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1

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

2

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

3

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

4

“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

5

An alternative impression technique for complete dentures.  

PubMed

This article describes a technique for creating adequate space for an even thickness of polyvinyl siloxane (PVS) impression material at the periphery during complete denture impression making. A PVS border molding material is injected around the borders of a custom tray, a 17-?m-thick stretch wrap film is folded into 4 layers, and a tray-shaped piece slightly larger than the size of the custom tray is placed on the tray covering the borders. After the border molding procedure is completed, the film is removed and the definitive impression completed with a medium-viscosity PVS impression material. PMID:24286641

Yilmaz, Burak; Özçelik, Tuncer Burak

2014-02-01

6

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

7

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

PubMed

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

Naveen, Y G; Patil, Raghunath

2013-03-01

8

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

9

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

10

Siloxane-grafted membranes  

DOEpatents

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

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

1989-01-01

11

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

12

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

13

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

14

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

15

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.

16

Bacteriorhodopsin oriented in polyvinyl alcohol films as an erasable optical storage medium  

Microsoft Academic Search

Films of oriented bacteriorhodopsin have been formed in polyvinyl alcohol with excellent optical quality. Images with high contrast have been impressed and erased on these films. Second-harmonic microscopy has been used to read the image on a bacteriorhodopsin-polyvinyl alcohol film without erasure. The potential of these films for molecular information storage and computation is discussed.

Zhongping Chen; Hiroyuki Takei; Aaron Lewis; Isaiah Nebenzahl

1991-01-01

17

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

18

A new approach to graft siloxanes to alkyds  

Microsoft Academic Search

The effect of oil length of alkyds and substitution of siloxane backbone has been studied for alkyd–siloxane hybrids. A series\\u000a of nine alkyd–siloxane hybrids were synthesized by either varying the oil length of the alkyd or the siloxane backbone substitution.\\u000a Three linseed oil-based alkyds with either a long, medium, or short oil length were grafted with three hydride-terminated\\u000a siloxanes substituted

Ruby Chakraborty; Mrunal Thatte; Mark D. Soucek

2009-01-01

19

TOWARD MINIMALLY ADHESIVE SURFACES UTILIZING SILOXANES  

EPA Science Inventory

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

20

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

21

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

22

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

2014-11-11

23

Virtual First Impressions  

ERIC Educational Resources Information Center

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

Bergren, Martha Dewey

2005-01-01

24

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

25

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

26

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

27

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

28

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

29

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

30

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

31

76 FR 13660 - Polyvinyl Alcohol From Taiwan  

Federal Register 2010, 2011, 2012, 2013, 2014

...731-TA-1088 (Final)] Polyvinyl Alcohol From Taiwan Determination On...reason of imports from Taiwan of polyvinyl alcohol, provided for under subheading...by Commerce that imports of polyvinyl alcohol from Taiwan were being...

2011-03-14

32

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.

33

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

34

PROPERTIES OF LITHIUM-DOPED SILOXANE-PHOSPHONATE CONDUCTING POLYMERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

A series of siloxane copolymers containing pendent phosphonate groups have been prepared and their electrochemical impedance tested. Condensation reactions between methoxy groups of the mononomers produced crosslinked films which were clear, colorless, and stable to air and moisture. The polymers ...

35

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

36

Phrase animation generation reflecting impression of words  

Microsoft Academic Search

This paper proposes a phrase animation generation reflecting impressions of words. The process of generating phrase animations consists of two procedures; impression estimation and animation output. In the former procedure, impressions of an inputted phrase are estimated from impressions of an inputted adjective\\/adjectival verb. That is derived from the number of co-occurrence on web search between the adjective\\/adjectival verb and

Ryou Morita; Takehisa Onisawa

2008-01-01

37

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

Microsoft Academic Search

Siloxanes have been extensively used as additives to modulate surface properties such as surface tension, hydrophobicity\\/hydrophobicity, and adhesion, etc. Although, polydimethyl -siloxane and polydiphenylsiloxane are the most commonly used siloxanes, the properties are at extremes in terms of glass transition temperature and flexibility. It is proposed that the ability to control the properties in between the these extremes can be

Ruby Chakraborty

2008-01-01

38

The Clinical Global Impressions Scale  

PubMed Central

Objective: This paper reviews the potential value in daily clinical practice of an easily applied research tool, the Clinical Global Impressions (CGI) Scale, for the nonresearcher clinician to quantify and track patient progress and treatment response over time. Method: The instrument is described and sample patient scenarios are provided with scoring rationales and a practical charting system. Conclusion: The CGI severity and improvement scales offer a readily understood, practical measurement tool that can easily be administered by a clinician in a busy clinical practice setting. PMID:20526405

Targum, Steven D.

2007-01-01

39

Ecotoxicity of siloxane D5 in soil.  

PubMed

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

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

2012-03-01

40

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

41

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

42

Structural Characterization of New Ferroelectric Liquid-Crystalline Siloxanes  

NASA Astrophysics Data System (ADS)

In a previous paper [1] we reported the structural study of new smectogenic molecules containing three distinct parts, an aromatic core, a central paraffin chain and a siloxane endgroup. In the present paper we report the structural characterization of new ferroelectric liquid crystalline siloxanes containing, in addition to these three parts, a branched aliphatic tail. These low molar mass chiral organosiloxane mesognes and their racemic analogs have been characterized using X-ray diffraction both on powder and oriented samples. The chiral (and achiral) compounds exhibit enantiotropic ferroelectric smectic C^* (or smectic C) mesophases with high tilt angles at low temperatures and over a broad temperatrue range.

Ibn-Elhaj, Mohammed; Skoulios, Antoine; Guillon, Daniel; Newton, Joanna; Hodge, Philip; Coles, Harry J.

1996-02-01

43

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

44

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

45

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

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

2013-01-01

46

21 CFR 872.6570 - Impression tube.  

Code of Federal Regulations, 2012 CFR

...single tooth. The hollow tube is filled with impression material. One end of the tube is sealed with a softened material, such as wax, the remaining end is slipped over the tooth to make the impression. (b) Classification. Class I (general...

2012-04-01

47

21 CFR 872.6570 - Impression tube.  

Code of Federal Regulations, 2011 CFR

...single tooth. The hollow tube is filled with impression material. One end of the tube is sealed with a softened material, such as wax, the remaining end is slipped over the tooth to make the impression. (b) Classification. Class I (general...

2011-04-01

48

Modified functional impression technique for complete dentures  

Microsoft Academic Search

This report describes the use of a removable acrylic resin tray handle that can be easily attached to custom impression trays to produce an improved peripheral sealing zone. This device can be indicated to develop functional impressions for complete dentures using the patient-conducted muscular motion technique. In upper trays, the handle is fixed in the midline with acrylic resin, while

Alexandre Malachias; Cláudia Helena; Valdir Antônio MUGLIA; Carla MORETO

2005-01-01

49

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

Code of Federal Regulations, 2014 CFR

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

2014-07-01

50

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

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

2010-07-01

51

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

Code of Federal Regulations, 2012 CFR

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

2012-07-01

52

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

Code of Federal Regulations, 2013 CFR

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

2013-07-01

53

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

Code of Federal Regulations, 2011 CFR

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

2011-07-01

54

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...Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact...

2011-04-01

55

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...Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact...

2013-04-01

56

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

57

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...Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact...

2012-04-01

58

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

59

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

60

Hydrogen peroxide mechanosynthesis in siloxane-hydrogel contact lenses.  

PubMed

Drug-loaded contact lenses are emerging as the preferred treatment method for several ocular diseases, and efforts are being directed to promote extended and controlled delivery. One strategy is based on delivery induced by environmental triggers. One of these triggers can be hydrogen peroxide, since many platforms based on drug-loaded nanoparticles were demonstrated to be hydrogen-peroxide responsive. This is particularly interesting when hydrogen peroxide is the result of a specific pathophysiological condition. Otherwise, an alternative route to induce drug delivery is here proposed, namely the mechano-synthesis. The present work represents the proof-of-concept of the mechanosynthesis of hydrogen peroxide in siloxane-hydrogel contact lenses as a consequence of the cleavage of siloxane bonds at the interface between the polymer and water in aqueous phase. Their spongy morphology makes contact lenses promising systems for mechanical-to-chemical energy conversion, since the amount of hydrogen peroxide is expected to scale with the interfacial area between the polymer and water. The eyelid pressure during wear is sufficient to induce the hydrogen peroxide synthesis with concentrations which are biocompatible and suitable to trigger the drug release through hydrogen-peroxide-responsive platforms. For possible delivery on demand, the integration of piezoelectric polymers in the siloxane-hydrogel contact lenses could be designed, whose mechanical deformation could be induced by an applied wireless-controlled voltage. PMID:25356999

Tavazzi, Silvia; Ferraro, Lorenzo; Cozza, Federica; Pastori, Valentina; Lecchi, Marzia; Farris, Stefano; Borghesi, Alessandro

2014-11-26

61

Novel Low-Temperature Poss-Containing Siloxane Elastomers  

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

62

Impression cytology of conjunctival melanosis and melanoma.  

PubMed Central

Impression cytology using cellulose acetate paper has been used in various ocular surface disorders as a simple non-invasive diagnostic test. To assess its value in differentiating melanocytic tumours, 24 patients with a range of pigmented lesions of the conjunctiva were examined using this technique. Cytological and histological diagnoses were compared in 23 cases. In 73% of cases impression cytology predicted the histological diagnosis by detection of superficial atypical melanocytes and their proportion relative to benign epithelial cells. This pilot study shows impression cytology to be a useful diagnostic aid in the differentiation of pigmented tumours of the bulbar conjunctiva. Images PMID:1390485

Paridaens, A. D.; McCartney, A. C.; Curling, O. M.; Lyons, C. J.; Hungerford, J. L.

1992-01-01

63

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

64

21 CFR 872.3670 - Resin impression tray material.  

Code of Federal Regulations, 2010 CFR

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

2010-04-01

65

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

66

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

NASA Astrophysics Data System (ADS)

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

Chakraborty, Ruby

67

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

68

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

Microsoft Academic Search

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

Mirzan T Razzak; Darmawan Darwis; Zainuddin; Sukirno

2001-01-01

69

The effect of polyvinyl alcohol and polyvinyl pyrrolidone on diffusion artifacts in lactate dehydrogenase histochemistry  

Microsoft Academic Search

The effect of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP), alone and in combination, on diffusion artifacts in histochemical incubations has been investigated using LDH as model enzyme. By measuring the amount of formazan in the medium at the end of the incubation it has been shown that both substances, but especially PVA, are effective in limiting diffusion. The significance

Hans A. Dahl; Svein Ivar Mellgren

1970-01-01

70

Group impressions as dynamic configurations: the tensor product model of group impression formation and change.  

PubMed

Group impressions are dynamic configurations. The tensor product model (TPM), a connectionist model of memory and learning, is used to describe the process of group impression formation and change, emphasizing the structured and contextualized nature of group impressions and the dynamic evolution of group impressions over time. TPM is first shown to be consistent with algebraic models of social judgment (the weighted averaging model; N. Anderson, 1981) and exemplar-based social category learning (the context model; E. R. Smith & M. A. Zárate, 1992), providing a theoretical reduction of the algebraic models to the present connectionist framework. TPM is then shown to describe a common process that underlies both formation and change of group impressions despite the often-made assumption that they constitute different psychological processes. In particular, various time-dependent properties of both group impression formation (e.g., time variability, response dependency, and order effects in impression judgments) and change (e.g., stereotype change and group accentuation) are explained, demonstrating a hidden unity beneath the diverse array of empirical findings. Implications of the model for conceptualizing stereotype formation and change are discussed. PMID:11089411

Kashima, Y; Woolcock, J; Kashima, E S

2000-10-01

71

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

SciTech Connect

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

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

2013-10-15

72

[Changing the collective impression of palliative care].  

PubMed

The general public and health professionals may have a mistaken impression of palliative care and the Leonetti law. Thanks to training and information on the measures taken by the government with regard to the development of palliative care, the palliative culture is gradually becoming integrated into healthcare structures and mentalities. PMID:22003790

de la Brière, Alice; Tocheport, Pascale

2011-09-01

73

Project MATCH Client Impressions About Alcoholics Anonymous  

Microsoft Academic Search

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

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

2000-01-01

74

RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol  

E-print Network

RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol: interfacial layer and bulk:1 and 14 nm for 50:1). The presence of polyvinyl alcohol (PVA) limits the particle growth (15 nm for 20

Guo, John Zhanhu

75

Preparation and characterization of a siloxane containing bismaleimide  

NASA Technical Reports Server (NTRS)

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

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

1984-01-01

76

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

77

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

78

Leaf Impressions: A Model for Carbonization  

NSDL National Science Digital Library

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

Greb, Stephen

79

Radiolysis of tetrazolium salts in polyvinyl alcohol  

SciTech Connect

The radiation chemical yields of formazans were measured in binary systems containing polyvinyl alcohol and tetrazolium salts as additives; it was established that they are more than half of the yields of radicals in pure polyvinyl alcohol. The ESR spectra of the indicated systems were measured at various temperatures, and the relative changes in the radical concentrations were determined. It was suggested that the increase in the concentration of single radicals at T > 400 K is due to the participation of radical pairs in the reaction. 15 refs., 4 figs., 1 tab.

Kriminskaya, Z.K.; Ginzburg, S.F.; Molin, A.A.

1992-01-01

80

Polyvinyl alcohol battery separator containing inert filler  

SciTech Connect

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

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

1981-06-01

81

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

82

Burger or yogurt? Indulgent consumption in impression management contexts.  

PubMed

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

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

2014-10-01

83

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

Microsoft Academic Search

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

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

2010-01-01

84

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

PubMed

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

Tran, Tri Manh; Kannan, Kurunthachalam

2015-04-01

85

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

PubMed

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

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

2015-02-01

86

Polyvinyl Alcohol Particle Size and Suspension Characteristics  

Microsoft Academic Search

PURPOSE: To evaluate the size and shape of commercially available polyvinyl alcohol (PVA) particles and to determine whether they change in size when suspended in nonionic contrast and in a solution of nonionic contrast and absolute alcohol. METHODS: The two-dimensional area and the long and short axis of PVA particles from several different vendors were measured using a light microscope

Colin P. Derdeyn; Christopher J. Moran; DeWitte T. Cross; Hans H. Dietrich; Ralph G. Dacey

87

Observations and impressions from lunar orbit  

NASA Technical Reports Server (NTRS)

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

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

1972-01-01

88

Multiband Impressions of Active Galactic Nuclei  

NASA Astrophysics Data System (ADS)

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

Marscher, Alan P.

89

Impression cytology of the ocular surface  

PubMed Central

Impression cytology refers to the application of a cellulose acetate filter to the ocular surface to remove the superficial layers of the ocular surface epithelium. These cells can then be subjected to histological, immunohistological, or molecular analysis. Proper technique is essential as the number of cells sampled can vary considerably. Generally two to three layers of cells are removed in one application but deeper cells can be accessed by repeat application over the same site. Applications for impression cytology include diagnosing a wide range of ocular surface disorders, documenting sequential changes in the conjunctival and corneal surface over time, staging conjunctival squamous metaplasia, and monitoring effects of treatment. It is also a useful investigational tool for analysing ocular surface disease with immunostaining and DNA analysis. It is non-invasive, relatively easy to perform, and yields reliable information about the area sampled with minimal discomfort to the patient. Major ophthalmic centres should develop and introduce this technique into routine clinical practice. This is best achieved with a team approach including the ophthalmologist, pathologist, microbiologist, and the immunologist. PMID:16299150

Singh, R; Joseph, A; Umapathy, T; Tint, N L; Dua, H S

2005-01-01

90

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

91

First impressions of the comet drilling problem  

NASA Astrophysics Data System (ADS)

Preliminary impressions gained from the workshop by someone with no prior knowledge of comets or space technology are presented. Ideas on the composition and density of comet material are suggested as needing refinement in order to give the drill designer a fair chance of success. Comments on the subsurface sampling, power allocation, static force and torque for drilling, design limits for drilling rate, materials for cutting tools clearing drill cuttings, anchoring the lander, positioning the core drill, inertial drilling systems and testing are given. The influence of the drilling and sampling needs on the basic design of the lander and return capsule are called into question. A warning of possible flaws in the comments due to insufficient understanding of the problem is given.

Mellor, Malcom

1989-12-01

92

Dimensional stability ofautoclave sterilised addition cured impressions and trays.  

PubMed

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

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

2014-03-01

93

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

PubMed

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

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

2009-01-01

94

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

95

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

PubMed Central

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

Riemer, Hila; Shavitt, Sharon

2012-01-01

96

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

PubMed

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

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

2014-04-01

97

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

98

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

99

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

Federal Register 2010, 2011, 2012, 2013, 2014

...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

100

Electrochemical study of ferrocene intercalated vanadium pentoxide xerogel/polyvinyl alcohol composite films: Application  

E-print Network

Electrochemical study of ferrocene intercalated vanadium pentoxide xerogel/polyvinyl alcohol film based on ferrocene intercalated vanadium pentoxide xerogel/polyvinyl alcohol (FeCp2/VXG biosensor; Photocrosslinkable styrylpyrid- inium modified polyvinyl alcohol 1. Introduction Sol

Trikalitis, Pantelis N.

101

75 FR 38079 - Postponement of Preliminary Determination of Antidumping Duty Investigation: Polyvinyl Alcohol...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Antidumping Duty Investigation: Polyvinyl Alcohol From Taiwan AGENCY: Import...antidumping duty investigation on polyvinyl alcohol from Taiwan. See Initiation...Anti-Dumping Duty Investigation: Polyvinyl Alcohol From Taiwan, 69 FR...

2010-07-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

103

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

E-print Network

Mediterranean Impressions FREE AIRFARE*2-FOR-1 CRUISE FARES BARCELONA · MARSEILLE/PROVENCE · MONTE, Mediterranean Summer · Culinary Producer on over 250 cooking shows including four series with respected chef Mediterranean Impressions S1 PRSRTSTD U.S.POSTAGE PAID PERMIT#32322 TWINCITIES,MN SyracuseUniversity Goldstein

Mather, Patrick T.

104

Effects of Inconsistent Behaviors on Person Impressions: A Multidimensional Study.  

ERIC Educational Resources Information Center

Examined effects of unexpected behavioral information on person impressions. Inconsistency was manipulated with respect to Implicit Personality Theory. Found that behaviors with inconsistent evaluation implications did not affect impressions and that effects of inconsistent information depended on dimension of contrast, valence of initial…

Vonk, Roos

1995-01-01

105

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

106

>Cognitive complexity and impression formation in informal social interaction  

Microsoft Academic Search

While awaiting the arrival of the experimenter, pairs of subjects participated in ten minutes of spontaneous casual interaction. The impression which each formed of the other was assessed. Analyses of these impressions compared subjects differing in initial level of cognitive complexity. High complexity subjects, in comparison with noncomplex subjects, formed more differentiated, more abstract, more highly organized, and less evaluatively

Jesse G. Delia; Ruth Anne Clark; David E. Switzer

1974-01-01

107

Using double-poured alginate impressions to fabricate bleaching trays.  

PubMed

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

Haywood, V B; Powe, A

1998-01-01

108

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

109

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

110

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

111

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

112

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

PubMed

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

Ruan, Xiuxiu; Zhu, Lizhong; Chen, Baoliang

2008-11-01

113

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

114

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

115

Process for the extrusion of compositions comprising polypropylene, polyvinyl alcohol and a polypropylene-polyvinyl alcohol adhesive  

SciTech Connect

This patent describes a process for extruding a composition comprising polyvinyl alcohol, a polypropylene-polyvinyl alcohol adhesive and a plypropylene prepared with a high activity polymerization catalyst. The improvement consists of utilizing polypropylene having from about 50 to about 5000 ppm by weight of hydrotalcite incorporated therein to substantially eliminate gel formation.

Derrick, W.E.

1989-04-18

116

Accuracy of stone casts obtained by different impression materials.  

PubMed

Several impression materials are available in the Brazilian marketplace to be used in oral rehabilitation. The aim of this study was to compare the accuracy of different impression materials used for fixed partial dentures following the manufacturers' instructions. A master model representing a partially edentulous mandibular right hemi-arch segment whose teeth were prepared to receive full crowns was used. Custom trays were prepared with auto-polymerizing acrylic resin and impressions were performed with a dental surveyor, standardizing the path of insertion and removal of the tray. Alginate and elastomeric materials were used and stone casts were obtained after the impressions. For the silicones, impression techniques were also compared. To determine the impression materials' accuracy, digital photographs of the master model and of the stone casts were taken and the discrepancies between them were measured. The data were subjected to analysis of variance and Duncan's complementary test. Polyether and addition silicone following the single-phase technique were statistically different from alginate, condensation silicone and addition silicone following the double-mix technique (p < or = .05), presenting smaller discrepancies. However, condensation silicone was similar (p > or = .05) to alginate and addition silicone following the double-mix technique, but different from polysulfide. The results led to the conclusion that different impression materials and techniques influenced the stone casts' accuracy in a way that polyether, polysulfide and addition silicone following the single-phase technique were more accurate than the other materials. PMID:19148382

Faria, Adriana Cláudia Lapria; Rodrigues, Renata Cristina Silveira; Macedo, Ana Paula; Mattos, Maria da Gloria Chiarello de; Ribeiro, Ricardo Faria

2008-01-01

117

A rare allergy to a polyether dental impression material.  

PubMed

Polyether impression materials have been used in dentistry for more than 40 years. Allergic reactions to these materials such as reported in the 1970s ceased after replacement of a catalyst. Very recently, however, patients have started to report symptoms that suggest a new allergic reaction from polyether impression materials. Here, we report on the results of allergy testing with polyether impression materials as well as with its components. Eight patients with clinical symptoms of a contact allergy (swelling, redness or blisters) after exposure to a polyether impression material were subjected to patch tests, two of them additionally to a prick test. A further patient with atypical symptoms of an allergy (nausea and vomiting after contact with a polyether impression material in the oral cavity) but with a history of other allergic reaction was also patch tested. The prick tests showed no immediate reactions in the two patients tested. In the patch tests, all eight patients with typical clinical symptoms showed positive reactions to the mixed polyether impression materials, to the base paste or to a base paste component. The patient with the atypical clinical symptoms did not show any positive patch test reactions. Polyether impression materials may evoke type IV allergic reactions. The causative agent was a component of the base paste. In consideration of the widespread use of this impression material (millions of applications per year) and in comparison to the number of adverse reactions from other dental materials, the number of such allergic reactions is very low. In very scarce cases, positive allergic reactions to polyether impression materials are possible. PMID:21947905

Mittermüller, Pauline; Szeimies, Rolf-Markus; Landthaler, Michael; Schmalz, Gottfried

2012-08-01

118

A Randomised Controlled Trial of complete denture impression materials  

PubMed Central

Objectives There is continuing demand for non-implant prosthodontic treatment and yet there is a paucity of high quality Randomised Controlled Trial (RCT) evidence for best practice. The aim of this research was to provide evidence for best practice in prosthodontic impressions by comparing two impression materials in a double-blind, randomised, crossover, controlled, clinical trial. Methods Eighty-five patients were recruited, using published eligibility criteria, to the trial at Leeds Dental Institute, UK. Each patient received two sets of dentures; made using either alginate or silicone impressions. Randomisations determined the order of assessment and order of impressions. The primary outcome was patient blinded preference for unadjusted dentures. Secondary outcomes were patient preference for the adjusted dentures, rating of comfort, stability and chewing efficiency, experience of each impression, and an OHIP-EDENT questionnaire. Results Seventy-eight (91.8%) patients completed the primary assessment. 53(67.9%) patients preferred dentures made from silicone impressions while 14(17.9%) preferred alginate impressions. 4(5.1%) patients found both dentures equally satisfactory and 7 (9.0%) found both equally unsatisfactory. There was a 50% difference in preference rates (in favour of silicone) (95%CI 32.7–67.3%, p < 0.0001). Conclusion There is significant evidence that dentures made from silicone impressions were preferred by patients. Clinical significance Given the strength of the clinical findings within this paper, dentists should consider choosing silicone rather than alginate as their material of choice for secondary impressions for complete dentures. Trial Registration: ISRCTN 01528038.?? This article forms part of a project for which the author (TPH) won the Senior Clinical Unilever Hatton Award of the International Assocation for Dental Research, Capetown, South Africa, June 2014. PMID:24995473

Hyde, T.P.; Craddock, H.L.; Gray, J.C.; Pavitt, S.H.; Hulme, C.; Godfrey, M.; Fernandez, C.; Navarro-Coy, N.; Dillon, S.; Wright, J.; Brown, S.; Dukanovic, G.; Brunton, P.A.

2014-01-01

119

A technique for impressing the severely resorbed mandibular edentulous ridge.  

PubMed

Patients presenting with severe resorption of the residual alveolar ridges are relatively common today in both private practices and teaching institutions. The severely resorbed mandibular ridge is more challenging to impress than is the maxillary ridge. Accurately capturing the denture-bearing surface in its entirety is crucial to providing the patient with a functionally successful prosthesis. This article presents a technique to overcome the difficulties encountered in impressing the severely resorbed mandibular ridge using elastomeric impression materials and a modified special custom tray. PMID:22372876

Chandrasekharan, Nair K; Kunnekel, Ashish T; Verma, Mahesh; Gupta, Rajiv K

2012-04-01

120

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

NASA Astrophysics Data System (ADS)

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

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

2001-07-01

121

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

122

Coping with stereotype threat: Denial as an impression management strategy  

E-print Network

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

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

2005-01-01

123

Impression management and food intake. Current directions in research.  

PubMed

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

Vartanian, Lenny R

2015-03-01

124

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

125

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

PubMed

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

Surita, Sharon C; Tansel, Berrin

2015-03-01

126

[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

127

Fabrication of polyvinyl alcohol coated polystyrene shells  

SciTech Connect

Glass shells have been used traditionally as the deuterium--tritium fuel container for direct-drive laser fusion experiments because of their convenience and availability, but lower-Z fuel containers have superior implosion characteristics and diagnostic possibilities. Unfortunately, polymers such as polystyrene (PS) that produce shells easily have very high permeabilities so require cryogenics to retain fuel, and impermeable polymers such as polyvinyl alcohol (PVA) are difficult to make into high-quality shells. We have developed improved methods of making PS shells with diameters from 0.2 to 0.7 mm and coating them with a 3-..mu..m layer of PVA to obtain the advantages of both. Both the PS shells and the PVA coating are made in drop towers using gas-stripped nozzles. Details of the procedures and product quality are discussed.

