Sample records for polyvinyl siloxane impression

  1. Accuracy of three polyvinyl siloxane putty-wash impression techniques

    Microsoft Academic Search

    Joseph Nissan; Ben-Zion Laufer; Tamar Brosh; David Assif

    2000-01-01

    Statement of problem. There is much discussion in the dental literature concerning the effect of the impression technique on the accuracy of cast restorations.Purpose. This study assessed the accuracy of 3 putty-wash impression techniques using the same impression material (polyvinyl siloxane) in a laboratory model.Material and methods. The 3 putty-wash impression techniques used were (1) 1-step (putty and wash impression

  2. “Evaluation of the Effect of Ultraviolet Disinfection on Dimensional Stability of the Polyvinyl Silioxane Impressions.” an in-Vitro Study

    PubMed Central

    Godbole, Surekha R; Dahane, Trupti M; Nimonkar, Sharayu V

    2014-01-01

    Introduction: Infection control is an important concept in the present day practice of dentistry. The prosthodontists are at an added risk of transmission because of the infection spreading through the contaminated lab equipments while working in the lab. The purpose of this study is to evaluate the effect of UV light disinfection on dimensional stability of polyvinyl siloxane impressions. Materials and Methods : Impressions were made in perforated custom tray. After polymerization of impression, half the samples were disinfected in UV light and remaining samples were not subjected to disinfection and poured in die stone which served as control group. Linear dimensions were measured on the cast with travelling microscope of 0.001accuracy. Result : The result showed that UV light disinfectant showed no significant dimensional changes on impressions. Conclusion: Hence, it can be safely used to disinfect impressions in clinical prosthodontic procedures. PMID:25386528

  3. Thiol-Ene functionalized siloxanes for use as elastomeric dental impression materials

    PubMed Central

    Cole, Megan A.; Jankousky, Katherine C.; Bowman, Christopher N.

    2014-01-01

    Objectives Thiol- and allyl-functionalized siloxane oligomers are synthesized and evaluated for use as a radical-mediated, rapid set elastomeric dental impression material. Thiol-ene siloxane formulations are crosslinked using a redox-initiated polymerization scheme, and the mechanical properties of the thiol-ene network are manipulated through the incorporation of varying degrees of plasticizer and kaolin filler. Formulations with medium and light body consistencies are further evaluated for their ability to accurately replicate features on both the gross and microscopic levels. We hypothesize that thiol-ene functionalized siloxane systems will exhibit faster setting times and greater detail reproduction than commercially available polyvinylsiloxane (PVS) materials of comparable consistencies. Methods Thiol-ene functionalized siloxane mixtures formulated with varying levels of redox initiators, plasticizer, and kaolin filler are made and evaluated for their polymerization speed (FTIR), consistency (ISO4823.9.2), and surface energy (goniometer). Feature replication is evaluated quantitatively by SEM. The Tg, storage modulus, and creep behavior are determined by DMA. Results Increasing redox initiation rate increases the polymerization rate but at high levels also limits working time. Combining 0.86 wt% oxidizing agent with up to 5 wt% plasticizer gave a working time of 3 min and a setting time of 2 min. The selected medium and light body thiol-ene formulations also achieved greater qualitative detail reproduction than the commercial material and reproduced micrometer patterns with 98% accuracy. Significance Improving detail reproduction and setting speed is a primary focus of dental impression material design and synthesis. Radical-mediated polymerizations, particularly thiol-ene reactions, are recognized for their speed, reduced shrinkage, and ‘click’ nature. PMID:24553250

  4. The effect of custom tray material type and fabrication technique on tensile bond strength of impression material adhesive systems.

    PubMed

    Abdullah, M A; Talic, Y F

    2003-03-01

    The purpose of this investigation was to evaluate the tensile bond strengths of two impression material systems (polysulphide and polyvinyl siloxane) to two custom tray materials [autopolymerizing and visible light-cured (VLC) acrylic resin]. The effect of polymerizing the tray materials directly against wax spacer and tin foil was evaluated for each material. Polymerizing tray materials against tin foil significantly increased the bond strengths of polysulphide and polyvinyl siloxane impression materials to VLC and autopolymerizing acrylic resin tray materials. Polyvinyl siloxane VLC cured against tin foil combination produced the strongest bond. The VLC resin tray material generated greater bond strength than autopolymerizing acrylic resin when polymerized against tin foil. PMID:12588506

  5. Two-piece impression procedure for implant-retained orbital prostheses.

    PubMed

    Ozcelik, Tuncer Burak; Yilmaz, Burak

    2012-01-01

    Obtaining an accurate impression of facial tissues with undercuts and extraoral implants has always been a challenge for both clinicians and patients. This report describes a three-step, two-piece technique that enables an accurate and comfortable impression of undercut tissues and extraoral implants in an orbital defect. An impression of the basal tissue surface of the defect area was made using a medium-body polyether impression material followed by an impression of the entire face of the patient made with a polyvinyl siloxane (PVS) impression material. First, the PVS impression material was removed; second, the impression posts were removed from the magnets; and third, the polyether impression was removed from the defect. The impression posts were attached to the implant analogs and placed in the negative spaces in the polyether impression. The polyether impression, which carries the implant analogs and impression posts, was placed in the PVS impression through the negative spaces. This technique minimizes trauma to the soft tissues and implants during impression making and also does not require additional materials. PMID:23057049

  6. Effect of splinting in accuracy of two implant impression techniques.

    PubMed

    de Avila, Erica Dorigatti; de Matos Moraes, Fernanda; Castanharo, Sabrina Maria; Del'Acqua, Marcelo Antonialli; de Assis Mollo, Francisco

    2014-12-01

    Because there is no consensus in the literature about the need for a splint between copings, the aim of this study was to evaluate, in vitro, the accuracy of 2 impression techniques for implant-supported prostheses. A master cast was fabricated with four parallel implant abutment analogs and a passive framework. Two groups with 5 casts each were formed: Group 1 (squared impression copings with no splint: S) and Group 2 (splinted squared impression copings, using metal drill burs and Pattern resin: SS). The impression material used was polyvinyl siloxane with open trays for standard preparation of the casts. For each cast, the framework was positioned, and a titanium screw was tightened with 10 N·cm torque in analog A, after which measurements of the abutment-framework interface gaps were performed at analogs C and D. This process was repeated for analog D. These measurements were analyzed using software. A one-way analysis of variance (ANOVA) with a confidence interval of 95% was used to analyze the data. Significant differences were detected between S and SS in relation to the master cast (P ? 0.05). The median values of the abutment-framework interface gaps were as follows: master cast: 39.64 ?m; squared impression copings with no splint: 205.86 ?m; splinted squared impression copings: 99.19 ?m. Under the limitations of this study, the technique presented for Group 2 produces better results compared with the technique used for Group 1. PMID:25506658

  7. Siloxane-modified epoxy resins

    Microsoft Academic Search

    E. M. Yorkgitis; N. S. Eiss; C. Tran; G. L. Wilkes; J. E. McGrath

    Epoxy resins chemically modified with functionally terminated poly (dimethyl siloxane), poly(dimethyl-co-methyltrifluoropropyl\\u000a siloxane), and poly(dimethyl-co-diphenyl siloxane) oligomers are described in terms of their synthesis, morphology, solid-state\\u000a properties, and friction and wear properties. The compatibility between the epoxy resin and the siloxane modifiers can be\\u000a enhanced by increasing the percentage of methyltrifluoropropyl (TFP) siloxane or diphenyl (DP) siloxane relative to dimethyl\\u000a siloxane.

  8. Polyimides containing pendent siloxane groups

    NASA Technical Reports Server (NTRS)

    Connell, John W. (inventor); St.clair, Terry L. (inventor); Hergenrother, Paul M. (inventor)

    1994-01-01

    Novel polyimides containing pendent siloxane groups (PISOX) were prepared by the reaction of functionalized siloxane compounds with hydroxy containing polyimides (PIOH). The pendent siloxane groups on the polyimide backbone offer distinct advantages such as lowering the dielectric constant and moisture resistance and enhanced atomic oxygen resistance. The siloxane containing polyimides are potentially useful as protective silicon oxide coatings and are useful for a variety of applications where atomic oxygen resistance is needed.

  9. Acetylene-Terminated Polyimide Siloxanes

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Maudgal, Shubba

    1987-01-01

    Siloxane-containing addition polyimides yield toughened high-temperature adhesives and matrix resins. Addition polyimide made by reaction of aromatic tetracarboxylic acid dianhydride with aromatic diamine in presence of ethynyl-substituted aromatic monoamine. Acetylene-terminated siloxane imide cured by heating to yield acetylene-terminated polyimide siloxane.

  10. Oligosilane-siloxane nanocomposites

    SciTech Connect

    Loy, D.A.; Jamison, G.M.; Waymouth, R.M. [Stanford Univ., CA (United States); Opperman, K.A.; Beach, J.V. [Sandia National Laboratories, Albuquerque, NM (United States)

    1996-10-01

    Zirconocene-catalyzed a-bond metathesis of phenylsilane is a mild and convenient way to generate synthetically versatile oligophenylsilane [Si(H)(Ph)]{sub n} (n {approx} 33). Free radical-initiated hydrosilation of alkoxysilanes RSiMe{sub x}(OEt){sub y} (R = allyl; x = 0, y = 3; x = 1, y = 2; x = 2, y = 1) at the oligophenylsilane Si-H bonds, followed by sol-gel hydrolysis-polycondensation, yields novel siloxanes containing the intact oligosilane chromophore. The sol-gel precursors and resulting siloxane materials have been characterized by solution and solid state multinuclear NMR, UV-VIS and IR spectroscopies and elemental analysis, and their bulk properties assessed by scanning electron microscopy, thermal and nitrogen sorption surface area analyses. The new materials` molecular and bulk properties, and the significance of processing and siloxane content on these properties, will be discussed.

  11. Siloxane-grafted membranes

    DOEpatents

    Friesen, D.T.; Obligin, A.S.

    1989-10-31

    Composite cellulosic semipermeable membranes are disclosed which are the covalently bonded reaction product of an asymmetric cellulosic semipermeable membrane and a polysiloxane containing reactive functional group. The two reactants chemically bond by ether, ester, amide or acrylate linkages to form a siloxane-grafted cellulosic membrane having superior selectivity and flux stability. Selectivity may be enhanced by wetting the surface with a swelling agent such as water.

  12. Siloxane-grafted membranes

    DOEpatents

    Friesen, Dwayne T. (Bend, OR); Obligin, Alan S. (Catonville, MD)

    1989-01-01

    Composite cellulosic semipermeable membranes are disclosed which are the covalently bonded reaction product of an asymmetric cellulosic semipermeable membrane and a polysiloxane containing reactive functional groups. The two reactants chemically bond by ether, ester, amide or acrylate linkages to form a siloxane-grafted cellulosic membrane having superior selectivity and flux stability. Selectivity may be enhanced by wetting the surface with a swelling agent such as water.

  13. Conference Impression

    E-print Network

    Hugo E. Schwarz

    1999-12-22

    This paper gives a personal impression of the conference ``Asymmetrical PNe II: From Origins to Microstructures'', flags some of the highlights, gathers together some facts and terminology, and indicates some promising future lines of work in this field.

  14. Removal of siloxanes in biogases

    Microsoft Academic Search

    Martin Schweigkofler; Reinhard Niessner

    2001-01-01

    Methods for the removal of gaseous silicon compounds in biogases are presented. In laboratory studies, various solid adsorption materials and liquid absorption solutions were evaluated for their siloxane elimination efficiencies. Among the liquid sorbents studied, concentrated nitric acid and sulfuric acid were found to be especially potent siloxane removing agents at elevated temperature. Solid adsorbents tested include activated charcoal, carbopack

  15. Comparison of dimensional accuracy of digital dental models produced from scanned impressions and scanned stone casts

    NASA Astrophysics Data System (ADS)

    Subeihi, Haitham

    Introduction: Digital models of dental arches play a more and more important role in dentistry. A digital dental model can be generated by directly scanning intraoral structures, by scanning a conventional impression of oral structures or by scanning a stone cast poured from the conventional impression. An accurate digital scan model is a fundamental part for the fabrication of dental restorations. Aims: 1. To compare the dimensional accuracy of digital dental models produced by scanning of impressions versus scanning of stone casts. 2. To compare the dimensional accuracy of digital dental models produced by scanning of impressions made of three different materials (polyvinyl siloxane, polyether or vinyl polyether silicone). Methods and Materials: This laboratory study included taking addition silicone, polyether and vinyl polyether silicone impressions from an epoxy reference model that was created from an original typodont. Teeth number 28 and 30 on the typodont with a missing tooth number 29 were prepared for a metal-ceramic three-unit fixed dental prosthesis with tooth #29 being a pontic. After tooth preparation, an epoxy resin reference model was fabricated by duplicating the typodont quadrant that included the tooth preparations. From this reference model 12 polyvinyl siloxane impressions, 12 polyether impressions and 12 vinyl polyether silicone impressions were made. All 36 impressions were scanned before pouring them with dental stone. The 36 dental stone casts were, in turn, scanned to produce digital models. A reference digital model was made by scanning the reference model. Six groups of digital models were produced. Three groups were made by scanning of the impressions obtained with the three different materials, the other three groups involved the scanning of the dental casts that resulted from pouring the impressions made with the three different materials. Groups of digital models were compared using Root Mean Squares (RMS) in terms of their dimensional accuracy, which is defined as the absolute value of deviation in micrometers from the reference model. A two-way analysis of analysis of variance (ANOVA) was applied to calculate if the measurements for the six test groups were statistically significantly different from the original reference model as well as between test groups (p <.05). Tukey's HSD was also applied to characterize the differences. Results: The mean (± SD) RMS was 29.42 ± 5.80 microns for digital models produced from polyether impression scans, 27.58 ± 5.85 microns for digital models from PVS impressions scans, and 24.08 ± 4.89 microns for digital models produced from VPES impressions scans. 26.08 ± 6.58 microns for digital models produced by scanning stone casts poured from PE, 31.67 ± 9.95 microns for digital models produced by scanning stone casts poured from PVS and 22.58 ± 2.84 microns for digital models produced by scanning stone casts poured from VPES. In the Two-Way ANOVA, the p-value for the material factor was 0.004, reflecting a statistically significant difference between the accuracy of the three impression materials, with VPES showing the highest accuracy (mean RMS = 23.33 ± 3.99 microns) followed by PE (mean RMS = 27.75 ± 6.3 microns) and PVS (mean RMS = 29.63 ± 8.25 microns). For the technique factor, the p-value was 0.870 reflecting no statistically significant difference between the accuracy of the two techniques (impression scan and stone cast scan). The mean RMS values were 27.03 ± 5.82 microns and 26.78 ± 7.85 microns, respectively. In the post-hoc tests for the material factor, a significant difference was found between the accuracy of VPES and PVS (p-value = 0.004) with VPES having the higher accuracy (lower mean RMS). No significant difference was found between the accuracies of PE and PVS (p-value = 0.576), and between the accuracies of PE and VPES (p-value = 0.054). Conclusions: Within the limitations of t

  16. Dinosaur Impressions

    NASA Astrophysics Data System (ADS)

    Taquet, Philippe

    1998-09-01

    Perhaps you are a paleontologist or have always wondered what it is like to be one. Or you are fascinated by fossils and like to read about the origins and natural history of dinosaurs. Or maybe you are an avid traveler and reader of travelogues. If you are any of these things, then this book is for you. Originally published in 1994 in French, Dinosaur Impressions is the engaging account of thirty years of travel and paleontological exploration by Philippe Taquet, one of the world's most noted paleontologists. Dr. Taquet takes the reader on a surprisingly far-flung tour ranging from the Provence countryside to the Niger desert, from the Brazilian bush to the Mongolian Steppes, and from the Laos jungle to the Moroccan mountains in search of dinosaur bones and what they have to tell us about a vanished world. With wry humor and lively anecdotes, Dr. Taquet retraces the history of paleontological research, along the way discussing the latest theories of dinosaur existence and extinction. Elegantly translated by Kevin Padian, Dinosaur Impressions provides a unique, thoughtful perspective not often encountered in American- and English-language works. This insightful, first-hand account of an exceptional career is also a travelogue par excellence that will enthrall enthusiasts and general readers alike. Philippe Taquet is the Director of the National Museum of Natural History in Paris and is a member of the French Academy of Sciences. Kevin Padian is a professor in the Department of Integrative Biology and Curator of the Museum of Paleontology at the University of California, Berkeley. He is also the editor of The Beginning of the Age of Dinosaurs (Cambridge, 1986) and The Encyclopedia of Dinosaurs (1997).

  17. Impressive Impact

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for Impressive Impact (QTVR)

    This stunning image features the heat shield impact site of NASA's Mars Exploration Rover Opportunity. This is an approximately true-color mosaic of panoramic camera images taken through the camera's 750-, 530-, and 430-nanometer filters.

    The mosaic was acquired on Opportunity's sol 330 (Dec. 28, 2004), shortly after Opportunity arrived to investigate the site where its heat shield hit the ground south of 'Endurance Crater' on Jan. 24, 2004. On the left, the main heat shield piece is inverted and reveals its metallic insulation layer, glinting in the sunlight. The main piece stands about 1 meter tall (about 3.3 feet) and about 13 meters (about 43 feet) from the rover.

    The other large, flat piece of debris near the center of the image is about 14 meters (about 46 feet) away. The circular feature on the right side of the image is the crater made by the heat shield's impact. It is about 2.8 meters (9.2 feet) in diameter but only about 5 to 10 centimeters (about 2 to 4 inches) deep. The crater is about 6 meters (about 20 feet) from Opportunity in this view. Smaller fragments and debris can be seen all around the impact site.

    The impact excavated a large amount of reddish subsurface material. Darker materials cover part of the crater's flat floor and have formed a streak or jet of material pointing toward the two largest heat shield fragments.

  18. Polyimides containing pendent siloxane groups

    NASA Technical Reports Server (NTRS)

    Connell, John W.

    1991-01-01

    The incorporation of siloxane units into the backbone of aromatic polyimides has been shown to impart certain advantages over the unmodified polyimides. These include enhanced solubility, lower moisture adsorption, lower dielectric constant, improved toughness and surface modification. Also, when exposed to an atomic oxygen environment these materials form an in-situ silicate (SiO2) surface coating which protects the underlying material from further erosion. These unique advantages make polyimide-siloxanes useful in a variety of electronic and aerospace applications. As part of an effort on high performance polymeric materials for potential aerospace applications, polyimides containing pendent siloxane groups are under study. These materials were prepared by reacting a functionalized siloxane compound with polyimides containing benzhydrol groups. Thin films of the polymers exhibited glass transition temperatures ranging from 167 to 235 C. Tensile strengths and moduli measured at 23 C ranged from 11 to 14 ksi and 250 to 450 ksi, respectively. The dielectric constant was lowered substantially from that of the unmodified polyimide.

  19. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... false Aminofunctional alkoxy alkyl siloxane. 721.9515 Section 721.9515...9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant...generically as an aminofunctional alkoxy alkyl siloxane (PMN P-96-346) is subject...

  20. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... false Aminofunctional alkoxy alkyl siloxane. 721.9515 Section 721.9515...9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant...generically as an aminofunctional alkoxy alkyl siloxane (PMN P-96-346) is subject...

  1. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Aminofunctional alkoxy alkyl siloxane. 721.9515 Section 721.9515...9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant...generically as an aminofunctional alkoxy alkyl siloxane (PMN P-96-346) is subject...

  2. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... false Aminofunctional alkoxy alkyl siloxane. 721.9515 Section 721.9515...9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant...generically as an aminofunctional alkoxy alkyl siloxane (PMN P-96-346) is subject...

  3. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Aminofunctional alkoxy alkyl siloxane. 721.9515 Section 721.9515...9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant...generically as an aminofunctional alkoxy alkyl siloxane (PMN P-96-346) is subject...

  4. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Siloxane modified silica nanoparticles (generic). 721.10119 Section...10119 Siloxane modified silica nanoparticles (generic). (a) Chemical substance...generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject...

  5. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... false Siloxane modified silica nanoparticles (generic). 721.10119 Section...10119 Siloxane modified silica nanoparticles (generic). (a) Chemical substance...generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject...

  6. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Siloxane modified silica nanoparticles (generic). 721.10119 Section...10119 Siloxane modified silica nanoparticles (generic). (a) Chemical substance...generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject...

  7. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... false Siloxane modified alumina nanoparticles (generic). 721.10120 Section...10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical substance...generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject...

  8. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... false Siloxane modified alumina nanoparticles (generic). 721.10120 Section...10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical substance...generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject...

  9. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Siloxane modified alumina nanoparticles (generic). 721.10120 Section...10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical substance...generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject...

  10. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... false Siloxane modified silica nanoparticles (generic). 721.10119 Section...10119 Siloxane modified silica nanoparticles (generic). (a) Chemical substance...generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject...

  11. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... false Siloxane modified alumina nanoparticles (generic). 721.10120 Section...10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical substance...generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject...

  12. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... false Siloxane modified alumina nanoparticles (generic). 721.10120 Section...10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical substance...generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject...

  13. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... false Siloxane modified silica nanoparticles (generic). 721.10119 Section...10119 Siloxane modified silica nanoparticles (generic). (a) Chemical substance...generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject...

  14. THERMAL DEGRADATION STUDY OF SILOXANE-DGEBA EPOXY COPOLYMERS

    Microsoft Academic Search

    SHYUE-TZOO LIN; STEVE K. HUANG

    1997-01-01

    Siloxane-modified DGEBA epoxy (ESDG) copolymers were prepared from Epikote 1001 and siloxane oligomers. Thermal stability studied by TGA of these ESDG copolymers indicates that thermal degradation is being effected by either structure or content of the siloxane moiety in the copolymers. The study reveals that siloxane-modified epoxy copolymer with phenyl-enriched siloxane oligomer (ESDG-7430) provides higher thermal stability than dimethyl siloxane

  15. Suitability of Tedlar gas sampling bags for siloxane quantification in landfill gas.

    PubMed

    Ajhar, M; Wens, B; Stollenwerk, K H; Spalding, G; Yüce, S; Melin, T

    2010-06-30

    Landfill or digester gas can contain man-made volatile methylsiloxanes (VMS), usually in the range of a few milligrams per normal cubic metre (Nm(3)). Until now, no standard method for siloxane quantification exists and there is controversy with respect to which sampling procedure is most suitable. This paper presents an analytical and a sampling procedure for the quantification of common VMS in biogas via GC-MS and polyvinyl fluoride (Tedlar) bags. Two commercially available Tedlar bag models are studied. One is equipped with a polypropylene valve with integrated septum, the other with a dual port fitting made from stainless steel. Siloxane recovery in landfill gas samples is investigated as a function of storage time, temperature, surface-to-volume ratio and background gas. Recovery was found to depend on the type of fitting employed. The siloxanes sampled in the bag with the polypropylene valve show high and stable recovery, even after more than 30 days. Sufficiently low detection limits below 10 microg Nm(-3) and good reproducibility can be achieved. The method is therefore well applicable to biogas, greatly facilitating sampling in comparison with other common techniques involving siloxane enrichment using sorption media. PMID:20685441

  16. First Impressions Experiment

    NSDL National Science Digital Library

    This is the entry page for participation in the first impressions experiment. This study allows participants to experience the formation of initial impressions and the roles minority/majority status and positive/negative attributes play in that formation process.

  17. TOWARD MINIMALLY ADHESIVE SURFACES UTILIZING SILOXANES

    EPA Science Inventory

    Three types of siloxane-based network polymers have been investigated for their surface properties towards potential applications as minimally adhesive coatings. A filled poly(dimethylsiloxane) (PDMS) elastomer, RTV it, has been studied to determine surface weldability and stabil...

  18. Polyimides That Contain Pendent Siloxane Groups

    NASA Technical Reports Server (NTRS)

    Connell, John W.; St. Clair, Terry L.; Hergenrother, Paul M.

    1996-01-01

    Polyimides containing pendent siloxane groups (PISOXs) synthesized from polyimides containing hydroxy groups (PIOHs) according to either of two alternative approaches. Addition of pendent siloxane groups to polyimide decreases dielectric constant, and decreases absorption of moisture: these changes in properties advantageous in some electronic applications. Also enhance resistance to atomic oxygen in that they undergo slight degradation to form thin protective silicon oxide coats when exposed to atomic oxygen.

  19. Evidence for a sedimentary siloxane horizon

    Microsoft Academic Search

    Robert E. Pellenbarg; David E. Tevault

    1986-01-01

    Selected samples from two Puget Sound sediment cores have been analyzed for poly(organo)siloxanes(silicones). One core was 60 years old at 30-cm depth (ages by lead-210 dating) and showed no evidence for silicones there. The second, 15 years old at depth, exhibited silicones at depth. Clearly shown is evidence for a siloxane horizon in theses two cores, with the presence of

  20. Synthesis, Characterization, Topographical Modification, and Surface Properties of Copoly(Imide Siloxane)s

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J.; Atkins, Brad M.; Belcher, Marcus A.; Connell, John W.

    2012-01-01

    Novel copoly(imide siloxane)s were synthesized from commercially available aminopropyl terminated siloxane oligomers, aromatic dianhydrides, and diamines. This synthetic approach produced copolymers with well-defined siloxane blocks linked with imide units in a random fashion. The copoly(amide acid)s were characterized by solution viscosity and subsequently used to cast thin films followed by thermal imidization in an inert atmosphere. Thin films were characterized using contact angle goniometry, attenuated total reflection Fourier transform infrared spectroscopy, confocal and optical microscopy, and tensile testing. Adhesion of micronsized particles was determined quantitatively using a sonication device. The polydimethylsiloxane (PDMS) moieties lowered the copolymer surface energy due to migration of siloxane moieties to the film s surface, resulting in a notable reduction in particle adhesion. A further reduction in particle adhesion was achieved by introducing topographical features on a scale of several to tens of microns by a laser ablation technique.

  1. Very first impressions.

    PubMed

    Bar, Moshe; Neta, Maital; Linz, Heather

    2006-05-01

    First impressions of people's personalities are often formed by using the visual appearance of their faces. Defining how quickly these impressions can be formed has critical implications for understanding social interactions and for determining the visual properties used to shape them. To study impression formation independent of emotional cues, threat judgments were made on faces with a neutral expression. Consequently, participants' judgments pertained to the personality rather than to a certain temporary emotional state (e.g., anger). The results demonstrate that consistent first impressions can be formed very quickly, based on whatever information is available within the first 39 ms. First impressions were less consistent under these conditions when the judgments were about intelligence, suggesting that survival-related traits are judged more quickly. The authors propose that low spatial frequencies mediate this swift formation of threat judgments and provide evidence that supports this hypothesis. PMID:16768559

  2. Multiparameter equations of state for selected siloxanes

    Microsoft Academic Search

    P. Colonna; N. R. Nannan; A. Guardone; E. W. Lemmon

    2006-01-01

    This article presents the development of technical equations of state for four siloxanes using the 12-parameter Span–Wagner functional form. Siloxanes are used as heat transfer fluids and working media in energy conversion applications. The investigated fluids are two linear dimethylsiloxanes, namely MM (hexamethyldisiloxane, C6H18OSi2) and MD4M (tetradecamethylhexasiloxane, C14H42O5Si6), and two cyclic dimethylsiloxanes, namely D4 (octamethylcyclotetrasiloxane, C8H24O4Si4) and D5 (decamethylcyclopentasiloxane, C10H30O5Si5).

  3. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Siloxanes and silicones, aminoalkyl, fluorooctyl...Chemical Substances § 721.9502 Siloxanes and silicones, aminoalkyl, fluorooctyl...chemical substance identified generically as siloxanes and silicones, aminoalkyl,...

  4. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Siloxanes and silicones, aminoalkyl, fluorooctyl...Chemical Substances § 721.9502 Siloxanes and silicones, aminoalkyl, fluorooctyl...chemical substance identified generically as siloxanes and silicones, aminoalkyl,...

  5. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Siloxanes and silicones, aminoalkyl, fluorooctyl...Chemical Substances § 721.9502 Siloxanes and silicones, aminoalkyl, fluorooctyl...chemical substance identified generically as siloxanes and silicones, aminoalkyl,...

  6. Siloxane treatment by adsorption into porous materials.

    PubMed

    Ricaurte Ortega, D; Subrenat, A

    2009-09-01

    Siloxanes are widely used in different applications: health care, dry cleaning, household products, paints and coatings, paper, personal care, for example. This explains their prevalence in the environment. Because of their volatile nature, most of the time they are dispersed in the atmosphere, but they can also be present in the slurry from landfills. During anaerobic digestion, when the temperature goes up to 60 degrees C, siloxanes are volatilized, forming part of the biogas. Operational problems using biogas to produce energy, heat and hydrogen have been identified. At high temperatures the siloxanes are transformed into silicate dioxide (commonly called sand transmission). These white deposits may adhere to metal or catalytic substrate surfaces, seriously reducing equipment efficiency, and this can be a reason for changing equipment warranties. Consequently, elimination of siloxanes has become very important. Unfortunately, relatively little information can be found on this subject. Nevertheless some authors have described different analytical methods for siloxane quantification, and recent studies have looked at the presence of siloxanes in landfills and the restriction on the energy recovery equipment using the biogas produced. The growing consumption of siloxanes and silicones in industrial processes consequently increase their prevalence in the environment, hampering the use of biogas as a source of 'green energy'. Therefore, the principal focus of this study is the treatment of siloxanes. Their elimination was carried out using an adsorption process with four different porous materials: activated carbon cloths (ACC), granular activated carbon (GAC), zeolite and silica gel. Two representative siloxane compounds were used in this study, hexamethyldisiloxane (L2) and octamethylcyclotetrasiloxane (D4). Adsorption kinetics and isotherms in batch reactors were performed. It was observed that the mass transfer into the porous material was more rapid for the activated carbon than for the zeolite and silica gel, congruent with the porous structure of the material. Moreover, it was found that D4 is more adsorbable than L2, due to possible interactions between the solid surface and the physical structure of the cyclic compound (D4). The influence of humidity and temperature were also studied. The increase in the temperature reduced the adsorption capacities. The influence of humidity on the adsorption was investigated under dry air and humid air at 70%. No significant difference in the adsorption capacities was found for the activated carbon and for the zeolite, but for the silica gel the mass transfer decreased considerably. For the adsorption isotherms, the maximal capacity of elimination was obtained with the activated carbon materials and was directly related to the porous structure. Thus activated carbon cloth was chosen to design the adsorption-desorption processes in a dynamic system. Thermal heating was used to achieve the regeneration process. Initial cycles have been accomplished and show the stability of the process. PMID:19886432

  7. Airbag Impressions in Soil

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken by the Mars Exploration Rover Opportunity's panoramic camera shows where the rover's airbags left impressions in the martian soil. The drag marks were made after the rover successfully landed at Meridiani Planum and its airbags were retracted. The rover can be seen in the foreground.

  8. Neurological Impress Method plus

    ERIC Educational Resources Information Center

    Flood, James; Lapp, Diane; Fisher, Douglas

    2005-01-01

    The purpose of these two studies was to redirect interest to the Neurological Impress Method, a multisensory approach to reading instruction that occurs between a teacher and a student, which has been largely forgotten in mainstream and special education circles over the past decades. In addition to its emphasis on oral reading, we included a…

  9. New interpenetrating network type siloxane polymer electrolyte.

    SciTech Connect

    Oh, B.; Hyung, Y.-E.; Vissers, D. R.; Amine, K.; Chemical Engineering

    2002-11-01

    An interpenetrating network (IPN), comb-type, siloxane-based solid polymer electrolyte solid polymer electrolyte was prepared and its electrochemical properties were evaluated. The cross-linking reaction conditions were established from accelerated rate calorimetry studies. An IPN solid ploymer electrolyte with 60 wt % of the comb-shaped siloxane showed an ionic conductivity of greater than 5x10{sup -4} S/cm at 37 C, with a wide electrochemical stability window of up to 4.5 V vs. lithium. A Li metal/solid polymer electrolyte/LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cell showed promising discharge capacities above 130 mAh/g and good cycling performance.

  10. Ultrahigh Molecular Weight Aromatic Siloxane Polymers

    NASA Technical Reports Server (NTRS)

    Ludwick, L. M.

    1983-01-01

    Silphenylene-siloxane polymers can be prepared by a condensation reaction of a diol 1,4-bis(hydroxydimethylsilyl)benzene and a silane bis(dimethylamino)dimethylsilane. Using a stepwise condensation technique, a polymer (R=CH3) with a molecular weight in excess of 1.0 x 1 million has been produced. The polymer exhibits increased thermal stability, compared to a methyl siloxane polymer without the aromatic phenyl ring in the backbone. The use of bis(dimethylamino)methylvinylsilane should allow for ready crosslinking at the vinyl sites (R=-CH=CH2) introduced into the backbone. However, under the conditions of the reaction system a high molecular weight polymer was not obtained or the polymer underwent a crosslinking process during the synthesis.

  11. Multimode siloxane polymer components for optical interconnects

    Microsoft Academic Search

    Nikolaos Bamiedakis; Joseph Beals IV; Richard V. Penty; Ian H. White; Jon V. Degroot Jr.; Terry V. Clapp; David de Shazer

    2009-01-01

    This paper presents an overview of multimode waveguides and waveguide components formed from siloxane polymer materials which are suitable for use in optical interconnection applications. The components can be cost-effectively integrated onto conventional PCBs and offer increased functionality in optical transmission. The multimode waveguides exhibit low loss (0.04 dB\\/cm at 850 nm) and low crosstalk (< -30 dB) performance, large

  12. Waxes for functional impressions.

    PubMed

    Kotsiomiti, E; McCabe, J F

    1996-02-01

    The aim of this study was to develop a wax suitable to serve as a functional impression material. Several binary mixtures of paraffin, beeswax and rosin were prepared. They were characterized by differential thermal analysis (DTA), and tested for plastic deformation, thermal expansion, detail reproduction and mechanical properties. It was found that the combinations of paraffin with rosin can function well as impression materials, as they combine a high value of plastic deformation at 37 degrees C with relatively low values at room temperature. Concentrations of rosin as small as 1% or 2% are adequate to produce this result. The flow of paraffin was significantly reduced by the addition of beeswax. A linear relationship was found between the 37 degrees C flow values of paraffin-beeswax mixtures and the proportions of the ingredients. PMID:8850062

  13. Some impressions of the department

    E-print Network

    Sorkin, Michael David

    1984-01-01

    This thesis comprises a series of impressions of the Department of Architecture, garnered after a long absence from M.I.T. These impressions are meant as an intervention in the Department's current self-analysis and debate ...

  14. Tool for Taking Clay Impressions

    NASA Technical Reports Server (NTRS)

    Duncan, R. S.

    1984-01-01

    Clay impression of small parts taken with tool consisting of hollow tube closed at one end. Slots at other end admit part short distance into tube. Impression used to make silicone rubber mold for examination.

  15. Implant overdenture impressions using a dynamic impression concept

    PubMed Central

    Lee, Byung-Kil; Park, Sang-Hun; Lee, Cheong-Hee

    2014-01-01

    A dynamic impression is a functional impression that records the functional movement of the patient's own muscle and muscle attachment. This process reduces the number of random factors. This article describes a method for making a special tray using a dynamic impression concept that was made from provisional dentures used for implant healing. The individual tray is used to make a wash-impression to record the features of the mucosa in detail. The main advantage of this technique is that it provides a functional relationship of the implant components to the supporting tissues without overextension because provisional denture had been used for 2 months and the border length of individual tray was nearly the same as that of provisional denture. The delivery of the prosthesis constructed using this impression technique is time-saving because there is no need for border molding and there are fewer post-insertion appliance adjustments. PMID:24605209

  16. Kinetic investigation of the solvation of lithium salts in siloxanes.

    SciTech Connect

    Chen, Z.; Wang, H. H.; Vissers, D. R.; Zhang, L.; West, R.; Lyons, L. J.; Amine, K.; Chemical Sciences and Engineering Division; Univ. of Wisconsin; Grinnell Coll.

    2008-02-14

    The solvation of lithium salts in siloxanes was investigated with the aim to understand the key barriers that limit the ionic conductivity of siloxane-based electrolytes. The conductivity and kinetic data were measured for electrolytes with different salts, different salt concentrations, and solvents. The results show that both the conductivity and the kinetics of ionic transportation were greatly impacted by the specific interactions between ions and the solvent molecules. The high content of ion pairs in the electrolytes can be one of the main reasons for the low ionic conductivity observed in the siloxane-based electrolytes.

  17. Making a Great First Impression

    ERIC Educational Resources Information Center

    Evenson, Renee

    2007-01-01

    Managers and business owners often base hiring decisions on first impressions. That is why it is so important to teach students to make a great first impression--before they go on that first job interview. Managers do not have unrealistic expectations, they just want to hire people who they believe can develop into valuable employees. A nice…

  18. New siloxane–ester modified polysulfones by phase transfer catalysis

    Microsoft Academic Search

    C Racle?; E Avram; M Marcu; V Cozan; M Cazacu

    2000-01-01

    Chemical modification of a chloromethylated polysulfone was performed by using siloxane-containing aliphatic carboxylic salts as modification agents and phase transfer catalysis. The obtained substitution degrees ranged between around 0.1 and 0.9, as determined by 1H NMR, IR and elemental analyses. The introduction of siloxane–aliphatic moieties induced a decrease in the glass transition temperature (Tg) values of the obtained products in

  19. Separation of aroma compounds from aqueous solutions by pervaporation using polyoctylmethyl siloxane (POMS) and polydimethyl siloxane (PDMS) membranes

    Microsoft Academic Search

    P Sampranpiboon; R Jiraratananon; D Uttapap; X Feng; R. Y. M Huang

    2000-01-01

    Pervaporation separation was used to recover aroma compounds from ethyl butanoate (ETB)–H2O, ethyl hexanoate (ETH)–H2O mixtures, and ETB–ETH–H2O mixtures using polyoctylmethyl siloxane (POMS) and polydimethyl siloxane (PDMS) membranes. The effects of operating conditions (e.g., downstream pressure, feed concentration, feed flow rate, and temperature) on the separation performance were investigated. It was shown that decreasing downstream pressure increased both permeation flux

  20. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Impression tube. 872.6570 Section 872.6570 Food and...Miscellaneous Devices § 872.6570 Impression tube. (a) Identification. An impression tube is a device consisting of a hollow...

  1. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Impression tube. 872.6570 Section 872.6570 Food and...Miscellaneous Devices § 872.6570 Impression tube. (a) Identification. An impression tube is a device consisting of a hollow...

  2. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Impression tube. 872.6570 Section 872.6570 Food and...Miscellaneous Devices § 872.6570 Impression tube. (a) Identification. An impression tube is a device consisting of a hollow...

  3. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2010-04-01 false Impression tube. 872.6570 Section 872.6570 Food and...Miscellaneous Devices § 872.6570 Impression tube. (a) Identification. An impression tube is a device consisting of a hollow...

  4. Comparative Properties of Siloxane vs Phosphonate Monolayers on A Key Titanium Alloy

    E-print Network

    Schwartz, Jeffrey

    Comparative Properties of Siloxane vs Phosphonate Monolayers on A Key Titanium Alloy Brett M a phosphonate and two siloxane monolayers formed on the native oxide surface of Ti-6Al-4V. Surface loading for the phosphonate was ca. four times greater (on a nanomole/area basis) than for the siloxanes; mechanical strengths

  5. Optimization of Poly-Di-Methyl-Siloxane (PDMS) substrates for studying cellular adhesion and motility

    E-print Network

    Paris-Sud XI, Université de

    Optimization of Poly-Di-Methyl-Siloxane (PDMS) substrates for studying cellular adhesion-Di-Methyl- Siloxane (PDMS) substrate. We show how a wide range of PDMS rigidity can be obtained and how Ar/O2-based recovery6,7 , phagocytosis7,8,9,10 , or metastases development4,11 for instance. As Poly-Di-Methyl-Siloxane

  6. Biocompatibility and Reduced Drug Absorption of Sol-Gel-Treated Poly(dimethyl siloxane) for

    E-print Network

    Quake, Stephen R.

    Biocompatibility and Reduced Drug Absorption of Sol-Gel-Treated Poly(dimethyl siloxane Francisco, California 94143, United States Poly(dimethyl siloxane) (PDMS)-based microfluidic de- vices(dimethyl siloxane) (PDMS) is a popular material for making microfluidic devices. This widespread utility stems from

  7. Hybrid scaffold bearing polymer-siloxane Schiff base linkage for bone tissue engineering.

    PubMed

    Nair, Bindu P; Gangadharan, Dhanya; Mohan, Neethu; Sumathi, Babitha; Nair, Prabha D

    2015-07-01

    Scaffolds that can provide the requisite biological cues for the fast regeneration of bone are highly relevant to the advances in tissue engineering and regenerative medicine. In the present article, we report the fabrication of a chitosan-gelatin-siloxane scaffold bearing interpolymer-siloxane Schiff base linkage, through a single-step dialdehyde cross-linking and freeze-drying method using 3-aminopropyltriethoxysilane as the siloxane precursor. Swelling of the scaffolds in phosphate buffered saline indicates enhancement with increase in siloxane concentration, whereas compressive moduli of the wet scaffolds reveal inverse dependence, owing to the presence of siloxane, rich in silanol groups. It is suggested that through the strategy of dialdehyde cross-linking, a limiting siloxane loading of 20 wt.% into a chitosan -gelatin matrix should be considered ideal for bone tissue engineering, because the scaffold made with 30 wt.% siloxane loading degrades by 48 wt.%, in 21 days. The hybrid scaffolds bearing Schiff base linkage between the polymer and siloxane, unlike the stable linkages in earlier reports, are expected to give a faster release of siloxanes and enhancement in osteogenesis. This is verified by the in vitro evaluation of the hybrid scaffolds using rabbit adipose mesenchymal stem cells, which revealed osteogenic cell-clusters on a polymer-siloxane scaffold, enhanced alkaline phosphatase activity and the expression of bone-specific genes, whereas the control scaffold without siloxane supported more of cell-proliferation than differentiation. A siloxane concentration dependent enhancement in osteogenic differentiation is also observed. PMID:25953575

  8. Statistical analysis of barefoot impressions.

    PubMed

    Kennedy, Robert B; Pressman, Irwin S; Chen, Sanping; Petersen, Peter H; Pressman, Ari E

    2003-01-01

    Comparison of the shapes of barefoot impressions from an individual with footprints or shoes linked to a crime may be useful as a means of including or excluding that individual as possibly being at the scene of a crime. The question of the distinguishability of a person's barefoot print arises frequently. This study indicates that measurements taken from the outlines of inked footprint impressions show a great degree of variability between donors and a great degree of similarity for multiple impressions taken from the same donor. The normality of the set of measurements on footprint outlines that we have selected for this study is confirmed. A statistical justification for the use of the product rule on individual statistical precisions is developed. PMID:12570199

  9. Diffusion of low molecular weight siloxane from bulk to surface

    Microsoft Academic Search

    H. Homma; T. Kuroyagi; K. Izumi; C. L. Mirley; J. Ronzello; S. A. Boggs

    1999-01-01

    Silicone-based materials for outdoor insulators have the advantage that low molecular weight (LMW) components migrate through the material and coat the surface, thereby restoring hydrophobicity over a period of hours. By measuring the IR absorption of siloxane migrating to the silicone surface through a thin carbon coating, the time constant for migration was calculated. According to the time dependence of

  10. Safe human exposure limits for airborne linear siloxanes during spaceflight

    PubMed Central

    García, Hector D.; McMullin, Tami S.; Tobin, Joseph M.; James, John T.

    2013-01-01

    Background Low molecular weight siloxanes are used in industrial processes and consumer products, and their vapors have been detected in the atmospheres of the Space Shuttle and International Space Station. Therefore, the National Aeronautics and Space Administration (NASA) developed spacecraft maximum allowable concentrations (SMACs) for siloxane vapors to protect astronaut health. Since publication of these original SMACs, new studies and new risk assessment approaches have been published that warrant re-examination of the SMACs. Objective To reevaluate SMACs published for octamethyltrisiloxane (L3) for exposures ranging from 1 hour to 180 days, to develop a 1000-day SMAC, and to expand the applicability of those values to the family of linear siloxanes. Methods A literature review was conducted to identify studies conducted since the SMACs for L3 were set in 1994. The updated data were reviewed to determine the sensitive toxicity endpoints, and current risk assessment approaches and methods for dosimetric adjustments were evaluated. Results Recent data were used to update the original 1-hour, 24-hour, 30-day, and 180-day SMACs for L3, and a 1000-day SMAC was developed to protect crewmembers during future exploration beyond Earth orbit. Group SMACs for the linear siloxane family, including hexamethyldisiloxane (L2), L3, decamethyltetrasiloxane (L4), and dodecamethylpentasiloxane (L5), were set for exposures of 1-hour to 1000 days. Conclusion New SMACs, based on acute pulmonary and neurotoxicity at high doses only achievable with L2 and potential liver effects following longer-term exposures to L2 and L3, were established to protect crewmembers from the adverse effects of exposure to linear siloxanes. PMID:24255951

  11. From hydrophobic to superhydrophobic and superhydrophilic siloxanes by thermal treatment.

    PubMed

    Karapanagiotis, Ioannis; Manoudis, Panagiotis N; Zurba, Andreea; Lampakis, Dimitrios

    2014-11-11

    The cross-influence effects of treatment temperature and time on the wettability of a siloxane elastomer is investigated in detail, through static and tilt contact angle measurements. The material is heated at 400, 500, 600, 650, 700, and 800 °C for various periods, ranging from 1 to 300 s. The siloxane surface is subjected to multiple wettability transitions with treatment time: from intrinsic hydrophobicity to superhydrophobicity (and water repellency) and then through intermediate stages (hydrophobicity and hydrophilicity) to superhydrophilicity. For the time scale used herein (1-300 s), this scenario is recorded for treatment at 650, 700, and 800 °C. For treatment at lower temperatures (400, 500, and 600 °C) only the first transition, from intrinsic hydrophobicity to superhydrophobicity, is recorded. Scanning electron microscopy, micro-Fourier transform infrared (micro-FTIR), and micro-Raman spectroscopies are employed to correlate the aforementioned wettability transitions with structural and chemical changes of the siloxane surface, developed during thermal treatment. It is shown that the first transition from intrinsic hydrophobicity to superhydrophobicity is accompanied by a severe surface-structure evolution that increases surface roughness. Once superhydrophobicity is achieved, the surface structure reaches a saturation point and it is not subjected to any other change with further thermal treatment. FTIR spectroscopy shows that the intensity of the O-H/C-H peaks increases/decreases with treatment time, and Raman measurements show that the C-Si-C vibrations gradually disappear with treatment time. The evaporation of a droplet resting on a superhydrophobic, water-repellent siloxane surface, which was produced after appropriate thermal treatment, is monitored. It is shown that droplet evaporation initially follows the constant contact area mode. At later evaporation stages, a transition to the constant contact angle mode is recorded. Finally, it is demonstrated that the superhydrophobic and water-repellent siloxane surfaces exhibit self-cleaning properties, good durability, and furthermore do not practically affect the optical transparency of glass substrates. PMID:25313653

  12. Intraoral Digital Impression Technique: A Review.

    PubMed

    Ting-Shu, Su; Jian, Sun

    2015-06-01

    With the techniques of computer-aided design and computer-aided manufacturing (CAD/CAM) being applied in the field of prosthodontics, a concept of intraoral digital impressions was put forward in the early 1980s. It has drawn comprehensive attention from dentists and has been used for dental prosthesis fabrication in a number of cases. This new digital impression technique is expected to bring about absolute digitization to the mode of prosthodontics. A few published articles have indicated that dental prostheses fabricated from intraoral digital impressions have exhibited remarkable advantages over those from conventional impressions in several respects. The present review discusses intraoral digital impression techniques in terms of the following aspects: (1) categories and principles of intraoral digital impression devices currently available; (2) operating characteristics of the devices; and (3) comparison of the manipulation, accuracy, and repeatability between intraoral digital impression and conventional impression. PMID:25220390

  13. 40 CFR 721.6170 - Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6,6-tetramethyl-4-(2-propenyloxy...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... false Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6...6170 Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6...identified as siloxanes and silicones, Me hydrogen, reaction products with...

