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1

Effect of poly(vinyl acetate) (PVAc) on thermal behavior and mechanical properties of poly(3-hydroxybutyrate)\\/poly(propylene carbonate) (PHB\\/PPC) blends  

Microsoft Academic Search

To assess the compatibility of blends of synthetic poly(propylene carbonate) (PPC), with a natural bacterial poly(3-hydroxybutyrate) (PHB), a simple casting procedure of blend was used. poly(3-hydroxybutyrate)\\/poly(propylene carbonate) blends are found to be incompatible according to DSC and DMA analysis. In order to improve the compatibility and mechanical properties of PHB\\/PPC blends, poly(vinyl acetate) (PVAc) was added as a compatibilizer. The

Xiuyan Wang; Shuwen Peng; Lisong Dong

2005-01-01

2

Crosslinkable poly(vinyl acetate) emulsions for wood adhesive  

Microsoft Academic Search

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

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

2011-01-01

3

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

EPA Science Inventory

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

4

Cosolvent gel-like materials from partially hydrolyzed poly(vinyl acetate)s and borax.  

PubMed

A gel-like, high-viscosity polymeric dispersion (HVPD) based on cross-linked borate, partially hydrolyzed poly(vinyl acetate) (xPVAc, where x is the percent hydrolysis) is described. Unlike hydro-HVPDs prepared from poly(vinyl alcohol) (PVA) and borate, the liquid portion of these materials can be composed of up to 75% of an organic cosolvent because of the influence of residual acetate groups on the polymer backbone. The effects of the degree of hydrolysis, molecular weight, polymer and cross-linker concentrations, and type and amount of organic cosolvent on the rheological and structural properties of the materials are investigated. The stability of the systems is explored through rheological and melting-range studies. (11)B NMR and small-angle neutron scattering (SANS) are used to probe the structure of the dispersions. The addition of an organic liquid to the xPVAc-borate HVPDs results in a drastic increase in the number of cross-linked borate species as well as the agglomeration of the polymer into bundles. These effects result in an increase in the relaxation time and thermal stability of the networks. The ability to make xPVAc-borate HVPDs with very large amounts of and rather different organic liquids, with very different rheological properties that can be controlled easily, opens new possibilities for applications of PVAc-based dispersions. PMID:21848256

Angelova, Lora V; Terech, Pierre; Natali, Irene; Dei, Luigi; Carretti, Emiliano; Weiss, Richard G

2011-09-20

5

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

Microsoft Academic Search

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

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

2000-01-01

6

Oral 4-week and 13-week toxicity studies of polyvinyl acetate vinyl laurate copolymer in rats.  

PubMed

Polyvinyl acetate vinyl laurate copolymer (PVAcVL) is a useful component of gum base for chewing gum production. The safety of PVAcVL was examined in a 4-week and a 13-week oral toxicity study in rats. Finely powdered PVAcVL was administered with the diet at levels of 1.25%, 2.0% and 5% in the 4-week study and 1.25%, 2.5% and 5% in the 13-week study. There were no treatment related effects on mortality, bodyweight gains feed efficiency, ophthalmoscopic findings, hematological and clinical chemical parameters, neurobehavioral observations as well as gross and histopathological changes of standard organs and tissues. The highest dose tested in the 13-week study (3783 and 4396mg/kgbw/d for males and females, respectively) proved to be a NOAEL. PMID:24932800

Messinger, Horst; Bär, Albert

2014-10-01

7

Photochemical degradation study of polyvinyl acetate paints used in artworks by Py-GC/MS  

PubMed Central

Photochemical degradation of commercial polyvinyl acetate (PVAc) homopolymer and PVAc paints mixed with burnt umber, cobalt blue, cadmium red dark, nickel azo yellow and titanium white commonly used for artworks were studied by pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Py–GC/MS with single-shot technique was used for the characterization of the thermal degradation of PVAc at different temperatures, while the double-shot technique of Py–GC/MS was used to reveal the differences in the specimens before and after UV ageing, including the changes of detectable amounts of deacetylation product – acetic acid and plasticizers such as diethyl phthalate (DEP). Furthermore, the relative concentration of the pyrolysis products of the paint samples could be measured and compared in the second step of the double-shot Py–GC/MS, which are highly dependent on the presence of pigments and the ageing status of PVAc paints. PMID:23024446

Wei, Shuya; Pintus, Valentina; Schreiner, Manfred

2012-01-01

8

Method development for compositional analysis of low molecular weight poly(vinyl acetate) by matrix-assisted/laser desorption-mass spectrometry and its application to analysis of chewing gum.  

PubMed

The influence of the sample preparation parameters (the choice of the solvent and of the matrix:analyte ratio) was investigated and optimal conditions were established for MALDI mass spectrometry analysis of the pristine low molecular weight polyvinyl acetate (PVAc). It was demonstrated that comparison of polymer's and solvent's Hansen solubility parameters could be used as a guide when choosing the solvent for MALDI sample preparation. The highest intensity PVAc signals were obtained when ethyl acetate was used as a solvent along with the lowest matrix-analyte ratio (2,5-dihydroxybenzoic acid was used as a matrix in all experiments). The structure of the PVAc was established with high accuracy using the matrix-assisted laser desorption/ionization-Fourier transform mass spectrometry (MALDI-FTMS) analysis. It was demonstrated that PVAc undergoes unimolecular decomposition by losing acetic acid molecules from its backbone under the conditions of FTMS measurements. Number and weight average molecular weights as well as polydispersity indices were determined with both MALDI-TOF and MALDI-FTMS methods. The sample preparation protocol developed was applied to the analysis of a chewing gum and the molecular weight and structure of the polyvinyl acetate present in the sample were established. Thus, it was shown that optimized MALDI mass spectrometry could be used successfully for characterization of polyvinyl acetate in commercially available chewing gum. PMID:24745742

Tisdale, Evgenia; Wilkins, Charles

2014-04-11

9

Temperature divergence of the dynamics of a poly(vinyl acetate) glass: dielectric vs. mechanical behaviors.  

PubMed

The dynamics of glass forming liquids as the glass transition temperature (T(g)) is traversed has become of special interest because of the continuing question as to whether or not the dynamics diverge towards an ideal glass transition/Kauzmann temperature or if the apparent Vogel-Fulcher-Tammann (VFT) divergence is lost as one goes below the conventional T(g) but remains in equilibrium. Here we examine the response of a poly(vinyl acetate) PVAc polymer glass-former using both dielectric and mechanical methods in the vicinity of T(g). Isothermal measurements were performed to study the aging behavior of the PVAc and to assure that the equilibrium state was achieved for temperatures as much as 16 K below the calorimetric T(g). Surprisingly, we found that the mechanical response took much longer to age into its equilibrium than did the dielectric response. Also, the temperature dependence of the time-temperature shift factors obtained from the two methods is different and the dielectric response shows a turnover to an apparent Arrhenius behavior rather than a continuation of the VFT extrapolated divergence at the lowest temperatures tested. PMID:22519344

Zhao, Jing; McKenna, Gregory B

2012-04-21

10

Polyvinyl acetate-based film coatings.  

PubMed

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

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

2013-12-01

11

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

PubMed

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

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

2010-03-01

12

Structural and mechanical properties of "peelable" organoaqueous dispersions with partially hydrolyzed poly(vinyl acetate)-borate networks: applications to cleaning painted surfaces.  

PubMed

The preparation and structural characterization of a family of viscoelastic dispersions of borate cross-linked, 80% hydrolyzed poly(vinyl acetate) (80PVAc) in aqueous-organic liquids are presented. Correlations between mechanical properties (from rheological measurements) and the degree and nature of cross-linking (from (11)B NMR spectroscopy) are reported, and the results are used to assess their potential as low-impact cleaning agents for the surfaces of paintings. Because the dispersions can be prepared at room temperature by simple procedures from readily available materials and can contain up to 50% (w/w) of an organic liquid, they offer important advantages over previously described cleaning agents that are based on fully hydrolyzed PVAc (i.e., poly(vinyl alcohol). The mechanical properties of the various aqueous-organic dispersions, as determined quantitatively by rheological investigations and qualitatively by their ease of removal from a solid surface (i.e., the so-called "peel-off" ability) have been tuned systematically by varying the amount of organic liquid, its structure, and the concentrations of borax and 80PVAc. The (11)B NMR studies demonstrate that the concentration of borate ions actively participating in cross-linking increases significantly with the amount of organic liquid in the mixture. The degree of cross-linking remains constant when the 80PVAc and borax concentrations are varied, as long as their ratios are kept constant. Some of the 80PVAc-borax dispersions have been tested successfully as cleaning agents on the surface of a 16th-17th century oil-on-wood painting by Lodovico Cardi, "Il Cigoli", that was covered by a brown patina and on the surface of a Renaissance wall painting by Vecchietta in Santa Maria della Scala, Siena, Italy, that had a degraded polyacrylate coating from a previous conservation treatment. PMID:21749078

Natali, Irene; Carretti, Emiliano; Angelova, Lora; Baglioni, Piero; Weiss, Richard G; Dei, Luigi

2011-11-01

13

Synthesis of Modified Poly(vinyl acetate) Adhesives  

Microsoft Academic Search

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

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

2010-01-01

14

Conformational features of poly(1,1-dihydroperfluorooctyl acrylate) and poly(vinyl acetate) diblock oligomers in supercritical carbon dioxide  

NASA Astrophysics Data System (ADS)

We report detailed molecular dynamics calculations of single chain diblocks of poly(1,1- dihydroperfluorooctyl acrylate) (PFOA) and poly(vinyl acetate) (PVAc) in supercritical carbon dioxide, SCCO2. At the critical micelle concentration, this system exhibits self-assembly into micellar structures due to the solvent specific selectivity of the blocks. Although the intermolecular factors determining micelle formation are well studied for this system, the intramolecular single chain conformational features of the molecules have not yet been investigated in the literature. The specific aim of the present work is to study the conformational properties of the single diblock chains in supercritical carbon dioxide at 65 °C, and at four different pressures by molecular dynamics simulations. Fluctuations in the shapes of the PVAc and PFOA blocks are observed to be strongly dependent on pressure. The rate of approach of an initially rodlike chain to its equilibrium conformational space is likewise found to depend strongly on pressure. Calculations of the radial distribution function for the solvent molecules around the chain show that a solvation shell is formed around the polymer. Important correlations between the results of single chain calculations and micelle behavior are observed and discussed.

Baysal, Canan; Erman, Burak; Chu, Benjamin

2001-03-01

15

Physicochemical characterization of partially hydrolyzed poly(vinyl acetate)-borate aqueous dispersions.  

PubMed

The dynamic and structural properties of Highly Viscous Polymeric Dispersions (HVPDs), constituted of polyvinyl alcohol obtained from the 75% hydrolysis (75PVA) of polyvinlyl acetate (PVAc) cross-linked with borate ions, were studied as a function of the 75PVA concentration at a constant ratio between the OH groups and the borate ions (OH/B(OH)4(-)). The threshold 75PVA concentration C* necessary for the formation of the three-dimensional network was determined by flow rheology. The oscillating rheology measurements were performed in the linear viscoelastic region; the relaxation spectra calculated from the frequency sweep curves showed only one peak whose width increased upon increasing the 75PVA concentration due to the broadening of the relaxation modes. The dependence of the mean relaxation time ?H upon the concentration of 75PVA followed a power law expression (?H ? C(x) with x = 1.9) indicating that ?H referred to a sticky reptation mechanism and that water was a good solvent for 75PVA as confirmed also by small angle X-rays scattering (SAXS) investigation. The HVPDs were used for the removal of grime layers from the surface of Carlo Carrà (1881-1966) paints decorating the walls of the Palazzo di Giustizia in Milan, Italy. PMID:24818671

Carretti, E; Matarrese, C; Fratini, E; Baglioni, P; Dei, L

2014-07-01

16

Spectroscopic and thermal studies of PS/PVAc blends  

NASA Astrophysics Data System (ADS)

Polystyrene and polyvinyl acetate (PS/PVAc) films were blended with different contents using casting method. The effect of PS content on PVAc blends was investigated by Fourier transform infrared (FT-IR), X-ray diffraction (XRD), Ultra violet and visible studies (UV/VIS), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Significant changes in FT-IR, XRD and DSC analysis are observed which reveals an interactions between the two polymers and PS/PVAc blends had good or certain miscibility. XRD scans show some changes in the intensity and the height of the amorphous halos with increased PS. UV/VIS analysis revealed that the optical band gap decreases with increasing content of PS from 5 to 4.11 eV. A single glass transition temperature for each blend was observed, this DSC results supported that the miscibility existed in the blend. The apparent activation energy (E) of the blends was evaluated using TGA analysis. The value of E was increased with the increase of PS content.

Elashmawi, I. S.; Hakeem, N. A.; Abdelrazek, E. M.

2008-10-01

17

Phonon transport in an initially twisted polyvinyl acetate nanofiber  

NASA Astrophysics Data System (ADS)

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

Liangruksa, Monrudee; Puri, Ishwar K.

2013-05-01

18

Composite poly(vinyl alcohol)/poly(vinyl acetate) electrospun nanofibrous mats as a novel wound dressing matrix for controlled release of drugs.  

PubMed

The aim of this study was to develop novel biomedicated nanofiber electrospun mats for controlled drug release, especially drug release directly to an injury site to accelerate wound healing. Nanofibers of poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), and a 50:50 composite blend, loaded with ciprofloxacin HCl (CipHCl), were successfully prepared by an electrospinning technique for the first time. The morphology and average diameter of the electrospun nanofibers were investigated by scanning electron microscopy. X-ray diffraction studies indicated an amorphous distribution of the drug inside the nanofiber blend. Introducing the drug into polymeric solutions significantly decreased solution viscosities as well as nanofiber diameter. In vitro drug release evaluations showed that both the kind of polymer and the amount of drug loaded greatly affected the degree of swelling, weight loss, and initial burst and rate of drug release. Blending PVA and PVAc exhibited a useful and convenient method for electrospinning in order to control the rate and period of drug release in wound healing applications. Also, the thickness of the blend nanofiber mats strongly influenced the initial release and rate of drug release. PMID:21720511

Jannesari, Marziyeh; Varshosaz, Jaleh; Morshed, Mohammad; Zamani, Maedeh

2011-01-01

19

Composite poly(vinyl alcohol)/poly(vinyl acetate) electrospun nanofibrous mats as a novel wound dressing matrix for controlled release of drugs  

PubMed Central

The aim of this study was to develop novel biomedicated nanofiber electrospun mats for controlled drug release, especially drug release directly to an injury site to accelerate wound healing. Nanofibers of poly(vinyl alcohol) (PVA), poly(vinyl acetate) (PVAc), and a 50:50 composite blend, loaded with ciprofloxacin HCl (CipHCl), were successfully prepared by an electrospinning technique for the first time. The morphology and average diameter of the electrospun nanofibers were investigated by scanning electron microscopy. X-ray diffraction studies indicated an amorphous distribution of the drug inside the nanofiber blend. Introducing the drug into polymeric solutions significantly decreased solution viscosities as well as nanofiber diameter. In vitro drug release evaluations showed that both the kind of polymer and the amount of drug loaded greatly affected the degree of swelling, weight loss, and initial burst and rate of drug release. Blending PVA and PVAc exhibited a useful and convenient method for electrospinning in order to control the rate and period of drug release in wound healing applications. Also, the thickness of the blend nanofiber mats strongly influenced the initial release and rate of drug release. PMID:21720511

Jannesari, Marziyeh; Varshosaz, Jaleh; Morshed, Mohammad; Zamani, Maedeh

2011-01-01

20

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

Microsoft Academic Search

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

Alireza Kaboorani; Bernard Riedl

2011-01-01

21

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

22

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

23

Biomedical applications of stereoregular poly(vinyl alcohol) micro- and nanoparticles  

NASA Astrophysics Data System (ADS)

Syndiotactic poly(vinyl alcohol) (PVA)/poly(vinyl pivalate/vinyl acetate) (P(VPi/VAc)) and atactic PVA/PVAc micro- and nanoparticles with skin/core structure have been prepared by heterogeneous saponification of P(VPi/VAc) and PVAc micro- and nanoparticles. Especially, to prepare P(VPi/VAc) and PVAc microparticles having various particle sizes and uniform particle size distribution, vinyl pivalate (VPi)/vinyl acetate (VAc) and VAc were suspension-polymerized using a low-temperature initiator, 2,2"-azobis(2,4-dimethylvaleronitrile). P(VPi/VAc) particles are promising precursor of stereoregular PVA embolic materials which can be introduced through catheters in the management of gastrointestinal bleeders, arteriovenous malformations, hemangiomas, and traumatic rupture of blood vessels. Monodisperse and/or nearly monodisperse P(VPi/VAc) and PVAc microparticles with various particle diameters were obtained by controlling suspension polymerization conditions. Monodisperse P(VPi/VAc) and PVAc microparticles having various particle sizes were partially saponified in the heterogeneous system. PVA/P(VPi/VAc) and PVA/PVAc microparticles having various tacticity and degree of saponification were produced by controlling various polymerization and saponification conditions. The coating of stereoregular PVA micro- and nanoparticles for drug release experiments was conducted with the strepo-avidin-alkaline phosphatase conjugate in variable conditions of pH value, coating buffer, and reaction temperature. Protein-coated syndiotactic PVA micro- and nanoparticles, which does not crosslinking, were more superior to controllability of drug release, durability, and dimensional stability to water and blood than atactic one.

Lyoo, Won Seok; Kim, Joon Ho; Kim, Sam Soo; Ghim, Han Do

2002-11-01

24

Preparation and study of poly(vinyl acetate) and poly(styrene) nanosized latex with indometacin.  

PubMed

During the last decade the number of investigations on the preparation and application of more effective drug release systems on the basis of nanocarriers from biocompatible and biodegradable polymers are considerably increasing. This is notably in force for practically water insoluble drugs to be applied in liquid forms (eye solutions for an example). The aim of the work presented was the preparation of model poly(vinyl acetate) and poly(styrene) nanosupports for indometacin and their potential inclusion in eye drops. The polymers are synthesized as nanosized latex by a radical polymerization of the monomers in the presence of indometacin. It is proved that the low polymerization temperature and initiator used do not influence indometacin structure and properties. The nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopic analyses, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The size of the latex particles was around 200 nm, determined by the scan electron microscopy. The indometacin delivery rate from the supports discussed in aqueous solutions was determined at pH 7.4. The change of this rate, in comparison with that for a pure drug substance, was established also as well as its dependence on the nature of the carrier. PMID:22888516

Andonova, V; Georgiev, G; Toncheva, V; Kassarova, M

2012-07-01

25

Poly(vinyl chloride) blend with biodegradable cellulose acetate in presence of N-(phenyl amino) maleimides.  

PubMed

Wider plastic applications of poly(vinyl chloride) (PVC) has raised serious problem to the environment. Since (PVC) waste products resist biodegradation and persist in the environment for longer time. The object of this study is to blend (PVC) with biodegradable cellulose acetate to thermally support the polymer during the molding process as well as to enhance the biodegradability of (PVC) waste products. Blending of poly(vinyl chloride) and cellulose acetate (CA) in presence of N-(phenyl amino) maleimides (R-PhAM) where (R=H, 4-NO2) led to improvement in the thermal stability of the blend film at high temperatures as shown from the high values of initial decomposition temperature (To) determined from their thermogravimetry (TG) curves. Also, blending (PVC) with (CA) led to improvement in the mechanical properties of the blend films as compared to (PVC). The crystalline regions of cellulose acetate enhanced the elasticity of the blend films as shown from their high Young's modulus values. PMID:24973650

Abdel-Naby, Abir S; Al-Ghamdi, Azza A

2014-09-01

26

Effect of poly(vinyl acetate-acrylamide) microspheres properties and steric hindrance on the immobilization of Candida rugosa lipase.  

PubMed

Poly(vinyl acetate-acrylamide) microspheres were synthesized in the absence or presence of isooctane via suspension polymerization and utilized as carriers to immobilize Candida rugosa lipase. When the hydrophobic/hydrophilic surface characteristics of the microspheres were modified by changing the ratio of vinyl acetate (hydrophobic monomer) to acrylamide (hydrophilic monomer) from 50:50 to 86:24, the immobilization ratio changed from 45% to 92% and the activity of the immobilized lipase increased from 202.5 to 598.0 U/g microsphere. Excessive lipase loading caused intermolecular steric hindrance, which resulted in a decline in lipase activity. The maximum specific activity of the immobilized lipase (4.65 U/mg lipase) was higher than that of free lipase (3.00 U/mg lipase), indicating a high activity recovery during immobilization. PMID:22989650

Zhang, Dong-Hao; Yuwen, Li-Xia; Li, Chao; Li, Ya-Qiong

2012-11-01

27

Polyvinyl Alcohol Hydrogel Irradiated and Acetalized for Osteochondral Defect Repair: Mechanical, Chemical, and Histological Evaluation after Implantation in Rat Knees  

PubMed Central

Polyvinyl Alcohol (PVA) hydrogel plugs were implanted in artificial osteochondral defects on the trochlear groove of rat knees. After 0, 3, 6, 12, and 24 weeks of followup, samples containing the implants were mechanically evaluated by creep indentation test, chemically, and histologically by optical microscopy. The mechanical test pointed towards an increase of the implant creep modulus and the chemical analysis exhibited an increasing concentration of calcium and phosphorus within the implants over time. Optical microscopy showed no foreign body reaction and revealed formation, differentiation, and maintenance of new tissue at the defect/implant interface. The absence of implant wear indicated that the natural articular lubrication process was not disturbed by the implant. The performance of the irradiated and acetalized PVA was considered satisfactory for the proposed application. PMID:23197982

Batista, N. A.; Rodrigues, A. A.; Bavaresco, V. P.; Mariolani, J. R. L.; Belangero, W. D.

2012-01-01

28

Aspects of the performance of PVAc adhesives in wood joints  

Microsoft Academic Search

Various modifications of polyvinyl acetate emulsion wood adhesive were made and their performance evaluated in standard tests. The results are interpreted in the context of adhesion theories and the chemical structures of the polymers and wood. The adhesion of the polymers to wood and the cohesive strength of the polymers are the two predominant factors determining the performance of the

Lijun Qiao; Allan J. Easteal

2001-01-01

29

Comparative Study on the Efficacy of Gingival Retraction using Polyvinyl Acetate Strips and Conventional Retraction Cord - An in Vivo Study  

PubMed Central

Statement of Problem: A new material is proposed in dentistry in the form of strips for producing gingival retraction. The clinical efficacy of the material remains untested. Purpose of the Study: This study aimed to determine whether the polyvinyl acetate strips are able to effectively displace the gingival tissues in comparison with the conventional retraction cord. Material and Methods: Complete metal ceramic preparation with supra-gingival margin was performed in fourteen maxillary incisors and gingival retraction was done using Merocel strips and conventional retraction cords alternatively in 2 weeks time interval. The amount of displacement was compared using a digital vernier caliper of 0.01mm accuracy. Results were analyzed statistically using Paired students t-test. Results: The statistical analysis of the data revealed that both the conventional retraction cord and the Merocel strip produce significant retraction. Among both the materials, Merocel proved to be significantly more effective. Conclusion: Merocel strip produces more gingival displacement than the conventional retraction cord. PMID:24298531

Shivasakthy, M.; Asharaf Ali, Syed

2013-01-01

30

Preparation and characterization of poly(vinyl chloride-co-vinyl acetate)-based gel electrolytes for Li-ion batteries  

SciTech Connect

Poly(vinyl chloride) (PVC)-based electrolytes, a class of the most promising polymer electrolytes, are found to suffer from solvent exudation. Two strategies were employed to suppress this shortcoming, one involving the replacement of PVC with poly(vinyl chloride-co-vinyl acetate) (PVCAC) copolymer and the other the direct utilization of solvents for PVC or PVCAC instead of using an auxiliary carrier solvent (e.g., tetrahydrofuran, THF). The thermodynamics of polymer solubility was particularly emphasized in the latter approach. N,N-dimethylformamide (DMF) and N-methyl pyrrolidionone (NMP) are preferred cosolvents of ethylene carbonate (EC) and/or propylene carbonate (PC). The PVCAC-based gel electrolytes prepared were then characterized by ionic conductivity, cyclic voltammetry, and ac impedance data. The results indicate that electrolytes containing NMP/EC mixed solvent exhibit conductivities exceeding 10{sup {minus}3} S/cm whereas the electrolytes containing DMF/EC/PC exhibit conductivities around 10{sup {minus}4} S/cm at room temperature. Moreover, the former category was found to be oxidatively stable up to 4.9 V vs. Li/Li{sup +} and the latter to 4.6 V vs. Li/Li{sup +}. Finally, ac impedance results suggest that the stability of the Li/electrolyte interface needs further improvement, which is a crucial task for most polymer gel electrolytes at present.

Sung, H.Y.; Wang, Y.Y.; Wan, C.C. [National Tsing-Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Chemical Engineering

1998-04-01

31

Micro Raman, 7Li NMR and ac Impedance Analysis of PVAC:LiClO4 Solid Polymer Electrolytes  

NASA Astrophysics Data System (ADS)

The polymer electrolytes composed of Poly (vinyl acetate) (PVAc) with various stoichiometric ratios of lithium perchlorate (LiClO4) salt have been prepared by solution casting method. The techniques Fourier Transform Infra-red (FTIR) and micro Raman spectroscopy have been used to study polymer- salt complex formation, ion-ion and ion-polymer interactions as a function of salt concentration The ac impedance results show the depressed semicircles which indicate the non-Debye nature of the polymer electrolytes. The maximum ionic conductivity has been found to be 1.3×10-3 Scm-1 at 373K for the 80PVAc:20LiClO4 polymer complex. The 7Li NMR linewidth decreases with increasing temperature which indicates the enhancement of lithium ion mobility in the polymer electrolytes. The two different environments of Li+ ion in the polymer electrolytes observed in 7Li NMR have been confirmed by FTIR analysis.

Baskaran, R.; Selvasekarapandian, S.; Kuwata, N.; Kamishima, O.; Kawamura, J.; Hattori, T.

2006-06-01

32

Safety of PVAP and PVAP-T including a 90-day dietary toxicity study in rats and genotoxicity tests with polyvinyl acetate phthalate (PVAP).  

PubMed

The safety of PVAP was evaluated in a 90-day subchronic toxicity study in rats. Sprague Dawley Crl:CD(SD) rats were administered a dietary concentration of 0.75%, 1.5% and 5.0% PVAP for a minimum of 90days. There were no adverse effects reported. The no-observed-adverse-effect level (NOAEL) in the 90-day sub chronic study was the 5% dietary concentration, which corresponds to a dose of 3120mg/kg/day for males and 3640mg/kg/day for females, the highest level tested. PVAP is co-processed with titanium dioxide to produce polyvinyl acetate phthalate and titanium dioxide (PVAP-T). The chemical composition, physiochemical properties and specifications of PVAP-T are unchanged during manufacturing process based on various analytical studies. Therefore, the toxicological data that support the safety of PVAP can be used to support the use of PVAP-T as a pharmaceutical excipient. An independent expert panel evaluated the safety of PVAP and PVAP-T. Based on the toxicology study results, safety assessment and the estimated exposure assessment for PVAP and PVAP-T, the expert panel concluded that PVAP and PVAP-T could safely be used in drug products up to 829mg per day which was the estimated exposure provided to the expert panel for current applications of PVAP and PVAP-T. PMID:24813760

DeMerlis, C C; Schoneker, D R; Borzelleca, J F

2014-08-01

33

Estimation of polyvinyl alcohol cryogel mechanical properties with four ultrasound elastography methods and comparison with gold standard testings  

Microsoft Academic Search

Tissue-mimicking phantoms are very useful in the field of tissue characterization and essential in elastography for the purpose of validating motion estimators. This study is dedicated to the characterization of polyvinyl alcohol cryogel (PVA-C) for these types of applications. A strict fabrication procedure was defined to optimize the reproducibility of phantoms having a similar elasticity. Following mechanical stretching tests, the

Jeremie Fromageau; Jean-Luc Gennisson; Cedric Schmitt; Roch L. Maurice; Rosaire Mongrain; G. Cloutier

2007-01-01

34

Modifying the MRI, elastic stiffness and electrical properties of polyvinyl alcohol cryogel using irradiation  

NASA Astrophysics Data System (ADS)

The aim of this work was to study the effect of radiation on the elastic stiffness, electrical and MRI properties of polyvinyl alcohol (PVA)-based cryogel (PVA-C). The PVA-C samples were irradiated with a 60C0 ?-source, at 2.18 × 10 6 Rads. The indentation measurements (an indication of elastic stiffness) reduced by about 14.6% for PVA-3C and 5.7% PVA-6C after irradiation, indicating that the material became harder/stiffer. It was found that MRI relaxation times provide an alternative and non-destructive method to evaluate the radiation effect on PVA-C. The T1 of PVA-C that had undergone three freeze thaw cycles decreased with irradiation by 10%, 25% and 35% at 1 T, 1.89 T and 3 T respectively. The T1 of PVA-C that had undergone six freeze thaw cycles decreased with irradiation by 18%, 15% and 11% at 1 T, 1.89 T and 3 T respectively. The T2 of PVA-C decreased with irradiation only at 1 T, however this change is hypothesized to be due to the interaction of two spin pools in the gel. The electrical conductivity ( ?) and permittivity constant ( ?) of the unirradiated and ?-irradiated PVA-C samples were measured at different frequencies in the range 40 Hz to 1 MHz. The results demonstrated that the conductivity increased with irradiation by 50% for PVA-3C (three freeze thaw cycles) and 75% for PVA-6C (six freeze thaw cycles) at frequencies greater than 1 KHz.The permittivity decreased with irradiation up to 25% for 3C and 35% for 6C at frequencies less than 1 KHz.

Goharian, Mehran; Moran, Gerald R.; Wilson, Kyle; Seymour, Colin; Jegatheesan, Aravinthan; Hill, Michael; Thompson, R. Terry; Campbell, Gordon

2007-10-01

35

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

36

Poly(vinyl alcohol) cryogel phantoms for use in ultrasound and MR imaging  

NASA Astrophysics Data System (ADS)

Poly(vinyl alcohol) cryogel, PVA-C, is presented as a tissue-mimicking material, suitable for application in magnetic resonance (MR) imaging and ultrasound imaging. A 10% by weight poly(vinyl alcohol) in water solution was used to form PVA-C, which is solidified through a freeze-thaw process. The number of freeze-thaw cycles affects the properties of the material. The ultrasound and MR imaging characteristics were investigated using cylindrical samples of PVA-C. The speed of sound was found to range from 1520 to 1540 m s-1, and the attenuation coefficients were in the range of 0.075-0.28 dB (cm MHz)-1. T1 and T2 relaxation values were found to be 718-1034 ms and 108-175 ms, respectively. We also present applications of this material in an anthropomorphic brain phantom, a multi-volume stenosed vessel phantom and breast biopsy phantoms. Some suggestions are made for how best to handle this material in the phantom design and development process.

Surry, K. J. M.; Austin, H. J. B.; Fenster, A.; Peters, T. M.

2004-12-01

37

Synthesis of light-selective poly(ethylene-co-vinyl acetate) nanofilms in supercritical carbon dioxide  

NASA Astrophysics Data System (ADS)

Due to the increased requirements of environmental protection, significant effort has been made to develop new "green" chemistry and engineering methods. Two effective approaches for "green" processes are: (1) to employ routes with fewer synthetic and separation steps, and (2) to replace volatile organic solvents with environmentally friendly solvents. Supercritical carbon dioxide (scCO2) has emerged as such a viable "green" alternative to organic solvents for several applications including extraction, polymerization, and nanotechnology, etc. In addition, it is an enabling solvent, allowing new types of chemistry and materials to be formed. In order to effectively utilize scCO2, it is required to study its effect on the relevant chemical process. This thesis focuses on the copolymerization of ethylene and vinyl acetate in scCO2, and the application of scCO2 in the synthesis of novel poly(vinyl acetate) (PVAc) and poly(ethylene-co-vinyl acetate) (PEVA) nanocomposites. Firstly, the kinetics of the process was investigated. The thermal decomposition of the free-radical initiator diethyl peroxydicarbonate (DEPDC) was monitored by in situ attenuate total reflection Fourier transform infrared spectroscopy (ATR-FTIR) in heptane, and in scCO2. The rate constant and activation energy of the thermal decomposition of DEPDC in scCO2 were determined, and a decomposition mechanism was proposed. Further, with a knowledge of the initiator kinetics, in situ ATR-FTIR was employed to monitor the initial formation of copolymers of ethylene and vinyl acetate during polymerization in scCO2. The reactivity ratios for the copolymerization of ethylene and vinyl acetate in scCO2 were determined using both the Kelen-Tudos and the non-linear least-squares methods. The potential of scCO2 was further examined to synthesize advanced and novel nanomaterials based on an understanding of the polymerization mechanism. A novel one-step synthesis route was developed for making silica-PVAc nanocomposites in scCO2, where the parallel reactions of free radical polymerization, hydrolysis/condensation, and linkage of the nanoparticles to the polymer chains, were found to take place simultaneously. This provides a new process featuring significant energy-saving, waste-reduction, and excellent distribution of nanoparticles in the polymer matrix. In addition, the incorporation of quantum dots (QDs) into a transparent polymer matrix was investigated to form light-selective nanofilms. Both CdS and CdS-ZnS core-shell QDs were synthesized, then functionalized with a methoxysilane group, and finally used to synthesize novel QD-PVAc and QD-PEVA nanocomposites in scCO2. The synthesized QD-PEVA nanofilms displayed significant absorption in the ultraviolet and violet regions of the electromagnetic spectrum, while providing a characteristic emission in the region from orange to red light. These materials have significant potential in green houses, and solar absorber films. Key words. supercritical CO2, initiator, thermal decomposition, kinetics, mechanism, ATR-FTIR, reactivity ratios, ethylene, vinyl acetate, silica, nanocomposite, one-pot synthesis, light-selective, nanofilm, quantum dots.

Xu, William (Zhiming)

38

Preparation and properties of poly(vinyl alcohol)/chitosan blend bionanocomposites reinforced with cellulose nanocrystals/ZnO-Ag multifunctional nanosized filler.  

PubMed

A series of novel bionanocomposites were cast using different contents of zinc oxide-silver nanoparticles (ZnO-AgNPs) stabilized by cellulose nanocrystals (CNC) as multifunctional nanosized fillers in poly(vinyl alcohol)/chitosan (PVA/Cs) matrices. The morphological structure, mechanical properties, ultraviolet-visible absorption, and antimicrobial properties of the prepared films were investigated as a function of their CNC/ZnO-AgNP content and compared with PVA/chitosan/CNC bionanocomposite films. X-ray diffraction and field emission scanning electron microscopic analyses showed that the CNC/ZnO-AgNPs were homogeneously dispersed in the PVA/Cs matrix and the crystallinity increased with increasing nanosized filler content. Compared with pure PVA/Cs, the tensile strength and modulus in the films increased from 0.055 to 0.205 GPa and from 0.395 to 1.20 GPa, respectively. Ultraviolet and visible light can be efficiently absorbed by incorporating ZnO-AgNPs into a PVA/Cs matrix, suggesting that these bionanocomposite films show good visibility and ultraviolet-shielding effects. The bionanocomposite films had excellent antimicrobial properties, killing both Gram-negative Salmonella choleraesuis and Gram-positive Staphylococcus aureus. The enhanced physical properties achieved by incorporating CNC/ZnO-AgNPs could be beneficial in various applications. PMID:24790433

Azizi, Susan; Ahmad, Mansor Bin; Hussein, Mohd Zobir; Ibrahim, Nor Azowa; Namvar, Farideh

2014-01-01

39

Cellulose nanocrystals/ZnO as a bifunctional reinforcing nanocomposite for poly(vinyl alcohol)/chitosan blend films: fabrication, characterization and properties.  

PubMed

In this study, cellulose nanocrystals/zinc oxide (CNCs/ZnO) nanocomposites were dispersed as bifunctional nano-sized fillers into poly(vinyl alcohol) (PVA) and chitosan (Cs) blend by a solvent casting method to prepare PVA/Cs/CNCs/ZnO bio-nanocomposites films. The morphology, thermal, mechanical and UV-vis absorption properties, as well antimicrobial effects of the bio-nanocomposite films were investigated. It demonstrated that CNCs/ZnO were compatible with PVA/Cs and dispersed homogeneously in the polymer blend matrix. CNCs/ZnO improved tensile strength and modulus of PVA/Cs significantly. Tensile strength and modulus of bio-nanocomposite films increased from 55.0 to 153.2 MPa and from 395 to 932 MPa, respectively with increasing nano-sized filler amount from 0 to 5.0 wt %. The thermal stability of PVA/Cs was also enhanced at 1.0 wt % CNCs/ZnO loading. UV light can be efficiently absorbed by incorporating ZnO nanoparticles into a PVA/Cs matrix, signifying that these bio-nanocomposite films show good UV-shielding effects. Moreover, the biocomposites films showed antibacterial activity toward the bacterial species Salmonella choleraesuis and Staphylococcus aureus. The improved physical properties obtained by incorporating CNCs/ZnO can be useful in variety uses. PMID:24945313

Azizi, Susan; Ahmad, Mansor B; Ibrahim, Nor Azowa; Hussein, Mohd Zobir; Namvar, Farideh

2014-01-01

40

A novel ceramic-supported polymer membrane for pervaporation of dilute volatile organic compounds  

Microsoft Academic Search

A novel asymmetric ceramic-supported polymer (CSP) pervaporation membrane was developed using free-radical graft polymerization of polyvinyl acetate (PVAc) onto a porous tubular silica substrate. The resulting membrane was characterized by pervaporation removal of trichloroethylene (TCE) and chloroform from dilute aqueous solutions. PVAc was chosen since it has a high affinity for TCE and chloroform and a low affinity for water,

Jeng-Dung Jou; Wayne Yoshida; Yoram Cohen

1999-01-01

41

SOURCE ASSESSMENT: POLYVINYL CHLORIDE  

EPA Science Inventory

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

42

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

43

Adhesion properties of eco-friendly PVAc emulsion adhesive using nonphthalate plasticizer  

Microsoft Academic Search

An eco-friendly poly (vinyl acetate) emulsion adhesive was synthesized without phthalate. Four types of eco-friendly plasticizers for use in these adhesives were selected to confirm their primary properties by injecting the eco-friendly plasticizer without any prior change to its processing or cost. The four types of eco-friendly plasticizers used were dibutyl phthalate DBP-based product, dialkyl ester, acetyl tributyl citrate, and

Youn-Mee Choi; Byoung-Ho Lee; Ji-Won Park; Hyun-Joong Kim; Young Geun Eom; Sung-Wook Jang; Young-Kyu Lee

2012-01-01

44

Characterisation of the Poly(Vinylpyrrolidone)Poly(Vinylacetate-Co-Crotonic Acid) (PVP:PVAc-CA) Interpolymer Complex Matrix Microparticles Encapsulating a Bifidobacterium lactis Bb12 Probiotic Strain  

Microsoft Academic Search

The method of producing poly-(vinylpyrrolidone)-poly-(vinylacetate-co-crotonic acid) (PVP:PVAc-CA) interpolymer complex matrix\\u000a microparticles in supercritical carbon dioxide (scCO2), encapsulating bacteria, has recently been developed. This study was aimed at probing the external and internal structure\\u000a of these microparticles, which can be used in food. The encapsulation efficiency and distribution of encapsulated Bifidobacterium lactis Bb12 within these microparticles were also investigated. Scanning electron

C. I. Mamvura; F. S. Moolman; L. Kalombo; A. N. Hall; M. S. Thantsha

2011-01-01

45

75 FR 61175 - Polyvinyl Alcohol From Taiwan  

Federal Register 2010, 2011, 2012, 2013

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

2010-10-04

46

21 CFR 177.1670 - Polyvinyl alcohol film.  

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

2014-04-01

47

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

48

DESOXYCORTICOSTERONE ACETATE  

PubMed Central

1. Desoxycorticosterone acetate (DCA) and NaCl, in the dosage employed in normal rats, caused renal and cardiac hypertrophy, characteristic changes in the renal tubular epithelium, atrophic changes in the subcapsular zone of the adrenal cortex, and serum electrolyte changes characterized by a rise in sodium and fall in potassium. 2. In rats rendered nephritic with a rabbit anti-rat-kidney serum, the same regimen caused similar changes. In addition, DCA given concurrently with NaCl greatly intensified the nephritic process and gave rise to striking arterial hypertension. 3. A diet, virtually sodium-free, administered to normal and nephritic rats receiving daily injections of DCA abolished or reduced to a minimum the effects of this steroid; i.e., a liberal ingestion of NaCl was essential for the potentiation of the action of DCA. 4. The addition of KCl to the drinking water of rats receiving DCA and NaCl tended to correct the depression of the level of potassium in the serum, but had no effect upon the hypertension in nephritic animals nor upon the anatomical lesions. 5. The mechanism by which the sodium ion potentiates the activity of DCA has not been established. PMID:19871607

Knowlton, Abbie I.; Loeb, Emily N.; Stoerk, Herbert C.; Seegal, Beatrice C.

1947-01-01

49

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

Microsoft Academic Search

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

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

2003-01-01

50

Three methods for in situ cross-linking of polyvinyl alcohol films for application as ion-conducting membranes in potassium hydroxide electrolyte. [battery separators  

NASA Technical Reports Server (NTRS)

Three methods of in situ cross-linking polyvinyl alcohol films are presented. They are: (1) acetalization with a dialdehyde such as glutaraldehyde, (2) acetalization with aldehyde groups formed by selective oxidative cleaving of the few percent of 1,2 diol units present in polyvinyl alcohol, and (3) cross-linking by hydrogen abstraction by reaction with hydrogen atoms and hydroxyl radicals from irradiated water. For the third method, improvement in film conductivity in KOH solution at the expense of mechanical strength is obtained by the presence of polyacrylic acid in the polyvinyl alcohol films. Resistivities in 45 percent KOH are given for in situ cross-linked films prepared by each of the three methods.

Philipp, W. H.; Hsu, L. C.

