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1

Effect of provisional luting agents on polyvinyl siloxane impression material  

Microsoft Academic Search

Eugenol-containing cements have been traditionally selected for seating provisional restorations, but incomplete polymerization of polyvinyl siloxane impression materials has been attributed to these cements. This study clinically evaluated the inhibitory effect on polymerization of a specific polyvinyl siloxane impression material with five luting agents used for provisional restorations. Three of these luting agents contained eugenol, whereas two interim cements did

Rodney H Jones; Gregory S Cook; Marty G Moon

1996-01-01

2

Accuracy of three polyvinyl siloxane putty-wash impression techniques  

Microsoft Academic Search

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

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

2000-01-01

3

Effect of non-ionic surfactants on surface properties of hydrophilic polyvinyl siloxane impression materials  

Microsoft Academic Search

This study examines the effect of non-ionic surfactants on surface hydrophilicity and detail reproducibility of die stone for hydrophilic polyvinyl siloxane impression materials. Hydrophilic polyvinyl siloxane impression materials were prepared with a polydimethylsiloxane composition and non-ionic surfactants. The surfactants used were nonylphenoxy poly(ethyleneoxy) ethanol homologs of varying ethyleneoxy chain length. These homologs are designated NP4, NP6, and NP10 according to

Young-Il Oh; Doug-Youn Lee; Soo-Young Hwang; Kyoung-Nam Kim; Kwang-Mahn Kim

2003-01-01

4

The effect of temperature changes on the dimensional stability of polyvinyl siloxane and polyether impression materials  

Microsoft Academic Search

Statement of problem. Dental impressions are commonly mailed to remote dental laboratories and can be subjected to extreme temperature changes; however, the effects of these temperature changes on the accuracy of elastomeric impression materials are unknown.Purpose. This study evaluated the dimensional changes of polyether and polyvinyl siloxane impression materials as a function of storage temperature.Material and methods. A total of

Marco Corso; Abdulhadi Abanomy; James Di Canzio; David Zurakowski; Steven M. Morgano

1998-01-01

5

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

PubMed

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

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

2013-12-01

6

Effect of frequency and amplitude of vibration on void formation in dies poured from polyvinyl siloxane impressions  

Microsoft Academic Search

Statement of problem. Numerous factors are involved in making a void-free dental stone cast from a polyvinyl siloxane impression.Purpose. The aim of this study was to determine whether frequency and amplitude of vibration had any effect on the formation of voids on the cast surface poured from polyvinyl siloxane impression with a mechanical model vibrator.Material and methods. Impressions were poured

Mohammed Aleem Abdullah

1998-01-01

7

The effect of various base\\/core materials on the setting of a polyvinyl siloxane impression material  

Microsoft Academic Search

Five resin-modified glass ionomers and amalgam, used as a base or core buildup material, were clinically evaluated for whether they effected polymerization of a low viscosity (light body) regular set polyvinyl siloxane impression material. A total of 20 samples per group was prepared according to the manufacturer's recommendations. Ten samples from each group were handled with latex gloves during mixing

Marty G Moon; Thomas A Jarrett; Rickey A Morlen; Glen J Fallo

1996-01-01

8

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. PMID:24324310

Dugal, Ramandeep; Railkar, Bhargavi; Musani, Smita

2013-01-01

9

Dimensional stability of polyvinyl siloxane impression material reproducing the sulcular area.  

PubMed

The dimensional stability of a thin intra sulcular impression material reproducing the preparation finish line was evaluated. Impressions were taken of a stainless-steel master model of a simulated abutment with a 'gingival sulcus' using Express regular, Express fast and Aquasil. The putty-wash two-step technique was applied with spacer thicknesses of 0.5, 1 and 1.5 mm. Mid mesiodistal and bucco-lingual measurements were taken directly from the sulcular impression material after 0.5, 2, 24, 48 and 72 h via a Toolmaker's microscope. The discrepancies between the measurements of the impression material and the master model were calculated. The discrepancies changed significantly over time (p<0.001). The use of a 0.5 mm spacer resulted in a negative deviation from the model (2-46 µm), minimally after 2 h. The use of 1 and 1.5 mm spacers showed a positive deviation from the model (21-52 µm) and both are equally recommended. Investment can be postponed until 72 h. PMID:23370867

Levartovsky, Shifra; Levy, Guy; Brosh, Tamar; Harel, Noga; Ganor, Yehuda; Pilo, Raphael

2013-01-01

10

Effect of Surfactant Treatment on the Surface Roughness of Stone Casts produced from Potyvinyle Siloxane Impression  

Microsoft Academic Search

The surface raughness oJ' stone tasts protluced .from hj'drophilic poly,inyl siloxane impre,ssion material was compared wilh hydrophohic polyvinyl .siloxane impression either treated or not treated with topical surfhctant. There was no significant diflerence in snrJace roughness of ca,sts produced from hydrophilic polyvinyl siloxane impressions compared with casts obtained Jiont hyslropfio6lc polyinyl .siloxane impressions treated with topical surlsclant. However, Ihere was

Alaa M. EI-Arahy

11

Effect of frequency and amplitude of vibration and role of a surfactant on void formation in models poured from polyvinyl siloxane impressions  

PubMed Central

Aims: To determine whether the frequency and amplitude of vibration and the use of surfactant has any effect on the formation of voids on the cast surface, poured from a polyvinyl siloxane impression material, using a mechanical model vibrator. Materials and Methods: A total of 100 impressions of a master die were made using Reprosil, Type 1, Medium Viscosity, Regular body, and Dentsply Caulk. The test group was subdivided into a surfactant and non-surfactant group, 50 impressions each. The impressions were poured in a dental stone with a mechanical model vibrator that was set at a vibration frequency of 3000 cycles / minute (low) and 6000 cycles / minute (high) with the help of a knob. The resultant casts were examined with a Stereomicroscope (LABOMED CZM4) under ×10 magnifications. Results: For the low and high frequencies, when surfactant and non-surfactant groups were compared, for all the amplitudes and for both the material groups, the surfactant groups resulted in fewer void formations and showed very high statistical significance (P-value = 0.001). Conclusions: The lowest mean voids were obtained for high frequency surfactant groups. Reprosil: High frequency amplitude 2 being the most prominent, produced the least mean voids (mean = 23.2000, P = 0.001, very highly significant). In comparison, the surfactant groups produced the least voids for both frequencies. PMID:21814356

Reddy, N Kulashekar; Aparna, IN

2011-01-01

12

Effect of five brands of latex gloves on the setting time of polyvinyl siloxane putty impression materials.  

PubMed

Addition silicone impression materials have been used as impression material for more than 20 years. Although they are among the most expensive impression materials, they became popular during the past decade as they have excellent physical properties. Prevention of infection is an important aspect in dental treatment since dental professionals are routinely exposed to the wide variety of microorganisms present in saliva. Gloves are the most common protective measure used during dental treatment. The gloves are mostly made of latex. In this study, we examine how the setting time of three types polyvinyl putty materials were affected by the use of five different brands of latex gloves and one brand of vinyl gloves. Each material was first mixed without wearing gloves according to the manufacturer's instructions. After the stipulated mixing time, the setting time was measured using the Vicat needle. The setting time is measured from the time of mixing till the time that the needle does not produce any indentation on the surface of the material. The putty material was then mixed with gloved hands (using the five different brands of latex gloves in turn) and the setting time was measured. Then the material was mixed with washed gloved hands, and the setting time was measured again. Finally, the material was mixed with vinyl gloved hands and the setting time was measured. The following conclusions were drawn from the study: Reprosil and Express showed significant variation in the setting time with the latex gloved hands.There was no significant variation in the setting time when material was mixed with unwashed vs washed gloved hands.Vinyl gloves did not significantly affect the setting time of any of the putty impression materials. PMID:22945711

Ravikumar, C M; Sangur, Rajashekar

2012-01-01

13

Compressibility of two polyvinyl siloxane interocclusal record materials and its effect on mounted cast relationships  

Microsoft Academic Search

Statement of problem. Addition silicones (polyvinyl siloxanes) are universally accepted as accurate and stable impression materials. They have also gained popularity as interocclusal record materials. However, it has not been defined if it is possible to work with polyvinyl siloxanes without changing the recorded maxillomandibular relations. Purpose. This study examined the compressibility of 2 addition silicones as interocclusal record materials,

Adeliani Almeida Campos; Dan Nathanson

1999-01-01

14

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

PubMed Central

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

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

2014-01-01

15

The effect of marginal thickness on the distortion of different impression materials  

Microsoft Academic Search

An impression of the margins of a prepared tooth and adjacent gingival sulcus must be of sufficient thickness to withstand distortion and tearing when the impression is removed from the mouth. The purpose of this study was to compare the dimensional accuracy of Elite, Examix, and Express polyvinyl siloxanes; Permadyne polyether; and Permlastic polysulfide elastomeric impression materials. These materials were

Ben-Zion Laufer; Haim Baharav; Yehuda Ganor; Harold S Cardash

1996-01-01

16

Effects of chemical disinfectant solutions on the stability and accuracy of the dental impression complex  

Microsoft Academic Search

Currently available impression materials were not designed for disinfection or sterilization, and it is conceivable that disinfectants may adversely affect impressions. This study evaluated the accuracy and dimensional stability of polyether (Permadyne\\/Impregum) and polyvinyl siloxane (Express) impression materials retained by their adhesives in two different acrylic resin tray designs (perforated and nonperforated) when the materials were immersed for either 30

Maria del Pilar Rios; Steven M Morgano; R. Sheldon Stein; Lynda Rose

1996-01-01

17

Visualization and measurement of nanometer dimension surface features using dental impression materials and atomic force microscopy  

Microsoft Academic Search

The resolving ability of polyvinyl siloxane impression material at a submicron scale was tested in order to determine its ability to reproduce the topographical features of worn contact surfaces such as those found in the food processing industry. Three impression materials were tested against three surfaces with standardized surface features. Cryo scanning electron microscopy and atomic force microscopy were used

Joanna Verran; Deborah L. Rowe; Robert D. Boyd

2003-01-01

18

Blockout technique for impressions of teeth with increased open gingival embrasures  

Microsoft Academic Search

A dental technique is described that blocks out enlarged gingival embrasures to eliminate distortion of an impression and the resultant cast for removable partial or fixed partial dentures. This procedure consists of injecting polyvinyl siloxane impression material in embrasures to form custom blockout wedges. This technique provides a simple method for clean, customized blockout of potentially damaging undercuts that can

Thomas W. Hummert; David A. Kaiser

1999-01-01

19

Effects of implant angulation, material selection, and impression technique on impression accuracy: a preliminary laboratory study.  

PubMed

The aim of this preliminary laboratory study was to evaluate the effects of 5- and 25-degree implant angulations in simulated clinical casts on an impression's accuracy when using different impression materials and tray selections. A convenience sample of each implant angulation group was selected for both open and closed trays in combination with one polyether and two polyvinyl siloxane impression materials. The influence of material and technique appeared to be significant for both 5- and 25-degree angulations (P < .05), and increased angulation tended to decrease impression accuracy. The open-tray technique was more accurate with highly nonaxially oriented implants for the small sample size investigated. PMID:22930776

Rutkunas, Vygandas; Sveikata, Kestutis; Savickas, Raimondas

2012-01-01

20

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

21

Evaluation of dimensional stability of autoclavable elastomeric impression material.  

PubMed

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

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

2011-03-01

22

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

23

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

PubMed

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

Ozcelik, Tuncer Burak; Yilmaz, Burak

2012-01-01

24

A comparison of impression materials for complete-arch fixed partial dentures.  

PubMed

This study compared the marginal fit of complete-arch fixed prostheses under simulated clinical conditions. Prostheses were made on casts constructed from three commonly used impression materials; polyether, polyvinyl siloxane (medium-viscosity and putty-wash), and reversible hydrocolloid. A maxillary dentoform with four abutment teeth was used as the master cast and six impressions were made with each material. Individual castings for each abutment were made on the stone casts. The abutment castings were luted together on the casts to provide a complete-arch fixed partial denture using a ticonium framework and acrylic resin. The marginal fit of the abutment castings was measured on the master cast before and after the prostheses were luted together. The polyether and both addition silicone impression materials were significantly more accurate than the reversible hydrocolloid in both situations. All of the single castings were clinically acceptable, but the luted restorations made from reversible hydrocolloids were not. PMID:2051350

Dounis, G S; Ziebert, G J; Dounis, K S

1991-02-01

25

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

26

Effect of Splinting in Accuracy of Two Implant Impression Techniques.  

PubMed

Abstract Purpose: Because there is no consensus in the literature about the need for a splint between copings, the aim of this study was to evaluate, in vitro, the accuracy of two impression techniques for implant-supported prostheses. Methods: A master cast was fabricated with four parallel implant abutment analogs and a passive framework. Two groups with five casts each were formed: Group 1 (squared impression copings with no splint - S) and Group 2 (splinted squared impression copings, using metal drill burs and Pattern resin - SS). The impression material used was polyvinyl siloxane with open trays, for standard preparation of the casts. For each cast, the framework was positioned, and a titanium screw was tightened with 10 N*cm torque in analog A, after which measurements of the abutment-framework interface gaps were performed at analogs C and D. This process was repeated for analog D. These measurements were analyzed using software (Leica QWin, Leica Imaging Systems). A one-way analysis of variance (ANOVA) with a confidence interval of 95% was used to analyze the data. Results: Significant differences were detected between S and SS in relation to the master cast (P ? 0,05). The median values of the abutment/framework interface gaps were as follows: master cast: 39,64?m; squared impression copings with no splint: 205, 86?m; splinted squared impression copings: 99,19?m. Conclusion: Under the limitations of this study, the technique presented for Group 2 produces better results compared with the technique used for group 1. PMID:23101476

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

2012-10-26

27

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

28

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

29

Siloxane-modified polyethersulfideimide  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

30

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

31

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

32

Impressions count.  

PubMed

Nursing has long been preoccupied with its own image (Kalish & Kalish, 1987). However, the professional image of license practical/vocational nurses is vitally significant because it influences not only how you feel about yourself, but how others including physicians, other professionals, and patients relate to you and how much responsibility and empowerment you have. Your power to speak as a patient advocate and to influence policy decisions is intricately related to your image as work and in the community. Professional image is complex and is the result of impressions made by appearance, written communication, attitudes and behaviors, and time management. Frequently, the impressions you make in the first twelve seconds of meeting an individual is the one they will retain about you. Since ultimately, the image the public has of your profession begins with you attention to professional image involves a 365 day a year commitment (Stille, 1992). PMID:9687663

Davidhizar, R

1998-06-01

33

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

34

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

35

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

36

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

37

Polyimides containing pendent siloxane groups  

NASA Technical Reports Server (NTRS)

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

Connell, John W.

1991-01-01

38

40 CFR 721.9515 - Aminofunctional alkoxy alkyl siloxane.  

Code of Federal Regulations, 2010 CFR

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

2010-07-01

39

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.

40

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

41

First Impressions and Expectancies  

Microsoft Academic Search

It was hypothesized that (a) impressions of a stranger as bad and potent would result in greater expectation of harm and less expectation of benefits than good and impotent impressions, and (b) disconfirmation of these expectations would result in changes in level of expressed attractiveness. Forty female introductory psychology students participated in an initial investigation, and 20 male introductory psychology

Robert C. Brown Jr; R. Bob Smith III; James T. Tedeschi

1975-01-01

42

ETI: Our first impressions  

NASA Astrophysics Data System (ADS)

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

Harrison, Albert A.; Johnson, Joel T.

2000-06-01

43

Photoluminescence characteristics of phenylated siloxanes  

NASA Astrophysics Data System (ADS)

The unique interaction between conjugated ? -electron systems and the Si atom in phenyl-substituted silanes and siloxanes gives rise to chromophore behavior of these substances. Phenylsilanes and phenylsiloxanediols as well as variously substituted cyclotrisiloxanes and cyclotetrasiloxanes were synthesized, and complete excitation-emission maps were obtained in the ultraviolet-to-visible spectral range. The position of the emission maxima was analyzed from intensity contour plots. Two different types of behavior were identified for compounds such as the cyclosiloxanes: with hexaphenylcyclotrisiloxane, the position of the main emission maximum at 357 nm did not depend on the excitation wavelength, while for octaphenylcyclotetrasiloxane the spectral position of the maximum increased with the excitation wavelength. A model for this phenomenon and evidence for the effects of methyl vs phenyl substituents will be discussed.

Pernisz, Udo C.; Backer, Michael W.

2001-03-01

44

Polyimides That Contain Pendent Siloxane Groups  

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

45

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

46

Comparison of impression materials for direct multi-implant impressions  

Microsoft Academic Search

Statement of problem. Given that meticulous implant prosthodontic procedures are recommended to obtain the best possible intraoral fit, impression materials that are suitable for use with a direct impression technique warrant further investigation. Purpose. This in vitro study compared the amount of torque required to rotate a square impression coping in an impression and evaluated the accuracy of solid implant

Alvin G. Wee

2000-01-01

47

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

48

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

49

Impression techniques for implant dentistry  

Microsoft Academic Search

The object of making an impression in implant dentistry is to accurately relate an analogue of the implant or implant abutment to the other structures in the dental arch. This is affected by use of an impression coping which is attached to the implant or implant abutment. This impression coping is incorporated in an impression – much as a metal

S Jivraj; W Chee

2006-01-01

50

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

51

Impressions of Leadership  

ERIC Educational Resources Information Center

I was early arriving for an appointment with the superintendent at the school where I would begin my first year as an elementary school principal. While I waited, I reflected on my first teaching job, where I had formed my first and most lasting impressions of leadership from the principal. Now it was my turn to be a principal, and I aspired to…

Smith, Agnes

2005-01-01

52

Get ready to impress.  

PubMed

More than 40 trusts, charities, agencies and companies will be looking for the brightest recruits at the RCN Bulletin jobs fair in Leeds next month. Here are some top tips to ensure you make the right impression and give a winning performance to potential employers on the day. PMID:25370270

Cole, Elaine

2014-11-01

53

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

54

SOURCE ASSESSMENT: POLYVINYL CHLORIDE  

EPA Science Inventory

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

55

Some impressions of the department  

E-print Network

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

Sorkin, Michael David

1984-01-01

56

Tool for Taking Clay Impressions  

NASA Technical Reports Server (NTRS)

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

Duncan, R. S.

1984-01-01

57

Vibrational spectroscopy of the ring structures in silicates and siloxanes  

NASA Astrophysics Data System (ADS)

In the presented paper an attempt to build a structural model for crystal silicates on the basis of selected siloxane systems has been proposed. Siloxanes and silicates are different chemical compounds arranged as molecular or ionic crystals, respectively. Siloxane group (Si-O bond) is their common feature. It is suggested that as the proportion of the Si-O to Si-C bonds in the siloxane structure grows they become more similar to silicates. In the investigations siloxanes with -CH 3 as a terminal group and selected silicates have been chosen as model compounds. Vibrational spectroscopy has been used as an investigation tool. For the selected siloxane molecules infrared spectra have been calculated (HF/6-31G(d) method) and compared with the experimental ones of siloxanes and silicates. It has been found that the spectra corresponding to siloxanes and silicates of similar structures agree fairly well in spite of different character of alkyl group present in siloxanes from that of metal cations in silicates. Based on the spectra similarities visual analysis of siloxanes normal vibrations has been applied to identify the bands in the spectra of silicates. Accuracy of such band identification in the spectra of silicates grows with the increase in the SiO 4 tetrahedra connectedeness. It becomes possible from structures composed of secondary tetrahedra (Q2) but similarities are significant starting from the structures with tertiary (Q3) tetrahedra which makes it possible to distinguish them as a separate group of molecular silicates.

Handke, Miros?aw; Jastrz?bski, Witold

2004-10-01

58

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

59

Siloxane treatment by adsorption into porous materials.  

PubMed

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

Ricaurte Ortega, D; Subrenat, A

2009-09-01

60

Drug and dental impression materials  

PubMed Central

Guidelines to prevent cross contamination with infectious agents have been instituted for dental clinical and laboratory procedures. However, compliance by dental offices and clinics in disinfecting impression material has not been universal. Techniques for disinfecting impression materials are spraying or immersing impression materials. These techniques can reduce the surface detail and dimensional accuracy of impressions; most disinfectants are irritants. This study reviewed whether antimicrobial activity can be achieved by mixing certain drugs with the impression material and their effects on the disinfection are achieved through such additions. PMID:23066280

Maller, Sudhakara V.; Karthik, K. S.; Maller, Udita S.; Abraham, Mathew C.; Kumar, Rachuri Narendra; Manikandan, R.

2012-01-01

61

Dental impression materials.  

PubMed

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

Perry, Rachel

2013-01-01

62

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

Code of Federal Regulations, 2010 CFR

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

2010-07-01

63

Ultrahigh Molecular Weight Aromatic Siloxane Polymers  

NASA Technical Reports Server (NTRS)

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

Ludwick, L. M.

1983-01-01

64

Synthesis of Glucose-Modified Siloxanes by a Simplified Procedure  

Microsoft Academic Search

A simplified alternative for the synthesis of carbohydrate-modified siloxanes is described. The starting siloxane precursors contain glycidyl functional groups, which are reacted with glucose in dimethylformamide (DMF), in the presence of a gel type cation exchanger. The method eliminates protection-deprotection reactions, as well as moisture-sensitive or multiple reaction steps. Glycidyl-functionalized siloxane compounds are commercially available, but can be easily obtained

Carmen Racles; Vasile Cozan

2011-01-01

65

Synthesis of Glucose-Modified Siloxanes by a Simplified Procedure  

Microsoft Academic Search

A simplified alternative for the synthesis of carbohydrate-modified siloxanes is described. The starting siloxane precursors contain glycidyl functional groups, which react with glucose in dimethylformamide (DMF), in the presence of a gel type cation exchanger. The method eliminates protection-deprotection reactions, as well as moisture-sensitive or multiple reaction steps. Glycidyl-functionalized siloxane compounds are commercially available, but can be easily obtained in

Carmen Racles; Vasile Cozan

2012-01-01

66

Siloxane modified cycloaliphatic epoxide UV coatings  

Microsoft Academic Search

Tetraethyl orthosilicate (TEOS) functionalized caprolactone diol and triol were used to modify cycloaliphatic diepoxide\\/caprolactone polyol cationic ultraviolet (UV) curable coatings. Two levels of the cycloaliphatic diepoxide (60 and 70wt.%) were used in the coating formulations. Siloxane functionalized polyols were added to the cycloaliphatic diepoxide\\/caprolactone polyol coating formulations as a replacement of the parent caprolactone polyols. To monitor the potlife, the

Shaobing Wu; Matthew T. Sears; Mark D. Soucek

1999-01-01

67

Relevance of an organic solvent for absorption of siloxanes.  

PubMed

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

Ghorbel, Leila; Tatin, Romuald; Couvert, Annabelle

2014-01-01

68

Implant overdenture impressions using a dynamic impression concept  

PubMed Central

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

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

2014-01-01

69

Surface microtopography in siloxane–polyurethane thermosets: The influence of siloxane and extent of reaction  

Microsoft Academic Search

The effect of polydimethylsiloxane (PDMS) content, PDMS molecular weight, and the extent of prepolymerization reactions between hydroxyl functional PDMS and polyisocyanate were explored in order to understand the influence of these variables on the formation of surface microtopography in a siloxane–polyurethane thermoset. The system is based on a difunctional hydroxyalkyl terminated PDMS, trifunctional poly(caprolactone) polyol, and a polyisocyanate. The effect

Partha Majumdar; Dean C. Webster

2007-01-01

70

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

71

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

72

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

NASA Astrophysics Data System (ADS)

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

Cole, Megan A.

