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1

Comparison of the effect of different medicaments on surface reproduction of two commercially available Polyvinyl Siloxane impression materials - An Invitro Study  

PubMed Central

Objective:To determine the effect of different retraction cord medicaments on surface detail reproduction of polyvinyl siloxane impression materials and compare this effect on any two brands of commercially available polyvinyl siloxane impression materials. Material and methods: Four stainless steel dies were made according to ADA specification no.19. Three dies were treated with aluminium chloride (5%), ferric sulphate (13.3%) and epinephrine (0.1%) while the fourth one was left untreated to serve as control. Two impression materials (Dentsply and 3M ESPE) were used. Results: All the three medicaments adversely affected the surface detail reproduction of both the brands of the polyvinyl siloxane impression materials. These effects were statistically significant as compared to untreated control. The impressions of 3M ESPE brand have shown better surface detail reproduction as compared to Dentsply impression material. Conclusion: Surface detail reproduction of the polyvinyl siloxane impression materials is adversely affected by the retraction cord medicaments. The presence of moisture or any traces of the medicaments should be removed from the tooth surface to provide a dry field for the correct reproduction of the surface detail of these materials. Key words:Polyvinyl Siloxane, retraction cord medicaments, surface detail reproduction.

Singh, Rina; Singh, Jagjit; Singh, Ramanpreet; Nanda, Sonia

2013-01-01

2

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

PubMed Central

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.

Dugal, Ramandeep; Railkar, Bhargavi; Musani, Smita

2013-01-01

3

Pressure produced on the residual maxillary alveolar ridge by different impression materials and tray design: an in vivo study.  

PubMed

Increased ridge resorption may occur due to inappropriate pressure applied during final impression making phase of complete denture fabrication. This study was done to evaluate the pressure applied on the residual ridge while making impressions with two tray designs (with and without spacer) using, zinc oxide eugenol and light body polyvinyl siloxane impression material. Five edentulous subjects were randomly selected. For each of the five subjects four maxillary final impressions were made and were labelled as, Group A-Impression made with tray without spacer using zinc oxide eugenol impression, Group B-Impression made with tray with spacer using zinc oxide eugenol impression material, Group C-Impression made with tray without spacer using light body polyvinyl siloxane impression material, Group D-Impression made with tray with spacer using light body polyvinyl siloxane impression material. During the impression procedure a closed hydraulic system was used to remotely measure the pressures produced in three areas. The pressure produced were calibrated according to the micro strain record. Statistical comparisons of readings were done using t test and ANOVA. The acquired data revealed that ZOE produced an average pressures value of 26.534 and 72.05 microstrain, while light body PVS produced 11.430 and 37.584 microstrain value with and without spacer respectively. Significantly high values were recorded on the vault of the palate when using trays without spacer. The use of light body polyvinyl siloxane and zinc oxide eugenol impression material showed insignificant difference. Within the limitations of this study, tray design has a significantly effected on the pressures produced, while the impression materials does not have any significant difference. PMID:24431783

Reddy, Subash M; Mohan, Chenthil Arun; Vijitha, D; Balasubramanian, R; Satish, A; Kumar, Mahendira

2013-12-01

4

Assessment of open and incomplete bite correction by incisor overlap and optical density of polyvinyl siloxane bite registration.  

PubMed

Open bite (OB) is a generalized term, which could incorporate subgroups that react differently to vertical correction. The objectives of the present study were to detect vertical treatment changes in incomplete bite (IB: inter-incisor overlap with no lower incisor contact with teeth or palate) and OB (no inter-incisor overlap) groups compared with a complete bite (CB: inter-incisor overlap with full lower incisor contact with teeth or palate) control group, to evaluate treatment response of the central and lateral incisors, and to study the vertico-sagittal interaction. Dental casts were taken at three time points, pre-treatment, post-treatment, and after one year of retention, from 54 Class II patients (22 males and 32 females with a mean age of 11 years 6 months) divided into three groups: CB (n = 21), IB (n = 18) and OB (n = 15). Measurements included incisor overlap (mm) and optical density (OD/mm2) of occlusal bite registration made of polyvinl siloxane. Both CB and IB groups demonstrated post-retention bite opening. However, bite opening in the CB group was three times greater than that in the IB group (e.g. lower lateral = -1.42 mm, 118 OD/mm2 versus -0.40 mm, 107 OD/mm2). Conversely, the OB group showed a significant (P < 0.001) bite closure (e.g. lower lateral = 1.30 mm, -377 OD/mm2). Overjet changes affected OD measurements, causing diversity in OD and millimetric measurements of the lateral incisors in the IB group. In conclusion, the OB group demonstrated a significant stable vertical correction; a post-treatment non-contact inter-incisor relationship was determined by a vertico-sagittal relapse; and full compensation of an IB was not possible. PMID:16267127

Shpack, Nir; Einy, Shmuel; Beni, Lea; Vardimon, Alexander D

2006-04-01

5

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

PubMed

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

Naveen, Y G; Patil, Raghunath

2013-03-01

6

Effect of various putty-wash impression techniques on marginal fit of cast crowns.  

PubMed

Marginal fit is an important clinical factor that affects restoration longevity. The accuracy of three polyvinyl siloxane putty-wash impression techniques was compared by marginal fit assessment using the nondestructive method. A stainless steel master cast containing three abutments with three metal crowns matching the three preparations was used to make 45 impressions: group A = single-step technique (putty and wash impression materials used simultaneously), group B = two-step technique with a 2-mm relief (putty as a preliminary impression to create a 2-mm wash space followed by the wash stage), and group C = two-step technique with a polyethylene spacer (plastic spacer used with the putty impression followed by the wash stage). Accuracy was assessed using a toolmaker microscope to measure and compare the marginal gaps between each crown and finish line on the duplicated stone casts. Each abutment was further measured at the mesial, buccal, and distal aspects. One-way analysis of variance was used for statistical analysis. P values and Scheffe post hoc contrasts were calculated. Significance was determined at .05. One-way analysis of variance showed significant differences among the three impression techniques in all three abutments and at all three locations (P < .001). Group B yielded dies with minimal gaps compared to groups A and C. The two-step impression technique with 2-mm relief was the most accurate regarding the crucial clinical factor of marginal fit. PMID:23342356

Nissan, Joseph; Rosner, Ofir; Bukhari, Mohammed Amin; Ghelfan, Oded; Pilo, Raphael

2013-01-01

7

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

PubMed

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

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

2011-02-01

8

Good Impressions.  

ERIC Educational Resources Information Center

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

Banks, Geraldine; Pulsifer, Mary

1986-01-01

9

Polyimides containing pendent siloxane groups  

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

10

First Impressions.  

ERIC Educational Resources Information Center

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…

Coen, Frank

1969-01-01

11

Acetylene-Terminated Polyimide Siloxanes  

NASA Technical Reports Server (NTRS)

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

St. Clair, Terry L.; Maudgal, Shubba

1987-01-01

12

Dinosaur Impressions  

NASA Astrophysics Data System (ADS)

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).

Taquet, Philippe

1998-09-01

13

Siloxane-grafted membranes  

DOEpatents

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

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

1989-10-31

14

Siloxane-grafted membranes  

DOEpatents

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.

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

1989-01-01

15

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

NASA Astrophysics Data System (ADS)

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

Subeihi, Haitham

16

Impressive Impact  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2005-01-01

17

Silicon-Phthalocyanine-Siloxane Polymers.  

National Technical Information Service (NTIS)

The invention pertains generally to inorganic polymer synthesis, and in particular to highly thermally stable silicon containing thermoplastic polymers. A number of modified siloxane polymers have been prepared. Although polymers based on poly(dimethyl si...

K. J. Wynne J. Davidson

1978-01-01

18

Removal of siloxanes in biogases.  

PubMed

Methods for the removal of gaseous silicon compounds in biogases are presented. In laboratory studies, various solid adsorption materials and liquid absorption solutions were evaluated for their siloxane elimination efficiencies. Among the liquid sorbents studied, concentrated nitric acid and sulfuric acid were found to be especially potent siloxane removing agents at elevated temperature. Solid adsorbents tested include activated charcoal, carbopack B, Tenax TA, XAD II resins, molecular sieve 13X and silica gel. Apart from activated charcoal, silica gel showed especially high adsorption capacities of more than 100mg/g for siloxanes. Furthermore, excellent thermal regeneration of the loaded material was possible. The efficiency of silica gel in removing gaseous siloxanes was verified at a sewage treatment plant, where an adsorption bed with silica gel was used for biogas drying. Other gas pretreatment installations studied included refrigeration condensers and adsorbent beds of meadow ore for the catalytic removal of hydrogen sulfide. In contrast to biogas drying by refrigeration, which had a poor effect on siloxane content, the installation of meadow ore adsorption beds resulted in a significant siloxane reduction of 31-75%, depending on the site studied. PMID:11348731

Schweigkofler, M; Niessner, R

2001-05-30

19

Depolarized Rayleigh spectra of siloxane polymers  

Microsoft Academic Search

We report measurements of depolarized Rayleigh spectra IVH(?) of polyphenylmethyl siloxane (polymer A) in bulk and in carbon tetrachloride, of polydimethylphenylmethyl siloxane (copolymer B) in bulk, and of depolarized Rayleigh intensity IVH of polydiphenyl siloxane in carbon tetrachloride. From the temperature dependence and the concentration dependence of IVH, we were able to determine positive intermolecular and intramolecular static pair correlations

Y.-H. Lin; G. Fytas; B. Chu

1981-01-01

20

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.

21

Siloxane materials for optical applications  

NASA Astrophysics Data System (ADS)

Siloxanes, which can be viewed as hybrids of glass and organic materials, have been used to fabricate polymer waveguides and devices that exploit the large thermo-optical effect of this material. Siloxanes have many unique properties including good thermal stability, chemical resistance, tunable refractive index, tunable mechanical properties and excellent photo-stability. The refractive index of siloxane polymer is composition dependent and generally ranges from 1.4 to 1.54. Introduction of porosity or composition modification can further expand refractive index range to 1.15~1.63. The loss and absorption characteristics for a variety of silicone-based polymers are examined and an example of a UV curable polymer coating illustrates the flexibility of the silicone polymer family to be tailored to meet specific application needs.

Su, Kai; DeGroot, Jon V., Jr.; Norris, Ann W.; Lo, Peter Y.

2006-01-01

22

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Siloxane modified alumina nanoparticles (generic). 721.10120...Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a...identified generically as siloxane modified alumina nanoparticles (PMN P-05-687)...

2013-07-01

23

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Siloxane modified alumina nanoparticles (generic). 721.10120...Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a...identified generically as siloxane modified alumina nanoparticles (PMN P-05-687)...

2009-07-01

24

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Siloxane modified alumina nanoparticles (generic). 721.10120...Substances § 721.10120 Siloxane modified alumina nanoparticles (generic). (a...identified generically as siloxane modified alumina nanoparticles (PMN P-05-687)...

2010-07-01

25

Conjunctival impression cytology.  

PubMed

A new technique is presented using impression of the conjunctiva with a plastic device to study the conjunctival response in various conjunctival disease states. When used with a rapid acting stain the impression technique proved to be accurate, reproducible, and nondestructive when compared to the standard spatula scraping of the conjunctiva using Giemsa stain. PMID:192184

Thatcher, R W; Darougar, S; Jones, B R

1977-04-01

26

[Impression technics in implantology].  

PubMed

The implant-borne prostheses have become an integral part of the oral rehabilitation procedures. The aim of this article is to describe the most current impression techniques for oral implant prosthetics used at the University of Liège, Belgium. Impression protocols adapted to various prosthetic procedures are described step-by-step through several clinical cases. Emphasis is put on the means necessary for achieving a precise adaptation and a passive fit of the final prosthetic suprastructure. PMID:16193852

Vanheusden, A

2001-01-01

27

Siloxane containing polyimides with improved processability  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

28

How the adoption of impression management goals alters impression formation.  

PubMed

Five experiments (N = 390) tested the hypothesis that adopting an impression management goal leads the impression manager to view an interaction partner as having less of the trait he or she is attempting to express. This hypothesis was confirmed for the impression management goals of appearing introverted, extraverted, smart, confident, and happy. Experiment 2 shows that adoption of the impression goal could alter judgments even when participants could not act on the goal. Experiment 3 provides evidence that adopting an impression management goal prompted a comparison mind-set and that this comparison mind-set activation mediated target judgments. Experiment 4 rules out a potential alternative explanation and provides more direct evidence that comparison of the impression manager's self-concept mediates the impression of the target. Experiment 5 eliminates a potential confound and extends the effect to another impression goal. These experiments highlight the dynamic interplay between impression management and impression formation. PMID:20921279

Gibson, Bryan; Poposki, Elizabeth M

2010-11-01

29

Virtual First Impressions  

ERIC Educational Resources Information Center

Frequently, a nurse's first and only contact with a graduate school, legislator, public health official, professional organization, or school nursing colleague is made through e-mail. The format, the content, and the appearance of the e-mail create a virtual first impression. Nurses can manage their image and the image of the profession by…

Bergren, Martha Dewey

2005-01-01

30

Airbag Impressions in Soil  

NASA Technical Reports Server (NTRS)

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

2004-01-01

31

TOWARD MINIMALLY ADHESIVE SURFACES UTILIZING SILOXANES  

EPA Science Inventory

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

32

Siloxane-Based Surfactants Containing Tromethamol Units  

Microsoft Academic Search

New siloxane-based amphiphilic compounds (a dimer and two copolymers with pendant functional groups) have been synthesized starting from tris(hydroxymethyl)aminomethane (tromethamol) and glycidyl-functionalized siloxane precursors. They have been characterized by spectroscopic methods (Fourier transform infrared (FTIR) spectroscopy and H-nuclear magnetic resonance (NMR)) and their surface properties have been investigated by tensiometry. Surfactant behavior in water (for the dimer and a copolymer

Carmen Racles

2010-01-01

33

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

34

Novel Application of Vermiculite for Siloxane Removal from Biogas  

Microsoft Academic Search

The application of biogas in powering microturbines, gas turbines, and fuel cells calls for low levels of siloxanes in biogas. At present, the generated biogas is filtered with activated carbon filter to remove siloxane prior to power generation application. This paper will report the novel application of vermiculite for siloxane removal from biogas. In adsorption studies conducted with untreated biogas

Nadim Khandaker; Peter Seto

2010-01-01

35

Self-assembling particle-siloxane coatings for superhydrophobic concrete.  

PubMed

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

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

2013-12-26

36

Evidence for a sedimentary siloxane horizon  

SciTech Connect

Selected samples from two Puget Sound sediment cores have been analyzed for poly(organo)siloxanes(silicones). One core was 60 years old at 30-cm depth (ages by lead-210 dating) and showed no evidence for silicones there. The second, 15 years old at depth, exhibited silicones at depth. Clearly shown is evidence for a siloxane horizon in theses two cores, with the presence of the horizon directly related to the fact that silicones have been in widespread use only since World War II. All samples were analyzed by solvent extraction and diffuse reflectance Fourier transform infrared spectrometry. 10 references, 2 figures, 1 table.

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

1986-07-01

37

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

38

Siloxane treatment by adsorption into porous materials  

Microsoft Academic Search

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

D. Ricaurte Ortega; A. Subrenat

2009-01-01

39

Making a Great First Impression  

ERIC Educational Resources Information Center

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

Evenson, Renee

2007-01-01

40

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

41

Energy use of biogas hampered by the presence of siloxanes  

Microsoft Academic Search

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

Raf Dewil; Lise Appels; Jan Baeyens

2006-01-01

42

PREPARATION AND EVALUATION OF FCC CATALYST MODIFIED WITH PURE SILOXANES AND SILOXANES IN SOLUTION OR EMULSION  

Microsoft Academic Search

In the present work a modification in the FCC catalyst formulation was proposed by adding siloxanes to its formulation. Besides improving its mechanical resistance, it also led to an increase in the accessibility index. FCC catalysts were prepared in the plant pilot of Petrobras\\/Cenpes, using a high accessibility technology. The samples were modified with poly-dimethylsiloxane (PDMS), poly- methylphenylsiloxane (PMPS) and

A. F. Costa; J. C. Pinto

43

Discoloration of Polyvinyl Butyral  

NASA Technical Reports Server (NTRS)

Report presents results of study of discoloration in polyvinyl butyral (PVB). Clear PVB gradually turns yellowish brown in simulated-aging tests and outdoor environmental tests. Discoloration severely reduces solar-cell output. Using methods of modern analytical chemistry - transmission absorption, Fourier transform infrared absorption, atomic absorption spectroscopy, and scanning-electron microscopy - study uncovered major cause of yellowing.

Kim, Q.; Shumka, A.

1986-01-01

44

Light-induced diffusion and desorption of alkali metals in a siloxane film: Theory and experiment  

NASA Astrophysics Data System (ADS)

The light-induced desorption and diffusion of alkali-metal atoms in organic films are interesting fields of investigation. An impressive demonstration is given by the recently observed light-induced atomic desorption (LIAD) effect, where a huge alkali-metal atom desorption from siloxane films, previously exposed to atomic vapors, is induced by weak and nonresonant light. In this paper, experimental data and a one-dimensional theoretical model of the effect are presented. The model gives a good description of the vapor density dynamics by taking into account both the atomic diffusion inside the coating and the surface desorption. General equations are reported and discussed within the limits of experimental interest. The potential barrier at the vapor-surface interface and the activation energy for Rb in (poly)dimethylsiloxane have been determined.

Atutov, S. N.; Biancalana, V.; Bicchi, P.; Marinelli, C.; Mariotti, E.; Meucci, M.; Nagel, A.; Nasyrov, K. A.; Rachini, S.; Moi, L.

1999-12-01

45

[Impressions in removable partial dentures].  

PubMed

The success of a removable partial denture, the comfort for the patient, stability and especially the psychological acceptance depend on a series of essential technicals factors. Probably the more delicate stage of the prosthetic technology is the transfer of informations from the mouth of the patient to the prothesist through the impression. In removable partial denture, impression have to take account into the balance between uncompressible hard tissue and soft structures with variable compressibilities. The diversity of clinical cases is responsible for a large diversity of techniques. The aim of this article is to describe the more common technics used in every day practice. PMID:16193853

Prapotnich, R; Domken, O

2001-01-01

46

Siloxane head groups and spacers in calamitic liquid crystals  

NASA Astrophysics Data System (ADS)

Organo-siloxanes are a compromise between a low molar mass liquid crystal and a liquid crystalline side chain polysiloxane polymer. Like polymers the compounds segregate in mesogen rich layers and siloxane rich layers, but like low molar mass compounds the viscosity is in the magnitude of classic LMM liquid crystals. The siloxane group can be used as a head group, a linear linking group and a cyclic linking group. Up to four mesogens can be connected. In the present work small siloxane groups were grafted onto a variety of mesogens in a variety of sizes and shapes. As a steroidal mesogen cholestanol derivatives, as aromatic cores laterally substituted biphenyl benzoates were synthesised and characterised. All liquid crystals investigated were synthesised via established procedures. Olefinic terminated precursor compounds were hydrosilylated with smaller siloxane groups. Structure and phase properties were determined via optical microscopy, differential scanning microscopy, X-ray diffraction and dilatometry. The helielectric compounds were also characterised electro-optically, i.e. tilt angle, spontaneous polarisation and optical response time. To investigate the role of the siloxane in steroidal liquid crystals three different series of cholestanol derivatives were synthesised and characterised. The mesophase behaviour depended strongly on the spacer length, the number of mesogens attached to the siloxane group and the siloxane length. Mono- and bimesogenic compounds exhibited an odd-even effect on the melting transition, whereas the clearing temperatures increased with an increase in spacer length. All LMM organo- siloxanes are liquid crystalline at ambient temperature. The analogous side chain polysiloxanes exhibited significantly higher transition temperatures and viscosity. A series of androstane derivatives revealed the importance of a short branched alkyl tail for the occurance of a broad mesophase. Biphenyl benzoates are known to exhibit ferroelectric mesophases. In several series of organo-siloxanes the role of the spacer, the siloxane moiety and the laterally attached halogen was investigated. The minimum spacer length for ferroelectric phases is 8 methylene units. For 11 methylene units unusual temperature independent phase properties are found. Monomesogens are ferroelectric over large temperature ranges with high tilt angles of up to 45o. All monomesogens are switching in ten's of ?s. Trisiloxane bimesogens are antiferroelectric over a temperature range of up to 60oC. Further anantiferroelectric phases was only found for a fluoro substituted bimesogenic pentasiloxane. In bimesogens a more temperature dependent behaviour was found. Tilt angle and Ps was in the majority of compounds very high. The siloxane group exhibited a possible odd-even effect. Even numbered siloxane moieties caused a significantly lower Ps and tilt. Switching times were slower than analogous monomesogen but still in the magnitude of classic low molar mass ferroelectrics. The siloxane built in all cases siloxane rich layers. For siloxane groups above two units, a linear dependence of the layer distance on the siloxane amount was determined. Cyclotetrasiloxane derivatives exhibited also high tilt angle and large Ps. Switching times were dependent on the lateral substituent. In general the role of the siloxane depends on the mesogen. For steroidal mesogen an impact on the transition temperatures were found. In smectogens an influence on the phase structure and the helielectric properties was detected.

Kloess, Petra Sabine

47

Deciphering indented impressions on plastic.  

PubMed

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

Brown, Sharon; Klein, Asne; Chaikovsky, Alan

2003-07-01

48

Ultrahigh molecular weight aromatic siloxane polymers  

NASA Technical Reports Server (NTRS)

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.

Ludwick, L. M.

1982-01-01

49

Removal of siloxane from digestion gas of sewage sludge  

Microsoft Academic Search

This paper studies the way to remove siloxanes from digestion gas of sewage sludge by adsorbents. Many adsorbents were tested by using the model gas of siloxane in nitrogen. The adsorption ratio was 0.056–0.192 for the activated carbons, 0.004–0.077 for the molecular sieve and 0.104 for the silica gel. An observed tendency was that the activated carbons showed high adsorption

Toru Matsui; Shigeru Imamura

2010-01-01

50

Keeping up impressions: Inferential rules for impression change across the Big Five  

Microsoft Academic Search

Not all first impressions have equal longevity. Which kinds of impression have the greatest mobility—downward and upward—over the course of acquaintanceships? In this article, we propose an inferential account of impression maintenance across Big Five trait domains. With data from field and laboratory studies, we provide evidence that positive impressions of agreeableness (A), conscientiousness (C), and emotional stability (ES) are

Lara K. Kammrath; Daniel R. Ames; Abigail A. Scholer

2007-01-01

51

Vinyl Polysiloxane Impression Material in Removable Prosthodontics Part 1: Edentulous Impressions C E 2  

Microsoft Academic Search

Recent advances in impression materials and stock edentulous impression trays have resulted in simplified approaches to impression making in removable prosthodontics. Once considered an absolute necessity, it is now possible to avoid the need for custom impression trays. In an effort to achieve reliable master casts in a single appointment, new and innovative procedures are now available. This article, the

Joseph J Massad

2007-01-01

52

Removal of siloxane from digestion gas of sewage sludge.  

PubMed

This paper studies the way to remove siloxanes from digestion gas of sewage sludge by adsorbents. Many adsorbents were tested by using the model gas of siloxane in nitrogen. The adsorption ratio was 0.056-0.192 for the activated carbons, 0.004-0.077 for the molecular sieve and 0.104 for the silica gel. An observed tendency was that the activated carbons showed high adsorption ratio, and that the adsorption ratio was increased when BET surface area was higher, and the pore volume was higher and the pH value was higher. Finally, we found a few kinds of activated carbons with the superior ability of adsorption, and we tested the ability of them by using the real digestion gas. All of the siloxanes were found to be removed in the 1000 h test. PMID:19539462

Matsui, Toru; Imamura, Shigeru

2010-01-01

53

Methyl modified siloxane melting gels for hydrophobic films  

Microsoft Academic Search

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

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

2010-01-01

54

Polyether modified siloxanes as electrolyte additives for rechargeable lithium cells  

Microsoft Academic Search

Influence of four poly-ether modified siloxanes as electrolyte additives on charge–discharge cycling properties of lithium was examined. As siloxanes, diethylene glycol methyl-(3-dimethyl(trimethylsiloxy)silyl propyl)ether (sample A), diethylene glycol methyl-(3-dinethyl(trimethylsiloxy)silyl propyl)-2-methylpropyl ether (sample B), diethylene glycol methyl-(3-bis(trimethylsiloxy)silyl propyl)ether (sample C) and diethylene glycol-(3-methyl-bis(trimethylsiloxy)silyl-2-methylpropyl)ether (sample D) were investigated. As a base electrolyte solution, 1M (M, molL?1) LiPF6-ethylene carbonate (EC)\\/methylethyl carbonate (MEC) (mixing volume

Tsuyoshi Inose; Satoru Tada; Hideyuki Morimoto; Shin-ichi Tobishima

2006-01-01

55

Ecotoxicity of siloxane D5 in soil.  

PubMed

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

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

2012-03-01

56

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

PubMed

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

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

2013-12-01

57

Favorable Impression Characteristics of the Recruitment Interviewer.  

ERIC Educational Resources Information Center

This study attempted to assess the effects of three variables: recruiter's age, title, and presentation, on students' impressions of campus job recruiters. A three factor analysis of variance indicated that title and age significantly influenced impressions, while nonfluent presentation may have had a selective effect. (Author/SJL)

Rogers, Donald P.; Sincoff, Michael Z.

1978-01-01

58

Impression materials: a comparative review of impression materials most commonly used in restorative dentistry.  

PubMed

Impression materials are used to record intraoral structures for the fabrication of definitive restorations. Accurate impressions are necessary for construction of any dental prosthesis. The relationship between static and mobile oral structures must be reproduced accurately for an optimum cast. The more common types of impressions are used for fabricating diagnostic and master casts. Accurate impressions depend on identifying the applications that do or do not fit each material's characteristics. Materials used without adequate knowledge of their characteristics can impair a successful outcome. Often, the choice of impression materials depends on the subjective choice of the operator based on personal preferences and past experience with particular materials. PMID:17586147

Rubel, Barry S

2007-07-01

59

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

NASA Technical Reports Server (NTRS)

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.

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

1986-01-01

60

Functionalized polysilalkylene siloxanes (polycarbosiloxanes) by hydrosilylation—Catalysis and synthesis  

Microsoft Academic Search

Polysilalkylene siloxanes or ‘hybrid silicones’ are a comparatively new class of polymeric materials combining the chemical properties of silicones and paraffins in a unique way. They can be used as elastomers with remarkable thermal stability and chemical resistance, as wetting agents, surfactants, and hydrophobic coatings.Catalytic hydrosilylation provides a convenient route for the synthesis of these new functional materials. Suitable ?,?-Si–H

Sophie Putzien; Oskar Nuyken; Fritz E. Kühn

2010-01-01

61

21 CFR 872.3670 - Resin impression tray material.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Resin impression tray material. 872.3670...DEVICES Prosthetic Devices § 872.3670 Resin impression tray material. (a) Identification. Resin impression tray material is a device...

2013-04-01

62

21 CFR 872.3670 - Resin impression tray material.  

...2014-04-01 2014-04-01 false Resin impression tray material. 872.3670...DEVICES Prosthetic Devices § 872.3670 Resin impression tray material. (a) Identification. Resin impression tray material is a device...

2014-04-01

63

21 CFR 872.3670 - Resin impression tray material.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Resin impression tray material. 872.3670...DEVICES Prosthetic Devices § 872.3670 Resin impression tray material. (a) Identification. Resin impression tray material is a device...

2010-04-01

64

21 CFR 872.3670 - Resin impression tray material.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Resin impression tray material. 872.3670...DEVICES Prosthetic Devices § 872.3670 Resin impression tray material. (a) Identification. Resin impression tray material is a device...

2012-04-01

65

21 CFR 872.3670 - Resin impression tray material.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Resin impression tray material. 872.3670...DEVICES Prosthetic Devices § 872.3670 Resin impression tray material. (a) Identification. Resin impression tray material is a device...

2011-04-01

66

Impression Formation: The Role of Expressive Behavior  

Microsoft Academic Search

This research examined the effects of personality\\/social skills and individual differences in expressive style on impression formation. Particular attention was given to the role of nonverbal behaviors in the formation of initial impressions. Sixty-two subjects were measured on self-report personality and communication skill scales, on posed emotional sending ability, and on physical attractiveness. Subjects were then videotaped while giving a

Ronald E. Riggio; Howard S. Friedman

1986-01-01

67

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

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Siloxanes and silicones, Me hydrogen, reaction products with...Substances § 721.6170 Siloxanes and silicones, Me hydrogen, reaction products with...substance identified as siloxanes and silicones, Me hydrogen, reaction...

2009-07-01

68

Method for the recycling of polyvinyl butyral  

US Patent & Trademark Office Database

Method for the recycling of polyvinyl butyral based on obtaining recycled polyvinyl butyral (PVB) from laminated glass which is shattered and the polyvinyl butyral (PVB) is separated. The sheet obtained is cut into pieces and cleaned to eliminate dirt and foreign matter. The solid state PVB is subjected to a first polyvinyl butyral (PVB) purification stage with a chemical treatment with a first reagent and a final chemical treatment with a second reagent. The obtained purified polyvinyl butyral is suitable to be used in the manufacture of laminated glass.

2013-09-10

69

Block copolymers of polystyrene and side-chain liquid crystalline siloxanes: morphology and thermal properties  

Microsoft Academic Search

Well-defined diblock copolymers of polystyrene and smectic side-chain liquid crystalline siloxanes have been prepared with a wide range of molecular weights (Mn total from 20,000 to 165,000) and liquid crystalline siloxane weight fractions (0.4–0.91). Two different types of block copolymers were examined, each series having a different mesogen attached to the siloxane block. Increasing the rigidity of the mesogen led

Aaron Moment; Paula T Hammond

2001-01-01

70

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

Microsoft Academic Search

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

Rene Huppmann; Horst Werner Lohoff; Horst Friedrich Schröder

1996-01-01

71

Ultra-high molecular weight silphenylene-siloxane polymers  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

72

Ultra-High-Molecular-Weight Silphenylene/Siloxane Elastomers  

NASA Technical Reports Server (NTRS)

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.

