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Sample records for 125i-labelled polyvinyl pyrrolidone

  1. Macrophage clearance of 125I-labelled polyvinyl pyrrolidone in the horse: effect of ovarian steroids and persistent endometritis.

    PubMed

    Watson, E D; Stokes, C R

    1988-11-01

    The rate of clearance of 125I-labelled polyvinyl pyrrolidone (PVP) from blood was measured in mares as an indicator of macrophage function. In three out of four cycling mares, PVP clearance was slower during oestrus than dioestrus. Similarly, administration of oestrogen to four ovariectomised mares tended to depress PVP clearance compared with clearance from the same mares before they received oestrogen. However, the effect of oestrogen was not statistically significant. Mares susceptible to persistent endometritis had rates of PVP clearance which were similar to those of genitally normal mares.

  2. Scintillation Proximity Radioimmunoassay Utilizing 125I-Labeled Ligands

    NASA Astrophysics Data System (ADS)

    Udenfriend, Sidney; Diekmann Gerber, Louise; Brink, Larry; Spector, Sydney

    1985-12-01

    A unique type of radioimmunoassay is described that does not require centrifugation or separation. Microbeads containing a fluorophor are covalently linked to antibody. When an 125I-labeled antigen is added it binds to the beads and, by its proximity, the emitted short-range electrons of the 125I excite the fluorophor in the beads. The light emitted can be measured in a standard scintillation counter. Addition of unlabeled antigen from tissue extracts displaces the labeled ligand and diminishes the fluorescent signal. Application of scintillation proximity immunoassay to tissue enkephalins, serum thyroxin, and urinary morphine is described. Applications of the principle to study the kinetics of interaction between receptors and ligands are discussed.

  3. Scintillation proximity radioimmunoassay utilizing 125I-labeled ligands

    SciTech Connect

    Udenfriend, S.; Gerber, L.D.; Brink, L.; Spector, S.

    1985-12-01

    A unique type of radioimmunoassay is described that does not require centrifugation or separation. Microbeads containing a fluorophor are covalently linked to antibody. When an /sup 125/I-labeled antigen is added it binds to the beads and, by its proximity, the emitted short-range electrons of the /sup 125/I excite the fluorophor in the beads. The light emitted can be measured in a standard scintillation counter. Addition of unlabeled antigen from tissue extracts displaces the labeled ligand and diminishes the fluorescent signal. Application of scintillation proximity immunoassay to tissue enkephalins, serum thyroxin, and urinary morphine is described. Applications of the principle to study the kinetics of interaction between receptors and ligands are discussed.

  4. Mineralization of radiation-crosslinked polyvinyl alcohol/polyvinyl pyrrolidone hydrogels.

    PubMed

    Hill, David J T; Whittaker, Andrew K

    2007-11-01

    A study of the calcification of the polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) hydrogels during their exposure to a calcium chloride solution or a simulated body fluid has been carried out. On the basis of the experiments, using a two-compartment permeation cell, the diffusion of calcium ions and their subsequent deposition in the hydrogels were elucidated. Steady-batch experiments were also performed to further elaborate the deposition pattern and the types of calcium deposits. It was demonstrated that Fick's second law of diffusion can describe the diffusion of calcium ions through PVA/PVP hydrogels at 310 K. The diffusion coefficient was determined to be (4.4+/-0.1)x10(-10) m2/s and the partition coefficient for the hydrogels was 0.06. Formation of calcium deposits was noticed taking place both on the surface and inside the hydrogels. The deposits formed on the surface have flake morphology, while the deposits inside the hydrogels are more like globular aggregates. Both types of deposits have been characterized as being comprised calcium and hydroxyl ion deficient apatites with chloride ions the most likely substituting species at the hydroxyl sites.

  5. Increased /sup 125/I-labelled concanavalin A binding to erythrocytes in diabetes mellitus

    SciTech Connect

    Okada, Y.; Arima, T.; Okazaki, S.; Nakata, K.; Nagashima, H.; Yamabuki, T.

    1982-03-01

    Percentage binding of /sup 125/I-labelled concanavalin A to erythrocytes in diabetic patients was significantly higher than that in normal subjects (12.2 +- 2.8 versus 8.1 +- 1.8%, mean +- SD, p < 0.001). Insulin-dependent diabetic patients showed significantly higher concanavalin A binding than non-insulin-dependent diabetic subjects (15.0 +- 1.4 versus 11.4 +- 2.5%, p < 0.01). There was a highly significant correlation between percentage binding of /sup 125/I-labelled concanavalin A and glycosylated haemoglobin.

  6. Use of immunoaffinity chromatography for purification of /sup 125/I-labeled human prolactin

    SciTech Connect

    Stuart, M.C.; Boscato, L.M.; Underwood, P.A.

    1983-02-01

    Researchers assessed a simple method for purifying /sup 125/I-labeled human prolactin, taking advantage of the abundant supplies of monoclonal antibodies available. /sup 125/I-labeled human prolactin purified by immunoaffinity chromatography is compared with that purified by gel filtration on Sephadex G-100. Researchers used monoclonal antibodies to prolactin to prepare the affinity chromatography columns. Prolactin was radiolabeled by the Chloramine T method, purified by each of the above procedures, and the binding and displacement characteristics were studied in radioimmunoassays in which either monoclonal antibodies or a rabbit anti-prolactin serum was the first antibody. A nonimmune fraction of /sup 125/I-labeled prolactin that co-eluted with the immunoreactive hormone from Sephadex G-100 was removed by affinity chromatography, which increased the antibody binding of /sup 125/I-labeled prolactin in the radioimmunoassay in the absence of unlabeled antigen (B/T0, in percent) twofold or more, increased the assay sensitivity, and increased the slope of antigen displacement measured by the 50% intercept. Several advantages make this the purification method of choice.

  7. Preparation and characterization of electrospun core sheath nanofibers from multi-walled carbon nanotubes and poly(vinyl pyrrolidone).

    PubMed

    Miao, Jianjun; Miyauchi, Minoru; Dordick, Jonathan S; Linhardt, Robert J

    2012-03-01

    Electrospinning is a versatile technique to prepare polymer fibers in nano to micrometer size ranges using very high electrostatic fields. Electrospun nanofibers with tunable porosity and high specific surface area have various applications, including chromatographic supports for protein separation, biomedical devices, tissue engineering and drug delivery matrices, and as key components in solar cells and supercapacitors. Unspinnable materials such as nanoparticles, nanorods, nanotubes or rigid conducting polymers can also be electrospun into fibers through co-axial electrospinning. In this study, we have prepared core-sheath nanofibers utilizing co-axial electrospinning. The core portion of these electrospun fibers consists of multi-walled carbon nanotubes and the sheath portion is poly(vinyl pyrrolidone) (PVP). Various morphologies were obtained by changing both core and sheath solution concentrations. The core-sheath nanofibers were characterized by scanning electron microscopy and transmission electron microscopy, to confirm core-sheath morphology, thermogravimetric analysis, and mechanical strength testing. The electrical conductivity of the surfaces of poly(vinyl pyrrolidone) fibers and poly(vinyl pyrrolidone)-multi-walled nanotube fibers were both 10(-15) S/m. The highest bulk conductivity observed for the poly(vinyl pyrrolidone)-multi-walled nanotube fibers was 1.2 x 10(-3) S/m.

  8. Derivatives of cyclosporin compatible with antibody-based assays. I. The generation of (/sup 125/I)-labeled cyclosporin

    SciTech Connect

    Mahoney, W.C.; Orf, J.W.

    1985-03-01

    The immunosuppressive drug cyclosporin A, has been successfully iodinated to a specific activity of 300 Ci per gram. /sup 125/I-labeled cyclosporin and (/sup 3/H)cyclosporin are nearly equivalent as tracers in a radioimmunoassay in producing standard lines (suppression by unlabeled cyclosporin) and in assigning values to clinical samples. In addition, the (/sup 125/I)-labeled cyclosporin has greater than twice the sensitivity, and it is stable to long-term storage. Use of a (/sup 125/I)-labeled cyclosporin tracer is more convenient, more reproducible, more precise, and easier than the tritiated-cyclosporin alternative in radioimmunoassay of this compound.

  9. Highly water-dispersible silver sulfadiazine decorated with polyvinyl pyrrolidone and its antibacterial activities.

    PubMed

    Li, Ping; Wu, Longlong; Li, Binjie; Zhao, Yanbao; Qu, Peng

    2016-03-01

    Highly water-dispersible silver sulfadiazine (SSD) was prepared by liquid phase method with polyvinyl pyrrolidone (PVP) as a surface modification agent. The structure and morphology of the PVP-modified silver sulfadiazine (P-SSD) were investigated by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier-transform infrared (FT-IR) spectrometry. The produced particles are ginkgo leaf-like architecture with the sizes of micron-nanometer. Due to hydrophilic PVP decorated on the surface, the P-SSD has excellent dispersion in water over a period of 24h, which is obviously stable by comparison to that of the commercial silver sulfadiazine (C-SSD). In addition, the P-SSD exhibits good antibacterial activities against Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus).

  10. Broadband Dielectric Study on Dynamics of Poly(vinyl pyrrolidone)-Poly(ethylene glycol) Blend

    NASA Astrophysics Data System (ADS)

    Tsubotani, S.; Sudo, S.; Nakamura, H.; Shinyashiki, N.; Yagihara, S.; Sengwa, R. J.

    2004-04-01

    Dielectric measurements for blends of poly(vinyl pyrrolidone) (PVP) (Mw=40,000) and poly(ethylene glycol) (PEG) (Mw=400) with various compositions were carried out in the frequency range of 1μHz to 10GHz and temperatures range between 298 and 173K. Three relaxation processes were observed above 298K. The high frequency process (h1 process) is caused by the chain motion of PEG, the middle frequency process (m process) is caused by the segmental motion of PVP chains, and the low frequency process is caused by ionic impurities in the mixture. The relaxation time of h1 process increased with decreasing temperature and separated into two processes at 253K. Moreover h1 process was separated again at 223K. The relaxation time of h1 process was 100s at 208K. The glass transition is attributed to the motion of unfrozen PEG molecules.

  11. Endocytosis and subsequent processing of 125I-labelled immunoglobulin G by guinea pig yolk sac in vitro.

    PubMed Central

    Douglas, G C; King, B F

    1985-01-01

    We have developed conditions for studying the binding, uptake, degradation and transport of 125I-labelled IgG by yolk sac in vitro. Specific binding to tissue at 4 degrees C and to paraformaldehyde-treated tissue at 37 degrees C was time- and temperature-dependent and showed saturation kinetics (Kd,4 degrees C = 2.9 X 10(-6) M, Kd,37 degrees C = 5.3 X 10(-6) M). Uptake was studied at 37 degrees C using untreated tissue (K uptake = 13.3 X 10(-6) M) and was inhibited by preincubation with metabolic poisons but not with cycloheximide. Tissue that had been incubated with 125I-labelled IgG at 37 degrees C released radiolabelled degradation products and intact 125I-labelled IgG into the medium. Experiments with paraformaldehyde-treated and untreated tissue showed that release of intact 125I-labelled IgG was mostly the result of ligand dissociation from surface binding sites. However, more 125I-labelled IgG was released from untreated tissue than could be accounted for solely by loss of surface-bound ligand and the difference was presumed to reflect uptake, transport and exocytosis of 125I-labelled IgG. Degradation of 125I-labelled IgG was inhibited by leupeptin and lysosomotropic amines. These drugs had no detectable effect on 125I-labelled IgG release. The results suggest that degradation and transport of IgG are not intimately related and are consistent with a previously proposed model for IgG transport via coated vesicles which do not fuse with lysosomes and for non-selective uptake into another class of vesicle which does fuse with lysosomes. PMID:4004783

  12. Nanocomposite scaffold with enhanced stability by hydrogen bonds between collagen, polyvinyl pyrrolidone and titanium dioxide.

    PubMed

    Li, Na; Fan, Xialian; Tang, Keyong; Zheng, Xuejing; Liu, Jie; Wang, Baoshi

    2016-04-01

    In this study, three-dimensional (3D) nanocomposite scaffolds, as potential substrates for skin tissue engineering, were fabricated by freeze drying the mixture of type I collagen extracted from porcine skin and polyvinyl pyrrolidone (PVP)-coated titanium dioxide (TiO2) nanoparticles. This procedure was performed without any cross-linker or toxic reagents to generate porosity in the scaffold. Both morphology and thermal stability of the nanocomposite scaffold were examined. The swelling behavior, mechanical properties and hydrolytic degradation of the composite scaffolds were carefully investigated. Our results revealed that collagen, PVP and TiO2 are bonded together by four main hydrogen bonds, which is an essential action for the formation of nanocomposite scaffold. Using Coasts-Redfern model, we were able to calculate the thermal degradation apparent activation energy and demonstrated that the thermal stability of nanocomposites is dependent on amount of PVP incorporated. Furthermore, SEM images showed that the collagen fibers are wrapped and stabilized on scaffolds by PVP molecules, which improve the ultimate tensile strength (UTS). The UTS of PVP-contained scaffold is four times higher than that of scaffold without PVP, whereas ultimate percentage of elongation (UPE) is decreased, and PVP can enhance the degradation resistance.

  13. Intense quenching of fluorescence intensity of poly(vinyl pyrrolidone) molecules in presence of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Behera, M.; Ram, S.

    2013-12-01

    We study the quenching of fluorescence intensity of 40 g/L poly(vinyl pyrrolidone) PVP molecules by varying the content of gold nanoparticles (GNPs) from 1 to 5 μM in 1-butanol. A profound exponential decay of the emission band intensity in the π ← nπ* band of the PVP molecules at ~392 nm upon gradual addition of the GNPs demonstrates an existence of an excited state interaction of NPs with the PVP molecules in a gold colloid in 1-butanol. Such quenching is caused by the non-bonding electron transfer from the O-atom of carbonyl group of the PVP molecules to the surface of the GNP. X-ray photoemission spectroscopy (XPS) study corroborates the spectroscopic results. A linear Stern-Volmer plot with a quenching constant of 2.23 × 106 M-1 reveals dynamic quenching in a non-aqueous NF. A mechanism of fluorescence quenching was proposed in support of XPS and images taken from hybrid nanostructure using transmission electron microscope. Study on quenching of fluorescence intensity of PVP fluorophore in the presence of GNPs is useful for optoelectronic devices and biosensors.

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

    NASA Astrophysics Data System (ADS)

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

    2002-03-01

    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.

  15. Aligned Electrospun Polyvinyl Pyrrolidone/Poly ɛ-Caprolactone Blend Nanofiber Mats for Tissue Engineering

    NASA Astrophysics Data System (ADS)

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2016-02-01

    Electrospun nanofibrous materials are widely used in medical applications such as tissue engineering scaffolds, wound dressing material and drug delivery carriers. For tissue engineering scaffolds, the structure of the nanofiber is similar to extracellular matrix (ECM) which promotes the cell growth and proliferation. In the present study, the aligned nanofiber mats of polyvinyl pyrrolidone (PVP) blended poly ɛ-caprolactone (PCL) was successfully generated using electrospinning technique. The morphology of PVP/PCL nanofiber mats were characterized by scanning electron microspore (SEM). The chemical and crystalline structure of PVP/PCL nanofiber mats were analyzed using Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffactometer (PXRD). The water contact angle of mats was investigated. Cell culture studies using normal human fibroblasts (NHF) were performed to assess cell morphology, cell alignment and cell proliferation. The results indicated that the fiber were in nanometer range. The PVP/PCL was well dispersed in nanofiber mats and was in amorphous form. The water contact angle of PVP/PCL nanofiber mats was lower than PCL nanofiber mats. The PVP/PCL nanofiber mats exhibited good biocompatibility with NHF cells. In summary, the PVP/PCL nanofiber mats had potential to be used in tissue engineering and regenerative medicine.

  16. Intermolecular Interactions and the Release Pattern of Electrospun Curcumin-Polyvinyl(pyrrolidone) Fiber.

    PubMed

    Rahma, Annisa; Munir, Muhammad Miftahul; Khairurrijal; Prasetyo, Anton; Suendo, Veinardi; Rachmawati, Heni

    2016-01-01

    An electrospun fiber of polyvinyl(pyrrolidone) (PVP)-Tween 20 (T20) with curcumin as the encapsulated drug has been developed. A study of intermolecular interactions was performed using Raman spectroscopy, Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The Raman and FT-IR studies showed that curcumin preferrably interacted with T20 and altered PVP chain packing, as supported by XRD and physical stability data. The hydroxyl stretching band in PVP shifted to a lower wavenumber with higher intenstity in the presence of curcumin and PVP, indicating that hydrogen bond formation is more intense in a curcumin or curcumin-T20 containing fiber. The thermal pattern of the fiber did not indicate phase separation. The conversion of curcumin into an amorphous state was confirmed by XRD analysis. An in vitro release study in phosphate buffer pH 6.8 showed that intermolecular interactions between each material influenced the drug release rate. However, low porosity was found to limit the hydrogen bond-mediated release.

  17. Fabrication of porous chitosan-polyvinyl pyrrolidone scaffolds from a quaternary system via phase separation.

    PubMed

    Lim, Jin Ik; Im, Heejung; Lee, Woo-Kul

    2015-01-01

    Three-dimensional porous chitosan-polyvinyl pyrrolidone (PVP) scaffolds were fabricated for tissue engineering applications via liquid-liquid or liquid-solid phase separation. A mixture of an acidic aqueous solution with butanol as a non-solvent and a chitosan-PVP quaternary system were freeze-dried. We then studied the homogenous open pore structure and the minute pore distribution in order to improve the mass transfer and cell seeding efficiency while also obtaining the optimal ratio of PVP to provide high interconnectivity and to improve the open-pore structure. The properties of the porous chitosan-PVP scaffolds - including the microstructure, chemical release, water absorption properties, and cell proliferation tests were studied - and the results were compared against those obtained from conventional scaffolds. chitosan-PVP scaffolds with a porosity of over 70% were obtained, and the pore morphology on the surface and within the porous scaffolds showed the presence of homogenous open pores with excellent interconnectivity. As the PVP content increased, main pores (50-100 μm) and minute pores (4-10 μm) could be clearly observed. Also, the porous scaffold showed an improved efficiency for cell adhesion after the cells were cultured for 4 h. After 72 h, the cultured cells presented an increase in the cell proliferation and on the porous scaffolds. These results strongly suggest that the porous chitosan-PVP scaffolds can be widely used in tissue engineering, including for biopatches and artificial skin applications.

  18. Glass transition and dynamics of poly(vinyl pyrrolidone)-water mixture

    NASA Astrophysics Data System (ADS)

    Miyara, M.; Sakuramatsu, Y.; Sasaki, K.; Kita, R.; Shinyashiki, N.; Yagihara, S.

    2013-02-01

    Broadband dielectric measurements of poly(vinyl pyrrolidone) (PVP)-water mixture were performed in a frequency range of 10 mHz - 50 GHz and at temperatures between 118 K and 318 K. The relaxation processes caused by the reorientational motion of water molecules (h-process) and the local chain motion of PVP (m-process) were observed without crystallization of water. The relaxation time of the m-process, τm, obeys the Vogel-Fulcher law, and the glass transition temperature, Tg, of PVP in the mixture, at which τm being 100 s is 237 K. The relaxation time of the h-process, τh, obeys the Vogel-Fulcher law above Tg = 237 K, and it turns to obey the Arrhenius law below Tg. The relaxation strength of the m-process, Δɛm, increases with decreasing temperature. The relaxation strength of the h-process, Δɛh, increases with decreasing temperature above the crossover temperature, TC (TC = 272 K), and it turns to be almost constant below TC. The temperature dependences of τm and τh are the same as those of the α- and the ν-processes observed in various kinds of water mixtures. In contrast, the temperature dependence of Δɛh is different from that observed in various kinds of water mixtures. The characteristic property of Δɛh could be related to the highest Tg of neat PVP in those of the solutes of other water mixtures.

  19. Radioimmunoassay of salivary cyclosporine with use of /sup 125/I-labeled cyclosporine

    SciTech Connect

    Coates, J.E.; Lam, S.F.; McGaw, W.T.

    1988-08-01

    We prepared /sup 125/I-labeled cyclosporine (/sup 125/I-CS) by modifying the procedure of Mahoney and Orf and characterized it with regards to maximal immunoreactivity (greater than 90%), trichloroacetic acid precipitability (greater than 90%), and stability (90% immunoreactive after five half-lives of /sup 125/I). For a particular preparation of /sup 125/I-CS, we estimated its immunoreaction concentration (50 pmol/L) and the equilibrium constant for its reaction with Sandoz polyclonal antiserum (K = 3.9 X 10(9) L/mol). By substituting /sup 125/I-CS as tracer in the Sandoz radioimmunoassay and by modifying other aspects of the assay, we developed a procedure that is sufficiently sensitive (0.34 micrograms/L) to allow measurement of trough (lowest inter-dose) cyclosporine concentrations in parotid saliva. Of 38 kidney-transplant patients, 35 had measurable concentrations in saliva (mean 8.3, SD 5.2 micrograms/L), and these correlated moderately with paired serum concentrations (r = 0.68, P less than 0.001). We believe that measurement of salivary cyclosporine may offer a simple way of estimating the free fraction of the drug in serum or plasma.

  20. Absorption of enzymatically active sup 125 I-labeled bovine milk xanthine oxidase fed to rabbits

    SciTech Connect

    Rzucidlo, S.J. ); Zikakis, J.P. )

    1990-05-01

    Rabbits fed a regular laboratory diet supplemented with a high-fat milk containing xanthine oxidase (XO) were studied to determine the presence of active XO in the blood. A pilot feeding study, where rabbits consumed a high-fat diet containing xanthine oxidase, showed a correlation between dairy food consumption and XO activity in the blood. Antibody to dietary XO was also found. In a second study, rabbits were fed ad libitum the high-fat milk and blood serum samples were tested weekly for XO activity. No elevation in serum XO activity was found. A third study showed that serum XO activity was increased when rabbits were force fed the high-fat milk. The final study consisted of force feeding {sup 125}I-labeled XO to one rabbit to ascertain whether the observed increase in serum XO was due to dietary or endogenous XO. Isoelectric focusing of sera collected from the test rabbit strongly suggested that at least a portion of the serum XO contained the radioactive label. This is the first direct evidence showing the uptake of dietary active XO from the gut.

  1. A sensitive radioimmunoassay for corticotropin using a fully biologically active 125I-labeled ligand

    SciTech Connect

    Buckley, D.I.; Hagman, J.; Ramachandran, J.

    1981-07-01

    The human corticotropin (ACTH) analog, Phe2,Nle4-ACTH-(1-38) was iodinated by the chloramine-T procedure and the product was purified by reverse phase high performance liquid chromatography. The specific radioactivity of (/sup 125/I)Tyr23,Phe2,Nle4-ACTH-(1-38) was determined by comparing the antiserum binding curves of the iodinated peptide and (3H)ACTH of known specific activity. This method gave a value of 1800 +/- 75 Ci/mmol, which is close to the theoretical radioactivity expected for the introduction of a single /sup 125/I atom into the peptide. (/sup 125/I)Tyr23,Phe2,Nle4-ACTH-(1-38) was as potent as ACTH in stimulating corticosterone production in isolated rat adrenocortical cells. The concentrations for half-maximal steroidogenesis were 36.5 +/- 6.1 pM for the /sup 125/I derivative and 37.6 +/- 6.7 pM for ACTH. By the use of this /sup 125/I-labeled ligand, a highly sensitive RIA capable of detecting 1 pg ACTH was developed.l The antiserum employed in this study appeared to be directed against residues 11-13 of ACTH.

  2. Mixed poly(vinyl pyrrolidone)-based drug-loaded nanomicelles shows enhanced efficacy against pancreatic cancer cell lines.

    PubMed

    Veeren, Anisha; Bhaw-Luximon, Archana; Mukhopadhyay, Debabrata; Jhurry, Dhanjay

    2017-03-18

    We report in this paper on the enhanced efficacy of a physical mixture of two single anti-cancer loaded nanomicelles against PANC-1 and BxPC-3. Poly(vinyl pyrrolidone-b-polycaprolactone) (PVP-b-PCL) and poly(vinyl pyrrolidone-b-poly(dioxanone-co-methyl dioxanone)) (PVP-b-P(DX-co-MeDX)) were synthesized and successfully loaded with various anti-cancer drugs - gemcitabine (GEM), doxorubicin.HCl (DOX.HCl), doxorubicin.NH2 (DOX), 5-fluorouracil (5-FU) and paclitaxel (PTX). Spherical micelles of size 160-477 nm were obtained as characterized by DLS while sizes determined by TEM were in the range 140-250 nm. The hydrophobic drugs had a higher loading percentage efficiency compared to hydrophilic drugs in the trend PTX>DOX>5-FU>GEM>DOX.HCl whereas the drug release pattern followed the reverse trend in accordance with decreased polymer-drug interaction as quantified by the binding constant and micellar drug location. Cellular uptake studies showed that nanomicelles are taken up by pancreatic cancer cells into the cytoplasm and nucleus. The free nanomicelles were confirmed to be non-cytotoxic. A physical mixture of GEM loaded micelles and DOX.HCl loaded micelles of comparable size showed significantly higher cytotoxicity than either the free drug mixture or the individual single drug loaded micelles as confirmed by their IC50 values.

  3. Acetylation of chromosome squashes of Drosophila melanogaster decreases the background in autoradiographs from hybridization with [125I]-labeled RNA.

    PubMed

    Hayashi, S; Gillam, I C; Delaney, A D; Tener, G M

    1978-08-01

    DNA in prepared chromosomes from the larval salivary glands of Drosophila melanogaster was hybridized with [125I]-labeled 5S and tRNA from the same organism. Autoradiography revealed that radioactivity was frequently bound to all regions of the slides, masking labeling of the chromosomes. Acetylation of the preparations before hybridization prevented the formation of this background and revealed the specific chromosomal sites.

  4. An Optimized Protocol for the Efficient Radiolabeling of Gold Nanoparticles by Using a 125I-labeled Azide Prosthetic Group.

    PubMed

    Jeon, Jongho; Shim, Ha Eun; Mushtaq, Sajid; Choi, Mi Hee; Park, Sang Hyun; Choi, Dae Seong; Jang, Beom-Su

    2016-10-10

    Here, we demonstrate a detailed protocol for the radiosynthesis of a (125)I-labeled azide prosthetic group and its application to the efficient radiolabeling of DBCO-group-functionalized gold nanoparticles using a copper-free click reaction. Radioiodination of the stannylated precursor (2) was carried out by using [(125)I]NaI and chloramine T as an oxidant at room temperature for 15 min. After HPLC purification of the crude product, the purified (125)I-labeled azide (1) was obtained with high radiochemical yield (75 ± 10%, n = 8) and excellent radiochemical purity (>99%). For the synthesis of radiolabeled 13-nm-sized gold nanoparticles, the DBCO-functionalized gold nanoparticles (3) were prepared by using a thiolated polyethylene glycol polymer. A copper-free click reaction between 1 and 3 gave the (125)I-labeled gold nanoparticles (4) with more than 95% of radiochemical yield as determined by radio-thin-layer chromatography (radio-TLC). These results clearly indicate that the present radiolabeling method using a strain-promoted copper-free click reaction will be useful for the efficient and convenient radiolabeling of DBCO-group-containing nanomaterials.

  5. 125I-labeled anti-bFGF monoclonal antibody inhibits growth of hepatocellular carcinoma

    PubMed Central

    Hu, Peng-Hui; Pan, Lan-Hong; Wong, Patrick Ting-Yat; Chen, Wen-Hui; Yang, Yan-Qing; Wang, Hong; Xiang, Jun-Jian; Xu, Meng

    2016-01-01

    AIM: To investigate the inhibitory efficacy of 125I-labeled anti-basic fibroblast growth factor (bFGF) monoclonal antibody (mAb) in hepatocellular carcinoma (HCC). METHODS: bFGF mAb was prepared by using the 1G9B9 hybridoma cell line with hybridization technology and extracted from ascites fluid through a Protein G Sepharose affinity column. After labeling with 125I through the chloramine-T method, bFGF mAb was further purified by a Sephadex G-25 column. Gamma radiation counter GC-1200 detected radioactivity of 125I-bFGF mAb. The murine H22 HCC xenograft model was established and randomized to interventions with control (phosphate-buffered saline), 125I-bFGF mAb, 125I plus bFGF mAb, bFGF mAb, or 125I. The ratios of tumor inhibition were then calculated. Expression of bFGF, fibroblast growth factor receptor (FGFR), platelet-derived growth factor, and vascular endothelial growth factor (VEGF) mRNA was determined by quantitative reverse transcriptase real-time polymerase chain reaction. RESULTS: The purified bFGF mAb solution was 8.145 mg/mL with a titer of 1:2560000 and was stored at -20 °C. After coupling, 125I-bFGF mAb was used at a 1: 1280000 dilution, stored at 4 °C, and its specific radioactivity was 37 MBq/mg. The corresponding tumor weight in the control, 125I, bFGF mAb, 125I plus bFGF mAb, and 125I-bFGF mAb groups was 1.88 ± 0.25, 1.625 ± 0.21, 1.5 ± 0.18, 1.41 ± 0.16, and 0.98 ± 0.11 g, respectively. The tumor inhibition ratio in the 125I, bFGF mAb, 125I plus bFGF mAb, and 125I-bFGF mAb groups was 13.6%, 20.2%, 25.1%, and 47.9%, respectively. Growth of HCC xenografts was inhibited significantly more in the 125I-bFGF mAb group than in the other groups (P < 0.05). Expression of bFGF and FGFR mRNA in the 125I-bFGF mAb group was significantly decreased in comparison with other groups (P < 0.05). Groups under interventions revealed increased expression of VEGF mRNA (except for 125I group) compared with the control group. CONCLUSION: 125I-bFGF m

  6. Selective light emission in nonbonding electron transitions in poly(vinyl pyrrolidone) molecules on spin-coating in thin layers.

    PubMed

    Mishra, A; Ram, S

    2009-12-24

    It is shown that polymer molecules of poly(vinyl pyrrolidone) (PVP) rearranged in thin layers present surface-enhanced light emission in selective bands over a wide 260-860 nm range of spectrum. Four bands occur in spin-coated films by a dilute solution in water at 288, 395, 560, and 760 nm upon irradiating with an ultraviolet 200-250 nm light. The second and third bands are strong by contributing 82% intensity of the spectrum. Randomly dispersed PVP molecules in solution exhibit a single band (broad) at 425 nm {pi(0) <-- n(1)pi(2)* transition in the nonbonding electrons n(1) in the C=O (2s(2)p(4)) group of pyrrolidone ring} and a harmonic band 650-860 nm (weak) of roughly twice its wavelength. In films, this band is split up into two well-separated pi(0) <-- n(1)pi(2)* (395 nm) and pi(0) <-- n(2)pi(1)* (560 nm) bands. Localized nonbonding electrons n(2) of the C-N (2s(2)p(3)) moiety of pyrrolidone ring excite and emit part of the energy in the pi(0) <-- n(2)pi(1)* transition with as much intensity as in the pi(0) <-- n(1)pi(2)* band. Localization of n(1) and n(2) electrons on molecular layers of films favors the resonance >N-C=O structure with three C=O stretching bands 1615, 1635, and 1665 cm(-1) against a single band 1638 cm(-1) in randomly dispersed molecules (solution). The C-N stretching frequency is decreased by 30 cm(-1). Results are useful for molecular designing of optical films for down-energy conversion, optical switching, and biological sensors.

  7. Inquiring the mechanism of formation, encapsulation, and stabilization of gold nanoparticles by poly(vinyl pyrrolidone) molecules in 1-butanol

    NASA Astrophysics Data System (ADS)

    Behera, M.; Ram, S.

    2013-02-01

    We present a plausible mechanism of formation, encapsulation, and stabilization of gold nanoparticles (GNPs) in presence of poly(vinyl pyrrolidone) (PVP) in 1-butanol in support of UV-visible, Raman, Fourier transform infrared spectroscopy (FTIR), zetapotential, X-ray photoelectron spectrum (XPS), and transmission electron microscopy. A surface plasmon resonance band at 533 nm in the UV-visible spectrum reveals formation of ~20 nm spherical GNPs in the non-hydrocolloid. In the FTIR spectrum, selective enhancement in the intensity of C-H stretching and red-shift in the C=O band suggests that PVP encapsulate GNP by an interaction between PVP and GNP that occurs via O-atom of pyrrolidone ring. Raman and XPS spectrum well supports the findings of FTIR spectrum. Zeta potential of -15.22 mV at 7.5 pH found in PVP-capped GNP strongly recommends the role of electrosteric effect towards the observed colloidal stability. Microscopic image demonstrates a thin coating of amorphous PVP layer around GNPs in a core-shell structure. Probing the mechanism of formation, encapsulation, and stabilization of GNP could provide essential information for development of bimetallic NPs for catalytic applications.

  8. Multi-stage Mass Spectrometry of Poly(vinyl pyrrolidone) and Its Vinyl Succinimide Copolymer Formed upon Exposure to Sodium Hypochlorite

    PubMed Central

    Fouquet, Thierry; Torimura, Masaki; Sato, Hiroaki

    2016-01-01

    The degradation routes of poly(vinyl pyrrolidone) (PVP) exposed to sodium hypochlorite (bleach) have been previously investigated using chemical analyses such as infrared spectroscopy. So far, no reports have proposed mass spectrometry (MS) as an alternative tool despite its capability to provide molecular and structural information using its single stage electrospray (ESI) or matrix assisted laser desorption ionization (MALDI) and multi stage (MSn) configurations, respectively. The present study thus reports on the characterization of PVP after its exposure to bleach by high resolution MALDI spiralTOF-MS and Kendrick mass defect analysis providing clues as to the formation of a vinyl pyrrolidone/vinyl succinimide copolymeric degradation product. A thorough investigation of the fragmentation pathways of PVP adducted with sodium and proton allows one main route to be described—namely the release of the pyrrolidone pendant group in a charge remote and charge driven mechanism, respectively. Extrapolating this fragmentation pathway, the oxidation of vinyl pyrrolidone into vinyl succinimide hypothesized from the single stage MS is validated by the detection of an alternative succinimide neutral loss in lieu of the pyrrolidone release in the ESI-MSn spectra of the aged PVP sample. It constitutes an example of application of multi-stage mass spectrometry for the characterization of the degradation of polymeric samples at a molecular level. PMID:27800293

  9. Polyvinyl pyrrolidone capped fluorescent anthracene nanoparticles for sensing fluorescein sodium in aqueous solution and analytical application for ophthalmic samples.

    PubMed

    Bhopate, Dhanaji P; Mahajan, Prasad G; Garadkar, Kalyanrao M; Kolekar, Govind B; Patil, Shivajirao R

    2015-11-01

    Based on the known complexation ability between polyvinyl pyrrolidone (PVP) and fluorescein sodium (FL Na(+)), fluorescent PVP capped anthracene nanoparticles (PVP-ANPs) were prepared using a reprecipitation method for detection of fluorescein in aqueous solution using the fluorescence resonance energy transfer (FRET) approach. A dynamic light scattering histogram of PVP-ANPs showed narrower particle size distribution and the average particle size was 15 nm. The aggregation-induced enhanced emission (AIEE) of PVP-ANPs was red shifted from its monomer by 1087.22 cm(-1). The maximum emission was seen to occur at 420 nm. The presence of FL Na(+) in the vicinity of PVP-ANPs quenched the fluorescence of PVP-ANPs because of its adsorption on the surface of PVP-ANPs in aqueous suspension. The FL Na(+) and PVP-ANPs were brought close enough, typically to 7.89 nm, which was less than the distance of 10 nm that is required between the energy donor-acceptor molecule for efficient FRET. The quenching results fit into the Stern-Volmer relationship even at temperatures greater than ambient temperatures. The thermodynamic parameters determined from FRET results helped to propose binding mechanisms involving hydrophobic and electrostatic molecular interaction. The fluorescence quenching results were used further to develop an analytical method for estimation of fluorescein sodium from ophthalmic samples available commercially in the market.

  10. The effects of shear and particle shape on the physical adsorption of polyvinyl pyrrolidone on carbon nanoparticles

    NASA Astrophysics Data System (ADS)

    Vo, Minh D.; Papavassiliou, Dimitrios V.

    2016-08-01

    The effects of shear and particle shape on the physical adsorption of a polymer (polyvinyl pyrrolidone, PVP) on carbon nanoparticles (CNPs) were studied with dissipative particle dynamics (DPD) methods. It was found that the conformation of the polymer during adsorption and desorption from the nanoparticle can be classified into three possible types, i.e. adsorbed, shear-affected and separated, depending on the magnitude of the shear rate in the flow. Spherical and graphene sheet-shaped particles with adsorbed PVP were manipulated in a Couette flow to determine the threshold shear rates leading to changes in the polymer adsorption state. It was found that the polymer was stably adsorbed under higher shear conditions for graphene sheets. In addition, the end-to-end distance and the radius of gyration of the polymer adsorbate was clearly related to the adsorption state, as the polymer underwent a transition from adsorbed to the separated state when the shear rate increased. The critical shear rate at which the polymer desorbed from the surface could be useful in applications where nanoparticles can be used as a molecular delivery system. The physical adsorption and desorption of the same polymer molecules on a flat surface were also investigated. The desorption of the polymer from the flat surface occurred when the shearing force was stronger than the attraction between the PVP and the surface.

  11. The effects of shear and particle shape on the physical adsorption of polyvinyl pyrrolidone on carbon nanoparticles.

    PubMed

    Vo, Minh D; Papavassiliou, Dimitrios V

    2016-08-12

    The effects of shear and particle shape on the physical adsorption of a polymer (polyvinyl pyrrolidone, PVP) on carbon nanoparticles (CNPs) were studied with dissipative particle dynamics (DPD) methods. It was found that the conformation of the polymer during adsorption and desorption from the nanoparticle can be classified into three possible types, i.e. adsorbed, shear-affected and separated, depending on the magnitude of the shear rate in the flow. Spherical and graphene sheet-shaped particles with adsorbed PVP were manipulated in a Couette flow to determine the threshold shear rates leading to changes in the polymer adsorption state. It was found that the polymer was stably adsorbed under higher shear conditions for graphene sheets. In addition, the end-to-end distance and the radius of gyration of the polymer adsorbate was clearly related to the adsorption state, as the polymer underwent a transition from adsorbed to the separated state when the shear rate increased. The critical shear rate at which the polymer desorbed from the surface could be useful in applications where nanoparticles can be used as a molecular delivery system. The physical adsorption and desorption of the same polymer molecules on a flat surface were also investigated. The desorption of the polymer from the flat surface occurred when the shearing force was stronger than the attraction between the PVP and the surface.

  12. Fabrication of high quality carbonaceous coating on Cu nanoparticle using poly(vinyl pyrrolidone) and its application for oxidation prevention

    NASA Astrophysics Data System (ADS)

    Pyo, Youngjun; Choi, Dahyun; Son, Yeon-Ho; Kang, Suhee; Yoon, Eric H.; Jung, Seung-Boo; Kim, Yongil; Sunyong Lee, Caroline

    2016-05-01

    A novel method of carbonaceous coating on the surface of copper particles was developed through a chemical vapor deposition (CVD) process to prevent the oxidation of copper nanoparticles (CNPs). The types of poly(vinyl pyrrolidone) (PVP) used were K-12 (M W 3,500) and K-30 (M W 45,000). The amounts of PVP used ranged from 10 to 50 wt %. Additionally, processing temperatures of 900 and 875 °C were tested and compared. The optimum CVD process conditions for the carbonaceous coating were as follows: 875 °C processing temperature, 50 wt % K12 PVP solution, and gas conditions of \\text{Ar}:\\text{H}2 = 1:1. The resistivity change in the fabricated copper pattern was confirmed that the initial resistivity value of the ink with a mixing ratio of carbonaceous-coated CNPs to 1-octanethiol-coated CNPs of 4:6 (w/w) maintained its initial resistivity value of 2.93 × 10-7 Ω·m for more than 210 days.

  13. Fabrication and characterization of superparamagnetic poly(vinyl pyrrolidone)/poly(L-lactide)/Fe3O4 electrospun membranes

    NASA Astrophysics Data System (ADS)

    Savva, Ioanna; Constantinou, Demetris; Marinica, Oana; Vasile, Eugeniu; Vekas, Ladislau; Krasia-Christoforou, Theodora

    2014-02-01

    The fabrication of magnetoactive fibrous nanocomposite membranes based on poly(vinyl pyrrolidone) (PVP), poly(L-lactide) (PLLA) and pre-formed oleic acid coated magnetite nanoparticles (OA Fe3O4) is presented. The aforementioned materials have been prepared by means of the electrospinning technique following a single-step fabrication process. The PVP/PLLA/OA Fe3O4 nanocomposite membranes were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that provided information on the fiber diameters as well as on the morphological and dimensional characteristics of the OA Fe3O4 nanoparticles embedded within the fibers. The thermal stability of these materials was evaluated by means of thermal gravimetric analysis (TGA) measurements. Finally, vibrational sample magnetometry (VSM) analysis disclosed superparamagnetic behavior at room temperature. The combination of the hydrophilic, biocompatible and photo-crosslinkable PVP with the biodegradable PLLA and the superparamagnetic OA Fe3O4 nanoparticles within these materials allows for the future development of crosslinked fibrous magnetoactive nanocomposites exhibiting high stability in aqueous solutions, with potential use in biomedical and environmental applications.

  14. Inductive effect of poly(vinyl pyrrolidone) on morphology and photocatalytic performance of Bi2WO6

    NASA Astrophysics Data System (ADS)

    Zhang, Qiang; Chen, Jinxing; Xie, Yunyun; Wang, Mozhen; Ge, Xuewu

    2016-04-01

    Bi2WO6 has great potential applications in the field of photocatalyst due to its excellent visible-light photocatalytic performance. This work studied the detailed morphological evolution of Bi2WO6 particles synthesized in a simple hydrothermal system induced by the stabilizer poly(vinyl pyrrolidone) (PVP). The XRD and HRTEM results show PVP would not change the crystal structure of Bi2WO6, but the distribution of PVP on the initially formed Bi2WO6 nanosheets will induce the crystal growth, resulting in a distinct morphology evolution of Bi2WO6 with the increase of the concentration of PVP. At the same time, with the increase of the molecular weight of PVP, the morphology of Bi2WO6 varied from simple sheet-like (S-BWO) to some complicated morphology, such as flower-like (F-BWO), red blood cell-like (B-BWO), and square-pillar-like (SP-BWO). The photocatalytic performances of Bi2WO6 with various morphologies on the decomposition of RhB under visible light irradiation reveal that S-BWO has the best photocatalytic performance, while SP-BWO has the worst. This work not only gives the explanation of the inductive effect of PVP molecular chains on the morphological formation of Bi2WO6 particles, but also provides the controllable way to the preparation of Bi2WO6 with various morphologies taking advantage of the stabilizer PVP.

  15. Antisolvent precipitation technique: A very promising approach to crystallize curcumin in presence of polyvinyl pyrrolidon for solubility and dissolution enhancement.

    PubMed

    Sadeghi, Fatemeh; Ashofteh, Mohammad; Homayouni, Alireza; Abbaspour, Mohammadreza; Nokhodchi, Ali; Garekani, Hadi Afrasiabi

    2016-11-01

    Curcumin with a vast number of pharmacological activities is a poorly water soluble drug which its oral bioavailability is profoundly limited by its dissolution or solubility in GI tract. Curcumin could be a good anticancer drug if its solubility could be increased. Therefore, the aim of the present study was to increase the dissolution rate of curcumin by employing antisolvent crystallization technique and to investigate the effect of polyvinyl pyrrolidone K30 (PVP) as colloidal particles in crystallization medium on resultant particles. Curcumin was crystalized in the presence of different amounts of PVP by antisolvent crystallization method and their physical mixtures were prepared for comparison purposes. The samples were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FT-IR). The solubility and dissolution of the treated and untreated curcumin were also determined. Antisolvent crystallization of curcumin led to the formation of particles with no definite geometric shape. It was interesting to note that the DSC and XRPD studies indicated the formation of a new polymorph and less crystallinity for particles crystallized in the absence of PVP. However, the crystallized curcumin in the presence of PVP was completely amorphous. All crystalized curcumin samples showed much higher dissolution rate compared to untreated curcumin. The amount of curcumin dissolved within 10 for treated curcumin in the presence of PVP (1:1 curcumin:PVP) was 7 times higher than untreated curcumin and this enhancement in the dissolution for curcumin samples crystallized in the absence of PVP was around 5 times. Overall' the results of this study showed that antisolvent crystallization method in the absence or presence of small amounts of PVP is very efficient in increasing the dissolution rate of curcumin to achieve better efficiency for curcumin.

  16. Polyvinyl pyrrolidone/carrageenan blend hydrogels with nanosilver prepared by gamma radiation for use as an antimicrobial wound dressing.

    PubMed

    Singh, Durgeshwer; Singh, Antaryami; Singh, Rita

    2015-01-01

    Hydrogels were prepared using polyvinyl pyrrolidone (PVP) blended with carrageenan by gamma irradiation at different doses of 25 and 40 kGy. Gel fraction of hydrogels prepared using 10 and 15% PVP in combination with 0.25 and 0.5% carrageenan was evaluated. Based on gel fraction, 15% PVP in combination with 0.25% carrageenan and radiation dose of 25 kGy was selected for the preparation of hydrogels with nanosilver. Radiolytic synthesis of silver nanoparticles within the PVP hydrogel was carried out. The hydrogels with silver nanoparticles were assessed for antimicrobial effectiveness and physical properties of relevance to clinical performance. Fluid handling capacity (FHC) for PVP/carrageenan was 2.35 ± 0.39-6.63 ± 0.63 g/10 cm(2) in 2-24 h. No counts for Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Candida albicans were observed in the presence of hydrogels containing 100 ppm nanosilver after 3-6 h. The release of silver from hydrogels containing 100 ppm nanosilver was 20.42 ± 1.98 ppm/100 cm(2) in 24 h. Hydrogels containing 100 ppm nanosilver with efficient FHC demonstrated potential microbicidal activity (≥3 log10 decrease in CFU/ml) against wound pathogens, P. aeruginosa, S. aureus, E. coli, and C. albicans. PVP/carrageenan hydrogels containing silver nanoparticles can be used as wound dressings to control infection and facilitate the healing process for burns and other skin injuries.

  17. A rapid radioimmunoassay using /sup 125/I-labeled staphylococcal protein A for antibody to varicella-zoster virus

    SciTech Connect

    Richman, D.D.; Cleveland, P.H.; Oxman, M.N.; Zaia, J.A.

    1981-05-01

    A sensitive radioimmunoassay for serum antibody to varicella-zoster virus is described; it uses 125I-labeled staphylococcal protein A and a specially designed immunofiltration apparatus. The assay accurately distinguishes between individuals who are susceptible and those who are immune to infection with varicella-zoster virus. In addition, it can detect passive antibody in recipients of varicella-zoster immune globulin. This radioimmunoassay also detects the heterologous antibody responses that occasionally occur in patients infected with herpes simplex virus, which also have been detected by other antibody assays. The particular advantages of this assay are the use of noninfectious reagents, the speed of execution (less than 3 hr), the requirement for only small quantities of serum (30 microliters), the objectivity of end-point determination, and the capability of screening large numbers of sera. Consequently, this radioimmunoassay is especially useful for the rapid identification of susceptible individuals, which is essential for the appropriate management of patients and hospital personnel after exposure to varicella.

  18. Binding of /sup 125/I-labeled recombinant beta interferon (IFN-beta Ser17) to human cells

    SciTech Connect

    O'Rourke, E.C.; Drummond, R.J.; Creasey, A.A.

    1984-12-01

    The authors investigated the binding of /sup 125/I-labeled beta interferon (IFN-beta Ser17), a nonglycosylated recombinant human fibroblast interferon in which cysteine at position 17 is replaced by serine by site-specific mutagenesis. An optimized chloramine T radiolabeling method produced a highly labeled, fully active /sup 125/I-IFN suitable for these studies. Unlike the case with the chloramine T method, incorporation of a single mole of Bolton-Hunter reagent into a mole of IFN-beta Ser17 led to nearly complete loss of biological activity. /sup 125/I-IFN-beta Ser17, prepared by the chloramine T method, bound specifically to human lymphoblastoid cells (Daudi) with a dissociation constant of 0.24 nM. The number of binding sites per cell was 4,000. In competition assays, unlabeled beta interferons (native, recombinant IFN-beta Cys17, and various preparations of IFN-beta Ser17) equally displaced labeled IFN-beta Ser17 on Daudi cells. Recombinant IFN-alpha-1 displaced /sup 125/I-IFN-beta binding to Daudi cells less efficiently than did unlabeled native or recombinant beta interferon. However, at the concentrations tested, native gamma interferon showed no competition with /sup 125/I-IFN. The results indicate that IFN-beta Ser17 and native IFN-beta posses similar binding properties.

  19. 125I-labeled gonadoliberin and high specific activity and immunoreactivity: method of iodination and rapid separation.

    PubMed

    Sarda, A K; Barnes, M A; Nair, R M

    1980-04-01

    We describe optimum conditions for iodinating gonadoliberin with use of relatively large proportions of Na 125I. Products of the iodination are separated on an anion-exchange resin (Amberlite IRA-400). The 125I-labeled gonadoliberin thus obtained has a high specific activity (1400 to 1590 Ci/g); because of the conditions of iodination, we believe that the predominant species of the labeled decapeptide is the mono-iodinated one. Our separation and purification of the labeled substance on ion-exchange resin is rapid, economical, and less cumbersome than the use of a Biogel P-2 column. There is no adsorption of the labeled hormone onto the resin, as evidenced by analytical recovery studies with tritium-labeled gonadoliberin. Paper-strip chromatoelectrophoresis showed no free Na 125I or radiolabeled damaged peptide fragments after purification on the resin. When antiserum was used at a concentration 32-fold that used in the regular assay procedure, only 4% of the radioactivity remained in the free form, indicating the high immunoreactivity of the labeled hormone.

  20. Immunoassay of 5-methyltetrahydrofolate: use of /sup 125/I-labeled protein A as the tracer molecule for specific antibody

    SciTech Connect

    Langone, J.J.

    1980-05-15

    A sensitive and specific solid-phase radioimmunoassay for 5-methyltetrahydrofolate (5-MTHFA) has been developed. /sup 125/I-Labeled staphylococcal Protein A (/sup 125/I-PA) was used as the tracer molecule for rabbit IgG antibodies bound to 5-MTHFA immobilized on polyacrylamide beads. The dose-dependent inhibition of antibody binding by fluid-phase drug was reflected in decreased binding of /sup 125/I-PA. This inhibition, determined in the presence of known amounts of 5-MTHFA, served as the basis for quantification of 5-MTHFA in test samples. An early bleeding was relatively specific; 4.5 ng 5-MTHFA inhibited immune binding by 50% compared to 7700 ng folinic acid or 1200 ng tetrahydrofolate. Other folic acid analogs, including methotrexate, failed to inhibit significantly. The assay using a later bleeding was more sensitive since 1.6 ng 5-MTHFA gave 50% inhibition (detection limit 0.2 ng), but folinic acid cross-reacted significantly. Absorption with immobilized folinic acid markedly enhanced the specificity of this antiserum and resulted in a 15 to 20% increase in maximum inhibition by 5-MTHFA. The assay could be carried out in the presence of 0.025 ml human serum or urine without affecting the standard curve, and was used to determine levels of 5-MTHFA in serum of drug-treated rabbits.

  1. Direct interaction between the catalytic subunit of the calmodulin-sensitive adenylate cyclase from bovine brain with /sup 125/I-labeled wheat germ agglutinin and /sup 125/I-labeled calmodulin

    SciTech Connect

    Minocherhomjee, A.M.; Selfe, S.; Flowers, N.J.; Storm, D.R.

    1987-07-14

    A calmodulin-sensitive adenylate cyclase has been purified to apparent homogeneity from bovine cerebral cortex using calmodulin-Sepharose followed by forskolin-Sepharose and wheat germ agglutinin-Sepharose. The final product appeared as one major polypeptide of approximately 135,000 daltons on sodium dodecyl sulfate-polyacrylamide gels. This polypeptide was a major component of the protein purified through calmodulin-Sepharose. The catalytic subunit was stimulated 3-4-fold by calmodulin (CaM) with a turnover number greater than 1000 min/sup -1/ and was directly inhibited by adenosine. The catalytic subunit of the enzyme interacted directly with /sup 125/I-CaM on a sodium dodecyl sulfate-polyacrylamide gel overlay system, and this interaction was Ca/sup 2 +/ concentration dependent. In addition, the catalytic subunit was shown to directly bind /sup 125/I-labeled wheat germ agglutinin using a sodium dodecyl sulfate-polyacrylamide gel overlay technique, and N-acetylglucosamine inhibited binding of the lectin to the catalytic subunit. Calmodulin did not inhibit binding of wheat germ agglutinin to the catalytic subunit, and the binding of calmodulin was unaffected by wheat germ agglutinin. These data illustrate that the catalytic subunit of the calmodulin-sensitive adenylate cyclase is a glycoprotein which interacts directly with calmodulin and that adenosine can inhibit the enzyme without intervening receptors or G coupling proteins. It is concluded that the catalytic subunit of adenylate cyclase is a transmembrane protein with a domain accessible from the outer surface of the cell.