73

Kinetic investigation of the solvation of lithium salts in siloxanes.  

SciTech Connect

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

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

2008-02-14

74

Method and apparatus for siloxane measurements in a biogas  

US Patent & Trademark Office Database

A method for monitoring of siloxane compounds in a biogas includes the step of generating a first absorption spectrum based on a ratio of a first spectral measurement and a second spectral measurement. The first spectral measurement is from a non-absorptive gas having substantially no infrared absorptions in a specified wavelength range of interest and the second spectral measurement is from a sample gas comprising the biogas. The method also includes the step of calculating a concentration of at least one siloxane compound in the biogas using a second absorption spectrum based on, at least, a first individual absorption spectrum for a known concentration of the at least one siloxane compound.

2013-06-11

75

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

76

Structure property behavior of polyimide siloxane segmented copolymers  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

77

New siloxane–ester modified polysulfones by phase transfer catalysis  

Microsoft Academic Search

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

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

2000-01-01

78

75 FR 61175 - Polyvinyl Alcohol From Taiwan  

Federal Register 2010, 2011, 2012, 2013

...731-TA-1088 (Final)] Polyvinyl Alcohol From Taiwan AGENCY: United States International...less-than-fair-value imports from Taiwan of polyvinyl alcohol, provided for in subheading 3905.30...of Commerce that imports of polyvinyl alcohol from Taiwan are being sold in the...

2010-10-04

79

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

80

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

PubMed

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

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

2010-08-15

81

Effect of siloxane functionalized caprolactone polyols on photocurable epoxy coatings  

Microsoft Academic Search

Cationic ultraviolet (UV) coatings were formulated using a cycloaliphatic diepoxide (3,4-epoxycyclohexyl methyl-3?, 4-?epoxycyclohexane\\u000a carboxylate) with siloxane modified caprolactone polyols. Both di- and tri-TEOS (tetraethyl orthosilicate) functionalized\\u000a caprolactone polyols were used to modify the UV coatings. The resulting coatings were cured and evaluated in terms of pencil\\u000a hardness, MEK double rubs, crosshatch\\/pull-off adhesion, and reverse impact resistance. Addition of the siloxane-functionalized

Shaobing Wu; Mark D. Soucek

1998-01-01

82

Synthesis and photopolymerization of propenyl ether and epoxy functionalized siloxanes  

NASA Astrophysics Data System (ADS)

The reactive precursors, 1-allyloxy-4(1-propenoxy)butane and allyl-epoxy-ester, were synthesized. The synthesis of propenyl ether and epoxy functionalized siloxanes has been achieved by the controlled, rhodium-catalyzed, chemoselective hydrosilation of allyl ether with various H-functional siloxanes. It was shown that the hydrosilation proceeds exclusively at the allyl ether group of allyloxy-propenoxybutane without participation at the propenyl ether group. The photoinduced cationic polymerization of these monomers was studied and found to be all highly reactive.

Kim, W. G.; Ahn, H. K.; Lee, H. W.; Kim, S. H.; Crivello, J. V.

2003-01-01

83

Stretching siloxanes: An ab initio molecular dynamics study  

NASA Astrophysics Data System (ADS)

We present an ab initio molecular dynamics study of siloxane elastomers placed under tensile stress for comparison with single molecule AFM experiments. Of particular interest is stress-induced chemical bond breaking in the high force regime, where a description of the molecular electronic structure is essential to determine the rupture mechanism. We predict an ionic mechanism for the bond breaking process with a rupture force of 4.4 nN for an isolated siloxane decamer pulled at a rate of 27.3 m/s and indicate lower values at experimental polymer lengths and pulling rates.

Lupton, E. M.; Nonnenberg, C.; Frank, I.; Achenbach, F.; Weis, J.; Bräuchle, C.

2005-10-01

84

The Influence of Diphenyl Siloxane on Morphology and Physical Properties in the Poly(Imide Siloxane)(PIS) Copolymer  

Microsoft Academic Search

Various numbers of diphenyl-siloxane groups were incorporated in ?,?-bis(aminopropyl)polydimethylsiloxane (APPS) to prepare\\u000a ?,?-bis(aminopropyl)-polydimethyldiphenylsiloxane (APPPS) oligomers of three different number-average molecular weights(Mn\\u000a = 547,772,1210 g mol?1).These APPPS oligomers were than used, together with 3,3?,4,4?-bezonphenone tetracarboxylic dianhydride (BTDA) and 2-2?-bis[4-(3-aminophenoxy)phenyl]\\u000a sulfone (m-BAPS), to synthesize a series of APPPS containing poly(imide siloxane) (PIS) copolymers. Microstructural studies\\u000a showed that at certain APPPS content, a critical

Wen-Chang Liaw; Kuan-Pin Chen

2007-01-01

85

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

86

Preparation and characterization of siloxane-containing thermoplastic polyimides  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

87

Safe human exposure limits for airborne linear siloxanes during spaceflight  

PubMed Central

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

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

2013-01-01

88

From hydrophobic to superhydrophobic and superhydrophilic siloxanes by thermal treatment.  

PubMed

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

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

2014-11-11

89

21 CFR 177.1670 - Polyvinyl alcohol film.  

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

2014-04-01

90

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

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Siloxanes and silicones, Me hydrogen, reaction products with 2,2...721.6170 Siloxanes and silicones, Me hydrogen, reaction products with 2,2...identified as siloxanes and silicones, Me hydrogen, reaction products with...

2010-07-01

91

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

92

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

93

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

94

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

95

Altering First Impressions After Facial Plastic Surgery  

Microsoft Academic Search

Background First impressions are greatly influenced by facial appearance. Clinical data from psychiatric medicine overwhelming indicate that attractive individuals receive better judgment, treatment and behavior [1,2,10]. This study aimed to determine whether cosmetic alteration of facial features projects a better first impression. Methods Random reviewers were asked independently to grade standardized preoperative and postoperative photographs of patients who underwent facial

Steven Dayan; Kirk Clark; Allan A. Ho

2004-01-01

96

Sport Fans' Impressions of Gay Male Athletes  

Microsoft Academic Search

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

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

2011-01-01

97

Sodium hyaluronate and polyvinyl alcohol artificial tear preparations. A comparison in patients with keratoconjunctivitis sicca.  

PubMed

An unpreserved artificial tear substitute containing 0.1% sodium hyaluronate was compared with a preparation containing 1.4% polyvinyl alcohol and 0.5% chlorobutanol in a controlled, double-masked, randomized study in patients with moderately severe keratoconjunctivitis sicca. Patients were evaluated initially, at 1, 4, and 8 weeks. The dry-eye status was evaluated by means of tear-film osmolality, tear breakup time, rose bengal staining, Schirmer's test (without anesthesia), and ocular surface-impression cytology. In general, neither preparation was found to be superior to the other. In both study groups, the mean tear-film osmolality and rose bengal staining score improved over the eight-week study, but the degree of squamous metaplasia of the bulbar conjunctival surface, as shown by impression cytology, did not change significantly. PMID:2451494

Nelson, J D; Farris, R L

1988-04-01

98

Two-dimensional solid state NMR characterization of physisorbed siloxane polymer (OV-225) on silica  

Microsoft Academic Search

Physisorbed cyanopropyl methyl phenyl methyl siloxane polymer on a silica surface was characterized by one- and two-dimensional solid state NMR techniques including heteronuclear proton silicon correlation spectroscopy. Spin lattice relaxations of protons of the siloxane polymer exhibited only small changes upon anchoring to the silica surface indicating somewhat altered molecular dynamics of proton moieties that contribute to the relaxation process.

Anima B. Bose; Mahinda Gangoda; Mietek Jaroniec; Roger K. Gilpin; Rathindra N. Bose

2006-01-01

99

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

100

Vibrational spectroscopy of the double 4-, 6-membered rings in silicates and siloxanes  

NASA Astrophysics Data System (ADS)

Siloxanes and silicates are different chemical compounds but they all contain silicooxygen units. Double 6-membered silicooxygen rings are important building units of more complicated silicate structures (silicalites and zeolites). The aim of this work is to understand vibrational spectra of double 6-membered cyclosilicates based on the spectra of selected siloxanes. For the selected siloxane molecules infrared spectra have been calculated (using various terminal groups) by ab initio method and compared with the experimental ones of silicates. Visualization of the calculated normal modes has been used as a tool to define the band type in the spectra of siloxanes and to interpret them in terms of group-characteristic frequencies as tetrahedral, overtetrahedral and ring bands. Similarities between IR spectra of T8 and T12 siloxanes and the spectra of double 4-, 6-membered cyclosilicates allow to identify the bands in the experimental spectra of silicates.

Handke, Miros?aw; Jastrz?bski, Witold

2005-06-01

101

Going To Work: Make a Good Impression  

E-print Network

Edited by Rosemarie Hoffman Assistant Professor and Extension Individual and Family Development Specialist, The Texas A&M University System L-2364 12-99 Make a Good Impression Y our goals, self-image, personality, attitude, cleanliness and concern...Edited by Rosemarie Hoffman Assistant Professor and Extension Individual and Family Development Specialist, The Texas A&M University System L-2364 12-99 Make a Good Impression Y our goals, self-image, personality, attitude, cleanliness and concern...

Hoffman, Rosemarie

2000-01-07

102

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

PubMed

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

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

2014-11-01

103

Effect of using polyvinyl alcohol and polyvinyl pyrrolidone in the synthesis of octahedral molecular sieves  

Microsoft Academic Search

Octahedral molecular sieves (OMS-2) have been reported as catalysts for oxidation reactions. Interest exists in improving the properties of these materials. Effects of using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) in the synthesis of OMS-2 have been studied. The structure of OMS-2 was kept when PVA or PVP were used as indicated by XRD and Fourier transform infrared spectra

L. J Garces; B Hincapie; V. D Makwana; K Laubernds; A Sacco; S. L Suib

2003-01-01

104

Impression formation: the role of expressive behavior.  

PubMed

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 spontaneous "explanation." Trained coders measured five separate nonverbal cue factors displayed by the subjects in the videotapes. Groups of untrained judges viewed the tapes and rated their impressions of the subjects on scales of likability, speaking effectiveness, and expressivity-confidence. Male subjects who were nonverbally skilled and extraverted tended to display more outwardly focused and fluid expressive behaviors, and made more favorable impressions on judges, than did males who scored low on the measures of nonverbal skills and extraversion. Females who were nonverbally skilled displayed more facial expressiveness, which led to more favorable initial impressions. Sex differences may reflect basic differences in the acquisition and use of expressive nonverbal cues by males and females. PMID:3517289

Riggio, R E; Friedman, H S

1986-02-01

105

76 FR 5562 - Polyvinyl Alcohol From Taiwan: Final Determination of Sales at Less Than Fair Value  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-583-841] Polyvinyl Alcohol From Taiwan: Final Determination of Sales...has determined that imports of polyvinyl alcohol (PVA) from Taiwan are being, or are...antidumping duty investigation of polyvinyl alcohol from Taiwan. See Polyvinyl Alcohol...

2011-02-01

106

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. PMID:22076600

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

2012-01-01

107

Making a Good (Virtual) First Impression: The Use of Visuals in Online Impression Management  

E-print Network

and Creating Identity Performances Erika Pearson Department of Media, Film and Communication, UniversityMaking a Good (Virtual) First Impression: The Use of Visuals in Online Impression Management elements are becoming an increasingly important component of identity performance on social networking

Paris-Sud XI, Université de

108

Effects of thermal curing conditions on drug release from polyvinyl acetate-polyvinyl pyrrolidone matrices.  

PubMed

This study aimed to investigate the effects of dry and humid heat curing on the physical and drug release properties of polyvinyl acetate-polyvinyl pyrrolidone matrices. Both conditions resulted in increased tablet hardness; tablets stored under humid conditions showed high plasticity and deformed during hardness testing. Release from the matrices was dependent on the filler's type and level. Release profiles showed significant changes, as a result of exposure to thermal stress, none of the fillers used stabilized matrices against these changes. Density of neat polymeric compacts increased upon exposure to heat; the effect of humid heat was more evident than dry heat. Thermograms of samples cured under dry heat did not show changes, while those of samples stored under high humidity showed significant enlargement of the dehydration endotherm masking the glass transition of polyvinyl acetate. The change of the physical and release properties of matrices could be explained by the hygroscopic nature of polyvinyl pyrrolidone causing water uptake; absorbed water then acts as a plasticizer of polyvinyl acetate promoting plastic flow, deformation, and coalescence of particles, and altering the matrices internal structure. Results suggest that humid heat is more effective as a curing environment than dry heat for polyvinyl acetate-polyvinyl pyrrolidone matrices. PMID:20174981

Alkhatib, Hatim S; Hamed, Saja; Mohammad, Mohammad K; Bustanji, Yasser; Alkhalidi, Bashar; Aiedeh, Khaled M; Najjar, Samer

2010-03-01

109

Comparison of elastomeric impression materials' thixotropic behavior.  

PubMed

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

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

2013-06-01

110

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

111

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

112

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

113

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

114

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270...Components of Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section...

2013-04-01

115

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

...2014-04-01 2014-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270...Components of Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section...

2014-04-01

116

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270...Components of Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section...

2011-04-01

117

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Poly(vinyl fluoride) resins. 175.270 Section 175.270...Components of Coatings § 175.270 Poly(vinyl fluoride) resins. Poly(vinyl fluoride) resins identified in this section...

2012-04-01

118

76 FR 13982 - Antidumping Duty Order: Polyvinyl Alcohol From Taiwan  

Federal Register 2010, 2011, 2012, 2013

...A-583-841] Antidumping Duty Order: Polyvinyl Alcohol From Taiwan AGENCY: Import Administration...an antidumping duty order on polyvinyl alcohol (PVA) from Taiwan. DATES: Effective...investigation of PVA from Taiwan. See Polyvinyl Alcohol From Taiwan: Final Determination of...

2011-03-15

119

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

120

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

121

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

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

122

Borescope Device Takes Impressions In Ducts  

NASA Technical Reports Server (NTRS)

Maneuverable device built around borescope equipped to make impression molds of welded joints in interior surfaces of ducts. Molds then examined to determine degress of mismatch in welds. Inserted in duct, and color-coded handles on ends of cables used to articulate head to maneuver around corners. Use of device fairly easy and requires little training.

Walter, Richard F.; Turner, Laura J.

1990-01-01

123

Apparatus for taking odontological or medical impressions  

US Patent & Trademark Office Database

Dental prostheses, such as crowns, inlays or dentures are produced automatically based upon an optical impression taken of the oral region wtih nontraumatic radiation. The reflected waves are transformed into numerical data which is used directly to operate a numerically controlled machine in the fabrication process. The process is pertinent to other medical applications as well.

1986-09-09

124

Impressions of Reform in Ohio Schools.  

ERIC Educational Resources Information Center

This document consists of short reviews of 13 Ohio schools. The goal is to illustrate each school's atmosphere and members through a report made by an education expert who actually visited the school, as opposed to a statistical report. Interviews of students and teachers are included, as are impressions of reform methods being used in the school,…

Kahle, J. B.; Tobin, K. G.; Rogg, S. R.

125

A Modified Impress Method for Beginning Readers.  

ERIC Educational Resources Information Center

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

Saunders, Russell W., Jr.

126

Patterns of Vocalization and Impression Formation  

ERIC Educational Resources Information Center

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

Hayes, Donald P.; Bouma, Gary D.

1975-01-01

127

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

128

Two-dimensional solid state NMR characterization of physisorbed siloxane polymer (OV-225) on silica  

Microsoft Academic Search

Physisorbed cyanopropyl–methyl–phenyl–methyl–siloxane polymer on a silica surface was characterized by one- and two-dimensional solid state NMR techniques including heteronuclear proton–silicon correlation spectroscopy. Spin–lattice relaxations of protons of the siloxane polymer exhibited only small changes upon anchoring to the silica surface indicating somewhat altered molecular dynamics of proton moieties that contribute to the relaxation process. However, the same relaxation rates of

Anima B. Bose; Mahinda Gangoda; Mietek Jaroniec; Roger K. Gilpin; Rathindra N. Bose

2006-01-01

129

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

130

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

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

131

ANIMAL ANALOGIES IN FIRST IMPRESSIONS OF FACES  

PubMed Central

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

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

2013-01-01

132

An alternate impression technique for ocular prostheses.  

PubMed

This article describes an alternative two-step ocular prosthesis impression technique that employs two materials of different consistencies. The method is intended to provide better adaptation to underlying tissues, increased mobility of the prosthesis owing to improvements in facial contours, and improved esthetics, as well as offering the patient greater comfort and security. These advantages and this prosthesis' relative ease of fabrication mean it should be considered as the first step in the management of untreated anophthalmic sockets. PMID:23106824

Goiato, Marcelo Coelho; Dos Santos, Daniela Micheline; Moreno, Amália; Filié Haddad, Marcela; Turcio, Karina Helga Leal

2013-06-01

133

Combinatorial and high-throughput screening of the effect of siloxane composition on the surface properties of crosslinked siloxane-polyurethane coatings.  

PubMed

Libraries of siloxane-polyurethane coatings were designed, formulated, and screened using high-throughput experimentation. Four independent variables that were analyzed were the molecular weight of poly(dimethylsiloxane) (PDMS), presence or absence of poly(epsilon-caprolactone) (PCL) blocks attached to the PDMS backbone, the length of the PCL blocks, and the siloxane polymer level in the coating formulations. In addition to the siloxane libraries (3-aminopropyl-terminated PDMS and poly(epsilon-caprolactone)-poly(dimethylsiloxane)-poly(epsilon-caprolactone) (PCL-PDMS-PCL) triblock copolymers), the coating formulation included a trifunctional isocyanate crosslinker, trifunctional poly(epsilon-caprolactone) polyol, 2,4-pentanedione (pot-life extender), dibutyltin diacetate (catalyst), and a blend of solvents. The resulting coatings were analyzed for their surface energy and pseudobarnacle adhesion both before and after aging the coatings for 30 days in water. The water and methylene iodide contact angle averages increase with increasing molecular weight of PDMS. Coatings prepared from PCL-PDMS-PCL triblock copolymers have lower surface energies than coatings prepared from 3-aminopropyl-terminated PDMS; however, lower pseudobarnacle adhesion results were obtained for the coatings prepared from 3-aminopropyl-terminated PDMS than coatings prepared from PCL-PDMS-PCL triblock copolymers. The siloxane polymer level in the coating formulations does not have a significant effect on the surface energy of the coatings, but it resulted in higher pseudobarnacle adhesion. PMID:17206846

Ekin, Abdullah; Webster, Dean C

2007-01-01

134

Effects of radiofrequency glow discharge on impression material surface wettability  

Microsoft Academic Search

Statement of problem. Argon radiofrequency glow discharge (RGD) may simultaneously sterilize and improve surface wettability of impression materials.Purpose. The purpose of this study was to define RGD technical parameters that influence the surface wettability of impression material (optimization phase). Definition of RGD was followed by an assessment of these optimized RGD parameters on the wettability of four impression materials either

Richard M. Hesby; Chris R. Haganman; Clark M. Stanford

1997-01-01

135

A 3D Impression Acquisition System for Forensic Applications  

E-print Network

. The same technique can also be used in the laboratory to create 3D depth images of suspect tires or shoe of impression evidence such as tire track or shoe impressions. Currently, such evidence is captured by taking). In this paper, we present the design of such an impression imaging device which includes a calibration method

Tuceryan, Mihran

136

A novel chemically selective siloxane polymer for chemical vapor sensing  

NASA Astrophysics Data System (ADS)

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

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

2010-10-01

137

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

138

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

PubMed

Due to the increase in energy cost by constantly high oil prices and the obligation to reduce greenhouse effect gases, landfill gas is frequently used as an alternative energy source for producing heat and electricity. Most of landfill gas utility facilities, however, are experiencing problems controlling siloxanes from landfill gas as their catalytic oxidizers are becoming fouled by silicon dioxide dust. To evaluate adsorption characteristics of siloxanes, an adsorption equilibrium test was conducted and parameters in the Freundlich and Langmuir isotherms were analyzed. Coconut activated carbon (CA1), coal activated carbon (CA2), impregnated activated carbon (CA3), silicagel (NCA1), and activated alumina (NCA2) were used for the adsorption of the mixed siloxane which contained hexamethyldisiloxane (L2), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). L2 had higher removal efficiency in noncarbon adsorbents compared to carbon adsorbents. The application of Langmuir and Freundlich adsorption isotherm demonstrated that coconut based CA1 and CA3 provided higher adsorption capacity on L2. And CA2 and NCA1 provided higher adsorption capacity on D4 and D5. Based on the experimental results, L2, D4, and D5 were converted by adsorption and desorption in noncarbon adsorbents. Adsorption affinity of siloxane is considered to be affect by the pore size distribution of the adsorbents and by the molecular size of each siloxane. PMID:23684695

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

2013-10-01

139

Phoenix Makes an Impression on Mars  

NASA Technical Reports Server (NTRS)

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

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

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

2008-01-01

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

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

Federal Register 2010, 2011, 2012, 2013

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

2013-04-08

142

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

Federal Register 2010, 2011, 2012, 2013

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

2013-07-01

143

Making a Positive Impression in a Negotiation: Gender Differences in Response to Impression Motivation  

Microsoft Academic Search

Prior research has demonstrated the phenomenon of stereotype reactance, whereby men and women behave in contrast to gender stereotypes, when those stereotypes are activated explicitly (Kray, Thompson, & Galinsky, 2001). The authors propose and present an experiment demon- strating a new mechanism for stereotype reactance— namely, impression motivation, or the degree to which people are motivated to control how others

Jared R. Curhan; Jennifer R. Overbeck

2008-01-01

144

Functionalisation of Vinylsubstituted (Poly)Siloxanes and Silsesquioxanes via Cross-Metathesis and Silylative Coupling Transformations  

NASA Astrophysics Data System (ADS)

Applications of the catalytic transformations of vinyl group at silicon, i.e., cross-metathesis, silylative coupling with olefins and silylative coupling with acetylenes for functionalisation of vinylsubstituted (poly)organosiloxanes were overviewed. Cross-metathesis and silylative coupling of olefins with vinylsilicon compounds catalysed by ruthenium complexes were shown to constitute two valuable, complementary synthetic routes leading to functionalised (poly)siloxanes, cyclosiloxanes, silsesquioxanes and spherosilicates of great practical importance. Moreover, first examples of selective synthesis of variety of siloxanes with acetylene functionality via silylative coupling of acetylenes with vinylsiloxanes were described.

Marciniec, Bogdan; Pietraszuk, Cezary

145

Polylactic acid\\/cellulose whisker nanocomposites modified by polyvinyl alcohol  

Microsoft Academic Search

The aim of this study was to produce biodegradable polylactic acid\\/cellulose whisker nanocomposites by compounding extrusion and investigate the possibility to use polyvinyl alcohol to improve the dispersion of whiskers in the matrix. Two feeding methods of polyvinyl alcohol and cellulose nanowhiskers were used and evaluated, dry-mixing with polylactic acid prior extrusion or pumping as suspension directly into the extruder.

Daniel Bondeson; Kristiina Oksman

2007-01-01

146

Complex compound polyvinyl alcohol-titanic acid/titanium dioxide  

NASA Astrophysics Data System (ADS)

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

Prosanov, I. Yu.

