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Sample records for polyvinyl siloxane impression

  1. The dimensional accuracy of polyvinyl siloxane impression materials using two different impression techniques: An in vitro study

    PubMed Central

    Kumari, Nirmala; Nandeeshwar, D. B.

    2015-01-01

    Aim of the Study: To evaluate and compare the linear dimensional changes of the three representative polyvinyl siloxane (PVS) impression materials and to compare the accuracy of single mix with double mix impression technique. Methodology: A study mold was prepared according to revised American Dental Association specification number 19 for nonaqueous elastic dental impression materials. Three PVS impression materials selected were Elite-HD, Imprint™ II Garant, Aquasil Ultra Heavy. Two impression techniques used were single mix and double mix impression technique. A total of 60 specimens were made and after 24 h the specimens were measured using profile projector. Statistical Analysis: The data were analyzed using one-way analyses of variance analysis and significant differences were separated using Student's Newman–Keul's test. Results: When all the three study group impression materials were compared for double mix technique, the statistically significant difference was found only between Imprint™ II Garantand Elite-HD (P < 0.05). Similarly, using single mix technique, statistically significant difference were found between Elite-HD and Imprint™ II Garant (P < 0.05) and also between Aquasil Ultra Heavy and Elite-HD (P < 0.05). When the linear dimensional accuracy of all three impression material in double mix impression technique and single mix impression technique were compared with the control group, Imprint™ II Garant showed the values more nearing to the values of master die, followed by Aquasil Ultra Heavy and Elite-HD respectively. Conclusion: Among the impression materials Imprint™ II Garant showed least dimensional change. Among the impression techniques, double mix impression technique showed the better results. PMID:26929515

  2. Comparative evaluation of dimensional accuracy of different polyvinyl siloxane putty-wash impression techniques-in vitro study.

    PubMed Central

    Dugal, Ramandeep; Railkar, Bhargavi; Musani, Smita

    2013-01-01

    Background: Dimensional accuracy when making impressions is crucial to the quality of fixed prosthodontic treatment, and the impression technique is a critical factor affecting this accuracy. The purpose of this in vitro study was to compare the dimensional accuracy of the casts obtained from one step double mix, two step double mix polyvinyl siloxane putty- wash impression techniques using three different spacer thicknesses (0.5mm, 1mm and 1.5mm), in order to determine the impression technique that displays the maximum linear dimensional accuracy. Materials & Methods: A Mild steel model with 2 abutment preparations was fabricated, and impressions were made 15 times with each technique. All impressions were made with an addition-reaction silicone impression material (Express, 3M ESPE) and customarily made perforated metal trays. The 1-step putty/light-body impressions were made with simultaneous use of putty and light-body materials. The 2-step putty/light-body impressions were made with 0.5-mm, 1mm and 1.5mm-thick metal-prefabricated spacer caps. The accuracy of the 4 different impression techniques was assessed by measuring 7 dimensions (intra- and inter abutment) (20-μm accuracy) on stone casts poured from the impressions of the mild steel model. The data were analyzed by one sample‘t’ test. Results: The stone dies obtained with all the techniques had significantly larger or smaller dimensions as compared to those of the mild steel model (P<0.05). The order for highest to lowest deviation from the mild steel model was: single step putty/light body, 2-step putty/light body with 0.5mm spacer thickness, 2-step putty/light body1.5mm spacer thickness, and 2-step putty/light body with 1mm spacer thickness. Significant differences among all of the groups for both absolute dimensions of the stone dies, and their standard deviations from the master model (P<0.05), were noted. Conclusions: The 2-step putty/light-body impression technique with 1mm spacer thickness was

  3. Evaluation of surface detail reproduction, dimensional stability and gypsum compatibility of monophase polyvinyl-siloxane and polyether elastomeric impression materials under dry and moist conditions

    PubMed Central

    Vadapalli, Sriharsha Babu; Atluri, Kaleswararao; Putcha, Madhu Sudhan; Kondreddi, Sirisha; Kumar, N. Suman; Tadi, Durga Prasad

    2016-01-01

    Objectives: This in vitro study was designed to compare polyvinyl-siloxane (PVS) monophase and polyether (PE) monophase materials under dry and moist conditions for properties such as surface detail reproduction, dimensional stability, and gypsum compatibility. Materials and Methods: Surface detail reproduction was evaluated using two criteria. Dimensional stability was evaluated according to American Dental Association (ADA) specification no. 19. Gypsum compatibility was assessed by two criteria. All the samples were evaluated, and the data obtained were analyzed by a two-way analysis of variance (ANOVA) and Pearson's Chi-square tests. Results: When surface detail reproduction was evaluated with modification of ADA specification no. 19, both the groups under the two conditions showed no significant difference statistically. When evaluated macroscopically both the groups showed statistically significant difference. Results for dimensional stability showed that the deviation from standard was significant among the two groups, where Aquasil group showed significantly more deviation compared to Impregum group (P < 0.001). Two conditions also showed significant difference, with moist conditions showing significantly more deviation compared to dry condition (P < 0.001). The results of gypsum compatibility when evaluated with modification of ADA specification no. 19 and by giving grades to the casts for both the groups and under two conditions showed no significant difference statistically. Conclusion: Regarding dimensional stability, both impregum and aquasil performed better in dry condition than in moist; impregum performed better than aquasil in both the conditions. When tested for surface detail reproduction according to ADA specification, under dry and moist conditions both of them performed almost equally. When tested according to macroscopic evaluation, impregum and aquasil performed significantly better in dry condition compared to moist condition. In dry

  4. Effects of sulfur-based hemostatic agents and gingival retraction cords handled with latex gloves on the polymerization of polyvinyl siloxane impression materials

    PubMed Central

    MACHADO, Carlos Eduardo Palhares; GUEDES, Carlos Gramani

    2011-01-01

    Objectives This study investigated the possible interactions between three addition silicone materials (Express®, Aquasil Ultra® and Adsil®), three hemostatic agents (ferric sulfate, StatGel FS®; aluminum sulfate, GelCord®; and aluminum chloride, Hemostop®) and gingival retraction cords previously handled with latex gloves to determine whether direct contact with medicaments or indirect contamination by latex in conditions similar to those found in clinical practice inhibit or affect the setting of the impression materials. Material and Methods A portable device for the simultaneous test of several specimens was specifically developed for this study. Polymerization inhibition was analyzed by examination of the impressions and the molded surface. Ten trials were performed for each addition silicone material used in the study, at a total of 240 study samples. Results All the samples tested (N=240) were nonreactive regardless of the type of combination used. Conclusions Aluminum sulfate, ferric sulfate and aluminum chloride hemostatic solutions did not show any inhibitory potential on the addition silicone samples under study, and there were no changes in polymerization as a result of contact between addition silicone and retraction cords handled with latex gloves. PMID:22230998

  5. Polyvinyl siloxane: novel material for external nasal splinting.

    PubMed

    Jayakumar, N K; Rathnaprabhu, V; Ramesh, S; Parameswaran, A

    2016-01-01

    External nasal splinting is performed routinely after nasal bone fracture reductions, osteotomies, and rhinoplasties. Materials commonly used include plaster of Paris (POP), thermoplastic splints, self-adhesive padded aluminium splints, and Orthoplast, among many others. The disadvantages of these materials are described in this paper, and polyvinyl siloxane is recommended as an effective and more readily available alternative material to counter these pitfalls. PMID:26454773

  6. Wettability of nonaqueous elastomeric impression materials.

    PubMed

    Chai, J Y; Yeung, T C

    1991-01-01

    The wettability of eight nonaqueous elastomeric impression materials was studied by comparing their contact angles. The materials included three polyethers (one of which was light activated), three hydrophilic poly(vinyl siloxanes), one conventional poly(vinyl siloxane), and one poly(vinyl siloxane) putty. Extracted teeth were prepared to approximate the roughness of a tooth preparation. Contact angles were measured at different time intervals after the start of mixing but were not shown to be significant. The nonhydrophilic poly(vinyl siloxane) materials and the poly(vinyl siloxane) putty were found to be significantly less wettable. PMID:1817528

  7. “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

  8. 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

  9. A Technique to Transfer the Emergence Profile Contours of a Provisional Implant Crown to the Definitive Impression.

    PubMed

    Shah, Karnik; Yilmaz, Burak

    2016-01-01

    This clinical report describes a method to create a proper emergence profile and accurately transfer it to the definitive impression, using an indirectly fabricated modified impression post. A provisional screwretained crown was indexed with a polyvinyl siloxane material. An autopolymerizing acrylic resin was used to modify an impression post on the polyvinyl siloxane index, which was then screwed onto the implant for the definitive impression after proper soft tissue healing. The indirectly fabricated modified impression post helped to transfer the contours to the definitive impression with minimal soft tissue irritation. PMID:27004296

  10. Effect of surfactant on surface hardness of dental stone and investment casts produced from polyvinyl siloxane duplicating materials.

    PubMed

    Al-Johani, Attalah; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2008-06-01

    Polyvinylsiloxane duplicating materials are typically treated with a topical surfactant before pouring dental models, but the use of topical surfactants in the dental laboratory may affect the surface hardness of the resultant models. The effect of two different topical surfactants on surface hardness of two dental stones (FujiRock and Dentstone) and one phosphate bonded investment material (Croform WB) produced from polyvinyl siloxane (PVS) dental laboratory duplicating moulds was investigated. Topical surfactants affected the surface hardness of FujiRock, Dentstone and Croform WB investment material. Surface hardness of FujiRock increased with Wax-Mate surfactant. However, surface hardness of Croform WB investment material decreased with both topical surfactants. PMID:18637383

  11. Evaluation of dimensional stability of autoclavable elastomeric impression material.

    PubMed

    Surendra, G P; Anjum, Ayesha; Satish Babu, C L; Shetty, Shilpa

    2011-03-01

    Impressions are important sources of cross contamination between patients and dental laboratories. As a part of infection control impressions contaminated with variety of micro-organisms via blood and oral secretions should be cleaned and disinfected or sterilized before being handled in dental laboratory. The purpose of this study was to determine the effect of autoclaving on dimensional stability of elastomeric impression material (polyvinyl siloxane-Affinis). In this in vitro study standardized stainless steel die as per ADA specification number 19 was fabricated. Polyvinyl siloxane (Affinis) light body and putty viscosity elastomeric impression materials were used. A total of 40 impressions of the stainless steel die were made and numeric coding system was used to identify the samples. Measurements were made using a measuring microscope. Distance between the cross lines CD and C'D' reproduced in the impression were measured before autoclaving, immediately after autoclaving and 24 hours after autoclaving and dimensional change was calculated. The data obtained was subjected to statistical analysis. The mean difference in dimensional change between the three groups was not statistically significant (P > 0.05). However the results revealed that there was higher mean dimensional change immediately after autoclaving when compared to the other 2 time intervals. It is desirable to delay the casting of an autoclavable elastomeric impression material by about 24 hours. Though disinfection of impression is routinely followed autoclaving of impression is an effective method of sterilization. PMID:22379308

  12. An innovative impression technique for fabrication of a custom made ocular prosthesis

    PubMed Central

    Tripuraneni, Sunil Chandra; Vadapalli, Sriharsha Babu; Ravikiran, P; Nirupama, N

    2015-01-01

    Various impression and fitting techniques have been described in the past for restoring ocular defects. The present article describes a new direct impression technique for recording and rehabilitating ocular defects, by custom-made ocular prosthesis. All the techniques described in the history, mainly concentrated in recording the tissue surface of the defect, which made it difficult to contour the palpebral surface resulting in the poor esthetics of the prosthesis. The present impression technique uses heavy bodied polyvinyl siloxane impression material, which facilitates accurate recording of the tissue surface and the palpebral surface of the defect, resulting in the fabrication of functionally and esthetically acceptable prosthesis. PMID:26265651

  13. Hydrophilicity of unset and set elastomeric impression materials.

    PubMed

    Rupp, Frank; Geis-Gerstorfer, Jurgen

    2010-01-01

    The aim of this study was to compare the initial hydrophilicity of unset and set elastomeric impression materials. Initial water contact angles were studied on thin unset and set films of one polyether and six polyvinyl siloxane (PVS) impression materials using high-resolution drop shape analysis at drop ages of 1 and 3 seconds. All unset PVS materials were very hydrophobic initially but showed different kinetics of hydrophilization. In contrast, the unset polyether was more hydrophilic initially but lacked distinct hydrophilization. All impression materials showed statistically significant contact angle differences between unset and set surfaces (P < .05). Dependent on the drop age, two PVS materials reached or exceeded the hydrophilicity of the polyether (P < .05). It can be concluded that studies on the wetting behavior of elastomeric impression materials should consider both the experimental drop age and set and unset material surfaces. PMID:21209992

  14. Effect of different impression materials and techniques on the dimensional accuracy of implant definitive casts

    PubMed Central

    Ebadian, Behnaz; Rismanchian, Mansor; Dastgheib, Badrosadat; Bajoghli, Farshad

    2015-01-01

    Background: Different factors such as impression techniques and materials can affect the passive fit between the superstructure and implant. The aim of this study was to determine the effect of different impression materials and techniques on the dimensional accuracy of implant definitive casts. Materials and Methods: Four internal hex implants (Biohorizons Ø4 mm) were placed on a metal maxillary model perpendicular to the horizontal plane in maxillary lateral incisors, right canine and left first premolar areas. Three impression techniques including open tray, closed tray using ball top screw abutments and closed tray using short impression copings and two impression materials (polyether and polyvinyl siloxane) were evaluated (n = 60). The changes in distances between implant analogues in mediolateral (x) and anteroposterior (y) directions and analogue angles in x/z and y/z directions in the horizontal plane on the definitive casts were measured by coordinate measuring machine. The data were analyzed by multivariate two-way analysis of variance and one sample t-test (α = 0.05). Results: No statistical significant differences were observed between different impression techniques and materials. However, deviation and distortion of definitive casts had a significant difference with the master model when short impression copings and polyvinyl siloxane impression material were used (P < 0.05). In open tray technique, there was a significant difference in the rotation of analogs compared with the master model with both impression materials (P < 0.05). Conclusion: There was no difference between open and closed tray impression techniques; however, less distortion and deviation were observed in the open tray technique. In the closed tray impression technique, ball top screw was more accurate than short impression copings. PMID:25878678

  15. Effect of disinfection of custom tray materials on adhesive properties of several impression material systems.

    PubMed

    Thompson, G A; Vermilyea, S G; Agar, J R

    1994-12-01

    The effects of impression tray disinfection procedures on the bond strength of impression-material adhesives to two types of resin trays were evaluated with a tensile test. Autopolymerizing acrylic resin and a visible light-curing resin were formed into one-half inch cubes. A screw eye was attached to each cube before polymerization. Perforated trays were fabricated with stops to maintain an even one-eighth inch of impression material over the resin block. Hooks on the opposite side permitted attachment of the metal plate to a mechanical testing machine. Before adhesive was applied, one third of the resin specimens were immersed in a 1:213 iodophor solution; one third in a 10% sodium hypochlorite solution, and one third were kept in the "as fabricated" condition. Polysulfide, polyether, and polyvinyl siloxane impression material-adhesive systems were evaluated. The resin-impression material-metal plate couples were attached to a mechanical testing machine and tensile forces were applied at a separation rate of 5 inches per minute. Mean values for adhesive strength ranged from 3.49 kg/cm2 for the autopolymerizing acrylic resin/iodophor/polyether combination to 10.55 kg/cm2 for the autopolymerizing acrylic resin/untreated/polyvinyl siloxane combination. Differences were detected among materials and disinfecting procedure. Clinically, disinfection of resin trays may adversely affect retention of the impression material to the tray. PMID:7853264

  16. An Investigation into the Accuracy of Two Currently Available Dental Impression Materials in the Construction of Cobalt-Chromium Frameworks for Removable Partial Dentures.

    PubMed

    Dubal, Rajesh Kumar; Friel, Tim; Taylor, Philip D

    2015-03-01

    This study investigated the suitability of irreversible hydrocolloid as an impression material for cobalt-chromium framework construction. Scans of casts derived from (1) alginate and (2) addition-cured polyvinylsiloxane impressions were superposed on to a control. The differences within and between groups were compared at fixed landmarks. The investigation revealed a high degree of scan coincidence within and between groups. However, certain features, such as undercuts, resulted in a lower degree of scan coincidence. Irreversible hydrocolloid appears to be a viable alternative to addition-cured polyvinyl-siloxane as an impression material for cobalt-chromium framework construction. PMID:26415334

  17. Effect of the impression margin thickness on the linear accuracy of impression and stone dies: an in vitro study.

    PubMed

    Naveen, Y G; Patil, Raghunath

    2013-03-01

    The space available for impression material in gingival sulcus immediately after the removal of retraction cord has been found to be 0.3-0.4 mm. However after 40 s only 0.2 mm of the retracted space is available. This is of concern when impression of multiple abutments is to be made. Hence a study was planned to determine the minimum width of the retracted sulcus necessary to obtain a good impression. Five metal dies were machined to accurately fit a stainless steel block with a square cavity in the center with spaces, 1 mm deep and of varying widths (0.11-0.3 mm) away from the block. Polyvinyl siloxane impressions were made and poured using a high strength stone. Using traveling microscope, length and widths of abutment, impression and die were measured and compared for linear accuracy and completeness of impression. Results showed 1.5-3 times greater mean distortion and larger coefficient of variance in the 0.11 mm group than in the wider sulcular groups. ANOVA test for distortion also showed statistically significant differences (P < 0.05). 75 % of impressions in 0.11 mm group were defective compared to less than 25 % of impressions in other width groups. It is not always possible to predictably obtain accurate impressions in sulcus width of 0.11 mm or lesser. Dimensionally accurate and defect free impressions were obtained in sulcus width of 0.15 mm and wider. Hence clinicians must choose retraction methods to obtain a width greater than 0.35 mm. Further immediate loading of the impression material after cord removal may improve accuracy. PMID:24431701

  18. Accuracy of different impression materials in parallel and nonparallel implants

    PubMed Central

    Vojdani, Mahroo; Torabi, Kianoosh; Ansarifard, Elham

    2015-01-01

    Background: A precise impression is mandatory to obtain passive fit in implant-supported prostheses. The aim of this study was to compare the accuracy of three impression materials in both parallel and nonparallel implant positions. Materials and Methods: In this experimental study, two partial dentate maxillary acrylic models with four implant analogues in canines and lateral incisors areas were used. One model was simulating the parallel condition and the other nonparallel one, in which implants were tilted 30° bucally and 20° in either mesial or distal directions. Thirty stone casts were made from each model using polyether (Impregum), additional silicone (Monopren) and vinyl siloxanether (Identium), with open tray technique. The distortion values in three-dimensions (X, Y and Z-axis) were measured by coordinate measuring machine. Two-way analysis of variance (ANOVA), one-way ANOVA and Tukey tests were used for data analysis (α = 0.05). Results: Under parallel condition, all the materials showed comparable, accurate casts (P = 0.74). In the presence of angulated implants, while Monopren showed more accurate results compared to Impregum (P = 0.01), Identium yielded almost similar results to those produced by Impregum (P = 0.27) and Monopren (P = 0.26). Conclusion: Within the limitations of this study, in parallel conditions, the type of impression material cannot affect the accuracy of the implant impressions; however, in nonparallel conditions, polyvinyl siloxane is shown to be a better choice, followed by vinyl siloxanether and polyether respectively. PMID:26288620

  19. Impression materials in fixed prosthodontics: influence of choice on clinical procedure.

    PubMed

    Hamalian, Techkouhie A; Nasr, Elie; Chidiac, José J

    2011-02-01

    The purpose of this article is to review impression materials used for fabricating fixed restorations in dentistry. Their compositions, properties, advantages, and disadvantages are presented and compared. How these properties influence clinical decisions is also described. This review helps the clinician choose which material is more suitable for a specific case. A broad search of the published literature was performed using Medline to identify pertinent current articles. Textbooks, the Internet, and manufacturers' literature were also used to supplement this information. It is limited to impression materials used in fixed prosthodontics. The review gives basic knowledge of ideal impression material properties and discusses traditional and, primarily, more recently developed products, such as polyethers, poly(vinyl siloxane), polysulfides, and condensation silicone materials. Clear advantages and disadvantages for these impression materials are provided along with the role that compositional variations have on the outcome of the impression. This should enable clinicians and technicians to easily identify the important physical properties of each type of impression material and their primary clinical indications. PMID:21284760

  20. 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 μm; squared impression copings with no splint: 205.86 μm; splinted squared impression copings: 99.19 μm. 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

  1. 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.