  14. N-halamine\\/quat siloxane copolymers for use in biocidal coatings

    Microsoft Academic Search

    J. Liang; Y. Chen; K. Barnes; R. Wu; S. D. Worley; T.-S. Huang

    2006-01-01

    A series of copolymers incorporating N-halamine siloxane and quaternary ammonium salt siloxane units has been prepared. The primary function of the quat units was to render the siloxane copolymers soluble in water. The copolymers have been coated onto cotton swatches and evaluated for biocidal efficacy against Staphylococcus aureus and Escherichia coli O157:H7. It was determined that both N-halamine and quat

  15. Recyclable Polystyrene-Supported Siloxane-Transfer Agent for Palladium-Catalyzed Cross-Coupling Reactions

    PubMed Central

    2015-01-01

    The rational design, synthesis, and validation of a significantly improved insoluble polymer-supported siloxane-transfer agent has been achieved that permits efficient palladium-catalyzed cross-coupling reactions. The cross-linked polystyrene support facilitates product purification with excellent siloxane recycling. Drawbacks of a previous polymer-supported siloxane-transfer agent, relating to reaction efficiency and polymer stability after repeated cycles, have been addressed. PMID:24661113

  16. Cyclic siloxanes in the biological waste water treatment process – Determination, quantification and possibilities of elimination

    Microsoft Academic Search

    Rene Huppmann; Horst Werner Lohoff; Horst Friedrich Schröder

    1996-01-01

    .   Volatile cyclic organic siloxanes in the biogas of digested sludge can shorten the life time of gas engines producing energy\\u000a from the biogas. These siloxanes have been determined by gas chromatography on a fused-silca column using flame ionization\\u000a detection (GC\\/FID). To extract siloxanes from biogas, spiked biogas or spiked carbon dioxide XAD resins, activated carbon,\\u000a polyurethane foam and tetradecane

  17. Single-mode optical waveguide using siloxane polymer on Cu-polyimide substrate

    Microsoft Academic Search

    Shigeo TANAHASHI; K. Kaneko; M. Terasawa

    1995-01-01

    A new single mode optical waveguide has been developed to obtain optoelectronic multichip modules. It is fabricated using siloxane polymer and thin film process technology onto a copper polyimide ceramic substrate. The siloxane polymer refractive index is 1.451, very similar to that of SiO2. It is revealed that titanium doped siloxane polymer has refractive index of 1.4537 to 1.5949 (at

  18. Covalent immobilisation of protease and laccase substrates onto siloxanes

    Microsoft Academic Search

    Alexandra Rollett; Marc Schroeder; Konstantin P. Schneider; Roland Fischer; Franz Kaufmann; Rainer Schöftner; Georg M. Guebitz

    2010-01-01

    Immobilisation of enzyme substrates is a powerful tool in the detection of enzymes in the chemosphere and the environment. A siloxane based strategy for the covalent immobilisation of oxidoreductase and protease substrates was developed involving activation of silica gel and polyethylene terephthalate (PET) as model carriers with (3-aminopropyl)-triethoxysilane or (3-mercaptopropyl)-trimethoxysilane (APTS, MPTS). Ferulic acid and l-Leucine-p-nitroanilide, Gly-Phe p-nitroanilide (GPpNA) and

  19. Siloxanes removal from biogas by high surface area adsorbents.

    PubMed

    Gislon, P; Galli, S; Monteleone, G

    2013-12-01

    Biogas utilized for energy production needs to be free from organic silicon compounds, as their burning has damaging effects on turbines and engines; organic silicon compounds in the form of siloxanes can be found in biogas produced from urban wastes, due to their massive industrial use in synthetic product, such as cosmetics, detergents and paints. Siloxanes removal from biogas can be carried out by various methods (Mona, 2009; Ajhar et al., 2010 May; Schweigkofler and Niessner, 2001); aim of the present work is to find a single practical and economic way to drastically and simultaneously reduce both the hydrogen sulphide and the siloxanes concentration to less than 1 ppm. Some commercial activated carbons previously selected (Monteleone et al., 2011) as being effective in hydrogen sulfide up taking have been tested in an adsorption measurement apparatus, by flowing the most volatile siloxane (hexamethyldisiloxane or L2) in a nitrogen stream, typically 100-200 ppm L2 over N2, through an activated carbon powder bed; the adsorption process was analyzed by varying some experimental parameters (concentration, grain size, bed height). The best activated carbon shows an adsorption capacity of 0.1g L2 per gram of carbon. The next thermogravimetric analysis (TGA) confirms the capacity data obtained experimentally by the breakthrough curve tests. The capacity results depend on L2 concentration. A regenerative carbon process is then carried out by heating the carbon bed up to 200 °C and flushing out the adsorbed L2 samples in a nitrogen stream in a three step heating procedure up to 200 °C. The adsorption capacity is observed to degrade after cycling the samples through several adsorption-desorption cycles. PMID:24075968

  20. Kinetic aspects of the thermal degradation of poly(dimethyl siloxane) and poly(dimethyl diphenyl siloxane)

    Microsoft Academic Search

    Girish Deshpande; Mary E Rezac

    2002-01-01

    The kinetics of degradation of polysiloxanes with different starting chemistries is reported in this paper. The polymers used in the study were vinyl-terminated polydimethylsiloxane (PDMS) and poly(diphenyl-dimethyl)siloxane (3.5 and 25% diphenyl content, DP-3.5 and DP-25). These polymers were inert pyrolyzed under isothermal conditions at temperatures from 325 to 400 °C for 5 h. Additionally, these polymers were pyrolyzed under dynamic heating

  1. Fungal degradation of polyvinyl acetate.

    PubMed

    García Trejo, A

    1988-08-01

    Certain Aspergillus and Penicillium strains isolated from soil grow well and degrade a commercial sample of polyvinyl acetate (PVA, 4.5 g liter-1) when it is used as the only carbon source. These strains showed an increase in dry weight after 11 days of incubation, along with a depletion of carbohydrates, protein, and deoxyribonucleic acid. This was interpreted as an active turnover of the above metabolites during the degradation. This effect was greatly enhanced by equilibrating the carbon:nitrogen ratio by addition of yeast extract in the original culture. The increase in esterase activity and the loss of viscosity were also considered evidence of the fungal degradation. Isolation of the enzyme was attempted, but unsuccessful. PMID:3181066

  2. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...3660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification....

  3. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...3660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification....

  4. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...3660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification....

  5. Figure 1: Functionalization of TiO2 by anhydrous chemical vapor deposition of trifunctional siloxane adsorbates.

    E-print Network

    Figure 1: Functionalization of TiO2 by anhydrous chemical vapor deposition of trifunctional siloxane adsorbates. Characterization of Siloxane Adsorbates Covalently Attached to TiO2 Nobuhito Iguchi, Clyde Cady 208107, New Haven, Connecticut, 06520-8107, U.S.A. ABSTRACT Siloxanes with the general formula R-(CH2)n

  6. Invited Paper to appear in Current Analytical Chemistry Real-Time Monitoring of Siloxane Monolayer Film Formation on Silica Using

    E-print Network

    Dagenais, Mario

    Invited Paper to appear in Current Analytical Chemistry Real-Time Monitoring of Siloxane Monolayer (i.e. silica, mica) or to another silane molecule through formation of a siloxane bond [1 the silanization process, an adsorbed water layer is involved in the formation of the newly forming siloxane layer

  7. The Preparation and Characterization of Small Mesopores in Siloxane-Based Materials That Use Cyclodextrins as Templates

    E-print Network

    Gidley, David

    The Preparation and Characterization of Small Mesopores in Siloxane-Based Materials That Use to their many desirable properties, such as small molecular size (14 ~ 17 ), compatible with siloxane), and low cost. The purpose of our work is to make siloxane-based porous thin films with small mesopores

  8. Controlled formation of silica structures using siloxane/block copolymer complexes prepared in various solvent mixtures.

    PubMed

    Kataoka, Sho; Takeuchi, Yasutaka; Kawai, Akiko; Yamada, Mitsuhiko; Kamimura, Yoshihiro; Endo, Akira

    2013-11-01

    Block copolymers exhibit regularly patterned structures induced by microphase separation. Here we present a method for preparing various particulate silica (SiO2) nanostructures by controlling the microphase separation of block copolymers. In this method, siloxane, a SiO2 precursor, is adsorbed onto poly(4-vinylpyridine) blocks of polystyrene-block-poly(4-vinylpyridine) in solvent mixtures. After siloxane/polymer complexes are coprecipitated via further siloxane polycondensation, the resulting precipitates are heated to remove the polymer. The results of scanning electron microscopy revealed that SiO2 formed various structures including cylindrical, spherical, and lamellar. Different SiO2 nanostructures formed via the microphase separation of siloxane/polymer complexes are prepared simply by varying solvent mixtures without changing the polymer chain. The structural change is interpreted in terms of polymer-solvent interactions and volume fractions in siloxane/polymer complexes. PMID:24093890

  9. A nationwide survey and emission estimates of cyclic and linear siloxanes through sludge from wastewater treatment plants in Korea.

    PubMed

    Lee, Sunggyu; Moon, Hyo-Bang; Song, Geum-Ju; Ra, Kongtae; Lee, Won-Chan; Kannan, Kurunthachalam

    2014-11-01

    Siloxanes are widely used in various industrial applications as well as in personal care products. Despite their widespread use and potential toxic effects, few studies have reported on the occurrence of siloxanes in the environment. In this study, we determined the concentrations of 5 cyclic and 15 linear siloxanes in sludge collected from 40 representative wastewater treatment plants (WWTPs) in Korea. Total concentrations of 20 siloxanes (?siloxane) in sludge ranged from 0.05 to 142 (mean: 45.7) ?g/g dry weight, similar to the concentrations reported in European countries but higher than those reported in China. The concentrations of siloxanes in sludge from domestic WWTPs were significantly (p<0.01) higher than those from industrial WWTPs, indicating higher consumption of siloxanes in various personal care products (e.g. shampoos and conditioners). The major siloxane compounds found in sludge were decamethylcyclopentasilane (D5), docosamethyldecasiloxane (L10) and dodecamethylcyclohexasilane (D6), which collectively accounted for, on average, 62% of the ?siloxane concentrations. Non-parametric multidimensional scaling ordination of the profiles of siloxanes indicated the existence of different usage patterns of siloxanes between industrial and household activities. Multiple linear regression analysis of siloxane concentrations and WWTP characteristics suggested that D5, D6 and linear siloxane concentrations in sludge were positively correlated with population served by a WWTP. Environmental emission fluxes of cyclic and linear siloxanes through sludge disposal in Korea were 14,800 and 18,500 kg/year, respectively. This is the first report describing occurrence and environmental emission of siloxanes through sludge in Korea. PMID:25127445

  10. A Teacher's Impressions of the Soviet Union.

    ERIC Educational Resources Information Center

    Thomas, Anne

    1987-01-01

    Reports the impressions of an 11th-grade world cultures teacher who visited European Russia and Uzbekistan in August, 1985. Ten major impressions are detailed, among them are (1) the poverty, (2) the sloppiness, (3) the pervasive presence of Lenin, and (4) the cultural importance of the Babushka, the Russian word for grandmother. (JDH)

  11. The neural dynamics of updating person impressions

    PubMed Central

    Cai, Yang; Todorov, Alexander

    2013-01-01

    Person perception is a dynamic, evolving process. Because other people are an endless source of social information, people need to update their impressions of others based upon new information. We devised an fMRI study to identify brain regions involved in updating impressions. Participants saw faces paired with valenced behavioral information and were asked to form impressions of these individuals. Each face was seen five times in a row, each time with a different behavioral description. Critically, for half of the faces the behaviors were evaluatively consistent, while for the other half they were inconsistent. In line with prior work, dorsomedial prefrontal cortex (dmPFC) was associated with forming impressions of individuals based on behavioral information. More importantly, a whole-brain analysis revealed a network of other regions associated with updating impressions of individuals who exhibited evaluatively inconsistent behaviors, including rostrolateral PFC, superior temporal sulcus, right inferior parietal lobule and posterior cingulate cortex. PMID:22490923

  12. Tissue conditioning materials as functional impression materials.

    PubMed

    Chander, Satinder; Hill, Mark; Moore, Derek; Morrow, Leean

    2007-06-01

    There has been much written on the subject of tissue conditioner materials. In the context of functional impressions however there exists a lack of consensus opinion. In this article various aspects of functional impression materials have been considered. These include the effects of powder to liquid mixing ratio (P/L) on the visco elastic properties, effects on the surface hardness of dental stone when these materials are cast, undercut reproducibility, compressibility and dimensional stability. Definitive conclusions are difficult to draw however it seems the evidence supports the use of tissue conditioners as functional impression materials. PMID:17645067

  13. Adsorption characteristics of siloxanes in landfill gas by the adsorption equilibrium test

    SciTech Connect

    Nam, Sangchul; Namkoong, Wan [Department of Environmental Engineering, Konkuk University, Hwayang-Dong, Gwangjin-Gu, Seoul 143-701 (Korea, Republic of); Kang, Jeong-Hee; Park, Jin-Kyu [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of); Lee, Namhoon, E-mail: nhlee@anyang.ac.kr [Department of Environmental Engineering, Anyang University, Anyang 5-Dong, Manan-Gu, Anyang-Si, Gyeonggi-Do 430-714 (Korea, Republic of)

    2013-10-15

    Highlights: • Equilibrium test was attempted to evaluate adsorption characteristics of siloxane. • L2 had higher removal efficiency in carbon compared to noncarbon adsorbents. • Total adsorption capacity of siloxane was 300 mg/g by coal activated carbon. • Adsorption characteristics rely on size of siloxane molecule and adsorbent pore. • Conversion of siloxane was caused by adsorption of noncarbon adsorbents. - Abstract: Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane.

  14. 21 CFR 872.6880 - Preformed impression tray.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...Identification. A preformed impression tray is a metal or plastic device intended to hold impression material, such as alginate, to make an impression of a patient's teeth or alveolar process (bony tooth sockets) to reproduce the structure of a...

  15. Shark fin test and impression quality: A correlation analysis

    Microsoft Academic Search

    Markus Balkenhol; Bernd Wöstmann; Masafumi Kanehira; Werner J. Finger

    2007-01-01

    ObjectivesTo evaluate the correlation between the shark fin test and the dimensional accuracy of impressions, surface detail reproduction of impressions and rheological properties of impression materials within the manufacturer's recommended working time.

  16. First Impressions of Eastern European Education.

    ERIC Educational Resources Information Center

    Spoleti, Linda Higgins

    1995-01-01

    Describes the first impressions of a high school teacher on her first day of teaching conversational English at a secondary school in Budapest, Hungary. Notes the great variation in students' English language skills. (RS)

  17. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...6570 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6570 Impression tube. (a) Identification. An...

  18. Enhancement of footwear impressions in blood.

    PubMed

    Theeuwen, A B; van Barneveld, S; Drok, J W; Keereweer, I; Limborgh, J C; Naber, W M; Velders, T

    1998-07-20

    Methods for chemical enhancement of footwear impressions in blood were compared in order to make a separation between utilization at the scene of crime, the local (regional) police laboratory and the Dutch Forensic Science Laboratory (DFSL). PMID:9722976

  19. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material...intended to provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures....

  20. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material...intended to provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures....

  1. Going To Work: Make a Good Impression 

    E-print Network

    Hoffman, Rosemarie

    2000-01-07

    A person's goals, self-image, personality, attitude, personal hygiene and concern for family can make a major impression on an employer. This publication offers tips on presenting a good image on the job....

  2. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...2010-04-01 2009-04-01 true Polyvinyl alcohol film. 177.1670 Section 177.1670 Food and Drugs...Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of...

  3. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...2011-04-01 2011-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670 Food and Drugs...Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of...

  4. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...2013-04-01 2013-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670 Food and Drugs...Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of...

  5. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...2014-04-01 2014-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670 Food and Drugs...Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of...

  6. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...2012-04-01 2012-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670 Food and Drugs...Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of...

  7. Poly(imide-siloxane) segmented copolymer structural adhesives prepared by bulk and solution thermal imidization

    NASA Technical Reports Server (NTRS)

    Bott, R. H.; Summers, J. D.; Arnold, C. A.; Blankenship, C. P., Jr.; Taylor, L. T.

    1988-01-01

    The improved properties that have been demonstrated through thermal solution imidization in the case of polyimides and poly(imide-siloxane) segmented copolymers suggests significant potential for application of these new materials. Specifically, the enhancement in solubility, moisture reduction, and processability observed through this solution technique is quite dramatic. Previous work has shown that the presence of low amounts of siloxane does not detract significantly from the lap shear strength of these materials to titanium in the case of bulk thermal imidization synthesis. In addition, the siloxane incorporation results in the added advantage of resistance to hot, wet environments. This added durability is presumably due to the hydrophobic siloxane segments preventing the uptake of water at the critical interphase between the adhesive and the adherend. This paper discusses the extension of this work to the solution imidization synthesis technique recently developed in our laboratory. Results dealing with the absolute bond strengths as well as durability and failure surface analysis will be presented.

  8. Preparation and characterization of a siloxane containing bismaleimide

    NASA Technical Reports Server (NTRS)

    Maudgal, S.; St. Clair, T. L.

    1984-01-01

    A novel siloxane containing bismaleimide has been prepared by reacting maleic anhydride, benzophenonetetracarboxylic dianhydride and bis(gamma-aminopropyl)tetramethyldisiloxane. Characterization of this monomer was done by comparing its nuclear magnetic resonance spectrum (NMR) to those of model compounds. Solubility of the prepolymer was tested in amide, chlorinated and ether solvents. Films were cast from solution as well as by melt processing and a cure cycle was determined. Infrared spectrum (IR) of the resulting film was obtained. Thermal polymerization was investigated by differential scanning calorimetry (DSC). Thermal properties of the cured resin were followed by means of thermogravimetric analysis (TGA), torsional braid analysis (TBA) and dynamic mechanical analysis (DMA). Thermomechanical analysis (TMA) was used to study the effect of postcure on the glass transition temperature (Tg) of the resin. Adhesive strength of the resin was obtained at ambient temperature.

  9. Synthesis, characterization and development of high performance siloxane-modified epoxy paints

    Microsoft Academic Search

    Sharif Ahmad; A. P. Gupta; Eram Sharmin; Manawwer Alam; S. K. Pandey

    2005-01-01

    Diglycidyl ether of bisphenol A (DGEBA) epoxy was modified with hydroxyl-terminated poly dimethyl siloxane (HPDMS), through ring opening addition polymerization reaction. The structural elucidation of the siloxane-modified epoxy resin (ESR) was carried out by FT-IR, 1H-NMR and 13C-NMR spectroscopic techniques. The physico-chemical characterization of the synthesized resin (ESR) was done by standard methods. DGEBA and ESR, were subjected to paint

  10. Poly(imide siloxane) and carbon nanotube mixed matrix membranes for gas separation

    Microsoft Academic Search

    Sangil Kim; Todd W. Pechar; Eva Marand

    2006-01-01

    Recent theoretical work by Sholl and coworkers has predicted that carbon nanotubes, if used as membranes, have the flux\\/selectivity properties that far exceed those of any other known inorganic or organic material. To verify this prediction, we have fabricated nano-composite membranes consisting of single-walled carbon nanotubes embedded in a poly(imide siloxane) copolymer and evaluated their transport properties. While the siloxane

  11. Thermodynamic analysis of high-temperature regenerative organic Rankine cycles using siloxanes as working fluids

    Microsoft Academic Search

    F. J. Fernández; M. M. Prieto; I. Suárez

    2011-01-01

    A recent novel adjustment of the Span–Wagner equation of state for siloxanes, used as working fluids in high-temperature organic Rankine cycles, is applied in a mathematical model to solve cycles under several working conditions. The proposed scheme includes a thermo-oil intermediate heat circuit between the heat source and the organic Rankine cycle. Linear and cyclic siloxanes are assayed in saturated,

  12. Survey of Organosilicone Compounds, Including Cyclic and Linear Siloxanes, in Personal-Care and Household Products

    Microsoft Academic Search

    Yuichi Horii; Kurunthachalam Kannan

    2008-01-01

    The determination of organosiloxanes in consumer products is important for the evaluation and characterization of sources\\u000a of human and environmental exposures. In this study, we determined concentrations of cyclic siloxanes [octamethylcyclotetrasiloxane\\u000a (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6)], tetradecamethylcycloheptasiloxane (D7)] and linear siloxanes (L4 to L14) in a variety of consumer products (n = 76), including hair-care products, skin lotions, body washes, cosmetics, nursing

  13. Polyfunctional Biologically Active Polyvinyl Alcohol Film Materials

    Microsoft Academic Search

    T. N. Yudanova; I. F. Skokova; E. Yu. Aleshina; L. S. Gal'braikh

    2001-01-01

    Incorporation of sodium alginate in the spinning solution in the amount of 2% decreases the rate of inactivation of protease C immobilized in the structure of a polyvinyl alcohol film material by two times and decreases the amount of desorbed polyhexamethyleneguanidine hydrochloride by ten times, giving the film self-disinfecting properties. Addition of sodium tetraborate in the spinning solution increases the

  14. Siloxanes: A new class of candidate Bethe-Zel'dovich-Thompson fluids

    NASA Astrophysics Data System (ADS)

    Colonna, P.; Guardone, A.; Nannan, N. R.

    2007-08-01

    This paper presents a new class of Bethe-Zel'dovich-Thompson fluids, which are expected to exhibit nonclassical gasdynamic behavior in the single-phase vapor region. These are the linear and cyclic siloxanes, light silicon oils currently employed as working fluids in organic Rankine cycle turbines. State-of-the-art multiparameter equations of state are used to describe the thermodynamic properties of siloxanes and to compute the value of the fundamental derivative of gasdynamics ?, whose negative sign is the herald of nonclassical gasdynamics. Siloxane fluids starting from D6 and cyclic siloxanes of greater complexity, and MD3M and linear siloxanes of greater complexity are predicted to exhibit a thermodynamic region in which ? is negative and hence nonclassical wavefields are admissible. As an exemplary case, a nonclassical rarefaction shock wave propagating in fluid D6 is studied to demonstrate the possibility of using siloxane fluids in nonclassical gasdynamic applications and to experimentally verify the existence of nonclassical wavefields in the vapor phase. The sensitivity of the present results to the considered thermodynamic model of the fluid is also briefly discussed.

  15. Assessing the clarity of friction ridge impressions.

    PubMed

    Hicklin, R Austin; Buscaglia, JoAnn; Roberts, Maria Antonia

    2013-03-10

    The ability of friction ridge examiners to correctly discern and make use of the ridges and associated features in finger or palm impressions is limited by clarity. The clarity of an impression relates to the examiner's confidence that the presence, absence, and attributes of features can be correctly discerned. Despite the importance of clarity in the examination process, there have not previously been standard methods for assessing clarity in friction ridge impressions. We introduce a process for annotation, analysis, and interchange of friction ridge clarity information that can be applied to latent or exemplar impressions. This paper: (1) describes a method for evaluating the clarity of friction ridge impressions by using color-coded annotations that can be used by examiners or automated systems; (2) discusses algorithms for overall clarity metrics based on manual or automated clarity annotation; and (3) defines a method of quantifying the correspondence of clarity when comparing a pair of friction ridge images, based on clarity annotation and resulting metrics. Different uses of this approach include examiner interchange of data, quality assurance, metrics, and as an aid in automated fingerprint matching. PMID:23313600

  16. How To Achieve Better Impressions in Computer-Mediated Communication?

    ERIC Educational Resources Information Center

    Liu, Yuliang; Ginther, Dean

    This paper presents a review of the literature on impression formation in face-to-face (FtF) and computer-mediated communication (CMC) and provides impression management recommendations for CMC users in a variety of environments. The first section provides an introduction to impression formation. Factors affecting impression formation in FtF and…

  17. Impressions of the resume: The effects of applicant education, experience, and impression management

    Microsoft Academic Search

    Stephen B. Knouse

    1994-01-01

    Business persons each read a hypothetical variation of a resume arrayed in a 2 (relevant versus irrelevant education) × 2 (relevant versus irrelevant job experience) × 2 (impression management versus no impression management statements) factorial design and completed a survey on their perceptions. Results showed that relevant education produced more positive perceptions of competence, potential, and predicted salary, while relevant

  18. Intraoral digital impressions to enhance implant esthetics.

    PubMed

    Hinds, Kenneth F

    2014-09-01

    Providing an accurate soft-tissue transfer for anterior implants is not a new concept; however, it is currently an especially relevant one. There are numerous documented cases in which residual excess cement with cement-retained implant restorations was a contributing cause in periimplantitis. In 2012, Wadhwani et al reported the importance of placing the crown abutment margins supragingivally for ease of cement removal as a possible solution to address this important issue. Therefore, if placement of the crown abutment margin location is imperative, making an impression that reproduces the soft tissue is equally critical. In 1997, this author introduced the "custom impression coping" to achieve such an accurate transfer. Given the wide use of intraoral digital impressions in 2014, this discussion describes how to fabricate a "custom scan body" using that technology to replicate the transition zone in the virtual environment. PMID:25279537

  19. Methyl siloxanes in environmental matrices and human plasma/fat from both general industries and residential areas in China.

    PubMed

    Xu, Lin; Shi, Yali; Liu, Nannan; Cai, Yaqi

    2015-02-01

    We investigated human exposure to methyl siloxanes in three general industries (building, automobile, and textile industries) and residential areas in China. Usage volumes of methyl siloxanes per capita in these industries were 2-5 orders of magnitudes higher than those in residential areas. Methyl siloxane concentrations in indoor air and dust samples from industrial facilities were 1-3 orders of magnitudes higher than those in residential houses. Both cyclic (D4-D6) and linear (L5-L16) siloxanes were detected in plasma of industrial workers (1.00-252 ng/mL, detection frequencies=3.7-71%, n=528), while only cyclic compounds (D4-D6) were detected in plasma of general population (n=519) with much lower concentrations (1.10-7.50 ng/mL) and detection frequencies (1.7-3.7%). During the occupational exposure, anti-dust mask can reduce 30% of intake of cyclic siloxanes and 74% of intake of linear siloxanes, respectively. In addition, PM-10 could elevate intake of linear siloxanes. Calculated fat-plasma partition ratios of methyl siloxanes (D4-D6, L6-L11) in the present study were 5.3-241 mL/g. Linear rather than cyclic siloxanes had an apparent accumulation in abdominal fat. Population's half-lives of L8-L10 in abdominal fat of general population were approximately 1.49-1.80 years. PMID:25461047

  20. Comparison of elastomeric impression materials' thixotropic behavior.

    PubMed

    Tolidis, K; Tortopidist, D; Gerasimou, P; Theocharidou, A; Boutsiouki, C

    2013-06-01

    The improved flow characteristics of new elastomeric impression materials are significant factors in the selection ofsuitableproductsfor clinical applications. The aim of this study was to assess the thixotropic behavior and compare the flow characteristics of seven different elastomeric impression materials using a shark fin test. One polyvinylsiloxane showed the highest shark fin height values, while the newly formed vinylsiloxanether material exhibited no significant differences when compared with two polyvinylsiloxanes. One of the five polyvinylosiloxanes presented significantly lower shark fin values than all other materials. It was concluded that flow characteristics for most of the tested materials are acceptable. PMID:23888530

  1. [Digital implant impression taking - an overview].

    PubMed

    Mahl, Dominik; Glenz, Fabienne; Marinello, Carlo P

    2014-01-01

    In dentist's daily practice, intraoral scanning systems are increased. Besides scanning of prepared teeth, also implants could be scanned intraorally. This clinical report describes the step-by-step techniques to scan digitally intraoral implants with two intraoral scanners (Lava™ C.O.S., 3M Espe and the CEREC AC connected with inLab MC XL, Sirona) for generating implant suprastructures without the use of impression materials, dental stone or implant impression copings. Different workflows, possibilities and limits by scanning dental implants are demonstrated. PMID:24585419

  2. Impression Management during the Reagan Transition.

    ERIC Educational Resources Information Center

    Johnson, Karen S.

    A quantitative content analysis and a thematic analysis were made of the "Washington Post," the "New York Times,""Newsweek," and "Time" from November 4, 1980, through January 20, 1981, to examine President-elect Reagan's transition period in order to determine his impression management--the way he defined himself and his relationships with other…

  3. High temperature impression creep testing of weldments

    Microsoft Academic Search

    W. S. Gibbs; D. K. Matlock; D. L. Olson; S. H. Wang

    1985-01-01

    The impression creep test technique, a modified hot hardness test in which the time dependence of the indentor displacement correlates directly to creep properties, has been utilized to measure the localized creep properties across welded joints. High temperature creep data, as a function of position, with respect to the fusion line, were measured on an autogeneous GTA aluminum weld and

  4. Communication competence as knowledge, skill, and impression

    Microsoft Academic Search

    Brian H. Spitzberg

    1983-01-01

    In response to McCroskey's definition of competence as knowledge of appropriate behavior, distinct from skill and effectiveness, it is argued that competence should be viewed as a function of knowledge, skill, and motivation. In the proposed approach, competent communication refers to functionally effective interaction appropriate to a given relational context. These impressions of appropriateness and effectiveness are more likely when

  5. Interpersonal Teaching Style and Student Impression Formation

    ERIC Educational Resources Information Center

    Coldren, Jeffrey; Hively, Jodi

    2009-01-01

    Assuming that learning is an inherently social process, this research explores interpersonal variables that affect teaching. Specifically, does the interpersonal teaching style affect student impressions of the instructor? Eighty-five undergraduates viewed one of three ten-minute videos that portrayed either an authoritarian, authoritative, or…

  6. Biochemistry of microbial polyvinyl alcohol degradation

    Microsoft Academic Search

    Fusako Kawai; Xiaoping Hu

    2009-01-01

    Effect of minor chemical structures such as 1,2-diol content, ethylene content, tacticity, a degree of polymerization, and\\u000a a degree of saponification of the main chain on biodegradability of polyvinyl alcohol (PVA) is summarized. Most PVA-degraders\\u000a are Gram-negative bacteria belonging to the Pseudomonads and Sphingomonads, but Gram-positive bacteria also have PVA-degrading\\u000a abilities. Several examples show symbiotic degradation of PVA by different

  7. Nonlinear Dielectric Relaxation Spectra of Polyvinyl Acetate

    Microsoft Academic Search

    Takeo Furukawa; Kiyokazu Matsumoto

    1992-01-01

    The frequency spectra of the linear and third nonlinear permittivities, \\\\varepsilon1* and \\\\varepsilon3*, have been measured for polyvinyl acetate (PVAc) at temperatures above Tg. The Debye relaxation of \\\\varepsilon1* associated with the micro-Brownian motion of noncrystalline segments is found to be accompanied by the complex frequency dependence of \\\\varepsilon3* due to combined contributions from the intrinsic nonlinear dielectricity and the

  8. 40 CFR 721.9517 - Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl amino) propyl] amino]carbonyl]-2-oxo-1...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...2012-07-01 2012-07-01 false Siloxanes and silicones, de-Me, 3-[4...Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3-[4...The chemical substance identified as siloxanes and silicones, de-Me,...

  9. 40 CFR 721.9517 - Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl amino) propyl] amino]carbonyl]-2-oxo-1...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...2013-07-01 2013-07-01 false Siloxanes and silicones, de-Me, 3-[4...Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3-[4...The chemical substance identified as siloxanes and silicones, de-Me,...

  10. 40 CFR 721.9517 - Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl amino) propyl] amino]carbonyl]-2-oxo-1...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Siloxanes and silicones, de-Me, 3-[4...Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3-[4...The chemical substance identified as siloxanes and silicones, de-Me,...

  11. 40 CFR 721.9517 - Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl amino) propyl] amino]carbonyl]-2-oxo-1...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Siloxanes and silicones, de-Me, 3-[4...Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3-[4...The chemical substance identified as siloxanes and silicones, de-Me,...

  12. 40 CFR 721.9517 - Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl amino) propyl] amino]carbonyl]-2-oxo-1...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...2014-07-01 2014-07-01 false Siloxanes and silicones, de-Me, 3-[4...Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3-[4...The chemical substance identified as siloxanes and silicones, de-Me,...

  13. Formation mechanism of photo-induced nested wrinkles on siloxane-photomonomer hybrid film

    NASA Astrophysics Data System (ADS)

    Suzuki, Kazumasa; Tokudome, Yasuaki; Takahashi, Masahide

    2014-10-01

    Nested wrinkle structures, hierarchical surface wrinkles of different periodicities of sub-?m and tens-?m, have been fabricated on a siloxane-photomonomer hybrid film via a photo-induced surface polymerization of acrylamide. The formation mechanism of the nested wrinkle structures is examined based on a time-dependent structure observation and chemical composition analyses. In-situ observation of the evolving surface structure showed that sub-?m scale wrinkles first formed, subsequently the tens-?m scale ones did. In-situ FT-IR analysis indicated that the nested wrinkles formation took place along with the development of siloxane network of under layer. A cross sectional observation of the film revealed that the film was composed of three layers. FT-IR spectra of the film revealed that the surface and interior layers were polyacrylamide rich layer and siloxane-polymer rich layer, respectively. The intermediate layer formed as a diffusion layer by migration of acrylamide from interior to the surface. These three layers have different chemical compositions and therefore different mechanical characteristics, which allows the wrinkle formation. Shrinkage of siloxane-polymer interior layers, as a result of polycondensation of siloxane network, induced mechanical instabilities at interlayers, to form the nested wrinkle structures.

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

    Microsoft Academic Search

    Martin Schweigkofler; Reinhard Niessner

    1999-01-01

    Biogases such as landfill gas and sewage gas undergo a combustion process which is generating electric energy. Since several trace compounds such as siloxanes (also halogenated and sulfur compounds) are known to cause severe problems to these gas combustion engines, they are of particular interest. In this work, a new technique for sampling, identification, and quantification of siloxanes and volatile

  15. 78 FR 39256 - Polyvinyl Alcohol From Taiwan: Rescission of Antidumping Duty Administrative Review; 2012-2013

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

    ...Administration [A-583-841] Polyvinyl Alcohol From Taiwan: Rescission of Antidumping...the antidumping duty order on polyvinyl alcohol (PVA) from Taiwan for the period March...CCPC to the Department, ``Polyvinyl Alcohol from Taiwan: Withdrawal of...

  16. ANIMAL ANALOGIES IN FIRST IMPRESSIONS OF FACES

    PubMed Central

    Zebrowitz, Leslie A.; Wadlinger, Heather A.; Luevano, Victor X.; White, Benjamin M.; Xing, Cai; Zhang, Yi

    2013-01-01

    Analogies between humans and animals based on facial resemblance have a long history. We report evidence for reverse anthropomorphism and the extension of facial stereotypes to lions, foxes, and dogs. In the stereotype extension, more positive traits were attributed to animals judged more attractive than con-specifics; more childlike traits were attributed to those judged more babyfaced. In the reverse anthropomorphism, human faces with more resemblance to lions, ascertained by connectionist modeling of facial metrics, were judged more dominant, cold, and shrewd, controlling attractiveness, babyfaceness, and sex. Faces with more resemblance to Labradors were judged warmer and less shrewd. Resemblance to foxes did not predict impressions. Results for lions and dogs were consistent with trait impressions of these animals and support the species overgeneralization hypothesis that evolutionarily adaptive reactions to particular animals are overgeneralized, with people perceived to have traits associated with animals their faces resemble. Other possible explanations are discussed. PMID:25339791

  17. Adhesion of elastomeric impression materials to trays.

    PubMed

    Bindra, B; Heath, J R

    1997-01-01

    The tensile and shear adhesive bond strengths of two addition cured silicones (Provil and Express) and a polyether (Impregum) impression material to brass, poly(methylmethacrylate) and visible light-cured (VLC) tray resin were determined. Adhesive application significantly increased the bond strength; Provil and Express adhered most strongly to brass; whilst the Impregum-VLC combination produced the strongest bond. Indeed, VLC resin generated greater adhesion than acrylic resin. Exchanging the adhesives specified for each silicone material generally resulted in higher bond strengths. No correlation was established between speed of separation of the test surfaces and bond strength. For optimum clinical performance, the impression material (adhesive) tray material giving the highest bond strength should be utilized. PMID:9049922

  18. Burger or yogurt? Indulgent consumption in impression management contexts.

    PubMed

    Cheng, Yin-Hui; Huang, Molly C-J; Chuang, Shih-Chieh; Ju, Ying Rung

    2014-10-01

    We conducted three studies to investigate indulgent choice in settings with and without impression management by public-private manipulation with evaluation. Study 1 showed that the participants were less indulgent under public scrutiny due to the employment of impression management. Study 2 focused on the impression management context to test the moderate effect of self-consciousness in two impression managed contexts. Study 3 focused on context without impression management to test the moderate effects of self-awareness on choices. We found that depending on differences in primed personality, individuals tended to make choices other than those they favoured privately when anticipating that others might form impressions of them based on the decisions made. The findings of all three studies support our basic prediction that people are less indulgent under impression management and suggest that people tend to manage their impression by eating healthier (less indulgently) in public. PMID:25287306

  19. The Importance of Subtextual Impression Management and Business Faculty.

    ERIC Educational Resources Information Center

    Chaney, Lillian H.; Lyden, Julie A.

    1998-01-01

    College students (n=265) reported their impressions of business faculty's personal appearance, body language, behavior, and office appearance. Findings indicate that impression management is useful for professors who want to convey credibility, authority, and interest in students. (JOW)

  20. Concentrations and distribution of synthetic musks and siloxanes in sewage sludge of wastewater treatment plants in China.

    PubMed

    Liu, Nannan; Shi, Yali; Li, Wenhui; Xu, Lin; Cai, Yaqi

    2014-04-01

    In this study, we assessed the occurrence and distribution patterns of seven synthetic musks (SMs) and 17 siloxanes in anaerobic digested sludge samples collected at the dewatering process from 42 wastewater treatment plants (WWTPs) in China. SMs in sludge from different WWTPs exhibited similar composition profiles, and their total concentrations ranged from 47.3 ng/g to 68.2 ?g/g dry weight (dw). On average, galaxolide (HHCB, 63.8%) and tonalide (AHTN, 31.7%) accounted for 95.5% of ?SMs. The total concentrations of cyclic siloxanes ranged from siloxanes. On average, cyclic siloxanes accounted for 68% of the total siloxanes. High concentrations and detection frequencies of SMs and siloxanes in sewage sludge indicated that both of them were widely used in China. Among the sludge samples from 42 WWTPs, the concentrations of both ?SMs and ?siloxanes had considerable variations. We investigated the influence of potential factors (wastewater and sludge characteristics, the treatment capacity, serving population, and the treatment techniques of WWTPs) on the levels of target compounds in sludge, and found that SMs were significantly (p<0.05) correlated with the total organic carbon (TOC) of the sludge and the serving population of WWTP. There were also strong correlations (p<0.05) between the treatment capacity of WWTPs and cyclic siloxanes, as well as between the TOC of the sludge and linear siloxanes. In addition, the ecological risks of SMs and siloxanes in sewage sludge addressed to land application were assessed, which suggested that there was a low risk to the soil environment. PMID:24463026

  1. Otologic complications caused by hearing aid mold impression material.

    PubMed

    Lee, Dong Hoon; Cho, Hyong-Ho

    2012-08-01

    We report two extremely rare cases of otologic complications caused by hearing aid mold impression material. The symptoms of patients with retained impression material are characteristic of the length of time the impression material is retained. In case 1 had a chronic discharge and granulation tissue of the middle ear, while case 2 presented with acute pain and dizziness. The management for retained impression material may require surgical interventions, which can be safely accomplished by standard otologic techniques. PMID:21862255

  2. Impression management in the resume and its cover letter

    Microsoft Academic Search

    Stephen B. Knouse; Robert A. Giacalone; Hinda Pollard

    1988-01-01

    Eighty-one managers read application materials arrayed in a 2 (impression management versus nonimpression management cover letter) x 2 (impression management versus nonimpression management resume) x 2 (high versus low self-monitor) design and completed a survey on their perceptions. Managers rated the impression management cover letter negatively on several perceptions but positively on self-confidence. They rated the impression management resume negatively

  3. Unsupervised Footwear Impression Analysis and Retrieval from Crime Scene Data

    E-print Network

    Vetter, Thomas

    Unsupervised Footwear Impression Analysis and Retrieval from Crime Scene Data Adam Kortylewski.kortylewski,thomas.albrecht,thomas.vetter}@unibas.ch Abstract. Footwear impressions are one of the most frequently secured types of evidence at crime scenes as rigid transformations on a database with real crime scene impressions. More- over, we make our database

  4. METHOD OF POLYVINYL ALCOHOL SUBSTITUTION IN AQUEOUS MAGNETIC COLLOIDS

    E-print Network

    Paris-Sud XI, Université de

    873 METHOD OF POLYVINYL ALCOHOL SUBSTITUTION IN AQUEOUS MAGNETIC COLLOIDS D. CHANDESRIS, A substitution of the water by a polyvinyl alcohol. The resulting samples are solid and can be studied : a good ferrofluid, i. e. one which strongly counteracts the separation of the grains from the liquid

  5. Complex compound polyvinyl alcohol-titanic acid/titanium dioxide

    NASA Astrophysics Data System (ADS)

    Prosanov, I. Yu.

    2013-02-01

    A complex compound polyvinyl alcohol-titanic acid has been produced and investigated by means of IR and Raman spectroscopy, X-ray diffraction, and synchronous thermal analysis. It is claimed that it represents an interpolymeric complex of polyvinyl alcohol and hydrated titanium oxide.

  6. Occurrence of cyclic and linear siloxanes in indoor air from Albany, New York, USA, and its implications for inhalation exposure.

    PubMed

    Tran, Tri Manh; Kannan, Kurunthachalam

    2015-04-01

    Cyclic and linear siloxanes are used in a wide variety of household and consumer products. Nevertheless, very few studies have reported the occurrence of these compounds in indoor air or inhalation exposure to these compounds. In this study, five cyclic (D3-D7) and nine linear siloxanes (L3-L11) were determined in 60 indoor air samples collected in Albany, New York, USA. The mean concentrations of individual siloxanes in particulate and vapor phases ranged from <12 ?g g(-1) (for octamethyltrisiloxane [L3], decamethyltetrasiloxane [L4]) to 2420 ?g g(-1) (for decamethylcyclopentasiloxane [D5]) and from 1.05 ng m(-3) to 543 ng m(-3), respectively. The mean concentrations of individual siloxanes in combined particulate and vapor phases of bulk indoor air ranged from 1.41 ng m(-3) (for L4) to 721 ng m(-3) (for D5). Cyclic siloxanes hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), D5, dodecamethylcyclohexasiloxane (D6), and octadecamethylcycloheptasiloxane (D7) were found in all indoor air samples. The mean concentrations of total siloxanes (i.e., sum of cyclic and linear siloxanes) ranged from 249 ng m(-3) in laboratories to 6210 ng m(-3) in salons, with an overall mean concentration of 1470 ng m(-3) in bulk indoor air samples. The calculated mean daily inhalation exposure doses of total siloxanes (sum of 14 siloxanes) for infants, toddlers, children, teenagers, and adults were 3.18, 1.59, 0.76, 0.34, and 0.27 ?g/kg-bw/day, respectively. PMID:25540848

  7. Observations and impressions from lunar orbit

    NASA Technical Reports Server (NTRS)

    Mattingly, T. K.; El-Baz, F.; Laidley, R. A.

    1972-01-01

    On Apollo 16, the command module pilot made observations of particular surface features and processes to complement photographic and other remotely sensed data. Emphasis was placed on geological problems that required the extreme dynamic range and color sensitivities of the human eye; repetitive observations of varying sun angles and viewing directions; and, in some cases, on-the-scene interpretations. Visual observations and impressions recorded during the mission verified the effectiveness of the hardware and techniques used. The orbiting observer functioned both as a sensor, in otherwise inaccessible areas such as earthshine and shadows, and as a designator of potentially significant data that were acquired on the photographic record.

  8. Glucose permeable poly (dimethyl siloxane) poly ( N-isopropyl acrylamide) interpenetrating networks as ophthalmic biomaterials

    Microsoft Academic Search

    L Liu; H Sheardown

    2005-01-01

    Poly (dimethyl siloxane) (PDMS) has been widely used as a biomaterial in ophthalmic and other applications due to its good compatibility, high mechanical strength, excellent oxygen permeability and transparency. However, for use as an artificial cornea, contact lens and in other applications, modifications with hydrophilic functional groups or polymers are necessary to improve wettability for tear protein and mucin interactions

  9. Regular assembly of cage siloxanes by hydrogen bonding of dimethylsilanol groups.

    PubMed

    Sato, Naoto; Kuroda, Yoshiyuki; Abe, Takuya; Wada, Hiroaki; Shimojima, Atsushi; Kuroda, Kazuyuki

    2015-06-25

    A new class of ordered silica-based materials has been prepared by hydrogen bond-directed assembly of cage siloxanes modified with dimethylsilanol groups, providing a soft-chemical approach to crystalline silica materials with molecularly designed architectures. PMID:26063451

  10. Studies on siloxane polymers for NIR-evanescent wave absorbance sensors

    Microsoft Academic Search

    B. Zimmermann; J. Bürck; H.-J. Ache

    1997-01-01

    The properties of siloxane membranes were optimized for the application in optical sensors for monitoring nonpolar organic compounds in aqueous media. The sensing principle is based on the enrichment of these substances in a hydrophobic polysiloxane membrane and the measurement of their evanescent wave near-infrared (NIR) absorption spectra by means of a light conducting element, which is in contact with

  11. Copper-Catalyzed Electrophilic Amination of Organolithiums Mediated by Recoverable Siloxane Transfer Agents

    PubMed Central

    Nguyen, Minh H.

    2013-01-01

    The development and validation of copper-catalyzed, electrophilic amination of aryl and heteroaryl organolithiums with N,N-dialkyl -O-benzoylhydroxylamineshavebeenachievedexploitingrecoverablesiloxanetransferagents. Given the readily availability of organolithium compounds, the mild reaction conditions, the ease of product purification and the ready recovery of the siloxane transfer agents, this transformation comprises a useful tactic to access diverse aryl and heteroaryl amines. PMID:24000819

  12. Design and Lipase Catalyzed Synthesis of 4-Methylcoumarin-siloxane Hybrid Copolymers

    Microsoft Academic Search

    Mukesh K. Pandey; Amol Chandekar; Rahul Tyagi; Virinder S. Parmar; Vincent B. Tucci; Kenneth D. Smith; Phillip R. Westmoreland; Ravi Mosurkal; Jayant Kumar; Arthur C. Watterson

    2008-01-01

    Poly dimethylsiloxanes with amino end groups were copolymerized with diesters of 4-methylcoumarins enzymatically using a lipase (Candidaantarctica lipase) as a biocatalyst. In a separate synthesis, 4-methylcoumarin was also incorporated into the poly siloxanes-isophthalate copolymers by functionalization of hydroxyl groups in the isophthalate moiety. The synthesis and characterization of two sets of novel copolymers are presented. The thermal and flammability properties

  13. Hydrophobicity of Siloxane Surfaces in Smectites as Revealed by Aromatic Hydrocarbon Adsorption from Water

    Microsoft Academic Search

    W. F. Jaynes; S. A. BOYD

    1991-01-01

    The nature of the siloxane surface in smectites was investigated by measuring the adsorption of aromatic hydrocarbons from water by organo-clays. The organo-clays were prepared by replacing the hydrophilic, inorganic exchange cations of a series of smectites with the small, hydrophobic organic cation, trimethylphenylammonium (TMPA). Smectites with a range in charge densities were used that resulted in different TMPA contents

  14. Hydrogen-Bond Basic Siloxane Phosphonate Polymers for Surface Acoustic Wave (Saw) Sensors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A surface acoustic wave (SAW) sensor coated with a novel hydrogen-bond basic siloxane phosphonate SAW polymer gave excellent initial response and long-term performance when tested against phenol vapor and compared with polyethyleneimine (PEI), a conventional hydrogent-bond basic SAW polymer....