1979-01-01

51

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

Federal Register 2010, 2011, 2012, 2013

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

2011-02-01

52

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

53

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

54

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

55

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

56

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

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

2014-04-01

57

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

58

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

59

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

Federal Register 2010, 2011, 2012, 2013

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

2011-03-15

60

Effect of Renal Embolization with Trisacryl and PAVc  

PubMed Central

OBJECTIVES Evaluate the degree of vascular occlusion, vascular recanalization, and necrosis of the vascular wall caused by polyvinyl alcohol-covered polyvinyl acetate (PVAc) particles compared to trisacryl particles after renal embolization. METHODS Seventy-nine female albino New Zealand rabbits underwent arterial catheterization of the right kidney. Thirty-three animals were embolized with trisacryl particles, thirty-one with PVAc particles, and fifteen were kept as controls. Four animals were excluded (three trisacryl and one PVAc) due to early death. Five subgroups of six animals were created. The animals in the different groups were sacrificed either 48 hours, 5 days, 10 days, 30 days, or 90 days after embolization. The control group was divided into subgroups of three animals each and kept for the same periods of time. The kidneys were dyed with hematoxylin-eosin and Masson’s trichrome and then examined using optical microscopy. RESULTS There were significant differences in the degree of vascular occlusion caused by the trisacryl and the PVAc particles between the five-day and the ten-day groups. Additional differences were noted between the five-day and 48-hour groups in regard to the amount of necrosis. For both findings, the PVAc group members showed adequate tissue reaction (ischemia and volumetric reduction) and less recanalization than those treated with trisacryl. CONCLUSION The use of PVAc as an embolization material exhibited an adequate tissue reaction (ischemia and volumetric reduction), more expressive vascular occlusion and necrosis, and less recanalization than the trisacryl material. PMID:19936185

de Assis Barbosa, Leandro; Caldas, Jose Guilherme Mendes Pereira; Conti, Mario Luiz; Malheiros, Denise Maria Avancini Costa; Ramos, Francisco Ferreira

2009-01-01

61

Preparation of polymer decorated graphene oxide by ?-ray induced graft polymerization.  

PubMed

Herein, we report a facile approach to decorate graphene oxide (GO) sheets with poly(vinyl acetate) (PVAc) by ?-ray irradiation-induced graft polymerization. The content of PVAc in the obtained sample, i.e., PVAc grafted GO (GO-g-PVAc) is calculated by the loss weight in thermogravimetric analysis (TGA) curves. A GO-g-PVAc sample with a degree of grafting (DG) of 28.5% was well dispersed in common organic solvents and the dispersions obtained were extremely stable at room temperature without any aggregation, even after standing for 2 months. The excellent dispersibility and stability of GO-g-PVAc in common organic solvents are readily rationalized in terms of the full coverage of PVAc chains and solvated layer formation on graphene oxide sheets surface, which weakens the interlaminar attraction of GO sheets. This approach presents a facile route for the preparation of dispersible GO and shows great potential in the preparation of graphene-based composites by solution-processes. PMID:22307684

Zhang, Bowu; Zhang, Yujie; Peng, Cheng; Yu, Ming; Li, Linfan; Deng, Bo; Hu, Pengfei; Fan, Chunhai; Li, Jingye; Huang, Qing

2012-03-01

62

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

Federal Register 2010, 2011, 2012, 2013

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

2013-04-08

63

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

Federal Register 2010, 2011, 2012, 2013

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

2013-07-01

64

Effect of Heat Treatment on Some Mechanical Properties of Laminated Window Profiles Manufactured Using Two Types of Adhesives  

PubMed Central

The mechanical properties of laminated window profiles manufactured using two types of adhesives were determined. The objective of this study is to evaluate the effects of heat treatment on some mechanical properties of laminated window profiles that manufactured from Kosipo (Entandrophragma candollei Harms.) using differenet type adhesives. Commercially produced polyurethane based Macroplast UR 7221 and polyvinyl acetate (PVAc) adhesive were used for experiments. The overall test results were found to be comparable to those obtained in the previous studies. Both types of adhesives resulted in significant differences in their strength characteristics at 95% confidence level. Adhesive UR 7221 improved the overall properties of the samples in contrast to PVAc. PMID:19325761

Korkut, Derya Sevim; Korkutand, Suleyman; Dilik, Tuncer

2008-01-01

65

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

PubMed

A novel nanocomposite polyvinyl alcohol precursor-based material dispersed with the web of carbon microfibers and carbon nanofibers is developed as lithium (Li)-ion electrolyte battery separator. The primary synthesis steps of the separator material consist of esterification of polyvinyl acetate to produce polyvinyl alcohol gel, ball-milling of the surfactant dispersed carbon micro-nanofibers, mixing of the milled micron size (~500 nm) fibers to the reactant mixture at the incipience of the polyvinyl alcohol gel formation, and the mixing of hydrophobic reagents along with polyethylene glycol as a plasticizer, to produce a thin film of ~25 ?m. The produced film, uniformly dispersed with carbon micro-nanofibers, has dramatically improved performance as a battery separator, with the ion conductivity of the electrolytes (LiPF6) saturated film measured as 0.119 S-cm(-1), approximately two orders of magnitude higher than that of polyvinyl alcohol. The other primary characteristics of the produced film, such as tensile strength, contact angle, and thermal stability, are also found to be superior to the materials made of other precursors, including polypropylene and polyethylene, discussed in the literature. The method of producing the films in this study is novel, simple, environmentally benign, and economically viable. PMID:23827627

Sharma, Ajit K; Khare, Prateek; Singh, Jayant K; Verma, Nishith

2013-04-01

66

The Acetate Switch  

PubMed Central

To succeed, many cells must alternate between life-styles that permit rapid growth in the presence of abundant nutrients and ones that enhance survival in the absence of those nutrients. One such change in life-style, the “acetate switch,” occurs as cells deplete their environment of acetate-producing carbon sources and begin to rely on their ability to scavenge for acetate. This review explains why, when, and how cells excrete or dissimilate acetate. The central components of the “switch” (phosphotransacetylase [PTA], acetate kinase [ACK], and AMP-forming acetyl coenzyme A synthetase [AMP-ACS]) and the behavior of cells that lack these components are introduced. Acetyl phosphate (acetyl?P), the high-energy intermediate of acetate dissimilation, is discussed, and conditions that influence its intracellular concentration are described. Evidence is provided that acetyl?P influences cellular processes from organelle biogenesis to cell cycle regulation and from biofilm development to pathogenesis. The merits of each mechanism proposed to explain the interaction of acetyl?P with two-component signal transduction pathways are addressed. A short list of enzymes that generate acetyl?P by PTA-ACKA-independent mechanisms is introduced and discussed briefly. Attention is then directed to the mechanisms used by cells to “flip the switch,” the induction and activation of the acetate-scavenging AMP-ACS. First, evidence is presented that nucleoid proteins orchestrate a progression of distinct nucleoprotein complexes to ensure proper transcription of its gene. Next, the way in which cells regulate AMP-ACS activity through reversible acetylation is described. Finally, the “acetate switch” as it exists in selected eubacteria, archaea, and eukaryotes, including humans, is described. PMID:15755952

Wolfe, Alan J.

2005-01-01

67

Effect of provisional luting agents on polyvinyl siloxane impression material  

Microsoft Academic Search

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

Rodney H Jones; Gregory S Cook; Marty G Moon

1996-01-01

68

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

Microsoft Academic Search

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

Daniel Bondeson; Kristiina Oksman

2007-01-01

69

Complex compound polyvinyl alcohol-titanic acid/titanium dioxide  

NASA Astrophysics Data System (ADS)

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

Prosanov, I. Yu.

2013-02-01

70

Enthalpy of dilution of poly(vinyl acetate) in 1,2-dichloroethane  

NASA Astrophysics Data System (ADS)

This document is part of Subvolume D2 'Polymer Solutions - Physical Properties and their Relations I (Thermodynamic Properties: PVT -Data and miscellaneous Properties of polymer Solutions) of Volume 6 `Polymers' of Landolt-Börnstein - Group VIII `Advanced Materials and Technologies'.

Wohlfarth, Ch.

71

Dissection and hemostasis with hydroxilated polyvinyl acetal tampons in open thyroid surgery  

Microsoft Academic Search

BACKGROUND: The essential objectives for thyroidectomy are: avoidance of injury to the recurrent laryngeal nerves, conservation of the parathyroid glands, an accurate haemostasis and an excellent cosmesis. In the last 10 years major improvements and new technologies have been proposed and applied in thyroid surgery; among these mini-invasive thyroidectomy, regional anaesthesia and intraoperative neuromonitoring, and new devices for achieving dissection

Gianlorenzo Dionigi; Luigi Boni; Francesca Rovera; Renzo Dionigi

2007-01-01

72

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

E-print Network

integrity of these objects and the cultural information that they contain, these objects require. Sandstone slabs were especially used while cooking in earth ovens because of their ability to absorb heat for the Native Americans while cooking food, it also caused considerable damage to the sandstones as artifacts

Rock, Chris

73

[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

74

Synthesis and characterization of magnetic nanoparticles embedded in polyvinyl pyrrolidone nanofiber film by electrospinning method  

NASA Astrophysics Data System (ADS)

We fabricated magnetic nanofiber films by manufacturing the nanoparticles with the polyol process followed by the electrospinning process to combine them into a thin film. The magnetite (Fe3O4) nanoparticles with mean crystallite size of 6-8 nm were synthesized through reduction of iron (II) acetate in the polyols and using polyvinyl pyrrolidone (PVP) as the protecting agent. The PVP-coated Fe3O4 nanoparticles were dispersed into PVP ethanol solution and then electrospun directly to make nanofiber films. The diameters of fibers range between 200-400 nm, and the film thickness is about 50 ?m. The Fe3O4 nanoparticles show a saturation magnetization of 36.6 emu/g, and together with the nanofiber films display a superparamagnetic behavior.

Lin, Chun-Rong; Tsai, Tsu-Chi; Chung, Max; Lu, Shih-Zong

2009-04-01

75

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

76

Acidbase interaction in the acetic acid-acetic anhydride system  

Microsoft Academic Search

1.The electroconductivity and dielectric permeability of the acetic acid-acetic anhydride system have been measured. The electroconductivity of the system has a maximum close to 50% of the anhydride. The curve of the dielectric permeability is concave toward the composition axis.2.The dependence of the electroconductivity on the composition is explained by the formation of a complex between acetic acid and acetic

V. E. Bel'skii; M. I. Vinnik

1963-01-01

77

Hologram with dichromated polyvinyl alcohol and natural colorant  

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

78

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

79

Impacts of impregnation chemicals on combustion properties of the laminated wood materials produced combination of beech and poplar veneers  

Microsoft Academic Search

The aim of this study was to investigate the effects of impregnation with boron compounds Borax (BX), Boric acid (BA), BX+BA, Imersol-Aqua (IAQUA) and Timbercare-Aqua (TAQUA) on combustion properties of the laminated wood materials produced combination of Oriental beech and poplar veneers bonded with Desmodur-VTKA (DV) and Poly(vinyl acetate) (PVAc) adhesives. The test samples, prepared from beech (Fagus orientalis Lipsky)

Hakan Keskin; Musa Atar; Mahmut Izciler

2009-01-01

80

Impacts of impregnation with boron compounds on the bonding strength of wood materials  

Microsoft Academic Search

The objective of this research was to evaluate bonding strength of poly(vinyl acetate) (PVAc), polyurethane based Desmodur-VTKA (D-VTKA), phenol–formaldehyde (PF) and melamine–formaldehyde (MF) adhesives to impregnated wood materials. For this purpose, oriental beech (Fagus orientalis lipsky), white oak (Quercus petraea spp.), Uludag fir (Abies bornmülleriana Mattf.) and poplar (Populus nigra) woods were impregnated with borax (Bo), boric acid (Ba), Bo+Ba

Ayhan Özçifçi

2008-01-01

81

Bondability of tropical fast-growing tree species I: Indonesian wood species  

Microsoft Academic Search

To estimate the potential bonding performance of bonded wood products from tropical fast-growing tree species, a study on\\u000a the bondability of Paraserianthes falcataria L. Nielsen, Pinus merkusii Jungh et. De. Vriese, and Acacia mangium Willd from Indonesia was conducted. Two-ply laminations were produced using polyvinyl acetate emulsion (PVAc), urea formaldehyde\\u000a (UF), resorcinol formaldehyde (RF), and water-based polymer isocyanate (API) adhesives.

Eka Mulya Alamsyah; Liu Chang Nan; Masaaki Yamada; Kinji Taki; Hiroaki Yoshida

2007-01-01

82

Effect of nano-sized silver particles on the resistivity of polymeric conductive adhesives  

Microsoft Academic Search

In this work, conductive adhesives were made by adding micro-sized silver flakes, mixed-sized silver particles or nano-sized silver colloids to the polyvinyl acetate (PVAc) emulsion. Film resistivity was then measured as a function of silver volume fraction. Our results indicated that the addition of nano-sized silver colloids to micro-sized Ag flakes usually increased its resistivity, probably due to increased contact

Hsien-Hsuen Lee; Kan-Sen Chou; Zong-Whie Shih

2005-01-01

83

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

PubMed

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

Seabra, Amedea Barozzi; De Oliveira, Marcelo Ganzarolli

2004-08-01

84

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

Federal Register 2010, 2011, 2012, 2013

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

2010-09-13

85

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

Federal Register 2010, 2011, 2012, 2013

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

2013-06-24

86

The polyvinyl alcohol sponge model implantation.  

PubMed

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

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

2012-01-01

87

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

88

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.

89

Acetic Acid Catalyzed Carbon Aerogels  

Microsoft Academic Search

We prepared carbon aerogels with a wide range of structural properties and densities using the weak acetic acid as a catalyst. Two series of acetic acid catalyzed carbon aerogels with different dilution of the catalyst and the monomers were investigated accurately. Structural investigation was performed via (U)SAXS, gas sorption and SEM. The pore and particle size can be tailored according

R. Brandt; R. Petricevic; H. Pröbstle; J. Fricke

2003-01-01

90

Acetate metabolism in Methanothrix soehngenii  

Microsoft Academic Search

Acetate is quantitatively the most important intermediate in the anaerobic degradation of soluble organic matter. The conversion rate of acetate by methanogenic bacteria is proposed to be the rate limiting step in this degradation The study of acetoclastic methanogens, therefore is of relevance to our understanding of anaerobic processes and their optimal application in treatment of waste water from various

M. S. M. Jetten

1991-01-01

91

Acetic acid bacteria in oenology  

Microsoft Academic Search

Acetic acid bacteria have always been considered the bad mi- croorganisms of oenology; responsible for wine spoiling (vine- gary taint). The taxonomy and our knowledge of the metabo- lism of acetic acid bacteria are rapidly evolving, especially as new molecular biology techniques are applied to this fastidious group of microorganisms, which are still rather difficult to work with. The dramatic

A. Mas; M. J. Torija; A. González; M. Poblet; J. M. Guillamón

92

Respiratory illness caused by overheating of polyvinyl chloride  

Microsoft Academic Search

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

B Froneberg; P L Johnson; P J Landrigan

1982-01-01

93

Evaluation of a Polyvinyl Toluene Neutron Counter Array  

Microsoft Academic Search

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

Robert Hayes

2008-01-01

94

EXPOSURE TO CHEMICAL ADDITIVES FROM POLYVINYL CHLORIDE POLYMER EXTRUSION PROCESSING  

EPA Science Inventory

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

95

1 INTRODUCTION In Spain, Plasticized polyvinyl chloride (PVC-  

E-print Network

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

Zornberg, Jorge G.

96

Molecular Structure of Phenylmercuric acetate  

NSDL National Science Digital Library

Phenylmercuric acetate is white to white-yellow crystalline powder that is odorless. This phenyl mercury compound is used mainly as a fungicide, herbicide, slimicide and bacteriocide. Phenylmercuric acid serves as a preservative in canned paint, eye ointments and drops, injectable solutions, skin disinfectants and in cosmetics products such as hair shampoos, mouthwashes and toothpastes. It is also used in contraceptive gels and foams. Phenylmercuric acetate is prepared by interaction of benzene with mercuric acetate in glacial acetic acid. Phenylmercuric acetate's former production and use as a fungicide and as a mildew inhibitor in paints may have resulted in its direct release to the environment. This substance is very toxic to aquatic organisms and may be hazardous to the environment.

2004-11-10

97

Conductance of Dilute Sodium Acetate Solutions to 469 K and of Acetic Acid and Sodium Acetate\\/Acetic Acid Mixtures to 548 K and 20 MPa  

Microsoft Academic Search

In order to obtain accurate association constants for sodium acetate, a very precise flow method was used to measure the electrical conductivity of dilute aqueous solutions of sodium acetate at ambient conditions and 469 K and 20 MPa. Measurements at ambient conditions, 469 and 548 K and 20 MPa, were also made on sodium acetate\\/acetic acid mixtures and acetic acid.

G. H. Zimmerman; R. H. Wood

2002-01-01

98

Treatment of desizing wastewater containing poly(vinyl alcohol) by wet air oxidation  

SciTech Connect

The effectiveness of wet air oxidation (WAO) is studied in a 2-L autoclave for the treatment of desizing wastewater from man-made fiber textile plants. At an oxygen pressure of less than 2 MPa, over 30-min, chemical oxygen demand (COD) removal was found to increase from 15 to 65% when the temperature was raised from 150 to 250 C. The biodegradability of the wastewater was also simultaneously increased. Up to 90% of the COD could be removed within 120 min. A simplified reaction mechanism is proposed which involves a direct mineralization step in parallel with a step in which an intermediate is formed prior to mineralization. A kinetic model for COD removal was developed based on this reaction mechanism. The model was tested with experimental COD results over the temperature range of the experiments. The dependence of the specific reaction rate constants was found to follow the Arrhenius type of equation. The direct oxidation of poly(vinyl alcohol) (PVA) to carbon dioxide and water is the dominant reaction step. The intermediates formed are not likely to be the acetic acid but may be short segments of PVA that are easily oxidized.

Chen, G.; Lei, L.; Yue, P.L.; Cen, P.

2000-05-01

99

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

100

Electrically generated lead(IV) acetate and manganese(III) acetate as reagents for coulometric redox titrations in acetic acid  

Microsoft Academic Search

Summary The conditions were investigated for electrochemical generation of lead(IV) acetate in acetic acid by oxidation of lead(II) acetate on a lead dioxide electrode and on a platinum electrode. Bivalent manganese ions are quantitatively oxidized on a platinum electrode to the tervalent state in the same solvent. Coulometric titration methods for the determination of small amounts of hydroquinone in acetic

Tibor J. Pastor; Vilim J. Vajgand; Zorica Kicovic

1976-01-01

101

Accuracy of three polyvinyl siloxane putty-wash impression techniques  

Microsoft Academic Search

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

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

2000-01-01

102

Cross-linked polyvinyl alcohol films as alkaline battery separators  

Microsoft Academic Search

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

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

1983-01-01

103

Electrically Conducting Polymer-Copper Sulphide Composite Films, Preparation by Treatment of Polymer-Copper (2) Acetate Composites with Hydrogen Sulfide  

NASA Technical Reports Server (NTRS)

Polymer copper sulfide composite films were prepared by treatment of polymer poly(vinyl chloride), poly(acrylonitrile), copolymer of vinyl chloride and vinyl acetate (90:10), and ABS resin copper (2) acetate composites with hydrogen sulfide. The films showed electrical conductivity higher than 0.015 S/cm when they contained more than 20 wt percent of copper sulfide. A poly(acrylonitrile)-copper sulfide composite film containing 40 to 50 wt percent of copper sulfide showed electrical conductivity of 10 to 150.0 S/cm and had relatively high mechanical strength to be used in practical purposes.

Yamamoto, Takakazu; Kamigaki, Takahira; Kubota, Etsuo

1988-01-01

104

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria  

Microsoft Academic Search

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Ga. europaeus exhibited the highest resistance to acetic acid (10%), whereas Ga. intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal

Janja Trcek; Hirohide Toyama; Jerzy Czuba; Anna Misiewicz; Kazunobu Matsushita

2006-01-01

105

Improving performance of polyvinyl acetate (PVA) as a binder for wood by combination with melamine based adhesives  

Microsoft Academic Search

In this study blending PVA with MUF and MF was evaluated as an approach to enhance the performance of PVA towards water and elevated temperatures. MF and MUF were added to PVA at different proportions: 15%, 30%, 50%, 70% and 100%. Blends of PVA with MF and MUF were used as adhesives to bond wood joints. The shear strength of

Alireza Kaboorani; Bernard Riedl

2011-01-01

106

Regeneration of Cellulose Acetate Membranes.  

National Technical Information Service (NTIS)

Several simple methods for in situ one-step regeneration of both flux and salt-retention properties of service-deteriorated membranes have been developed. Membranes have been successfully regenerated using hot, 4% acetic acid, and a one-step cleaning meth...

P. A. Cantor, W. S. Higley, C. W. Saltonstall

1970-01-01

107

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

108

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

109

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

110

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

Microsoft Academic Search

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

Adeliani Almeida Campos; Dan Nathanson

1999-01-01

111

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

E-print Network

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

Fayer, Michael D.

112

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

E-print Network

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

Paris-Sud XI, Université de

113

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

E-print Network

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

Peppas, Nicholas A.

114

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

Microsoft Academic Search

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

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

1995-01-01

115

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

SciTech Connect

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

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

1993-11-05

116

Recovery of Agricultural Odors and Odorous Compounds from Polyvinyl Fluoride Film Bags  

PubMed Central

Accurate sampling methods are necessary when quantifying odor and volatile organic compound emissions at agricultural facilities. The commonly accepted methodology in the U.S. has been to collect odor samples in polyvinyl fluoride bags (PVF, brand name Tedlar®) and, subsequently, analyze with human panelists using dynamic triangular forced-choice olfactometry. The purpose of this research was to simultaneously quantify and compare recoveries of odor and odorous compounds from both commercial and homemade PVF sampling bags. A standard gas mixture consisting of p-cresol (40 ?g m?3) and seven volatile fatty acids: acetic (2,311 ?g m?3), propionic (15,800 ?g m?3), isobutyric (1,686 ?g m?3), butyric (1,049 ?g m?3), isovaleric (1,236 ?g m?3), valeric (643 ?g m?3), and hexanoic (2,158 ?g m?3) was placed in the PVF bags at times of 1 h, 1 d, 2 d, 3 d, and 7 d prior to compound and odor concentration analyses. Compound concentrations were quantified using sorbent tubes and gas chromatography/mass spectrometry. Odor concentration, intensity, and hedonic tone were measured using a panel of trained human subjects. Compound recoveries ranged from 2 to 40% after 1 h and 0 to 14% after 7 d. Between 1 h and 7 d, odor concentrations increased by 45% in commercial bags, and decreased by 39% in homemade bags. Minimal changes were observed in intensity and hedonic tone over the same time period. These results suggest that PVF bags can bias individual compound concentrations and odor as measured by dynamic triangular forced-choice olfactometry. PMID:22163671

Parker, David B.; Perschbacher-Buser, Zena L.; Cole, N. Andy; Koziel, Jacek A.

2010-01-01

117

40 CFR 414.40 - Applicability; description of the thermoplastic resins subcategory.  

...Resins Polyvinyl Acetate *Polyvinyl Acetate—PVC Copolymers *Polyvinyl Acetate Copolymers ...*Polyvinylidene-Vinyl Chloride Resins *PVC Copolymers, Acrylates (Latex) *PVC Copolymers, Ethylene-Vinyl Chloride...

2014-07-01

118

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2013 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2013-04-01

119

21 CFR 184.1721 - Sodium acetate.  

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2014-04-01

120

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2012 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2012-04-01

121

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2011 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2011-04-01

122

21 CFR 184.1721 - Sodium acetate.  

Code of Federal Regulations, 2010 CFR

...anhydrous or trihydrated form. It is produced synthetically by the neutralization of acetic acid with sodium carbonate or by treating calcium acetate with sodium sulfate and sodium bicarbonate. (b) The ingredient meets the...

2010-04-01

123

Concentrating aqueous acetate solutions with tertiary amines  

E-print Network

Water may be extracted from aqueous calcium acetate or sodium acetate solutions using low miscibility, low molecular weight tertiary amines, e.g. triethylamine (TEA) and N,N- dietliylmethylaniine (DEMA). This novel extraction technology...

Lee, Champion

2012-06-07

124

Identification of additives in poly(vinylacetate) artist's paints using PY-GC-MS.  

PubMed

Commercial poly(vinyl acetate) (PVAc) paint formulations for artists include a number of compounds in addition to the PVAc polymer and pigments to improve the physical and chemical properties of the resulting product. Among the most common additives are surfactants, coalescing agents, defoamers, freeze-thaw agents and thickeners. These products significantly influence the behaviour of the dried film. Nevertheless, they are usually difficult to detect with conventional analytical methods given their low concentration. In order to identify these additives, present in the dried film as minor components, an analytical method based on in situ thermally assisted pyrolysis-silylation gas chromatography-mass spectrometry (GC-MS) using hexamethyldisilazane as a derivatisation reagent is proposed. This method improves the conventional GC-MS analysis performed by direct pyrolysis and enables the simultaneous identification of the PVAc binding medium and the additives included by the manufacturer in the commercial paint. Five different commercial PVAc paints have been analysed, namely, armour green, burnt umber, oriental red, raw umber and white from Flashe. Internal plasticiser VeoVa consisting of C(10) fatty acids with highly branched chains has been recognised from the MS spectra. On the other hand, the differences found in the additive content of the studied paints, in particular the poly(ethylene glycol)-type surfactant, are in good agreement with their mechanical properties. PMID:20177664

Silva, Miguel F; Doménech-Carbó, Maria Teresa; Fuster-López, Laura; Mecklenburg, Marion F; Martin-Rey, Susana

2010-05-01

125

CORROSION OF LEAD SHIELDING IN NUCLEAR MATERIALS PACKAGES  

SciTech Connect

Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding that was induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species used in the construction of the packaging, followed by polyvinyl acetate (PVAc) glue. Fiberboard material, also used in the construction of the packaging induced corrosion to a much lesser extent than the PVAc glue and RTV sealant, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water. In light of these corrosion mechanisms, the lead shielding was sheathed in a stainless steel liner to mitigate against corrosion.

Subramanian, K; Kerry Dunn, K; Joseph Murphy, J

2008-07-18

126

CORROSION OF LEAD SHIELDING IN NUCLEAR MATERIALS PACKAGES  

SciTech Connect

Inspection of United States-Department of Energy (US-DOE) model 9975 nuclear materials shipping package revealed corrosion of the lead shielding induced by off-gas constituents from organic components in the package. Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of these organic materials. The results showed that the room temperature vulcanizing (RTV) sealant was the most corrosive organic species followed by the polyvinyl acetate (PVAc) glue. The fiberboard material induced corrosion to a much lesser extent than the PVAc glue and RTV, and only in the presence of condensed water. The results indicated faster corrosion at temperatures higher than ambient and with condensed water as expected. A corrosion rate of 0.05 mm/year measured for coupons exposed to the most aggressive conditions was recommended as a conservative estimate for use in package performance calculations.

Subramanian, K; Kerry Dunn, K

2007-11-16

127

Anodically generated cobalt(III) acetate as reagent for coulometric titrations in acetic acid  

Microsoft Academic Search

Summary Conditions for the anodic generation of cobalt(III) acetate with high current efficiency in non-aqueous solutions of potassium acetate in acetic acid have been investigated. The presence of water or acetic anhydride in the anolyte diminishes the amount of the generated oxidant. The stability of the generated cobalt(III) acetate solution is decreased in the presence of water and at elevated

T. J. Pastor; I. ?iri?

1985-01-01

128

Evaluation of a Polyvinyl Toluene Neutron Counter Array  

SciTech Connect

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

Robert Hayes

2008-03-01

129

Evaluation of vascular grafts based on polyvinyl alcohol cryogels.  

PubMed

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

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

2014-09-01

130

Vitrification of Polyvinyl Chloride Waste from Korean Nuclear Power Plants  

SciTech Connect

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

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

2000-02-15

131

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

132

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

133

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

134

Effect of polyvinyl alcohol hydrogel as a biocarrier on volatile fatty acids production of a two-stage thermophilic anaerobic membrane bioreactor.  

PubMed

This work studied the effect of polyvinyl alcohol hydrogel (PVA-gel) beads, as an effective biocarrier for volatile fatty acid (VFA) production in hydrolytic reactor of a two-stage thermophilic anaerobic membrane bioreactor (TAnMBR). The two-stage TAnMBR, treating synthetic high strength particulate wastewater with influent chemical oxygen demand (COD) [16.4±0.8 g/L], was operated at 55 °C. Under steady state conditions, the reactor was operated at an organic loading rate of 8.2±0.4 kg COD/m(3) d. Operational performance of the system was monitored by assessing VFA composition and quantity, methane production and COD removal efficiency. Increment of VFA production was observed with PVA-gel addition. Hydrolytic effluent contained large amount of acetic acid and n-butyric acid. However, increase in VFA production adversely affected the methanogenic reactor performance due to lack of methanogenic archaea. PMID:24803272

Chaikasem, Supawat; Abeynayaka, Amila; Visvanathan, Chettiyappan

2014-09-01

135

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

136

Molecular Structure of Ethyl acetate  

NSDL National Science Digital Library

Ethyl acetate is a colorless, volatile liquid with a mild and fragrant odor. It is used as solvent in chemistry laboratories but can also be found in many household products such as paints, coatings, and adhesives. The compound is also used in some extraction processes such as decaffeination or purification of antibiotics. It is present in both nail polish and removers. Some synthetic fruit essences may contain this and other esters. Etymologists like to use this solvent for insect collecting as the vapor kill the insect quickly and keep it soft for mounting.

2006-03-08

137

Utilizing Matrix-Filler Interactions in the Design of Stimuli-Responsive, Mechanically-Adaptive Electrospun Composites  

NASA Astrophysics Data System (ADS)

A new class of all-organic, stimuli-responsive and mechanically-adaptive electrospun nanocomposites, which have the ability to alter their stiffness upon hydration, were developed. These materials were fabricated by incorporating an electrospun mat of poly(vinyl alcohol) (PVA) as the filler in a polymeric matrix consisting of either poly(vinyl acetate) (PVAc) or ethylene oxide-epicholorohydrin copolymer (EO-EPI). The incorporation of high stiffness, high aspect ratio PVA filler mat significantly enhanced the tensile storage modulus of EO-EPI based composites, while modulus enhancement was only noticed above the glass transition for PVAc-based composites. Composite materials based on a rubbery EO-EPI host polymer and PVA filler exhibit an irreversible reduction by a factor of 12 of the tensile modulus upon hydration. In contrast, composites comprised of PVAc show a reversible reduction of modulus by a factor of 280 upon water uptake. The mechanical morphing of the electrospun composites is the result of the filler crystallinity, and matrix-filler interactions facilitated by the surface hydroxyl groups of the PVA filler. The choice of polymer matrix and electrospun nanofiber fillers allow control of matrix-filler interactions in a new series of all-organic composites to achieve desired stimuli-responsiveness and mechanical-adaptability upon exposure to various stimuli.

Wanasekara, Nandula; Stone, David; Wnek, Gary; Korley, Lashanda

2013-03-01

138

Soluplus graft copolymer: potential novel carrier polymer in electrospinning of nanofibrous drug delivery systems for wound therapy.  

PubMed

Electrospinning is an effective method in preparing polymeric nanofibrous drug delivery systems (DDSs) for topical wound healing and skin burn therapy applications. The aim of the present study was to investigate a new synthetic graft copolymer (Soluplus) as a hydrophilic carrier polymer in electrospinning of nanofibrous DDSs. Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG)) was applied in the nonwoven nanomats loaded with piroxicam (PRX) as a poorly water-soluble drug. Raman spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and scanning electron microscopy (SEM) were used in the physical characterization of nanofibrous DDSs. According to the SEM results, the drug-loaded PCL-PVAc-PEG nanofibers were circular in cross-section with an average diameter ranging from 500?nm up to 2? µm. Electrospinning stabilized the amorphous state of PRX. In addition, consistent and sustained-release profile was achieved with the present nanofibrous DDSs at the physiologically relevant temperature and pH applicable in wound healing therapy. In conclusion, electrospinning can be used to prepare nanofibrous DDSs of PCL-PVAc-PEG graft copolymer (Soluplus) and to stabilize the amorphous state of a poorly water-soluble PRX. The use of this synthetic graft copolymer can open new options to formulate nanofibrous DDSs for wound healing. PMID:24575414

Paaver, Urve; Tamm, Ingrid; Laidmäe, Ivo; Lust, Andres; Kirsimäe, Kalle; Veski, Peep; Kogermann, Karin; Heinämäki, Jyrki

2014-01-01

139

Soluplus Graft Copolymer: Potential Novel Carrier Polymer in Electrospinning of Nanofibrous Drug Delivery Systems for Wound Therapy  

PubMed Central

Electrospinning is an effective method in preparing polymeric nanofibrous drug delivery systems (DDSs) for topical wound healing and skin burn therapy applications. The aim of the present study was to investigate a new synthetic graft copolymer (Soluplus) as a hydrophilic carrier polymer in electrospinning of nanofibrous DDSs. Soluplus (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (PCL-PVAc-PEG)) was applied in the nonwoven nanomats loaded with piroxicam (PRX) as a poorly water-soluble drug. Raman spectroscopy, X-ray powder diffraction, differential scanning calorimetry, and scanning electron microscopy (SEM) were used in the physical characterization of nanofibrous DDSs. According to the SEM results, the drug-loaded PCL-PVAc-PEG nanofibers were circular in cross-section with an average diameter ranging from 500?nm up to 2?µm. Electrospinning stabilized the amorphous state of PRX. In addition, consistent and sustained-release profile was achieved with the present nanofibrous DDSs at the physiologically relevant temperature and pH applicable in wound healing therapy. In conclusion, electrospinning can be used to prepare nanofibrous DDSs of PCL-PVAc-PEG graft copolymer (Soluplus) and to stabilize the amorphous state of a poorly water-soluble PRX. The use of this synthetic graft copolymer can open new options to formulate nanofibrous DDSs for wound healing. PMID:24575414

Tamm, Ingrid; Laidmae, Ivo; Lust, Andres; Kirsimae, Kalle

2014-01-01

140

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

E-print Network

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

Sample, Caitlin (Caitlin Sarah)

2014-01-01

141

Polymer-Titanium hybrids obtained by radical polymerization and Sol-Gel process  

Microsoft Academic Search

The possibility to prepare hybrids made by poly(vinyl acetate) (PVAc), poly(methyl methacrylate) (PMMA) and\\/or poly(ethyl\\u000a acrylate) (PEtA) with TiO2 was studied. The processes of polymer formation-radical polymerization and sol-gel process for inorganic network —were achieved\\u000a simultaneously. Due to a high reactivity of titanium isopropoxide (TIP) in the sol-gel process, a complexant comonomer, allyl\\u000a acetoacetate (AlAcAc), was used. Covalent bonds between

Dan Donescu; Sever Serban; Kristiana Gosa; Cristian Petcu

2005-01-01

142

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

143

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

Microsoft Academic Search

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

Jian Xu; Zhen-Liang Xu

2002-01-01

144

Metabolism of steroid acetates by Streptomyces albus.  

PubMed

Fermentation of 16-dehydropregnenolone acetate (1a) with Streptomyces albus yielded 16-dehydropregnenolone (1b) and 16-dehydroprogesterone (IIa). Similar incubation of pregnenolone acetate (Ic) with the strain afforded pregnenolone (Id), progesterone (IIb) and 20 alpha-hydroxy progesterone (IIc) while dehydroepiandrosterone acetate (IIIa) under the conditions was converted to dehydroepiandrosterone (IIIb), androstenedione (IVa) and testosterone (IVc). The strain was also capable of converting testosterone acetate (IVb) having the 17-acetoxy function in the 5-membered D-ring to testosterone (IVc) and androstenedione (IVa). All the products were identified by the application of various chemical and spectrometric techniques. PMID:6708550

Mukherjee, A; Mahato, S B

1984-03-01

145

Positron scattering from vinyl acetate  

NASA Astrophysics Data System (ADS)

Using a Beer-Lambert attenuation approach, we report measured total cross sections (TCSs) for positron scattering from vinyl acetate (C4H6O2) in the incident positron energy range 0.15-50 eV. In addition, we also report an independent atom model with screening corrected additivity rule computation results for the TCSs, differential and integral elastic cross sections, the positronium formation cross section and inelastic integral cross sections. The energy range of these calculations is 1-1000 eV. While there is a reasonable qualitative correspondence between measurement and calculation for the TCSs, in terms of the energy dependence of those cross sections, the theory was found to be a factor of ˜2 larger in magnitude at the lower energies, even after the measured data were corrected for the forward angle scattering effect.

Chiari, L.; Zecca, A.; Blanco, F.; García, G.; Brunger, M. J.

2014-09-01

146

Oxygen17 and proton nuclear magnetic resonance studies on acetic acid exchange processes of the chloride, nitrate, and acetate of nickel(II) in acetic acid  

Microsoft Academic Search

The exchange rates of acetic acid coordinating to nickel(II) chloride, nickel(II) nitrate, and nickel(II) acetate in neat acetic acid and acetic acid\\/dichloromethane-d2 mixtures were measured by the oxygen-17 and proton NMR line-broadening methods. The activation parameters for the acetic acid exchange on these nickel(II) salts were independent of the concentration of acetic acid (HOAc) in the mixed solvents. The first-order

A. Hioki; S. Funahashi; M. Tanaka

1985-01-01

147

Compression properties of polyvinyl alcohol--bacterial cellulose nanocomposite.  

PubMed

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

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

2009-08-01

148

Oil reclamation from waste plastics including polyvinyl chloride  

SciTech Connect

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

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

1995-12-31

149

Dielectric breakdown during Cs+ sputtering of polyvinyl chloride  

NASA Astrophysics Data System (ADS)

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

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

2014-02-01

150

Modeling of solute sorption by polyvinyl chloride plastic infusion bags.  

PubMed

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

Jenke, D R

1993-11-01

151

Biodegradable Plastics Based on Cellulose Acetate  

Microsoft Academic Search

It is generally known that secondary cellulose acetate (with 53 to 56% acetyl groups) is suitable for thermoplastic processing. With appropriate plasticizers a plastic material is obtained which excels in transparency and pleasant texture, and it is therefore often used for tool handles, combs, spectacle frames, and the like. In principle, cellulose acetate with such a degree of substitution is

Alexander Ach

1993-01-01

152

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2012 CFR

21 Food and Drugs 6 2012-04-01...2012-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2012-04-01

153

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 6 2013-04-01...2013-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2013-04-01

154

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2011 CFR

21 Food and Drugs 6 2011-04-01...2011-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2011-04-01

155

21 CFR 582.1005 - Acetic acid.  

Code of Federal Regulations, 2010 CFR

21 Food and Drugs 6 2010-04-01...2010-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2010-04-01

156

21 CFR 582.1005 - Acetic acid.  

21 Food and Drugs 6 2014-04-01...2014-04-01 false Acetic acid. 582.1005 Section 582.1005 Food and Drugs FOOD AND DRUG ADMINISTRATION...CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED... § 582.1005 Acetic acid. (a) Product....

2014-04-01

157

Manufacturing Ethyl Acetate From Fermentation Ethanol  

NASA Technical Reports Server (NTRS)

Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

Rohatgi, Naresh K.; Ingham, John D.

1991-01-01

158

Mercaptobenzothiazole-on-gold organic phase biosensor systems: 1. Enhanced organosphosphate pesticide determination.  

PubMed

This paper reports the construction of the gold/mercaptobenzothiazole/polyaniline/acetylcholinesterase/polyvinylacetate (Au/ MBT/PANI/AChE/PVAc) thick-film biosensor for the determination of certain organophosphate pesticide solutions in selected aqueous organic solvent solutions. The Au/MBT/PANI/AChE/PVAc electrocatalytic biosensor device was constructed by encapsulating acetylcholinesterase (AChE) enzyme in the PANI polymer composite, followed by the coating of poly(vinyl acetate) (PVAc) on top to secure the biosensor film from disintegration in the organic solvents evaluated. The electroactive substrate called acetylthiocholine (ATCh) was employed to provide the movement of electrons in the amperometric biosensor. The voltammetric results have shown that the current shifts more anodically as the Au/MBT/PANI/AChE/PVAc biosensor responded to successive acetylthiocholine (ATCh) substrate addition under anaerobic conditions in 0.1 M phosphate buffer, KCl (pH 7.2) solution and aqueous organic solvent solutions. For the Au/MBT/PANI/AChE/PVAc biosensor, various performance and stability parameters were evaluated. These factors include the optimal enzyme loading, effect of pH, long-term stability of the biosensor, temperature stability of the biosensor, the effect of polar organic solvents, and the effect of non-polar organic solvents on the amperometric behavior of the biosensor. The biosensor was then applied to detect a series of 5 organophosphorous pesticides in aqueous organic solvents and the pesticides studied were parathion-methyl, malathion and chlorpyrifos. The results obtained have shown that the detection limit values for the individual pesticides were 1.332 nM (parathion-methyl), 0.189 nM (malathion), 0.018 nM (chlorpyrifos). PMID:19130375

Somerset, V; Baker, P; Iwuoha, E

2009-02-01

159

Enhanced Glucose Sensor Linearity Using Poly(Vinyl Alcohol) Hydrogels  

PubMed Central

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

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

2009-01-01

160

21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.  

...2014-04-01 2014-04-01 false Ethyl alcohol containing ethyl acetate. 584.200...Affirmed as GRAS § 584.200 Ethyl alcohol containing ethyl acetate. The feed additive ethyl alcohol containing ethyl acetate meets the...

2014-04-01

161

Correlation between acetic acid resistance and characteristics of PQQ-dependent ADH in acetic acid bacteria.  