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

1989-01-01

73

Photosensitive crown ether–siloxane copolymers bearing azobenzene chromophores  

Microsoft Academic Search

This paper presents the synthesis procedure of new photosensitive siloxane–crown ether copolymers using the polycondensation reaction of an oligosiloxane with COCl end groups and bisazo derivatives of dibenzo-18-crown-6 polyether. The azodiphenol compounds were prepared via the coupling reaction of 4,4?-diamine-DB18C6 diazonium salt with phenol or 1-naphthol. The polymers were characterized by IR absorption and 1H-NMR spectra as well as by

Rodinel Ardeleanu; Anton Airinei; Gabriela Sacarescu; Liviu Sacarescu

2002-01-01

74

Siloxane-containing polymer matrices as coating materials  

Microsoft Academic Search

Coating materials based on siloxane-containing polymer matrices that had been modified with fluoropolymer or acrylic resins\\u000a and applied as organic components of hybrid systems were examined. The optimal recipes of the dispersion systems, applied\\u000a as polymer matrix precursors, were determined on the basis of factorial experiments, designed as 22 with additional ‘star’ experimental points to obtain greater accuracy in the

M. Zielecka; E. Bujnowska; K. Bajdor

2007-01-01

75

Banana?shaped side chain liquid crystalline siloxanes  

Microsoft Academic Search

Eight banana?shaped side chain liquid crystalline oligomers and polymers have been synthesized by hydrosilylation of vinyl?terminated bent?core mesogens with trimethylsilyl?terminated siloxanes. The synthesized oligomers and polymers, and their olefinic precursors, were investigated by polarizing optical microscopy (POM), differential scanning calorimetry, X?ray diffraction (XRD), electro?optical experiments and Maldi?Tof. The short?tailed olefins form a Colr mesophase, whereas those with longer chains exhibit

Remko Achten; Arie Koudijs; Marcel Giesbers; R. Amaranatha Reddy; Ton Verhulst; Carsten Tschierske; Antonius T. M. Marcelis; Ernst J. R. Sudhölter

2006-01-01

76

Synthesis and characterization of siloxane-modified epoxy resin  

Microsoft Academic Search

Epoxy resins of the EBS, a bis-p-phenol S modified diglycidyl ether of bis-p-phenol A and the ESBS, a siloxane modified EBS epoxy resin were prepared. Both structures of EBS and ESBS were elucidated with IR,1H NMR, and13C NMR. The near perpendicular comformation of two phenyl rings of sulfone has been introduced into the epoxy resins of EBS und ESBS for

Shyue-Tzoo Lin; Steve K. Huang

1994-01-01

77

Mg 2+-doped poly(?-caprolactone)\\/siloxane biohybrids  

Microsoft Academic Search

Ionically conducting materials based on a poly(?-caprolactone) (PCL)\\/siloxane organic\\/inorganic host framework doped with magnesium triflate (Mg(CF3SO3)2) were synthesized by the sol–gel process. In this matrix short PCL chains are covalently bonded to the siliceous network via urethane linkages. In this study the salt content of samples was identified using the conventional notation n, where n indicates the number of (C(O)(CH2)5O)

J. C. S. Teixeira; M. Fernandes; V. de Zea Bermudez; P. C. Barbosa; L. C. Rodrigues; M. M. Silva; M. J. Smith

2010-01-01

78

Siloxane removal from biogas by biofiltration: biodegradation studies  

Microsoft Academic Search

Recently a lot of attention has been focused on volatile methyl siloxanes (VMSs) in biogas because of the costly problems\\u000a deriving from the formation of silicate-based deposits in biogas-fuelled power plant equipments. Currently, VMSs are removed\\u000a from biogas with high operational costs by adsorption on activated carbons. Biofiltration could be a cost-effective and environmentally\\u000a friendly alternative to current technologies, leading

Francesca Accettola; Georg M. Guebitz; Rainer Schoeftner

2008-01-01

79

Siloxanes removal from biogas by high surface area adsorbents.  

PubMed

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

Gislon, P; Galli, S; Monteleone, G

2013-12-01

80

A self-healing poly(dimethyl siloxane) elastomer  

Microsoft Academic Search

In this work, self-healing functionality is imparted to a poly(dimethyl siloxane) (PDMS) elastomer with low modulus and high strain-to-failure behavior. This material utilizes a two-microcapsule system to provide a mechanism for autonomic repair of damage. One microcapsule type contains a functionalized high-molecular-weight resin and organometallic catalyst compounds. The second microcapsule type contains a functional copolymer (initiator) that facilitates the crosslinking

Michael Wade Keller

2007-01-01

81

Novel Low-Temperature Poss-Containing Siloxane Elastomers  

NASA Technical Reports Server (NTRS)

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.

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

2008-01-01

82

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

PubMed Central

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.

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

2012-01-01

83

How To Achieve Better Impressions in Computer-Mediated Communication?  

ERIC Educational Resources Information Center

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

Liu, Yuliang; Ginther, Dean

84

Accuracy of three implant impression techniques with different impression materials and stones.  

PubMed

The purpose of this study was to compare the accuracy of casts made using three different impression techniques to obtain an accurate definitive cast for fabrication of multiple-implant prostheses. Twelve experimental groups were formed combining the following conditions: three impression techniques, two impression materials, and two cast materials. The main effects of the three factors were analyzed by three-way analysis of variance using the full factorial general linear model between factors. The results showed that there were no significant differences in mean values for the transferred dimensions between the control and experimental groups. None of the measurements in the horizontal plane of the definitive casts demonstrated significant differences among the impression techniques with different impression and cast materials (P > .01). PMID:22259795

Chang, Won-Gun; Vahidi, Farhad; Bae, Kwang-Hak; Lim, Bum-Soon

2012-01-01

85

[Impression materials. Dimensional stability after pouring].  

PubMed

The Authors wanted to establish which could be for every impression material tested, the most favourable moment for the development of plaster models in a steady environment conditions of temperature and relative humidity. From the analysis of the results obtained, we can clearly conclude that every material examined offers an ideal time interval in which we have to cast the model in plaster. This study aspires to be an invitation to all operator in the sector, to repeat this experience in their work environment to know and better manage the procedures and the materials used, from the taking the impression to the executing of the plaster model. PMID:1824363

Barlattani, A; Ottria, L; Gargari, M; Condò, S

1991-09-15

86

Impression Testing of Self-Healing Polymers  

NASA Technical Reports Server (NTRS)

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.

Hinkley, Jeffrey A.; Huber, Amy

2005-01-01

87

[Digital implant impression taking - an overview].  

PubMed

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

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

2014-01-01

88

Polyvinyl Esters of Omega-H-Perfluoroacids and Polyvinyl Alcohol Obtained from Them,  

National Technical Information Service (NTIS)

By means of radical polymerization at 20 we obtained polyvinyl esters of omega-H-perfluoroacids from monomers. The product of their saponification - polyvinyl alcohol (PVA) - differs significantly from PVA which is obtained by other methods (mainly with r...

Y. N. Rostovskiy L. D. Budovskaya

1987-01-01

89

Research and Development of Impression Evidence.  

National Technical Information Service (NTIS)

The collection and preservation of tool mark and impression evidence is an important part of the field of criminalistics. The ability to discern class and individual characteristics and use these to either identify or exclude an item as a possible match i...

A. Dale D. Athanasopoulos E. Sorrentino

2013-01-01

90

Additivity of Clothing Cues in First Impressions.  

ERIC Educational Resources Information Center

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

Lennon, Sharron J.

1986-01-01

91

Project MATCH Client Impressions About Alcoholics Anonymous  

Microsoft Academic Search

Alcoholics Anonymous (AA) is the most popular mutual-help program for individuals with alcohol-related problems, and most treatment programs encourage AA attendance during and after treatment. As part of a larger study (Project MATCH, 1997; 1998), this study examined aftercare (n = 621) and outpatient (n = 415) client subjective impressions about AA. As predicted, client ratings of the helpfulness of

J. Scott Tonigan; William R. Miller; Gerard J. Connors

2000-01-01

92

Determination of siloxanes in silicone products and potential migration to milk, formula and liquid simulants.  

PubMed

A pressurised solvent extraction procedure coupled with a gas chromatography-mass spectrometry-selective ion monitoring (GC-MS-SIM) method was developed to determine three cyclic siloxanes, octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6) and three linear siloxanes, octamethyltrisiloxane (L3), decamethyltetrasiloxane (L4), dodecamethylpentasiloxane (L5), in silicone products. Additionally, two different extraction methods were developed to measure these siloxanes migrating into milk, infant formula and liquid simulants (50 and 95% ethanol in water). The limits of quantification (LOQs) of the six siloxanes ranged from 6?ng/g (L3) to 15?ng/g (D6). Silicone nipples and silicone bakewares were extracted using pressurised solvent extraction (PSE) and analysed using the GC-MS-SIM method. No linear siloxanes were detected in the silicone nipple samples analysed. The three cyclic siloxanes (D4, D5 and D6) were detected in all silicone nipple samples with concentrations ranging from 0.5 to 269?µg/g. In the bakeware samples, except for L3, the other five siloxanes were detected with concentrations ranging from 0.2?µg/g (L4) to 7030?µg/g (D6). To investigate the potential migration of the six siloxanes from silicone nipples to milk and infant formula, a liquid extraction and dispersive clean-up procedure was developed for the two matrices. The procedure used a mix of hexane and ethyl acetate (1?:?1, v/v) as extraction solvent and C?? powder as the dispersive clean-up sorbent. For the liquid simulants, extraction of the siloxanes was achieved using hexane without any salting out or clean-up procedures. The recoveries of the six siloxanes from the milk, infant formula and simulants fortified at 50, 100, 200, 500 and 1000?µg/l ranged from 70 to 120% with a relative standard derivation (RSD) of less than 15% (n?=?4). Migration tests were performed by exposing milk, infant formula and the liquid simulants to silicone baking sheets with known concentrations of the six siloxanes at 40°C. No siloxanes were detected in milk or infant formula after 6?h of direct contact with the silicone baking sheet plaques, indicating insignificant migration of the siloxanes to milk or infant formula. Migration tests in the two simulants lasted up to 72?h and the three cyclic siloxanes were detected in 50% ethanol after an 8-h exposure and after 2?h in 95% ethanol. The highest detected concentrations of D4, D5 and D6 were 42, 36 and 155?ng/ml, respectively, indicating very limited migration of D4, D5 or D6 into the two simulants. PMID:22575024

Zhang, Kai; Wong, Jon W; Begley, Timothy H; Hayward, Douglas G; Limm, William

2012-08-01

93

Development of on-line measurement techniques for siloxanes and other trace compounds in biogas.  

PubMed

This paper focuses on the development of an on-line measurement method for siloxanes and other biogas trace compounds impeding the energy utilisation of biogas, as well as the main gas components, methane and carbon dioxide. The method is based on gas chromatography and FT-IR-analysis. The level of siloxane, hydrogen sulphide and halogens in biogas generated in a number of landfills and digesters in Finland is also presented and factors affecting the concentrations discussed. Generally, the level of biogas trace compounds hampering electricity production was lower than those measured at comparable sites in Central Europe and the US. Moreover, the paper discusses the significance of on-line monitoring of siloxane in connection to biogas-to-electricity applications and points out with activated carbon as an example the benefits of on-line siloxane measurement in the control of siloxane removal technology. PMID:20056535

Arnold, M; Kajolinna, T

2010-06-01

94

Mass spectra of linear and branched methyl(vinyl)siloxanes  

Microsoft Academic Search

The mass spectra of some linear and branched methyl(vinyl)siloxanes Me3SiOSi(Me)(R)(OSiMeVin)\\u000a n\\u000a Y (R=Vin, OSiMe3; Y=OSiMe3, Cl;n=0–2) were studied. The regularities of their fragmentation and an anomalously high probability of elimination of the ethylene\\u000a molecule to form the stable 1,3-dioxa-2,4,6-trisilacyclohexane skeleton were revealed.

M. G. Voronkov; L. V. Klyba; S. V. Basenko; R. G. Mirskov; V. N. Bochkarev

1999-01-01

95

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

NASA Astrophysics Data System (ADS)

Siloxanes have been extensively used as additives to modulate surface properties such as surface tension, hydrophobicity/hydrophobicity, and adhesion, etc. Although, polydimethyl -siloxane and polydiphenylsiloxane are the most commonly used siloxanes, the properties are at extremes in terms of glass transition temperature and flexibility. It is proposed that the ability to control the properties in between the these extremes can be provided by cycloaliphatic substitutions at the siloxane backbone. It is expected that this substitution might work due to the intermediate backbone rigidity. In order to achieve the above objectives, a synthetic route was developed to prepare cycloaliphatic (cyclopentane and cyclohexane) silane monomers followed by subsequent polymerization and functionalizations to obtain glycidyl epoxy, aliphatic amine and methacrylate telechelic siloxanes. The siloxanes were either thermally or UV-cured depending on end functionalizations. Chemical characterization of monomers, oligomers and polymers were performed using 1H, 13C, 29Si-NMR, FT-IR and GPC. The curing kinetics of photo-induced reactions were investigated through photo-differential scanning calorimetry (PDSC). The oxygen permeability, mechanical, coatings, and release properties of siloxanes were studied as a function of the backbone substitutions. The mechanical, coatings and released properties of cycloaliphatic siloxanes improved with respect to polydimethylsiloxanes. The thermal analysis of the cured films were carried out using differential scanning calorimetry (DSC). Viscoelastic properties of the cured siloxanes due to the variation of substitution at the siloxane backbone were measured using dynamic mechanical thermal analysis (DMTA). The cycloaliphatic substituted siloxanes showed an increased glass transition temperature and permeability but reduced crosslink density, conversion, and rate of curing with respect to polydimethylsiloxanes. Hybrids of siloxanes were prepared with linseed oil based alkyds to study the effect of variation of alkyd oil lengths and cycloaliphatic substitutions on siloxane backbone. The oil length of an alkyd resin is defined as the number of grams of oil used to produce 100 grams of resin. Three linseed oil based alkyds representing long, medium, and short oil lengths were grafted with siloxanes substituted with methyl, cyclopentyl, and cyclohexyl groups. The reaction was monitored through FTIR and 1H-NMR. The hybrids were formulated with standard drier package and thermally cured for detailed film characterization. Improvement in crosslink density, flexibility, and reverse impact resistance were found as function of oil length. However, tensile modulus, elongation, glass transition temperature, drying time and fracture toughness decreased with increase in oil length. For hybrids, the cycloaliphatic substituents at the siloxane backbone showed enhanced mechanical and coating properties as compared to hybrids with polydimethylsiloxanes. Random and block copolymer of polydimethylsiloxanes with polydicycloaliphatic-siloxanes were synthesized and compared with homopolymers of polydicycloaliphatic siloxanes. The chemical characterization of the copolymers and homopolymers were carried out through 1H, 13C, 29Si-NMR, and FT-IR. The glass transition temperatures (Tg) of the synthesized polymers were obtained through DSC and advanced rheometric expansion system (ARES). The Tg of random copolymers were found to be higher than the corresponding block copolymers. There was very small difference in T g between cycloaliphaticsiloxanes homopolymers and corresponding random copolymers. From the above results, it can be inferred that the cycloaliphatic substitutions at the siloxane backbone can be used as a means to obtain properties intermediate to polydimethyl- and polydiphenyl siloxanes.

Chakraborty, Ruby

96

Cellulose whiskers reinforced polyvinyl alcohol copolymers nanocomposites  

Microsoft Academic Search

Nanocomposite materials were prepared from copolymers of polyvinyl alcohol and polyvinyl acetate and a colloidal aqueous suspension of cellulose whiskers prepared from cotton linter. The degree of hydrolysis of the matrix was varied in order to vary the hydrophilic character of the polymer matrix and then the degree of interaction between the filler and the matrix. Nanocomposite films were conditioned

Mehdi Roohani; Youssef Habibi; Naceur M. Belgacem; Ghanbar Ebrahim; Ali Naghi Karimi; Alain Dufresne

2008-01-01

97

[Impression technics in complete removable dentures].  

PubMed

The main objective of a complete removable denture is to re-establish the function and aesthetics that lead to an acceptable soft tissue as well as psychologic integration. The fabrication of complete removable denture is a rather complex procedure being composed of several clinical and laboratory steps. All these steps are interdependant and governed by a certain level of empirism. The impression taking, the first part of the procedure, is crucial for the success of the whole prosthetic rehabilitation. The aim of this article is to describe in detail the impression taking procedures for complete removable dentures, in order to help solve a number of pitfalls encountered in daily clinical practice. PMID:16193854

Domken, O; Chichoyan, F; Prapotnich, R

2001-01-01

98

Polyvinyl alcohol hydrogels for iontohporesis  

NASA Astrophysics Data System (ADS)

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.

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

2013-06-01

99

Resident Documentation of Diagnostic Impression in Sexual Abuse Evaluations  

Microsoft Academic Search

In sexual abuse evaluations, the documentation of the examiner's diagnostic impression is essential. If the diagnostic impression is not documented, the examiner will have to rely on memory rather than the medical record when called to testify. The purpose of this study was to determine whether pediatric residents adequately document their diagnostic impression in child sexual abuse evaluations. We performed

Juan M. Parra; Rebecca L. Huston; D. Michael Foulds

1997-01-01

100

Carbonate-modified siloxanes as solvents of electrolyte solutions for rechargeable lithium cells  

Microsoft Academic Search

Influence of mixing carbonate-modified siloxanes into LiPF6-ethylene carbonate (EC)\\/ethylmethyl carbonate (EMC) (mixing volume ratio=3:7) mixed solvent electrolytes on charge–discharge cycling properties of lithium was examined. As the solute, 1M (M: molL?1) LiPF6 was used. As siloxanes, 4-(2-trimethylsilyloxydimethylsilylethyl)-1,3-dioxolan-2-one and 4-(2-bis(trimethylsilyloxy)methylsilylethyl)-1,3-dioxolan-2-one were investigated. These siloxanes are derivatives of butylene cyclic carbonate or vinyl ethylene carbonate. Charge–discharge cycling efficiencies of lithium metal anodes

Takashi Takeuchi; Satoshi Noguchi; Hideyuki Morimoto; Shin-ichi Tobishima

2010-01-01

101

High temperature impression creep testing of weldments  

SciTech Connect

The impression creep test technique, a modified hot hardness test in which the time dependence of the indentor displacement correlates directly to creep properties, has been utilized to measure the localized creep properties across welded joints. High temperature creep data, as a function of position, with respect to the fusion line, were measured on an autogeneous GTA aluminum weld and on an austenitic stainless steel to ferritic steel dissimilar metal weldment. The creep resistance of the aluminum weld decreased with position on traversing from the solidified weld metal to the base metal, and the variation in creep resistance with position was shown to correlate directly to gradients in microstructure.

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

1985-06-01

102

Observations and impressions from lunar orbit  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

103

Multiband Impressions of Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

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.

Marscher, Alan P.

104

Evaluation of the precision of three implant transfer impression techniques using two elastomeric impression materials.  

PubMed

A master cast representing a completely edentulous mandible was fabricated in polyurethane resin and had four implants secured to the anterior interforaminal area. Impressions were made using six technique-material combinations. Ten definitive casts were fabricated for each technique. Linear distances between implants were measured using a traveling microscope. There was no statistically significant difference between the direct unsplinted and splinted techniques (P > .05), while the indirect technique was statistically significantly different from the other two techniques (P < .05). There was no statistically significant difference between the two impression materials. PMID:21209987

Mostafa, Tamer Mohamed Nasr; Elgendy, Mohamed Nabeel Mohamed; Kashef, Nahed Ahmed; Halim, Maha Mostafa

2010-01-01

105

D2-m-Carborane-Siloxanes. VI. Oxidative Stabilization of Vulcanizates with Ferric Oxide.  

National Technical Information Service (NTIS)

Ferric oxide produced from iron pentacarbonyl was evaluated as an oxidative stabilizer in D2-m-carborane-siloxane and polydimethylsiloxane vulcanizates. The results indicate a significant improvement in efficiency compared to powdered ferric oxide. Thus a...

E. N. Peters D. D. Stewart J. J. Bohan D. W. McNeil

1977-01-01

106

Environmentally friendly antibacterial cotton textiles finished with siloxane sulfopropylbetaine.  

PubMed

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

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

2011-04-01

107

Density Anomalies in Thin Liquid Films of Hydride Functional Siloxanes  

NASA Astrophysics Data System (ADS)

Thin liquid films of polyfunctional poly(methylhydro-dimethyl)siloxane (PMDMS) copolymers adsorbed on polished silicon wafers with a native oxide layer have been investigated using x-ray reflectivity. The liquid density profile in the region next to the substrate is highly sensitive to the molecule-substrate interactions: there is a density ‘dip’ in this region and the amplitude of the dip increases with the fraction of Si-H groups in the PMDMS molecule. The electron density also varies with film thickness. The layering of PMDMS molecules in thin films is similar to that previously reported^1 in PDMS molecules of the same molecular weight. This confinement-induced layering is weak and independent of the fraction of H-containing groups in the PMDMS molecule. ^1G. Evmenenko, S.W. Dugan, J. Kmetko, and P. Dutta, Langmuir 17, 4021 (2001).

Evmenenko, G.; Yu, C.-J.; Kmetko, J.; Dutta, P.

2002-03-01

108

Structure-property relationships in silica-siloxane nanocomposite materials  

SciTech Connect

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

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

1997-03-01

109

Preparation and characterization of a siloxane containing bismaleimide  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

110

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

Microsoft Academic Search

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

Yuichi Horii; Kurunthachalam Kannan

2008-01-01

111

Siloxane-urethane membranes for removal of volatile organic solvents by pervaporation  

Microsoft Academic Search

Aqueous dispersions of siloxane-urethane copolymers (polysiloxaneurethanes) containing 0–49% of siloxane moieties were synthesized by the modified prepolymer-ionomer method. The properties of the dispersions were determined. Dense membranes were prepared from those dispersions by crosslinking with a multifunctional aziridine derivative. The structure of the obtained membranes was investigated by FTIR, solid state 13C NMR, 29Si NMR and DSC. Prepared membranes were

Wojciech Czerwi?ski; Barbara Ostrowska-Gumkowska; Janusz Kozakiewicz; Wojciech Kujawski; Andrzej Warszawski

2004-01-01

112

FourierTransform Infrared Spectroscopy Studies of the Interaction of Functionalized Siloxane Polymers with Porous Silica  

Microsoft Academic Search

Adsorption behavior of the siloxane polymer, cyanopropylmethyl-phenyl-methyl-siloxane, in contact with a mesoporous silica has been investigated by Fourier-transform infrared spectroscopy (FT-IR) using a series of physically modified materials with different coating levels up to 20 w\\/w%. The nitrile stretch bands, which are observed in the 2150–2350 cm1 range, exhibited complex profiles due to a variety of interactions of the cyano

Anima Bose; Roger K. Gilpin; Mietek Jaroniec

2000-01-01

113

On the feasibility of chemical reactions in the presence of siloxane-based surfactants  

Microsoft Academic Search

Siloxane-containing surfactants have been tested as stabilizers for the preparation of polymer nanoparticles by three types\\u000a of chemical reactions. Two crosslinking reactions were used to obtain silicone elastomers particles: one involved HO-terminated\\u000a polydimethylsiloxane and tetraethoxysilane, while the other one was a crosslinking via polyhydrosilylation. The third reaction\\u000a was a linear polycondensation between a diamine and a siloxane dialdehyde. The monitoring

Carmen Racles; Maria Cazacu; Gabriela Hitruc; Thierry Hamaide

2009-01-01

114

Development of on-line measurement techniques for siloxanes and other trace compounds in biogas  

Microsoft Academic Search

This paper focuses on the development of an on-line measurement method for siloxanes and other biogas trace compounds impeding the energy utilisation of biogas, as well as the main gas components, methane and carbon dioxide. The method is based on gas chromatography and FT-IR-analysis. The level of siloxane, hydrogen sulphide and halogens in biogas generated in a number of landfills

M. Arnold; T. Kajolinna

2010-01-01

115

Primary Plasticizers for Poly(Vinyl Chloride).  

National Technical Information Service (NTIS)

According to the patent application, acetal derivatives of polyunsaturated fatty compositions were prepared and found to function as primary plasticizers. Poly(vinyl chloride) resins plasticized by the compositions of this application have properties equa...

R. A. Awl E. H. Pryde

1974-01-01

116

Making the Right Impression: A Field Study of Applicant Impression Management During Job Interviews  

Microsoft Academic Search

Two issues were explored: (a) which impression management (IM) tactics applicants use during actual interviews and (b) whether there is a relationship between applicants' IM tactics and their interview outcomes. The study also examined convergence across different methods and raters when measuring IM. Postinterview survey measures were obtained from applicants and interviewers regarding applicant IM behavior during a specific interview;

Cynthia Kay Stevens; Amy L. Kristof

1995-01-01

117

Electrochemical and thermal stability of a siloxane-based electrolyte on a lithium transition metal oxide cathode  

Microsoft Academic Search

The compounds deposited on a lithium transition metal oxide charged in a siloxane-based electrolyte were analyzed by Fourier transformation infrared (FT-IR) spectroscopy and thermal analysis. The decomposition of the siloxane-based electrolyte occurred at voltages above 4.2V, and the compounds that deposited on the cathode surface consisted of species from both the decomposed siloxane molecule and the electrolyte salt. Differential scanning

Hiroshi Nakahara; Manabu Tanaka; Sang-Young Yoon; Steven Nutt

2006-01-01

118

A novel approach for the preparation of organic-siloxane oligomers and the creation of hydrophobic surface  

Microsoft Academic Search

In this paper, poly(acrylate-g-siloxane) with novel comb-like structure was designed and prepared so as to create a strongly hydrophobic polymer surface. In order to achieve this goal, a series of organic-siloxane oligomers with different chain lengths and a double bond were firstly synthesized through the catalytic reforming and hydrosilylation reaction. Then, poly(acrylate-g-siloxane) was prepared by the copolymerization of the resulting

Baotan Zhang; Bailing Liu; Xiaobo Deng; Shunsheng Cao; Xiaohui Hou; Hualin Chen

2007-01-01

119

Effect of the linear siloxane chain in cyclic silsesquioxane (CSSQ) on the mechanical\\/electrical property of the thin films  

Microsoft Academic Search

Several kinds of cyclic silsesquioxane (CSSQ) precursors containing linear siloxane chain were prepared to improve both the mechanical properties of their thin films and the compatibility with heptakis (2,3,6-tri-O-methyl)-?-cyclodextrin (tCD) as a porogen. The precursors were synthesized using a hydrolysis\\/condensation reaction with 2,4,6,8-tetramethyl-2,4,6,8-tetra (trimethoxysilylethyl) cyclotetrasiloxane (cyclic monomer) and three kinds of linear siloxane monomers. As the linear siloxane chain length

Yi-Yeol Lyu; Jin-Heong Yim; Younghun Byun; Sang-Yun Lee; In-Sun Jung; Lyong Sun Pu

2004-01-01

120

Irradiation of polyvinyl alcohol and polyvinyl pyrrolidone blended hydrogel for wound dressing  

Microsoft Academic Search

Polyvinyl alcohol and polyvinyl pyrrolidone (PVA–PVP) blended hydrogel for wound dressing has been prepared by using gamma rays irradiation technique. The gel fraction, mechanical properties, the water content and water absorption performance of the hydrogels were measured. It was found that the gel fraction increases with increasing irradiation dose but never reaches 100% of gel. The PVA\\/PVP blended hydrogel has

Mirzan T Razzak; Darmawan Darwis; Zainuddin; Sukirno

2001-01-01

121

Motion cues that make an impression?  

PubMed Central

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.

Koppensteiner, Markus

2013-01-01

122

Dimensional stability ofautoclave sterilised addition cured impressions and trays.  

PubMed

The aim of this study was to investigate the dimensional accuracy of impressions following sterilisation by autoclaving. Dental impressions (75) were of a dentoform containing 6 reference points. The impressions were split into 5 groups of 15, each group used a different impression technique. Groups were divided into 3 subgroups with 5 impressions as control, 5 for disinfection by Perform-ID and 5 being autoclaved. Measurements were made using a travelling light microscope. A minimal significant dimensional difference (0.01impression method. No significant dimensional differences were observed for all other groups (P>0.05). The trays and materials tested were suitable for the autoclave sterilisation. PMID:24922998

Deb, S; Etemad-Shahidi, S; Millar, B J

2014-03-01

123

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

PubMed Central

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.

Riemer, Hila; Shavitt, Sharon

2012-01-01

124

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

PubMed Central

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

Holoien, Deborah Son; Fiske, Susan T.

2014-01-01

125

Junge relationships in measurement data for cyclic siloxanes in air.  

PubMed

In 1974, Junge postulated a relationship between variability of concentrations of gases in air at remote locations and their atmospheric residence time, and this Junge relationship has subsequently been observed empirically for a range of trace gases. Here, we analyze two previously-published datasets of concentrations of cyclic volatile methyl siloxanes (cVMS) in air and find Junge relationships in both. The first dataset is a time series of concentrations of decamethylcyclopentasiloxane (D5) measured between January and June, 2009 at a rural site in southern Sweden that shows a Junge relationship in the temporal variability of the measurements. The second dataset consists of measurements of hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and D5 made simultaneously at 12 sites in the Global Atmospheric Passive Sampling (GAPS) network that shows a Junge relationship in the spatial variability of the three cVMS congeners. We use the Junge relationship for the GAPS dataset to estimate atmospheric lifetimes of dodecamethylcyclohexasiloxane (D6), 8:2-fluorotelomer alcohol and trichlorinated biphenyls that are within a factor of 3 of estimates based on degradation rate constants for reaction with hydroxyl radical determined in laboratory studies. PMID:23177712

MacLeod, Matthew; Kierkegaard, Amelie; Genualdi, Susie; Harner, Tom; Scheringer, Martin

2013-10-01

126

Evaluation of accuracy of direct transfer snapon impression coping closed tray impression technique and direct transfer open tray impression technique: an in vitro study.  

PubMed

Accuracy of the implant impression technique is one of the key factor determining the strain free fit of the prosthesis fabricated which influences the treatment success. Two implant impression techniques namely the closed tray technique with transfer coping and open tray technique were evaluated for accuracy with stone casts obtained from them. Casts were evaluated using a custom constructed bar on strain gage (SYSCOM) and abutment coordinates using Coordinate Measuring Machine (TESA micro-HITE). The statistical analysis with one way ANOVA and Mann-Whitney tests show that the casts obtained with open tray technique were accurate than the casts of closed tray technique (significance P < 0.001). Direct transfer impression technique with less number of components ensures the high accuracy of transfer of implant positions from master cast to the laboratory cast compared to the indirect transfer impression technique. PMID:24431738

Balamurugan, T; Manimaran, P

2013-09-01

127

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

PubMed

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

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

2014-08-01

128

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

129

Conjunctival impression cytology: bright hope of children.  

PubMed

A practical method of screening for pre-clinical xerophthalmia due to vitamin A deficiency, called conjunctival impression cytology (CIC), is described as it is being used in a training stage in the Philippines. The noninvasive technic consists of touching the conjunctiva with a filter paper disc, and fixing and staining the disc on a slide for histology. Normally goblet cells with mucin spots are seen among sheets of epithelial cells. In abnormal conjunctiva from vitamin A deficient individuals, the epithelial cells are enlarged, and goblet cells are lacking. These specimens may be obtained from areas of the conjunctiva that appear clinically normal. The equipment needed is millipore paper, a hand-held suction pump with 5 feet of tubing, tissue or gauze, screw-top vials, labels, fixative, Papanicolaou stain, and a microscope. Vitamin A supplements can be given to affected children, or to the whole population at risk. With CIC training materials donated by International Center for Epidemiologic and Preventive Ophthalmology (ICEPO) at the Wilmer Institute, and the School of Hygiene and Public Health of the Johns Hopkins University, Baltimore, the 1st training class was certified by the Nutrition Center of the Philippines. Twice yearly training of physicians and technologists has been recommended. PMID:12284665

1991-01-01

130

Coping With Stereotype Threat: Denial as an Impression Management Strategy  

Microsoft Academic Search

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

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

2005-01-01

131

Interviewers’ Sensitivity to Impression Management Tactics in Structured Interviews  

Microsoft Academic Search

This study examines interviewers’ sensitivity to impression management in structured interviews by determining the relative importance that interviewers attach to (verbal and nonverbal) impression management as compared to the relative importance that they attach to predetermined competencies. Two samples of interviewers (55 Master I\\/O psychology students and 18 professional interviewers) watched and evaluated videotaped interviewees who were instructed to put

Filip Lievens; Helga Peeters

2008-01-01

132

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

Microsoft Academic Search

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

Martin Schweigkofler; Reinhard Niessner

1999-01-01

133

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2010 CFR

...2009-04-01 true Poly(vinyl fluoride) resins. 175.270 Section 175.270 Food and Drugs...Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section may be safely...

2010-01-01

134

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270 Food and Drugs...Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section may be safely...

2012-04-01

135

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270 Food and Drugs...Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section may be safely...

2011-04-01

136

Personality impressions associated with four distinct humor styles.  

PubMed

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

Kuiper, Nicholas A; Leite, Catherine

2010-04-01

137

How good are our impressions? An audit of alginate impression quality in the production of removable prostheses.  

PubMed

Impressions are taken regularly in practice giving vital information to the dental laboratory, but are there quality assurance systems in place to make sure that they are up to a sufficient standard? As dental professionals we have to appreciate that dental technicians can only work with the information given to them. This makes the skill of taking a good impression vital in order for us as clinicians to provide prostheses of good quality. This paper outlines an audit of alginate impressions and their quality in the making of removable prostheses. Clinical Relevance: To record the quality of impression taking, and how one's own ability to critique an impression may differ from that of our colleagues. PMID:24930259

Horwitz, Richard

2014-05-01

138

The Irresistible Costs of Impressing Others Managing Impressions and Regulating Behavior  

NSDL National Science Digital Library

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.

