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1

Preparation of poly(vinyl formal) of high acetalization  

Microsoft Academic Search

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

P. Chetri; N. N. Dass

1997-01-01

2

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

Microsoft Academic Search

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

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

2010-01-01

3

A novel simple one-step air jet spinning approach for deposition of poly(vinyl acetate)/hydroxyapatite composite nanofibers on Ti implants.  

PubMed

A biocompatible coating consists of a poly(vinyl acetate)/hydroxyapatite (PVAc/HA) composite nanofiber mat was applied to NaOH-treated titanium metal by means of a novel, facile and efficient air jet spinning (AJS) approach. Results showed that HA nanoparticles (NPs) strongly embedded onto the AJS single fiber surface resulting in a strong chemical interfacial bonding between the two phases due to the difference in kinetic energies. It was proven that AJS membrane coatings can provide significant improvement in the corrosion resistance of titanium substrate. Interestingly, the biocompatibility using MC3T3-E1 osteoblast to the PVAc/HA fiber composite layer coated on Ti was significantly higher than pure titanium-substrates. PMID:25686997

Abdal-Hay, Abdalla; Hamdy, Abdel Salam; Khalil, Khalil Abdelrazek; Lim, Ju Hyun

2015-04-01

4

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

5

Thermal stability and viscoelastic properties of MF\\/PVAc hybrid resins on the adhesion for engineered flooring in under heating system; ONDOL  

Microsoft Academic Search

The thermal properties of blends of melamine-formaldehyde (MF) resin and poly(vinyl acetate) (PVAc) for engineered flooring used on the Korean traditional ONDOL house floor heating system were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). The viscoelastic properties of the blends were also studied. Because MF resin is a thermosetting adhesive, the effect

Sumin Kim; Hyun-Joong Kim

2006-01-01

6

DMA analysis and wood bonding of PVAc latex reinforced with cellulose nanofibrils  

Microsoft Academic Search

Suspensions of commercial refined beech pulp (RBP) were further processed through mechanical disintegration (MD-RBP), chemical\\u000a modification (CM-RBP) and through chemical modification followed by mechanical disintegration (CM-MD-RBP). Nanocomposites\\u000a were prepared by compounding a poly(vinyl acetate) (PVAc) latex adhesive with increasing contents of the different types of\\u000a nanofibrils, and the resulting nanocomposites were analyzed by dynamic mechanical analysis (DMA). Also, the suitability

Francisco López-Suevos; Christian Eyholzer; Nico Bordeanu; Klaus Richter

2010-01-01

7

Study of Thermodynamical Properties of Polyvinyl Acetate in Tetrahydrofuran  

NASA Astrophysics Data System (ADS)

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

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

2012-10-01

8

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

E-print Network

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

Rock, Chris

9

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

NASA Astrophysics Data System (ADS)

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

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

2013-06-01

10

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

11

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

PubMed

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

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

2007-07-01

12

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

13

Preparation, characterization and release of amoxicillin from cellulose acetate and poly(vinyl pyrrolidone) coaxial electrospun fibrous membranes  

Microsoft Academic Search

Electrospinning is a method that has been used to prepare polymeric fibers, with diameters ranging from nanometers to a micrometer of polymers such as cellulose acetate (CA) and poly(vinyl pyrrolidone) (PVP), and to develop membranes with applications in microencapsulation, for controlled release of drugs and for chemical and biological sensors. This work shows the feasibility and optimal conditions for the

M. M. Castillo-Ortega; A. Nájera-Luna; D. E. Rodríguez-Félix; J. C. Encinas; F. Rodríguez-Félix; J. Romero; P. J. Herrera-Franco

2011-01-01

14

In-situ X-ray reflectivity measurement of polyvinyl acetate thin films during glass transition  

NASA Astrophysics Data System (ADS)

Thin films quite often have different properties from the bulk. In the case of polyvinyl acetate, it is known that glass transition takes place at around room temperature (~30 °C), and the thermal expansion coefficient is well determined for the bulk. However, with a ~0.1 micron thin film, such measurements are not generally easy. The present paper reports the results of in-situ X-ray reflectometry, which is extremely sensitive to slight changes in layer thickness. It was found that thickness increases from 968 to 985 Å when the temperature is scanned from 10 to 55 °C, but the slope changes from 0.22 to 0.72 Å/ °C at around 35 °C. As the thickness change is due to thermal expansion, it is possible to discuss the mechanical properties below and above the transition temperature.

Mizusawa, Mari; Sakurai, Kenji

2011-09-01

15

Pervaporation separation of water-acetic acid mixtures through poly(vinyl alcohol) membranes crosslinked with glutaraldehyde  

Microsoft Academic Search

Poly(vinyl alcohol) (PVA) membranes crosslinked with glutaraldehyde (GA) were prepared by a solution method for the pervaporation separation of acetic acid-water mixtures. In the solution method, dry PVA films were crosslinked by immersion for 2 days at 40°C in reaction solutions which contained different contents of GA, acetone and a catalyst, HCl. In order to fabricate the crosslinked PVA membranes

Choong-Kyun Yeom; Kew-Ho Lee

1996-01-01

16

Microwave irradiation induced modifications on the interfaces in SAN/EVA/PVC and PVAc/BPA/PVP ternary polymer blends: Positron lifetime study  

NASA Astrophysics Data System (ADS)

Ternary polymer blends of poly(styrene-co-acrylonitrile)/poly(ethylene-co-vinylacetate)/poly(vinyl chloride) (SAN/EVA/PVC) and poly(vinyl acetate)/bisphenol A/polyvinylpyrrolidone (PVAc/BPA/PVP) with different compositions have been prepared by solvent casting method and characterized by positron lifetime spectroscopy and differential scanning calorimetry DSC. Phase modifications have been induced by irradiating the blends with microwave radiation. These changes have been monitored by measuring the free-volume content in the blends. The results clearly show improved interactions between the constituent polymers of the blends upon microwave irradiation. However, the free-volume data and DSC measurements are found to be inadequate to reveal the changes at the interfaces and the interfaces determine the final properties of the blend. For this we have used hydrodynamic interaction (?ij) approach developed by us to measure strength of hydrodynamic interaction at the interfaces. These results show that microwave irradiation stabilizes the interfaces if the blend contains strong polar groups. SAN/EVA/PVC blend shows an increased effective hydrodynamic interaction from -3.18 to -4.85 at composition 50/35/15 upon microwave irradiation and PVAc/BPA/PVP blend shows an increased effective hydrodynamic interaction from -3.81 to -7.57 at composition 20/50/30 after irradiation.

Dinesh, Meghala; Chikkakuntappa, Ranganathaiah

2013-09-01

17

An Anthropomorphic Polyvinyl Alcohol Triple-Modality Brain Phantom based on  

E-print Network

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

Paris-Sud XI, Université de

18

Optimization of tribological and mechanical properties of nanocomposites of polyurethane/poly(vinyl acetate)/CaCO3.  

PubMed

Properties of samples containing polyurethane (PU), poly(vinyl acetate) (PVAc) and nanosize particles of calcium carbonate (CaCO3) are correlated with concentrations of these components. Interphase phenomena in PU/PVAc/CaCO3 nanohybrids have been studied before, we focus here on wear and scratch resistance. In addition to polymer blends containing CaCO3, the effects of adding CaCO3 with grafted PVAc, and CaCO3 with grafted silane and PVAc in varying ratios are also evaluated. For blends that do not contain the filler, a hypothesis explaining the concentration dependence of friction called the Bump Model is advanced and supported by the experimental results. In particular, we explain how creating a blend containing only 10% of a second polymer results in a dramatic drop of friction of the majority polymer. In single scratch testing, above 3% the filler displays 'its own' resistance to scratching. Chemical modification of the filler results in shallower residual depths--a consequence of improved interaction of the filler with the polymeric matrix. In sliding wear determination, strain hardening is seen for blends as well as for filler-containing composites. In tensile testing, addition of an unmodified filler increases the elongation at break and thus lowers the brittleness; the effect is even larger for chemically modified fillers. PMID:21780387

Brostow, Witold; Kumar, Puneet; Vrsaljko, Domagoj; Whitworth, Jenna

2011-05-01

19

Analysis of Dns-amino acids by liquid chromatography. I. Selection of optimum mobile phase composition for separation of Dns-amino acids on polyvinyl acetate gel.  

PubMed

The separation of a mixture of ten Dns-amino acids (Gns-Gly, -Ala, -Val, -Leu, -Pro, -Hypro, -Met, -Ser, -Asn and -Gln) was carried out by liquid chromatography by using macroreticular polyvinyl acetate gel as a packing material. Different mobile phase systems were investigated, based mainly on mixtures of n-hexane with ethanol, methanol, chloroform, acetone, methyl ethyl ketone, ethyl acetate, dioxane and tetrahydrofuran. The solvent composition was fixed so as to elute all of the components of the sample mixture in a practical period of 2 h. Satisfactory separation of the ten components was obtained with the n-hexane-ethanol (90:10) system. The presence of methanol as a modifier in the n-hexane was effective in reducing the elution time, but the separation was not as satisfactory. Chloroform or dioxane was useful only for the separation of Ser, Asn and Gln. Acetone, methyl ethyl ketone, ethyl acetate and tetrahydrofuran were not suitable for practical separations of Dns-amino acids. PMID:1150766

Yamabe, T; Takai, N; Nakamura, H

1975-02-12

20

Comment on ``Temperature divergence of the dynamics of a poly(vinyl acetate) glass: Dielectric vs. mechanical behaviors'' [J. Chem. Phys. 136, 154901 (2012)  

NASA Astrophysics Data System (ADS)

The temperature dependence of polymer dynamics below the standard glass transition is of considerable interest. Glassy relaxation dictates the process of physical aging, and understanding these slow dynamics helps in assessing a possible divergence at a finite temperature. In a recent paper, Zhao and McKenna have measured the equilibrium dynamics of poly(vinyl acetate) in the range from Tg - 15 K to Tg + 30 K using Struiks protocol [J. Zhao and G. B. McKenna, J. Chem. Phys. 136, 154901 (2012)]. In a figure that is meant to compare their results with dielectric relaxation data from Wagner and Richert [Polymer 38, 255 (1997)], dielectric retardation data from that work is shown instead. The corrected figure shows a considerable difference in the two measurements below Tg - 10 K, Arrhenius versus Vogel-Fulcher-Tammann behavior, and a possible source of the difference is discussed.

Richert, Ranko

2013-10-01

21

Experiments on polymer gels: Swelling and deformation of poly(vinyl acetate) networks in equilibrium with a ?-diluent  

Microsoft Academic Search

Deswelling of chemically cross-linked poly(viny1 acetate) gels swollen by isopropyl alcohol at the &emperature (I'= 52 ' C ) was induced by two independent methods: ( 1) the activity of the diluent around the stress-free gels was lowered by dissolving a polymer in the equilibrium liquid phase and (2) gels equilibrated with pure diluent were subjected to unidirectional compressive stress.

Ferenc Horkay; Miklós Zrinyi

1990-01-01

22

A case-controlled, retrospective, comparative study on the use of biodegradable synthetic polyurethane foam versus polyvinyl acetate sponge after nasal fracture reduction.  

PubMed

One of the most frequently used packing materials in closed reduction of a nasal bone fracture is the hydroxylated polyvinyl acetate sponge (PVAS; Merocel(®)); however this may cause synechia, epistaxis, and pain. Synthetic polyurethane foam (SPF; Nasopore(®) Forte) has recently been used in septoplasty to prevent synechia or restenosis and haematoma formation. The purpose of this study was to compare the effects of PVAS and SPF on postoperative appearance and discomfort following the reduction of nasal bone fractures. We retrospectively reviewed all patient questionnaires and medical histories, and clinical photographs and computed tomography scans obtained before and after surgery. Outcomes were assessed using the Global Aesthetic Improvement Scale (GAIS) score and visual analogue scale (VAS) scores, which were used to assess discomfort during the 6-month follow-up period. Postoperatively, there was no statistically significant difference in the GAIS for the two packing materials (P > 0.05). Postoperative epistaxis was observed at a significantly lower rate in the SPF group than in the PVAS group, whereas anterior rhinorrhea and posterior nasal drip occurred at significantly higher rates following removal of packing in the SPF group (P < 0.05). The results of this study suggest that synthetic dissolvable polyurethane may be a reliable alternative material for nasal packing and postoperative management following the reduction of nasal bone fractures. PMID:24613644

Jeong, H-S; Lee, H-K; Kim, H-S; Moon, M-S; Tark, K-C

2014-06-01

23

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

24

Multielectrode Pulmonary Vein Ablation Catheter (PVAC(®)): current data on results and risks.  

PubMed

Electrical isolation of pulmonary veins is the cornerstone of catheter ablation for patients with symptomatic atrial fibrillation. However, uncertainty surrounds the choice of energy source in pulmonary vein isolation (PVI). Various alternative techniques such as the Pulmonary Vein Ablation Catheter (PVAC(®), Medtronic Inc., Minneapolis, MN, USA) have been developed to facilitate PVI. This over-the-wire multielectrode catheter is delivering duty-cycled bipolar and unipolar radiofrequency (RF) energy at relatively low power.PVI with this "one-shot" PVACatheter can shorten the procedure duration and lower fluoroscopy time compared to irrigated RF. It enables mapping and ablation with the same array, but fails to show signals during RF energy delivery. The effectiveness of PVAC is comparable to other technologies in randomized studies. The overall complication rate of PVAC PVI is comparable to irrigated RF and possibly slightly higher for cryoballoon PVI. Special attention has to be paid to an effective anticoagulation throughout the ablation procedure, avoidance of embolic events and pulmonary venous stenosis.The novel catheter design of the PVAC Gold(®) array may improve safety by reducing embolic events through avoidance of electrode 1-to-10 interaction and by better tissue contact due to the 20° forward tilt. Although clinical data with this new array are lacking so far, the PVAC system has been shown to be a promising tool for PVI. However, prospective studies especially with the novel array are required to determine its true role for catheter ablation of atrial fibrillation in the future. PMID:25070931

Mönnig, Gerold; Eckardt, Lars

2014-12-01

25

An anthropomorphic polyvinyl alcohol triple-modality brain phantom based on Colin27.  

PubMed

We propose a method for the creation of an anatomically and mechanically realistic brain phantom from polyvinyl alcohol cryogel (PVA-C) for validation of image processing methods for segmentation, reconstruction, registration, and denoising. PVA-C is material widely used in medical imaging phantoms for its mechanical similarities to soft tissues. The phantom was cast in a mold designed using the left hemiphere of the Colin27 brain dataset and contains deep sulci, a complete insular region, and an anatomically accurate left ventricle. Marker spheres and inflatable catheters were also implanted to enable good registration and simulate tissue deformation, respectively. The phantom was designed for triple modality imaging, giving good contrast images in computed tomography, ultrasound, and magnetic resonance imaging. Multimodal data acquired from this phantom are made freely available to the image processing community (http://pvabrain. inria.fr) and will aid in the validation and further development of medical image processing techniques. PMID:20879303

Chen, Sean Jy-Shyang; Hellier, Pierre; Gauvrit, Jean-Yves; Marchal, Maud; Morandi, Xavier; Collins, D Louis

2010-01-01

26

Characterization of Branched Poly (vinyl Acetate) by GPC and Low Angle Laser Light Scattering Photometry  

Microsoft Academic Search

Poly (vinyl acetate), PVAC, synthesized by bulk polymerization over a range of initiator concentrations ([AIBN] = 10 to 4 × 10 g-mole\\/1), temperatures (50°C, 60°C, 70°C, and 80°C) and conversion levels (3 to > 90%) were characterized using low angle laser light scattering (LALLS) photometry to measure Mw of the whole polymers. A number of these samples were characterized using

A. E. Hamielec; A. C. Ouano; L. L. Nebenzahl

1978-01-01

27

Poly(N-vinylpyrrolidone)-block-poly(vinyl acetate) as a drug delivery vehicle for hydrophobic drugs.  

PubMed

Poly((N-vinylpyrrolidone)-block-poly(vinyl acetate)) (PVP-b-PVAc) block copolymers of varying molecular weight and hydrophobic block lengths were synthesized via controlled radical polymerization and investigated as carriers for the solubilization of highly hydrophobic riminophenazine compounds. These compounds have recently been shown to exhibit a strong activity against a variety of cancer types. PVP-b-PVAc self-assembles into polymer vesicles in aqueous media, and the dialysis method was used to load the water-insoluble drug (clofazimine) into these polymer vesicles. The polymer vesicles were characterized by 1H NMR spectroscopy to confirm vesicle formation and the incorporation of the anticancer drugs into the polymer vesicles. Dynamic light scattering was used to determine the particle size and particle size distribution of the drug-loaded vesicles as well as the stability of the vesicles under physiological conditions. The size of the polymer vesicles did not increase upon loading with clofazimine, and the particle size of 180-200 nm and the narrow particle size distribution were maintained. The morphology of the vesicles was examined by transmission electron microscopy. The polymer vesicles had a relatively high drug loading capacity of 20 wt %. In vitro cytotoxicity studies of PVP-b-PVAc and drug-loaded PVP-b-PVAc were performed against MDA-MB-231 multidrug-resistant breast epithelial cancer cells and MCF12A nontumorigenic breast epithelial cells. In vitro experiments demonstrated that the PVP-b-PVAc drug carrier showed no cytotoxicity, which confirms the biocompatibility of the PVP-b-PVAc drug carrier. The results indicate that the present PVP-b-PVAc block copolymer could be a potential candidate as a drug carrier for hydrophobic drugs. PMID:23116120

Bailly, Nathalie; Thomas, Mark; Klumperman, Bert

2012-12-10

28

Cellulose Nanocrystals/ZnO as a Bifunctional Reinforcing Nanocomposite for Poly(vinyl alcohol)/Chitosan Blend Films: Fabrication, Characterization and Properties  

PubMed Central

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

29

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

PubMed Central

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

30

Development of the S3Pvac vaccine against porcine Taenia solium cysticercosis: a historical review.  

PubMed

Herein we present a review of our research dealing with vaccination against experimental and naturally acquired porcine Taenia solium cysticercosis using Taenia crassiceps-derived antigens. Results strongly support that the different versions of S3Pvac vaccine are indeed effective against porcine T. solium cysticercosis. Immunological results related to vaccination prove that protection is at least partially mediated by specific immunity. The data also support the validity of T. crassiceps murine cysticercosis as an effective tool to identify vaccine candidates against some metacestode infections. PMID:23445359

Sciutto, Edda; Fragoso, Gladis; Hernández, Marisela; Rosas, Gabriela; Martínez, José J; Fleury, Agnès; Cervantes, Jacquelynne; Aluja, Aline; Larralde, Carlos

2013-08-01

31

Development of the S3Pvac vaccine against murine Taenia crassiceps cysticercosis: a historical review.  

PubMed

Our work of the last 25 yr was concerned with the development of a vaccine aimed to prevent porcine Taenia solium cysticercosis and was based on cross-reacting Taenia crassiceps antigens that had proved protective against experimental intraperitoneal murine T. crassiceps cysticercosis (EIMTcC). In recent times the efficacy of the vaccine has been considered in need of confirmation, and the use of EIMTcC has been questioned as a valid tool in screening for vaccine candidates among the many antigens possibly involved. A review of our work divided in 2 parts is presented at this point, the first dealing with EIMTcC and the second with porcine T. solium cysticercosis (presented in this issue). Herein, we revise our results using EIMTcC as a measure of the protective capacity of T. crassiceps complex antigen mixtures, of purified native antigens, and of S3Pvac anti-cysticercosis vaccine composed by 3 protective peptides: GK-1, KETc1, and KETc12 either synthetic or recombinantly expressed and collectively or separately, by diverse delivery systems when administered at different doses and by different routes. Statistical analyses of the data lead confidently to the strong inference that S3Pvac is indeed an effective vaccine against EIMTcC via specific and non-specific mechanisms of protection. PMID:23409920

Sciutto, Edda; Fragoso, Gladis; Hernández, Marisela; Rosas, Gabriela; Martínez, José J; Fleury, Agnès; Cervantes, Jacquelynne; Aluja, Aline; Larralde, Carlos

2013-08-01

32

Delivered by Ingenta to: University of Southern California  

E-print Network

and Mechanical Properties of Nanocomposites of Polyurethane/Poly(vinyl acetate)/CaCO3 Witold Brostow1 , Puneet polyurethane (PU), poly(vinyl acetate) (PVAc) and nanosize parti- cles of calcium carbonate (CaCO3, Filler Reinforcement, Poly(vinyl acetate), Polyurethane, Calcium Carbonate Modification. 1. INTRODUCTION

North Texas, University of

33

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

PubMed

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

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

2015-01-01

34

76 FR 13660 - Polyvinyl Alcohol From Taiwan  

Federal Register 2010, 2011, 2012, 2013, 2014

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

2011-03-14

35

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

36

Heat resistance poly(vinyl alcohol) hydrogel  

NASA Astrophysics Data System (ADS)

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

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

1995-08-01

37

Inexpensive anti-cysticercosis vaccine: S3Pvac expressed in heat inactivated M13 filamentous phage proves effective against naturally acquired Taenia solium porcine cysticercosis.  

PubMed

In search of reducing vaccine production costs', a recombinant M13 phage version of the anti-cysticercosis tripeptide vaccine (S3Pvac) was developed. The efficacy of S3Pvac-Phage vs. placebo was evaluated in a randomized trial that included 1,047 rural pigs in 16 villages of Central Mexico. Three to five months after vaccination 530 pigs were examined by tongue inspection. At 5-27 months of age, 331 pigs (197 vaccinated/134 controls) were inspected at necropsy. Vaccination reduced 70% the frequency of tongue cysticercosis and, based on necropsy, 54% of muscle-cysticercosis and by 87% the number of cysticerci. PMID:18440675

Morales, Julio; Martínez, José Juan; Manoutcharian, Karen; Hernández, Marisela; Fleury, Agnes; Gevorkian, Goar; Acero, Gonzalo; Blancas, Abel; Toledo, Andrea; Cervantes, Jacquelynne; Maza, Victor; Quet, Fabrice; Bonnabau, Henri; de Aluja, Aline S; Fragoso, Gladis; Larralde, Carlos; Sciutto, Edda

2008-06-01

38

Improvement of the synthetic tri-peptide vaccine (S3Pvac) against porcine Taenia solium cysticercosis in search of a more effective, inexpensive and manageable vaccine.  

PubMed

Vaccination of pigs may curtail Taenia solium transmission by reducing the number of cysticerci, the precursors of adult intestinal tapeworms in humans. Several antigen preparations induce protection against porcine cysticercosis in experimental settings but only one subunit vaccine (S3Pvac) has been tested and proved effective in the field against naturally acquired disease. Besides improving of the vaccine's effectiveness, significant reductions in production costs and in the logistics of its administration are necessary for the feasibility of nationwide control programs. This review highlights the development of several versions of S3Pvac aimed to increase effectiveness, reduce costs and increase feasibility by novel delivery systems and alternative routes of administration. PMID:17188784

Sciutto, Edda; Rosas, Gabriela; Hernández, Marisela; Morales, Julio; Cruz-Revilla, Carmen; Toledo, Andrea; Manoutcharian, Karen; Gevorkian, Goar; Blancas, Abel; Acero, Gonzalo; Hernández, Beatriz; Cervantes, Jacquelynne; Bobes, Raul J; Goldbaum, Fernando A; Huerta, Mirna; Diaz-Orea, Alicia; Fleury, Agnes; de Aluja, Aline S; Cabrera-Ponce, Jose Luis; Herrera-Estrella, Luis; Fragoso, Gladis; Larralde, Carlos

2007-02-01

39

Recombinant S3Pvac-phage anticysticercosis vaccine: Simultaneous protection against cysticercosis and hydatid disease in rural pigs.  

PubMed

This paper provides macroscopic and histological evidence on the statistically significant protective effects of S3Pvac-phage vaccination against porcine cysticercosis and hydatidosis. The study included 391 rustically bred pigs (187 vaccinated and 204 controls). Vaccination significantly reduced the prevalence of cysticercosis by 61.7%. Vaccination also significantly reduced by 56.1% the prevalence of hydatidosis caused by Echinococcus granulosus in pigs. The presence of the vaccine epitopes in both cestodes is probably involved in the cross-protection observed. Increased inflammation was found in 5% of cysticerci recovered from controls, versus 24% from vaccinated pigs (P<0.01). Hydatid cysts were non-inflammatory in either group. Vaccination was effective to prevent one single disease, but it failed to prevent the simultaneous infections with both parasites in a same pig. The widening of the S3Pvac-phage vaccine protective repertoire to include hydatidosis is a convenient feature that should reduce the prevalence of two frequent zoonoses that affect rustic porcine breading with a single action. Thus, the costs of two different vaccination programs would be reduced to a single one with significant reduction in both zoonoses. PMID:21251758

Morales, Julio; de Aluja, Aline S; Martínez, Jose Juan; Hernández, Marisela; Rosas, Gabriela; Villalobos, Nelly; Hernández, Beatriz; Blancas, Abel; Manoutcharian, Karen; Gevorkian, Goar; Cervantes, Jacquelynne; Díaz, Alicia; Fleury, Agnes; Fragoso, Gladis; Larralde, Carlos; Sciutto, Edda

2011-02-28

40

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

41

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2011 CFR

... 2011-04-01 2011-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670...Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact...

2011-04-01

42

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2013 CFR

... 2013-04-01 2013-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670...Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact...

2013-04-01

43

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

44

21 CFR 177.1670 - Polyvinyl alcohol film.  

Code of Federal Regulations, 2012 CFR

... 2012-04-01 2012-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670...Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact...

2012-04-01

45

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

46

Experimental study of drop-interface coalescence in the presence of polymer stabilisers  

Microsoft Academic Search

An experimental study has been carried out to characterise the performance of polymer stabilisers, partially hydrolysed polyvinyl acetate (PVAc), used in suspension polymerisation processes. The stabilisers are ranked by their ability to stabilise the dispersion characterised by the median coalescence time of a single drop with its homophase at a planar liquid\\/liquid interface. Results show that the stability of the

Yinghe He; Tony Howes; Jim D Litster; Glen H Ko

2002-01-01

47

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

48

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

Microsoft Academic Search

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

Mirzan T Razzak; Darmawan Darwis; Zainuddin; Sukirno

2001-01-01

49

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

Microsoft Academic Search

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

Hans A. Dahl; Svein Ivar Mellgren

1970-01-01

50

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

PubMed

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

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

2014-11-10

51

Further evaluation of the synthetic peptide vaccine S3Pvac against Taenia solium cysticercosis in pigs in an endemic town of Mexico.  

PubMed

Taenia solium cysticercosis is a parasitic disease frequently affecting human health and the pig industry in many developing countries. A synthetic peptide vaccine (designated S3Pvac) against porcine cysticercosis has been developed previously as an aid to interrupt transmission and has been shown to be effective. The results of the present study support the effectiveness of the vaccine under endemic field conditions. However, given the time-frame of the vaccination trial, no changes in the local levels of transmission were detectable before and after vaccination using sentinel pigs. Thus, this investigation shows the limited usefulness of single vaccination as the sole means of interrupting Taenia solium transmission in an endemic region. PMID:16948875

Sciutto, E; Morales, J; Martínez, J J; Toledo, A; Villalobos, M N; Cruz-Revilla, C; Meneses, G; Hernández, M; Díaz, A; Rodarte, L F; Acero, G; Gevorkian, G; Manoutcharian, K; Paniagua, J; Fragoso, G; Fleury, A; Larralde, R; De Aluja, A S; Larralde, C

2007-01-01

52

RESEARCH PAPER Effects of iron oxide nanoparticles on polyvinyl alcohol  

E-print Network

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

Guo, John Zhanhu

53

Radiolysis of tetrazolium salts in polyvinyl alcohol  

SciTech Connect

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

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

1992-01-01

54

Polyvinyl alcohol battery separator containing inert filler  

SciTech Connect

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

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

1981-06-01

55

Polyvinyl Alcohol Particle Size and Suspension Characteristics  

Microsoft Academic Search

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

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

56

Preparation of vinyl acetate  

DOEpatents

This invention pertains to the preparation of vinyl acetate by contacting a mixture of hydrogen and ketene with a heterogeneous catalyst containing a transition metal to produce acetaldehyde, which is then reacted with ketene in the presence of an acid catalyst to produce vinyl acetate.

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

1998-01-01

57

Electrooxidation of tigogenin acetate  

Microsoft Academic Search

Electrooxidation of tigogenin acetate afforded two products: 3?-acetoxy-16?-hydroxy-23,24-dinor-5?-cholanoic acid lactone (2) and 20-epitigogenin acetate (3). The structure of the latter compound was confirmed by an X-ray analysis. The tentative mechanism of reaction is proposed.

Jacek W. Morzycki; Yliana López; Jolanta P?oszy?ska; Rosa Santillan; Leszek Siergiejczyk; Andrzej Sobkowiak

2007-01-01

58

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

59

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

60

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-04-08

61

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2013-07-01

62

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

E-print Network

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

Trikalitis, Pantelis N.