2013-02-01

147

Evaluation of Dimensional Stability of Autoclavable Elastomeric Impression Material  

Microsoft Academic Search

Impressions are important sources of cross contamination between patients and dental laboratories. As a part of infection\\u000a control impressions contaminated with variety of micro-organisms via blood and oral secretions should be cleaned and disinfected\\u000a or sterilized before being handled in dental laboratory. The purpose of this study was to determine the effect of autoclaving\\u000a on dimensional stability of elastomeric impression

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

2011-01-01

148

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

PubMed

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

Surita, Sharon C; Tansel, Berrin

2014-04-01

149

Adsorption and Thermogravimetric Studies of Mesoporous Silica Coated with Siloxane Polymer  

Microsoft Academic Search

Nitrogen adsorption and high-resolution thermogravimetry were used to study a series of samples prepared by coating porous silica with different amounts of siloxane polymer. Thermogravimetry was employed to investigate the thermal behavior of the coated samples as well as the polymer–silica interactions. Nitrogen adsorption was used to monitor the changes in the specific surface area, porosity, and surface properties upon

Anima Bose; Roger K. Gilpin; Mietek Jaroniec

2001-01-01

150

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

PubMed

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

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

2013-08-01

151

Polymer-supported siloxane transfer agents for Pd-catalyzed cross-coupling reactions.  

PubMed

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

Nguyen, Minh H; Smith, Amos B

2013-08-16

152

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

PubMed Central

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

Nguyen, Minh H.

2013-01-01

153

Characterization of irradiance effects on curing of siloxane for embedded waveguide applications  

NASA Astrophysics Data System (ADS)

In order to maintain the overall optical performance in a step index rectangular waveguide, the complex index of refraction of the core and cladding material must be maintained throughout the cycle of the lithographic fabrication process. The percentage of the core and cladding material that is cured and the irradiance that cure took place directly affects the complex index of refraction of these materials. Siloxanes produced by Dow Corning have been selected to meet the requirements for embedded waveguides for circuit board applications due to their optical performance characteristics and their compatibility with current manufacturing techniques. The required total dose for a 50 ?m thick layer of siloxane is 1200 mJ at an irradiance of 30 mW/cm2. In order to utilize lower irradiance levels the total dose of the ultraviolet exposure must be characterized and calibrated. By measuring the changes in the absorption peaks of the materials using transmission data from ellipsometric techniques it is possible to define the percentage cure of the siloxane from different curing profiles. Ellipsometric techniques were also utilized to measure the complex refractive index of the materials cured using different profiles. It was found that the total dose required for a complete cure and the complex refractive index of these materials drastically changes with different irradiances and the profile for the total dose compared to the curing of the siloxane materials at all irradiances is logarithmic.

Daunais, Thomas; Walczak, Karl; Middlebrook, Chris; Bergstrom, Paul

2011-01-01

154

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

PubMed Central

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

Nguyen, Minh H.; Smith, Amos B.

2013-01-01

155

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 ...

156

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. PMID:24550571

Holoien, Deborah Son; Fiske, Susan T.

2014-01-01

157

Titration of free hydroxyl and strained siloxane sites on silicon dioxide with fluorescent probes.  

PubMed

A technique enabling the detection and quantification of low density sites on planar SiO2 surfaces is demonstrated. Fluorescent probes are used to titrate free hydroxyl and strained siloxane sites on the surface of amorphous SiO2 substrates in vacuum. The titration of free hydroxyl sites was performed to validate the method and to provide a reference for the measurement of the strained siloxane site density. Perylene derivatives with different functional groups are chemisorbed onto the surface sites, enabling in situ photoluminescence (PL) measurements of the bound fluorophores. An amine functional group is used to selectively titrate strained siloxane sites, while an alcohol group is used for the titration of free hydroxyl sites. Emission intensity was found to be nonlinear with coverage for bound fluorophore densities greater than 0.1 nm(-2), necessitating the removal of molecules from the surface into a solution to obtain accurate density measurements. For lower densities, the coverage of bound fluorophores can be estimated directly from in situ PL measurements. The measured areal densities of bound fluorophores after titrating free hydroxyl sites are in good agreement with literature values for the densities of such sites on high surface area silica. PL measurements of SiO2 surfaces titrated with an amine derivative of perylene indicate that strained siloxane sites exist for vacuum pretreatment temperatures of 300 °C and increase with increasing pretreatment temperature. Densities of strained siloxane sites on the silica surface are estimated at 0.004-0.02 nm(-2) for pretreatment temperatures of 300-700 °C, demonstrating the sensitivity of this technique. PMID:23978272

McCrate, Joseph M; Ekerdt, John G

2013-09-24

158

Characterization of siloxane adsorbates covalently attached to TiO2  

NASA Astrophysics Data System (ADS)

Siloxanes with the general formula R-(CH2)n-Si-(OR')3 form durable bonds with inorganic materials upon hydrolysis of labile -OR' groups, and serve as robust coupling agents between organic and inorganic materials. In the field of dye-sensitized solar cells, functionalization of TiO2 thin-films with siloxane adsorbates has been shown to be useful as a surface-passivation technique that hinders recombination processes and improves the overall efficiency of light-to-electricity conversion. However, the attachment of siloxane adsorbates on TiO2 surfaces still remains poorly understood at the molecular level. In this paper, we report the characterization of 3-(triethoxysilyl) propionitrile (TPS) adsorbates, covalently attached onto TiO2 surfaces. We combine synthetic methods based on chemical vapor deposition, Fourier transform (FT) infrared (IR) spectroscopy and electronic structure calculations based on density functional theory (DFT). We predict that trifunctional siloxanes form only 2 covalent bonds, in a 'bridge' mode with adjacent Ti4+ ions on the TiO2 surface, leaving 'dangling' alkoxy groups on the surface adsorbates. Our findings are supported by the observation of a prominent fingerprint band at 1000-1100 cm-1, assigned to Si-O-C stretching modes, and by calculations of binding enthalpies at the DFT B3LYP/(LACVP/6-31G**) level of theory indicating that the 'bridge' binding (?Hb= -55 kcal mol-1) is more stable than 'tripod' motifs (?Hb= -45 kcal mol-1) where siloxanes form 3 covalent bonds with the TiO2 surface. The alkoxysiloxane groups are robust under heat and water treatment and are expected to be particularly relevant for analytical methods since they could be exploited for immobilizing other functionalities onto the TiO2 surfaces.

Iguchi, Nobuhito; Cady, Clyde; Snoeberger, Robert C., III; Hunter, Bryan M.; Sproviero, Eduardo M.; Schmuttenmaer, Charles A.; Crabtree, Robert H.; Brudvig, Gary W.; Batista, Victor S.

2008-08-01

159

Effect of mixing technique on surface characteristics of impression materials  

Microsoft Academic Search

Statement of problem. Previous studies have shown a relationship between the disinfection process, wettability, and mass change of impression materials. Hand-mixed high viscosity impression materials usually result in a material with numerous voids, which contribute to surface roughness and affect the surface characteristics of the material.Purpose. This study evaluated the effect of mixing technique on advancing contact angle, receding contact

Xavier Lepe; Glen H. Johnson; John C. Berg; Tar C. Aw

1998-01-01

160

Country music as impression management: A meditation on fabricating authenticity  

Microsoft Academic Search

Without using Goffman's well-known theory of impression management in any conscious way, Richard Peterson, in his Creating country music: Fabricating authenticity (1997), demonstrated that impression management was a central process in creating country music. The present study explicitly links Peterson's ideas about the fabrication of authenticity to Goffman's Presentation of self in everyday life (1959) in an attempt to show

Michael Hughes

2000-01-01

161

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. PMID:24223432

Koppensteiner, Markus

2013-01-01

162

Formulation of glutaraldehyde disinfectant for alginate impressions.  

PubMed

The effect of buffer agents incorporated in glutaraldehyde disinfectants on the surface quality of dental models was examined by the measurement of surface roughness, X-ray diffraction analysis and SEM observation. Seven experimental glutaraldehyde disinfectants were prepared using two buffer agents, potassium acetate alone or potassium acetate and sodium hydrogen carbonate in combination. Four kinds of sulfate--zinc, calcium, potassium and magnesium sulfate--were added to these disinfectants in order to accelerate the hydration of calcium sulfate hemihydrate. The impressions treated with the experimental disinfectants for 1 h produced stone surfaces which had significantly lower surface roughness values than those treated with the commercial disinfectants (p < 0.05). The X-ray diffraction analysis and SEM observation showed that these superior surfaces were produced as a result of significant reductions in the amount of residual calcium sulfate hemihydrate. Replacement of buffer agents in commercial glutaraldehyde disinfectants with chemicals such as those studied in the present study will improve the surface quality of dental stone. PMID:10786155

Unemori, M; Matsuya, Y; Matsuya, S; Akashi, A; Mizuno, K; Akamine, A

1999-12-01

163

[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

164

Wettability of a hydrophilic addition silicone impression material.  

PubMed

Silicone impression materials, long noted for their poor wettability, have typically demonstrated contact angles with water greater than 90 degrees. This study compared the wettability of a new hydrophilic addition silicone with that of other impression materials. Specimens from various viscosities of polyether, polysulfide, hydrophobic addition silicone, and hydrophilic addition silicone were formed against a smooth surface. The advancing contact angle of a saturated aqueous solution of CaSO4 on the impression materials was measured after 1 minute. Mean contact angles were calculated and results were analyzed by ANOVA and a multiple comparison of means procedure. Differences between pairs of contact angle means were found to be statistically significant except for the polyether-hydrophilic addition silicone pair. The wettability of the hydrophilic addition silicone impression material was found to be not significantly different from that of a polyether impression material. PMID:2654364

Pratten, D H; Craig, R G

1989-02-01

165

Influence of the molar ratio of tetraethoxysilane and glycidoxypropyltriethoxysilane on the properties of anhydride-cured epoxy-siloxane composites  

Microsoft Academic Search

The topological structure of epoxy-siloxane composites prepared by anhydride curing was studied in relation to the molar ratio\\u000a of glycidoxypropyltriethoxysilane and tetraethoxysilane and to the total content of siloxane components of the system. The\\u000a optical characteristics, glass transition point, sol fraction yield, concentration of internodal chains, and maximal rate\\u000a of oxygen uptake by the hybrid materials were determined.

S. V. Zhil’tsova; V. M. Mikhal’chuk; V. A. Beloshenko; A. V. Kirilash

2009-01-01

166

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

167

Physical and biological properties of a novel siloxane adhesive for soft tissue applications.  

PubMed

The aim of this study was to investigate the adhesive properties of an in-house aminopropyltrimethoxysilane-methylenebisacrylamide (APTMS-MBA) siloxane system and compare them with a commercially available adhesive, n-butyl cyanoacrylate (nBCA). The ability of the material to perform as a soft tissue adhesive was established by measuring the physical (bond strength, curing time) and biological (cytotoxicity) properties of the adhesives on cartilage. Complementary physical techniques, X-ray photoelectron spectroscopy, Raman and infrared imaging, enabled the mode of action of the adhesive to the cartilage surface to be determined. Adhesion strength to cartilage was measured using a simple butt joint test after storage in phosphate-buffered saline solution at 37 degrees C for periods up to 1 month. The adhesives were also characterised using two in vitro biological techniques. A live/dead stain assay enabled a measure of the viability of chondrocytes attached to the two adhesives to be made. A water-soluble tetrazolium assay was carried out using two different cell types, human dermal fibroblasts and ovine meniscal chondrocytes, in order to measure material cytotoxicity as a function of both supernatant concentration and time. IR imaging of the surface of cartilage treated with APTMS-MBA siloxane adhesive indicated that the adhesive penetrated the tissue surface marginally compared to nBCA which showed a greater depth of penetration. The curing time and adhesion strength values for APTMS-MBA siloxane and nBCA adhesives were measured to be 60 s/0.23 MPa and 38 min/0.62 MPa, respectively. These materials were found to be significantly stronger than either commercially available fibrin (0.02 MPa) or gelatin resorcinol formaldehyde (GRF) adhesives (0.1 MPa) (P < 0.01). Cell culture experiments revealed that APTMS-MBA siloxane adhesive induced 2% cell death compared to 95% for the nBCA adhesive, which extended to a depth of approximately 100-150 microm into the cartilage surface. The WST-1 assay demonstrated that APTMS-MBA siloxane was significantly less cytotoxic than nBCA adhesive as an undiluted conditioned supernatant (P < 0.001). These results suggest that the APTMS-MBA siloxane may be a useful adhesive for medical applications. PMID:15887653

Wilson, D J; Chenery, D H; Bowring, H K; Wilson, K; Turner, R; Maughan, J; West, P J; Ansell, C W G

2005-01-01

168

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

PubMed

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

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

2015-01-01

169

Polyvinyl alcohol cross-linked with two aldehydes  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

170

Hologram with dichromated polyvinyl alcohol and natural colorant  

NASA Astrophysics Data System (ADS)

We showing some properties using materials as dichromate polyvinyl alcohol (DC-PVA), it is doped with natural colorant, it were investigated and compared to the pure dichromated polyvinyl alcohol. The material increasing the sensibility, and present a good photo sensibility Preliminary studies shows, some properties with the ability to storage information, and present a technique to obtain holograms with these colored materials, and some experimental results. The best advantage of this DYE-DC-PVA holograms is the speed of recording.

Páez-Trujillo, G.; Olivares-Pérez, A.; Mejias-Brizuela, N.; Garay-Hernández, M. P.; Fontanilla-Urdaneta, R.; Fuentes-Tapia, I.; Amigón-De León, E.

2007-09-01

171

In Situ Cross-Linking of Polyvinyl Alcohol Films  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

172

Strategies for managing impressions of racial identity in the workplace.  

PubMed

This article deepens understanding of the workplace experiences of racial minorities by investigating racial identity-based impression management (RIM) by Asian American journalists. Racial centrality, directly or indirectly, predicted the use of 4 RIM strategies (avoidance, enhancement, affiliation, and racial humor). Professional centrality also predicted strategy use, which was related to life satisfaction and perceived career success. By shedding light on proactive strategies that individuals use to influence colleagues' impressions of their racial identity, we contribute to research on diversity in organizations, impression management, and racial identity. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25090148

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

2014-10-01

173

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

174

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

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

175

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

NASA Astrophysics Data System (ADS)

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

Kowalewska, Anna; Delczyk, Bogumi?a

176

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

Microsoft Academic Search

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

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

2010-01-01

177

21 CFR 872.3670 - Resin impression tray material.  

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3670...resin impression tray material is applied to this preliminary study model to form a custom tray. This tray is then filled...

2014-04-01

178

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

179

Coping with stereotype threat: Denial as an impression management strategy  

E-print Network

) 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 of denying cognitive incompetence, which emerged primarily when they were...

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

2005-01-01

180

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

181

First Impressions in Business Settings By: Kimberly Rogers  

E-print Network

display our identities to others? #12;Asking Questions... What Are Your Very First Impressions or Opinions to emotions experienced. #12;Clothing "He's alright, his shirt looks wrinkled, and his tie is crooked

New Hampshire, University of

182

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

183

Deceptive Impression Management: Does Deception Pay in Established Workplace Relationships?  

Microsoft Academic Search

We examine deceptive impression management’s effect on a supervisor’s ratings of promotability and relationship quality (i.e.,\\u000a leader–member exchange) via the mediating role of the supervisor’s recognition of deception. Extending ego depletion theory\\u000a using social information processing theory, we argue that deceptive impression management in a supervisor-subordinate relationship\\u000a is difficult to accomplish and the degree that deception is detected will negatively

John R. Carlson; Dawn S. Carlson; Merideth Ferguson

2011-01-01

184

Choosing to Sever or Maintain Association Induces Biased Impression Formation  

Microsoft Academic Search

Impression formation should be biased in individuals who decide to maintain or sever association because they desire to form impressions that support their decision. Because such individuals also should wish to appear objective, decision-supporting information should be irrelevant to obvious reasons for the decision (e.g., a target's social stigma). Accepting the veracity of the target's stereotype-irrelevant attributes supports the decision

Janet B. Ruscher; Elizabeth Yost Hammer

1996-01-01

185

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

186

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

NASA Astrophysics Data System (ADS)

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

Fu, Zhidong

187

Poly(vinyl alcohol) and poly(vinyl pyrrolidone) blended films for local nitric oxide release.  

PubMed

The nitric oxide (NO) donor S-nitrosoglutathione (GSNO) was incorporated in solid polymeric films of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP) and blended PVA/PVP. These matrices were found to provide a great stabilization effect on the thermal decomposition of GSNO, leading to 8-16-fold reduction in the first-order rate constants of NO release, compared to aqueous GSNO solutions. PVA/PVP-GSNO released 90% of the NO supply, over a time period of 24h at 37 degrees C. Differential scanning calorimetry has confirmed the miscibility between the two polymeric components. Stress-strain analysis has shown an improvement of the mechanical property of PVA films in the PVA/PVP blend, which leads to an increase of 25% in the stress at break. Scanning electron microscopy has shown that the PVA/PVP-GSNO blend leads to a smooth coating of metallic surfaces. These properties, allied to the already known good biocompatibility of PVA and PVP, makes GSNO-containing PVA and PVA/PVP blend films good candidates for the local and controlled release of NO in target areas. PMID:15020153

Seabra, Amedea Barozzi; De Oliveira, Marcelo Ganzarolli

2004-08-01

188

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

PubMed

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

Oh, Won-suk; Park, Ju-mi

2014-08-01

189

Margin adaptation of indirect composite inlays fabricated on flexible dies  

Microsoft Academic Search

Statement of problem. Indirect composite restorations can be made in 1 appointment using a flexible die. Interactions between different impression materials and flexible die materials may affect the accuracy of fit and margin adaptation of the restoration. Purpose. This study compared the margin adaptation of composite inlays made using the following 5 impression\\/flexible die material combinations; condensation silicone\\/polyvinyl siloxane (CS\\/PVS),

Richard B. Price; Jack D. Gerrow

2000-01-01

190

75 FR 55552 - Polyvinyl Alcohol From Taiwan: Preliminary Determination of Sales at Less Than Fair Value and...  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-583-841] Polyvinyl Alcohol From Taiwan: Preliminary Determination...preliminarily determines that sales of polyvinyl alcohol (PVA) from Taiwan are being, or are...Dumping Duty Investigation: Polyvinyl Alcohol From Taiwan, 69 FR 59204 (October...

2010-09-13

191

78 FR 37794 - Polyvinyl Alcohol from Taiwan: Final Results of Antidumping Duty Administrative Review; 2010-2012  

Federal Register 2010, 2011, 2012, 2013

...Administration [A-583-841] Polyvinyl Alcohol from Taiwan: Final Results of Antidumping...the antidumping duty order on polyvinyl alcohol (PVA) from Taiwan. For these final...1\\ See Polyvinyl Alcohol From Taiwan: Preliminary Results of...

2013-06-24

192

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

PubMed

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

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

2013-05-01

193

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

... false Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl amino...carbonyl]-2-oxo-1-pyrrolidinyl] propyl Me. 721.9517 Section 721.9517 Protection...9517 Siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethyl...

2010-07-01

194

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

195

The polyvinyl alcohol sponge model implantation.  

PubMed

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

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

2012-01-01

196

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

Microsoft Academic Search

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

Jerker Denrell

2005-01-01

197

Polyvinyl alcohol battery separator containing inert filler. [alkaline batteries  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

198

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

PubMed

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

Storey, D; Coward, T J

2013-06-01

199

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

E-print Network

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

Mather, Patrick T.

200

Novel ionic iodide-siloxane hybrid electrolyte for dye-sensitized solar cells.  

PubMed

A novel ionic siloxane hybrid electrolyte was fabricated by thermal polymerization of iodide-oligosiloxane resin. The nanosized iodide-oligosiloxane was synthesized by a simple sol-gel condensation of 3-iodopropyltrimethoxysilane and diphenylsilanediol. It is found that the composition and concentration of the oligosiloxane used in the electrolyte affect the performance of the dye-sensitized solar cells (DSSCs). An optimized DSSC with the hybrid electrolyte using smaller molecular-sized oligosiloxane with a greater amount of iodide groups presented solar to electricity conversion efficiency of 5.2% at 1 sunlight (100 mW cm(-2)), which is comparable to that afforded by a liquid electrolyte. PMID:21192684

Jung, KyungHo; Bae, Jun-Young; Yun, Ho-Gyeong; Kang, Man Gu; Bae, Byeong-Soo

2011-02-01

201

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

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

202

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

203

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

204

Respiratory illness caused by overheating of polyvinyl chloride  

Microsoft Academic Search

On 9 August 1979, 62 (30.8%) of 201 workers and one of 60 management personnel in a polyvinyl chloride (PVC) fabricating plant developed acute upper and lower respiratory irritation, headache, nausea, and fainting. All were taken to hospital; none died. Sixty of the patients were women. Interviews two weeks later with 57 affected and 14 unaffected workers disclosed that illness

B Froneberg; P L Johnson; P J Landrigan

1982-01-01

205

Evaluation of a Polyvinyl Toluene Neutron Counter Array  

Microsoft Academic Search

The purpose of this article is to simulate the performance of a neutron detector array for empirical configuration optimization and preliminary algorithm evaluation. Utilizing a compact array of borated Polyvinyl Toluene light pipes and Photomultiplier Tubes, pulse shape analysis, standard spectral histogramming, and multiplicity counting can enable neutron measurements for multiple applications. Results demonstrate that analysis with Monte Carlo N-Particle

Robert Hayes

2008-01-01

206

Synthesis of Modified Poly(vinyl acetate) Adhesives  

Microsoft Academic Search

Modified poly(vinyl acetate) copolymers with drying oils as comonomers have been prepared. The unsaturated triglycerides can produce cross-linking and give a waterproof effect due to their hydrophobicity. The new copolymers synthesized by solution polymerization in an organic medium have been submitted to analytical characterization in order to investigate the role of the drying oils in the polymerization reaction. NMR spectroscopy

A. Salvini; L. M. Saija; M. Lugli; G. Cipriani; C. Giannelli

2010-01-01

207

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...

208

1 INTRODUCTION In Spain, Plasticized polyvinyl chloride (PVC-  

E-print Network

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

Zornberg, Jorge G.

209

How Sexual Orientation and Physical Attractiveness Affect Impressions of Males.  

ERIC Educational Resources Information Center

Stereotyped impressions of male homosexuals and the underlying importance of sexuality in social attraction and perceptions were investigated. Male (N=80) and female (N=80) college students responded to either an attractive or an unattractive photo of a male stimulus person, who was identified to half of the subjects as a homosexual. Compared to…

Elman, Donald; And Others

210

Third-Person Perception as an Impression Management Tactic  

Microsoft Academic Search

The current research aims at broadening the motivational explanations for the third-person perception (TPP) by documenting the role of impression management motives in this perception. In two experiments that were devised to explore this possibility, participants were asked to report in public or in private on their perceptions of how various advertisements affected them and others. In addition, their level

Nurit Tal-Or; Dorit Drukman

2010-01-01

211

First Impressions in a Glowing Host-Microbe Partnership  

E-print Network

#12;First Impressions in a Glowing Host-Microbe Partnership Jennifer J. Wernegreen1,* 1Nicholas://dx.doi.org/10.1016/j.chom.2013.07.015 Despite the clear significance of beneficial animal-microbe associations & Microbe, Kremer et al. (2013) reveal that first contact within the squid-vibrio symbiosis triggers

McFall-Ngai, Margaret

212

Temporary Employment and Perceived Employability: Mediation by Impression Management  

ERIC Educational Resources Information Center

Perceived employability (PE) has been advanced as the upcoming resource for career development, particularly for temporary workers. The question is how temporary workers become employable. Our hypothesis is that temporary workers more than permanent workers use impression management to become employable, both on the internal and the external labor…

De Cuyper, Nele; De Witte, Hans

2010-01-01

213

Establishing the posterior palatal seal during the final impression stage.  