Mcminn, Jamie G.

2007-01-01

139

Effects of Thermal Curing Conditions on Drug Release from Polyvinyl Acetate–Polyvinyl Pyrrolidone Matrices  

Microsoft Academic Search

This study aimed to investigate the effects of dry and humid heat curing on the physical and drug release properties of polyvinyl\\u000a acetate–polyvinyl pyrrolidone matrices. Both conditions resulted in increased tablet hardness; tablets stored under humid\\u000a conditions showed high plasticity and deformed during hardness testing. Release from the matrices was dependent on the filler's\\u000a type and level. Release profiles showed

Hatim S. AlKhatib; Saja Hamed; Mohammad K. Mohammad; Yasser Bustanji; Bashar AlKhalidi; Khaled M. Aiedeh; Samer Najjar

2010-01-01

140

Molecular toughening of epoxy resins through siloxane modification  

NASA Astrophysics Data System (ADS)

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.

Zhang, Man

141

Polyfunctional Biologically Active Polyvinyl Alcohol Film Materials  

Microsoft Academic Search

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

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

2001-01-01

142

Sisal cellulose whiskers reinforced polyvinyl acetate nanocomposites  

Microsoft Academic Search

Sisal nanowhiskers were used as novel reinforcement to obtain nanocomposites with polyvinyl acetate (PVAc) as matrix phase. They are seen as attractive materials due to the widespread availability and low cost of the sisal source material. Statistical analysis of the sisal whisker length and diameter resulted in average values of 250 nm and 4 nm, respectively, resulting in an average aspect ratio

Nancy Lis Garcia de Rodriguez; Wim Thielemans; Alain Dufresne

2006-01-01

143

Construction of Experimental Polyvinyl Chloride (PVC) Roofing.  

National Technical Information Service (NTIS)

Polyvinyl chloride (PVC) singly-ply roofing systems have been installed at three U.S. military facilities for long-term evaluation (10 years) in three environments. Commercial PVC systems previously had been shown to offer an alternative to conventional b...

M. J. Rosenfield

1984-01-01

144

Design of high-performance holographic gratings using siloxane-containing mesogenic compounds  

Microsoft Academic Search

Fine holographic gratings were fabricated using siloxane- and mesogen-containing compounds. A grating with 40 % diffraction efficiency was formed with 10 wt % non-liquid- crystalline 4-methoxyphenyl 4-(4-(pentamethyldisiloxanyl)butoxy)benzoate and trimethylol- propane triacrylate. 4-Methoxyphenyl 4-(4-(1,1,3,3,5,5,5-heptamethyltrisiloxan-1-yl)bu- toxy)-benzoate gave 50 % diffraction efficiency and angular selectivity of 5°. Siloxane-containing liquid-crystalline compounds were also effective in fabricating fine gratings. These compounds induced distinct phase separation

Yusuke Kawakami; Yeong Hee Cho

2006-01-01

145

Wettability of elastomeric impression materials and voids in gypsum casts.  

PubMed

Numerous factors are involved in making an accurate void-free dental artificial stone cast or die. The relationship of the wettability of an elastomeric impression material and its interaction with the gypsum slurry is an important factor. This study examined the relative "pourability" of several impression materials by counting the number of resultant voids in artificial stone casts containing 48 point angles. Those elastomers that exhibited the lowest contact angle with water produced artificial stone casts with the fewest voids. Surfactants applied to the impression material significantly reduced the number of voids in artificial stone casts, as did modified elastomers designated by the manufacturer as hydrophilic. PMID:1774689

Cullen, D R; Mikesell, J W; Sandrik, J L

1991-08-01

146

A Clinical and Laboratory Comparison of Alginate Impression Techniques.  

National Technical Information Service (NTIS)

A clinical and laboratory comparison of alginate impression techniques was undertaken. Rim-lock (trademark) trays were modified with a combination of modeling compound, wax, and alginate adhesive. Both the modified and unmodified trays were used to make a...

J. O. Hollinger, L. Lorton, W. A. Krantz

1981-01-01

147

Characterization of Indentation Impressions on Human Enamel for Hardness Measurement.  

National Technical Information Service (NTIS)

This paper presents results from investigating indentation impressions on human enamel under micro-hardness tests. The experiments of hardness testing were performed on a microhardness indentation machine under different loading conditions. Images of inde...

G. Zhang D. T. Le S. R. Tucker S. J. Ng

2006-01-01

148

Electronic evaluation for video commercials by impression index.  

PubMed

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

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

2013-12-01

149

Synthetic casting tape as a facial impression tray material.  

PubMed

A procedure is described that uses thermoplastic synthetic casting tape for fabrication of facial impression trays. Once used, these trays can be disinfected without degradation of the tray material, which allows for storage and later use. PMID:8537924

Saunders, T R; Hansen, N A

1995-08-01

150

Mechanics of Dental Retentive Pins and Impression Materials.  

National Technical Information Service (NTIS)

Initial studies are reported of problems of: (a) dental retentive pin installation and loading, and (b) deformation of dental impression materials; employing photoelastic and other techniques common to mechanical investigations of materials. Pin installat...

A. A. Caputo E. W. Collard J. P. Standlee S. C. Carniglia

1970-01-01

151

Studies on siloxane polymers for NIR-evanescent wave absorbance sensors  

Microsoft Academic Search

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

B. Zimmermann; J. Bürck; H.-J. Ache

1997-01-01

152

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

PubMed Central

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.

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

2014-01-01

153

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

Microsoft Academic Search

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

Solomon Bekele

1999-01-01

154

Polydimethyl Siloxane Toughened Epoxy Resins: Tensile Strength and Dynamic Mechanical Analysis  

Microsoft Academic Search

Mechanical properties of the Interpenetrating Polymer Networks (IPN's) based on epoxy resin and polydimethy siloxane (PDMS) were investigated. The main objective of the present work was to use PDMS as impact modifier for epoxy resin. New IPN's between epoxy resin and different weight percentage of PDMS were prepared in the presence of tetraethoxysilane (TEOS) as crosslinking for PDMS and triethylene

Whidad S. Hanoosh; Emad M. Abdelrazaq

155

Solvent effects on silica domain growth in silica\\/siloxane composite materials  

Microsoft Academic Search

The effect of solvent addition on the phase separation, mechanical Properties and thermal stability of silica\\/siloxane composite materials prepared by in situ reinforcement was examined. The addition of a solvent enhances the miscibility of the reinforcement precursor, a partial hydrolyzate of tetraethoxysilane (TEOS-PH), with the polydimethylsiloxane (PDMS) polymer. As a result, the phase separation at the micron level, termed the

T. A. Ulibarri; S. E. Bates; E. P. Black; D. W. Schaefer; W. G. Beaucage; M. K. Lee; P. A. Moore; G. T. Burns

1995-01-01

156

Auditory and visual spatial impression: Recent studies of three auditoria  

NASA Astrophysics Data System (ADS)

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

Nguyen, Andy; Cabrera, Densil

2004-10-01

157

A self-healing poly(dimethyl siloxane) elastomer  

NASA Astrophysics Data System (ADS)

In this work, self-healing functionality is imparted to a poly(dimethyl siloxane) (PDMS) elastomer with low modulus and high strain-to-failure behavior. This material utilizes a two-microcapsule system to provide a mechanism for autonomic repair of damage. One microcapsule type contains a functionalized high-molecular-weight resin and organometallic catalyst compounds. The second microcapsule type contains a functional copolymer (initiator) that facilitates the crosslinking of the resin via the action of the catalyst. The healing response is triggered when damage, in the form of a tear, puncture, or crack, propagates through the material and ruptures a resin and initiator capsule. Ruptured capsules release their contents onto the crack plane, initiating polymerization. The polymerized material bonds the two crack faces together regaining much of the original strength, of the matrix material. The mechanical behavior of the microcapsules is studied using a combination of individual microcapsule compression tests and in-situ microscopic analysis. Single-capsule compression tests are performed to extract the modulus of the capsule shell wall and to investigate the behavior of microcapsules under large deformations. The capsules are shown to survive matrix deformation in excess of 45%. Although the microcapsules are robust and endure large matrix deformations, an approaching tear does successfully rupture the capsules. A tear test protocol is adopted to assess the healing efficiency of this new material. Self-healing PDMS specimens with 5 wt% initiator and 5 wt% resin microcapsules recover 97% of the original tear strength. Complete recovery of tear strength is possible under certain conditions. Addition of microcapsules to the PDMS matrix increases the tear strength of the material by 25%. Embedded microcapsules also increase the elastic stiffness by as much as 57%. The self-healing performance of the elastomer is also investigated under torsional fatigue loading. The microcapsule-based self-healing PDMS is capable of recovering a significant portion of the original torsional stiffness and retards dynamic crack growth rate. Depending on the matrix material, a nearly complete recovery of the original torsional stiffness is possible.

Keller, Michael Wade

158

Biochemistry of microbial polyvinyl alcohol degradation  

Microsoft Academic Search

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

Fusako Kawai; Xiaoping Hu

2009-01-01

159

Destruction of polyvinyl chloride under extrusion  

NASA Astrophysics Data System (ADS)

An common industrial application of polyvinyl chloride (PVC) is the extrusive insulation of electric wires and cables. Experimental results are presented on the thermal and mechanical destruction of PVC under extrusion. Under extrusion conditions (at temperatures higher than 150 C), the evolution of hydrogen chloride determines practically the entire process of PVC destruction. The use of the present data to establish hygienic standards regarding safe concentrations of PVC destruction products in the work environment is discussed.

Dmitriev, M. T.; Serebriakova, R. V.; Serebriakov, V. N.; Zimin, P. N.; Nastenko, A. V.; Derevianchenko, L. G.; Antsifirova, N. P.; Visloukh, V. V.

1982-08-01

160

[Distortion of working models using different silicone impression techniques].  

PubMed

The influences of differing strains levels of impression materials in compression and impression techniques on the distortion of working models were examined. The working models, which differed in the size of cervical spillway (2mm and 9mm) and the impression techniques applied (the two-phase technique and the wash technique), were produced by using putty-type impression materials with three different strain levels (Reprosil, Express and Exaflex) following the metal master model of mandibular denture in an abutment form. Distortion of the working models was then measured by a three-dimensional measuring system. The results were as follows. 1) The models produced through the impression technique using hard impression materials with low strain levels displayed decreases both in the degree of inclination to the X axis of the abutment tooth variations distance between the left and right abutment teeth. This procedure was found to yield a model which was proximate to the master model. 2) The impression technique incorporating a small cervical spillway resulted in decreases in variations in the distance between the right and left abutment teeth and the diameter of the molar part of the abutment tooth, and the horizontal distortion of the alveolar ridge; the model thus produced was found to be proximate to the master model. 3) Application of the two-phase technique reduced variations in height of the abutment tooth, and the use of the wash technique led to decreased variations in the distance between the right and left abutment teeth and diameter of the molar cervix of the abutment tooth. 4) Differences in strain levels of putty-type impression materials, the size of cervical spillway and the impression technique used did not influence deviation of the model toward the Y axis (vertical direction). 5) The models with least distortion of the abutment tooth were obtained by the two-phase technique using hard impression materials with lower strain levels or by the wash technique using soft materials with higher strain levels. PMID:2489335

Yomaru, H; Ohtake, H; Yokozuka, S

1989-10-01

161

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

National Technical Information Service (NTIS)

Siloxanes have a wide variety of applications throughout the aerospace industry which take advantage of their exceptional insulating and adhesive properties and general resilience. They also offer a wide range of tailorable engineering properties with cha...

S. C. Chinn J. L. Herberg A. M. Sawvel R. S. Maxwell

2005-01-01

162

40 CFR 61.64 - Emission standard for polyvinyl chloride plants.  

Code of Federal Regulations, 2013 CFR

... Emission standard for polyvinyl chloride plants. 61.64 Section 61.64 Protection... Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of...

2013-07-01

163

40 CFR 61.65 - Emission standard for ethylene dichloride, vinyl chloride and polyvinyl chloride plants.  

Code of Federal Regulations, 2010 CFR

...dichloride, vinyl chloride and polyvinyl chloride plants. 61.65 Section...dichloride, vinyl chloride and polyvinyl chloride plants. An owner or operator...vinyl chloride, and/or polyvinyl chloride plant shall comply with...

2010-07-01

164

The Use of Impression Management Tactics in Structured Interviews: A Function of Question Type?  

Microsoft Academic Search

This study investigated impression management tactic use during structured interviews containing both experience-based and situational questions. Specifically, the authors examined whether applicants' use of impression management tactics depended on question type. Results from 119 structured interviews indicated that almost all of the applicants used some form of impression management. Significantly more assertive than defensive impression management tactics were used, and

Aleksander P. J. Ellis; Bradley J. West; Ann Marie Ryan; Richard P. DeShon

2002-01-01

165

The use of impression management tactics in structured interviews: A function of question type?  

Microsoft Academic Search

This study investigated impression management tactic use during structured interviews containing both experience-based and situational questions. Specifically, the authors examined whether applicants' use of impression management tactics depended on question type. Results from 119 structured interviews indicated that almost all of the applicants used some form of impression management. Significantly more assertive than defensive impression management tactics were used, and

Aleksander P. J. Ellis; Bradley J. West; Ann Marie Ryan; Richard P. DeShon

2002-01-01

166

Comparison of elastomeric impression materials used in fixed prosthodontics.  

PubMed

Five elastomeric impression materials were evaluated: two polysulfides (one lead-cure and one non-lead cure), two silicones (one condensation polymerization and one addition polymerization), and one polyether. These materials were subjected to simulated clinical conditions. Two techniques were evaluated. All materials were evaluated initially with use of a custom tray and manufacturers' adhesive. A second evaluation was performed without using the tray system. Both techniques were subjected to statistical comparison. Conclusions of the research were as follows: 1. All impression materials that were poured immediately and evaluated using a custom tray and adhesive consistently demonstrated superior results in comparison to those tested without the custom tray. 2. Polyether material consistently yielded superior results with or without a custom tray when compared to the other impression materials. The additional polymerization silicone ranked second, followed by the lead-cure polysulfide and the condensation polymerization silicone, respectively. PMID:7007629

Ciesco, J N; Malone, W F; Sandrik, J L; Mazur, B

1981-01-01

167

Forming impressions: effects of facial expression and gender stereotypes.  

PubMed

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

Hack, Tay

2014-04-01

168

Impression creep characterization of TiAl weldments  

SciTech Connect

The Impression Creep technique has been applied to XD{trademark} TiAl weldments to evaluate the local creep resistance of the fusion zone and the heat affected zone. The material used in this study was TiAl produced by Martin Marietta Research Laboratories, using their patented ingot processing which incorporates 1 to 10 {mu}m diameter particles of carbide, nitride or boride compounds. The impression creep technique uses a small indenter to locally evaluate the creep resistance of the heterogeneous microstructure developed during the welding process. The indenters used in this investigation were 1 mm in diameter. Results obtained from the impression creep tests are compared to results obtained from constant stress tensile creep tests on the base material. Creep resistance of the heat affected zone and the fusion zone are compared to and contrasted with the base material strength. 19 refs., 2 figs., 2 tabs.

Gibbs, W.S.; Aikin, R.M. Sr.; Martin, P.L.; Patterson, R.A.

1990-01-01

169

Study of miscibility and interaction in polyvinyl chloride-polyvinyl acetate blend using ultrasonic technique  

NASA Astrophysics Data System (ADS)

The propagation of ultrasonic waves and the measurement of their velocity in solutions form an important tool for the evaluation of various acoustical and thermo dynamical parameters which give an insight into the nature of miscibility and molecular interactions in polymer blend. In the present investigation, ultrasonic velocities, densities and viscosities have been measured in 0.1M solution of polyvinyl chloride in tetrahydrofuran using pulse echo overlap technique at 298K at different concentrations of polyvinyl acetate. Thermoacoustical parameters such as adiabatic compressibility, molar sound velocity, molar compressibility, expansion coefficient, acoustic impedance, van der Waals' constant and internal pressure have been computed from the experimental data. The variation of ultrasonic velocity and other thermo-acoustical parameters shows nonlinear increase or decrease with molar concentration which suggest immiscibility or semi compatibility among the component polymers. Two immiscible polymers are need to be compatibilized in order to be used in commercial applications. The nature of solvent-polymer-polymer interaction and the effect of concentration on the molecular interaction of polyvinyl chloride and polyvinyl acetate in tetrahydrofuran have been studied.

Tabhane, P. V.; Chimankar, O. P.; Shriwas, R. S.; Dudhe, C. M.; Tabhane, V. A.

2012-12-01

170

Microstructural Organization of Elastomeric Polyurethanes with Siloxane-Containing Soft Segments  

NASA Astrophysics Data System (ADS)

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.

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

2011-03-01

171

Effects of siloxane plasma coating on the frictional properties of polyester and polyamide fabrics  

Microsoft Academic Search

Hydrophobic siloxane plasma coatings (pp-HMDSO) were deposited on flexible polymeric substrates in order to investigate their performance within different tribo systems. The frictional properties of plasma-coated foils and fabrics were thus examined using the Textile Friction Analyzer. The friction measurements were realized under dry, wet and saturated conditions to simulate sweating during running and using two different tribo-partners (i.e. steel

E. Bertaux; E. Le Marec; D. Crespy; R. Rossi; D. Hegemann

2009-01-01

172

Infrared spectroscopic analysis of siloxane network modification of mesoporous silica film by silylation and cesium doping  

Microsoft Academic Search

Effects of pore surface silylation and cesium doping on the siloxane bonding structure of mesoporous silica (MPS) film were analyzed using infrared spectroscopy. MPS film was derived by sol–gel method and self-assembling technology of non-ionic surfactant template. Cesium (Cs) catalyst was doped to the precursor solution with the amounts of 0, 5, and 15 wt-ppm. Vapor phase silylation was performed

Yasuhsia Kayaba; Kazuo Kohmura; Hirofumi Tanaka; Yutaka Seino; Toshiyuki Ohdaira; Shinichi Chikaki; Takamaro Kikkawa

2010-01-01

173

Optimization of the processing parameters in melt blending of thermoplastic polyurethane and poly dimethyl siloxane rubber  

Microsoft Academic Search

This article emphasizes the optimization of processing parameters required for the blending of polyether-based thermoplastic polyurethane (TPU) and poly dimethyl siloxane (PDMS) rubber. Taguchi methodology was adapted as a statistical tool in the design of experiment to optimize processing conditions on the basis of tensile strength and impact strength for 50:50 blend of TPU and PDMS. L9 (33) orthogonal array

Jineesh Ayippadath Gopi; Golok Bihari Nando

2012-01-01

174

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

Microsoft Academic Search

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

Lei Ren; Kanji Tsuru; Satoshi Hayakawa; Akiyoshi Osaka

2002-01-01

175

Preparation of Siloxane-modified Tetraglycidyl Epoxy-Clay Nanocomposites - Its Thermal and Morphological Properties  

Microsoft Academic Search

The organic—inorganic hybrid involving hydroxyl-terminated polydimethylsiloxane (HTPDMS)-modified epoxy, filled with organo-modified flurohectorite clay of various percentages (1—5 wt%) were prepared via in situ polymerization using ?-amino propyltriethoxysilane as cross-linking agent in the presence of dibutyltindilaurate catalyst. The reactions involved during the curing process between epoxy and siloxane were confirmed by FT-IR. The results of differential scanning calorimetry and dynamic mechanical

A. Selvaganapathi; M. Alagar; P. Gnanasundaram; A. Gedanken

2010-01-01

176

Physicochemical Modification of Siloxane Compounds for Electrical Engineering in the Course of Mixing  

Microsoft Academic Search

The effect of silica fillers, used separately or in combination, on the rheological properties of siloxane compounds based on low- and high-molecular-weight rubbers was studied. A model was suggested for formation of the structure of filled compounds during mixing under conditions of shear stresses, and a procedure was proposed for preparing compounds for shells of high-voltage insulators produced by pressure

D. N. Lazarev; V. P. Britov; V. V. Bogdanov

2001-01-01

177

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

Microsoft Academic Search

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

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

1999-01-01

178

Synthesis and UV shielding properties of zinc oxide ultrafine particles modified with silica and trimethyl siloxane  

Microsoft Academic Search

This paper introduces a kind of ZnO ultrafine particles modified with silica and trimethyl siloxane (TMS). Thus zinc carbonate hydroxide (ZCH) as the precursor of ZnO was synthesized using chemical precipitation method, and the precursor was modified in situ with silica and TMS. The modified ZnO ultrafine particles were obtained after calcinating the modified precursors. The surface properties of the

Zhi Cao; Zhijun Zhang; Fenxia Wang; Guangzhong Wang

2009-01-01

179

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

Microsoft Academic Search

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

Shingo Tokuda; Akiko Obata; Toshihiro Kasuga

2009-01-01

180

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

PubMed Central

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

Albright, Abigail; Gawley, Robert E.

2011-01-01

181

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

PubMed

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

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

2010-11-01

182

Seeing Writing Instruction Differently: Lessons with Lasting Impressions  

ERIC Educational Resources Information Center

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

Bintz, William P.; Dillard, Jill

2004-01-01

183

Emotional Regulation at Walt Disney World: An Impression Management View  

Microsoft Academic Search

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

Anne Reyers; Jonathan Matusitz

2012-01-01

184

Cross-Cultural Impression Management: A Cultural Knowledge Audit Model  

ERIC Educational Resources Information Center

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…

Spong, Abigail; Kamau, Caroline

2012-01-01

185

Corporate governance and impression management in annual press releases  

Microsoft Academic Search

We study the association between corporate governance and impression management in annual results press releases (ARPRs). Press releases constitute a timely vehicle to communicate firm performance to third parties. However, oftentimes, managers provide self-serving disclosures that attempt to distort readers¿ perceptions of corporate achievements. Corporate governance mechanisms actively monitor managerial disclosures, improving firm transparency. Thus, we predict that strong governance

Beatriz García Osma; Encarna Guillamón Saorín

2009-01-01

186

Impression Formation in Children: Influence of Gender and Expectancy.  

ERIC Educational Resources Information Center

A total of 114 boys and girls were given an expectancy that a stimulus child was either shy or outgoing and then rated the child on several personality dimensions. Results revealed that, when children were presented with both expectancy-congruent and expectancy-incongruent information, impression formation was largely attribute based, and the…

McAninch, Cecile B.; And Others

1993-01-01

187

Microbiological evaluation of ultrasonic nebulization for disinfecting dental impressions.  

PubMed

Disinfecting dental impressions is necessary to decrease the risk of cross-contamination in dental offices. Ultrasonic nebulization has been mentioned as a microbicidal technique that can be used to disinfect contaminated dental impressions. This study compared the microbicidal effect of 2% glutaraldehyde and 0.2% peracetic acid for the disinfection of dental impressions made with vinyl polysiloxane, using 2 disinfection methods: immersion and ultrasonic nebulization. Bactericial efficacy was examined using Staphylococcus aureus and Bacillus atrophaeus as indicators. Thirty impressions were obtained and distributed randomly in 5 groups (n = 6). Group 1 was immersed in 2% glutaraldehyde immersion for 10 minutes, Group 2 was immersed in 0.2% peracetic acid for 10 minutes, Group 3 underwent ultrasonic nebulization for 10 minutes in 2% glutaraldehyde solution, Group 4 underwent ultrasonic nebulization for 10 minutes in 0.2% peracetic acid solution, and Group 5 was a control group that received no disinfectant. Both solutions experienced a 100% reduction in microorganisms following ultrasonic nebulization, as did peracetic acid following immersion; however, immersion in glutaraldehyde demonstrated lower values of reduction in B atrophaeus group, with a statistically significant difference compared with the other experimental groups. PMID:23823336

Mendonca, Marcio Jose; Rafael, Renata Santos; Camilotti, Veridiana; Menolli, Rafael Andrade; Sicoli, Eliseu Augusto; Teixeira, Nancielli; Sinhoreti, Mario Alexandre Coelho

2013-07-01

188

Making an Impression: YA Authors and Their Influential Teachers  

ERIC Educational Resources Information Center

This article recounts significant moments from online interviews these authors conducted with Young Adult (YA) authors concerning the teachers who left a lasting impression on them and assisted them in finding their voice and unique writing abilities. S. E. Hinton, Walter Dean Myers, Erin Gruwell, Chris Crutcher, and other popular YA authors…

Eisenbach, Brooke; Kaywell, Joan F.

2013-01-01

189

Impression management and Self-Deception in traffic behaviour inventories  

Microsoft Academic Search

Traffic behaviour questionnaires as self-reports of behaviour are easily biased by Socially Desirable Responding (SDR), especially in investigating ‘normal’ behaviour rather than maximum performance. Despite this fact no instruments are available for measuring traffic related SDR. The present study introduces a new inventory, the Driver Social Desirability Scale (DSDS), for measuring driver impression management (DIM) and Driver Self-Deception (DSD). The

Timo Lajunen; Angela Corry; Heikki Summala; Laurence Hartley

1997-01-01

190

Impression Management Use and Effectiveness Across Assessment Methods  

Microsoft Academic Search

Considerable research has focused on candidate impression management (IM) use in unstructured interviews. However, little research has explored candidate IM use in other, frequently used assessment methods. This study examines the extent to which candidates, under consideration for a promotion, use verbal IM tactics in two types of structured individual assessment methods: a situational interview and a role-play. Based on

S. David Kriska

2003-01-01

191

Impressions of a Middle Grades STEM Integration Program  

ERIC Educational Resources Information Center

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…

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

2011-01-01

192

The Neurological-Impress Method of Teaching Reading.  

ERIC Educational Resources Information Center

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

Partridge, Susan

193

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 ...

194

Irradiation of polyvinyl alcohol and polyvinyl pyrrolidone blended hydrogel for wound dressing  

NASA Astrophysics Data System (ADS)

Polyvinyl alcohol and polyvinyl pyrrolidone (PVA-PVP) blended hydrogel for wound dressing has been prepared by using gamma rays irradiation technique. The gel fraction, mechanical properties, the water content and water absorption performance of the hydrogels were measured. It was found that the gel fraction increases with increasing irradiation dose but never reaches 100% of gel. The PVA/PVP blended hydrogel has a water content in the range between 60% and 80% and water absorption between 40% and 250%. The water vapor transmission rate value (WVTR) of the PVA/PVP blended hydrogel varies between 50 and 200 g/m 2/h. The hydrogel could be considered as good barrier against microbes. According to in vitro assessment it was found that the PVA/PVP blended hydrogel was very useful material that can meet the efficacy requirement and its healing rate was comparable with sterilized gauze and sofratulle.

Razzak, Mirzan T.; Darwis, Darmawan; Zainuddin; Sukirno

2001-07-01

195

[Survey of plasticizers in polyvinyl chloride toys].  

PubMed

Plasticizers in 101 samples of polyvinyl chloride (PVC) toys on the Japanese market were surveyed. No phthalates were detected in designated toys, though bis(2-ethylhexyl)phthalate, diisononyl phthalate, diisobutyl phthalate, dibutyl phthalate, diisodecyl phthalate and benzyl butyl phthalate were detected in more than half of other toys. 2,2,4-Tributyl-1,3-pentanediol diisobutylate, o-acetyl tributyl citrate, adipates and diacetyl lauroyl glycerol, which are alternative plasticizers to phthalates, were detected. The results of structural analysis confirmed the presence of di(2-ethylhexyl)terephthalate, tributyl citrate, diisononyl 1,2-cyclohexanedicarboxylate and neopentyl glycol esters; these have not previonsly been reported in Japan. There appears to be a shift in plasticizers used for designated toys from phthalates to new plasticizers, and the number of different plasticizers is increasing. PMID:22450665

Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Hirahara, Yoshichika; Kawamura, Yoko

2012-01-01

196

Orientation of cellulose nanowhiskers in polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

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

Kvien, I.; Oksman, K.

2007-06-01

197

Cryotropic gelation of poly(vinyl alcohol) solutions  

NASA Astrophysics Data System (ADS)

The mechanisms of the cryotropic gelation of poly(vinyl alcohol) solutions as well as the influence of the characteristics of the polymer and the conditions of the cryogenic treatment on the structure and physicochemical properties of the cryogels obtained are examined. Data on the characteristics of the freezing of concentrated poly(vinyl alcohol) solutions are presented. The influence of soluble additives, possessing different lyotropic properties, on the course of gelation in frozen systems is discussed. The possibility of the cryocracking of poly(vinyl alcohol) chains is considered. The bibliography includes 349 references.

Lozinsky, Vladimir I.

1998-07-01

198

Studies on surface wettability of poly(dimethyl) siloxane (PDMS) and glass under oxygen-plasma treatment and correlation with bond strength  

Microsoft Academic Search

An issue in microfabrication of the fluidic channels in glass\\/poly (dimethyl siloxane) (PDMS) is the absence of a well-defined study of the bonding strength between the surfaces making up these channels. Although most of the research papers mention the use of oxygen plasma for developing chemical (siloxane) bonds between the participating surfaces, yet they only define a certain set of

Shantanu Bhattacharya; Arindom Datta; Jordan M. Berg; Shubhra Gangopadhyay

2005-01-01

199

Analysis of a mixture of linear and cyclic siloxanes by cryo-gas chromatography-Fourier transform infrared spectroscopy and gas chromatography-mass spectrometry  

Microsoft Academic Search

A mixture of linear and cyclic methylsiloxanes was analysed to characterize the different types of siloxane structures using gas chromatography (GC), mass spectrometry (MS) and Fourier transform infrared (FT-IR) spectroscopy. Siloxane structures are formed by hydrolysis of dimethyldichlorosilane under controlled conditions in technical applications. In the presence of methyltrichlorosilane or even trimethylchlorosilane, linear polydimethylsiloxanes and mono-, bi- or polycyclic methylsiloxanes

S. Wachholz; F. Keidel; U. Just; H. Geissler; K. Käppler

1995-01-01

200

Impression Material Mass Retained in the Mucobuccal Fold  

PubMed Central

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.

Karam Genno, N.; Assaf, A.

2014-01-01

201

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

PubMed

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

Johnson, Anne

2014-05-01

202

Predicting Trait Impressions of Faces Using Classifier Ensembles  

Microsoft Academic Search

In the experiments presented in this chapter, single classifier systems and ensembles are trained to detect the social meanings\\u000a people perceive in facial morphology. Exploring machine models of people’s impressions of faces has value in the fields of\\u000a social psychology and human-computer interaction. Our first concern in designing this study was developing a sound ground\\u000a truth for this problem domain.

Sheryl Brahnam; Loris Nanni

203

Automatic Generation of Computer Animation Conveying Impressions of News Articles  

Microsoft Academic Search

This paper proposes a passive viewing interface, called News Reader with Emotional Expressions (wEE), which automatically\\u000a generates TV program-like animations with synthesized emotional speech and background music from news articles in a user-specified\\u000a Web news site. A distinctive point of our interface is that it explicitly conveys the impressions of news articles to users\\u000a by determining appropriate background music and

Tadahiko Kumamoto; Akiyo Nadamoto; Katsumi Tanaka

2008-01-01

204

Cost of Impressed Current Cathodic Protection for Coastal Oregon Bridges  

Microsoft Academic Search

The State of Oregon is using arc-sprayed zinc coatings for anodes in impressed current cathodic protection (ICCP) systems on reinforced concrete coastal bridges. The two lowest bids for four ICCP projects were averaged and converted to 1997 dollars. The total average cost for the ICCP projects was $51.63\\/ft2 ($555.51\\/m2) of protected concrete. The cathodic protection part of the ICCP projects

Gordon R. Holcomb; Curtis B. Cryer

1998-01-01

205

Duplication of interim speech aid for definitive impression tray fabrication.  