Burnham, A.K.; Grens, J.Z.; Lilley, E.M.

1987-11-01

128

Polyvinyl alcohol membranes as alkaline battery separators  

SciTech Connect

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

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

1982-01-01

129

Effect of gamma radiation on gelation in polyvinyl alcohol solutions  

NASA Astrophysics Data System (ADS)

The radiation effect of various pH values on polyvinyl alcohol aqueous solutions and on organic solutions, as well as those of scavengers in the aqueous solutions were examined. The gelation dose R g changes with various pH values; a small amount of free radical scavengers in the system inhibits the crosslinking of polymer molecules and raises R g. Degradation of polyvinyl in alcohol dimethyl sulfone solution occurs after irradiation, providing a mechanism of radiation-induced crosslinking of polyvinyl alcohol aqueous solutions is initiated by the transient species H and OH of water, but not the species e -aq.

Wenxiu, Chen; Huaying, Bao; Manwei, Zhang

130

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

PubMed Central

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

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

2011-01-01

131

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

132

Effect of impression coping and implant angulation on the accuracy of implant impressions: an in vitro study  

PubMed Central

PURPOSE The purpose of this study was to compare the accuracy of the implant master cast according to the type (pick-up, transfer) and the length (long, short) of the impression copings. MATERIALS AND METHODS The metal master cast was fabricated with three internal connection type implant analogs (Osstem GS III analog), embedded parallel and with 10° of mesial angulation to the center analog. Four types of impression coping were prepared with different combinations of types (transfer, pick-up) and lengths (long, short) of the coping. The impressions were made using vinyl polysiloxane (one step, heavy + light body) with an individual tray, and 10 impressions were made for each group. Eventually, 40 experimental casts were produced. Then, the difference in the distance between the master cast and the experimental cast were measured, and the error rate was determined. The analysis of variance was performed using the SPSS (v 12.0) program (? = .05), and the statistical significance was set at P < .05. RESULTS The ANOVA showed that the pick-up type impression coping exhibited a significantly lower error rate than the transfer type. However, no significant difference was observed with respect to the length of the impression coping. Additionally, no significant difference was observed between the parallel and mesial angulated groups. CONCLUSION Within the limitations of this study, the pick-up type impression coping exhibited a more accurate implant master cast than the transfer type in parallel group. The accuracy of the implant master cast did not differ for different lengths of impression coping of at least 11 mm. Additionally, the accuracy of the implant cast was not different for the parallel and 10° mesial angulated groups. PMID:21264191

Jo, Si-Hoon; Kim, Kyoung-Il; Seo, Jae-Min; Song, Kwang-Yeob; Park, Ju-Mi

2010-01-01

133

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

134

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

135

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

DOEpatents

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

Besmann, Theodore M

2014-01-21

136

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

PubMed

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

Yomaru, H; Ohtake, H; Yokozuka, S

1989-10-01

137

Dynamic surface tension and adsorption kinetics of a siloxane dicephalic surfactant  

NASA Astrophysics Data System (ADS)

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

Zhang, Dianlong; Qu, Wenshan; Li, Zhe

2015-02-01

138

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

139

Perylenediimide functionalized bridged-siloxane nanoparticles for bulk heterojunction organic photovoltaics  

NASA Astrophysics Data System (ADS)

Perylenediimide functionalized bridged siloxane nanoparticles were prepared by direct hydrolysis and condensation of a perylenediimide silane precursor in the presence of a catalytic amount of tetraethoxysilane (TEOS). The sizes of the particles were controlled by adjusting organotrialkoxysilane, base, and TEOS concentrations. Using this modified Stöber method, we were able to incorporate a higher load of organic content (~70%) into the siloxane core compared to typical organically modified Stöber silica nanoparticles. The size, shape, and surface morphology of these functionalized particles were visualized using transmission electron microscopy. Their compositions were confirmed by FTIR, thermogravimetric analysis, and elemental analysis. The photovoltaic performance of these nanohybrids in the poly(3-hexylthiophene) polymer matrix was evaluated. The device made from a sample annealed at 150 °C showed reasonably good photovoltaic performance with a power conversion efficiency of 1.56% under standard test conditions of AM 1.5G spectra at an illumination intensity of 100 mW cm-2.Perylenediimide functionalized bridged siloxane nanoparticles were prepared by direct hydrolysis and condensation of a perylenediimide silane precursor in the presence of a catalytic amount of tetraethoxysilane (TEOS). The sizes of the particles were controlled by adjusting organotrialkoxysilane, base, and TEOS concentrations. Using this modified Stöber method, we were able to incorporate a higher load of organic content (~70%) into the siloxane core compared to typical organically modified Stöber silica nanoparticles. The size, shape, and surface morphology of these functionalized particles were visualized using transmission electron microscopy. Their compositions were confirmed by FTIR, thermogravimetric analysis, and elemental analysis. The photovoltaic performance of these nanohybrids in the poly(3-hexylthiophene) polymer matrix was evaluated. The device made from a sample annealed at 150 °C showed reasonably good photovoltaic performance with a power conversion efficiency of 1.56% under standard test conditions of AM 1.5G spectra at an illumination intensity of 100 mW cm-2. Electronic supplementary information (ESI) available. See DOI: 10.1039/c2nr30538k

Rathnayake, Hemali; Binion, Jenna; McKee, Aaron; Scardino, Debra Jo; Hammer, Nathan I.

2012-07-01

140

Mean-square optical anisotropies and molar Kerr constants of cyclic and linear dimethyl siloxanes  

Microsoft Academic Search

Mean-square optical anisotropies, ??2?0, and mean molar Kerr constants, ?mK?0, have been calculated for cyclic dimethyl siloxane oligomers having from n=8 to n=20 skeletal bonds. Stringent criteria were used to select ‘‘cyclic’’ conformations of the equivalent open chains based on the relative orientations and rotational states of the terminal bonds. The values obtained for the cyclic oligomers are compared with

Stephen J. Mumby; Martin S. Beevers

1985-01-01

141

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

142

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2012 CFR

...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.270 Poly(vinyl fluoride)...

2012-04-01

143

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2011 CFR

...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.270 Poly(vinyl fluoride)...

2011-04-01

144

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2013 CFR

...DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.270 Poly(vinyl fluoride)...

2013-04-01

145

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2014 CFR

...and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: ADHESIVES AND COMPONENTS OF COATINGS Substances for Use as Components of Coatings § 175.270 Poly(vinyl fluoride)...

2014-04-01

146

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

147

Preparation of poly(vinyl formal) of high acetalization  

Microsoft Academic Search

Poly(vinyl alcohol) (PVA) can be dissolved in a non-aqueous medium in the presence of catalytic concentrations of C2H5ONO2.DMSO(EN.DMSO). Poly(vinyl formal) (PVF) of 90% acetalization was prepared by acid catalysed homogeneous formalization of PVA of molecular weight 14 000 with paraformaldehyde. The formation of the formal was confirmed from the i.r. and 1H n.m.r. spectra. The molecular weight of the polymer

P. Chetri; N. N. Dass

1997-01-01

148

Effect of Time on Gypsum-Impression Material Compatibility  

NASA Astrophysics Data System (ADS)

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

Won, John Boram

149

Forming impressions: effects of facial expression and gender stereotypes.  

PubMed

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

Hack, Tay

2014-04-01

150

Hydrothermal carbonization of poly(vinyl chloride).  

PubMed

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

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

2015-01-01

151

Heat resistance poly(vinyl alcohol) hydrogel  

NASA Astrophysics Data System (ADS)

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

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

1995-08-01

152

Piezoresistive Properties of Polyvinyl Chloride Composites  

NASA Astrophysics Data System (ADS)

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

Toprakci, Hatice Aylin Karahan

153

Does immediate dentin sealing influence the polymerization of impression materials?  

PubMed Central

Objectives: The objective of the following study is to evaluate the interaction between the resin materials used in immediate dentin sealing (IDS) techniques and impression materials with two different techniques to eliminate the oxygen-inhibition layer. Materials and Methods: The occlusal dentin surface of 35 human molars was exposed. The teeth were used in two Groups: Group 1 – Impression with Express XT; Group 2 – Impression with Impregum. Groups 1 and 2 were divided into 14 subgroups: Groups 1a and 2a – Control groups; 1b and 2b – IDS with Clearfil SE Bond (CSE); 1c and 2c – IDS with CSE + additional polymerization with glycerin jelly; 1d and 2d – IDS with CSE + alcohol; 1e and 2e – IDS with CSE and Protect Liner F (PLF); 1f and 2f – IDS with CSE and PLF + additional polymerization with glycerin jelly; and 1g and 2g – IDS with CSE and PLF + alcohol. Five teeth were used in each experimental group, and the tooth surface was photographed using a digital camera. Results: Small quantity of unpolymerized impression material remained attached to the CSE or to the PLF in Groups 1b and 1e. Groups 1c and 1d prevented the interaction. Small quantity of polymerized impression material remained attached to the CSE or to the PLF for Groups 2b and 2e. The same interaction was observed for Groups 2c and 2d. For Groups 2c and 2f, no interactions were observed. Conclusion: Resin materials interacted with impression materials. The application of glycerin jelly and alcohol prevented the interaction of CSE with Express XT and PLF with Impregum; however, these treatments were not completely effective in preventing the interaction of CSE with Impregum and PLF with Express XT. PMID:25202218

Ghiggi, Paula Cristine; Steiger, Arno Kieling; Marcondes, Maurem Leitão; Mota, Eduardo Gonçalves; Burnett, Luiz Henrique; Spohr, Ana Maria

2014-01-01

154

Testing the incremental utility of the negative impression-positive impression differential in detecting simulated personality assessment inventory profiles.  

PubMed

The usefulness of multiscale inventories depends on their ability to evaluate response styles effectively, such as fake-bad (feigning) and fake-good (defensiveness) profiles. The current investigation combined validity data across clinical, nonclinical, and simulating samples to evaluate the usefulness of the Personality Assessment Inventory (PAI) negative impression (NIM)-positive impression (PIM) difference score to detect simulated profiles. In general, its effect sizes were not appreciably different from those afforded by NIM and PIM alone. Likewise, its incremental contributions in logistic regression were minimal. These results do not support the routine use of a NIM-PIM difference score in detecting response styles with the PAI. PMID:18302214

Hopwood, Christopher J; Talbert, Christy A; Morey, Leslie C; Rogers, Richard

2008-03-01

155

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

156

The Impressive Power of Stopwatches Franck Cassez1  

E-print Network

The Impressive Power of Stopwatches Franck Cassez1 and Kim Larsen2 1 IRCCyN/CNRS UMR 6597, France of this class of automata, and show as a main result that any finite or infinite timed language accepted are two-fold: firstly, it shows that the seemingly minor upgrade from timed automata to stopwatch automata

David, Alexandre

157

Modeling first impressions from highly variable facial images  

PubMed Central

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

2014-01-01

158

First Impressions: Gait Cues Drive Reliable Trait Judgements  

ERIC Educational Resources Information Center

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.…

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

2012-01-01

159

Making an Impression: YA Authors and Their Influential Teachers  

ERIC Educational Resources Information Center

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

Eisenbach, Brooke; Kaywell, Joan F.

2013-01-01

160

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

161

Cross-Cultural Impression Management: A Cultural Knowledge Audit Model  

ERIC Educational Resources Information Center

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

Spong, Abigail; Kamau, Caroline

2012-01-01

162

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

Federal Register 2010, 2011, 2012, 2013, 2014

...International Trade Administration [A-583-841] Polyvinyl Alcohol From Taiwan: Correction to Notice of Opportunity...administrative review of the antidumping duty order on polyvinyl alcohol from Taiwan. See Antidumping or Countervailing...

2012-03-09

163

Radiation-chemical preparation of poly(vinyl alcohol) hydrogels  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

164

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

165

Inspired by nature: an exploration of biocatalyzed siloxane bond formation and cleavage.  

PubMed

The intricate siliceous architectures of diatom species have inspired our exploration of biosilicification. In vitro studies of natural systems within the area of silica biosynthesis are complicated. Previous studies, which included biomimetic approaches, often failed to recognize the chemistry of silicic acid and its analogues. To better understand the role of various proteins in the biosilicification process, recent studies have been conducted to test the ability of enzymes to catalyze the formation and cleavage of siloxane bonds. Notably, biocatalysis at silicon was observed. Further understanding of the biotransformation strategy in the design and synthesis of structurally complex materials would be beneficial. PMID:16002277

Brandstadt, Kurt F

2005-08-01

166

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

DOEpatents

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

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

1988-01-01

167

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

168

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

DOEpatents

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

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

1988-11-01

169

Plasma-Enhanced Co-Polymerization of Organo-siloxane and Hydrocarbon for Low-k/Cu Interconnects  

NASA Astrophysics Data System (ADS)

A plasma-enhanced co-polymerization technique was developed for low-k/Cu damascene integration on 300 mm wafers. This technique enables us to control dielectric film properties by introducing organo-siloxane and hydrocarbon into a He-plasma. The growth rate of the low-k film derived from divinyl siloxane-benzocyclobutene (DVS-BCB) as a matrix monomer is increased by adding C2H2 as a deposition acceleration monomer and the Young’s modulus was enhanced by adding diisopropenylbenzene (DIPB) or divinylbenzene (DVB) as a reinforcement monomer. Cu damascene interconnects with plasma polymerized low-k films were successfully fabricated on 300 mm wafers.

Kawahara, Jun; Nakano, Akinori; Kunimi, Nobutaka; Kinoshita, Keizo; Hayashi, Yoshihiro; Ishikawa, Akira; Seino, Yutaka; Ogata, Tetsuro; Sonoda, Yuzuru; Yoshino, Takenobu; Goto, Takashi; Takada, Syozo; Miyoshi, Hidenori; Matsuo, Hisanori; Kikkawa, Takamaro

2007-07-01

170

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

171

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.

172

An Anthropomorphic Polyvinyl Alcohol Triple-Modality Brain Phantom based on  

E-print Network

An Anthropomorphic Polyvinyl Alcohol Triple-Modality Brain Phantom based on Colin27 Sean Jy phantom from polyvinyl alcohol cryogel (PVA-C) for validation of image processing methods for segmentation elected to use for constructing this phantom is polyvinyl alcohol. (a) (b) (c) (d) Fig. 1. Two views

Paris-Sud XI, Université de

173

Some effects of disinfecting solutions on the properties of alginate impression material and dental stone.  

PubMed

The study investigated the effect of two disinfecting solutions on one brand of alginate impression material and dental stone. Control impressions were immersed in water for equivalent periods and the effect of storage of impressions after disinfection or control immersion in water was also investigated. There were no significant dimensional changes in impressions poured after one hour. All impressions stored for 16 hours before pouring showed significant dimensional changes. Mixing dental stone with one disinfectant caused a significant softening of the cast. It is strongly recommended that all impressions are thoroughly rinsed with water after disinfection to prevent incorporation of disinfectant in the cast. PMID:12192949

Boden, J; Likeman, P; Clark, R

2001-01-01

174

Crack formation in polyvinyl chloride coatings on underground pipes  

Microsoft Academic Search

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

B. I. Borisov; CHLORIDE COATINGS

1975-01-01

175

Immobilization of enzymes in photochemically cross-linked polyvinyl alcohol  

Microsoft Academic Search

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

Thomas Uhlich; Mathias Ulbricht; Georg Tomaschewski

1996-01-01

176

Biodegradation of a polyvinyl alcohol-starch blend plastic film  

Microsoft Academic Search

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

Tomonori Ishigaki; Yasunori Kawagoshi; Michihiko Ike; Masanori Fujita

1999-01-01

177

Review of the oral toxicity of polyvinyl alcohol (PVA)  

Microsoft Academic Search

Polyvinyl alcohols (PVA) (CAS no. 9002-89-5) are synthetic polymers used in a wide range of industrial, commercial, medical and food applications. The purpose of this review, this critical evaluation of the available information on PVA, is to support the safety of PVA as a coating agent for pharmaceutical and dietary supplement products. All the available information on PVA gleaned from

C. C DeMerlis; D. R Schoneker

2003-01-01

178

Vaginal Absorption of Polyvinyl Alcohol in Fischer 344 Rats  

Microsoft Academic Search

Polyvinyl alcohol (PVA) is a polymer with a wide range of molecular weights and uses. Recently, low molecular weight formulations of PVA have been used as components of contraceptive products designed for intravaginal administration in human females. Previous studies in animals have determined that little or no absorption of PVA occurs from the gastrointestinal (GI) tract. However, there is some

J. M. Sanders; H. B. Matthews

1990-01-01

179

Immobilization of microbial cells using polyvinyl alcohol (PVA) — polyacrylamide gels  

Microsoft Academic Search

A novel cell immobilization technique is developed in which polyvinyl alcohol is crosslinked with boric acid with addition of an acrylamide as a polymerizing agent. The presence of the polymerizing agent overcomes the problem of swelling of PVA gels in aqueous solution. The new immobilization method was used to entrap a phenol-degrading microorganism, a species of Pseudomonas. Phenol was successfully

Wang Jianlong; Hou Wenhua; Qian Yicr

1995-01-01

180

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

Code of Federal Regulations, 2010 CFR

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

2010-04-01

181

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

182

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

PubMed

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

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

2013-11-01

183

Wear effects on microscopic morphology and hyaluronan uptake in siloxane-hydrogel contact lenses.  

PubMed

The purpose of this study was a comparison between new and worn siloxane-hydrogel contact lenses in terms of microscopic structure, surface morphology, and loading of hyaluronan. The analyses were performed by scanning electron microscopy, with the support of the freeze-drying technique, and by fluorescence confocal microscopy. Along the depth profile of new lenses, a thin porous top layer was observed, which corresponds to the region of hyaluronan penetration inside well-defined channels. The time evolution was followed from one day to two weeks of daily wear, when a completely different scenario was found. Clear experimental evidence of a buggy surface was observed with several crests and regions of swelling, which could be filled by the hyaluronan solution. The modifications are attributed to the progressive relaxation of the structure of the polymeric network. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2014. PMID:25251841

Tavazzi, Silvia; Tonveronachi, Martina; Fagnola, Matteo; Cozza, Federica; Ferraro, Lorenzo; Borghesi, Alessandro; Ascagni, Miriam; Farris, Stefano

2014-09-23

184

Improved resolution of natural diacylglycerols by gas-liquid chromatography on polar siloxanes.  

PubMed

A new cyanoalkylphenylsiloxane (SILAR 5CP) liquid phase is shown to possess sufficient polarity to permit improved GC separations of natural diacylglycerols based on unsaturation and positional placement of fatty acids as well as on molecular weight, which was previously possible only on ethylene glycol succinate polyesters. Unlike the polyesters, the polar siloxane polymer has moderate thermal stability and provides GC columns which can be used for several months without replacing the packing. The GC analyses were made with conventional columns containing 3% SILAR 5CP on Gas Chrom Q at 270 degrees C isothermally. The diacylglycerols were chromatographed as the TMS ethers. Excellent seperations were obtained for the 1,2(2,3)- and 1,3-diacyglycerols derived from corn, linseed, peanut and cod liver oils and for the 1,2-diacyl-sn-glycerols from hepatic glycerophospholipids. PMID:1150850

Myher, J J; Kuksis, A

1975-03-01

185

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

PubMed

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

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

2015-03-21

186

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

187

Three dimensional visualization and comparison of impressions on fired bullets.  

PubMed

Currently, optical devices, such as microscopes and CCD cameras, are utilized for identification of bullets and tool marks in the field of forensic science. While these optical methods are easily manageable and effective, they are under great influence of illumination condition. In other words, appearances of striations through these optical devices have possibility to be changed by lighting condition. Besides these appearance-based approaches, we can utilize three dimensional (3D) geometric data of tool marks that are free from lighting condition. In this study, we focused on 3D geometric data of landmark impressions on fired bullets for identification. We obtained the 3D surface data of tool marks by a confocal microscope and reconstructed virtual impressions on a PC monitor from the geometric data. Furthermore, the 3D data are exploited to numerical matching of two surface shapes. We also visualized the difference of two shapes. In order to do this, two surface models are aligned automatically. In this process, pairings of correspondent points on both surfaces are determined. Distance analysis between these pairs leads to a shape comparison. Since comparison results are visualized, they are intuitive and easily perceptive. PMID:15036444

Banno, Atsuhiko; Masuda, Tomohito; Ikeuchi, Katsushi

2004-03-10

188

Chemical enhancement of soil based footwear impressions on fabric.  

PubMed

This study investigates the enhancement of footwear impressions prepared with soils from different locations on a variety of fabric surfaces with different morphology. Preliminary experiments using seventeen techniques were carried out and the best responding reagents were evaluated further. Results indicated that the soils investigated (a cross-section of soils from Scotland) are more likely to respond to reagents that target iron ions rather than calcium, aluminium or phosphorus ions. Furthermore, the concentration of iron and soil pH did not appear to have an effect on the performance of the enhancement techniques. For the techniques tested, colour enhancement was observed on all light coloured substrates while enhancement on dark coloured fabrics, denim and leatherette was limited due to poor contrast with the background. Of the chemical enhancement reagents tested, 2,2'-dipyridil was a suitable replacement for the more common enhancement technique using potassium thiocyanate. The main advantages are the use of less toxic and flammable solvents and improved clarity and sharpness of the enhanced impression. The surface morphology of the fabrics did not have a significant effect on the enhancement ability of the reagents apart from a slight tendency for diffusion to occur on less porous fabrics such as polyester and nylon/lycra blends. PMID:22153620

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

2012-06-10

189

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

2012-01-01

190

Improvement in the transmission of iodine-polyvinyl alcohol polarizers  

NASA Astrophysics Data System (ADS)

Controlled bleaching of the iodine dichromophore from iodine-polyvinyl alcohol polarizers has been demonstrated to result in a dramatic increase in transmission. Internal transmission of 95 percent for linearly polarized light has been observed in the spectral range of 5000-6000 A. Degradation of polarizer extinction is most severe at shorter wavelengths; however, the transmittance for the crossed polarization remains less than 0.1 percent through much of the visible spectrum.

Gunning, W. J.; Foschaar, J.

1983-10-01

191

Investigation of the alumina properties with adsorbed polyvinyl alcohol  

Microsoft Academic Search

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

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

2011-01-01

192

Kinetics of thermal degradation of poly(vinyl chloride)  

Microsoft Academic Search

Extensively studied thermal degradation of polyvinyl chloride (PVC) occurs with formation of free hydrogen chloride and conjugated\\u000a double bonds absorbing light in visible region. Thermogravimetric monitoring of PVC blends degradation kinetics by the loss\\u000a of HCl is often complicated by evaporation and degradation of plasticizers and additives. Spectroscopic PVC degradation kinetics\\u000a monitoring by absorbance of forming conjugated polyenes is specific

Vadim V. Krongauz; Yann-Per Lee; Anthony Bourassa

193

Effect of inorganic salts on the crystallinity of polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

We use IR spectroscopy to study the crystallinity of polyvinyl alcohol films cast from aqueous solutions containing inorganic salts. We have established that adding salt leads to an increase in the degree of crystallinity of the polymer. The crystallizing effect of the studied salts increases in the series Na2CO3 = Na2SO4 < NH4Cl < CsCl = NaCl < KCl.

Tretinnikov, O. N.; Zagorskaya, S. A.

2012-01-01

194

Hybrid material polyvinyl alcohol-stannic acid/stannic oxide  

NASA Astrophysics Data System (ADS)

Hybrid materials polyvinyl alcohol (PVA)-stannic acid and PVA-SnO2 were produced in the form of transparent films. Their investigations by means of optical spectroscopy, X-ray analysis, thermo-gravimetry, and mass-spectrometry were carried out as well as electrical measurements. The model is discussed where the polymeric chains of inorganic constituent are linked by coordinative bonds with carbon polymeric chains. Photoconductivity of PVA-SnO2 was discovered.

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

2013-07-01

195

Surface acoustic wave humidity sensor using polyvinyl-alcohol film  

Microsoft Academic Search

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

M. Penza; V. I. Anisimkin

1999-01-01

196

Heterogeneous photocatalytic oxidation of polyvinyl alcohol in water  

Microsoft Academic Search

Titanium dioxide mediated photocatalytic degradation of polyvinyl alcohol (PVA) was studied in an annular photoreactor with two 6W (Emax=365nm) UV lamps as light source. In the presence of both TiO2 and light, and initial concentration of 30mg\\/l, 55.3% of PVA was found to degrade after an hour. The effects of initial concentration, pH and the addition of H2O2 on the

Yingxu Chen; Zhenshi Sun; Ye Yang; Qiang Ke

2001-01-01

197

Chromate reduction by Microbacterium liquefaciens immobilised in polyvinyl alcohol  

Microsoft Academic Search

A polyvinyl alcohol-based immobilisation technique has been utilised for entrapping the newly-isolated chromate- reducing bacterium, Microbacterium liquefaciensMP30. Three immobilisation methods were evaluated: PVA- nitrate, PVA-borate and PVA-alginate. Chromate reduction was studied in batch and continuous-flow bioreactors, where the beads maintained integrity during continuous operation. PVA-borate and PVA-alginate cell beads showed a higher rate and extent of chromate reduction than PVA-nitrate

P. Pattanapipitpaisal; N. L. Brown; L. E. Macaskie

2001-01-01

198

Small-angle neutron scattering study of the mesostructure of bioactive coatings for stone materials based on nanodiamond-modified epoxy siloxane sols  

NASA Astrophysics Data System (ADS)

The structure formation of sol-gel-derived epoxy siloxane compositions with different ratios of the main precursors ( R TEOS/EPONEX 1510 = 16/38, 27/27, 38/16 wt %) and with different concentrations of detonation synthesis nanodiamonds ( c DND = 0.05, 0.10, 0.20 wt %) has been investigated using small-angle neutron scattering (SANS). Based on the SANS data, it has been revealed that the synthesized epoxy siloxane xerogels are systems with a two-level fractal structure, in the formation of which the siloxane component plays a dominant role. It has been found that the fractal dimension D m2 and the radius of gyration R g2 of clusters in the epoxy siloxane compositions decrease with an increase in the content of the siloxane component. It has been established that the introduction of small additions of detonation synthesis nanodiamonds (less than 1 wt %) into the epoxy siloxane composition with an equal ratio of the main precursors R TEOS/EPONEX 1510 = 27/27 wt % leads to a transition from the two-level to three-level structure organization and affects the fractal dimension D m and the radius of gyration R g of the formed clusters.