  15. Cyclic siloxanes in air, including identification of high levels in Chicago and distinct diurnal variation

    PubMed Central

    Yucuis, Rachel A.; Stanier, Charles O.; Hornbuckle, Keri C.

    2014-01-01

    The organosilicon compounds octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) are high production volume chemicals that are widely used in household goods and personal care products. Due to their prevalence and chemical characteristics, cyclic siloxanes are being assessed as possible persistent organic pollutants. D4, D5, and D6 were measured in indoor and outdoor air to quantify and compare siloxane concentrations and compound ratios depending on location type. Indoor air samples had a median concentration of 2200 ng m?3 for the sum of D4, D5, and D6. Outdoor sampling locations included downtown Chicago, Cedar Rapids, IA, and West Branch, IA, and had median sum siloxane levels of 280, 73, and 29 ng m?3 respectively. A diurnal trend is apparent in the samples taken in downtown Chicago. Nighttime samples had a median 2.7 times higher on average than daytime samples, which is due, in part, to the fluctuations of the planetary boundary layer. D5 was the dominant siloxane in both indoor and outdoor air. Ratios of D5 to D4 averaged 91 and 3.2 for indoor and outdoor air respectively. PMID:23541357

  16. DOI: 10.1002/adfm.200700086 A Self-Healing Poly(Dimethyl Siloxane) Elastomer**

    E-print Network

    Sottos, Nancy R.

    DOI: 10.1002/adfm.200700086 A Self-Healing Poly(Dimethyl Siloxane) Elastomer** By Michael W. Keller, Scott R. White, and Nancy R. Sottos* 1. Introduction Self-healing polymers and composites and dynamic loading conditions.[1­8] Most self-healing research has focused on the autonomic repair of brittle

  17. Impression Management in Survey Responding: Easier for Collectivists or Individualists?

    PubMed Central

    Riemer, Hila; Shavitt, Sharon

    2012-01-01

    Three experiments indicate that when individualists and collectivists engage in impression management on self-reports, they do so through different psychological mechanism s. Collectivists do so through a relatively automatic process. Thus, they can impression manage even when cognitively busy. Individualists impression manage through a more effortful process. Therefore, they can do so only when the situation permits effortful processing. These findings highlight distinct conditions under which social norms may influence consumer self-reports across cultures. PMID:23175618

  18. 21 CFR 872.6880 - Preformed impression tray.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...6880 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6880 Preformed impression tray. (a)...

  19. Characterization of full-scale carbon contactors for siloxane removal from biogas using online Fourier transform infrared spectroscopy.

    PubMed

    Hepburn, C A; Martin, B D; Simms, N; McAdam, E J

    2015-01-01

    In this study, online Fourier transform infrared (FTIR) spectroscopy has been used to generate the first comprehensive characterization of full-scale carbon contactors for siloxane removal from biogas. Using FTIR, two clear operational regions within the exhaustion cycle were evidenced: an initial period of pseudo-steady state where the outlet siloxane concentration was consistently below the proposed siloxane limits; and a second period characterized by a progressive rise in outlet siloxane concentration during and after breakthrough. Due to the sharp breakthrough front identified, existing detection methods (which comprise field sampling coupled with laboratory-based chromatographic determination) are insufficiently responsive to define breakthrough, thus carbon contactors currently remain in service while providing limited protection to the combined heat and power engine. Integration of the exhaustion cycle to breakthrough identified average specific media capacities of 8.5-21.5 gsiloxane [Formula: see text], which are lower than that has been reported for vapour phase granular activated carbon (GAC). Further speciation of the biogas phase identified co-separation of organic compounds (alkanes and aromatics), which will inevitably reduce siloxane capacity. However, comparison of the five full-scale contactors identified that greater media capacity was accessible through operating contactors at velocities sufficient to diminish axial dispersion effects. In addition to enabling significant insight into gas phase GAC contactors, the use of FTIR for online control of GAC for siloxane removal is also presented. PMID:25413112

  20. Contribution of siloxanes to COD loading at wastewater treatment plants: phase transfer, removal, and fate at different treatment units.

    PubMed

    Surita, Sharon C; Tansel, Berrin

    2015-03-01

    Cyclic volatile methylsiloxanes (cVMSs) are entering to waste stream in increasing quantities due to their increasing use in personal care products (i.e., shampoos, creams). The cVMSs have high vapor pressures and low solubilities and are mostly transferred into the gaseous phase via volatilization; however, some are sorbed onto biosolids. The purpose of this study was to track and estimate the phase transfer (water, solids, gas), fate, and contribution to COD loading of selected siloxanes (D4, D5 and D6) which are the most commonly found cVMSs in the wastewater systems. Removal efficiencies of the wastewater treatment units were evaluated based on the partitioning characteristics of the cVMSs in gas, liquid, and biosolids phases. The contributions of the siloxanes present in the influent and effluent were estimated in terms of COD levels based on the theoretical oxygen demand (ThOD) of the siloxanes. Siloxanes constitute approximately 39 and 0.001mgL(-1) of the COD in the influents and effluent. Oxidation systems showed higher removal efficiencies based COD loading in comparison to the removal efficiencies achieved aeration tanks and filtration systems. Treatment systems effectively remove the siloxanes from the aqueous phase with over 94% efficiency. About 50% of the siloxanes entering to the wastewater treatment plant accumulate in biosolids. PMID:25528947

  1. Polyvinyl alcohol cross-linked with two aldehydes

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.; Rieker, L. L.; Hsu, L. C.; Manzo, M. A. (inventors)

    1982-01-01

    A film forming polyvinyl alcohol resin is admixed, in aqueous solution, with a dialdehyde crosslinking agent which is capable of crosslinking the polyvinyl alcohol resin and a water soluble acid aldehyde containing a reactive aldehyde group capable of reacting with hydroxyl groups in the polyvinyl alcohol resin and an ionizable acid hydrogen atom. The dialdehyde is present in an amount sufficient to react with from 1 to 20% by weight of the theoretical amount required to react with all of the hydroxyl groups of the polyvinyl alcohol. The amount of acid aldehyde is from 1 to 50% by weight, same basis, and is sufficient to reduce the pH of the aqueous admixture to 5 or less. The admixture is then formed into a desired physical shape, such as by casting a sheet or film, and the shaped material is then heated to simultaneously dry and crosslink the article.

  2. Survey of Cyclic and Linear Siloxanes in Sediment from the Songhua River and in Sewage Sludge from Wastewater Treatment Plants, Northeastern China

    Microsoft Academic Search

    Zifeng ZhangHong; Hong Qi; Nanqi Ren; Yifan Li; Dawen Gao; Kurunthachalam Kannan

    2011-01-01

    Siloxanes are used in a wide range of industrial applications, such as fuel additives, automotive polishes and waxes, and\\u000a antifoaming agents, as well as in personal care products and biomedical devices. Despite the potential for environmental occurrence,\\u000a few studies have reported sources and pathways of siloxanes in the environment. In this study, we determined concentrations\\u000a of four cyclic siloxanes, namely,

  3. Non-toxic liquid scintillators with high light output based on phenyl-substituted siloxanes

    NASA Astrophysics Data System (ADS)

    Dalla Palma, M.; Carturan, S. M.; Degerlier, M.; Marchi, T.; Cinausero, M.; Gramegna, F.; Quaranta, A.

    2015-04-01

    The work describes the development of a new class of liquid scintillators based on polysiloxane liquid compounds. These materials are characterized by low toxicity, chemical inertness, very low volatility and low flammability, allowing their use without concerns even at high temperatures in vacuum. In this view different polysiloxane based liquids have been tested, with variable content and distribution of phenyl lateral substituents and added with suitable dyes, namely 2,5-diphenyloxazole (PPO) and Lumogen Violet (LV). Absorption and fluorescence spectroscopy have been used in order to study the emission feature of the various compounds and to investigate the spectral matching between siloxane solvents and dissolved primary dyes. Scintillation efficiency towards 60Co and 137Cs gamma rays, relative to commercial liquid scintillator (EJ-309), has been measured and the results have been related to the energy transfer and energy migration mechanism from monomer and excimer forming sites in liquid siloxanes.

  4. Star-shape Poly(vinylmethyl-co-dimethyl)siloxanes with Carbosilane Core - Synthesis and Application

    NASA Astrophysics Data System (ADS)

    Kowalewska, Anna; Delczyk, Bogumi?a

    New polymeric supports, that can be used for preparation of novel catalytic systems, were obtained by grafting poly(vinylmethyl-co-dimethyl)siloxane arms onto multifunctional carbosilane moieties which belong to the class of exceptionally sterically hindered tris(silyl)methanes (TSi). Three types of TSi molecules were applied: 3-functional HC(SiMe2Br)3 (type A), 9-functional HC[SiMe2(CH2)5-C (SiMe2Br)3]3 (type B) and 4-functional TSi-derivative [SiMe2C(SiMe2Br)2]2 (type C). The periphery-functionalized carbosilane-siloxane materials offer uniformly distributed and accessible sites for coordination of active catalytic species. New catalytic systems were thus prepared by coordination of platinum to vinyl moieties of the reported polymers, and used in hydrosilylation of vinyltrimethylsilane with 1,1,3,3-tetramethyldisiloxane.

  5. INTRODUCTION Insects display an impressive diversity of acoustic sensory organs

    E-print Network

    Yack, Jayne E.

    roles in detecting predators and prey, and in social communication. Insect tympanal hearing organs share3533 INTRODUCTION Insects display an impressive diversity of acoustic sensory organs that play key, 2008). This functional diversity is achieved by impressive morphological diversity. Insect tympanal

  6. Coping With Stereotype Threat: Denial as an Impression Management Strategy

    Microsoft Academic Search

    William von Hippel; Courtney von Hippel; Leanne Conway; Kristopher J. Preacher; Jonathan W. Schooler; Gabriel A. Radvansky

    2005-01-01

    Four experiments tested the hypothesis that people who are concerned with impression management cope with stereotype threat through denial. Consistent with this hypothesis, temporary employees threatened by a stereotype of incompetence (Study 1) and hostel-dwelling older adults (Study 2) were more likely to deny incompetence if they were high in impression management. African Americans (Study 3) showed a similar pattern

  7. Gas separation properties of hybrid imide–siloxane copolymers with various silica contents

    Microsoft Academic Search

    Monique Smaihi; Jean-Christophe Schrotter; Chantal Lesimple; Isabelle Prevost; Christian Guizard

    1999-01-01

    Hybrid polyimide–siloxane copolymers containing different proportion of silica have been prepared by polycondensation, imidisation and sol–gel coreaction of pyromellitic dianhydride, aminoalkoxysilane and tetramethoxysilane. Two types of aminoalkoxysilane (aminopropyltrimethoxysilane and aminopropylmethyldiethoxysilane) able to provide a bonding between the inorganic and the organic phase were used. Materials obtained were characterized by various techniques (thermogravimetric analysis, infrared spectrometry and 29Si NMR) in order

  8. Ferroelectric LC-siloxanes with applicability for non-linear optics

    SciTech Connect

    Schulz-Hanke, W.; Zentel, R. [Universitaet Mainz (Germany)

    1996-10-01

    We present new chiral liquid crystalline low molar mass compounds, siloxane oligomers and polymers with strong donor and acceptor groups perpendicular to the mesogene axis, which are useful candidates for application for second order nonlinear optical effects. The influence of the chiral NLO-chromophore on the liquid crystalline and ferroelectric properties of mixtures with ferroelectric oligomers are studied. The noncentrosymmetric chiral S{sub c}-phase is retained up to 70 mol% of the chiral chromophore.

  9. Novel approach to fabricate porous gelatin–siloxane hybrids for bone tissue engineering

    Microsoft Academic Search

    Lei Ren; Kanji Tsuru; Satoshi Hayakawa; Akiyoshi Osaka

    2002-01-01

    Porous and bioactive gelatin–siloxane hybrids were successfully synthesized by using a combined sol–gel processing, post-gelation soaking, and freeze-drying process to provide a novel kind of materials in the developments and optimization of bone tissue engineering. The pore sizes of the hybrids can be well controlled by varying the freezing temperature. The scaffolds were soaked in a simulated body fluid (SBF)

  10. Elaboration of low shrinkage mullite by active filler controlled pyrolysis of siloxanes

    Microsoft Academic Search

    Thibaut Michalet; Michel Parlier; Franck Beclin; Richard Duclos; Jacques Crampon

    2002-01-01

    The active filler controlled pyrolysis of polymers has been used to synthesize mullite from Al2O3-filled, Al-filled and Al\\/Al2O3-filled siloxanes. Due to the presence of transition alumina and to a finer scale of mixing of the mullite precursors provided from active Al-filler, the beginning of mullitization temperature was lowered in the two last systems (1200–1250°C) in comparison to the first one

  11. Perfluorocyclobutane Aromatic Polyethers. Synthesis and Characterization of New Siloxane-Containing Fluoropolymers †

    Microsoft Academic Search

    1996-01-01

    The synthesis and characterization of siloxane-containing perfluorocyclobutane (PFCB) aromatic polyethers, a new class of fluorosiloxane polymers possessing a well-defined linear structure of alternating disiloxanyl-p-phenylene (cis\\/trans)-1,2-disubstituted perfluorocyclobutyl ether linkages with known fluoroolefin end groups, is described. The unexpected formation of an aryl Grignard reagent from 4-((trifluorovinyl)oxy)bromobenzene (2) allowed for the high-yield synthesis of 4-((trifluorovinyl)oxy)- phenyldimethylsilane (3) which was dehydrogenatively hydrolyzed in

  12. Imide-siloxane block copolymer\\/silica hybrid membranes: preparation, characterization and gas separation properties

    Microsoft Academic Search

    Ho Bum Park; Jang Ki Kim; Sang Yong Nam; Young Moo Lee

    2003-01-01

    Imide-siloxane block copolymer\\/silica hybrid membranes with covalent bonds were prepared via sol–gel reaction. The structural informations of these hybrid membranes were obtained by using Fourier transform-infrared spectrometry (FT-IR), 29Si nuclear magnetic resonance (29Si NMR), XPS and thermogravimetric analysis (TGA). The gas separation properties of the hybrid membranes were also investigated in terms of organosiloxane (PDMS) or silica content at various

  13. Nuclear magnetic resonance techniques for the structural characterization of siloxane–oxide hybrid materials

    Microsoft Academic Search

    Florence Babonneau; Jocelyne Maquet

    2000-01-01

    The objective of this paper is to discuss the appropriateness of various solution and solid state NMR techniques to describe structural aspects of siloxane–oxide hybrid systems prepared by sol-gel processes. Co-hydrolysis of organosilanes and metallic alkoxides can promote either self-condensation or co-condensation reactions between the different precursors, and this will control the structural homogeneity of the final network. Solution state

  14. Inhibition of Candida   albicans Biofilm Formation by Antimycotics Released from Modified Polydimethyl Siloxane

    Microsoft Academic Search

    Kristof De Prijck; Nele De Smet; Kris Honraet; Steven Christiaen; Tom Coenye; Etienne Schacht; Hans J. Nelis

    2010-01-01

    Unlike various disinfectants, antifungals have not been commonly incorporated so far in medical devices, such as catheters\\u000a or prostheses, to prevent biofilm formation by Candida spp. In the present study, five antimycotics were added to polydimethyl siloxane (PDMS) disks via admixture (nystatin) or\\u000a impregnation (trimethylsilyl-nystatin (TMS-nystatin), miconazole, tea tree oil (TTO), zinc pyrithione). Nystatin-medicated\\u000a PDMS disks exhibited a concentration-dependent inhibitory

  15. A Paradigm shift in the concept for making dental impressions

    PubMed Central

    Nayar, Sanjna; Mahadevan, R.

    2015-01-01

    Digital dental impression is a revolutionary technological advancement that so surpasses the accuracy and efficiency of former techniques for obtaining replicas of prepared teeth for the purpose of fabricating restorations that its adoption by dentists is rapidly eclipsing the use of elastomeric impression materials. The ultimate goals of dentists dedicated to quality restorative dentistry are to make their treatment of patients as accurate, stressless, and efficient as possible. By elimination of the everyday problems described above, there is no question that the significant advantages of digital impressions will make intraoral digital scanning standard procedure in most dental offices within the next several years. Furthermore, digital impressions have proven to reduce remakes and returns, as well as increase overall efficiency. The patient also benefits by being provided a far more positive experience. Finally, through the use of digital impression making, it has been determined that laboratory products become more consistent and require less chair time at insertion. PMID:26015714

  16. The effect of amphiphilic siloxane oligomers on fibroblast and keratinocyte proliferation and apoptosis.

    PubMed

    Lynam, Emily C; Xie, Yan; Loli, Bree; Dargaville, Tim R; Leavesley, David I; George, Graeme A; Upton, Zee

    2010-11-01

    The formation of hypertrophic scars (HSF) is a frequent medical outcome of wound repair and often requires further therapy with treatments such as silicone gel sheets (SGS) or apoptosis-inducing agents, including bleomycin. Although widely used, knowledge regarding SGS and their mode of action is limited. Preliminary research has shown that small amounts of amphiphilic silicone present in SGS have the ability to move into skin during treatment. We demonstrate herein that a commercially available analogue of these amphiphilic siloxane species, the rake copolymer GP226, decreases collagen synthesis on exposure to cultures of fibroblasts derived from HSF. By size exclusion chromatography, GP226 was found to be a mixture of siloxane species, containing five fractions of different molecular weight. By studies of collagen production, cell viability and proliferation, it was revealed that a low molecular weight fraction (fraction IV) was the most active, reducing the number of viable cells present after treatment and thereby reducing collagen production as a result. On exposure of fraction IV to human keratinocytes, viability and proliferation were also significantly affected. HSF undergoing apoptosis after application of fraction IV were also detected via real-time microscopy and by using the TUNEL assay. Taken together, these data suggests that these amphiphilic siloxanes could be potential non-invasive substitutes to apoptotic-inducing chemical agents that are currently used as scar treatments. PMID:20725963

  17. Anisotropic polyvinyl alcohol hydrogel for cardiovascular applications.

    PubMed

    Millon, L E; Mohammadi, H; Wan, W K

    2006-11-01

    Polyvinyl alcohol (PVA) is a hydrophilic polymer with various characteristics desired for biomedical applications and can be transformed into a solid hydrogel by physical crosslinking, using a low-temperature thermal cycling process. As with most polymeric materials, the mechanical properties of the resultant PVA are isotropic, as oppose to most soft tissues, which are anisotropic. The objective of this research is to develop a PVA-based hydrogel that not only mimics the nonlinear mechanical properties displayed by cardiovascular tissues, but also their anisotropic behavior. By applying a controlled strain to the PVA samples, while undergoing low-temperature thermal cycling, we were able to create oriented mechanical properties in PVA hydrogels. The oriented stress-strain properties of porcine aorta were matched simultaneously by a PVA hydrogel prepared (10% PVA, cycle 3, 75% initial strain). This novel technique allows the controlled introduction of anisotropy to PVA hydrogel, and gives a broad range of control of its mechanical properties, for specific medical device applications. PMID:16680682

  18. Preparation and properties of polyvinyl alcohol microspheres

    SciTech Connect

    Campbell, J.H.; Grens, J.Z.; Poco, J.F.; Ives, B.H.

    1986-06-01

    Polyvinyl alcohol (PVA) microspheres, having a size range of approx.150- to 250-..mu..m diameter with 1- to 5-..mu..m wall thickness, have been fabricated using a solution droplet technique. The spheres were developed for possible use on the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program. PVA, a polymer chosen based on earlier survey work carried out at KMS Fusion, Inc., has good strength, low hydrogen permeability, is optically transparent, and water soluble. The latter property makes it safe and easy to use in our droplet generator system. A unique dual-orifice droplet generator was used to prepare the spheres. The droplet generator operating conditions and the column processing parameters were chosen using results from our 1-D model calculations as a guide. The polymer microsphere model is an extension of the model we developed to support the glass sphere production. After preparation, the spheres were physically characterized for surface quality, sphericity, wall thickness (and uniformity), and size. We also determined the buckling pressure for both uncoated and CH-coated spheres. Radiation stability to beta decay (from tritium) was evaluated by exposing the spheres to a 7-keV electron beam. The results from these and other physical property measurements are presented in this report.

  19. Polyvinyl acetate-based film coatings.

    PubMed

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

    2013-12-01

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

  20. Synthesis and characterization of novel polysiloxanes. I. Telechelic cyanate esters. II. Hindered alkyl siloxanes

    NASA Astrophysics Data System (ADS)

    Fu, Zhidong

    Two aspects of novel polysiloxane chemistry have been explored in this work: (1) the synthesis and characterization of polysiloxanes functionalized with terminal cyanate ester groups for use as low flammability impact modifiers for commercial phenolic cyanate ester resins (CERs) and (2) the synthesis and characterization of polydiethylsiloxane and polycyclotetramethylenesiloxane. CERs have been proposed as a potentially useful matrix material for commercial aircraft manufacture. However, commercial CERs do not currently have the appropriate fracture toughness for practical applications. Prior studies have shown that siloxanes offer excellent flame suppression and can improve the CERs impact properties. In this work, a series of new siloxanes terminated with cyanate-reactive groups, including bis[1,3-(4--cyanatophenyl)]-1,1,3,3-tetramethyldisiloxane (11), alpha,o-(4-cyanatophenyl) oligodimethylsiloxane (12), and alpha,o-(4-cyanatophenyl) oligo(dimethyl- co-diphenylsiloxane) (13), have been synthesized from corresponding diphenols. The intermediates and products were characterized by 1H NMR, 13C NMR, FTIR, GC-MS, and GPC. To synthesize the diphenols, a new route to synthesize disiloxane terminated with THP protected diphenols (dimer) was established. The synthesized dimer was used to equilibrate with D4 and/or D4'' to make desired siloxane oligomers. The mechanism of the equilibration of the dimer with D4 were studied. The synthesized CER monomers were polymerized by a cyclotrimerization reaction. The cured compound 11 is a brittle solid with Tg of 274°C. The cured 12 (oligodimethyl-siloxane) and 13 (oligodimethylsiloxane- co-diphenylsiloxane) are elastomers with Tg of -110°C and -8°C, respectively. The curing processes and intermediates were studied by dynamic and isothermal differential scanning calorimetry, GPC, IR and 13C NMR. The synthesized CER monomers were used as impact modifiers to blend and co-cure with the commercial CERs, Primaset PT-30. SEM shows that the cured blends of 12 and 13 with PT-30 are multiphase while the cured blend of 11 with PT-30 has no phase separation. In the second part of this work, the synthetic methods for preparing polydiethylsiloxane (PDES) and polycyclotetramethylenesiloxane were explored by both anionic and cationic ring-opening polymerization and by condensation of hydroxyl end-groups in alpha,o-dihydroxy terminated siloxanes. The intermediates and products were characterized by GPC, IR GC-MS and 1H NMR. The process of polycondensation of PDES was followed by GPC and IR.

  1. Trigeminal neuralgia secondary to basilar impression: A case report

    PubMed Central

    de Almeida Holanda, Maurus Marques; Pereira Neto, Normando Guedes; de Moura Peixoto, Gustavo; Pinheiro Santos, Rayan Haquim

    2015-01-01

    We report a rare case of trigeminal neuralgia. A 23-year-old woman with a history of 1 year of typical trigeminal neuralgia manifested the characteristics of basilar impression. Magnetic resonance imaging (MRI) demonstrated basilar impression, deformity of the posterior fossa with asymmetry of petrous bone, and compression of medulla oblongata in the topography of the odontoid apophysis. The operation was performed through a suboccipital craniectomy. The neuralgia disappeared after surgery and remains completely resolved until today. This is the second reported case of trigeminal neuralgia in a patient with basilar impression in Brazil. PMID:25972713

  2. Development of on-line FTIR spectroscopy for siloxane detection in biogas to enhance carbon contactor management.

    PubMed

    Hepburn, C A; Vale, P; Brown, A S; Simms, N J; McAdam, E J

    2015-08-15

    Activated carbon filters are used to limit engine damage by siloxanes when biogas is utilised to provide electricity. However, carbon filter siloxane removal performance is poorly understood as until recently, it had not been possible to measure siloxanes on-line. In this study, on-line Fourier Transform Infrared (FTIR) spectroscopy was developed to measure siloxane concentration in real biogas both upstream (86.1-157.5mgm(-3)) and downstream (2.2-4.3mgm(-3)) of activated carbon filters. The FTIR provided reasonable precision upstream of the carbon vessel with a root mean square error of 10% using partial least squares analysis. However, positive interference from volatile organic carbons was observed in downstream gas measurements limiting precision at the outlet to an RMSE of 1.5mgm(-3) (47.8%). Importantly, a limit of detection of 3.2mgm(-3) was identified which is below the recommended siloxane limit and evidences the applicability of on-line FTIR for this application. PMID:25966392

  3. Replication techniques with new dental impression materials in combination with different negative impression materials.

    PubMed

    Pameijer, C H

    1979-01-01

    New materials and new techniques have enabled the fabrication of more reliable and more accurate replicas. Not only is the reproduction of detail of importance, but the expertise required from the operator and the time involved to produce a replica are considered key factors. For various reasons a reliable and reproducible replication technique for scanning electron microscopy offers many advantages. Recently a new dental precision impression material has been introduced, which in combination with low viscosity resins has produced superior results over other techniques. This combination processed by means of a centrifugal casting machine has produced replicas which could easily be compared to a standard test die at magnifications up to 3000 X. More in depth testing will have to be performed to establish whether these materials can be universally applied to a broad spectrum of replication problems. The combination Reprosil/Spurr low viscosity imbedding medium yielded replicas of high quality which can be made with simple equipment and without possessing special skills. Centrifugation of the positive replication material into the negative impression virtually eliminated the entrapment of airbubbles. PMID:392716

  4. 77 FR 14342 - Polyvinyl Alcohol From Taiwan: Correction to Notice of Opportunity To Request Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ...A-583-841] Polyvinyl Alcohol From Taiwan: Correction...Request Administrative Review AGENCY: Import Administration...request administrative review of the antidumping duty order on polyvinyl alcohol from Taiwan. See Antidumping...Request Administrative Review, 77 FR 12559...

  5. 68 FR 19736 - Medical Devices; Exemption From Premarket Notification; Class II Devices; Optical Impression...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2003-04-22

    ...follows: Sec. 872.3661 Optical Impression Systems for CAD/CAM. (a) Identification. An optical impression system for computer...scanner, or equivalent type of sensor and a computer with software...Controls Guidance Document: Optical Impression Systems for...

  6. Electronic evaluation for video commercials by impression index.

    PubMed

    Kong, Wanzeng; Zhao, Xinxin; Hu, Sanqing; Vecchiato, Giovanni; Babiloni, Fabio

    2013-12-01

    How to evaluate the effect of commercials is significantly important in neuromarketing. In this paper, we proposed an electronic way to evaluate the influence of video commercials on consumers by impression index. The impression index combines both the memorization and attention index during consumers observing video commercials by tracking the EEG activity. It extracts features from scalp EEG to evaluate the effectiveness of video commercials in terms of time-frequency-space domain. And, the general global field power was used as an impression index for evaluation of video commercial scenes as time series. Results of experiment demonstrate that the proposed approach is able to track variations of the cerebral activity related to cognitive task such as observing video commercials, and help to judge whether the scene in video commercials is impressive or not by EEG signals. PMID:24427225

  7. [Impressions about responses arising from a sense of unwanted transparency].

    PubMed

    Tabata, Naoya

    2011-02-01

    The sense of unwanted transparency is the feeling that another person seemingly notices something about us that we would rather conceal. Two experiments were conducted to investigate impressions about responses arising from the sense of unwanted transparency. In Study 1, observers were asked to watch the videotape recorded in Tabata (2009) and judge the participants' responses arising from the sense of unwanted transparency. In Study 2, based on Tabata (2009), both verbal responses and nonverbal responses that were characteristic in arousing the sense of unwanted transparency were manipulated in the videotaped conversation. Participants were asked to watch the videotape and judge the confederate's impressions. The results indicated that unnatural impressions were heightened by nonverbal responses such as longer silences, averting the gaze, and increased self-touching. This suggests that these responses arising from the sense of unwanted transparency may produce a self-fulfilling prophecy. However, seemingly deceptive verbal responses were only related to the dubious impressions of the statements. PMID:21400867

  8. Poly(vinyl alcohol) (PVA)/sulfonated polyhedral oligosilsesquioxane (sPOSS) hybrid membranes

    E-print Network

    Mather, Patrick T.

    Poly(vinyl alcohol) (PVA)/sulfonated polyhedral oligosilsesquioxane (sPOSS) hybrid membranes/inorganic hybrid membranes based on poly(vinyl alcohol) (PVA) and sulfonated polyhedral oligosilsesquioxane (s membrane. Copyright # 2007 John Wiley & Sons, Ltd. KEYWORDS: poly(vinyl alcohol) (PVA); sulfonated

  9. Impressions of Danger Influence Impressions of People: An Evolutionary Perspective on Individual and Collective Cognition

    PubMed Central

    Schaller, Mark; Faulkner, Jason; Park, Justin H.; Neuberg, Steven L.; Kenrick, Douglas T.

    2011-01-01

    An evolutionary approach to social cognition yields novel hypotheses about the perception of people belonging to specific kinds of social categories. These implications are illustrated by empirical results linking the perceived threat of physical injury to stereotypical impressions of outgroups. We review a set of studies revealing several ways in which threat-connoting cues influence perceptions of ethnic outgroups and the individuals who belong to those outgroups. We also present new results that suggest additional implications of evolved danger-avoidance mechanisms on interpersonal communication and the persistence of cultural-level stereotypes about ethnic outgroups. The conceptual utility of an evolutionary approach is further illustrated by a parallel line of research linking the threat of disease to additional kinds of social perceptions and behaviors. Evolved danger-avoidance mechanisms appear to contribute in diverse ways to individual-level cognitive processes, as well as to culturally-shared collective beliefs. PMID:21874126

  10. Semipermeable thin-film membranes comprising siloxane, alkoxysilyl and aryloxysilyl oligomers and copolymers

    DOEpatents

    Babcock, Walter C. (Bend, OR); Friesen, Dwayne T. (Bend, OR)

    1988-01-01

    Novel semiperimeable membranes and thin film composite (TFC) gas separation membranes useful in the separation of oxygen, nitrogen, hydrogen, water vapor, methane, carbon dioxide, hydrogen sulfide, lower hydrocarbons, and other gases are disclosed. The novel semipermeable membranes comprise the polycondensation reaction product of two complementary polyfunctional compounds, each having at least two functional groups that are mutually reactive in a condensation polymerization reaction, and at least one of which is selected from siloxanes, alkoxsilyls and aryloxysilyls. The TFC membrane comprises a microporous polymeric support, the surface of which has the novel semipermeable film formed thereon, preferably by interfacial polymerization.

  11. Dynamic-mechanical and differential scanning calorimetry measurements on crosslinked poly(ester-siloxane)-urethanes

    Microsoft Academic Search

    S Ioan; G Grigorescu; A Stanciu

    2001-01-01

    Various crosslinked poly(ester-siloxane)-urethanes containing hard and soft segments, were prepared by a one-step melting\\/polyaddition. Thus, soft sequences based on poly(ethylene glycol adipate)diol (PEGA) or poly(diethylene glycol adipate)diol (PDEGA) as ester components, ?,?-poly(dimethylsiloxane)diol (PDMS) and\\/or polybutadienediol (PBD), were built. The hard segments were composed from diglycerin maleate tetrol (DGMA) and two aromatic diisocyanates, 4,4?-diphenylmethane diisocyanate (MDI) and 2,4-tolylene diisocyanate (TDI). Dynamic

  12. An experimental and modeling study of the thermal decomposition of siloxanes on alumina

    NASA Astrophysics Data System (ADS)

    Sonoc, Alexandru Catalin

    Siloxanes are contaminants in biogas produced at wastewater treatment plants and landfills. Siloxanes need to be removed to below 0.01 ppm (vol/vol) Si equivalent before biogas can be used as a fuel in solid oxide fuel cells without damaging them. In engines, the tolerance is no higher than 9.1 ppm (vol/vol) Si equivalent. Thermal decomposition in a packed bed of gamma alumina is a method that can remove siloxanes to the requisite tolerances. The kinetics of the decomposition reaction have not been previously studied and a kinetic model is necessary to design adsorption beds. Experiments with synthetic biogas and packed beds of activated gamma alumina were conducted to provide data to which kinetic models were fitted. The synthetic biogas used was a mixture of carbon dioxide and methane contaminated with octamethylcyclotetrasiloxane (D4) at concentrations between 32.3 and 72.7 ppm (vol/vol) Si equivalent. The alumina mass, contact times, and temperatures investigated were 0.0700 g, 5.0 to 8.0 ms, and 307 to 384 °C, respectively. The experiments consisted of exposing a heated bed of alumina, initially free of siloxanes, to a stream of synthetic biogas of constant D4 concentration and monitoring the bed exit D4 concentration. Eleven out of the twelve breakthrough curves obtained were adequately predicted by a model that assumed a first order surface reaction, shrinking core particle kinetics, and plug flow in the bed. There were no statistically significant correlations between quality of fit (sum of weighted squares residuals) and concentration, contact time, or temperature in these eleven experiments. The model was not adequate in predicting the breakthrough curve from the experiment at 307 °C and thus should only be used to predict breakthrough curves at temperatures between 333 and 384 °C. The estimated model parameters were 2.10 for intraparticle tortuosity, 406,000 m3?m -2?s-1 for Arrhenius pre-exponential factor, and 81.4 kJ?mor-1 for activation energy.

  13. Preparation and properties of halogen-free flame retardant epoxy resins with phosphorus-containing siloxanes

    Microsoft Academic Search

    Jiapei Ding; Zhiqiang Tao; Xiaobiao Zuo; Lin Fan; Shiyong Yang

    2009-01-01

    Novel epoxy resin modifiers, DOPO–TMDS and DOPO–DMDP were synthesized by addition reaction of divinylsiloxane with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide\\u000a (DOPO). Halogen-free flame retardant epoxy resins were obtained through modification of o-cresol novolac epoxy resin cured by phenol novolac resin using DOPO–TMDS and DOPO–DMDP which were characterized by 1H NMR, 13C NMR, 31P NMR and FT-IR measurements. Effects of the phosphorus-containing siloxanes on thermal

  14. Synthesis and hydrosilation of multi-vinyl branched siloxane for self-healing system

    Microsoft Academic Search

    Xiao Yun Fu; Zheng Ping Fang; Hai Tang Yang; Li Fang Tong

    2008-01-01

    In this work, the preparation of ?,?-dichloride-terminated multi-vinyl branched siloxane 1 (yield: 57.1%) used for self-healing polymer composites were synthesized via ring-opening of 1,3,5,7-tetravinyl-1,3,5,7-tetramethyl-cyclotetrasiloxane (D4Vi) in the presence of vinylmethydichlorosilane (VM–32). 1 was hydrogenated by aluminum lithium hydride (LiAlH4) to get self-healing monomer 2 (yield: 79.8%) which contained both Si–H bonds and Si–vinyl bonds. Then hydrosilation occurred between these two

  15. Lifting bloody footwear impressions using alginate casts followed by chemical enhancement.

    PubMed

    Wiesner, Sarena; Izraeli, Elad; Shor, Yaron; Domb, Avi

    2013-05-01

    A method for lifting bloody footwear impressions using alginate casts and enhancing the lifted impressions with amido black is presented. On rough or dark substrates, background interferences may conceal significant details of footwear impressions. Illumination with alternative light sources and chemically enhancing the bloody footwear impressions may reveal additional details, but sometimes, lifting footwear impressions prior to enhancing is the only way to expose hidden details (by using blood reagents not adequate on the original). Several cast formulations were tested for lifting the footwear impressions. The best results were achieved using Aroma fine®. Enhancement of the footwear impressions was attempted with several reagents prior to lifting, during the casting process, and on the lifted footwear impressions. Applying amido black to footwear impressions lifted with alginate produced the sharpest and most detailed footwear impressions. Alginate castings followed by chemical enhancement with amido black may produce high-quality footwear impressions for comparison. PMID:23488772

  16. RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol

    E-print Network

    Guo, John Zhanhu

    RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol: interfacial layer and bulk Abstract Iron oxide (a-phase) nanoparticles with coercivity larger than 300 Oe have been fabricated to effectively serve as a solid spacer to disperse the iron precursor and to prevent the nanoparticles from

  17. Structural-mechanical and thermophysical properties of modified polyvinyl chloride

    Microsoft Academic Search

    N. A. Bordyuk; Yu. N. Bestyuk; V. I. Nikitchuk; B. S. Kolupaev

    1991-01-01

    On the basis of a systematic investigation of the viscoelastic properties of polyvinyl chloride filled with waste from mineral fertilizer and phosphoric acid production in the form of highly dispersed phospho-gypsum, the specific heat is calculated and the energy of interaction of the structural elements of the system matrix is determined, together with the effective thermal conductivity coefficient, with allowance

  18. Interaction of collagen and poly(vinyl pyrrolidone) in blends

    Microsoft Academic Search

    Alina Sionkowska

    2003-01-01

    The interaction between collagen and poly(vinyl pyrrolidone) (PVP) in blends has been studied by viscometry, differential scanning calorimetry (DSC) and by Fourier transform infrared spectroscopy (FTIR). It was found that the amide A and amide I bands position in FTIR spectra of collagen were shifted after blending with PVP to higher wavenumbers. DSC measurements showed different melting temperature, glass transition

  19. Effect of natural gas odorants on polyvinyl chloride pipe

    Microsoft Academic Search

    A. R. Knight; A. Verma

    1975-01-01

    From studies of the effect of natural gas odorants on polyvinyl chloride and polyethylene pipe, the University of Saskatchewan and the Saskatchewan Power Corp. conclude that PE pipe is not affected by the odorants, while the mechanical strength of PVC pipe is affected by some. After 10-day exposures to liquid mercaptan-based odorants, the PE samples showed no physical changes and

  20. Poly-Sugar: Modification of Poly(vinyl Alcohol)

    Microsoft Academic Search

    A. M. Usmani; I. O. Salyer

    1979-01-01

    This paper describes the attachment of sugar (sucrose) onto low molecular weight poly(vinyl alcohols) (etherification) to produce a new class of synthetic sweetener. Because of its regulated molecular weight, the new sweetener would pass through the digestive tract and be excreted in its original molecular form. We have termed the new class of sweeteners poly-sugar. The etherification of sucrose with

  1. Enhancing the authenticity of assessments through grounding in first impressions.

    PubMed

    Hum?, Bogdana

    2014-10-27

    This article examines first impressions through a discursive and interactional lens. Until now, social psychologists have studied first impressions in laboratory conditions, in isolation from their natural environment, thus overseeing their discursive roles as devices for managing situated interactional concerns. I examine fragments of text and talk in which individuals spontaneously invoke first impressions of other persons as part of assessment activities in settings where the authenticity of speakers' stances might be threatened: (1) in activities with inbuilt evaluative components and (2) in sequential contexts where recipients have been withholding affiliation to speakers' actions. I discuss the relationship between authenticity, as a type of credibility issue related to intersubjective trouble, and the characteristics of first impression assessments, which render them useful for dealing with this specific credibility concern. I identify four features of first impression assessments which make them effective in enhancing authenticity: witness positioning (Potter, 1996, Representing reality: Discourse, rhetoric and social construction, Sage, London), (dis)location in time and space, automaticity, and extreme formulations (Edwards, 2003, Analyzing race talk: Multidisciplinary perspectives on the research interview, Cambridge University Press, New York). PMID:25346466

  2. Outcome dependency alters the neural substrates of impression formation

    PubMed Central

    Ames, Daniel L.; Fiske, Susan T.

    2015-01-01

    How do people maintain consistent impressions of other people when other people are often inconsistent? The present research addresses this question by combining recent neuroscientific insights with ecologically meaningful behavioral methods. Participants formed impressions of real people whom they met in a personally involving situation. fMRI and supporting behavioral data revealed that outcome dependency (i.e., depending on another person for a desired outcome) alters previously identified neural dynamics of impression formation. Consistent with past research, a functional localizer identified a region of dorsomedial PFC previously linked to social impression formation. In the main task, this ROI revealed the predicted patterns of activity across outcome dependency conditions: greater BOLD response when information confirmed (vs. violated) social expectations if participants were outcome-independent and the reverse pattern if participants were outcome-dependent. We suggest that, although social perceivers often discount expectancy-disconfirming information as noise, being dependent on another person for a desired outcome focuses impression-formation processing on the most diagnostic information, rather than on the most tractable information. PMID:23850465

  3. Solid oxide fuel cell anode degradation by the effect of siloxanes

    NASA Astrophysics Data System (ADS)

    Madi, Hossein; Lanzini, Andrea; Diethelm, Stefan; Papurello, Davide; Van herle, Jan; Lualdi, Matteo; Gutzon Larsen, Jørgen; Santarelli, Massimo

    2015-04-01

    Lifetime and durability issues connected with Solid Oxide Fuel Cell (SOFC) technology are strongly related to the amount of contaminants that reach the stack. In this study the focus is on organic silicon compounds (siloxanes) and their highly detrimental effects on the performance of SOFC Ni-YSZ anodes. The involved mechanism of degradation is clarified and quantified through several test runs and subsequent post-mortem analysis on tested samples. In particular, experiments on both Ni anode-supported single cells and 11-cell- stacks are performed, co-feeding D4-siloxane (octamethylcyclotetrasiloxane, C8H24O4Si4) as model compound for the organic silicon species which are generally found in sewage biogas. High degradation rates are observed already at ppb(v) level of contaminant in the fuel stream. Post-test analysis revealed that Si (as silica) is mostly deposited at the inlet of the fuel channel on both the interconnect and the anode side of the cell suggesting a relatively fast condensation-type process. Deposition of the Si was found on the interconnect and on the anode contact layer, throughout the anode support and the three phase boundary in the anode, correlating with the observed increase of polarization losses from the EIS analysis of tested cells.

  4. Study of zwitterionic sulfopropylbetaine containing reactive siloxanes for application in antibacterial materials.

    PubMed

    Chen, Shiguo; Chen, Shaojun; Jiang, Song; Mo, Yangmiao; Luo, Junxuan; Tang, Jiaoning; Ge, Zaochuan

    2011-07-01

    Antibacterial agents receive a great deal of attention around the world due to the interesting academic problems of how to combat bacteria and of the beneficial health, social and economic effects of successful agents. Scientists are actively developing new antibacterial agents for biomaterial applications. This paper reports the novel antibacterial agent siloxane sulfopropylbetaine (SSPB), which contains reactive alkoxysilane groups. The structure and properties of SSPB were systematically investigated, with the results showing that SSPB contains both quaternary ammonium compounds and reactive siloxane groups. SSPB has good antibacterial activity against both Escherichia coli (E. coli, 8099) and Staphylococcus aureus (S. aureus, ATCC 6538). The minimal inhibition concentration is 70 ?mol/ml SSPB against both E. coli and S. aureus. In addition, the SSPB antibacterial agent can be used in both weak acid and weak alkaline environments, functioning within the wide pH range of 4.0-9.0. The SSPB-modified glass surface killed 99.96% of both S. aureus and E. coli organisms within 24 h. No significant decrease was observed in this antibacterial activity after 20 washes. Moreover, SSPB does not induce a skin reaction and is nontoxic to animals. Thus, SSPB is an ideal candidate for future applications as a safe, environmentally friendly antibacterial agent. PMID:21450443

  5. Synthesis and Characterization of Thiol-Ene Functionalized Siloxanes and Evaluation of their Crosslinked Network Properties

    PubMed Central

    Cole, Megan A.; Bowman, Christopher N.

    2012-01-01

    Three types of linear thiol-functionalized siloxane oligomers and three types of ene-functionalized oligomers were synthesized and subsequently photopolymerized. Within each type of thiol-functionalized oligomer, the ratio of mercaptan repeat units to non-reactive phenyl repeat units was varied to manipulate both the crosslink density and the degree of secondary interactions through pi-pi stacking. Similarly, the repeat units of the three ene-functionalized oligomers are composed of allyl-functional monomers, benzene-functional monomers, and octyl-functional monomers in varying ratios of benzene:octyl but with a constant fraction of allyl moieties. The structural composition of the siloxane oligomers plays a pivotal role in the observed material properties of networks formed through thiol-ene photopolymerization. Networks with a high concentration of thiol functionalities exhibit higher rubbery moduli, ultimate strengths, and Young’s moduli than networks with lower thiol concentrations. Moreover, the concentration of functionalities capable of participating in secondary interactions via hydrogen bonding or pi-pi stacking directly impacts the network glass transition temperature and elasticity. The combination of low crosslink density and high secondary interactions produces networks with the greatest toughness. Finally, the fraction of octyl repeats correlates with the hydrophobic nature of the network. PMID:23162209

  6. Solvent effects on silica domain growth in silica/siloxane composite materials

    SciTech Connect

    Ulibarri, T.A.; Bates, S.E.; Black, E.P.; Schaefer, D.W. [Sandia National Labs., Albuquerque, NM (United States); Beaucage, W.G. [Univ. of Cincinnati, Cincinnati, OH (United States); Lee, M.K.; Moore, P.A.; Burns, G.T. [Dow Corning Corp., Midland, MI (United States)

    1995-07-01

    The effect of solvent addition on the phase separation, mechanical Properties and thermal stability of silica/siloxane composite materials prepared by in situ reinforcement was examined. The addition of a solvent enhances the miscibility of the reinforcement precursor, a partial hydrolyzate of tetraethoxysilane (TEOS-PH), with the polydimethylsiloxane (PDMS) polymer. As a result, the phase separation at the micron level, termed the large-scale structure, diminished in size. This decrease in particle size resulting from the addition of moderate amounts of solvent was accompanied by an improvement in the mechanical properties. However, solvent addition in the excess of 50 weight percent led to a decrease in mechanical properties even though the large-scale structure continued to diminish in size. Small Angle X-Ray Scattering (SAXS) was used to examine the Angstrom level or small-scale structure. This small-scale structure was only affected by the presence of solvent, not the amount. The silica/siloxane composite materials showed the same thermal transition temperatures as the original PDMS material.

  7. Potassium spin polarization lifetime for a 30-carbon chain siloxane film

    NASA Astrophysics Data System (ADS)

    Hibberd, Amber M.; Bergman, Susanna L.; Zhong, Yu Lin; Bernasek, Steven L.

    2012-11-01

    The siloxane film derived from the 30-carbon chain triacontyltrichlorosilane (TCTS) is studied as an anti-relaxation coating for atomic vapor cells. The longitudinal spin relaxation lifetime of optically pumped potassium atoms in the presence of TCTS is measured and the average number of non-relaxing atom-wall collisions, or bounces, enabled by the coated surface is determined. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) of TCTS were performed to investigate changes in chemical states and surface morphology of TCTS arising from K atom deposition on the film surface. TCTS was found to give approximately 530 bounces. Following lifetime measurements, K2p signals were clearly observed in XPS spectra. AFM images display non-preferential K deposition on the TCTS surface, however additional AFM studies with a TCTS surface exposed to Rb atoms show deposition occurs along surface defects. In agreement, Rb is found to preferentially deposit along the step edges of an 18-carbon chain monolayer film derived from 1-Octadecene. Finally, AFM indicates a much smoother surface for a tetracontane coating relative to TCTS. The importance of siloxane surface morphology versus film thickness with respect to coating performance is discussed.