  2. /sup 125/I-labeled crosslinking reagent that is hydrophilic, photoactivatable, and cleavable through an azo linkage

    SciTech Connect

    Denny, J.B.; Blobel, G.

    1984-09-01

    A radioactive crosslinking reagent, N-(4-(p-azido-m-(/sup 125/I)iodophenylazo)benzoyl)-3-aminopropyl-N'-oxysulfosuccinimide ester, has been synthesized. The reagent is photoactivatable, water-soluble, cleavable through an azo linkage, and labeled with /sup 125/I at the carrier-free specific activity of 2000 Ci/mmol. Any protein derivatized with the reagent is thus converted into an /sup 125/I-labeled photoaffinity probe. Crosslinks are formed following photolysis with 366-nm light, and cleavage by sodium dithionite results in the donation of radioactivity to the distal partner in crosslinked complexes. The newly labeled proteins are then analyzed by gel electrophoresis and autoradiography. The compound was prepared by iodination of N-(4-(p-aminophenylazo)benzoyl)-3-aminopropionic acid using carrier-free Na/sup 125/I and chloramine-T, followed by azide formation and conversion to the water-soluble sulfosuccinimide ester. As a model system, protein A-Sepharose was derivatized with the reagent under subdued light. Each derivatized protein A molecule contained only one crosslinker. The derivatized protein A-Sepharose was then photolyzed in the presence of human serum and subsequently treated with sodium dithionite. Analysis of the serum by gel electrophoresis revealed that 1.1% of the radioactive label originally present on the protein A-Sepharose was transferred to the heavy chain of IgG, which was the most intensely labeled protein in the gel. The next most intensely labeled protein was IgG light chain, which incorporated radioactivity that was lower by a factor of 3.6 than that of the heavy chain. 36 references, 3 figures.

  3. Rapid method for the preparation of 125I-labelled human growth hormone for receptor studies, using reverse-phase high performance liquid chromatography

    SciTech Connect

    Ilondo, M.M.; Dehart, I.; De Meyts, P.

    1986-01-29

    Human growth hormone was labelled with 125 Iodine by the stoichiometric modification of the chloramine-T method to a specific activity of 50-80 microCi/microgram, and the iodinated mixture was purified by reverse-phase high performance liquid chromatography using a C18 column (SynChropak RP-P) and a linear gradient. Compared with the usual Sephadex G-100 chromatography, HPLC gave a much better separation, with a higher yield and a considerably reduced analysis time (30 min vs 5 h). The (125I)-labelled preparation had normal binding to IM-9 lymphocyte receptors. The maximum bindability of the HPLC-purified preparation approximated 90%, which is the best value so far reported for human growth hormone. It is concluded that HPLC is a fast, convenient and reproducible method for obtaining an improved (125I)-labelled human growth hormone for receptor studies.

  4. Polysulfone hemodiafiltration membranes with enhanced anti-fouling and hemocompatibility modified by poly(vinyl pyrrolidone) via in situ cross-linked polymerization.

    PubMed

    Zhu, Lijing; Song, Haiming; Wang, Jiarong; Xue, Lixin

    2017-05-01

    Poly(vinyl pyrrolidone) (PVP) and its copolymers have been widely employed for the modification of hemodiafiltration membranes due to their excellent hydrophilicity, antifouling and hemocompatibility. However, challenges still remain to simplify the modification procedure and to improve the utilization efficiency. In this paper, antifouling and hemocompatibility polysulfone (PSf) hemodiafiltration membranes were fabricated via in situ cross-linked polymerization of vinyl pyrrolidone (VP) and vinyltriethoxysilane (VTEOS) in PSf solutions and non-solvent induced phase separation (NIPS) technique. The prepared membranes were characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM), which suggested that VP and VTEOS have been cross-linked copolymerized in PSf membranes. The modified PSf membranes with high polymer content showed improved hydrophilicity, ultrafiltration and protein antifouling ability. In addition, the modified PSf membranes showed lower protein adsorption, inhibited platelet adhesion and deformation, prolonged the activated partial thromboplastin time (APTT), prothrombin time (PT), and decreased the content of fibrinogen (FIB) transferring to fibrin, indicating enhanced hemocompatibility. In a word, the present work provides a simple and effective one-step modification method to construct PSf membranes with improved hydrophilicity, antifouling and hemocompatibility.

  5. Monoclonal antibodies to human plasma low-density lipoproteins. I. Enhanced binding of 125I-labeled low-density lipoproteins by combined use of two monoclonal antibodies.

    PubMed

    Mao, S J; Patton, J G; Badimon, J J; Kottke, B A; Alley, M C; Cardin, A D

    1983-11-01

    Four monoclonal antibodies (IgG2b) to human plasma low-density lipoproteins (LDL) have been characterized. The binding affinities of each monoclonal antibody to 125I-labeled LDL were moderately high, ranging from 10(8) to 10(10) L/mol at 4 degrees C, but were reduced by at least 50-70% at 37 degrees C. The maximum binding of each monoclonal antibody was unique, ranging from 20 to 95% of total 125I-labeled LDL, suggesting that LDL particles were immunochemically heterogeneous. One antibody, LP-34, had both high and low binding affinities to LDL. Another, LP-47, exhibited high affinity for isolated LDL, yet reacted poorly with native LDL in plasma, indicating that the conformation of isolated LDL differs from that of native LDL in plasma. Unlike polyclonal serum antibodies, a mixture of four monoclonal antibodies failed to precipitate LDL, but did show a drastic increase in binding to LDL. We found that only two of our monoclonal antibodies were necessary for such synergistic enhancement. We propose that one of the monoclonal antibodies may serve as a catalytic reagent, and discuss the clinical significance of this finding.

  6. Preparation of /sup 125/I-labeled human growth hormone of high quality binding properties endowed with long-term stability

    SciTech Connect

    Biscayart, P.L.; Paladini, A.C.; Vita, N.; Roguin, L.P.

    1989-01-01

    /sup 125/I-labeled human growth hormone (/sup 125/I-labeled.hGH) was prepared by using two variants of the chloramine T labelling procedure and purified by polyacrylamide gel electrophoresis (PAGE) of the reaction mixture. Variant A produced a tracer with high specific activity (100 +/- 10 microCi/microgram), high maximal binding capacity to antibodies (93%) and long-term stability (at least 150 days at -20/degree/C). No diiodinated tyrosil residues could be detected in this tracer. Variant B was devised to obtain higher yields of labeled hormone. The electrophoresis of the iodination mixture revealed two radioactive components with Rm values of 0.49 and 0.55 which result from the iodination of hGH variants preexisting in the starting material. Both tracers had similar specific activities (70 +/- 10 microCi/microgram), high maximal binding capacity to antibodies or receptors (80-100%, after 80 days of their obtention) and high stability (at least 100 days at -20/degree/C). It is concluded that the iododerivatives of hGH obtained by either method are adequate to perform radioimmunoassay and receptor studies and have long-term stability.

  7. On the biological performance of graphene oxide-modified chitosan/polyvinyl pyrrolidone nanocomposite membranes: In vitro and in vivo effects of graphene oxide.

    PubMed

    Mahmoudi, Nafiseh; Simchi, Abdolreza

    2017-01-01

    Nanofibrous structures that mimic the native extracellular matrix and promote cell adhesion have attracted considerable interest for biomedical applications. In this study, GO-modified nanofibrous biopolymers (GO) were prepared by electrospinning blended solutions of chitosan (80vol%), polyvinyl pyrrolidone (15vol%), polyethylene oxide (5vol%) containing GO nanosheets (0-2wt%). It is shown that GO nanosheets significantly change the conductivity and viscosity of highly concentrated chitosan solutions, so that ultrafine and uniform fibers with an average diameter of 60nm are spinnable. The GO-reinforced nanofibers with controlled pore structure exhibit enhanced elastic modulus and tensile strength (150-300%) with a controllable water permeability to meet the required properties of natural skins. Potential use of the GO-modified biocomposites for tissue engineering is demonstrated in mesenchymal stem cell lines extracted from rat's bone marrow. The biocompatibility assay and SEM imaging reveal that the nanofibrous structure promotes the attachment and maintained characteristic cell morphology and viability up to 72h. In-vivo evaluations in rats show that a faster and more efficient wound closure rate (about 33%) are attained for the 1.5% GO nanofibrous membrane as compared with control (sterile gauze sponges).

  8. Regulation of biphasic drug release behavior by graphene oxide in polyvinyl pyrrolidone/poly(ε-caprolactone) core/sheath nanofiber mats.

    PubMed

    Yu, Hui; Yang, Peng; Jia, Yongtang; Zhang, Yumei; Ye, Qiuying; Zeng, Simin

    2016-10-01

    One of the key issues for drug delivery systems is to develop a drug carrier with a time-programmed, biphasic release behavior. Using vancomycin hydrochloride (VAN) as a model drug, polyvinyl pyrrolidone (PVP) blended with graphene oxide (GO) sheets as the core matrix, and poly(ε-caprolactone) (PCL) as the sheath polymer, core/sheath PVP/PCL nanofiber mats were fabricated via a coaxial electrospinning process. We hypothesized that the addition of GO sheets would lead to their molecular interactions with VAN molecules, thereby adjusting the VAN release behavior. Field emission scanning electron microscopy and transmission electron microscopy of the fiber mats revealed their nanofibrous structure and clear core/sheath boundary. Raman analysis demonstrated the presence of GO sheets in the PVP/PCL nanofiber mats. Fourier transform infrared spectroscopy indicated the formation of hydrogen bonds between GO sheets and VAN molecules. In vitro studies showed that the PVP/PCL nanofiber mats were biocompatible, despite the addition of GO sheets, and exhibited typical biphasic drug release profiles, which were tailored by adjusting the content of GO sheets. Furthermore, an antimicrobial test showed different antimicrobial activities of the medicated nanofiber mats, depending on the GO content. Collectively, the results of the present study provide a simple approach to obtaining time-programmed drug release profiles.

  9. Inhibition of /sup 125/I-labeled ristocetin binding to Micrococcus luteus cells by the peptides related to bacterial cell wall mucopeptide precursors: quantitative structure-activity relationships

    SciTech Connect

    Kim, K.H.; Martin, Y.; Otis, E.; Mao, J.

    1989-01-01

    Quantitative structure-activity relationships (QSAR) of N-Ac amino acids, N-Ac dipeptides, and N-Ac tripeptides in inhibition of /sup 125/I-labeled ristocetin binding to Micrococcus luteus cell wall have been developed to probe the details of the binding between ristocetin and N-acetylated peptides. The correlation equations indicate that (1) the binding is stronger for peptides in which the side chain of the C-terminal amino acid has a large molar refractivity (MR) value, (2) the binding is weaker for peptides with polar than for those with nonpolar C-terminal side chains, (3) the N-terminal amino acid in N-Ac dipeptides contributes 12 times that of the C-terminal amino acid to binding affinity, and (4) the interactions between ristocetin and the N-terminal amino acid of N-acetyl tripeptides appear to be much weaker than those with the first two amino acids.

  10. Preliminary Characterization and In Vivo Studies of Structurally Identical 18F- and 125I-Labeled Benzyloxybenzenes for PET/SPECT Imaging of β-Amyloid Plaques

    PubMed Central

    Yang, Yanping; Zhang, Xiaoyang; Cui, Mengchao; Zhang, Jinming; Guo, Zhide; Li, Yesen; Zhang, Xianzhong; Dai, Jiapei; Liu, Boli

    2015-01-01

    With the assistance of molecular docking and 3D-QSAR models established previously, structurally identical 18F- and 125I-labeled benzyloxybenzene derivatives were designed to achieve the early detection of Aβ plaques by PET/SPECT imaging. In competition binding assay, ligands 7a and 12a displayed high binding affinities to Aβ42 aggregates with Ki values of 19.5 nM and 23.9 nM, respectively. Specific plaque labeling was observed on the in vitro autoradiography of brain sections from AD patients and Tg mice. In biodistribution, [125I]7a, [18F]7a, [125I]12a and [18F]12a all exhibited high initial brain uptakes (>5% ID/g at 2 min). [125I]7a and [125I]12a cleared fast from the normal brain regions, while corresponding [18F]7a and [18F]12a showed slow washout rates. Dynamic microPET/CT and microSPECT/CT imaging data in normal ICR mice were in accordance with in vivo biodistribution results. In vivo metabolism results indicated that the different clearance profiles between the structurally identical 18F- and 125I-labeled tracers could be attributed to different biochemical characteristics of the radiometabolites. Radioiodinated benzyloxybenzene derivatives exhibited good in vivo biostability in brain. Ex vivo autoradiography further confirmed the strong in vivo Aβ labeling ability of [125I]7a. These new fluorinated and iodinated benzyloxybenzenes can develop into PET/SPECT dual imaging agents targeting Aβ plaques. PMID:26170205

  11. Multifunctional chitosan/polyvinyl pyrrolidone/45S5 Bioglass® scaffolds for MC3T3-E1 cell stimulation and drug release.

    PubMed

    Yao, Qingqing; Li, Wei; Yu, Shanshan; Ma, Liwei; Jin, Dayong; Boccaccini, Aldo R; Liu, Yong

    2015-11-01

    Novel chitosan-polyvinyl pyrrolidone/45S5 Bioglass® (CS-PVP/BG) scaffolds were prepared via foam replication and chemical cross-linking techniques. The pristine BG, CS-PVP coated BG and genipin cross-linked CS-PVP/BG (G-CS-PVP/BG) scaffolds were synthesized and characterized in terms of chemical composition, physical structure and morphology respectively. Resistance to enzymatic degradation of the scaffold is improved significantly with the use of genipin cross-linked CS-PVP. The bio-effects of scaffolds on MC3T3-E1 osteoblast-like cells were evaluated by studying cell viability, adhesion and proliferation. The CCK-8 assay shows that cell viability on the resulting G-CS-PVP/BG scaffold is improved obviously after cross-linking of genipin. Cell skeleton images exhibit that well-stretched F-actin bundles are obtained on the G-CS-PVP/BG scaffold. SEM results present significant improvement on the cell adhesion and proliferation for cells cultured on the G-CS-PVP/BG scaffold. The drug release performance on the as-synthesized scaffold was studied in a phosphate buffered saline (PBS) solution. Vancomycin is found to be released in burst fashion within 24h from the pristine BG scaffold, however, the release period from the G-CS-PVP/BG scaffold is enhanced to 7days, indicating improved drug release properties of the G-CS-PVP/BG scaffold. Our results suggest that the G-CS-PVP/BG scaffolds possess promising physicochemical properties, sustained drug release capability and good biocompatibility for MC3T3-E1 cells' proliferation and adhesion, suggesting their potential applications in areas such as MC3T3-E1 cell stimulation and bone tissue engineering.

  12. Molecular design of conjugated tumor necrosis factor-alpha: synthesis and characteristics of polyvinyl pyrrolidone modified tumor necrosis factor-alpha.

    PubMed

    Kamada, H; Tsutsumi, Y; Tsunoda, S; Kihira, T; Kaneda, Y; Yamamoto, Y; Nakagawa, S; Horisawa, Y; Mayumi, T

    1999-04-13

    We conjugated tumor necrosis factor-alpha (TNF-alpha) with the synthetic polymeric modifier polyvinyl pyrrolidone (PVP) to facilitate its clinical use for anti-tumor therapy. TNF-alpha was chemically conjugated with the terminal carboxyl-bearing PVP at one end of its main chain, which was radically polymerized via the formation of an amide bond between the lysine amino groups of TNF-alpha and carboxyl group of PVP. In vitro specific bioactivity of PVP-conjugated TNF-alpha (PVP-TNF-alpha) relative to that of native TNF-alpha gradually decreased with increases in the degree of PVP attachment. In contrast, PVP-TNF-alpha in which 40% of TNF-alpha lysine residues were coupled with PVP (MPVP-TNF-alpha) exhibited the highest anti-tumor activity among the conjugated derivatives examined. MPVP-TNF-alpha had more than 200-fold higher anti-tumor efficacy than native TNF-alpha, and the anti-tumor activity of MPVP- TNF-alpha was more than 5-fold stronger than that MPEG- TNF-alpha which had the highest anti-tumor activity among PEG-conjugated TNF-alphas examined. Additionally, a high dose of native TNF-alpha induced toxic side-effects such as body weight reduction, piloerection and tissue inflammation, while no side effects were observed following i.v. administration of MPVP-TNF-alpha. The plasma half-life of MPVP-TNF-alpha (360 min) was about 80 and 3-fold longer than those of native TNF-alpha (4.6 min) and MPEG-TNF-alpha (122 min), respectively. These results suggested that PVP is a useful polymeric modifier for increasing the anti-tumor activity of PVP.

  13. Direct method for detection and characterization of cell surface receptors for insulin by means of 125I-labeled autoantibodies against the insulin receptor.

    PubMed Central

    Jarrett, D B; Roth, J; Kahn, C R; Flier, J S

    1976-01-01

    Autoantibodies directed against the cell surface receptors for insulin are found in some patients with extreme insulin resistance. These antibodies specifically inhibit the binding of insulin to its receptor. A purified IgG fraction from one patient's plasma was labeled with 125I. The 125I-labeled antireceptor antibody, which initially represented about 0.3% of the total 125I-IgG, was enriched by selective adsorption and subsequent elution from cells rich in insulin receptors. The 125I-antireceptor antibody bound to cells and the binding was inhibited by whole plasma and purified IgG from this patient, as well as whole plasma from another patient with autoantibodies to the insulin receptor. Insulins that differed 300-fold in biological potency and affinity inhibited binding of 125I-antireceptor antibody in direct proportion to their ability to bind to the insulin receptor. The binding of 125I-antireceptor antibody was closely correlated with the binding of 125I-insulin over a wide range of receptor concentrations on different cell types. Experimentally induced reduction of the insulin receptor concentration was associated with parallel decreases in the binding of 125I-antireceptor antibody and 125I-insulin. The preparation of 125I-antireceptor antibody with a high specific activity by cytoadsorption and elution has provided a sensitive method for the detection of receptors and autoantibodies to cell surface components. PMID:1069300

  14. Measurement of cyclosporine concentrations in whole blood: HPLC and radioimmunoassay with a specific monoclonal antibody and /sup 3/H- or /sup 125/I-labeled ligand compared

    SciTech Connect

    Wolf, B.A.; Daft, M.C.; Koenig, J.W.; Flye, M.W.; Turk, J.W.; Scott, M.G.

    1989-01-01

    We compared cyclosporine concentrations in whole blood as measured by HPLC and by RIA with a monoclonal antibody specific for cyclosporine with /sup 3/H- or /sup 125/I-labeled cyclosporine ligand. The /sup 3/H-RIA kit slightly underestimated cyclosporine concentrations (greater than 600 micrograms/L) in comparison with HPLC. Over a wide range of concentrations, cyclosporine measured with the /sup 125/I-RIA kit correlated well with HPLC (slope = 0.99, n = 301, r = 0.98), observed for samples from recipients of kidney, heart, or liver allografts (respective slopes: 1.01, 0.93, and 1.00). The /sup 125/I-RIA standard curve was linear to 1000 micrograms of cyclosporine per liter. Inter- and intra-assay CVs for /sup 125/I-RIA measurements of cyclosporine were less than or equal to 7%. Evidently, the /sup 125/I-RIA kit involving a monoclonal antibody specific for cyclosporine is equivalent to the HPLC assay and can replace it for therapeutic drug monitoring of cyclosporine therapy.

  15. Lymphatic flow in humans as indicated by the clearance of /sup 125/I-labeled albumin from the subcutaneous tissue of the leg

    SciTech Connect

    Fernandez, M.J.; Davies, W.T.; Owen, G.M.; Tyler, A.

    1983-08-01

    Since the removal of albumin from the extracellular space and its return to the vascular compartment is the essential function of the lymphatic system, the rate at which it is removed from the interstitial tissue may be regarded as a means of estimating lymphatic efficiency. An objective measure of lymphatic function can be obtained by monitoring the rate of clearance following injection of /sup 125/I-labeled albumin (RIHSA) from the subcutaneous tissue of a limb. The clearance of /sup 125/I-RIHSA from lower limb was monitored in a group of patients with normal limbs, patients with unilateral edema due to deep vein thrombosis, and patients with bilateral edema due to hypoproteinemia. The mean T1/2 in normal legs was 32.7 hr, compared to 23.7 hr in edematous limbs due to deep vein thrombosis and 19.4 in edematous limbs due to hypoproteinemia. There is a clear-cut difference in clearance rate between edematous and nonedematous limbs. This suggests that lymphatic flow is increased in edema due to venous obstruction and hypoproteinemia.

  16. Binding of /sup 125/I-labeled endotoxin to bovine, canine, and equine platelets and endotoxin-induced agglutination of canine platelets

    SciTech Connect

    Meyers, K.M.; Boehme, M.; Inbar, O.

    1982-10-01

    Endotoxin from Escherichia coli O127:B8, Salmonella abortus-equi and S minnesota induced clumping of some canine platelets (PLT) at a final endotoxin concentration of 1 microgram/ml. Endotoxin-induced clumping of canine PLT was independent of PLT energy-requiring processes, because clumping was observed with canine PLT incubated with 2-deoxy-D-glucose and antimycin A. The PLT responded to adenosine diphosphate before, but not after, incubation with the metabolic inhibitors. Endotoxin induced a slight and inconsistant clumping of bovine and equine PLT at high (mg/ml) endotoxin concentration. High-affinity binding sites could not be demonstrated on canine, bovine, and equine PLT, using /sup 125/I-labeled E coli O127:B8 endotoxin. Nonspecific binding was observed and appeared to be due primarily to an extraneous coat on the PLT surface that was removed by gel filtration. The endotoxin that was bound to PLT did not appear to modify PLT function. An attempt to identify plasma proteins that bound physiologically relevant amounts of endotoxin was not successful. The significance of the endotoxin-induced clumping or lack of it on the pathophysiology of endotoxemia is discussed.

  17. Studies on gonococcus infection. XVIII. 125I-labeled peptide mapping of the major protein of the gonococcal cell wall outer membrane.

    PubMed Central

    Swanson, J

    1979-01-01

    The major outer membrane proteins from 10 gonococcal strains were examined after 125I-labeling of the proteins as single bands resolved by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. These 125I-proteins were then treated with either trypsin or alpha-chymotrypsin, and the resultant 125I-peptides were visualized by autoradiography after two-dimensional electrophoretic and chromatographic separation on thin-layer cellulose sheets. Several 125I-peptides were present in all the major outer membrane proteins examined. The presence and absence of additional 125I-peptides segregated the major proteins into two pattern groups. One group consisted of major outer membranes with molecular weights of 34,000 or 33,000; major proteins with molecular weights of 32,000 constituted the other group. Two beta-lactamase-producing gonococcal isolates were examined. Their major outer membrane proteins were identical in apparent molecular weights and alpha-chymotryptic 125I-peptide fingerprints; these proteins contained 125I-peptides not found in other gonococcal major proteins. No 125I-peptide differences were found among the major outer membrane proteins of strain F62 gonococci that exhibited differences in piliation and/or colony opacity characteristics. Images PMID:110681

  18. Macrophage function as studied by the clearance of /sup 125/I-labeled polyvinylpyrrolidone in iron-deficient and iron-replete mice

    SciTech Connect

    Kuvibidila, S.; Wade, S.

    1987-01-01

    This study evaluated the effects of iron deficiency and iron repletion on in vivo macrophage function determined by the clearance of /sup 125/I-labeled polyvinylpyrrolidone (PVP). Two experiments were done. There were four groups of C57BL/6 female mice in experiment 1: the iron-deficient (ID), pair-fed (PF), control (C) and the high iron (HI) groups. In experiment 2, there were three ID groups (severe to moderate anemia), three PF, one C and four ID groups that were fed adequate iron for 14 (R-14), 7 (R-7), 3 (R-3) days before or on the day of PVP injection (R-0). The overall rate of PVP clearance from blood was lower in ID than in C or PF groups. This clearance is expressed by a constant, K, calculated from natural log (ln) of the cpm and the time postadministration of PVP that blood was drawn. The theoretical individual macrophages function (alpha PVP), derived from K and the weights of body, spleen and liver, was also lower in ID than in C or PF groups. The impairment was most severe with the most severe iron deficiency. Repletion for 7 to 15 d before PVP administration resulted in a partial correction of the clearance. Moderate undernutrition in the PF group had no effect.

  19. Biological Effects of Irradiating Hepatocellular Carcinoma Cells by Internal Exposure with 125I-Labeled 5-Iodo-2′-Deoxyuridine-Chitosan Drug Loading Nanoparticles

    PubMed Central

    Zhu, Ran; Wan, Jianmei; Jiang, Bo; Zhou, Dayong; Song, Miaoli

    2014-01-01

    Abstract In this study, the authors evaluate the biological effects of irradiation of hepatocellular carcinoma cells by internal exposure with 125I-labeled 5-iodo-2′-deoxyuridine (125I-UdR)-chitosan drug loading nanoparticles (125I-UdR-CS-DLN). The authors observed that accumulation of nanoparticles was significantly (p<0.05) higher in hepatocellular carcinoma cells HepG2 than normal liver cells HL-7702 after treated with 125I-UdR-CS-DLN for 30 minutes. Survival of HepG2 cells was significantly lower at 125I-UdR-CS-DLN doses higher than 37 kBq/mL (more significant in the G1 phase and G2/M phase) than the HL-7702 cells. In addition, 125I-UdR-CS-DLN induced a higher level of DNA double-strand breaks than 125I-UdR, and HepG2 cells exhibited a lower level of DNA repair when compared with HL-7702 cells. In vivo animal experiments, TUNEL staining, after targeted treatment, showed that 125I-UdR-CS-DLN induced significant cell apoptosis in rabbit hepatocellular tumors in situ than 125I-UdR infusion at the same dose. In conclusion, hepatocellular carcinoma cells were significantly irradiated with 125I-UdR-CS-DLN compared with 125I-UdR, and 125I-UdR-CS-DLN irradiation enhanced DNA damage, induced liver cancer cell apoptosis, and prevented DNA damage repair. However, evaluating the extent of damage and organ sparing in vivo should also be considered. PMID:25379613

  20. Use of 125I-labeled human serum albumin for quantitation of microvascular permeability in rat skin: reevaluation of an old method for studies on substances with an enhancing effect on microvascular permeability

    SciTech Connect

    Gerdin, B.

    1981-11-01

    A method of determining the leakage of 125I-labeled human serum albumin in the plasma into a standardized area of rat skin to study the effects of intracutaneous application of vasoactive substances on microvascular permeability, was reevaluated. The effect is expressed as a quotient (Q) between the amount of labeled albumin in the test area and that in an area injected with buffer. This calculation is simple and as reliable as more complicated expressions of activity. Within a limited dose range, linear/log dose-response curves can be obtained after application of histamine or bradykinin. Locally injected 125I-labeled human serum albumin is eliminated very slowly from rat skin and determination of the amount of radiolabeled albumin in skin after an intravenous injection therefore represents leakage from the vascular compartments. The potentialities and advantages of this method in pharmacological studies are stressed.

  1. Synthesis and evaluation of an (125)I-labeled azide prosthetic group for efficient and bioorthogonal radiolabeling of cyclooctyne-group containing molecules using copper-free click reaction.

    PubMed

    Choi, Mi Hee; Shim, Ha Eun; Nam, You Ree; Kim, Hye Rim; Kang, Jung Ae; Lee, Dong-Eun; Park, Sang Hyun; Choi, Dae Seong; Jang, Beom-Su; Jeon, Jongho

    2016-02-01

    Herein we report the radiosynthesis of a pyridine derived azide prosthetic group for iodine radioisotope labeling of dibenzocyclooctyne (DBCO) conjugated molecules. The radiolabeling of the stannylated precursor 2 was conducted using [(125)I]NaI and chloramine-T to give (125)I-labeled azide ([(125)I]1) with high radiochemical yield (72±8%, n=4) and radiochemical purity (>99%). Using (125)I-labeled azide ([(125)I]1), cyclic RGD peptide and near infrared fluorescent molecule were efficiently labeled with modest to good radiochemical yields. The biodistribution study and SPECT/CT images showed that [(125)I]1 underwent rapid renal clearance. These results clearly demonstrated that [(125)I]1 could be used as an useful radiotracer for in vivo pre-targeted imaging as well as efficient in vitro radiolabeling of DBCO containing molecules.

  2. Binding characteristics of 125I-labelled human FSH to granulosa cells from Booroola ewes which were homozygous, heterozygous or non-carriers of a major gene(s) influencing their ovulation rate.

    PubMed

    McNatty, K P; Lun, S; Heath, D A; Hudson, N L; O'Keeffe, L E; Henderson, K M

    1989-05-01

    At 37 degrees C 125I-labelled human (h) FSH (NIAMDD-hFSH-I-3) bound rapidly to granulosa cells from Booroola and Romney ewes with 50% maximum binding achieved after 3 min and equilibrium being reached within 45 min, irrespective of whether the cells were obtained from the FF, F+ or ++ Booroola genotypes or from Romney ewes. Binding of 125I-labelled FSH followed second order kinetics and there was no effect of follicle diameter (1-2.5 mm vs greater than or equal to 3 mm). Irrespective of breed, genotype or follicle size, the mean (+/- s.e.m.) calculated association rate constant, (ka) was 7.3 (+/- 0.8) x 10(5) litres mol-1 sec-1 (n = 12). Dissociation of receptor bound 125I-labelled hFSH was less than 5% after 30 min and low but variable (i.e. between 0 and 30%) after 2-6 h irrespective of breed, genotype or follicle size. No gene-specific differences were noted in binding specificity between F+ and ++ genotypes: studies were not performed with cells from FF ewes because of insufficient cells. The binding of 125I-labelled hFSH could be displaced with sheep FSH (NIH-FSH-S16; 10% cross-reaction) and FSH-P (2.5% cross-reaction) but other sheep pituitary hormones and hCG showed little or no cross-reaction (less than or equal to 0.1%). The calculated binding capacities (Bmax) and equilibrium dissociation constants (Kd) for 125I-labelled hFSH binding to granulosa cells did not differ between the Booroola genotypes or between Booroola or Romney follicles of different diameter (i.e. 1-2.5 mm; or greater than or equal to 3 mm). The overall mean +/- s.e.m. (n = 24) Bmax and Kd values were 16.7 +/- 0.8 fm/mg protein (i.e. approximately 800 available receptor binding sites/cell) and 1.1 +/- 0.1 nM respectively. Collectively, these findings suggest that the earlier maturation of follicles in FF or F+ ewes compared to ++ ewes is unlikely to be due to gene-specific differences in the FSH binding characteristics of the granulosa cells.

  3. Pharmacokinetics of internally labeled monoclonal antibodies as a gold standard: comparison of biodistribution of /sup 75/Se-, /sup 111/In-, and /sup 125/I-labeled monoclonal antibodies in osteogenic sarcoma xenografts in nude mice

    SciTech Connect

    Koizumi, M.; Endo, K.; Watanabe, Y.; Saga, T.; Sakahara, H.; Konishi, J.; Yamamuro, T.; Toyama, S.

    1989-04-01

    In order to know the true biodistribution of anti-tumor monoclonal antibodies, three monoclonal antibodies (OST6, OST7, and OST15) against human osteosarcoma and control antibody were internally labeled with 75Se by incubating (75Se)methionine and hybridoma cells. 75Se-labeled monoclonal antibodies were evaluated both in vitro and in vivo using the human osteogenic sarcoma cell line KT005, and the results were compared with those of 125I- and 111In-labeled antibodies. 75Se-, 125I- and 111In-labeled monoclonal antibodies had identical binding activities to KT005 cells, and the immunoreactivity was in the decreasing order of OST6, OST7, and OST15. On the contrary, in vivo tumor uptake (% injected dose/g) of 75Se- and 125I-labeled antibodies assessed using nude mice bearing human osteosarcoma KT005 was in the order of OST7, OST6, and OST15. In the case of 111In, the order was OST6, OST7, and OST15. High liver uptake was similarly seen with 75Se- and 111In-labeled antibodies, whereas 125I-labeled antibodies showed the lowest tumor and liver uptake. These data indicate that tumor targeting of antibody conjugates are not always predictable from cell binding studies due to the difference of blood clearance of labeled antibodies. Furthermore, biodistribution of both 111In- and 125I-labeled antibodies are not identical with internally labeled antibody. Admitting that internally labeled antibody is a ''gold standard'' of biodistribution of monoclonal antibody, high liver uptake of 111In-radiolabeled antibodies may be inherent to antibodies. Little, if any, increase in tumor-to-normal tissue ratios of antibody conjugates will be expected compared to those of 111In-labeled antibodies if stably coupled conjugates are administered i.v.

  4. Specific binding of /sup 125/I-labeled human chorionic gonadotropin to gonadal tissue: comparison of limited-point saturation analyses to Scatchard analyses for determining binding capacities and factors affecting estimates of binding capacity

    SciTech Connect

    Spicer, L.J.; Ireland, J.J.

    1986-07-01

    Experiments were conducted to compare gonadotropin binding capacity calculated from limited-point saturation analyses to those obtained from Scatchard analyses, and to test the effects of membrane purity and source of gonadotropin receptors on determining the maximum percentage of radioiodinated hormone bound to receptors (maximum bindability). One- to four-point saturation analyses gave results comparable to results by Scatchard analyses when examining relative binding capacities of receptors. Crude testicular homogenates had lower estimates of maximum bindability of /sup 125/I-labeled human chorionic gonadotropin than more purified gonadotropin receptor preparations. Under similar preparation techniques, some gonadotropin receptor sources exhibited low maximum bindability.

  5. Comparison of /sup 125/I-labeled and /sup 14/C-Labeled peptides of the major outer membrane protein of Chlamydia Trachomatis Strain L2/434 separated by high-performance liquid chromatography

    SciTech Connect

    Judd, R.C.; Caldwell, H.D.

    1985-01-01

    The objective of this study was to determine if in-gel chloramine-T radioiodination adequately labels OM proteins to allow for accurate and precise structural comparison of these molecules. Therefore, intrinsically /sup 14/C-amino acid labeled proteins and /sup 125/I-labeled proteins were cleaved with two endopeptidic reagents and the peptide fragments separated by HPLC. A comparison of retention times of the fragments, as determined by differential radiation counting, thus indicated whether /sup 125/Ilabeling identified of all the peptide peaks seen in the /sup 14/Clabeled proteins. Results demonstrated that radioiodination yields complete and accurate information about the primary structure of outer membrane proteins. In addition, it permits the use of extremely small amounts of protein allowing for method optimization and multiple separations to insure reproducibility.

  6. Distribution and binding of 18F-labeled and 125I-labeled analogues of ACI-80, a prospective molecular imaging biomarker of disease: a whole hemisphere post mortem autoradiography study in human brains obtained from Alzheimer's disease patients.

    PubMed

    Gulyás, Balázs; Spenger, Christian; Beliczai, Zsuzsa; Gulya, Károly; Kása, Péter; Jahan, Mahabuba; Jia, Zhisheng; Weber, Urs; Pfeifer, Andrea; Muhs, Andreas; Willbold, Dieter; Halldin, Christer

    2012-01-01

    One of the major pathological landmarks of Alzheimer's disease and other neurodegenerative diseases is the presence of amyloid deposits in the brain. The early non-invasive visualization of amyloid is a major objective of recent diagnostic neuroimaging approaches, including positron emission tomography (PET), with an eye on follow-up of disease progression and/or therapy efficacy. The development of molecular imaging biomarkers with binding affinity to amyloid in the brain is therefore in the forefront of imaging biomarker and radiochemistry research. Recently, a dodecamer peptide (amino acid sequence=QSHYRHISPAQV; denominated D1 or ACI-80) was identified as a prospective ligand candidate, binding with high ex vivo affinity to L-Aβ-amyloid (K(d): 0.4 μM). In order to assess the ligand's capacity to visualize amyloid in Alzheimer's disease (AD), two (125)I labeled and three (18)F labeled analogues of the peptide were synthesized and tested in post mortem human autoradiography experiments using whole hemisphere brain slices obtained from deceased AD patients and age matched control subjects. The (18)F-labeled radioligands showed more promising visualization capacity of amyloid that the (125)I-labeled radioligands. In the case of each (18)F radioligands the grey matter uptake in the AD brains was significantly higher than that in control brains. Furthermore, the grey matter: white matter uptake ratio was over ~2, the difference being significant for each (18)F-radioligands. The regional distribution of the uptake of the various radioligands systematically shows a congruent pattern between the high uptake regions and spots in the autoradiographic images and the disease specific signals obtained in adjacent or identical brain slices labeled with histological, immunohistochemical or autoradiographic stains for amyloid deposits or activated astrocytes. The present data, using post mortem human brain autoradiography in whole hemisphere human brains obtained from deceased

  7. Reagents for astatination of biomolecules. 5. Evaluation of hydrazone linkers in (211)At- and (125)I-labeled closo-decaborate(2-) conjugates of Fab' as a means of decreasing kidney retention.

    PubMed

    Wilbur, D Scott; Chyan, Ming-Kuan; Hamlin, Donald K; Nguyen, Holly; Vessella, Robert L

    2011-06-15

    benzoate substituent on the hydrazone was chosen for study with (211)At. That reagent was conjugated with 107-1A4 Fab', then labeled (separately) with (125)I and (211)At. The radiolabeled Fab' conjugates were coinjected into nude mice bearing LNCaP human tumor xenografts, and biodistribution data were obtained at 1, 4, and 24 h pi. Tumor targeting was achieved with both (125)I- and (211)At-labeled Fab', but the (211)At-labeled Fab' reached a higher concentration (25.56 ± 11.20 vs 11.97 ± 1.31%ID/g). Surprisingly, while the (125)I-labeled Fab' was cleared from kidney similar to earlier studies, the (211)At-labeled Fab'was not (i.e., kidney conc. for (125)I vs (211)At; 4 h, 13.14 ± 2.03 ID/g vs 42.28 ± 16.38%D/g; 24 h, 4.23 ± 1.57 ID/g vs 39.52 ± 15.87%ID/g). Since the Fab' conjugate is identical in both cases except for the radionuclide, it seems likely that the difference in tissue clearance seen is due to an effect that (211)At has on either the hydrazone cleavage or on the retention of a metabolite. Results from other studies in our laboratory suggest that the latter case is most likely. The hydrazone linkers tested do not provide the tissue clearance sought for (211)At, so additional hydrazones linkers will be evaluated. However, the results support the use of hydrazone linkers when Fab' conjugated with closo-decaborate(2-) reagents are radioiodinated.

  8. Approaches to sequence analysis of 125I-labeled RNA.

    PubMed Central

    Dickson, E; Pape, L K; Robertson, H D

    1979-01-01

    A method is described for the initial steps of sequence analysis of RNase T1-and pancreatic RN-ase-resistant oligonucleotides of RNA containing cytidylate residues labeled in vitro with 125I. In many cases an oligonucleotide sequence can be deduced from a consideration of (i) its relative position in the two-dimensional fingerprint (with DEAE thin layer homochromatographic second dimension), (ii) its electrophoretic mobility on DEAE paper at pH 1.9, and (iii) identification of its products of further enzymatic digestion by comparison with a set of marker oligonucleotides. Additional methods including analysis of oligonucleotides following chemical blocking of uridylate residues with CMCT and analysis of products of incomplete enzymatic digestion are also discussed. Images PMID:106369

  9. 21 CFR 500.1410 - N-methyl-2-pyrrolidone.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false N-methyl-2-pyrrolidone. 500.1410 Section 500.1410... Used in Food-Producing Animals § 500.1410 N-methyl-2-pyrrolidone. (a) Standard for residues. No residues of n-methyl-2-pyrrolidone may be found in the uncooked edible tissues of cattle as determined by...

  10. 21 CFR 500.1410 - N-methyl-2-pyrrolidone.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false N-methyl-2-pyrrolidone. 500.1410 Section 500.1410... Used in Food-Producing Animals § 500.1410 N-methyl-2-pyrrolidone. (a) Standard for residues. No residues of n-methyl-2-pyrrolidone may be found in the uncooked edible tissues of cattle as determined by...

  11. Metabolism of 125I-labeled lipoproteins by the isolated rat lung

    PubMed Central

    1976-01-01

    The capacity of the isolated perfused rat lung to metabolize the protein moieties of serum lipoproteins was assessed using homologous (rat) and heterologous (human) plasma lipoproteins. The protein and lipid moieties of the plasma lipoproteins were labeled in vivo with Na[125I]. In selected cases the lipoprotein peptides were labeled in vivo with 14C- or 3H-labeled amino acids. Uptake of lipoprotein label during perfusion was monitored by measure of losses in perfusate label and by rises in pulmonary tissue labeling as shown by radioassay and by light and electron microscope radioautography. Lipoprotein degradation was assessed by fractionation of perfusate and lung tissue radioactive material into trichloroacetic acid (TCA)-isoluble, TCA-soluble, and ether-ethanol-soluble fractions. When heparin was included in the perfusion medium, there was selective degradation of the protein portion of very low density lipoprotein (VLDL) in the perfusate and concomitant uptake of radioactive label by the lungs. Low density lipoprotein (LDL)) was neither taken up nor catabolized by the isolated rat lung in the absence or presence of heparin. By light and electron microscopy, the label was localized over the interalveolar septa, predominantly the capillary endothelium. Disappearance of TCA-insoluble radioactivity from the perfusate was associated with the generation of both TCA-soluble iodide and noniodide radioactivity. Greater than 50% of the radioactive label taken up by the lungs was found in the delipidated TCA-insoluble fraction. This study provides in vitro evidence for pulmonary catabolism of VLDL apolipoproteins and uptake of peptide catabolic products of VLDL by the lung. PMID:180034

  12. An (125)I-labeled octavalent peptide fluorescent nanoprobe for tumor-homing imaging in vivo.

    PubMed

    Luo, Haiming; Shi, Jiyun; Jin, Honglin; Fan, Di; Lu, Lisen; Wang, Fan; Zhang, Zhihong

    2012-06-01

    Targeting radiopeptides are promising agents for radio-theranostics. However, in vivo evaluation of their targeting specificity is often obscured by their short biologic half-lives and low binding affinities. Here, we report an approach to efficiently examine targeting radiopeptides with a new class of octavalent peptide fluorescent nanoprobe (Octa-FNP) platform, which is composed of candidate targeting peptides and a tetrameric far-red fluorescent protein (tfRFP) scaffold. To shed light on this process, (125)I-Octa-FNP, (125)I-tfRFP and (125)I-peptide were synthesized, and their targeting functionalities were compared. Both fluorescence imaging and radioactive quantification results confirmed that (125)I-Octa-FNP had a significantly higher cellular binding capability than (125)I-tfRFP. In vivo biodistribution studies show that at 6 h post-injection, (125)I-Octa-FNP had 2-fold and 30-fold higher tumor uptake than that of (125)I-tfRFP and (125)I-peptide, respectively. Moreover, γ-imaging at 24 h post-injection revealed a remarkable accumulation of (125)I-Octa-FNP in the tumor while maintaining an extremely low background contrast, which was further confirmed by immunofluorescence analysis. These data suggested that, as an engineered and multivalent platform, Octa-FNP could enhance the tumor targeting of a designed peptide and provide excellent contrast radioimaging, making it a valuable tool for the evaluation of the targeting ability of specifically designed radiopeptides for cancer theranostics.

  13. Rapid extraction, radioiodination, and in vivo catabolism of 125I-labeled fibrinogen in the horse

    SciTech Connect

    Coyne, C.P.; Hornof, W.J.; Kelly, A.B.; O'Brien, T.R.; DeNardo, S.J.

    1985-12-01

    Two methods were analyzed for the rapid extraction of equine fibrinogen from fresh plasma, using ammonium sulfate-sodium phosphate buffer. Fibrinogen from each of these 2 methods was then radiolabeled with 125I (half-life = 60.2 days, gamma = 35 keV), using monochloroiodine reagent. Mean protein-bound activity was 98.5% and mean clottable radioactivity was 94.1%. Radiolabeled fibrinogen administered IV to 15 horses had an overall mean (+/- SD) plasma half-life of 4.95 +/- 0.44 days.

  14. Radioimmunoassay for serum tobramycin levels using 125I-labeled tobramycin.

    PubMed

    Casley, D J; Atkins, R C; Murphy, G F; Johnston, C I

    1978-10-01

    A radioimmunoassay is described for the measurement of tobramycin in serum or plasma. The technique has advantages over other assay techniques with regard to precision, specificity, sensitivity and rapidity. The radioimmunoassay uses a tracer labelled with 125Iodine. The iodination technique is simple and gives tracer in high yield, at high specific activity and with complete immunological identity to unlabelled tobramycin. There is a significant correlation between the results obtained by this radioimmunoassay and by the disc-plate assay. Such knowledge of serum levels of tobramycin assists the clinician in regulating drug dosage to obtain an optimum therapeutic effect, and yet avoids toxic serum levels.

  15. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 23 2010-07-01 2010-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance....

  16. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 24 2014-07-01 2014-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance. (a)...

  17. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 25 2012-07-01 2012-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance....

  18. 40 CFR 180.1130 - N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 24 2011-07-01 2011-07-01 false N-(n-octyl)-2-pyrrolidone and N-(n... EXEMPTIONS FOR PESTICIDE CHEMICAL RESIDUES IN FOOD Exemptions From Tolerances § 180.1130 N-(n-octyl)-2-pyrrolidone and N-(n-dodecyl)-2-pyrrolidone; exemptions from the requirement of a tolerance....

  19. Photophysical comparative study of amylose and polyvinyle pyrrolidone/single walled carbon nanotubes complex.

    PubMed

    Bonnet, P; Buisson, J P; Nomède Martyr, N; Bizot, H; Buelon, A; Chauvet, O

    2009-10-14

    Progressive addition of hydroxypropylated amylose (AmH), from 0.05 wt% to 4.5 wt%, to single-walled carbon nanotubes (SWNTs) in aqueous surfactant suspensions quenches the intrinsic near Infra-Red fluorescence of semiconducting SWNTs while dispersions obtained with a same amount of polyvinylpyrrolidone (PVP) remain luminescent. Near Infra-Red emission spectroscopy (fluorescence and Raman scattering) of the samples is used to characterize the supramolecular organization of these polymer/SWNT complexes. The SWNTs are found to be wrapped by the PVP chains and not by the AmH chains which rather form AmH/surfactant/SWNTs complexes. In PVP/SWNTs dispersion, the fluorescence line position and intensity are affected by dielectric screening. In the case of AmH/surfactant/SWNTs complex, dielectric screening plays also a role but quenching occurs above about 3 wt% of AmH. We attribute the quenching to the formation of a "composite like" microstructure by opposition to stabilized dispersion.

  20. Inactivation of Ichthyophonus spores using sodium hypochlorite and polyvinyl pyrrolidone iodine

    USGS Publications Warehouse

    Hershberger, P.K.; Pacheco, C.A.; Gregg, J.L.

    2008-01-01

    Chlorine and iodine solutions were effective at inactivating Ichthyophonus spores in vitro. Inactivation in sea water increased directly with halogen concentration and exposure duration, with significant differences (P < 0.05) from controls occurring at all chlorine concentrations and exposure durations tested (1.5-13.3 ppm for 1-60 min) and at most iodine concentrations and exposure durations tested (1.2 ppm for 60 min and 5.9-10.7 ppm for 1-60 min). However, 10-fold reductions in spore viability occurred only after exposure to halogen solutions at higher concentrations and/or longer durations (13 ppm total chlorine for 1-60 min, 5.9 ppm total iodine for 60 min, and 10.7 ppm total iodine for 1-60 min). Inactivation efficacy was greater when halogen solutions were prepared in fresh water, presumably because of combined effects of halogen-induced inactivation and general spore instability in fresh water. The results have practical implications for disinfection and biocontainment in research laboratories and other facilities that handle live Ichthyophonus cultures and/or infected fish.

  1. Intensification of luminescence of Europium-EDTA complex in polyvinyl pyrrolidone films by copper nanoparticles

    NASA Astrophysics Data System (ADS)

    Reisfeld, Renata; Levchenko, Viktoria; Lazarowska, Agata; Mahlik, Sebastian; Grinberg, Marek

    2016-09-01

    Stable copper nanoparticles (CuNPs) were prepared and incorporated into polyvinylpyrrolidone (PVP) films together with pre-prepared complex of europium-ethylenediaminetetraacetic acid (EuEDTA). From the comparison of the excitation spectrum of the complex alone and of the complex in conjunction with CuNPs an increased fluorescence intensity of the complex is observed as the result of interaction of the complex with surface plasmons of copper. This effect is maximal when the extinction band of CuNPs coincides with the absorption maximum of the complex, as much more light reaches the excited state of europium in the complex during the excitation events as the result of light scattered by copper plasmons. An additional band was observed in the excitation spectrum of the complex in co-doped by the CuNPs around 320÷390 nm which we attribute to electron transfer from CuNPs to excited state of europium.

  2. Lotus-leaf-like structured chitosan-polyvinyl pyrrolidone films as an anti-adhesion barrier

    NASA Astrophysics Data System (ADS)

    Lim, Jin Ik; Kang, Min Ji; Lee, Woo-Kul

    2014-11-01

    For postsurgical anti-adhesion barrier applications, lotus-leaf-like structured chitosan-PVP films were prepared using a solution casting method with dodecyltrichloro-immobilized SiO2 nanoparticles. We evaluated whether the lotus-leaf-like structured chitosan-PVP films (L-chitosan-PVP) could be applied as postsurgical anti-adhesion barriers. A recovery test using a tensile strength testing machine and measurement of crystallinity using X-ray diffraction indicated that films with 75% PVP were the optimal composition of the chitosan-PVP films. Also, dodecyltrichloro-immobilized SiO2 nanoparticles were synthesized and sprayed on the film after pretreatment with the instant bio-glue. Analysis of cell adhesion, proliferation, and anti-thrombus efficiency were performed via a WST assay, field emission scanning electron microscopy, and hemacytometry. The contact angle with the lotus-leaf-like surface was of approximately 150°. Furthermore, the L-chitosan-PVP film yielded a lower cell and platelet adhesion rate (around less than 4%) than that yielded by the untreated film. These results indicate that the lotus-leaf-like structure has a unique property and that this novel L-chitosan-PVP film can be applied as a blood/tissue-compatible, biodegradable material for implantable medical devices that need an anti-adhesion barrier.

  3. 78 FR 7275 - 2-Pyrrolidone, 1-Ethenyl-, Polymer With Ethenol; Tolerance Exemption

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-01

    ... AGENCY 40 CFR Part 180 2-Pyrrolidone, 1-Ethenyl-, Polymer With Ethenol; Tolerance Exemption AGENCY... from the requirement of a tolerance for residues of 2-pyrrolidone, 1-ethenyl-, polymer with ethenol... permissible level for residues of 2-pyrrolidone, 1-ethenyl-, polymer with ethenol on food or feed...

  4. 21 CFR 500.1410 - N-methyl-2-pyrrolidone.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Used in Food-Producing Animals § 500.1410 N-methyl-2-pyrrolidone. (a) Standard for residues. No... method from the Communications Staff (HFV-12), Center for Veterinary Medicine, Food and...