Khamova, T. V.; Shilova, O. A.; Kopitsa, G. P.; Almásy, L.; Rosta, L.

2014-01-01

199

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

SciTech Connect

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

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

2008-01-01

200

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

201

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

202

Sol-gel derived transparent zirconium-phenyl siloxane hybrid for robust high refractive index LED encapsulant.  

PubMed

We report a zirconium-phenyl siloxane hybrid material (ZPH) that can be used as a robust LED encapsulant. The ZPH encapsulant was fabricated via hydrosilylation-curing of sol-gel derived multifunctional (vinyl- and hydride-functions) siloxane resins containing phenyl-groups and Zr-O-Si heterometallic phase for achieving a high refractive index (n ? 1.58). In thermal aging, the ZPH LED encapsulant exhibited superior performances with a high optical transparency (?88% at 450 nm) and exhibited high thermal stability (no yellowing at 180 °C for 1008 h), compared to a commercial LED encapsulant (OE-6630, Dow Corning Corporation). This suggests potential for ZPH to be a robust LED encapsulant. PMID:24564295

Kim, Yong Ho; Bae, Jun-Young; Jin, Jungho; Bae, Byeong-Soo

2014-03-12

203

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.

204

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

PubMed

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

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

2014-02-17

205

Synthesis of novel poly{methyl-[3-(9-indolyl)propyl]siloxane}-based nonlinear optical polymers via postfunctionalization  

Microsoft Academic Search

A novel series of nonlinear optical (NLO) polysiloxanes with a high density of chromophore moieties based on poly{methyl-[3-(9-indolyl)propyl]siloxane} (PMIPS) were synthesized by a post functional strategy. First, PMIPS (P1) was prepared through hydrosilylation reaction, then P1 is partially formylated by the reaction between P1 and the reagents of dimethylformamide (DMF) and phosphorus oxychloride under the standard Vilsmeier reaction conditions, and

Zhen Li; Jianli Hua; Qianqian Li; Cheng Huang; Anjun Qin; Cheng Ye; Jingui Qin

2005-01-01

206

In Vitro and In Vivo Evaluation of the Estrogenic, Androgenic, and Progestagenic Potential of Two Cyclic Siloxanes  

Microsoft Academic Search

The purpose of these experiments was to determine the poten- tial estrogenic, androgenic, and progestagenic activity of two cyclic siloxanes, octamethylcyclotetrasiloxane (D4) and decame- thylcyclopentasiloxane (D5). Receptor-binding experiments and a luciferase reporter gene assay were used to determine if the materials were able to bind and activate either the estrogen receptors (ERs) or progesterone receptors (PRs)—a or b. The rat

Anne L. Quinn; Jane M. Regan; Joseph M. Tobin; Brian J. Marinik; Joan M. McMahon; Debra A. McNett; Christopher M. Sushynski; Steven D. Crofoot; Paul A. Jean; Kathleen P. Plotzke

2007-01-01

207

Preparation of novel carbon microfiber/carbon nanofiber-dispersed polyvinyl alcohol-based nanocomposite material for lithium-ion electrolyte battery separator  

E-print Network

Preparation of novel carbon microfiber/carbon nanofiber-dispersed polyvinyl alcohol December 2012 Keywords: Li-ion battery separator Polyvinyl alcohol Carbon micro-nanofibers Suspension polymerization Ionic conductivity A novel nanocomposite polyvinyl alcohol precursor-based material dispersed

Singh, Jayant K.

208

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

209

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

210

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

211

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

212

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

PubMed Central

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

Deogade, Suryakant C.

2012-01-01

213

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

214

Self-presentation and Impression Formation through Photographs in an LGBT Online Dating Community.  

E-print Network

?? This netnographic and autoethnographic study examines self-presentation and impression formation through photographs presented on a gay online dating community, Qruiser. The theoretical framework of… (more)

Shum, Kai Fat

2014-01-01

215

The effect of disinfecting alginate and addition cured silicone rubber impression materials on the physical properties of impressions and resultant casts.  

PubMed

Four commercially available disinfectants were tested and the dimensional stability and detail reproduction of impressions and their resultant casts were measured according to ANSI/ISO specifications. Results showed that alginate impressions immersed in chlorhexidine exhibited considerable dimensional change if not poured immediately. Moreover, alginate impressions soaked in a paraldehyde agent (Virkon) for more than 2 minutes produced casts of inferior surface quality whilst those sprayed and left in contact with phenol derivatives (C&J Spray) for 30 minutes resulted in casts which demonstrated statistically and clinically significant dimensional changes. Addition cured silicone impressions exhibited minimal dimensional change regardless of the disinfection regime employed and the resultant casts were accurate with acceptable surface quality. PMID:10218014

al-Omari, W M; Jones, J C; Wood, D J

1998-09-01

216

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

217

Features of IR Holograms recorded on Polyvinyl alcohol films  

SciTech Connect

When holograms are recorded with continuous-wave radiation from a CO/sub 2/ laser in Plexiglas, a diffraction efficiency of about 20% may be attained. Results are presented on pulsed IR holograms recorded on films of polyvinyl alcohol. The holograms are recorded with a TEA CO/sub 2/ laser giving a pulse length of 3 musec. The diffraction-efficiency results are given for holographic gratings having a spatial frequency of 50 mm/sup -1/. The IR recording mechanism related to relief change is evidently characteristic of other polymeric recording media.

Durasov, V.M.; Chatei, A.V.; Rubanov, A.S.; Stashkevich, I.V.

1986-01-01

218

Starch-polyvinyl alcohol cast film-performance and biodegradation  

SciTech Connect

Starch-polyvinyl alcohol (PVOH) cast films were prepared in the absence of plasticizer. Their physical and biodegradable properties were examined. Moisture absorption by the films was similar to that of PVOH at low humidity and increased linearly as the relative humidity increased. The tensile strength of the films decreased with increased humidity and did not display significant improvement with increased PVOH content. Higher PVOH content improved elongation when the relative humidity was 80% or higher. Biodegradation studies revealed that the presence of PVOH in the films slowed the rate of degradation.

Chen, Liang; Imam, S.H.; Stein, T.M. [National Center for Agricultural Utilization Research, Peoria, IL (United States)] [and others

1996-10-01

219

Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol  

SciTech Connect

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

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

2008-01-01

220

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

221

Sodium deoxycholate functionalized graphene and its composites with polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

Sodium deoxycholate (SDC), a kind of bile derivative, is used to noncovalently functionalize graphene. Stable and high concentration (up to 20 mg ml-1) of graphene colloid is obtained. The stabilization mechanism is revealed to be hydrophobic interaction, electrostatic repulsion and hydrogen bonding. Single-layer and few-layer graphene are obtained in the colloid. Subsequently, the obtained graphene sheets are incorporated into a polyvinyl alcohol (PVA) matrix by solution casting to fabricate PVA/graphene composites. Morphological observations substantiate the homogeneous dispersion of graphene in the PVA matrix and strong interfacial adhesion between them. Significant improvements in tensile strength and modulus of the composite films are observed.

Wang, Lanwei; Liao, Ruijuan; Tang, Zhenghai; Lei, Yanda; Guo, Baochun

2011-11-01

222

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

E-print Network

Rapidly dissolving poly(vinyl alcohol)/cyclodextrin electrospun nanofibrous membranes Joshua L complexes of poly(vinyl alcohol) (PVA), hydroxypropyl-b-cyclodextrin (HPbCD), and a poorly water soluble a synergistic role in facilitating fiber formation, enabling us to produce fibers with a high cyclodextrin (e

Khan, Saad A.

223

Histologic Long-term Follow-up after Embolization with Polyvinyl Alcohol Particles  

Microsoft Academic Search

Summary: A large facial vascular malformation was embolized with polyvinyl alcohol particles twice in 8 years. Resected tissue enabled long-term examination of this material, confirming its chemical inertness and revealing minimal tissue reaction to it apart from calcification. No particle migration, fragmentation, or absorption occurred. There was some recanalization of occluded vessels. Most vessels containing polyvinyl alcohol particles, and all

George S. Davidson; Karel G. Terbrugge

224

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

225

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

226

Nonfunctionalized polydimethyl siloxane superhydrophobic surfaces based on hydrophobic-hydrophilic interactions.  

PubMed

Superhydrophobic surfaces based on polydimethyl siloxane (PDMS) were fabricated using a 50:50 PDMS-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°. The active surface layer for the superhydrophobicity was approximately 100 ?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. PMID:21294505

Polizos, Georgios; Tuncer, Enis; Qiu, Xiaofeng; Aytu?, Tolga; Kidder, Michelle K; Messman, Jamie M; Sauers, Isidor

2011-03-15

227

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

228

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

229

Poly (dimethyl siloxane) micro/nanostructure replication using proton beam written masters  

NASA Astrophysics Data System (ADS)

Proton beam writing (PBW) has been proven to be a powerful tool for fabricating micro and nanostructures with high aspect ratio. However, being a direct-write technique, and therefore, a serial process, PBW is not economic for low cost multiple component production. Techniques for replicating PBW structures with low cost are necessary for applications in for example nanofluidics, tissue engineering and optical devices. We have investigated casting poly (dimethyl siloxane) (PDMS Sylgard 184, Dow Corning Corp.) with PBW structures as masters. First, a 2 MeV focused H2+ beam was written into a 2 ?m thick PMMA layer spin coated onto 50 ?m thick Kapton film substrate. Next, these PMMA structures, with details down to 700 nm, were replicated with PDMS. Without any release coating treatment, PDMS circular pillars, 700 nm in diameter were successfully replicated. We also fabricated a nickel master with nanofeature dimensions and 2 ?m depth using proton beam writing and sulfamate electroplating. The nickel master was used to successfully replicate a prototype DNA separation chip using PDMS.

Shao, P. G.; van Kan, J. A.; Ansari, K.; Bettiol, A. A.; Watt, F.

2007-07-01

230

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

231

Nanocomposites of ZnS and poly-(dimethyl)-block-(phenyl)siloxane as a new high-refractive-index polymer media  

NASA Astrophysics Data System (ADS)

In the present paper, we describe a new and original method to obtain transparent, siloxane-based composites, with high refractive index (up to 1.68). The method is based on the decomposition of Zn-siloxane, mixed with a poly-(dimethyl)-block-(phenyl)siloxane matrix in different ratios. It was found that after treatment of such mixed metal-containing polymer blend with H2S, the nanoparticles of ZnS are formed, with the size in a 1- to 5-nm range, which allow effective increase of the refractive index of the nanocomposite mixture with poly-(dimethyl)-block-(phenyl)siloxane without loss of film transparency. We succeded to increase the refractive index from 1.54 (pure matrix) up to 1.68 (composite with a ZnS content of 4.6 vol.%). The siloxane-based compositions are optically transparent, which makes it possible to use them as light-emitting diodes or solar cell sealants or adhesives.

Sergienko, Natalia; Godovsky, Dmitri; Zavin, Boris; Lee, Minjong; Ko, Minjin

2012-03-01

232

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

Microsoft Academic Search

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

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

2010-01-01

233

Effect of water in amorphous polyvinyl formal: insights from molecular dynamics simulation.  

PubMed

In this study, molecular dynamics simulations were performed to study the influence of water on polyvinyl formal. The effects of adding different concentrations of water (0, 0.23, 0.47, 0.94, 1.40, 1.86, 2.76, 3.65 and 4.52 wt%) to a copolymer of polyvinyl acetal, polyvinyl alcohol, and polyvinyl acetate were investigated. Simulated results clearly indicated that the radius of gyration of the polymer chain decreased whereas the cohesive energy density increased with the addition of water molecules. The diffusion coefficient initially decreased and then monotonically increased with increasing water concentration, and the same trend was observed for the fractional free volume. The results provide insights into the molecular structural and physical properties of polyvinyl formal with different water contents. PMID:25605599

Yin, Qiang; Zhang, Lin; Jiang, Bo; Yin, Qinjian; Du, Kai

2015-01-01

234

Impression Creep Characteristics of a Cast Mg Alloy  

NASA Astrophysics Data System (ADS)

The creep behavior of the cast Mg-6Al-0.3Mn alloy (AM60) was investigated by impression testing under constant punching stress in the range 150 to 650 MPa and at temperatures in the range 423 to 523 K, corresponding to 0.458 < T/T m < 0.567. The creep behavior can be divided into two stress regimes, with a change from the low-stress regime to the high-stress regime occurring, depending on the testing temperature, around 0.021 < ( ?/ G) < 0.033. Based on the steady-state power-law creep relationship, the stress exponents of 4 to 6 and 8 to 12 were obtained at low and high stresses, respectively. When the experimental creep rates were normalized to the pipe diffusion coefficient, however, the stress exponents of about 5 and 10 were obtained for the low- and high-stress regimes, respectively. The low-stress regime activation energies of about 76 to 84 kJ mol-1, which are close to 80 kJ mol-1 for dislocation-pipe diffusion in the Mg, and stress exponents in the range 4 to 6 suggest that the operative creep mechanism is dislocation climb. This behavior is in contrast to the high-stress regime, in which the stress exponents of 8 to 12 and activation energies of about 134 to 165 kJ mol-1 are indicative of a power-law breakdown.

Kondori, B.; Mahmudi, R.

2009-08-01

235

How shadows shape our impression of rough surfaces  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

236

Hydrolytic Stability Of Polyvinyl Alcohol (PVA) Iodine Polarizers  

NASA Astrophysics Data System (ADS)

This paper presents a study of the hydrolytic stability of high contrast polyvinyl alcohol-iodine type polarizers. The central topic is the relationship between visible light transmission, polarization efficiency and their effect on hydrolytic stability. The format includes a series of graphs, illustrating first the dependence of polarization efficiency on visible light transmission. The spectral distribution of transmitted light before and after hydrolytic stability conditioning is also discussed. Of particular interest is the transmission dependence of hydrolytic stability. This is first presented as the rate of degradation in polarization efficiency as a function of conditioning time for selected transmissions. This data is then presented in a more condensed form. These graphs will illustrate the time required for polarization efficiency degradation to 90% of initial efficiency as a function of visible light transmission and temperature. A new generation of American Hoechst Corporation Film Division polarizers exhibit improved hydrolytic stability. Their performance will be compared with other polyvinyl alcohol-iodine liquid crystal display polarizers.

Bolt, Larry

1982-05-01

237

Study of Thermodynamical Properties of Polyvinyl Acetate in Tetrahydrofuran  

NASA Astrophysics Data System (ADS)

The propagation of ultrasonic waves and the measurement of their velocity in solutions form an important tool for the evaluation of various acoustical and thermodynamical parameters which give an insight into the nature of miscibility and molecular interactions in polymer solutions. In the present study, the ultrasonic velocity, density, viscosity measurements have been made in 0.1 M solution using pulse echo overlap technique at 293 K at the different concentrations of polyvinyl acetate in tetrahydrofuran. Thermo-acoustical parameters viz., adiabatic compressibility, molar sound velocity, molar compressibility, expansion coefficient, acoustic impedance, van der Waals' constant and internal pressure have been computed from the experimental data. The nature of polymer/solvent interaction and the effect of concentration on the molecular interaction are studied. The nonlinear variations of polyvinyl acetate in tetrahydrofuran have been studied. The variation of ultrasonic velocity and other thermo-acoustical parameters shows nonlinear increase or decrease with molar concentration which suggest semi-compatibility of the polymer in the given solvent.

Tabhane, Priyanka V.; Chimankar, Omprakash P.; Tabhane, Vilas A.

2012-10-01

238

Cross-linked polyvinyl alcohol and method of making same  

SciTech Connect

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

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

1981-06-09

239

The effects of expectancy violations on early attention to race in an impression-formation paradigm  

Microsoft Academic Search

Previous research has demonstrated that early attentional components of the event-related potential (ERP) reflect differential attention to race during person perception. There is also evidence that inconsistency between stereotypic information following impression formation leads to greater neural processing in later ERP components. However, research has not examined how expectancy violations following impression formation affect the early attentional processing of race.

Cheryl Dickter; Ivo Gyurovski

2011-01-01

240

The effects of expectancy violations on early attention to race in an impression-formation paradigm  

Microsoft Academic Search

Previous research has demonstrated that early attentional components of the event-related potential (ERP) reflect differential attention to race during person perception. There is also evidence that inconsistency between stereotypic information following impression formation leads to greater neural processing in later ERP components. However, research has not examined how expectancy violations following impression formation affect the early attentional processing of race.

Cheryl Dickter; Ivo Gyurovski

2012-01-01

241

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

242

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

PubMed

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

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

2014-01-01

243

Ultraviolet Light Stable and Transparent Sol-Gel Methyl Siloxane Hybrid Material for UV Light-Emitting Diode (UV LED) Encapsulant.  

PubMed

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

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

2015-01-21

244

The First Impression of Data Sent by Two Martian Rovers  

NASA Astrophysics Data System (ADS)

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

Kochemasov, G. G.

245

Tat peptide-decorated gelatin-siloxane nanoparticles for delivery of CGRP transgene in treatment of cerebral vasospasm  

PubMed Central

Background Gene transfer using a nanoparticle vector is a promising new approach for the safe delivery of therapeutic genes in human disease. The Tat peptide-decorated gelatin-siloxane (Tat-GS) nanoparticle has been demonstrated to be biocompatible as a vector, and to have enhanced gene transfection efficiency compared with the commercial reagent. This study investigated whether intracisternal administration of Tat-GS nanoparticles carrying the calcitonin gene-related peptide (CGRP) gene can attenuate cerebral vasospasm and improve neurological outcomes in a rat model of subarachnoid hemorrhage. Method A series of gelatin-siloxane nanoparticles with controlled size and surface charge was synthesized by a two-step sol-gel process, and then modified with the Tat peptide. The efficiency of Tat-GS nanoparticle-mediated gene transfer of pLXSN-CGRP was investigated in vitro using brain capillary endothelial cells and in vivo using a double-hemorrhage rat model. For in vivo analysis, we delivered Tat-GS nanoparticles encapsulating pLXSN-CGRP intracisternally using a double-hemorrhage rat model. Results In vitro, Tat-GS nanoparticles encapsulating pLXSN-CGRP showed 1.71 times higher sustained CGRP expression in endothelial cells than gelatin-siloxane nanoparticles encapsulating pLXSN-CGRP, and 6.92 times higher CGRP expression than naked pLXSN-CGRP. However, there were no significant differences in pLXSN-CGRP entrapment efficiency and cellular uptake between the Tat-GS nanoparticles and gelatin-siloxane nanoparticles. On day 7 of the in vivo experiment, the data indicated better neurological outcomes and reduced vasospasm in the subarachnoid hemorrhage group that received Tat-GS nanoparticles encapsulating pLXSN-CGRP than in the group receiving Tat-GS nanoparticles encapsulating pLXSN alone because of enhanced vasodilatory CGRP expression in cerebrospinal fluid. Conclusion Overexpression of CGRP attenuated vasospasm and improved neurological outcomes in an experimental rat model of subarachnoid hemorrhage. Tat-GS nanoparticle-mediated CGRP gene delivery could be an innovative strategy for treatment of cerebral vasospasm after subarachnoid hemorrhage. PMID:23576867

Tian, Xin-Hua; Wang, Zhi-Gang; Meng, Han; Wang, Yu-Hua; Feng, Wei; Wei, Feng; Huang, Zhi-Chun; Lin, Xiao-Ning; Ren, Lei

2013-01-01

246

Metabolites of hexamethyldisiloxane and decamethylcyclopentasiloxane in Fischer 344 rat urine--a comparison of a linear and a cyclic siloxane.  

PubMed

Hexamethyldisiloxane (MM or HMDS) and decamethylcylclopentasiloxane (D(5)) are examples of a linear and a cyclic siloxane, respectively. These volatile low molecular weight siloxanes are of significant commercial importance. To aid in the pharmacokinetic investigations, major metabolites of MM and D(5) were identified in urine collected from Fischer (F-344) rats administered [(14)C]MM and [(14)C]D(5) orally and via intravenous injection. The metabolite profiles were obtained using a high-pressure liquid chromatography (HPLC) system equipped with a radioisotope detector. The metabolite elution was carried out on a C(18) column using an acetonitrile/water mobile phase. The structural assignments were based on GC-MS analysis of the tetrahydrofuran extract of urine containing the metabolites. Some of the metabolites in the extracts were first protected with trimethylsilyl groups prior to GC-MS analysis using bis(trimethylsiloxy)trifluoroacetamide or highly purified hexamethyldisiloxane. The structures were also confirmed by comparisons with synthetic (14)C-labeled metabolite standards. The following are among the major metabolites identified in the case of MM: Me(2)Si(OH)(2), HOMe(2)SiCH(2)OH, HOCH(2)Me(2)SiOSiMe(2)CH(2)OH, HOMe(2)SiOSiMe(2)CH(2)-OH, HOCH(2)Me(2)SiOSiMe(3), and Me(3)SiOH. The metabolites of D(5) are as follows: Me(2)Si(OH)(2), MeSi(OH)(3), MeSi(OH)(2)OSi(OH)(3), MeSi(OH)(2)OSi(OH)(2)Me, MeSi(OH)(2)OSi(OH)Me(2), Me(2)Si(OH)OSi(OH)Me(2), Me(2)Si(OH)OSiMe(2)OSi(OH)Me(2), nonamethylcyclopentasiloxanol, and hydroxymethylnonamethylcyclopentasiloxane. No parent MM or D(5) was present in urine The presence of certain metabolites such as HOMe(2)SiCH(2)OH and Me(2)Si(OH)(2) in MM and D(5), respectively, clearly established the occurrence of demethylation at the silicon-methyl bonds. Metabolites of the linear siloxane are structurally different from that obtained for cyclic siloxane except for the commonly present Me(2)Si(OH)(2). Mechanistic pathways for the formation of the metabolites were proposed. PMID:12527702

Varaprath, Sudarsanan; McMahon, Joan M; Plotzke, Kathleen P

2003-02-01

247

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

PubMed Central

Background and aims The most common method for alginate impression disinfection is spraying it with disinfecting agents, but some studies have shown that these impressions can be immersed, too. The aim of this study was to evaluate the dimensional stability of alginate impressions following disinfecting by spray and immersion methods. Materials and methods Four common disinfecting agents (Sodium Hypochlorite, Micro 10, Glutaraldehyde and De-conex) were selected and the impressions (n=108) were divided into four groups (n=24) and eight subgroups (n=12) for disinfecting by any of the four above-mentioned agents by spray or immersion methods. The control group (n=12) was not disinfected. Then the impressions were poured by type III Dental Stone Plaster in a standard method. The results were ana-lyzed by descriptive methods (mean and standard deviation), t-test, two-way analysis of variance (ANOVA) and Duncan test, using SPSS 14.0 software for windows. Results The mean changes of length and height were significant between the various groups and disinfecting methods. Regarding the length, the greatest and the least amounts were related to Deconex and Micro 10 in the immersion method, respectively. Regarding height, the greatest and the least amounts were related to Glutaraldehyde and Deconex in the im-mersion method, respectively. Conclusion Disinfecting alginate impressions by Sodium Hypochlorite, Deconex and Glutaraldehyde by immersion method is not recommended and it is better to disinfect alginate impressions by spraying of Micro 10, Sodium Hypochlorite, Glutaraldehyde and immersion in Micro 10. PMID:23346340

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

2010-01-01

248

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

249

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

250

Structural insights into enzymatic degradation of oxidized polyvinyl alcohol.  

PubMed

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

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

2014-09-01

251

Surface Sulfonation of Polyvinyl Chloride by Plasma for Antithrombogenicity  

NASA Astrophysics Data System (ADS)

To enhance the blood compatibility of Polyvinyl Chloride (PVC) film, the film was modified by SO2/O2 gas plasma treatment. The effect of surface sulfonation of PVC treated by various SO2/O2 gas plasma depended on the volume ratio O2/(SO2 + O2). When the volume ratio was 0.5, the effect of sulfonation was the best. Sulfonic acid groups were specifically and efficiently introduced onto the PVC surface, which was proved by x-ray photoelectron spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transfer Infrared (ATR-FTIR) spectroscopy. The surface microstructure of modified PVC film was studied with scanning electron microscopy (SEM). The antithrombogenicity of the samples was determined by the activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) and plasma recalcification time (PRT) tests and platelet adhesion experiment. The results indicated that the antithrombogenicity of modified PVC was improved remarkably.

Liu, Peng; Chen, Yashao

2004-06-01

252

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

253

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

254

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

255

Estimation of mechanochemical dechlorination rate of poly(vinyl chlorde).  

PubMed

Poly(vinyl chloride) (PVC) was ground in air with CaO in the presence of quartz powder as a grinding aid by a small-scale planetary ball mill to investigate the relation of the dechlorination rate of PVC with the impact energy of the balls calculated from a computer simulation based on the Discrete Element Method under various conditions. Mechanochemical dechlorination proceeds as the grinding progresses and is improved with an increase in both the mill speed and the amount of balls introduced into the mill. The same trend can be seen in the relation between the specific normal impact energy of the balls and the rotational speed. The relationship between the observed dechlorination rate and the computed normal impact energy of the balls is linear, with a correlation coefficient of 0.965. This relationship can be used to estimate the dechlorination rate of PVC in a large-scale planetary ball mill. PMID:11944691

Mio, Hiroshi; Saeki, Shu; Kano, Junya; Saito, Fumio

2002-03-15

256

[Test method for 6 phthalates in polyvinyl chloride].  