  2. 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.

  3. Oligosilane-siloxane nanocomposites

    SciTech Connect

    Loy, D.A.; Jamison, G.M.; Waymouth, R.M.; Opperman, K.A.; Beach, J.V.

    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.

  4. Siloxane-modified polyethersulfideimide

    NASA Technical Reports Server (NTRS)

    Burks, Harold D.; St. Clair, Terry L.

    1987-01-01

    BDSDA/APB, a novel linear polyethersulfideimide, was synthesized using siloxane units as flexible linkages in the backbone in an attempt to improve use properties and processability. The effect of these flexible linkages on molecular weight buildup, flexural strength and modulus, glass transition temperature, and melt-flow properties was determined.

  5. Accuracy of Implant Position Transfer and Surface Detail Reproduction with Different Impression Materials and Techniques

    PubMed Central

    Alikhasi, Marzieh; Siadat, Hakimeh; Kharazifard, Mohammad Javad

    2015-01-01

    Objectives: The purpose of this study was to compare the accuracy of implant position transfer and surface detail reproduction using two impression techniques and materials. Materials and Methods: A metal model with two implants and three grooves of 0.25, 0.50 and 0.75 mm in depth on the flat superior surface of a die was fabricated. Ten regular-body polyether (PE) and 10 regular-body polyvinyl siloxane (PVS) impressions with square and conical transfer copings using open tray and closed tray techniques were made for each group. Impressions were poured with type IV stone, and linear and angular displacements of the replica heads were evaluated using a coordinate measuring machine (CMM). Also, accurate reproduction of the grooves was evaluated by a video measuring machine (VMM). These measurements were compared with the measurements calculated on the reference model that served as control, and the data were analyzed with two-way ANOVA and t-test at P= 0.05. Results: There was less linear displacement for PVS and less angular displacement for PE in closed-tray technique, and less linear displacement for PE in open tray technique (P<0.001). Also, the open tray technique showed less angular displacement with the use of PVS impression material. Detail reproduction accuracy was the same in all the groups (P>0.05). Conclusion: The open tray technique was more accurate using PE, and also both closed tray and open tray techniques had acceptable results with the use of PVS. The choice of impression material and technique made no significant difference in surface detail reproduction. PMID:27252761

  6. Good Impressions.

    ERIC Educational Resources Information Center

    Banks, Geraldine; Pulsifer, Mary

    1986-01-01

    An art activity featuring ballerinas in classic poses and costumes was extended by a visit to an exhibit on Edgar Degas. Hearing impaired students shared their impressions of another traveling exhibit with French students via computers. (CL)

  7. Siloxane-grafted membranes

    DOEpatents

    Friesen, Dwayne T.; Obligin, Alan S.

    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.

  8. 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.

  9. First Impressions.

    ERIC Educational Resources Information Center

    Coen, Frank

    1969-01-01

    The unreliability of first impressions and subjective judgments is the subject of both Jane Austen's "Pride and Prejudice" and Lionel Trilling's "Of This Time, Of That Place"; consequently, the works are worthwhile parallel studies for high school students. Austen, by means of irony and subtle characterization, dramatizes the need for constant…

  10. 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

  11. 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).

  12. 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.

  13. Permeation of substituted silanes and siloxanes through selected gloves and protective clothing.

    PubMed

    Nelson, G O; Priante, S J; Strong, M; Anderson, D; Fallon-Carine, J

    2000-01-01

    Testing of the permeation resistance of eight glove and suit barriers against commercially available substituted silanes and siloxanes was performed using the ASTM F739-96 standard test method. In addition to barrier performance to the pure organosilanes, the permeation rates of the hydrolysis product (usually ethanol or methanol) were investigated. The silanes and siloxanes used as the challenge agents were N-2-(aminoethyl)-3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane; 3-chloropropyltrimethoxysilane; ethyltriacetoxysilane; 3-glycidoxypropyltrimethoxysilane; 1,1,1,3,3,3-hexamethyldisilazane; hexamethyldisiloxane; 3-methacryloxypropyltrimethoxysilane; methyltriacetoxysilane (50%)/ethyltriacetoxysilane (50%); methyltrimethoxysilane; methyltris(methylethylketoxime)silane; phenyltrimethoxysilane; polydimethyl siloxanes (PS 340); octamethylcyclotetrasiloxane (D4); tetraethoxysilane; tetramethoxysilane; 1,1,3,3-tetramethyl disiloxane; triethoxysilane; trimethoxysilane; vinyltrimethoxysilane; and vinyltris(methylethylketoxime)silane. Protective gloves tested were nitrile rubber, neoprene rubber, butyl rubber, 4H laminate, and polyvinyl chloride. Garments tested included Tyvek/Saranex 23P, CPF 2, and Responder, all made by Kappler Safety Group. In all cases the protective suit materials lasted 8 hours or more. The only glove that lasted 8 hours against all chemicals was the 4H laminate. The polyvinyl chloride glove lasted 10 min to 8 hours or more depending on the chemical. The nitrile, neoprene, and butyl rubber gloves lasted from 53 min to 8 hours or more depending on the chemical. The alcohol permeation was similar to the organosilicon compounds. The suit materials and the butyl glove all lasted more than 8 hours for both methanol and ethanol. PMID:11071423

  14. Siloxane containing polyimides with improved processability

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Siloxane containing polyimides were prepared in an effort to improve processability of linear aromatic polyimides and toughness of addition curing imide oligomers. Linear aromatic polyimides were endcapped with varying proportions of a silane; a diaminosiloxane was copolymerized with an aromatic diamine; polyimide oligomers were endcapped with reactive groups; and acetylene terminated siloxane-containing oligomers were blended with linear siloxane-containing polyimides. The resins were used to prepare moldings, titanium to titanium adhesive bonds, and graphite reinforced composites. In each case, physical properties and other characteristics were compared to those of chemically similar polyimides with no siloxane incorporation. The resins, in most cases, performed better at room temperature than the corresponding polyimide. At elevated temperatures, for high siloxane content, the performance deteriorated.

  15. 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...

  16. [Elastomeric impression materials].

    PubMed

    Anagnostopoulos, T; Tsokas, K

    1990-01-01

    A review of the literature on elastomeric impression materials, is presented in this paper. The article mentions the composition and the most important properties of the elastomeric impression materials used in dental practice. The clinical significance of these materials, physical and mechanical properties are also emphasized. In addition some new elastomeric impression materials with improved properties and a new (experimental) light-cured impression material, are mentioned. Another part of this article is the biocompatibility of these materials. In the end the great significance of handling is outlined. PMID:2130039

  17. 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.

  18. ETI: Our first impressions

    NASA Astrophysics Data System (ADS)

    Harrison, Albert A.; Johnson, Joel T.

    2000-06-01

    Despite scant or ambiguous information, people are capable of developing comprehensive and detailed impressions. Consequently, if the detection of an electromagnetically-active civilization is announced, many people will rapidly form impressions of what the extraterrestrials and their civilization are "like". First impressions are crucial, not only because of their immediate psychological, social, and political consequences on Earth, but because they can influence the future of interstellar communication. Initial impressions will rest less on hard data than on the nature and tone of the "evidence" that is gleaned from the transmission; the interpretation and dissemination of this evidence; and the hard wiring, psychological programming, cultural conditioning, and social influence processes that shape human perception. We consider how dispositional inferences, implicit theories of personality, negatively toned or adverse information, physical appearance, prior expectations, the confirmation bias, and thinking and unthinking approaches to attitude formation are likely to affect human impressions of ETI.

  19. 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.

  20. Impression block with orientator

    NASA Astrophysics Data System (ADS)

    Brilin, V. I.; Ulyanova, O. S.

    2015-02-01

    Tool review, namely the impression block, applied to check the shape and size of the top of fish as well as to determine the appropriate tool for fishing operation was realized. For multiple application and obtaining of the impress depth of 3 cm and more, the standard volumetric impression blocks with fix rods are used. However, the registered impress of fish is not oriented in space and the rods during fishing are in the extended position. This leads to rods deformation and sinking due to accidental impacts of impression block over the borehole irregularity and finally results in faulty detection of the top end of fishing object in hole. The impression blocks with copy rods and fixed magnetic needle allow estimating the object configuration and fix the position of magnetic needle determining the position of the top end of object in hole. However, the magnetic needle fixation is realized in staged and the rods are in extended position during fishing operations as well as it is in standard design. The most efficient tool is the impression block with copy rods which directs the examined object in the borehole during readings of magnetic needles data from azimuth plate and averaging of readings. This significantly increases the accuracy of fishing toll direction. The rods during fishing are located in the body and extended only when they reach the top of fishing object.

  1. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  2. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  3. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  4. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  5. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Siloxane modified alumina... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

  6. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  7. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

  8. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  9. 40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Aminofunctional alkoxy alkyl siloxane... Substances § 721.9515 Aminofunctional alkoxy alkyl siloxane. (a) Chemical substance and significant new uses... siloxane (PMN P-96-346) is subject to reporting under this section for the significant new uses...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

  11. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Siloxane modified silica nanoparticles... Specific Chemical Substances § 721.10119 Siloxane modified silica nanoparticles (generic). (a) Chemical... as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxane modified alumina... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

  13. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxane modified alumina... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

  14. Self-assembling particle-siloxane coatings for superhydrophobic concrete.

    PubMed

    Flores-Vivian, Ismael; Hejazi, Vahid; Kozhukhova, Marina I; Nosonovsky, Michael; Sobolev, Konstantin

    2013-12-26

    We report here, for the first time in the literature, a method to synthesize hydrophobic and superhydrophobic concrete. Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (SF) to induce the microroughness and polyvinyl alcohol (PVA) fibers to create hierarchical surfaces. Various emulsion types were investigated by using different mixing procedures, and single- and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical microscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-off angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the effect of surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156° for the specimen with PVA fibers treated with MK based emulsion. Since water penetration is the main factor leading to concrete deterioration, hydrophobic water-repellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering. PMID:24245777

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

    PubMed Central

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

    2016-01-01

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

  16. Evidence for a sedimentary siloxane horizon

    SciTech Connect

    Pellenbarg, R.E.; Tevault, D.E.

    1986-07-01

    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 the horizon directly related to the fact that silicones have been in widespread use only since World War II. All samples were analyzed by solvent extraction and diffuse reflectance Fourier transform infrared spectrometry. 10 references, 2 figures, 1 table.

  17. Copoly(Imide Siloxane) Abhesive Materials with Varied Siloxane Oligomer Length

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Incorporation of PDMS moieties into a polyimide matrix lowered the surface energy resulting in enhanced adhesive interactions. Polyimide siloxane materials were generated using amine-terminated PDMS oligomers of different lengths to study changes in surface migration behavior, phase segregation, mechanical, thermal, and optical properties. These materials were characterized using contact angle goniometry, tensile testing, and differential scanning calorimetry. The surface migration behavior of the PDMS component depended upon the siloxane molecular weight as indicated by distinct relationships between PDMS chain length and advancing water contact angles. Similar correlations were observed for percent elongation values obtained from tensile testing, while the addition of PDMS reduced the modulus. High fidelity topographical modification via laser ablation patterning further reduced the polyimide siloxane surface energy. Initial particulate adhesion testing experiments demonstrated that polyimide siloxane materials exhibited greater abhesive interactions relative to their respective homopolyimides.

  18. [Elastomeric impression materials].

    PubMed

    Levartovsky, S; Folkman, M; Alter, E; Pilo, R

    2011-04-01

    Elastomeric impression materials are in common use. The impression taken should be highly precise, thus, requiring specific care when manipulatingthese materials. There are 4 groups of elastomers; polysulfide, condensation silicone, addition silicone and polyether; each differ in their setting mechanism and their physical and chemical properties. This review elaborates the major properties of elastomers and its implications on their use. The impression material is inserted into the patient's mouth in a viscous state and transforms into viscoelastic state, upon withdrawal, influencing the residual deformation. The requirements are minimal residual deformation or maximal elastic recovery. As the mouth is a wet environment a major consideration is hydrophilicity. The wettability which is estimated by measuring either the contact angle of a droplet of water and the substrate post setting or the contact angle of a droplet of impression material and the wet tooth pre setting, determines the interaction of the material with both mouth fluids and gypsum. As the primary end target is to obtain a model depicting accurately the oral details, an attention to the impressions' compatibility with gypsum should also be given. Many studies were conducted to get a thorough understanding of the hydrophilic properties of each material, and the mechanism utilized, such as surfactants in hydrophilic PVS. Polyether is the only material that is truly hydrophilic; it exhibits the lowest contact angle, during and after setting. Recent studies show that during setting the Polyether hydrophilicity is increased compared to the condition after setting. Dimensional stability, a crucial property of the impression, is affected by the physical and chemical attributes of the material, such as its tear strength. Polysulfide has the highest tear strength. Tear Strength is affected by two major parameters, viscosity, a built-in property, and how fast the impression is pulled out of the mouth, the

  19. 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…

  20. Copoly(imide siloxane) Abhesive Materials with Varied Siloxane Oligomer Length

    NASA Technical Reports Server (NTRS)

    Wohl, Christoper J.; Atkins, Brad M.; Lin, Yi; Belcher, Marcus A.; Connell, John W.

    2010-01-01

    In this work, low surface energy copoly(imide siloxane)s were synthesized with various siloxane segment lengths. Characterization of these materials revealed that domain formation of the low surface energy component within the matrix was more prevalent for longer siloxane segments as indicated by increased opacity, decreased mechanical properties, and variation of the Tg. Incorporation of siloxanes lowered the polymer s surface energy as indicated by water contact angle values. Topographical modification of these materials by laser ablation patterning further reduced the surface energy, even generating superhydrophobic surfaces. Combined, the contact angle data and particle adhesion testing indicated that copoly(imide siloxane) materials may provide greater mitigation to particulate adhesion than polyimide materials alone. These enhanced surface properties for abhesive applications did result in a reduction of the tensile moduli of the copolymers. It is possible that lower siloxane loading levels would result in retention of the mechanical properties of the polyimide while still affording abhesive surface properties. This hypothesis is currently being investigated. Laser ablation patterning offers further reduction in particle retention as the available surface area for particle adhesion is reduced. Pattern variation and size dependencies are currently being evaluated. For the purposes of lunar dust adhesion mitigation, it is likely that this approach, termed passive due to the lack of input from an external energy source, would not be sufficient to mitigate surface contamination or clean contaminated surfaces for some lunar applications. It is feasible to combine these materials with active mitigation strategies - methods that utilize input from external energy sources - would broaden the applicability of such materials for abhesive purposes. Collaborative efforts along these lines have been initiated with researchers at NASA Kennedy Space Center where experiments

  1. 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.

  2. 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.

  3. 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.

  4. Relevance of an organic solvent for absorption of siloxanes.

    PubMed

    Ghorbel, Leila; Tatin, Romuald; Couvert, Annabelle

    2014-01-01

    A wide range of siloxanes exist but the most abundant in biogas are Hexamethyldisiloxane (L2) and Octamethyltrisiloxane (L3) as linear siloxanes and Octamethylcyclotetrasiloxane (D4) as a cyclic siloxane. In order to remove volatile organic compound from biogas, different processes can be used. A promising process for siloxane removal is their absorption in an organic solvent. In this work, three oils were tested to absorb the selected siloxanes: silicone oil 47V20, Seriola 1510 and Polyalphaolefin. Initially, the characterization of these oils was realized by measuring their viscosities and densities, depending on temperature. The second time, the absorption capacity of the siloxanes by selected oils was characterized through the determination of their Henry's constants, but also owing to the implementation of a wet-wall column. Both Henry's constants and removal efficiencies in continuous regime revealed that silicone oil (47V20) can be considered as the most efficient oil among the three selected siloxanes. Moreover, the cyclic siloxane (D4) showed more affinity with oils than linear siloxanes. Silicone oil 47V20 appeared to be the best oil (intermediate price 14 euro/L, low viscosity, low volatility, chemical inertness (no corrosion) and resistance to high and low temperatures). PMID:24600877

  5. Substance Use as Impression Management.

    ERIC Educational Resources Information Center

    Sharp, Mark J.; Getz, J. Greg

    1996-01-01

    Examines the function of substance use as an impression management tactic. Introductory psychology students (n=377) responded to a survey instrument measuring self-monitoring, perceived success in impression management, interaction anxiety, and self-esteem. Results suggest that alcohol use may serve an impression management function. (JPS)

  6. Dental impression materials.

    PubMed

    Perry, Rachel

    2013-01-01

    It is clear that many impression materials are available to the veterinary dentist. They each have different inherent properties, handling characteristics, and indications for use. A thorough understanding of these concepts is essential if the veterinarian and laboratory technician are to produce meaningful and accurate reproductions of oral structures. New products are constantly being introduced to the dental market, with fantastic claims for ease of use and reproduction of detail. The reader is urged to seek independent research findings when assessing such claims, and make decisions founded in the highest possible levels of evidence. PMID:24006720

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... nanoparticles (generic). 721.10120 Section 721.10120 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... nanoparticles (generic). 721.10120 Section 721.10120 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Specific Chemical Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a) Chemical... as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this...