63

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2010-07-01

64

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

NASA Astrophysics Data System (ADS)

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

Lipscomb, Corinne Elizabeth

65

Methane from acetate.  

PubMed Central

The general features are known for the pathway by which most methane is produced in nature. All acetate-utilizing methanogenic microorganisms contain CODH which catalyzes the cleavage of acetyl-CoA; however, the pathway differs from all other acetate-utilizing anaerobes in that the methyl group is reduced to methane with electrons derived from oxidation of the carbonyl group of acetyl-CoA to CO2. The current understanding of the methanogenic fermentation of acetate provides impressions of nature's novel solutions to problems of methyl transfer, electron transport, and energy conservation. The pathway is now at a level of understanding that will permit productive investigations of these and other interesting questions in the near future. PMID:1512186

Ferry, J G

1992-01-01

66

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

SciTech Connect

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

Derrick, W.E.

1989-04-18

67

Development of semicrystalline poly(vinyl alcohol) hydrogels for biomedical applications.  

PubMed

Swollen crosslinked poly(vinyl alcohol) (PVA) networks were developed and tested as potential biomaterials. They were prepared by electron-beam irradiation of aqueous PVA solutions at various temperatures and doses of irradiation. These materials were characterized by low mechanical properties and especially by low elongation at break and ultimate tensile strength. Reinforcement was achieved by a two-stage dehydration-annealing process, introducing crystallites in the polymeric network. Improved mechanical properties were achieved due to the presence of this crystalline PVA phase. Due to their structure, these hydrogels are proposed to be used as biomembranes for selective transport of macromolecules and as biomaterials for synthetic articular cartilage applications. Surface heparinization was accomplished by reacting heparin to the hydroxyl groups of the PVA surface, through covalent acetal bridges. PMID:853047

Peppas, N A; Merrill, E W

1977-05-01

68

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

NASA Astrophysics Data System (ADS)

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

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

2001-07-01

69

[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

70

Fabrication of polyvinyl alcohol coated polystyrene shells  

SciTech Connect

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

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

1987-11-01

71

Polyvinyl alcohol membranes as alkaline battery separators  

SciTech Connect

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

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

1982-01-01

72

Effect of gamma radiation on gelation in polyvinyl alcohol solutions  

NASA Astrophysics Data System (ADS)

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

Wenxiu, Chen; Huaying, Bao; Manwei, Zhang

73

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

74

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2012 CFR

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

2012-04-01

75

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2011 CFR

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

2011-04-01

76

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2013 CFR

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

2013-04-01

77

21 CFR 175.270 - Poly(vinyl fluoride) resins.  

Code of Federal Regulations, 2014 CFR

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

2014-04-01

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

Hydrothermal carbonization of poly(vinyl chloride).  

PubMed

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

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

2015-01-01

80

Piezoresistive Properties of Polyvinyl Chloride Composites  

NASA Astrophysics Data System (ADS)

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

Toprakci, Hatice Aylin Karahan

81

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

82

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

Federal Register 2010, 2011, 2012, 2013, 2014

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

2012-03-09

83

Radiation-chemical preparation of poly(vinyl alcohol) hydrogels  

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

84

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

85

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

86

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.

87

Preparation and characterization of film of poly vinyl acetate ethylene copolymer emulsion  

NASA Astrophysics Data System (ADS)

In order to improve the storage modulus and water resistance of poly (vinyl acetate), the vinyl acetate and poly (vinyl alcohol) (PVA) were respectively used as monomers and protective colloid to prepare a new kind of polyvinyl acetate emulsion adhesive by continuous emulsion polymerization. The dynamic mechanics, particle distribution, glass transition temperature, polymer emulsion structure of both polymerized and copolymerized emulsion were analyzed by SEM, DMA and XPS, respectively. The results indicated that the copolymerized emulsion has the appropriate particle size and the uniform particle distribution, the glass transition temperature increased from 50 °C to 70 °C, compared with poly (vinyl acetate). It could be seen from XPS spectra of copolymerized emulsion that key characteristic peak of Cdbnd O was still existent. X-ray photoelectron spectra revealed that the addition of EVA did not generate the new bond, whereas the maximum percentage increases in ester was determined in the composite film with the introduction of EVA of 25%, which indicated that the composite film has copolymer structure. The storage modulus and water resistance of poly (vinyl acetate) were improved due to the introduction of the EVA.

Zhang, Yanhua; Gu, Jiyou; Tan, Haiyan; Shi, Junyou; Di, Mingwei; Zuo, Yingfeng; Qiu, Si

2013-07-01

88

Molecular Structure of Sodium acetate  

NSDL National Science Digital Library

Sodium acetate is known for its ability to supercool. It freezes at 130 degrees, but can exist as a liquid at a much lower temperature. In order to melt solidified sodium acetate, however, every single crystal must liquify, otherwise the material will recrystallize. Sodium acetate has been used as a deicer for roads and runways. It is also used a component of buffer systems and in the manufacture of pharmaceuticals and heat pads. The compound is quite stable. It may act as an irritant and be harmful if inhaled or absorbed through the skin.

2002-08-26

89

Crack formation in polyvinyl chloride coatings on underground pipes  

Microsoft Academic Search

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

B. I. Borisov; CHLORIDE COATINGS

1975-01-01

90

Immobilization of enzymes in photochemically cross-linked polyvinyl alcohol  

Microsoft Academic Search

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

Thomas Uhlich; Mathias Ulbricht; Georg Tomaschewski

1996-01-01

91

Biodegradation of a polyvinyl alcohol-starch blend plastic film  

Microsoft Academic Search

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

Tomonori Ishigaki; Yasunori Kawagoshi; Michihiko Ike; Masanori Fujita

1999-01-01

92

Review of the oral toxicity of polyvinyl alcohol (PVA)  

Microsoft Academic Search

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

C. C DeMerlis; D. R Schoneker

2003-01-01

93

Vaginal Absorption of Polyvinyl Alcohol in Fischer 344 Rats  

Microsoft Academic Search

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

J. M. Sanders; H. B. Matthews

1990-01-01

94

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

Microsoft Academic Search

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

Wang Jianlong; Hou Wenhua; Qian Yicr

1995-01-01

95

Preclinical safety of anecortave acetate.  

PubMed

A number of preclinical safety pharmacology and toxicity studies have been performed on the angiostatic cortisene anecortave acetate in various species and using different routes of administration (oral, intravenous, subcutaneous, topical ocular, intraocular injection, posterior juxtascleral) and a wide range of doses (0-1,000 mg/kg). Anecortave acetate did not interact with a broad panel of pharmacological receptors and had no apparent pharmacological effects on major organ systems including the central nervous, gastrointestinal, renal, cardiovascular, and respiratory systems. Oral, topical ocular, and posterior juxtascleral administration of anecortave acetate had no significant ocular or systemic side effects or toxicity. In addition, there was no significant carcinogenic or reproductive/developmental toxicity associated with anecortave acetate in genotoxicity, carcinogenicity, and reproductive toxicity studies. PMID:17240255

Heaton, Jim; Kastner, Philip; Hackett, Robert

2007-01-01

96

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

97

Polyvinyl alcohol {gamma}-ray grafted nylon 4 membrane for pervaporation and evapomeation  

SciTech Connect

Nylon 4, which possesses high mechanical strength and good affinity for water, can be considered as a liquid separation membrane. To improve the hydrophilicity of a Nylon 4 membrane for pervaporation and evapomeation processes, and to overcome the hydrolysis of polyvinyl alcohol (PVA), this study attempts to prepare a PVA-g-Nylon 4 membrane by {gamma}-ray irradiation grafting of vinyl acetate (VAc) onto Nylon 4 membrane, followed by hydrolysis treatment. The effects of down-stream pressure, irradiation dose, VAc monomer concentration, degree of grafting, feed composition, and size of alcohols on the separation of water-alcohol mixtures were studied. The surface properties of the prepared membrane were characterized by FTIR, ESCA, and a contact angle meter. A separation factor of 13.8 and a permeation rate of 0.352 kg/m{sup 2}-h can be obtained for a PVA-g-Nylon 4 membrane with a degree of grafting of 21.2% for a 90-wt% ethanol feed concentration. Compared to the pervaporation process, the evapomeation process has a significantly increased separation factor with a decreased permeation rate for the same PVA-g-Nylon 4 membrane. 24 refs., 9 figs., 4 tabs.

Lai, J.Y.; Chen, R.Y.; Lee, K.R [Chun Yuan Univ., Chung Li (Taiwan, Province of China)

1993-05-01

98

Lactate and acetate production in Listeria innocua.  

PubMed

Listeria innocua NCTC 11289 was grown aerobically in continuous culture in defined media at 30 degrees C. Both acetate and lactate were produced, the proportion of acetate decreased with increasing dilution rate. Enzymatic analysis showed lactate dehydrogenase was activated 10-fold by fructose-1, 6-bisphosphate. The presence of phosphate acetyltransferase and acetate kinase but not pyruvate oxidase was detected, suggesting the sequential action of phosphate acetyltransferase and acetate kinase to produce acetate from acetyl CoA via acetylphosphate. PMID:8987454

Kelly, A F; Patchett, R A

1996-08-01

99

New process for producing cellulose acetate from wood in concentrated acetic acid  

Microsoft Academic Search

To explore further potential applications of acetic acid pulp, an investigation was conducted to develop a direct method for producing cellulose acetate from wood in combination with atmospheric acetic acid pulping. The process consists of delignification, totally chlorine-free bleaching, and esterification, with the concentrated acetic acid aqueous solution being used as only solvent throughout the process. The acetic acid pulp

Hironori Sato; Yasumitsu Uraki; Takao Kishimoto; Yoshihiro Sano

2003-01-01

100

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

101

Improvement in the transmission of iodine-polyvinyl alcohol polarizers  

NASA Astrophysics Data System (ADS)

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

Gunning, W. J.; Foschaar, J.

1983-10-01

102

Investigation of the alumina properties with adsorbed polyvinyl alcohol  

Microsoft Academic Search

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

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

2011-01-01

103

Kinetics of thermal degradation of poly(vinyl chloride)  

Microsoft Academic Search

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

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

104

Effect of inorganic salts on the crystallinity of polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

105

Hybrid material polyvinyl alcohol-stannic acid/stannic oxide  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

106

Surface acoustic wave humidity sensor using polyvinyl-alcohol film  

Microsoft Academic Search

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

M. Penza; V. I. Anisimkin

1999-01-01

107

Heterogeneous photocatalytic oxidation of polyvinyl alcohol in water  

Microsoft Academic Search

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

Yingxu Chen; Zhenshi Sun; Ye Yang; Qiang Ke

2001-01-01

108

Chromate reduction by Microbacterium liquefaciens immobilised in polyvinyl alcohol  

Microsoft Academic Search

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

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

2001-01-01

109

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

SciTech Connect

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

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

2008-01-01

110

Acetate fuels the cancer engine.  

PubMed

Cancer cells have distinctive nutrient demands to fuel growth and proliferation, including the disproportionate use of glucose, glutamine, and fatty acids. Comerford et al. and Mashimo et al. now demonstrate that several types of cancer are avid consumers of acetate, which facilitates macromolecular biosynthesis and histone modification. PMID:25525870

Lyssiotis, Costas A; Cantley, Lewis C

2014-12-18

111

Desmopressin Acetate in Intracranial Haemorrhage  

PubMed Central

Introduction. The secondary increase in the size of intracranial haematomas as a result of spontaneous haemorrhage or trauma is of particular relevance in the event of prior intake of platelet aggregation inhibitors. We describe the effect of desmopressin acetate as a means of temporarily stabilising the platelet function. Patients and Methods. The platelet function was analysed in 10 patients who had received single (N = 4) or multiple (N = 6) doses of acetylsalicylic acid and 3 patients (control group) who had not taken acetylsalicylic acid. All subjects had suffered intracranial haemorrhage. Analysis was performed before, half an hour and three hours after administration of desmopressin acetate. Statistical analysis was performed by applying a level of significance of P ? 0.05. Results. (1) Platelet function returned to normal 30 minutes after administration of desmopressin acetate. (2) The platelet function worsened again after three hours. (3) There were no complications related to electrolytes or fluid balance. Conclusion. Desmopressin acetate can stabilise the platelet function in neurosurgical patients who have received acetylsalicylic acid prior to surgery without causing transfusion-related side effects or a loss of time. The effect is, however, limited and influenced by the frequency of drug intake. Further controls are needed in neurosurgical patients. PMID:25610644

Kapapa, Thomas; Röhrer, Stefan; Struve, Sabine; Petscher, Matthias; König, Ralph; Wirtz, Christian Rainer; Woischneck, Dieter

2014-01-01

112

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

113

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

E-print Network

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

Singh, Jayant K.

114

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2012 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2012-04-01

115

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2014 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2014-04-01

116

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2013 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2013-04-01

117

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2011 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2011-04-01

118

21 CFR 73.2396 - Lead acetate.  

Code of Federal Regulations, 2010 CFR

...ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2396 Lead acetate. (a...additive lead acetate may be safely used in cosmetics intended for coloring hair on the scalp...The amount of the lead acetate in the cosmetic shall be such that the lead...

2010-04-01

119

Acetate kinase activity in mycoplasmas.  

PubMed

Acetate kinase activity was assayed in 13 mycoplasmas. Nine species exhibited the enzymic activity in the direction of either synthesis of acetylphosphate or adenosine triphosphate. On the other hand Mycoplasma orale, Mycoplasma arthritidis, Ureaplasma urealyticum (10 serotypes), and two strains of Anaeroplasma species exhibited only minimal levels of the enzymic activity. In these four species, the enzyme does not seem to play a key role in adenosine triphosphate formation. PMID:6263869

Muhlrad, A; Peleg, I; Robertson, J A; Robinson, I M; Kahane, I

1981-07-01

120

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

121

Features of IR Holograms recorded on Polyvinyl alcohol films  

SciTech Connect

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

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

1986-01-01

122

Starch-polyvinyl alcohol cast film-performance and biodegradation  

SciTech Connect

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

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

1996-10-01

123

Nanodielectric system for cryogenic applications: Barium titanate filled polyvinyl alcohol  

SciTech Connect

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

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

2008-01-01

124

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

125

Sodium deoxycholate functionalized graphene and its composites with polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

126

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

E-print Network

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

Khan, Saad A.

127

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

Microsoft Academic Search

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

Zhongping Chen; Hiroyuki Takei; Aaron Lewis; Isaiah Nebenzahl

1991-01-01

128

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

Microsoft Academic Search

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

George S. Davidson; Karel G. Terbrugge

129

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

130

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

131

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

Microsoft Academic Search

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

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

2010-01-01

132

Hydrolytic Stability Of Polyvinyl Alcohol (PVA) Iodine Polarizers  

NASA Astrophysics Data System (ADS)

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

Bolt, Larry

1982-05-01

133

Cross-linked polyvinyl alcohol and method of making same  

SciTech Connect

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

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

1981-06-09

134

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

135

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

136

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

137

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

138

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; Laidmäe, Ivo; Lust, Andres; Kirsimäe, Kalle

2014-01-01

139

Structural insights into enzymatic degradation of oxidized polyvinyl alcohol.  

PubMed

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

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

2014-09-01

140

Surface Sulfonation of Polyvinyl Chloride by Plasma for Antithrombogenicity  

NASA Astrophysics Data System (ADS)

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

Liu, Peng; Chen, Yashao

2004-06-01

141

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

142

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

143

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

144

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

PubMed

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

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

2002-03-15

145

[Test method for 6 phthalates in polyvinyl chloride].  

PubMed

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

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

2011-01-01

146

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

NASA Astrophysics Data System (ADS)

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

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

147

Structural changes in chlorine implanted poly(vinyl alcohol) films  

NASA Astrophysics Data System (ADS)

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

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

2007-08-01

148

Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets  

SciTech Connect

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

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

1985-05-01

149

Silver Nanoparticle Fabrication by Laser Ablation in Polyvinyl Alcohol Solutions  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

150

Cross-linked polyvinyl alcohol films as alkaline battery separators  

SciTech Connect

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

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

1983-02-01

151

Biodegradable thermoplastic composites based on polyvinyl alcohol and algae.  

PubMed

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

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

2008-03-01

152

Growth characteristics of selected fungi on polyvinyl film  

SciTech Connect

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

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

1986-04-01

153

Growth characteristics of selected fungi on polyvinyl chloride film.  

PubMed

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

Roberts, W T; Davidson, P M

1986-04-01

154

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

155

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

156

Extractive fermentation of acetic acid  

SciTech Connect

In this technoeconomic evaluation of the manufacture of acetic acid by fermentation, the use of the bacterium: Acetobacter suboxydans from the old vinegar process was compared with expected performance of the newer Clostridium thermoaceticum bacterium. Both systems were projected to operate as immobilized cells in a continuous, fluidized bed bioreactor, using solvent extraction to recover the product. Acetobacter metabolizes ethanol aerobically to produce acid at 100 g/L in a low pH medium. This ensures that the product is in the form of a concentrated extractable free acid, rather than as an unextractable salt. Unfortunately, yields from glucose by way of the ethanol fermentation are poor, but near the biological limits of the organisms involved. Conversely, C. thermoaceticum is a thermophilic anaerobe that operates at high fermentation rates on glucose at neutral pH to produce acetate salts directly in substantially quantitative yields. However, it is severely inhibited by product, which restricts concentration to a dilute 20 g/L. An improved Acetobacter system operating with recycled cells at 50 g/L appears capable of producing acid at $0.38/lb, as compared with a $0.29/lb price for synthetic acid. However, this system has only a limited margin for process improvement. The present Clostridium system cannot compete, since the required selling price would be $0.42/lb. However, if the organism could be adapted to tolerate higher product concentrations at acid pH, selling price could be reduced to $0.22/lb, or about 80% of the price of synthetic acid.

Busche, R.M. [Bio En-Gene-Er Associates, Inc., Wilmington, DE (United States)

1991-12-31

157

Nb Doping Effects on Structures and Properties of PZT Thick Films Prepared by Polymer-Assisted MOD Process  

Microsoft Academic Search

Undoped and Nb doped PZT thick films according to the formula Pb1 ? x\\/2[(Zr0.52Ti0.48)1 ? xNbx]O3 (x = 0, 0.02, 0.04, 0.06) with thickness of 1–5 ? m have been prepared by polymer poly(vinyl acetate) (PVAc)-assisted metal-organic thermal decomposition (MOD) process. Nb is introduced in the PZT thick films as a donor dopant to improve the electrical properties of PZT

Zheng Wang; Wei Ren; Jianbao Ren; Xiaoqing Wu; Peng Shi; Xiaofeng Chen; Xi Yao

2009-01-01

158

21 CFR 184.1005 - Acetic acid.  

Code of Federal Regulations, 2011 CFR

...as GRAS § 184.1005 Acetic acid. (a) Acetic acid (C2 H4 O2 , CAS Reg. No. 64-19-7) is known as ethanoic acid. It occurs naturally in plant...fermentation of carbohydrates or by organic synthesis. The principal...

2011-04-01

159

Chapter 5 Development of Adiabatic Force Field for Polyvinyl Chloride PVC  

E-print Network

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

Goddard III, William A.

160

Spectroscopic investigation of the thermal conversion of catalytically dehydrated polyvinyl alcohol  

SciTech Connect

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

Gavrilov, M.Z.

1986-09-01

161

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

162

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

SciTech Connect

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

Haskin, D.H.; Shu, P.

1990-07-10

163

Contribution of dialysate acetate to energy metabolism: Metabolic implications  

Microsoft Academic Search

Contribution of dialysate acetate to energy metabolism: Metabolic implications. During hemodialysis large amounts of acetate enter the bloodstream. Generally, it is assumed that this exogenous acetate load is oxidized immediately to carbon dioxide and water; however, the rate of plasma acetate oxidation and the effect of acetate oxidation on energy metabolism during hemodialysis has not been determined previously. The rates

Charles L Skutches; Miles H Sigler; Brendan P Teehan; Joseph H Cooper; George A Reichard

1983-01-01

164

Desvenlafaxinium chloranilate ethyl acetate solvate  

PubMed Central

In the cation of the title compound, C16H26NO2 +·C6HCl2O4 ?·C4H8O2, the 1-hy­droxy-cyclo­hexyl ring adopts a slightly distorted chair conformation. The dihedral angle between the mean planes of the 1-hy­droxy­cyclo­hexyl and 4-hy­droxy­phenyl rings is 84.0?(8)°. In the anion, the hydroxyl H atom is twisted slightly out of the ring plane with a C—C—O—H torsion angle of ?171.9°. Disorder was modeled for the methyl group of the acetate group in the solvate with an occupancy ratio of 0.583?(15): 0.417?(15). In the crystal, O—H?O hydrogen bonds are observed between cations and between cations and anions, while bifuricated N—H?(O,O) cation–anion hydrogen bonds are also present, forming chains along [010] and [100]. In addition weak cation–anion and cation–solvate C—H?O inter­actions occur. PMID:24098238

Kaur, Manpreet; Jasinski, Jerry P.; Butcher, Ray J.; Yathirajan, H. S.; Byrappa, K.

2013-01-01

165

Application of lipase immobilized on the biocompatible ternary blend polymer matrix for synthesis of citronellyl acetate in non-aqueous media: kinetic modelling study.  

PubMed

This work reports the use of new support for immobilization of lipase Burkholderia cepacia (BCL) matrix made up of polylactic acid (PLA), chitosan (CH), and polyvinyl alcohol (PVA). Initially lipase from various microbial sources and immobilization support composition was screened to obtain a robust biocatalyst. Among various biocatalysts preparation, the PLA:PVA:CH:BCL (1:6:1:2) was worked as a robust biocatalyst for the citronellyl acetate synthesis. Various reaction parameters were studied in detail to obtain the suitable reaction conditions for model citronellyl acetate synthesis reaction. Various kinetic parameters such as r(max), K(i(citronellol)), K(m(citronellol)), K(m(vinyl acetate)) were determined using non-linear regression analysis for the ternary complex as well as bi-bi ping-pong mechanism. The experimental results and kinetic study showed that citronellyl acetate synthesis catalyzed by immobilized lipase BCL followed the ternary complex mechanism with inhibition by alcohol (citronellol). The energy of activation for citronellyl acetate synthesis was found to be lower for immobilized lipase (8.9 kcal/mol) than aggregated lipase (14.8 kcal/mol) enzyme. The developed biocatalyst showed four to fivefold higher catalytic activity and excellent recyclability (up to six cycles) than the aggregated lipase. PMID:24629263

Badgujar, Kirtikumar C; Bhanage, Bhalchandra M

2014-04-10

166

21 CFR 522.2478 - Trenbolone acetate and estradiol benzoate.  

Code of Federal Regulations, 2010 CFR

...false Trenbolone acetate and estradiol benzoate. 522.2478 Section 522.2478...2478 Trenbolone acetate and estradiol benzoate. (a) Specifications . Each implant...trenbolone acetate and 3.5 mg estradiol benzoate. (2) 4 pellets, each pellet...

2010-04-01

167

Polyvinyl alcohol functionalized cobalt ferrite nanoparticles for biomedical applications  

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

168

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

PubMed

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

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

2014-05-14

169

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

PubMed

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

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

2008-04-17

170

Disruption of the acetate kinase (ack) gene of Clostridium acetobutylicum results in delayed acetate production.  

PubMed

In microorganisms, the enzyme acetate kinase (AK) catalyses the formation of ATP from ADP by de-phosphorylation of acetyl phosphate into acetic acid. A mutant strain of Clostridium acetobutylicum lacking acetate kinase activity is expected to have reduced acetate and acetone production compared to the wild type. In this work, a C. acetobutylicum mutant strain with a selectively disrupted ack gene, encoding AK, was constructed and genetically and physiologically characterized. The ack (-) strain showed a reduction in acetate kinase activity of more than 97% compared to the wild type. The fermentation profiles of the ack (-) and wild-type strain were compared using two different fermentation media, CGM and CM1. The latter contains acetate and has a higher iron and magnesium content than CGM. In general, fermentations by the mutant strain showed a clear shift in the timing of peak acetate production relative to butyrate and had increased acid uptake after the onset of solvent formation. Specifically, in acetate containing CM1 medium, acetate production was reduced by more than 80% compared to the wild type under the same conditions, but both strains produced similar final amounts of solvents. Fermentations in CGM showed similar peak acetate and butyrate levels, but increased acetoin (60%), ethanol (63%) and butanol (16%) production and reduced lactate (-50%) formation by the mutant compared to the wild type. These findings are in agreement with the proposed regulatory function of butyryl phosphate as opposed to acetyl phosphate in the metabolic switch of solventogenic clostridia. PMID:22249720

Kuit, Wouter; Minton, Nigel P; López-Contreras, Ana M; Eggink, Gerrit

2012-05-01

171

Acetate Causes Alcohol Hangover Headache in Rats  

PubMed Central

Background The mechanism of veisalgia cephalgia or hangover headache is unknown. Despite a lack of mechanistic studies, there are a number of theories positing congeners, dehydration, or the ethanol metabolite acetaldehyde as causes of hangover headache. Methods We used a chronic headache model to examine how pure ethanol produces increased sensitivity for nociceptive behaviors in normally hydrated rats. Results Ethanol initially decreased sensitivity to mechanical stimuli on the face (analgesia), followed 4 to 6 hours later by inflammatory pain. Inhibiting alcohol dehydrogenase extended the analgesia whereas inhibiting aldehyde dehydrogenase decreased analgesia. Neither treatment had nociceptive effects. Direct administration of acetate increased nociceptive behaviors suggesting that acetate, not acetaldehyde, accumulation results in hangover-like hypersensitivity in our model. Since adenosine accumulation is a result of acetate formation, we administered an adenosine antagonist that blocked hypersensitivity. Discussion Our study shows that acetate contributes to hangover headache. These findings provide insight into the mechanism of hangover headache and the mechanism of headache induction. PMID:21209842

Maxwell, Christina R.; Spangenberg, Rebecca Jay; Hoek, Jan B.; Silberstein, Stephen D.; Oshinsky, Michael L.

2010-01-01

172

Dioxouranium (VI) complexes with cellulose acetate  

Microsoft Academic Search

Dioxouranium [UO2(VI)] complexes with three degrees of substitution of cellulose acetate, prepared from viscose pulp (DS = 2.2, 2.45 and 2.86), have been synthesis and characterized. Degree of substitution (DS) is defined as the average number of CH groups substituted on each anhydrocellulose repeat unit. Probable structures of the cellulose acetate complexes were inferred from the elemental analysis data, conductance

Altaf H. Basta; Wafaa M. Hosny

1998-01-01

173

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

PubMed

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

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

2015-02-01

174

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

175

Acetate Transport and Utilization in the Rat Brain  

PubMed Central

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 (CMRace) 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 ( KMutil=0.01±0.14mM) was much smaller than for acetate transport through the blood-brain barrier ( KMt=4.18±0.83mM). The maximum transport capacity of acetate through the blood-brain barrier ( Vmaxt=0.96±0.18?mol/g/min) was nearly two-fold higher than the maximum rate of brain acetate utilization ( Vmaxutil=0.50±0.08?mol/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 blood-brain barrier, 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

2009-01-01

176

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

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

177

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.

178

Acetic acid production from food wastes using yeast and acetic acid bacteria micro-aerobic fermentation.  

PubMed

In this study, yeast and acetic acid bacteria strains were adopted to enhance the ethanol-type fermentation resulting to a volatile fatty acids yield of 30.22 g/L, and improve acetic acid production to 25.88 g/L, with food wastes as substrate. In contrast, only 12.81 g/L acetic acid can be obtained in the absence of strains. The parameters such as pH, oxidation reduction potential and volatile fatty acids were tested and the microbial diversity of different strains and activity of hydrolytic ferment were investigated to reveal the mechanism. The optimum pH and oxidation reduction potential for the acetic acid production were determined to be at 3.0-3.5 and -500 mV, respectively. Yeast can convert organic matters into ethanol, which is used by acetic acid bacteria to convert the organic wastes into acetic acid. The acetic acid thus obtained from food wastes micro-aerobic fermentation liquid could be extracted by distillation to get high-pure acetic acid. PMID:25416587

Li, Yang; He, Dongwei; Niu, Dongjie; Zhao, Youcai

2014-11-22

179

Pharmacological activity of hyperforin acetate in rats.  

PubMed

Hyperforin, the main antidepressant component of Hypericum extract, is not stable with regard to heat and light. Therefore, we investigated a newly synthetized derivative, hyperforin acetate. Herein we demonstrate its efficacy in animal models sensitive to antidepressant and anxiolytic drugs. In the forced swimming test, triple administration of hyperforin (5-20 mg/kg) significantly reduced the immobility time of rats, while in the learned helplessness test a daily treatment of 10 mg/kg for seven consecutive days was necessary to elicit an antidepressant effect. In the elevated plus-maze and in the light-dark test, the acute administration of hyperforin acetate (3-5 mg/kg) exerted an anxiolytic activity, which, however, was smaller than that of diazepam. The effect was inhibited by the pretreatment of rats with metergoline, a serotoninergic antagonist, but not with CGS-8216, a benzodiazepine receptor antagonist. Hyperforin acetate (3-10 mg/kg) was also able to reduce locomotion in rats without eliciting myorelaxant activity. As Hypericum extract was claimed to exert a potential influence on the liver drug metabolizing system, we showed that neither acute nor repeated oral doses of hyperforin acetate altered pentobarbital sleeping time in rats. Taken together, the present results show that hyperforin acetate is a pharmacologically active derivative of hyperforin and may be a starting point from which to develop new compounds for therapeutic purposes. PMID:12478215

Zanoli, P; Rivasi, M; Baraldi, C; Baraldi, M

2002-12-01

180

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

SciTech Connect

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

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

2014-04-24

181

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

Microsoft Academic Search

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

Guanghua He; Hua Zheng; Fuliang Xiong

2008-01-01

182

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

NASA Astrophysics Data System (ADS)

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

Dabhi, Shweta; Jha, Prafulla K.

