Sample records for polyvinyl siloxane impression

  1. Evaluation of dimensional stability and accuracy of autoclavable polyvinyl siloxane impression material.

    PubMed

    Reddy, Subash M; Vijitha, D; Karthikeyan, S; Balasubramanian, R; Satish, A

    2013-12-01

    Dimensionally stable autoclavable impressions will be effective in controlling the cross-infection and contamination caused by patient's saliva and other oral secretions. The accuracy of newly introduced autoclavable polyvinyl siloxane impression material was assessed for its dimensional stability and accuracy. A standard metal model (Dentoform, U-501, Columbia) was customised for impression making. The impressions were made using the newly introduced polyvinyl siloxane impression materials (AFFINIS, Coltene/Whaledent AG, 9450 Alstalten, Switzerland). Fifty impressions were made and were divided into two groups A and B of 25 each. Group A was the control sample (non-autoclaved impressions) and group B was the test sample (autoclaved impressions), which was subjected to the steam autoclave procedure at 134 °C for 18 min, casts were poured in type IV gypsum products. The customised metal model, casts obtained from control and test group were subjected to laboratory evaluation with help of a travelling microscope (×10 magnification), and digital vernier calliper (0.01 mm/10 ?m accuracy). Data analysis was done using one-way ANOVA and One-Sample t test to evaluate the overall accuracy (P < 0.005). As a result, there was an average reduction of 0.016 ?m in overall dimension between the test and the control group when compared with the master model, which is not statistically or clinically significant. The newly introduced polyvinyl siloxane impression material is accurate and dimensional stable for clinical use when steam autoclaved at 134 °C for 18 min. PMID:24431790

  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-?m 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 most dimensionally accurate impression methods in terms of resultant casts. How to cite this article: Dugal R, Railkar B, Musani S. 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. J Int Oral Health 2013;5(5):85-94. PMID:24324310

  3. “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

  4. Long-term dimensional stability and reproduction of surface detail of four polyvinyl siloxane duplicating materials

    Microsoft Academic Search

    Ravi Pant; Andrzej S. Juszczyk; Robert K. F. Clark; David R. Radford

    2008-01-01

    ObjectivesDuplicating materials must routinely accurately reproduce the details of dental casts and thus contribute significantly to the close adaptation and success of a removable prosthesis or fixed indirect restoration. It is important to establish the long-term dimensional stability of polyvinyl siloxane materials (PVS) as they are widely used in dental technology and over the duration of a course of treatment,

  5. 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

  6. 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 (? = 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.

  7. Three-dimensional assessment of dental casts' occlusal surfaces using two impression materials.

    PubMed

    Tarawneh, F M; Panos, P G; Athanasiou, A E

    2008-11-01

    The aim of this study was to assess by means of a three-dimensional computed tomography scanning system the occlusal surface characteristics of dental casts made using two different impression materials. Alginate and polyvinyl siloxane impressions were taken of 20 dental students resulting in 40 dental casts. The casts were paired for each student separately so that each pair consisted of an alginate poured cast and a polyvinyl siloxane poured out cast. The casts were scanned using FlashCT scanner and for each cast, a three-dimensional digital image was obtained. The digitized casts were processed using the three-dimensional imaging software Geomagic Studio 9. A total of 464 paired teeth were digitally separated and superimposed. For each tooth, two measurements were obtained corresponding to the two different impression materials used. The two sets of volumes for all digitally separated teeth were compared and analysed using the Wilcoxon signed test. Larger volume measurements were obtained for teeth separated from alginate poured out casts than from their corresponding ones from polyvinyl siloxane casts (P = 0.005). When the teeth were divided into the groups of incisors, canines and premolars/molars, only the last one exhibited significant difference (P = 0.00). The mean difference between the volumes measured for all 464 teeth separated was 0.041 mm(3) (+/-0.33). The occlusal surfaces of teeth appear differently in dental casts depending on the impression materials used. Impressions of dental casts should be utilized with caution in relation to their research application and in reference with dental wear studies. PMID:18482343

  8. 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

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

    PubMed

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

    2014-12-01

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

  10. 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.

  11. SILOXANE-PHOSPHONATE POLYMERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The polymerization of di- and tri-alkoxysilanes using conventional sol-gel techniques produces two and three-dimensional siloxane networks. The hydrolysis and condensation result in the formation of an alcohol under mild conditions which can be removed under reduced pressure and moderate temperature...

  12. Siloxane-grafted membranes

    DOEpatents

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

    1989-01-01

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

  13. 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…

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

    NASA Astrophysics Data System (ADS)

    Subeihi, Haitham

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

  15. 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).

  16. 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.

  17. 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

  18. First Impressions Experiment

    NSDL National Science Digital Library

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

  19. Preservation of limestone material culture with siloxanes

    E-print Network

    Miller, Ann Elizabeth

    2001-01-01

    to determine the effectiveness of consolidants on limestone. Second, several siloxane/alkoxysilane mixtures and alkoxysilanes that were studied did protect limestone from water absorption, and accelerated weathering. There is still more data needed before a...

  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. Siloxane treatment by adsorption into porous materials

    Microsoft Academic Search

    D. Ricaurte Ortega; A. Subrenat

    2009-01-01

    Siloxanes are widely used in different applications: health care, dry cleaning, household products, paints and coatings, paper, personal care, for example. This explains their prevalence in the environment. Because of their volatile nature, most of the time they are dispersed in the atmosphere, but they can also be present in the slurry from landfills. During anaerobic digestion, when the temperature

  2. Polyazomethines derived from polynuclear dihydroxyquinones and siloxane diamines

    Microsoft Academic Search

    Angelica Vlad; Maria Cazacu; Grigore Munteanu; Anton Airinei; Petru Budrugeac

    2008-01-01

    New polyazomethines have been synthesized based on polynuclear dihydroxy quinones (5,8-dihydroxy-1,4-naphthoquinone and 1,4-dihydroxyanthraquinone) and siloxane diamines differing by the siloxane sequence length (1,3-bis(3-aminopropyl)tetramethyldisiloxane and ?,?-bis(3-aminopropyl)oligodimethylsiloxane having about 12 siloxane units\\/sequence). The structures were verified by spectral analyses. Solubility tests, GPC and viscosity measurements were performed. Some properties of the resulted polymers were investigated by thermal (TGA and DSC), electrical, spectral

  3. 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.

  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. Some impressions of the department

    E-print Network

    Sorkin, Michael David

    1984-01-01

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

  6. Energy use of biogas hampered by the presence of siloxanes

    Microsoft Academic Search

    Raf Dewil; Lise Appels; Jan Baeyens

    2006-01-01

    Siloxanes are widely used in industrial processes and consumer products. Some of them reach the wastewater. Siloxanes are not decomposed in the activated sludge process and partly concentrate in the sludge. During anaerobic digestion of the sludge, they volatilise into the formed biogas. Combustion of silicon containing gases, e.g., when producing electricity, produces, however, the abrasive microcrystalline silica that has

  7. Synthesis and characterization of thiol-ene functionalized siloxanes and evaluation of their polymerization kinetics, network properties, and dental applications

    NASA Astrophysics Data System (ADS)

    Cole, Megan A.

    We explored formation-structure-property relationships in thiol-ene functionalized oligosiloxanes to create crosslinked networks. Specifically, nine oligomers were synthesized, three with thiol-functional silane repeats and three with allyl-functional silane repeats. Structural variations in each oligomer were systematically induced through the incorporation of non-reactive repeats bearing either diphenyl or di-n-octyl moieties, and the oligomer molecular weight was limited by the presence of monofunctional silane condensation species. The molecular weights and chain compositions of all oligomers were ascertained and subsequently used in the evaluation of network properties formed upon photopolymerization of thiol- and ene-functional reactants. Polymerization kinetics of the thiol-ene functionalized siloxanes were also investigated using photoinitiation owing to the spatial and temporal control afforded by this technique. In particular, the effects of the viscosity of the ene-functionalized oligomer and the degree of thiol functionalization on the observed polymerization rate were determined. Results showed that the speed of polymerization varied with changes to the rate-limiting step, which was heavily influenced by neighboring non-reactive functionalities. Moreover, the thiol-ene reaction was found to exhibity unimolecular termination exclusively in siloxane-based systems. Proposed use of the thiol-ene functionalized siloxane system as a dental impression material necessitated the development of a redox initiation scheme. Evaluation of the benzoylperoxide/dimethyl-p-toluidine redox pair in traditional systems showed bulk thiol-ene polymerizations comparable to photoinitiation with the added advantage of uninhibited depth control, as also demonstrated in small molecule thiol-ene coupling reactions initiated by this same redox system. Application of the redox pair to the siloxane system allowed for the viscoelastic properties as well as the feature replication abilities to be compared against commercial impression materials. The siloxane system was found to match the commercial material for strain recovery and stress relaxation and exceed its replication properties though it would require greater overall strength to function adequately in the clinical setting.

  8. SOURCE ASSESSMENT: POLYVINYL CHLORIDE

    EPA Science Inventory

    This report summarizes data on air emissions from the polyvinyl chloride (PVC) industry. PVC is manufactured by 20 companies at 35 plants. Each plant uses one or more of four possible polymerization processes: (1) suspension polymerization, (2) emulsion polymerization, (3) bulk p...

  9. 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.

  10. Issues in handling impression materials.

    PubMed

    Giordano, R

    2000-01-01

    Implant restorations require extreme accuracy since the implants are rigidly fixed. Although impression materials can be highly accurate, small inaccuracies are acceptable because the periodontal ligament allows for tooth movement. This luxury is not available with implants. A problem is the rotation of direct impression copings and distortion of interabutment positions in the master cast. Wee investigated the amount of torque required to displace a coping in eight impression material groups and the positional accuracy of the materials. The initial examination of torque narrowed the acceptable materials to a medium viscosity polyether, a high viscosity addition silicone, and a medium viscosity polysulfide-condensation silicones were eliminated. The results showed that the polyether and addition silicone produced casts with minimal distortion. Finally, it always is prudent to read the manufacturer's recommendations for use of impression materials. Catalyst-to-base ratios vary, as do working and setting times, depending on exact compositions. Impression materials also have various degrees of compatibility with stone, particularly the hydrocolloids, and it is advisable to use the recommended stone. Adhesives should be applied at least 15 minutes prior to loading the impression material. If at all possible, use of a rigid tray is recommended and impressions should be poured in the dental office; this minimizes the error produced at the beginning of the fabrication process. Elimination of errors early in fabrication of a prosthesis help prevent their magnification and result in a better-fitting restoration, requiring minimal adjustment in the end. PMID:12004656

  11. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...hollow copper tube intended to take an impression of a single tooth. The hollow tube is filled with impression material. One...material, such as wax, the remaining end is slipped over the tooth to make the impression. (b) Classification....

  12. 21 CFR 872.6570 - Impression tube.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...hollow copper tube intended to take an impression of a single tooth. The hollow tube is filled with impression material. One...material, such as wax, the remaining end is slipped over the tooth to make the impression. (b) Classification....

  13. Ecotoxicity of siloxane D5 in soil.

    PubMed

    Velicogna, Jessica; Ritchie, Ellyn; Princz, Juliska; Lessard, Marie-Eve; Scroggins, Rick

    2012-03-01

    Decamethylcyclopentasiloxane (D5) is a cyclic volatile methyl siloxane (cVMS) commonly found in commercially available products. D5 is expected to enter the terrestrial environment through the deposit of biosolids from sewage treatment plants onto agricultural fields for nutrient enrichment. Little to no information currently exists as to the risks of D5 to the terrestrial environment. In order to evaluate the potential risk to terrestrial organisms, the toxicity of a D5 contaminated biosolid in an agricultural soil was assessed with a battery of standardized soil toxicity tests. D5 was spiked into a surrogate biosolid and then mixed with a sandy loam soil to create test concentrations ranging from 0 to 4074 mg kg(-1). Plant (Hordeum vulgare (barley) and Trifolium pratense (red clover)) and soil invertebrates (Eisenia andrei (earthworm) and Folsomia candida (springtail)) toxicity tests were completed to assess for lethal and sub-lethal effects. Plant testing evaluated the effects on seedling emergence, shoot and root length, and shoot and root dry mass. Invertebrate test endpoints included adult lethality, juvenile production, and individual juvenile dry mass (earthworms only). Soil samples were collected over time to confirm test concentrations and evaluate the loss of chemical over the duration of a test. The toxicity of the D5 was species and endpoint dependent, such that no significant adverse effects were observed for T. pratense or E. andrei test endpoints, however, toxicity was observed for H. vulgare plant growth and F. candida survival and reproduction. Chemical losses of up to 50% were observed throughout the tests, most significantly at high concentrations. PMID:22197313

  14. Occurrence of cyclic and linear siloxanes in indoor dust from China, and implications for human exposures.

    PubMed

    Lu, Yan; Yuan, Tao; Yun, Se Hun; Wang, Wenhua; Wu, Qian; Kannan, Kurunthachalam

    2010-08-15

    Siloxanes are used in a wide variety of personal-care and other consumer products. Although there is clearly a potential for contamination of indoor dust with siloxanes, reports of occurrence of siloxanes in indoor dust were not available, prior to the present study. Here, we have determined the concentrations and profiles of four cyclic siloxanes, octamethylcyclotetrasiloxane (D(4)), decamethylcyclopentasiloxane (D(5)), dodecamethylcyclohexasiloxane (D(6)), and tetradecamethylcycloheptasiloxane (D(7)), as well as 11 linear siloxanes, from L(4)-L(14), in 100 dust samples collected in China. Cyclic and linear siloxanes were found in all dust samples, with the linear siloxanes L(9)-L(14) being the predominant compounds. Concentrations of total siloxanes in dust ranged from 21.5 to 21,000 (mean: 1540 +/- 2850) ng g(-1). The highest concentration of the individual linear siloxanes, L(9)-L(14), ranged between 2680 and 6170 ng g(-1). Concentrations of total linear siloxanes (TLS) were 1-2 orders of magnitude higher than concentrations of total cyclic siloxanes (TCS), in all indoor dust samples. Siloxane concentrations in dust were associated with the number of electrical/electronic appliances, number of occupants, and smokers living in the house. Based on the measured siloxane concentrations and on estimated daily ingestion rates of dust by toddlers and adults, we calculated the daily intake of siloxanes. For adults, daily exposure to total siloxanes, based on an average dust intake rate and median exposure concentration, was calculated to be 15.9 ng day(-1); the corresponding value for toddlers was 32.8 ng d(-1). PMID:20704203

  15. Methyl modified siloxane melting gels for hydrophobic films

    Microsoft Academic Search

    Andrei Jitianu; John Doyle; Glenn Amatucci; Lisa C. Klein

    2010-01-01

    Hybrid melting gels were prepared by a sol–gel process, starting with a mono-substituted siloxane and a di-substituted siloxane.\\u000a Methyl-modified melting gels were prepared using (a) methyltriethoxysilane (MTES) with dimethyldiethoxysilane (DMDES) and\\u000a (b) methyltrimethoxysilane (MTMS) together with dimethyldimethoxysilane (DMDMS). The gels with MTES–DMDES were prepared with\\u000a concentrations between 50–50 and 75–25 mol%. The gels with MTMS–DMDMS were prepared with concentrations between 50–50

  16. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    . (1) The chemical substance identified generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  17. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    . (1) The chemical substance identified generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  18. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    . (1) The chemical substance identified generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  19. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    . (1) The chemical substance identified generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  20. 40 CFR 721.10119 - Siloxane modified silica nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    . (1) The chemical substance identified generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  1. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    . (1) The chemical substance identified generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  2. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    . (1) The chemical substance identified generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

  3. 40 CFR 721.10120 - Siloxane modified alumina nanoparticles (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    (1) The chemical substance identified generically as siloxane modified alumina nanoparticles (PMN P-05-687) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

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

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    (1) The chemical substance identified generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    . (1) The chemical substance identified generically as siloxane modified silica nanoparticles (PMN P-05-673) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this section. (2) The significant new uses...

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

    NASA Technical Reports Server (NTRS)

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

    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. Impression recovery of amorphous polymers

    Microsoft Academic Search

    Fuqian Yang; Shengliang Zhang; J. C. M. Li

    1997-01-01

    The impression made by a loaded cylindrical flat-end punch on a polymer surface was observed to disappear with time at the\\u000a same temperature after the load was removed. The depth-time relation appeared to obey second order kinetics. The temperature\\u000a dependence of the rate constant shows two consecutive processes with activation energies, 906 kJ\\/mole (between 143 and 147°C)\\u000a and 91 kJ\\/mole

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

    PubMed

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

    2014-11-11

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

  9. 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

  10. Deciphering indented impressions on plastic.

    PubMed

    Brown, Sharon; Klein, Asne; Chaikovsky, Alan

    2003-07-01

    The questioned document laboratory is often called upon to decipher writing that has been erased, obliterated, or that has faded. In cases like these, the original writing is no longer legible to the naked eye, but may be enhanced using various light sources. Certain remnants of the ink's components absorb into the substrate's fibers and can be visualized, usually as luminescence or absorbance. A case is described here that involved the theft of a credit card. An empty plastic credit card holder was found in the possession of a suspect, and as submitted for examination. Indented impressions could be discerned on its clear plastic window and presumably originated from the credit card that had been held in the envelope. These indented impressions were deciphered in the hope that they would reveal enough details from the credit card to establish a connection between the plastic envelope and the stolen credit card. With methods generally utilized in the toolmarks and materials laboratory and the photography laboratory of the Israel Police, most of the indented impressions on the plastic were deciphered and a connection between the plastic envelope and the stolen credit card was demonstrated. PMID:12877309

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

    PubMed Central

    2015-01-01

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

  12. Recyclable polystyrene-supported siloxane-transfer agent for palladium-catalyzed cross-coupling reactions.

    PubMed

    Nguyen, Minh H; Smith, Amos B

    2014-04-01

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

  13. 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.

  14. 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.

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

    PubMed

    Gislon, P; Galli, S; Monteleone, G

    2013-12-01

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

  16. 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.

  17. The corrected cast impression: an alternative technique.

    PubMed

    Walton, J N

    1993-11-01

    Although the corrected or altered cast impression technique is widely taught, it seems to be used very little, in part because it requires separate appointments for framework try-in, corrected cast impression, and occlusal registration. This article describes a technique whereby each of these procedures may be accomplished accurately in one appointment. Visible light-cured resin impression trays with integral occlusion rims are fabricated after the framework has been fitted. Standard procedures are used for the corrected cast impression, and interocclusal records are made with the framework with the impression attached. A stable occlusal registration material allows the interocclusal records to be set aside and used to articulate the corrected cast before the impression tray is separated from the cast. Benefits of this technique include significant time savings, improved accuracy, and simplified procedures. PMID:20830890

  18. 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 ? = 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 significant difference for each dimension measured (except for the inter-abutment distance between the first and the second die) between any two groups of stone models obtained from the four impression techniques. Pair wise comparison for each measurement did not reveal any significant difference (except for the faciolingual distance of the third die) between the casts produced using the two step double mix impression technique and the matrix impression system. The two step double mix impression technique produced stone dies that showed the least dimensional variation. During fabrication of a cast restoration, laboratory procedures should not only compensate for the cement thickness, but also for the increase or decrease in die dimensions. PMID:24431772

  19. Fundamental Aspects of Aminoalkyl Siloxane Softeners by Molecular Modeling and Experimental Methods

    Microsoft Academic Search

    MICHAEL W. SKINNER; Caibao Qian; STELIAN GRIGORAS; DANIEL J. HALLORAN; BRETT L. ZIMMERMAN

    1999-01-01

    The global textile industry has an ongoing need for improved softening products. Current materials systems, including those with siloxane polymers, exhibit certain limitations such as yellowing, high cost, and low softening efficiency. Investigations into fabric softening mechanisms invoke molecular modeling tools to simulate siloxane polymer and cotton fiber interactions at the molecular level. This research describes how certain polymer types

  20. Landfill siloxane gas sensing using differentiating, responsive phase coated microcantilever arrays.

    PubMed

    Long, Zhou; Storey, John; Lewis, Samuel; Sepaniak, Michael J

    2009-04-01

    Landfill biogases are being utilized more frequently as a new source of fuel energy. Volatile siloxane compounds usually contained in landfill biogases will form siloxane residues when the gases are burned, which significantly increases abrasion of combustion engines. Research on detection of siloxanes in landfill gas has been active during recent years with the principal analytical technique being gas chromatography/mass spectrometry (GC/MS). In our present work, we introduce a less expensive, compact methodology that employs microcantilever (MC) arrays for sensitive nanomechanical-based gas-phase sensing of the siloxanes. The cantilevers on the MC array were differentially coated on the active, nanostructured side with different responsive phases, and composite responses (magnitude of siloxane-induced MC bending) for four siloxanes were collected that exhibited selective signatures to aid in recognizing each siloxane. Limits of detection (LODs) derived from linear calibration plots were down to the sub-parts-per-million range, a sensitivity that is comparable with that of GC/MS reported by other researchers. Studies were performed in rather inert helium environment and a realistic matrix, and the overall response profiles and LODs were similar for both matrixes. A 5 week long-term reproducibility study illustrates the stability of the MC array. Moreover, the portable character of the MC array setup makes our method a very promising way to facilitate in-field detection of siloxanes in landfill gas in the future. PMID:19267478

  1. Siloxane-based hybrid semiconducting polymers prepared by fluoride-mediated suzuki polymerization.

    PubMed

    Lee, Junghoon; Han, A-Reum; Lee, Sang Myeon; Yoo, Dohyuk; Oh, Joon Hak; Yang, Changduk

    2015-04-01

    Siloxane-containing materials are a large and important class of organic-inorganic hybrids. In this report, a practical variation of the Suzuki polymerization to generate semiconducting polymeric hybrids based on siloxane units, which proceeds under essentially nonbasic conditions, is presented. This method generates solution-processable poly(diketopyrrolopyrrole-alt-benzothiadiazole) (PDPPBT-Si) consisting of the hybrid siloxane substituents, which could not be made using conventional methods. PDPPBT-Si exhibits excellent ambipolar transistor performance with well-balanced hole and electron FET mobilities. The siloxane-containing DPP-thiophene polymer classes (PDPP3T-Si and PDPP4T-Si), synthesized by this method, exhibit high hole mobility of up to 1.29?cm(2) ?V(-1) ?s(-1) . This synthetic approach should provide access to a variety of novel siloxane-containing conjugated semiconductor classes by using a variety of aryldihalides and aryldiboronic acids/esters. PMID:25677803

  2. Congenital Basilar Impression: Correlated Neurological Syndromes

    Microsoft Academic Search

    Pietro Bassi; Claudio Corona; Patrizia Contri; Andrea Paiocchi; Mario Loiero; Alfonso Mangoni

    1992-01-01

    A series of 8 cases operated on for symptomatic basilar impression associated with occipitalization of the atlas is reported (with or without atlantoaxial dislocation). Symptoms of onset (such as the frequent association between nuchal pain and vertigo) are emphasized and analyzed in relation to the pathogenetic mechanism that underlies the multiform symptomatology of the basilar impression. The diagnostic workup for

  3. Sport Fans' Impressions of Gay Male Athletes

    Microsoft Academic Search

    Jamonn Campbell; Denise Cothren; Ross Rogers; Lindsay Kistler; Anne Osowski; Nathan Greenauer; Christian End

    2011-01-01

    The purpose of this study was to examine sport fans' impressions of gay male athletes. Participants formed impressions of a fictional athlete from their favorite team after reading a short scenario about the player. The scenarios described the athlete as being gay or straight, and either becoming a distraction or not causing a distraction to the team. While males' ratings

  4. The neural dynamics of updating person impressions

    PubMed Central

    Cai, Yang; Todorov, Alexander

    2013-01-01

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

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

    PubMed

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

    2014-11-01

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

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

    SciTech Connect

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

    2013-10-15

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

  7. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification...provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures. (b)...

  8. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification...provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures. (b)...

  9. Going To Work: Make a Good Impression

    E-print Network

    Hoffman, Rosemarie

    2000-01-07

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

  10. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification...provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures. (b)...

  11. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification...provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures. (b)...

  12. 21 CFR 872.3660 - Impression material.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3660 Impression material. (a) Identification...provide models for study and for production of restorative prosthetic devices, such as gold inlays and dentures. (b)...

  13. Diffusion and Flow in Impression Creep Testing

    NASA Astrophysics Data System (ADS)

    Yang, Fuqian

    Some steady state vacancy diffusion problems caused by impression loading were analyzed. It was found that the impression velocity is proportional to the punching stress and the self-diffusivity of atoms for impression creep of a thin film by a flat end straight or cylindrical punch. For the same punching stress it is proportional to the thickness of the film and inversely to the square of the punch width or diameter for the film deposited on a rigid and impermeable substrate. Without the substrate, the impression velocity is inversely proportional to the thickness of the film but independent of the punch dimension. This analysis gives a simple way of detecting film decohesion from its substrate. For the situation of low Reynolds numbers, the viscous flow induced by a flat-end straight/cylindrical punch impressing into a half space was analyzed. It is shown that the impression velocity is proportional to the punching stress and the punch width/diameter, and inversely proportional to the viscosity. This result suggests a simple way of measuring the viscosity. Impression creep and stress relaxation experiments on a Sn-Pb eutectic alloy were carried out in the RSA II modified to use a 0.5 mm diameter cylindrical punch under 1.5 to 47 MPa punching stress and within a temperature range between 25^circC and 110^circC. Using the hyperbolic sine function between the impression velocity and the punching stress, a single activation energy, 55 kJ/mole was obtained. Based on the experimental data, a single mechanism of interfacial viscous shearing between the two eutectic phases is proposed for both creep and stress relaxation. The impression creep of a half-space with the Eyring hyperbolic sine constitutive equation was simulated by finite element analysis using the ABAQUS program. It turns out that the impression velocity is also a hyperbolic sine function of the punching stress. Application of this result to the Sn-Pb experiment shows that the elementary process of interface shearing also obeys the hyperbolic sine law.

  14. Polyvinyl alcohol battery separator containing inert filler

    Microsoft Academic Search

    D. W. Sheibley; L. C. Hsu; M. A. Manzo

    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

  15. 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.

  16. The Siloxane Bond and Its Influence on the Structure and Physical Properties of Organosilicon Compounds

    Microsoft Academic Search

    Mikhail G. Voronkov; Yu A. Yuzhelevskii; V. P. Mileshkevich

    1975-01-01

    The main characteristics of the structure of the siloxane bond are examined and the results of studies on the structures and properties of oxygen-containing silicon compounds by physical methods are reviewed. The bibliography includes 405 references.

  17. 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.

  18. Permeation of Substituted Silanes and Siloxanes Through Selected Gloves and Protective Clothing

    Microsoft Academic Search

    Gary O. Nelson; Stephen J. Priante; Michael Strong; Dennis Anderson; Jeanne Fallon-Carine

    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;

  19. 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

  20. 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.

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

    PubMed

    Tran, Tri Manh; Kannan, Kurunthachalam

    2015-04-01

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

  2. Are First Impressions Important in Academia?

    Microsoft Academic Search

    Aloysius Siow

    1991-01-01

    This paper demonstrates that the popular belief that first impressions are important in determining career success is theoretically sound. The model is then tested with salary data on mathematicians and economists. In general, the point estimates show that the long run increase in salary from an additional article or citation declines with the age at which it is received. The

  3. Cytotoxicity and membrane damage in vitro by inclusion complexes between gamma-cyclodextrin and siloxanes.

    PubMed

    Felix, K; Janz, S; Pitha, J; Williams, J A; Mushinski, E B; Bornkamm, G W; Potter, M

    1996-01-01

    Inclusion complexes of gamma-cyclodextrin and octamethylcyclotetrasiloxane (D4), decamethyltetrasiloxane (M10TS), and 1,3,5,7-tetramethyltetravinylcyclotetra - siloxane (TMTV-D4) were prepared to compare the cytotoxic effects of siloxanes in vitro. In these preparations, the hydrophobic siloxanes are surrounded by a hydrophilic shell of eight circularly linked D-glucose molecules (gamma-cyclodextrin), and upon contact with plasma membranes the siloxane molecule can intercalate into the lipid bilayer of the cell membrane. XRPC24, 2-11 plasmacytoma, CH12.LX lymphoma and P388D1 macrophage-like cells were used as indicator cells in toxicity assays. Using an MTT tetrazolium reduction to formazan test, a colorimetric method to determine the number of viable cells, the 50% minimal lethal doses (CD50) for the siloxane compounds were found to range from 30 to 50 microM. Sublethal doses (e.g., 15 microM and lower) resulted in the loss of lactate dehydrogenase (LDH) and glutathione (GSH) from the cytosolic compartment of the target cells and thus indicated cytotoxicity. Treatment of macrophages with siloxanes resulted in a higher production of interleukin-6 (IL-6) than was exhibited by untreated macrophages. The B9 cell bioassay of these treated cells showed as much as a 10 fold higher production (500 U/ml) of IL-6 than did the untreated cells. The degree of increase was dependent on the compound and concentration used. The results of this study show that low molecular weight siloxanes produce lethal effects on B-lymphocyte derived target cells in vitro and permeabilize the plasma membranes at lower sublethal concentrations. PMID:8565593

  4. Distribution, source, fate and bioaccumulation of methyl siloxanes in marine environment.

    PubMed

    Hong, Wen-Jun; Jia, Hongliang; Liu, Cheng; Zhang, Zifeng; Sun, Yeqing; Li, Yi-Fan

    2014-08-01

    Studies have shown that some cyclic methyl siloxanes were identified as characterized of persistent, bioaccumulated, toxic, and potential to ecological harm. In this study, we determined methyl siloxanes in seawater, sediment and bottom fish samples collected from marine environment in Northeast China. The mean concentrations of total methyl siloxanes were 46.1 ± 27.2 ng/L, 12.4 ± 5.39 ng/g dry weight (dw) and 5.10 ± 1.34 wet weight (ww) in seawater, sediment and fish, respectively. Very strong and significant correlations (r = 0.94, p < 0.0001) were found in compositions of methyl siloxanes between seawater and sewage, indicating that sewage was the main source of methyl siloxanes in the marine area studied. It was found that the mean value of biota-sediment accumulation factor (BSAF) was.0.716 ± 0.456 for D4, 0.103 ± 0.0771 for D5, 1.06 ± 0.528 for D6 and 0.877 ± 0.530 for D7. PMID:24852408

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

    PubMed

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

    2013-10-01

    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. PMID:23684695

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

    SciTech Connect

    Suzuki, Kazumasa [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); International Laboratory of Materials Science and Nanotechnology (iLMNT), Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Laboratorio di Scienz (Italy); Tokudome, Yasuaki, E-mail: masa@photomater.com; Takahashi, Masahide, E-mail: masa@photomater.com [Department of Materials Science, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); International Laboratory of Materials Science and Nanotechnology (iLMNT), Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2014-10-21

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

  7. ANIMAL ANALOGIES IN FIRST IMPRESSIONS OF FACES.

    PubMed

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

    2011-08-01

    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

  8. Leaf Impressions: A Model for Carbonization

    NSDL National Science Digital Library

    Stephen Greb

    In this activity students make leaf impressions on paper to illustrate how carbonization works. They use the leaf press method to demonstrate staining as a model for carbonization, when living tissue leaves a carbon film in sediment and rock. The students will discover that many plant fossils are preserved through carbonization and that soft parts of animals including skin and fur have also been preserved as fossils through the process of carbonization.

  9. [Substantiation of medical-engineering specifications for polymethyl siloxane removal by life support systems].

    PubMed

    Pakhomova, A A; Aksel'-Rubinshte?n, V Z; Mikos, K N; Nikitin, E I

    2009-01-01

    Analysis of experimental data about the quantitative and qualitative chemical make-up of air in the orbital station Mir and International space station (ISS) showed a permanent presence of silicon. The main source of silicon contaminants seems to be a variety of polymethyl siloxane liquids and siloxane coating of electronics. The article describes the volatile silicon contaminants detected in space stations air. To control concentrations of silicon, the existing air purification system needs to be augmented with carbons having the micropore entrance larger than diameters of silicon-containing molecules. It is also important to elaborate the technology of polymethyl siloxane liquids synthesis so as to reduce the amount of volatile admixtures emission and to observe rigorously the pre-flight off-gassing requirements with special concern about silicon coatings. PMID:19621808

  10. 21 CFR 872.6880 - Preformed impression tray.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  11. 21 CFR 872.6880 - Preformed impression tray.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  12. 21 CFR 872.6880 - Preformed impression tray.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  13. 21 CFR 872.6880 - Preformed impression tray.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...impression material, such as alginate, to make an impression of a patient's teeth or alveolar process (bony tooth sockets) to reproduce the structure of a patient's teeth and gums. (b) Classification. Class I (general...

  14. Molecular toughening of epoxy resins through siloxane modification

    NASA Astrophysics Data System (ADS)

    Zhang, Man

    2005-11-01

    The fracture resistance of epoxy resins is significantly improved through a new molecular toughening mechanism without sacrificing the desired thermal and mechanical properties. A liquid diglycidyl ether of bisphenol-A type epoxy resin (DGEBA) was modified using a methylphenyl siloxane (MPS) oligomer under the catalysis of tetraisopropyl titanate (TPT). A variety of characterization techniques confirmed that the methoxyl end group of the MPS modifier was reacted with the hydroxyl group of the DGEBA resin forming a grafted molecular structure. The curing kinetics between DGEBA and an aromatic amine, metaphenylenediamine (mPDA), was extensively investigated using isothermal and dynamic differential scanning calorimetry (DSC) techniques. The MPS modified DGEBA/mPDA systems follow the same autocatalytic curing mechanism as the unmodified one. Based on a time-temperature-transformation (TTT) diagram, the optimum curing conditions were determined as 130°C for 2 hours curing and 170°C for 3 hours postcuring. The DiBenedetto and Wisanrakkit/Gillham models provide a satisfactory prediction of the Tg-alpha relationship over the whole conversion range. Both the critical stress intensity factor (KIc) and the critical strain energy release rate (GIc) of the modified DGEBA/mPDA samples increase with an increasing MPS content. At 15 wt% MPS content, KIc shows a 2.5-fold increase, and GIc shows a 8.8-fold increase, compared with the unmodified DGEBA/mPDA system. For the MPS modified DGEBA/mPDA systems, the high glass transition temperature and the thermal stability were well maintained. The tensile and the flexural strengths and strains were improved while the Young's modulus and the flexural modulus were slightly decreased. The moisture resistance was improved. The morphologies of the unmodified and the MPS modified DGEBA/mPDA systems were studied using both optical and scanning electron microscopy techniques. With the incorporation of the MPS oligomer, a two-phase microstructure was observed on the fracture surface. The second phase particle may be caused by the MPS oligomer coalescing during curing. The toughening mechanisms identified include localized shear deformation of the epoxy matrix, particle tearing, fracture and cativation, and crack deflection. The factors including modification method, MPS modifier type, and curing agent type affect the structure-property relationship of modified epoxy resin. The chemical modification method is more efficient in enhancing the fracture toughness of DGEBA/mPDA system than the physical blending method. The differences in the fracture toughness of various types of siloxane-modifier DGEBA systems can be attributed to their different morphological structures. The MPS modifier is more efficient in improving the fracture toughness of aromatic amine, mPDA, cured DGEBA system than that of aliphatic amine, polyoxypropylene diamine (POPDA), cured DGEBA system.

  15. 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, ?2?(rc), and the values of ?(rc) and G(rc)/?(rc), the Si-O bond qualifies as an intermediate bonded interaction. For bonded interactions of intermediate character, ?2?(rc) increases linearly as ?(rc) increases, the greater the shared character, the larger the value of ?2?(rc). In addition, a mapping of ?2?(r) serves to highlight those Lewis base domains that are susceptible to electrophilic attack by H like the O atom in coesite involved in bent Si-O-Si angles, the narrower the angle, the greater the affinity for H . On the basis of the net charges conferred on the Si and O atoms and the bonded radii of the two atoms, the Si-O bond of stishovite with six-coordinated Si and three-coordinated O is indicated to be more ionic in character than that in quartz with four-coordinated Si and two coordinated O. Unlike the conclusion reached for ionic and crystal radii (quantum mechanical unobservables), it is the bonded radius of the O atom that increases with the increasing coordination number of Si, not the radius of the Si atom. The modeling of the electron density distributions for quartz, coesite and beryl as a function of pressure indicates that the shared character of the bonded interactions in these minerals increases slightly with increasing pressure. The insight provided by the calculations and the modeling of the electron density distributions and the structures of the silica polymorphs bodes well for future Earth materials studies that are expected to improve and clarify our understanding of the connection between properties and structure within the framework of quantum mechanical observables, to find new and improved uses and to predict new properties for materials and to enhance our understanding of crystal chemistry and chemical reactions of materials in their natural environment at the atomic level

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

    PubMed

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

    2014-04-01

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

  17. Covalent immobilisation of protease and laccase substrates onto siloxanes.

    PubMed

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

    2010-08-01

    Immobilisation of enzyme substrates is a powerful tool in the detection of enzymes in the chemosphere and the environment. A siloxane based strategy for the covalent immobilisation of oxidoreductase and protease substrates was developed involving activation of silica gel and polyethylene terephthalate (PET) as model carriers with (3-aminopropyl)-triethoxysilane or (3-mercaptopropyl)-trimethoxysilane (APTS, MPTS). Ferulic acid and L-Leucine-p-nitroanilide, Gly-Phe p-nitroanilide (GPpNA) and N-Succinyl-Ala-Ala-Pro-Leu p-nitroanilide (SAAPLpNA) as laccase and protein substrates, respectively, were covalently attached using glutaraldehyde or carbodiimide based cross-linking strategies. In contrast to conversion in solution, immobilised SAAPLpNA was hydrolysed much faster by protease than immobilised GPpNA indicating steric hindrance with decreasing chain length between point of attachment and site of enzyme attack. Immobilised ferulic acid was oxidised by laccase both in case of MPTS and APTS-modified silica gel giving clearly visible colour changes with Delta E values of 7.2 and 2.3, respectively after 24h of incubation, where Delta E describes the distance between two colours. Similarly, clearly visible colour changes with a Delta E value of 8.6 were seen after laccase treatment of ferulic acid immobilised on APTS activated PET as carrier. Limited surface hydrolysis of PET with a cutinase enhanced coupling of APTS and ferulic acid due to a larger number of hydroxyl groups available on the surface and consequently led to a higher colour difference of Delta E=12.2 after laccase oxidation. The covalent coupling product between ferulic acid and 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane was identified by LC-MS (M+1m/z601) and successfully oxidised with laccase. PMID:20547407

  18. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  19. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  20. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  1. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  2. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  3. Multiband Impressions of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Marscher, Alan P.