  9. Fouling-release and chemical activity effects of a siloxane-based material on tunicates.

    PubMed

    Filip, Natalia; Pustam, Amanda; Ells, Veronica; Grosicki, Kathleen M T; Yang, Jin; Oguejiofor, Ikenna; Bishop, Cory D; DeMont, M Edwin; Smith-Palmer, Truis; Wyeth, Russell C

    2016-05-01

    The antifouling performance of a siloxane-based elastomeric impression material (EIM) was compared to that of two silicone fouling-release coatings, Intersleek 757 and RTV-11. In field immersion trials, the EIM caused the greatest reduction in fouling by the solitary tunicate Ciona intestinalis and caused the longest delay in the progression of fouling by two species of colonial tunicate. However, in pseudobarnacle adhesion tests, the EIM had higher attachment strengths. Further laboratory analyses showed that the EIM leached alkylphenol ethoxylates (APEs) that were toxic to C. intestinalis larvae. The EIM thus showed the longest duration of chemical activity measured to date for a siloxane-based coating (4 months), supporting investigations of fouling-release coatings that release targeted biocides. However, due to potential widespread effects of APEs, the current EIM formulation should not be considered as an environmentally-safe antifoulant. Thus, the data also emphasize consideration of both immediate and long-term effects of potentially toxic constituents released from fouling-release coatings. PMID:26986763

  10. 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.

  11. Ultrahigh molecular weight aromatic siloxane polymers

    NASA Technical Reports Server (NTRS)

    Ludwick, L. M.

    1982-01-01

    The condensation of a diol with a silane in toluene yields a silphenylene-siloxane polymer. The reaction of stiochiometric amounts of the diol and silane produced products with molecular weights in the range 2.0 - 6.0 x 10 to the 5th power. The molecular weight of the product was greatly increased by a multistep technique. The methodology for synthesis of high molecular weight polymers using a two step procedure was refined. Polymers with weight average molecular weights in excess of 1.0 x 10 to the 6th power produced by this method. Two more reactive silanes, bis(pyrrolidinyl)dimethylsilane and bis(gamma butyrolactam)dimethylsilane, are compared with the dimethyleminodimethylsilane in ability to advance the molecular weight of the prepolymer. The polymers produced are characterized by intrinsic viscosity in tetrahydrofuran. Weight and number average molecular weights and polydispersity are determined by gel permeation chromatography.

  12. Structure property behavior of polyimide siloxane segmented copolymers

    NASA Technical Reports Server (NTRS)

    Arnold, C. A.; Summers, J. D.; Bott, R. H.; Taylor, L. T.; Ward, T. C.

    1987-01-01

    Procedures were developed for preparing soluble fully imidized polyimide-polydimethyl siloxane segmented copolymers of wide ranging compositions. At low siloxane levels, the materails behave as modified polyimides. At higher concentrations, the materials are analogous to thermoplastic elastomers. Characterization by dynamic mechanical and thermal analysis methods will be reported along with an assesment of the bulk mechanical properties and the surface behavior. The surface behavior is particularly interesting since the materials can be tailored to have siloxane surfaces even at rather low siloxane contents. This influences a number of properties such as the coefficient of friction and, importanly, the degradation of these materials under aggressive oxygen environments (e.g., atomic oxygen, oxygen plasma).

  13. Experimental studies of siloxane polymers and their elastomeric networks

    SciTech Connect

    Kuo, Chung Mien

    1992-12-31

    Siloxane polymers have been investigated systematically for the purpose of a greater understanding of the structure-property relationships in terms of their synthesis, polymer blends and rubber elasticity of their crosslinked networks. This study includes a variety of topological structures: linear, cyclic and crosslinked networks of poly(dimethylsiloxane) (PDMS) and poly(dimethylco-methylphenylsiloxane) copolymers. Siloxane polymers with a narrow molecular weight distribution were prepared by a series of well-characterized organometallic polymerizations. The reaction conditions and mechanisms for preparing polyorganosiloxane chains and networks using organotin catalyst and promoters were discussed. Experimental evidence shows that formamide was one of the best additives to improve the reactivity of the tin dicarboxylate catalyst, which seems to suggest that the nucleophilic function of the additive was on the Sn atom. Since the PDMS and PMPS are immiscible under most conditions, the miscibility and phase behavior of siloxane blends were studied by a static light scattering t technique. THe influence of molar mass, the topological effect of cyclic and linear structures, the end-group effect, and the configurational isomerism effect on miscibility were examined. Silicon networks of PDMS, PMPS and their copolymers were prepared at room temperature using the crosslinked siloxane homopolymer and copolymer networks at equilibrium swelling in organic solvents and in liquid siloxane oligomers were investigated as function of crosslinking density and composition variation. The resulting interaction parameters for PDMS and PMPS from the swollen siloxane networks in siloxane oligomers individually were compared with those from measurements of the corresponding blend systems. Moreover, the stress-strain behavior of the siloxane polymer networks undergoing uniaxial deformation were evaluated by a stress-strain experiment.

  14. 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

  15. [Characteristics of domestically produced siloxane elastomer for making elastic gingival prosthetic device].

    PubMed

    Riakhovskiĭ, A N; Poiurovskaia, I Ia; Kirillova, E V

    2006-01-01

    Gingival prosthetics effectively eliminates esthetic and phonetic disturbances in cases of pronounced gingival recession. Technology for making elastic gingival prosthetic devices of domestically produced siloxane elastomer composition with microwave siloxane vulcanization is described as well as the technique for making combined gingival prosthetics of siloxane composition and colorless plastic. PMID:16482030

  16. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Siloxanes and silicones, aminoalkyl... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9502 Siloxanes and silicones... subject to reporting. (1) The chemical substance identified generically as siloxanes and...

  17. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Siloxanes and silicones, aminoalkyl... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9502 Siloxanes and silicones... subject to reporting. (1) The chemical substance identified generically as siloxanes and...

  18. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Siloxanes and silicones, aminoalkyl... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9502 Siloxanes and silicones... subject to reporting. (1) The chemical substance identified generically as siloxanes and...

  19. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxanes and silicones, aminoalkyl... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9502 Siloxanes and silicones... subject to reporting. (1) The chemical substance identified generically as siloxanes and...

  20. 40 CFR 721.9502 - Siloxanes and silicones, aminoalkyl, fluorooctyl, hydroxy-terminated salt (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxanes and silicones, aminoalkyl... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9502 Siloxanes and silicones... subject to reporting. (1) The chemical substance identified generically as siloxanes and...

  1. Enzymatic synthesis of lignin-siloxane hybrid functional polymers.

    PubMed

    Prasetyo, Endry Nugroho; Kudanga, Tukayi; Fischer, Roman; Eichinger, Reinhard; Nyanhongo, Gibson S; Guebitz, Georg M

    2012-02-01

    This study combines the properties of siloxanes and lignin polymers to produce hybrid functional polymers that can be used as adhesives, coating materials, and/or multifunctionalized thin-coating films. Lignin-silica hybrid copolymers were synthesized by using a sol-gel process. Laccases from Trametes hirsuta were used to oxidize lignosulphonates to enhance their reactivity towards siloxanes and then were incorporated into siloxane precursors undergoing a sol-gel process. In vitro copolymerization studies using pure lignin monomers with aminosilanes or ethoxytrimethylsilane and analysis by ²⁹Si NMR spectroscopy revealed hybrid products. Except for kraft lignin, an increase in lignin concentration positively affected the tensile strength in all samples. Similarly, the viscosity generally increased in all samples with increasing lignin concentration and also affected the curing time. PMID:21751391

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

    SciTech Connect

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

    1996-12-31

    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 infrared (IR) absorption of siloxane migrating to the silicone surface through a thin carbon coating, the aspect of the LMW siloxane migration was observed as a real time plot and the time constant of the migration was calculated. According to the time dependence of IR-absorbance, the migration mostly saturated within only 12 hours after the carbon coating was applied. Also, the time constant showed a dependence on the concentration of added filler in the silicone samples.

  3. Shock compression of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-04-01

    This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

  4. Eyeblinks in formation of impressions.

    PubMed

    Omori, Y; Miyata, Y

    1996-10-01

    The purpose of this study was to investigate the influence of frequency of one's eyeblinks on creating a personal impression. The subjects, 102 males and 127 females, ages 15 to 60 years, rated on a 7-point semantic differential scale a rarely blinking person or a frequently blinking person described on a question-sheet. A factor analysis of the ratings yielded three factors, interpreted as Nervousness, Unfriendliness, and Lack of intelligence. The frequently blinking person was rated as more nervous and less intelligent than the rarely blinking person. Present results provided evidence that frequency of eyeblinks may play an important role on the formation of impressions. Further implications of the findings are discussed. PMID:8902035

  5. Preparation and characterization of siloxane-containing thermoplastic polyimides

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    Copolyimides and homopolyimides of bis(gamma-aminopropyl)tetramethyldisiloxane and 3,3'-diaminobenzophenone have been prepared with benzophenonetetracarboxylic dianhydride. The properties of the copolyimides were compared with those of the homopolyimides to assess the effect of incorporation of siloxane groups in the backbone. Applications of the polymers as adhesives and mouldings are discussed.

  6. Acetylene (ethynyl) terminated polyimide siloxane and process for preparation thereof

    NASA Technical Reports Server (NTRS)

    Stclair, T. L.; ASI primers applied over ste (Inventor)

    1986-01-01

    Siloxane containing addition polyimides having improved physical property characteristics of flexibility, drape, tack, and toughness and the process for preparing and utilizing the same are disclosed. The novelty of this invention appears to reside in the composition and process of preparing addition type polyimides useful as structural adhesives as well as composite matrix materials and the process of preparing the same.

  7. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... tube is a device consisting of a hollow copper tube intended to take an impression of a single tooth... material, such as wax, the remaining end is slipped over the tooth to make the impression....

  8. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... tube is a device consisting of a hollow copper tube intended to take an impression of a single tooth... material, such as wax, the remaining end is slipped over the tooth to make the impression....

  9. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... tube is a device consisting of a hollow copper tube intended to take an impression of a single tooth... material, such as wax, the remaining end is slipped over the tooth to make the impression....

  10. 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

  11. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... tube is a device consisting of a hollow copper tube intended to take an impression of a single tooth... material, such as wax, the remaining end is slipped over the tooth to make the impression....

  12. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... tube is a device consisting of a hollow copper tube intended to take an impression of a single tooth... material, such as wax, the remaining end is slipped over the tooth to make the impression....

  13. 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

  14. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Impression material. 872.3660 Section 872.3660...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification. Impression material is a device composed of materials such as alginate or polysulfide intended to be...

  15. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Impression material. 872.3660 Section 872.3660...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification. Impression material is a device composed of materials such as alginate or polysulfide intended to be...

  16. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Impression material. 872.3660 Section 872.3660...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification. Impression material is a device composed of materials such as alginate or polysulfide intended to be...

  17. Fogging in Polyvinyl Toluene Scintillators

    SciTech Connect

    Cameron, Richard J.; Fritz, Brad G.; Hurlbut, Charles; Kouzes, Richard T.; Ramey, Ashley; Smola, Richard

    2015-02-01

    It has been observed that large polyvinyl toluene (PVT)-based gamma ray detectors can suffer internal “fogging” when exposed to outdoor environmental conditions over long periods of time. When observed, this change results in reduced light collection by photomultiplier tubes connected to the PVT. Investigation of the physical cause of these changes has been explored, and a root cause identified. Water penetration into the PVT from hot, high-humidity conditions results in reversible internal water condensation at room temperature, and permanent micro-fracturing of the PVT at very low environmental temperatures. Mitigation procedures and methods are being investigated.

  18. 76 FR 13660 - Polyvinyl Alcohol From Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-14

    ... 4, 2010 (75 FR 61175). The hearing was held in Washington, DC, on January 25, 2011, and all persons... COMMISSION Polyvinyl Alcohol From Taiwan Determination On the basis of the record \\1\\ developed in the... United States is materially injured by reason of imports from Taiwan of polyvinyl alcohol, provided...

  19. Polyvinyl alcohol hydrogels for iontohporesis

    NASA Astrophysics Data System (ADS)

    Bera, Prasanta; Alam, Asif Ali; Arora, Neha; Tibarewala, Dewaki Nandan; Basak, Piyali

    2013-06-01

    Transdermal therapeutic systems propound controlled release of active ingredients through the skin into the systemic circulation in a predictive manner. Drugs administered through these systems escape first-pass metabolism and maintain a steady state scenario similar to a continuous intravenous infusion for up to several days. The iontophoresis deal with the systemic delivery of the bioactive agents (drug) by applying an electric current. It is basically an injection without the needle. The iontophoretic system requires a gel-based matrix to accommodate the bioactive agent. Hydrogels have been used by many investigators in controlled-release drug delivery systems because of their good tissue compatibility and easy manipulation of swelling level and, thereby, solute permeability. In this work we have prepared polyvinyl alcohol (PVA) hydrogel. We have cross linked polyvinyl alcohol chemically with Glutaraldehyde with different wt%. FTIR study reveals the chemical changes during cross linking. Swelling in water, is done to have an idea about drug loading and drug release from the membrane. After drug loading to the hydrogels, we have studied the drug release property of the hydrogels using salicylic acid as a model drug.

  20. Ultra-high molecular weight silphenylene-siloxane polymers

    NASA Technical Reports Server (NTRS)

    Patterson, W. J.; Hundley, N. H.; Ludwick, L. M.

    1984-01-01

    Silphenylene-siloxane copolymers with molecular weights above one million were prepared using a two stage polymerization technique. The technique was successfully scaled up to produce 50 grams of this high polymer in a single run. The reactive monomer approach was also investigated using the following aminosilanes: bis(dimethylamino)dimethylsilane, N,N-bis(pyrrolidinyl)dimethylsilane and N,N-bis(gamma-butyrolactam)dimethylsilane). Thermal analyses were performed in both air and nitrogen. The experimental polymers decomposed at 540 to 562 C, as opposed to 408 to 426 C for commercial silicones. Differential scanning calorimetry showed a glass transition (Tg) at -50 to -55 C for the silphenylene-siloxane copolymer while the commercial silicones had Tg's at -96 to -112 C.

  1. Ultra-High-Molecular-Weight Silphenylene/Siloxane Elastomers

    NASA Technical Reports Server (NTRS)

    Hundley, N. H.; Patterson, W. J.

    1989-01-01

    Elastomers enhance thermal and mechancial properties. Capable of performing in extreme thermal/oxidative environments and having molecular weights above 10 to the sixth power prepared and analyzed in laboratory experiments. Made of methylvinylsilphenylene-siloxane terpolymers, new materials amenable to conventional silicone-processing technology. Similarly formulated commercial methyl-vinyl silicones, vulcanized elastomers exhibit enhance thermal/oxidative stability and equivalent or superior mechanical properties.

  2. The occurrence and fate of siloxanes in wastewater treatment plant in Harbin, China.

    PubMed

    Li, Bo; Li, Wen-Long; Sun, Shao-Jing; Qi, Hong; Ma, Wan-Li; Liu, Li-Yan; Zhang, Zi-Feng; Zhu, Ning-Zheng; Li, Yi-Fan

    2016-07-01

    The occurrence and fate of four cyclic (D3 to D6) and 10 linear (L5 to L14) siloxanes were investigated in influent and effluent wastewater, sludge from a wastewater treatment plant (WWTP), and surrounding air and soil within the WWTP in Harbin, Northeast China. The mean concentrations of total siloxanes in influent and effluent were 4780 and 997 ng/L and in excess sludge and aerobic sludge were 25.1 and 32.3 μg/g dw, respectively. The concentrations in air and soil within the WWTP were 243 ng/m(3) and 4960 ng/g dw, respectively. A similar composition profile of siloxanes in influent and sludge suggests their same source. Seasonal variation with concentration was comprehensively studied. It was found that temperature and rainfall are the two important factors for the seasonal variation of siloxanes. Adsorption with sewage sludge was the major way for the removal of siloxanes during the municipal wastewater treatment process. Overall, on a daily basis, the mass loading of the Σsiloxanes into the WWTP, out of the WWTP with the effluent and sludge, were estimated to be 3.0, 0.6 and 1.3 kg, respectively. In general, 21 % of siloxanes were discharged into the receiving body (Songhua River), 43 % of siloxanes were absorbed on sludge, and 36 % of siloxanes were lost during the whole process of WWTP. PMID:27023806

  3. Photoinduced Bending of Self-Assembled Azobenzene-Siloxane Hybrid.

    PubMed

    Guo, Sufang; Matsukawa, Kimihiro; Miyata, Takashi; Okubo, Tatsuya; Kuroda, Kazuyuki; Shimojima, Atsushi

    2015-12-16

    A novel azobenzene-siloxane hybrid material displaying photoinduced macroscopic motions has been prepared by one-step organosilane self-assembly. Two types of alkoxysilane precursors with either pendant or bridging azobenzene groups were synthesized via thiol-ene click reactions. Hybrid films with well-ordered lamellar structures were obtained by hydrolysis and polycondensation of these precursors. The film with solely pendant azobenzene groups showed reversible and rapid d-spacing variation upon UV-vis irradiation, which was induced by the trans-cis isomerization of azobenzene moieties. The flexible, free-standing film obtained by co-condensation of two types of precursors showed reversible bending-unbending motions upon UV-vis irradiation. The partial cross-linking between the siloxane layers by bridging azobenzene groups was crucial for photoinduced distortion of the film. This film possesses high elastic modulus, good thermal stability, and shows large amplitude of photoinduced bending-unbending over a wide temperature range. This is the first report on photoinduced macroscopic motions of azobenzene-containing siloxane-based materials. These materials possess great potential for applications in smart devices and energy conversion systems. PMID:26575345

  4. Novel Low-Temperature Poss-Containing Siloxane Elastomers

    NASA Technical Reports Server (NTRS)

    Belcher, Marcus A.; Hinkley, Jeffrey A.; Kiri, Neha N.; Lillehei, Peter T.