PubMed

A wax tray is stable and easily relieved if overextended. Unusual tray undercuts or angles needed for the partial resection patient need not be eliminated before the impression procedure. Relief of these undercuts is necessary with acrylic resin trays to ensure separation from the final stone cast. Because the wax tray is separated easily from the prosthesis during the boil-out, it is not necessary to "burn" or grind acrylic resin from the framework. The tray shape is duplicated from the existing interim prosthesis on the nasopharyngeal and oropharyngeal side. An arbitrarily shaped acrylic resin tray may be grossly overextended and require time-consuming clinical adjustments. An underextended tray on the nasopharyngeal side will not carry or support the impression material around or through the residual soft palate remnant. A tray that closely approximates the final prosthesis will allow use of a tissue conditioner final impression without need for border molding (Fig. 2). Duplicating the oropharyngeal side of the interim speech aid duplicates the previously established plane that is compatible with the tongue. The author has used this technique successfully for eight total and five partial soft palate resections. A cleft palate speech aid prosthesis has also been made with this technique. PMID:1432786

Jacob, R F

1992-09-01

206

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

Code of Federal Regulations, 2010 CFR

... false Optical Impression Systems for CAD/CAM. 872.3661 Section 872.3661...3661 Optical Impression Systems for CAD/CAM. (a) Identification. An...computer assisted design and manufacturing (CAD/CAM) is a device used to...

2010-04-01

207

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

Code of Federal Regulations, 2010 CFR

... false Optical Impression Systems for CAD/CAM. 872.3661 Section 872.3661...3661 Optical Impression Systems for CAD/CAM. (a) Identification. An...computer assisted design and manufacturing (CAD/CAM) is a device used to...

2009-04-01

208

Characterization and impression creep testing of silicon aluminum oxynitride ceramics  

NASA Astrophysics Data System (ADS)

Three Yb-containing SiAlON materials were studied for potential use as hot section components in advanced microturbine engines. Two of the materials consisted of equiaxed alpha-SiAlON grains, elongated beta-SiAlON grains, and an amorphous intergranular phase containing a relatively large amount of Yb. The third material consisted of alpha- and beta-SiAlON grains with equiaxed morphologies and virtually no intergranular phase. An instrument was designed and constructed for impression creep testing of the YbSiAlON materials. Uniaxial compression creep experiments were also performed for comparison. In compression creep, the SiAlON materials exhibited activation energies that were similar to those of other SiAlONs reports in the literature, and stress exponents that were approximately 1. In impression creep, the SiAlONs tested exhibited activation energies similar to those reported in the literature for SiAlONs tested in uniaxial compression and tension. However, the SiAlON composition with equiaxed beta-SiAlON grains showed an exaggerated activation energy due to a change in creep mechanism above 1340°C. The measured stress exponents in impression creep were approximately 2. The stress state present below the punch in impression creep caused dilation to occur in the grain structure. The dilation results in an increase in the volume of the multi-grain junctions, and an increased dependence of strain rate on stress. The enlarged multi-grain junctions can become filled with the intergranular glassy phase. These large pockets of the glassy phase can enable an additional creep mechanism whereby the equiaxed grains slide past each other viscously. All of the SiAlONs developed an additional volume of the intergranular glassy phase during creep testing. A microstructure containing elongated beta-SiAlON grains is most effective in enhancing creep performance of the Yb-SiAlON materials tested. The impression creep data for the Yb-SiAlON materials can be related to the compression creep data by using a stress correction factor of 1.6 and an effective gauge length of 1.2 times the punch diameter when the creep testing conditions are the same.

Fox, Kevin M.

209

Formalized Poly(Vinyl Alcohol) Membranes for Reverse Osmosis.  

National Technical Information Service (NTIS)

The permeation properties of formalized poly(vinyl alcohol) membranes are described. The interest of this work is centered on the properties relevant to desalination by reverse osmosis. These membranes, when properly prepared, showed reasonably high water...

A. V. Tobolsky C. T. Chen M. C. Chen Y. J. Chang

1972-01-01

210

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2013 CFR

...HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: POLYMERS Substances for Use as Basic Components of Single and Repeated...alcohol film is produced from polyvinyl alcohol having a minimum viscosity of 4 centipoises when a 4-percent aqueous solution is...

2013-04-01

211

Wastewater Treatment Facilities for a Polyvinyl Chloride Production Plant.  

National Technical Information Service (NTIS)

The report discusses the investigations of various types of wastewater treatment systems to adequately treat wastes from a polyvinyl chloride plant. Both primary and secondary treatment methods were investigated. Waste equalization; solids removal by chem...

1971-01-01

212

Synthesis of boron carbide powder from polyvinyl borate precursor  

Microsoft Academic Search

Polyvinyl borate (PVBO) was prepared by the condensation of poly(vinyl alcohol) (PVA) and boric acid, and used as a precursor for boron carbide. Boron carbide powder was synthesized by the pyrolysis of the PVBO precursor in air at 600 °C for 2 h, followed by heat treatment in Ar flow at 1300 °C for 5 h, which is a relatively low temperature compared with

Ikuo Yanase; Riichi Ogawara; Hidehiko Kobayashi

2009-01-01

213

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

ERIC Educational Resources Information Center

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…

Van Der Heide, Brandon Lee

2009-01-01

214

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

ERIC Educational Resources Information Center

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

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

2011-01-01

215

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

Microsoft Academic Search

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

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

2008-01-01

216

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

NASA Astrophysics Data System (ADS)

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.

Sonoc, Alexandru Catalin

217

The influence of poly(ethylene oxide) grafting via siloxane tethers on protein adsorption  

Microsoft Academic Search

Amphiphilic PEO–silanes (a–c) having siloxane tethers of varying lengths with the general formula ?-(EtO)3Si–(CH2)2–oligodimethylsiloxanen-block-poly(ethylene oxide)8–OCH3 [n=0 (a), n=4 (b), and n=13 (c)] were grafted onto silicon wafers and resistance to adsorption of plasma proteins was measured. Distancing the PEO segment from the hydrolyzable triethoxysilane [(EtO)3Si] grafting group by a oligodimethylsiloxane tether represents a new method of grafting PEO chains to

Ranjini Murthy; Courtney E. Shell; Melissa A. Grunlan

2009-01-01

218

Full arch scans: conventional versus digital impressions--an in-vitro study.  

PubMed

The digital intraoral impression has become a central part of the CAD/CAM technique. The objective of the present study was to compare the accuracy (trueness and precision) of digital impressions of the full arch with that of conventional impressions on the in-vitro model. For this purpose, a master model was acquired with a new reference scanning process, the measuring trueness of which was +/- 4.1 microm and the precision +/- 2.5 microm. On the one hand, conventional impressions and then plaster models (n = 5) were produced from this master model, and on the other hand, digital impressions were made with the Cerec AC Bluecam and the Lava COS system (each n = 5). The plaster models were also scanned with the reference scanner. The available data records were superimposed and the differences determined. The deviation from the master model defines the trueness of the impression method. The deviations of the models among one another demonstrate the precision of the method. The trueness of the impressions was 55 +/- 21.8 microm in the conventional impression group, for digital impressions with Cerec Bluecam it was 49 +/- 14.2 microm and for digital impressions with Lava COS 40.3 +/- 14.1 microm. The precision was 61.3 +/- 17.9 microm for conventional impression with Impregum, 30.9 +/- 7.1 microm for digital impression with the Cerec Bluecam and 60.1 +/- 31.3 microm for digital impression with Lava COS. These in-vitro results show that accuracy of the digital impression is similar to that of the conventional impression. These results will have to be confirmed in further clinical studies. PMID:21657122

Ender, A; Mehl, A

2011-01-01

219

[The dis-positive: metapsychological observations of the reality impression].  

PubMed

In the author's view, Plato's myth of the cave is an exact description of the movie theatre. In both there is a constraint to immobility, repetition and a return to a former state--a primary-process throwback to the immobility of the newborn infant and the sleeper. The captive in the cave, the cinema-goer and the sleeper are all-albeit in different ways--victims of an illusion of reality, an impression that deviates from reality, and are hence subjects of the unconscious. It is this more-than-the-real, this desire for desire, that in Baudry's view informs the history of cinema. PMID:7809393

Baudry, J L

1994-11-01

220

Polyvinyl acetate-based film coatings.  

PubMed

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

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

2013-12-01

221

Preparation and properties of polyvinyl alcohol microspheres  

SciTech Connect

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.

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

1986-06-01

222

Heat resistance poly(vinyl alcohol) hydrogel  

NASA Astrophysics Data System (ADS)

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

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

1995-08-01

223

Piezoresistive Properties of Polyvinyl Chloride Composites  

NASA Astrophysics Data System (ADS)

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

Toprakci, Hatice Aylin Karahan

224

Siloxane-poly(lactic acid)-vaterite composites with 3D cotton-like structure.  

PubMed

Trace amounts of ionic calcium and silicon species have been reported to stimulate the proliferation, differentiation, and mineralization of bone-forming cells. Composite materials comprising siloxane-doped calcium carbonate (vaterite) particles and poly(L-lactic acid) have been developed [siloxane-poly(lactic acid)-vaterite hybrid-composite, SiPVH] so far; they were designed such that calcium and silicate ions are gradually released from SiPVH and they show the chronic effects of ions on cellular activities. In the present work, SiPVH with a 3D cotton-like structure was prepared by electrospinning to obtain the major advantages of excellent bioactivity and ease of handling for bone filling surgery. The diameter of the fibrous skeletons that form structure of the cotton-like SiPVH was controlled to ~10 ?m to achieve cellular migration into the spaces between fibers. The resulting cotton-like SiPVH showed good flexibility. The fiber surface was coated rapidly with numerous particles of several hundred nanometers in size by alternate soaking in CaCl(2) and Na(2)HPO(4). The treated cotton-like material, which released calcium and silicate ions gradually, showed good cellular migration behavior into the 3D structure in cell culture tests using murine osteoblast-like MC3T3-E1 cells. PMID:22415363

Kasuga, Toshihiro; Obata, Akiko; Maeda, Hirotaka; Ota, Yoshio; Yao, Xianfeng; Oribe, Kazuya

2012-10-01

225

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

PubMed

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. PMID:23145738

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

2012-11-01

226

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

NASA Astrophysics Data System (ADS)

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.

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

2012-11-01

227

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

SciTech Connect

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

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

1995-07-01

228

Triblock siloxane copolymer surfactant: template for spherical mesoporous silica with a hexagonal pore ordering.  

PubMed

Ordered mesoporous silica materials with a spherical morphology have been prepared for the first time through the cooperative templating mechanism (CTM) by using a silicone triblock copolymer as template. The behavior of the pure siloxane copolymer amphiphile in water was first investigated. A direct micellar phase (L(1)) and a hexagonal (H(1)) liquid crystal were found. The determination of the structural parameters by SAXS measurements leads us to conclude that in the hexagonal liquid crystal phase a part of the ethylene oxide group is not hydrated as observed for the micelles. Mesoporous materials were then synthesized from the cooperative templating mechanism. The recovered materials were characterized by SAXS measurements, nitrogen adsorption-desorption analysis, and transmission and scanning electron microscopy. The results clearly evidence that one can control the morphology and the nanostructuring of the resulting material by modifying the synthesis parameters. Actually, highly ordered mesoporous materials with a spherical morphology have been obtained with a siloxane copolymer/tetramethoxysilane molar ratio of 0.10 after hydrothermal treatment at 100 °C. Our study also supports the fact that the interactions between micelles and the hydrolyzed precursor are one of the key parameters governing the formation of ordered mesostructures through the cooperative templating mechanism. Indeed, we have demonstrated that when the interactions between micelles are important, only wormhole-like structures are recovered. PMID:23305163

Stébé, M J; Emo, M; Forny-Le Follotec, A; Metlas-Komunjer, L; Pezron, I; Blin, J L

2013-02-01

229

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

PubMed

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. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 1859-1867, 2014. PMID:23776167

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

2014-06-01

230

Permeation of gases through composite membranes prepared by radio-frequency and microwave plasma polymerization of siloxanes  

Microsoft Academic Search

In this work, the permeation of gases and condensible vapors through composite membranes was studied. Helium, hydrogen, argon, oxygen, nitrogen, methane, carbon dioxide, ethylene, acetylene, sulfur dioxide, propane, n-butane and sulfur hexafluoride were used as permeant gases. Composite membranes were prepared by the deposition of either radio-frequency or microwave plasma polymerized siloxanes onto polymer substrates of porous Celgard. The starting

Akhil Lal

1999-01-01

231

Clinical Intuition in Family Medicine: More Than First Impressions  

PubMed Central

PURPOSE The clinical literature advises physicians not to trust their intuition. Studies of clinical intuition, however, equate it to early impressions, the first thing that comes to the physician’s mind. This study aimed to investigate the validity of this perspective by examining real cases of intuition in family medicine. METHODS Eighteen family physicians were interviewed about patient cases in which they believed that they had experienced an intuition. Cases were included if (1) participants were unaware of the basis of their judgment, or (2) participants talked about the basis of their judgment but believed that it was irrational or unsubstantiated. During the interview, case descriptions were systematically probed following the Critical Decision Method. Transcripts were coded for judgments, informational cues, expectancies, goals, and actions and were reordered into chronological accounts of the decision process. The 2 authors independently categorized cases into 3 emerging decision process types. RESULTS Participants reported 31 cases, 24 of which met inclusion criteria. Three types of decision process emerged: gut feelings, recognitions, and insights (? = 0.78). In all cases, participants thought that their intuitive judgment was in conflict with a more rational explanation or what other colleagues would do. CONCLUSIONS Automatic, nonanalytical processes in clinical judgment extend beyond first impressions. Rather than admonishing clinicians not to trust their intuition, it should be acknowledged that little is currently known about the different types of intuitive processes and what determines their success or failure. Research on the conditions for accurate clinical intuitions is needed.

Woolley, Amanda; Kostopoulou, Olga

2013-01-01

232

pH-Dependent rectification in redox polymers: Characterization of electrode-confined siloxane polymers containing naphthoquinone and benzylviologen subunits  

SciTech Connect

This paper describes the electrochemical characterization of electrode-confined siloxane polymers that contain both naphthoquinone (NQ) and benzylviologen (BV{sup 2}{sup +}) subunits. These `homopolymers,` abbreviated (NQ-BV{sup 3+}){sub n} and (NQ-BV-BV{sup 5+}){sub n}, are derived from monomers, 2-chloro-3-[[2-(dimethyl[[[N`-[[4-(trimethoxysilyl)phenyl]methyl]-4, 4`-bipyridiniumyl]methyl]phenyl]methyl]ammonium)-ethyl]amino]-1,4-naphthoquinone, 1a, and 2-chloro-3-[[2-(dimethyl[[[[[[[[N`-[N`-[[4-(trimethoxysilyl)phenyl]methy]-4,4`-bipyridiniumyl]methyl]-phenyl]methyl]-4, 4`-bipyridiniumyl]methyl]phenyl]methyl]ammonium)ethyl]amino]-1,4-naphthoquinone, 2a, respectively. Particular to these types of surface-confined homopolymers is the ability to `trap` charge at low pH in the form of reduced quinone. The flexibility of these monolayers apparently allows direct contact of the NQ subunit with the electrode surface. Less flexible and more robust surface-confined polymers, abbreviated (NQ-BV{sup 3+}/siloxane){sub n} and (NQH{sub 2}-BV-BV{sup 5+}siloxane){sub n}, can be prepared by copolymerization of 1a or 2a with 1,2-bis(trimethoxysilyl)ethane. Charge trapped in (NQH{sub 2}-BV{sup 3+}/siloxane){sub n} or (NQH{sub 2}-BV-BV{sup 5+}/siloxane){sub n} can be released and delivered to the surface of the electrode via chemical mediation or by an increase in solution pH. 26 refs., 13 figs.

Palmore, G.T.R.; Smith, D.K.; Wrighton, M.S. [Massachusetts Institute of Technology, Cambridge, MA (United States)] [Massachusetts Institute of Technology, Cambridge, MA (United States)

1997-04-03

233

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

234

40 CFR 61.64 - Emission standard for polyvinyl chloride plants.  

Code of Federal Regulations, 2010 CFR

...false Emission standard for polyvinyl chloride plants. 61.64 Section 61.64 ...National Emission Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a...

2010-07-01

235

40 CFR 61.64 - Emission standard for polyvinyl chloride plants.  

Code of Federal Regulations, 2010 CFR

...false Emission standard for polyvinyl chloride plants. 61.64 Section 61.64 ...National Emission Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a...

2009-07-01

236

Reactions between vinyl compounds and multifunctional compounds communication 2. Reactions of vinyl ethers with polyvinyl alcohol  

Microsoft Academic Search

Summary 1.A study has been made of the reactions between polyvinyl alcohol and butyl vinyl and phenyl vinyl ethers, the proportions of components being varied.2.It has been shown that reaction between polyvinyl alcohol and butyl vinyl or phenyl vinyl ether leads to the formation of polyacetals of polyvinyl alcohol.3.It is possible that the formation of the polyacetals of polyvinyl alcohol

M. F. Shostakovsky; V. V. Zhebrovsky; M. A. Medelyanovskaya

1954-01-01

237

Effects of Exposure to Advertisements on Audience Impressions  

NASA Astrophysics Data System (ADS)

This study investigated effects of listening and/or watching commercial-messages (CMs) on audience impressions. We carried out experiments of TV advertisements presentation in conditions of audio only, video only, and audio-video. As results, we confirmed the following two effects: image-multiple effect, that is, the audience brings to mind various images that are not directly expressed in the content, and marking-up effect, that is, the audience concentrates on some images that are directly expressed in the content. The image-multiple effect, in particular, strongly appeared under the audio only condition. Next, we investigated changes in the following seven subjective responses; usage image, experience, familiarity, exclusiveness, feeling at home, affection, and willingness to buy, after exposure to advertisements under conditions of audio only and audio-video. As a result, noting that the image-multiple effect became stronger as the evaluation scores of the responses increased.

Hasegawa, Hiroshi; Sato, Mie; Kasuga, Masao; Nagao, Yoshihide; Shono, Toru; Norose, Yuka; Oku, Ritsuya; Nogami, Akira; Miyazawa, Yoshitaka

238

The complex interplay between semantics and grammar in impression formation.  

PubMed

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

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

2014-09-01

239

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

PubMed

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

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

2012-01-01

240

Preparation and characterization of polyvinyl alcohol---chitosan biocompatible magnetic microparticles  

Microsoft Academic Search

This work addresses the obtaining of biocompatible magnetic polyvinyl alcohol---chitosan microspheres, specifically tailored\\/functionalised to bind directly blood toxins using an emulsion crosslinking preparation method. The following synthesis parameters were studied: water to oil phase ratio, polyvinyl alcohol molecular weight, chitosan to polyvinyl alcohol weight ratio, surfactant composition and concentration of the crosslinking agent. These parameters were optimized for producing a

Laura Elena Udrea; Doina Hritcu; Marcel Ionel Popa; Ovidiu Rotariu

2011-01-01

241

Preparation and characterization of polyvinyl alcohol—chitosan biocompatible magnetic microparticles  

Microsoft Academic Search

This work addresses the obtaining of biocompatible magnetic polyvinyl alcohol—chitosan microspheres, specifically tailored\\/functionalised to bind directly blood toxins using an emulsion crosslinking preparation method. The following synthesis parameters were studied: water to oil phase ratio, polyvinyl alcohol molecular weight, chitosan to polyvinyl alcohol weight ratio, surfactant composition and concentration of the crosslinking agent. These parameters were optimized for producing a

Laura Elena Udrea; Doina Hritcu; Marcel Ionel Popa; Ovidiu Rotariu

2011-01-01

242

Evaluation of an Environmentally Friendly Plasticizer For Polyvinyl Butyral For Use in Tape Casting  

Microsoft Academic Search

An environmentally friendly plasticizer for polyvinyl butyral has been evaluated and compared with the industry standard - butyl benzyl phthalate. Properties such as the effect on the glass transition temperature of polyvinyl butyral and its compatibility with several grades of polyvinyl butyral are discussed. A direct comparison of this plasticizer is made with the industry standard in side-by-side tape casting

Richard E. Mistler; Ernest Bianchi; Bruce Wade; Jeffrey Hurlbut

243

The epoxy-siloxane/Al composite coatings with low infrared emissivity for high temperature applications  

NASA Astrophysics Data System (ADS)

Low infrared emissivity coatings with good thermal resistance were prepared by using epoxy-siloxane and aluminum as adhesive and pigment, respectively. The influence of chemical composition, surface texture, roughness and thickness on the infrared emissivity was systematically investigated. The detailed results of experimental investigation indicate that the cured composite coatings could possess low emissivity value. Due to reducing infrared absorption and forming uniform and compact char construction, the infrared emissivity decreases obviously. Both the surface roughness and thickness have a critical value, respectively. Too large roughness or thickness would not contribute to the decrease of the emissivity. Moreover, the composite coatings were tested for thermal stability in air to explore the effect of high-temperature environment on the emissivity. The results indicate that the composite coatings, still possessing low emissivity after the test, exhibit favorable thermal ageing and thermal shock resistance.

Hu, Chen; Xu, Guoyue; Shen, Xingmei; Shao, Chunming; Yan, Xiaoxing

2010-03-01

244

Surface properties and wear performances of siloxane-hydrogel contact lenses.  

PubMed

The low surface roughness of disposable contact lenses made of a new siloxane-hydrogel loaded with hyaluronic acid is reported, as studied by atomic force microscopy (AFM). Before the wear, the surface is characterized by out-of-plane and sharp structures, with maximum height of about 10 nm. After a wear of 8 h, evidence of two typical morphologies is provided and discussed. One morphology (sharp type) has a similar aspect as the unworn lenses with a slight increase in both the height and the number of the sharp peaks. The other morphology (smooth type) is characterized by troughs and bumpy structures. Wettability and clinical performances are also discussed, the latter deduced by the ocular-surface-disease index (OSDI). The main finding arising from this work is the indication of correlation between the change of the OSDI before and after wear and the lens surface characteristics obtained by AFM. PMID:23559566

Bettuelli, Michela; Trabattoni, Silvia; Fagnola, Matteo; Tavazzi, Silvia; Introzzi, Laura; Farris, Stefano

2013-11-01

245

Siloxane and Imide-modified Epoxy Resin Cured with Siloxanecontaining Dianhydride  

Microsoft Academic Search

Hydrosilylation of nadic anhydride by tetramethyldisiloxane yielded 5,5’-(1,1,3,3-tetramethyl-1,1,3,3-disiloxanediayl)-bis-norborane-2,3-dicarboxylic anhydride (I), which further reacted with 4-aminophenol to form N,N’-bis(4-hydroxyphenyl)-5,5’-(1,1,3,3-tetramethyl-1,1,3,3-disiloxanediallyl)-binorborane-2,3-dicarboximide (II) reacted with epichlorohydrin to form siloxane- and imide-modified epoxy (i.e. N,N’-diglycidylether-bis-(4-phenyl)-5,5’-(1,1,3,3-tetramethyl-1,1,3,3-disloxanediallyl)-bis-norborane-2,3-dicarboximide (III) (Scheme 1). Various equivalent ratios of III\\/I for 1\\/1, 1\\/0.8 and Bisphenol F epoxy (830LVP DIC Co.)\\/I for 1\\/1, 1\\/0.8 were prepared and cured to produce four crosslinked materials.

Hsun-Tien Li; Mu-Shih Lin; Hsun-Ren Chuang; Ming-Wei Wang

2005-01-01

246

The Polyvinyl Alcohol Sponge Model Implantation  

PubMed Central

Wound healing is a complicated, multistep process involving many cell types, growth factors and compounds1-3. 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 Cellstick1,2. 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 begins1. Later stages of wound healing are best analyzed using the ePTFE model1,4. The Cellstick is a cellulose sponge inside a silicon tube model which is typically used for studying human surgery wounds and wound fluid2. 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 animal5. 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 analysis2,5. 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 process1,2,5. 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 engraftment1,2,6,7. With its great alterability, prior extensive use, and reproducible results, the PVA sponge is an ideal model for many studies1,2. Here, we will describe the preparation, implantation and retrieval of PVA sponge disks (Figure 1) in a mouse model of wound healing.

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

2012-01-01

247

[Pulmonary manifestations of polyvinyl chloride exposure].  

PubMed

There is currently no national data on the effects of polyvinyl chloride (PVC) exposure on pulmonary function. In this study we recruited workers and administrative staff from two PVC plants between July 2008 and July 2009. A questionnaire, pulmonary function tests, carbon monoxide diffusion capacity, and peak flows were recorded. Particulate matter analyses were performed by the Adana Central Laboratory of the Directorate of Occupational Health and Safety. Data were analyzed with SPSS 13.0 software. Nine of the 147 subjects were female. The incidence of a cough was more common in the administrative group. Of the study population, 59.1% were smokers. Tobacco addiction significantly increased cough and dyspnea [OR= 1.10 (1.00-1.20, 95% CI) p= 0.007 and OR= 1.08 (1.02-1.14, 95% CI), p= 0.008, respectively]. Dust exposure was correlated with the incidence of a cough [OR= 0.20 (0.04-0.80, 95% CI) p= 0.008]. The period of work correlated with sputum production [OR= 1.00 (1.00-1.02, 95% CI) p= 0.044]. The FVC% was significantly higher in the administrative group, and FEV1/FVC and DLCO were higher in the exposed group. Tobacco addiction increased the risk of airflow limitation, as evaluated by FEV1/FVC < 70% and FEF25-75 < 50% [OR= 1.15 (1.06-1.25, 95% CI) p= 0.001 and OR= 1.09 (1.02-1.17, 95% CI) p= 0.010, respectively]. Tobacco addiction and increasing duration of work had a negative influence on DLCO in the exposed group (r= -0.270, p= 0.025 and r= -0.210, p= 0.037). In the exposed group PEF variability was significantly greater on workdays, compared with rest days. This study shows that tobacco consumption has a greater affect on the airways than PVC dust exposure. A median of 36 months exposure to PVC dust had no significant impact on pulmonary function parameters, except for DLCO and PEF variability. PMID:21554225

Süyür, Hüseyin; Bayram, Nazan; Ayd?n, Neriman; Uyar, Meral; Gündo?du, Nevhiz; Elbek, Osman

2011-01-01

248

A Single Step Impression Technique of Flabby Ridges Using Monophase Polyvinylsiloxane Material: A Case Report  

PubMed Central

Complete denture fabrication in clinically compromised situations such as flabby ridges is a challenging task for the clinician. Accurate impressioning of these tissues plays a major role in ensuring a well-fitting prosthesis. In this paper, the authors have proposed a newer technique of impression making of the flabby tissues using a combination of readily available newer and older materials to ensure an accurate and easy impression of these tissues.

Pai, Umesh Y.; Reddy, Vikram Simha; Hosi, Rushad Nariman

2014-01-01

249

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

PubMed

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, T(g), 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

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

2012-01-01

250

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

PubMed Central

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.

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

2012-01-01

251

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

Microsoft Academic Search

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

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

2010-01-01

252

Reliability of antagonistic arch impression in dental prostheses: clinical evaluation of different preimpression preparation procedures.  

PubMed

This study compared the influence of different methods of preimpression preparation on the quality of occlusal reproduction in irreversible hydrocolloid impressions. A total of 30 impressions of the lower dental arch of a patient were made with five different preimpression preparation procedures. Stone casts were made and analyzed. Critical comparison showed that the preimpression preparation influenced the quality of the occlusal surface of the cast. Fingerpainting the occlusal surface with fluid hydrocolloid before positioning the loaded impression tray, associated with use of a saliva ejector, reduced the incidence of macroscopic defects on the occlusal surface of the impressions. PMID:8537917

Scotti, R; Lugli, M; D'Elia, A

1995-08-01

253

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

PubMed

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

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

2012-09-01

254

Accuracy and stability of impression materials subjected to chemical disinfection - a literature review.  

PubMed

Disinfection of impressions by immersion or spraying with disinfecting solutions is considered nowadays mandatory for effective infection control. The purpose of this review was to examine existing evidence on the effects that chemical disinfection may have on critical qualities of impressions, namely dimensional accuracy and stability over time. A PubMed search was conducted to include original laboratory research articles written in English, published between 1980 and 2005 in peer-reviewed journals and investigating the effect of chemical disinfection, by immersion or spraying, on the dimensional changes that the impression materials experience after setting. Studies were also sought manually, by tracing the references cited in the retrieved articles. The reports on dimensional changes of disinfected impression materials, although rather numerous, are difficult to compare and analyze because of variations of the experimental design. The investigations broadly agree that the disinfection process does not generally affect the dimensional integrity of the impressions, in spite of the statistically significant differences occasionally found. However, the immersion in the disinfecting solution encourages water absorption phenomena in the case of the so-called hydrophilic impression materials, especially after the long-term immersion. Chemical interactions between impressions and disinfectants may occur, but they do not appear to influence the dimensional behaviour of the former. The overall effect of the disinfection is influenced not only by the changes experienced by the impression per se, but also by the alterations of the acrylic tray containing the impression and of the gypsum product poured in it. PMID:18321265

Kotsiomiti, E; Tzialla, A; Hatjivasiliou, K

2008-04-01

255

An alternative impression technique for implant-retained overdentures with locator attachments.  

PubMed

Locator attachments are commonly used for mandibular implant-retained overdentures. This case report presents an alternative mandibular overdenture impression technique that is pressure free. PMID:20557148

Uludag, Bulent; Cogalan, Kemal; Polat, Serdar

2010-01-01

256

Effect of natural gas odorants on polyvinyl chloride pipe  

Microsoft Academic Search

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

A. R. Knight; A. Verma

1975-01-01

257

Gel Drawn Fibers of Poly(Vinyl Alcohol).  

National Technical Information Service (NTIS)

Semi-crystalline gels of several samples of poly(vinyl alcohol) were made from solutions in which the polymer concentration varied from 2.0 to 15.0%. Entanglement density in the material was in this way reduced from the melt entanglement density. When gel...

P. Cebe D. T. Grubb

1985-01-01

258

Biodegradation of polyvinyl alcohol by a mixed microbial culture  

Microsoft Academic Search

A mixed culture capable of degrading 1gl?1 polyvinyl alcohol (PVA) completely was screened from sludge samples at Pacific Textile Factory, Wuxi, China. This mixed culture had stronger capability of degrading PVA with low polymerization and high saponification than degrading PVA with high polymerization and low saponification. Inorganic nitrogen source was more suitable for the mixed culture to grow and degrade

Jian Chen; Ying Zhang; Guo-Cheng Du; Zhao-Zhe Hua; Yang Zhu

2007-01-01

259

Dielectric Properties and Side-Chain Crystallinity of Polyvinyl Stearate  

Microsoft Academic Search

Measurements of the real (&egr;?) and imaginary (&egr;?) parts of the dielectric constant have been made on polyvinyl stearate at temperatures from ?50° to +80°C and over a frequency range from 100 to 50 000 cps. Although no full relaxation dispersion region has been found in this frequency range, there are indications of the beginnings of a high-frequency dispersion region

Martin G. Broadhurst; Edwin R. Fitzgerald; Anthony J. Bur

1961-01-01

260

Biodegradation of a polyvinyl alcohol-starch blend plastic film  

Microsoft Academic Search

Attempts were made to elucidate the degradation mechanism of a polyvinyl alcohol (PVA)-starch blend plastic. A part of the starch fraction of this plastic was dissolved into an aqueous phase in a control test. Treatment with a PVA-degrading bacterium or enzyme gave a maximal weight loss of approximately 70% and film breakage occurred. Since this plastic contains 40% PVA, it

Tomonori Ishigaki; Yasunori Kawagoshi; Michihiko Ike; Masanori Fujita

1999-01-01

261

Crack formation in polyvinyl chloride coatings on underground pipes  

Microsoft Academic Search

and certain other agents, for a polymeric coating on a tube in the soil, other specific features are also characteristic. Results have previously been presented [1, 2] of a study of polyvinyl chloride coatings kept for a prolonged period under different underground conditions. The investigations were concerned with oxidative processes under the influence of the molecular oxygen of the air

B. I. Borisov; CHLORIDE COATINGS

1975-01-01

262

Plasticized Poly(Vinyl Chloride) Filled with Waste Leather Particles  

Microsoft Academic Search

Waste leather granules were incorporated into poly(vinyl chloride) polymer plasticized with di-octyl phthalate. The blend was prepared by a melt mixing process using a banbury mixer. The rheological behaviour of the mixture was recorded and the filled samples were tested for their physicomechanical properties. It was found that density, wear resistance and Shore D hardness of the specimen increases, whereas

K. Babanas; P. A. Tarantili; A. G. Andreopoulos

2001-01-01

263

Luminescent properties of polyvinyl alcohol — inorganic salt compositions  

NASA Astrophysics Data System (ADS)

Spectral and luminescent properties of polyvinyl alcohol (PVA) films with alkali-halide salt additives are investigated in the present work. The observed effect of increasing the luminescence brightness for the given compositions is explained by the interaction of vacancy defects with polymer macromolecules during their adsorption on salt microcrystals.

