45 days. It was successfully applied to the determination of NFT in (spiked) feed matrices and gave good recoveries. Graphical abstract Schematic representation of a voltammetric sensor for the determination of nitrofurantoin. The sensor is based on a screen-printed carbon electrode (SPCE) modified with an inkjet-printed gold nanoparticles-poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) nanocomposite and a molecularly imprinted polymer.

Folding and self-assembly of polypeptides: Dynamics and thermodynamics from molecular simulation

NASA Astrophysics Data System (ADS)

Fluitt, Aaron Michael

Empowered by their exquisite three-dimensional structures, or "folds," proteins carry out biological tasks with high specificity, efficiency, and fidelity. The fold that optimizes biological function represents a stable configuration of the constituent polypeptide molecule(s) under physiological conditions. Proteins and polypeptides are not static, however: battered by thermal motion, they explore a distribution of folds that is determined by the sequence of amino acids, the presence and identity of other molecules, and the thermodynamic conditions. In this dissertation, we apply molecular simulation techniques to the study of two polypeptides that have unusually diffuse distributions of folds under physiological conditions: polyglutamine (polyQ) and islet amyloid polypeptide (IAPP). Neither polyQ nor IAPP adopts a predominant fold in dilute aqueous solution, but at sufficient concentrations, both are prone to self-assemble into stable, periodic, and highly regular aggregate structures known as amyloid. The appearance of amyloid deposits of polyQ in the brain, and of IAPP in the pancreas, are associated with Huntington's disease and type 2 diabetes, respectively. A molecular view of the mechanism(s) by which polyQ and IAPP fold and self-assemble will enhance our understanding of disease pathogenesis, and it has the potential to accelerate the development of therapeutics that target early-stage aggregates. Using molecular simulations with spatial and temporal resolution on the atomic scale, we present analyses of the structural distributions of polyQ and IAPP under various conditions, both in and out of equilibrium. In particular, we examine amyloid fibers of polyQ, the IAPP dimer in solution, and single IAPP fragments at a lipid bilayer. We also benchmark the molecular models, or "force fields," available for such studies, and we introduce a novel simulation algorithm.

A Critical Review: Management and Surgical Options for Articular Defects in the Hip.

PubMed

Makhni, Eric C; Stone, Austin V; Ukwuani, Gift C; Zuke, William; Garabekyan, Tigran; Mei-Dan, Omer; Nho, Shane J

2017-07-01

Patients with articular cartilage lesions of the hip may present with pain and symptoms that may be vague in nature and onset. Therefore, a thorough history and physical examination should be performed for every patient presenting with hip pain and/or disability. The management may be operative or nonoperative. Nonoperative management includes a trial of rest and/or activity modification, along with anti-inflammatory medications, physical therapy, and biologic injections. Operative treatment in the form of arthroscopic techniques continues to decrease morbidity and offer innovative solutions and new applications for microfracture, ACT, and AMIC. Copyright © 2017 Elsevier Inc. All rights reserved.

A sole multi-analyte receptor responds with three distinct fluorescence signals: traffic signal like sensing of Al(3+), Zn(2+) and F(-).

PubMed

Datta, Barun Kumar; Thiyagarajan, Durairaj; Ramesh, Aiyagari; Das, Gopal

2015-08-07

A dialdehyde-based multi-analyte sensor renders distinctive emission spectra for Al(3+), Zn(2+) and F(-) ions. The ligand exhibited different types of interactions with these three different ions resulting in the enhancement of fluorescence intensity at three different wavelengths. All the sensing processes were studied in detail by absorption spectroscopy, emission spectroscopy and (1)H-NMR titration experiment. The ligand has the working ability in a wide pH range including the physiological pH. The ligand is non-toxic and amicable for sensing intracellular Al(3+) and Zn(2+) in live HeLa cells.

Elder mediation in theory and practice: study results from a national caregiver mediation demonstration project.

PubMed

Crampton, Alexandra

2013-01-01

Mediation is a process through which a third party facilitates discussion among disputing parties to help them identify interests and ideally reach an amicable solution. Elder mediation is a growing subspecialty to address conflicts involving older adults, primarily involving caregiving or finances. Mediation is theorized to empower participants but critics argue that it can exacerbate power imbalances among parties and coerce consensus. These contested claims are examined through study of a national caregiver mediation demonstration project. Study implications underscore the importance of gerontological social work expertise to ensure the empowerment of vulnerable older adults in mediation sessions.

Elder Mediation in Theory and Practice: Study Results From a National Caregiver Mediation Demonstration Project

PubMed Central

Crampton, Alexandra

2014-01-01

Mediation is a process through which a third party facilitates discussion among disputing parties to help them identify interests and ideally reach an amicable solution. Elder mediation is a growing subspecialty to address conflicts involving older adults, primarily involving caregiving or finances. Mediation is theorized to empower participants but critics argue that it can exacerbate power imbalances among parties and coerce consensus. These contested claims are examined through study of a national caregiver mediation demonstration project. Study implications underscore the importance of gerontological social work expertise to ensure the empowerment of vulnerable older adults in mediation sessions. PMID:23767767

Electrochemical Sensor Coating Based on Electrophoretic Deposition of Au-Doped Self-Assembled Nanoparticles.

PubMed

Zhang, Rongli; Zhu, Ye; Huang, Jing; Xu, Sheng; Luo, Jing; Liu, Xiaoya

2018-02-14

The electrophoretic deposition (EPD) of self-assembled nanoparticles (NPs) on the surface of an electrode is a new strategy for preparing sensor coating. By simply changing the deposition conditions, the electrochemical response for an analyte of deposited NPs-based coating can be controlled. This advantage can decrease the difference between different batches of sensor coating and ensure the reproducibility of each sensor. This work investigated the effects of deposition conditions (including deposition voltage, pH value of suspension, and deposition time) on the structure and the electrochemical response for l-tryptophan of sensor coating formed from Au-doped poly(sodium γ-glutamate) with pendant dopamine units nanohybrids (Au/γ-PGA-DA NBs) via the EPD method. The structure and thickness of the deposited sensor coating were measured by atomic force microscopy, which demonstrated that the structure and thickness of coating can be affected by the deposition voltage, the pH value of the suspension, and the deposition time. The responsive current for l-tryptophan of the deposited sensor coating were measured by differential pulse voltammetry, which showed that the responsive current value was affected by the structure and thickness of the deposited coating. These arguments suggested that a rich design-space for tuning the electrochemical response for analyte and a source of variability in the structure of sensor coating can be provided by the deposition conditions. When Au/γ-PGA-DA NBs were deposited on the electrode surface and formed a continuous coating with particle morphology and thinner thickness, the deposited sensor coating exhibited optimal electrochemical response for l-tryptophan.

Osteoinduction and proliferation of bone-marrow stromal cells in three-dimensional poly (ε-caprolactone)/ hydroxyapatite/collagen scaffolds.

PubMed

Wang, Ting; Yang, Xiaoyan; Qi, Xin; Jiang, Chaoyin

2015-05-08

Osteoinduction and proliferation of bone-marrow stromal cells (BMSCs) in three-dimensional (3D) poly(ε-caprolactone) (PCL) scaffolds have not been studied throughly and are technically challenging. This study aimed to optimize nanocomposites of 3D PCL scaffolds to provide superior adhesion, proliferation and differentiation environment for BMSCs in this scenario. BMSCs were isolated and cultured in a novel 3D tissue culture poly(ε-caprolactone) (PCL) scaffold coated with poly-lysine, hydroxyapatite (HAp), collagen and HAp/collagen. Cell morphology was observed and BMSC biomarkers for osteogenesis, osteoblast differentiation and activation were analyzed. Scanning Electron Microscope (SEM) micrographs showed that coating materials were uniformly deposited on the surface of PCL scaffolds and BMSCs grew and aggregated to form clusters during 3D culture. Both mRNA and protein levels of the key players of osteogenesis and osteoblast differentiation and activation, including runt-related transcription factor 2 (Runx2), alkaline phosphates (ALP), osterix, osteocalcin, and RANKL, were significantly higher in BMSCs seeded in PCL scaffolds coated with HAp or HAp/collagen than those seeded in uncoated PCL scaffolds, whereas the expression levels were not significantly different in collagen or poly-lysine coated PCL scaffolds. In addition, poly-lysine, collagen, HAp/collagen, and HAp coated PCL scaffolds had significantly more viable cells than uncoated PCL scaffolds, especially scaffolds with HAp/collagen and collagen-alone coatings. That BMSCs in HAp or HAp/collagen PCL scaffolds had remarkably higher ALP activities than those in collagen-coated alone or uncoated PCL scaffolds indicating higher osteogenic differentiation levels of BMSCs in HAp or HAp/collagen PCL scaffolds. Moreover, morphological changes of BMSCs after four-week of 3D culture confirmed that BMSCs successfully differentiated into osteoblast with spread-out phenotype in HAp/collagen coated PCL scaffolds. This study showed a proof of concept for preparing biomimetic 3D poly (ε-caprolactone)/ hydroxyapatite/collagen scaffolds with excellent osteoinduction and proliferation capacity for bone regeneration.

Investigation of transient dynamics of capillary assisted particle assembly yield

NASA Astrophysics Data System (ADS)

Virganavičius, D.; Juodėnas, M.; Tamulevičius, T.; Schift, H.; Tamulevičius, S.

2017-06-01

In this paper, the transient behavior of the particle assembly yield dynamics when switching from low yield to high yield deposition at different velocity and thermal regimes is investigated. Capillary force assisted particle assembly (CAPA) using colloidal suspension of green fluorescent 270 nm diameter polystyrene beads was performed on patterned poly (dimethyl siloxane) substrates using a custom-built deposition setup. Two types of patterns with different trapping site densities were used to assess CAPA process dynamics and the influence of pattern density and geometry on the deposition yield transitions. Closely packed 300 nm diameter circular pits ordered in hexagonal arrangement with 300 nm pitch, and 2 × 2 mm2 square pits with 2 μm spacing were used. 2-D regular structures of the deposited particles were investigated by means of optical fluorescence and scanning electron microscopy. The fluorescence micrographs were analyzed using a custom algorithm enabling to identify particles and calculate efficiency of the deposition performed at different regimes. Relationship between the spatial distribution of particles in transition zone and ambient conditions was evaluated and quantified by approximation of the yield profile with a logistic function.

Block Copolymer Patterns as Templates for the Electrocatalyzed Deposition of Nanostructures on Electrodes and for the Generation of Surfaces of Controlled Wettability.

PubMed

Chandaluri, Chanchayya Gupta; Pelossof, Gilad; Tel-Vered, Ran; Shenhar, Roy; Willner, Itamar

2016-01-20

ITO electrodes modified with a nanopatterned film of polystyrene-block-poly(2-vinylpyridine), PS-b-P2VP, where the P2VP domains are quaternized with iodomethane, are used for selective deposition of redox-active materials. Electrochemical studies (cyclic voltammetry, Faradaic impedance measurements) indicate that the PS domains insulate the conductive surface toward redox labels in solution. In turn, the quaternized P2VP domains electrostatically attract negatively charged redox labels solubilized in the electrolyte solution, resulting in an effective electron transfer between the electrode and the redox label. This phenomenon is implemented for the selective deposition of the electroactive Prussian blue on the nanopatterned surface and for the electrochemical deposition of Au nanoparticles, modified with a monolayer of p-aminothiophenol/2-mercaptoethanesulfonic acid, on the quaternized P2VP domains. The patterned Prussian blue-modified surface enables controlling the wettability properties by the content of the electrochemically deposited Prussian blue. Controlled wettability is unattainable with the homopolymer-modified surface, attesting to the role of the nanopattern.

Surface rejuvenation for multilayer metal deposition on polymer microspheres via self-seeded electroless plating

NASA Astrophysics Data System (ADS)

Karagoz, Bunyamin; Sirkecioglu, Okan; Bicak, Niyazi

2013-11-01

A surface rejuvenation process was developed for generation variable thickness of metal deposits on polymer microspheres via electroless plating. Thus, Ni(II), Cu(II) and Ag(I) complexes formed on triethylenetetramine (TETA) functional crosslinked poly(glycidyl methacrylate) (PGMA) microspheres were reduced to zero-valent metals. The resulting metals (1.1-1.5 mmol g-1) were employed as seed points for electroless metal plating (self-seeding) without using Pd or tin pre-activating species. Treatment of the metalized surfaces with hydrazine or hydrazinium formate was demonstrated to reactivate (rejuvenate) the surface and allows further metal deposition from electroless plating solutions. Followed repeating of the surface rejuvenation-metalization steps resulted in step wise increasing of the metal deposits (90-290 mg per g in each cycle), as inferred from metal analyses, ESEM and XPS analysis. Experiments showed that, after 6 times of cycling the metal deposits exceed 1 g per g of the microspheres on average. The process seemed to be promising for tuning up of the metal thickness by stepwise electroless plating.

Synthesis of Diamond-Like Carbon Films on Planar and Non-Planar Geometries by the Atmospheric Pressure Plasma Chemical Vapor Deposition Method

NASA Astrophysics Data System (ADS)

Noborisaka, Mayui; Hirako, Tomoaki; Shirakura, Akira; Watanabe, Toshiyuki; Morikawa, Masashi; Seki, Masaki; Suzuki, Tetsuya

2012-09-01

Diamond-like carbon (DLC) films were synthesized by the dielectric barrier discharge-based plasma deposition at atmospheric pressure and their hardness and gas barrier properties were measured. A decrease in size of grains and heating substrate temperature improved nano-hardness up to 3.3 GPa. The gas barrier properties of DLC-coated poly(ethylene terephthalate) (PET) sheets were obtained by 3-5 times of non-coated PET with approximately 0.5 µm in film thickness. The high-gas-barrier DLC films deposited on PET sheets are expected to wrap elevated bridge of the super express and prevent them from neutralization of concrete. We also deposited DLC films inside PET bottles by the microwave surface-wave plasma chemical vapor deposition (CVD) method at near-atmospheric pressure. Under atmospheric pressure, the films were coated uniformly inside the PET bottles, but did not show high gas barrier properties. In this paper, we summarize recent progress of DLC films synthesized at atmospheric pressure with the aimed of food packaging and concrete pillar.

Applications of Charge Transfer Devices in Spectroscopy.

DTIC Science & Technology

1988-02-04

Langmuir - Blodgett films deposited on glass and silicon substrates. A direct comparison by Pemberton and Sobocinski (18) of the Raman spectra obtained...wavelength. The measurements are then repeated with an uncoated sheet of poly - ester serving as the reference blank. The double monochromator...give the best sensitivity at trace concentration levels. The less intense lines resulting from non-reson- -’ ance and ionic transitions are used for

Secondary ion mass spectrometric investigation on ruthenium oxide systems: a comparison between poly- and nanocrystalline deposits

PubMed

Barison; Barreca; Daolio; Fabrizio; Piccirillo

2000-01-01

The influence of different RuO(2) crystallite sizes was investigated by secondary ion mass spectrometry (SIMS) on the oxide deposited on various support materials (Ni, Ti, Al(2)O(3), oxidized Si(100)). In order to examine the effect of an oxidic environment on the film structure, RuO(2) 20%-TiO(2) 80% at. mixed oxide was deposited on Ti. The polycrystalline coatings were prepared by heating the Ru (and Ti)-containing solution dropped on the supports.1 RuO(2) nanocrystalline coatings were grown by chemical vapor deposition (CVD) from Ru(COD)(eta(3)-allyl)(2).2 The identification of mixed oxide clusters showed the higher reactivity of Ni and Al(2)O(3) over the other substrates. Diffusion and migration characteristics were observed to be influenced by the nature of the support. The results are complementary to those of a previous SIMS investigation.3 Copyright 2000 John Wiley & Sons, Ltd.

Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

DOE PAGES

Dong, Ban Xuan; Li, Anton; Strzalka, Joseph; ...

2016-09-18

The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations andmore » the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.« less

Molecular organization in MAPLE-deposited conjugated polymer thin films and the implications for carrier transport characteristics

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

Dong, Ban Xuan; Li, Anton; Strzalka, Joseph

The morphological structure of poly(3-hexylthiophene) (P3HT) thin films deposited by both Matrix Assisted Pulsed Laser Evaporation (MAPLE) and solution spin-casting methods are investigated. We found that the MAPLE samples possessed a higher degree of disorder, with random orientations of polymer crystallites along the side-chain stacking, π-π stacking, and conjugated backbone directions. Furthermore, the average molecular orientations and relative degrees of crystallinity of MAPLE-deposited polymer films are insensitive to the chemistries of the substrates onto which they were deposited; this is in stark contrast to the films prepared by the conventional spin-casting technique. In spite of the seemingly unfavorable molecular orientations andmore » the highly disordered morphologies, the in-plane charge carrier transport characteristics of the MAPLE samples are comparable to those of spin-cast samples, exhibiting similar transport activation energies (56 meV versus 54 meV) to those reported in the literature for high mobility polymers.« less

Deposition of amorphous carbon nitride films on flexible substrates by reactive sputtering for applications in light-driven active devices

NASA Astrophysics Data System (ADS)

Aono, Masami; Harata, Tomo; Odawara, Taku; Asai, Shinnosuke; Orihara, Dai; Nogi, Masaya

2018-01-01

Amorphous carbon nitride (a-CN x ) thin films deposited by reactive sputtering have great potential for driving source applications of light-driven active devices. We demonstrate, for the first time, the photoinduced deformation of a-CN x deposited on flexible substrates, namely, poly(ethylene naphthalate) (PEN) films and transparent cellulose nanopaper. a-CN x films without delamination were obtained on both substrates. By decreasing the thickness of PEN films, the photoinduced deformation became extremely large. A light-driven pump was fabricated using a-CN x -coated PEN films, and then the pumping motion was observed up to 10 Hz. When a He-Ne laser traced the surface of a-CN x films deposited on the nanopaper, the sample moved to the opposite side of the laser spot. The motion involved repeated expansions and contractions similar to the motion of caterpillars occurring owing to the temporary photoinduced deformation of a-CN x films.

Organic heterostructures deposited by MAPLE on AZO substrate

NASA Astrophysics Data System (ADS)

Socol, M.; Preda, N.; Stanculescu, A.; Breazu, C.; Florica, C.; Stanculescu, F.; Iftimie, S.; Girtan, M.; Popescu-Pelin, G.; Socol, G.

2017-09-01

Organic heterostructures based on poly(3-hexylthiophene) (P3HT) and fullerene (C60) as blends or multilayer were deposited on Al:ZnO (AZO) by Matrix-Assisted Pulsed Laser Evaporation (MAPLE) technique. The AZO layers were obtained by Pulsed Laser Deposition (PLD) on glass substrate, the high quality of the films being reflected by the calculated figure of merit. The organic heterostructures were investigated from morphological, optical and electrical point of view by atomic force microscopy (AFM), UV-vis spectroscopy, photoluminescence (PL) and current-voltage (I-V) measurements, respectively. The increase of the C60 content in the blend heterostructure has as result a high roughness. Compared with the multilayer heterostructure, those based on blends present an improvement in the electrical properties. Under illumination, the highest current value was recorded for the heterostructure based on the blend with the higher C60 amount. The obtained results showed that MAPLE is a useful technique for the deposition of the organic heterostructures on AZO as transparent conductor electrode.

Structural properties 3,16-bis triisopropylsilylethynyl (pentacene) (TIPS-pentacene) thin films onto organic dielectric layer using slide coating method

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

Rusnan, Fara Naila; Mohamad, Khairul Anuar; Seria, Dzul Fahmi Mohd Husin

3,16-bis triisopropylsilylethynyl (Pentacene) (TIPS-Pentacene) compactable interface property is important in order to have a good arrangement of molecular structure. Comparison for TIPS-Pentacene deposited between two different surface layers conducted. 0.1wt% TIPS-Pentacene diluted in chloroform were deposited onto poly(methylmeaclyrate) (PMMA) layered transparent substrates using slide coating method. X-ray diffraction (XRD) used to determine crystallinity of thin films. Series of (00l) diffraction peaks obtained with sharp first peaks (001) for TIPS-Pentacene deposited onto PMMA layer at 5.35° and separation of 16.3 Å. Morphology and surface roughness were carried out using scanning electron microscope (SEM) and surface profilemeter LS500, respectively.TIPS-Pentacene deposited onto PMMAmore » layer formed needled-like-shape grains with 10.26 nm surface roughness. These properties were related as thin film formed and its surface roughness plays important role towards good mobility devices.« less

Characteristics of Diamond-Like Carbon Films Deposited on Polymer Dental Materials

NASA Astrophysics Data System (ADS)

Ohtake, Naoto; Uchi, Tomio; Yasuhara, Toshiyuki; Takashima, Mai

2012-09-01

Characterizations of diamond-like carbon (DLC) deposited on a polymer artificial tooth were performed. DLC films were deposited on dental parts made of poly(methyl methacrylate) (PMMA) resin by dc-pulse plasma chemical vapor deposition (CVD) from methane. Wear resistance test results revealed that a DLC-coated resin tooth has a very high wear resistance against tooth brushing, and endures 24 h brushing without a marked weight decrease. Cell cultivation test results show that DLC plays an important role in preventing cell death. Moreover, a biocompatibility test using a rabbit revealed that a connective tissue in the vicinity of DLC-coated PMMA is significantly thinner than that of noncoated PMMA. The numbers of inflammatory cells in the vicinity of DLC-coated and noncoated surfaces are 0 and 508 cells/mm2, respectively. These results led us to conclude that DLC films are an excellent material for use as the coating of a polymer artificial tooth in terms of not only high wear resistance but also biocompatibility.

Improvement of Permeation of Solvent-Free Multilayer Encapsulation of Thin Films on Poly(ethylene terephthalate)

NASA Astrophysics Data System (ADS)

Han, Jin-Woo; Kang, Hee-Jin; Kim, Jong-Yeon; Kim, Gwi-Yeol; Seo, Dae-Shik

2006-12-01

In this study, inorganic multilayer thin-film encapsulation is adopted for the first time to protect an organic layer from moisture and oxygen. Inorganic multilayer thin-film encapsulation is deposited onto poly(ethylene terephthalate) (PET) using an electron beam and sputtering. The SiON/SiO2 and parylene layer show the most suitable properties. Under these conditions, the water vapor transmission rate (WVTR) for PET can be reduced from a level of 0.57 g m-2 day-1 (bare substrate) to 1× 10-5 g m-2 day-1 after the application of a SiON and SiO2 layer. These results indicate that PET/parylene/SiO2/SiON barrier coatings have high potential for flexible organic light-emitting diode (OLED) applications.

Synthesis, vapor growth, polymerization, and characterization of thin films of novel diacetylene derivatives of pyrrole. The use of computer modeling to predict chemical and optical properties of these diacetylenes and poly(diacetylenes)

NASA Technical Reports Server (NTRS)

Paley, M. S.; Frazier, D. O.; Abeledeyem, H.; Mcmanus, S. P.; Zutaut, S. E.

1992-01-01

In the present work two diacetylene derivatives of pyrrole which are predicted by semiempirical AM1 calculations to have very different properties, are synthesized; the polymerizability of these diacetylenes in the solid state is determined, and the results are compared to the computer predictions. Diacetylene 1 is novel in that the monomer is a liquid at room temperature; this may allow for the possibility of polymerization in the liquid state as well as the solid state. Thin poly(diacetylene) films are obtained from compound 1 by growing films of the monomer using vapor deposition and polymerizing with UV light; these films are then characterized. Interestingly, while the poly(diacetylene) from 1 does not possess good nonlinear optical properties, the monomer exhibits very good third-order effects (phase conjugation) in solution. Dilute acetone solutions of the monomer 1 give intensity-dependent refractive indices on the order of 10 exp -6 esu; these are 10 exp 6 times better than for CS2.

Study of P3HT/ PCBM morphology using Raman spectroscopy

NASA Astrophysics Data System (ADS)

Kumar, Sunil; Kumar, Manoj; Rathi, Sonika; Yadav, Anjali; Upadhyaya, Aditi; Gupta, Saral K.; Singh, Amarjeet

2018-05-01

In the present work we have deposited PEDOT: PSS (poly3,4-ethylene dioxythiophene -poly (styrenesulfonate)) then Pristine P3HT (Poly-3 hexylthiophene-2,5-diyl), PCBM (6,6- PhenylC61 butyric acid methyl ester) and its blend composite (P3HT:PCBM) thin films on ITO substrate via spin coating technique. Pristine P3HT, pristine PCBM and blend thin film samples were annealed at different temperatures (50°C, 80°C and 110°C) for 1 hr. Raman spectra was measured for each thin film samples as prepared (at room temperature or 25°C) and annealed at different temperatures (50°C, 80°C, 110°C). Then we calculated area under Raman peaks which is representation of Raman Intensity and observed that area under Raman peak varies with annealing temperatures. The increase in peak intensity appears due to increased crystallinity in annealed thin films. The mixing of PCBM hinders the crystallization of P3HT in blend. Mixed amorphous phase plays major role in charge transportation in electronic devices.

On the Discontinuity of Polycrystalline Silicon Thin Films Realized by Aluminum-Induced Crystallization of PECVD-Deposited Amorphous Si

NASA Astrophysics Data System (ADS)

Pan, Qingtao; Wang, Tao; Yan, Hui; Zhang, Ming; Mai, Yaohua

2017-04-01

Crystallization of glass/Aluminum (50, 100, 200 nm) /hydrogenated amorphous silicon (a-Si:H) (50, 100, 200 nm) samples by Aluminum-induced crystallization (AIC) is investigated in this article. After annealing and wet etching, we found that the continuity of the polycrystalline silicon (poly-Si) thin films was strongly dependent on the double layer thicknesses. Increasing the a-Si:H/Al layer thickness ratio would improve the film microcosmic continuity. However, too thick Si layer might cause convex or peeling off during annealing. Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX) are introduced to analyze the process of the peeling off. When the thickness ratio of a-Si:H/Al layer is around 1 to 1.5 and a-Si:H layer is less than 200 nm, the poly-Si film has a good continuity. Hall measurements are introduced to determine the electrical properties. Raman spectroscopy and X-ray diffraction (XRD) results show that the poly-Si film is completely crystallized and has a preferential (111) orientation.

All-solution-processed PbS quantum dot solar modules.

PubMed

Jang, Jihoon; Shim, Hyung Cheoul; Ju, Yeonkyeong; Song, Jung Hoon; An, Hyejin; Yu, Jong-Su; Kwak, Sun-Woo; Lee, Taik-Min; Kim, Inyoung; Jeong, Sohee

2015-05-21

A rapid increase in power conversion efficiencies in colloidal quantum dot (QD) solar cells has been achieved recently with lead sulphide (PbS) QDs by adapting a heterojunction architecture, which consists of small-area devices associated with a vacuum-deposited buffer layer with metal electrodes. The preparation of QD solar modules by low-cost solution processes is required to further increase the power-to-cost ratio. Herein we demonstrate all-solution-processed flexible PbS QD solar modules with a layer-by-layer architecture comprising polyethylene terephthalate (PET) substrate/indium tin oxide (ITO)/titanium oxide (TiO2)/PbS QD/poly(3-hexylthiophene) (P3HT)/poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS)/Ag, with an active area of up to 30 cm(2), exhibiting a power conversion efficiency (PCE) of 1.3% under AM 1.5 conditions (PCE of 2.2% for a 1 cm(2) unit cell). Our approach affords trade-offs between power and the active area of the photovoltaic devices, which results in a low-cost power source, and which is scalable to larger areas.

Graphene and poly(methyl methacrylate) composite laminates on flexible substrates for volatile organic compound detection

NASA Astrophysics Data System (ADS)

Rattanabut, Chanoknan; Wongwiriyapan, Winadda; Muangrat, Worawut; Bunjongpru, Win; Phonyiem, Mayuree; Song, Young Jae

2018-04-01

In this paper, we present a gas sensor for volatile organic compound (VOC) detection based on graphene and poly(methyl methacrylate) (GR/PMMA) composite laminates fabricated using CVD-grown graphene. Graphene was transferred to a poly(ethylene terephthalate) (PET) substrate by PMMA-supported wet transfer process without PMMA removal in order to achieve the deposition of GR/PMMA composite laminates on PET. The GR/PMMA and graphene sensors show completely different sensitivities to VOC vapors. The GR/PMMA and graphene sensors showed the highest sensitivities to dichloromethane (DCM). The response of the GR/PMMA sensor to DCM was 3 times higher than that of the graphene sensor but the GR/PMMA sensor hardly responded to acetone, chloroform, or benzene. The sensing mechanism of the graphene sensor can be based on the dielectric constant of VOCs, the size of VOC molecule, and electron hopping effects on defect graphene, while that of the GR/PMMA sensor can be explained in terms of the polymer swelling owing to the Hansen solubility parameter.

Polycrystalline silicon thin-film transistors fabricated by Joule-heating-induced crystallization

NASA Astrophysics Data System (ADS)

Hong, Won-Eui; Ro, Jae-Sang

2015-01-01

Joule-heating-induced crystallization (JIC) of amorphous silicon (a-Si) films is carried out by applying an electric pulse to a conductive layer located beneath or above the films. Crystallization occurs across the whole substrate surface within few tens of microseconds. Arc instability, however, is observed during crystallization, and is attributed to dielectric breakdown in the conductor/insulator/transformed polycrystalline silicon (poly-Si) sandwich structures at high temperatures during electrical pulsing for crystallization. In this study, we devised a method for the crystallization of a-Si films while preventing arc generation; this method consisted of pre-patterning an a-Si active layer into islands and then depositing a gate oxide and gate electrode. Electric pulsing was then applied to the gate electrode formed using a Mo layer. The Mo layer was used as a Joule-heat source for the crystallization of pre-patterned active islands of a-Si films. JIC-processed poly-Si thin-film transistors (TFTs) were fabricated successfully, and the proposed method was found to be compatible with the standard processing of coplanar top-gate poly-Si TFTs.

Effect of molecular mass on supramolecular organisation of poly(4,4''-dioctyl-2,2':5',2''-terthiophene).