PubMed

A test method for 6 phthalates, bis(2-ethylhexyl)phthalate, dibutyl phthalate, benzyl butyl phthalate, diisononyl phthalate, diisodecyl phthalate and di-n-octyl phthalate, in polyvinyl chloride (PVC) was developed. GC/MS was used in the SIM mode for the separation and detection of phthalates. For preparation of the test solution, the extraction method with acetone-hexane mixture (3 : 7) and the dissolution method with tetrahydrofuran and ethanol were compared and it was confirmed that each method gave good recoveries. Dilution of the test solution was effective to reduce the influence of PVC. In a collaborative study with nine laboratories, the intra-laboratory variations showed good repeatability, but the measurements at some laboratories deviated widely. It appears that this method is unsuitable for the judgment of acceptability, but it may be suitable for the determination of phthalate content in PVC products. PMID:22200751

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

2011-01-01

257

Behaviour of polymer (poly(vinyl chloride)) membrane systems  

NASA Astrophysics Data System (ADS)

Radiotracer studies are discussed for alkaline earth metal ion-permeation through poly(vinyl chloride) matrix membranes containing sensors based on organophosphates and on the tetraphenylborates of the complex of barium with a polyethoxylate. There is selective permeation of calcium ions, from among alkaline earth cations, through the phosphate-based membranes, but the polyethoxylate membranes do not permeate ions to any significant extent. The phosphate-based membranes maintain stable current flows over prolonged periods under conditions of applied potential and are not affected by polarity reversals. For example, current flows of 5 - 6 ?A are maintained for 2 V applied potential. Current flows fall rapidly for the polyethoxylate membranes and do not recover on repeated polarity reversal of the applied potential. The possibility of the permeation of metal ions of the first transition series through the phosphate-based membranes is discussed briefly.

Moody, G. J.; Thomas, J. D. R.

258

Structural changes in chlorine implanted poly(vinyl alcohol) films  

NASA Astrophysics Data System (ADS)

Poly(vinyl alcohol) (PVA) films were implanted with chlorine ions in the fluence range of 10 13-10 16 ions/cm 2 on to PVA films of thickness 40 ?m. FTIR spectroscopic study was carried out to see the structural changes. It was found that oxidation and carbonization progressively occurs in the film as a function of total fluence. The structural change occurs in the form of scission of C-C, C-OH and C-H bonds. SEM studies were carried out which revealed the surface defects in the form of cracks and etching. ESCA studies established that Cl + ions get deposited on the surface. Changes in the crystallinity were observed from the X-ray diffraction studies. The implanted chlorine ions enhanced the electrical conductivity by the order of 10 +2 S/cm.

Bhat, N. V.; Nate, M. M.; Kurup, M. B.; Bambole, V. A.

2007-08-01

259

Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets  

SciTech Connect

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 ..mu..m) on the target (outside diameter approx.350--850 ..mu..m). Thicker coatings are obtained by repeated applications of the coating solution. 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.

1985-05-01

260

Silver Nanoparticle Fabrication by Laser Ablation in Polyvinyl Alcohol Solutions  

NASA Astrophysics Data System (ADS)

A laser ablation technique is applied for synthesis of silver nanoparticles in different concentrations of polyvinyl alcohol (PVA) aqueous solution. The ablation of high pure silver plate in the solution is carried out by a nanosecond Q-switched Nd:YAG pulsed laser. X-ray diffraction and transmission electron microscopy are implemented to explore the particles sizes. The effects of PVA concentrations on the absorbance of the silver nanoparticles are studied as well, by using a UV-vis spectrophotometer. The preparation process is carried out for deionized water as a reference sample. The comparison of the obtained results with the reference sample shows that the formation efficiency of nanoparticles in PVA is much higher and the sizes of particles are also smaller.

Halimah Mohamed., K.; Mahmoud Goodarz, Naseri; Amir, Reza Sadrolhosseini; Arash, Dehzangi; Ahmad, Kamalianfar; Elias, B. Saion; Reza, Zamiri; Hossein Abastabar, Ahangar; Burhanuddin, Y. Majlis

2014-07-01

261

Cross-linked polyvinyl alcohol films as alkaline battery separators  

SciTech Connect

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

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

1983-02-01

262

Biodegradable thermoplastic composites based on polyvinyl alcohol and algae.  

PubMed

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

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

2008-03-01

263

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

264

Growth characteristics of selected fungi on polyvinyl film  

SciTech Connect

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

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

1986-04-01

265

Growth characteristics of selected fungi on polyvinyl chloride film.  

PubMed

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

1986-04-01

266

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

267

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

268

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

269

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

270

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

ERIC Educational Resources Information Center

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

Amorose, Anthony J.; Hollembeak, Jill

2005-01-01

271

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

PubMed

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

Frampton, Mark B; Zelisko, Paul M

2014-05-10

272

Effect of two different disinfectants on dimensional stability of newer alginate impression materials over five days.  

PubMed

The effect of two different disinfectants on the dimensional stability of two alginate impression materials over five days was investigated. 60 impressions were made under standardised conditions, 30 with each alginate, of which ten were disinfected in each disinfectant and ten were controls. Impressions were stored over a period of five days in a container with 100% humidity. Measurements were made between four points. Two-way analysis of variance indicated no differences in the change from baseline to day 5 between any of the combinations of alginate and disinfectant. Only two of the changes between baseline and day 5 reached statistical significance at the p < 0.01 level. Therefore it can be concluded that within the limitations of this study when newer alginate impression materials are disinfected they remain stable over 5 days. PMID:22645797

Ambrose, Prem Kumar; Juszczyk, Andrzej S; Clark, Robert K F; Radford, David R

2011-12-01

273

Chapter 5 Development of Adiabatic Force Field for Polyvinyl Chloride PVC  

E-print Network

CPVC 5.1 Introduction Chlorinated polyvinyl chloride has become an important specialty polymer due the understanding of CPVC, we developed the adiabatic quantum force eld that accurately described the rotational

Goddard III, William A.

274

Spectroscopic investigation of the thermal conversion of catalytically dehydrated polyvinyl alcohol  

SciTech Connect

The authors examine the structural conversion of dehydrated polyvinyl alcohol thermally treated at temperatures exceeding the temperature of the catalytic dehydration. The authors used electron and infrared spectroscopy to study the thermal conversion of catalytically dehydrated polyvinyl alcohol in an inert atmosphere and in air. Aluminum chloride and hydrogen chloride were used as catalysts of the dehydration. Spectra are shown which were obtained in the visible part from ALCL/sub 3/-containing polyvinyl alcohol films after their thermal treatment in an inert gas flow. It is shown that optimal temperatures must be selected to obtain high-quality recordings of optical information when the dehydration of polyvinyl alcohol is to be used to advantage.

Gavrilov, M.Z.

1986-09-01

275

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

(1) The chemical substance identified as siloxanes and silicones, de-Me, 3-[4-[[[3-(dimethylamino) propyl]amino] carbonyl]-2-oxo-1-pyrrolidinyl]propyl Me (PMN P-97-332) is subject to reporting under this section for the significant new uses described in paragraph (a)(2) of this...

2010-07-01

276

Crouching Theropods in Taxonomic Jungles: Ichnological and Ichnotaxonomic Investigations of Footprints with Metatarsal and Ischial Impressions  

Microsoft Academic Search

Tracks and traces of crouching theropods are rare, known from only three specimens from the Lower Jurassic of New England and the Lower to ?mid Jurassic of China. The New England specimens reveal manus, metatarsal and sub-crescentic ischial callosity impressions associated with Grallator-like tracks. The Chinese traces reveal metatarsal traces and a sub-triangular ischial callosity impression associated with Eubrontes-like tracks.

Martin Lockley; Masaki Matsukawa; Li Jianjun

2003-01-01

277

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

Microsoft Academic Search

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

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

2001-01-01

278

Diagnostic impression cytology: a simple technique for the diagnosis of external eye disease.  

PubMed

The technique of impression cytology was used for cytologic examination of conjunctival samples from 128 patients with a variety of external eye diseases. The method of sample collection and the staining procedure are described. Microscopic examination showed 62 cases with allergic conjunctivitis, 23 with bacterial or viral infection, 26 cases with changes typical of dry eye and 17 cases with non-specific chronic inflammation. The cytologic features and numerous applications of impression cytology are discussed. PMID:9439889

Divani, S N; Margari, C; Zikos, G A; Zikos, A; Papavassiliou, G B

1997-12-01

279

Organically crosslinked polyvinyl alcohol copolymetric gels for use under harsh reservoir conditions  

SciTech Connect

This patent describes a process for recovering oil from a subterranean oil-bearing formation having relatively high permeability zones and relatively low permeability zones penetrated by at least one production well in fluid communication with a substantial portion of the formation. It comprises: injecting into the formation an aqueous gel-forming composition comprising water, a water-dispersible polyvinyl alcohol copolymer, the polyvinyl alcohol copolymer selected from the group consisting of copolymers of vinyl alcohol and vinyl alkyl sulfonate either.

Haskin, D.H.; Shu, P.

1990-07-10

280

The Effect of Disinfection by Spray Atomization on Dimensional Accuracy of Condensation Silicone Impressions  

PubMed Central

Background and aims The condensation silicone impression materials are available, but there is little knowledge of their accuracy after disinfection. The objective of this study was to evaluate the effect of the disinfection by spray atomization on dimensional accuracy of condensation silicone impressions. Materials and methods Impressions were made on a stainless steel master model containing a simulated two complete crown preparation with an edentulous space interposed using Spidex® and Rapid® impression materials. 44 impressions were made with each material, of which 16 were disinfected with 5.25% sodium hypochlorite, 16 were disinfected with 10% iodophor and 12 were not disinfected. Three dimensional measurements of working casts, including interpreparation distance, height, and diameter, were calculated using a measuring microscope graduated at 0.001 mm. Dimensional changes (mm) between the disinfected and non-disinfected working casts were compared. One-way analysis of variance (ANOVA) was employed to analyze the data (?=0.05). Results Disinfection of each condensation silicone material by spraying atomization with two different disinfectant material resulted in significant change in interpreparation distance (p<0.05). Changes in height and diameter were only significant in Spidex® impressions (p<0.05). Conclusion Significant changes in the mean dimensions were seen as a result of disinfection by spraying; however, the dimensional changes do not seem great enough to cause critical positional distortion of teeth when fixed partial denture restorations are made. PMID:23346339

Saleh Saber, Fariba; Abolfazli, Nader; Kohsoltani, Maryam

2010-01-01

281

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

282

Effect of rinsing hydrocolloid impressions using acidic electrolyzed water on surface roughness and surface hardness of stone models.  

PubMed

The present study investigated the effect on the surface quality of resultant stone models of rinsing hydrocolloid impressions using acidic electrolyzed water. Two brands of alginate impression materials (Aroma Fine DFIII, Jeltrate Plus), an agar impression material (Ajisai) designed for agar/alginate combined impression, and dental stone (New Plastone) were used to make the test specimens. For the rinsing of impressions, acidic electrolyzed water having a pH value of 2.3, an oxidation-reduction potential of 1,230 mV, and a residual chlorine concentration of 45.0 ppm, was prepared. Alginate, agar and agar/alginate combined impressions were rinsed using acidic electrolyzed water or tap water for 30 sec and 3 min, and as a control, these impressions were not rinsed with any water. Disk-shaped stone specimens obtained from rinsed impressions were evaluated with respect to surface roughness (Ra) and surface hardness (scratch depth), and scanning electron microscope (SEM) observations were performed. The stone specimens obtained from rinsed impressions using acidic electrolyzed water showed a surface quality equivalent to that of the stone specimens obtained from the rinsed impression using tap water. This result suggests that the use of acidic electrolyzed water for rinsing is an acceptable treatment for hydrocolloid impressions, so long as the rinsing time is from 30 sec to 3 min. PMID:12613503

Nakagawa, Hisami; Hiraguchi, Hisako; Uchida, Hirobumi; Tanabe, Naoki

2002-12-01

283

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

284

Polyvinyl alcohol functionalized cobalt ferrite nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

285

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

PubMed

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

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

2014-05-14

286

Gas production in the radiolysis of poly(vinyl chloride).  

PubMed

The yields of H2 and Cl- were determined in the radiolysis of deaerated, aerated, and water mixtures of poly(vinyl chloride) (PVC) powders with gamma-rays and 5 MeV He ions. H2 yields with gamma-rays are low at about 0.25 molecule/100 eV and they double with He ion radiolysis indicating a second order formation process. The production of H2 in the gamma-radiolysis of water-PVC mixtures is much greater than expected from the weight fraction of the components and is due to acidification of the aqueous phase by the evolution of HCl from the polymer. Cl- yields in the gamma-radiolysis of PVC with number average weights of 22,000, 47,000, and 99,000 Daltons are 19.6, 33.8, and 32.5 atoms/100 eV. Cl- continuously evolves from the polymer for days following radiolysis. The extremely large yields suggest that a chain process involving radicals stabilized on the polymeric chain are responsible. Reflectance UV/vis and infrared spectroscopy show subtle changes in the PVC with radiolysis while UV/vis absorption spectra clearly indicate the formation of polyenes with 1 to 11 units. Cl- formation is probably initiated by Cl radical production followed by an electron rearrangement mechanism along the PVC chain to produce more Cl- and polyenes. PMID:18335913

LaVerne, Jay A; Carrasco-Flores, Eduardo A; Araos, M S; Pimblott, Simon M

2008-04-17

287

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

PubMed

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

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

2013-02-01

288

The development and characterization of degradable poly(vinyl ester) and poly(vinyl ester)/PEO block copolymers  

NASA Astrophysics Data System (ADS)

The development of biodegradable materials is a challenging and important problem in polymer science. A review of the state of the art in degradable materials is presented, which reveals that current biodegradable materials do not exhibit the thermal or mechanical properties necessary for widespread applications. One strategy for toughening polymeric materials, which has previously been applied to non-degradable thermoplastics and thermoplastic elastomers, is the formation of block copolymers. Poly(vinyl esters) (PVE) homopolymers are known to have a wide range of properties, but PVE block copolymers comprise a class of inexpensive and (bio)degradable materials that were previously unknown. Therefore, the synthesis and properties of these block copolymers were explored in an effort to develop robust degradable materials. This thesis research probes the reaction conditions necessary for the reversible-addition fragmentation chain transfer (RAFT) polymerization and chain extension reactions of vinyl ester monomers. PVE di- and triblock copolymers are synthesized and studied, and the triblock copolymers display extremely poor toughness due to their relatively low molecular weights in light of the high entanglement molecular weight of the poly(vinyl acetate) center block. Attempts to improve the mechanical properties of these materials focus on the incorporation of poly(ethylene oxide) (PEO) as a low entanglement molecular weight and biocompatible center block in PVE-containing triblock copolymers. Depending on the choice of PVE endblocks and the overall polymer composition, crystallization of the PEO block can be controlled, confined, or inhibited. Polymers in which PEO crystallization is completely inhibited exhibit enhanced mechanical properties and behave as weak thermoplastics. In order to understand the relationship between the inhibition of PEO crystallization and the mechanical properties of PVE/PEO materials, these polymers were studied using dynamic mechanical spectroscopy, wide angle X-ray scattering, small angle X-ray scattering, differential scanning calorimetry, and uniaxial tensile tests. By combining insights gained from these techniques, a complex picture emerges that explains the enhanced mechanical properties of these materials based on the type and location of thermal transitions, amorphous PEO entanglements, and the strain-induced crystallization of PEO. This work represents an important step toward developing robust materials with tunable properties containing (bio)degradable components.

Lipscomb, Corinne Elizabeth

289

Biocompatibility and reduced drug absorption of sol-gel-treated poly(dimethyl siloxane) for microfluidic cell culture applications.  

PubMed

Poly(dimethyl siloxane) (PDMS)-based microfluidic devices are now commonly used for a wide variety of biological experiments, including cell culture assays. However, the porous, hydrophobic polymer matrix of PDMS rapidly absorbs small hydrophobic molecules, including hormones and most small-molecule drugs. This makes it challenging to perform experiments that require such substances in PDMS microfluidic devices. This study presents evidence that a sol-gel treatment of PDMS that fills the polymer matrix with silica nanoparticles is effective at reducing the absorption of drugs into the material while preserving its biocompatibility, transparency, and oxygen permeability. We show that the absorption of two anticancer drugs, camptothecin and a kinase inhibitor, is reduced to such an extent that on-chip microfluidic cell culture experiments can recapitulate the results obtained off-chip. PMID:20936785

Gomez-Sjoberg, Rafael; Leyrat, Anne A; Houseman, Benjamin T; Shokat, Kevan; Quake, Stephen R

2010-11-01

290

Surface morphology studies of multiblock and starblock copolymers of poly(a-methyl styrene) and poly (dimethyl siloxane)  

SciTech Connect

Surface morphology and compositions of multiblock and starblock copolymers of poly(a-methyl styrene) (PMS) and poly(dimethyl siloxane) (PDMS) were investigated by cross-sectional transmission electron microscopy, angle- and energy-dependent ESCA, and infrared spectroscopy. The extent of surface segregation of PDMS was determined for multiblock and starblock copolymers to depth of 210{angstrom}. No surface excess was with high PDMS bulk concentrations (60 wt%) have a highly oriented lamellar morphology in the near air surface region, and the topmost air surface region (27 {angstrom}) is exclusively composed of PDMS. The PMS-PDMS block copolymers with lower PDMS bulk concentrations (40 wt%) have lesser or no domain orientation and the surface region includes detectable PMS.

Chen, X.; Gardella, J.A. Jr. [State Univ. of New York, Buffalo, NY (United States); Kumler, P.L. [State Univ. of New York College, Fredonia, NY (United States)

1993-12-31

291

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

PubMed

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

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

2014-01-21

292

Investigation of optical loss changes in siloxane polymer waveguides during thermal curing and aging  

NASA Astrophysics Data System (ADS)

In high performance electronic systems, with increasing chip speed and larger number of processors, the system performance is being limited by off-chip metal interconnects. In such systems, optical interconnects are being considered to replace electrical interconnects because of their high capacity for bandwidth and due to having less constraints on link length. Polymer waveguides are attractive as an optical interconnect medium because they can enable low-cost and high-density interconnects, and can be relatively easily integrated into organic board-level processes. The optical loss in the polymer optical waveguides is the key criterion used to evaluate their performance. Although thermal curing and aging factors can change the optical loss of polymer waveguides significantly, there is limited study on the effect of those factors. Also the field-use conditions of an embedded optoelectronic package with these polymer waveguides have not been reported in existing literature. In this research, the relationship between optical loss variations in polymer waveguides with polymer properties during thermal curing is investigated. The evolution of degree-of-cure is determined from differential scanning calorimetry and compared to optical absorption from spectroscopy. Optical loss due to scattering mechanisms is related to local density fluctuations, which is studied using dielectric analysis. Optical loss measurements are conducted on both uncladded and cladded waveguides during isothermal cure, which result in certain optical loss trends. Based on the trends, the underlying mechanisms for the optical loss variations are proposed and a cure process schedule to realize the lowest optical loss is recommended. Process-induced thermal stresses can also affect the polymer waveguide by introducing stress birefringence. In this work, the stress-optical coefficients of the siloxane polymer are extracted and employed in a numerical modeling method to determine the stress-induced birefringence in an optical waveguide system. The outlined methodology is generic in nature and can be applied to different waveguide geometries, planarization materials, and substrate/board materials to assess how stress-induced birefringence can be minimized for a given polymer core material. This research also seeks to understand the effect of thermal aging in polymer waveguides, and develop an optical loss model to ensure that the optical performance over extended field-use conditions is within the optical loss budget. The thermal-aging dependent optical loss is determined for waveguide samples at several different accelerated temperature conditions. To determine the field-use conditions, the temperature distribution in the vicinity of the embedded laser and the polymer waveguide is determined. Using such thermal experimental data, the analytical reliability models were employed to determine the optical loss with time, and provide a practical way of determining whether the optical waveguides would perform within the optical loss budget during field-use conditions.

Hegde, Shashikant G.

293

Quantitative and high mass ToF-SIMS studies of siloxane segregation in hydrogel polymers using cryogenic sample handling techniques  

NASA Astrophysics Data System (ADS)

This paper examines the capabilities of cryogenic sample handling to examine composition and structure of hydrogel materials where siloxane components are central to the analysis. XPS analysis of multicomponent polymers with cryogenic sample handling following exposure to aqueous environments has revealed the composition and kinetics of near surface reorganization for siloxane and fluorocarbon containing polymers. In this study we report results from a ToF-SIMS protocol for cryogenic sample handling applied to the analysis of surface changes upon hydration/dehydration of hydrogel polymers. Comparison of results from angle dependent XPS and ToF-SIMS are discussed for a range of commercial soft contact lens materials. Both methods detected changes in surface chemistry between the hydrated (frozen) and dehydrated surfaces. Analysis of the hydrated surfaces detected polymer components indicative of the commercial formulation as well as ice clusters. Analysis of the dehydrated materials detected changes in surface chemistry relative to the hydrated surface in addition to loss of water due to sample dehydration. A quantitative standard additions method for ToF-SIMS data was used to determine submonolayer amounts of PDMS impurities at the surface of the hydrogels. ToF-SIMS analysis of a series of seven poly (allyl methacrylate- g-dimethylsiloxane), AMA- g-DMS, graft copolymers in the hydrated state revealed high mass oligomeric ion distributions for systems with bulk PDMS content greater than 25 wt.%. This marks the first time that detection of high mass oligomeric ion distributions from hydrated (frozen) surfaces has been reported. Analysis of the dehydrated surface detected formation of high mass oligomeric ion distributions for systems with PDMS bulk content greater than 15 wt.%, but only detected these ion distributions in wet (frozen) samples when the bulk concentration was greater than 25 wt.%.

Hook, Daniel J.; Valint, Paul L.; Chen, Lu; Gardella, Joseph A.

2006-07-01

294

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

PubMed

Nitric oxide (NO) is an important mediator in cardiovascular system to regulate vascular tone and maintain tissue homeostasis. Its role in vascular cell regulation makes it promising to address the post-surgery restenosis problem. However, the application of NO is constrained by its high reactivity. Here, we developed a novel NO-releasing gelatin-siloxane nanoparticle (GS-NO NP) to deliver NO effectively for vascular cell regulation. Results showed that gelatin-siloxane nanoparticles (GS NPs) could be synthesized via sol-gel chemistry with a diameter of ?200 nm. It could be modified into GS-NO NPs via S-nitrosothiol (RSNO) modification. The synthesized GS-NO NPs could release a total of ?0.12 µmol/mg NO sustainably for 7 days following a first-order exponential profile. They showed not only excellent cytocompatibility, but also rapid intracellularization within 2 h. GS-NO NPs showed inhibition of human aortic smooth muscle cell (AoSMC) proliferation and promotion of human umbilical vein endothelial cell (HUVEC) proliferation in a dose-dependent manner, which is an important approach to prevent restenosis. With GS-NO NP dose at 100 µg/mL, the proliferation of AoSMCs could be slowed down whereas the growth of HUVECs was significantly promoted. We concluded that GS-NO NPs could have potential to be used as a promising nano-system to deliver NO for vascular cell regulation. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 929-938, 2015. PMID:24853642

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

2015-03-01

295

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

PubMed Central

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

296

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

297

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

PubMed

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

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

2015-02-01

298

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

299

Predicting performance expectations from affective impressions: Linking affect control theory and status characteristics theory.  

PubMed

Affect control theory (ACT) and status characteristics theory (SCT) offer separate and distinct explanations for how individuals interpret and process status- and power-relevant information about interaction partners. Existing research within affect control theory offers evidence that status and power are related to the affective impressions that individuals form of others along the dimensions of evaluation and potency, respectively. Alternately, status characteristics theory suggests that status and power influence interaction through the mediating cognitive construct of performance expectations. Although both theories have amassed an impressive amount of empirical support, research has yet to articulate theoretical and empirical connections between affective impressions and performance expectations. The purpose of our study is to address this gap. Elaborating a link between ACT and SCT in terms of their central concepts can serve as a stepping stone to improving the explanatory capacity of both theories, while providing a potential bridge by which they can be employed jointly. PMID:25592917

Dippong, Joseph; Kalkhoff, Will

2015-03-01

300

The Effects of Disinfectants on Dimensional Accuracy and Surface Quality of Impression Materials and Gypsum Casts  

PubMed Central

Background The study aimed to evaluating the effect of disinfecting impression materials on the dimensional accuracy and surface quality of the resulting casts. Methods Impressions of a steel die constructed according to ANSI/ADA specification No.18 were made with each of alginate, addition cured silicone, condensation cured silicone and zinc oxide eugenol paste, and disinfected consequently by each of 0.2% chlorhexidine gluconate, 1% sodium hypochlorite, 2% gluteraldehyde for 5 minutes, and 0.5% sodium hypochlorite for 10 minutes. Dimensions of the disinfected impressions and their resultant casts were measured using a computerized digital caliper, and the dimensional changes were calculated. Reproduction of detail and surface quality of the resultant casts were assessed by grading casts surfaces according to a specific scoring system. Results The 0.5% sodium hypochlorite was found to produce the least dimensional changes in all the impression materials. Corsodyl produced the maximum changes in both alginate and zinc-oxide eugenol while addition-cured silicon was most affected by Gluteraldehyde and condensation-cured silicon was most affected by Hexana. The dimensional changes, however, were minimal and clinically insignificant. Addition-cured silicon showed the best surface quality and dimensional stability followed by condensation-cured silicon. Alginate and zinc-oxide eugenol had poorer surface quality and were affected to a higher extent by the disinfection procedures. Conclusions The results were comparable with the standard specifications for dimensional stability. Recommendations were made for the use of 10 minutes immersion in 0.5% sodium hypochlorite as the most appropriate disinfection protocol to the investigated impression materials. Keywords Disinfectants; Gypsum casts; Impressions; Alginate; Addition-cured silicone; Sodium hypochlorite PMID:22505972

Amin, Wala M.; Al-Ali, Muna H.; Al Tarawneh, Sandra K.; Taha, Sahar Th.; Saleh, Mohamed W.; Ereifij, Nadia

2009-01-01

301

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

302

In-situ investigation of polyvinyl formal irradiated with GeV Au ions  

NASA Astrophysics Data System (ADS)

Polyvinyl formal (Formvar®) foils were irradiated with 5.4 MeV/u Au ions and analysed in-situ by residual gas analysis and infrared spectroscopy. The experiment was performed at the new materials-research beamline (M-branch) at the universal linear accelerator of the GSI Helmholtz Centre in Darmstadt (Germany). Simultaneously analysing outgassing fragments and changes within the irradiated polymer film allows monitoring details of the degradation process. Ion-induced degradation of polyvinyl formal is characterized by fragmentation of side chains of the polymer backbone. The infrared spectra show the formation of unsaturated hydrocarbons and ketones. A possible degradation mechanism is proposed including the production of enols as reported earlier for degradation of polyvinyl alcohol exposed to gamma radiation.