2014-04-01

183

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

E-print Network

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

184

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

185

Treatment of Pedophilia with Leuprolide Acetate  

Microsoft Academic Search

To date, the literature on the treatment of individuals who have committed sexual offenses has focused primarily on psychotherapeutic interventions and the use of antiandrogens. Recently case reports and small series supporting the efficacy of other psychiatric medication, such as serotonin reuptake inhibitors, have been published. Only a few publications have looked at the efficacy of leuprolide acetate, an LH-RH

Nancy Raymond; Bean Robinson; Chris Kraft; Barry Rittberg; Eli Coleman

2002-01-01

186

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

187

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

Microsoft Academic Search

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

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

2004-01-01

188

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

E-print Network

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

Van de Ven, James D.

189

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

Microsoft Academic Search

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

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

190

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

E-print Network

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

Peppas, Nicholas A.

191

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

192

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

Microsoft Academic Search

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

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

2006-01-01

193

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

Microsoft Academic Search

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

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

1999-01-01

194

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

PubMed

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

Meenakshi; Ahuja, Munish

2015-01-01

195

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

Microsoft Academic Search

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

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

2007-01-01

196

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

Microsoft Academic Search

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

J. Mayer; M. Szadkowska-Nicze

2006-01-01

197

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

Microsoft Academic Search

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

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

2000-01-01

198

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

Microsoft Academic Search

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

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

2004-01-01

199

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

Microsoft Academic Search

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

A Jiménez; L Torre; J. M Kenny

2001-01-01

200

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

Microsoft Academic Search

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

A. Sari; K. Kaygusuz

2007-01-01

201

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

Microsoft Academic Search

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

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

2009-01-01

202

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

203

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

Microsoft Academic Search

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

Shuxin Wang; Victor C. Li

204

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

Microsoft Academic Search

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

Mi-Jung Cho; Byung-Dae Park

2011-01-01

205

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

206

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

207

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

Microsoft Academic Search

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

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

208

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

Microsoft Academic Search

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

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

2002-01-01

209

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

Microsoft Academic Search

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

F. P. Altman; Terence Kennedy

1971-01-01

210

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

Microsoft Academic Search

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

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

2006-01-01

211

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

Microsoft Academic Search

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

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

212

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

213

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

Microsoft Academic Search

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

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

1992-01-01

214

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

Microsoft Academic Search

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

Masanori Kobayashi; Jyunya Toguchida; Masanori Oka

2003-01-01

215

Testing of polyvinyl alcohol and starch mixtures as biodegradable polymeric materials  

Microsoft Academic Search

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

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

2000-01-01

216

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

ERIC Educational Resources Information Center

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

Natarajan, L. V.; And Others

1983-01-01

217

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

218

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

219

Electrospinning processed nanofibrous TiO(2) membranes for photovoltaic applications.  

PubMed

We have recently fabricated dye-sensitized solar cells (DSSCs) comprising nanofibrous TiO(2) membranes as electrode materials. A thin TiO(2) film was pre-deposited on fluorine doped tin oxide (FTO) coated conducting glass substrate by immersion in TiF(4) 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 TiO(2) film coated FTO by electrospinning of a mixture of PVac and titanium isopropoxide in N,N-dimethylformamide (DMF). The nanofibrous TiO(2) membranes were obtained by calcining the electrospun composite nanofibres of PVac/titania as the precursor. Spectral sensitization of the nanofibrous TiO(2) 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 TiO(2) 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 TiO(2) membranes. The efficiency of the fibrous TiO(2) photoelectrode with the average membrane thickness of 3.9 µm has a maximum value of 4.14%. PMID:21727376

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

2006-02-28

220

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

221

Nanostructural surface engineering of grafted polymers on inorganic oxide substrates for membrane separations  

NASA Astrophysics Data System (ADS)

Nanostructural engineering of inorganic substrates by free radical graft polymerization was studied with the goal of developing new membrane materials for pervaporation. Graft polymerization consisted of modification of surface hydroxyls with vinyl trimethoxysilane, followed by solution graft polymerization reaction using either vinyl acetate (VAc) or vinyl pyrrolidone (VP). The topology of the modified surfaces was studied by atomic force microscopy (AFM) on both atomically smooth silicon wafer substrates and microporous inorganic membrane supports in order to deduce the effects of modification on the nanostructural properties of the membrane. While unmodified wafers showed a root-mean-square (RMS) surface roughness of 0.21 +/- 0.03 nm, roughness increased to 3.15 +/- 0.23 nm upon silylation. Under poor solvent conditions (i.e., air), surfaces modified with higher poly(vinyl acetate) (PVAc) or poly(vinyl pyrrolidone) (PVP) polymer graft yields displayed lateral inhomogeneities in the polymer layer. Although RMS surface roughness was nearly identical (0.81--0.85 nm) for PVAc-modified surfaces grafted at different monomer concentrations, the skewness of the height distribution decreased from 2.22 to 0.78 as polymer graft yield increased from 0.8 to 3.5 mg/m2. The polymer-modified surfaces were used to create inorganic pervaporation membranes consisting of a single macromolecular separation layer formed by graft polymerization. PVAc grafted silica membranes (500A native pore size) were found selective for MTBE in the separation of 0.1--1% (v/v) MTBE from water, achieving MTBE enrichment factors as high as 371 at a permeate flux of 0.38 l/m2 hr and a Reynolds number of 6390; however, these membranes could not separate anhydrous organic mixtures. Pervaporative separation of methanol/MTBE mixtures was possible with PVAc and PVP-modified alumina supports of 50A native pore size, where the separation layer consisted of grafted polymer chains with estimated radius of gyration 4.5--6.8 times larger than the membrane pore radius. Methanol separation factors for the PVP and PVAc-grafted alumina pervaporation membranes reached values of 26 and 100 (respectively) at total permeate fluxes of 0.055--1.26 kg/m 2 hr and 0.55--6.19 kg/m2 hr. The present study demonstrated that selective pervaporation membranes for separation of both organic/organic and organic/aqueous mixtures can be effectively designed by careful selection of the surface-grafted polymer chain density and the ratio of the polymer chain size to the native support pore size.

Yoshida, Wayne Hiroshi

222

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

223

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

224

21 CFR 582.5892 - a-Tocopherol acetate.  

Code of Federal Regulations, 2013 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5892 a -Tocopherol acetate. (a) Product. a -Tocopherol acetate. (b) Conditions...

2013-04-01

225

21 CFR 582.5892 - a-Tocopherol acetate.  

Code of Federal Regulations, 2011 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5892 a -Tocopherol acetate. (a) Product. a -Tocopherol acetate. (b) Conditions...

2011-04-01

226

21 CFR 582.5892 - a-Tocopherol acetate.  

Code of Federal Regulations, 2012 CFR

... ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5892 a -Tocopherol acetate. (a) Product. a -Tocopherol acetate. (b) Conditions...

2012-04-01

227

Gold-catalyzed cyclization of allenyl acetal derivatives  

PubMed Central

Summary The gold-catalyzed transformation of allenyl acetals into 5-alkylidenecyclopent-2-en-1-ones is described. The outcome of our deuterium labeling experiments supports a 1,4-hydride shift of the resulting allyl cationic intermediates because a complete deuterium transfer is observed. We tested the reaction on various acetal substrates bearing a propargyl acetate, giving 4-methoxy-5-alkylidenecyclopent-2-en-1-ones 4 via a degradation of the acetate group at the allyl cation intermediate. PMID:24062838

Vasu, Dhananjayan; Pawar, Samir Kundlik

2013-01-01

228

In vitro and in vivo evaluation of novel osmotic pump tablets of isosorbide-5-mononitrate containing polyvinyl pyrrolidone (PVP) for controlled release.  

PubMed

A novel osmotic pump tablet with ethyl cellulose (EC) and polyvinyl pyrrolidone (PVP) as the semipermeable membrane and isosorbide-5-mononitrate (5-ISMN) as the model drug was formulated in this study. Zero order release kinetics were attained by avoiding aging during storage. Drug release increased with an increase in the percentage of PVP K30 in the semipermeable membrane. However, drug release decreased with increased coating weight. Drug release rates decreased continuously for tablets coated with EC/PEG4000 and cellulose acetate (CA)/PEG4000. This tendency was more marked with longer storage time. However, there was little change in drug release rates for tablets with a semipermeable membrane of EC/PVP K30 at 6, 12 or 24 months. The weight loss test also validated the results mentioned above. The relative bioavailability of the osmotic-pump tablets against the reference formulation in single and multiple dose regimens was 116.7 and 106.5, respectively. This means that the bioavailability of osmotic pump tablets using PVP as the plasticiser was equal to that of the reference formulation. In general, 5-ISMN osmotic pump tablets with a semipermeable membrane composed of EC/PVP K30 may be useful in providing constant drug delivery with minimum fluctuations during longer storage time. PMID:22957434

Li, Xin; Jiang, Qingwei; Du, Lina; Wang, Chenyun; Chi, Qiang

2012-08-01

229

Isothermal decomposition of ?-irradiated samarium acetate  

NASA Astrophysics Data System (ADS)

Isothermal decomposition of un-irradiated and pre-?-irradiated samarium acetate has been investigated at different temperatures between 613 and 633 K. Irradiation was observed to enhance the rate of decomposition without modifying the mechanism of thermal decomposition. Thermal decomposition of samarium acetate has been shown to proceed by two-dimensional phase-boundary reaction both for un-irradiated and pre-?-irradiated samples. The enhancement of the decomposition was found to increase with an increase in the ?-ray dose applied to the sample and may be attributed to an increase in point defects and formation of additional nucleation centers generated in the host lattice. Thermodynamic values of the main decomposition process were calculated and evaluated.

Mahfouz, R. M.; Monshi, M. A. S.; Alshehri, S. M.; Abd El-Salam, N. M.

2000-10-01

230

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

231

Formation of acetic acid from cellulosic substrates by Fusarium oxysporum  

Microsoft Academic Search

Four strains of Fusarium oxysporum and a strain of Monilia brunnae were screened for their ability to convert cellulosic substrates into ethanol\\/acetic acid. These strains were found to utilize cellulose and produce extracellular cellulases. However, only F. oxysporum 841 was found to convert glucose, xylose, and cellulose into ethanol and acetic acid as major end-products under microaerobic conditions. Acetic acid

P. K. R. Kumar; Ajay Singh; K. Schiigerl

1991-01-01

232

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

233

Ammonia permeability of a cellulose acetate membrane  

Microsoft Academic Search

A mechanism is proposed for ammonia transport across a cellulose acetate membrane. The transport is shown to have a sorption\\u000a character, with the formation of hydrogen bonds between ammonia molecules and the polymer. Our experiments demonstrate that\\u000a the membrane can be regenerated in the course of gas separation. The ideal separation factors in the ammonia-nitrogen and\\u000a ammonia-hydrogen systems are determined.

I. V. Vorotyntsev; P. N. Drozdov; N. V. Karyakin

2006-01-01

234

Acetic acid bacteria as enantioselective biocatalysts  

Microsoft Academic Search

Acetic acid bacteria (five strains of Acetobacter and five strains of Gluconobacter) were used for the biotransformation of different primary alcohols (2-chloropropanol and 2-phenylpropanol) and diols (1,3-butandiol, 1,4-nonandiol and 2,3-butandiol). Most of the tested strains efficiently oxidized the substrates. 2-Chloropropanol and 1,3-butandiol were oxidized with good rates and low enantioselectivity (enantiomeric excess=18–46% of the S-acid), while microbial oxidation of 2-phenylpropanol

A Romano; R Gandolfi; P Nitti; M Rollini; F Molinari

2002-01-01

235

Nonenzymatic phosphorylation of acetate by carbamyl phosphate  

NASA Astrophysics Data System (ADS)

It is found that carbamyl phosphate is an efficient condensing agent for acetate and hydroxylamine in the presence of Be2+ and Al3+. The reaction has an optimum at pH 4 and is completed within 30 min. The yield of hydroxamate formation reaches 30% (based on initial carbamyl phosphate). Acetylphosphate as the intermediary product of this reaction was identified by P-NMR spectroscopy.

Saygin, Ömer

1983-03-01

236

Effect of ethyl acetate on carbohydrate components and crystalline structure of pulp produced in aqueous acetic acid pulping  

Microsoft Academic Search

The aim of this study was to investigate the changes in carbohydrate components and the crystalline structure in hemp bast\\u000a fibers by adding ethyl acetate to acetic acid\\/water pulping processes. It was found that ethyl acetate added to acetic acid\\/water\\u000a process had a positive effect on yield, viscosity and carbohydrate components in pulp. It was assumed that the delignification\\u000a ratio

Esat Gümü?kaya; Mustafa Usta; Mualla Balaban Uçar

2009-01-01

237

Evidence for a transition state analog, MgADP-aluminum fluoride-acetate, in acetate kinase from Methanosarcina thermophila.  

PubMed

Aluminum fluoride has become an important tool for investigating the mechanism of phosphoryl transfer, an essential reaction that controls a host of vital cell functions. Planar AlF(3) or AlF(4)(-) molecules are proposed to mimic the phosphoryl group in the catalytic transition state. Acetate kinase catalyzes phosphoryl transfer of the ATP gamma-phosphate to acetate. Here we describe the inhibition of acetate kinase from Methanosarcina thermophila by preincubation with MgCl(2), ADP, AlCl(3), NaF, and acetate. Preincubation with butyrate in place of acetate did not significantly inhibit the enzyme. Several NTPs can substitute for ATP in the reaction, and the corresponding NDPs, in conjunction with MgCl(2), AlCl(3), NaF, and acetate, inhibit acetate kinase activity. Fluorescence quenching experiments indicated an increase in binding affinity of acetate kinase for MgADP in the presence of AlCl(3), NaF, and acetate. These and other characteristics of the inhibition indicate that the transition state analog, MgADP-aluminum fluoride-acetate, forms an abortive complex in the active site. The protection from inhibition by a non-hydrolyzable ATP analog or acetylphosphate, in conjunction with the strict dependence of inhibition on the presence of both ADP and acetate, supports a direct in-line mechanism for acetate kinase. PMID:11960978

Miles, Rebecca D; Gorrell, Andrea; Ferry, James G

2002-06-21

238

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

Microsoft Academic Search

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

Ming Wang; Jiayou Xu; Hong Wu; Shaoyun Guo

2006-01-01

239

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

Microsoft Academic Search

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

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

2005-01-01

240

Overview on mechanisms of acetic acid resistance in acetic acid bacteria.  

PubMed

Acetic acid bacteria (AAB) are a group of gram-negative or gram-variable bacteria which possess an obligate aerobic property with oxygen as the terminal electron acceptor, meanwhile transform ethanol and sugar to corresponding aldehydes, ketones and organic acids. Since the first genus Acetobacter of AAB was established in 1898, 16 AAB genera have been recorded so far. As the main producer of a world-wide condiment, vinegar, AAB have evolved an elegant adaptive system that enables them to survive and produce a high concentration of acetic acid. Some researches and reviews focused on mechanisms of acid resistance in enteric bacteria and made the mechanisms thoroughly understood, while a few investigations did in AAB. As the related technologies with proteome, transcriptome and genome were rapidly developed and applied to AAB research, some plausible mechanisms conferring acetic acid resistance in some AAB strains have been published. In this review, the related mechanisms of AAB against acetic acid with acetic acid assimilation, transportation systems, cell morphology and membrane compositions, adaptation response, and fermentation conditions will be described. Finally, a framework for future research for anti-acid AAB will be provided. PMID:25575804

Wang, Bin; Shao, Yanchun; Chen, Fusheng

2015-02-01

241

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

242

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

SciTech Connect

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

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

2009-04-15

243

Polyvinyl alcohol-coated hybrid fiber grating for relative humidity sensing  

NASA Astrophysics Data System (ADS)

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

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

2011-07-01

244

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

PubMed

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

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

2000-07-01

245

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

SciTech Connect

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

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

1986-03-01

246

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

SciTech Connect

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

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

1986-10-10

247

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

248

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

SciTech Connect

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

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

1986-11-01

249

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

Microsoft Academic Search

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

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

2005-01-01

250

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

Microsoft Academic Search

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

P. Martens; K. S. Anseth

2000-01-01

251

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

Microsoft Academic Search

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

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

2008-01-01

252

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

Microsoft Academic Search

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

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

2012-01-01

253

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

Microsoft Academic Search

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

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

1990-01-01

254

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

Microsoft Academic Search

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

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

2010-01-01

255

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

Microsoft Academic Search

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

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

1991-01-01

256

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

Microsoft Academic Search

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

Nadia Ahmed Mohamed; Eljazi I. Al-afaleq

1999-01-01

257

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

NASA Astrophysics Data System (ADS)

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

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

1994-06-01

258

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

Microsoft Academic Search

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

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

2009-01-01

259

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

Microsoft Academic Search

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

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

2011-01-01

260

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

Microsoft Academic Search

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

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

1996-01-01

261

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

Microsoft Academic Search

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

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

2009-01-01

262

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

Microsoft Academic Search

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

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

1996-01-01

263

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

SciTech Connect

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

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

1994-05-01

264

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

SciTech Connect

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

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

1994-03-01

265

Properties and sorption studies of chitosan–polyvinyl alcohol blend films  

Microsoft Academic Search

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

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

2003-01-01

266

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

267

Nucleation of polyvinyl alcohol crystallization by single-walled carbon nanotubes  

Microsoft Academic Search

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

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

2004-01-01

268

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

Microsoft Academic Search

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

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

1997-01-01

269

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

Microsoft Academic Search

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

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

1996-01-01

270

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

271

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

272

Crystal growth of calcium carbonate on the cellulose acetate/pyrrolidon blend films in the presence of L-aspartic acid  

NASA Astrophysics Data System (ADS)

The morphogenesis and growth process of calcium carbonate on the cellulose acetate/polyvinyl pyrrolidone (CA/PVP) blend films in the presence of L-aspartic acid was carefully investigated. The results showed that the concentration of L-aspartic acid, the initial pH value of reaction solution and temperature turned out to be important factors for the control of morphologies and polymorphs of calcium carbonate. Complex morphologies of CaCO3 particles, such as cubes, rose-like spheres, twinborn-spheres, cone-like, bouquet-like, etc. could be obtained under the different experimental conditions. The dynamic process of formation of rose-like sphere crystals was analyzed by monitoring the continuous morphological and structural evolution and components of crystals in different crystal stages. This research may provide a promising method to prepare other inorganic materials with complex morphologies.

Zhang, Xiuzhen; Xie, Anjian; Huang, Fangzhi; Shen, Yuhua

2014-03-01

273

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

274

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

Microsoft Academic Search

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

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

1978-01-01

275

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

SciTech Connect

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

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

1988-04-01

276

Immunotoxicity of trenbolone acetate in Japanese quail  

USGS Publications Warehouse

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 the first study to date to assess this chemical's immunotoxic effects in an avian species. A one-time injection of trenbolone into yolks was administered to mimic maternal deposition, and subsequent effects on the development and function of the immune system were determined in chicks and adults. Development of the bursa of Fabricius, an organ responsible for development of the humoral arm of the immune system, was disrupted, as indicated by lower masse, and smaller and fewer follicles at day 1 of hatch. Morphological differences in the bursas persisted in adults, although no differences in either two measures of immune function were observed. Total numbers of circulating leukocytes were reduced and heterophil-lymphocyte ratios were elevated in chicks but not adults. This study shows that trenbolone acetate is teratogenic and immunotoxic in Japanese quail, and provides evidence that the quail immune system may be fairly resilient to embryonic endocrine-disrupting chemical-induced alterations following no further exposure posthatch.

Quinn, M.J.; McKernan, M.; Lavoie, E.T.; Ottinger, M.A.

2007-01-01

277

Atmospheric formic and acetic acids in Venezuela  

NASA Astrophysics Data System (ADS)

Gas, phase and rain concentrations of HCOOH and CH 3COOH have been measured at various sites in the savannah climatic region, a cloud forest site and a coastal site in Venezuela. Gas phase and rain water were sampled using the aqueous scrubber technique and a wet only collector, respectively. Analyses were made by ion chromatography. The results indicate that formic and acetic acids are important components of the Venezuelan atmosphere. They are homogeneously distributed, suggesting a widespread source. Boundary layer concentrations during the dry season (HCOOH, 1.8 ppbv; CH 3COOH, 1.25 ppbv) are higher than in the wet season (HCOOH, 1.0 ppbv; CH 3COOH, 0.7 ppbv), mainly due to a longer lifetime of the acid during the dry season (˜6 days) compared with the wet season (˜2 days). The overall concentrations in rain are 7.0 and 4.0 ?M for formic and acetic acids, respectively. The estimated annual total depositions are: HCOOH, 17 mmol m -2 yr -1 and CH 3COOH,10 mmol m -2 yr -1; around half of the acids are removed by dry deposition. It is established that a larger source (˜1.8 times) of both acids is present during the wet season. We speculate that atmospheric oxidation of hydrocarbons should be the main source of HCOOH and CH 3COOH in the Venezuelan atmosphere; soil emissions could make a significant contribution during the dry season.

Sanhueza, Eugenio; Figueroa, Luis; Santana, Magaly

278

40 CFR Table 2 to Subpart B of... - MON Source Categories  

Code of Federal Regulations, 2012 CFR

...Vinylidene Chloride Production. Polymethyl Methacrylate Resins Production. Polyvinyl Acetate Emulsions Production. Polyvinyl Alcohol Production. Polyvinyl Butyral Production. Ammonium Sulfate Production-Caprolactam...

2012-07-01

279

40 CFR Table 2 to Subpart B of... - MON Source Categories  

Code of Federal Regulations, 2014 CFR

...Vinylidene Chloride Production. Polymethyl Methacrylate Resins Production. Polyvinyl Acetate Emulsions Production. Polyvinyl Alcohol Production. Polyvinyl Butyral Production. Ammonium Sulfate Production-Caprolactam...

2014-07-01

280

40 CFR Table 2 to Subpart B of... - MON Source Categories  

Code of Federal Regulations, 2013 CFR

...Vinylidene Chloride Production. Polymethyl Methacrylate Resins Production. Polyvinyl Acetate Emulsions Production. Polyvinyl Alcohol Production. Polyvinyl Butyral Production. Ammonium Sulfate Production-Caprolactam...

2013-07-01

281

Crystal structure and chemical bonding in tin(II) acetate  

Microsoft Academic Search

Tin(II) acetate was prepared and its crystal structure was solved from X-ray powder diffraction data. Tin(II) acetate adopts a polymeric structure consisting of infinite Sn(CH3COO)2 chains running along the c-axis which are packed into groups of four. The acetate groups bridge the Sn atoms along the chains. The Sn atoms are asymmetrically surrounded by four oxygen atoms with two short

Varvara S. Stafeeva; Alexander S. Mitiaev; Artem M. Abakumov; Alexander A. Tsirlin; Artem M. Makarevich; Evgeny V. Antipov

2007-01-01

282

The acetate kinase of Clostridum acetobutylicum strain P262  

Microsoft Academic Search

Clostridum acetobutylicum strain P262 fermented glucose, pyruvate, or lactate, and the butyrate production was substrate-dependent. Differences in butyrate yield could not be explained by changes in butyrate kinase activities, but the butyrate production was inversely related to acetate kinase activity. The acetate kinase had a pH optimum of 8.0, aKm for acetate of 160 mM, and akcat of 16,800 min-1.

Francisco Diez-Gonzalez; James B. Russell; Jean B. Hunter

1996-01-01

283

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

284

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

PubMed

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

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

2013-08-01

285

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

286

N-(2-Chloro-acet-yl)glycine.  

PubMed

The title compound, C4H6ClNO3, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In each mol-ecule, there are N-H?O and N-H?Cl hydrogen bonds. Both mol-ecules are relatively planar, with the mean plane of the acetamide [N-C(=O)C] group being inclined to the mean plane of the acetate group [C-C(=O)O] by 9.23?(13)° in mol-ecule A and 6.23?(12)° in mol-ecule B. In the crystal, adjacent mol-ecules are linked by O-H?O hydrogen bonds and weak C-H?O contacts forming -A-A-A- and -B-B-B- parallel chains propagating along the a-axis direction. PMID:24454136

Zhang, Yu-Cheng; Zhang, Xiu-Qin; Wang, Kai; Chen, Qiang

2013-10-26

287

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

288

Oxidation of Indole-3-Acetic Acid to Oxindole-3-Acetic Acid by an Enzyme Preparation from Zea mays1  

PubMed Central

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. PMID:11538238

Reinecke, Dennis M.; Bandurski, Robert S.

1988-01-01

289

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

290

Heterogeneous catalyst for the production of acetic anhydride from methyl acetate  

DOEpatents

This invention relates to a process for producing acetic anhydride by the reaction of methyl acetate, carbon monoxide, and hydrogen at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that contains an insoluble polymer having pendant quaternized phosphine groups, some of which phosphine groups are ionically bonded to anionic Group VIII metal complexes, the remainder of the phosphine groups being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for consecutive runs without loss in activity. Bifunctional catalysts for use in carbonylating dimethyl ether are also provided.

Ramprasad, D.; Waller, F.J.

1999-04-06

291

Heterogeneous catalyst for the production of acetic anhydride from methyl acetate  

DOEpatents

This invention relates to a process for producing acetic anhydride by the reaction of methyl acetate, carbon monoxide, and hydrogen at elevated temperatures and pressures in the presence of an alkyl halide and a heterogeneous, bifunctional catalyst that contains an insoluble polymer having pendant quaternized phosphine groups, some of which phosphine groups are ionically bonded to anionic Group VIII metal complexes, the remainder of the phosphine groups being bonded to iodide. In contrast to prior art processes, no accelerator (promoter) is necessary to achieve the catalytic reaction and the products are easily separated from the catalyst by filtration. The catalyst can be recycled for consecutive runs without loss in activity. Bifunctional catalysts for use in carbonylating dimethyl ether are also provided.

Ramprasad, Dorai (Allentown, PA); Waller, Francis Joseph (Allentown, PA)

1999-01-01

292

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

293

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

PubMed

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

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

1991-12-01

294

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

NASA Astrophysics Data System (ADS)

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

Gongxu, Lü; Hongying, Chen; Dongyuan, Liu

1993-07-01

295

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

NASA Astrophysics Data System (ADS)

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

Cui, Xiaojie; Li, Luming; Xu, Fu

2011-04-01

296

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

PubMed

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

Andersson, B

1988-07-22

297

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

298

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

NASA Technical Reports Server (NTRS)

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

Pepper, S. V.

1974-01-01

299

Near ultraviolet photodetector fabricated from polyvinyl-alcohol coated In2O3 nanoparticles  

NASA Astrophysics Data System (ADS)

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

Shao, Dali; Qin, Liqiao; Sawyer, Shayla

2012-11-01

300

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

PubMed

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

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

2008-12-10

301

Cross-linked polyvinyl alcohols and oil reservoir permeability control therewith  

SciTech Connect

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

Hoskin, D.H.; Shu, P.

1990-01-30

302

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

PubMed Central

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

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

2012-01-01

303

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

PubMed

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

Li, Dongsheng; Cao, Hai

2012-01-01

304

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

E-print Network

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

Peppas, Nicholas A.

305

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

306

Selective perborate signaling by deprotection of fluorescein and resorufin acetates.  

PubMed

The acetate derivatives of fluorescein and resorufin exhibited a prominent turn-on type signaling behavior toward BO(3)(-) ions over other common anions. Signaling is based on the selective deprotection of acetate groups by perborate, which resulted in significant chromogenic and fluorogenic signaling. Compound 1 also exhibited a pronounced perborate selectivity over other commonly used oxidants in 90% aqueous acetonitrile solution. PMID:20222739

Choi, Myung Gil; Cha, Sunyoung; Park, Ji Eun; Lee, Haekyung; Jeon, Hye Lim; Chang, Suk-Kyu

2010-04-01

307

Introduction Metal acetates are used as metal precursors in many  

E-print Network

facilitated exploring broader applications of metal and metal oxide nanoparticles by utilizing the synthesis properties of the solid phase metal acetate precursors and the product metal/metal oxide nanocomposite in these combustion and other synthesis systems which rely on thermal decomposition and oxidation of metal acetates [6

Wooldridge, Margaret S.

308

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

309

Enrichment of amino acid-oxidizing, acetate-reducing bacteria.  