Suchkova, E. N.; Pagubko, A. B.

2008-06-01

264

Dynamic Tangent Moduli of Polyvinyl Chloride Subjected to Large Strains.  

National Technical Information Service (NTIS)

The data present in this report describe the changes in the linear dynamic viscoelastic properties of polyvinyl chloride when it has been subjected to large one-dimensional strains. Dynamic tests were carried out on specimens which had undergone large qua...

B. J. Reilly

1971-01-01

265

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...

266

Immobilization of enzymes in photochemically cross-linked polyvinyl alcohol  

Microsoft Academic Search

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

Thomas Uhlich; Mathias Ulbricht; Georg Tomaschewski

1996-01-01

267

From visible to white-light emission by siloxane-capped ZnO quantum dots upon interaction with thiols  

NASA Astrophysics Data System (ADS)

The interaction of thiols (glutathione, cysteine, and cysteamine) with yellow-emitting siloxane-capped ZnO QDs was studied. A gradual enlargement of the PL emission band resulting in white-light emission was observed upon reaction with thiols, while the diameter (ca. 4 nm) and the crystallinity of the dots were not affected. The appearance of broad white-emission was accompanied by a decrease of the photoluminescence quantum yield from 16% to 5-6%. Generation of surface defect states through interaction of the thiols with Zn surface atoms of the dots provoking shrunk of the siloxane capping may be responsible of that broadband emission throughout most of the light spectrum.

Schejn, Aleksandra; Balan, Lavinia; Piatkowski, Dawid; Mackowski, Sebastian; Lulek, Janina; Schneider, Raphaël

2012-06-01

268

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

PubMed

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

Biermann, Ursula; Metzger, Jürgen O

2014-02-01

269

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

Microsoft Academic Search

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

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

2011-01-01

270

Siloxane-modified epoxy resin–clay nanocomposite coatings with advanced anticorrosive properties prepared by a solution dispersion approach  

Microsoft Academic Search

A series of polymer–clay nanocomposite (PCN) materials that consist of siloxane-modified epoxy resin and inorganic nanolayers of montmorillonite (MMT) clay has been prepared through a thermal ring opening polymerization using 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane as a curing agent. These PCN materials at low clay concentration in the form of coating on cold-rolled steel (CRS) were found to be much superior in corrosion protection

Jui-Ming Yeh; Hsiu-Yin Huang; Chi-Lun Chen; Wen-Fen Su; Yuan-Hsiang Yu

2006-01-01

271

Transmission Holographic Gratings Using Siloxane-containing Liquid Crystalline Compounds. Importance of Chemical Structure of Polymer Matrix Components  

Microsoft Academic Search

Siloxane-containing liquid crystalline compounds were found effective to induce distinct phase separation, when combined with multi-functional acrylates, over a wide concentration range from 6 wt % to 20 wt % in the formation of holographic gratings. Use of ring-opening polymerizable bi-functional epoxides as one of the reactive cross-linking matrix component together with penta- or tetra acrylate initiated by 3,3?-carbonylbis(7-diethylaminocoumarin)-diphenyliodonium hexafluorophosphate

Man He; Yeong Hee Cho; Yusuke Kawakami

2006-01-01

272

Purification of landfill biogases from siloxanes by adsorption: A study of silica and 13X zeolite adsorbents on hexamethylcyclotrisiloxane separation  

Microsoft Academic Search

The adsorption capacity on and the desorption from pure activated carbons, silica and NaX zeolite, of hexamethylcyclotrisiloxane (HMCTS or D3, a common siloxane impurity in biogases) has been evaluated in laboratory experiments using synthetic biogas. The adsorption mode of this molecule has also been investigated by FT-IR spectroscopy. HMCTS adsorbs on silica by hydrogen bonding on the surface hydroxyl groups.

Tania Montanari; Elisabetta Finocchio; Irene Bozzano; Gilberto Garuti; Andrea Giordano; Chiara Pistarino; Guido Busca

2010-01-01

273

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

Microsoft Academic Search

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

Selvaganapathi Anbazhagan; Muthukaruppan Alagar; Periyannan Gnanasundaram

274

A video Clinical Global Impression (CGI) in obsessive compulsive disorder.  

PubMed

The Clinical Global Impression scale (CGI) is frequently used in clinical research because of its face validity and ease of use but data on its reliability are scarce. Our goal was to estimate the reliability of the scale and compare reliability between face-to-face and video scoring. We analyzed 50 different video interviews recorded during 5 visits of a crossover trial to study the effect of subthalamic nucleus stimulation. Six specialized clinicians rated the CGI using these videos, providing 300 different ratings. The intraclass correlation was lower at inclusion (0.30 [0.13-0.50]) than at later visits (0.68 [0.61-0.80]). Reliability was not influenced by the patients' stimulation status. The mean of at least two independent evaluations of the video is needed to achieve an ICC greater than 0.8. The video CGI is a valid clinical outcome measure suitable for clinical trials (ClinicalTrials.gov number, NCT00169377). PMID:20621362

Bourredjem, Abderrahmane; Pelissolo, Antoine; Rotge, Jean-Yves; Jaafari, Nematollah; Machefaux, Sebastien; Quentin, Solene; Bui, Eric; Bruno, Nicolas; Pochon, Jean-Baptiste; Polosan, Mircea; Baup, Nicolas; Papetti, François; Chéreau, Isabelle; Arbus, Christophe; Mallet, Luc; du Montcel, Sophie Tezenas

2011-03-30

275

Visco-elastic properties of dental elastomeric impression materials.  

PubMed

The visco-elastic properties of a number of set elastomeric impression materials were determined using a torsional pendulum apparatus, i.e. the real (G1) and imaginary (G2) parts of the complex shear modulus and the mechanical loss tangent (Tan delta). Comparison with published data on tension and compression set for these materials showed that whilst there was no correlation between Tan delta and tension set, there was significant (greater than 99%) correlation with compression set. Treating a permanent set test as the application of a rectangular stress pulse of duration tau, and assuming (i) linear visco-elasticity theory and (ii) that G1 and G2 are independent of frequency. Fourier integral analysis predicts that Tan delta should be proportional to permanent set. Tension set does not conform to this prediction because the deformation is nonlinear. The compression set test is shown to involve shear strains and elastomers generally are Hookean in shear. Whilst the theoretical treatment applies qualitatively, there are major quantitative disparities, the reasons for which are discussed. PMID:3955158

Braden, M; Inglis, A T

1986-01-01

276

Older and Younger Adults' First Impressions From Faces: Similar in Agreement but Different in Positivity  

PubMed Central

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

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

2014-01-01

277

First Impressions Formed of Boys with Learning Disabilities and Attention Deficit Disorder  

Microsoft Academic Search

The present study examined the first impressions that are formed of boys with either learning disabilities (LD), attention deficit disorder (ADD), or both disorders, in an effort to understand better why they are so often unpopular with and rejected by their peers. The intent of the study was to remedy methodological problems of previous first-impression studies to determine whether devaluation

Laura Bickett; Richard Milich

1990-01-01

278

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

ERIC Educational Resources Information Center

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…

Larson, Jeff A.; Tsitsos, William

2013-01-01

279

Evaluation of the accuracy of three techniques used for multiple implant abutment impressions  

Microsoft Academic Search

Statement of problem. Movement of pick-up type impression copings inside the impression material during clinical and laboratory phases may cause inaccuracy in transferring the spatial position of implants from the oral cavity to the master cast. As a consequence, the laboratory technician may fabricate a restoration that requires corrective procedures. Purpose. This in vitro study evaluated the accuracy of 3

Paolo Vigolo; Zeina Majzoub; Giampiero Cordioli

2003-01-01

280

Shake My Hand: Making the Right First Impression in Business with Nonverbal Communications.  

ERIC Educational Resources Information Center

Describes a hand shaking exercise dealing with making a good first impression with nonverbal communication. Asks students to list the characteristics of a good first impression. Discusses how the instructor teaches the students how to shake hands well. Discusses a broader approach regarding learning nonverbal behavior. (SC)

Hiemstra, Kathleen M.

1999-01-01

281

A conceptual framework of impression management: new insights from psychology, sociology and critical perspectives  

Microsoft Academic Search

In this paper we develop a conceptual framework, based on the concepts of rationality and motivation, which uses theories and empirical research from psychology\\/behavioural finance, sociology and critical accounting to systematise, advance and challenge research on impression management. The paper focuses on research that departs from economic concepts of impression management as opportunistic managerial discretionary disclosure behaviour resulting in reporting

Doris M. Merkl-Davies; Niamh M. Brennan

2011-01-01

282

Instructional Strategies for Achieving a Positive Impression in Computer-Mediated Communication (CMC) Distance Education Courses.  

ERIC Educational Resources Information Center

With the rapid development of computer technology in recent years, distance education, and especially computer-mediated communication (CMC), has expanded very quickly. The application of computer technology in education presents many unanswered questions, including issues related to impression formation and impression management in…

Liu, Yuliang; Ginther, Dean W.

283

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

NASA Astrophysics Data System (ADS)

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.

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

2011-12-01

284

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

PubMed

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

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

2011-09-01

285

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

PubMed Central

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.

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

2014-01-01

286

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

PubMed

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

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

2014-04-01

287

High-rate thermomechanical behavior of poly(vinyl chloride) and plasticized poly(vinyl chloride)  

NASA Astrophysics Data System (ADS)

A combined experimental and analytical investigation was carried out in order to develop predictive capabilities for the rate-dependent behavior of poly(vinyl chloride) (PVC) and a dioctyl phthalate (DOP)-plasticized PVC, with focus on predicting the thermo-mechanically coupled behavior under high rates of deformation. The two materials were studied experimentally using both dynamic mechanical analysis (DMA) and compression testing over a wide range of strain rates (10 - 4 s - 1 to 2000 s - 1). DMA testing revealed both an ? -transition and a low-temperature ? -transition (-56circC) in the neat PVC; the incorporation of 20wt% DOP in PVC reduced the ? -transition temperature by 54circC, and also suppressed the ? -transition peak. In compression testing, rate-sensitivity transitions were observed in both the neat PVC and the PVC-20wt% DOP compound. The transition in PVC is attributed to the shift of the ? -transition, whereas the transition in the 20wt% DOP blend is due to the rubbery-to-glassy transition as the deformation rate goes from low to high. A constitutive model for the finite strain deformation of amorphous polymers, introduced elsewhere [1,2] and tailored here for the two material systems of interest, is shown to capture the large deformation stress-strain behavior at all rates tested.

Mulliken, A. D.; Soong, S. Y.; Boyce, M. C.; Cohen, R. E.

2006-08-01

288

Functionalized siloxane-based polymers and network materials for second-order nonlinear optics  

NASA Astrophysics Data System (ADS)

We have developed a new chemical methodology, based on simple acid-base hydrolysis of aminosilanes with molecules containing terminal OH groups, to prepare robust siloxane based polymers and organic-inorganic hybrid network materials for second-order nonlinear optics. First, a variety of polymers containing NLO- active chromophores covalently bound to the siloxane backbones, [-R2Si-(O- SiR2)n-O-(NLO-Chromophore)-O-] n (R = CH3 or CH3/C6H4) and [- R2Si-(O-SiR2)n-O- R'-O-(NLO-Chromophore)-O-] n. (R' = -C6H4-C 6H4- C6H4-), were prepared. Their solubility in common organic solvents, and high thermal stability, imparted ease of thin film preparation, and subsequent poling at high temperatures. These polymers exhibit good second-harmonic generation susceptibilities, and the temporal stabilities of the SHG signals were dependent on the polymer backbone and the molecular structures of the NLO chromophoms. A detailed analysis of their physical properties is reported. Then, a methodology of acid-base hydrolysis was used to produce copolymers containing dimethylsiloxane, imide linkages and NLO-active chromophores. These copolymers were soluble in polar solvents, and possessed high thermal stabilities and glass transition temperatures. Easily fabricated and poled thin films of these polymers exhibited good second-order nonlinear optical susceptibilities with long-term temporal stabilities of the second-harmonic generation signals at room temperature. Finally, an alternative approach, based on the same acid-base hydrolysis technique, to prepare organic-inorganic hybrid network material, was developed. In these hybrid materials, NLO-active chromophores such as Disperse Red 19, a pyridinium. salt based dye, and 1- amino-4-nitrobenzene, were covalently locked into silica networks. The hybrids were soluble, and offered ease of processibility in the preparation of good optical quality thin films. The network materials that are akin to the traditional sol-gel approach were also prepared from the monofunctional NLO chromophore DRI and as expected, were found to be insoluble in common organic solvents. Physical properties of NLO-chromophore incorporated hybrids were tailored by changing the amount of chromophores and water used in hydrolysis, and the type of chromophores. High thermal stability and glass transition temperatures of these hybrids provided effective electric-field poling at high temperatures, and long-term temporal stabilities of the second-harmonic generation signals at room temperature and 80°C.

Jiang, Hongwei

289

The First Impression of Data Sent by Two Martian Rovers  

NASA Astrophysics Data System (ADS)

``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).

Kochemasov, G. G.

290

Cost of Impressed Current Cathodic Protection for Coastal Oregon Bridges  

SciTech Connect

The State of Oregon is using arc-sprayed zinc coatings for anodes in impressed current cathodic protection (ICCP) systems on reinforced concrete coastal bridges. The two lowest bids for four ICCP projects were averaged and converted to 1997 dollars. The total average cost for the ICCP projects was $51.63/ft2 ($555.51/m2) of protected concrete. The cathodic protection part of the ICCP projects average $14.08/ft2 ($151.47/m2), while zinc anode installation cost an average of $7.13/ft2 ($76.67/m2). Oregon's rugged and beautiful coastline is graced with a series of historical arched bridges designed by Conde B. McCullough. McCullough is the internationally recognized architect who designed many of the Oregon Coast Highway (U.S. 101) bridges in the 1920s and 1930s. Many are listed on the National Historic Register. After the expense ($45m) and public outcry associated with the replacement of the historic Alsea Bay Bridge in Waldport, Oregon, the Oregon Department of Transportation began using impressed current cathodic protection (ICCP) to extend the service life of reinforced concrete bridges. Figure 1 visually illustrates the need for such remediation. It shows exposed rebar from underneath the Brush Creek Bridge, which is very representative of the conditions found underneath many coastal Oregon bridges. Four ICCP projects have been funded, put out for bid, and completed. The four projects, their bid closing dates, and their completion dates are the Cape Creek Bridge (1990- 1992), the Yaquina Bay Bridge south arches (1991-1995), the Depoe Bay Bridge (1993-1997), and the Yaquina Bay Bridge south approach (1995-1997). The Cape Creek, Yaquina Bay, and Depoe Bay Bridges are shown in Figs. 2-4. Other ICCP projects are underway on the Oregon coast. In the ICCP systems, arc-sprayed zinc coatings on the concrete surface are anodes that protect the steel rebar. Accelerated laboratory studies at the Albany Research Center have predicted zinc anode service lives of approximately 27 years based on long-term bond strength measurements.1-3 Experience in California4 has documented zinc anode service lives of over 11 years. Both indicate a substantial savings in project costs compared to bridge replacement. For example, the replacement cost of the arc-sprayed sections of the three Oregon bridges is estimated to be $57m, while the four ICCP projects on those bridges have cost $20m. (The $45m to replace the Alsea Bay Bridge was more than simply the replacement cost--it included expanding the bridge to four lanes and making the bridge ''ICCP ready'' by ensuring electrically continuous rebar).

Holcomb, Gordon R.; Cryer, Curtis B.

1998-07-01

291

Micropatterned polyvinyl butyral membrane for acid-base diodes.  

PubMed

Until now, polyvinyl alcohol (PVA) gel cylinders have been used in electrolyte diodes as a connecting element between the acidic and alkaline reservoirs. In this paper, a new connecting element is reported: a breath figure templated polyvinyl butyral (PVB) membrane prepared with dip-coating from a dichloromethane solution of the polymer in a humid atmosphere. The procedure gives a 1.5-2 ?m thick membrane with a hexagonal pattern, the average characteristic length of which is 1 ?m. After an acidic etching, it was found to be a good connecting element. The voltage-current characteristics and dynamic properties of PVA and PVB were measured and compared. The PVB membrane has a faster response to voltage changes than the PVA gel, but in both cases, there was a slow drift in the current that prevented it from reaching a steady state. Reproducible characteristics can be obtained, however, after the current reaches a well-defined quasi-steady state. PMID:20929271

Roszol, László; Lawson, Thuy; Koncz, Viktória; Noszticzius, Zoltán; Wittmann, Maria; Sarkadi, Tamás; Koppa, Pál

2010-11-01

292

Conjunctival impression cytology in non-proliferative and proliferative diabetic retinopathy  

PubMed Central

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

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

2014-01-01

293

In Vitro Evaluation of Dimensional Stability of Alginate Impressions after Disinfection by Spray and Immersion Methods  

PubMed Central

Background and aims The most common method for alginate impression disinfection is spraying it with disinfecting agents, but some studies have shown that these impressions can be immersed, too. The aim of this study was to evaluate the dimensional stability of alginate impressions following disinfecting by spray and immersion methods. Materials and methods Four common disinfecting agents (Sodium Hypochlorite, Micro 10, Glutaraldehyde and De-conex) were selected and the impressions (n=108) were divided into four groups (n=24) and eight subgroups (n=12) for disinfecting by any of the four above-mentioned agents by spray or immersion methods. The control group (n=12) was not disinfected. Then the impressions were poured by type III Dental Stone Plaster in a standard method. The results were ana-lyzed by descriptive methods (mean and standard deviation), t-test, two-way analysis of variance (ANOVA) and Duncan test, using SPSS 14.0 software for windows. Results The mean changes of length and height were significant between the various groups and disinfecting methods. Regarding the length, the greatest and the least amounts were related to Deconex and Micro 10 in the immersion method, respectively. Regarding height, the greatest and the least amounts were related to Glutaraldehyde and Deconex in the im-mersion method, respectively. Conclusion Disinfecting alginate impressions by Sodium Hypochlorite, Deconex and Glutaraldehyde by immersion method is not recommended and it is better to disinfect alginate impressions by spraying of Micro 10, Sodium Hypochlorite, Glutaraldehyde and immersion in Micro 10.

Hamedi Rad, Fahimeh; Ghaffari, Tahereh; Safavi, Sayed Hamed

2010-01-01

294

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

PubMed Central

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.

Amalan, Arul; Ginjupalli, Kishore; Upadhya, Nagaraja

2013-01-01

295

Structure and Properties of Polyvinyl Chloride\\/Halloysite Nanotubes Nanocomposites  

Microsoft Academic Search

Poly(vinyl chloride)(PVC)\\/halloysite nanotubes (HNTs) nanocomposites were prepared by melt blending. The effects of HNT content on the mechanical properties, morphology and rheological properties of the nanocomposites were investigated. The results showed that HNTs were effective in toughening and reinforcing PVC nanocomposites. The notched impact, tensile and flexural strength, and flexural modulus of the nanocomposites were remarkably increased compared to those

Cong Liu; Yuanfang Luo; Zhixin Jia; Shuangquan Li; Baochun Guo; Demin Jia

2011-01-01

296

Investigation of the alumina properties with adsorbed polyvinyl alcohol  

Microsoft Academic Search

The influence of solution pH on the structure of polyvinyl alcohol adsorption layer on the alumina surface was investigated.\\u000a The spectrophotometry, viscosimetry, thermogravimetry, potentiometric titration and microelectrophoresis were applied in experiments.\\u000a These methods enable determination of the following parameters: adsorbed amount of PVA, stability of suspension without and\\u000a with polymer, thickness of its adsorption layers, changes in thermal characteristics of

Ma?gorzata Wi?niewska; Stanis?aw Chibowski; Teresa Urban; Dariusz Sternik

2011-01-01

297

Synthesis of a mesoporous silica hollow microsphere using polyvinyl alcohol  

Microsoft Academic Search

A mesoporous silica hollow microsphere was synthesized in the presence of polyvinyl alcohol for the first time. The synthesized material was characterized by various instrumental techniques such as small-angle X-ray scattering, scanning electron microscopy, transmission electron microscopy, N2 adsorption measurement and Fourier transform infrared spectroscopy. I have succeeded in incorporating an Ultraviolet ray absorber, 2, 2´, 4, 4´ tetrahydroxy benzophenone

N. Venkatathri

2008-01-01

298

Poly(vinyl alcohol)\\/cellulose nanocrystal barrier membranes  

Microsoft Academic Search

In this study, barrier membranes were prepared from poly(vinyl alcohol) (PVOH) with different amounts of cellulose nanocrystals (CNXLs) as filler. Poly(acrylic acid) (PAA) was used as a crosslinking agent to provide water resistance to PVOH. The membranes were heat treated at various temperatures to optimize the crosslinking density. Heat treatment at 170°C for 45min resulted in membranes with improved water

Shweta A. Paralikar; John Simonsen; John Lombardi

2008-01-01

299

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

Microsoft Academic Search

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

Y. Wang; Y.-L. Hsieh

2008-01-01

300

Immobilization of enzyme into poly(vinyl alcohol) membrane  

Microsoft Academic Search

Glucoamylase, invertase, and cellulase were entrapped within poly(vinyl alcohol) (PVA) membrane cross-linked by means of irradiation of ultraviolet light. The conditions for immobilization of glucoamylase were examined with respect to enzyme concentration in PVA, sensitizer (sodium benzoate) concentration in PVA, irradiation time, and membrane thickness. Various characteristics of immobilized glucoamylase were evaluated. Among them, the pH activity curve for the

Kiyokazu Imai; Tomoo Shiomi; Kozo Uchida; Masamitsu Miya

1986-01-01

301

Preparation and properties of microfibrillated cellulose polyvinyl alcohol composite materials  

Microsoft Academic Search

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

Jue Lu; Tao Wang; Lawrence T. Drzal

2008-01-01

302

Migration of plasticizers from plasticized polyvinyl chloride films  

Microsoft Academic Search

The migration of plasticizers [EDOS, di(2-ethyl hexyl) o-phthalate, di-n-butyl o-phthalate] from unfilled and chalk-filled polyvinyl chloride films plasticized with individual and binary plasticizers was\\u000a studied by gravimetric analysis and IR spectroscopy. The intermolecular interaction of components in model systems was studied\\u000a by IR spectroscopy and isothermal calorimetry.

B. I. Lirova; E. A. Lyutikova; A. P. Safronov; T. V. Terziyan; B. A. Berkuta; S. I. Degtyarev; M. I. Prusskii

2006-01-01

303

Manufacturing Process and Application of Pseudo-thermoplastic Polyvinyl Alcohol  

Microsoft Academic Search

Polyvinyl alcohol (PVA) has too close melting and degradation temperatures which causes the failure of temperature control during processing. This study uses glycerin as plasticizing agent to improve high thermo-melting property of PVA so that PVA can be processed at a thermo-melt temperature of 190°C and be equipped with the pseudo-thermoplastic characteristic. The PVA processed with this method is called

Chin-An Lin; Hsiao-Chi Tsai; Te-Hsing Ku

2007-01-01

304

Optical nonlinearity of ZnS-polyvinyl pyrrolidone nanocomposite suspension  

Microsoft Academic Search

ZnS-polyvinyl pyrrolidone nanocomposite was prepared by a simple wet-chemical route. TEM and x-ray diffraction confirmed the formation of nanometre size ZnS particles within the polymer matrix. The average particle size was between 10 and 12 nm. The third-order susceptibility chi(3) of the nanocomposite suspension was measured by employing a single beam z-scan setup with 38 ps laser pulses at 532

Cunxiu Wang; Liusan Guan; Yanli Mao; Yuzong Gu; Junhui Liu; Shishu Fu; Qinghai Xu

2009-01-01

305

Structural-mechanical and thermophysical properties of modified polyvinyl chloride  

NASA Astrophysics Data System (ADS)

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

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

1991-06-01

306

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

PubMed

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

Akuzov, D; Brümmer, F; Vladkova, T

2013-04-01

307

Microscopic observation of unworn siloxane-hydrogel soft contact lenses by atomic force microscopy.  

PubMed

In the present study, samples of lotrafilcon A, balafilcon A, and galyfilcon A contact lenses were observed by atomic force microscopy (AFM) in tapping mode at areas ranging from 0.25 to 400 microm2. Mean roughness (Ra), root-mean-square roughness (Rms) and maximum roughness (Rmax) in nanometers were obtained for the three lens materials at different magnifications. The three contact lenses showed significantly different surface topography. However, roughness values were dependent of the surface area to be analyzed. For a 1 microm2 area, statistics revealed a significantly more irregular surface of balafilcon A (Ra = 6.44 nm; Rms = 8.30 nm; Rmax = 96.82 nm) compared with lotrafilcon A (Ra = 2.40 nm; Rms = 3.19 nm; Rmax = 40.89 nm) and galyfilcon A (Ra = 1.40 nm; Rms = 1.79 nm; Rmax = 15.33 nm). Ra and Rms were the most consistent parameters, with Rmax presenting more variability for larger surface areas. The higher roughness of balafilcon A is attributed to the plasma oxidation treatment used to improve wettability. Conversely, galyfilcon A displays a smoother surface. Present observations could have implications in clinical aspects of siloxane-hydrogel contact lens wear such as lens spoliation, resistance to bacterial adhesion, or mechanical interaction with the ocular surface. PMID:16184533

González-Méijome, José M; López-Alemany, Antonio; Almeida, José B; Parafita, Manuel A; Refojo, Miguel F

2006-02-01

308

The effectiveness of silane and siloxane treatments on the superhydrophobicity and icephobicity of concrete surfaces  

NASA Astrophysics Data System (ADS)

Icy roads lead to treacherous driving conditions in regions of the U.S., leading to over 450 fatalities per year. De-icing chemicals, such as road salt, leave much to be desired. In this report, commercially available silane, siloxane, and related materials were evaluated as solutions, simple emulsions, and complex emulsions with incorporated particulates, for their effectiveness as superhydrophobic treatments. Through the development and use of a basic impact test, the ease of ice removal (icephobicity) was examined as an application of the targeted superhydrophobicity. A general correlation was found between icephobicity and hydrophobicity, with the amount of ice removed on impact increasing with increasing contact angle. However, the correlation was poor in the high performance region (high contact angle and high ice removal.) Polymethylhydrogensiloxane was a top performer and was more effective when used as a "shell" type emulsion with silica fume particulates. An aqueous sodium methyl siliconate solution showed good performance for ice loss and contact angle, as did a commercial proprietary emulsion using a diethoxyoctylsilyl trimethylsilyl ester of silicic acid. These materials have sterically available functional groups that can react or associate with the concrete surface and are potentially film-forming. Materials with less reactive functional groups and a lower propensity to film-form did not perform as well.

Rao, Sunil M.

309

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

NASA Astrophysics Data System (ADS)

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™.

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

2008-11-01

310

Characterization of SiO2 Films Deposited by VUV-CVD Using Organic Siloxane Gases  

NASA Astrophysics Data System (ADS)

Recently, much attention has been paid to novel photochemical vapor deposition using vacuum ultraviolet excimer lamps (VUV-CVD), because thin films can be deposited at room temperature. We show some characterization of films and discuss about the reaction mechanism using organic siloxane gases in VUV-CVD. VUV photons dissociate organic gases into radical reactants of Si-O and impurities such as C-H and O-H in the gas phase. The reactants finally condense on the surface into films included SiO2 and impurities. The reaction is different by adding O2. It is caused by the behaviors of ozone and activated oxygen that VUV photons dissociate O2 and are generated. The deposition efficiency is improved both by the low substrate temperature and the higher light-intensity of an excimer lamp. The film deposition at room temperature in VUV-CVD that either thermal or plasma induced damages are completely avoided must become a novel technique in thin films preparations.

Miyano, Junichi; Yokotani, Atsushi; Kurosawa, Kou

311

Allometric relationships to liver tissue concentrations of cyclic volatile methyl siloxanes in Atlantic cod.  

PubMed

Spatial distribution and relationship of allometric measurements (length, weight and age) to liver concentrations of cyclic volatile methyl siloxanes (cVMS) including octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5) and dodecamethylcyclosiloxane (D6) in Atlantic cod (Gadus morhua) collected near the community of Tromsø in Northern Norway were assessed. These congeners were benchmarked against known persistent polychlorinated biphenyls (PCBs 153 and 180) to assess accumulation behavior of cVMS. D5 was the dominate cVMS detected in all fish livers with lipid normalized concentrations up to 10 times or greater than those observed for PCB 153 and 180. D4 and D6 concentration were negatively correlated with fish length and weight, indicating a greater elimination capacity compared to uptake processes with increasing fish size for these chemicals. These results indicate relationships between allometric measurements and cVMS concentrations may account for concentration variations observed within fish and should be assessed in future studies evaluating cVMS bioaccumulation potential. PMID:24747104

Warner, Nicholas A; Nøst, Therese H; Andrade, Hector; Christensen, Guttorm

2014-07-01

312

Recovery of methane from anaerobic process effluent using poly-di-methyl-siloxane membrane contactors.  

PubMed

This paper demonstrates the potential for recovering dissolved methane from low temperature anaerobic processes treating domestic wastewater. In the absence of methane recovery, ca. 45% of the produced methane is released as a fugitive emission which results in a net carbon footprint of -0.47 kg CO(2e) m(-3). A poly-di-methyl-siloxane (PDMS) membrane contactor was applied to support sweep gas desorption of dissolved methane using nitrogen. The dense membrane structure controlled gaseous mass transfer thus recovery was maximised at low liquid velocities. At the lowest liquid velocity, V(L), of 0.0025 m s(-1), 72% of the dissolved methane was recovered. A vacuum was also trialled as an alternative to sweep-gas operation. At vacuum pressures below 30 mbar, reasonable methane recovery was observed at an intermediate V(L) of 0.0056 m s(-1). Results from this study demonstrate that dissolved methane recovery could increase net electrical production from low temperature anaerobic processes by ca. +0.043 kWh(e) m(-3) and reduce the net carbon footprint to +0.01 kg CO(2e) m(-3). However, further experimental work to optimise the gas-side hydrodynamics is required as well as validation of the long-term impacts of biofouling on process performance. PMID:22277218

Cookney, J; Cartmell, E; Jefferson, B; McAdam, E J

2012-01-01

313

Three-dimensional accuracy of a digitally coded healing abutment implant impression system.  