PubMed

In this study, we compared the growth properties and molecular characteristics of pyrroloquinoline quinone (PQQ)-dependent alcohol dehydrogenase (ADH) among highly acetic acid-resistant strains of acetic acid bacteria. Gluconacetobacter europaeus exhibited the highest resistance to acetic acid (10%), whereas Gluconacetobacter intermedius and Acetobacter pasteurianus resisted up to 6% of acetic acid. In media with different concentrations of acetic acid, the maximal acetic acid production rate of Ga. europaeus slowly increased, but specific growth rates decreased concomitant with increased concentration of acetic acid in medium. The lag phase of A. pasteurianus was twice and four times longer in comparison to the lag phases of Ga. europaeus and Ga. intermedius, respectively. PQQ-dependent ADH activity was twice as high in Ga. europaeus and Ga. intermedius as in A. pasteurinus. The purified enzymes showed almost the same specific activity to each other, but in the presence of acetic acid, the enzyme activity decreased faster in A. pasteurianus and Ga. intermedius than in Ga. europaeus. These results suggest that high ADH activity in the Ga. europaeus cells and high acetic acid stability of the purified enzyme represent two of the unique features that enable this species to grow and stay metabolically active at extremely high concentrations of acetic acid. PMID:16133326

Trcek, Janja; Toyama, Hirohide; Czuba, Jerzy; Misiewicz, Anna; Matsushita, Kazunobu

2006-04-01

162

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

PubMed

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

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

1990-01-01

163

Acetic acid fermentation of acetobacter pasteurianus: relationship between acetic acid resistance and pellicle polysaccharide formation.  

PubMed

Acetobacter pasteurianus strains IFO3283, SKU1108, and MSU10 were grown under acetic acid fermentation conditions, and their growth behavior was examined together with their capacity for acetic acid resistance and pellicle formation. In the fermentation process, the cells became aggregated and covered by amorphous materials in the late-log and stationary phases, but dispersed again in the second growth phase (due to overoxidation). The morphological change in the cells was accompanied by changes in sugar contents, which might be related to pellicle polysaccharide formation. To determine the relationship between pellicle formation and acetic acid resistance, a pellicle-forming R strain and a non-forming S strain were isolated, and their fermentation ability and acetic acid diffusion activity were compared. The results suggest that pellicle formation is directly related to acetic acid resistance ability, and thus is important to acetic acid fermentation in these A. pasteurianus strains. PMID:20699583

Kanchanarach, Watchara; Theeragool, Gunjana; Inoue, Taketo; Yakushi, Toshiharu; Adachi, Osao; Matsushita, Kazunobu

2010-01-01

164

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.

165

Fluorescence quenching of etilefrine by acetate anion  

NASA Astrophysics Data System (ADS)

Acid dissociation in the excited state of antihypotensor drug etilefrine [2-(ethylamino1-3-hydroxyphenyl)ethanol] is studied. Fluorescence of etilefrine decreases at pH<7 and is related to phenolic group dissociation. However, intensity of etilefrine fluorescence diminishes as the concentration of the acetate anion increases at pH>7. Analyses of the absorption and fluorescence spectra of aqueous solutions of etilefrine in the presence of acetate anions have been made. Considering the existence of an equilibrium in the excited state the values of 3.47×10 -9 and 0.216×10 -9 M -1 s -1 have been obtained for the rate constants for direct and inverse reactions, respectively. Moreover, the lifetime ( ?0'=0.58×10 -9 s) and quantum yield (0.01) of non-protonated etilefrine have been determined. Our results seem to support the existence of a dynamic quenching process based on a proton transfer mechanism induced by acetate anions. This process could represent a serious inconvenience in analytical fluorimetric techniques taking into account that the acetic acid/acetate pair is commonly used as a buffer. Additional fluorescence quenching by H + ions could be involved in acid aqueous mediums. At high concentrations of acetic acid, a value of 2.98×10 -9 M -1 s -1 for the bimolecular constant for the quenching by H + has been calculated.

Quintero Osso, B.; Carazo Rodríguez, F. M.; Morales Domingo, J. J.; Cabeza González, M. C.; Thomas Gómez, J.

1999-02-01

166

Acetate limitation and nitrite accumulation during denitrification  

SciTech Connect

Nitrite accumulated in denitrifying activated sludge mixed liquor when the carbon and electron source, acetate, was limited. If acetate was added to obtain a carbon-to-nitrogen (C:N) ratio in the range of 2:1 to 3:1, nitrate was completely consumed at the same rate with no nitrite accumulation, indicating that nitrate concentration controlled the respiration rate as long as sufficient substrate was present. However, when acetate was reduced to a C:N ratio of 1:1, while nitrate continued to be consumed, > 50% of the initial nitrate-nitrogen accumulated as nitrite and 29% persisted as nitrite throughout an endogenous denitrification period of 8--9 h. While nitrite accumulated during acetate-limited denitrification, the specific nitrate reduction rate increased significantly compared with the rate when excess acetate was provided as follows: 0.034 mg-NO{sub 3}-N/mg-mixed liquid volatile suspended solids/h versus 0.023 mg-NO{sub 3}-N/mg-mixed liquid volatile suspended solids/h, respective. This may be explained by nitrate respiration out-competing nitrite respiration for limited acetate electrons. Complete restoration of balanced denitrification and elimination of nitrite accumulation during denitrification required several weeks after the C:N ratio was increased back to 2:1.

Oh, J. [Pohang Univ. of Science and Technology (Korea, Republic of). School of Environmental Engineering] [Pohang Univ. of Science and Technology (Korea, Republic of). School of Environmental Engineering; Silverstein, J. [Univ. of Colorado, Boulder, CO (United States)] [Univ. of Colorado, Boulder, CO (United States)

1999-03-01

167

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

NASA Astrophysics Data System (ADS)

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

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

1995-07-01

168

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

Microsoft Academic Search

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

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

2002-01-01

169

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

Microsoft Academic Search

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

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

2006-01-01

170

Identification method of synthetic polymers by high-performance liquid chromatography  

SciTech Connect

Polyvinyl chloride (PVC), polyvinyl acetate (PVAc), and their copolymers and blends, polystyrene, poly(methyl, ethyl, and butyl) acrylates and methacrylates were dissolved in tetrahydrofuran (THF), respectively, and the solutions were injected into a column of silica gel having a pore diameter of 30 A and eluted with the mobile phases of THF, chloroform, ethyl acetate, methanol, methylethylketone, acetonitrile and 1,2-dichloroethane (DCE). Some polymers eluted from the column and the rest were retained in the column. The identification of the polymers was not based on the difference in the retention volumes of the polymers, but the elution of the polymers from or the retention in the column were a measure of the identification. This technique was termed as On-Off Elution Method'. Two retention mechanisms were proposed: hydrogen bonding between silica gel and the sample polymers, and the precipitation of polymers in the column. In case of the former, some polymers were retained in the column even though a good solvent to the polymers was used as the mobile phase. When poor solvents to the polymers were used as the mobile phases, the polymers were precipitated in the column, except PVC with DCE. The physical blend of PVC and PVAc could be discriminated from the copolymer having the same composition by this procedure.

Mori, Sadao (Mie Univ., Tsu (Japan))

1993-01-01

171

Acetate transport and utilization in the rat brain.  

PubMed

Acetate, a glial-specific substrate, is an attractive alternative to glucose for the study of neuronal-glial interactions. The present study investigates the kinetics of acetate uptake and utilization in the rat brain in vivo during infusion of [2-13C]acetate using NMR spectroscopy. When plasma acetate concentration was increased, the rate of brain acetate utilization (CMR(ace)) increased progressively and reached close to saturation for plasma acetate concentration > 2-3 mM, whereas brain acetate concentration continued to increase. The Michaelis-Menten constant for brain acetate utilization (K(M)(util) = 0.01 +/- 0.14 mM) was much smaller than for acetate transport through the blood-brain barrier (BBB) (K(M)(t) = 4.18 +/- 0.83 mM). The maximum transport capacity of acetate through the BBB (V(max)(t) = 0.96 +/- 0.18 micromol/g/min) was nearly twofold higher than the maximum rate of brain acetate utilization (V(max)(util) = 0.50 +/- 0.08 micromol/g/min). We conclude that, under our experimental conditions, brain acetate utilization is saturated when plasma acetate concentrations increase above 2-3 mM. At such high plasma acetate concentration, the rate-limiting step for glial acetate metabolism is not the BBB, but occurs after entry of acetate into the brain. PMID:19393008

Deelchand, Dinesh K; Shestov, Alexander A; Koski, Dee M; U?urbil, Kâmil; Henry, Pierre-Gilles

2009-05-01

172

Acetate and hypercalciuria during total parenteral nutrition13  

Microsoft Academic Search

Hypercalciuria and negative calcium balance are complications oftotal par- enteral nutrition (TPN). Because metabolism ofthe TPN formula generates an acid load that can induce hypercalciuria, we evaluated the effect ofsupplementing the formula with acetate. In a randomized crossover study six patients on continuous and six on cyclic TPN received no added acetate or 160 mmol acetate\\/d replacing 160 mmol chloride\\/d

Charles H Berkelhammer; Richard J Wood; Michael D Sitrin

173

Acetate reduces microglia inflammatory signaling in vitro  

PubMed Central

Acetate supplementation increases brain acetyl-CoA and histone acetylation and reduces lipopolysaccharide (LPS)-induced neuroglial activation and interleukin (IL)-1? expression in vivo. To determine how acetate imparts these properties, we tested the hypothesis that acetate metabolism reduces inflammatory signaling in microglia. To test this, we measured the effect acetate treatment had on cytokine expression, mitogen-activated protein kinase (MAPK) signaling, histone H3 at lysine 9 acetylation, and alterations of nuclear factor-kappa B (NF-?B) in primary and BV-2 cultured microglia. We found that treatment induced H3K9 hyperacetylation and reversed LPS-induced H3K9 hypoacetylation similar to that found in vivo. LPS also increased IL-1?, IL-6 and tumor necrosis factor-alpha (TNF-?) mRNA and protein, while treatment returned the protein to control levels and only partially attenuated IL-6 mRNA. In contrast, treatment increased mRNA levels of transforming-growth factor-?1 (TGF-?1) and both IL-4 mRNA and protein. LPS increased p38 MAPK and JNK phosphorylation at 4 and 2–4 hr respectively, while treatment reduced p38 MAPK and JNK phosphorylation only at 2 hr. In addition, treatment reversed the LPS-induced elevation of NF-?B p65 protein and phosphorylation at serine 468 and induced acetylation at lysine 310. These data suggest that acetate metabolism reduces inflammatory signaling and alters histone and non-histone protein acetylation. PMID:22924711

Soliman, Mahmoud L.; Puig, Kendra L.; Combs, Colin K.; Rosenberger, Thad A.

2012-01-01

174

The behaviour of tungsten electrodes in a mixture of acetic acid and acetic anhydride  

Microsoft Academic Search

Summary Tungsten electrodes have advantageously been used for potentiometric end-point detection in perchloric acid titration of bases in a mixture of acetic acid and acetic anhydride. They have also given good results in biamperometric detection of the equivalence point in continuous coulometric titration of small quantities of bases and acids in the same solvent. Tungsten electrodes in the presence of

Tibor J. Pastor; Vilim J. Vajgand

1976-01-01

175

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

Microsoft Academic Search

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

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

1998-01-01

176

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

Microsoft Academic Search

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

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

2009-01-01

177

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

Microsoft Academic Search

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

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

2010-01-01

178

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

179

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

Microsoft Academic Search

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

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

2004-01-01

180

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

SciTech Connect

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

Oji, L.N.

1998-11-25

181

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

E-print Network

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

182

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

National Technical Information Service (NTIS)

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

C. Arnold, A. Leo, M. Tarjani

1988-01-01

183

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

NASA Astrophysics Data System (ADS)

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

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

1995-03-01

184

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

PubMed

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

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

2012-12-01

185

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

Microsoft Academic Search

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

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

2003-01-01

186

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

Microsoft Academic Search

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

Nicolas M Orsi; Henry J Leese

2004-01-01

187

40 CFR 61.64 - Emission standard for polyvinyl chloride plants.  

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

2014-07-01

188

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

189

CORROSION OF LEAD SHIELDING IN MODEL 9975 PACKAGE  

SciTech Connect

Experiments were performed to determine the corrosion rate of lead when exposed to off-gas or degradation products of organic materials used in the model 9975 package.[1] The experiments were completed within the framework of a parametric test matrix with variables of organic configuration, temperature, humidity and the effect of durations of exposure on the corrosion of lead in the 9975 package. The room temperature vulcanizing (RTV) sealant was the most corrosive organic species in the testing, followed by the polyvinyl acetate (PVAc) glue. The Celotex{copyright} material uniquely induced measurable corrosion only in situations with condensed water, and to a much lesser extent than the PVAc glue and RTV. The coupons exhibited faster corrosion at higher temperatures than at room temperatures. There was a particularly pronounced effect of condensed water as the coupons exposed in the cells with condensed water exhibited much higher corrosion rates. In the 9975 package, the PVAc glue was determined to be the most aggressive due to it's proximity in the design. The condition considered most representative of the package conditions is that of the coupon exposed to the Celotex{copyright}/glue organic exposed in the ambient humidity conditions. The corrosion rate of 2 mpy measured in the laboratory experiments for this condition is considered to be a bounding condition to the 9975 package conditions when the laboratory results are extrapolated to actual package conditions, and is recommended as a conservative estimate for package performance calculations.

Subramanian, K

2006-03-15

190

A theoretical study of structure-solubility correlations of carbon dioxide in polymers containing ether and carbonyl groups.  

PubMed

This work involves a theoretical study to investigate the effects of the structure on CO(2) sorption in polymers, where poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO), poly(vinyl acetate) (PVAc), poly(ethylene carbonate) (PEC) and poly(propylene carbonate) (PPC) were examined. In the theoretical approach, the multi-site semiflexible chain model and the renormalized technique of electrostatic potentials were incorporated into the polymer reference interaction site model (PRISM). To test the theory, molecular dynamic simulations were performed using the TraPPE-UA force field. The theoretically calculated reduced X-ray scattering intensities and intermolecular correlation functions of these five polymers are found to be in qualitative agreement with the corresponding molecular simulation data. The theory was then employed to investigate the distribution functions between CO(2) and different sites of the polymers with consideration of the Lennard-Jones, potential of mean force, and columbic contributions. Based on the detailed structure characteristics of CO(2) in contact with different groups, the CO(2) coordination molecular numbers were obtained and their sorption intensities analyzed. Finally, the sorption isotherms of CO(2) in these five polymers were calculated. The results for PEO, PPO and PVAc are close to the available experimental curves, and the trend of CO(2) solubility is PPC > PEC > PVAc ~ PPO > PEO. PMID:22025210

Xu, Mengjin; Chen, Jian; Zhang, Chen; Du, Zhongjie; Mi, Jianguo

2011-12-21

191

Electrospinning processed nanofibrous TiO2 membranes for photovoltaic applications  

NASA Astrophysics Data System (ADS)

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO2 membranes as electrode materials. A thin TiO2 film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF4 aqueous solution to reduce the electron back-transfer from FTO to the electrolyte. The composite polyvinyl acetate (PVac)/titania nanofibrous membranes can be deposited on the pre-deposited thin TiO2 film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO2 membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO2 membranes was carried out with a ruthenium (II) complex, cis-dithiocyanate-N,N'-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid) ruthenium (II) dihydrate. The results indicated that the photocurrent and conversion efficiency of electrodes can be increased with the addition of the pre-deposited TiO2 film and the adhesion treatment using DMF. Additionally, the dye loading, photocurrent, and efficiency of the electrodes were gradually increased by increasing the average thickness of the nanofibrous TiO2 membranes. The efficiency of the fibrous TiO2 photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%.

Onozuka, Katsuhiro; Ding, Bin; Tsuge, Yosuke; Naka, Takayuki; Yamazaki, Michiyo; Sugi, Shinichiro; Ohno, Shingo; Yoshikawa, Masato; Shiratori, Seimei

2006-02-01

192

Polymer-grafted silica: A screening system for polymeric adsorption resin development  

SciTech Connect

A screening-level methodology was developed for the evaluation of solute affinity for polymers that are candidate sorption resins. In this approach novel grafted polymer-silica resins were synthesized to produce poly(vinylpyrrolidone)-silica (PVP-Si) and poly(vinyl acetate)-silica (PVAc-Si) resins. The polymer-silica resins along with a number of commercially available polymer resins were used to evaluate the aqueous-phase adsorption of phenol, tetrachloroethene (PCE), trichloroethene (TCE), and chloroform. The polymer-grafted silicas were able to selectively remove pollutants from water with a covalently bonded polymer layer that has a high affinity for the target pollutant. The PVAc-silica resin had a sorption capacity for TCE and CHCl[sub 3] as high as commercial poly(styrene) resin XAD-4; the PVP-Si resin had a sorption capacity for phenol higher than a commercial poly-(vinylpyridine) resin (Reillex 425). PCE adsorption onto the PVAc-silica was comparable to the commercial poly(methacrylate) and poly(vinylpyridine) resins but less than the poly(styrene) resin. The results show that the Hildebrand solubility parameter along with the dipole moment of the polymer functional groups can be used for an initial screening-level assessment of polymer-solute affinity.

Browne, T.E.; Cohen, Y. (Univ. of California, Los Angeles (United States))

1993-04-01

193

Acetic acid mediated interactions between alumina surfaces  

NASA Astrophysics Data System (ADS)

Low-molecular-weight organic acids have been known to modify colloidal stability of alumina-based suspensions. We investigated interaction forces between alumina surfaces mediated by acetic acid which is one of the simplest organic acids. Forces between alumina surfaces were measured using the colloid-probe method of atomic force microscope (AFM). Repulsive forces attributed to steric repulsion due to adsorbed molecules and electrostatic repulsion dominated the interaction. Results of rheological characterization of the alumina slurry containing acetic acid supported the finding.

Sato, Kimiyasu; Y?lmaz, Hüseyin; Ijuin, Atsuko; Hotta, Yuji; Watari, Koji

2012-02-01

194

Organic/inorganic nanocomposites, methods of making, and uses as a permeable reactive barrier  

DOEpatents

Nanocomposite materials having a composition including an inorganic constituent, a preformed organic polymer constituent, and a metal ion sequestration constituent are disclosed. The nanocomposites are characterized by being single phase, substantially homogeneous materials wherein the preformed polymer constituent and the inorganic constituent form an interpenetrating network with each other. The inorganic constituent may be an inorganic oxide, such as silicon dioxide, formed by the in situ catalyzed condensation of an inorganic precursor in the presence of the solvated polymer and metal ion sequestration constituent. The polymer constituent may be any hydrophilic polymer capable of forming a type I nanocomposite such as, polyacrylonitrile (PAN), polyethyleneoxide (PEO), polyethylene glycol (PEG), polyvinyl acetate (PVAc), polyvinyl alcohol (PVA), and combinations thereof. Nanocomposite materials of the present invention may be used as permeable reactive barriers (PRBs) to remediate contaminated groundwater. Methods for making nanocomposite materials, PRB systems, and methods of treating groundwater are also disclosed.

Harrup, Mason K. (Idaho Falls, ID); Stewart, Frederick F. (Idaho Falls, ID)

2007-05-15

195

Immunotoxicity of Trenbolone Acetate in Japanese Quail  

Microsoft Academic Search

Trenbolone acetate is a synthetic androgen that is currently used as a growth promoter in many meat-exporting countries. Despite industry laboratories classifying trenbolone as nonteratogenic, data showed that embryonic exposure to this androgenic chemical altered development of the immune system in Japanese quail. Trenbolone is lipophilic, persistent, and released into the environment in manure used as soil fertilizer. This is

Michael James Quinn; Moira McKernan; Emma T. Lavoie; Mary Ann Ottinger

2006-01-01

196

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2013 CFR

21 Food and Drugs 1 2013-04-01 2013-04-01...acetate. 73.2396 Section 73.2396 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT...than 4.7 and not more than 5.8. Arsenic (as As), not more than 3 parts...

2013-04-01

197

Drying Cellulose Acetate Reverse Osmosis Membranes.  

National Technical Information Service (NTIS)

The membranes currently used in reverse osmosis for desalination are made of cellulose acetate. Modified membranes, because they contain a large number of pores, contain large quantities of water, 60 to 70 wt. %. If this water is allowed to evaporate unde...

K. D. Vos, F. O. Burris

1967-01-01

198

Heat Bonding of Irradiated Ethylene Vinyl Acetate  

NASA Technical Reports Server (NTRS)

Reliable method now available for joining parts of this difficult-tobond material. Heating fixture encircles ethylene vinyl acetate multiplesocket part, providing heat to it and to tubes inserted in it. Fixtures specially designed to match parts to be bonded. Tube-and-socket bonds made with this technique subjected to tensile tests. Bond strengths of 50 percent that of base material obtained consistently.

Slack, D. H.

1986-01-01

199

Process for the preparation of vinyl acetate  

DOEpatents

This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85 and 200 C and removing the reaction products from the contact zone.

Tustin, G.C.; Zoeller, J.R.; Depew, L.S.

1998-02-17

200

Strengths of the Chloro-acetic Acids  

Microsoft Academic Search

IT is well known that the introduction of chlorine atoms into acetic acid causes a rapid rise of dissociation constant (see ). If changes in the value of K are taken as a measure of the effect of the chlorine atoms, it would appear that the second chlorine atom has a greater effect than the first, and the third a

John Shorter; F. J. Stubbs

1949-01-01

201

Process for the preparation of vinyl acetate  

DOEpatents

This invention pertains to the preparation of vinyl acetate by contacting within a contact zone a mixture of ketene and acetaldehyde with an acid catalyst at about one bar pressure and between about 85.degree. and 200.degree. C. and removing the reaction products from the contact zone.

Tustin, Gerald Charles (Kingsport, TN); Zoeller, Joseph Robert (Kingsport, TN); Depew, Leslie Sharon (Kingsport, TN)

1998-01-01

202

Corrosion of stainless steel during acetate production  

SciTech Connect

Corrosion of types 304, 304L, 316, and 316L stainless steel (SS) during the esterification of acetic acid and alcohol or glycol ether was investigated. The catalyst for this reaction, sulfuric acid or para-toluene sulfonic acid (PTSA), was shown to cause more corrosion on reactor equipment than CH{sub 3}COOH under the process conditions commonly practiced in industry. The corrosive action of the catalyst occurred only in the presence of water. Thus, for the batch processes, corrosion occurred mostly during the initial stage of esterification, where water produced by the reaction created an aqueous environment. After water was distilled off, the corrosion rate declined to a negligible value. The corrosion inhibitor copper sulfate, often used in industrial acetate processes, was found to work well for a low-temperature process (< 95 C) such as in production of butyl acetate, but it accelerated corrosion in the glycol ether acetate processes where temperatures were > 108 C. Process conditions that imparted low corrosion rates were determined.

Qi, J.S.; Lester, G.C. [Occidental Chemical Corp. Technology Center, Grand Island, NY (United States)

1996-07-01

203

Fermentative biohydrogen production from lactate and acetate.  

PubMed

In this study, a continuous-flow stirred tank reactor (CSTR) fed with lactate and acetate was operated to enrich hydrogen-producing bacteria. By varying the influent substrate concentrations and hydraulic retention times (HRT), the volumetric loading rate (VLR) of 55.64 kg-COD/m(3)/day seemed to be optimum for this enriched culture for fermentative hydrogen production from lactate and acetate. The results of batch experiments confirmed that the enriched culture tended to fulfill the e(-) equiv requirement for cell growth at a lower VLR condition (21.77 kg-COD/m(3)/day), while it could largely distribute the e(-) equiv for hydrogen production at a higher VLR condition. However, a maximum lactate/acetate concentration allowed for enriching this culture existed, especially at a lower HRT condition in which wash-out can be an issue for this enriched culture. Finally, the results of cloning and sequencing indicated that Clostridium tyrobutyricum was considered the major hydrogen-producing bacteria in the CSTR fed with lactate and acetate. PMID:22318084

Wu, Chao-Wei; Whang, Liang-Ming; Cheng, Hai-Hsuan; Chan, Kan-Chi

2012-06-01

204

The microwave spectrum of n-hexyl acetate and structural aspects of n-alkyl acetates  

NASA Astrophysics Data System (ADS)

The microwave spectrum of n-hexyl acetate was recorded in the range of 10-13.5 GHz using the Aachen MB-FTMW spectrometer. The rotational constants of the most abundant conformer were determined to be A = 3.3591100(32) GHz, B = 0.39596553(53) GHz, and C = 0.36999804(31) GHz. Quantum chemical calculations for specific conformers were carried out at the MP2/6-311++G(d,p) level. The programs XIAM and BELGI were used to analyze the internal rotation of the acetyl methyl group. The observed conformer of n-hexyl acetate was compared to the lowest energy conformers of n-butyl acetate and n-pentyl acetate.

Attig, T.; Kannengießer, R.; Kleiner, I.; Stahl, W.

2014-04-01

205

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

E-print Network

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

Sanglimsuwan, Apiradee

206

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

SciTech Connect

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

Not Available

1992-01-01

207

Volatile organic compounds of polyethylene vinyl acetate plastic are toxic to living organisms.  

PubMed

Volatile organic compounds (VOCs) in polyvinyl chloride (PVC) plastic products readily evaporate; as a result, hazardous gases enter the ecosystem, and cause cancer in humans and other animals. Polyethylene vinyl acetate (PEVA) plastic has recently become a popular alternative to PVC since it is chlorine-free. In order to determine whether PEVA is harmful to humans, this research employed the freshwater oligochaete Lumbriculus variegatus as a model to compare their oxygen intakes while they were exposed to the original stock solutions of PEVA, PVC or distilled water at a different length of time for one day, four days or eight days. During the exposure periods, the oxygen intakes in both PEVA and PVC groups were much higher than in the distilled water group, indicating that VOCs in both PEVA and PVC were toxins that stressed L. variegatus. Furthermore, none of the worms fully recovered during the24-hr recovery period. Additionally, the L. variegatus did not clump together tightly after four or eight days' exposure to either of the two types of plastic solutions, which meant that both PEVA and PVC negatively affected the social behaviors of these blackworms. The LD50 tests also supported the observations above. For the first time, our results have shown that PEVA plastic has adverse effects on living organisms, and therefore it is not a safe alternative to PVC. Further studies should identify specific compounds causing the adverse effects, and determine whether toxic effect occurs in more complex organisms, especially humans. PMID:25242410

Meng, Tingzhu Teresa

2014-01-01

208

Trypanosomatidae Produce Acetate via a Mitochondrial Acetate:Succinate CoA Transferase  

Microsoft Academic Search

Hydrogenosome-containing anaerobic protists, such as the trichomonads, produce large amounts of acetate by an acetate:succinate CoA transferase (ASCT)\\/succinyl CoA synthetase cycle. The notion that mitochondria and hydrogenosomes may have originated from the same alpha -proteobacterial endosymbiont has led us to look for the presence of a similar metabolic pathway in trypanosomatids because these are the earliest-branching mitochondriate eukaryotes and because

Jaap J. van Hellemond; Fred R. Opperdoes; Aloysius G. M. Tielens

1998-01-01

209

Solid–liquid equilibrium in the acetic acid–acetophenone and acetic acid–formamide systems  

Microsoft Academic Search

Solid–liquid equilibrium in the binary systems acetic acid–acetophenone and acetic acid–formamide was determined from time–temperature cooling and warming curves. The first system shows a sagged curve with a eutectic point at x1?0.6 and T=267.18 K. In the second system a solid compound (2:1) was found and an equilibrium constant of the compound dissociation was calculated.

I. Malijevská; Z. Sedláková

2006-01-01

210

Structural design of ketal and acetal blocking groups in two-component chemically amplified positive DUV resists  

NASA Astrophysics Data System (ADS)

In the present study, protecting groups of moderate stability, such as acetals and ketals, were investigated as pendant blocking groups in polyvinyl phenols. Polymers were obtained by reacting enol ethers with the phenolic side groups to form acetal or ketal blocked phenols. Decomposition temperatures, glass transition temperatures, and molecular weights of the resulting polymers were monitored and correlated with the protecting group structure. Stability of the protecting groups can be explained by protonation occurring at either of the two oxygen sites, making two cleavage routes possible. Secondary reactions of the released protecting groups in the resist film were investigated and discussed. The structure of the protecting group was designed in order to meet basic resist properties such as resolution/linearity, DOF, post exposure delay latitude and thermal stability. A Canon FPA 4500 (NA equals 0.37) and a GCA XLS exposure tool (NA equals 0.53) were used for the optimization process. A preoptimized resist formulation based on the above criteria exhibits 0.23 micrometers line/space resolution, 0.8 micrometers focus latitude at 0.25 micrometers resolution and approximately two hours post exposure delay latitude.

Mertesdorf, Carlo; Muenzel, Norbert; Holzwarth, Heinz E.; Falcigno, Pasquale A.; Schacht, Hans-Thomas; Rohde, Ottmar; Schulz, Reinhard; Slater, Sydney G.; Frey, David; Nalamasu, Omkaram; Timko, Allen G.; Neenan, Thomas X.

1995-06-01

211

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

Microsoft Academic Search

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

Mohammed Aleem Abdullah

1998-01-01

212

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

PubMed

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

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

2011-07-01

213

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

214

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

215

Biogas Production through the Syntrophic Acetate-Oxidising Pathway  

E-print Network

retention time OLR Organic loading rate PCR Polymerase chain reaction qPCR Quantitative polymerase chain reaction RNA Ribonucleic acid SAO Syntrophic acetate oxidation SAOB Syntrophic acetate-oxidising bacteria

216

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

SciTech Connect

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

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

1987-09-01

217

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

Microsoft Academic Search

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

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

2003-01-01

218

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

Microsoft Academic Search

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

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

2006-01-01

219

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

Microsoft Academic Search

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

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

2008-01-01

220

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

Microsoft Academic Search

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

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

1997-01-01

221

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

Microsoft Academic Search

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

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

2011-01-01

222

Nanoporous Nanocomposite Hydrogels Composed of Polyvinyl Alcohol and Na-montmorillonite  

Microsoft Academic Search

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

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

2012-01-01

223

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

224

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

Microsoft Academic Search

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

T. Abdul kareem; A. Anu kaliani

2011-01-01

225

Optical property of CdS QD's embeded in Polyvinyl alcohol  

Microsoft Academic Search

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

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

2007-01-01

226

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

Microsoft Academic Search

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

Ji Hwan Son; Yong Soo Kang; Jongok Won

2006-01-01

227

Holograms in polyvinyl alcohol photosensitized with CuCl2(2H2O)  

Microsoft Academic Search

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

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

2011-01-01

228

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

Microsoft Academic Search

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

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

2012-01-01

229

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

Microsoft Academic Search

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

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

2008-01-01

230

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

Microsoft Academic Search

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

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

2006-01-01

231

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

SciTech Connect

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

NONE

1995-12-01

232

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

Microsoft Academic Search

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

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

1991-01-01

233

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

Microsoft Academic Search

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

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

2003-01-01

234

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

Microsoft Academic Search

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

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

2004-01-01

235

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

Microsoft Academic Search

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

B Andri?i?; T Kova?i?

1999-01-01

236

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

Microsoft Academic Search

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

Tonka Kova?i?; Željko Mrkli?

2002-01-01

237

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

Microsoft Academic Search

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

Željko Mrkli?; Tonka Kova?i?

1998-01-01

238

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

Microsoft Academic Search

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

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

2004-01-01

239

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

Microsoft Academic Search

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

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

2005-01-01

240

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

Microsoft Academic Search

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

Tsuyoshi Kawakami; Kazuo Isama; Atsuko Matsuoka

2011-01-01

241

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

242

Separating acetic acid from furol (furfural) by electrodialysis method  

SciTech Connect

Furfural production by hydrolysis of fibrous plant materials is accompanied by formation of acetic acid in amounts depending on the material used. The amount of acetic formed in the hydrolysis of the fruit shell of oil-tea camellia (Camellia oleosa) (an oilseed-bearing tree) is equal to the amount of furfural. The acetic acid can be separated from the furfural and concentrated to 10% by electrodialysis. A smaller amount of furfural is separated with acetic acid.

Guan, S.F.; Li, C.S. Ye, S.T.; Shen, S.Y.; Wang, Y.T.; Yu, S.H.

1981-01-01

243

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

244

l-Lysinium trifluoro-acetate.  

PubMed

Ions of the title compound, C(6)H(15)N(2)O(2) (+)·C(2)F(3)O(2) (-), a new organic nonlinear optical crystal, are linked by N-H?O hydrogen-bonding inter-actions. Both the amino groups of the l-lysinium cation are protonated. A three-dimensional network of hydrogen bonds is observed, forming a closed ring. Inter-molecular N-H?O hydrogen bonds involving l-lysinium cations and trifluoro-acetate anions link the ions into extended chains which run parallel to the [010] direction. The F atoms of the trifluoro-acetate anion are disordered over two sites with site occupancies of 0.423?(18) and 0.577?(18). The asymmetric unit consists of two cations and two anions. PMID:21201423

Sun, Zhi Hua; Fan, Jian Dong; Zhang, Guang Hui; Wang, Xin Qiang; Xu, Dong

2008-01-01

245

Functional Properties of Extruded Starch Acetate Blends  

Microsoft Academic Search

Starch acetate, with degree of substitution of 2, was blended with 0, 7.5 and 15% polylactic acid (PLA), Eastar Bio Copolyester 14766 (EBC) or Mater-Bi ZF03U (MBI) and 10%, 13%, or 16% (d.b.) ethanol and twin-screw extruded at 160°C barrel temperature. Physical characteristics of the extrudates, such as radial expansion ratio, unit and bulk densities, and of the mechanical properties,

J. Guan; Q. Fang; M. A. Hanna

2004-01-01

246

Corrosion of Stainless Steel During Acetate Production  

Microsoft Academic Search

Corrosion of types 304, 304L, 316, and 316L stainless steel (SS) during the esterification of acetic acid and alcohol or glycol ether was investigated. The catalyst for this reaction, sulfuric acid or para-toluene sulfonic acid (PTSA), was shown to cause more corrosion on reactor equipment than CHâCOOH under the process conditions commonly practiced in industry. The corrosive action of the

J. S. Qi; G. C. Lester

1996-01-01

247

Lithium acetate transformation of yeast Maitreya Dunham August 2004  

E-print Network

Lithium acetate transformation of yeast Maitreya Dunham August 2004 Original protocol from Katja until the OD600 is around 0.7-0.8 (~7 hours). Spin down the cells. Resuspend in 5 ml lithium acetate mix. Spin. Resuspend in 0.5 ml lithium acetate mix. Transfer to an eppendorf tube. Incubate 60 minutes

Dunham, Maitreya

248

Development of an Amperometric Acetic Acid Sensor in Organic System  

Microsoft Academic Search

An amperometric method was developed by using a lead working electrode in acetonitrile organic solution for detecting acetic acid. The mechanisms of electrochemical reaction were corresponding to the reduction of acetic ions in acetonitrile organic solution. The steady state amperometric current resulted from the reduction of acetic ions to produce the aldehyde in a two-electron process. In the organic sensing

Shin Lin; Tse-Chuan Chou

249

Effects of nitrobenzene and zinc on acetate utilizing methanogens  

Microsoft Academic Search

Determination of anaerobic degradation rates and toxic effects of nitrobenzene (NB) on acetate utilizing methanogens was the first objective of this research. Serum bottles were used for anaerobic toxicity assays with an acetate enrichment culture of methanogens. Ten mg\\/l of nitrobenzene did not inhibit total gas production in the acetate enrichment methanogenic culture. Twenty and thirty mg\\/l of nitrobenzene caused

Sanjoy K. Bhattacharya; Mingbo Qu; Richard L. Madura

1996-01-01

250

Thermochemical characteristics of cellulose acetates with different degrees of acetylation  

NASA Astrophysics Data System (ADS)

The standard enthalpies of combustion and formation of cellulose acetates with different degrees of acetylation are determined. It is established that there is a proportional dependence of these thermochemical characteristics vs. the degree of acetylation, weight fraction of bonded acetic acid, and molar mass of the repeating unit of cellulose acetates.

Larina, V. N.; Ur'yash, V. F.; Kushch, D. S.

2012-12-01

251

Application of mixtures of polymeric carriers for dissolution enhancement of oxeglitazar using hot-melt extrusion.  

PubMed

Hot-melt extrusion was applied to improve the solubility of the poorly water-soluble drug oxeglitazar. Various polymers and their blends were used as carriers: copovidone (COP), polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol copolymer (PVCL-PVAc-PEG) and hypromellose 2910/5 (HPMC). After extrusion, the extrudate was pelletized. The physical state of the drug was assessed using X-ray diffraction and differential scanning calorimetry. The dissolution performance of the extrudates was compared to the physical mixture and pure oxeglitazar. The stability under long-term storage conditions (25 °C/60%rH) was investigated.The solubility of oxeglitazar was improved with all hot-melt extruded formulations: 26-66% of the drug was dissolved and a 1.9-5.0-fold supersaturation was reached with the pelletized extrudates. All extrudates which were assessed for their storage stability showed sufficient product stability. A super-additive effect of COP and HPMC as a polymeric blend was successfully demonstrated as a higher supersaturation and longer time of supersaturation were shown for the ternary blend. Through variations of the ratio COP:HPMC, it was shown that the shape of the dissolution curve is dominated by the polymer with the higher amount in the polymeric blend. If PVCL-PVAc-PEG is applied as single or additional carrier, the initial release rate is drastically reduced. PMID:23073606

Kalivoda, Adela; Fischbach, Matthias; Kleinebudde, Peter

2012-12-15

252

Application of mixtures of polymeric carriers for dissolution enhancement of fenofibrate using hot-melt extrusion.  

PubMed

Hot-melt extrusion was applied to improve dissolution behavior of poorly soluble model drug fenofibrate. Blends of polymers were used as carrier: copovidone (COP), polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol copolymer (PVCL-PVAc-PEG) and hypromellose 2910/5 (HPMC). The ratio of fenofibrate to COP remained constantly 1+3 (weighted parts) with varying amounts of PVCL-PVAc-PEG and HPMC. Solid state of fenofibrate was characterized by X-ray diffractometry and differential scanning calorimetry. Dissolution performance was compared to marketed formulations Lipidil and Lipidil-Ter. Stability studies were conducted at 25°C/60%rH. The dissolution rate from extrudates was significantly increased when compared to pure fenofibrate powder or physical mixture of the components. A supersaturation of 7.6-12.1 was reached with the pelletized extrudates. All extrudates were superior to marketed formulations. No recrystallization was observed after 26 weeks of storage for fenofibrate-COP extrudates 1+3 (weighted parts) with or without polymeric additives. Even so, both degree and duration of supersaturation decreased with increasing storage periods with the exception of fenofibrate-HPMC extrudates. Of particular interest is the finding that by adding polymers with differing release characteristics to the drug-carrier mixture, the dissolution performance of hot-melt extruded solid dosage forms can be readily adapted to meet specific requirements. PMID:22440149

Kalivoda, Adela; Fischbach, Matthias; Kleinebudde, Peter

2012-06-15

253

Acetate supplementation attenuates lipopolysaccharide-induced neuroinflammation  

PubMed Central

Glyceryl triacetate (GTA), a compound effective at increasing circulating and tissue levels of acetate was used to treat rats subjected to a continual 28 day intra-ventricular infusion of bacterial lipopolysaccharide (LPS). This model produces a neuroinflammatory injury characterized by global neuroglial activation and a decrease in choline acetyltransferase immunoreactivity in the basal forebrain. During the LPS infusion, rats were given a daily treatment of either water or GTA at a dose of 6g/kg by oral gavage. In parallel experiments free-CoA and acetyl-CoA levels were measured in microwave fixed brains and flash frozen heart, liver, kidney and muscle following a single oral dose of GTA. We found that a single oral dose of GTA significantly increased plasma acetate levels by 15 min and remained elevated for up to 4 hr. At 30 min the acetyl-CoA levels in microwave-fixed brain and flash frozen heart and liver were increased at least 2.2-fold. The concentrations of brain acetyl-CoA was significantly increased between 30 and 45 min following treatment and remained elevated for up to 4 hr. The concentration of free-CoA in brain was significantly decreased compared to controls at 240 min. Immunohistochemical and morphological analysis demonstrated that a daily treatment with GTA significantly reduced the percentage of reactive GFAP-positive astrocytes and activated CD11b-positive microglia by 40–50% in rats subjected to LPS-induced neuroinflammation. Further, in rats subjected to neuroinflammation, GTA significantly increased the number of ChAT-positive cells by 40% in the basal forebrain compared to untreated controls. These data suggest that acetate supplementation increases intermediary short chain acetyl-CoA metabolism and that treatment is potentially anti-inflammatory and neuroprotective with regards to attenuating neuroglial activation and increasing ChAT immunoreactivity in this model. PMID:21272004

Reisenauer, Chris J.; Bhatt, Dhaval P.; Mitteness, Dane J.; Slanczka, Evan R.; Gienger, Heidi M.; Watt, John A.; Rosenberger, Thad A.

2011-01-01

254

2-Amino-pyridinium trifluoro-acetate.  

PubMed

The asymmetric unit of the title compound, C(5)H(7)N(2) (+)·C(2)F(3)O(2) (-), contains four independent 2-amino-pyridinium cations and four independent trifluoro-acetate anions. In the crystal structure, these ions are linked by N-H?O hydrogen bonds, forming four cation-anion pairs each containing an R(2) (2)(8) ring motif. The ion pairs are linked into two independent chains along [100] by N-H?O hydrogen bonds. In addition, C-H?O and C-H?F hydrogen bonds and ??? inter-actions [centoid-centroid separation = 3.6007?(17)?Å] are observed. PMID:21580433

Hemamalini, Madhukar; Fun, Hoong-Kun

2010-01-01

255

Modeling drug release from PVAc/PVP matrix tablets.  