PubMed

Jaroch, Tomasz; Knor, Marek; Nowakowski, Robert; Zagórska, Małgorzata; Proń, Adam

2008-10-28

The effect of the chain length on the type and extent of the 2D supramolecular organization in poly(4,4''-dioctyl-2,2':5',2''-terthiophene) (PDOTT) monomolecular layers deposited on highly oriented pyrolytic graphite (HOPG) is studied by scanning tunneling microscopy (STM) and analyzed in terms of molecular modeling. The strictly monodispersed fractions of increasing molecular mass used in this study were obtained by chromatographic fractionation of the crude product of 4,4''-dioctyl-2,2':5',2''-terthiophene oxidative polymerization. STM investigations of PDOTT layers, deposited on HOPG from poly- and monodispersed fractions, show that polydispersity can be considered as a key factor seriously limiting supramolecular ordering. This is a consequence of significant differences in the type of supramolecular order observed for molecules of different chain length. It has been demonstrated that shorter molecules (consisting of 6 and 9 thiophene units) form well-defined two-dimensional islands, while the interactions between longer molecules (consisting of 12 and 15 thiophene units) become anisotropic. Consequently, for higher molecular mass fractions, the supramolecular organization is one-dimensional and consists of more or less separated rows of ordered macromolecules. In this case an increase of the chain length leads to amplification of the intermolecular interactions proceeding via interdigitation of the alkyl substituents of adjacent molecules. Polydispersed fractions show much less ordered organization because of the incompatibility of the supramolecular structures of molecules of different molecular masses. This finding is of crucial importance for the application of polythiophene derivatives in organic and molecular electronics since ordered supramolecular organization constitutes the condition sine qua non of good electrical transport properties.

Crystalline silicon photovoltaics via low-temperature TiO 2/Si and PEDOT/Si heterojunctions

NASA Astrophysics Data System (ADS)

Nagamatsu, Ken Alfred

The most important goals in developing solar cell technology are to achieve high power conversion efficiencies and lower costs of manufacturing. Solar cells based on crystalline silicon currently dominate the market because they can achieve high efficiency. However, conventional p-n junction solar cells require high-temperature diffusions of dopants, and conventional heterojunction cells based on amorphous silicon require plasma-enhanced deposition, both of which can add manufacturing costs. This dissertation investigates an alternative approach, which is to form crystalline-silicon-based solar cells using heterojunctions with materials that are easily deposited at low temperatures and without plasma enhancement, such as organic semiconductors and metal oxides. We demonstrate a heterojunction between the organic polymer, poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT), and crystalline silicon, which acts as a hole-selective contact and an alternative to a diffused p-n junction. We also present the use of a heterojunction between titanium dioxide and crystalline silicon as a passivating electron-selective contact. The Si/TiO2 heterojunction is demonstrated for the first time as a back-surface field in a crystalline silicon solar cell, and is incorporated into a PEDOT/Si device. The resulting PEDOT/Si/TiO2 solar cell represents an alternative to conventional silicon solar cells that rely on thermally-diffused junctions or plasma-deposited heterojunctions. Finally, we investigate the merits of using conductive networks of silver nanowires to enhance the photovoltaic performance of PEDOT/Si solar cells. The investigation of these materials and devices contributes to the growing body of work regarding crystalline silicon solar cells made with selective contacts.

A fractal nature for polymerized laminin.

PubMed

Hochman-Mendez, Camila; Cantini, Marco; Moratal, David; Salmeron-Sanchez, Manuel; Coelho-Sampaio, Tatiana

2014-01-01

Polylaminin (polyLM) is a non-covalent acid-induced nano- and micro-structured polymer of the protein laminin displaying distinguished biological properties. Polylaminin stimulates neuritogenesis beyond the levels achieved by ordinary laminin and has been shown to promote axonal regeneration in animal models of spinal cord injury. Here we used confocal fluorescence microscopy (CFM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) to characterize its three-dimensional structure. Renderization of confocal optical slices of immunostained polyLM revealed the aspect of a loose flocculated meshwork, which was homogeneously stained by the antibody. On the other hand, an ordinary matrix obtained upon adsorption of laminin in neutral pH (LM) was constituted of bulky protein aggregates whose interior was not accessible to the same anti-laminin antibody. SEM and AFM analyses revealed that the seed unit of polyLM was a flat polygon formed in solution whereas the seed structure of LM was highly heterogeneous, intercalating rod-like, spherical and thin spread lamellar deposits. As polyLM was visualized at progressively increasing magnifications, we observed that the morphology of the polymer was alike independently of the magnification used for the observation. A search for the Hausdorff dimension in images of the two matrices showed that polyLM, but not LM, presented fractal dimensions of 1.55, 1.62 and 1.70 after 1, 8 and 12 hours of adsorption, respectively. Data in the present work suggest that the intrinsic fractal nature of polymerized laminin can be the structural basis for the fractal-like organization of basement membranes in the neurogenic niches of the central nervous system.

Performance of Bulk Heterojunction Photovoltaic Devices Prepared by Airbrush Spray Deposition

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

Green, R.; Morfa, A.; Ferguson, A. J.

2008-01-01

We have used airbrush spray deposition to fabricate organic photovoltaic devices with an active layer composed of a blend of poly(3-hexylthiophene) and [6,6]-phenyl-C{sub 61} butyric acid methyl ester. Working devices were prepared in ambient conditions from a variety of common organic solvents; active layers prepared from chlorobenzene exhibit improved homogeneity, resulting in narrower distributions of the relevant device parameters. Further studies on devices prepared from chlorobenzene showed that annealing at 120 C for 10 min resulted in optimum performance, and that an active layer thickness of 150 nm resulted in a maximum efficiency of 2.35% under AM1.5 illumination at 1more » sun.« less

Polyvinylpyrrolidone/Multiwall Carbon Nanotube Composite Based 36° YX LiTaO3 Surface Acoustic Wave For Hydrogen Gas Sensing Applications

NASA Astrophysics Data System (ADS)

Chee, Pei Song; Arsat, Rashidah; He, Xiuli; Kalantar-zadeh, Kourosh; Arsat, Mahyuddin; Wlodarski, Wojtek

2011-05-01

Poly-vinyl-pyrrolidone (PVP) /Multiwall Carbon Nanotubes (MWNTs) based Surface Acoustic Wave (SAW) sensors are fabricated and characterized, and their performances towards hydrogen gas are investigated. The PVP/MWNTs fibers composite are prepared by electrospinning of the composite aqueous solution deposited directly onto the active area of SAW transducers. Via scanning electron microscopy (SEM), the morphology of the deposited nanostructure material is observed. From the dynamic response, frequency shifts of 530 Hz (1% H2) and 11.322 kHz (0.25% H2) are recorded for the sensors contain of 1.525 g and 1.025 g PVP concentrations, respectively.

Polymeric microcapsules assembled from a cationic/zwitterionic pair of responsive block copolymer micelles.

PubMed

Addison, Timothy; Cayre, Olivier J; Biggs, Simon; Armes, Steven P; York, David

2010-05-04

Using a layer-by-layer (LbL) approach, this work presents the preparation of hollow microcapsules with a membrane constructed entirely from a cationic/zwitterionic pair of pH-responsive block copolymer micelles. Our previous work with such systems highlighted that, in order to retain the responsive nature of the individual micelles contained within the multilayer membranes, it is important to optimize the conditions required for the selective dissolution of the sacrificial particulate templates. Consequently, here, calcium carbonate particles have been employed as colloidal templates as they can be easily dissolved in aqueous environments with the addition of chelating agents such as ethylenediaminetetraacetic acid (EDTA). Furthermore, the dissolution can be carried out in solutions buffered to a desirable pH so not to adversely affect the pH sensitive micelles forming the capsule membranes. First, we have deposited alternating layers of anionic poly[2-(dimethylamino)ethyl methacrylate-block-poly(2-(diethylamino)ethyl methacrylate)] (PDMA-PDEA) and cationic poly(2-(diethylamino)ethyl)methacrylate-block-poly(methacrylic acid) (PDEA-PMAA) copolymer micelles onto calcium carbonate colloidal templates. After deposition of five micelle bilayers, addition of dilute EDTA solution resulted in dissolution of the calcium carbonate and formation of hollow polymer capsules. The capsules were imaged using atomic force microscopy (AFM) and scanning electron microscopy (SEM), which shows that the micelle/micelle membrane is sufficiently robust to withstand dissolution of the supporting template. Quartz crystal microbalance studies were conducted and provide good evidence that the micelle multilayer structure is retained after EDTA treatment. In addition, a hydrophobic dye was incorporated into the micelle cores prior to adsorption. After dissolution of the particle template, the resulting hollow capsules retained a high concentration of dye, suggesting that the core/shell structure of the micelles remains intact. Finally, thermogravimetric analysis (TGA) of dried capsules confirmed complete removal of the sacrificial inorganic template. As far as we are aware, this is the first demonstration of LbL assembled capsules composed entirely from responsive block copolymer micelles. The results presented here when combined with our previous findings demonstrate that such systems have potential application in the encapsulation and triggered release of actives.

Low-temperature silicon thin films for large-area electronics: Device fabrication using soft lithography and laser-crystallization by sequential lateral solidification

NASA Astrophysics Data System (ADS)

Jin, Hyun-Chul

This work demonstrates possible routes for fabricating large-area electronic devices on glass or plastic substrates using low-temperature materials deposition and soft lithographic device patterning. Hydrogenated amorphous silicon (a-Si:H) and polycrystalline silicon (poly-Si) have been extensively studied as the semiconducting material for flat panel displays and solar cells. On glass substrates, we have deposited a-Si:H films at a temperature lower than 125°C, and we have used pulsed excimer laser crystallization in the sequential lateral solidification (SLS) regime to fabricate poly-Si films. We use micromolding in capillaries (MIMIC), a form of soft lithography involving micrometer-scale polymer molding, as a means to fabricate amorphous silicon thin-film transistors (TFTs), and photoconductive sensor arrays on both planar and curved substrates. The use of non-planar substrates has captured considerable attention in the field because it would open up new applications and new designs. Field-effect transistors made by SLS poly-Si show excellent mobility and on/off current ratio; however, the microstructure of the material had never been well documented. We determined the microtexture using electron backscattering diffraction (EBSD): the first crystallites formed in the a-Si layer are random; along the direction of the solidification, a strong <100> in-plane orientation quickly develops due to competitive growth and occlusion. The misorientation angle between neighboring grains is also analyzed. A large fraction of the boundaries within the material are low-angle and coincidence site lattice (CSL) types. We discuss the implications of the findings on the defect generation mechanism and on the electrical properties of the films. We have analyzed the electrical properties of SLS poly-Si films on oxidized Si wafer using the pseudo-MOSFET geometry; the majority carrier mobility is extracted from the transconductance. However, the data are non-ideal due to large contact resistance and current spreading. We discuss the future use of these electrical characterization techniques to analyze the properties of individual grain boundaries in thin film Si bicrystals formed by SLS.

Description of extreme-wave deposits on the northern coast of Bonaire, Netherlands Antilles

USGS Publications Warehouse

Watt, Steven G.; Jaffe, Bruce E.; Morton, Robert A.; Richmond, Bruce M.; Gelfencaum, Guy

2010-01-01

To develop a better understanding of the origins of extreme-wave deposits and to help assess the potential risk of future overwash events, a field mapping survey was conducted in November 2006 on the northern coast of Bonaire, Netherlands Antilles. Deposits were mapped and analyzed to help develop a systematic sedimentological approach to distinguish the type of extreme-wave event (tsunamis or storms) or combination of events that formed and modified the deposits over time. Extreme-wave deposits on the northern coast of Bonaire between Boka Onima and Boka Olivia have formed sand sheets, poly-modal ridge complexes, and boulder fields on a Pleistocene limestone platform 3?8 meters above sea level. The deposits exhibit characteristics that are consistent with both large storm and tsunami processes that often overlap one another. Sand sheets occur as low-relief features underlying and incorporated with boulder field deposits. The seaward edge of ridge complexes are deposited up to 70 m from the shoreline and can extend over 200 m inland. Over 600 clasts were measured in fields and range in size from coarse gravel to fine block, weigh up to 165 metric tons, and are placed over 280 m from the shoreline. Our analyses indicate that the deposits may have been produced by a combination of hurricane and tsunami events spanning 10s to 1000s of years. Comparing the different deposit morphologies between study sites highlights the importance of shoreline orientation to the distribution of extreme-wave deposits onshore. However, further investigation is required to fully understand the processes that have produced and modified these deposits over time.

Enhanced Column Filtration for Arsenic Removal from Water: Polymer-Templated Iron Oxide Nanoparticles Immobilized on Sand via Layer-by-Layer Deposition

NASA Astrophysics Data System (ADS)

Cheng, Calvin Chia-Hung

Arsenic is ubiquitous in water sources around the world and is highly toxic. While precipitation and membrane filtration techniques are successfully implemented in developed cities, they are unsuitable for rural and low-resource settings lacking centralized facilities. This thesis presents the use of ultra-small iron oxide (Fe2O3) nanoparticles functionalized on sand granules for use as a house-hold scale adsorption filter. Water-stable alpha-Fe2O3 (hematite) nanoparticles (<10 nm) were synthesized via a collapsed-polymer approach using poly(acrylic acid) and Fe3+ ions. The nanoparticles exhibited high arsenic adsorption, with 147 +/- 2 mg As(III) per g Fe2O3 and 91 +/- 10 mg As(V) per g Fe2O3. The platform was also used to synthesize iron-based composites, including magnetite (Fe 3O4) and Fe-Cu oxide nanoparticles. For use as a column filter, Fe2O3-PAA nanoparticles were functionalized on sand granules using a layer-by-layer deposition method, with the nanoparticles embedded in the negative layer. The removal of As(III) by the Fe2O 3-PAA functionalized column was described by reversible 1st order kinetics where the forward and reverse rate constants were 0.31 hr -1 and 0.097 hr-1, respectively. Implemented as a passive water filter with 30 x 30 x 50 cm3 dimensions, the filter has an expected lifetime in the order of many years. By controlling the flow rate of the column depending on contamination levels, the filter effectively removes arsenic down to the safety limit of 0.01 mg/L. In a parallel project, the layer-by-layer deposition of Poly(diallydimethyl ammonium chloride) (PDDA) and poly(sodium 5-styrenesulfonate) (PSS) was exploited for a highly practical synthesis of discrete gradient surfaces. By independently controlling the concentration of NaCl in PDDA and PSS deposition solutions, a 2-dimensional matrix of surfaces was created in 96-well microtiter plates. Distinct non-monotonic dye adsorption patterns on the gradient surfaces was observed. Practical knowledge from this project was also used to enhance the nanoparticle surface functionalization described above. In all, a practical, no expertise-needed passive water filtration unit was described in this thesis. The unit makes use of hardware available in existing sand-based water filters, and is designed to address the unmet need of arsenic removal from drinking water in low-resource or rural settings.

One-step route to the fabrication of highly porous polyaniline nanofiber films by using PS-b-PVP diblock copolymers as templates.

PubMed

Li, Xue; Tian, Shengjun; Ping, Yang; Kim, Dong Ha; Knoll, Wolfgang

2005-10-11

We report a new method to control both the nucleation and growth of highly porous polyaniline (PANI) nanofiber films using porous poly(styrene-block-2-vinylpyridine) diblock copolymer (PS-b-P2VP) films as templates. A micellar thin film composed of P2VP spheres within a PS matrix is prepared by spin coating a PS-b-P2VP micellar solution onto substrates. The P2VP domains are swollen in a selective solvent of acetic acid, which results in the formation of pores in the block copolymer film. PANI is then deposited onto the substrates modified with such a porous film using electrochemical methods. During the deposition, the nucleation and growth of PANI occur only at the pores of the block copolymer film. After the continued growth of PANI by the electrochemical deposition, a porous PANI nanofiber film is obtained.

Mechanical properties of ultrahigh molecular weight PHEMA hydrogels synthesized using initiated chemical vapor deposition.

PubMed

Bose, Ranjita K; Lau, Kenneth K S

2010-08-09

In this work, poly(2-hydroxyethyl methacrylate) (PHEMA), a widely used hydrogel, is synthesized using initiated chemical vapor deposition (iCVD), a one-step surface polymerization that does not use any solvents. iCVD synthesis is capable of producing linear stoichiometric polymers that are free from entrained unreacted monomer or solvent and, thus, do not require additional purification steps. The resulting films, therefore, are found to be noncytotoxic and also have low nonspecific protein adsorption. The kinetics of iCVD polymerization are tuned so as to achieve rapid deposition rates ( approximately 1.5 microm/min), which in turn yield ultrahigh molecular weight polymer films that are mechanically robust with good water transport and swellability. The films have an extremely high degree of physical chain entanglement giving rise to high tensile modulus and storage modulus without the need for chemical cross-linking that compromises hydrophilicity.

Comparison of precursor infiltration into polymer thin films via atomic layer deposition and sequential vapor infiltration using in-situ quartz crystal microgravimetry

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

Padbury, Richard P.; Jur, Jesse S., E-mail: jsjur@ncsu.edu

Previous research exploring inorganic materials nucleation behavior on polymers via atomic layer deposition indicates the formation of hybrid organic–inorganic materials that form within the subsurface of the polymer. This has inspired adaptations to the process, such as sequential vapor infiltration, which enhances the diffusion of organometallic precursors into the subsurface of the polymer to promote the formation of a hybrid organic–inorganic coating. This work highlights the fundamental difference in mass uptake behavior between atomic layer deposition and sequential vapor infiltration using in-situ methods. In particular, in-situ quartz crystal microgravimetry is used to compare the mass uptake behavior of trimethyl aluminummore » in poly(butylene terephthalate) and polyamide-6 polymer thin films. The importance of trimethyl aluminum diffusion into the polymer subsurface and the subsequent chemical reactions with polymer functional groups are discussed.« less

Parylene C as a Sacrificial Material for Microfabrication

NASA Technical Reports Server (NTRS)

Beamesderfer, Michael

2005-01-01

Parylene C has been investigated for use as a sacrificial material in microfabrication. Although Parylene C cannot be patterned lithographically like photoresists, it nevertheless extends the range of processing options by offering a set of properties that are suitable for microfabrication and are complementary to those of photoresists. The compatibility of Parylene C with several microfabrication processes was demonstrated in experiments in which a thin film of Parylene C was deposited on a silicon wafer, then several thin metal films were deposited and successfully patterned, utilizing the Parylene C pads as a sacrificial layer. The term "parylene" -- a contraction of "poly(para-xylene)" -- denotes a family of vapor-deposited polymers. In Parylene C (the most common form of parylene), a chlorine atom is substituted for one of the hydrogen atoms on the benzene ring of each para-xylene moiety. Heretofore, parylenes have been used as conformal coating materials in diverse applications.

Electromigration and Deposition of Micro-Scale Calcium Carbonate Structures with Controlled Morphology and Polymorphism

DTIC Science & Technology

2013-04-01

precipitation of calcium carbonate in structured templates including microporous polycarbonate membranes and polyethylene foams. Para- meters...polyethylene foam). Microporous polycarbonate membranes and Medium-Density PolyEthylene (MDPE) foam specimens were used as the porous organic...voids in hardened concrete. DOI:10.1520/C624-06. West Conshohocken, PA: ASTM International . www.astm.org. Bersa, L., and M. Liu. 2007. A review on

Investigation on the formation process of single-crystalline GaO x barrier in Fe/GaO x /MgO/Fe magnetic tunnel junctions

NASA Astrophysics Data System (ADS)

Krishna, N. S.; Doko, N.; Matsuo, N.; Saito, H.; Yuasa, S.

2017-11-01

We have grown Fe(0 0 1)/GaO x (0 0 1)/MgO(0 0 1)/Fe(0 0 1) magnetic tunnel junctions (MTJs) with or without in situ annealing after the deposition of GaO x layer and performed structural characterizations by focusing on the formation process of the single-crystalline GaO x . It was found that, even without the in situ annealing, the as-grown GaO x grown on the MgO was mostly single-crystalline except near the surface region (amorphous). The crystallization temperature of the amorphous region was reduced from 500 °C down to 250 °C by depositing the Fe upper electrode (poly-crystalline). It was clarified that the crystallization of the amorphous region near the Fe/GaO x interface caused the realignments of the crystal grains in the poly-crystalline Fe upper electrode, and, as a result, the fully epitaxial Fe/GaO x /MgO/Fe structure is eventually formed. All the MTJs showed high tunneling magnetoresistance ratios (about 100%) at room temperature, which was almost independent of the formation temperature of the single-crystalline GaO x .

Fabrication of complex free-standing nanostructures with concave and convex curvature via the layer-by-layer approach.

PubMed

Raoufi, Mohammad; Schönherr, Holger

2014-02-18

We report on the fabrication of unprecedented free-standing complex polymeric nanoobjects, which possess both concave and convex curvatures, by exploiting the layer-by-layer (LBL) deposition of polyelectrolytes. In a combined top-down/bottom-up replication approach pore diameter-modulated anodic aluminum oxide (AAO) templates, fabricated by temperature modulation hard anodization (TMHA), were replicated with multilayers of poly(styrene sulfonate) (PSS) and poly(allylamine hydrochloride) (PAH) to yield open nanotubes with diameters in the wide and narrow segments of 210 and 150 nm, respectively. To obtain stable pore diameter-modulated nanopores, which possess segment lengths between 1 and 5 μm and 5 and 10 μm in the narrow and wide pore portion, respectively, conventional hard anodization of aluminum was followed by a subsequent temperature-modulated anodization. After removing the backside aluminum electrode, silanizing the aluminum oxide, and passivating the exposed membrane surface with a thin layer of gold, PSS and PAH were deposited alternatingly to yield LBL multilayers. For optimized LBL multilayer thicknesses and compactness, established in separate experiments on silicon substrates and nanoporous AAO with straight pores, free-standing polymeric nanoobjects with concave and convex curvatures, were obtained. These were stable for wall thickness to pore diameter ratios of ≥0.08.

Desalination by Membrane Distillation using Electrospun Polyamide Fiber Membranes with Surface Fluorination by Chemical Vapor Deposition.

PubMed

Guo, Fei; Servi, Amelia; Liu, Andong; Gleason, Karen K; Rutledge, Gregory C

2015-04-22

Fibrous membranes of poly(trimethyl hexamethylene terephthalamide) (PA6(3)T) were fabricated by electrospinning and rendered hydrophobic by applying a conformal coating of poly(1H,1H,2H,2H-perfluorodecyl acrylate) (PPFDA) using initiated chemical vapor deposition (iCVD). A set of iCVD-treated electrospun PA6(3)T fiber membranes with fiber diameters ranging from 0.25 to 1.8 μm were tested for desalination using the air gap membrane distillation configuration. Permeate fluxes of 2-11 kg/m2/h were observed for temperature differentials of 20-45 °C between the feed stream and condenser plate, with rejections in excess of 99.98%. The liquid entry pressure was observed to increase dramatically, from 15 to 373 kPa with reduction in fiber diameter. Contrary to expectation, for a given feed temperature the permeate flux was observed to increase for membranes of decreasing fiber diameter. The results for permeate flux and salt rejection show that it is possible to construct membranes for membrane distillation even from intrinsically hydrophilic materials after surface modification by iCVD and that the fiber diameter is shown to play an important role on the membrane distillation performance in terms of permeate flux, salt rejection, and liquid entry pressure.

Electrospun sulfonated poly(ether ketone) nanofibers as proton conductive reinforcement for durable Nafion composite membranes

NASA Astrophysics Data System (ADS)

Klose, Carolin; Breitwieser, Matthias; Vierrath, Severin; Klingele, Matthias; Cho, Hyeongrae; Büchler, Andreas; Kerres, Jochen; Thiele, Simon

2017-09-01

We show that the combination of direct membrane deposition with proton conductive nanofiber reinforcement yields highly durable and high power density fuel cells. Sulfonated poly(ether ketone) (SPEK) was directly electrospun onto gas diffusion electrodes and then filled with Nafion by inkjet-printing resulting in a 12 μm thin membrane. The ionic membrane resistance (30 mΩ*cm2) was well below that of a directly deposited membrane reinforced with chemically inert (PVDF-HFP) nanofibers (47 mΩ*cm2) of comparable thickness. The power density of the fuel cell with SPEK reinforced membrane (2.04 W/cm2) is 30% higher than that of the PVDF-HFP reinforced reference sample (1.57 W/cm2). During humidity cycling and open circuit voltage (OCV) hold, the SPEK reinforced Nafion membrane showed no measurable degradation in terms of H2 crossover current density, thus fulfilling the target of 2 mA/cm2 of the DOE after degradation. The chemical accelerated stress test (100 h OCV hold at 90 °C, 30% RH, H2/air, 50/50 kPa) revealed a degradation rate of about 0.8 mV/h for the fuel cell with SPEK reinforced membrane, compared to 1.0 mV/h for the PVDF-HFP reinforced membrane.

Optimization of the electrodeposition of copper on poly-1-naphthylamine for the amperometric detection of carbohydrates in HPLC.

PubMed

D'Eramo, Fabiana; Marioli, Juan M; Arévalo, Alejandro H; Sereno, Leonides E

2003-11-04

A modified electrode consisting of copper dispersed in a poly-1-naphthylamine (p-1-NAP/Cu) film on a glassy carbon electrode was used as an amperometric detector for the on-line analysis of various carbohydrates separated by high performance liquid chromatography. The results obtained with this new sensor were compared to those obtained with a modified electrode based on the same polymer but with copper ions incorporated at open circuit, as described in a previous paper. In this new modified electrode the copper microparticles were electrochemically deposited into the polymeric matrix by single potential step chronoamperometry. A nucleation and growth mechanism was proposed to explain the current transients of copper electrodeposition. The experimental results were fitted to the proposed mechanism by using a mathematical equation that considers three-dimensional growth and progressive nucleation, assuming a no overlap and no diffusion mechanism. Cyclic voltammetric experiments showed that the electrodeposited copper microparticles provided a catalytic surface suited for the oxidation of glucose and several carbohydrates. The sensitivity of the electrode was influenced by the amount of copper electrodeposited, which in turn depended on the applied overpotential used for the deposition of copper. Liquid chromatographic experiments were carried out to test the analytical performance of these electrodes for the determination of various carbohydrates.

Protein-resistant polymer coatings obtained by matrix assisted pulsed laser evaporation

NASA Astrophysics Data System (ADS)

Rusen, L.; Mustaciosu, C.; Mitu, B.; Filipescu, M.; Dinescu, M.; Dinca, V.

2013-08-01

Adsorption of proteins and polysaccharides is known to facilitate microbial attachment and subsequent formation of biofilm on surfaces that ultimately results in its biofouling. Therefore, protein repellent modified surfaces are necessary to block the irreversible attachment of microorganisms. Within this context, the feasibility of using the Poly(ethylene glycol)-block-poly(ɛ-caprolactone) methyl ether (PEG-block-PCL Me) copolymer as potential protein-resistant coating was explored in this work. The films were deposited using Matrix Assisted Pulsed Laser Evaporation (MAPLE), a technique that allows good control of composition, thickness and homogeneity. The chemical and morphological characteristics of the films were examined using Fourier Transform Infrared Spectroscopy (FTIR), contact angle measurements and Atomic Force Microscopy (AFM). The FTIR data demonstrates that the functional groups in the MAPLE-deposited films remain intact, especially for fluences below 0.5 J cm-2. Optical Microscopy and AFM images show that the homogeneity and the roughness of the coatings are related to both laser parameters (fluence, number of pulses) and target composition. Protein adsorption tests were performed on the PEG-block-PCL Me copolymer coated glass and on bare glass surface as a control. The results show that the presence of copolymer as coating significantly reduces the adsorption of proteins.

Solution-derived SiO2 gate insulator formed by CO2 laser annealing for polycrystalline silicon thin-film transistors

NASA Astrophysics Data System (ADS)

Hishitani, Daisuke; Horita, Masahiro; Ishikawa, Yasuaki; Ikenoue, Hiroshi; Uraoka, Yukiharu

2017-05-01

The formation of perhydropolysilazane (PHPS)-based SiO2 films by CO2 laser annealing is proposed. Irradiation with a CO2 laser with optimum fluence transformed a prebaked PHPS film into a SiO2 film with uniform composition in the thickness direction. Polycrystalline silicon thin-film transistors (poly-Si TFTs) with a SiO2 film as the gate insulator were fabricated. When the SiO2 film was formed by CO2 laser annealing (CO2LA) at the optimum fluence of 20 mJ/cm2, the film had fewer OH groups which was one-twentieth that of the furnace annealed PHPS film and one-hundredth that of the SiO2 film deposited by plasma-enhanced chemical vapor deposition (PECVD) using tetraethyl orthosilicate (TEOS). The resulting TFTs using PHPS showed a clear transistor operation with a field-effect mobility of 37.9 ± 1.2 cm2 V-1 s-1, a threshold voltage of 9.8 ± 0.2 V, and a subthreshold swing of 0.76 ± 0.02 V/decade. The characteristics of such TFTs were as good as those of a poly-Si TFT with a SiO2 gate insulator prepared by PECVD using TEOS.

Bulk-heterojunction organic solar cells sandwiched by solution processed molybdenum oxide and titania nanosheet layers

NASA Astrophysics Data System (ADS)

Itoh, Eiji; Goto, Yoshinori; Fukuda, Katsutoshi

2014-02-01

The contributions of ultrathin titania nanosheet (TN) crystallites were studied in both an inverted bulk-heterojunction (BHJ) cell in an indium-tin oxide (ITO)/titania nanosheet (TN)/poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methylester (PCBM) active layer/MoOx/Ag multilayered photovoltaic device and a conventional BHJ cell in ITO/MoOx/P3HT:PCBM active layer/TN/Al multilayered photovoltaic device. The insertion of only one or two layers of poly(diallyldimethylammonium chloride) (PDDA) and TN multilayered film prepared by the layer-by-layer deposition technique effectively decreased the leakage current and increased the open circuit voltage (VOC), fill factor (FF), and power conversion efficiency (η). The conventional cell sandwiched between a solution-processed, partially crystallized molybdenum oxide hole-extracting buffer layer and a TN electron extracting buffer layer showed comparable cell performance to a device sandwiched between vacuum-deposited molybdenum oxide and TN layers, whereas the inverted cell with solution-processed molybdenum oxide showed a poorer performance probably owing to the increment in the leakage current across the film. The abnormal S-shaped curves observed in the inverted BHJ cell above VOC disappeared with the use of a polyfluorene-based cationic semiconducting polymer as a substitute for an insulating PDDA film, resulting in the improved cell performance.