PubMed

Purpose: This study examined the three-dimensional (3D) accuracy of the Encode Impression System (EN) in transferring the locations of two implants from master models to test models and compared this to the direct impression (DI) technique. The effect of interimplant angulation on the 3D accuracy of both impression techniques was also evaluated. Materials and Methods: Seven sectional polymethyl methacrylate mandibular arch master models were fabricated with implants in the first premolar and first molar positions. The implants were placed parallel to each other or angulated mesiodistally or buccolingually with total divergent angles of 10, 20, or 30 degrees. Each master model was secured onto an aluminum block containing a gauge block, which defined the local coordinate references. Encode healing abutments were attached to the implants before impressions were made for the EN test models; pickup impression copings were attached for the DI test models. For the seven test groups of each impression technique, a total of 70 test models were fabricated (n = 5). The EN test models were sent to Biomet 3i for implant analog placement. The centroid of each implant or implant analog and the angular orientation of the long axis relative to the x- and y-axes were measured with a coordinate measuring machine. Statistical analyses were performed. Results: Impression technique had a significant effect on y distortion, global linear distortion, and absolute xz and yz angular distortions. Interimplant angulation had significant effects on x and y distortions. However, neither impression technique nor interimplant angulation had a significant effect on z distortion. Conclusions: Distortions were observed with both impression techniques. However, the results suggest that EN was less accurate than DI. PMID:25032774

Ng, Simon D; Tan, Keson B; Teoh, K H; Cheng, Ansgar C; Nicholls, Jack I

2014-01-01

314

Self-assembling siloxane bilayer directly on SiO2 surface of micro-cantilevers for long-term highly repeatable sensing to trace explosives  

NASA Astrophysics Data System (ADS)

This paper presents a novel sensing layer modification technique for static micro-cantilever sensors that detect trace explosives by measuring specific adsorption-induced surface stress. For the first time, a method of directly modifying a siloxane sensing bilayer on an SiO2 surface is proposed to replace the conventional self-assembled monolayers (SAMs) of thiols on Au to avoid the trouble from long-term unstable Au-S bonds. For modifying the long-term reliable sensing bilayer on the piezoresistor-integrated micro-cantilevers, a siloxane-head bottom layer is self-assembled directly on the SiO2 cantilever surface, which is followed by grafting another explosive-sensing-group functionalized molecule layer on top of the siloxane layer. The siloxane-modified sensor has experimentally exhibited a highly resoluble response to 0.1 ppb TNT vapor. More importantly, the repeated detection results after 140 days show no obvious attenuation in sensing signal. Also observed experimentally, the specific adsorption of the siloxane sensing bilayer to TNT molecules causes a tensile surface stress on the cantilever. Herein the measured tensile surface stress is in contrast to the compressive surface stress normally measured from conventional cantilever sensors where the sensitive thiol-SAMs are modified on an Au surface. The reason for this newly observed phenomenon is discussed and preliminarily analyzed.

Chen, Ying; Xu, Pengcheng; Li, Xinxin

2010-07-01

315

Comparison of acetate tape impression with squeezing versus skin scraping for the diagnosis of canine demodicosis.  

PubMed

This study compared the sensitivity of acetate tape impression and skin squeezing with that of deep skin scraping for the diagnosis of demodicosis in dogs. Demodex canis was detected in 100% of acetate tape impressions obtained after skin squeezing and in 90% of deep skin scrapings. There was a significant difference (P < 0.001) between the techniques in the total number of mites detected. Acetate tape impression with skin squeezing was found to be more sensitive than deep skin scraping and is an alternative diagnostic method for canine demodicosis. PMID:23106326

Pereira, A V; Pereira, S A; Gremião, I D F; Campos, M P; Ferreira, A M R

2012-11-01

316

DIELECTRIC PROPERTIES OF POLYVINYL ALCOHOL, POLY(METHYL METHACRYLATE), POLYVINYL BUTYRAL RESIN AND POLYIMIDE AT LOW TEMPERATURES  

SciTech Connect

Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI--Kapton\\textregistered). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45K to 350K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and \\pmma\\ dissolved in toluene have the lowest dielectric losses for temperatures lower than $100\\ \\kelvin$. \\Blx\\ and PI have the smallest spread in their breakdown strength data.

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

2008-01-01

317

Dielectric Properties of Polyvinyl Alcohol, Poly(methyl Methacrylate), Polyvinyl Butyral Resin and Polyimide at Low Temperatures  

NASA Astrophysics Data System (ADS)

Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI-Kapton®). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45 K to 350 K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and PMMA dissolved in toluene have the lowest dielectric losses for temperatures lower than 100 K. PVB and PI have the smallest spread in their breakdown strength data.

Tuncer, Enis; Sauers, Isidor; James, D. Randy; Ellis, Alvin R.

2008-03-01

318

A comparison of impression, indentation and impression-relaxation creep of lead-free Sn–9Zn and Sn–8Zn–3Bi solders at room temperature  

Microsoft Academic Search

Creep behavior of Sn–9% Zn and Sn–8% Zn–3% Bi solder alloys was studied by impression, indentation, and impression-relaxation\\u000a tests at room temperature (T > 0.6T\\u000a \\u000a m\\u000a ) in order to evaluate the correspondence of the creep results obtained by different testing techniques, and to evaluate the\\u000a effect of Bi on the creep response of the eutectic Sn–9Zn alloy. Stress exponent values were

R. Mahmudi; A. R. Geranmayeh; H. Noori; H. Khanbareh; N. Jahangiri

2009-01-01

319

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

PubMed Central

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.

2014-01-01

320

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

ERIC Educational Resources Information Center

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

Amorose, Anthony J.; Hollembeak, Jill

2005-01-01

321

Self-promotion as a risk factor for women: The costs and benefits of counterstereotypical impression management  

Microsoft Academic Search

Three experiments tested and extended recent theory regarding motivational influences on impression formation (S. T. Fiske & S. L. Neuberg, 1990; J. L. Hilton & J. M. Darley, 1991) in the context of an impression management dilemma that women face: Self-promotion may be instrumental for managing a competent impression, yet women who self-promote may suffer social reprisals for violating gender

Laurie A. Rudman

1998-01-01

322

A comparison of enhancement techniques for footwear impressions on dark and patterned fabrics.  

PubMed

The use of chemical enhancement techniques on porous substrates, such as fabrics, poses several challenges predominantly due to the occurrence of background staining and diffusion as well as visualization difficulties. A range of readily available chemical and lighting techniques were utilized to enhance footwear impressions made in blood, soil, and urine on dark and patterned fabrics. Footwear impressions were all prepared at a set force using a specifically built footwear rig. In most cases, results demonstrated that fluorescent chemical techniques were required for visualization as nonfluorescent techniques provided little or no contrast with the background. Occasionally, this contrast was improved by oblique lighting. Successful results were obtained for the enhancement of footwear impressions in blood; however, the enhancement of footwear impressions in urine and soil on dark and patterned fabrics was much more limited. The results demonstrate that visualization and fluorescent enhancement on porous substrates such as fabrics is possible. PMID:23786301

Farrugia, Kevin J; Bandey, Helen; Dawson, Lorna; Daéid, Niamh Nic

2013-11-01

323

My Impressions of My American Colleagues. Reflections on My Ukranian Colleagues.  

ERIC Educational Resources Information Center

Presents a Ukrainian teacher's impressions of American English teaching, and an American high school English teacher's reflections about teaching English in the Ukraine. Notes the differences and similarities of teaching English in both countries. (SR)

Tarasova, Olena; Megyeri, Kathy

1999-01-01

324

3D shape measurement of shoeprint impression with structured illumination and fringe pattern analysis  

NASA Astrophysics Data System (ADS)

The shoeprint impressions of suspect left at the crime scene can sometimes tell investigators what type of shoes to be looked for. These shoeprint impressions as one of the important evidence are useful in the detection of criminals. In this paper we propose a novel technique for identifying and analyzing the 3D characteristics of shoeprint impressions. We also design 3D shoeprint impression analysis system based on the combination the 3D shape measurement with structured illumination and fringe pattern analysis. We give a detail discussion on the principle and configuration of the system. Laboratory experiments show the technique is efficient in the detection of shoeprint and in the offering the reference for judicial evidence.

Su, Xianyu; Cao, Yiping; Xiang, Liqun; Chen, Wenjing

2002-06-01

325

Wettability of silicone and polyether impression materials: Characterization by surface tension and contact angle measurements  

Microsoft Academic Search

We report the surface properties of unset and set polymer impression materials by performing surface tension and contact angle measurements. Three types of impression materials were investigated: polyether, addition cure and condensation cure silicones. The high surface tension of about 50mJ\\/m2 for the base and of 38mJ\\/m2 for the accelerator of a polyether system is caused by polar carbonyl and

K. Grundke; S. Michel; G. Knispel; A. Grundler

2008-01-01

326

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

Microsoft Academic Search

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

Nicolai A. Christiansen; Emanuel Tschopp

2010-01-01

327

Clinical success rates for polyether crown impressions when mixed dynamically and statically  

Microsoft Academic Search

The purpose of this study is to compare success rates of dual-viscosity impressions for two types of mixing techniques of\\u000a the polyether elastomeric impression material. Additionally, influencing parameters on the success rates should be evaluated.\\u000a The expectation was that there would be no difference between the success rates for the two mixing techniques. Two centres\\u000a enrolled 290 subjects (727 teeth)

Marc Schmitter; Glen H. Johnson; Clovis Faggion Jr; Christina Klose; Gergo Mitov; Frank P. Nothdurft; Peter R. Pospiech; Peter Rammelsberg; Brigitte Ohlmann; Stefanie Schwarz; Thomas Stober; Petra Schiller; Maria Pritsch

328

An empirical investigation into the effects of web search characteristics on decisions associated with impression formation  

Microsoft Academic Search

It is now common knowledge that information on the World Wide Web is used by people to acquire facts before making decisions—a\\u000a key activity being forming impressions about other people. Given this, an interesting question arises as to whether and how\\u000a such impressions may be biased by the characteristics of the information source itself. For instance, in the case of

Shailaja Venkatsubramanyan; Timothy R. Hill

2010-01-01

329

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

Microsoft Academic Search

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,

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

2008-01-01

330

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

PubMed Central

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.

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

2013-01-01

331

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

PubMed Central

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.

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

2014-01-01

332

Individualized Erlanger KS-Impression Trays for Infants With Cleft Lip and Palate.  

PubMed

Objective : The use of individualized impression trays is required when taking impressions of the maxilla in infants with cleft lip and palate. Custom trays made of plastic such as polymethylmethacrylate, as well as generic, full-arch infant metal trays, have been used up to now. Given the increasing incidence of infectious diseases, the ability to sterilize impression trays for infants with cleft lip and palate is mandatory. Polymethylmethacrylate impression trays are altered in shape and consistency when autoclaved during the sterilization process. Therefore, they have to be fabricated afresh at regular intervals. Methods : Based on modified mold patterns of the available plastic trays, 44 pieces were sorted into four groups of 11 trays in ascending order of size. On these plaster casts, which served as the male part of the template, a 1-mm layer of sheet wax was applied. An optimized ergonomic wax handle was then fitted to the wax plate. Realization in a chromium-cobalt-molybdenum alloy was performed according to the lost wax principle. Conclusions : The sterilizable Erlangen KS-Impression tray (Erlanger KS-Abformlöffel®) is now available in 11 sizes for each of four basic forms. They meet current hygiene guidelines. They can be recommended for routine use when taking impressions in infants with any form of cleft lip and palate without complications. PMID:21269046

Strobel-Schwarthoff, Karin; Hirschfelder, Ursula; Hofmann, Elisabeth

2012-03-01

333

Synthesis and characterization of high-performance polymeric materials: Part I. Silphenylene-siloxanes. Part II. Biodegradable films from gelatins  

NASA Astrophysics Data System (ADS)

Poly(tetramethyl-m-silphenylene-siloxane) (PTMMS) has been successfully synthesized from m-bis(dimethylhydroxysilyl)benzene in a step-growth polymerization using n-hexylamine 2-ethylhexoate as the catalyst. The glass transition temperature of PTMMS is -52 °C, but no melting temperature was detected by DSC. TGA measurements revealed excellent high-temperature properties under nitrogen or air. Random copolymers of tetramethyl-p-silphenylene-siloxane and tetramethyl-m-silphenylene-siloxane were synthesized through condensation copolymerization. Alternating copolymers were prepared through dehydrogenation polymerization. The physical properties can be adjusted from those of a crystalline polymer to those of an amorphous, elastomeric polymer by increasing the amount of the meta comonomer. Thermal studies revealed that these copolymers possess excellent thermal stability. PTMMS has been successfully cross-linked by UV irradiation under air or argon in the presence of benzophenone. Mechanical properties of PTMMS networks were studied by equilibrium stress-strain measurements, and the cross-link density was estimated by means of the Mooney-Rivlin equation. TGA studies revealed that PTMMS elastomers have excellent thermal and thermo-oxidative stabilities. Dehydrogenation polymerization of bis-silanes and disilanols to silphenylenesiloxane polymers through the formation of Si-O-Si bonds as mediated by a rhodium complex was successfully developed. Coordination polymerization using Wilkinson's catalyst provided high molecular weight polymers in high yield at room temperature in an open system. Octamethylcyclo-di(meta-silphenylenesiloxane) (cyclic meta-dimer) was synthesized as the dominant cyclic oligomer product from 1,3--bis(dimethylhydroxysilyl)benzene using 4-dimethylaminopyridine as the catalyst in a dilute THF solution. The X-ray structure of the cyclic meta-dimer was obtained and the Si-O-Si bond angle is 142.1°. The attempted ring-opening polymerization of cyclic meta-dimer to silphenylene-siloxane polymer resulted in a low yield due to the unstrained ring of cyclic meta-dimer. Oligomers of poly(diisopropylsiloxane) with repeating units of up to five have been synthesized. The synthesis of poly(diisopropylsiloxane) is feasible, especially for the heterofunctional polycondensation between silanediols and bisureidosilanes. Cross-linking of gelatin by liquid smoke (dialdehyde) and diisocyanate was successfully carried out. The coagulation technique can be successfully incorporated into the cross-linking and orientation processes to provide a unique method for developing high-performance materials. The resulting films showed excellent tensile strengths in the dry state (as high as 78 MPa) but low tensile strengths when wet.

Zhang, Ruzhi

334

Glasses in the Si O C N system produced by pyrolysis of polycyclic silazane\\/siloxane networks  

Microsoft Academic Search

In this work, polycyclic silazane\\/siloxane networks bearing SiO and SiN bonds were synthesized, via hydrosilylation reaction, from cyclotrisilazane, [CH2CH(CH3)SiNH]3, and cyclotetrasiloxane, [CH3(H)SiO]4, with different SiH:Sivinyl molar ratios. The resulting polymers were pyrolyzed up to 1000°C, in N2 atmosphere, producing SiOCN glasses. The polymer-to-ceramic transformation was studied by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR), and chemical analysis. The 1000–1500°C, high

Marco A. Schiavon; Katia J. Ciuffi; I. Valéria P. Yoshida

2007-01-01

335

Synthesis and Characterization of Organosoluble Polysiloxaneimides Derived from Siloxane-containing Aliphatic Dianhydride and Various Aromatic Diamines  

Microsoft Academic Search

A new siloxane-containing monomer, 5,51-exo-(1,1,3,3,5,5-hexamethyl-trisiloxane -1,5-diyl) bisbicyclo[2,2,1]heptene-2,3-endo-dicarboxylic anhydride (3) was synthesized by the hydrosilylation reaction of 1,1,3,3,5,5-hexamethyl-trisiloxane (1) and cis-5-norbornene-endo-2,3-dicarboxylic anhydride (2). A series of organosoluble polysiloxaneimides (PI 5a-e) was prepared from the dianhydride 3 and several aromatic diamines 4 by a one-step high-temperature polycondensation method and the structures were characterized by IR and NMR. The effects of the main

Shouming Wu; Teruaki Hayakawa; Masa-Aki Kakimoto

2008-01-01

336

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

PubMed

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

Deng, Yu-Luen; Juang, Yi-Je

2014-03-01

337

Amperometric biosensors for glucose, lactate, and glycolate based on oxidases and redox-modified siloxane polymers  

SciTech Connect

Amperometric biosensors based on flavin-containing oxidases undergo several steps which produce a measurable current that is related to the concentration of substrate. In the initial step, the substrate converts the oxidized flavin adenine dinucleotide (FAD) or flavin mononucleotide (FMN) into the reduced form (FADH{sub 2} or FMNH{sub 2}). Because these cofactors are located well within the enzyme molecule, direct electron transfer to the surface of a conventional electrode does not occur to a measurable degree. A common method of facilitating this electron transfer is to introduce oxygen into the system because it is the natural acceptor for the oxidases; the oxygen is reduced by the FADH{sub 2} or FMNH{sub 2} to hydrogen peroxide, which can then be detected electrochemically. The major drawback to this approach is the fact that oxidation of hydrogen peroxide requires a large overpotential, thus making these sensors susceptible to interference from electroactive species. To lower the necessary applied potential, several non-physiological redox couples have been employed to shuttle electrons between the flavin moieties and the electrode. For example, sensors based on the ferrocene/ferricinium redox couple and on electrodes consisting of conducting salts such as TTF-TCNQ (tetrathiafulvalene-tetracyanoquinodimethane) have previously been reported. Electron relays have also been attached directly to the enzyme molecule to facilitate electron transfer. More recently, these studies have been extended to include systems where the mediating redox species are covalently attached to polymers such as poly(pyrrole), poly(vinylpyridine), and poly(siloxane). The present paper describes the development of amperometric biosensors based on flavin-containing enzymes and this latter family of polymeric mediators. 9 refs., 5 figs.

Hale, P.D.; Inagaki, Toru; Lee, Hung Sui; Skotheim, T.A.; Karan, Hiroko I.; Okamoto, Yoshi (Brookhaven National Lab., Upton, NY (USA); Medgar Evers Coll., Brooklyn, NY (USA). Div. of Natural Science and Mathematics; Polytechnic Univ., Brooklyn, NY (USA). Dept. of Chemistry)

1989-01-01

338

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

PubMed

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

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

2013-10-15

339

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

NASA Astrophysics Data System (ADS)

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.

Shah, Bhavesh

340

Cation exchange resins from chemically modified poly(vinyl chloride)  

Microsoft Academic Search

Poly(vinyl chloride) has been modified chemically to a cation exchange resin by halogen displacement reactions with phenol sulfonic acid, bisphenol-A sulfonic acid and phenolpthalein sulfonic acid. Ion-exchange capacity, salt-splitting capacity and pH-titration characteristics of these resins have been evaluated. pH-titration behaviour of these resins is consistent with that of a polyfunctional cation-exchanger having pK1=2 and pK2=9–10 corresponding to -SO3H and

Subrata Moitra; Mukul Biswas

1987-01-01

341

Polyvinyl chloride pneumoconiosis: epidemiological study of exposed workers.  

PubMed

Among 1216 workers who were employed in a polyvinyl chloride production factory and who had had no previous dust exposure elsewhere, 20 cases of pneumoconiosis were found. Chest x-ray abnormalities were characterized by limited profusion, irregular type and low gravity. All 20 workers had been exposed to high PVC dust levels. The chest x-ray changes were observed after a minimum exposure of five years and, in a small percentage of cases, were associated with slight restrictive respiratory function impairments. Moreover, in the whole group of workers 388 cases (31.9%) were found with non-specific x-ray abnormalities mainly related to age and smoking. PMID:469619

Mastrangelo, G; Manno, M; Marcer, G; Bartolucci, G B; Gemignani, C; Saladino, G; Simonato, L; Saia, B

1979-08-01

342

Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol  

SciTech Connect

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.

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

2008-01-01

343

Anomalous ice nucleation behavior in aqueous polyvinyl alcohol solutions  

NASA Astrophysics Data System (ADS)

The effect of polymers on the ice nucleation temperature ( Tf) was studied in a W/O emulsion using ˜5 ?m diameter droplets by differential scanning calorimetry (DSC). Four types of polymers were used. Among them, only polyvinyl alcohol (PVA) showed the additional effect of increasing the Tf of the aqueous solutions. This increase was logarithmic with the concentration of PVA and the difference in molecular weight did not have any significant effect on Tf for the same weight concentration. It was shown that the number of the structural unit (CH 2CHOH) was the key parameter for the increasing degree of Tf.

Ogawa, S.; Koga, M.; Osanai, S.

2009-09-01

344

Catalytic dehydrochlorination of polyvinyl chloride in two-phase systems  

SciTech Connect

The catalytic activity of quaternary ammonium salts (QAS), whose cation and anion structures are different, and the mechanism of catalytic two-phase dehydrochlorination of polyvinyl chloride (PVC) are studied. Under phase-transfer conditions, dehydrochlorination of PVC is shown to proceed at the interface via an ionic mechanism in the presence of quaternary ammonium salts. The catalytic activity of QAS is governed by both the cation lipophilicity and the anion nature and increases as alcohols are introduced into the reaction mixture. The alcohol nature does not influence the extent of the reaction completion, but it does effect the supermolecular structure of the polyacetylene synthesized.

Leplyanin, G.V.; Salimgareeva, V.N.; Sannikova, N.S. [Institute of Organic Chemistry, Ufa (Russian Federation)

1994-11-01

345

Fumes generated during laser processing of polyvinyl chloride (PVC)  

NASA Astrophysics Data System (ADS)

An approach to the assessment of fumes produced in laser material processing is presented. The subsequent design of the fume containment system and sampling strategy is detailed. Polyvinyl chloride (PVC) has been selected for investigation and the complexity resulting from the plethora of additives is discussed. Qualitative results from the preliminary studies of CO 2 laser cutting of PVC are presented together with an appraisal of the problems involved in extending this to quantitative analysis. Benzene, hydrogen chloride (HCl) and methyl methacrylate were found to be the dominant emissions.

Vassie, L. H.; Roach, R. J.; Tyrer, J. R.; Sharp, B. L.

1995-02-01

346

Transient response of microbial communities in a water well field to application of an impressed current.  

PubMed

Deterioration of water wells due to clogging and corrosion over time is a common problem where solutions may be costly and ineffective. Pilot studies have suggested that impressed current or cathodic protection may be used to reduce microbially-induced declines in water well performance. Two water wells in an alluvial aquifer close to the North Saskatchewan River were selected to study the response of subsurface microbial communities to the application of an impressed current as an anti-fouling technology. The treated well was exposed to an impressed current while the untreated well was used as a reference site. Biofilms grown on in situ coupons under the influence of the impressed current were significantly (p < 0.05) thicker (mean thickness = 67.3 ?m) when compared to the biofilms (mean thickness = 19.3 ?m) grown outside the electric field. Quantitative PCR analyses showed significantly (p < 0.05) higher numbers of total bacteria, iron- and nitrate-reducers in the electrified zone. Molecular analysis revealed that the predominant bacteria present in biofilms grown under the influence of the impressed current belonged to Rhodobacter spp., Sediminibacterium spp. and Geobacter spp. In addition to favouring the growth of biofilms, direct microscopic and ICP-AES analyses revealed that the impressed current also caused the deposition of iron and manganese on, and in the vicinity of, the well screen. Together, these factors contributed to rapid clogging leading to reduced specific pumping capacities of the treated well. The study revealed that the impressed current system was not effective as an anti-fouling technology but actually promoted both microbial growth and physical clogging in this aquifer. PMID:23206499

Medihala, P G; Lawrence, J R; Swerhone, G D W; Korber, D R

2013-02-01

347

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

Microsoft Academic Search

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

M. Murugan; V. K. Kokate

2009-01-01

348

In situ Self Cross-Linking of Polyvinyl Alcohol Battery Separators.  

National Technical Information Service (NTIS)

The method disclosed is used to produce a polyvinyl alcohol sheet material wherein the polyvinyl alcohol is substantially free of 1,2 diol units, and has an acetal self cross-linked structure wherein the acetal content is determined by the 1,2 diol conten...

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

1978-01-01

349

Poly(vinyl alcohol) gels for use as tissue phantoms in photoacoustic mammography  

Microsoft Academic Search

Materials for solid photoacoustic breast phantoms, based on poly(vinyl alcohol) hydrogels, are presented. Phantoms intended for use in photoacoustics must possess both optical and acoustic properties of tissue. To realize the optical properties of tissue, one approach was to optimize the number of freezing and thawing cycles of aqueous poly(vinyl alcohol) solutions, a procedure which increases the turbidity of the

Alexei Kharine; Srirang Manohar; Rosalyn Seeton; Roy G. M. Kolkman; René A. Bolt; Wiendelt Steenbergen; Frits F. M. de Mul

2003-01-01

350

Leaching of diethylhexyl phthalate from polyvinyl chloride bags into intravenous cyclosporine solution  

Microsoft Academic Search

The release of diethylhexyl phthalate (DEHP) from flexible polyvinyl chloride containers into intravenous cyclosporine solutions was studied. Intravenous cyclosporine solution or solutions containing the vehicle Cremophor EL and alcohol in dextrose were prepared in an all-glass system and stored in polyvinyl chloride (PVC) bags. Four samples were obtained at different time intervals, and DEHP content was analyzed by gas chromatography.

R. Venkataramanan; G. J. Burckart; R. J. Ptachcinski; R. Blaha; L. W. Logue; A. Bahnson; C. S. Giam; J. E. Brady

1986-01-01

351

Chain length selectivity during the polycondensation of siloxane-containing esters and alcohols by immobilized Candida antarctica lipase B.  

PubMed

We have examined the chain length selectivity for a series of acyl donors by lipase B from Candida antarctica (CalB). CalB accepted aliphatic diesters of C4, C6 and C12 chain lengths equally. The introduction of a carbon-carbon double bond into the C4 esters dramatically lowered the rate constant associated with polymerization highlighting the role of geometry in catalysis; fumarate esters were polymerized at a reduced rate compared to the succinate esters, while the maleate esters were not polymerized above 5% over the course of 24h. A disiloxane-containing diester impeded catalysis by CalB. We examined a series of vinyl siloxane esters and alcohols, and learned that the Z arrangement around the double bond stalled esterification by CalB completely. The distance between the ester carbonyl and the dimethylsiloxy group was shown to be an important factor in mediating catalysis. The rate constants were similar when the methylene spacer was 3, 4, or 5 units in length; beyond 6 methylene units, the rate constants increased. This has been tentatively attributed to the local reduction on the steric bulk when the larger siloxane moiety lies outside of the active site of the enzyme. PMID:24731830

Frampton, Mark B; Zelisko, Paul M

2014-05-10

352

Separation characteristics of phenyl-containing stationary phases for gas chromatography based on silarylene-siloxane copolymer chemistries.  

PubMed

The solvation parameter model is used to characterize the retention properties of five open-tubular column stationary phases (ZB-5 ms, DB-5 ms, DB-XLB, DB-17 ms, and DB-35 ms) based on silarylene-siloxane copolymer chemistries at five equally spaced temperatures over the range 60-140 degrees C. System constant differences and regression models for varied compounds are used to establish the selectivity equivalence of the silarylene-siloxane copolymer stationary phases and to compare their separation characteristics with poly(dimethyldiphenylsiloxane) stationary phases containing a nominally similar concentration of phenyl groups. These studies demonstrate that ZB-5 ms and DB-5 ms are selectivity equivalent. DB-XLB is significantly more dipolar and polarizable than DB-5 ms. In general terms, the silarylenesiloxane copolymer stationary phases are slightly less cohesive and more dipolar and polarizable with similar hydrogen-bond basicity to the poly(dimethyldiphenylsiloxane) stationary phases they were designed to replace. None of the silarylenesiloxane copolymer or poly(dimethyldiphenylsiloxane) stationary phases are hydrogen-bond acidic. Selectivity differences between the two types of stationary phase are temperature dependent and tend to be smaller at higher temperatures within the temperature range studied. Consequently, selectivity differences cannot be globalized without reference to the temperature for the comparison. PMID:16524094

Kiridena, Waruna; Patchett, Cheryl C; Koziol, Wladyslaw W; Ahmed, Hamid; Poole, Colin F

2006-02-01

353

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

NASA Astrophysics Data System (ADS)

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.

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

2011-02-01

354

Synergetic effect of poly(vinyl butyral) and calcium carbonate on thermal stability of poly(vinyl chloride) nanocomposites investigated by TG–FTIR–MS  

Microsoft Academic Search

In order to improve poly(vinyl chloride) (PVC) thermal stability, poly(vinyl butyral) (PVB) matrix and calcium carbonate nanoparticles\\u000a were incorporated in plasticized PVC. Thermal properties of these composites were investigated by thermogravimetry analysis\\u000a coupled with mass spectrometry and Fourier transform infrared spectroscopy (FTIR). This approach highlighted the efficiency\\u000a of both PVB and CaCO3 as HCl scavengers by postponing both the onset

Stéphanie Etienne; Claude Becker; David Ruch; Albert Germain; Cédric Calberg

2010-01-01

355

Radiation-induced network formation in polyvinyl chloride-polyfunctional monomer systems  

NASA Astrophysics Data System (ADS)

Some aspects of the radiation polymerization of allylic polyfunctional monomers in mixtures with polyvinyl chloride have been investigated. The process proceeds through a stepwise formation of the network polymerizate from the polyfunctional monomer, reaction between the polymerizate and polyvinyl chloride and further crosslinking of polyvinyl chloride through reaction with residual allylic double bonds. The initiating radical for the first stage is a low-molecular weight radiolytic product of polyvinyl chloride (apparently, the chloro-radical). At higher initial monomer content the structure formed changes from that of a crosslinked copolymer to that of an interpenetrating network, during irradiation. In the presence of aliphatic plasticizer, the crosslinking density increases in irradiated compositions of polyvinyl chloride and polyfunctional monomers.

Dakin, V. I.

1996-09-01

356

Preparation of poly(vinyl acetate)\\/clay and poly(vinyl acetate)\\/poly(vinyl alcohol)\\/clay microspheres  

Microsoft Academic Search

Poly(vinyl acetate) (PVAc)\\/poly(vinyl alcohol)(PVA)\\/montmorillonite (MMT) clay nanocomposite microspheres with a core\\/shell\\u000a structure have been developed via a suspension polymerization approach. In order to prepare the PVAc\\/MMT and PVAc\\/PVA\\/MMT\\u000a nanocomposite microspheres, which are promising precursor of PVA\\/MMT nanocomposite microspheres, suspension polymerization\\u000a of vinyl acetate with organophilic MMT and heterogeneous saponification were conducted. A quaternary ammonium salt, cetyltrimethylammonium\\u000a bromide, was mixed with

Hye Min Jung; Eun Mi Lee; Byung Chul Ji; Sung Ok Sohn; Han Do Ghim; Hyunju Cho; Young A Han; Jin Hyun Choi; Jae Deuk Yun; Jeong Hyun Yeum

2006-01-01

357

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

SciTech Connect

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.

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

1993-11-05

358

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

PubMed

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

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

2013-09-01

359

Accuracy of a proposed implant impression technique using abutments and metal framework  

PubMed Central

PURPOSE This study compared the accuracy of an abutment-framework (A-F) taken with open tray impression technique combining cementon crown abutments, a metal framework and resin cement to closed tray and resin-splinted open tray impression techniques for the 3-implant definitive casts. The effect of angulation on the accuracy of these 3 techniques was also evaluated. MATERIAL AND METHODS Three definitive casts, each with 3 linearly positioned implant analogs at relative angulations 0, 30, and 40 degrees, were fabricated with passively fitted corresponding reference frameworks. Ten impressions were made and poured, using each of the 3 techniques on each of the 3 definitive casts. To record the vertical gap between reference frameworks and analogs in duplicate casts, a light microscope with image processing was used. Data were analyzed by two-way analysis of variance and the Tukey test. RESULTS The open tray techniques showed significantly smaller vertical gaps compare to closed tray technique (P < .05). The closed tray and the resin-splinted open tray technique showed significantly different vertical gaps according to the angulation of implant (P < .05), but the A-F impression technique did not (P > .05). CONCLUSION The accuracy of the A-F impression technique was superior to that of conventional techniques, and was not affected by the angulation of the implants.

Lee, Hyeok-Jae; Lim, Young-Jun; Kim, Chang-Whe; Choi, Jung-Han

2010-01-01

360

Accuracy of Single-Step versus 2-Step Double-Mix Impression Technique.  