PubMed

Kollidon SR-based matrix tablets containing various amounts of diprophylline were prepared and thoroughly characterized in vitro. This includes drug release measurements in 0.1M HCl and phosphate buffer pH 7.4, monitoring of changes in the tablet's height and diameter, morphology as well as dry mass upon exposure to the release media. Based on these experimental results, a mechanistic realistic mathematical theory is proposed, taking into account the given initial and boundary conditions as well as radial and axial mass transport in cylinders. Importantly, good agreement between theory and experiment was obtained in all cases, indicating that drug diffusion with constant diffusivity is the dominant mass transport mechanism in these systems. Furthermore, the proposed theory was used to quantitatively predict the effects of the initial tablet height and diameter on the resulting drug release patterns. These theoretical predictions were compared with independently measured drug release kinetics. Good agreement was observed in all cases, proving the validity of the mathematical theory and illustrating the latter's practical benefit: The model can help to significantly facilitate the recipe optimization of this type of advanced drug delivery systems in order to achieve a desired release profile. PMID:19737588

Siepmann, F; Eckart, K; Maschke, A; Kolter, K; Siepmann, J

2010-01-25

256

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

257

Red-green-blue laser emissions from dye-doped poly(vinyl alcohol) films.  

PubMed

A microscope slide acting as a passive waveguide was coated by three separate poly(vinyl alcohol) films that were doped with Coumarin 460, Disodium Fluorescein, and Rhodamine 640 perchlorate. On collinear pumping by a nitrogen laser, these dyes furnished primary red-green-blue laser emissions that were collected and waveguided by the microscope slide but exited from both ends. Frosting the waveguide exit introduced light scattering at the glass-air interface and spatially overlaid the red-green-blue laser emissions that emerged as a uniform white-light beam. PMID:11921803

Yap, Seong-Shan; Siew, Wee-Ong; Tou, Teck-Yong; Ng, Seik-Weng

2002-03-20

258

Poly(vinyl chloride) ion-selective electrodes for Piribedil determination  

Microsoft Academic Search

Piribedil (PD) ion-selective electrodes have been constructed from poly(vinyl chloride) matrix membrane containing piribedil-tetraphenylborate (PD-TPB) as the electroactive component with dibutylphthalate or dioctylphthalate as the plasticizing solvent mediator. The electrodes displayed a linear response over the concentration range 2.0×10?5 to 10?2 M PD. The working pH ranges of the electrodes were 3.5–6.4 and 3.0–6.0, and the isothermal coefficients of the

Y. M Issa; M. M Hassouna; F. M Abdel-Gawad; E. M Hussien

2000-01-01

259

Effect of borax concentration on the structure of Poly(Vinyl Alcohol) gels  

NASA Astrophysics Data System (ADS)

Poly(Vinyl Alcohol) hydrogels cross-linked with varying concentrations of borax have been studied using Small-Angle Neutron Scattering and X-Ray Diffraction. The intensity of scattering increases with borax concentration from 1 mg/ml up to 2 mg/ml and falls thereafter for 4 mg/ml, increasing again for a concentration of 10 mg/ml. The mesoscopic structural changes that cause these trends in the SANS data are in keeping with the variations in the X-ray diffraction patterns pertaining to structures within the PVA chains.

Lawrence, Mathias B.; Desa, J. A. E.; Aswal, V. K.

2012-06-01

260

Flexible polyvinyl chloride neutron guides for transporting ultracold and very cold neutrons  

SciTech Connect

The transmission of ultracold neutrons (UCNs) through flexible polyvinyl chloride (PVC) tubes with lengths of up to 3 m and an internal diameter of 6-8 mm has been studied. High UCN transmission is found even for arbitrarily bent tubes (single bend, double bend, triple bend, figure eight, etc.). The transmission can be improved significantly by coating the inner surface of the tube with a thin layer of liquid fluorine polymer. The prospects of these neutron guides in fundamental and applied research are discussed.

Arzumanov, S. S., E-mail: sarzumanov@yandex.ru; Bondarenko, L. N. [Russian Research Center Kurchatov Institute (Russian Federation); Geltenbort, P. [Institut Laue-Langevin (France); Morozov, V. I. [Russian Research Center Kurchatov Institute (Russian Federation); Nesvizhevsky, V. V. [Institut Laue-Langevin (France); Panin, Yu. N.; Strepetov, A. N.; Chuvilin, D. Yu. [Russian Research Center Kurchatov Institute (Russian Federation)

2011-12-15

261

Role of metal oxides in the thermal degradation of poly(vinyl chloride)  

SciTech Connect

Thermal degradation of poly(vinyl chloride) has been studied in the presence of metal oxides by a thermogravimetric method. It follows a two-step mechanism. In the first step chlorine free radical is formed as in the case of pure PVC, and in the second step chlorine free radical replaces oxygen from metal oxide to form metal chloride and oxygen free radical. Subsequently, the oxygen free radical abstracts hydrogen from PVC. Formation of metal chloride is the rate-controlling step. The metal chlorides formed during the thermal degradation either volatilize or decompose simultaneously to lower metallic chlorides depending on the boiling point or the volatilization temperature.

Gupta, M.C.; Viswanath, S.G. [Nagpur Univ. (India)] [Nagpur Univ. (India)

1998-07-01

262

Synthesis of Nanocomposites of Polyvinyl Alcohol with Silver Nanoparticles and Their Use  

NASA Astrophysics Data System (ADS)

Composites of polyvinyl alcohol (PVA) containing silver nanoparticles were prepared using in situ synthesis of nanoparticles. Structure and properties of these composites were investigated using UV-Vis spectroscopy, XRD, DSC, SEM and AFM. The studies show that PVA can reduce the AgNO3 to yield silver nanoparticles and in the process forms bonds with PVA chains. The anti-bacterial properties of these films were studied by qualitative as well as quantitative methods which gave the values of 98% for gram positive and 89% for gram negative bacteria.

Bhat, N. V.; Karmakar, N. S.; Kothari, D. C.

2013-08-01

263

Structural changes of human serum albumin induced by cadmium acetate.  

PubMed

The structural changes of human serum albumin (HSA) induced by the addition of cadmium acetate were systematically investigated using UV-vis absorption, circular dichroism (CD), synchronous, and three-dimentional (3D) fluorescence methods. The fluorescence spectra suggested the formation of cadmium acetate-HSA complex. UV absorption result indicated that the interaction between cadmium acetate and HSA could lead to the alteration of the protein skeleton. The structural analysis according to CD method showed that the cadmium acetate binding altered HSA conformation with a major reduction of ?-helix, inducing a partial protein unfolding. Synchronous fluorescence spectra suggested that cadmium acetate was situated closer to tryptophan residue compared to tyrosine residues, making tryptophan residue locate in a more hydrophobic environment. 3D fluorescence demonstrated that cadmium acetate could induce the HSA aggregation and cause a slight unfolding of the polypeptide backbone of the protein. PMID:24771482

Chen, Mingmao; Guo, Hao; Liu, Yan; Zhang, Qiqing

2014-06-01

264

Acetate absorption and metabolism in the rabbit hindgut.  

PubMed Central

Acetate disappearance from the loops of the hindgut in the rabbit was evaluated by measuring variations in the concentration of acetate in caecocolonic loops and differences in the arterial and venous plasma. In vivo metabolism in gut and liver tissues was studied after introduction of (1-14C) acetate into caecocolonic loops. The rate of disappearance from the loops was quantitatively significant and showed little variation irrespective of the location in the hindgut. Hindgut tissue metabolised acetate and the intensity of the metabolism varied with the segment studied. The distal position of the gut showed by far the highest acetate uptake. Radioactivity was found in a certain number of free amino acids, organic acids, and sugars. Acetate was mainly converted into aspartate and glutamate. These can be considered as 'stock forms' which can be diverted either towards oxidative metabolism or towards protein synthesis. Images Fig. 1 PMID:4007603

Marty, J F; Vernay, M Y; Abravanel, G M

1985-01-01

265

Effect of medroxyprogesterone acetate (Provera) on ovarian radiosensitivity  

SciTech Connect

Medroxyprogesterone acetate (Provera) is a drug that is commonly given to young women with cancer during chemotherapy and radiation to control heavy bleeding associated with anovulation. Because hypothalamic-pituitary-ovarian suppression has been associated with ovarian protection from the effects of chemotherapy and medroxyprogesterone acetate has been identified as a radiosensitizing agent, we explored the effects of medroxyprogesterone acetate on a rat model with known radiation injury characteristics. Sprague-Dawley rats were treated with medroxyprogesterone acetate or vehicle from day 22 to day 37 of life and were either irradiated or sham-irradiated on day 30 of life and then killed on day 44. Radiation with medroxyprogesterone acetate administration produced a greater loss in preantral and healthy control follicles than in control follicles. No suppression of luteinizing hormone or follicle-stimulating hormone had occurred by day 30 but ovarian glutathione content was reduced. These findings indicate that the administration of medroxyprogesterone acetate with radiotherapy may enhance ovarian injury.

Jarrell, J.; YoungLai, E.V.; McMahon, A.; Barr, R.; O'Connell, G.; Belbec, L.

1989-04-01

266

Nutrient requirements for high rate conversion of acetate to methane  

Microsoft Academic Search

In this research, nutrient requirements for high rate conversion of acetate to methane were examined with acetate enrichment cultures at 35°C. By employing a pH stat as the cultivation system, the pH and acetate concentration were maintained, respectively, at about 6.8 and greater than or equal to 2000 mg\\/l in the reactor. Ni and Fe limitation in the pH stat

Takashima

1987-01-01

267

Mesophilic syntrophic acetate oxidation during methane formation in biogas reactors  

Microsoft Academic Search

The reaction pathway for the formation of methane from acetate was investigated in sludge from 13 different biogas reactors. By following the conversion of [2-14C]acetate and [14C]bicarbonate it was shown that methane formation by syntrophic acetate oxidation was the dominating mechanism for acetotrophic methanogenesis in sludge containing high levels of salts, mainly ammonium, and volatile fatty acids. In one biogas

Anna Schnürer; Gerhard Zellner; Bo H. Svensson

1999-01-01

268

21 CFR 522.1410 - Sterile methylprednisolone acetate suspension.  

Code of Federal Regulations, 2010 CFR

...with methylprednisolone acetate, as with other corticoids, is contraindicated in animals with arrested tuberculosis, peptic ulcer, and Cushing's syndrome. The presence of active tuberculosis, diabetes mellitus, osteoporosis, renal...

2010-04-01

269

21 CFR 522.1410 - Sterile methylprednisolone acetate suspension.  

Code of Federal Regulations, 2011 CFR

...with methylprednisolone acetate, as with other corticoids, is contraindicated in animals with arrested tuberculosis, peptic ulcer, and Cushing's syndrome. The presence of active tuberculosis, diabetes mellitus, osteoporosis, renal...

2011-04-01

270

Aryl Acetate Phase Transfer Catalysis: Method and Computation Studies.  

E-print Network

??Brief explanation and history of cinchona based Phase Transfer Catalysis (PTC). Studied aryl acetates in PTC, encompassing napthoyl, 6-methoxy napthoyl, phenyl and protected 4-hydroxy phenyl… (more)

Binkley, Meisha A

2011-01-01

271

Polypyrrole based strong acid catalyst for acetalization  

NASA Astrophysics Data System (ADS)

Novel polypyrrole based acid catalyst has been synthesized through the neutralization reaction of polypyrrole and sulfuric acid. The polypyrrole based acid owned the acidity as high as 6.0 mmol/g, which was much higher than that of the traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activities of the novel solid acid were investigated through the acetalization. The results showed that the novel solid acid held high activities for the reactions. Furthermore, the recycled activities of the catalyst indicated that the solid acid owned high stability during the catalytic process and little acid sites dropped from polypyrrole. The high acidity and stability made the novel polypyrrole based acid hold great potential for the green chemical processes.

Liang, Xuezheng; Cheng, Yuxiao; Qi, Chenze

2011-09-01

272

Synthesis and regeneration of lead (IV) acetate  

SciTech Connect

Lead acetate [Pb(O{sub 2}CMe){sub 4}] was easily synthesized from a warm solution of Pb{sub 3}O{sub 4}, HO{sub 2}CMe and O(OCMe){sub 2} following literature preparations when the appropriate measures to minimize water contamination were followed. Furthermore, Pb(O{sub 2}CMe){sub 4} which has been decomposed (evidenced by the appearance of a purple color due to oxidation) can be regenerated using a similar preparatory route. Introduction of Pb(O{sub 2}CMe){sub 4} from the two routes outlined above into the IMO process for production of PZT thin films gave films with comparable ferroelectric properties to commercially available Pb(O{sub 2}CMe){sub 4} precursors. However, the freshly synthesized material yields PZT films with better properties compared to the recycled material.

Boyle, T.J.; Al-Shareef, H.N.; Moore, G.J. [Sandia National Labs., Albuquerque, NM (United States). Advanced Materials Lab.

1996-11-01

273

DEOXYRIBONUCLEIC ACID HYBRIDS OF ACETIC ACID BACTERIA  

PubMed Central

De Ley, J. (State University, Ghent, Belgium), and S. Friedman. Deoxyribonucleic acid hybrids of acetic acid bacteria. J. Bacteriol. 88:937–945. 1964.—Deuterated N15-labeled deoxyribonucleic acid (DNA) from Acetobacter aceti (mesoxydans 4) forms hybrids with ordinary DNA from other species of this genus (A. xylinum, A. pasteurianus, A. estunensis, and possibly A. xylinoides) when the guanine plus cytosine base composition does not vary by more than 1 to 2%. Beyond this limit (A. aceti Ch31 and A. muciparus 5) no hybrids are formed. The hybrids are apparently derived from an asymmetrical part of the compositional distribution. The results lend strength to the concept of a genetic species rather than to a division of a genus into sharply separated species, based on small phenotypic differences. Taxonomic implications are discussed. PMID:14219057

De Ley, J.; Friedman, S.

1964-01-01

274

Band gap energy and optical transitions in polyenes formed by thermal decomposition of polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

The band gap of the ensemble of oligoene clusters formed by thermocatalytic decomposition of polyvinyl alcohol is parametrized using optical absorption spectra. A band gap energy of E gm =1.53 ± 0.02 eV at the end of an infinite polyene chain is found by extrapolating the energies of ? ? ?* transitions in clusters with a number of double bonds varying from 4 to 12. This value is close to the band gap of trans-polyacetylene and the lower bound for the Tauc energy E gT =1.50 eV, which characterizes the minimum interband transition energy. E gT is essentially independent of the concentration of oligoene clusters, which is determined by the concentration of the AlCl3 thermal decomposition catalyst. The Urbach energy determined from the long wavelength edge of the spectrum falls from 2.21 to 0.66 eV as the AlCl3 concentration is raised from 11.1 to 41.7 mmol per mol of polyvinyl alcohol structural units.

Kulak, A. I.; Bondarava, G. V.; Shchurevich, O. A.

2013-07-01

275

Properties of novel polyvinyl alcohol/cellulose nanocrystals/silver nanoparticles blend membranes.  

PubMed

Novel polyvinyl alcohol (PVA) blend membranes containing cellulose nanocrystals (CNs) and silver nanoparticles (AgNPs) were prepared via a simple method. CNs were prepared by sulfuric acid treatment of microcrystalline cellulose. AgNO3 aqueous solution mixed with the CNs aqueous suspension and was reduced by NaBH4 at room temperature. Purified CNs/AgNPs nanocomposites as functional fillers mixed with polyvinyl alcohol to prepare blend membrane. The morphology, mechanical properties, and antibacterial activities of PVA/CNs/AgNPs composite films were investigated. The PVA/CNs/AgNPs composite films were stable and homogeneous. The tensile strength of PVA was increased from 57.02 MPa to 81.21 MPa when filled with CNs/AgNPs. Antibacterial ratio of PVA/CNs/AgNPs composite against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was 96.9% and 88.2%, respectively. The CNs/AgNPs nanocomposites could be applied as bi-functional nanofillers within PVA to improve the mechanical properties and antibacterial activities. PMID:24053842

Xu, Xu; Yang, Yi-Qin; Xing, Ying-Ying; Yang, Jiu-Fang; Wang, Shi-Fa

2013-11-01

276

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

277

Acute health effects among firefighters exposed to a polyvinyl chloride (PVC) fire  

SciTech Connect

Firefighters are frequently being called on to fight fires that are chemical in nature. In the aftermath of a chemical fire in Plainfield, New Jersey on March 20-21, 1985, the authors conducted a retrospective cohort study which surveyed 80 firefighters exposed to burning polyvinyl chloride (PVC) as well as 15 nonexposed firefighter subjects. By means of an 81-item symptom checklist, exposed firefighters reported more frequent and severe symptoms at 5-6 weeks post incident. This was true for a total symptomatology score as well as 19 individual items. Some of the items with an elevated risk were consistent with exposure to hydrogen chloride, the main pyrolysis product of polyvinyl chloride. Other items with an elevated risk appeared to be related to smoke inhalation while others seemed psychosocial in nature. Analyses conducted within the exposed firefighter group showed that fighting the fire the first day, being a truckman, and residence within 1 mile (1.6 km) of the firehouse were significant risk factors for high total symptom scores. These risk factors may have been associated with level or duration of exposure to the toxic substances produced during the fire.

Markowitz, J.S.; Gutterman, E.M. (New York State Psychiatric Institute (USA)); Schwartz, S.; Link, B.; Gorman, S.M. (Columbia Univ., New York (USA))

1989-05-01

278

Formulation and evaluation of an in situ gel forming system for controlled delivery of triptorelin acetate.  

PubMed

The novel physical hydrogels composed of chitosan or its water soluble derivatives such as carboxymethyl chitosan (CMCh) and sodium carboxymethyl chitosan (NaCMCh) and opened ring polyvinyl pyrrolidone (OP-PVP) were used as a controlled delivery system for triptorelin acetate, a luteinizing-releasing hormone agonist. The in situ gel forming system designed according to physical interactions such as chains entanglements and hydrophilic attractions especially h-bonds of chitosan and/or NaCMCh and OR-PVP. In order to increase in situ gel forming rate the chitosan microspheres prepared through spray drying technique. The chitosan or NaCMCh/OR-PVP blends prepared at different ratios (0.05, 0.10, 0.12, 0.16, 0.20 and 0.24) and suspended in sesame oil as non-aqueous vehicle at different solid content (10-30%). The suitable ratio of polymers with faster in situ gel forming rate was selected for in vivo studies. The gel formation and drug release from the system was evaluated both in vitro and in vivo. In vitro and in vivo results were compared with Diphereline SR 3.75mg, a commercially available controlled delivery system of triptorelin. In vitro release studies showed a sustained release profile for about 192h with first order kinetics. In vivo studies on male rats by determination of serum testosterone were confirmed the acceptable performance of in situ gel forming system compared with Diphereline SR in decreasing the serum testosterone level for 35days, demonstrating the potential of the novel in situ gel forming system for controlled delivery of peptides. PMID:21946260

Abashzadeh, Sh; Dinarvand, R; Sharifzadeh, M; Hassanzadeh, G; Amini, M; Atyabi, F

2011-11-20

279

Role of apoptosis in uranyl acetate-induced acute renal failure and acquired resistance to uranyl acetate  

Microsoft Academic Search

Role of apoptosis in uranyl acetate-induced acute renal failure and acquired resistance to uranyl acetate.BackgroundWe have previously reported that animals recovering from uranyl acetate (UA)-induced acute renal failure (ARF) were resistant to subsequent insult. Recent evidence suggests that apoptosis participates in tubular damage. We investigated the role of apoptosis in UA-induced ARF and attenuation of ARF in acquired resistance to

Koji Sano; Yoshihide Fujigaki; Takehiko Miyaji; Naoki Ikegaya; Kazuhisa Ohishi; Katsuhiko Yonemura; Akira Hishida

2000-01-01

280

Phase and reaction equilibria of acetic acid–1-pentanol–water– n-amyl acetate system at 760 mm Hg  

Microsoft Academic Search

The esterification reaction of acetic acid and alcohol is one of the processes applying reactive distillation technology. It is known that the thermodynamic properties are essential to chemical process design. In this study, the thermodynamic behaviors of vapor–liquid equilibrium (VLE) and reaction equilibrium of acetic acid, 1-pentanol, n-amyl acetate, and water mixture were determined experimentally. Since the present esterification reaction

Liang-sun Lee; Shen-jang Liang

1998-01-01

281

Oxidation of indole-3-acetic acid to oxindole-3-acetic acid by an enzyme preparation from Zea mays  

NASA Technical Reports Server (NTRS)

Indole-3-acetic acid is oxidized to oxindole-3-acetic acid by Zea mays tissue extracts. Shoot, root, and endosperm tissues have enzyme activities of 1 to 10 picomoles per hour per milligram protein. The enzyme is heat labile, is soluble, and requires oxygen for activity. Cofactors of mixed function oxygenase, peroxidase, and intermolecular dioxygenase are not stimulatory to enzymic activity. A heat-stable, detergent-extractable component from corn enhances enzyme activity 6- to 10-fold. This is the first demonstration of the in vitro enzymic oxidation of indole-3-acetic acid to oxindole-3-acetic acid in higher plants.

Reinecke, D. M.; Bandurski, R. S.

1988-01-01

282

Thermal decomposition of pyridine-substituted cobaltic acetate in acetic acid.  

PubMed

The thermal decomposition of [py(3)Co(3)O(OAc)(5)OH][PF(6)] in acetic acid solution in the absence of oxygen produced carbon dioxide, methane, carbon monoxide, picoline, and formic acid as the major products. The ratio of the products was affected by the water concentration and acidity of the mixture. Increased water concentration caused a decrease in methane and an increase in carbon monoxide. Decreased acidity resulted in an increase in methane and a decrease in carbon monoxide. Isotopic labeling experiments showed that some of the carbon monoxide originated as the carboxyl group of the acetic acid. Labeling experiments also showed that formaldehyde and formic acid could be converted to carbon monoxide under the reaction conditions. Two pathways leading to the formation of carbon monoxide were proposed; one involving the decomposition of glyoxylic acid and another involving the oxidation of the methyl radical by cobalt(III). PMID:20397646

Sumner, Charles E; Little, James; Howard, Adam S; Liang, Weimin C

2010-05-17

283

Theoretical studies of molecular structure and vibrational spectra of melaminium acetate acetic acid solvate monohydrate.  

PubMed

The molecular geometry and vibrational frequencies of melaminium acetate acetic acid solvate monohydrate in the ground state have been calculated by using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31++G(d,p) basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The molecule contains the weak hydrogen bonds of N-H...O and O-H...O types, and those bonds are calculated with HF and DFT method. The computed vibrational frequencies were used to determine the types of molecular motions associated with each of the experimental bands observed. In addition, calculated results are related to the linear correlation plot of computed data versus experimental geometric parameters and IR data. PMID:20692201

Pekparlak, A; Avci, D; Cömert, H; Atalay, Y

2010-10-15

284

Origin and fate of acetate in an acidic fen.  

PubMed

Acetate is a central intermediate in the anaerobic degradation of organic matter, and the resolution of its metabolism necessitates integrated strategies. This study aims to (1) estimate the contribution of acetogenesis to acetate formation in an acidic fen (pH ~ 4.9), (2) assess the genetic potential for acetogenesis targeting the fhs gene encoding formyltetrahydrofolate synthetase (FTHFS) and (3) unravel the in situ turnover of acetate using stable carbon isotope pore-water analysis. H(2)/CO(2)-supplemented peat microcosms yielded (13)C-depleted acetate (-37.2‰ vs. VPDB (Vienna Peedee belemnite standard) compared with -14.2‰ vs. VPDB in an unamended control), indicating the potential for H(2)-dependent acetogenesis. Molecular analysis revealed a high diversity and depth-dependent distribution of fhs phylotypes with the highest number of operational taxonomic units in 0-20 cm depth, but only few and distant relationships to known acetogens. In pore waters, acetate concentrations (0-170 ?M) and ?(13)C-values varied widely (-17.4‰ to -3.4‰ vs. VPDB) and did not indicate acetogenesis, but pointed to a predominance of sinks, which preferentially consumed (12)C-acetate, like acetoclastic methanogenesis. However, depth profiles of methane and ?(13)C(CH4) revealed a temporarily and spatially restricted role of this acetate sink and suggest other processes like sulfate and iron reduction played an important role in acetate turnover. PMID:22404042

Hädrich, Anke; Heuer, Verena B; Herrmann, Martina; Hinrichs, Kai-Uwe; Küsel, Kirsten

2012-08-01

285

Cyclization of ?-terpenols and their acetates by fluorosulfonic acid  

Microsoft Academic Search

It has been shown that the superacid cyclization of ?-terpenols and their acetates takes place with structural selectivity\\u000a and chemo- and stereospecificity and leads to cyclic isoprenoids with higher yields than the cyclization of the corresponding\\u000a ?-terpenols and their acetates.

N. D. Ungur; N. P. Popa; Nguen Van Tuen; P. F. Vlad

1993-01-01

286

Addition of acetic acid to styrene catalyzed by ion exchanger  

Microsoft Academic Search

The possibility of preparation of 1-phenylethyl acetate by direct addition of acetic acid to styrene catalyzed by Ostion KS in the acid cycle has been investigated. The reaction is accompanied by the formation of higher molecular compounds. The effect of temperature, mole ratio of the starting compounds, stabilization of styrene, amount of the catalyst and of its repeated use on

L. ?ervený; A. Marhoul; J. Kozel

1988-01-01

287

Interaction between acetate fed sulfate reducers and methanogens  

Microsoft Academic Search

During anaerobic treatment of sulfate containing wastewaters, sulfate reducing bacteria (SRB) and methane producing bacteria (MPB) can compete for acetate as the common primary substrate. Since acetate is an intermediate of anaerobic degradation of complex wastes, the outcome of the competition between SRB and MPB can affect the treatment efficiency. The objective of this research was to determine the effects

S. K. Bhattacharya; V. Uberoi; M. M. Dronamraju

1996-01-01

288

Uptake and turnover of acetate in hypersaline environments  

Microsoft Academic Search

Acetate uptake and turnover rates were determined for the heterotrophic community in hypersaline environments (saltern crystallizer ponds, the Dead Sea) dominated by halpphilic Archaea. Acetate was formed from glycerol, which is potentially the major available carbon source for natural communities of halophilic Archaea. Values of [Kt + Sn] (the sum of the substrate affinity and the substrate concentration present in

Aharon Oren

1995-01-01

289

Characterization of acetic acid bacteria in “traditional balsamic vinegar”  

Microsoft Academic Search

This study evaluated the glucose tolerance of acetic acid bacteria strains isolated from Traditional Balsamic Vinegar. The results showed that the greatest hurdle to acetic acid bacteria growth is the high sugar concentration, since the majority of the isolated strains are inhibited by 25% of glucose. Sugar tolerance is an important technological trait because Traditional Balsamic Vinegar is made with

Maria Gullo; Cinzia Caggia; Luciana De Vero; Paolo Giudici

2006-01-01

290

Cellulose production by acetic acid-resistant Acetobacter xylinum  

Microsoft Academic Search

A bacterium that could produce a gelatinous cellulosic pellicle in the presence of more than 2% acetic acid was isolated as a contaminant in a continuous surface culture for acetic acid production using Acetobacter aceti. The bacterium was identified as a strain belonging to Acetobacter xylinum and designated as strain DA. The production of cellulose in a static culture of

Kiyoshi Toda; Tomoko Asakura; Masahiro Fukaya; Etsuzo Entani; Yoshiya Kawamura

1997-01-01

291

Transition-Metal-Catalyzed Carbonylation of Methyl Acetate.  

ERIC Educational Resources Information Center

Presents a study of the rhodium-catalyzed, ioding-promoted carbonylation of methyl acetate. This study provides an interesting contrast between the carbonylation of methyl acetate and the carbonylation of methanol when similar rhodium/iodine catalyst systems are used. (JN)

Polichnowski, S. W.

1986-01-01

292

Dynamical characterization of a cellulose acetate polysaccharide.  

PubMed

This work brings together dynamical and structural information at a molecular level for cellulose acetate being an original contribution to the general description of polysaccharide properties. In particular, it allowed reinterpreting the secondary relaxation mechanisms that are still controversial in the literature; a compilation of data provided by different authors is provided. Detailed dynamical information is provided by dielectric relaxation spectroscopy (DRS) (10(-1)-10(6) Hz) for cellulose acetate (CA) in the sub-T(g) region below ambient temperature; results were compared with cellulose acetate structured as an asymmetric membrane (CAmb). In samples with low water content, two secondary relaxation processes between 173 and 298 K were identified by DRS, associated with localized mobility. The process located at the lowest temperatures (process I) has a different mobility in CA relative to CAmb. The identical crystalline/amorphous state of both materials allowed rationalizing the distinct behavior in terms of polymeric arrangement and ability for water uptake. The looser structure of the CA relative to CAmb as confirmed by FTIR, TGA, and DSC analysis makes more sites accessible to water molecules, resulting in a higher water retention in CA (2.73% w/w) relative to CAmb (1.60% w/w) and an increased molecular mobility in the former due to a plasticizing effect. In both materials, process I is significantly influenced by hydration, shifting to higher frequencies and lower temperatures upon water uptake. This process seems to be associated with mobility occurring within the monomeric unit, which embraces the two anhydroglucose rings connected by the glycosidic linkage and the polar groups directly attached to it. It should involve a very limited length scale, as suggested by its location, far below the glass transition, and the tau(infinity) value with a low entropic effect. The relaxation process that emerges later, process II, is similar for both samples being much less influenced by water but experiencing a slight antiplasticizing effect shifting to lower frequencies and higher temperatures upon hydration. It should involve side group motions, strongly coupled to the mobility of the anhydroglucose rings, which become hindered probably due to establishment of H-bonds with water molecules. The plasticizing/antiplasticizing effect is being discussed only on the basis of the frequency position of the relaxation peak. Processes I and II merge into a broad relaxation (gamma(dry)) upon water removal in both CA and CAmb, however evolving slower in the former with drying, due to a more disordered structure of CA that allows water to interact with more internal sites in the polymer. At higher temperatures (T > or = 353 K), a process emerges in the high frequency side of the dynamic alpha-relaxation which is compatible with a beta(JG)-relaxation. The structured specimen CAmb provided an additional way to probe the morphological changes undergone by the material when annealed to temperatures higher than 353 K, originating an increase in the dielectric response. This effect can be associated with a skin densification and partial collapse of the membrane porous network, as observed by SEM. PMID:20690651

Sousa, Miriam; Brás, Ana Rita; Veiga, Helena Isabel M; Ferreira, Frederico Castelo; de Pinho, Maria Norberta; Correia, Natália T; Dionísio, Madalena

2010-09-01

293

Acetate addition to an immobilized yeast column for ethanol production  

SciTech Connect

Acetate, a by-product of ethanol fermentation by Saccharomyces cerevisiae, has been shown to inhibit cell growth if present in high concentrations. Consequently, acetate has been considered undesirable in systems where the production rate depends upon steady-state growth. Acetate, however, may be desirable in some systems since it increases the specific rate of ethanol production by increasing the maintenance requirements of the yeast. In immobilized cell reactors using crosslinking method, steady state is not achieved and cell overgrowth is a problem. This article presents the results of a study aimed at taking advantage of the use of acetate, both to reduce cell overgrowth and increase productivity. Various concentrations of acetate were added to batch and plug flow systems, while monitoring the effects on cell growth and ethanol production. The productivity was increased by as much as 50% in an immobilized cell reactor (ICR), while cell growth was greatly reduced. 19 references.

Vega, J.L.; Clausen, E.C.; Gaddy, J.L.

1987-03-01

294

Glycerol acetals as anti-freezing additives for biodiesel.  

PubMed

Glycerol acetals from butanal, pentanal, hexanal, octanal and decanal were prepared with the use of Amberlyst-15 acid resin as catalyst. The glycerol conversion decreases with the size of the hydrocarbon chain. This fact has been associated with formation of micelles and aggregates of the aldehyde to minimize the interaction between the polar glycerol molecule with the hydrocarbon chain. The Z+E mixture of the acetals with five and six-member rings were produced in all cases. The distribution of the acetal isomers varied with the reaction time, especially for the long chain aldehydes. Addition of 5 vol.% of the butanal-glycerol acetal reduced the pour point of animal fat biodiesel (methyl ester) from 18 to 13 degrees C. The decrease in the pour point of the glycerol acetals-biodiesel mixtures were dependent on the size of the hydrocarbon chain and the percent blended. PMID:20304633

Silva, Paulo H R; Gonçalves, Valter L C; Mota, Claudio J A

2010-08-01

295

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

Microsoft Academic Search

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

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

1996-01-01

296

Supercritical extraction of binder containing poly(vinyl butyral) and dioctyl phthalate from barium titanate–platinum multilayer ceramic capacitors  

Microsoft Academic Search

Supercritical extraction using carbon dioxide was examined for the removal of binder from multilayer ceramic capacitors. The binder contained poly(vinyl butyral) (PVB) and dioctyl phthalate (DOP), and the dielectric and metal electrode materials were barium titanate and platinum, respectively. At 40 MPa of carbon dioxide at 95 °C, approximately 55 wt % of the binder could be removed, and this

Rajesh V. Shende; Daniel S. Krueger; Stephen J. Lombardo

2001-01-01

297

Fungal colonization of soil-buried plasticized polyvinyl chloride (pPVC) and the impact of incorporated biocides  

Microsoft Academic Search

Plasticized polyvinyl chloride (pPVC) with or without incorporated biocides was buried in grassland and forest soil for up to 10 months. The change with time in viable counts of fungi on the plastic surface was followed, together with the percentage capable of clearing the two plasticizers dioctyl adipate (DOA) and dioctyl phthalate (DOP). With time fungal total viable counts (TVC)

H. A. Sabev; P. S. Handley; G. D. Robson

2006-01-01

298

Comparison of Pain After Uterine Artery Embolization Using Tris-Acryl Gelatin Microspheres Versus Polyvinyl Alcohol Particles  

Microsoft Academic Search

When compared in a uterine artery embolization (UAE) animal model, Embospheres (ES) (Biosphere Medical, Rockland, MA) were found to induce less uterine ischemia than polyvinyl alcohol (PVA) particles. Given this finding, we aimed to test the hypothesis that ES is associated with less pain after UAE than PVA in human patients. We performed retrospective analysis on data from 72 consecutive

Robert K. Ryu; Reed A. Omary; Michael J. Sichlau; Aheed Siddiqi; Howard B. Chrisman; Albert A. Nemcek Jr; Robert L. Vogelzang

2003-01-01

299

Study on the Far Infrared Ray Emission Property and Adsorption Performance of Bamboo Charcoal\\/Polyvinyl Alcohol Fiber  

Microsoft Academic Search

In this study, bamboo charcoal materials were blended into polyvinyl alcohol (PVA) solution in various proportions to prepare bamboo charcoal\\/PVA fibers. A series of estimation was executed to discuss the performance of above fibers such as far infrared ray emission, heat preservation, deodorization of ammonia gas, and the adsorption of methylene blue. The spectrum of far infrared ray of bamboo

Chin-An Lin; Ta-Chung An; Yi-Hsiung Hsu

2007-01-01

300

Preparation and characterization of hydrophilic modification of polypropylene non-woven fabric by dip-coating PVA (polyvinyl alcohol)  

Microsoft Academic Search

This paper describes a facile approach for the surface modification of polypropylene non-woven fabric (NWF) by PVA (polyvinyl alcohol) to determine its filterability. The NWF surface modification involved the physical adsorption of PVA to immobilize PVA on the NWF surface. Chemical structures and morphological changes of the PVA-modified NWF sample surfaces were characterized in details by attenuated total reflectance Fourier

Chun-Hua Zhang; Feng-lin Yang; Wen-Jun Wang; Bing Chen

2008-01-01

301

VALIDATION OF AN EPA METHOD FOR THE ION CHROMATOGRAPHIC DETERMINATION OF PERCHLORATE IN FERTILIZERS USING A POLYVINYL ALCOHOL GEL RESIN.  

EPA Science Inventory

This paper summarizes the key points of a joint study between the EPA and Metrohm-Peak, Inc., on the use of polyvinyl alcohol [PVA] columns for the ion chromatographic determination of percholorate in aqueous leachates or solutions of fertilizers. A series of fertilizer samples ...

302

Poly(vinyl alcohol)–collagen hydrolysate thermoplastic blends: II. Water penetration and biodegradability of melt extruded films  

Microsoft Academic Search

Water solubility of polyvinyl alcohol (PVA) is related to degree of hydrolysis, molecular weight and modification during blending in the presence of other processing additives. In the present paper the effect of collagen hydrolysate (CH), an abundant waste product of the leather industry, and glycerol on PVA water sensitivity has been investigated. This study is a continuation of the previous

P. Alexy; D. Bakoš; G. Crko?ová; Z. Kramárová; J. Hoffmann; M. Julinová; E. Chiellini; P. Cinelli

2003-01-01

303

The clinical use of PET with 11C-acetate  

PubMed Central

The aim of this review is to evaluate clinical applications of 11C-acetate positron emission tomography (PET). Acetate is quickly metabolized into acetyl-CoA in human cells. In this form it can either enter into the tricarboxylic acid cycle, thus producing energy, as happens in the myocardium, or participate in cell membrane lipid synthesis, as happens in tumor cells. 11C-acetate PET was originally employed in cardiology, to study myocardial oxygen metabolism. More recently it has also been used to evaluate myocardial perfusion, as well as in oncology. The first studies of 11C-acetate focused on its use in prostate cancer. Subsequently, 11C-acetate was studied in other urological malignancies, as well as renal cell carcinoma and bladder cancer. Well differentiated hepatocellular carcinoma represents an 18F-fluoro-deoxyglucose (18F-FDG) PET pitfall, so many authors have proposed to use 11C-acetate in addition to 18F-FDG in studying this tumor. 11C-acetate PET has also been used in other malignancies, such as brain tumors and lung carcinoma. Some authors reported a few cases in which 11C-acetate PET incidentally found multiple myeloma or rare tumors, such as thymoma, multicentric angiomyolipoma of the kidney and cerebellopontine angle schwannoma. Lastly, 11C-acetate PET was also employed in a differential diagnosis case between glioma and encephalitis. The numerous studies on 11C-acetate have demonstrated that it can be used in cardiology and oncology with no contraindications apart from pregnancy and the necessity of a rapid scan. Despite its limited availability, this tracer can surely be considered to be a promising one, because of its versatility and capacity to even detect non 18F-FDG-avid neoplasm, such as differentiated lung cancer or hepatocellular carcinoma. PMID:23133801

Grassi, Ilaria; Nanni, Cristina; Allegri, Vincenzo; Morigi, Joshua James; Montini, Gian Carlo; Castellucci, Paolo; Fanti, Stefano

2012-01-01

304

Synthesis and properties of cyclic acetal biomaterials.  

PubMed

There is an increasing need to develop new biomaterials as tissue engineering scaffolds. Unfortunately, many of the materials that have been studied for these purposes are polyesters that hydrolytically degrade into acidic products, which may harm the surrounding tissue, and lead to accelerated degradation of the biomaterial. To overcome this disadvantage, a novel class of biomaterials based on a cyclic acetal unit has been created. Specifically, materials based upon the monomer 5-ethyl-5-(hydroxymethyl)-beta,beta-dimethyl-1,3-dioxane-2-ethanol diacrylate (EHD) is examined. This study investigates the effects of fabrication parameters, including initiator content, volume of diluent, and volume of accelerant, on several properties of EHD networks. Twelve different formulations were fabricated by varying the three parameters in a factorial design. The effects of the fabrication parameters on properties of the EHD networks were examined. Results show that the volume of accelerant most affected the EHD network gelation time, while the volume of diluent most affected the maximum reaction temperature, sol fraction, and degree of swelling. Cell viability on the EHD networks varied between (18 +/- 6)% and (57 +/- 10)% of the control at 4 h, and between (36 +/- 14)% and (140 +/- 50)% of the control at 8 h. These results indicate that it is possible to control the properties of the EHD networks by varying the fabrication parameters, and that EHD networks support a viable cell population. PMID:17177269

Moreau, Jennifer L; Kesselman, Dafna; Fisher, John P

2007-06-01

305

Pharmacokinetics and drug interactions of eslicarbazepine acetate.  

PubMed

Eslicarbazepine acetate (ESL) is a novel once-daily antiepileptic drug (AED) approved in Europe since 2009 that was found to be efficacious and well tolerated in a phase III clinical program in adult patients with partial onset seizures previously not controlled with treatment with one to three AEDs, including carbamazepine (CBZ). ESL shares with CBZ and oxcarbazepine (OXC) the dibenzazepine nucleus bearing the 5-carboxamide substitute, but is structurally different at the 10,11 position. This molecular variation results in differences in metabolism, preventing the formation of toxic epoxide metabolites such as carbamazepine-10,11-epoxide. Unlike OXC, which is metabolized to both eslicarbazepine and (R)-licarbazepine, ESL is extensively converted to eslicarbazepine. The systemic exposure to eslicarbazepine after ESL oral administration is approximately 94% of the parent dose, with minimal exposure to (R)-licarbazepine and OXC. After ESL oral administration, the effective half-life (t(1/2,eff) ) of eslicarbazepine was 20-24 h, which is approximately two times longer than its terminal half-life (t(1/2)). At clinically relevant doses (400-1,600 mg/day) ESL has linear pharmacokinetics (PK) with no effects of gender or moderate liver impairment. However, because eslicarbazepine is eliminated primarily (66%) by renal excretion, dose adjustment is recommended for patients with renal impairment. Eslicarbazepine clearance is induced by phenobarbital, phenytoin, and CBZ and it dose-dependently decreases plasma exposure of oral contraceptive and simvastatin. PMID:22612290

Bialer, Meir; Soares-da-Silva, Patricio

2012-06-01

306

UVB photolysis of hydrocortisone 21-acetate.  

PubMed

Hydrocortisone 21-acetate (HCA) in methanol solution undergoes photodegradation under UVB light, as monitored by HPLC. Five main photoproducts have been isolated and characterized by means of NMR and mass spectroscopy. One of them derives from a Norrish I photoreaction which cleaves the C17-C20 bond of the steroid yielding the andro-derivative, a second product comes from a Yang-type photorearrangement which links C18 to C20 yielding a cyclobutane adduct. The former photoproduct, in turn, undergoes further photolysis giving rise to various photoproducts, of which three have been characterized. The first is a stereoisomer of the andro-derivative, the others arise from the opening of the five-membered ring. HCA also proved photounstable in the solid state and in a commercial formulation for topical use, thus confirming the requirements of the Pharmacopeias for light protection of this drug. Indeed, experiments on LPS-stimulated THP-1 cells demonstrated the loss of anti-inflammatory activity when HCA was UVB-photodegraded. The radical mechanism involved in HCA photolysis seems also responsible for the in vitro photohemolytic effect and lipid peroxidation induced by HCA in combination with UVB light. PMID:18423938

Caffieri, Sergio; Dall'Acqua, Stefano; Castagliuolo, Ignazio; Brun, Paola; Miolo, Giorgia

2008-08-01

307

Anaerobic digestion of starch-polyvinyl alcohol biopolymer packaging: biodegradability and environmental impact assessment.  