Biomimetic poly(lactide) based fibrous scaffolds for ligament tissue engineering.

PubMed

Surrao, Denver C; Waldman, Stephen D; Amsden, Brian G

2012-11-01

The aim of this study was to fabricate a fibrous scaffold that closely resembled the micro-structural architecture and mechanical properties of collagen fibres found in the anterior cruciate ligament (ACL). To achieve this aim, fibrous scaffolds were made by electrospinning L-lactide based polymers. L-Lactide was chosen primarily due to its demonstrated biocompatibility, biodegradability and high modulus. The electrospun fibres were collected in tension on a rotating wire mandrel. Upon treating these fibres in a heated aqueous environment, they possessed a crimp-like pattern having a wavelength and amplitude similar to that of native ACL collagen. Of the polymer fibre scaffolds studied, those made from poly(L-lactide-co-D,L-lactide) PLDLA exhibited the highest modulus and were also the most resilient to in vitro hydrolytic degradation, undergoing a slight decrease in modulus compared to the other polymeric fibres over a 6 month period. Bovine fibroblasts seeded on the wavy, crimp-like PLDLA fibres attached, proliferated and deposited extracellular matrix (ECM) molecules on the surface of the fibrous scaffold. In addition, the deposited ECM exhibited bundle formation that resembled the fascicles found in native ACL. These findings demonstrate the importance of replicating the geometric microenvironment in developing effective tissue engineering scaffolds. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Synthesis of Macroporous Poly(dimethylsiloxane) Scaffolds for Tissue Engineering Applications

PubMed Central

Pedraza, Eileen; Brady, Ann-Christina; Fraker, Christopher A.

2015-01-01

Macroporous, biostable scaffolds with controlled porous architecture were prepared from poly(dimethylsiloxane) (PDMS) using sodium chloride particles (NaCl) and a solvent casting and particulate leaching (SCPL) technique. The effect of particulate size range and overall porosity on the resulting structure was evaluated. Results found 90% v/v scaffolds and particulate ranges above 100 µm to have the most optimal open framework and porosity. Resulting hydrophobic PDMS scaffolds were coated with fibronectin and evaluated as a platform for adherent cell culture using human mesenchymal stem cells. Biocompatibility of PDMS scaffolds was also evaluated in a rodent model, where implants were found to be highly biocompatibile and biostable, with positive extracellular matrix deposition throughout the scaffold. These results demonstrate the suitability of macroporous PDMS scaffolds for tissue engineering applications where strong integration with the host is desired. PMID:23683037

Formation of a Polycrystalline Silicon Thin Film by Using Blue Laser Diode Annealing

NASA Astrophysics Data System (ADS)

Choi, Young-Hwan; Ryu, Han-Youl

2018-04-01

We report the crystallization of an amorphous silicon thin film deposited on a SiO2/Si wafer using an annealing process with a high-power blue laser diode (LD). The laser annealing process was performed using a continuous-wave blue LD of 450 nm in wavelength with varying laser output power in a nitrogen atmosphere. The crystallinity of the annealed poly-silicon films was investigated using ellipsometry, electron microscope observation, X-ray diffraction, and Raman spectroscopy. Polysilicon grains with > 100-nm diameter were observed to be formed after the blue LD annealing. The crystal quality was found to be improved as the laser power was increased up to 4 W. The demonstrated blue LD annealing is expected to provide a low-cost and versatile solution for lowtemperature poly-silicon processes.

Atomic-resolution characterization of the effects of CdCl2 treatment on poly-crystalline CdTe thin films

NASA Astrophysics Data System (ADS)

Paulauskas, T.; Buurma, C.; Colegrove, E.; Guo, Z.; Sivananthan, S.; Chan, M. K. Y.; Klie, R. F.

2014-08-01

Poly-crystalline CdTe thin films on glass are used in commercial solar-cell superstrate devices. It is well known that post-deposition annealing of the CdTe thin films in a CdCl2 environment significantly increases the device performance, but a fundamental understanding of the effects of such annealing has not been achieved. In this Letter, we report a change in the stoichiometry across twin boundaries in CdTe and propose that native point defects alone cannot account for this variation. Upon annealing in CdCl2, we find that the stoichiometry is restored. Our experimental measurements using atomic-resolution high-angle annular dark field imaging, electron energy-loss spectroscopy, and energy dispersive X-ray spectroscopy in a scanning transmission electron microscope are supported by first-principles density functional theory calculations.

Silver Nanowires Modified with PEDOT: PSS and Graphene for Organic Light-Emitting Diodes Anode

PubMed Central

Xu, Yilin; Wei, Xiang; Wang, Cong; Cao, Jin; Chen, Yigang; Ma, Zhongquan; You, Ying; Wan, Jixiang; Fang, Xiaohong; Chen, Xiaoyuan

2017-01-01

Silver nanowires (AgNWs) networks are promising candidates for the replacement of indium tin oxide (ITO). However, the surface roughness of the AgNWs network is still too high for its application in optoelectronic devices. In this work, we have reduced the surface roughness of the AgNWs networks to 6.4 nm, compared to 33.9 nm of the as-deposited AgNWs network through the hot-pressing process, treatment with poly (3,4ethylenedioxythiophene)–poly (styrenesulfanate), and covered with graphene films. Using this method, we are able to produce AgNWs/PEDOT: PSS/SLG composite films with the transmittance and sheet resistance of 88.29% and 30 Ω/□, respectively. The OLEDs based on the AgNWs/PEDOT: PSS/SLG anodes are comparable to those based on ITO anodes. PMID:28349990

In vivo polymerization of poly(3,4-ethylenedioxythiophene) in the living rat hippocampus does not cause a significant loss of performance in a delayed alternation task

NASA Astrophysics Data System (ADS)

Ouyang, Liangqi; Shaw, Crystal L.; Kuo, Chin-chen; Griffin, Amy L.; Martin, David C.

2014-04-01

After extended implantation times, traditional intracortical neural probes exhibit a foreign-body reaction characterized by a reactive glial sheath that has been associated with increased system impedance and signal deterioration. Previously, we have proposed that the local in vivo polymerization of an electronically and ionically conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), might help to rebuild charge transport pathways across the glial scar between the device and surrounding parenchyma (Richardson-Burns et al 2007 J. Neural Eng. 4 L6-13). The EDOT monomer can be delivered via a microcannula/electrode system into the brain tissue of living animals followed by direct electrochemical polymerization, using the electrode itself as a source of oxidative current. In this study, we investigated the long-term effect of local in vivo PEDOT deposition on hippocampal neural function and histology. Rodent subjects were trained on a hippocampus-dependent task, delayed alternation (DA), and implanted with the microcannula/electrode system in the hippocampus. The animals were divided into four groups with different delay times between the initial surgery and the electrochemical polymerization: (1) control (no polymerization), (2) immediate (polymerization within 5 min of device implantation), (3) early (polymerization within 3-4 weeks after implantation) and (4) late (polymerization 7-8 weeks after polymerization). System impedance at 1 kHz was recorded and the tissue reactions were evaluated by immunohistochemistry. We found that under our deposition conditions, PEDOT typically grew at the tip of the electrode, forming an ˜500 µm cloud in the tissue. This is much larger than the typical width of the glial scar (˜150 µm). After polymerization, the impedance amplitude near the neurologically important frequency of 1 kHz dropped for all the groups; however, there was a time window of 3-4 weeks for an optimal decrease in impedance. For all surgery-polymerization time intervals, the polymerization did not cause significant deficits in performance of the DA task, suggesting that hippocampal function was not impaired by PEDOT deposition. However, GFAP+ and ED-1+ cells were also found at the deposition two weeks after the polymerization, suggesting potential secondary scarring. Therefore, less extensive deposition or milder deposition conditions may be desirable to minimize this scarring while maintaining decreased system impedance.

In vivo polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) in living rat hippocampus does not cause a significant loss of performance in a delayed alternation (DA) task

PubMed Central

Ouyang, Liangqi; Shaw, Crystal L.; Kuo, Chin-chen; Griffin, Amy L.; Martin, David C.

2014-01-01

After extended implantation times, traditional intracortical neural probes exhibit a foreign body reaction characterized by a reactive glial sheath that has been associated with increased system impedance and signal deterioration. Previously, we have proposed that the local in vivo polymerization of an electronically and ionically conducting polymer, poly(3,4 ethylene dioxythiophene) (PEDOT), might help to rebuild charge transport pathways across the glial scar between the device and surrounding parenchyma (Richardson-Burns, Hendricks, & Martin, 2007). The EDOT monomer can be delivered via a microcannula/electrode system into the brain tissue of living animals followed by direct electrochemical polymerization, using the electrode itself as a source of oxidative current. In this study we investigated the long-term effect of local in vivo PEDOT deposition on hippocampal neural function and histology. Rodent subjects were trained on a hippocampus-dependent task, Delayed Alternation (DA), and implanted with the microcannula/electrode system in the hippocampus. The animals were divided into four groups with different delay times between the initial surgery and the electrochemical polymerization: (1) Control (no polymerization), (2) Immediate (polymerization within 5 minutes of device implantation), (3) Early (polymerization within 3–4 weeks after implantation), and (4) Late (polymerization 7–8 weeks after polymerization). System impedance at 1 kHz was recorded and the tissue reactions were evaluated by immunohistochemistry. We found that under our deposition conditions, PEDOT typically grew at the tip of the electrode, forming a ~500 μm cloud into the tissue. This is much larger than the typical width of the glial scar (~150 μm). After polymerization, the impedance amplitude near the neurologically important frequency of 1 kHz dropped for all the groups, however, there was a time window of 3–4 weeks for optimal decrease in impedance. For all surgery-polymerization time intervals, the polymerization did not cause significant deficits in performance of the DA task, suggesting that hippocampal function was not impaired by PEDOT deposition. However, GFAP+ and ED-1+ cells were also found at the deposition 2 weeks after the polymerization, suggesting potential secondary scarring. Therefore less extensive deposition or milder deposition conditions may be desirable to minimize this scarring while maintaining decreased system impedance. PMID:24503720

Functional Micrococcus lysodeikticus layers deposited by laser technique for the optical sensing of lysozyme.

PubMed

Dinca, Valentina; Zaharie-Butucel, Diana; Stanica, Luciana; Brajnicov, Simona; Marascu, Valentina; Bonciu, Anca; Cristocea, Andra; Gaman, Laura; Gheorghiu, Mihaela; Astilean, Simion; Vasilescu, Alina

2018-02-01

Whole cell optical biosensors, made by immobilizing whole algal, bacterial or mammalian cells on various supports have found applications in several fields, from ecology and ecotoxicity testing to biopharmaceutical production or medical diagnostics. We hereby report the deposition of functional bacterial layers of Micrococcus lysodeikticus (ML) via Matrix-Assisted Pulsed Laser Evaporation (MAPLE) on poly(diallyldimethylamonium) (PDDA)-coated-glass slides and their application as an optical biosensor for the detection of lysozyme in serum. Lysozyme is an enzyme upregulated in inflammatory diseases and ML is an enzymatic substrate for this enzyme. The MAPLE-deposited bacterial interfaces were characterised by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Fourier-Transformed Infrared Spectroscopy (FTIR), Raman and optical microscopy and were compared with control interfaces deposited via layer-by-layer on the same substrate. After MAPLE deposition and coating with graphene oxide (GO), ML-modified interfaces retained their functionality and sensitivity to lysozyme's lytic action. The optical biosensor detected lysozyme in undiluted serum in the clinically relevant range up to 10μgmL -1 , in a fast and simple manner. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis and Application of Ferroelectric Poly(Vinylidene Fluoride-co-Trifluoroethylene) Films using Electrophoretic Deposition

PubMed Central

Ryu, Jeongjae; No, Kwangsoo; Kim, Yeontae; Park, Eugene; Hong, Seungbum

2016-01-01

In this study, we investigated the deposition kinetics of polyvinylidene fluoride copolymerized with trifluoroethylene (P(VDF-TrFE)) particles on stainless steel substrates during the electrophoretic deposition (EPD) process. The effect of applied voltage and deposition time on the structure and ferroelectric property of the P(VDF-TrFE) films was studied in detail. A method of repeated EPD and heat treatment above melting point were employed to fabricate crack-free P(VDF-TrFE) thick films. This method enabled us to fabricate P(VDF-TrFE) films with variable thicknesses. The morphology of the obtained films was investigated by scanning electron microscopy (SEM), and the formation of β-phase was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. P(VDF-TrFE) films prepared with various thicknesses showed remnant polarization (Pr) of around 4 μC/cm2. To demonstrate the applicability of our processing recipe to complex structures, we fabricated a spring-type energy harvester by depositing P(VDF-TrFE) films on stainless steel springs using EPD process. Our preliminary results show that an electrophoretic deposition can be applied to produce high-quality P(VDF-TrFE) films on planar as well as three-dimensional (3-D) substrates. PMID:27805008

Synthesis and application of ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) films using electrophoretic deposition

DOE PAGES

Ryu, Jeongjae; No, Kwangsoo; Kim, Yeontae; ...

2016-11-02

In this paper, we investigated the deposition kinetics of polyvinylidene fluoride copolymerized with trifluoroethylene (P(VDF-TrFE)) particles on stainless steel substrates during the electrophoretic deposition (EPD) process. The effect of applied voltage and deposition time on the structure and ferroelectric property of the P(VDF-TrFE) films was studied in detail. A method of repeated EPD and heat treatment above melting point were employed to fabricate crack-free P(VDF-TrFE) thick films. This method enabled us to fabricate P(VDF-TrFE) films with variable thicknesses. The morphology of the obtained films was investigated by scanning electron microscopy (SEM), and the formation of β-phase was confirmed by X-raymore » diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. P(VDF-TrFE) films prepared with various thicknesses showed remnant polarization (P r) of around 4 μC/cm 2. To demonstrate the applicability of our processing recipe to complex structures, we fabricated a spring-type energy harvester by depositing P(VDF-TrFE) films on stainless steel springs using EPD process. Our preliminary results show that an electrophoretic deposition can be applied to produce high-quality P(VDF-TrFE) films on planar as well as three-dimensional (3-D) substrates.« less

Pretreatment of poly(l-lactide-co-glycolide) scaffolds with sodium hydroxide enhances osteoblastic differentiation and slows proliferation of mouse preosteoblast cells.

PubMed

Carpizo, Katherine H; Saran, Madeleine J; Huang, Weibiao; Ishida, Kenji; Roostaeian, Jason; Bischoff, David; Huang, Catherine K; Rudkin, George H; Yamaguchi, Dean T; Miller, Timothy A

2008-02-01

Surface topography is important in the creation of a scaffold for tissue engineering. Chemical etching of poly(l-lactide-co-glycolide) with sodium hydroxide has been shown to enhance adhesion and function of numerous cell types. The authors investigated the effects of sodium hydroxide pretreatment of three-dimensional poly(l-lactide-co-glycolide) scaffolds on the adhesion, differentiation, and proliferation of MC3T3-E1 murine preosteoblasts. MC3T3-E1 cells were seeded onto three-dimensional poly(l-lactide-co-glycolide) scaffolds with and without 1 M sodium hydroxide pretreatment. Cells were then cultured in osteogenic medium and harvested at varying time points for RNA extraction. Quantitative real-time reverse-transcriptase polymerase chain reaction was performed to measure mRNA expression of several osteogenic marker genes. In addition, cell numbers were determined at varying time points during the culture period. All experiments were performed in triplicate. Pretreatment of three-dimensional poly(l-lactide-co-glycolide) scaffolds with sodium hydroxide resulted in statistically significant up-regulation of mRNA expression of alkaline phosphatase, bone sialoprotein, osteocalcin, and vascular endothelial growth factor during the first 10 days of culture. Histologic analysis demonstrated a striking increase in mineralized cell matrix deposition in the sodium hydroxide-treated group. Cell number was statistically higher in the sodium hydroxide-treated group immediately after cell seeding, suggesting improved adhesion. During the first 24 hours of culture, cells grew faster in the control group than in the sodium hydroxide-treated group. Chemical etching of poly(l-lactide-co-glycolide) scaffolds with sodium hydroxide strongly influences the behavior of MC3T3-E1 preosteoblasts in vitro by enhancing adhesion and differentiation and slowing proliferation. Sodium hydroxide treatment may represent a simple and inexpensive way of improving scaffolds for use in bone tissue engineering.

Organic inorganic hybrid coating (poly(methyl methacrylate)/monodisperse silica)

NASA Astrophysics Data System (ADS)

Rubio, E.; Almaral, J.; Ramírez-Bon, R.; Castaño, V.; Rodríguez, V.

2005-04-01

Polymethylmethacrylate-silica hybrid coatings were prepared from methyl methacrylate and monodisperse colloidal silica prepared by the Stöber method. The surfaces of the spheres were successfully modified by chemical reaction with 3-(trimethoxysilyl) propyl methacrylate (TMSPM) to compatibilise the organic and inorganic components of the precursor solution mixture. The coatings were deposited by dip-coating on glass substrates. They result with good properties of homogeneity, optical transparence, hardness and adhesion.

Dissipation pattern of flubendiamide residues on capsicum fruit (Capsicum annuum L.) under field and controlled environmental conditions.

PubMed

Buddidathi, Radhika; Mohapatra, Soudamini; Siddamallaiah, Lekha; Manikrao, Gourishankar; Hebbar, Shibara Shankara

2016-01-01

This investigation was undertaken to compare the dissipation pattern of flubendiamide in capsicum fruits under poly-house and open field after giving spray applications at the recommended and double doses of 48 g a.i. ha(-1) and 96 g a.i. ha(-1). Extraction and purification of capsicum fruit samples were carried out by the QuEChERS method. Residues of flubendiamide and its metabolite, des-iodo flubendiamide, were analyzed by high-performance liquid chromatography-photodiode array, and confirmed by liquid chromatography-mass spectrometry/mass spectrometry. Limit of quantification of the method was 0.05 mg kg(-1), and recovery of the insecticides was in the range of 89.6-104.3%, with relative standard deviation being 4.5-11.5%. The measurement uncertainty of the analytical method was in the range of 10.7-15.7%. Initial residue deposits of flubendiamide on capsicum fruits grown under poly-house conditions were (0.977 and 1.834 mg kg(-1)) higher than that grown in the field (0.665 and 1.545 mg kg(-1)). Flubendiamide residues persisted for 15 days in field-grown and for 25 days in poly-house-grown capsicum fruits. The residues were degraded with the half-lives of 4.3-4.7 and 5.6-6.6 days in field and poly-house respectively. Des-iodo flubendiamide was not detected in capsicum fruits or soil. The residues of flubendiamide degraded to below the maximum residue limit notified by Codex Alimentarius Commission (FAO/WHO) after 1 and 6 days in open field, and 3 and 10 days in poly-house. The results of the study indicated that flubendiamide applied to capsicum under controlled environmental conditions required longer pre-harvest interval to allow its residues to dissipate to the safe level.

Adsorption of Poly(ethylene oxide)-Poly(lactide) Copolymers. Effects of Composition and Degradation.

PubMed

Muller, Dries; Carlsson, Fredrik; Malmsten, Martin

2001-04-01

The effect of chemical degradation of two diblock copolymers of poly(ethylene oxide) (E) and poly(lactide) (L), E(39)L(5) and E(39)L(20), on their adsorption at silica and methylated silica was investigated with in situ ellipsometry. Steric stablization of polystyrene dispersions was investigated in relation to degradation. Hydrolysis of the poly(lactide) block of the copolymers was followed at different temperatures and pH by using HPLC to measure the occurrence of lactic acid in solution. The block copolymers were quite stable in pH-unadjusted solution at low temperature, whereas degradation was facilitated by increasing temperature or lowering of the pH. Lower degradation rates of E(39)L(20) where observed at low temperature in comparison with those of E(39)L(5), whereas the degradation rates of the copolymers were quantitatively similar at high temperature. The adsorption of the copolymers at methylated silica substrates decreased with increasing degree of degradation due to the reduction in the ability of hydrophobic block to anchor the copolymer layer at the surface. At silica the adsorption initially increased with increasing degradation, particularly for E(39)L(20) due to deposition of aggregates onto the surface. After extensive degradation the adsorption of the copolymers at both silica and methylated silica resembled that of the corresponding poly(ethylene oxide) homopolymer. Overall, it was found that the eventual reduction in adsorption occurred at a lower degree of degradation for E(39)L(5) than for E(39)L(20). Mean-field calculations showed a reduced anchoring for the block copolymers with decreasing poly(lactide) block length at hydrophobic surfaces. In accordance with this finding, it was observed that polystyrene dispersions were stabilized by E(39)L(20) or E(39)L(5) in a way that depended on both the lactide block length and the degree of degradation. Upon degradation of the hydrophobic block, stabilization of the polystyrene dispersions was maintained initially, but eventually degradation resulted in destabilization. The average residual copolymer concentration required for stabilization of the polystyrene dispersions was much higher than the corresponding concentration of intact copolymer required for stabilization. Copyright 2001 Academic Press.

Positively charged and bipolar layered poly(ether imide) nanofiltration membranes for water softening applications

NASA Astrophysics Data System (ADS)

Gassara, S.; Abdelkafi, A.; Quémener, D.; Amar, R. Ben; Deratani, A.

2015-07-01

Poly(ether imide) (PEI) ultrafiltration membranes were chemically modified with branched poly(ethyleneimine) to obtain nanofiltration (NF) membrane Cat PEI with a positive charge in the pH range below 9. An oppositely charged polyelectrolyte layer was deposited on the resulting membrane surface by using sodium polystyrene sulfonate (PSSNa) and sodium polyvinyl sulfonate (PVSNa) to prepare a bipolar layered membrane NF Cat PEI_PSS and Cat PEI_PVS having a negatively charged surface and positively charged pores. Cat PEI exhibited good performance to remove multivalent cations (more than 90% of Ca2+) from single salt solutions except in presence of sulfate ions. Adding an anionic polyelectrolyte layer onto the positively charged surface resulted in a significant enhancement of rejection performance even in presence of sulfate anions. Application of the prepared membranes in water softening of natural complex mixtures was successful for the different studied membranes and a large decrease of hardness was obtained. Moreover, Cat PEI_PSS showed a good selectivity for nitrate removal. Fouling experiments were carried out with bovine serum albumin, as model protein foulant. Cat PEI_PSS showed much better fouling resistance than Cat PEI with a quantitative flux recovery ratio.

Directed self-assembly of high-chi block copolymer for nano fabrication of bit patterned media via solvent annealing

NASA Astrophysics Data System (ADS)

Xiong, Shisheng; Chapuis, Yves-Andre; Wan, Lei; Gao, He; Li, Xiao; Ruiz, Ricardo; Nealey, Paul F.

2016-10-01

We report the formation of nanoimprint master templates that can be used for the fabrication of bit patterned media (BPM). The template was formed by directed self-assembly, with solvent annealing, of a symmetric ABA triblock copolymer to form perpendicularly oriented lamellae on chemical patterns. We used a high-χ block copolymer, poly(2-vinyl pyridine)-block-polystyrene-block-poly(2-vinyl pyridine) to achieve smaller feature sizes than are possible with polystyrene-block-poly(methyl methacrylate). The work shows that triblock copolymers can provide a large processing window in terms of pitch commensurability. Using block-selective infiltration (atomic layer deposition with sequential long soaking/purge cycles), an alumina composite with high etch resistance was specifically incorporated into the polar and hydrophilic P2VP domains. Subsequently, the surface pattern was successfully transferred into underlying Si substrates by etching with a fluorine-containing plasma to create a nanoimprint master. The line/space pattern of the nanoimprint master met the BPM fabrication requirement of defectivity <10-3. For demonstration purposes, the nanoimprint master was used to imprint a replica pattern of photoresist on a quartz wafer.

Poly-SiGe MEMS actuators for adaptive optics

NASA Astrophysics Data System (ADS)

Lin, Blake C.; King, Tsu-Jae; Muller, Richard S.

2006-01-01

Many adaptive optics (AO) applications require mirror arrays with hundreds to thousands of segments, necessitating a CMOS-compatible MEMS process to integrate the mirrors with their driving electronics. This paper proposes a MEMS actuator that is fabricated using low-temperature polycrystalline silicon-germanium (poly-SiGe) surface-micromaching technology (total thermal budget is 6 hours at or below 425°C). The MEMS actuator consists of three flexures and a hexagonal platform, on which a micromirror is to be assembled. The flexures are made of single-layer poly-SiGe with stress gradient across thickness of the film, making them bend out-of-plane after sacrificial-layer release to create a large nominal gap. The platform, on the other hand, has an additional stress-balancing SiGe layer deposited on top, making the dual-layer stack stay flat after release. Using this process, we have successfully fabricated the MEMS actuator which is lifted 14.6 μm out-of-plane by 290-μm-long flexures. The 2-μm-thick hexagonal mirror-platform exhibits a strain gradient of -5.5×10 -5 μm -1 (equivalent to 18 mm radius-of-curvature), which would be further reduced once the micromirror is assembled.

Intravenous injections of soluble drag-reducing polymers reduce foreign body reaction to implants.

PubMed

Marascalco, Philip J; Blair, Harry C; Nieponice, Alejandro; Robinson, Lisa J; Kameneva, Marina V

2009-01-01

We tested whether soluble viscoelastic drag-reducing polymers (DRPs), which modify blood flow in the macro- and microcirculation, affect host response to implanted biomaterials and control biodegradation and tissue ingrowth processes. Porous poly(L-lactate) (PLLA) implants, which are naturally hydrolyzed by foreign body giant cells, were used to evaluate differences in host response. Intravenous DRPs, high-molecular weight poly(ethylene oxide) (PEO) or poly(mannose) (PMNN), were given biweekly at 0.3-0.4 nM in saline (equivalent volumes of saline in controls) to rats with subcutaneous PLLA implants. After 7 weeks, there was no difference in weight gain or behavior between control and DRP-injected groups. Implanted PLLA scaffolds in controls were almost totally degraded and replaced by giant cell granulomas. On the contrary, PEO- or PMNN-treated animals retained a significant part of the implanted scaffold (p < 0.0001 vs. controls). The foreign body reaction was markedly decreased, and there was an increase in well-oriented collagen deposition within the implanted scaffold area in the animals treated with DRPs. The DRP-mediated effects observed in this study potentially reflect alteration in inflammatory events in response to implanted bioengineered materials, and, thus, warrant further investigation.

Effect of O/W process parameters on Crataegus azarolus L nanocapsule properties.

PubMed

Esmaeili, Akbar; Rahnamoun, Soraya; Sharifnia, Fariba

2013-05-29

Nanocapsules have many applications in the drug, cosmetic, fragrance, and food industries. In this study, Crataegus azarolus L. nanocapsules were prepared by a modified emulsion diffusion technique. In this technique a shell was first made from the polyester triblock copolymer poly(ethylene glycol)-poly(butylene adipate)-poly(ethylene glycol) (PEG-PBA-PEG) and then olive oil was set as the core of the nanocapsule by a method known as the polymer deposition solvent evaporation method. Varying amounts of C. azarolus extract, polymer, and olive oil were mixed in acetone and then added to water on a shaker. Finally, the acetone was removed by vacuuming. The size of the prepared nanocapsules were measured with a particle size analysis report (PSAR) and identified by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Our experiments showed that the size of the nanocapsules depends on the preparation conditions, i.e., the ratio of polymer to oil and concentrations of polymer and plant extract. A ratio of 1:0.25 polymer to oil was shown to be more suitable for the formation of smaller nanocapsules of C. azarolus.

Effect of O/W process parameters on Crataegus azarolus L nanocapsule properties

PubMed Central

2013-01-01

Background Nanocapsules have many applications in the drug, cosmetic, fragrance, and food industries. In this study, Crataegus azarolus L. nanocapsules were prepared by a modified emulsion diffusion technique. Methods In this technique a shell was first made from the polyester triblock copolymer poly(ethylene glycol)-poly(butylene adipate)-poly(ethylene glycol) (PEG-PBA-PEG) and then olive oil was set as the core of the nanocapsule by a method known as the polymer deposition solvent evaporation method. Varying amounts of C. azarolus extract, polymer, and olive oil were mixed in acetone and then added to water on a shaker. Finally, the acetone was removed by vacuuming. Results The size of the prepared nanocapsules were measured with a particle size analysis report (PSAR) and identified by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and nuclear magnetic resonance (NMR). Conclusions Our experiments showed that the size of the nanocapsules depends on the preparation conditions, i.e., the ratio of polymer to oil and concentrations of polymer and plant extract. A ratio of 1:0.25 polymer to oil was shown to be more suitable for the formation of smaller nanocapsules of C. azarolus. PMID:23718829

PolySUMOylation by Siz2 and Mms21 triggers relocation of DNA breaks to nuclear pores through the Slx5/Slx8 STUbL

PubMed Central

Horigome, Chihiro; Bustard, Denise E.; Marcomini, Isabella; Delgoshaie, Neda; Tsai-Pflugfelder, Monika; Cobb, Jennifer A.; Gasser, Susan M.