PubMed

Objective. To investigate the accuracy of dies obtained from single-step and 2-step double-mix impressions. Material and Methods. Impressions (n = 10) of a stainless steel die simulating a complete crown preparation were performed using a polyether (Impregum Soft Heavy and Light body) and a vinyl polysiloxane (Perfectim Blue Velvet and Flexi-Velvet) in two consistencies, in one or two (without relief) steps. Accuracy of the stone dies was accessed at a measuring microscope, using a metallic crown with perfect fit to the reference crown preparation. Data were submitted to 2-way ANOVA and Tukey test (? = 0.05). Results. The single-step technique resulted in slightly larger dies, while the 2-step technique without relief produced significantly smaller dies, when compared to the original stainless steel die. Stone dies obtained from 2-step polyether impressions were significantly smaller when compared to dies obtained from 2-step vinyl polysiloxane impressions (Impregum 2-step: -290.94 ± 71.64??m; Perfectim 2-step: -201.86 ± 28.58??m). No significant differences were observed in dies obtained from either polyether or vinyl polysiloxane with the single-step technique (Impregum single-step: 63.52 ± 16.60??m; Perfectim single-step: 79.40 ± 14.11??m). Conclusion. Higher discrepancies were detected for the 2-step impression technique without relief for the investigated materials. PMID:21991468

Franco, Eduardo Batista; da Cunha, Leonardo Fernandes; Herrera, Francyle Simões; Benetti, Ana Raquel

2011-01-01

361

Fabrication of gelatin–siloxane fibrous mats via sol–gel and electrospinning procedure and its application for bone tissue engineering  

Microsoft Academic Search

Our strategy is to design and fabricate biomimetic and bioactive scaffolds that resemble the native extracellular matrix as closely as possible so as to create conducive living milieu that will induce cell to function naturally. In the present study, gelatin\\/siloxane (GS) hybrids were prepared by a sol–gel processing, and electrospinning technique was used to fabricate GS fibrous mats to support

Lei Ren; J?n Wang; Fang-Yu Yang; Lin Wang; Dong Wang; Tian-Xiao Wang; Miao-Miao Tian

2010-01-01

362

Li(+)- and Eu(³+)-doped poly(?-caprolactone)/siloxane biohybrid electrolytes for electrochromic devices.  

PubMed

The sol-gel process has been successfully combined with the "mixed cation" effect to produce novel luminescent and ion conducting biohybrids composed of a diurethane cross-linked poly(?-caprolactone) (PCL530)/siloxane hybrid network (PCL stands for the poly(?-caprolactone) biopolymer and 530 is the average molecular weight in gmol(-1)) doped with a wide range of concentrations of lithium and europium triflates (LiCF(3)SO(3) and Eu(CF(3)SO(3))(3), respectively) (molar ratio of ca. 50:50). The hybrid samples are all semicrystalline: whereas at n = 52.6 and 27.0 (n, composition, corresponds to the number of (C(?O)(CH(2))(5)O) repeat units of PCL(530) per mixture of Li(+) and Eu(3+) ions) a minor proportion of crystalline PCL(530) chains is present, at n = 6.1, a new crystalline phase emerges. The latter electrolyte is thermally stable up to 220 °C and exhibits the highest conductivity over the entire range of temperatures studied (3.7 × 10(-7) and 1.71 × 10(-4) S cm(-1) at 20 and 102 °C, respectively). According to infrared spectroscopic data, major modifications occur in terms of hydrogen bonding interactions at this composition. The electrochemical stability domain of the biohybrid sample with n = 27 spans more than 7 V versus Li/Li(+). This sample is a room temperature white light emitter. Its emission color can be easily tuned across the Commission Internationale d'E?clairage (CIE) chromaticity diagram upon simply changing the excitation wavelength. Preliminary tests performed with a prototype electrochromic device (ECD) comprising the sample with n = 6.1 as electrolyte and WO(3) as cathodically coloring layer are extremely encouraging. The device exhibits switching time around 50 s, an optical density change of 0.15, good open circuit memory under atmospheric conditions (ca. 1 month) and high coloration efficiency (577 cm(2) C(-1) in the second cycle). PMID:21774498

Fernandes, M; Nobre, S S; Rodrigues, L C; Gonçalves, A; Rego, R; Oliveira, M C; Ferreira, R A S; Fortunato, E; Silva, M M; Carlos, L D; Bermudez, V de Zea

2011-08-01

363

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

NASA Astrophysics Data System (ADS)

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

Mabry, Joseph Mark

364

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

NASA Astrophysics Data System (ADS)

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.

Bekele, Solomon

1999-11-01

365

Claw Impressions in the Walls of Modern Mole (Scalopus aquaticus) Tunnels as a Means to Identify Fossil Burrows and Interpret Digging Movements  

Microsoft Academic Search

Casts of the foraging tunnels of eastern American moles (Scalopus aquaticus) show impressions from the moles' mani along the lateral walls. The number of discernable impressions ranges from one to five, each showing two or three long, flat, blunt-ended claws. The size and shape of the impressions matches the claws on the paddle-like manus of S. aquaticus. The impressions are

Katrina E. Gobetz

2005-01-01

366

Two cases of firearm grip impressions on the hands of suicide victims.  

PubMed

Many factors are used to help distinguish firearm suicides from homicides and accidents, including range of fire, location of entrance defects, wound path trajectory, backspatter (blowback), and gunshot residue. Specifically, authors have discussed examination of the hands for backspatter, gunshot residue, cylinder gap effects, iron staining, and trauma as means of supporting a person having held a firearm while committing suicide. Here, we discuss 2 cases where suicidal gunshot wounds were accompanied by unique firearm grip impressions on the hands of the decedents. In 1 case, a "negative"[ impression of a grip pattern was left in a decedent's hand and in another case a grip pattern was left on the decedent's hand in dried blood. Such impressions can be used to provide support for establishing suicide as the manner of death. PMID:20661121

Poulos, Christopher K; Peterson, Brian L

2012-03-01

367

The influence of UV-irradiation on poly(vinyl chloride) modified by poly(vinyl acetate)  

NASA Astrophysics Data System (ADS)

The influence of small amount of poly(vinyl acetate) (PVAC) on poly(vinyl chloride) (PVC) photooxidative degradation was investigated by FTIR, UV-Vis and solid state 13C-NMR spectroscopy. The gel amount formed in exposed samples was estimated gravimetrically. Moreover, surface free energy of PVC+PVAC films was calculated on the base of contact angle measurements. It was found that PVAC decelerates PVC photodegradation, photocrosslinking and photooxidation leading to carbonyl groups formation. This effect is caused by an efficient quenching of macroradicals by low radicals formed in primary photochemical reactions in both polymeric phases. UV-irradiation leads to significant changes of surface properties in all samples studied. In most cases surface free energy decreases with irradiation time but it is caused by an efficient drop of its dispersive component whereas polar component markedly increases due to the formation of functional groups. The mechanism of observed photochemical processes including interactions between both components has been discussed. The influence of sample morphology on the course of photochemical reaction and protection effect induced by carbonyl groups from PVAC was also suggested.

Kaczmarek, Halina; Drag, Renata; ?wi?tek, Ma?gorzata; O?dak, Dagmara

2002-06-01

368

Impression Evaluation and Eye Movement Related to The Characteristic Expression as Elements in Abstract Paintings: Mondrian, Malewitsch and Rothko  

NASA Astrophysics Data System (ADS)

This paper has the purpose to inspect differences regarding impression evaluation and eye movement by comparing characteristic expression as elements in abstract paintings. Malewitsch's paintings which emphasize oblique lines and inclined rectangles elicited impression evaluations such as “hard”, “irritable”, “dynamic” and “exciting”. Mondrian's paintings which emphasize vertical and horizontal line elicited impression evaluations such as “cheerful” and “light”. Rothko's paintings which are obscure outlines elicited impression evaluations such as “mild”, “comfortable”, “relaxing”, “static” and “tedious”. Paintings that have clear vertical and horizontal lines elicit a trend toward higher mean line-of-sight velocity. Paintings that have many distinctive expression elements elicit large frequency of long gaze point. This study indicates that vertical lines, horizontal lines, oblique lines, obscure outlines, and other expression elements in abstract paintings are influencing factors for impression evaluation and eye movement. This suggests that mutual interactions of components that constitute paintings cannot be disregarded. This study is inspection of common impression and perception caused by appreciation of paintings.

Yoshioka, Kiyomi

369

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

PubMed

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

Jones, Simon D; Drake, David J

2013-04-01

370

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

NASA Astrophysics Data System (ADS)

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.

Lee, Hyang-Ok; Lee, In-Bog

2012-09-01

371

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

SciTech Connect

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.

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

372

Making a good impression: (a 'how to' paper on dental alginate).  

PubMed

Approximately 20,000 impressions are made with alginate annually at the University Dental Hospital of Manchester alone, and countless more wherever clinical dentistry is practised. A proportion of these are considered unsatisfactory for clinical use. The reason for these 'failures' is often poor operator technique, rather than an inherent problem of the material. With improved handling of the material and better clinical technique, failures can be avoided. This paper provides an overview of the use of alginate impression material in clinical dentistry. PMID:15881512

Ashley, Martin; McCullagh, Anthony; Sweet, Christopher

2005-04-01

373

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

NASA Technical Reports Server (NTRS)

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.

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

1988-01-01

374

Immobilization of enzyme into poly(vinyl alcohol) membrane  

SciTech Connect

Glucoamylase, invertase, and cellulase were entrapped within poly(vinyl alcohol) (PVA) membrane cross-linked by means of irradiation of ultraviolet light. The conditions for immobilization of glucoamylase were examined with respect to enzyme concentration in PVA, sensitizer (sodium benzoate) concentration in PVA, irradiation time, and membrane thickness. Various characteristics of immobilized glucoamylase were evaluated. Among them, the pH activity curve for the immobilized enzyme was superior to that for the native one, and thermal stability was improved by immobilization with bovine albumin. The apparent Km was larger for immobilized glucoamylase than for the native one, while Vmax was smaller for the immobilized enzyme. Also, the apparent Km appeared to be affected by the molecular size of the substrate. Further, immobilized invertase and cellulase showed good stabilities in repeating usage. 9 references.

Imai, K.; Shiomi, T.; Uchida, K.; Miya, M.

1986-11-01

375

Pulmonary effects of polyvinyl chloride dust exposure on compounding workers.  

PubMed

Spirometry, chest radiography, environmental measurements, and a questionnaire on respiratory symptoms were used to evaluate the effects of exposure to polyvinyl chloride (PVC) dust on 171 Chinese and Malay PVC compounding workers in comparison with an unexposed reference group. Workers with high cumulative PVC dust exposure had a lower forced expiratory volume in 1 s and forced vital capacity, and a higher prevalence of radiological profusion of small opacities. Wheezing or chest tightness was also significantly more frequent in this group. Unlike previous studies, the PVC compounding workers in this study were exposed to only negligible amounts, if any, of vinyl chloride monomer or thermal degradation products of PVC such as hydrogen chloride, phosgene, or chlorine. The conclusion was drawn that a low grade of pneumoconiosis and a small degree of lung function impairment is associated with PVC dust exposure. Reversible airways obstruction is also likely and warrants further investigation. PMID:2047807

Ng, T P; Lee, H S; Low, Y M; Phoon, W H; Ng, Y L

1991-02-01

376

Lung function in workers exposed to polyvinyl chloride dust.  

PubMed

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 both completed the MRC questionnaire on respiratory function and performed simple spirometric tests (forced expiratory volume in one second and forced vital capacity). No differences were found between the three groups after allowance was made for age, height, and smoking. When exposure and smoking effects were considered separately, the latter was shown to be the dominant cause of reduced lung function. In this study work with PVC dust has not produced deleterious effects on ventilatory function. PMID:7426465

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

1980-05-01

377

Electroactive nonionic poly(vinyl alcohol) gel actuator  

NASA Astrophysics Data System (ADS)

A fast (0.8sec), large (>10%) and reversible deformation of Poly(vinyl alcohol) gel (PVA) swollen with dimethyl sulfoxide (DMSO) upon electric field was realized, and the maximum observed strain reached quite high 27% (DP2100). St-PVA gels were found to exhibit more stable and reversible deformation than at-PVA gels. Furthermore, we have studied the macroscopic structure of PVA/DMSO gels and its influence on their strain exhibition. Four differently structured PVA/DMSO gels, monolayer, circular, triple-layered and porous, were prepared. Monolayer gel exhibited the highly reproducible strain behavior. The mechanism of electric actuation of PVA/DMSO gel is proposed. Then a design of gel mechanical switch is shown, which exhibited the fast response to the electric field with a large, stable and reversible stretching deformation.

Popovic, Suzana; Xu, Chunye; Tamagawa, Hirohisa; Taya, Minoru

2001-07-01

378

Speciation of organotins in poly(vinyl chloride) products.  

PubMed

Extraction studies on butyl- and octyltins were conducted with three poly(vinyl chloride) (PVC) product types: clear food container, rigid pipe and flexible membrane. Three solvents, tetrahydrofuran, xylene and methylene chloride were evaluated for extraction efficiency. Methylene chloride extracted more than 97% of the total extractable organotin in two extractions and resulted in the highest recoveries of analytes from all three PVC products. Method detection limits ranged from 0.3 to 0.9 microgram alkyltin/g PVC. The mean precision of the method is 6.8% relative standard deviation. Food industry PVC product samples contained between < 0.8 and 8751 micrograms/g octyltins and < 0.3 and 4.7 micrograms/g butyltins. Butyltins (< 0.9-5985 micrograms/g) were detected in potable water pipe samples. Pipe used in industrial applications contained both butyl- (13-1501 micrograms/g) and octyltins (701-3033 micrograms/g). PMID:8224321

Forsyth, D S; Dabeka, R; Sun, W F; Dalglish, K

1993-01-01

379

Polyvinyl pirrolidone-mediated phase transitions in metastable nanocrystalline cobalt  

NASA Astrophysics Data System (ADS)

Actual and potential applications of metallic cobalt rely on its crystal size- and phase-dependent magnetic properties. On this basis, the present work addresses the synthesis and characterization of nanocrystalline cobalt particles produced through a modified polyol-based approach, which is conducive to the formation of epsilon (?-Co) or hcp-Co phases. Metastable V-Co could be converted into hcp-Co by controlled additions of polyvinyl pirrolidone (PVP) in trimethylene-glycol. XRD evidenced the progressive conversion of the V-Co phase into the hcp-Co phase, as the PVP/Co mole ratio increased from 0 to 11. Magnetic measurements confirmed the strong influence of synthesis conditions on crystal structure and hence, on magnetic properties; the coercivity of the products varied from 134 Oe for V-Co to 752 Oe for the hcp-Co. These values agreed with the soft magnetic nature of epsilon and hard magnetic character of hexagonal phases of cobalt.

Osorio-Cantillo, C.; Perales-Perez, O.; Guinel, M. Jf.

2011-04-01

380

Friction loss in straight pipes of unplasticized polyvinyl chloride.  

PubMed

In order to design proper ductwork for a local exhaust system, airflow characteristics were investigated in straight pipes of unplasticized polyvinyl chloride (PVC). A linear decrease in static pressure was observed downstream at points from the opening of the VU pipes (JIS K 6741) located at distances greater than 10 times the pipe diameter, for velocities ranging between 10.18-36.91 m/s. Roughness inside pipes with small diameters was found to be 0.0042-0.0056 mm and the friction factor was calculated on the basis of Colebrook's equation for an airflow transition zone. An extended friction chart was then constructed on the basis of the roughness value and the friction factor. This chart can be applied when designing a local exhaust system with the ducts of diameters ranging from 40 to 900 mm. The friction loss of the PVC pipe was found to be approximately 2/3 of that of a galvanized steel pipe. PMID:8768669

Iwasaki, T; Ojima, J

1996-01-01

381

Biodegradable thermoplastic composites based on polyvinyl alcohol and algae.  

PubMed

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

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

2008-03-01

382

Vitrification of Polyvinyl Chloride Waste from Korean Nuclear Power Plants  

SciTech Connect

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.

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

383

Optical nonlinearity of ZnS-polyvinyl pyrrolidone nanocomposite suspension  

NASA Astrophysics Data System (ADS)

ZnS-polyvinyl pyrrolidone nanocomposite was prepared by a simple wet-chemical route. TEM and x-ray diffraction confirmed the formation of nanometre size ZnS particles within the polymer matrix. The average particle size was between 10 and 12 nm. The third-order susceptibility ?(3) of the nanocomposite suspension was measured by employing a single beam z-scan setup with 38 ps laser pulses at 532 nm. The results show that the ZnS nanoparticle exhibits saturable absorption and large third-order susceptibility ?(3) (10-9 esu). The difference in optical nonlinearity between the ZnS/PVP suspension and another ZnS nanocomposite was discussed.

Wang, Cunxiu; Guan, Liusan; Mao, Yanli; Gu, Yuzong; Liu, Junhui; Fu, Shishu; Xu, Qinghai

2009-02-01

384

Sulfonated polyvinyl chloride fibers for cation-exchange microextraction.  

PubMed

Polyvinyl chloride (PVC) fiber was derivatized by concentrated sulfuric acid to yield sulfonated PVC (PVC-SO3H). The PVC-SO3H fiber had dual properties as a sorbent, based on cation-exchange and hydrophobicity. In the present study, the novel fiber was used directly as an individual device for extraction purposes in the cation-exchange microextraction of anaesthetics, followed by high-performance liquid chromatography-UV analysis. The results demonstrated that this PVC-SO3H fiber-based microextraction afforded convenient operation and cost-effective application to basic analytes. The limits of detection for four anaesthetics ranged from 1.2 to 6.0 ng/mL. No carryover (because of its disposable usage), and no loss of sorbent phase (which normally occurs in stir-bar sorptive extraction) during extraction were observed. PMID:19682696

Xu, Li; Lee, Hian Kee

2009-09-18

385

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

PubMed

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

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

2014-01-21

386

In vitro considerations in the production of dimensionally accurate earmoulds. I. The ear impression.  

PubMed

As the first part of a study on the fabrication of earmoulds, the dimensional accuracy and stability, as a function of time, of a wide range of polymer-based impression materials has been studied. The results demonstrate that addition cured silicones are the most promising materials in terms of their accuracy and dimensional stability. PMID:2749174

Nolan, M; Combe, E C

1989-01-01

387

First Impressions of HIV Risk: It Takes Only Milliseconds to Scan a Stranger  

PubMed Central

Research indicates that many people do not use condoms consistently but instead rely on intuition to identify sexual partners high at risk for HIV infection. The present studies examined neural correlates for first impressions of HIV risk and determined the association of perceived HIV risk with other trait characteristics. Participants were presented with 120 self-portraits retrieved from a popular online photo-sharing community (www.flickr.com). Factor analysis of various explicit ratings of trait characteristics yielded two orthogonal factors: (1) a ‘valence-approach’ factor encompassing perceived attractiveness, healthiness, valence, and approach tendencies, and (2) a ‘safeness’ factor, entailing judgments of HIV risk, trustworthiness, and responsibility. These findings suggest that HIV risk ratings systematically relate to cardinal features of a high-risk HIV stereotype. Furthermore, event-related brain potential recordings revealed neural correlates of first impressions about HIV risk. Target persons perceived as risky elicited a differential brain response in a time window from 220–340 ms and an increased late positive potential in a time window from 350–700 ms compared to those perceived as safe. These data suggest that impressions about HIV risk can be formed in a split second and despite a lack of information about the actual risk profile. Findings of neural correlates of risk impressions and their relationship to key features of the HIV risk stereotype are discussed in the context of the ‘risk as feelings’ theory.

Renner, Britta; Schmalzle, Ralf; Schupp, Harald T.

2012-01-01

388

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

Microsoft Academic Search

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 undergraduate students (clients) were randomly assigned to one of the

Yoshiko Miwa; Kazunori Hanyu

2006-01-01

389

The effect of a surface wetting agent on void formation in impressions  

Microsoft Academic Search

Statement of problem. Impressions free from voids are important for the fabrication of accurate restorations. Any material or technique that reduces the incidence of bubbles is welcome.Purpose. The aim of this study was to determine whether the use of a surfactant designed for clinical use (Hydrosystem) reduced the number of visible air bubbles on the surface of a range of

Brian J. Millar; Stephen M. Dunne; P. Brett Robinson

1997-01-01

390

Impression-Oriented Music Courseware and Its Application in Elementary Schools  

ERIC Educational Resources Information Center

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…

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

2010-01-01

391

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

ERIC Educational Resources Information Center

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…

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

2014-01-01

392

Physicians' Initial Forensic Impressions of Hypothetical Cases of Pediatric Traumatic Brain Injury  

ERIC Educational Resources Information Center

Objective: To describe physicians' initial forensic impressions of hypothetical cases of pediatric traumatic brain injury (TBI) and to compare the responses of pathologists and pediatricians. Method: A survey was administered to physicians who attended workshops on pediatric TBI; were members of two national internet list serves; and were members…

Laskey, Antoinette L.; Sheridan, Michael J.; Hymel, Kent P.

2007-01-01

393

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

PubMed

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

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

2014-05-01

394

A demonstration of undergraduate students' first impressions and their ratings of pathology.  

PubMed

An interactive team exercise based in the dual topic areas of social and abnormal psychology is described that employs videotaped case studies to sensitize students to the processes by which they form first impressions of other people, and to various issues regarding assessments of mental disorders. Each of three case studies is presented in two parts: Part I simulates a "first impression" condition--involving students' ratings of perceived pathology--by briefly showing only a patient (no soundtrack present), and Part 2 constitutes a "further disclosure" condition by giving more exposure-involving therapists' diagnoses and assessments-of the same patient with both sight and soundtrack presented. Data are reported from 12 introductory psychology classes in which students (N=367) rated the three patients on psychopathology as perceived severity of disorder as compared to the actual assessments (also contained on the videotapes) made by clinical psychologists and psychiatrists. The demonstration is useful in eliciting consistent and predictable first impressions from students, in stimulating classroom discussion about the value and accuracy of person perceptions and first impressions, and in alerting students to problems related to the identification of mental disorders. PMID:12061604

Roeckelein, Jon E

2002-04-01

395

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

Microsoft Academic Search

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

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

2010-01-01

396

Subjects vs. Citizens: Impressment and Identity in the Anglo-American Atlantic  

Microsoft Academic Search

: This article employs the frame of forced migration to understand the impact of British naval impressment, or forced service, on the early American republic. British press gangs not only posed severe risks to the lives and livelihoods of early American seafarers but led Americans of all backgrounds to define the differences between citizenship in a republic and subjecthood in

Denver Brunsman

2010-01-01

397

Subjects vs. Citizens: Impressment and Identity in the Anglo-American Atlantic  

Microsoft Academic Search

This article employs the frame of forced migration to understand the impact of British naval impressment, or forced service, on the early American republic. British press gangs not only posed severe risks to the lives and livelihoods of early American seafarers but led Americans of all backgrounds to define the differences between citizenship in a republic and subjecthood in a

Denver Brunsman

2010-01-01

398

First Impressions Formed of Boys with Learning Disabilities and Attention Deficit Disorder.  

ERIC Educational Resources Information Center

This study examined peers' first impressions formed of elementary-age boys with either learning disabilities (LD), attention deficit disorders (ADD), or both. Physical attractiveness data were gathered, and situational demands varied. Results indicated that boys with either LD or ADD were devalued relative to controls on several dependent…

Bickett, Laura; Milich, Richard

1990-01-01

399

Dispelling the "Old Green Spinach": Impressions of Bibliographic Instruction in Eastern Europe.  

ERIC Educational Resources Information Center

Describes the historical development of libraries and bibliographic instruction (BI) under the Communist system; provides impressions of research libraries visited during a tour of Saint Petersburg (Russia), Kiev (Ukraine), and Budapest (Hungary); and gives examples of BI as it exists in Eastern Europe today. (KRN)

Swensen, Rolf; Garrison-Terry, Suzanne

1994-01-01

400

System constants for the bis(cyanopropylsiloxane)-co-methylsilarylene HP-88 and poly(siloxane) Rtx-440 stationary phases.  

PubMed

The solvation parameter model is used to characterize the retention properties of the bis(cyanopropylsiloxane)-co-methylsilarylene, HP-88, and poly(siloxane), Rtx-440, stationary phases over the temperature range 60-140 degrees C. HP-88 is among the most cohesive, dipolar/polarizable and hydrogen-bond basic of stationary phases for open-tubular column gas chromatography. It has no hydrogen-bond acidity or capacity for electron lone pair interactions. It exhibits similar selectivity to the poly(cyanopropylsiloxane) stationary phase SP-2340. Rtx-440 is a low-polarity, low-cohesion stationary phase with a moderate capacity for dipolar/polarizable and hydrogen-bond base interactions. It has no hydrogen-bond acidity and possesses weak electron lone pair interactions. It has unique selectivity when compared against a system constants database for 28 common stationary phase compositions. Cluster analysis indicated that the poly(cyanopropylphenyldimethylsiloxane) stationary phase containing 6% cyanopropylphenylsiloxane monomer, DB-1301, the poly(dimethyldiphenylsiloxane) stationary phase containing 20% diphenylsiloxane monomer, Rtx-20, the poly(siloxane) stationary phase of unknown composition, DB-624, and DX-1 [a mixture of poly(dimethylsiloxane) and poly(ethylene glycol) 9:1] are the closest selectivity matches in the database. The selectivity of DB-1301 and Rtx-440 are very similar for solutes with weak hydrogen-bond acidity allowing one stationary phase to be substituted for the other with likely success. For strong hydrogen-bond acids, such as phenols, DB-1301 and Rtx-440 exhibit different selectivity. PMID:16038217

Kiridena, Waruna; Patchett, Cheryl C; Koziol, Wladyslaw W; Poole, Colin F

2005-07-22

401

Functional impression and jaw registration: a single session procedure for the construction of complete dentures.  

PubMed

The conventional fabrication of complete dentures involves two separate clinical sessions for functional impression making and jaw registration. The presented method combines both procedures in one session. The aim of this study was to survey the three-dimensional tooth positions in complete dentures with reference to the ridges to establish arbitrary guideline values that could be used for the manufacturing of tooth-position analogue plastic rims on functional impression trays. New complete dentures were fabricated by supervised undergraduate students in the conventional manner for 104 edentulous patients. The position of the maxillary teeth was surveyed in the horizontal plane using the Schmuth 'vizor-measuring plate'. The vertical dimension of occlusion, represented as the distance between opposing ridge areas of the dentures in maximum intercuspation, was measured at different sites by means of a Gutowski gauge. The tooth positions on the dentures varied widely, e.g. the horizontal distances between the incisive papilla and the maxillary incisors was 7.1 +/- 2.3 (3-14) mm. The vertical dimension of occlusion, which is most important in the jaw registration, varied equally with an anterior inter-alveolar distance between 12 and 33 (20.4 +/- 4.0) mm. Arbitrary moulding of the tooth position-analogue plastic rims does not seems to be an ideal method of pre-shaping functional impression trays, because the individual anatomical variation is considerable. Alternatively, the horizontal and vertical tooth positions of functionally and aesthetically pleasing dentures should be measured to pre-shape the rims of functional impression trays in the maxillary and the mandibular jaw. Such trays are a valuable tool for functional impressions and an immediate preliminary jaw registration in the fabrication of new complete dentures. This method allows a first try-in of the full set-up in the third clinical visit without loosing precision. PMID:15189312

Utz, K-H; Müller, F; Kettner, N; Reppert, G; Koeck, B

2004-06-01

402

Toxicological Evaluation of Polyvinyl Acetate (PVA) Emulsion Dust Control Material, May 1973-March 1974.  

National Technical Information Service (NTIS)

The relative toxicity of polyvinyl acetate (PVA) emulsion dust control material was investigated using laboratory animals. PVA emulsion is a mixture composed of a base latex plasticized with cresyl diphenyl phosphate (Santicizer 140) and tetraethylene gly...

M. H. Weeks C. R. Pope

1974-01-01

403

Modification of Poly(vinyl butyral) Coatings Using Bis-silanes (Postprint).  

National Technical Information Service (NTIS)

A commercially available poly(vinyl butyral) (PVB) coating was modified using a combination of 1-10 wt.% bis(trimethoxysilylethyl)benzene and dibutyltin dilaurate as the hydrolysis catalyst. Results of attenuated total reflectance (ATR)-FTIR analysis indi...

M. V. Henley T. L. Metroke

2010-01-01

404

Worker Exposure to Vinyl Chloride in Vinyl Chloride and Polyvinyl Chloride Production and Fabrication.  

National Technical Information Service (NTIS)

In assessment of worker exposure to vinyl-chloride (75014) (VC) and polyvinyl-chloride (9002862) (PVC) was reported. Toxicological data were presented, including acute and chronic animal and human studies, as well as reported worker exposures. Common meth...

J. H. Jones

1977-01-01

405

Effectiveness of mouthrinses and oral prophylaxis on reduction of microorganisms count in irreversible hydrocolloid impression: an in vivo study.  

PubMed

Dental impressions, contaminated with saliva, blood, plaque, are potential source of infection. All impressions should be disinfected after their removal from mouth to prevent cross contamination. Different methods have been tried to disinfect the commonly used irreversible hydrocolloid impression material, but they have been shown to influence the dimensional stability and surface detail of the impression which ultimately affects the precision of the final prosthesis. The aim of this study was to evaluate the efficacy of pre-procedural oral prophylaxis and mouthrinses in reducing the overall microbial load intraorally as well as on alginate impression surface. A total of 60 positive cases selected from 100 subjects who were partially edentulous and above 18 years of age and without medical or pharmacotherapy histories were studied over a period of 18 months, from outpatient clinic of Department of Prosthodontics, GNIDSR. Alginate impressions, before and after prophylaxis were examined microbiologically for the persistence of test microorganisms on the untreated (control group) and the impressions made after treatment. The data were statistically analyzed by the Student t test to assess the effectiveness of the procedure and also the comparative effectiveness of oral prophylaxis and commonly used mouthrinses. The results showed that the impressions were safer when made after oral prophylaxis and/or mouthrinses. PMID:24431795

Dasgupta, Dolanchanpa; Sen, Saibal Kumar; Ghosh, Soumitra; Bhattacharyya, Jayanta; Goel, Preeti

2013-12-01

406

Assessing the effects of three dental impression materials on the isolated sciatic nerve of rat and frog  

Microsoft Academic Search

The effects on nerve tissue of three dental impression pastes were compared in this study. Two of the impression pastes, Examix and Express 3M, contained vinyl polysiloxane while the other, Xanthopren, did not. An in vitro model based on the isolated sciatic nerve of the frog and rat was used. As an indication of the proper functioning of the fibres

A. Andreou; N. Dabarakis; A. Kagiava; E. K. Kosmidis; A. Geronikaki; G. Theophilidis

2007-01-01

407

Marginal and Internal Fit of Cobalt-Chromium Fixed Dental Prostheses Generated from Digital and Conventional Impressions  

PubMed Central

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.

Skjerven, Henrik; Carlsson, Pablo; Karlsson, Stig; Ortorp, Anders

2014-01-01

408

Marginal and internal fit of cobalt-chromium fixed dental prostheses generated from digital and conventional impressions.  

PubMed

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

Svanborg, Per; Skjerven, Henrik; Carlsson, Pablo; Eliasson, Alf; Karlsson, Stig; Ortorp, Anders

2014-01-01

409

Growth control of ice crystals by poly(vinyl alcohol) and antifreeze protein in ice slurries  

Microsoft Academic Search

Effect of poly(vinyl alcohol) (PVA) in inhibiting an increase in ice crystal size in isothermal ice slurries was investigated, and then compared with the effect of an antifreeze protein (AFP), NaCl, and three other polymers, namely, poly(ethylene glycol), poly(vinyl pyrrolidone), and poly(acrylic acid). First, ice slurries, in which the initial size distribution of ice crystals was known, were isothermally preserved

Takaaki Inada; Poly Rani Modak

2006-01-01

410

Viscometric study of poly(vinyl chloride)\\/poly(vinyl acetate) blends in various solvents  

Microsoft Academic Search

The intermolecular interactions between poly(vinyl chloride) (PVC) and poly(vinyl acetate) (PVAc) in tetrahydrofuran (THF), methyl ethyl ketone (MEK) and N,N?-dimethylformamide (DMF) were thoroughly investigated by the viscosity measurement. It has been found that the solvent selected has a great influence upon the polymer–polymer interactions in solution. If using PVAc and THF, or PVAc and DMF to form polymer solvent, the

Yuchuan Zhang; Jiasheng Qian; Zhuo Ke; Xiangcheng Zhu; Hong Bi; Kangming Nie

2002-01-01

411

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

Microsoft Academic Search

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

Jeong Hyun Yeum

2011-01-01

412

Pseudomonas fluorescens lipase immobilization on polysiloxane–polyvinyl alcohol composite chemically modified with epichlorohydrin  

Microsoft Academic Search

The technique based on sol–gel approach was used to generate silica matrices derivatives by hydrolysis of silane compounds. The present work evaluates a hybrid matrix obtained with tetraethoxysilane (TEOS) and polyvinyl alcohol (PVA) on the immobilization yield of lipase from Pseudomonas fluorescens. The resulting polysiloxane–polyvinyl alcohol (POS–PVA) matrix combines the property of PVA as a suitable polymer to retain proteins

J. C. Santos; A. V. Paula; G. F. M. Nunes; H. F. de Castro

2008-01-01

413

Hybrid material polyvinyl alcohol-copper oxide and its electrical properties  

NASA Astrophysics Data System (ADS)

The hybrid material polyvinyl alcohol-copper oxide was produced by the thermal decomposition of polyvinyl alcohol-copper hydroxide complex compound. It was analyzed by means of XRD, UV-VIS, IR, and Raman spectroscopy. It was concluded that the most part of copper oxide has an amorphous structure and consists of -(Cu-O) n - chains. The electrical properties of this material were investigated at direct and alternating current in 80-375 K temperature range.