    2008-01-01

    One route to increased aircraft performance is through the use of flexible, shape-changeable aerodynamics effectors. However, state of the art materials are not flexible or durable enough over the required broad temperature range. Mixed siloxanes were crosslinked by polyhedral oligomeric silsesquioxanes (POSS) producing novel materials that remained flexible and elastic from -55 to 94 C. POSS molecules were chemically modified to generate homogeneous distributions within the siloxane matrix. High resolution scanning electron microscope (HRSEM) images indicated homogenous POSS distribution up to 0.8 wt %. Above the solubility limit, POSS aggregates could be seen both macroscopically and via SEM (approx.60-120 nm). Tensile tests were performed to determine Young s modulus, tensile strength, and elongation at break over the range of temperatures associated with transonic aircraft use (-55 to 94 C; -65 to 200 F). The siloxane materials developed here maintained flexibility at -55 C, where previous candidate materials failed. At room temperature, films could be elongated up to 250 % before rupturing. At -55 and 94 C, however, films could be elongated up to 400 % and 125 %, respectively.

  5. Characterization of high performance randomly segmented poly(urethane siloxane) and poly(imide siloxane) block copolymers

    NASA Astrophysics Data System (ADS)

    Doǧan, Türkan; Baydoǧan, Nilgün; Köken, Nesrin

    2016-03-01

    Poly(imide siloxane) block copolymers with the same polydimethlysiloxane(APPS) were prepared by using 4,4'-oxydianiline (ODA) and Benzofenon-3,3,4,4-tetrakarboksilik dianhydride(BTDA) to compose the polyimide hard block. APPS and BTDA composed the polysiloxane soft block. The length of polysiloxane soft blocks increased with increasing the length of polyimide hard block. Copolymerization of soft and hard segments were determined by using this method. Copolymer structures could be obtained by holding constant hard block segments and by adjusting and increasing soft block segments. Thus, more flexible randomly segmented poly(imide siloxane) block copolymers can be obtained. These composed structure as flexible and high performance copolymers were characterized by FT-IR and evaluated. The structures were tested mechanically to detect their elastic recovery property as flexible material. The characterization of the samples enabled to examine flexible substrates in order to use in solar cell, aerospace applications and microelectronic devices.

  6. 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

  7. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact..., in accordance with the following prescribed conditions: (a) The polyvinyl alcohol film is...

  8. A Comparative Evaluation of the Linear Dimensional Accuracy of Four Impression Techniques using Polyether Impression Material.

    PubMed

    Manoj, Smita Sara; Cherian, K P; Chitre, Vidya; Aras, Meena

    2013-12-01

    There is much discussion in the dental literature regarding the superiority of one impression technique over the other using addition silicone impression material. However, there is inadequate information available on the accuracy of different impression techniques using polyether. The purpose of this study was to assess the linear dimensional accuracy of four impression techniques using polyether on a laboratory model that simulates clinical practice. The impression material used was Impregum Soft™, 3 M ESPE and the four impression techniques used were (1) Monophase impression technique using medium body impression material. (2) One step double mix impression technique using heavy body and light body impression materials simultaneously. (3) Two step double mix impression technique using a cellophane spacer (heavy body material used as a preliminary impression to create a wash space with a cellophane spacer, followed by the use of light body material). (4) Matrix impression using a matrix of polyether occlusal registration material. The matrix is loaded with heavy body material followed by a pick-up impression in medium body material. For each technique, thirty impressions were made of a stainless steel master model that contained three complete crown abutment preparations, which were used as the positive control. Accuracy was assessed by measuring eight dimensions (mesiodistal, faciolingual and inter-abutment) on stone dies poured from impressions of the master model. A two-tailed t test was carried out to test the significance in difference of the distances between the master model and the stone models. One way analysis of variance (ANOVA) was used for multiple group comparison followed by the Bonferroni's test for pair wise comparison. The accuracy was tested at α = 0.05. In general, polyether impression material produced stone dies that were smaller except for the dies produced from the one step double mix impression technique. The ANOVA revealed a highly

  9. 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)

  10. 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 siloxanessiloxane) in sludge ranged from 0.05 to 142 (mean: 45.7) μg/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 Σsiloxane 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

  11. Development of novel cycloaliphatic siloxanes for thermal and UV-curable applications

    NASA Astrophysics Data System (ADS)

    Chakraborty, Ruby

    Siloxanes have been extensively used as additives to modulate surface properties such as surface tension, hydrophobicity/hydrophobicity, and adhesion, etc. Although, polydimethyl -siloxane and polydiphenylsiloxane are the most commonly used siloxanes, the properties are at extremes in terms of glass transition temperature and flexibility. It is proposed that the ability to control the properties in between the these extremes can be provided by cycloaliphatic substitutions at the siloxane backbone. It is expected that this substitution might work due to the intermediate backbone rigidity. In order to achieve the above objectives, a synthetic route was developed to prepare cycloaliphatic (cyclopentane and cyclohexane) silane monomers followed by subsequent polymerization and functionalizations to obtain glycidyl epoxy, aliphatic amine and methacrylate telechelic siloxanes. The siloxanes were either thermally or UV-cured depending on end functionalizations. Chemical characterization of monomers, oligomers and polymers were performed using 1H, 13C, 29Si-NMR, FT-IR and GPC. The curing kinetics of photo-induced reactions were investigated through photo-differential scanning calorimetry (PDSC). The oxygen permeability, mechanical, coatings, and release properties of siloxanes were studied as a function of the backbone substitutions. The mechanical, coatings and released properties of cycloaliphatic siloxanes improved with respect to polydimethylsiloxanes. The thermal analysis of the cured films were carried out using differential scanning calorimetry (DSC). Viscoelastic properties of the cured siloxanes due to the variation of substitution at the siloxane backbone were measured using dynamic mechanical thermal analysis (DMTA). The cycloaliphatic substituted siloxanes showed an increased glass transition temperature and permeability but reduced crosslink density, conversion, and rate of curing with respect to polydimethylsiloxanes. Hybrids of siloxanes were prepared with

  12. Computational benchmark for calculation of silane and siloxane thermochemistry.

    PubMed

    Cypryk, Marek; Gostyński, Bartłomiej

    2016-01-01

    Geometries of model chlorosilanes, R3SiCl, silanols, R3SiOH, and disiloxanes, (R3Si)2O, R = H, Me, as well as the thermochemistry of the reactions involving these species were modeled using 11 common density functionals in combination with five basis sets to examine the accuracy and applicability of various theoretical methods in organosilicon chemistry. As the model reactions, the proton affinities of silanols and siloxanes, hydrolysis of chlorosilanes and condensation of silanols to siloxanes were considered. As the reference values, experimental bonding parameters and reaction enthalpies were used wherever available. Where there are no experimental data, W1 and CBS-QB3 values were used instead. For the gas phase conditions, excellent agreement between theoretical CBS-QB3 and W1 and experimental thermochemical values was observed. All DFT methods also give acceptable values and the precision of various functionals used was comparable. No significant advantage of newer more advanced functionals over 'classical' B3LYP and PBEPBE ones was noted. The accuracy of the results was improved significantly when triple-zeta basis sets were used for energy calculations, instead of double-zeta ones. The accuracy of calculations for the reactions in water solution within the SCRF model was inferior compared to the gas phase. However, by careful estimation of corrections to the ΔHsolv and ΔGsolv of H(+) and HCl, reasonable values of thermodynamic quantities for the discussed reactions can be obtained. PMID:26781663

  13. Degradation of polymer electrolyte membrane fuel cell by siloxane in biogas

    NASA Astrophysics Data System (ADS)

    Seo, Ji-Sung; Kim, Da-Yeong; Hwang, Sun-Mi; Seo, Min Ho; Seo, Dong-Jun; Yang, Seung Yong; Han, Chan Hui; Jung, Yong-Min; Guim, Hwanuk; Nahm, Kee Suk; Yoon, Young-Gi; Kim, Tae-Young

    2016-06-01

    We studied the degradation and durability of polymer electrolyte membrane fuel cell (PEMFC) at membrane-electrode-assembly (MEA) level by injection of octamethylcyclotetrasiloxane (D4) as a representative siloxane, which has been found in many industrial and personal products. Specifically, i) GC/MS analysis demonstrated that the ring-opening polymerization of D4 could result in the formation of various linear and cyclic siloxanes in both electrodes of MEA; ii) post-test analysis revealed that the transformed siloxanes were transported from the anode to the cathode via free-volumes in the polymer membrane; iii) RDE measurement and DFT calculation revealed that D4 was not directly responsible for the electrocatalytic activity of Pt; iv) electrochemical analysis demonstrated that the residual methyl groups of siloxane and various siloxanes did not hinder the proton transport in the polymer membrane; and v) siloxanes accumulated in the primary and secondary pores with the exception of an external surface of carbon, causing an increase in the oxygen reactant's resistance and resulting in a decrease of the cell performance. In addition, we confirmed that injection of D4 did not affect the carbon corrosion adversely because the siloxane had little influence on water sorption in the catalyst layer.

  14. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification... device is intended to provide models for study and for production of restorative prosthetic devices,...

  15. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification... device is intended to provide models for study and for production of restorative prosthetic devices,...

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

    SciTech Connect

    Nam, Sangchul; Namkoong, Wan; Kang, Jeong-Hee; Park, Jin-Kyu; Lee, Namhoon

    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.

  17. Selectivity and limitations of carbon sorption tubes for capturing siloxanes in biogas during field sampling.

    PubMed

    Tansel, Berrin; Surita, Sharon C

    2016-06-01

    Siloxane levels in biogas can jeopardize the warranties of the engines used at the biogas to energy facilities. The chemical structure of siloxanes consists of silicon and oxygen atoms, alternating in position, with hydrocarbon groups attached to the silicon side chain. Siloxanes can be either in cyclic (D) or linear (L) configuration and referred with a letter corresponding to their structure followed by a number corresponding to the number of silicon atoms present. When siloxanes are burned, the hydrocarbon fraction is lost and silicon is converted to silicates. The purpose of this study was to evaluate the adequacy of activated carbon gas samplers for quantitative analysis of siloxanes in biogas samples. Biogas samples were collected from a landfill and an anaerobic digester using multiple carbon sorbent tubes assembled in series. One set of samples was collected for 30min (sampling 6-L gas), and the second set was collected for 60min (sampling 12-L gas). Carbon particles were thermally desorbed and analyzed by Gas Chromatography Mass Spectrometry (GC/MS). The results showed that biogas sampling using a single tube would not adequately capture octamethyltrisiloxane (L3), hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). Even with 4 tubes were used in series, D5 was not captured effectively. The single sorbent tube sampling method was adequate only for capturing trimethylsilanol (TMS) and hexamethyldisiloxane (L2). Affinity of siloxanes for activated carbon decreased with increasing molecular weight. Using multiple carbon sorbent tubes in series can be an appropriate method for developing a standard procedure for determining siloxane levels for low molecular weight siloxanes (up to D3). Appropriate quality assurance and quality control procedures should be developed for adequately quantifying the levels of the higher molecular weight siloxanes in biogas with sorbent tubes

  18. Preliminary impression techniques for microstomia patients.

    PubMed

    Kumar, K Aswini; Bhat, Vinaya; Nair, K Chandrasekheran; Suresh, Reshma

    2016-01-01

    The Prosthetic rehabilitation of microstomia patients presents difficulties at all the stages. The difficulty starts with the preliminary impression making. This is due to the tongue rigidity and the decreased oral opening. A maximum oral opening which is smaller than the size of the tray can make prosthetic treatment challenging. Due to the restricted mouth opening, insertion and removal of the impression trays is extremely cumbersome and various modifications of the trays have been used in the past. Among these are the flexible trays and the sectional trays used with different modes of reassembling the segments extra orally after the impression is made. This article reviews the literature published from 1971 to 2015 concerning preliminary impression techniques used in making impressions for patients with microstomia based on various tray designs. An electronic search was performed across three databases (PubMed, Science Direct and Google Scolar) for relevant citations. The keywords/combinations used for the search were microstomia, limited/constricted/restricted mouth opening/oral access, trismus, sectional trays, impressions and prosthetic/prosthodontic rehabilitation. The search was limited to papers written in English which resulted in a total of 45 related articles of which 17 articles were included for discussion of this review. PMID:27621540

  19. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  20. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  1. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  2. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  3. Structure-property relationships in silica-siloxane nanocomposite materials

    SciTech Connect

    Ulibarri, T.A.; Derzon, D.K.; Wang, L.C.

    1997-03-01

    The simultaneous formation of a filler phase and a polymer matrix via in situ sol-gel techniques provides silica-siloxane nanocomposite materials of high strength. This study concentrates on the effects of temperature and relative humidity on a trimodal polymer system in an attempt to accelerate the reaction as well as evaluate subtle process- structure-property relations. It was found that successful process acceleration is only viable for high humidity systems when using the tin(IV) catalyst dibutyltin dilaurate. Processes involving low humidity were found to be very temperature and time dependent. Bimodal systems were investigated and demonstrated that the presence of a short-chain component led to enhanced material strength. This part of the study also revealed a link between the particle size and population density and the optimization of material properties.

  4. 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.

  5. Environmentally friendly antibacterial cotton textiles finished with siloxane sulfopropylbetaine.

    PubMed

    Chen, Shiguo; Chen, Shaojun; Jiang, Song; Xiong, Meiling; Luo, Junxuan; Tang, Jiaoning; Ge, Zaochuan

    2011-04-01

    This paper reports a novel environmentally friendly antibacterial cotton textile finished with reactive siloxane sulfopropylbetaine(SSPB). The results show that SSPB can be covalently bound onto the cotton textile surface, imparting perdurable antibacterial activity. The textiles finished with SSPB have been investigated systematically from the mechanical properties, thermal stability, hydrophilic properties and antibacterial properties. It is found that the hydrophilicity and breaking strength are improved greatly after the cotton textiles are finished with SSPB. Additionally, the cotton textiles finished with SSPB exhibit good antibacterial activities against gram-positive bacteria Staphylococcus aureus (S.aureus, ATCC 6538), gram-negative bacteria Escherichia coli (E.coli, 8099) and fungi Candida albicans (C.albicans, ATCC 10231). Moreover, SSPB is nonleachable from the textiles, and it does not induce skin stimulation and is nontoxic to animals. Thus, SSPB is ideal candidate for environmentally friendly antibacterial textile applications. PMID:21417413

  6. Nanostructured Self-Assembling Systems Based on Functional Poly(Urethane/Siloxane)S

    NASA Astrophysics Data System (ADS)

    Savelyev, Yuri

    Novel hybride organo-inorganic systems based on urethane-, urea-crown ether- and siloxane-containing monomers and oligomers have been developed by sol-gel method. Structure-properties relationships were discussed.

  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. Accuracy of Digital vs. Conventional Implant Impressions

    PubMed Central

    Lee, Sang J.; Betensky, Rebecca A.; Gianneschi, Grace E.; Gallucci, German O.

    2015-01-01

    The accuracy of digital impressions greatly influences the clinical viability in implant restorations. The aim of this study is to compare the accuracy of gypsum models acquired from the conventional implant impression to digitally milled models created from direct digitalization by three-dimensional analysis. Thirty gypsum and 30 digitally milled models impressed directly from a reference model were prepared. The models were scanned by a laboratory scanner and 30 STL datasets from each group were imported to an inspection software. The datasets were aligned to the reference dataset by a repeated best fit algorithm and 10 specified contact locations of interest were measured in mean volumetric deviations. The areas were pooled by cusps, fossae, interproximal contacts, horizontal and vertical axes of implant position and angulation. The pooled areas were statistically analysed by comparing each group to the reference model to investigate the mean volumetric deviations accounting for accuracy and standard deviations for precision. Milled models from digital impressions had comparable accuracy to gypsum models from conventional impressions. However, differences in fossae and vertical displacement of the implant position from the gypsum and digitally milled models compared to the reference model, exhibited statistical significance (p<0.001, p=0.020 respectively). PMID:24720423

  9. 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

  10. A new class of high performance protective coatings for the rail industry based on siloxane technology

    SciTech Connect

    Hull, C.G.; Woods, J.J.

    1995-12-01

    A novel new class of protective coatings has been developed which is based on the hybridization of inorganic siloxane polymers with organic epoxy polymers. These coatings exhibit the corrosion resistance of an epoxy and weathering resistance superior to the best aliphatic polyurethane. As a result, traditional high performance 3-coat inorganic zinc/epoxy/polyurethane coatings can be replaced with 2-coat zinc/epoxy siloxane coatings with significant savings in applied cost.

  11. Giving the wrong impression: food and beverage brand impressions delivered to youth through popular movies

    PubMed Central

    Skatrud-Mickelson, Monica; Adachi-Mejia, Anna M.; MacKenzie, Todd A.; Sutherland, Lisa A.