2016-01-01

High-resolution imaging shows that persistent DNA damage in budding yeast localizes in distinct perinuclear foci for repair. The signals that trigger DNA double-strand break (DSB) relocation or determine their destination are unknown. We show here that DSB relocation to the nuclear envelope depends on SUMOylation mediated by the E3 ligases Siz2 and Mms21. In G1, a polySUMOylation signal deposited coordinately by Mms21 and Siz2 recruits the SUMO targeted ubiquitin ligase Slx5/Slx8 to persistent breaks. Both Slx5 and Slx8 are necessary for damage relocation to nuclear pores. When targeted to an undamaged locus, however, Slx5 alone can mediate relocation in G1-phase cells, bypassing the requirement for polySUMOylation. In contrast, in S-phase cells, monoSUMOylation mediated by the Rtt107-stabilized SMC5/6–Mms21 E3 complex drives DSBs to the SUN domain protein Mps3 in a manner independent of Slx5. Slx5/Slx8 and binding to pores favor repair by ectopic break-induced replication and imprecise end-joining. PMID:27056668

Hot-Carrier Immunity of Polycrystalline Silicon Thin Film Transistors Using Silicon Oxynitride Gate Dielectric Formed with Plasma-Enhanced Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Kunii, Masafumi

2009-11-01

An analysis is presented of the hot-carrier degradation in a polycrystalline silicon (poly-Si) thin film transistor (TFT) with a silicon oxynitride gate dielectric formed with plasma-enhanced chemical vapor deposition. An introduction of silicon oxynitride into a gate dielectric significantly improves hot-carrier immunity even under the severe stressing mode of drain avalanche hot carriers. To compensate the initial negative shift of threshold voltage for TFTs with a silicon oxynitride gate dielectric, high-pressure water vapor annealing (HWA) is applied. A comparison of TFTs with and without HWA reveals that the improvement in hot-carrier immunity is mainly attributed to the introduction of Si≡N bonds into a gate dielectric.

Fabrication and Characterization of Thermoresponsive Films Deposited by an RF Plasma Reactor

PubMed Central

Lucero, Adrianne E.; Reed, Jamie A.; Wu, Xiaomei; Canavan, Heather E.

2014-01-01

Summary Poly(N-isopropyl acrylamide) (pNIPAM) undergoes a sharp property change in response to a moderate thermal stimulus at physiological temperatures. In this work, we constructed a radio frequency (RF) plasma reactor for the plasma polymerization of pNIPAM. RF deposition is a method that coats surfaces of any geometry producing surfaces that are sterile and uniform, making this technique useful for forming biocompatible films. The films generated are characterized using X-ray photoelectron spectroscopy (XPS), contact angles, cell culture, and interferometry. We find that a plasma with a decreasing series of power settings (i.e., from 100W to 1W) at a pressure of 140 millitorr yields the most favorable results. PMID:24634643

Transparent photostable ZnO nonvolatile memory transistor with ferroelectric polymer and sputter-deposited oxide gate

NASA Astrophysics Data System (ADS)

Park, C. H.; Im, Seongil; Yun, Jungheum; Lee, Gun Hwan; Lee, Byoung H.; Sung, Myung M.

2009-11-01

We report on the fabrication of transparent top-gate ZnO nonvolatile memory thin-film transistors (NVM-TFTs) with 200 nm thick poly(vinylidene fluoride/trifluoroethylene) ferroelectric layer; semitransparent 10 nm thin AgOx and transparent 130 nm thick indium-zinc oxide (IZO) were deposited on the ferroelectric polymer as gate electrode by rf sputtering. Our semitransparent NVM-TFT with AgOx gate operates under low voltage write-erase (WR-ER) pulse of ±20 V, but shows some degradation in retention property. In contrast, our transparent IZO-gated device displays very good retention properties but requires anomalously higher pulse of ±70 V for WR and ER states. Both devices stably operated under visible illuminations.

In situ X-ray study of the structural evolution of gold nano-domains by spray deposition on thin conductive P3HT films.

PubMed

Al-Hussein, M; Schindler, M; Ruderer, M A; Perlich, J; Schwartzkopf, M; Herzog, G; Heidmann, B; Buffet, A; Roth, S V; Müller-Buschbaum, P

2013-02-26

Gold (Au) nanoparticles are deposited from aqueous solution onto one of the most used conductive polymers, namely poly(3-hexylthiophene) (P3HT), using airbrush deposition. We report on the structure formation and packing of the Au nanoparticles after a 5 s spray cycle. In situ grazing incidence small-angle X-ray scattering (GISAXS) measurements with 20 ms time resolution allow a real-time observation of the emergence and evolution of the microstructure during a spray cycle and subsequent solvent evaporation. The results reveal multistage nanoscale ordering of the Au nanoparticles during the spray cycle. Further ex situ atomic force microscopy measurements of the sprayed films showed the formation of Au monolayer islands on top of the polymer film. Our study suggests that the solvent-substrate interaction as well as solvent evaporation kinetics are important factors that need to be taken into consideration in order to grow a compact uniform monolayer film for the fabrication of ultrathin films using airbrush deposition.

Enhanced Performance of Gate-First p-Channel Metal-Insulator-Semiconductor Field-Effect Transistors with Polycrystalline Silicon/TiN/HfSiON Stacks Fabricated by Physical Vapor Deposition Based In situ Method

NASA Astrophysics Data System (ADS)

Kitano, Naomu; Horie, Shinya; Arimura, Hiroaki; Kawahara, Takaaki; Sakashita, Shinsuke; Nishida, Yukio; Yugami, Jiro; Minami, Takashi; Kosuda, Motomu; Hosoi, Takuji; Shimura, Takayoshi; Watanabe, Heiji

2007-12-01

We demonstrated the use of an in situ metal/high-k fabrication method for improving the performance of metal-insulator-semiconductor field-effect transistors (MISFETs). Gate-first pMISFETs with polycrystalline silicon (poly-Si)/TiN/HfSiON stacks were fabricated by techniques based on low-damage physical vapor deposition, in which high-quality HfSiON dielectrics were formed by the interface reaction between an ultrathin metal-Hf layer (0.5 nm thick) and a SiO2 underlayer, and TiN electrodes were continuously deposited on the gate dielectrics without exposure to air. Gate-first pMISFETs with high carrier mobility and a low threshold voltage (Vth) were realized by reducing the carbon impurity in the gate stacks and improving the Vth stability against thermal treatment. As a result, we obtained superior current drivability (Ion = 350 μA/μm at Ioff = 200 pA/μm), which corresponds to a 13% improvement over that of conventional chemical vapor deposition-based metal/high-k devices.

The enigma of aluminum deposition in bone tissue from a patient with chronic kidney disease: a case report.

PubMed

Meira, Rodrigo Dias de; Carbonara, Cinthia Esbrile Moraes; Quadros, Kélcia Rosana da Silva; Santos, Carolina Urbini Dos; Schincariol, Patrícia; Pêssoa, Gustavo de Souza; Arruda, Marco Aurélio Zezzi; Jorgetti, Vanda; Oliveira, Rodrigo Bueno de

2018-06-04

About four decades ago, the relationship between dialysis-dementia and aluminum (Al) began to be established. The restriction of drugs containing Al and improvements on water quality used for dialysis resulted in the clinical disappearance of Al intoxication. However, high prevalence of Al deposition in bone tissue from Brazilian dialysis patients is still being detected. Through the case report of a patient on hemodialysis (HD) for one year, presenting significant Al deposition in bone tissue, we speculated if this problem is not being underestimated. We used extensive investigation to identify potential sources of Al exposure with a careful review of medication history and water quality controls. Al concentration was measured by different methods, including mass spectrometry, in poly-electrolyte concentrate solutions and solution for peritoneal dialysis, in an attempt to elucidate the possible sources of contamination. The objective of this case report is to alert the medical community about a potential high prevalence of Al deposition in bone tissue and to discuss the possible sources of contamination in patients with chronic kidney disease (CKD).

Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas-liquid membrane contactor system.

PubMed

Jin, Pengrui; Huang, Chuan; Li, Jiaxiang; Shen, Yadong; Wang, Liao

2017-11-01

The wetting of hollow fibre membranes decreases the performance of the liquid-gas membrane contactor for CO 2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid-gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO 2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO 2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO 2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre-sized roughness on the surface of the PVDF membrane, which was achieved with a SiO 2 concentration of 4.44 mg ml -1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155 ± 3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO 2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed that the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid-gas membrane absorption.

The Itajaí foreland basin: a tectono-sedimentary record of the Ediacaran period, Southern Brazil

NASA Astrophysics Data System (ADS)

Basei, M. A. S.; Drukas, C. O.; Nutman, A. P.; Wemmer, K.; Dunyi, L.; Santos, P. R.; Passarelli, C. R.; Campos Neto, M. C.; Siga, O.; Osako, L.

2011-04-01

The Itajaí Basin located in the southern border of the Luís Alves Microplate is considered as a peripheral foreland basin related to the Dom Feliciano Belt. It presents an excellent record of the Ediacaran period, and its upper parts display the best Brazilian example of Precambrian turbiditic deposits. The basal succession of Itajaí Group is represented by sandstones and conglomerates (Baú Formation) deposited in alluvial and deltaic-fan systems. The marine upper sequences correspond to the Ribeirão Carvalho (channelized and non-channelized proximal silty-argillaceous rhythmic turbidites), Ribeirão Neisse (arkosic sandstones and siltites), and Ribeirão do Bode (distal silty turbidites) formations. The Apiúna Formation felsic volcanic rocks crosscut the sedimentary succession. The Cambrian Subida leucosyenogranite represents the last felsic magmatic activity to affect the Itajaí Basin. The Brusque Group and the Florianópolis Batholith are proposed as source areas for the sediments of the upper sequence. For the lower continental units the source areas are the Santa Catarina, São Miguel and Camboriú complexes. The lack of any oceanic crust in the Itajaí Basin suggests that the marine units were deposited in a restricted, internal sea. The sedimentation started around 600 Ma and ended before 560 Ma as indicated by the emplacement of rhyolitic domes. The Itajaí Basin is temporally and tectonically correlated with the Camaquã Basin in Rio Grande do Sul and the Arroyo del Soldado/Piriápolis Basin in Uruguay. It also has several tectono-sedimentary characteristics in common with the African-equivalent Nama Basin.

Polyelectrolyte multi-layers assembly of SiCHA nanopowders and collagen type I on aminolysed PLA films to enhance cell-material interactions.

PubMed

Baba Ismail, Yanny Marliana; Ferreira, Ana Marina; Bretcanu, Oana; Dalgarno, Kenneth; El Haj, Alicia J

2017-11-01

This paper presents a new approach in assembling bone extracellular matrix components onto PLA films, and investigates the most favourable environment which can be created using the technique for cell-material interactions. Poly (lactic acid) (PLA) films were chemically modified by covalently binding the poly(ethylene imine) (PEI) as to prepare the substrate for immobilization of polyelectrolyte multilayers (PEMs) coating. Negatively charged polyelectrolyte consists of well-dispersed silicon-carbonated hydroxyapatite (SiCHA) nanopowders in hyaluronic acid (Hya) was deposited onto the modified PLA films followed by SiCHA in collagen type I as the positively charged polyelectrolyte. The outermost layer was finally cross-linked by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrocholoride and N-hydroxysulfosuccinimide sodium salt (EDC/NHS) solutions. The physicochemical features of the coated PLA films were monitored via X-ray Photoelectron Spectroscopy (XPS) and Atomic Force Microscope (AFM). The amounts of calcium and collagen deposited on the surface were qualitatively and quantitatively determined. The surface characterizations suggested that 5-BL has the optimum surface roughness and highest amounts of calcium and collagen depositions among tested films. In vitro human mesenchymal stem cells (hMSCs) cultured on the coated PLA films confirmed that the coating materials greatly improved cell attachment and survival compared to unmodified PLA films. The cell viability, cell proliferation and Alkaline Phosphatase (ALP) expression on 5-BL were found to be the most favourable of the tested films. Hence, this newly developed coating materials assembly could contribute to the improvement of the bioactivity of polymeric materials and structures aimed to bone tissue engineering applications. Copyright © 2017 Elsevier B.V. All rights reserved.

Pore size and LbL chitosan coating influence mesenchymal stem cell in vitro fibrosis and biomineralization in 3D porous poly(epsilon-caprolactone) scaffolds.

PubMed

Mehr, Nima Ghavidel; Li, Xian; Chen, Gaoping; Favis, Basil D; Hoemann, Caroline D

2015-07-01

Poly(epsilon-caprolactone) (PCL) is a hydrophobic bioplastic under development for bone tissue engineering applications. Limited information is available on the role of internal geometry and cell-surface attachment on osseous integration potential. We tested the hypothesis that human bone marrow mesenchymal stem cells (MSCs) deposit more mineral inside porous 3D PCL scaffolds with fully interconnected 84 or 141 µm pores, when the surfaces are coated with chitosan via Layer-by-Layer (LbL)-deposited polyelectrolytes. Freshly trypsinized MSCs were seeded on PCL 3D cylinders using a novel static cold seeding method in 2% serum to optimally populate all depths of the scaffold discs, followed by 10 days of culture in proliferation medium and 21 additional days in osteogenic medium. MSCs were observed by SEM and histology to spread faster and to proliferate more on chitosan-coated pore surfaces. Most pores, with or without chitosan, became filled by collagen networks sparsely populated with fibroblast-like cells. After 21 days of culture in osteogenic medium, sporadic matrix mineralization was detected histologically and by micro-CT in highly cellular surface layers that enveloped all scaffolds and in cell aggregates in 141 µm pores near the edges. LbL-chitosan promoted punctate mineral deposition on the surfaces of 84 µm pores (p < 0.05 vs. PCL-only) but not the 141 µm pores. This study revealed that LbL-chitosan coatings are sufficient to promote MSC attachment to PCL but only enhance mineral formation in 84 µm pores, suggesting a potential inhibitory role for MSC-derived fibroblasts in osteoblast terminal differentiation. © 2014 Wiley Periodicals, Inc.

Surface modification of poly(vinylidene fluoride) hollow fibre membranes for biogas purification in a gas–liquid membrane contactor system

PubMed Central

Huang, Chuan; Li, Jiaxiang; Shen, Yadong; Wang, Liao

2017-01-01

The wetting of hollow fibre membranes decreases the performance of the liquid–gas membrane contactor for CO2 capture in biogas upgrading. To solve this problem, in this work, a poly(vinylidene fluoride) (PVDF) hollow fibre membrane for a liquid–gas membrane contactor was coated with a superhydrophobic layer composed of a combination of hydrophobic SiO2 nanoparticles and polydimethylsiloxane (PDMS) by the method of spray deposition. A rough layer of SiO2 deposited on the PVDF membrane resulted in an enhanced surface hydrophobicity. The surface structure of the pristine PVDF significantly affected the homogeneity of the generated SiO2 layer. A uniform surface coating on the PVDF upper layer resulted from the presence of micrometre and nanometre-sized roughness on the surface of the PVDF membrane, which was achieved with a SiO2 concentration of 4.44 mg ml−1 (0.2 g/45 ml) in the coating solution. As a result, the water contact angle of the modified surface was recorded as 155 ± 3°, which is higher than that of the pristine surface. The high contact angle is advantageous for reducing the wetting of the membrane. Additional mass transfer resistance was introduced by the superhydrophobic layer. In addition, continuous CO2 absorption tests were carried out in original and modified PVDF hollow fibre membrane contactors, using monoethanolamine (MEA) solution as the absorbent. A long-term stability test revealed that the modified PVDF hollow fibre membrane contactor was able to outperform the original membrane contactor and demonstrated outstanding long-term stability, suggesting that spray deposition is a promising approach to obtain superhydrophobic PVDF membranes for liquid–gas membrane absorption. PMID:29291117

Formation of High-Quality μm-Order-Thick Poly-Si Films on Glass-Substrates by Flash Lamp Annealing

NASA Astrophysics Data System (ADS)

Ohdaira, Keisuke

Flash lamp annealing (FLA), millisecond-order discharge from Xe lamps, can form a few μm-thick polycrystalline Si (poly-Si) films by crystallizing precursor amorphous Si (a-Si) films prepared on low-cost substrates without serious thermal damage onto the whole glass substrates, thanks to its proper annealing duration. The FLA of a-Si films can induce lateral explosive crystallization (EC), self-catalytic crystallization driven by the release of latent heat. Periodic structures with a spacing of ˜1 μm are spontaneously left behind on and inside flash-lamp-crystallized (FLC) poly-Si films formed, when chemical-vapor-deposited (CVD) or sputtered a-Si films are used as precursor films. These microstructures result from the alternative emergence of two types of crystallization with different mechanisms during FLA: one is governed only by solid-phase nucleation (SPN) and the other includes SPN and partial liquid-phase epitaxy (LPE), resulting in the formation of grains with sizes of 10-500 nm. This rapid lateral crystallization leads to the complete preservation of abrupt dopant profiles, which is favorable for device fabrication. This particular crystallization also results in the suppression of hydrogen desorption during FLA, which realizes the formation of poly-Si films with hydrogen atoms on the order of 1021/cm3. Hydrogen atoms in poly-Si films probably act to reduce defect density, which can be on the order of 1016/cm3 after conventional furnace annealing in inert gas atmosphere. These features are suitable for the realization of high-efficiency thin-film poly-Si solar cells. Furthermore, a different type of EC can occur when using electron-beam-(EB-) evaporated a-Si films as precursor films. All the grains in the FLC poly-Si films formed stretch along lateral crystallization direction, and the length of grains is typically more than 10 μm. Based on the results of multi-pulse FLA technique, the velocity of EC is estimated to be ˜14 m/s, which corresponds to the speed of LPE at around the melting point of a-Si, indicating that this EC occurs completely in liquid phase. This approach to form large-grain poly-Si films can also contribute to realizing high-performance solar cells.

Apatite mineralization in elasmobranch skeletons via a polyphosphate intermediate

NASA Astrophysics Data System (ADS)

Omelon, Sidney; Lacroix, Nicolas; Lildhar, Levannia; Variola, Fabio; Dean, Mason

2014-05-01

All vertebrate skeletons are stiffened with apatite, a calcium phosphate mineral. Control of apatite mineralization is essential to the growth and repair of the biology of these skeletons, ensuring that apatite is deposited in the correct tissue location at the desired time. The mechanism of this biochemical control remains debated, but must involve increasing the localized apatite saturation state. It was theorized in 1923 that alkaline phosphatase (ALP) activity provides this control mechanism by increasing the inorganic phosphate (Pi) concentration via dephosphorylation of phosphorylated molecules. The ALP substrate for biological apatite is not known. We propose that polyphosphates (polyPs) produced by mitochondria may be the substrate for biological apatite formation by ALP activity. PolyPs (PO3-)n, also known as condensed phosphates, represent a concentrated, bioavailable Pi-storage strategy. Mitochondria import Pi and synthesize phosphate polymers through an unknown biochemical mechanism. When chelated with calcium and/or other cations, the effective P-concentration of these neutrally charged, amorphous, polyP species can be very high (~ 0.5 M), without inducing phosphate mineral crystallization. This P-concentration in the low Pi-concentration biological environment offers a method of concentrating P well above an apatite supersaturation required for nucleation. Bone is the most studied mineralized skeletal tissue. However, locating and analyzing active mineralizing areas is challenging. We studied calcified cartilage skeletons of elasmobranch fishes (sharks, stingrays and relatives) to analyse the phosphate chemistry in this continually mineralizing skeleton. Although the majority of the elasmobranch skeleton is unmineralized cartilage, it is wrapped in an outer layer of mineralized tissue comprised of small tiles called tesserae. These calcified tesserae continually grow through the formation of new mineral on their borders. Co-localization of ALP and polyPs were identified at the mineralizing tessera borders using Raman spectroscopy, fluorescence microscopy and histological methods. Application of exogenous ALP to skeletal tissue cross-sections resulted in polyP disappearance, and Pi production. It is proposed that elasmobranch skeletal cells produce polyP-containing granules as a concentrated P-source, while ALP activity controls when and where Pi is cleaved from polyP, increasing the apatite supersaturation to nucleate apatite minerals in the skeleton. These data support not only interaction of polyP and ALP as a cell-mediated apatite mineralization control mechanism, but also suggest that this mechanism arose millions of years ago and is common to both bony and cartilaginous skeletal systems.

Polyelectrolyte and carbon nanotube multilayers made from ionic liquid solutions

NASA Astrophysics Data System (ADS)

Nakashima, Takuya; Zhu, Jian; Qin, Ming; Ho, Szushen; Kotov, Nicholas A.

2010-10-01

The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods.The inevitable contact of substrates with water during the traditional practice of layer-by-layer assembly (LBL) creates problems for multiple potential applications of LBL films in electronics. To resolve this issue, we demonstrate here the possibility of a LBL process using ionic liquids (ILs), which potentially eliminates corrosion and hydration processes related to aqueous media and opens additional possibilities in structural control of LBL films. ILs are also considered to be one of the best ``green'' processing solvents, and hence, are advantageous in respect to traditional organic solvents. Poly(ethyleneimine) (PEI) and poly(sodium styrenesulfonate) (PSS) were dispersed in a hydrophilic IL and successfully deposited in the LBL fashion. To produce electroactive thin films with significance to electronics, a similar process was realized for PSS-modified single-walled carbon nanotubes (SWNT-PSS) and poly(vinyl alcohol) (PVA). Characterization of the coating using standard spectroscopy and microscopy techniques typical of the multilayer field indicated that there are both similarities and differences in the structure and properties of LBL films build from ILs and aqueous solutions. The films exhibited electrical conductivity of 102 S m-1 with transparency as high as 98% for visible light, which is comparable to similar parameters for many carbon nanotube and graphene films prepared by both aqueous LBL and other methods. Electronic supplementary information (ESI) available: Aggregation of PEI and PSS in [EMIm][EtSO4], detailed FTIR data, water-contact angle for (PEI/PSS)10 multilayers, and XPS survey spectra. See DOI: 10.1039/b9nr00333a

Stimulated emission within the exciplex band by plasmonic-nanostructured polymeric heterojunctions.

PubMed

Zhang, Xinping; Li, Hongwei; Wang, Yimeng; Liu, Feifei

2015-03-19

Organic heterojunctions have been extensively employed in the design of light-emitting diodes, photovoltaic devices, and thin-film field-effect transistors, which can be achieved by constructing a bilayer or a multi-layered thin-film deposition, or by blending two or more organic semiconductors with different charge-transport performances. Charge transfer excited states or exciplex may form on the heterointerfaces. Efficient light-emitting diodes have been demonstrated using exciplex emission. However, lasing or stimulated emission processes have not been observed with exciplex formation at organic heterojunctions. In this work, we demonstrate strong coherent interaction between photons and exciplex formation in the blends of poly-9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-l,4-phenylenediamine (PFB) and poly-9,9'-dioctylfluorene-co-benzothiadiazole (F8BT), leading to transient stimulated exciplex emission. The responsible mechanisms involve plasmonic local-field enhancement and plasmonic feedback in a three-dimensional gold-nanoparticle matrix.

Three-Dimensional Printing with Biomass-Derived PEF for Carbon-Neutral Manufacturing.

PubMed

Kucherov, Fedor A; Gordeev, Evgeny G; Kashin, Alexey S; Ananikov, Valentine P

2017-12-11

Biomass-derived poly(ethylene-2,5-furandicarboxylate) (PEF) has been used for fused deposition modeling (FDM) 3D printing. A complete cycle from cellulose to the printed object has been performed. The printed PEF objects created in the present study show higher chemical resistance than objects printed with commonly available materials (acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), glycol-modified poly(ethylene terephthalate) (PETG)). The studied PEF polymer has shown key advantages for 3D printing: optimal adhesion, thermoplasticity, lack of delamination and low heat shrinkage. The high thermal stability of PEF and relatively low temperature that is necessary for extrusion are optimal for recycling printed objects and minimizing waste. Several successive cycles of 3D printing and recycling were successfully shown. The suggested approach for extending additive manufacturing to carbon-neutral materials opens a new direction in the field of sustainable development. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improving Fire Resistance of Cotton Fabric through Layer-by-Layer Assembled Graphene Multilayer Nanocoating

NASA Astrophysics Data System (ADS)

Jang, Wonjun; Chung, Il Jun; Kim, Junwoo; Seo, Seongmin; Park, Yong Tae; Choi, Kyungwho

2018-05-01

In this study, thin films containing poly(vinyl alcohol) (PVA) and graphene nanoplatelets (GNPs), stabilized with poly(4-styrene-sulfonic acid) (PSS), were assembled by a simple and cost-effective layer-by-layer (LbL) technique in order to introduce the anti-flammability to cotton. These antiflammable layers were characterized by using UV-vis spectrometry and quartz crystal microbalance as a function of the number of bilayers deposited. Scanning electron microscopy was used to visualize the morphology of the thin film coatings on the cotton fabric. The graphene-polymer thin films introduced anti-flammable properties through thermally stable carbonaceous layers at a high temperature. The thermal stability and flame retardant property of graphene-coated cotton was demonstrated by thermogravimetric analysis, cone calorimetry, and vertical flame test. The results indicate that LbL-assembled graphene-polymer thin films can be applied largely in the field of flame retardant.

Cell adhesion and proliferation on poly(tetrafluoroethylene) with plasma-metal and plasma-metal-carbon interfaces

NASA Astrophysics Data System (ADS)

Reznickova, Alena; Kvitek, Ondrej; Kolarova, Katerina; Smejkalova, Zuzana; Svorcik, Vaclav

2017-06-01

The aim of this article is to investigate the effect of the interface between plasma activated, gold and carbon coated poly(tetrafluoroethylene) (PTFE) on in vitro adhesion and spreading of mouse fibroblasts (L929). Surface properties of pristine and modified PTFE were studied by several experimental techniques. The thickness of a deposited gold film is an increasing function of the sputtering time, conversely thickness of carbon layer decreases with increasing distance between carbon source and the substrate. Because all the used surface modification techniques take place in inert Ar plasma, oxidized degradation products are formed on the PTFE surface, which affects wettability of the polymer surface. Cytocompatibility tests indicate that on samples with Au/C interface, the cells accumulate on the part of sample with evaporated carbon. Number of L929 cells proliferated on the studied samples is comparable to tissue culture polystyrene standard.

Femtosecond laser surface texturing of 3D poly-ε-caprolactone matrices for bone tissue engineering applications

NASA Astrophysics Data System (ADS)

Daskalova, A.; Bliznakova, I.; Zhelyazkova, A.; Ostrowska, B.; Trifonov, A.; Buchvarov, I.; Avramov, L.; Husinsky, W.

2018-03-01

Fibrous 3D matrices were fabricated from poly-ɛ-caprolactone (PCL) by fused deposition modeling. Femtosecond laser irradiation was then used to demonstrate the possibility to affect the porosity of the 3D PCL fiber meshes. The surface characteristics were analyzed by scanning electron microscopy (SEM) and confocal microscopy. The interrelationship was examined between the laser processing parameters (number of pulses, pulse energy applied) and the response of the biomaterial. The formation was demonstrated of well-defined micropores, while the original fiber structure was retained. The study of cells cultivation on the laser-modified scaffolds showed good adhesion compared to a non-modified scaffold. The results obtained showed that femtosecond laser processing can be used as an alternative non-contact tool in enhancing the porosity of artificial constructs, thus influencing the cell adhesion into fibrous meshes.

Preparation of conductive gold nanowires in confined environment of gold-filled polymer nanotubes.

PubMed

Mitschang, Fabian; Langner, Markus; Vieker, Henning; Beyer, André; Greiner, Andreas

2015-02-01

Continuous conductive gold nanofibers are prepared via the "tubes by fiber templates" process. First, poly(l-lactide) (PLLA)-stabilized gold nanoparticles (AuNP) with over 60 wt% gold are synthesized and characterized, including gel permeation chromatography coupled with a diode array detector. Subsequent electrospinning of these AuNP with template PLLA results in composite nanofibers featuring a high gold content of 57 wt%. Highly homogeneous gold nanowires are obtained after chemical vapor deposition of 345 nm of poly(p-xylylene) (PPX) onto the composite fibers followed by pyrolysis of the polymers at 1050 °C. The corresponding heat-induced transition from continuous gold-loaded polymer tubes to smooth gold nanofibers is studied by transmission electron microscopy and helium ion microscopy using both secondary electrons and Rutherford backscattered ions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

NASA Astrophysics Data System (ADS)

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

2018-06-01

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

Electrical properties of multilayers from low- and high-molecular-weight polyelectrolytes.

PubMed

Radeva, Tsetska; Milkova, Viktoria; Petkanchin, Ivana

2004-11-15

The formation of stable multilayer films by using as constituents sodium poly(4-styrene sulfonate) (PSS) and poly(4-vinyl pyridine) (PVP) was studied by electrooptics. A strong increase in basicity of the pyridine rings in the electrical field of the oppositely charged PSS chains was suggested to be the driving force for multilayer film formation. A linear increase in the film thickness was registered after deposition of the first three layers, with no dependence on the polyelectrolyte molecular weight. The electrooptical effect was found to increase with increasing area of each next layer, but depended on the molecular weights of both polymers. Polarization of "condensed" counterions along the chains of the last-adsorbed layer was suggested to explain this dependence. Following the counterion dynamics, we come to the conclusion that the electrical properties of the top layer govern the electrooptical behavior of the PSS/PVP film.

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

NASA Astrophysics Data System (ADS)

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

2018-05-01

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

Rear-Sided Passivation by SiNx:H Dielectric Layer for Improved Si/PEDOT:PSS Hybrid Heterojunction Solar Cells.

PubMed

Sun, Yiling; Gao, Pingqi; He, Jian; Zhou, Suqiong; Ying, Zhiqin; Yang, Xi; Xiang, Yong; Ye, Jichun

2016-12-01

Silicon/organic hybrid solar cells have recently attracted great attention because they combine the advantages of silicon (Si) and the organic cells. In this study, we added a patterned passivation layer of silicon nitride (SiNx:H) onto the rear surface of the Si substrate in a Si/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PSS) hybrid solar cell, enabling an improvement of 0.6 % in the power conversion efficiency (PCE). The addition of the SiNx:H layer boosted the open circuit voltage (V oc) from 0.523 to 0.557 V, suggesting the well-passivation property of the patterned SiNx:H thin layer that was created by plasma-enhanced chemical vapor deposition and lithography processes. The passivation properties that stemmed from front PSS, rear-SiNx:H, front PSS/rear-SiNx:H, etc. are thoroughly investigated, in consideration of the process-related variations.