  5. Biomonitoring of N-ethyl-2-pyrrolidone in automobile varnishers.

    PubMed

    Koslitz, Stephan; Meier, Swetlana; Schindler, Birgit Karin; Weiss, Tobias; Koch, Holger Martin; Brüning, Thomas; Käfferlein, Heiko Udo

    2014-12-01

    N-alkyl-2-pyrrolidones are important organic solvents for varnishes in industry. This study investigates exposure to N-ethyl-2-pyrrolidone (NEP) in varnishing of hard plastic components in an automobile plant. Two specific biomarkers of exposure, 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI), were analyzed in urine samples of 14 workers. For this purpose, pre-shift, post-shift and next day pre-shift urine samples were collected midweek. Twelve workers performed regular work tasks (loading, wiping and packing), whereas two workers performed special work tasks including cleaning the sprayer system with organic solvents containing N-alkyl-2-pyrrolidones. Spot urine samples of nine non-exposed persons of the same plant served as controls. Median post-shift urinary levels of workers with regular work tasks (5-HNEP: 0.15 mg/L; 2-HESI: 0.19 mg/L) were ∼5-fold higher compared to the controls (0.03 mg/L each). Continuously increasing metabolite levels, from pre-shift via post-shift to pre-shift samples of the following day, were observed in particular for the two workers with the special working tasks. Maximum levels were 31.01 mg/L (5-HNEP) and 8.45 mg/L (2-HESI). No clear trend was evident for workers with regular working tasks. In summary, we were able to show that workers can be exposed to NEP during varnishing tasks in the automobile industry.

  6. Effects of orchidectomy and testosterone replacement on mouse pyrrolidone carboxypeptidase activity in the HPA axis.

    PubMed

    García-López, M J; Martínez-Martos, J M; Mayas, M D; Carrera, M P; Ramírez-Expósito, M J

    2004-03-01

    Pyrrolidone carboxypeptidase, also known as pyroglutamyl aminopeptidase, removes pyroglutamyl terminal residues from biologically active peptides such as thyrotropin-releasing hormone. The aim of the present work was to study the influence of orchidectomy and testosterone replacement on soluble (pyrrolidone carboxypeptidase type I) and membrane-bound (pyrrolidone carboxypeptidase type II) activities in the hypothalamus-pituitary-adrenal axis. Forty male mice (Balb/C) were distributed into five groups: sham-operated controls, orchidectomized, and orchidectomized treated with increasing doses of testosterone in each group (3, 6 and 12 mg/kg). In the hypothalamus, orchidectomy increased pyrrolidone carboxypeptidase type I, whereas the highest dose of testosterone returned this activity to control levels. In the pituitary, neither pyrrolidone carboxypeptidase type I nor type II activities changed after orchidectomy, although both activities increased after administration of testosterone in both cases. On the other hand, orchidectomy increased pyrrolidone carboxypeptidase type I and type II activities in adrenal glands, while testosterone replacement returned it to control levels. These results suggest that testosterone differentially modulates pyrrolidone carboxypeptidase type I and type II activities, and therefore also their endogenous substrate regulation. Thus, the influence of sex hormones in the physiology of the HPA axis through the modulation of the Pyrrolidone carboxypeptidase type I and type II activities is of great importance on stress and neuropathology associated with HPA dysfunction

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  8. Binding of an ( sup 125 I) labelled thromboxane A2/prostaglandin H2 receptor agonist to baboon platelets

    SciTech Connect

    Dorn, G.W. II; De Jesus, A. )

    1989-12-01

    To characterize the thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor on baboon platelets the binding of (125I)BOP was studied. (125I)BOP bound to washed baboon platelets in a saturable manner. Scatchard analysis of binding isotherms revealed a Kd of 1.12 +/- 0.08 nM and a binding capacity of 54 +/- 5 fmoles/10(8) platelets (326 sites/platelet). Several TXA2/PGH2 agonists and antagonists displaced (125I)BOP from its baboon platelet binding site with a rank order of potency similar to human platelets: I-BOP greater than SQ29548 greater than U46619 = I-PTA-OH greater than PTA-OH. I-BOP aggregated washed baboon platelets with an EC50 of 10 +/- 4 nM. The results indicate that (125I)BOP binds to the TXA2/PGH2 receptor on baboon platelets and that this receptor is similar to its human counterpart.

  9. Specific uptake, dissociation, and degradation of /sup 125/I-labeled insulin in isolated turtle (Chrysemys dorbigni) thyroid glands

    SciTech Connect

    Marques, M.; da Silva, R.S.; Turyn, D.; Dellacha, J.M.

    1985-11-01

    Thyroid glands from turtles (Chrysemys dorbigni) pretreated with potassium iodide were incubated with /sup 125/I-insulin in the presence or absence of unlabeled insulin, in order to study its specific uptake. At 24 degrees, the specific uptake reached a plateau at 180 min of incubation. The dose of bovine insulin that inhibited 50% of the /sup 125/I-insulin uptake was 2 micrograms/ml of incubation medium. Most of the radioactive material (71%) extracted from the gland, after 30 min incubation with /sup 125/I-insulin, eluted in the same position as labeled insulin on Sephadex G-50. Only 24% eluted in the salt position. After 240 min incubation, increased amount of radioactivity appeared in the Na/sup 125/I position. When bovine insulin was added together with the labeled hormone, a substantial reduction of radioactivity was observed in the insulin and Na/sup 125/I elution positions. Dissociation studies were performed at 6 degrees in glands preincubated with /sup 125/I-insulin either at 24 or 6 degrees. The percentage of trichloroacetic acid (TCA)-soluble radioactive material in the dissociation medium increased with incubation time at both temperatures. However, the degradation activity was lower at 6 than at 24 degrees. The addition of bovine insulin to the incubation buffer containing /sup 125/I-insulin reduced the radioactive degradation products in the dissociated medium. Chloroquine or bacitracin inhibited the degradation activity. Incubation of thyroid glands with /sup 125/I-hGH or /sup 125/I-BSA showed values of uptake, dissociation, and degradation similar to those experiments in which an excess of bovine insulin was added together with the labeled hormone. Thus, by multiple criteria, such as specific uptake, dissociation, and degradation, the presence of insulin-binding sites in the turtle thyroid gland may be suggested.

  10. /sup 125/I-labeled radioimmunoassay kits for progesterone evaluated for use in an in vitro fertilization program

    SciTech Connect

    Blight, L.F.; White, G.H.

    1983-06-01

    We have evaluated two commercially available /sup 125/I radioimmunoassay kits (Diagnostic Products Corp., DPC; and Radioassay Systems Laboratories, RSL) for measurement of serum or plasma progesterone, to determine their suitability for use in in vitro fertilization programs. Both kits were suitably rapid for program requirements. Results by both were linear with concentration up to 60 nmol/L, and both had acceptable lower detection limits of 0.3 nmol/L. Kit-determined progesterone concentrations (y) for 100 patients' samples correlated well with results by our existing 3H radioimmunoassay method (y . 1.11x + 0.2, r . 0.965 for the DPC kit; y . 1.01x + 1.4, r . 0.974 for the RSL kit). Mean analytical recovery for the RSL kit was 116%, that for the DPC kit, 202%. Within-batch precision, expressed as the mean CV for three concentrations of progesterone, was 6.5% for the RSL kit, and 16.4% for the DPC kit; between-day CV was 8.1% for the RSL kit, 17.7% for the DPC kit. We conclude that the RSL kit provides a rapid, precise, and accurate assay for serum progesterone, suitable for use in a fertilization program, but do not recommend the DPC kit for either this purpose or the more general purpose of tracking menstrual cycles.

  11. Pyrrolidone - a new solvent for the methylation of humic acid

    USGS Publications Warehouse

    Wershaw, R. L.; Pinckney, D.J.; Booker, S.E.

    1975-01-01

    In the past, humic acid has been methylated by suspending it in a solution of diazomethane in diethyl ether, and degrading the partly methylated humic acid to release those parts of the molecule that were methylated. Only small fragments of the molecule have been identified by this technique. In the procedure described here the humic acid is dissolved in 2-pyrrolidone and methylated by the addition of diazomethane in diethyl ether and ethanol to the solution. Because the humic acid is completely dissolved in the reaction medium, disaggregation of the humic acid particles takes place and much more complete methylation is obtained. The methylated products may be fractionated by countercurrent distribution and analyzed by mass spectrometry.

  12. 75 FR 61175 - Polyvinyl Alcohol From Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ... COMMISSION Polyvinyl Alcohol From Taiwan AGENCY: United States International Trade Commission. ACTION... of polyvinyl alcohol, provided for in subheading 3905.30.00 of the Harmonized Tariff Schedule of the... of polyvinyl alcohol from Taiwan are being sold in the United States at less than fair value...

  13. 76 FR 13660 - Polyvinyl Alcohol From Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-14

    ... COMMISSION Polyvinyl Alcohol From Taiwan Determination On the basis of the record \\1\\ developed in the... United States is materially injured by reason of imports from Taiwan of polyvinyl alcohol, provided for... of a preliminary determination by Commerce that imports of polyvinyl alcohol from Taiwan were...

  14. Shock compression of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Neogi, Anupam; Mitra, Nilanjan

    2016-04-01

    This study presents shock compression simulation of atactic polyvinyl chloride (PVC) using ab-initio and classical molecular dynamics. The manuscript also identifies the limits of applicability of classical molecular dynamics based shock compression simulation for PVC. The mechanism of bond dissociation under shock loading and its progression is demonstrated in this manuscript using the density functional theory based molecular dynamics simulations. The rate of dissociation of different bonds at different shock velocities is also presented in this manuscript.

  15. Water vapor absorption into amorphous sucrose-poly(vinyl pyrrolidone) and trehalose-poly(vinyl pyrrolidone) mixtures.

    PubMed

    Zhang, J; Zografi, G

    2001-09-01

    Previous studies from this laboratory suggested that a solution model (Flory-Huggins equation) modified by a free volume model (Vrentas equation) could satisfactorily describe water absorption into an amorphous solid composed of a sugar or a polymer. This paper has extended the studies of single solutes to binary mixtures of trehalose-and sucrose-poly(vinyl pyrrolidone) (trehalose-PVP and sucrose-PVP, respectively) either co-lyophilized or individually lyophilized and then physically mixed. Water vapor absorption isotherms of the binary mixtures were determined at 30 degrees C. Co-lyophilized PVP-sugar mixtures take up essentially the same amount of water as predicted by the weight average of individual isotherms, whereas sugar crystallization is significant retarded in the molecular dispersions. The sugar-PVP interaction, as reflected in the Flory-Huggins chi interaction parameter, was estimated by fitting the high relative pressure (p/p(0)) region of the isotherm, at which the system is in a liquid state, with a three-component Flory-Huggins-type model. The estimated sugar-water PVP-water, and sugar-PVP interaction parameters suggest that the solute-water interactions are not significantly affected by the sugar-PVP interaction; that is, the solute-water interaction parameters in a binary solute system are similar to those in the corresponding single solute systems. Based on these interaction parameters, the sucrose-PVP interaction appears to be stronger than that of trehalose-PVP. Manipulation of the interaction parameters suggest that the water vapor absorption isotherm is not a sensitive indicator of possible sugar-PVP interactions. Density, glass transition temperature, T(g), and the heat capacity change, DeltaC(p), at T(g) were determined to estimate the excess water absorption energy due to the plasticizing effect of water using the structural relaxation model, as described by Vrentas. Results suggest that PVP is a better antiplasticizer for sucrose than for

  16. 77 FR 9528 - Animal Drugs, Feeds, and Related Products; N-Methyl-2-Pyrrolidone; Correction

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-17

    ...-pyrrolidone in edible tissues of cattle. That document contained a universal resource locator (URL) linking to the Agency's Web site that did not reflect the most recent URL. DATES: This correction is effective... tissues of cattle. That document contained a universal resource locator (URL) linking to the Agency's...

  17. Fogging in Polyvinyl Toluene Scintillators

    SciTech Connect

    Cameron, Richard J.; Fritz, Brad G.; Hurlbut, Charles; Kouzes, Richard T.; Ramey, Ashley; Smola, Richard

    2015-02-01

    It has been observed that large polyvinyl toluene (PVT)-based gamma ray detectors can suffer internal “fogging” when exposed to outdoor environmental conditions over long periods of time. When observed, this change results in reduced light collection by photomultiplier tubes connected to the PVT. Investigation of the physical cause of these changes has been explored, and a root cause identified. Water penetration into the PVT from hot, high-humidity conditions results in reversible internal water condensation at room temperature, and permanent micro-fracturing of the PVT at very low environmental temperatures. Mitigation procedures and methods are being investigated.

  18. Polyvinyl alcohol hydrogels for iontohporesis

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    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.

  19. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact..., in accordance with the following prescribed conditions: (a) The polyvinyl alcohol film is...

  20. Characterization and Antimicrobial Activity of N-Methyl-2-pyrrolidone-loaded Ethylene Oxide-Propylene Oxide Block Copolymer Thermosensitive Gel

    PubMed Central

    Phaechamud, T.; Mahadlek, J.; Charoenteeraboon, J.; Choopun, S.

    2012-01-01

    The purpose of this study is to investigate the effects of N-methyl-2-pyrrolidone on the thermosensitive properties of aqueous ethylene oxide-propylene oxide block copolymer (Lutrol® F127) system. Due to the aqueous solubility enhancement and biocompatibility, N-methyl-2-pyrrolidone is an interesting solubilizer for the poorly water soluble drugs to be incorporated in the Lutrol® F127 system. Effect of N-methyl-2-pyrrolidone on physicochemical properties of Lutrol® F127 system was investigated using appearance, pH, gelation, gel melting temperature and rheology. The antimicrobial activity of the thermosensitive N-methyl-2-pyrrolidone gel was also tested. Lower N-methyl-2-pyrrolidone amount (≤30%w/w) could shift the sol-gel transition to a lower temperature but the gel-sol transition was shifted to a higher temperature. Higher N-methyl-2-pyrrolidone (≥40%w/w) could shift both sol-gel and gel-sol transitions of the system to a lower temperature. The amount of N-methyl-2-pyrrolidone >60% w/w could reverse the phase of the Lutrol® F127 system to non-newtonian flow at 4° and Newtonian flow at high temperature. Aqueous Lutrol® F127 system containing N-methyl-2-pyrrolidone exhibited antimicrobial activities against Staphylococcus aureus, Escherichia coli and Candida albicans with the N-methyl-2-pyrrolidone in a dose-dependent manner. PMID:23798774

  1. Simple, rapid /sup 125/I-labeled cyclosporine double antibody/polyethylene glycol radioimmunoassay used in a pediatric cardiac transplant program

    SciTech Connect

    Berk, L.S.; Webb, G.; Imperio, N.C.; Nehlsen-Cannarella, S.L.; Eby, W.C.

    1986-01-01

    We modified the Sandoz cyclosporine radioimmunoassay because of our need for frequent clinical monitoring of cyclosporine drug levels in allo- and xenograft pediatric cardiac transplant patients. With application of a commercially available (/sup 125/I)cyclosporine label in place of (/sup 3/H)cyclosporine and a second antibody/polyethylene glycol (PEG) method of separation in place of charcoal separation, we simplified and enhanced the speed and precision of assay performance. Studies of 140 whole blood samples comparing this new method to the (/sup 3/H)cyclosporine radioimmunoassay (RIA) method of Berk and colleagues yielded a coefficient of correlation of 0.96 (p less than 0.00001) with means of 626 and 667 ng/ml for (/sup 3/H)RIA and (/sup 125/I)RIA, respectively, and a regression equation of y = 28 + 1.02x. The major advantages are that total assay time is reduced to approximately 1 h; (/sup 125/I)cyclosporine label is used, avoiding the problems associated with liquid scintillation counting; and precision is enhanced by separating bound and free fractions with second antibody/PEG. These modifications should provide for greater ease of assay performance and improved clinical utility of cyclosporine monitoring not only in the pediatric but also in the adult transplant patient.

  2. Selective chromosomal damage and cytotoxicity of sup 125 I-labeled monoclonal antibody 17-1a in human cancer cells

    SciTech Connect

    Woo, D.V.; Li, D.; Mattis, J.A.; Steplewski, Z. )

    1989-06-01

    A monoclonal antibody, 17-1a, which reacts with antigen expressed in human colon cancers was radiolabeled in high specific activity with {sup 125}I. The combination of the antibody and this radionuclide was observed to elicit specific cellular damage after being internalized into cells of the SW1116 human colon cancer cell line. The degree of internalization was quantitatively measured and found to increase over time to 49% after a 48-h incubation period. During this period, significant chromosome aberrations were observed in the SW1116 cell line due to the Auger electrons of {sup 125}I. This damage was not observed using Na{sup 125}I, a nonimmunoreactive radiolabeled antibody, or cells which did not contain the requisite antigen. The number of chromosomal aberrations increased with increasing radioactive concentration of {sup 125}I-17-1a. The nuclear damage resulted in specific cellular cytotoxicity and decreased cell survival of SW1116 cells exposed to various concentrations of {sup 125}I-17-1a.

  3. Altered binding of /sup 125/I-labeled calmodulin to a 46. 5-kilodalton protein in skin fibroblasts cultured from patients with cystic fibrosis

    SciTech Connect

    Tallant, E.A.; Wallace, R.W.

    1987-02-01

    The levels of calmodulin and calmodulin-binding proteins have been determined in cultured skin fibroblasts from patients with cystic fibrosis (CF) and age- and sex-matched controls. Calmodulin ranged from 0.20 to 0.76 microgram/mg protein; there was no difference between calmodulin concentration in fibroblasts from CF patients and controls. Calmodulin-binding proteins of 230, 212, 204, 164, 139, 70, 59, 46.5, and 41 kD were identified. A protein with a mobility identical to the 59-kD calmodulin-binding protein was labeled by antiserum against calmodulin-dependent phosphatase. Although Ca/sup 2 +//calmodulin-dependent phosphatase activity was detected, there was no different in activity between control and CF fibroblasts or in the level of phosphatase protein as determined by radioimmunoassay. Lower amounts of /sup 125/I-calmodulin were bound to the 46.5-kD calmodulin-binding protein in CF fibroblasts as compared with controls. The 46.5-kD calmodulin-binding protein may be reduced in CF fibroblasts or its structure may be altered resulting in a reduced binding capacity and/or affinity for calmodulin and perhaps reflecting, either directly or indirectly, the genetic defect responsible for cystic fibrosis.

  4. Collagen chains detected by western blotting using a /sup 125/I-labeled 45K fragment of fibronectin (45K FN)

    SciTech Connect

    Ristagno, R.; Heimer, R.; Fishman, A.P.; Sampson, P.M.

    1987-05-01

    The objective was to improve the sensitivity and specificity of detection of unlabeled collagen chains in biologic fluids. Chains of Types I,II,III,IV and XI (1..cap alpha..2..cap alpha..3..cap alpha..) collagen were separated by SDS PAGE. Their complete transfer to nitrocellulose was obtained by electrophoresis for 16 h at 150 mA with 10 mM Tris, 117 mM glycine, 100 mM cysteine, 0.1% SDS and 10% methanol. The 45K FN was prepared by chymotryptic digestion of fibronectin adsorbed to gelatin-Sepharose, followed by elution with 1.2 M urea, 1 M Tris-NaCl, pH 8.3 and iodination. When exposed to the nitrocellulose transblot at pH 9.5 and 4/sup 0/C, 45K FN did not react with IgG, fibrinogen, myosin, albumin or carbonic anhydrase. These proteins interfere in the assay under conditions of lower pH and higher temperature. The autoradiographs of the transblots were evaluated by densitometry and reflected results also obtained by dot blotting, that chains of collagen Types I,II,III were detectable at 4 ng and those of collagen Type IV at 12 ng. Generally, ..cap alpha..,BETA, and ..gamma.. chains were detectable. The 45K FN reacted equally with ..cap alpha..1(I) and ..cap alpha..2(I), but for Type XI the 1..cap alpha.. chain had considerably more reactivity than 2..cap alpha.. or 3..cap alpha... As the 45K FN was specific for collagens added to plasma, the authors method appears useful for qualitative and quantitative assays of unlabeled collagens in biologic fluids.

  5. Interaction of /sup 125/I-labeled botulinum neurotoxins with nerve terminals. II. Autoradiographic evidence for its uptake into motor nerves by acceptor-mediated endocytosis

    SciTech Connect

    Black, J.D.; Dolly, J.O.

    1986-01-01

    Using pharmacological and autoradiographic techniques it has been shown that botulinum neurotoxin (BoNT) is translocated across the motor nerve terminal membrane to reach a postulated intraterminal target. In the present study, the nature of this uptake process was investigated using electron microscopic autoradiography. It was found that internalization is acceptor-mediated and that binding to specific cell surface acceptors involves the heavier chain of the toxin. In addition, uptake was shown to be energy and temperature-dependent and to be accelerated by nerve stimulation, a treatment which also shortens the time course of the toxin-induced neuroparalysis. These results, together with the observation that silver grains were often associated with endocytic structures within the nerve terminal, suggested that acceptor-mediated endocytosis is responsible for toxin uptake. Possible recycling of BoNT acceptors (an important aspect of acceptor-mediated endocytosis of toxins) at motor nerve terminals was indicated by comparing the extent of labeling in the presence and absence of metabolic inhibitors. On the basis of these collective results, it is concluded that BoNT is internalized by acceptor-mediated endocytosis and, hence, the data support the proposal that this toxin inhibits release of acetylcholine by interaction with an intracellular target.

  6. 75 FR 15726 - Polyvinyl Alcohol From Taiwan; Determination

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-30

    ... COMMISSION Polyvinyl Alcohol From Taiwan; Determination On the basis of the record \\1\\ developed in the... Taiwan of polyvinyl alcohol provided for in subheading 3905.30.00 of the Harmonized Tariff Schedule of... threatened with material injury by reason of allegedly LTFV imports of polyvinyl alcohol from...

  7. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  8. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  9. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  10. 21 CFR 177.1670 - Polyvinyl alcohol film.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polyvinyl alcohol film. 177.1670 Section 177.1670... Components of Single and Repeated Use Food Contact Surfaces § 177.1670 Polyvinyl alcohol film. Polyvinyl alcohol film may be safely used in contact with food of the types identified in § 176.170(c) of...

  11. 76 FR 13982 - Antidumping Duty Order: Polyvinyl Alcohol From Taiwan

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-15

    ... International Trade Administration Antidumping Duty Order: Polyvinyl Alcohol From Taiwan AGENCY: Import... Department is issuing an antidumping duty order on polyvinyl alcohol (PVA) from Taiwan. DATES: Effective Date... value in the antidumping duty investigation of PVA from Taiwan. See Polyvinyl Alcohol From Taiwan:...

  12. Pyrrolidon carboxypeptidase activities in the hypothalamus-pituitary-thyroid and hypothalamus-pituitary-ovary axes of rats with mammary gland cancer induced by N-methyl nitrosourea.

    PubMed

    Carrera, M P; Ramírez-Expósito, M J; Valenzuela, M T; García, M J; Mayas, M D; Arias de Saavedra, J M; Sánchez, R; Pérez, M C; Martínez-Martos, J M

    2005-02-01

    Pyrrolidon carboxypeptidase is an omega-peptidase that hydrolyses N-terminal pyroglutamyl residues from biologically active peptides such as gonadotropin-releasing and thyrotrophin-releasing hormones. We previously described a decrease in both rat and human pyrrolidon carboxypeptidase activity with breast cancer, suggesting that gonadotropin-releasing hormone may be an important local intracrine, autocrine and/or paracrine hormonal factor in the pathogenesis of breast cancer while playing a role in the tumoral process. However, the other susceptible substrate of pyrrolidon carboxypeptidase, thyrotrophin-releasing hormone, may also be modified with breast cancer, supporting an association between breast cancer and thyroid disorders. The present work analyses soluble and membrane-bound pyrrolidon carboxypeptidase activities in the hypothalamus-pituitary-thyroid and hypothalamus-pituitary-ovary axes in N-methyl nitrosourea-induced breast cancer in rats. Our aim was to determine the possible relationship between gonadotropin-releasing hormone and thyrotrophin-releasing hormone regulation through pyrrolidon carboxypeptidase activity. We propose that pyrrolidon carboxypeptidase activity dysregulation at various local and systemic levels may participate in the initiation, promotion and progression of breast cancer induced in rat by N-methyl nitrosourea through the increase in gonadotropin-releasing hormone. Since pyrrolidon carboxypeptidase activity also acts on thyrotrophin-releasing hormone, the dysregulation of this enzyme's activity could indirectly affect hypothalamus-pituitary-thyroid axis function, and thus potentially represent a link between the diseases of thyroid and breast cancer.

  13. Synthesis and dielectric studies of poly (vinyl pyrrolidone) / titanium dioxide nanocomposites

    NASA Astrophysics Data System (ADS)

    Vasudevan, Prathibha; Thomas, Sunil; V, Arunkumar K.; S, Karthika; V, Unnikrishnan N.

    2015-02-01

    In this paper, we present the synthesis of poly vinyl pyrrolidone (PVP) / titanium dioxide nanocomposites via sol- gel technique. The structural and dielectric properties of the samples were also analysed in this work. PVP doped with varying concentrations of TiO2 are prepared by the sol-gel route. The prepared composites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and impedance spectroscopy. XRD and TEM confirm the presence of TiO2 nanoparticles in the composites. The dielectric response and the AC electrical conductivity of the samples are investigated for the frequency range 1 kHz-2MHz at room temperature. The dielectric studies show low values for dielectric constant and loss at high frequencies.

  14. Integrated antifouling and bactericidal polymer membranes through bioinspired polydopamine/poly(N-vinyl pyrrolidone) coating

    NASA Astrophysics Data System (ADS)

    Wang, Xianghong; Yuan, Shuaishuai; Shi, Dean; Yang, Yingkui; Jiang, Tao; Yan, Shunjie; Shi, Hengchong; Luan, Shifang; Yin, Jinghua

    2016-07-01

    Polypropylene (PP) non-woven has been widely used as wound dressing; however, the hydrophobic nature of PP can initiate bacterial attachment and subsequent biofilm formation. Herein, we propose a facile approach to functionalize PP non-woven with poly(ethylene glycol) (PEG) and poly(N-vinyl pyrrolidone)-iodine complex (PVP-I). PVP and PEG were successively tethered onto PP non-woven surface via versatile bioinspired dopamine (DA) chemistry, followed by complexing iodine with PVP moieties. It was demonstrated through the field emission scanning electron microscope (SEM) and spread plate method that the as-modified PP non-woven integrated both antifouling property of PEG for suppressing bacterial adhesion, and bactericidal property of PVP-I for killing the few adherent bacteria. Meanwhile, it could greatly resist platelet and red blood cell adhesion. The integrated antifouling and bactericidal PP non-woven surfaces might have great potential in various wound dressing applications.

  15. Optimization of aceclofenac-loaded pectinate-poly(vinyl pyrrolidone) beads by response surface methodology.

    PubMed

    Nayak, Amit Kumar; Kalia, Samir; Hasnain, M Saquib

    2013-11-01

    The paper describes development of aceclofenac-loaded pectinate-poly(vinyl pyrrolidone) [PVP] beads through ionotropic-gelation. Effects of amount of pectin and PVP on drug encapsulation efficiency (DEE), and cumulative drug release at 6h (R6h) were optimized by using response surface methodology. The optimized beads showed DEE of 96.58 ± 4.15% and R6h of 41.62 ± 2.18% with controlled drug release pattern. FTIR spectroscopy analysis revealed possible intermolecular hydrogen bonding, which could be formed between C=O groups of PVP and -OH groups of pectin in these beads. The swelling of these beads were influenced by pH of the medium.

  16. Biomonitoring of exposure to N-methyl-2-pyrrolidone in workers of the automobile industry.

    PubMed

    Meier, Swetlana; Schindler, Birgit K; Koslitz, Stephan; Koch, Holger M; Weiss, Tobias; Käfferlein, Heiko U; Brüning, Thomas

    2013-07-01

    N-methyl-2-pyrrolidone (NMP) is an important organic solvent for varnishes in industry. NMP has been previously shown to be a developmental toxicant in rodents. This study reports current exposures to NMP in the spraying department of an automobile plant using biological monitoring. Two specific metabolites, 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methyl-succinimide (2-HMSI), were analyzed in 69 urine samples of 14 workers exposed to NMP and 9 nonexposed controls. Three different working tasks ('loading' and 'cleaning' of the sprayer system and 'wiping/packing' of the sprayed materials) and three sampling times (preshift, postshift, and preshift of the following day) were studied in exposed workers. Median exposures of 5-HNMP and 2-HMSI in postshift urine of exposed workers were 0.91 and 0.52mg g(-1) creatinine, respectively, whereas median levels in controls were below the limit of detection. Decreased levels of 5-HNMP were observed in preshift urine samples on the following day (0.39mg g(-1) creatinine) in exposed workers, while the concentration of 2-HMSI did not change (0.49mg g(-1) creatinine). Highest exposures occurred during sprayer cleaning with a maximum level of 8.31mg g(-1) creatinine of 5-HNMP in postshift urine. In contrast to 'wipers/packers', no decrease in 5-HNMP could be observed in preshift urine samples on day 2 of the 'loaders' and 'cleaners'. Overall, exposure in terms of 5-HNMP postshift and 2-HMSI preshift of the following day were well below the current biological limit values of the European Union (70 and 20mg g(-1) creatinine). Our results provide initial data on NMP exposure in the automobile industry and suggest that the analysis of 5-HNMP in preshift samples also provides essential information, particularly in situations involving direct handling of liquid NMP-containing formulations.

  17. Hydrophilization of Polyvinyl Chloride Surface by Ozonation

    NASA Astrophysics Data System (ADS)

    Kurose, Keisuke; Okuda, Tetsuji; Nakai, Satoshi; Tsai, Tsung-Yueh; Nishijima, Wataru; Okada, Mitsumasa

    The surface modification mechanism of polyvinyl chloride (PVC) by ozonation was investigated to study the selective hydrophilization of PVC surface among other plastics. Infrared analysis confirmed the increase of hydrophilic groups. XPS analysis revealed that the increase was due to the structural change in chlorine group in PVC to hydroxylic acid, ketone, and carboxylic groups by ozonation. This chemical reaction by ozone could occur only for polymers with chlorides in its structure and resulted in the selective hydrophilization of PVC among various polymers.

  18. Solubility of pioglitazone hydrochloride in binary mixtures of polyethylene glycol 400 with ethanol, propylene glycol, N-methyl-2-pyrrolidone, and water at 25 degrees C.

    PubMed

    Jouyban, Abolghasem; Soltanpour, Shahla

    2010-09-01

    The solubility of pioglitazone hydrochloride in binary mixtures of polyethylene glycol 400 with ethanol, N-methyl-2-pyrrolidone, propylene glycol, and water at 25 degrees C are reported. The generated data are fitted to the Jouyban-Acree model and the mean relative deviations are 2.6%, 1.5%, 5.8%, and 7.4%, respectively for ethanol, N-methyl-2-pyrrolidone, propylene glycol, and water.

  19. Enhancement of Mycophenolate Mofetil Permeation for Topical Use by Eucalyptol and N-Methyl-2-pyrrolidone

    PubMed Central

    Songkram, Chalermkiat

    2016-01-01

    Mycophenolate mofetil (MMF) is a prodrug of mycophenolic acid (MPA) which can be metabolized by esterase. MMF has been approved by the United States Food and Drug Administration (USFDA) for treatment of psoriasis patient with skin symptoms. However, it remains unclear whether MMF is efficiently effective to treat skin symptoms developed from psoriasis. The insufficient amount of MMF penetrating through the skin results in the treatment failure due to the difficulty in MMF penetration through the stratum corneum. Skin permeation enhancers such as eucalyptol (EUL) and N-methyl-2-pyrrolidone (NMP) potentially aid in increasing skin penetration. This study aimed to investigate the effects of a concentration ratio (% w/v) between two enhancers (EUL and NMP). The results showed that EUL enhanced MMF permeation with an enhancement ratio (ER) of 3.44 while NMP was not able to promote the penetration of MMF. Interestingly, the synergistic effect of the two enhancers was observed with a suitable ratio given that the ER was 8.21. EUL and NMP are promising enhancers for the development of MMF based skin product. PMID:27069715

  20. Calorimetric investigation of polyaniline and 1-methyl 2-pyrrolidone (NMP) mixtures

    NASA Astrophysics Data System (ADS)

    Delmas, Geneviàve

    2001-03-01

    Mixing polyaniline powder (Pani) with polar solvents such as 1-methyl-2-pyrrolidone (NMP) generates a strong interaction at RT as indicated by the immediate development on contact of color and heat. Stirring increases color only if it is vigorous.It does not lead to complete solubility.The question arises of a dispersion or a dissolution of Pani in NMP. It was found that a oxygen-free mixture undergoes a phase-change in a slow T-ramp (0.1K/min) between 72 and 120o C.The values of Δ H are large, exothermic and critically dependant on the mixture history and nominal concentration. As an example, in similar stirring conditions at RT, Δ H increases from -2,000 to -20,000 J/g when c (nominal ) diminishes from 1.3 to 0.3 mg/cm3. Stirring is achieved either with a magnetic stirrer, by sonication or by gentle shaking. The UV-visible spectra of mixtures are measured at RT as a function of stirring conditions and c (nominal).The values of Δ H obtained in different conditions, show that the formation of a dispersion is not a pre-requisite for the phase-change. Reversibility of the phase-change is being investigated.

  1. Adsorption property of Rhodamine 6G onto chitosan-g-(N-vinyl pyrrolidone)/montmorillonite composite.

    PubMed

    Vanamudan, Ageetha; Bandwala, Khusbu; Pamidimukkala, Padmaja

    2014-08-01

    A series of chitosan-g-(N-vinyl pyrrolidone)/montmorillonite hydrogel composites were synthesized by in situ intercalative polymerization. The properties of the composites were investigated by FTIR, XRD, scanning electron microscopy and differential scanning calorimetry. The morphologies of the hydrogel composites were sponge like with a homogeneous structure. The effects of clay on the swelling, morphology, glass transition (Tg), and water structure were studied. The swelling of the hydrogel composites formed was found to be affected by the pH of the medium and the electrolyte. Maximum swelling was observed in the hydrogel containing low percentage of clay (H-0.2) and was used to investigate the adsorption of a water soluble cationic dye Rhodamine 6G (Rh6G). The results show that the adsorption capacity for the dye increased with increase in dose, contact time but there was no change observed with respect to increase in temperature. The adsorption kinetics of Rh6G followed Pseudo second order model and the equilibrium data was found to fit Freundlich model.

  2. Serum pyrrolidone carboxypeptidase activity in N-methyl-nitrosourea induced rat breast cancer.

    PubMed

    Carrera, M P; Ramírez-Expósito, M J; Valenzuela, M T; García, M J; Mayas, M D; Martínez-Martos, J M

    2003-08-01

    Pyrrolidone carboxypeptidase (Pcp) (E.C. 3.4.19.3) is an omega peptidase widely distributed in animal fluids and tissues and hydrolyses N-terminal pyroglutamic residues from biologically active peptides such as gonadotropin releasing hormone (GnRH). Previous results obtained by us showed a decrease in human breast cancer Pcp activity, suggesting that this enzyme activity or its putative substrates may play a major role in breast cancer pathogenesis. The aim of the present work is to analyse serum Pcp activity in N-methyl-nitrosourea (NMU) induced rat mammary tumours using pyroglutamyl-beta-naphthylamide as substrate. Serum Pcp activity was significantly lower in NMU-treated rats than in controls. Moreover, multiple regression analysis showed a significant correlation between Pcp activity and the number and size of tumours and the body weight of the animals. Since NMU-induced carcinomas are mainly oestrogen-dependent, the decrease observed in Pcp activity may reflect an increase in circulating levels of GnRH that lead to an increase in gonadal steroid hormones production responsible, at least in part, for the initiation and promotion of the disease.

  3. Poly(N-vinyl-2-pyrrolidone) and 1-Octyl-2-pyrrolidinone Modified Ionic Microemulsions.

    PubMed

    Beitz, T.; Kötz, J.; Wolf, G.; Kleinpeter, E.; Friberg, S. E.

    2001-08-15

    The influence of the nonionic polymer poly(N-vinyl-2-pyrrolidone) (PVP) in comparison to the surfactant 1-octyl-2-pyrrolidinone (OP) on the phase behavior of the system SDS/pentanol/xylene/water was studied. In both modified systems a strong increase in the water solubilization capacity was found, accompanied by a change in the spontaneous curvature toward zero. In the polymer-modified system an isotropic phase channel is formed with increasing polymer content that connects the L1 and the L2 phase. The lamellar liquid crystalline phase is destabilized in both cases. In the L1 phase the adsorption of PVP at the surface of the microemulsion droplets and the formation of a cluster-like structure is proven by several methods like (13)C NMR T(1) relaxation time measurments, zeta potential measurements, and rheology. In the L2 phase a modification of the interface of the inverse droplets is detected by a shift in the percolation boundary (conductivity) and (13)C NMR T(1) relaxation measurements. The formation of a cluster-like structure can be assumed on the basis of our rheological measurements. Copyright 2001 Academic Press.

  4. Blend miscibility of cellulose propionate with poly(N-vinyl pyrrolidone-co-methyl methacrylate).

    PubMed

    Sugimura, Kazuki; Teramoto, Yoshikuni; Nishio, Yoshiyuki

    2013-10-15

    The blend miscibility of cellulose propionate (CP) with poly(N-vinyl pyrrolidone-co-methyl methacrylate) (P(VP-co-MMA)) was investigated. The degree of substitution (DS) of CP used ranged from 1.6 to >2.9, and samples for the vinyl polymer component were prepared in a full range of VP:MMA compositions. Through DSC analysis and solid-state (13)C NMR and FT-IR measurements, we revealed that CPs of DS<2.7 were miscible with P(VP-co-MMA)s of VP≥~10mol% on a scale within a few nanometers, in virtue of hydrogen-bonding interactions between CP-hydroxyls and VP-carbonyls. When the DS of CP exceeded 2.7, the miscibility was restricted to the polymer pairs using P(VP-co-MMA)s of VP=ca. 10-40 mol%; the scale of mixing in the blends concerned was somewhat larger (ca. 5-20 nm), however. The appearance of such a "miscibility window" was interpretable as an effect of intramolecular repulsion in the copolymer component. Results of DMA and birefringence measurements indicated that the miscible blending of CP with the vinyl polymer invited synergistic improvements in thermomechanical and optical properties of the respective constituent polymers. Additionally, it was found that the VP:MMA composition range corresponding to the miscibility window was expanded by modification of the CP component into cellulose acetate propionate.

  5. Adsorption of α-amylase onto poly(N-vinyl 2-pyrrolidone/itaconic acid) hydrogels

    NASA Astrophysics Data System (ADS)

    Tümtürk, Hayrettin; Çaykara, Tuncer; Kantoǧlu, Ömer; Güven, Olgun

    1999-05-01

    α-Amylase enzyme was adsorbed on poly(N-vinyl 2-pyrrolidone/itaconic acid) (P(VP/IA)) hydrogels prepared by irradiating the ternary mixtures of VP/IA/water by γ-rays at ambient temperature. The adsorption capacity of the hydrogels was determined to increase from 2.30 to 3.40 mg α-amylase/g dry gel with increasing amount of IA in gel system. Kinetic parameters were calculated as 2.51 g/dm 3 for Km and 1.67 × 10 -3 g/dm 3 min for Vmax for free enzyme and in the range of 3.88-5.02 g/dm 3 for Km and 1.62 × 10 -3-2.27 × 10 -3 g/dm 3 min for Vmax depending on the amount of IA in the hydrogel. Enzyme activities were found to increase from 49.9% to 77.4% with increasing amount of IA in the gel system and retained their activities for one month storage. On the other hand, the free enzyme loses its activity completely after 20 days.

  6. Polyvinyl alcohol as photoluminescent conductive polymer

    NASA Astrophysics Data System (ADS)

    Ruiz-Limón, B.; Wetzel, G. B. J.; Olivares-Pérez, A.; Ponce-Lee, E. L.; Hernández-Garay, M. P.; Páez-Trujillo, G.; Toxqui-López, S.; Fuentes-Tapia, I.

    2007-02-01

    We synthesized a photoluminescent conductor polymer composed of polyvinyl alcohol, which was doped with nickel chloride to decrease its resistivity (300 Ωcm) and benzalkonium chloride to obtain photoluminescence properties, when it is radiated with a green laser beam (532 nm). We compared its absorbance curve and its energy emitted curve to observe the amount energy that is taken advantage of this process. Besides we research the photoluminescence behavior when an electric currant is applied in our conductor polymer, obtaining a modulation capacity.

  7. Complex compound polyvinyl alcohol-titanic acid/titanium dioxide

    NASA Astrophysics Data System (ADS)

    Prosanov, I. Yu.

    2013-02-01

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

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

    EPA Science Inventory

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

  9. Insights into the coal extractive solvent N-methyl-2-pyrrolidone + carbon disulfide

    SciTech Connect

    Santiago Aparicio; Mara J. Davila; Rafael Alcalde

    2009-03-15

    A wide set of experimental and computational tools were used to characterize the N-methyl-2-pyrrolidone (NMP) + carbon disulfide mixed solvent in the full composition range. The interest in this solvent rose from its very efficient use for coal extraction through a mechanism still not fully understood. Thermophysical properties at ambient pressure together with pressure-volume-temperature (PVT) behavior were measured with the objective of providing the required data for the industrial use of the mixed fluid and to get insight into the fluid structure at the molecular level. NMR, FTIR, and solvatochromic studies were performed together with microwave dielectric relaxation spectroscopy (DRS) measurements, thus providing more information on the fluid's structure and allowing one to relate the molecular level behavior with the measured macroscopic properties. Moreover, density functional theory (DFT) and classical molecular dynamics simulations (MD) were used to obtain a detailed picture of the intermolecular interactions within the fluid, at short and long ranges, and of other relevant features leading to the structure of the studied system. The whole study leads to a fluid's picture in which carbon disulfide hinders the development of NMP/NMP intermolecular dipolar interactions, thus increasing the monomer population. We should remark that some properties reported in this work are in remarkable disagreement with previously reported studies, the most important one being the positive excess molar volume in the whole pressure-temperature range studied, which contrasts with the negative values reported in the literature. Previously reported properties are hardly justified with a coherent molecular level picture, whereas the whole collection of properties reported in this work leads to a more reasonable fluid's structure. 56 refs., 17 figs., 2 tabs.

  10. Poly(vinyl chloride) processes and products.

    PubMed Central

    Wheeler, R N

    1981-01-01

    Poly(vinyl chloride) resins are produced by four basic processes: suspension, emulsion, bulk and solution polymerization. PVC suspensions resins are usually relatively dust-free and granular with varying degrees of particle porosity. PVC emulsion resins are small particle powders containing very little free monomer. Bulk PVC resins are similar to suspension PVC resins, though the particles tend to be more porous. Solution PVC resins are smaller in particle size than suspension PVC with high porosity particles containing essentially no free monomer. The variety of PVC resin products does not lend itself to broad generalizations concerning health hazards. In studying occupational hazards the particular PVC process and the product must be considered and identified in the study. PMID:7333230

  11. [Survey of plasticizers in polyvinyl chloride toys].

    PubMed

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

    2012-01-01

    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.

  12. Dynamical Properties of Plasticizer in Polyvinyl Acetate

    NASA Astrophysics Data System (ADS)

    Gautam, S.; Alvarez, F.; Arbe, A.; Tyagi, M.; Frick, B.; Colmenero, J.

    2011-07-01

    Dynamical properties of polymers in a blend are known to exhibit unusual features. For example, dynamic heterogeneities can be observed in a blend with asymmetries in the composition or the glass transition temperature of the blend components. The relaxation functions corresponding to the individual components in such a blend are also known to be broadened. If the asymmetry is large, even confinement like features can be observed. A similar situation could arise in an asymmetric system consisting of a polymer and a low molecular weight system (a plasticizer). Here we report the structural and dynamical properties of a system with 75% PVAc/25%trimer (Polyvinyl acetate and its trimer), a system with high Tg asymmetry (Tg(PVAc) = 314 K, Tg (Trimer) = 209 K, Tg(Average) = 259 K).

  13. Thermal Decomposition and Stabilisation of Poly(vinyl Chloride)

    NASA Astrophysics Data System (ADS)

    Troitskii, B. B.; Troitskaya, L. S.

    1985-08-01

    The kinetics and mechanism of the thermal dehydrochlorination of poly(vinyl chloride) and low-molecular-weight chlorohydrocarbons which model various fragments of the polymer molecule, are discussed. Studies designed to determine the qualitative and quantitative compositions of the unstable fragments in poly(vinyl chloride) macromolecules by 13C NMR are examined. Attention is concentrated on the consideration of the mechanism of the action of the most effective thermostabilisers for the polymer - organotin compounds. The principal features of synergism in the stabilisation of poly(vinyl chloride) and the mechanism of the action of synergistic mixtures are analysed. The bibliography includes 107 references.

  14. Removal of some textile dyes from aqueous solutions by poly( N-vinyl-2-pyrrolidone) and poly( N-vinyl-2-pyrrolidone)/K 2S 2O 8 hydrogels

    NASA Astrophysics Data System (ADS)

    Can, Hatice Kaplan; Kirci, Betül; Kavlak, Serap; Güner, Ali

    2003-12-01

    Poly( N-vinyl-2-pyrrolidone)/water and poly( N-vinyl-2-pyrrolidone)/K 2S 2O 8/water systems are hydrogels prepared by irradiation with γ-rays at ambient temperature. Both hydrogel systems were employed for diffusion and swelling experiments in various textile dyes aqueous solutions (textile dyes such as Cibacron Blue (CB) F3GA, Methyl Orange (MO), Congo Red (CR)). For these hydrogel systems, swelling studies indicated that swelling percentages increased in the following order: MO>CB F3GA>CR at fixed dose 96 kGy. Because of this reason MO dye solution has been chosen and all swelling properties are investigated for 26, 64, 96 and 124 kGy. The swelling capabilities of PVP and PVP/K 2S 2O 8 hydrogels in MO dye solution vary in the range of 400-1500%. The diffusion of dye solutions PVP and PVP/K 2S 2O 8 hydrogels was assumed to be Fickian character. The swelling behavior of PVP and PVP/K 2S 2O 8 hydrogels exhibits second-order kinetic in all dye solutions. Diffusion coefficient, initial swelling rate, swelling rate constant, maximum swelling and equilibrium water/dye content were found for all gel systems in dye solutions.

  15. Polyvinyl alcohol cross-linked with two aldehydes

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  16. In Situ Cross-Linking of Polyvinyl Alcohol Films

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    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.

  17. Human volunteer study on the inhalational and dermal absorption of N-methyl-2-pyrrolidone (NMP) from the vapour phase.

    PubMed

    Bader, Michael; Wrbitzky, Renate; Blaszkewicz, Meinolf; Schäper, Michael; van Thriel, Christoph

    2008-01-01

    N-Methyl-2-pyrrolidone (NMP) is a versatile organic solvent frequently used for surface cleaning such as paint stripping or graffiti removal. Liquid NMP is rapidly absorbed through the skin but dermal vapour phase absorption might also play an important role for the uptake of the solvent. This particular aspect was investigated in an experimental study with 16 volunteers exposed to 80 mg/m(3) NMP for 8 h under either whole-body, i.e. inhalational plus dermal, or dermal-only conditions. Additionally, the influence of moderate physical workload on the uptake of NMP was studied. The urinary concentrations of NMP and its metabolites 5-hydroxy-N-methyl-2-pyrrolidone (5-HNMP) and 2-hydroxy-N-methylsuccinimide (2-HMSI) were followed for 48 h and analysed by gas chromatography-mass spectrometry (GC-MS). Percutaneous uptake delayed the elimination peak times and the apparent biological half-lives of NMP and 5-HNMP. Under resting conditions, dermal-only exposure resulted in the elimination of 71 +/- 8 mg NMP equivalents as compared to 169 +/- 15 mg for whole-body exposure. Moderate workload yielded 79 +/- 8 mg NMP (dermal-only) and 238 +/- 18 mg (whole-body). Thus, dermal absorption from the vapour phase may contribute significantly to the total uptake of NMP, e.g. from workplace atmospheres. As the concentration of airborne NMP does not reflect the body dose, biomonitoring should be carried out for surveillance purposes.

  18. X-ray crystalline structures of pyrrolidone carboxyl peptidase from a hyperthermophile, Pyrococcus furiosus, and its cys-free mutant.

    PubMed

    Tanaka, H; Chinami, M; Mizushima, T; Ogasahara, K; Ota, M; Tsukihara, T; Yutani, K

    2001-07-01

    In order to elucidate the mechanism of the thermostability of proteins from hyperthermophiles, X-ray crystalline structures of pyrrolidone carboxyl peptidase from a hyperthermophile, Pyrococcus furiosus (PfPCP), and its mutant protein with Ser substituted at Cys142 and Cys188 were determined at 2.2 and 2.7 A resolution, respectively. The obtained structures were compared with those previously reported for pyrrolidone carboxyl peptidases from a hyperthermophilie, Thermococcus litoralis (TlPCP), and from a mesophile, Bacillus amyloliquefaciens (BaPCP). The PfPCP structure is a tetramer of four identical subunits similar to that of the TlPCP and BaPCP. The largest structural changes among the three PCPs were detected in the C-terminal protrusion, which interacts with that of another subunit. A comparison of the three structures indicated that the high stability of PfPCP is caused by increases in hydrophobic interactions and hydrogen bonds, the formation of an intersubunit ion-pair network, and improvement to an ideal conformation. On the basis of the structures of the three proteins, it can be concluded that PfPCP does not have any special factors responsible for its extremely high stability and that the conformational structure of PfPCP is superior in its combination of positive and negative stabilizing factors compared with BaPCP.

  19. Piezoresistive Properties of Polyvinyl Chloride Composites

    NASA Astrophysics Data System (ADS)

    Toprakci, Hatice Aylin Karahan

    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.

  20. Ultrasonic depolymerization of aqueous polyvinyl alcohol.

    PubMed

    Grönroos, A; Pirkonen, P; Heikkinen, J; Ihalainen, J; Mursunen, H; Sekki, H

    2001-07-01

    Ultrasonication has proved to be a highly advantageous method for depolymerizing macromolecules because it reduces their molecular weight simply by splitting the most susceptible chemical bond without causing any changes in the chemical nature of the polymer. Most of the effects involved in controlling molecular weight can be attributed to the large shear gradients and shock waves generated around collapsing cavitation bubbles. In general, for any polymer degradation process to become acceptable to industry, it is necessary to be able to specify the sonication conditions which lead to a particular relative molar mass distribution. This necessitates the identification of the appropriate irradiation power, temperature, concentration and irradiation time. According to the results of this study the reactors constructed worked well in depolymerization and it was possible to degrade aqueous polyvinyl alcohol (PVA) polymer with ultrasound. The most extensive degradation took place at the lowest frequency used in this study, i.e. 23 kHz, when the input power was above the cavitation threshold and at the lowest test concentration of PVA, i.e. 1% (w/w). Thus this study confirms the general assumption that the shear forces generated by the rapid motion of the solvent following cavitational collapse are responsible for the breakage of the chemical bonds within the polymer. The effect of polymer concentration can be interpreted in terms of the increase in viscosity with concentration, causing the molecules to become less mobile in solution and the velocity gradients around the collapsing bubbles to therefore become smaller.

  1. Preparation and properties of polyvinyl alcohol microspheres

    SciTech Connect

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

    1986-06-01

    Polyvinyl alcohol (PVA) microspheres, having a size range of approx.150- to 250-..mu..m diameter with 1- to 5-..mu..m wall thickness, have been fabricated using a solution droplet technique. The spheres were developed for possible use on the Lawrence Livermore National Laboratory (LLNL) Inertial Confinement Fusion (ICF) Program. PVA, a polymer chosen based on earlier survey work carried out at KMS Fusion, Inc., has good strength, low hydrogen permeability, is optically transparent, and water soluble. The latter property makes it safe and easy to use in our droplet generator system. A unique dual-orifice droplet generator was used to prepare the spheres. The droplet generator operating conditions and the column processing parameters were chosen using results from our 1-D model calculations as a guide. The polymer microsphere model is an extension of the model we developed to support the glass sphere production. After preparation, the spheres were physically characterized for surface quality, sphericity, wall thickness (and uniformity), and size. We also determined the buckling pressure for both uncoated and CH-coated spheres. Radiation stability to beta decay (from tritium) was evaluated by exposing the spheres to a 7-keV electron beam. The results from these and other physical property measurements are presented in this report.

  2. Hydrothermal carbonization of poly(vinyl chloride).

    PubMed

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

    2015-01-01

    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 μg g(-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.

  3. Polyvinyl polypyrrolidone attenuates genotoxicity of silver nanoparticles synthesized via green route, tested in Lathyrus sativus L. root bioassay.