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

2012-08-01

414

Poly(vinyl alcohol) Membranes Having an Integrally Skinned Asymmetric Structure  

Microsoft Academic Search

Poly(vinyl alcohol) membranes, having integrally skinned asymmetric structures, were prepared by using 2-propanol and cosolvent composed of N-methyl-2-pyrrolidone and water, by phase inversion processes. In this work, the effects of cosolvent on the formation of integrally skinned structure of the asymmetric poly(vinyl alcohol) membranes were investigated and discussed from the morphological point of view. Experimental result indicated that the resulting

Sang-Gyun Kim; Kew-Ho Lee

2009-01-01

415

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

Microsoft Academic Search

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

Jian Xu; Zhen-Liang Xu

2002-01-01

416

Effects of nanoscale dispersion in the dielectric properties of poly(vinyl alcohol)-bentonite nanocomposites  

Microsoft Academic Search

We investigate the effects of clay proportion and nanoscale dispersion in the dielectric response of poly(vinyl alcohol)-bentonite nanocomposites. The dielectric study was performed using the thermally stimulated depolarization current technique, covering the temperature range of the secondary and high-temperature relaxation processes. Important changes in the secondary relaxations are observed at low clay contents in comparison with neat poly(vinyl alcohol) (PVA).

María C. Hernández; N. Suárez; Luis A. Martínez; José L. Feijoo; Salvador Lo Mónaco; Norkys Salazar

2008-01-01

417

Fabrication of Customized Sectional Impression Trays in Management of Patients with Limited Mouth Opening: A Simple and Unique Approach  

PubMed Central

Impression making is not only important but is also the most significant step in the fabrication of any fixed or removable prosthesis. Proper impression making may be hindered by certain pathologic conditions. Reduced mouth opening is one of the common mechanical obstructions for proper orientation of the impression tray in the patient's mouth. In patients with trismus induced by submucous fibrosis, the procedure may be even more difficult to carry out because of reduced tissue resiliency and obliteration of vestibular spaces. Use of sectional trays offers one of the alternatives to overcome the problem of restricted mouth opening. Fabrication of customized impression trays according to the patient dentition improves the accuracy of impression making. The present case reports describe the fabrication of sectional custom trays designed for dentulous patients with chronic tobacco-induced submucous fibrosis.

Krishna CH, Vamsi; Mahendranadh Reddy, K.; Gupta, Nidhi; Mahadev Shastry, Y.; Chandra Sekhar, N.; Aditya, Venkat; Reddy, G. V. K. Mohan

2013-01-01

418

A survey of the methods of disinfection of dental impressions used in dental hospitals in the United Kingdom.  

PubMed

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

Blair, F M; Wassell, R W

1996-05-25

419

Dielectric dispersion study of coexisting phases of aqueous polymeric solution: Poly(vinyl alcohol) + poly(vinyl pyrrolidone) two-phase systems  

Microsoft Academic Search

The complex dielectric constant ??(?)=???j??, electric modulus M?(?)=M?+jM?, impedance Z?(?)=Z??jZ? and ac conductivity dispersion behaviour of 5, 10 and 15wt% concentration aqueous solutions of poly(vinyl alcohol) (PVA) (14?000 and 77?000gmol?1) and poly(vinyl pyrrolidone) (PVP) (24?000, 40?000 and 360?000gmol?1) and their binary mixtures were investigated in the frequency range 20Hz to 1MHz at 25°C. Analysis of dielectric constant values confirms that

R. J. Sengwa; Sonu Sankhla

2007-01-01

420

Clinical success rates for polyether crown impressions when mixed dynamically and statically.  

PubMed

The purpose of this study is to compare success rates of dual-viscosity impressions for two types of mixing techniques of the polyether elastomeric impression material. Additionally, influencing parameters on the success rates should be evaluated. The expectation was that there would be no difference between the success rates for the two mixing techniques. Two centres enrolled 290 subjects (727 teeth) into the trial. Patients were randomized for the two types of mixing techniques. One step, dual-viscosity impressions were made with either statically mixed Impregum Soft tray material (SAM) or dynamically mixed Impregum Penta H DuoSoft (DMM). Low viscosity Impregum Garant L DuoSoft was used for both groups. Gingival displacement involved the use of two braided cords. Full-arch trays were used exclusively. Both critical defects and operator errors were assessed for the first impression taken by trained dentists. The primary outcome was impression success. For comparison of the two mixing techniques, the odds ratio for success and the corresponding one-sided 95% confidence interval was calculated by a logistic regression model. To account for the dependence between several teeth within one patient, the method of general estimating equations was used. The overall impression success rate was 35.4%. Both mixing techniques showed equal success rates indicated by an OR of 1.0 and a lower limit of the one-sided 95% confidence interval of 0.71. Using this result to develop the corresponding interval for the difference, it could be shown that the success rate using SAM was at most 8.2% lower than that when using DMM with a probability of 95%. Multivariate logistic regression analysis of other potential influencing factors showed position of finish line (p = 0.008, supra compared to mixed), blood coagulation disorder (p = 0.021) and the level of training of the clinician (student vs dentist, p=0.008) to have an independent influence on the success rate. Dynamic mechanical mixing and the new static mixing of polyether tray material showed nearly equal success rates in the study even though success rates were comparatively low (DMM, 35.3%; SAM, 35.4%). PMID:21611728

Schmitter, Marc; Johnson, Glen H; Faggion, Clovis; Klose, Christina; Mitov, Gergo; Nothdurft, Frank P; Pospiech, Peter R; Rammelsberg, Peter; Ohlmann, Brigitte; Schwarz, Stefanie; Stober, Thomas; Schiller, Petra; Pritsch, Maria

2012-06-01

421

Lasting Impression  

ERIC Educational Resources Information Center

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,…

Kennedy, Mike

2006-01-01

422

Good Impressions  

ERIC Educational Resources Information Center

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…

Renner, Jason

2010-01-01

423

Modern Impressions  

ERIC Educational Resources Information Center

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…

Simkus, Joyce

2010-01-01

424

Dinosaur Impressions  

Microsoft Academic Search

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

Philippe Taquet

1998-01-01

425

Analytical application of poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane} as a QCM coating for DMMP detection  

Microsoft Academic Search

A new material—poly{methyl[3-(2-hydroxy-3,4-difluoro)phenyl]propyl siloxane}(PMDFPS) sensitive to toxic organophosphate vapor was synthesized with 2,3-difluorophenol, allyl bromide and poly (methyl hydrosiloxane) as raw materials, via O-alkylation, Claisen rearrange reaction and hydrosilylation reaction. This novel material was then coated on a quartz crystal microbalance (QCM) to investigate its gas sensitive properties to the nerve agent simulant dimethyl methylphosphonate (DMMP) vapor, as well as

Wei He; Zhongxiang Liu; Xiaosong Du; Yadong Jiang; Dan Xiao

2008-01-01

426

Application of AB-crosslinked polymers composed of styrene\\/isoprene–siloxane copolymers to pervaporative removal of volatile organic compounds from water  

Microsoft Academic Search

Separation and transport properties of AB membranes during pervaporation of water–methyl acetate (water–MeAc) and water–methyl tert-butyl ether (water–MTBE) mixtures were investigated. Membranes were prepared from AB-crosslinked copolymer composed of elastomeric oligo or poly H-polysiloxanes and glassy styrene\\/isoprene prepolymer. Results showed that the properties depended on the siloxane content in the membrane. The pervaporation properties of AB membranes were much better

Wojciech Kujawski; Jochen Kerres; Renata Roszak

2003-01-01

427

Side chain liquid crystalline polymers containing siloxane spacer: 7. Syntheses and properties of polyimides and polyamides containing a mesogenic side chain connected with a disiloxane linkage  

Microsoft Academic Search

Preparations of polyimides and polyamides containing a mesogenic group in the side chain connected with a siloxane bond in the spacer component were carried out. A 3,5-diaminobenzyloxy-type monomer having a mesogen consisting of a p'-substituted biphenyl benzoate group was prepared by means of hydrosilylation of 1-[3-43,5-dinitrobenzyloxy)propyl]-1,1,3,3-tetramethyldisiloxane with a mesogenic allyloxy compound, followed by catalytic reduction of the two nitro groups.

Yu Nagase; Yuriko Takamura; Eiichi Akiyama

1995-01-01

428

Reinforcement of a poly(dimethyl siloxane) mold with high aspect ratio microstructures via a gas-liquid phase sol-gel process  

Microsoft Academic Search

A gas-liquid phase sol-gel process was proposed to reinforce a poly(dimethyl siloxane) (PDMS) mold with high aspect ratio microstructures (HARMs) for micromolding. Unlike the conventional sol-gel process or in situ precipitation of silicate nanoparticles (SiO2) inside the PDMS network, the vapor of water and aminomethyl propanol-95 permeated through the PDMS which was pre-soaked with tetraethoxy silane (TEOS), leading to the

Zih-Jian Jheng; Yan-Chao Fang; Kuo-Feng Lo; Yi-Je Juang

2009-01-01

429

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

Microsoft Academic Search

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

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

2004-01-01

430

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)

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.

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

2013-11-01

431

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)

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.

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

432

Automatic comparison and evaluation of impressions left by a firearm on fired cartridge cases.  

PubMed

Recent years have been characterized by a series of publications in the field of firearms investigation questioning the reliability and objectivity of such examination. This research investigates new solutions to decrease the subjective component affecting the evaluation that follows the comparison of impressions left by a firearm on the surface of spent cartridge cases. An automatic comparison system based on 3D measurements has been developed and coupled to a bivariate evaluative model allowing assigning likelihood ratios. Based on a dataset of 79 pistols (all SIG Sauer 9 mm Luger caliber), the system shows a very high discriminating power and the LRs that it provides are very indicative of the true state under both the prosecution and the defense propositions. For example, likelihood ratios exceeding a billion are predominantly obtained when impressions originating from the same source are compared. The system is also characterized by relatively low rates (? 1%) of misleading evidence depending on the firearm considered. PMID:24502645

Riva, Fabiano; Champod, Christophe

2014-05-01

433

Cyclosporine Effects on Clinical Findings and Impression Cytology Specimens in Severe Vernal Keratoconjunctivitis  

Microsoft Academic Search

Purpose: To investigate the possible effects of topical cyclosporine eye drops 2% (CsA) on conjunctival immune cells obtained by impression cytology technique and to determine the clinical relevance of this effect if present. Methods: Ten consecutive patients with severe, resistant, and active vernal keratoconjunctivitis (VKC) were included in this study. All of them were treated with 2% of topical CsA

Avni Murat Avunduk; Mustafa Cihat Avunduk; Hidayet Erdöl; Zerrin Kapicioglu; Nurettin Akyol

2001-01-01

434

Gordon and Mike's ICT Podcast: Apple iPad First Impression Podcast  

NSDL National Science Digital Library

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.

Qaissaunee, Michael; Snyder, Gordon F.

2010-11-03

435

The effect of employee behavior on brand personality impressions and brand attitudes  

Microsoft Academic Search

This research examines how consumers update their brand personality impressions and brand attitudes after interacting with\\u000a one of the brand's employees. Drawing on stereotyping theory, the author develops a framework that proposes that the impact\\u000a of an employee's behavior depends on how the employee is categorized. When the employee is considered primarily as an exemplar\\u000a of the brand's workforce, his

Daniel Wentzel

2009-01-01

436

The Relationship Between College Students' Self-Reports of Class Participation and Perceived Instructor Impressions  

Microsoft Academic Search

The purpose of this investigation was to identify the extent to which college students' self-reports of their in-class participation are related to their impressions of instructors (i.e., credibility, attractiveness, and homophily). Participants were 223 undergraduate students enrolled in an introductory communication course at a large Mid-Atlantic university. Students' self-reports of their in-class participation were positively correlated with perceived instructor social

Scott A. Myers; Sean M. Horan; Carrie D. Kennedy-Lightsey; Paul E. Madlock; Robert J. Sidelinger; Kerry Byrnes; Brandi Frisby; Daniel H. Mansson

2009-01-01

437

Applicant Impression Management: Dispositional Influences and Consequences for Recruiter Perceptions of Fit and Similarity  

Microsoft Academic Search

This study investigates how applicant characteristics influence the use of impression management (IM) tactics in interviews, and how these behaviors affect interviewer perceptions of person-job fit (P-J fit) and applicant-interviewer similarity. Results from 72 applicants demonstrated that extraverted applicants made greater use of self-promotion during their interviews, while agreeableness was associated with non-verbal cues. Self-promotion was the IM tactic most

Amy Kristof-Brown; Murray R. Barrick; Melinda Franke

2002-01-01

438

Applicant Impression Management: Dispositional Influences and Consequences for Recruiter Perceptions of Fit and Similarity  

Microsoft Academic Search

This study investigates how applicant characteristics influence the use of impression management (IM) tactics in interviews, and how these behaviors affect interviewer perceptions of person–job fit (P–J fit) and applicant–interviewer similarity. Results from 72 applicants demonstrated that extraverted applicants made greater use of self-promotion during their interviews, while agreeableness was associated with non-verbal cues. Self-promotion was the IM tactic most

Melinda Franke

2002-01-01

439

Proposal of the Kawaii Search System Based on the First Sight of Impression  

Microsoft Academic Search

\\u000a We propose a blog search engine called “Kawaii Search” (where Kawaii means pretty) to search blogs based on the impression\\u000a of their text on a printing surface, considering factors such as the format and layout of text and density of words. Particularly\\u000a in Japan, blogs reveal the personality characteristics of users depending on how they place their text. For example,

Kyoko Hashiguchi; Katsuhiko Ogawa

440

Mini-invasive impression techniques in fixed prothesis: an alternative to traditional procedures  

PubMed Central

SUMMARY The object of our work is the illustration of an alternative technique in the impress survey in fixed prosthesis. This method conceived from Doctor Casartelli, allowed us to utilize this technology in the day-to-day activity eliminating also the anaesthetic use, so give the possibility to operate patients with anticoagulant therapy. Moreover the mini-invasive techniques allow a lowering recessions, best tolerability from the patients, less pain and postoperative inflammation, “restitutio ad integrum” of tissue without morphological modifications.

BONINO, M.; DE VICO, G.; SPINELLI, D.; CONTI, I.; OTTRIA, L.; BARLATTANI, A.

2010-01-01

441

Craniocervical growth collision: another explanation of the Arnold-Chiari malformation and of basilar impression  

Microsoft Academic Search

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)

M. Roth

1986-01-01

442

Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited  

NASA Astrophysics Data System (ADS)

A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.

Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G.; Manohar, Srirang

2011-07-01

443

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

PubMed

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

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

2014-05-14

444

Electrospun chitosan/polyvinyl alcohol nanofibre mats for wound healing.  

PubMed

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

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

2014-04-01

445

Uncommon photoluminescence behavior of Fe3+ doped polyvinyl alcohol films  

NASA Astrophysics Data System (ADS)

In this paper, pure and Fe3+ doped polyvinyl alcohol (PVA) films, using FeCl3, are prepared by a solution casting method. The effect of Fe3+doping on the photoluminescence (PL) behavior of PVA is investigated in the temperature range from 10 to 300 K. At 300 K, the PL spectrum of pure PVA is formed by two bands I1and I2. These two bands can be connected with trap states inside the band gap. The PL intensities of I1 and I2 are found to increase with increasing the doping content. The temperature dependence of the PL intensity for neat PVA shows a decrease in the PL intensity with temperature assigned to the phonon diffusion by the photo-created electron–hole pairs. However, the PL studies of some doped samples containing an important amount of iron reveal an uncommon behavior of their PL intensity which rises with temperature. Two suggestions are given to explain such a behavior. The first is related to the change in the levels nature inside the bandgap and the second is correlated to the (I1–I2) energy.

Khalifa, N.; Souissi, A.; Attar, I.; Daoudi, M.; Yakoubi, B.; Chtourou, R.

2013-12-01

446

Dielectric breakdown during Cs+ sputtering of polyvinyl chloride  

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

447

The development and characterization of degradable poly(vinyl ester) and poly(vinyl ester)/PEO block copolymers  

NASA Astrophysics Data System (ADS)

The development of biodegradable materials is a challenging and important problem in polymer science. A review of the state of the art in degradable materials is presented, which reveals that current biodegradable materials do not exhibit the thermal or mechanical properties necessary for widespread applications. One strategy for toughening polymeric materials, which has previously been applied to non-degradable thermoplastics and thermoplastic elastomers, is the formation of block copolymers. Poly(vinyl esters) (PVE) homopolymers are known to have a wide range of properties, but PVE block copolymers comprise a class of inexpensive and (bio)degradable materials that were previously unknown. Therefore, the synthesis and properties of these block copolymers were explored in an effort to develop robust degradable materials. This thesis research probes the reaction conditions necessary for the reversible-addition fragmentation chain transfer (RAFT) polymerization and chain extension reactions of vinyl ester monomers. PVE di- and triblock copolymers are synthesized and studied, and the triblock copolymers display extremely poor toughness due to their relatively low molecular weights in light of the high entanglement molecular weight of the poly(vinyl acetate) center block. Attempts to improve the mechanical properties of these materials focus on the incorporation of poly(ethylene oxide) (PEO) as a low entanglement molecular weight and biocompatible center block in PVE-containing triblock copolymers. Depending on the choice of PVE endblocks and the overall polymer composition, crystallization of the PEO block can be controlled, confined, or inhibited. Polymers in which PEO crystallization is completely inhibited exhibit enhanced mechanical properties and behave as weak thermoplastics. In order to understand the relationship between the inhibition of PEO crystallization and the mechanical properties of PVE/PEO materials, these polymers were studied using dynamic mechanical spectroscopy, wide angle X-ray scattering, small angle X-ray scattering, differential scanning calorimetry, and uniaxial tensile tests. By combining insights gained from these techniques, a complex picture emerges that explains the enhanced mechanical properties of these materials based on the type and location of thermal transitions, amorphous PEO entanglements, and the strain-induced crystallization of PEO. This work represents an important step toward developing robust materials with tunable properties containing (bio)degradable components.

Lipscomb, Corinne Elizabeth

448

The influence of impression management scales on the Personality Assessment Inventory in the epilepsy monitoring unit.  

PubMed

The Somatic Complaints scale (SOM) and Conversion subscale (SOM-C) of the Personality Assessment Inventory perform best in classifying psychogenic non-epileptic seizures (PNES) from epileptic seizures (ES); however, the impact of positive impression management (PIM) and negative impression management (NIM) scales on SOM and SOM-C classification has not been examined. We studied 187 patients from an epilepsy monitoring unit with confirmed PNES or ES. On SOM, the best cut score was 72.5 T when PIM was elevated and 69.5 T when there was no bias. On SOM-C, when PIM was elevated, the best cut score was 67.5 T and 76.5 T when there was no bias. Negative impression management elevations (n=9) were too infrequent to analyze separately. Despite similarities in classification accuracy, there were differences in sensitivity and specificity with and without PIM, impacting positive and negative predictive values. The presence of PIM bias generally increases positive predictive power of SOM and SOM-C but decreases negative predictive power. PMID:23159377

Purdom, Catherine L; Kirlin, Kristin A; Hoerth, Matthew T; Noe, Katherine H; Drazkowski, Joseph F; Sirven, Joseph I; Locke, Dona E C

2012-12-01

449

Flow cytometry in conjunctival impression cytology: a new tool for exploring ocular surface pathologies.  

PubMed

Flow cytometry (FCM) is a widely used technique, not only in immunology and hematology but also in many other domains and new applications have been developed in ophthalmology, for investigating ocular surface biology and pathophysiology. Apoptosis, proteins specific of cell lineage, expression of activation or immune-related markers, proinflammatory cytokine production, multi-drug resistance and oxidative stress are some examples of possible pathways that may be explored directly using ocular surface cells removed with the non-invasive technique of impression cytology, by means of flow cytometry. Conjunctival cells are thus collected by impression cytology on a filter, fixed in paraformaldehyde and dissociated by agitation before immunostaining and FCM processing. Important observations have been made concerning Sjögren's syndrome, ocular allergy and antiglaucoma eye drop toxicity. Studies performed on impression cytology with FCM techniques confirmed inflammatory and apoptotic patterns in a large number of patients with keratoconjunctivitis sicca or receiving long-term treatments with antiglaucoma drugs, even though they did not present any clinical signs of inflammation. FCM may now be used for large multicenter clinical trials and has already contributed to a better understanding of ocular surface pathophysiology, the monitoring of new immunomodulating drugs and knowledge concerning topical drugs, as regards both efficacy and safety. PMID:15106926

Brignole-Baudouin, Françoise; Ott, Ann-Christin; Warnet, Jean-Michel; Baudouin, Christophe

2004-03-01

450

Visualizing minimal ingroup and outgroup faces: Implications for impressions, attitudes, and behavior.  

PubMed

More than 40 years of research have shown that people favor members of their ingroup in their impressions, attitudes, and behaviors. Here, we propose that people also form different mental images of minimal ingroup and outgroup members, and we test the hypothesis that differences in these mental images contribute to the well-established biases that arise from minimal group categorization. In Study 1, participants were assigned to 1 of 2 groups using a classic minimal group paradigm. Next, a reverse correlation image classification procedure was used to create visual renderings of ingroup and outgroup face representations. Subsequently, a 2nd sample naive to the face generation stage rated these faces on a series of trait dimensions. The results indicated that the ingroup face was significantly more likely than the outgroup face to elicit favorable impressions (e.g., trusting, caring, intelligent, attractive). Extending this finding, Study 2 revealed that ingroup face representations elicited more favorable implicitly measured attitudes than did outgroup representations, and Study 3 showed that ingroup faces were trusted more than outgroup faces during an economic game. Finally, Study 4 demonstrated that facial physiognomy associated with trustworthiness more closely resembled the facial structure of the average ingroup than outgroup face representation. Together, these studies suggest that minimal group distinctions can elicit different mental representations, and that this visual bias is sufficient to elicit ingroup favoritism in impressions, attitudes and behaviors. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:24841095

Ratner, Kyle G; Dotsch, Ron; Wigboldus, Daniel H J; van Knippenberg, Ad; Amodio, David M

2014-06-01

451

Effect of bite tray impression technique on relocation accuracy in frameless stereotactic radiotherapy.  

PubMed

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. PMID:12747615

Herbert, Clare E; Ebert, Martin A; Barclay, D; Whittall, David S; Joseph, David J; Harper, Chris S; Spry, Nigel A

2003-01-01

452

Evaluation of Physical Properties of Tissue Conditioning Materials as used in Functional Impression - A Lab Study.  

PubMed

Background: The purpose of this study was to identify the basic physical properties of 3 commonly available tissue-conditioning materials to gain knowledge for their clinical use as impression materials. Materials & Methods: A total of 60 samples were prepared and each sample was mixed and prepared according to manufacture direction. Finally five specimens of each tissue conditioners were subjected for each of the above test at different time duration. Results & Conclusion: The study showed that all the materials underwent water loss from the time of mixing to 24 hr & became hard. The plasticity of coecomfort & viscogel decreased from the time of mixing upto 1hr & 2hr respectively & again increased after that till 24 hrs, but the softone showed decreased plasticity after 30 min till 24hrs. Softone & coecomfort at 30 min showed better flow & more plasticity than that of viscogel. The dimensional accuracy of softone & viscogel at 30min is better than that of coecomfort. Thus softone at 30 min after mixing has better Dimensional accuracy, Plasticity and Flow; suitable for making functional impression then that of Coe-comfort and Viscogel. How to cite this article: Shylesh K B S, Hallikerimath R B, Rajeev V V, Ganesh S, Meenakshi S. Evaluation of Physical Properties of Tissue Conditioning Materials as used in Functional Impression - A Lab Study. J Int Oral Health 2013; 5(3):20-27. PMID:24155598

Shylesh, Kumar B S; Hallikerimath, R B; Rajeev, V V; Ganesh, S; Meenakshi, S

2013-06-01

453

Evaluation of Physical Properties of Tissue Conditioning Materials as used in Functional Impression - A Lab Study  

PubMed Central

Background: The purpose of this study was to identify the basic physical properties of 3 commonly available tissue-conditioning materials to gain knowledge for their clinical use as impression materials. Materials & Methods: A total of 60 samples were prepared and each sample was mixed and prepared according to manufacture direction. Finally five specimens of each tissue conditioners were subjected for each of the above test at different time duration. Results & Conclusion: The study showed that all the materials underwent water loss from the time of mixing to 24 hr & became hard. The plasticity of coecomfort & viscogel decreased from the time of mixing upto 1hr & 2hr respectively & again increased after that till 24 hrs, but the softone showed decreased plasticity after 30 min till 24hrs. Softone & coecomfort at 30 min showed better flow & more plasticity than that of viscogel. The dimensional accuracy of softone & viscogel at 30min is better than that of coecomfort. Thus softone at 30 min after mixing has better Dimensional accuracy, Plasticity and Flow; suitable for making functional impression then that of Coe-comfort and Viscogel. How to cite this article: Shylesh K B S, Hallikerimath R B, Rajeev V V, Ganesh S, Meenakshi S. Evaluation of Physical Properties of Tissue Conditioning Materials as used in Functional Impression - A Lab Study. J Int Oral Health 2013; 5(3):20-27.

Shylesh, Kumar B S; Hallikerimath, R B; Rajeev, V V; Ganesh, S; Meenakshi, S

2013-01-01

454

Permeation of gases through composite membranes prepared by radio-frequency and microwave plasma polymerization of siloxanes  

NASA Astrophysics Data System (ADS)

In this work, the permeation of gases and condensible vapors through composite membranes was studied. Helium, hydrogen, argon, oxygen, nitrogen, methane, carbon dioxide, ethylene, acetylene, sulfur dioxide, propane, n-butane and sulfur hexafluoride were used as permeant gases. Composite membranes were prepared by the deposition of either radio-frequency or microwave plasma polymerized siloxanes onto polymer substrates of porous Celgard. The starting monomer was either hexamethy1disiloxane (HMDSO) or octamethyl-cyclotetrasiloxane (OMCTSO). The films were characterized by FTIR, ESCA, TGA, density and contact angle measurements. The permeabilities of the of the microwave and radio-frequency plasma polymerized siloxane membranes for thirteen gases were measured and compared. The permeabilities were similar to those for conventional PDMS. Temperature and pressure dependence of permeability was measured. From the temperature dependence of permeability, activation energies for permeation were calculated. These were positive except for permeation of butane in RF PPHMDSO, which was negative. The activation energies were lower than for conventional PDMS. The permeabilities did not strongly depend on pressure up to 42 psia. It was observed that permeabilities for gases showed dependence on molecular size, but the correlation was not as strong as for plasma polymerized fluorocarbon membranes. As molecular size increased from 2.58 A (helium) to 5.6 A (sulfur hexafluoride), the permeabilities of the membranes exhibited a decreasing trend. Within a group of permeant gases of similar size, e.g. argon, oxygen and nitrogen, or methane and carbon dioxide, the permeabilities increased with critical temperature. It was also observed that the solubility parameter, delta, correlated with the permeability for gases having similar molecular size. The density of the films increased in the order: RF PPHMDSO < microwave PP HMDSO < microwave PP OMCTSO. Permeabilities decreased, and O2/N 2 selectivity increased, as the density of the plasma polymer films increased. Permeation of butane through RF PPHMDSO showed unusual behavior. The permeation activation energy was negative. Butane permeation reduced the permeability of the membrane to nitrogen by 15%. After a 24 hour period the permeability returned to normal.

Lal, Akhil

455

Antibacterial efficacy and effect of chlorhexidine mixed with irreversible hydrocolloid for dental impressions: a randomized controlled trial.  

PubMed

This study aimed to evaluate whether chlorhexidine mixed with irreversible hydrocolloid powder decreases microbial contamination during impression taking without affecting the resulting casts. Twenty volunteers were randomly divided into two groups (n = 10) according to the liquid used for impression taking in conjunction with irreversible hydrocolloid: 0.12% chlorhexidine or water. Surface roughness and dimensional stability of the casts were evaluated. Chlorhexidine mixed with irreversible hydrocolloid decreased the percentage of microorganisms when compared with water (P < .001) but did not affect the surface quality or dimensional stability of the casts. Mixing chlorhexidine with irreversible hydrocolloid powder is an alternative method to prevent contamination without sacrificing impression quality. PMID:25010881

Cubas, Glória; Valentini, Fernanda; Camacho, Guilherme Brião; Leite, Fábio; Cenci, Maximiliano Sérgio; Pereira-Cenci, Tatiana

2014-01-01

456

DIAGNOdent measurements and correlation with the depth and volume of minimally invasive cavity preparations.  

PubMed

In this clinical study, DIAGNOdent (KaVo) was used to assess previously diagnosed carious lesions in the pits and fissures of first and second molars. The measurements from this device were correlated with the depth and volume of the cavity preparations that resulted from minimal intervention to remove occlusal carious lesions. Twenty-five patients, 18 years of age and older, who were previously scheduled for an occlusal restoration due to caries, were recruited and enrolled in this clinical study. These patients had 48 qualifying teeth without previous restorations, sealants or other carious lesions. The occlusal surface of each study tooth was cleaned utilizing ProphyFlex2 (KaVo). Two dentists separately traced the pit and fissure system of each tooth using DIAGNOdent for two 15-second periods each. The peak reading of each of the four measurements was recorded. An impression of the occlusal surface of each tooth was recorded with a polyvinyl siloxane bite registration material. The carious lesions were removed with an air abrasion unit employing a 0.015-inch nozzle opening utilizing minimal operative intervention. A low viscosity polyvinyl siloxane was used to take an impression of the cavity preparation impression, using the bite registration impression to form the occlusal surface of the preparation impression. The preparation impression volume was calculated from its weight, using the known density of the impression material. The greatest depth of the preparation was measured. The Pearson correlation coefficient was used to investigate any relationship between depth or volume of the preparation impression and the DIAGNOdent measurements. The correlation for preparation volume and maximum DIAGNOdent measurement was 0.191 (p = 0.189). Other logical subsets of cases also did not result in any statistically significant correlations between the DIAGNOdent readings and the depth or volume of the final cavity preparations. PMID:16802636

Hamilton, James C; Gregory, William A; Valentine, John B

2006-01-01

457

Making a Positive Impression about the Mission of an Urban, Catholic University: Gender, First-Generation College, and Religious Preference Comparisons  

ERIC Educational Resources Information Center

This study investigates how research participants' desire to make a positive social impression may affect their responses to survey questions. Specifically, participants may react in socially appropriate ways to create a positive social impression for those persons reviewing their responses. This concept is termed "impression management," or more…

Ferrari, Joseph R.; Mader, Megan C.; Milner, Lauren A.; Temperato, John R.

2010-01-01

458

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

NASA Astrophysics Data System (ADS)

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°.

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

2007-02-01

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