Seidl, T.; Baake, O.; Hossain, U. H.; Bender, M.; Severin, D.; Trautmann, C.; Ensinger, W.

2012-02-01

303

Forming first impressions of others in schizophrenia: impairments in fast processing and in use of spatial frequency information.  

PubMed

Individuals form first impressions of others all the time, which affects their social functioning. Typical adults form threat impressions in faces with neutral expressions quickly, requiring less than 40 ms. These impressions appear to be mediated by low spatial frequency (LSF) content in the images. Little is known, however, about mechanisms of first impression formation in schizophrenia. The current study investigated how quickly individuals with schizophrenia can form consistent impressions of threat compared with controls and explored the mechanisms involved. Patients and controls were presented intact, LSF- or high spatial frequency (HSF)-filtered faces with durations that varied from 39 to 1703 ms and were asked to rate how threatening each face was on a scale from 1 to 5. In order to assess the speed of impression formation for intact faces, correlations were calculated for ratings made at each duration compared to a reference duration of 1703 ms for each group. Controls demonstrated a significant relation for intact faces presented for 39 ms, whereas patients required 390 ms to demonstrate a significant relation with the reference duration. For controls, LSFs primarily contributed to the formation of consistent threat impressions at 39 ms, whereas patients showed a trend for utilizing both LSF and HSF information to form consistent threat impressions at 390 ms. Results indicate that individuals with schizophrenia require a greater integration time to form a stable "first impression" of threat, which may be related to the need to utilize compensatory mechanisms such as HSF, as well as LSF, information. PMID:25458862

Vakhrusheva, J; Zemon, V; Bar, M; Weiskopf, N G; Tremeau, F; Petkova, E; Su, Z; Abeles, I Y; Butler, P D

2014-12-01

304

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.

305

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

306

Structural and electronic properties of poly(vinyl alcohol) using density functional theory  

SciTech Connect

The first principles calculations have been carried out to investigate the structural, electronic band structure density of states along with the projected density of states for poly(vinyl alcohol). Our structural calculation suggests that the poly(vinyl alcohol) exhibits monoclinic structure. The calculated structural lattice parameters are in excellent agreement with available experimental values. The band structure calculations reveal that the direct and indirect band gaps are 5.55 eV and 5.363 eV respectively in accordance with experimental values.

Dabhi, Shweta, E-mail: shwetadabhi1190@gmail.com; Jha, Prafulla K., E-mail: shwetadabhi1190@gmail.com [Department of Physics, Maharaja Krishnakumasinhji Bhavnagar University, Bhavnagar-364001 (India)

2014-04-24

307

Preparation and swelling behavior of physically crosslinked hydrogels composed of poly(vinyl alcohol) and chitosan  

Microsoft Academic Search

The physically crosslinked poly(vinyl alcohol)\\/chitosan (CS) composite hydrogels were prepared by cyclic freezing\\/thawing\\u000a techniques, and the microstructure and swelling behavior of the hydrogels in the simulated gastric (pH 1.0) and intestinal\\u000a (pH 7.4) media were investigated. The experimental results of infrared spectra (IR), scanning electron microscope (SEM) and\\u000a differential scanning calorimetry (DSC) demonstrated that poly(vinyl alcohol) and chitosan had good

Guanghua He; Hua Zheng; Fuliang Xiong

2008-01-01

308

Structural and electronic properties of poly(vinyl alcohol) using density functional theory  

NASA Astrophysics Data System (ADS)

The first principles calculations have been carried out to investigate the structural, electronic band structure density of states along with the projected density of states for poly(vinyl alcohol). Our structural calculation suggests that the poly(vinyl alcohol) exhibits monoclinic structure. The calculated structural lattice parameters are in excellent agreement with available experimental values. The band structure calculations reveal that the direct and indirect band gaps are 5.55 eV and 5.363 eV respectively in accordance with experimental values.

Dabhi, Shweta; Jha, Prafulla K.

2014-04-01

309

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

310

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

311

Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel cells with different solution conductivities  

E-print Network

Spray-on polyvinyl alcohol separators and impact on power production in air-cathode microbial fuel, PA 16802, USA h i g h l i g h t s Polyvinyl alcohol (PVA) separators were prepared with spray Polyvinyl alcohol a b s t r a c t Separators are used to protect cathodes from biofouling and to avoid

312

Quality of written prescriptions and master impressions for fixed and removable prosthodontics: a comparative study  

Microsoft Academic Search

Aim: Various ethical and legal guidelines require dental practitioners to adequately design, prescribe and fabricate good quality prostheses. The purpose of this investigation was to examine the quality of written instructions and choice of impression trays and materials for both fixed and removable prosthodontics in Ireland and the United Kingdom.Materials and methods: A pre-piloted questionnaire was distributed to a number

P F Allen; D Lynch

2005-01-01

313

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

314

An impressive amount of work has been done to date on improving the electrical efficiency of  

E-print Network

Abstract An impressive amount of work has been done to date on improving the electrical efficiency of these technologies offer far greater gains in efficiency than can be gotten via electrical optimizations (e.g. power, with increased power supply and fan efficiencies. However, storage presents other significant opportunities

Paris-Sud XI, Université de

315

OfficeMax ImPress is your printing services resource.  

E-print Network

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

Miami, University of

316

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.

317

Evaluation of the Clinical Global Impression Scale among individuals with social anxiety disorder  

Microsoft Academic Search

Background. The clinical Global Impression Scale (CGI) is commonly used as a primary outcome measure in studies evaluating the efficacy of treatments for anxiety disorders. The current study evaluated the psychometric properties and predictors of clinicians' ratings on an adapted version of the CGI among individuals with social anxiety disorders. Method. An independent assessor administered the CGI Severity of Illness

T. I. ZAIDER; R. G. HEIMBERG; D. M. FRESCO; F. R. SCHNEIER; M. R. LIEBOWITZ

2003-01-01

318

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

319

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

320

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

321

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

E-print Network

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

322

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

ERIC Educational Resources Information Center

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

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

2007-01-01

323

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

Microsoft Academic Search

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

Johanna Lass-Hennemann; Linn K. Kuehl; André Schulz; Melly S. Oitzl; Hartmut Schachinger; André Aleman

2011-01-01

324

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

E-print Network

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

Chen, Yiling

325

An Examination of Pace's Model of Student Development and College Impress  

Microsoft Academic Search

Pace (1979b) delineates a model for the study of student development and college impress. That model was the basis for his development of the College Student Experiences Questionnaire (CSEQ) and the Community College Student Experiences Questionnaire (CCSEQ). His perspective is similar to Astin (19701984) and Tinto (19751986) in that each posit student time and effort to be the key constructs

Corinna A. Ethington; Robert A. Horn

2007-01-01

326

An experimental exploration of the relationship between subjective impressions of illumination and physical fidelity  

Microsoft Academic Search

Two experiments were carried out to explore the effect of rendering and interface fidelity on subjective impressions of illumination and perceived presence after exposure to a virtual environment (VE). In particular, a study that compares a real-world task situation to its computer graphics simulation counterpart is presented. The computer graphics simulation was based on photometry data acquired in the real-world

Katerina Mania; Andrew Robinson

327

An Examination of Pace's Model of Student Development and College Impress  

ERIC Educational Resources Information Center

Pace (1979b) delineates a model for the study of student development and college impress. That model was the basis for his development of the College Student Experiences Questionnaire (CSEQ) and the Community College Student Experiences Questionnaire (CCSEQ). His perspective is similar to Astin (1970, 1984) and Tinto (1975, 1986) in that each…

Ethington, Corinna A.; Horn, Robert A.

2007-01-01

328

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

329

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

PubMed

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

Todorov, Alexander; Porter, Jenny M

2014-05-27

330

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

E-print Network

1 The International Space Station (ISS) is an impressive home away from home with a structure the International Space Station. In addition, I will give an update on Commercial Crew Development and NASA's plan training. Currently, Dr. Auñón serves in the International Space Station Operations Branch to handle

Maranas, Costas

331

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

332

Towards a Pedagogy of Listening: Impressions of the Centre for Early Childhood Education, Loyalist College, Belleville, Ontario.  

ERIC Educational Resources Information Center

Highlights impressions of the Centre for Early Childhood Education, the Centre's recent work to interpret the philosophy of the Reggio Emilia approach, and examples of how the centre has transformed its practice within a Canadian context. Relates impressions of their environment, traces several examples in the development of the environment, and…

Wien, Carol Anne

1998-01-01

333

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

334

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

Microsoft Academic Search

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

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

2004-01-01

335

Near-Infrared Laser Absorption of Poly(vinyl chloride) at Elevated Temperatures  

E-print Network

Near-Infrared Laser Absorption of Poly(vinyl chloride) at Elevated Temperatures James D. Van de Ven, unpigmented state are highly transmissive of light in the near-infrared range, thus allowing laser of light detection [2, 3]. Within the near-infrared region nat- ural polymers have nearly no absorption [2

Van de Ven, James D.

336

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

Microsoft Academic Search

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

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

337

Magnetic Resonance Imaging Analysis of Molecular Mobility during Dissolution of Poly(vinyl alcohol) in Water  

E-print Network

for recycling,4 the semiconductor industry,5 and packaging.6 The dissolution of a polymer in a solvent involves) in Water B. Narasimhan,*, J. E. M. Snaar, R. W. Bowtell, S. Morgan,§ C. D. Melia,§ and N. A. Peppas microstructure and molecular motion during dissolution of poly(vinyl alcohol) (PVA) in water. One

Peppas, Nicholas A.

338

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

339

Far-infrared spectroscopy of a nanocomposite of polyvinyl alcohol and lead sulfide nanoparticles  

Microsoft Academic Search

A nanocomposite consisting of lead sulfide (PbS) nanoparticles (NPs) with average diameter of 26 ?, according to absorption threshold shift, and polyvinyl alcohol (PVA) was characterized using far-infrared absorption spectroscopy. The experimental results are consistent with theoretical calculations that include proper mechanical boundary conditions at the nanocrystal-host interface.

R. Kostic; M. Romcevic; D. Markovic; J. Kuljanin; M. I. Comor

2006-01-01

340

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

Microsoft Academic Search

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

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

1999-01-01

341

Metronidazole loaded carboxymethyl tamarind kernel polysaccharide-polyvinyl alcohol cryogels: Preparation and characterization.  

PubMed

The purpose of present study was to prepare composite hydrogels of carboxymethyl tamarind kernel polysaccharide and polyvinyl alcohol employing freeze thaw-treatment and evaluate them for release behavior. The effect of concentrations of carboxymethyl tamarind kernel polysaccharide, polyvinyl alcohol, and freeze-thaw cycles on the % release of metronidazole was studied employing central composite experimental design. The result of the study revealed that the concentration of carboxymethyl tamarind kernel polysaccharide and interaction effect of concentrations of carboxymethyl tamarind kernel polysaccharide and polyvinyl alcohol influenced the release of metronidazole significantly. The optimal calculated parameters were concentration of carboxymethyl tamarind kernel polysaccharide-6.0% (w/v), concentration of polyvinyl alcohol-8.53% (w/v) and freeze-thaw cycles-4, which provided cryogels with a release of 75.77% over a period of 6h. The formation of cryogels was confirmed by Fourier-transformed infrared spectroscopy and X-ray diffraction studies. Thermal studies revealed higher thermal stability of cryogel. PMID:25301698

Meenakshi; Ahuja, Munish

2015-01-01

342

Miscibility Studies of Polyesteramides of Linseed Oil and Dehydrated Castor Oil with Poly(vinyl alcohol)  

Microsoft Academic Search

Blends of two polymers have been widely investigated to enhance or modify some of their physical or mechanical characteristics for specific applications. The investigation of miscibility of a pair of polymers is a necessary step in the investigation of the properties of the blends. Poly(vinyl alcohol)(PVA) is a commercial polymer that yields tough films of high tensile strength. They are,

H. O. Sharma; Manawwer Alam; Uffana Riaz; Sharif Ahmad; S. M. Ashraf

2007-01-01

343

Ionic reactions in pulse irradiated poly(vinyl chloride) film—the effect of plasticizers  

Microsoft Academic Search

Poly(vinyl chloride), PVC+plasticizer (DEHP, TOTM) films were pulse irradiated using electron accelerator and the transient species generated in these matrices were analysed. The absorption spectra of plasticizers ions (anion and cation type) were identified in PVC system using as a model 2-propanol and sec-butyl chloride solutions of respective plasticizers. The mechanism of reactions is proposed and discussed.

J. Mayer; M. Szadkowska-Nicze

2006-01-01

344

KINETIC ASPECTS OF AGING OF POLY(VINYL CHLORIDE)BASED POLYMER MATERIALS  

Microsoft Academic Search

The results of the complex study of samples of plasticized poly(vinyl chloride) (PVC) subjected to aging under model and climatic conditions or being in use for a long time (from 15 to 30 years at 253–301 K) studied by various techniques and the mechanism of their aging are presented in the article. Using the thermogravimetric, chromatographic, ultraviolet and infrared spectroscopic

G. E. ZAIKOV; K. Z. GUMARGALIEVA; T. V. POKHOLOK; Y. U. V. MOISEEV; V. G. ZAIKOV

2000-01-01

345

Use of Polymeric Plasticizers in Polyvinyl Chloride to Reduce Conventional Plasticizer Migration for Critical Applications  

Microsoft Academic Search

Di-(2-ethyl hexyl) phthalate (DEHP), a conventional plasticizer in polyvinyl chloride (PVC), was partially replaced by polymeric plasticizers. Three different elastomers such as nitrile rubber (NBR), carboxylated nitrile rubber (XNBR) and epoxidized natural rubber (ENR) were used as polymeric plasticizers. Mechanical properties and leaching of DEHP of the modified PVC in comparison to the compound containing DEHP alone were investigated. The

M. C. Sunny; P. Ramesh; K. E. George

2004-01-01

346

Thermal degradation of poly(vinyl chloride) plastisols based on low-migration polymeric plasticizers  

Microsoft Academic Search

The analysis of the thermal degradation of poly(vinyl chloride) (PVC) plastisols formulated with low-toxicity polymeric plasticizers is reported. Dynamic and isothermal thermogravimetric analyses are applied to study the behavior of these materials at high temperatures and to evaluate their degradation kinetics. The results used for the optimization of the processing conditions, in particular the cure time and temperature, to maximize

A Jiménez; L Torre; J. M Kenny

2001-01-01

347

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

Microsoft Academic Search

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

A. Sari; K. Kaygusuz

2007-01-01

348

Solid As A Rock: The Utilization of Polyvinyl Acetate to Stabilize and Consolidate Museum Sandstone Objects  

E-print Network

Solid As A Rock: The Utilization of Polyvinyl Acetate to Stabilize and Consolidate Museum Sandstone) commonly used sandstone in creating various objects. Sandstone slabs used in hearth construction these objects unstable. Sandstone is a porous rock. The heat treatment and weathering drives off water and makes

Rock, Chris

349

Nitrate removal by Thiobacillus denitrificans immobilized on poly(vinyl alcohol) carriers  

Microsoft Academic Search

Nitrate contamination is becoming a widespread environmental problem, and autotrophic denitrification with Thiobacillus denitrificans is a promising process considering efficiency, cost and maintenance. The denitrification efficiencies of T. denitrificans were compared in batch reactors between free cells and cells immobilized on polyvinyl alcohol (PVA) carriers made with thrice freezing\\/thawing and boric acid methods. The results indicated that the free cell

Zhenya Zhang; Zhongfang Lei; Xiaoyan He; Zhiyin Zhang; Yingnan Yang; Norio Sugiura

2009-01-01

350

Antimicrobial Effect of An Essential Oil Blend on Surface-attached Salmonella on Polyvinyl Chloride  

Technology Transfer Automated Retrieval System (TEKTRAN)

The majority of drinking water lines for broilers are made of polyvinyl chloride (PVC) and surface attachment of Salmonella on the inner surface of water lines can be the initial stage of biofilm development. These biofilms can be the source of Salmonella infection in water lines and are known to re...

351

POLYVINYL ALCOHOL FIBER REINFORCED ENGINEERED CEMENTITIOUS COMPOSITES: MATERIAL DESIGN AND PERFORMANCES  

Microsoft Academic Search

Polyvinyl alcohol (PVA) fiber is considered as one of the most suitable polymeric fibers to be used as the reinforcement of engineered cementitious composites (ECC), though the unique microstructure characteristics of PVA fiber add challenge to the material design. In this paper, the micromechanics based design procedure for a PVA-ECC suitable for structural applications is described, and practical design considerations

Shuxin Wang; Victor C. Li

352

Tensile and thermal properties of nanocellulose-reinforced poly(vinyl alcohol) nanocomposites  

Microsoft Academic Search

This work reports on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) nanocomposites reinforced with nanocelluloses isolated by the sulfuric acid hydrolysis using commercial microcrystalline cellulose (MCC). Nanocellulose-reinforced PVA nanocomposite films were prepared by the casting method with different nanocellulose loadings, which were exposed to tensile test, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The nanocellulose obtained by

Mi-Jung Cho; Byung-Dae Park

2011-01-01

353

Li ion conducting gel polymer electrolytes based on Poly(vinyl acetate)  

NASA Astrophysics Data System (ADS)

A novel gel polymer electrolyte based on poly(vinyl acetate) and poly(vinylidene fluoride) with different plasticizers was prepared and studied by X-ray diffraction and Ac impedance methods. The blend polymer electrolyte containing propylene carbonate (PC) exhibits the highest conductivity 0.922 × 10-2 Scm-1 at room temperature and the results were discussed.

Rajendran, S.; Mathew, Chithra M.; Marimuthu, T.; Kesavan, K.

2013-06-01

354

Electrospun nanofibers of poly(vinyl alcohol)reinforced with cellulose nanofibrils  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this work, nanofibers of poly(vinyl alcohol) (PVA) reinforced with cellulose nanofibrils (CnF) were produced by electrospinning. The effects of applied voltage, polymer concentration and injection rate, tip-to-collector distance (TCD), rotation speed of the collector, and relative humidity on mor...

355

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

356

Micromechanics-Based Durability Study of Polyvinyl Alcohol-Engineered Cementitious Composite  

Microsoft Academic Search

The durability of engineered cementitious composites (ECC) reinforced with polyvinyl alcohol (PVA) fiber is investigated in this paper. ECCs have been realized as ductile strain-hardening cementitious composites with tensile strain capacity up to 5%. This material is being applied in new construction and for the repair and retrofit of structures. A micromechanics-based approach is adopted in the present durability study.

Victor C. Li; Tetsuo Horikoshi; Atsuhisa Ogawa; Shinichi Torigoe; Tadashi Saito

357

Composite Nafion\\/polyvinyl alcohol membranes for the direct methanol fuel cell  

Microsoft Academic Search

The methanol crossover in the direct methanol fuel cell (DMFC) can be reduced by casting a thin film containing the mixture of polyvinyl alcohol (PVA) and Nafion on a commercial perfluorosulfonic membrane (Nafion, Dupont). In addition to the cell polarization testing, a design factor defined as the reciprocal of the multiplication of the methanol permeation current density and membrane area

Zhi-Gang Shao; Xin Wang; I.-Ming Hsing

2002-01-01

358

The use of a new grade of polyvinyl alcohol for stabilising tissue sections during histochemical incubations  

Microsoft Academic Search

1.The use of a new grade of polyvinyl alcohol (PVA) is described for maintaining tissue integrity during histochemical incubations. The new material has several advantages over the PVA currently used. It is somewhat less viscous and easier to prepare, and it has no reducing effect upon tetrazolium salts.2.No losses of nitrogenous material, or of the “soluble” enzyme 6 phosphogluconate dehydrogenase,

F. P. Altman; Terence Kennedy

1971-01-01

359

Blended chitosan and polyvinyl alcohol membranes for the pervaporation dehydration of isopropanol  

Microsoft Academic Search

Homogeneous membranes were prepared by casting the solution of blended chitosan and polyvinyl alcohol (PVA) on a glass plate. The percent weight of chitosan in the membrane was varied from 0 to 100%. The membrane thickness was in the range of 15–30?m. The membranes were heat treated at 150°C for an hour. After that the membranes were crosslinked by glutaraldehyde

A. Svang-Ariyaskul; R. Y. M. Huang; P. L. Douglas; R. Pal; X. Feng; P. Chen; L. Liu

2006-01-01

360

Embolization of Cerebral Arteriovenous Malformations Achieved with Polyvinyl Alcohol Particles: Angiographic Reappearance and Complications  

Microsoft Academic Search

BACKGROUND AND PURPOSE: The appropriate choice of embolic materials with respect to the permanency of obliterated nidi after embolization and complications related to the pro- cedure is essential for safe and effective embolization of cerebral arteriovenous malformations (AVMs). Our purpose was to ascertain the recanalization and complication rates after AVM treatment with polyvinyl alcohol (PVA) particles. METHODS: Between 1988 and

Takatoshi Sorimachi; Tetsuo Koike; Shigekazu Takeuchi; Takashi Minakawa; Hiroshi Abe; Keiichi Nishimaki; Yasushi Ito; Ryuichi Tanaka

361

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

362

Embolization of intracranial arteriovenous malformations and fistulas with polyvinyl alcohol particles and platinum fibre coils  

Microsoft Academic Search

In order to reduce the recanalization rate of arteriovenous malformations and multiple dural arteriovenous fistulas, embolization was carried out with polyvinyl alcohol (PVA) particles combined with platinum fibre coils in 20 patients. The malformation was occluded more effectively than by PVA alone. Distal deposition of the emboli was obtained by improved steerable catheters (Tracker-18-unibody) and guidewires. The complication rate was

P. H. Nakstad; S. J. Bakke; J. K. Hald

1992-01-01

363

Preliminary study of polyvinyl alcohol-hydrogel (PVA-H) artificial meniscus  

Microsoft Academic Search

Nowadays the importance of knee meniscal function is recognized. The treatment for meniscus injury has been changing from resection to repair. However, depending on the type of injury, meniscectomy cannot be avoided. In consideration of the prognosis in such patients, we developed artificial meniscus using polyvinyl alcohol-hydrogel (PVA-H) with a high water content and performed an animal experiment as preliminary

Masanori Kobayashi; Jyunya Toguchida; Masanori Oka

2003-01-01

364

Testing of polyvinyl alcohol and starch mixtures as biodegradable polymeric materials  

Microsoft Academic Search

The mechanical properties, thermal behaviour and biodegradation of some polymeric materials based on polyvinyl alcohol and starch, in the presence of urea (used as a micro-organism nitrogen source\\/plasticizer) and glycerine (used as a plasticizer) have been studied. The chemical composition optimization of the analysed blends was carried out using a second order factorial experimental design. The progress of biodegradation was

N Tudorachi; C. N Cascaval; M Rusu; M Pruteanu

2000-01-01

365

Linear Dichroism of Cyanine Dyes in Stretched Polyvinyl Alcohol Films: A Physical Chemistry Laboratory Experiment.  

ERIC Educational Resources Information Center

Provides background information, procedures, and results of an undergraduate physical chemistry experiment on the polarization of absorption spectra of cyanine dyes in stretched polyvinyl alcohol films. The experiment gives a simple demonstration of the concept of linear dichromism and the validity of the TEM method used in the analyses. (JN)

Natarajan, L. V.; And Others

1983-01-01

366

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

367

Lasting Impressions  

ERIC Educational Resources Information Center

In this article, the author discusses how the matter of civil rights, and in particular the treatment of black people at the hands of white people, was conveyed to him most powerfully by three men of Harvard. The first was his high school headmaster, Herbert W. Smith, who introduced their class to the horrors of apartheid through the writings of…

Cottle, Thomas J.

2004-01-01

368

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

369

Impressive progress.  

PubMed

Asia's population accounts for about 60% of world population, and it will grow from 3.1 billion in 1990 to 3.7 billion in 2000. Europe's population of 490 million is not expected to change significantly by 2000. The average total fertility rate (TFR) in Asia in 1991 is estimated to be 3.3. Yemen has the highest TFR (7.4). In 2010 the Asian population will number 4.19 billion, and in 2925 it will further increase to 4.97 billion. Family planning (FP) in Indonesia, Thailand, Japan, China, and in the newly industrialized economies of Hong Kong, Singapore, Taiwan, and Korea have been successful. The fertility rate has dropped to 3.0 in Indonesia and 2.2 in Thailand. The rate of growth has also diminished in India from 2.22% during 1971-82 to 2.11% during 1981-91. The Philippines has adopted the maternal child health (MCH) approach to promote FP. The Integrated Family Planning Project in China has generated a community-based FP/MCH movement by increasing the confidence of the populace especially in rural areas. The UN agencies, bilateral agencies, and international non-governmental organizations based in developed countries have provided family planning assistance in Asia. The National Family Planning Coordinating Board (BKKBN) of Indonesia is sharing its family planning experience with Bangladesh, Nigeria, and Tanzania. BKKBN also signed a memorandum of understanding on cooperation in FP with its Vietnamese counterpart in April 1992. Such technical cooperation will be more effective if UN agencies and donors from developed countries provide financial support. PMID:12343886

Taniguchi, H

1992-08-01

370

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

NASA Astrophysics Data System (ADS)

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

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

2010-03-01

371

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

372

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

373

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

374

First impressions count: a controlled investigation of social skill following closed head injury.  

PubMed

This study examined social skills in 14 closed head injured (CHI) patients who were assessed at four months post-injury and compared with 19 orthopaedic control (OC) patients. Social skills deficits were found to be more common in the CHI patients, of whom over half were classified as socially unskilled. CHI patients displayed poorer social skills in the earlier (but not later) part of an extended social interaction, indicating that they make a poor first impression. It is suggested that poor initial impression formation skills may be one reason why CHI patients fail to establish and maintain friendships. Implications of these findings for patient management are discussed. Close others of CHI patients reported higher levels of mood disturbance. Higher levels of close other hostility were associated with social skills deficits in CHI patients. PMID:8251961

Spence, S E; Godfrey, H P; Knight, R G; Bishara, S N

1993-09-01

375

Complete denture secondary impression technique to minimize distortion of ridge and border tissues.  