PubMed

A procedure for adding a posterior palatal seal at the final impression stage with green stick modeling compound is described. The location and degree of tissue displacement of the posterior palatal seal area are controlled by the dentist. This procedure is suggested to be more accurate than the arbitrary scraping of the master cast. PMID:9297652

Ansari, I H

1997-09-01

214

Establishing the posterior palatal seal during the final impression stage  

Microsoft Academic Search

A procedure for adding a posterior palatal seal at the final impression stage with green stick modeling compound is described. The location and degree of tissue displacement of the posterior palatal seal area are controlled by the dentist. This procedure is suggested to be more accurate than the arbitrary scraping of the master cast. (J Prosthet Dent 1997;78: 324-6.)

Izharul Haque Ansari

1997-01-01

215

Shared impression formation in the cognitively interdependent dyad.  

PubMed

We examined the role of cognitive interdependence in determining how close friends form shared impressions of another person. Cognitive interdependence should provide a processing advantage, such that close friends are more efficient in forming shared impressions and are more successful at doing so. Under normal circumstances, the conversations of close friends should be marked by little necessity to make explicit requests for information, mutual recognition of who currently is controlling the flow of conversation, and willingness to express differences in opinion. Given these advantages, close friends also should be able to form complex shared impressions that go beyond mere one-sided stereotypic judgments and that instead resolve apparent discrepancies in the target's personality. However, if the cognitive interdependence system is disrupted by mutual distraction, these advantages should attenuate or even reverse. Dyads of varying degrees of closeness were mutually distracted or not while discussing their impressions of another female college student. Results supported predictions and are discussed with reference to how cognitive interdependence may help close dyads function within their mutual social networks. PMID:14567845

Ruscher, Janet B; Santuzzi, Alecia M; Hammer, Elizabeth Yost

2003-09-01

216

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

217

Modeling first impressions from highly variable facial images.  

PubMed

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

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

2014-08-12

218

Impressions of a Disclosing Other Following Own Disclosing.  

ERIC Educational Resources Information Center

The effects of an instigator's and a respondent's disclosure on impressions of the revealing respondent were examined in a pair of experiments. The first experiment assessed the effects of both own and other's disclosure on a participant perceiver. After meeting a confederate partner, female undergraduate subjects (N=83) were induced to make an…

Archer, Richard L.; And Others

219

Effects of Positive Impression Management on the Psychopathic Personality Inventory  

Microsoft Academic Search

The Psychopathic Personality Inventory (PPI; S. O.Lilienfeld & B. P. Andrews, 1996) is a self-report test that has shown considerable promise as a screening measure for psychopathy. A current limitation of the PPI is that no data exist regarding the impact of response sets such as positive impression management. Although the PPI contains a validity scale (Unlikely Virtues) designed to

John F. Edens; Jacqueline K. Buffington; Tara L. Tomicic; Brandon D. Riley

2001-01-01

220

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

E-print Network

, German and sometimes even Spanish and Chinese." Zhang Jinsu, Beijing Institute of Technology, China "The unforgettable memory and an amazing impression of TUM and the city." Yarui Fu, Tongji University, China About on satellite geod- esy or at Straubing Center of Science focusing on renewable resources · International

221

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

E-print Network

, German and sometimes even Spanish and Chinese." Zhang Jinsu, Beijing Institute of Technology, China "The unforgettable memory and an amazing impression of TUM and the city." Yarui Fu, Tongji University, China Contact in space engineering and satellite ap- plications related to navigation. Students should have completed

Wu, Yih-Min

222

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

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

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

223

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

224

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

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

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

PubMed

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

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

2014-02-01

227

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

PubMed

The objectives of this study were to compare the types and levels of volatile methyl siloxanes (VMS) present in biogas generated in the anaerobic digesters and landfills, evaluate the energetics of siloxane transformations under anaerobic conditions, compare the conditions in anaerobic digesters and municipal solid waste (MSW) landfills which result in differences in siloxane compositions. Biogas samples were collected at the South District Wastewater Treatment Plant and South Dade Landfill in Miami, Florida. In the digester gas, D4 and D5 comprised the bulk of total siloxanes (62% and 27%, respectively) whereas in the landfill gas, the bulk of siloxanes were trimethylsilanol (TMSOH) (58%) followed by D4 (17%). Presence of high levels of TMSOH in the landfill gas indicates that methane utilization may be a possible reaction mechanism for TMSOH formation. The free energy change for transformation of D5 and D4 to TMSOH either by hydrogen or methane utilization are thermodynamically favorable. Either hydrogen or methane should be present at relatively high concentrations for TMSOH formation which explains the high levels present in the landfill gas. The high bond energy and bond distance of the Si-O bond, in view of the atomic sizes of Si and O atoms, indicate that Si atoms can provide a barrier, making it difficult to break the Si-O bonds especially for molecules with specific geometric configurations such as D4 and D5 where oxygen atoms are positioned inside the frame formed by the large Si atoms which are surrounded by the methyl groups. PMID:25160660

Tansel, Berrin; Surita, Sharon C

2014-11-01

228

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. PMID:25061529

Karam Genno, N.; Assaf, A.

2014-01-01

229

A hybrid impressed current and galvanic cathodic protection system  

SciTech Connect

This paper outlines the design and installation of a cathodic protection (CP) system for the support pilings and beams for a commercial building situated over brackish water. The CP system is comprised of an impressed current expanded titanium jacket system for the pilings and a galvanic thermally sprayed (metalized) zinc system for the beams. The impressed current CP system is powered and controlled via a distributed rectifier system (DRS). The DRS consists of an array of local rectifier units (LRU'S). Each of the LRU'S possess 10 channels which may be configured as outputs or inputs depending on the system design. All of the DRS control and monitoring operations are carried out digitally using a PC. The scope of this document includes background information, system design, system description, and energizing procedures.

Sitton, I.; Costa, J.E.

1999-07-01

230

First impressions: gait cues drive reliable trait judgements.  

PubMed

Personality trait attribution can underpin important social decisions and yet requires little effort; even a brief exposure to a photograph can generate lasting impressions. Body movement is a channel readily available to observers and allows judgements to be made when facial and body appearances are less visible; e.g., from great distances. Across three studies, we assessed the reliability of trait judgements of point-light walkers and identified motion-related visual cues driving observers' judgements. The findings confirm that observers make reliable, albeit inaccurate, trait judgements, and these were linked to a small number of motion components derived from a Principal Component Analysis of the motion data. Parametric manipulation of the motion components linearly affected trait ratings, providing strong evidence that the visual cues captured by these components drive observers' trait judgements. Subsequent analyses suggest that reliability of trait ratings was driven by impressions of emotion, attractiveness and masculinity. PMID:22717166

Thoresen, John C; Vuong, Quoc C; Atkinson, Anthony P

2012-09-01

231

e-Perceptions: Personality Impressions Based on Personal Websites  

Microsoft Academic Search

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

Simine Vazire; Samuel D. Gosling

2004-01-01

232

The relationship of clients’ social class to early therapeutic impressions  

Microsoft Academic Search

Using case vignettes that differed in the presentation of the client's social class, the influence of social class on therapeutic impressions was studied in the context of just-world beliefs. Results suggested that (1) participants with higher levels of belief in a just world saw poor and working-class clients as more unpleasant to work with and more dysfunctional and (2) working-class

Laura Smith; Susan Mao; Seth Perkins; Marilyn Ampuero

2011-01-01

233

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

234

Emotion in the Neutral Face: A Mechanism for Impression Formation?  

PubMed Central

The current work examined contributions of emotion-resembling facial cues to impression formation. There exist common facial cues that make people look male or female, emotional, and from which we derive personality inferences. We first conducted a Pilot study to assess these effects. We found that neutral female versus neutral male faces were rated as more submissive, affiliative, naïve, honest, cooperative, babyish, fearful, happy, and less angry than neutral male faces. In our Primary Study, we then “warped” these same neutral faces over their corresponding anger and fear displays so the resultant facial appearance cues now structurally resembled emotion while retaining a neutral visage (e.g., no wrinkles, furrows, creases etc.). The gender effects found in the Pilot Study were replicated in the Primary Study, suggesting clear stereotype driven impressions. Critically, ratings of the neutral-over-fear warps versus neutral-over-anger warps also revealed a profile similar to the gender-based ratings, revealing perceptually driven impressions directly attributable to emotion overgeneralization. PMID:22471850

Adams, Reginald B.; Nelson, Anthony J.; Soto, Jose A.; Hess, Ursula; Kleck, Robert E.

2012-01-01

235

Cross-linked polyvinyl alcohol and method of making same  

NASA Technical Reports Server (NTRS)

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

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

1981-01-01

236

Cross-linked polyvinyl alcohol films as alkaline battery separators  

Microsoft Academic Search

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

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

1983-01-01

237

Crosslinkable poly(vinyl acetate) emulsions for wood adhesive  

Microsoft Academic Search

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

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

2011-01-01

238

Sol-Gel Synthesis of Au-Nanoparticle Dispersed Bicontinuous Macroporous Siloxane Gel  

NASA Astrophysics Data System (ADS)

We synthesized Au-nanoparticle dispersed siloxane gel with well-defined bicontinuous macroporous morphologies. We employed methyltrimethoxysilane (MTMS) as a precursor of the gel skeleton, and also employed hydrogen tetrachloroaurate(III) as both a precursor of Au nanoparticles and an acid catalyst for hydrolysis/condensation of methoxysilanes. The effect of adding (3-mercaptopropyl)trimethoxysilane (MPTMS) as a starting material on the obtained structure was also investigated. It is found that Au nanoparticles of 20-30 nm in grain size are uniformly dispersed on the gel surface in the system containing MPTMS; in contrast, Au nanoparticles assembled in the pits in the MPTMS-free system. All the heat-treated MPTMS-containing gels showed surface plasmon absorption, and the peaks shifted from 550 to 520 nm with increasing the calcination temperature.

Hamada, Y.; Nishi, M.; Shimotsuma, Y.; Miura, K.; Hirao, K.

2011-10-01

239

Transparent and robust siloxane-based hybrid lamella film as a water vapor barrier coating.  

PubMed

Water vapor barriers are important in various application fields, such as food packaging and sealants in electronic devices. Polymer/clay composites are well-studied water vapor barrier materials, but their transparency and mechanical strength degrade with increasing clay loading. Herein, we demonstrate films with good water vapor barrier properties, high transparency, and mechanical/thermal stability. Water vapor barrier films were prepared by the solution crystallization of siloxane hybrid lamellae. The films consist of highly crystallized organic/inorganic hybrid lamellae, which provide high transparency, hardness, and thermal stability and inhibit the permeation of water vapor. The water permeability of a 6 ?m thick hybrid film is comparable to that of a 200 ?m thick silicon rubber film. PMID:25296395

Tokudome, Yasuaki; Hara, Takaaki; Abe, Risa; Takahashi, Masahide

2014-11-12

240

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

Code of Federal Regulations, 2010 CFR

...Siloxanes and silicones, 3-[(2-aminoethyl) amino]propyl Me, di-Me, reaction products with polyethylene-polypropylene glycol...and silicones, 3-[(2-aminoethyl) amino]propyl Me, di-Me, reaction products with...

2010-07-01

241

Exploring the Ways that Adolescents Form and Perpetuate Impressions of Their Teachers  

ERIC Educational Resources Information Center

This study used qualitative methodology including observations and interviews to attempt to discover how secondary students form impressions of their teachers and how those impressions are perpetuated among students, leading to teacher reputation. The findings from the study indicate that students form impressions of their teachers by assessing…

Kucinski, Steven Jon

2010-01-01

242

A functional open-tray impression technique for implant-retained overdenture prostheses.  

PubMed

Several implant impression techniques with different materials have been described in the literature. Generally, border molding, functional, and final impressions have been made with 3 different materials, which makes the procedure technique-sensitive and time-consuming. A combination of open-tray and functional impression techniques is described in this technical report. Border molding and functional impression procedures are made at the same time using a vinyl polysiloxane impression material, which makes this technique a simple and time-efficient alternative for clinicians. PMID:21651416

Ozcelik, Tuncer Burak; Yilmaz, Burak

2012-10-01

243

Wettability changes in polyether impression materials subjected to immersion disinfection  

PubMed Central

Background: Disinfection of impression materials prevents cross-contamination; however, the disinfectants may alter the wettability property. The purpose of this investigation was to evaluate the wettability changes of polyether impression material after immersing in four different chemical disinfectant solutions for a period of 10 min and 30 min, respectively. Materials and Methods: A total of 45 samples of polyether dental impression material (Impregum soft, 3MESPE, St. Paul, MN, USA) were randomly divided into nine groups with five specimens each. Each specimen was disc shaped, flat of 32 mm diameter and 3 mm thickness. The samples were immersed in four disinfectant solutions: 2% Glutaraldehyde, 5% sodium hypochlorite, 0.05% iodophor, and 5.25% phenol for 10 min and 30 min, respectively. The control was without disinfection. Wettability of the samples was assessed by measuring the contact angle by using the Telescopic Goniometer. Data were subjected to analysis of variance (Fisher's test) and Tukey's post hoc test for multiple comparisons at 5% level of significance. Results: The contact angle of 20.21° ± 0.22° were recorded in the control samples. After 10 min, the samples that were immersed in 5% sodium hypochlorite and 5.25% phenol showed significant statistical increase in the contact angle as compared to the control (P < 0.001). After 30 min of disinfection, only the samples immersed in 0.05% iodophor showed there were no significant changes in the contact angle, whereas the other disinfectants significantly increased the contact angle and decreased the wettability of the polyether material. Conclusion: Within the limitations of the study, 2% glutaraldehyde proved safe for 10 min of immersion disinfection while 0.05% iodophor holds promise as an effective disinfectant without affecting the wettability of the material. PMID:24130593

Shetty, Shweta; Kamat, Giridhar; Shetty, Rajesh

2013-01-01

244

Preliminary impressions in microstomia patients: an innovative technique.  

PubMed

Microstomia has been defined as an abnormally small oral orifice associated with various etiopathologic factors. Management of these patients poses extreme difficulties in every procedure during prosthesis fabrication. Restricted mouth opening of the patient makes the insertion and the removal of the tray extremely difficult. So sectioning of the existing stock tray is necessary, so that the trays can be inserted and removed in sections. The main problem encountered during this procedure is the reorientation of the tray back in position. This article presents an innovative technique for the easy handling of the sectioned stock impression trays. PMID:24431708

Aswini Kumar, K; Bhat, Vinaya; Nandini, V Vidyashree; Chandrasekharan Nair, K

2013-03-01

245

[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

246

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

PubMed Central

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

Gilron, Roee; Gutchess, Angela H.

2012-01-01

247

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

248

A comparison of dimensional accuracy between three different addition cured silicone impression materials.  

PubMed

Ten impressions of a metal implant abutment were made with each of three addition-cured silicone impression materials. Using the technique of co-ordinate metrology, the shoulder region of the abutment and corresponding regions of both impressions and dies made from these impressions were scanned and measured. Comparison of these measurements indicated that the mean dimension measured from the shoulder region for each group of impression materials was significantly different from those taken from the original metal implant abutment. However, when these impressions were cast in a gypsum based die material, none of the measured dimensions taken from the casts were significantly different from those taken from the original metal implant abutment. Thus, any change in measured dimensions occurring during impression making, was compensated for in some way by the casting process. PMID:16011234

Forrester-Baker, L; Seymour, K G; Samarawickrama, D; Zou, L; Cherukara, G; Patel, M

2005-06-01

249

Elastic and Quasielastic Neutron Scattering on Liquid Isotopic and Binary Blends of Low Molecular Mass Poly(siloxanes)  

NASA Astrophysics Data System (ADS)

The effect of thermodynamic interactions on the structure and dynamics of isotopic and binary low molecular mass poly(siloxane) blends was studied by means of small angle neutron scattering and neutron spin echo spectroscopy in the macroscopically homogenous regime. It was found that the Rouse dynamics becomes governed by spatial restrictions, if the correlation length of the compositional fluctuations is comparable to the size of the individual polymer chains. The experimental findings fit to the model of droplet formation and chain localisation.

Ewen, B.; Götz, H.; Maschke, U.

250

Accuracy of five implant impression technique: effect of splinting materials and methods  

PubMed Central

PURPOSE The aim of this study was to evaluate the effect of dimensional stability of splinting material on the accuracy of master casts. MATERIALS AND METHODS A stainless steel metal model with 6 implants embedded was used as a master model. Implant level impressions were made after square impression copings were splinted using 5 different techniques as follows. (1) Splinted with autopolymerizing resin and sectioned, reconnected to compensate polymerization shrinkage before the impression procedure. (2) Splinted with autopolymerizing resin just before impression procedure. (3) Primary impression made with impression plaster and secondary impression were made over with polyether impression material. (4) Splinted with impression plaster. (5) Splinted with VPS bite registration material. From master model, 5 impressions and 5 experimental casts, total 25 casts were made for each of 5 splinting methods. The distortion values of each splinting methods were measured using coordinate measuring machine, capable of recordings in the x-, y-, z-axes. A one-way analysis of variance (ANOVA) at a confidence level of 95% was used to evaluate the data and Tukey's studentized range test was used to determine significant differences between the groups. RESULTS Group 1 showed best accuracy followed by Group 3 & 4. Group 2 and 5 showed relatively larger distortion value than other groups. No significant difference was found between group 3, 4, 5 in x-axis, group 2, 3, 4 in y-axis and group 1, 3, 4, 5 in z-axis (P<.0001). CONCLUSION Both Splinting impression copings with autopolymerizing resin following compensation of polymerization shrinkage and splinting method with impression plaster can enhance the accuracy of master cast and impression plaster can be used simple and effective splinting material for implant impression procedure. PMID:22259700

Cho, Sung-Bum

2011-01-01

251

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

SciTech Connect

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

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

2005-02-03

252

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

SciTech Connect

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

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

2004-11-29

253

Lateral Orbitofrontal Cortex Involvement in Initial Negative Aesthetic Impression Formation  

PubMed Central

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

Munar, Enric; Nadal, Marcos; Rossello, Jaume; Flexas, Albert; Moratti, Stephan; Maestu, Fernando; Marty, Gisele; Cela-Conde, Camilo J.

2012-01-01

254

Memristive learning and memory functions in polyvinyl alcohol polymer memristors  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

255

Phonon transport in an initially twisted polyvinyl acetate nanofiber  

NASA Astrophysics Data System (ADS)

A reduction in phonon thermal conductivity enhances thermoelectric performance. One method to accomplish this is by applying mechanical stress to a nanostructure. We consider an initially twisted 20 nm polyvinyl acetate nanofiber undergoing torsion. Our analytical method uses the continuum approach of Mooney's model. Torsion modifies the phonon dispersion. Angles of twist between 45° and 70° reduce the averaged phonon group velocity and the phonon thermal conductivity but when these angles are increased further, this conductivity increases. This suggests a phonon engineering approach to tune the thermal conductivity of nanomaterials.

Liangruksa, Monrudee; Puri, Ishwar K.

2013-05-01

256

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

257

Corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments  

NASA Astrophysics Data System (ADS)

The objective of this study is to evaluate corrosion resistance and durability of siloxane ceramic/polymer films for aluminum alloys in marine environments. Al5052-H3 and Al6061-T6 were selected as substrates, and HCLCoat11 and HCLCoat13 developed in the Hawaii Corrosion Laboratory were selected for the siloxane ceramic/polymer coatings. The HCLCoat11 is a quasi-ceramic coating that has little to no hydrocarbons in its structure. The HCLCoat13 is formulated to incorporate more hydrocarbons to improve adhesion to substrate surfaces with less active functionalities. In this study, two major corrosion evaluation methods were used, which were the polarization test and the immersion test. The polarization tests provided theoretical corrosion rates (mg/dm 2/day) of bare, HCLCoat11-coated, and HCLCoat13-coated aluminum alloys in aerated 3.15wt% sodium chloride solution. From these results, the HCLCoat13-coated Al5052-H3 was found to have the lowest corrosion rate which was 0.073mdd. The next lowest corrosion rate was 0.166mdd of the HCLCoat11-coated Al5052-H3. Corrosion initiation was found to occur at preexisting breaches (pores) in the films by optical microscopy and SEM analysis. The HCLCoat11 film had many preexisting breaches of 1-2microm in diameter, while the HCLCoat13 film had much fewer preexisting breaches of less than 1microm in diameter. However, the immersion tests showed that the seawater immersion made HCLCoat13 film break away while the HCLCoat11 film did not apparently degrade, indicating that the HCLCoat11 film is more durable against seawater than the HCLCoat13. Raman spectroscopy revealed that there was some degradation of HCLCoat11 and HCLCoat13. For the HCLCoat11 film, the structure relaxation of Si-O-Si linkages was observed. On the other hand, seawater generated C-H-S bonds in the HCLCoat13 film resulting in the degradation of the film. In addition, it was found that the HCLCoat11 coating had anti-fouling properties due to its high water contact angle. As candidate materials for a marine construction (e.g. the heat exchangers for ocean thermal energy conversion (OTEC) plants), the HCLCoat11-coated Al5052-H3 proved to be a durable, corrosion resistant combination with anti-fouling characteristics.

Kusada, Kentaro

258

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

259

Polystyrene Size Determination in Polystyrene and Poly(vinyl methyl ether) Using Electronic Excitation Transport  

E-print Network

Polystyrene Size Determination in Polystyrene and Poly(vinyl methyl ether) Using Electronic, polystyrene and poly(vinyl methyl ether). In the polystyrene host, measurement of the electronic excitation a compatible polymer blend with polystyrene. Analysis of r(t) data shows that the radius of gyration

Fayer, Michael D.

260

Adsorption of Sodium Dodecyl Sulfate and Sodium Dodecyl Benzenesulfonate on Poly(Vinyl Chloride) Latexes  

E-print Network

1 Adsorption of Sodium Dodecyl Sulfate and Sodium Dodecyl Benzenesulfonate on Poly(Vinyl Chloride@cpe.fr #12;2 Abstract The adsorption of sodium dodecyl sulfate (SDS) and sodium dodecyl benzenesulfonate (SDBS) on poly(vinyl chloride) (PVC) latex particles was investigated. Conductometric titrations were

Paris-Sud XI, Université de

261

Research paper Diffusional characteristics of freeze/thawed poly(vinyl alcohol) hydrogels  

E-print Network

The incorporation of a model protein, bovine serum albumin (BSA), into poly(vinyl alcohol) (PVA) hydrogel ®lms(vinyl alcohol); Freezing/thawing process; Bovine serum albumin; Laminate 1. Introduction Poly(vinyl alcohol found to be capable of initi- ally fast release rates of a model protein, bovine serum albumin (BSA

Peppas, Nicholas A.

262

A potassium-ion selective electrode with valinomycin based poly(vinyl chloride) membrane and a poly(vinyl ferrocene) solid contact  

Microsoft Academic Search

The construction of an ion-selective electrode for potassium, employing valinomycin as carrier in a poly(vinyl chloride) membrane and a poly(vinyl ferrocene) solid contact between the membrane and the metallic substrate, is described. The performance of this electrode is compared to electrodes in the coated-wire configuration and the conventional electrode with an aqueous internal reference electrolyte. Nernstian responses were obtained for

Peter C. Hauser; David W. L. Chiang; Graham A. Wright

1995-01-01

263

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

264

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

265

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

266

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.

267

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

PubMed

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™. PMID:21832720

Wang, Zu-Yong; Zhao, Yang; Ren, Lei; Jin, Li-Hua; Sun, Li-Ping; Yin, Pei; Zhang, Ya-Fei; Zhang, Qi-Qing

2008-11-01

268

Inhibition of Candida albicans biofilm formation by antimycotics released from modified polydimethyl siloxane.  