PubMed

In anaerobic condition, amino acids are oxidatively deaminated, and decarboxylated, resulting in the production of volatile fatty acids. In this process, excess electrons are produced and their consumption is necessary for the accomplishment of amino acid degradation. In this study, we anaerobically constructed leucine-degrading enrichment cultures from three different environmental samples (compost, excess sludge, and rice field soil) in order to investigate the diversity of electron-consuming reaction coupled to amino acid oxidation. Constructed enrichment cultures oxidized leucine to isovalerate and their activities were strongly dependent on acetate. Analysis of volatile fatty acids (VFAs) profiles and community structure analysis during batch culture of each enrichment indicated that Clostridium cluster I coupled leucine oxidation to acetate reduction in the enrichment from the compost and the rice field soil. In these cases, acetate was reduced to butyrate. On the other hand, Clostridium cluster XIVb coupled leucine oxidation to acetate reduction in the enrichment from the excess sludge. In this case, acetate was reduced to propionate. To our surprise, the enrichment from rice field soil oxidized leucine even in the absence of acetate and produced butyrate. The enrichment would couple leucine oxidation to reductive butyrate synthesis from CO2. The coupling reaction would be achieved based on trophic link between hydrogenotrophic acetogenic bacteria and acetate-reducing bacteria by sequential reduction of CO2 and acetate. Our study suggests anaerobic degradation of amino acids is achieved yet-to-be described reactions. PMID:24630616

Ato, Makoto; Ishii, Masaharu; Igarashi, Yasuo

2014-08-01

310

Acetic acid pulping of wheat straw under atmospheric pressure  

Microsoft Academic Search

Atmospheric acetic acid pulping of wheat straw was carried out. Pulping conditions and their effects on pulp properties were investigated in detail, and a comparison between acetic acid (AcOH) pulp and soda-anthraquinone (AQ) pulps of wheat straw was made of the chemical com- position, strength, and fiber morphology of the pulps. Wheat straw was successfully pulped and fractionated into pulp

Xue-Jun PanYoshihiro Sano

1999-01-01

311

Polymer coating of paramagnetic particulates for in vivo oxygen-sensing applications.  

PubMed

Crystalline lithium phthalocyanine (LiPc) can be used to sense oxygen. To enhance biocompatibility/stability of LiPc, we encapsulated LiPc in Teflon AF (TAF), cellulose acetate (CA), and polyvinyl acetate (PVAc) (TAF, previously used to encapsulate LiPc, was a comparator). We identified water-miscible solvents that don't dissolve LiPc crystals, but are solvents for the polymers, and encapsulated crystals by solvent evaporation. Oxygen sensitivity of films was characterized in vitro and in vivo. Encapsulation did not change LiPc oximetry properties in vitro at anoxic conditions or varying partial pressures of oxygen (pO2). EPR linewidth of encapsulated particles was linear with pO2, responding to pO2 changes quickly and reproducibly for dynamic measurements. Encapsulated LiPc was unaffected by biological oxidoreductants, stable in vivo for four weeks. Oximetry, stability and biocompatibility properties of LiPc films were comparable, but both CA and PVAc films are cheaper, and easier to fabricate and handle than TAF films, making them superior. PMID:19083100

Eteshola, Edward; Pandian, Ramasamy P; Lee, Stephen C; Kuppusamy, Periannan

2009-04-01

312

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

313

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

Microsoft Academic Search

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

Wilma M. Frederiks; Frans Marx

1988-01-01

314

Mechanical Properties and a Physical-Chemical Analysis of Acetate Yarns  

Microsoft Academic Search

Cellulose acetate used in the manufacture of acetate yarns is commonly obtained from cotton-linters or wood-pulp cellulose. Varying in the origin and in the manufacturer, cellulose acetate often differs in its processability. The paper belongs to the investigation the properties of acetate yarns manufactured of the cellulose acetate varied in its origin and manufactured by different suppliers. Mechanical properties (including

R. emaitaitien?; A. Vitkauskas

315

Selective deprotection of acetals with Me3SiCH2MgCl. Peterson-type olefination of acetals  

PubMed

By employing the chelation strategy, treatment of an acetal of a contiguous diol with Me3SiCH2MgCl liberates the corresponding diol regioselectively. In addition, acetals of different structural variety are transformed upon treatment with Me3SiCH2MgCl and ZnI2 into the corresponding olefination products in good yield. PMID:10959876

Chiang; Chen; Hsieh; Luh

2000-07-28

316

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

SciTech Connect

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

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

1992-03-01

317

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

318

Oxidation of Indole-3-acetic Acid and Oxindole-3-acetic Acid to 2,3-Dihydro-7-hydroxy-2-oxo-1H Indole-3-acetic Acid-7?-O-?-d-Glucopyranoside in Zea mays Seedlings 1  

PubMed Central

Radiolabeled oxindole-3-acetic acid was metabolized by roots, shoots, and caryopses of dark grown Zea mays seedlings to 2,3-dihydro-7-hydroxy-2-oxo-1H indole-3-acetic acid-7?-O-?-d-glycopyranoside with the simpler name of 7-hydroxyoxindole-3-acetic acid-glucoside. This compound was also formed from labeled indole-3-acetic acid supplied to intact seedlings and root segments. The glucoside of 7-hydroxyoxindole-3-acetic acid was also isolated as an endogenous compound in the caryopses and shoots of 4-day-old seedlings. It accumulates to a level of 4.8 nanomoles per plant in the kernel, more than 10 times the amount of oxindole-3-acetic acid. In the shoot it is present at levels comparable to that of oxindole-3-acetic acid and indole-3-acetic acid (62 picomoles per shoot). We conclude that 7-hydroxyoxindole-3-acetic acid-glucoside is a natural metabolite of indole-3-acetic acid in Z. mays seedlings. From the data presented in this paper and in previous work, we propose the following route as the principal catabolic pathway for indole-3-acetic acid in Zea seedlings: Indole-3-acetic acid ? Oxindole-3-acetic acid ? 7-Hydroxyoxindole-3-acetic acid ? 7-Hydroxyoxindole-3-acetic acid-glucoside. PMID:11540902

Nonhebel, Heather M.; Bandurski, Robert S.

1984-01-01

319

Biodegradable cellulose acetate nanofiber fabrication via electrospinning.  

PubMed

Nanofiber manufacturing is one of the key advancements in nanotechnology today. Over the past few years, there has been a tremendous growth of research activities to explore electrospinning for nanofiber formation from a rich variety of materials. This quite simple and cost effective process operates on the principle that the solution is extracted under the action of a high electric field. Once the voltage is sufficiently high, a charged jet is ejected following a complicated looping trajectory. During its travel, the solvent evaporates leaving behind randomly oriented nanofibers accumulated on the collector. The combination of their nanoscale dimensionality, high surface area, porosity, flexibility and superior strength makes the electrospun fibers suitable for several value-added applications, such as filters, protecting clothes, high performance structures and biomedical devices. In this study biodegradable cellulose acetate (CA) nanofibrous membranes were produced using electrospinning. The device utilized consisted of a syringe equipped with a metal needle, a microdialysis pump, a high voltage supply and a collector. The morphology of the yielded fibers was determined using SEM. The effect of various parameters, including electric field strength, tip-to-collector distance, solution feed rate and composition on the morphological features of the electrospun fibers was examined. The optimum operating conditions for the production of uniform, non-beaded fibers with submicron diameter were also explored. The biodegradable CA nanofiber membranes are suitable as tissue engineering scaffolds and as reinforcements of biopolymer matrix composites in foils by ultrasonic welding methods. PMID:21133179

Christoforou, Theopisti; Doumanidis, Charalabos

2010-09-01

320

Micelles Protect and Concentrate Activated Acetic Acid  

NASA Astrophysics Data System (ADS)

As more and more exoplanets are discovered and the habitability of such planets is considered, one can turn to searching for the origin of life on Earth in order to better understand what makes a habitable planet. Activated acetic acid, or methyl thioacetate, has been proposed to be central to the origin of life on Earth, and also as an important energy currency molecule in early cellular evolution. We have investigated the hydrolysis of methyl thioacetate under various conditions. Its uncatalyzed rate of hydrolysis is about three orders of magnitude faster (K = 0.00663 s^-1; 100°C, pH 7.5, concentration = 0.33mM) than published rates for its catalyzed production making it unlikely to accumulate under prebiotic conditions. However, we also observed that methyl thioacetate was protected from hydrolysis when inside its own hydrophobic droplets. We found that methyl thioacetate protection from hydrolysis was also possible in droplets of hexane and in the membranes of nonanoic acid micelles. Thus, the hydrophobic regions of prebiotic micelles and early cell membranes could have offered a refuge for this energetic molecule increasing its lifetime in close proximity to the reactions for which it would be needed. Methyl thioacetate could thus be important for the origin of life on Earth and perhaps for better understanding the potential habitability of other planets.

Todd, Zoe; House, C.

2014-01-01

321

Computerized image analysis for acetic acid induced intraepithelial lesions  

NASA Astrophysics Data System (ADS)

Cervical Intraepithelial Neoplasia (CIN) exhibits certain morphologic features that can be identified during a visual inspection exam. Immature and dysphasic cervical squamous epithelium turns white after application of acetic acid during the exam. The whitening process occurs visually over several minutes and subjectively discriminates between dysphasic and normal tissue. Digital imaging technologies allow us to assist the physician analyzing the acetic acid induced lesions (acetowhite region) in a fully automatic way. This paper reports a study designed to measure multiple parameters of the acetowhitening process from two images captured with a digital colposcope. One image is captured before the acetic acid application, and the other is captured after the acetic acid application. The spatial change of the acetowhitening is extracted using color and texture information in the post acetic acid image; the temporal change is extracted from the intensity and color changes between the post acetic acid and pre acetic acid images with an automatic alignment. The imaging and data analysis system has been evaluated with a total of 99 human subjects and demonstrate its potential to screening underserved women where access to skilled colposcopists is limited.

Li, Wenjing; Ferris, Daron G.; Lieberman, Rich W.

2008-03-01

322

The Effects of Acetate Buffer Concentration on Lysozyme Solubility  

NASA Technical Reports Server (NTRS)

The micro-solubility column technique was employed to systematically investigate the effects of buffer concentration on tetragonal lysozyme solubility. While keeping the NaCl concentrations constant at 2%, 3%, 4%, 5% and 7%, and the pH at 4.0, we have studied the solubility of tetragonal lysozyme over an acetate buffer concentration range of 0.01M to 0.5M as a function of temperature. The lysozyme solubility decreased with increasing acetate concentration from 0.01M to 0.1M. This decrease may simply be due to the net increase in solvent ionic strength. Increasing the acetate concentration beyond 0.1M resulted in an increase in the lysozyme solubility, which reached a peak at - 0.3M acetate concentration. This increase was believed to be due to the increased binding of acetate to the anionic binding sites of lysozyme, preventing their occupation by chloride. In keeping with the previously observed reversal of the Hoffmeister series for effectiveness of anions in crystallizing lysozyme, acetate would be a less effective precipitant than chloride. Further increasing the acetate concentration beyond 0.3M resulted in a subsequent gradual decrease in the lysozyme solubility at all NaCl concentrations.

Forsythe, Elizabeth L.; Pusey, Marc L.

1996-01-01

323

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

Federal Register 2010, 2011, 2012, 2013, 2014

...DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and...Levomethadyl Acetate Hydrochloride) Oral Solution, 10 Milligrams/Milliliter...acetate hydrochloride (HCl)) oral solution, 10 milligrams (mg...for levomethadyl acetate HCl oral solution, 10 mg/mL, if...

2011-06-06

324

Selective Cross-Coupling of Organic Halides with Allylic Acetates  

PubMed Central

A general protocol for the coupling of haloarenes with a variety of allylic acetates is presented. Strengths of the method are a tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) substrates and the ability to couple with a variety of substituted allylic acetates. Secondary alkyl bromides can also be allylated under slightly modified conditions, demonstrating the generality of the approach. Finally, the coupling of a reactive vinyl halide could be achieved by the use of a very hindered ligand and more reactive, branched allylic acetates. PMID:23095043

Anka-Lufford, Lukiana L.; Prinsell, Michael R.

2012-01-01

325

Selective cross-coupling of organic halides with allylic acetates.  

PubMed

A general protocol for the coupling of haloarenes with a variety of allylic acetates is presented. Strengths of the method are a tolerance for electrophilic (ketone, aldehyde) and acidic (sulfonamide, trifluoroacetamide) substrates and the ability to couple with a variety of substituted allylic acetates. Secondary alkyl bromides can also be allylated under slightly modified conditions, demonstrating the generality of the approach. Finally, the coupling of a reactive vinyl halide could be achieved by the use of a very hindered ligand and more reactive, branched allylic acetates. PMID:23095043

Anka-Lufford, Lukiana L; Prinsell, Michael R; Weix, Daniel J

2012-11-16

326

Patterned cell arrays and patterned co-cultures on polydopamine-modified poly(vinyl alcohol) hydrogels.  

PubMed

Live cell arrays are an emerging tool that expand traditional 2D in vitro cell culture, increasing experimental precision and throughput. A patterned cell system was developed by combining the cell-repellent properties of polyvinyl alcohol hydrogels with the cell adhesive properties of self-assembled films of dopamine (polydopamine). It was shown that polydopamine could be patterned onto spin-cast polyvinyl alcohol hydrogels by microcontact printing, which in turn effectively patterned the growth of several cell types (HeLa, human embryonic kidney, human umbilical vein endothelial cells (HUVEC) and prostate cancer). The cells could be patterned in geometries down to single-cell confinement, and it was demonstrated that cell patterns could be maintained for at least 3 weeks. Furthermore, polydopamine could be used to modify poly(vinyl alcohol) in situ using a cell-compatible deposition buffer (1 mg mL(-1) dopamine in 25 mM tris with a physiological salt balance). The treatment switched the PVA hydrogel from cell repellent to cell adhesive. Finally, by combining microcontact printing and in situ deposition of polydopamine, patterned co-cultures of the same cell type (HeLa/HeLa) and dissimilar cell types (HeLa/HUVEC) were realized through simple chemistry and could be studied over time. The combination of polyvinyl alcohol and polydopamine was shown to be an attractive route to versatile, patterned cell culture experiments with minimal infrastructure requirements and low complexity. PMID:24280598

Beckwith, Kai M; Sikorski, Pawel

2013-12-01

327

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 ...

328

Structural and magnetic properties of nanoscale iron oxide particles synthesized in the presence of dextran or polyvinyl alcohol  

Microsoft Academic Search

Magnetite\\/maghemite nanoparticles were synthesized in the presence of either dextran or polyvinyl alcohol, yielding cluster- and necklace-like aggregates, respectively. Magnetization, Mössbauer spectroscopy, and microscopy measurements indicate that the arrangement of the particles within the aggregates affects the magnetic properties of the particles resulting in smaller particles in the clusters having higher superparamagnetic blocking temperatures than larger particles in the necklaces.

Heath Pardoe; Wanida Chua-anusorn; Timothy G. St. Pierre; Jon Dobson

2001-01-01

329

Photocrosslinkable polyvinyl alcohol hydrogels that can be modified with cell adhesion peptides for use in tissue engineering  

Microsoft Academic Search

Photoactive polyvinyl alcohol hydrogels (PVA) have been investigated for use as tissue engineering scaffolds. These materials allow in situ polymerization for minimally invasive implantation methods. The mechanical properties of these materials can be tailored for a variety of soft tissue applications. The Young's modulus and ultimate tensile strength of PVA hydrogels are increased with increasing polymer concentration, and highly elastic

Rachael H. Schmedlen; Kristyn S. Masters; Jennifer L. West

2002-01-01

330

Fabrication and operation of a system for the PVA (polyvinyl alcohol) coating of polymer microshells with trace gas fill  

SciTech Connect

Polymer microshells with a PVA (polyvinyl alcohol) coating are produced for the ICF Program by the Fusion Target Fabrication (FTF) Group at Lawrence Livermore National Laboratories. A PVA coating greatly reduces the permeation of gas through a polymer microshell. The equipment and procedures used in the production of PVA coated microshells are discussed. 6 figs.

King, K.J.

1988-03-31

331

The histochemical localization of lactic dehydrogenase isoenzymes in the rat nephron by means of an improved polyvinyl alcohol method  

Microsoft Academic Search

The histochemical localization of lactic dehydrogenase (LDH) activity and the prevailing type of isoenzyme in different segments of the nephron in male and female rats are described. Polyvinyl alcohol was added to the incubation medium in order to reduce enzyme diffusion. Localization of the reaction product was further improved by the use of a high concentration of Nitro BT (and

N. O. Jacobsen

1969-01-01

332

Chemical treatment of membranes of a polymer blend: Mechanism of the reaction of hypochlorite with poly(vinyl pyrrolidone)  

Microsoft Academic Search

Sodium hypochlorite solutions are used to treat membranes prepared from a polymeric blend containing poly(vinyl pyrrolidone) (PVP) to increase their water permeability. Sodium hypochlorite affects the membrane material in such a way that PVP is selectively removed from the membrane matrix. The mechanism of the reaction between hypochlorite and PVP is investigated by several chemical analysis techniques of the reaction

I. M. Wienk; E. E. B. Meuleman; Z. Borneman; Th. van den Boomgaard; C. A. Smolders

1995-01-01

333

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

334

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 ...

335

Porphyria variegata treated with cyproterone acetate and ethinyl estradiol.  

PubMed

The cyclical use of cyproterone acetate and ethinyl estradiol successfully prevented attacks of abdominal pain in a 30-year-old woman suffering from porphyria variegata. Blistering still appeared following light exposure, but possibly to a lesser degree. PMID:6873421

Zachariae, H; Cramers, M

1983-01-01

336

Disposition of eslicarbazepine acetate in the mouse after oral administration.  

PubMed

Eslicarbazepine acetate is a promising antiepileptic drug structurally related to carbamazepine and oxcarbazepine, which is in the final phase of clinical development. The metabolism of eslicarbazepine acetate is clearly species dependent and, in this case, among small laboratory animals, the mouse seems to be the most relevant species to humans. Hence, the aim of this study was to investigate the plasma, brain and liver disposition of eslicarbazepine acetate in mice to better understand its disposition in humans. Adult male CD-1 mice were treated orally with a single dose of eslicarbazepine acetate 350 mg/kg. Blood samples, brain and liver tissues were taken at 0.25, 0.5, 0.75, 1, 2, 4, 6, 10, 16 and 24 h post-dose. Plasma and tissue levels of eslicarbazepine acetate and its metabolites (S-licarbazepine, R-licarbazepine and oxcarbazepine) were assessed by using high-performance liquid chromatography-ultraviolet detection. Both eslicarbazepine acetate and R-licarbazepine concentrations were below the limit of quantification of the assay in all matrices. Eslicarbazepine acetate was rapidly and extensively metabolized to S-licarbazepine (major metabolite), which was oxidized to oxcarbazepine to a small extent. The brain/plasma ratios suggest that the brain exposure to S-licarbazepine and oxcarbazepine was approximately 30% of their total systemic exposure. However, S-licarbazepine crossed the blood-brain barrier (BBB) less efficiently than oxcarbazepine. On the other hand, the liver/plasma ratios support the notion that S-licarbazepine undergoes hepatic accumulation, whereas oxcarbazepine appears to leave this compartment twice as fast as S-licarbazepine. Thus, the diffusion through the BBB is favourable to oxcarbazepine and the liver acts like a deposit of the pharmacologically active metabolite of eslicarbazepine acetate (S-licarbazepine). PMID:18710399

Alves, Gilberto; Figueiredo, Isabel; Castel-Branco, Margarida; Lourenço, Nulita; Falcão, Amílcar; Caramona, Margarida; Soares-da-Silva, Patrício

2008-10-01

337

Acetate transiently inhibits myocardial contraction by increasing mitochondrial calcium uptake.  

PubMed

BackgroundThere is a close relationship between cardiovascular disease and cardiac energy metabolism, and we have previously demonstrated that palmitate inhibits myocyte contraction by increasing Kv channel activity and decreasing the action potential duration. Glucose and long chain fatty acids are the major fuel sources supporting cardiac function; however, cardiac myocytes can utilize a variety of substrates for energy generation, and previous studies demonstrate the acetate is rapidly taken up and oxidized by the heart. In this study, we tested the effects of acetate on contractile function of isolated mouse ventricular myocytes.ResultsAcute exposure of myocytes to 10 mM sodium acetate caused a marked, but transient, decrease in systolic sarcomere shortening (1.49¿±¿0.20% vs. 5.58¿±¿0.49% in control), accompanied by a significant increase in diastolic sarcomere length (1.81¿±¿0.01 ¿m vs. 1.77¿±¿0.01 ¿m in control), with a near linear dose response in the 1¿10 mM range. Unlike palmitate, acetate caused no change in action potential duration; however, acetate markedly increased mitochondrial Ca2+ uptake. Moreover, pretreatment of cells with the mitochondrial Ca2+ uptake blocker, Ru-360 (10 ¿M), markedly suppressed the effect of acetate on contraction.ConclusionsLehninger and others have previously demonstrated that the anions of weak aliphatic acids such as acetate stimulate Ca2+ uptake in isolated mitochondria. Here we show that this effect of acetate appears to extend to isolated cardiac myocytes where it transiently modulates cell contraction. PMID:25488103

Schooley, James F; Namboodiri, Aryan M A; Cox, Rachel T; Bünger, Rolf; Flagg, Thomas P

2014-12-01

338

Acetic acid pulping of wheat straw under atmospheric pressure  

Microsoft Academic Search

Atmospheric acetic acid pulping of wheat straw was carried out. Pulping conditions and their effects on pulp properties were\\u000a investigated in detail, and a comparison between acetic acid (AcOH) pulp and soda-anthraquinone (AQ) pulps of wheat straw\\u000a was made of the chemical composition, strength, and fiber morphology of the pulps. Wheat straw was successfully pulped and\\u000a fractionated into pulp (cellulose),

Xue-Jun Pan; Yoshihiro Sano

1999-01-01

339

Microorganisms having enhanced resistance to acetate and methods of use  

SciTech Connect

The present invention provides isolated or genetically modified strains of microorganisms that display enhanced resistance to acetate as a result of increased expression of a sodium proton antiporter. The present invention also provides methods for producing such microbial strains, as well as related promoter sequences and expression vectors. Further, the present invention provides methods of producing alcohol from biomass materials by using microorganisms with enhanced resistance to acetate.

Brown, Steven D; Yang, Shihui

2014-10-21

340

Synthesis of coprecipitated strontium hexaferrite nanoparticles in the presence of polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

Strontium hexaferrite (SrFe12O19) nanoparticles were synthesized by the chemical coprecipitation method and using polyvinyl alcohol (PVA) as a protective agent. The synthesized samples were characterized by differential thermal analysis, X-ray diffraction, scanning and transmission electron microscopy, particle size analyzer, sedimentation test and vibrating sample magnetometer. In the presence of PVA, the single-phase SrFe12O19 nanoparticles were obtained at low temperature of 650 °C. The average particle size of SrFe12O19 precursor was 15 nm, which increased to 61 nm after calcination at 650 °C. The magnetic measurements indicated that PVA decreased coercivity from 4711 to 3216 Oe with particle size reduction. The results showed that PVA as a protective agent could be effective in decreasing the particle size, calcination temperature and coercivity of SrFe12O19 nanoparticles.

Davoodi, A.; Hashemi, B.; Yousefi, M. H.

2011-12-01

341

Identification of diffusive transport properties of poly(vinyl alcohol) hydrogels from reservoir test.  

PubMed

In this paper the identification of diffusion coefficient, retardation factor and surface distribution coefficient for selected salts in poly(vinyl alcohol) hydrogels is performed. The identification of the transport parameters is based on the previously developed inverse problem technique using experimental data from the reservoir test and the solution of the diffusive transport equation with linear equilibrium sorption. The estimated values of diffusion coefficient are: for physiological fluid (6.30±0.10)×10(-10) m(2)/s, for 1 M NaCl (6.42±0.39)×10(-10) m(2)/s, and for 1 M KCl (7.94±0.38)×10(-10) m(2)/s. The retardation factor for all tested materials and salts is equal or close to one. The average value of the effective surface distribution coefficient is equal to 0.5. PMID:24094156

Kazimierska-Drobny, Katarzyna; Kaczmarek, Mariusz

2013-12-01

342

Characterization and potential applications of gamma irradiated chitosan and its blends with poly(vinyl alcohol).  

PubMed

Naturally available chitosan (CHI), of high molecular weight, results in reduced efficiency of these polymers for antibacterial activity. In this regard, irradiation is a widely used method for achieving reduction in molecular weight of polymers, which may improve some of its characteristics. Chitosan was extracted from crab shells and degraded by gamma radiations. Effect of radiation dose on chitosan was analyzed by Fourier transform infrared (FTIR) spectroscopy. Furthermore, the irradiated chitosan was blended with poly(vinyl alcohol) (PVA) and crosslinked with tetraethylorthosilicate (TEOS) into membranes. The membranes were found to be smooth, transparent and macroporous in structure, exhibiting high tensile strength (TS: 27-47 MPa) and elongation at break (EB: 292.6-407.3%). The effect of molecular weight of chitosan and chitosan blends on antibacterial activity was determined. Irradiated low molecular weight chitosan and membranes showed strong antibacterial activity against Escherichia coli and Bacillus subtilis. PMID:24418341

Bano, Ijaz; Ghauri, Muhammad Afzal; Yasin, Tariq; Huang, Qingrong; Palaparthi, Annie D'Souza

2014-04-01

343

Peptide-decorated polyvinyl alcohol/hyaluronan nanofibers for human induced pluripotent stem cell culture.  

PubMed

Realization of the full potential of human induced pluripotent stem cells (hiPSCs) in clinical applications requires development of well-defined conditions for their growth and differentiation. A novel fully defined polyvinyl alcohol/hyaluronan (PVA/HA) polysaccharide nanofiber was developed for hiPSCs culture in commercially available xeno-free, chemically defined medium. Vitronectin peptide (VP) was immobilized to PVA/HA nanofibers through NHS/EDC chemistry. The hiPSCs successfully grew and proliferated on the VP-decorated PVA/HA nanofibers, similar to those on Matrigel™. Such well-defined, xeno-free and safe nanofiber substrate that supports culture of hiPSCs will not only help to accelerate the translational perspectives of hiPSCs, but also provide a platform to investigate the cell-nanofiber interaction mechanisms that regulate stem cell proliferation and differentiation. PMID:24299746

Deng, Yi; Zhang, Xiaohong; Zhao, Yinghui; Liang, Shangshang; Xu, Anxiu; Gao, Xiang; Deng, Feng; Fang, Jing; Wei, Shicheng

2014-01-30

344

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

345

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

346

Spectral-Polarization Properties and Light Resistance of Polyvinyl-Alcohol Films Colored With Disazo Dyes  

NASA Astrophysics Data System (ADS)

Polarizers containing disazo dyes from the group of azobenzene-azonaphthalene have been developed. It has been established that their polarizing ability is determined by the mutual disposition of the azo group and electron-donor substituents in the naphthalene ring. On diazo coupling of ? acid into the ? position relative to the oxy group, the M1 and M3 dyes are formed, the polarizing ability of which in uniaxially oriented polyvinyl-alcohol films is higher than in the M2 dye produced as a result of diazo coupling into the ? position relative to the amino group. On irradiation by UV light, the dyes are subjected to photodestruction, which, in the case of M2, proceeds through trans-cis-isomerization. The rate of photodestruction depends on the aggregation of the dye molecules, and it increases in the presence of a free-radical initiator. The UV absorber (substituted benzotriazole) and the uniaxial orientation of the film retard this process.

Fillipovich, L. N.; Ariko, N. G.; Agabekov, V. E.; Malashko, P. M.

2005-09-01

347

Asymmetric supercapacitor based on nanostructured graphene foam/polyvinyl alcohol/formaldehyde and activated carbon electrodes  

NASA Astrophysics Data System (ADS)

We present the electrochemical results of highly porous and interconnected carbon material by activation of graphene foam/polyvinyl alcohol-formaldehyde composite material designated as GF/PVA-F. Asymmetric supercapacitor devices were fabricated using the activated material (GF/PVA-F) and activated carbon (AC) as the positive and negative electrodes respectively. The device exhibited a maximum energy density of 42 mWh cm-2, a power density of 0.5 W cm-2 and 98% retention of its initial capacitance after 2000 cycles in an extended cell potential window of 1.8 V in 1 M Na2SO4 aqueous electrolyte. This work shows the great potential of this material for high performance energy storage application.

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

2015-01-01

348

Effect of ? irradiation on poly(vinyl alcohol) and bacterial cellulose composites used as packaging materials  

NASA Astrophysics Data System (ADS)

The aim of this paper is to present the influence of bacterial cellulose microfibrils and ?-radiation dose on poly(vinyl alcohol) (PVA)-bacterial cellulose (BC) composites. Two composite materials were obtained: the first one from PVA aqueous solution 4% and 5% wet bacterial cellulose and the second from the same PVA solution and 10% wet bacterial cellulose. In terms of PVA/dry BC ratios (w/w) for these films the ratios are 1/0.025 and 1/0.050. The obtained composite materials were characterized by infrared spectroscopy with Fourier transform (FT-IR) and UV-vis spectroscopy in order to evaluate the irradiation effect on their stability. The swelling behavior of the polymeric composites was also studied. The composite materials were compared with a film of pure PVA and a dry BC membrane.