    I summarize the activity of the workshop ``Multiband Approach to AGN'' held in Bonn, Germany from 30 September to 2 October 2004. I compare the state of knowledge of the field to what existed in the 1960s to demonstrate that we have indeed made progress. I highlight some impressive advances of our knowledge that I gleaned from the presentations at the workshop. I also list some embarrassing scandals where gaps in understanding still exist despite our often heroic attempts to describe accurately the physics of AGNs.

  4. Polyvinyl alcohol battery separator containing inert filler

    NASA Astrophysics Data System (ADS)

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

    1981-06-01

    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.

  5. Polyvinyl alcohol battery separator containing inert filler

    SciTech Connect

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

    1981-06-01

    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 enhences 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.

  6. Polymer-Supported Siloxane Transfer Agents for Pd-Catalyzed Cross-Coupling Reactions

    PubMed Central

    Nguyen, Minh H.; Smith, Amos B.

    2013-01-01

    The design, synthesis and validation of a ROMP polymer supporting siloxane transfer agents have been achieved that permit efficient palladium-catalyzed cross-coupling reactions. The solubility properties of the polymer not only facilitate product purification, but also recycling without significant loss of cross-coupling activity. PMID:23901881

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

    PubMed

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

    2013-08-01

    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

  8. Adsorptive characteristics of the siloxane surfaces of reduced-charge bentonites saturated with tetramethylammonium cation.

    PubMed

    Ruan, Xiuxiu; Zhu, Lizhong; Chen, Baoliang

    2008-11-01

    To elucidate interactions of neutral organic contaminants (NOCs) with siloxane surfaces (often referred to hydrophobic nanosites)found between cations in 2:1 phyllosilicates, adsorption of aliphatic and aromatic compounds onto both internal and external siloxane surfaces oftetramethylammonium-intercalated bentonite with a cation exchange capacity (CEC) of 108 cmol/kg (108TMA) and its reduced-charge bentonite (CEC = 65 cmol/ kg, 65TMA) were investigated. Reduction of the layer charge and saturation of bentonite interlayers with TMA+ modify the interlayer microenvironments, which dramatically promote adsorption of NOCs. Specific mechanisms (i.e., steric restriction and phenyl-effect) control the adsorption of NOCs onto internal siloxane surfaces of TMA+ -bentonites from water. The adsorption sites of 108TMA can not provide sufficient space to accommodate NOCs, hence hindering adsorption. Adsorption mechanism on 65TMA varies with solute-loadings, from polarity-selective at low loadings to aromaticity-preferable at high loadings. Significant contribution of phenyl-effect between adsorbed-solutes to aromatics adsorption on 65TMA is found. Solvent polarity effect on the aggregation of TMA+ -bentonites and aniline adsorption demonstrated that the contribution of external siloxane surfaces to favor adsorption in n-hexane are actually exploited but generally omitted. These observations provide significant insights into distinguishing different uptake mechanisms as well as the potential means for the rational design of better organic sorbents. PMID:19031880

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

    Microsoft Academic Search

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

    2010-01-01

    Landfill or digester gas can contain man-made volatile methylsiloxanes (VMS), usually in the range of a few milligrams per normal cubic metre (Nm3). Until now, no standard method for siloxane quantification exists and there is controversy with respect to which sampling procedure is most suitable. This paper presents an analytical and a sampling procedure for the quantification of common VMS

  10. 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 ?g/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

  11. 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

  12. 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....

  13. 75 FR 61175 - Polyvinyl Alcohol From Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ...INTERNATIONAL TRADE COMMISSION [Investigation No. 731-TA-1088 (Final)] Polyvinyl Alcohol...phase of antidumping investigation No. 731-TA-1088 (Final) under section 735...solution color 20mm cell, 10.0 maximum APHA units, haze index, 20mm cell, 5.0,...

  14. MECHANISM OF DISCOLORATION OF IRRADIATED POLYVINYL CHLORIDE

    Microsoft Academic Search

    Shun-Ichi Ohnishi; Yoshiharu Nakajima; Isamu Nitta

    1962-01-01

    The radiation chemical process in polyvinyl chloride was studied by ; means of electron spin resonance, optical spectroscopy, and measurement of gas ; evolution. The chief technique was to irradiate sampies at - 196 deg C and then ; follow the change or changes with rising temperature. primary radicals, such as --; CHâ--CH--CHâ-- and -- CHCl -- CH-- CHCl--, were

  15. Some reactions of dehydrochlorinated polyvinyl chloride

    Microsoft Academic Search

    É. P. Oleinik; N. S. Vasileiskaya; G. A. Razuvaev

    1968-01-01

    1.Dehydrochlorinated polyvinyl chloride (PVC) is a black polymer, containing a system of conjugated double bonds and possessing unpaired electrons; it adds HCl. In this case, the system of conjugation is disrupted, but the EPR signal is retained.2.In the presence of oxygen, the amount of HCl added to the black polymer is substantially increased (by four to fivefold). The product obtained

  16. Polyvinyl alcohol: A taste sensing material

    Microsoft Academic Search

    Sarmishtha Majumdar; Basudam Adhikari

    2006-01-01

    There are reports of taste sensor fabrication by incorporating lipids in a PVC matrix. We have taken an attempt to prepare a taste sensor material by using a functionalized polymer. Polyvinyl alcohol (PVA) has been modified to fabricate the sensor material. The research work covers polymer membrane preparation, morphology study, structural characterization of the membrane, and study of the taste

  17. Pyrolytic carbon membranes containing silica derived from poly(imide siloxane): the effect of siloxane chain length on gas transport behavior and a study on the separation of mixed gases

    Microsoft Academic Search

    Ho Bum Park; Chul Ho Jung; Youn Kook Kim; Sang Yong Nam; Sun Yong Lee; Young Moo Lee

    2004-01-01

    Poly(imide siloxane) (PIS) precursors have been synthesized in different compositions and appraised in their ability to form carbon membranes containing silica (C–SiO2). During inert pyrolysis, the imide domains in the PIS were transformed into a carbon-rich phase conferring a molecular sieving capability for molecular pairs of small gases, such as H2\\/N2, He\\/N2, CO2\\/N2, and O2\\/N2. The siloxane domains in the

  18. 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

  19. Elastomeric impression materials: effect of bulk on accuracy.

    PubMed

    Eames, W B; Sieweke, J C; Wallace, S W; Rogers, L B

    1979-03-01

    Impression trays were fabricated providing 2, 4, and 6 mm spaces to determine the stability and accuracy of nine elastomeric impression materials on a simulated full crown preparation steel die. The interface space of 2 mm produced the most accurate impressions for all of the materials tested. All impression materials except one fell within the revised American Dental Association Specifications. The clinical-type tests, using castings on dies poured from these materials, corroborated the acceptance of those materials and techniques exhibiting the least dimensional change. PMID:283231

  20. The fungicidal effect of ultraviolet light on impression materials

    SciTech Connect

    Ishida, H.; Nahara, Y.; Tamamoto, M.; Hamada, T. (Department of Prosthetic Dentistry, Hiroshima University, School of Dentistry (Japan))

    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.

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

    PubMed

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

    2015-01-01

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

  2. 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

  3. Polyvinyl alcohol membranes as alkaline battery separators

    Microsoft Academic Search

    D. W. Sheibley; O. Gonzalez-Sanabria; M. Manzo

    1982-01-01

    Polyvinyl alcohol (PVA) cross-linked with aldehyde reagents yields membranes that demonstrate properties that make them suitable for use as alkaline battery separators. Film properties can be controlled by the choice of cross-linker, cross-link density and the method of cross-linking. Three methods of cross-linking and their effects on film properties are discussed. Film properties can also be modified by using a

  4. 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.

  5. Microstructural Organization of Elastomeric Polyurethanes with Siloxane-Containing Soft Segments

    NASA Astrophysics Data System (ADS)

    Choi, Taeyi; Weklser, Jadwiga; Padsalgikar, Ajay; Runt, James

    2011-03-01

    In the present study, we investigate the microstructure of two series of segmented polyurethanes (PUs) containing siloxane-based soft segments and the same hard segments, the latter synthesized from diphenylmethane diisocyanate and butanediol. The first series is synthesized using a hydroxy-terminated polydimethylsiloxane macrodiol and varying hard segment contents. The second series are derived from an oligomeric diol containing both siloxane and aliphatic carbonate species. Hard domain morphologies were characterized using tapping mode atomic force microscopy and quantitative analysis of hard/soft segment demixing was conducted using small-angle X-ray scattering. The phase transitions of all materials were investigated using DSC and dynamic mechanical analysis, and hydrogen bonding by FTIR spectroscopy.

  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. PPA Department Heads Initial Impressions and SLAC Challenges

    E-print Network

    Wechsler, Risa H.

    1 PPA Department Heads Initial Impressions and SLAC Challenges James Tarpinian ES&H Director for 2012 ES&H Director Chief Safety Officer #12;3 Initial impressions Evolutionary change to safety: Lab Director and ALDs model behavior ·Resources are adequate to do what is planned ·Great staff

  8. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...form a custom impression tray for use in cases in which a preformed impression tray is not suitable, such as the fabrication of crowns, bridges, or full dentures. A preliminary plaster or stone model of the patient's teeth and gums is made. The...

  9. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...form a custom impression tray for use in cases in which a preformed impression tray is not suitable, such as the fabrication of crowns, bridges, or full dentures. A preliminary plaster or stone model of the patient's teeth and gums is made. The...

  10. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...form a custom impression tray for use in cases in which a preformed impression tray is not suitable, such as the fabrication of crowns, bridges, or full dentures. A preliminary plaster or stone model of the patient's teeth and gums is made. The...

  11. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...form a custom impression tray for use in cases in which a preformed impression tray is not suitable, such as the fabrication of crowns, bridges, or full dentures. A preliminary plaster or stone model of the patient's teeth and gums is made. The...

  12. 21 CFR 872.3670 - Resin impression tray material.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...form a custom impression tray for use in cases in which a preformed impression tray is not suitable, such as the fabrication of crowns, bridges, or full dentures. A preliminary plaster or stone model of the patient's teeth and gums is made. The...

  13. A 3D Impression Acquisition System for Forensic Applications

    E-print Network

    Tuceryan, Mihran

    A 3D Impression Acquisition System for Forensic Applications Ruwan Egoda Gamage, Abhishek Joshi a method with which 3D images of tire track and footprint impressions at crime scenes can be captured. The same technique can also be used in the laboratory to create 3D depth images of suspect tires or shoe

  14. Motion cues that make an impression?

    PubMed Central

    Koppensteiner, Markus

    2013-01-01

    The current study presents a methodology to analyze first impressions on the basis of minimal motion information. In order to test the applicability of the approach brief silent video clips of 40 speakers were presented to independent observers (i.e., did not know speakers) who rated them on measures of the Big Five personality traits. The body movements of the speakers were then captured by placing landmarks on the speakers' forehead, one shoulder and the hands. Analysis revealed that observers ascribe extraversion to variations in the speakers' overall activity, emotional stability to the movements' relative velocity, and variation in motion direction to openness. Although ratings of openness and conscientiousness were related to biographical data of the speakers (i.e., measures of career progress), measures of body motion failed to provide similar results. In conclusion, analysis of motion behavior might be done on the basis of a small set of landmarks that seem to capture important parts of relevant nonverbal information. PMID:24223432

  15. High Temperature Membrane Based on Poly(dimethyl siloxane) and Porous Poly(tetrafluoroethylene) Film

    Microsoft Academic Search

    Lee-Jin Ghil; Hee-Woo Rhee

    2009-01-01

    Sulfonic acid-based membrane gives the relatively high conductivity only in the presence of water, but phosphoric acid-based membrane presents the relatively high proton conductivity without water because of its self-dissociation natures to develop high temperature PEMFCs. We synthesized the membrane that has phosphorous groups based on poly(dimethyl siloxane) (PDMS). PDMS, which is intrinsically hydrophobic, was modified to be amphiphilic by

  16. Preparation of poly(lactic acid)\\/siloxane\\/calcium carbonate composite membranes with antibacterial activity

    Microsoft Academic Search

    Shingo Tokuda; Akiko Obata; Toshihiro Kasuga

    2009-01-01

    A poly(lactic acid) (PLA)\\/siloxane\\/calcium carbonate composite membrane containing mercapto groups (PSC-SH) with antibacterial ability and excellent bone-forming ability was prepared using 3-mercaptopropyltrimethoxysilane for application in guided bone regeneration. Mercapto groups were reported to adsorb silver ions, which are well known to show antibacterial activity. Ionic silicon species were reported to stimulate the proliferation of osteoblasts. A PSC-SH membrane with a

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

    Microsoft Academic Search

    1996-01-01

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

  18. Personality impressions associated with four distinct humor styles.

    PubMed

    Kuiper, Nicholas A; Leite, Catherine

    2010-04-01

    This study examined how personality impressions about another person are influenced by the style of humor that person displays. Four distinct styles were examined, with two of these being adaptive (affiliative and self-enhancing humor), and two being maladaptive (aggressive and self-defeating humor). Participants read descriptions of an individual displaying each humor style, and then rated that individual on several other personality attributes (e.g., friendly, complaining). The adaptive humor styles enhanced personality impressions of another individual, whereas the maladaptive styles had strong detrimental effects. Furthermore, participants provided clearly differentiated personality impressions within both the adaptive and maladaptive humor categories. Affiliative humor led to more positive impressions of another than self-enhancing humor; whereas aggressive humor resulted in more negative personality impressions than self-defeating humor. These findings were discussed in terms of approaches to humor that acknowledge the multifaceted nature of this construct and the resulting impact on social relationships. PMID:19674401

  19. Critical Finding Capture in the Impression Section of Radiology Reports

    PubMed Central

    Gershanik, Esteban F.; Lacson, Ronilda; Khorasani, Ramin

    2011-01-01

    Introduction Radiology reports communicate imaging findings to ordering physicians. The substantial information in these reports often causes physicians to focus on the summarized “impression” section. This study evaluated how often a critical finding is documented in the report’s “impression” section and describes how an automated application can improve documentation. Methods A retrospective review of all chest CT scan reports finalized between October, 2009 and September, 2010 at an academic institution was performed. A natural language processing application was utilized to evaluate the frequency of reporting a pulmonary nodule in the “impression” section, versus the “findings” section of a report. Results Results showed 3,401 reports with documented pulmonary nodules in the “findings” section, compared to 2,162 in the “impression” section – a 36.4% difference. Conclusion The study revealed significant discrepant documentation in the “findings” versus “impression” sections. Automated systems could improve such critical findings documentation and communication between ordering physicians and radiologists. PMID:22195100

  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. 78 FR 20890 - Polyvinyl Alcohol From Taiwan: Preliminary Results of Antidumping Duty Administrative Review...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-08

    ...Administration [A-583-841] Polyvinyl Alcohol From Taiwan: Preliminary Results of Antidumping...the antidumping duty order on polyvinyl alcohol (PVA) from Taiwan. The period of review...Duty Administrative Review: Polyvinyl Alcohol from Taiwan; 2010-2012'' dated...

  2. 78 FR 39256 - Polyvinyl Alcohol From Taiwan: Rescission of Antidumping Duty Administrative Review; 2012-2013

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

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

  3. The Irresistible Costs of Impressing Others Managing Impressions and Regulating Behavior

    NSDL National Science Digital Library

    Jamie G. McMinn

    2007-01-01

    Recent research indicates that people who boast to friends and those who are modest to strangers are less able to regulate their behaviors on other tasks. This case study presents a scenario in which four college roommates use different strategies to manage the impressions they make at a party. When they are later presented with a tray of tempting cookies, students are asked to predict how many each will eat and to justify their answers using the research results. Designed for use in a social psychology course, the case is also appropriate for introductory, health, and motivation psychology courses.

  4. 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

  5. Continuous microcellular foaming of polyvinyl chloride and compatibilization of polyvinyl chloride and polylactide composites

    Microsoft Academic Search

    Bhavesh Shah

    2007-01-01

    This dissertation focuses on overcoming existing limitations of WPCs which prevent them from realizing their full market potential. These limitations include: (i) lack of a continuous extrusion process for microcellular foaming of polyvinyl chloride (PVC) and its composites using supercritical fluids to reduce the high density of the WPCs, (ii) need for an efficient coupling agent for WPCs to overcome

  6. Preparation of synthetic carbon adsorbents by polyvinyl chloride (PVC) carbonization

    Microsoft Academic Search

    SECTIO AA; M. Seredych; A. Gierak

    Preparation of synthetic carbon adsorbents by carbonization of polyvinyl chloride (produced by Anwil, Wocawek, Poland) is described in the paper. The influence of polyvinyl chloride (PVC) carbonization conditions on the porous structure of the obtained carbon was studied. Part of the prepared carbonizates was activated in the atmosphere of in water vapour and carbon dioxide (600 - 800 oC). The

  7. Flow-Injection Determination of Elemental Iodine by Polyvinyl Alcohol

    Microsoft Academic Search

    V. V. Kuznetsov; Yu. V. Ermolenko; L. Seffar

    2004-01-01

    Complex formation between elemental iodine and polyvinyl alcohol was studied under flow conditions. The formation of substances with a weak hyperchromic effect in the UV and visible regions was detected. It was shown that this reaction could be used under flow conditions provided the gel-forming ability and viscosity of the polyvinyl alcohol solution were reduced by adding isopropanol and 6%

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

    NASA Astrophysics Data System (ADS)

    Prosanov, I. Yu.

    2013-02-01

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

  9. Effects of Gamma Rays on Aqueous Solution of Polyvinyl Alcohol

    Microsoft Academic Search

    Osamu Saito

    1959-01-01

    The general treatment developed in previous papers is applied to the case where the aqueous solution of polyvinyl alcohol is irradiated by gamma rays and the results are compared with Danno's measurements. The behaviours of irradiated aqueous solution of polyvinyl alcohol before and after gelation are well explained by the author's general theory. It is concluded from the analysis that

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

    E-print Network

    Guo, John Zhanhu

    RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol: interfacial layer and bulk:1 and 14 nm for 50:1). The presence of polyvinyl alcohol (PVA) limits the particle growth (15 nm for 20 to the nanoparticle surface, the nanoparticles are found not only to increase the PVA cross-linking with an increase

  11. 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

  12. Impression management and food intake. Current directions in research.

    PubMed

    Vartanian, Lenny R

    2015-03-01

    This paper reviews recent research on consumption stereotypes (judgments of others based on what they eat) and impression management (modifying one's eating behavior in order to create a particular impression). A major recent focus in the literature has been on masculinity and meat eating, with research showing that meat is strongly associated with masculinity, and that individuals who follow a meat-based diet are perceived as more masculine than are individuals who follow a vegetarian diet. Although direct evidence for impression management through food intake remains sparse, a number of methodological approaches (including priming techniques and ecological valid assessments) are described that could be used in future research to identify the motives underlying people's eating behavior. Consumption stereotypes and impression management may be important influences on people's eating behavior, but the complexities of how, when, and for whom these factors influence food intake are still not well understood. PMID:25149198

  13. Coping with stereotype threat: Denial as an impression management strategy

    E-print Network

    Von Hippel, W.; Von Hippel, C.; Conway, Leanne; Preacher, K. J.; Schooler, J. W.; Radvansky, G. A.

    2005-01-01

    Four experiments tested the hypothesis that people who are concerned with impression management cope with stereotype threat through denial. Consistent with this hypothesis, temporary employees threatened by a stereotype of incompetence (Study 1...

  14. 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 ...

  15. Siloxane-based thin films for corrosion protection of stainless steel in chloride media

    Microsoft Academic Search

    Sérgio Meth; Natali Savchenko; Federico A. Viva; David Starosvetsky; Alec Groysman; Chaim N. Sukenik

    2011-01-01

    The corrosion protection of stainless steel (SS 316L) provided by layers of SiO2 and by siloxane-anchored self-assembled monolayer (SAMs) was assessed by cyclic voltammetry (CV) and by potentiostatic current\\u000a transient in sodium chloride media. The SAMs were composed of octadecyltrimethoxysilane anchored onto a thin (1–2 nm) layer\\u000a of SiO2. The initial SiO2 layer was obtained by treatment with tetraethoxyorthosilicate. Successive layers

  16. 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.

  17. 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.

  18. Fabrication of long poly(dimethyl siloxane) nanochannels by replicating protein deposit from confined solution evaporation

    PubMed Central

    Lo, Kuo-Feng; Juang, Yi-Je

    2012-01-01

    A relatively simple, inexpensive and reliable technique was developed to fabricate an array of nanochannels. Moreover, the nanochannels are directly integrated to microchannels as a whole, which facilitates solution loading from the millimeter-scaled loading reservoirs into the nanochannels. It is found that continuous bovine serum albumin (BSA) line structures with triangle-like cross section at nanoscale can be obtained by evaporation of BSA solution with concentration between 0.5?wt.?% and 1?wt.?% inside the microchannels. The poly(dimethyl siloxane) nanochannels were replicated from these line structures, followed by sealing with the glass slide. The DNA molecules can be stretched inside the nanochannels as fabricated. PMID:23781292

  19. 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

  20. Microsphere-integrated gelatin-siloxane hybrid scaffolds for bone tissue engineering: in vitro bioactivity & antibacterial activity

    Microsoft Academic Search

    Lin Wang; Bing Yu; Li-ping Sun; Lei Ren; Qi-qing Zhang

    2008-01-01

    Microsphere integrated gelatin-siloxane hybrid scaffolds were successfully synthesized by using a combined sol-gel processing,\\u000a post-gelation soaking and freeze-drying process. A bone-like apatite layer was able to form in the Ca2+-containing porous hybrids upon soaking in a simulated body fluid (SBF) up to 1 day. The rate of gentamicin sulfate (GS) release\\u000a from the GS-loaded gelatin-siloxane hybrid microsphere became constant after

  1. 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

  2. Polyvinyl alcohol membranes as alkaline battery separators

    SciTech Connect

    Sheibley, D.W.; Gonzalez-Sanabria, O.; Manzo, M.

    1982-01-01

    Polyvinyl alcohol (PVA) cross-linked with aldehyde reagents yields membranes that demonstrate properties that make them suitable for use as alkaline battery separators. Film properties can be controlled by the choice of cross-linker, cross-link density and the method of cross-linking. Three methods of cross-linking and their effects on film properties are discussed. Film properties can also be modified by using a copolymer of vinyl alcohol and acrylic acid as the base for the separator and cross-linking it similarly to the PVA. Fillers can be incorporated into the films to further modify film properties. Results of separator screening tests and cell tests for several variations of PBA films are discussed.

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

    PubMed Central

    Cole, Megan A.; Bowman, Christopher N.

    2012-01-01

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

  4. Hybrid scaffolds of gelatin-siloxane releasing stromal derived factor-1 effective for cell recruitment.

    PubMed

    Dashnyam, Khandmaa; Perez, Roman; Lee, Eun-Jung; Yun, Ye-Rang; Jang, Jun-Hyeog; Wall, Ivan B; Kim, Hae-Won

    2014-06-01

    Scaffolds with the capacity to deliver signaling molecules are attractive for bone regeneration. Here, we developed bioactive siloxane-gelatin hybrid scaffolds via a sol gel process containing stromal derived factor-1 (SDF-1) to recruit osteoprogenitor/stem cells. The process was undertaken under room temperature aqueous conditions, which enabled therapeutic molecules to be effectively incorporated. After the sol-gel reaction and lyophilization process, well-crosslinked hybrid scaffolds were obtained with porosities of 80-90%. Dynamic mechanical analysis of the hybrid scaffolds showed significant improvement in storage modulus values (from 10 to 110 kPa) with increasing siloxane content. The protein release capacity of the scaffolds was investigated using a model protein cytochrome C (cyto C). The cyto C safely loaded onto the scaffolds exhibited, except the initial burst of 30% within a day, highly sustainable release, with approximately 70-80% of the loading amount for up to 4 weeks. Target molecule SDF-1 was loaded and released from the scaffolds, and the effects on the homing of mesenchymal stem cell were studied. Results demonstrated significant enhancement in the migration of cells to the SDF-1 loaded scaffolds. Taken together, the developed hybrid scaffolds are considered to be useful in loading and delivering signaling molecules such as SDF-1 to recruit osteoprogenitor /mesenchymal stem cells in the bone regeneration process. PMID:23776167

  5. Formation mechanism and anticorrosive properties of thin siloxane films on metal surfaces

    SciTech Connect

    Petrunin, M.A.; Nazarov, A.P.; Mikhailovski, Yu.N. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Physical Chemistry

    1996-01-01

    The adsorption of different ethoxysilanes on Al was studied. It was established that during polymolecular adsorption of ethoxysilanes from the vapor phase on aluminum the first monolayer is adsorbed irreversibly with adsorption van der Waals bonds between silane molecules and the aluminum surface. The covalent bonding of silanes with the surface (Al-O-Si bonds) occurs in the presence of adsorbed water on the aluminum surface. The presence of a silane monolayer on Al decreases water adsorption on the surface, and inhibits hydration of the oxide metal film. The formation of a negatively charged siloxane film on the aluminum surface inhibits local metal corrosion, and a positively charged layer activates it in chloride containing media. The formation of the surface siloxane polymer by the modification of metals inhibits the metal dissolution under polymer coatings. It is caused by silane chemisorption and negative charging of the metal surface. The presence of negatively charged groups causes difficulties of an electrostatic character for the migration of aggressive ions to the metal surface.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  7. Effect of Time on Gypsum-Impression Material Compatibility

    NASA Astrophysics Data System (ADS)

    Won, John Boram

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

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

    PubMed

    Hack, Tay

    2014-04-01

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

  9. Impression formation and revision in social anxiety disorder.

    PubMed

    Haker, Ayala; Aderka, Idan M; Marom, Sofi; Hermesh, Haggai; Gilboa-Schechtman, Eva

    2014-03-01

    Interpersonal relations are markedly impaired in social anxiety. Yet, little is known about the ways social anxiety affects social cognition. We examined impression formation and impression revision among individuals with social anxiety disorder (SAD, n = 26) and non-anxious individuals (n = 29). Participants read initial descriptions of protagonists depicted as dominant, neutral or submissive and rated them on social rank and affiliation dimensions. Next, participants were presented with behavioral acts that were either congruent, incongruent or irrelevant to the initial descriptions, and re-rated the protagonists. Individuals with SAD (a) rated others as more extreme on social rank dimension, (b) rated others as lower on the affiliation dimension, and (c) revised their impressions of others to a greater extent than did the non-anxious individuals. Understanding the ways social anxiety affects the formation and revision of perceptions of others can improve our understanding of maintaining processes in SAD. PMID:23774009

  10. Preliminary results from disinfection of irreversible hydrocolloid impressions.

    PubMed

    Look, J O; Clay, D J; Gong, K; Messer, H H

    1990-06-01

    The virucidal efficacy of germicides acting on an irreversible hydrocolloid surface is not known. Tests that are currently performed on germicides do not simulate the conditions under which the germicides are often used. One major concern for the dental profession is the disinfection of dental impressions, particularly irreversible hydrocolloid impressions. This study was designed to test the biocidal action of germicides against an enveloped virus on an irreversible hydrocolloid surface. The disinfection model, which was developed to simulate clinical conditions, specified the use of vesicular stomatitus virus, an animal virus amenable to safe handling. A 0.5% sodium hypochlorite spray inactivated the virus when the spray was allowed to remain on the impression 3 to 10 minutes. The iodophor disinfectant required a 3- to 10-minute immersion for total inactivation. Although 2% glutaraldehyde achieved total viral inactivation in less than 1 minute, the authors conclude that short disinfectant sprays, in general, are not an appropriate disinfection method. PMID:2163446

  11. The quality of impressions for crowns and bridges: an assessment of the work received at three commercial dental laboratories. assessing the quality of the impressions of prepared teeth.

    PubMed

    Storey, D; Coward, T J

    2013-06-01

    The literature is limited in studies directly assessing the quality of impressions for crowns and bridges in the UK. The aim of the study was to assess the quality of impressions for conventional crown and bridgework received by commercial dental laboratories. Three dental laboratories were visited over a 3-month period. All impressions for conventional crowns and bridges that arrived on the days of the visits were examined prior to any laboratory processing. A total of 206 impression cases were examined and assessed against criteria laid out in a custom-designed assessment form. Defects were commonly found in the recording of prepared teeth. Overall, 44.2% of impression cases were unsatisfactory. NHS impressions were more than twice as likely to be unsatisfactory compared to private impressions. If the results of this survey are typical then the general quality of impressions for fixed crown and bridgework is unacceptable. This is particularly true for work completed under the NHS contract. PMID:23888527

  12. Polyvinylidene fluoride/siloxane nanofibrous membranes for long-term continuous CO2 -capture with large absorption-flux enhancement.

    PubMed

    Lin, Yi-Feng; Wang, Chi-Sen; Ko, Chia-Chieh; Chen, Chien-Hua; Chang, Kai-Shiun; Tung, Kuo-Lun; Lee, Kueir-Rarn

    2014-02-01

    In a CO2 membrane contactor system, CO2 passes through a hydrophobic porous membrane in the gas phase to contact the amine absorbent in the liquid phase. Consequently, additional CO2 gas is absorbed by amine absorbents. This study examines highly porous polyvinylidene fluoride (PVDF)/siloxane nanofibrous layers that are modified with hydrophobic fluoroalkylsilane (FAS) functional groups and successfully coated onto a macroporous Al2 O3 membrane. The performance of these materials in a membrane contactor system for CO2 absorption is also investigated. Compared with pristine PVDF nanofibrous membranes, the PVDF/siloxane nanofibrous membranes exhibit greater solvent resistance and mechanical strength, making them more suitable for use in CO2 capture by the membrane contactor. The PVDF/siloxane nanofibrous layer in highly porous FAS-modified membranes can prevent the wetting of the membrane by the amine absorbent; this extends the periods of continuous CO2 absorption and results in a high CO2 absorption flux with a minimum of 500 % enhancement over that of the uncoated membranes. This study suggests the potential use of an FAS-modified PVDF/siloxane nanofibrous membrane in a membrane contactor system for CO2 absorption. The resulting hydrophobic membrane contactor also demonstrates the potential for large-scale CO2 absorption during post-combustion processes in power plants. PMID:24194500

  13. Poly(dimethyl siloxane) surface modification by low pressure plasma to improve its characteristics towards biomedical applications

    Microsoft Academic Search

    S. Pinto; P. Alves; C. M. Matos; A. C. Santos; L. R. Rodrigues; J. A. Teixeira; M. H. Gil

    2010-01-01

    Poly(dimethyl siloxane) elastomer, (PDMS) is widely used as a biomaterial. However, PDMS is very hydrophobic and easily colonized by several bacteria and yeasts. Consequently, surface modification has been used to improve its wettability and reduce bacterial adhesion.The aim of this work was to modify the PDMS surface in order to improve its hydrophilicity and bacterial cell repulsion to be used

  14. Polyvinyl alcohol cross-linked with two aldehydes

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  15. 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.

  16. Macroporous polymeric hydrogels formed from acrylate modified polyvinyl alcohol macromers

    Microsoft Academic Search

    Alexander A. Artyukhov; Mikhail I. Shtilman; Andrey N. Kuskov; Anna P. Fomina; Denis E. Lisovyy; Anna S. Golunova; Aristidis M. Tsatsakis

    2011-01-01

    Macroporous polymeric hydrogels for the last several years have found broad application in areas connected with medicine,\\u000a especially in such new disciplines as cell and tissue engineering. In present work a novel combine approach is proposed for\\u000a preparation of polyvinyl alcohol macroporous hydrogels by cross-linking of polyvinyl alcohol acrylic derivatives in the presence\\u000a of heterophase of frozen aqueous media. Hydrogels

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

    PubMed

    Tansel, Berrin; Surita, Sharon C

    2014-11-01

    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. PMID:25160660

  18. Trophic transfer of methyl siloxanes in the marine food web from coastal area of northern china.

    PubMed

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

    2015-03-01

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

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

    Microsoft Academic Search

    Anne Reyers; Jonathan Matusitz

    2012-01-01

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

  20. Modeling first impressions from highly variable facial images

    PubMed Central

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

    2014-01-01

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

  1. Mediterranean Impressions FREE AIRFARE*2-FOR-1 CRUISE FARES

    E-print Network

    Mather, Patrick T.

    Mediterranean Impressions FREE AIRFARE*2-FOR-1 CRUISE FARES BARCELONA · MARSEILLE/PROVENCE · MONTE­24, 2015 10-NIGHT LUXURY CRUISE ABOARD MARINA LIMITED TO 24 SPACES! BOOK NOW! 800.842.9023 FROM $5,299 PER Barcelona to Rome aboard Oceania Cruises' beautiful ship Marina, a masterpiece of elegance and grace

  2. Impressions of a Middle Grades STEM Integration Program

    ERIC Educational Resources Information Center

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

    2011-01-01

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

  3. Forming On-Line Impressions: A Class Exercise

    ERIC Educational Resources Information Center

    Bishop-Clark, Cathy; Dietz-Uhler, Beth

    2003-01-01

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

  4. A dress to impress: ordered melanin layers produce seductively shiny

    E-print Network

    57 ChapTer 5 A dress to impress: ordered melanin layers produce seductively shiny occipital is produced by ordered melanin pigmentation to produce a multilayer interference reflector. The parotia's feather barbules contain 6-7 layers of densely packed melanin rodlets (diameter ~0.25 m, length ~2 m

  5. Modeling first impressions from highly variable facial images.

    PubMed

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

    2014-08-12

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

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

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

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

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

    ERIC Educational Resources Information Center

    Spong, Abigail; Kamau, Caroline

    2012-01-01

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

  8. Impressions of Former Participants Since 2010, "Engineering and Management across

    E-print Network

    Wu, Yih-Min

    Impressions of Former Participants Since 2010, "Engineering and Management across Cultures" has München. "I attended Engineering and Management across Cultu- res and it's a really unforgettable sommeruni@zv.tum.de www.tum-summer.com August 05 - August 25, 2013 Engineering and Management across

  9. 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 ?g 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

  10. 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.

  11. Liquid-phase-deposited siloxane-based capping layers for silicon solar cells

    NASA Astrophysics Data System (ADS)

    Veith-Wolf, Boris; Wang, Jianhui; Hannu-Kuure, Milja; Chen, Ning; Hadzic, Admir; Williams, Paul; Leivo, Jarkko; Karkkainen, Ari; Schmidt, Jan

    2015-02-01

    We apply non-vacuum processing to deposit dielectric capping layers on top of ultrathin atomic-layer-deposited aluminum oxide (AlOx) films, used for the rear surface passivation of high-efficiency crystalline silicon solar cells. We examine various siloxane-based liquid-phase-deposited (LPD) materials. Our optimized AlOx/LPD stacks show an excellent thermal and chemical stability against aluminum metal paste, as demonstrated by measured surface recombination velocities below 10 cm/s on 1.3 ?cm p-type silicon wafers after firing in a belt-line furnace with screen-printed aluminum paste on top. Implementation of the optimized LPD layers into an industrial-type screen-printing solar cell process results in energy conversion efficiencies of up to 19.8% on p-type Czochralski silicon.