PubMed

Unlike various disinfectants, antifungals have not been commonly incorporated so far in medical devices, such as catheters or prostheses, to prevent biofilm formation by Candida spp. In the present study, five antimycotics were added to polydimethyl siloxane (PDMS) disks via admixture (nystatin) or impregnation (trimethylsilyl-nystatin (TMS-nystatin), miconazole, tea tree oil (TTO), zinc pyrithione). Nystatin-medicated PDMS disks exhibited a concentration-dependent inhibitory effect on biofilm formation in a microtiter plate (MTP) but not in a Modified Robbins Device (MRD). This observation, together with HPLC data and agar diffusion tests, indicates that a small fraction of free nystatin is released, which kills Candida albicans cells in the limited volume of a MTP well. In contrast, biofilm inhibition amounted to more than one log unit in the MRD on disks impregnated with miconazole, TTO, and zinc pyrithione. It is hypothesized that the reduction in biofilm formation by these compounds in a flow system occurs through a contact-dependent effect. PMID:19774486

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

2010-03-01

269

Nonfunctionalized Polydimethyl Siloxane Superhydrophobic Surfaces Based on Hydrophobic-Hydrophilic Interactions  

SciTech Connect

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

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

2011-01-01

270

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

271

Neuro-impressions: interpreting the nature of human creativity  

PubMed Central

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

Siler, Todd Lael

2012-01-01

272

Efficacy of various spray disinfectants on irreversible hydrocolloid impressions.  

PubMed

This study evaluated the effectiveness of eight disinfectant sprays on irreversible hydrocolloid impressions contaminated with three microorganisms (Staphylococcus aureus, Mycobacterium phlei, or Bacillus subtilis) or mixed oral flora. Alcide LD, OMC II, Biocide, and Professional Lysol Spray were relatively ineffective under the test conditions. Sporicidin and 0.525% sodium hypochlorite were able to effect a 4-log10 (99.99%) reduction against S aureus only. A 4-log10 reduction in bacterial counts was achieved by 5.25% sodium hypochlorite and Impresept in all tests except against B subtilis. Full-strength sodium hypochlorite (5.25%) was the most effective disinfectant overall and required the shortest contact time. PMID:1520443

Westerholm, H S; Bradley, D V; Schwartz, R S

1992-01-01

273

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

274

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

PubMed Central

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

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

2014-01-01

275

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

276

Insular and hippocampal contributions to remembering people with an impression of bad personality.  

PubMed

Our impressions of other people are formed mainly from the two possible factors of facial attractiveness and trustworthiness. Previous studies have shown the importance of orbitofrontal-hippocampal interactions in the better remembering of attractive faces, and psychological data have indicated that faces giving an impression of untrustworthiness are remembered more accurately than those giving an impression of trustworthiness. However, the neural mechanisms of the latter effect are largely unknown. To investigate this issue, we investigated neural activities with event-related fMRI while the female participants rated their impressions of the personalities of men in terms of trustworthiness. After the rating, memory for faces was tested to identify successful encoding activity. As expected, faces that gave bad impressions were remembered better than those that gave neutral or good impressions. In fMRI data, right insular activity reflected an increasing function of bad impressions, and bilateral hippocampal activities predicted subsequent memory success. Additionally, correlation between these insular and hippocampal regions was significant only in the encoding of faces associated with a bad impression. Better memory for faces associated with an impression of bad personality could reflect greater interaction between the avoidance-related insular region and the encoding-related hippocampal region. PMID:22349799

Tsukiura, Takashi; Shigemune, Yayoi; Nouchi, Rui; Kambara, Toshimune; Kawashima, Ryuta

2013-06-01

277

Properties of a new polyether urethane dimethacrylate photoinitiated elastomeric impression material.  

PubMed

The photoinitiated impression material is supplied premixed as a light-bodied material in a light-tight plastic syringe and as a heavy-bodied material in a tube. The impression material has excellent physical, mechanical, and clinical qualities with noteworthy long working times, short setting times, dimensional stability, accuracy, high tear strength, good wettability, biocompatibility, and ease of cold disinfection without loss of quality. The impression material is also compatible with gypsum and silver or copper metallizing baths. Accurate casts can be obtained by means of either a double-impression technique or a double-mix technique. PMID:2295985

Craig, R G; Hare, P H

1990-01-01

278

Evaluation of a Polyvinyl Toluene Neutron Counter Array  

SciTech Connect

The purpose of this article is to simulate the performance of a neutron detector array for empirical configuration optimization and preliminary algorithm evaluation. Utilizing a compact array of borated Polyvinyl Toluene light pipes and Photomultiplier Tubes, pulse shape analysis, standard spectral histogramming, and multiplicity counting can enable neutron measurements for multiple applications. Results demonstrate that analysis with Monte Carlo N-Particle (MCNP) can be used to obtain a better understanding of field measurement results and aid in algorithm development for unfolding in conjunction with detector optimization. Use of a handheld neutron spectrometer has promise of widespread applicability. By correlating MCNP results with empirical measurements, substantial confidence can be placed on predicting detector response to sufficiently similar spectral sources under alternate experimental configurations. In addition, use of the detector has substantial promise for operational health physics applications.

Robert Hayes

2008-03-01

279

Evaluation of vascular grafts based on polyvinyl alcohol cryogels.  

PubMed

The present study designed and developed blood vessel substitutes (BVSs) composed of polyvinyl alcohol (PVA) cryogels. The in vitro results demonstrated that the coating of the polymer with lyophilized decellularized vascular matrix (DVM) greatly enhanced the adhesion of human umbilical vein endothelial cells (HUVECs). However, when PVA?DVM BVSs were implanted into the abdominal aorta of Sprague?Dawley rats, DVM was identified as a highly thrombogenic surface resulting in the mortality of all animals 3?4 days after surgery. By contrast, all rats implanted with PVA survived and were sacrificed after 12 months. The luminal surface of the explanted grafts was completely covered by endothelial cells and the inner diameter was similar to that of the original vessel. In conclusion, the present study indicated that PVA may be considered as a promising biomaterial for the fabrication of artificial vessels. PMID:24969541

Conconi, Maria Teresa; Borgio, Luca; Di Liddo, Rosa; Sartore, Leonardo; Dalzoppo, Daniele; Amistà, Pietro; Lora, Silvano; Parnigotto, Pier Paolo; Grandi, Claudio

2014-09-01

280

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

281

Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

282

Cross-linked polyvinyl alcohol films as alkaline battery separators  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

283

Cross-linked polyvinyl alcohol films as alkaline battery separators  

NASA Technical Reports Server (NTRS)

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

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

1983-01-01

284

Growth characteristics of selected fungi on polyvinyl chloride film.  

PubMed Central

The objective of this study was to determine if plasticized polyvinyl chloride film would support the growth of any of nine species of fungi. The film was suspended in distilled water with no nutrients or with glucose or ammonium sulfate. Spores of each of the test species were inoculated into the suspension medium, and the mixture was incubated at 30 degrees C for up to 18 weeks. Most species were found to be capable of utilizing the film for carbon or nitrogen when the other nutrient was supplied. Only two species, Aspergillus fischeri and Paecilomyces sp., were found to be capable of utilizing components of the film without added nutrients. Components of the polyvinyl chloride film were then incorporated into mineral salts medium to determine if these components could serve as carbon sources in the presence of ammonium nitrate. The only component found to be utilized by all the fungi as a carbon source was epoxidized oil, a plasticizer-stabilizer. Calcium-zinc stearate was an available carbon source for all except the Penicillium and Verticillium strains. The only other component utilized was a stearamide, which was metabolized solely by the Aspergillus sp. Only the stearamide contained enough nitrogen to serve as a primary source in the film. The compound, however, did not support growth of fungi in the presence of glucose. It was theorized that either the nitrogen of the stearamide was more readily available to the fungi in the whole film due to the presence of trace nutrients or the nitrogen was supplied by exogenous sources. PMID:3707118

Roberts, W T; Davidson, P M

1986-01-01

285

In situ self cross-linking of polyvinyl alcohol battery separators  

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

286

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

287

Survey of prosthodontic impression procedures for complete dentures in general dental practice in the United Kingdom  

Microsoft Academic Search

Statement of problem. Anecdotal evidence suggests impression techniques used in general dental practice may vary from those taught at dental schools. There is little published information on this topic. Purpose. This study identifies the materials and methods used by general dental practitioners for recording impressions for the provision of replacement of complete dentures. Methods. A total of 905 questionnaires were

T. Paul Hyde; J. Fraser McCord

1999-01-01

288

Impression Management and Leadership Emergence in Virtual Settings:The Role of Gender and Media  

Microsoft Academic Search

This paper describes a theoretical model that articulates how members of virtual teams engage in various impression management behaviors to influence their peers' assessment of them as leaders. Given that previous research has indicated that men and women engage in different impression management behaviors and that settings differ with respect to the degree of technological capabilities, our model includes these

JoAnne Yong-Kwan Lim

2008-01-01

289

Accurate 3D Footwear Impression Recovery From Photographs Fernanda A. Andalo  

E-print Network

Forensics, Footwear impression recovery, Shoe print, Multiview stereo. Abstract The recovery of footwear- evant to the investigation ­ which include DNA, tire tracks, fingerprints, shoe prints, bloodstains using different forensic techniques. Plastic or 3D footwear impressions have depth in addition to length

Taubin, Gabriel

290

Teaching: First Impressions First, or Choosing Atmosphere over Method and Management  

ERIC Educational Resources Information Center

As a writer who teaches and a teacher who writes, this author offers creative ways of producing a positive first impression on the first day of school. The key is finding a way to surprise one's students and creating first impressions that somehow introduces the tone a teacher wants his or her class to have. The author has learned that if he can…

Levy, Aaron

2004-01-01

291

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

292

Use of footwear impressions in crime scene investigations assisted by computerised footwear collection system  

Microsoft Academic Search

Crime scene footwear classification systems can be utilized to look for possible suspects, to get models and brand names for crime scene impressions and to link crime scenes. In this work a computerised footwear classification system is presented. The classification coding of the system has been designed especially for partial footwear impressions which are the most typical in crime scenes.

Sirkka Mikkonen; Vesa Suominen; Pia Heinonen

1996-01-01

293

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. PMID:23276216

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

2014-01-01

294

Getting at the truth or getting along: Accuracy versus impression-motivated heuristic and systematic processing  

Microsoft Academic Search

Two studies examined the heuristic and systematic processing of accuracy- versus impression-moti- vated individuals expecting a discussion with a partner believed to hold either a favorable or unfa- vorable opinion on the discussion issue. Given the goal of having a pleasant interaction, impression- motivated (versus accuracy-motivated) participants in both studies were particularly likely to ex- press attitudes that were evaluatively

Serena Chen; David Shechter; Shelly Chaiken

1996-01-01

295

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

296

Try to find me: social anxiety and peer first impressions.  

PubMed

Following initial interactions, some people are less willing to pursue ongoing contact with socially anxious individuals than with those who are not socially anxious. To better understand this process, we conducted two studies that examined peers' first impressions of target individuals. Unacquainted individuals (N=104 and 114) participated in round robin, unstructured interactions in groups of 3 to 10 and then rated each partner and themselves on items reflecting the Big Five personality dimensions. The ratings were analyzed according to Biesanz's (2010) social accuracy model of interpersonal perception, which distinguishes the positivity from the accuracy of social judgments. Study 1 revealed that perceivers did not view socially anxious targets more negatively or as less likable than non-socially anxious targets but were less able to recognize their unique personality features. Study 2 replicated those findings and indicated that perceivers' difficulties recognizing socially anxious targets' unique features were not due to negative biases in the socially anxious targets' self-ratings or to general psychological maladjustment. The findings are consistent with cognitive models, which underscore the role of self-concealment in social anxiety disorder. PMID:25311293

Aiken, Audrey; Human, Lauren J; Alden, Lynn E; Biesanz, Jeremy C

2014-11-01

297

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. PMID:24959520

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

2014-01-01

298

Capturing finger and palm impressions using a hand cream and thermochromatic paper.  

PubMed

An inkless set of finger and palm impressions has been obtained on thermochromatic paper by incorporating the protic solvent butylene glycol into a base hand cream mixture, which is rubbed into the hands for 30 sec before donation. This requires no washing of the hands before or after donation, removing many of the difficulties associated with inked impressions. In a random trial of 50 male and 50 female participants (mean age 41 years), 96 found the hand cream pleasant and easy to use and all produced identifiable finger and palm impressions. Following donation, participants continued to rub the hand cream into their hands. Impressions were visible immediately after donation and have not exhibited fading 2 years after being taken. 10% of participants produced impressions that captured third-level detail, the variation between participants being thought to be associated with the amount of pressure applied during donation. PMID:23865966

Bond, John W

2013-09-01

299

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

300

White light scanner-based repeatability of 3-dimensional digitizing of silicon rubber abutment teeth impressions  

PubMed Central

PURPOSE The aim of this study was to evaluate the repeatability of the digitizing of silicon rubber impressions of abutment teeth by using a white light scanner and compare differences in repeatability between different abutment teeth types. MATERIALS AND METHODS Silicon rubber impressions of a canine, premolar, and molar tooth were each digitized 8 times using a white light scanner, and 3D surface models were created using the point clouds. The size of any discrepancy between each model and the corresponding reference tooth were measured, and the distribution of these values was analyzed by an inspection software (PowerInspect 2012, Delcamplc., Birmingham, UK). Absolute values of discrepancies were analyzed by the Kruskal-Wallis test and multiple comparisons (?=.05). RESULTS The discrepancy between the impressions for the canine, premolar, and molar teeth were 6.3 µm (95% confidence interval [CI], 5.4-7.2), 6.4 µm (95% CI, 5.3-7.6), and 8.9 µm (95% CI, 8.2-9.5), respectively. The discrepancy of the molar tooth impression was significantly higher than that of other tooth types. The largest variation (as mean [SD]) in discrepancies was seen in the premolar tooth impression scans: 26.7 µm (95% CI, 19.7-33.8); followed by canine and molar teeth impressions, 16.3 µm (95% CI, 15.3-17.3), and 14.0 µm (95% CI, 12.3-15.7), respectively. CONCLUSION The repeatability of the digitizing abutment teeth's silicon rubber impressions by using a white light scanner was improved compared to that with a laser scanner, showing only a low mean discrepancy between 6.3 µm and 8.9 µm, which was in an clinically acceptable range. Premolar impression with a long and narrow shape showed a significantly larger discrepancy than canine and molar impressions. Further work is needed to increase the digitizing performance of the white light scanner for deep and slender impressions. PMID:24353885

Jeon, Jin-Hun; Lee, Kyung-Tak; Kim, Hae-Young; Kim, Ji-Hwan

2013-01-01

301

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

E-print Network

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

Sample, Caitlin (Caitlin Sarah)

2014-01-01

302

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

303

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

PubMed

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

Rojas Devia, Carolina; Subrenat, Albert

2013-01-01

304

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

2011-03-01

305

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

306

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 PMID:24790878

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

2014-01-01

307

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. PMID:23878566

Amalan, Arul; Ginjupalli, Kishore; Upadhya, Nagaraja

2013-01-01

308

Does aging impair first impression accuracy? Differentiating emotion recognition from complex social inferences.  

PubMed

Young adults can be surprisingly accurate at making inferences about people from their faces. Although these first impressions have important consequences for both the perceiver and the target, it remains an open question whether first impression accuracy is preserved with age. Specifically, could age differences in impressions toward others stem from age-related deficits in accurately detecting complex social cues? Research on aging and impression formation suggests that young and older adults show relative consensus in their first impressions, but it is unknown whether they differ in accuracy. It has been widely shown that aging disrupts emotion recognition accuracy, and that these impairments may predict deficits in other social judgments, such as detecting deceit. However, it is unclear whether general impression formation accuracy (e.g., emotion recognition accuracy, detecting complex social cues) relies on similar or distinct mechanisms. It is important to examine this question to evaluate how, if at all, aging might affect overall accuracy. Here, we examined whether aging impaired first impression accuracy in predicting real-world outcomes and categorizing social group membership. Specifically, we studied whether emotion recognition accuracy and age-related cognitive decline (which has been implicated in exacerbating deficits in emotion recognition) predict first impression accuracy. Our results revealed that emotion recognition accuracy did not predict first impression accuracy, nor did age-related cognitive decline impair it. These findings suggest that domains of social perception outside of emotion recognition may rely on mechanisms that are relatively unimpaired by aging. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25244469

Krendl, Anne C; Rule, Nicholas O; Ambady, Nalini

2014-09-01

309

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

310

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

PubMed Central

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

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

2014-01-01

311

The elastomers for complete denture impression: A review of the literature  

PubMed Central

This article reviews the current trends in materials used for complete denture impression. Peer-reviewed articles, published in English and in French between 1954 and 2007, were identified through a MEDLINE search (Pubmed and Elsevier) and a hand search of relevant textbooks and annual publications. Emphasis was made on the characteristics of the elastomers, their manipulation, the different techniques used, and the quality of the impression obtained. The combination of excellent physical properties, handling characteristics, and unlimited dimensional stability assures the popularity of these impression materials. PMID:24151408

Daou, Elie E.

2010-01-01

312

Compression properties of polyvinyl alcohol--bacterial cellulose nanocomposite.  

PubMed

Despite the established use of total joint replacement for the treatment of advanced degeneration of articular cartilage, component loosening due to wear and osteolysis limits the lifespan of these joint prostheses. In the present study, nanocomposites consisting of poly(vinyl alcohol) (PVA) and bacterial cellulose (BC) nanofibers were investigated as possible improved cartilage replacement materials. Nanocomposites were synthesized by adding small amounts (<1%) of BC to PVA, and subjecting the mixture to thermal cycling. The mechanical properties of the resulting material were evaluated using unconfined compression testing. By the addition of BC nanofibers to the PVA matrix, a nanocomposite with a wide range of compressive mechanical properties control was obtained, with elastic modulus values similar to those reported for native articular cartilage. The nanocomposite also showed improved strain-rate dependence and adequate viscoelastic properties. The PVA-BC nanocomposite is therefore a promising biomaterial to be considered as a possible replacement material for localized articular cartilage injuries and other orthopedic applications such as intervertebral discs. PMID:19360889

Millon, Leonardo E; Oates, Christine J; Wan, Wankei

2009-08-01

313

Oil reclamation from waste plastics including polyvinyl chloride  

SciTech Connect

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

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

1995-12-31

314

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

315

Modeling of solute sorption by polyvinyl chloride plastic infusion bags.  

PubMed

Methods for estimating the equilibrium and time-dependent sorption of solutes by polymeric containers have been developed. The methods are specifically applied to the sorption of solutes by polyvinyl chloride (PVC) infusion bags. The methods correlate the partition coefficients and dissociation constant (when appropriate) of the solute, the physical dimensions of the container, and solution pH with single parameters that dictate the shape of the sorption profile. To determine the equilibrium sorption level for PVC containers, the fractional binding of a solute is correlated with its hexane-water and octanol-water partition coefficients. Calculations based on single partition coefficients are less effective in terms of mimicking the behavior of the PVC. To determine the sorption profile (fractional binding versus time), the partition coefficients are related to the fraction binding at a particular time through a single parameter referred to as the sorption number. Equilibrium fractional binding and sorption profiles for various drugs stored in PVC containers are generated with the models and agree well with reported behavior. The effect of pH on the sorption process is also examined. PMID:8289128

Jenke, D R

1993-11-01

316

MOTIVATION AND OPPORTUNITY: THE ROLE OF REMOTE WORK, DEMOGRAPHIC DISSIMILARITY, AND SOCIAL NETWORK CENTRALITY IN IMPRESSION MANAGEMENT  

Microsoft Academic Search

This study examined relationships among remote work, demographic dissimilarity, social network centrality, and the use and effectiveness of impression management behaviors. In our findings, a higher proportion of time spent working remotely from supervisors increased the frequency of supervisor- and job-focused impression man- agement, but reduced social network centrality decreased job-focused impression management. Social network centrality moderated the relationships between

ZOE I. BARSNESS; KRISTINA A. DIEKMANN; MARC-DAVID L. SEIDEL

2005-01-01

317

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. PMID:24479892

2014-01-01

318

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

319

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

E-print Network

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

Hutchinson, John W.

320

Loud and Trendy: Crowdsourcing Impressions of Social Ambiance in Popular Urban Places  

E-print Network

There is an increasing interest in social media and ubiquitous computing to characterize places in urban spaces beyond their function and towards psychological constructs like ambiance, i.e, the impressions people form about places when they first visit them - energetic, bohemian, loud, artsy, and so on. In this paper, we study whether reliable impressions of a place's ambiance can be obtained from images shared on social media sites like Foursquare. Crowdsourcing is used to gather ambiance impressions of places using images obtained from Foursquare. The studied setting is thus similar to what social media users do to implicitly judge a place online. Using data collected from 300 popular places across six cities worldwide, we present results on data annotated on Amazon's Mechanical Turk for 13 dimensions of ambiance. We found that reliable estimates of social ambiance can be obtained from user-contributed images, suggesting the presence of strong visual cues to form accurate place impressions. Furthermore, we...

Santani, Darshan

2014-01-01

321

Direct custom implant impression copings for the preservation of the pontic receptor site architecture.  

PubMed

The direct custom implant impression coping technique is designed to record the periimplant gingiva and pontic receptor site after the tissues have been shaped with a provisional restoration. The technique prevents inaccurate recording of the gingival architecture by using a dual polymerizing composite resin placed into the sulcus and pontic receptor sites and adapted to the open tray implant impression copings. This technique may improve soft tissue accuracy between the clinical condition and the laboratory cast. PMID:22489334

Schoenbaum, Todd R; Han, Thomas J

2012-03-01

322

Comparison of occlusal contacts in maximum intercuspation for two impression techniques  

Microsoft Academic Search

Statement of problem. At the insertion of a fixed prosthesis, occlusal interferences in maximum intercuspation are often present.Purpose. This study investigated and compared the accuracy of interocclusal relationships in maximum intercuspation for mounted casts obtained from a quadrant dual-arch impression technique and conventional full-arch impression techniques.Material and methods. Comparisons were made between an intraoral interocclusal record and interocclusal records made

Merle H. Parker; Stephen M. Cameron; James C. Hughbanks; David E. Reid

1997-01-01

323

Measured effects of surface cloth impressions on polar backscatter and comparison with a reflection grating model  

NASA Technical Reports Server (NTRS)

This paper focuses on the nature of a typical composite surface and its effects on scattering. Utilizing epoxy typical of that in composites and standard composite fabrication methods, a sample with release cloth impressions on its surface is produced. A simple model for the scattering from the surface impressions of this sample is constructed and then polar backscatter measurements are made on the sample and compared with the model predictions.

Madaras, Eric I.; Brush, Edwin F., III; Bridal, S. L.; Holland, Mark R.; Miller, James G.

1992-01-01

324

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. PMID:24966729

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

2013-01-01

325

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. PMID:24653597

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

2014-01-01

326

Single Stage Silicone Border Molded Closed Mouth Impression Technique-Part II.  