PubMed

A technique has been described with which a physiologic and anatomic registration of the attached and unattached tissue of the denture-bearing areas can be attained. Clear acrylic resin trays aid in eliminating excessive displacement at the secondary impression phase. Inadequacies of the mucostatic concept include: Failure to register the tissues, which are important for retention and stability Certain metal bases that are part of this procedure can be implemented by only a small number of technicians Increased cost There are two shortcomings of the tissue-loading technique for complete denture impressions. Resulting retention and stability lasts only for a short period of time. Unwanted ridge resorption and tissue changes occur. PMID:3903136

Klein, I E; Broner, A S

1985-11-01

376

Lateral OFC Activity Predicts Decision Bias due to First Impressions during Ultimatum Games  

Microsoft Academic Search

Despite the prevalence and potentially harmful consequences of first impression bias during social decision-making, its precise neural underpinnings remain unclear. Here, on the basis of the fMRI study using ultimatum games, the authors show that the responders' decisions to accept or reject offers were significantly affected by facial trustworthiness of proposers. Analysis using a model-based fMRI method revealed that activity

Hackjin Kim; Min-Jo Choi; In-Ji Jang

2011-01-01

377

Lateral OFC Activity Predicts Decision Bias due to First Impressions during Ultimatum Games  

Microsoft Academic Search

Despite the prevalence and potentially harmful consequences of first impression bias during social decision-making, its precise neural underpinnings remain unclear. Here, on the basis of the fMRI study using ultimatum games, the authors show that the responders' decisions to accept or reject offers were significantly affected by facial trustworthiness of proposers. Analysis using a model-based fMRI method revealed that activity

Hackjin Kim; Min-Jo Choi; In-Ji Jang

2012-01-01

378

Accuracy of 3D white light scanning of abutment teeth impressions: evaluation of trueness and precision  

PubMed Central

PURPOSE This study aimed to evaluate the accuracy of digitizing dental impressions of abutment teeth using a white light scanner and to compare the findings among teeth types. MATERIALS AND METHODS To assess precision, impressions of the canine, premolar, and molar prepared to receive all-ceramic crowns were repeatedly scanned to obtain five sets of 3-D data (STL files). Point clouds were compared and error sizes were measured (n=10 per type). Next, to evaluate trueness, impressions of teeth were rotated by 10°-20° and scanned. The obtained data were compared with the first set of data for precision assessment, and the error sizes were measured (n=5 per type). The Kruskal-Wallis test was performed to evaluate precision and trueness among three teeth types, and post-hoc comparisons were performed using the Mann-Whitney U test with Bonferroni correction (?=.05). RESULTS Precision discrepancies for the canine, premolar, and molar were 3.7 µm, 3.2 µm, and 7.3 µm, respectively, indicating the poorest precision for the molar (P<.001). Trueness discrepancies for teeth types were 6.2 µm, 11.2 µm, and 21.8 µm, respectively, indicating the poorest trueness for the molar (P=.007). CONCLUSION In respect to accuracy the molar showed the largest discrepancies compared with the canine and premolar. Digitizing of dental impressions of abutment teeth using a white light scanner was assessed to be a highly accurate method and provided discrepancy values in a clinically acceptable range. Further study is needed to improve digitizing performance of white light scanning in axial wall. PMID:25551007

Jeon, Jin-Hun; Kim, Hae-Young; Kim, Ji-Hwan

2014-01-01

379

In vivo Study of the Accuracy of Dual-arch Impressions  

PubMed Central

Background: This study evaluated in vivo the accuracy of metal (Smart®) and plastic (Triple Tray®) dual-arch trays used with vinyl polysiloxane (Flexitime®), in the putty/wash viscosity, as well as polyether (Impregum Soft®) in the regular viscosity. Materials and Methods: In one patient, an implant-level transfer was screwed on an implant in the mandibular right first molar, serving as a pattern. Ten impressions were made with each tray and impression material. The impressions were poured with Type IV gypsum. The width and height of the pattern and casts were measured in a profile projector (Nikon). The results were submitted to Student’s t-test for one sample (? = 0.05). Results: For the width distance, the plastic dual-arch trays with vinyl polysiloxane (4.513 mm) and with polyether (4.531 mm) were statistically wider than the pattern (4.489 mm). The metal dual-arch tray with vinyl polysiloxane (4.504 mm) and with polyether (4.500 mm) did not differ statistically from the pattern. For the height distance, only the metal dual-arch tray with polyether (2.253 mm) differed statistically from the pattern (2.310 mm). Conclusion: The metal dual-arch tray with vinyl polysiloxane, in the putty/wash viscosities, reproduced casts with less distortion in comparison with the same technique with the plastic dual-arch tray. The plastic or metal dual-arch trays with polyether reproduced cast with greater distortion. How to cite the article: Santayana de Lima LM, Borges GA, Burnett LH Jr, Spohr AM. In vivo study of the accuracy of dual-arch impressions. J Int Oral Health 2014;6(3):50-5. PMID:25083032

de Lima, Luciana Martinelli Santayana; Borges, Gilberto Antonio; Junior, Luiz Henrique Burnett; Spohr, Ana Maria

2014-01-01

380

Stress strengthens memory of first impressions of others' positive personality traits.  

PubMed

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, André; Oitzl, Melly S; Schachinger, Hartmut

2011-01-01

381

Properties of the tray adhesive of an addition polymerizing silicone to impression tray materials.  

PubMed

Adhesive bond strength studies for the tray adhesive of an addition vinyl polysiloxane (President) impression material were conducted with an acrylic resin, chromium-plated brass, and plastic trays. Tensile and shear stress studies were performed on the Instron Universal testing machine. Acrylic resin specimens roughened with 80-grit silicon carbide paper exhibited appreciably higher bond strengths compared with different types of tray material and methods of surface preparation. PMID:1805022

Sulong, M Z; Setchell, D J

1991-12-01

382

A microbiological investigation following the disinfection of alginate and addition cured silicone rubber impression materials.  

PubMed

The antimicrobial efficacy of four commercially available disinfectants (Haz-tabs, chlorhexidine, Virkon and C&J Algisept Spray) was investigated. It was shown that all were effective in decontaminating the impressions whilst those placed only in sterile water, used as a control, showed variable levels of bacterial growth. Moreover, alginate appeared to carry significantly higher numbers of bacteria than addition cured silicone rubber. PMID:10218013

al-Omari, W M; Jones, J C; Hart, P

1998-09-01

383

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

384

Knowledge and impressions regarding the concept of mutation among Japanese university students.  

PubMed

Although the term mutation is frequently used in genetic counseling, it may carry negative connotations and create misunderstanding. Our objective was to investigate the relationship between the impressions regarding three Japanese terms mutation of gene, change of gene, and lesion of gene as well as to investigate the depth of understanding regarding mutation. A total of 175 university students and auditing students were included and responded to two questionnaires that were Impressions regarding the term in the semantic differential method and Knowledge about the concept of mutation. In factor analysis, three factors (Value, Change Rate, and Intention) were extracted. Participants were divided into three groups depending on their knowledge, and a two-way analysis of variance (Term x Knowledge Group) was conducted on the factor score for each. Results showed that the main effect of the 'Term' was significant for the Value Factor and that interaction was significant for the Change Rate Factor, and that the main effect of Knowledge Group was significant for the Intention Factor. The findings suggest that healthcare professionals should demonstrate an awareness of varying impressions of the different terms used to refer to the identical concepts of mutation. This is of particular importance when communicating with patients and their families. PMID:18445045

Ando, N; Saito, Y; Takemura, K; Takada, F; Iwamitsu, Y

2008-07-01

385

A Comparative Evaluation of the Dimensional Stability of Three Different Elastomeric Impression Materials after Autoclaving – An Invitro Study  

PubMed Central

Aim of the Study: The purpose of the study was to determine the effect of autoclaving on the dimensional stability of three different elastomeric impression materials at three different time intervals. Materials and Methods: Standardized stainless steel master die as per ADA specification number 19 was fabricated. The impression materials used for the study were condensation silicone (GP1), addition silicone (GP2) and polyether (GP3). A total of 45 samples of the stainless steel die were made (n = 45), that is 15 samples for each group. Impression materials were mixed according to the manufacturer’s instructions and were loaded into the mold to make an impression of the die. Impressions were identified with the help of numerical coding system and measurements were made using stereomicroscope (MAGNUS MSZ-Bi) of 0.65x magnification with the help of image analysis software (IMACE PRO-INSIGHT VERSION.The results were subjected to statistical analysis using one way analysis of variance and student t-test for comparison between the groups. Results: Within the limitations of the study statistically significant dimensional changes were observed for all the three impression materials at three different time intervals but this change was not clinically significant. Conclusion: It is well-known fact that all impressions should be disinfected to avoid possible transmission of infectious diseases either by direct contact or cross contamination. Immersion and spray disinfection as well as various disinfection solutions have been tested and proven to be effective for this purpose. But for elastomeric impression materials these methods have proven to be ineffective as they do not prevent cross contamination among the dental team. So autoclaving was one of the most effective sterilization procedure for condensation silicone and addition silicone. Since polyether is hydrophilic it is better to disinfect the impressions as recommended by the manufacturer or by immersion or spray atomization. PMID:25478447

Thota, Kiran Kumar; Ravuri, Rajyalakshmi; Tella, Suchita

2014-01-01

386

Antibacterial efficacy and effect of chlorhexidine mixed with irreversible hydrocolloid for dental impressions: a randomized controlled trial.  

PubMed

This study aimed to evaluate whether chlorhexidine mixed with irreversible hydrocolloid powder decreases microbial contamination during impression taking without affecting the resulting casts. Twenty volunteers were randomly divided into two groups (n = 10) according to the liquid used for impression taking in conjunction with irreversible hydrocolloid: 0.12% chlorhexidine or water. Surface roughness and dimensional stability of the casts were evaluated. Chlorhexidine mixed with irreversible hydrocolloid decreased the percentage of microorganisms when compared with water (P < .001) but did not affect the surface quality or dimensional stability of the casts. Mixing chlorhexidine with irreversible hydrocolloid powder is an alternative method to prevent contamination without sacrificing impression quality. PMID:25010881

Cubas, Glória; Valentini, Fernanda; Camacho, Guilherme Brião; Leite, Fábio; Cenci, Maximiliano Sérgio; Pereira-Cenci, Tatiana

2014-01-01

387

Cost-effectiveness of silicone and alginate impressions for complete dentures  

PubMed Central

Objective The aim of this study was to assess the cost effectiveness of silicone and alginate impressions for complete dentures. Methods Cost effectiveness analyses were undertaken alongside a UK single centre, double blind, controlled, crossover clinical trial. Taking the perspective of the healthcare sector, effectiveness is measured using the EuroQol (EQ-5D-3L) which provides a single index value for health status that may be combined with time to produce quality adjusted life years (QALYs); and Oral Health Impact Profile (OHIP-EDENT). Incremental cost effectiveness ratios are presented representing the additional cost per one unit gained. Results Mean cost was higher in the silicone impression group (£388.57 vs. £363.18). Negligible between-group differences were observed in QALY gains; the silicone group had greater mean OHIP-EDENT gains. The additional cost using silicone was £3.41 per change of one point in the OHIP-EDENT. Conclusions The silicone group was more costly, driven by the cost of materials. Changes in the EQ-5D and QALY gains over time and between arms were not statistically significant. Change in OHIP-EDENT score showed greater improvement in the silicone group and the difference between arms was statistically significant. Given negligible QALY gains and low level of resource use, results must be treated with caution. It is difficult to make robust claims about the comparative cost-effectiveness. Clinical significance Silicone impressions for complete dentures improve patients’ quality of life (OHIP-EDENT score). The extra cost of silicone impressions is £30 per patient. Dentists, patients and health care funders need to consider the clinical and financial value of silicone impressions. Different patients, different dentists, different health funders will have individual perceptions and judgements. ISRCTN01528038. NIHR-RfPB grant PB-PG-0408-16300.?? This article forms part of a project for which the author (TPH) won the Senior Clinical Unilever Hatton Award of the International Assocation for Dental Research, Capetown, South Africa, June 2014. PMID:24995472

Hulme, C.; Yu, G.; Browne, C.; O’Dwyer, J.; Craddock, H.; Brown, S.; Gray, J.; Pavitt, S.; Fernandez, C.; Godfrey, M.; Dukanovic, G.; Brunton, P.; Hyde, T.P.

2014-01-01

388

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

389

Effect of pentaerythritol and organic tin with calcium\\/zinc stearates on the stabilization of poly(vinyl chloride)  

Microsoft Academic Search

The stabilization effect of calcium and zinc stearates (CaSt2\\/ZnSt2) combined with pentaerythritol (PeE) and organic tin on poly(vinyl chloride) was investigated. The results show that the addition of calcium\\/zinc stearates combined with PeE and organic tin can improve thermal and colour stability of poly(vinyl chloride) in both static and dynamic tests. Mechanisms for improving stability of PVC are also discussed.

Ming Wang; Jiayou Xu; Hong Wu; Shaoyun Guo

2006-01-01

390

Preparation of polyvinyl alcohol–silica hybrid heterogeneous anion-exchange membranes by sol–gel method and their characterization  

Microsoft Academic Search

Polyvinyl alcohol–silica hybrid heterogeneous anion-exchange membranes were prepared by sol–gel method by dispersing the anion-exchange resin in the gel formed by acid\\/base hydrolysis of tetraethylorthosilicate in polyvinyl alcohol solution. The effect of acid and base-catalyzed hydrolysis on membrane preparation and extent of resin loading was studied. Various membranes were prepared with 60% (w\\/w) anion-exchange resin (Indoin FFIP) loaded with different

R. K. Nagarale; Vinod K. Shahi; R. Rangarajan

2005-01-01

391

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

392

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

393

In vitro and in vivo evaluation of the estrogenic, androgenic, and progestagenic potential of two cyclic siloxanes.  

PubMed

The purpose of these experiments was to determine the potential estrogenic, androgenic, and progestagenic activity of two cyclic siloxanes, octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5). Receptor-binding experiments and a luciferase reporter gene assay were used to determine if the materials were able to bind and activate either the estrogen receptors (ERs) or progesterone receptors (PRs)-alpha or beta. The rat uterotrophic assay (RUA) for estrogenic activity and the Hershberger assay for androgenic activity were utilized as the in vivo assays. For the ER-binding studies, D4 was shown to bind to ERalpha but not to ERbeta. D5 did not bind to either of the two receptors. D4 activated the reporter gene at 10 microM, while D5 was considered negative in the estrogen reporter gene assay. Neither material was a ligand for the PRs. Both the RUA and Hershberger assays were conducted using whole-body inhalation of the two materials for 16 h/day. D4 resulted in a small but significant increase in both wet and blotted uterine weight as well as increases in both luminal and glandular epithelial cell height in both Sprague Dawley and Fischer 344 rats. D5 was negative in both rat strains, indicating that D5 does not possess estrogenic activity. Neither material possessed any significant antiestrogenic activity. Both materials were negative in the Hershberger assay indicating that neither material possesses any significant androgenic activity. Our studies have shown that D4 exhibits a low affinity for ERalpha in vitro and a weakly estrogenic response in vivo. PMID:17175556

Quinn, Anne L; Regan, Jane M; Tobin, Joseph M; Marinik, Brian J; McMahon, Joan M; McNett, Debra A; Sushynski, Christopher M; Crofoot, Steven D; Jean, Paul A; Plotzke, Kathleen P

2007-03-01

394

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

NASA Astrophysics Data System (ADS)

Bottom Anti Reflective Coating (BARC) materials are generally used to minimize reflection of incident light from the substrate (Rsub). As IC manufactures move to high NA systems to meet the patterning requirements for next generation technology as well as the use of new lower dielectric constant materials in the back-end-of-line dielectric, the requirements for developing BARC materials with new properties such as faster strip rate and properly tuned optical properties (n = refractive index and k=extinction coefficient) are essential. Some photoresist patterning schemes may also require a dual BARC system such as tri-layer patterning (TLP), which is undergoing extensive evaluation in academia and industries. This work focuses on Honeywell's next generation DUO193 material (DUO193FS), which is a siloxane-based polymer with an organic 193 nm chromophore attached to it. The effects of additives for adjusting strip rate in a wet chemical stripper, while maintaining chemical resistance to a photoresist developer, 2.38% TMAH in water are discussed. Different spectroscopic studies are performed to elucidate the mechanism of faster strip rate. Solvation of silanol groups and their orientation in the presence of additives are found to be secondary mechanism. The primary reason for enhanced strip rate is attributed to the addition of additives A and B, which lower bulk density of the solid film. DUO193FS can be stand alone BARC or used with another BARC as part of a dual BARC system to further minimize Rsub, maintaining resistance to 2.38% TMAH, planarizing any underlying topography and keeping the final film strip rate high.

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

2009-03-01

395

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

396

Polyvinyl alcohol as a biocompatible alternative for the passivation of gold nanorods.  

PubMed

The functionalization of gold nanorods (GNRs) with polymers is essential for both their colloidal stability and biocompatibility. However, a bilayer of the toxic cationic surfactant cetyl trimethylammonium bromide (CTAB) adsorbed on the nanorods complicates this process. Herein, we report on a strategy for the biocompatible functionalization of GNRs with a hydrophobic polymeric precursor, polyvinyl acetate, which is then transformed into its hydrophilic analogue, polyvinyl alcohol. This polymer was chosen due to its well-established biocompatibility, tunable "stealth" properties, tunable hydrophobicity, and high degree of functionality. The biocompatibility of the functionalized GNRs was tested by exposing them to primary human blood monocyte derived macrophages; the advantages of tunable hydrophobicity were demonstrated with the long-term stable encapsulation of a model hydrophobic drug molecule. PMID:25056839

Kinnear, Calum; Burnand, David; Clift, Martin J D; Kilbinger, Andreas F M; Rothen-Rutishauser, Barbara; Petri-Fink, Alke

2014-11-10

397

Bonding, vibrational, and electrical characteristics of CdS nanostructures embedded in polyvinyl alcohol matrix  

SciTech Connect

CdS nanocomposites have been grown in polyvinyl alcohol matrix by a chemical synthesis process. The transmission electron micrographs of nanocomposites synthesized at 70-90 deg. C temperature showed the growth of needlelike and junctionlike nanostructures. X-ray photoelectron spectroscopy analysis revealed the growth of stoichiometric CdS without the formation of any intermediate phases at the CdS-polyvinyl alcohol interface. Raman spectra of first order longitudinal optical phonon peak has been analyzed using phonon dispersion model to detect the surface phonon modes in CdS nanoneedles and wires. The origin of negative differential resistance behavior in current-voltage characteristics for junctionlike CdS nanocomposites has been discussed.

Mondal, S. P.; Dhar, A.; Ray, S. K. [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur-721 302 (India); Chakraborty, A. K. [Laboratory for Mechanical Systems Engineering EMPA, Duebendorf, Zurich, CH-8600 (Switzerland)

2009-04-15

398

Polyvinyl alcohol-coated hybrid fiber grating for relative humidity sensing  

NASA Astrophysics Data System (ADS)

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.

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

2011-07-01

399

The use of filter paper plasticized with polyvinyl alcohol-glutaraldehyde in ELISA.  

PubMed

F1-antigen purified from Yersinia pestis was covalently linked to 5-mm diameter filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde. These discs were used both for ELISA and dot-ELISA for the detection of anti-F1 IgG in rabbits. The best conditions were achieved using 1.25 microg of F1 antigen/disc, 3% w/v skim milk in PBS as blocking agent, anti-IgG peroxidase conjugate diluted 12,000 times, and serum from rabbits immunized or not against Y. pestis, diluted 6,400 times. The absorbance values obtained from the comparative study between this procedure and conventional ELISA were not significantly different but the low cost of the reagents employed in ELISA using the filter paper discs plasticized with polyvinyl alcohol-glutaraldehyde makes this method economically attractive. PMID:10881058

Barbosa, G H; Santana, E M; Almeida, A M; Araujo, A M; Fatibello-Filho, O; Carvalho, L B

2000-07-01

400

Radiation chemical reduction of heptylviologens in polyvinyl alcohol under the action of x-radiation  

SciTech Connect

This paper presents an investigation of the radiation-chemical reduction of heptylviologen (HV/sup 2 +/) in a polyvinyl alcohol matrix; the method of steady-state radiolysis was used in the investigation. It was shown that the main radiolysis products of heptylviologen are the radical cations HV/sup +/. Their concentration passes through a maximum as the absorbed dose is increased. The radiation-chemical yield depends on the concentration of HV/sup 2 +/ and is equal to 18+/-2 at (HV/sup 2 +/) = 1.10/sup -1/ mole/dm/sup 3/. Radicals arising under the action of ionizing radiation on polyvinyl alcohol, in addition to electrons, participate in the reduction of HV/sup 2 +/.

Kolotilkin, A.S.; Krainov, I.P.; Mal'tsev, E.I.

1986-03-01

401

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

SciTech Connect

It has been shown that sorbents synthesized from polyvinyl alcohol (PVA) and polyvinyl glycol (PVG) are the most effective agents for extraction of boron from natural waters and brines. The action of such sorbents is based on the ability of boric acid to form stable complexes with polyhydroxy compounds. In this work the authors studied hydroxylic sorbents differing in OH-group contents and in the amounts and nature of the cross-linking agent. The principal characteristics of the sorbents studied are given. The theoretical capacity was calculated on the assumption that the structural unit sorbing one boric acid molecule is -CH/sub 2/-CHOH-CH/sub 2/CHOH- in PVA and -CHOH-CHOH- in PVG.

Kisel'gof, G.V.; Arkhangel'skii, L.K.; Bochkova, N.A.

1986-10-10

402

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

403

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

SciTech Connect

The release of diethylhexyl phthalate (DEHP) from flexible polyvinyl chloride containers into intravenous cyclosporine solutions was studied. Intravenous cyclosporine solution or solutions containing the vehicle Cremophor EL and alcohol in dextrose were prepared in an all-glass system and stored in polyvinyl chloride (PVC) bags. Four samples were obtained at different time intervals, and DEHP content was analyzed by gas chromatography. The amount of DEHP that was leached into solutions stored in the PVC bags increased as storage time increased. By 48 hours, nearly 33 mg of DEHP had leached into the solution. Intravenous cyclosporine solutions should be prepared in glass containers to minimize patient exposure to DEHP. If plastic bags are used for preparing cyclosporine injections, the injections must be used immediately after preparation.

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

1986-11-01

404

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

405

A sectional-splinting technique for impressing multiple implant units by eliminating the use of an open tray.  

PubMed

Since the inception of root form implant dentistry by P-I Branemark in the early 1980's, so many technical advances have been put forward by several authors. However, the open tray impression technique is still performed for impressing multiple implant fixtures as it was first described in the original Branemark procedure manual. The most critical aspect for a successful implant-supported restoration is the passive and an accurate fit of superstructures to avoid preload and loading stresses. Splinting impression technique in multiple implants has gained popularity. Auto-polymerizing acrylic resin is among the most routinely practiced splinting material for multiple implant units. However, unfortunately, it exhibits shrinkage, which makes an impression quite inaccurate. This case report presents the solution to minimize the shrinkage of resin by utilizing sectional-splinting technique as advocated in the previous implant literature. PMID:24963251

Deogade, Suryakant C; Dube, Gunjan

2014-04-01

406

All solid-state electric double-layer capacitors based on alkaline polyvinyl alcohol polymer electrolytes  

Microsoft Academic Search

Solid-state electrochemical double-layer capacitors (ELDCs) based on alkaline polyvinyl alcohol (PVA) solid polymer electrolytes (SPEs) are prepared. Electrochemical capacitance performance of these capacitors is studied by cyclic voltammetry, galvanostatic charge–discharge testing, and ac impedance spectroscopy. For comparison, two types of EDLC cells are constructed and tested. It is found that an EDLC with a PVA polymer electrolyte exhibits much higher

Chun-Chen Yang; Sung-Ting Hsu; Wen-Chen Chien

2005-01-01

407

Characterization of hydrogels formed from acrylate modified poly(vinyl alcohol) macromers  

Microsoft Academic Search

Poly(vinyl alcohol) was modified with pendent acrylate groups to form a macromer that was crosslinked via photopolymerization. Polymerization behavior was studied for several initial macromer concentrations using DSC and Near-IR spectroscopy. Under mild photoinitiating conditions (e.g. 0.05wt% initiator and less than 20mW\\/cm2 of 365nm light), the hydrogels polymerized to 100% conversion in less than 5min. To characterize the network structure,

P. Martens; K. S. Anseth

2000-01-01

408

Photoluminescence and far-infrared spectroscopy of PbS quantum dots – Polyvinyl alcohol nanocomposite  

Microsoft Academic Search

The nanocomposite consisting of PbS quantum dots with average diameter of 26Å and polyvinyl alcohol was characterized using photoluminescence and far-infrared spectroscopy. Photoluminescence spectra of nanocomposite, measured in temperature range from 8 to 280K, consists of broad peak which spans the energy range from 1.2 to 2.1eV and can be connected with trap states inside the band gap. Far-infrared measurements

R. Kostic; M. Romcevic; N. Romcevic; L. Klopotowski; J. Kossut; J. Kuljanin-Jakovljevic; M. I. ?omor; J. M. Nedeljkovi?

2008-01-01

409

Preparation of PVP (polyvinyl pyrrolidone)\\/Ba-Sr hexaferrites via gel to crystalline method  

Microsoft Academic Search

Ba-M and Sr-M-type hexagonal ferrites have been prepared via a sol–gel route, and the effects of adding different amounts of polyvinyl pyrrolidone (PVP) into the sol solutions. The average crystallite, size, D and ?, was obtained as for Z13 = 22 ±2 nm and Z13–2 = 16±3 nm and for Z16 = 18±7 nm and Z16–2 = 17±5 nm by XRD. FT-IR and TG

Z. Durmus; A. Baykal; H. Sozeri; M. S. Toprak

2012-01-01

410

Radiation grafting of hydrophilic monomers on to plasticized poly(vinyl chloride) sheets  

Microsoft Academic Search

Medical-grade plasticized poly(vinyl chloride) (PVC) sheets were surface modified using gamma-radiation grafting of a combination of hydrophilic monomers based on 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP). The modified surfaces were evaluated for their surface properties using contact angle measurements, phase-contrast photomicroscopy and scanning electron microscopy. Surface energy calculations of the modified surfaces indicated that the surfaces became highly hydrophilic

V. Kalliyana Krishnan; A. Jayakrishnan; Joseph D. Francis

1990-01-01

411

Migration of Epoxidized Sunflower Oil and Dioctyl Phthalate from Rigid and Plasticized Poly(vinyl chloride)  

Microsoft Academic Search

The aim of this paper is the determination of the specific migration of epoxidized sunflower oil (ESO) from rigid and plasticized poly(vinyl chloride) (PVC) into food simulants. ESO was obtained by epoxidation of commercial sunflower oil and used as a thermal organic co-stabilizer for PVC. For that purpose, rigid and plasticized (0, 15, 30, and 45 wt% of dioctyl phthalate or

D. Atek; N. Belhaneche-Bensemra; M. Turki

2010-01-01

412

Radiation grafting of hydrophilic monomers onto plasticized poly(vinyl chloride) sheets  

Microsoft Academic Search

Medical grade poly(vinyl chloride) (PVC) sheets were surface modified by grafting a combination of 2-hydroxyethyl methacrylate (HEMA) and N-vinyl pyrrolidone (NVP) or NVP alone using gamma radiation in an effort to retard the migration of the plasticizer from the PVC matrix. Presence of cupric ions at a concentration of 0.005m was found to be optimal in not only preventing the

V. Kalliyana Krishnan; A. Jayakrishnan; J. D. Francis

1991-01-01

413

Aromatic 1,3,4-oxadiazoles as thermal stabilizers for rigid poly(vinyl chloride)  

Microsoft Academic Search

Several aromatic 1,3,4-oxadiazole derivatives have been investigated as thermal stabilizers for rigid poly(vinyl chloride) (PVC) at 180°C in air. Their stabilizing efficiencies are evaluated by measuring the rate of dehydrochlorination and the extent of discoloration of the degraded polymer. The results obtained show the greater stabilizing efficiency of the investigated compounds as compared with dibasic lead carbonate (DBLC), barium-cadmium-zinc stearate

Nadia Ahmed Mohamed; Eljazi I. Al-afaleq

1999-01-01

414

Influence of gamma-radiation on the optical properties of modified polyvinyle chloride  

NASA Astrophysics Data System (ADS)

The optical absorption spectra of polyvinyle chloride, PVC, doped with Cd and Pb is presented. The effect of ? radiation doses in range of 2?200 Mrad on the fundamental absorption edge ?g was determined. On the basis of quantitative analysis of obtained data, the calculated absorption coefficient, ?, the absorption index, K, and the optical energy gap Eopt, were found to be radiation and dopant dependent. The results are discussed on the basis of the radiation induced degradiation of PVC.