  8. Impression Management Versus Intrapsychic Explanations in Social Psychology: A Useful Dichotomy?

    Microsoft Academic Search

    Philip E. Tetlock; Antony S. Manstead

    1985-01-01

    Impression management refers to the behavioral strategies that people use to create desired social images or identities. This article focuses on the current status of impression management explanations in social psychology. We argue that the common practice of referring to impression management theory is misleading. Many potential theories of impression management exist, each based on distinct assumptions. We also review

  9. Evaluation of acrylic polymeric resin and small siloxane molecule for protecting cultural heritage monuments against sulfur dioxide corrosion

    Microsoft Academic Search

    John Kapolos; Nicholas Bakaoukas; Athanasia Koliadima; George Karaiskakis

    2007-01-01

    The experimental technique of reversed-flow version of inverse gas chromatography was applied in order to evaluate the ability of an acrylic copolymer, Paraloid B-72 and a small siloxane molecule, Silo 111 to protect cultural heritage monuments against corrosion caused by the SO2 dry deposition. Because these materials act as surface modifiers the calculation of the time distribution of various physicochemical

  10. Effect of Time on Gypsum-Impression Material Compatibility

    NASA Astrophysics Data System (ADS)

    Won, John Boram

    The purpose of this study was to evaluate the compatibility of dental gypsum with three recently introduced irreversible hydrocolloid (alginate) alternatives. The test materials were Alginot® (Kerr™), Position Penta Quick® (3M ESPE™) and Silgimix ® (Sultan Dental™). The irreversible hydrocolloid impression material, Jeltrate Plus antimicrobial® (Dentsply Caulk™) served as the control. Materials and Methods: Testing of materials was conducted in accordance with ANSI/ADA Specification No. 18 for Alginate Impression Materials. Statistical Analysis: The 3-Way ANOVA test was used to analyze measurements between different time points at a significance level of (p < 0.05). Outcome: It was found that there was greater compatibility between gypsum and the alternative materials over time than the traditional irreversible hydrocolloid material that was tested. A statistically significant amount of surface change/incompatibility was found over time with the combination of the dental gypsum products and the control impression material (Jeltrate Plus antimicrobial®).

  11. Forming impressions: effects of facial expression and gender stereotypes.

    PubMed

    Hack, Tay

    2014-04-01

    The present study of 138 participants explored how facial expressions and gender stereotypes influence impressions. It was predicted that images of smiling women would be evaluated more favorably on traits reflecting warmth, and that images of non-smiling men would be evaluated more favorably on traits reflecting competence. As predicted, smiling female faces were rated as more warm; however, contrary to prediction, perceived competence of male faces was not affected by facial expression. Participants' female stereotype endorsement was a significant predictor for evaluations of female faces; those who ascribed more strongly to traditional female stereotypes reported the most positive impressions of female faces displaying a smiling expression. However, a similar effect was not found for images of men; endorsement of traditional male stereotypes did not predict participants' impressions of male faces. PMID:24897907

  12. Dynamic molecular resolution imaging of preocular fluid impressions

    PubMed Central

    Berry, M; Brayshaw, D; McMaster, T J

    2004-01-01

    Aim: The preocular fluid is renewed with molecules secreted by the underlying cells and with lacrimal gland secretions, while maintaining a stable surface topography. The authors tested the hypothesis that interactions between gelled and newly inserted mucins are the key to this stability. Methods: Using atomic force microscopy, the authors studied the topography of the freshly isolated preocular fluid obtained by impression cytology. The effects of adding mucins to this impression were compared with adding mucins to a pure mucin macromolecular assembly as a single component control to the more complex preocular fluid. The control structure was built up by repeated addition of pure ocular mucin to a tethering surface. Results: Imaging at molecular resolution showed a thin layer of superficial preocular fluid with an appearance consistent with a gel that was very flat, with surface roughness of approximately 0.1 nm. Mucin molecules adhering to a clean flat surface maintained their individual character when overlapping, whereas molecules integrating in the impression could not be followed individually. Both the preocular impression and the pure mucin assembly were stable under imaging for at least 90 minutes. The roughness of the pure mucin network decreased as more mucin was added. In contrast, there was a small increase in the roughness of the 2.25 ?m2 area of impression over the 60 minutes of continuous imaging, although locally there appeared to be infill of low height features. Disulphide bond breaking resulted in the collapse of the imaged structure in both the pure mucin control and the more complex ex vivo preocular impression. Conclusions: Polymeric mucins linked by disulphide bonds prevent or lessen loss of ocular surface material into the surrounding aqueous tears. PMID:15489494

  13. The fit of crowns produced using digital impression systems.

    PubMed

    Vennerstrom, Micael; Fakhary, Mobin; Von Steyern, Per Vult

    2014-01-01

    Compare the marginal and internal fit of crowns manufactured using four different digital impression systems with crowns manufactured using conventional impression technique, that served as a control group. Fifty all-ceramic crowns were fabricated using 50 standardized dies divided into five groups, each group representing one impression system. Each crown was cemented onto its respective model and sectioned into four segments.The marginal and internal fit were measured at 8 predefined points. A total of 1567 measurements were made, statistically analyzed and compared with crowns fabricated using the five systems. The following was found: (1) No significant difference was found with regard to mar ginal gap when comparing the control group to any of the digital systems. (2) Lava™ had smaller marginal gaps than CEREC® and iTero®, (3) CEREC and Lava had smaller gaps in the chamfer compared to iTero and the control, (4) E4D® showed smaller gaps than CEREC at measuring points 4-8 and CEREC a smaller gap at point 2, (5) Lava showed smaller gaps than CEREC at measuring points 1,3 and 5-8. (6) Lava had smaller gaps than iTero at measuring points 1-4,7 and 8. All differences presented were significant. In conclusions, crowns manufactured using digital impressions present a marginal and internal fit equal to, or better than, crowns made using a conventional impression method.The marginal and internal fit of reconstructions made using digital impression techniques could improve with a lower initial setting of the spacer. PMID:25796804

  14. Trophic transfer of methyl siloxanes in the marine food web from coastal area of Northern China.

    PubMed

    Jia, Hongliang; Zhang, Zifeng; Wang, Chaoqun; Hong, Wen-Jun; Sun, Yeqing; Li, Yi-Fan

    2015-03-01

    Methyl siloxanes, which belong to organic silicon compounds and have linear and cyclic structures, are of particular concern because of their potential characteristic of persistent, bioaccumulated, toxic, and ecological harm. This study investigated the trophic transfer of four cyclic methyl siloxanes (octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), and tetradecamethylcycloheptasiloxane (D7)) in a marine food web from coastal area of Northern China. Trophic magnification of D4, D5, D6, and D7 were assessed as the slope of lipid equivalent concentrations regressed against trophic levels of marine food web configurations. A significant positive correlation (R = 0.44, p < 0.0001) was found between lipid normalized D5 concentrations and trophic levels in organisms, showing the trophic magnification potential of this chemical in the marine food web. The trophic magnification factor (TMF) of D5 was estimated to be 1.77 (95% confidence interval (CI): 1.41-2.24, 99.8% probability of the observing TMF > 1). Such a significant link, however, was not found for D4 (R = 0.14 and p = 0.16), D6 (R = 0.01 and p = 0.92), and D7 (R = -0.15 and p = 0.12); and the estimated values of TMFs (95% CI, probability of the observing TMF > 1) were 1.16 (0.94-1.44, 94.7%), 1.01 (0.84-1.22, 66.9%) and 0.85 (0.69-1.04, 48.6%) for D4, D6, and D7, respectively. The TMF value for the legacy contaminant BDE-99 was also estimated as a benchmark, and a significant positive correlation (R = 0.65, p < 0.0001) was found between lipid normalized concentrations and trophic levels in organisms. The TMF value of BDE-99 was 3.27 (95% CI: 2.49-4.30, 99.7% probability of the observing TMF > 1), showing the strong magnification in marine food webs. To the best of our knowledge, this is the first report on the trophic magnification of methyl siloxanes in China, which provided important information for trophic transformation of these compounds in marine food webs. PMID:25625298

  15. Cross-linked polyvinyl alcohol and method of making same

    NASA Technical Reports Server (NTRS)

    Hsu, L. C.; Sheibley, D. W.; Philipp, W. H. (inventors)

    1981-01-01

    A film-forming polyvinyl alcohol polymer is mixed with a polyaldehyde-polysaccharide cross-linking agent having at least two monosaccharide units and a plurality of aldehyde groups per molecule, perferably an average of at least one aldehyde group per monosaccharide units. The cross-linking agent, such as a polydialdehyde starch, is used in an amount of about 2.5 to 20% of the theoretical amount required to cross-link all of the available hydroxyl groups of the polyvinyl alcohol polymer. Reaction between the polymer and cross-linking agent is effected in aqueous acidic solution to produce the cross-linked polymer. The polymer product has low electrical resistivity and other properties rendering it suitable for making separators for alkaline batteries.

  16. Surface acoustic wave humidity sensor using polyvinyl-alcohol film

    Microsoft Academic Search

    M. Penza; V. I. Anisimkin

    1999-01-01

    A surface acoustic wave (SAW) sensor has been fabricated and used to study the hygroscopic properties of the polyvinyl-alcohol (PVA) polymer film as layer chemically sensitive to relative humidity (RH). A 42 MHz SAW device has been configured as delay line onto 128° YX-LiNbO3 substrate with the SAW path totally covered by the spin-coated PVA film. The SAW phase response

  17. Electrical conductivity of polyvinyl alcohol-multiwall carbon nanotubes composites

    NASA Astrophysics Data System (ADS)

    Amrin, Sayed; Deshpande, V. D.

    2013-06-01

    The dc and ac conductivity of polyvinyl alcohol (PVA)-multiwalled carbon nanotube (MWNT) nanocomposites prepared by solution casting were investigated by employing dielectric relaxation spectroscopy in broad frequency range (0.1 Hz-10 MHz) at room temperature as a function of the conductive weight fraction (p) ranging from 0 to 2wt.%. The frequency dependence of the measured conductivity obeys the universal dynamic response (UDR); a dc plateau followed, by the power law above a critical frequency (fc).

  18. Preparation and characterization of bioglass\\/polyvinyl alcohol composite hydrogel

    Microsoft Academic Search

    Hong Xu; Yingjun Wang; Yudong Zheng; Xiaofeng Chen; Li Ren; Gang Wu; Xiaoshan Huang

    2007-01-01

    In order to form firm active fixation with the adjacent bone, a new kind of bioactive composite hydrogel was prepared with polyvinyl alcohol (PVA) and bioglass (BG) through ultrasonic dispersion, heat-high-pressure and freeze\\/thawed technique. A digital speckle correlation method (DSCM) was utilized to characterize the mechanical properties of the series of BG\\/PVA composites. Results showed that at different load pressures,

  19. Polyvinyl Alcohol Based Membrane as Separator for Alkaline Water Electrolyzer

    Microsoft Academic Search

    S. Seetharaman; S. Ravichandran; D. J. Davidson; S. Vasudevan; G. Sozhan

    2011-01-01

    Alkaline water Electrolyzer employs Nickel based electrodes and asbestos cloth diaphragm. Asbestos is considered as carcinogenic. In order to limit the usage of asbestos diaphragm, separator membrane was synthesized from polyvinyl alcohol, glutaraldehyde, N,N,N'N'-Tetramethyl hexane-1,6 diamine and Titanium dioxide. The role of N,N,N'N'-Tetramethyl hexane-1,6 diamine is to improve the dimensional stability of the membrane. The fabricated membranes were characterized by

  20. Radiation-induced degradation of polyvinyl alcohol in aqueous solutions

    Microsoft Academic Search

    Shu-Juan Zhang; Han-Qing Yu

    2004-01-01

    The degradation of polyvinyl alcohol (PVA) by ?-ray irradiation was investigated. Degradation efficiency of PVA was influenced by several factors, such as initial PVA concentration, dose rate, pH, and the addition of H2O2. The degradation kinetics depended on initial PVA concentration and dose rate. At a relatively lower PVA concentration, e.g., 180mg\\/L, and a higher dose rate, e.g., 55.7Gy\\/min, the

  1. Poly(vinyl alcohol) hydrogels as soft contact lens material

    Microsoft Academic Search

    Suong-Hyu Hyon; Won-Ill Cha; Yoshito Ikada; Mihori Kita; Yuichiro Ogura; Yoshihito Honda

    1994-01-01

    A new type of soft contact lens was developed from the poly(vinyl alchol) (PVA) hydrogel prepared by a low temperature crystallization technique using a water-dimethyl sulfoxide mixed solvent. The PVA contact lens materials had a water content of 78% and a tensile strength of 50 kg\\/cm, five times as strong as that of commercial poly(2-hydroxyethyl methacrylate) soft contact lens. The

  2. Structural-mechanical and thermophysical properties of modified polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Bordyuk, N. A.; Bestyuk, Yu. N.; Nikitchuk, V. I.; Kolupaev, B. S.

    1991-06-01

    On the basis of a systematic investigation of the viscoelastic properties of polyvinyl chloride filled with waste from mineral fertilizer and phosphoric acid production in the form of highly dispersed phospho-gypsum, the specific heat is calculated and the energy of interaction of the structural elements of the system matrix is determined, together with the effective thermal conductivity coefficient, with allowance for energy dissipation by the elements of the structure.

  3. Preparation and properties of microfibrillated cellulose polyvinyl alcohol composite materials

    Microsoft Academic Search

    Jue Lu; Tao Wang; Lawrence T. Drzal

    2008-01-01

    This work reports the preparation of MFC–PVA composite films, and the thermal and mechanical properties of these films. Microfibrillated cellulose (MFC), which was separated from kraft pulp by a mechanical process, was used as the reinforcement in polyvinyl alcohol (PVA) matrix. This MFC reinforcement has an interconnected web-like structure with fibrils having a diameter in the range of 10–100nm, as

  4. Emotional Regulation at Walt Disney World: An Impression Management View

    Microsoft Academic Search

    Anne Reyers; Jonathan Matusitz

    2012-01-01

    In this article, the authors conceptually analyze the emotional regulation strategies used by Walt Disney World onstage employees as a way to fulfill requirements set forth by the corporation. Emotional regulation refers to the regulation of employees' emotions to fulfill occupational or organizational standards. The authors' framework for emotional regulation is inspired by Goffman's (1959) impression management, a type of

  5. Modeling first impressions from highly variable facial images

    PubMed Central

    Vernon, Richard J. W.; Sutherland, Clare A. M.; Young, Andrew W.; Hartley, Tom

    2014-01-01

    First impressions of social traits, such as trustworthiness or dominance, are reliably perceived in faces, and despite their questionable validity they can have considerable real-world consequences. We sought to uncover the information driving such judgments, using an attribute-based approach. Attributes (physical facial features) were objectively measured from feature positions and colors in a database of highly variable “ambient” face photographs, and then used as input for a neural network to model factor dimensions (approachability, youthful-attractiveness, and dominance) thought to underlie social attributions. A linear model based on this approach was able to account for 58% of the variance in raters’ impressions of previously unseen faces, and factor-attribute correlations could be used to rank attributes by their importance to each factor. Reversing this process, neural networks were then used to predict facial attributes and corresponding image properties from specific combinations of factor scores. In this way, the factors driving social trait impressions could be visualized as a series of computer-generated cartoon face-like images, depicting how attributes change along each dimension. This study shows that despite enormous variation in ambient images of faces, a substantial proportion of the variance in first impressions can be accounted for through linear changes in objectively defined features. PMID:25071197

  6. Impressions of a Middle Grades STEM Integration Program

    ERIC Educational Resources Information Center

    Stohlmann, Micah; Moore, Tamara J.; McClelland, J.; Roehrig, Gillian H.

    2011-01-01

    This article describes the experiences of one Minnesota middle school that implemented a year-long integrated STEM program with the cooperation of graduate student fellows from a local university. The authors, two of whom were among the graduate students involved in the project, describe their impressions of the program, share some lessons they…

  7. Impressions of Counselors as a Function of Counselor Physical Attractiveness

    ERIC Educational Resources Information Center

    Carter, Jean A.

    1978-01-01

    Research assessed the effects of counselor physical attractiveness and inter-actions between attractiveness and counselor subject sex. It is suggested that sex of counselor and client may play a more important role independently and in conjunction with attractiveness than does attractiveness alone in influencing impressions and expectations.…

  8. Forming On-Line Impressions: A Class Exercise

    ERIC Educational Resources Information Center

    Bishop-Clark, Cathy; Dietz-Uhler, Beth

    2003-01-01

    In an exercise designed to assess the accuracy of the impressions we form of people in online settings, students in a Psychology of the Internet course were asked to interact with two people in two different Internet settings. First, students were asked to interact with "Tom" (a college student) in an asynchronous discussion board setting over the…

  9. Course Evaluations: Are Students' Ratings Dictated by First Impressions?

    ERIC Educational Resources Information Center

    Hewett, Laura; And Others

    The relationship between students' first impressions of a course (formed on the basis of their initial exam scores) and end-of-term teacher evaluation ratings was studied. University students enrolled in freshman, sophomore, and junior level courses took all tests and completed the instructor evaluation form the week before the fourth quarterly…

  10. Handwriting and Students with Disabilities: Overcoming First Impressions.

    ERIC Educational Resources Information Center

    Greenland, Roy; Polloway, Edward A.

    Students with disabilities often experience particular difficulties with handwriting, and these problems can hinder their development both in school and in postsecondary settings. This paper addresses three issues: (1) the possibility of a prejudicial and potentially lasting first impression, based on the individual's handwriting; (2) the lack of…

  11. Cross-Cultural Impression Management: A Cultural Knowledge Audit Model

    ERIC Educational Resources Information Center

    Spong, Abigail; Kamau, Caroline

    2012-01-01

    Purpose: Many people moving into a new culture for work or study do so without prior cross-cultural training, yet successful cultural adaptation has important ramifications. The purpose of this paper is to focus on cross-cultural impression management as an element of cultural adaptation. Does cultural adaptation begin by paying strong attention…

  12. Seeing Writing Instruction Differently: Lessons with Lasting Impressions

    ERIC Educational Resources Information Center

    Bintz, William P.; Dillard, Jill

    2004-01-01

    A case of Jill, an elementary school teacher who takes a reflection practitioner stance on her teaching is described. Three different social practices used by Jill to help her struggling third-grade students learn to write and some of the lasting impressions based on the whole experience are highlighted.

  13. Social Behavioral Assessment and Intervention: Observations and Impressions

    ERIC Educational Resources Information Center

    Gresham, Frank M.

    2011-01-01

    The author was favorably impressed with the breadth, scope, and quality of the articles in this issue that dealt with the various aspects and correlates of social behavioral functioning as well as assessment and intervention considerations. Each of these articles dealt with a unique aspect of social behavioral functioning in children and youth and…

  14. Impression Formation and Modifiability: Testing a Theoretical Model

    ERIC Educational Resources Information Center

    Mrug, Sylvie; Hoza, Betsy

    2007-01-01

    This study proposed and tested a developmental model of impression formation based on observed behavior, prior expectancies, and additional incongruent information. Participants were 51 kindergartners, 53 second graders, and 104 college students who provided trait and liking judgments after watching a child actor engage in behaviors from three…

  15. POVERTY REDUCTION IN VIET NAM: DISHARMONIES BEHIND THE IMPRESSIVE ACHIEVEMENTS

    Microsoft Academic Search

    Nguyen Thang; Vu Hoang Dat; Viet Nam

    The economy of Viet Nam is considered in two versions. First, in the simple presentation, the households are all pooled together and only monetary values are considered. In such a presentation, Viet Nam's economic growth and the progress in poverty reduction since 1993 is really impressive. After twelve years, poverty incidence cut down by nearly two thirds, while the inequality,

  16. The Neurological-Impress Method of Teaching Reading.

    ERIC Educational Resources Information Center

    Partridge, Susan

    In the neurological impress method the teacher sits slightly behind the child, a book is held jointly, and the teacher and child read aloud simultaneously with the teacher directing his/her voice into the child's ear as the child slides a finger along each line following the words as they are spoken. No attempt is made to teach sounds or word…

  17. DETAIL OF THE IMPRESSION IN THE CONCRETE SLAB OF THE ...

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

    DETAIL OF THE IMPRESSION IN THE CONCRETE SLAB OF THE SOUTH END OF THE ABOVE-GROUND PORTION. NOTE STEP DOWN TO THE STEEL PLATE IN BACKGROUND. VIEW FACING NORTH - U.S. Naval Base, Pearl Harbor, Ford Island 5-Inch Antiaircraft Battery, Battery Command Center, Ford Island, Pearl City, Honolulu County, HI

  18. Method for creating stomatal impressions directly onto archivable microscope slides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stomatal density has been shown to be a primary determinant of water use efficiency, limitation to CO2 assimilation rate and yield. Widely used methods of stomatal impressioning sample small regions of the leaf, are labor intensive, or do not yield stable archivable samples for potentially revisitin...

  19. Thermal neutron detection by entrapping 6LiF nanocrystals in siloxane scintillators

    NASA Astrophysics Data System (ADS)

    Carturan, S. M.; Marchi, T.; Maggioni, G.; Gramegna, F.; Degerlier, M.; Cinausero, M.; Dalla Palma, M.; Quaranta, A.

    2015-06-01

    Exploiting the long experience in design and production of scintillating mixtures based on siloxane matrices with combinations of primary dye and waveshifter, a first set of 6LiF loaded scintillator disks has been produced. The synthesis is herein described and reported, as well as preliminary results on their light response towards thermal neutrons. The preservation of transparency and mechanical integrity of the scintillator material is challenging when introducing the inorganic salt LiF which is a "foreign body" to the organic polysiloxane host matrix Different strategies such as synthesis of nanoparticles and surface functionalization have been pursued to succeed in the entrapment of the neutron converter whilst maintaining moderate light output, optical transparency and flexibility of the base scintillator.

  20. Gas permeability of cross-linked poly(ethylene-oxide) based on poly(ethylene glycol) dimethacrylate and a miscible siloxane co-monomer

    Microsoft Academic Search

    Victor A. Kusuma; Gabriella Gunawan; Zachary P. Smith; Benny D. Freeman

    2010-01-01

    Pure gas permeability coefficients of a series of copolymers based on polar, hydrophilic poly(ethylene glycol) dimethacrylate, n = 14 (PEGDMA) and siloxane-based co-monomer, [methyl bis(trimethylsiloxy)silyl] propyl glycerol methacrylate (SiGMA) are reported. SiGMA is miscible with PEGDMA and able to form homogeneous films. SiGMA contains a bulky siloxane-based end group, which acts to increase permeability, and an –OH pendant group, which increases miscibility

  1. Synthesis of ethers by GaBr3 -catalyzed reduction of carboxylic acid esters and lactones by siloxanes.

    PubMed

    Biermann, Ursula; Metzger, Jürgen O

    2014-02-01

    Ethers were synthesized by reduction of the respective esters catalyzed by gallium bromide (GaBr3 ) and using siloxanes, preferentially 1,1,3,3-tetramethyldisiloxane, as reductant. Methyl oleate, triglycerides, that is, tributyrine and glyceryl triundec-10-enoate as well as ?- and ?-lactones were converted into the respective ethers in high to moderate yields. ?-Lactones were reduced with high selectivity in the presence of a methyl ester functionality. The reduction has been carried out at room temperature or moderately elevated temperature of up to 60 °C using stoichiometric amounts of the reductant and 0.005-0.01 equiv of GaBr3 as catalyst per ester functionality without any solvent added. After a reaction time of 1-4 h the conversion of the substrate was 100 %. The product was separated from polymeric siloxanes formed as coupled product by simple distillation. PMID:24488681

  2. Flowing of light-bodied elastic impression materials.

    PubMed

    Hegdahl, T; Gjerdet, N R

    1981-01-01

    The ability of light-bodied elastomeric and reversible hydrocolloid impression materials to spread on a surface was studied in vitro. The material which most readily coated the surface was a polysulfide, followed by silicone, hydrocolloid, and polyether materials. The influence of surface energy was studied by comparing the spreading of impression materials on high energy (glass) and low energy (PTFE) surfaces. Only for polysulfide and hydrocolloid materials was any effect observed: The glass was more readily coated than PTFE. As a result of an increase in temperature of the elastomeric materials a reduction in the materials' ability to wet the surface was found for silicones and polysulfide, but not for polyether. An addition-polymerized silicone product showed the strongest temperature dependence. A strong negative correlation was found between spreading ability and viscosity of elastomeric materials. PMID:6943907

  3. Finite Element Analysis of Plastic Deformation During Impression Creep

    NASA Astrophysics Data System (ADS)

    Naveena; Ganesh Kumar, J.; Mathew, M. D.

    2015-04-01

    Finite element (FE) analysis of plastic deformation associated with impression creep deformation of 316LN stainless steel was carried out. An axisymmetric FE model of 10 × 10 × 10 mm specimen with 1-mm-diameter rigid cylindrical flat punch was developed. FE simulation of impression creep deformation was performed by assuming elastic-plastic-power-law creep deformation behavior. Evolution of the stress with time under the punch during elastic, plastic, and creep processes was analyzed. The onset of plastic deformation was found to occur at a nominal stress about 1.12 times the yield stress of the material. The size of the developed plastic zone was predicted to be about three times the radius of the punch. The material flow behavior and the pile-up on specimen surface have been modeled.

  4. e-Perceptions: Personality Impressions Based on Personal Websites

    Microsoft Academic Search

    Simine Vazire; Samuel D. Gosling

    2004-01-01

    This research examined the accuracy of personality impressions based on personal websites, a rapidly growing medium for self-expression, where identity claims are predominant. Eighty-nine websites were viewed by 11 observers, who rated the website authors' personalities. The ratings were compared with an accuracy criterion (self- and informant reports) and with the authors' ideal-self ratings. The websites elicited high levels of

  5. Effect of segmented poly(ester-siloxane)urethanes compositional parameters on differential scanning calorimetry and dynamic-mechanical measurements

    Microsoft Academic Search

    S Ioan; G Grigorescu; A Stanciu

    2002-01-01

    Segmented poly(ester-siloxane)urethanes containing hard and soft segments were prepared by melt polyaddition using a multistep procedure. The soft segments based on poly(ethylene glycol adipate)diol as ester sequences and ?,?-poly(dimethylsiloxane)diol as silicone sequences were synthesized. The hard segments were based on aromatic or aliphatic diisocyanates and butanediol was used as chain extender. These polyurethane materials were analysed by differential scanning calorimetry

  6. Surface Modification of Sylgard-184 Poly(dimethyl siloxane) Networks by Ultraviolet and Ultraviolet\\/Ozone Treatment

    Microsoft Academic Search

    Kirill Efimenko; William E. Wallace; Jan Genzer

    2002-01-01

    We report on the surface modification of Sylgard-184 poly(dimethyl siloxane) (PDMS) networks by ultraviolet (UV) radiation and ultraviolet\\/ozone (UVO) treatment. The effects of the UV light wavelength and ambient conditions on the surface properties of Sylgard-184 are probed using a battery of experimental probes, including static contact angle measurements, Fourier transform infrared spectroscopy, near-edge X-ray absorption fine structure, and X-ray

  7. Implantation of a new porous gelatin–siloxane hybrid into a brain lesion as a potential scaffold for tissue regeneration

    Microsoft Academic Search

    Kentaro Deguchi; Kanji Tsuru; Takeshi Hayashi; Mikiro Takaishi; Mitsuyuki Nagahara; Shoko Nagotani; Yoshihide Sehara; Guang Jin; HanZhe Zhang; Satoshi Hayakawa; Mikio Shoji; Masahiro Miyazaki; Akiyoshi Osaka; Nam-Ho Huh; Koji Abe

    2006-01-01

    For brain tissue regeneration, any scaffold for migrated or transplanted stem cells with supportive angiogenesis is important once necrotic brain tissue has formed a cavity after injury such as cerebral ischemia. In this study, a new porous gelatin–siloxane hybrid derived from the integration of gelatin and 3-(glycidoxypropyl) trimethoxysilane was implanted as a three-dimensional scaffold into a defect of the cerebral

  8. Enhanced pervaporation performance of poly (dimethyl siloxane) membrane by incorporating titania microspheres with high silver ion loading

    Microsoft Academic Search

    Wanpeng Liu; Ben Li; Ruijian Cao; Zhongyi Jiang; Shengnan Yu; Guanhua Liu; Hong Wu

    2011-01-01

    Facilitated transport membranes were fabricated by incorporating Ag+ loaded titania (TiO2) microspheres into poly (dimethyl siloxane) (PDMS) matrix for pervaporative desulfurization of model gasoline. The pristine monodispersed TiO2 microspheres with controllable particle size were synthesized via a modified sol–gel method. The surface of TiO2 microspheres was then coated with dopamine through bioadhesion-inspired strategy. Subsequently, the Ag+ ions were coordinated with

  9. Selling Oneself: Construct and Criterion-Related Validity of Impression Management in Structured Interviews

    Microsoft Academic Search

    Martin Kleinmann; Ute-Christine Klehe

    2010-01-01

    Interviewee impression management has been a long-standing concern in the interview literature. Yet recent insights into the impact of impression management on interviewee performance in structured interviews suggest that interviewee impression management may be more than just a source of bias and a nuisance. Rather, impression management should possess construct-related validity and contribute to the interviews' criterion-related validity. These hypotheses

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

    SciTech Connect

    Schweigkofler, M.; Niessner, R.

    1999-10-15

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

  11. Solid State NMR Measurements for Preliminary Lifetime Assessments in gamma-Irradiated and Thermally Aged Siloxane Elastomers

    SciTech Connect

    Chinn, S C; Herberg, J L; Sawvel, A M; Maxwell, R S

    2004-11-29

    Siloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. NMR parameters such as transverse ( T{sub 2}) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and MRI results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

  12. Solid State NMR Measurements for Preliminary Lifetime Assessments in (gamma)-Irradiated and Thermally Aged Siloxane Elastomers

    SciTech Connect

    Chinn, S C; Herberg, J L; Sawvel, A M; Maxwell, R S

    2005-02-03

    Siloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with changes in composition and filler content. They are, however, subject to degradation in radiatively and thermally harsh environments. We are using solid state nuclear magnetic resonance techniques to investigate changes in network and interfacial structure in siloxane elastomers and their correlations to changes in engineering performance in a series of degraded materials. Nuclear magnetic resonance (NMR) parameters such as transverse (T{sub 2}) relaxation times, cross relaxation rates, and residual dipolar coupling constants provide excellent probes of changes crosslink density and motional dynamics of the polymers caused by multi-mechanism degradation. The results of NMR studies on aged siloxanes are being used in conjunction with other mechanical tests to provide insight into component failure and degradation kinetics necessary for preliminary lifetime assessments of these materials as well as into the structure-property relationships of the polymers. NMR and magnetic resonance imaging (MRI) results obtained both from high resolution NMR spectrometers as well as low resolution benchtop NMR screening tools will be presented.

  13. Computer-Mediated Impression Formation: A Test of the Sticky Cues Model Using Facebook

    ERIC Educational Resources Information Center

    Van Der Heide, Brandon Lee

    2009-01-01

    This research offers a model of online impression formation that explains how different impression-bearing cues may carry more or less informational value. This research considers the possibility that impression-bearing cues have greater informational value when those cues are distinctive and are task-relevant. This research refers to such cues as…

  14. Crowns and other extra-coronal restorations: Impression materials and technique

    Microsoft Academic Search

    D Barker; A W G Walls; R W Wassell

    2002-01-01

    Well-fitting indirect restorations can only be made if there are accurate models of the oral tissues available, made from high quality impressions. Waiting for an impression to set may be more stressful for the dentist than the patient. Should the impression need to be repeated there is the embarrassment of having to explain this to the patient, the cost implications

  15. EFFECT OF IMPRESSION MATERIAL, TRAY SPACE AND ATTACHMENT ON CAST ACCURACY

    Microsoft Academic Search

    Ayodeji Idowu; H. Mohammed-AI Tahawi; Yousef F. Talk; Bassem F. ElMallakM BDS

    At King Saud University's College of Dentistry, final impressions for removable partial dentures are made using polysulfide rubber, fast-set and regular set irreversible hydrocolloid impression materials. Custom trays used are either single-spaced or double spaced. Further, impression material attachment to the tray could be through tray perforations or the use of adhesives. Literature to support each one of these methods

  16. Polyvinyl alcohol doped with nickel chloride hexahydrate as conductor polymer

    NASA Astrophysics Data System (ADS)

    Ruiz-Limon, B.; Olivares-Perez, Arturo; Silva-Andrade, F.; Fuentes-Tapia, I.; Ibarra-Torres, Juan Carlos

    2004-06-01

    Polyvinyl alcohol is a viscous solution, with blue clear appearance, not has odor, when is deposited, as a film dry the appearance is clear transparent and has high flexibility. This polymer no has double link and don not has p orbital that permit the conductivity. However, can be doped with salts as ammonium dichromate and nickel chloride hexahydrate NiCl26H2O constructing a good conductor polymer with a resistivity around 300 ohms cm. Conserving the high flexibility opened new possibilities and applications.

  17. Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol

    SciTech Connect

    Tuncer, Enis [ORNL; Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL; Duckworth, Robert C [ORNL

    2008-01-01

    In the current study the focus is on dielectric properties (as a function of frequency and temperature) of a polymeric composite system composed of polyvinyl alcohol and barium titanate nano powder. In the investigations, the temperature range is between 50-295 K, and the frequency range is between $20\\ \\hertz-1\\ \\mega\\hertz$. Polarization and conduction processes are investigated in the linear regime. Dielectric breakdown strengths of samples are also reported. The materials presented have potential to be implemented in cryogenic capacitor or field grading applications.

  18. Memristive learning and memory functions in polyvinyl alcohol polymer memristors

    NASA Astrophysics Data System (ADS)

    Lei, Yan; Liu, Yi; Xia, Yidong; Gao, Xu; Xu, Bo; Wang, Suidong; Yin, Jiang; Liu, Zhiguo

    2014-07-01

    Polymer based memristive devices can offer simplicity in fabrication and at the same time promise functionalities for artificial neural applications. In this work, inherent learning and memory functions have been achieved in polymer memristive devices employing Polyvinyl Alcohol. The change in conduction in such polymer devices strongly depends on the pulse amplitude, duration and time interval. Through repetitive stimuli training, temporary short-term memory can transfer into consolidated long-term memory. These behaviors bear remarkable similarities to certain learning and memory functions of biological systems.

  19. Electrical and Thermal Properties of Polyvinyl Acetal Based Nanocomposites

    SciTech Connect

    Sauers, Isidor [ORNL; James, David Randy [ORNL; Ellis, Alvin R [ORNL; Tuncer, Enis [ORNL; Polyzos, Georgios [ORNL; Pace, Marshall O [ORNL

    2009-10-01

    A water chemistry procedure is used to synthesize titanium dioxide nanoparticles which can later be blended with a polymer to form a nanodielectric. The synthesized nanoparticles are dispersed in two grades of polyvinyl acetal (commercially available under the trade names BX-L and KS-10, manufactured by SEKISUI Chemicals). Nanocomposite materials were prepared with 15 and 33 wt% titanium dioxide. The variation of the glass transition temperature with increasing filler weight fraction is presented. The dielectric breakdown strengths of the nanodielectric samples are reported. The presented results can be employed to optimize the dielectric properties of the studied nanocomposites for potential use in cryogenic high voltage applications.

  20. RADIOCHEMICAL ALTERATIONS IN POLYVINYL CHLORIDE UNDER THE EFFECT OF Co⁶° GAMMA RADIATION

    Microsoft Academic Search

    Wuckel

    1960-01-01

    The role of air oxygen in the radiochemical changes of polyvinyl ; chloride was investigated. A polyvinyl chloride emulsion polymeride with a K ; value of 60 to 65 was used as a sample. It was radiated in the form of powder, ; films, and massive cylinders in high vacuum and in air. The total viscosity of ; the powders

  1. Controlling the color of Lippmann holograms recorded in dichromated gelatin polyvinyl alcohol

    Microsoft Academic Search

    Tiequan Cai; Yixing Tang; Hui Wang; Chaoming Dai; Lu-Rong Guo

    1993-01-01

    The polyvinyl alcohol and several other organic materials are mixed into the aqueous gelatin while the film is coated. This thin solid film is sensitized by aqueous ammonium dichromate, so it is called a dichromated gelatin polyvinyl alcohol (DC-GPVA) holographic recording material. DC-GPVA not only possesses the same excellent holographic properties as the conventional dichromated gelatin (DCG) but also obviously

  2. Preparation and Properties of Biodegradable Polymer Film Based on Polyvinyl Alcohol and Tropical Fruit Waste Flour

    Microsoft Academic Search

    Ooi Xian Zhong; Hanafi Ismail; Nor Aziah Abdul Aziz; Azhar Abu Bakar

    2011-01-01

    In this study, two different types of tropical fruit waste flour, rambutan waste flour (RWF) and banana waste flour (BWF), were blended with polyvinyl alcohol (PVOH) by solution casting method. The structure of the blend film was characterised by Fourier Transform Infrared Spectroscopy. The tensile strength and elongation at break of tropical fruit waste flour-filled polyvinyl alcohol were lower, but

  3. Rapidly dissolving poly(vinyl alcohol)/cyclodextrin electrospun nanofibrous membranes

    E-print Network

    Khan, Saad A.

    complexes of poly(vinyl alcohol) (PVA), hydroxypropyl-b-cyclodextrin (HPbCD), and a poorly water soluble of these complexes within electrospun polymer nanobers is yet to be fully explored. Cyclodextrins have beenRapidly dissolving poly(vinyl alcohol)/cyclodextrin electrospun nanofibrous membranes Joshua L

  4. Remembering first impressions: Effects of intentionality and diagnosticity on subsequent memory

    PubMed Central

    Gilron, Roee; Gutchess, Angela H.

    2012-01-01

    People rely on first impressions every day as an important tool to interpret social behavior. While research is beginning to reveal the neural underpinnings of first impressions, particularly through understanding the role of dorsal medial prefrontal cortex (dmPFC), little is known about the way in which first impressions are encoded into memory. This is surprising because first impressions are relevant from a social perspective for future interactions, requiring that they be transferred to memory. The present study used a subsequent memory paradigm to test the conditions under which the dmPFC is implicated in the encoding of first impressions. We found that intentionally forming impressions engages the dmPFC more than incidentally forming impressions and that this engagement supports the encoding of remembered impressions. In addition, we found that diagnostic information, which more readily lends itself to forming trait impressions, engages the dmPFC more than neutral information. These results indicate that the neural system subserving memory for impressions is sensitive to consciously formed impressions. The results also suggest a distinction between a social memory system and other explicit memory systems governed by the medial temporal lobes. PMID:22139633

  5. Damage Mechanisms of Filled Siloxanes for Predictive Multiscale Modeling of Aging Behavior

    SciTech Connect

    Balazs, B; Maxwell, R; de Teresa, S; Dinh, L; Gee, R

    2002-04-02

    Predictions of component performance versus lifetime are often risky for complex materials in which there may be many underlying aging or degradation mechanisms. In order to develop more accurate predictive models for silica-filled siloxane components, we are studying damage mechanisms over a broad range of size domains, linked together through several modeling efforts. Atomistic and molecular dynamic modeling has elucidated the chemistry of the silica filler to polymer interaction, as this interaction plays a key role in this material's aging behavior. This modeling work has been supported by experimental data on the removal of water from the silica surface, the effect of the surrounding polymer on this desiccation, and on the subsequent change in the mechanical properties of the system. Solid State NMR efforts have characterized the evolution of the polymer and filler dynamics as the material is damaged through irradiation or desiccation. These damage signatures have been confirmed by direct measurements of changes in polymer crosslink density and filler interaction as measured by solvent swelling, and by mechanical property tests. Data from the changes at these molecular levels are simultaneously feeding the development of age-aware constitutive models for polymer behavior. In addition, the microstructure of the foam, including under load, has been determined by Computed Tomography, and this data is being introduced into Finite Element Analysis codes to allow component level models. All of these techniques are directed towards the incorporation of molecular and microstructural aging signatures into predictive models for overall component performance.

  6. Biological removal of siloxanes from landfill and digester gases: opportunities and challenges.

    PubMed

    Popat, Sudeep C; Deshusses, Marc A

    2008-11-15

    The presence of volatile methyl siloxanes (VMSs) presents challenges for using landfill and digester gases as energy fuels because of the formation of silicon dioxide deposits during combustion. This study looks at the feasibility of using biological treatment to control VMSs. Biotrickling filters removing octamethylcyclotetrasiloxane (D4), selected as a model VMS, from aerobic and anaerobic waste gas streams were setup. The efficacy of both aerobic and anaerobic biotrickling filters was low. The removal of D4 in the aerobic biotrickling filter followed a linear trend, reaching 43% at a gas empty bed residence time of 19.5 min. Aerobic biodegradation of D4 in shake flasks was found to be extremely slow, with trace concentrations requiring 3-4 months for complete degradation. Gas-liquid partition tests revealed that D4 partitions poorly into aqueous phases and that interphase mass transfer is slow. Using the mass transfer data, we estimated the maximum possible mass transfer rate of D4 in the biotrickling filter to be in the range of 30-100 mg m(-3) h(-1). These values are low and suggest that mass transfer limitations play an important role in the low treatment performance that was observed. The possibility of enhancing D4 mass transfer by using oleyl alcohol as a second nonmiscible liquid phase was unsuccessful. Overall, the results demonstrate that biological treatment of D4 vapors is possible but poses significant challenges. PMID:19068840

  7. AFM in peak force mode applied to worn siloxane-hydrogel contact lenses.

    PubMed

    Abadías, Clara; Serés, Carme; Torrent-Burgués, Juan

    2015-04-01

    The objective of this work is to apply Atomic Force Microscopy in Peak Force mode to obtain topographic characteristics (mean roughness, root-mean-square roughness, skewness and kurtosis) and mechanical characteristics (adhesion, elastic modulus) of Siloxane-Hydrogel Soft Contact Lenses (CLs) of two different materials, Lotrafilcon B of Air Optix (AO) and Asmofilcon A of PremiO (P), after use (worn CLs). Thus, the results obtained with both materials will be compared, as well as the changes produced by the wear at a nanoscopic level. The results show significant changes in the topographic and mechanical characteristics of the CLs, at a nanoscopic level, due to wear. The AO CL show values of the topographic parameters lower than those of the P CL after wear, which correlates with a better comfort qualification given to the former by the wearers. A significant correlation has also been obtained between the adhesion values found after the use of the CLs with tear quality tests, both break-up-time and Schirmer. PMID:25731094

  8. Structural characterization of sol-gel derived siloxane-oxide materials

    SciTech Connect

    Babonneau, F. [Universite Pierre et Marie Curie, Paris (France); Dire, S. [Univ. di Trento (Italy)

    1993-12-31

    Sol-gel processing of hybrid siloxane-oxide materials is currently widely investigated due to a large amount of potential applications for these systems. They are usually based on silicon alkoxides and derivatives. Various new materials have been prepared combining a modified silicon alkoxide, diethoxydimethylsilane (DEDMS) and a transition metal alkoxide, M(OR){sub n} with M=Ti and Zr. Transparent monolithic pieces or thick films can be obtained over a wide range of compositions. The hydrolysis process of various preparations was followed by {sup 29}Si liquid NMR, and indicates the formation of Si-O-M bonds. The structure of the final gels was essentially characterized by solid state NMR ({sup 1}H, {sup 13}C and {sup 29}Si) and X-ray absorption spectroscopies (Ti K-edge), and leads to propose structural models for these gels. This study points out that titanium and zirconium alkoxides does not only act as cross linking agents, such as silicon alkoxides, but behave as catalysts for the formation of polydimethylsiloxane chains within the materials.

  9. Impressions in type Ib diamond formed at elevated temperature

    NASA Astrophysics Data System (ADS)

    Brookes, E. J.; Daniel, R. D.; Comins, J. D.; Erasmus, R. M.

    The use of the "soft impressor" technique to introduce limited levels of strain in diamond, has allowed the controlled plastic deformation of diamond. This takes the form of multiple intersecting slip, without fracture and can be induced at temperatures less than 0.3 Tm. Linking this technique to optical measurement methods, such as cathodoluminescence (CL) and photoluminescence (PL) spectroscopy [1], gives information concerning the interaction between point defects and dislocations introduced during the impression process. This investigation represents part of a programme designed to provide a more satisfactory understanding of the plasticity in diamond in order to evaluate the mechanical properties and the performance of different types of diamond systems.

  10. Isolation of microRNA from conjunctival impression cytology.

    PubMed

    Pilson, Qistina; Jefferies, Caroline A; Gabhann, Joan Ní; Murphy, Conor C

    2015-03-01

    Impression cytology (IC) is an easy and safe technique that has been used in the past for harvesting epithelial cells from the cornea and conjunctiva for various applications including histology, immunohistology and molecular studies. Previous investigations have shown the usage of different types of membranes for the purpose of investigating pathophysiology and staging of diseases. This contributes to a better understanding of ocular surface conditions and helps to provide information for diagnosis, therapeutic options and prognosis. Recently, there has been a shift of focus in research towards understanding the contribution of microRNAs (miRs) to ocular disease. Thus far, impression cytology has been explored for measuring gene expression but not for quantifying miR expression. This study describes how miRs and mRNA can be isolated from conjunctival epithelial cells obtained by impression cytology and determines the optimum membrane and technique for this purpose. The IC technique was optimized using Biopore, Immobilon-P(SQ) and Millicell Hanging Cell Culture Insert membranes on healthy controls. miRs and mRNAs were isolated from the conjunctival epithelial cells (CEC) obtained and measured. Biopore membrane provided the optimum yield of miRs (38.8 ng/?L ± 10.8) and mRNA (155.3 ng/?L ± 20.1) as well as subjectively found to be best tolerated with minimum discomfort. Appreciable levels of miRs and mRNAs were detected from the CEC from healthy controls, confirming that it is possible to isolate miR and mRNA from CEC. Here, we give a detailed description of the application of conjunctival impression cytology to isolate miRs and the convenience of the technique by using the best membrane available. This method can be readily adopted in both clinical and laboratory settings. This technique will facilitate the measurement of miRs to improve our understanding of the pathogenesis of ocular surface conditions as well as potentially identifying novel therapeutic targets. PMID:25584869

  11. Influence of Blackness on Visual Impression of Color Images

    NASA Astrophysics Data System (ADS)

    Eda, Tetsuya; Koike, Yoshiki; Matsushima, Sakurako; Ishikawa, Tomoharu; Ozaki, Koichi; Ayama, Miyoshi

    Two experiments, using color images of Japanese lacquer objects, investigated the relation between the strength of blackness and the visual and artistic impression of digital color images presented on a display. The first experiment determined the mean RGB values of black surface areas in the test stimuli where observers began to perceive the areas as “black”, and the mean RGB values where observers perceived the areas “really black”. Results indicate that to perceive a “really black” surface, RGB values should be lower than those of the original image in some pictures. The second experiment investigated, how, and to what degree the RGB values of black areas affect the visual impression of an artistic picture. Three factors, “high-quality axis”, “mysterious axis”, and “feeling of material axis”, were extracted by factor analysis. Results indicate that the Art students seem to be more sensitive in the evaluations along the “high-quality axis” and “mysterious axis” than the Engineering students are, while the opposite tendency is observed in the evaluation along the “feeling of material axis”.