  12. Poly(dimethyl siloxane) membrane for high temperature proton exchange membrane fuel cells.

    PubMed

    Ghil, Lee-Jin; Kim, Chang-Kyeom; Kang, Jung-Soo; Kim, Young-Taek; Rhee, Hee-Woo

    2009-12-01

    Sulfonic acid-based membrane gives the relatively high conductivity only in the presence of water, but phosphoric acid presents the relatively high proton conductivity without water because of its self dissociation natures to develop high temperature PEMFCs. We synthesized the thermostable material that has phosphorous groups based on poly(dimethyl siloxane) (PDMS). PDMS, which is intrinsically hydrophobic was modified to be amphiphilic by substituting end groups with hydrophilic phosphorous groups. Phase separation resulted in forming the proton conducting channels. The membranes maintained the constant proton conductivity above 130 degrees C under dry conditions. Also they were thermally stable up to 300 degrees C and may be used as high temperature proton conducting membrane at low humid conditions. PMID:19908698

  13. Regeneration of siloxane-exhausted activated carbon by advanced oxidation processes.

    PubMed

    Cabrera-Codony, Alba; Gonzalez-Olmos, Rafael; Martín, Maria J

    2015-03-21

    In the context of the biogas upgrading, siloxane exhausted activated carbons need to be regenerated in order to avoid them becoming a residue. In this work, two commercial activate carbons which were proved to be efficient in the removal of octamethylcyclotetrasiloxane (D4) from biogas, have been regenerated through advanced oxidation processes using both O3 and H2O2. After the treatment with O3, the activated carbon recovered up to 40% of the original adsorption capacity while by the oxidation with H2O2 the regeneration efficiency achieved was up to 45%. In order to enhance the H2O2 oxidation, activated carbon was amended with iron. In this case, the regeneration efficiency increased up to 92%. PMID:25553386

  14. An Investigation of Siloxane Cross-linked Hydroxyapatite-Gelatin/Copolymer Composites for Potential Orthopedic Applications†

    PubMed Central

    Dyke, Jason Christopher; Knight, Kelly Jane; Zhou, Huaxing; Chiu, Chi-Kai; Ko, Ching-Chang; You, Wei

    2012-01-01

    Causes of bone deficiency are numerous, but biomimetic alloplastic grafts provide an alternative to repair tissue naturally. Previously, a hydroxyapatite-gelatin modified siloxane (HAp-Gemosil) composite was prepared by cross-linking (N, N?-bis[(3-trimethoxysilyl)propyl]ethylene diamine (enTMOS) around the HAp-Gel nanocomposite particles, to mimic the natural composition and properties of bone. However, the tensile strength remained too low for many orthopedic applications. It was hypothesized that incorporating a polymer chain into the composite could help improve long range interaction. Furthermore, designing this polymer to interact with the enTMOS siloxane cross-linked matrix would provide improved adhesion between the polymer and the ceramic composite, and improve mechanical properties. To this end, copolymers of L-Lactide (LLA), and a novel alkyne derivatized trimethylene carbonate, propargyl carbonate (PC), were synthesized. Incorporation of PC during copolymerization affects properties of copolymers such as molecular weight, Tg, and % PC incorporation. More importantly, PC monomers bear a synthetic handle, allowing copolymers to undergo post-polymerization functionalization with graft monomers to specifically tailor the properties of the final composite. For our investigation, P(LLA-co-PC) copolymers were functionalized by an azido-silane (AS) via copper catalyzed azide-alkyne cycloaddition (CuAAC) through terminal alkyne on PC monomers. The new functionalized polymer, P(LLA-co-PC)(AS) was blended with HAp-Gemosil, with the azido-silane linking the copolymer to the silsesquioxane matrix within the final composite. These HAp-Gemosil/P(LLA-co-PC)(AS) composites were subjected to mechanical and biological testing, and the results were compared with those from the HAp-Gemosil composites. This study revealed that incorporating a cross-linkable polymer served to increase the flexural strength of the composite by 50%, while maintaining the biocompatibility of HAp-Gemosil ceramics. PMID:23139457

  15. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...polyvinyl chloride plants. An owner or operator...polyvinyl chloride plant shall comply with...postpolymerization. (3) Manual vent valve discharge...atmosphere from any manual vent valve...the reactor if the plant has no...

  16. Finite Element Analysis of Plastic Deformation During Impression Creep

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  17. Finite Element Analysis of Plastic Deformation During Impression Creep

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  18. First impressions: towards becoming a health-literate health service.

    PubMed

    Johnson, Anne

    2014-05-01

    A 'health-literate organisation' recognises that miscommunication is very common and can negatively affect consumer care and outcomes, and makes it easier for people to navigate, understand, and use health information and services. This paper reports on the First Impressions Activities conducted by consumers to assess aspects of the literacy environment of a rural health service. The First Impressions Activities consists of three tools to assist health services to begin to consider some of the characteristics of their organisation that help and hinder a consumer's ability to physically navigate their way to and about the health service. The results show that navigation to and within the rural health service was made more complex due to lack of information, difficulty finding information, inconsistent terminology used in signage, missing signage, signage obscured by foliage, and incorrect signage. PMID:24670250

  19. Impression Material Mass Retained in the Mucobuccal Fold

    PubMed Central

    Karam Genno, N.; Assaf, A.

    2014-01-01

    Trapped foreign bodies and tissue reactions to foreign materials are commonly encountered in the oral cavity. Traumatically introduced dental materials, instruments, or needles are the most common materials referred to in the dental literature. This paper describes an iatrogenic foreign body encapsulation in the oral mucosa, clinically appearing as 5 × 10?mm tumor-like swelling with an intact overlying epithelium and diagnosed as a polymeric impression material. Detailed case history and, clinical and radiographic examinations including CBCT and spectrometric analysis of the retrieved sample were necessary to determine accurately the nature, size, and location of the foreign body. It is suggested that the origin of the material relates to an impression made 2 years ago, leaving a mass trapped in a traumatized mucosal tissue. PMID:25061529

  20. Relation between impressions of a touch panels’ coloration and operation

    Microsoft Academic Search

    Makiba Sakamoto; Hidetsugu Suto; Masahiro Sawai

    2010-01-01

    The relationships between the colors used in the design of touch panels and the operation of electronic devices are discussed,\\u000a and experiments that investigated the effects of color in the designs of touch panel interfaces on their operation and on\\u000a the impressions of users have been conducted. Subjects tried mental arithmetic tests on 12 types of screen which had different

  1. Sterilization analysis of contaminated healing abutments and impression copings.

    PubMed

    Browne, Vanessa; Flewelling, Michael; Wierenga, Mark; Wilson, Alisa; Aprecio, Ray; Richardson, Paul; Angelov, Nikola; Johnson, Neal

    2012-05-01

    This study investigated sterilization of used implant impression copings and healing abutments. Components were analyzed after contamination with Enterococcus foecalis, followed by multiple rounds of sterilization by both steam autoclave and Chemiclave protocols. The authors' results demonstrated that used components showed sterility equal to new components without any visible distortion. These data suggest that component resterilization and reuse may be justified or at least considered in clinical practice. Also, implications for cost savings in the placement of implants are advanced. PMID:22685949

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

    PubMed

    Biermann, Ursula; Metzger, Jürgen O

    2014-02-01

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

  3. Radiation-chemical preparation of poly(vinyl alcohol) hydrogels

    NASA Astrophysics Data System (ADS)

    Duflot, Anastasia V.; Kitaeva, Natalia K.; Duflot, Vladimir R.

    2015-02-01

    This work reports the usage of method of radiation-chemical synthesis to prepare cross-linked hydrogels from poly(vinyl alcohol) modified with glycidyl methacrylate. Synthesis kinetics of modified poly(vinyl alcohol) and properties of hydrogels were studied. The gel fraction, swelling, mechanical properties, and water content of the hydrogels were measured. It was found that gel fraction increases with increasing radiation dose, concentration of modified poly(vinyl alcohol), and reaches 60%. It was established by differential scanning calorimetry that a fraction of the 'bound' water in hydrogels is 50-70% and independent of gel fraction content. In addition to 'bound' and 'free' states, water in hydrogels is also present in the intermediate state.

  4. Appearing smart: the impression management of intelligence, person perception accuracy, and behavior in social interaction.

    PubMed

    Murphy, Nora A

    2007-03-01

    Intelligence is an important trait that affects everyday social interaction. The present research utilized the ecological perspective of social perception to investigate the impression management of intelligence and strangers' evaluations of targets' intelligence levels. The ability to effectively portray an impression of intelligence to outside judges as well as interaction partners was appraised and the effect of impression management on the accurate judgment of intelligence was assessed. In addition, targets' behavior was studied in relation to impression management, perceived intelligence, and actual measured intelligence. Impression-managing targets appeared more intelligent to video judges but not to their interaction partner as compared to controls. The intelligence quotient (IQ) of impression-managing targets was more accurately judged than controls' IQ. Impression-managing targets displayed distinct nonverbal behavioral patterns that differed from controls. Looking while speaking was a key behavior: It significantly correlated with IQ, was successfully manipulated by impression-managing targets, and contributed to higher perceived intelligence ratings. PMID:17312315

  5. Impression management in initial social interaction and its effect on the self-concept 

    E-print Network

    Mi, Ting

    2012-11-28

    Impression management plays a key part in social interaction. But its effects on self-concept change are merely studied. So this study investigates whether impression management will affect peoples‘ self-concept based on two-component model...

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

    PubMed

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

    2014-02-17

    Siloxanes and trimethylsilanol belong to a family of organic silicone compounds that are currently used extensively in industry. Those that are prone to volatilisation become minor compounds in biogas adversely affecting energetic applications. However, non-standard analytical methodologies are available to analyse biogas-based gaseous matrixes. To this end, different sampling techniques (adsorbent tubes, impingers and tedlar bags) were compared using two different configurations: sampling directly from the biogas source or from a 200 L tedlar bag filled with biogas and homogenised. No significant differences were apparent between the two sampling configurations. The adsorbent tubes performed better than the tedlar bags and impingers, particularly for quantifying low concentrations. A method for the speciation of silicon compounds in biogas was developed using gas chromatography coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimised conditions could separate and quantify eight siloxane compounds (L2, L3, L4, L5, D3, D4, D5 and D6) and trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain, France and England was sampled and analysed using the developed methodology. The siloxane concentrations in the biogas samples were influenced by the anaerobic digestion temperature, as well as the nature and composition of the sewage inlet. Siloxanes D4 and D5 were the most abundant, ranging in concentration from 1.5 to 10.1 and 10.8 to 124.0 mg Nm(-3), respectively, and exceeding the tolerance limit of most energy conversion systems. PMID:24491768

  7. Oxidation of siloxanes during biogas combustion and nanotoxicity of Si-based particles released to the atmosphere.

    PubMed

    Tansel, Berrin; Surita, Sharon C

    2014-01-01

    Siloxanes have been detected in the biogas produced at municipal solid waste landfills and wastewater treatment plants. When oxidized, siloxanes are converted to silicon oxides. The objectives of this study were to evaluate the transformation of siloxanes and potential nanotoxicity of Si-based particles released to the atmosphere from the gas engines which utilize biogas. Data available from nanotoxicity studies were used to assess the potential health risks associated with the inhalation exposure to Si-based nanoparticles. Silicon dioxide formed from siloxanes can range from 5 nm to about 100 nm in diameter depending on the combustion temperature and particle clustering characteristics. In general, silicon dioxide particles formed during from combustion process are typically 40-70 nm in diameter and can be described as fibrous dusts and as carcinogenic, mutagenic, astmagenic or reproductive toxic (CMAR) nanoparticles. Nanoparticles deposit in the upper respiratory system, conducting airways, and the alveoli. Size ranges between 5 and 50 nm show effective deposition in the alveoli where toxic effects are higher. In this study the quantities for the SiO? formed and release during combustion of biogas were estimated based on biogas utilization characteristics (gas compositions, temperature). The exposure to Si-based particles and potential effects in humans were analyzed in relation to their particle size, release rates and availability in the atmosphere. The analyses showed that about 54.5 and 73 kg/yr of SiO? can be released during combustion of biogas containing D4 and D5 at 14.1 mg/m(3) (1 ppm) and 15.1 mg/m(3) (1ppm), respectively, per MW energy yield. PMID:24355797

  8. Synthesis and characterization of organic-inorganic hybrid clay filled and bismaleimide—siloxane modified epoxy nanocomposites

    Microsoft Academic Search

    Selvaganapathi Anbazhagan; Muthukaruppan Alagar; Periyannan Gnanasundaram

    Organic-inorganic hybrids involving organo-modified montmorillonite (OMMT) clay and tetraglycidyl diamino diphenyl methane\\u000a epoxy (TGDDM) were prepared via in situ polymerization by the homogeneous dispersion of various percentages (1–5% w\\/w) of\\u000a clay in epoxy matrix resin. The resulting homogeneous epoxy—clay hybrids were modified with 10 wt% of hydroxyl terminated\\u000a polydiemthyl siloxane (HTPDMS) using ?—aminopropyltriethoxysilane (?-APS) as coupling agent in the presence of

  9. Strength of modified polyvinyl chloride films taking account of operating conditions

    Microsoft Academic Search

    É. S. Umanskii; N. S. Shidlovskii; L. L. Stezhko; V. V. Kryuchkov; V. L. Nikityuk

    1990-01-01

    Experimental data are given for the strength and deformability of a wide range of polyvinyl chloride films obtained by combining different grades of polyvinyl chlorides and modifiers. The effect is considered of temperature and longterm climatic factors on the strength of these materials. The possibility is demonstrated of predicting the change in deformability of polyvinyl chloride films under conditions of

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

    E-print Network

    Mather, Patrick T.

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

  11. Effect of Microwave Irradiation on the Cross-Linking of Polyvinyl Alcohol

    Microsoft Academic Search

    N. V. Petrova; A. M. Evtushenko; I. P. Chikhacheva; V. P. Zubov; I. V. Kubrakova

    2005-01-01

    The possibility of dehydration (cross-linking) of polyvinyl alcohol upon microwave irradiation of thin polymer films was examined. The properties of polyvinyl alcohol samples treated by convection heating and irradiation were compared. Immobilization of polyvinyl alcohol on polymer matrices by microwave irradiation was studied.

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

    NASA Technical Reports Server (NTRS)

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

    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.

  13. Photooxidative degradation of carboxylated poly(vinyl chloride)

    Microsoft Academic Search

    Halina Kaczmarek; Agnieszka Felczak; Dagmara Bajer

    2009-01-01

    Thin films of poly(vinyl chloride), PVC, and carboxylated poly(vinyl chloride), C-PVC, containing 1.8% of carboxyl groups\\u000a were exposed to high energy ultraviolet radiation (? = 254 nm) in laboratory conditions. The photochemical reactions in irradiated\\u000a samples were studied by FTIR and UV–Vis spectroscopy, gel permeation chromatography and gravimetric estimation of insoluble\\u000a gel. It was found that photodegradation and photocrosslinking in C-PVC is accelerated,

  14. Why Most People Disapprove of Me: Experience Sampling in Impression Formation

    ERIC Educational Resources Information Center

    Denrell, Jerker

    2005-01-01

    Individuals are typically more likely to continue to interact with people if they have a positive impression of them. This article shows how this sequential sampling feature of impression formation can explain several biases in impression formation. The underlying mechanism is the sample bias generated when the probability of interaction depends…

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

    ERIC Educational Resources Information Center

    Van Der Heide, Brandon Lee

    2009-01-01

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

  16. Managing and Creating an Image in the Interview: The Role of Interviewee Initial Impressions

    ERIC Educational Resources Information Center

    Swider, Brian W.; Barrick, Murray R.; Harris, T. Brad; Stoverink, Adam C.

    2011-01-01

    In employment interviews, individuals use impression management tactics to present themselves as suitable candidates to interviewers. However, not all impression management tactics, or the interviewees who employ them, are effective at positively influencing interview scores. Results of this study indicate that the relationship between impression

  17. Influence of impression management on interpersonal citizenship behavior: Leader-member exchange as a mediator

    Microsoft Academic Search

    Shereen Noranee; Noormala Dato'Amir Ishak; Raja Munirah Raja Mustapha

    2012-01-01

    This paper formulates a framework postulating impression management (IM) as an antecedent of two complementary forms of interpersonal citizenship behavior (ICB), namely task-focused and person-focused. Employees who are motivated by impression management perform ICB to obtain desired rewards and avoid undesired outcomes. Even though ICBs are viewed as prosocial behavior not impression management, a process by which people control the

  18. The polyvinyl alcohol sponge model implantation.

    PubMed

    Deskins, Desirae L; Ardestani, Shidrokh; Young, Pampee P

    2012-01-01

    Wound healing is a complicated, multistep process involving many cell types, growth factors and compounds(1-3). Because of this complexity, wound healing studies are most comprehensive when carried out in vivo. There are many in vivo models available to study acute wound healing, including incisional, excisional, dead space, and burns. Dead space models are artificial, porous implants which are used to study tissue formation and the effects of substances on the wound. Some of the commonly used dead space models include polyvinyl alcohol (PVA) sponges, steel wire mesh cylinders, expanded polytetrafluoroethylene (ePTFE) material, and the Cellstick(1,2). Each dead space model has its own limitations based on its material's composition and implantation methods. The steel wire mesh cylinder model has a lag phase of infiltration after implantation and requires a long amount of time before granulation tissue formation begins(1). Later stages of wound healing are best analyzed using the ePTFE model(1,4). The Cellstick is a cellulose sponge inside a silicon tube model which is typically used for studying human surgery wounds and wound fluid(2). The PVA sponge is limited to acute studies because with time it begins to provoke a foreign body response which causes a giant cell reaction in the animal(5). Unlike other materials, PVA sponges are easy to insert and remove, made of inert and non-biodegradable materials and yet are soft enough to be sectioned for histological analysis(2,5). In wound healing the PVA sponge is very useful for analyzing granulation tissue formation, collagen deposition, wound fluid composition, and the effects of substances on the healing process(1,2,5). In addition to its use in studying a wide array of attributes of wound healing, the PVA sponge has also been used in many other types of studies. It has been utilized to investigate tumor angiogenesis, drug delivery and stem cell survival and engraftment(1,2,6,7). With its great alterability, prior extensive use, and reproducible results, the PVA sponge is an ideal model for many studies(1,2). Here, we will describe the preparation, implantation and retrieval of PVA sponge disks (Figure 1) in a mouse model of wound healing. PMID:22546933

  19. Anammox sludge immobilized in polyvinyl alcohol (PVA) cryogel carriers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the use of polyvinyl alcohol (PVA) cryogels to encapsulate slow-growing anammox bacteria for deammonification treatment of wastewater. The cryogel pellets were prepared by a freezing-thawing procedure at -8 oC. On average, pellets contained 11.8 mg TSS/g-pellet of enriched anamm...

  20. EXPOSURE TO CHEMICAL ADDITIVES FROM POLYVINYL CHLORIDE POLYMER EXTRUSION PROCESSING

    EPA Science Inventory

    This report presents a model to predict worker inhalation exposure due to off-gassing of additives during polyvinyl chloride (PVC) extrusion processing. ata on off-gassing of additives were reviewed in the literature, the off-gassing at normal PVC processing temperatures was stud...

  1. 1 INTRODUCTION In Spain, Plasticized polyvinyl chloride (PVC-

    E-print Network

    Zornberg, Jorge G.

    1 INTRODUCTION In Spain, Plasticized polyvinyl chloride (PVC- P) geomembranes began being used in waterproof- ing of infrastructure in the seventies. Early usage of PVC-P geomembranes was not particularly for the PVC-P homogeneous geomem- branes used in roofing. Subsequently, other stan- dards were drafted

  2. Flow-induced swelling of poly(vinyl alcohol) gel

    Microsoft Academic Search

    T. Takigawa; K. Uchida; K. Takahashi; T. Masuda

    1999-01-01

    Flow and swelling behavior was investigated for poly(vinyl alcohol) (PVA) gel in the solvent flow field. It was found that the PVA gel swelled under solvent flow and the volume of the gel increased with increasing solvent pressure. The flow rate also increased with increasing solvent pressure. On the other hand, the characteristic times determined by swelling and flow kinetics

  3. Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry

    Microsoft Academic Search

    Munzer Kattan; Haroun al Kassiri; Yarob Daher

    2011-01-01

    Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417nm depends linearly on the dose below 50kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed.

  4. Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry.

    PubMed

    Kattan, Munzer; al Kassiri, Haroun; Daher, Yarob

    2011-02-01

    Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417 nm depends linearly on the dose below 50 kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed. PMID:21109445

  5. Lung function in workers exposed to polyvinyl chloride dust

    Microsoft Academic Search

    C P Chivers; C Lawrence-Jones; G M Paddle

    1980-01-01

    Several reported studies on the effects of polyvinyl chloride (PVC) dust in animals and man have been conflicting. The present study of the ventilatory function of 509 male workers exposed to PVC dust was made in 1977. Altogether 104 men exposed to PVC dust only, 112 men exposed to non-chlorinated solvents only, and 293 men exposed to a mixture of

  6. Immobilization of enzymes in photochemically cross-linked polyvinyl alcohol

    Microsoft Academic Search

    Thomas Uhlich; Mathias Ulbricht; Georg Tomaschewski

    1996-01-01

    Invertase and amyloglucosidase were entrapped in polyvinyl alcohol membranes through UV irradiation of pendent styrylpyridinium groups. The influence of cross-linking on immobilization efficiency was studied using prepolymers with varied cross-linker density, the above mentioned enzymes of different molecular weight, and various substrates. It was found that the larger enzyme invertase is effectively immobilized even in polymers with very low contents

  7. Novel Low Flammable Coating Based on Polyvinyl Alcohol

    Microsoft Academic Search

    Guennadi E. Zaikov; Sergei M. Lomakin

    1997-01-01

    A new type of polymer varnish (coating) based on Polyvinyl Alcohol was developed using potassium permanganate oxidation in water solution. The flammability of this coating was tested using Cone Calorimeter. All tests on flammability indicated an increase of flame retardancy of this polymer coating due to carbonization of cross-linked polymer fragments.

  8. Pilot study on accuracy and dimensional stability of impression materials using industrial CT technology

    Microsoft Academic Search

    Stefanie Steinhäuser-Andresen; Andreas Detterbeck; Christoph Funk; Michael Krumm; Stefan Kasperl; Alexandra Holst; Ursula Hirschfelder

    2011-01-01

    Objective  Using computed tomography, scan impressions can be saved and edited as virtual data. The aim of this study was to evaluate\\u000a the parameters influencing different impression materials and impression trays and their relevance with regard to accuracy\\u000a and dimensional stability.\\u000a \\u000a \\u000a \\u000a \\u000a Materials and methods  Two alginate impressions (Zhermack Hydrogum®5 and Kaniedenta Tetrachrom®) and a polyether impression (3MEspe Impregum™) were\\u000a each combined with

  9. Isolation of microRNA from conjunctival impression cytology.

    PubMed

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

    2015-03-01

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

  10. Piezoresistance characterization of poly(dimethyl-siloxane) and poly(ethylene) carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Rizvi, Reza; Cochrane, Brendan; Biddiss, Elaine; Naguib, Hani

    2011-09-01

    This study examines the piezoresistive behavior of polymer-carbon nanotube composites. Piezoresistive composites of poly(dimethyl-siloxane) (PDMS) and poly(ethylene) (PE) filled with multiwall carbon nanotubes (MWNTs) were prepared. The morphology and the electrical conductivity of the composites were characterized at various MWNT compositions. The percolation threshold was found to be 3 wt% for PDMS composites and 2.2 wt% for PE composites. The piezoresistive behavior under compression was measured using a setup comprised of a mechanical tester and a digital sourcemeter. Negative piezoresistive behavior was observed, signifying a reducing mean interparticulate distance in the composites. The PE-MWNT composites were found to be more sensitive than the PDMS composites (97% versus 78% change in resistance), which was attributed to the dissimilar morphologies as a result of difference in processing. Increasing the MWNT concentration in the PE composites resulted in decreasing the sensitivity to stress. The results were found to fit well to a modified version of a piezoresistance model. PDMS and PE composites were found to have different piezoresistance behavior during stress relaxation and cyclic loading. The resistance of PE, in comparison to PDMS, was less prone to changes in stress during stress relaxation and exhibited greater sensitivity and less drift during cyclic loading.

  11. Some possibilities to reduce the biofilm formation on transparent siloxane coatings.

    PubMed

    Akuzov, D; Brümmer, F; Vladkova, T

    2013-04-01

    Presence of biofilms is a significant problem to a variety of industrial areas, underwater sensors, shipping, etc. Therefore solutions are sought to inhibit biofilm formation and to permit biofilm removal. Surface modification by suitable coating could be one of them. The present study reports the potential of new transparent biocides-free siloxane antifouling coatings, containing low toxic additives, such as TiO(2) nanoparticles, surfactants and antioxidants, to reduce biofilm formation in mimicking marine environment, laboratory conditions. As evaluated with several parameters: chlorophyll content, carotenoids content, total protein and total dry mass, the biofilm formation was most sharply reduced by the composition coatings containing non-ionic surfactant, super spreader Y17112, followed by those containing antioxidant, ?-tocopherol. Depending on the amount of the super spreader (0.1-1.0 wt.%) and the tested parameter, approximately 3-8-fold reduction was observed in the biofilm formation. It is supposed, that the effect of the studied additives, both surfactant and antioxidant, is due to some inhibition of the adhesive extra cellular substances cross-linking with impact onto the biofilm cohesion strength and its adhesion. PMID:23333915

  12. Nonfunctionalized Polydimethyl Siloxane Superhydrophobic Surfaces Based on Hydrophobic-Hydrophilic Interactions

    SciTech Connect

    Polizos, Georgios [Oak Ridge National Laboratory (ORNL); Tuncer, Enis [ORNL; Qiu, Xiaofeng [ORNL; Aytug, Tolga [ORNL; Kidder, Michelle [ORNL; Messman, Jamie M [ORNL; Sauers, Isidor [ORNL

    2011-01-01

    Superhydrophobic surfaces based on polydimethyl siloxane (PDMS) were fabricated using a 50:50 PDM-poly(ethylene glycol) (PEG) blend. PDMS was mixed with PEG, and incomplete phase separation yielded a hierarchic structure. The phase-separated mixture was annealed at a temperature close to the crystallization temperature of the PEG. The PEG crystals were formed isothermally at the PDMS/PEG interface, leading to an engineered surface with PDMS spherulites. The resulting roughness of the surface was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The PDMS spherulites, a few micrometers in diameter observed from SEM images, were found to have an undulated (rippled) surface with nanometer-sized features. The combination of micrometer- and nanometer-sized surface features created a fractal surface and increased the water contact angle (WCA) of PDMS more than 60, resulting in a superhydrophobic PDMS surface with WCA of >160 degrees. The active surface layer for the superhydrophobicity was approximately 100 mu m thick, illustrating that the material had bulk superhydrophobicity compared to conventional fluorocarbon or fluorinated coated rough surfaces. Theoretical analysis of the fractal surface indicates that the constructed surface has a fractal dimension of 2.5, which corresponds to the Apollonian sphere packing.

  13. Novel gelatin siloxane nanoparticles decorated by Tat peptide as vectors for gene therapy

    NASA Astrophysics Data System (ADS)

    Wang, Zu-yong; Zhao, Yang; Ren, Lei; Jin, Li-hua; Sun, Li-ping; Yin, Pei; Zhang, Ya-fei; Zhang, Qi-Qing

    2008-11-01

    In principle, the technique of gene delivery involves taking complete or parts of genes that can code specific messages and delivering them to selected cells in the body. Such a transfer of plasmid DNA into mammalian cells has posed major challenges for gene therapy. A series of gelatin-siloxane nanoparticles (GS NPs) with controlled size and surface charge were synthesized through a two-step sol-gel process. In order to increase the efficiency of cellular uptake, HIV-derived Tat peptide was further grafted to GS NPs. In vitro co-location and endocytosis inhibition experiments suggested that the as-synthesized TG NPs may enter HeLa cells via a combined pathway of lipid-raft- and receptor-dependent endocytosis, and only cause little cell damage. Moreover, this study shows the encapsulation of a plasmid DNA in TG NPs to be obtained as a non-viral gene vector. This kind of encapsulation provides complete protection to the plasmid DNA from the external DNase and serum environment, and generates the hope that the resulting formulation can be developed into a potential vector for effective gene delivery. In order to check this potential, the reporter gene pSV?-gal was encapsulated, and in vitro transfection efficiency of this system was found to be nearly 130% compared to the commercially available transfection reagent Lipofectamine™.

  14. Synthesis of a novel multi N-halamines siloxane precursor and its antimicrobial activity on cotton

    NASA Astrophysics Data System (ADS)

    Wu, Lin; Xu, Yan; Cai, Lu; Zang, Xiong; Li, Zhanxiong

    2014-09-01

    A novel N-halamine siloxane antibacterial precursor N-(3-triethoxysilylpropyl)-N?- (N??-heptylcarbamido-N?-ethyl)-butanediamide (TSHCEB) was synthesized and characterized in this study. The compound was then tethered to the surface of cotton fabrics through covalent ether linkages, followed by exposure to dilute sodium hypochlorite solutions to confer the cotton fabrics antibacterial property. The chemical structure of the monomer was confirmed by FTIR, 1H NMR and MS, and the surface of the treated cotton fabrics was characterized by FTIR, TGA, SEM, and XPS analysis. The antimicrobial cotton materials were then challenged with Gram-negative Escherichia coli O157:H7 (ATCC 43895) and Gram-positive Staphylococcus aureus (ATCC 6538). Results showed that it provided excellent antimicrobial properties against E. coli O157:H7 and S. aureus via direct contacting for 2-15 min. The controlled release of diverse chlorines was proved by inhibition zone. The chlorine bonded to the coating was stable under standard washing test and routine storage, stability toward UVA irradiation was also investigated, and the lost chlorine could be regenerated by rechlorination. The new N-halamine antibacterial precursor can provide superior antibacterial property within a short contact time.

  15. Lateral Orbitofrontal Cortex Involvement in Initial Negative Aesthetic Impression Formation

    PubMed Central

    Munar, Enric; Nadal, Marcos; Rosselló, Jaume; Flexas, Albert; Moratti, Stephan; Maestú, Fernando; Marty, Gisèle; Cela-Conde, Camilo J.

    2012-01-01

    It is well established that aesthetic appreciation is related with activity in several different brain regions. The identification of the neural correlates of beauty or liking ratings has been the focus of most prior studies. Not much attention has been directed towards the fact that humans are surrounded by objects that lead them to experience aesthetic indifference or leave them with a negative aesthetic impression. Here we explore the neural substrate of such experiences. Given the neuroimaging techniques that have been used, little is known about the temporal features of such brain activity. By means of magnetoencephalography we registered the moment at which brain activity differed while participants viewed images they considered to be beautiful or not. Results show that the first differential activity appears between 300 and 400 ms after stimulus onset. During this period activity in right lateral orbitofrontal cortex (lOFC) was greater while participants rated visual stimuli as not beautiful than when they rated them as beautiful. We argue that this activity is associated with an initial negative aesthetic impression formation, driven by the relative hedonic value of stimuli regarded as not beautiful. Additionally, our results contribute to the understanding of the nature of the functional roles of the lOFC. PMID:22675517

  16. Ultraviolet light stable and transparent sol-gel methyl siloxane hybrid material for UV light-emitting diode (UV LED) encapsulant.

    PubMed

    Bae, Jun-Young; Kim, YongHo; Kim, HweaYoon; Kim, YuBae; Jin, Jungho; Bae, Byeong-Soo

    2015-01-21

    An ultraviolet (UV) transparent and stable methyl-siloxane hybrid material was prepared by a facile sol-gel method. The transparency and stability of a UV-LED encapsulant is an important issue because it affects UV light extraction efficiency and long-term reliability. We introduced a novel concept for UV-LED encapsulation using a thermally curable oligosiloxane resin. The encapsulant was fabricated by a hydrosilylation of hydrogen-methyl oligosiloxane resin and vinyl-methyl siloxane resin, and showed a comparable transmittance to polydimethylsiloxane (PDMS) in the UVB (?300 nm) region. Most remarkably, the methyl-siloxane hybrid materials exhibited long-term UV stability under light soaking in UVB (?300 nm) for 1000 h. PMID:25564875

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

    NASA Astrophysics Data System (ADS)

    Kavic, Michael; Wiita, P. J.; Benoit, M.; Magee, N.

    2013-01-01

    IMPRESS-Ed is a program designed to provide authentic summer research experiences in the space, earth, and atmospheric sciences for pre-service K-12 educators at Long Island University (LIU) and The College of New Jersey (TCNJ). In 2011 and 2012, the program involved five students and took place over eight weeks with recruitment occurring during the preceding academic year. The program was divided into two modules: A common core module and an individual mentored research experience. The common module consisted of three units focusing on data-driven pedagogical approaches in astrophysics, tectonophysics, and atmospheric science, respectively. The common module also featured training sessions in observational astronomy, and use of a 3D geowall and state of the art planetarium. Participants in the program are also offered the opportunity to utilize the available TCNJ facilities with their future students. The individual mentored research module matched student interests with potential projects. All five students demonstrated strong gains in earth and space science literacy compared to a baseline measurement. Each student also reported gaining confidence to incorporate data and research-driven instruction in the space and earth sciences into the K-12 STEM classroom setting. All five research projects were also quite successful: several of the students plan to continue research during the academic year and two students are presenting research findings as first authors here at AAS. Other research results are likely to be presented at this year's American Geophysical Union meeting.

  18. Structure-property relations in siloxane-based main chain liquid crystalline elastomers and related linear polymers

    NASA Astrophysics Data System (ADS)

    Ren, Wanting

    2007-12-01

    Soft materials have attracted much scientific and technical interest in recent years. In this thesis, attention has been placed on the underpinning relations between molecular structure and properties of one type of soft matter---main chain liquid crystalline elastomers (MCLCEs), which may have application as shape memory or as auxetic materials. In this work, a number of siloxane-based MCLCEs and their linear polymer analogues (MCLCEs) with chemical variations were synthesized and examined. Among these chemical variations, rigid p-phenylene transverse rod and flat-shaped anthraquinone (AQ) mesogenic monomers were specifically incorporated. Thermal and X-ray analysis found a smectic C phase in most of our MCLCEs, which was induced by the strong self-segregation of siloxane spacers, hydrocarbon spacers and mesogenic rods. The smectic C mesophase of the parent LCE was not grossly affected by terphenyl transverse rods. Mechanical studies of MCLCEs indicated the typical three-region stress-strain curve and a polydomain-to-monodomain transition. Strain recovery experiments of MCLCEs showed a significant dependence of strain retentions on the initial strains but not on the chemical variations, such as the crosslinker content and the lateral substituents on mesogenic rods. The MCLCE with p-phenylene transverse rod showed a highly ordered smectic A mesophase at room temperature with high stiffness. Mechanical properties of MCLCEs with AQ monomers exhibit a strong dependence on the specific combination of hydrocarbon spacer and siloxane spacer, which also strongly affect the formation of pi-pi stacking between AQ units. Poisson's ratio measurement over a wide strain range found distinct trends of Poisson's ratio as a function of the crosslinker content as well as terphenyl transverse rod loadings in its parent MCLCEs.

  19. Evaluation of adsorbents for volatile methyl siloxanes sampling based on the determination of their breakthrough volume.

    PubMed

    Lamaa, L; Ferronato, C; Fine, L; Jaber, F; Chovelon, J M

    2013-10-15

    Volatile methyl siloxanes (VMS) have been detected in many different atmospheres such as biogas, sewage sludge, landfill gas, gasoline and ambient air. In these different atmospheres, their presence can involve several contamination problems and negative effects in industrial processes, their identification and quantification become a real challenge. Up to now there is no standardized procedure for VMS quantification, the sampling step remaining the major obstacle. Sampling gas through sorbent tube followed by analysis on TD-GC-MS is one of the reliable possibilities. It gathers sampling and preconcentration in one step and allows discrimination between all VMS, despite the difficulty to choose the appropriate adsorbent in order to avoid loss of analytes during sampling. In this context, this work deals with the comparison of different types of adsorbents based on the determination of the VMS breakthrough volume (BV). Although Tenax TA is the most widely used adsorbent, experiments show low BV values for the lightest VMS. At 25°C, the BV of TMS and L2 are, respectively, 0.2 and 0.44 L g(-1) which can contribute to an underestimation in concentration during their quantification. Carbosieve SIII usually used for C2-C5, did not adsorb light VMS as it was expected, and breakthrough volume obtained for VMS are more than ten times less than the values obtained for Tenax. On other hand, Chromosorb 106 and Carboxen 1000 in association with Carbotrap C and Carbotrap proved to be appropriated for VMS sampling, due to the high breakthrough volumes obtained for the lightest compounds comparing to the other adsorbents. The BVs of TMS for Carboxen 1000 and Chromosorb 106 are 1.2 × 10(4) and 39 L g(-1), respectively, and 49 × 10(4) and 1142 L g(-1) for L2, respectively. PMID:24054678

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

    PubMed

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

    2008-10-01

    Hexamethyldisiloxane (HMDSO) has been identified as a sensitive proton NMR indicator of tissue oxygenation (pO(2)) based on spectroscopic spin-lattice relaxometry. A rapid MRI approach has now been designed, implemented, and tested. The technique, proton imaging of siloxanes to map tissue oxygenation levels (PISTOL), utilizes frequency-selective excitation of the HMDSO resonance and chemical-shift selective suppression of residual water signal to effectively eliminate water and fat signals and pulse-burst saturation recovery (1)H echo planar imaging to map T(1) of HMDSO and hence pO(2). PISTOL was used here to obtain maps of pO(2) in rat thigh muscle and Dunning prostate R3327 MAT-Lu tumor-implanted rats. Measurements were repeated to assess baseline stability and response to breathing of hyperoxic gas. Each pO(2) map was obtained in 3(1/2) min, facilitating dynamic measurements of response to oxygen intervention. Altering the inhaled gas to oxygen produced a significant increase in mean pO(2) from 55 Torr to 238 Torr in thigh muscle and a smaller, but significant, increase in mean pO(2) from 17 Torr to 78 Torr in MAT-Lu tumors. Thus, PISTOL enabled mapping of tissue pO(2) at multiple locations and dynamic changes in pO(2) in response to intervention. This new method offers a potentially valuable new tool to image pO(2) in vivo for any healthy or diseased state by (1)H MRI. PMID:18574806

  1. Polydimethyl siloxane wet etching for three dimensional fabrication of microneedle array and high-aspect-ratio micropillars

    PubMed Central

    Deng, Yu-Luen; Juang, Yi-Je

    2014-01-01

    Among various transdermal drug delivery (TDD) approaches, utilizing the microneedles (MNs) not only can penetrate the skin but also deliver the drug with reduced tissue damage, reduced pain, and no bleeding. However, the MNs with larger height are required to overcome the skin barrier for effective TDD. Unlike 2D patterning, etching polydimethyl siloxane (PDMS) micropillars for fabrication of 3D microstructures is presented. The PDMS micropillars were first constructed by casting PDMS on the computer numerical control-machined cylindrical microwells, which then went through etching process to obtain the MNs for subsequent fabrication of polymer MNs or high aspect ratio micropillars. PMID:24803970

  2. Polydimethyl siloxane wet etching for three dimensional fabrication of microneedle array and high-aspect-ratio micropillars.