Stoica-Guzun, Anicuta; Stroescu, Marta; Jipa, Iuliana; Dobre, Loredana; Zaharescu, Traian

2013-03-01

349

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

350

Holograms in polyvinyl alcohol photosensitized with CuCl2(2H2O)  

NASA Astrophysics Data System (ADS)

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 the concentration of a photosensitive agent were analyzed. We show there exists a correspondence between the diffraction efficiency parameter with concentration change of CuCl2(2H2O). The low toxicity of this holographic recording material as well as its peculiar behavior, photosensitivity, and ability to conduct electricity, makes it attractive for production diffractive optical elements with bio-polymers.

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

2011-06-01

351

Self-supported fibrin-polyvinyl alcohol interpenetrating polymer networks: an easily handled and rehydratable biomaterial.  

PubMed

A fibrin hydrogel at physiological concentration (5 mg/mL) was associated with polyvinyl alcohol (PVA) inside an interpenetrating polymer networks (IPN) architecture. Previously, PVA has been modified with methacrylate functions in order to cross-link it by free-radical polymerization. The fibrin network was synthesized by the enzymatic hydrolysis of fibrinogen by thrombin. The resulting self-supported materials simultaneously exhibit the properties of the fibrin hydrogel and those of the synthetic polymer network. Their storage modulus is 50-fold higher than that of the fibrin hydrogel and they are completely rehydratable. These materials are noncytotoxic toward human fibroblast and the fibrin present on the surface of PVAm-based IPNs favors cell development. PMID:24050436

Bidault, Laurent; Deneufchatel, Marie; Vancaeyzeele, Cédric; Fichet, Odile; Larreta-Garde, Véronique

2013-11-11

352

Electrospun polyvinyl-alcohol nanofibers as oral fast-dissolving delivery system of caffeine and riboflavin.  

PubMed

Fast-dissolving drug delivery systems were prepared by electrospinning using polyvinyl alcohol (PVA) as the filament-forming polymer and drug carrier. Caffeine and riboflavin were used as the model drugs. Scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) and X-ray diffraction were applied to investigate the physicochemical properties of electrospun nanofibers. The SEM images showed that nanofibers prepared from electrospinning PVA/drug aqueous solutions possessed an ultrafine morphology with an average diameter in the range of 260-370 nm. Pharmacotechnical tests showed that PVA/caffeine and PVA/riboflavin nanofibrous mats had almost the same dissolution time (about 1.5 s) and wetting time (about 4.5 s). The release measurements indicated that drugs can be released in a burst manner (caffeine to an extent of 100% and riboflavin to an extent of 40% within 60 s) from the PVA nanofibrous matrices. PMID:23201736

Li, Xiaoqiang; Kanjwal, Muzafar A; Lin, Lin; Chronakis, Ioannis S

2013-03-01

353

Ice nucleation in emulsified aqueous solutions of antifreeze protein type III and poly(vinyl alcohol).  

PubMed

Antifreeze protein (AFP) III and poly(vinyl alcohol) (PVA) are known as anti-ice nucleating agents (anti-INAs), which inhibit heterogeneous ice nucleation. However, the effectiveness of these anti-INAs in inhibiting ice nucleation in water-in-oil (W/O) emulsions, in which homogeneous ice nucleation can be experimentally simulated, is unclear. In this study, the ice nucleation temperature in emulsified solutions of AFP III, PVA, and other nonanti-INA polymers was measured, and then the nucleation rate was analyzed based on classical nucleation theory. Results showed that ice nucleation was surface-initiated and, except for PVA solutions, probably caused heterogeneously by the emulsifier, SPAN 65, at the droplet surfaces. In this nucleation mode, AFP III had no significant effect on the ice nucleation rate. In contrast, PVA exhibited ice-nucleating activity only at the droplet surfaces, suggesting that the nucleation is due to the interaction between PVA and SPAN 65. PMID:21619040

Inada, Takaaki; Koyama, Toshie; Goto, Fumitoshi; Seto, Takafumi

2011-06-23

354

[Discrimination of plasticizers and screening of phthalates in polyvinyl chloride using DART-TOF/MS].  

PubMed

A technique using a direct analysis in real time (DART) ion source coupled with time of flight/mass spectrometry (TOF/MS) was developed to discriminate plasticizers and to screen phthalates in polyvinyl chloride (PVC). In DART-TOF/MS analysis of 40 plasticizers, the protonated molecular ion, [M+H](+), was detected for most plasticizers, and the molecular weight could be easily predicted. In the analysis of PVC sheets and toys, mass spectra of plasticizers were successfully detected, and accordingly, plasticizers in PVC were easily discriminated. PVC with a phthalates content in excess of 0.1% could be screened accurately according to the DART-TOF/MS ion intensity of phthalates corresponding to the limit of detection or a suitable criterion value. DART-TOF/MS analysis is a simple and rapid technique that is suitable for the discrimination of plasticizers and for screening of phthalates in PVC. PMID:20827052

Abe, Yutaka; Yamaguchi, Miku; Mutsuga, Motoh; Hirahara, Yoshichika; Kawamura, Maiko; Kikura-Hanajiri, Ruri; Goda, Yukihiro; Kawamura, Yoko

2010-01-01

355

Influence of plasticised poly(vinyl chloride) on platelet adhesion and platelet aggregates.  

PubMed

The most widely used plasticiser for poly(vinyl chloride) (PVC) is di-(2-ethyl-hexyl) phthalate (DEHP), which is extracted in contact with blood. One approach to reducing plasticiser extraction is to incorporate the higher molecular weight plasticisers trioctyl trimellitate (TOTM) and polymeric adipate (PA). This investigation has compared the influence of these plasticisers with that of DEHP on platelet adhesion and platelet aggregate formation. PVC tubing was tested in the absence of anticoagulants and in the presence of heparin. Our results demonstrate the influence of plasticisers on platelet response and support the view that evaluation of such plasticisers should be extended from an examination of toxicological properties to a comprehensive blood compatibility assessment. PMID:2767792

Jones, C; Courtney, J M; Robertson, L M; Biggs, M S; Lowe, G D

1989-07-01

356

Study of polyvinyl alcohol nanofibrous membrane by electrospinning as a magnetic nanoparticle delivery approach  

SciTech Connect

Electrospinning technique was used to fabricate polyvinyl alcohol (PVA)-based magnetic biodegradable nanofibers. PVA solution was mixed with ferrofluid or magnetic nanoparticles (MNPs) powder and formed two individual nanofibrous membranes (PVA/ferrofluid and PVA/MNPs powder) by electrospinning. The surface morphology of the nanofibrous membrane was characterized by scanning electron microscopy and the magnetic properties were measured by vibrating sample magnetometer. Macrophages (RAW 264.7) were co-cultured with the nanofibrous membranes for 12, 24, and 48 h and exhibited good cell viability (>95%). Results showed that the PVA fibers would be degraded and the embedded Fe{sub 3}O{sub 4} nanoparticles would be released and delivered to cells.

Ger, Tzong-Rong; Huang, Hao-Ting; Hu, Keng-Shiang [Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu, Taiwan (China); Huang, Chen-Yu [Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Lai, Jun-Yang [Department of Applied Physics, National Ping Tung University of Education, Pingtung, Taiwan (China); Chen, Jiann-Yeu [Center of Nanoscience and Nanotechnology, National Chung Hsing University, Taichung, Taiwan (China); Lai, Mei-Feng, E-mail: mflai@mx.nthu.edu.tw [Institute of NanoEngineering and MicroSystems, National Tsing Hua University, Hsinchu, Taiwan (China); Department of Power Mechanical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China)

2014-05-07

357

Impedance Spectroscopy and DSC Studies of Poly(vinyl Alcohol)/silicotungstic Acid Crosslinked Composite Membranes  

NASA Astrophysics Data System (ADS)

Chemically crosslinked composite membranes consisting of poly(vinyl alcohol) (PVA) and silicotungstic acid (STA) have been prepared by solution casting method and evaluated as proton conducting polymer electrolytes. The proton conductivity of the membranes were investigated as a function of blending composition, crosslinking density and temperature. The conductivity mechanism was investigated by using Impedance spectroscopy in the region between 40 Hz and 10 MHz. Membranes were also characterized by FTIR spectroscopy to confirm the crosslinking reaction and differential scanning calorimetry (DSC) to assess the thermal stability. Membrane swelling decreased with increase in crosslinking density accompanied by improvement in mechanical properties. The proton conductivity of the membranes were of the order of 10-3 S/cm and showed similar resistance to methanol permeability than Nafion 112 under the same measurement conditions.

Anis, Arfat; Banthia, A. K.

2006-06-01

358

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

359

Structure-property relationships in Sterculia urens/polyvinyl alcohol electrospun composite nanofibres.  

PubMed

Sterculia urens (Gum Karaya) based polyvinyl alcohol (PVA) composite nanofibres have been successfully electrospun after chemical modification of S. urens to increase its solubility. The effect of deacetylated S. urens (DGK) on the morphology, structure, crystallization behaviour and thermal stability was studied for spuned fibres before and after spinning post treatment. An apparent increase in the PVA crystallinity were observed in the PVA-DGK composite nanofibres indicating S. urens induced crystallization of PVA. The pure PVA nanofibre and the nanofibres of PVA-DGK composites were introduced to post electrospinning heat treatment at 150°C for 15min. The presence of sterculia gum reduced the fibre diameter and distribution of the nanofibres due to the increased stretching of the fibres during spinning. Switching of the thermal behaviour occurs due to post spinning heat treatments. PMID:25662689

Patra, Niranjan; Martinová, Lenka; Stuchlik, Martin; ?erník, Miroslav

2015-04-20

360

Adsorption of polyvinyl alcohol from wastewater by sintered porous red mud.  

PubMed

Several types of red mud-based porous materials (RMPM) and other raw minerals via different processes were prepared and characterized using X-ray diffraction (XRD) analyses and scanning electron microscope (SEM) observations. Using the polymer sponge method, a 72% apparent porosity could be reached compared with 64% by adding a pore-forming agent. These materials were tested for their adsorption of polyvinyl alcohol (PVA) from simulated textile wastewater. The best mass ratio of RMPM to PVA solution was 50:100 with a removal maximum of 25.8% after they were in contact for 50 min. The adsorption rate and kinetics could be better described by Lagergren's pseudo-second-order model in comparison with the pseudo-first-order model. PMID:22592478

Zhang, Yihe; Chen, Wei; Lv, Guocheng; Lv, Fengzhu; Chu, Paul K; Guo, Wenmin; Cui, Baolin; Zhang, Rui; Wang, Hell

2012-01-01

361

Development of clindamycin-loaded wound dressing with polyvinyl alcohol and sodium alginate.  

PubMed

To develop a clindamycin-loaded wound dressing, cross-linked hydrogel films were prepared using freeze-thawing method with various mixtures of polyvinyl alcohol (PVA) and sodium alginate (SA). The physicochemical properties such as swelling ratio, tensile strength and elongation of hydrogels were evaluated. The drug release from this clindamycin-loaded hydrogel, in vitro protein adsorption test and in vivo wound healing observations in rats were then performed. Increased SA concentration decreased the gelation %, maximum strength and break elongation, but it resulted into an increment in the swelling ability, elasticity and thermal stability of hydrogel film. However, SA had insignificant effect on the release of clindamycin. This hydrogel improved the healing rate of artificial wounds in rats. Thus, a clindamycin-loaded wound dressing with PVA and SA hydrogel should be a candidate for wound care. PMID:19043213

Kim, Jong Oh; Choi, Jun Young; Park, Jung Kil; Kim, Jeong Hoon; Jin, Sung Giu; Chang, Sun Woo; Li, Dong Xun; Hwang, Ma-Ro; Woo, Jong Soo; Kim, Jung-Ae; Lyoo, Won Seok; Yong, Chul Soon; Choi, Han-Gon

2008-12-01

362

Changes in the optical spectra of poly(vinyl chloride) as a result of gamma irradiation  

NASA Astrophysics Data System (ADS)

In the present work, the effect of different doses of gamma rays ranging from 50 to 500 kGy on the transmission spectra and the tristimulus transmittance as well as the absorption coefficient in the range 400-700 nm of poly(vinyl chloride) (PVC) were studied by the optical transmission spectra. Variation in the group coordination in the near infrared region (700-3000 nm) were also studied. The data indicated that measurable and remarkable changes in the transmittance of the irradiated samples, as well as decrease in the tristimulus transmittance values, as compared to the unirradiated PVC sample were detected. Moreover, the irradiated samples acquire various colors depending on the radiation doses. Linear empirical formulae are estimated to determine gamma doses from the values of CIE translucency and the absorption coefficients of PVC at 550 and 650 ?m.

El-Zaher, N. A.; Osiris, W. G.

363

Low temperature magnetoresistance and magnetization studies of iron encapsulated multiwall carbon nanotube/polyvinyl chloride composites  

NASA Astrophysics Data System (ADS)

We present the experimental results of temperature dependent magnetoresistance (MR) and the magnetization studies of iron encapsulated multiwall carbon nanotube (MWCNT)/polyvinyl chloride (PVC) composites with different wt% of MWCNTs. Transmission electron microscopy characterization shows that MWCNTs are encapsulated with rod-shaped iron nanoparticles of aspect ratio of ~3. The MR behavior of 1.9 wt% MWCNT/PVC sample shows dominance of forward scattering and wave function shrinkage whereas, weak localization and electron-electron interactions explain the MR data of higher wt% samples (9.1, 16.6 and 44.4 wt%). The composites of 4.7 and 9.1 wt% exhibit ferromagnetic behavior at all temperatures with room temperature coercivities of ~1036 and 628 Oe, respectively.

Vasanthkumar, M. S.; Sameera, I.; Bhatia, Ravi; Prasad, V.; Jayanna, H. S.

2015-01-01

364

[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

365

The use of polyvinyl alcohol glutaraldehyde as solid-phase in ELISA for plague.  

PubMed

Discs of polyvinyl alcohol cross-linked with glutaraldehyde were synthesized under acid catalysis (H2SO4). Then, the antigen F1 purified from Yersinia pestis was covalently linked to this modified polymer. Afterwards, an enzyme-linked immunosorbent assay (ELISA) was established for the diagnosis of plague in rabbit and human. The best conditions for the method were achieved by using 1.3 micrograms of F1 prepared in 0.067 M phosphate buffer, pH 7.2, containing 1 M NaCl (PBS); anti-IgG peroxidase conjugate diluted 6,000 times and as a blocking agent 3% w/v skim milk in PBS. The titration of positive rabbit serum according to this procedure detected antibody concentrations up to 1:12,800 times. The present method, the conventional ELISA and passive haemagglutination assay are compared. PMID:8736090

Araujo, A M; Petribú, A T; Sales Barbosa, G H; Diniz, J R; de Almeida, A M; Mendes Azevedo, W; Malagueño, E; Carvalho Júnior, L B

1996-01-01

366

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

367

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

368

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

369

Primary processes of radiation chemical reduction of heptylviologen bromide in polyvinyl alcohol  

SciTech Connect

The primary processes of radiation chemical reduction of heptylviologen bromide in a matrix of polyvinyl alcohol were investigated by the method of pulse radiolysis. It was shown that simultaneously with the biologen radical cations, shortlived OH adducts (in the absorption spectrum a maximum at lambda /SUB max/ = 570 nm) and protonated forms (lambda /SUB max/ = 595 nm) are produced under the action of radiation. Twostep formation of viologen radical cations as a result of the interaction of heptylviologen bromide with the free electrons of the medium and with radicals formed under the action of ionizing radiation on the polymer was detected. The effective rate constant of the reaction of viologen at the second step was (1.3 + or 0.2).10/sup 2/ dm/sup 3//(mole x sec).

Kolotikin, A.S.; Krainov, I.P.; Maltsev, E.I.

1986-11-01

370

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

371

High shear homogenization of lignin to nanolignin and thermal stability of nanolignin-polyvinyl alcohol blends.  

PubMed

A new method to prepare nanolignin using a simple high shear homogenizer is presented. The kraft lignin particles with a broad distribution ranging from large micron- to nano-sized particles were completely homogenized to nanolignin particles with sizes less than 100?nm after 4?h of mechanical shearing. The (13) C nuclear magnetic resonance (NMR) and (31) P?NMR analysis showed that there were no major changes in the chemical composition between the starting kraft lignin particles and the nanolignin obtained after 4?h of mechanical treatment. The nanolignin particles did not show any change in molecular weight distribution and polydispersity compared to the original lignin particles. The nanolignin particles when used with polyvinyl alcohol (PVA) increased the thermal stability of nanolignin/PVA blends more effectively compared to the original lignin/PVA blends. PMID:25319811

Nair, Sandeep S; Sharma, Sudhir; Pu, Yunqiao; Sun, Qining; Pan, Shaobo; Zhu, J Y; Deng, Yulin; Ragauskas, Art J

2014-12-01

372

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

373

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

374

Effect of cellulose nanowhiskers on surface morphology, mechanical properties, and cell adhesion of melt-drawn polylactic Acid fibers.  

PubMed

Polylactic acid (PLA) fibers were produced with an average diameter of 11.2 (± 0.9) ?m via a melt-drawing process. The surface of the PLA fibers was coated with blends of cellulose nanowhiskers (CNWs) (65 to 95 wt %) and polyvinyl acetate (PVAc). The CNWs bound to the smooth PLA fiber surface imparted roughness, with the degree of roughness depending on the coating blend used. The fiber tensile modulus increased 45% to 7 GPa after coating with 75 wt % CNWs compared with the uncoated PLA fibers, and a significant increase in the fiber moisture absorption properties at different humidity levels was also determined. Cytocompatibility studies using NIH-3T3 mouse fibroblast cells cultured onto CNWs-coated PLA surface revealed improved cell adhesion compared with the PLA control, making this CNW surface treatment applicable for biomedical and tissue engineering applications. Initial studies also showed complete cell coverage within 2 days. PMID:24725085

Hossain, Kazi M Zakir; Hasan, Muhammad S; Boyd, Daniel; Rudd, Chris D; Ahmed, Ifty; Thielemans, Wim

2014-04-14

375

Reactivity of some sugars and sugar phosphates towards gold(III) in sodium acetate–acetic acid buffer medium  

Microsoft Academic Search

The kinetics of the oxidation of some aldoses and aldose phosphates have been studied spectrophotometrically in sodium acetate–acetic acid buffer medium at different temperatures. The reactions are first order with respect to [Au(III)] and [substrate]. Both H+ and Cl? ions retard the reaction. The reactions appear to involve different gold(III) species, viz. AuCl4?, AuCl3(OH2) and AuCl3(OH)?. The results are interpreted

Kalyan Kali Sen Gupta; Biswajit Pal; Bilkis Ara Begum

2001-01-01

376

Tetrazole acetic acid: Tautomers, conformers, and isomerization  

SciTech Connect

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{sup ?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{sup ?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{sup ?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{sup ?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{sup ?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 N{sub 2} 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 CO{sub 2} and 5-methyl-tetrazole, is proposed.

Araujo-Andrade, C. [Unidad Académica de Física de la Universidad Autónoma de Zacatecas, Zacatecas (Mexico) [Unidad Académica de Física de la Universidad Autónoma de Zacatecas, Zacatecas (Mexico); Department of Chemistry, University of Coimbra, 3004-535 Coimbra (Portugal); Reva, I., E-mail: reva@qui.uc.pt; Fausto, R. [Department of Chemistry, University of Coimbra, 3004-535 Coimbra (Portugal)] [Department of Chemistry, University of Coimbra, 3004-535 Coimbra (Portugal)

2014-02-14

377

Experimental study of the hydrothermal reactivity of organic acids and acid anions: II. Acetic acid, acetate, and valeric acid  

NASA Astrophysics Data System (ADS)

Organic acids and acid anions occur in substantial concentrations in many aqueous geologic fluids and are thought to take part in a variety of geochemical processes ranging from the transport of metals in ore-forming fluids to the formation of natural gas to serving as a metabolic energy source for microbes in subsurface habitats. The widespread occurrence of organic acids and their potential role in diverse geologic processes has led to numerous experimental studies of their thermal stability, yet there remain substantial gaps in our knowledge of the factors that control the rates and reaction pathways for the decomposition of these compounds under geologic conditions. In order to address some of these uncertainties, a series of laboratory experiments were conducted to examine the behavior of organic acids and acid anions under hydrothermal conditions in the presence of minerals. Reported here are results of experiments where aqueous solutions of acetic acid, sodium acetate, or valeric acid ( n-pentanoic acid) were heated at 325°C, 350 bars in the presence of the mineral assemblages hematite + magnetite + pyrite, pyrite + pyrrhotite + magnetite, and hematite + magnetite. The results indicate that aqueous acetic acid and acetate decompose by a combination of two reaction pathways: decarboxylation and oxidation. Both reactions are promoted by minerals, with hematite catalyzing the oxidation reaction while magnetite catalyzes decarboxylation. The oxidation reaction is much faster, so that oxidation dominates the decomposition of acetic acid and acetate when hematite is present. In contrast to previous reports that acetate decomposed more slowly than acetic acid, we found that acetate decomposed at slightly faster rates than the acid in the presence of minerals. Although longer-chain monocarboxylic acids are generally thought to decompose by decarboxylation, valeric acid appeared to decompose primarily by "deformylation" to 1-butene plus formic acid. Subsequent decomposition of 1-butene and formic acid generated a variety of short-chain (?C 4) hydrocarbons and moncarboxylic acids as well as CO 2. Valeric acid decomposition proceeded more rapidly (by a factor of 2) in the presence of hematite-magnetite-pyrite than with the other mineral assemblages, with the greater reaction rate apparently attributable to the effects of fluid chemistry. Valeric acid was observed to decompose at a substantially faster rate than acetic acid under similar conditions. The results suggest that decomposition of aqueous monocarboxylic acids may make a significant contribution to the conversion of petroleum to light hydrocarbons in natural gas and thermal fluids.

McCollom, Thomas M.; Seewald, Jeffrey S.

2003-10-01

378

Mechanical denaturation of high polymers in solutions XXIX. Stress-induced crystallization of poly(vinyl alcohol) from its aqueous solution under steady-state flow  

Microsoft Academic Search

The crystallization of poly(vinyl alcohol), derived from its aqueous solution was carried out under a steady-state flow. The effect of the rate of stirring on the crystallization and details of several phenomena observed in stirred solutions during crystallization are presented. Moreover, the structure of crystallized poly(vinyl alcohol) was studied with use of an electron microscope. Evidence is presented for a

K. Yamaura; K. Ide; S. Matsuzawa

1973-01-01

379

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

380

The Preparation of Polyvinyl Chloride-Based Thiosemicarbazide Resin and Its Selective Adsorption of Ag(I) and Au(III)  

Microsoft Academic Search

A thiosemicarbazide resin based on polyvinyl chloride (TPV) was synthesized via the reaction between polyvinyl chloride supported diethylenetriamine (PVC-DETA) and CS2\\/thiosemicarbazide. Its structure was characterized by elemental analysis and infrared spectra analysis. The adsorption properties for the single ion solutions of Cu(II), Zn(II), Cd(II), Pb(II), Hg(II), Ag(I), Au(III) and binary ion solutions containing Ag(I) or Au(III) were studied. Experimental results

Lei Guo; Chunping Liu; Zhenliang Guo; Lin Sun; Junshen Liu

2011-01-01

381

[Catamenial pneumothorax with breast cancer treated successfully by goserelin acetate].  

PubMed

A 47-year-old woman with 4 episodes of right pneumothorax related to onset of menstruation was reported. A month ago, she was undergone breast conserving resection for breast cancer. She had recurrent right pneumothorax a month later and operation was performed. Thoracoscopy revealed the presence of multiple fenestrations in the right diaphragm. Thoracoscopic partial resection of the diaphragm was performed. Histopathological findings of the lesion showed spindle cells with hemosiderosis. Immunohistochemistry showed that spindle cells were estrogen receptor (ER) positive and progesterone receptor (PgR) positive, compatible with endometriosis. She was treated by tamoxifen and goserelin acetate for breast cancer and endometriosis. Two years later, gonadotropin releasing hormone (GnRH) analogue was converted from goserelin acetate to leuprorelin acetate. She was diagnosed as having recurrence of right pneumothorax 17 months later and was treated with a chest tube. Additionally, GnRH analogue was re-converted to goserelin acetate. Since then, she has been asymptomatic free for 18 months. A catamenial pneumothorax is rare disease with difficulty of diagnosis and treatment We herein report a case of the disease that was treated successfully by goserelin acetate. PMID:19827558

Matsuura, Motoki; Fujiwara, T; Kataoka, K; Itoh, M; Ohtani, S; Higaki, K; Senoo, N

2009-10-01

382

Dodecyl acetate, a second pheromone component of the cabbage looper moth, Trichoplusia ni  

Microsoft Academic Search

Dodecyl acetate was identified as a second component of the sex pheromone ofTrichoplusia ni (Hübner). Dodecyl acetate comprised 9.6% by weight of the total pheromone [(Z)-7-dodecenyl acetate plus dodecyl acetate] extracted from glands and 7.3% by weight of the total pheromone evaporated from the surfaces of glands. Dodecyl acetate appears to function as a short-range pheromone component. Evaporation at female

Louis B. Bjostad; Lyle K. Gaston; Lesly L. Noble; J. Harvey Moyer; H. H. Shorey

1980-01-01

383

Analysis of thermal decomposition products arising from polyvinyl chloride analogs by supersonic jet/multiphoton ionization/mass spectrometry.  

PubMed

Polyvinyl chloride (PVC) and chlorinated polyvinyl chloride (CPVC) were thermally decomposed at 200-500 degrees C, and the reaction products measured by supersonic jet/multiphoton ionization/mass spectrometry. No precursor molecules of dioxins, such as chlorobenzene, were observed from PVC, although benzene was produced as one of the major components. On the other hand, a large peak corresponding to chlorobenzene was observed, when CPVC was used as a sample. These results suggest that the release of hydrogen chloride and aromatic ring formation occur efficiently and produce chlorinated aromatic hydrocarbons only when excess chlorine atoms are present in the chain of PVC. This method, which has very high selectivity is preferred for trace analysis of specific compounds such as dioxin precursors in a complex mixture. Isomer-selective analysis, e.g. detection of o-, m-, and p-dichlorobenzenes, is also demonstrated in this study. PMID:18968029

Urabe, T; Imasaka, T

2000-07-31

384

Fouling and cleaning characteristics of ultrafiltration of hydrophobic dissolved organic matter by a polyvinyl chloride hollow fiber membrane.  

PubMed

Ultrafiltration membrane fouling is a significant problem in drinking water treatment. Many researchers believe that hydrophobic natural organic matter is the main foulant. In this research, fulvic acid, tannin, and aniline were used to represent hydrophobic acid, neutral, and base, respectively, to investigate modified polyvinyl chloride ultrafiltration membrane fouling characteristics. Four kinds of cleaning methods were used in this study: flushing, backwashing, flushing and backwashing, and chemical cleaning with 0.5% sodium hydroxide. Each was performed on the three hydrophobic dissolved organic matters (acid, neutral, and base) to identify the fouling mechanisms of polyvinyl chloride ultrafiltration membrane. Results showed that hydrophobic base fouled membranes the most and hydrophobic acid the least based on cleaning difficulty. PMID:19623742

Guo, Xiaoyan; Gao, Wei; Li, Jihui; Hu, Wanli

2009-06-01

385

Crosslinked poly(vinylbenzyl chloride) with a macromolecular crosslinker for anion exchange membrane fuel cells  

NASA Astrophysics Data System (ADS)

A new material based on crosslinked poly(vinylbenzyl chloride) (PVBC) with a macromolecular crosslinker is synthesized and employed as the membrane for anion exchange membrane fuel cells (AEMFCs). PVBC is used as the hydroxide conducting polymers, while poly(vinyl acetal) (PVAc) containing dimethylamino groups plays the role as macromolecular crosslinker and the supporting matrix simultaneously. Fourier transform infrared (FT-IR) absorption spectra and X-ray photoelectron (XPS) spectra prove successful crosslinking between PVBC and PVAc. The crosslinked membrane shows hydroxide conductivity larger than 0.01 S cm-1 at room temperature, and the swelling by water at elevated temperature is suppressed. The H2/O2 AEMFC using the crosslinked membrane shows a peak power density (Pmax) of 124.7 mW cm-2 at 40 °C, and the decrease of the open circuit voltage (OCV) of the fuel cell is negligible under continuous OCV conditions for 120 h. All the results indicate that the crosslinking with a macromolecular crosslinker may be a promising strategy to fabricate anion exchange membrane for the application in the AEMFCs.