    2012-01-01

    Background Marketing on television showcases less-healthful options, with emerging research suggesting movies promote similar products. Given the obesity epidemic, understanding advertising to youth should be a public health imperative. The objective of this study was to estimate youth impressions to food and beverages delivered through movies. Methods Impressions were calculated by dividing US receipts annually into average movie ticket prices, then multiplying this by the number of brand appearances. Examination by ratings, product types and ages were conducted by Spearman rank correlation coefficient tests. Results Youth in the USA saw over 3 billion food, beverage or food–retail establishment (FRE) impressions on average, annually from 1996 to 2005. Those aged 12–18 viewed over half of all impressions, with PG-13-rated movies containing 61.5% of impressions. There were no significant trends in brand appearances by food, beverage or FRE impressions over the decade, although there was a decreasing trend in R-rated impressions for both foods (P< 0.01) and beverages (P< 0.01), but not FREs (P= 0.08). Conclusions Movies promote billions of food and beverage impressions annually to youth. Given the public health crisis of obesity, future research should further investigate these trends, as well as the potential association of these unhealthy exposures in youth. PMID:22076600

  12. Dimensional Accuracy of Hydrophilic and Hydrophobic VPS Impression Materials Using Different Impression Techniques - An Invitro Study

    PubMed Central

    Pilla, Ajai; Pathipaka, Suman

    2016-01-01

    Introduction The dimensional stability of the impression material could have an influence on the accuracy of the final restoration. Vinyl Polysiloxane Impression materials (VPS) are most frequently used as the impression material in fixed prosthodontics. As VPS is hydrophobic when it is poured with gypsum products, manufacturers added intrinsic surfactants and marketed as hydrophilic VPS. These hydrophilic VPS have shown increased wettability with gypsum slurries. VPS are available in different viscosities ranging from very low to very high for usage under different impression techniques. Aim To compare the dimensional accuracy of hydrophilic VPS and hydrophobic VPS using monophase, one step and two step putty wash impression techniques. Materials and Methods To test the dimensional accuracy of the impression materials a stainless steel die was fabricated as prescribed by ADA specification no. 19 for elastomeric impression materials. A total of 60 impressions were made. The materials were divided into two groups, Group1 hydrophilic VPS (Aquasil) and Group 2 hydrophobic VPS (Variotime). These were further divided into three subgroups A, B, C for monophase, one-step and two-step putty wash technique with 10 samples in each subgroup. The dimensional accuracy of the impressions was evaluated after 24 hours using vertical profile projector with lens magnification range of 20X-125X illumination. The study was analyzed through one-way ANOVA, post-hoc Tukey HSD test and unpaired t-test for mean comparison between groups. Results Results showed that the three different impression techniques (monophase, 1-step, 2-step putty wash techniques) did cause significant change in dimensional accuracy between hydrophilic VPS and hydrophobic VPS impression materials. One-way ANOVA disclosed, mean dimensional change and SD for hydrophilic VPS varied between 0.56% and 0.16%, which were low, suggesting hydrophilic VPS was satisfactory with all three impression techniques. However, mean

  13. Facial feedback effects on impression formation.

    PubMed

    Ohira, H; Kurono, K

    1993-12-01

    Two experiments were conducted to examine effects of facial expressions upon social cognitive processes in which the impression of another person is formed. In each experiment, 30 female college students were induced to display or conceal their facial reactions to a hypothetical target person whose behaviors were mildly hostile (Exp. 1) or mildly friendly (Exp. 2), or their facial expressions were not manipulated. Displaying the facial expressions shifted the impression into the congruent directions with hedonic values corresponding to the facial expressions. Concealing the facial expressions, however, did not influence impression formation. Also, the positive-negative asymmetry was observed in the facial feedback effects, that is, the negative facial expression had a stronger effect on social cognition than the positive one. PMID:8170774

  14. Comparative study of dimensional accuracy of different impression techniques using addition silicone impression material.

    PubMed

    Penaflor, C F; Semacio, R C; De Las Alas, L T; Uy, H G

    1998-01-01

    This study compared dimensional accuracy of the single, double with spacer, double with cut-out and double mix impression technique using addition silicone impression material. A typhodont containing Ivorine teeth model with six (6) full-crown tooth preparations were used as the positive control. Two stone replication models for each impression technique were made as test materials. Accuracy of the techniques were assessed by measuring four dimensions on the stone dies poured from the impression of the Ivorine teeth model. Results indicated that most of the measurements for the height, width and diameter slightly decreased and a few increased compared with the Ivorine teeth model. The double with cut-out and double mix technique presents the least difference from the master model as compared to the two latter impression techniques. PMID:10202524

  15. Impression Testing of Self-Healing Polymers

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.; Huber, Amy

    2005-01-01

    As part of the BIOSANT program (biologically-inspired smart nanotechnology), scientists at NASA-Langley have identified a "self-healing" plastic that spontaneously closes the hole left by the passage of a bullet. To understand and generalize the phenomenon in question, the mechanical properties responsible for this ability are being explored. Low-rate impression testing was chosen to characterize post-yield material properties, and it turned out that materials that heal following ballistic puncture also show up to 80% healing of the low-rate impression. Preliminary results on the effects of temperature and rate of puncture are presented.

  16. Pressures involved in making upper edentulous impressions.

    PubMed

    Rihani, A

    1981-12-01

    A study was made of the pressures exerted on the upper denture-bearing area in three patients each with a different type of palatal vault. A method of measuring the relative pressures in different regions of the upper denture bearing area was devised. These pressures were registered with the use of manometers while making an impression in close fitting acrylic resin special trays. The results indicated that the main pressure regions during impression making were near the center of the palate and these pressures diminished toward the buccal borders. PMID:7028974

  17. [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

  18. Additivity of Clothing Cues in First Impressions.

    ERIC Educational Resources Information Center

    Lennon, Sharron J.

    1986-01-01

    The theory of information integration was used to predict that in first impression situations, clothing/physical appearance cues have differential importance depending upon the type of judgment elicited. Female college students (N=104) viewed and responded to slides of colored line drawings of female stimulus persons. Multiple regression of data…

  19. The Trouble with Applicant Impression Management.

    ERIC Educational Resources Information Center

    Ralston, Steven M.; Kirkwood, William G.

    1999-01-01

    Suggests that applicant impression management (AIM) is more harmful to employment interviewing than is currently suspected. Offers a conceptual model of AIM that is consistent with employment interviewing practice. Presents and critiques three arguments used to defend AIM. Examines a model for helping employers conduct interviews that minimize the…

  20. Personality Impressions Elicited by Accented English Speech.

    ERIC Educational Resources Information Center

    Gallois, Cynthia; Callan, Victor J.

    1981-01-01

    Australian born male and female students listened to tapes of accented English speech and were asked to relate their impressions and judgments of the speakers' personalities. Results indicated that the nationality and sex of the speakers were factors which influenced the judgments made about them by the Australian students. (Author/APM)

  1. Patterns of Vocalization and Impression Formation

    ERIC Educational Resources Information Center

    Hayes, Donald P.; Bouma, Gary D.

    1975-01-01

    This article discusses the interactive behavior that accompanies verbal exchange. It specifically describes a set of experiments designed to isolate an important subset of interactive behavior, the vocal (as opposed to the verbal) and to relate this information to a wide range of social impressions resulting from verbal exchange. (Available from…

  2. Impressive Subcutaneous Calcifications in Systemic Lupus Erythematosus

    PubMed Central

    DIMA, Alina; BERZEA, Ioana; BAICUS, Cristian

    2015-01-01

    Dystrophic calcinosis cutis was commonly described in long-term dermatomyositis or systemic sclerosis, being rarely reported in other connective tissue diseases. We report the case of a 65-years old woman with an only 5-years history of systemic lupus erythematosus, who presents with multiple, impressive subcutaneous calcified masses and biological normal serum calcium and phosphate levels. PMID:26225152

  3. A Modified Impress Method for Beginning Readers.

    ERIC Educational Resources Information Center

    Saunders, Russell W., Jr.

    A modified impress approach to teaching reading has been successfully used in a program involving first grade students. The program was multisensory and included aural, oral, visual, and kinesthetic learning experiences gained through listening, group discussions, dramatic play, art activities, audience reading, and recorded oral reading. These…

  4. Synthesis and evaluation of novel siloxane-methacrylate monomers used as dentin adhesives

    PubMed Central

    Ge, Xueping; Ye, Qiang; Song, Linyong; Misra, Anil; Spencer, Paulette

    2014-01-01

    Objectives The objectives of this study were to synthesize two new siloxane-methacrylate (SM) monomers for application in dentin adhesives and to investigate the influence of different functionality of the siloxane-containing monomers on the adhesive photopolymerization, water sorption, and mechanical properties. Materials and method Two siloxane-methacrylate monomers (SM1 and SM2) with four and eight methacrylate groups were synthesized. Dentin adhesives containing BisGMA, HEMA and the siloxane-methacrylate monomers were photo-polymerized. The experimental adhesives were compared with the control adhesive (HEMA/BisGMA 45/55 w/w) and characterized with regard to degree of conversion (DC), water miscibility of the liquid resin, water sorption and dynamic mechanical analysis (DMA). Results The experimental adhesives exhibited improved water miscibility as compared to the control. When cured in the presence of 12 wt % water to simulate the wet environment of the mouth, the SM-containing adhesives showed DC comparable to the control. The experimental adhesives showed higher rubbery modulus than the control under dry conditions. Under wet conditions, the mechanical properties of the formulations containing SM monomer with increased functionality were comparable with the control, even with more water sorption. Significance The concentration and functionality of the newly synthesized siloxane-methacrylate monomers affected the water miscibility, water sorption and mechanical properties of the adhesives. The experimental adhesives show improved water compatibility compared with the control. The mechanical properties were enhanced with an increase of the functionality of the siloxane-containing monomers. The results provide critical structure/property relationships and important information for future development of durable, versatile siloxane-containing dentin adhesives. PMID:24993811

  5. A novel chemically selective siloxane polymer for chemical vapor sensing

    NASA Astrophysics Data System (ADS)

    Huang, Jia; Jiang, Yadong; Du, Xiaosong; Bi, Juan

    2010-10-01

    A new hydrogen-bond acidic carbosiloxane polymer for quartz crystal microbalance sensors (QCMs) application was synthesized via O-alkylation, Claisen rearrange, hydrosilylation reaction and functionalized the polysiloxane with trifluoroacetone groups (TFA). The trifluoroisopropanol functionalized polysiloxane was characterized by FT-IR and 1HNMR. And this novel siloxane polymer was coated onto AT-cut 8 MHz QCM sensors to investigate its gas sensitive responses to the organophosphorus nerve agent stimulant dimethyl methylphosphonate (DMMP) vapor as well as other interfering organic vapors. The research work indicated that frequency shifts of the trifluoroisopropanol functionalized polysiloxane based QCM sensor to the DMMP vapor were completely linear, and with a regression coefficient of 0.9973 in the concentration range of 10-60 ppm. In addition, the sensitivity of the fabricated QCM sensors to DMMP was up to 10.64 Hz/ ppm, and much higher than the other interfering vapors, limits of detection (LODs) of the QCM sensors was 0.28 ppm, thus high selectivity to DMMP was demonstrated in this work.

  6. 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-μm and tens-μm, 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-μm scale wrinkles first formed, subsequently the tens-μm 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.

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

    SciTech Connect

    Suzuki, Kazumasa; Tokudome, Yasuaki Takahashi, Masahide

    2014-10-21

    Nested wrinkle structures, hierarchical surface wrinkles of different periodicities of sub-μm and tens-μm, 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-μm scale wrinkles first formed, subsequently the tens-μm 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.

  8. 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

  9. [Complications Resulting from Taking Ear Impressions].

    PubMed

    Sugiuchi, Tomoko; Kodera, Kazuoki; Zusho, Hiroyuki; Asano, Yoshikazu; Kanesada, Keiko; Hayashida, Mitsuhiro; Kanaya, Koichiro; Tokumaru, Takeshi

    2015-08-01

    In 2012, we carried out a study in a large sample to understand the secondary injuries caused during the taking ear impressions for hearing aids. This study is a follow-up of previous research conducted in 1986 (285 medical institutions) and 1999 (98 medical institutions). We posted a questionnaire survey to the otolaryngology departments of 3,257 medical institutions. The response rate to the questionnaire was 62.9% (2,050 of the 3,257 institutions), and the results indicated that 301 of the 2050 institutions (14.7%) had experience with secondary injuries, with a total of 460 cases reported. In 342 of the 460 cases (74.3%), the secondary injuries occurred at hearing-aid dealerships, followed by 67 cases (14.6%) at affiliated medical institutions, and 51 cases (11.1%) in other locations, including other medical institutions, rehabilitation counseling centers, and educational institutions. The most common type of secondary injury (298 cases, 64.8%) was caused by the presence of foreign bodies in the ear, which in turn was a result of complications occurring during the removal of residual ear impression material. Of these 298 cases, 32 required excision of the foreign bodies and surgical intervention under general anesthesia. The remaining 10 cases exhibited isolated tympanic membrane perforation without foreign body-related complications. Furthermore, 146 cases (31.7%) developed bleeding and otitis externa following removal of the ear impression, and there were reports of cases with bleeding that required long-term outpatient care and treatment. Therefore, since retention of a foreign body in the ear and tympanic membrane perforation can occur even in patients without a history of surgery or prior otologic history, adjustment of hearing aids requires prior otorhinolaryngological examination. Furthermore, because of the risk of secondary injury when taking ear impressions, this procedure must be performed with caution under the guidance of an otolaryngologist. PMID

  10. 40 CFR 721.6170 - Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6,6-tetramethyl-4-(2-propenyloxy...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxanes and silicones, Me hydrogen... Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6,6-tetramethyl-4-(2-propenyloxy)piperdine... identified as siloxanes and silicones, Me hydrogen, reaction products with...

  11. 40 CFR 721.6170 - Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6,6-tetramethyl-4-(2-propenyloxy...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxanes and silicones, Me hydrogen... Siloxanes and silicones, Me hydrogen, reaction products with 2,2,6,6-tetramethyl-4-(2-propenyloxy)piperdine... identified as siloxanes and silicones, Me hydrogen, reaction products with...

  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, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Siloxanes and silicones, de-Me, 3... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3... to reporting. (1) The chemical substance identified as siloxanes and silicones, de-Me, 3-...

  13. 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

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Siloxanes and silicones, de-Me, 3... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3... to reporting. (1) The chemical substance identified as siloxanes and silicones, de-Me, 3-...

  14. 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

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxanes and silicones, de-Me, 3... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3... to reporting. (1) The chemical substance identified as siloxanes and silicones, de-Me, 3-...

  15. 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

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Siloxanes and silicones, de-Me, 3... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3... to reporting. (1) The chemical substance identified as siloxanes and silicones, de-Me, 3-...

  16. 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

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxanes and silicones, de-Me, 3... SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.9517 Siloxanes and silicones, de-Me, 3... to reporting. (1) The chemical substance identified as siloxanes and silicones, de-Me, 3-...

  17. 40 CFR 721.9516 - Siloxanes and silicones, 3-[(2-aminoethyl) amino]propyl Me, di-Me, reaction products with...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Siloxanes and silicones, 3- propyl Me... Substances § 721.9516 Siloxanes and silicones, 3- propyl Me, di-Me, reaction products with polyethylene...) The chemical substance identified generically as siloxanes and silicones, 3- propyl Me,...

  18. 40 CFR 721.9516 - Siloxanes and silicones, 3-[(2-aminoethyl) amino]propyl Me, di-Me, reaction products with...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Siloxanes and silicones, 3- propyl Me... Substances § 721.9516 Siloxanes and silicones, 3- propyl Me, di-Me, reaction products with polyethylene...) The chemical substance identified generically as siloxanes and silicones, 3- propyl Me,...

  19. Odor Impression Prediction from Mass Spectra

    PubMed Central

    Nakamoto, Takamichi

    2016-01-01

    The sense of smell arises from the perception of odors from chemicals. However, the relationship between the impression of odor and the numerous physicochemical parameters has yet to be understood owing to its complexity. As such, there is no established general method for predicting the impression of odor of a chemical only from its physicochemical properties. In this study, we designed a novel predictive model based on an artificial neural network with a deep structure for predicting odor impression utilizing the mass spectra of chemicals, and we conducted a series of computational analyses to evaluate its performance. Feature vectors extracted from the original high-dimensional space using two autoencoders equipped with both input and output layers in the model are used to build a mapping function from the feature space of mass spectra to the feature space of sensory data. The results of predictions obtained by the proposed new method have notable accuracy (R≅0.76) in comparison with a conventional method (R≅0.61). PMID:27326765

  20. Odor Impression Prediction from Mass Spectra.

    PubMed

    Nozaki, Yuji; Nakamoto, Takamichi

    2016-01-01

    The sense of smell arises from the perception of odors from chemicals. However, the relationship between the impression of odor and the numerous physicochemical parameters has yet to be understood owing to its complexity. As such, there is no established general method for predicting the impression of odor of a chemical only from its physicochemical properties. In this study, we designed a novel predictive model based on an artificial neural network with a deep structure for predicting odor impression utilizing the mass spectra of chemicals, and we conducted a series of computational analyses to evaluate its performance. Feature vectors extracted from the original high-dimensional space using two autoencoders equipped with both input and output layers in the model are used to build a mapping function from the feature space of mass spectra to the feature space of sensory data. The results of predictions obtained by the proposed new method have notable accuracy (R≅0.76) in comparison with a conventional method (R≅0.61). PMID:27326765

  1. 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)

  2. 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

  3. Impression Management Training: Conceptualization and Application to Personal Selling.

    ERIC Educational Resources Information Center

    Leathers, Dale G.

    1988-01-01

    Discusses the importance of impression management, an individual's conscious attempt to exercise control over selected communicative behaviors and cues for purposes of making a desired impression. Provides a comprehensive conceptualization of the impression-management process, and demonstrates how this process can facilitate effective training of…

  4. Clinicians reaping benefits of new concepts in impressioning.

    PubMed

    Lawson, Nathaniel C; Burgess, John O

    2015-02-01

    While conventional elastomeric impression materials are still being used to generate excellent impressions, the future of impression-taking is undoubtedly with digital intraoral scanners. Advances in scanning systems are making this technology easier to use and more practical for dentists. PMID:25822643

  5. Bonded Interactions in Silica Polymorphs, Silicates and Siloxane Molecules

    SciTech Connect

    Gibbs, Gerald V.; Wallace, Adam F.; Cox, David F.; Downs, R. T.; Ross, Nancy L.; Rosso, Kevin M.