PubMed

The digestibility of a starch-polyvinyl alcohol (PVOH) biopolymer insulated cardboard coolbox was investigated under a defined anaerobic digestion (AD) system with key parameters characterized. Laboratory results were combined with industrial operational data to develop a site-specific life cycle assessment (LCA) model. Inoculated with active bacterial trophic groups, the anaerobic biodegradability of three starch-PVOH biopolymers achieved 58-62%. The LCA modeling showed that the environmental burdens of the starch-PVOH biopolymer packaging under AD conditions on acidification, eutrophication, global warming and photochemical oxidation potential were dominated by atmospheric emissions released from substrate degradation and fuel combustion, whereas energy consumption and infrastructure requirements were the causes of abiotic depletion, ozone depletion and toxic impacts. Nevertheless, for this bio-packaging, AD of the starch-PVOH biopolymer combined with recycling of the cardboard emerged as the environmentally superior option and optimization of the energy utilization system could bring further environmental benefits to the AD process. PMID:22001054

Guo, M; Trzcinski, A P; Stuckey, D C; Murphy, R J

2011-12-01

308

Polyvinyl alcohol from China, Japan, Korea, and Taiwan. Export trade information  

SciTech Connect

On the basis of the record developed in the subject investigations, the Commission unanimously determines, pursuant to section 733(a) of the Tariff Act of 1930 (19 U.S.C. Section 1673b(a)), that there is a reasonable indication that an industry in the United States is materially injured by reason of imports from China, Japan, and Taiwan of polyvinyl alcohol, provided for a subheading 3905.20.00 of the Harmonized Tariff Schedule of the United States, that are alleged to be sold in the United States at less than fair value (LTFV). Investigation No. 731-TA-728 (Preliminary) concerning Korea is terminated on the basis of the unanimous determination that imports from Korea are negligible.

NONE

1995-04-01

309

PIXE investigation of in vitro release of chloramphenicol across polyvinyl alcohol/acrylamide hydrogel  

NASA Astrophysics Data System (ADS)

Hydrogels based on polyvinyl alcohol and different amounts of acrylamide monomer were prepared by thermal cross-linking in the solid state. The hydrogels were investigated for drug delivery system applications. Chloramphenicol was adopted as a model drug to study its release behavior. Particle induced X-ray emission was utilized to study the drug release behavior across the hydrogels and a comparison study with ultraviolet measurements was performed. Fourier Transform Infrared measurements were carried out for molecular characterization. The releasing behavior of the drug exhibits a decrease and a subsequent increase in the release rate, as the acrylamide monomer increases. Characterization of the hydrogels has shown a competitive behavior between crosslinking with AAm acrylamide monomer or oligomerized version, depending on the amount added to prepare the hydrogels.

Rihawy, M. S.; Alzier, A.; Allaf, A. W.

2011-09-01

310

Advances in polyvinyl alcohol hydrogel keratoprostheses: protection against ultraviolet light and fabrication by a molding process.  

PubMed

Our goal was to: 1) modify poly(vinyl alcohol) hydrogels intended for use in a synthetic cornea to absorb ultraviolet light and 2) develop molding procedures for the fabrication of the device. Two ultraviolet light-absorbing monomers were incorporated by copolymerization. The resulting hydrogels protected against ultraviolet light, were not toxic to corneal fibroblasts, and the protection did not diminish during prolonged aqueous exposure. A novel keratoprosthesis molding procedure was developed that made use of the phase transition properties of mixtures of poly(vinyl-trifluoroacetate) and acetonitrile. In this procedure the keratoprosthesis was shaped and a fibrous skirt was bonded to it in a single operation. Composite keratoprostheses were designed and prepared for in vivo testing. PMID:9086399

Tsuk, A G; Trinkaus-Randall, V; Leibowitz, H M

1997-03-01

311

Hydroxyapatite nanoparticles: electrospinning and calcination of hydroxyapatite/polyvinyl butyral nanofibers and growth kinetics.  

PubMed

Electrospinning of hydroxyapatite (HA)/polyvinyl butyral solution resulted in the formation of fibers with average diameter of 937-1440 nm. These fibers were converted into HA nanoparticles with size <100 nm after undergoing calcination treatment at 600°C. The diameter of the fiber was found to be influenced by applied voltage and spinning distance. The injection flowrate did not affect the diameter significantly. The electrospinning method successfully reduced the commercial HA particle size in the range of 400-1100 nm into <100 nm. The dispersion of the finally calcined HA nanoparticles was improved significantly after anionic sodium dodecyl sulfate surfactant was introduced. The experimental data of HA growth kinetics were subjected to the integral method of analysis, and the rate law of the reaction was found to follow the first order reaction. PMID:23225849

Zakaria, Siti Maisurah; Sharif Zein, Sharif Hussein; Othman, Mohd Roslee; Jansen, John A

2013-07-01

312

Improvement of polyvinyl alcohol properties by adding nanocrystalline cellulose isolated from banana pseudostems.  

PubMed

Cellulose nanocrystals (CNCs) isolated from banana pseudostems fibers (BPF) of the Pacovan variety were used as fillers in a polyvinyl alcohol (PVOH) matrix to yield a nanocomposite. The fibers from the external fractions of the BPF were alkaline bleached and hydrolyzed under acidic conditions (H2SO4 62% w/w, 70 min, 45 °C) to obtain CNCs with a length (L) of 135.0 ± 12.0 nm and a diameter (D) of 7.2 ± 1.9 nm to yield an aspect ratio (L/D) of 21.2. The CNCs were applied to PVOH films at different concentrations (0%, 1%, 3%, and 5% w/w, dry basis). With higher concentrations of CNCs, the water-vapor barrier of the films increased, while the optical properties changed very little. Increasing the concentration of the CNCs up to 3% significantly improved the mechanical properties of the nanocomposite. PMID:25129731

Pereira, André Luís S; do Nascimento, Diego M; Souza Filho, Men de Sá M; Morais, João Paulo S; Vasconcelos, Niedja F; Feitosa, Judith P A; Brígida, Ana Iraidy S; Rosa, Morsyleide de F

2014-11-01

313

Biodegradation of polyvinyl alcohol by a brown-rot fungus, Fomitopsis pinicola.  

PubMed

A brown-rot fungus, Fomitopsis pinicola, degraded polyvinyl alcohol (PVA) in quartz sand but not in liquid culture. From gel permeation chromatography analysis, the high-molecular-weight fraction of PVA was decreased by the action of F. pinicola but the coloration of the culture filtrate with I2 solution increased. The reason for the increase in coloration was assumed to be the increase in the low-molecular-weight fraction in degraded PVA. Diffuse reflectance infrared Fourier transform spectral analysis showed that spectral changes of the fungally degraded PVA were similar to those of PVA treated with Fenton's reagent suggesting that PVA degradation by F. pinicola was via the Fenton reaction. F. pinicola can thus be used to degrade PVA in woody wastes. PMID:23881320

Tsujiyama, S; Okada, A

2013-11-01

314

Electrospun polyvinyl alcohol-collagen-hydroxyapatite nanofibers: a biomimetic extracellular matrix for osteoblastic cells  

NASA Astrophysics Data System (ADS)

The failure of prosthesis after total joint replacement is due to the lack of early implant osseointegration. In this study polyvinyl alcohol-collagen-hydroxyapatite (PVA-Col-HA) electrospun nanofibrous meshes were fabricated as a biomimetic bone-like extracellular matrix for the modification of orthopedic prosthetic surfaces. In order to reinforce the PVA nanofibers, HA nanorods and Type I collagen were incorporated into the nanofibers. We investigated the morphology, biodegradability, mechanical properties and biocompatibility of the prepared nanofibers. Our results showed these inorganic-organic blended nanofibers to be degradable in vitro. The encapsulated nano-HA and collagen interacted with the PVA content, reinforcing the hydrolytic resistance and mechanical properties of nanofibers that provided longer lasting stability. The encapsulated nano-HA and collagen also enhanced the adhesion and proliferation of murine bone cells (MC3T3) in vitro. We propose the PVA-Col-HA nanofibers might be promising modifying materials on implant surfaces for orthopedic applications.

Song, Wei; Markel, David C.; Wang, Sunxi; Shi, Tong; Mao, Guangzhao; Ren, Weiping

2012-03-01

315

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

PubMed

This paper presents a novel and facile method for the generation of efficient antibacterial coatings which can be applied to practically any type of substrate. Silver nanoparticles were stabilized with an adsorbed surface layer of polyvinyl sulphonate (PVS). This steric layer provided excellent colloidal stability, preventing aggregation over periods of months. PVS-coated silver nanoparticles were bound onto amine-containing surfaces, here produced by deposition of an allylamine plasma polymer thin film onto various substrates. SEM imaging showed no aggregation upon surface binding of the nanoparticles; they were well dispersed on amine surfaces. Such nanoparticle-coated surfaces were found to be effective in preventing attachment of Staphylococcus epidermidis bacteria and also in preventing biofilm formation. Combined with the ability of plasma polymerization to apply the thin polymeric binding layer onto a wide range of materials, this method appears promising for the fabrication of a wide range of infection-resistant biomedical devices. PMID:20431209

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

2010-05-28

316

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

NASA Astrophysics Data System (ADS)

This paper presents a novel and facile method for the generation of efficient antibacterial coatings which can be applied to practically any type of substrate. Silver nanoparticles were stabilized with an adsorbed surface layer of polyvinyl sulphonate (PVS). This steric layer provided excellent colloidal stability, preventing aggregation over periods of months. PVS-coated silver nanoparticles were bound onto amine-containing surfaces, here produced by deposition of an allylamine plasma polymer thin film onto various substrates. SEM imaging showed no aggregation upon surface binding of the nanoparticles; they were well dispersed on amine surfaces. Such nanoparticle-coated surfaces were found to be effective in preventing attachment of Staphylococcus epidermidis bacteria and also in preventing biofilm formation. Combined with the ability of plasma polymerization to apply the thin polymeric binding layer onto a wide range of materials, this method appears promising for the fabrication of a wide range of infection-resistant biomedical devices.

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

2010-05-01

317

Characterization of a macroporous polyvinyl alcohol scaffold for the repair of focal articular cartilage defects  

PubMed Central

Focal cartilage defects reduce the ability of articular cartilage to resist mechanical loading and provide lubrication during joint motion. The limitations in current surgical treatments have motivated the use of biocompatible scaffolds as a future treatment option. Here we describe a second-generation, macroporous, polyvinyl alcohol (PVA) scaffold with independently tunable morphological and mechanical properties. The compressive moduli of the PVA scaffold increased with increasing polymer concentration and applied compressive strain, with values in the range for human articular cartilage (HA >1000 kPa, EY >500 kPa). Scaffolds also possessed strain-dependent permeability and Poisson’s ratio. The interconnected macroporous network was found to facilitate chondrocyte seeding and proliferation through the scaffold over 1 week in culture. Overall, these promising characteristics demonstrate the potential of this macroporous scaffold for future studies in focal cartilage defect repair. PMID:22549901

Ng, Kenneth W.; Torzilli, Peter A.; Warren, Russell F.; Maher, Suzanne A.

2013-01-01

318

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

PubMed

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

Nelson, J D; Farris, R L

1988-04-01

319

Studying the activity of antitubercluosis drugs inside electrospun polyvinyl alcohol, polyethylene oxide, and polycaprolacton nanofibers.  

PubMed

The activity of antituberculosis drugs (streptomycin sulfate, isoniazid, pyrazinamid, and clarithromycin) embedded in biodegradable nanofibers against Mycobacterium avium has been studied by broth dilution assay and by agar plate assay. These drugs have also been embedded in electrospun polyvinyl alcohol (PVA), polyethylene oxide (PEO), and polycaprolacton (PCL) nanofibers to design a new single tablet containing first-line antituberculosis drugs. Our results show that antituberculosis drugs are active at tiny amounts (up to 300 µg mL(-1) of solvent). However, within polymer matrices, high amounts of drugs are required to avoid unwanted weak interactions within PEO and PCL matrices. The successful design of a single tablet containing required amounts of antituberculosis drugs is essential for the full treatment of tuberculosis in patients with HIV. PMID:24376010

Hassounah, Ibrahim Anwar; Shehata, Nader Abdelmonem; Kimsawatde, Gade Carolyn; Hudson, Amanda Gayle; Sriranganathan, Nammalwar; Joseph, Eugene Gregory; Mahajan, Roop L

2014-11-01

320

Highly reflective and adhesive surface of aluminized polyvinyl chloride film by vacuum evaporation  

NASA Astrophysics Data System (ADS)

Aluminized poly(vinyl chloride) (PVC) film with high reflectivity and strong adhesion was facilely fabricated by vacuum evaporation. The technical study revealed that both alkali-pretreatment of the PVC matrix and thermal annealing after aluminization could greatly promote the peeling adhesion force of this metal/polymer composite by producing interfacial active chemical groups and removing the inner stress, respectively. Reflectivity test and AFM study indicated that the reflecting capacitance of the aluminum coating was closely related to the surface roughness, which can be easily controlled by modulating deposition of aluminum. Moreover, the formation of aluminum layer follows an island model process, and a continuous and smooth coating with highest reflectivity and lowest surface resistance was achieved at deposition time of 60 s. We anticipate that the cost-effective metallized PVC film by this strategy may find extensive applications in light harvesting, solar energy, and flexible mirrors, among others.

Li, Denian; Tai, Qile; Feng, Qiang; Li, Qi; Xu, Xizhe; Li, Hairong; Huang, Jing; Dong, Lijie; Xie, Haian; Xiong, Chuanxi

2014-08-01

321

Polyvinyl chloride plastics in municipal solid waste combustion. Impact upon dioxin emissions: A synthesis of views  

SciTech Connect

This report examines the issue of whether the polyvinyl chloride (PVC) plastics content of municipal solid waste (MSW) is a significant contributor to emissions of chlorinated dibenzo-p-dioxins (dioxins) that are associated with MSW combustion. Indications based on a consideration of this issue are developed through a synthesis of available information. While there is convincing experimental evidence that various conditions can cause production of dioxins when PVC is thermally treated, a fundamental issue that remains to be solved is how these findings relate to operating conditions that are characteristic of well designed, maintained and operated MSW combustion facilities, equipped with modern air pollution controls. These findings largely have been derived from laboratory or pilot scale experimentation and from full-scale studies that have carried out at facilities of varying design and purpose.

Not Available

1993-04-01

322

Dielectric investigations and ac conductivity of polyvinyl alcohol films doped with europium and terbium chloride  

NASA Astrophysics Data System (ADS)

Differential scanning calorimetry (DSC) was used to identify the phase transitions of polyvinyl alcohol (PVA) doped with europium chloride (EuCl 3) and terbium chloride (TbCl 3). The dielectric constant and the loss tangent behavior of the investigated samples were studied as a function of temperature in the frequency range 1-100 kHz. The detailed analysis of the results showed that dielectric dispersion consists of both dipolar and interfacial polarization. The temperature coefficient of permittivity (TCP) and the electrical dipole moment ( ?) were calculated. Also, the activation energy for the glass relaxation process from the dielectric loss tangent measurements was calculated. Measurements of the ac conductivity as a function of frequency at different temperatures indicated that the correlated barrier hopping (CBH) model is the most suitable mechanism for the ac conduction behavior. The ac parameters, such as hopping distance ( R, Rmin), polaron binding energy ( UM) and Coulombic barrier height ( Uh) were calculated.

Abd El-kader, F. H.; Osman, W. H.; Mahmoud, K. H.; Basha, M. A. F.

2008-10-01

323

Polyvinyl pyridine metal complex as permanent antimicrobial finishing for viscose fabric.  

PubMed

Viscose fabrics were treated with polyvinyl pyridine (PVP) using padding technique, followed by oxidation with hydrogen peroxide or peracetic acid, which was prepared by the reaction of tetra acetyl ethylene diamine (TAED) with hydrogen peroxide. Peracetic acid gives higher oxidation of PVP than hydrogen peroxide. FTIR study proved the formation of N-oxide as a result of oxidation. Incorporation of copper and silver ion onto oxidized PVP was also proved by FTIR. The antimicrobial study emphasise that Cu/oxidized PVP and Ag/oxidized PVP have retarded the growth of bacteria significantly, and Ag/oxidized PVP has a far better biocidal activity. The antibacterial activity of both metal ions survived after washing 10 times. PMID:18835405

Kantouch, A; El-Sayed, A Atef

2008-12-01

324

Reverse osmosis performance of modified polyvinyl alcohol thin-film composite membranes  

SciTech Connect

Membrane separation characteristics in the nanofiltration (NF) and reverse osmosis (RO) regions of the filtration spectrum are governed by a complex combination of both steric hindrance and surface force interactions. NF and RO membranes having surface charges show unusual selectivity behavior not predicted on the basis of physical pore size alone. Hence, practical characterizations should employ techniques to gain insight on membrane function. In this work, the separation characteristics of an anionically charged modified polyvinyl alcohol (PVA) thin-film composite membrane under different operating pressures were investigated. A qualitative measurement of the surface force interactions between solutes and membrane polymer was conducted using liquid chromatography technique. An attempt was also made to study the chlorine resistance of the composite membrane.

Lang, K.; Chowdhury, G.; Matsuura, T.; Sourirajan, S. (Univ. of Ottawa, Ontario (Canada))

1994-08-01

325

Formation of copper centers in a sensitized zinc oxide-polyvinyl alcohol system  

SciTech Connect

A substantial drop in the use of silver by the photographic industry may be brought about by replacing the conventional silver halides with low-silver and silver-free photographic materials. Of the silver-free photosensitive layers the most comparable to silver halogens in ultraviolet sensitivity is one comprising a dispersion of zinc oxide powder in polyvinyl alcohol (PVA), sensitized by components of a copper physical developer. This paper reports methods for forming latent image centers in a zinc oxide-PVA system sensitized by components of a copper physical developer. The derivatographic analysis was carried out on a Paulik Derivatograph. Electron spin resonance spectra were taken on a Bruker spectrometer at 77 K.

Gerleman, N.G.; Osipov, D.P.; Shagisultanova, G.A.

1988-11-10

326

In vitro characterization of polyvinyl alcohol assisted hydroxyapatite derived by sol-gel method.  

PubMed

The synthesis and characterization of sol-gel derived hydroxyapatite (HAp) were investigated with the effects of the addition of polyvinyl alcohol (PVA) to the structural and material in vitro behavior. All samples were soaked in simulated body fluid (SBF) for 14 and 28 days. The characterization of bioceramics before and after immersing in SBF was carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, differential thermal analysis (DTA), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. After the simulated body fluid period, the crystal structure and phase of HAp samples did not change significantly. The characteristic bands of hydroxyl, phosphate and carbonate groups were detected. HAp exhibited a thermal stability of room temperature to 1000 °C. The surface morphologies of the samples show an evident change with the soaking period in SBF. PMID:24411374

Kaygili, Omer; Keser, Serhat; Al Orainy, R H; Ates, Tankut; Yakuphanoglu, Fahrettin

2014-02-01

327

Structural dependence of silver nanowires on polyvinyl pyrrolidone (PVP) chain length.  

PubMed

The effect of the chain length of polyvinyl pyrrolidone (PVP) on the structures of silver nanowires (AgNWs) is explored in this study. It was found in the experiments that PVP, when serving as a capping agent, has a great impact on the morphology and structure of AgNWs. By means of a series of experiments and the inquiry of the growth mechanism, the critical minimum PVP chain length for the successful formation of uniform nanowires was discovered, below which only nanoparticles or short nanorods can be obtained. Surprisingly, a core-shell structure of a nanowire with a polycrystal was observed when PVP with a very long chain length was employed in the processing. PMID:25407502

Zeng, Xiping; Zhou, Bingpu; Gao, Yibo; Wang, Cong; Li, Shunbo; Yeung, Chau Yeung; Wen, WeiJia

2014-12-12

328

Method of cross-linking polyvinyl alcohol and other water soluble resins  

NASA Technical Reports Server (NTRS)

A self supporting sheet structure comprising a water soluble, noncrosslinked polymer such as polyvinyl alcohol which is capable of being crosslinked by reaction with hydrogen atom radicals and hydroxyl molecule radicals is contacted with an aqueous solution having a pH of less than 8 and containing a dissolved salt in an amount sufficient to prevent substantial dissolution of the noncrosslinked polymer in the aqueous solution. The aqueous solution is then irradiated with ionizing radiation to form hydrogen atom radicals and hydroxyl molecule radicals and the irradiation is continued for a time sufficient to effect crosslinking of the water soluble polymer to produce a water insoluble polymer sheet structure. The method has particular application in the production of battery separators and electrode envelopes for alkaline batteries.

Phillipp, W. H.; May, C. E.; Hsu, L. C.; Sheibley, D. W. (inventors)

1980-01-01

329

Structural, thermal and electrochemical cell characteristics of poly(vinyl chloride)-based polymer electrolytes  

NASA Astrophysics Data System (ADS)

A study is made of a polymer electrolyte system composed of poly(vinyl chloride) (PVC) as a host polymer, lithium tetrafluoroborate (LiBF 4) and lithium triflate (LiCF 3SO 3) as salts and a mixture of ethylene carbonate and propylene carbonate as plasticizers. X-ray diffraction (XRD) reveales that the salts and plasticizers disrupt the crystalline nature of PVC-based polymer electrolytes and converts them into an amorphous phase. Differential scanning calorimetry studies suggest that the plasticized samples have lower values of the glass tranisition temperature Tg, and thermogravimetric studies show that the thermal stability of the polymer electrolytes decreases with addition of plasticizers. The plasticized PVC electrolyte is used in the fabrication of electrochemical cells. The open-circuit voltage, discharge time for the plateau region, etc. are evaluated.

Ramesh, S.; Arof, A. K.

330

[Material labeling of soft plastic toys and plasticizers in polyvinyl chloride products].  

PubMed

We investigated the labeling and content of plasticizers of soft plastic toys. First, we investigated material labeling in 96 products purchased in fiscal years 2000 and 2001. Among these products, 43% of those purchased in fiscal 2000 and 68% of those purchased in fiscal 2001 were labeled. We then investigated the kinds and amounts of plasticizers in 73 soft polyvinyl chloride (PVC) toys. Three kinds of phthalates and six other kinds of plasticizers were detected in the soft PVC toys. Diisononyl phthalate, di(2-ethylhexyl) phthalate, diisononyl adipate, and O-acetyl tributyl citrate were detected at high frequency, and in large amounts. The average total content of all plasticizers was 280 mg/g for the products purchased in fiscal 2000 and 227 mg/g for those in fiscal 2001. In fiscal 2001, antioxidants, 4-nonylphenol, and bisphenol A were investigated in addition to plasticizers. PMID:12968472

Abe, Yukiko; Sugita, Takiko; Wakui, Chiseko; Niino, Tatsuhiro; Yomota, Chikako; Ishiwata, Hajimu; Tanamoto, Ken-ichi; Maitani, Tamio

2003-06-01

331

Nanofabrication with water-dissolvable polymer masks of polyvinyl alcohol (PVA): MxL  

NASA Astrophysics Data System (ADS)

The paper describes the use of water-dissolvable masks, formed from a polyvinyl alcohol film forming solution, for high-resolution pattern definition and materials-transfer printing. The approach replicates surface patterns as water-soluble polymer masks (templates) by spin-casting the film-forming solution onto a master pattern. The water-soluble mask is coupled to a substrate by polymer adhesion to form a solid two-layer structure. Water is used to dissolve the mask layer to uncover the formed pattern in the adhesive layer, thereby providing a new release mechanism for contact-based methods of pattern formation. Moreover, the patterned polymer adhesion transfer process enables a large-area, conformable, single-use template addressed towards meeting registration and defect control challenges in contact printing. The process further incorporates the capability to replicate with loaded nanostructured materials to form a composite of nanoparticles in a soluble polymeric matrix with a patterned surface. The embedded particles are accessible at the surface of the template and thereby are concurrently transferred to the substrate through the polymer adhesion process and subsequently released from the soluble template after water-dissolution in a structured manner. The paper also describes applications of PVA in forming polymer masks as (a) suspended thin-film templates, (b) imprinting templates for repeated use, and (c) as templates for nanoparticle formation by collimated deposition. Polyvinyl alcohol thus provides an additional material for consideration as a mask (template) for nanofabrication, and would be an alternative to quartz, silicon, and polydimethylsiloxane (PDMS) in that regard. The class of printing techniques using PVA as a mask material is referred to as molecular transfer lithography (MxL).

Schaper, Charles D.

2004-05-01

332

76 FR 32366 - Determination That ORLAAM (Levomethadyl Acetate Hydrochloride) Oral Solution, 10 Milligrams...  

Federal Register 2010, 2011, 2012, 2013

...Levomethadyl Acetate Hydrochloride) Oral Solution, 10 Milligrams/Milliliter, Was Not...acetate hydrochloride (HCl)) oral solution, 10 milligrams (mg)/milliliter...ANDAs) for levomethadyl acetate HCl oral solution, 10 mg/mL, if all other legal...

2011-06-06

333

Water dispersible microbicidal cellulose acetate phthalate film  

PubMed Central

Background Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production. Methods CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined. Results The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ?50 to ?65% ethanol (EtOH). The films are ?100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold. Conclusions Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP. PMID:14617380

Neurath, A Robert; Strick, Nathan; Li, Yun-Yao

2003-01-01

334

Clostridiumm ljungdahlii, an anaerobic ethanol and acetate producing microorganism  

DOEpatents

A newly discovered microorganism was isolated in a biologically pure culture and designated Clostridium ljungdahlii, having the identifying characteristics of ATCC No. 49587. Cultured in an aqueous nutrient medium under anaerobic conditions, this microorganism is capable of producing ethanol and acetate from CO and H.sub.2 O and/or CO.sub.2 and H.sub.2 in synthesis gas. Under optimal growth conditions, the microorganism produces acetate in preference to ethanol. Conversely, under non-growth conditions, ethanol production is favored over acetate.

Gaddy, James L. (Fayetteville, AR); Clausen, Edgar C. (Fayetteville, AR)

1992-01-01

335

The medical and metabolic consequences of administration of sodium acetate.  

PubMed

1. The standard total parenteral nutrition, peritoneal dialysis, hemodialysis and many surgical fluids in use today contain 36 to 45 mM D,L-lactate or 2 to 140 mM acetate whereas the normal blood level of D-lactate is 0.02 mM L-lactate 0.5 to 5 mM and acetate 0.1 nM. The reasons for the continued use in patients of such unphysiological concentrations of these anions appear to be historic. 2. Administration of similar concentrations of these anions to the rat causes widespread metabolic disturbances which mimic many of the untoward complications associated with current parenteral and dialysis therapy. Understanding of the mechanisms attendant upon the metabolism of these anions may serve as a guide for designing improved parenteral fluids for human patients. 3. Elevation of blood D-lactate to 5 mM is associated with cerebral dysfunction in human patients. 4. Acetate stimulates the release of the inflammatory leukokine, interleukin-1 from human monocytes. Use of 35 to 45 mM acetate in peritoneal dialysis fluids led to peritoneal fibrosis. Patients exposed to acetate containing hemodialysis fluids have 12-fold elevation in their plasma interleukin-1 levels. 5. Administration of 20 mM sodium acetate to rats leads to a number of metabolic disturbances similar to those seen in human dialysis patients: (a) Acetate elevates blood glucose in the rat and may contribute to the exacerbation of the carbohydrate intolerance seen in uremic patients. (b) Acetate increases the levels of hepatic malonyl CoA, the rate controlling substrate of fatty acid synthesis and may exacerbate the hypertriglyceridemia characteristic of dialysis patients. (c) Acetate administration in the rat leads to a decrease in the cytosolic phosphorylation potential, reduction of the redox state of the free cytosolic NAD couple and paradoxical oxidation of the mitochondrial NAD couple in a pattern analogous to that produced by uncouplers of oxidative phosphorylation and may account in part for the elevation of temperature reported in patients undergoing hemodialysis with acetate. (d) Acetate administration in the rat leads to an increase in intracellular phosphorylated intermediates, adenine nucleotides, inorganic phosphate, inorganic pyrophosphate, calcium and magnesium. On cessation of acetate metabolism, the inorganic phosphate and calcium accumulated intracellularly leave the intracellular space. In patients undergoing hemodialysis, the blood phosphate returns to predialysis levels, within 6 hr after the completion of treatment, leaving significant numbers of patients with chronic hyperphosphatemia and the multiple complications attendant to that state.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2854950

Veech, R L; Gitomer, W L

1988-01-01

336

The antibacterial activity and stability of acetic acid.  

PubMed

Acetic acid has been shown to have good antibacterial activity against micro-organisms such as Pseudomonas aeruginosa. This study examined the activity against a range of bacterial pathogens and also assessed any reduction in antibacterial activity due to evaporation or inactivation by organic material in dressings. Acetic acid was active at dilutions as low as 0.166% and the activity was not reduced by evaporation nor by inactivation by cotton swabs. Burn injuries are a major problem in countries with limited resources. Acetic acid is an ideal candidate for use in patients who are treated in those parts of the world. PMID:23747099

Fraise, A P; Wilkinson, M A C; Bradley, C R; Oppenheim, B; Moiemen, N

2013-08-01

337

SAXS investigation on aggregation phenomena in supercritical \\chem{CO2}  

NASA Astrophysics Data System (ADS)

Synchrotron Small-Angle X-Ray scattering (SAXS) measurements on aggregate formation of a Polyvinyl acetate-b-Perfluoro octyl acrylate (PVAc-b-PFOA) block copolymer in supercritical CO{2} are here reported. Experiments were carried out for a series of different thermodynamic conditions, changing the solvent density by profiling both the pressure at constant temperature and the temperature at constant pressure. This block copolymer and in general fluorocarbon-hydrocarbon di-blocks form aggregates depending on the value of CO{2} density. A sharp transition between monomers dissolved as random coils and micelles characterized by a solvophilic shell and a solvophobic core occurs when the CO{2} density reaches a critical value. Results of critical micellization density (CMD) derived from pressure and temperature ramps experiment along with the comparison with previous SANS results are here reported to give additional experimental support to the solvent density-driven aggregation process.

Celso, F. Lo; Triolo, A.; Triolo, F.; Donato, D. I.; Steinhart, M.; Kriechbaum, M.; Amenitsch, H.; Triolo, R.

2002-06-01

338

N-Type Thermoelectric Performance of Functionalized Carbon Nanotube-Filled Polymer Composites  

PubMed Central

Carbon nanotubes (CNTs) were functionalized with polyethyleneimine (PEI) and made into composites with polyvinyl acetate (PVAc). CNTs were dispersed with different amounts of sodium dodecylbenzenesulfonate (SDBS) prior to the PEI functionalization. The resulting samples exhibit air-stable n-type characteristics with electrical conductivities as great as 1500 S/m and thermopowers as large as ?100 µV/K. Electrical conductivity and thermopower were strongly affected by CNT dispersion, improving the properties with better dispersion with high concentrations of SDBS. This improvement is believed to be due to the increase in the number of tubes that are evenly coated with PEI in a better-dispersed sample. Increasing the amount of PEI relative to the other constituents positively affects thermopower but not conductivity. Air exposure reduces both thermopower and conductivity presumably due to oxygen doping (which makes CNTs p-type), but stable values were reached within seven days following sample fabrication. PMID:23133605

Freeman, Dallas D.; Choi, Kyungwho; Yu, Choongho

2012-01-01

339

Impedance spectroscopy on dye-sensitized solar cells with a poly(ethylenedioxythiophene):poly(styrenesulfonate) counter electrolyte  

NASA Astrophysics Data System (ADS)

We have successfully fabricated the dye-sensitized solar cell (DSSC) devices using ruthenium complex dye, polymer electrolytes, and poly(ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT: PSS) as a counter electrode. The overall power conversion efficiencies of the devices using polyethylene oxide (PEO), polyethylene glycol (PEG), polymethylmethacrylate (PMMA), and polyvinyl acetate (PVAc) as polymer electrolytes were 4.08%, 3.87%, 0.49%, and 0.20%, respectively, while the efficiencies of DSSC devices using Pt counter electrodes showed similar values of 5.7 ± 0.1%. The differences in the efficiencies and the charge transfer resistances (R CT ) of the DSSCs with various polymer electrolytes and counter electrodes were measured by using an electrochemical impedance analyzer (EIS) and are discussed.

Kim, Young-Keun; Park, Sung-Hae; Hwang, Won-Pill; Seo, Min-Hye; Park, Hyun-Woo; Jang, Young-Wook; Kim, Mi-Ra; Lee, Jin-Kook

2012-06-01

340

Water transport in cement-in-polymer dispersions at variable temperature studied by magnetic resonance imaging  

SciTech Connect

The hydration of recently developed cement-in-polymer dispersions (c/p) containing 30% and 40% poly (vinyl acetate) [PVAc] and 30% poly(vinyl alcohol) [PVA] was monitored on-line at various temperatures using {sup 1}H Single Point Imaging (SPI). The physical changes undergone by the materials as well as the complex manner in which the absorption process takes place and the evolution of the spin density were characterized and were found to be strongly dependent on the nature and amount of polymer and on the temperature. Based on the results obtained we propose a simple mathematical model which can be used to characterize the behaviour of the c/p dispersions exposed to hydration at variable temperature.

Olaru, A.M., E-mail: aolaru@mc.rwth-aachen.de; Bluemich, B.; Adams, A., E-mail: aadams@mc.rwth-aachen.de

2013-02-15

341

21 CFR 524.1881 - Prednisolone acetate ophthalmic and topical dosage forms.  

Code of Federal Regulations, 2010 CFR

...Prednisolone acetate ophthalmic and topical dosage forms. 524.1881 Section...RELATED PRODUCTS OPHTHALMIC AND TOPICAL DOSAGE FORM NEW ANIMAL DRUGS ...Prednisolone acetate ophthalmic and topical dosage...

2010-04-01

342

Expedient synthesis of ?-(2-azaheteroaryl) acetates via the addition of silyl ketene acetals to azine-N-oxides.  

PubMed

A new and expedient synthesis of ?-(2-azaheteroaryl) acetates is presented. The reaction proceeds rapidly under mild conditions via the addition of silyl ketene acetals to azine-N-oxides in the presence of the phosphonium salt PyBroP. This procedure affords diverse ?-(2-azaheteroaryl) acetates which are highly desirable components/building blocks in molecules of pharmaceutical interest but are traditionally challenging to synthesize via contemporary methods. The reaction optimization and mechanism as well as a novel electronically enhanced PyBroP derivative are described. PMID:24885646

Londregan, Allyn T; Burford, Kristen; Conn, Edward L; Hesp, Kevin D

2014-06-20

343

40 CFR 721.3880 - Polyalkylene glycol substituted acetate.  

Code of Federal Regulations, 2010 CFR

...Significant New Uses for Specific Chemical Substances § 721.3880...substituted acetate. (a) Chemical substance and significant...to reporting. (1) The chemical substance identified generically...substance without providing risk notification as...

2010-07-01

344

A PROGESTOGEN (CHLORMADINONE ACETATE = CAP) FOR CYCLE CONTROL AND INFERTILITY  

E-print Network

A PROGESTOGEN (CHLORMADINONE ACETATE = CAP) FOR CYCLE CONTROL AND INFERTILITY TREATMENT IN THE MARE, CAP has been used for infertility treatments and cycle control in mares in Austria. In all indications

Paris-Sud XI, Université de

345

SOLVENT EXTRACTION OF WASTEWATERS FROM ACETIC-ACID MANUFACTURE  

EPA Science Inventory

Solvent extraction was evaluated as a potential treatment method for wastewaters generated during the manufacture of acetic acid. Possible goals for an extraction process were considered. For the wastewater samples studied, extraction appeared to be too expensive to be practical ...

346

Health and environmental effects profile for ethyl acetate  

SciTech Connect

The Health and Environmental Effects Profile for ethyl acetate was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency actions under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Both published literature and information obtained from Agency program office files were evaluated as they pertained to potential human-health, aquatic-life and environmental effects of hazardous-waste constituents. Ethyl acetate has been determined to be a systemic toxicant. The daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effect during a lifetime, for ethyl acetate is 0.9 mg/kg/day for oral exposure. The Reportable Quantity (RQ) value for ethyl acetate is 1000.

Not Available

1986-12-01

347

Health and environmental effects profile for 2-methoxyethanol acetate  

SciTech Connect

The Health and Environmental Effects Profile for 2-methoxyethanol acetate was prepared to support listings of hazardous constituents of a wide range of waste streams under Section 3001 of the Resource Conservation and Recovery Act (RCRA) and to provide health-related limits for emergency actions under Section 101 of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). Both published literature and information obtained from Agency program office files were evaluated as they pertained to potential human-health, aquatic-life and environmental effects of hazardous-waste constituents. 2-methoxyethanol acetate has been determined to be a systemic toxicant. The daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effect during a lifetime, for 2-methoxyethanol acetate is 0.002 mg/kg/day for inhalation exposure. The Reportable Quantity (RQ) value for 2-methoxyethanol acetate is 100.

Not Available

1987-04-01

348

Acetate-Dependent Mechanisms of Inborn Tolerance to Ethanol  

PubMed Central

Aims: To clarify the role of acetate in neurochemical mechanisms of the initial (inborn) tolerance to ethanol. Methods: Rats with low and high inborn tolerance to hypnotic effect of ethanol were used. In the brain region homogenates (frontal and parietal cortex, hypothalamus, striatum, medulla oblongata) and brain cortex synaptosomes, the levels of acetate, acetyl-CoA, acetylcholine (AcH), the activity of pyruvate dehydrogenase (PDG) and acetyl-CoA synthetase were examined. Results: It has been found that brain cortex of rats with high tolerance to hypnotic effect of ethanol have higher level of acetate and activity of acetyl-CoA synthetase, but lower level of acetyl-?CoA and activity of PDG. In brain cortex synaptosomes of tolerant rats, the pyruvate oxidation rate as well as the content of acetyl-CoA and AcH synthesis were lower when compared with intolerant animals. The addition of acetate into the medium significantly increased the AcH synthesis in synaptosomes of tolerant, but not of intolerant animals. Calcium ions stimulated the AcH release from synaptosomes twice as high in tolerant as in intolerant animals. Acetate eliminated the stimulating effect of calcium ions upon the release of AcH in synaptosomes of intolerant rats, but not in tolerant animals. As a result, the quantum release of AcH from synaptosomes in the presence of acetate was 6.5 times higher in tolerant when compared with intolerant rats. Conclusion: The brain cortex of rats with high inborn tolerance to hypnotic effect of ethanol can better utilize acetate for the acetyl-CoA and AcH synthesis, as well as being resistant to inhibitory effect of acetate to calcium-stimulated release of AcH. It indicates the metabolic and cholinergic mechanisms of the initial tolerance to ethanol. PMID:21349883

Zimatkin, Sergey M.; Oganesian, Nikolay A.; Kiselevski, Yury V.; Deitrich, Richard A.

2011-01-01

349

Existence of a Novel Liguid Phase in Methyl Acetate  

Microsoft Academic Search

For methyl acetate with a planar structure \\\\includegraphics{dummy.eps} in the molecule, a spin-lattice relaxation time (T1) and a specific volume were measured in the liquid phase. Methyl acetate has a liquid-liquid phase transition at -12°C at atmospheric pressure. The liquid phase is divided into two parts named as L1 and L2 corresponding as high and low temperature liquid phase, respectively.

Shunichi Kawanishi

1983-01-01

350

Cathodic Hydrogen Evolution from Aqueous Solutions of Acetic Acid  

Microsoft Academic Search

In continuation of the work on establishing hydrogen donors in the hydrogen evolution reaction from different acid molecules, cathodic evolution of hydrogen on silver is investigated from solutions of monobasic acetic acid with the aim to establish the origin of reduced hydrogen. Solutions of 0.2 M acetic acid with 0.2 M perchloric acid, neutralized to different pH values by NaOH,

V. Marinovi?; A. R. Despi?

2004-01-01

351

METABOLISM OF ACETATE BY SHEEP LIVER HOMOGE'NATES 1  

Microsoft Academic Search

The metabolism of acetate has been studied in sheep liver homogenates. ContraD- to previous reports, acetate was oxidized by fresh liver homogenates, and aeet3,l-CoA was oxidized by both fresh and frozen-stored liver homogenates in the presence of the eofaetors XAI) and earnitine. With these two eofactors, oxidation plateaus after 20-30 rain, unless a 4-ca,'bon TCX cycle acid, such as sueeinate,

E. D. MAYFIELD; AXD B. CONNOR JOHNSON

352

Permeability of cellulose acetate membranes to selected solutes  

Microsoft Academic Search

The permeability of cellulose 2.5-acetate films to several electrolytes and nonelectrolytes was measured. Permeabilities were determined by a desorption-rate method in which diffusion and distribution coefficients were measured. The rejection of the same solutes by modified cellulose acetate membranes in reverse osmosis experiments was also measured. A comparison was made between intrinsic water and solute permeabilities and the reverse osmosis

H. K. Lonsdale; B. P. Cross; F. M. Graber; C. E. Milstead

1971-01-01

353

Acetalization of Carbonyl Compounds Catalyzed by I2-Doped Polyaniline  

Microsoft Academic Search

Polyaniline-I2 is prepared by doping of polyaniline base with iodine. Polyaniline base and polyaniline-I2 are characterized by infrared spectra, X-ray diffraction spectra, and thermogravimetric analysis. Polyaniline-I2 is used as a catalyst for the first time in acetalization of carbonyl compounds. The catalyzing acetalization of cyclohexanone and propane-1,2-diol is conducted in excellent yields with simple and more environmental benign procedure. This

Genxiang Luo; Miao He; Zhaojin Zhong

2008-01-01

354

Bacterial utilization of formic and acetic acid in rainwater  

NASA Astrophysics Data System (ADS)

Rain samples were collected aseptically, during 1983 and 1984, in Charlottesville, Virginia to determine the ability of bacteria in precipitation to utilize formate and acetate. The total number of bacteria, as counted by Acridine Orange Direct Counts, was one to two orders of magnitude greater from April to September (10 5 cells ml -1) than during the rest of the year (10 3-10 4 cells ml -1). Formate and acetate concentrations ranged between 6-23 and 3-9 ?M, respectively and were higher from June to September. Heterotrophic uptake on the day of collection was not different from the controls, but after incubation at room temperature for a minimum of three days, the turnover rate constants were 0.14 and 0.17 h -1 for formate and acetate, respectively. Total bacterial counts increased an order of magnitude during that interval. These turnover rate constants were used to calculate losses of 44 and 24 ?moll-1day-1 of formic and acetic acid, respectively. Turnover times were 1.5 and 34 days for formate and acetate, respectively. This study demonstrated that there are viable microorganisms in the atmosphere capable of utilizing formate and acetate for growth.