    PubMed

    Panda, Kamal K; Achary, V Mohan M; Phaomie, Ganngam; Sahu, Hrushi K; Parinandi, Narasimham L; Panda, Brahma B

    2016-08-01

    The silver nanoparticles (AgNPs) were synthesized extracellularly from silver nitrate (AgNO3) using kernel extract from ripe mango Mengifera indica L. under four different reaction conditions of the synthesis media such as the (i) absence of the reducing agent, trisodium citrate (AgNPI), (ii) presence of the reducing agent (AgNPII), (iii) presence of the cleansing agent, polyvinyl polypyrrolidone, PVPP (AgNPIII), and (iv) presence of the capping agent, polyvinyl pyrrolidone, PVP (AgNPIV). The synthesis of the AgNPs was monitored by UV-vis spectrophotometry. The AgNPs were characterised by the energy-dispersive X-ray spectroscopy, transmission electron microscopy, X-ray diffraction, and small-angle X-ray scattering. Functional groups on the AgNPs were established by the Fourier transform infrared spectroscopy. The AgNPs (AgNPI, AgNPII, AgNPIII and AgNPIV) were spherical in shape with the diameters and size distribution-widths of 14.0±5.4, 19.2±6.6, 18.8±6.6 and 44.6±13.2nm, respectively. Genotoxicity of the AgNPs at concentrations ranging from 1 to 100mgL(-1) was determined by the Lathyrus sativus L. root bioassay and several endpoint assays including the generation of reactive oxygen species and cell death, lipid peroxidation, mitotic index, chromosome aberrations (CA), micronucleus formation (MN), and DNA damage as determined by the Comet assay. The dose-dependent induction of genotoxicity of the silver ion (Ag(+)) and AgNPs was in the order Ag(+)>AgNPII>AgNPI>AgNPIV>AgNPIII that corresponded with their relative potencies of induction of DNA damage and oxidative stress. Furthermore, the findings underscored the CA and MN endpoint-based genotoxicity assay which demonstrated the genotoxicity of AgNPs at concentrations (≤10mgL(-1)) lower than that (≥10mgL(-1)) tested in the Comet assay. This study demonstrated the protective action of PVPP against the genotoxicity of AgNPIII which was independent of the size of the AgNPs in the L. sativus L. root bioassay

  4. Microbial degradation of N-methyl-2-pyrrolidone in surface water and bacteria responsible for the process.

    PubMed

    Růžička, Jan; Fusková, Jana; Křížek, Karel; Měrková, Markéta; Černotová, Alena; Smělík, Michal

    2016-01-01

    Due to widespread utilization in many industrial spheres and agrochemicals, N-methyl-2-pyrrolidone (NMP) is a potential contaminant of different surface water ecosystems. Hence, investigation was made into its aerobic microbial degradability in samples of water from a river, wetland area and spring. The results showed that the compound was degradable in all water types, and that the fastest NMP removal occurred in 4 days in river water, while in the wetland and spring samples the process was relatively slow, requiring several months to complete. Key bacterial degraders were successfully isolated in all cases, and their identification proved that pseudomonads played a major role in NMP degradation in river water, while the genera Rhodococcus and Patulibacter fulfilled a similar task in the wetland sample. Regarding spring water, degrading members of the Mesorhizobium and Rhizobium genera were found.

  5. Solvothermal synthesis of uniform bismuth nanospheres using poly(N-vinyl-2-pyrrolidone) as a reducing agent

    PubMed Central

    2011-01-01

    Uniform bismuth nanospheres were successfully prepared from bismuth nitrate in the presence of poly(N-vinyl-2-pyrrolidone) (PVP) by solvothermal process. The product was characterized by powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction, and energy-dispersive X-ray. PVP plays a critical role both as a reducing agent and a capping agent in the formation of bismuth nanospheres. Shape and size of bismuth nanospheres could be tuned by changing the employed PVP/bismuth salt ratio. It was also found the solvent had an effect on the morphologies of bismuth nanomaterials. The possible formation and growth mechanism of bismuth nanospheres were also discussed and proposed to explain the reduction step. PMID:21711606

  6. Radiation-chemical preparation of poly(vinyl alcohol) hydrogels

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  7. Polyvinyl alcohol battery separator containing inert filler. [alkaline batteries

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  8. 75 FR 38079 - Postponement of Preliminary Determination of Antidumping Duty Investigation: Polyvinyl Alcohol...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ...: Polyvinyl Alcohol From Taiwan AGENCY: Import Administration, International Trade Administration, Department...) initiated the antidumping duty investigation on polyvinyl alcohol from Taiwan. See Initiation of Anti-Dumping Duty Investigation: Polyvinyl Alcohol From Taiwan, 69 FR 59204 (October 4, 2004). On October...

  9. 78 FR 39256 - Polyvinyl Alcohol From Taiwan: Rescission of Antidumping Duty Administrative Review; 2012-2013

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-01

    ...] Polyvinyl Alcohol From Taiwan: Rescission of Antidumping Duty Administrative Review; 2012-2013 AGENCY... on polyvinyl alcohol (PVA) from Taiwan for the period March 1, 2012, through February 28, 2013. DATES... administrative review.\\3\\ \\3\\ See letter from CCPC to the Department, ``Polyvinyl Alcohol from Taiwan:...

  10. [Pulmonary manifestations of polyvinyl chloride exposure].

    PubMed

    Süyür, Hüseyin; Bayram, Nazan; Aydın, Neriman; Uyar, Meral; Gündoğdu, Nevhiz; Elbek, Osman

    2011-01-01

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

  11. Using polyvinyl chloride dyed with bromocresol purple in radiation dosimetry.

    PubMed

    Kattan, Munzer; al Kassiri, Haroun; Daher, Yarob

    2011-02-01

    Polyvinyl chloride (PVC) dyed with bromocresol purple was investigated as a high-dose radiation dosimeter. The absorbance at 417 nm depends linearly on the dose below 50 kGy. The response depends neither on dose rate nor on the irradiation temperature. The effects of post-irradiation storage in the dark and in indirect sunlight are also discussed.

  12. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b)...

  13. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b)...

  14. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b)...

  15. 21 CFR 175.270 - Poly(vinyl fluoride) resins.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... polymerization of vinyl fluoride. (b) The poly(vinyl fluoride) basic resins have an intrinsic viscosity of not... Dilute Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference. Copies may be... Solution Viscosity of Vinyl Chloride Polymers,” which is incorporated by reference; see paragraph (b)...

  16. Embryotoxic potential of N-methyl-pyrrolidone (NMP) and three of its metabolites using the rat whole embryo culture system

    SciTech Connect

    Flick, Burkhard Talsness, Chris E.; Jaeckh, Rudolf; Buesen, Roland; Klug, Stephan

    2009-06-01

    N-methyl-2-pyrrolidone (NMP), which undergoes extensive biotransformation, has been shown in vivo to cause developmental toxicity and, especially after oral treatment, malformations in rats and rabbits. Data are lacking as to whether the original compound or one of its main metabolites is responsible for the toxic effects observed. Therefore, the relative embryotoxicity of the parent compound and its metabolites was evaluated using rat whole embryo culture (WEC) and the balb/c 3T3 cytotoxicity test. The resulting data were evaluated using two strategies; namely, one based on using all endpoints determined in the WEC and the other including endpoints from both the WEC and the cytotoxicity test. On basis of the first analysis, the substance with the highest embryotoxic potential is NMP, followed by 5-hydroxy-N-methyl-pyrrolidone (5-HNMP), 2-hydroxy-N-methylsuccinimide (2-HMSI) and N-methylsuccinimide (MSI). Specific dysmorphogeneses induced by NMP and 5-HNMP were aberrations in the head region of the embryos, abnormal development of the second visceral arches and open neural pores. The second evaluation strategy used only two endpoints of the WEC, i.e. the no observed adverse effect concentration (NOAEC{sub WEC}) and the lowest concentration leading to dysmorphogenesis in 100% of the cultured embryos (IC{sub MaxWEC}). In addition to these WEC endpoints the IC{sub 503T3} from the cytotoxicity test (balb/c 3T3 fibroblasts) was included in the evaluation scheme. These three endpoints were applied to a prediction model developed during a validation study of the European Centre for the Validation of Alternative Methods (ECVAM) allowing the classification of the embryotoxic potential of each compound into three classes (non-, weakly- and strongly embryotoxic). Consistent results from both evaluation strategies were observed, whereby NMP and its metabolites revealed a direct embryotoxic potential. Hereby, only NMP and 5-HNMP induced specific embryotoxic effects and were

  17. Embryotoxic potential of N-methyl-pyrrolidone (NMP) and three of its metabolites using the rat whole embryo culture system.

    PubMed

    Flick, Burkhard; Talsness, Chris E; Jäckh, Rudolf; Buesen, Roland; Klug, Stephan

    2009-06-01

    N-methyl-2-pyrrolidone (NMP), which undergoes extensive biotransformation, has been shown in vivo to cause developmental toxicity and, especially after oral treatment, malformations in rats and rabbits. Data are lacking as to whether the original compound or one of its main metabolites is responsible for the toxic effects observed. Therefore, the relative embryotoxicity of the parent compound and its metabolites was evaluated using rat whole embryo culture (WEC) and the balb/c 3T3 cytotoxicity test. The resulting data were evaluated using two strategies; namely, one based on using all endpoints determined in the WEC and the other including endpoints from both the WEC and the cytotoxicity test. On basis of the first analysis, the substance with the highest embryotoxic potential is NMP, followed by 5-hydroxy-N-methyl-pyrrolidone (5-HNMP), 2-hydroxy-N-methylsuccinimide (2-HMSI) and N-methylsuccinimide (MSI). Specific dysmorphogeneses induced by NMP and 5-HNMP were aberrations in the head region of the embryos, abnormal development of the second visceral arches and open neural pores. The second evaluation strategy used only two endpoints of the WEC, i.e. the no observed adverse effect concentration (NOAEC(WEC)) and the lowest concentration leading to dysmorphogenesis in 100% of the cultured embryos (IC(Max WEC)). In addition to these WEC endpoints the IC(50 3T3) from the cytotoxicity test (balb/c 3T3 fibroblasts) was included in the evaluation scheme. These three endpoints were applied to a prediction model developed during a validation study of the European Centre for the Validation of Alternative Methods (ECVAM) allowing the classification of the embryotoxic potential of each compound into three classes (non-, weakly- and strongly embryotoxic). Consistent results from both evaluation strategies were observed, whereby NMP and its metabolites revealed a direct embryotoxic potential. Hereby, only NMP and 5-HNMP induced specific embryotoxic effects and were classified as

  18. Interaction of 125I-labeled botulinum neurotoxins with nerve terminals. I. Ultrastructural autoradiographic localization and quantitation of distinct membrane acceptors for types A and B on motor nerves

    PubMed Central

    1986-01-01

    The labeling patterns produced by radioiodinated botulinum neurotoxin (125I-BoNT) types A and B at the vertebrate neuromuscular junction were investigated using electron microscopic autoradiography. The data obtained allow the following conclusions to be made. 125I-BoNT type A, applied in vivo or in vitro to mouse diaphragm or frog cutaneous pectoris muscle, interacts saturably with the motor nerve terminal only; silver grains occur on the plasma membrane, within the synaptic bouton, and in the axoplasm of the nerve trunk, suggesting internalization and retrograde intra-axonal transport of toxin or fragments thereof. 125I-BoNT type B, applied in vitro to the murine neuromuscular junction, interacts likewise with the motor nerve terminal except that a lower proportion of internalized radioactivity is seen. This result is reconcilable with the similar, but not identical, pharmacological action of these toxin types. The saturability of labeling in each case suggested the involvement of acceptors; on preventing the internalization step with metabolic inhibitors, their precise location became apparent. They were found on all unmyelinated areas of the nerve terminal membrane, including the preterminal axon and the synaptic bouton. Although 125I-BoNT type A interacts specifically with developing terminals of newborn rats, the unmyelinated plasma membrane of the nerve trunk is not labeled, indicating that the acceptors are unique components restricted to the nerve terminal area. BoNT types A and B have distinct acceptors on the terminal membrane. Having optimized the conditions for saturation of these binding sites and calibrated the autoradiographic procedure, we found the densities of the acceptors for types A and B to be approximately 150 and 630/micron 2 of membrane, respectively. It is proposed that these membrane acceptors target BoNT to the nerve terminal and mediate its delivery to an intracellular site, thus contributing to the toxin's selective inhibitory action on neurotransmitter release. PMID:3733877

  19. Interaction of /sup 125/I-labeled botulinum neurotoxins with nerve terminals. I. Ultrastructural autoradiographic localization and quantitation of distinct membrane acceptors for types A and B on motor nerves

    SciTech Connect

    Black, J.D.; Dolly, J.O.

    1986-01-01

    The labeling patterns produced by radioiodinated botulinum neurotoxin (/sup 125/I-BoNT) types A and B at the vertebrate neuromuscular junction were investigated using electron microscopic autoradiography. The data obtained allow the following conclusions to be made. (a) /sup 125/I-BoNT type A, applied in vivo or in vitro to mouse diaphragm or frog cutaneous pectoris muscle, interacts saturably with the motor nerve terminal only; silver grains occur on the plasma membrane, within the synaptic bouton, and in the axoplasm of the nerve trunk, suggesting internalization and retrograde intra-axonal transport of toxin or fragments thereof. (b) /sup 125/I-BoNT type B, applied in vitro to the murine neuromuscular junction, interacts likewise with the motor nerve terminal except that a lower proportion of internalized radioactivity is seen. This result is reconcilable with the similar, but not identical, pharmacological action of these toxin types. (c) The saturability of labeling in each case suggested the involvement of acceptors; on preventing the internalization step with metabolic inhibitors, their precise location became apparent. They were found on all unmyelinated areas of the nerve terminal membrane, including the preterminal axon and the synaptic bouton. (d) It is not proposed that these membrane acceptors target BoNT to the nerve terminal and mediate its delivery to an intracellular site, thus contributing to the toxin's selective inhibitory action on neurotransmitter release.

  20. 2-Pyrrolidone synthesis from γ-aminobutyric acid produced by Lactobacillus brevis under solid-state fermentation utilizing toxic deoiled cottonseed cake.

    PubMed

    Grewal, Jasneet; Khare, S K

    2017-01-01

    There is an increasing demand of γ-aminobutyric acid (GABA) as drug and food additive, as well as feedstock to produce 2-pyrrolidone, a precursor for the synthesis of nylon 4. 2-Pyrrolidone is a petrochemical and depleting reserve which raises concern for its bio-based production. The study herein describes bio-based economical GABA production from Lactobacillus brevis by solid-state fermentation (SSF) using toxic deoiled cottonseed cake (CSC) as substrate. In general, the use of cottonseed cake remains restricted due to the presence of toxic gossypols. Thus, simultaneous detoxification observed during fermentation also widens the scope of utilization of this residual seedcake for feed use vis-a-vis production of other value added chemicals. The SSF conditions were optimized for maximum GABA production, viz., 19.7 mg/g, CSC of GABA was obtained at 6th day of fermentation with 70 % degradation of gossypols simultaneously. The potential of this bio-based GABA as a platform chemical is demonstrated in the synthesis of 2-pyrrolidone. Thus, a simple and cost-effective strategy for utilizing toxic biomass has been developed as an alternate to chemical synthetic route.

  1. Sol–gel auto combustion synthesis of CoFe{sub 2}O{sub 4}/1-methyl-2-pyrrolidone nanocomposite with ethylene glycol: Its magnetic characterization

    SciTech Connect

    Topkaya, R.; Kurtan, U.; Junejo, Y.; Baykal, A.

    2013-09-01

    Graphical abstract: - Highlights: • CoFe{sub 2}O{sub 4} was generated by sol–gel autocombustion using 1-methyl-2-pyrrolidone and ethylene glycol. • The presence of spin-disordered surface layer on magnetic core was established. • A linear dependence of the coercivity on temperature was fitted to Kneller's law. - Abstract: Magnetic nanoparticles were generated by sol–gel auto combustion synthesis of metal salts in the presence of 1-methyl-2-pyrrolidone, a functional solvent and ethylene glycol as usual solvent. The average crystallite size was obtained by using line profile fitting as 11 ± 5 nm. The saturation magnetization value decreases with usage of the ethylene glycol in synthesis. The observed exchange bias effect further confirms the existence of the magnetically ordered core surrounded by spin-disordered surface layer and the ethylene glycol. Square-root temperature dependence of coercivity can be fitted to Kneller's law in the temperature range of 10–400 K. The reduced remanent magnetization values lower than the theoretical value of 0.5 for non-interacting single domain particles indicate the CoFe{sub 2}O{sub 4}-1-methyl-2-pyrrolidone nanocomposite to have uniaxial anisotropy instead of the expected cubic anisotropy according to the Stoner–Wohlfarth model.

  2. Ibogan, tacaman, and cytotoxic bisindole alkaloids from tabernaemontana. Cononusine, an iboga alkaloid with unusual incorporation of a pyrrolidone moiety.

    PubMed

    Lim, Kuan-Hon; Raja, Vijay J; Bradshaw, Tracey D; Lim, Siew-Huah; Low, Yun-Yee; Kam, Toh-Seok

    2015-05-22

    Six new indole alkaloids, viz., cononusine (1, a rare example of an iboga-pyrrolidone conjugate), ervaluteine (2), vincamajicine (3), tacamonidine (4), 6-oxoibogaine (5), and N(4)-chloromethylnorfluorocurarine chloride (6), and two new vobasinyl-iboga bisindole alkaloids, ervatensines A (7) and B (8), in addition to other known alkaloids, were isolated from the stem-bark extract of the Malayan Tabernaemontana corymbosa. The structures of these alkaloids were established on the basis of NMR and MS analyses and, in one instance (7), confirmed by X-ray diffraction analysis. Vincamajicine (3) showed appreciable activity in reversing multidrug resistance in vincristine-resistant KB cells (IC50 2.62 μM), while ervatensines A (7) and B (8) and two other known bisindoles displayed pronounced in vitro growth inhibitory activity against human KB cells (IC50 < 2 μM). Compounds 7 and 8 also showed good growth inhibitory activity against A549, MCF-7, MDA-468, HCT-116, and HT-29 cells (IC50 0.70-4.19 μM). Cell cycle and annexin V-FITC apoptosis assays indicated that compounds 7 and 8 inhibited proliferation of HCT-116 and MDA-468 cells, evoking apoptotic and necrotic cell death.

  3. Effectiveness of 5-Pyrrolidone-2-carboxylic Acid and Copper Sulfate Pentahydrate Association against Drug Resistant Staphylococcus Strains.

    PubMed

    Governa, Paolo; Miraldi, Elisabetta; De Fina, Gianna; Biagi, Marco

    2016-04-01

    Bacterial resistance is an ongoing challenge for pharmacotherapy and pharmaceutical chemistry. Staphylococcus aureus is the bacterial species which makes it most difficult to treat skin and soft tissue infections and it is seen in thousands of hospitalization cases each year. Severe but often underrated infectious diseases, such as complicated nasal infections, are primarily caused by MRSA and S. epidermidis too. With the aim of studying new drugs with antimicrobial activity and effectiveness on drug resistant Staphylococcus strains, our attention in this study was drawn on the activity of a new association between two natural products: 5-pyrrolidone-2-carboxylic acid (PCA), naturally produced by certain Lactobacillus species, and copper sulfate pentahydrate (CS). The antimicrobial susceptibility test was conducted taking into account 12 different Staphylococcus strains, comprising 6 clinical isolates and 6 resistant strains. PCA 4%, w/w, and CS 0.002%, w/w, association in distilled water solution was found to have bactericidal activity against all tested strains. Antimicrobial kinetics highlighted that PCA 4%, w/w, and CS 0.002% association could reduce by 5 log10 viable bacterial counts of MRSA and oxacillin resistant S. epidennidis in less than 5 and 3 minutes respectively. Microscopic investigations suggest a cell wall targeting mechanism of action. Being very safe and highly tolerated, the natural product PCA and CS association proved to be a promising antimicrobial agent to treat Staphylococcus related infections.

  4. Putative relationship between hormonal status and serum pyrrolidone carboxypeptidase activity in pre- and post- menopausal women with breast cancer.

    PubMed

    Carrera-González, María del Pilar; Ramírez-Expósito, María Jesús; Dueñas, Basilio; Martínez-Ferrol, Julia; Mayas, María Dolores; Martínez-Martos, José Manuel

    2012-12-01

    In breast cancer, hormonal changes are rather constant in post-menopausal women since they tend to vary only over long time spans. However, in pre-menopausal women, the development of breast cancer is associated with hormonal physiological variations. The aim of the present work was to analyse the changes in circulating levels of gonadotropin-releasing hormone (GnRH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) in pre- and post-menopausal women that were healthy or with breast cancer, and their connection to serum pyrrolidone carboxypeptidase (Pcp) activity. We observed significant changes in the hormonal profile in post-menopausal women with breast cancer compared to the control group. In pre-menopausal women, we found significant changes in circulating GnRH levels with respect to the healthy group. Our present results support the existence of neuroendocrine misregulation that could be involved in tumour progression, with Pcp being a potentially new pharmacological target in breast cancer treatments.

  5. Recyclable and stable silver deposited magnetic nanoparticles with poly (vinyl pyrrolidone)-catechol coated iron oxide for antimicrobial activity.

    PubMed

    Mosaiab, Tamim; Jeong, Chan Jin; Shin, Gyo Jic; Choi, Kyung Ho; Lee, Sang Kug; Lee, Iksoo; In, Insik; Park, Sung Young

    2013-10-01

    This paper introduces a facile method to make highly stable and recyclable antimicrobial magnetic nanoparticles (NPs). Initially, magnetic iron oxide nanoparticles (IONPs) were coated with poly (vinyl pyrrolidone) conjugated catechol (PVP-CCDP). Afterward, silver nanoparticles (Ag(0)) were deposited onto PVP-CCDP coated IONPs using remain catechol. The prepared nanoparticles showed long term (~4 weeks) colloidal stability and redispersibility, respectively, against external magnetic field and over a broad range of pH (4-12). The NPs were characterized by UV-vis, SEM, XPS, and XRD measurements. TEM and DLS analyses showed that the mean particle size of PVP-CCDP coated IONPs/Ag(0) were about 72 nm. The recyclable magnetic NPs possessed a high antibacterial effect against the model microbes Staphylococcus aureus and Escherichia coli and could be separated easily using magnet following antibacterial test for repeated uses and maintained 100% antibacterial efficiency during three cycles. In MTT assay, the magnetic nanoparticles possessed no measureable cytotoxicity to live cells.

  6. Antifouling and antimicrobial polymer membranes based on bioinspired polydopamine and strong hydrogen-bonded poly(N-vinyl pyrrolidone).

    PubMed

    Jiang, Jinhong; Zhu, Liping; Zhu, Lijing; Zhang, Hongtao; Zhu, Baoku; Xu, Youyi

    2013-12-26

    A facile and versatile approach for the preparation of antifouling and antimicrobial polymer membranes has been developed on the basis of bioinspired polydopamine (PDA) in this work. It is well-known that a tightly adherent PDA layer can be generated over a wide range of material surfaces through a simple dip-coating process in dopamine aqueous solution. The resulting PDA coating is prone to be further surface-tailored and functionalized via secondary treatments because of its robust reactivity. Herein, a typical hydrophobic polypropylene (PP) porous membrane was first coated with a PDA layer and then further modified by poly(N-vinyl pyrrolidone) (PVP) via multiple hydrogen-bonding interactions between PVP and PDA. Data of water contact angle measurements showed that hydrophilicity and wettability of the membranes were significantly improved after introducing PDA and PVP layers. Both permeation fluxes and antifouling properties of the modified membranes were enhanced as evaluated in oil/water emulsion filtration, protein filtration, and adsorption tests. Furthermore, the modified membranes showed remarkable antimicrobial activity after iodine complexation with the PVP layer. The PVP layer immobilized on the membrane had satisfying long-term stability and durability because of the strong noncovalent forces between PVP and PDA coating. The strategy of material surface modification reported here is substrate-independent, and applicable to a broad range of materials and geometries, which allows effective development of materials with novel functional coatings based on the mussel-inspired surface chemistry.

  7. Study of Nucleate Pool Boiling Performance of 2,2,2-Trifluoroethanol (TFE)/n-Methyl-2-Pyrrolidone(NMP)

    NASA Astrophysics Data System (ADS)

    Kojima, Hiroshi; Oka, Masahiro; Akisawa, Atsushi; Kashiwagi, Takao

    The absorption heat pump using water-LiBr solution as working fluid has widely been used for air-conditioning system in Japan. However, it is difficult to apply the system for various uses, such as the utilization of low temperature heat sources, refrigeration and air-source type heat pumps because of the properties of the working fluid. 2,2,2- Trifluoroethanol (TFE) /n-Methyl-2- Pyrrolidone(NMP)is expected to be one of the most useful working fluids for the absorption heat pump of such use. While a number of investigations are available for the heat transfer performal1ce of LiBr solution, no work has been carried out to find out the heat transfer coefficient of TFE/NMP mixtures although it is important to know the heat transfer performance of TFE/NMP mixtures to design each element of the heat pump.In this study, nucleate pool boiling heat transfer cofficients are measured for TFE/NMP mixtures in order to evaluate the heat transfer perfonnance in the generator which is one of the element of the heat pump.

  8. Cooling Capacity Optimization: Calculation of Hardening Power of Aqueous Solution Based on Poly(N-Vinyl-2-Pyrrolidone)

    NASA Astrophysics Data System (ADS)

    Koudil, Z.; Ikkene, R.; Mouzali, M.

    2013-11-01

    Polymer quenchants are becoming increasingly popular as substitutes for traditional quenching media in hardening metallic alloys. Water-soluble organic polymer offers a number of environmental, economic, and technical advantages, as well as eliminating the quench-oil fire hazard. The close control of polymer quenchant solutions is essential for their successful applications, in order to avoid the defects of structure of steels, such as shrinkage cracks and deformations. The aim of the present paper is to evaluate and optimize the experimental parameters of polymer quenching bath which gives the best behavior quenching process and homogeneous microstructure of the final work-piece. This study has been carried out on water-soluble polymer based on poly(N-vinyl-2-pyrrolidone) PVP K30, which does not exhibit inverse solubility phenomena in water. The studied parameters include polymer concentration, bath temperature, and agitation speed. Evaluation of cooling power and hardening performance has been measured with IVF SmartQuench apparatus, using standard ISO Inconel-600 alloy. The original numerical evaluation method has been introduced in the computation software called SQ Integra. The heat transfer coefficients were used as input data for calculation of microstructural constituents and the hardness profile of cylindrical sample.

  9. Preparation, characterization and surface p Ka values of poly( N-vinyl-2-pyrrolidone)/chitosan blend films

    NASA Astrophysics Data System (ADS)

    Demirci, Serkan; Alaslan, Ali; Caykara, Tuncer

    2009-03-01

    Blend films of poly( N-vinyl-2-pyrrolidone) (PVP) and chitosan (CTS) were prepared by casting method from acetic acid solutions. All blend films obtained are optically clear to the naked eye. The structure and physical properties of the blend films were analyzed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), mechanical testing (Instron) and contact-angle measurements. The ATR-FTIR results indicated that there is no detectable band shifts at 1650 cm -1. From TGA studies, it was found that the onset degradation temperature of the blends almost unchanged due to the presence of a weak interaction between PVP and CTS chains. The DSC analysis showed a single glass transition temperature for all the blends, indicating that these polymers are miscible over the entire composition range. The mechanical properties of the blends, such as breaking stress and elongation at break and Young modulus were greatly affected with increase of CTS content. In addition, we found that the blends exhibit well defined contact angle titration curves from which the surface p Ka values were determined. In conclusion, these experimental findings provide fundamental knowledge for the preparation of bioreactive surfaces of controlled reactivity on CTS based blends.

  10. Cross-linked polyvinyl alcohol and method of making same

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  11. Structural-mechanical and thermophysical properties of modified polyvinyl chloride

    NASA Astrophysics Data System (ADS)

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

    1991-06-01

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

  12. Stability of polyvinyl alcohol-coated biochar nanoparticles in brine

    NASA Astrophysics Data System (ADS)

    Griffith, Christopher; Daigle, Hugh

    2017-01-01

    This paper reports on the dispersion stability of 150 nm polyvinyl alcohol coated biochar nanoparticles in brine water. Biochar is a renewable, carbon based material that is of significant interest for enhanced oil recovery operations primarily due to its wide ranging surface properties, low cost of synthesis, and low environmental toxicity. Nanoparticles used as stabilizing agents for foams (and emulsions) or in nanofluids have emerged as potential alternatives to surfactants for subsurface applications due to their improved stability at reservoir conditions. If, however, the particles are not properly designed, they are susceptible to aggregation because of the high salinity brines typical of oil and gas reservoirs. Attachment of polymers to the nanoparticle surface, through covalent bonds, provides steric stabilization, and is a necessary step. Our results show that as the graft density of polyvinyl alcohol increases, so too does the stability of nanoparticles in brine solutions. A maximum of 34 wt% of 50,000 Da polyvinyl alcohol was grafted to the particle surface, and the size of the particles was reduced from 3500 nm (no coating) to 350 nm in brine. After 24 h, the particles had a size of 500 nm, and after 48 h completely aggregated. 100,000 Da PVA coated at 24 wt% on the biochar particles were stable in brine for over 1 month with no change in mean particle size of 330 nm.

  13. Polyvinyl pyrrolidone-coated silver nanoparticles in a human lung cancer cells: time- and dose-dependent influence over p53 and caspase-3 protein expression and epigenetic effects.

    PubMed

    Blanco, Jordi; Lafuente, Daisy; Gómez, Mercedes; García, Tánia; Domingo, José L; Sánchez, Domènec J

    2017-02-01

    The present study was aimed at providing a better understanding of the influence of silver nanoparticles (AgNPs) on the p53 tumor suppressor protein. Cell line A549 was exposed to a range of concentrations of AgNPs, and a time course (up to 72 h) of cell viability was determined. We also determined the time course of gene and protein expression of p53, p21, murine double minute 2 (MDM2) and caspase-3. The expression of all of these proteins was also determined after daily exposure of the cells to 10 µg/mL of AgNPs for 7 days, or after discontinuous exposure by treating the cells every 3 days, for 15 or 30 days. Moreover, epigenetic changes in the acetylation of the histone H3 protein and in global DNA methylation patterns were determined after 72 h of exposure. Results showed that daily exposure to low doses of AgNPs, or a single exposure to high concentrations for 72 h, decreased gene and protein expression of p53, p21, MDM2 and caspase-3 in A549 cells. In contrast, a discontinuous exposure to low doses or a single exposure to low concentrations for 72 h increased the levels of the active forms of p53 and caspase-3, as well as the p21 and MDM2 protein levels. In addition, exposure to high concentrations of AgNPs for 72 h induced higher levels of global DNA methylation and global histone H3 deacetylation in A549 cells. These results provide new information on the toxic action of AgNPs.

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

    SciTech Connect

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

    2008-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  16. Poly(N-vinyl-2-pyrrolidone) elution from polysulfone dialysis membranes by varying solvent and wall shear stress.

    PubMed

    Namekawa, Koki; Matsuda, Masato; Fukuda, Makoto; Kaneko, Ami; Sakai, Kiyotaka

    2012-06-01

    Some dialysis patients are treated with post-hemodiafiltration (HDF); the blood viscosity of the patients who undergo post-HDF is higher than that of the patients who undergo conventional hemodialysis. This study aims to evaluate poly(N-vinyl-2-pyrrolidone) (PVP) elution from PSf dialysis membranes by varying solvents and high wall shear stress caused by blood viscosity. We tested three commercial membranes: APS-15SA (Asahi Kasei Kuraray), CX-1.6U (Toray) and FX140 (Fresenius). Dialysate and blood sides of the dialyzers were primed with reverse osmosis (RO) water and saline. RO water, saline and dextran solution (2.9 and 5.8 mPa s) were circulated in the blood side. The amount of eluted PVP was determined by 0.02 N iodometry. The hardness and adsorption force of human serum albumin (HSA) on the membrane surfaces were measured by the atomic force microscope. When wall shear stress was increased using dextran, the amount of PVP eluted by the 2.9 mPa s solution equaled that eluted by the 5.8 mPa s solution with APS-15SA and CX-1.6U sterilized by gamma rays. The amount of PVP eluted by the 5.8 mPa s solution was higher than that eluted by the 2.9 mPa s solution with FX140 sterilized by autoclaving. The wall shear stress increased the PVP elution from the surface, hardness and adsorption force of HSA. Sufficient gamma-ray irradiation is effective in decreasing PVP elution.

  17. Effects of poly(2-hydroxyethyl methacrylate) and poly(vinyl-pyrrolidone) hydrogel implants on myopic and normal chick sclera

    PubMed Central

    Su, James; Iomdina, Elena; Tarutta, Elena; Ward, Brian; Song, Jie; Wildsoet, Christine F.

    2008-01-01

    There has been generally little attention paid to the utilization of biomaterials as an anti-myopia treatment. The purpose of this study was to investigate whether polymeric hydrogels, either implanted or injected adjacent to the outer scleral surface, slow ocular elongation. White Leghorn (gallus gallus domesticus) chicks were used at 2 weeks of age. Chicks had either (1) strip of poly(2-hydroxyethyl methacrylate) (pHEMA) implanted monocularly against the outer sclera at the posterior pole, or (2) an in situ polymerizing gel [main ingredient: poly(vinyl-pyrrolidone) (PVP)] injected monocularly at the same location. Some of the eyes injected with the polymer were fitted with a diffuser or a −10D lens. In each experiment, ocular lengths were measured at regular intervals by high frequency A-scan ultrasonography, and chicks were sacrificed for histology at staged intervals. No in vivo signs of either orbital or ocular inflammation were observed. The pHEMA implant significantly increased scleral thickness by the third week, and the implant became encapsulated with fibrous tissue. The PVP-injected eyes left otherwise untreated, showed a significant increase in scleral thickness, due to increased chondrocyte proliferation and extracellular matrix deposition. However, there was no effect of the PVP injection on ocular elongation. In eyes wearing optical devices, there was no effect on either scleral thickness or ocular elongation. These results represent “proof of principle” that scleral growth can be manipulated without adverse inflammatory responses. However, since neither approach slowed ocular elongation, additional factors must influence scleral surface area expansion in the avian eye. PMID:19109950

  18. The structural organization of N-methyl-2-pyrrolidone + water mixtures: A densitometry, x-ray diffraction, and molecular dynamics study

    SciTech Connect

    Usula, M.; Marincola, F. Cesare; Porcedda, S.; Mocci, F.; Gontrani, L.; Caminiti, R.

    2014-03-28

    A combined approach of molecular dynamics simulations, wide angle X-ray scattering experiments, and density measurements was employed to study the structural properties of N-methyl-2-pyrrolidone (NMP) + water mixtures over the whole concentration range. Remarkably, a very good agreement between computed and experimental densities and diffraction patterns was achieved, especially if the effect of the mixture composition on NMP charges is taken into account. Analysis of the intermolecular organization, as revealed by the radial and spatial distribution functions of relevant solvent atoms, nicely explained the density maximum observed experimentally.

  19. Poly(anhydride-ester) and poly(N-vinyl-2-pyrrolidone) blends: salicylic acid-releasing blends with hydrogel-like properties that reduce inflammation.

    PubMed

    Ouimet, Michelle A; Fogaça, Renata; Snyder, Sabrina S; Sathaye, Sameer; Catalani, Luiz H; Pochan, Darrin J; Uhrich, Kathryn E

    2015-03-01

    Polymers such as poly(N-vinyl-2-pyrrolidone) (PVP) have been used to prepare hydrogels for wound dressing applications but are not inherently bioactive. For enhanced healing, PVP was blended with salicylic acid-based poly(anhydride-esters) (SAPAE) and shown to exhibit hydrogel properties upon swelling. In vitro release studies demonstrated that the chemically incorporated drug (SA) was released from the polymer blends over 3-4 d in contrast to 3 h, and that blends of higher PVP content displayed greater swelling values and faster SA release. The polymer blends significantly the inflammatory cytokine, TNF-α, in vitro without negative effects.

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

    NASA Astrophysics Data System (ADS)

    Shah, Bhavesh

    This dissertation focuses on overcoming existing limitations of WPCs which prevent them from realizing their full market potential. These limitations include: (i) lack of a continuous extrusion process for microcellular foaming of polyvinyl chloride (PVC) and its composites using supercritical fluids to reduce the high density of the WPCs, (ii) need for an efficient coupling agent for WPCs to overcome the poor compatibility between wood and plastic, and (iii) unproven use of wood as a filler for the biopolymer polylactide (PLA) to make "green" composites. These limitations were addressed through experimentation to develop a continuous extrusion process for microcellular foaming, and through surface modification of wood flour using natural coupling agents. The effects of wood flour, acrylic modifier and plasticizer content on the rheological properties of PVC based WPCs were studied using an extrusion capillary rheometer and a two-level factorial design. Wood flour content and acrylic modifier content were the major factors affecting the die swell ratio. Addition of plasticizer decreased the true viscosity of unfilled and filled PVC, irrespective of the acrylic modifier content. However, the addition of acrylic modifier significantly increased the viscosity of unfilled PVC but decreased the composite viscosity. Results of the rheological study were used to set baseline conditions for the continuous extrusion foaming of PVC WPCs using supercritical CO 2. Effects of material composition and processing conditions on the morphology of foamed samples were investigated. Foamed samples were produced using various material compositions and processing conditions, but steady-state conditions could not be obtained for PVC. Thus the relationships could not be determined. Incompatibility between wood flour and PVC was the focus of another study. The natural polymers chitin and chitosan were used as novel coupling agents to improve interfacial adhesion between the polymer matrix

  1. Electrical and Thermal Properties of Polyvinyl Acetal Based Nanocomposites

    SciTech Connect

    Sauers, Isidor; James, David Randy; Ellis, Alvin R; Tuncer, Enis; Polyzos, Georgios; Pace, Marshall O

    2009-10-01

    A water chemistry procedure is used to synthesize titanium dioxide nanoparticles which can later be blended with a polymer to form a nanodielectric. The synthesized nanoparticles are dispersed in two grades of polyvinyl acetal (commercially available under the trade names BX-L and KS-10, manufactured by SEKISUI Chemicals). Nanocomposite materials were prepared with 15 and 33 wt% titanium dioxide. The variation of the glass transition temperature with increasing filler weight fraction is presented. The dielectric breakdown strengths of the nanodielectric samples are reported. The presented results can be employed to optimize the dielectric properties of the studied nanocomposites for potential use in cryogenic high voltage applications.

  2. Polyvinyl alcohol doped with nickel chloride hexahydrate as conductor polymer

    NASA Astrophysics Data System (ADS)

    Ruiz-Limon, B.; Olivares-Perez, Arturo; Silva-Andrade, F.; Fuentes-Tapia, I.; Ibarra-Torres, Juan Carlos

    2004-06-01

    Polyvinyl alcohol is a viscous solution, with blue clear appearance, not has odor, when is deposited, as a film dry the appearance is clear transparent and has high flexibility. This polymer no has double link and don not has p orbital that permit the conductivity. However, can be doped with salts as ammonium dichromate and nickel chloride hexahydrate NiCl26H2O constructing a good conductor polymer with a resistivity around 300 ohms cm. Conserving the high flexibility opened new possibilities and applications.

  3. Electromagnetic and microwave-absorbing properties of magnetite decorated multiwalled carbon nanotubes prepared with poly(N-vinyl-2-pyrrolidone)

    SciTech Connect

    Zhao, Chunying; Zhang, Aibo; Zheng, Yaping; Luan, Jingfan

    2012-02-15

    Graphical abstract: The Fe{sub 3}O{sub 4}/MWNTs hybrids prepared with PVP achieve a maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below -10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe{sub 3}O{sub 4}/MWNTs hybrids have better absorption properties in the high-frequency range. Highlight: Black-Right-Pointing-Pointer The Fe{sub 3}O{sub 4} decorated MWNTs hybrids were prepared using PVP as dispersant. Black-Right-Pointing-Pointer Many more Fe{sub 3}O{sub 4} particles were attached homogeneously on the surface of MWNTs. Black-Right-Pointing-Pointer The Fe{sub 3}O{sub 4}/MWNTs hybrids achieve a maximum reflection loss of -35.8 dB at 8.56 GHz. Black-Right-Pointing-Pointer A new reflection loss peak occurs at the high-frequency of 14.6 GHz. -- Abstract: The magnetite (Fe{sub 3}O{sub 4}) decorated multiwalled carbon nanotubes (MWNTs) hybrids were prepared by an in situ chemical precipitation method using poly(N-vinyl-2-pyrrolidone) (PVP) as dispersant. The structure and morphology of hybrids are characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and transmission electron-microscopy (TEM). The TEM investigation shows that the Fe{sub 3}O{sub 4}/MWNTs hybrids exhibit less entangled structure and many more Fe{sub 3}O{sub 4} particles are attached homogeneously on the surface of MWNTs, which indicated that PVP can indeed help MWNTs to disperse in isolated form. The electromagnetic and absorbing properties were investigated in a frequency of 2-18 GHz. The results show that the Fe{sub 3}O{sub 4}/MWNTs hybrids exhibit a superparamagnetic behavior and possess a saturation magnetization of 22.9 emu/g. The maximum reflection loss is -35.8 dB at 8.56 GHz, and the bandwidth below -10 dB is more than 2.32 GHz. More importantly, a new reflection loss peak occurs at the frequency of 14.6 GHz, which indicates that the Fe{sub 3}O{sub 4}/MWNTs

  4. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... chloride plants. 61.64 Section 61.64 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of this section and § 61.65....

  5. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... chloride plants. 61.64 Section 61.64 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of this section and § 61.65....

  6. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... chloride plants. 61.64 Section 61.64 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of this section and § 61.65....

  7. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... chloride plants. 61.64 Section 61.64 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of this section and § 61.65....

  8. 40 CFR 61.64 - Emission standard for polyvinyl chloride plants.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... chloride plants. 61.64 Section 61.64 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED... Standard for Vinyl Chloride § 61.64 Emission standard for polyvinyl chloride plants. An owner or operator of a polyvinyl chloride plant shall comply with the requirements of this section and § 61.65....

  9. 77 FR 14342 - Polyvinyl Alcohol From Taiwan: Correction to Notice of Opportunity To Request Administrative Review

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-09

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF COMMERCE International Trade Administration Polyvinyl Alcohol From Taiwan: Correction to Notice of Opportunity To Request... antidumping duty order on polyvinyl alcohol from Taiwan. See Antidumping or Countervailing Duty Order,...

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

    SciTech Connect

    Yamamoto, Kikuo; Maehala, Takashi; Mitani, Katsuo; Mizutani, Yukio )

    1993-11-05

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

  11. 78 FR 37794 - Polyvinyl Alcohol from Taiwan: Final Results of Antidumping Duty Administrative Review; 2010-2012

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-24

    ... International Trade Administration Polyvinyl Alcohol from Taiwan: Final Results of Antidumping Duty... results of the administrative review of the antidumping duty order on polyvinyl alcohol (PVA) from Taiwan... February 29, 2012. \\1\\ See Polyvinyl Alcohol From Taiwan: Preliminary Results of Antidumping...

  12. In-situ formation of silver nanoparticles on poly (lactic acid) film by γ-radiation induced grafting of N-vinyl pyrrolidone.

    PubMed

    Wang, Jingxia; Chen, Hao; Chen, Zhuping; Chen, Yuheng; Guo, Dan; Ni, Maojun; Liu, Siyang; Peng, Chaorong

    2016-06-01

    A fast, easy and novel method for preparing biodegradable polymer films with silver nanoparticles was investigated to endow the material with excellent biocompatibility and antibacterial property. Silver nanoparticles (Ag NPs) were immobilized on the surface of polylactic acid (PLA) film by gamma radiation induced grafting of N-vinyl pyrrolidone (NVP). In this method, poly (N-vinyl pyrrolidone) (PVP) was produced and grafted onto the surface of PLA film by gamma radiation polymerization of NVP. PVP acted as both a bridge to connect the Ag NPs with the PLA film, and a stabilizer to protect the Ag NPs from agglomeration. The effect of various reaction parameters, including NVP/Ag mole ratio and radiation dose, on the fabrication of PLA-g-NVP/Ag film was demonstrated. Moreover, the interaction between PVP and Ag NPs was studied by X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy, that revealed the Ag NPs coordinated through the oxygen atom on the carbonyl group of PVP at 15 kGy radiation dose, but through the nitrogen atom and the oxygen atom of the amide group of PVP at 1 kGy dose.

  13. [Monograph for N-Methyl-pyrrolidone (NMP) and human biomonitoring values for the metabolites 5-Hydroxy-NMP and 2-Hydroxy-N-methylsuccinimide].

    PubMed

    2015-10-01

    1-Methyl-pyrrolidone (NMP) is used as a solvent in many technical applications. The general population may be exposed to NMP from the use as ingredient in paint and graffiti remover, indoors also from use in paints and carpeting. Because of developmental toxic effects, the use of NMP in consumer products in the EU is regulated. The developmental effects accompanied by weak maternally toxic effects in animal experiments are considered as the critical effects by the German HBM Commission. Based on these effects, HBM-I values of 10 mg/l urine for children and of 15 mg/l for adults, respectively, were derived for the metabolites 5-Hydroxy-NMP and 2-Hydroxy-N-methylsuccinimide. HBM-II-values were set to 30 mg/l urine for children and 50 mg/l for adults, respectively. Because of similar effects of the structural analogue 1-ethyl-2-pyrrolidone (NEP), the possible mixed exposure to both compounds has to be taken into account when evaluating the total burden.

  14. Methods of making pyrrolidones

    DOEpatents

    Werpy, Todd; Frye, Jr., John G.; Wang, Yong; Zacher, Alan H.

    2004-03-16

    The present invention provides methods for making N-methylpyrrolidine and analogous compounds via hydrogenation. Novel catalysts for this process, and novel conditions/yields are also described. Other process improvements may include extraction and hydrolysis steps. Some preferred reactions take place in the aqueous phase. Starting materials for making N-methylpyrrolidine may include succinic acid, N-methylsuccinimide, and their analogs.

  15. Methods Of Making Pyrrolidones

    DOEpatents

    Werpy, Todd; Frye, Jr., John G.; Wang, Yong; Zacher, Alan H.

    2003-12-30

    The present invention provides methods for making N-methylpyrrolidine and analogous compounds via hydrogenation. Novel catalysts for this process, and novel conditions/yields are also described. Other process improvements may include extraction and hydrolysis steps. Some preferred reactions take place in the aqueous phase. Starting materials for making N-methylpyrrolidine may include succinic acid, N-methylsuccinimide, and their analogs.

  16. Methods of making pyrrolidones

    DOEpatents

    Werpy, Todd; Frye, Jr., John G.; Wang, Yong; Zacher, Alan H.

    2003-10-14

    The present invention provides methods for making N-methylpyrrolidine and analogous compounds via hydrogenation. Novel catalysts for this process, and novel conditions/yields are also described. Other process improvements may include extraction and hydrolysis steps. Some preferred reactions take place in the aqueous phase. Starting materials for making N-methylpyrrolidine may include succinic acid, N-methylsuccinimide, and their analogs.

  17. Methods of making pyrrolidones

    DOEpatents

    Werpy, Todd; Frye, Jr., John G.; Wang, Yong; Zacher, Alan H.

    2003-08-05

    The present invention provides methods for making N-methylpyrrolidine and analogous compounds via hydrogenation. Novel catalysts for this process, and novel conditions/yields are also described. Other process improvements may include extraction and hydrolysis steps. Some preferred reactions take place in the aqueous phase. Starting materials for making N-methylpyrrolidine may include succinic acid, N-methylsuccinimide, and their analogs.

  18. Optical Fiber Relative-Humidity Sensor with Polyvinyl Alcohol Film

    NASA Astrophysics Data System (ADS)

    Gastón, Ainhoa; Pérez, Fátima; Sevilla, Joaquín

    2004-07-01

    We describe a fiber-optic relative-humidity (RH) sensor comprising a moisture-sensitive overlay on a single-mode side-polished fiber. The hygroscopic polymeric material deposited was polyvinyl alcohol (PVA), which proved to have good adherence and stability. The film reached a fast equilibrium with atmospheric moisture (in less than 1 min), inducing changes in the output optical power of ~10 dB for the 70%-90% RH range. To yield a low-cost device, single-mode standard communication fibers were used; therefore all the components of the sensor can be commercial, mass-produced telecommunication devices. The experimental results obtained are consistent with the expected behavior of the system; the output power decreases because of losses in the polished region of the fiber as the refractive index of its external medium approaches the fiber core value. Because the external medium is PVA film, its refractive index changes in response to its water content.

  19. [Determination of organotin compounds in polyvinyl chloride toys].

    PubMed

    Ohno, Hiroyuki; Suzuki, Masako; Aoyama, Taiki; Mitani, Kazunori

    2003-08-01

    Organotin compounds in polyvinyl chloride toys were determined by GC/MS after ethyl derivatization with sodium tetraethylborate. The samples were 12 balls, 12 soft toys, 10 food toys and 13 face masks for children. Monooctyltin, dioctyltin and trioctyltin compounds were found in all face masks at the levels of 74.8-917 micrograms/g. 474-3,960 micrograms/g and 1.0-213 micrograms/g, respectively. They also were detected in 6 balls, 4 soft toys and 1 food toy. Monomethyltin and dimethyltin compounds were found in 8 face masks at the levels of 40.9-227 micrograms/g and 222-1,450 micrograms/g, respectively. Monobutyltin and dibutyltin (DBT) compounds were found in 1 ball, 3 food toys and 5 face masks. In particular, 1 ball and 4 face masks contained toxic DBT at the levels of 527-999 micrograms/g.

  20. Evaluation of a Polyvinyl Toluene Neutron Counter Array

    SciTech Connect

    Robert Hayes

    2008-03-01

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

  1. Immobilization of enzyme into poly(vinyl alcohol) membrane

    SciTech Connect

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

    1986-11-01

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

  2. Surface Sulfonation of Polyvinyl Chloride by Plasma for Antithrombogenicity

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Chen, Yashao

    2004-06-01

    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.

  3. [Test method for 6 phthalates in polyvinyl chloride].

    PubMed

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

    2011-01-01

    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.

  4. Friction loss in straight pipes of unplasticized polyvinyl chloride.

    PubMed

    Iwasaki, T; Ojima, J

    1996-01-01

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

  5. End-of-life of starch-polyvinyl alcohol biopolymers.

    PubMed

    Guo, M; Stuckey, D C; Murphy, R J

    2013-01-01

    This study presents a life cycle assessment (LCA) model comparing the waste management options for starch-polyvinyl alcohol (PVOH) biopolymers including landfill, anaerobic digestion (AD), industrial composting and home composting. The ranking of biological treatment routes for starch-PVOH biopolymer wastes depended on their chemical compositions. AD represents the optimum choice for starch-PVOH biopolymer containing N and S elements in global warming potential (GWP(100)), acidification and eutrophication but not on the remaining impact categories, where home composting was shown to be a better option due to its low energy and resource inputs. For those starch-PVOH biopolymers with zero N and S contents home composting delivered the best environmental performance amongst biological treatment routes in most impact categories (except for GWP(100)). The landfill scenario performed generally well due largely to the 100-year time horizon and efficient energy recovery system modeled but this good performance is highly sensitive to assumptions adopted in landfill model.

  6. Polyvinyl chloride meat-wrapping film study. Final report

    SciTech Connect

    Vandervort, R.

    1988-01-01

    As a result of worker complaints in the Baltimore, Maryland area, potential health hazards associated with the use of polyvinyl-chloride film for wrapping meat were reviewed. Fumes generated during the meat-wrapping process were causing concern among the workers as they experienced respiratory irritation and distress. It appeared that only some of the meat wrappers experienced difficulty, only some of the rolls of film-produced irritations in the affected workers, and affected workers had prior histories of respiratory difficulties. Fumes were generated during hot-wire film cutting. The amount of fume generated depended significantly on the care taken during the operation. If the dispensing machines were improperly adjusted, large amounts of fumes could be obtained during the cutting process. The author concludes that the amounts of these chemicals released during this operation does not constitute a health hazard to the employees. It may be necessary, however, to remove persons with prior respiratory irritation from this particular job location.

  7. [Use of polyvinyl alcohol for preparing frozen histological sections].

    PubMed

    Serga, V A; Bykov, L A; Kasatonov, V G

    1982-01-01

    The authors developed a new method for preparation of frozen histological sections. It consists in the use of glycerin-plastified polymer, polyvinyl alcohol, and distilled water for impregnation of tissue pieces and subsequent freezing of them in the same medium. This produces histological sections of high quality. The frozen sections are sufficiently thin (3--5 micrometers). The method excludes cell structure destruction by ice crystals and overfreezing of blocks; the sections do not crumble. Losses of free cell elements, extraction of substances and other artifacts are minimized. The frozen histological sections are firmly glued to the glass without using protein with glycerin. The method saves time and reagents for the preparation of the sections and allows their wide use in morphological and histochemical studies.