  12. In situ self cross-linking of polyvinyl alcohol battery separators

    NASA Technical Reports Server (NTRS)

    Philipp, W. H.; Hsu, L. C.; Sheibley, D. W. (inventors)

    1979-01-01

    A battery separator was produced from a polyvinyl alcohol sheet structure which was subjected to an in situ, self crosslinking process by selective oxidation of the 1,2 diol units present in the polyvinyl alcohol sheet structure. The 1,2 diol units were cleaved to form aldehyde end groups which subsequently crosslink through acetalization of the 1,3 diol units of the polyvinyl alcohol. Selective oxidation was achieved using a solution of a suitable oxidizing agent such as periodic acid or lead tetraacetate.

  13. End-of-life of starch-polyvinyl alcohol biopolymers.

    PubMed

    Guo, M; Stuckey, D C; Murphy, R J

    2013-01-01

    This study presents a life cycle assessment (LCA) model comparing the waste management options for starch-polyvinyl alcohol (PVOH) biopolymers including landfill, anaerobic digestion (AD), industrial composting and home composting. The ranking of biological treatment routes for starch-PVOH biopolymer wastes depended on their chemical compositions. AD represents the optimum choice for starch-PVOH biopolymer containing N and S elements in global warming potential (GWP(100)), acidification and eutrophication but not on the remaining impact categories, where home composting was shown to be a better option due to its low energy and resource inputs. For those starch-PVOH biopolymers with zero N and S contents home composting delivered the best environmental performance amongst biological treatment routes in most impact categories (except for GWP(100)). The landfill scenario performed generally well due largely to the 100-year time horizon and efficient energy recovery system modeled but this good performance is highly sensitive to assumptions adopted in landfill model. PMID:23131650

  14. Diffusion relaxation of photoinduced gratings in polyvinyl acetate latex films

    NASA Astrophysics Data System (ADS)

    Veniaminov, A. V.; Bartsch, E.

    2011-03-01

    The features of the postexposure relaxation of holographic gratings recorded in inhomogeneous polyvinyl acetate latex films with photosensitive agents (photochromic molecules of fulgide dyes and phenanthrenequinone) have been considered. The diffusion coefficients and rms displacements of izomerized probe in polymer latex particles and aqueous environment are determined within the model of two diffusion states. The effective diffusion coefficient of the molecular probe, which is responsible for the relaxation of gratings, increases with an increase in their period in wet films, whereas in dry films, this parameter is independent of the grating period. In the films subjected to high-temperature treatment the effective diffusion coefficient decreases with an increase in the grating period. The successive stages of grating relaxation in latex films with phenanthrenequinone are related to the diffusion of free molecules, radicals, and polymer chains, as well as to the local displacement of macromolecular segments at distances of 5-25 nm.

  15. Incidence of cancer among vinyl chloride and polyvinyl chloride workers.

    PubMed Central

    Heldaas, S S; Langård, S L; Andersen, A

    1984-01-01

    The results of a follow up study of the incidence of cancer and the mortality in a cohort of 454 male workers producing vinyl chloride and polyvinyl chloride are presented. The study population was restricted to employees with more than one year's work experience in the study plant between 1950 and 1969 and the cohort was followed up from 1953 to the end of 1979. Twenty three new cases of cancer were observed compared with 20.2 expected; one case of liver angiosarcoma was found. Five cases of lung cancer were found (2.8 expected) and four cases of malignant melanoma of the skin were observed (0.8 expected). The possibility of a causal relationship between exposure to vinyl chloride and the development of malignant melanomas is discussed. PMID:6691932

  16. Structural insights into enzymatic degradation of oxidized polyvinyl alcohol.

    PubMed

    Yang, Yu; Ko, Tzu-Ping; Liu, Long; Li, Jianghua; Huang, Chun-Hsiang; Chan, Hsiu-Chien; Ren, Feifei; Jia, Dongxu; Wang, Andrew H-J; Guo, Rey-Ting; Chen, Jian; Du, Guocheng

    2014-09-01

    The ever-increasing production and use of polyvinyl alcohol (PVA) threaten our environment. Yet PVA can be assimilated by microbes in two steps: oxidation and cleavage. Here we report novel ?/?-hydrolase structures of oxidized PVA hydrolase (OPH) from two known PVA-degrading organisms, Sphingopyxis sp. 113P3 and Pseudomonas sp. VM15C, including complexes with substrate analogues, acetylacetone and caprylate. The active site is covered by a lid-like ?-ribbon. Unlike other esterase and amidase, OPH is unique in cleaving the C?C bond of ?-diketone, although it has a catalytic triad similar to that of most ?/?-hydrolases. Analysis of the crystal structures suggests a double-oxyanion-hole mechanism, previously only found in thiolase cleaving ?-ketoacyl-CoA. Three mutations in the lid region showed enhanced activity, with potential in industrial applications. PMID:25044912

  17. Influence of Variations in Liquid-Crystalline Content upon the Self-Assembly Behavior of Siloxane-Based Block Copolymers

    SciTech Connect

    Verploegen,E.; Zhang, T.; Murlo, N.; Hammond, P.

    2008-01-01

    A series of well-defined smectic side chain liquid-crystalline (LC) block copolymers with a low glass transition (Tg) siloxane block has been synthesized via anionic polymerization; these systems consist of a glassy polystyrene block and a unique low glass transition temperature LC block based on poly(vinylmethylsiloxane) to which six different LCs have been synthesized and attached. The synthesis techniques used provide systematic control over covalent LC side chain content, allowing for a range of morphologies to be obtained from a single block copolymer backbone during a one-step LC attachment reaction. Variations in the LC structure and content significantly affect the morphology of the LC mesophase, allowing the smectic-to-isotropic transition temperature to be tuned from room temperature up to 150 C. There are two key driving forces in the self-assembly behavior of these materials that are significantly affected by the LC content. The first is the segmental interaction parameter (?) between the blocks, which is a function of the amount of LC attached to the siloxane block. The attachment percent of the LCs to the siloxane block determines the packing density, which affects the stability of the LC mesophase and its interactions with the inter-material dividing surface. The self-assembled morphologies are characterized as a function of LC content and the mechanisms for the observed behavior are detailed. Additional insights into the interactions between the LC and block copolymer mesophases are gained by investigating the morphologies in response to mechanical deformation. The elastic modulus of this system can be tailored over several orders of magnitude by controlling the LC content, and the thermo-mechanical behavior is also highly dependent. The ability to precisely control the degree of LC functionalization enables the custom design and tailoring of material properties for specific applications such as electro-mechanical, damping, and mechano-optical devices.

  18. The effect of different siloxane chain-extenders on the thermal degradation and stability of segmented polyurethanes

    Microsoft Academic Search

    F. S Chuang; W. C Tsen; Y. C Shu

    2004-01-01

    The thermal degradation and stability of siloxane-containing segmented polyurethane and poly(urethane-urea) polymers (OH-SiPU and NH2-SiPU), both prepared from 4,4?-diphenylmethane diisocyanate (MDI), polytetramethylene ether glycol (PTMG) and silicon-containing chain-extenders, have been studied by thermogravimetric analysis (TGA) and Ozawa-Flynn kinetic analysis. The analyses identically revealed that OH-SiPU and NH2-SiPU polymers showed two stages of thermal degradation. The thermal stability and degradation depended

  19. [Application study of optical method in measuring wall thickness of dental impression].

    PubMed

    Mi, Honglin; Wu, Yan; Zheng, Gang

    2014-12-01

    Dental impressions are widely used in the field of oral restoration. The materials are used for making impression in oral cavity. In order to measure the thickness of impression for reference in clinic, the real impressions are taken as the object for studying. Through optical method, charge-coupled device (CCD) is used for collecting the grey image of cutting section of the impressions which are located in the same plane with steel dividing ruler. According to convert relationship between dividing ruler and pixels collecting grey image, the thickness of impression specimens can be obtained. The results show that the optical method used for measuring thickness is feasible to the task and the precision can reach micro dimension. The experiment method and technique can also be provided for measuring thickness of similar tissue engineering materials. PMID:25868235

  20. Proton imaging of siloxanes to map tissue oxygenation levels (PISTOL): a tool for quantitative tissue oximetry†

    PubMed Central

    Kodibagkar, Vikram D.; Wang, Xianghui; Pacheco-Torres, Jesús; Gulaka, Praveen; Mason, Ralph P.

    2011-01-01

    Hexamethyldisiloxane (HMDSO) has been identified as a sensitive proton NMR indicator of tissue oxygenation (pO2) based on spectroscopic spin-lattice relaxometry. A rapid MRI approach has now been designed, implemented, and tested. The technique, proton imaging of siloxanes to map tissue oxygenation levels (PISTOL), utilizes frequency-selective excitation of the HMDSO resonance and chemical-shift selective suppression of residual water signal to effectively eliminate water and fat signals and pulse-burst saturation recovery 1H echo planar imaging to map T1 of HMDSO and hence pO2. PISTOL was used here to obtain maps of pO2 in rat thigh muscle and Dunning prostate R3327 MAT-Lu tumor-implanted rats. Measurements were repeated to assess baseline stability and response to breathing of hyperoxic gas. Each pO2 map was obtained in 3½ min, facilitating dynamic measurements of response to oxygen intervention. Altering the inhaled gas to oxygen produced a significant increase in mean pO2 from 55 Torr to 238 Torr in thigh muscle and a smaller, but significant, increase in mean pO2 from 17 Torr to 78 Torr in MAT-Lu tumors. Thus, PISTOL enabled mapping of tissue pO2 at multiple locations and dynamic changes in pO2 in response to intervention. This new method offers a potentially valuable new tool to image pO2 in vivo for any healthy or diseased state by 1H MRI. PMID:18574806

  1. Optical impression systems for CAD-CAM restorations.

    PubMed

    Galhano, Graziela Ávila Prado; Pellizzer, Eduardo Piza; Mazaro, José Vitor Quinelli

    2012-11-01

    Computer-aided design/computer-aided manufacturing images can be taken through either direct or indirect imaging. For the indirect systems, the digitalization is obtained from the impression material or cast, and for the direct ones the image is taken directly from the mouth using intraoral scanners.The direct acquisition systems have been constantly improved because these are less invasive, quicker, and more precise than the conventional method. Besides, the digital images can be easily stored for a long time. Therefore, the aim of this paper was to describe and discuss based on the literature the main direct image acquisition systems available on the market: CEREC Bluecam (Sirona), Lava C.O.S. System (3M ESPE), iTero System (Cadent/Straumann), and E4D System (D4D Technologies). PMID:23172483

  2. Structural studies of alumina pillared hectorite using polyvinyl alcohol as a pillaring agent

    E-print Network

    Kroenig, Andrea N

    1997-01-01

    In the present work, the structures of a natural hectorite clay pillared with alumina were studied. Frequently, polyvinyl alcohol (PVA) was added as a pillaring agent to observe structural differences in the calcined products. Series of products...

  3. Hydrogen-bonded layer-by-layer assembly of poly(vinyl alcohol) and tannic acid

    E-print Network

    Sample, Caitlin (Caitlin Sarah)

    2014-01-01

    Hydrogen-bonded multilayer thin films containing tannic acid (TA) and poly(vinyl alcohol) (PVA) were assembled under different pH conditions, and film growth and dissolution behavior was assessed through profilometry. ...

  4. Controlling the variable of pressure in the production of test footwear impressions.

    PubMed

    Farrugia, Kevin J; Riches, Philip; Bandey, Helen; Savage, Kathleen; NicDaéid, Niamh

    2012-09-01

    Footwear impression lifting and enhancement techniques may be affected by several variables introduced during the production of test footwear impressions, thus limiting the usefulness of enhancement technique comparisons and the results obtained. One such variable is the force applied when the impressed mark is being made. Producing consistent test impressions for research into footwear enhancement techniques would therefore be beneficial. This study was designed to control pressure in the production of test footwear impressions when mimicking a stamping action. Twenty-seven volunteers were asked to stamp on two different surfaces and the average stamping force was recorded. Information from the data obtained was used to design and build a mechanical device which could be calibrated to consistently deliver footwear impressions with the same force onto a receiving surface. Preliminary experiments using this device and different contaminants on the footwear sole have yielded consistent and repeatable impressions. Controlling the variable of pressure for the production of test impressions in this study demonstrated that the differences observed were visual (due to the amount of contaminant transferred and subsequent enhancement) and did not affect the replication of outer sole characteristics. This paper reports the development of the device and illustrates the quality of the impressions produced. PMID:22841140

  5. Chemical enhancement of footwear impressions in blood on fabric - part 2: peroxidase reagents.

    PubMed

    Farrugia, Kevin J; Savage, Kathleen A; Bandey, Helen; Ciuksza, Tomasz; Nic Daéid, Niamh

    2011-09-01

    This study investigates the optimisation of peroxidase based enhancement techniques for footwear impressions made in blood on various fabric surfaces. Four different haem reagents: leuco crystal violet (LCV), leuco malachite green (LMG), fluorescein and luminol were used to enhance the blood contaminated impressions. The enhancement techniques in this study were used successfully to enhance the impressions in blood on light coloured surfaces, however, only fluorescent and/or chemiluminescent techniques allowed visualisation on dark coloured fabrics, denim and leather. Luminol was the only technique to enhance footwear impressions made in blood on all the fabrics investigated in this study. PMID:21889107

  6. Gelatin-siloxane nanoparticles to deliver nitric oxide for vascular cell regulation: synthesis, cytocompatibility, and cellular responses.

    PubMed

    Zhang, Qin-Yuan; Wang, Zu-Yong; Wen, Feng; Ren, Lei; Li, Jun; Teoh, Swee Hin; Thian, Eng San

    2015-03-01

    Nitric oxide (NO) is an important mediator in cardiovascular system to regulate vascular tone and maintain tissue homeostasis. Its role in vascular cell regulation makes it promising to address the post-surgery restenosis problem. However, the application of NO is constrained by its high reactivity. Here, we developed a novel NO-releasing gelatin-siloxane nanoparticle (GS-NO NP) to deliver NO effectively for vascular cell regulation. Results showed that gelatin-siloxane nanoparticles (GS NPs) could be synthesized via sol-gel chemistry with a diameter of ?200 nm. It could be modified into GS-NO NPs via S-nitrosothiol (RSNO) modification. The synthesized GS-NO NPs could release a total of ?0.12 µmol/mg NO sustainably for 7 days following a first-order exponential profile. They showed not only excellent cytocompatibility, but also rapid intracellularization within 2 h. GS-NO NPs showed inhibition of human aortic smooth muscle cell (AoSMC) proliferation and promotion of human umbilical vein endothelial cell (HUVEC) proliferation in a dose-dependent manner, which is an important approach to prevent restenosis. With GS-NO NP dose at 100 µg/mL, the proliferation of AoSMCs could be slowed down whereas the growth of HUVECs was significantly promoted. We concluded that GS-NO NPs could have potential to be used as a promising nano-system to deliver NO for vascular cell regulation. PMID:24853642

  7. Synthesis and characterization of poly(silyl ether)s and modified poly(siloxane)s

    NASA Astrophysics Data System (ADS)

    Mabry, Joseph Mark

    Activated dihydridocarbonyltris(triphenylphosphine)ruthenium ( Ru) catalyzes the dehydrogenative silylation condensation copolymerization of ortho-quinones with alpha,o-dihydrido-oligodimethylsiloxanes to give high molecular weight copoly(arylene-1,2-dioxy/oligodimethylsiloxanylene)s in good chemical yield. The hydrosilylation polymerization of aliphatic o-dimethylsilyloxy ketones is also catalyzed by activated Ru to yield unsymmetrical poly(silyl ether)s. Likewise, Ru catalyzes the copolymerization of alpha,o-diketones with alpha,o-dihydrido-oligodimethylsiloxanes to yield symmetrical poly(silyl ether)s. A mechanism of the copolymerizations is proposed, in which beta-hydride elimination is favored over reductive elimination in the reaction of the ortho-quinones. Chiral centers affect the NMR spectra of the poly(silyl ether)s produced by hydrosilylation. The photoluminescence properties of the polymers were studied along with those of model compounds. The decrease in Tgs with increase in siloxane chain length as well as fluorescence spectra is discussed. RuH2(CO)(PPh3)3 (Ru), activated with a stoichiometric amount of styrene, catalyzes the anti-Markovnikov addition of an ortho C-H bond of benzophenone across the C-C double bonds of alpha,o-bis(trimethylsilyloxy)copoly(dimethylsiloxane/vinylmethylsiloxane), alpha,o-bis(vinyldimethsilyloxy)poly(dimethylsiloxane)s, and 1,3-divinyltetramethyldisiloxane to yield alpha,o-bis(trimethylsilyloxy)copoly[dimethylsiloxane/2-(2 '-benzophenonyl)ethylmethylsiloxane]s, alpha,o-bis[2-(2 '-benzophenonyl)ethyldimethylsilyloxy]poly(dimethylsiloxane)s, and 1,3-bis[2-(2'-benzophenonyl)ethyl]tetramethyldisiloxane, respectively. While the Mw/Mn and Tgs of the modified polysiloxanes are similar to those of the precursor polymers, an increase in molecular weight is observed upon heating. 1,3-bis[2-(2 '-Benzophenonyl)ethyl]tetramethyldisiloxane, a model compound, was utilized to test a mechanism for the increase in molecular weight. A mechanism is proposed. Fluorinated and non-fluorinated 1,9-bis(epoxyalkyl)pentasiloxanes have been prepared by the Pt-catalyzed hydrosilylation reaction of vinylepoxides with 1,9-dihydridopentasiloxanes. The 1,9-dihydridopentasiloxanes were prepared by the triflic acid-catalyzed ring-opening of the corresponding cyclotrisiloxanes in the presence of 1,1,3,3-tetramethyldisiloxane. Insoluble cross-linked thin films have been prepared by the diaryliodonium salt photo-acid catalyzed ring-opening polymerization of the 1,9-bis(epoxyalkyl)pentasiloxanes. These materials may be useful as anti-corrosion/foul-release coatings for marine applications.

  8. Older and Younger Adults’ First Impressions From Faces: Similar in Agreement but Different in Positivity

    PubMed Central

    Zebrowitz, Leslie A.; Franklin, Robert G.; Hillman, Suzanne; Boc, Henry

    2014-01-01

    People readily form first impressions from faces, with consensual judgments that have significant social consequences. Similar impressions are shown by children, young adults (YA), and people from diverse cultures. However, this is the first study to systematically investigate older adults’ (OA) impressions. OA and YA showed similar levels of within-age agreement in their impressions of competence, health, hostility, and trustworthiness. Both groups also showed stronger within- than between age agreement. Consistent with other evidence for age-related increases in positivity, OA showed more positive impressions of the health, hostility, and trustworthiness of faces. These effects tended to be strongest for the most negatively valenced faces, suggesting that they derive from OA lesser processing of negative cues rather than greater processing of positive cues. An own-age bias in impressions was limited to greater OA positivity in impressions of the hostility of older faces, but not younger ones. Although OA and YA differed in vision and executive function, only OA slower processing speed contributed to age differences in impression positivity. Positivity effects in OA have not been previously linked to processing speed, and research investigating possible explanations for this effect would be worthwhile. PMID:23276216

  9. The Effect of Clothing Variation on First Impressions of Female Job Applicants: What to Wear When.

    ERIC Educational Resources Information Center

    Rucker, M.; And Others

    1981-01-01

    Male and female subjects rated a standardized, professionally drawn female in 12 outfits as to impressions they would make in job interviews. The 12 jobs represented combinations of high- and low-status and male-dominated and female-dominated occupations. Discusses outfits and suggests women made better impressions when applying for…

  10. Firearm recognition based on whole firing pin impression image via backpropagation neural network

    Microsoft Academic Search

    Saadi Bin Ahmad Kamaruddin; Choong-Yeun Liong; Abdul Aziz Jemain

    2011-01-01

    Firearms identification is a vital aim of firearm analysis. The firing pin impression image on a cartridge case from a fired bullet is one of the most significant clues in firearms identification. In this study, a set of data which focused on selected 6 features of firing pin impression images before an entirety of five different pistols of South African

  11. Speed Dating and the Presentation of Self: A Teaching Exercise in Impression Management and Formation

    ERIC Educational Resources Information Center

    Larson, Jeff A.; Tsitsos, William

    2013-01-01

    This article presents an in-class exercise for teaching theories of the presentation of self that is organized around two key concepts, impression management and impression formation. By highlighting the interpretive, interactive aspects of the presentation of self, this exercise is also useful for teaching the major principles of symbolic…

  12. Thermal stability of polyvinyl alcohol/nanocrystalline cellulose composites.

    PubMed

    Voronova, Marina I; Surov, Oleg V; Guseinov, Sabir S; Barannikov, Vladimir P; Zakharov, Anatoly G

    2015-10-01

    Thermal stability of polyvinyl alcohol/cellulose nanocrystals (PVA/CNCs) composites prepared with solution casting technique was studied. The PVA/CNCs composites were characterized by Fourier transform infrared spectrometry, X-ray diffraction, differential scanning calorimeter (DSC) and thermogravimetric (TG) analysis. Due to the presence of CNCs nanoparticles, thermal degradation of the composites occurs at much higher temperatures compared to that of the neat PVA. Thermal stability of the PVA/CNCs composites is maximally enhanced with CNCs content of 8-12 wt%. Some thermal degradation products of the PVA/CNCs composites were identified by mass spectrometric analysis. TG measurements with synchronous recording of mass spectra revealed that the thermal degradation of both CNCs and PVA in the composites with CNCs content of 8-12 wt% occurs simultaneously at a much higher temperature than that of CNCs or the neat PVA. However, with increasing CNCs content more than 12 wt% the thermal stability of the composites decreases. In this case, the degradation of CNCs comes first followed by the degradation of PVA. PMID:26076645

  13. UV-responsive polyvinyl alcohol nanofibers prepared by electrospinning

    NASA Astrophysics Data System (ADS)

    Khatri, Zeeshan; Ali, Shamshad; Khatri, Imran; Mayakrishnan, Gopiraman; Kim, Seong Hun; Kim, Ick-Soo

    2015-07-01

    We report UV-responsive polyvinyl alcohol (PVA) nanofibers for potential application for recording and erasing quick response (QR) codes. We incorporate 1?-3?-dihydro-8-methoxy-1?,3?,3?-trimethyl-6-nitrospiro [2H-1-benzopyran-2,2?-(2H)-indole] (indole) and,3-dihydro-1,3,3-trimethylspiro [2H-indole-2,3?-[3H] phenanthr [9,10-b] (1,4) oxazine] (oxazine) into PVA polymer matrix via electrospinning technique. The resultant nanofibers were measured for recording-erasing, photo-coloration and thermal reversibility. The rate of photo-coloration of PVA-indole nanofibers was five times higher than the PVA-oxazine nanofibers, whereas the thermal reversibility found to be more than twice as fast as PVA-oxazine nanofibers. Results showed that the resultant nanofibers have very good capability of recording QR codes multiple times. The FTIR spectroscopy and SEM were employed to characterize the electrospun nanofibers. The UV-responsive PVA nanofibers have great potentials as a light-driven nanomaterials incorporated within sensors, sensitive displays and in optical devices such as erasable and rewritable optical storage.

  14. Preparation and flammability of poly(vinyl alcohol) composite aerogels.

    PubMed

    Chen, Hong-Bing; Wang, Yu-Zhong; Schiraldi, David A

    2014-05-14

    Poly(vinyl alcohol) (PVOH)-based aerogel composites with nanoscale silica, halloysite, montmorillonite (MMT), and laponite were prepared via a freeze-drying method. The PVOH/MMT and PVOH/laponite composites exhibit higher compressive moduli than the PVOH/SiO2 or PVOH/halloysite samples. Layered microstructures were observed for the samples except with PVOH/laponite, which showed irregular network morphologies. Thermogravimetric analysis of the aerogel samples showed increased thermal stability with the addition of nanofillers. The heat release measured by cone calorimetry, smoke release, and carbon monoxide production of the aerogel composites are all significantly decreased with the addition of nanofillers; these values are much lower than those for commercial expanded polystyrene foam. The fillers did not lead to obvious increases in the limiting oxygen index values, and the corresponding time to ignition values decrease. The ability to adjust the nanofiller levels in these foamlike aerogel composites allows for specific tuning of these products for fire safety. PMID:24731187

  15. Respiratory illness caused by overheating of polyvinyl chloride.

    PubMed

    Froneberg, B; Johnson, P L; Landrigan, P J

    1982-08-01

    On 9 August 1979, 62 (30.8%) of 201 workers and one of 60 management personnel in a polyvinyl chloride (PVC) fabricating plant developed acute upper and lower respiratory irritation, headache, nausea, and fainting. All were taken to hospital; none died. Sixty of the patients were women. Interviews two weeks later with 57 affected and 14 unaffected workers disclosed that illness had followed exposure to fumes from an overheated (362 degrees C) PVC extruding machine. Fumes were emitted from 1100 until 1150; cases occurred from 1100 until late afternoon. All workers who became ill worked west of the overheated extruder, and the affected manager had visited that area. The earliest cases occurred closest to the machine, and incidence decreased (from 53.3% to 15.4%) with distance westward. This pattern was consistent with plant ventilation. Incidence rates in men and women did not differ (p greater than 0.1). At two and 14 weeks, pulmonary function testing of workers with persistent pulmonary symptoms showed abnormalities in 13 of 16 and in 9 of 11 respectively; the group with persistent symptoms contained an excess of non-smokers and of those with previous respiratory illnesses. One kilogram of PVC heated to 300 degrees C releases an estimated 12.9 g of hydrochloric acid (HCl) and 4.9 g of carbon monoxide (CO). We attributed the outbreak to exposure to toxic HCl and CO and rejected the hypothesis of mass psychogenic illness. PMID:7093150

  16. Chemical enhancement of footwear impressions in blood on fabric - part 1: protein stains.

    PubMed

    Farrugia, Kevin J; Savage, Kathleen A; Bandey, Helen; Nic Daéid, Niamh

    2011-09-01

    A range of protein stains were utilised for the enhancement of footwear impressions on a variety of fabric types of different colours with blood as a contaminant. A semi-automated stamping device was used to deliver test impressions at a set force to minimise the variability between impressions; multiple impressions were produced and enhanced by each reagent to determine the repeatability of the enhancement. Results indicated that while most protein stains used in this study successfully enhanced impressions in blood on light coloured fabrics, background staining caused interference on natural fabrics. Enhancement on dark coloured fabrics was only achieved using fluorescent protein stains, as non-fluorescent protein stains provided poor contrast. A further comparison was performed with commercially available protein staining solutions and solutions prepared within the laboratory from the appropriate chemicals. Both solutions performed equally well, though it is recommended to use freshly prepared solutions whenever possible. PMID:21889106

  17. Modification of Fixture Mount to be Used as an Impression Coping in Closely Placed Implants

    PubMed Central

    Jain, Anoop; K, Cauvery; Kumar, Pawan; Havale, Raghavendra

    2014-01-01

    An implant-level impression is often desired for designing and fabricating an implant-supported fixed restoration. This clinical report describes the use of modified press-fit metal implant fixture mount as an impression coping for making an impression of closely placed implants. The fixture mount is easier to manipulate, time saving and more comfortable for both the clinician and patient because the implant fixture mount is connected to the implant by pressing on instead of screwing. As compared to plastic press fit impression coping, metal fixture mount will not distort when modification of fixture mount are required in convergently or closely placed implants. It has the advantage of both the open-tray and closed-tray implant impression techniques. PMID:24959520

  18. A novel method for the photographic recovery of fingermark impressions from ammunition cases using digital imaging.

    PubMed

    Porter, Glenn; Ebeyan, Robert; Crumlish, Charles; Renshaw, Adrian

    2015-03-01

    The photographic preservation of fingermark impression evidence found on ammunition cases remains problematic due to the cylindrical shape of the deposition substrate preventing complete capture of the impression in a single image. A novel method was developed for the photographic recovery of fingermarks from curved surfaces using digital imaging. The process involves the digital construction of a complete impression image made from several different images captured from multiple camera perspectives. Fingermark impressions deposited onto 9-mm and 0.22-caliber brass cartridge cases and a plastic 12-gauge shotgun shell were tested using various image parameters, including digital stitching method, number of images per 360° rotation of shell, image cropping, and overlap. The results suggest that this method may be successfully used to recover fingermark impression evidence from the surfaces of ammunition cases or other similar cylindrical surfaces. PMID:25537854

  19. Measuring turbulent gust impressions in a forested canopy

    NASA Astrophysics Data System (ADS)

    Hiscox, A.; Ertell, K.

    2014-12-01

    The temporal and spatial characteristics of tree-sway motions and their aerodynamic interactions with coherent turbulence wind fields in a forest (Howland Forest, ME) are examined. Year round measurements of turbulence where taken at heights, above, below, and in the live crown. Additionally measurements of tree bole motion were taken simultaneously for 150 trees surrounding the main meteorological tower. To identify the gust impressions and further understand the timing, spacing and intensity of momentum flux, a a multi-resolution decomposition (MRD) technique was used to find the dominant eddy size. Fourier analysis was applied to each tree for the corresponding time and changes in dominant tree frequency were mapped over time. Results indicate that the most coherency in stand-scale motion occurs when frequency changes are mapped at the same time resolution of the dominant eddy size. Through a mapping-displacement comparison, the sub-mesoscale motions of a canopy atmosphere and their effect on the tree's movement as well as fluxes of energy will be better understood.

  20. How shadows shape our impression of rough surfaces

    NASA Astrophysics Data System (ADS)

    Salami, M.; Hajian, A.; Fazeli, S. M.; Vasheghani Farahani, S.; Jafari, G. R.

    2014-12-01

    The aim here is to shape our impression of rough surfaces based on the formation of shadows. The shadows blackout some parts of the surface leading us to state that rough surfaces are not always quite the way they seem. In fact, it is the angle of view that proves the size of the shadows. In surface profilometry, the scanned image is produced by a vertical shot. While in nature, a vertical sighting of events is not always possible or preferred, therefore readings by various observers would depend on the angle of their line of sight. In the present work, owing to the statistical properties of rough surfaces, the relation between a vertical and angular line of site view of a surface is obtained. This enables the estimation of how the surface really looks like, even though the observer has an non vertical line of sight. To be most illustrative, a comparison between wave scattering from an actual surface and that from an observed surface is performed. The shadowing effects which are shown to be inversely proportional to the Hurst exponent, cause the height correlation function to posses a bi-scaling behaviour. We also illustrate how the correlation develops its efficiency as the line of sight angle tends to zero, making the surface look smooth.

  1. Lateral orbitofrontal cortex links social impressions to political choices.

    PubMed

    Xia, Chenjie; Stolle, Dietlind; Gidengil, Elisabeth; Fellows, Lesley K

    2015-06-01

    Recent studies of political behavior suggest that voting decisions can be influenced substantially by "first-impression" social attributions based on physical appearance. Separate lines of research have implicated the orbitofrontal cortex (OFC) in the judgment of social traits on the one hand and economic decision-making on the other, making this region a plausible candidate for linking social attributions to voting decisions. Here, we asked whether OFC lesions in humans disrupted the ability to judge traits of political candidates or affected how these judgments influenced voting decisions. Seven patients with lateral OFC damage, 18 patients with frontal damage sparing the lateral OFC, and 53 matched healthy participants took part in a simulated election paradigm, in which they voted for real-life (but unknown) candidates based only on photographs of their faces. Consistent with previous work, attributions of "competence" and "attractiveness" based on candidate appearance predicted voting behavior in the healthy control group. Frontal damage did not affect substantially the ability to make competence or attractiveness judgments, but patients with damage to the lateral OFC differed from other groups in how they applied this information when voting. Only attractiveness ratings had any predictive power for voting choices after lateral OFC damage, whereas other frontal patients and healthy controls relied on information about both competence and attractiveness in making their choice. An intact lateral OFC may not be necessary for judgment of social traits based on physical appearance, but it seems to be crucial in applying this information in political decision-making. PMID:26041918

  2. Psychotic patients' impressions of a person from written descriptions.

    PubMed

    Luchins, A S; Luchins, E H

    1984-02-01

    The present study examined the impressions of personality formed from written descriptions of behavior by over 200 hospitalized male schizophrenics, tested individually when they seemed in contact with reality. One description was of extrovert (E) behavior by a youth named Jim; another was of his introvert (I) behavior in similar settings. Combined communications gave one description immediately after the other. After 150 patients read one of the communications, they were generally willing and able to respond to a 36-item questionnaire about Jim. This also occurred when 96 patients were asked to answer it before any communication, on the basis of their expectations about Jim; 56 subsequently received a communication, followed by readministration of the questionnaire. Patients' responses, before or after the communications, revealed few pathological signs and, like those of normal Ss, could usually be classified as E or I. Patients had less differential effects, and far fewer I responses than normal Ss. Patients and normals showed preconceptions of Jim as extrovertive. Results were discussed in light of the projective hypothesis and other theories. PMID:6706109

  3. Fertilizing ROSES through the STEM: Interdisciplinary Modules as Pre-service Research Experiences for Secondary STEM Educators (IMPRESS-Ed)

    NASA Astrophysics Data System (ADS)

    Magee, N. B.; Kavic, M.; Benoit, M. H.; Wiita, P.

    2011-12-01

    IMPRESS-Ed is a program designed to provide authentic summer research experiences in the space, earth, and atmospheric sciences for pre-service K-12 educators at The College of New Jersey (TCNJ). In 2011, the program involved five students and took place over eight weeks with recruitment occurring during the preceding academic year. The program was divided into two modules: A common core module and an individual mentored research experience. The common module consisted of three units focusing on data-driven pedagogical approaches in astrophysics, tectonophysics, and atmospheric science, respectively. The common module also featured training sessions in observational astronomy, and use of a 3D geowall and state of the art planetarium. Participants in the program are also offered the opportunity to utilize the available TCNJ facilities with their future students. Given that a large number of graduates from the TCNJ take positions in local New Jersey schools, the opportunity to make use of these facilities at a future time would be of great significance to them and their future students. The individual mentored research module matched student interests with potential projects. Research led by M.H. Benoit analyzed gravity data from the NASA-GRACE mission to find lithospheric density contrasts beneath the eastern US. A student working with N.B. Magee used data from NASA satellites CALIPSO, CloudSat, and AQUA-MODIS to study the dynamics of convective cloud tops. Research projects led by M. Kavic performed simulations to investigate the possibility of detecting superconducting cosmic strings using radio observations and also designed and constructed a radio interferometer based on the NASA's Radio-Jove program. P. Wiita supervised a research project studying star-forming regions of active galaxies through analysis of images from NASA's Hubble Space Telescope and GALEX. The research program was also incorporated into the framework of the TCNJ Mentored Undergraduate Summer Experience (MUSE), which provided weekly seminars and community-building activities for approximately 85 undergraduate summer researchers. This program concludes with a large research symposium in which all participants present the results of their research efforts. Initial evaluation of the program was highly positive. All five students demonstrated strong gains in earth and space science literacy compared to a baseline measurement. Each student also reported gaining confidence to incorporate data and research-driven instruction in the space and earth sciences into the K-12 STEM classroom setting. All five research projects were also quite successful: several of the students plan to continue research during the academic year and two students are presenting research findings as first authors here at AGU. Other research results are likely to be presented at this year's American Astronomical Society meeting.

  4. An evaluation of dimensional accuracy of one-step and two-step impression technique using addition silicone impression material: an in vitro study.

    PubMed

    Pande, Neelam A; Parkhedkar, R D

    2013-09-01

    The study is aimed to evaluate the dimensional accuracy, the effect of undercut of two different configurations and the elastic recovery of addition silicone impression material assessed indirectly, by measuring the dimensions on stone models recorded from the impression of the master model, using one-step and two-step impression technique, for addition silicone impression materials. Measurements are taken to evaluate horizontal or linear and vertical dimensional changes, of the abutment V and abutment C from the stainless steel model. Heavy body/light body material is used for making one-step impression technique in a custom tray. Putty/light body is used for taking two-step technique in a stock metal tray. Improved die stone is used for pouring the impression. The different 11 locations on the dies produced by two different techniques are measured microscopically on image analyzer and compared with those of stainless steel model. Anova test was applied to test the differences of mean values of inter and intra abutment measurements, to calculate p value. Unpaired t test was applied to calculate t value. Results showed less deviation of stone models produced by one-step technique from stainless steel model, whereas the deviation of stone models produced by two-step is comparatively more. (p < 0.01). This difference of deviation is significantly less in one-step as compared to two-step technique. One-step is sufficiently dimensionally accurate than two-step technique in conjunction with addition silicone impression material. They have the best elastic recovery from the two undercut configurations. PMID:24431743

  5. New holographic polymeric composition based on plexiglass, polyvinyl butyral, and phenanthrenquinone

    NASA Astrophysics Data System (ADS)

    Matusevich, Vladislav; Tolstik, Elen; Kowarschik, Richard; Egorova, Elena; Matusevich, Yuri I.; Krul, Leonid

    2013-05-01

    The newly developed Plexiglas films containing polyvinyl butyral resins and phenanthrenequinone molecules as photosensitive dopant, which are proposed for the practical application as interlayer of laminated safety glass, are shown for the first time. The injection of the phenanthrenequinone-poly(methyl methacrylate) into the polyvinyl butyral protective interlayer provides a homogenous distribution of the recording holographic medium in the layer and allows fixing the entire surface grating in the laminated glass. In addition, the original properties of polyvinyl butyral as a connecting material were preserved during manufacturing of the laminated glass. This allows a recording of holographic structures directly after baking of the laminated glass, thus reducing the destruction of the gratings due to the elevated temperatures. The diffractive structures in phenanthrenequinone-poly(methyl methacrylate)-polyvinyl butyral polymeric layers with thicknesses of hundreds of microns are sealed between two panels of glass (so-called laminated glass) and are generated by illumination with an Argon-laser of 514 nm. Efficiently fixed and long-term stable holographic gratings recorded in the phenanthrenequinone-poly(methyl methacrylate)-polyvinyl butyral layer enable to produce transparent laminated glass with inserted diffractive elements, which can be used e.g. for Head-up Displays in automobile windshields or as holographic light concentrators for solar cells.

  6. Conjunctival impression cytology in non-proliferative and proliferative diabetic retinopathy

    PubMed Central

    Citirik, Mehmet; Berker, Nilufer; Haksever, Hulya; Elgin, Ufuk; Ustun, Huseyin

    2014-01-01

    AIM To examine the integrity of the ocular surfaces of subjects with and without diabetes with no conjunctival and dry eye signs and symptoms and compare conjunctival impression cytology findings in diabetics with non-proliferative and proliferative diabetic retinopathy. METHODS Conjunctival impression cytology was performed on 43 eyes of 43 subjects with non-proliferative diabetic retinopathy (NPDR), 42 eyes of 42 subjects with proliferative diabetic retinopathy (PDR), and 30 eyes of 30 control subjects. Impression cytology specimens of each group were graded and scored in the range 0-3 according to Nelson's method. RESULTS There were 45 (52.9%) women and 40 (47.1%) men. The mean age of the patients was 59.6±9.3y (range, 43-76y) in NPDR group and 58.0±8.8y (range, 41-85y) in PDR group. Cases with NPDR and PDR showed statistically significant higher impression cytology scores than control group (P<0.05). There was no difference between the NPDR and PDR patients for impression cytology grading scores. CONCLUSION It is determined that impression cytology grades are altered in patients with NPDR and PDR. Consequently, we suggest that there might be an association between the impression cytology grading scores and the severity of diabetic retinopathy PMID:24790878

  7. Surface Alignment, Anchoring Transitions, Optical Properties, and Topological Defects in the Thermotropic Nematic Phase of an Organo-Siloxane Tetrapodes

    E-print Network

    Young-Ki Kim; Bohdan Senyuk; Sung-Tae Shin; Alexandra Kohlmeier; Georg H. Mehl; Oleg D. Lavrentovich

    2013-11-02

    We perform optical, surface anchoring, and textural studies of an organo-siloxane tetrapode material in the broad temperature range of the nematic phase. The optical, structural, and topological features are compatible with the uniaxial nematic order rather than with the biaxial nematic order, in the entire nematic temperature range -25C < T < 46C studied. For homeotropic alignment, the material experiences surface anchoring transition, but the director can be realigned into an optically uniaxial texture by applying a sufficiently strong electric field. The topological features of textures in cylindrical capillaries, in spherical droplets and around colloidal inclusions are consistent with the uniaxial character of the long-range nematic order. In particular, we observe isolated surface point defect-boojums and bulk point defects-hedgehog that can exist only in the uniaxial nematic.

  8. Surface Alignment, Anchoring Transitions, Optical Properties, and Topological Defects in the Thermotropic Nematic Phase of an Organo-Siloxane Tetrapodes

    E-print Network

    Kim, Young-Ki; Shin, Sung-Tae; Kohlmeier, Alexandra; Mehl, Georg H; Lavrentovich, Oleg D

    2013-01-01

    We perform optical, surface anchoring, and textural studies of an organo-siloxane tetrapode material in the broad temperature range of the nematic phase. The optical, structural, and topological features are compatible with the uniaxial nematic order rather than with the biaxial nematic order, in the entire nematic temperature range -25C < T < 46C studied. For homeotropic alignment, the material experiences surface anchoring transition, but the director can be realigned into an optically uniaxial texture by applying a sufficiently strong electric field. The topological features of textures in cylindrical capillaries, in spherical droplets and around colloidal inclusions are consistent with the uniaxial character of the long-range nematic order. In particular, we observe isolated surface point defect-boojums and bulk point defects-hedgehog that can exist only in the uniaxial nematic.

  9. Surface alignment, anchoring transitions, optical properties, and topological defects in the thermotropic nematic phase of organo-siloxane tetrapodes.

    PubMed

    Kim, Young-Ki; Senyuk, Bohdan; Shin, Sung-Tae; Kohlmeier, Alexandra; Mehl, Georg H; Lavrentovich, Oleg D

    2014-01-21

    We perform optical, surface anchoring, and textural studies of an organo-siloxane "tetrapode" material in the broad temperature range of the nematic phase. The optical, structural, and topological features are compatible with the uniaxial nematic order rather than with the biaxial nematic order, in the entire nematic temperature range -25 °C < T < 46 °C studied. For homeotropic alignment, the material experiences surface anchoring transition, but the director can be realigned into an optically uniaxial texture by applying a sufficiently strong electric field. The topological features of textures in cylindrical capillaries, in spherical droplets and around colloidal inclusions are consistent with the uniaxial character of the long-range nematic order. In particular, we observe isolated surface point defects - boojums and bulk point defects - hedgehogs that can exist only in the uniaxial nematic liquid crystal. PMID:24651889

  10. Impression techniques and misfit-induced strains on implant-supported superstructures: an in vitro study.

    PubMed

    Cehreli, Murat C; Akça, Kivanç

    2006-08-01

    The purpose of this study was to compare misfit-induced strains on implant-supported superstructures fabricated by two impression techniques and two different elastomeric impression materials. A master cast hosting four Straumann implants was constructed. On this cast, a total of 21 implant-level impressions were made by the direct technique using a polyether impression material and synOcta screwed aluminum impression caps (PE-D), and by the indirect technique using polyether (PE-IN) or polyvinylsiloxane impression material (VPS-IN) with snap-on impression caps and synOcta plastic positioning cylinders. Two casts were randomly selected from each group of seven, and a total of four screw-retained superstructures, supported by either two or four implants (one of each type on both casts), were cast in a gold alloy for each group. Linear strain gauges were bonded on the superstructures, and misfit-induced strains were recorded during superstructure connection on each of the working casts and on the master cast using a data acquisition system and corresponding software at a sample rate of 10 kHz. Connection on the implants in the master cast increased strains considerably on most of the superstructures, in comparison with strain gradients measured when the superstructures were connected on the casts from which they were fabricated (P <.05). The differences in strain amplitude between connection on the cast from which the superstructure was fabricated and on the master cast were higher for superstructures fabricated by PE-D than for those fabricated by PE-IN and VPS-IN. The snap-on indirect impression technique for Straumann implants leads to acceptable superstructures, regardless of the impression material used. PMID:16939020

  11. Basilar impression complicating osteogenesis imperfecta type IV: the clinical and neuroradiological findings in four cases

    PubMed Central

    Hayes, M; Parker, G; Ell, J; Sillence, D

    1999-01-01

    OBJECTIVES—To describe the clinical and neuroradiological features of basilar impression in patients with osteogenesis imperfecta type IV.?METHODS—Four patients with basilar impression were ascertained in a population study of osteogenesis imperfecta. All four had detailed clinical and neuroradiological examination with both CT and MRI of the craniocervical junction andposterior fossa structures.?RESULTS—All four showed significant compression of the posterior fossa structures and surgical decompression was performed with relief of symptoms.?CONCLUSION—Symptoms of cough headache and trigeminal neuralgia occurring in patients with osteogenesis imperfecta are indications for detailed clinical and neuroradiological investigation to document basilar impression.?? PMID:10084535

  12. Examining the Moderating Effect of Appearance Impression Motivation on the Relationship between Perceived Physical Appearance and Social Physique Anxiety

    ERIC Educational Resources Information Center

    Amorose, Anthony J.; Hollembeak, Jill

    2005-01-01

    Despite the conceptual importance of impression motivation in predicting social anxiety (Leary & Kowalski, 1995; Schlenker & Leary, 1982), no research has tested the link between impression motivation specifically regarding one's physical appearance (appearance impression motivation, or AIM) and social physique anxiety (SPA). The purpose of this…

  13. Hot Pin Welding of Thin Poly(vinyl chloride) Sheet James D. Van de Ven, Arthur G. Erdman

    E-print Network

    Van de Ven, James D.

    Hot Pin Welding of Thin Poly(vinyl chloride) Sheet James D. Van de Ven, Arthur G. Erdman Mechanical of welding two thin sheets of poly(vinyl chloride) (PVC) with a heated pin, thus allowing construction of a relationship between the weld temperature and weld strength. Constructing a relationship between weld strength

  14. Effect of Hydroxyl Concentration on Chemical Sensitivity of Polyvinyl Alcohol/Carbon-Black Composite Chemiresistors

    SciTech Connect

    Hughes, Robert C.; Patel, Sanjay V.; Yelton, W. Graham

    1999-05-19

    The sensitivity and selectivity of polyvinyl alcohol (PVA) / carbon black composite films have been found to vary depending upon the hydroxylation percentage ("-OH") of the polymer. These chemiresistors made from PVA films whose polymer backbone is 88% hydroxylated (PVA88) have a high sensitivity to water, while chemiresistors made from PVA75 have a higher sensitivity to methanol. The minor differences in polymer composition result in films with different Hildebrand volubility parameters. The relative responses of several different PVA-based chemiresistors to solvents with different volubility parameters are presented. In addition, polyvinyl acetate (PVAC) films with PVA88 are used in an array to distinguish the responses to methanol-water mixtures.

  15. Simulation of the high temperature impression of thermal barrier coatings with columnar microstructure

    E-print Network

    Hutchinson, John W.

    Simulation of the high temperature impression of thermal barrier coatings with columnar of thermal barrier coatings (TBCs) are affected by their high temperature mechanical properties: especially rights reserved. Keywords: Thermal barrier coating; Indentation; Columnar microstructure 1. Introduction

  16. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices...topographical characteristics of teeth, dental impressions, or stone models...computer-assisted design and manufacturing of dental restorative prosthetic...

  17. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices...topographical characteristics of teeth, dental impressions, or stone models...computer-assisted design and manufacturing of dental restorative prosthetic...

  18. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices...topographical characteristics of teeth, dental impressions, or stone models...computer-assisted design and manufacturing of dental restorative prosthetic...

  19. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices...topographical characteristics of teeth, dental impressions, or stone models...computer-assisted design and manufacturing of dental restorative prosthetic...

  20. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices...topographical characteristics of teeth, dental impressions, or stone models...computer-assisted design and manufacturing of dental restorative prosthetic...