Herlihy, Linda Jolley; Galloway, James N.; Mills, Aaron L.

355

Proteome analysis of Acetobacter pasteurianus during acetic acid fermentation.  

PubMed

Acetic acid bacteria (AAB) are Gram-negative, strictly aerobic microorganisms that show a unique resistance to ethanol (EtOH) and acetic acid (AcH). Members of the Acetobacter and Gluconacetobacter genera are capable of transforming EtOH into AcH via the alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) enzymes and are used for the industrial production of vinegar. Several mechanisms have been proposed to explain how AAB resist high concentrations of AcH, such as the assimilation of acetate through the tricarboxylic acid (TCA) cycle, the export of acetate by various transporters and modifications of the outer membrane. However, except for a few acetate-specific proteins, little is known about the global proteome responses to AcH. In this study, we used 2D-DIGE to compare the proteome of Acetobacter pasteurianus LMG 1262(T) when growing in glucose or ethanol and in the presence of acetic acid. Interesting protein spots were selected using the ANOVA p-value of 0.05 as threshold and 1.5-fold as the minimal level of differential expression, and a total of 53 proteins were successfully identified. Additionally, the size of AAB was reduced by approximately 30% in length as a consequence of the acidity. A modification in the membrane polysaccharides was also revealed by PATAg specific staining. PMID:22155126

Andrés-Barrao, Cristina; Saad, Maged M; Chappuis, Marie-Louise; Boffa, Mauro; Perret, Xavier; Ortega Pérez, Ruben; Barja, François

2012-03-16

356

Effect of the polymer concentration on the ON/OFF states of a TN-LCD: polyvinyl alcohol vs. soy lecithin  

NASA Astrophysics Data System (ADS)

In this work we study the response of a Twisted Nematic Liquid Crystal Display (TN-LCD) by varying both the concentration and the polymer used for the microgroove. We compare the performance of two polymers: polyvinyl alcohol and soy lecithin. In particular, the light transmission for the ON/OFF states is evaluated. The polyvinyl alcohol is a polymer widely used in LCDs while lecithin soy is a natural polymer.

de Coss Martinez, Romeo; Gonzalez Murguia, Jose Luis

2011-03-01

357

Novel hydrogels of chitosan and poly(vinyl alcohol)-g-glycolic acid copolymer with enhanced rheological properties.  

PubMed

Poly(vinyl alcohol) (PVA) has been grafted with glycolic acid (GL), a biodegradable hydroxyl acid to yield modified poly(vinyl alcohol) (PVAGL). The formation of hydrogels at pH = 6.8 and physiological temperature through blending chitosan (CS) and PVAGL at different concentrations has been investigated. FTIR, DOSY NMR and oscillatory rheology measurements have been carried out on CS/PVAGL hydrogels and the results have been compared to those obtained for CS/PVA hydrogels prepared under the same conditions. The experimental results point to an increase in the number of interactions between chitosan and PVAGL in polymer hydrogels prepared with modified PVA. The resulting materials with enhanced elastic properties and thixotropic behavior are potential candidates to be employed as injectable materials for biomedical applications. PMID:24528729

Lejardi, A; Hernández, R; Criado, M; Santos, Jose I; Etxeberria, A; Sarasua, J R; Mijangos, C

2014-03-15

358

Solid–liquid equilibrium in the acetic acid–cyclohexane and acetic acid–trichloroacetic acid systems  

Microsoft Academic Search

Solid–liquid equilibrium in the binary systems acetic acid–cyclohexane and acetic acid–trichloroacetic acid was determined from time–temperature cooling and heating curves. The first system shows an eutectic point at x1?0.08 and T=271.9K. In the second system, a solid compound (1:1) was found and an equilibrium constant of the compound dissociation was calculated.

I Malijevská

2003-01-01

359

Immobilization of Anabaena azollae from Azolla filiculoides in polyvinyl foam for ammonia production in a photobioreactor system  

Microsoft Academic Search

Anabaena azollae (AS-DS), isolated from Azolla filiculoides and grown in nitrogen-free medium, was immobilized in 5-mm-cube polyvinyl foam pieces and incorporated into a photobioreactor system for the production of NH3. NH3 was produced continuously and in significant amounts. Benlate (methyl-1-butyl-carbamoyl)-2-benzimidazole carbamate at 5 ppm and l-methionine-d,l-sulphoximine at 50 µm stimulated NH3 production continuously for a period of 1 week.

S. Kannaiyan; K. K. Rao; D. O. Hall

1994-01-01

360

Immobilization of Anabaena azollae from Azolla filiculoides in polyvinyl foam for ammonia production in a photobioreactor system.  

PubMed

Anabaena azollae (AS-DS), isolated from Azolla filiculoides and grown in nitrogen-free medium, was immobilized in 5-mm-cube polyvinyl foam pieces and incorporated into a photobioreactor system for the production of NH3. NH3 was produced continuously and in significant amounts. Benlate (methyl-1-butyl-carbamoyl)-2-benzimidazole carbamate at 5 ppm and L-methionine-D,L-sulphoximine at 50 ?M stimulated NH3 production continuously for a period of 1 week. PMID:24420887

Kannaiyan, S; Rao, K K; Hall, D O

1994-01-01

361

Percutaneous right portal vein embolization with polyvinyl alcohol particles in gastric cancer metastasis: report of a case.  

PubMed

Polyvinyl alcohol (PVA) particles are used for the embolization of various vascular tumors. They are also used before hepatic resection to embolize the ipsilateral portal vein, causing hypertrophy of the remaining liver. We report our first experience with portal vein embolization (PVE) with PVA particles to treat gastric cancer metastasis to the liver. PVE with PVA is a safe interventional radiologic procedure, which does not cause problems during surgery and can improve the outcome of hepatic resection. PMID:16133672

Kutlu, Ramazan; Sarac, Kaya; Yilmaz, Sezai; Kirimlioglu, Vedat; Baysal, Tamer; Alkan, Alpay; Sigirci, Ahmet

2005-01-01

362

Radiation-chemical formation of hcl in poly(vinyl butyral) films containing chloral hydrate for use in radiation dosimetry  

Microsoft Academic Search

A new method for calculation of concentration of radiation-formed HCl in poly(vinyl butyral) (PVB) films containing chloral hydrate [CCl 3 CH(OH) 2 , 2,2,2-trichloroethane-1,1-diol] and acid-sensitive dye (thymol blue, TB), was developed. These plastic films undergo color change from yellow (the alkaline form of TB) to red (the acidic form of TB), indicating acid formation. The concentration of radiation-formed HCl

A. A. Abdel-Fattah; El-Sayed A. Hegazy; H. Ezz El-Din

2002-01-01

363

IR laser ablative and conventional decomposition of poly(vinyl phenyl ketone): Different processes and different products  

Microsoft Academic Search

Pulsed IR laser ablation of poly(vinyl phenyl ketone) results in the formation of CO, C1–C4 hydrocarbons, benzene, styrene and phenylacetylene and affords deposition of polymeric films that were examined by EDX-SEM, FTIR, UV and NMR spectroscopies and gel-permeation chromatography. It is revealed that the structure of the films is affected by laser fluence and their Mw distribution is almost identical

Dana Pokorná; Jan Šubrt; Anna Galíková; Josef Pola

2007-01-01

364

Effect of halide ions on the corrosion inhibition of mild steel in acidic medium using polyvinyl alcohol  

Microsoft Academic Search

Purpose – To investigate the effect of halide ions on the corrosion inhibition of mild steel using polyvinyl alcohol (PVA) in H2SO4 at 30-60°C and to study the mechanism of action. Design\\/methodology\\/approach – The corrosion rates were determined using the gravimetric (weight loss) and gasometric (hydrogen evolution) techniques. The results obtained in the absence and presence of PVA, halides, PVA

S. A. Umoren; O. Ogbobe; E. E. Ebenso; U. J. Ekpe

2006-01-01

365

Beam Damage of Poly(Vinyl Chloride) [PVC] Film as Observed by X-ray Photoelectron Spectroscopy  

SciTech Connect

XPS spectra of a spin-coated film poly(vinyl chloride) (PVC) were collected over a period of 243 minutes at 303 K to determine specimen damage during long exposures to monochromatic Al Ka x-rays. For this PVC film we measured the loss of chlorine as a function of time by rastering a focused 104.6 w 100 um diameter x-ray beam over a 1.4 mm x 0.2 mm area on the sample.

Engelhard, Mark H.; Krishna, Abhilash; Kulkarni, Pranita B.; Lee, Chi-Ying M.; Baer, Donald R.

2003-03-08

366

Surface analysis and peel strength of aged, oxygen-plasma-modified unplasticized poly(vinyl chloride) films  

Microsoft Academic Search

The surface of unplasticized poly(vinyl chloride) (UPVC) was modified by oxygen plasma treatment and analysed using X-ray photoelectron spectroscopy (XPS), contact angle analysis (CAA) and 180° peel test measurements. XPS results show a surface rich in oxygen-containing species which are detectable on the surface after 10 weeks following plasma treatment. CAA results, however, indicate that an initial increase in surface

M. Babai-Cline; J. P. Wightman

1995-01-01

367

Residual polyvinyl alcohol associated with poly ( d, l-lactide-co-glycolide) nanoparticles affects their physical properties and cellular uptake  

Microsoft Academic Search

Polyvinyl alcohol (PVA) is the most commonly used emulsifier in the formulation of poly lactide and poly (d,l-lactide-co-glycolide) (PLGA) polymeric nanoparticles. A fraction of PVA remains associated with the nanoparticles despite repeated washing because PVA forms an interconnected network with the polymer at the interface. The objective of this study was to determine the parameters that influence the amount of

Sanjeeb K Sahoo; Jayanth Panyam; Swayam Prabha; Vinod Labhasetwar

2002-01-01

368

Surface modification of poly(vinyl chloride) by physisorbed free radical initiation for reduced plasticizer migration and antimicrobial properties  

Microsoft Academic Search

Poly(vinyl chloride), PVC, is a particularly important commodity polymer that accounts for an annual world-wide production of 26 million tons. It is used frequently in the medical field as blood storage bags, endotracheal and dialysis tubing and intravenous catheters. Common plasticizers, namely di(2-ethylhexyl) phthalate (DEHP), are added to PVC to improve the processability and flexibility by lowering the glass transition

Kathryn McGinty

2008-01-01

369

Alkali doped polyvinyl alcohol\\/multi-walled carbon nano-tube electrolyte for direct methanol alkaline fuel cell  

Microsoft Academic Search

A novel route to functionalize polyvinyl alcohol (PVA) onto multi-walled carbon nano-tube (MWCNT) is reported in this work. FTIR, XPS, Raman spectroscopy, and TGA data confirmed PVA grafting onto the MWCNT. The grafted PVA content was estimated to be 25% in the PVA–functionalized MWCNT. A nano-composite consisting of PVA and 0.05% functionalized CNT was successfully prepared using a solution casting

Wen-Han Pan; S. Jessie Lue; Chia-Ming Chang; Ying-Ling Liu

2011-01-01

370

Effect of homogeneity on the thermal degradation of poly(vinyl chloride)\\/poly (?-methylstyrene-acrylonitrile-methylmethacrylate) blends  

Microsoft Academic Search

The thermal degradation of homogeneous and heterogeneous poly(vinyl chloride)\\/poly(?-methylstyrene-acrylonitrile-methylmethacrylate) (PVC\\/ MS-AN) blends were investigated by means of dynamic thermogravimetry. The blends were prepared by precipitation from solution in a common solvent (homogeneous PVC\\/MS-AN-MMA blend) and by pressing the mixture of solid polymers in a cold hydraulic press (heterogeneous PVC\\/MS-AN-MMA blend).From the thermogravimetric curves and by determining the kinetic parameters of

T. Kova?i?; B. Bari?; I. Klari?

1995-01-01

371

Poly(vinyl alcohol) hydrogels as hydrophilic matrices for the release of lipophilic drugs loaded in PLGA nanoparticles  

Microsoft Academic Search

Poly(vinyl alcohol) (PVA) hydrogels prepared by a freeze-thawing procedure were evaluated as matrices for the release of water-insoluble drugs such as dexamethasone. As it is impossible to directly entrap a lipophilic drug into a hydrophilic matrix, a novel mechanism has been designed based on producing biodegradable nanoparticles loaded with the drug, that could then be entrapped into the hydrogels. Nanoparticles

Maria Grazia Cascone; Zhouhai Zhu; Flavia Borselli; Luigi Lazzeri

2002-01-01

372

Lipogels: surface-adherent composite hydrogels assembled from poly(vinyl alcohol) and liposomes  

NASA Astrophysics Data System (ADS)

Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications.Drug-eluting engineered surface coatings are of paramount importance for many biomedical applications from implantable devices to tissue engineering. Herein, we present the assembly of lipogels, composite physical hydrogels assembled from poly(vinyl alcohol) and liposomes using thiol-disulfide exchange between end group modified PVA and thiocholesterol containing liposomes, and the response of adhering cells to these coatings. We demonstrate the controlled loading of liposomes into the polymer matrix and the preserved mechanical properties of the lipogels. Furthermore, the lipogels are successfully rendered cell adhesive by incorporation of poly(l-lysine) into the PVA polymer matrix or by poly(dopamine) coating of the lipogels. The successful lipid uptake from the lipogels by macrophages, hepatocytes, and myoblasts was monitored by flow cytometry. Finally, the delivery of active cargo, paclitaxel, to adherent myoblasts is shown, thus illustrating the potential of the lipogels as a drug eluting interface for biomedical applications. Electronic supplementary information (ESI) available: Paclitaxel calibration curve and images of DIC of PLL blended PVA physical hydrogels, lipogel FRAP, and different cell lines attached to lipogels are available. See DOI: 10.1039/c3nr01662e

Jensen, Bettina E. B.; Hosta-Rigau, Leticia; Spycher, Philipp R.; Reimhult, Erik; Städler, Brigitte; Zelikin, Alexander N.

2013-07-01

373

Tetrazole acetic acid: tautomers, conformers, and isomerization.  

PubMed

Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0-8 kJ mol(-1) energy range and should be appreciably populated at the sublimation temperature (?330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol(-1)) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol(-1)). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm(-1), where the first OH stretching overtone vibrations of 1ccc and 2pcc occur. The reverse transformations could be induced by irradiations at 7010 and 7030 cm(-1), transforming 1cct and 2pct back to 1ccc and 2pcc, also selectively. Besides the NIR-induced transformations, the photogenerated 1cct and 2pct forms also decay in N2 matrices back to 1ccc and 2pcc spontaneously, with characteristic decay times of hours (1H) and tens of minutes (2H). The decay mechanism is rationalized in terms of the proton tunneling. In crystals, TAA exists exclusively as 1H-tautomer. By contrast, the tautomeric composition of the matrix-isolated monomers was found to consist of both 1H- and 2H-tautomers, in comparable amounts. A mechanistic discussion of the tautomerization process occurring during sublimation, accounting also for the observed minor decomposition of TAA leading to CO2 and 5-methyl-tetrazole, is proposed. PMID:24527914

Araujo-Andrade, C; Reva, I; Fausto, R

2014-02-14

374

Tetrazole acetic acid: Tautomers, conformers, and isomerization  

NASA Astrophysics Data System (ADS)

Monomers of (tetrazol-5-yl)-acetic acid (TAA) were obtained by sublimation of the crystalline compound and the resulting vapors were isolated in cryogenic nitrogen matrices at 13 K. The conformational and tautomeric composition of TAA in the matrix was characterized by infrared spectroscopy and vibrational calculations carried out at the B3LYP/6-311++G(d,p) level. TAA may adopt two tautomeric modifications, 1H- and 2H-, depending on the position of the annular hydrogen atom. Two-dimensional potential energy surfaces (PESs) of TAA were theoretically calculated at the MP2/6-311++G(d,p) level, for each tautomer. Four and six symmetry-unique minima were located on these PESs, for 1H- and 2H-TAA, respectively. The energetics of the detected minima was subsequently refined by calculations at the QCISD level. Two 1H- and three 2H-conformers fall within the 0-8 kJ mol-1 energy range and should be appreciably populated at the sublimation temperature (˜330 K). Observation of only one conformer for each tautomer (1ccc and 2pcc) is explained in terms of calculated barriers to conformational rearrangements. All conformers with the cis O=COH moiety are separated by low barriers (less than 10 kJ mol-1) and collapse to the most stable 1ccc (1H-) and 2pcc (2H-) forms during deposition of the matrix. On the trans O=COH surfaces, the relative energies are very high (between 12 and 27 kJ mol-1). The trans forms are not thermally populated at the sublimation conditions and were not detected in matrices. One high-energy form in each tautomer, 1cct (1H-) and 2pct (2H-), was found to differ from the most stable form only by rotation of the OH group and separated from other forms by high barriers. This opened a perspective for their stabilization in a matrix. 1cct and 2pct were generated in the matrices selectively by means of narrow-band near-infrared (NIR) irradiations of the samples at 6920 and 6937 cm-1, where the first OH stretching overtone vibrations of 1ccc and 2pcc occur. The reverse transformations could be induced by irradiations at 7010 and 7030 cm-1, transforming 1cct and 2pct back to 1ccc and 2pcc, also selectively. Besides the NIR-induced transformations, the photogenerated 1cct and 2pct forms also decay in N2 matrices back to 1ccc and 2pcc spontaneously, with characteristic decay times of hours (1H) and tens of minutes (2H). The decay mechanism is rationalized in terms of the proton tunneling. In crystals, TAA exists exclusively as 1H-tautomer. By contrast, the tautomeric composition of the matrix-isolated monomers was found to consist of both 1H- and 2H-tautomers, in comparable amounts. A mechanistic discussion of the tautomerization process occurring during sublimation, accounting also for the observed minor decomposition of TAA leading to CO2 and 5-methyl-tetrazole, is proposed.

Araujo-Andrade, C.; Reva, I.; Fausto, R.

2014-02-01

375

Multi-core cable-like TiO2 nanofibrous membranes for dye-sensitized solar cells  

NASA Astrophysics Data System (ADS)

Multi-core cable-like TiO2 nanofibres were fabricated by calcination of composite polyvinyl acetate (PVAc)/titania nanofibres with a hot pressing pre-treatment. This resultant novel fibre structure was composed of sheaths of 200 nm in diameter and 25 nm in wall thickness, and cores filled with 24 nm thick TiO2 fibrils. The formation of multi-core cable-like structures of fibres is considered to be due to the enhanced phase separation of PVAc-rich and TiO2-rich phases during the hot pressing process. The BET results showed that the specific surface area of pressed TiO2 membranes was much higher than that of unpressed TiO2 membranes. In this study, the novel multi-core cable-like TiO2 fibrous membranes were used as electrode materials for dye-sensitized solar cells (DSSCs). It was observed that the photocurrent and conversion efficiency of the electrodes increased concurrently with increasing applied pressure and average membrane thickness in the range of 1-9 µm. The maximum short circuit photocurrent and energy conversion efficiency were 16.09 mA cm-2 and 5.77% when the membrane had an average thickness of 9.21 µm and 8 MPa applied pressure.

Kokubo, Hiroshi; Ding, Bin; Naka, Takayuki; Tsuchihira, Hiroki; Shiratori, Seimei

2007-04-01

376

Atomic and electronic structure of acetic acid on Ge(100) Do Hwan Kim a,b  

E-print Network

Atomic and electronic structure of acetic acid on Ge(100) Do Hwan Kim a,b , Eunkyung Hwang to investigate the atomic and electronic structure of acetic acid adsorbed on Ge(100) surface. Due to its acidity, acetic acid dissociates and the resulting electron-rich acetate group reacts with the electron

Kim, Sehun

377

values from the non-steady state equation to the steady state at plateaus. The acetate  

E-print Network

values from the non-steady state equation to the steady state at plateaus. The acetate endogenous fluxes did not change during cold acetate infusions of 7 and 14 Ilmol.kg-I.min-I (6 ± 2 et 5 ± 2 pmol the total flux of acetate was higher than 21 1 pmol,kg!',min!' .!. We concluded that the acetate fluxes cal

Boyer, Edmond

378

A Study of Specific Heat Capacity Functions of Polyvinyl Alcohol- Cassava Starch Blends  

NASA Astrophysics Data System (ADS)

The specific heat capacity ( C sp) of polyvinyl alcohol (PVOH) blends with cassava starch (CSS) was studied by the differential scanning calorimetry method. Specimens of PVOH-CSS blends: PPV37 (70 mass% CSS) and PPV46 (60 mass% CSS) were prepared by a melt blending method with glycerol added as a plasticizer. The results showed that the specific heat capacity of PPV37 and PPV46 at temperatures from 330 K to 530 K increased from (2.963 to 14.995) J· g-1 · K-1 and (2.517 to 14.727) J · g-1· K-1, respectively. The specific heat capacity of PVOH-CSS depends on the amount of starch. The specific heat capacity of the specimens can be approximated by polynomial equations with a curve fitting regression > 0.992. For instance, the specific heat capacity (in J · g-1 · K-1) of PPV37 can be expressed by C sp = -17.824 + 0.063 T and PPV46 by C sp = -18.047 + 0.061 T, where T is the temperature (in K).

Sin, Lee Tin; Rahman, W. A. W. A.; Rahmat, A. R.; Morad, N. A.; Salleh, M. S. N.

2010-03-01

379

Fabrication of reactive poly(vinyl alcohol) membranes for prevention of bone cement leakage.  

PubMed

Leakage of bone cement into the spinal canal has been reported to cause many adverse effects. In this study, we designed an implantable balloon kyphoplasty material that avoids cement leakage through the formation of covalent bonds with the bone cement. For this purpose, glycidyl methacrylate (GMA) was used as a reactive functional group attached to the poly(vinyl alcohol) (PVA) membrane. The prepared membrane adhered to poly(methyl methacrylate) (PMMA)-based bone cements within 10 min, which is the time required for PMMA polymerization in the bone cement. The bonding strength between the GMA-PVA membrane and the PMMA-based bone cement was higher than that for the original PVA membrane, likely because vinyl bonds form between the surface of the GMA-PVA membrane and the bone cement. Since the GMA-PVA membrane adhered firmly to the PMMA-based bone cement, the membrane was able to completely cover the PMMA-based bone cement. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 102B: 1786-1791, 2014. PMID:24700680

Inoue, Motoki; Sakane, Masataka; Taguchi, Tetsushi

2014-11-01

380

Synthesis of poly(vinyl alcohol)-magnetite ferrogel obtained by freezing-thawing technique  

NASA Astrophysics Data System (ADS)

Polymer gels are crosslinked polymer networks swollen by a fluid. If magnetic particles either as powder or dispersed in a magnetic fluid are introduced into the gel then the system becomes sensitive to external magnetic fields and the resulting material is called ferrogel. The polyvinyl alcohol (PVA)-magnetite ferrogels system has properties that are attractive for artificial muscles and drug delivery systems for biomedical applications. This work investigates the synthesis and characterization of a ferrogel obtained by freezing-thawing cycles. PVA ( MW=89,000-98,000, degree of hydrolyzation: 99 mol%) and magnetite nanoparticles (˜12 nm) obtained by chemical coprecipitation were used as raw materials. The PVA-magnetite ferrogels were prepared by subjecting a PVA/DMSO/magnetite solution (2 g/30 ml/0.2 g) to freeze (-25 °C)/thaw (+25 °C) cycles. The resulting ferrogel was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and vibration sample magnetometry (VSM). The magnetic particles inside the PVA matrix formed agglomerates with average size ˜58 nm. All the ferrogels showed superparamagnetic behavior with maximum magnetization of 0.6 emu/g.

Reséndiz-Hernández, P. J.; Rodríguez-Fernández, O. S.; García-Cerda, L. A.

381

Poly(vinyl chloride) ion-selective electrodes for piribedil determination.  

PubMed

Piribedil (PD) ion-selective electrodes have been constructed from poly(vinyl chloride) matrix membrane containing piribedil-tetraphenylborate (PD-TPB) as the electroactive component with dibutylphthalate or dioctylphthalate as the plasticizing solvent mediator. The electrodes displayed a linear response over the concentration range 2.0 x 10(-5) to 10(-2) M PD. The working pH ranges of the electrodes were 3.5-6.4 and 3.0-6.0, and the isothermal coefficients of the cells were 0.00129 and 0.00096 V/degrees C respectively. The electrodes were used for the determination of the diprotonated PD species, the most successful being that based on dioctylphthalate solvent mediator. The electrodes show a linear response over the concentration range of 8.0 x 10(-6) to 10(-2) M PD, with Nernstain slope 30 mV/PD concentration decade when preconditioned by soaking in distilled water for 30 min. The electrodes exhibit good selectivity for the PD with respect to a large number of inorganic cations and organic substances of biological fluids. Piribedil is determined successfully in pure solutions and in tablets or in biological fluids using the standard additions and potentiometric titration methods. The membrane withstood soaking in distilled water for more than 5 months. PMID:10933543

Issa, Y M; Hassouna, M M; Abdel-Gawad, F M; Hussien, E M

2000-08-15

382

In-line ultrasonic monitoring for sediments stuck on inner wall of a polyvinyl chloride pipe.  

PubMed

This research verified the applicability and effectiveness of the ultrasonic monitoring of sediments stuck on the inner wall of polyvinyl chloride (PVC) pipes. For identifying the transmittance of acoustic energy and the speed of sound in the PVC material, the pulse-echo ultrasonic testing was conducted for PVC sheets of different thicknesses. To simulate the solidified sediment, the hot melt adhesive (HMA) was covered on the inner wall of the PVC pipe in different heights. From the experiment, the speeds of sound in the PVC and the HMA materials were obtained as about 2258 and 2000 m/s, respectively. The thickness of the materials was calculated through the signal processing such as taking the absolute value and low pass filtering, the echo detection, and the measurement of the time of flight. The errors between actual and measured thicknesses of PVC sheets were below 5%. In the case of the substance stuck on the inner wall, the errors were below 2.5%. Since the pulse-echo ultrasonic inspection is available on the outer surface and its measurement accuracy was over 95%, it can be an efficient and effective in-service structural health monitoring for the sediment on the wall of PVC pipes. PMID:25243223

Seo, Hogeon; Lee, Kyoungjun; Jhang, Kyung-Young

2014-01-01

383

Multiwall carbon nanotube polyvinyl alcohol-based saturable absorber in passively Q-switched fiber laser.  

PubMed

In this work, we demonstrated a compact Q-switched erbium-doped fiber laser capable of generating high-energy pulses using a newly developed multiwall carbon nanotube (CNT) polyvinyl alcohol (PVA) thin film based saturable absorber. Q-switched pulse operation is obtained by sandwiching the thin film between two fiber ferrules forming a saturable absorber. A saturable absorber with 1.25 wt. % of PVA concentration shows a consistency in generating pulsed laser with a good range of tunable repetition rate, shortest pulse width, and produces a high pulse energy and peak power. The pulse train generated has a maximum repetition rate of 29.9 kHz with a corresponding pulse width of 3.49 ?s as a function of maximum pump power of 32.15 mW. The maximum average output power of the Q-switched fiber laser system is 1.49 mW, which translates to a pulse energy of 49.8 nJ. The proposed method of multiwall CNT/PVA thin film fabrication is low in cost and involves uncomplicated processes. PMID:25402790

Ahmad, H; Ismail, M F; Hassan, S N M; Ahmad, F; Zulkifli, M Z; Harun, S W

2014-10-20

384

Improved ion-selective detection method using nanopipette with poly(vinyl chloride)-based membrane.  

PubMed

Ion-selective electrodes (ISEs) are widely used to detect targeted ions in solution selectively. Application of an ISE to a small area detection system with a nanopipette requires a special measurement method in order to avoid the enhanced background signal problem caused by a cation-rich layer near the charged inner surface of the nanopipette and the selectivity change problem due to relatively fast saturation of the ISE inside the nanopipette. We developed a novel ion-selective detection system using a nanopipette that measures an alternating current (AC) signal mediated by saturated ionophores in a poly(vinyl chloride) (PVC) membrane located at the conical shank of the nanopipette to solve the above problems. Small but reliable K(+) and Na(+) ionic current passing through a PVC membrane containing saturated bis(benzo-15-crown-5) and bis(12-crown-4) ionophore, respectively, could be selectively detected using the AC signal measurement system equipped with a lock-in amplifier. PMID:24766420

Kang, Eun Ji; Takami, Tomohide; Deng, Xiao Long; Son, Jong Wan; Kawai, Tomoji; Park, Bae Ho

2014-05-15

385

Dye Adsorption Behavior of Polyvinyl Alcohol/Glutaraldehyde/?-Cyclodextrin Polymer Membranes  

NASA Astrophysics Data System (ADS)

Crosslinked polyvinyl alcohol/glutaraldehyde (PVA/GA) membranes were prepared, and attempts to obtain hydrophilic crosslinked PVA membranes were made by adding various amounts of ?-cyclodexrin (?-CD), which is a typical cyclic oligosaccharide able to form inclusion complexes with organic host molecules (host-guest complexes). Thus, membranes of PVA/GA/?-CD were synthesized. The membranes were characterized by infrared spectroscopy (FTIR) and swelling measurements. The ability of cyclodextrin to include a wide variety of chemicals was also exploited for the dye adsorption to show the potentialities of the membranes in textile liquid waste processing. Adsorption of reactive methyl orange, and methylene blue dyes on PVA/GA/?-CD membranes was consequently studied using UV-Vis spectroscopy at wavelengths of 547, 463, and 660 nm. Adsorption reached equilibrium after 24 h. Results indicated that there is no covalent bond formation between PVA and ?-CD; the ?-CD is completely mixed into the PVA matrix polymer. The adsorption capacity increases with increasing amounts of cyclodextrin; the maximum adsorption capacity was obtained with 8% ?-CD. Therefore, the change in adsorption capacities may be due to the dye structure effect, and the negative value of free energy indicated the spontaneous nature of adsorption.

Ghemati, Dj.; Aliouche, Dj.

2014-05-01

386

Kinetic evaluation study on the bioactivity of silver doped hydroxyapatite-polyvinyl alcohol nanocomposites.  

PubMed

This work investigates the effect of adding silver nanoparticles (NPs) in ppm on the bioactivity of hydroxyapatite/polyvinyl alcohol nanocomposites (HAV). HAV prepared by an in situ biomimetic approach was doped with different concentrations of silver NPs (HAV-Ag), and the formed powder samples were characterized by different techniques such as Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-EOS), X-ray diffraction, transmission electron microscope, and Fourier Transform Infrared Spectroscopy. Bioactivity was evaluated in simulated body fluid through studying the kinetics of Ca and P uptake onto the different HAV-Ag nanocomposites. Uptake profiles of Ca and P were well described by a pseudo-second order kinetic model, and the obtained kinetic parameters confirmed that the highest uptake capacities were achieved by adding less than 0.001 ppm of silver NPs which is an amount not detectable by ICP. Furthermore, HAV-Ag nanocomposites were shown to be non-toxic as well as have a strong antibacterial effect. Silver NPs significantly enhanced the bioactivity of HAV nanocomposites and thus the developed nanocomposites promise to be excellent biomaterials for bone and reconstructive surgery applications. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 4609-4615, 2014. PMID:24610881

Mostafa, Amany A; Oudadesse, Hassane; El Sayed, Mayyada M H; Kamal, Gehan; Kamel, Mohamed; Foad, Enas

2014-12-01

387

Radiation sensitive indicator based on tetrabromophenol blue dyed poly(vinyl alcohol)  

NASA Astrophysics Data System (ADS)

Radiation sensitive indicators based on dyed polyvinyl alcohol (PVA) containing acid- sensitive dye (tetrabromophenol blue, TBPB) and chloral hydrate (CCl3·CH·(OH)2, 2,2,2-trichloroethane-1,1-diol) have been developed. These plastic film dosimeters undergo color change from blue (the alkaline form of TBPB) to yellow (the acidic form of TBPB), indicating acid formation. The concentration of radiation formed acids in the films containing different concentrations of chloral hydrate was calculated at different doses. These films can be used as dosimeters for food irradiation applications where the maximum of the useful dose ranges are between 1 and 8 kGy depending on chloral hydrate concentration in the film. The films have the advantage of negligible humidity effects on response in the intermediate range of relative humidity from 0 to 70% as good post irradiation stability when stored in the dark at room temperature. The overall combined uncertainty (at 2?) associated with measurement of response (?A mm-1) at 623 nm for dose range 1-8 kGy is 4.53%.

Beshir, W. B.

2013-05-01

388

Development of polyvinyl alcohol shells overcoated with polystyrene layer for inertial confinement fusion experiments  

SciTech Connect

In inertial fusion experiments, the use of polymer shells provides more efficient ablative implosion and significantly reduced radiation preheat compared with the glass shells currently used. We have developed a method of fabricating polyvinyl alcohol (PVA) shells overcoated with a polystyrene (PS) layer. The method utilizes the emulsion technique previously developed by us, and employs three different liquid phases. A 5 wt. % aqueous PVA solution is mixed with a 7 wt. % PS solution in dichloromethane while stirring. The mixture is then poured into a 1 wt. % PS solution in cidhloromethane while stirring. The mixture is then poured into a 1 wt. % aqueous gelatin solution. The resulting emulsion is heated to evaporate the dichloromethane, resulting in solid PS shells encapsulating the PVA solution. The PS shells are subsequently washed and dried in vacuum to drive off the remaining water. As a result, a PVA shell is formed inside an overcoating PS shell which exhibits a good surface quality in the outer diameter and wall thickness regime currently desired by inertial confinement fusion experimenters.

Kubo, U.; Tsubakihara, H.

1987-07-01

389

Vinyl monomers-induced synthesis of polyvinyl alcohol-stabilized selenium nanoparticles  

SciTech Connect

A simple wet chemical method has been developed to synthesize selenium nanoparticles (size 100-200 nm), by reaction of sodium selenosulphate precursor with different vinyl monomers, such as acrylamide, N,N'-dimethylene bis acrylamide, methyl methacrylate, sodium acrylate, etc., in aqueous medium, under ambient conditions. Polyvinyl alcohol has been used to stabilize the selenium nanoparticles. Average size of the synthesized selenium nanoparticles can be controlled by adjusting concentration of both the precursors and the stabilizer. Rate of the reaction as well as size of the resultant selenium nanoparticles have been correlated with the functional groups of the different monomers. UV-vis optical absorption spectroscopy, X-ray diffraction, energy dispersive X-rays, differential scanning calorimetry, atomic force microscopy, scanning electron microscopy and transmission electron microscopy techniques have been employed to characterize the synthesized selenium nanoparticles. Gas chromatographic analysis of the reaction mixture established the non-catalytic role of the vinyl monomers, which were found to be consumed during the course of the reaction.

Shah, Chetan P.; Singh, Krishan K. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)] [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Kumar, Manmohan, E-mail: manmoku@barc.gov.in [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)] [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India); Bajaj, Parma N. [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)] [Radiation and Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085 (India)

2010-01-15

390

Thalassospira povalilytica sp. nov., a polyvinyl-alcohol-degrading marine bacterium.  

PubMed

A polyvinyl-alcohol-degrading marine bacterium was isolated from plastic rope litter found in Tokyo Bay, Japan. The isolated strain, Zumi 95(T), was a Gram-reaction-negative, non-spore-forming and facultatively anaerobic chemo-organotroph. The major respiratory quinone was Q-10. The predominant fatty acids were C18?:?1?7c and C16?:?0. On the basis of 16S rRNA gene sequence analysis, the isolated strain was closely affiliated with members of the genus Thalassospira in the class Alphaproteobacteria. The DNA G+C content of the novel strain was 55.1 mol%. The hybridization values for DNA-DNA relatedness between this strain and four reference strains representing species of the genus Thalassospira were significantly lower than that accepted as the phylogenetic definition of a species. On the basis of differences in taxonomic characteristics, the isolated strain represents a novel species of the genus Thalassospira for which the name Thalassospira povalilytica sp. nov. (type strain Zumi 95(T)?=?JCM 18746(T)?=?DSM 26719(T)) is proposed. PMID:24408523

Nogi, Yuichi; Yoshizumi, Masaki; Miyazaki, Masayuki

2014-04-01

391

Isolation and molecular characterization of polyvinyl chloride (PVC) plastic degrading fungal isolates.  

PubMed

The recalcitrant nature of polyvinyl chloride creates serious environmental concerns during manufacturing and waste disposal. The present study was aimed to isolate and screen different soil fungi having potential to biodegrade PVC films. After 10 months of soil burial experiment, it was observed that a number of fungal strains were flourishing on PVC films. On morphological as well as on 18rRNA gene sequence and phylogenetic basis they were identified as Phanerochaete chrysosporium PV1, Lentinus tigrinus PV2, Aspergillus niger PV3, and Aspergillus sydowii PV4. The biodegradation ability of these fungal isolates was further checked in shake flask experiments by taking thin films of PVC (C source) in mineral salt medium. A significant change in color and surface deterioration of PVC films was confirmed through visual observation and Scanning electron microscopy. During shake flask experiments, P. chrysosporium PV1 produced maximum biomass of about 2.57?mg?ml(-1) followed by A. niger PV3. P. chrysosporium PV1 showed significant reduction (178,292?Da(-1)) in Molecular weight of the PVC film than control (200,000?Da(-1)) by gel permeation chromatography. Furthermore more Fourier transform infrared spectroscopy and nuclear magnetic resonance also revealed structural changes in the PVC. It was concluded that isolated fungal strains have significant potential for biodegradation of PVC plastics. PMID:23686796

Ali, Muhammad Ishtiaq; Ahmed, Safia; Robson, Geoff; Javed, Imran; Ali, Naeem; Atiq, Naima; Hameed, Abdul

2014-01-01

392

Furanone-containing poly(vinyl alcohol) nanofibers for cell-adhesion inhibition.  

PubMed

The 3(2H) furanone derivative 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) was investigated for its antimicrobial and cell-adhesion inhibition properties against Klebsiella pneumoniae Xen 39, Staphylococcus aureus Xen 36, Escherichia coli Xen 14, Pseudomonas aeruginosa Xen 5 and Salmonella typhimurium Xen 26. Nanofibers electrospun from solution blends of DMHF and poly(vinyl alcohol) (PVA) were tested for their ability to inhibit surface-attachment of bacteria. Antimicrobial and adhesion inhibition activity was determined via the plate counting technique. To quantify viable but non-culturable cells and to validate the plate counting results, bioluminescence and fluorescence studies were carried out. Nanofiber production was upscaled using the bubble electrospinning technique. To ascertain that no DMHF leached into filtered water, samples of water filtered through the nanofibrous mats were analyzed using gas chromatography coupled with mass spectrometry (GC-MS). Scanning electron microscopy (SEM) and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) were used to characterize the electrospun nanofibers. PMID:23261340

Gule, Nonjabulo P; de Kwaadsteniet, Michele; Cloete, Thomas E; Klumperman, Bert

2013-03-01

393

Shock pressure measurements in Polyvinyl alcohol (PVA) films using multi-frame optical shadowgraphy  

NASA Astrophysics Data System (ADS)

The knowledge of the equation of state (EOS) of materials at high pressures in excess of 10 Mbar is important in several branches of physics including astrophysics and inertial confinement fusion. It is possible to access this high pressure regime in the laboratory using shock waves launched by the interaction of a high power laser with a solid target. To study laser driven shock waves in plastic (Polyvinyl alcohol) (C2H4O)n targets, a multiframe optical shadowgraphy technique has been developed, with spatial and temporal resolution of 12 ?m and 500 ps respectively. The experiments were performed using the 1064 nm 20 J /500 ps Nd: Glass laser at BARC. The focused laser intensity on target was varied between 6 × 1013 W/cm2 and 2.7 × 1014 W/cm2. The experimental data have been compared with the results of previous experimental and theoretical studies. The results are also found to be in agreement with SESAME data. The maximum pressure attained in the experiments was 30 Mbar, achieved with a laser intensity of 2.7 × 1014 W/cm2.

Chaurasia, S.; Tripathi, S.; Leshma, P.; Pasley, J.; Kumar, M.

2012-07-01

394

Estimated risks of water and saliva contamination by phthalate diffusion from plasticized polyvinyl chloride.  

PubMed

Phthalates are additives commonly used to convert hard polyvinyl chloride (PVC) resins into flexible and workable plastics employed in the production of chewable rubber toys and other soft-plastic products. In theory, phthalates can diffuse in small quantities to the surface of a product, and from there they can enter the environment and the human body. The purpose of this study was to determine the diffusion of phthalates from plasticized PVC in water and artificial saliva; to determine the migration of di(2-ethylhexyl) (DEHP) phthalate in human saliva using gas chromatography; to compare the experimental values with theoretical values calculated using a model based on the principles of molecular diffusion in fluids; and to use the experimental values to estimate daily doses of DEHP received by Mexican children and infants using plastic and soft-plastic products (e.g., pacifiers, chewable toys, and bottles). Our findings indicated phthalate diffusion of 0.36 microg/cm2 per hour and 4.10 microg/cm2 per hour, respectively, in water and artificial saliva. The average value of phthalate diffusion in vivo was 6.04 microg/cm2 per hour. The daily oral phthalate exposure in Mexican infants and toddlers from oral use of rubber toys and soft-plastic products is 18.12 microg/kg. These daily doses are considerably lower than the maximum daily phthalate intake recommended by an international public health committee. PMID:18990931

Corea-Téllez, Kira S; Bustamante-Montes, Patricia; García-Fábila, Magdalena; Hernández-Valero, María A; Vázquez-Moreno, Flavio

2008-10-01

395

Glucose oxidase encapsulated polyvinyl alcohol-silica hybrid films for an electrochemical glucose sensing electrode.  