  8. Cross-linked polyvinyl alcohol films as alkaline battery separators

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

    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.

  9. Polyvinyl alcohol coating of polystyrene inertial confinement fusion targets

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  10. Cross-linked polyvinyl alcohol films as alkaline battery separators

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

    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.

  11. In situ self cross-linking of polyvinyl alcohol battery separators

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    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.

  12. Growth characteristics of selected fungi on polyvinyl film

    SciTech Connect

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

    1986-04-01

    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.

  13. Simultaneous radiation induced graft polymerization of N-vinyl-2-pyrrolidone onto polypropylene non-woven fabric for improvement of blood compatibility

    NASA Astrophysics Data System (ADS)

    Li, Rong; Wang, Hengdong; Wang, Wenfeng; Ye, Yin

    2013-07-01

    In this study, N-vinyl-2-pyrrolidone (NVP) was grafted onto polypropylene non-woven fabric (PPNWF) through a simultaneous irradiation induced graft polymerization technique. Effect of the parameters of graft polymerization, i.e., monomer concentration, absorbed dose and dose rate, on the degree of grafting (DG) was investigated. The graft polymerization of NVP was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). A contact angle goniometry was used to test water contact angle (WCA) of original PPNWF and modified samples. The in vitro blood compatibility, including hemolysis, protein adsorption, platelet adhesion and activated partial thromboplastin time (APTT) of tested specimens, was evaluated. The results demonstrated that the hemocompatibility of PPNWF was improved via graft polymerization of NVP.

  14. Thermal stability of polyvinyl alcohol/nanocrystalline cellulose composites.

    PubMed

    Voronova, Marina I; Surov, Oleg V; Guseinov, Sabir S; Barannikov, Vladimir P; Zakharov, Anatoly G

    2015-10-05

    Thermal stability of polyvinyl alcohol/cellulose nanocrystals (PVA/CNCs) composites prepared with solution casting technique was studied. The PVA/CNCs composites were characterized by Fourier transform infrared spectrometry, X-ray diffraction, differential scanning calorimeter (DSC) and thermogravimetric (TG) analysis. Due to the presence of CNCs nanoparticles, thermal degradation of the composites occurs at much higher temperatures compared to that of the neat PVA. Thermal stability of the PVA/CNCs composites is maximally enhanced with CNCs content of 8-12 wt%. Some thermal degradation products of the PVA/CNCs composites were identified by mass spectrometric analysis. TG measurements with synchronous recording of mass spectra revealed that the thermal degradation of both CNCs and PVA in the composites with CNCs content of 8-12 wt% occurs simultaneously at a much higher temperature than that of CNCs or the neat PVA. However, with increasing CNCs content more than 12 wt% the thermal stability of the composites decreases. In this case, the degradation of CNCs comes first followed by the degradation of PVA.

  15. UV-responsive polyvinyl alcohol nanofibers prepared by electrospinning

    NASA Astrophysics Data System (ADS)

    Khatri, Zeeshan; Ali, Shamshad; Khatri, Imran; Mayakrishnan, Gopiraman; Kim, Seong Hun; Kim, Ick-Soo

    2015-07-01

    We report UV-responsive polyvinyl alcohol (PVA) nanofibers for potential application for recording and erasing quick response (QR) codes. We incorporate 1‧-3‧-dihydro-8-methoxy-1‧,3‧,3‧-trimethyl-6-nitrospiro [2H-1-benzopyran-2,2‧-(2H)-indole] (indole) and,3-dihydro-1,3,3-trimethylspiro [2H-indole-2,3‧-[3H] phenanthr [9,10-b] (1,4) oxazine] (oxazine) into PVA polymer matrix via electrospinning technique. The resultant nanofibers were measured for recording-erasing, photo-coloration and thermal reversibility. The rate of photo-coloration of PVA-indole nanofibers was five times higher than the PVA-oxazine nanofibers, whereas the thermal reversibility found to be more than twice as fast as PVA-oxazine nanofibers. Results showed that the resultant nanofibers have very good capability of recording QR codes multiple times. The FTIR spectroscopy and SEM were employed to characterize the electrospun nanofibers. The UV-responsive PVA nanofibers have great potentials as a light-driven nanomaterials incorporated within sensors, sensitive displays and in optical devices such as erasable and rewritable optical storage.

  16. Pressure loss in elbow pipes of unplasticized polyvinyl chloride.

    PubMed

    Iwasaki, T; Ojima, J

    1996-01-01

    In the ductwork of local exhaust systems, 90 degrees elbow pipes (JIS K 6739) are commonly used to alter the direction of airflow; thus, are important components of polyvinyl chloride (PVC) ducts. Pressure loss in 90 degrees PVC elbow pipes was investigated by measuring static pressure, and the characteristics of airflow was determined. First, a linear decrease in static pressure was observed at points of the downstream side beyond a distance of 10 times the diameter (10d) from the flanged round opening of the smooth VU ducts (JIS K6741). The linear decrease was also observed at points of the downstream side located at distances of greater than 30d from the elbow pipe. Coefficients of loss in the PVC elbow pipes were found to be constant for the Reynolds numbers ranging from 3.38 x 10(4) to 5.96 x 10(5) for all diameters examined, and a chart of pressure loss was constructed with these coefficients. The coefficients of loss in PVC elbow pipes were not equivalent to those of metal stamped elbows for any R/d. However, the differences in the coefficients between the metal stamped elbow and the PVC elbow were smaller with larger R/d values.

  17. Dielectric breakdown during Cs+ sputtering of polyvinyl chloride

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  18. Electrospun chitosan/polyvinyl alcohol nanofibre mats for wound healing.

    PubMed

    Charernsriwilaiwat, Natthan; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Opanasopit, Praneet

    2014-04-01

    Chitosan (CS) aqueous salt blended with polyvinyl alcohol (PVA) nanofibre mats was prepared by electrospinning. CS was dissolved with hydroxybenzotriazole (HOBt), thiamine pyrophosphate (TPP) and ethylenediaminetetraacetic acid (EDTA) in distilled water without the use of toxic or hazardous solvents. The CS aqueous salts were blended with PVA at different weight ratios, and the effect of the solution ratios was investigated. The morphologies and mechanical and swelling properties of the generated fibres were analysed. Indirect cytotoxicity studies indicated that the CS/PVA nanofibre mats were non-toxic to normal human fibroblast cells. The CS-HOBt/PVA and CS-EDTA/PVA nanofibre mats demonstrated satisfactory antibacterial activity against both gram-positive and gram-negative bacteria, and an in vivo wound healing test showed that the CS-EDTA/PVA nanofibre mats performed better than gauze in decreasing acute wound size during the first week after tissue damage. In conclusion, the biodegradable, biocompatible and antibacterial CS-EDTA/PVA nanofibre mats have potential for use as wound dressing materials.

  19. Self Nucleation and Crystallization of Poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Thomas, David; Cebe, Peggy

    Polyvinyl alcohol (PVA) is a hydrophilic, biodegradable, semi-crystalline polymer with uses ranging from textiles to medicine. Film samples of PVA were investigated to assess crystallization and melting behavior during self-nucleation experiments, and thermal degradation, using differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis, respectively. TG results show that degradation occurred at temperatures close to the observed peak melting temperature of 223 C. Using conventional DSC, PVA was heated at a rate of 10 C/min to various self-nucleation temperatures, Ts, within its melting range, briefly annealed, cooled and reheated. Three distinct crystallization regimes were observed upon cooling, depending upon self nucleation temperature. At low values of Ts, below 227 C, PVA only partially melts; residual crystal anneals while new, less perfect crystals form during cooling. Between 228 C and 234 C, PVA was found to crystallize exclusively by self-nucleation. For Ts above 235 C the PVA melts completely. Fast scanning chip-based calorimetry was used to heat and cool at 2000 K/s, to prevent degradation. Results of self nucleation experiments using fast scanning and conventional DSC will be compared. NSF DMR-1206010.

  20. Respiratory illness caused by overheating of polyvinyl chloride.

    PubMed Central

    Froneberg, B; Johnson, P L; Landrigan, P J

    1982-01-01

    On 9 August 1979, 62 (30.8%) of 201 workers and one of 60 management personnel in a polyvinyl chloride (PVC) fabricating plant developed acute upper and lower respiratory irritation, headache, nausea, and fainting. All were taken to hospital; none died. Sixty of the patients were women. Interviews two weeks later with 57 affected and 14 unaffected workers disclosed that illness had followed exposure to fumes from an overheated (362 degrees C) PVC extruding machine. Fumes were emitted from 1100 until 1150; cases occurred from 1100 until late afternoon. All workers who became ill worked west of the overheated extruder, and the affected manager had visited that area. The earliest cases occurred closest to the machine, and incidence decreased (from 53.3% to 15.4%) with distance westward. This pattern was consistent with plant ventilation. Incidence rates in men and women did not differ (p greater than 0.1). At two and 14 weeks, pulmonary function testing of workers with persistent pulmonary symptoms showed abnormalities in 13 of 16 and in 9 of 11 respectively; the group with persistent symptoms contained an excess of non-smokers and of those with previous respiratory illnesses. One kilogram of PVC heated to 300 degrees C releases an estimated 12.9 g of hydrochloric acid (HCl) and 4.9 g of carbon monoxide (CO). We attributed the outbreak to exposure to toxic HCl and CO and rejected the hypothesis of mass psychogenic illness. PMID:7093150

  1. Poly(vinyl alcohol) gels as photoacoustic breast phantoms revisited

    NASA Astrophysics Data System (ADS)

    Xia, Wenfeng; Piras, Daniele; Heijblom, Michelle; Steenbergen, Wiendelt; van Leeuwen, Ton G.; Manohar, Srirang

    2011-07-01

    A popular phantom in photoacoustic imaging is poly(vinyl alcohol) (PVA) hydrogel fabricated by freezing and thawing (F-T) aqueous solutions of PVA. The material possesses acoustic and optical properties similar to those of tissue. Earlier work characterized PVA gels in small test specimens where temperature distributions during F-T are relatively homogeneous. In this work, in breast-sized samples we observed substantial temperature differences between the shallow regions and the interior during the F-T procedure. We investigated whether spatial variations were also present in the acoustic and optical properties. The speed of sound, acoustic attenuation, and optical reduced scattering coefficients were measured on specimens sampled at various locations in a large phantom. In general, the properties matched values quoted for breast tissue. But while acoustic properties were relatively homogeneous, the reduced scattering was substantially different at the surface compared with the interior. We correlated these variations with gel microstructure inspected using scanning electron microscopy. Interestingly, the phantom's reduced scattering spatial distribution matches the optical properties of the standard two-layer breast model used in x ray dosimetry. We conclude that large PVA samples prepared using the standard recipe make excellent breast tissue phantoms.

  2. Composition analysis and characterization of waste polyvinyl chloride (PVC) recovered from data cables.

    PubMed

    Suresh, Sunil S; Mohanty, Smita; Nayak, Sanjay K

    2017-02-01

    Cables and wires are the indispensable parts of electronic equipments for transmission of both information and electricity. Nowadays, data cables are widely used in the computer equipments for sending information and they become waste once its life cycle is completed. However, recycling of cables and wires are mainly concentrating into the recovery of metals such as aluminium and copper, rather than other polymer present. Polymeric materials from the waste data cables are often disposed into landfills or incinerated, since they have only lower value in recycling yard. From the data cables collected, it has been estimated that the major constituents are copper (58.3%), polyvinyl chloride (19.9%) and polyethylene (16%). Similarly, polycarbonate (2.9%), silicon rubber (1.6%), steel (1.4%) and other material (0.4%) such as cotton cord were also present as minor components. Out of these, polyvinyl chloride is the dominant polymer present in data cables. Hence, the present work investigates the reprocessability of the polyvinyl chloride recovered from the data cables and deals with issues such as premature degradation during life cycle, assessment of plasticizers and degradation after reprocessing. Torque measurement studies using torque rheometer revealed further mechanical recycling possibilites of the recovered polyvinyl chloride. Besides, the applicability of melt blending technique for processing recovered polyvinyl chloride can be found out by analysing thermal behaviour by using thermogravimetric analysis, differential scanning calorimetry and heat distortion temperature.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

    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.

  4. Polyvinyl chloride plastisol breast phantoms for ultrasound imaging.

    PubMed

    de Carvalho, Isabela Miller; De Matheo, Lucas Lobianco; Costa Júnior, José Francisco Silva; Borba, Cecília de Melo; von Krüger, Marco Antonio; Infantosi, Antonio Fernando Catelli; Pereira, Wagner Coelho de Albuquerque

    2016-08-01

    Ultrasonic phantoms are objects that mimic some features of biological tissues, allowing the study of their interactions with ultrasound (US). In the diagnostic-imaging field, breast phantoms are an important tool for testing performance and optimizing US systems, as well as for training medical professionals. This paper describes the design and manufacture of breast lesions by using polyvinyl chloride plastisol (PVCP) as the base material. Among the materials available for this study, PVCP was shown to be stable, durable, and easy to handle. Furthermore, it is a nontoxic, nonpolluting, and low-cost material. The breast's glandular tissue (image background) was simulated by adding graphite powder with a concentration of 1% to the base material. Mixing PVCP and graphite powder in differing concentrations allows one to simulate lesions with different echogenicity patterns (anechoic, hypoechoic, and hyperechoic). From this mixture, phantom materials were obtained with speed of sound varying from 1379.3 to 1397.9ms(-1) and an attenuation coefficient having values between 0.29 and 0.94dBcm(-1) for a frequency of 1MHz at 24°C. A single layer of carnauba wax was added to the lesion surface in order to evaluate its applicability for imaging. The images of the phantoms were acquired using commercial ultrasound equipment; a specialist rated the images, elaborating diagnoses representative of both benign and malignant lesions. The results indicated that it was possible to easily create a phantom by using low-cost materials, readily available in the market and stable at room temperature, as the basis of ultrasonic phantoms that reproduce the image characteristics of fatty breast tissue and typical lesions of the breast.

  5. Synthesis and characterization of Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 nanocomposite as a polymer-inorganic hybrid catalyst for the Suzuki-Miyaura cross-coupling reaction

    SciTech Connect

    Kalbasi, Roozbeh Javad; Mosaddegh, Neda

    2011-11-15

    Composite poly(N-vinyl-2-pyrrolidone)/KIT-5 (PVP/KIT-5) was prepared by in situ polymerization method and used as a support for palladium nanoparticles obtained through the reduction of Pd(OAc){sub 2} by hydrazine hydrate. The physical and chemical properties of the catalyst were investigated by XRD, FT-IR, UV-vis, TG, BET, SEM, and TEM techniques. The catalytic performance of this novel heterogeneous catalyst was determined for the Suzuki-Miyaura cross-coupling reaction between aryl halides and phenylboronic acid in the presence of water at room temperature. The stability of the nanocomposite catalyst was excellent and could be reused 8 times without much loss of activity in the Suzuki-Miyaura cross-coupling reaction. - Graphical Abstract: Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 was prepared as an organic-inorganic hybrid catalyst for the Suzuki-Miyaura reaction. The stability of the catalyst was excellent and could be reused 8 times in the Suzuki-Miyaura reaction. Highlights: > Pd-poly(N-vinyl-2-pyrrolidone)/KIT-5 was prepared as a novel nanocomposite. > Nanocomposite was prepared based on a cage-type mesoporous system. > Catalyst showed excellent activity for Suzuki-Miyaura reaction in water. > Stability of the catalyst was excellent and could be reused 8 times.

  6. Structure of Pigment Yellow 181 dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate from XRPD + DFT-D.

    PubMed

    van de Streek, Jacco

    2015-02-01

    With only a 2.6 Å resolution laboratory powder diffraction pattern of the θ phase of Pigment Yellow 181 (P.Y. 181) available, crystal-structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom, was determined in three stages by a combination of simulated annealing, partial Rietveld refinement with dummy atoms replacing the solvent molecules and further simulated annealing. The θ phase not being of commercial interest, additional experiments were not economically feasible and additional dispersion-corrected density functional theory (DFT-D) calculations were employed to confirm the correctness of the crystal structure. After the correctness of the structure had been ascertained, the bond lengths and valence angles from the DFT-D minimized crystal structure were fed back into the Rietveld refinement as geometrical restraints (`polymorph-dependent restraints') to further improve the details of the crystal structure; the positions of the H atoms were also taken from the DFT-D calculations. The final crystal structure is a layered structure with an elaborate network of hydrogen bonds.

  7. A study of the swelling and model protein release behaviours of radiation-formed poly(N-vinyl 2-pyrrolidone-co-acrylic acid) hydrogels

    NASA Astrophysics Data System (ADS)

    Wang, David; Hill, David J. T.; Rasoul, Firas; Whittaker, Andrew K.

    2011-02-01

    Hydrogels were prepared from poly(acrylic acid-co-N-vinyl pyrrolidone), poly(AA-co-VP) and mixtures of poly(AA-co-VP) and poly(ethylene oxide), PEO, by gamma radiolysis of aqueous solutions of the AA and VP monomers containing ethylene glycol dimethacrylate, EGDMA, as crosslinker and PEO. The AA/VP composition range of the poly(AA-co-VP) was XAA 0.7-0.9. The swelling behaviours of the hydrogels from the dry state were investigated in water (pH 6.5) and 50 mM 4-(2-hydroxyethyl)piperazine-1-ethylsulfonic acid buffer, HEPES buffer, at pH 7.4 and 295 K. The effects of poly(AA-co-VP) composition, crosslinker mole fraction and the presence of PEO on the equilibrium swelling ratio for the gels was examined. The kinetics of the release of a model protein, horseradish peroxidase, HRP, from the hydrogels in water were also studied at 295 K.

  8. Zinc l-pyrrolidone carboxylate inhibits the UVA-induced production of matrix metalloproteinase-1 by in vitro cultured skin fibroblasts, whereas it enhances their collagen synthesis.

    PubMed

    Takino, Y; Okura, F; Kitazawa, M; Iwasaki, K; Tagami, H

    2012-02-01

    Reduced collagen matrix in the dermis constitutes one of the characteristic features of chronologically aged skin, which is further enhanced on the sun-exposed portions of the body by chronic ultraviolet light (UV) irradiation, inducing the unique changes associated with skin photoageing. The zinc salt of l-pyrrolidone carboxylate (Zinc PCA) has long been used as a cosmetic ingredient, because of its astringent and anti-microbial properties. In the present study, by employing cultured normal human dermal fibroblasts, we found that Zinc PCA suppressed UVA-induced activation of activator protein-1 (AP-1) and reduced matrix metalloproteinase-1 production in these cells, which is thought to be involved in collagen degradation in photoaged skin. Moreover, Zinc PCA treatment of the cells increased the expression of an ascorbic acid transporter mRNA, SVCT2, but not SVCT1, resulting in the enhanced production of type I collagen. Based on these in vitro findings, we consider Zinc PCA to be a promising candidate for an anti-skin ageing agent.

  9. Pressure-sensitive adhesive properties of poly(N-vinyl pyrrolidone)/D,L-lactic acid oligomer/glycerol/water blends for TDDS.

    PubMed

    Zhang, Jianhua; Deng, Liandong; Zhao, Hujia; Liu, Mei; Jin, Hongjian; Li, Jingqing; Dong, Anjie

    2010-01-01

    In order to develop a new type of pressure-sensitive adhesive (PSA) for a transdermal drug-delivery system (TDDS), a quaternary blend (PDGW) composed of poly(N-vinyl pyrrolidone) (PVP), D,L-lactic acid oligomer (DLLAO), glycerol and water was prepared, in which glycerol and water were used as plasticizer. The effects of the number-average molecular weight (M(n)) of DLLAO and the contents of DLLAO and plasticizer on the PSA properties were studied. The results suggest that PDGW exhibits excellent PSA properties when M(n) of DLLAO is in the range of about 200-400 and the contents of DLLAO, glycerol and water are in the range of 5-20, 15-25 and 20-35 wt%, respectively. The miscibility between PVP and DLLAO was investigated via DSC, TGA and FT-IR, and all results indicate that PVP has good miscibility with DLLAO due to strong hydrogen-bond interaction. The storage stability of PDGW also was studied and the results show that the PDGW matrix possesses stable properties over time. In addition, in vivo skin irritation of PDGW was investigated using rabbit as model animal, and the results show that the PDGW does not cause irritation to skin after topical application for 120 h. Therefore, the PDGW possesses excellent PSA properties and presents potential application in TDDS.

  10. Separation of statistical poly[(N-vinyl pyrrolidone)-co-(vinyl acetate)]s by reversed-phase gradient liquid chromatography.

    PubMed

    Cheng, Guanglou; Cullen, Jim; Wu, Chi-san

    2011-01-14

    Although size exclusion chromatography (SEC) has been used successfully to determine the molecular weight distribution (MWD) of statistical poly[(N-vinyl pyrrolidone)-co-(vinyl acetate)]s [PVPVAs], SEC cannot separate the copolymers according to their chemical composition. In this article, the separation of commercial PVPVAs with varying chemical compositions is reported, by aqueous reversed-phase gradient liquid chromatography (RPLC) using polystyrene-divinylbenzene-based wide pore columns. RPLC-SEC cross-fractionation indicates the presence of molar mass dependant effects during RPLC separation due to broad MWD for the copolymer studied; therefore the width of the RPLC peak could not be associated entirely with chemical composition distribution of the copolymer. Coupling of RPLC with online FTIR spectroscopy reveals the increase of VA content with increasing THF gradient, an indication of interaction mechanism between VA repeating units and the stationary phase for water soluble PVPVAs. Separation of water insoluble PVPVAs and PVAs by the RPLC are possibly based on both interaction and precipitation/redissolution mechanisms.

  11. Pyrolysis-gas chromatography-mass spectrometry for studying N-vinyl-2-pyrrolidone-co-vinyl acetate copolymers and their dissolution behaviour.

    PubMed

    Chojnacka, Aleksandra; Ghaffar, Abdul; Feilden, Andrew; Treacher, Kevin; Janssen, Hans-Gerd; Schoenmakers, Peter

    2011-11-14

    Knowledge on the solubility behaviour and dissolution rate of speciality and commodity polymers is very important for the use of such materials in high-tech applications. We have developed methods for the quantification and characterization of dissolved copolymers of N-vinyl-2-pyrrolidone (VP) and vinyl acetate (VA) during dissolution in water. The methods are based on pyrolysis (Py) performed in a programmed-temperature vaporization injector with subsequent identification and quantification of the components in the pyrolysate using capillary gas chromatography-mass spectrometry (GC-MS). By injecting large volumes and applying cryo-focussing at the top of the column, low detection limits could be achieved. The monomer ratio was found to have the greatest effect on the dissolution rate of the PVP-co-VA copolymers. The material with the highest amount of VA (50%) dissolves significantly slower than the other grades. Size-exclusion chromatography (SEC) and Py-GC-MS were used to measure molecular weights and average chemical compositions, respectively. Combined off-line SEC//Py-GC-MS was used to determine the copolymer composition (VP/VA ratio), as a function of the molecular weight for the pure polymers. In the dissolution experiments, a constant VP/VA ratio across the dissolution curve was observed for all copolymers analysed. This suggests a random distribution of the two monomers over the molecules.

  12. Influence of water dilution on percutaneous absorption of N-vinyl-2-pyrrolidone in vivo and ex vivo in rats and ex vivo in humans.

    PubMed

    Marquet, Fabrice; Payan, Jean-Paul; Beydon, Dominique; Wathier, Ludivine; Ferrari, Elisabeth; Grandclaude, Marie-Christine

    2015-11-01

    N-vinyl-2-pyrrolidone (NVP) is mainly used as a monomer in the production of polyvinylpyrrolidone or copolymers. Percutaneous absorption is an important source of exposure in the work environment. However, few studies have investigated this route of absorption. In this study, percutaneous absorption of neat or aqueous NVP solutions was measured in vivo and ex vivo in rats, and ex vivo in humans. Penetration and absorption fluxes were very similar following in vivo exposure to neat NVP (0.54 and 0.43 mg/cm(2)/h, respectively). Exposing rats to a 50% aqueous solution of NVP increased both fluxes threefold (to 1.48 and 1.55 mg/cm(2)/h, respectively). Ex vivo, the absorption flux increased with solutions from 10 to 25% of NVP, reached a plateau (between 25 and 50% in rat, 25 and 75% in human) and then decreased with neat NVP. In vivo and ex vivo absorption fluxes measured using rat skin were similar, supporting the hypothesis that the ex vivo measurements were a good representation of what was observed in vivo. Thus, for humans, the ex vivo measurements are likely the same as would be determined in vivo.

  13. Chronic ethanol intake modifies pyrrolidon carboxypeptidase activity in mouse frontal cortex synaptosomes under resting and K+ -stimulated conditions: role of calcium.

    PubMed

    Mayas, María Dolores; Ramírez-Expósito, María Jesús; García-López, María Jesús; Carrera, María Pilar; Martínez-Martos, José Manuel

    2008-07-04

    Pyrrolidon carboxypeptidase (Pcp) is an omega peptidase that removes pyroglutamyl N-terminal residues of peptides such as thyrotrophin-releasing hormone (TRH), which is one of the neuropeptides that has been localized into many areas of the brain and acts as an endogenous neuromodulator of several parameters related to ethanol (EtOH) consumption. In this study, we analysed the effects of chronic EtOH intake on Pcp activity on mouse frontal cortex synaptosomes and their corresponding supernatant under basal and K+ -stimulated conditions, in presence and absence of calcium (Ca2+) to know the regulation of Pcp on TRH. In basal conditions, chronic EtOH intake significantly decreased synaptosomes Pcp activity but only in absence of Ca2+. However, supernatant Pcp activity is also decreased in presence and absence of calcium. Under K+-stimulated conditions, chronic EtOH intake decreased synaptosomes Pcp activity but only in absence of Ca2+, whereas supernatant Pcp activity was significantly decreased only in presence of Ca2+. The general inhibitory effect of chronic EtOH intake on Pcp activity suggests an inhibition of TRH metabolism and an enhancement of TRH neurotransmitter/neuromodulator functions, which could be related to putative processes of tolerance to EtOH in which TRH has been involved. Our data may also indicate that active peptides and their degrading peptidases are released together to the synaptic cleft to regulate the neurotransmitter/neuromodulator functions of these peptides, through a Ca2+ -dependent mechanism.

  14. Radiation synthesized poly( n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles as LSPR-based optical sensor for mercury ions estimation

    NASA Astrophysics Data System (ADS)

    Misra, Nilanjal; Kumar, Virendra; Goel, Narender Kumar; Varshney, Lalit

    2015-07-01

    Poly( n-vinyl-2-pyrrolidone)-stabilized-gold nanoparticles (PVP-Au-NPs) have been synthesized via a green-60Co-Gamma radiolytic route and employed as a localized surface plasmon resonance (LSPR)-based optical sensor for estimation of trace quantities of Hg2+ ion in aqueous solutions. The in situ generated PVP-Au-NPs were characterized using UV-vis spectroscopy, transmission electron microscopy, and particle size analysis techniques. Reaction conditions were optimized to obtain uniformly dispersed PVP-Au-NPs with average particle size of 7.1 ± 1.6 nm (±s), which exhibited a narrow LSPR band at 527 nm. The decrease in LSPR band intensity of PVP-Au-NPs with increase in Hg2+ ion concentration was found to be linear in the Hg2+ ion concentration range of 0-100 nM. The LSPR-based PVP-Au-NPs optical sensor system was found to be selective for Hg2+ and independent of interference from other metal ions such as Ca2+, Cu2+, Cd2+, and Fe2+ up to a concentration of 500 nM.

  15. Preparing oxidized fractions of polyvinyl alcohol of a given molecular mass

    NASA Astrophysics Data System (ADS)

    Zimin, Yu. S.; Kutlugil'dina, G. G.; Mustafin, A. G.

    2016-10-01

    The effect of two oxidizers (an oxygen-ozone mixture and hydrogen peroxide) on the kinetics of the oxidative degradation of polyvinyl alcohol in aqueous solutions is studied. Degradation of the polymer is proved not only by a reduction in the weight of oxidized fractions, but in the intrinsic viscosity of their aqueous solutions as well (and thus the average molecular weight of the resulting fractions). It is shown that the degree of the destructive reactions of polyvinyl alcohol grows along with the duration of the process, increasing the initial concentrations of H2O2 and raising the temperature. These results can be used in obtaining oxidized fractions of polyvinyl alcohol that have predetermined molecular weights.

  16. [Identification of unknown substances in polyvinyl chloride gloves containing non-phthalate plasticizers].

    PubMed

    Kawamura, Yoko; Mutsuga, Motoh; Wakui, Chiseko; Maitani, Tamio

    2002-08-01

    The use of polyvinyl chloride gloves containing di(2-ethylhexyl) phthalate for food contact applications is restricted. In their place, polyvinyl chloride gloves containing non-phthalate plasticizers (PVC-NP) have been introduced. They contained unknown substances, so they were studied by GC/MS, HR-MS and NMR. The chemical structures of the unknown substances were confirmed to be diethylene glycol dibenzoate, triethylene glycol dibenzoate, dipropylene glycol dibenzoate, and alkylsulfonic acid phenyl ester, which are plasticizers. Including di-isononyl adipate, the contents of the plasticizers were 37.5-48.9% in the PVC-NP gloves, and their migration levels were 1,010-1,390 ppm into n-heptane. These are very high levels. These plasticizers are not widely used for food contact polyvinyl chloride throughout the world, and they have also not been registered as self-standards by Japanese manufacturers. Careful consideration will be necessary for the selection of a suitable plasticizer substitute.

  17. High-flow priapism treated with superselective transcatheter embolization using polyvinyl alcohol particles

    PubMed Central

    Sánchez-López, Sebastián; González-Gómez, Silvia; Di lizio-Miele, Katyna; González-Gómez, Joaquín

    2017-01-01

    Objectives: Priapism is a persistent erection of the penis not associated with sexual stimulation. High-flow priapism is caused by unregulated arterial inflow, usually preceded by perineal or penile blunt trauma and formation of an arterial-lacunar fistula. We present a case of high-flow priapism in a 13-year-old patient managed with polyvinyl alcohol particles. Methods: After obtaining informed consent of the parents of the minor, diagnosis was made with penile Color Doppler Ultrasound and confirmed with flush angiography. Selective arterial embolization was performed with the use of polyvinyl alcohol particles. Results: Complete detumescence was achieved without compromising the patient’s erectile function. Conclusions: The use of permanent occlusive agents like polyvinyl alcohol particles for embolization shows good occlusion rates compared to temporary agents. More studies are needed to find the safer and better agent for the treatment of high flow priapism without compromising erectile function. PMID:28255447

  18. Carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing.

    PubMed

    Zhang, Di; Zhou, Wei; Wei, Bing; Wang, Xin; Tang, Rupei; Nie, Jiemin; Wang, Jun

    2015-07-10

    The objective of this study was to develop a novel carboxyl-modified poly(vinyl alcohol)-crosslinked chitosan hydrogel films for potential wound dressing. To prepare the crosslinked hydrogels, poly(vinyl alcohol) (PVA) was grafted with succinate acid to yield carboxyl-modified poly(vinyl alcohol) (PVA-COOH). Hydrogel films based on PVA-COOH and chitosan (CS) at different concentrations were crosslinked through the formation of amide linkages. The mechanical properties of these crosslinked hydrogel films in dry and swollen state were greatly improved with high swelling ratio. Water vapor and oxygen permeability evaluations indicated that crosslinked hydrogel films could maintain a moist environment over wound bed. Biocompatibility test showed the crosslinked hydrogels had no cytotoxicity and hemolytic potential. Gentamicin sulfate-loaded crosslinked hydrogel films showed sustained drug release profile, and could effectively suppress bacterial proliferation and protect wound from infection.

  19. Delayed spontaneous perforation of polyvinyl alcohol membrane-Covered atrial septal defect closure devices.

    PubMed

    Labombarda, Fabien; Roule, Vincent; Beygui, Farzin

    2017-03-01

    Percutaneous device closure has become the first choice for secundum atrial septal defect (ASD) closure when feasible in case of favorable anatomy. The Ultrasept II ASD occluder® device (Cardia Inc, Eagan, MN) is made of two nitinol disc frames covered with polyvinyl alcohol membranes, a synthetic polymer with a large application in the biomedical field. Four relatively early malfunctions of the polyvinyl alcohol membrane were observed in a series of six consecutive patients treated with ASD Ultrasept II closure device in our institution. Operators have to be aware of this apparently rare complication that is likely to be underestimated, associated with such devices. © 2016 Wiley Periodicals, Inc.

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

    SciTech Connect

    Dabhi, Shweta Jha, Prafulla K.

    2014-04-24

    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.

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

    SciTech Connect

    Oji, L.N.

    1998-11-25

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

  2. Oxidative Mineralization and Characterization of Polyvinyl Alcohol Solutions for Wastewater Treatment

    SciTech Connect

    Oji, L.N.

    1999-08-31

    The principal objectives of this study are to identify an appropriate polyvinyl alcohol (PVA) oxidative mineralization technique, perform compatibility and evaporation fate tests for neat and mineralized PVA, and determine potential for PVA chemical interferences which may affect ion exchange utilization for radioactive wastewater processing in the nuclear industry.

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

    PubMed

    Meenakshi; Ahuja, Munish

    2015-01-01

    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.

  4. 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...

  5. 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...

  6. Hybrid composite based on poly(vinyl alcohol) and fillers from renewable resources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hybrid composite laminates consisting of polyvinyl alcohol (PVA) as continuous phase (33% by weight) and lignocellulosic fillers, derived from sugarcane bagasse, apple and orange waste (22% by weight) were molded in a carver press in the presence of water and glycerol such as platicizers agents. Cor...

  7. Hybrid composite based on poly(vinyl alcohol) and fillers from renewable resources

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hybrid composite laminates consisting of polyvinyl alcohol (PVA) as continuous phase and lignocellulosic fibres, derived from sugarcane bagasse, apple and orange waste were moulded in a carver press in the presence of water and glycerol such as platicizers agents. Corn starch was introduced as a bio...

  8. Films from spruce galactoglucomannan blended with poly(vinyl alcohol), corn arabinoxylan and konjac glucomannan

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The improvement of mechanical properties of spruce galactoglucomannan (GGM)-based films was sought by blending GGM with each of poly(vinyl alcohol) (PVOH), corn arabinoxylan (cAX), and konjac glucomannan (KGM). The blend ratios were 3:1, 1:1, and 1:3(w/w), and in addition films were made from each o...

  9. 76 FR 30604 - National Emission Standards for Hazardous Air Pollutants for Polyvinyl Chloride and Copolymers...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-26

    ... AGENCY 40 CFR Part 63 RIN 2060-AN33 National Emission Standards for Hazardous Air Pollutants for..., the proposed rule, National Emission Standards for Hazardous Air Pollutants for Polyvinyl Chloride and... regarding the EPA's proposed national emission standards for hazardous air pollutants, including data,...

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

    SciTech Connect

    Oji, L.N.

    2000-01-04

    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.

  11. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyvinyl chloride (PVC) is basic material for drinking water lines for chickens. Inner surface of PVC pipe can be susceptible to surface-attachment of Salmonella, the 1st stage of biofilm development. Biofilm which can cause Salmonella infection to chickens are known to have great resistance agains...

  13. Preparation of albumin preferential surfaces on poly(vinyl chloride) membranes via surface self-segregation.

    PubMed

    Ji, Jian; Feng, Linxian; Shen, Jiacong; Barbosa, M A

    2002-08-01

    Poly(vinyl chlorides)-graft-[omega-stearyl-poly(ethylene oxide)] (PVC-g-SPEO), which has a poly(vinyl chloride) (PVC) backbone, poly(ethylene oxide) (PEO) side chain, and stearyl end groups, has been synthesized. Self-organizing blends of the amphiphilic comb polymer in poly(vinyl chlorides) have been examined as a means to create albumin preferential surfaces on polymer films. X-ray photoelectron spectroscopy (XPS) analysis indicates substantial surface segregation of the PVC-g-SPEO. A surface concentration of 59.9 EO wt % is achieved by the solution casting and heat treatment of a film with a bulk concentration of only 3.78 EO wt %. In the aqueous environment, the surface rearrangement of PVC-g-SPEO/PVC blend film is limited and presents a high interfacial energy and high depolar component of interfacial energy due to the "tail-like" SPEO side chain. Protein adsorption tests confirm that PVC-g-SPEO/PVC blend films absorb high levels of albumin and dramatically resist fibrinogen adsorption. Surfaces to attract and reversibly bind albumin, which might diminish the occurrence of thrombosis, inflammation, and infection, are developed by self-organizing blends of the amphiphilic comb polymer in poly(vinyl chlorides).

  14. Effect of processing temperature on the properties of a polyvinyl chloride maxillofacial elastomer.

    PubMed

    Yu, R; Koran, A; Powers, J M

    1983-10-01

    Mechanical properties and color of a plasticized polyvinyl chloride (PVC) maxillofacial elastomer were evaluated at processing temperatures from 140 to 190 degrees C. The properties were dependent on processing temperature. Specimens prepared at 170 degrees C had optimum mechanical properties with minimal discoloration.

  15. Neutron attenuation characteristics of polyethylene, polyvinyl chloride, and heavy aggregate concrete and mortars.

    PubMed

    Abdul-Majid, S; Othman, F

    1994-03-01

    Polyethylene and polyvinyl chloride pellets were introduced into concrete to improve its neutron attenuation characteristics while several types of heavy coarse aggregates were used to improve its gamma ray attenuation properties. Neutron and gamma ray attenuation were studied in concrete samples containing coarse aggregates of barite, pyrite, basalt, hematite, and marble as well as polyethylene and polyvinyl chloride pellets in narrow-beam geometry. The highest neutron attenuation was shown by polyethylene mortar, followed by polyvinyl chloride mortar; barite and pyrite concrete showed higher gamma ray attenuation than ordinary concrete. Broad-beam and continuous (infinite) medium geometries were used to study the neutron attenuation of samples containing polymers at different concentrations with and without heavy aggregates, the fitting equations were established, and from these the neutron removal coefficients were deduced. In a radiation field of neutrons and gamma rays, the appropriate concentration of polymer and heavy aggregate can be selected to give the optimum total dose attenuation depending on the relative intensities of each type of radiation. This would give much better design flexibility over ordinary concrete. The compressive strength tests performed on mortar and concrete samples showed that their value, in general, decreases as polymer concentration increases and that the polyvinyl chloride mortar showed higher values than the polyethylene mortar. For general construction purposes, the compression strength was considered acceptable in these samples.

  16. Mechanical properties and biocompatibility of co-axially electrospun polyvinyl alcohol/maghemite.

    PubMed

    Ngadiman, Nor Hasrul Akhmal; Mohd Yusof, Noordin; Idris, Ani; Kurniawan, Denni

    2016-08-01

    Electrospinning is a simple and efficient process in producing nanofibers. To fabricate nanofibers made of a blend of two constituent materials, co-axial electrospinning method is an option. In this method, the constituent materials contained in separate barrels are simultaneously injected using two syringe nozzles arranged co-axially and the materials mix during the spraying process forming core and shell of the nanofibers. In this study, co-axial electrospinning method is used to fabricate nanofibers made of polyvinyl alcohol and maghemite (γ-Fe2O3). The concentration of polyvinyl alcohol and amount of maghemite nanoparticle loading were varied, at 5 and 10 w/v% and at 1-10 v/v%, respectively. The mechanical properties (strength and Young's modulus), porosity, and biocompatibility properties (contact angle and cell viability) of the electrospun mats were evaluated, with the same mats fabricated by regular single-nozzle electrospinning method as the control. The co-axial electrospinning method is able to fabricate the expected polyvinyl alcohol/maghemite nanofiber mats. It was noticed that the polyvinyl alcohol/maghemite electrospun mats have lower mechanical properties (i.e. strength and stiffness) and porosity, more hydrophilicity (i.e. lower contact angle), and similar cell viability compared to the mats fabricated by single-nozzle electrospinning method.

  17. Magnetic Properties of Polyvinyl Alcohol and Doxorubicine Loaded Iron Oxide Nanoparticles for Anticancer Drug Delivery Applications

    PubMed Central

    Nadeem, Muhammad; Ahmad, Munir; Akhtar, Muhammad Saeed; Shaari, Amiruddin; Riaz, Saira; Naseem, Shahzad; Masood, Misbah; Saeed, M. A.

    2016-01-01

    The current study emphasizes the synthesis of iron oxide nanoparticles (IONPs) and impact of hydrophilic polymer polyvinyl alcohol (PVA) coating concentration as well as anticancer drug doxorubicin (DOX) loading on saturation magnetization for target drug delivery applications. Iron oxide nanoparticles particles were synthesized by a reformed version of the co-precipitation method. The coating of polyvinyl alcohol along with doxorubicin loading was carried out by the physical immobilization method. X-ray diffraction confirmed the magnetite (Fe3O4) structure of particles that remained unchanged before and after polyvinyl alcohol coating and drug loading. Microstructure and morphological analysis was carried out by transmission electron microscopy revealing the formation of nanoparticles with an average size of 10 nm with slight variation after coating and drug loading. Transmission electron microscopy, energy dispersive, and Fourier transform infrared spectra further confirmed the conjugation of polymer and doxorubicin with iron oxide nanoparticles. The room temperature superparamagnetic behavior of polymer-coated and drug-loaded magnetite nanoparticles were studied by vibrating sample magnetometer. The variation in saturation magnetization after coating evaluated that a sufficient amount of polyvinyl alcohol would be 3 wt. % regarding the externally controlled movement of IONPs in blood under the influence of applied magnetic field for in-vivo target drug delivery. PMID:27348436

  18. [Preparation and clinical application of polyvinyl alcohol/drug-loaded chitosan microsphere composite wound dressing].

    PubMed

    Zhang, Xiuju; Lin, Zhidan; Chen, Wenbin; Song, Ying; Li, Zhizhong

    2011-04-01

    In order to prepare and apply the polyvinyl alcohol/drug-loaded chitosan microspheres composite wound dressing, we first prepared chitosan microspheres by emulsion cross-linking method, and then added chitosan microspheres into the reactants during the acetalization of polyvinyl alcohol and formaldehyde. We further studied the morphology, water absorption, swelling degree, mechanical properties and in vitro release of the sponge with different amount of chitosan microspheres. The results showed that polyvinyl alcohol/drug-loaded chitosan composite sponge has porous structure with connectionism. Increasing the amount of chitosan microspheres would make the apertures smaller, so that the water absorption and the swelling of sponge decreased, but the tensile strength and compressive strength increased. With the increase of the amount of chitosan microspheres, the drug absorption of cefradine and the release rate increase, and the release time become longer. With the results of toxicity grade of 0 to 1, this type of composite sponge is non-toxic and meets the requirement of biocompatibility. The observation of rabbit nasal cavity after surgical operation suggested that polyvinyl acetal sponge modified with the chitosan has antiphlogistic, hemostatic and non-adherent characteristic, and can promote the healing and recovering of the nasalmucosa. After using this composite material, best growing surroundings for patients' granulation tissue were provided. Exposed bone and tendon were covered well with granulation tissue.

  19. Controlling the color of Lippmann holograms recorded in dichromated gelatin polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Cai, Tiequan; Tang, Yixing; Wang, Hui; Dai, Chaoming; Guo, Lurong

    1993-03-01

    The polyvinyl alcohol and several other organic materials are mixed into the aqueous gelatin while the film is coated. This thin solid film is sensitized by aqueous ammonium dichromate, so it is called a dichromated gelatin polyvinyl alcohol (DC-GPVA) holographic recording material. DC-GPVA not only possesses the same excellent holographic properties as the conventional dichromated gelatin (DCG) but also obviously improves its environmental stability. Experimental results have shown that the reconstruction wavelength of a Lippman hologram recorded in DC-GPVA can be shifted to longer or shorter wavelengths and freely controlled to a certain extent by varying the ratio of the gelatin and the polyvinyl alcohol and relative organic materials, or hardeners and its quantity, or heated temperature and heated time exerted on the drying films, or thickness of them. After the films are sensitized, they can be exposed by He-Cd or Ar+ laser (441.6 nm or 488.0 nm) and developed by the regular post processed method. Initial discussions are also presented about the functions and mechanisms of the polyvinyl alcohol and relative organic materials added into DC-GPVA.

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

    ERIC Educational Resources Information Center

    Natarajan, L. V.; And Others

    1983-01-01

    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)

  1. The Rheological Properties of Poly(Vinyl Alcohol) Gels from Rotational Viscometry

    ERIC Educational Resources Information Center

    Hurst, Glenn A.; Bella, Malika; Salzmann, Christoph G.

    2015-01-01

    A laboratory experiment was developed to follow the gelation of a polyvinyl alcohol (PVA) solution upon addition of borax by using rotational viscometry. The rheological properties of the gel were examined, measuring the dependence of viscosity and shear stress on the shear rate. Time-dependent studies were also conducted in which the viscosity of…

  2. Effects of N-methyl pyrrolidone on the uptake of hypericin in human bladder carcinoma and co-staining with DAPI investigated by confocal microscopy.

    PubMed

    Saw, Constance Lay Lay; Olivo, Malini; Wohland, Thorsten; Fu, Chit Yaw; Kho, Kiang Wei; Soo, Khee Chee; Sia Heng, Paul Wan

    2007-10-01

    Photodynamic diagnosis (PDD) using hypericin (HY), a natural photosensitizer, detects bladder cancer significantly better than white light endoscopy. However, the lipophilicity of HY complicates its administration for clinical applications. Currently, pharmaceutical preparations for HY without plasma protein are being developed. Formulations containing a biocompatible solvent, N-methyl pyrrolidone (NMP) have been shown to enhance the photodynamic therapeutic effects of HY. It was recently reported that, NMP formulations of HY were able to produce significantly higher contrast for fluorescence detection of tumors than albumin-containing HY formulations. This present work hypothesizes that NMP acts both as a solvent and penetration enhancer to improve the delivery of HY into cells by increasing the permeability of cell membranes. This paper reports the use of 3-D confocal microscopy to monitor real-time uptake of HY in human carcinoma. 3-D confocal microscopy was used to investigate the possibility of nuclear localization of HY in MGH cells. The fluorescence of HY was confirmed to be emitted from HY containing cells using spectrometry. The localization of a DNA fluorescent probe 4', 6-diamidino-2-phenylindole dihydrochloride (DAPI) was used to confirm the possibility of colocalization of DAPI and HY. The colocalization analysis in the present study suggests that it was very unlikely that HY colocalized in the nucleus that was stained by DAPI. Fluorescein leakage tests showed that 1% NMP changes the permeability of cell membranes, and enhanced the delivery of HY into cells resulting in lower cell survival ratios. Thus, NMP was able to enhance the photodynamic therapeutic effects of HY on cancer cells.

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

    SciTech Connect

    Not Available

    1992-01-01

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

  4. RAFT Aqueous Dispersion Polymerization of N-(2-(Methacryloyloxy)ethyl)pyrrolidone: A Convenient Low Viscosity Route to High Molecular Weight Water-Soluble Copolymers.

    PubMed

    Cunningham, Victoria J; Derry, Matthew J; Fielding, Lee A; Musa, Osama M; Armes, Steven P

    2016-06-28

    RAFT solution polymerization of N-(2-(methacryoyloxy)ethyl)pyrrolidone (NMEP) in ethanol at 70 °C was conducted to produce a series of PNMEP homopolymers with mean degrees of polymerization (DP) varying from 31 to 467. Turbidimetry was used to assess their inverse temperature solubility behavior in dilute aqueous solution, with an LCST of approximately 55 °C being observed in the high molecular weight limit. Then a poly(glycerol monomethacylate) (PGMA) macro-CTA with a mean DP of 63 was chain-extended with NMEP using a RAFT aqueous dispersion polymerization formulation at 70 °C. The target PNMEP DP was systematically varied from 100 up to 6000 to generate a series of PGMA63-PNMEP x diblock copolymers. High conversions (≥92%) could be achieved when targeting up to x = 5000. GPC analysis confirmed high blocking efficiencies and a linear evolution in Mn with increasing PNMEP DP. A gradual increase in Mw/Mn was also observed when targeting higher DPs. However, this problem could be minimized (Mw/Mn < 1.50) by utilizing a higher purity grade of NMEP (98% vs 96%). This suggests that the broader molecular weight distributions observed at higher DPs are simply the result of a dimethacrylate impurity causing light branching, rather than an intrinsic side reaction such as chain transfer to polymer. Kinetic studies confirmed that the RAFT aqueous dispersion polymerization of NMEP was approximately four times faster than the RAFT solution polymerization of NMEP in ethanol when targeting the same DP in each case. This is perhaps surprising because both (1)H NMR and SAXS studies indicate that the core-forming PNMEP chains remain relatively solvated at 70 °C in the latter formulation. Moreover, dissolution of the initial PGMA63-PNMEP x particles occurs on cooling from 70 to 20 °C as the PNMEP block passes through its LCST. Hence this RAFT aqueous dispersion polymerization formulation offers an efficient route to a high molecular weight water-soluble polymer in a rather

  5. RAFT Aqueous Dispersion Polymerization of N-(2-(Methacryloyloxy)ethyl)pyrrolidone: A Convenient Low Viscosity Route to High Molecular Weight Water-Soluble Copolymers

    PubMed Central

    2016-01-01

    RAFT solution polymerization of N-(2-(methacryoyloxy)ethyl)pyrrolidone (NMEP) in ethanol at 70 °C was conducted to produce a series of PNMEP homopolymers with mean degrees of polymerization (DP) varying from 31 to 467. Turbidimetry was used to assess their inverse temperature solubility behavior in dilute aqueous solution, with an LCST of approximately 55 °C being observed in the high molecular weight limit. Then a poly(glycerol monomethacylate) (PGMA) macro-CTA with a mean DP of 63 was chain-extended with NMEP using a RAFT aqueous dispersion polymerization formulation at 70 °C. The target PNMEP DP was systematically varied from 100 up to 6000 to generate a series of PGMA63–PNMEPx diblock copolymers. High conversions (≥92%) could be achieved when targeting up to x = 5000. GPC analysis confirmed high blocking efficiencies and a linear evolution in Mn with increasing PNMEP DP. A gradual increase in Mw/Mn was also observed when targeting higher DPs. However, this problem could be minimized (Mw/Mn < 1.50) by utilizing a higher purity grade of NMEP (98% vs 96%). This suggests that the broader molecular weight distributions observed at higher DPs are simply the result of a dimethacrylate impurity causing light branching, rather than an intrinsic side reaction such as chain transfer to polymer. Kinetic studies confirmed that the RAFT aqueous dispersion polymerization of NMEP was approximately four times faster than the RAFT solution polymerization of NMEP in ethanol when targeting the same DP in each case. This is perhaps surprising because both 1H NMR and SAXS studies indicate that the core-forming PNMEP chains remain relatively solvated at 70 °C in the latter formulation. Moreover, dissolution of the initial PGMA63–PNMEPx particles occurs on cooling from 70 to 20 °C as the PNMEP block passes through its LCST. Hence this RAFT aqueous dispersion polymerization formulation offers an efficient route to a high molecular weight water-soluble polymer in a rather

  6. Synthesis and characterization of polyvinyl alcohol based multiwalled carbon nanotube nanocomposites

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    SciTech Connect

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

    1986-11-01

    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.

  8. Reversible energy transfer between monomers and fluorescent dimers of rhodamine S in polyvinyl alcohol films

    NASA Astrophysics Data System (ADS)

    Synak, A.; Kułak, L.; Rangełowa-Jankowska, S.; Grobelna, B.; Kubicki, A.; Bojarski, P.

    2011-04-01

    Nonradiative energy transfer and excitation trapping are studied for rhodamine S in polyvinyl alcohol (PVA) films. It occurs that fluorescent dimers of rhodamine S can play a role of imperfect traps for the excitation energy. At highest dye concentrations experimental data of fluorescence quantum yield and emission anisotropy cannot be described by the model of energy transfer neglecting the possibility of excitation return to the monomers. However, the agreement between experimental data and the results of computations can be much improved, if the reverse energy transfer is taken into account. Based on the quantitative analysis it is possible to estimate selected characteristics of rhodamine S dimer in polyvinyl alcohol matrix. The experiments and corresponding analysis are made both at room and elevated temperature.