  1. Machivellian Effects on the Ability to Impression Manage and Judge Personality in INterview Situations 

    E-print Network

    Meldrum, Jerome

    2008-06-27

    Research has established that when asked to fill out self-report personality inventories, participants are able to impression manage their answers in a desired direction in laboratory and real life settings. Research has ...

  2. Effects of reheating on the accuracy of addition silicone putty-wash impressions.

    PubMed

    Tjan, A H; Li, T

    1991-06-01

    The effect of the relatively high thermal contraction of addition silicones (polyvinylsiloxane) on the accuracy of stone casts was evaluated using the putty/wash relining impression technique and acrylic resin trays. Impressions were made at 37 degrees C and were divided into two groups. One group was poured at room temperature (22 degrees +/- 2 degrees C) and another group was reheated to 37 degrees C before pouring. Measurement of the dimensional changes failed to reveal improved accuracy of the stone casts poured at the same temperature as that reached during impression making. On the basis of this limited sample, it can be concluded that reheating the impression using the putty/wash relining technique did not improve the accuracy of the stone cast. PMID:2072314

  3. Vision expert system 3D-IMPRESS for automated construction of three dimensional image processing procedures

    Microsoft Academic Search

    Xiang-Rong Zhou; Akinobu Shimizu; Jun-ichi Hasegawa; Jun-ichiro Toriwaki; Takeshi Hara; Hiroshi Fujita

    2001-01-01

    In this paper a three dimensional (3D) image processing expert system called 3D-IMPRESS is presented. This system can automatically construct a 3D image processing procedure by using pairs of an original input image and a desired output figure called sample figure given by a user This paper describes the outline of 3D-IMPRESS and presents a method of procedure consolidation for

  4. Exceptional stegosaur integument impressions from the Upper Jurassic Morrison Formation of Wyoming

    Microsoft Academic Search

    Nicolai A. Christiansen; Emanuel Tschopp

    2010-01-01

    Dinosaur skin impressions are rare in the Upper Jurassic Morrison Formation, but different sites on the Howe Ranch in Wyoming\\u000a (USA), comprising specimens from diplodocid, camarasaurid, allosaurid and stegosaurian dinosaurs, have proven to be a treasure-trove\\u000a for these soft-tissue remains. Here we describe stegosaurian skin impressions from North America for the first time, as well\\u000a as the first case of

  5. First impressions: title design and story introduction in the film industry 

    E-print Network

    Messinger, Christina Rene

    2002-01-01

    FIRST IMPRESSIONS: TITLE DESIGN AND STORY INTRODUCTION IN T H E FILM INDUSTRY A Thesis by CHRISTINA R E N E MESSINGER Submitted to the Office of Graduate Studies of Texas A & M University in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE December 2002 Major Subject: Visualization Sciences FIRST IMPRESSIONS: TITLE DESIGN AND STORY INTRODUCTION IN T H E FILM INDUSTRY A Thesis by CHRISTINA R E N E MESSINGER Submitted to Texas A & M University in partial...

  6. Effect of temperature changes on the dimensional stability of elastomeric impression materials

    PubMed Central

    Kambhampati, Sujan; Subhash, Vaddavalli; Vijay, Chellagulla; Das, Aruna

    2014-01-01

    Background: The purpose of this study was to evaluate the changed dimensions of dies obtained from impressions made with different combinations of addition sillicones which were subjected to variations in storage temperature. Materials & Methods: 45 die stone models were obtained of 45 impressions of which 15 each were stored at three different storage temperatures(25°C, 37°C and 42°C). 15 impressions each were made using one impression technique. The measurements of the dies made from the impressions were measured with the help of Profile Projector with a accuracy of 0.001mm. Results: The results were statistically analyzed. The results indicated the significant decrease in dimensions when the storage temperature reduced from the mouth temperature. As compared to this there was a marginal increase in overall dimensions of all variables when storage temperature increased. Conclusion: More changes were seen in putty/light body combination followed by monophase and least in heavy/light body combination. How to cite the article: Kambhampati S, Subhash V, Vijay C, Das A. Effect of temperature changes on the dimensional stability of elastomeric impression materials. J Int Oral Health 2014;6(1):12-9. PMID:24653597

  7. Hydrogels based on poly(ethylene oxide) and poly(tetramethylene oxide) or poly(dimethyl siloxane): synthesis, characterization, in vitro protein adsorption and platelet adhesion

    Microsoft Academic Search

    Jae Hyung Park; You Han Bae

    2002-01-01

    In vitro protein adsorption, platelet adhesion and activation on new hydrogel surfaces, composed of poly(ethylene oxide) (PEO) and poly(tetramethylene oxide) (PTMO) or poly(dimethyl siloxane) (PDMS), were investigated. By varying PEO length (MW=2000 or 3400), hydrophobic components (PTMO or PDMS) or polymer topology (block or graft copolymers), various physical hydrogels were produced. Their structures were verified by 1HNMR and ATR-IR and

  8. Function and performance of silicone copolymer. Part IV. Curing behavior and characterization of epoxy–siloxane copolymers blended with diglycidyl ether of bisphenol-A

    Microsoft Academic Search

    Sheng-Shu Hou; Yen-Pin Chung; Cheng-Kuang Chan; Ping-Lin Kuo

    2000-01-01

    In this research, a siloxane-type epoxy resin (SG copolymer), which has pendant epoxide rings on the side chain of the polysiloxane polymer backbone, was synthesized by the hydrosilylation reaction of poly(methylhydrosiloxane) with allyl glycidyl ether. The polymer structures were characterized by 1H NMR. The SG resin was then blended with a commercial epoxy resin (diglycidyl ether of bisphenol-A, DGEBA) at

  9. Corrosion resistance of siloxane-poly(methyl methacrylate) hybrid films modified with acetic acid on tin plate substrates: Influence of tetraethoxysilane addition

    NASA Astrophysics Data System (ADS)

    Kunst, S. R.; Cardoso, H. R. P.; Oliveira, C. T.; Santana, J. A.; Sarmento, V. H. V.; Muller, I. L.; Malfatti, C. F.

    2014-04-01

    The aim of this paper is to study the corrosion resistance of hybrid films. Tin plate was coated with a siloxane-poly (methyl methacrylate) (PMMA) hybrid film prepared by sol-gel route with covalent bonds between the organic (PMMA) and inorganic (siloxane) phases obtained by hydrolysis and polycondensation of 3-(trimethoxysilylpropyl) methacrylate (TMSM) and polymerization of methyl methacrylate (MMA) using benzoyl peroxide (BPO) as a thermic initiator. Hydrolysis reactions were catalyzed by acetic acid solution avoiding the use of chlorine or stronger acids in the film preparation. The effect of the addition of tetraethoxysilane (TEOS) on the protective properties of the film was evaluated. The hydrophobicity of the film was determined by contact angle measurements, and the morphology was evaluated by scanning electron microscopy (SEM) and profilometry. The local nanostructure was investigated by Fourier transform infrared spectroscopy (FT-IR). The electrochemical behavior of the films was assessed by open circuit potential monitoring, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements in a 0.05 M NaCl solution. The mechanical behavior was evaluated by tribology. The results highlighted that the siloxane-PMMA hybrid films modified with acetic acid are promising anti-corrosive coatings that acts as an efficient diffusion barrier, protecting tin plates against corrosion. However, the coating properties were affected by the TEOS addition, which contributed for the thickness increase and irregular surface coverage.

  10. Poly(vinyl alcohol)-based buffering membranes for isoelectric trapping separations 

    E-print Network

    Craver, Helen C.

    2009-05-15

    exposed to high concentrations of acid and base due to hydrolysis of the amide bonds. Poly(vinyl alcohol)-based, or PVA-based, membranes were made as an alternative to the polyacrylamide-based membranes since they provide more hydrolytic and mechanical...

  11. Silastic Molding Method for Pectus Excavatum Correction Using a Polyvinyl Alcohol (Ivalon) Sponge

    PubMed Central

    Lee, Jun-Ho; Kim, Sung-Jin; Chung, Won-Sang; Kim, Hyuck; Chon, Soon-Ho

    2012-01-01

    Pectus excavatum is rare, but it is the most common type of sternal congenital disorder. There are many surgical methods to correct pectus excavatum such as the Ravitch method, Wada method, Silastic mold method, and the Nuss operation. We report a case of minimal invasive surgery for pectus excavatum using a polyvinyl alcohol sponge. PMID:23275928

  12. Poly(vinyl chloride)\\/clay nanocomposites: X-ray diffraction, thermal and rheological behaviour

    Microsoft Academic Search

    T. Peprnicek; J. Duchet; L. Kovarova; J. Malac; J. F. Gerard; J. Simonik

    2006-01-01

    The paper concentrates on poly(vinyl chloride) – PVC – from the point of view of structural characterisation of PVC\\/clay nanocomposites through X-ray diffraction, thermogravimetric analysis and dynamic rheometric analysis. PVC plasticizer was mixed with clay, natural and organophilic, and the suspension was then compounded with other components. Two factors were followed: effect of shearing alone, and in combination with temperature.

  13. Controlling the color of Lippmann holograms recorded in dichromated gelatin polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Cai, Tiequan; Tang, Yixing; Wang, Hui; Dai, Chaoming; Guo, Lurong

    1993-03-01

    The polyvinyl alcohol and several other organic materials are mixed into the aqueous gelatin while the film is coated. This thin solid film is sensitized by aqueous ammonium dichromate, so it is called a dichromated gelatin polyvinyl alcohol (DC-GPVA) holographic recording material. DC-GPVA not only possesses the same excellent holographic properties as the conventional dichromated gelatin (DCG) but also obviously improves its environmental stability. Experimental results have shown that the reconstruction wavelength of a Lippman hologram recorded in DC-GPVA can be shifted to longer or shorter wavelengths and freely controlled to a certain extent by varying the ratio of the gelatin and the polyvinyl alcohol and relative organic materials, or hardeners and its quantity, or heated temperature and heated time exerted on the drying films, or thickness of them. After the films are sensitized, they can be exposed by He-Cd or Ar+ laser (441.6 nm or 488.0 nm) and developed by the regular post processed method. Initial discussions are also presented about the functions and mechanisms of the polyvinyl alcohol and relative organic materials added into DC-GPVA.

  14. Oxidative mineralization and characterization of polyvinyl alcohol for compatibility with tank farm processing chemistry

    SciTech Connect

    Oji, L.N.

    2000-01-04

    Polyvinyl alcohol (PVA) material has been evaluated for use as a cost-effective substitute for conventional cellulose-based disposal materials (decontamination mops and wipes), plastic bags, and disposable personal protection clothing, that are currently used at Savannah River Site. This study also provides process design criteria for ultraviolet/ultrasonic/hydrogen peroxide PVA reactor system.

  15. Removal of total organic carbon from aqueous solution containing polyvinyl alcohol by electrocoagulation technology

    Microsoft Academic Search

    Wei-Lung Chou; Chih-Ta Wang; Chia-Wei Hsu; Kai-Yu Huang; Te-Chao Liu

    2010-01-01

    The removal of total organic carbon (TOC) from aqueous solution containing polyvinyl alcohol (PVA) using iron electrocoagulation (EC) was investigated. Iron hydroxides generated during EC were used to remove PVA and TOC from the aqueous solution, and the effects of varying current density and solution temperature on PVA and TOC adsorption characteristics were evaluated. The findings indicated that complete PVA

  16. Compatibility of Polyvinyl Alcohol with the 241-F/H Tank Farm Liquid Waste

    SciTech Connect

    Oji, L.N.

    1998-11-25

    This report describes results from laboratory-scale oxidative mineralization of polyvinyl alcohol (PVA), and the evaluation of the F/H Tank Farms as a storage/disposal option for PVA waste solution generated in the Canyons and B-line decontamination operations.

  17. DSC, TGA and dielectric properties of carboxymethyl cellulose\\/polyvinyl alcohol blends

    Microsoft Academic Search

    S. El-Sayed; K. H. Mahmoud; A. A. Fatah; A. Hassen

    2011-01-01

    Films with different compositions of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) blends have been prepared using the casting method. Differential scanning calorimetery (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy of all compositions have been investigated. It was found that PVA and CMC are compatible in the studied range of composition. With increasing CMC content, the thermal stability of PVA

  18. Radiation Synthesis and Characterization of Hydrogels Composed of Poly(vinyl alcohol) and Acrylamide Mixtures

    Microsoft Academic Search

    Safaa G. Abd Alla

    2007-01-01

    Hydrogels based on various compositions of poly(vinyl alcohol) (PVA) and acrylamide (AM) monomer were produced under the effect of ??irradiation. The hydrogels were characterized by IR spectroscopy and thermogravimetric analysis (TGA). In addition, the effect of temperature and pH on the swelling behavior was studied. It was proved that the composition of the final product corresponds to the initial composition

  19. [Preparation and clinical application of polyvinyl alcohol/drug-loaded chitosan microsphere composite wound dressing].

    PubMed

    Zhang, Xiuju; Lin, Zhidan; Chen, Wenbin; Song, Ying; Li, Zhizhong

    2011-04-01

    In order to prepare and apply the polyvinyl alcohol/drug-loaded chitosan microspheres composite wound dressing, we first prepared chitosan microspheres by emulsion cross-linking method, and then added chitosan microspheres into the reactants during the acetalization of polyvinyl alcohol and formaldehyde. We further studied the morphology, water absorption, swelling degree, mechanical properties and in vitro release of the sponge with different amount of chitosan microspheres. The results showed that polyvinyl alcohol/drug-loaded chitosan composite sponge has porous structure with connectionism. Increasing the amount of chitosan microspheres would make the apertures smaller, so that the water absorption and the swelling of sponge decreased, but the tensile strength and compressive strength increased. With the increase of the amount of chitosan microspheres, the drug absorption of cefradine and the release rate increase, and the release time become longer. With the results of toxicity grade of 0 to 1, this type of composite sponge is non-toxic and meets the requirement of biocompatibility. The observation of rabbit nasal cavity after surgical operation suggested that polyvinyl acetal sponge modified with the chitosan has antiphlogistic, hemostatic and non-adherent characteristic, and can promote the healing and recovering of the nasalmucosa. After using this composite material, best growing surroundings for patients' granulation tissue were provided. Exposed bone and tendon were covered well with granulation tissue. PMID:21604506

  20. Phase separation in the solution of water glass and poly(vinyl alcohol)

    Microsoft Academic Search

    Hironobu Nishino; Ryoji Takahashi; Satoshi Sato; Toshiaki Sodesawa

    2004-01-01

    Silica gel samples with macropores were prepared from solutions of silicate and poly(vinyl alcohol) (PVA), where macropores were formed by fixing a transitional structure of phase separation. Among the silica sources tested, tetraethoxysilane (TEOS), colloidal silica and water glass, only the system with water glass shows phase separation and forms macroporous silica gel. In the system with TEOS, ethanol formed

  1. The Rheological Properties of Poly(Vinyl Alcohol) Gels from Rotational Viscometry

    ERIC Educational Resources Information Center

    Hurst, Glenn A.; Bella, Malika; Salzmann, Christoph G.

    2015-01-01

    A laboratory experiment was developed to follow the gelation of a polyvinyl alcohol (PVA) solution upon addition of borax by using rotational viscometry. The rheological properties of the gel were examined, measuring the dependence of viscosity and shear stress on the shear rate. Time-dependent studies were also conducted in which the viscosity of…

  2. The Effect of High Intensity UV Irradiation on Color Behavior of Poly(Vinyl Chloride)

    Microsoft Academic Search

    Xiaofei Zhang; Hong Pi; Shaoyun Guo

    2012-01-01

    A detailed study of color change in poly(vinyl chloride) (PVC) sheets due to high intensity ultraviolet (UV) irradiation was undertaken, focusing on the first 50 h of change. Color changes were monitored with a Datacolor check spectrophotometer and compared with a set of controls. Measurements were taken after 1, 3, 5, 10, 15, and 20 h of irradiation, then at

  3. Treatment of aquarium water by denitrifying photosynthetic bacteria using immobilized polyvinyl alcohol beads

    Microsoft Academic Search

    Hisashi Nagadomi; Takako Hiromitsu; Kenji Takeno; Masanori Watanabe; Ken Sasaki

    1999-01-01

    During the purification of an aquarium for carp breeding, a relatively high level of chemical oxygen demand (COD) was removed by filtration systems packed with both alginate- and polyvinyl alcohol (PVA)-immobilized gel beads of Rhodobacter sphaeroides S. Low nitrate accumulation was observed in the alginate gel beads packed system due to denitrification, but high levels of nitrate and nitrite accumulation

  4. Characterization of poly(vinyl chloride) aged in a bromine containing electrolyte

    Microsoft Academic Search

    C. Jr. Arnold; A. Leo; M. Tarjani

    1988-01-01

    Poly(vinyl chloride) (PVC) is being considered for use as a flow frame material in a developmental zinc\\/bromine battery. The choice of PVC was based on its low cost and the ease with which it can be molded into complex parts. The electrolyte used in this battery is a highly corrosive mixture of bromine, zinc bromide, zinc chloride, potassium bromide, potassium

  5. Evaluation of an innovative polyvinyl chloride (PVC) ultrafiltration membrane for wastewater treatment

    Microsoft Academic Search

    Xuezhi Zhang; Yongsheng Chen; A. H. Konsowa; Xiaoshan Zhu; John C. Crittenden

    2009-01-01

    The use of ultrafiltration (UF) employing a polyvinyl chloride (PVC) membrane (LH3-1060-V) as pretreatment for a reverse osmosis (RO) system treating secondary water effluent at the Scottsdale Water Campus was investigated. Membrane fouling tendency was evaluated, foulants were characterized, and chemical cleaning was optimized. Feed and permeate water qualities were indexed to address the effect of UF as a pretreatment

  6. Concanavalin A and polyvinyl butyral use as a potential dengue electrochemical biosensor

    Microsoft Academic Search

    Maria D. L. Oliveira; Maria T. S. Correia; Flamarion B. Diniz

    2009-01-01

    Immobilization of concanavalin A on gold electrode by means of gold nanoparticles and polyvinyl butyral was carried out and investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The system was tested with sera from patients infected by dengue fever (DF) and dengue hemorrhagic fever (DHF). Electrochemical impedance spectroscopy (in the frequency range from 100mHz to 100KHz), and cyclic voltammetry (from

  7. Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars

    SciTech Connect

    Abdul-Majid, S.; Othman, F. [King Abdulaziz Univ., Jeddah (Saudi Arabia)

    1994-03-01

    Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples. 34 refs., 16 figs., 4 tabs.

  8. CHARACTERIZATION OF BIODEGRADABLE COMPOSITE FILMS PREPARED FROM BLENDS OF POLYVINYL ALCOHOL, CORNSTARCH AND LIGNOCELLULOSICC FIBER

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Several composite blends of poly(vinyl alcohol) (PVA) and lignocellulosic fibers were prepared and characterized. Cohesive and flexible cast films were obtained by blending lignocellulosic fibers derived from orange waste and PVA with or without cornstarch. Films were evaluated for their thermal s...

  9. Molecular dynamics simulation on surface modification of carbon black with polyvinyl alcohol

    Microsoft Academic Search

    Shijin Dong; Juntao Yan; Nan Xu; Jia Xu; Hongyan Wang

    2011-01-01

    A novel and reasonable model of carbon black (CB) was built to investigate the surface encapsulation modification of CB particles with polyvinyl alcohol (PVA) by molecular dynamic simulation. The modification process of PVA on CB surface was intuitively exhibited, which indicated that the encapsulation films were formed by stacking PVA molecules layer by layer on the surface of CB. The

  10. Polyvinyl Pyrrolidone is not Effective for Improving Recovery of Cryopreserved Shoots of Two Rubus Cultivars

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of the antioxidant polyvinyl pyrrolidone as a pretreatment or recovery treatment for Rubus shoot cultures was tested with two blackberry cultivars. Plantlet growth was initially evaluated on medium with 1 to 10% PVP (10,000 MW). Growth and multiplication of the plantlets was severely inhib...

  11. Efficacy of Trisacryl Gelatin Microspheres versus Polyvinyl Alcohol Particles in the Preoperative Embolization of Meningiomas

    Microsoft Academic Search

    Martin Bendszus; Rudiger Klein; Ralf Burger; Monika Warmuth-Metz; Erich Hofmann; Laszlo Solymosi

    BACKGROUND AND PURPOSE: Trisacryl gelatin microspheres are a new, commercially available nonabsorbable embolic agent. The purpose of this study was to evaluate their efficacy in the preoperative embolization of meningiomas as compared with polyvinyl alcohol (PVA) particles of various sizes. METHODS: In 30 consecutive patients, trisacryl gelatin microspheres (150-300 mm) were used for the preoperative superselective embolization of meningiomas (group

  12. Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

    Microsoft Academic Search

    Patricia Jeanene Willcox

    1998-01-01

    This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine

  13. Poly(vinyl alcohol)–collagen hydrolysate thermoplastic blends: I. Experimental design optimisation and biodegradation behaviour

    Microsoft Academic Search

    P. Alexy; D. Bakoš; S. Hanzelová; L. Kukolíková; J. Kupec; K. Charvátová; E. Chiellini; P. Cinelli

    2003-01-01

    Hybrid blends based on poly(vinyl alcohol) (PVA) and collagen hydrolysate (CH), an abundant, added value waste product of the leather industry, have been processed by melt blow extrusion to environmentally degradable films. Optimisation of the blend compositions was performed in respect of mechanical properties of the films. The experimental design method (DOE) was used for the understanding of the structure–property

  14. FOAMED ARTICLES BASED ON POTATO STARCH, CORN AND WHEAT FIBRE, AND POLY(VINYL ALCOHOL)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Continued research cooperation between USDA Laboratories (USA) and the University of Pisa, Italy, has yielded several composites based on blends of poly(vinyl alcohol) (PVA) and either corn or wheat fibres, co-product of the corn-wheat wet-milling process. Foam trays were prepared by baking the blen...

  15. Poly(vinyl alcohol)\\/Fatty Acid Blends for Thermal Energy Storage

    Microsoft Academic Search

    A. Sari; K. Kaygusuz

    2007-01-01

    This article is aimed to prepare the blends of poly(vinyl alcohol) (PVA) with fatty acids (lauric, myristic, palmitic, and stearic acids) as shape-stabilized phase change material (PCM), to prove the miscibility of fatty acids with the PVA by microscopic investigation and infrared (IR) spectroscopy, and to measure their melting temperature and the latent heat of fusion by differential scanning calorimetry

  16. Oxidative Mineralization and Characterization of Polyvinyl Alcohol Solutions for Wastewater Treatment

    SciTech Connect

    Oji, L.N.

    1999-08-31

    The principal objectives of this study are to identify an appropriate polyvinyl alcohol (PVA) oxidative mineralization technique, perform compatibility and evaporation fate tests for neat and mineralized PVA, and determine potential for PVA chemical interferences which may affect ion exchange utilization for radioactive wastewater processing in the nuclear industry.

  17. Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars.

    PubMed

    Abdul-Majid, S; Othman, F

    1994-03-01

    Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples. PMID:8106253

  18. Mechanism of growth of colloidal silver nanoparticles stabilized by polyvinyl pyrrolidone in ?-irradiated silver nitrate solution

    Microsoft Academic Search

    Hyeon Suk Shin; Hyun Jung Yang; Seung Bin Kim; Mu Sang Lee

    2004-01-01

    Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and ?-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution,

  19. Enhanced Degradation of Polyvinyl Alcohol by Pycnoporus cinnabarinus after Pretreatment with Fenton’s Reagent

    PubMed Central

    Larking, Daniel M.; Crawford, Russell J.; Christie, Gregor B. Y.; Lonergan, Greg T.

    1999-01-01

    Degradation of polyvinyl alcohol (PVA) was investigated by using a combination of chemical treatment with Fenton’s reagent and biological degradation with the white rot fungus Pycnoporus cinnabarinus. Inclusion of the chemical pretreatment resulted in greater degradation of PVA than the degradation observed when biological degradation alone was used. PMID:10103286

  20. Recovery of agricultural odors and odorous compounds from polyvinyl fluoride film bags

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human ...

  1. Comparison of storage stability of odorous VOCs in polyester aluminum and polyvinyl fluoride tedlar bags

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole air sampling using containers such as flexible bags or rigid canisters is commonly used to collect samples of volatile organic compounds (VOC) in air. The objective of this study was to compare the stability of polyester aluminum (PEA) and polyvinyl fluoride (PVF, brand name Tedlar®) bags for ...

  2. The accuracy of three impression transfer techniques for implant supported prostheses.

    PubMed

    Dullabh, H D; Sykes, L M

    2008-09-01

    Cast framework for osseointegrated implant retained prostheses need to be passively fitting so as not to place undue forces and stress concentrations around the fixtures. Impression materials and techniques play a key role in the accuracy and fit of the metal framework. In this study, three impression procedures were investigated to establish which was the most accurate, reliable and predictable. This included using smooth sided tapered transfer copings and unsplinted and splinted square undercut transfer copings. A metal plated master model was fabricated and used as the standard against which models poured using the different impression techniques were compared. Readings were taken with a Reflex Microscope and used to calculate the mean, standard deviation and deviation index for each test model. The results of this study suggest that direct coping transfer techniques provide comparable or better results than indirect coping transfers in master cast fabrication. There was no significant difference in impression transfer accuracy between splinted and non-splinted square impression coping transfer techniques. PMID:19055105

  3. Valence-Based Age Differences in Medial Prefrontal Activity during Impression Formation

    PubMed Central

    Cassidy, Brittany S.; Leshikar, Eric D.; Shih, Joanne Y.; Aizenman, Avigael; Gutchess, Angela H.

    2013-01-01

    Reports of age-related changes to medial prefrontal cortex (mPFC) activity during socio-cognitive tasks have shown both age-equivalence and under recruitment. Emotion work illustrates selective mPFC response dependent on valence, such that negative emotional images evoke increased ventral mPFC activity for younger adults, while older adults recruit ventral mPFC more for positive material. By testing whether this differential age-related response toward valenced material is also present for the social task of forming impressions, we may begin to understand inconsistencies regarding when age differences are present vs. absent in the literature. Using fMRI, participants intentionally formed impressions of positive and negative face-behavior pairs in anticipation of a memory task. Extending previous findings to a social task, valence-based reversals were present in dorsal and ventral mPFC, and posterior cingulate cortex. Younger adults elicited increased activity when forming negative impressions, while older adults had more recruitment when forming positive impressions. This suggests an age-related shift toward emphasizing positive social information may be reflected in the recruitment of regions supporting forming impressions. Overall, the results indicate an age-related shift in neural response to socio-cognitive stimuli that is valence dependent rather than a general age-related reduction in activity, in part informing prior inconsistencies within the literature. PMID:23998453

  4. Reducing job insecurity and increasing performance ratings: does impression management matter?

    PubMed

    Huang, Guo-hua; Zhao, Helen Hailin; Niu, Xiong-ying; Ashford, Susan J; Lee, Cynthia

    2013-09-01

    Prior research on job insecurity has demonstrated its detrimental effects on both employees and the organization, yet no research has detailed how people actively deal with it. Drawing from proactivity research, this article argues that job insecurity prompts a proactive use of impression management tactics in the workplace. The effectiveness of these tactics depends on the level of supervisory liking for the employee and the attributions supervisors make regarding the employee's motives for the impression management behaviors (i.e., for the good of the organization or for self-interest). A 3-wave survey study of 271 Chinese employees and their supervisors showed that employees experiencing job insecurity in Time 1 reported using a variety of tactics to impress their supervisors at Time 2 and that these tactics curbed the affect associated with job insecurity and enhanced supervisor rated performance, through supervisor's liking and attributed motives. The relationship between impression management and increased supervisor-rated performance was moderated by supervisor attributions; the relationship between impression management and reduced affective job insecurity depended on supervisor liking. PMID:23731028

  5. Preparation of electrospun fiber mats using siloxane-containing vaterite and biodegradable polymer hybrids for bone regeneration.

    PubMed

    Fujikura, Kie; Lin, Sen; Nakamura, Jin; Obata, Akiko; Kasuga, Toshihiro

    2013-11-01

    An electrospun fiber mat using a new composite consisting of siloxane-containing vaterite (SiV) and poly(lactic-co-glycolic acid) (PLGA) (denoted by SiPLGVH) was prepared with the aim of applying it as a membrane for use in a guided bone regeneration (GBR) system. Another electrospun fiber mat using a previously described composite consisting of SiV and poly(L-lactic acid) (denoted by SiPVH) was also prepared as a comparative sample. SiPLG VH fiber mats showed superior results in terms of mechanical tensile properties and cellular behavior. Their elongation before failure was about eight times higher than that of SiPVH. The numbers of osteoblast-like cells that proliferated on the SiPLGVH fiber mats, regardless of the hydroxyapatite coating, were comparable to that of SiPVH. The cells spread more, two dimensionally, on the SiPLGVH fiber mats, since the pores between fibers were narrowed down because of swelling of the PLGA matrix during cell culture. This two-dimensional cellular proliferation quality on the SiPLGVH fiber mats is expected to be suitable for materials used in GBR, leading to control of infiltration of the soft tissue and great tissue integration with the surrounding tissue. PMID:23687079

  6. Consistency in trophic magnification factors of cyclic methyl siloxanes in pelagic freshwater food webs leading to brown trout.

    PubMed

    Borgå, Katrine; Fjeld, Eirik; Kierkegaard, Amelie; McLachlan, Michael S

    2013-12-17

    Cyclic volatile methyl siloxanes (cVMS) concentrations were analyzed in the pelagic food web of two Norwegian lakes (Mjøsa, Randsfjorden), and in brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) collected in a reference lake (Femunden), in 2012. Lakes receiving discharge from wastewater treatment plants (Mjøsa and Randsfjorden) had cVMS concentrations in trout that were up to 2 orders of magnitude higher than those in Femunden, where most samples were close to the limit of quantification (LOQ). Food web biomagnification of cVMS in Mjøsa and Randsfjorden was quantified by estimation of trophic magnification factors (TMFs). TMF for legacy persistent organic pollutants (POPs) were analyzed for comparison. Both decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6) biomagnified with TMFs of 2.9 (2.1-4.0) and 2.3 (1.8-3.0), respectively. Octamethylcyclotetrasiloxane (D4) was below the LOQ in the majority of samples and had substantially lower biomagnification than for D5 and D6. The cVMS TMFs did not differ between the lakes, whereas the legacy POP TMFs were higher in Mjøsa than inRandsfjorden. Whitefish had lower cVMS bioaccumulation compared to legacy POPs, and affected the TMF significance for cVMS, but not for POPs. TMFs of D5 and legacy contaminants in Lake Mjøsa were consistent with those previously measured in Mjøsa. PMID:24279694

  7. Compatibilization of polystyrene and poly(dimethyl siloxane) with a star polymer having a ?tcyclodextrin core and polystyrene arms

    NASA Astrophysics Data System (ADS)

    Balik, C. M.; Tonelli, A. E.; Busche, Brad

    2010-03-01

    Cyclodextrins (CDs) are cyclic starch molecules having a hollow central cavity which can be threaded by a polymer to form an inclusion compound. This characteristic is exploited in a new type of compatibilizer: a star polymer with a ?tCD core and polystyrene (PS) arms. Atom transfer radical polymerization is used to grow and control the size of the PS arms from brominated initiator sites on ?tCD. Solutions and thin films of PS and poly(dimethyl siloxane) (PDMS) are compatibilized by this CD-star. The mechanism of compatibilization involves threading of the CD core by PDMS and solubilization of the resulting ``slip-ring graft copolymer'' via the PS star arms. Compatibilization of PS/PDMS in chloroform is visually observed when the initially turbid suspensions become clear solutions after addition of CD-star. Thin films spin-cast from these solutions exhibit a high degree of homogeneity and a nanoscale level of mixing. The solutions are characterized with NMR, dynamic light scattering and intrinsic viscosity measurements, and the thin films are characterized with optical and atomic force microscopy. Many different polymers are capable of threading the CD core, thus the same CD-star molecule could be used to compatibilize several different threading polymers with the same matrix polymer.

  8. Molecular-level insights into the reactivity of siloxane-based electrolytes at a lithium-metal anode.

    PubMed

    Assary, Rajeev S; Lu, Jun; Luo, Xiangyi; Zhang, Xiaoyi; Ren, Yang; Wu, Huiming; Albishri, Hassan M; El-Hady, D Abd; Al-Bogami, A S; Curtiss, Larry A; Amine, Khalil

    2014-07-21

    A molecular-level understanding of the reactions that occur at the lithium-metal anode/electrolyte interphase is essential to improve the performance of Li-O(2) batteries. Experimental and computational techniques are applied to explore the reactivity of tri(ethylene glycol)-substituted trimethylsilane (1NM3), a siloxane-based ether electrolyte, at the lithium-metal anode. In situ/ex situ X-ray diffraction and Fourier-transform infrared spectroscopy studies provide evidence of the formation of lithium hydroxide and lithium carbonates at the anode upon gradual degradation of the metallic lithium anode and the solvent molecules in the presence of oxygen. Density functional calculations performed to obtain a mechanistic understanding of the reductive decomposition of 1NM3 indicate that the decomposition does not require any apparent barrier to produce lithium hydroxide and lithium carbonates when the reduced 1NM3 solvent molecules interact with the oxygen crossing over from the cathode. This study indicates that degradation may be more significant in the case of the 1NM3 solvent, compared to linear ethers such as tetraglyme or dioxalone, because of its relatively high electron affinity. Also, both protection of the lithium metal and prevention of oxygen crossover to the anode are essential for minimizing electrolyte and anode decomposition. PMID:24986260

  9. The orientational order parameters of a dendritic liquid crystal organo-siloxane tetrapode oligomer, determined using polarized infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Merkel, K.; Kocot, A.; Vij, J. K.; Mehl, G. H.; Meyer, T.

    2004-09-01

    The observed macroscopic anisotropic properties such as the components of infrared (IR) absorbances of liquid crystals are expressed in terms of the order parameters of the long molecular axis, molecular, and phase biaxiality. The order parameters of the organo-siloxane tetrapode liquid crystal of zero dendritic order (G0) in its nematic and smectic phases have been determined using results of the polarized IR spectroscopic measurements on a planar homogenously and hometropic aligned cells. The spatial components of the absorbances for the vibrational bands (in the mesogenic unit, terminal chains, and spacer) have been measured and analyzed. For the laboratory reference system, the apparent orientational order parameter S of the mesogen unit shows a significant drop in the transition from the nematic to the smectic phase while the phase biaxiality order parameter P increases to almost 0.4 in the smectic phase. This result shows that the director is tilted out of the sample plane in the smectic phase. The molecular biaxiality parameter D is found to be positive both for the nematic and smectic phases. This suggests that the carbonyl dipoles are oriented close to the tilt plane. For the vibrational bands in the chains, low values of S and D indicative of their low orientational order are obtained. As a result of the interaction among the molecules in the tilted smectic phases, the transition dipoles show positive correlations for the transversal and negative for the longitudinal dipoles.

  10. Determination of poly(dimethyl)siloxane-water partition coefficients for selected hydrophobic organic chemicals using 14C-labeled analogs.

    PubMed

    Yang, Ze-Yu; Greenstein, Darrin; Zeng, Eddy Y; Maruya, Keith A

    2007-04-27

    Aqueous solutions of (14)C-labeled analogs of seven hydrophobic organic chemicals (HOCs) were subject to solid-phase microextraction (SPME) under static conditions to assess their multi-compartment distribution and to compare poly(dimethyl)siloxane (PDMS)-water partition coefficients (K(f) values) with previously reported values. To accomplish this, a protocol for quantitative desorption of radiolabelled HOCs from SPME fibers using hexane was developed. Time series extractions indicated that loading of SPME fibers had reached steady-state by day 8 for PCBs 52, 77 and 153, phenanthrene, benzo[a]pyrene, p,p'-DDT and p,p'-DDE. The recovery of spiked radioactivity among the (residual) aqueous phase, the PDMS coating, and all remaining wetted experimental surfaces ranged between 80 and 120%. K(f) values based on (14)C-labeled analogs were in good agreement with previously published values that were determined at (or closely approaching) equilibrium conditions and without significant chemical depletion and/or uncorrected system losses. Because it allows for the direct determination of HOCs associated with the residual aqueous and experimental surface compartments, the use of radiolabelled HOC analogs is a powerful tool in discriminating among competing sorptive compartments encountered in most SPME fiber calibration methodologies employed to date. PMID:17383665

  11. Combinable poly(dimethyl siloxane) capillary sensor array for single-step and multiple enzyme inhibitor assays.

    PubMed

    Uchiyama, Yosuke; Okubo, Fumito; Akai, Kozo; Fujii, Yuji; Henares, Terence G; Kawamura, Kunio; Yao, Toshio; Endo, Tatsuro; Hisamoto, Hideaki

    2012-01-01

    We describe a new method for fabricating a capillary-type sensor, called a combinable poly(dimethyl siloxane) (PDMS) capillary (CPC) sensor. The method for preparing the CPC simplifies enzyme inhibitor assays into a simple, single step assay. The sample inhibitor solution is introduced by capillary action. This triggers the spontaneous dissolution of physically adsorbed fluorescent substrates, and the substrate mixes with the inhibitor. This is followed by competitive reaction with insoluble enzyme to give a fluorescence response. CPC is composed of a convex-shaped PDMS stick containing reagents immobilized in an insoluble coating, and a concave-shaped PDMS stick containing reagents immobilized in a soluble coating. Since the concave-shaped PDMS has a deeper channel than the convex structure, combining these PDMS sticks is like closing the zipper of a "freezer bag". This allows easy fabrication of "thin and long" capillary structures containing different reagents inside the same capillary, without the need for precise alignment. This method allows the immobilization of two reactive reagents, such as enzyme and substrate required for a single step assay, which are typically very difficult to immobilize using commercially available conventional capillaries. Furthermore, by simply arraying various CPCs, the CPC sensor allows multiple assays. Here, we carried out a single-step enzyme inhibitor assay using the CPC. In addition, two independent CPCs were arrayed to demonstrate multiple assaying of a protease inhibitor. PMID:22086459

  12. Rapid prototyping of microfluidic switches in poly(dimethyl siloxane) and their actuation by electro-osmotic flow

    NASA Astrophysics Data System (ADS)

    Duffy, David C.; Schueller, Olivier J. A.; Brittain, Scott T.; Whitesides, George M.

    1999-09-01

    This paper describes a procedure for rapidly and conveniently prototyping microfluidic devices that are useful with aqueous solutions. A design (with diameters of channels icons/Journals/Common/ge" ALT="ge" ALIGN="TOP"/>20 µm) is created in a computer-aided design program and printed at high resolution on a transparency. This transparency is used as a mask in photolithography to create a master in positive relief photoresist: casting poly(dimethyl siloxane) (PDMS) against this master yields a polymeric replica containing a network of bas-relief channels. The channels are closed and sealed irreversibly by oxidizing the replica and another flat substrate (PDMS, glass, silicon, silicon oxide) in an oxygen plasma and bringing the two surfaces into conformal contact. Oxidation of the polymer allows the formation of a seal without using adhesives; it also generates channels that support electro-osmotic flow (EOF) and fill easily with aqueous solutions. Two microfluidic devices - a fluidic switch and a side channel flow controller - have been fabricated using this rapid prototyping methodology. These devices were tested using aqueous solutions as the test fluid and actuated by EOF.

  13. Sensitivity of Perianal Tape Impressions to Diagnose Pinworm (Syphacia spp.) Infections in Rats (Rattus norvegicus) and Mice (Mus musculus)

    PubMed Central

    Hill, William Allen; Randolph, Mildred M; Mandrell, Timothy D

    2009-01-01

    We determined the sensitivity of perianal tape impressions to detect Syphacia spp. in rats and mice. We evaluated 300 rat and 200 mouse perianal impressions over 9 wk. Pinworm-positive perianal tape impressions from animals with worm burdens at necropsy were considered as true positives. Conversely, pinworm-negative perianal tape impressions from animals with worm burdens were considered false negatives. The sensitivity of perianal tape impressions for detecting Syphacia muris infections in rats was 100%, and for detecting Syphacia obvelata in mice was 85.5%. Intermittent shedding of Syphacia obvelata ova is the most probable explanation for the decreased sensitivity rate we observed in mice. We urge caution in use of perianal tape impressions alone for Syphacia spp. screening in sentinel mice and rats. PMID:19653945

  14. Applicable research in practice: understanding the hydrophilic and flow property measurements of impression materials.

    PubMed

    Perry, Ronald D; Goldberg, Jeffrey A; Benchimol, Jacques; Orfanidis, John

    2006-10-01

    The flow properties and hydrophilicity of an impression material are key factors that affect its performance. This article details in vitro studies comparing these properties in 1 polyether and several vinyl polysiloxane light-body impression materials. The first series of studies examined the materials' flow properties used in a "shark fin" measurement procedure to determine which exhibited superior flow characteristics. The second series of studies reviewed the hydrophilic properties of the materials. Video analysis was used to record contact angle measurements at the early- and late-stage working times. Results showed 1 polyether material to be more hydrophilic. Applying this knowledge to practice, the authors present a clinical case in which a polyether's superior flow and quality of detail were used to make impressions for a patient receiving 8 single-unit zirconia crowns. PMID:17120392

  15. Silicone impression material foreign body in the middle ear: Two case reports and literature review.

    PubMed

    Suzuki, Nobuyoshi; Okamura, Koji; Yano, Takuya; Moteki, Hideaki; Kitoh, Ryosuke; Takumi, Yutaka; Usami, Shin-Ichi

    2015-10-01

    We report two cases of impression material foreign body in the middle ear. The first case had been affected with chronic otitis media. The silicone flowed into the middle ear through a tympanic membrane perforation during the process of making an ear mold. About 4 years and 8 months after, the patient had severe vertigo and deafness. We found bone erosion of the prominence of the lateral semicircular canal and diagnosed labyrinthitis caused by silicone impression material. In the second case silicone flowed into the canal wall down mastoid cavity. Both cases required surgery to remove the foreign body. The clinical courses in such cases are variable and timing of surgery is sometimes difficult. In addition to reporting these two cases, we present here a review of the literature regarding impression material foreign bodies. PMID:25956272

  16. Influence of impression of vehicle styling on loudness of acceleration sounds in cabin.

    PubMed

    Yoshida, Junji; Igata, Takumi

    2011-07-01

    The influence of participants' impressions of vehicle styling on the loudness of acceleration sounds was investigated. A series of images of luxury or sporty vehicles was presented to the participants as acceleration sounds were being replayed. The results indicated that participants who were frequent drivers felt that the sound associated with luxury vehicles was louder than that associated with sporty vehicles. However, participants who rarely drove perceived almost no difference between the loudness of the two vehicles types. Thus, the loudness was shown to depend on both the participants' impression of the vehicle and their driving frequency. PMID:21786863

  17. Discoidal impressions and trace-like fossils more than 1200 million years old.

    PubMed

    Rasmussen, Birger; Bengtson, Stefan; Fletcher, Ian R; McNaughton, Neal J

    2002-05-10

    The Stirling Range Formation of southwestern Australia contains discoidal impressions and trace-like fossils in tidal sandstones. The various disks have previously been linked to the Ediacaran biota, younger than 600 million years old. From this unit, we report U-Th-Pb geochronology of detrital zircon and monazite, as well as low-grade metamorphic monazite, constraining the depositional age to between 2016 +/- 6 and 1215 +/- 20 million years old. Although nonbiological origins for the discoidal impressions cannot be completely discounted, the structures resembling trace fossils clearly have a biological origin and suggest the presence of vermiform, mucus-producing, motile organisms. PMID:12004128

  18. Sorption of boric acid by hydroxylic sorbents synthesized from polyvinyl alcohol and polyvinylene glycol

    SciTech Connect

    Kisel'gof, G.V.; Arkhangel'skii, L.K.; Bochkova, N.A.

    1986-10-10

    It has been shown that sorbents synthesized from polyvinyl alcohol (PVA) and polyvinyl glycol (PVG) are the most effective agents for extraction of boron from natural waters and brines. The action of such sorbents is based on the ability of boric acid to form stable complexes with polyhydroxy compounds. In this work the authors studied hydroxylic sorbents differing in OH-group contents and in the amounts and nature of the cross-linking agent. The principal characteristics of the sorbents studied are given. The theoretical capacity was calculated on the assumption that the structural unit sorbing one boric acid molecule is -CH/sub 2/-CHOH-CH/sub 2/CHOH- in PVA and -CHOH-CHOH- in PVG.

  19. Leaching of diethylhexyl phthalate from polyvinyl chloride bags into intravenous cyclosporine solution

    SciTech Connect

    Venkataramanan, R.; Burckart, G.J.; Ptachcinski, R.J.; Blaha, R.; Logue, L.W.; Bahnson, A.; Giam, C.S.; Brady, J.E.

    1986-11-01

    The release of diethylhexyl phthalate (DEHP) from flexible polyvinyl chloride containers into intravenous cyclosporine solutions was studied. Intravenous cyclosporine solution or solutions containing the vehicle Cremophor EL and alcohol in dextrose were prepared in an all-glass system and stored in polyvinyl chloride (PVC) bags. Four samples were obtained at different time intervals, and DEHP content was analyzed by gas chromatography. The amount of DEHP that was leached into solutions stored in the PVC bags increased as storage time increased. By 48 hours, nearly 33 mg of DEHP had leached into the solution. Intravenous cyclosporine solutions should be prepared in glass containers to minimize patient exposure to DEHP. If plastic bags are used for preparing cyclosporine injections, the injections must be used immediately after preparation.

  20. Polyvinyl alcohol-coated hybrid fiber grating for relative humidity sensing

    NASA Astrophysics Data System (ADS)

    Dong, Xinyong; Li, Tao; Liu, Yang; Li, Yi; Zhao, Chun-Liu; Chan, Chi Chiu

    2011-07-01

    A relative humidity (RH) sensor based on a hybrid fiber grating coated with polyvinyl alcohol is proposed and demonstrated experimentally. The hybrid fiber grating is formed by superimposing a normal fiber Bragg grating (FBG) and a tilted-FBG around the same position of a single-mode fiber so that it can work in the reflection mode. Optical power of the reflected signal changes with the refractive index of the moisture sensitive polyvinyl alcohol, and humidity measurement can be realized. Experimental results show that the measurement range is 30 to 95% with the maximum sensitivity of 0.737 nW/% RH. The average response time is ~2 s and the measurement is nearly insensitive to temperature. Compared with the wavelength detection method used in normal FBG-based relative humidity sensors, the intensity demodulation method in this report is simpler and more cost-efficient.