Chemical Polymerization and Langmuir-Blodgett Techniques. 2. The Polymerization of Monolayers of 3-Substituted Pyrroles

DTIC Science & Technology

1993-09-12

the liquid -air interface could be monitored by changes in the surface area. Deposition of monolayers by Langmuir - Blodgett technique is possible and...polymerization product from the LB trough in chloroform solution. Figure 10 Langmuir - Blodgett transfer of poly (3-hexadecyl pyrrole) onto hydrophobized glass... Langmuir - Blodgett Techniques, 2: The Polymerization of Monolayers of 3-Substituted Pyrroles by W.M. Sigmund, C. Marestin, S. Keil, H. Zhou and R.S

Bacterial Sunscreen: Layer-by-Layer Deposition of UV-Absorbing Polymers on Whole-Cell Biosensors (POSTPRINT)

DTIC Science & Technology

2012-06-13

mycosporine - like amino acids that absorb in the UV range and can quench UV-induced intracellular free radicals.2,3 Common in both microorganisms and higher...oxygen, which will react with amino acid side chains and reduce protein stability. GFPuv is excited by long-wave UV and requires ionization for...vinyl sulfate, poly-4-styrenesulfonic acid , and humic acid ) were used to encapsulate E. coli cells expressing green fluorescent protein (GFP) either

Influence of Layer-by-Layer Polyelectrolyte Deposition and EDC/NHS Activated Heparin Immobilization onto Silk Fibroin Fabric

PubMed Central

Elahi, M. Fazley; Guan, Guoping; Wang, Lu; King, Martin W.

2014-01-01

To enhance the hemocompatibility of silk fibroin fabric as biomedical material, polyelectrolytes architectures have been assembled through the layer-by-layer (LbL) technique on silk fibroin fabric (SFF). In particular, 1.5 and 2.5 bilayer of oppositely charged polyelectrolytes were assembled onto SFF using poly(allylamine hydrochloride) (PAH) as polycationic polymer and poly(acrylic acid) (PAA) as polyanionic polymer with PAH topmost. Low molecular weight heparin (LMWH) activated with 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) was then immobilized on its surface. Alcian Blue staining, toluidine blue assay and X-ray photoelectron spectroscopy (XPS) confirmed the presence of heparin on modified SFF surfaces. The surface morphology of the modified silk fibroin fabric surfaces was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), and obtained increased roughness. Negligible hemolytic effect and a higher concentration of free hemoglobin by a kinetic clotting time test ensured the improved biological performance of the modified fibroin fabric. Overall, the deposition of 2.5 bilayer was found effective in terms of biological and surface properties of the modified fibroin fabric compared to 1.5 bilayer self-assembly technique. Therefore, this novel approach to surface modification may demonstrate long term patency in future in vivo animal trials of small diameter silk fibroin vascular grafts. PMID:28788601

An in-line Mach-Zehnder Interferometer Using Thin-core Fiber for Ammonia Gas Sensing With High Sensitivity

NASA Astrophysics Data System (ADS)

Huang, Xinyue; Li, Xueming; Yang, Jianchun; Tao, Chuanyi; Guo, Xiaogang; Bao, Hebin; Yin, Yanjun; Chen, Huifei; Zhu, Yuhua

2017-04-01

Ammonia is an important indicator among environmental monitoring parameters. In this work, thin-core fiber Mach-Zehnder interferometer deposited with poly (acrylic acid) (PAA), poly (allyamine hydrochloride) (PAH) and single-walled carbon nanotubes (SWCNTs-COOH) sensing film for the detection of ammonia gas has been presented. The thin-core fiber modal interferometer was made by fusion splicing a small section of thin-core fiber (TCF) between two standard single mode fibers (SMF). A beam propagation method (BPM) is employed for the design of proposed interferometer and numerical simulation. Based on the simulation results, interferometer with a length of 2 cm of thin-core fiber is fabricated and experimentally studied. (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film is deposited on the outer surface of thin-core fiber via layer-by-layer (LbL) self-assembly technique. The gas sensor coated with (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film towards NH3 gas exposure at concentrations range from 1 to 960 ppm are analyzed and the sensing capability is demonstrated by optical spectrum analyzer (OSA). Experimental results show that the characteristic wavelength shift has an approximately linear relationship in the range 1-20 ppm, which is in accordance with the numerical simulation. Thus, this paper reveals the potential application of this sensor in monitoring low concentration NH3 gas.

Nanostructured hydroxyapatite/poly(lactic-co-glycolic acid) composite coating for controlling magnesium degradation in simulated body fluid.

PubMed

Johnson, Ian; Akari, Khalid; Liu, Huinan

2013-09-20

Biodegradable magnesium (Mg) and its alloys have many attractive properties (e.g. comparable mechanical properties to cortical bone) for orthopedic implant applications, but they degrade too rapidly in the human body to meet clinical requirements. Nanostructured hydroxyapatite (nHA)/poly(lactic-co-glycolic acid) (PLGA) composite coatings provide synergistic properties for controlling degradation of Mg-based substrates and improving bone-implant integration. In this study, nHA/PLGA composites were spin coated onto Mg-based substrates and the results showed that the nHA/PLGA coatings retained nano-scale features with nHA dispersed in PLGA matrix. In comparison with non-coated Mg, the nHA/PLGA composite coated Mg increased the corrosion potential and decreased the corrosion current in revised simulated body fluid (rSBF). After 24 h of immersion in rSBF, increased calcium phosphate (CaP) deposition and formation of Mg-substituted CaP rosettes were observed on the surface of the nHA/PLGA coated Mg, indicating greater bioactivity. In contrast, no significant CaP was deposited on the PLGA coated Mg. Since both PLGA coating and nHA/PLGA coating showed some degree of delamination from Mg-based substrates during extended immersion in rSBF, the coating processing and properties should be further optimized in order to take full advantage of biodegradable Mg and nHA/PLGA nanocomposites for orthopedic applications.

Pt/glassy carbon model catalysts prepared from PS-b-P2VP micellar templates.

PubMed

Gu, Yunlong; St-Pierre, Jean; Ploehn, Harry J

2008-11-04

Poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymer was used as a micellar template to fabricate arrays of Pt nanoparticles on mica and glassy carbon (GC) supports. Polymer micellar deposition yields Pt nanoparticles with tunable particle size and surface number density on both mica and GC. After deposition of precursor-loaded micelles onto GC, oxygen plasma etching removes the polymer shell, followed by thermal treatment with H2 gas to reduce the Pt. Etching conditions were optimized to maximize removal of the polymer while minimizing damage to the GC. Arrays of Pt nanoparticles with controlled size and surface number density can be prepared on mica (for particle size characterization) and GC to make Pt/GC model catalysts. These model catalysts were characterized by tapping mode atomic force microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry to measure activity for oxidation of carbon monoxide or methanol. Cyclic voltammetry results demonstrate the existence of a correlation between Pt particle size and electrocatalytic properties including onset potential, tolerance of carbonaceous adsorbates, and intrinsic activity (based on active Pt area from CO stripping voltammetry). Results obtained with Pt/GC model catalysts duplicate prior results obtained with Pt/porous carbon catalysts therefore validating the synthesis approach and offering a new, tunable platform to study catalyst structure and other effects such as aging on proton exchange membrane fuel cell (PEMFC) reactions.

Microgroove and Collagen-poly(ε-caprolactone) Nanofiber Mesh Coating Improves the Mechanical Stability and Osseointegration of Titanium Implants

PubMed Central

Khandaker, Morshed; Riahinezhad, Shahram; Williams, Wendy R.; Wolf, Roman

2017-01-01

The effect of depositing a collagen (CG)-poly-ε-caprolactone (PCL) nanofiber mesh (NFM) at the microgrooves of titanium (Ti) on the mechanical stability and osseointegration of the implant with bone was investigated using a rabbit model. Three groups of Ti samples were produced: control Ti samples where there were no microgrooves or CG-PCL NFM, groove Ti samples where microgrooves were machined on the circumference of Ti, and groove-NFM Ti samples where CG-PCL NFM was deposited on the machined microgrooves. Each group of Ti samples was implanted in the rabbit femurs for eight weeks. The mechanical stability of the Ti/bone samples were quantified by shear strength from a pullout tension test. Implant osseointegration was evaluated by a histomorphometric analysis of the percentage of bone and connective tissue contact with the implant surface. The bone density around the Ti was measured by micro–computed tomography (μCT) analysis. This study found that the shear strength of groove-NFM Ti/bone samples was significantly higher compared to control and groove Ti/bone samples (p < 0.05) and NFM coating influenced the bone density around Ti samples. In vivo histomorphometric analyses show that bone growth into the Ti surface increased by filling the microgrooves with CG-PCL NFM. The study concludes that a microgroove assisted CG-PCL NFM coating may benefit orthopedic implants. PMID:28608839

The electrodeposition of multilayers on a polymeric substrate in Flexible Organic Light Emitting Diode (OLED)

NASA Astrophysics Data System (ADS)

Guedes, Andre F. S.; Guedes, Vilmar P.; Tartari, Simone; Cunha, Idaulo Jose

2016-09-01

The development of Organic Light Emitting Diode (OLED), using an optically transparent substrate material and organic semiconductor materials, has been widely utilized by the electronic industry when producing new technological products. The OLED are the base Poly(3,4-ethylenedioxythiophene), PEDOT, Poly(p-phenylenevinylene), PPV, and Polyaniline, PANI, were deposited in Indium Tin Oxide, ITO, and characterized by UV-Visible Spectroscopy (UV-Vis), Optical Parameters (OP) and Scanning Electron Microscopy (SEM). In addition, the thin film obtained by the deposition of PANI, prepared in perchloric acid solution, was identified through PANI-X1. The result obtained by UV-Vis has demonstrated that the PET/ITO/PEDOT/PPV/PANI-X1/Al layer does not have displacement of absorption for wavelengths greaters after spin-coating and electrodeposition. Thus, the spectral irradiance of the OLED informed the irradiance of 100 W/m2, and this result, compared with the standard Light Emitting Diode (LED), has indicated that the OLED has higher irradiance. After 1200 hours of electrical OLED tests, the appearance of nanoparticles visible for images by SEM, to the migration process of organic semiconductor materials, was present, then. Still, similar to the phenomenon of electromigration observed in connections and interconnections of microelectronic devices, the results have revealed a new mechanism of migration, which raises the passage of electric current in OLED.

Synthesis Al complex and investigating effect of doped ZnO nanoparticles in the electrical and optical efficiency of OLEDS

NASA Astrophysics Data System (ADS)

Shahedi, Zahra; Jafari, Mohammad Reza

2017-01-01

In this study, an organometallic complex based on aluminum ions is synthesized. And it is utilized as fluorescent material in the organic light-emitting diodes (OLEDs). The synthesized complex was characterized using XRD, UV-Vis, FT-IR as well as PL spectroscopy analyses. The energy levels of Al complex were determined by cyclic voltammetry measurements. Then, the effects of ZnO nanoparticles (NPs) of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate), PEDOT:PSS, on the electrical and optical performance of the organic light-emitting diodes have been investigated. For this purpose, two samples containing ITO/PEDOT:PSS/PVK/Alq3/PBD/Al with two different concentration and two samples containing ITO/PEDOT:PSS:ZnO/PVK/Alq3/PBD/Al with two different concentration were prepared. Then, hole transport, electron transport and emissive layers were deposited by the spin coating method and the cathode layer (Al) was deposited by the thermal evaporation method. The OLED simulation was also done by constructing the model and choosing appropriate parameters. Then, the experimental data were collected and the results interpreted both qualitatively and quantitatively. The results of the simulations were compared with experimental data of the J-V spectra. Comparing experimental data and simulation results showed that the electrical and optical efficiency of the samples with ZnO NPs is appreciably higher than the samples without ZnO NPs.

Characterisation of capacitive field-effect sensors with a nanocrystalline-diamond film as transducer material for multi-parameter sensing.

PubMed

Abouzar, M H; Poghossian, A; Razavi, A; Williams, O A; Bijnens, N; Wagner, P; Schöning, M J

2009-01-01

The feasibility of a capacitive field-effect EDIS (electrolyte-diamond-insulator-semiconductor) platform for multi-parameter sensing is demonstrated by realising EDIS sensors with an O-terminated nanocrystalline-diamond (NCD) film as transducer material for the detection of pH and penicillin concentration as well as for the label-free electrical monitoring of adsorption and binding of charged macromolecules, like polyelectrolytes. The NCD films were grown on p-Si-SiO(2) substrates by microwave plasma-enhanced chemical vapour deposition. To obtain O-terminated surfaces, the NCD films were treated in an oxidising medium. The NCD-based field-effect sensors have been characterised by means of constant-capacitance method. The average pH sensitivity of the O-terminated NCD film was 40 mV/pH. A low detection limit of 5 microM and a high penicillin G sensitivity of 65-70 mV/decade has been obtained for an EDIS penicillin biosensor with the adsorptively immobilised enzyme penicillinase. Alternating potential changes, having tendency to decrease with increasing the number of adsorbed polyelectrolyte layers, have been observed after the layer-by-layer deposition of polyelectrolyte multilayers, using positively charged PAH (poly (allylamine hydrochloride)) and a negatively charged PSS (poly (sodium 4-styrene sulfonate)) as a model system. The response mechanism of the developed EDIS sensors is discussed.

Pd-Cu/poly(o-Anisidine) nanocomposite as an efficient catalyst for formaldehyde oxidation

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

Hosseini, Sayed Reza, E-mail: r.hosseini@umz.ac.ir; Raoof, Jahan-Bakhsh; Ghasemi, Shahram

Highlights: • o-Anisidine monomer was electro-polymerized at the pCPE surface in acid medium. • Palladium/copper NPs were prepared by galvanic replacement method at the POA/pCPE. • Pd-Cu NPs showed excellent electrocatalytic activity towards formaldehyde oxidation. • The bimetallic Pd-Cu NPs/POA nanocomposite showed satisfactory long-term stability. - Abstract: In this work, for the first time, the electrocatalytic oxidation of formaldehyde in 0.5 M sulfuric acid solution at spherical bimetallic palladium-copper nanoparticles (Pd-Cu NPs) deposited on the poly (o-Anisidine) film modified electrochemically pretreated carbon paste electrode (POA/pCPE) has been investigated. Highly porous POA film prepared by electropolymerization onto the pCPE was usedmore » as a potent support for deposition of the Pd-Cu NPs. The Pd-Cu NPs were prepared through spontaneous and irreversible reaction via galvanic replacement between Pd{sup II} ions and the Cu{sup 0} particles. The prepared Pd-Cu NPs were characterized by scanning electron microscopy, energy dispersive spectroscopy and electrochemical methods. The obtained results showed that the utilization of Cu nanoparticles and pretreatment technique enhances the electrocatalytic activity of the modified electrode towards formaldehyde oxidation. The influence of several parameters on formaldehyde oxidation as well as stability of the Pd-Cu/POA/pCPE has been investigated.« less

Nanostructured hydroxyapatite/poly(lactic-co-glycolic acid) composite coating for controlling magnesium degradation in simulated body fluid

NASA Astrophysics Data System (ADS)

Johnson, Ian; Akari, Khalid; Liu, Huinan

2013-09-01

Biodegradable magnesium (Mg) and its alloys have many attractive properties (e.g. comparable mechanical properties to cortical bone) for orthopedic implant applications, but they degrade too rapidly in the human body to meet clinical requirements. Nanostructured hydroxyapatite (nHA)/poly(lactic-co-glycolic acid) (PLGA) composite coatings provide synergistic properties for controlling degradation of Mg-based substrates and improving bone-implant integration. In this study, nHA/PLGA composites were spin coated onto Mg-based substrates and the results showed that the nHA/PLGA coatings retained nano-scale features with nHA dispersed in PLGA matrix. In comparison with non-coated Mg, the nHA/PLGA composite coated Mg increased the corrosion potential and decreased the corrosion current in revised simulated body fluid (rSBF). After 24 h of immersion in rSBF, increased calcium phosphate (CaP) deposition and formation of Mg-substituted CaP rosettes were observed on the surface of the nHA/PLGA coated Mg, indicating greater bioactivity. In contrast, no significant CaP was deposited on the PLGA coated Mg. Since both PLGA coating and nHA/PLGA coating showed some degree of delamination from Mg-based substrates during extended immersion in rSBF, the coating processing and properties should be further optimized in order to take full advantage of biodegradable Mg and nHA/PLGA nanocomposites for orthopedic applications.

Human mesenchymal stem cell osteoblast differentiation, ECM deposition, and biomineralization on PAH/PAA polyelectrolyte multilayers.

PubMed

Pattabhi, Sudhakara Rao; Lehaf, Ali M; Schlenoff, Joseph B; Keller, Thomas C S

2015-05-01

Polyelectrolyte multilayer (PEMU) coatings built layer by layer with alternating pairs of polyelectrolytes can be tuned to improve cell interactions with surfaces and may be useful as biocompatible coatings to improve fixation between implants and tissues. Here, we show that human mesenchymal stromal cells (hMSCs) induced with bone differentiation medium (BDM) to become osteoblasts biomineralize crosslinked PEMUs built with the polycation poly(allylamine hydrochloride) (PAH) and the polyanion poly(acrylic acid) (PAA). Degrees of hMSC osteoblast differentiation and surface biomineralization on the smooth PAH-terminated PEMUs (PAH-PEMUs) and microstructured PAA-terminated PEMUs (PAA-PEMUs) reflect differences in cell-deposited extracellular matrix (ECM). BDM-induced hMSCs expressed higher levels of the early osteoblast differentiation marker alkaline phosphatase and collagen 1 (COL1) sooner on PAA-PEMUs than on PAH-PEMUs. Cells on both types of PEMUs proceeded to express the later stage osteoblast differentiation marker bone sialoprotein (BSP), but the BDM-induced cells organized a more amorphous Collagen I and denser BSP localization on PAA-PEMUs than on PAH-PEMUs. These ECM properties correlated with greater biomineralization on the PAA-PEMUs than on PAH-PEMUs. Together, these results confirm the suitability of PAH/PAA PEMUs as a substrate for hMSC osteogenesis and highlight the importance of substrate effects on ECM organization and BSP presentation on biomineralization. © 2014 Wiley Periodicals, Inc.

Synthesis of antireflective silica coatings through the synergy of polypeptide layer-by-layer assemblies and biomineralization

NASA Astrophysics Data System (ADS)

Lee, Yung-Lun; Lin, Ting-Xuan; Hsu, Feng-Ming; Jan, Jeng-Shiung

2016-01-01

We report a versatile approach to synthesize silica coatings with antireflective (AR) characteristics through the combination of a layer-by-layer (LbL) assembly technique and biomineralization. LbL assembled decanoyl-modified poly(l-lysine)/poly(l-glutamic acid) (PLL-g-Dec/PLGA) multilayer films were used as templates for silica mineralization, followed by calcination. The specific deposition of silica onto the LbL polypeptide assemblies through amine-catalyzed polycondensation resulted in silica coatings that exhibited the transcription of the nano-/microstructured polypeptide films and their film thickness and porosity can be tuned by varying the number of bilayers, degree of substitution, and PLL molecular weight. AR silica coatings exhibiting more than 6% increase in transmittance in the near UV/visible spectral range can be obtained at an optimized refractive index, thickness, and surface roughness. The abrasion test showed that the silica coatings exhibited sufficient structural durability due to continuous silica nanostructures and low surface roughness. This study demonstrated that nanostructured thin films can be synthesized for AR coatings using the synergy between the LbL assembly technique and biomineralization.We report a versatile approach to synthesize silica coatings with antireflective (AR) characteristics through the combination of a layer-by-layer (LbL) assembly technique and biomineralization. LbL assembled decanoyl-modified poly(l-lysine)/poly(l-glutamic acid) (PLL-g-Dec/PLGA) multilayer films were used as templates for silica mineralization, followed by calcination. The specific deposition of silica onto the LbL polypeptide assemblies through amine-catalyzed polycondensation resulted in silica coatings that exhibited the transcription of the nano-/microstructured polypeptide films and their film thickness and porosity can be tuned by varying the number of bilayers, degree of substitution, and PLL molecular weight. AR silica coatings exhibiting more than 6% increase in transmittance in the near UV/visible spectral range can be obtained at an optimized refractive index, thickness, and surface roughness. The abrasion test showed that the silica coatings exhibited sufficient structural durability due to continuous silica nanostructures and low surface roughness. This study demonstrated that nanostructured thin films can be synthesized for AR coatings using the synergy between the LbL assembly technique and biomineralization. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06948c

Engineering invitro cellular microenvironment using polyelectrolyte multilayer films to control cell adhesion and for drug delivery applications

NASA Astrophysics Data System (ADS)

Kidambi, Srivatsan

Over the past decades, the development of new methods for fabricating thin films that provide precise control of the three-dimensional topography and cell adhesion has generated lots of interest. These films could lead to significant advances in the fields of tissue engineering, drug delivery and biosensors which have become increasingly germane areas of research in the field of chemical engineering. The ionic layer-by-layer (LbL) assembly technique called "Polyelectrolyte Multilayers (PEMs)", introduced by Decher in 1991, has emerged as a versatile and inexpensive method of constructing polymeric thin films, with nanometer-scale control of ionized species. PEMs have long been utilized in such applications as sensors, eletrochromics, and nanomechanical thin films but recently they have also been shown to be excellent candidates for biomaterial applications. In this thesis, we engineered these highly customizable PEM thin films to engineer in vitro cellular microenvironments to control cell adhesion and for drug delivery applications. PEM films were engineered to control the adhesion of primary hepatocytes and primary neurons without the aid of adhesive proteins/ligands. We capitalized upon the differential cell attachment and spreading of primary hepatocytes and neurons on poly(diallyldimethylammoniumchloride) (PDAC) and sulfonated polystyrene (SPS) surfaces to make patterned co-cultures of primary hepatocytes/fibroblasts and primary neurons/astrocytes on the PEM surfaces. In addition, we developed self-assembled monolayer (SAM) patterns of m-d-poly(ethylene glycol) (m-dPEG) acid molecules onto PEMs. The created m-dPEG acid monolayer patterns on PEMs acted as resistive templates, and thus prevented further deposits of consecutive poly(anion)/poly(cation) pairs of charged particles and resulted in the formation of three-dimensional (3-D) patterned PEM films or selective particle depositions atop the original multilayer thin films. These new patterned and structured surfaces have potential applications in microelectronic devices and electro-optical and biochemical sensors. The PEG patterns developed are tunable at certain salt conditions and be removed from the PEM surface without affecting the PEM layers underneath the patterns. These removable surfaces provide an alternative method to form patterns of multiple particles, proteins and cells. This new approach provides an environmentally friendly and biocompatible route to designing versatile salt tunable surfaces. Finally, we illustrate the use of PEM films to engineer aptamer and siRNA based drug delivery systems.

Redox responsive nanotubes from organometallic polymers by template assisted layer by layer fabrication

NASA Astrophysics Data System (ADS)

Song, Jing; Jańczewski, Dominik; Guo, Yuanyuan; Xu, Jianwei; Vancso, G. Julius

2013-11-01

Redox responsive nanotubes were fabricated by the template assisted layer-by-layer (LbL) assembly method and employed as platforms for molecular payload release. Positively and negatively charged organometallic poly(ferrocenylsilane)s (PFS) were used to construct the nanotubes, in combination with other polyions. During fabrication, multilayers of these polyions were deposited onto the inner pores of template porous membranes, followed by subsequent removal of the template. Anodized porous alumina and track-etched polycarbonate membranes were used as templates. The morphology, electrochemistry, composition and other properties of the obtained tubular structure were characterized by fluorescence microscopy, scanning (SEM) and transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy. Composite nanotubes, consisting of poly(acrylic acid) anions with PFS+ and nanoparticles including fluorophore labelled dextran and decorated quantum dots, with PFS polyelectrolytes were also fabricated, broadening the scope of the structures. Cyclic voltammograms of PFS containing nanotubes showed similar redox responsive behaviour to thin LbL assembled films. Redox triggered release of labelled macromolecules from these tubular structures demonstrated application potential in controlled molecular delivery.Redox responsive nanotubes were fabricated by the template assisted layer-by-layer (LbL) assembly method and employed as platforms for molecular payload release. Positively and negatively charged organometallic poly(ferrocenylsilane)s (PFS) were used to construct the nanotubes, in combination with other polyions. During fabrication, multilayers of these polyions were deposited onto the inner pores of template porous membranes, followed by subsequent removal of the template. Anodized porous alumina and track-etched polycarbonate membranes were used as templates. The morphology, electrochemistry, composition and other properties of the obtained tubular structure were characterized by fluorescence microscopy, scanning (SEM) and transmission electron microscopy (TEM) and energy-dispersive X-ray (EDX) spectroscopy. Composite nanotubes, consisting of poly(acrylic acid) anions with PFS+ and nanoparticles including fluorophore labelled dextran and decorated quantum dots, with PFS polyelectrolytes were also fabricated, broadening the scope of the structures. Cyclic voltammograms of PFS containing nanotubes showed similar redox responsive behaviour to thin LbL assembled films. Redox triggered release of labelled macromolecules from these tubular structures demonstrated application potential in controlled molecular delivery. Electronic supplementary information (ESI) available: Nanotube wall thickness determination protocol. See DOI: 10.1039/c3nr03927g

Enhanced mechanical properties of low-surface energy thin films by simultaneous plasma polymerization of fluorine and epoxy containing polymers

NASA Astrophysics Data System (ADS)

Karaman, Mustafa; Uçar, Tuba

2016-01-01

Thin films of poly(2,2,3,4,4,4 hexafluorobutyl acrylate-glycidyl methacrylate) (P(HFBA-GMA) were deposited on different surfaces using an inductively coupled RF plasma reactor. Fluorinated polymer was used to impart hydrophobicity, whereas epoxy polymer was used for improved durability. The deposition at a low plasma power and temperature was suitable for the functionalization of fragile surfaces such as textile fabrics. The coated rough textile surfaces were found to be superhydrophobic with water contact angles greater than 150° due to the high retention of long fluorinated side chains. The hydrophobicity of the surfaces was observed to be stable after many exposures to ultrasonification tests, which is attributed to the mechanical durability of the films due to their epoxide functionality. FTIR and XPS analyses of the deposited films confirmed that the epoxide functionality of the polymers increased with increasing glycidyl methacrylate fraction in the reactor inlet. The modulus and hardness values of the films also increase with increasing epoxide functionality.

Dependence of the surface roughness of MAPLE-deposited films on the solvent parameters

NASA Astrophysics Data System (ADS)

Caricato, A. P.; Leggieri, G.; Martino, M.; Vantaggiato, A.; Valerini, D.; Cretì, A.; Lomascolo, M.; Manera, M. G.; Rella, R.; Anni, M.

2010-12-01

Matrix-assisted pulsed laser evaporation (MAPLE) was used to deposit layers of poly(9,9-dioctylfluorene) (PFO) to study the relation between the solvent properties (laser light absorption, boiling temperature and solubility parameters) and the morphology of the deposited films. To this end, the polymer was diluted (0.5 wt%) in tetrahydrofuran—THF, toluene and toluene/hexane mixtures. The thickness of the films was equal to 70±20 nm. The morphology and uniformity of the films was investigated by Atomic Force Microscopy and by the photoluminescence emission properties of the polymer films, respectively. It is shown that, although the solubility parameters of the solvents are important in controlling the film roughness and morphology, the optical absorption properties and boiling temperature play a very important role, too. In fact, for matrices characterized by the same total solubility parameter, lower roughness values are obtained for films prepared using solvents with lower penetration depth of the laser radiation and higher boiling temperatures.

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

Napari, Mari, E-mail: mari.napari@jyu.fi; Malm, Jari; Lehto, Roope

ZnO films were grown by atomic layer deposition at 35 °C on poly(methyl methacrylate) substrates using diethylzinc and water precursors. The film growth, morphology, and crystallinity were studied using Rutherford backscattering spectrometry, time-of-flight elastic recoil detection analysis, atomic force microscopy, scanning electron microscopy, and x-ray diffraction. The uniform film growth was reached after several hundreds of deposition cycles, preceded by the precursor penetration into the porous bulk and island-type growth. After the full surface coverage, the ZnO films were stoichiometric, and consisted of large grains (diameter 30 nm) with a film surface roughness up to 6 nm (RMS). The introduction of Al{sub 2}O{submore » 3} seed layer enhanced the initial ZnO growth substantially and changed the surface morphology as well as the crystallinity of the deposited ZnO films. Furthermore, the water contact angles of the ZnO films were measured, and upon ultraviolet illumination, the ZnO films on all the substrates became hydrophilic, independent of the film crystallinity.« less

p-Type semiconducting nickel oxide as an efficiency-enhancing anode interfacial layer in polymer bulk-heterojunction solar cells

PubMed Central

Irwin, Michael D.; Buchholz, D. Bruce; Hains, Alexander W.; Chang, Robert P. H.; Marks, Tobin J.

2008-01-01

To minimize interfacial power losses, thin (5–80 nm) layers of NiO, a p-type oxide semiconductor, are inserted between the active organic layer, poly(3-hexylthiophene) (P3HT) + [6,6]-phenyl-C61 butyric acid methyl ester (PCBM), and the ITO (tin-doped indium oxide) anode of bulk-heterojunction ITO/P3HT:PCBM/LiF/Al solar cells. The interfacial NiO layer is deposited by pulsed laser deposition directly onto cleaned ITO, and the active layer is subsequently deposited by spin-coating. Insertion of the NiO layer affords cell power conversion efficiencies as high as 5.2% and enhances the fill factor to 69% and the open-circuit voltage (Voc) to 638 mV versus an ITO/P3HT:PCBM/LiF/Al control device. The value of such hole-transporting/electron-blocking interfacial layers is clearly demonstrated and should be applicable to other organic photovoltaics.