    PubMed

    Deng, Yu-Luen; Juang, Yi-Je

    2014-03-01

    Among various transdermal drug delivery (TDD) approaches, utilizing the microneedles (MNs) not only can penetrate the skin but also deliver the drug with reduced tissue damage, reduced pain, and no bleeding. However, the MNs with larger height are required to overcome the skin barrier for effective TDD. Unlike 2D patterning, etching polydimethyl siloxane (PDMS) micropillars for fabrication of 3D microstructures is presented. The PDMS micropillars were first constructed by casting PDMS on the computer numerical control-machined cylindrical microwells, which then went through etching process to obtain the MNs for subsequent fabrication of polymer MNs or high aspect ratio micropillars. PMID:24803970

  3. Neuro-impressions: interpreting the nature of human creativity

    PubMed Central

    Siler, Todd Lael

    2012-01-01

    Understanding the creative process is essential for realizing human potential. Over the past four decades, the author has explored this subject through his brain-inspired drawings, paintings, symbolic sculptures, and experimental art installations that present myriad impressions of human creativity. These impressionistic artworks interpret rather than illustrate the complexities of the creative process. They draw insights from empirical studies that correlate how human beings create, learn, remember, innovate, and communicate. In addition to offering fresh aesthetic experiences, this metaphorical art raises fundamental questions concerning the deep connections between the brain and its creations. The author describes his artworks as embodiments of everyday observations about the neuropsychology of creativity, and its all-purpose applications for stimulating and accelerating innovation. PMID:23091455

  4. Dental CAD/CAM technologies: the optical impression (II).

    PubMed

    Pfeiffer, J

    1999-01-01

    This article, has explained the principles and characteristics of the optical impression, such as is used in the Cerec dental CAD/CAM system, and discussed the limitations and perspectives for future developments of the technique. Optical methods of measurement are clearly capable of satisfying the basic requirements of a direct CAD/CAM procedure for fabricating restorations for individual teeth. Further improvements in the technique beyond the level that Cerec 2 offers today are conceivable but still in the far future because they require significant improvements of the basic components. These developments can be expected to enhance the accuracy of measurement and ease of operation, as well as permitting the measurement of several teeth at once for the fabrication of fixed partial dentures. PMID:11351452

  5. Plant-Wide Energy Conservation Program Yields Impressive Results

    E-print Network

    Adlkes, R. P.; Zupko, A. J.; Adams, J. W.

    1980-01-01

    ,775 458,411 21.6? 1976 49,837 391,900 441,737 24.4 1977(1) 53,944 317,570 371,514 36.5 1978(2) 57,512 222,430 279,942 52.1 1979(2) 61,571 143,515 205,086 64.9 1980(3) 68,240 134,030 202,270 65.4 (1) Summer boiler shut-down initiated in 1977. (2..."PLANT-WIDE ENERGY CONSERVATION PROGRAM YIELDS IMPRESSIVE RESULTS" Robert P. Adlkes Alan J. Zupko, P.E. Joseph W. Adams Teledyne Continental Motors Roy F. Weston, Inc. Bettcher Manufacturing Corp. Muskegon, Michigan West Chester, Pennsylvania...

  6. The complex interplay between semantics and grammar in impression formation.

    PubMed

    Shreves, Wyley B; Hart, William; Adams, John M; Guadagno, Rosanna E; Eno, Cassie A

    2014-09-01

    We sought to bridge findings showing that (a) describing a person's behavior with the perfective verb aspect (did), compared to the imperfective aspect (was doing), increases processing of semantic knowledge unrelated to the target's action such as stereotypes and (b) an increased recognition of stereotypical thoughts often promotes a judgment correction for the stereotypes. We hypothesized an interplay between grammar (verb conjugation) and semantic information (gender) in impression-formation. Participants read a resume, attributed to a male or female, for a traditionally masculine job. When the resume was written in the imperfective, people rated a male (vs. female) more positively. When the resume was in the perfective, this pattern reversed. Only these latter effects of gender were influenced by cognitive load. Further, people more quickly indicated the applicant's gender in the perfective condition, suggesting an enhanced focus on gender during processing. PMID:24950389

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  8. Production of a calcium silicate cement material from alginate impression material.

    PubMed

    Washizawa, Norimasa; Narusawa, Hideaki; Tamaki, Yukimichi; Miyazaki, Takashi

    2012-01-01

    The purpose of this study was to synthesize biomaterials from daily dental waste. Since alginate impression material contains silica and calcium salts, we aimed to synthesize calcium silicate cement from alginate impression material. Gypsum-based investment material was also investigated as control. X-ray diffraction analyses revealed that although firing the set gypsum-based and modified investment materials at 1,200°C produced calcium silicates, firing the set alginate impression material did not. However, we succeeded when firing the set blend of pre-fired set alginate impression material and gypsum at 1,200°C. SEM observations of the powder revealed that the featured porous structures of diatomite as an alginate impression material component appeared useful for synthesizing calcium silicates. Experimentally fabricated calcium silicate powder was successfully mixed with phosphoric acid solution and set by depositing the brushite. Therefore, we conclude that the production of calcium silicate cement material is possible from waste alginate impression material. PMID:22864217

  9. Managing and creating an image in the interview: the role of interviewee initial impressions.

    PubMed

    Swider, Brian W; Barrick, Murray R; Harris, T Brad; Stoverink, Adam C

    2011-11-01

    In employment interviews, individuals use impression management tactics to present themselves as suitable candidates to interviewers. However, not all impression management tactics, or the interviewees who employ them, are effective at positively influencing interview scores. Results of this study indicate that the relationship between impression management tactic usage and interview success is contingent on the type of tactic employed. Specifically, self-promotion was found to have a positive relationship (r = .20) and slight (r = -.11) and extensive (r = -.19) image creation were found to have negative relationships with end-of-interview scores. Further, the relationships between these 3 impression management tactics were moderated by interviewees' initial impressions of the interview (?R² ranged from .04 to .10). Interviewees who perceived they were seen as less suitable during rapport building were more effective when using any of the 3 impression management tactics. PMID:21639599

  10. Copper electroplating of non-aqueous elastomeric impression materials: a subjective appraisal of their platability.

    PubMed

    Payne, J A; Jeganathan, S

    1994-01-01

    Electroplating of non-aqueous elastomeric impression materials is a well-documented technique. Electroplated silver or copper plated dies have many clinical advantages compared to other die systems. Silver electroplating appears to be used more frequently than copper electroplating. Utilization of silver for electroplating requires an appreciation of financial and biohazard considerations. Research on compatibility of copper electroplating with current non aqueous elastomeric impression materials is lacking. Samples of currently used non aqueous elastomeric impression materials were used to register impressions of conventional crown preparations on a typodont. These impressions were electroplated to form copper plated dies. The surface qualities of the dies were evaluated. Not all impression materials produced visually acceptable or workable copper plated dies. PMID:9582678

  11. Interpretation of Appearance: The Effect of Facial Features on First Impressions and Personality

    PubMed Central

    Wolffhechel, Karin; Fagertun, Jens; Jacobsen, Ulrik Plesner; Majewski, Wiktor; Hemmingsen, Astrid Sofie; Larsen, Catrine Lohmann; Lorentzen, Sofie Katrine; Jarmer, Hanne

    2014-01-01

    Appearance is known to influence social interactions, which in turn could potentially influence personality development. In this study we focus on discovering the relationship between self-reported personality traits, first impressions and facial characteristics. The results reveal that several personality traits can be read above chance from a face, and that facial features influence first impressions. Despite the former, our prediction model fails to reliably infer personality traits from either facial features or first impressions. First impressions, however, could be inferred more reliably from facial features. We have generated artificial, extreme faces visualising the characteristics having an effect on first impressions for several traits. Conclusively, we find a relationship between first impressions, some personality traits and facial features and consolidate that people on average assess a given face in a highly similar manner. PMID:25233221

  12. Crosslinkable poly(vinyl acetate) emulsions for wood adhesive

    Microsoft Academic Search

    Jia Lu; Allan J. Easteal; Neil R. Edmonds

    2011-01-01

    Purpose – The purpose of this paper is to enhance the water resistance and the heat resistance of poly(vinyl acetate) (PVAc) emulsion adhesive, by providing the emulsion with controllable thermosetting capability. Design\\/methodology\\/approach – Emulsion polymerisation was used to synthesise PVAc\\/VeoVa 10 copolymers with varying proportions of acetoacetoxyethyl methacrylate (AAEM) incorporated in the copolymer chains. The AAEM component provided sites for

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

    Microsoft Academic Search

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

    2011-01-01

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

  14. Immobilization of lipase enzyme in polyvinyl alcohol (PVA) nanofibrous membranes

    Microsoft Academic Search

    Y. Wang; Y.-L. Hsieh

    2008-01-01

    Lipase enzyme from Candida rugosa (E.C. 3.1.1.3) has been successfully immobolized in 100–500nm diameter fibers via electrospinning of aqueous mixtures of lipase and polyvinyl alcohol (PVA). Enzyme loading in these bicomponent fibers reached as high as 50%. The catalytic activity of the fiber bound lipase was the same as the crude enzyme, showing no adverse effects from either electric charges

  15. Study on morphology of electrospun poly(vinyl alcohol) mats

    Microsoft Academic Search

    Chunxue Zhang; Xiaoyan Yuan; Lili Wu; Yue Han; Jing Sheng

    2005-01-01

    Submicron poly(vinyl alcohol) (PVA) fiber mats were prepared by electrospinning of aqueous PVA solutions in 6–8% concentration. Fiber morphology was observed under a scanning electron microscope and effects of instrument parameters including electric voltage, tip–target distance, flow rate and solution parameters such as concentration on the morphology of electrospun PVA fibers were evaluated. Results showed that, when PVA with higher

  16. Water resistance of photocrosslinked polyvinyl alcohol based fibers

    Microsoft Academic Search

    Yurong Liu; Brian Bolger; Paul A. Cahill; Garrett B. McGuinness

    2009-01-01

    Electrospinning and photocrosslinking were combined in this study to prepare water-insoluble fibers of polyvinyl alcohol (PVA) with the styrylpyridinium (SbQ) pendent group. The PVA-SbQ exhibited high photosensitivity in a spectroscopic study. Electrospun PVA and PVA-SbQ fibers were soluble and totally dissolved after water immersion. UV irradiation of the electrospun mat led to a significant decrease in the mass loss of

  17. Fabrication and characterization of conducting polyvinyl alcohol nanofibers

    Microsoft Academic Search

    Daehwan Cho; Nikolas Hoepker; Margaret W. Frey

    Conducting polyvinyl alcohol (PVA) nanofibers with diameters ranging from 100nm to 300nm were fabricated by an electrospinning method from spinning dopes of the dissolved PVA polymer in aqueous dispersion of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). Using a chemical cross-linking agent, glutaraldehyde (GA), water insoluble conducting PVA nanofibers were obtained through an in-situ crosslinking of PVA polymer during electrospinning. The cross-linked conducting nanofibers

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

    Microsoft Academic Search

    Jue Lu; Tao Wang; Lawrence T. Drzal

    2008-01-01

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

  19. Epoxidation of thermally degraded poly(vinyl chloride)

    Microsoft Academic Search

    Tibor Szakács; Béla Iván

    2004-01-01

    Epoxidation of conjugated polyenes formed by thermal degradation of poly(vinyl chloride) (PVC) was carried out in cyclohexanone and tetrahydrofuran solution with m-chloroperoxybenzoic acid (mCPBA). PVC was thermally degraded in the solid state under continuous nitrogen flow at 200 °C for 30 min leading to 0.6 mol% double bonds in the polymer chain as determined from the UV-visible spectrum of the

  20. Cross-linked polyvinyl alcohol films as alkaline battery separators

    Microsoft Academic Search

    Dean W. Sheibley; O. D. Gonzalez-Sanabria; M. A. Manzo

    1983-01-01

    Cross-linking methods have been investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: PVA-dialdehyde blends post-treated with an acid or acid periodate solution and PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality. Laboratory samples

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

    Microsoft Academic Search

    L. Hsu; W. H. Philipp; D. W. Sheibley

    1981-01-01

    A film-forming polyvinyl alcohol polymer is mixed with a polyaldehyde-polysaccharide cross-linking agent having at least two monosaccharide units and a plurality of aldehyde groups per molecule, preferably an average of at least one aldehyde group per monosaccharide units. The cross-linking agent, such as a polydialdehyde starch, is used in an amount of about 2.5 to 20% of the theoretical amount

  2. Humidity sensors using polyvinyl alcohol mixed with electrolytes

    Microsoft Academic Search

    Mu-Rong Yang; Ko-Shao Chen

    1998-01-01

    Resistive-type humidity sensors were fabricated by casting polyvinyl alcohol on comb-shaped electrodes. The impedance of the PVA film decreased with increasing relative humidity (RH), the best sensing behavior being attained at a film thickness of 10 ?m. The addition of p-styrenesulfonate sodium (PSSD), sodium chloride or m-benzenedisulfonate disodium (MBSD) to the PVA film was effective for improving the humidity sensitivity.

  3. Adsorptive Selectivity of DNA\\/Polyvinyl Alcohol Interpenetrating Polymer Networks

    Microsoft Academic Search

    XiangDong Liu; Tetsuro Kubo; WenXing Chen; Jonganurakkun Benjamas; Tomomi Yonemichi; Norio Nishi

    2011-01-01

    An interpenetrating polymer network (IPN) containing natural DNA was prepared by cross-linking polyvinyl alcohol (PVA) with a glutaraldehyde (GA) reagent and then cross-linking DNA with UV irradiation. This DNA\\/PVA IPN structure could selectively bind chemicals with affinity for DNA, and adsorb L-tryptophan (L-Trp) with a high chiral-selectivity over D-Trp. More than ten times more L-Trp was adsorbed on the DNA\\/PVA

  4. Cross-linked polyvinyl alcohol films as alkaline battery separators

    Microsoft Academic Search

    D. W. Sheibley; M. A. Manzo; O. D. Gonzalez-Sanabria

    1982-01-01

    Cross-linking methods were investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: (1) PVA-dialdehyde blends post-treated with an acid or acid periodate solution (two-step method) and (2) PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid

  5. A Novel Technique of Impression Procedure in a Hemimaxillectomy Patient with Microstomia

    PubMed Central

    Deogade, Suryakant C.

    2012-01-01

    A restricted mouth opening in hemimaxillectomy patient can create a significant problem with the insertion and the removal of the obturator prosthesis. Even it poses a problem in impression making due to small oral opening. A modification of the standard impression procedure is often necessary to accomplish an acceptable impression in the fabrication of a successful prosthesis. Sectional trays are a good option for such patients. This paper describes a novel technique of impression procedure and a method of fabricating a sectional tray with the anterior and the posterior locking mechanism for a hemimaxillectomy patient with limited oral opening. PMID:23316395

  6. Formation of Linear Polyenes in Thermal Dehydration of Polyvinyl Alcohol, Catalyzed by Phosphotungstic Acid

    NASA Astrophysics Data System (ADS)

    Tretinnikov, O. N.; Sushko, N. I.

    2015-01-01

    In order to obtain linear polyenes in polyvinyl alcohol films via acid-catalyzed thermal dehydration of the polyvinyl alcohol, we used phosphotungstic acid as the catalyst: a safe and heat-stable solid chemical compound. We established that phosphotungstic acid, introduced as solid nanoparticles into polyvinyl alcohol films, is a more effective dehydration catalyst than hydrochloric acid, since in contrast to HCl it does not evaporate from the film during heat treatment.

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

    Microsoft Academic Search

    W. H. Philipp; L. C. Hsu; D. W. Sheibley

    1979-01-01

    A battery separator was produced from a polyvinyl alcohol sheet structure which was subjected to an in situ, self crosslinking process by selective oxidation of the 1,2 diol units present in the polyvinyl alcohol sheet structure. The 1,2 diol units were cleaved to form aldehyde end groups which subsequently crosslink through acetalization of the 1,3 diol units of the polyvinyl

  8. Absorption of a linear (L2) and a cyclic (D4) siloxane using different oils: application to biogas treatment.

    PubMed

    Rojas Devia, Carolina; Subrenat, Albert

    2013-01-01

    Hydrophobic volatile methyl siloxanes (VMS), such as hexamethyldisiloxane (L2) and octamethylcyclotetrasiloxane (D4), present a low solubility in water. An alternative treatment by absorption into hydrophobic absorbents was therefore studied. For this purpose, three different absorbents, motor oil, cutting oil and a water-cutting oil mixture, were selected with the aim of re-using a waste product. The set of experiments was carried out in a bubble column, where parameters such as inlet concentration, residence time and temperature were studied. The best performance for the removal of both siloxanes, in terms of absorption capacity, was observed for motor oil, particularly for D4. In fact, motor oil removal efficiency for D 4 was 80%, whereas for L2 it was 60%, indicating that D 4 is more easily absorbed than L2. In the case of water-cutting oil, this showed a mass transfer enhancement from the gas phase to the liquid phase compared with water alone. Furthermore, a removal efficiency of 70% was observed for D 4, showing that the addition of an oil fraction to a water system improves the absorption of VMS. These results show that VMS absorption into oils could be a promising way to achieve their abatement. PMID:24617070

  9. Holographic polymer dispersed liquid crystal system utilizing the co-polymerizations with siloxane compounds and polypropylene glycol derivatives

    NASA Astrophysics Data System (ADS)

    Takanokura, Tomoe; Kurashige, Makio; Ishida, Kazutoshi; Ohyagi, Yasuyuki; Watanabe, Masachika; Cho, Yeong Hee

    2011-03-01

    Holographic polymer dispersed liquid crystal (HPDLC) has a feature that can control diffraction of light by applying electric field. HPDLC can be used for optical elements such as an optical switch, or a polarized beam splitter etc. One of the reactive systems for making HPDLC is well known photopolymerization-induced phase separation (PIPS). The performance of HPDLC by PIPS is dependent on distribution of oriented liquid crystal (LC) molecules, or size and shape of LC droplets. These are controlled by chemical structure or functional group of polymer matrix. In this report, Organic-inorganic hybrid materials having sensitivity at 532 nm were synthesized. Polymer matrix was formed with co-polymerization of siloxane-containing materials and poly (propylene glycol) derivatives functionalized with methacrylate groups. Siloxane chain was introduced in polymer matrix to encourage phase separation of LC and stabilize grating structure. In addition, poly (propylene glycol) derivatives were designed to control polymerization rate and extent of phase separation of LC. The characterization of HPDLC was evaluated in terms of diffraction efficiency, contrast between diffraction and transparency modes by applying voltage, and switch speed. As a result, the separation ratio of p-polarized light and s-polarized light was 100:1. The value of ?n was 0.075, and the index matching of both polymer-rich layer and LC-rich layer was completed at voltage of 17V/?m.

  10. Grafting of a reactive siloxane onto an alpha-olefin in the melt phase

    NASA Astrophysics Data System (ADS)

    Bekele, Solomon

    1999-11-01

    This dissertation presents the outcomes of a study undertaken to graft a reactive siloxane onto an alpha-olefin in the melt phase with the objective of conducting grafting and sequentially making a film of low coefficient of friction in a twin screw extruder. The areas of focus of the research were (1) design of experiments, (2) batch kinetic study, (3) twin screw extruder grafting and film making and (4) film property analysis. The primary materials of the study were a film grade homopolymer polyethylene, Equistar NA345-013, a vinylmethylsiloxane-dimethylsiloxane copolymer, Gelest VDT-731, and an ethyl 3,3-di-(t-amylperoxy)-butyrate, Elf Atochem Lupersol 533-M75. The batch mixer was a Haake rheomixRTM 400 modified to conduct reaction under a N2 blanket. Continuous reactive extrusion and sequential film making was done in a Leistritz 18mm x 40/1 L/D corotating and intermeshing twin screw extruder coupled with a flex lip die. Reaction samples were analyzed using FT-IR for degree of grafting and GPC to determine changes in molecular weight distribution as measures of degree of side reactions. The factors with main effects on degree of grafting were found to be mole percent vinyl functionality available for reaction, amount of initiator and mixing temperature. Among side reactions chain scission was found to be absent. The degree of cross-linking was mainly dependent on mole percent of free radical initiator and mixing temperature. Grafting was found to be a third order reaction with respect to vinylsiloxane concentration. Batch kinetic data were scaled up to continuous reactive extrusion in the twin screw extruder. Tracer experiments with TiO2 were used to estimate the average residence time and the extent of axial dispersion. An axial plug flow dispersion model was assumed to represent the nonideal flow of the grafting reaction in the twin screw extruder. The model was found to under predict the degree of grafting from 9% up to 25%. The coefficient of friction of the grafted film was found to be lower than the base polymer film by 50% to 60%. This increased to 65% to 75% when both sets of film samples were subjected to 50 kGy of electron beam irradiation.

  11. How Do You Say `Hello'? Personality Impressions from Brief Novel Voices

    E-print Network

    Todorov, Alex

    How Do You Say `Hello'? Personality Impressions from Brief Novel Voices Phil McAleer1 *, Alexander experiment, 320 participants rated 64 sub-second vocal utterances of the word `hello' on one of 10. Citation: McAleer P, Todorov A, Belin P (2014) How Do You Say `Hello'? Personality Impressions from Brief

  12. The Rheology of Liquids: A Comparison of Clinicians’ Subjective Impressions and Objective Measurement

    Microsoft Academic Search

    Catriona M. Steele; Pascal H. H. M. Van Lieshout; Douglas H. Goff

    2003-01-01

    Texture-modified diets are commonly prescribed for patients with dysphagia; it is therefore important to demonstrate that clinicians form accurate impressions of the rheological (flow) properties of the items that they recommend for their clients. We explored the correlation between objective rheological measurement and clinicians’ subjective impressions of liquid consistency, rated on the bases of product labeling and sampling. Ten liquids,

  13. A New Generation of Sterile and Radiopaque Impression Materials—an in vitro Cytotoxicity Study

    Microsoft Academic Search

    Chiara Coppi; Chiara Paolinelli Devincenzi; Sergio Bortolini; Ugo Consolo; Roberta Tiozzo

    2007-01-01

    Impression materials are largely used to record the geometry of dental tissue. Hence, the assessment of their possible cytotoxicity is a necessary step in the evaluation of their biocompatibility. The present study is carried out to evaluate the cytotoxicity of a new elastomeric sterile and radiopaque impression material. Human gingival fibroblasts, cultured in vitro are exposed directly to Elite Implant

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

    ERIC Educational Resources Information Center

    Larson, Jeff A.; Tsitsos, William

    2013-01-01

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

  15. [Effects of fundamental frequency and speech rate on impression formation].

    PubMed

    Uchida, Teruhisa; Nakaune, Naoko

    2004-12-01

    This study investigated the systematic relationship between nonverbal features of speech and personality trait ratings of the speaker. In Study 1, fundamental frequency (F0) in original speech was converted into five levels from 64% to 156.25%. Then 132 undergraduates rated each of the converted speeches in terms of personality traits. In Study 2 134 undergraduates similarly rated the speech stimuli, which had five speech rate levels as well as two F0 levels. Results showed that listener ratings along Big Five dimensions were mostly independent. Each dimension had a slightly different change profile over the five levels of F0 and speech rate. A quadratic regression equation provided a good approximation for each rating as a function of F0 or speech rate. The quadratic regression equations put together would provide us with a rough estimate of personality trait impression as a function of prosodic features. The functional relationship among F0, speech rate, and trait ratings was shown as a curved surface in the three-dimensional space. PMID:15747562

  16. Personality and workplace impression management: Correlates and implications.

    PubMed

    Bourdage, Joshua S; Wiltshire, Jocelyn; Lee, Kibeom

    2015-03-01

    In the present study, we investigated the role of personality in understanding impression management (IM) behaviors. We hypothesized that the HEXACO model of personality could provide an intricate understanding of the dispositional bases of IM behaviors, as well as coworkers' ability to accurately perceive the IM of those they work with. Using 2 samples (N = 176 and N = 366), we found that the common core underlying 5 IM behaviors possesses a strong negative relationship with the personality trait of Honesty-Humility, such that individuals low in this trait were more likely to report using all IM behaviors. Furthermore, we found that the unique variance associated with specific IM behaviors can be understood using other traits included in the HEXACO personality model, including Emotionality, Extraversion, Agreeableness, and Conscientiousness. In a subset of the data (N = 100), we examined self-coworker convergence in IM and personality. We found that while coworkers are adequate at judging traditional personality traits, the self-coworker convergence for all 5 IM behaviors, as well as the personality trait of Honesty-Humility, were not significant. This adds to a growing body of evidence that coworkers may not be good at accurately perceiving IM or Honesty-Humility in the workplace. (PsycINFO Database Record (c) 2015 APA, all rights reserved). PMID:25243995

  17. On the role of emotional traits in impression formation.

    PubMed

    Nigro, G; Matarazzo, O

    1994-10-01

    280 Italian undergraduates (90 men and 190 women), ages 18 to 30 years, rated a warm, cold, jealous, or envious stimulus person on 15 7-point semantic differential scales. Varying the sex of the stimulus person, 8 different versions of the description were obtained. Factor analysis, carried out to identify a smaller set of non-redundant dimensions, yielded three factors. A multivariate analysis of variance, 4 (warm, cold, jealous, envious) x 2 (male stimulus person, female stimulus person) x 2 (male respondents, female respondents), indicated significant effects for the variable "trait" on the first and second factors, an interaction between the sex of the stimulus person and the sex of the respondent on the first factor, and an effect for the sex of the respondent on the second factor. The traits "envious" and "jealous" acted as central qualities, and the sex of the stimulus person and of the respondent played an important role in impression formation. Further implications of the finding were discussed. PMID:7870499

  18. How shadows shape our impression of rough surfaces

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed

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

    2015-03-01

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

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

    PubMed Central

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

    2014-01-01

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

  1. Surface porosity of stone casts resulting from immersion of addition silicone rubber impressions in disinfectant solutions.

    PubMed

    Hiraguchi, Hisako; Kaketani, Masahiro; Hirose, Hideharu; Kikuchi, Hisaji; Yoneyama, Takayuki

    2014-01-01

    This study investigated the effects of immersion of addition silicone rubber impressions in disinfectant solutions on the surface porosity of the resulting stone casts. Five brands of type 2 and 3 addition silicone rubber impression materials and one brand of type 4 dental stone were used. Impressions of a master die designed to simulate an abutment tooth were immersed in disinfectant for 30 minutes. The disinfectants used were 2% glutaraldehyde solution and 0.55% ortho-phthalaldehyde solution. The surface porosities of stone casts obtained from two brands of impression materials immersed in disinfectant for 30 minutes were determined. Results suggest that impression materials immersed in disinfectant solutions need sufficient time before pouring into dental stone. PMID:25390872

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  3. Continuous microcellular foaming of polyvinyl chloride and compatibilization of polyvinyl chloride and polylactide composites

    NASA Astrophysics Data System (ADS)

    Shah, Bhavesh

    This dissertation focuses on overcoming existing limitations of WPCs which prevent them from realizing their full market potential. These limitations include: (i) lack of a continuous extrusion process for microcellular foaming of polyvinyl chloride (PVC) and its composites using supercritical fluids to reduce the high density of the WPCs, (ii) need for an efficient coupling agent for WPCs to overcome the poor compatibility between wood and plastic, and (iii) unproven use of wood as a filler for the biopolymer polylactide (PLA) to make "green" composites. These limitations were addressed through experimentation to develop a continuous extrusion process for microcellular foaming, and through surface modification of wood flour using natural coupling agents. The effects of wood flour, acrylic modifier and plasticizer content on the rheological properties of PVC based WPCs were studied using an extrusion capillary rheometer and a two-level factorial design. Wood flour content and acrylic modifier content were the major factors affecting the die swell ratio. Addition of plasticizer decreased the true viscosity of unfilled and filled PVC, irrespective of the acrylic modifier content. However, the addition of acrylic modifier significantly increased the viscosity of unfilled PVC but decreased the composite viscosity. Results of the rheological study were used to set baseline conditions for the continuous extrusion foaming of PVC WPCs using supercritical CO 2. Effects of material composition and processing conditions on the morphology of foamed samples were investigated. Foamed samples were produced using various material compositions and processing conditions, but steady-state conditions could not be obtained for PVC. Thus the relationships could not be determined. Incompatibility between wood flour and PVC was the focus of another study. The natural polymers chitin and chitosan were used as novel coupling agents to improve interfacial adhesion between the polymer matrix and wood fiber. Results indicated that addition of chitin and chitosan significantly increased the flexural properties and storage modulus of PVC WPCs, compared to composites without coupling agent. Significant improvements were attained with 0.5 wt. % chitosan and with 6.67 wt. % chitin. Based on the efficiency of chitosan as a coupling agent for PVC based WPCs, a biodegradable composite using polylactide (PLA) and chitosan was developed. Wood flour (0--40 wt. %) was evaluated as a filler for PLA composites and its effect on mechanical, thermal and chemical properties was studied with and without chitosan (0--10 wt. %). Addition of wood flour significantly increased the flexural and storage moduli of PLA-wood flour composites, but had no effect on glass transition temperature (Tg). Chitosan had no significant effect on any of the properties of the composites studied. Development of an efficient and effective coupling agent for PVC wood composite is a significant development which will increase performance while reducing cost. Wood filled PLA composites can further expand WPCs into applications such as packaging and automotive. Results from these studies have broadened the current knowledge base for WPC products and will be useful in the continued expansion of wood composites technology into a variety of industries.

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

    SciTech Connect

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  6. Cross-linked polyvinyl chloride resin foam and method of manufacturing the same

    Microsoft Academic Search

    J. Sasajima; K. Mogi; H. Nagai; A. Nojiri; N. Shiina

    1984-01-01

    This invention provides a method of continuously manufacturing a cross-linked polyvinyl chloride resin foam sheet which has a low density, uniformly fine cell, excellent thermal moldability and high heat resistance and is neither deformed nor deteriorated even by long storage characterized by uniformly kneading the polyvinyl chloride resin with a blowing agent, stabilizer, plasticizer and cross-linking promoter without causing the

  7. Polymeric sulfides CdS, CuS, and NiS in polyvinyl alcohol matrix

    NASA Astrophysics Data System (ADS)

    Prosanov, I. Yu.; Bulina, N. V.

    2014-06-01

    Cadmium, copper, and nickel sulfides have been synthesized in a polyvinyl alcohol matrix. The specimens have been investigated by means of vibration spectroscopy and X-ray diffraction analysis. The obtained data have confirmed the formation of cadmium sulfide with a polymeric chain structure in polyvinyl alcohol. The possibility of producing similar materials based on copper and nickel sulfides has been discussed.

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

    Microsoft Academic Search

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

    2011-01-01

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

  9. Microwave reflectivity measurement of silicon urea polyvinyl alcohol \\/ epoxy resin composites in X and Ku bands

    Microsoft Academic Search

    M. Murugan; V. K. Kokate

    2009-01-01

    In the paper presented here, a thermally stable epoxy resin modified urea - polyvinyl alcohol - silicon blends have been prepared by in situ polymerization technique. For this, the materials were modified with triethylene tetramine (hardener) to obtain highly cross-linked thermosetting resins. The authors have synthesized the polymer composites; silicon-urea-polyvinyl alcohol in three ratios in weight percentages with analytical reagent

  10. Sorption of boric acid by hydroxylic sorbents synthesized from polyvinyl alcohol and polyvinylene glycol

    Microsoft Academic Search

    G. V. Kiselgof; L. K. Arkhangelskii; N. A. Bochkova

    1986-01-01

    It has been shown that sorbents synthesized from polyvinyl alcohol (PVA) and polyvinyl glycol (PVG) are the most effective agents for extraction of boron from natural waters and brines. The action of such sorbents is based on the ability of boric acid to form stable complexes with polyhydroxy compounds. In this work the authors studied hydroxylic sorbents differing in OH-group

  11. Solute Diffusion in Poly(vinyl alcohol)/Poly(acrylic acid) Interpenetrating Networks

    E-print Network

    Peppas, Nicholas A.

    Solute Diffusion in Poly(vinyl alcohol)/Poly(acrylic acid) Interpenetrating Networks Nikolaos A contained within the hydrogel at equilibrium; it is a function of the network structure, cross-linking ratio studied such interactions using well- characterized interpenetrating networks of poly(vinyl alcohol) (PVA

  12. The First Impression of Data Sent by Two Martian Rovers

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    ``Spirit'' at the Gusev crater near the dichotomy boundary sent a panoramic view, an image of the near ground and a very close view of a small spot analyzed by X-ray. The first impression of chaotic disposition of big and small rocks and sandy fragments is wrong. All scales images display striations in 4 directions probably due to intersecting undulations, besides, rock fragments are rather evenly distributed. This is not of surprise because many MOLA images show very regular patterns described earlier for intersecting wave processes on planetary surfaces [1]. The middle scale image shows angular rock fragments of various sizes protruding soil. There is an impression that the protruding blocks represent uplifted parts of a wave-woven surface of volcanic infilling , subsided parts being covered with sandy soil mainly of eolian origin. Such an interpretation is supported by the THEMIS image (released 23 Sept., 2003 in Internet) of a 22 km-diameter crater on Sirenum Fossae where wave structurized (volcanic?) material is gradually covered by eolian sediments leaving protruding high standing blocks (antinodes). The soil X-ray analysis shows high Si an Fe, some Al, Ca, Mg, K, Na, Cl, S, minor Cu, Ni, Zn that should be expected for a mixed material at low/highland contact contaminated by an eolian stuff. ``Opportunity'' is the first highland landing and in this is its highest importance. It seems that long awaited light (in color and density) rock type without Fe [2, 3 & others] is in front of us. The leveled out white outcrops probably represent this kind of rocks (albitites, syenites). Eleveted K, Na, CL, S, Si and H20 (!) detected by gamma and neutron spectra can be explained by sodalite (hydrosodalite) and cancrinite group minerals present in nepheline syenites -- albitites and always accompanied by zeolites containing water. The high chemical dichotomy (and mantle fractionation) between lowlands and highlands is an important part of the wave planetology (Theorem 4 [3]). References: [1] Kochemasov G.G. (1991) Periodic system of multi-ring planetary structures as result of interference of variously oriented lithospheric waves // Astronom. Tsirkular RAS, # 1550, 35-36 (in Russian); [2] Kochemasov G.G. (1995) Possibility of highly contrasting rock types at martian highland/lowland contact // In: Golombek M.P., Edgett K.S., and Rice J.W.Jr., eds. Mars Pathfinder Landing Site Workshop II: Characteristics of the Ares Vallis Region and Field Trips to the Channeled Scabland, Washington. LPI Tech. Rpt. 95-01, Pt. 1, LPI, Houston, 63 pp.; [3] Kochemasov G.G. (1999) On a successful prediction of martian crust fractionation based on comparative wave planetology // The Fifth International Conference on Mars, July 18-23, 1999, Pasadena, California, Abstr. # 6034, (CD-ROM).

  13. Appearance-based first impressions and person memory.

    PubMed

    Bell, Raoul; Mieth, Laura; Buchner, Axel

    2015-03-01

    Previous research has demonstrated that people preferentially remember reputational information that is emotionally incongruent to their expectations, but it has left open the question of the generality of this effect. Three conflicting hypotheses were proposed: (a) The effect is restricted to information relevant to reciprocal social exchange. (b) The effect is most pronounced for emotional (approach-and-avoidance-relevant) information. (c) The effect is due to a general tendency of the cognitive system to attend to unexpected and novel information regardless of its (emotional) content. Here, we varied the type of to-be-remembered person information across experiments. To stimulate expectations, we selected faces whose facial appearance was rated as pleasant or disgusting (Experiments 1 and 2), as intelligent or unintelligent (Experiment 3), or as being that of a lawyer or a farmer (Experiment 4). These faces were paired with behavior descriptions that violated or confirmed these appearance-based 1st impressions. Source memory for the association between the faces and the descriptions was assessed with surprise memory tests. The results show that people are willing to form various social expectations based on facial appearance alone, and they support the hypothesis that the classification of the faces in the memory test is biased by schema-congruent guessing. Source memory was generally enhanced for information violating appearance-based social expectations. In sum, the results show that person memory is consistently affected by different kinds of social expectations, supporting the idea that the mechanisms determining memory performance generalize beyond exchange-relevant reputational and emotional information. (PsycINFO Database Record (c) 2015 APA, all rights reserved). PMID:24999709

  14. The quality of impressions for crowns and bridges: an assessment of the work received at three commercial dental laboratories. assessing qualities of impressions that may lead to occlusal discrepancies with indirect restorations.