Madi, N. K.; Taleb, W. M. Abou; Rehim, N. Abdel; Kassem, M. E.

1994-06-01

415

Strong and ductile poly(vinyl alcohol)\\/graphene oxide composite films with a layered structure  

Microsoft Academic Search

We report the preparation of mechanically strong and ductile poly(vinyl alcohol)\\/graphene oxide (GO) composite films with a layered structure simply by vacuum filtration. The Young’s modulus and tensile yield strength of the composite film containing 3wt.% GO were measured to be 4.8GPa and 110±7MPa, respectively. Furthermore, it is flexible and exhibits a large elongation at break (36±4%). The high mechanical

Yuxi Xu; Wenjing Hong; Hua Bai; Chun Li; Gaoquan Shi

2009-01-01

416

Hollow Fiber Ultrafiltration Membranes from Poly(Vinyl Chloride): Preparation, Morphologies, and Properties  

Microsoft Academic Search

Hollow fiber poly(vinyl chloride) membranes were prepared by using the dry\\/wet spinning method. Cross-section, internal, and external surfaces of the hollow fibers structure were studied by SEM. The pore size and pore size distribution of the hollow fibers were measured by a PMI capillary flow porometer. UF experiments of pure water and aqueous solution of PVP K-90 were carried out.

Qusay Alsalhy; Sufyan Algebory; Ghanim M. Alwan; S. Simone; A. Figoli; E. Drioli

2011-01-01

417

The use of polyvinyl alcohol glutaraldehyde antigen coated discs for laser induced fluorescence detection of plague  

Microsoft Academic Search

F1-antigen purified from Yersinia pestis was covalently linked to polyvinyl alcohol (PVA) glutaraldehyde cross-linked discs synthesized by acid catalysis. This derivative was incubated with fluorescein labeled antibody against F1-antigen and excited at 4880 Å by either an argon laser or a dye laser. The fluorescence was detected at 5200 Å. The appearance of the transition at 5200 Å was indicative

L. B. Carvalho; A. M. Araujo; A. M. P. Almeida; W. M. Azevedo

1996-01-01

418

Encapsulation and release of rifampicin using poly(vinyl pyrrolidone)-poly(methacrylic acid) polyelectrolyte capsules  

Microsoft Academic Search

Poly(vinyl pyrrolidone) and poly(methacrylic acid) multilayer capsules based on hydrogen bonding have been prepared by the layer-by-layer approach and used to encapsulate and release rifampicin, an anti-tuberculosis drug. Removal of silica core using a buffer of ammonium fluoride and hydrofluoric acid at about pH 3 was found to produce better capsules than hydrofluoric acid alone. An eight-layered capsule had a

K. N. Anil Kumar; S. Basu Ray; V. Nagaraja; Ashok M. Raichur

2009-01-01

419

Surface and interfacial activities of hydrophobically modified poly(vinyl alcohol) (PVA)  

Microsoft Academic Search

In the present study, the air-liquid surface and liquid-liquid interfacial activities of hydrophobically modified poly(vinyl alcohol) (PVA) solutions were investigated to determine the effects of NaCl concentration, polymer concentration, time, polymer molecular weight, polymer modification and the average length of the hydrophobic side groups. The hydrophobically modified PVA exhibit high air-liquid surface and liquid-liquid interfacial activities which increase with increasing

Garba O. Yahya; S. K. Asrof Ali; Esam Z. Hamad

1996-01-01

420

Film dosimeters based on methylene blue and methyl orange in polyvinyl alcohol  

SciTech Connect

Polyvinyl alcohol (PVA) films containing methylene blue and methyl orange are useful as gamma and electron radiation dosimeters. Absorbed doses should not exceed 40 kGy for methylene blue and 500 kGy for methyl orange. Because PVA is water-soluble, the films may be made without toxic solvents. The effects of irradiation temperature and humidity on the radiation response of the dosimeter films are discussed.

Chung, W.H. (Pusan National Univ. (Korea, Republic of). Dept. of Physics); Miller, A. (Risoe National Lab., Roskilde (Denmark))

1994-05-01

421

Congo red/polyvinyl alcohol film dosimeter for gamma rays and electrons  

SciTech Connect

Polyvinyl alcohol films containing congo red are useful as gamma and electron radiation dosimeters. Absorbed doses should not exceed 500 kGy. The dose response is rather linear in a higher range, e.g., 100 to 500 kGy. The film is relatively stable before and after irradiation for quite a long time against fading, for example, a change of [approximately]10% in 1 yr following irradiation at room temperature.

Woon Hyuk Chung (Pusan National Univ. (Korea, Republic of). Dept. of Physics)

1994-03-01

422

Properties and sorption studies of chitosan–polyvinyl alcohol blend films  

Microsoft Academic Search

Chitosan–polyvinyl alcohol (PVA) blend films were prepared and characterized for mechanical and optical properties. Intermolecular interaction between chitosan–PVA blend was investigated using FTIR. Moisture sorption characteristics of chitosan–PVA blend at 25 °C were studied for water activities ranging from 0.11 to 0.92. The moisture content increased with increase in PVA concentration. The moisture sorption data were used to fit eight

P. C. Srinivasa; M. N. Ramesh; K. R. Kumar; R. N. Tharanathan

2003-01-01

423

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

424

Nucleation of polyvinyl alcohol crystallization by single-walled carbon nanotubes  

Microsoft Academic Search

Non-isothermal crystallization experiments were performed on poly(vinyl alcohol) mixed with single-walled carbon nanotubes. Non-isothermal crystallization experiments showed that nanotubes nucleate crystallinity at weight fractions as low as 0.1%. An Ozawa model was applied to the non-isothermal crystallization data, and this approach confirmed the results deduced from the qualitative examination of the data: there was a clear difference in crystallization kinetics

Olga Probst; Eric M. Moore; Daniel E. Resasco; Brian P. Grady

2004-01-01

425

UV-sensitive indicators based on bromophenol blue and chloral hydrate dyed poly(vinyl butyral)  

Microsoft Academic Search

UV-sensitive indicators based on dyed poly(vinyl butyral) (PVB) containing acid-sensitive dye (bromophenol blue, BPB) and chloral hydrate have been developed and used successfully to measure the integrated UV irradiance. This flexible film changes colour from blue to green and finally to yellow on exposure to UV irradiation. The radiation-induced change in colour was analysed spectrophotometrically at the absorption band maxima

A. A. Abdel-Fattah; M. El-Kelany; F. Abdel-Rehim; A. A. El Miligy

1997-01-01

426

High-dose film dosimeters based on bromophenol blue or xylenol orange dyed polyvinyl alcohol  

Microsoft Academic Search

Dyed poly(vinyl alcohol) (PVA) films, prepared by a simple technique of casting acqueous solutions of PVA containing bromophenol blue (BPB) or xylenol orange (XYO) on a horizontal glass plate, are useful as routine high-dose dosimeters. These flexible plastic film dosimeters are bleached when exposed to ?-ray photons. Absorbed doses should not exceed 20 kGy for BPB\\/PVA film and 90 kGy

A. A. Abdel-Fattah; S. Ebraheem; M. El-Kelany; F. Abdel-Rehim

1996-01-01

427

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

428

The effect of pouring time on the dimensional accuracy of casts made from different irreversible hydrocolloid impression materials  

PubMed Central

Aims and Objectives: To determine the time dependent accuracy of casts made from three different irreversible hydrocolloids. Materials and Methods: The effect of delayed pouring on the accuracy of three different irreversible hydrocolloid impression materials – Regular set CA 37(Cavex, The Netherlands), regular set chromatic (Jeltrate, Dentsply), and fast set (Hydrogum soft, Zhermack Clinical) was investigated. A brass master die that contained two identical posts simulating two complete crown-tapered abutment preparations with reference grooves served as a standardized master model. A total of 120 impressions were made using specially prepared stock-perforated brass tray with 40 impressions of each material. The impressions were further sub-grouped according to four different storage time intervals: 0 min (immediately), 12 min, 30 min, and 1 h. The impressions were stored at room temperature in a zip-lock plastic bag. Interabutment and intraabutment distances were measured in the recovered stone dies (Type IV, Kalrock) using a profile projector with an accuracy of 0.001 mm. The data so obtained was analyzed statistically. Results: Results of this study showed no statistically significant differences in the accuracy of casts obtained at different time intervals. Conclusion: Because it is not always possible to pour the impression immediately in routine clinical practice, all irreversible hydrocolloid materials studied could be stored in a zip-lock plastic bag for upto 1 h without any significant distortion. PMID:24124296

Wadhwa, Supneet Singh; Mehta, Richa; Duggal, Nidhi; Vasudeva, Kamlesh

2013-01-01

429

Amelanotic corneally displaced malignant conjunctival melanoma: a case report evaluated with impression cytology.  

PubMed

Here we describe the case of a 65-year-old Caucasian female who presented with an amelanotic malignant conjunctival melanoma and highlight the clinical and pathological features of this rare entity that displayed exclusive corneal invasive growth without evidence of conjunctival tumors other than primary acquired melanosis. Impression cytology aided in the initial diagnosis. The patient underwent surgical treatment. Histopathology and immunohistochemistry revealed an invasive amelanotic melanoma limited to the cornea and exhibiting S-100, Melan A, and HMB-45 positivity. The absence of pigmentation delayed early clinical detection and treatment. Awareness of this nonpigmented melanoma is important for early recognition and appropriate management. PMID:25076376

Barros, Jeison de Nadai; Motono, Márcia; Costa, Felipe D'Almeida; da Cunha, Marcelo Carvalho; Chojniak, Martha Motono

2014-01-01

430

Disinfection of alginate impression material using disinfectants as mixing and soak solutions.  

PubMed

Disinfectant solutions were used as water substitutes in the preparation of specimens of alginate impression material. Chlorhexidine gluconate and sodium peroxysulphate solutions were tested. The alginate specimens were infected by sucking, subsequently disinfected in the solution used in the alginate preparation, and then tested for infectivity by 24-h incubation in thioglycollate broth. Bacterial growth was measured by changes in turbidity using a turbidimeter. The results indicate that chlorhexidine gluconate is an effective alginate disinfectant, when it is used as the liquid for alginate preparation and post-setting disinfection solution. PMID:1787216

Touyz, L Z; Rosen, M

1991-08-01

431

A quantitative study of the effects of different grades of polyvinyl alcohol on the activities of certain enzymes in unfixed tissue sections  

Microsoft Academic Search

Synopsis  Different grades of the colloid stabilizer, polyvinyl alcohol, used for protecting unfixed cryostat sections during cytochemical reactions, may have different effects on enzymatic activity. The influence of three grades of polyvinyl alcohol on the activities of soluble, membrane-bound and membrane-enclosed enzymes has been investigated in unfixed sections; the activities were measured microdensitometrically.The largest molecular weight polyvinyl alcohol (G18\\/140, mol. wt.

B. Henderson; N. Loveridge; W. R. Robertson

1978-01-01

432

Study of the complexation of iron (III) and iron (II) with thioamidated copolymers based on polyvinyl alcohol and polyacrylonitrile by Moessbauer spectroscopy  

SciTech Connect

The mechanism of the interaction of iron(III) with polymeric ligands of vibrous structure, viz., polyvinyl alcohol (PVA), a copolymer of polyvinyl alcohol and polyacrylonitrile (PVA-PAN), and a thioamidated copolymer of polyvinyl alcohol and polyacrylonitrile (PVA-PAN-T), has been established by Moessbauer spectroscopy. It has been found that Fe(III) is partially or completely reduced to Fe(II) during sorption and that both forms of iron coordinate the oxygen-containing functional groups of the polymers.

Turte, K.I.; Yakubov, K.M.; Sokhibov, S.S.; Kalontarova, E.Ya.; Kalontarov, I.Ya.

1988-04-01

433

Impression management ("lie") scales are associated with interpersonally oriented self-control, not other-deception.  

PubMed

This article explores the status of impression management (IM) scales ("lie scales," notably, BIDR-IM) as measures of response bias, offers theory-driven substantive meaning to them, and compares them with self-deception enhancement (SDE). Study 1 (N?=?99) compared self-descriptions of actual self and ideal self given in a non-anonymous setting. High similarity indicates self-enhancement. Study 2 (70 dyads) analyzed self-other agreement about IM and SDE. Agreement indicates substantive basis to the scales' scores. Study 3 (N?=?182) explored the centrality of self-control in the self-perception of individuals varying in IM and SDE. Study 4 (95 dyads) corroborated self-reports about self-control using informants' reports. In Study 1, IM was associated with relative humility, whereas SDE was associated with self-enhancement. In Study 2, strong self-other agreement was found only for IM, indicating that high IM (but not SDE) is grounded in real-life behavior. In Study 3, self-control was central in the self-perception of high IM and high SDE individuals. In Study 4, strong relations with self-control were corroborated by informants only for IM. IM scales measure substantive content associated with self-control aimed at social adaptation, whereas the SDE scale depicts individuals with a grandiose self-perception, who fail to impress knowledgeable others. PMID:23750550

Uziel, Liad

2014-06-01

434

Late Carboniferous paleoichnology reveals the oldest full-body impression of a flying insect.  

PubMed

Insects were the first animals to evolve powered flight and did so perhaps 90 million years before the first flight among vertebrates. However, the earliest fossil record of flying insect lineages (Pterygota) is poor, with scant indirect evidence from the Devonian and a nearly complete dearth of material from the Early Carboniferous. By the Late Carboniferous a diversity of flying lineages is known, mostly from isolated wings but without true insights into the paleoethology of these taxa. Here, we report evidence of a full-body impression of a flying insect from the Late Carboniferous Wamsutta Formation of Massachusetts, representing the oldest trace fossil of Pterygota. Through ethological and morphological analysis, the trace fossil provides evidence that its maker was a flying insect and probably was representative of a stem-group lineage of mayflies. The nature of this current full-body impression somewhat blurs distinctions between the systematics of traces and trace makers, thus adding to the debate surrounding ichnotaxonomy for traces with well-associated trace makers. PMID:21464315

Knecht, Richard J; Engel, Michael S; Benner, Jacob S

2011-04-19

435

Assessing Impression Management With the MMPI-2 in Child Custody Litigation.  

PubMed

Forensic psychological evaluation of parents in child custody litigation is primarily focused on evaluating parenting capacity and underreporting. The biased responses of underreporting have been classified as Impression Management (IM) or as Self-Deceptive Positivity (S-DP), which are regarded to be conscious or unconscious in nature, respectively. A field study was undertaken to assess impression management on the Minnesota Multiphasic Personality Inventory-2 (MMPI-2) in child custody cases, the accuracy of the MMPI-2 scales in classifying IM, and what parents in child custody litigation actually manipulate in terms of IM. A total of 244 parents in child custody litigation and 244 parents under standard instructions were administered the MMPI-2. The results revealed that the L, Mp, Wsd, and Od scales discriminated between both samples of parents; the rate of satisfactory classification (i.e., odds ratio ranged from 5.7 for Wsd to 23.3 for Od) and an incremental validity of Od over Mp and Wsd. As for the effects of IM, the results show IM effects in the Basic Clinical Scales, the Restructured Clinical Scales, the Personality Psychopathology Five Scales, the Content Scales, and the Supplementary Scales. The implications of the results are discussed in relation to the forensic evaluation of parents in child custody litigation. PMID:25410722

Arce, Ramón; Fariña, Francisca; Seijo, Dolores; Novo, Mercedes

2014-11-19

436

Miniaturized impression creep testing of ball grid array solder balls attached to microelectronic packaging substrates  

NASA Astrophysics Data System (ADS)

This article reports on the design and implementation of a miniaturized impression creep apparatus for characterizing the creep behavior of tiny solder balls attached to a ball grid array (BGA) microelectronic packaging substrate. The technique requires no special sample preparation, can probe individual solder balls, and proffers high data throughput by allowing numerous creep curves to be obtained from one substrate, as well as by minimizing the time required to achieve steady state creep. The apparatus reported here uses a 100-?m-diameter cylindrical WC punch to characterize the creep behavior of 750-?m-diameter BGA solder balls from ambient temperature to 423 K. A video imaging system facilitates precise alignment and placement of the indenter on the specimen at the test temperature. The possible effect of substrate curvature on the experimental solder creep curves was evaluated and was deemed to be insignificant. Example creep curves and data based on 90Pb-10Sn BGA solder balls are presented. The test is further scalable for testing of smaller flip-chip joints, using a smaller punch. The present work reports on the implementation of impression creep for testing nonbulk specimens.

Pan, D.; Marks, R. A.; Dutta, I.; Mahajan, R.; Jadhav, S. G.

2004-12-01

437

Supercritical water oxidation of polyvinyl alcohol and desizing wastewater: influence of NaOH on the organic decomposition.  

PubMed

Polyvinyl alcohol is a refractory compound widely used in industry. Here we report supercritical water oxidation of polyvinyl alcohol solution and desizing wastewater with and without sodium hydroxide addition. However, it is difficult to implement complete degradation of organics even though polyvinyl alcohol can readily crack under supercritical water treatment. Sodium hydroxide had a significant catalytic effect during the supercritical water oxidation of polyvinyl alcohol. It appears that the OH- ion participated in the C-C bond cleavage of polyvinyl alcohol molecules, the CO2-capture reaction and the neutralization of intermediate organic acids, promoting the overall reactions moving in the forward direction. Acetaldehyde was a typical intermediate product during reaction. For supercritical water oxidation of desizing wastewater, a high destruction rate (98.25%) based on total organic carbon was achieved. In addition, cases where initial wastewater was alkaline were favorable for supercritical water oxidation treatment, but salt precipitation and blockage issues arising during the process need to be taken into account seriously. PMID:24520696

Zhang, Jie; Wang, Shuzhong; Guo, Yang; Xu, Donghai; Gong, Yanmeng; Tang, Xingying

2013-08-01

438

Effect of rinsing alginate impressions using acidic electrolyzed water on dimensional change and deformation of stone models.  

PubMed

This study investigated the effect of rinsing alginate impressions using acidic electrolyzed water on the dimensional change and deformation of stone models. Two brands of alginate impression materials were used. The impressions were rinsed using tap water or acidic electrolyzed water with a pH of 2.3, an oxidation-reduction potential of 1,230 mV, and a residual chlorine concentration of 45.0 ppm for 30 sec or 3 min. The sectional profiles of the stone models obtained from them were measured using a three-dimensional coordinate measuring system. For the same rinsing time, there was no significant difference in dimensional change between the two types of rinsing water. The change in shape from the master die was approximately the same for the stone models obtained from rinsed impressions using either water. The results suggest that the use of acidic electrolyzed water rather than tap water for rinsing is an acceptable treatment for alginate impressions. PMID:15005227

Hiraguchi, Hisako; Nakagawa, Hisami; Uchida, Hirobumi; Tanabe, Naoki

2003-12-01

439

Authority, Expertise, and Impression Management: Gendered Professionalization of Chemists in the Academy  

NASA Astrophysics Data System (ADS)

Women face more barriers to their success than their men counterparts in science, technology, engineering, and math (STEM) disciplines. While much of the research on women's experience in science has focused on their entry into or exit out of STEM fields (the "leaky pipeline"), less is known about the obstacles that women scientists face at work, due to the dearth of ethnographic work exploring gender and day-to-day experiences in the academic workplace. Using data from a qualitative study of graduate students and postdoctoral fellows in chemistry involving over 120 hours of ethnographic observation and 40 semi-structured interviews, I focus specifically on the gendered nature of authority, expertise, and impression management to investigate several of the obstacles women scientists face at work. In the first chapter, I investigate men and women graduate students' and postdocs' expectations of expertise. I argue that overall, men are more likely than their women peers to be seen as experts in chemistry. As a result, men graduate students benefit from more practice with skills that are applicable to their future careers: applying scientific knowledge to relevant questions and communicating this information to others. In the second chapter, I focus on gender and graduate student socialization. I find that the link between men, science, and academia creates a context in which men do not need to work as hard to establish their claim to scientific authority. Therefore, men are able to perform masculinity in varied and complex ways, while women, who do not embody masculinity, feel more pressure to conform to strict norms of competition that are associated with traditional masculinity. In the last chapter, I discuss the impression management strategies that men and women chemists-in-training use to navigate authority and expertise. I find that men are more likely than women to employ interactional styles that feature their expertise when in group situations, while women are more likely to minimize theirs. In contrast, while teaching, women sometimes use styles that align with masculinity rather than with femininity. Finally, men's bodies occasionally eliminate men's need for impression management in the classroom because being masculine grants them authority.

Hirshfield, Laura Ellen

440

Monitoring of Temperature Fatigue Failure Mechanism for Polyvinyl Alcohol Fiber Concrete Using Acoustic Emission Sensors  

PubMed Central

The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed. PMID:23012555

Li, Dongsheng; Cao, Hai

2012-01-01

441

Fluorescence anisotropy of cyanobacterial phycobilisomes oriented in polyvinyl alcohol (PVA) films.  

PubMed

Polarized absorption (at 296 and 85 K), fluorescence, and photoacoustic (at 296 and 85 K) spectra of antenna complexes-phycobilisomes isolated from cyanobacteriaTolypothrix tenuis andOscillatoria and embedded in isotropic and anisotropic polyvinyl alcohol films-were measured. From the sets of polarized components of emission, the anisotropy of fluorescence for the pools of differently oriented molecules was calculated. On the basis of polarized photoacoustic and emission spectra, the competition between the process of thermal deactivation of excitation and excitation energy transfer in a chain of excitation donor and acceptor chromophores of phycobilisomes is discussed. PMID:24243073

Fr?ckowiak, D; Dudkowiak, A; Zelent, B; Leblanc, R M

1991-12-01

442

The degradation in solid state of polyvinyl alcohol by gamma-irradiation  

NASA Astrophysics Data System (ADS)

The viscosity of polyvinyl alcohol (PVA) (Powder form) falls after irradiation. Gel does not occur after a dosage of above 1000 kGy. The G-values for scission under various conditions were measured. Irradiation of PVA brings about an increase in the intensity of a number of bands in the UV spectrum. It is shown that formation of unsaturated bonds and carbonyl groups occur under irradiation. The other one of radiolysis products is organic acid. After irradiation, the hydrolysis degree is unchanged.

Gongxu, Lü; Hongying, Chen; Dongyuan, Liu

1993-07-01

443

Controlled assembly of poly(vinyl pyrrolidone) fibers through an electric-field-assisted electrospinning method  

NASA Astrophysics Data System (ADS)

In this paper, we develop an effective electric-field-assisted electrospinning method for the controlled deposition of poly(vinyl pyrrolidone) fibers. The electric field distribution becomes uniform and convergent due to the introduction of a metal plate and a focusing aid into the conventional electrospinning setup. As a result, the bending instability is suppressed and the jet is restricted to moving to the collector along a straight line. Helical structure of fibers with lateral width of about 10 ?m is formed and aligned on a rotating substrate. The morphology of helical fibers can also be effectively adjusted by varying the collecting velocity.

Cui, Xiaojie; Li, Luming; Xu, Fu

2011-04-01

444

Thermal degradation of weldable poly(vinyl chloride) samples at low temperatures.  