Chemical solution-deposited PbZr 0.53 Ti 0.47 O3 on La 0.5 Sr 0.5 Co O3. SIMS investigation of the effect of different precursor additives on the layer structure.

PubMed

Pollak, C; Malic, B; Kosec, M; Javoric, S; Hutter, H

2002-10-01

Chemical solution-deposited thin films of PbZr(0.53)Ti(0.47)O(3)/La(0.5)Sr(0.5)CoO(3) on Pt/TiO(2)/SiO(2)/Si substrates have been investigated by dynamic SIMS. The PbZr(0.53)Ti(0.47)O(3) (PZT) is intended to serve as a ferroelectric layer for microelectronic or microelectromechanical applications; conducting La(0.5)Sr(0.5)CoO(3) (LSCO) is a buffer layer intended to eliminate fatigue effects which usually occur at the Pt/PZT interface. Depth profiles of the main components were obtained and revealed that significant diffusion occurred during the deposition and crystallisation processes. Two types of sample, with different thickness of PZT and different types of poly(vinyl alcohol) (PVA) added to the LSCO precursor, were investigated.

Surfactant Driven Post-Deposition Spreading of Aerosols on Complex Aqueous Subphases. 2: Low Deposition Flux Representative of Aerosol Delivery to Small Airways

PubMed Central

Sharma, Ramankur; Khanal, Amsul; Corcoran, Timothy E.; Przybycien, Todd M.; Tilton, Robert D.

2015-01-01

Abstract Background: Cystic fibrosis (CF) is associated with the accumulation of dehydrated mucus in the pulmonary airways. This alters ventilation and aerosol deposition patterns in ways that limit drug delivery to peripheral lung regions. We investigated the use of surfactant-based, self-dispersing aerosol carriers that produce surface tension gradients to drive two-dimensional transport of aerosolized medications via Marangoni flows after deposition on the airway surface liquid (ASL). We considered the post-deposition spreading of individual aerosol droplets and two-dimensional expansion of a field of aerosol droplets, when deposited at low fluxes that are representative of aerosol deposition in the small airways. Methods: We used physically entangled aqueous solutions of poly(acrylamide) or porcine gastric mucin as simple ASL mimics that adequately capture the full miscibility but slow penetration of entangled macromolecular chains of the ASL into the deposited drop. Surfactant formulations were prepared with aqueous solutions of nonionic tyloxapol or FS-3100 fluorosurfactant. Fluorescein dye served as a model “drug” tracer and to visualize the extent of post-deposition spreading. Results: The surfactants not only enhanced post-deposition spreading of individual aerosol droplets due to localized Marangoni stresses, as previously observed with macroscopic drops, but they also produced large-scale Marangoni stresses that caused the deposited aerosol fields to expand into initially unexposed regions of the subphase. We show that the latter is the main mechanism for spreading drug over large distances when aerosol is deposited at low fluxes representative of the small airways. The large scale convective expansion of the aerosol field drives the tracer (drug mimic) over areas that would cover an entire airway generation or more, in peripheral airways, where sub-monolayer droplet deposition is expected during aerosol inhalation. Conclusions: The results suggest that aerosolized surfactant formulations may provide the means to maximize deposited drug uniformity in and access to small airways. PMID:25757067

Nanoimprint Lithography on curved surfaces prepared by fused deposition modelling

NASA Astrophysics Data System (ADS)

Köpplmayr, Thomas; Häusler, Lukas; Bergmair, Iris; Mühlberger, Michael

2015-06-01

Fused deposition modelling (FDM) is an additive manufacturing technology commonly used for modelling, prototyping and production applications. The achievable surface roughness is one of its most limiting aspects. It is however of great interest to create well-defined (nanosized) patterns on the surface for functional applications such as optical effects, electronics or bio-medical devices. We used UV-curable polymers of different viscosities and flexible stamps made of poly(dimethylsiloxane) (PDMS) to perform Nanoimprint Lithography (NIL) on FDM-printed curved parts. Substrates with different roughness and curvature were prepared using a commercially available 3D printer. The nanoimprint results were characterized by optical light microscopy, profilometry and atomic force microscopy (AFM). Our experiments show promising results in creating well-defined microstructures on the 3D-printed parts.

Growth of polymer-metal nanocomposites by pulsed laser deposition

NASA Astrophysics Data System (ADS)

Röder, Johanna; Faupel, Jörg; Krebs, Hans-Ulrich

2008-12-01

Complex polymer-metal nanocomposites have a wide range of applications, e.g. as flexible displays and packaging materials. Pulsed laser deposition was applied to form nanostructured materials consisting of metal clusters (Ag, Au, Pd and Cu) embedded in a polymer (polycarbonate, PC) matrix. The size and amount of the metal clusters are controlled by the number of laser pulses hitting the respective targets. For Cu and Pd, smaller clusters and higher cluster densities are obtained as in the cases of Ag and Au due to a stronger reactivity with the polymers and thus a lower diffusivity. Implantation effects, differences in metal diffusivity and reactivity on the polymer surfaces, and the coalescence properties are discussed with respect to the observed microstructures on PC and compared to the metal growth on poly (methyl methacrylate), PMMA.

Perovskite LaBaCo2O5+δ (LBCO) single-crystal thin films for pressure sensing applications

NASA Astrophysics Data System (ADS)

Ma, Y. J.; Xiao, J. Y.; Zhang, Q. Y.; Ma, C. Y.; Jiang, X. N.; Wu, B. Y.; Zeng, X. Y.

2018-04-01

Perovskite LaBaCo2O5+δ (LBCO) single-crystal films were deposited on (001) MgO substrates by a magnetron sputtering method and processed into Pirani sensors for investigation of pressure measurements. In comparison to the poly-crystal film deposited under the same condition, the single-crystal LBCO films exhibited rather a large temperature coefficient of resistance and a high sensitivity in response to pressure. The LBCO sensors with dimensions of 30 to 200 μm, which are different from resistor-on-dielectric membrane or micro-beam structures, demonstrated to be capable of making response to the pressures ranging from 5 × 10-2 to 105 Pa with a real dynamic range of 3 to 2 × 103 Pa.

Plasma deposition of silver nanoparticles on ultrafiltration membranes: antibacterial and anti-biofouling properties.

PubMed

Cruz, Mercedes Cecilia; Ruano, Gustavo; Wolf, Marcus; Hecker, Dominic; Vidaurre, Elza Castro; Schmittgens, Ralph; Rajal, Verónica Beatriz

2015-02-01

A novel and versatile plasma reactor was used to modify Polyethersulphone commercial membranes. The equipment was applied to: i) functionalize the membranes with low-temperature plasmas, ii) deposit a film of poly(methyl methacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, iii) deposit silver nanoparticles (SNP) by Gas Flow Sputtering. Each modification process was performed in the same reactor consecutively, without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electron microscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the membrane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays by X-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treated membranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive ( Enterococcus faecalis ) and -negative ( Salmonella Typhimurium) bacteria. Therefore, disinfection by ultrafiltration showed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a more efficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To the best of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedure in order to deposit SNP on commercial membranes to inhibit biofouling formation.

Hierarchical templating in deposition of semi-covalently imprinted inverse opal polythiophene film for femtomolar determination of human serum albumin.

PubMed

Dabrowski, Marcin; Cieplak, Maciej; Sharma, Piyush Sindhu; Borowicz, Pawel; Noworyta, Krzysztof; Lisowski, Wojciech; D'Souza, Francis; Kuhn, Alexander; Kutner, Wlodzimierz

2017-08-15

Nanostructured artificial receptor materials with unprecedented hierarchical structure for determination of human serum albumin (HSA) are designed and fabricated. For that purpose a new hierarchical template is prepared. This template allowed for simultaneous structural control of the deposited molecularly imprinted polymer (MIP) film on three length scales. A colloidal crystal templating with optimized electrochemical polymerization of 2,3'-bithiophene enables deposition of an MIP film in the form of an inverse opal. Thickness of the deposited polymer film is precisely controlled with the number of current oscillations during potentiostatic deposition of the imprinted poly(2,3'-bithiophene) film. Prior immobilization of HSA on the colloidal crystal allows formation of molecularly imprinted cavities exclusively on the internal surface of the pores. Furthermore, all binding sites are located on the surface of the imprinted cavities at locations corresponding to positions of functional groups present on the surface of HSA molecules due to prior derivatization of HSA molecules with appropriate functional monomers. This synergistic strategy results in a material with superior recognition performance. Integration of the MIP film as a recognition unit with a sensitive extended-gate field-effect transistor (EG-FET) transducer leads to highly selective HSA determination in the femtomolar concentration range. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasma deposition of silver nanoparticles on ultrafiltration membranes: antibacterial and anti-biofouling properties

PubMed Central

Cruz, Mercedes Cecilia; Ruano, Gustavo; Wolf, Marcus; Hecker, Dominic; Vidaurre, Elza Castro; Schmittgens, Ralph; Rajal, Verónica Beatriz

2015-01-01

A novel and versatile plasma reactor was used to modify Polyethersulphone commercial membranes. The equipment was applied to: i) functionalize the membranes with low-temperature plasmas, ii) deposit a film of poly(methyl methacrylate) (PMMA) by Plasma Enhanced Chemical Vapor Deposition (PECVD) and, iii) deposit silver nanoparticles (SNP) by Gas Flow Sputtering. Each modification process was performed in the same reactor consecutively, without exposure of the membranes to atmospheric air. Scanning electron microscopy and transmission electron microscopy were used to characterize the particles and modified membranes. SNP are evenly distributed on the membrane surface. Particle fixation and transport inside membranes were assessed before- and after-washing assays by X-ray photoelectron spectroscopy depth profiling analysis. PMMA addition improved SNP fixation. Plasma-treated membranes showed higher hydrophilicity. Anti-biofouling activity was successfully achieved against Gram-positive (Enterococcus faecalis) and -negative (Salmonella Typhimurium) bacteria. Therefore, disinfection by ultrafiltration showed substantial resistance to biofouling. The post-synthesis functionalization process developed provides a more efficient fabrication route for anti-biofouling and anti-bacterial membranes used in the water treatment field. To the best of our knowledge, this is the first report of a gas phase condensation process combined with a PECVD procedure in order to deposit SNP on commercial membranes to inhibit biofouling formation. PMID:26166926

Liquid crystal colloidal structures for increased silicone deposition efficiency on colour-treated hair.

PubMed

Brown, M A; Hutchins, T A; Gamsky, C J; Wagner, M S; Page, S H; Marsh, J M

2010-06-01

An approach is described to increase the deposition efficiency of silicone conditioning actives from a shampoo on colour-treated hair via liquid crystal (LC) colloidal structures, created with a high charge density cationic polymer, poly(diallyldimethyl ammonium chloride) and negatively charged surfactants. LCs are materials existing structurally between the solid crystalline and liquid phases, and several techniques, including polarized light microscopy, small angle X-Ray analysis, and differential scanning calorimetry, were used to confirm the presence of the LC structures in the shampoo formula. Silicone deposition from the LC-containing shampoo and a control shampoo was measured on a range of hair substrates, and data from inductively coupled plasma optical emission spectroscopy analysis and ToF-SIMS imaging illustrate the enhancement in silicone deposition for the LC shampoo on all hair types tested, with the most pronounced enhancement occurring on hair that had undergone oxidative treatments, such as colouring. A model is proposed in which the LC structure deposits from the shampoo onto the hair to: (i) provide 'slip planes' along the hair surface for wet conditioning purposes and (ii) form a hydrophobic layer which changes the surface energy of the fibres. This increase in hydrophobicity of the hair surface thereby increases the deposition efficiency of silicone conditioning ingredients. Zeta potential measurements, dynamic absorbency testing analysis and ToF-SIMS imaging were used to better understand the mechanisms of action. This approach to increasing silicone deposition is an improvement relative to conventional conditioning shampoos, especially for colour-treated hair.

Absorptive carbon nanotube electrodes: Consequences of optical interference loss in thin film solar cells

NASA Astrophysics Data System (ADS)

Tait, Jeffrey G.; de Volder, Michaël F. L.; Cheyns, David; Heremans, Paul; Rand, Barry P.

2015-04-01

A current bottleneck in the thin film photovoltaic field is the fabrication of low cost electrodes. We demonstrate ultrasonically spray coated multiwalled carbon nanotube (CNT) layers as opaque and absorptive metal-free electrodes deposited at low temperatures and free of post-deposition treatment. The electrodes show sheet resistance as low as 3.4 Ω □-1, comparable to evaporated metallic contacts deposited in vacuum. Organic photovoltaic devices were optically simulated, showing comparable photocurrent generation between reflective metal and absorptive CNT electrodes for photoactive layer thickness larger than 600 nm when using archetypal poly(3-hexylthiophene) (P3HT) : (6,6)-phenyl C61-butyric acid methyl ester (PCBM) cells. Fabricated devices clearly show that the absorptive CNT electrodes display comparable performance to solution processed and spray coated Ag nanoparticle devices. Additionally, other candidate absorber materials for thin film photovoltaics were simulated with absorptive contacts, elucidating device design in the absence of optical interference and reflection.A current bottleneck in the thin film photovoltaic field is the fabrication of low cost electrodes. We demonstrate ultrasonically spray coated multiwalled carbon nanotube (CNT) layers as opaque and absorptive metal-free electrodes deposited at low temperatures and free of post-deposition treatment. The electrodes show sheet resistance as low as 3.4 Ω □-1, comparable to evaporated metallic contacts deposited in vacuum. Organic photovoltaic devices were optically simulated, showing comparable photocurrent generation between reflective metal and absorptive CNT electrodes for photoactive layer thickness larger than 600 nm when using archetypal poly(3-hexylthiophene) (P3HT) : (6,6)-phenyl C61-butyric acid methyl ester (PCBM) cells. Fabricated devices clearly show that the absorptive CNT electrodes display comparable performance to solution processed and spray coated Ag nanoparticle devices. Additionally, other candidate absorber materials for thin film photovoltaics were simulated with absorptive contacts, elucidating device design in the absence of optical interference and reflection. Electronic supplementary information (ESI) available: An animation of the MWCNT spray coating process, and five figures, including: a photograph of completed devices with MWCNT electrodes, performance metrics for devices with photoactive layer thickness up to 3000 nm, contour plots of simulated devices used to build Fig. 5, simulation data for perovskite devices, and a contour plot of the simplified equation of photoactive layer thickness required to attain a specified photocurrent ratio (x-axis) and absorption coefficient (y-axis). See DOI: 10.1039/c5nr01119a

Design and Processing of Structural Composite Batteries

DTIC Science & Technology

2007-09-01

The woven fabric, e is 72wt% LiFePO4 , 8wt% acetylene lack, and 20wt% poly(ethylene oxide) 200k as a binder. Acetylene black ensures electrical will...2.1.3 Cathode The composite cathode material utilizes LiFePO4 chemistry. The composition of the cathode material film deposited onto the metal substrat... LiFePO4 chemistry (over a 2.8-4.0V range (8)) including stainless steel and titanium. Stainless steel was evaluated in this udy due to its high

Aluminum induced crystallization of amorphous Ge thin films on insulating substrate

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

Singh, Ch. Kishan, E-mail: kisn@igcar.gov.in; Tah, T.; Sunitha, D. T.

2016-05-23

Aluminium (metal) induced crystallization of amorphous Ge in bilayer and multilayer Ge/Al thin films deposited on quartz substrate at temperature well below the crystallization temperature of bulk Ge is reported. The crystallization of poly-Ge proceeds via formations of dendritic crystalline Ge grains in the Al matrix. The observed phases were characterized by Raman spectroscopy and X-ray diffraction. The microstructure of Al thin film layer was found to have a profound influence on such crystallization process and formation of dendritic grains.

Preparation and Properties of Polyurethane and Polyurethaneurea Elastomers from Methylene Bis(4-Cyclohexylisocyanate).

DTIC Science & Technology

1983-10-01

EMILY A. MCHUGH , RICHARD W. MATTON, MARK A. CLEAVES, DANIEL P. MACK, and NATHANIEL S. SCHNEIDER POLYMER RESEARCH DIVISION Octoer 1983 DT’C E’’ i 0...AUTHOR(e) S. CONTRACT OR GRANT NUMBER(O) Catherine A. Byrne, Emily A. McHugh , Richard W. Matton, Mark A. Cleaves, Daniel P. Mack,* and Nathaniel S...impregnated Poly-plating, Inc. see text electroless nickel 4610 Westover Rd. Westover Industrial Air Park Chicopee, MA 01022 Plasm-deposited Dr. N. Morosoff

A sensitive electrochemical immunosensor based on poly(2-aminobenzylamine) film modified screen-printed carbon electrode for label-free detection of human immunoglobulin G.

PubMed

Putnin, Thitirat; Jumpathong, Watthanachai; Laocharoensuk, Rawiwan; Jakmunee, Jaroon; Ounnunkad, Kontad

2018-08-01

This work focuses on fabricating poly(2-aminobenzylamine)-modified screen-printed carbon electrode as an electrochemical immunosensor for the label-free detection of human immunoglobulin G. To selectively detect immunoglobulin G, the anti-immunoglobulin G antibody with high affinity to immunoglobulin G was covalently linked with the amine group of poly(2-aminobenzylamine) film-deposited screen-printed carbon electrode. The selectivity for immunoglobulin G was subsequently assured by being challenged with redox-active interferences and adventitious adsorption did not significantly interfere the analyte signal. To obviate the use of costly secondary antibody, the [Fe(CN) 6 ] 4-/3- redox probe was instead applied to measure the number of human immunoglobulin G through the immunocomplex formation that is quantitatively related to the level of the differential pulse voltammetric current. The resulting immunosensor exhibited good sensitivity with the detection limit of 0.15 ng mL -1 , limit of quantitation of 0.50 ng mL -1 and the linear range from 1.0 to 50 ng mL -1 . Given those striking analytical performances and the affordability arising from using cheap screen-printed carbon electrode with label-free detection, the immunosensor serves as a promising model for the next-step development of a diagnostic tool.

PLGA-loaded nanomedicines in melanoma treatment: Future prospect for efficient drug delivery

PubMed Central

Das, Sreemanti; Khuda-Bukhsh, Anisur Rahman

2016-01-01

Current treatment methods for melanoma have some limitations such as less target-specific action, severe side effects and resistance to drugs. Significant progress has been made in exploring novel drug delivery systems based on suitable biochemical mechanisms using nanoparticles ranging from 10 to 400 nm for drug delivery and imaging, utilizing their enhanced penetration and retention properties. Poly-lactide-co-glycolide (PLGA), a copolymer of poly-lactic acid and poly-glycolic acid, provides an ideally suited performance-based design for better penetration into skin cells, thereby having a greater potential for the treatment of melanoma. Moreover, encapsulation protects the drug from deactivation by biological reactions and interactions with biomolecules, ensuring successful delivery and bioavailability for effective treatment. Controlled and sustained delivery of drugs across the skin barrier that otherwise prohibits entry of larger molecules can be successfully made with adequately stable biocompatible nanocarriers such as PLGA for taking drugs through the small cutaneous pores permitting targeted deposition and prolonged drug action. PLGA is now being extensively used in photodynamic therapy and targeted therapy through modulation of signal proteins and drug-DNA interactions. Recent advances made on these nanomedicines and their advantages in the treatment of skin melanoma are highlighted and discussed in this review. PMID:27934796

Poly(acrylonitrile)chitosan composite membranes for urease immobilization.

PubMed

Gabrovska, Katya; Georgieva, Aneliya; Godjevargova, Tzonka; Stoilova, Olya; Manolova, Nevena

2007-05-10

(Poly)acrylonitrile/chitosan (PANCHI) composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of PAN and PANCHI membranes were determined by TEM and SEM analyses. It was found that the average size of the pore under a selective layer base PAN membrane is 7 microm, while the membrane coated with 0.25% chitosan shows a reduced pore size--small or equal to 5 microm and with 0.35% chitosan--about 4 microm. The amounts of the functional groups, the degree of hydrophilicity and transport characteristics of PAN/Chitosan composite membranes were determined. Urease was covalently immobilized onto all kinds of PAN/chitosan composite membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity (94%) was measured for urease bound to PANCHI2 membranes (0.25% chitosan). The basic characteristics (pH(opt), pH(stability), T(opt), T(stability), heat inactivation and storage stability) of immobilized urease were determined. The obtained results show that the poly(acrylonitrile)chitosan composite membranes are suitable for enzyme immobilization.

Visible-to-NIR Electrochromic Device Prepared from a Thermally Polymerizable Electroactive Organic Monomer.

PubMed

Wałęsa-Chorab, Monika; Skene, W G

2017-06-28

A monomer (1) consisting of a benzothiadiazole core flanked by two triphenylamines and two styrene pendant moieties was prepared. The monomer was fluorescent with its emission spanning 145 nm in the visible, contingent on the organic solvent used for the measurement. In addition to its positive solvatochromism, the absolute fluorescence quantum yield (Φ fl ) was consistently >20% with values >80% being measured in hexane, toluene, diethyl ether, and toluene. 1 could be reversibly oxidized with an oxidation potential of 880 mV vs SCE. The monomer could be immobilized on ITO-coated glass substrates. The resulting 425 nm thick immobilized film (poly-1) was 15% thinner than the monomer coating deposited by spray- and spin-coating. The electroactive film did not delaminate from the electrode upon either washing or cycling electrochemically between its oxidized and neutral states. Its absorption at 460 nm bleached upon electrochemical oxidation with the formation of a strong absorption at 880 nm and in the NIR, similar to 1. The perceived reversible color change with applied potential switched between yellow and gray. The fluorescence intensity of poly-1 could be switched with applied potentials. A passive transmissive device prepared from poly-1 was both electrochromic and fluorochromic, exhibiting reversible color change and fluorescence quenching.

Differentially pumped spray deposition as a rapid screening tool for organic and perovskite solar cells.

PubMed

Jung, Yen-Sook; Hwang, Kyeongil; Scholes, Fiona H; Watkins, Scott E; Kim, Dong-Yu; Vak, Doojin

2016-02-08

We report a spray deposition technique as a screening tool for solution processed solar cells. A dual-feed spray nozzle is introduced to deposit donor and acceptor materials separately and to form blended films on substrates in situ. Using a differential pump system with a motorised spray nozzle, the effect of film thickness, solution flow rates and the blend ratio of donor and acceptor materials on device performance can be found in a single experiment. Using this method, polymer solar cells based on poly(3-hexylthiophene) (P3HT):(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) are fabricated with numerous combinations of thicknesses and blend ratios. Results obtained from this technique show that the optimum ratio of materials is consistent with previously reported values confirming this technique is a very useful and effective screening method. This high throughput screening method is also used in a single-feed configuration. In the single-feed mode, methylammonium iodide solution is deposited on lead iodide films to create a photoactive layer of perovskite solar cells. Devices featuring a perovskite layer fabricated by this spray process demonstrated a power conversion efficiencies of up to 7.9%.

Novel procedure to enhance PLA surface properties by chitosan irreversible immobilization

NASA Astrophysics Data System (ADS)

Stoleru, Elena; Dumitriu, Raluca Petronela; Munteanu, Bogdanel Silvestru; Zaharescu, Traian; Tănase, Elisabeta Elena; Mitelut, Amalia; Ailiesei, Gabriela-Liliana; Vasile, Cornelia

2016-03-01

A novel two step procedure was applied for poly(lactic acid) (PLA) functionalization consisting in the exposure to cold radiofrequency plasma in nitrogen atmosphere or to gamma irradiation followed by ;grafting to; of a chitosan layer using carbodiimide chemistry. The adhesion and stability of the deposited surface layer was assured by plasma/gamma irradiation treatment while the chitosan layer offers antifungal/antibacterial/antioxidant activities. Chitosan with different viscosities/deacetylation degree was deposited by electrospinning or immersion methods. Correlations between rheological behavior of chitosan solutions and chitosan layer deposition conditions are made. The PLA surface properties were investigated by water contact angle measurements, ATR-FTIR spectroscopy, AFM, chemiluminiscence, etc. It has been established that the surface roughness increases direct proportional with cold plasma duration and gamma irradiation dose and further increases by chitosan coating which at its turn depends on chitosan characteristics (viscosity and deacetylation degree) and method of deposition. Nano-fibers with relatively homogeneous and reproducible features are obtained by electrospinning of highly viscous chitosan while with the other two types of chitosan both microparticles and nano-fibers are formed. The chitosan coating obtained by immersion is more homogenous and compact and has a better antibacterial activity than the electrospun layer as fiber meshes.

Electro-induced protein deposition on low-fouling surfaces

NASA Astrophysics Data System (ADS)

Cole, M. A.; Voelcker, N. H.; Thissen, H.

2007-12-01

Control over protein adsorption is a key issue for numerous biomedical applications ranging from diagnostic microarrays to tissue-engineered medical devices. Here, we describe a method for creating surfaces that prevent non-specific protein adsorption, which upon application of an external trigger can be transformed into surfaces showing high protein adsorption on demand. Silicon wafers were used as substrate materials upon which thin functional coatings were constructed by the deposition of an allylamine plasma polymer followed by high-density grafting of poly(ethylene oxide) aldehyde, resulting in a low-fouling surface. When the underlying highly doped silicon substrate was used as an electrode, the resulting electrostatic attraction between the electrode and charged proteins in solution induced protein deposition at the low-fouling interface. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to characterize the surface modifications. Controlled protein adsorption experiments were carried out using horseradish peroxidase. The amount of protein deposited at the surface was then investigated by means of a colorimetric assay. It is expected that the concept described here will find use in a variety of biotechnological and biomedical applications, particularly in the area of biochips.

Differentially pumped spray deposition as a rapid screening tool for organic and perovskite solar cells

PubMed Central

Jung, Yen-Sook; Hwang, Kyeongil; Scholes, Fiona H.; Watkins, Scott E.; Kim, Dong-Yu; Vak, Doojin

2016-01-01

We report a spray deposition technique as a screening tool for solution processed solar cells. A dual-feed spray nozzle is introduced to deposit donor and acceptor materials separately and to form blended films on substrates in situ. Using a differential pump system with a motorised spray nozzle, the effect of film thickness, solution flow rates and the blend ratio of donor and acceptor materials on device performance can be found in a single experiment. Using this method, polymer solar cells based on poly(3-hexylthiophene) (P3HT):(6,6)-phenyl C61 butyric acid methyl ester (PC61BM) are fabricated with numerous combinations of thicknesses and blend ratios. Results obtained from this technique show that the optimum ratio of materials is consistent with previously reported values confirming this technique is a very useful and effective screening method. This high throughput screening method is also used in a single-feed configuration. In the single-feed mode, methylammonium iodide solution is deposited on lead iodide films to create a photoactive layer of perovskite solar cells. Devices featuring a perovskite layer fabricated by this spray process demonstrated a power conversion efficiencies of up to 7.9%. PMID:26853266

Polymer coating behavior of Rayleigh-SAW resonators with gold electrode structure for gas sensor applications.

PubMed

Avramov, Ivan D; Länge, Kerstin; Rupp, Swen; Rapp, Bastian; Rapp, Michael

2007-01-01

Results from systematic polymer coating experiments on surface acoustic wave (SAW) resonators and coupled resonator filters (CRF) on ST-cut quartz with a corrosion-proof electrode structure entirely made of gold (Au) are presented and compared with data from similar SAW devices using aluminium (Al) electrodes. The recently developed Au devices are intended to replace their earlier Al counterparts in sensor systems operating in highly reactive chemical gas environments. Solid parylene C and soft poly[chlorotrifluoroethylene-co-vinylidene fluoride] (PCFV) polymer films are deposited under identical conditions onto the surface of Al and Au devices. The electrical performance of the Parylene C coated devices is monitored online during film deposition. The PCVF coated devices are evaluated after film deposition. The experimental data show that the Au devices can stand up to 40% thicker solid films for the same amount of loss increase than the Al devices and retain better resonance and phase characteristics. The frequency sensitivities of Au and Al devices to parylene C deposition are nearly identical. After coating with soft PCFV sensing film, the Au devices provide up to two times higher gas sensitivity when probed with cooling agent, octane, or tetrachloroethylene.

pH-responsive ion transport in polyelectrolyte multilayers of poly(diallyldimethylammonium chloride) (PDADMAC) and poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA) bearing strong- and weak anionic groups.

PubMed

Maza, Eliana; Tuninetti, Jimena S; Politakos, Nikolaos; Knoll, Wolfgang; Moya, Sergio; Azzaroni, Omar

2015-11-28

The layer-by-layer construction of interfacial architectures displaying stimuli-responsive control of mass transport is attracting increasing interest in materials science. In this work, we describe the creation of interfacial architectures displaying pH-dependent ionic transport properties which until now have not been observed in polyelectrolyte multilayers. We describe a novel approach to create pH-controlled ion-rectifying systems employing polyelectrolyte multilayers assembled from a copolymer containing both weakly and strongly charged pendant groups, poly(4-styrenesulfonic acid-co-maleic acid) (PSS-MA), alternately deposited with poly(diallyldimethylammonium chloride) (PDADMAC). The conceptual framework is based on the very contrasting and differential interactions of PSS and MA units with PDADMAC. In our setting, sulfonate groups play a structural role by conferring stability to the multilayer due to the strong electrostatic interactions with the polycations, while the weakly interacting MA groups remain "silent" within the film and then act as on-demand pH-responsive units. When these multilayers are combined with a strong cationic capping layer that repels the passage of cationic probes, a pH-gateable rectified transport of anions is observed. Concomitantly, we also observed that these functional properties are significantly affected when multilayers are subjected to extensive pH cycling as a consequence of irreversible morphological changes taking place in the film. We envision that the synergy derived from combining weak and strong interactions within the same multilayer will play a key role in the construction of new interfacial architectures displaying tailorable ion transport properties.