    2009-08-01

    Experimental model electron density distributions recorded for the silica polymorphs coesite and stishovite are comparable with electron density distributions calculated for a variety of silicates and siloxane molecules. The Si-O bond lengths and Si-O-Si angles calculated with first principles density functional theory methods as a function of pressure are also comparable with the bond lengths and angles observed for coesite and quartz within the experimental error. The similarity of the topological properties of the Si-O bonded interactions and the experimental and the geometry optimized structures for the silica polymorphs provides a basis for understanding the properties and crystal chemistry in terms of a molecular-based model. The agreement supports the argument that the bulk of the structural, physical and thermodynamic properties of the silica polymorphs are intrinsic properties of the molecular-like coordinated polyhedra such that the silica polymorphs can be pictured as ‘supermolecules’ of silica bound by the virtually same forces that bind the Si and O atoms in simple siloxane molecules. The topology of the electron density distribution is consistent with the assertion that the Si-O bonded interaction arises from the net electrostatic attraction exerted on the nuclei by the electron density accumulated between the Si and O atoms. The correlation between the Si-O bond length and Si-O-Si angle is ascribed to the progressive local concentration of the electron density in the nonbonded region of the O atom as the bond length increases and angle decreases rather then to bonded interactions involving the d-orbitals on Si. On the basis of the proximity of the bond critical point, rc, to the nodal surface of the Laplacian, (nabla)2ρ(rc), and the values of ρ(rc) and G(rc)/ρ(rc), the Si-O bond qualifies as an intermediate bonded interaction. For bonded interactions of intermediate character, (nabla

  6. The Bidimensional Impression Management Index (BIMI): measuring agentic and communal forms of impression management.

    PubMed

    Blasberg, Sabrina A; Rogers, Katherine H; Paulhus, Delroy L

    2014-01-01

    Measures of impression management have yet to incorporate two-factor models of person perception. The 2 primary factors are often labeled agency and communion. In Study 1, we assembled a new measure of impression management—the Bidimensional Impression Management Index (BIMI): It comprises 2 subscales designed specifically to tap agentic and communal content. Both subscales showed adequate alpha reliabilities under both honest and faking conditions. In Study 2, the BIMI was cross-validated in a new sample: The subscales remained relatively independent, and their reliabilities remained solid. A coherent pattern of personality correlates also supported the validities of both subscales. In Study 3, the differential sensitivity of the 2 subscales was demonstrated by manipulating the job type in simulated job applications. Implications and applications of the BIMI are discussed. PMID:24328818

  7. Chemical enhancement of footwear impressions in urine on fabric.

    PubMed

    Farrugia, Kevin J; Bandey, Helen; Bleay, Steve; NicDaéid, Niamh

    2012-01-10

    A range of chemical techniques were utilised for the enhancement of footwear impressions deposited on a variety of fabric types of different colours with urine 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. Urine samples from different donors were analysed using a spectrofluorophotometer revealing differences between individuals. Results indicated that the enhancement of footwear impressions in urine was possible using amino acid staining techniques whereas protein stains failed to achieve successful enhancement. PMID:21813253

  8. Phoenix Makes an Impression on Mars

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This view from the Surface Stereo Imager on NASA's Phoenix Mars Lander shows the first impression dubbed Yeti and looking like a wide footprint -- made on the Martian soil by the Robotic Arm scoop on Sol 6, the sixth Martian day of the mission, (May 31, 2008).

    Touching the ground is the first step toward scooping up soil and ice and delivering the samples to the lander's experiments.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  9. Reliability of the impression replica technique.

    PubMed

    Falk, Anders; Vult von Steyern, Per; Fransson, Håkan; Thorén, Margareta Molin

    2015-01-01

    The aim of this study was to evaluate the reliability of the impression replica technique with a four-unit zirconia fixed dental prosthesis (FDP). Marginal and internal fit were measured by repeatedly placing the FDP on an epoxy cast using light-body silicone material corresponding to cement. All measured marginal and internal fit points showed varying values. The greatest variations were seen at the most distal margin (33 μm) and at the distal abutment of the FDP (77 μm). The results showed that the technique gives moderate variations and is a useful method to evaluate marginal and internal fit. PMID:25822305

  10. Malleability of social impressions of hyperactive children.

    PubMed

    Granger, D A; Whalen, C K; Henker, B

    1993-12-01

    The role of adults' social cognitions in mediating judgments of hyperactive children's medication-related behavior change was explored. Two hundred eight-eight undergraduates observed two videotaped excerpts of a hyperactive "target" boy playing a group game with two peers. Each target was taking either methylphenidate (0.6 mg/kg) during both excerpts, placebo during both excerpts, methylphenidate first followed by placebo, or placebo first followed by methylphenidate. Adults' cumulative social evaluations of the child were assessed after they viewed both video segments. Results indicated that observers combined their perceptions of the two behavior samples into composite impressions using an equal-weight averaging algorithm. Even for children whose behavior improved, adults' ratings of undercontrolled behaviors continued to meet or, in some cases exceed, research cutoff scores used to identify hyperactive children. The findings suggest that the actual behaviors of children with attention-deficit hyperactivity disorder (ADHD) play a more influential role in shaping interpersonal impressions than do perceiver social-cognitive processes such as primacy, recency, or integration biases. PMID:8126317

  11. MECHANICAL PROPERTIES OF BLENDS OF PAMAM DENDRIMERS WITH POLY(VINYL CHLORIDE) AND POLY(VINYL ACETATE)

    EPA Science Inventory

    Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonacne ...

  12. A multiphase analysis of partitioning and hazard index characteristics of siloxanes in biosolids.

    PubMed

    Surita, Sharon C; Tansel, Berrin

    2014-04-01

    Siloxanes are widely used in personal care and industrial products due to their soft texture, low surface tension, thermal stability, antimicrobial and hydrophobic properties, among other characteristics. As a result, they are released to gas phase during waste decompositions and found in biogas at landfills and digester gas at wastewater treatment facilities. The objectives of this study were to investigate the release of siloxanes in aqueous and gaseous phase as well as in biosolids in a local wastewater treatment facility. The formation reactions were estimated using first order kinetics for commonly found siloxanes (L3, D3, D4, D5 and D6) during waste decomposition. Expected concentrations and the risk factors of exposure to siloxanes were evaluated based on the initial concentrations, partitioning characteristics and persistence parameter. D4 and D5 presented the highest initial gaseous phase concentrations of 5000 and 1800 μg/m(3) respectively. Based on first order kinetics, partition coefficients and initial concentrations, the hazards potentials were largest for D4 in both liquid phase and biosolids while D6 poses the highest risk in gaseous phase. PMID:24580825

  13. 77 FR 31008 - Enforceable Consent Agreement Development for Two Cyclic Siloxanes; Solicitation of Interested...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-05-24

    .... Final Rule. 54 FR 818, January 10, 1989. 3. SEHSC. Memorandum from Karluss Thomas. Executive Director... the Dow Corning Corporation; Notice of Receipt and Availability of the MOU Data. 74 FR 38013, July 30... AGENCY Enforceable Consent Agreement Development for Two Cyclic Siloxanes; Solicitation of...

  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. 40 CFR 721.10484 - Siloxanes and Silicones, Me vinyl, hydroxy-terminated, reaction products with...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10484 Siloxanes and Silicones, Me vinyl, hydroxy-terminated, reaction products with -modified silica. (a) Chemical substance and..., hydroxy-terminated, reaction products with -modified silica. 721.10484 Section 721.10484 Protection...

  16. 40 CFR 721.10484 - Siloxanes and Silicones, Me vinyl, hydroxy-terminated, reaction products with...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.10484 Siloxanes and Silicones, Me vinyl, hydroxy-terminated, reaction products with -modified silica. (a) Chemical substance and..., hydroxy-terminated, reaction products with -modified silica. 721.10484 Section 721.10484 Protection...

  17. 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

  18. Poly(vinyl chloride) processes and products.

    PubMed Central

    Wheeler, R N

    1981-01-01

    Poly(vinyl chloride) resins are produced by four basic processes: suspension, emulsion, bulk and solution polymerization. PVC suspensions resins are usually relatively dust-free and granular with varying degrees of particle porosity. PVC emulsion resins are small particle powders containing very little free monomer. Bulk PVC resins are similar to suspension PVC resins, though the particles tend to be more porous. Solution PVC resins are smaller in particle size than suspension PVC with high porosity particles containing essentially no free monomer. The variety of PVC resin products does not lend itself to broad generalizations concerning health hazards. In studying occupational hazards the particular PVC process and the product must be considered and identified in the study. PMID:7333230

  19. Orientation of cellulose nanowhiskers in polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Kvien, I.; Oksman, K.

    2007-06-01

    The goal of this study was to align cellulose nanowhiskers in a polymer using a strong magnetic field and thereby obtain a unidirectional reinforced nanocomposite. Cellulose whiskers (2 wt. %) were incorporated in a polyvinyl alcohol matrix using solution casting with water as the solvent. The suspension was cast and the water was evaporated while a homogeneous magnetic field of 7 T was applied. Different microscopy investigations of prepared nanocomposites indicated that the cellulose whiskers were oriented perpendicular to the direction of the magnetic field. Dynamic mechanical thermal analysis further strengthened the idea of alignment because the results showed that the dynamic modulus of the nanocomposite was around 2 GPa higher at room temperature in the aligned direction compared to the transverse direction.

  20. Survey of cyclic and linear siloxanes in sediment from the Songhua River and in sewage sludge from wastewater treatment plants, Northeastern China.

    PubMed

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

    2011-02-01

    Siloxanes are used in a wide range of industrial applications, such as fuel additives, automotive polishes and waxes, and antifoaming agents, as well as in personal care products and biomedical devices. Despite the potential for environmental occurrence, few studies have reported sources and pathways of siloxanes in the environment. In this study, we determined concentrations of four cyclic siloxanes, namely, octamethylcyclotetrasiloxane (D₄), decamethylcyclopentasiloxane (D₅), dodecamethylcyclohexasiloxane (D₆), and tetradecamethylcycloheptasiloxane (D₇) as well as 13 linear siloxanes (L₄ to L₁₆), in sediments sampled from the Songhua River and in sewage sludge sampled from treatment plants that discharge wastewater into the Songhua River in northeastern China. Siloxanes were found in all of the sediment samples at total concentrations (sum of all cyclic and linear siloxanes) as high as 2050 ng/g dry weight (dw). The respective total concentration ranges for cyclic (D₄, D₅, D₆, and D₇) and linear (L₄ to L₁₆) siloxanes in sewage sludge were 602 to 2360 and 98 to 3310 ng/g dw. Cyclic siloxanes were found at greater concentrations than linear siloxanes in sediment samples. However, the summed concentrations of linear siloxanes were higher than the summed concentrations of cyclic siloxanes in sludge samples. Among cyclic siloxanes, D₇ and D₅ were the dominant compounds in both sediment and sludge. Among linear siloxanes, L₁₀ and L₁₁ together accounted for 55% of the total concentrations in sludge samples, and L₆ accounted for 30% of the total concentration in sediment samples. To our knowledge, this is the first report to document concentrations and compositions of organosiloxanes in sediments and sewage sludge from China. PMID:21072629

  1. 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

  2. The fungicidal effect of ultraviolet light on impression materials

    SciTech Connect

    Ishida, H.; Nahara, Y.; Tamamoto, M.; Hamada, T. )

    1991-04-01

    The effects of ultraviolet (UV) light on fungi and impression materials were tested. UV light (250 microW/cm2) killed most Candida organisms (10(3) cells/ml) within 5 minutes. UV light (8000 microW/cm2) killed most C. albicans (10(7) cells/ml) within 2 minutes of exposure. The effect of UV light on dimensional change and surface roughness of impression materials (irreversible hydrocolloid, agar, and silicone rubber) was tested. The results showed that neither dimensional change nor surface roughness of the impression materials were affected. The results of this study indicate that UV light disinfects impression materials that are contaminated with Candida organisms.

  3. Physicochemical studies on polyurethane/siloxane cross-linked films for hydrophobic surfaces by the sol-gel process.

    PubMed

    Seeni Meera, Kamal Mohamed; Murali Sankar, Rajavelu; Jaisankar, Sellamuthu N; Mandal, Asit Baran

    2013-03-01

    A series of castor oil based polyurethane/siloxane cross-linked films were prepared using castor oil, isophorone diisocyanate, and 3-aminopropyl trimethoxysilane by the sol-gel process. Fourier transform infrared (FT-IR) spectra reveal the cross-linking interaction between polyurethane and siloxane moieties, thereby shifting the peak position of characteristic N-H and C═O groups to higher wavenumber. (29)Si (silica) solid state nuclear magnetic resonance spectra were used to prove the formation of siloxane network linkage in the polyurethane system, thereby analyzing the Si environment present in the polyurethane/siloxane cross-linked films. The activation energy values at two stages (Tmax1 and Tmax2) for the degradation of polyurethane films were increased with increasing silane ratio. The calculated activation energy values for the higher silane ratio (1.5) are 136 and 170 kJ/mol at Tmax1 and Tmax2, respectively. From contact angle measurements, we observed that increasing siloxane cross-linking increased the hydrophobicity of the films. The optical transmittance obtained from ultraviolet-visible spectra indicated that the film samples are transparent in the region 300-800 nm. The moisture sorption/desorption isotherm curve shows a characteristic behavior of type III isotherm corresponds to hydrophobic materials. Dynamic mechanical studies show that the increase in storage modulus reveals siloxane cross-linking gives rigidity to the films. Atomic force microscopic images show that the introduction of siloxane changes the surface roughness of the polyurethane films. It is found that the siloxane cross-linking can be used to obtain hydrophobic surface films having good thermal stability and optical transmittance. PMID:23394610

  4. Effects of Music on Image Impression and Relationship between Impression and Physical Properties

    NASA Astrophysics Data System (ADS)

    Sato, Keiko; Mitsukura, Yasue

    Auditory information plays an integral role in AV media because even identical images are perceived differently when they are matched with different music. However, we now present a few studies in which the changes in subjective perceptions were analyzed on the basis of the physical properties of the perceived items. The purpose of this study is to investigate the effects of music on image impression in terms of the physical properties of images. In this paper, we first elucidate the changes in subjective impressions when the image is presented by itself and when it is presented with music. Secondly, to clarify the relation between the impression of an image or music and physical properties, we compare the different image or music perceptions with each other and also compare their respective physical properties, which include color information, structural information, and frequency characteristics. As a result, the color information of an image containing green or saturation colors and the power of the music were strongly correlated with adjectives expressing activity. Moreover, the entropy of saturation correlated with words expressing spatial extent.

  5. Downplaying Positive Impressions: Compensation Between Warmth and Competence in Impression Management

    PubMed Central

    Holoien, Deborah Son; Fiske, Susan T.

    2014-01-01

    The compensation effect demonstrates a negative relationship between the dimensions of warmth and competence in impression formation in comparative contexts. However, does compensation between warmth and competence extend to impression management? Two studies examined whether people actively downplay their warmth in order to appear competent and downplay their competence in order to appear warm. In Studies 1a and 1b, participants selected words pretested to be high or low in warmth and competence to include in an e-mail message to people they wanted to impress. As predicted, participants downplayed their competence when they wanted to appear warm (Study 1a) and downplayed their warmth when they wanted to appear competent (Study 1b). In Studies 2a and 2b, compensation also occurred when participants introduced themselves to another person, as evidenced by the questions they selected to answer about themselves, their self-reported goals, and their open-ended introductions. Compensation occurred uniquely between warmth and competence and not for other dimensions, such as healthiness (Study 2a) and political interest (Study 2b), which suggests that the compensation effect extends beyond a mere zero-sum exchange between dimensions. PMID:24550571

  6. A technique for verifying and correcting a milled polyurethane definitive cast for nonsegmental implant restoration in an edentulous jaw.

    PubMed

    Lin, Wei-Shao; Harris, Bryan T; Metz, Michael J; Morton, Dean

    2014-09-01

    This report describes a technique that uses an acrylic resin verification device and polyvinyl siloxane impression to verify and correct the analog position in a milled polyurethane definitive cast with removable periimplant soft tissue replica for a nonsegmental implant restoration in an edentulous jaw. PMID:24836533

  7. 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 kg(-1)GAC, 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

  8. 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

  9. Graphene oxide - Polyvinyl alcohol nanocomposite based electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Pawar, Pranav Bhagwan; Shukla, Shobha; Saxena, Sumit

    2016-07-01

    Supercapacitors are high capacitive energy storage devices and find applications where rapid bursts of power are required. Thus materials offering high specific capacitance are of fundamental interest in development of these electrochemical devices. Graphene oxide based nanocomposites are mechanically robust and have interesting electronic properties. These form potential electrode materials efficient for charge storage in supercapacitors. In this perspective, we investigate low cost graphene oxide based nanocomposites as electrode material for supercapacitor. Nanocomposites of graphene oxide and polyvinyl alcohol were synthesized in solution phase by integrating graphene oxide as filler in polyvinyl alcohol matrix. Structural and optical characterizations suggest the formation of graphene oxide and polyvinyl alcohol nanocomposites. These nanocomposites were found to have high specific capacitance, were cyclable, ecofriendly and economical. Our studies suggest that nanocomposites prepared by adding 0.5% wt/wt of graphene oxide in polyvinyl alcohol can be used an efficient electrode material for supercapacitors.

  10. Polyvinyl alcohol cross-linked with two aldehydes

    NASA Technical Reports Server (NTRS)

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

    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.

  11. In Situ Cross-Linking of Polyvinyl Alcohol Films

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  12. Impression Cytology of the Lid Wiper Area.

    PubMed

    Muntz, Alex; van Doorn, Kevin; Subbaraman, Lakshman N; Jones, Lyndon W

    2016-01-01

    Few reports on the cellular anatomy of the lid wiper (LW) area of the inner eyelid exist and only one report makes use of cytological methods. The optimization of a method of collecting, staining and imaging cells from the LW region using impression cytology (IC) is described in this study. Cells are collected from the inner surface of the upper eyelid of human subjects using hydrophilic polytetrafluoroethylene (PTFE) membranes, and stained with cytological dyes to reveal the presence of goblet cells, mucins, cell nuclei and various degrees of pre- and para-keratinization. Immunocytochemical dyes show cell esterase activity and compromised cell membranes by the use of a confocal scanning laser microscope. Up to 100 microscopic digital images are captured for each sample and stitched into a high-resolution, large scale image of the entire IC span. We demonstrate a higher sensitivity of IC than reported before, appropriate for identifying cellular morphologies and metabolic activity in the LW area. To our knowledge, this is the first time this selection of fluorescent dyes was used to image LW IC membranes. This protocol will be effective in future studies to reveal undocumented details of the LW area, such as assessing cellular particularities of contact lens wearers or patients with dry eye or lid wiper epitheliopathy. PMID:27584693

  13. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Resin impression tray material. 872.3670 Section 872.3670 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3670 Resin impression tray material....

  14. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Resin impression tray material. 872.3670 Section 872.3670 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3670 Resin impression tray material....

  15. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Resin impression tray material. 872.3670 Section 872.3670 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3670 Resin impression tray material....

  16. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Resin impression tray material. 872.3670 Section 872.3670 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3670 Resin impression tray material....

  17. Impression Creep Behavior of 316LN Stainless Steel

    NASA Astrophysics Data System (ADS)

    Mathew, M. D.; Naveena; Vijayanand, D.

    2013-02-01

    Impression creep tests have been carried out at 923 K on 316LN SS containing 0.07, 0.14, and 0.22 wt.% nitrogen, under different applied stress levels. It was observed that the impression creep depth versus time curves were similar to the creep curves obtained from conventional uniaxial creep tests. The impression creep curves were characterized by a loading strain and primary and secondary creep stages similar to uniaxial creep curves. The tertiary stage observed in uniaxial creep curves was absent. The steady-state impression velocity was found to increase with increasing applied stress. The equivalent steady-state creep rates calculated from impression velocities were found to be in good agreement with the steady-state creep rates obtained from conventional uniaxial creep tests. Equivalence between applied stress and steady-state impression velocity with uniaxial creep stress and steady-state creep rate, respectively, has been established based on the laws of mechanics for time-dependent plasticity. It was found that impression velocity was sensitive to the variation in nitrogen content in the steel; impression velocity decreased with increasing nitrogen content, and the results obtained in this study were in agreement with those obtained from uniaxial creep tests.