Lu, Wangting; Shao, Zhi-Gang; Zhang, Geng; Zhao, Yun; Yi, Baolian

2014-02-01

386

Specific features of spectra of cyclometalated Pt(II) and Pd(II) complexes in polyvinyl alcohol  

NASA Astrophysics Data System (ADS)

The absorption spectra and luminescent properties of ethylenediamine complexes of Pt(II) and Pd(II) with cyclometalating ligands (2-phenylpyridinate and 2-2'-thienyl)pyridinate) in polyvinyl alcohol are studied. It is ascertained that, upon an increase in temperature, the nonradiative degradation of energy in palladium complexes occurs according to the mechanism of strong vibronic coupling, whereas platinum complexes show weak vibronic coupling.

Nevdakh, M. M.; Puzyk, M. V.

2004-11-01

387

Geopolymer-Organic Polymer Composite Synthesized by the Interactions of H3PO4 with Metakaolinite Powders and Polyvinyl Alcohol  

Microsoft Academic Search

Metakaolinite (MK)-based geopolymer-polyvinyl alcohol (PVA) composite (GPC) was synthesized in the presence of aqueous phosphoric acid as an activator at room temperature. The microstructure and morphological changes of GPC were analyzed by means of X-ray diffraction (XRD), Fourier transform-infrared spectrometry (FT-IR), thermal analysis (DSC-TG), and scanning electron microscopy (SEM). XRD and SEM results showed that the amorphous phase, including C,

Tao Xu; Jing-Zhong Chen; Wei Han; Zhen Li; Gang Yu

2010-01-01

388

Particle configuration and mechanical properties of poly(vinyl chloride)\\/montmorillonite nanocomposites via in situ suspension polymerization  

Microsoft Academic Search

Poly(vinyl chloride)\\/montmorillonite (PVC\\/MMT) nanocomposites were synthesized via in situ intercalative polymerization and their microstructure, particle characteristics and mechanical properties were investigated. The montmorillonite layers were almost exfoliated into nanoscale layers and an exfoliated nanostructure was obtained. The mean particle size of the nanocomposites decreased and the degree of porosity of the particles increased with increasing organic modified montmorillonite (OMMT) content.

Fangling Gong; Meng Feng; Chungui Zhao; Shimin Zhang; Mingshu Yang

2004-01-01

389

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

390

Migration of di-(2-ethylhexylexyl)Adipate Plasticizer from Food-Grade Polyvinyl Chloride Film into Hard and Soft Cheeses  

Microsoft Academic Search

Food-grade polyvinyl chloride (PVC) film containing 28.3% di-(2-ethylhexylexyl)adipate (DEHA) plasti- cizer was used to wrap three different types of cheese (Kefalotyri, Edam, and Feta). Samples were split into two groups and stored at 5 ± 0.5°C. One group was analyzed for DEHA content at intervals between 1 and 240 h of contact (kinetic study), and a second group was cut

A. E. Goulas; K. I. Anifantaki; D. G. Kolioulis; M. G. Kontominas

2000-01-01

391

Blood response to plasticized poly(vinyl chloride): Dependence of fibrinogen adsorption on plasticizer selection and surface plasticizer level  

Microsoft Academic Search

The high level of plasticizer in plasticized poly(vinyl chloride) (PVC) ensures that plasticizer selection has an important influence on the suitability of PVC to function in blood-contacting applications. In this study, three types of plasticized PVC in sheet form, with di-(2-ethylhexyl)phthalate (DEHP), tri-(2-ethylhexyl)trimellitate (TEHTM) and n-butyryltri-n-hexyl citrate (BTHC) as plasticizer, were selected for assessment and single solute fibrinogen adsorption was

X. B. Zhao; J. M. Courtney

2003-01-01

392

Phase transfer catalysed surface modification of plasticized poly(vinyl chloride) in aqueous media to retard plasticizer migration  

Microsoft Academic Search

Plasticized poly(vinyl chloride) (PVC) sheets were surface modified by nucleophilic substitution of chlorine by azide in aqueous media under phase transfer conditions. PVC was reacted with a 40% solution of sodium azide in water using tetrabutyl ammonium bromide as the phase transfer catalyst. The reaction was conducted at temperatures ranging from 50 to 80°C for various periods of time (1–4

A. Jayakrishnan; M. C. Sunny

1996-01-01

393

Polarization-Dependent Surface-Enhanced Raman Scattering via Aligned Gold Nanorods in Poly(Vinyl Alcohol) Film  

Microsoft Academic Search

A low-cost and effective surface-enhanced Raman scattering (SERS) substrate consisting of aligned gold nanorods is obtained\\u000a by stretching the poly(vinyl alcohol) nanorods composite film doped with the probe molecule. The SERS intensity of characteristic\\u000a vibrational band of the probe is observed obviously dependent on the angle (?) between incident polarization and major axis of nanorod. The relationship between them manifests

Jun Tao; Yonghua Lu; Junxue Chen; Dawei Lu; Chunchong Chen; Pei Wang; Hai Ming

394

Stopping of ?0.2–3.4 MeV\\/amu 1H + and 4He + ions in polyvinyl formal  

Microsoft Academic Search

The stopping powers of polyvinyl formal resin for protons and alpha particles have been measured over the energy range ?(0.2–3.4)MeV\\/amu with an overall relative uncertainty of less than 2.5% using the ion beam transmission method. The obtained results are discussed in comparison to scarce experimental data from the literature and to values calculated by the SRIM-2008 computer code assuming Bragg-Kleeman’s

S. Damache; D. Moussa; S. Ouichaoui

2010-01-01

395

Polymer coating of liposomes with a modified polyvinyl alcohol and their systemic circulation and RES uptake in rats  

Microsoft Academic Search

The objective of this study was to evaluate the in vivo characteristics of liposomes coated with a polyvinyl alcohol having a long alkyl chain at the end of the molecule (PVA–R) as an injectable drug carrier for passive targeting of drugs. A fluorescence marker, cholesteryl–anthracene-9-carboxylate, was incorporated into the liposomes to detect their concentration in the plasma and organs. The

Hirofumi Takeuchi; Hiroyuki Kojima; Hiromitsu Yamamoto; Yoshiaki Kawashima

2000-01-01

396

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

397

Polyvinyl Alcohol\\/Na-Montmorillonite Nanocomposite Hydrogels Prepared by Freezing–Thawing Method: Structural, Mechanical, Thermal, and Swelling Properties  

Microsoft Academic Search

Physically crosslinked nanocomposite hydrogels based on polyvinyl alcohol (PVA) containing Na-montmorillonite were prepared by the cyclic freezing–thawing method. The primarily exfoliated morphology of prepared nanocomposite hydrogels was confirmed by X-ray diffractometry (XRD) and transmission electron microscopy (TEM) as complementary techniques. It is shown that some interactions developed between the hydroxyl groups of PVA chains and Na-montmorillonite silicate layers in the

M. Sirousazar; M. Kokabi; Z. M. Hassan; A. R. Bahramian

2012-01-01

398

Polyvinyl Alcohol \\/Na-Montmorillonite Nanocomposite Hydrogels Prepared by Freezing-Thawing Method: Structural, Mechanical, Thermal and Swelling Properties  

Microsoft Academic Search

Physically crosslinked nanocomposite hydrogels based on polyvinyl alcohol (PVA) containing Na-montmorillonite were prepared by the cyclic freezing-thawing method. The primarily exfoliated morphology of prepared nanocomposite hydrogels was confirmed by X-ray diffractometry (XRD) and transmission electron microscopy (TEM) as complementary techniques. It is shown that some interactions developed between the hydroxyl groups of PVA chains and Na-montmorillonite silicate layers in the

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

2012-01-01

399

[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

400

Cellulose acetate as solid phase in ELISA for plague.  

PubMed

Antigen from Yersinia pestis was adsorbed on cellulose acetate discs (0.5 cm of diameter) which were obtained from dialysis membrane by using a paper punch. ELISA for human plague diagnosis was carried out employing this matrix and was capable to detect amount of 1.3 microg of antigen, 3,200 times diluted positive serum using human anti-IgG conjugate diluted 1:4,000. No relevant antigen lixiviation from the cellulose acetate was observed even after washing the discs 15 times. The discs were impregnated by the coloured products from the ELISA development allowing its use in dot-ELISA. Furthermore, cellulose acetate showed a better performance than the conventional PVC plates. PMID:10656712

Barbosa, A D; Barros, F S; Callou, E Q; Almeida, A M; Araujo, A M; Azevedo, W M; Carvalho, L B

2000-01-01

401

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

402

Distribution of tunnel splittings in Mn(12) acetate.  

PubMed

In magnetic fields applied parallel to the anisotropy axis, the relaxation of the magnetization of Mn(12)-acetate measured for different sweep rates collapses onto a single scaled curve. The form of the scaling implies that the dominant symmetry-breaking process responsible for tunneling is a locally varying second-order transverse anisotropy, forbidden by tetragonal symmetry in the perfect crystal, which gives rise to a broad distribution of tunnel splittings in a real crystal of Mn(12) acetate. Different forms applied to even- and odd-numbered steps provide a clear distinction between even resonances (associated with crystal anisotropy) and odd resonances (which require a transverse magnetic field). PMID:11736425

Mertes, K M; Suzuki, Y; Sarachik, M P; Paltiel, Y; Shtrikman, H; Zeldov, E; Rumberger, E; Hendrickson, D N; Christou, G

2001-11-26

403

[Ice application for reducing pain associated with goserelin acetate injection].  

PubMed

We investigated the effectiveness of using an ice pack for reducing the pain associated with goserelin acetate injection. In this study, 39 patients with prostate cancer and 1 patient with breast cancer receiving hormonal therapy with goserelin acetate were enrolled. All patients completed a questionnaire regarding the use of ice application. We used the numerical rating scale (NRS) to assess the pain associated with injection. The NRS scores indicated that the pain was significantly less with ice application than with the usual method (p < 0.001). Further, ice application could decrease the duration of pain sensation. Ice application at the injection site is safe and effective for reducing pain. PMID:24105059

Ishii, Kaname; Nagata, Chika; Koshizaki, Eiko; Nishiuchi, Satoko

2013-10-01

404

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

405

Investigation into stability of poly(vinyl alcohol)-based Opadry® II films.  

PubMed

Poly(vinyl alcohol) (PVA)-based formulations are used for pharmaceutical tablet coating with numerous advantages. Our objective is to study the stability of PVA-based coating films in the presence of acidic additives, alkaline additives, and various common impurities typically found in tablet formulations. Opadry® II 85F was used as the model PVA-based coating formulation. The additives and impurities were incorporated into the polymer suspension prior to film casting. Control and test films were analyzed before and after exposure to 40°C/75% relative humidity. Tests included film disintegration, size-exclusion chromatography, thermal analysis, and microscopy. Under stressed conditions, acidic additives (hydrochloric acid (HCl) and ammonium bisulfate (NH(4)HSO(4))) negatively impacted Opadry® II 85F film disintegration while NaOH, formaldehyde, and peroxide did not. Absence of PVA species from the disintegration media corresponded to an increase in crystallinity of PVA for reacted films containing HCl. Films with NH(4)HSO(4) exhibited slower rate of reactivity and less elevation in melting temperature with no clear change in melting enthalpy. Acidic additives posed greater risk of compromise in disintegration of PVA-based coatings than alkaline or common impurities. The mechanism of acid-induced reactivity due to the presence of acidic salts (HCl vs. NH(4)HSO(4)) may be different. PMID:21647800

Koo, Otilia M Y; Fiske, John D; Yang, Haitao; Nikfar, Faranak; Thakur, Ajit; Scheer, Barry; Adams, Monica L

2011-06-01

406

Synthesis, characterization, optical and antimicrobial studies of polyvinyl alcohol-silver nanocomposites.  

PubMed

Silver nanoparticles (Ag NPs) were synthesized by chemical reduction of silver salt (AgNO3) through sodium borohydride. The characteristic surface plasmon resonance band located at around 400nm in the UV-Visible absorption spectrum confirmed the formation of Ag nanoparticles. Polyvinyl alcohol-silver (PVA-Ag) nanocomposite films were prepared by the casting technique. The morphology and interaction of PVA with Ag NPs were examined by transmission electron microscopy and FTIR spectroscopy. Optical studies show that PVA exhibited indirect allowed optical transition with optical energy gap of 4.8eV, which reduced to 4.45eV under addition of Ag NPs. Optical parameters such as refractive index, complex dielectric constant and their dispersions have been analyzed using Wemple and DiDomenco model. Color properties of the nanocomposites are discussed in the framework of CIE L(?)u(?)v(?) color space. The antimicrobial activity of the nanocomposite samples was tested against Gram positive bacteria (Staphylococcus aureus NCTC 7447 &Bacillus subtillis NCIB 3610), Gram negative bacteria (Escherichia coli, NTC10416 &Pseudomonas aeruginosa NCIB 9016) and fungi (Aspergillus niger Ferm - BAM C-21) using the agar diffusion technique. The antimicrobial study showed that PVA has moderate antibacterial activity against B. subtillis and the 0.04wt% Ag NPs composite sample effect was strong against S. aureus. PMID:25523046

Mahmoud, K H

2015-03-01

407

Rheological behaviour of irradiated wound dressing poly(vinyl pyrrolidone) hydrogels  

NASA Astrophysics Data System (ADS)

The use of hydrogels as biomaterials has increased lately. Poly(vinyl pyrrolidone) (PVP) is an example of polymer hydrogels applied for the synthesis of hydrogel to be used in different biomedical applications. This paper describes a study on rheological properties of PVP hydrogels obtained by gamma radiation techniques. PVP hydrogels were obtained by gamma radiation of PVP water solutions with different radiation doses. It was studied the influence of additives such as poly(ethylene glycol) (PEG), poly(ethylene oxide) (PEO) and glycerol on the rheological behaviour of the gel. The rheological behaviour of hydrogel samples was characterized by measuring the shear storage modulus ( G') under dynamic shear loading. Besides this, sterility and cytotoxicity tests were performed. The study on rheological behaviour of hydrogels showed that G' of PVP gels change according to the additive used. Glycerol increases the fluidity of the gel. The influence of PEG depends on the amount and on its molecular mass. The increase on PEG amount and molecular mass cause a decrease of G' and an increase in the crosslinking density of PVP hydrogel network. The use of high molecular weight PEO allows the increase of the elasticity of the PVP gels.

Lugão, Ademar B.; Rogero, Sizue O.; Malmonge, Sônia M.

2002-03-01

408

The polyvinyl alcohol-bacterial cellulose system as a new nanocomposite for biomedical applications.  

PubMed

Finding materials suitable for soft tissue replacement is an important aspect for medical devices design and fabrication. There is a need to develop a material that will not only display similar mechanical properties as the tissue it is replacing, but also shows improved life span, biocompatibility, nonthrombogenic, and low degree of calcification. Polyvinyl alcohol (PVA) is a hydrophilic biocompatible polymer with various characteristics desired for biomedical applications. PVA can be transformed into a solid hydrogel with good mechanical properties by physical crosslinking, using freeze-thaw cycles. Hydrophilic bacterial cellulose (BC) fibers of an average diameter of 50 nm are produced by the bacterium Acetobacter xylinum, using a fermentation process. They are used in combination with PVA to form biocompatible nanocomposites. The resulting nanocomposites possess a broad range of mechanical properties and can be made with mechanical properties similar to that of cardiovascular tissues, such as aorta and heart valve leaflets. The stress-strain properties for porcine aorta are matched by at least one type of PVA-BC nanocomposite in both the circumferential and the axial tissue directions. A PVA-BC nanocomposite with similar properties as heart valve tissue is also developed. Relaxation properties of all samples, which are important for cardiovascular applications, were also studied and found to relax at a faster rate and to a lower residual stress than the tissues they might replace. The new PVA-BC composite is a promising material for cardiovascular soft tissue replacement applications. PMID:16680717

Millon, L E; Wan, W K

2006-11-01

409

Polyvinyl alcohol electrospun nanofibers containing Ag nanoparticles used as sensors for the detection of biogenic amines.  

PubMed

Polyvinyl alcohol (PVA) electrospun nanofibers containing Ag nanoparticles (NPs) have been deposited on glass substrates. The aim of the work was to test the feasibility of this approach for the detection of biogenic amines by using either the Ag localized surface plasmon resonance quenching caused by the adsorption of amines on Ag NPs or by detecting the amines by surface enhanced Raman spectroscopy (SERS) after adsorption, from the gas phase, on the metal NPs. Two different approaches have been adopted. In the first one an ethanol/water solution containing AgNO3 was used directly in the electrospinning apparatus. In this way, a simple heat treatment of the nanofibers mat was sufficient to obtain the formation of Ag NPs inside the nanofibers and a partial cross-link of PVA. In the second procedure, the Ag NPs were deposited on PVA nanofibers by using the supersonic cluster beam deposition method, so that a beam of pure Ag NPs of controlled size was obtained. Exposure of the PVA mat to the beam produced a uniform distribution of the NPs on the nanofibers surface. Ethylendiamine vapors and volatile amines released from fresh shrimp meat were chemisorbed on the nanofibers mats. A SERS spectrum characterized by a diagnostic Ag-N stretching vibration at 230 cm(-1) was obtained. The results allow to compare the two different approaches in the detection of ammines. PMID:25627790

Marega, Carla; Maculan, Jenny; Andrea Rizzi, Gian; Saini, Roberta; Cavaliere, Emanuele; Gavioli, Luca; Cattelan, Mattia; Giallongo, Giuseppe; Marigo, Antonio; Granozzi, Gaetano

2015-02-20

410

The in vivo performance of polyvinyl alcohol macro-encapsulated islets.  

PubMed

Islet transplantation is a method for the treatment of type 1 diabetes mellitus (DM) and has been widely performed around the world. The long-term cryopreservation of islets shows many advantages in the field of islet transplantation. Previous studies have described the development of sheet-type polyvinyl alcohol (PVA) macro-encapsulated islets (MEI) to treat type 1 DM without any immunotherapy. The present study examined their beneficial effects on islet cryopreservation. PVA MEI of Wistar rats were divided into three groups of 1-day, 7-day and 30-day cryopreservation at -80 degrees C. The 30-day group showed a lower recovery rate of the islet number and impaired insulin release in comparison to the 1-day group, whereas no significant differences of the in vitro results were observed between the 1-day and 7-day groups. The MEI transplantation recipient mice in the 1-day and 7-day groups reached normoglycemia for a 4-week observation period, and the recipients in 30-day group also showed a significant decrease followed by a slightly higher non-fasting blood glucose level. These results suggest that the PVA MEI are useful for islet long-term cryopreservation, and that the use of cryopreserved PVA MEI may, therefore, be a promising modality for performing DM therapy. PMID:20149430

Qi, Zhi; Shen, Yanna; Yanai, Goichi; Yang, Kaichiang; Shirouzu, Yasumasa; Hiura, Akihito; Sumi, Shoichiro

2010-05-01

411

High-rate partial nitritation using porous poly(vinyl alcohol) sponge.  

PubMed

Poly(vinyl alcohol) (PVA) has been utilized as a support material for the immobilization of nitrifying bacteria without the comprehensive survey of partial nitritation. In the present study, the activities of nitrifiers and the maximum nitrogen conversion rate of partial nitritation with PVA sponge-cubes were specified according to different conditions. The selective enrichment of ammonia-oxidizing bacteria (AOB) on PVA sponge-cubes was achieved by the competition between AOB and nitrite-oxidizing bacteria for dissolved oxygen. The efficiency of ammonia oxidation was proportional to the concentration of HCO3 (-) with the molar ratio of HCO3 (-)-C/NH4 (+)-N = 1.91 and a half of the ratio was applied to the further experiments to ensure stable partial nitritation. The maximum nitrogen conversion rate of partial nitritation was dependent on the volume, not the size of sponge-cubes. The partial nitritation showed the superior rate performance of 3.09 kg N/m(3) day with the packing ratio of 32 % of 5 × 5 × 5 mm(3) PVA sponge-cubes. PMID:24297159

Bae, Hyokwan; Yang, Heejeong; Chung, Yun-Chul; Yoo, Young Je; Lee, Seockheon

2014-06-01

412

Effect of polyvinyl alcohol on rare earths (Gd and Tb) separation by extraction resin.  

PubMed

Small amounts of polyvinyl alcohol (PVA; 0.5-1.5 wt.%) added to extraction resin was synthesized by suspension polymerization. Their effects on the separation of rare earths (RE) were then investigated by conducting a relative comparison with the performance of pure extraction resin. The supporter and extractant of extraction resin were styrene-divinyl benzene copolymer and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]), respectively. The size of PVA added extraction resin was reduced by 40% particle size of pure extraction resin. Furthermore, a higher level of PVA addition, shorter effluent range and smaller resolution values were shown in the extraction. In constant PVA added extraction resin, more diluted effluent concentration, longer effluent range and bigger resolution values were shown in the extraction. This could be the result of the bonding force between the rare earths and the extraction resin due to the nature of the interaction between the OH(-) group in PVA and the OH(-) group in extractants such as HEH[EHP]. Thus, the bonding force between the RE and extractants was determined by the level of PVA in the resins and the acidity of the effluent solution became another important factor in the extraction performance of the rare earths. As a result, the optimal level of PVA addition and the concentration of effluent for RE (Gd and Tb) separation were determined to be 0.5 wt.% of PVA and 0.05 M HCl of effluent, respectively. PMID:18970417

Kim, Joon-Seok; Han, Choon; Wee, Jung-Ho; Kim, Joon-Soo

2006-01-15

413

Toward "strong" green nanocomposites: polyvinyl alcohol reinforced with extremely oriented cellulose whiskers.  

PubMed

To exploit the maximum potential of cellulose whiskers (CWs), we report here for the first time the successful fabrication of nanocomposites reinforced with highly oriented CWs in a polymer matrix. The nanocomposites were prepared using polyvinyl alcohol (PVA) and a colloidal suspension of cotton-derived CWs. The macroscopically homogeneous PVA-CW suspensions were extruded into cold methanol to form gel fibers followed by a hot drawing. Compared to the neat PVA fiber, the as-spun fiber containing a small amount of CWs (5 wt % of solid PVA) showed higher drawability, leading to an extremely high orientation of CWs with the matrix PVA. The stress-transfer mechanism, a prime determining factor for high mechanical properties of nanocomposites, was studied by X-ray diffraction. The stress on the incorporated CWs was monitored by applying an in situ nondestructive load to the composite fibers. The applied stress to the whole sample was found to be effectively transferred to the CWs inside the composites, suggesting strong interfacial bonding between the filler and the matrix. Effective stress transfer to the oriented whiskers resulted in outstanding enhancement in mechanical properties of the nanocomposites. PMID:21294568

Jalal Uddin, Ahmed; Araki, Jun; Gotoh, Yasuo

2011-03-14

414

Photo-responsive interpenetrating network beads of alginate/polyvinyl alcohol-coumarin conjugate.  

PubMed

Interpenetrating network (IPN) beads composed of alginate and poly(vinyl alcohol)-epoxypropoxy coumarin (PVA-EPC) conjugate were prepared by dropping the mixture solution into CaCl2 solution under UV irradiation (? = 365 nm). EPC residues of PVA-EPC could readily be dimerized by ? = 365 nm and de-dimerized by ?= 254 nm even in the presence of alginate. In addition, the viscosity of the mixture solution increased with the time of UV irradiation due to the photo-dimerization. The percentage release in 360 min of FITC-dextran loaded in the beads, which were prepared using the mixture solutions of which alginate/PVA-EPC concentrations were 0.5%/0.5%, 0.5%/1%, and 0.5%/2.5%, were about 2%, 11%, and 5%, respectively. Interestingly, in case of beads prepared using the mixture solution of which alginate/PVA-EPC concentration was 0.5%/2.5%, the release was a little but significantly promoted by the irradiation of ?= 254 nm. PMID:22713091

Seo, Seung Ree; Kim, Jin-Chul

2013-12-01

415

Poly(vinyl alcohol)/cellulose nanowhiskers nanocomposite hydrogels for potential wound dressings.  

PubMed

Polyvinyl alcohol (PVA)/cellulose nanowhisker (CNW) nanocomposite hydrogels to be used for wound dressing were obtained by freezing-thawing technique and characterized by means of morphological, physical, thermal, mechanical, barrier and antimicrobial properties. First, cellulose nanowhiskers were obtained by the acid hydrolysis of commercial crystalline microcellulose (MCC) and characterized by its size, shape, morphological, structural and thermal properties. Then, PVA/CNW nanocomposites with several CNW contents (0, 1, 3, 5 and 7wt.%) were obtained. Morphological, thermal, chemical and physical characterization of the PVA/CNW nanocomposite hydrogels was carried out. It was found that the addition of CNW to the hydrogel allows controlling the pore morphology of the samples. On the other hand, the transparency of the samples was maintained, the thermal stability was increased, the mechanical properties were improved and the water vapor transmission rate was in the range of wound dressing applications after CNW incorporation inside the PVA hydrogel matrix. The evaluation of microbial penetration showed that the prepared hydrogels can be considered as a good barrier against different microorganisms. All obtained results indicate that the PVA/CNW materials are promising to be used as wound dressing. PMID:24268233

Gonzalez, Jimena S; Ludueña, Leandro N; Ponce, Alejandra; Alvarez, Vera A

2014-01-01

416

Evaluation of hemocompatibility and endothelialization of hybrid poly(vinyl alcohol) (PVA)/gelatin polymer films.  

PubMed

Engineered grafts are still needed for small diameter blood vessels reconstruction. Ideal materials would prevent thrombosis and intimal hyperplasia by displaying hemocompatibility and mechanical properties close to those of native vessels. In this study, poly(vinyl alcohol) (PVA)/gelatin blends were investigated as a potential vascular support scaffold. We modified a chemically crosslinked PVA hydrogel by incorporation of gelatin to improve endothelial cell attachment with a single-step method. A series of crosslinked PVA/gelatin films with specific ratios set at 100:0, 99:1, 95:5, and 90:10 (w/w) were prepared and their mechanical properties were examined by uniaxial tensile testing. Tubes, obtained from sutured films, were found highly compliant (3.1-4.6%) and exhibited sufficient mechanical strength to sustain hemodynamic strains. PVA-based hydrogels maintained low level of platelet adhesion and low thrombogenic potential. Endothelial cell adhesion and proliferation were drastically improved on PVA/gelatin films with a feed gelatin content as low as 1% (w/w), leading to the formation of a confluent endothelium. Hydrogels with higher gelatin content did not sustain complete endothelialization because of modifications of the film surface, including phase segregation and formation of microdomains. Thus, PVA/gelatin (99:1, w/w) hydrogels appear as promising materials for the design of endothelialized vascular materials with long-term patency. PMID:23846987

Ino, Julia M; Sju, Ervi; Ollivier, Véronique; Yim, Evelyn K F; Letourneur, Didier; Le Visage, Catherine

2013-11-01

417

Effect of polyvinyl alcohol matrices on the structural and spectroscopic studies of CdSe nanoparticles  

NASA Astrophysics Data System (ADS)

In this work, CdSe and polyvinyl alcohol (PVA)-capped CdSe nanoparticle were prepared using a one-step solution growth technique. The experimental results from transmission electron microscopy showed that the nanoparticles were well dispersed and uniform in shape with diameter of about 95 and 25 nm for CdSe and PVA-capped CdSe, respectively. X-ray diffraction results showed that, the crystallinity of PVA largely decreased after capping with CdSe. The infrared absorption spectra were measured in the range (4000-200 cm -1). The shift of the OH band toward higher frequency indicates the degradation of the hydrogen bond between the polymer chains. The change of the intensity of the carbonyl stretch band at 1700 cm -1 indicates the electrostatic interaction between CdSe and the oxygen of carbonyl group. The optical band gap was calculated from the electronic spectra and correlated with the particle size of the capped CdSe.

Seoudi, R.; Abd El Mongy, S.; Shabaka, A. A.

2008-05-01

418

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

419

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

420

Electrospun novel super-absorbent based on polysaccharide-polyvinyl alcohol-montmorillonite clay nanocomposites.  