PubMed

Functioning of a complete denture depends to a great extent on the impression technique. Several impression techniques have been described in the literature since the turn of this century when Greene [Clinical courses in dental prothesis, 1916] brothers introduced the first scientific system of recording dental impression. Advocates of each technique have their own claim of superiority over the other. The introduction of elastomeric impression materials [Skinner and Cooper, J Am Dent Assoc 51:523-536, 1955] has made possible new techniques of recording impression for complete denture construction. These rubber like materials are of two types; one has a polysulfide base and is popularily known as polysulfide rubber (Thiokol and Mercaptan). The other variety has a silicone base known as silicone rubber or silicone elastomer. Silicone elastomers are available in four different consistencies; a thin easy flowing light bodied material,a creamy medium bodied material, a highly viscous heavy bodied material and a kneadable putty material. This paper describes an active closed mouth impression technique with one stage border molding using putty silicone material as a substitute for low fusing compound. PMID:22942578

Solomon, E G R

2011-09-01

327

Enhanced Glucose Sensor Linearity Using Poly(Vinyl Alcohol) Hydrogels  

PubMed Central

Background High linearities, sensitivities, and low oxygen dependence constitute prime requisites for electrochemical glucose sensors. However, for implantable sensors the need to control tissue inflammation requires the use outer membranes that permit inward analyte diffusion while continuously releasing anti-inflammatory drugs and other tissue response-modifying (TRM) agents. We have shown previously that while outer membranes based on layer-by-layer (LBL) assembly enhance linearity, poly(vinyl alcohol)(PVA) hydrogels loaded with TRM-containing microspheres enable a significant reduction in tissue inflammation. This article discusses amperometric performance of glucose sensors coated with stacked LBL/PVA hydrogel outer membranes. Methods Sensors were fabricated by immobilizing glucose oxidase enzyme on a 50-?m platinum wire followed by deposition of stacked LBL/PVA hydrogel outer membranes. The sensor response to various glucose concentrations was determined by applying 0.7 V vs an Ag/AgCl reference electrode in phosphate-buffered saline (37°C). Michaelis–Menten analysis was performed to quantify sensor performance in terms of linearity (Km,gluapp) and oxygen dependence (Km,O2app/[Glucose]). Results When overlaid onto LBL-assembled outer membranes, PVA hydrogels improved sensor linearity by 60% from 10 to 16 mM of glucose and resulted in a twofold decrease in oxygen dependence. Conclusions Enhancement in the performance of a PVA-coated sensor is attributed to the oxygen-storing capability of PVA hydrogel due to the formation of hydrophobic domains during its freezing and thawing employed to physical cross-link the PVA. Such membranes with the capability to release TRMs continuously while storing oxygen constitute a major improvement over current outer membrane technologies. PMID:20144336

Vaddiraju, SanthiSagar; Singh, Hardeep; Burgess, Diane J.; Jain, Faquir C.; Papadimitrakopoulos, Fotios

2009-01-01

328

A clinical report on the use of closed-tray, hex-lock-friction-fit implant impression copings.  

PubMed

The precision of an impression determines the subsequent accuracy and fit of the final restoration. Therefore, the ultimate search is for the most accurate impression material and the most efficient and least time consuming technique. One of the major debates in implant dentistry has focused on the advantages of the pick-up versus the transfer impression technique. The pick-up technique is widely accepted as the more accurate. However, the conventional transfer technique is simpler and less time consuming. The Hex-Lock-Friction-Fit impression coping (AB Dental Devices) combines the advantages of the transfer impression technique and the pick-up impression technique. In this article we will review the relevant literature, discuss the advantages of this unique implant impression technique, and present some related clinical cases. PMID:25106009

Raviv, Eli; Hanna, Jan; Raviv, Roy; Harel-Raviv, Mili

2014-08-01

329

Endothelial cell response to polyvinyl chloride-packaged GORETEX: effect of surface contamination.  

PubMed

A Fourier transform infrared spectroscopic study of polyvinyl chloride packaged GORETEX vascular prostheses indicated that their internal and external surfaces were coated with an additive layer presumed to be derived from the polyvinyl chloride packaging. This layer was not removed by washing in phosphate buffered saline but was soluble in trimethyl pentane and hexane. Some other treatments of GORETEX and the packaging were shown to remove the contaminant from the surface and this correlated with an inferior in vitro aortic endothelial cell response. Analyses of materials extracted from both the polyvinyl chloride and the GORETEX surface indicated that the major surface component was a long chain aliphatic ester, either a plasticizer or a lubricant constituent. PMID:2302453

Hodgkin, J H; Heath, G R; Norris, W D; Donald, G S; Johnson, G

1990-01-01

330

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

E-print Network

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

Van de Ven, James D.

331

Multiple-hologram storage for thin layers of Methyl Orange dyes in polyvinyl alcohol matrices  

NASA Astrophysics Data System (ADS)

We realized hologram storage within a 0.07-cm2 light spot in thin layers of polyvinyl alcohol matrices doped with Methyl Orange dyes preirradiated by the 488.0-nm line of an Ar-ion laser with two orthogonal linearly polarized 632.8-nm light beams. By rotation of the sample, multiple-hologram storage was achieved. By controlling the writing time, we have recorded three-hologram and five-hologram images in the same light spot. The mechanism of the multiple-hologram storage in Methyl Orange-doped polyvinyl alcohol thin films is discussed.

Liu, Yichun; Wang, Haiyu; Tian, Mingzhen; Lin, Jiulin; Kong, Xianggui; Huang, Shihua; Yu, Jiaqi

1995-07-01

332

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

SciTech Connect

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

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

1999-05-19

333

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

PubMed Central

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 Simoes; Benetti, Ana Raquel

2011-01-01

334

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

PubMed Central

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

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

2013-01-01

335

Sequence discrimination of heterogeneous crossing of seal impression and ink-printed text using adhesive tapes.  

PubMed

This paper presents a technique to discriminate the sequence of stamped seal impression and ink-printed text in a document to detect falsely signed documents. In many Asian countries where a seal is widely used to endorse documents, a possibly forged document involves a seal impressed before the text is printed. The proposed method uses adhesive tapes with peel adhesion strength of approximately 25 oz/in. to exfoliate the top layer of the overlapping region of seal impression and ink-printed text in the document. A pair of digital images of the overlapping region, captured using an infinite focus microscope, is compared for color changes before and after the exfoliation with adhesive tapes. The proposed sequence discrimination index (SDI) measures the amount of color changes before and after the exfoliation to determine the sequence of seal impression and printed text. Experiment results show that the SDI successfully discriminates the sequence of seal impression and printed text for different types of ink cartridges and seal inkpads under various storage conditions, enabling forensic investigation of falsely signed documents with a seal. PMID:24378311

Lee, Ka Young; Lee, Joong; Kong, Seong G; Kim, Byounghyun

2014-01-01

336

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

337

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

PubMed Central

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

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

2013-01-01

338

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

PubMed

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

McAleer, Phil; Todorov, Alexander; Belin, Pascal

2014-01-01

339

Kinetic analysis of the thermo-oxidative degradation of poly(vinyl chloride) in poly(vinyl chloride)\\/methyl methacrylate-butadiene-styrene blends1 Isothermal degradation  

Microsoft Academic Search

The thermal degradation of poly(vinyl chloride)\\/poly(methyl methacrylate-butadiene-styrene) (PVC\\/MBS) blends was investigated by means of isothermal thermogravimetry in air. During 120 min the main process in the blends is the dehydrochlorination of PVC. The reaction rate constants were determined by applying the Prout–Tompkins model, which assumes autocatalytic degradation. Their values are about three times higher in air than in nitrogen. MBS

Branka Andri?i?; Tonka Kova?i?; Ivka Klari?

2002-01-01

340

High performance ultrafiltration composite membranes based on poly(vinyl alcohol) hydrogel coating on crosslinked nanofibrous poly(vinyl alcohol) scaffold  

Microsoft Academic Search

A new kind of high flux ultrafiltration (UF) membrane based on poly(vinyl alcohol) (PVA) electrospun nanofibrous scaffold support and PVA hydrogel coating has been demonstrated. The long-term performance of such membranes was optimized by a variation of degree of hydrolysis (i.e. 88–99%) and molecular weight (e.g. 13,000–124,000g\\/mol) in the electrospun PVA scaffold in conjunction with chemical crosslinking of PVA hydrogel

Xuefen Wang; Dufei Fang; Kyunghwan Yoon; Benjamin S. Hsiao; Benjamin Chu

2006-01-01

341

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

NASA Astrophysics Data System (ADS)

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

Aoki, Yusuke; Kubo, Hidenori; Shindou, Takuya

342

Physical properties and compatibility with dental stones of current alginate impression materials.  

PubMed

This study examined physical properties and compatibility with dental stones of two types of alginate impression materials. Five powder-type alginate impression materials (Alginoplast EM, Aroma Fine, Algiace Z, Coe Alginate, Jeltrate Plus) and a paste-type alginate impression material (Tokuso AP-1) were used. The dynamic viscosity immediately after mixing was measured by means of a controlled-stress rheometer. The gelation times were determined according to Japanese Industrial Standards (JIS) T6505, and recovery from deformation, strain in compression and compressive strength were determined according to the International Organization for Standardization (ISO) specification 1563. Detail reproduction and surface roughness of type III dental stones (New Plastone, New Sunstone) and a type IV dental stone (Die Stone) were evaluated using a ruled test block as specified in the ISO specification 1563 and a profilometer, respectively. The alginate impression materials evaluated in this study were all in compliance with the ISO specification 1563 and JIS T6505. The alginate impression materials had similar mechanical properties after gelation, whilst a wide range of dynamic viscosity immediately after being mixed, gelation times and compatibility with dental stones were found among the materials. The paste-type material had a higher dynamic viscosity and a shorter gelation time than the powder-type materials. The best surface quality was obtained with the paste-type material/type III dental stone cast combinations. The materials should be selected in consideration of initial flow, setting characteristics and compatibility with dental stones. The results suggested that a paste-type material would better meet the requirements of an alginate impression material. PMID:15525391

Murata, H; Kawamura, M; Hamada, T; Chimori, H; Nikawa, H

2004-11-01

343

Case report: impression and maxillo-mandibular relationship recording for construction of obturator prostheses.  

PubMed

The present case report describes a procedure for obtaining the master impression and the maxillo-mandibular relationship for the definitive prosthesis in a maxillectomy patient. After casting the metal framework, a visible-light-cured tray resin was spread over the resin retention grid and gradually cured. Modelling compound was extended over the resin with functional movements, and finally the margins of the defect were sealed with a dental impression wax. A column of light-cured resin was constructed from the lower face of the resin/compound/wax structure to the opposing dental arch. This column permitted recording of the maxillo-mandibular relationship. PMID:11695135

Dominguez, L da S; Rilo Pousa, B; Fernandez Varela, J; Martinez Insua, A

2001-03-01

344

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

345

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

346

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

NASA Astrophysics Data System (ADS)

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

Fukumoto, Makoto; Okamatsu, Keita; Matsuo, Kazuhisa

347

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

Microsoft Academic Search

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

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

2009-01-01

348

Improvement of the water resistance of poly(vinyl acetate) emulsion wood adhesive  

Microsoft Academic Search

Four different approaches were taken to improve the water resistance of poly(vinyl acetate) (PVAc) emulsion adhesives. The improved wood adhesives were tested according to the ISO 9020 standard. Tensile storage modulus (E’) and glass transition temperature of the polymer films were measured using dynamic mechanical thermal analysis to quantify the influence of different approaches on those variables. Gel fraction and

Lijun Qiao; Allan J. Easteal; Clive J. Bolt; Philip K. Coveny; Robert A. Franich

2000-01-01

349

Effects of adding nano-clay on performance of polyvinyl acetate (PVA) as a wood adhesive  

Microsoft Academic Search

Polyvinyl acetate (PVA), a thermoplastic polymer, has poor performance at elevated temperatures and humid conditions as a wood adhesive. Two types of hydrophilic nano-clay were mixed at different loadings (1%, 2% and 4%) with PVA to improve the performance of PVA towards water and elevated temperatures. The properties of PVA-clay nanocomposites were characterized by measuring the shear strength of wood

Alireza Kaboorani; Bernard Riedl

2011-01-01

350

Antibacterial surfaces by adsorptive binding of polyvinyl-sulphonate-stabilized silver nanoparticles  

Microsoft Academic Search

This paper presents a novel and facile method for the generation of efficient antibacterial coatings which can be applied to practically any type of substrate. Silver nanoparticles were stabilized with an adsorbed surface layer of polyvinyl sulphonate (PVS). This steric layer provided excellent colloidal stability, preventing aggregation over periods of months. PVS-coated silver nanoparticles were bound onto amine-containing surfaces, here

Krasimir Vasilev; Vasu R. Sah; Renee V. Goreham; Chi Ndi; Robert D. Short; Hans J. Griesser

2010-01-01

351

Pregnancy Following Uterine Artery Embolization with Polyvinyl Alcohol Particles for Patients with Uterine Fibroid or Adenomyosis  

Microsoft Academic Search

Purpose: To determine whether uterine fibroid embolization (UFE) with polyvinyl alcohol (PVA) particles affects fertility in women desiring future pregnancy. Methods: Of 288 patients managed with UFE with PVA particles for uterine myoma or adenomyosis between 1998 and 2001, 94 patients were enrolled in this study. The age range of participants was 20–40 years. The data were collected through review

Man Deuk Kim; Nahk Keun Kim; Hee Jin Kim; Mee Hwa Lee

2005-01-01

352

Intracellular proliferation of Legionella pneumophila in Hartmannella vermiformis in aquatic biofilms grown on plasticized polyvinyl chloride  

Microsoft Academic Search

The need for protozoa for the proliferation of Legionella pneumophila in aquatic habitats is still not fully understood and is even questioned by some investigators. This study shows the in vivo growth of L. pneumophila in protozoa in aquatic biofilms developing at high concentrations on plasticized polyvinyl chloride in a batch system with autoclaved tap water. The inoculum, a mixed

Melanie W. Kuiper; Bart A. Wullings; Antoon D. L. Akkermans; Rijkelt R. Beumer; Dick van der Kooij

2004-01-01

353

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

SciTech Connect

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

Oji, L.N.

1998-11-25

354

ORIGINAL PAPER Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect  

E-print Network

Science+Business Media, LLC 2008 Abstract Poly(vinyl chloride) (PVC) and natural fiber composites were of the composites. The addition of fiber to PVC matrix increased glass transi- tion temperature (Tg), but lowered, PVC/rice husk compos- ites presented relatively smaller water absorption (WA) and thickness swelling

355

Characterization of Poly(Vinyl Chloride) Aged in a Bromine Containing Electrolyte.  

National Technical Information Service (NTIS)

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

C. Arnold, A. Leo, M. Tarjani

1988-01-01

356

Nonlinear-optical properties of a poly(vinyl alcohol)-polyaniline interpenetrating polymer network  

NASA Astrophysics Data System (ADS)

The nonlinear-optical properties of a semi-interpenetrating polymer network of poly(vinyl alcohol) glutaraldehyde-polyaniline were studied. Large ( 10-12 cm2 / W) and fast ( < 50 ps) refractive optical nonlinearites were observed. The potential of this novel material for photonic applications is evaluated.

Petrov, D. V.; Gomes, A. S. L.; de Araújo, Cid B.; de Souza, J. M.; de Azevedo, W. M.; de Melo, J. V.; Diniz, F. B.

1995-03-01

357

Silastic molding method for pectus excavatum correction using a polyvinyl alcohol (ivalon) sponge.  

PubMed

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

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

2012-12-01

358

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

Microsoft Academic Search

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

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

2003-01-01

359

Amino acid metabolism of preimplantation bovine embryos cultured with bovine serum albumin or polyvinyl alcohol  

Microsoft Academic Search

Bovine serum albumin (BSA) is an embryotrophic macromolecule used in embryo culture media, which is commonly replaced with synthetic compounds, such as polyvinyl alcohol (PVA). This study compared the effect of BSA and PVA on the development, blastocyst cell number and amino acid metabolism of preimplantation bovine embryos in vitro. Embryos were produced by in vitro maturation and fertilization of

Nicolas M Orsi; Henry J Leese

2004-01-01

360

40 CFR 61.64 - Emission standard for polyvinyl chloride plants.  

...there is to be no discharge to the atmosphere from any manual vent valve on a polyvinyl...valve discharge means a discharge to the atmosphere which could not have been avoided by...Within 10 days of any discharge to the atmosphere from any manual vent valve,...

2014-07-01

361

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

SciTech Connect

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

Oji, L.N.

2000-01-04

362

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

PubMed

After viewing short video clips of individuals with Parkinson's disease (PD) who varied in the symptoms of facial masking (reduced expressivity) and abnormal bodily movement (ABM: including tremor and related movement disorders), older adult observers provided their first impressions of targets' social positivity. Impressions of targets with higher masking or ABM were more negative than impressions of targets with lower masking or ABM. Furthermore, masking was more detrimental for impressions of women and when observers considered emotional relationship goals, whereas ABM was more detrimental for instrumental relationship goals. This study demonstrated the stigmatizing effects of both reduced and excessive movement. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25244472

Hemmesch, Amanda R

2014-09-01

363

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

PubMed

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

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

2013-09-01

364

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

PubMed

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

Li, Yunhui; Zhang, Weijiang; Xu, Jiao

2014-06-30

365

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

PubMed

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

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

2014-07-21

366

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

PubMed

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

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

2013-12-17

367

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

ERIC Educational Resources Information Center

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

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

2009-01-01

368

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

369

Evaluation of the occlusal contact of crowns fabricated with the bite impression method.  

PubMed

In prosthodontic treatment, reconstruction of a proper occlusal contact relationship is very important as well as reconstruction of a proper interproximal relationship and marginal fitness. Unfortunately, occlusal relationships are sometimes lost in the process of occlusal adjustment of crowns. The purpose of this study was to compare the occlusal contacts of single crown fabricated by two different types of impression techniques. Nine subjects, whose molars required treatment with crown restoration, were enrolled in this study. Full cast crowns were fabricated using two types of impression techniques: the conventional impression method (CIM) and the bite impression method (BIM). The occlusal contacts of crowns were precisely evaluated at the following stages: after occlusal adjustment on the articulator (Step 0), before occlusal adjustment in the mouth (Step 1), after occlusal adjustment at the intercuspal position (Step 2), and after occlusal adjustment during lateral and protrusive excursions (Step 3). The number of occlusal contacts of the crowns on the functional cusps fabricated with BIM was significantly greater than that with CIM after occlusal adjustment. For this reason, the crowns fabricated with BIM might have a more functionally desirable occlusal surface compared to the crowns fabricated with CIM. PMID:24146169

Makino, Sachi; Okada, Daizo; Shin, Chiharu; Ogura, Reiko; Ikeda, Masaomi; Miura, Hiroyuki

2013-01-01

370

What the Public Thinks about Public Relations: An Impression Management Experiment.  

ERIC Educational Resources Information Center

Notes that perceived motives to impression manage in public relations, seen as advocacy behavior, had a main effect on the reputation of public relations among undergraduate students and other non-student adults. Finds public relations to be less well-regarded when its practitioners were seen as acting with overt, intentional behaviors for…

Sallot, Lynne M.

2002-01-01

371

Forming impressions of people versus inanimate objects: Social-cognitive processing in the medial prefrontal cortex  

Microsoft Academic Search

Recent neuroimaging research has linked the task of forming a “person impression” to a distinct pattern of neural activation that includes dorsal regions of the medial prefrontal cortex (mPFC). Although this result suggests the distinctiveness of social cognition – the processes that support inferences about the psychological aspects of other people – it remains unclear whether mPFC contributions to this

Jason P. Mitchell; C. Neil Macrae; Mahzarin R. Banajib

2005-01-01

372

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

E-print Network

Variation in individual walking behavior creates the impression of a Lévy flight Sergei Petrovskiia in the distribution of movement lengths. Such distributions occur if individuals move according to a Lévy flight (a indi- viduals such that some individuals move much farther than others. Distinguishing between

373

The Council's annual report on energy efficiency savings recorded an impressive  

E-print Network

The Council's annual report on energy efficiency savings recorded an impressive year in 2010 that businesses understand the impact of efficiency savings on the bottom line. "Major national companies of efficiency compared to power market prices and the cost of new resources; the infusion of American Recovery

374

Privitization and Cutbacks: Social Work and Client Impressions of Service Delivery in Massachusetts.  

ERIC Educational Resources Information Center

Examines agencies in Massachusetts to determine social worker and client impressions of the effects of cutbacks on agency policy and service delivery. Results indicate increased demands on social workers for higher productivity levels, a deterioration of collaborative work environments, an inability to meet treatment goals, and demands for…

Motenko, Aluma Kopito; And Others

1995-01-01

375

First Impressions and Professor Reputation: Influence on Student Evaluations of Instruction  

ERIC Educational Resources Information Center

We examined the effects of professor reputation versus first impressions on student evaluations of instruction. Students in 19 Psychology courses completed course evaluation surveys either before meeting the instructor or 2 weeks into the semester. Both groups then completed the course evaluation again at the end of the semester. Unlike…

Buchert, Stephanie; Laws, Eric L.; Apperson, Jennifer M.; Bregman, Norman J.

2008-01-01

376

Obsessed with Impression Management: A Critical Sociology of Body Image in Capitalist Society  

Microsoft Academic Search

The issues with impression management that we have in society today are perpetuated through the media and how it portrays body image. Just as my family affected me, society and media are influenced by the capitalist\\/consumer society. It is made so that we all have a certain role to play and a certain way to look and if we do

Michelle B. Jacobs

2003-01-01

377

Trait Impressions as Overgeneralized Responses to Adaptively Significant Facial Qualities: Evidence from Connectionist Modeling  

E-print Network

impressions of normal adult faces varying in attractiveness as well as several elderly stereotypes. Activation stereotypes. The evolutionary importance of appropriate responses to unfit individu- als or babies is presumed large effects, comparable in magnitude to the effects of an individual's gender or personality traits

Fellous, Jean-Marc

378

New Interview and Observation Measures of the Broader Autism Phenotype: Impressions of Interviewee Measure  

ERIC Educational Resources Information Center

A 20 item observational measure of social functioning, the Impression of Interviewee rating scale, is one of three measures devised to assess the broader autism phenotype. The sample studied included families containing at least two individuals with autism spectrum disorder; observations were undertaken by the researcher who interviewed the…

Pickles, A.; Parr, J. R.; Rutter, M. L.; De Jonge, M. V.; Wallace, S.; Le Couteur, A. S.; van Engeland, H.; Wittemeyer, K.; McConachie, H.; Roge, B.; Mantoulan, C.; Pedersen, L.; Isager, T.; Poustka, F.; Bolte, S.; Bolton, P.; Weisblatt, E.; Green, J.; Papanikolaou, K.; Bailey, A. J.

2013-01-01

379

Development and initial validation of the Impression Motivation in Sport Questionnaire-Team.  

PubMed

Impression motivation is an important individual difference variable that has been under-researched in sport psychology, partly due to having no appropriate measure. This study was conducted to design a measure of impression motivation in team-sport athletes. Construct validity checks decreased the initial pool of items, factor analysis (n = 310) revealed the structure of the newly developed scale, and exploratory structural equation modeling procedures (n = 406) resulted in a modified scale that retained theoretical integrity and psychometric parsimony. This process produced a 15-item, 4-factor model; the Impression Motivation in Sport Questionnaire-Team (IMSQ-T) is forwarded as a valid measure of the respondent's dispositional strength of motivation to use self-presentation in striving for four distinct interpersonal objectives: self-development, social identity development, avoidance of negative outcomes, and avoidance of damaging impressions. The availability of this measure has contributed to theoretical development, will facilitate research, and offers a tool for use in applied settings. PMID:23798591

Payne, Simon Mark; Hudson, Joanne; Akehurst, Sally; Ntoumanis, Nikos

2013-06-01

380

[Ocular impression test with transfer for the surveillance of vitamin a level].  