  1. Characterization of poly(vinyl acetate)\\/sugar cane bagasse lignin blends and their photochemical degradation

    Microsoft Academic Search

    M. F. Silva; E. A. G. Pineda; A. A. W. Hechenleitner; D. M. Fernandes; M. K. Lima; P. R. S. Bittencourt

    The acetone-soluble lignin fraction (ASLF) of sugar cane bagasse, from a sugar and alcohol factory residue, was obtained after\\u000a extraction with formic acid and used to prepare blends with poly(vinyl acetate) (PVAc) by casting. PVAc and ASLF\\/PVAc blends\\u000a were irradiated with ultraviolet light (Hg lamp). Blend formation and the irradiation effects were examined through thermal\\u000a analysis (TG and DSC), scanning

  2. Effect of crosslinking on the mechanical and thermal properties of poly(vinyl alcohol)

    Microsoft Academic Search

    M Krumova; D López; R Benavente; C Mijangos; J. M Pereña

    2000-01-01

    Poly(vinyl alcohol) was crosslinked with hexamethylene diisocyanate in solution. A broad range of degrees of crosslinking, from 1.7 up to 74mol% of reacted hydroxyl groups, was achieved. The variation of the thermal and mechanical properties of PVA with the crosslinking density show an initial decrease due to the diminution of the crystallinity of the system, caused by the crosslinking. After

  3. Electrical, mechanical and thermal properties of polyvinyl chloride composites filled with aluminum powder

    Microsoft Academic Search

    I. K. Bishay; S. L. Abd-El-Messieh; S. H. Mansour

    2011-01-01

    In this work, the electrical, mechanical and thermal properties of polyvinyl chloride (PVC) composites filled with different content of aluminum powder varying from 0 to 40wt.% have been prepared. The dielectric properties of these composites were investigated in the frequency range 100Hz–100kHz at temperature range from 30 to 98°C. The percolation threshold concentration, which is the concentration after which the

  4. Effects of molecular weight and stereoregularity on biodegradation of poly(vinyl alcohol) by Alcaligenes faecalis

    Microsoft Academic Search

    Shuichi Matsumura; Yukimasa Shimura; Koutaro Terayama; Takato Kiyohara

    1994-01-01

    Summary The biodegradability of poly(vinyl alcohol) (PVA) was analyzed with respect to its molecular weight and stereoregularity using the isolated PVA-assimilating microbial strain,Alcaligenes faecalis KK314. The biodegradability of PVA was influenced by its stereoregularity, and the isotactic moiety was preferentially biodegraded. However, there is no difference in the biodegradability based on the molecular weight of PVA being larger than the

  5. Electrospun single-walled carbon nanotube\\/polyvinyl alcohol composite nanofibers: structure property relationships

    Microsoft Academic Search

    Minoo Naebe; Tong Lin; Mark P. Staiger; Liming Dai; Xungai Wang

    2008-01-01

    Polyvinyl alcohol (PVA) nanofibers and single-walled carbon nanotube (SWNT)\\/PVA composite nanofibers have been produced by electrospinning. An apparent increase in the PVA crystallinity with a concomitant change in its main crystalline phase and a reduction in the crystalline domain size were observed in the SWNT\\/PVA composite nanofibers, indicating the occurrence of a SWNT-induced nucleation crystallization of the PVA phase. Both

  6. Preparation and conductivity of polyvinyl alcohol (PVA) films composited with molybdotungstovanadogermanic heteropoly acid

    Microsoft Academic Search

    Yanli Cui; Jianwei Mao; Qingyin Wu

    2004-01-01

    In this work, the polyvinyl alcohol (PVA) films composited with molybdotungstovanadogermanic heteropoly acid were prepared. Infrared spectra (IR) revealed that the Keggin structure characteristic of the GeMo2W9VO405? anion was present in PVA films. At room temperature (20°C), the conductivity of the samples of different HPA content increased from 2.46×10?3 to 9.92×10?3Scm?1. The results indicated that they are new kind of

  7. Multifunctional baicalein blended poly(vinyl alcohol) composite nanofibers via electrospinning

    Microsoft Academic Search

    R. Nirmala; D. Kalpana; Jin Won Jeong; Hyun Ju Oh; Ji-Hui Lee; R. Navamathavan; Yang Soo Lee; Hak Yong Kim

    2011-01-01

    We report on the preparation and characterizations of multifunctional baicalein blended poly(vinyl alcohol) (PVA) composite nanofibers via electrospinning process. In order to improve the biocompatibility properties, baicalein was blended in to PVA to prepare composite nanofibers. The morphology, structure and thermal properties of the PVA\\/baicalein composite nanofibers were analyzed by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared

  8. Bioartificial materials based on blends of dextran and poly(vinyl alcohol- co-acrylic acid)

    Microsoft Academic Search

    N. Barbani; F. Bertoni; G. Ciardelli; C. Cristallini; D. Silvestri; M. L. Coluccio; P. Giusti

    2005-01-01

    Bioartificial polymeric materials based on blends of dextran and poly(vinyl alcohol-co-acrylic acid) P(VA-co-AA) were prepared in the form of films and characterised to evaluate the miscibility of the natural component with the synthetic one. The idea of this work was to compatibilise PVA and dextran by introducing carboxylic groups along the PVA chains.The copolymer was synthesised and characterised in our

  9. Synthesis and Characterization of Poly(vinyl alcohol) Membranes with Quaternary Ammonium Groups for Wound Dressing

    Microsoft Academic Search

    Kuo-Yu Chen; Yu-Sheng Lin; Chun-Hsu Yao; Ming-Hsien Li; Jui-Che Lin

    2010-01-01

    2-[(acryloyloxy)ethyl]Trimethylammonium chloride (AETMAC) was grafted onto poly(vinyl alcohol) (PVA) using ceric ammonium nitrate (CAN) as a redox initiator. A series of graft co-polymer (PVA-g-PAETMAC) membranes with different contents of AETMAC were prepared with a casting method. The incorporation of AETMAC into PVA chains was confirmed by element analysis and Fourier transform infrared spectroscopy. The effects of grafting on the thermal

  10. Reinforcement and toughening of poly(vinyl chloride) with poly(caprolactone) grafted carbon nanotubes

    Microsoft Academic Search

    Wang Guojiann; Wang Lijuan; Zu Mei; Chang Zhengmian

    2009-01-01

    Poly caprolactone (PCL) was used to modify multiwall carbon nanotubes (MWNTs). The characterization results of TEM, FTIR, Raman, TG and 721 Spectrophotometer showed that PCL was covalently combined with MWNTs. The MWNTs\\/PVC composites were prepared by the addition of pristine and modified MWNTs into poly(vinyl chloride) through melting process. The addition of MWNT-PCL (0.28vol%) increased the Young’s modulus, tensile strength,

  11. Poly(?-caprolactone)-based ‘green’ plasticizers for poly(vinyl choride)

    Microsoft Academic Search

    Guixin Shi; David G. Cooper; Milan Maric

    2011-01-01

    A series of proposed plasticizers for poly(vinyl chloride) (PVC), based on poly(?-caprolactone) (PCL) with octanoate and benzoate-terminal groups, were synthesized with various microstructures and molecular weights (MW) and tested for biodegradability as well as for mechanical performance, and leaching resistance in blends with PVC. The plasticization efficiency of each was characterized by measuring the glass transition temperature (Tg) and tensile

  12. Photochemical stability of poly(vinyl alcohol) in the presence of collagen

    Microsoft Academic Search

    Alina Sionkowska; Anna P?anecka; Justyna Koz?owska; Joanna Skopi?ska-Wi?niewska

    2009-01-01

    The photochemical stability of poly(vinyl alcohol) (PVA) in the presence of 1%, 3% and 5% of collagen has been studied by Fourier Transform Infrared (FTIR) Spectroscopy, UV–vis spectroscopy, and Differential Scanning Calorimetry (DSC). PVA samples containing 1%, 3% and 5% of collagen were irradiated with UV light wavelength ? = 254 nm in air.The results have shown that PVA in the presence of

  13. Changes in the optical spectra of poly(vinyl chloride) as a result of gamma irradiation

    Microsoft Academic Search

    N. A. El-Zaher; W. G. Osiris

    1997-01-01

    In the present work, the effect of different doses of gamma rays ranging from 50 to 500 kGy on the transmission spectra and the tristimulus transmittance as well as the absorption coefficient in the range 400-700 nm of poly(vinyl chloride) (PVC) were studied by the optical transmission spectra. Variation in the group coordination in the near infrared region (700-3000 nm)

  14. Changes in the optical spectra of poly(vinyl chloride) as a result of gamma irradiation

    Microsoft Academic Search

    N. A. El-Zaher; W. G. Osiris

    1997-01-01

    In the present work, the effect of different doses of gamma rays ranging from 50 to 500 kGy on the transmission spectra and the tristimulus transmittance as well as the absorption coefficient in the range 400–700 nm of poly(vinyl chloride) (PVC) were studied by the optical transmission spectra. Variation in the group coordination in the near infrared region (700–3000 nm)

  15. Study on dechlorination technology for municipal waste plastics containing polyvinyl chloride and polyethylene terephthalate

    Microsoft Academic Search

    Masaaki Fukushima; Beili Wu; Hidetoshi Ibe; Keiji Wakai; Eiichi Sugiyama; Hironobu Abe; Kiyohiko Kitagawa; Shigenori Tsuruga; Katsumi Shimura; Eiichi Ono

    2010-01-01

    It is necessary to remove chlorine efficiently from municipal waste plastics (MWP) that contain polyvinyl chloride (PVC) and\\u000a other plastics containing chlorine. In this article we consider thermal degradation liquefaction technology. In Japan, the\\u000a chlorine content of reclamation oil products must be kept below 100 ppm owing to the quality standard for pyrolysis oil. Liquefaction\\u000a dechlorination technology for MWP is

  16. Metal lanolin fatty acid as novel thermal stabilizers for rigid poly(vinyl chloride)

    Microsoft Academic Search

    Yong GUO; Yuying ZHENG; Shangchang QIU; Anran ZENG; Baoming LI

    2011-01-01

    The synergistic stabilization effect of different metal lanolin fatty acids as natural-based thermal stabilizers for poly(vinyl chloride) (PVC) including calcium lanolin fatty acid (Calan2), zinc lanolin fatty acid (Znlan2) and lanthanum lanolin fatty acid (Lalan3) were studied through Congo red testing, color measurements, FTIR analyses and thermal behavior in this paper. The results showed that Lalan3\\/Calan2\\/Znlan2 stabilizers exhibited more excellent

  17. Removal of nitrogen in wastewater by polyvinyl alcohol (PVA)immobilization of effective microorganisms

    Microsoft Academic Search

    Jintae Lee; Moo Hwan Cho

    2010-01-01

    To remove nitrogen and carbon simultaneously from municipal wastewater, a mixture of effective microorganisms (EM) was immobilized\\u000a in polyvinyl alcohol (PVA) hydrogel beads. The modified PVA beads with calcium alginate show characteristic pores and mechanical\\u000a stability and flexibility. The EM-immobilized PVA system was established in a 3 L sequential batch reactor (SBR) with a synthetic\\u000a wastewater and operated at an

  18. Poly(vinyl alcohol) multilayer mixed matrix membranes for the dehydration of ethanol–water mixture

    Microsoft Academic Search

    Huai-Min Guan; Tai-Shung Chung; Zhen Huang; Mei Lin Chng; Santi Kulprathipanja

    2006-01-01

    We have developed multilayer mixed matrix membranes (MMMMs) consisting of a selective mixed matrix membrane (MMM) top layer, a porous poly(acrylonitrile-co-methyl acrylate) [poly(AN-co-MA)] intermediate layer and a polyphenylene sulfide (PPS) nonwoven fabrics substrate. The selective MMM layer was formed by incorporating KA zeolite in poly(vinyl alcohol) (PVA) matrix followed by the cross-linking reaction of PVA with fumaric acid. The fumaric

  19. Photochemical and thermal behaviours of poly(vinyl alcohol)\\/graphite oxide composites

    Microsoft Academic Search

    Halina Kaczmarek; Andrzej Podgórski

    2007-01-01

    The properties of poly(vinyl alcohol)\\/graphite oxide (PVAL\\/GO) composites were investigated during UV irradiation using a mercury lamp (?=254nm). The course of photochemical reactions was monitored by FTIR and UV–vis absorption spectroscopies as well as by estimation of insoluble gel amount formed during crosslinking. Changes in average molecular weights resulting from main chain scission in PVAL were measured by gel permeation

  20. Dielectric properties of montmorillonite clay filled poly(vinyl alcohol)\\/poly(ethylene oxide) blend nanocomposites

    Microsoft Academic Search

    R. J. Sengwa; Shobhna Choudhary; Sonu Sankhla

    2010-01-01

    Organic–inorganic nanocomposites of poly(vinyl alcohol) (PVA)–poly(ethylene oxide) (PEO) blend filled with montmorillonite (MMT) nanoclay up to 10wt.% concentration were synthesized by aqueous solution-cast technique. The complex dielectric function, electrical conductivity, electric modulus and impedance spectra of the nanocomposites were measured in the frequency range 20Hz–1MHz at ambient temperature. A direct correlation was observed between the real part of dielectric function

  1. Rheological properties of polymethyl methacrylate and polyvinyl acetate in the molten state

    Microsoft Academic Search

    Shigeharu Onogi; Toshiro Masuda; Toshio Ibaragi

    1968-01-01

    Summary Dynamic viscosity?', dynamic rigidityG' and apparent viscosity?a of fractions and blends of polymethyl methacrylate and of polyvinyl acetate having different molecular weight and distribution have been measured at high temperatures by means of a concentric cylinder-type rheometer which enables us to measure not only dynamic but also steady-flow properties. The values of?' andG' as functions of frequency for each

  2. Compressibility and compactibility of powdered polymers: poly(vinyl chloride) powders

    Microsoft Academic Search

    Anne-France Rime; Danielle Massuelle; Frank Kubel; Hans-Rudolf Hagemann; Eric Doelker

    1997-01-01

    The present investigation is concerned with the possible effects of material-related properties (molecular mass, glass transition and melting temperatures, crystallinity, tacticity) and particle-related properties (shape, size, specific surface area) on the compression characteristics of the chosen model polymer powder: poly(vinyl chloride) (PVC). Four grades were selected known in literature for providing compacts of varied mechanical strength. The compression characteristics were

  3. Knoevenagel condensation catalysed by poly(vinyl chloride) supported tetraethylenepentamine (PVC-TEPA)

    Microsoft Academic Search

    Fen Dong; Yi Qun Li; Rong Feng Dai

    2007-01-01

    Poly(vinyl chloride) supported tetraethylenepentamine (PVC-TEPA) has been found to be an efficient catalyst for the Knoevenagel condensation. A wide range of aromatic aldehydes easily undergo condensations with ethyl cyanoacetate and malononitrile in the commercial 95% ethanol in refluxing using PVC-TEPA as catalyst to afford the desired products of good purity in moderate to excellent yields. A recycling study confirmed that

  4. Chemically modified fly ash for fabricating super-strong biodegradable poly(vinyl alcohol) composite films

    Microsoft Academic Search

    Dilip Chandra Deb Nath; Sri Bandyopadhyay; Philip Boughton; Aibing Yu; Darryl Blackburn; Chris White

    2010-01-01

    Composite films of poly(vinyl alcohol) (PVA) and chemically modified fly ash (MFA) by sodium hydroxide were prepared by aqueous\\u000a cast method with 5, 10, 15, 20 and 25 wt% MFA treated with 1 wt% cross-linking agent (glutaraldehyde, GLA). The tensile strengths\\u000a of the composite films were found to increase proportionally with MFA and the maximum strength attained was 414% higher in\\u000a the

  5. Nitrification using polyvinyl alcohol-immobilized nitrifying biofilm on an O 2 enriching membrane

    Microsoft Academic Search

    Yuan-Lynn Hsieh; Szu-Kung Tseng; Yu-Jie Chang

    2002-01-01

    A combination of cell immobilization and membrane aeration approaches was used in a biological reactor to treat NH4+ in wastewater. Nitrifying microorganisms, immobilized by polyvinyl-alcohol (PVA) and attached to the surface of a silicone membrane tube, were used to develop a novel reactor for nitrification. The immobilized biofilm had a rubber-like elasticity and resisted shear stress over 5 months of

  6. Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)

    PubMed Central

    Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

    2012-01-01

    Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 ? cm2 and 0.83, respectively. PMID:24958543

  7. Evaluation of CO2-philicity of poly(vinyl acetate) and poly(vinyl acetate-alt-maleate) copolymers through molecular modeling and dissolution behavior measurement.

    PubMed

    Hu, Dongdong; Sun, Shaojun; Yuan, Peiqing; Zhao, Ling; Liu, Tao

    2015-02-19

    Multiscale molecular modeling and dissolution behavior measurement were both used to evaluate the factors conclusive on the CO2-philicity of poly(vinyl acetate) (PVAc) homopolymer and poly(vinyl acetate-alt-maleate) copolymers. The ab initio calculated interaction energies of the candidate CO2-philic molecule models with CO2, including vinyl acetate dimer (VAc), dimethyl maleate (DMM), diethyl maleate (DEM), and dibutyl maleate (DBM), showed that VAc was the most CO2-philc segment. However, the cohesive energy density, solubility parameter, Flory-Huggins parameter, and radial distribution functions calculated by using the molecular dynamics simulations for the four polymer and polymer-CO2 systems indicated that poly(VAc-alt-DBM) had the most CO2-philicity. The corresponding polymers were synthesized by using free radical polymerization. The measurement of cloud point pressures of the four polymers in CO2 also demonstrated that poly(VAc-alt-DBM) had the most CO2-philicity. Although copolymerization of maleate, such as DEM or DBM, with PVAc reduced the polymer-CO2 interactions, the weakened polymer-polymer interaction increased the CO2-philicity of the copolymers. The polymer-polymer interaction had a significant influence on the CO2-philicity of the polymer. Reduction of the polymer-polymer interaction might be a promising strategy to prepare the high CO2-philic polymers on the premise that the strong polymer-CO2 interaction could be maintained. PMID:25599262

  8. Poly(vinyl alcohol) gels for use as tissue phantoms in photoacoustic mammography.

    PubMed

    Kharine, Alexei; Manohar, Srirang; Seeton, Rosalyn; Kolkman, Roy G M; Bolt, René A; Steenbergen, Wiendelt; de Mul, Frits F M

    2003-02-01

    Materials for solid photoacoustic breast phantoms, based on poly(vinyl alcohol) hydrogels, are presented. Phantoms intended for use in photoacoustics must possess both optical and acoustic properties of tissue. To realize the optical properties of tissue, one approach was to optimize the number of freezing and thawing cycles of aqueous poly(vinyl alcohol) solutions, a procedure which increases the turbidity of the gel while rigidifying it. The second approach concentrated on forming a clear matrix of the rigid poly(vinyl alcohol) gel without any scattering, so that appropriate amounts of optical scatterers could be added at the time of formation, to tune the optical properties as per requirement. The relevant optical and acoustic properties of such samples were measured to be close to the average properties of human breast tissue. Tumour simulating gel samples of suitable absorption coefficient were created by adding appropriate quantities of dye at the time of formation; the samples were then cut into spheres. A breast phantom embedded with such 'tumours' was developed for studying the applicability of photoacoustics in mammography. PMID:12608612

  9. Impression de l'emploi du temps Nous ne publions plus les emplois du temps au format PDF. Les temps de publication tant trop long (8h sur 3 serveurs). Il est nanmoins possible d'obtenir une impression

    E-print Network

    Grigoras, .Romulus

    Impression de l'emploi du temps Nous ne publions plus les emplois du temps au format PDF. Les temps firefox Windows Sur le site edt.enseeiht.fr, choisissez votre emploi du temps, soit en totalité soit la fois quelque part dans la grille de l'emploi du temps Demander une impression ("CTRL + P") dans zone d

  10. Studies on silicon NMR characterization and kinetic modeling of the structural evolution of siloxane-based materials and their applications in drug delivery and adsorption

    NASA Astrophysics Data System (ADS)

    Ambati, Jyothirmai

    This dissertation presents studies of the synthetic processes and applications of siloxane-based materials. Kinetic investigations of bridged organoalkoxysilanes that are precursors to organic-inorganic hybrid polysilsesquioxanes are a primary focus. Quick gelation despite extensive cyclization is found during the polymerization of bridged silane precursors except for silanes with certain short bridges. This work is an attempt to characterize and understand some of the distinct features of bridged silanes using experimental characterization, kinetic modeling and simulation. In addition to this, the dissertation shows how the properties of siloxane-materials can be engineered for drug delivery and adsorption. The phase behavior of polymerizing mixtures is first investigated to identify the solutions that favor kinetic characterization. Microphase separation is found to cause gradual loss of NMR signal for certain initial compositions. Distortionless Enhancement by Polarization Transfer 29Si NMR is employed to identify the products of polymerization of some short-bridged silanes under no signal loss conditions. This technique requires knowing indirect 29Si-1H scalar coupling constants which sometimes cannot be measured due to second-order effects. However, the B3LYP density functional method with 6-31G basis set is found to predict accurate 29Si- 1H coupling constants of organoalkoxysilanes and siloxanes. The scalar coupling constants thus estimated are employed to resolve non-trivial coupled NMR spectra and quantitative kinetic modeling is performed using the DEPT Si NMR transients. In order to investigate the role of the organic bridging group, the structural evolution of bridged and non-bridged silanes are compared using Monte Carlo simulations. Kinetic and simulation models suggest that cyclization plays a key role right from the onset of polymerization for bridged silanes even more than in non-bridged silanes. The simulations indicate that the carbosiloxane rings formed from short-bridged precursors slow down but do not prevent gelation. The tuning of siloxane-based materials for adsorption technologies are also discussed here. In the first example, antioxidant enzyme loading is investigated as a means to reduce oxidative stress generated by silica nanoparticle drug carriers. Materials are engineered for promising enzyme loading and protection from proteolysis. Second, the potential of copper sulfate impregnation to enhance adsorption of ammonia by silica is explored by molecular simulation. KEYWORDS: Sol-gel Polymerization, Kinetic Investigation, Si NMR, Bridged Silanes, DFT Calculations.

  11. Boron-Catalyzed Regioselective Deoxygenation of Terminal 1,2-Diols to 2-Alkanols Enabled by the Strategic Formation of a Cyclic Siloxane Intermediate.

    PubMed

    Drosos, Nikolaos; Morandi, Bill

    2015-07-20

    The selective deoxygenation of polyols is a frontier in our ability to harness the stereochemical and structural complexity of natural and synthetic feedstocks. Herein, we describe a highly active and selective boron-based catalytic system for the selective deoxygenation of terminal 1,2-diols at the primary position, a process that is enabled by the transient formation of a cyclic siloxane. The method provides an ideal complement to well-known catalytic asymmetric reactions to prepare synthetically challenging chiral 2-alkanols in nearly perfect enantiomeric excess, as illustrated in a short synthesis of the anti-inflammatory drug (R)-lisofylline. PMID:26089307

  12. You Are Known by How You Vlog: Personality Impressions and Nonverbal Behavior in YouTube

    E-print Network

    Gatica-Perez, Daniel

    You Are Known by How You Vlog: Personality Impressions and Nonverbal Behavior in YouTube Joan in understanding human percep- tion in social media has led to the study of the pro- cesses of personality self and interpersonal perception. We investi- gate the use of nonverbal cues as descriptors of vlog- gers' behavior

  13. 79Black Holes -Hot Stuff! Artist's impression of gas falling into a black hole

    E-print Network

    79Black Holes - Hot Stuff! Artist's impression of gas falling into a black hole Image credit: NASA / Dana Berry, SkyWorks Digital When gas flows into a black hole, it gets very hot and emits light. The gas is heated because the atoms collide with each other as they fall into the black hole. Far away

  14. Integrated Modular Propulsion and Regenerative Electro-energy Storage System (IMPRESS) for small satellites

    Microsoft Academic Search

    F. Mitlitsky; W. de Groot; L. Butler; J. McElroy

    1996-01-01

    The IMPRESS is a significant advancement in space system technology as it is able to operate alternately as a fuel cell to produce electrical power from stored hydrogen and oxygen and as a water electrolyzer using electrical power to produce hydrogen and oxygen from stored water. The electrolysis of a controllable fraction of stored water can provide high Isp rocket

  15. An Exploratory Investigation Examining Male and Female Students' Initial Impressions and Expectancies of Lecturers

    ERIC Educational Resources Information Center

    Batten, John; Birch, Phil David John; Wright, James; Manley, Andrew John; Smith, Matt Jeffrey

    2014-01-01

    The aim of this study was to examine the informational cues that male and female students perceive to be influential when developing initial impressions and expectancies of a lecturer. University students ("n" = 752) rated the extent to which 30 informational cues influence their initial perceptions of a lecturer. Following exploratory…

  16. The Influence of Physical Attractiveness and Dress on Campus Recruiters' Impressions of Female Job Applicants.

    ERIC Educational Resources Information Center

    Johnson, Kim K. P.; Roach-Higgins, Mary E.

    1987-01-01

    The influence of physical attractiveness, dress, and job type upon 300 college recruiters' impressions of females' employment potential was investigated. Subjects rated female applicants from a photograph on eight employment potential statements. Results indicate that the applicant's style of dress exerted a consistent influence on recruiters'…

  17. RAW: conveying minimally-mediated impressions of everyday life with an audio-photographic tool

    Microsoft Academic Search

    Joëlle Bitton; Stefan Agamanolis; Matthew Karau

    2004-01-01

    This paper traces the development of RAW, a system combining a tool and a process for capturing and conveying audiovisual impressions of everyday life. The project aims to enable a relationship between the user of the tool and an audience in a different place or time with an absolute minimum of editorial mediation by a third party. The tool itself

  18. OfficeMax ImPress is your printing services resource.

    E-print Network

    OfficeMax ImPress is your printing services resource. Whatever your printing needs, we can do it and printing services from OfficeMax ImPressTM at any of the nearly 900 OfficeMax retail locations. To take supplies and print services. Take your card to the OfficeMax ImPressTM counter. With your first purchase

  19. Is Cleanliness Next to Godliness? The Role of Housekeeping in Impression Formation

    ERIC Educational Resources Information Center

    Harris, Paul B.; Sachau, Daniel

    2005-01-01

    We conducted a study to determine if the cleanliness of an apartment would affect observer impressions of the resident. Participants (210 female and 126 male undergraduate students) read a story in which a character's apartment was described as clean or dirty or in which no information about housekeeping was provided. For each condition, half the…

  20. Is Cleanliness Next to Godliness?The Role of Housekeeping in Impression Formation

    Microsoft Academic Search

    Paul B. Harris; Daniel Sachau

    2005-01-01

    We conducted a study to determine if the cleanliness of an apartment would affect observer impressions of the resident. Participants (210 female and 126 male undergraduate students) read a story in which a character’s apartment was described as clean or dirty or in which no information about housekeeping was provided. For each condition, half the characters were male and half

  1. Impressions of the Prison Rape Elimination Act: Wardens' Attitudes Toward, and Implementations of, the PREA

    E-print Network

    New Hampshire, University of

    Impressions of the Prison Rape Elimination Act: Wardens' Attitudes Toward, and Implementations of, the PREA Bethany Schmidt #12;Prison Rape Elimination Act (2003) Establish a zero-tolerance policy Prison rape as a top priority Increase available data through increased recording Develop national standards

  2. Antecedents of Impression Management Use and Effectiveness in a Structured Interview†

    Microsoft Academic Search

    Chad H. Van Iddekinge; Lynn A. McFarland; Patrick H. Raymark

    2007-01-01

    The authors examine personality variables and interview format as potential antecedents of impression management (IM) behaviors in simulated selection interviews. The means by which these variables affect ratings of interview performance is also investigated. The altruism facet of agreeableness predicted defensive IM behaviors, the vulnerability facet of emotional stability predicted self- and other-focused behaviors, and interview format (behavior description vs.

  3. Adolescents' Impressions of Antismoking Media Literacy Education: Qualitative Results from a Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Primack, Brian A.; Fine, Danielle; Yang, Christopher K.; Wickett, Dustin; Zickmund, Susan

    2009-01-01

    Although media literacy represents an innovative venue for school-based antismoking programming, studies have not systematically compared student impressions of these and traditional programs. This study utilized data from a randomized trial comparing these two types of programs. After each program, students responded to three open-ended questions…

  4. A surface impression and scanning electron microscopic study of porokeratosis of Mibelli.

    PubMed

    Menter, M A; Fourie, P B

    1977-04-01

    A silicone rubber impression technique, together with scanning electron microscopy, was used to study the surface detail of porokeratosis of Mibelli. The lesions are propagated by a bud-like spreading of the active edge. The keratotic rim is produced by the condensation of squamous cells from both within and without the lesion. PMID:861176

  5. Next Step towards a Learning Society?--Impressions from the Boardwalk of Atlantic City.

    ERIC Educational Resources Information Center

    Abrahamsson, Kenneth

    Impressions of Atlantic City can be used as an interesting case study for a discussion of the notion of a learning society and its survival in a policy-driven system like Sweden's and a market-influenced context such as Atlantic City. It would be interesting to draw a map of the different learning support systems that are available in various…

  6. Lasting First Impressions: A Qualitative Study of Freshmen Arrival on Campus.

    ERIC Educational Resources Information Center

    Michener, Barbara; Belcheir, Marcia J.

    This qualitative study examined the experiences and impressions of first-time freshmen at Boise State University (BSU) in Idaho. Twenty-five freshmen completed weekly open-ended interviews, kept journals, and participated in an end-of-term group meeting during the fall term of 1996. The results indicated that most students found getting…

  7. RISQUES ET MATRISE DES IMPRESSIONS POUR RENDRE COMPTE AU COMIT D'AUDIT

    E-print Network

    Paris-Sud XI, Université de

    to the audit committee is risky: the managers and auditors run the risk of losing their face. Key words : Audit1 RISQUES ET MAÎTRISE DES IMPRESSIONS POUR RENDRE COMPTE AU COMITÉ D'AUDIT Tiphaine Compernolle D'AUDIT Résumé : Comment se déroule la reddition de comptes à l'égard du comité d'audit ? Quels sont

  8. Correlation of cystoscopic impression with histologic diagnosis of biopsy specimens of the bladder

    Microsoft Academic Search

    Stephen J Cina; Jonathan I Epstein; Joseph M Endrizzi; William J Harmon; Thomas M Seay; Mark P Schoenberg

    2001-01-01

    There is a paucity of information in the contemporary literature that would permit assessment of the urologist's ability to endoscopically discriminate between benign and malignant lesions of the bladder or to predict the grade and stage of papillary neoplasms. This prospective study evaluates the correlation between cystoscopic impression of urothelial lesions and final histologic diagnoses. Sixty-four patients with 68 urothelial

  9. Effect of Route Complexity of Spatial Color Sequence on Human Color Impression and its Fuzzy Model

    Microsoft Academic Search

    Naotoshi SUGANO; Yuuichirou NEGISHI; Toshihiro ISHIHARA

    2009-01-01

    We examine how a toroidal sequence of the six fundamental colors affects human color impression. In order to investigate the different effects of spatial color sequences, we consider a hexagonal diagram that is a projection of RGB color space. The hexagonal diagram corresponds roughly to the hue circle indicated by both hue and saturation. The toroidal sequence is similar to

  10. Human color impressions elicited by well-ordered color signal sequence with minimum distance

    Microsoft Academic Search

    Naotoshi Sugano; Toshimasa Nasu

    2000-01-01

    The effects of different color signal sequences with the same several colors in the human color impressions were examined. Whether a several-color cyclic sequence has a minimum distance or not in the RGB color space was applied for subjects in an analysis of color sensations. In this study the degrees of pairs of terms applied to color (or color sequence)

  11. ARTC 4930 001 4 cr. hrs. Art Journaling -Textures and Impressions

    E-print Network

    Fernandez, Eduardo

    : Art journals or Visual journals are vital tactile workhorses that serve as windows into each of ourARTC 4930 001 4 cr. hrs. Art Journaling - Textures and Impressions Study Abroad ­ Orvieto, Italy: 561/289-4991 MDICOSOL@fau.edu Required Texts: Title: True Vision, Authentic Art Journaling. Author: L

  12. First Impressions of HIV Risk: It Takes Only Milliseconds to Scan a Stranger

    PubMed Central

    Renner, Britta; Schmälzle, Ralf; Schupp, Harald T.

    2012-01-01

    Research indicates that many people do not use condoms consistently but instead rely on intuition to identify sexual partners high at risk for HIV infection. The present studies examined neural correlates for first impressions of HIV risk and determined the association of perceived HIV risk with other trait characteristics. Participants were presented with 120 self-portraits retrieved from a popular online photo-sharing community (www.flickr.com). Factor analysis of various explicit ratings of trait characteristics yielded two orthogonal factors: (1) a ‘valence-approach’ factor encompassing perceived attractiveness, healthiness, valence, and approach tendencies, and (2) a ‘safeness’ factor, entailing judgments of HIV risk, trustworthiness, and responsibility. These findings suggest that HIV risk ratings systematically relate to cardinal features of a high-risk HIV stereotype. Furthermore, event-related brain potential recordings revealed neural correlates of first impressions about HIV risk. Target persons perceived as risky elicited a differential brain response in a time window from 220–340 ms and an increased late positive potential in a time window from 350–700 ms compared to those perceived as safe. These data suggest that impressions about HIV risk can be formed in a split second and despite a lack of information about the actual risk profile. Findings of neural correlates of risk impressions and their relationship to key features of the HIV risk stereotype are discussed in the context of the ‘risk as feelings’ theory. PMID:22291959

  13. Development and initial validation of the Impression Motivation in Sport Questionnaire-Team.

    PubMed

    Payne, Simon Mark; Hudson, Joanne; Akehurst, Sally; Ntoumanis, Nikos

    2013-06-01

    Impression motivation is an important individual difference variable that has been under-researched in sport psychology, partly due to having no appropriate measure. This study was conducted to design a measure of impression motivation in team-sport athletes. Construct validity checks decreased the initial pool of items, factor analysis (n = 310) revealed the structure of the newly developed scale, and exploratory structural equation modeling procedures (n = 406) resulted in a modified scale that retained theoretical integrity and psychometric parsimony. This process produced a 15-item, 4-factor model; the Impression Motivation in Sport Questionnaire-Team (IMSQ-T) is forwarded as a valid measure of the respondent's dispositional strength of motivation to use self-presentation in striving for four distinct interpersonal objectives: self-development, social identity development, avoidance of negative outcomes, and avoidance of damaging impressions. The availability of this measure has contributed to theoretical development, will facilitate research, and offers a tool for use in applied settings. PMID:23798591

  14. Improved impression cytology techniques for the immunopathological diagnosis of superficial viral infections

    PubMed Central

    Thiel, M; Bossart, W; Bernauer, W

    1997-01-01

    BACKGROUND—For epidemiological and therapeutic reasons early diagnosis of superficial viral infections is crucial. Conventional microbiological techniques are expensive, time consuming, and not sufficiently sensitive. In this study impression cytology techniques were evaluated to analyse their diagnostic potential in viral infections of the ocular surface.?METHOD—A Biopore membrane device instead of the original impression cytology technique was used to allow better quality and handling of the specimens. The impressions were processed, using monoclonal antibodies and immunoperoxidase or immunofluorescence techniques to assess the presence of herpes simplex virus, varicella zoster virus, or adenovirus antigens. Ocular surface specimens from healthy individuals (n=10) and from patients with suspected viral surface disease (n=19) were studied. Infected and non-infected cell cultures served as controls.?RESULTS—This modified technique of impression cytology allowed the collection of large conjunctival and corneal epithelial cell layers with excellent morphology. Immunocytological staining of these samples provided diagnostic results for all three viruses in patients with viral surface disease.?CONCLUSIONS—The use of Biopore membrane devices for the collection of ocular surface epithelia offers new diagnostic possibilities for external eye diseases. Immunopathological methods that are applied directly on these membrane devices can provide virological results within 1-4 hours. This contributes considerably to the clinical management of patients with infectious diseases of the ocular surface.?? PMID:9505824

  15. Dinosaur skin impressions from the Cretaceous of Korea: New insights into modes of preservation

    Microsoft Academic Search

    Jeong Yul Kim; Kyung Soo Kim; Martin G. Lockley; Seung Jo Seo

    2010-01-01

    Three specimens of sauropod dinosaur skin impressions from footprints in the Lower Cretaceous Jindong and Haman formations are unusual because they are not associated with well-preserved ‘host’ tracks. This suggests a hitherto unreported mode of preservation in which diagnostic but isolated skin traces may appear associated with substrates where only the superficial layers were originally soft. Two specimens from the

  16. Impression-Oriented Music Courseware and Its Application in Elementary Schools

    ERIC Educational Resources Information Center

    Sasaki, Shiori; Watagoshi, Kiku; Takano, Kosuke; Hirashima, Kazuo; Kiyoki, Yasushi

    2010-01-01

    Purpose: The purpose of this paper is to present the design and implementation of music courseware that features a music search system that uses impression keywords. The paper applies the courseware to "Kansei" (sensibility) development for elementary and junior high school students. The objectives of this courseware are to cultivate children's…

  17. Background music genre can modulate flavor pleasantness and overall impression of food stimuli.

    PubMed

    Fiegel, Alexandra; Meullenet, Jean-François; Harrington, Robert J; Humble, Rachel; Seo, Han-Seok

    2014-05-01

    This study aimed to determine whether background music genre can alter food perception and acceptance, but also to determine how the effect of background music can vary as a function of type of food (emotional versus non-emotional foods) and source of music performer (single versus multiple performers). The music piece was edited into four genres: classical, jazz, hip-hop, and rock, by either a single or multiple performers. Following consumption of emotional (milk chocolate) or non-emotional food (bell peppers) with the four musical stimuli, participants were asked to rate sensory perception and impression of food stimuli. Participants liked food stimuli significantly more while listening to the jazz stimulus than the hip-hop stimulus. Further, the influence of background music on overall impression was present in the emotional food, but not in the non-emotional food. In addition, flavor pleasantness and overall impression of food stimuli differed between music genres arranged by a single performer, but not between those by multiple performers. In conclusion, our findings demonstrate that music genre can alter flavor pleasantness and overall impression of food stimuli. Furthermore, the influence of music genre on food acceptance varies as a function of the type of served food and the source of music performer. PMID:24530691

  18. Nonverbal Behaviors and Initial Impressions of Trustworthiness in Teacher-Supervisor Relationships.

    ERIC Educational Resources Information Center

    Chamberlin, Carla R.

    2000-01-01

    Investigates the relationship between nonverbal behaviors of immediacy and dominance on teachers' initial impressions of trust toward a supervisor. Notes that supervisor immediacy resulted in higher perceptions of trust than supervisor dominance, and immediacy also rated higher on measures of appropriateness and effectiveness than dominance.…

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

    PubMed Central

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

    2015-01-01

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

  20. Impact of Internet Images: Impression-Formation Effects of University Web Site Images

    ERIC Educational Resources Information Center

    Ramasubramanian, Srividya; Gyure, James F.; Mursi, Nasreen M.

    2002-01-01

    Institutions of higher education are increasingly becoming dependent on Web-based marketing to reach out to their target audiences. The current empirical study examines the types of impressions formed by prospective students based on exposure to different university Web site images. A between-subjects experiment was conducted using four identical…

  1. 3700 Geary Blvd San Francisco, CA 94118 ImPress Contacts

    E-print Network

    Francisco, CA 94118 415.831.0478 sfsu.officemax@gmail.com Payment Options: · Pay with cash, check or credit: SFSU Password: 830impress830 Database: San Francisco State University D - Upload your file (you do not need to change any settings once you have browsed for your file) 2. SEND NOTIFICATION EMAIL TO: sfsu.officemax@gmail

  2. The Effect of Sex and Impression Management on Future Salary Estimations

    Microsoft Academic Search

    Robert A. Giacalone; Paul Rosenfeld

    1989-01-01

    Previous research has shown that American women are treated both verbally and nonverbally as lower in status than men (Henley & Freemen, 1981; Riess & Salzer, 1981). Impression-management research has found that people engage in less self-agrandizing and self-effacing behaviors for a low status, as opposed to a high status, audience (Schlenker, 1980). We found that undergraduates inflated or modestly

  3. UV-Curable Nanocomposite Based on Methacrylic-Siloxane Resin and Surface-Modified TiO2 Nanocrystals.

    PubMed

    Ingrosso, Chiara; Esposito Corcione, Carola; Striani, Raffaella; Comparelli, Roberto; Striccoli, Marinella; Agostiano, Angela; Curri, M Lucia; Frigione, Mariaenrica

    2015-07-22

    A novel UV-light-curable nanocomposite material formed of a methacrylic-siloxane resin loaded with 1 wt % oleic acid and 3-(trimethoxysilyl)propyl methacrylate silane (OLEA/MEMO)-coated TiO2 nanorods (NRs) has been manufactured as a potential self-curing structural coating material for protection of monuments and artworks, optical elements, and dental components. OLEA-coated TiO2 NRs, presynthesized by a colloidal chemistry route, have been surface-modified by a treatment with the methacrylic-based silane coupling agent MEMO. The resulting OLEA/MEMO-capped TiO2 NRs have been dispersed in MEMO; that is a monomer precursor of the organic formulation, used as a "common solvent" for transferring the NRs in prepolymer components of the formulation. Differential scanning calorimetry and Fourier transform infrared spectroscopy have allowed investigation of the effects of the incorporation of the OLEA/MEMO-capped TiO2 NRs on reactivity and photopolymerization kinetics of the nanocomposite, demonstrating that the embedded NRs significantly increase curing reactivity of the neat organic formulation both in air and inert atmosphere. Such a result has been explained on the basis of the photoactivity of the nanocrystalline TiO2 which behaves as a free-radical donor photocatalyst in the curing reaction, finally turning out more effective than the commonly used commercial photoinitiator. Namely, the NRs have been found to accelerate the cure rate and increase cross-linking density, promoting multiple covalent bonds between the resin prepolymers and the NR ligand molecules, and, moreover, they limit inhibition effect of oxygen on photopolymerization. The NRs distribute uniformly in the photocurable matrix, as assessed by transmission electron microscopy analysis, and increase glass transition temperature and water contact angle of the nanocomposite with respect to the neat resin. PMID:26151152

  4. Marginal and Internal Fit of Cobalt-Chromium Fixed Dental Prostheses Generated from Digital and Conventional Impressions

    PubMed Central

    Skjerven, Henrik; Carlsson, Pablo; Karlsson, Stig; Örtorp, Anders

    2014-01-01

    Objectives. Digital impressions are increasingly used and have the potential to avoid the problem of inaccurate impressions. Only a few studies to verify the accuracy of digital impressions have been performed. The purpose of this study was to compare the marginal and internal fit of 3-unit tooth supported fixed dental prostheses (FDPs) fabricated from digital and conventional impressions. Methods. Ten FDPs were produced from digital impressions using the iTero system and 10 FDPs were produced using vinyl polysiloxane (VPS) impression material. A triple-scan protocol and CAD software were used for measuring and calculating discrepancies of the FDPs at 3 standard areas: mean internal discrepancy, absolute marginal gap, and cervical area discrepancy. The Mann-Whitney U test was used for analyzing the results. Results. For conventional and digital impressions, respectively, FDPs had an absolute marginal gap of 147??m and 142??m, cervical area discrepancy of 69??m and 44??m, and mean internal discrepancy of 117??m and 93??m. The differences were statistically significant in the cervical and internal areas (P < 0.001). Significance. The results indicated that the digital impression technique is more exact and can generate 3-unit FDPs with a significantly closer fit compared to the VPS technique. PMID:24723954

  5. DESIGNING A HIGH RESOLUTION 3D IMAGING DEVICE FOR FOOTPRINT AND TIRE TRACK IMPRESSIONS AT CRIME SCENES1

    E-print Network

    Tuceryan, Mihran

    ...................................................................................................................................................18 #12;A high resolution 3d impression imaging device 2 1 INTRODUCTION In crime scene investigationsDESIGNING A HIGH RESOLUTION 3D IMAGING DEVICE FOR FOOTPRINT AND TIRE TRACK IMPRESSIONS AT CRIME SCENES1 TR-CIS-0416-12 Ruwan Egoda Gamage Abhishek Joshi Jiang Yu Zheng Mihran Tuceryan A Technical

  6. A survey of the methods of disinfection of dental impressions used in dental hospitals in the United Kingdom.

    PubMed

    Blair, F M; Wassell, R W

    1996-05-25

    The potential for cross-infection from microbial contaminated dental impressions has long been recognised. This study set out to investigate impression decontamination procedures currently used in UK dental hospitals (1995) and to see how these may have changed since a previous survey, carried out in 1988. A variety of disinfection solutions and regimes were highlighted both within and between dental hospitals. Several of the disinfecting solutions currently being used have not been specifically tested for efficacy with impression materials. The laboratories were asked to highlight any adverse reactions. Five laboratories reported that some alginates resulted in casts with poor surface properties when immersed in hypochlorite (0.1 and 1%), sodium dichloroisocyanurate, and 2% glutaraldehyde solutions. This paper highlights that there is no universally recognised impression disinfection/sterilisation protocol. It is recommended that all impressions should at least undergo a disinfecting procedure by immersion in 1% sodium hypochlorite for a minimum of 10 minutes. PMID:8652299

  7. Clinical success rates for polyether crown impressions when mixed dynamically and statically.

    PubMed

    Schmitter, Marc; Johnson, Glen H; Faggion, Clovis; Klose, Christina; Mitov, Gergo; Nothdurft, Frank P; Pospiech, Peter R; Rammelsberg, Peter; Ohlmann, Brigitte; Schwarz, Stefanie; Stober, Thomas; Schiller, Petra; Pritsch, Maria

    2012-06-01

    The purpose of this study is to compare success rates of dual-viscosity impressions for two types of mixing techniques of the polyether elastomeric impression material. Additionally, influencing parameters on the success rates should be evaluated. The expectation was that there would be no difference between the success rates for the two mixing techniques. Two centres enrolled 290 subjects (727 teeth) into the trial. Patients were randomized for the two types of mixing techniques. One step, dual-viscosity impressions were made with either statically mixed Impregum Soft tray material (SAM) or dynamically mixed Impregum Penta H DuoSoft (DMM). Low viscosity Impregum Garant L DuoSoft was used for both groups. Gingival displacement involved the use of two braided cords. Full-arch trays were used exclusively. Both critical defects and operator errors were assessed for the first impression taken by trained dentists. The primary outcome was impression success. For comparison of the two mixing techniques, the odds ratio for success and the corresponding one-sided 95% confidence interval was calculated by a logistic regression model. To account for the dependence between several teeth within one patient, the method of general estimating equations was used. The overall impression success rate was 35.4%. Both mixing techniques showed equal success rates indicated by an OR of 1.0 and a lower limit of the one-sided 95% confidence interval of 0.71. Using this result to develop the corresponding interval for the difference, it could be shown that the success rate using SAM was at most 8.2% lower than that when using DMM with a probability of 95%. Multivariate logistic regression analysis of other potential influencing factors showed position of finish line (p = 0.008, supra compared to mixed), blood coagulation disorder (p = 0.021) and the level of training of the clinician (student vs dentist, p=0.008) to have an independent influence on the success rate. Dynamic mechanical mixing and the new static mixing of polyether tray material showed nearly equal success rates in the study even though success rates were comparatively low (DMM, 35.3%; SAM, 35.4%). PMID:21611728

  8. [The influence of disinfectants on colloidal impression materials and dental stones].