PubMed

A novel super-absorbent material was fabricated by electrospinning the natural polysaccharide pullulan (PULL) with polyvinyl alcohol (PVA) and montmorillonite (MMT) clay to form nonwoven webs, which were then heat treated. Transmission electron microscopy (TEM) micrographs, X-ray diffraction (XRD) patterns, and Fourier transform infrared (FTIR) analysis of the novel super-absorbent nanofibers suggest the coexistence of PULL, PVA, and MMT through the exfoliation of MMT layers in the super-absorbent nanofiber composite. The heat-treated PULL/PVA/MMT webs loaded with 5 wt% MMT electrospun nanofibers exhibited a water absorbency of 143.42gg(-1) in distilled water and a water absorbency of 39.75gg(-1) in a 0.9 wt% NaCl solution. Under extremely dry conditions, the PULL/PVA/MMT webs exhibited the ability to retain 43% distilled water and 38% saline water after being exposed to the atmosphere for one week. The heat treatment improved the crystallinity of the electrospun PULL/PVA/MMT super-absorbent webs and thus made the webs highly stable in aqueous environments. Overall, the addition of MMT resulted in improved thermal stability and mechanical properties and increased the water absorbency of the PULL/PVA/MMT composite. PMID:25439870

Islam, Md Shahidul; Rahaman, Md Saifur; Yeum, Jeong Hyun

2015-01-22

421

Arterial Distribution of Calibrated Tris-Acryl Gelatin and Polyvinyl Alcohol Embolization Microspheres in Sheep Uterus  

SciTech Connect

The purpose of this study was to compare, after embolization, the distribution in the uterine arterial vasculature of tris-acryl gelatin microspheres (TGMS) and polyvinyl alcohol microspheres (PVAMS). A limited bilateral uterine artery embolization was performed in six adult sheep under fluoroscopic control by injecting in each uterine artery 0.25 ml of 500- to 700-{mu}m TGMS of PVAMS suspended in 50/50 saline/contrast medium. Sacrifices were performed 1 week after embolization and uteri were analyzed histologically. The number and size of microspheres and vessels were measured, as well as the histological location according to a classification in four zones of the uterus. One hundred sixty-five vessels (69 vessels occluded with TGMS and 96 vessels occluded with PVAMS) were measured. The size of the occluded vessels decreased significantly from proximal to distal zones of the uterine vasculature (P < 0.0001). The location of TGMS and PVAMS within the vasculature was significantly different (P < 0.0001) since PVAMS blocked significantly more distally than TGMS. Deformation of the microspheres within the tissue was greater for PVAMS (18.0% {+-} 12.3%) than for TGMS (8.7% {+-} 9.2%) (P < 0.0001). In conclusion, PVAMS have a more distal distribution in the sheep uterine vasculature, compared to TGMS. Such differences in partition, already described in the kidney embolization model, can ultimately explain the different clinical outcome reported with these two types of microspheres in uterine fibroid embolization.

Laurent, Alexandre, E-mail: alex.laurent@lrb.ap-hop-paris.f [Lariboisiere Hospital, AP-HP, Department of Interventional Neuroradiology (France); Wassef, Michel; Namur, Julien; Ghegediban, Homayra [Lariboisiere Hospital, AP-HP, Department of Pathology (France); Pelage, Jean-Pierre [Ambroise Pare Hospital, Department of Vascular Interventional Radiology (France)

2010-10-15

422

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

423

A poly(vinyl alcohol)/sodium alginate blend monolith with nanoscale porous structure  

PubMed Central

A stimuli-responsive poly(vinyl alcohol) (PVA)/sodium alginate (SA) blend monolith with nanoscale porous (mesoporous) structure is successfully fabricated by thermally impacted non-solvent induced phase separation (TINIPS) method. The PVA/SA blend monolith with different SA contents is conveniently fabricated in an aqueous methanol without any templates. The solvent suitable for the fabrication of the present blend monolith by TINIPS is different with that of the PVA monolith. The nanostructural control of the blend monolith is readily achieved by optimizing the fabrication conditions. Brunauer Emmett Teller measurement shows that the obtained blend monolith has a large surface area. Pore size distribution plot for the blend monolith obtained by the non-local density functional theory method reveals the existence of the nanoscale porous structure. Fourier transform infrared analysis reveals the strong interactions between PVA and SA. The pH-responsive property of the blend monolith is investigated on the basis of swelling ratio in different pH solutions. The present blend monolith of biocompatible and biodegradable PVA and SA with nanoscale porous structure has large potential for applications in biomedical and environmental fields. PMID:24093494

2013-01-01

424

Dielectric relaxation and alternating current conductivity of lanthanum, gadolinium, and erbium-polyvinyl alcohol doped films  

PubMed Central

Fourier transform infrared (FTIR) spectrum dielectric constant, ??, loss tangent, tan(?), electric modulus, M*, and ac conductivity, ?ac, of pure polyvinyl alcohol (PVA) as well as La-, Gd-, and Er-PVA doped samples have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 300–450?K and 1?kHz–4?MHz, respectively. FTIR measurements reveal that La3+, Gd3+, and Er3+ ions form complex configuration within PVA structure. Two relaxation processes, namely, ? and ? were observed in pure PVA sample. The first process is due to the interfacial or Maxwell-Wagner-Sillers polarization. The second one is related to the micro-Brownian motion of the main chains. For doped PVA samples, ?-relaxation process splits into ?a and ?c. This splitting is due to the segmental motion in the amorphous (?a) and crystalline (?c) phases of PVA matrix. Electric modulus analysis was discussed to understand the mechanism of the electrical transport process. The behavior of ac conductivity for all PVA samples indicates that the conduction mechanism is correlated barrier hopping. PMID:22933826

Hanafy, Taha A.

2012-01-01

425

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

426

Effect of Process Parameters on Particle Removal Efficiency in Poly(vinyl alcohol) Brush Scrubber Cleaning  

NASA Astrophysics Data System (ADS)

Wafer cleaning is one of the most critical processes in the semiconductor device manufacturing. Poly(vinyl alcohol) (PVA) brush scrubber cleaning is much attractive when compared with traditional wet-batch cleaning which causes the cross-contamination among the wafers in a bath and environmental issues with huge amount of chemical and deionized water (DIW) usages. The mechanical forces generated from PVA brush contact can remove the particles on a wafer surface under low concentration of chemical solution without cross-contamination. In this research, we monitored the change of the dynamic forces including normal and friction force generated by PVA brush contacts during cleaning process, and also investigated the effects of scrubbing conditions of PVA brush overlap and velocity, and the surface tension (low- or high-hydrophilic) of the wafer on the particle removal efficiency. The results show that the driving mechanism to remove the particle on a wafer surface can be changed by the PVA brush overlap and velocity condition such as the hydrodynamic drag force in the brush soft contact condition and friction force in the brush hard contact condition. The particle removal efficiency is higher under the low-hydrophilic surface having a low surface tension compared to high-hydrophilic surface.

An, Joonho; Lee, Hyunseop; Kim, Hyoungjae; Jeong, Haedo

2012-02-01

427

Modulation of drug release kinetics from hydroxypropyl methyl cellulose matrix tablets using polyvinyl pyrrolidone.  

PubMed

Hydrophilic matrix tablets are widely used to extend the release of a broad range of pharmaceutically active materials. The mechanism and kinetics of drug release are dependent on the solubility of the active moiety and the swelling and erosion properties of the polymer, with water soluble compounds released predominantly by diffusion. The swelling and erosion properties of hydroxypropyl methyl cellulose (HPMC), typically lead to a first order release rate for water soluble compounds as opposed to the more desirable zero-order kinetics. In addition, for compounds with differences in regional absorption within the gastrointestinal tract a dosage form with a bi-modal release profile may be required, which is difficult to achieve with a simple dosage form. The following paper presents a simple, cost effective and elegant solution for achieving a range of predictable release profiles from linear to bi-modal for a water soluble drug (caffeine) from HPMC matrices, through the inclusion of polyvinyl pyrrolidone (PVP). Mechanistic studies using gel rheology, excipient dissolution and near-infrared microscopy (NIR) microscopy are presented which show that the modulation of drug release kinetics is mediated through a reduction in HPMC viscosity in the presence of a critical concentration of PVP, which leads to a break-up of the extended release tablet. A validated mathematical model is also presented which allows drug release profiles to be reliably predicted based on the initial HPMC and PVP content in the tablet. PMID:17306477

Hardy, Ian J; Windberg-Baarup, Anne; Neri, Claudia; Byway, Paul V; Booth, Steven W; Fitzpatrick, Shaun

2007-06-01

428

Dynamic simulation and finite element analysis of the human mandible injury protected by polyvinyl alcohol sponge.  

PubMed

There have been intensive efforts to find a suitable kinetic energy absorbing material for helmet and bulletproof vest design. Polyvinyl alcohol (PVA) sponge is currently in extensive use as scaffolding material for tissue engineering applications. PVA can also be employed instead of commonly use kinetic energy absorbing materials to increase the kinetic energy absorption capacity of current helmet and bulletproof vest materials owing to its excellent mechanical properties. In this study, a combined hexahedral finite element (FE) model is established to determine the potential protection ability of PVA sponge in controlling the level of injury for gunshot wounds to the human mandible. Digital computed tomography data for the human mandible are used to establish a three-dimensional FE model of the human mandible. The mechanism by which a gunshot injures the protected mandible by PVA sponge is dynamically simulated using the LS-DYNA code under two different shot angles. The stress distributions in different parts of the mandible and sponge after injury are also simulated. The modeling results regardless of shot angle reveal that the substantial amount of kinetic energy of the steel ball (67%) is absorbed by the PVA sponge and, consequently, injury severity of the mandible is significantly decreased. The highest energy loss (170 J) is observed for the impact at entry angle of 70°. The results suggest the application of the PVA sponge as an alternative reinforcement material in helmet and bulletproof vest design to absorb most of the impact energy and reduce the transmitted load. PMID:25063160

Karimi, Alireza; Navidbakhsh, Mahdi; Razaghi, Reza

2014-09-01

429

Radiation-induced color bleaching of methyl red in polyvinyl butyral film dosimeter  

NASA Astrophysics Data System (ADS)

Radio-chromic film based on polyvinyl butyral (PVB) containing different concentrations of methyl red (MR) dye for 0.125, 0.25 and 0.5 mM has been introduced as high dose dosimeter. The dosimeters were irradiated with gamma ray from 60Co source at doses from 5 to 150 kGy. UV/vis spectrophotometry was used to investigate the optical density of unirradiated and irradiated films in terms of absorbance at 497 nm. The dose sensitivity of MR-PVB film dosimeter increases strongly with increase of absorbed dose as well as increase of concentrations of MR dye. The effects of irradiation temperature, relative humidity, dose rate and the stability of the response of the films after irradiation were investigated and found that these films could be used as routine dosimeter in industrial radiation processing. The useful dose range of developed MR-PVB film dosimeters is in the range of 5-100 kGy.

Al Zahrany, Awad A.; Rabaeh, Khalid A.; Basfar, Ahmed A.

2011-11-01

430

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

431

Mechanical properties and in vitro characterization of polyvinyl alcohol-nano-silver hydrogel wound dressings  

PubMed Central

Polyvinyl alcohol (PVA) hydrogels are materials for potential use in burn healing. Silver nanoparticles can be synthesized within PVA hydrogels giving antimicrobial hydrogels. Hydrogels have to be swollen prior to their application, and the common medium available for that in hospitals is saline solution, but the hydrogel could also take up some of the wound's fluid. This work developed gamma-irradiated PVA/nano-Ag hydrogels for potential use in burn dressing applications. Silver nitrate (AgNO3) was used as nano-Ag precursor agent. Saline solution, phosphate-buffered solution (PBS) pH 7.4 and solution pH 4.0 were used as swelling media. Microstructural evaluation revealed an effect of the nanoparticles on PVA crystallization. The swelling of the PVA-Ag samples in solution pH 4.0 was low, as was their silver delivery, compared with the equivalent samples swollen in the other media. The highest swelling and silver delivery were related to samples prepared with 0.50% AgNO3, and they also presented lower strength in PBS pH 7.4 and solution pH 4.0. Both PVA-Ag samples were also non-toxic and presented antimicrobial activity, confirming that 0.25% AgNO3 concentration is sufficient to establish an antimicrobial effect. Both PVA-Ag samples presented suitable mechanical and swelling properties in all media, representative of potential burn site conditions. PMID:24501677

Oliveira, R. N.; Rouzé, R.; Quilty, B.; Alves, G. G.; Soares, G. D. A.; Thiré, R. M. S. M.; McGuinness, G. B.

2014-01-01

432

Silver polyvinyl pyrrolidone nanoparticles exhibit a capsular polysaccharide influenced bactericidal effect against Streptococcus pneumoniae  

PubMed Central

Streptococcus pneumoniae remains a leading cause of morbidity and mortality worldwide. The highly adaptive nature of S. pneumoniae exemplifies the need for next generation antimicrobials designed to avoid high level resistance. Metal based nanomaterials fit this criterion. Our study examined the antimicrobial activity of gold nanospheres, silver coated polyvinyl pyrrolidone (AgPVP), and titanium dioxide (TiO2) against various serotypes of S. pneumoniae. Twenty nanometer spherical AgPVP demonstrated the highest level of killing among the tested materials. AgPVP (0.6 mg/mL) was able to kill pneumococcal serotypes 2, 3, 4, and 19F within 4 h of exposure. Detailed analysis of cultures during exposure to AgPVP showed that both the metal ions and the solid nanoparticles participate in the killing of the pneumococcus. The bactericidal effect of AgPVP was lessened in the absence of the pneumococcal capsular polysaccharide. Capsule negative strains, JD908 and RX1, were only susceptible to AgPVP at concentrations at least 33% higher than their respective capsule expressing counterparts. These findings suggest that mechanisms of killing used by nanomaterials are not serotype dependent and that the capsular polysaccharide participates in the inhibition. In the near future these mechanisms will be examined as targets for novel antimicrobials. PMID:25520713

Bibbs, Ronda K.; Harris, Rhonda D.; Peoples, Veolanda A.; Barnett, Cleon; Singh, Shree R.; Dennis, Vida A.; Coats, Mamie T.

2014-01-01

433

The molecular interfacial structure and plasticizer migration behavior of "green" plasticized poly(vinyl chloride).  

PubMed

Tributyl acetyl citrate (TBAC), a widely-used "green" plasticizer, has been extensively applied in products for daily use. In this paper, a variety of analytical tools including sum frequency generation vibrational spectroscopy (SFG), coherent anti-Stokes Raman spectroscopy (CARS), contact angle goniometry (CA), and Fourier transform infrared spectroscopy (FTIR) were applied together to investigate the molecular structures of TBAC plasticized poly(vinyl chloride) (PVC) and the migration behavior of TBAC from PVC-TBAC mixtures into water. We comprehensively examine the effects of oxygen and argon plasma treatments on the surface structures of PVC-TBAC thin films containing various bulk percentages of plasticizers and the leaching behavior of TBAC into water. It was found that TBAC is a relatively stable PVC plasticizer compared to traditional non-covalent plasticizers but is also surface active. Oxygen plasma treatment increased the hydrophilicity of TBAC-PVC surfaces, but did not enhance TBAC leaching. However, argon plasma treatment greatly enhanced the leaching of TBAC molecules from PVC plastics to water. Based on our observations, we believe that oxygen plasma treatment could be applied to TBAC plasticized PVC products to enhance surface hydrophilicity for improving the biocompatibility and antibacterial properties of PVC products. The structural information obtained in this study will ultimately facilitate a molecular level understanding of plasticized polymers, aiding in the design of PVC materials with improved properties. PMID:25579625

Zhang, Xiaoxian; Li, Yaoxin; Hankett, Jeanne M; Chen, Zhan

2015-01-28

434

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

435

pH sensitivity of emeraldine salt polyaniline and poly(vinyl butyral) blend  

NASA Astrophysics Data System (ADS)

pH sensitivity of emeraldine salt polyaniline (ES-PANI) and poly(vinyl butyral) (PVB) blend film was investigated. This blend film can be used as a pH sensing element in new-type pH sensors to replace traditional instruments based on fragile glass electrodes for pH measurement of water in aquaculture farming. Structural and optical characteristic of PANI were studied by Fourier transform infrared spectroscopy (FTIR) and ultraviolet visible spectroscopy (UV–vis). Electrical characterization of ES-PANI:PVB blend films versus pH was performed with chemiresistors fabricated by micro-lithography. A ES-PANI:PVB layer was drop-coated on comb-shaped platinum electrodes patterned on SiO2/Si substrates. Scanning electron microscope (SEM) and optical microscope were used to investigate morphology of the fabricated platinum electrodes and the coated polymer blend films. I–V measurements of the polymer-coated chemiresistors were performed at very low relative humidity after the polymer films were exposed to pH 1–8. The results showed that logarithm of electrical resistance of the ES-PANI:PVB films increased almost linearly as pH increased from 1 to 8. The initial results showed that the PANI blend-coated chemiresistors can be used as pH sensors for water quality monitoring.

Duyen Nguyen, Hoa; Nguyen, Thi Ha; Hoang, Ngoc Vu; Ngan Le, Nguyen; Nhien Nguyen, Thi Ngoc; Chanh Tin Doan, Duc; Chien Dang, Mau

2014-12-01

436

Pressure dependence of the miscibility of poly(vinyl methyl ether) and polystyrene: Theoretical representation  

NASA Astrophysics Data System (ADS)

The present calculations were performed on the basis of the Sanchez-Lacombe-Balasz lattice fluid theory. The two system specific parameters ?12* and ??* required for that purpose have been obtained from the spinodal temperatures measured (SANS) for mixtures of poly(vinyl methyl ether) (PVME) and deuterated polystyrenes (d-PS) by Schwahn and coworkers. The experimental data reported for atmospheric pressure and six representatives of the present system are well described theoretically, where ?12* does not depend on molar mass and ??* decreases only slightly as the chain length of d-PS is raised. The measured pressure influences on the spinodal conditions correspond to an approximately linear reduction of ??* with increasing P; this observation should reflect the volume changes associated with the formation of specific interactions. According to the present calculations the critical composition shifts markedly towards pure PVME as P is raised. Since experimental data are commonly expressed in terms of the Flory-Huggins theory, the current results were also translated into Flory-Huggins interaction parameters and evaluated with respect to the contributions of enthalpy and of entropy. The agreement between experimental information and that calculated from the Sanchez-Lacombe-Balasz lattice fluid theory is reasonable.

An, Lijia; Horst, Roland; Wolf, B. A.

1997-08-01

437

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.

438

Fabrication and characterization of porous alginate/polyvinyl alcohol hybrid scaffolds for 3D cell culture.  

PubMed

Porous alginate/polyvinyl alcohol (PVA) hybrid scaffolds as bioartificial cell scaffolds were fabricated to improve cell compatibility as well as flexibility of the scaffolds. The alginate/PVA hybrid scaffolds with different PVA compositions up to 50 wt% were fabricated by a modified freeze-drying method including the physical cross-linking of PVA and the following chemical cross-linking of alginate. The prepared alginate/PVA hybrid scaffolds were characterized by morphology observations using scanning electron microscopy (SEM), the measurements of porosity and average pore sizes and the measurements of compressive strength and modulus. The scaffolds exhibited highly porous, open-cellular pore structures with almost the same surface and cross-sectional porosities (total porosities about 85%, regardless of PVA composition) and the pore sizes from about 290 microm to about 190 microm with increasing PVA composition. The alginate/PVA hybrid scaffolds were more soft and elastic than the control alginate scaffold without significant changes of mechanical strength. The scaffolds were examined for their in vitro cell compatibility by the culture of chondrocytes (human chondrocyte cell line) in the scaffolds and the following analyses by MTT assay and SEM observation. It was observed that the alginate/PVA scaffolds had better cell adhesion and faster growth than the control alginate scaffold. It seems that 30 wt% addition of PVA to alginate in the fabrication of the hybrid scaffolds is desirable for improving their flexibility and cell compatibility. PMID:16128229

Cho, Sang Ho; Oh, Se Heang; Lee, Jin Ho

2005-01-01

439

Composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose for drug controlled release.  

PubMed

Mono and multilayer composite films of poly(vinyl alcohol)-chitosan-bacterial cellulose (PVA/chitosan/BC) have been prepared to achieve controlled release of ibuprofen sodium salt (IbuNa) as model drug. The composite films have been characterized by Fourier transformed infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Surface morphology was investigated by scanning electron microscopy (SEM). Equilibrium swelling was measured in water at two different pH values and in vitro release of IbuNa in pH 1.2 and pH 7.4 media was studied. The release experiments revealed that drug release is pH sensitive. The release kinetics of IbuNa could be described by the Fickian model of diffusion with a good agreement. The IbuNa release rate was decreasing for all the films as the BC concentration was increased in the films composition, the decrease being higher for the multilayer films. PMID:24769089

Pavaloiu, Ramona-Daniela; Stoica-Guzun, Anicuta; Stroescu, Marta; Jinga, Sorin Ion; Dobre, Tanase

2014-07-01

440

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

441

Plasticized Poly(vinyl chloride)-Based Photonic Crystal for Ion Sensing.  

PubMed

In this study, we, for the first time, developed a plasticized poly(vinyl chloride) (PVC)-based two-dimensional photonic crystal (2D-PhC) optical sensor using nanoimprint lithography (NIL), which can perform highly sensitive, fast, and selective ion sensing based on ion extraction. Concerning the principle of response, present plasticized PVC-based PhC works as a waveguide and a grating. Incident light was guided in the bulk of plasticized PVC and, then, guided light of a specific wavelength was diffracted by a periodic nanostructure. The guided and diffracted light intensity changes of PVC-based PhCs possessing various thicknesses were monitored at 580 nm; then, we found that the 0.35 ?m-thick PhC film exhibited the highest diffraction intensity. For the ion-sensing application, potassium-selective sensing elements involving potassium ionophore and lipophilic dye were dissolved in a plasticized PVC-based PhC, and the K(+)-selective response was successfully observed by monitoring the diffracted peak intensity change. The present 2D-PhC optical sensor exhibited a fast response within 5 s (95% response time) due to the use of thin film, and sensitivity was 20 times higher than that of a PVC plane-film optical sensor, due to efficient collection of diffracted light by employing a periodic nanostructure of the photonic crystal. PMID:25397688

Aki, Shoma; Endo, Tatsuro; Sueyoshi, Kenji; Hisamoto, Hideaki

2014-12-16

442

Formation and fluidity measurement of supported lipid bilayer on polyvinyl chloride membrane  

SciTech Connect

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 SiO{sub 2}/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 SiO{sub 2}/Si, which had little immobile fraction.

Kobayashi, Takuji, E-mail: kobayashi-t@int.ee.tut.ac.jp; Kono, Akiteru, E-mail: kobayashi-t@int.ee.tut.ac.jp; Sawada, Kazuaki [Department of Electrical and Electronic Information Engineering, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, 441-8580 (Japan); Futagawa, Masato [Department of Electrical and Electronic Information Engineering and Head Office for the Tailor-Made and Baton-Zone Graduate Course, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, 441-8580 (Japan); Tero, Ryugo, E-mail: tero@tut.jp [Electronics-Inspired Interdisciplinary Research Institute and Department of Environmental and Life Sciences, Toyohashi University of Technology, 1-1 Hibarigaoka Tempaku-cho, Toyohashi, 441-8580 (Japan)

2014-02-20

443

Properties and performance of sulfide-substituted plasticized poly(vinyl chloride) as a biomaterial.  

PubMed

Plasticized poly(vinyl chloride) (PVC) was surface modified by nucleophilic substitution of the chlorine atoms of PVC by sulfide ions in aqueous media in the presence of a phase-transfer catalyst (PTC) to make it migration resistant. The modified PVC was sterilized by steam autoclaving and gamma radiation and subjected to plasticizer extraction in an extraction medium such as hexane. Virtually no plasticizer migrated out of modified PVC into the medium even after prolonged incubation for 30 d. The properties of the modified surface were evaluated by contact angle measurements, scanning electron microscopy (SEM), cell-culture studies, hemolysis assay, and whole-blood clotting time measurements. The mechanical properties of modified sheets were evaluated by measurements of tensile strength and strain at break after subjecting the specimens to different modes of sterilization. The modified PVC surface showed enhanced wettability and was found to be non-hemolytic and non-cytotoxic. Whole-blood clotting profiles of unmodified and modified PVC were virtually the same. Modification imparted slight yellow color to the material. Surface modification resulted in an 8% decrease in the ultimate stress and 28% decrease in the strain at break values. The sulfide-substituted PVC was found to be blood compatible and would be useful in applications such as tubing for transfusion, dialysis etc., where migration resistance is important. PMID:12632391

Lakshmi, S; Jayakrishnan, A

2003-04-15

444

Dyed polyvinyl chloride films for use as high-dose routine dosimeters in radiation processing  

NASA Astrophysics Data System (ADS)

Characteristics of the polyvinyl chloride (PVC) films containing 0.11 wt% of malachite green oxalate or 6GX-setoglausine and about 100 ?m in thickness were studied for use as routine dosimeters in radiation processing. These films show basically color bleaching under irradiation with 60Co ?-rays in a dose range of 5-50 kGy. The sensitivity of the dosimeters and the linearity of dose-response curves are improved by adding 2.5% of chloral hydrate [CCl 3CH(OH) 2] and 0.15% hydroquinone [HOC 6H 4OH]. These additions extend the minimum dose limit to 1 kGy covering dosimetry requirements of the quality assurance in radiation processing of food and healthcare products. The dose responses of both dyed PVC films at irradiation temperatures from 20°C to 35°C are constant relative to those at 25°C, and the temperature coefficients for irradiation temperatures from 35°C to 55°C were estimated to be (0.43±0.01)%/°C. The dosimeter characteristics are stable within 1% at 25°C before and 60 days after the end of irradiation.

Mai, Hoang Hoa; Duong, Nguyen Dinh; Kojima, Takuji

2004-04-01

445

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

446

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. PMID:24610881

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

2014-12-01

447

A visco-hyperelastic constitutive approach for modeling polyvinyl alcohol sponge.  

PubMed

This study proposes the quasi-linear viscoelastic (QLV) model to characterize the time dependent mechanical behavior of poly(vinyl alcohol) (PVA) sponges. The PVA sponges have implications in many viscoelastic soft tissues, including cartilage, liver, and kidney as an implant. However, a critical barrier to the use of the PVA sponge as tissue replacement material is a lack of sufficient study on its viscoelastic mechanical properties. In this study, the nonlinear mechanical behavior of a fabricated PVA sponge is investigated experimentally and computationally using relaxation and stress failure tests as well as finite element (FE) modeling. Hyperelastic strain energy density functions, such as Yeoh and Neo-Hookean, are used to capture the mechanical behavior of PVA sponge at ramp part, and viscoelastic model is used to describe the viscose behavior at hold part. Hyperelastic material constants are obtained and their general prediction ability is verified using FE simulations of PVA tensile experiments. The results of relaxation and stress failure tests revealed that Yeoh material model can define the mechanical behavior of PVA sponge properly compared with Neo-Hookean one. FE modeling results are also affirmed the appropriateness of Yeoh model to characterize the mechanical behavior of PVA sponge. Thus, the Yeoh model can be used in future biomechanical simulations of the spongy biomaterials. These results can be utilized to understand the viscoelastic behavior of PVA sponges and has implications for tissue engineering as scaffold. PMID:24405852

Karimi, Alireza; Navidbakhsh, Mahdi; Beigzadeh, Borhan

2014-02-01

448

Effect of salts on the electrospinning of poly(vinyl alcohol)  

NASA Astrophysics Data System (ADS)

Fibres with a diameter in the nanometer range were electrospun from aqueous poly(vinyl alcohol) (PVOH). In order to improve the mass deposition rate and decrease the final fibre diameter salts (NaCl, LiCl, LiBr and LiF) were added to the solution. The aim was to increase the charge density and hence increase the electrostatic forces on the fluid. It was found that with increasing salt concentration the charge density did increase. However the mass deposition rate was found to decrease and the final fibre diameter was found to increase. The decrease in mass deposition rate is explained by considering the concept of a virtual orifice. The increase in the final fibre diameter is explained by considering the charge distribution in the jet when it behaves like a conductor compared to when it behaves like an insulator. Both mechanisms result from the increase in conductivity of the PVOH solution without significantly modifying other solution properties when salt is added.

Stanger, Jonathan J.; Tucker, Nick; Staiger, Mark; Kirwan, Kerry; Coles, Stuart; Jacobs, Daniel; Larsen, Nigel

2009-07-01

449

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

450

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

451

Dielectric relaxation and alternating current conductivity of lanthanum, gadolinium, and erbium-polyvinyl alcohol doped films  

NASA Astrophysics Data System (ADS)

Fourier transform infrared (FTIR) spectrum dielectric constant, ?', loss tangent, tan(?), electric modulus, M*, and ac conductivity, ?ac, of pure polyvinyl alcohol (PVA) as well as La-, Gd-, and Er-PVA doped samples have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 300-450 K and 1 kHz-4 MHz, respectively. FTIR measurements reveal that La3+, Gd3+, and Er3+ ions form complex configuration within PVA structure. Two relaxation processes, namely, ? and ? were observed in pure PVA sample. The first process is due to the interfacial or Maxwell-Wagner-Sillers polarization. The second one is related to the micro-Brownian motion of the main chains. For doped PVA samples, ?-relaxation process splits into ?a and ?c. This splitting is due to the segmental motion in the amorphous (?a) and crystalline (?c) phases of PVA matrix. Electric modulus analysis was discussed to understand the mechanism of the electrical transport process. The behavior of ac conductivity for all PVA samples indicates that the conduction mechanism is correlated barrier hopping.

Hanafy, Taha A.

2012-08-01

452

Preparation of nanocrystalline cellulose via ultrasound and its reinforcement capability for poly(vinyl alcohol) composites.  