PubMed

This study presents the first results of "impression cytology ocular test" in Mauritania for determination of vitamin A rate. This study is based on the community health centers and is not significative of general population. It's a question in this first study of testing this method, realized in some regions of Mauritania (Nouakchott, Dakhlet Nouadhibou, Hodh Gharby, Inchiri, Adrar, Tiris-Zemmour). PMID:2135086

Chassot, P; Cluzeau, C; Luzeau, R; el Joud, R; Barry, K

1990-01-01

381

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

382

Comparing College Students' Value, Outcome, and Impression-Relevant Involvement in Health-Related Issues  

Microsoft Academic Search

The purpose of this study was to examine the role of receiver involvement in the context of health communication. Students (N?=?277) completed Cho and Boster's (2005) measures of value-, outcome-, and impression-relevant involvement across 6 health behaviors, including cigarette smoking, organ and tissue donation, sunscreen use, alcohol use, sexually transmitted disease testing, and nutrition. Confirmatory factor analyses across all 6

Heather M. Marshall; Amber M. Reinhart; Thomas H. Feeley; Frank Tutzauer; Ashley Anker

2008-01-01

383

More than Meets the Ear: A Factor Analysis of Student Impressions of Television Talk Show Hosts.  

ERIC Educational Resources Information Center

To identify the descriptors most frequently associated with four popular television talk show hosts and to isolate the fundamental dimensions of the images of those talk show hosts, a study surveyed 209 students from Memphis State University and the University of Arkansas (Little Rock) about their impressions of Johnny Carson, David Letterman,…

Walker, James R.

384

Laboratory Performance of Zinc Anodes for Impressed Current Cathodic Protection of Reinforced Concrete  

Microsoft Academic Search

Cathodic protection is used increasingly to mitigate steel reinforcement corrosion in concrete. the performance of zinc materials as impressed current anodes was evaluated. The anode materials investigated included rolled zinc sheets, metallized zinc, and 85% Zn-15% Al. The circuit resistance and the adhesion of the anodes was monitored with polarization time. Overall performance of arc-sprayed zinc was good. However, its

R. Brousseau; B. Baldock; M. Arnott

1995-01-01

385

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

ERIC Educational Resources Information Center

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

Harris, Paul B.; Sachau, Daniel

2005-01-01

386

The Deja Connu Phenomenon: A Study in the Formation and Modifiability of First Impressions.  

ERIC Educational Resources Information Center

Working from a rationale derived from cognitive learning theory, this study was designed to investigate the extent to which the formation and modifiability of first impressions may be affected by the perceiver's tendency to associate the stimulus person with some other individual. Fifty subjects rated their initial attractions toward male and…

Noffsinger, Edward B.; Pellegrini, Robert J.

387

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

NSDL National Science Digital Library

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

2008-10-06

388

Children's Impressions of American Indians: A Survey of Suburban Kindergarten and Fifth Grade Children.  

ERIC Educational Resources Information Center

Elementary school children in Mounds View, Minnesota, were surveyed for their impressions of American Indians. The method used was to individually interview every fifth child on the kindergarten and grade 5 class rosters. The report is presented in two sections--data and conclusions. Each of 12 questions is considered separately in the data…

League of Women Voters, New Brighton, Minn.

389

ARTC 4930 001 4 cr. hrs. Art Journaling -Textures and Impressions  

E-print Network

.K. Ludwig Title: Real Life Journals: Designing & Using Handmade Books. Author: Gwen Diehn Title: Book, ArtARTC 4930 001 4 cr. hrs. Art Journaling - Textures and Impressions Study Abroad ­ Orvieto, Italy: 561/289-4991 MDICOSOL@fau.edu Required Texts: Title: True Vision, Authentic Art Journaling. Author: L

Fernandez, Eduardo

390

Creating Physical Personalities For Agents with Faces: Modeling Trait Impressions of the Face  

E-print Network

on a battery of personality invento- ries, intelligence tests, and character scales. From flame- colored hairCreating Physical Personalities For Agents with Faces: Modeling Trait Impressions of the Face York sbrahnam@gc.cuny.edu Abstract. There are both physical and psychological aspects to personality

Bari, Università degli Studi di

391

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. PMID:22291959

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

2012-01-01

392

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

393

The Subjective Impressions of Sixth Grade Urban Adolescents Concerning Their Ability to Achieve Personal Goals  

Microsoft Academic Search

The current study investigated the subjective impressions of sixth grade participants in Going for the Goal (GOAL), a ten-workshop peer-led life skills program, about their ability to get what they want. Four focus groups from three middle schools in a large Southeastern urban area school district were conducted. Analysis of the transcripts from these focus groups indicated that the sixth

Aleta L. Meyer

1999-01-01

394

Impact of Internet Images: Impression-Formation Effects of University Web Site Images  

ERIC Educational Resources Information Center

Institutions of higher education are increasingly becoming dependent on Web-based marketing to reach out to their target audiences. The current empirical study examines the types of impressions formed by prospective students based on exposure to different university Web site images. A between-subjects experiment was conducted using four identical…

Ramasubramanian, Srividya; Gyure, James F.; Mursi, Nasreen M.

2002-01-01

395

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

396

The Influence of Physical Attractiveness and Dress on Campus Recruiters' Impressions of Female Job Applicants.  

ERIC Educational Resources Information Center

The influence of physical attractiveness, dress, and job type upon 300 college recruiters' impressions of females' employment potential was investigated. Subjects rated female applicants from a photograph on eight employment potential statements. Results indicate that the applicant's style of dress exerted a consistent influence on recruiters'…

Johnson, Kim K. P.; Roach-Higgins, Mary E.

1987-01-01

397

X-ray diffraction study of crystalline phases of calcium sulphate in alginate impression materials.  

PubMed

In the present study the crystalline phases of calcium sulphate present in various commercially available alginate impression materials were identified by means of x-ray diffraction. The diffractograms obtained indicated that the predominant crystalline phase in most materials was calcium sulphate dihydrate and confirmed the presence of calcium sulphate hemihydrate in some products. PMID:9021340

Anastassiadou, V; Dolopoulou, V; Kaloyannides, A

1996-01-01

398

Admission Officers' Impressions of Homeschooled Applicants in Evangelical and Nonevangelical Colleges and Universities  

ERIC Educational Resources Information Center

Impressions of admission officers toward homeschooled applicants were examined. Specifically, this study sought to ascertain whether the perceptions of admission officers adhered to the common stereotype that homeschoolers are brighter and yet socially less well-adjusted than average. The responses of 121 admission officers were analyzed across…

McCulloch, Donald S.; Savage, Alexandra; Schmal, Liz

2013-01-01

399

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

E-print Network

centimeters and 5 centimeters from the center of the black hole. Space Math http://spacemath.gsfc.nasa.gov #12 the 'yellow to white' scheme below. Space Math http://spacemath.gsfc.nasa.gov #12;79Black Holes - Hot Stuff! Artist's impression of gas falling into a black hole Image credit: NASA

400

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

E-print Network

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

New Hampshire, University of

401

The Effects of a Modified Neurological Impress Method on Developing Decoding Skills.  

ERIC Educational Resources Information Center

A study evaluated the effects that a modified neurological impress method (a process whereby a student and a teacher read simultaneously) had on developing a student's decoding skills. Forty-two students in grades one through eight were randomly assigned to one of four groups: (1) a control group; (2) a group in which students read simultaneously…

Mikkelsen, Vincent P.

402

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

Code of Federal Regulations, 2010 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...optical impression system for computer assisted design and manufacturing...digital methods for use in the computer-assisted design and manufacturing...equivalent type of sensor and a computer with software. (b)...

2010-04-01

403

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

Code of Federal Regulations, 2011 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...optical impression system for computer assisted design and manufacturing...digital methods for use in the computer-assisted design and manufacturing...equivalent type of sensor and a computer with software. (b)...

2011-04-01

404

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

Code of Federal Regulations, 2013 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...optical impression system for computer assisted design and manufacturing...digital methods for use in the computer-assisted design and manufacturing...equivalent type of sensor and a computer with software. (b)...

2013-04-01

405

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

Code of Federal Regulations, 2012 CFR

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...optical impression system for computer assisted design and manufacturing...digital methods for use in the computer-assisted design and manufacturing...equivalent type of sensor and a computer with software. (b)...

2012-04-01

406

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

...ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL...optical impression system for computer assisted design and manufacturing...digital methods for use in the computer-assisted design and manufacturing...equivalent type of sensor and a computer with software. (b)...

2014-04-01

407

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

408

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

Microsoft Academic Search

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

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

2010-01-01

409

Impression-oriented music courseware and its application in elementary schools  

Microsoft Academic Search

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

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

2010-01-01

410

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

ERIC Educational Resources Information Center

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…

Miwa, Yoshiko; Hanyu, Kazunori

2006-01-01

411

Conception:CommeUnSoleil-impression:servicecommunicationetditionUniversitParis13-septembre2011 (entre libre et gratuite)  

E-print Network

#12;Conception:CommeUnSoleil-impression:servicecommunicationetéditionUniversitéParis13-septembre Laboratoire Bio-ingénierie de polymères cardiovasculaires, Isabelle Bataille, Vuk Milisic, Sébastien Li médecine préventive et du département des sports de l'Université Paris 13 vous propose : test d

Banderier, Cyril

412

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

ERIC Educational Resources Information Center

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

Greasley, Pete; Cassidy, Andrea

2010-01-01

413

Further Experiments to Investigate the Influence of Robot Motions on Human Impressions  

Microsoft Academic Search

This paper investigates human impressions of the robot's reaching motion based on psychophysiological experiments. There has been an increasing development of robots that move in the immediate vicinity of humans. It is important to ensure the security and relief of humans in the presence of robots. In our previous works, we employed heart rate variabilities, skin potential responses, and skin

Naohiko Hanajima; Youhei Ohta; Y. Sakurai; H. Hikita; M. Yamashita

2006-01-01

414

INTRODUCTION The swimming of fish and the flight of insects are impressive feats  

E-print Network

1324 INTRODUCTION The swimming of fish and the flight of insects are impressive feats of nature, 2008). Most current techniques for extracting 3D body and wing kinematics of flying animals rely-eyed researchers. More automated methods, similar to those developed for motion tracking of cockroaches and fish

Cohen, Itai

415

Evaluation of different approaches for using a laser scanner in digitization of dental impressions  

PubMed Central

PURPOSE This study aimed to investigate the potential clinical application of digitized silicone rubber impressions by comparing the accuracy of zirconia 3-unit fixed partial dentures (FPDs) fabricated from 2 types of data (working model and impression) obtained from a laser scanner. MATERIALS AND METHODS Ten working models and impressions were prepared with epoxy resin and vinyl polysiloxane, respectively. Based on the data obtained from the laser scanner (D-700; 3Shape A/S, Copenhagen, Denmark), a total of 20 zirconia frameworks were prepared using a dental CAD/CAM system (DentalDesigner; 3shape A/S, Copenhagen, Denmark / Ener-mill, Dentaim, Seoul, Korea). The silicone replicas were sectioned into four pieces to evaluate the framework fit. The replicas were imaged using a digital microscope, and the fit of the reference points (P1, P2, P3, P4, P5, P6, and P7) were measured using the program in the device. Measured discrepancies were divided into 5 categories of gaps (MG, CG, AWG, AOTG, OG). Data were analyzed with Student's t-test (?=0.05), repeated measures ANOVA and two-way ANOVA (?=0.05). RESULTS The mean gap of the zirconia framework prepared from the working models presented a narrower discrepancy than the frameworks fabricated from the impression bodies. The mean of the total gap in premolars (P=.003) and molars (P=.002) exhibited a statistical difference between two groups. CONCLUSION The mean gap dimensions of each category showed statistically significant difference. Nonetheless, the digitized impression bodies obtained with a laser scanner were applicable to clinical settings, considering the clinically acceptable marginal fit (120 µm). PMID:24605202

Lee, Wan-Sun; Kim, Woong-Chul; Kim, Hae-Young; Kim, Wook-Tae

2014-01-01

416

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. PMID:24723954

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

2014-01-01

417

DESIGNING A HIGH RESOLUTION 3D IMAGING DEVICE FOR FOOTPRINT AND TIRE TRACK IMPRESSIONS AT CRIME SCENES1  

E-print Network

...................................................................................................................................................18 #12;A high resolution 3d impression imaging device 2 1 INTRODUCTION In crime scene investigationsDESIGNING A HIGH RESOLUTION 3D IMAGING DEVICE FOR FOOTPRINT AND TIRE TRACK IMPRESSIONS AT CRIME SCENES1 TR-CIS-0416-12 Ruwan Egoda Gamage Abhishek Joshi Jiang Yu Zheng Mihran Tuceryan A Technical

Tuceryan, Mihran

418

The Influence of Job Familiarity and Impression Management on Self-Report Measure Scale Scores and Response Latencies  

Microsoft Academic Search

Two studies were conducted to examine the effects of job familiarity and impression management on response latencies and scale scores for measures of personality and situational judgment. In a laboratory study using university students and a field study using U.S. Border Patrol Agent applicants, impression management was generally associated with faster personality item responses when job familiarity was high and

Nicholas L. Vasilopoulos; Richard R. Reilly; Julia A. Leaman

2000-01-01

419

The influence of job familiarity and impression management on self-report measure scale scores and response latencies.  

PubMed

Two studies were conducted to examine the effects of job familiarity and impression management on response latencies and scale scores for measures of personality and situational judgment. In a laboratory study using university students and a field study using U.S. Border Patrol Agent applicants, impression management was generally associated with faster personality item responses when job familiarity was high and with slower responses when job familiarity was low. Both impression management and job familiarity were associated with personality item responses that were more likely to lead to a job offer. The field study revealed a similar pattern of results for situational judgment scale response latencies, although only impression management was associated with item responses that were more likely to lead to a job offer. The implications for using response latencies to detect impression management on self-report measures are discussed. PMID:10740956

Vasilopoulos, N L; Reilly, R R; Leaman, J A

2000-02-01

420

Effect of composite microstructure on electrical and mechanical properties of poly(vinyl acetate) composites with carbon black and clay.  

E-print Network

The electrical and mechanical behavior of carbon black filled poly(vinyl acetate) latex-based and solution-based polymer composites was examined. A set of experiments were performed to distinguish composites with a segregated network (emulsion...

Miriyala, Sethu M.

2009-05-15

421

Effects of Concentration of Organically Modified Nanoclay on Properties of Sulfonated Poly(vinyl alcohol) Nanocomposite Membranes  

E-print Network

Electrolyte nanocomposite membranes for proton exchange membrane fuel cells and direct methanol fuel cells were prepared by carrying out a sulfonation of poly(vinyl alcohol) with sulfosuccinic acid and adding a type of ...

Sanglimsuwan, Apiradee

422

Polyvinyl chloride. January 1980-February 1992 (Citations from the NTIS Data Base). Rept. for Jan 80-Feb 92  

SciTech Connect

The bibliography contains citations concerning preparation, properties, composition, toxicity, and health hazards of polyvinyl chloride. Topics include, aging tests, combustion products, occupational safety and health, photolysis, thermal degradation, and pollution. (Contains 116 citations with title list and subject index.)

Not Available

1992-01-01

423

Polyvinyl alcohol-coated hybrid fiber grating for relative humidity sensing.  

PubMed

A relative humidity (RH) sensor based on a hybrid fiber grating coated with polyvinyl alcohol is proposed and demonstrated experimentally. The hybrid fiber grating is formed by superimposing a normal fiber Bragg grating (FBG) and a tilted-FBG around the same position of a single-mode fiber so that it can work in the reflection mode. Optical power of the reflected signal changes with the refractive index of the moisture sensitive polyvinyl alcohol, and humidity measurement can be realized. Experimental results show that the measurement range is 30 to 95% with the maximum sensitivity of 0.737 nW?% RH. The average response time is ?2 s and the measurement is nearly insensitive to temperature. Compared with the wavelength detection method used in normal FBG-based relative humidity sensors, the intensity demodulation method in this report is simpler and more cost-efficient. PMID:21806281

Dong, Xinyong; Li, Tao; Liu, Yang; Li, Yi; Zhao, Chun-Liu; Chan, Chi Chiu

2011-07-01

424

In-situ cross linking of polyvinyl alcohol. [application to battery separator films  

NASA Technical Reports Server (NTRS)

A method of producing a crosslinked polyvinyl alcohol structure, such as a battery separator membrane or electrode envelope is described. An aqueous solution of a film-forming polyvinyl alcohol is admixed with an aldehyde crosslinking agent a basic pH to inhibit crosslinking. The crosslinking agent, perferably a dialdehyde such as glutaraldehyde, is used in an amount of from about 1/2 to about 20% of the theoretical amount required to crosslink all of the hydroxyl groups of the polymer. The aqueous admixture is formed into a desired physical shape, such as by casting a sheet of the solution. The sheet is then dried to form a self-supporting film. Crosslinking is then effected by immersing the film in aqueous acid solution. The resultant product has excellent properties for use as a battery separator.

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

1981-01-01

425

Synthesis and characterization of polyvinyl alcohol based multiwalled carbon nanotube nanocomposites  

NASA Astrophysics Data System (ADS)

Multiwalled carbon nanotubes were synthesized by chemical vapor deposition over an Fe-Co/alumina catalyst. Nanotubes were then oxidized and grafted with polyvinyl alcohol (PVA). The obtained nanostructure was characterized by Raman spectroscopy, XRD, FTIR, EDX, SEM, TEM and TGA methods. FTIR confirmed the presence of the characteristic peaks of the anticipated ester group. The formation of polymer nanocomposites based on polyvinyl alcohol and multiwalled carbon nanotubes was confirmed by SEM and TEM. High resolution electron micrographs revealed that the primary binding sites for PVA grafting are the sidewall defects of the nanotubes. The novelty of this work is the use of the Fischer esterification reaction for creating the permanent link between the nanotubes and the PVA matrix.

Malikov, E. Y.; Muradov, M. B.; Akperov, O. H.; Eyvazova, G. M.; Puskás, R.; Madarász, D.; Nagy, L.; Kukovecz, Á.; Kónya, Z.

2014-07-01

426

First impressions.  

PubMed

'During a consultation there are two people at work. While the doctor is searching for a diagnosis, the patient is quietly summing up the doctor. And it is often the patient who reaches his conclusion first.' This quote from William Evans illustrates how the consultation involves a two-way analysis by both doctor and patient. PMID:8220841

Short, D

427

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

428

First Impressions.  

ERIC Educational Resources Information Center

Discusses an art project that focuses on fine arts prints. Uses three printmaking techniques: (1) stamping, (2) monotypes, and (3) intaglio (drypoint), with a focus on monotypes. Explains that the students created self-portraits using the monoprint technique by drawing their faces on a mirror and pulling the print off this surface. (CMK)

Greenman, Geri

2001-01-01

429

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

430

Unique Impressions  

ERIC Educational Resources Information Center

For much of the 20th century, it was the engine that powered one of nation's most massive retail operations. By the beginning of the 21st century, the historic building was no longer needed to supply energy to what remained of the once bustling Sears, Roebuck and Co. campus on the West Side of Chicago. The original purpose of the Power House, as…

Kennedy, Mike

2008-01-01

431

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

432

Disruption of the protective properties of the polyvinyl chloride coating under the effect of microorganisms  

SciTech Connect

The presence of sulfate-reducing bacteria results in a reduction of the protective properties of polyvinyl chloride (PVC) film coatings. The authors examine the effect of other types of soil microorganisms. Investigations were carried out with the cultures of bacteria Pseudomonas fluorescens B-22 and fungus Aspergillus niger van Tieghem F-1119 which are almost always present in corrosion regions in the routes of transmission pipelines. The microorganisms were grown in a mineral medium with glucose (Ps. fluorescens) and sucrose (A. niger).

Mogil'nitskii, G.M.; Sagatelyan, R.T.; Kutishcheva, T.N.; Zhukova, S.V.; Kerimov, S.I.; Parfenova, T.B.

1987-09-01

433

Assessing biodegradability of plastics based on poly(vinyl alcohol) and protein wastes  

Microsoft Academic Search

Research was conducted into biodegradability of mixed polymer films based on poly(vinyl alcohol), protein hydrolyzate (collagen hydrolyzate from wastes after chrome tanning) and glycerol in an aqueous aerobic environment. Evaluation of biodegradation was based on carbon dioxide produced in the gas phase. Pure PVAL was degraded by a current mixed culture for water-treatment (unadapted) only after an approx. 10-day lag

Jarom??r Hoffmann; Iveta ?ezn???ková; Jarmila Kozáková; Jan R?ži?ka; Pavol Alexy; Dušan Bakoš; Lenka Precnerová

2003-01-01

434

Blood compatibility of novel poly(?-glutamic acid)\\/polyvinyl alcohol hydrogels  

Microsoft Academic Search

Sodium poly(?-glutamic acid) (PGA), a water-soluble and biodegradable polypeptide, was reacted with polyvinyl alcohol (PVA) to form hydrogel without any chemical treatment. The gelation occurred probably due to physical cross-linking of polymer chains by interpenetrating hydrogen bonding. From the results of thermal analysis, PGA\\/PVA exhibited better thermal stability than native PVA. Although the swelling ratio decreased with the increase of

Wen-Ching Lin; Da-Guang Yu; Ming-Chien Yang

2006-01-01

435

Effect of functionalized silica particles on cross-linked poly(vinyl alcohol) proton conducting membranes  

Microsoft Academic Search

A family of proton conducting membranes based on cross-linked poly(vinyl alcohol), PVA, has been synthesized and characterized.\\u000a The influence of surface-functionalized silica particles on the membrane properties has been evaluated by means of 1H-NMR, vibrational spectroscopy, thermal analysis and electrochemical characterization. The study revealed that the crystallinity\\u000a of the polymer, the proton diffusivity and the water retention are strongly affected

M. A. Navarra; A. Fernicola; S. Panero; A. Martinelli; A. Matic

2008-01-01

436

Cibacron Blue F3GA Attached Poly(Vinyl Alcohol) Particles for Specific Albumin Adsorption  

Microsoft Academic Search

Poly(vinyl alcohol) (PVAL) particles (average size: 50 ?m) were prepared in the present study by chemical crosslinking of PVAL with glutaraldehyde in an organic dispersion oil phase. Cibacron Blue F3G-A was attached to these hydrophilic PVAL particles. Bovine serum albumin (BSA) adsorption onto these dye-attached PVAL particles from aqueous solutions containing different amounts of BSA in three different salts (i.e.,

Adil Denizli; Ali Tuncel; Ahmet Kozluca; Kutay Ecevit; Erhan Pi?kin

1997-01-01

437

Polyelectrolyte complex (PEC) modified by poly(vinyl alcohol) and their blend membranes for pervaporation dehydration  

Microsoft Academic Search

Soluble polyelectrolyte complex (PEC), made of poly(2-methacryloyloxy ethyl trimethylammonium chloride)\\/sodium carboxymethyl cellulose (PDMC\\/CMCNa), was modified by poly(vinyl alcohol) (PVA) with the content from 0 to 50wt% to improve the PEC mechanical properties. It was found that the best mechanical properties of PEC\\/PVA blend containing 30wt% PVA (PEC\\/PVA7030) were obtained. The tensile strength, modulus and elongation at break are about 1.5,

Meihua Zhu; Jinwen Qian; Qiang Zhao; Quanfu An; Yihu Song; Qiang Zheng

2011-01-01

438

Nanoporous Nanocomposite Hydrogels Composed of Polyvinyl Alcohol and Na-montmorillonite  

Microsoft Academic Search

Polyvinyl alcohol nanoporous nanocomposite hydrogels containing various levels of Na-montmorillonite were prepared by a cyclic freezing-thawing technique. An exfoliated morphology of silicate layers was observed for the nanocomposite hydrogels. The uniaxial tensile test indicated that the tensile modulus and tensile strength of the nanocomposite hydrogels increased with increasing Na-montmorillonite content, while their elongation-at-break values decreased. The results showed that by

M. SIROUSAZAR; M. KOKABI; Z. M. HASSAN; A. R. BAHRAMIAN

2012-01-01

439

Development of a Hypertrophic Ovarian Artery After Uterine Artery Embolization with Polyvinyl Alcohol Particles  

SciTech Connect

Uterine artery embolization (UAE) for the treatment of symptomatic leiomyomata has shown excellent short-term clinical efficacy and minimal complications, yet recurrences after successful treatments at mid- and long-term follow-up have been reported. Exact etiologies for such recurrences have not been fully understood. We present a case of symptom recurrence with the development of a hypertrophic ovarian artery after successful UAE with polyvinyl alcohol particles, successfully treated with ovarian and repeat UAEs.