    PubMed

    Storey, D; Coward, T J

    2014-03-01

    There are few published studies that directly assess the quality of impressions for crowns and bridges in the UK. This paper considers aspects of impression quality with particular attention to factors causing potential occlusal discrepancies in the final restoration. To this end three dental laboratories were visited over a 3-month period. All impressions for conventional crown and bridgework that arrived on the days of the visits were examined and assessed against criteria defined on a custom-designed assessment form. A total of 206 impression cases were considered in this study. Flexible impression trays were used for 65% of working impressions. Their use was more common for NHS work than for private work. 31.9% of all alginate impressions examined were not adequately fixed to the tray. Visible contamination of impressions was not uncommon. PMID:24922994

  15. Preparation and application of low molecular weight poly(vinyl chloride). III mechanical properties of blended poly(vinyl chloride)

    SciTech Connect

    Yamamoto, Kikuo; Maehala, Takashi; Mitani, Katsuo; Mizutani, Yukio (Tokuyama Soda Co., Ltd., Tokuyama-city (Japan))

    1993-11-05

    The blending effect of poly(vinyl chloride) with relatively higher molecular weight (HMW-PVC) and relatively lower molecular weight (LMW-PVC) has been investigated by measuring various mechanical properties: melt properties, tensile strength, tensile modulus, and impact strength. The blended PVC has slightly improved melt properties in comparison with the HMW-PVC used. The tensile strength of the blended PVC is related to the weight-average polymerization degree (Pw) of LMW-PVC and the LMW-PVC content. At the LMW-PVC content of 20%, the tensile strength of blended PVC is a maximum: approximately 58 MPa.

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

    PubMed

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

    2014-01-21

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

  17. High-resolution calorimetric study of a liquid crystalline organo-siloxane tetrapode with a biaxial nematic phase.

    PubMed

    Cordoyiannis, George; Apreutesei, Daniela; Mehl, Georg H; Glorieux, Christ; Thoen, Jan

    2008-07-01

    High-resolution adiabatic scanning calorimetry and differential scanning calorimetry have been employed to study the thermal behavior of an organo-siloxane tetrapode reported to exhibit a biaxial nematic phase. No signature of the uniaxial to biaxial nematic phase transition could be retraced in sequential heating and cooling runs under different scanning rates, within the experimental resolution. The results obtained reveal that an extremely small heat should be involved in the uniaxial to biaxial nematic phase transition. The isotropic to uniaxial nematic transition at 318+/-0.01 K is very stable, and it is weakly first order with a rather small latent heat of 0.20+/-0.02 J/g . PMID:18763974

  18. Characterization of stationary phases for gas chromatography by 29Si nuclear magnetic resonance spectroscopy III. Carborane-siloxane copolymers.

    PubMed

    Kählig, Hanspeter; Mayer-Helm, Bernhard X

    2006-10-27

    Five bis(dimethylsilyl)-m-carborane-siloxane polymers with methyl, phenyl, and 2-cyanoethyl ligands were characterized by (1)H, (11)B, (13)C, and (29)Si nuclear magnetic resonance (NMR) spectroscopy. All relevant chemical shifts are reported, whereas signal assignment was confirmed by 2D NMR spectroscopy. The chemical composition of the polymers was calculated from the (1)H and (29)Si NMR spectra. Only (29)Si NMR spectroscopy was able to quantify the methoxy end group, from which the average molecular weights were calculated. The copolymer Dexsil 300 turned out to have a regular microstructure, whilst the terpolymers Dexsil 400 and Dexsil 410 have only partly regular sequences. (11)B NMR spectroscopy confirmed the m-carborane structure and revealed some low molecular weight impurities. PMID:16919648

  19. Evaluation of properties of irreversible hydrocolloid impression materials mixed with disinfectant liquids

    PubMed Central

    Amalan, Arul; Ginjupalli, Kishore; Upadhya, Nagaraja

    2013-01-01

    Background: Addition of disinfectant to irreversible hydrocolloid impression materials can eliminate the disinfection step to avoid dimensional changes associated with it. The aim of the present study was to evaluate the effect of various disinfectant mixing liquids on the properties of commercially available irreversible hydrocolloid impression materials. Materials and Methods: Four commercially available irreversible hydrocolloid impression materials (Zelgan, Vignette, Tropicalgin, and Algitex) were mixed with disinfectant liquid containing chlorhexidine (0.1 and 0.2%) and sodium hypochlorite (0.1 and 0.5%). After mixing with disinfectant liquids, materials were evaluated for pH changes during gelation, gelation time, flow, gel strength, permanent deformation and detail reproduction. Results: Significant changes in gelation time were observed in irreversible hydrocolloid impression materials upon mixing with disinfectant liquids. In general, chlorhexidine increased the gelation time, whereas sodium hypochlorite reduced it. However, no significant changes in the flow were observed both with chlorhexidine and sodium hypochlorite. Gel strength was found to decrease when mixed with chlorhexidine, whereas an increase in gel strength was observed upon mixing with sodium hypochlorite. Permanent deformation of the most irreversible hydrocolloid impression materials was below the specification limit even after mixing with disinfectant liquids. Sodium hypochlorite significantly reduced the surface detail reproduction, whereas no change in detail reproduction was observed with chlorhexidine. Conclusion: Chlorhexidine solution can be used to mix irreversible hydrocolloid impression materials in regular dental practice as it did not significantly alter the properties. This may ensure effective disinfection of impressions. PMID:23878566

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

    SciTech Connect

    Hsu, L.; Philipp, W.H.; Sheibley, D.W.

    1981-06-09

    A film-forming polyvinyl alcohol polymer is mixed with a polyaldehyde-polysaccharide cross-linking agent having at least two monosaccharide units and a plurality of aldehyde groups per molecule, preferably an average of at least one aldehyde group per monosaccharide units. The cross-linking agent, such as a polydialdehyde starch, is used in an amount of about 2.5 to 20% of the theoretical amount required to cross-link all of the available hydroxyl groups of the polyvinyl alcohol polymer. Reaction between the polymer and cross-linking agent is effected in aqueous acidic solution to produce the cross-linked polymer. The polymer product has low electrical resistivity and other properties rendering it suitable for making separators for alkaline batteries. In that event, the mixture of polymer and cross-linking agent is formed into a sheet or film or the like and the film is cut to size and otherwise fabricated into a configuration suitable for a particular end use. The crosslinking reaction is then carried out to produce the final product.

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

    PubMed

    Cehreli, Murat C; Akça, Kivanç

    2006-08-01

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

  2. Comparison of Different Final Impression Techniques for Management of Resorbed Mandibular Ridge: A Case Report

    PubMed Central

    Yadav, Bhupender; Jayna, Manisha; Yadav, Harish; Suri, Shrey; Phogat, Shefali; Madan, Reshu

    2014-01-01

    The history of complete denture impression procedures has been influenced largely by the development of impression materials from which new techniques and ideas arose. The purpose of this study was to compare the retention of complete dentures made by using different impression techniques like conventional, admixed, all green, and functional techniques. The results showed that there was significant difference in retention between the six techniques where functional technique showed the highest mean value of retention followed by elastomeric, all green, and admixed, while cocktail and green stick compound showed the lowest mean value. However, on clinical examination, the retention produced by the six techniques was satisfactory. PMID:25180105

  3. Comparison of digital and conventional impression techniques: evaluation of patients’ perception, treatment comfort, effectiveness and clinical outcomes

    PubMed Central

    2014-01-01

    Background The purpose of this study was to compare two impression techniques from the perspective of patient preferences and treatment comfort. Methods Twenty-four (12 male, 12 female) subjects who had no previous experience with either conventional or digital impression participated in this study. Conventional impressions of maxillary and mandibular dental arches were taken with a polyether impression material (Impregum, 3 M ESPE), and bite registrations were made with polysiloxane bite registration material (Futar D, Kettenbach). Two weeks later, digital impressions and bite scans were performed using an intra-oral scanner (CEREC Omnicam, Sirona). Immediately after the impressions were made, the subjects’ attitudes, preferences and perceptions towards impression techniques were evaluated using a standardized questionnaire. The perceived source of stress was evaluated using the State-Trait Anxiety Scale. Processing steps of the impression techniques (tray selection, working time etc.) were recorded in seconds. Statistical analyses were performed with the Wilcoxon Rank test, and p?impressions were more comfortable than conventional techniques. Conclusions Digital impressions resulted in a more time-efficient technique than conventional impressions. Patients preferred the digital impression technique rather than conventional techniques. PMID:24479892

  4. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3661 Optical Impression Systems for CAD...computer-assisted design and manufacturing of dental restorative prosthetic devices. Such systems may consist of a camera,...

  5. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3661 Optical Impression Systems for CAD...computer-assisted design and manufacturing of dental restorative prosthetic devices. Such systems may consist of a camera,...

  6. 21 CFR 872.3661 - Optical Impression Systems for CAD/CAM.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3661 Optical Impression Systems for CAD...computer-assisted design and manufacturing of dental restorative prosthetic devices. Such systems may consist of a camera,...

  7. Modern and Fossil Raindrop Impressions as a Lesson in Interpretation of Ancient Sedimentary Features.

    ERIC Educational Resources Information Center

    Pardi, Richard R.; Brickner, Dorene

    1990-01-01

    Procedures for duplicating fossil raindrop impressions are presented. The use of modern and fossil imprints as the basis for qualitative and quantitative lessons in the interpretation of ancient sedimentary features is discussed. (CW)

  8. Impression materials and techniques for crown and bridgework: a survey of undergraduate teaching in the UK.

    PubMed

    Randall, R C; Wilson, M A; Setcos, J C; Wilson, N H

    1998-06-01

    The aim of this study was to document the teaching of impression materials and techniques for crown and bridgework in the undergraduate curriculum in UK dental schools. A questionnaire sent to each school during the 1993/1994 academic year elicited fourteen replies (100% response). Addition-cured silicones were found to predominate; 71% of schools taught and used clinically a one-stage, full arch impression technique involving stock trays, and 57% of schools a full-arch custom tray technique. Routine disinfection of impressions was taught and practised in 43% of schools. The results demonstrated variation between UK dental schools in their teaching of impression materials and techniques for crown and bridgework in the undergraduate curriculum. PMID:9927922

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

    Microsoft Academic Search

    Nicolai A. Christiansen; Emanuel Tschopp

    2010-01-01

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

  10. Impression technique for monitoring and virtual treatment planning in nasoalveolar moulding.

    PubMed

    Loeffelbein, Denys J; Rau, Andrea; Wolff, Klaus-Dietrich

    2013-12-01

    We describe our experience with various silicone materials for making one-step and two-step impressions of the cleft-lip-palate-nose complex during nasoalveolar moulding. Our technique is superior to common alginate-based impression techniques, as it provides precise reproduction of the complex anatomy of the cleft, and is compatible with the latest available methods of planning treatment with nasoalveolar moulding, such as computer-aided reverse engineering and rapid prototyping. PMID:23414909

  11. Impression creep of hypoeutectic Sn–Zn lead-free solder alloys

    Microsoft Academic Search

    R. Mahmudi; A. R. Geranmayeh; H. Noori; M. Shahabi

    2008-01-01

    Creep behavior of the hypoeutectic Sn–Zn alloys containing 2.5–6.5wt.%Zn was studied by impression testing and compared to that of the eutectic Sn–9Zn alloy. The tests were carried out under constant punching stress in the range 50–110MPa and at temperatures in the range 298–370K. Assuming a power law relationship between the impression rate and stress, average stress exponents of 6.2, 6.4,

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

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

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

  13. Effect of plasma treatment on the wettability of elastomeric impression materials.

    PubMed

    Vassilakos, N; Fernandes, C P; Nilner, K

    1993-08-01

    This study investigated the effect of "plasma treatment" on the wettability of impression materials and void formation in die stone casts. Four addition reaction silicones, one condensation reaction silicone, and one polyether impression material were used. Wettability was determined before and after plasma treatment by contact angle registration of a saturated aqueous solution of calcium sulfate (CaSO4) on flat surfaces made from the tested impression materials. Two groups of surfaces were used for each material. The surfaces in one of the groups were exposed to saliva for 5 minutes. The same impression materials were used to produce four groups of die stone casts from a master die. Two groups were produced from impressions that had been exposed to milk. One group from the exposed and one from the bare surfaces were plasma-treated before pouring. Voids in the stone casts were counted under a stereoscopic microscope. The results indicated that after plasma treatment, the drop of CaSO4 solution completely spread over the addition type silicone surfaces. The corresponding die stone casts were found to be void free. It was concluded that plasma treatment produced high-energy impression surfaces that result in void-free die stone casts from the addition type silicone materials. PMID:8371180

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

    PubMed Central

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

    2014-01-01

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

  15. Effect of mixing techniques on bacterial attachment and disinfection time of polyether impression material

    PubMed Central

    Guler, Umut; Budak, Yasemin; Ruh, Emrah; Ocal, Yesim; Canay, Senay; Akyon, Yakut

    2013-01-01

    Objective: The aim of this study was 2-fold. The first aim was to evaluate the effects of mixing technique (hand-mixing or auto-mixing) on bacterial attachment to polyether impression materials. The second aim was to determine whether bacterial attachment to these materials was affected by length of exposure to disinfection solutions. Materials and Methods: Polyether impression material samples (n = 144) were prepared by hand-mixing or auto-mixing. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were used in testing. After incubation, the bacterial colonies were counted and then disinfectant solution was applied. The effect of disinfection solution was evaluated just after the polymerization of impression material and 30 min after polymerization. Differences in adherence of bacteria to the samples prepared by hand-mixing and to those prepared by auto-mixing were assessed by Kruskal-Wallis and Mann-Whitney U-tests. For evaluating the efficiency of the disinfectant, Kruskal-Wallis multiple comparisons test was used. Results: E. coli counts were higher in hand-mixed materials (P < 0.05); no other statistically significant differences were found between hand- and auto-mixed materials. According to the Kruskal-Wallis test, significant differences were found between the disinfection procedures (Z > 2.394). Conclusion: The methods used for mixing polyether impression material did not affect bacterial attachment to impression surfaces. In contrast, the disinfection procedure greatly affects decontamination of the impression surface. PMID:24966729

  16. X-ray analysis of poly(vinyl fluoride)

    SciTech Connect

    Lando, J.B. [Case Western Reserve Univ., Cleveland, OH (United States). Dept. of Macromolecular Science; Hanes, M.D. [Phillips Petroleum, Bartlesville, OK (United States)

    1995-02-13

    Three different X-ray analysis technique were used to investigate the chain defect content present in the crystalline regions of poly(vinyl fluoride). The techniques used were a fiber pattern analysis, a powder pattern analysis, and a meridional intensity analysis. The fiber pattern analysis proved unable to determine either the tacticity or regic defect content in PVF. However, it was found that the refinement favored a statistical packing of the chains in the crystalline regions. This packing arrangement was supported by the powder pattern analysis and molecular modeling calculations. The meridional intensity analysis proved to be sensitive to the regic defect content of the sample. The results of this analysis correlated well with previous DSC work.

  17. Vitrification of Polyvinyl Chloride Waste from Korean Nuclear Power Plants

    SciTech Connect

    Sheng, Jiawei [Kyoto University (Japan); Choi, Kwansik [Nuclear Environment Technology Institute (Korea, Republic of); Yang, Kyung-Hwa [Nuclear Environment Technology Institute (Korea, Republic of); Lee, Myung-Chan [Nuclear Environment Technology Institute (Korea, Republic of); Song, Myung-Jae [Nuclear Environment Technology Institute (Korea, Republic of)

    2000-02-15

    Vitrification is considered as an economical and safe treatment technology for low-level radioactive waste (LLW) generated from nuclear power plants (NPPs). Korea is in the process of preparing for its first ever vitrification plant to handle LLW from its NPPs. Polyvinyl chloride (PVC) has the largest volume of dry active wastes and is the main waste stream to treat. Glass formulation development for PVC waste is the focus of study. The minimum additive waste stabilization approach has been utilized in vitrification. It was found that glasses can incorporate a high content of PVC ash (up to 50 wt%), which results in a large volume reduction. A glass frit, KEP-A, was developed to vitrify PVC waste after the optimization of waste loading, melt viscosity, melting temperature, and chemical durability. The KEP-A could satisfactorily vitrify PVC with a waste loading of 30 to 50 wt%. The PVC-frit was tolerant of variations in waste composition.

  18. Cross-linked polyvinyl alcohol films as alkaline battery separators

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.; Manzo, M. A.; Gonzalez-Sanabria, O. D.

    1982-01-01

    Cross-linking methods were investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: (1) PVA-dialdehyde blends post-treated with an acid or acid periodate solution (two-step method) and (2) PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality (one-step method). Laboratory samples of each cross-linked type of film were prepared and evaluated in standard separator screening tests. The pilot-plant batches of films were prepared and compared to measure differences due to the cross-linking method. The pilot-plant materials were then tested in nickel oxide - zinc cells to compare the two methods with respect to performance characteristics and cycle life. Cell test results are compared with those from tests with Celgard.

  19. Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets

    NASA Technical Reports Server (NTRS)

    Annamalai, P.; Lee, M. C.; Crawley, R. L.; Downs, R. L.

    1985-01-01

    An inertial confinement fusion (ICF) target made of polystyrene is first levitated in an acoustic field. The surface of the target is then etched using an appropriate solution (e.g., cyclohexane) to enhance the wetting characteristics. A specially prepared polyvinyl alcohol solution is atomized using an acoustic atomizer and deposited on the surface of the target. The solution is air dried to form a thin coating (2 microns) on the target (outside diameter of about 350-850 microns). Thicker coatings are obtained by repeated applications of the coating solutions. Preliminary results indicate that uniform coatings may be achievable on the targets with a background surface smoothness in the order of 1000 A.

  20. Cross-linked polyvinyl alcohol films as alkaline battery separators

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.; Manzo, M. A.; Gonzalez-Sanabria, O. D.

    1983-01-01

    Cross-linking methods have been investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: (1) PVA-dialdehyde blends post-treated with an acid or acid periodate solution (two-step method) and (2) PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality (one-step method). Laboratory samples of each cross-linked type of film were prepared and evaluated in standard separator screening tests. Then pilot-plant batches of films were prepared and compared to measure differences due to the cross-linking method. The pilot-plant materials were then tested in nickel oxide-zinc cells to compare the two methods with respect to performance characteristics and cycle life. Cell test results are compared with those from tests with Celgard.

  1. Biodegradable thermoplastic composites based on polyvinyl alcohol and algae.

    PubMed

    Chiellini, Emo; Cinelli, Patrizia; Ilieva, Vassilka I; Martera, Martina

    2008-03-01

    Algae constitute a largely available, low value material from renewable resources of marine origin to be used for the production of eco-compatible composites. Fibers of the green alga Ulva armoricana from the French coast were positively evaluated for the production of composites with a hydrophilic, eco-compatible polymer, such as poly(vinyl alcohol) (PVA) as continuous matrix by casting of aqueous suspensions and compression molding. PVA, Ulva, and starch were also successfully processed by the melt in the presence of glycerol. Positive results were obtained for film-forming properties and mechanical characteristics also with limited amounts of PVA (40%) attesting for Ulva suitability to be introduced in composites (up to 30%). Degradation in soil of Ulva and an Ulva-based composites outlined a rapid mineralization of Ulva in the selected medium (over 80% in 100 days) while the composite samples underwent a mineralization rate affected by the different component propensity to degradation. PMID:18257530

  2. Cross-linked polyvinyl alcohol films as alkaline battery separators

    SciTech Connect

    Sheibley, D.W.; Manzo, M.A.; Gonzalez-Sanabria, O.D.

    1982-03-01

    Cross-linking methods were investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: (1) PVA-dialdehyde blends post-treated with an acid or acid periodate solution (two-step method) and (2) PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality (one-step method). Laboratory samples of each cross-linked type of film were prepared and evaluated in standard separator screening tests. The pilot-plant batches of films were prepared and compared to measure differences due to the cross-linking method. The pilot-plant materials were then tested in nickel oxide - zinc cells to compare the two methods with respect to performance characteristics and cycle life. Cell test results are compared with those from tests with Celgard.

  3. Cross-linked polyvinyl alcohol films as alkaline battery separators

    SciTech Connect

    Sheibley, D.W.; Gonzalez-Sanabria, O.D.; Manzo, M.A.

    1983-02-01

    Cross-linking methods have been investigated to determine their effect on the performance of polyvinyl alcohol (PVA) films as alkaline battery separators. The following types of cross-linked PVA films are discussed: PVA-dialdehyde blends post-treated with an acid or acid periodate solution and PVA-dialdehyde blends cross-linked during film formation (drying) by using a reagent with both aldehyde and acid functionality. Laboratory samples of each cross-linked type of film were prepared and evaluated in standard separator screening tests. Then pilotplant batches of films were prepared and compared to measure differences due to the cross-linking method. The pilot-plant materials were then tested in nickel oxide-zinc cells to compare the two methods with respect to performance characteristics and cycle life. Cell test results are compared with those from tests with Celgard.

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

    Microsoft Academic Search

    Jae Hyung Park; You Han Bae

    2002-01-01

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

  5. FT?IR Study of the Hydrolysis and Polymerization of Tetraethyl Orthosilicate and Polydimethyl Siloxane in the Presence of Tetrabutyl Orthotitanate

    Microsoft Academic Search

    L. Téllez; J. Rubio; F. Rubio; E. Morales; J. L. Oteo

    2004-01-01

    In this work, we have used FT?IR spectroscopy to study the hydrolysis and polymerization reactions of tetraethyl orthosilicate (TEOS) and polydimethyl?siloxane (PDMS) in the presence of tetrabutyl orthotitanate (TBOT). These reactions are used for obtaining SiO2–PDMS–TiO2 organically modified silicates (Ormosils). In order to obtain semi?quantitative information about such reactions, a deconvolution procedure of the FT?IR spectra has been done by

  6. The Study for Improving the Dielectric Strength and Lowering the Low-molecular-weight Siloxane of PDMS based Materials by Organic-inorganic Hybrid Method

    Microsoft Academic Search

    Yusuke Aoki; Hidenori Kubo; Takuya Shindou

    2010-01-01

    We have investigated the thermal endurance and electrical insulating properties and mechanical properties of PDMS-based hybrid materials made from ethoxy-terminated PDMS and various metal alkoxides for application as electrical insulating encapsulants. The materials exhibited good thermal stability and good electrical insulating properties. The amount of all dimethyl cyclic siloxanes evaporated at 200°C from PDMS based hybrid were found to be

  7. Growth characteristics of selected fungi on polyvinyl film

    SciTech Connect

    Roberts, W.T.; Davidson, P.M.

    1986-04-01

    The objective of this study was to determine if plasticized polyvinyl chloride film would support the growth of any of nine species of fungi. The film was suspended in distilled water with no nutrients or with glucose or ammonium sulfate. Spores of each of the test species were inoculated into the suspension medium, and the mixture was incubated at 30/sup 0/C for up to 18 weeks. Most species were found to be capable of utilizing the film for carbon or nitrogen when the other nutrient was supplied. Only two species, Aspergillus fischeri and Paecilomyces sp., were found to be capable of utilizing components of the film without added nutrients. Components of the polyvinyl chloride film were then incorporated into mineral salts medium to determine if these components could serve as carbon sources in the presence of ammonium nitrate. The only component found to be utilized by all the fungi as a carbon source was epoxidized oil, a plasticizer-stabilizer. Calcium-zinc stearate was an available carbon source for all except the Penicillium and Verticillium strains. The only other component utilized was a stearamide, which was metabolized solely by the Aspergillus sp. Only the stearamide contained enough nitrogen to serve as a primary source in the film. The compound, however, did not support growth of fungi in the presence of glucose. It was theorized that either the nitrogen of the stearamide was more readily available to the fungi in the whole film due to the presence of trace nutrients or the nitrogen was supplied by exogenous sources.

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  9. Synthesis and properties of a novel UV-cured fluorinated siloxane graft copolymer for improved surface, dielectric and tribological properties of epoxy acrylate coating

    NASA Astrophysics Data System (ADS)

    Yan, Zhenlong; Liu, Weiqu; Gao, Nan; Wang, Honglei; Su, Kui

    2013-11-01

    A novel functional fluorinated siloxane graft copolymer bearing with vinyl end-groups was synthesized from dihydroxypropyl-terminated poly(dimethylsiloxane) (PDMS), dicarboxyl terminated poly(2,2,3,4,4,4-hexafluorobutyl acrylate) oligomer (CTHFA), 2,4-toluene diissocyanate (TDI) and 2-hydroxyethyl methacrylate (HEMA). The chemical structure was characterized by FT-IR and GPC. The effect of concentration of the vinyl-capped fluorosilicone graft copolymer (Vi-PFSi) on the surface, thermal properties, dielectric and tribological properties of UV-cured films was investigated. Contact angles and surface energies showed that the high hydrophobic and oleophobic surfaces were obtained by incorporation of Vi-PFSi at very low amount (0.5 wt%). X-ray photoelectron spectroscopy (XPS) evidenced that the fluorinated and siloxane moiety selectively migrated to the outermost surface of UV-cured film, thus reduced its surface energy from 45.42 to 15.40 mN/m2 without affecting its bulk properties. The morphology of fracture surface of modified film exhibited rough fracture surface only at the outermost surface, revealing fluorinated and siloxane groups migrated toward air-side surface. The dielectric constants decreased from 5.32 (1 MHz) for bisphenol-A epoxy methacrylate (EMA) to 2.82 (1 MHz) for modified film when the Vi-PFSi copolymer concentration increased from 0 to 0.8 wt%. Tribological results from abrasion tester suggested that the Vi-PFSi could obviously reduce the abrasion weight loss of modified films.

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

    E-print Network

    Sample, Caitlin (Caitlin Sarah)

    2014-01-01

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

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

    E-print Network

    Kroenig, Andrea N

    1997-01-01

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

  12. Poly(vinyl chloride) (PVC) hollow fiber ultrafiltration membranes prepared from PVC\\/additives\\/solvent

    Microsoft Academic Search

    Jian Xu; Zhen-Liang Xu

    2002-01-01

    Using poly(vinyl pyrrolidone) (PVP 40,000) or poly(ethylene glycol) (PEG) with different molecular weights (PEG 600, PEG 800, PEG 1000) as additives and N,N-dimethylacetamide (DMAc) as a solvent, asymmetric poly(vinyl chloride) (PVC) hollow fiber ultrafiltration membranes were prepared by phase inversion technique from 14 to 20wt.% solids including PVC and additives. The 95\\/5 DMAc\\/water and pure water were used as the

  13. Carboxymethylcellulose and poly(vinyl alcohol) used as a film support for lipases immobilization

    Microsoft Academic Search

    Roberto Dalla-Vecchia; Damianni Sebrão; Maria da Graça Nascimento; Valdir Soldi

    2005-01-01

    Lipases from 10 different sources were immobilized on poly(vinyl alcohol) (PVA), carboxymethycellulose (CMC) and poly(vinyl alcohol):carboxymethycellulose blend (50:50% m\\/m) and used as biocatalysts in esterification reactions of carboxylic acids with n-pentanol in organic media. Among the tested lipases, higher yields in n-pentyl laurate were obtained when lipases from Mucor javanicus (MJL) or Rhyzopus oryzae (ROL) were immobilized in CMC, PVA

  14. Novel Poly(vinyl alcohol)\\/Clay Nanocomposite Microspheres via Suspension Polymerization and Saponification

    Microsoft Academic Search

    Jeong Hyun Yeum

    2011-01-01

    Poly(vinyl alcohol) (PVA)\\/montmorillonite (MMT) clay nanocomposite microspheres were synthesized through suspension polymerization followed by the heterogeneous saponification for the first time. The effects of MMT on the saponification rate of poly(vinyl acetate) (PVAc) microspheres were studied. It was found that the saponification rate of PVAc significantly increased in the presence of MMT particles. The molecular weight of extracted PVA from

  15. Semi-interpenetrating polymer networks based on polyaniline and polyvinyl alcohol–glutaraldehyde

    Microsoft Academic Search

    W. M de Azevedo; J. M de Souza; J. V de Melo

    1999-01-01

    A new semi-Interpenetrating Polymer Network (semi-IPN) based on polyvinyl alcohol–glutaraldehyde\\/polyaniline was synthesized and characterized by spectroscopic analysis in the UV–Visible–Infrared region and by scanning electron microscopy (SEM). The semi-IPNs exhibit good mechanical properties, characteristic of polyvinyl alcohol–glutaraldehyde polymer network, and excellent optical properties. The UV–Visible results show that the optical properties of the semi-IPNs are characteristic only of polyaniline polymer,

  16. Electrospinning and characterization of medium-molecular-weight poly(vinyl alcohol)\\/high-molecular-weight poly(vinyl alcohol)\\/montmorillonite nanofibers

    Microsoft Academic Search

    Hyun Mi Ji; Hyun Woo Lee; Mohammad Rezaul Karim; In Woo Cheong; Eun A. Bae; Tae Hun Kim; Byung Chul Ji; Jeong Hyun Yeum

    2009-01-01

    Submicron fibers of medium-molecular-weight poly(vinyl alcohol) (MMW-PVA), high-molecular-weight poly(vinyl alcohol) (HMW-PVA),\\u000a and montmorillonite clay (MMT) in aqueous solutions were prepared by electrospinning technique. The effect of HMW-PVA and\\u000a MMT on the morphology and mechanical properties of the MMW-PVA\\/HMW-PVA\\/MMT nanofibers were investigated for the first time.\\u000a Scanning electron microscopy, viscometer, tensile strength testing machine, thermal gravimetric analyzer (TGA), and transmission\\u000a electron

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

    PubMed

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

    2013-09-01

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

  18. How Do You Say ‘Hello’? Personality Impressions from Brief Novel Voices

    PubMed Central

    McAleer, Phil; Todorov, Alexander; Belin, Pascal

    2014-01-01

    On hearing a novel voice, listeners readily form personality impressions of that speaker. Accurate or not, these impressions are known to affect subsequent interactions; yet the underlying psychological and acoustical bases remain poorly understood. Furthermore, hitherto studies have focussed on extended speech as opposed to analysing the instantaneous impressions we obtain from first experience. In this paper, through a mass online rating experiment, 320 participants rated 64 sub-second vocal utterances of the word ‘hello’ on one of 10 personality traits. We show that: (1) personality judgements of brief utterances from unfamiliar speakers are consistent across listeners; (2) a two-dimensional ‘social voice space’ with axes mapping Valence (Trust, Likeability) and Dominance, each driven by differing combinations of vocal acoustics, adequately summarises ratings in both male and female voices; and (3) a positive combination of Valence and Dominance results in increased perceived male vocal Attractiveness, whereas perceived female vocal Attractiveness is largely controlled by increasing Valence. Results are discussed in relation to the rapid evaluation of personality and, in turn, the intent of others, as being driven by survival mechanisms via approach or avoidance behaviours. These findings provide empirical bases for predicting personality impressions from acoustical analyses of short utterances and for generating desired personality impressions in artificial voices. PMID:24622283

  19. How do you say 'hello'? Personality impressions from brief novel voices.

    PubMed

    McAleer, Phil; Todorov, Alexander; Belin, Pascal

    2014-01-01

    On hearing a novel voice, listeners readily form personality impressions of that speaker. Accurate or not, these impressions are known to affect subsequent interactions; yet the underlying psychological and acoustical bases remain poorly understood. Furthermore, hitherto studies have focussed on extended speech as opposed to analysing the instantaneous impressions we obtain from first experience. In this paper, through a mass online rating experiment, 320 participants rated 64 sub-second vocal utterances of the word 'hello' on one of 10 personality traits. We show that: (1) personality judgements of brief utterances from unfamiliar speakers are consistent across listeners; (2) a two-dimensional 'social voice space' with axes mapping Valence (Trust, Likeability) and Dominance, each driven by differing combinations of vocal acoustics, adequately summarises ratings in both male and female voices; and (3) a positive combination of Valence and Dominance results in increased perceived male vocal Attractiveness, whereas perceived female vocal Attractiveness is largely controlled by increasing Valence. Results are discussed in relation to the rapid evaluation of personality and, in turn, the intent of others, as being driven by survival mechanisms via approach or avoidance behaviours. These findings provide empirical bases for predicting personality impressions from acoustical analyses of short utterances and for generating desired personality impressions in artificial voices. PMID:24622283

  20. Survey of Impression Materials and Techniques in Fixed Partial Dentures among the Practitioners in India

    PubMed Central

    Moldi, Arvind; Puranik, Shivakumar; Karan, Smita; Deshpande, Sumit; Neela, Neelima

    2013-01-01

    Objective. Anecdotal evidence suggests that impression materials and techniques used in general dental practice for fixed partial dentures vary from those taught in dental schools. The aim of this survey was to integrate impression techniques evolved all over the years for fixed partial dentures and to know the techniques and materials which are used in the present day by the practitioners. Materials and Methods. A total of 1000 questionnaires were sent to various practitioners in India, out of which 807 questionnaires were filled. Results. The results showed that 84.8% of prosthodontists (65.56%, urban areas) use elastomeric impression materials as well as irreversible hydrocolloids and 15.2% use irreversible hydrocolloid only. Amongst other practitioners, 55.46% use irreversible hydrocolloid (45%, rural and semiurban areas) and 44.54% use elastomeric impression materials. Elastomeric impression technique practiced most commonly is putty reline with/without spacer (77.2%); other techniques are multiple-mix and monophase techniques. Conclusion. The ideal materials, technique, and armamentarium are required for the long-term success of the treatment for fixed partial denture. Also, if the ideal procedure is not followed, it will lead to a compromised fit of the final prosthesis and failure of the treatment. PMID:23691334

  1. Forming a negative impression of another person correlates with activation in medial prefrontal cortex and amygdala

    PubMed Central

    Harada, Tokiko; Sadato, Norihiro

    2011-01-01

    Neural correlates involved in the formation of negative impression from face were investigated using event-related functional magnetic resonance imaging and a partial conditioning paradigm. Eighteen normal volunteers underwent imaging while they viewed the faces of two unfamiliar individuals: one individual’s face was partially accompanied by negative emotion but the other’s was not. After the volunteers learned the relationship between the faces and the emotion, they formed a more negative impression of the person’s face when the emotion was presented. Subtraction analysis of the individuals’ neutral faces revealed activation in the dorsal anterior cingulate cortex and superior temporal sulcus, but this activity did not correlate with the change of impression from face. On the other hand, the response in the left amygdala negatively correlated with the change of impression from face in the first run. Time modulation analysis revealed that activity in the dorsomedial prefrontal cortex associated with negative emotion was the largest in the initial part of the acquisition. These results suggest that a negative impression from face may be formed by orchestrated activity in the dorsomedial prefrontal cortex, dorsal anterior cingulate cortex and amygdala, and that the activity has a prominent role in the initial acquisition of negative emotion. PMID:20693390

  2. Synthesis of anion receptor grafted siloxane polymers and the ionic conductivity studies of polymer-salt complexes

    SciTech Connect

    Lee, H.S.; Yang, X.Q.; Xiang, C.; McBreen, J. [Brookhaven National Lab., Upton, NY (United States)] [Brookhaven National Lab., Upton, NY (United States); Callahan, J.H.; Choi, L.S. [Naval Research Lab., Washington, DC (United States)] [Naval Research Lab., Washington, DC (United States)

    1999-03-01

    A new type of ionic conducting polymers has been synthesized by grafting anion receptors on siloxane polymer backbones. The polymer electrolytes were formed by complexing these polymers with LiCl salt. The room temperature conductivity is in the range of 7 {times} 10{sup {minus}8} to 4 {times} 10{sup {minus}6} S/cm and depends on the structures of grafted anion receptors and the polymer backbones. These values are close to the conductivities of poly(ethylene oxide)-based polymer electrolytes. The temperature dependence of the ionic conductivity of these polymer electrolytes was also studied. The unique feature and an interesting point of this new type of polymer electrolytes is that the ion complexation is formed between the attached anion receptors and the anions, and there are no ethylene oxide groups in these polymers. The anion receptors are based on aza-ether structures with electron-withdrawing groups attached on them. In contrast to this, in poly(ethylene oxide)-based electrolyte systems, the complexation is formed between the oxygen atoms in the ethylene oxide groups of the polymer and the cations. The complexation between the anion receptors and anions in this new type of polymer electrolytes was confirmed by near edge X-ray absorption fine structure spectra.

  3. Mechanics of plasma exposed spin-on-glass (SOG) and polydimethyl siloxane (PDMS) surfaces and their impact on bond strength

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Shantanu; Gao, Yuanfang; Korampally, Venumadhav; Othman, M. T.; Grant, Sheila A.; Gangopadhyay, Keshab; Gangopadhyay, Shubhra

    2007-02-01

    Silicone polymer (PDMS), widely used for micro-fluidic and biosensor applications, possesses an extremely dynamic surface after it is subjected to an oxygen plasma treatment process. The surface becomes extremely hydrophilic immediately after oxygen plasma exposure by developing silanol bond (Si sbnd OH), which promotes its adhesion to some other surfaces like, silicon, silicon dioxide, glass, etc. Such a surface, if left in ambient dry air, shows a gradual recovery of hydrophobicity. We have found an identical behavior to occur to surfaces coated with a thin continuous film of SOG (methyl silsesquioxane). The chemistry induced by oxygen plasma treatment of a spin-on-glass (SOG) coated surface provides a much higher density of surface silanol groups in comparison to precleaned glass, silicon or silicon dioxide substrates thus providing a higher bond strength with polydimethyl siloxane (PDMS). The bonding protocol developed by using the spin coated and cured SOG intermediate layer provides an universal regime of multi level wafer bonding of PDMS to a variety of substrates. The paper describes a contact angle based estimation of bond strength for SOG and PDMS surfaces exposed to various combinations of plasma parameters. We have found that the highest bond strength condition is achieved if the contact angle on the SOG surface is less than 10°.