PubMed

Rod-shaped nanocrystalline cellulose (NCC) was prepared from microcrystalline cellulose (MCC) using the purely physical method of high-intensity ultrasonication. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction was used for the characterization of the morphology and crystal structure of the material. The thermal properties were investigated using thermogravimetric analysis. The reinforcement capabilities of the obtained NCC were investigated by adding it to poly(vinyl alcohol) (PVA) via the solution casting method. The results revealed that the prepared NCC had a rod-shaped structure, with diameters between 10 and 20 nm and lengths between 50 and 250 nm. X-ray diffraction results indicated that the NCC had the cellulose I crystal structure similar to that of MCC. The crystallinity of the NCC decreased with increasing ultrasonication time. The ultrasonic effect was non-selective, which means it can remove amorphous cellulose and crystalline cellulose. Because of the nanoscale size and large number of free-end chains, the NCC degraded at a slightly lower temperature, which resulted in increased char residue (9.6-16.1%), compared with that of the MCC (6.2%). The storage modulus of the nanocomposite films were significantly improved compared with that of pure PVA films. The modulus of PVA with 8 wt.% NCC was 2.40× larger than that of pure PVA. PMID:22153226

Li, Wei; Yue, Jinquan; Liu, Shouxin

2012-05-01

453

Poly(vinyl alcohol)/sodium alginate/layered silicate based nanofibrous mats for bacterial inhibition.  

PubMed

Poly(vinyl alcohol) (PVA)/sodium alginate (ALG)/organic rectorite (OREC) composite nanofibrous mats are fabricated by electrospinning aqueous solutions with different mixing ratios. Both good fiber shape and three-dimensional structure of nanofibrous mats can be observed by Field Emission Scanning Electron Microscopy. Energy-dispersive X-ray spectroscopy shows the existence of OREC in the as-spun composite mats. In addition, small-angle X-ray diffraction confirms that the interlayer of OREC is intercalated by ALG/PVA chains, and the distance between OREC interlayers is increased from 4.50 to 4.74 nm. Wide angle X-ray diffraction and Fourier transform infrared spectra further verify the intercalation is between polymers and layered silicate. Moreover, the thermal gravimetric analysis shows that the addition of OREC has only a small effect on the thermal stability of composites. Furthermore, the antibacterial experiments illustrate that OREC can enhance the bacterial inhibition ability of nanofibrous mats against Escherichia coli and Staphylococcus aureus. PMID:23399282

Li, Wei; Li, Xueyong; Chen, Yang; Li, Xiaoxia; Deng, Hongbing; Wang, Ting; Huang, Rong; Fan, Gang

2013-02-15

454

Surface properties of UV-irradiated poly(vinyl alcohol) films containing small amount of collagen  

NASA Astrophysics Data System (ADS)

The surface properties of poly(vinyl alcohol) (PVA) films in the presence of 1%, 3% and 5% of collagen before and after UV-irradiation have been studied by atomic force microscopy (AFM) and by contact angle measurements. PVA films have been obtained by solvent evaporation from water solution of PVA and PVA containing small amount of collagen. After drying, the samples were irradiated with UV light wavelength ? = 254 nm in air. Surface properties before and after UV-irradiation were observed using AFM. Contact angles of two liquids: diiodomethane (D) and glycerol (G) on polymeric films were measured at constant temperature using goniometer. The results have shown that the contact angle and the surface free energy for PVA films were altered by UV-irradiation. These alterations indicate photooxidation and an increase of polarity of the surface. The comparison of surface properties of PVA films and PVA containing collagen points out that collagen is more sensitive to photooxidation than PVA and PVA/collagen blends. PVA films containing collagen easier undergo photooxidation process with formation of new polar groups than pure PVA films.

Sionkowska, Alina; P?anecka, Anna; Koz?owska, Justyna; Skopi?ska-Wi?niewska, Joanna

2009-01-01

455

Melt-processed poly(vinyl alcohol) composites filled with microcrystalline cellulose from waste cotton fabrics.  

PubMed

Waste cotton fabrics (WCFs), which are generated in a large volume from the textile industry, have caused serious disposal problem. Recycling WCFs into value-added products is one of the vital measures for both environmental and economic benefits. In this study, microcrystalline cellulose (MCC) was prepared by acid hydrolysis of WCFs, and used as reinforcement for melt-processed poly(vinyl alcohol) (PVA) with water and formamide as plasticizer. The microstructure and mechanical properties of the melt-processed PVA/MCC composites were characterized by Fourier transform infrared spectra, Raman spectra, differential scanning calorimetry, thermal gravimetric analysis, X-ray diffraction, tensile tests and dynamic mechanical analysis. The results indicated that MCC could establish strong interfacial interaction with PVA through hydrogen bonding. As a result, the crystallization of PVA was confined and its melting temperature was decreased, which was beneficial for the melt-processing of PVA. Compared with the unfilled PVA, the PVA/MCC composites exhibited remarkable improvement in modulus and tensile strength. PMID:24299821

Sun, Xunwen; Lu, Canhui; Liu, Yong; Zhang, Wei; Zhang, Xinxing

2014-01-30

456

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

457

Mechanism of nonphotochemical hole burning: Cresyl Violet in polyvinyl alcohol films  

SciTech Connect

Polarized nonphotochemical hole-burned spectra of Cresyl Violet in polyvinyl alcohol films are presented for various burn temperatures (T{sub B}). For T{sub B}=15 K, but not for T{sub B}=2.2 K, a significant rotation of Cresyl Violet is indicated. The broad, tailing antihole is observed to depend on T{sub B}. The quantum efficiency distributions for the zero-phonon hole and pseudo-phonon sideband are quite similar, proving that the phonons created by excitation of the phonon sideband are not important for hole burning. The quantum efficiency is independent of T{sub B} over the range studied, 1.6--15 K. Over this range essentially 100% of the zero-phonon lines can be burned. The results show that the standard two-level-system (extrinsic) model for nonphotochemical hole burning is inadequate. The results are discussed in terms of an outside--in hierarchy of configurational relaxation events model (Chem. Phys. {bold 141}, 447 (1990)) as well as other models.

Shu, L.; Small, G.J. (Department of Chemistry and Ames Laboratory U.S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States))

1992-05-01

458

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

459

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

460

Char characterization-thermal decomposition chemistry of poly(vinyl alcohol)  

SciTech Connect

Currently, due to concerns over the environmental effects of halogenated compound, there is an international demand for the control of polymer flammability without the use of halogenated additives. An alternative to the use of halogenated fire retardants, which control flammability primarily in the gas phase, is to control polymer flammability by manipulating the condensed phase chemistry. Our approach is to increase the amount of char that forms during polymer combustion. Char formation reduces, through crosslinking reactions, the amount of small volatile polymer pyrolysis fragments, or fuel, available for burning in the gas phase; this, in turn reduces the amount of heat feedback to the polymer surface. The char also insulates the underlying virgin polymer. The polymer we chose to investigate was polyvinyl alcohol, PVA, because it is one of the few linear, non-halogenated, aliphatic, polymers with a measurable (approximately 4%) char yield. We report the CP/MAS {sup 13}C NMR characterization of the fundamental condensed phase processes and structures which lead to char formation during the pyrolysis of poly (vinyl-alcohol), PVA, and PVA with nonhalogenated additives.

Gilman, J.W.; VanderHart, D.L.; Kashiwagi, Takashi [NIST, Gaithersburg, MD (United States)

1995-12-01

461

Layered double hydroxide-alginate/polyvinyl alcohol beads: fabrication and phosphate removal from aqueous solution.  

PubMed

In the water treatment field, powder form of layered double hydroxides (LDHs) has wide applications in adsorptions. However, its applications are limited because of low hydraulic conductivity. Here, LDH-alginate/polyvinyl alcohol (PVA) beads were fabricated by entrapment of the Mg-Al LDH powder into alginate/PVA beads. The obtained Mg-Al LDH-alginate/PVA beads were characterized by X-ray diffraction scanning electron microscopy. Their performance for phosphate removal by batch and column adsorption mode was evaluated. The Mg-Al LDH-alginate/PVA beads were found to be efficient adsorbents for phosphate removal. Batch adsorption experiment showed that the phosphate sorption process on the Mg-Al LDH-alginate/PVA beads followed pseudo-second-order reaction order kinetic model and the adsorption isotherm date could be simulated using both Langmiur and Freundlich models. In the column study, the flow rate and inlet phosphate concentration were maintained at 29.62 m³/m² h and 10 mgP/L, respectively. Using 20 cm column depth, the breakthrough and exhaust time were found to be 5 and 31 h, respectively. The percentage of phosphate removal by column was 80.09%. The values of adsorption rate coefficient (K) and the adsorption capacity coefficient (N) were 0.0125 L/mg h and 258.32 mg/L, respectively. PMID:25176487

Kim Phuong, Nguyen Thi

2014-01-01

462

Dispersive kinetics of nonphotochemical hole burning and spontaneous hole filling: Cresyl Violet in polyvinyl films  

SciTech Connect

The dispersive kinetics of nonphotochemical burning and spontaneous filling of the zero-phonon hole of Cresyl Violet in polyvinyl alcohol at 1.6 K are analyzed in terms of the standard external two-level system (TLS{sub {ital ezt}}) model for probe--glass systems and a distribution function for the tunnel frequency derived from a normal distribution function for the tunnel parameter {lambda}. Average values for the relaxation rates for burning and filling are determined. It is shown that the dominant mechanism for filling is not global spectral diffusion but rather antihole reversion. A high degree of positive correlation between the rates of burning and filling associated with the TLS{sub {ital ext}} is found. A new methodology that permits a more physically reasonable interpretation of spontaneous hole-filling kinetics is described. It is based on the hypothesis that only a fraction of burned sites, on reversion to the ground state, yield sites with resonance frequencies that lie within the hole profile.

Shu, L.; Small, G.J. (Department of Chemistry and Ames Laboratory U.S. Department of Energy, Iowa State University, Ames, Iowa 50011 (United States))

1992-05-01

463

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

464

Reject water treatment by improvement of whole cell anammox entrapment using polyvinyl alcohol/alginate gel.  

PubMed

Reject water treatment performance was investigated by whole cell anammox sludge entrapped polyvinyl alcohol/sodium alginate gel in the stirred tank reactor (STR). The whole experiment was conducted through Phase 1 and Phase 2 in which synthetic wastewater and modified reject water were used as feeding medium, respectively. The anammox reactor demonstrated quick start-up after 22 days as well as stable and relatively high nitrogen removal rate of more than 8.0 kg-N m(-3) day(-1) during the two both phases even under moderately low temperature of 25 ± 0.5°C during the last 2 months of Phase 2. The matured brownish red PVA beads had good characteristics with buoyant density of 1.10 g cm(-3), settling velocity of 141 m h(-1) and diameter of 4 mm. The bacterial community was identified by 16S rDNA analysis revealing the concurrent existence of KSU-1 and new kind anammox bacterium Kumadai-I after changing influent from synthetic wastewater to reject water. It was speculated that Kumadai-I might play a role as "promotion" factor together with KSU-1 on high nitrogen removal rate. These results demonstrate the potential application of whole cell anammox entrapment by PVA/alginate gel for achieving stable and high-rate nitrogen removal from high ammonium with low C/N ratio contained wastewaters, such as reject water, digester liquor or landfill leachate. PMID:21455769

Quan, Lai Minh; Khanh, Do Phuong; Hira, Daisuke; Fujii, Takao; Furukawa, Kenji

2011-11-01

465

Study of ionic liquid immobilization on polyvinyl ferrocene substrates for gas sensor arrays.  

PubMed

In this report, the effects of conductive polymer oxidation states and structures on the design and development of ionic liquid (IL)/conductive polymer (CP) composite films for gas sensing are systematically characterized. Four different polyvinyl ferrocene (PVF) films synthesized by varying the conditioning potential (0.7 vs 0.0 V) and the electrolyte are tested for their gas-sensing properties (e.g., sensitivity, selectivity, response time, linearity, and dynamic range against various gas analytes such as dichloromethane, ethanol, natural gas, methane, formaldehyde (37%), and benzene) utilizing the quartz crystal microbalance (QCM) and ATR-FT-IR. The best available film is further studied as a substrate for the immobilization of various ILs that enhanced both the sensitivity and selectivity. Finally, two arrays, each comprising four sensors with the following scheme are developed and characterized for their ability to classify the four target analytes by using linear discriminant analysis: (1) the highest sensitivity PVF film immobilized with four different ILs and (2) the highest sensitivity IL immobilized in four different PVF films. Array 2 is proven to be much better than array 1 in discriminating the analytes, which is very significant in establishing the fact that a diverse set of PVF redox states allow the rational development of a PVF/IL composite-based sensor array in order to analyze complex mixtures utilizing structural differences and the extent of intermolecular interactions. PMID:21410206

Hou, Kuang-Yu; Rehman, Abdul; Zeng, Xiangqun

2011-04-19

466

Preparation of cellulose/polyvinyl alcohol biocomposite films using 1-n-butyl-3-methylimidazolium chloride.  

PubMed

This study has been focused on developing cellulose/polyvinyl alcohol (PVA), a biocomposite film, pretreated with 1-n-butyl-3-methylimidazolium chloride ([bmim]Cl). The dissolved polymers were blended and their biocomposite films including cellulose and cellulose/PVA were prepared. The effect of PVA composition with cellulose was evaluated by comparing the physical, mechanical, chemical and thermal characteristics of produced films with neat cellulosic film. The results showed that the ionic liquid had a great capability in dissolving the polymers. Furthermore, in composition of the raw cellulose some chemical bonds were incorporated between the two components. Water uptake, thickness swelling and water vapor permeability of blend films were increased comparing to cellulosic film. Mechanical strength and Young's modulus of the films made of cellulose/PVA were decreased while the strain at break was increased. The optical transparency and thermal properties of the blend films were almost the same as neat cellulosic film. This work demonstrated a promising route for the preparation of biodegradable green composites. In addition, this biocomposite film is composed of sustainable biodegradable resources, which is suitable for release to the environment. The biocomposite films showed good optical transparency, thermal stabilities properties. PMID:24076203

Abdulkhani, Ali; Hojati Marvast, Ebrahim; Ashori, Alireza; Hamzeh, Yahya; Karimi, Ali Naghi

2013-11-01

467

Swelling and flow properties of tubular poly(vinyl alcohol) gels.  

PubMed

Swelling and flow properties of tubular poly(vinyl alcohol) (PVA) hydrogels prepared with the cooling method were investigated using an inflation testing method. When the tubular hydrogel in liquid paraffin was inflated by using liquid paraffin as a pressure transmitting medium, namely in the case that the liquids inside and outside the gel are both liquid paraffin (P/P combination), the gel showed a slight volume change determined by Poisson's ratio of the gel. When the gel in water was inflated by liquid paraffin (P/W combination), the gel swelled to large extent compared with the case of P/P. The hydrogel in W/W combination, namely in the situation that the gel was immersed in water and also inflated by water, showed a very large volume change if the comparison was done at the same pressure. The origin of the volume change in P/P, P/W and W/W combinations is discussed. The volume change in P/P was governed by the Poisson ratio as a material constant (mu 0) of the PVA gels, and the gels swelled by the change in the application of pressure (or deformation) in P/W. The volume change in W/W was closely related to the flow of solvent in the gel. PMID:10818638

Takigawa, T; Uchida, K; Takahashi, K; Masuda, T

1999-01-01

468

In-Line Ultrasonic Monitoring for Sediments Stuck on Inner Wall of a Polyvinyl Chloride Pipe  

PubMed Central

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

2014-01-01

469

21 CFR 584.200 - Ethyl alcohol containing ethyl acetate.  

Code of Federal Regulations, 2013 CFR

...added the equivalent of 4.25 gallons of 100 percent ethyl acetate. It is used in accordance with good feeding practices in ruminant feed supplements as a source of added energy. [46 FR 52333, Oct. 27, 1981, as amended at 72 FR 41620, July 31,...

2013-04-01

470

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

471

Redox responses in yeast to acetate as the carbon source.  

PubMed

Following a shift to medium with acetate as the carbon source, a parental yeast strain exhibited a transient moderate 20% reduction in total cellular [NAD(+)+NADH] but showed a approximately 10-fold increase in the ratio of [NAD(+)]:[NADH] after 36h. A mutant strain (idhDelta) lacking the tricarboxylic acid cycle enzyme isocitrate dehydrogenase had 50% higher cellular levels of [NAD(+)+NADH] relative to the parental strain but exhibited similar changes in cofactor concentrations following a shift to acetate medium, despite an inability to grow on that carbon source; essentially all of the cofactor was in the oxidized form within 36h. The salvage pathway for NAD(H) biosynthesis was found to be particularly important for viability during early transition of the parental strain to stationary phase in acetate medium. However, oxygen consumption was not affected, suggesting that the NAD(H) produced during this time may support other cellular functions. The idhDelta mutant exhibited increased flux through the salvage pathway in acetate medium but was dependent on the de novo pathway for viability. Long-term chronological lifespans of the parental and idhDelta strains were similar, but viability of the mutant strain was dependent on both pathways for NAD(H) biosynthesis. PMID:19138656

Minard, Karyl I; McAlister-Henn, L

2009-03-01

472

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...

473

Effects of nitrophenols on acetate utilizing methanogenic systems  

Microsoft Academic Search

Nitrophenols are widely used for manufacturing explosives, pharmaceuticals, pesticides, pigments, dyes, etc. A literature research shows that there is a lack of quantitative information on the effects of nitrophenols on anaerobic systems. The objective of this research was to study the toxic effects of nitrophenols on acetate enrichment, methanogenic systems. Anaerobic toxicity assays were performed with batch serum bottles. Results

Mohammad R. Haghighi Podeh; Sanjoy K. Bhattacharya; Mingbo Qu

1995-01-01

474

Computerized image analysis for acetic acid induced intraepithelial lesions  

Microsoft Academic Search

Cervical Intraepithelial Neoplasia (CIN) exhibits certain morphologic features that can be identified during a visual inspection exam. Immature and dysphasic cervical squamous epithelium turns white after application of acetic acid during the exam. The whitening process occurs visually over several minutes and subjectively discriminates between dysphasic and normal tissue. Digital imaging technologies allow us to assist the physician analyzing the

Wenjing Li; Daron G. Ferris; Rich W. Lieberman

2008-01-01

475

Condensation of acetol and acetic acid vapor with sprayed liquid  

Technology Transfer Automated Retrieval System (TEKTRAN)

A cellulose-derived fraction of biomass pyrolysis vapor was simulated by evaporating acetol and acetic acid (AA) from flasks on a hot plate. The liquid in the flasks was infused with heated nitrogen. The vapor/nitrogen stream was superheated in a tube oven and condensed by contact with a cloud of ...

476

Intrinsic hydration of monopositive uranyl hydroxide, nitrate, and acetate cations.  

PubMed

The intrinsic hydration of three monopositive uranyl-anion complexes (UO(2)A)(+) (where A = acetate, nitrate, or hydroxide) was investigated using ion-trap mass spectrometry (IT-MS). The relative rates for the formation of the monohydrates [(UO(2)A)(H(2)O)](+), with respect to the anion, followed the trend: Acetate > or = nitrate > hydroxide. This finding was rationalized in terms of the donation of electron density by the strongly basic OH(-) to the uranyl metal center, thereby reducing the Lewis acidity of U and its propensity to react with incoming nucleophiles, viz., H(2)O. An alternative explanation is that the more complex acetate and nitrate anions provide increased degrees of freedom that could accommodate excess energy from the hydration reaction. The monohydrates also reacted with water, forming dihydrates and then trihydrates. The rates for formation of the nitrate and acetate dihydrates [(UO(2)A)(H(2)O)(2)](+) were very similar to the rates for formation of the monohydrates; the presence of the first H(2)O ligand had no influence on the addition of the second. In contrast, formation of the [(UO(2)OH)(H(2)O)(2)](+) was nearly three times faster than the formation of the monohydrate. PMID:15144967

Chien, Winnie; Anbalagan, Victor; Zandler, Melvin; Van Stipdonk, Michael; Hanna, Dorothy; Gresham, Garold; Groenewold, Gary

2004-06-01

477

[Metabolism of C(14)-acetate by some trematodes  

PubMed

The adult trematodes, Fasciola hepatica, Eurytrema pancreaticum and Paramphistomum cervi, employed in this experiment were obtained from the cattle slaughtered at the local abbatoir. The worms selected and washed several times in normal sterilized saline solution. Each about ten of intact F. hepatica, fourty of E. pancreaticum, and twenty of P. cervi were incubated in 50 cc volume of special incubation flasks with incubation medium consisting of 10 cc. of Krebs-Ringer phosphate buffer(pH 7.4) The incubation medium was added C(14)-1-acetate and non-radioactive carrier Na-acetate so as to contain acetate concentration of 50 mg per cent. The worms were allowed to incubate for 5 hours in the Dubnoff metabolic shaking incubator at 38 degrees C. After incubation period, respiratory CO2 samples from central well of incubation flask were analysed for total CO2 production rate and their specific activity of respiratory CO2. The lactate and pyruvate appearance rates were determined by analyzing the lactate and pyruvate concentration in a medium after incubation. The glycogen samples isolated from worms were analyzed for the tissue concentration and their radioactivities in order to determine the turnover rate of glycogen pool. Radioactivities of these series of experiments were counted by an endwindow Geiger-Muller counter as an infinitely thin samples. The quantitative analysis of C(14)-acetate utilized by F. hepatica, E. pancreaticum and P. cervi were compared and discussed in this report. According to these data of the experiment, it is suggested that the fatty acid such as acetate may play a part of their oxidative process into the respiratory CO2 and the synthetic process into glycogen in the above species of trematodes. PMID:12913583

Seo, Byong Seol; Rim, Han Jong; Min, Yong Ok; Rhee, Sang Don; Lee, Tong Hoon; Yun, Myong Soon

1965-12-01

478

The Key to Acetate: Metabolic Fluxes of Acetic Acid Bacteria under Cocoa Pulp Fermentation-Simulating Conditions  

PubMed Central

Acetic acid bacteria (AAB) play an important role during cocoa fermentation, as their main product, acetate, is a major driver for the development of the desired cocoa flavors. Here, we investigated the specialized metabolism of these bacteria under cocoa pulp fermentation-simulating conditions. A carefully designed combination of parallel 13C isotope labeling experiments allowed the elucidation of intracellular fluxes in the complex environment of cocoa pulp, when lactate and ethanol were included as primary substrates among undefined ingredients. We demonstrate that AAB exhibit a functionally separated metabolism during coconsumption of two-carbon and three-carbon substrates. Acetate is almost exclusively derived from ethanol, while lactate serves for the formation of acetoin and biomass building blocks. Although this is suboptimal for cellular energetics, this allows maximized growth and conversion rates. The functional separation results from a lack of phosphoenolpyruvate carboxykinase and malic enzymes, typically present in bacteria to interconnect metabolism. In fact, gluconeogenesis is driven by pyruvate phosphate dikinase. Consequently, a balanced ratio of lactate and ethanol is important for the optimum performance of AAB. As lactate and ethanol are individually supplied by lactic acid bacteria and yeasts during the initial phase of cocoa fermentation, respectively, this underlines the importance of a well-balanced microbial consortium for a successful fermentation process. Indeed, AAB performed the best and produced the largest amounts of acetate in mixed culture experiments when lactic acid bacteria and yeasts were both present. PMID:24837393

Adler, Philipp; Frey, Lasse Jannis; Berger, Antje; Bolten, Christoph Josef; Hansen, Carl Erik

2014-01-01

479

Water requirements of the rayon- and acetate-fiber industry  

USGS Publications Warehouse

Water is required for several purposes in the manufacture of rayon and acetate fiber. These water requirements, as indicated by a survey of the water used by the plants operating in 1953, are both quantitative and qualitative. About 300 mgd (million gallons per day) of water was used in 1953 in the preparation of purified wood cellulose and cotton linters, the basic material from which the rayon and acetate fiber is made. An additional 620 mgd was used in the process of converting the cellulose to rayon and acetate fiber. The total, 920 mgd, is about 1 percent of the total estimated withdrawals of industrial water in the United States in 1953. The rayon- and acetate-fiber plants are scattered through eastern United States and generally are located in small towns or rural areas where there are abundant supplies of clean, soft water. Water use at a typical rayon-fiber plant was about 9 mgd, and at a typical acetate-fiber plant about 38 mgd. About 110 gallons of water was used to produce a pound of rayon fiber, 32 gallons per pound was process water and the remainder was used largely for cooling in connection with power production and air conditioning. For the manufacture of a pound of acetate fiber about 170 gallons of water was used. However, the field survey on which this report is based indicated a wide range in the amount of water used per pound of product. For example, in the manufacture of viscose rayon, the maximum unit water use was 8 times the minimum unit water use. Water use in summer was about 22 percent greater than average annual use. About 8 mgd Of water was consumed by evaporation in the manufacture of rayon and acetate fiber. More than 90 percent of the water used by the rayon and acetate industry was with- drawn from surface-water sources, about 8 percent from ground water, and less than 2 percent from municipal water supplies. All available analyses of the untreated waters used by the rayon and acetate industry were collected and studied. The untreated waters were generally cool, low in content of calcium and magnesium, and very low in iron and manganese. At many plants, water was obtained from more than one source, and thus had different quality characteristics. Dissolved solids in all the untreated waters analyzed ranged between 14 and 747 ppm (parts per million) but in those waters used in processing the dissolved solids content was less than 200 ppm. The cooling water used by the industry is also generally of very high quality, principally because the requirements for a high-quality process water necessitate location of the plants in areas where such water is available.

Mussey, Orville Durey

1957-01-01

480

Chemical modification of polyvinyl chloride and silicone elastomer in inhibiting adhesion of Aeromonas hydrophila.  

PubMed

Disease-causing bacteria of the genus Aeromonas are able to adhere to pipe materials, colonizing the surfaces and forming biofilms in water distribution systems. The aim of our research was to study how the modification of materials used commonly in the water industry can reduce bacterial cell attachment. Polyvinyl chloride and silicone elastomer surfaces were activated and modified with reactive organo-silanes by coupling or co-crosslinking silanes with the native material. Both the native and modified surfaces were tested using the bacterial strain Aeromonas hydrophila, which was isolated from the Polish water distribution system. The surface tension of both the native and modified surfaces was measured. To determine cell viability and bacterial adhesion two methods were used, namely plate count and luminometry. Results were expressed in colony-forming units (c.f.u.) and in relative light units (RLU) per cm(2). Almost all the chemically modified surfaces exhibited higher anti-adhesive and anti-microbial properties in comparison to the native surfaces. Among the modifying agents examined, poly[dimethylsiloxane-co-(N,N-dimethyl-N-n-octylammoniopropyl chloride) methylsiloxane)] terminated with hydroxydimethylsilyl groups (20 %) in silicone elastomer gave the most desirable results. The surface tension of this modifier, was comparable to the non-polar native surface. However, almost half of this value was due to the result of polar forces. In this case, in an adhesion analysis, only 1 RLU cm(-2) and less than 1 c.f.u. cm(-2) were noted. For the native gumosil, the results were 9,375 RLU cm(-2) and 2.5 × 10(8) c.f.u. cm(-2), respectively. The antibacterial activity of active organo-silanes was associated only with the carrier surface because no antibacterial compounds were detected in liquid culture media, in concentrations that were able to inhibit cell growth. PMID:23397109

Kregiel, Dorota; Berlowska, Joanna; Mizerska, Urszula; Fortuniak, Witold; Chojnowski, Julian; Ambroziak, Wojciech

2013-07-01

481

Polyvinyl alcohol: an efficient fuel for synthesis of superparamagnetic LSMO nanoparticles for biomedical application.  

PubMed

La(0.7)Sr(0.3)MnO(3) (LSMO) nanoparticles have been prepared using glycine and polyvinyl alcohol (PVA) as fuels. Their crystal structure, particle morphology and compositions are characterized using X-ray diffraction, transmission electron microscopy, field-emission electron microscopy and energy dispersive analysis of X-ray. They show a pseudo-cubic perovskite structure. The spherical particle sizes of 30 and 20 nm have been obtained from samples prepared by glycine and PVA respectively. The field cooled (FC) and zero field cooled (ZFC) magnetizations have been recorded from 5 to 375 K at 500 Oe and superparamagnetic blocking temperatures (T(B)) of 75 and 30 K are obtained from samples prepared by glycine and PVA respectively. Particle size distribution is observed from dynamic light scattering measurements. Dispersion stability of the particles in water is studied by measuring the Zeta potential with varying the pH of the medium from 1 to 12. Under induction heating experiments, a hyperthermia temperature (42-43 °C) is achieved by both the samples (3-6 mg mL(-1)) at magnetic fields of 167-335 Oe and at a frequency of 267 kHz. The bio-compatibility of the LSMO nanoparticles is studied on the L929 and HeLa cell lines by MTT assay for up to 48 h. The present work reveals the importance of synthesis technique and fuel choice on structural, morphological, magnetic, hyperthermia and biocompatible properties of LSMO and predicts the suitability for biomedical applications. PMID:22277953

Thorat, N D; Shinde, K P; Pawar, S H; Barick, K C; Betty, C A; Ningthoujam, R S

2012-03-14

482

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

483

Analysis of isothiazolinone preservatives in polyvinyl alcohol cooling towels used in Japan.  

PubMed

Recently, cases of contact dermatitis that were related to the use of polyvinyl alcohol (PVA) cooling towels containing isothiazolinone preservatives were reported in Japan. The aim of this investigation was to analyze the concentrations of five different isothiazolinone compounds present in PVA towels and to assess the effectiveness of washing in removing the preservatives from new towels prior to being used for the first time. Twenty-seven PVA towels were used in this study. Two groups (i.e., lab