Effects of poly(2-hydroxyethyl methacrylate) and poly(vinyl-pyrrolidone) hydrogel implants on myopic and normal chick sclera

PubMed Central

Su, James; Iomdina, Elena; Tarutta, Elena; Ward, Brian; Song, Jie; Wildsoet, Christine F.

2008-01-01

There has been generally little attention paid to the utilization of biomaterials as an anti-myopia treatment. The purpose of this study was to investigate whether polymeric hydrogels, either implanted or injected adjacent to the outer scleral surface, slow ocular elongation. White Leghorn (gallus gallus domesticus) chicks were used at 2 weeks of age. Chicks had either (1) strip of poly(2-hydroxyethyl methacrylate) (pHEMA) implanted monocularly against the outer sclera at the posterior pole, or (2) an in situ polymerizing gel [main ingredient: poly(vinyl-pyrrolidone) (PVP)] injected monocularly at the same location. Some of the eyes injected with the polymer were fitted with a diffuser or a −10D lens. In each experiment, ocular lengths were measured at regular intervals by high frequency A-scan ultrasonography, and chicks were sacrificed for histology at staged intervals. No in vivo signs of either orbital or ocular inflammation were observed. The pHEMA implant significantly increased scleral thickness by the third week, and the implant became encapsulated with fibrous tissue. The PVP-injected eyes left otherwise untreated, showed a significant increase in scleral thickness, due to increased chondrocyte proliferation and extracellular matrix deposition. However, there was no effect of the PVP injection on ocular elongation. In eyes wearing optical devices, there was no effect on either scleral thickness or ocular elongation. These results represent “proof of principle” that scleral growth can be manipulated without adverse inflammatory responses. However, since neither approach slowed ocular elongation, additional factors must influence scleral surface area expansion in the avian eye. PMID:19109950

Biomimetic poly(amidoamine) hydrogels as synthetic materials for cell culture

PubMed Central

Jacchetti, Emanuela; Emilitri, Elisa; Rodighiero, Simona; Indrieri, Marco; Gianfelice, Antonella; Lenardi, Cristina; Podestà, Alessandro; Ranucci, Elisabetta; Ferruti, Paolo; Milani, Paolo

2008-01-01

Background Poly(amidoamine)s (PAAs) are synthetic polymers endowed with many biologically interesting properties, being highly biocompatible, non toxic and biodegradable. Hydrogels based on PAAs can be easily modified during the synthesis by the introduction of functional co-monomers. Aim of this work is the development and testing of novel amphoteric nanosized poly(amidoamine) hydrogel film incorporating 4-aminobutylguanidine (agmatine) moieties to create RGD-mimicking repeating units for promoting cell adhesion. Results A systematic comparative study of the response of an epithelial cell line was performed on hydrogels with agmatine and on non-functionalized amphoteric poly(amidoamine) hydrogels and tissue culture plastic substrates. The cell adhesion on the agmatine containing substrates was comparable to that on plastic substrates and significantly enhanced with respect to the non-functionalized controls. Interestingly, spreading and proliferation on the functionalized supports are slower than on plastic exhibiting the possibility of an easier control of the cell growth kinetics. In order to favor the handling of the samples, a procedure for the production of bi-layered constructs was also developed by means the deposition via spin coating of a thin layer of hydrogel on a pre-treated cover slip. Conclusion The obtained results reveal that PAAs hydrogels can be profitably functionalized and, in general, undergo physical and chemical modifications to meet specific requirements. In particular the incorporation of agmatine warrants good potential in the field of cell culturing and the development of supported functionalized hydrogels on cover glass are very promising substrates for applications in cell screening devices. PMID:19014710

pH- and sugar-sensitive multilayer films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PBA-PAH) and poly(vinyl alcohol) (PVA): A significant effect of PBA content on the film stability.

PubMed

Seno, Masaru; Yoshida, Kentaro; Sato, Katsuhiko; Anzai, Jun-ichi

2016-05-01

Multilayer thin films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PAH), PBA-PAH, with different PBA contents were prepared to study the effect of PBA content on the stability of the films. An alternate deposition of PBA-PAH and poly(vinyl alcohol) (PVA) on the surface of a quartz slide afforded multilayer films through forming boronate ester bonds between PBA-PAH and PVA. The 10-layered (PBA-PAH/PVA)10 films constructed using PBA-PAHs containing 16% and 26% PBA residues were stable in aqueous solutions over the range of pH 4.0-10.0, whereas the multilayer films composed of PBA-PAHs with 5.9% and 8.3% PBA decomposed at pH 8.0 or lower. The pH-sensitive decomposition of the films was rationalized based on the destabilization of the boronate ester bonds in neutral and acidic solutions. In addition, the (PBA-PAH/PVA)10 films decomposed in glucose and fructose solutions as a result of competitive binding of sugars to PBA-PAH in the films. The sugar response of the films depended on the PBA content in PBA-PAH. The (PBA-PAH/PVA)10 films consisting of 16% and 26% PBA-substituted PBA-PAHs are sensitive to physiological relevant level of glucose at pH7.4 while stable in glucose-free solution, suggesting a potential use of the films in constructing glucose-induced delivery systems. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of the side chain and substrate on polythiophene thin film surface, bulk, and buried interfacial structures.

PubMed

Xiao, Minyu; Jasensky, Joshua; Zhang, Xiaoxian; Li, Yaoxin; Pichan, Cayla; Lu, Xiaolin; Chen, Zhan

2016-08-10

The molecular structures of organic semiconducting thin films mediate the performance of various devices composed of such materials. To fully understand how the structures of organic semiconductors alter on substrates due to different polymer side chains and different interfacial interactions, thin films of two kinds of polythiophene derivatives with different side-chains, poly(3-hexylthiophene) (P3HT) and poly(3-potassium-6-hexanoate thiophene) (P3KHT), were deposited and compared on various surfaces. A combination of analytical tools was applied in this research: contact angle goniometry and X-ray photoelectron spectroscopy (XPS) were used to characterize substrate dielectric surfaces with varied hydrophobicity for polymer film deposition; X-ray diffraction and UV-vis spectroscopy were used to examine the polythiophene film bulk structure; sum frequency generation (SFG) vibrational spectroscopy was utilized to probe the molecular structures of polymer film surfaces in air and buried solid/solid interfaces. Both side-chain hydrophobicity and substrate hydrophobicity were found to mediate the crystallinity of the polythiophene film, as well as the orientation of the thiophene ring within the polymer backbone at the buried polymer/substrate interface and the polymer thin film surface in air. For the same type of polythiophene film deposited on different substrates, a more hydrophobic substrate surface induced thiophene ring alignment with the surface normal at both the buried interface and on the surface in air. For different films (P3HT vs. P3KHT) deposited on the same dielectric substrate, a more hydrophobic polythiophene side chain caused the thiophene ring to align more towards the surface at the buried polymer/substrate interface and on the surface in air. We believe that the polythiophene surface, bulk, and buried interfacial molecular structures all influence the hole mobility within the polythiophene film. Successful characterization of an organic conducting thin film surface, buried interfacial, and bulk structures is a first crucial step in understanding the structure-function relationship of such films in order to optimize device performance. An in-depth understanding on how the side-chain influences the interfacial and surface polymer orientation will guide the future molecular structure design of organic semiconductors.

3D printing of hybrid biomaterials for bone tissue engineering: Calcium-polyphosphate microparticles encapsulated by polycaprolactone.

PubMed

Neufurth, Meik; Wang, Xiaohong; Wang, Shunfeng; Steffen, Renate; Ackermann, Maximilian; Haep, Natalie D; Schröder, Heinz C; Müller, Werner E G

2017-12-01

Here we describe the formulation of a morphogenetically active bio-ink consisting of amorphous microparticles (MP) prepared from Ca 2+ and the physiological inorganic polymer, polyphosphate (polyP). Those MP had been fortified by mixing with poly-ε-caprolactone (PCL) to allow 3D-bioprinting. The resulting granular PCL/Ca-polyP-MP hybrid material, liquefied by short-time heating to 100 °C, was used for the 3D-printing of tissue-like scaffolds formed by strands with a thickness of 400 µm and a stacked architecture leaving ≈0.5 mm 2 -sized open holes enabling cell migration. The printed composite scaffold turned out to combine suitable biomechanical properties (Young's modulus of 1.60 ± 0.1 GPa; Martens hardness of 153 ± 28 MPa), matching those of cortical and trabecular bone, with morphogenetic activity. This scaffold was capable of attracting and promoting the growth of human bone-related SaOS-2 cells as demonstrated by staining for cell viability (Calcein AM), cell density (DRAQ5) and SEM studies. Furthermore, the hybrid material was demonstrated to upregulate the steady-state-expression of the cell migration-inducing chemokine SDF-1α. EDX analysis and FTIR measurements revealed the presence of hydroxyapatite in the mineral deposits formed on the scaffold surface. Based on the results we conclude that granular PCL/Ca-polyP-MP hybrid material is suitable for the fabrication of bioprintable scaffold which comprises not only biomechanical stability but also morphogenetic potential. In present-day regenerative engineering efforts, biomaterial- and cell-based strategies are proposed that meet the required functional and spatial characteristics and variations, especially in the transition regions between soft (cartilage, tendon or ligament) and hard (bone) tissues. In a biomimetic approach we succeeded to fabricate amorphous Ca-polyP nanoparticles/microparticles which are highly biocompatible. Together with polycaprolactone (PCL), polyP can be bio-printed. This hybrid material attracts the cells, as documented optically as well as by a gene-expression studies. Since PCL is already a FDA-approved organic and inert polymer and polyP a physiological biologically active component this new bio-hybrid material has the potential to restore physiological functions, including bone remodelling and regeneration if used as implant. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Development of a new class of flexible polymeric membranes for sensing, nanofiltration & cascaded separation

NASA Astrophysics Data System (ADS)

Du, Nian

The last decade has witnessed an explosion of interests in the science and technology of engineered nanomaterials. While the benefits of nanotechnology are widely publicized, the discussion about the transformation of nanomaterials in the environment, and their potential impacts on human health has just begun. Nanoscale particles, whether ultrafine, nano, engineered, intentional, or incidental, pose significant health effects. New approaches for environmental monitoring of nanomaterials at high sensitivity and in real-time are particularly needed. Since nanoparticles must be isolated from complex environmental and biological matrices, the most effective and simple method of isolating engineered nanomaterials from air or water is filtration. Hence the overall project objective of this work is to develop innovative methods that can simultaneously remove, detect and inactivate diverse nanostructured materials. At the center of the technology is a novel class of polymeric filters capable of simultaneously removing and detecting metal and metal oxide nanoparticles. This project reports the development of a new class of self-standing, flexible, phase-inverted, poly(amic) acid membranes with experimentally-controlled nanopores ranging from less than 10nm to greater than 100nm. Compared to most commercial filter membranes, phase-inverted PAA membranes were found to exhibit superior durability and higher efficiency. The filtration efficiency was ˜99.97% for a number of nanoparticles including Quantum Dots, TiO2, Au and Ag. This work also showed that PAA membranes could be used to separate mixtures of nanoparticles. Although the separation does not show much selectivity according to the NPs’ chemical composition, it shows the ability to separate efficiently based on nanoparticle size. PAA showed an excellent performance not only for nanoparticle isolation at sub-nanometer size ranges, but also as a platform for the detection of engineered nanoparticles at low ppb levels. We demonstrated the application of phase-inverted PAA membranes for quantitative detection of silver NPs using commercial food supplements, and the results were confirmed with AAS, SEM and EDS. Selective detection was achieved in the presence of high concentrations of other metal nanoparticles such as zinc oxide and gold NPs, and silver ions.

Preparation and properties of in situ amino-functionalized graphene oxide/polyimide composite films

NASA Astrophysics Data System (ADS)

Lu, Yunhua; Hao, Jican; Xiao, Guoyong; Chen, Lin; Wang, Tonghua; Hu, Zhizhi

2017-11-01

The pure light-colored and transparent polyimide (PI) film was prepared from aromatic dianhydride 4,4‧-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and diamine 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) in the solvent of DMAc via two-step method. Graphene oxide (GO) was in situ grafted with 6FAPB and directly used as a functional inorganic nanofiller to further synthesize poly(amic acid) (PAA)/GO solution. Then, PI/GO composite films with different loadings of GO were prepared by the thermal imidization. The mechanical, thermal, optical, electrical, surface properties, and electrochemical behavior were characterized. The FTIR and XPS results indicate that amino groups can be successfully grafted on the surface of GO. The tensile strength and Young's modulus of the PI-1.0%GO composite film were increased to 118.4 MPa and 2.91 GPa, respectively, which was an approximate improvement of 30.8% and 39.9% compared with pure PI film. These PI/GO composites showed around 256 °C for the glass transition temperature, and around 535 °C for the 5% thermal decomposition temperature, respectively. However, the optical transmittance was significantly decreased from 81.5% (pure PI) to 0.8% (PI-1.0%GO). Besides, the electrical conductivity increased from 1.6 × 10-13 S/m (pure PI) to 2.5 × 10-9 S/m (PI-1.0%GO). Furthermore, when the incorporation of GO was 1.0 wt%, an obvious reduction from 1.08% (pure PI) to 0.65% in the water uptake was observed for the PI/GO composite films, and the water surface contact angle raised from 72.5° (pure PI) to 83.5°. The electrochemical behavior showed that the ability of oxygen atom on the imide ring to gain and loss electron was increased due to incorporation of GO. These results indicated that the strong interfacial interaction between GO and PAA as well as uniform dispersion of GO in PI matrix were benefit to improve the mechanical, thermal, electrical properties and so on. The in situ amino-functionalized approach provides a strategy for preparing high-performance PI-based composite materials.

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.

Advanced thermoplastic resins, phase 1

NASA Technical Reports Server (NTRS)

Hendricks, C. L.; Hill, S. G.; Falcone, A.; Gerken, N. T.

1991-01-01

Eight thermoplastic polyimide resin systems were evaluated as composite matrix materials. Two resins were selected for more extensive mechanical testing and both were versions of LaRC-TPI (Langley Research Center - Thermoplastic Polyimide). One resin was made with LaRC-TPI and contained 2 weight percent of a di(amic acid) dopant as a melt flow aid. The second system was a 1:1 slurry of semicrystalline LaRC-TPI powder in a polyimidesulfone resin diglyme solution. The LaRC-TPI powder melts during processing and increases the melt flow of the resin. Testing included dynamic mechanical analysis, tension and compression testing, and compression-after-impact testing. The test results demonstrated that the LaRC-TPI resins have very good properties compared to other thermoplastics, and that they are promising matrix materials for advanced composite structures.

[Current overview of cartilage regeneration procedures].

PubMed

Schenker, H; Wild, M; Rath, B; Tingart, M; Driessen, A; Quack, V; Betsch, M

2017-11-01

Cartilage is an avascular, alymphatic and non-innervated tissue with limited intrinsic repair potential. The high prevalence of cartilage defects and their tremendous clinical importance are a challenge for all treating physicians. This article provides the reader with an overview about current cartilage treatment options and their clinical outcome. Microfracture is still considered the gold standard in the treatment of small cartilage lesions. Small osteochondral defects can be effectively treated with the autologous osteochondral transplantation system. Larger cartilage defects are successfully treated by autologous membrane-induced chondrogenesis (AMIC) or by membrane-assisted autologous chondrocyte implantation (MACI). Despite limitations of current cartilage repair strategies, such procedures can result in short- and mid-term clinical improvement of the patients. Further developments and clinical studies are necessary to improve the long-term outcome following cartilage repair.

Electromagnetically induced grating with Rydberg atoms

NASA Astrophysics Data System (ADS)

Asghar, Sobia; Ziauddin, Qamar, Shahid; Qamar, Sajid

2016-09-01

We present a scheme to realize electromagnetically induced grating in an ensemble of strongly interacting Rydberg atoms, which act as superatoms due to the dipole blockade mechanism. The ensemble of three-level cold Rydberg-dressed (87Rb) atoms follows a cascade configuration where a strong standing-wave control field and a weak probe pulse are employed. The diffraction intensity is influenced by the strength of the probe intensity, the control field strength, and the van der Waals (vdW) interaction. It is noticed that relatively large first-order diffraction can be obtained for low-input intensity with a small vdW shift and a strong control field. The scheme can be considered as an amicable solution to realize the atomic grating at the microscopic level, which can provide background- and dark-current-free diffraction.

Older Parent – Child Relationships in Six Developed Nations: Comparisons at the Intersection of Affection and Conflict

PubMed Central

Silverstein, Merril; Gans, Daphna; Lowenstein, Ariela; Giarrusso, Roseann; Bengtson, Vern L.

2014-01-01

Intergenerational solidarity and ambivalence paradigms suggest that emotional relationships between generations consist of both positive and negative sentiments. We applied latent class analysis to measures of affection and conflict in 2,698 older parent – child relationships in 6 developed nations: England, Germany, Israel, Norway, Spain, and the United States (Southern California). The best fitting model consisted of 4 latent classes distributed differently across nations but with a cross-nationally invariant measurement structure. After controlling for demographics, health, coresidence, contact, and support, the following classes were overrepresented in corresponding nations: amicable (England), detached (Germany and Spain), disharmonious (United States), ambivalent (Israel). We discuss policy and cultural differences across societies that may explain why the prevalence of particular emotional types varied by nation. PMID:26203197

Older Parent - Child Relationships in Six Developed Nations: Comparisons at the Intersection of Affection and Conflict.

PubMed

Silverstein, Merril; Gans, Daphna; Lowenstein, Ariela; Giarrusso, Roseann; Bengtson, Vern L

2010-08-01

Intergenerational solidarity and ambivalence paradigms suggest that emotional relationships between generations consist of both positive and negative sentiments. We applied latent class analysis to measures of affection and conflict in 2,698 older parent - child relationships in 6 developed nations: England, Germany, Israel, Norway, Spain, and the United States (Southern California). The best fitting model consisted of 4 latent classes distributed differently across nations but with a cross-nationally invariant measurement structure. After controlling for demographics, health, coresidence, contact, and support, the following classes were overrepresented in corresponding nations: amicable (England), detached (Germany and Spain), disharmonious (United States), ambivalent (Israel). We discuss policy and cultural differences across societies that may explain why the prevalence of particular emotional types varied by nation.

Quantitative control of poly(ethylene oxide) surface antifouling and biodetection through azimuthally enhanced grating coupled-surface plasmon resonance sensing

NASA Astrophysics Data System (ADS)

Sonato, Agnese; Silvestri, Davide; Ruffato, Gianluca; Zacco, Gabriele; Romanato, Filippo; Morpurgo, Margherita

2013-12-01

Grating Coupled-Surface Plasmon reflectivity measurements carried out under azimuth and polarization control (GC-SPR φ ≠ 0°) were used to optimize the process of gold surface dressing with poly(ethylene oxide) (PEO) derivatives of different molecular weight, with the final goal to maximize the discrimination between specific and non-specific binding events occurring at the surface. The kinetics of surface deposition of thiol-ending PEOs (0.3, 2 and 5 kDa), introduced as antifouling layers, was monitored. Non-specific binding events upon immersion of the surfaces into buffers containing either 0.1% bovine serum albumin or 1% Goat Serum, were evaluated as a function of polymer size and density. A biorecognition event between avidin and biotin was then monitored in both buffers at selected low and high polymer surface densities and the contribution of analyte and fouling elements to the signal was precisely quantified. The 0.3 kDa PEO film was unable to protect the surface from non-specific interactions at any tested density. On the other hand, the 2 and 5 kDa polymers at their highest surface densities guaranteed full protection from non-specific interactions from both buffers. These densities were reached upon a long deposition time (24-30 h). The results pave the way toward the application of this platform for the detection of low concentration and small dimension analytes, for which both non-fouling and high instrumental sensitivity are fundamental requirements.

Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles

NASA Astrophysics Data System (ADS)

Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

2016-09-01

We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT-Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT-Fe3O4 concentration is approximately 33 vol.%. The BT-Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10-9 S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT-Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT-Fe3O4 hybrid particles. However, the experimental results of the BT-Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT-Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry.

3D fiber deposited polymeric scaffolds for external auditory canal wall.

PubMed

Mota, Carlos; Milazzo, Mario; Panetta, Daniele; Trombi, Luisa; Gramigna, Vera; Salvadori, Piero A; Giannotti, Stefano; Bruschini, Luca; Stefanini, Cesare; Moroni, Lorenzo; Berrettini, Stefano; Danti, Serena

2018-05-07

The external auditory canal (EAC) is an osseocartilaginous structure extending from the auricle to the eardrum, which can be affected by congenital, inflammatory, and neoplastic diseases, thus reconstructive materials are needed. Current biomaterial-based approaches for the surgical reconstruction of EAC posterior wall still suffer from resorption (biological) and extrusion (synthetic). In this study, 3D fiber deposited scaffolds based on poly(ethylene oxide terephthalate)/poly(butylene terephthalate) were designed and fabricated to replace the EAC wall. Fiber diameter and scaffold porosity were optimized, leading to 200 ± 33 µm and 55% ± 5%, respectively. The mechanical properties were evaluated, resulting in a Young's modulus of 25.1 ± 7.0 MPa. Finally, the EAC scaffolds were tested in vitro with osteo-differentiated human mesenchymal stromal cells (hMSCs) with different seeding methods to produce homogeneously colonized replacements of interest for otologic surgery. This study demonstrated the fabrication feasibility of EAC wall scaffolds aimed to match several important requirements for biomaterial application to the ear under the Tissue Engineering paradigm, including shape, porosity, surface area, mechanical properties and favorable in vitro interaction with osteoinduced hMSCs. This study demonstrated the fabrication feasibility of outer ear canal wall scaffolds via additive manufacturing. Aimed to match several important requirements for biomaterial application to ear replacements under the Tissue Engineering paradigm, including shape, porosity and pore size, surface area, mechanical properties and favorable in vitro interaction with osteo-differentiated mesenchymal stromal cells.

Poly-(R)-3-hydroxybutyrates (PHB) are Atherogenic Components of Lipoprotein Lp(a).

PubMed

Reusch, Rosetta N

2015-12-01

The hypothesis is that poly-(R)-3-hydroxybutyrates (PHB), linear polymers of the ketone body, R-3-hydroxybutyrate (R-3HB), are atherogenic components of lipoprotein Lp(a). PHB are universal constituents of biological cells and are thus components of all foods. Medium chain-length PHB (<200 residues) (mPHB) are located in membranes and organelles, and short-chain PHB (<15 residues) are covalently attached to certain proteins (cPHB). PHB are highly insoluble in water, but soluble in lipids in which they exhibit a high intrinsic viscosity. They have a higher density than other cellular lipids and they are very adhesive, i.e. they engage in multiple noncovalent interactions with other molecules and salts via hydrogen, hydrophobic and coordinate bonds, thus producing insoluble deposits. Following digestive processes, PHB enter the circulation in chylomicrons and very low density lipoproteins (VLDL). The majority of the PHB (>70%) are absorbed by albumin, which transports them to the liver for disposal. When the amount of PHB in the diet exceed the capacity of albumin to safely remove them from the circulation, the excess PHB remain in the lipid core of LDL particles that become constituents of lipoprotein Lp(a), and contribute to the formation of arterial deposits. In summary, the presence of PHB – water-insoluble, dense, viscous, adhesive polymers – in the lipid cores of the LDL moieties of Lp(a) particles supports the hypothesis that PHB are atherogenic components of Lp(a).

An in-line Mach-Zehnder Interferometer Using Thin-core Fiber for Ammonia Gas Sensing With High Sensitivity

PubMed Central

Huang, Xinyue; Li, Xueming; Yang, Jianchun; Tao, Chuanyi; Guo, Xiaogang; Bao, Hebin; Yin, Yanjun; Chen, Huifei; Zhu, Yuhua

2017-01-01

Ammonia is an important indicator among environmental monitoring parameters. In this work, thin-core fiber Mach-Zehnder interferometer deposited with poly (acrylic acid) (PAA), poly (allyamine hydrochloride) (PAH) and single-walled carbon nanotubes (SWCNTs-COOH) sensing film for the detection of ammonia gas has been presented. The thin-core fiber modal interferometer was made by fusion splicing a small section of thin-core fiber (TCF) between two standard single mode fibers (SMF). A beam propagation method (BPM) is employed for the design of proposed interferometer and numerical simulation. Based on the simulation results, interferometer with a length of 2 cm of thin-core fiber is fabricated and experimentally studied. (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film is deposited on the outer surface of thin-core fiber via layer-by-layer (LbL) self-assembly technique. The gas sensor coated with (PAH/PAA)2 + [PAH/(PAA + SWCNTs-COOH)]8 film towards NH3 gas exposure at concentrations range from 1 to 960 ppm are analyzed and the sensing capability is demonstrated by optical spectrum analyzer (OSA). Experimental results show that the characteristic wavelength shift has an approximately linear relationship in the range 1–20 ppm, which is in accordance with the numerical simulation. Thus, this paper reveals the potential application of this sensor in monitoring low concentration NH3 gas. PMID:28378783

MC3T3-E1 Cell Response to Ti1-xAgx and Ag-TiNx Electrodes Deposited on Piezoelectric Poly(vinylidene fluoride) Substrates for Sensor Applications.

PubMed

Marques, S M; Rico, P; Carvalho, I; Gómez Ribelles, J L; Fialho, L; Lanceros-Méndez, S; Henriques, M; Carvalho, S

2016-02-17

In the sensors field, titanium based coatings are being used for the acquisition/application of electrical signals from/to piezoelectric materials. In this particular case, sensors are used to detect dynamic mechanical loads at early stages after intervention of problems associated with prostheses implantation. The aim of this work is to select an adequate electrode for sensor applications capable, in an initial stage to avoid bone cell adhesion, but at a long stage, permit osteointegration and osteoinduction. This work reports on the evaluation of osteoblast MC3T3-E1 cells behavior in terms of proliferation, adhesion and long-term differentiation of two different systems used as sensor electrodes: Ti1-xAgx and Ag-TiNx deposited by d.c. and pulsed magnetron sputtering at room temperature on poly(vinylidene fluoride) (PVDF). The results indicated an improved effect of Ag-TiNx electrodes compared with Ti1-xAgx and TiN, in terms of diminished cell adhesion and proliferation at an initial cell culture stage. Nevertheless, when cell culture time is longer, cells grown onto Ag-TiNx electrodes are capable to proliferate and also differentiate at proper rates, indicating the suitability of this coating for sensor application in prostheses devices. Thus, the Ag-TiNx system was considered the most promising electrode for tissue engineering applications in the design of sensors for prostheses to detect dynamic mechanical loads.

Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles.

PubMed

Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

2016-09-16

We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT-Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT-Fe3O4 concentration is approximately 33 vol.%. The BT-Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10(-9) S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT-Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT-Fe3O4 hybrid particles. However, the experimental results of the BT-Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT-Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry.

Enhanced dielectric properties of poly(vinylidene fluoride) composites filled with nano iron oxide-deposited barium titanate hybrid particles

PubMed Central

Zhang, Changhai; Chi, Qingguo; Dong, Jiufeng; Cui, Yang; Wang, Xuan; Liu, Lizhu; Lei, Qingquan

2016-01-01

We report enhancement of the dielectric permittivity of poly(vinylidene fluoride) (PVDF) generated by depositing magnetic iron oxide (Fe3O4) nanoparticles on the surface of barium titanate (BT) to fabricate BT–Fe3O4/PVDF composites. This process introduced an external magnetic field and the influences of external magnetic field on dielectric properties of composites were investigated systematically. The composites subjected to magnetic field treatment for 30 min at 60 °C exhibited the largest dielectric permittivity (385 at 100 Hz) when the BT–Fe3O4 concentration is approximately 33 vol.%. The BT–Fe3O4 suppressed the formation of a conducting path in the composite and induced low dielectric loss (0.3) and low conductivity (4.12 × 10−9 S/cm) in the composite. Series-parallel model suggested that the enhanced dielectric permittivity of BT–Fe3O4/PVDF composites should arise from the ultrahigh permittivity of BT–Fe3O4 hybrid particles. However, the experimental results of the BT–Fe3O4/PVDF composites treated by magnetic field agree with percolation theory, which indicates that the enhanced dielectric properties of the BT–Fe3O4/PVDF composites originate from the interfacial polarization induced by the external magnetic field. This work provides a simple and effective way for preparing nanocomposites with enhanced dielectric properties for use in the electronics industry. PMID:27633958

A fast flexible ink-jet printing method for patterning dissociated neurons in culture.

PubMed

Sanjana, Neville E; Fuller, Sawyer B

2004-07-30

We present a new technique that uses a custom-built ink-jet printer to fabricate precise micropatterns of cell adhesion materials for neural cell culture. Other work in neural cell patterning has employed photolithography or "soft lithographic" techniques such as micro-stamping, but such approaches are limited by their use of an un-alterable master pattern such as a mask or stamp master and can be resource-intensive. In contrast, ink-jet printing, used in low-cost desktop printers, patterns material by depositing microscopic droplets under robotic control in a programmable and inexpensive manner. We report the use of ink-jet printing to fabricate neuron-adhesive patterns such as islands and other shapes using poly(ethylene) glycol as the cell-repulsive material and a collagen/poly-D-lysine (PDL) mixture as the cell-adhesive material. We show that dissociated rat hippocampal neurons and glia grown at low densities on such patterns retain strong pattern adherence for over 25 days. The patterned neurons are comparable to control, un-patterned cells in electrophysiological properties and in immunocytochemical measurements of synaptic density and inhibitory cell distributions. We suggest that an inexpensive desktop printer may be an accessible tool for making micro-island cultures and other basic patterns. We also suggest that ink-jet printing may be extended to a range of developmental neuroscience studies, given its ability to more easily layer materials, build substrate-bound gradients, construct out-of-plane structure, and deposit sources of diffusible factors. Copyright 2004 Elsevier B.V.