  4. Siloxanes removal from biogas by a lab-scale biotrickling filter inoculated with Pseudomonas aeruginosa S240.

    PubMed

    Li, Yunhui; Zhang, Weijiang; Xu, Jiao

    2014-06-30

    Removing volatile methyl siloxanes (VMSs) from biogas remains a longstanding challenge in the field of biological process due to their low bioavailability and biodegradation. To address this issue, a lab-scale aerobic biotrickling filter, packed with porous lava and inoculated with an effective strain of Pseudomonas aeruginosa, was developed and its performance for octamethylcyclotetrasiloxane (D4, selected as a model VMS) removal from an aerobic synthetic gas was monitored. The biotrickling filter exhibited a relatively high removal efficiency over 74% at empty bed residence time of 13.2 min. Rhamnolipids, biosurfactants produced by P. aeruginosa, were identified in the liquid phase of the biotrickling filter by HPLC-MS and ATR-FTIR, and they were found to be the main factor of improving D4 removal. Moreover, dimethylsilanediol, methanol, silicic acid in the liquid phase and carbon dioxide in the gas phase, as the biodegradation products of D4, were determined by GC-MS, silicic acid analysis and non-dispersive infrared analysis. To our knowledge, it is the first time to report the existence of methanol in the D4 degradation products. Finally, a metabolic pathway for D4 degradation by P. aeruginosa was proposed based on our results. PMID:24857900

  5. Preparation and characterization of fused-silica capillary columns coated with m-carborane-siloxane copolymers for gas chromatography.

    PubMed

    Petsch, Martina; Mayer-Helm, Bernhard X; Söllner, Verena

    2005-09-01

    The carborane-siloxane copolymers Dexsil 300, a 34.5% bis(dimethylsilyl)-m-carborane-65.5% dimethylsiloxane copolymer, and Dexsil 400, a 24.9% bis(dimethylsilyl)-m-carborane-50.8% dimethyl, 24.3% methylphenylsiloxane copolymer, were coated on fused silica capillary columns and their gas chromatographic properties were evaluated. Their selectivity was evaluated using both Rohrschneider-McReynolds constants and triacylglycerol indices. The bis(dimethylsilyl)-m-carborane unit turned out to be equivalent to two dimethylsiloxy units and one half of a diphenylsiloxy unit. The m-carborane unit was found to cause a 15-25 K shift in the elution temperature between 120 and 360 degrees C. The working range was from 20 and 0 degrees C to 380 degrees C for Dexsil 300 and Dexsil 400, respectively. The column bleeding levels at 380 degrees C were below 20 and 15 pA for Dexsil 300 and Dexsil 400, respectively. PMID:16143857

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

    PubMed

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

    2013-12-17

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

  7. Physicochemical and biological evaluation of poly(ethylene glycol) methacrylate grafted onto poly(dimethyl siloxane) surfaces for prosthetic devices.

    PubMed

    Gonçalves, Sara; Leirós, Ana; van Kooten, Theo; Dourado, Fernando; Rodrigues, Lígia R

    2013-09-01

    Poly(dimethyl siloxane) (PDMS) was surface-polymerized with poly(ethylene glycol)methacrylate (PEGMA) by surface-initiated atom transfer radical polymerization (SI-ATRP) in aqueous media at room temperature. Modification of the PDMS surface followed a three-step procedure: (i) PDMS surface hydroxylation by UV/ozone exposure, immediately followed by (ii) covalent attachment of the initiator, 1-trichlorosilyl-2-(chloromethylphenyl)ethane, onto the hydroxylated PDMS, via chemical vapor deposition; finally (iii) PDMS surface-polymerization of PEGMA by ATRP. Modified PDMS was characterized by water contact angle measurement, SEM, FTIR-ATR, and XPS. Results showed that modified surfaces had a hydrophilic character, given the water contact angles around 60°; FTIR-ATR and XPS analysis confirmed the presence of polymerized PEGMA on the surface of PDMS and the adhesion of Staphylococcus aureus GB 2/1 and Streptococcus salivarius GB 24/9 onto the modified surfaces was inhibited 94% and 81%, respectively. Finally, the modified PDMS showed no evidence of cytotoxic effects in in vitro assays using human skin fibroblasts. PMID:23660308

  8. Molecular-level insights into the reactivity of siloxane-based electrolytes at a lithium-metal anode.

    PubMed

    Assary, Rajeev S; Lu, Jun; Luo, Xiangyi; Zhang, Xiaoyi; Ren, Yang; Wu, Huiming; Albishri, Hassan M; El-Hady, D Abd; Al-Bogami, A S; Curtiss, Larry A; Amine, Khalil

    2014-07-21

    A molecular-level understanding of the reactions that occur at the lithium-metal anode/electrolyte interphase is essential to improve the performance of Li-O(2) batteries. Experimental and computational techniques are applied to explore the reactivity of tri(ethylene glycol)-substituted trimethylsilane (1NM3), a siloxane-based ether electrolyte, at the lithium-metal anode. In situ/ex situ X-ray diffraction and Fourier-transform infrared spectroscopy studies provide evidence of the formation of lithium hydroxide and lithium carbonates at the anode upon gradual degradation of the metallic lithium anode and the solvent molecules in the presence of oxygen. Density functional calculations performed to obtain a mechanistic understanding of the reductive decomposition of 1NM3 indicate that the decomposition does not require any apparent barrier to produce lithium hydroxide and lithium carbonates when the reduced 1NM3 solvent molecules interact with the oxygen crossing over from the cathode. This study indicates that degradation may be more significant in the case of the 1NM3 solvent, compared to linear ethers such as tetraglyme or dioxalone, because of its relatively high electron affinity. Also, both protection of the lithium metal and prevention of oxygen crossover to the anode are essential for minimizing electrolyte and anode decomposition. PMID:24986260

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    Cyclodextrins (CDs) are cyclic starch molecules having a hollow central cavity which can be threaded by a polymer to form an inclusion compound. This characteristic is exploited in a new type of compatibilizer: a star polymer with a ?tCD core and polystyrene (PS) arms. Atom transfer radical polymerization is used to grow and control the size of the PS arms from brominated initiator sites on ?tCD. Solutions and thin films of PS and poly(dimethyl siloxane) (PDMS) are compatibilized by this CD-star. The mechanism of compatibilization involves threading of the CD core by PDMS and solubilization of the resulting ``slip-ring graft copolymer'' via the PS star arms. Compatibilization of PS/PDMS in chloroform is visually observed when the initially turbid suspensions become clear solutions after addition of CD-star. Thin films spin-cast from these solutions exhibit a high degree of homogeneity and a nanoscale level of mixing. The solutions are characterized with NMR, dynamic light scattering and intrinsic viscosity measurements, and the thin films are characterized with optical and atomic force microscopy. Many different polymers are capable of threading the CD core, thus the same CD-star molecule could be used to compatibilize several different threading polymers with the same matrix polymer.

  10. Stigmatizing materialism: on stereotypes and impressions of materialistic and experiential pursuits.

    PubMed

    Van Boven, Leaf; Campbell, Margaret C; Gilovich, Thomas

    2010-04-01

    Five studies examined the stigmatization of materialism. Participants expressed negative stereotypes of materialistic people, considering them to be more selfish and self-centered than experiential people (Study 1). Participants also viewed materialistic pursuits as more extrinsically motivated than experiential pursuits (Study 2). These stereotypes led respondents from varied demographic backgrounds to form less favorable impressions of individuals who were associated with prototypically materialistic versus experiential purchases, a result that was statistically mediated by impressions that materialistic purchases were more extrinsically motivated (Study 3). These differential impressions are primarily attributable to the denigration of materialistic people rather than the admiration of experiential people (Study 4). The stigmatization of materialism led participants to like less and enjoy interacting less with their conversation partners when discussing materialistic rather than experiential purchases (Study 5). The authors discuss these findings' implications for self-perception, accurate social perception, and well-being. PMID:20363908

  11. Polyvinyl alcohol functionalized cobalt ferrite nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Salunkhe, A. B.; Khot, V. M.; Thorat, N. D.; Phadatare, M. R.; Sathish, C. I.; Dhawale, D. S.; Pawar, S. H.

    2013-01-01

    In the present work, cobalt ferrite nanoparticles (CoFe2O4 NPs) have been synthesized by combustion method. The surface of the CoFe2O4 NPs was modified with biocompatible polyvinyl alcohol (PVA). To investigate effect and nature of coating on the surface of CoFe2O4 NPs, the NPs were characterized X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). The transmission electron microscopy (TEM) and dynamic light scattering (DLS) results demonstrate the monodispersed characteristics of CoFe2O4 NPs after surface modification with PVA. The decrease in contact angle from 162° to 50° with PVA coating on NPs indicates the transition from hydrophobic nature to hydrophilic. The Magnetic properties measurement system (MPMS) results show that the NPs have ferromagnetic behavior with high magnetization of 75.04 and 71.02 emu/g of uncoated and coated CoFe2O4 NPs respectively. These PVA coated NPs exhibit less toxicity over uncoated CoFe2O4 NPs up to 1.8 mg mL-1 when tested with mouse fibroblast L929 cell line.

  12. Oil reclamation from waste plastics including polyvinyl chloride

    SciTech Connect

    Tadauchi, M. [Toshiba Corporation, Yokohama (Japan)

    1995-12-31

    The purpose of this report is to present the results of plant scaleup investigations for oil reclamation from waste plastics. The reclamation process examined was thermal decomposition of polypropylene (PP) and polyvinyl chloride (PVC) under alkali addition and subsequent pressurization. Thermal analyses of the two plastics was performed, indicating that hydrogen chloride evolution occurs at around 300 C and decomposition of PP and oil formation occurs occures arount 450 C. A pilot plant was built and tested with PP and PVC pellets. In accordance with thermal analyses, the temperature of the pyrolysis chamber was raised in two steps. Pilot plant results were compared with bench-scale pilot plant and laboratory experiments. The oil reclamation ratio became smaller with an increase in the volume of the pyrolysis chamber due to temperature distributions and deposition of polymer-alkali residue. Molecular weight distributions of the recovered oil were similar for all three vessels. It was also found that the chlorine concentration in the organic chlorinated compounds in the reclaimed oil stayed below 1/30 that of the oil reclaimed from PVC decomposition without alkali in a laboratory flask-scale vessel.

  13. Dielectric breakdown during Cs+ sputtering of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Wahoud, F.; Guillot, J.; Audinot, J. N.; Bertrand, P.; Delcorte, A.; Migeon, H. N.

    2014-02-01

    Thin films of insulating polymers are sometimes analyzed by secondary ion mass spectrometry (SIMS) or by X-ray photoelectron spectroscopy (XPS) without the use of an electron gun. In this work, both SIMS and XPS have been used to study the chemical and structural modifications due to the charge effect during Cs+ sputtering of a thin film of polyvinyl chloride (PVC). The kinetic energy distribution study shows that at a small primary fluence ˜1015 Cs+ ions/cm2, the dielectric breakdown voltage of the PVC film is reached, i.e. the minimum voltage that causes a portion of an insulator to become electrically conductive. XPS study indicates that the conducting phase created in the PVC film after energetic Cs+ bombardment consists of graphitized carbon and metallic cesium clusters. After the dielectric breakdown of the film, the positive charge, previously accumulated on the surface, is neutralized through the conductive regions, which are created in the insulating film. During Cs+ sputtering of a PVC film, the chemical structure of the analyzed surface is completely modified and some ionic bonds such as CsC and CsCl are also created.

  14. Respiratory illness caused by overheating of polyvinyl chloride.

    PubMed Central

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

    1982-01-01

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

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

    PubMed

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

    2014-05-14

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

  16. Electrospun chitosan/polyvinyl alcohol nanofibre mats for wound healing.

    PubMed

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2014-04-01

    Chitosan (CS) aqueous salt blended with polyvinyl alcohol (PVA) nanofibre mats was prepared by electrospinning. CS was dissolved with hydroxybenzotriazole (HOBt), thiamine pyrophosphate (TPP) and ethylenediaminetetraacetic acid (EDTA) in distilled water without the use of toxic or hazardous solvents. The CS aqueous salts were blended with PVA at different weight ratios, and the effect of the solution ratios was investigated. The morphologies and mechanical and swelling properties of the generated fibres were analysed. Indirect cytotoxicity studies indicated that the CS/PVA nanofibre mats were non-toxic to normal human fibroblast cells. The CS-HOBt/PVA and CS-EDTA/PVA nanofibre mats demonstrated satisfactory antibacterial activity against both gram-positive and gram-negative bacteria, and an in vivo wound healing test showed that the CS-EDTA/PVA nanofibre mats performed better than gauze in decreasing acute wound size during the first week after tissue damage. In conclusion, the biodegradable, biocompatible and antibacterial CS-EDTA/PVA nanofibre mats have potential for use as wound dressing materials. PMID:22925275

  17. Effects of bleeder cloth impressions on the use of polar backscatter to detect porosity

    NASA Technical Reports Server (NTRS)

    Handley, S. M.; Miller, J. G.; Madaras, Eric I.

    1988-01-01

    The influence of the nature of the composite's surface on ultrasonic polar backscatter measurements for detecting and characterizing porosity in composite laminates is studied, focusing on the effects of bleeder cloth impressions noted by Bar-Cohen (1987). The results indicate that the presence of the bleeder cloth impressions substantially influences the degree of anisotropy. It is found that, for relatively thin samples in which selective time gating is not feasible, the state of the insonified surface and the state of the back surface both influence the received signal.

  18. Investigation of Method for Changing Impression of Musical Piece by Changing its Tempo

    NASA Astrophysics Data System (ADS)

    Fukumoto, Makoto; Okamatsu, Keita; Matsuo, Kazuhisa

    We propose a simple method that changes impression of musical piece by changing its tempo and investigate psycho-physiological effects of the method with listening experiment. In the experiment, 8 subjects listened same musical pieces with various tempi, and analysis of heartbeat and Semantic-Differential method were used. In 6 out of 10 adjective pairs, inverted-U shapes were observed, and peak tempi of them were different. Moreover, “relaxed” evaluation might be related to listener's heart rate in rest. These results suggest possibility of constructing novel media player that changes impression of musical piece.

  19. Influence of impression of vehicle styling on loudness of acceleration sounds in cabin.

    PubMed

    Yoshida, Junji; Igata, Takumi

    2011-07-01

    The influence of participants' impressions of vehicle styling on the loudness of acceleration sounds was investigated. A series of images of luxury or sporty vehicles was presented to the participants as acceleration sounds were being replayed. The results indicated that participants who were frequent drivers felt that the sound associated with luxury vehicles was louder than that associated with sporty vehicles. However, participants who rarely drove perceived almost no difference between the loudness of the two vehicles types. Thus, the loudness was shown to depend on both the participants' impression of the vehicle and their driving frequency. PMID:21786863

  20. Rheological properties of polyvinylsiloxane impression materials before mixing and during setting related to handling characteristics

    NASA Astrophysics Data System (ADS)

    Lee, Hyang-Ok; Lee, In-Bog

    2012-09-01

    The purpose of this study is to determine and compare the handling and rheological properties of polyvinylsiloxane impression pastes before mixing and during setting, and to investigate the effect of its constituents on the properties of the materials. Five polyvinylsiloxane impression materials (Examixfine, Extrude, Honigum, Imprint II, and Express) were used. A flow test and a drip test were performed to determine the handling characteristics. The rheological properties of each impression material prior to mixing (shear stress, viscosity) and during setting (storage modulus G'), loss modulus G?), loss tangent tan?) were measured with a stress-controlled rheometer at 25°C and 32°C, respectively. Inorganic filler content of each impression material was measured and observed with a SEM. The molecular weight distribution of polymer matrix was determined with a gel permeation chromatography (GPC). Express and Honigum display lower flow compared to the other materials, due to their high yield-stress values. Examixfine exhibits the greatest flow. All materials display pseudoplastic behavior, excluding the Examixfine catalyst. The viscosities at low shear rate are greatest for Express and Honigum; however, under high shear conditions, the viscosities of Extrude and Honigum are the lowest. Following mixing, each material show an increase in G', finally reaching a plateau, and the tan? rapidly decreases with time. Imprint II shows the highest final G' as well as the most rapid decrease in tan?. Express and Imprint II present the highest filler content and rough filler surface, while Honigum shows the lowest filler content and small filler particles. Most products are composed of polymers over 30 kDa and oligomers less than 1 kDa. Each impression material possesses different rheological properties, which significantly affect the handling characteristics. The yield stress of the impression material minimizes unnecessary flow prior to and after seating. Viscoelastic change during setting of each impression material determines the setting time and the stiffness after setting. These rheological properties of impression materials are affected by the filler content and molecular weight distribution of polymer matrix.

  1. Case series of undetected intranasal impression material in patients with clefts.

    PubMed

    Jones, Simon D; Drake, David J

    2013-04-01

    We report the cases of two female patients in their twenties who had had corrective surgery for bilateral cleft lip and palate as babies. They had both had residual palatal fistulas and had had further treatment that required repeated dental impressions. Several years later both had complained of persistent nasal discomfort and discharge, and routine clinical examination and investigations had failed to identify the cause. Full examination of the whole nasal cavity under general anaesthesia, in both cases, showed the presence of displaced dental impression material in the nasal floor. Removal resulted in complete resolution of symptoms. PMID:22222222

  2. Applicants' preference for impression management tactic in employment interviews by Transportation Security Administration.

    PubMed

    Scudder, Joseph N; Lamude, Kevin G

    2009-04-01

    Following past findings on employment interviews, this study hypothesized applicants would have a preference for using self-promoting tactics of impression management over other focuses. Self-reports of impression management tactics were collected from 124 applicants who had interviews for screener positions with the Transportation Security Administration. Contrary to the hypothesis, analysis indicated participants reported they used more ingratiation tactics attempting to praise the interviewer than self-promotion tactics which focused on their own accomplishments. Special qualifications for security jobs which required well-developed perceptual abilities and the controlling structure of the interview context were perhaps responsible for present results differing from prior findings. PMID:19610468

  3. Integrated Modular Propulsion and Regenerative Electro-energy Storage System (IMPRESS) for small satellites

    SciTech Connect

    Mitlitsky, F. [Lawrence Livermore National Lab., CA (United States); de Groot, W. [Nyma, Inc., Brook Park, OH (United States); Butler, L.; McElroy, J. [United Technologies Corp., Windsor Locks, CT (United States). Hamilton Standard Div.

    1996-09-01

    The IMPRESS is a significant advancement in space system technology as it is able to operate alternately as a fuel cell to produce electrical power from stored hydrogen and oxygen and as a water electrolyzer using electrical power to produce hydrogen and oxygen from stored water. The electrolysis of a controllable fraction of stored water can provide high Isp rocket propellants on demand. The heart of the IMPRESS is the Unitized Regenerative Fuel Cell (URFC), which produces power and electrolytically regenerates its reactants using a single stack of reversible cells. This integrated approach has several significant advantages over separate (battery) power and propulsion systems.

  4. The detrimental effects of atypical nonverbal behavior on older adults' first impressions of individuals with Parkinson's disease.

    PubMed

    Hemmesch, Amanda R

    2014-09-01

    After viewing short video clips of individuals with Parkinson's disease (PD) who varied in the symptoms of facial masking (reduced expressivity) and abnormal bodily movement (ABM: including tremor and related movement disorders), older adult observers provided their first impressions of targets' social positivity. Impressions of targets with higher masking or ABM were more negative than impressions of targets with lower masking or ABM. Furthermore, masking was more detrimental for impressions of women and when observers considered emotional relationship goals, whereas ABM was more detrimental for instrumental relationship goals. This study demonstrated the stigmatizing effects of both reduced and excessive movement. PMID:25244472

  5. A systematic study of the effect of molecular weights of polyvinyl alcohol on polyvinyl alcohol-graphene oxide composite hydrogels.

    PubMed

    Xue, Rongrong; Xin, Xia; Wang, Lin; Shen, Jinglin; Ji, Fangrui; Li, Wenzhe; Jia, Chunyu; Xu, Guiying

    2015-02-21

    Polyvinyl alcohol (PVA) hydrogels have been proposed for use as promising biomaterials in biomedical and tissue engineering, and graphene oxide (GO) has been recognized as a unique two-dimensional building block for various graphene-based supramolecular architectures. In this article, we systematically studied the influence of three kinds of PVA with different molecular weights on the interaction between PVA and GO. Moreover, the effects of PVA on the gelation of GO were also investigated. The native PVA hydrogel, as well as PVA-GO hybrid hydrogels, have been thoroughly characterized by the phase behavior study and various techniques including field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and rheological measurements. It can be seen that with the increase of the molecular weight of PVA, the addition of GO can effectively promote the gelation of PVA which can be reflected by a decrease of the critical gel concentration (CGC) for PVA-GO hydrogels. Dye adsorption experiments indicate that the toxic dye, i.e., methylene blue (MB), was efficiently entrapped in the PVA-GO xerogels. It is also demonstrated that the gelation of PVA and GO composites can be promoted by different supramolecular interactions, including hydrogen bonding and electrostatic interaction. This work indicates that the PVA-GO composite is a good candidate for preparing "super" and "smart" hydrogels and will enable further studies on the supramolecular chemistry of PVA, graphene and its derivatives. PMID:25613714

  6. Characterization, liquid crystalline behavior, electrochemical and optoelectrical properties of new poly(azomethine)s and a poly(imide) with siloxane linkages

    NASA Astrophysics Data System (ADS)

    Iwan, Agnieszka; Schab-Balcerzak, Ewa; Pociecha, Damian; Krompiec, Michal; Grucela, Marzena; Bilski, Pawel; K?osowski, Mariusz; Janeczek, Henryk

    2011-11-01

    New siloxane-containing poly(azomethine)s and a six-membered poly(imide) have been developed from siloxane-containing diamine with four different dialdehydes and 3,4,9,10-perylenetetracarboxylic dianhydride, and their thermotropic behavior, optoelectrical and electrochemical properties were examined. Mesomorphic behavior of the polymers was investigated via differential scanning calorimetry (DSC), polarizing optical microscopy (POM) and X-ray diffraction (WAXRD, SAXRD) studies. The electrochemical behavior of poly(azomethine)s and poly(imide) was studied by differential pulse voltammetry (DPV). The HOMO levels of these polymers were in the range of -5.13 to -5.90 eV. UV-vis properties of the polymers were investigated in solid state as thin films and in chloroform solution. Optical energy band gap ( Egopt.) was calculated from absorption spectra and absorption coefficients ?. The photoluminescence properties (PL) of obtained polymers were studied in chloroform solution. The investigated poly(azomethine)s emitted blue light, while the poly(imide) emitted green light. The polymers were irradiated with a test dose of 1 Gy Co-60 gamma-rays to detect their thermoluminescence properties in the temperature range of 50-200 °C. Polymer monolayer (ITO/polymer/Al) and bulk heterojunction (BHJ) (ITO/polymer:PCBM/Al and ITO/PEDOT:PSS/polymer:PCBM/Al) devices were prepared with PAZ and PI used as active layers and I- U curves were measured in the dark and during irradiation with light (under illumination of 1000 W/m 2). Poly(azomethine)s were blended with [6,6]-phenyl C 61 butyric acid methyl ester (PCBM). Selected properties of the investigated polymers with siloxane linkages were compared with the polymers ( PAZ1a- PAZ3a, PIa) prepared from the same dialdehydes or dianhydride and poly(1,4-butanediol)bis(4-aminobenzoate).

  7. Polycarbonate-silsesquioxane and polycarbonate-siloxane nanocomposites: Synthesis, characterization, and application in the fabrication of porous inorganic films

    NASA Astrophysics Data System (ADS)

    Abdallah, Jassem

    Three types of poly(bicycle[2.2.1]heptane carbonate) or poly(norbornane carbonate) or PNC oligomers were synthesized and characterized via spectroscopic methods and elemental analyses to validate their chemical structures. End-group analyses were used to estimate the degree of polymerization of the oligomers via the use of proton nuclear magnetic resonance (1H NMR) results. Random-coil and rigid-rod models were used to estimate the sizes of individual PNC chains based on the degrees of polymerization calculated from NMR data. Due to the small sizes of the PNC chains, dynamic light scattering (DLS) was incapable of measuring the hydrodynamic radii, RH, of individual chains. Attempts at using gel permeation chromatography (GPC) data to estimate the hydrodynamic radii of individual chains consistently provided values that were an order of magnitude smaller than the estimated sizes of individual chains based on random-coil calculations. The thermal properties of PNCs were determined via differential scanning calorimetry (DSC) and thermogravimetric analyses (TGAs). All three types of PNC structures were both thermally-labile and acidolytically-labile, allowing them to be used as sacrificial materials in both direct-write and thermally-processed template systems. TGA data was used to determine the kinetic parameters for the thermolytic decomposition reactions and evolved-gas analysis via mass spectrometry (TGA-MS) was used to validate the mechanisms for polycarbonate thermolysis reactions that have been previously proposed in literature. PNC oligomers were freely-mixed with hydrogen silsesquioxane (HSQ) to form solutions that were spin-coated to form templated films. Ellipsometry and dielectric measurements were used to track the changes in the optical and dielectric properties of templated films and effective medium approximations were used to estimate the level of porosity incorporated within each porous film. Transmission electron microscopy (TEM) showed that the free-mixing of PNCs with HSQ resulted in the agglomeration of the porogen molecules during the spincoating step. This phase-segregation led to the formation of domains with dimensions much larger than those of the individual chains, and during decomposition large pores were produced. To combat the phase segregation, hydrosilylation reactions were used to covalently bond vinyl end-capped PNC chains to silane-functionalized siloxane and silsesquioxane molecules. These matrix-like materials served as compatibilizers in order to improve the phase-compatibility of the sacrificial polymers in HSQ films. NMR and GPC analyses showed that the solids recovered from the hydrosilylation reactions were binary mixtures of hybrid nanocomposite molecules and residual ungrafted chains. All attempts at isolating the hybrid molecules proved to be unsuccessful and the solids were templated as blends in HSQ films. TEM imaging showed that the domains in these nanocomposite films had bimodal size distributions due to the presence of two components in the mixtures. The hybrid molecules produced pores ranging in size from about 6-13 nm as a result of improvements in the phase-compatibility of the grafted oligomers. However, the residual ungrafted oligomers in the blends produced larger domains measuring 30-40 nm. Although the siloxane and silsesquioxane molecules were shown to fulfill the stated goal of compatibilizing the PNC chains with HSQ and the hybrid molecules produced domain sizes comparable to those of templated films reported in literature, the difficulty in isolating the hybrid molecules from the ungrafted oligomers limits the benefits of using these blends as porogen materials. It is believed that separation difficulties can be avoided if the physical and chemical conditions used in the vinyl termination reactions can be adjusted to ensure 100% conversion of all the terminal hydroxyl groups to vinyl groups. Doing so would allow all PNC chains to be grafted during hydrosilylation reaction; thus, avoiding the recovery of ungrafted oligomers. The recovery of pure hydrosilylation p

  8. Tough package, strong taste: The influence of packaging design on taste impressions and product evaluations

    Microsoft Academic Search

    Liza Becker; Thomas J. L. van Rompay; Hendrik N. J. Schifferstein; Mirjam Galetzka

    2011-01-01

    This study examines the influence of packaging design on taste impressions. Building forth on research addressing transfer effects of symbolic associations from one sense to another, in this study it was studied if, and to what extent, potency-related associations portrayed by shape curvature and color saturation of yoghurt packages transfer to subsequent taste experiences. Furthermore, the influence of participants’ sensitivity

  9. Coastal ImpressionsA Photographic Journey along Alaska's Gulf Coast Exhibit compiled by

    E-print Network

    i Coastal ImpressionsA Photographic Journey along Alaska's Gulf Coast #12;ii Exhibit compiled by Susan Saupe, Mandy Lindeberg, and Dr. G. Carl Schoch Photographs selected by Mandy Lindeberg and Susan at NOAA's Alaska Fisheries Science Center Auke Bay Laboratories and the Alaska Regional Office has taken

  10. Arctic ImpressionsA Photographic Journey along Alaska's Arctic Coast Exhibit compiled by

    E-print Network

    i Arctic ImpressionsA Photographic Journey along Alaska's Arctic Coast #12;ii Exhibit compiled by Mandy Lindeberg, Tahzay Jones, Catherine Coon, and John Harper Photographs selected by Mandy LindebergZone imagery and data. The staff at NOAA's Alaska Fisheries Science Center Auke Bay Laboratories and the Alaska

  11. 79Black Holes -Hot Stuff! Artist's impression of gas falling into a black hole

    E-print Network

    79Black Holes - Hot Stuff! Artist's impression of gas falling into a black hole Image credit: NASA / Dana Berry, SkyWorks Digital When gas flows into a black hole, it gets very hot and emits light. The gas is heated because the atoms collide with each other as they fall into the black hole. Far away

  12. OfficeMax ImPress is your printing services resource.

    E-print Network

    Miami, University of

    OfficeMax ImPress is your printing services resource. Whatever your printing needs, we can do it and printing services from OfficeMax ImPressTM at any of the nearly 900 OfficeMax retail locations. To take supplies and print services. Take your card to the OfficeMax ImPressTM counter. With your first purchase

  13. First impression of Watson and Crick, Erwin ChargaffSite: DNA Interactive (www.dnai.org)

    NSDL National Science Digital Library

    2008-10-06

    Interviewee: Erwin Chargaff DNAi Location:Code>finding the structure>players>Erwin Chargaff The meeting with Watson and Crick Erwin Chargaff reads a passage from his book Heraclitean Fire: Sketches from a Life Before Nature, describing his impressions of Crick and Watson.

  14. Organizational Impression Management Behaviors in Social Media: A Perspective of a Social Networking Site

    Microsoft Academic Search

    Kelsey H Terrell; Linchi Kwok

    2011-01-01

    In the macro-organizational level, Impression management (IM) is the study of how organizations attempt to manage or control the perceptions others form of them. Among the studies about organizational IM theory, relatively little discussion was framed under the social media settings. This proposed study is designed to use text mining and opinion mining techniques to answer two research questions: (1)

  15. Impression-oriented music courseware and its application in elementary schools

    Microsoft Academic Search

    Shiori Sasaki; Kiku Watagoshi; Kosuke Takano; Kazuo Hirashima; Yasushi Kiyoki

    2010-01-01

    Purpose – The purpose of this paper is to present the design and implementation of music courseware that features a music search system that uses impression keywords. The paper applies the courseware to Kansei (sensibility) development for elementary and junior high school students. The objectives of this courseware are to cultivate children's sensitivity to the mood of a music selection;

  16. Misleading First Impressions: Different for Different Facial Images of the Same Person.

    PubMed

    Todorov, Alexander; Porter, Jenny M

    2014-05-27

    Studies on first impressions from facial appearance have rapidly proliferated in the past decade. Almost all of these studies have relied on a single face image per target individual, and differences in impressions have been interpreted as originating in stable physiognomic differences between individuals. Here we show that images of the same individual can lead to different impressions, with within-individual image variance comparable to or exceeding between-individuals variance for a variety of social judgments (Experiment 1). We further show that preferences for images shift as a function of the context (e.g., selecting an image for online dating vs. a political campaign; Experiment 2), that preferences are predictably biased by the selection of the images (e.g., an image fitting a political campaign vs. a randomly selected image; Experiment 3), and that these biases are evident after extremely brief (40-ms) presentation of the images (Experiment 4). We discuss the implications of these findings for studies on the accuracy of first impressions. PMID:24866921

  17. Impressions: African American First-Year Students' Perceptions of a Predominantly White University.

    ERIC Educational Resources Information Center

    Douglas, Katie Branch

    1998-01-01

    Investigated African American college freshmen's impressions of a predominantly white university. Students took photographs illustrating their perceptions and discussed them individually and in groups. Six themes emerged: the campus' physical beauty and immensity; participants' consciousness of being black on campus; the influence of Greek-letter…

  18. Impressions of Personality Based on Body Forms: An Application of Hillestad's Model of Appearance

    Microsoft Academic Search

    Kim K. P. Johnson

    1990-01-01

    The purpose of this research was to investigate whether impressions ofpersonality varied by size and shape of male and female body forms. Three hundred eighty-five male and female undergraduates served as subjects. Each subject received a questionnaire with a line drawing attached. Each drawing was either a male or a female previously rated by judges as representing an ectomorphic (thin),

  19. A one-appointment impression and centric relation record technique for compromised complete denture patients

    Microsoft Academic Search

    Izharul Haque Ansari

    1997-01-01

    This article describes a two-in-one modified custom tray and record block system that is recommended for compromised elderly patients. Custom trays, which are made on primary casts and formed from a patient's functionally corrected old dentures, are used to make final impressions and centric jaw relation records in one clinical appointment. The clinical visits are reduced without compromising the quality

  20. Lifting the Curtain on the Wizard of Oz: Biased Voice-Based Impressions of Speaker Size

    ERIC Educational Resources Information Center

    Rendall, Drew; Vokey, John R.; Nemeth, Christie

    2007-01-01

    The consistent, but often wrong, impressions people form of the size of unseen speakers are not random but rather point to a consistent misattribution bias, one that the advertising, broadcasting, and entertainment industries also routinely exploit. The authors report 3 experiments examining the perceptual basis of this bias. The results indicate…

  1. When It Comes Round to Marking Assignments: How to Impress and How to "Distress" Lecturers ...

    ERIC Educational Resources Information Center

    Greasley, Pete; Cassidy, Andrea

    2010-01-01

    What do lecturers look for when marking essays? What impresses them and what frustrates them? In this paper, we present the results of a survey which asked lecturers to address these questions. Thirty-two lecturers responded to an email survey in which they listed the problems they found most frustrating when marking essays and the factors which…

  2. The International Space Station (ISS) is an impressive home away from home with a

    E-print Network

    Maranas, Costas

    1 The International Space Station (ISS) is an impressive home away from home with a structure the International Space Station. In addition, I will give an update on Commercial Crew Development and NASA's plan scientific and technical briefings, intensive instruction in space station systems, Extravehicular Activities

  3. Thermal spray anodes for impressed current cathodic protection of reinforced concrete structures

    Microsoft Academic Search

    B. S. Jr. Covino; S. D. Cramer; S. J. Bullard; G. R. Holcomb; W. K. Collins; G. E. McGill

    1999-01-01

    Differences between thermal spray Zn and catalyzed thermal spray Ti, used for impressed current cathodic protection of reinforced concrete structures, are reviewed. Considerations include spray parameters, atomizing gases, spray rate, and costs, as well as physical properties, composition, and structure. Comparisons of the effect of electrochemical aging on voltage requirements, bond strength, coating resistivity, water permeability, and anode-concrete interfacial chemistry

  4. Thermal spray anodes for impressed current cathodic protection of reinforced concrete structures

    SciTech Connect

    Covino, B.S. Jr.; Cramer, S.D.; Bullard, S.J.; Holcomb, G.R.; Collins, W.K. (Dept. of Energy, Albany, OR (United States). Albany Research Center); McGill, G.E. (Oregon Dept. of Transportation, OR (United States))

    1999-01-01

    Differences between thermal spray Zn and catalyzed thermal spray Ti, used for impressed current cathodic protection of reinforced concrete structures, are reviewed. Considerations include spray parameters, atomizing gases, spray rate, and costs, as well as physical properties, composition, and structure. Comparisons of the effect of electrochemical aging on voltage requirements, bond strength, coating resistivity, water permeability, and anode-concrete interfacial chemistry are included.

  5. On Being Consistent: The Role of Verbal–Nonverbal Consistency in First Impressions

    Microsoft Academic Search

    Max Weisbuch; Nalini Ambady; Asha L. Clarke; Shawn Achor; Jeremy Veenstra-Vander Weele

    2010-01-01

    Extant research suggests that people seem deceitful and difficult to understand when their verbal behavior is inconsistent with their nonverbal behavior. Building on this literature, we examined the impact of behavioral coherence on impression formation: We expected people to be likeable to the extent that their verbal and nonverbal behavior was consistent (i.e., coherent). In two studies, participants were videotaped

  6. Is Cleanliness Next to Godliness? The Role of Housekeeping in Impression Formation

    ERIC Educational Resources Information Center

    Harris, Paul B.; Sachau, Daniel

    2005-01-01

    We conducted a study to determine if the cleanliness of an apartment would affect observer impressions of the resident. Participants (210 female and 126 male undergraduate students) read a story in which a character's apartment was described as clean or dirty or in which no information about housekeeping was provided. For each condition, half the…

  7. The Effects of Interior Design on Communication and Impressions of a Counselor in a Counseling Room

    ERIC Educational Resources Information Center

    Miwa, Yoshiko; Hanyu, Kazunori

    2006-01-01

    This study aimed to investigate effects of the interior design of a counseling room on participants' self-disclosure and impressions of a counselor. The authors examined the effects of lighting and decorations. It tested four conditions crossing decorations (with or without home-like decorations) and type of lighting (bright or dim). Eighty…

  8. A Test of an Impression Management Interpretation of Public Responses to Positive Inequity.

    ERIC Educational Resources Information Center

    Rivera, Alba N.; Tedeschi, James T.