PubMed

A study was performed to determine possible emission products during plastic welding that may be responsible for health problems. Thermal degradation of poly(vinyl chloride) samples was carried out at 170 degrees C in a thermal desorption gas chromatography (GC) injector and in a modified impinger in a GC oven, in combination with various analytical techniques, thermogravimetric analysis, capillary GC, GC-mass spectrometry, high-performance liquid chromatography and isotachophoresis. Some of the degradation products found are known to be eye irritants. PMID:3215984

Andersson, B

1988-07-22

445

Preparation and characterization of poly(vinyl alcohol)/graphene nanofibers synthesized by electrospinning  

NASA Astrophysics Data System (ADS)

We report on the synthesis and characterization of electrospun polyvinyl alcohol (PVA)/graphene nanofibers. The samples produced were characterized by Raman spectroscopy for structural and defect density analysis, scanning electron microscopy (SEM) for morphological analysis, and thermogravimetric (TGA) for thermal analysis. SEM measurements show uniform hollow PVA fibers formation and excellent graphene dispersion within the fibers, while TGA measurements show the improved thermal stability of PVA in the presence of graphene. The synthesized polymer reinforced nanofibers have potential to serve in many different applications such as thermal management, supercapacitor electrodes and biomedical materials for drug delivery.

Barzegar, Farshad; Bello, Abdulhakeem; Fabiane, Mopeli; Khamlich, Saleh; Momodu, Damilola; Taghizadeh, Fatemeh; Dangbegnon, Julien; Manyala, Ncholu

2015-02-01

446

Sliding of poly(vinyl chloride) on metals studied by Auger electron spectroscopy  

NASA Technical Reports Server (NTRS)

The sliding of polyvinyl chloride on nickel, iron and S-Monel has been studied by Auger electron spectroscopy. Polymer was not transferred to the metals, rather shear appeared to take place at the interface. The metal was progressively chlorinated as the polymer made multiple passes on the surface. The thickness of this chlorine film was the order of one atomic layer. Electron-induced desorption studies indicate that the chlorine is chemisorbed to the metal. These results are interpreted as evidence for mechanically induced and/or thermal degradation of the polymer during sliding. Degradation products of HCl and Cl2 which chemisorb to the metal are evolved near the interface.

Pepper, S. V.

1974-01-01

447

Near ultraviolet photodetector fabricated from polyvinyl-alcohol coated In2O3 nanoparticles  

NASA Astrophysics Data System (ADS)

A near ultraviolet (UV) photodetector is fabricated from colloidal In2O3 nanoparticles coated with polyvinyl-alcohol (PVA). The device exhibits lower dark current and higher responsivity compared with a photodetector fabricated from uncoated In2O3 nanoparticles. The rise and fall time of the PVA coated photodetector is about 500 s and 1600 s, respectively, one half of the uncoated device. The faster response time of the PVA enhanced photodetector is due to surface passivation which reduces the surface defects while enhancing desorption of oxygen from the nanoparticle surface, thus increasing free carrier concentration.

Shao, Dali; Qin, Liqiao; Sawyer, Shayla

2012-11-01

448

Self-written waveguide in methylene blue sensitized poly(vinyl alcohol)/acrylamide photopolymer material.  

PubMed

We report the observation of a self-written waveguide inside a bulk methylene blue sensitized poly/vinyl alcohol)/acrylamide photopolymer material. Light from a low power He-Ne laser is focused into the material, and the evolution of the beam is monitored. The refractive index of the material is modulated in the region of high intensity due to photobleaching and photopolymerization effects occurring in the material. As a result, the beam propagates through the medium without any diffraction effects. PMID:19079456

Jisha, C P; Kishore, V C; John, Beena Mary; Kuriakose, V C; Porsezian, K; Kartha, C Sudha

2008-12-10

449

Cross-linked polyvinyl alcohols and oil reservoir permeability control therewith  

SciTech Connect

This patent describes an improved method of recovering oil under steam flooding conditions from an oil-bearing subterranean formation penetrated by an injection well and a production well, in which an aqueous fluid is injected into the formation through the injection well to displace oil to the production well. The improvement comprising employing, in at least a portion of the aqueous fluid injected into the formation, a cross-linked polymer obtained by cross-linking polyvinyl alcohol with a cross-linking agent which is a mixture of a phenolic component and an aldehyde or a mixture of a naphtholic component and an aldehyde.

Hoskin, D.H.; Shu, P.

1990-01-30

450

Chemical Leucoderma Induced by Ear-ring Stoppers Made of Polyvinyl Chloride  

PubMed Central

We report a case of chemical leucoderma (CL) in a 15-year-old girl, who developed patterned depigmentation at the back of both ear lobules after contact with plastic ear-ring stoppers made of polyvinyl chloride (PVC) after continuous use for 6–7 months. Patch test with Indian standard series and cosmetic series was negative after 48 h, but she refused patch testing for extended duration as the possibility of induced depigmentation at the test site was unacceptable to her. To the best of our knowledge, this is the first report of plastic ear-ring stopper induced CL. PMID:23060712

Sharma, Reena; Singal, Archana; Verma, Prashant; Grover, Chander

2012-01-01

451

Monitoring of temperature fatigue failure mechanism for polyvinyl alcohol fiber concrete using acoustic emission sensors.  

PubMed

The applicability of acoustic emission (AE) techniques to monitor the mechanism of evolution of polyvinyl alcohol (PVA) fiber concrete damage under temperature fatigue loading is investigated. Using the temperature fatigue test, real-time AE monitoring data of PVA fiber concrete is achieved. Based on the AE signal characteristics of the whole test process and comparison of AE signals of PVA fiber concretes with different fiber contents, the damage evolution process of PVA fiber concrete is analyzed. Finally, a qualitative evaluation of the damage degree is obtained using the kurtosis index and b-value of AE characteristic parameters. The results obtained using both methods are discussed. PMID:23012555

Li, Dongsheng; Cao, Hai

2012-01-01

452

Voting for a personality: Do first impressions and self-evaluations affect voting decisions?  

PubMed Central

Participants were asked to assess their own personality (i.e. Big Five scales), the personality of politicians shown in brief silent video clips, and the probability that they would vote for these politicians. Response surface analyses (RSA) revealed noteworthy effects of self-ratings and observer-ratings of openness, agreeableness, and emotional stability on voting probability. Furthermore, the participants perceived themselves as being more open, more agreeable, more emotionally stable, and more extraverted than the average politician. The study supports previous findings that first impressions affect decision making on important issues. Results also indicate that when only nonverbal information is available people prefer political candidates they perceive as having personality traits they value in themselves. PMID:25089064

Koppensteiner, Markus; Stephan, Pia

2014-01-01

453

Lifting the curtain on the Wizard of Oz: biased voice-based impressions of speaker size.  

PubMed

The consistent, but often wrong, impressions people form of the size of unseen speakers are not random but rather point to a consistent misattribution bias, one that the advertising, broadcasting, and entertainment industries also routinely exploit. The authors report 3 experiments examining the perceptual basis of this bias. The results indicate that, under controlled experimental conditions, listeners can make relative size distinctions between male speakers using reliable cues carried in voice formant frequencies (resonant frequencies, or timbre) but that this ability can be perturbed by discordant voice fundamental frequency (F-sub-0, or pitch) differences between speakers. The authors introduce 3 accounts for the perceptual pull that voice F-sub-0 can exert on our routine (mis)attributions of speaker size and consider the role that voice F-sub-0 plays in additional voice-based attributions that may or may not be reliable but that have clear size connotations. PMID:17924818

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

2007-10-01

454

Comparative analysis of dental enamel polyvinylsiloxane impression and polyurethane casting methods for SEM research.  

PubMed

Dental casting is a very common procedure for making high-quality replicas of paleo-anthropological remains. Replicas are frequently used, instead of original remains, to study both fossil and extant Primate teeth in morphological and metrical analyses. Several commercial products can be used in molds. This study analyzed SEM image resolution and enamel surface feature definition of tooth molds at various magnification levels and obtained, with both Coltène and 3M low-viscosity body polyvinylsiloxane impression, materials and polyurethane casts. Results, through comparison with the original teeth, show that both the negative molds and the positive casts are highly reliable in replicating enamel surfaces. However, positive cast quality is optimal for SEM observation only till the fourth consecutive replica from the original mold, especially at high SEM magnification levels. PMID:16586485

Galbany, Jordi; Estebaranz, Ferran; Martínez, Laura M; Romero, Alejandro; De Juan, Joaquín; Turbón, Daniel; Pérez-Pérez, Alejandro

2006-04-01

455

Students' and Instructor's Impressions of Ill-structured Capstone Projects in an Advanced Electronics Lab  

NSDL National Science Digital Library

During spring 2010 six students enrolled in an advanced electronics lab worked in pairs on ill-structured capstone projects. They designed electronic circuitry to automate experiments that were completed in a previous advanced physics lab. Some ill-structured features of these capstone projects included open-ended goals, limited guidance from the instructor and the possibility of multiple solution paths. Semi-structured interviews were conducted with both the students and the instructor of the class, before and after the students worked on these ill-structured capstone projects to gauge the participants' expectations of the projects before they began and their views about these projects after they were completed. We report on the pre- and post-project impressions of the students and instructors regarding this ill-structured learning experience.

Juma, Nasser M.; Gire, Elizabeth; Corwin, Kristan; Washburn, Brian; Rebello, N. S.

2013-05-08

456

The slope parameter approach to marine cathodic protection design and its application to impressed current systems  

SciTech Connect

The recently developed slope parameter approach to design of galvanic anode cathodic protection (cp) systems for marine structures constitutes an advancement in this technology compared to current practice, primarily because the former is first principles based and the latter is an empirical algorithm. In this paper, the slope parameter approach is reviewed; and related applications for which it can be utilized, including (1) design of new and retrofit cp systems, (2) evaluation of potential survey data, and (3) cp system design for complex geometries, are mentioned. The design current density is identified as the single remaining parameter for which values must be projected solely by experience or experimentation. In addition, the slope parameter approach is applied to the results of impressed current cp experiments, and it is shown how parameters for this can be interrelated with those of galvanic anode cp. Advantages of this capability are identified and discussed.

Hartt, W.H.

1999-07-01

457

Effect of Storage Time of Extended-Pour and Conventional Alginate Impressions on Dimensional Accuracy of Casts  

PubMed Central

Objectives: Some manufacturers claim to have produced new irreversible hydro-colloids that are able to maintain their dimensional stability during storage. The present study evaluated the effect of storage time on dimensional stability of three alginates: Hydrogum 5, Tropicalgin and Alginoplast. Materials and Methods: In this experimental in-vitro trial, a total of 90 alginate impressions were made from a Dentoform model using Hydrogum 5, Tropicalgin and Alginoplast alginates. The impressions were stored in a sealed plastic bag without a damp paper towel for 0, 24, 48, 72 and 120 hours and then poured with type III dental stone. Cross-arch (facial of 6 to facial of 6 on the opposite side) and antero-posterior (distal of right first molar to the ipsilateral central incisor) measurements were made with a digital caliper on the casts. Data were analyzed by two-way and one-way ANOVA and Tukey’s post-hoc test (P<0.05). Results: Alginate type and the pouring time significantly affected the dimensional stability of alginate impressions (both Ps<0.001). Pouring of Hydrogum 5 impressions can be delayed for up to 120 hours without significant dimensional changes. Alginoplast impressions may be poured after 72 hours, but Tropicalgin should be poured immediately and the storage time should not be more than 24 hours. Conclusion: Immediate pouring of alginate impressions provides the highest accuracy in reproducing the teeth and adjacent tissues; however, this study demonstrated that pouring may be delayed for up to five days using extended-pour (Hydrogum 5) alginates.

Rohanian, Ahmad; Ommati Shabestari, Ghasem; Zeighami, Somayeh; Samadi, Mohammad Javad; Shamshiri, Ahmad Reza

2014-01-01

458

Poly(vinyl alcohol) (PVA) is a polymer of great interest because of its many desirable characteristics specifically for various pharmaceutical and biomedical applications. The  

E-print Network

Poly(vinyl alcohol) (PVA) is a polymer of great interest because of its many desirable development of freeze/thawed PVA hydrogels are addressed. Keywords. Poly(vinyl alcohol), Hydrogels, Freezing(vinyl alcohol) (PVA) . . . . . . 38 2 Synthesis and Properties of PVA Hydrogels. . . . . . . . . . . . . 39 3

Peppas, Nicholas A.

459

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

NASA Astrophysics Data System (ADS)

A gas-liquid phase sol-gel process was proposed to reinforce a poly(dimethyl siloxane) (PDMS) mold with high aspect ratio microstructures (HARMs) for micromolding. Unlike the conventional sol-gel process or in situ precipitation of silicate nanoparticles (SiO2) inside the PDMS network, the vapor of water and aminomethyl propanol-95 permeated through the PDMS which was pre-soaked with tetraethoxy silane (TEOS), leading to the occurrence of hydrolysis and condensation and reinforcement of the PDMS. The reinforced PDMS mold with HARMs was used for micromolding, and high replication accuracy was achieved. The proposed technique not only prevents the surface of microstructures on the mold from potential agglomeration of particles but also allows for the repetitive usage of the silicon mother mold without damage.

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

2009-04-01

460

Biaxial order and a rotation of the minor director in the nematic phase of an organo-siloxane tetrapode by the electric field  

NASA Astrophysics Data System (ADS)

Biaxiality in the nematic phase for a liquid crystalline tetrapode made up of organo-siloxanes mesogens is investigated using polarized infrared spectroscopy. An ordering of the minor director for the homeotropically aligned sample is found to depend on the amplitude of the in-plane electric field. On increasing the in-plane electric field, the minor director, lying initially along the rubbing direction, rotates to the direction of the applied field. The scalar order parameters of the second rank tensor are found to depend significantly on the strength of the electric field. A most significant increase is found in the nematic order parameter and in the parameter that characterizes the phase biaxiality.

Merkel, K.; Nagaraj, M.; Kocot, A.; Kohlmeier, A.; Mehl, G. H.; Vij, J. K.

2012-03-01

461

Copolycondensation of Functional Silanes and Siloxanes in Solution Using tris(pentafluorophenyl)borane as a Catalyst in a View to Generate Hybrid Silicones  

NASA Astrophysics Data System (ADS)

This paper proposes new ways of preparation of hybrid silicones, i.e. an alternated multiblock sequence of silicone and alkyl spacers, via a polycondensation process catalyzed by the tris(pentafluorophenyl)borane, a water-tolerant Lewis acid, between methoxy and hydrogeno functionalized silanes and siloxanes at room temperature and in the open air. The protocol was first developed with model molecules which led to polydimethylsiloxane (PDMS) chains, in order to seize the best experimental conditions. Several factors were studied such as the contents of each reactants, the nature of the solvent or the rate of addition. The best conditions were then adapted to the synthesis of hybrid silicones, condensing alkylated oligocarbosiloxanes with methoxy or hydrogeno chain-ends and complementary small molecules. A systematic limitation in final molar masses of hybrid silicones was observed and explained by the formation of macrocycles, which cannot redistribute or condense further while formed.

Longuet, Claire; Ganachaud, François

462

Siloxane containing addition polyimides  

NASA Technical Reports Server (NTRS)

Addition polyimide oligomers have been synthesized from bis(gamma-aminopropyl) tetramethyldisiloxane and 3, 3', 4, 4'-benzophenonetetracarboxylic dianhydride using a variety of latent crosslinking groups as endcappers. The prepolymers were isolated and characterized for solubility (in amide, chlorinated and ether solvents), melt flow and cure properties. The most promising systems, maleimide and acetylene terminated prepolymers, were selected for detailed study. Graphite cloth reinforced composites were prepared and properties compared with those of graphite/Kerimid 601, a commercially available bismaleimide. Mixtures of the maleimide terminated system with Kerimid 601, in varying proportions, were also studied.

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

1984-01-01

463

METAL COMPLEXING SILOXANE POLYMERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Novel silicone polymers containing pendant phosphonate groups have been synthesized. A new silicone monomer, (CH3O)2CH3Si(CH2)3P=O(OCH2CH3)2 has been copolymerized with dimethyldimethoxysilane to form polymers capable of binding metal salts. The viscous liquids can complex a variety of metals, inc...

464

A quantitative histochemical study of 5?-nucleotidase activity in rat liver using the lead salt method and polyvinyl alcohol  

Microsoft Academic Search

Summary  5-Nucleotidase (EC 3.1.3.5) activity was demonstrated in cryostat sections of rat liver using the Wachstein—Meisel medium and polyvinyl alcohol as tissue stabilizer. Optimum activity was obtained using an incubation medium containing 5mm AMP, 10mm magnesium chloride, 7.2mm lead nitrate, 0.1m Tris—maleate buffer, pH 7.2, and 17% (w\\/v) polyvinyl alcohol (Sigma, type III). The activity was localized at the bile canalicular

Wilma M. Frederiks; Frans Marx

1988-01-01

465

Deep ultraviolet photoresist based on tungsten polyoxometalates and poly(vinyl alcohol) for bilayer photolithography  

SciTech Connect

In this paper a negative tone deep ultraviolet resist, a mixture of phosphotungstic acid and poly(vinyl alcohol) is described. This resist has {lt}100 mJ cm{sup {minus}2} sensitivity and resolves {le}0.3 {mu}m features. Even though the photochemistry involves chemical amplification, the exposed patterns are stable and the process tolerates hours between the exposure and the post-bake steps. The resist is spun from an aqueous solutio, and its wet processing is also aqueous. This resist is used in a bilayer scheme, where advantage is taken of both the resistance of the tungsten oxide to oxygen plasmas and its easy stripping in fluorine-containing plasmas. Because poly(vinyl alcohol) is intrisincally a wetting agent, pinhole-free resist films of {approximately}1000 {Angstrom} thickness can be spun. These thin coatings provide sufficient oxygen plasma etch resistance to allow patterning of a thick 1.5 {mu}m novolac planarizing layer underneath the resist.

Carls, J.C.; Argitis, P.; Heller, A. (Dept. of Chemical Engineering, Univ. of Texas at Austin, Austin, TX (US))

1992-03-01

466

Elution behavior of oligomers on a polyvinyl alcohol gel column with chloroform, methanol, and their mixtures  

SciTech Connect

Elution phenomena of size exclusion chromatography (SEC) plus superimposed adsorption effects for oligostyrenes, epoxy resins, methylated melamine-formaldehyde resin prepolymers, p-cresol-formaldehyde resin prepolymers, and phenol-formaldehyde resin prepolymers were investigated. SEC and superimposed adsorption effects could be elucidated from a concept of solubility parameter. Minimum retention volumes of these obligomers were obtained with the mobile phases of chloroform/methanol, 80/20 or 60/40 (v/v), and separation was expected to be mostly performed by SEC. The solubility parameter of polyvinyl alcohol gels was estimated to be between 21 and 23 from the above results. Elution for normal phase chromatography was in the order of increasing molecular weight and that for reversed-phase chromatography was in the order of decreasing molecular weight. These are reversed phenomena to those for low-molecular weigh compounds. Solubility of sample solutes to mobile phase must be considered. Methanol mobile phase-polyvinyl alcohol gel system might be exception.

Mori, S. (Dept. of Industrial Chemistry, Faculty of Engineering, Mie Univ., Tsu, Mie 514 (JP))

1988-01-01

467

Vibrational and configurational heat capacity of poly(vinyl acetate) from dynamic measurements.  

PubMed

The complex heat capacity C(p) (*) of poly(vinyl acetate) has been measured at 20.95 mrads modulation frequency during the cooling as well as on heating at 24, 8, and 2 Kh and during cooling at 0.5 Kh. The study is complemented with (the rate-dependent) C(p,app) measured during cooling and heating at 60, 24, and 8 Kh. At low temperatures, the real component of C(p) (*) yields the unrelaxed C(p) or C(p,vib), the vibrational part of C(p). It is found to be indistinguishable from C(p,glass) and lies on a line extrapolated to its equilibrium melt's temperature. At T near T(g),DeltaC(p)(=C(p,melt)-C(p,glass)) shows no detectable contribution from C(p,vib). The finding conflicts with a modified entropy theory calculation [E. A. DiMarzio and F. Dowell, J. Appl. Phys. 50, 6061 (1979)], which had predicted that approximately 27% of DeltaC(p) of poly(vinyl acetate) at T near T(g) is vibrational in origin and the remainder configurational. At T

Tombari, E; Ziparo, C; Salvetti, G; Johari, G P

2007-07-01

468

"Walking into a Dark Room"--The Initial Impressions of Learner-Educators in Further Education and Training  

ERIC Educational Resources Information Center

This paper takes as its focus the initial impressions of education and the role of the educator among those entering the "profession" of "FE educator". The research is carried out with those currently working as educators undertaking recognised teaching qualifications through part-time, in-service training at either C&G Stage 1 & 2 Combined or…

Spenceley, Lydia

2007-01-01

469

Calculating Clinically Significant Change: Applications of the Clinical Global Impressions (CGI) Scale to Evaluate Client Outcomes in Private Practice  

ERIC Educational Resources Information Center

The Clinical Global Impressions (CGI) scale is a therapist-rated measure of client outcome that has been widely used within the research literature. The current study aimed to develop reliable and clinically significant change indices for the CGI, and to demonstrate its application in private psychological practice. Following the guidelines…

Kelly, Peter James

2010-01-01

470

First Impressions of an Educational Website: The Relationship between Student Attributes and Visual Preferences for the Digital Learning Environment  

ERIC Educational Resources Information Center

The present study examined students' first impressions of different aesthetic treatments for the same web-based lesson about the experiences of British soldiers during World War I as expressed through examples of trench poetry. Holding site content and functionality constant, the interface design's visual presentation was manipulated along two…

Manning, Flori H.; Lawless, Kimberly A.

2011-01-01

471

One Starfish at a Time: Using Fundamentals in Sociology to Rethink Impressions about People Living with HIV/AIDS  

ERIC Educational Resources Information Center

The purpose of this article is to document how a course in the fundamentals of sociology encouraged students to rethink negative impressions about people with AIDS. Multimethod, active learning processes were utilized to introduce the sociological imagination, critical thinking, and theory and methods in sociology. The intent was to apply basic…

Moremen, Robin D.

2010-01-01

472

An Exploratory Investigation Examining the Cues that Students Use to Form Initial Impressions and Expectancies of Lecturers  

ERIC Educational Resources Information Center

The aim of this study was to examine the informational cues that students perceive to be influential when developing initial impressions and expectancies of a lecturer. Undergraduate university students (n = 452) were required to rate the extent to which 30 informational cues (e.g. gender, qualifications) influence their initial perceptions of a…

Birch, Phil David John; Batten, John; Manley, Andrew John; Smith, Matthew Jeffery

2012-01-01

473

Personal impressions of Sigmund Freud and his work, with special reference to his recent lectures at Clark University  

Microsoft Academic Search

Discusses authors' personal impressions about Sigmund Freud and his work, based on Freuds' lecture at Clark University. Presents a brief history of Freud's investigations and opinions. The doctrines and methods of Freud have been acknowledged as being full of interest as they throw light upon the mode in which the mind works, independent of the particular nature of the emotions

James J. Putnam

1909-01-01

474

A Longitudinal Study of Impression Management Strategies and Leadership Emergence: The Moderating Roles of Gender and Virtualness  

ERIC Educational Resources Information Center

This study used a longitudinal study spanning a twelve-week time period and involving 165 undergraduate students to examine the combined impact of gender and impression management strategies on leader emergence by members relying on low versus high virtualness. The subjects were formed into 44 self-managed work groups and charged with completing…

Lim, Yong-Kwan

2011-01-01

475

Substance Use in Adolescent Psychiatric Outpatients: Self-Report, Health Care Providers' Clinical Impressions, and Urine Screening  

ERIC Educational Resources Information Center

Purpose: To determine the prevalence of substance use among adolescent psychiatric outpatients using a variety of data sources. Method: Using a questionnaire, 3-month prevalence of substance use data were obtained from 50 adolescents and their health care providers. Adolescents' self-reports and providers' clinical impressions were…

Holzer, Laurent; Pihet, Sandrine; Passini, Christina Moses; Feijo, Isabelle; Camus, Didier; Eap, Chin

2014-01-01

476

Trainees' Perceived Knowledge Gain Unrelated to the Training Domain: The Joint Action of Impression Management and Motives  

ERIC Educational Resources Information Center

Trainees' knowledge gains represent an important outcome in human resource development. In this research, we tested a model examining the joint influence of social desirability (impression management, self-deception) and motives (need for power, need for approval) on trainees' self-reported knowledge gain. We conducted a study with…

Chiaburu, Dan S.; Huang, Jason L.; Hutchins, Holly M.; Gardner, Richard G.

2014-01-01

477

A pilot study to determine the effects of skin contact on two commonly used dental impression materials.  

PubMed

Impression materials used in the analysis of bite marks are required to maintain their stability and integrity for extended periods. It has been observed that certain impressions taken of skin lose their properties with time, becoming sticky and unusable as evidence. The objective of this study was to investigate the onset of "stickiness" in two commonly used dental impression materials when brought into contact with skin. The two materials tested were Impregum and President. They were syringed into glass rings positioned on the upper arms of 28 volunteers. Changes in stickiness were monitored over a four-month period using a tensile testing machine. A metal plunger was lowered onto the impression material and then retracted measuring the adhesive force of the material to the lower surface of the plunger. Over the research period 17 of the 28 rings of Impregum became sticky and changed colour from purple to turquoise. The remaining 11 Impregum samples, all the President samples and all control samples remained unchanged over the 120 day period. The results of this study show that certain factors present in or on skin are responsible for the loss of surface integrity of Impregum. The factors responsible for these changes have not been established. PMID:17175838

Steyn, N; Botha, S J; Brand, P D; Bernitz, H

2006-12-01

478

Verification jig for implant-supported prostheses: A comparison of standard impressions with verification jigs made of different materials  

Microsoft Academic Search

Statement of Problem. Implant verification jigs are routinely used during the fabrication of implant-supported prostheses. The dimensional accuracy of these jigs is unknown. Purpose. The purposes of this study were to (1) compare the dimensional accuracy of verification jigs with that of conventional impression procedures and (2) measure the dimensional accuracy of 3 resin materials used to fabricate verification jigs.

Jorge E. De La Cruz; Paul D. Funkenbusch; Carlo Ercoli; Mark E. Moss; Gerald N. Graser; Ross H. Tallents

2002-01-01

479

Using Dynamic Geometry Software GeoGebra in Developing Countries: A Case Study of Impressions of Mathematics Teachers in Nepal  

ERIC Educational Resources Information Center

This article describes a professional development initiative for fifteen mathematics teachers in the use of dynamic geometry software GeoGebra. A four-day introductory workshop was given