Time-Resolved Study of Nanomorphology and Nanomechanic Change of Early-Stage Mineralized Electrospun Poly(lactic acid) Fiber by Scanning Electron Microscopy, Raman Spectroscopy and Atomic Force Microscopy

PubMed Central

Wang, Mengmeng; Cai, Yin; Zhao, Bo; Zhu, Peizhi

2017-01-01

In this study, scanning electron microscopy (SEM), Raman spectroscopy and high-resolution atomic force microscopy (AFM) were used to reveal the early-stage change of nanomorphology and nanomechanical properties of poly(lactic acid) (PLA) fibers in a time-resolved manner during the mineralization process. Electrospun PLA nanofibers were soaked in simulated body fluid (SBF) for different periods of time (0, 1, 3, 5, 7 and 21 days) at 10 °C, much lower than the conventional 37 °C, to simulate the slow biomineralization process. Time-resolved Raman spectroscopy analysis can confirm that apatites were deposited on PLA nanofibers after 21 days of mineralization. However, there is no significant signal change among several Raman spectra before 21 days. SEM images can reveal the mineral deposit on PLA nanofibers during the process of mineralization. In this work, for the first time, time-resolved AFM was used to monitor early-stage nanomorphology and nanomechanical changes of PLA nanofibers. The Surface Roughness and Young’s Modulus of the PLA nanofiber quantitatively increased with the time of mineralization. The electrospun PLA nanofibers with delicate porous structure could mimic the extracellular matrix (ECM) and serve as a model to study the early-stage mineralization. Tested by the mode of PLA nanofibers, we demonstrated that AFM technique could be developed as a potential diagnostic tool to monitor the early onset of pathologic mineralization of soft tissues. PMID:28817096

Effects of surface tension and viscosity on gold and silver sputtered onto liquid substrates

NASA Astrophysics Data System (ADS)

De Luna, Mark M.; Gupta, Malancha

2018-05-01

In this paper, we study DC magnetron sputtering of gold and silver onto liquid substrates of varying viscosities and surface tensions. We were able to separate the effects of viscosity from surface tension by depositing the metals onto silicone oils with a range of viscosities. The effects of surface tension were studied by depositing the metals onto squalene, poly(ethylene glycol), and glycerol. It was found that dispersed nanoparticles were formed on liquids with low surface tension and low viscosity whereas dense films were formed on liquids with low surface tension and high viscosity. Nanoparticles were formed on both the liquid surface and within the bulk liquid for high surface tension liquids. Our results can be used to tailor the metal and liquid interaction to fabricate particles and films for various applications in optics, electronics, and catalysis.

Electrical properties of solution processed highly transparent ZnO TFT with organic gate dielectric

NASA Astrophysics Data System (ADS)

Pandya, Nirav C.; Joshi, Nikhil G.; Trivedi, U. N.; Joshi, U. S.

2013-02-01

All oxide thin film transistors (TFT) with zinc oxide active layer were fabricated by chemical solution deposition (CSD) using aqueous solutions on glass substrate. Thin film transistors (TFTs) with amorphous zinc oxide as channel layers and poly-vinyl alcohol as dielectric layers were fabricated at low temperatures by chemical solution deposition (CSD). Atomic force microscopy (AFM) confirmed nano grain size with fairly smooth surface topography. Very small leakage currents were achieved in the transfer curves, while soft saturation was observed in the output current voltage (I-V) characteristics of the device. Optical transmission of better than 87% in the visible region was estimated, which is better than the organic gate insulator based ZnO TFTs reported so far. Our results offer lot of promise to TFT based display and optoelectronics.

Construction of protein-resistant pOEGMA films by helicon plasma-enhanced chemical vapor deposition.

PubMed

Lee, Bong Soo; Yoon, Ok Ja; Cho, Woo Kyung; Lee, Nae-Eung; Yoon, Kuk Ro; Choi, Insung S

2009-01-01

This paper describes the formation of protein-resistant, poly(ethylene glycol) methyl ether methacrylate (pOEGMA) thin films by helicon plasma-enhanced chemical vapor deposition (helicon-PECVD). pOEGMA was successfully grafted onto a silicon substrate, as a model substrate, without any additional surface initiators, by plasma polymerization of OEGMA. The resulting pOEGMA films were characterized by ellipsometry, FT-IR spectroscopy, X-ray photoelectron spectroscopy and contact angle goniometry. To investigate the protein-resistant property of the pOEGMA films, four different proteins, bovine serum albumin, fibrinogen, lysozyme and ribonuclease A, were tested as model proteins for ellipsometric measurements. The ellipsometric thickness change for all the model proteins was less than 3 A, indicating that the formed pOEGMA films are protein-resistant. (c) Koninklijke Brill NV, Leiden, 2009

Interaction of metal layers with polycrystalline Si

NASA Technical Reports Server (NTRS)

Nakamura, K.; Olowolafe, J. O.; Lau, S. S.; Nicolet, M.-A.; Mayer, J. W.; Shima, R.

1976-01-01

Solid-phase reactions of metal films deposited on 0.5-micron-thick polycrystalline layers of Si grown by chemical vapor deposition at 640 C were investigated by MeV He-4 backscattering spectrometry, glancing angle X-ray diffraction, and SEM observations. For the metals Al, Ag, and Au, which form simple eutectics, heat treatment at temperatures below the eutectic results in erosion of the poly-Si layer and growth of Si crystallites in the metal film. Crystallite formation is observed at temperatures exceeding 550 C for Ag, at those exceeding 400 C for Al, and at those exceeding 200 C for Au films. For Pd, Ni, and Cr, heat treatment results in silicide formation. The same initial silicides (Pd2Si, Ni2Si, and CrSi2), are formed at similar temperatures on single-crystal substrates.

Mechanical Properties Optimization of Poly-Ether-Ether-Ketone via Fused Deposition Modeling.

PubMed

Deng, Xiaohu; Zeng, Zhi; Peng, Bei; Yan, Shuo; Ke, Wenchao

2018-01-30

Compared to the common selective laser sintering (SLS) manufacturing method, fused deposition modeling (FDM) seems to be an economical and efficient three-dimensional (3D) printing method for high temperature polymer materials in medical applications. In this work, a customized FDM system was developed for polyether-ether-ketone (PEEK) materials printing. The effects of printing speed, layer thickness, printing temperature and filling ratio on tensile properties were analyzed by the orthogonal test of four factors and three levels. Optimal tensile properties of the PEEK specimens were observed at a printing speed of 60 mm/s, layer thickness of 0.2 mm, temperature of 370 °C and filling ratio of 40%. Furthermore, the impact and bending tests were conducted under optimized conditions and the results demonstrated that the printed PEEK specimens have appropriate mechanical properties.

Perovskite solar cells based on nanocolumnar plasma-deposited ZnO thin films.

PubMed

Ramos, F Javier; López-Santos, Maria C; Guillén, Elena; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Gonzalez-Elipe, Agustin R; Ahmad, Shahzada

2014-04-14

ZnO thin films having a nanocolumnar microstructure are grown by plasma-enhanced chemical vapor deposition at 423 K on pre-treated fluorine-doped tin oxide (FTO) substrates. The films consist of c-axis-oriented wurtzite ZnO nanocolumns with well-defined microstructure and crystallinity. By sensitizing CH3NH3PbI3 on these photoanodes a power conversion of 4.8% is obtained for solid-state solar cells. Poly(triarylamine) is found to be less effective when used as the hole-transport material, compared to 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene (spiro-OMeTAD), while the higher annealing temperature of the perovskite leads to a better infiltration in the nanocolumnar structure and an enhancement of the cell efficiency. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Deposit heterogeneity and the dynamics of the organic semiconductors P3HT and PCBM solution under evaporation

NASA Astrophysics Data System (ADS)

Yu, H. P.; Luo, H.; Liu, T. T.; Jing, G. Y.

2015-04-01

The formation of organic semiconductor layer is the key procedure in the manufacture of organic photovoltaic solar cell, in which the natural evaporation of the solvent from the polymer solution plays the essential role for the conversion efficiency. Here, poly(3-hexylthiophene) (P3HT) and fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), as two types of semiconductor polymers, were selected as the active layer to form the deposit by drying the blend solution drops on the substrate. We explored the influences of droplet size and solute concentration on the homogeneity of the deposit. Additionally, the spatial distribution of molecular chains and grains and the instability of the droplet morphology during the drying were investigated. The results showed that the "coffee-ring" phenomenon occurred forming an annular deposit at the outermost edge and the width of the annular ring increased linearly with the concentration of the P3HT solution, until a saturation plateau is approached. On the other hand, the PCBM deposition presented a circular disk at low concentration, but displayed a sudden instability for an irregular perimeter at a critical concentration and there existed a second critical concentration above which the deposit exhibited the return of the stable circular shape. The results have an instructive impact on the performance of the device and the formation of fine structures during the process of printing, film preparation and painting.

Drying temperature effects on electrical and optical properties of poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film

NASA Astrophysics Data System (ADS)

Azhar, N. E. A.; Affendi, I. H. H.; Shafura, A. K.; Shariffudin, S. S.; Alrokayan, Salman A. H.; Khan, Haseeb A.; Rusop, M.

2016-07-01

Temperature effects on electrical and optical properties of a representative semiconducting polymer, poly[2-methoxy-5-(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), has recently attracted much attention. The MEH-PPV thin films were deposited at different drying temperature (anneal temperature) using spin-coating technique. The spin coating technique was used to produce uniform film onto large area. The MEH-PPV was dissolved in toluene solution to exhibits different optical and electrical properties. The absorption coefficient and bandgap was measured using UV-Visible-NIR (UV-VIS-NIR). The bandgap of MEH-PPV was effect by the thickness of thin films. For electrical properties, two-point probe was used to characterize the current-voltage measurement. The current-voltage measurement shows that the MEH-PPV thin films become more conductive at high temperature. This study will provide better performance and suitable for optoelectronic device especially OLEDs applications.

Neutral Poly-/perfluoroalkyl Substances in Air and Snow from the Arctic

PubMed Central

Xie, Zhiyong; Wang, Zhen; Mi, Wenying; Möller, Axel; Wolschke, Hendrik; Ebinghaus, Ralf

2015-01-01

Levels of neutral poly-/perfluoroalkyl substances (nPFASs) in air and snow collected from Ny-Ålesund were measured and their air-snow exchange was determined to investigate whether they could re-volatilize into the atmosphere driven by means of air-snow exchange. The total concentration of 12 neutral PFASs ranged from 6.7 to 39 pg m−3 in air and from 330 to 690 pg L−1 in snow. A significant log-linear relationship was observed between the gas/particle partition coefficient and vapor pressure of the neutral PFASs. For fluorotelomer alcohol (FTOHs) and fluorotelomer acrylates (FTAs), the air-snow exchange fluxes were positive, indicating net evaporative from snow into air, while net deposition into snow was observed for perfluorooctane sulfonamidoethanols (Me/EtFOSEs) in winter and spring of 2012. The air-snow exchange was snow-phase controlled for FTOHs and FTAs, and controlled by the air-phase for FOSEs. Air-snow exchange may significantly interfere with atmospheric concentrations of neutral PFASs in the Arctic. PMID:25746440

Drying temperature effects on electrical and optical properties of poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin film

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

Azhar, N. E. A., E-mail: najwaezira@yahoo.com; Affendi, I. H. H., E-mail: irmahidayanti.halim@gmail.com; Shafura, A. K., E-mail: shafura@ymail.com

Temperature effects on electrical and optical properties of a representative semiconducting polymer, poly[2-methoxy-5-(2’-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV), has recently attracted much attention. The MEH-PPV thin films were deposited at different drying temperature (anneal temperature) using spin-coating technique. The spin coating technique was used to produce uniform film onto large area. The MEH-PPV was dissolved in toluene solution to exhibits different optical and electrical properties. The absorption coefficient and bandgap was measured using UV-Visible-NIR (UV-VIS-NIR). The bandgap of MEH-PPV was effect by the thickness of thin films. For electrical properties, two-point probe was used to characterize the current-voltage measurement. The current-voltage measurement showsmore » that the MEH-PPV thin films become more conductive at high temperature. This study will provide better performance and suitable for optoelectronic device especially OLEDs applications.« less

Gold nanoparticles stabilized by poly(4-vinylpyridine) grafted cellulose nanocrystals as efficient and recyclable catalysts.

PubMed

Zhang, Zhen; Sèbe, Gilles; Wang, Xiaosong; Tam, Kam C

2018-02-15

pH-responsive poly(4-vinylpyridine) (P4VP) grafted cellulose nanocrystals (P4VP-g-CNC) were prepared by Surface-Initiated Atom Transfer Radical Polymerization (SI-ATRP) and subsequently used to stabilize gold nanoparticles (Au NPs) as efficient and recyclable nanocatalysts for the reduction of 4-nitrophenol (4NP). The presence of P4VP brushes on the CNC surface controlled the growth of Au NPs yielding smaller averaged diameter compared to Au NPs deposited directly on pristine CNC. The catalytic performances of pristine Au NPs, Au@CNC and Au@P4VP-g-CNC were compared by measuring the turnover frequency (TOF) for the catalytic reduction of 4NP. Compared to pristine Au NPs, the catalytic activity of Au@CNC and Au@P4VP-g-CNC were 10 and 24 times better. Moreover, the Au@P4VP-g-CNC material could be recovered via flocculation at pH>5, and the recycled nanocatalyst remained highly active. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fabrication of high quality carbonaceous coating on Cu nanoparticle using poly(vinyl pyrrolidone) and its application for oxidation prevention

NASA Astrophysics Data System (ADS)

Pyo, Youngjun; Choi, Dahyun; Son, Yeon-Ho; Kang, Suhee; Yoon, Eric H.; Jung, Seung-Boo; Kim, Yongil; Sunyong Lee, Caroline

2016-05-01

A novel method of carbonaceous coating on the surface of copper particles was developed through a chemical vapor deposition (CVD) process to prevent the oxidation of copper nanoparticles (CNPs). The types of poly(vinyl pyrrolidone) (PVP) used were K-12 (M W 3,500) and K-30 (M W 45,000). The amounts of PVP used ranged from 10 to 50 wt %. Additionally, processing temperatures of 900 and 875 °C were tested and compared. The optimum CVD process conditions for the carbonaceous coating were as follows: 875 °C processing temperature, 50 wt % K12 PVP solution, and gas conditions of \\text{Ar}:\\text{H}2 = 1:1. The resistivity change in the fabricated copper pattern was confirmed that the initial resistivity value of the ink with a mixing ratio of carbonaceous-coated CNPs to 1-octanethiol-coated CNPs of 4:6 (w/w) maintained its initial resistivity value of 2.93 × 10-7 Ω·m for more than 210 days.

Non-Fouling Biodegradable Poly(ϵ-caprolactone) Nanofibers for Tissue Engineering.

PubMed

Kostina, Nina Yu; Pop-Georgievski, Ognen; Bachmann, Michael; Neykova, Neda; Bruns, Michael; Michálek, Jiří; Bastmeyer, Martin; Rodriguez-Emmenegger, Cesar

2016-01-01

Poly(ϵ-caprolactone) (PCL) nanofibers are very attractive materials for tissue engineering (TE) due to their degradability and structural similarity to the extracellular matrix (ECM). However, upon exposure to biological media, their surface is rapidly fouled by proteins and cells, which may lead to inflammation and foreign body reaction. In this study, an approach for the modification of PCL nanofibers to prevent protein fouling from biological fluids and subsequent cell adhesion is introduced. A biomimetic polydopamine (PDA) layer was deposited on the surface of the PCL nanofibers and four types of antifouling polymer brushes were grown by surface-initiated atom transfer radical polymerization (SI-ATRP) from initiator moieties covalently attached to the PDA layer. Cell adhesion was assessed with mouse embryonic fibroblasts (MEFs). MEFs rapidly adhered and formed cell-matrix adhesions (CMAs) with PCL and PCL-PDA nanofibers. Importantly, the nanofibers modified with antifouling polymer brushes were able to suppress non-specific protein adsorption and thereby cell adhesion. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

pH and Glucose Dual-Responsive Injectable Hydrogels with Insulin and Fibroblasts as Bioactive Dressings for Diabetic Wound Healing.

PubMed

Zhao, Lingling; Niu, Lijing; Liang, Hongze; Tan, Hui; Liu, Chaozong; Zhu, Feiyan

2017-11-01

pH and glucose dual-responsive injectable hydrogels were prepared through the cross-linking of Schiff's base and phenylboronate ester using phenylboronic-modified chitosan, poly(vinyl alcohol) and benzaldehyde-capped poly(ethylene glycol). Protein drugs and live cells could be incorporated into the hydrogels during the in situ cross-linking, displaying sustained and pH/glucose-triggered drug release from the hydrogels and cell viability and proliferation in the three-dimensional hydrogel matrix as well. Hence, the hydrogels with insulin and fibroblasts were considered as bioactive dressings for diabetic wound healing. A streptozotocin-induced diabetic rat model was used to evaluate the efficacy of hydrogel dressings in wound repair. The results revealed that the incorporation of insulin and L929 in the hydrogels could promote neovascularization and collagen deposition and enhance the wound-healing process of diabetic wounds. Thus, the drug- and cell-loaded hydrogels have promising potential in wound healing as a medicated system for various therapeutic proteins and live cells.

Poly(methyl methacrylate) as a self-assembled gate dielectric for graphene field-effect transistors

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

Sanne, A.; Movva, H. C. P.; Kang, S.

We investigate poly(methyl methacrylate) (PMMA) as a low thermal budget organic gate dielectric for graphene field effect-transistors (GFETs) based on a simple process flow. We show that high temperature baking steps above the glass transition temperature (∼130 °C) can leave a self-assembled, thin PMMA film on graphene, where we get a gate dielectric almost for “free” without additional atomic layer deposition type steps. Electrical characterization of GFETs with PMMA as a gate dielectric yields a dielectric constant of k = 3.0. GFETs with thinner PMMA dielectrics have a lower dielectric constant due to decreased polarization arising from neutralization of dipoles and charged carriersmore » as baking temperatures increase. The leakage through PMMA gate dielectric increases with decreasing dielectric thickness and increasing electric field. Unlike conventional high-k gate dielectrics, such low-k organic gate dielectrics are potentially attractive for devices such as the proposed Bilayer pseudoSpin Field-Effect Transistor or flexible high speed graphene electronics.« less

Differentiation of bone marrow stromal cells in poly(lactide-co-glycolide)/chitosan scaffolds.

PubMed

Kuo, Yung-Chih; Yeh, Chun-Fu; Yang, Jen-Tsung

2009-12-01

This study investigates the physicochemical properties of poly(lactide-co-glycolide) (PLGA)/chitosan scaffolds and the neuron growth factor (NGF)-guided differentiation of bone marrow stromal cells (BMSCs) in the scaffolds. The scaffolds were prepared by the crosslinking of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide and genipin, and the differentiating BMSCs were characterized against CD44, CD90 and NeuN. The scaffold with 20% PLGA yielded 95% porosity, Young's modulus of 13MPa, 70% adhesion of BMSCs and 1.6-fold increase in the cell viability over 7-day cultivation. BMSCs without guidance in the PLGA/chitosan scaffolds were prone to differentiate toward osteoblasts with apparent deposition of calcium. When NGF was introduced, an increased weight percentage of PLGA yielded more identified neurons. In addition, mature neurons emerged from the PLGA-rich biomaterials after induction with NGF over 2 days. A proper control over the physical and biomedical property of the scaffolds and the NGF-guided differentiation of BMSCs can be promising for nerve regeneration.

Characterization and electrochemical application of carbon materials based on poly(phenylene oxide)

NASA Astrophysics Data System (ADS)

Gray, Hunter

Carbon materials possess excellent electrical and surface properties for the next generation of energy storage devices. Polymers provide a carbon rich and tailorable precursor for the production of carbon materials. Therefore, activated carbons were prepared from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) via a three step process: thermal oxidation, carbonization, and activation with KOH. The activated carbons are predominately microporous with BET specific surface areas up to 2638 m2/g. Impedance spectroscopy revealed these carbons possess electrical conductivities comparable to commercial carbon blacks and consequently were employed in thin-film composite electrodes in electrochemical double-layer capacitors. Cyclic voltammetry confirmed maximum specific capacitances of 13.23 F/g and 2.848 F/g for aqueous and organic electrolyte systems, respectively. Additionally, carbon nanotubes were synthesized from PPO and other polymers with a nickel catalyst via chemical vapor deposition as revealed by transmission electron microscopy. This is the first report of carbon nanotubes produced from PPO.

A novel flexible room temperature ethanol gas sensor based on SnO2 doped poly-diallyldimethylammonium chloride.

PubMed

Zhan, Shuang; Li, Dongmei; Liang, Shengfa; Chen, Xin; Li, Xia

2013-04-02

A novel flexible room temperature ethanol gas sensor was fabricated and demonstrated in this paper. The polyimide (PI) substrate-based sensor was formed by depositing a mixture of SnO2 nanopowder and poly-diallyldimethylammonium chloride (PDDAC) on as-patterned interdigitated electrodes. PDDAC acted both as the binder, promoting the adhesion between SnO2 and the flexible PI substrate, and the dopant. We found that the response of SnO2-PDDAC sensor is significantly higher than that of SnO2 alone, indicating that the doping with PDDAC effectively improved the sensor performance. The SnO2-PDDAC sensor has a detection limit of 10 ppm at room temperature and shows good selectivity to ethanol, making it very suitable for monitoring drunken driving. The microstructures of the samples were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM) and Fourier transform infrared spectra (FT-IR), and the sensing mechanism is also discussed in detail.

Label-free potentiometric biosensor based on solid-contact for determination of total phenols in honey and propolis.

PubMed

Draghi, Patrícia Ferrante; Fernandes, Julio Cesar Bastos

2017-03-01

We developed a label-free potentiometric biosensor using tyrosinase extracted from Musa acuminata and immobilized by covalent bond on a surface of a solid-contact transducer. The transducer was manufactured containing two layers. The first layer contained a blend of poly(vinyl) chloride carboxylated (PVC-COOH), graphite and potassium permanganate. On this layer, we deposited a second layer containing just a mixture of poly(vinyl chloride) carboxylated and graphite. On the last layer of the transducer, we immobilized the tyrosinase enzyme by reaction with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride. The solid-contact potentiometric biosensor presented at low detection limit of 7.3×10 -7 M and a linear range to catechol concentration between 9.3×10 -7 M and 8.3×10 -2 M. This biosensor was applied to determine the amount of total phenols in different samples of honey and propolis. The results agreed with the Folin-Ciocalteu method. Copyright © 2016 Elsevier B.V. All rights reserved.

Acoustic Behavior of Subfloor Lightweight Mortars Containing Micronized Poly (Ethylene Vinyl Acetate) (EVA).

PubMed

Brancher, Luiza R; Nunes, Maria Fernanda de O; Grisa, Ana Maria C; Pagnussat, Daniel T; Zeni, Mára

2016-01-15

This paper aims to contribute to acoustical comfort in buildings by presenting a study about the polymer waste micronized poly (ethylene vinyl acetate) (EVA) to be used in mortars for impact sound insulation in subfloor systems. The evaluation method included physical, mechanical and morphological properties of the mortar developed with three distinct thicknesses designs (3, 5, and 7 cm) with replacement percentage of the natural aggregate by 10%, 25%, and 50% EVA. Microscopy analysis showed the surface deposition of cement on EVA, with preservation of polymer porosity. The compressive creep test estimated long-term deformation, where the 10% EVA sample with a 7 cm thick mortar showed the lowest percentage deformation of its height. The impact noise test was performed with 50% EVA samples, reaching an impact sound insulation of 23 dB when the uncovered slab was compared with the 7 cm thick subfloor mortar. Polymer waste addition decreased the mortar compressive strength, and EVA displayed characteristics of an influential material to intensify other features of the composite.

Covalent attachment of a bioactive hyperbranched polymeric layer to titanium surface for the biomimetic growth of calcium phosphates

PubMed Central

Tsiourvas, D.; Arkas, M.; Diplas, S.; Mastrogianni, E.

2010-01-01

This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid. PMID:21069559

Target binding influences permeability in aptamer-polyelectrolyte microcapsules.

PubMed

Sultan, Yasir; DeRosa, Maria C

2011-05-09

Aptamer-polyelectrolyte microcapsules are prepared for potential use as triggered delivery vehicles and microreactors. The hollow microcapsules are prepared from the sulforhodamine B aptamer and the polyelectrolytes poly(allylamine hydrochloride) and poly(sodium 4-styrene-sulfonate), using layer-by-layer (LbL) film deposition templated on a sacrificial CaCO(3) spherical core. Scanning electron microscopy and confocal microscopy confirm the formation of spherical CaCO(3) cores and LbL-aptamer microcapsules. Colocalization studies with fluorescently-tagged aptamer and sulforhodamine B verify the ability of the aptamer to recognize its cognate target in the presence of the K(+) ions that are required for its characteristic G-quadruplex formation. Fluorescence recovery after photobleaching studies confirms a significant difference in the permeability of the aptamer-polyelectrolyte microcapsules for the sulforhodamine B dye target compared to control microcapsules prepared with a random oligonucleotide. These results suggest that aptamer-based 'smart' responsive films and microcapsules could be applied to problems of catalysis and controlled release. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Covalent attachment of a bioactive hyperbranched polymeric layer to titanium surface for the biomimetic growth of calcium phosphates.

PubMed

Tsiourvas, D; Tsetsekou, A; Arkas, M; Diplas, S; Mastrogianni, E

2011-01-01

This work is investigating the chemical grafting on Ti surface of a polymer/calcium phosphate coating of improved adhesion for enhanced bioactivity. For this purpose, a whole new methodology was developed based on covalently attaching a hyperbranched poly(ethylene imine) layer on Ti surface able to promote calcium phosphate formation in a next deposition stage. This was achieved through an intermediate surface silanization step. The research included optimization both of the reaction conditions for covalently grafting the intermediate organosilicon and the subsequent hyperbranched poly(ethylene imine) layers, as well as of the conditions for the mechanical and chemical pretreatment of Ti surface before coating. The reaction steps were monitored employing FTIR and XPS analyses, whereas the surface morphology and structure of the successive coating layers were studied by SEM combined with EDS. The analysis confirmed the successful grafting of the hybrid layer which demonstrated very good ability for hydroxyapatite growth in simulated body fluid.

Lab-on-a-chip with beta-poly(vinylidene fluoride) based acoustic microagitation.

PubMed

Cardoso, V F; Catarino, S O; Serrado Nunes, J; Rebouta, L; Rocha, J G; Lanceros-Méndez, S; Minas, G

2010-05-01

This paper reports a fully integrated disposable lab-on-a-chip with acoustic microagitation based on a piezoelectric ss-poly(vinylidene fluoride) (ss-PVDF) polymer. The device can be used for the measurement, by optical absorption spectroscopy, of biochemical parameters in physiological fluids. It comprises two dies: the fluidic die that contains the reaction chambers fabricated in SU-8 and the ss-PVDF polymer deposited underneath them; and the detection die that contains the photodetectors, its readout electronics, and the piezoelectric actuation electronics, all fabricated in a CMOS microelectronic process. The microagitation technique improves mixing and shortens reaction time. Further, it generates heating, which also improves the reaction time of the fluids. In this paper, the efficiency of the microagitation system is evaluated as a function of the amplitude and the frequency of the signal actuation. The relative contribution of the generated heating is also discussed. The system is tested for the measurement of the uric acid concentration in urine.

Enhanced photoelectrochemical performance of inorganic-organic hybrid consisting of BiVO4 and PEDOT:PSS

NASA Astrophysics Data System (ADS)

Trzciński, K.; Szkoda, M.; Siuzdak, K.; Sawczak, M.; Lisowska-Oleksiak, A.

2016-12-01

The PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) was electrodeposited on a thin layer of bismuth vanadate (BiVO4) prepared using the pulsed laser deposition technique onto FTO. The inorganic-organic junction was characterized by Raman spectroscopy, UV-vis spectroscopy and scanning electron microscopy. Chronoamperometry curves, recorded under simulated solar light illumination, were performed to determine generated photocurrent during water and hydroquinone oxidation at the electrode surface. Experiments were performed for three types of electrode materials: (i) FTO/BiVO4, (ii) FTO/PEDOT:PSS and (iii) FTO/BiVO4/PEDOT:PSS in aqueous electrolyte. Almost 5 times higher photocurrent in electrolyte containing hole scavenger was generated after modification of BiVO4 photoanode with electrodeposited polymer. It is noteworthy that anodic photocurrent was stable even after 4 h of illumination. Cyclic voltammetry curves of FTO/BiVO4/PEDOT:PSS recorded before and after experiments performed under electrode illumination indicated that the organic part in tested junction is photo-corrosion resistant.

3D printed alendronate-releasing poly(caprolactone) porous scaffolds enhance osteogenic differentiation and bone formation in rat tibial defects.

PubMed

Kim, Sung Eun; Yun, Young-Pil; Shim, Kyu-Sik; Kim, Hak-Jun; Park, Kyeongsoon; Song, Hae-Ryong

2016-09-29

The aim of this study was to evaluate the in vitro osteogenic effects and in vivo new bone formation of three-dimensional (3D) printed alendronate (Aln)-releasing poly(caprolactone) (PCL) (Aln/PCL) scaffolds in rat tibial defect models. 3D printed Aln/PCL scaffolds were fabricated via layer-by-layer deposition. The fabricated Aln/PCL scaffolds had high porosity and an interconnected pore structure and showed sustained Aln release. In vitro studies showed that MG-63 cells seeded on the Aln/PCL scaffolds displayed increased alkaline phosphatase (ALP) activity and calcium content in a dose-dependent manner when compared with cell cultures in PCL scaffolds. In addition, in vivo animal studies and histologic evaluation showed that Aln/PCL scaffolds implanted in a rat tibial defect model markedly increased new bone formation and mineralized bone tissues in a dose-dependent manner compared to PCL-only scaffolds. Our results show that 3D printed Aln/PCL scaffolds are promising templates for bone tissue engineering applications.