  18. Impression Management: The Web Presence of College Presidents

    ERIC Educational Resources Information Center

    Morgan, Joanne Cardin

    2013-01-01

    Leadership profile pages on organizational websites have become staged opportunities for impression management. This research uses content analysis to examine the strategies of assertive impression management used to construct the leadership Web presence of the 70 presidents of national public universities, as identified in the "US News and…

  19. A Study of Peer Tutors Using the Neurological Impress Method.

    ERIC Educational Resources Information Center

    McAllister, Elizabeth A.

    A study investigated the efficacy of using the neurological impress method in peer tutoring during reading instruction. The neurological impress reading method is a unison reading procedure in which the student and teacher or tutor read aloud simultaneously and quickly, with the student placed slightly in front of the teacher so that the teacher's…

  20. Impression Management by Association: Construction and Validation of a Scale.

    ERIC Educational Resources Information Center

    Andrews, Martha C.; Kacmar, K. Michele

    2001-01-01

    Impression management (managing associations with others to create a favorable impression) using such tactics as boasting, blurring, blaring, and burying was examined using factor and validity analyses of data from the Image Management by Association Scale. The scale satisfactorily represented the four tactics, although burying and blaring needed…

  1. Impression Management and the Control of Social Anxieties.

    ERIC Educational Resources Information Center

    Miller, Rowland S.

    Impression management refers to the concept that people engaged in interaction will attempt to control the image of themselves that others form. This provides a foundation for social interaction, giving others information about who we are and what to expect from us. A central concern of impression management is the manner in which we are evaluated…

  2. Observing and Understanding Children's Social Interactions. An Impression Management Perspective.

    ERIC Educational Resources Information Center

    Hatch, J. Amos

    1994-01-01

    Describes ways of observing and interpreting children's peer social behavior based on the impression management perspective, which focuses on the social construction of a child's individual self-concept. Suggests that teachers and caregivers can use impression management strategies to observe and promote prosocial development in young children.…

  3. Impressions of College Intructors: Stability and Change in Student Ratings

    ERIC Educational Resources Information Center

    Dudley, Kari L.

    2013-01-01

    Although the topic of stability and change in classroom impressions research is not new, there remain unanswered questions about what impressions are stable, when they are likely to change, and for whom they are likely to change over the course of a semester. My research will begin to answer those questions. My research took place in four college…

  4. Read Two Impress: An Intervention for Disfluent Readers

    ERIC Educational Resources Information Center

    Young, Chase; Rasinski, Timothy; Mohr, Kathleen A. J.

    2016-01-01

    The authors describe a research-based method to increase students' reading fluency. The method is called Read Two Impress, which is derived from the Neurological Impress Method and the method of repeated readings. The authors provide step-by-step procedures to effectively implement the reading fluency intervention. Previous research indicates that…

  5. Synthesis and solution imidization studies of soluble poly(imide siloxane) segmented copolymers

    NASA Technical Reports Server (NTRS)

    Summers, J. D.; Arnold, C. A.; Bott, R. H.; Taylor, L. T.; Ward, T. C.

    1987-01-01

    Soluble metalinked poly(imide siloxane) segmented copolymers were synthesized utilizing a THF/NMP cosolvent system. The presence of dual solvent makes it possibled to reach high molecular weight in the amid acid stage. Incorporation of siloxanes at about 10 weight percent or higher enables the materials to be fully soluble in a range of polar solvents even after imidization. Imidization may be achieved either by conventional thermal methods on cast amic acid films or in appropriate solvent/azeotroping-agent systems employing moderate temperatures. The imidization procedure has been followed by FT-IR and NMR studies. FT-IR studies show the solution imidization follows first order kinetics and proceeds to about 96 percent completion. NMR studies of the isolated products show residual amic acid may be present after solution imidization, but only at very low levels. Properties of the solution imidized materials compared well with those obtained from samples imidized as thin films.

  6. 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.

  7. Mitigating the effect of siloxanes on internal combustion engines using landfill gasses

    SciTech Connect

    Besmann, Theodore M

    2015-01-06

    A waste gas combustion method that includes providing a combustible fuel source, in which the combustible fuel source is composed of at least methane and siloxane gas. A sodium source or magnesium source is mixed with the combustible fuel source. Combustion of the siloxane gas of the combustible fuel source produces a silicon containing product. The sodium source or magnesium source reacts with the silicon containing product to provide a sodium containing glass or sodium containing silicate, or a magnesium containing silicate. By producing the sodium containing glass or sodium containing silicate, or the magnesium containing silicate, or magnesium source for precipitating particulate silica instead of hard coating, the method may reduce or eliminate the formation of silica deposits within the combustion chamber and the exhaust components of the internal combustion engine.

  8. Mitigating the effect of siloxanes on internal combustion engines using landfill gasses

    SciTech Connect

    Besmann, Theodore M

    2014-01-21

    A waste gas combustion method that includes providing a combustible fuel source, in which the combustible fuel source is composed of at least methane and siloxane gas. A sodium source or magnesium source is mixed with the combustible fuel source. Combustion of the siloxane gas of the combustible fuel source produces a silicon containing product. The sodium source or magnesium source reacts with the silicon containing product to provide a sodium containing glass or sodium containing silicate, or a magnesium containing silicate. By producing the sodium containing glass or sodium containing silicate, or the magnesium containing silicate, or magnesium source for precipitating particulate silica instead of hard coating, the method may reduce or eliminate the formation of silica deposits within the combustion chamber and the exhaust components of the internal combustion engine.

  9. Insights into siloxane removal from biogas in biotrickling filters via process mapping-based analysis.

    PubMed

    Soreanu, Gabriela

    2016-03-01

    Data process mapping using response surface methodology (RSM)-based computational techniques is performed in this study for the diagnosis of a laboratory-scale biotrickling filter applied for siloxane (i.e. octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5)) removal from biogas. A mathematical model describing the process performance (i.e. Si removal efficiency, %) was obtained as a function of key operating parameters (e.g biogas flowrate, D4 and D5 concentration). The contour plots and the response surfaces generated for the obtained objective function indicate a minimization trend in siloxane removal performance, however a maximum performance of approximately 60% Si removal efficiency was recorded. Analysis of the process mapping results provides indicators of improvement to biological system performance. PMID:26745382

  10. Using double-poured alginate impressions to fabricate bleaching trays.

    PubMed

    Haywood, V B; Powe, A

    1998-01-01

    Esthetic and diagnostic treatment often requires two casts of one arch, one for baseline and one for alterations (diagnostic wax-up, bleaching tray, occlusal analysis). The purpose of this study was to compare the accuracy of stone casts generated from a second pour of a properly handled alginate impression with first-poured casts. A maxillary dentoform was indexed with six reference spaces (#8-15, 9-2, 2-15, and incisal-to-gingival of #3, 9, 14). Irreversible hydrocolloid (Jeltrate) impressions were made in perforated steel trays by a single investigator. Impression material was spatulated for 1 minute. The seated impression and dentoform were wrapped in a damp paper towel to simulate intraoral conditions, and allowed to set for 2 minutes. Upon separation, the impression was stored in a damp towel for 5 minutes. The impression was poured in cast stone (Microstone) according to the manufacturer's instructions. The stone-filled impression was immediately rewrapped in a damp paper towel and allowed to set for 45 minutes at room temperature. Upon removal of the stone, the impression was rinsed with cold water, shaken dry, and repoured in the same manner. Ten impressions were made: the first five impressions were poured to make casts for Group A, then repoured as described above for casts for Group B. The remaining five impressions were poured once to make casts for Group C. The six spaces of each cast were measured three times in random order using a dial caliper and the space average calculated for the cast. At each space, analysis of variance showed no significant difference among Groups A, B, or C (P < 0.05). When alginate impressions that have been poured with cast stone are kept moist during stone setting and repoured within 45 minutes, two casts can be generated from one impression with the same degree of accuracy as two casts made from taking two separate impressions, providing the alginate does not tear during first cast removal. PMID:9656923

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

    PubMed

    Nayar, Sanjna; Mahadevan, R

    2015-04-01

    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

  12. Dynamic surface tension and adsorption kinetics of a siloxane dicephalic surfactant

    NASA Astrophysics Data System (ADS)

    Zhang, Dianlong; Qu, Wenshan; Li, Zhe

    2015-02-01

    The dynamic surface tension (DST) of a siloxane dicephalic surfactant was measured by using the maximum bubble pressure method. By using the classical Ward and Tordai equation, the diffusion coefficient for each bulk surfactant concentration was calculated. The results show that at the initial adsorption stage and at the end of the adsorption process, the dynamic surface tension data were all consistent with this diffusion-controlled mechanism. Their diffusion coefficient was slightly lower than that for conventional hydrocarbon surfactants.

  13. Synthesis and properties of dicationic ionic liquids containing a siloxane structural moiety

    NASA Astrophysics Data System (ADS)

    Glukhov, L. M.; Krasovskiy, V. G.; Chernikova, E. A.; Kapustin, G. I.; Kustov, L. M.; Koroteev, A. A.

    2015-12-01

    Five new ionic liquids formed by doubly charged cations containing a siloxane moiety and bis(trifluoromethylsulfonyl) imide anion are synthesized and characterized. Their thermal stability is studied by means of TGA; melting points (glass transition temperatures) and densities are measured. The temperature dependences of kinematic viscosity of the obtained ionic liquids are presented along with their approximations by the Vogel-Tammann-Fulcher equation.

  14. Effect of siloxane spacer length on organosilicon bi-quaternary ammonium amphiphiles.

    PubMed

    Hao, Chuanming; Cui, Yuezhi; Yang, Pengfei; Zhang, Huayong; Mao, Dejiang; Cui, Xiao; Li, Junying

    2015-04-01

    A series of organosilicon Bola-form bi-quaternary ammonium amphiphiles, [OH5C3(C2H5)2N+-(CH2)3-Si(CH2)3-O-(Si(CH3)2O)n-Si(CH2)3⋯(CH2)3-N+(C2H5)2C3H5O]Cl2- (SinN2Cl2, n=0, 4, 6, 8), with the same headgroups and different length of hydrophobic linkage has been synthesized. The critical micelle concentration (CMC) of each amphiphiles was determined by equilibrium surface tension. With the increased length of hydrophobic siloxane spacer, the CMC values follow the order of Si8N2Cl2siloxane spacer and its internal oxygen atom, which make the molecular stretch free. The antimicrobial property of Si4N2Cl2 is more effective than others below the concentration of CMC, while the antimicrobial property of Si8N2Cl2 is more effective above the concentration of CMC, which indicated that both the adsorbability in formation of micellar and the hydrophobicity arising from the different length of siloxane spacer are important to inhibit microbe. Moreover, their wetting ability has been characterized by contact angles on various material surfaces. It shows that the higher weight of lipophilic siloxane spacer leads to lower contact angels. PMID:25794442

  15. Neural correlates of self-deception and impression-management.

    PubMed

    Farrow, Tom F D; Burgess, Jenny; Wilkinson, Iain D; Hunter, Michael D

    2015-01-01

    Self-deception and impression-management comprise two types of deceptive, but generally socially acceptable behaviours, which are common in everyday life as well as being present in a number of psychiatric disorders. We sought to establish and dissociate the 'normal' brain substrates of self-deception and impression-management. Twenty healthy participants underwent fMRI scanning at 3T whilst completing the 'Balanced Inventory of Desirable Responding' test under two conditions: 'fake good', giving the most desirable impression possible and 'fake bad' giving an undesirable impression. Impression-management scores were more malleable to manipulation via 'faking' than self-deception scores. Response times to self-deception questions and 'fake bad' instructions were significantly longer than to impression-management questions and 'fake good' instructions respectively. Self-deception and impression-management manipulation and 'faking bad' were associated with activation of medial prefrontal cortex (mPFC) and left ventrolateral prefrontal cortex (vlPFC). Impression-management manipulation was additionally associated with activation of left dorsolateral prefrontal cortex and left posterior middle temporal gyrus. 'Faking bad' was additionally associated with activation of right vlPFC, left temporo-parietal junction and right cerebellum. There were no supra-threshold activations associated with 'faking good'. Our neuroimaging data suggest that manipulating self-deception and impression-management and more specifically 'faking bad' engages a common network comprising mPFC and left vlPFC. Shorter response times and lack of dissociable neural activations suggests that 'faking good', particularly when it comes to impression-management, may be our most practiced 'default' mode. PMID:25527112

  16. 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.

  17. Piezoresistive Properties of Polyvinyl Chloride Composites

    NASA Astrophysics Data System (ADS)

    Toprakci, Hatice Aylin Karahan

    Textile based sensors provide an interface between the user and the electronic system by converting any type of physiological or environmental signal into electrical signals. Common applications include health monitoring, rehabilitation, multimedia, and surveillance. In this research we demonstrate fabrication of piezoresistive sensors on textile fabrics through application of a screen-printed conductive nanocomposite layer of plasticized poly(vinyl chloride) (PVC), and carbon nanofiber (CNF). In order to understand the behavior of conductive plastisol, morphological, mechanical and electrical properties of composite films were investigated for different molecular weights of PVC. Homogeneous filler dispersion and good filler/polymer interphase were observed without any dominant filler orientation. Mechanical and electrical properties were found to be affected by CNF, plasticizer content and matrix molecular weight. CNFs were found to provide substantial bridging in the matrix and enhance strength. These nanostructured composite sensors were found to be sensitive under different levels of strain which can be monitored by change in electrical resistance. Finally, we demonstrate the fabrication of piezoresistive sensors on textile fabrics through application of a screen-printed conductive nanocomposite layer of conductive plastisol. Conductive plastisol was found to show good adhesion to fabric with homogeneous CNF distribution. As in composite films, samples were found to show negative piezoresistance at different levels of strain. Strain level and filler concentration were found to affect the piezoresistive behavior and sensitivity of the printed sensors.

  18. Hydrothermal carbonization of poly(vinyl chloride).

    PubMed

    Poerschmann, J; Weiner, B; Woszidlo, S; Koehler, R; Kopinke, F-D

    2015-01-01

    Poly(vinyl chloride) (PVC) was subjected to hydrothermal carbonization in subcritical water at 180-260 °C. Dehydrochlorination increased with increasing reaction temperature. The release of chlorine was almost quantitative above ∼235 °C. The fraction of organic carbon (OC) recovered in the hydrochar decreased with increasing operating temperature from 93% at 180 °C to 75% at 250 °C. A wide array of polycyclic aromatic hydrocarbons (PAHs) could be detected in the aqueous phase, but their combined concentration amounted to only ∼140 μg g(-1) PVC-substrate at 240 °C. A pathway for the formation of cyclic hydrocarbons and O-functionalized organics was proposed. Chlorinated hydrocarbons including chlorophenols could only be identified at trace levels (low ppb). Polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs) could not be detected. The sorption potential of the hydrochar turned out to be very low, in particular for polar organic pollutants. Our results provide strong evidence that hydrothermal carbonization of household organic wastes which can be tied to co-discarded PVC-plastic residues is environmentally sound regarding the formation of toxic organic products. Following these findings, hydrothermal treatment of PVC-waste beyond operating temperatures of ∼235 °C to allow complete release of organic chlorine should be further pursued. PMID:25150971

  19. Heat resistance poly(vinyl alcohol) hydrogel

    NASA Astrophysics Data System (ADS)

    Yoshii, F.; Makuuchi, K.; Darwis, D.; Iriawan, T.; Razzak, M. T.; Rosiak, Janusz M.

    1995-08-01

    Six methods were used to evaluate the heat resistance of poly(vinyl alcohol) (PVA) hydrogel prepared by a combination of electron beam irradiation and acetalization of PVA. The physical properties of the hydrogel depended on the degree of acetilization which was affected by content of water in PVA sheet of acetalization in formaldehyde solution at 60°C. It was found that the optimum water content was 20-30%. The acetalized PVA sheet gave maximum tensile strength in electron beams irradiation at 100 kGy. The tensile strength of the hydrogel film increased to 20 MPa from 14 MPa by the irradiation. Heat resistance of the hydrogel was evaluated by measuring the mechanical properties after sterilization in a steam autoclave at 121°C for 90 min. The tensile strength decreased to 10 MPa whereas the elongation at break increased to 300%. The tackiness of the hydrogel was improved by radiation grafting of acrylic acid. Wholesomeness of the hydrogel as a wound dressing was evaluated by attaching to a burn or wound of the back skin of marmots. Advantages of the hydrogel over a gauze dressing were homogeneous adhesion to the affected parts, easy removal without damage to renewed skin and slightly faster rate of reconstruction of the injured skin.

  20. Occurrence and fate of volatile siloxanes in a municipal wastewater treatment plant of Beijing, China.

    PubMed

    Xu, Lin; Shi, Yali; Cai, Yaqi

    2013-02-01

    The occurrence and fate of four cyclic and two linear volatile siloxanes were studied in a municipal Wastewater Treatment Plant (WWTP), Beijing City, China. Aqueous and sludge samples were analyzed by solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS). In the studied WWTP, four cyclic analogs (D3-D6) had significantly higher concentrations and frequencies than the two linear analogs [Octamethyltrisiloxane (L3) and Decamethyltetrasiloxane (L4)], with inputs into the WWTP ranging from 78.2 to 387.7 kg/year. Removal efficiencies of volatile cyclic siloxanes in two parallel secondary treatment processes ranged from 59.3 to 92.7%. For volatile cyclic siloxanes, relative fractions of mass loss by adsorption to sludge ranged from 8.3 to 53.0%, and their adsorption capacities were significantly affected by the dissolved organic matter. Besides adsorption, they were eliminated mainly in anaerobic units (44.4-84.3%). Through in vitro biodegradation experiments, we concluded that in the anaerobic compartments, Hexamethylcyclotrisiloxane (D3) and Dodecamethylcyclohexasiloxane (D6) were eliminated mostly by volatilization, while Octamethylcyclotetrasiloxane (D4) and Decamethylcyclopentasiloxane (D5) may be eliminated by both volatilization and degradation. Furthermore, microbe catalysis hydrolysis was identified as one of the main degradation pathways for D4 and D5 in anaerobic compartments. PMID:23182664

  1. 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

  2. 6LiF oleic acid capped nanoparticles entrapment in siloxanes for thermal neutron detection

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    The good light output of siloxane based scintillators as displayed under γ-rays and α particles has been exploited here to obtain clear and reliable response toward thermal neutrons. Sensitization towards thermal neutrons has been pursued by adding 6LiF, in form of nanoparticles. Aiming at the enhancement of compatibility between the inorganic nanoparticles and the low polarity, siloxane based surrounding medium, oleic acid-capped 6LiF nanoparticles have been synthesized by thermal decomposition of Li trifluoroacetate. Thin pellets siloxane scintillator maintained their optical transmittance up to weight load of 2% of 6Li. Thin samples with increasing 6Li concentration and thicker ones with fixed 6Li amount have been prepared and tested with several sources (α, γ-rays, moderated neutrons). Light output as high as 80% of EJ212 under α irradiation was measured with thin samples, and negligible changes have been observed as a result of 6LiF addition. In case of thick samples, severe light loss has been observed, as induced by opacity. Nevertheless, thermal neutrons detection has been assessed and the data have been compared with GS20, based on Li glass, taken as a reference material.