PubMed

An amperometric glucose enzyme electrode was developed by the immobilization of glucose oxidase (GOD) in a composite material based on polyvinyl alcohol (PVA) and partially prehydrolyzed tetraethyl orthosilicate (pphTEOS) on the surface of "in-house" fabricated graphite electrodes. For comparison, silver and gold nanoparticles (Ag/AuNPs) embedded in the PVA-pphTEOS matrix was prepared through a novel method via sol-gel process based on the in situ chemical reduction of Ag or Au ions using PVA as a reducing agent and stabilizer. The successful incorporation of Ag and AuNPs ranging from 5 to 7.5 and 4.5-11 nm, respectively, in the PVA-pphTEOS matrix was confirmed by UV-Vis spectroscopy, TEM, and EDX analysis. The PVA-TEOS matrix was also characterized by FTIR spectroscopy. The analytical performance of the enzyme electrodes were studied in terms of linear ranges, sensitivities, response times, limits of detection, reproducibility and stability. PMID:23742133

Lad, Umesh; Kale, Girish M; Bryaskova, Rayna

2013-07-01

396

Plasma functionalization of poly(vinyl alcohol) hydrogel for cell adhesion enhancement  

PubMed Central

Tailoring the interface interactions between a biomaterial and the surrounding tissue is a capital aspect to consider for the design of medical devices. Poly(vinyl alcohol) (PVA) hydrogels present suitable mechanical properties for various biological substitutes, however the lack of cell adhesion on their surface is often a problem. The common approach is to incorporate biomolecules, either by blending or coupling. But these modifications disrupt PVA intra- and intermolecular interactions leading therefore to a loss of its original mechanical properties. In this work, surface modification by glow discharge plasma, technique known to modify only the surface without altering the bulk properties, has been investigated to promote cell attachment on PVA substrates. N2/H2 microwave plasma treatment has been performed, and the chemical composition of PVA surface has been investigated. X-ray photoelectron and Fourier transform infrared analyses on the plasma-treated films revealed the presence of carbonyl and nitrogen species, including amine and amide groups, while the main structure of PVA was unchanged. Plasma modification induced an increase in the PVA surface wettability with no significant change in surface roughness. In contrast to untreated PVA, plasma-modified films allowed successful culture of mouse fibroblasts and human endothelial cells. These results evidenced that the grafting was stable after rehydration and that it displayed cell adhesive properties. Thus plasma amination of PVA is a promising approach to improve cell behavior on contact with synthetic hydrogels for tissue engineering. PMID:23989063

Ino, Julia M.; Chevallier, Pascale; Letourneur, Didier; Mantovani, Diego; Le Visage, Catherine

2013-01-01

397

Characterization, charge transport and magnetic properties of multi-walled carbon nanotube-polyvinyl chloride nanocomposites  

NASA Astrophysics Data System (ADS)

Multi-walled carbon nanotube (MWCNT)-polyvinyl chloride (PVC) nanocomposites, with MWCNT loading up to 44.4 weight percent (wt%), were prepared by the solvent mixing and casting method. Electron microscopy indicates high degree of dispersion of MWCNT in PVC matrix, achieved by ultrasonication without using any surfactants. Thermogravimetric analysis showed a significant monotonic enhancement in the thermal stability of nanocomposites by increasing the wt% of MWCNT. Electrical conductivity of nanocomposites followed the classical percolation theory and the conductivity prominently improved from 10-7 to 9 S/cm as the MWCNT loading increased from 0.1 to 44.4 wt%. Low value of electrical percolation threshold ~0.2 wt% is achieved which is attributed to high aspect ratio and homogeneous dispersion of MWCNT in PVC. The analysis of the low temperature electrical resistivity data shows that sample of 1.9 wt% follows three dimensional variable range hopping model whereas higher wt% nanocomposite samples follow power law behavior. The magnetization versus applied field data for both bulk MWCNTs and nanocomposite of 44.4 wt% display ferromagnetic behavior with enhanced coercivities of 1.82 and 1.27 kOe at 10 K, respectively. The enhancement in coercivity is due to strong dipolar interaction and shape anisotropy of rod-shaped iron nanoparticles.

M. S., Vasanthkumar; Bhatia, Ravi; Arya, Ved Prakash; Sameera, I.; Prasad, V.; H. S., Jayanna

2014-02-01

398

Determination of lead oxide and sulfate content in polyvinyl chloride used for cable insulation  

SciTech Connect

The purpose of this paper is to develop a rapid and reproducible procedure for determining lead as the key component of polyvinyl chloride (PVC) stabilizers, used for cable insulation. To develop this method, the authors paid attention also to the effect of the other inorganic ions present in the insulation. Lead ions can be determined complexometrically using xylenol orange as an indicator. The authors efforts to determine lead in the inorganic residue of cable insulation by direct titration with EDTA solution did not yield satisfactory results due to the difficulty in pinpointing the moment of color change at the end of the titration, so the authors employed back titration, binding lead(II) into a stable complex of lead by treating the mixture with an excess of EDTA under heating, and determining this excess by titration with a standard solution of lead (nitrogen trioxide). Since complexometric determination is carried out in an acidic medium, Al(III), Fe(III), and Cu(II) are titrated together with lead ions. The authors recommend this method for separate determinations of lead oxide and sulfate determination in PVC used for cable insulation.

Popova, E.M.; Dimitrova, V.T.; Tsonkova, S.D.; Kulev, I.I.

1987-03-01

399

Electrospinning of porphyrin/polyvinyl alcohol (PVA) nanofibers and their acid vapor sensing capability.  

PubMed

Fluorescing 5,10,15,20-terakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP)-embedded and -coated polyvinyl alcohol (PVA) nanofibers were fabricated by using the electrospinning technique. To improve nonpolar solvent solubility of TMPyP/PVA nanofibers, tetraethyl orthosilicate (TEOS) was used as a cross-linking agent. UV-vis spectroscopy showed a strong Q band and two relatively weak Soret bands from the TMPyP/PVA nanofibers, and revealed that the TMPyP molecules were homogeneously loaded to the fibers. Scanning electron microscopy revealed that the electrospun nanofibers had ultrafine structures with an average diameter of ca. 250 nm. X-ray photoelectron spectroscopy confirmed the compositional structure of TMPyP/PVA/TEOS nanofibers and revealed the relative coverage of TMPyP molecules on the surface of TMPyP-embedded and TMPyP-coated PVA/TEOS fibers. For the comparison of the acid vapor sensitivity, TMPyP-embedded PVA/TEOS films, and TMPyP-embedded PVA/TEOS fibers, TMPyP-coated PVA/TEOS fibers were exposed to 1N nitric-acid vapor for 20-60 seconds. Fluorescence microscopy revealed that TMPyP-coated PVA/TEOS nanofibers exhibited better acid-sensing capability than TMPyP-embedded PVA/TEOS nanofibers and films. PMID:22121666

Jang, Kihun; Baek, Il Woong; Back, Sung Yul; Ahn, Heejoon

2011-07-01

400

Formation and fluidity measurement of supported lipid bilayer on polyvinyl chloride membrane  

NASA Astrophysics Data System (ADS)

We prepared an artificial lipid bilayer on a plasticized poly(vinyl chloride) (PVC) membrane on a Si3N4 layer deposited on a Si wafer. We optimized the experimental condition for the fabrication of the PVC membrane, and obtained a PVC membrane with a flat and uniform surface on the scale of several hundreds of micrometer suitable for a substrate for supported lipid bilayers (SLBs). The SLB of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was formed on the PVC membrane by the vesicle fusion method. The observation with a conventional epi-fluorescence microscope and a confocal laser scanning microscope gave geometrically uniform images of the SLB on the PVC membrane. The fluidity and the mobile fraction of the SLB was evaluated by the fluorescence recovery after photobleaching method, and compared with that on a thermally oxidized SiO2/Si substrate. The SLB on the PVC membrane contained immobile fraction ˜30%, but the diffusion in the mobile fraction was two times faster than that in the SLB on SiO2/Si, which had little immobile fraction.

Kobayashi, Takuji; Kono, Akiteru; Futagawa, Masato; Sawada, Kazuaki; Tero, Ryugo

2014-02-01

401

Characterization of poly(vinyl chloride) aged in a bromine containing electrolyte  

SciTech Connect

Poly(vinyl chloride) (PVC) is being considered for use as a flow frame material in a developmental zinc/bromine battery. The choice of PVC was based on its low cost and the ease with which it can be molded into complex parts. The electrolyte used in this battery is a highly corrosive mixture of bromine, zinc bromide, zinc chloride, potassium bromide, potassium chloride and a quaternary amine salt. The quaternary salt serves to reduce the concentration of free bromine in the electrolyte by virtue of its complexing capability. It is well known that aqueous bromine is capable of oxidizing organic compounds. The purpose of the current study was to investigate the effect of a bromine electrolyte on two PVC formulations, PVC-1 and PVC-4. PVC-1 is the designation given to one of B.F. Goodrich's commercial formulations and is the present baseline material for the flow frame. PVC-4 is an experimental B.F. Goodrich formulation that was developed especially for battery applications. We sought answers to such questions as (1) does oxidation and/or bromination take place. (2) does bromine penetrate into the sample and, if so, how far. (3) how are the mechanical and morphological properties affected. and (4) are there differences in stability between PVC-1 and PVC-4. To accelerate the aging processes we aged the PVC samples at an elevated temperature in an electrolyte which did not contain any complexing agent. 5 refs., 6 figs.

Arnold, C. Jr.; Leo, A.; Tarjani, M.

1988-01-01

402

Effect of gamma irradiation on biopolymer composite films of poly(vinyl alcohol) and bacterial cellulose  

NASA Astrophysics Data System (ADS)

Composite materials containing in different ratios poly(vinyl alcohol) (PVA), bacterial cellulose (BC) and glycerol (G) as plasticizer were obtained and exposed to different ? radiation doses using an irradiator GAMMATOR provided with 137Cs source. These films successively received up to 50 kGy absorbed doses at a dose rate of 0.4 kGy/h at room temperature. In order to study the chemical and structural changes during ? irradiation, Fourier-transformed infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and UV-Vis spectroscopy were used. Water vapour permeability (WVP), Hunter colour parameters and hardness were also measured for the irradiated samples. Investigation revealed that WVP was not significantly affected by the irradiation. Colour measurements indicated a slight decrease of pure PVA films transparency and it made clear that all samples became more reddish and yellowish after irradiation. The samples hardness was not affected by the irradiation doses used. However, the results showed no drastic structural or chemical changes of the irradiated samples, which prove, in consequence, a good durability. These composite materials could be used as packaging materials for ? irradiated products.

Jipa, Iuliana Mihaela; Stroescu, Marta; Stoica-Guzun, Anicuta; Dobre, Tanase; Jinga, Sorin; Zaharescu, Traian

2012-05-01

403

Effect of gamma irradiation on the thermal, mechanical and structural properties of chlorinated polyvinyl chloride  

NASA Astrophysics Data System (ADS)

Non isothermal studies were carried out using thermogravimetry (TG) and differential thermogravimetry (DTG) to obtain the activation energy of decomposition for chlorinated polyvinyl chloride (CPVC) before and after exposure to gamma doses at levels between 5.0 and 50.0 KGy. Thermal gravitational analysis (TGA) indicated that the CPVC polymer decomposes in one main breakdown stage and a decrease in activation energies was observed followed by an increase on increasing the gamma dose. The variation of melting temperatures with the gamma dose has been determined using differential thermal analysis (DTA). Also, mechanical and structural property studies were performed on all irradiated and non-irradiated CPVC samples using stress-strain relations and X-ray diffraction. The results indicated that the exposure to gamma doses at levels between 27.5 and 50 KGy leads to further enhancement of the thermal stability, tensile strength and isotropic character of the polymer samples due to the crosslinking phenomenon. This suggests that gamma radiation could be a suitable technique for producing a plastic material with enhanced properties that can be suitable for high temperature applications and might be a suitable candidate for dosimetric applications.

Nouh, S. A.

404

DSC, TGA and dielectric properties of carboxymethyl cellulose/polyvinyl alcohol blends  

NASA Astrophysics Data System (ADS)

Films with different compositions of polyvinyl alcohol (PVA) and carboxymethyl cellulose (CMC) blends have been prepared using the casting method. Differential scanning calorimetery (DSC), thermogravimetric analysis (TGA) and dielectric spectroscopy of all compositions have been investigated. It was found that PVA and CMC are compatible in the studied range of composition. With increasing CMC content, the thermal stability of PVA increases. Based on DSC and TGA data, the activation energies of all the investigated samples were calculated. The absorption edge ( Ea) was also determined from Ultraviolet-visible (UV-vis) spectra. Dielectric permittivity, loss tangent and ac conductivity of all samples were studied as functions of temperature and frequency. The results show that the dielectric dispersion consists of both dipolar and interfacial polarization. The frequency dependence of the ac conductivity indicates that the correlated barrier hopping (CBH) is the most suitable mechanism for conduction. The polaron binding energy ( UM) was determined. Results of the present system are compared with those of similar materials.

El-Sayed, S.; Mahmoud, K. H.; Fatah, A. A.; Hassen, A.

2011-11-01

405

Dehydration of dioxane by pervaporation using filled blend membranes of polyvinyl alcohol and sodium alginate.  

PubMed

Pervaporation membranes were made by solution blending of polyvinyl alcohol (PVA) and sodium alginate (SA). Accordingly, five different blends with PVA:SA weight ratio of 75:25, 50:50, 25:75, 20:80 and 10:90 designated as PS1, PS2, PS3, PS4 and PS5, respectively, were prepared. Each of these blends was crosslinked with 2, 4 and 6 wt% glutaraldehyde and the resulting fifteen (5 × 3) membranes were used for pervaporative separation of 90 wt% dioxane in water. The membranes made from PS4 and PS5 were not stable during pervaporation experiments. Among the stable membranes PS3 membrane crosslinked with 2 wt% glutaraldehyde showed the best results for flux and selectivity. Thus, it was filled with nano size sodium montmorillonite filler and used for separation of dioxane-water mixtures over the entire concentration range of 80-99.5 wt% dioxane in water. The membranes were also characterized by mechanical properties, FTIR, SEM, DTA-TGA and XRD. PMID:24299887

Kuila, Sunil Baran; Ray, Samit Kumar

2014-01-30

406

Immobilized laccase on activated poly(vinyl alcohol) microspheres for enzyme thermistor application.  

PubMed

Poly(vinyl alcohol) (PVA) microspheres were prepared by inverse suspension crosslinked method, with glutaraldehyde as a crosslinking agent. PVA microspheres activated with aldehyde groups were employed for Trametes versicolor laccase immobilization. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the activated PVA microspheres and PVA microspheres with immobilized laccase (Lac/PVA microspheres), which show that laccase was successfully immobilized on the PVA microspheres. The optimum pH and temperature coupling conditions for the immobilized laccase were determined to be 3.3 and 30 °C, respectively. Residual activity was also investigated by soaking the immobilized laccase in organic solvents at different concentrations, proving it chemically stable. Immobilized laccase exhibited good storage stability at 4 °C. The enzyme biosensor showed good performance in 2,2-azinobis(3-ethylthiazoline-6-sulfonate) and bisphenol A, with concentration ranges of 2 to 8 mM and 0.05 to 0.25 mM, respectively. Therefore, PVA microspheres may have high potential as support for enzyme thermistor applications. PMID:24760609

Bai, Xue; Gu, Haixin; Chen, Wei; Shi, Hanchang; Yang, Bei; Huang, Xin; Zhang, Qi

2014-07-01

407

Tortuously structured polyvinyl chloride/polyurethane fibrous membranes for high-efficiency fine particulate filtration.  

PubMed

Two-tier composite filtration medium exhibiting excellent filtration performance to airborne particulate was prepared by a facile deposition of electrospun polyvinyl chloride (PVC)/polyurethane (PU) fibers on a conventional filter paper support. The tortuous structure and composition of resultant fibrous membranes can be finely controlled by regulating the precursor solution composition. By employing the PU incorporation, the pristine PVC fibrous membranes were endowed with robust tensile strength approaching to 9.9 MPa. The plausible correlation between resultant blended fibrous structure and mechanical property of relevant membranes was discussed, and a three-step break mechanism upon the external stress was proposed. Additionally, quantitative pore size and porosity distribution analysis using the capillary flow porometry method has confirmed the tortuous structure of PVC/PU fibrous membranes. Furthermore, the as-prepared membranes with high abrasion resistance (134 cycles) and comparable air permeability (154.1mm/s) showed fascinating filtration efficiency (99.5%) and low pressure drop (144 Pa) performance for 300-500 nm sodium chloride aerosol particles, suggesting their use as a promising medium for variety of potential applications in air filtration. PMID:23489615

Wang, Na; Raza, Aikifa; Si, Yang; Yu, Jianyong; Sun, Gang; Ding, Bin

2013-05-15

408

Impregnation of implantable polypropylene mesh with S-nitrosoglutathione-loaded poly(vinyl alcohol).  

PubMed

Clinical complications of implantable polypropylene (PP) meshes used to repair urinary incontinence and vaginal prolapse may be associated with their low surface energy and consequent poor tissue integration. For improving tissue integration, we impregnated monofilament PP meshes with physically crosslinked poly(vinyl alcohol) (PVA), resulting in PVA deposits tightly attached inside the knot spaces of the PP knit. While preserving the mesh porosity, the PVA deposits acted as an array of hydrophilic regions leading to a great increase in the overall mesh wettability, reflected by a contact angle decrease from 111 to ca. 66°. The PVA deposits were also used as reservoirs for the local release of S-nitrosoglutathione (GSNO), a nitric oxide (NO) donor. Plain and impregnated PP meshes (1.0cm×1.0cm) were implanted in the subcutaneous tissue of 21 adult female Wistar rats. Histological analysis of the abdominal wall 21 days after the surgeries revealed lower edema and greater angiogenesis while a marked decrement of NOx concentration in the tissue surrounding the impregnated meshes was observed after 2 days. These results indicate that PVA and PVA/GSNO impregnation might be a new strategy for decreasing the frequency of mesh extrusion after PP mesh implants. PMID:23545088

Prudente, Alessandro; Riccetto, Cássio Luís Zanettini; Simões, Maíra Martins de Souza Godoy; Pires, Bruno Morandi; de Oliveira, Marcelo Ganzarolli

2013-08-01

409

Thermal, mechanical and dielectric properties of poly(vinyl alcohol)/graphene oxide composites  

NASA Astrophysics Data System (ADS)

In this work the composite films of poly(vinyl alcohol) (PVA) doped with functionalized Graphene Oxide (GO) were prepared by solution casting method. The films were characterized using FT-IR, DSC, XRD, mechanical properties and dielectric studies at room temperature. FTIR spectra shows the formation of hydrogen bonds between hydroxyl groups of PVA and the hydroxy groups of GO. The DSC thermograms shows the addition of GO to PVA greatly improves the thermal stability of the composites. XRD patterns shows that the GO exfoliated and uniformly dispersed in PVA matrix. Mechanical properties are significantly improved in PVA/GO composites. The tensile strength increased from 8.2 to 13.7 MPa and the Young's modulus increased from 7.5 to 24.8 MPa for 5 wt% GO doped sample. Dielectric spectroscopy showed a highest dielectric constant for the 5 wt% GO doped PVA films. This work provides a potential design strategy on PVA/GO composite, which would lead to higher-performance, flexible dielectric materials, high charge-storage devices.

Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.; Naik, Jagadish

2014-04-01

410

Fabrication of photo responsive multi-bilayered film consisting of azobenzene containing copolymers and polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

In this study, faster response speed of ON/OFF switching of multi-bilayered films containing azo-functionalized polymer liquid crystal and polyvinyl alcohol, PVA, is investigated. The multi-bilayered films were found to reflect a light of specific wavelength, and showed reversible change in the reflection intensity by irradiation with non-polarized visible light and UV light. The multi-bilayered film having high absorbance around 300-500 nm due to stacking several decades of azobenzene containing layer. So, the change in reflection intensity of multi-bilayered film takes long time by light irradiation. We synthesized polyacrylates copolymers with azobenzene and biphenyl side chains where biphenyl groups is having no absorbance at UV and visible region. Multi-bilayered films were fabricated by spin-coating method and the switching time of reflection was investigated comparing to the multi-bilayered film containing azobenzene homopolymer, the ON switching times of reflection for the copolymers were faster than homopolymer needing 900 s. It is attributed to that inducing UV light (? = 365 nm) easily entered into the film by introducing of biphenyl groups.

Yagi, Ryohei; Kuwahara, Yutaka; Iwamoto, Hiroyuki; Kim, Sun-Nam; Ogata, Tomonari; Kurihara, Seiji

2014-02-01

411

Adsorption properties of polyvinyl-alcohol-grafted particles toward genistein driven by hydrogen-bond interaction.  

PubMed

The adsorption properties of polyvinyl alcohol (PVA)-grafted silica gel particles PVA/SiO2 toward genistein are researched in this paper. The effects of the main factors on the adsorption properties are investigated, the adsorption mechanism is explored in depth, and the adsorption thermodynamics is researched. The experimental results show that the conventional hydrogen bond is formed between the hydroxyl groups with high density on the surfaces of PVA/SiO2 and the phenolic hydroxyl groups in genistein, while ?-type hydrogen bond is formed between the hydroxyl groups of PVA/SiO2 and the conjugated aromatic rings. It is the two types of hydrogen bond that make the functional composite particles PVA/SiO2 produce very strong physical adsorption toward genistein. The competitive adsorption of the solvent can have severe negative impact on the adsorption capacity of genistein. Increasing temperature will weaken the hydrogen-bond interaction between PVA/SiO2 particles and genistein. The existence of electrolytes in the protic solvent will affect the adsorption negatively. The adsorption process of PVA/SiO2 particles toward genistein is exothermic and driven by enthalpy. The adsorption isotherm data matches the Langmuir model. PMID:23590345

Zhang, Yanyan; Gao, Baojiao; Xu, Zeqing

2013-05-01

412

Fabrication of porous chitosan-polyvinyl pyrrolidone scaffolds from a quaternary system via phase separation.  

PubMed

Three-dimensional porous chitosan-polyvinyl pyrrolidone (PVP) scaffolds were fabricated for tissue engineering applications via liquid-liquid or liquid-solid phase separation. A mixture of an acidic aqueous solution with butanol as a non-solvent and a chitosan-PVP quaternary system were freeze-dried. We then studied the homogenous open pore structure and the minute pore distribution in order to improve the mass transfer and cell seeding efficiency while also obtaining the optimal ratio of PVP to provide high interconnectivity and to improve the open-pore structure. The properties of the porous chitosan-PVP scaffolds - including the microstructure, chemical release, water absorption properties, and cell proliferation tests were studied - and the results were compared against those obtained from conventional scaffolds. chitosan-PVP scaffolds with a porosity of over 70% were obtained, and the pore morphology on the surface and within the porous scaffolds showed the presence of homogenous open pores with excellent interconnectivity. As the PVP content increased, main pores (50-100 ?m) and minute pores (4-10 ?m) could be clearly observed. Also, the porous scaffold showed an improved efficiency for cell adhesion after the cells were cultured for 4 h. After 72 h, the cultured cells presented an increase in the cell proliferation and on the porous scaffolds. These results strongly suggest that the porous chitosan-PVP scaffolds can be widely used in tissue engineering, including for biopatches and artificial skin applications. PMID:25410721

Lim, Jin Ik; Im, Heejung; Lee, Woo-Kul

2015-01-01

413

Thermochemical reaction mechanism of lead oxide with poly(vinyl chloride) in waste thermal treatment.  

PubMed

Poly(vinyl chloride) (PVC) as a widely used plastic that can promote the volatilization of heavy metals during the thermal treatment of solid waste, thus leading to environmental problems of heavy metal contamination. In this study, thermogravimetric analysis (TGA) coupled with differential scanning calorimeter, TGA coupled with Fourier transform infrared spectroscopy and lab-scale tube furnace experiments were carried out with standard PVC and PbO to explicate the thermochemical reaction mechanism of PVC with semi-volatile lead. The results showed that PVC lost weight from 225 to 230°C under both air and nitrogen with an endothermic peak, and HCl and benzene release were also detected. When PbO was present, HCl that decomposed from PVC instantly reacted with PbO via an exothermal gas-solid reaction. The product was solid-state PbCl2 at <501°C, which was the most volatile lead-containing compound with a low melting point and high vapor pressure. At >501°C, PbCl2 melted, volatilized and transferred into flue gas or condensed into fly ash. Almost all PbCl2 volatilized above 900°C, while PbO just started to volatilize slowly at this temperature. Therefore, the chlorination effect of PVC on lead was apt to lower-temperature and rapid. Without oxygen, Pb2O was generated due to the deoxidizing by carbon, with oxygen, the amount of residual Pb in the bottom ash was significantly decreased. PMID:25150687

Wang, Si-Jia; Zhang, Hua; Shao, Li-Ming; Liu, Shu-Meng; He, Pin-Jing

2014-12-01

414

Occupational lead exposure in Finland. IV. The polyvinyl chloride plastic industry.  

PubMed

One hundred and fifty-two workers from ten polyvinyl chloride (PVC) plastic factories were studied for lead exposure. Blood lead (Pb-B) concentration was measured for all the workers, urinary delta-aminolevulinic acid (ala) for 130 workers, erythrocyte alpha-aminolevulinic acid dehydratase (ala-d) activity for 59 workers, and blood hemoglobin concentration or 93 workers. The median Pb-B for all the workers was 37 mug/100 ml, and the highest median found for one factory was 63 mug/100 ml. The highest single Pb-B value found was 126 mug/100 ml. The jobs with the heaviest lead exposure were those of mixing and weighing lead stearate powder. It is assumed that replacing the powder with a granule form of lead stearate will diminish the hazard of lead exposure in the future. Urinary ALA concentrations and erythrocyte ALA-D activities corresponded well with the Pb-B concentration, but the hemoglobin values did not show any relation to lead exposure. It is concluded that in the PVC plastic industry of Finland the risk of exposure to lead is high and regular health examinations should be performed. PMID:1228897

Tola, S

1975-09-01

415

Case report of occupational asthma induced by polyvinyl chloride and nickel.  

PubMed

Polyvinyl chloride (PVC) is a widely used chemical for production of plastics. However occupational asthma (OA) caused by PVC has been reported only rarely. We report a 34-yr-old male wallpaper factory worker with OA due to PVC and nickel (Ni) whose job was mixing PVC with plasticizers. He visited the emergency room due to an asthma attack with moderate airflow obstruction and markedly increased sputum eosinophil numbers. A methacholine challenge test was positive (PC20 2.5 mg/mL). Bronchoprovocation tests with both PVC and Ni showed early and late asthmatic responses, respectively. Moreover, the fractional concentration of exhaled nitric oxide (FeNO) was increased after challenge with PVC. To our knowledge, this is the first case of OA in Korea induced by exposure to both PVC and Ni. We suggest that eosinophilic inflammation may be involved in the pathogenesis of PVC-induced OA and that FeNO monitoring can be used for its diagnosis. PMID:24133363

Song, Ga-Won; Ban, Ga-Young; Nam, Young-Hee; Park, Hae-Sim; Ye, Young-Min

2013-10-01

416

Case Report of Occupational Asthma Induced by Polyvinyl Chloride and Nickel  

PubMed Central

Polyvinyl chloride (PVC) is a widely used chemical for production of plastics. However occupational asthma (OA) caused by PVC has been reported only rarely. We report a 34-yr-old male wallpaper factory worker with OA due to PVC and nickel (Ni) whose job was mixing PVC with plasticizers. He visited the emergency room due to an asthma attack with moderate airflow obstruction and markedly increased sputum eosinophil numbers. A methacholine challenge test was positive (PC20 2.5 mg/mL). Bronchoprovocation tests with both PVC and Ni showed early and late asthmatic responses, respectively. Moreover, the fractional concentration of exhaled nitric oxide (FeNO) was increased after challenge with PVC. To our knowledge, this is the first case of OA in Korea induced by exposure to both PVC and Ni. We suggest that eosinophilic inflammation may be involved in the pathogenesis of PVC-induced OA and that FeNO monitoring can be used for its diagnosis. PMID:24133363

Song, Ga-Won; Ban, Ga-Young; Nam, Young-Hee; Park, Hae-Sim

2013-01-01

417

Preparation and properties of nanometer silk fibroin peptide/polyvinyl alcohol blend films for cell growth.  

PubMed

Nanometer silk fibroin peptide (Nano-SFP) was prepared from silkworm cocoons through the process of dissolution, dialysis and enzymolysis. For comparison, silk fibroin was decomposed with ?-chymotrypsin, trypsin and neutrase, respectively. From the SEM and particle size analysis results, the Nano-SFP prepared by neutrase was found to be the most desirable at about 50-200 nm. Nano-SFP/polyvinyl alcohol films (Nano-SFP/PVA) were prepared by blending Nano-SFP and PVA in water with different weight ratios of 10/90, 20/80, 30/70, and 40/60. The films were characterized by IR, SEM, TG, DSC and tensile strength test for investigating their structure, surface morphology, thermostability, and mechanical property. The results showed that Nano-SFP inserted in the PVA films with small linear particles, and Nano-SFP/PVA films exhibited smooth surface, good thermostability and tensile strength. The growth of Chinese hamster ovary (CHO) cells on films with and without Nano-SFP was investigated with MTT colorimetric assay to assess the films' ability to promote cell growth. It was observed that the Nano-SFP improved cell adhesion on the film surface, and the ability of promoting cell growth increased with the increasing content of Nano-SFP in the blend films. Nano-SFP/PVA film with the ratio of 30/70 was concluded to have the best properties. PMID:23831539

Luo, Qin; Chen, Zhongmin; Hao, Xuefei; Zhu, Qiangsong; Zhou, Yucheng

2013-10-01

418

Physicochemical and morphological properties of plasticized poly(vinyl alcohol)-agar biodegradable films.  

PubMed

The effects of the addition of glycerol (GLY) on the physicochemical and morphological properties of poly(vinyl alcohol) (PVA)-agar films were reported. PVA-agar films were prepared by solution cast method, and the addition of GLY in PVA-agar films altered the optical properties, resulting in a decrease in opacity values and in the color difference (?E) of the films. Structural characterization using Fourier transformation infrared (FTIR) spectroscopy and X-ray diffraction (XRD) indicated that the presence of GLY altered the intensity of the bands (from 1200 to 800cm(-1)) and crystallinity. The characterization of the thermal properties indicated that an increase in the agar content produces a decrease in the melting temperature and augments the heat of fusion. Similar tendencies were observed in plasticized films, but at different magnification. The formulation that demonstrated the lowest mechanical properties contained 25wt.% agar, whereas the formulation that contained 75wt.% agar demonstrated a significant improvement. The water vapor transmission rate (WVTR) and surface morphology analysis demonstrated that the structure of PVA-agar films is reorganized upon GLY addition. The physicochemical properties of PVA-agar films using GLY as a plasticizer provide information for the application of this formulation as packaging material for specific food applications. PMID:24875313

Madera-Santana, T J; Freile-Pelegrín, Y; Azamar-Barrios, J A

2014-08-01

419

Zuclopenthixol acetate for acute schizophrenia and similar serious mental illnesses  

PubMed Central

Background Medication used for acute aggression in psychiatry must have rapid onset of effect, low frequency of administration and low levels of adverse effects. Zuclopenthixol acetate is said to have these properties. Objectives To estimate the clinical effects of zuclopenthixol acetate for the management of acute aggression or violence thought to be due to serious mental illnesses, in comparison to other drugs used to treat similar conditions. Search methods We searched the Cochrane Schizophrenia’s Group Trials Register (July 2011). We supplemented this by citation searching and personal contact with authors and relevant pharmaceutical companies. Selection criteria All randomised clinical trials involving people thought to have serious mental illnesses comparing zuclopenthixol acetate with other drugs. Data collection and analysis Two review authors extracted and cross-checked data independently. We calculated fixed-effect relative risks (RR) and 95% confidence intervals (CI) for dichotomous data. We analysed by intention-to-treat. We used mean differences (MD) for continuous variables. Main results We found no data for the primary outcome, tranquillisation. Compared with haloperidol, zuclopenthixol acetate was no more sedating at two hours (n = 40, 1 RCT, RR 0.60, 95% CI 0.27 to 1.34). People given zuclopenthixol acetate were not at reduced risk of being given supplementary antipsychotics (n = 134, 3 RCTs, RR 1.49, 95% CI 0.97 to 2.30) although additional use of benzodiazepines was less (n = 50, 1 RCT, RR 0.03, 95% CI 0.00 to 0.47). People given zuclopenthixol acetate had fewer injections over seven days compared with those allocated to haloperidol IM (n = 70, 1 RCT, RR 0.39, 95% CI 0.18 to 0.84, NNT 4, CI 3 to 14). We found no data on more episodes of aggression or harm to self or others. One trial (n = 148) reported no significant difference in adverse effects for people receiving zuclopenthixol acetate compared with those allocated haloperidol at one, three and six days (RR 0.74, 95% CI 0.43 to 1.27). Compared with haloperidol or clotiapine, people allocated zuclopenthixol did not seem to be at more risk of a range of movement disorders (< 20%). Three studies found no difference in the proportion of people getting blurred vision/dry mouth (n = 192, 2 RCTs, RR at 24 hours 0.90, 95% CI 0.48 to 1.70). Similarly, dizziness was equally infrequent for those allocated zuclopenthixol acetate compared with haloperidol (n = 192, 2 RCTs, RR at 24 hours 1.15, 95% CI 0.46 to 2.88). There was no difference between treatments for leaving the study before completion (n = 522, RR 0.85, 95% CI 0.31 to 2.31). One study reported no difference in adverse effects and outcome scores, when high dose (50-100 mg/injection) zuclopenthixol acetate was compared with low dose (25-50 mg/injection) zuclopenthixol acetate. Authors’ conclusions Recommendations on the use of zuclopenthixol acetate for the management of psychiatric emergencies in preference to ‘standard’ treatment have to be viewed with caution. Most of the small trials present important methodological flaws and findings are poorly reported. This review did not find any suggestion that zuclopenthixol acetate is more or less effective in controlling aggressive acute psychosis, or in preventing adverse effects than intramuscular haloperidol, and neither seemed to have a rapid onset of action. Use of zuclopenthixol acetate may result in less numerous coercive injections and low doses of the drug may be as effective as higher doses. Well-conducted pragmatic randomised controlled trials are needed. PMID:22513898

Jayakody, Kaushadh; Gibson, Roger Carl; Kumar, Ajit; Gunadasa, Shalmini

2014-01-01

420

(Conversion of acetic acid to methane by thermophiles: Progress report)  

SciTech Connect

The objective of this project is to provide an understanding of thermophilic anaerobic microorganisms capable of breaking down acetic acid, the precursor of two-thirds of the methane produced by anaerobic bioreactors. Recent results include: (1) the isolation of Methanothrix strain CALLS-1, which grows much more rapidly than mesophilic strains; (2) the demonstration that thermophilic cultures of Methanosarcina and Methanothrix show minimum thresholds for acetate utilization of 1--2.5 mM and 10--20{mu}m respectively, in agreement with ecological data indicating that Methanothrix is favored by low acetate concentration; (3) the demonstration of high levels of thermostable acetyl-coA synthetase and carbon monoxide dehydrogenase in cell-free extracts of Methanothrix strains CALS-1; (4) the demonstration of methanogenesis from acetate and ATP in cell free extracts of strain CALS-1. (5) the demonstration that methanogenesis from acetate required 2 ATP/methane, and, in contrast to Methanosarcina, was independent of hydrogen and other electron donors; (6) the finding that entropy effects must be considered when predicting the level of hydrogen in thermophilic syntrophic cultures. (7) the isolation and characterization of the Desulfotomaculum thermoacetoxidans. Current research is centered on factors which allow thermophilic Methanothrix to compete with Methanosarcina.

Zinder, S.

1991-01-01

421

[Conversion of acetic acid to methane by thermophiles: Progress report  

SciTech Connect

The objective of this project is to provide an understanding of thermophilic anaerobic microorganisms capable of breaking down acetic acid, the precursor of two-thirds of the methane produced by anaerobic bioreactors. Recent results include: (1) the isolation of Methanothrix strain CALLS-1, which grows much more rapidly than mesophilic strains; (2) the demonstration that thermophilic cultures of Methanosarcina and Methanothrix show minimum thresholds for acetate utilization of 1--2.5 mM and 10--20{mu}m respectively, in agreement with ecological data indicating that Methanothrix is favored by low acetate concentration; (3) the demonstration of high levels of thermostable acetyl-coA synthetase and carbon monoxide dehydrogenase in cell-free extracts of Methanothrix strains CALS-1; (4) the demonstration of methanogenesis from acetate and ATP in cell free extracts of strain CALS-1. (5) the demonstration that methanogenesis from acetate required 2 ATP/methane, and, in contrast to Methanosarcina, was independent of hydrogen and other electron donors; (6) the finding that entropy effects must be considered when predicting the level of hydrogen in thermophilic syntrophic cultures. (7) the isolation and characterization of the Desulfotomaculum thermoacetoxidans. Current research is centered on factors which allow thermophilic Methanothrix to compete with Methanosarcina.

Zinder, S.

1991-12-31

422

Reduction of aerobic acetate production by Escherichia coli.  

PubMed Central

Acetate excretion by Escherichia coli during aerobic growth on glucose is a major obstacle to enhanced recombinant protein production. We report here that the fraction of carbon flux through the anaplerotic pathways is one of the factors influencing acetate excretion. Flux analysis of E. coli central metabolic pathways predicts that increasing the fraction of carbon flux through the phosphoenolpyruvate carboxylase (PPC) pathway and the glyoxylate bypass reduces acetate production. We tested this prediction by overexpressing PPC and deregulating the glyoxylate bypass by using a fadR strain. Results show that the acetate yield by the fadR strain with PPC overexpression is decreased more than fourfold compared to the control, while the biomass yield is relatively unaffected. Apparently, the fraction of carbon flux through the anaplerotic pathways is one of the factors that influence acetate excretion. These results confirm the prediction of our flux analysis and further suggest that E. coli is not fully optimized for efficient utilization of glucose. PMID:9251207

Farmer, W R; Liao, J C

1997-01-01

423

Probing reaction pathways on model catalyst surfaces: Vinyl acetate synthesis and olefin metathesis  

Microsoft Academic Search

The reaction pathway for the palladium-catalyzed synthesis of vinyl acetate from acetic acid, ethylene and oxygen is investigated using reflection–absorption infrared spectroscopy by monitoring the rate of acetate titration by gas-phase ethylene. This reveals that acetate species are removed by reaction with gas-phase ethylene resulting in vinyl acetate formation. Reaction with C2D4 reveals a large (?6) isotope effect indicating that

Feng Gao; Yilin Wang; Florencia Calaza; Dario Stacchiola; Wilfred T. Tysoe

2008-01-01

424

Quality testing of human albumin by capillary electrophoresis using thermally cross-linked poly(vinyl pyrrolidone)-coated fused-silica capillary.  

PubMed

To detect the quality of medicinal human albumin by capillary electrophoresis, we produced a fused-silica capillary coated with thermally cross-linked poly(vinyl pyrrolidone) to prohibit protein adsorption. This type of capillary was easily obtained by injecting an aqueous poly(vinyl pyrrolidone) solution into a fused-silica capillary and thermally annealing it at 200°C. Notably, stable and low electro-osmotic flow was obtained in the poly(vinyl pyrrolidone)-coated capillary at pH 2.20-9.00, and the separation of a mixture of four basic proteins indicated that the poly(vinyl pyrrolidone)-coated capillary exhibits excellent repeatability and separation efficiency; moreover, the separation of these four basic proteins could even be achieved at pH 7.00. The protein recovery percentage of human serum albumin in a single-protein solution and a mixed blood proteins solution was determined to be 97.03 and 95.40% in the poly(vinyl pyrrolidone)50-3 (representing the concentration of the capillary-injected poly(vinyl pyrrolidone) aqueous solution, 50 mg/mL, and thermal annealing time, 3 h) capillary, respectively. Based on these results, we used the poly(vinyl pyrrolidone)50-3 -coated capillary to quantify the protein content of human albumin, and the results obtained from run to run, day to day and capillary to capillary demonstrated that the coated capillary could be used for quality testing commercially available human albumin. PMID:25113845

Tan, Lin; Zheng, Xiajun; Chen, Lijuan; Wang, Yanmei

2014-10-01

425

[Conversion of acetic acid to methane by thermophiles  

SciTech Connect

The primary goal of this project is to obtain a better understanding of thermophilic microorganisms which convert acetic acid to CH[sub 4]. The previous funding period represents a departure from earlier research in this laboratory, which was more physiological and ecological. The present work is centered on the biochemistry of the thermophile Methanothrix sp. strain CALS-1. this organism presents a unique opportunity, with its purity and relatively rapid growth, to do comparative biochemical studies with the other major acetotrophic genus Methanosarcina. We previously found that Methanothrix is capable of using acetate at concentrations 100 fold lower than Methanosarcina. This finding suggests that there are significant differences in the pathways of methanogenesis from acetate in the two genera.

Zinder, S.H.

1993-01-01

426

Characterization of acetic acid bacteria in "traditional balsamic vinegar".  