    Recent evidence indicates that subjects experience "distress" when they are beneficiaries of an inequitable distribution of rewards in a dyad. Yet, reinforcement theory postulates that individuals should experience more pleasure, the greater the reward they receive. An impression management hypothesis would reconcile these apparently opposing…

  9. Background music genre can modulate flavor pleasantness and overall impression of food stimuli.

    PubMed

    Fiegel, Alexandra; Meullenet, Jean-François; Harrington, Robert J; Humble, Rachel; Seo, Han-Seok

    2014-05-01

    This study aimed to determine whether background music genre can alter food perception and acceptance, but also to determine how the effect of background music can vary as a function of type of food (emotional versus non-emotional foods) and source of music performer (single versus multiple performers). The music piece was edited into four genres: classical, jazz, hip-hop, and rock, by either a single or multiple performers. Following consumption of emotional (milk chocolate) or non-emotional food (bell peppers) with the four musical stimuli, participants were asked to rate sensory perception and impression of food stimuli. Participants liked food stimuli significantly more while listening to the jazz stimulus than the hip-hop stimulus. Further, the influence of background music on overall impression was present in the emotional food, but not in the non-emotional food. In addition, flavor pleasantness and overall impression of food stimuli differed between music genres arranged by a single performer, but not between those by multiple performers. In conclusion, our findings demonstrate that music genre can alter flavor pleasantness and overall impression of food stimuli. Furthermore, the influence of music genre on food acceptance varies as a function of the type of served food and the source of music performer. PMID:24530691

  10. MDSC study of melting and glass transitions in elastomeric dental impression materials

    Microsoft Academic Search

    J. M. Vickery; W. A. Brantley; T. A. Bardin

    2001-01-01

    A modulated differential scanning calorimetric (MDSC) study was performed to investigate melting and glass transitions in vinyl polysiloxane, polyether and polysulfide dental elastomeric impression materials. The MDSC analyses were performed from ?150 to 200°C, using heating-only modulation conditions and sufficient modulations to define the transitions. The two vinyl polysiloxane materials had a single melting peak near ?50°C, whereas the polyether

  11. Variation in individual walking behavior creates the impression of a Lvy flight

    E-print Network

    Variation in individual walking behavior creates the impression of a Lévy flight Sergei Petrovskiia in the distribution of movement lengths. Such distributions occur if individuals move according to a Lévy flight (a to display superdiffusive characteristics, often interpreted as being characteristic for a Lévy flight

  12. Impression-Oriented Music Courseware and Its Application in Elementary Schools

    ERIC Educational Resources Information Center

    Sasaki, Shiori; Watagoshi, Kiku; Takano, Kosuke; Hirashima, Kazuo; Kiyoki, Yasushi

    2010-01-01

    Purpose: The purpose of this paper is to present the design and implementation of music courseware that features a music search system that uses impression keywords. The paper applies the courseware to "Kansei" (sensibility) development for elementary and junior high school students. The objectives of this courseware are to cultivate children's…

  13. Adolescents' Impressions of Antismoking Media Literacy Education: Qualitative Results from a Randomized Controlled Trial

    ERIC Educational Resources Information Center

    Primack, Brian A.; Fine, Danielle; Yang, Christopher K.; Wickett, Dustin; Zickmund, Susan

    2009-01-01

    Although media literacy represents an innovative venue for school-based antismoking programming, studies have not systematically compared student impressions of these and traditional programs. This study utilized data from a randomized trial comparing these two types of programs. After each program, students responded to three open-ended questions…

  14. Predicting Users' First Impressions of Website Aesthetics With a Quantification of

    E-print Network

    Chen, Yiling

    Predicting Users' First Impressions of Website Aesthetics With a Quantification of Perceived Visual of aesthetics based on perceptual models of a website's colorfulness and visual complexity. In an online study of the variance in the ratings of aesthetic appeal given after viewing a website for 500ms only. Author Keywords

  15. A Second Chance to Make a First Impression: Factors Affecting the Longevity of Online Dating Relationships

    Microsoft Academic Search

    Lindsay Shaw Taylor; Andrew T. Fiore; G. A. Mendelsohn; Coye Cheshire

    2010-01-01

    This research explored the transition of romantic relation- ships from meeting online to the first face-to-face date. It is inevitable that impressions of a partner will change to some degree, but how much, and with what consequences? One hundred and fifty users of a popular online dating site parti- cipated in the study. They recalled a person whom they had

  16. Impressions of the Prison Rape Elimination Act: Wardens' Attitudes Toward, and Implementations of, the PREA

    E-print Network

    New Hampshire, University of

    Impressions of the Prison Rape Elimination Act: Wardens' Attitudes Toward, and Implementations of, the PREA Bethany Schmidt #12;Prison Rape Elimination Act (2003) Establish a zero-tolerance policy Prison rape as a top priority Increase available data through increased recording Develop national standards

  17. First Impressions on the State of Cellular Data Connectivity in India

    E-print Network

    Ribeiro, Vinay

    First Impressions on the State of Cellular Data Connectivity in India Zahir Koradia Goutham Mannava Triukose Dept. of Comp Sc IIT Bombay Mumbai, India Dept. of Comp Sc IIT Delhi§ New Delhi, India National ICT Australia Sydney, Australia ABSTRACT Cellular penetration in India has grown tremendously in re

  18. An Exploratory Investigation Examining Male and Female Students' Initial Impressions and Expectancies of Lecturers

    ERIC Educational Resources Information Center

    Batten, John; Birch, Phil David John; Wright, James; Manley, Andrew John; Smith, Matt Jeffrey

    2014-01-01

    The aim of this study was to examine the informational cues that male and female students perceive to be influential when developing initial impressions and expectancies of a lecturer. University students ("n" = 752) rated the extent to which 30 informational cues influence their initial perceptions of a lecturer. Following exploratory…

  19. Fabrication and characterization of ophthalmically compatible hydrogels composed of poly(dimethyl siloxane-urethane)/Pluronic F127.

    PubMed

    Lin, Chien-Hong; Lin, Wen-Ching; Yang, Ming-Chien

    2009-06-01

    The novel poly(dimethyl siloxane-urethane)/Pluronic hydrogel was fabricated to develop a new ophthalmically compatible material. In this study, the soft segment consists of poly(dimethylsiloxane) dialkanol having hydroxyethyl propoxy end groups and hard segment consists of isophorone diisocyanate (IPDI). The poly(ethylene glycol) methacrylate (PEGMA) was added as the chain-extender to form UV-curable silicone marcomer. Finally, the semi-interpenetrating network (semi-IPN) hydrogel was achieved by reacting with silicone marcomer and Pluronic F127 triblock copolymer under UV-photopolymerization (mSi-PU/F127). It was found that the increase in Pluronic F127 content led to decreased water contact angle and increased the water content of silicone hydrogels. Elastic modulus also decreased with Pluronic F127 content, while surface roughness did not significantly differ from silicone controls. The Pluronic F127 content reached 4%, the apparent protein adsorption amount decreased about 60% in comparison with that of mSi-PU control. It indicated that the mSi-PU/F127 hydrogel membrane had an excellent ability to resist protein adsorption. Additionally, the oxygen permeability (Dk) would decrease 24%, as compared with mSi-PU control. Furthermore, these hydrogel membranes were regarded as non-cytotoxic through in vitro L929 fibroblasts proliferation assay. Overall results demonstrated that the mSi-PU/F127 semi-IPN hydrogel provided silicone hydrogel materials not only having relatively high oxygen permeability and a relatively low modulus, but also enhancing hydrophilicity and anti-protein adsorption. PMID:19188049

  20. Next generation siloxane-based Bottom Anti-Reflective Coating (BARC) formulations with selective strip rates and required optical properties

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, Sudip; Kennedy, Joseph; Pandey, Yamini; Amin, Preeti; Gill, Jaswinder

    2009-03-01

    Bottom Anti Reflective Coating (BARC) materials are generally used to minimize reflection of incident light from the substrate (Rsub). As IC manufactures move to high NA systems to meet the patterning requirements for next generation technology as well as the use of new lower dielectric constant materials in the back-end-of-line dielectric, the requirements for developing BARC materials with new properties such as faster strip rate and properly tuned optical properties (n = refractive index and k=extinction coefficient) are essential. Some photoresist patterning schemes may also require a dual BARC system such as tri-layer patterning (TLP), which is undergoing extensive evaluation in academia and industries. This work focuses on Honeywell's next generation DUO193 material (DUO193FS), which is a siloxane-based polymer with an organic 193 nm chromophore attached to it. The effects of additives for adjusting strip rate in a wet chemical stripper, while maintaining chemical resistance to a photoresist developer, 2.38% TMAH in water are discussed. Different spectroscopic studies are performed to elucidate the mechanism of faster strip rate. Solvation of silanol groups and their orientation in the presence of additives are found to be secondary mechanism. The primary reason for enhanced strip rate is attributed to the addition of additives A and B, which lower bulk density of the solid film. DUO193FS can be stand alone BARC or used with another BARC as part of a dual BARC system to further minimize Rsub, maintaining resistance to 2.38% TMAH, planarizing any underlying topography and keeping the final film strip rate high.

  1. Studies on silicon NMR characterization and kinetic modeling of the structural evolution of siloxane-based materials and their applications in drug delivery and adsorption

    NASA Astrophysics Data System (ADS)

    Ambati, Jyothirmai

    This dissertation presents studies of the synthetic processes and applications of siloxane-based materials. Kinetic investigations of bridged organoalkoxysilanes that are precursors to organic-inorganic hybrid polysilsesquioxanes are a primary focus. Quick gelation despite extensive cyclization is found during the polymerization of bridged silane precursors except for silanes with certain short bridges. This work is an attempt to characterize and understand some of the distinct features of bridged silanes using experimental characterization, kinetic modeling and simulation. In addition to this, the dissertation shows how the properties of siloxane-materials can be engineered for drug delivery and adsorption. The phase behavior of polymerizing mixtures is first investigated to identify the solutions that favor kinetic characterization. Microphase separation is found to cause gradual loss of NMR signal for certain initial compositions. Distortionless Enhancement by Polarization Transfer 29Si NMR is employed to identify the products of polymerization of some short-bridged silanes under no signal loss conditions. This technique requires knowing indirect 29Si-1H scalar coupling constants which sometimes cannot be measured due to second-order effects. However, the B3LYP density functional method with 6-31G basis set is found to predict accurate 29Si- 1H coupling constants of organoalkoxysilanes and siloxanes. The scalar coupling constants thus estimated are employed to resolve non-trivial coupled NMR spectra and quantitative kinetic modeling is performed using the DEPT Si NMR transients. In order to investigate the role of the organic bridging group, the structural evolution of bridged and non-bridged silanes are compared using Monte Carlo simulations. Kinetic and simulation models suggest that cyclization plays a key role right from the onset of polymerization for bridged silanes even more than in non-bridged silanes. The simulations indicate that the carbosiloxane rings formed from short-bridged precursors slow down but do not prevent gelation. The tuning of siloxane-based materials for adsorption technologies are also discussed here. In the first example, antioxidant enzyme loading is investigated as a means to reduce oxidative stress generated by silica nanoparticle drug carriers. Materials are engineered for promising enzyme loading and protection from proteolysis. Second, the potential of copper sulfate impregnation to enhance adsorption of ammonia by silica is explored by molecular simulation. KEYWORDS: Sol-gel Polymerization, Kinetic Investigation, Si NMR, Bridged Silanes, DFT Calculations.

  2. Carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing.

    PubMed

    Zhang, Di; Zhou, Wei; Wei, Bing; Wang, Xin; Tang, Rupei; Nie, Jiemin; Wang, Jun

    2015-07-10

    The objective of this study was to develop a novel carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing. To prepare the crosslinked hydrogels, poly(vinyl alcohol) (PVA) was grafted with succinate acid to yield carboxyl-modified poly(vinyl alcohol) (PVA-COOH). Hydrogel films based on PVA-COOH and chitosan (CS) at different concentrations were crosslinked through the formation of amide linkages. The mechanical properties of these crosslinked hydrogel films in dry and swollen state were greatly improved with high swelling ratio. Water vapor and oxygen permeability evaluations indicated that crosslinked hydrogel films could maintain a moist environment over wound bed. Biocompatibility test showed the crosslinked hydrogels had no cytotoxicity and hemolytic potential. Gentamicin sulfate-loaded crosslinked hydrogel films showed sustained drug release profile, and could effectively suppress bacterial proliferation and protect wound from infection. PMID:25857974

  3. Marginal and Internal Fit of Cobalt-Chromium Fixed Dental Prostheses Generated from Digital and Conventional Impressions

    PubMed Central

    Skjerven, Henrik; Carlsson, Pablo; Karlsson, Stig; Örtorp, Anders

    2014-01-01

    Objectives. Digital impressions are increasingly used and have the potential to avoid the problem of inaccurate impressions. Only a few studies to verify the accuracy of digital impressions have been performed. The purpose of this study was to compare the marginal and internal fit of 3-unit tooth supported fixed dental prostheses (FDPs) fabricated from digital and conventional impressions. Methods. Ten FDPs were produced from digital impressions using the iTero system and 10 FDPs were produced using vinyl polysiloxane (VPS) impression material. A triple-scan protocol and CAD software were used for measuring and calculating discrepancies of the FDPs at 3 standard areas: mean internal discrepancy, absolute marginal gap, and cervical area discrepancy. The Mann-Whitney U test was used for analyzing the results. Results. For conventional and digital impressions, respectively, FDPs had an absolute marginal gap of 147??m and 142??m, cervical area discrepancy of 69??m and 44??m, and mean internal discrepancy of 117??m and 93??m. The differences were statistically significant in the cervical and internal areas (P < 0.001). Significance. The results indicated that the digital impression technique is more exact and can generate 3-unit FDPs with a significantly closer fit compared to the VPS technique. PMID:24723954

  4. Good Soldiers and Good Actors: Prosocial and Impression Management Motives as Interactive Predictors of Affiliative Citizenship Behaviors

    Microsoft Academic Search

    Adam M. Grant; David M. Mayer

    2009-01-01

    Researchers have discovered inconsistent relationships between prosocial motives and citizenship behaviors. We draw on impression management theory to propose that impression management motives strengthen the association between prosocial motives and affiliative citizenship by encouraging employees to express citizenship in ways that both \\

  5. Semicrystalline poly(vinyl alcohol) films and their blends with poly(acrylic acid) and poly(ethylene glycol)

    E-print Network

    Peppas, Nicholas A.

    291 Semicrystalline poly(vinyl alcohol) films and their blends with poly(acrylic acid) and poly@che.utexas.edu Semicrystalline films of poly(vinyl alcohol) (PVA) were prepared by annealing amorphous PVA films at temperatures, which stabilized the films and made them behave as if they were chemically cross-linked. Films were

  6. A survey of the methods of disinfection of dental impressions used in dental hospitals in the United Kingdom.

    PubMed

    Blair, F M; Wassell, R W

    1996-05-25

    The potential for cross-infection from microbial contaminated dental impressions has long been recognised. This study set out to investigate impression decontamination procedures currently used in UK dental hospitals (1995) and to see how these may have changed since a previous survey, carried out in 1988. A variety of disinfection solutions and regimes were highlighted both within and between dental hospitals. Several of the disinfecting solutions currently being used have not been specifically tested for efficacy with impression materials. The laboratories were asked to highlight any adverse reactions. Five laboratories reported that some alginates resulted in casts with poor surface properties when immersed in hypochlorite (0.1 and 1%), sodium dichloroisocyanurate, and 2% glutaraldehyde solutions. This paper highlights that there is no universally recognised impression disinfection/sterilisation protocol. It is recommended that all impressions should at least undergo a disinfecting procedure by immersion in 1% sodium hypochlorite for a minimum of 10 minutes. PMID:8652299

  7. Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel cells with different solution conductivities

    E-print Network

    Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel, PA 16802, USA h i g h l i g h t s Polyvinyl alcohol (PVA) separators were prepared with spray Polyvinyl alcohol a b s t r a c t Separators are used to protect cathodes from biofouling and to avoid

  8. Structural and electronic properties of poly(vinyl alcohol) using density functional theory

    SciTech Connect

    Dabhi, Shweta, E-mail: shwetadabhi1190@gmail.com; Jha, Prafulla K., E-mail: shwetadabhi1190@gmail.com [Department of Physics, Maharaja Krishnakumasinhji Bhavnagar University, Bhavnagar-364001 (India)

    2014-04-24

    The first principles calculations have been carried out to investigate the structural, electronic band structure density of states along with the projected density of states for poly(vinyl alcohol). Our structural calculation suggests that the poly(vinyl alcohol) exhibits monoclinic structure. The calculated structural lattice parameters are in excellent agreement with available experimental values. The band structure calculations reveal that the direct and indirect band gaps are 5.55 eV and 5.363 eV respectively in accordance with experimental values.

  9. Lasting Impression

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2006-01-01

    Many schools and universities thought they were getting a good deal when they were building education facilities in the 1950s and 1960s. However, the K-12 and higher-education spaces constructed to accommodate the millions of baby-boomer students no longer look like the quick-fix bargain they did years ago. Low-quality materials and construction,…

  10. Good Impressions

    ERIC Educational Resources Information Center

    Renner, Jason

    2010-01-01

    It's a fact that most students, faculty and visitors who enter a school or college building eventually will use that facility's restrooms. Whether the destination is a lecture hall or classroom, the gym or other sports facility, the cafeteria or the student union, the human flow of restroom traffic is steady--year-round for some facilities and 24…

  11. Lasting Impressions

    ERIC Educational Resources Information Center

    Cottle, Thomas J.

    2004-01-01

    In this article, the author discusses how the matter of civil rights, and in particular the treatment of black people at the hands of white people, was conveyed to him most powerfully by three men of Harvard. The first was his high school headmaster, Herbert W. Smith, who introduced their class to the horrors of apartheid through the writings of…

  12. Modern Impressions

    ERIC Educational Resources Information Center

    Simkus, Joyce

    2010-01-01

    Claude Monet and the Impressionists were the forward thinkers and painters of their time. They used quick brushstrokes and a rapid pace to capture lively outdoor scenes. Inspired by the colors and shadows revealed by sunlight, the Impressionists typically worked outside, without many preliminary sketches or drafts. This was in direct contrast to…

  13. Unique Impressions

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2008-01-01

    For much of the 20th century, it was the engine that powered one of nation's most massive retail operations. By the beginning of the 21st century, the historic building was no longer needed to supply energy to what remained of the once bustling Sears, Roebuck and Co. campus on the West Side of Chicago. The original purpose of the Power House, as…

  14. Release characteristics of diclofenac sodium from poly(vinyl alcohol)\\/sodium alginate and poly(vinyl alcohol)-grafted-poly(acrylamide)\\/sodium alginate blend beads

    Microsoft Academic Search

    Oya ?anl?; Nuran Ay; Nuran I??klan

    2007-01-01

    In this study, acrylamide (AAm) was grafted onto poly(vinyl alcohol) (PVA) with UV radiation at ambient temperature. The graft copolymer (PVA-g-PAAm) was characterized by using Fourier transform infrared spectroscopy (FTIR), elemental analysis and differential scanning calorimetry (DSC). Polymeric blend beads of PVA-g-PAAm and PVA with sodium alginate (NaAlg) were prepared by cross-linking with glutaraldehyde (GA) and used to deliver a

  15. [Evaluation of cervical discrepancy of gold crowns in stone dies from various impression materials].

    PubMed

    Mantovani, A V; Stephano, C B; Roselino, R F; Roselino, R B; Campos, G M

    1990-01-01

    A stainless steel master die simulating a dental preparation for crown was used to make 3 gold castings from wax patterns obtained in 3 different ways: a) directly from the naked master die; b) from the same master die with a copper coping 30 microns thick; and c) with a similar copper coping, but 40 microns thick. The discrepancies of fit of the 3 master gold crowns were evaluated in 99 stones dies (33 for each casting) obtained from 11 different elastomeric impression materials (3 replicae of each). The results showed that: 1) stone dies with no coping presented a medium discrepancy of 284 microns, inadequate for clinical use; 2) the 30 microns and 40 microns copings presented medium discrepancies of 18 and 9 microns respectively, both suitable for clinical use. Thus, the use of copings tend to equalize the cervical discrepancy of fit of gold crowns, whatever be the elastomeric impression material used. PMID:2135328

  16. The effects of meal size and body size on individuals' impressions of males and females.

    PubMed

    Martins, Yolanda; Pliner, Patricia; Lee, Corrie

    2004-05-01

    Male and female participants provided impression ratings for either a normal-weight or overweight male or female target, who was portrayed as eating either small or large meals. Males rated normal-weight targets as more physically attractive than overweight targets, whereas ratings of physical attractiveness were unaffected by the body size manipulation among female participants. In addition, among male targets, the overweight large eater was rated the least socially attractive. For female targets, males rated the normal-weight large eater as the most socially attractive, whereas females rated the normal-weight small eater as the most socially attractive. Results are discussed in terms of how body and meal sizes interact to affect impressions of others. PMID:15093782

  17. Craniocervical growth collision: another explanation of the Arnold-Chiari malformation and of basilar impression

    Microsoft Academic Search

    M. Roth

    1986-01-01

    Analysis of neuro-cranio-spinal development suggests a cranio-cervical growth conflict as the cause of the Arnold-Chiari malformation and of basilar impression. The ascending course and elongation of the upper cervical nerves associated with the Arnold-Chiari malformation reflects the abnormal, caudo-cranially proceeding growth of the cervical spine. This is the opposite of the normal cranio-caudal direction of growth (which includes the brain)

  18. In vivo Study of the Accuracy of Dual-arch Impressions

    PubMed Central

    de Lima, Luciana Martinelli Santayana; Borges, Gilberto Antonio; Junior, Luiz Henrique Burnett; Spohr, Ana Maria

    2014-01-01

    Background: This study evaluated in vivo the accuracy of metal (Smart®) and plastic (Triple Tray®) dual-arch trays used with vinyl polysiloxane (Flexitime®), in the putty/wash viscosity, as well as polyether (Impregum Soft®) in the regular viscosity. Materials and Methods: In one patient, an implant-level transfer was screwed on an implant in the mandibular right first molar, serving as a pattern. Ten impressions were made with each tray and impression material. The impressions were poured with Type IV gypsum. The width and height of the pattern and casts were measured in a profile projector (Nikon). The results were submitted to Student’s t-test for one sample (? = 0.05). Results: For the width distance, the plastic dual-arch trays with vinyl polysiloxane (4.513 mm) and with polyether (4.531 mm) were statistically wider than the pattern (4.489 mm). The metal dual-arch tray with vinyl polysiloxane (4.504 mm) and with polyether (4.500 mm) did not differ statistically from the pattern. For the height distance, only the metal dual-arch tray with polyether (2.253 mm) differed statistically from the pattern (2.310 mm). Conclusion: The metal dual-arch tray with vinyl polysiloxane, in the putty/wash viscosities, reproduced casts with less distortion in comparison with the same technique with the plastic dual-arch tray. The plastic or metal dual-arch trays with polyether reproduced cast with greater distortion. How to cite the article: Santayana de Lima LM, Borges GA, Burnett LH Jr, Spohr AM. In vivo study of the accuracy of dual-arch impressions. J Int Oral Health 2014;6(3):50-5. PMID:25083032

  19. Impression Management and Self-Deceptive Enhancement among Hispanic and Non-Hispanic White Navy Recruits

    Microsoft Academic Search

    Stephanie Booth-Kewley; Paul Rosenfeld; Jack E. Edwards

    1992-01-01

    As part of a larger investigation of response effects on organizational surveys, the present study compared the responses of Hispanic and non-Hispanic U.S. Navy recruits on the Balanced Inventory of Desirable Responding (BIDR). The inventory contains two measures of socially desirable responding: impression management, the deliberate tendency to over-report desirable behaviors and under-report undesirable ones, and self-deceptive enhancement, the tendency

  20. What Elements of an Online Social Networking Profile Predict Target-Rater Agreement in Personality Impressions?

    Microsoft Academic Search

    David C. Evans; Samuel D. Gosling; Anthony Carroll

    2008-01-01

    Social-Networking Websites (SNWs) like Facebook and MySpace are playing an increasingly prevalent role in everyday social interactions. But very little is known about the effectiveness of the various profile elements in conveying information about the personality of the profile owner. Here we examine 5,303 impressions made on the basis of a specially designed social networking website (http:\\/\\/www.YouJustGetMe.com) and on the

  1. A calculation model for cathodic protection of underground extensive structures using impressed current cable anodes

    Microsoft Academic Search

    W. Machczyñski

    2002-01-01

    Proper design of cathodic protection by use of impressed current cable anodes requires the knowledge of current and potential\\u000a distribution along the anode and the structure to be protected. The conductive coupling between these earth-return circuits\\u000a results in different current and potential distributions along both structures when comparing with the case of separate anode.\\u000a In the paper calculation models –

  2. Responses on computer surveys: Impression management, social desirability, and the big brother syndrome

    Microsoft Academic Search

    Marle D. Thomas

    1996-01-01

    The quality of responses on computer and paper surveys was examined using 247 Navy recruits randomly assigned to a 2 (anonymous\\/identified) × 3 (administration modes: paper, computer-nonlinked, computer-linked) design. The computer-linked condition was included to simulate the ‘Big Brother Syndrome’ alluded to but not studied in past research. Higher levels of impression management were found in the identified computer-linked condition.

  3. Accuracy assessment of high frequency 3D ultrasound for digital impression-taking of prepared teeth

    NASA Astrophysics Data System (ADS)

    Heger, Stefan; Vollborn, Thorsten; Tinschert, Joachim; Wolfart, Stefan; Radermacher, Klaus

    2013-03-01

    Silicone based impression-taking of prepared teeth followed by plaster casting is well-established but potentially less reliable, error-prone and inefficient, particularly in combination with emerging techniques like computer aided design and manufacturing (CAD/CAM) of dental prosthesis. Intra-oral optical scanners for digital impression-taking have been introduced but until now some drawbacks still exist. Because optical waves can hardly penetrate liquids or soft-tissues, sub-gingival preparations still need to be uncovered invasively prior to scanning. High frequency ultrasound (HFUS) based micro-scanning has been recently investigated as an alternative to optical intra-oral scanning. Ultrasound is less sensitive against oral fluids and in principal able to penetrate gingiva without invasively exposing of sub-gingival preparations. Nevertheless, spatial resolution as well as digitization accuracy of an ultrasound based micro-scanning system remains a critical parameter because the ultrasound wavelength in water-like media such as gingiva is typically smaller than that of optical waves. In this contribution, the in-vitro accuracy of ultrasound based micro-scanning for tooth geometry reconstruction is being investigated and compared to its extra-oral optical counterpart. In order to increase the spatial resolution of the system, 2nd harmonic frequencies from a mechanically driven focused single element transducer were separated and corresponding 3D surface models were calculated for both fundamentals and 2nd harmonics. Measurements on phantoms, model teeth and human teeth were carried out for evaluation of spatial resolution and surface detection accuracy. Comparison of optical and ultrasound digital impression taking indicate that, in terms of accuracy, ultrasound based tooth digitization can be an alternative for optical impression-taking.

  4. Gordon and Mike's ICT Podcast: Apple iPad First Impression Podcast

    NSDL National Science Digital Library

    Qaissaunee, Michael

    Gordon and Mike's ICT Podcast offers perspectives on the information and communication technologies (ICT) industries from Gordon Snyder and Mike Qaissaunee. In this podcast, Mike discusses the technical specifications of the iPad â?? size, screen features, capacity, processor, and software details. He also gives his initial impressions on the impact this electronic device will have now and in the future. The running time for the show is 36:40.

  5. Effect of bite tray impression technique on relocation accuracy in frameless stereotactic radiotherapy

    SciTech Connect

    Herbert, Clare E.; Ebert, Martin A.; Barclay, D.; Whittall, David S.; Joseph, David J.; Harper, Chris S.; Spry, Nigel A

    2003-03-31

    A previously developed method for achieving patient relocation in fractionated stereotactic radiotherapy (attachment of an infrared fiducial system to a bite tray) relies on the integrity of a bite tray system that incorporates moulding to the patient's upper dentition. Reproducible and accurate patient positioning requires stability of the bite tray and mould during the full treatment process, both during the time the bite tray is inserted in the patient's mouth, and between separate bite tray insertions. The optimum construction method for a stable reproducible tray has not been sufficiently investigated. We undertook a study to identify factors which might influence the integrity of the hard palate bite tray system. Reprosil Fast Set Putty was used to construct 3 impression conditions; teeth only; teeth and alveolar sulcus; and teeth, alveolar sulcus, and the hard palate. Reproducibility was assessed by volunteers inserting the impressions multiple times and recording the locations of 8 standard reference points. Our results showed the optimal impression technique (i.e., the one that led to the smallest ranges in positional and rotational errors) was that which incorporated the teeth, alveolar sulcus, and hard palate.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. Influence of smoke from the combustion of polyvinyl chloride insulation on northern hardwood forest species

    Microsoft Academic Search

    Wood

    1968-01-01

    Open burning is often used as a method of removing insulation from wire in salvage operations. Forest communities in the vicinity of an open burning site in northern Pennsylvania where polyvinyl chloride (PVC) insulation was being burned from copper wire were examined. Chlorotic flecks of the upper leaf surface, red-brown to black necrotic spots on the leaves, defoliation, and death

  9. Effects of adding nano-clay on performance of polyvinyl acetate (PVA) as a wood adhesive

    Microsoft Academic Search

    Alireza Kaboorani; Bernard Riedl

    2011-01-01

    Polyvinyl acetate (PVA), a thermoplastic polymer, has poor performance at elevated temperatures and humid conditions as a wood adhesive. Two types of hydrophilic nano-clay were mixed at different loadings (1%, 2% and 4%) with PVA to improve the performance of PVA towards water and elevated temperatures. The properties of PVA-clay nanocomposites were characterized by measuring the shear strength of wood

  10. Tensile and thermal properties of nanocellulose-reinforced poly(vinyl alcohol) nanocomposites

    Microsoft Academic Search

    Mi-Jung Cho; Byung-Dae Park

    2011-01-01

    This work reports on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) nanocomposites reinforced with nanocelluloses isolated by the sulfuric acid hydrolysis using commercial microcrystalline cellulose (MCC). Nanocellulose-reinforced PVA nanocomposite films were prepared by the casting method with different nanocellulose loadings, which were exposed to tensile test, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The nanocellulose obtained by

  11. Polyvinyl pyridine metal complex as permanent antimicrobial finishing for viscose fabric

    Microsoft Academic Search

    A. Kantouch; A. Atef El-Sayed

    2008-01-01

    Viscose fabrics were treated with polyvinyl pyridine (PVP) using padding technique, followed by oxidation with hydrogen peroxide or peracetic acid, which was prepared by the reaction of tetra acetyl ethylene diamine (TAED) with hydrogen peroxide.Peracetic acid gives higher oxidation of PVP than hydrogen peroxide. FTIR study proved the formation of N-oxide as a result of oxidation. Incorporation of copper and

  12. Linear Dichroism of Cyanine Dyes in Stretched Polyvinyl Alcohol Films: A Physical Chemistry Laboratory Experiment.

    ERIC Educational Resources Information Center

    Natarajan, L. V.; And Others

    1983-01-01

    Provides background information, procedures, and results of an undergraduate physical chemistry experiment on the polarization of absorption spectra of cyanine dyes in stretched polyvinyl alcohol films. The experiment gives a simple demonstration of the concept of linear dichromism and the validity of the TEM method used in the analyses. (JN)

  13. Note and Record A note on polyvinyl chloride (PVC) pipe traps for

    E-print Network

    Pretoria, University of

    Note and Record A note on polyvinyl chloride (PVC) pipe traps for sampling vegetation of traditional traps, and many are furtive (Myers et al., 2007; Pittman et al., 2008). PVC pipe traps, which and Hyperolius (see Channing, 2001; du Preez & Carruthers, 2009), may be attracted to artificial refugia of PVC

  14. ORIGINAL PAPER Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect

    E-print Network

    Science+Business Media, LLC 2008 Abstract Poly(vinyl chloride) (PVC) and natural fiber composites were of the composites. The addition of fiber to PVC matrix increased glass transi- tion temperature (Tg), but lowered, PVC/rice husk compos- ites presented relatively smaller water absorption (WA) and thickness swelling

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  16. Potassium Iodide in Coloring of Polyvinyl Alcohol Film in Oxidizing Solution

    Microsoft Academic Search

    N. G. Ariko; V. E. Agabekov

    2003-01-01

    Conversion of potassium iodide in polyvinyl alcohol film by its treatment in the (NH4)2S2O8- CuSO4-KI-KCl-H2SO4-H2O oxidizing solution, leading to coloring of the film with molecular iodine, was studied. The conversion mechanism was analyzed as influenced by each component of the oxidizing solution.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  18. Photophysical comparative study of amylose and polyvinyle pyrrolidone / single walled carbon nanotubes complex.

    E-print Network

    Paris-Sud XI, Université de

    Photophysical comparative study of amylose and polyvinyle pyrrolidone / single walled carbon : pierre.m.bonnet@univ-bpclermont.fr ABSTRACT: Progressive addition of hydroxypropylated amylose (Am structures of (a): PVP; (b): Hydroxypropylated amylose (AmH). The circle shows the hydroxypropyl side group

  19. Preparation and Characterization of Atactic Poly(vinyl alcohol)\\/Platinum Nanocomposites by Electrospinning

    Microsoft Academic Search

    Won Seok Lyoo; Young Jae Lee; Jin Wook Cha; Min Jae Kim; Sang Woo Joo; Yeong Soon Gal; Tae Hwan Oh; Sung Soo Han

    2010-01-01

    Poly(vinyl alcohol) (PVA)\\/platinum composite nanofibers were successfully prepared by the electrospinning method. Water-based colloidal platinum in a PVA solution was directly mixed without any chemical or structural modifications into PVA polymer fibers to form organic-inorganic composite nanofibers. The PVA\\/platinum composite nanofibers were characterized by field emission scanning electron microscopy (SEM).

  20. Development of Meloxicam-Loaded Electrospun Polyvinyl Alcohol Mats as a Transdermal Therapeutic Agent

    Microsoft Academic Search

    Tanasait Ngawhirunpat; Praneet Opanasopit; Theerasak Rojanarata; Prasert Akkaramongkolporn; Uracha Ruktanonchai; Pitt Supaphol

    2009-01-01

    This study reports on the use of electrospun polyvinyl alcohol (PVA) nanofiber mats loaded with meloxicam (MX) as a transdermal drug delivery system. The amounts of MX loaded in the base PVA solution (10% w\\/v solution) were 2.5, 5, 10 and 20% weight, based on the dry weight of PVA (% wt). The average diameters of these fibers ranged from

  1. Preparation and Characterization of Atactic Poly(vinyl alcohol)/Platinum Nanocomposites by Electrospinning

    NASA Astrophysics Data System (ADS)

    Seok Lyoo, Won; Jae Lee, Young; Wook Cha, Jin; Jae Kim, Min; Woo Joo, Sang; Soon Gal, Yeong; Hwan Oh, Tae; Soo Han, Sung

    2010-06-01

    Poly(vinyl alcohol) (PVA)/platinum composite nanofibers were successfully prepared by the electrospinning method. Water-based colloidal platinum in a PVA solution was directly mixed without any chemical or structural modifications into PVA polymer fibers to form organic-inorganic composite nanofibers. The PVA/platinum composite nanofibers were characterized by field emission scanning electron microscopy (SEM).

  2. Optical dephasing of cresyl violet in a polyvinyl alcohol polymer by non-photochemical hole burning

    NASA Astrophysics Data System (ADS)

    Carter, T. P.; Fearey, B. L.; Hayes, J. M.; Small, G. J.

    1983-11-01

    A new burn—probe sequence is utilized with non-photochemical hole burning to study the optical dephasing of impurities in polymer films. For cresyl violet in polyvinyl alcohol the temperature dependence of dephasing is close to linear in the range studied. A burn time dependence of hole width is observed and discussed.

  3. Monitoring the photobleaching of cresyl violet in polyvinyl alcohol using the photoacoustic effect

    NASA Astrophysics Data System (ADS)

    Philip, Annieta; Radhakrishnan, P.; Nampoori, V. P.; Vallabhan, C. P.