  9. Poly(vinyl alcohol)/poly(vinyl chloride) composite polymer membranes for secondary zinc electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Yang, Jen Ming; Wu, Cheng-Yeou

    A microporous composite polymer membrane composed of poly(vinyl alcohol) (PVA) and poly(vinyl chloride) (PVC), was prepared by a solution casting method and a partial dissolution process. The characteristic properties of microporous PVA/PVC composite polymer membranes containing 2.5-10 wt.% PVC polymers as fillers were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), capillary flow porometry (CFP), micro-Raman spectroscopy, dynamic mechanical analyzer (DMA) and the AC impedance method. The electrochemical properties of a secondary Zn electrode with the PVA/PVC composite polymer membrane were studied using the galvanostatic charge/discharge method. The PVA/PVC composite polymer membrane showed good thermal, mechanical and electrochemical properties. As a result, the PVA/PVC composite polymer membrane appears to be a good candidate for use on the secondary Zn electrodes.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    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.

  11. Biomaterial properties evaluation of poly(vinyl acetate- alt-maleic anhydride)/chitosan nanocapsules

    NASA Astrophysics Data System (ADS)

    Raţă, Delia Mihaela; Popa, Marcel; Chailan, Jean-François; Zamfir, Carmen Lăcrămioara; Peptu, Cătălina Anişoara

    2014-08-01

    Nanocapsules with diameter around 100 nm based on a natural polymer (chitosan) and a synthetic polymer poly(vinyl acetate- alt-maleic anhydride) [poly(MAVA)] by interfacial condensation method were prepared. The present study proposes a new type of biocompatible nanocapsules based on poly(vinyl acetate- alt-maleic anhydride-chitosan) (MCS) able to become a reliable support for inclusion and release of drugs. The spherical shape of the nanocapsules was evidenced by scanning electron microscopy. Nanocapsules presented a good Norfloxacin loading and release capacity. Haemocompatibility tests have demonstrated that the nanocapsules present a low toxicity and a good compatibility with sanguine medium. The biocompatibility properties of the nanocapsules after their intraperitoneal administration in rats were evidenced by histopathological examination of different organs (brain, liver, kidney, and lung). The results are encouraging and the nanocapsules can be used as controlled drug delivery systems.

  12. Solvent effects on the formation of nanoparticles and multilayered coatings based on hydrogen-bonded interpolymer complexes of poly(acrylic acid) with homo- and copolymers of N-vinyl pyrrolidone.

    PubMed

    Zhunuspayev, Daulet E; Mun, Grigoriy A; Hole, Patrick; Khutoryanskiy, Vitaliy V

    2008-12-02

    The formation of hydrogen-bonded interpolymer complexes between poly(acrylic acid) and poly(N-vinyl pyrrolidone) as well as amphiphilic copolymers of N-vinyl pyrrolidone with vinyl propyl ether has been studied in aqueous and organic solutions. It was demonstrated that introduction of vinyl propyl ether units into the macromolecules of the nonionic polymer enhances their ability to form complexes in aqueous solutions due to more significant contribution of hydrophobic effects. The complexation was found to be a multistage process that involves the formation of primary polycomplex particles, which further aggregate to form spherical nanoparticles. Depending on the environmental factors (pH, solvent nature), these nanoparticles may either form stable colloidal solutions or undergo further aggregation, resulting in precipitation of interpolymer complexes. In organic solvents, the intensity of complex formation increases in the following order: methanol < ethanol < isopropanol < dioxane. The multilayered coatings were developed using layer-by-layer deposition of interpolymer complexes on glass surfaces. It was demonstrated that the solvent nature affects the efficiency of coating deposition.

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

    SciTech Connect

    1995-12-01

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

  14. Polyvinyl butyral films containing leuco-malachite green as low-dose dosimeters

    NASA Astrophysics Data System (ADS)

    Mai, Hoang Hoa; Solomon, H. M.; Taguchi, M.; Kojima, T.

    2008-04-01

    Thin films containing leuco-malachite green (LMG) dye in polyvinyl butyral (PVB) have been developed for dose measurements of a few hundreds Gy level. The film shows significant color change in the visible range, and the sensitivity of the film to absorbed dose was enhanced by addition of chloride-containing compounds, such as chloral hydrate or 2,2,2-trichloroethanol. The film is suitable as dosimeters for dose measurements, e.g. in food irradiation and environmental protection.

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

    SciTech Connect

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

    1987-09-01

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

  16. Improved adhesive strength and toughness of polyvinyl acetate glue on addition of small quantities of graphene.

    PubMed

    Khan, Umar; May, Peter; Porwal, Harshit; Nawaz, Khalid; Coleman, Jonathan N

    2013-02-01

    We have prepared composites of polyvinyl acetate (PVAc) reinforced with solution exfoliated graphene. We observe a 50% increase in stiffness and a 100% increase in tensile strength on addition of 0.1 vol % graphene compared to the pristine polymer. As PVAc is commonly used commercially as a glue, we have tested such composites as adhesives. The adhesive strength and toughness of the composites were up to 4 and 7 times higher, respectively, than the pristine polymer.

  17. An outbreak of acneiform eruption in a polyvinyl chloride manufacturing factory.

    PubMed

    Goh, C L; Ho, S F

    1988-01-01

    An outbreak of acneiform eruptions occurred in 14 workers in a polyvinyl chloride (PVC) manufacturing factory. The cause was probably a combination of heat, high humidity and irritation from PVC powder. PVC slurry, scales and powder, to which the workers were exposed, were not comedogenic on rabbit ear. Lowering the temperature and humidity by airconditioning and improving ventilation, together with reduction of dust level at the workplaces, eliminated further outbreak's.

  18. Edge-enhanced imaging with polyvinyl alcohol/acrylamide photopolymer gratings.

    PubMed

    Márquez, Andrés; Neipp, Cristian; Beléndez, Augusto; Gallego, Sergi; Ortuño, Manuel; Pascual, Inmaculada

    2003-09-01

    We demonstrate edge-enhanced imaging produced by volume phase gratings recorded on a polyvinyl alcohol/acrylamide photopolymer. Bragg diffraction, exhibited by volume gratings, modifies the impulse response of the imaging system, facilitating spatial filtering operations with no need for a physical Fourier plane. We demonstrate that Kogelnik's coupled-wave theory can be used to calculate the transfer function for the transmitted and the diffracted orders. The experimental and simulated results agree, and they demonstrate the feasibility of our proposal.

  19. Evaluation of CO2-philicity of poly(vinyl acetate) and poly(vinyl acetate-alt-maleate) copolymers through molecular modeling and dissolution behavior measurement.

    PubMed

    Hu, Dongdong; Sun, Shaojun; Yuan, Peiqing; Zhao, Ling; Liu, Tao

    2015-02-19

    Multiscale molecular modeling and dissolution behavior measurement were both used to evaluate the factors conclusive on the CO2-philicity of poly(vinyl acetate) (PVAc) homopolymer and poly(vinyl acetate-alt-maleate) copolymers. The ab initio calculated interaction energies of the candidate CO2-philic molecule models with CO2, including vinyl acetate dimer (VAc), dimethyl maleate (DMM), diethyl maleate (DEM), and dibutyl maleate (DBM), showed that VAc was the most CO2-philc segment. However, the cohesive energy density, solubility parameter, Flory-Huggins parameter, and radial distribution functions calculated by using the molecular dynamics simulations for the four polymer and polymer-CO2 systems indicated that poly(VAc-alt-DBM) had the most CO2-philicity. The corresponding polymers were synthesized by using free radical polymerization. The measurement of cloud point pressures of the four polymers in CO2 also demonstrated that poly(VAc-alt-DBM) had the most CO2-philicity. Although copolymerization of maleate, such as DEM or DBM, with PVAc reduced the polymer-CO2 interactions, the weakened polymer-polymer interaction increased the CO2-philicity of the copolymers. The polymer-polymer interaction had a significant influence on the CO2-philicity of the polymer. Reduction of the polymer-polymer interaction might be a promising strategy to prepare the high CO2-philic polymers on the premise that the strong polymer-CO2 interaction could be maintained.

  20. Stability of Alprostadil in 0.9% Sodium Chloride Stored in Polyvinyl Chloride Containers.

    PubMed

    McCluskey, Susan V; Kirkham, Kylian; Munson, Jessica M

    2017-01-01

    The stability of alprostadil diluted in 0.9% sodium chloride stored in polyvinyl chloride (VIAFLEX) containers at refrigerated temperature, protected from light, is reported. Five solutions of alprostadil 11 mcg/mL were prepared in 250 mL 0.9% sodium chloride polyvinyl chloride (PL146) containers. The final concentration of alcohol was 2%. Samples were stored under refrigeration (2°C to 8°C) with protection from light. Two containers were submitted for potency testing and analyzed in duplicate with the stability-indicating high-performance liquid chromatography assay at specific time points over 14 days. Three containers were submitted for pH and visual testing at specific time points over 14 days. Stability was defined as retention of 90% to 110% of initial alprostadil concentration, with maintenance of the original clear, colorless, and visually particulate-free solution. Study results reported retention of 90% to 110% initial alprostadil concentration at all time points through day 10. One sample exceeded 110% potency at day 14. pH values did not change appreciably over the 14 days. There were no color changes or particle formation detected in the solutions over the study period. This study concluded that during refrigerated, light-protected storage in polyvinyl chloride (VIAFLEX) containers, a commercial alcohol-containing alprostadil formulation diluted to 11 mcg/mL with 0.9% sodium chloride 250 mL was stable for 10 days.

  1. Effect of polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer on bioadhesion and release rate property of eplerenone pellets.

    PubMed

    Kendre, Prakash Namdeo; Chaudhari, Pravin Digambar

    2017-05-01

    The present study involved the design and development of oral bioadhesive pellets of eplerenone. A solid dispersion of eplerenone was developed with a hydrophilic carrier, polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus(®)). Bioadhesive pellets were prepared from this solid dispersion using a combination of HPMC K4M and Carbopol 934P. Both the solid dispersion and the pellets were evaluated for various physicochemical properties such as solubility, entrapment efficiency, drug content, surface morphology, mucoadhesion and swelling behavior. Analysis carried out using FT-IR, DSC and XRD found no interaction between the eplerenone and excipients. The solid dispersion had irregular-shaped smooth-surfaced particles of diameter 265 ± 105.5 μm. In TEM analysis, eplerenone particles of size 79-120 nm were found. The solubility and dissolution of eplerenone in the Soluplus(®)-based solid dispersion were 5.26 and 2.50 times greater, respectively. Investigation of the swelling behavior of the pellets showed that the thickness of the gel layer increased continuously over the duration of the study. Moreover, a correlation was observed between the thickness and strength of the gel layer and the percentage release. The mechanism of drug release was found to be non-Fickian (anomalous), with the release kinetics approaching first-order kinetics. The bioavailability of the eplerenone bioadhesive pellet formulation was studied using Wistar rats and was found to be improved. An in vivo mucoadhesion study showed that the pellets are retained for 24 h in rabbits. It was concluded that Soluplus(®) had a positive effect on the solubility and dissolution of pellets without affecting the bioadhesion.

  2. Uranium Adsorbent Fibers Prepared by Atom-Transfer Radical Polymerization (ATRP) from Poly(vinyl chloride)- co -chlorinated Poly(vinyl chloride) (PVC- co -CPVC) Fiber

    DOE PAGES

    Brown, Suree; Yue, Yanfeng; Kuo, Li-Jung; ...

    2016-03-11

    The need to secure future supplies of energy attracts researchers in several countries to a vast resource of nuclear energy fuel: uranium in seawater (estimated at 4.5 billion tons in seawater). In this study, we developed effective adsorbent fibers for the recovery of uranium from seawater via atom-transfer radical polymerization (ATRP) from a poly-(vinyl chloride)-co-chlorinated poly(vinyl chloride) (PVC-co-CPVC) fiber. ATRP was employed in the surface graft polymerization of acrylonitrile (AN) and tert-butyl acrylate (tBA), precursors for uranium-interacting functional groups, from PVC-co-CPVC fiber. The [tBA]/[AN] was systematically varied to identify the optimal ratio between hydrophilic groups (from tBA) and uranyl-binding ligandsmore » (from AN). The best performing adsorbent fiber, the one with the optimal [tBA]/[AN] ratio and a high degree of grafting (1390%), demonstrated uranium adsorption capacities that are significantly greater than those of the Japan Atomic Energy Agency (JAEA) reference fiber in natural seawater tests (2.42 3.24 g/kg in 42 days of seawater exposure and 5.22 g/kg in 49 days of seawater exposure, versus 1.66 g/kg in 42 days of seawater exposure and 1.71 g/kg in 49 days of seawater exposure for JAEA). Lastly, adsorption of other metal ions from seawater and their corresponding kinetics were also studied. The grafting of alternative monomers for the recovery of uranium from seawater is now under development by this versatile technique of ATRP.« less

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

    PubMed

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

    2013-08-01

    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.

  4. Toxicity of the pyrolysis and combustion products of poly(vinyl chlorides): a literature assessment

    SciTech Connect

    Huggett, C.; Levin, B.C.

    1986-04-01

    Poly(vinyl chlorides) (PVC) constitute a major class of synthetic plastics. Many surveys of the voluminous literature have been performed. The report reviews the literature published in English from 1969 through 1984 and endeavors to be more interpretive than comprehensive. PVC compounds, in general, are among the more fire-resistant common organic polymers, natural or synthetic. The major products of thermal decomposition include hydrogen chloride, benzene, and unsaturated hydrocarbons. In the presence of oxygen, carbon monoxide, carbon dioxide and water are included among the common combustion products. The main toxic products from PVC fires are hydrogen chloride (a sensory and pulmonary irritant) and carbon monoxide (an asphyxiant).

  5. Electrospun nano-fibre mats with antibacterial properties from quaternised chitosan and poly(vinyl alcohol).

    PubMed

    Ignatova, Milena; Starbova, Kirilka; Markova, Nadya; Manolova, Nevena; Rashkov, Iliya

    2006-09-04

    Nano-fibres containing quaternised chitosan (QCh) have been successfully prepared by electrospinning of QCh solutions mixed with poly(vinyl alcohol) (PVA). The average fibre diameter is in the range of 60-200 nm. UV irradiation of the composite electrospun nano-fibrous mats containing triethylene glycol diacrylate as cross-linking agent has resulted in stabilising of the nano-fibres against disintegration in water or water vapours. Microbiological screening has demonstrated the antibacterial activity of the photo-cross-linked electrospun mats against Staphylococcus aureus and Escherichia coli. The obtained nano-fibrous electrospun mats are promising for wound-healing applications.

  6. Polyvinyl alcohol-cellulose nanofibrils-graphene oxide hybrid organic aerogels.

    PubMed

    Javadi, Alireza; Zheng, Qifeng; Payen, Francois; Javadi, Abdolreza; Altin, Yasin; Cai, Zhiyong; Sabo, Ronald; Gong, Shaoqin

    2013-07-10

    Hybrid organic aerogels consisting of polyvinyl alcohol (PVA), cellulose nanofibrils (CNFs), and graphene oxide nanosheets (GONSs) were prepared using an environmentally friendly freeze-drying process. The material properties of these fabricated aerogels were measured and analyzed using various characterization techniques including compression testing, scanning electron microscopy, thermogravimetric (TGA) analysis, Brunauer-Emmet-Teller (BET) surface area analysis, and contact angle measurements. These environmentally friendly, biobased hybrid organic aerogels exhibited a series of desirable properties including a high specific compressive strength and compressive failure strain, ultralow density and thermal conductivity, good thermal stability, and moisture resistance, making them potentially useful for a broad range of applications including thermal insulation.

  7. Suppression of instability by double ablation in tungsten doped polyvinyl alcohol foils

    NASA Astrophysics Data System (ADS)

    Peedikakkandy, Leshma; Chaurasia, S.

    2012-07-01

    In Inertial fusion Energy (IFE) research stable acceleration of fusion targets is a significant problem due to hydrodynamic instabilities. This paper presents the results of the experiments done to investigate the effects of doping 20% of Tungsten (W) (by weight) in Polyvinyl Alcohol (PVA) polymer foils for suppression of instability during laser ablative acceleration. A 20J, 1.060μm, 900ps, Nd: Glass laser system with a focusable intensity of 3 to 9.6×1013W/cm2 was used in the experiment. It is observed that the doped PVA targets yielded stable and enhanced foil acceleration as compared to the undoped PVA foils.

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

    PubMed Central

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

    2012-01-01

    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

  9. Preparation and Characterization of Palm Leaf Incorporated Polyvinyl Alcohol Bio Composites

    NASA Astrophysics Data System (ADS)

    Patel, Arunendra Kumar; Bajpai, Rakesh; Keller, J. M.; Saha, Abhijit

    2011-12-01

    The Bio Composites of palm leaf (PL) incorporated polyvinyl alcohol (PVA) has been prepared using solution cast technique. Structural and microhardness properties of pure PVA and PL filled PVA Bio Composites has been determined by using FTIR and Vicker's indentation techniquque respectively. The FTIR analysis reveals the presence of PL moieties in PVA, which indicates the good compatibility between PL and PVA. The values of microhardness increases in all composition of PL incorporated PVA films as compared to the pure PVA. This increment in the microhardness is attributed to the excellent binding of PL into PVA.

  10. Coimmobilization of urease and glutamate dehydrogenase in electrochemically prepared polypyrrole-polyvinyl sulfonate films.

    PubMed

    Gambhir, A; Gerard, M; Mulchandani, A K; Malhotra, B D

    2001-01-01

    Immobilization of urease and glutamate dehydrogenase enzymes in electrochemically prepared polypyrrole-polyvinyl sulfonate films (PPY-PVS) was carried out using physical adsorption and electrochemical entrapment techniques. Detailed studies on optimum pH, Fourier transform infrared spectroscopy, cyclic voltammetry, and scanning electron microscopy of the enzymes in the immobilized state were conducted. The value of the apparent Michaelis-Menten constant was experimentally determined to be 2.5 and 2.7 for physically adsorbed and electrochemically entrapped urease in PPY-PVS films, respectively.

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

    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.

  12. Impact behaviour of an innovative plasticized poly(vinyl chloride) for the automotive industry

    NASA Astrophysics Data System (ADS)

    Bernard, C. A.; Bahlouli, N.; Wagner-Kocher, C.; Ahzi, S.; Rémond, Y.

    2015-09-01

    Plasticized poly(vinyl chloride) (PPVC) is widely used in the automotive industry in the design of structural parts for crashworthiness applications. Thus, it is necessary to study and understand the influence of the mechanical response and mechanical properties of PPVC over a wide range of strain rate, from quasi-static to dynamic loadings. The process is also investigated using different sample thicknesses. In this work, the strain rate effect of a new PPVC is investigated over a wide range of strain rates at three temperatures and for three thicknesses. A modelling of the yield stress is also proposed. The numerical prediction is in good agreement with the experimental results.

  13. Incorporation of a vacuum-formed polyvinyl chloride sheet into an orbital prosthesis pattern.

    PubMed

    Kumar, Pradeep; Singh, Saumyendra Vikram; Aggarwal, Himanshi; Chand, Pooran

    2015-02-01

    Pattern formation is the most difficult and demanding step in the fabrication of a facial prosthesis. Traditionally, the pattern fabrication of an orbital prosthesis begins with the adaptation of softened base plate wax on the cast, over which the entire pattern is fabricated. However, owing to the inherent properties of wax, such as distortion and stress relaxation, incorporating discrepancies in the pattern adaptation is likely. This article describes a vacuum-formed polyvinyl chloride sheet to fabricate a durable, distortion-free base for pattern fabrication, thereby overcoming the drawbacks associated with a wax base.

  14. [Risk assessment of health disorders and quality of life in employees of modern polyvinyl chloride production].

    PubMed

    Meshchakova, N M; D'iakovich, M P; Shaiakhmetov, S F; D'iakovich, O A; Telezhkin, V V

    2014-01-01

    The authors analyse changes in exposure load and associated occupational risk, health state of workers engaged into contemporary polyvinyl chloride production. Consideration covered objective parameters--results of thorough medical examinations -and subjective ones--results of quantitative risk evaluation of general pathologic syndromes and life quality caused by health state. The latter were compared with general working population unexposed to the hazards. Findings are statistically significant increase of functional disorders risk connected with cardiovascular and nervous diseases. Correlation was found between cardiovascular diseases prevalence and exposure chemical load. Statistically significant differences were seen in all life quality components between the workers groups compared.

  15. Thermotropic rod-like mesogens as stabilizers for polyolefins and polyvinyl chloride

    NASA Astrophysics Data System (ADS)

    Burmistrov, V. A.; Kuvshinova, S. A.; Koifman, O. I.

    2016-02-01

    The main approaches to stabilization of polymers and requirements to anti-ageing agents are discussed. Considerable attention is paid to the progress in the studies of the stabilizing activity of various substances in polyolefin- and polyvinyl chloride-based compositions. Particular demand for environmentally benign organic heat stabilizers and antioxidants is noted. The so-called mesogenic structures serving as effective light and heat stabilizers for polymer composites are presented. The effects of mesogens on the supramolecular structure of polyethylene, deformation and relaxation properties and thermal parameters as well as melt flow index, tribological properties and other properties of polymer materials are discussed. The bibliography includes 112 references.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

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

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

    PubMed

    Li, Dongsheng; Cao, Hai

    2012-01-01

    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.

  18. Photochromic and microstructural properties of methyl orange doped poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Bhajantri, R. F.; Sali, Renuka; Ravindrachary, V.; Pujari, P. K.; Sheela, T.; Rathod, Sunil G.

    2013-02-01

    The effect of Methyl Orange (MO) dye on microstructural, optical and fluorescence properties of the polymer Poly(vinyl alcohol) (PVA) is studied. The FTIR study shows the appearance of new peaks indicates the interaction of MO with PVA. The UV-Vis study shows three absorption regions with the first two shows red shift and the third one shows blue shift and hence correspondingly three optical energy band gaps. In fluorescence study, it is observed that the intensity increases with increasing wavelength. These results are understood by invoking the hydrogen bonding and hydrophobic interaction between PVA and MO, forms the charge transfer complex (CTC).

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

    NASA Technical Reports Server (NTRS)

    Pepper, S. V.

    1974-01-01

    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.

  20. Multiplexed holographic data page storage on a polyvinyl alcohol/acrylamide photopolymer memory.

    PubMed

    Fernández, Elena; Ortuño, Manuel; Gallego, Sergi; Márquez, Andrés; García, Celia; Beléndez, Augusto; Pascual, Inmaculada

    2008-09-01

    Holographic data pages were multiplexed in different thickness layers of a polyvinyl alcohol/acrylamide photopolymer. This material is formed of acrylamide photopolymers, which are considered interesting materials for recording holographic memories. A liquid crystal device was used to modify the object beam and store the data pages. A peristrophic multiplexing method is used to store a large number of data pages in the same spot in the material. The bit error rate was calculated fitting the histograms of the images to determine what parameters improve the quality of the images.

  1. Low voltage vertical organic field-effect transistor with polyvinyl alcohol as gate insulator

    NASA Astrophysics Data System (ADS)

    Rossi, Lucieli; Seidel, Keli F.; Machado, Wagner S.; Hümmelgen, Ivo A.

    2011-11-01

    We report the preparation of low gate leakage current organic field effect transistors in vertical architecture using polyvinyl alcohol as gate insulator and C60 fullerene as n-type semiconductor in devices with gate, source, and drain electrodes of Al. Intermediate electrode and top electrode operate, respectively, as source and drain, or vice-versa, depending on polarity. In these devices the intermediate electrode (source or drain) is permeable to the electric field produced by the gate so that increased drain current is obtained at either increasingly negative gate voltage when the source is the intermediate electrode or increasingly positive gate voltage when the drain is the intermediate electrode.

  2. Fabrication of poly(vinyl carbazole) waveguides by oxygen ion implantation

    NASA Astrophysics Data System (ADS)

    Ghailane, Fatima; Manivannan, Gurusamy; Knystautas, Émile J.; Lessard, Roger A.

    1995-08-01

    Polymer waveguides were fabricated by ion implantation involving poly(vinyl carbazole) films. This material was implanted by oxygen ions (O ++ ) of energies ranging from 50 to 250 keV. The ion doses varied from 1010 to 1015 ions / cm2. The conventional prism-film coupler method was used to determine the waveguiding nature of the implanted and unimplanted films. The increase of the surface refractive index in the implanted layer has been studied by measuring the effective refractive index (neff) for different optical modes. Electron spectroscopy chemical analysis measurements were also performed to assess the effect of ion implantation on the polymer matrix.

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

    NASA Astrophysics Data System (ADS)

    Ger, Tzong-Rong; Huang, Hao-Ting; Huang, Chen-Yu; Hu, Keng-Shiang; Lai, Jun-Yang; Chen, Jiann-Yeu; Lai, Mei-Feng

    2014-05-01

    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 Fe3O4 nanoparticles would be released and delivered to cells.

  4. Catechol-derivatized poly(vinyl alcohol) as a coating molecule for magnetic nanoclusters

    NASA Astrophysics Data System (ADS)

    Burnand, David; Monnier, Christophe A.; Redjem, Anthony; Schaefer, Mark; Rothen-Rutishauser, Barbara; Kilbinger, Andreas; Petri-Fink, Alke

    2015-04-01

    Surface functionalization of superparamagnetic iron oxide nanoparticles (SPIONs) remains indispensable in promoting colloidal stability and biocompatibility. We propose a well-defined and characterized synthesis of a new catechol-functionalized RAFT (reversible addition-fragmentation chain transfer) poly(vinyl alcohol) polymer, which can be anchored onto hydrophobic SPIONs via a one-pot emulsion ligand exchange process. Both single and clustered nanoparticles are obtained and can be separated from each other. As clustered SPIONs are receiving increasing attention, this new macroligand might be of considerable interest for both basic and applied sciences.

  5. Characterization of nanocellulose reinforced semi-interpenetrating polymer network of poly(vinyl alcohol) & polyacrylamide composite films.

    PubMed

    Mandal, Arup; Chakrabarty, Debabrata

    2015-12-10

    Semi-interpenetrating polymer network (semi-IPN) of poly(vinyl alcohol)/polyacrylamide was reinforced with various doses of nanocellulose. The different composite films thus prepared were characterized with respect to their mechanical, thermal, morphological and barrier properties. The composite film containing 5 wt.% of nanocellulose showed the highest tensile strength. The semi-interpenetrating polymer network of poly(vinyl alcohol)/polyacrylamide; and its various composites with nanocellulose were almost identical in their thermal stability. Each of the composites however exhibited much superior stability with respect to the linear poly(vinyl alcohol) and crosslinked polyacrylamide. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited phase separated morphology where agglomerates of nanocellulose were found to be dispersed in the matrix of the semi-IPN. The moisture vapor transmission rate (MVTR) was the lowest for the film containing 5 wt.% of nanocellulose.

  6. Fabrication and characterization of methylene-blue-doped polyvinyl alcohol-polyacrylic acid blend for holographic recording.

    PubMed

    Ushamani, Mythili; Sreekumar, Krishnapillai; Kartha, Cheranellore S; Joseph, Rani

    2004-06-20

    A methylene-blue-sensitized polymer blend of polyvinyl alcohol and polyacrylic acid is fabricated and tested for holographic recording. It was found to have good characteristics such as high sensitivity, storage stability, ease of fabrication, and environmental stability. Optimization of the ratio of polyvinyl alcohol/polyacrylic acid, the sensitizer concentration, pH, energy, diffraction efficiency measurements, etc., have been done. pH is found to have a great influence on the recovery of the dye in this matrix. The results of experimental investigations into the properties of this new material are reported.

  7. Evaluation of the Antimicrobial Effect of Chitosan/Polyvinyl Alcohol Electrospun Nanofibers Containing Mafenide Acetate

    PubMed Central

    Abbaspour, Mohammadreza; Sharif Makhmalzadeh, Behzad; Rezaee, Behjat; Shoja, Saeed; Ahangari, Zohreh

    2015-01-01

    Background: Chitosan, an important biodegradable and biocompatible polymer, has demonstrated wound-healing and antimicrobial properties. Objectives: This study aimed to evaluate the antimicrobial properties of mafenide acetate-loaded nanofibrous films, prepared by the electrospinning technique, using chitosan and polyvinyl alcohol (PVA). Materials and Methods: A 32 full factorial design was used for formulating electrospinning solutions. The chitosan percentage in chitosan/PVA solutions (0%, 10%, and 30%) and the drug content (0%, 20%, and 40%) were chosen as independent variables. The release rate of mafenide acetate from nanofibrous films and their microbial penetration were evaluated. The antimicrobial activity of different nanofibrous film formulations against Staphylococcus aureus and Pseudomonas aeruginosa was studied. Results: The results indicated that all nanofibrous films, with and without drug, can prevent bacterial penetration. Incorporation of mafenide acetate into chitosan/PVA nanofibers enhanced their antimicrobial activity against P. aeruginosa and S. aureus. Conclusions: Overall, the results showed that chitosan/polyvinyl alcohol (PVA) nanofibrous films are applicable for use as a wound dressing with protective, healing, and antimicrobial effects. PMID:26587214

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

    SciTech Connect

    Markowitz, J.S.; Gutterman, E.M. ); Schwartz, S.; Link, B.; Gorman, S.M. )

    1989-05-01

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

  9. Rheological and Performance Research on a Regenerable Polyvinyl Alcohol Fracturing Fluid.

    PubMed

    Shang, Xiaosen; Ding, Yunhong; Wang, Yonghui; Yang, Lifeng

    2015-01-01

    A regenerable polyvinyl alcohol/organic boron fracturing fluid system with 1.6 wt% polyvinyl alcohol (PVOH) and 1.2 wt% organic boron (OBT) was studied, and its main regeneration mechanism is the reversible cross-linking reaction between B(OH)4- and hydroxyl groups of PVOH as the change of pH. Results of rheology evaluations show that both the apparent viscosity and the thermal stability of the fracturing fluid decreased with the regeneration number of times increasing. In addition, the apparent viscosity of the fluid which was without regeneration was more sensitive to the shear action compared with that of the fluid with regeneration once or twice. When the fracturing fluid was without regeneration, the elasticity was dominating due to the three-dimensional network structure of the formed gel; the viscosity gradually occupied the advantage when the fracturing fluid was regenerated once or twice. The settling velocity of proppant was accelerated by both the regeneration process and the increasing temperature, but it was decelerated when the proppant ratio increased. Results of core damage tests indicate that less permeability damage was caused by the PVOH/OBT fracturing fluid compared with that caused by the guar gum fracturing fluid after gel breaking.

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

    PubMed

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

    2008-05-01

    We investigate the effects of clay proportion and nanoscale dispersion in the dielectric response of poly(vinyl alcohol)-bentonite nanocomposites. The dielectric study was performed using the thermally stimulated depolarization current technique, covering the temperature range of the secondary and high-temperature relaxation processes. Important changes in the secondary relaxations are observed at low clay contents in comparison with neat poly(vinyl alcohol) (PVA). The high-temperature processes show a complex peak, which is a combination of the glass-rubber transition and the space-charge relaxations. The analysis of these processes shows the existence of two segmental relaxations for the nanocomposites. Dielectric results were complemented by calorimetric experiments using differential scanning calorimetry. Morphologic characterization was performed by x-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM and XRD results show a mixture of intercalated and exfoliated clay dispersion in a trend that promotes the exfoliated phase as the bentonite content diminishes. Dielectric and morphological results indicate the existence of polymer-clay interactions through the formation of hydrogen bounds and promoted by the exfoliated dispersion of the clay. These interactions affect not only the segmental dynamics, but also the secondary local dynamics of PVA.

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

    PubMed

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

    2011-09-20

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

  12. Lidocaine stability in cardioplegic solution stored in glass bottles and polyvinyl chloride bags.

    PubMed

    Lackner, T E; Baldus, D; Butler, C D; Amyx, C; Kessler, G

    1983-01-01

    The stability of lidocaine hydrochloride in buffered cardioplegic solutions stored in glass and polyvinyl chloride bags was studied. Concentrations of lidocaine (incorporated as the hydrochloride salt) were measured in buffered cardioplegic solutions containing potassium chloride, sodium bicarbonate, dextrose, and sodium chloride. Solutions were stored at 22 +/- 2 degrees C and 4 degrees C in glass bottles and 500-ml and 250-ml polyvinyl chloride (PVC) containers; some 250-ml PVC bags were underfilled to study the effects of varying surface area-volume ratios. Lidocaine concentrations were measured using a homogeneous enzyme immunoassay (EMIT, Syva Corporation) on days 0, 1, 2, 7, and 21. Lidocaine concentrations decreased significantly in all PVC bags stored at 22 degrees C and in underfilled PVC bags stored at 4 degrees C. Lidocaine loss in PVC bags appeared to result from sorption. It is concluded that lidocaine is stable in cardioplegic solutions when these are refrigerated and stored in glass containers or filled large-volume PVC bags for 21 days.

  13. Wound healing modulation by a latex protein-containing polyvinyl alcohol biomembrane.

    PubMed

    Ramos, Márcio V; de Alencar, Nylane Maria N; de Oliveira, Raquel S B; Freitas, Lyara B N; Aragão, Karoline S; de Andrade, Thiago Antônio M; Frade, Marco Andrey C; Brito, Gerly Anne C; de Figueiredo, Ingrid Samantha T

    2016-07-01

    In a previous study, we performed the chemical characterization of a polyvinyl alcohol (PVA) membrane supplemented with latex proteins (LP) displaying wound healing activity, and its efficacy as a delivery system was demonstrated. Here, we report on aspects of the mechanism underlying the performance of the PVA-latex protein biomembrane on wound healing. LP-PVA, but not PVA, induced more intense leukocyte (neutrophil) migration and mast cell degranulation during the inflammatory phase of the cicatricial process. Likewise, LP-PVA induced an increase in key markers and mediators of the inflammatory response (myeloperoxidase activity, nitric oxide, TNF, and IL-1β). These results demonstrated that LP-PVA significantly accelerates the early phase of the inflammatory process by upregulating cytokine release. This remarkable effect improves the subsequent phases of the healing process. The polyvinyl alcohol membrane was fully absorbed as an inert support while LP was shown to be active. It is therefore concluded that the LP-PVA is a suitable bioresource for biomedical engineering.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

  15. How To Learn and Have Fun with Poly(Vinyl Alcohol) and White Glue

    NASA Astrophysics Data System (ADS)

    de Zea Bermudez, V.; Passos de Almeida, P.; Féria Seita, J.

    1998-11-01

    The general behavior of Newtonian, shear-thinning, shear-thickening, thixotropic, negative thixotropic, and viscoelastic fluids is characterized and briefly discussed in terms of existing theoretical models. Whenever possible, examples of these types of fluids taken from everyday life are given for better understanding. This theoretical introduction is the basis for same, simple, and inexpensive laboratory work employing no special glassware and generally done by pairs of students. The work involves the synthesis of two well-known viscoelastic materials displaying unique properties: poly(vinyl alcohol) (PVA) and white glue, a poly(vinyl acetate)-based emulsion. The students are asked to perform a series of representative mechanical tests on both gels and to describe their observations in full detail. In particular, they are expected to recognize and identify the origin of the intriguing behaviors found (elasticity, spinability, self-siphoning effect, die-swell effect, Weissenberg effect). The tests include the preparation of fibers by extrusion, introducing concepts such as water solubility, hydrogen bonding, and glass transition temperature. The long list of questions, which ideally should be answered at the end of the laboratory work, allows the students to apply the new concepts acquired.

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

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

  17. Water resistance and thermal properties of polyvinyl alcohol-starch fiber blend film

    NASA Astrophysics Data System (ADS)

    Salleh, M. S. N.; Nor, N. N. Mohamed; Mohd, N.; Draman, S. F. Syed

    2017-02-01

    The growing attention of starch fiber (SF) has led to the innovation of Polyvinyl Alcohol-SF (PVA-SF) blends. This blend is regarded as the biodegradable material which aims to reduce the accumulation of synthetic polymer solid waste derived from petroleum. In this study, the thermal blending characterizations of PVA-SF were investigated by differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The water resistance of the blend was also evaluated to study the polarity of the blends. The blend was prepared by plasticizing the polyvinyl alcohol with glycerol and distilled water with the addition of starch fiber. The incorporation of SF to the blends was at 10 wt% to 50 wt% composition. Based on the thermal analysis, PVA-SF blends were suitable for processing at high temperatures, which can be seen by the shifted onset degradation temperature to a higher temperature. This is because cyclic hemiacetals which were provided by SF can act to prevent the thermal attacks. Conversely, increasing the starch fiber proportion to the film blend reduce the endothermic peak amplitude in the DSC thermogram. It was found that PVA-SF blend at the higher composition of SF had the highest water resistance. This may be attributed to the content of fibre in SF which is hydrophilic.

  18. Rheological and Performance Research on a Regenerable Polyvinyl Alcohol Fracturing Fluid

    PubMed Central

    Shang, Xiaosen; Ding, Yunhong; Wang, Yonghui; Yang, Lifeng

    2015-01-01

    A regenerable polyvinyl alcohol/organic boron fracturing fluid system with 1.6 wt% polyvinyl alcohol (PVOH) and 1.2 wt% organic boron (OBT) was studied, and its main regeneration mechanism is the reversible cross-linking reaction between B(OH)4- and hydroxyl groups of PVOH as the change of pH. Results of rheology evaluations show that both the apparent viscosity and the thermal stability of the fracturing fluid decreased with the regeneration number of times increasing. In addition, the apparent viscosity of the fluid which was without regeneration was more sensitive to the shear action compared with that of the fluid with regeneration once or twice. When the fracturing fluid was without regeneration, the elasticity was dominating due to the three-dimensional network structure of the formed gel; the viscosity gradually occupied the advantage when the fracturing fluid was regenerated once or twice. The settling velocity of proppant was accelerated by both the regeneration process and the increasing temperature, but it was decelerated when the proppant ratio increased. Results of core damage tests indicate that less permeability damage was caused by the PVOH/OBT fracturing fluid compared with that caused by the guar gum fracturing fluid after gel breaking. PMID:26641857

  19. Analysis of polyvinyl alcohol microbubbles in human blood plasma using capillary electrophoresis.

    PubMed

    Josefsson, Leila; Larsson, Malin K; Bjällmark, Anna; Emmer, Åsa

    2016-04-01

    Recently, a new type of ultrasound contrast agent that consists of air-filled microbubbles stabilized with a shell of polyvinyl alcohol was developed. When superparamagnetic nanoparticles of iron oxide are incorporated in the polymer shell, a multimodal contrast agent can be obtained. The biodistribution and elimination pathways of the polyvinyl alcohol microbubbles are essential to investigate, which is limited with today's techniques. The aim of the present study was, therefore, to develop a method for qualitative and quantitative analysis of microbubbles in biological samples using capillary electrophoresis with ultraviolet detection. The analysis parameters were optimized to a wavelength at 260 nm and pH of the background electrolyte ranging between 11.9 and 12. Studies with high-intensity ultrasonication degraded microbubbles in water showed that degraded products and intact microbubbles could be distinguished, thus it was possible to quantify the intact microbubbles solely. Analysis of human blood plasma spiked with either plain microbubbles or microbubbles with nanoparticles demonstrated that it is possible to separate them from biological components like proteins in these kinds of samples.

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

    PubMed

    Beckwith, Kai M; Sikorski, Pawel

    2013-12-01

    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.

  1. A novel biobased plasticizer of epoxidized cardanol glycidylether: Synthesis and application in soft poly(vinyl chloride) films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A novel plasticizer derived from cardanol, epoxied cardanol glycidyl ether (ECGE), was synthesized and characterized by 1H-NMR and 13C-NMR. Effects of the ECGE combined with dioctyl phthalate (DOP), a commercial plasticizer, in soft poly(vinyl chloride) (PVC) films were studied. Dynamic mechanical a...

  2. 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 ...

  3. Rheological characterization of solutions and thin films made from amylose-hexadecylammonium chloride inclusion complexes and polyvinyl alcohol

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The rheological properties of aqueous solutions and films made from blends of polyvinyl alcohol (PVOH) and amylose-hexadecylammonium chloride inclusion complexes (Hex-Am) were investigated to better understand the polymer interactions and processing parameters. Aqueous solutions of Hex-Am displayed ...

  4. Morphological influence of cellulose nanoparticles (CNs) from cottonseed hulls on rheological properties of polyvinyl alcohol/CN suspensions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This work aims to extract and characterize fibrous, rod-like and spherical cellulose nanoparticles (CNs) from cottonseed hull and to investigate the structure-morphology-rheology relationships. The rheological behavior of poly(vinyl alcohol) (PVA)/CNs suspensions was also examined to guide the solve...

  5. Poly(vinyl alcohol) composite films with high percent elongation prepared from amylose-fatty ammonium salt inclusion complexes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Amylose inclusion complexes prepared from cationic fatty ammonium salts and jet-cooked high amylose starch were combined with poly(vinyl alcohol) (PVOH) to form glycerol-plasticized films. Their tensile properties were compared with similar films prepared previously with analogous anionic fatty acid...

  6. Chitosan functionalized poly(vinyl alcohol) for prospects biomedical and industrial applications: A review.

    PubMed

    Rafique, Ammara; Mahmood Zia, Khalid; Zuber, Mohammad; Tabasum, Shazia; Rehman, Saima

    2016-06-01

    Chitin and chitosan are amino polysaccharides having multidimensional properties, such as biocompatibility, biodegradability, antibacterial properties and non-toxicity, muco-adhesivity, adsorption properties, etc., and thus they can be widely used in variety of areas. Although human history mainly relies on the biopolymers, however synthetic materials like polyvinyl alcohol (PVA) have good mechanical, chemical and physical properties. Functionalization of PVA with chitin and chitosan is considered very appropriate for the development of well-designed biomaterials such as biodegradable films, for membrane separation, for tissue engineering, for food packaging, for wound healing and dressing, hydro gels formation, gels formation, etc. Considering versatile properties of the chitin and chitosan, and wide industrial and biomedical applications of PVA, this review sheds a light on chitin and chitosan based PVA materials with their potential applications especially focusing the bio-medical field. All the technical scientific issues have been addressed highlighting the recent advancement.

  7. Hybrid Polyvinyl Alcohol and Cellulose Fiber Pulp Instead of Asbestos Fibers in Cement-Based Composites

    NASA Astrophysics Data System (ADS)

    Shokrieh, M. M.; Mahmoudi, A.; Shadkam, H. R.

    2015-05-01

    The Taguchi method was used to determine the optimum content of a four-parameters cellulose fiber pulp, polyvinyl alcohol (PVA) fibers, a silica fume, and bentonite for cement-based composite sheets. Then cement composite sheets from the hybrid of PVA and the cellulose fiber pulp were manufactured, and their moduli of rapture were determined experimentally. The result obtained showed that cement composites with a hybrid of PVA and cellulose fiber pulp had a higher flexural strength than cellulose-fiber- reinforced cement ones, but this strength was rather similar to that of asbestos-fiber-reinforced cement composites. Also, using the results of flexural tests and an analytical method, the tensile and compressive moduli of the hybrid of PVA and cement sheet were calculated. The hybrid of PVA and cellulose fiber pulp is proposed as an appropriate alternative for substituting asbestos in the Hatschek process.

  8. Fabrication and Characterization of Graphene/Graphene Oxide-Based Poly(vinyl alcohol) Nanocomposite Membranes

    NASA Astrophysics Data System (ADS)

    Hieu, Nguyen Huu; Long, Nguyen Huynh Bach Son; Kieu, Dang Thi Minh; Nhiem, Ly Tan

    2016-05-01

    Graphene (GE)- or graphene oxide (GO)-based poly(vinyl alcohol) (PVA) nanocomposite membranes have been prepared by the solution blending method. Raman spectra and atomic force microscopy images confirmed that GE and GO were synthesized with average thickness of 0.901 nm and 0.997 nm, respectively. X-ray diffraction patterns indicated good exfoliation of GE or GO in the PVA matrix. Fourier-transform infrared spectra revealed the chemical fractions of the nanocomposite membranes. Differential scanning calorimetry results proved that the thermal stability of the nanocomposite membranes was enhanced compared with neat PVA membrane. Transmission electron microscopy images revealed good dispersion of GE or GO sheets in the PVA matrix with thickness in the range of 19 nm to 39 nm. As a result, good compatibility between GE or GO and PVA was obtained at 0.5 wt.% filler content.

  9. Nanofibrillated Cellulose and Copper Nanoparticles Embedded in Polyvinyl Alcohol Films for Antimicrobial Applications

    PubMed Central

    Zhong, Tuhua; Oporto, Gloria S.; Jaczynski, Jacek; Jiang, Changle

    2015-01-01

    Our long-term goal is to develop a hybrid cellulose-copper nanoparticle material as a functional nanofiller to be incorporated in thermoplastic resins for efficiently improving their antimicrobial properties. In this study, copper nanoparticles were first synthesized through chemical reduction of cupric ions on TEMPO nanofibrillated cellulose (TNFC) template using borohydride as a copper reducing agent. The resulting hybrid material was embedded into a polyvinyl alcohol (PVA) matrix using a solvent casting method. The morphology of TNFC-copper nanoparticles was analyzed by transmission electron microscopy (TEM); spherical copper nanoparticles with average size of 9.2 ± 2.0 nm were determined. Thermogravimetric analysis and antimicrobial performance of the films were evaluated. Slight variations in thermal properties between the nanocomposite films and PVA resin were observed. Antimicrobial analysis demonstrated that one-week exposure of nonpathogenic Escherichia coli DH5α to the nanocomposite films results in up to 5-log microbial reduction. PMID:26137482

  10. Simple but Strong: A Mussel-Inspired Hot Curing Adhesive Based on Polyvinyl Alcohol Backbone.

    PubMed

    Mu, Youbing; Wan, Xiaobo

    2016-03-01

    The strong adhesion ability of mussel foot-byssal proteins (Mfps) has inspired scientists to develop novel materials for strong and reversible adhesion, coating, antifouling, and many other applications. However, in many cases, the high costs and the tedious preparation steps of such bioinspired materials hamper the process to push them into practical application. Here a simple but effective way (one step) is presented to synthesize a mussel-inspired glue from two cheap commercially available materials: polyvinyl alcohol (PVA) and 3,4-dihydroxybenzaldehyde (DBA). This bioinspired hot curing adhesive exhibits a strong bonding ability as high as 17.3 MPa on stainless steel surfaces, which surpasses most of the commercially available adhesives.

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

    PubMed

    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

    2014-11-04

    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.

  12. Copper-containing polyvinyl alcohol composite systems: Preparation, characterization and biological activity

    NASA Astrophysics Data System (ADS)

    Reza Hajipour, Abdol; Mohammadsaleh, Fatemeh; Reza Sabzalian, Mohammad

    2015-08-01

    The present investigation reports, the complex formation of Cu(II) with polyvinyl alcohol (PVA) and the synthesis of PVA-stabilized Cu2O particles. This PVA-Cu2O composite has been prepared via chemical reduction method using PVA-Cu(II) complex as precursor. At first, Cu(II) ions were stabilized in PVA matrix via complex formation with OH groups; subsequently, this PVA-Cu(II) macromolecular complex as precursor reacted with ascorbic acid as reducing agent at pH=12 to prepare PVA-Cu2O composite. The products were characterized by FTIR, XRD, FE-SEM, HRTEM, Visible Spectroscopy and atomic absorption. In the following, the antibacterial properties of as-prepared composites were examined against Gram-positive (Bacillus thuringiensis) and Gram-negative bacteria (Escherichia coli), and the results showed excellent antibacterial activity of these materials.

  13. Photochromic properties of the N-Salicylideneaniline in Polyvinyl Butyral matrix: Experimental and theoretical investigations

    NASA Astrophysics Data System (ADS)

    Shahab, Siyamak; Filippovich, Liudmila; Aharodnikova, M.; Almodarresiyeh, Hora A.; Hajikolaee, Fatemeh Haji; Kumar, Rakesh; Mashayekhi, Mahsa

    2017-04-01

    In the present work, isomerization, photophysical properties, thermal conductivity (λ) and spectral study of the N-Salicylideneaniline: 2-[(E)-(phenylimino)methyl]phenol (SA) under the action of UV radiation in the Polyvinyl Butyral (PVB) matrix were studied using the Indicator method and Density Functional Theory (DFT). The electronic absorption spectra of SA and its isomers (SA1 and SA2) in dimethylformamide (DMF) solutions were also calculated. The nature of absorption bands of SA, SA1 and SA2 in the visible and near ultraviolet spectral regions was interpreted. The excitation energies, electronic transitions and oscillator strengths for SA, SA1 and SA2 have also been calculated. Thermal Conductivity of PVB-films containing SA before and after UV radiation was also measured. A Photochromic PVB - film on the basis of SA for application in optical devices and display technologies was made.

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

    PubMed

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

    2011-12-01

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

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

    PubMed

    Patra, Niranjan; Martinová, Lenka; Stuchlik, Martin; Černík, Miroslav

    2015-04-20

    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 15 min. 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.

  16. Characterization and application of zeolitic imidazolate framework-8@polyvinyl alcohol nanofibers mats prepared by electrospinning

    NASA Astrophysics Data System (ADS)

    Fan, Xiaoxiao; Yu, Linling; Li, Lianghao; Yang, Cao; Wen, Junjie; Ye, Xiaokun; Cheng, Jianhua; Hu, Yongyou

    2017-02-01

    In this study, Zeolitic imidazolate framework-8@polyvinyl alcohol (ZIF-8@PVA) nanofibers were creatively fabricated by electrospinning technique, and the nanofibers membranes were characterized by SEM, TEM, XRD, FTIR, TG, DSC, DTA, BET. Its thermal stability, mechanical property, water stability and adsorption nature were also performed. The optimized fabrication parameter of the ZIF-8@PVA was 10 wt% and the uniform diameters of the nanofibers has been obtained. In addition, the ZIF-8@PVA nanofibers displayed unique properties such as a water stable and flexible structure. The adsorption test for Congo red treatment revealed that the nanofibers had a great adsorption performance. The results indicated that the nonwoven fiber mats had a great potential as a new type of membrane adsorbents in wastewater purification. The possible mechanism of CR adsorption onto ZIF-8@PVA was researched.

  17. Survival of allochthonous bacteria in still mineral water bottled in polyvinyl chloride (PVC) and glass.

    PubMed

    Moreira, L; Agostinho, P; Morais, P V; da Costa, M S

    1994-09-01

    The mortality of Escherichia coli, Enterobacter cloacae, Klebsiella pneumoniae and Pseudomonas aeruginosa, based on the culturability of these bacteria, was assessed in non-carbonated mineral water, bottled in polyvinyl chloride (PVC) containing the indigenous flora, sterile mineral water bottled in PVC, sterile mineral water in glass containers, and sterile tap water in glass containers. There was a general decrease in the culturability of these organisms in the four test waters, except that Ps. aeruginosa grew in sterile tap water. Escherichia coli and Kl. pneumoniae had the highest mortality rates under the conditions tested, while Ent. cloacae had a very low and constant mortality rate that would have resulted in the persistence of this organism in mineral water for a long period of time. After a sharp initial decrease in culturability, Ps. aeruginosa also had a very low mortality rate in mineral water bottled in PVC.

  18. Tuning optical and three photon absorption properties in graphene oxide-polyvinyl alcohol free standing films

    NASA Astrophysics Data System (ADS)

    Karthikeyan, B.; Udayabhaskar, R.; Hariharan, S.

    2016-07-01

    We report the optical and nonlinear optical properties of graphene oxide (GO)-polyvinyl alcohol (PVA) free standing films. The composite polymer films were prepared in ex-situ method. The variation in optical absorption spectra and optical constants with the amount of GO loading was noteworthy from the optical absorption spectroscopic studies. Nonlinear optical studies done at 532 nm using 5 ns laser pulses show three photon absorption like behaviour. Both steady state and time resolved fluorescence studies reveal that the GO was functioning as a pathway for the decay of fluorescence from PVA. This is attributed to the energy level modifications of GO through hydroxyl groups with PVA. Raman spectroscopy also supports the interaction between GO and PVA ions through OH radicals.

  19. Activation of Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol) using a Supramolecular Trigger†

    PubMed Central

    Phillips, Daniel J.; Congdon, Thomas R.; Gibson, Matthew I.

    2016-01-01

    Antifreeze (glyco)proteins (AF(G)Ps) have potent ice recrystallisation inhibition (IRI) activity – a desirable phenomenon in applications such as cryopreservation, frozen food and more. In Nature AF(G)P activity is regulated by protein expression levels in response to an environmental stimulus; temperature. However, this level of regulation is not possible in synthetic systems. Here, a synthetic macromolecular mimic is introduced, using supramolecular assembly to regulate activity. Catechol-terminated poly(vinyl alcohol) was synthesised by RAFT polymerization. Upon addition of Fe3+, larger supramolecular star polymers form by assembly with two or three catechols. This increase in molecular weight effectively ‘switches on’ the IRI activity and is the first example of external control over the function of AFP mimetics. This provides a simple but elegant solution to the challenge of external control of AFP-mimetic function. PMID:28003855

  20. Model fire tests on polyphosphazene rubber and polyvinyl chloride (PVC)/nitrile rubber foams

    NASA Technical Reports Server (NTRS)

    Widenor, W. M.