PubMed

This study evaluated the glucose tolerance of acetic acid bacteria strains isolated from Traditional Balsamic Vinegar. The results showed that the greatest hurdle to acetic acid bacteria growth is the high sugar concentration, since the majority of the isolated strains are inhibited by 25% of glucose. Sugar tolerance is an important technological trait because Traditional Balsamic Vinegar is made with concentrated cooked must. On the contrary, ethanol concentration of the cooked and fermented must is less significant for acetic acid bacteria growth. A tentative identification of the isolated strains was done by 16S-23S-5S rDNA PCR/RFLP technique and the isolated strains were clustered: 32 strains belong to Gluconacetobacter xylinus group, two strains to Acetobacter pasteurianus group and one to Acetobacter aceti. PMID:16214251

Gullo, Maria; Caggia, Cinzia; De Vero, Luciana; Giudici, Paolo

2006-02-01

427

Syntrophic acetate oxidation in industrial CSTR biogas digesters.  

PubMed

The extent of syntrophic acetate oxidation (SAO) and the levels of known SAO bacteria and acetate- and hydrogen-consuming methanogens were determined in sludge from 13 commercial biogas production plants. Results from these measurements were statistically related to the prevailing operating conditions, through partial least squares (PLS) analysis. This revealed that high abundance of microorganisms involved in SAO was positively correlated with relatively low abundance of aceticlastic methanogens and high concentrations of free ammonia (>160 mg/L) and volatile fatty acids (VFA). Temperature was identified as another influencing factor for the population structure of the syntrophic acetate oxidising bacteria (SAOB). Overall, there was a high abundance of SAOB in the different digesters despite differences in their operating parameters, indicating that SAOB are an enduring and important component of biogas-producing consortia. PMID:24333792

Sun, Li; Müller, Bettina; Westerholm, Maria; Schnürer, Anna

2014-02-10

428

Isothermal decomposition of gamma-irradiated palladium acetate  

NASA Astrophysics Data System (ADS)

The isothermal decomposition of un-irradiated (pristine) and pre-gamma-irradiated palladium acetate was studied in the temperature range (498-508 K) and in air using the isothermal thermogravimetric technique. The data were analysed using various solid state reaction models. The results showed that the kinetics of isothermal decomposition of palladium acetate was governed by random nucleation reaction (Erofe'ev equation A(3)). The activation energies of the main decomposition process for un-irradiated and pre-gamma-irradiated samples were calculated. The change in texture and crystal structure of the investigated palladium acetate by gamma-irradiation was studied using electron microscopy and X-ray diffraction techniques.

Mahfouz, R. M.; Alshehri, S. M.; Monshi, M. A. S.; Abd El-Salam, N. M.

2004-06-01

429

Delineation of LASIK Flaps with Prednisolone Acetate Eyedrops  

PubMed Central

We describe the use and safety of prednisolone acetate eyedrops at the end of laser in situ keratomileusis (LASIK) to aid proper positioning of the corneal flap. The LASIK flap is created using the preferred technique. Following laser ablation and flap repositioning, one drop of prednisolone acetate is instilled on the eye. This delineates the flap “gutters” and allows perfect flap positioning and centration. We used this technique in 425 eyes undergoing LASIK for correction of spherocylindrical refractive errors. Flap margins were adequately delineated intraoperatively. The only complication related to the use of the steroid suspension was crystal deposition under the flap in one case which resolved completely in 48 hours. PMID:24982743

Fahd, Daoud C; Fahed, Sharbel D

2014-01-01

430

Abiraterone Acetate and Castration Resistant Ductal Adenocarcinoma of the Prostate  

PubMed Central

Ductal adenocarcinoma of the prostate is a rare histological variant that only represents <1% of prostate tumors. This histological variant has several important clinical implications with respect to their evolution, clinical prognosis, and treatment. We report the case of a 64-year-old patient with ductal adenocarcinoma of the prostate, which progresses to castration-resistant prostate cancer, that was treated with abiraterone acetate with good clinical response, to our knowledge, the first case of ductal adenocarcinoma of the prostate in treatment with abiraterone acetate. PMID:24891969

Linden-Castro, Edgar; Pelayo-Nieto, Marcela; Alias-Melgar, Alejandro; Espinosa-Perezgrovas, Daniel; Ramirez-Galindo, Ivan; Catalan-Quinto, Gabriel

2014-01-01

431

Fate and residues of trenbolone acetate in edible tissues from sheep amd calves implanted with tritium-labeled trenbolone acetate  

SciTech Connect

In order to study the fate and residues of trenbolone acetate in edible tissues, two groups of six animals from two ruminant species (ewes and calves) were implanted with (3H)trenbolone acetate. The distribution of extractable radioactive residues was measured in liver, kidney and muscle. We found that the largest proportion of residues was not extractable and thus was considered as covalently bound residues. The proportion of the main extractable metabolites (17 alpha-trenbolone, trendione, 17 beta-trenbolone) was measured. The evaluation of the distribution of trenbolone acetate metabolites directly soluble in water showed that unknown metabolite(s) were predominant. The covalent binding to nucleic acids was measured. It was so low that it was not detectable. The results are discussed in light of the data presented in the scientific report on anabolic agents in animal production from the European scientific working group.

Evrard, P.; Maghuin-Rogister, G.; Rico, A.G. (Univ. of Liege (Belgium))

1989-06-01

432

Polyblends of Poly(vinyl alcohol) and Poly(Vegr;-caprolactone) and Their Properties  

NASA Astrophysics Data System (ADS)

The increasing volume of plastic has caused the serious problem in environment. One way to solve this problem is preparation of new plastic materials which can be decomposed by microorganisms in environment These plastics may be prepared from non-biodegradable material by modification of theirs physical and chemical properties, preparation of theirs copolymers and polyblends. The main problem in preparation of polyblends is compatibility between polymers mixtures. In this work has focused on preparation of polyblends between poly(vinyl alcohol) (PVA) and poly(?-caprolactone) (PCL) in various compositions by casting of polymers solution. Characterizations of polyblends were carried out by analysis of functional groups (FTIR), thermal property (DSC and TGA/DTA), mechanical properties (Tensile tester), and crystallinity (XRD). The results of polyblends showed that the compatible and homogeneous polyblends were obtained in solvent composition (dimethyl sulfoxide/tetrahydrofurane) (DMSO/THF) of 3:1 and PCL ratio in polyblends less than 15 % (w/w). The absorption intensity of carbonyl and alkyl groups observed in 1725 cm-1 and 2940 cm-1 increased with increasing PCL composition in polyblends. The melting point (Tm) and fusion enthalpy (?Hm) for PCL region in polyblends decreased with decreasing PCL composition, but melting point (Tm) and fusion of enthalpy (?Hm) for PVA region increased. The total fusion enthalpy value obtained by observation was smaller than that of calculation value, indicating the presence of interaction between PCL and PVA to form a part of compatible polyblends with more amorphous structure. The mechanical properties of polyblends tended to decrease with increasing PCL ratio in polyblends. These results were supported by analysis of crystallinity with using X-ray diffraction.

Arcana, I. M.; Alio, L.

2008-03-01

433

Leaching of diethylhexyl phthalate from polyvinyl chloride containers by selected drugs and formulation components.  

PubMed

The extent of leaching of diethylhexyl phthalate (DEHP) from polyvinyl chloride (PVC) bags by several organic solvents and surfactants used as formulation components and by 12 drug products containing these solvents and surfactants was studied. The organic solvents ethanol, polyethylene glycol, and propylene glycol, the surfactants polysorbate 80 and polyoxyethylated castor oil, and the 12 drugs were admixed separately in PVC bags of 5% dextrose injection. At the time of preparation and after 4, 8, and 24 hours at 24 degrees C, the concentration of DEHP in duplicate samples was determined in duplicate by high-performance liquid chromatography. Ethanol, polyethylene glycol, and propylene glycol at concentrations of 25% and the drugs containing these components did not leach DEHP within the study period. Polysorbate 80 1% to 25% leached detectable amounts of DEHP in as little as one hour at the high concentration and within four hours at the lower concentrations; at 24 hours, DEHP concentrations ranged from 36 micrograms/mL for 1% polysorbate 80 to 237 micrograms/mL for 25% polysorbate 80. Similar results were observed for polysorbate 80 plus ethanol and for polyoxyethylated castor oil plus ethanol. Drug products containing surfactants, including cyclosporine, miconazole, and teniposide, and the vehicles used in formulating taxol and taxotere, leached relatively large amounts of DEHP in 24 hours. Smaller amounts were leached by chlordiazepoxide hydrochloride and etoposide. DEHP was leached from PVC containers by a variety of surfactants and drug products containing these surfactants. Drugs that leach DEHP should be prepared in non-PVC containers and administered through non-PVC tubing. PMID:8362871

Pearson, S D; Trissel, L A

1993-07-01

434

Elastic properties of thin poly(vinyl alcohol)-cellulose nanocrystal membranes.  

PubMed

In spite of extensive studies on the preparation and characterization of nanocomposite materials, the correlation of their properties at the nanoscale with those in bulk is a relatively unexplored area. This is of great importance, especially for materials with potential biomedical applications, where surface properties are as important in determining their applicability as bulk characteristics. In this study, the nanomechanical characteristics of thin poly(vinyl alcohol) (PVOH)-poly(acrylic acid) (PAA)-cellulose nanocrystal (CNC) membranes were studied using the nanoindentation module in an atomic force microscope (AFM) and the properties were compared with the macro-scale properties obtained by tensile tests. In general, the elastic properties measured by nanoindentation followed the same trend as macro-scale tensile tests except for the PVOH 85-PAA 0-CNC 15 sample. In comparison to the macro-scale elastic properties, the measured elastic moduli with AFM were higher. Macro-scale tensile test results indicated that, in the presence of PAA, incorporation of CNCs up to 20 wt% improved the elastic modulus of PVOH, but when no PAA was added, increasing the CNC content above 10 wt% resulted in their agglomeration and degradation in mechanical properties of PVOH. The discrepancy between macro-scale tensile tests and nanoindentation in the PVOH 85-PAA 0-CNC 15 sample was correlated to the high degree of inhomogeneity of CNC dispersion in the matrix. It was found that the composites reinforced with cellulose nanocrystals had smaller indentation imprints and the pile-up effect increased with the increase of cellulose nanocrystal content. PMID:22293708

Pakzad, A; Simonsen, J; Yassar, R S

2012-02-01

435

Plasticizers Increase Adhesion of the Deteriogenic Fungus Aureobasidium pullulans to Polyvinyl Chloride  

PubMed Central

Initial adhesion of fungi to plasticized polyvinyl chloride (pPVC) may determine subsequent colonization and biodeterioration processes. The deteriogenic fungus Aureobasidium pullulans was used to investigate the physicochemical nature of adhesion to both unplasticized PVC (uPVC) and pPVC containing the plasticizers dioctyl phthalate (DOP) and dioctyl adipate (DOA). A quantitative adhesion assay using image analysis identified fundamental differences in the mechanism of adhesion of A. pullulans blastospores to these substrata. Adhesion to pPVC was greater than that to uPVC by a maximum of 280% after a 4-h incubation with 108 blastospores ml?1. That plasticizers enhance adhesion to PVC was confirmed by incorporating a dispersion of both DOA and DOP into the blastospore suspension. Adhesion to uPVC was increased by up to 308% in the presence of the dispersed plasticizers. Hydrophobic interactions were found to dominate adhesion to uPVC because (i) a strong positive correlation was observed between substratum hydrophobicity (measured by using a dynamic contact angle analyzer) and adhesion to a range of unplasticized polymers including uPVC, and (ii) neither the pH nor the electrolyte concentration of the suspension buffer, both of which influence electrostatic interactions, affected adhesion to uPVC. In contrast, adhesion to pPVC is principally controlled by electrostatic interactions. Enhanced adhesion to pPVC occurred despite a relative reduction of 13° in the water contact angle of pPVC compared to that of uPVC. Furthermore, adhesion to pPVC was strongly dependent on both the pH and electrolyte concentration of the suspension medium, reaching maximum levels at pH 8 and with an electrolyte concentration of 10 mM NaCl. Plasticization with DOP and DOA therefore increases adhesion of A. pullulans blastospores to pPVC through an interaction mediated by electrostatic forces. PMID:10427051

Webb, Jeremy S.; Van der Mei, Henny C.; Nixon, Marianne; Eastwood, Ian M.; Greenhalgh, Malcolm; Read, Simon J.; Robson, Geoffrey D.; Handley, Pauline S.

1999-01-01

436

Mercury transformation and distribution across a polyvinyl chloride (PVC) production line in China.  

PubMed

The production of polyvinyl chloride (PVC) via the calcium carbide process utilizes a catalyst containing large amounts of mercury (Hg) and is therefore one of the most important sources of anthropogenic Hg in China. To measure the emission of Hg from PVC production, we established a flowchart for the calcium carbide process, for which we quantified the Hg content of the material/product at each step. Results indicated that 71.5% of the total Hg (Hg(T)) was lost from the catalyst, most of which was recovered by the Hg remover, accounting for 46.0% of the total Hg (Hg(T)). We determined that 3.7% of the Hg(T) was released into the environment, mostly in solid wastes and byproducts such as hydrochloric acid. Furthermore, no Hg has been detected in the PVC end product. However, we were only able to account for 78.1% of the Hg across the whole system, leaving 21.7% unaccounted for in the mass balance. A rough estimation indicates that most of the "missing" Hg had accumulated in deposits on the inner surface of converters and downstream pipelines; however, the emission to the atmosphere was ? 1% of the Hg(T). For a PVC production line equipped with a Hg remover, emissions of Hg to the atmosphere have been estimated to be 4.9 g per tonne PVC. Currently, almost all calcium carbide facilities have been equipped with a Hg remover, which may reduce the release of Hg in China by ? 500 t/year. PMID:24428761

Ren, Wen; Duan, Lei; Zhu, Zhenwu; Du, Wen; An, Zhongyi; Xu, Lingjun; Zhang, Chi; Zhuo, Yuqun; Chen, Changhe

2014-02-18

437

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

PubMed

The need for protozoa for the proliferation of Legionella pneumophila in aquatic habitats is still not fully understood and is even questioned by some investigators. This study shows the in vivo growth of L. pneumophila in protozoa in aquatic biofilms developing at high concentrations on plasticized polyvinyl chloride in a batch system with autoclaved tap water. The inoculum, a mixed microbial community including indigenous L. pneumophila originating from a tap water system, was added in an unfiltered as well as filtered (cellulose nitrate, 3.0-microm pore size) state. Both the attached and suspended biomasses were examined for their total amounts of ATP, for culturable L. pneumophila, and for their concentrations of protozoa. L. pneumophila grew to high numbers (6.3 log CFU/cm2) only in flasks with an unfiltered inoculum. Filtration obviously removed the growth-supporting factor, but it did not affect biofilm formation, as determined by measuring ATP. Cultivation, direct counting, and 18S ribosomal DNA-targeted PCR with subsequent sequencing revealed the presence of Hartmannella vermiformis in all flasks in which L. pneumophila multiplied and also when cycloheximide had been added. Fluorescent in situ hybridization clearly demonstrated the intracellular growth of L. pneumophila in trophozoites of H. vermiformis, with 25.9% +/- 10.5% of the trophozoites containing L. pneumophila on day 10 and >90% containing L. pneumophila on day 14. Calculations confirmed that intracellular growth was most likely the only way for L. pneumophila to proliferate within the biofilm. Higher biofilm concentrations, measured as amounts of ATP, gave higher L. pneumophila concentrations, and therefore the growth of L. pneumophila within engineered water systems can be limited by controlling biofilm formation. PMID:15528550

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

2004-11-01

438

Evaluation of hydrophobic polyvinyl-alcohol formaldehyde sponges as absorbents for oil spill.  

PubMed

Macroporous materials are a class of absorbents used for oil spill cleanup. In this article, novel macroporous and hydrophobic polyvinyl formaldehyde (PVF-H) sponges were prepared by the reaction of stearoyl chloride with hydroxyl groups of hydrophilic PVF sponge at different temperatures. Attenuated total reflectance-infrared (ATR-IR) spectroscopy confirmed the successfully anchoring of hydrophobic stearoyl groups on the PVF networks. Scanning electron microscopy (SEM) images demonstrated that the as-prepared PVF-H had interconnected open-cell structures, and mercury intrusion porosimetry indicated that the average pore size ranged from 60 to 90 ?m and porosity was greater than 94.8%. Such PVF-H sponges can absorb oil products effectively, such as toluene, n-hexane, kerosene, soybean oil, hydraulic oil, and crude oil up to 13.7 g·g(-1) to 56.6 g·g(-1), and this level of absorption was approximately 2-4 times higher than that absorbed by commercial polypropylene nonwoven mat. In low-viscosity oils, the samples can reach the saturated absorption amount only in 1 min, but in higher-viscosity oils, absorption equilibrium can be reached in 10 min. In a simulated oil slick system, these macroporous and hydrophobic sponges can still maintain high oil absorption capacities within the range of 14.4 g·g(-1) to 57.6 g·g(-1), whereas a relatively low absorption rate (approximately 20 min) indicated high absorption performance and excellent selectivity in the oil-water mixture. In addition, the absorbed oils were collected effectively only through a simple squeeze. The PVF-H sponges were subjected to 35 absorption-squeeze cycles and exhibited good reusability and 90% recovery for oils. The samples prepared at different temperatures differed in their absorption capacities to some extent. However, this new kind of macroporous and PVF-H sponges had excellent absorption performance on oil products. PMID:24797603

Pan, Yanxiong; Shi, Kai; Peng, Chao; Wang, Weicai; Liu, Zhi; Ji, Xiangling

2014-06-11

439

Trisacryl Gelatin Microspheres Versus Polyvinyl Alcohol Particles in the Preoperative Embolization of Bone Neoplasms  

SciTech Connect

The aim of this study was to compare the efficacy of trisacryl gelatin microspheres versus polyvinyl alcohol particles (PVA) in the preoperative embolization of bone neoplasms, on the basis of intraoperative blood loss quantified by the differences in preoperative and postoperative hematic levels of hemoglobin, hematocrit and erythrocytes count. From January 1997 to December 2002, preoperative embolization of bone tumors (either primary or secondary) was carried out in 49 patients (age range 12/78), 20 of whom were treated with trysacril gelatin microspheres (group A) and 29 with PVA particles (group B). The delay between embolization and surgery ranged from 1 to 13 days in group A and 1 to 4 days in group B. As used in international protocols, we considered hematic levels of hemoglobin, hematocrit and erythrocytes count for the measurement of intraoperative blood loss then the differences in pre- and postoperative levels were used as statistical comparative parameters. We compared the values of patients treated with embospheres (n = 10) and PVA (n = 18) alone, and patients treated with (group A = 10; group B = 11) versus patients treated without other additional embolic materials in each group (group A = 10; group B = 18). According to the Student's t-test (p < 0.05), the difference of hematic parameters between patients treated by embospheres and PVA alone were significant; otherwise there was no significant difference between patients treated with only one embolic material (embospheres and PVA) versus those treated with other additional embolic agents in each group. The patients treated with microspheres had a minor quantification of intraoperative blood loss compared to those who received PVA particles. Furthermore, they had a minor increase of bleeding related to the delay time between embolization and surgery. The use of additional embolic material did not improve the efficacy of the procedure in either group of patients.

Basile, Antonio; Rand, Thomas; Lomoschitz, Fritz [University of Vienna Medical School, Division of Angiography and Interventional Radiology (Austria); Toma, Cyril [University of Vienna Medical School, Department of Orthopedic Surgery (Austria); Lupattelli, Tommaso [University of Perugia, Department of Radiology, Policlinico Monteluce (Italy); Kettenbach, Joachim; Lammer, Johannes [University of Vienna Medical School, Division of Angiography and Interventional Radiology (Austria)

2004-09-15

440

Poly(vinyl alcohol)-based film potentially suitable for antimicrobial packaging applications.  

PubMed

This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 ?m in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances. PMID:24611868

Musetti, Alessandro; Paderni, Katia; Fabbri, Paola; Pulvirenti, Andrea; Al-Moghazy, Marwa; Fava, Patrizia

2014-04-01

441

Povalibacter uvarum gen. nov., sp. nov., a polyvinyl-alcohol-degrading bacterium isolated from grapes.  

PubMed

Polyvinyl-alcohol-degrading bacteria were isolated from the fruit of a grape in Yokosuka, Japan. The isolated strain, Zumi 37(T), was a Gram-stain-negative, rod-shaped, motile, non-spore-forming and strictly aerobic chemo-organotroph, showing optimal growth at pH 7.5, 30 °C and 0.1% (w/v) NaCl. The major respiratory quinone was Q-8. The predominant fatty acids were iso-C(15?:?0), C(16?:?0) and C(16?:?1)?7c. The major polyamines were homospermidine and putrescine. The predominant polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content of the novel strain was 64.2 mol%. 16S rRNA gene sequence comparison revealed that strain Zumi 37(T) belongs to the family Sinobacteraceae within the class Gammaproteobacteria. Steroidobacter denitrificans DSM 18526(T) was the most closely related species with a validly published name, with 98.0% similarity based on 16S rRNA gene sequence comparison (and showed less than 87.5% sequence similarity to members of the genera Alkanibacter, Fontimonas, Hydrocarboniphaga, Nevskia and Solimonas with known 16S rRNA gene sequences). Phenotypes for growth under aerobic conditions and on complex media and major fatty acid composition, differed greatly from those of with comparatively high 16S rRNA gene sequence similarity. Based on phylogenetic, phenotypic and chemotaxonomic evidence, it is proposed that strain Zumi 37(T) represents a novel species in a new genus for which the name Povalibacter uvarum gen. nov., sp. nov. is proposed. The type strain of the type species is Zumi 37(T) (?=?JCM 18749(T)?=?DSM 26723(T)). PMID:24844263

Nogi, Yuichi; Yoshizumi, Masaki; Hamana, Koei; Miyazaki, Masayuki; Horikoshi, Koki

2014-08-01

442

Influence of Cr2O3 nanoparticles on the physical properties of polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

Nano-sized chromium oxide (Cr2O3) was synthesized by sol-gel method and mixed with polyvinyl alcohol (PVA) to produce nanocomposite films. Scanning electron microscopy (SEM) was used to observe the morphology and dispersion of Cr2O3 on the surface of the PVA films. X-ray diffraction (XRD) was performed on nano-sized Cr2O3, pure PVA, and Cr2O3/PVA composites. Based on the results of both XRD and high-resolution transmission electron microscopy (HR-TEM), the average particle size of the Cr2O3 was ? 46 nm. Differential scanning calorimetry (DSC) showed that the thermal stability and degree of crystallinity of the PVA were reinforced by the addition of Cr2O3 nanoparticles. The absorbance and extinction coefficients of the composites were studied in the UV-vis range and compared with those of pure PVA. The optical energy band gap, Eg, was calculated. Dielectric constant, ?', dielectric loss modulus, M?, and ac conductivity, ?ac, of all samples were measured within temperature and frequency ranges of 300-468 K and 10 kHz-2 MHz, respectively. According to the frequency and temperature dependence of the dielectric loss modulus, M?, the observed ?-relaxation peak was due to the micro-Brownian motion of the polymer main chains. The behavior of ?ac(f) for the composite films indicated that the conduction mechanism was correlated barrier hopping (CBH). The results of this work were discussed and compared with those of previous studies of PVA composites.

Hassen, A.; El Sayed, A. M.; Morsi, W. M.; El-Sayed, S.

2012-11-01

443

Rat Model of Hindlimb Ischemia Induced via Embolization with Polyvinyl Alcohol and N-Butyl Cyanoacrylate  

PubMed Central

Objective To investigate the feasibility of a rat model on hindlimb ischemia induced by embolization from the administration of polyvinyl alcohol (PVA) particles or N-butyl cyanoacrylate (NBCA). Materials and Methods Unilateral hindlimb ischemia was induced by embolization with NBCA (n = 4), PVA (n = 4) or surgical excision (n = 4) in a total of 12 Sprague-Dawley rats. On days 0, 7 and 14, the time-of-flight magnetic resonance angiography (TOF-MRA) and enhanced MRI were obtained as scheduled by using a 3T-MR scanner. The clinical ischemic index, volume change and degree of muscle necrosis observed on the enhanced MRI in the ischemic hindlimb were being compared among three groups using the analysis of variance. Vascular patency on TOF-MRA was evaluated and correlated with angiographic findings when using an inter-rater agreement test. Results There was a technical success rate of 100% for both the embolization and surgery groups. The clinical ischemic index did not significantly differ. On day 7, the ratios of the muscular infarctions were 0.436, 0.173 and 0 at thigh levels and 0.503, 0.337 and 0 at calf levels for the NBCA, PVA and surgery groups, respectively. In addition, the embolization group presented increased volume and then decreased volume on days 7 and 14, respectively. The surgery group presented a gradual volume decrease. Good correlation was shown between the TOF-MRA and angiographic findings (kappa value of 0.795). Conclusion The examined hindlimb ischemia model using embolization with NBCA and PVA particles in rats is a feasible model for further research, and muscle necrosis was evident as compared with the surgical model. PMID:24265568

Shin, Cheong-Il; Song, Yong Sub; Cho, Hye Rim; Lee, Kyoung-Bun; Lee, Whal; Jae, Hwan Jun; Chung, Jin Wook

2013-01-01

444

Soy proteins as environmentally friendly sizing agents to replace poly(vinyl alcohol).  

PubMed

An environmentally friendly and inexpensive substitute to the widely used poly(vinyl alcohol) (PVA) has been developed from soy proteins for textile warp sizing. Textile processing is the major source of industrial water pollution across the world, and sizing and desizing operations account for nearly 30 % of the water consumed in a textile plant. PVA is one of the most common sizing agents used for synthetic fibers and their blends due to PVA's easy water solubility and ability to provide desired sizing performance. However, PVA does not degrade and is a major contributor to pollution in textile effluent treatment plants. Although considerable efforts have been made to replace PVA with biodegradable sizing materials, the performance properties provided by PVA on synthetic fibers and their blends have been unmatched so far. Soy proteins are inexpensive, biodegradable, and have been widely studied for potential use in food packaging, as resins and adhesives. In this research, the potential of using soy proteins as textile sizing agents to replace PVA was studied. Polyester and polyester/cotton rovings, yarns, and fabrics sized with soy protein showed a considerably better improvement in strength and abrasion resistance compared to commercially available PVA-based size. Soy protein size had a 5-day biochemical oxygen demand /chemical oxygen demand ratio of 0.57 compared to 0.01 for PVA indicating that soy protein sizes were easily biodegradable in activated sludge. The total and ammonia nitrogen released from the proteins also did not adversely impact the biodegradability. Good sizing performance and easy biodegradability demonstrate that soy protein-based sizes have potential to replace PVA-based sizes leading to substantial benefits to the textile industry and the environment. PMID:23536274

Chen, Lihong; Reddy, Narendra; Yang, Yiqi

2013-09-01

445

Fabrication and properties of irradiation-cross-linked poly(vinyl alcohol)/clay aerogel composites.  

PubMed

Poly(vinyl alcohol) (PVOH)/clay aerogel composites were fabricated by an environmentally friendly freeze-drying of the aqueous precursor suspensions, followed by cross-linking induced by gamma irradiation without chemical additives. The influences of cross-linking conditions, i.e., absorbed dose and polymer loading as well as density on the aerogel structure and properties, were investigated. The absorbed dose of 30 kGy was found to be the optimum dose for fabricating strong PVOH composites; the compressive modulus of an aerogel prepared from an aqueous suspension containing 2 wt % PVOH/8 wt % clay increased 10-fold, and that containing 1 wt % PVOH/9 wt % clay increased 12 times upon cross-linking with a dose of 30 kGy. Increasing the solids concentration led to an increase in the mechanical strength, in accordance with the changes in microstructure from layered structure to network structure. The increase of absorbed dose also led to decreased porous size of the network structure. Cross-linking and the increase of the PVOH lead to decreased thermal stability. The strengthened PVOH/clay aerogels possess very low flammability, as measured by cone calorimetry, with heat, smoke, and volatile products release value decreasing as increasing clay content. The mechanism of flame retardation in these materials was investigated with weight loss, FTIR, WAXD, and SEM of the burned residues. The proposed mechanism is that with decreasing fuel content (increasing clay content), increased heat and mass transport barriers are developed; simultaneously low levels of thermal conductivity are maintained during the burning. PMID:25164075

Chen, Hong-Bing; Liu, Bo; Huang, Wei; Wang, Jun-Sheng; Zeng, Guang; Wu, Wen-Hao; Schiraldi, David A

2014-09-24

446

Performance optimization of coagulation/flocculation in the treatment of wastewater from a polyvinyl chloride plant.  

PubMed

This paper presents results of an experimental study of coagulation/flocculation process of wastewater generated from a polyvinyl chloride (PVC) plant. The wastewater contains fine chlorine-based solid materials (i.e. latex). Experiments were carried out using a model wastewater which is chemically identical to the actual plant but is more consistent. Inorganic ions (Al2(SO4)3, FeCl3 and CaCl2) and a water soluble commercial polyelectrolyte (PE) were added to the wastewater sample. Coagulation efficiency was determined by measuring both the turbidity of the supernatants and the relative settlement of the flocs in the jar test. It was found that aluminum and ferric ions were more efficient than calcium ions as coagulants. The addition of polyelectrolyte was found to improve substantially the coagulation/flocculation process. It was found that the (Al2(SO4)3) combined with the polyelectrolyte at certain pH and agitation speed gave the best results compared to calcium chloride or ferric chloride when combined with the same concentration of polyelectrolyte. Only 0.0375g of a solution of (0.5% Al2(SO4)3) was required to coagulate the model wastewater. Ferric chloride (2.5% FeCl3) combined with the polyelectrolyte, on the other hand, required 0.1g while the optimum turbidity is almost the same. As for calcium chloride (2.5% CaCl2) it was found to be the least effective. The coagulation/flocculation process was found to be dependent on both pH and the agitation speed. PMID:18471966

Almubaddal, F; Alrumaihi, K; Ajbar, A

2009-01-15

447

Separation of polyvinyl chloride (PVC) from automobile shredder residue (ASR) by froth flotation with ozonation.  

PubMed

The purpose of this study is to develop froth flotation to separate polyvinyl chloride (PVC) from automobile shredder residue (ASR) plastic mixtures of variable composition. Some polymers in ASR polymer mixtures have similar density and hydrophobicity with PVC and thus selective flotation of PVC from ASR polymer mixtures cannot be achieved. The present study focused on the surface modification of PVC with ozonation, and then the modified PVC can be separated from other polymers by the following froth flotation. The results of this study indicate that the selective recovery of PVC from real ASR polyethylene tetra pethelate (PET), polymethyl methacrylate (PMMA), polybutyl methacralate (PBMA), ethyl acrylate (EA), polycarbonate (PC) and rubber mixtures can be accomplished in a three-step process involving a gravity separation, ozonation and froth flotation. The rubber was removed from other heavy ASR (PVC, PET, PMMA, PBMA, EA and PC) polymers by froth flotation without mixing. It was found that ozonation process produced the desired difference in contact angle required (from 89.5 to 73.0 degrees ) for separation of PVC from other heavy ASR polymers, whereas the contact angles of other polymers was slightly decreased. The most of the load ASR, i.e. about 72.4% is floated away and 27.6% was settled down. The highest component 96.7% of PVC was recovered in the settled fraction. As a result of this research effort, the surface modification of PVC with ozonation can be efficiently useful to separate the PVC from other similar density ASR mixed polymers. PMID:17360113

Reddy, Mallampati Srinivasa; Kurose, Keisuke; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

2007-08-25

448

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

PubMed

The aim of this study was to determine the concentrations of six phthalic acid diesters (PAEs) [di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), butyl benzyl phthalate (BBP), diisononyl phthalate (DINP), di-n-octyl phthalate (DNOP), and diisodecyl phthalate (DIDP)], two non-phthalic plasticizers [di(2-ethylhexyl) adipate (DEHA), 2,2,4-trimethyl-1,3-pentanediol diisobutylate (TMPDIB)], and mono 2-ethylhexyl phthalate(MEHP) in polyvinyl chloride (PVC) household products that children often places in their mouths and/or contact with their skin (41 products, 47 samples) in Japan. The detection frequencies of the studied compounds were as follows: DEHP (79 %), DINP-2 (13 %), DINP-1 (11 %), DBP (8.5 %), DEHA (8.5 %), DIDP (4.3 %), and DNOP (2.1 %). Concentrations of these compounds ranged from 0.021 % to 48 %. BBP and TMPDIB were not detected in the all samples. Most samples contained DEHP and DINP at high concentrations over 0.1 %. High concentrations of PAEs were detected in PVC household products that appear appealing to children and can possibly be licked and chewed by them. Di(2-ethylhexyl) terephtalete, diisononyl 1,2-cyclohexanedicarboxylic acid, acetyl tributyl citrate, and di(2-ethylhexyl) 4-cyclohexene-1,2-dicarboxylate used as substitute plasticizers were also detected in several samples. MEHP was present in 70 % of the samples, with concentrations ranging from trace amounts to 140 ?g/g. The ratios of MEHP against DEHP were 6.2 × 10(-4) to 1.6 × 10(-1) %. MEHP in the household products investigated in this study was most probably an impurity in DEHP. The high concentrations of PAEs detected in products that children often place in their mouth reveal the importance of replacing plasticizers in common household products, and not just children's toys, with safer alternatives. PMID:21714626

Kawakami, Tsuyoshi; Isama, Kazuo; Matsuoka, Atsuko

2011-01-01

449

Cu(II) acetate- and Mn(III) acetate-mediated radical reactions of [60]fullerene with ketonic compounds.  

PubMed

The copper(II) acetate monohydrate- or manganese(III) acetate dihydrate-mediated reaction of [60]fullerene with beta-keto esters 1a-1c or with beta-diketones 1d,1e in the presence of 4-dimethylaminopyridine afforded only dihydrofuran-fused C60 derivatives 2a-2e. However, aromatic methyl ketones 3a-3c gave two kinds of products: methanofullerenes 4a-4c and dihydrofuran-fused C60 derivatives 5a,5b. Possible reaction mechanisms are proposed. PMID:15731864

Wang, Guan-Wu; Li, Fa-Bao

2005-03-01

450

Low-Voltage Organic Thin-Film Transistors Using a Hybrid Gate Dielectric Consisting of Aluminum Oxide and Poly(vinyl phenol)  

NASA Astrophysics Data System (ADS)

This study presents low-voltage organic thin-film transistors (OTFT) using a hybrid gate dielectric consisting of aluminum oxide and poly(vinyl phenol). Aluminum oxide with a thickness of 5 nm is directly formed on an aluminum gate electrode by an oxygen plasma process. The poly(vinyl phenol) film with a thickness of 10 nm is deposited on the aluminum oxide by a spin coating process. The proposed OTFTs are able to operate at low voltages lower than 5 V because of the thin gate dielectric. The surface of the hybrid gate dielectric is finished with a hydrophobic poly(vinyl phenol) so that a pentacene semiconductor, which is deposited on the gate dielectric, produces a high quality channel, resulting in a high mobility with 0.63 cm2 V-1 s-1. Additionally, the poly(vinyl phenol) layer reduces the leakage current through the gate dielectric, generating a low off-state current of 0.02 pA/µm and thus a high on/off current ratio of 4.4×105. Finally, the pin-hole free poly(vinyl phenol) layer protects the thin aluminum oxide gate dielectric from being penetrated by source and drain electrodes; thus, an OTFT with a bottom contact structure is achieved with short channel length.

Kim, Kang Dae; Song, Chung Kun

2010-11-01

451

Growth and Methanogenesis by Methanosarcina Strain 227 on Acetate and Methanol  

PubMed Central

Methanosarcina strain 227 exhibited exponential growth on sodium acetate in the absence of added H2. Under these conditions, rates of methanogenesis were limited by concentrations of acetate below 0.05 M. One mole of methane was formed per mole of acetate consumed. Additional evidence from radioactive labeling studies indicated that sufficient energy for growth was obtained by the decarboxylation of acetate. Diauxic growth and sequential methanogenesis from methanol followed by acetate occurred in the presence of mixtures of methanol and acetate. Detailed studies showed that methanol-grown cells did not metabolize acetate in the presence of methanol, although acetate-grown cells did metabolize methanol and acetate simultaneously before shifting to methanol. Acetate catabolism appeared to be regulated in response to the presence of better metabolizable substrates such as methanol or H2-CO2 by a mechanism resembling catabolite repression. Inhibition of methanogenesis from acetate by 2-bromoethanesulfonate, an analog of coenzyme M, was reversed by addition of coenzyme M. Labeling studies also showed that methanol may lie on the acetate pathway. These results suggested that methanogenesis from acetate, methanol, and H2-CO2 may have some steps in common, as originally proposed by Barker. Studies with various inhibitors, together with molar growth yield data, suggest a role for electron transport mechanisms in energy metabolism during methanogenesis from methanol, acetate, and H2-CO2. PMID:216307

Smith, Michael R.; Mah, Robert A.

1978-01-01

452

Continuum of Mechanisms for Nucleophilic Substitutions of Cyclic Acetals  

PubMed Central

The effect of nucleophile strength on diastereoselectivity in the nucleophilic substitution of cyclic acetals was explored. Stereoselectivity remained constant and high as nucleophilicity increased until a threshold value was reached. Beyond this point, however, selection of Lewis acid determined whether stereochemical inversion or erosion was observed. PMID:18844363

Krumper, Jennifer R.; Salamant, Walter A.; Woerpel, K. A.

2009-01-01

453

Synthesis of methyl acetate from syngas via dimethyl ether  

SciTech Connect

Dimethyl ether (DME) can be used as a building block for a variety of specialty chemicals in the petrochemical industry. Its utilization stems mainly from its efficient production from synthesis gas in a single stage. This Liquid Phase Dimethyl Ether (LP-DME) process, based on dual catalysts slurried in inert oil, can alleviate the chemical equilibrium limitation governing the methanol synthesis reaction and concurrently improve once-through syngas conversion and reactor productivity. Studies in the past have focused on using DME as a feedstock for gasoline range hydrocarbons as well as lower olefins. The focus of this investigation is to study the synthesis of methyl acetate, an important intermediate for acetic acid, from dimethyl ether. In particular, conversion of DME to methyl acetate is investigated over a variety of Group VIII metal substituted phosphotungstic acid salts. Key aspects of the process such as the effect of active metal, support types, multiple metal loading, and feed conditions are examined. Thus, this paper introduces a novel process route for synthesis of methyl acetate from natural gas-based syngas via dimethyl ether as an intermediate.

Tartamella, T.; Sardesai, A.; Lanterman, H.B.; Lee, S.

1999-07-01

454

Synthesis of vinyl acetate on palladium-based catalysts  

E-print Network

Vinyl acetate (VA) is an important monomer used in the production of paints, surface coatings and adhesives. Synthesis of VA is usually carried out over supported Pd alloy catalysts with a selectivity as high as 96% and described as C2H4 + CH3COOH...

Kumar, Dheeraj

2009-06-02

455

Urinary Phenyl Acetate: A Diagnostic Test for Depression?  

Microsoft Academic Search

The compound 2-phenylethylamine is an ``endogenous amphetamine'' which may modulate central adrenergic functions. 2-Phenylethylamine is mainly metabolized by monoamine oxidase to form phenyl acetate (PAA). The 24-hour urinary excretion of PAA was measured in normal healthy volunteers and depressed patients. Patients were diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, edition 3. In 70 percent of healthy

H. C. Sabelli; J. Fawcett; F. Gusovsky; J. Javaid; J. Edwards; H. Jeffriess

1983-01-01

456

Hydrogen bonding of hydrates of double acetic acid molecules.  

PubMed

In the chemical industry, the separation of the acetic acid from the HAc/H(2)O system is always influenced by the hydrogen bonding. In the present work, an investigation on the hydrogen bonding of various hydrates of double acetic acid (HAc) molecules is carried out with two first-principle methods including ab initio molecular dynamics (AIMD) simulation and quantum chemical calculations (QCC). From the AIMD simulation, the distribution of the head-on rings of acetic acid is revealed and shows that the favorable structures tend to be the acetic acid hydrates rather than the HAc cyclic dimer. The 6- and 10-membered head-on rings involving single and double HAc molecules, respectively, appear to be the dominant structures. According to the QCC, the most stable structure is found to be the conformer with the biggest head-on ring in each group. The energetics of the rings indicates that the stability of the ring increases with increased ring size (with the exception of the 9-membered ring), and the 10-membered ring is the most stable. The relative stability of the ring structures implied by the static QCC result is in good agreement with the statistical ring distribution of the AIMD simulation. PMID:19462952

Pu, Liang; Sun, Yueming; Zhang, Zhibing

2009-06-18

457

THERMOREGULATION IN MICE FOLLOWING ACUTE ADMINISTRATION OF LEAD ACETATE  

EPA Science Inventory

Several reports in the literature suggest a relationship between lead intoxication and thermoregulatory capacity. To investigate the effects of lead on the control of body temperature, mice of the BALB/c strain were injected intraperitoneally with lead acetate (0 to 100 mg/kg) wh...

458

Asymmetric Hydrogenation of Itaconic Acid and Enol Acetate Derivatives with  

E-print Network

. A variety of chiral 2-substituted succinic acids and chiral acetates have been obtained in excellent ee efficient synthesis of chiral R-amino acids via transition metal-catalyzed asymmetric hydrogenation has become one of most efficient methods for the synthesis of chiral R-amino acids, chiral -amino

Zhang, Xumu

459

Superacidic low-temperature cyclization of terpenols and their acetates  

Microsoft Academic Search

The superacidic low-temperature cyclization of terpenols and their acetates by fluorosulfonic acid represents a highly efficient chemo- and structurally selective and stereospecific process. Homoallylic alcohols (a-isomers of cycloterpenols) are the products of cyclization of terpenols; the configuration of the hydroxymethyl group in the products is predetermined by the configuration of the allylic double bond in aliphatic or partially cyclized precursors.

P. F. Vlad; N. D. Ungur; Nguen Hung; V. B. Perutsky

1995-01-01

460

Electronic interactions between gold films and mn12-acetate  

E-print Network

the presence of a surface layer of Mn12–acetate, have been performed using a dilution refrigerator. Quantitative fits to the data using the predictions of weak localization theory were performed using a least-squares fit method in order to determine...

Means, Joel Lewis

2009-05-15