    1994-06-01

    Bleaching of cresyl violet in polyvinyl alcohol due to irradiation by a laser beam at three chopping frequencies is investigated using the photoacoustic technique. The results indicate that the bleaching rate decreases with increase in chopping frequency. This can be used as a potential medium for holographic recording and information storage.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  5. Poly(vinyl chloride) polyacrylonitrile composite membranes for the dehydration of acetic acid

    Microsoft Academic Search

    G. H. Koops; J. A. M. Nolten-Oude Hendrikman; M. H. V. Mulder; C. A. Smolders

    1993-01-01

    Composite membranes have been prepared consisting of a poly(vinyl chloride) (PVC) top layer on either a dense polyacrylonitrile (PAN) layer (bi-layer membrane) or a porous PAN support layer (normal composite membrane) and studied with respect to the dehydration of acetic acid. Especially, the influence of the surface porosity of the porous support layer on the selectivity and flux was studied

  6. Study on miscibility of poly(vinyl chloride) and polyepichlorohydrin by viscometric and thermal analysis

    Microsoft Academic Search

    Yiming Ren; Ruizhu Yang; Xiaoli Liu; Fengqi Liu

    2011-01-01

    Viscometric analysis was carried out to study the miscibility of poly(vinyl chloride) (PVC) and polyepichlorohydrin (PECH) in various solvents, tetrahydrofuran (THF), methyl ethyl ketone (MEK) and dimethylformamide (DMF). The Krigbaum–Wall criterion is used here to evaluate the miscibility of the two components, and ?b is introduced which can be calculated from the viscosity curves. The results show that their attractive

  7. Synthesis and Magnetorheological Characterization of Magnetite Nanoparticle and Poly(Vinyl Butyral) Composite

    Microsoft Academic Search

    Bong Jun Park; Jae Lim You; Hyoung Jin Choi; Seong Yong Park; Byoung Yoon Lee

    2009-01-01

    Iron oxide nanoparticle of magnetite, one of well-known soft magnetic materials, has been investigated due to their various potential applications. In order to apply it as a magnetorheological (MR) material, composite of poly(vinyl butyral) and magnetite nanoparticles was prepared via solvent evaporation method using synthesized magnetite nanoparticles because of their proper magnetic characteristics and dispersion stability in a viscous medium.

  8. Structure-sensitive film materials based on polyvinyl alcohol compositions with polyacids

    Microsoft Academic Search

    Tatiana G. Lazareva; Irina A. Iljushenko

    1995-01-01

    The influence of polyacidic additives (silicotungstic acid -- STA, carboxymethylcellulose -- Na-CMC, polymethacrylic acid -- PMA, polyacrylic acid -- PAA) on the molecular mobility of film composition based on polyvinyl alcohol (PVA) in the temperature range 20 - 200 degree(s)C has been evaluated. It has been concluded that interpolymer complexes are formed due to hydrogen bonding of the PVA and

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

    SciTech Connect

    Oji, L.N.

    2000-01-04

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

  10. Antimicrobial Effect of An Essential Oil Blend on Surface-attached Salmonella on Polyvinyl Chloride

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The majority of drinking water lines for broilers are made of polyvinyl chloride (PVC) and surface attachment of Salmonella on the inner surface of water lines can be the initial stage of biofilm development. These biofilms can be the source of Salmonella infection in water lines and are known to re...

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

    PubMed

    Abdul-Majid, S; Othman, F

    1994-03-01

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

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

    SciTech Connect

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

    1994-03-01

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

  13. Composite Nafion\\/polyvinyl alcohol membranes for the direct methanol fuel cell

    Microsoft Academic Search

    Zhi-Gang Shao; Xin Wang; I.-Ming Hsing

    2002-01-01

    The methanol crossover in the direct methanol fuel cell (DMFC) can be reduced by casting a thin film containing the mixture of polyvinyl alcohol (PVA) and Nafion on a commercial perfluorosulfonic membrane (Nafion, Dupont). In addition to the cell polarization testing, a design factor defined as the reciprocal of the multiplication of the methanol permeation current density and membrane area

  14. Separation of Polyvinyl Chloride from Plastic Mixture by Froth Flotation after Surface Modification with Ozone

    Microsoft Academic Search

    Tetsuji Okuda; Keisuke Kurose; Wataru Nishijima; Mitsumasa Okada

    2007-01-01

    Selective modification by ozonation for the surface of polyvinyl chloride (PVC) was evaluated to separate PVC from the other plastics, polyethylene terephthalate (PET), polycarbonate (PC) and polymethyl methacrylate (PMMA), with almost the same density as PVC by the froth flotation process. Ozonation could selectively decrease the contact angles of flexible PVC from 87.5 degrees to 68.4 degrees and rigid PVC

  15. Synthesis of chemically crosslinked poly(vinyl chloride) by vinyl chloride\\/divinyls suspension copolymerization

    Microsoft Academic Search

    Yong-Zhong Bao; Zhi-Xue Weng; Zhi-Ming Huang; Zu-Ren Pan

    2000-01-01

    Vinyl chloride (VC)\\/divinyl derivative copolymerization was carried out in the suspension process for preparing chemically crosslinked poly(vinyl chloride) (PVC). Effects of the reactivity ratios and concentration of divinyl, polymerization temperature and conversion on the structure of crosslinked PVC (such as the gel fraction, polymerization degree of sol and crosslinking density of gel) were investigated. It showed that the crosslinking behavior

  16. THE EFFECT OF IRRADIATION ON THE DIELECTRIC PROPERTIES OF POLYVINYL CHLORIDE

    Microsoft Academic Search

    Kiessling

    1961-01-01

    The most important change which appears in the polyvinyl chloride (PVC) ; molecules following irradiation is the HCl-cleavage. It is combined with the ; originating macro molecular radical and unsaturated bonds. This reaction starts ; a series of further chemical reactions for which the presence or absence of ; oxygen in the reaction zone is of decisive importance. it was

  17. Chapter 5 Development of Adiabatic Force Field for Polyvinyl Chloride PVC

    E-print Network

    Goddard III, William A.

    73 Chapter 5 Development of Adiabatic Force Field for Polyvinyl Chloride PVC and Chlorinated PVC, dielectric, and ame and smoke properties, chemical inertness, and low sensitivity to hydrocarbon costs would be to determine the non-adiabatic surface by xing all bonds and angles so that only the torsional

  18. Adhesion of Poly(vinyl chloride) to Hydrogenated Nitrile Rubber Part 1: Peel Studies

    Microsoft Academic Search

    N. R. Manoj; P. P. De

    1994-01-01

    The adhesion of poly(vinyl chloride) to hydrogenated nitrile rub ber is studied by Tpeel test. The peel-fracture energy is found to be dependent on the presence of stabilizer and plasticizer in the PVC phase, in addition to the molding and testing conditions. At high contact temperatures and long contact times, in addition to the segmental diffusion across the interface, the

  19. Chemical modification of poly(vinyl chloride)—Still on the run

    Microsoft Academic Search

    S. Moulay

    2010-01-01

    Poly(vinyl chloride) (PVC) has continued to be a research topic in polymer science since its discovery in the early 19th century. Its internal structural defects, which stem from its direct manufacture (via free radical polymerization), heighten its peculiarities, including its thermal instability. Apart from the addition of organic and inorganic thermal stabilizers, improved chemistry in the formation of PVC has

  20. Preparation of polyvinyl alcohol-polyacrylamide composite polymer membrane by ?-irradiation for entrapment of urease

    Microsoft Academic Search

    Sandeep Kumar Jha; Stanislaus F. D'Souza

    2005-01-01

    Composite polymer membrane of polyvinyl alcohol (PVA) and acrylamide was prepared on cheesecloth support by ?-irradiation induced free radical polymerization. The enzyme urease was entrapped in the membrane during polymerization and was cross-linked within the matrix using glutaraldehyde. The membranes could be reused a number of times without significant loss of urease activity.

  1. Comparative study on polyvinyl alcohol and alginate for cell immobilization in biosorption

    Microsoft Academic Search

    Y. P. Ting; G. Sun

    2000-01-01

    In this work, we compared the performance of a new method of cell immobilization in a novel matrix for biosorption. Yeast cells were entrapped in a polyvinyl alcohol (PVA) matrix, based on an adapted iterative freeze-thaw-freeze process. Spherical and uniform beads were produced, and SEM micrographs confirmed that the cells were uniformly dispersed within the PVA matrix. Further experiments revealed

  2. Modification of cellulosic fabric using polyvinyl alcohol, Part-II: Colorfastness properties

    Microsoft Academic Search

    Mohammad Zuber; Khalid Mahmood Zia; Ijaz Ahmad Bhatti; Tahir Jamil; Ali Rizwan

    A series of aqueous solutions of poly (vinyl alcohol) of various commercial products were prepared and applied onto the surfaces of cotton and blends of cotton\\/polyester fabrics. Fourier Transform Infrared spectrophotometer was used to confirm the molecular structure of the polyvinyl alcohol used. Performance tests such as colorfastness to rubbing (dry and wet) and colorfastness to washing were determined. The

  3. DSC and FTIR studies on Gellan and Polyvinyl alcohol (PVA) blend films

    Microsoft Academic Search

    S. R Sudhamani; M. S Prasad; K Udaya Sankar

    2003-01-01

    Homopolymer films of Gellan and polyvinyl alcohol (PVA) and blended films were prepared by a solution casting method from a polymer solution in water of Gellan and PVA using glycerol as plasticizer. The films were studied for thermal characteristics by differential scanning calorimetry, for intermolecular interactions by Fourier transform infrared spectroscopy and for the mechanical properties of tear strength, tensile

  4. Recent advances in starch, polyvinyl alcohol based polymer blends, nanocomposites and their biodegradability

    Microsoft Academic Search

    Xiaozhi Tang; Sajid Alavi

    2011-01-01

    Recent environmental regulations, societal concerns and growing environmental understanding throughout the world have triggered renewed efforts in plastic industry to develop new products and processes compatible with our environment. This review outlines the new developments in thermoplastic starch, polyvinyl alcohol based blends and nanocomposites. These materials show a broad and versatile range of physical properties and other advantageous characteristics at

  5. Mechanistic analysis of protein delivery from porous poly(vinyl alcohol) systems

    E-print Network

    Peppas, Nicholas A.

    285 Mechanistic analysis of protein delivery from porous poly(vinyl alcohol) systems N.A. Peppas hydrogels are cross-linked networks of hydrophilic polymers that are used as versatile releasematerials is one of the few polymers that exhibit this phenomenon. Its crystalline regions serve as cross-linking

  6. Li ion conducting gel polymer electrolytes based on Poly(vinyl acetate)

    NASA Astrophysics Data System (ADS)

    Rajendran, S.; Mathew, Chithra M.; Marimuthu, T.; Kesavan, K.

    2013-06-01

    A novel gel polymer electrolyte based on poly(vinyl acetate) and poly(vinylidene fluoride) with different plasticizers was prepared and studied by X-ray diffraction and Ac impedance methods. The blend polymer electrolyte containing propylene carbonate (PC) exhibits the highest conductivity 0.922 × 10-2 Scm-1 at room temperature and the results were discussed.

  7. In vivo calcium deposition on polyvinyl alcohol matrix used in hollow fiber cell macroencapsulation devices

    Microsoft Academic Search

    F. Schwenter; N. Bouche; W.-F. Pralong; P. Aebischer

    2004-01-01

    The encapsulation of genetically modified cells represents a promising approach for the delivery of therapeutic proteins. The functionality of the device is dependent on the characteristics of the biomaterials, the procedures used in its confection and the adaptability of the encapsulated cells in the host. We report conditions leading to the development of calcifications on the polyvinyl alcohol (PVA) matrix

  8. Cost-effectiveness of silicone and alginate impressions for complete dentures

    PubMed Central

    Hulme, C.; Yu, G.; Browne, C.; O’Dwyer, J.; Craddock, H.; Brown, S.; Gray, J.; Pavitt, S.; Fernandez, C.; Godfrey, M.; Dukanovic, G.; Brunton, P.; Hyde, T.P.

    2014-01-01

    Objective The aim of this study was to assess the cost effectiveness of silicone and alginate impressions for complete dentures. Methods Cost effectiveness analyses were undertaken alongside a UK single centre, double blind, controlled, crossover clinical trial. Taking the perspective of the healthcare sector, effectiveness is measured using the EuroQol (EQ-5D-3L) which provides a single index value for health status that may be combined with time to produce quality adjusted life years (QALYs); and Oral Health Impact Profile (OHIP-EDENT). Incremental cost effectiveness ratios are presented representing the additional cost per one unit gained. Results Mean cost was higher in the silicone impression group (£388.57 vs. £363.18). Negligible between-group differences were observed in QALY gains; the silicone group had greater mean OHIP-EDENT gains. The additional cost using silicone was £3.41 per change of one point in the OHIP-EDENT. Conclusions The silicone group was more costly, driven by the cost of materials. Changes in the EQ-5D and QALY gains over time and between arms were not statistically significant. Change in OHIP-EDENT score showed greater improvement in the silicone group and the difference between arms was statistically significant. Given negligible QALY gains and low level of resource use, results must be treated with caution. It is difficult to make robust claims about the comparative cost-effectiveness. Clinical significance Silicone impressions for complete dentures improve patients’ quality of life (OHIP-EDENT score). The extra cost of silicone impressions is £30 per patient. Dentists, patients and health care funders need to consider the clinical and financial value of silicone impressions. Different patients, different dentists, different health funders will have individual perceptions and judgements. ISRCTN01528038. NIHR-RfPB grant PB-PG-0408-16300.?? This article forms part of a project for which the author (TPH) won the Senior Clinical Unilever Hatton Award of the International Assocation for Dental Research, Capetown, South Africa, June 2014. PMID:24995472

  9. The clinical, histologic, and ultrastructural presentation of polyvinyl sponge (Ivalon) breast prostheses removed for massive fluid accumulation.

    PubMed

    Smith, A R; Garrison, J L; Greene, W B; Raso, D S

    1999-06-01

    The current study describes what we believe is the first report of bilateral massive seromas associated with open-cell Ivalon sponges. Additionally, the gross, histologic, and ultrastructural features consistent with previous reports of polyvinyl alcohol prostheses are presented. Despite the reported chemical inertness of polyvinyl alcohol, this material may incite a biologic response in some patients, leading to dense fibrosis and occasional foreign-body giant-cell reaction. It is postulated that the molecular breakdown products of the polyvinyl alcohol polymer may create an osmotic gradient across the periprosthetic capsule, which may lead to intracapsular fluid accumulation, as presented in this case. PMID:10359261

  10. Good soldiers and good actors: prosocial and impression management motives as interactive predictors of affiliative citizenship behaviors.

    PubMed

    Grant, Adam M; Mayer, David M

    2009-07-01

    Researchers have discovered inconsistent relationships between prosocial motives and citizenship behaviors. We draw on impression management theory to propose that impression management motives strengthen the association between prosocial motives and affiliative citizenship by encouraging employees to express citizenship in ways that both "do good" and "look good." We report 2 studies that examine the interactions of prosocial and impression management motives as predictors of affiliative citizenship using multisource data from 2 different field samples. Across the 2 studies, we find positive interactions between prosocial and impression management motives as predictors of affiliative citizenship behaviors directed toward other people (helping and courtesy) and the organization (initiative). Study 2 also shows that only prosocial motives predict voice-a challenging citizenship behavior. Our results suggest that employees who are both good soldiers and good actors are most likely to emerge as good citizens in promoting the status quo. PMID:19594233

  11. A Comparison of Stainless Steel Hand and Rotary Nickel-Titanium Instrumentation Using a Silicone Impression Technique

    Microsoft Academic Search

    JL Chen; HH Messer

    2002-01-01

    Background: Root canal preparation using rotary nickel-titanium instruments has been reported to be superior to hand instrumentation in terms of root canal shape, centring and frequency of procedural errors. The purpose of this study was to evaluate canal preparations using a sequential silicone impression technique to assess root canal morphology. Methods: Pre-operative canal impressions were obtained from 24 extracted single-rooted

  12. METAL COMPLEXING SILOXANE POLYMERS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Novel silicone polymers containing pendant phosphonate groups have been synthesized. A new silicone monomer, (CH3O)2CH3Si(CH2)3P=O(OCH2CH3)2 has been copolymerized with dimethyldimethoxysilane to form polymers capable of binding metal salts. The viscous liquids can complex a variety of metals, inc...

  13. Maleimide Functionalized Siloxane Resins

    SciTech Connect

    Shaltout, R.M.; Loy, D.A.; Wheeler, D.R.

    1999-04-21

    In-situ filling through hydrolysis and condensation of silicon alkoxides has been utilized to generate nanocomposites in which the filler phase can be intimately associated with the polymer on relatively small length scales. One problem of the method has been achieving useful fill volumes without bulk phase separation of the reacting silicon monomer from the polymer. In this paper, we describe the preparation of a new class of nanocomposite materials in which the inorganic filler phase is pre-assembled before copolymerization with an organic species. Maleimide monomers, prepared from alkoxysilylpropyl amines and maleic anhydride, were protected against side reactions by forming the oxonorbornene Diels-Alder adduct with furan. The monomers were then reacted under sol-gel conditions to form oligomers or polymers-the filler phase. The material was activated by thermal deprotection of the maleimide and reacted with organic monomers or polymers to form the filled nanocomposite.

  14. Determination of organophosphorus pesticides in ecological textiles by solid-phase microextraction with a siloxane-modified polyurethane acrylic resin fiber.

    PubMed

    Hu, Xianlei; Zhang, Mingqiu; Ruan, Wenhong; Zhu, Fang; Ouyang, Gangfeng

    2012-07-29

    A novel solid-phase microextraction (SPME) fiber coating was prepared with siloxane-modified polyurethane acrylic resin by photo-cured technology. The ratio of two monomers was investigated to obtain good microphase separation structure and better extraction performance. The self-made fiber was then applied to organophosphorus pesticides (OPPs) analysis and several factors, such as extraction/desorption time, extraction temperature, salinity, and pH, were studied. The optimized conditions were: 15 min extraction at 25 °C, 5% Na(2)SO(4) content, pH 7.0 and 4 min desorption in GC inlet. The self-made fiber coating exhibited better extraction efficiency for OPPs, compared with three commercial fiber coatings. Under the optimized conditions, the detection limits of 11 OPPs were from 0.03 ?g L(-1) to 0.5 ?g L(-1). Good recoveries and repeatabilities were obtained when the method was used to determine OPPs in ecological textile. PMID:22769006

  15. Sulawesi tortoise adenovirus-1 in two impressed tortoises (Manouria impressa) and a Burmese star tortoise (Geochelone platynota).

    PubMed

    Schumacher, Vanessa L; Innis, Charles J; Garner, Michael M; Risatti, Guillermo R; Nordhausen, Robert W; Gilbert-Marcheterre, Kelly; Wellehan, James F X; Childress, April L; Frasca, Salvatore

    2012-09-01

    Sulawesi tortoise adenovirus-1 (STAdV-1) is a newly discovered virus infecting endangered and threatened tortoises. It was initially described from a confiscated group of 105 Sulawesi tortoises (Indotestudo forsteni) obtained by the Turtle Survival Alliance and distributed to five sites with available veterinary care across the United States. In a 3-yr period from the initial outbreak, one multi-species collection that rehabilitated and housed adenovirus-infected Sulawesi tortoises experienced deaths in impressed tortoises (Manouria impressa) and a Burmese star tortoise (Geochelone platynota). Impressed tortoises that died had evidence of systemic viral infection with histopathologic features of adenovirus. Adenovirus was identified by consensus nested polymerase chain reaction (PCR) testing and subsequent sequencing of PCR products. Sequencing indicated that the adenovirus infecting these impressed tortoises and Burmese star tortoise was STAdV-1. In one impressed tortoise, viral infection was confirmed using transmission electron microscopy. In situ hybridization using a semiautomated protocol and fluorescein-labeled riboprobe identified STAdV-1 inclusions in spleen, liver, kidney, and testis of one impressed tortoise. The impact of this virus on captive and wild populations of tortoises is unknown; however, these findings indicate that STAdV-1 can be transmitted to and can infect other tortoise species, the impressed tortoise and Burmese star tortoise, when cohabitated with infected Sulawesi tortoises. PMID:23082513

  16. Effects of Concentration of Organically Modified Nanoclay on Properties of Sulfonated Poly(vinyl alcohol) Nanocomposite Membranes

    E-print Network

    Sanglimsuwan, Apiradee

    Electrolyte nanocomposite membranes for proton exchange membrane fuel cells and direct methanol fuel cells were prepared by carrying out a sulfonation of poly(vinyl alcohol) with sulfosuccinic acid and adding a type of ...

  17. Infrared absorption and vibrational circular dichroism spectra of poly(vinyl ether) containing diastereomeric menthols as pendants

    Microsoft Academic Search

    Jennifer L. McCann; Arvi Rauk; Hal Wieser

    1997-01-01

    The absorption and vibrational circular dichroism (VCD) spectra in the 1700 to 830 cm?1 region are reported and qualitatively interpreted for poly(vinyl ether) with (+)-menthol (I), (+)-isomenthol (II) and (+)-neomenthol (III) as pendants.

  18. Cell phones, clothing, and sex: first impressions of power using older African Americans as stimuli.

    PubMed

    Ross, Allison; Barker, Kathleen

    2003-12-01

    Sex, material possessions, and race have long been associated with prestige or status in American society, yet little research has examined this idea. Little is known about the effect of cell phones on first impressions. In a 2 (cell phone: present, absent) x 2 (clothing: jacket, no jacket) x 2 (sex) between-subjects design, 160 women from a predominantly Black college rated stimuli of older, African Americans on 15 items measuring perceived power on three power subscales: expert, legitimate, and coercive. Multivariate analysis of variance showed a 3-way interaction for clothing, cell phone, and sex of stimulus person. PMID:14723458

  19. The effects of sterilization on the accuracy of silicone ear impression materials.

    PubMed

    Salem, N S; Combe, E C; Nolan, M

    1989-01-01

    The dimensional stability of a range of elastomeric impression materials has been assessed to study the effect of storage in sterilizing solutions. Experiments were carried out on audiological silicones of condensation and addition types. Further, a number of dental-based materials comprising a polysulphide, a polyether, a condensation and an addition silicone, were also investigated for comparison. The results indicate that the addition silicones had the greatest dimensional stability over a range of storage conditions, which included aqueous glutaraldehyde and hypochlorite solutions. PMID:2814324

  20. Surface and Interfacial Structure of Release Coatings for Pressure Sensitive Adhesives I. Polyvinyl N-Alkyl Carbamates

    Microsoft Academic Search

    David J. Kinning

    1997-01-01

    Polyvinyl N-alkyl carbamates belong to the general class of long alkyl side chain polymers. Such polymers are commonly used as release coatings for pressure sensitive adhesive tapes. In this paper the bulk, surface, and interfacial structures of polyvinyl N-alkyl carbamates having either decyl or octadecyl side chains are examined. The bulk structures and thermal transitions were characterized using X-ray scattering

  1. Synthesis and characterization of polyvinyl alcohol based multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    Malikov, E. Y.; Muradov, M. B.; Akperov, O. H.; Eyvazova, G. M.; Puskás, R.; Madarász, D.; Nagy, L.; Kukovecz, Á.; Kónya, Z.

    2014-07-01

    Multiwalled carbon nanotubes were synthesized by chemical vapor deposition over an Fe-Co/alumina catalyst. Nanotubes were then oxidized and grafted with polyvinyl alcohol (PVA). The obtained nanostructure was characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM, TEM and TGA methods. FTIR confirmed the presence of the characteristic peaks of the anticipated ester group. The formation of polymer nanocomposites based on polyvinyl alcohol and multiwalled carbon nanotubes was confirmed by SEM and TEM. High resolution electron micrographs revealed that the primary binding sites for PVA grafting are the sidewall defects of the nanotubes. The novelty of this work is the use of the Fischer esterification reaction for creating the permanent link between the nanotubes and the PVA matrix.

  2. In-situ cross linking of polyvinyl alcohol. [application to battery separator films

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    A method of producing a crosslinked polyvinyl alcohol structure, such as a battery separator membrane or electrode envelope is described. An aqueous solution of a film-forming polyvinyl alcohol is admixed with an aldehyde crosslinking agent a basic pH to inhibit crosslinking. The crosslinking agent, perferably a dialdehyde such as glutaraldehyde, is used in an amount of from about 1/2 to about 20% of the theoretical amount required to crosslink all of the hydroxyl groups of the polymer. The aqueous admixture is formed into a desired physical shape, such as by casting a sheet of the solution. The sheet is then dried to form a self-supporting film. Crosslinking is then effected by immersing the film in aqueous acid solution. The resultant product has excellent properties for use as a battery separator.

  3. Survey of 1276 shoeprint impressions and development of an automatic shoeprint pattern matching facility.

    PubMed

    Hannigan, T J; Fleury, L M; Reilly, R B; O'Mullane, B A; deChazal, P

    2006-01-01

    1276 shoeprints were collected at a scientific exhibition. Details regarding the age groups of the participants, style, size and manufacturer/brand of their shoes were recorded. The impressions were assigned to pattern groups showing that the most common pattern was present in only 1% of the population studied and most patterns were much less common. The impressions were digitized and a system developed for automatically sorting a database of images of outsole patterns in response to a reference image. The database images are ranked so that those from the same pattern group as the reference shoeprint are likely to be at the start of the list. A database of 486 complete shoeprint images belonging to 142 pattern groups was established with each group containing two or more examples. Tests of the system have shown that the first-ranked database image belongs to the same pattern group as the reference image 60% of the time and that a correct match appears within the first 5% of the ranked images 88% of the time. The system has translational and rotational invariance so that the spatial positioning of the reference shoeprint images does not have to correspond with the spatial positioning of the shoeprint images of the database. The performance of the system for matching partial shoeprints was also determined. PMID:17002210

  4. Appraisals and impression management opportunities: person and situation influences on cardiovascular reactivity.

    PubMed

    Heffner, Kathi L; Ginsburg, G P; Hartley, Terry R

    2002-05-01

    This study examined how threat and coping appraisals and impression management opportunities influenced cardiovascular reactivity within a self-presentation context. Participants were videotaped performing a speech that they believed might be evaluated. Participants' physiological responses were recorded 1 week later while: (a) watching their speech, indicating which portions they wished to re-shoot before it was evaluated,;(b) simply watching their speech; or (c) watching an architectural videotape and indicating which portions should be reshot, and also watching their own speech, but without evaluation concerns. Cardiovascular reactivity was influenced by the presence or absence of the impression management opportunity, but more variance in reactivity was explained when participants' threat and coping appraisals were also taken into account. The specific cardiovascular responses pertinent to goal-relevant action within each condition were the only responses related to appraisals. These findings emphasize the importance of considering both the situation and the state of the individual in that situation when attempting to understand social psychological influences on physiological reactivity. PMID:11909648

  5. Taxometric analysis of impression management and self-deception in college student and personnel evaluation settings.

    PubMed

    Strong, David R; Greene, Roger L; Kordinak, S Thomas

    2002-02-01

    The typology of impression management (IM), a deliberate attempt to create a positive social image, and self-deceptive positivity (SDP), an overly positive bias in self-description, was examined using taxometric procedures with Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) underreporting scales and Balanced Inventory of Desirable Responding (Paulhus, 1988) impression management and SDP scales in a sample of college students. MMPI-2 underreporting scales were then examined in a personnel evaluation sample. IM was found to be taxonic in both student and personnel settings. Given support for the IM taxon, taxometric procedures allow the estimation of the base rate of IM and the classification accuracy of MMPI-2 IM scales in the absence of a separate criterion. Using taxometric procedures, the mean base-rate estimates were .16 and .25 for student and personnel settings, respectively. Overall classification rates ranged from .80 to .94 for MMPI-2 IM scales in the personnel setting. PMID:11936207

  6. Influence of inner circular sealing area impression method on the retention of complete dentures.

    PubMed

    Wang, Cun-Wei; Shao, Qi; Sun, Hui-Qiang; Mao, Meng-Yun; Zhang, Xin-Wei; Gong, Qi; Xiao, Guo-Ning

    2015-01-01

    The aims of the present study were to describe an impression method of "inner circular sealing area" and to evaluate the effect of the method on retention, aesthetics and comfort of complete dentures, which lack labial base for patients with maxillary protrusions. Three patients were subjected to the experiment, and two sets of complete maxillary dentures were made for each patient; the first set was made without labial base via an inner circular sealing area method (experimental group) and the second had an intact base that was made with conventional methods (control group). Retention force tests were implemented with a tensile strength assessment device to assess the retention and a visual analogue scale (VAS) was used to evaluate the comfort between the two groups. Results showed larger retention force, better aesthetics and more comfort in the experimental group. The improved two-step impression method formed an inner circular sealing area that prevented damage to the peripheral border seal effect of the denture caused by incomplete bases and obtained better denture retention. PMID:25831114

  7. Treatment of edentulism: optimizing outcomes with tissue management and impression techniques.

    PubMed

    Salinas, Thomas J

    2009-02-01

    Significant numbers of patients throughout the world seek treatment for edentulism. The trend toward tissue-integrated prostheses has been a monumental step in restoring edentulous patients to function; however, this treatment can be out of reach for those who fail to qualify or those who do not have sufficient resources to afford it. In these cases, conventional dentures remain an important primary course of treatment. Attention to detail when diagnosing, treatment planning, and performing treatment for these patients is still a prime consideration for the best possible outcome. In particular, many experienced denture wearers are afflicted with chronically inflamed denture-bearing mucosa. Clinicians must recognize the need for tissue conditioning, choices of impression materials, and accepted fabrication techniques that can have favorable outcomes when matched with patients who are philosophical and realistic in their expectations. The purpose of this article is to review impression philosophies, associated materials, and methods of tissue conditioning. Retention and stability of the denture bases can be augmented by the routine use of denture adhesive, and indications for use of denture adhesive will be discussed. PMID:19254298

  8. Preparation of Colloidal Rhodium in Poly(vinyl Alcohol) by Reduction with Methanol

    Microsoft Academic Search

    Hidefumi Hirai; Yukimichi Nakao; Naoki Toshima

    1978-01-01

    Refluxing of a solution of poly(vinyl alcohol) and rhodium(III) chloride in methanol-water gives a colloidal dispersion of rhodium which is an effective catalyst for hydrogenation of cyclohexene in methanol at 30°C under atmospheric hydrogen pressure. Formaldehyde is produced quantitatively with the reduction of rhodium(III) chloride to metallic rhodium. The rhodium particles in the colloidal dispersion are found to consist of

  9. Influence of polymer additives on thermal decomposition and smoke emission of poly(vinyl chloride)

    Microsoft Academic Search

    Bin Li

    2003-01-01

    The influence of polymer additives and metal oxides on thermal decomposition and smoke suppression of poly(vinyl chloride) was investigated using a cone calorimeter at an incident heat flux of 25 kW m?2. Acrylate (acrylic K120N), chlorinated polyethylene, PVC-MC100 and polyethylene wax were used as polymer additives, and metal oxides including CuO, MoO3 and FeOOH as smoke suppressants. The experimental data

  10. Strain hardening behavior of lightweight hybrid polyvinyl alcohol (PVA) fiber reinforced cement composites

    Microsoft Academic Search

    Shaikh Faiz Uddin Ahmed; Hirozo Mihashi

    2011-01-01

    Experimental results on the strain hardening and multiple cracking behaviors of polyvinyl alcohol (PVA) fiber reinforced cementitious\\u000a composites under bending are reported in this paper. Different hybrid combinations of PVA fibers with different lengths and\\u000a volume fractions are considered to reinforce the mortar matrix. Among different hybrid combinations, the composite containing\\u000a 2% thicker PVA fibers of 12 mm length and 1%

  11. Swelling behavior of interpenetrating polymer network hydrogels composed of poly(vinyl alcohol) and chitosan

    Microsoft Academic Search

    Seon Jeong Kim; Sang Jun Park; Sun I. Kim

    2003-01-01

    Interpenetrating polymer network (IPN) hydrogels composed of poly(vinyl alcohol) (PVA) and chitosan were prepared by UV irradiation. The characteristics of IPN hydrogels were investigated by swelling experiments, Fourier transform infrared (FT-IR) spectroscopy and differential scanning calorimetry (DSC). IPN hydrogels exhibited a relatively high swelling ratio in the range of 210–350% at 35°C. The swelling ratio of PVA\\/chitosan IPN hydrogels depended

  12. Preparation and property of polyvinyl alcohol-based film embedded with gold nanoparticles

    Microsoft Academic Search

    Changmei Sun; Rongjun Qu; Chunnuan Ji; Yanfeng Meng; Chunhua Wang; Yanzhi Sun; Lingyan Qi

    2009-01-01

    Gold nanoparticles were prepared by a simple heat-treated method using polyvinyl alcohol (PVA) as reducing and stabilizing\\u000a agent in this article. UV\\/Vis spectroscopy was used to monitor the preparation. The formation of a sharp band at ~530 nm in\\u000a the UV\\/Vis spectra and morphological characters revealed by transmission electron microscopy indicated the generation of Au\\u000a nanoparticles. The PVA film embedded with

  13. Inhibition of nucleation and growth of ice by poly(vinyl alcohol) in vitrification solution

    Microsoft Academic Search

    Hai-Yan Wang; Takaaki Inada; Kunio Funakoshi; Shu-Shen Lu

    2009-01-01

    Control of ice formation is crucial in cryopreservation of biological substances. Successful vitrification using several additives that inhibit ice nucleation in vitrification solutions has previously been reported. Among these additives, here we focused on a synthetic polymer, poly(vinyl alcohol) (PVA), and investigated the effects of PVA on nucleation and growth of ice in 35% (w\\/w) aqueous 1,2-propanediol solution by using

  14. Miscibility and morphology of blends of poly(3-hydroxybutyrate) and poly(vinyl butyral)

    Microsoft Academic Search

    Wenjie Chen; Donald J David; William J MacKnight; Frank E Karasz

    2001-01-01

    The miscibility and morphology of blends of biodegradable poly(3-hydroxybutyrate) (PHB) and poly(vinyl butyral) (PVB) were studied by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). PHB is a semi-crystalline polymer while PVB can be regarded as a random copolymer containing vinyl butyral (VB) and vinyl alcohol (VA) units whose composition ratio can be systematically changed over a wide range.

  15. Assessing biodegradability of plastics based on poly(vinyl alcohol) and protein wastes

    Microsoft Academic Search

    Jarom??r Hoffmann; Iveta ?ezn???ková; Jarmila Kozáková; Jan R?ži?ka; Pavol Alexy; Dušan Bakoš; Lenka Precnerová

    2003-01-01

    Research was conducted into biodegradability of mixed polymer films based on poly(vinyl alcohol), protein hydrolyzate (collagen hydrolyzate from wastes after chrome tanning) and glycerol in an aqueous aerobic environment. Evaluation of biodegradation was based on carbon dioxide produced in the gas phase. Pure PVAL was degraded by a current mixed culture for water-treatment (unadapted) only after an approx. 10-day lag

  16. Relaxation phenomena in poly(vinyl alcohol)\\/fumed silica affected by interfacial water

    Microsoft Academic Search

    V. M. Gun'ko; P. Pissis; A. Spanoudaki; V. I. Zarko; Y. M. Nychiporuk; L. S. Andriyko; E. V. Goncharuk; R. Leboda; J. Skubiszewska-Zi?ba; V. D. Osovskii; Y. G. Ptushinskii

    2007-01-01

    Interaction of poly(vinyl alcohol) (PVA) with fumed silica was investigated in the gas phase and aqueous media using adsorption, broadband dielectric relaxation spectroscopy (DRS), thermally stimulated depolarization current (TSDC), infrared spectroscopy, thermal analysis, and one-pass temperature-programmed desorption (OPTPD) mass-spectrometry (MS) methods. PVA monolayer formation leads to certain textural changes in the system (after suspension and drying) because of strong hydrogen

  17. Chemical alteration of poly(vinyl fluoride) Tedlar by hyperthermal atomic oxygen

    Microsoft Academic Search

    Gar B. Hoflund; Michael L. Everett

    2005-01-01

    In this study the erosion of poly(vinyl fluoride) Tedlar by hyperthermal atomic oxygen (AO) has been examined using X-ray photoelectron spectroscopy (XPS). Initially the Tedlar film had F\\/C and O\\/C atom ratios of 0.45 and 0.11, which decrease to 0.018 and 0.04, respectively, after a 2-h exposure to a flux of 2 × 1015atoms\\/cm2s AO with an average kinetic energy

  18. Chemical alteration of poly(vinyl fluoride) Tedlar ® induced by exposure to vacuum ultraviolet radiation

    Microsoft Academic Search

    Michael L. Everett; Gar B. Hoflund

    2006-01-01

    In this study the chemical alteration of poly(vinyl fluoride) Tedlar® by vacuum ultraviolet radiation (VUV) (115–400nm) has been examined using X-ray photoelectron spectroscopy (XPS). The initial F\\/C atom ratio of 0.34 decreases to 0.17 after a 2-h exposure. The F\\/C atom ratio is further reduced to a steady-state value of approximately 0.04 after a 24-h exposure. Similarly, the O\\/C atom

  19. Vinyl chloride and polyvinyl chloride: Toxicology. (Latest citations from the Life Sciences Collection database). Published Search

    SciTech Connect

    NONE

    1995-12-01

    The bibliography contains citations concerning the toxicity of vinyl chloride and polyvinyl chloride following short- and long-term exposure. The citations explore how these compounds are metabolized and consider their carcinogenic and teratogenetic potential. Methodologies to quantitate their presence in atmospheric dust and body tissues are discussed. Occupational hazards are also noted.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  20. Preparation of the poly(vinyl alcohol)/layered double hydroxide nanocomposite

    SciTech Connect

    Li Baoguang; Hu Yuan; Zhang Rui; Chen Zuyao; Fan Weicheng

    2003-10-01

    Intercalated nanocomposite based on Mg, Al layered double hydroxide (LDH) and poly(vinyl alcohol) (PVA) was prepared using exfoliation-adsorption technique, and characterized by X-ray diffraction and thermal gravimetric analysis. The results suggest that the intercalated species are formed via the re-aggregation of the delaminated LDH lamellar with the interlayer spacing 14.5 A, and the thermal stability of the nanocomposite improved compared with the original PVA.