    1978-01-01

    A video tape record of model room fire tests was shown, comparing polyphosphazene (P-N) rubber and polyvinyl chloride (PVC)/nitrile rubber closed-cell foams as interior finish thermal insulation under conditions directly translatable to an actual fire situation. Flashover did not occur with the P-N foam and only moderate amounts of low density smoke were formed, whereas with the PVC/nitrile foam, flashover occurred quickly and large volumes of high density smoke were emitted. The P-N foam was produced in a pilot plant under carefully controlled conditions. The PVC/nitrile foam was a commercial product. A major phase of the overall program involved fire tests on P-N open-cell foam cushioning.

  1. Poly(vinyl alcohol) Physical Hydrogels: Matrix-Mediated Drug Delivery Using Spontaneously Eroding Substrate

    PubMed Central

    2016-01-01

    Poly(vinyl alcohol) hydrogels have a long and successful history of applications in biomedicine. Historically, these matrices were developed to be nondegradable—limiting their utility to applications as permanent implants. For tissue engineering and drug delivery, herein we develop spontaneously eroding physical hydrogels based on PVA. We characterize in detail a mild, noncryogenic method of producing PVA physical hydrogels using poly(ethylene glycol) as a gelating agent, and investigate PVA molar mass as a means to define the kinetics of erosion of these biomaterials. PVA hydrogels are characterized for associated inflammatory response in adhering macrophages, antiproliferative effects mediated through delivery of cytotoxic drugs to myoblasts, and pro-proliferative activity achieved via presentation of conjugated growth factors to endothelial cells. Together, these data present a multiangle characterization of these novel multifunctional matrices for applications in tissue engineering and drug delivery mediated by implantable biomaterials. PMID:26958864

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

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

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

  3. Non-isothermal crystallization kinetics of eucalyptus lignosulfonate/polyvinyl alcohol composite.

    PubMed

    Ye, De-Zhan; Zhang, Xi; Gu, Shaojin; Zhou, Yingshan; Xu, Weilin

    2017-04-01

    The nonisothermal crystallinization kinetic was performed on Polyvinyl alcohol (PVA) mixed with eucalyptus lignosulfonate calcuim (HLS) as the biobased thermal stabilizer, which was systematically analyzed based on Jeziorny model, Ozawa equation and the Mo method. The results indicated that the entire crystallization process took place through two main stages involving the primary and secondary crystallization processes. The Mo method described nonisothermal crystallization behavior well. Based on the results of the half time for completing crystallization, kc value in Jeziorny model, F(T) value in Mo method and crystallization activation energy, it was concluded that low loading of HLS accelerated PVA crystallization process, however, the growth rate of PVA crystallization was impeded at high content of HLS.

  4. Behavior and products of mechano-chemical dechlorination of polyvinyl chloride and poly (vinylidene chloride).

    PubMed

    Xiao, Xiao; Zeng, Zigao; Xiao, Songwen

    2008-02-28

    The mechano-chemical (MC) dechlorination of polyvinyl chloride (PVC) and polyvinylidene chloride (PVDC) was performed by mechanical milling PVC/PVDC powder with zinc powder in a planetary ball mill, and the products of dechlorination were characterized by Infrared spectra (IR), X-ray diffraction (XRD), Raman spectroscopy, gas chromatography-mass spectrometry (GC-MS), and 13C solid-state nuclear magnetic resonance (NMR). The experimental results show that PVC/PVDC can be easily dechlorinated by milling with zinc powder, and formed various kinds of inorganic and organic products. Inorganic compounds included Zn2OCl(2).2H2O, Zn5(OH)8Cl2.H2O etc., and organic products involved diamond-like carbon, carbyne fragment, polyacetylene etc. Organic products formed following the paths of dechlorination, dehydrochlorination, crosslink, and oxidation. The mechano-chemical dechlorination process of PVC/PVDC may be an effective approach for carbyne synthesizing in the appropriate condition.

  5. Evaluation of electrospun polyvinyl chloride/polystyrene fibers as sorbent materials for oil spill cleanup.

    PubMed

    Zhu, Haitao; Qiu, Shanshan; Jiang, Wei; Wu, Daxiong; Zhang, Canying

    2011-05-15

    A novel, high-capacity oil sorbent consisting of polyvinyl chloride (PVC)/polystyrene (PS) fiber was prepared by an electrospinning process. The sorption capacity, oil/water selectivity, and sorption mechanism of the PVC/PS sorbent were studied. The results showed that the sorption capacities of the PVC/PS sorbent for motor oil, peanut oil, diesel, and ethylene glycol were 146, 119, 38, and 81 g/g, respectively. It was about 5-9 times that of a commercial polypropylene (PP) sorbent. The PVC/PS sorbent also had excellent oil/water selectivity (about 1000 times) and high buoyancy in the cleanup of oil over water. The SEM analysis indicated that voids among fibers were the key for the high capacity. The electrospun PVC/PS sorbent is a better alternative to the widely used PP sorbent for oil spill cleanup.

  6. Covalent immobilization of mixed proteases, trypsin and chymotrypsin, onto modified polyvinyl chloride microspheres.

    PubMed

    Li, Dong-Fang; Ding, Hao-Chen; Zhou, Tao

    2013-11-06

    A commercially available trypsin-chymotrypsin mixture was covalently immobilized onto modified polyvinyl chloride (PVC) microspheres, which were activated by the subsequent treatment of PVC microspheres with ethylenediamine and glutaraldehyde. The immobilized mixed protease was characterized by FT-IR and SEM analyses. Immobilization conditions were optimized by Box-Behnken design and the response surface method. The activity of the immobilized mixed protease prepared under optimal conditions (pH 6.6, 23 °C, 2 h) reached 1341 U/g. Compared with the free form, the immobilized enzyme possesses a slightly higher optimal pH value and a wider pH-activity profile, superior thermal stability, and a higher Km value. Reusability of the immobilized mixed protease indicated that >70% of the original activity was retained after having been recycled six times.

  7. Structurally Enhanced Self-Plasticization of Poly(vinyl chloride) via Click Grafting of Hyperbranched Polyglycerol.

    PubMed

    Lee, Kyu Won; Chung, Jae Woo; Kwak, Seung-Yeop

    2016-12-01

    A highly self-plasticized poly(vinyl chloride) (PVC) is demonstrated for the first time via click grafting of hyperbranched polyglycerol (HPG). The plasticizing effect of the grafted HPG on PVC is systematically investigated by various analytical methods. The amorphous and bulky dendritic structure of HPG efficiently increases the free volume of the grafted PVC, which leads to a remarkably lower glass transition temperature comparable to that of the conventional plasticized PVC. Viscoelastic analysis reveals that HPG considerably improves the softness of the grafted PVC at room temperature and promotes the segmental motion in the system. The HPG-grafted PVC films exhibit an exceptional stretchability unlike the mixture of PVC and HPG because the covalent attachment of HPG to PVC allows it to maintain its homogeneous and well-organized architecture under tensile stretching. The work provides valuable insights into the design of highly flexible and stretchable polymeric materials by means of introducing hyperbranched side chains.

  8. Radiolytic formation of Ag clusters in aqueous polyvinyl alcohol solution and hydrogel matrix

    NASA Astrophysics Data System (ADS)

    Kumar, Manmohan; Varshney, Lalit; Francis, Sanju

    2005-05-01

    Ag+ ions, in aqueous polyvinyl alcohol (PVA) solution and in PVA hydrogel matrix have been gamma radiolytically reduced to produce Ag clusters. UV-visible absorption spectral characteristics of Ag clusters obtained under different gamma dose, Ag+ concentration, PVA concentration and crosslinking density of the gel used have been studied. The effect of Ag+ ions on the radiation crosslinking of the PVA chains, have also been investigated by viscosity measurements. The radiation-induced Ag+ ion reduction was followed by crosslinking of the PVA chains. PVA was found to be a very efficient stabilizer to prevent aggregation of Ag clusters. The clusters produced in the hydrogel matrix were expected to be smaller than the pore size (∼2-20 nm) of the gels used in the study. These Ag clusters were unable to reduce methyl viologen (MV2+) chloride and were stable in air.

  9. A stimuli-responsive and bioactive film based on blended polyvinyl alcohol and cashew gum polysaccharide.

    PubMed

    Silva, Fábio E F; Batista, Karla A; Di-Medeiros, Maria C B; Silva, Cassio N S; Moreira, Bruna R; Fernandes, Kátia F

    2016-01-01

    In this study, a stimuli-responsive, biodegradable and bioactive film was produced by blending cashew gum polysaccharide (CGP) and polyvinyl alcohol (PVA). The film presented malleability and mechanical properties enabling an easy handling. Wetting the film changed the optical property from opacity to levels of transparency higher than 70% and resulted in up to 2-fold increase in its superficial area. Different swelling indexes were obtained varying the pH of solvent, which allows classifying the CGP/PVA film as pH sensitive stimuli-responsive material. The bioactivity was achieved through covalent immobilization of papain, which remained active after storage of CGP/PVA-papain film for 24h in the presence of buffer or in a dry form. These results evidenced that CGP/PVA-papain film is a very promising material for biomedical applications.

  10. Stability of latanoprost in an ophthalmic lipid emulsion using polyvinyl alcohol.

    PubMed

    Sakai, Yusuke; Yasueda, Shin-Ichi; Ohtori, Akira

    2005-11-23

    Latanoprost in water is not stable against heat stress due to hydrolysis of the isopropyl ester in the latanoprost molecule. Therefore, the storage condition of latanoprost ophthalmic solution, Xalatan brand, was in a low temperature (2-8 degrees C). We formulated a favorable ophthalmic lipid emulsion of latanoprost using polyvinyl alcohol as emulsifier which showed a good heat stability. The assays of the latanoprost ophthalmic lipid emulsions adjusted to pH 5.0, 6.0 and 7.0 were 100.4%, 100.7% and 99.2% after storage for 4 weeks at 60 degrees C, respectively. The possibility of room temperature storage for the latanoprost ophthalmic lipid emulsion was demonstrated.

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

    PubMed

    Messinger, Horst; Bär, Albert

    2014-10-01

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

  12. Electro-optical properties of poly(vinyl acetate)/polyindole composite film

    NASA Astrophysics Data System (ADS)

    Bhagat, D. J.; Bajaj, N. S.; Dhokane, G. R.

    2016-05-01

    In present work, electrical and optical properties of poly(vinyl acetate)/polyindole (PVAc/PIN) composite film are reported. The prepared composite was characterized via X-ray diffraction (XRD), UV-Vis spectroscopy and DC conductivity measurements. The polymer chain separation was determined using XRD analysis. An attempt has been made to study the temperature dependence of DC conductivity of PVAc/PIN composite in temperature range 308-373 K. The DC conductivity initially increases and reaches to 2.45×10-7 S/cm. The optical band gap value of composite is determined as 4.77 eV. The semiconducting nature of composite observed from electronic as well as optical band gap and Arrhenius behavior of DC plot.

  13. Effects of PVA(Polyvinyl Alcohol) on Supercooling Phenomena of Water

    NASA Astrophysics Data System (ADS)

    Kumano, Hiroyuki; Saito, Akio; Okawa, Seiji; Takizawa, Hiroshi

    In this paper, effects of polymer additive on supercooling of water were investigated experimentally. Poly-vinyl alcohol (PVA) were used as the polymer, and the samples were prepared by dissolving PVA in ultra pure water. Concentration, degree of polymerization and saponification of PVA were varied as the experimental parameters. The sample was cooled, and the temperature at the instant when ice appears was measured. Since freezing of supercooled water is statistical phenomenon, many experiments were carried out and average degrees of supercooling were obtained for each experimental condition. As the result, it was found that PVA affects nucleation of supercooling and the degree of supercooling increases by adding the PVA. Especially, it is found that the average degree of supercooling increases and the standard deviation of average degree of supercooling decreases with increase of degree of saponification of PVA. However, the average degree of supercooling are independent of the degree of polymerization of PVA in the range of this study.

  14. Adaptive microlens array based on electrically charged polyvinyl chloride/dibutyl phthalate gel

    NASA Astrophysics Data System (ADS)

    Xu, Miao; Ren, Hongwen

    2016-09-01

    We prepared an adaptive microlens array (MLA) using a polyvinyl chloride/dibutyl phthalate gel and an indium-tin-oxide (ITO) glass substrate. The gel forms a membrane on the glass substrate and the ITO electrode has a ring array pattern. When the membrane is electrically charged by a DC voltage, the surface of the membrane above each circular electrode in the ring array can be deformed with a convex shape. As a result, the membrane functions as an MLA. By applying a voltage from 20 to ˜65 V to the electrode, the focal length of each microlens can be tuned from 300 to ˜160 μm. The dynamic response time can by reduced largely by changing the polarity of the DC voltage. Due to the advantages of optical isotropy, compact structure, and good stability, our MLA has potential applications in imaging, biometrics, and electronic displays.

  15. Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds.

    PubMed

    Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B; Srinivasan, A

    2016-12-01

    Composite nanofibrous membranes based on sol-gel derived 45SiO2 24.5CaO 24.5 Na2O 6 P2O5 (bioglass, BG) and 43SiO2 24.5CaO 24.5 Na2O 6 P2O5 2Fe2O3 (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application.

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

    SciTech Connect

    Ger, Tzong-Rong; Huang, Hao-Ting; Hu, Keng-Shiang; Huang, Chen-Yu; Lai, Jun-Yang; Chen, Jiann-Yeu; Lai, Mei-Feng

    2014-05-07

    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.

  17. Photochemical and nonphotochemical hole burning in dimethyl-s-tetrazine in a polyvinyl carbazole film

    SciTech Connect

    Cuellar, E.; Castro, G.

    1981-01-01

    Hole burning as well as fluorescence line narrowing experiments have been performed on the system dimethyl-s-tetrazine in polyvinyl carbazole films at low temperatures. The first singlet electronic absorption bands are typical (300 cm-1 wide) of inhomogeneously broadened bands of guest molecules in amorphous organic hosts. In this paper, evidence is presented for both photochemical and nonphotochemical hole burning. The narrowest holes observed were lorentzian, had a width of 0.44 cm-1 at 1.8 K, and are believed to be of nonphotochemical origin. A model which envisions the guest molecules to occupy different sites in the polymer host with a distribution of energy barriers between sites is used to describe these observations. Finally, the fast (20 ps) relaxation time implied by the 0.44 cm-1 lorentzian linewidth is interpreted as indicative of the rate of site interconversion in the excited state.

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

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

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

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

    PubMed

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

    2010-01-01

    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.

  20. Aqueous leaching of di-2-ethylhexyl phthalate and "green" plasticizers from poly(vinyl chloride).

    PubMed

    Kastner, Joshua; Cooper, David G; Marić, Milan; Dodd, Patrick; Yargeau, Viviane

    2012-08-15

    A method was developed to assess leaching of several poly(vinyl chloride) (PVC) plasticizers in aqueous media using gas chromatography (GC), and compared to a gravimetric standard test method (ASTM Method D1239). The GC method was a more direct measurement of plasticizer concentration in the aqueous phase. The leaching of commercial plasticizers, as well as several series of "green" candidate plasticizers, were assessed as a function of their molecular characteristics and compared to the industry standard PVC plasticizer, di-2-ethylhexyl phthalate (DEHP). It was found that plasticizers containing longer alkyl chains or non-polar branching emanating from polar structural units, increased the hydrophobicity of the molecule and reduced its aqueous leaching rate. Several "green" plasticizer candidates were found to minimize aqueous leaching to rates ten times below that of DEHP; notably dioctyl succinate (DOS), dihexyl maleate (DHM), methyl cyclohexyl diester (MCDE), diethylhexyl succinate (DEHS), hexanediol dibenzoate (C6), and the commercially available Hexamoll® DINCH.

  1. Spectroelectrochemical Studies on Quinacridone by Using Poly(vinyl alcohol) Coating as Protection Layer

    PubMed Central

    Enengl, Sandra; Enengl, Christina; Stadler, Philipp; Neugebauer, Helmut; Sariciftci, Niyazi Serdar

    2015-01-01

    Spectroscopic measurements in the infrared range combined with electrochemistry are a powerful technique for investigation of organic semiconductors to track changes during oxidation and reduction (p- and n-doping) processes. For these measurements it is important that the studied material, mostly deposited as a thin film on an internal reflection element, does not dissolve during this characterization. In this study we introduce a technique that allows infrared spectroelectrochemical characterization of films of these materials for the first time. In many cases so far this has been impossible, due to solubility in the oxidized and/or reduced form. This novel technique is shown on thin films of quinacridone by adding a protection layer of poly(vinyl alcohol) (PVA). PMID:26013836

  2. Antimicrobial wound dressing nanofiber mats from multicomponent (chitosan/silver-NPs/polyvinyl alcohol) systems.

    PubMed

    Abdelgawad, Abdelrahman M; Hudson, Samuel M; Rojas, Orlando J

    2014-01-16

    Novel hybrid nanomaterials have been developed for antimicrobial applications. Here we introduce a green route to produce antibacterial nanofiber mats loaded with silver nanoparticles (Ag-NPs, 25 nm diameter) enveloped in chitosan after reduction with glucose. The nanofiber mats were obtained from colloidal dispersions of chitosan-based Ag-NPs blended with polyvinyl alcohol. Nanofibers (150 nm average diameter and narrow size distribution) were obtained by electrospinning and cross-linked with glutaraldhyde. The effect of crosslinking on the release of silver was studied by atomic absorption spectroscopy. Antimicrobial activity was studied by the viable cell-counting; mats loaded with silver and control samples (chitosan/PVA) with different degrees of cross-linking were compared for their effectiveness in reducing or halting the growth of aerobic bacteria. The results showed superior properties and synergistic antibacterial effects by combining chitosan with Ag-NPs.

  3. Lignosulfonate as reinforcement in polyvinyl alcohol film: Mechanical properties and interaction analysis.

    PubMed

    Ye, De-zhan; Jiang, Li; Hu, Xiao-qin; Zhang, Ming-hua; Zhang, Xi

    2016-02-01

    Recently, there has been a growing research interest on renewable composite due to sustainability concerns. This work demonstrated the possibility of using eucalyptus lignosulfonate calcium (HLS) particles as reinforcement in polyvinyl alcohol (PVA) matrix. 41% and 384.7% improvement of pure PVA tensile strength and Young's modulus were achieved with incorporation of 5 wt% HLS. The above results were ascribed to specific intermolecular interactions between HLS and PVA, suggested by the increasing PVA glass transition and crystalline relaxations temperature, depression of melting point with HLS incorporation. Moreover, this interaction was quantitatively determined by q value of -62.4±10.0 in Kwei equation. Additionally, the remarkable red shift of wavenumber corresponding to hydroxyl group also indicated the formation of strong hydrogen bond in HLS/PVA blend. SEM characterization confirmed that HLS/PVA blends are at least miscible.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  5. Electrochemical properties of poly(vinyl alcohol) and graphene oxide composite for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Theophile, Niyitanga; Jeong, Hae Kyung

    2017-02-01

    Poly(vinyl alcohol), PVA, polymer was successfully combined with graphene oxide (GO) and thermally reduced graphene oxide (RGO), respectively, to make composites and characterized for supercapacitor applications. PVA-RGO composite shows excellent electrochemical properties compared to PVA-GO composite. The capacitance of 190 Fg-1 is obtained from PVA-RGO composite which is larger than that (13 Fg-1) of PVA-GO composite. Electrochemical impedance of PVA-RGO is more than ten times smaller than that of PVA-GO at 20 kHz, demonstrating that PVA-RGO composite has a great advantage for supercapacitor applications compared to PVA, GO, RGO, and PVA-GO composite.

  6. The effect of electron beam irradiation on preparation of sago starch/polyvinyl alcohol foams

    NASA Astrophysics Data System (ADS)

    Wongsuban, Benchamaporn; Muhammad, Kharidah; Ghazali, Zulkafli; Hashim, Kamaruddin; Ali Hassan, Muhammad

    2003-10-01

    Blends of sago starch (SS)/polyvinyl alcohol (PVA) were irradiated with doses ranging from 10 to 30 kGy. Foams were then produced from these irradiated blends using a microwave. Changes in the degree of crosslinking, gel strength, thermal stability morphology of blends and linear expansion of foam with increasing irradiation doses were subsequently investigated. It was observed that the degree of crosslinking was important in maximizing the positive effect on foams produced. The gel strength of SS/PVA blends was affected by the irradiation. The crosslinking by the irradiation enhanced the thermal stability of SS/PVA blends. The results also revealed that the highest linear expansion of foams could be produced by irradiation blends at 15 kGy. Changes in blend morphology were observed upon irradiation.

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

    PubMed

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

    2013-08-07

    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.

  8. Synthesis and characterization of polyvinyl alcohol- carboxymethyl tamarind gum based composite films.

    PubMed

    Yadav, Indu; Rathnam, V S Sharan; Yogalakshmi, Yamini; Chakraborty, Subhabrata; Banerjee, Indranil; Anis, Arfat; Pal, Kunal

    2017-06-01

    The present study delineates the synthesis of novel composite films using polyvinyl alcohol and carboxymethyl tamarind gum. The microscopic study results confirmed the formation of composite matrices. FTIR spectroscopy suggested the occurrence of hydrogen-bonding amongst the components of the films. The extent of hydrogen bonding was composition-dependent which reached a critical higher limit at a particular composition. At the critical composition, the instantaneous and the intermediate polymer relaxation time were longer. All the films were found to be viscoelastic in nature. The melting endotherm was also highest for the composition described above. Ciprofloxacin loaded films showed excellent antimicrobial property against E. coli, suggesting that the drug was released in its active form. Cell proliferation study using human keratinocytes suggested better cell proliferation in the CMT containing films as compared to the control (PVA only) film. In gist, the developed films can be explored for skin tissue engineering and drug delivery applications.

  9. Synthesis and sorption properties of porous layers of cyclames on a modified polyvinyl chloride surface

    NASA Astrophysics Data System (ADS)

    Tsivadse, A. Yu.; Fridman, A. Ya.; Morozova, E. M.; Sokolova, N. P.; Voloshchuk, A. M.; Petukhova, G. A.; Bardyshev, I. I.; Gorbunov, A. M.; Polyakova, I. Ya.; Shapokhina, O. P.

    2012-03-01

    The structure and adsorption properties of the porous layers of synthesized ethanol-cyclames and sodium acetate cyclames on a surface of polyvinyl chloride (PVC) encapsulating fibers of the asbestos tissue of chrysotile asbestos are studied. It is established that PVC is linked to the silicon-oxygen chains of magnesium hydrosilicate; the capsule ensures the stability of the asbestos tissue under the action of the concentrated solutions of acids and alkalis; its exterior reproduces the fiber surface and has a typical microrelief; and there are voids in the layers. We conclude that the specific surface of layers and the volume of the adsorption space are larger than those of the initial fibers, and the statistical capacity upon the adsorption of water vapor and polar and nonpolar organic molecules depends on the nature and affinity for cyclames.

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    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.

  11. Interaction between vegetable oil based plasticizer molecules and polyvinyl chloride, and their plasticization effect

    NASA Astrophysics Data System (ADS)

    Haryono, Agus; Triwulandari, Evi; Jiang, Pingping

    2017-01-01

    Plasticizer molecules are low molecular weight compounds that are widely used in polymer industries especially in polyvinyl chloride (PVC) resin. As an additive in PVC resin, the important role of plasticizer molecules is to improve the flexibility and processability of PVC by lowering the glass transition temperature (Tg). However, the commercial plasticizer like di(2-ethylhexyl)phthalate (DEHP) is known to cause liver cancer, at least in laboratory rats. DEHP can leach out from PVC into blood, certain drug solutions and fatty foods, which has been detected in the bloodstream of patients undergoing transfusion. Vegetable oil based plasticizers have some attractive properties such as non-toxic, bio-degradable, good heat and light stability, renewable resources, and environmentally friendly. Here we discussed the main results and development of vegetable oil based plasticizer, and especially palm oil based plasticizer. The interaction between plasticizer and polymer was discussed from the properties of the plasticized polymeric material.

  12. Preparation of poly(vinyl alcohol)/kaolinite nanocomposites via in situ polymerization

    SciTech Connect

    Jia Xin; Li Yanfeng Zhang Bo; Cheng Qiong; Zhang Shujiang

    2008-03-04

    Poly(vinyl alcohol)/kaolinite intercalated nanocomposites (Kao-PVA) were prepared via in situ intercalation radical polymerization. Vinyl acetate (VAc) was intercalated into kaolinite by a displacement method using dimethyl sulfoxide/kaolinite (Kao-DMSO) as the intermediate. Then, PVAc/kaolinite (Kao-PVAc) was obtained via radical polymerization with benzoyl peroxide (BPO) as initiator. Last, PVAc/kaolinite was saponified via direct-hydrolysis with NaOH solution in order to obtain PVA/kaolinite nanocomposites, which was characterized by Fourier-Transformation spectroscopy (FTIR), wide X-ray diffraction (WXRD) and transmission electron microscopy (TEM). Their differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) results of the obtained PVA/kaolinite suggested that the thermal properties had an obvious improvement.

  13. Hydrogen ion-selective poly(vinyl chloride) membrane electrode based on a calix[4]arene.

    PubMed

    Kuruoğlu, Demet; Canel, Esin; Memon, Shahabuddin; Yilmaz, Mustafa; Kiliç, Esma

    2003-02-01

    A hydrogen ion-selective poly(vinyl chloride) membrane electrode was constructed using 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetracyanomethoxycalix[4]arene as a neutral carrier. The electrode showed an apparent Nernstian response in the 2-11.5 pH range with a slope of 54.0 +/- 0.2 mV/pH at 20 +/- degrees C. This electrode showed a rapid response of the emf to changes in the pH, high ion selectivity with respect to lithium, sodium and potassium, and characteristics similar to those reported for the conventional pH glass membrane electrode. It can be used as a potentiometric indicator electrode in hydrofluoric acid solutions. The effects of iodide, thiocyanate, perchlorate and bromide on the characteristics of the electrode were also considered.

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

    SciTech Connect

    Lang, K.; Chowdhury, G.; Matsuura, T.; Sourirajan, S. )

    1994-08-01

    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.

  15. Morphological analysis of Polyethersulfone/polyvinyl Acetate blend membrane synthesized at various polymer concentrations

    NASA Astrophysics Data System (ADS)

    Hadi, S. H. A. A.; Mannan, H. A.; Mukhtar, H.; Shaharun, M. S.; Murugesan, T.

    2016-06-01

    This paper reports the effect of varying polymer concentration i.e. solvent/polymer ratio on the morphology and gas transport behaviour of polyethersulfone/polyvinyl acetate blend membrane. The solvent used was dimethylformamide, while the manipulated variable was polymer concentration. The concentrations were varied from 75-90 weight % solvent. A homogeneous surface with dense cross-section structure membranes were successfully developed as deduced from FESEM images. The permeability of CO2 and CH4 gases increased with increasing polymer concentration and an improved CO2/CH4 selectivity was observed. These observation made from the characterization justified the applicability of the blend to be synthesized as membrane for gas separation.

  16. Unusual Morphologies of Poly(vinyl alcohol) Thin Films Adsorbed on Poly(dimethylsiloxane) Substrates.

    PubMed

    Karki, Akchheta; Nguyen, Lien; Sharma, Bhanushee; Yan, Yan; Chen, Wei

    2016-04-05

    Adsorption of poly(vinyl alcohol) (PVOH), 99% and 88% hydrolyzed poly(vinyl acetate), to poly(dimethylsiloxane) (PDMS) substrates was studied. The substrates were prepared by covalently attaching linear PDMS polymers of 2, 9, 17, 49, and 116 kDa onto silicon wafers. As the PDMS molecular weight/thickness increases, the adsorbed PVOH thin films progressively transition from continuous to discontinuous morphologies, including honeycomb and fractal/droplet. The structures are the result of thin film dewetting that occurs upon exposure to air. The PVOH film thickness does not vary significantly on these PDMS substrates, implicating the PDMS thickness as the cause for the morphology differences. The adsorbed PVOH thin films are less stable and have a stronger tendency to dewet on thicker, more liquid-like PDMS layers. When PVOH(99%) and PVOH(88%) thin films are compared, fractal and droplet morphologies are observed on high molecular weight PDMS substrates, respectively. The formation of the unique fractal features in the PVOH(99%) thin films as well as other crystalline and semicrystalline thin films is most likely driven by crystallization during the dehydration process in a diffusion-limited aggregation fashion. The only significant enhancement in hydrophilicity via PVOH adsorption was obtained on PDMS(2k), which is completely covered with a PVOH thin film. To mimic the lower receding contact angle and less liquid-like character of the PDMS(2k) substrate, light plasma treatment of the higher molecular weight PDMS substrates was carried out. On the treated PDMS substrates, the adsorbed PVOH thin films are in the more continuous honeycomb morphology, giving rise to significantly enhanced wettability. Furthermore, hydrophobic recovery of the hydrophilized PDMS substrates was not observed during a 1 week period. Thus, light plasma oxidation and subsequent PVOH adsorption can be utilized as a means to effectively hydrophilize conventional PDMS substrates. This study

  17. Cyto- and genotoxicological assessment and functional characterization of N-vinyl-2-pyrrolidone-acrylic acid-based copolymeric hydrogels with potential for future use in wound healing applications.

    PubMed

    Kirf, Dominik; Higginbotham, Clement L; Rowan, Neil J; Devery, Sinéad M

    2010-06-01

    This study investigated the toxicity of N-vinyl-2-pyrrolidone-acrylic acid copolymer hydrogels crosslinked with ethylene glycol dimethacrylate or poly(ethylene glycol) dimethacrylate. There is a pressing need to establish the toxicity status of these new copolymers because they may find applications in future wound healing processes. Investigations revealed that the capacity of these hydrogels for swelling permitted the retention of high amounts of water yet still maintaining structural integrity. Reverse phase HPLC analysis suggested that unreacted monomeric base material was efficiently removed post-polymerization by applying an additional purification process. Subsequently, in vitro toxicity testing was performed utilizing direct and indirect contact exposure of the polymers to human keratinocytes (HaCaT) and human hepatoma (HepG2) cells. No indication of significant cell death was observed using the established MTT, neutral red (NR) and fluorescence-based toxicity endpoint indicators. In addition, the alkaline Comet assay showed no genotoxic effects following cell exposure to hydrogel extracts. Investigations at the nucleotide level using the Ames mutagenicity assay demonstrated no evidence of mutagenic activity associated with the polymers. Findings from this study demonstrated that these hydrogels are non-cytotoxic and further work can be carried out to investigate their potential as a wound-healing device that will impact positively on patient health and well-being.

  18. A randomised crossover trial comparing a single-use polyvinyl chloride laryngeal mask airway with a single-use silicone laryngeal mask airway.

    PubMed

    Bell, S F; Morris, N G; Rao, A; Wilkes, A R; Goodwin, N

    2012-12-01

    We compared insertion rates of single-use polyvinyl chloride laryngeal mask airways (LMAs) vs single-use silicone LMAs in 72 anaesthetised patients. Both airways were produced by Flexicare Medical. Laryngeal mask airway insertion was successful on the first attempt in 68/72 (94%) polyvinyl chloride LMAs vs 64/72 (89%) silicone LMAs (p = 0.39). Overall insertion rates were 72/72 (100%) for the polyvinyl chloride LMAs and 71/72 (99%) for the silicone LMAs (p = 1.0). Mean (SD) insertion times were similar for polyvinyl chloride and silicone LMAs: 24.3 (5.1)s vs 24.8 (7.8)s (p = 0.64). Laryngeal mask airway position, as assessed using a fibrescope, was not different (p = 0.077). The median (IQR [range]) leak pressure was 16 (12-20 [6-30]) cmH(2) O for the polyvinyl LMA and 18 (13-22 [6-30]) cmH(2) O or the silicone LMA (p = 0.037). In conclusion, we did not find any important differences between polyvinyl chloride and silicone laryngeal mask airways.

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

    PubMed

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

    2014-03-15

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

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

    PubMed

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

    2009-06-01

    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.

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

    SciTech Connect

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

    2003-03-08

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

  2. [Toxicity of chemicals produced by thermal destruction of synthetic materials based on polyvinyl chloride and used in coal mines].

    PubMed

    Bolonova, L N; Sukhanov, V V; Teplova, T E

    1996-01-01

    The experiments on mongrel white rats studied toxicity of the products appearing during thermal destruction of conveyer tape TK-200 based on polyvinyl chloride and used in coal mines. The studies helped to define parameters of acute toxicity and the MACs for products of the conveyer tape burning, considering the main contents and the exposure intensity for 30-120 minutes; to determine jeopardy class; to calculate specific volatilization; to design recommendations for prevention of poisoning during fire in the mines.

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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

  4. Manipulating the morphologies of poly(vinyl alcohol) block copolymer surfactants

    NASA Astrophysics Data System (ADS)

    Repollet-Pedrosa, Milton H.

    Amphiphilic block copolymers (ABCs) are macromolecules containing well-defined hydrophilic and hydrophobic segments that self-assemble into nanoscale aggregates such as spherical and cylindrical micelles and vesicles, when dispersed in block-selective solvents. ABCs possess a miniscule critical micelle concentration, which results in kinetically trapped and persistent assemblies in solution with slow chain exchange between aggregates. This makes them useful as rheological modifiers for personal care products, enhanced oil recovery, and drug delivery formulations. Their utility in many of these applications is crucially dependent on the ability to control the micellar morphologies that they adopt in selective solvents. Triggering ABC micellar morphological transformations, i.e. from spherical to cylindrical micelles, is important for generating "on-demand" stimuli-responsive morphologies that control the aggregate morphology and the bulk solution properties in any given application. In this thesis, we develop the straightforward synthesis of biodegradable and biocompatible ABCs comprised of poly(vinyl acetate) (PVAc) and poly(vinyl alcohol) (PVA), with narrow molecular distributions and variable yet well-defined compositions. These block copolymer amphiphiles readily form spherical micelles in aqueous dispersions. We demonstrate that the addition of a water-soluble poly(ethylene oxide) (PEO) homopolymer to these dispersions results in a rapid transformation of these spherical micelles into cylindrical micelles. Dilution of these cylindrical micelles with water induces their reversion to spherical micelles. Our results indicate that the reversible morphology change depends sensitively on the PEO homopolymer concentration and molecular weight, as well as the length of the PVA corona block of the micelles. Through a series of quantitative 1H NMR studies, we found that the preferential partitioning of PEO homopolymer into the PVAc micellar core drives this morphological

  5. Development of structure in natural silk spinning and poly(vinyl alcohol) hydrogel formation

    NASA Astrophysics Data System (ADS)

    Willcox, Patricia Jeanene

    This research involves the characterization of structure and structure formation in aqueous systems. Particularly, these studies investigate the effect of various processing variables on the structure formation that occurs upon conversion from aqueous solution to fiber or hydrogel. The two processes studied include natural silk fiber spinning and physical gelation of poly(vinyl alcohol), PVOH, in water. The techniques employed combine cryogenic technology for sample preparation and direct observation by transmission electron microscopy with electron diffraction, atomic force microscopy, optical rheometry, X-ray scattering and optical microscopy. In order to explore the full range of structure formation in natural silk spinning, studies are conducted in vivo and in vitro. In vivo structural investigations are accomplished through the cryogenic quenching and subsequent microtoming of live silk-spinning animals, Nephila clavipes (spider) and Bombyx mori (silkworm). Observations made using transmission electron microscopy, electron diffraction and atomic force microscopy indicate a cholesteric liquid crystalline mesophase of aqueous silk fibroin in both species. The mechanism of structure formation in solution is studied in vitro using optical rheometry on aqueous solutions made from regenerated Bombyx mori cocoon silk. Concentrated solutions exhibit birefringence under flow, with a wormlike conformation of the silk molecules in concentrated salt solution. Changes in salt concentration and pH of the aqueous silk solutions result in differing degrees of alignment and aggregation. These results suggest that structural control in the natural silk spinning process is accomplished by chemical manipulation of the electrostatic interactions and hydrogen bonding between chains. Application of cryogenic methods in transmission electron microscopy also provides a unique look at hydration-dependent structures in gels of poly(vinyl alcohol) produced by freeze-thaw processing

  6. Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol).

    PubMed

    Congdon, Thomas R; Notman, Rebecca; Gibson, Matthew I

    2016-09-12

    Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications-from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action.

  7. Enabling thermal processing of ritonavir-polyvinyl alcohol amorphous solid dispersions by KinetiSol® Dispersing.

    PubMed

    LaFountaine, Justin S; Jermain, Scott V; Prasad, Leena Kumari; Brough, Chris; Miller, Dave A; Lubda, Dieter; McGinity, James W; Williams, Robert O

    2016-04-01

    Polyvinyl alcohol has received little attention as a matrix polymer in amorphous solid dispersions (ASDs) due to its thermal and rheological limitations in extrusion processing and limited organic solubility in spray drying applications. Additionally, in extrusion processing, the high temperatures required to process often exclude thermally labile APIs. The purpose of this study was to evaluate the feasibility of processing polyvinyl alcohol amorphous solid dispersions utilizing the model compound ritonavir with KinetiSol® Dispersing (KSD) technology. The effects of KSD rotor speed and ejection temperature on the physicochemical properties of the processed material were evaluated. Powder X-ray diffraction and modulated differential scanning calorimetry were used to confirm amorphous conversion. Liquid chromatography-mass spectroscopy was used to characterize and identify degradation pathways of ritonavir during KSD processing and (13)C nuclear magnetic resonance spectroscopy was used to investigate polymer stability. An optimal range of processing conditions was found that resulted in amorphous product and minimal to no drug and polymer degradation. Drug release of the ASD produced from the optimal processing conditions was evaluated using a non-sink, pH-shift dissolution test. The ability to process amorphous solid dispersions with polyvinyl alcohol as a matrix polymer will enable further investigations of the polymer's performance in amorphous systems for poorly water-soluble compounds.

  8. Biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel for knee meniscus applications, including comparison with human donor samples.

    PubMed

    Hayes, Jennifer C; Curley, Colin; Tierney, Paul; Kennedy, James E

    2016-03-01

    The primary objective of this research was the biomechanical analysis of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous polyvinyl alcohol (PVA) was treated with a sodium sulphate (Na2SO4) solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. The freeze-thaw process, a strictly physical method of crosslinking, was employed to crosslink the hydrogel. Development of a meniscal shaped mould and sample housing unit allowed the production of meniscal shaped hydrogels for direct comparison to human meniscal tissue. Results obtained show that compressive responses were slightly higher in PVA/Na2SO4 menisci, displaying maximum compressive loads of 2472N, 2482N and 2476N for samples having undergone 1, 3 and 5 freeze-thaw cycles respectively. When compared to the human meniscal tissue tested under the same conditions, an average maximum load of 2467.5N was observed. This suggests that the PVA/Na2SO4 menisci are mechanically comparable to the human meniscus. Biocompatibility analysis of PVA/Na2SO4 hydrogels revealed no acute cytotoxicity. The work described herein has innovative potential in load bearing applications, specifically as an alternative to meniscectomy as replacement of critically damaged meniscal tissue in the knee joint where repair is not viable.

  9. Influence of Block Copolymerization on the Antifreeze Protein Mimetic Ice Recrystallization Inhibition Activity of Poly(vinyl alcohol)

    PubMed Central

    2016-01-01

    Antifreeze (glyco) proteins are produced by many cold-acclimatized species to enable them to survive subzero temperatures. These proteins have multiple macroscopic effects on ice crystal growth which makes them appealing for low-temperature applications—from cellular cryopreservation to food storage. Poly(vinyl alcohol) has remarkable ice recrystallization inhibition activity, but its mode of action is uncertain as is the extent at which it can be incorporated into other high-order structures. Here the synthesis and characterization of well-defined block copolymers containing poly(vinyl alcohol) and poly(vinylpyrrolidone) by RAFT/MADIX polymerization is reported, as new antifreeze protein mimetics. The effect of adding a large second hydrophilic block is studied across a range of compositions, and it is found to be a passive component in ice recrystallization inhibition assays, enabling retention of all activity. In the extreme case, a block copolymer with only 10% poly(vinyl alcohol) was found to retain all activity, where statistical copolymers of PVA lose all activity with very minor changes to composition. These findings present a new method to increase the complexity of antifreeze protein mimetic materials, while retaining activity, and also to help understand the underlying mechanisms of action. PMID:27476873

  10. [Characterization of collagen/polyvinyl alcohol complex membrane crosslinked by UV-riboflavin].

    PubMed

    Zhao, Hongbin; Ma, Hui; Zeng, Ping; Lin, Yang; Zhang, Quanwei

    2013-10-01

    The objective of this investigation was to study the characteristics and biocompatibility of collagen/polyvinyl alcohol (PVA) membrane crosslinked by UV-riboflavin. Membranes that were made into complex ones with different mass ratios of collagen to PVA (1:1 and 2:1) were synthesized, and crosslinked with UV-riboflavin. The surface characteristics were analyzed using the omnipotent materials instrument, IR, SEM, water absorption test, gas permeability test, and degradation test, respectively. The biocompatibility of membrane complex and rat bone marrow mesenchymal stem cells (BMSCs) was evaluated after 7 d and 14 d, respectively. The collagen/PVA complex membranes showed good homogeneity, mechanical property, degradation ratio, water absorption, gas permeability, etc. The biocompatibility of the collagen/PVA (2:1) complex membrane crosslinked with UV-Riboflavin was higher than that of without crosslinking and collagen/PVA (1:1) membrane. It could be well concluded that collagen/PVA complex membranes crosslinked with UV-riboflavin would have a potential application in biomedicine.

  11. Recording of diffraction gratings in polyvinyl alcohol/acrylamide photopolymers by pulsed laser irradiation

    NASA Astrophysics Data System (ADS)

    Garcia, Celia; Costela, Angel; Fimia, Antonio; Garcia-Moreno, Inmaculada; Pascual, Inmaculada V.; Sastre, Roberto

    2001-06-01

    In this communication we present the experimental results obtained when diffraction gratings are stored using pulsed exposure in polyvinyl alcohol/acrylamide photopolymer deposited in a dry film. The influence of the energy of the irradiation pulse was studied and the number of pulses needed to reach maximum diffraction efficiency was obtained. The recording was performed using a n holographic copying process. The original patten employed was a gratin of 1000 lines/mm processed according to sliver halide sensitized gelatin, with a beam ratio of 1:2 and transmittance of 75 percent. We exposed the samples by recording holograms with as collimated beam from a frequency-doubled Nd:YAG Q- switched laser. The pulse duration was approximately 8 ns and the frequency of repetition varied between 2 and 10 Hz. The pulse fluence was increased from 0.07 mJ/cm2 to 6.7 mJ/cm2. Our initial results show that it is possible to obtain diffraction gratings with a diffraction efficiency of 60 percent. The energetic sensitivities achieved are close to those obtained when working with the same material and continuous irradiation, without processing of the gratings.

  12. Mucus-penetrating nanoparticles made with "mucoadhesive" poly(vinyl alcohol).

    PubMed

    Popov, Alexey; Enlow, Elizabeth; Bourassa, James; Chen, Hongming

    2016-10-01

    Nanoparticles that readily penetrate mucosal layers are desirable for a variety of biomedical applications. Nevertheless, most nanoparticles tend to be immobilized in mucus via steric and/or adhesive interactions. Contrary to the established opinion that poly(vinyl alcohol) (PVA) is mucoadhesive, we discovered that coating otherwise mucoadhesive nanoparticles with certain partially hydrolyzed PVAs can aid particle mobility in mucus. We describe two approaches to producing such mucus-penetrating particles (non-covalent modification of pre-formed nanoparticles and emulsification in the presence of PVA) and provide mobility data in human cervicovaginal mucus ex vivo as measured by multiple particle tracking and bulk permeation. When coated with PVAs that are ≥95% hydrolyzed, nanoparticles as small as ~210nm were immobilized in mucus similarly to well-established mucoadhesive controls (P>0.05). However, nanoparticles coated with PVAs that are <95% hydrolyzed penetrated mucus with velocities significantly exceeding those for the mucoadhesive controls (P<0.001) and were mobile in the bulk permeation assay.

  13. Acoustic characterization of polyvinyl chloride and self-healing silicone as phantom materials

    NASA Astrophysics Data System (ADS)

    Ceh, Dennis; Peters, Terry M.; Chen, Elvis C. S.

    2015-03-01

    Phantoms are physical constructs used in procedure planning, training, medical imaging research, and machine calibration. Depending on the application, the material a phantom is made out of is very important. With ultrasound imaging, phantom materials used need to have similar acoustic properties, specifically speed of sound and attenuation, as a specified tissue. Phantoms used with needle insertion require a material with a similar tensile strength as tissue and, if possible, the ability to self heal increasing its overall lifespan. Soft polyvinyl chloride (PVC) and silicone were tested as possible needle insertion phantom materials. Acoustic characteristics were determined using a time of flight technique, where a pulse was passed through a sample contained in a water bath. The speed of sound and attenuation were both determined manually and through spectral analysis. Soft PVC was determined to have a speed of sound of approximately 1395 m/s and attenuation of 0.441 dB/cm (at 1 MHz). For the silicone mixture, the respective speed of sound values was within a range of 964.7 m/s and 1250.0 m/s with an attenuation of 0.547 dB/cm (at 1 MHz).

  14. Enlarged-taper tailored Fiber Bragg grating with polyvinyl alcohol coating for humidity sensing

    NASA Astrophysics Data System (ADS)

    Liang, Yanhong; Yan, Guofeng; He, Sailing

    2015-08-01

    In this paper, a novel optical fiber sensor based on an enlarged-taper tailored fiber Bragg grating (FBG) is proposed and experimentally demonstrated for the measurement of relative humidity. The enlarged-taper works as a multifunctional joint that not only excites cladding modes but also recouples the cladding modes reflected by the FBG back into the leading single mode fiber. Due to the fact that cladding modes have a strong evanescent field penetrating into the ambient medium, the intensity of the reflected cladding modes is greatly influenced by the refractive index (RI) of the ambient medium. Polyvinyl alcohol (PVA) film is plated on the fiber surface by dip-coating technique, as a humidity-to-refractive index transducer, whose RI variance from 1.49 to 1.34 when the ambient humidity increases from 20%RH to 95%RH. The relative humidity response of the sensing structure is investigated in our home-made humidity chamber with a commercial hygrometer. By monitoring the intensity of the reflected cladding modes, the RH variance can be demodulated. Experimental results show that RH sensitivity depends on the RH value, and a sensitivity up to 1.2 dB/%RH can be achieved within the RH range of 30-90%. A fast and reversible time response has also been investigated. Such a probe-type and reusable fiber-optic RH sensor is a very promising technology for biochemical sensing applications, e.g., breath analysis, chemical reaction monitoring.

  15. Structure and physical properties of high amorphous polyvinyl alcohol/clay composites

    NASA Astrophysics Data System (ADS)

    Russo, P.; Speranza, V.; Vignali, A.; Tescione, F.; Buonocore, G. G.; Lavorgna, M.

    2015-12-01

    Recently a high amorphous polyvinyl alcohol (HAVOH) which can be easily melt processed has been patented and commercialized with the trade name G-Polymer. In this work, we report on the characterization of clay-G-Polymer composites obtained by melt processing of HAVOH with two commercial chemically-modified organoclays, Cloisite 15A and Cloisite 30B. Results show that the extent of polymer intercalation in the layered clay structure as well as the thermal and mechanical properties of the obtained composites depend on the nature of clay organo-modifier, i.e a quaternary ammonium salt of dimethyl dehydrogenated tallow for Cloisite 15A and an alkyl ammonium salt of bis-(2-hydroxyethyl)methyl tallow for Cloisite 30B. In particular Cloisite 15A, which is only slightly intercalated by the polymer during melt compounding, contributes to enhance glass transition temperature and mechanical properties of the resulting composites. On the contrary, Cloisite 30B which is significantly intercalated by the interacting polymer macromolecules, disturbs to some extent the H-bonding network established within the polymeric matrix thus showing a reduction of thermal and mechanical properties.

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

    SciTech Connect

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

    2000-05-01

    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.

  17. Adsorption of Methylene Blue from Aqueous Solutions by Polyvinyl Alcohol/Graphene Oxide Composites.

    PubMed

    Yang, Xiaoxia; Li, Yanhui; Du, Qiuju; Wang, Xiaohui; Hu, Song; Chen, Long; Wang, Zonghua; Xia, Yanzhi; Xia, Linhua

    2016-02-01

    As a new member of the carbon family, graphene oxide (GO) has shown excellent adsorption ability to micro-pollutants in aqueous solutions. However, its tiny size makes it difficult to be removed from aqueous solutions using the conventional separation methods, which limits its practical application in the environmental protection. In this study, polyvinyl alcohol (PVA) was used as carrier immobilizing GO, and novel PVA/GO composites were prepared. The morphology and physicochemical properties of the composites were characterized by SEM, FTIR and TGA analysis. The adsorption properties of methylene blue (MB) onto the composites were studied through investigating the experimental parameters such as solution pH, adsorbent dosage, contact time and temperature. The isotherm data were analyzed using the Langmuir, Freundlich and Dubinin-Radushkevich models. The calculated maximum adsorption capacity reached 476.2 mg/g at 50% GO content. The pseudo-first-order kinetic, pseudo-second-order kinetic and intra-particle diffusion models were used to explore the adsorption kinetics. The results showed that the dynamic data were fitted to the pseudo-second-order kinetic model.

  18. TiO2 and polyvinyl alcohol (PVA) coated polyester filter in bioreactor for wastewater treatment.

    PubMed

    Liu, Lifen; Zhao, Chuanqi; Yang, Fenglin

    2012-04-15

    Prepared by coating TiO(2)/polyvinyl alcohol (PVA) on a low cost polyester filter cloth (22 μm), a composite membrane (10 μm pore size) was successfully used in an anoxic/oxic membrane bioreactor (A/O-MBR) for treating a simulate wastewater in removing nitrate/ammonium for water reuse in a polyester fiber production plant. Its permeate flux and the anti-fouling properties against extracellular polymeric substances (EPS) were studied. Comparing with a commercial (0.1 μm) PVDF (polyvinylidene fluoride) membrane, similar effluent qualities were achieved, meeting the basic COD requirements for reuse. Anti-EPS accumulation, the TiO(2)/PVA Polyester composite membrane had higher sustained permeability and required less frequent cleaning. Its filtration time was 4 times longer when operated at a higher flux than the PVDF membrane. The nano-TiO(2) enhances the interaction between PVA and polyester, forms a more hydrophilic surface, drastically reduces the contact angle with water and reduces EPS fouling. The slow (trans-membrane pressure) TMP rise, loose cake layer, the low filtration resistances, and the EPS, SEM analysis confirmed the advantage of the composite membrane. Potential in lowering the membrane cost, the operation and maintenance cost, and in enhancing MBR waste water treatment efficiency is expected by the use of this new composite membrane.

  19. Poly(vinyl alcohol)-coated microfluidic devices for high-performance microchip electrophoresis.

    PubMed

    Belder, Detlev; Deege, Alfred; Kohler, Frank; Ludwig, Martin

    2002-10-01

    The channels of microfluidic glass chips have been coated with poly(vinyl alcohol) (PVA). Applied for microchip electrophoresis, the coated devices exhibited a suppressed electroosmotic flow and improved separation performance. The superior performance of PVA-coated channels could be demonstrated by electrophoretic separations of labeled amines and by video microscopy. While a distorted sample zone is injected using uncoated channels the application of PVA-coated channels results in an improved shape of the sample zone with less band broadening. Applying PVA-coated microchips for the separation of amines labeled with Alexa Fluor 350 even sub-second separations, utilizing a separation length of only 650 microm, could be obtained, while this was not possible using uncoated devices. By using PVA-coated devices rather than an uncoated chip a threefold increase in separation efficiencies could be observed. As the electroosmotic flow (EOF) was suppressed, the anionic compounds were detected at the anode whereas the dominant EOF in uncoated devices resulted in an effective mobility to the cathode. Besides improved separation performance another important feature of the PVA-coated channels was the suppressed adsorption of fluorescent compounds in repetitive runs which results in an improved robustness and detection sensitivity. Applying PVA-coated channels, rinsing or etching steps could be omitted while this was necessary for a reliable operation of uncoated devices.