  3. Differences in volatile methyl siloxane (VMS) profiles in biogas from landfills and anaerobic digesters and energetics of VMS transformations

    SciTech Connect

    Tansel, Berrin Surita, Sharon C.

    2014-11-15

    Highlights: • In the digester gas, D4 and D5 comprised the 62% and 27% if siloxanes, respectively. • In landfill gas, the bulk of siloxanes were TMSOH (58%) followed by D4 (17%). • Methane utilization may be a possible mechanism for TMSOH formation in the landfills. • The geometric configurations of D4 and D5 molecules make them very stable. - Abstract: The objectives of this study were to compare the types and levels of volatile methyl siloxanes (VMS) present in biogas generated in the anaerobic digesters and landfills, evaluate the energetics of siloxane transformations under anaerobic conditions, compare the conditions in anaerobic digesters and municipal solid waste (MSW) landfills which result in differences in siloxane compositions. Biogas samples were collected at the South District Wastewater Treatment Plant and South Dade Landfill in Miami, Florida. In the digester gas, D4 and D5 comprised the bulk of total siloxanes (62% and 27%, respectively) whereas in the landfill gas, the bulk of siloxanes were trimethylsilanol (TMSOH) (58%) followed by D4 (17%). Presence of high levels of TMSOH in the landfill gas indicates that methane utilization may be a possible reaction mechanism for TMSOH formation. The free energy change for transformation of D5 and D4 to TMSOH either by hydrogen or methane utilization are thermodynamically favorable. Either hydrogen or methane should be present at relatively high concentrations for TMSOH formation which explains the high levels present in the landfill gas. The high bond energy and bond distance of the Si–O bond, in view of the atomic sizes of Si and O atoms, indicate that Si atoms can provide a barrier, making it difficult to break the Si–O bonds especially for molecules with specific geometric configurations such as D4 and D5 where oxygen atoms are positioned inside the frame formed by the large Si atoms which are surrounded by the methyl groups.

  4. 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

  5. Social Relevance Enhances Memory for Impressions in Older Adults

    PubMed Central

    Cassidy, Brittany S.; Gutchess, Angela H.

    2012-01-01

    Previous research has demonstrated that older adults have difficulty retrieving contextual material over items alone. Recent research suggests this deficit can be reduced by adding emotional context, allowing for the possibility that memory for social impressions may show less age-related decline than memory for other types of contextual information. Two studies investigated how orienting to social or self-relevant aspects of information contributed to the learning and retrieval of impressions in young and older adults. Participants encoded impressions of others in conditions varying in the use of self-reference (Experiment 1) and interpersonal meaningfulness (Experiment 2), and completed memory tasks requiring the retrieval of specific traits. For both experiments, age groups remembered similar numbers of impressions. In Experiment 1, using more self-relevant encoding contexts increased memory for impressions over orienting to stimuli in a non-social way, regardless of age. In Experiment 2, older adults had enhanced memory for impressions presented in an interpersonally meaningful relative to a personally irrelevant way, whereas young adults were unaffected by this manipulation. The results provide evidence that increasing social relevance ameliorates age differences in memory for impressions, and enhances older adults’ ability to successfully retrieve contextual information. PMID:22364168

  6. 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

  7. Strategies for managing impressions of racial identity in the workplace.

    PubMed

    Roberts, Laura Morgan; Cha, Sandra E; Kim, Sung Soo

    2014-10-01

    This article deepens understanding of the workplace experiences of racial minorities by investigating racial identity-based impression management (RIM) by Asian American journalists. Racial centrality, directly or indirectly, predicted the use of 4 RIM strategies (avoidance, enhancement, affiliation, and racial humor). Professional centrality also predicted strategy use, which was related to life satisfaction and perceived career success. By shedding light on proactive strategies that individuals use to influence colleagues' impressions of their racial identity, we contribute to research on diversity in organizations, impression management, and racial identity. PMID:25090148

  8. Consumer impressions of Tender Select beef.

    PubMed

    Shackelford, S D; Wheeler, T L; Meade, M K; Reagan, J O; Byrnes, B L; Koohmaraie, M

    2001-10-01

    With the recent development of technology to classify beef for tenderness, it is now possible for packers and retailers to market brands of beef known to be consistently tender. The present experiment was conducted to determine consumer impressions of Tender Select, a model beef brand comprised of cuts from tender U.S. Select carcasses. A telephone survey was conducted in metropolitan Denver, CO, to recruit consumers (n = 1,036) for this study. Consumers who met minimal limits for household income, age, and beef consumption were invited to participate in a beef shopping and usage study in a local supermarket. Point-of-purchase material was developed that described Tender Select as "the only steak guaranteed tender and lean." When shown a copy of the Tender Select concept card, 89% of participating consumers (n = 759) indicated that they would definitely or probably buy that product. Of those consumers that said they would buy the product, 35% indicated that their purchases of Tender Select would be in addition to their current fresh meat purchases. Most consumers (54.1%) indicated that if Tender Select was available at their grocery store, 1 or 2 of their next 10 purchases of beef cuts would be Tender Select. Sixty-five percent of consumers indicated that if a grocery store carried a line of beef cuts guaranteed to be tender, they would buy all of their beef at that store. Both strip loins from 104 U.S. Select beef carcasses, representing a broad range (8.7 to 43.4 kg; CV = 42%) in slice shear force (SSF) at 14 d postmortem, were used to determine the effect of SSF classification on consumer satisfaction and the correlation among trained sensory panel descriptive attribute ratings and in-home consumer ratings of beef longissimus steaks. Both trained sensory panelists and consumers rated low-SSF steaks higher than the high-SSF steaks for all traits (P < 0.001). All consumer traits (like, tenderness, juiciness, flavor like, flavor amount, and overall satisfaction

  9. 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 (86.1-157.5mg m(-3)) and downstream (2.2-4.3mg m(-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 1.5mg m(-3) (47.8%). Importantly, a limit of detection of 3.2mg m(-3) was identified which is below the recommended siloxane limit and evidences the applicability of on-line FTIR for this application. PMID:25966392

  10. Indirect method of base adaptation against supporting element of tooth root for a partial overdenture prosthesis.

    PubMed

    Oh, Won-suk; Park, Ju-mi

    2014-08-01

    The base of a partial overdenture prosthesis should be fitted intraorally against the supporting element of a tooth root. Chairside relining is a common method; however, an autopolymerizing acrylic resin presents high porosity when polymerized intraorally. This article describes an indirect method where an impression is made with a silicone occlusion registration material to create a replica of the supporting elements of the residual ridge and the tooth root in a high-viscosity polyvinyl siloxane impression material. PMID:24412183

  11. Persons who most impress gifted youth: a replication.

    PubMed

    Karnes, F A; McGinnis, J C

    1994-06-01

    A replication of a study of the persons who most impressed gifted youth was conducted with 95 students enrolled in a summer residential program for the gifted. Students were asked to indicate the person who most impressed them and to include the reason(s) for choosing that person. The most frequently chosen category of individuals was family members (61.1%), then a tie between persons in the world of arts and culture and persons doing a specific job (8.4%), another tie between comrades and sports stars (6.3%), followed by political or historical figures (4.2%), themselves (3.2%), and moral and religious personalities (2.1%). Consistent with the 1982 study by Karnes and Lee, most impressive to these students were family members and least impressive moral and religious personalities. PMID:8058865

  12. 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

  13. Managing Impression Formation in Computer-Mediated Communication.

    ERIC Educational Resources Information Center

    Liu, Yuliang; Ginther, Dean

    2001-01-01

    Offers suggestions for online instructors regarding verbal and nonverbal impression management. The recommendations should facilitate computer mediated teacher-student or manager-client interactions and help develop constructive relationships that promote learning and productivity. (EV)

  14. Simplified custom impression post for implant-supported restorations.

    PubMed

    Patras, Michael; Martin, William

    2016-05-01

    The esthetic outcome of an implant-supported restoration is greatly influenced by the relationship between the contours of the definitive prosthesis and the periimplant tissues. In this clinical technique, an implant analog holder and autopolymerizing acrylic resin were used to accurately register the soft-tissue transition zone created by the interim restoration and transfer it to the impression post during the definitive impression. PMID:26774317

  15. Auditory and visual spatial impression: Recent studies of three auditoria

    NASA Astrophysics Data System (ADS)

    Nguyen, Andy; Cabrera, Densil

    2004-10-01

    Auditory spatial impression is widely studied for its contribution to auditorium acoustical quality. By contrast, visual spatial impression in auditoria has received relatively little attention in formal studies. This paper reports results from a series of experiments investigating the auditory and visual spatial impression of concert auditoria. For auditory stimuli, a fragment of an anechoic recording of orchestral music was convolved with calibrated binaural impulse responses, which had been made with the dummy head microphone at a wide range of positions in three auditoria and the sound source on the stage. For visual stimuli, greyscale photographs were used, taken at the same positions in the three auditoria, with a visual target on the stage. Subjective experiments were conducted with auditory stimuli alone, visual stimuli alone, and visual and auditory stimuli combined. In these experiments, subjects rated apparent source width, listener envelopment, intimacy and source distance (auditory stimuli), and spaciousness, envelopment, stage dominance, intimacy and target distance (visual stimuli). Results show target distance to be of primary importance in auditory and visual spatial impression-thereby providing a basis for covariance between some attributes of auditory and visual spatial impression. Nevertheless, some attributes of spatial impression diverge between the senses.

  16. Comparison of two impression techniques for auricular prosthesis: pilot study.

    PubMed

    Mohamed, Kasim; Mani, U M; Seenivasan, M K; Vaidhyanathan, A K; Veeravalli, P T

    2013-01-01

    The purpose of this article was to compare the accuracy of a new impression technique, the triple-layer impression technique (TLIT), with the conventional impression technique (CIT) to fabricate an auricular prosthesis. Fifteen male subjects (aged 22-45 yr) were selected. Ten markings were made on the subject's ear (super aurale [sa], sub aurale [sba], pre aurale [pra], post aurale [poa], A, A1, B, B1, C, and C1) and five measurements (sa-sba, pra-poa, A-A1, B-B1, and C-C1) were made. Custom-made trays were used to record impression in CIT and TLIT. Impressions were made using alginate, and models were cast with type IV gypsum product. Markings were transferred on the cast. Measurements were rechecked on the models. Distribution analysis of difference in measurements between the two impression techniques and the subject's actual values was evaluated. Sign test was used to analyze the statistical significance. Statistically significant differences were found in measurements A-A1, B-B1, and C-C1 between the two techniques when compared with the subject's actual dimensions (p < 0.01). TLIT was found to produce accurate models when compared with CIT. The TLIT used in the study was cost effective, less technique sensitive, and tailor made to reduce chairside orientation time during wax try-in appointments for rehabilitating patients, especially those with unilateral auricular defects. PMID:24458893

  17. Polyvinyl alcohol battery separator containing inert filler. [alkaline batteries

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A cross-linked polyvinyl alcohol battery separator is disclosed. A particulate filler, inert to alkaline electrolyte of an alkaline battery, is incorporated in the separator in an amount of 1-20% by weight, based on the weight of the polyvinyl alcohol, and is dispersed throughout the product. Incorporation of the filler enhances performance and increases cycle life of alkaline batteries when compared with batteries containing a similar separator not containing filler. Suitable fillers include titanates, silicates, zirconates, aluminates, wood floor, lignin, and titania. Particle size is not greater than about 50 microns.

  18. Complexes of polyvinyl alcohol with insoluble inorganic compounds

    NASA Astrophysics Data System (ADS)

    Prosanov, I. Yu.; Bulina, N. V.; Gerasimov, K. B.

    2013-10-01

    Hybrid materials of polyvinyl alcohol-hydroxides/oxides of Be, Mg, Zn, Cd, B, Al, Cr, and Fe have been obtained. The studies have been carried out by the methods of optical spectroscopy, X-ray diffraction, and synchronous thermal analysis. Interpretation of experimental data is presented, presuming that, in systems with zinc, boron, aluminum, chromium, and iron hydroxides/oxides, interpolymeric complexes of polyvinyl alcohol with corresponding polymeric inorganic compounds are formed. They belong to a new class of materials with unusual structure containing chains of inorganic polymers isolated in the organic matrix.

  19. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., may not exceed: (i) 2000 ppm for polyvinyl chloride dispersion resins, excluding latex resins; (ii... exceed: (i) 2 g/kg (4 lb/ton) product from the stripper(s) for dispersion polyvinyl chloride resins... dispersion polyvinyl chloride resins, excluding latex resins, with the product determined on a dry...

  20. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., may not exceed: (i) 2000 ppm for polyvinyl chloride dispersion resins, excluding latex resins; (ii... exceed: (i) 2 g/kg (4 lb/ton) product from the stripper(s) for dispersion polyvinyl chloride resins... dispersion polyvinyl chloride resins, excluding latex resins, with the product determined on a dry...

  1. Formulation/cure technology for ultrahigh molecular weight silphenylene-siloxane polymers

    NASA Technical Reports Server (NTRS)

    Hundley, N. H.; Patterson, W. J.

    1985-01-01

    Molecular weights above one million were achieved for methylvinylsilphenylene-siloxane terpolymers using a two-stage polymerization technique which was successfully scaled up to 200 grams. The resulting polymer was vulcanized by two different formulations and compared to an identically formulated commercial methylvinyl silicone on the basis of ultimate strength, Young's modulus, percent elongation at failure, and tear strength. Relative thermal/oxidative stabilities of the elastomers were assessed by gradient and isothermal thermogravimetric analyses performed in both air and nitrogen. The experimental elastomer exhibited enhanced thermal/oxidative stability and possed equivalent or superior mechanical properties. The effect of variations in prepolymer molecular weight on mechanical properties was also investigated.

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

    DOEpatents

    Babcock, Walter C.; Friesen, Dwayne T.

    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.

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

    DOEpatents

    Babcock, W.C.; Friesen, D.T.

    1988-11-01

    Novel semipermeable 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.

  4. 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.

  5. NHC-catalyzed dehydrogenative self-coupling of diphenylsilane: A facile synthesis of octaphenylcyclotetra(siloxane)

    PubMed Central

    Albright, Abigail; Gawley, Robert E.

    2011-01-01

    A unique application of the CuIPr N-heterocyclic carbene (NHC) to the dehydrogenative self-coupling of diphenylsilane has been discovered. This transformation is carried out open to air at room temperature, yielding octaphenylcyclotetra(siloxane) quantitatively in one hour. This preparation constitutes a significant improvement over existing methods for the preparation of this compound and demonstrates a novel mode of reactivity for CuIPr. The diphenylsilanone tetramer is the precursor to a number of industrially significant polymers. PMID:22058577

  6. A survey of cyclic and linear siloxanes in indoor dust and their implications for human exposures in twelve countries.

    PubMed

    Tran, Tri Manh; Abualnaja, Khalid O; Asimakopoulos, Alexandros G; Covaci, Adrian; Gevao, Bondi; Johnson-Restrepo, Boris; Kumosani, Taha A; Malarvannan, Govindan; Minh, Tu Binh; Moon, Hyo-Bang; Nakata, Haruhiko; Sinha, Ravindra K; Kannan, Kurunthachalam

    2015-05-01

    Siloxanes are used widely in a variety of consumer products, including cosmetics, personal care products, medical and electrical devices, cookware, and building materials. Nevertheless, little is known on the occurrence of siloxanes in indoor dust. In this survey, five cyclic (D3-D7) and 11 linear (L4-L14) siloxanes were determined in 310 indoor dust samples collected from 12 countries. Dust samples collected from Greece contained the highest concentrations of total cyclic siloxanes (TCSi), ranging from 118 to 25,100ng/g (median: 1380), and total linear siloxanes (TLSi), ranging from 129 to 4990ng/g (median: 772). The median total siloxane (TSi) concentrations in dust samples from 12 countries were in the following decreasing order: Greece (2970ng/g), Kuwait (2400), South Korea (1810), Japan (1500), the USA (1220), China (1070), Romania (538), Colombia (230), Vietnam (206), Saudi Arabia (132), India (116), and Pakistan (68.3). TLSi concentrations as high as 42,800ng/g (Kuwait) and TCSi concentrations as high as 25,000ng/g (Greece) were found in indoor dust samples. Among the 16 siloxanes determined, decamethylcyclopentasiloxane (D5) was found at the highest concentration in dust samples from all countries, except for Japan and South Korea, with a predominance of L11; Kuwait, with L10; and Pakistan and Romania, with L12. The composition profiles of 16 siloxanes in dust samples varied by country. TCSi accounted for a major proportion of TSi concentrations in dust collected from Colombia (90%), India (80%) and Saudi Arabia (70%), whereas TLSi predominated in samples collected from Japan (89%), Kuwait (85%), and South Korea (78%). Based on the measured median TSi concentrations in indoor dust, we estimated human exposure doses through indoor dust ingestion for various age groups. The exposure doses ranged from 0.27 to 11.9ng/kg-bw/d for toddlers and 0.06 to 2.48ng/kg-bw/d for adults. PMID:25749636

  7. 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

  8. 75 FR 15726 - Polyvinyl Alcohol From Taiwan; Determination

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-30

    ... September 15, 2004 (69 FR 55653). The conference was held in Washington, DC, on September 28, 2004, and all....\\3\\ Notice of that determination was published on October 29, 2004. 69 FR 63177. The Commission... COMMISSION Polyvinyl Alcohol From Taiwan; Determination On the basis of the record \\1\\ developed in...

  9. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b)...

  10. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b)...