Kim, Hyun S., E-mail: sikhkim@jhmi.edu; Paxton, Ben E. [Johns Hopkins University School of Medicine, Russell H. Morgan Department of Radiology and Radiological Science (United States)

2007-09-15

440

Synthesis and thermal study of octahedral silver nano-plates in polyvinyl alcohol (PVA)  

Microsoft Academic Search

Octahedral silver nano-plates were synthesized from aqueous solution of silver nitrate and polyvinyl alcohol. The colloid formed is dried on glass plates by simple dip-coating method to inhibit the growth of the particles, and to analyze the samples. Samples were characterized by X-ray diffractometer, transmission electron microscope (TEM), thermo-gravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques. The UV–Vis absorption

T. Abdul kareem; A. Anu kaliani

2011-01-01

441

Optical property of CdS QD's embeded in Polyvinyl alcohol  

Microsoft Academic Search

We fabricated the CdS semiconductor quantum dots(QDs) embedded in the polyvinyl alcohol. By measuring the absorption spectrum of PVA with CdS, we could determine the radius of QDs. We confirm that as it increasing the mole ratio (CdCl2\\/RSH) in the mixture, the mean radius of the QDs decreased and the band gap energy increased. When added the RSH, absorption peak

Sung Yong Ha; II Gon Kim; Dong sun Yoo; Ki Wan Jang; Jung Du Lee

2007-01-01

442

Poly(vinyl alcohol)-based polymer electrolyte membranes containing polyrotaxane  

Microsoft Academic Search

Polymer electrolyte membranes featuring ionic channels have been prepared by sulfonation of crosslinked poly(vinyl alcohol)\\/polyrotaxane membranes. The ionic channels were prepared using rod-like polyrotaxanes, created as an inclusion complex between poly(ethylene glycol) (PEG) and ?-cyclodextran. The size of the polyrotaxane was controlled by the molecular weight of PEG. Proton conductivity as well as methanol permeability increased as the amount of

Ji Hwan Son; Yong Soo Kang; Jongok Won

2006-01-01

443

Holograms in polyvinyl alcohol photosensitized with CuCl2(2H2O)  

Microsoft Academic Search

We propose the use of polyvinyl alcohol photosensitized with copper chloride dihydrated CuCl2(2H2O) as a photosensitive material for recording holographic gratings. We obtained different dissolutions changing concentration of photosensitive agent and varying their pH factor, refraction index, and optical density for each sample. We registered diffraction gratings by holographic methods. The behaviors of diffraction efficiency parameters of holographic gratings regarding

Arturo Olivares-Pérez; Mary Paz Hernández-Garay; Isrrael Fuentes-Tapia; Juan Carlos Ibarra-Torres

2011-01-01

444

Poly(vinyl alcohol) cryogel, multi-layer artery phantoms for optical coherence tomography  

NASA Astrophysics Data System (ADS)

In this paper, we present recent development of phantoms of coronary arteries with representative mechanical properties. The phantoms were made of poly(vinyl alcohol) cryogel (PVA-C). Multilayer phantoms were fabricated by an overmoulding process. The optical properties are adjusted in each layer by the different number of freeze-thaw cycles in combination with additives. The mechanical properties of the multilayer phantoms are characterized, and various means for improving the strain hardening are investigated.

Bisaillon, Charles-Etienne; Campbell, Gordon; Pazos, Valérie; Lamouche, Guy

2011-03-01

445

Preparation and Characterization of Modified Cellulose Fiber-Reinforced Polyvinyl Alcohol\\/Polypyrrolidone Hybrid Film Composites  

Microsoft Academic Search

In this work, cellulose was modified by using 2-(trifluromethyl)benzoylchloride by base catalyzed reaction. Modification of cellulose was confirmed by IR studies. The biodegradable composite films were developed by a film casting method using modified cellulose with poly(vinyl alcohol) and polypyrrolidone in different compositions. Film composites showed good biodegradability. Better barrier and mechanical properties showed by film composites as the percentage

Sandeep S. Laxmeshwar; S. Viveka; D. J. Madhu Kumar; Dinesha; R. F. Bhajanthri; G. K. Nagaraja

2012-01-01

446

Natural Fiber Reinforced Poly(vinyl chloride) Composites: Effect of Fiber Type and Impact Modifier  

Microsoft Academic Search

Poly(vinyl chloride) (PVC) and natural fiber composites were prepared by melt compounding and compression molding. The influence\\u000a of fiber type (i.e., bagasse, rice straw, rice husk, and pine fiber) and loading level of styrene-ethylene-butylene-styrene\\u000a (SEBS) block copolymer on composite properties was investigated. Mechanical analysis showed that storage modulus and tensile\\u000a strength increased with fiber loading at the 30% level for

Y. Xu; Q. Wu; Y. Lei; F. Yao; Q. Zhang

2008-01-01

447

Boron-containing poly(vinyl alcohol) as a ceramic precursor  

Microsoft Academic Search

In this paper, a preceramic precursor, prepared by condensation reaction from poly(vinyl alcohol) (PVA) and boric acid (B(OH)3) in a B–OH: PVA-OH molar ratio of 1:1, was synthesized, as a potential precursor of lower-temperature route for ceramic material. The polymer-to-ceramic conversion was studied by thermogravimetry (TG), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The kinetics parameters, such as

Pauline M. Barros; I. Valéria P. Yoshida; Marco A. Schiavon

2006-01-01

448

Vinyl chloride and polyvinyl chloride: Toxicology. (Latest citations from the Life Sciences Collection database). Published Search  

SciTech Connect

The bibliography contains citations concerning the toxicity of vinyl chloride and polyvinyl chloride following short- and long-term exposure. The citations explore how these compounds are metabolized and consider their carcinogenic and teratogenetic potential. Methodologies to quantitate their presence in atmospheric dust and body tissues are discussed. Occupational hazards are also noted.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

NONE

1995-12-01

449

Poly(vinyl alcohol)-heparin hydrogels as sensor catheter membranes  

Microsoft Academic Search

Poly(vinyl alcohol)-heparin hydrogels with varying water content were synthesized for use as sensor catheter membranes. Films were cast from aqueous mixtures of poly(viny) alcohol) (PVA), a photosensitive cross-linker p-diazonium diphenyl amine polymer (PA), glutaraldehyde (GA) and heparin. After drying, the films were cross-linked by successive UV irradiation and heat treatment. To get an indication about the cross-linking density of the

E. Brinkman; Does van der L; A. Bantjes

1991-01-01

450

Thermooxidative degradation of poly(vinyl chloride) and chlorinated polyethylene with different Ca\\/Zn carboxylates  

Microsoft Academic Search

The thermooxidative degradation of poly(vinyl chloride) (PVC), chlorinated polyethylene (CPE) and PVC\\/CPE blend 50\\/50 was\\u000a investigated by means of dynamic and isothermal thermogravimetric analysis in the flowing atmosphere of air. To estimate the\\u000a thermooxidative stability of the samples the characteristics of thermogravimetric (TG) curves were used. Kinetic parameters\\u000a (the apparent activation energy E and preexponential factor Z) were calculated after

N. S. Vrande?i?; I. Klari?; T. Kova?i?

2003-01-01

451

Thermooxidative degradation of poly(vinyl chloride)\\/chlorinated polyethylene blends investigated by thermal analysis methods  

Microsoft Academic Search

The thermooxidative degradation of poly(vinyl chloride)\\/chlorinated polyethylene (PVC\\/CPE) blends of various compositions was investigated by means of thermal analysis methods: differential scanning calorimetry (DSC) and thermogravimetry (TG). By using DSC it was found that all investigated PVC\\/CPE blends were heterogeneous. The main reaction of PVC degradation at moderate temperatures is dehydrochlorination, which is also a dominant reaction in CPE degradation.

Nataša Stipanelov Vrande?i?; Ivka Klari?; Tonka Kova?i?

2004-01-01

452

Nonisothermal degradation of poly(vinyl chloride)\\/methylmethacrylate-butadiene-styrene blends  

Microsoft Academic Search

The thermal degradation of poly(vinyl chloride)\\/methylmethacrylate-butadiene-styrene (PVC\\/MBS) blends was studied by nonisothermal thermogravimetry in nitrogen. Measurements were carried out in the temperature range 323–823K. The kinetic parameters were determined by applying Flynn–Wall–Ozawa and Kissinger’s methods. According to the compensation parameters the mechanism of degradation remains the same on adding the MBS; only the kinetics change. The thermal stability of the

B Andri?i?; T Kova?i?

1999-01-01

453

The kinetic parameters for the evaporation of plasticizers from plasticized poly(vinyl chloride)  

Microsoft Academic Search

The process of loss of plasticizers: dioctyl phthalate, diisononyl phthalate, benzylbutyl phthalate, dioctyl adipate, phosphate plasticizer Reofos, polymeric plasticizer Reoplex and epoxidized soybean oil from plasticized poly(vinyl chloride) folies was studied by the method of isothermal thermogravimetry in the temperature range 120–150°C. The investigated samples contained ca. 10–40wt.% of plasticizers. The rate constants of the process of loss of plasticizers

Tonka Kova?i?; Željko Mrkli?

2002-01-01

454

Thermogravimetric investigation of volatility of dioctyl phthalate from plasticized poly(vinyl chloride)  

Microsoft Academic Search

The process of volatilization of dioctyl phthalate (DOP) plasticizer from plasticized poly(vinyl chloride) (PVC) folies was studied by the method of isothermal thermogravimetry in the temperature range of 120–150°C. The investigated samples contained 10.15 to 37.11wt% of DOP. The rate constants of the process of plasticizer volatilization were calculated and the dependence of rate constant on the initial concentration of

Željko Mrkli?; Tonka Kova?i?

1998-01-01

455

Kinetics of thermooxidative degradation of poly(vinyl chloride)\\/chlorinated polyethylene blends  

Microsoft Academic Search

The thermooxidative degradation of poly(vinyl chloride)\\/chlorinated polyethylene blends of different compositions was investigated by means of dynamic thermogravimetry in flowing atmosphere of synthetic air in temperature range 50–650 °C. Kinetic analysis was applied to the first basic degradation step (up to 400 °C) where the main degradation processes were the dehydrochlorination of PVC and CPE. For calculation of the apparent activation energy

Nataša Stipanelov Vrande?i?; Ivka Klari?; Tonka Kova?i?

2004-01-01

456

Kinetics of isothermal thermooxidative degradation of poly(vinyl chloride)\\/chlorinated polyethylene blends  

Microsoft Academic Search

The thermooxidative degradation of poly(vinyl chloride)\\/chlorinated polyethylene blends of different compositions was investigated by means of isothermal thermogravimetry in flowing atmosphere of synthetic air at temperatures 240–270°C. The main degradation processes are dehydrochlorination of PVC and CPE. For calculation of the apparent activation energy and apparent pre-exponential factor two kinetic methods were used: isoconversional method and Prout–Tompkins method. True compensation

Nataša Stipanelov Vrande?i?; Branka Andri?i?; Ivka Klari?; Tonka Kova?i?

2005-01-01

457

Analysis of phthalic acid diesters, monoester, and other plasticizers in polyvinyl chloride household products in Japan  

Microsoft Academic Search

The aim of this study was to determine the concentrations of six phthalic acid diesters (PAEs) [di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), di-n-octyl phthalate (DNOP), and diisodecyl phthalate (DIDP)], two non-phthalic plasticizers [di(2-ethylhexyl) adipate (DEHA), 2,2,4-trimethyl-1,3-pentanediol diisobutylate (TMPDIB)], and mono 2-ethylhexyl phthalate(MEHP) in polyvinyl chloride (PVC) household products that children often places in

Tsuyoshi Kawakami; Kazuo Isama; Atsuko Matsuoka

2011-01-01

458

Electrodialytic Transport Properties of Anion-Exchange Membranes Prepared from Poly(vinyl alcohol) and Poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride)  

PubMed Central

Random-type anion-exchange membranes (AEMs) have been prepared by blending poly(vinyl alcohol) (PVA) and the random copolymer-type polycation, poly(vinyl alcohol-co-methacryloyl aminopropyl trimethyl ammonium chloride) at various molar percentages of anion-exchange groups to vinyl alcohol groups, Cpc, and by cross-linking the PVA chains with glutaraldehyde (GA) solution at various GA concentrations, CGA. The characteristics of the random-type AEMs were compared with blend-type AEMs prepared in our previous study. At equal molar percentages of the anion exchange groups, the water content of the random-type AEMs was lower than that of the blend-type AEMs. The effective charge density of the random-type AEMs increased with increasing Cpc and reached a maximum value. Further, the maximum value of the effective charge density increased with increasing CGA. The maximum value of the effective charge density, 0.42 mol/dm3, was obtained for the random-type AEM with Cpc = 4.2 mol % and CGA = 0.15 vol %. A comparison of the random-type and blend-type AEMs with almost the same Cpc showed that the random-type AEMs had lower membrane resistance than the blend-type ones. The membrane resistance and dynamic transport number of the random-type AEM with Cpc = 6.0 mol % and CGA = 0.15 vol % were 4.8 ? cm2 and 0.83, respectively. PMID:24958543

Jikihara, Atsushi; Ohashi, Reina; Kakihana, Yuriko; Higa, Mitsuru; Kobayashi, Kenichi

2012-01-01

459

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

PubMed

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

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

2009-06-01

460

New SmCG phases in a hydrogen-bonded bent-core liquid crystal featuring a branched siloxane terminal group.  

PubMed

In this study, we synthesized three analogous bent-core molecules, a hydrogen-bonded complex and a covalent-bonded compound with branched siloxane units (H-SiO and C-SiO, respectively) and a hydrogen-bonded complex with an alkyl unit (H-Alk), and investigated the effects of the hydrogen bonding and branched siloxane terminal units on their mesomorphic properties. The covalent-bonded compound C-SiO and the hydrogen-bonded complex H-Alk exhibited typical SmCP phases; in contrast, the hydrogen-bonded complex H-SiO exhibited a series of general tilt smectic (SmCG) phases with highly ordered layer structures (i.e., SmC?G(2)P(F)-USmCG(2)P(A)-SmCG(2)P(F)-SmCGP(F) upon cooling). During the SmCG-type phase transition process, a 2D-modulated ribbon structure transferred into highly ordered layers via undulated layers, as the hydrogen-bonding strength increased with reduced temperatures. As the SmCG domains were aligned under dc electric fields, a gradual decrease in the leaning angle from ca. 60° to 50° (while the tilt angle kept at ca. 31°) could be determined by in situ wide-angle X-ray scattering (WAXS). Combined with Fourier transform infrared and Raman spectroscopic data, our results suggest that the change in the leaning angle was governed by the competition of the hydrogen bonds and microsegregation of siloxane units within the bilayer structure of the hydrogen-bonded complex H-SiO. In addition, the ferroelectric-(antiferroelectric)-ferroelectric transitions proven by the switching current responses in the SmCG-type phases of H-SiO reveal that the polar switching occurred through collective rotations around the long axis of H-SiO. Therefore, novel SmCG phases with a series of highly ordered 2D-structures were induced by the effects of the hydrogen bonding and branched terminal siloxane unit in the bent-core hydrogen-bonded LC complex H-SiO. PMID:21870780

Chen, Wei-Hong; Chuang, Wei-Tsung; Jeng, U-Ser; Sheu, Hwo-Shuenn; Lin, Hong-Cheu

2011-10-01

461

Studies on silicon NMR characterization and kinetic modeling of the structural evolution of siloxane-based materials and their applications in drug delivery and adsorption  

NASA Astrophysics Data System (ADS)

This dissertation presents studies of the synthetic processes and applications of siloxane-based materials. Kinetic investigations of bridged organoalkoxysilanes that are precursors to organic-inorganic hybrid polysilsesquioxanes are a primary focus. Quick gelation despite extensive cyclization is found during the polymerization of bridged silane precursors except for silanes with certain short bridges. This work is an attempt to characterize and understand some of the distinct features of bridged silanes using experimental characterization, kinetic modeling and simulation. In addition to this, the dissertation shows how the properties of siloxane-materials can be engineered for drug delivery and adsorption. The phase behavior of polymerizing mixtures is first investigated to identify the solutions that favor kinetic characterization. Microphase separation is found to cause gradual loss of NMR signal for certain initial compositions. Distortionless Enhancement by Polarization Transfer 29Si NMR is employed to identify the products of polymerization of some short-bridged silanes under no signal loss conditions. This technique requires knowing indirect 29Si-1H scalar coupling constants which sometimes cannot be measured due to second-order effects. However, the B3LYP density functional method with 6-31G basis set is found to predict accurate 29Si- 1H coupling constants of organoalkoxysilanes and siloxanes. The scalar coupling constants thus estimated are employed to resolve non-trivial coupled NMR spectra and quantitative kinetic modeling is performed using the DEPT Si NMR transients. In order to investigate the role of the organic bridging group, the structural evolution of bridged and non-bridged silanes are compared using Monte Carlo simulations. Kinetic and simulation models suggest that cyclization plays a key role right from the onset of polymerization for bridged silanes even more than in non-bridged silanes. The simulations indicate that the carbosiloxane rings formed from short-bridged precursors slow down but do not prevent gelation. The tuning of siloxane-based materials for adsorption technologies are also discussed here. In the first example, antioxidant enzyme loading is investigated as a means to reduce oxidative stress generated by silica nanoparticle drug carriers. Materials are engineered for promising enzyme loading and protection from proteolysis. Second, the potential of copper sulfate impregnation to enhance adsorption of ammonia by silica is explored by molecular simulation. KEYWORDS: Sol-gel Polymerization, Kinetic Investigation, Si NMR, Bridged Silanes, DFT Calculations.

Ambati, Jyothirmai

462

Stress Strengthens Memory of First Impressions of Others' Positive Personality Traits  

PubMed Central

Encounters with strangers bear potential for social conflict and stress, but also allow the formation of alliances. First impressions of other people play a critical role in the formation of alliances, since they provide a learned base to infer the other's future social attitude. Stress can facilitate emotional memories but it is unknown whether stress strengthens our memory for newly acquired impressions of other people's personality traits. To answer this question, we subjected 60 students (37 females, 23 males) to an impression-formation task, viewing portraits together with brief positive vs. negative behavior descriptions, followed by a 3-min cold pressor stress test or a non-stressful control procedure. The next day, novel and old portraits were paired with single trait adjectives, the old portraits with a trait adjective matching the previous day's behavior description. After a filler task, portraits were presented again and subjects were asked to recall the trait adjective. Cued recall was higher for old (previously implied) than the novel portraits' trait adjectives, indicating validity of the applied test procedures. Overall, recall rate of implied trait adjectives did not differ between the stress and the control group. However, while the control group showed a better memory performance for others' implied negative personality traits, the stress group showed enhanced recall for others' implied positive personality traits. This result indicates that post-learning stress affects consolidation of first impressions in a valence-specific manner. We propose that the stress-induced strengthening of memory of others' positive traits forms an important cue for the formation of alliances in stressful conditions. PMID:21298099

Lass-Hennemann, Johanna; Kuehl, Linn K.; Schulz, Andre; Oitzl, Melly S.; Schachinger, Hartmut

2011-01-01

463

Radiodensity evaluation of dental impression materials in comparison to tooth structures  

PubMed Central

In the most recent decades, several developments have been made on impression materials' composition, but there are very few radiodensity studies in the literature. It is expected that an acceptable degree of radiodensity would enable the detection of small fragments left inside gingival sulcus or root canals. Objective The aim of this study was to determine the radiodensity of different impression materials, and to compare them to human and bovine enamel and dentin Material and Methods Twenty-five impression materials, from 5 classes, were studied: addition and condensation silicones, polyether, polysulfides and alginates. Five 1-mm-thick samples of each material and tooth structure were produced. Each sample was evaluated 3 times (N=15), being exposed to x-ray over a phosphor plate of Digora digital system, and radiodensity was obtained by the software Digora for Windows 2.5 Rev 0. An aluminum stepwedge served as a control. Data were subjected to Kruskal- Wallis and Dunn's method (?=0.05). Results Different materials and respective classes had a different behavior with respect to radiodensity. Polysulfides showed high values of radiodensity, comparable to human enamel (p>0.05), but not to bovine enamel (p<0.05). Human dentin was similar only to a heavybody addition silicon material, but bovine dentin was similar to several materials. Generally, heavybody materials showed higher radiodensity than light-body ones (p<0.05). Conclusion Impression materials' radiodensity are influenced by composition, and almost all of them would present a difficult detection against enamel or dentin background in radiographic examinations. PMID:21085802

FONSECA, Rodrigo Borges; BRANCO, Carolina Assaf; HAITER-NETO, Francisco; GONÇALVES, Luciano de Souza; SOARES, Carlos José; CARLO, Hugo Lemes; SINHORETI, Mário Alexandre Coelho; CORRER-SOBRINHO, Lourenço

2010-01-01

464

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

465

Method and apparatus for non-destructive evaluation of composite materials with cloth surface impressions  

NASA Technical Reports Server (NTRS)

A method and related apparatus for nondestructive evaluation of composite materials by determination of the quantity known as Integrated Polar Backscatter, which avoids errors caused by surface texture left by cloth impressions by identifying frequency ranges associated with peaks in a power spectrum for the backscattered signal, and removing such frequency ranges from the calculation of Integrated Polar Backscatter for all scan sites on the composite material is presented.

Madras, Eric I. (inventor)

1995-01-01

466

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. PMID:24841095

Ratner, Kyle G; Dotsch, Ron; Wigboldus, Daniel H J; van Knippenberg, Ad; Amodio, David M

2014-06-01

467

Effect of bite tray impression technique on relocation accuracy in frameless stereotactic radiotherapy  

SciTech Connect

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.

Herbert, Clare E.; Ebert, Martin A.; Barclay, D.; Whittall, David S.; Joseph, David J.; Harper, Chris S.; Spry, Nigel A

2003-03-31

468

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

469

Evaluation of Different Disinfactants on Dimensional Accuracy and Surface Quality of Type IV Gypsum Casts Retrieved from Elastomeric Impression Materials  

PubMed Central

Background: The present study was done to evaluate the dimensional stability and surface quality of Type IV gypsum casts retrieved from disinfected elastomeric impression materials. Materials and Methods: In an in vitro study contaminated impression material with known bacterial species was disinfected with disinfectants followed by culturing the swab sample to assess reduction in level of bacterial colony. Changes in surface detail reproduction of impression were assessed fallowing disinfection. Results: All the three disinfectants used in the study produced a 100% reduction in colony forming units of the test organisms. Conclusion: All the three disinfectants produced complete disinfection, and didn’t cause any deterioration in surface detail reproduction. How to cite the article: Pal PK, Kamble SS, Chaurasia RR, Chaurasia VR, Tiwari S, Bansal D. Evaluation of dimensional stability and surface quality of type IV gypsum casts retrieved from disinfected elastomeric impression materials. J Int Oral Health 2014;6(3):77-81. PMID:25083038

Pal, P K; Kamble, Suresh S; Chaurasia, Ranjitkumar Rampratap; Chaurasia, Vishwajit Rampratap; Tiwari, Samarth; Bansal, Deepak

2014-01-01