    PubMed

    Oshima, Y; Yoshida, T

    1989-06-01

    In view of prophylaxis against hospital infections, following tests were performed: Two kinds of alginate impression materials (ALGIACE and Aligix-S) and two kinds of agar impression materials (CARTRIILLOID and RUBBERLLOID) were immersed for 30 minutes in the following six kinds of disinfectants; 0.1% benzethonium chloride (benzethonium), 1% chlorhexidine gluconate (hexidine), 1% chlorhexidine gluconate added with surfactants (hexidine surfactant), 1% sodium hypochlorite (hypochlorous acid), 2% glutaraldehyde (glutaral) and 1% formaldehyde (formalin). Changes in size of the impression materials with time were then measured. Three kinds of dental stones (SHIMOMURA DENTAL PLASTER, NEW PLASTONE and SURSTONE) were infused into the impression surfaces after treatment with disinfectants, and the surface roughness and hardness of the yielded surfaces of the samples were measured. The results obtained are as follows: 1) As to ALGIACE, although the rates of changes in size lay within the range of +/- 0.3% when immersed in hexidine, hexidine surfactant and hypochlorous acid, the infusion of either one of SHIMOMURA DENTAL PLASTER, NEW PLASTONE or SURSTONE into the impression showed an effect on the stone surface. 2) As to Algix-S, the rate of changes in size lay within the range of +/- 0.3% when immersed in all the disinfectants, and the influsions of NEW PLASTONE and SURSTONE after immersing in benzethonium, hexidine surfactant and glutaral gave a slight effect on the stone surface. 3) As to CARTRILLOID, the rates of change in size lay within the range of +/- 0.3% except for the immersion in hexidine; the influsion of SHIMOMURA DENTAL PLASTER into the impression, the influsion of NEW PLASTONE after immersing in benzethonium and formalin and the influsions of NEW PLASTONE and SURSTONE after immersing in glutaral gave a slight effect on teh stone surface. 4) As to RUBBERLLOID, the rates of changes in size lay within the range of +/- 0.2% when immersed each disinfectant; the influsion of SHIMOMURA DENTAL PLASTER after immersing in hypochlorous acid and that of either one of SHIMOMURA DENTAL PLASTER, NEW PLASTONE or SURSTONE after immersing in benzethonium, glutaral and formalin gave a slight effect on the stone surface. PMID:2637422

  9. Modern Impressions

    ERIC Educational Resources Information Center

    Simkus, Joyce

    2010-01-01

    Claude Monet and the Impressionists were the forward thinkers and painters of their time. They used quick brushstrokes and a rapid pace to capture lively outdoor scenes. Inspired by the colors and shadows revealed by sunlight, the Impressionists typically worked outside, without many preliminary sketches or drafts. This was in direct contrast to…

  10. Unique Impressions

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2008-01-01

    For much of the 20th century, it was the engine that powered one of nation's most massive retail operations. By the beginning of the 21st century, the historic building was no longer needed to supply energy to what remained of the once bustling Sears, Roebuck and Co. campus on the West Side of Chicago. The original purpose of the Power House, as…

  11. Effect of mixing method on rheological properties of alginate impression materials.

    PubMed

    Inoue, K; Song, Y X; Kamiunten, O; Oku, J; Terao, T; Fujii, K

    2002-07-01

    The apparent viscosity of alginate impression paste prepared by three mixing methods (hand-mixing technique (HM), semiautomatic instrument (SM) and automatic mixing instrument (AM)), and the gel strength and surface depression of the respective set materials were measured. The materials used were eight commercially available products mixed at a temperature of 23 +/- 0.5 degrees C and allowed to set. The AM had a high mixing speed, which reduced the working time 4.4-31.5%, compared with HM. This was the result of an increase in paste temperature during mixing. In the case of impression materials mixed with the AM, the gel strength and the surface depression at the gel fracture increased significantly, in accordance with Fisher's protected least significant difference (PLSD) analysis. This phenomenon is caused by a decrease of air bubbles in the set material. PMID:12153449

  12. Cyclosporine Effects on Clinical Findings and Impression Cytology Specimens in Severe Vernal Keratoconjunctivitis

    Microsoft Academic Search

    Avni Murat Avunduk; Mustafa Cihat Avunduk; Hidayet Erdöl; Zerrin Kapicioglu; Nurettin Akyol

    2001-01-01

    Purpose: To investigate the possible effects of topical cyclosporine eye drops 2% (CsA) on conjunctival immune cells obtained by impression cytology technique and to determine the clinical relevance of this effect if present. Methods: Ten consecutive patients with severe, resistant, and active vernal keratoconjunctivitis (VKC) were included in this study. All of them were treated with 2% of topical CsA

  13. Craniocervical growth collision: another explanation of the Arnold-Chiari malformation and of basilar impression

    Microsoft Academic Search

    M. Roth

    1986-01-01

    Analysis of neuro-cranio-spinal development suggests a cranio-cervical growth conflict as the cause of the Arnold-Chiari malformation and of basilar impression. The ascending course and elongation of the upper cervical nerves associated with the Arnold-Chiari malformation reflects the abnormal, caudo-cranially proceeding growth of the cervical spine. This is the opposite of the normal cranio-caudal direction of growth (which includes the brain)

  14. Donepezil (Aricept®) treatment of multi infarct dementia: The caregivers and clinical impression

    Microsoft Academic Search

    J. R. Shua-Haim; Vered Shua-Haim; Eric Comsti; J. S. Ross

    2000-01-01

    The purpose of this study was to investigate the clinical and caregivers impression of Aricept ® treatment in patients suffering from Multi-Infarct Dementia (MID).In a prospective study 73 MID patients1 were treated with Donepezil (Aricept®) for 16-to 20-weeks. Donepezil was administered as a 5mg tablet once daily at bedtime. After four weeks, patients tolerant of the 5-mg dose were increased

  15. Method and apparatus for non-destructive evaluation of composite materials with cloth surface impressions

    NASA Technical Reports Server (NTRS)

    Madras, Eric I. (inventor)

    1995-01-01

    A method and related apparatus for nondestructive evaluation of composite materials by determination of the quantity known as Integrated Polar Backscatter, which avoids errors caused by surface texture left by cloth impressions by identifying frequency ranges associated with peaks in a power spectrum for the backscattered signal, and removing such frequency ranges from the calculation of Integrated Polar Backscatter for all scan sites on the composite material is presented.

  16. Water-soluble mitochondria-specific ytterbium complex with impressive NIR emission.

    PubMed

    Zhang, Tao; Zhu, Xunjin; Cheng, Chopen C W; Kwok, Wai-Ming; Tam, Hoi-Lam; Hao, Jianhua; Kwong, Daniel W J; Wong, Wai-Kwok; Wong, Ka-Leung

    2011-12-21

    A water-soluble porphyrinato ytterbium complex linked with rhodamine B (Yb-2) showed mitochondria-specific subcellular localization and strong two-photon-induced NIR emissions (?(em) = 650 nm, porphyrinate ligand ? ? ?* transition; ?(em) = 1060 nm, Yb(III) (5)F(5/2) ? (5)F(7/2) transitions; ?(2) = 375 GM in DMSO) with an impressive Yb(III) NIR emission quantum yield (1% at ?(ex) = 340 nm; 2.5% at ?(ex) = 430 nm) in aqueous solution. PMID:22103884

  17. A Comparative Evaluation of the Dimensional Stability of Three Different Elastomeric Impression Materials after Autoclaving – An Invitro Study

    PubMed Central

    Thota, Kiran Kumar; Ravuri, Rajyalakshmi; Tella, Suchita

    2014-01-01

    Aim of the Study: The purpose of the study was to determine the effect of autoclaving on the dimensional stability of three different elastomeric impression materials at three different time intervals. Materials and Methods: Standardized stainless steel master die as per ADA specification number 19 was fabricated. The impression materials used for the study were condensation silicone (GP1), addition silicone (GP2) and polyether (GP3). A total of 45 samples of the stainless steel die were made (n = 45), that is 15 samples for each group. Impression materials were mixed according to the manufacturer’s instructions and were loaded into the mold to make an impression of the die. Impressions were identified with the help of numerical coding system and measurements were made using stereomicroscope (MAGNUS MSZ-Bi) of 0.65x magnification with the help of image analysis software (IMACE PRO-INSIGHT VERSION.The results were subjected to statistical analysis using one way analysis of variance and student t-test for comparison between the groups. Results: Within the limitations of the study statistically significant dimensional changes were observed for all the three impression materials at three different time intervals but this change was not clinically significant. Conclusion: It is well-known fact that all impressions should be disinfected to avoid possible transmission of infectious diseases either by direct contact or cross contamination. Immersion and spray disinfection as well as various disinfection solutions have been tested and proven to be effective for this purpose. But for elastomeric impression materials these methods have proven to be ineffective as they do not prevent cross contamination among the dental team. So autoclaving was one of the most effective sterilization procedure for condensation silicone and addition silicone. Since polyether is hydrophilic it is better to disinfect the impressions as recommended by the manufacturer or by immersion or spray atomization. PMID:25478447

  18. Effect of bite tray impression technique on relocation accuracy in frameless stereotactic radiotherapy

    SciTech Connect

    Herbert, Clare E.; Ebert, Martin A.; Barclay, D.; Whittall, David S.; Joseph, David J.; Harper, Chris S.; Spry, Nigel A

    2003-03-31

    A previously developed method for achieving patient relocation in fractionated stereotactic radiotherapy (attachment of an infrared fiducial system to a bite tray) relies on the integrity of a bite tray system that incorporates moulding to the patient's upper dentition. Reproducible and accurate patient positioning requires stability of the bite tray and mould during the full treatment process, both during the time the bite tray is inserted in the patient's mouth, and between separate bite tray insertions. The optimum construction method for a stable reproducible tray has not been sufficiently investigated. We undertook a study to identify factors which might influence the integrity of the hard palate bite tray system. Reprosil Fast Set Putty was used to construct 3 impression conditions; teeth only; teeth and alveolar sulcus; and teeth, alveolar sulcus, and the hard palate. Reproducibility was assessed by volunteers inserting the impressions multiple times and recording the locations of 8 standard reference points. Our results showed the optimal impression technique (i.e., the one that led to the smallest ranges in positional and rotational errors) was that which incorporated the teeth, alveolar sulcus, and hard palate.

  19. Synthesis and dielectric studies of polyorthotoluidine-polyvinyl pyrrolidone conducting polymer composites

    NASA Astrophysics Data System (ADS)

    Himanshu, A. K.; Bahuguna, Rajni; Ray, D. K.; Bandyopadyayay, S. K.; Sinha, T. P.

    2013-02-01

    The intrinsically conducting polymer, polyorthotoluidine (POT) has been synthesized by chemical polymerization process with the help of water-soluble support polymer polyvinyl pyrrolidone (PVP)). The dielectric measurement of POT-PVP was measured in the temperature range from 308-398 K at frequency 10 kHz. The temperature dependent data has been analyzed in the framework of dielectric permittivity, loss tangent and ac conductivity. Above the temperature 345 K, conductivity shows weak temperature dependence. This is an important feature with respect to technological applications of POT-PVP as an electro-inactive material at high temperature.

  20. Occupational exposure to diisononyl phthalate (DiNP) in polyvinyl chloride processing operations

    Microsoft Academic Search

    Cynthia J. Hines; Nancy B. Hopf; James A. Deddens; Manori J. Silva; Antonia M. Calafat

    Purpose  Diisononyl phthalate (DiNP) is primarily used as a plasticizer in polyvinyl chloride (PVC) materials. While information is\\u000a available on general population exposure to DiNP, occupational exposure data are lacking. We present DiNP metabolite urinary\\u000a concentrations in PVC processing workers, estimate DiNP daily intake for these workers, and compare worker estimates to other\\u000a populations.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  We assessed DiNP exposure in participants from

  1. Preparation and Characterization of Palm Leaf Incorporated Polyvinyl Alcohol Bio Composites

    NASA Astrophysics Data System (ADS)

    Patel, Arunendra Kumar; Bajpai, Rakesh; Keller, J. M.; Saha, Abhijit

    2011-12-01

    The Bio Composites of palm leaf (PL) incorporated polyvinyl alcohol (PVA) has been prepared using solution cast technique. Structural and microhardness properties of pure PVA and PL filled PVA Bio Composites has been determined by using FTIR and Vicker's indentation techniquque respectively. The FTIR analysis reveals the presence of PL moieties in PVA, which indicates the good compatibility between PL and PVA. The values of microhardness increases in all composition of PL incorporated PVA films as compared to the pure PVA. This increment in the microhardness is attributed to the excellent binding of PL into PVA.

  2. Synthesis of Nanocomposites of Polyvinyl Alcohol with Silver Nanoparticles and Their Use

    NASA Astrophysics Data System (ADS)

    Bhat, N. V.; Karmakar, N. S.; Kothari, D. C.

    2013-08-01

    Composites of polyvinyl alcohol (PVA) containing silver nanoparticles were prepared using in situ synthesis of nanoparticles. Structure and properties of these composites were investigated using UV-Vis spectroscopy, XRD, DSC, SEM and AFM. The studies show that PVA can reduce the AgNO3 to yield silver nanoparticles and in the process forms bonds with PVA chains. The anti-bacterial properties of these films were studied by qualitative as well as quantitative methods which gave the values of 98% for gram positive and 89% for gram negative bacteria.

  3. Phosphonium-based ionic liquids as modifiers for biomedical grade poly(vinyl chloride)

    Microsoft Academic Search

    Ana M. A. Dias; Sofia Marceneiro; Mara E. M. Braga; Jorge F. J. Coelho; Abel G. M. Ferreira; Pedro N. Simões; Helena I. M. Veiga; Liliana C. Tomé; Isabel M. Marrucho; José M. S. S. Esperança; Ana A. Matias; Catarina M. M. Duarte; Luís P. N. Rebelo; Hermínio C. de Sousa

    This work reports and discusses the influence of four phosphonium-based ionic liquids (PhILs), namely of trihexyl(tetradecyl) phosphonium dicyanamide, [P6,6,6,14][dca]; trihexyl(tetradecyl) phosphonium bis(trifluoromethylsulfonyl)imide, [P6,6,6,14][Tf2N]; tetrabutyl phosphonium bromide, [P4,4,4,4][Br] and tetrabutyl phosphonium chloride, [P4,4,4,4][Cl], on some of the chemical, physical and biological properties of biomedical grade suspension poly(vinyl chloride) (PVC). The main goal of this work was to evaluate the capacity of

  4. Poly(vinyl alcohol-co-lactic acid)\\/Hydroxyapatite Composites: Synthesis and Characterization

    Microsoft Academic Search

    Nita TudorachiAurica; Aurica P. Chiriac

    2011-01-01

    There is a wide range of applications where calcium phosphate and hydroxyapatite (HA) are used as biomaterials, e.g. as synthetic\\u000a bone grafts, coating on metal prostheses (like hip endoprostheses or dental implants) and drug carriers. In the study, the\\u000a design and synthesis of composites based on poly(vinyl alcohol-co-lactic acid)\\/hydroxyapatite (PVA-co-LA\\/HA) with potential\\u000a for biomedical applications, they are presented. The hydroxyapatite

  5. Superselective arterial embolisation with a liquid polyvinyl alcohol copolymer in patients with acute gastrointestinal haemorrhage

    Microsoft Academic Search

    Markus Lenhart; Christian Paetzel; Michael Sackmann; Hans Schneider; Ernst Michael Jung; Andreas G. Schreyer; Stefan Feuerbach; Niels Zorger

    2010-01-01

    Objectives  To evaluate the results of emergency embolisation in acute arterial bleeding of the gastrointestinal tract with a liquid polyvinyl\\u000a alcohol copolymer from two centres.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  We retrospectively analysed 16 cases (15 patients) of acute arterial bleeding of the gastrointestinal tract where emergency\\u000a embolotherapy was performed by using the copolymer when acute haemorrhage was not treatable with endoscopic techniques alone.\\u000a Cause of

  6. Sliding of poly(vinyl chloride) on metals studied by Auger electron spectroscopy

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    The sliding of polyvinyl chloride on nickel, iron and S-Monel has been studied by Auger electron spectroscopy. Polymer was not transferred to the metals, rather shear appeared to take place at the interface. The metal was progressively chlorinated as the polymer made multiple passes on the surface. The thickness of this chlorine film was the order of one atomic layer. Electron-induced desorption studies indicate that the chlorine is chemisorbed to the metal. These results are interpreted as evidence for mechanically induced and/or thermal degradation of the polymer during sliding. Degradation products of HCl and Cl2 which chemisorb to the metal are evolved near the interface.

  7. DSC studies of poly(vinyl chloride)\\/poly(?-caprolactone)\\/poly(?-caprolactone)-b-poly(dimethylsiloxane) blends

    Microsoft Academic Search

    Claudia Gordin; Christelle Delaite; Sophie Bistac; Daniela Rusu; Mihai Rusu

    2009-01-01

    Poly(vinyl chloride)\\/poly(?-caprolactone)\\/poly(?-caprolactone)-b-poly(dimethylsiloxane) [PVC\\/PCL\\/(PCL-b-PDMS)] blends were\\u000a prepared by solvent casting from tetrahydrofuran. The content of PVC was kept constant (60 wt%); the PCL and PCL-b-PDMS contents\\u000a were varied by replacing different amounts of PCL [0–20 wt% from the PVC\\/PCL (60\\/40) blend] with PCL-b-PDMS copolymer having\\u000a different molecular weights of the PCL blocks. The thermal properties of prepared blends were investigated by

  8. First metacarpal resurfacing with polyvinyl alcohol implant in osteoarthritis: preliminary study.

    PubMed

    Taleb, C; Berner, S; Mantovani Ruggiero, G

    2014-06-01

    Osteoarthritis of first carpometacarpal (CMC) joint is a condition that is frequently encountered in hand surgery. If conservative treatment fails, several surgical procedures are available ranging from arthroscopic debridement to total joint arthroplasty. This study focuses on a new resurfacing technique for the base of the first metacarpal using a polyvinyl alcohol hydrogel implant. Our preliminary study found good clinical outcomes and no inflammatory reaction after a follow-up of 30 months. However prospective studies with a longer follow-up and more patient are needed to confirm these results. PMID:24880607

  9. Grafting of poly(vinyl pyrrolidone) with citric acid using gamma irradiation

    NASA Astrophysics Data System (ADS)

    Ajji, Zaki

    2007-12-01

    Ternary mixtures of poly(vinyl pyrrolidone) (PVP), citric acid (CA) and water were irradiated at various gamma ray doses. Copolymer swelling and gelation% were determined with respect to the irradiation dose and PVP/CA composition. The gelation% increases with increasing the irradiation dose, but decreases with increasing the CA content in the graft copolymer. The swelling% of the prepared hydrogels decreases with increasing the irradiation dose and CA content in the copolymer, as a result of an increase in the crosslink density and the hydrogen bonds, respectively. The ion exchange capacity and the uptake of uranyl ions increase with increasing the CA content in the graft copolymer.

  10. Monitoring of Temperature Fatigue Failure Mechanism for Polyvinyl Alcohol Fiber Concrete Using Acoustic Emission Sensors

    PubMed Central

    Li, Dongsheng; Cao, Hai

    2012-01-01

    The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed. PMID:23012555

  11. Polyvinyl alcohol-cellulose nanofibrils-graphene oxide hybrid organic aerogels.

    PubMed

    Javadi, Alireza; Zheng, Qifeng; Payen, Francois; Javadi, Abdolreza; Altin, Yasin; Cai, Zhiyong; Sabo, Ronald; Gong, Shaoqin

    2013-07-10

    Hybrid organic aerogels consisting of polyvinyl alcohol (PVA), cellulose nanofibrils (CNFs), and graphene oxide nanosheets (GONSs) were prepared using an environmentally friendly freeze-drying process. The material properties of these fabricated aerogels were measured and analyzed using various characterization techniques including compression testing, scanning electron microscopy, thermogravimetric (TGA) analysis, Brunauer-Emmet-Teller (BET) surface area analysis, and contact angle measurements. These environmentally friendly, biobased hybrid organic aerogels exhibited a series of desirable properties including a high specific compressive strength and compressive failure strain, ultralow density and thermal conductivity, good thermal stability, and moisture resistance, making them potentially useful for a broad range of applications including thermal insulation. PMID:23789837

  12. Effect of borax concentration on the structure of Poly(Vinyl Alcohol) gels

    NASA Astrophysics Data System (ADS)

    Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

    2012-06-01

    Poly(Vinyl Alcohol) hydrogels cross-linked with varying concentrations of borax have been studied using Small-Angle Neutron Scattering and X-Ray Diffraction. The intensity of scattering increases with borax concentration from 1 mg/ml up to 2 mg/ml and falls thereafter for 4 mg/ml, increasing again for a concentration of 10 mg/ml. The mesoscopic structural changes that cause these trends in the SANS data are in keeping with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.

  13. Light scattering and viscoelasticity study of poly(vinyl alcohol)–borax aqueous solutions and gels

    Microsoft Academic Search

    Hsiu-Li Lin; Yuan-Feng Liu; T. Leon Yu; Wen-Horng Liu; Syang-Peng Rwei

    2005-01-01

    Poly(vinyl alcohol)–borate (PVA–borate) aqueous solutions properties with PVA concentrations ranging from 2 to 60g\\/L and borax concentrations of 0.0 and 0.2M were investigated at room temperature using static and dynamic light scattering (SLS and DLS), and dynamic viscoelasticity measurements. Light scattering and viscoelasticity data revealed that all the PVA–borate aqueous systems, except those with [PVA]?40g\\/L and [borax]=0.2M, behaved as solutions.

  14. Copper Doped Methylene Blue Sensitized Poly(vinyl alcohol)-Acrylamide Films for Stable Diffraction Efficiency

    NASA Astrophysics Data System (ADS)

    John, Beena Mary; Joseph, Rani; Sreekumar, K.; Sudha Kartha, C.

    2006-11-01

    Copper doped methylene blue sensitized poly(vinyl alcohol) (MBPVA)-acrylamide films were fabricated to improve the storage life of recorded gratings. The films were fabricated using gravity settling method and the copper chloride concentration was optimized as 3.18× 10-3 mol/l for a dye concentration of 6.2× 10-4 mol/l. The gratings recorded on the optimized film constitution could be stored for months with stable diffraction efficiency (24%) without any chemical or thermal fixing techniques. The resolution of the material is found to be unaffected with the addition of copper chloride.

  15. Tetraethylorthosilicate reaction rates on SiO{sub 2} at 1000 K: Zero-order dependence on hydroxyl coverage and implications for reactions with three-membered siloxane rings

    SciTech Connect

    Bartram, M.E.; Moffat, H.K. [Chemical Processing Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-0601 (United States)] [Chemical Processing Sciences Department, Sandia National Laboratories, Albuquerque, New Mexico 87185-0601 (United States)

    1996-05-01

    We have determined key kinetic parameters for the reaction of tetraethylorthosilicate (TEOS) on SiO{sub 2}. This was accomplished under conditions (20{endash}500 mTorr at 1000 K) that pertain directly to TEOS-based chemical vapor deposition processes. TEOS reactions were carried out using deuterated silanols (SiOD) on the initial SiO{sub 2} surface. This allowed Fourier transform infrared spectroscopy measurements to distinguish the consumption of SiOD by TEOS from the concurrent formation of SiOH which results from TEOS decomposition at 1000 K. While SiOD consumption did exhibit a first-order dependence on SiOD coverage, TEOS decomposition exhibited a zero-order dependence on the total coverage of hydroxyl groups. This suggests that reactions with hydroxyl groups alone cannot account for all of the TEOS decomposition reactions at 1000 K. Since the low coverage of two-membered siloxane [(Si{endash}O){sub 2}] rings was consumed during the initial TEOS exposure, siloxane (Si{endash}O{endash}Si) bridges in three-membered siloxane [(Si{endash}O){sub 3}] rings may be the additional species responsible for the constant rate of TEOS decomposition. However, it is not conclusive that this type of site-specific mechanism controls the chemistry. The data may also be explained with a site-independent mechanism in which intramolecular decomposition of TEOS on the surface provides a common rate-determining step for subsequent consumption of hydroxyls and siloxane bridges on SiO{sub 2}. Regardless of the specific mechanism, our results predict that deposition rates will be insensitive to the relative coverages of siloxane bridges and hydroxyls on SiO{sub 2}. Therefore, a precise knowledge of the coverages of these species on SiO{sub 2} is not essential for modeling thermal TEOS decomposition rates. {copyright} {ital 1996 American Vacuum Society}

  16. TEOS reaction rates on SiO{sub 2} at 1000K: Zero-order dependence on hydroxyl coverage and implications for reactions with three-membered siloxane rings

    SciTech Connect

    Bartram, M.E.; Moffat, H.K.

    1995-12-01

    We have determined key kinetic parameters for the reaction of TEOS (tetraethylorthosilicate) on SiO{sub 2}. This was accomplished under conditions (20 to 500 mTorr at 1000 K) that pertain directly to TEOS-based CVD (chemical vapor deposition) processes. TEOS reactions were carried out using deuterated silanols (SiOD) on the initial SiO{sub 2} surface. This allowed FTIR (Fourier transform infrared spectroscopy) measurements to distinguish the consumption of SiOD by TEOS from the concurrent formation of SiOH which results from TEOS decomposition at 1000 K. While SiOD consumption did exhibit a first-order dependence on SiOD coverage, SiOH formation exhibited a zero-order dependence on the total coverage of hydroxyl groups. This suggests that reactions with hydroxyl groups alone can not account for all of the TEOS decomposition reactions at 1000 K. Since the low coverage of two-membered siloxane ((Si-O){sub 2}) rings was consumed during the initial TEOS exposure, siloxane (Si-O-Si) bridges in three-membered siloxane ((Si-O){sub 3}) rings may be the additional species responsible for the constant rate of TEOS decomposition. However, it is not conclusive that this type of site-specific mechanism controls the chemistry. The data may also be explained with a site-independent mechanism in which intramolecular decomposition of TEOS on the surface provides a common rate-determining step for subsequent consumption of hydroxyls and siloxane bridges on SiO{sub 2}. Regardless of the specific mechanism, our results predict that deposition rates will be insensitive to the relative coverages of siloxane bridges and hydroxyls on SiO{sub 2}. Therefore, a precise knowledge of the coverages of these species on SiO{sub 2} is not essential for modeling thermal TEOS decomposition rates.

  17. RNA-RNA in situ hybridization using DIG-labeled probes: the effect of high molecular weight polyvinyl alcohol on the alkaline phosphatase

    E-print Network

    Franks, Robert

    polyvinyl alcohol on the alkaline phosphatase indoxyl-nitroblue tetrazolium reaction Marc DeBlock and Dirk digoxigenin-labeled probes: the use of high molecular weight polyvinyl alcohol in the alkaline phosphatase protocol us- ing alkaline phosphatase-conjugated digoxi- genin- (DIG-) labeled probes is presented

  18. Cost-effectiveness of silicone and alginate impressions for complete dentures

    PubMed Central

    Hulme, C.; Yu, G.; Browne, C.; O’Dwyer, J.; Craddock, H.; Brown, S.; Gray, J.; Pavitt, S.; Fernandez, C.; Godfrey, M.; Dukanovic, G.; Brunton, P.; Hyde, T.P.

    2014-01-01

    Objective The aim of this study was to assess the cost effectiveness of silicone and alginate impressions for complete dentures. Methods Cost effectiveness analyses were undertaken alongside a UK single centre, double blind, controlled, crossover clinical trial. Taking the perspective of the healthcare sector, effectiveness is measured using the EuroQol (EQ-5D-3L) which provides a single index value for health status that may be combined with time to produce quality adjusted life years (QALYs); and Oral Health Impact Profile (OHIP-EDENT). Incremental cost effectiveness ratios are presented representing the additional cost per one unit gained. Results Mean cost was higher in the silicone impression group (£388.57 vs. £363.18). Negligible between-group differences were observed in QALY gains; the silicone group had greater mean OHIP-EDENT gains. The additional cost using silicone was £3.41 per change of one point in the OHIP-EDENT. Conclusions The silicone group was more costly, driven by the cost of materials. Changes in the EQ-5D and QALY gains over time and between arms were not statistically significant. Change in OHIP-EDENT score showed greater improvement in the silicone group and the difference between arms was statistically significant. Given negligible QALY gains and low level of resource use, results must be treated with caution. It is difficult to make robust claims about the comparative cost-effectiveness. Clinical significance Silicone impressions for complete dentures improve patients’ quality of life (OHIP-EDENT score). The extra cost of silicone impressions is £30 per patient. Dentists, patients and health care funders need to consider the clinical and financial value of silicone impressions. Different patients, different dentists, different health funders will have individual perceptions and judgements. ISRCTN01528038. NIHR-RfPB grant PB-PG-0408-16300.?? This article forms part of a project for which the author (TPH) won the Senior Clinical Unilever Hatton Award of the International Assocation for Dental Research, Capetown, South Africa, June 2014. PMID:24995472

  19. Acute health effects among firefighters exposed to a polyvinyl chloride (PVC) fire

    SciTech Connect

    Markowitz, J.S.; Gutterman, E.M. (New York State Psychiatric Institute (USA)); Schwartz, S.; Link, B.; Gorman, S.M. (Columbia Univ., New York (USA))

    1989-05-01

    Firefighters are frequently being called on to fight fires that are chemical in nature. In the aftermath of a chemical fire in Plainfield, New Jersey on March 20-21, 1985, the authors conducted a retrospective cohort study which surveyed 80 firefighters exposed to burning polyvinyl chloride (PVC) as well as 15 nonexposed firefighter subjects. By means of an 81-item symptom checklist, exposed firefighters reported more frequent and severe symptoms at 5-6 weeks post incident. This was true for a total symptomatology score as well as 19 individual items. Some of the items with an elevated risk were consistent with exposure to hydrogen chloride, the main pyrolysis product of polyvinyl chloride. Other items with an elevated risk appeared to be related to smoke inhalation while others seemed psychosocial in nature. Analyses conducted within the exposed firefighter group showed that fighting the fire the first day, being a truckman, and residence within 1 mile (1.6 km) of the firehouse were significant risk factors for high total symptom scores. These risk factors may have been associated with level or duration of exposure to the toxic substances produced during the fire.

  20. Cosolvent gel-like materials from partially hydrolyzed poly(vinyl acetate)s and borax.

    PubMed

    Angelova, Lora V; Terech, Pierre; Natali, Irene; Dei, Luigi; Carretti, Emiliano; Weiss, Richard G

    2011-09-20

    A gel-like, high-viscosity polymeric dispersion (HVPD) based on cross-linked borate, partially hydrolyzed poly(vinyl acetate) (xPVAc, where x is the percent hydrolysis) is described. Unlike hydro-HVPDs prepared from poly(vinyl alcohol) (PVA) and borate, the liquid portion of these materials can be composed of up to 75% of an organic cosolvent because of the influence of residual acetate groups on the polymer backbone. The effects of the degree of hydrolysis, molecular weight, polymer and cross-linker concentrations, and type and amount of organic cosolvent on the rheological and structural properties of the materials are investigated. The stability of the systems is explored through rheological and melting-range studies. (11)B NMR and small-angle neutron scattering (SANS) are used to probe the structure of the dispersions. The addition of an organic liquid to the xPVAc-borate HVPDs results in a drastic increase in the number of cross-linked borate species as well as the agglomeration of the polymer into bundles. These effects result in an increase in the relaxation time and thermal stability of the networks. The ability to make xPVAc-borate HVPDs with very large amounts of and rather different organic liquids, with very different rheological properties that can be controlled easily, opens new possibilities for applications of PVAc-based dispersions. PMID:21848256

  1. Deep ultraviolet photoresist based on tungsten polyoxometalates and poly(vinyl alcohol) for bilayer photolithography

    SciTech Connect

    Carls, J.C.; Argitis, P.; Heller, A. (Dept. of Chemical Engineering, Univ. of Texas at Austin, Austin, TX (US))

    1992-03-01

    In this paper a negative tone deep ultraviolet resist, a mixture of phosphotungstic acid and poly(vinyl alcohol) is described. This resist has {lt}100 mJ cm{sup {minus}2} sensitivity and resolves {le}0.3 {mu}m features. Even though the photochemistry involves chemical amplification, the exposed patterns are stable and the process tolerates hours between the exposure and the post-bake steps. The resist is spun from an aqueous solutio, and its wet processing is also aqueous. This resist is used in a bilayer scheme, where advantage is taken of both the resistance of the tungsten oxide to oxygen plasmas and its easy stripping in fluorine-containing plasmas. Because poly(vinyl alcohol) is intrisincally a wetting agent, pinhole-free resist films of {approximately}1000 {Angstrom} thickness can be spun. These thin coatings provide sufficient oxygen plasma etch resistance to allow patterning of a thick 1.5 {mu}m novolac planarizing layer underneath the resist.

  2. A sectional-splinting technique for impressing multiple implant units by eliminating the use of an open tray

    PubMed Central

    Deogade, Suryakant C.; Dube, Gunjan

    2014-01-01

    Since the inception of root form implant dentistry by P-I Branemark in the early 1980's, so many technical advances have been put forward by several authors. However, the open tray impression technique is still performed for impressing multiple implant fixtures as it was first described in the original Branemark procedure manual. The most critical aspect for a successful implant-supported restoration is the passive and an accurate fit of superstructures to avoid preload and loading stresses. Splinting impression technique in multiple implants has gained popularity. Auto-polymerizing acrylic resin is among the most routinely practiced splinting material for multiple implant units. However, unfortunately, it exhibits shrinkage, which makes an impression quite inaccurate. This case report presents the solution to minimize the shrinkage of resin by utilizing sectional-splinting technique as advocated in the previous implant literature. PMID:24963251

  3. Impression technique for the assessment of oedema: comparison with a new tactile sensor that measures physical properties of tissue

    Microsoft Academic Search

    O. A. Lindahl; S. Omata

    1995-01-01

    To measure tissue oedema, the impression technique and a new tactile sensor technique are compared and evaluated in a silicone\\u000a rubber model and in an in vivo rat testis model. The principles of the two techniques differ in that the impression technique\\u000a evaluates interstitial fluid flow FT and peak force F(0) when tissue is compressed, whereas the tactile sensor evaluates

  4. A Comparison of Stainless Steel Hand and Rotary Nickel-Titanium Instrumentation Using a Silicone Impression Technique

    Microsoft Academic Search

    JL Chen; HH Messer

    2002-01-01

    Background: Root canal preparation using rotary nickel-titanium instruments has been reported to be superior to hand instrumentation in terms of root canal shape, centring and frequency of procedural errors. The purpose of this study was to evaluate canal preparations using a sequential silicone impression technique to assess root canal morphology. Methods: Pre-operative canal impressions were obtained from 24 extracted single-rooted

  5. An empirical study of audience impressions of B2C web pages in Japan, China and the UK

    Microsoft Academic Search

    Jian Hu; Kazuyuki Shima; Ruediger Oehlmann; Jiamin Zhao; Yasuhiro Takemura; Ken-ichi Matsumoto

    2004-01-01

    Negative impressions that arise during a first interaction with a Business-to-Customer web page often have the unpleasant side effect to destroy a firm's efforts in achieving B2C electronic commerce on the WWW. This paper verifies the relation between audience impressions and the visual style of a B2C web page. In comparison to previous work, the experimental procedure was greatly improved.

  6. Effect of Different Disinfectants on Staphylococcus aureus and Candida albicans Transferred to Alginate and Polyvinylsiloxane Impression Materials

    PubMed Central

    Parnia, Fereydun; Hafezeqoran, Ali; Moslehifard, Elnaz; Mahboub, Farhang; Nahaei, Mohammadreza; Akbari Dibavar, Mohammad

    2009-01-01

    Background and aims Several products have been marketed for disinfecting impression materials. The present study evaluated the effect of Deconex, Micro 10, Alprocid and Unisepta Plus sprays on Staphylococcus aureus and Candida albicans transferred to alginate and polyvinylsiloxane impression materials. Materials and methods A total of 180 impressions of a maxillary model (90 alginate and 90 polyvinylsiloxane im-pressions) were taken for the purpose of this in vitro study. Half of the impressions were infected with Staphylococcus au-reus and the other half were infected with Candida albicans. Then the microorganisms were cultured and their counts were determined. Subsequently, the impressions were divided into groups of 15 impressions each. Each group was disinfected with Deconex, Micro10, Alprocid and Unisepta Plus according to manufacturers' instructions except for the control group. The culturing procedure was repeated after disinfection and microbial counts were determined again. Data was analyzed by ANOVA and paired-sample t-test. Results There were statistically significant differences in the means of S. aureus and C. albicans counts before and after the use of disinfectants (P < 0.05). The use of the four disinfectants reduced S. aureus counts to zero in 80% of the cases. There were no statistically significant differences in S. aureus count reductions between the four disinfectants evaluated (P = 0.31). Micro 10 was more effective on alginate; Deconex was more efficient for polyvinylsiloxane and Alprocid had a better efficacy in both impression materials in eliminating C. albicans (P < 0.05). Conclusion All the disinfectants evaluated have high disinfecting postentials. PMID:23230499

  7. Maleimide Functionalized Siloxane Resins

    SciTech Connect

    Loy, D.A.; Shaltout, R.M.

    1999-04-01

    Polyorganosiloxanes are a commercially important class of compounds. They exhibit many important properties, including very low glass transition temperatures, making them useful over a wide temperature range. In practice, the polysiloxane polymer is often mixed with a filler material to help improve its mechanical properties. An alternative method for increasing polymer mechanical strength is through the incorporation of certain substituents on the polymer backbone. Hard substituents such as carbonates and imides generally result in improved mechanical properties of polysiloxanes. In this paper, we present the preparation of novel polysiloxane resins modified with hard maleimide substituents. Protected ethoxysilyl-substituted propyl-maleimides were prepared. The maleimide substituent was protected with a furanyl group and the monomer polymerized under aqueous acidic conditions. At elevated temperatures (>120 C), the polymer undergoes retro Diels-Alder reaction with release of foran (Equation 1). The deprotected polymer can then be selectively crosslinked by a forward Diels-Alder reaction (in the presence of a co-reactant having two or more dime functionalities).

  8. Crosslinking of siloxane elastomers

    Microsoft Academic Search

    Jacob Heiner; Bengt Stenberg; Maria Persson

    2003-01-01

    Silicones are widely used where elastomers come in contact with food and pharmaceuticals. Different curing methods can be applied for crosslinking this elastomer. Ageing tests clearly show that peroxide-cured silicone elastomers should be avoided in view of the fact that post-curing occurs if they are sterilized. This will result in a change in properties over time. Dicumyl peroxide is frequently

  9. METAL COMPLEXING SILOXANE POLYMERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel silicone polymers containing pendant phosphonate groups have been synthesized. A new silicone monomer, (CH3O)2CH3Si(CH2)3P=O(OCH2CH3)2 has been copolymerized with dimethyldimethoxysilane to form polymers capable of binding metal salts. The viscous liquids can complex a variety of metals, inc...

  10. Thermally stimulated transformation of the structure of cobalt complexes in polyvinyl alcohol-cobalt(II) chloride systems

    Microsoft Academic Search

    A. S. Stukalova; I. Yu. Prosanov

    2007-01-01

    We present the kinetic and temperature dependences of the optical absorption of thermochromic films of polyvinyl alcohol with\\u000a added CoCl2. Based on the data obtained, we have analyzed the possibility that tetrahedral cobalt complexes are formed from octahedral\\u000a complexes.

  11. Thermally stimulated transformation of the structure of cobalt complexes in polyvinyl alcohol-cobalt(II) chloride systems

    Microsoft Academic Search

    A. S. Stukalova; I. Yu. Prosanov

    2007-01-01

    We present the kinetic and temperature dependences of the optical absorption of thermochromic films of polyvinyl alcohol with added CoCl2. Based on the data obtained, we have analyzed the possibility that tetrahedral cobalt complexes are formed from octahedral complexes.

  12. Characterization of estrogenic compounds in medical polyvinyl chloride tubing by gas chromatography–mass spectrometry and estrogen receptor binding assay

    Microsoft Academic Search

    Koichi Inoue; Hiroyo Okumura; Tae Higuchi; Hisao Oka; Yoshihiro Yoshimura; Hiroyuki Nakazawa

    2002-01-01

    Background: In 2001, the U.S. Food and Drug Administration (FDA) convened to conduct a safety assessment of a plasticizer, di(2-ethylhexyl) phthalate (DEHP), released from polyvinyl chloride (PVC) medical devices. Hospitalized patients may be exposed to high concentrations of plasticizers, antioxidants, and chemical contaminants in PVC medical devices during blood transfusion or hemodialysis, thus, making them vulnerable to more potentially adverse

  13. Investigations on the intrinsic viscosity of poly(vinyl chloride)(PVC) affected by polymer–polymer interactions in solution

    Microsoft Academic Search

    Yang Haiyang; Zhu Pingping; Li Guofeng; Wu Peng; Ren Feng

    1999-01-01

    The concentration-dependent intermolecular interactions between poly(vinyl chloride) (PVC) and various polymers selected to form polymer solvent were thoroughly investigated by the method of polymer solvent. It has been found that these interactions depended upon both the polymer selected to form the polymer solvent and the concentration of the selected polymer in polymer solvent. If polystyrene (PS), an incompatible polymer with

  14. Study of enzymatic degradation and water absorption of nanocomposites starch\\/polyvinyl alcohol and sodium montmorillonite clay

    Microsoft Academic Search

    Mohammad Taghi Taghizadeh; Zahra Abbasi; Zainab Nasrollahzade

    The aims of the study were to investigate the effect of polyvinyl alcohol (PVA) and sodium montmorillonite clay content within the thermoplastic starch (TPS) blends on the rate and extent of starch enzymatic hydrolysis using enzyme -amylase. The results of this study have revealed that blends with a MMT-Na content at 5wt% exhibited a significantly reduced rate and extent of

  15. Poly(vinyl alcohol)–collagen hydrolysate thermoplastic blends: II. Water penetration and biodegradability of melt extruded films

    Microsoft Academic Search

    P. Alexy; D. Bakoš; G. Crko?ová; Z. Kramárová; J. Hoffmann; M. Julinová; E. Chiellini; P. Cinelli

    2003-01-01

    Water solubility of polyvinyl alcohol (PVA) is related to degree of hydrolysis, molecular weight and modification during blending in the presence of other processing additives. In the present paper the effect of collagen hydrolysate (CH), an abundant waste product of the leather industry, and glycerol on PVA water sensitivity has been investigated. This study is a continuation of the previous

  16. Creep behaviour of ?-phase of U-Zr system by impression creep technique

    NASA Astrophysics Data System (ADS)

    Kutty, T. R. G.; Basak, C. B.; Kumar, Arun; Kamath, H. S.

    2011-01-01

    In this study, the impression creep behaviour of ?-phase of U-50 wt.% Zr (U-72.29 at.% Zr) system was studied in the temperature range 525-575 °C at different stresses. The velocity of the punch at different stresses and temperatures were evaluated for the above alloy. The stress exponents and thermal activation parameters of the above alloy were determined. A power law behaviour is displayed with the stress exponents range from 6.5 to 7. The activation enthalpy for the ?-UZr 2 was found to be independent of stress with an average value of 106 kJ/mol.

  17. First impression versus extended usage: a comparison of product testing methodologies for perfume.

    PubMed

    Shalofsky, I

    1993-04-01

    Synopsis In the fine fragrance industry, unlike many other fast moving consumer goods (fmcg) industries, systematic consumer product-testing has usually been conspicuous by its absence. The reasons are varied, including perfume's own traditions rooted in fashion rather than in marketing, the reluctance of perfumers to see their creations tested, the frequently (and perhaps, surprisingly) short lead times accorded for new product development and, of course, costs. When consumer product-testing is carried out, it is often limited for these same reasons, to 'sniff-testing', which, in the perfume industry, is equivalent to 'first impression' testing. This paper suggests that such sniff-testing may not only be unreliable, but perhaps more unreliable for the perfume category than has been realized hitherto. Reference is made to two consumer research studies on perfume, a qualitative project in France, followed by a quantitative exercise in the UK. A comparison is made between in-home test and sniff-test results for the same set of perfumes, which illustrates the limitations of sniff-testing in general, and the misleading results that it may produce, in particular. A major implication is that perfume is one product category which should be tested in extended usage, and not just for 'first impressions'. Résumé Dans l'industrie de la parfumerie fine, contrairement aux autres industries de produits de grande consommation, les tests consommateurs systématiques sont rarement utilisés. Les raisons sont diverses; les traditions propres du parfum tournées vers la mode plutôt que vers le marketing, le refus des parfumeurs de voir leurs créations subir des tests, les délais étonnamment courts pour le développement d'un nouveau produit et, bien sûr, le coût. Lorsqu'un test consommateurs est effectué, il se résume généralement pour ces mêmes raisons, en un test 'sniff', ce qui, dans l'industrie du parfum équivaut à un test de 'première impression'. Cet article montre que ces tests 'sniff' sont encore moins fiables pour le parfum que l'on avait pensé jusqu'à maintenant. Il est fait référence à deux tests consommateurs sur le parfum, un projet qualitatif en France, suivi par un exercice quantitatif effectué en Grande Bretagne. La comparaison entre les tests réalisés à domicile d'une part, et en sale d'autre part, montre que, pour les mêmes parfums, les résultats obtenus peuvent être erronés. Une des conclusions principales est que le parfum est un produit qui devrait être testé sur une longue période et non pas sur une première impression. PMID:19272121

  18. Amelanotic corneally displaced malignant conjunctival melanoma: a case report evaluated with impression cytology.

    PubMed

    Barros, Jeison de Nadai; Motono, Márcia; Costa, Felipe D'Almeida; Cunha, Marcelo Carvalho da; Chojniak, Martha Motono

    2014-01-01

    Here we describe the case of a 65-year-old Caucasian female who presented with an amelanotic malignant conjunctival melanoma and highlight the clinical and pathological features of this rare entity that displayed exclusive corneal invasive growth without evidence of conjunctival tumors other than primary acquired melanosis. Impression cytology aided in the initial diagnosis. The patient underwent surgical treatment. Histopathology and immunohistochemistry revealed an invasive amelanotic melanoma limited to the cornea and exhibiting S-100, Melan A, and HMB-45 positivity. The absence of pigmentation delayed early clinical detection and treatment. Awareness of this nonpigmented melanoma is important for early recognition and appropriate management. PMID:25076376

  19. Immunopathological findings in conjunctival cells using immunofluorescence staining of impression cytology specimens.

    PubMed Central

    Baudouin, C; Haouat, N; Brignole, F; Bayle, J; Gastaud, P

    1992-01-01

    The conventional technique of impression cytology provides a non-invasive method for the evaluation of conjunctival epithelium alterations. Using indirect immunofluorescence procedures two inflammatory markers, class II MHC antigens HLA DR and the receptor to IgE (CD23), were sought in impression cytology specimens obtained from 80 patients. In normal subjects conjunctival epithelial cells did not show any reactivity. Only scattered dendritic cells were found to express class II antigens but not the receptor to IgE. In contrast patients with chronic conjunctivitis of various aetiologies, mainly infectious or allergic, had 40-100% of brightly positive conjunctival cells for one or both antigens. In these cases epithelial cells and goblet cells reacted similarly. Twenty four eyes in 12 patients with idiopathic dry eye syndrome disclosed results similar to those from normal conjunctival specimens. However 18 other specimens from patients suffering from idiopathic tear deficiency but undergoing multiple substitutive treatments for dry eye had moderate to strong positivity for HLA DR and/or the receptor to IgE (20-100% of cells). As these results were independent of the degree of squamous metaplasia the expression of these membrane markers may reflect local inflammation in addition to tear deficiency, possibly due to sensitisation to the eye drops used. These immunocytological techniques thus provide useful methods of investigating conjunctival inflammation and allergy. They may constitute valuable aid in the diagnosis and appropriate treatment of ocular surface disorders. Images PMID:1420060

  20. Spectral enhancement of leucocrystal violet treated footwear impression evidence in blood.

    PubMed

    Spence, Lindsay; Asmussen, Gary

    2003-03-27

    The results presented demonstrate the capacity for spectral enhancement to substantially improve the forensic examination of footwear impressions in blood treated with leucocrystal violet (LCV). The UV-Vis absorption spectra were generated of (i) an aqueous solution of leucocrystal violet, (ii) leucocrystal violet in 3% H(2)O(2), (iii) LCV working solution and (iv) whole blood added to LCV working solution. The resultant fluorescence emission spectra were subsequently generated (lambda(ex)=630nm, lambda(em)=661-900nm). The results indicate that the UV-Vis absorption spectra of an unbuffered solution of whole blood with LCV working solution produces a strong absorbance curve with a maxima at 630nm. Subsequent excitation at this wavelength and generation of the emission spectrum in the fluorescence mode indicates that a solution of whole blood added to LCV working solution is an extremely weak fluorophore. Therefore, to enable an adequate and timely enhancement of blood impression evidence treated with LCV utilising either visible fluorescence or infrared luminescence requires (i) selection of the most appropriate excitation wavelength (lambda(ex)) and emission wavelength (lambda(em)) with extremely narrow band pass filters, which in the absence of substrate matrix interference is excitation at 630nm producing the emission maxima at 665nm and (ii) a visual enhancement system such as a CCD colour IR video camera with image integration. PMID:12711191