  20. White organic light-emitting diodes based on electroplex from polyvinyl carbazole and carbazole oligomers blends

    NASA Astrophysics Data System (ADS)

    Chen, Fei-Peng; Xu, Bin; Zhao, Zu-Jin; Tian, Wen-Jing; Lü, Ping; Im, Chan

    2010-03-01

    White organic light-emitting diodes with a blue emitting material fluorene-centred ethylene-liked carbazole oligomer (Cz6F) doped into polyvinyl carbazole (PVK) as the single light-emitting layer are reported. The optical properties of Cz6F, PVK, and PVK:Cz6F blends are studied. Single and double layer devices are fabricated by using PVK: Cz6F blends, and the device with the configuration of indium tin oxide (ITO)/PVK:Cz6F/tris(8-hydroxyquinolinate)aluminium (Alq3)/LiF/A1 exhibits white light emission with Commission Internationale de l'Éclairage chromaticity coordinates of (0.30, 0.33) and a brightness of 402 cd/m2. The investigation reveals that the white light is composed of a blue-green emission originating from the excimer of Cz6F molecules and a red emission from an electroplex from the PVK:Cz6F blend films.

  1. Adsorption properties of polyvinyl-alcohol-grafted particles toward genistein driven by hydrogen-bond interaction.

    PubMed

    Zhang, Yanyan; Gao, Baojiao; Xu, Zeqing

    2013-05-09

    The adsorption properties of polyvinyl alcohol (PVA)-grafted silica gel particles PVA/SiO2 toward genistein are researched in this paper. The effects of the main factors on the adsorption properties are investigated, the adsorption mechanism is explored in depth, and the adsorption thermodynamics is researched. The experimental results show that the conventional hydrogen bond is formed between the hydroxyl groups with high density on the surfaces of PVA/SiO2 and the phenolic hydroxyl groups in genistein, while π-type hydrogen bond is formed between the hydroxyl groups of PVA/SiO2 and the conjugated aromatic rings. It is the two types of hydrogen bond that make the functional composite particles PVA/SiO2 produce very strong physical adsorption toward genistein. The competitive adsorption of the solvent can have severe negative impact on the adsorption capacity of genistein. Increasing temperature will weaken the hydrogen-bond interaction between PVA/SiO2 particles and genistein. The existence of electrolytes in the protic solvent will affect the adsorption negatively. The adsorption process of PVA/SiO2 particles toward genistein is exothermic and driven by enthalpy. The adsorption isotherm data matches the Langmuir model.

  2. Synthesis of magnetic and multiferroic materials from polyvinyl alcohol-based gels

    NASA Astrophysics Data System (ADS)

    Lisnevskaya, I. V.; Bobrova, I. A.; Lupeiko, T. G.

    2016-01-01

    This review article summarizes results on the synthesis of the magnetic materials including modified nickel ferrite (Ni0.9Co0.1Cu0.1Fe1.9O4-δ), yttrium iron garnet (Y3Fe5O12), lanthanum-containing manganites (MxLa1-xMnO3 (M=Pb, Ba or Sr; x=0.3-0.35)), and multiferroics (BiFeO3 and BiFe0.5Mn0.5O3) from polyvinyl alcohol-based gels. It is shown that the ammonium nitrate accelerates destruction of organic components of xerogels and thus Ni0.9Co0.1Cu0.1Fe1.9O4-δ and BiFeO3 can be prepared at record low temperatures (100 and 250 °C, respectively) which are 200-300 °C lower compared to the process where air is used as an oxidizing agent. As for the synthesis of Y3Fe5O12, MxLa1-xMnO3 and BiFe0.5Mn0.5O3, the presence of NH4NO3 favors formation of foreign phases, which ultimately complicate reaction mechanisms and lead to the higher temperature to synthesize target products. Developed methods provide nanoscale magnetic and multiferroic materials with an average particle size of ∼20-50 nm.

  3. Conductive, tough, hydrophilic poly(vinyl alcohol)/graphene hybrid fibers for wearable supercapacitors

    NASA Astrophysics Data System (ADS)

    Chen, Shaohua; Ma, Wujun; Xiang, Hengxue; Cheng, Yanhua; Yang, Shengyuan; Weng, Wei; Zhu, Meifang

    2016-07-01

    Graphene fibers based flexible supercapacitors have great potential as wearable power sources for textile electronics. However, their electrochemical performance is limited by the serious stacking of graphene sheets and their hydrophobicity in aqueous electrolytes. Meanwhile, their brittleness is unfavorable for practical application. Incorporation of nanofillers into graphene fibers has been proved effective for enhancing their capacitance, whereas often leading to deteriorated mechanical strength. Herein we demonstrate that the strength, toughness and capacitive performance of graphene-based fibers can be significantly enhanced simultaneously, simply by incorporating hydrophilic poly(vinyl alcohol) (PVA) into a non-liquid-crystalline graphene oxide (GO) dispersion before wet spinning and chemical reduction. The structure and properties of the resulted PVA/graphene hybrid fibers are systematically investigated, and the mechanism behind these enhancements is discussed in detail. The hybrid fiber with a PVA/GO weight ratio of 10/90 possesses a strength of 186 MPa, a toughness of 11.3 J cm-3, and a capacitance of 241 F cm-3 in 1 M H2SO4. A solid-state yarn supercapacitor assembled from these fibers exhibits a device energy of 5.97 mW h cm-3, and features excellent flexibility and bending stability. This device is robust enough to be integrated into textile and thus promising as wearable power supply for smart textiles.

  4. Melt-processed poly(vinyl alcohol) composites filled with microcrystalline cellulose from waste cotton fabrics.

    PubMed

    Sun, Xunwen; Lu, Canhui; Liu, Yong; Zhang, Wei; Zhang, Xinxing

    2014-01-30

    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.

  5. Lipase immobilization on epoxy-activated poly(vinyl acetate-acrylamide) microspheres.

    PubMed

    Zhang, Dong-Hao; Peng, Li-Juan; Wang, Yun; Li, Ya-Qiong

    2015-05-01

    Poly(vinyl acetate-acrylamide) microspheres with an average diameter of 2-4μm were successfully prepared and characterized via SEM and FTIR. Then the microspheres were modified with epoxy groups through reacting with epichlorohydrin and used as carriers to covalently immobilize Candida rugosa lipase. The results revealed that agitation played an important role on epoxy activation and the immobilization ratio increased with the increase of the epoxy density. On the other hand, the specific activity of the immobilized lipase as well as the activity recovery declined gradually with the increase in the immobilization ratio from 72% to 93%, which were attributed to the steric hindrance effects caused by enzyme overloading. When epoxy density was 76μmol/g microsphere, the activity recovery reached the maximum at 47.5%, and the activity of the immobilized lipase was 261.3U/g microsphere. Moreover, the thermal stability of the immobilized lipase was much better than that of the free one, which indicated potential applications of the immobilized lipase.

  6. Improvement of Starch Digestion Using α-Amylase Entrapped in Pectin-Polyvinyl Alcohol Blend

    PubMed Central

    Cruz, Maurício; Fernandes, Kátia; Cysneiros, Cristine; Nassar, Reginaldo; Caramori, Samantha

    2015-01-01

    Polyvinyl alcohol (PVA) and pectin blends were used to entrap α-amylase (Termamyl) using glutaraldehyde as a cross-linker. The effect of glutaraldehyde concentration (0.25, 0.5, 0.75, 1.0, and 1.25%) on the activity of the immobilized enzyme and rate of enzyme released was tested during a 24 h period. Characteristics of the material, such as scanning electron microscopy (SEM), tensile strength (TS), elongation, and rate of dissolution in water (pH 5.7), ruminal buffering solution (pH 7.0), and reactor containing 0.1 mol L−1 sodium phosphate buffer (pH 6.5), were also analyzed. SEM results showed that the surfaces of the pectin/PVA/amylase films were highly irregular and rough. TS values increased as a function of glutaraldehyde concentration, whereas percentage of elongation (%E) decreased. Pectin/PVA/amylase films presented similar values of solubility in the tested solvents. The material obtained with 0.25% glutaraldehyde performed best with repeated use (active for 24 h), in a phosphate buffer reactor. By contrast, the material obtained with 1.25% glutaraldehyde presented higher performance during in vitro testing using an artificial rumen. The results suggest that pectin/PVA/amylase is a highly promising material for biotechnological applications. PMID:25949991

  7. Coupled electron beam radiation and MBR treatment of textile wastewater containing polyvinyl alcohol.

    PubMed

    Sun, Weihua; Chen, Jun; Chen, Lujun; Wang, Jianlong; Zhang, Yongming

    2016-07-01

    Advanced oxidation processes (AOP) can be combined with biological treatments for recalcitrant organic pollutant decomposition. However, there has been no thorough investigation on the coupling of AOPs and membrane bioreactors (MBR) to treat polymer organic pollutants. This study proposes a new AOP that couples electron beam (EB) radiation and MBR treatment. This method was applied to treat real textile effluents containing polyvinyl alcohol (PVA). During the stable operation stage, 31 ± 7% (n = 28) COD was removed by the EB-MBR process. COD removal was enhanced to 45% at the end of the research period without process optimization. In addition, both the membrane flux and activated sludge system exhibited good stability. Only a 2% membrane flux decreased was observed after a 46 d operation period. PVA radiolysis and biofacies analysis mechanisms are also discussed. By contrast, PVA degradation using only the MBR treatment was ineffective in this study. This ineffectiveness was caused by membrane interception and floccule formation by PVA and activated sludge.

  8. In-Line Ultrasonic Monitoring for Sediments Stuck on Inner Wall of a Polyvinyl Chloride Pipe

    PubMed Central

    2014-01-01

    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

  9. Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite.

    PubMed

    Moreau, David; Villain, Arthur; Ku, David N; Corté, Laurent

    2014-01-01

    Insufficient bone anchoring is a major limitation of artificial substitutes for connective osteoarticular tissues. The use of coatings containing osseoconductive ceramic particles is one of the actively explored strategies to improve osseointegration and strengthen the bone-implant interface for general tissue engineering. Our hypothesis is that hydroxyapatite (HA) particles can be coated robustly on specific assemblies of PVA hydrogel fibers for the potential anchoring of ligament replacements. A simple dip-coating method is described to produce composite coatings made of microscopic hydroxyapatite (HA) particles dispersed in a poly(vinyl alcohol) (PVA) matrix. The materials are compatible with the requirements for implant Good Manufacturing Practices. They are applied to coat bundles of PVA hydrogel fibers used for the development of ligament implants. By means of optical and electronic microscopy, we show that the coating thickness and surface state can be adjusted by varying the composition of the dipping solution. Quantitative analysis based on backscattered electron microscopy show that the exposure of HA at the coating surface can be tuned from 0 to over 55% by decreasing the weight ratio of PVA over HA from 0.4 to 0.1. Abrasion experiments simulating bone-implant contact illustrate how the coating cohesion and wear resistance increase by increasing the content of PVA relative to HA. Using pullout experiments, we find that these coatings adhere well to the fiber bundles and detach by propagation of a crack inside the coating. These results provide a guide to select coated implants for anchoring artificial ligaments.

  10. Electrospun polylactic acid and polyvinyl alcohol fibers as efficient and stable nanomaterials for immobilization of lipases.

    PubMed

    Sóti, Péter Lajos; Weiser, Diana; Vigh, Tamás; Nagy, Zsombor Kristóf; Poppe, László; Marosi, György

    2016-03-01

    Electrospinning was applied to create easy-to-handle and high-surface-area membranes from continuous nanofibers of polyvinyl alcohol (PVA) or polylactic acid (PLA). Lipase PS from Burkholderia cepacia and Lipase B from Candida antarctica (CaLB) could be immobilized effectively by adsorption onto the fibrous material as well as by entrapment within the electrospun nanofibers. The biocatalytic performance of the resulting membrane biocatalysts was evaluated in the kinetic resolution of racemic 1-phenylethanol (rac-1) and 1-phenylethyl acetate (rac-2). Fine dispersion of the enzymes in the polymer matrix and large surface area of the nanofibers resulted in an enormous increase in the activity of the membrane biocatalyst compared to the non-immobilized crude powder forms of the lipases. PLA as fiber-forming polymer for lipase immobilization performed better than PVA in all aspects. Recycling studies with the various forms of electrospun membrane biocatalysts in ten cycles of the acylation and hydrolysis reactions indicated excellent stability of this forms of immobilized lipases. PLA-entrapped lipases could preserve lipase activity and enantiomer selectivity much better than the PVA-entrapped forms. The electrospun membrane forms of CaLB showed high mechanical stability in the repeated acylations and hydrolyses than commercial forms of CaLB immobilized on polyacrylamide beads (Novozyme 435 and IMMCALB-T2-150).

  11. Polyethylene glycol-polyvinyl alcohol grafted copolymer: study of the bioavailability after oral administration to rats.

    PubMed

    Heuschmid, Franziska F; Schuster, Paul; Lauer, Birthe; Fabian, Eric; Leibold, Edgar; van Ravenzwaay, Bennard

    2013-07-01

    The absorption, urinary excretion, and the biliary excretion of a single oral dose of 10 or 1000 mg/kg bw of (14)C-polyethylene glycol-polyvinyl alcohol (PEG-PVA) grafted copolymer were studied in adult male and female rats. In a balance/excretion experiment, the total excretion of ingested radioactivity was determined over a period of 168 h and residual radioactivity was detected in selected tissues and the carcass. In a biliary excretion experiment, excretion of radioactivity via the bile duct was determined over a period of 48 h after administration of the substance to cannulated rats. Most, if not all, of the radioactivity (>100%) was excreted within 48 h via the feces regardless of sex or dose. Urinary excretion was very limited: 0.45-0.50% of dose at the low dose and 0.22-0.27% of dose at the high dose. At both dose levels, residual radioactivity in the carcass and all organs and tissues after 168 h was ≤ 0.02% of dose. Biliary excretion was 0.01-0.02% of dose. Based on these findings, the bioavailability of PEG-PVA grafted copolymer was determined to be <1% demonstrating that absorption was virtually negligible following a single oral administration to male and female rats.

  12. Developmental toxicity of polyethylene glycol-g-polyvinyl alcohol grafted copolymer in rats and rabbits.

    PubMed

    Heuschmid, Franziska F; Schneider, Steffen; Schuster, Paul; Lauer, Birthe; van Ravenzwaay, Bennard

    2013-07-01

    Polyethylene glycol-g-polyvinyl alcohol (PEG-PVA) grafted copolymer was evaluated in developmental toxicity studies with Wistar rats and Himalayan rabbits. Pregnant Wistar rats were gavaged with 0 (vehicle control), 100, 300, or 1000 mg PEG-PVA grafted copolymer/kg bw/day from gestation day (GD) 6-15. Pregnant Himalayan rabbits received the same treatment from GD 6 to 19. On GD 20 and 29 for rats and rabbits, respectively, the animals were euthanized and were examined grossly. For each dam, corpora lutea were counted and number and distribution of implantation sites were determined. The fetuses were removed, sexed, weighed, and evaluated for any external, soft tissue, and skeletal findings. No significant findings were found that could be attributed to administration of PEG-PVA grafted copolymer. Under the conditions of these studies, the no-observed-adverse-effect level (NOAEL) for maternal and developmental toxicity in both species was the highest dose tested of 1000 mg/kg bw/day.

  13. Polyethylene glycol-g-polyvinyl alcohol grafted copolymer: reproductive toxicity study in Wistar rats.

    PubMed

    Heuschmid, Franziska F; Schneider, Steffen; Schuster, Paul; Lauer, Birthe; van Ravenzwaay, Bennard

    2013-07-01

    Polyethylene glycol-g-polyvinyl alcohol (PEG-PVA) grafted copolymer was administered by gavage to groups of 25 male and 25 female young Wistar rats at doses of 0 (vehicle control), 100, 300, or 1000 mg/kg bw/day for one generation (F0). The study followed the treated F0 generation through mating, gestation, lactation, and weaning of the F1 generation. F1 animals were mated and followed to gestation day (GD) 15-17 at which time F2 implants were evaluated. There were no indications from the various clinical and gross pathological examinations that the oral administration of PEG-PVA grafted copolymer to the F0-parental rats produced any signs of general, reproductive, or developmental toxicity in the F0 or F1 animals or F2 implants. Based on the lack of any dose-related or biologically relevant effects on fertility, reproduction, development, and overall health of rats gavaged with PEG-PVA grafted copolymer and their progeny, the no-observed-adverse effect level (NOAEL) was determined to be the highest dose tested of 1000 mg/kg bw/day.

  14. Subchronic toxicity of polyethylene glycol-g-polyvinyl alcohol grafted copolymer.

    PubMed

    Heuschmid, Franziska F; Schuster, Paul; Lauer, Birthe; Buesen, Roland; Mellert, Werner; Groeters, Sibylle; van Ravenzwaay, Bennard

    2013-07-01

    The safety of polyethylene glycol-g-polyvinyl alcohol (PEG-PVA) grafted copolymer was evaluated in a 13-week oral toxicity study in rats and in a 9-month oral toxicity study in dogs. Wistar rats were administered 600, 3000, or 15,000 ppm PEG-PVA grafted copolymer in their drinking water whereas beagle dogs were fed 3000, 10,000, or 30,000 ppm PEG-PVA grafted copolymer in the diet. There were no mortalities, no adverse clinical signs, no toxicologically adverse effects on body weight or body weight gain, feed consumption, hematological, clinical chemistry or urinary parameters, or histopathology in either species. In rats, no treatment-related effects were observed in the functional observational battery (FOB) or related measurements of motor activity. Increased water consumption observed in rats at the highest dose was the only test substance-induced effect noted. The no-observed-adverse-effect level (NOAEL) was the highest concentration tested in both species: 15,000 ppm in rats (corresponding to a daily intake of 1611 mg/kg bw for males and 2191 mg/kg bw for females) and 30,000 ppm in dogs (corresponding to a mean daily intake of 783 mg/kg bw for males and 811 mg/kg bw for females).

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

    SciTech Connect

    Lai, J.Y.; Chen, R.Y.; Lee, K.R

    1993-05-01

    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.

  16. Permanent hydrophilic modification of polypropylene and poly(vinyl alcohol) films by vacuum ultraviolet radiation

    NASA Astrophysics Data System (ADS)

    Belmonte, Guilherme Kretzmann; Charles, German; Strumia, Miriam Cristina; Weibel, Daniel Eduardo

    2016-09-01

    Polypropylene (PP) and Poly(vinyl alcohol) (PVA) both synthetics polymers but one of them biodegradable, were surface modified by vacuum ultraviolet (VUV) irradiation. After VUV irradiation in an inert nitrogen atmosphere, the films were exposed to oxygen gas. The treated films were characterized by water contact angle measurements (WCA), optical profilometry, FTIR-ATR, XPS, UPS and NEXAFS techniques. PP and PVA VUV-treated films reached superhydrophilic conditions (WCAs <10°) in about 30 min of irradiation under our experimental conditions. It was observed that when the WCAs reached about 35-40° the hydrophilicity was permanent in both polymers. These results contrasted with typical plasma treatments were a rapid hydrophobic recovery with aging time is usually observed. UPS and XPS data showed the presence of new functionalities on the PP and PVA surfaces that were assigned to COO, Cdbnd O, Csbnd O and Cdbnd C functional groups. Finally, grafting of styrene (ST) as a typical monomer was tested on PP films. It was confirmed that only in the VUV irradiated region an efficient grafting of ST or polymerized ST was found. Outside the irradiated regions no ST grafted was observed. Our results showed the potential use of VUV treatment for surface modification and processing of polymers which lack chromophores in the UV region.

  17. Poly(vinyl alcohol)-Tannic Acid Hydrogels with Excellent Mechanical Properties and Shape Memory Behaviors.

    PubMed

    Chen, Ya-Nan; Peng, Lufang; Liu, Tianqi; Wang, Yaxin; Shi, Shengjie; Wang, Huiliang

    2016-10-12

    Shape memory hydrogels have promising applications in a wide variety of fields. Here we report the facile fabrication of a novel type of shape memory hydrogels physically cross-linked with both stronger and weaker hydrogen bonding (H-bonding). Strong multiple H-bonding formed between poly(vinyl alcohol) (PVA) and tannic acid (TA) leads to their coagulation when they are physically mixed at an elevated temperature and easy gelation at room temperature. The amorphous structure and strong H-bonding endow the PVA-TA hydrogels with excellent mechanical properties, as indicated by their high tensile strengths (up to 2.88 MPa) and high elongations (up to 1100%). The stronger H-bonding between PVA and TA functions as the "permanent" cross-link and the weaker H-bonding between PVA chains as the "temporary" cross-link. The reversible breakage and formation of the weaker H-bonding imparts the PVA-TA hydrogels with excellent temperature-responsive shape memory. Wet and dried hydrogel samples with a deformed or elongated shape can recover to their original shapes when immersed in 60 °C water in a few seconds or at 125 °C in about 2.5 min, respectively.

  18. Fabrication and mechanical characterization of a polyvinyl alcohol sponge for tissue engineering applications.

    PubMed

    Karimi, A; Navidbakhsh, M; Faghihi, S

    2014-05-01

    Polyvinyl alcohol (PVA) sponges are widely used for clinical applications, including ophthalmic surgical treatments, wound healing and tissue engineering. There is, however, a lack of sufficient data on the mechanical properties of PVA sponges. In this study, a biomechanical method is used to characterize the elastic modulus, maximum stress and strain as well as the swelling ratio of a fabricated PVA sponge (P-sponge) and it is compared with two commercially available PVA sponges (CENEFOM and EYETEC). The results indicate that the elastic modulus of the P-sponge is 5.32% and 13.45% lower than that of the CENEFOM and EYETEC sponges, while it bears 4.11% more and 10.37% less stress compared to the CENEFOM and EYETEC sponges, respectively. The P-sponge shows a maximum strain of 32% more than the EYETEC sponge as well as a 26.78% higher swelling ratio, which is a significantly higher absorbency compared to the CENEFOM. It is believed that the results of this study would help for a better understanding of the extension, rupture and swelling mechanism of PVA sponges, which could lead to crucial improvement in the design and application of PVA-based materials in ophthalmic and plastic surgeries as well as wound healing and tissue engineering.

  19. Dual functions of polyvinyl alcohol (PVA): fabricating particles and electrospinning nanofibers applied in controlled drug release

    NASA Astrophysics Data System (ADS)

    Qin, Xiao-Hong; Wu, De-Qun; Chu, Chih-Chang

    2013-01-01

    The fabrication of submicron size microsphere from 8-Phe-4 poly(ester amide) (PEA) using polyvinyl alcohol (PVA) as the emulsion was reported. The biodegradable microspheres were prepared by an oil-in-water emulsion/solvent evaporation technique, and PVA was used as the emulsion. Furthermore, the emulsion PVA was electrospun into nanofibrous mats, and 8-Phe-4 PEA microspheres were entrapped in the resultant mats. The dual functions of PVA to fabricate ideal nanofibrous mats which can entrap microspheres in them and to obtain 8-Phe-4 microspheres as emulsion in their potential application were demonstrated. The anti-cancer drug doxorubicin (DOX) was encapsulated in the 8-Phe-4 amino acid-based PEA microspheres and the entrapment efficiency is almost 100 %. At the same time, the DOX can be controlled released in PBS solution and in α-chymotrypsin solution. The cytotoxicity of PVA, PVA mats-entrapped 8-Phe-4 microspheres and PVA mats-entrapped DOX-loaded 8-Phe-4 microspheres, was investigated. Hela cells were used to test the cytotoxicity of the DOX that released from the PVA mats-entrapped DOX-loaded 8-Phe-4 microspheres for 2 days, and the cell viability is below 30 % when the 8-Phe-4 microspheres concentration is 1 mg/mL. It demonstrated that the PVA mats-entrapped DOX-loaded 8-Phe-4 microspheres have a potential biomedical application.

  20. FAS Grafted Electrospun Poly(vinyl alcohol) Nanofiber Membranes with Robust Superhydrophobicity for Membrane Distillation.

    PubMed

    Dong, Zhe-Qin; Wang, Bao-Juan; Ma, Xiao-hua; Wei, Yong-Ming; Xu, Zhen-Liang

    2015-10-14

    This study develops a novel type of electrospun nanofiber membranes (ENMs) with high permeability and robust superhydrophobicity for membrane distillation (MD) process by mimicking the unique unitary microstructures of ramee leaves. The superhydrophobic ENMs were fabricated by the eletrospinning of poly(vinyl alcohol) (PVA), followed by chemical cross-linking with glutaraldehyde and surface modification via low surface energy fluoroalkylsilane (FAS). The resultant FAS grafted PVA (F-PVA) nanofiber membranes were endowed with self-cleaning properties with water contact angles of 158° and sliding angles of 4° via the modification process, while retaining their high porosities and interconnected open structures. For the first time, the robust superhydrophobicity of the ENMs for MD was confirmed by testing the F-PVA nanofiber membranes under violent ultrasonic treatment and harsh chemical conditions. Furthermore, vacuum membrane distillation experiments illustrated that the F-PVA membranes presented a high and stable permeate flux of 25.2 kg/m2 h, 70% higher than those of the commercial PTFE membranes, with satisfied permeate conductivity (<5 μm/cm) during a continuous test of 16 h (3.5 wt % NaCl as the feed solution, and feed temperature and permeate pressure were set as 333 K and 9 kPa, respectively), suggesting their great potentials in myriad MD processes such as high salinity water desalination and volatile organiccompounds removal.

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

    PubMed

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

    2014-01-01

    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.

  2. Case report of occupational asthma induced by polyvinyl chloride and nickel.

    PubMed

    Song, Ga-Won; Ban, Ga-Young; Nam, Young-Hee; Park, Hae-Sim; Ye, Young-Min

    2013-10-01

    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.

  3. In vitro model of bacterial biofilm formation on polyvinyl chloride biomaterial.

    PubMed

    Zhao, Guang-qiang; Ye, Lian-hua; Huang, Yun-chao; Yang, Da-kuan; Li, Li; Xu, Geng; Lei, Yu-jie

    2011-11-01

    The aim of the study was to establish an in vitro model of Staphylococcus epidermidis biofilms on polyvinyl chloride (PVC) material, and to investigate bacterial biofilm formation and its structure using the combined approach of confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM). Staphylococcus epidermidis bacteria (stain RP62A) were incubated with PVC pieces in Tris buffered saline to form biofilms. Biofilm formation was examined at 6, 12, 18, 24, 30, and 48 h. Thicknesses of these biofilms and the number, and percentage of viable cells in biofilms were measured. CT scan images of biofilms were obtained using CLSM and environmental SEM. The results of this study showed that Staphylococcus epidermidis biofilm is a highly organized multi-cellular structure. The biofilm is constituted of large number of viable and dead bacterial cells. Bacterial biofilm formation on the surface of PVC material was found to be a dynamic process with maximal thickness being attained at 12-18 h. These biofilms became mature by 24 h. There was significant difference in the percentage of viable cells along with interior, middle, and outer layers of biofilms (P < 0.05). Staphylococcus epidermidis biofilm is sophisticated in structure and the combination method involving CLSM and SEM was ideal for investigation of biofilms on PVC material.

  4. Cell adhesive and antifouling polyvinyl chloride surfaces via wet chemical modification.

    PubMed

    Gabriel, Matthias; Strand, Dennis; Vahl, Christian-Friedrich

    2012-09-01

    Polyvinyl chloride (PVC) is one of the most frequently used polymers for the manufacturing of medical devices. Limitations for its usage are based upon unfavorable surface properties of the polymer including its hydrophobicity and lack of functionalities in order to increase its versatility. To address this issue, wet chemical modification of PVC was performed through surface amination using the bifunctional compound ethylene diamine. The reaction was conducted in order to achieve maximum surface amination while leaving the bulk material unaffected. The initial activation step was characterized by means of various methods including contact angle measurements, colorimetric amine quantification, infrared spectroscopy, and gel permeation chromatography. Depth profiles were obtained by a confocal microscopic method using fluorescence labeling. Exclusive surface modification was thus confirmed. To demonstrate biological applications of the presented technique, two examples were chosen: The covalent immobilization of the cell adhesive Asp-Gly-Asp-Ser-peptide (RGD) onto PVC samples yielded a surface that strongly supported cellular adhesion and proliferation of fibroblasts. In contrast, the decoration of PVC with the hydrophilic polymer polyethylene glycol prevented cellular adhesion to a large extent. The impact of these modifications was demonstrated by cell culture experiments.

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

    NASA Astrophysics Data System (ADS)

    Hanafy, Taha A.

    2012-08-01

    Fourier transform infrared (FTIR) spectrum dielectric constant, ɛ', loss tangent, tan(δ), electric modulus, M*, and ac conductivity, σac, 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, ρ and α 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, α-relaxation process splits into αa and αc. This splitting is due to the segmental motion in the amorphous (αa) and crystalline (αc) 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.

  6. Heterogeneous structure of poly(vinyl chloride) as the origin of anomalous dynamical behavior

    NASA Astrophysics Data System (ADS)

    Arbe, A.; Moral, A.; Alegria, A.; Colmenero, J.; Pyckhout-Hintzen, W.; Richter, D.; Farago, B.; Frick, B.

    2002-07-01

    We have investigated the thermal evolution of the structure and the dynamics of poly(vinyl chloride) (PVC) in a wide temperature range. Corroborating earlier findings, small angle neutron scattering revealed the presence of structural heterogeneities. On the other hand, the single chain form factor corresponds to that of Gaussian chains. Gradually with increasing temperature the system becomes homogeneous. A simple description of the heterogeneities in terms of microcrystallites is forwarded. The dynamical behavior of PVC has been investigated combining broadband dielectric spectroscopy (DS) with coherent and incoherent neutron scattering. In a wide temperature range broadband DS facilitated a precise determination of the dynamic response related to the segmental relaxation. Close to the glass transition temperature the line shape strongly deviates from the usual Kohlrausch-Williams-Watts functional form of common glassforming systems. Moreover, the characteristic relaxation time observed by incoherent scattering displays an anomalous dependence on momentum transfer indicating the possible existence of heterogeneities in the sample. Based on the structural and dynamical results, a model is proposed, that considers the coexistence of regions with different dynamical properties leading to a distribution of characteristic relaxation times. The model accounts for the experimental observations, assuming for all regions the same functional form for the alpha-relaxation. It may be univocally determined from the coherent scattering data at the first static structure peak. The distribution of relaxation times found is compatible with the distribution of only one variable, the glass transition temperature.

  7. Characterization methods for radiation crosslinked poly(vinyl methyl ether) hydrogels

    NASA Astrophysics Data System (ADS)

    Schmidt, Thomas; Querner, Claudia; Arndt, Karl-Friedrich

    2003-08-01

    The paper reviews recent results of radiation crosslinking of poly(vinyl methyl ether) (PVME). It will give an overview of possible characterization methods for both, soluble and crosslinked PVME. The irradiation of aqueous low concentrated PVME solutions with γ-rays of low doses results in structural changes of PVME molecules. We are able to monitor changes in the chemical structure by spectroscopic methods (IR, NMR) as well as the changes of molecular parameters (e.g. molecular weight, molecular weight distribution, branches) by classical methods for polymer characterization (size exclusion chromatography with diverse detector systems, SLS, viscosimetry). The characterization of the network parameters (crosslinking density νc, molecular weight of the network chains Mc) of PVME bulkgels crosslinked by irradiation at high dose values by classical methods (swelling and compression measurements) provides incorrect results because of the high porosity of the gels. PVME microgel particles can be prepared by irradiation of a phase separated diluted aqueous PVME solution above their lower critical solution temperature. These microgels with decreased dimensions were characterized by SLS, DLS and field emission scanning electron microscopy.

  8. Radiation crosslinking and scission parameters for poly(vinyl methyl ether) in aqueous solution

    NASA Astrophysics Data System (ADS)

    Janik, I.; Kasprzak, E.; Al-Zier, A.; Rosiak, J. M.

    2003-08-01

    In oxygen-free aqueous solutions, poly(vinyl methyl ether) (PVME) was subjected to gamma irradiation. In such conditions PVME radicals recombine by way of crosslinking. The major result of crosslinking is an increase in the average molecular weight of the polymer, which close to the gelation point tends to infinity. Further irradiation increases the amount of formed gel, while the soluble fraction - sol decreases. The basic parameters related to the radiation processing are gelation dose - Dg, as well as radiation yield of intermolecular crosslinking and scission, GX and GS, respectively. There are three general approaches for estimation of those parameters. The first method is based on the study of molecular weight changes before the gelation point. The second method combines the gel-sol as well as the swelling analysis results. The third one allows one to calculate the yield of crosslinking from the value of Dg. All of these methods of calculation were used in this work for determination of radiation parameters and results obtained are discussed.

  9. Sensitivity and Response of Polyvinyl Alcohol/Tin Oxide Nanocomposite Multilayer Thin Film Sensors.

    PubMed

    Sriram, G; Dhineshbabu, N R; Nithyavathy, N; Saminathan, K; Kaler, K V I S; Rajendran, V

    2016-01-01

    Nanocrystalline Tin Oxide (SnO₂) is Non-Stoichiometric in Nature with Functional Properties Suitable for gas sensing. In this study, SnO₂nanoparticles were prepared by the sol-gel technique, which were then characterised using X-ray diffraction. The nanoparticles showed tetragonal structure with an average crystallite size of 18 nm. The stretching and vibration modes of SnO₂were confirmed using Fourier transform infrared spectroscopy. The size of SnO₂ nanoparticles was determined using particle size analyser, which was found be 60 ± 10 nm on average. The surface morphology of the nanoparticles was investigated using scanning electron microscope, which showed irregular-sized agglomerated SnO₂nanostructures. In addition, primary particle size was evaluated using high-resolution transmission electron microscopy, which was found to be 50 nm on average. The polyvinyl alcohol/SnO₂ composite thin film was prepared on a glass substrate using spin-coating method. The values of band gap energy and electrical conductance of 13-layer thin film were found to be 2.96 eV and 0.0505 mho, respectively. Sulfur dioxide (SO₂) was suitably tailored to verify the sensor response over a concentration range of 10-70 ppm at room temperature. The performance, response, and recovery time of sensors were increased by increasing the layers of the thin film.

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

    PubMed

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

    2015-01-22

    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 143.42 g g(-1) in distilled water and a water absorbency of 39.75 g g(-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.

  11. Gamma irradiation induced in situ synthesis of lead sulfide nanoparticles in poly(vinyl alcohol) hydrogel

    NASA Astrophysics Data System (ADS)

    Kuljanin-Jakovljević, Jadranka Ž.; Radosavljević, Aleksandra N.; Spasojević, Jelena P.; Carević, Milica V.; Mitrić, Miodrag N.; Kačarević-Popović, Zorica M.

    2017-01-01

    In this study, the nanocomposites based on semiconductor lead sulfide (PbS) nanoparticles and poly(vinyl alcohol) (PVA) were investigated. The gamma irradiation induced in situ incorporation of PbS nanoparticles in crosslinked polymer network i.e. PVA hydrogel was performed. PVA hydrogel was previously obtained also under the influence of gamma irradiation. UV-Vis absorption and X-ray diffraction measurements were employed to investigate optical and structural properties of PbS nanoparticles, respectively, and obtained results indicates the presence of nanoparticles with approximately 6 nm in diameter and face centered cubic rock-salt crystal structure. The porous morphology was confirmed by scanning electron microscopy. Swelling data revealed that investigated hydrogels (PVA and PbS-PVA nanocomposite) shows non-Fickian diffusion, indicating that both diffusion and polymer relaxation processes controlled the fluid transport. The values of diffusion coefficients have an order of magnitude 10-9 cm2/s (typical values for water diffusion in polymers) and the best fit with the experimental results showed the Etters approximation. Comparing the thermal properties of PbS-PVA xerogel nanocomposite with PVA xerogel it was observed that incorporation of PbS nanoparticles in crosslinked PVA matrix just slightly enhanced the thermal stability of nanocomposite.

  12. Improvement of starch digestion using α-amylase entrapped in pectin-polyvinyl alcohol blend.

    PubMed

    Cruz, Maurício; Fernandes, Kátia; Cysneiros, Cristine; Nassar, Reginaldo; Caramori, Samantha

    2015-01-01

    Polyvinyl alcohol (PVA) and pectin blends were used to entrap α-amylase (Termamyl) using glutaraldehyde as a cross-linker. The effect of glutaraldehyde concentration (0.25, 0.5, 0.75, 1.0, and 1.25%) on the activity of the immobilized enzyme and rate of enzyme released was tested during a 24 h period. Characteristics of the material, such as scanning electron microscopy (SEM), tensile strength (TS), elongation, and rate of dissolution in water (pH 5.7), ruminal buffering solution (pH 7.0), and reactor containing 0.1 mol L(-1) sodium phosphate buffer (pH 6.5), were also analyzed. SEM results showed that the surfaces of the pectin/PVA/amylase films were highly irregular and rough. TS values increased as a function of glutaraldehyde concentration, whereas percentage of elongation (%E) decreased. Pectin/PVA/amylase films presented similar values of solubility in the tested solvents. The material obtained with 0.25% glutaraldehyde performed best with repeated use (active for 24 h), in a phosphate buffer reactor. By contrast, the material obtained with 1.25% glutaraldehyde presented higher performance during in vitro testing using an artificial rumen. The results suggest that pectin/PVA/amylase is a highly promising material for biotechnological applications.

  13. Poly(vinyl alcohol)/sodium alginate/layered silicate based nanofibrous mats for bacterial inhibition.

    PubMed

    Li, Wei; Li, Xueyong; Chen, Yang; Li, Xiaoxia; Deng, Hongbing; Wang, Ting; Huang, Rong; Fan, Gang

    2013-02-15

    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.

  14. Controlled release of retinyl acetate from β-cyclodextrin functionalized poly(vinyl alcohol) electrospun nanofibers.

    PubMed

    Lemma, Solomon M; Scampicchio, Matteo; Mahon, Peter J; Sbarski, Igor; Wang, James; Kingshott, Peter

    2015-04-08

    Retinyl acetate (RA) was effectively incorporated into electrospun nanofibers of poly(vinyl alcohol) (PVA) containing β-cyclodextrin (β-CD) in order to form inclusion complexes for encapsulation to prolong shelf life and thermal stability. The physical and thermal properties of encapsulated RA were determined by scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The nanofibers of PVA/RA and PVA/RA/β-CD exhibited bead free average fiber diameters of 264 ± 61 and 223 ± 49 nm, respectively. The surface chemistry of the functional nanofibers was investigated by X-ray photoelectron spectroscopy (XPS). Thermogravimetric analysis (TGA) demonstrated different thermal stabilities between the bioactive and the polymer, with and without β-CD. Square-wave voltammogram peak current changes were used to follow the release kinetics of RA from the nanofibers. Results indicate that RA coated inside PVA/β-CD nanofibers was protected against oxidation much better than RA in PVA nanofibers and should extend the shelf life. In addition, RA encapsulated in the PVA/β-CD had better thermal stability than PVA nanofibers.

  15. Polyaniline coated cellulose fiber / polyvinyl alcohol composites with high dielectric permittivity and low percolation threshold

    NASA Astrophysics Data System (ADS)

    Anju, V. P.; Narayanankutty, Sunil K.

    2016-01-01

    Cost effective, high performance dielectric composites based on polyvinyl alcohol, cellulose fibers and polyaniline were prepared and the dielectric properties were studied as a function of fiber content, fiber dimensions and polyaniline content over a frequency range of 40 Hz to 30 MHz. The short cellulose fibers were size-reduced to micro and nano levels prior to coating with polyaniline. Fiber surface was coated with Polyaniline (PANI) by an in situ polymerization technique in aqueous medium. The composites were then prepared by solution casting method. Short cellulose fiber composites showed a dielectric constant (DEC) of 2.3 x 105 at 40 Hz. For the micro- and nano- cellulose fiber composites the DEC was increased to 4.5 x 105 and 1.3 x 108, respectively. To gain insight into the inflection point of the dielectric data polynomial regression analysis was carried out. The loss tangent of all the composites remained at less than 1.5. Further, AC conductivity, real and imaginary electric moduli of all the composites were evaluated. PVA nanocomposite attained an AC conductivity of 3 S/m. These showed that by controlling the size of the fiber used, it was possible to tune the permittivity and dielectric loss to desired values over a wide range. These novel nanocomposites, combining high dielectric constant and low dielectric loss, can be effectively used in applications such as high-charge storage capacitors.

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

    PubMed

    Sun, Xiaoxia; Uyama, Hiroshi

    2013-10-04

    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.

  17. Rhizobia survival in seeds coated with polyvinyl alcohol (PVA) electrospun nanofibres.

    PubMed

    Damasceno, Raquel; Roggia, Isabel; Pereira, Claudio; de Sá, Enilson

    2013-11-01

    The electrospinning technique of rhizobia immobilization in nanofibres is an innovative and promising alternative for reducing the harmful effects of environmental stress on bacteria strains in a possible inoculant nanotechnology product for use in agriculture. The use of polyvinyl alcohol (PVA) shows up as an effective polymer in cell encapsulation because of its physical characteristics, such as viscosity and power of scattering. The aim of these studies has been to evaluate the survival of rhizobia incorporated in PVA nanofibres, which were applied to soybean seed and then subjected to different storage times and exposure to fungicide. The maintenance of the symbiotic characteristics of the incorporated bacterial strains was also evaluated, noting the formation of nodules in the soybean seedlings. No significant differences in the cell survival at 0 h and after 24 h of storage were observed. After 48 h, a significant difference in the bacterial cell concentration of the seeds affixed with PVA nanofibres was observed. Exposure to the fungicide decreased the viability of the bacteria strains even when coated with the nanofibres. A larger number of nodules formed in soybean seedlings from seeds inoculated with rhizobia incorporated in PVA nanofibres than from seeds inoculated with rhizobia without PVA. Thus, the electrospinning technique is a great alternative to the usual protector inoculants because of its unprecedented capacity to control the release of bacteria.

  18. A visco-hyperelastic constitutive approach for modeling polyvinyl alcohol sponge.

    PubMed

    Karimi, Alireza; Navidbakhsh, Mahdi; Beigzadeh, Borhan

    2014-02-01

    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.

  19. Estimated risks of water and saliva contamination by phthalate diffusion from plasticized polyvinyl chloride.

    PubMed

    Corea-Téllez, Kira S; Bustamante-Montes, Patricia; García-Fábila, Magdalena; Hernández-Valero, María A; Vázquez-Moreno, Flavio

    2008-10-01

    Phthalates are additives commonly used to convert hard polyvinyl chloride (PVC) resins into flexible and workable plastics employed in the production of chewable rubber toys and other soft-plastic products. In theory, phthalates can diffuse in small quantities to the surface of a product, and from there they can enter the environment and the human body. The purpose of this study was to determine the diffusion of phthalates from plasticized PVC in water and artificial saliva; to determine the migration of di(2-ethylhexyl) (DEHP) phthalate in human saliva using gas chromatography; to compare the experimental values with theoretical values calculated using a model based on the principles of molecular diffusion in fluids; and to use the experimental values to estimate daily doses of DEHP received by Mexican children and infants using plastic and soft-plastic products (e.g., pacifiers, chewable toys, and bottles). Our findings indicated phthalate diffusion of 0.36 microg/cm2 per hour and 4.10 microg/cm2 per hour, respectively, in water and artificial saliva. The average value of phthalate diffusion in vivo was 6.04 microg/cm2 per hour. The daily oral phthalate exposure in Mexican infants and toddlers from oral use of rubber toys and soft-plastic products is 18.12 microg/kg. These daily doses are considerably lower than the maximum daily phthalate intake recommended by an international public health committee.

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

    PubMed

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

    2014-12-01

    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.

  1. Electrospinning of porphyrin/polyvinyl alcohol (PVA) nanofibers and their acid vapor sensing capability.

    PubMed

    Jang, Kihun; Baek, Il Woong; Back, Sung Yul; Ahn, Heejoon

    2011-07-01

    Fluorescing 5,10,15,20-terakis(1-methyl-4-pyridinio)porphyrin tetra(p-toluenesulfonate) (TMPyP)-embedded and -coated polyvinyl alcohol (PVA) nanofibers were fabricated by using the electrospinning technique. To improve nonpolar solvent solubility of TMPyP/PVA nanofibers, tetraethyl orthosilicate (TEOS) was used as a cross-linking agent. UV-vis spectroscopy showed a strong Q band and two relatively weak Soret bands from the TMPyP/PVA nanofibers, and revealed that the TMPyP molecules were homogeneously loaded to the fibers. Scanning electron microscopy revealed that the electrospun nanofibers had ultrafine structures with an average diameter of ca. 250 nm. X-ray photoelectron spectroscopy confirmed the compositional structure of TMPyP/PVA/TEOS nanofibers and revealed the relative coverage of TMPyP molecules on the surface of TMPyP-embedded and TMPyP-coated PVA/TEOS fibers. For the comparison of the acid vapor sensitivity, TMPyP-embedded PVA/TEOS films, and TMPyP-embedded PVA/TEOS fibers, TMPyP-coated PVA/TEOS fibers were exposed to 1N nitric-acid vapor for 20-60 seconds. Fluorescence microscopy revealed that TMPyP-coated PVA/TEOS nanofibers exhibited better acid-sensing capability than TMPyP-embedded PVA/TEOS nanofibers and films.

  2. Effect of nanosilica on optical, electric modulus and AC conductivity of polyvinyl alcohol/polyaniline films

    NASA Astrophysics Data System (ADS)

    El-Sayed, Somyia; Abel-Baset, Tarob; Elfadl, Azza Abou; Hassen, Arafa

    2015-05-01

    Nanosilica (NS) was synthesized by a sol-gel method and mixed with 0.98 polyvinyl alcohol (PVA)/0.02 polyaniline (PANI) in different amounts to produce nanocomposite films. High-resolution transmission electron microscopy (HR-TEM) revealed the average particle size of the NS to be ca. 15 nm. Scanning electron microscopy (SEM) showed that the NS was well-dispersed on the surface of the PVA/PNAI films. The Fourier transform infrared (FTIR) spectra of the samples showed a significant change in the intensity of the characteristic peak of the functional groups in the composite films with the amount of NS added. The absorbance and refractive index (n) of the composites were studied in the UV-vis range, and the optical energy band gap, Eg, and different optical parameters were calculated. The dielectric loss modulus, M″ and ac conductivity, σac, of the samples were studied within 300-425 K and 0.1 kHz-5 MHz, respectively. Two relaxation peaks were observed in the frequency dependence of the dielectric loss modulus, M″. The behavior of σac(f) for the composite films indicated that the conduction mechanism was correlated barrier hopping (CBH). The results of this work are discussed and compared with those of previous studies of similar composites.

  3. Controlled chemical stabilization of polyvinyl precursor fiber, and high strength carbon fiber produced therefrom

    DOEpatents

    Naskar, Amit K.

    2016-12-27

    Method for the preparation of carbon fiber, which comprises: (i) immersing functionalized polyvinyl precursor fiber into a liquid solution having a boiling point of at least 60.degree. C.; (ii) heating the liquid solution to a first temperature of at least 25.degree. C. at which the functionalized precursor fiber engages in an elimination-addition equilibrium while a tension of at least 0.1 MPa is applied to the fiber; (iii) gradually raising the first temperature to a final temperature that is at least 20.degree. C. above the first temperature and up to the boiling point of the liquid solution for sufficient time to convert the functionalized precursor fiber to a pre-carbonized fiber; and (iv) subjecting the pre-carbonized fiber produced according to step (iii) to high temperature carbonization conditions to produce the final carbon fiber. Articles and devices containing the fibers, including woven and non-woven mats or paper forms of the fibers, are also described.

  4. Leaching of lead from new unplasticized polyvinyl chloride (uPVC) pipes into drinking water.

    PubMed

    Zhang, Yuanyuan; Lin, Yi-Pin

    2015-06-01

    Unplasticized polyvinyl chloride (uPVC) pipes have been used in the premise plumbing system due to their high strength, long-term durability, and low cost. uPVC pipes, however, may contain lead due to the use of lead compounds as the stabilizer during the manufacturing process. The release of lead from three locally purchased uPVC pipes was investigated in this study. The effects of various water quality parameters including pH value, temperature, and type of disinfectant on the rate of lead release were examined. The elemental mapping obtained using scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) confirmed the presence of lead on the inner surfaces of the uPVC pipes and their surface lead weight percentages were determined. The leachable lead concentration for each pipe was determined using high strength acidic EDTA solutions (pH 4, EDTA = 100 mg/L). Lead leaching experiments using tap water and reconstituted tape water under static conditions showed that the rate of lead release increased with the decreasing pH value and increasing temperature. In the presence of monochloramine, lead release was faster than that in the presence of free chlorine.

  5. Photochromic properties of the molecule Azure A chloride in polyvinyl alcohol matrix

    NASA Astrophysics Data System (ADS)

    Shahab, Siyamak; Filippovich, Liudmila; Kumar, Rakesh; Darroudi, Mahdieh; Borzehandani, Mostafa Yousefzadeh; Gomar, Maryam; Hajikolaee, Fatemeh Haji

    2015-12-01

    In the present work, isomerization, photophysical properties and heat conductivity of the substance Azure A chloride (AZAC): 3-amino-7-(dimethlamino)phenothiazin-5-ium chloride under the action of UV radiation in the presence of polyvinyl alcohol (PVA) matrix was studied using the Hartree-Fock (HF) and Density Functional Theory (DFT) methods. The electronic absorption spectra of AZAC in dimethylformamide (DMF) solution and in aqueous medium before and after UV radiation were calculated. The nature of absorption bands of AZAC and its tautomeric prototropic form with the transfer of the electron (AZAC1) in the visible and near UV spectral regions was interpreted. The solvent effect on the absorption spectrum of the AZAC has established. The comparison of measured FTIR, UV-Visible data allowed assignments of major special features of title molecules. The frontier molecular orbital HOMO-LUMO have been also presented that shows the charge transfer interactions taking place within these molecules. The excitation energies for both molecules AZAC and AZAC1 have also been calculated. The experimental as well as theoretical investigations of azure molecule have a close agreement and it gives other important clues about the properties of the system. Anisotropy of thermal conductivity in PVA-films containing AZAC and AZAC1 were also measured.

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

    PubMed

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

    2014-01-01

    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.

  7. Plasticized poly(vinyl chloride)-based photonic crystal for ion sensing.

    PubMed

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

    2014-12-16

    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 μm-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.

  8. Studies on structural, optical and cluster size of poly(m-toluidine)-polyvinyl chloride blends

    NASA Astrophysics Data System (ADS)

    Lakshmi, G. B. V. S.; Ali, Vazid; Siddiqui, Azher M.; Kulriya, Pawan K.; Zulfequar, M.

    Poly(m-toluidine) (PmT), a derivative of polyaniline, has been prepared by chemical oxidation polymerization method. The synthesized PmT powder is blended with plasticized polyvinyl chloride (PVC) to achieve 20 μm thick self-supported films. These films were irradiated with 60 MeV Si5+ ions at three different fluences whose Se (electronic energy loss) value is found to be 1.988×103 KeV/μ m, an order of magnitude larger than 60 MeV C5+ (2.958×102 KeV/μ m). Fourier transform infrared (FTIR), X-ray diffraction (XRD) and ultraviolet-visible (UV) absorption studies of pre- and post-irradiated films of PmT-PVC blends were carried out to study the heavy ion irradiation effects on these polymer blends. An overall change in the structure of the polymer blend has been observed from FTIR studies. UV-visible spectra show a decrease in the optical band gap (Eg) and an increase in cluster size with increasing fluence. An effort is made to compare these results with our earlier studies. We found that the variation in Se plays an important role in the structural and optical properties of PmT-PVC blends.

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

    PubMed

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

    2015-02-14

    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.

  10. Physical and chemical basics of modification of poly(vinyl chloride) by means of polyisocyanate

    NASA Astrophysics Data System (ADS)

    Islamov, Anvar; Fakhrutdinova, Venera; Abdrakhmanova, Lyailya

    2016-01-01

    This research presents data relating to polyvinyl chloride (PVC) modification by means of reactive oligomer and measures technological, physical and mechanical properties of the modified composites. Polyisocyanate (PIC) has been chosen as the modifying reactive oligomer. It has been shown that insertion of the oligomer has a double effect on PVC. Primarily, PIC produces a plasticizing effect on PVC and in particular leads to an increase in thermal stability and melt flow index at the stage of processing. In addition, the molded PVC composites possess higher strength properties and lower deformability when exposed to temperature because of chemical transformations of PIC in polymer matrix and, as the result, the formation of cross-linked systems takes place. In this case, semi-interpenetrating structures are formed based on cross-linked products of PIC chemical transformations homogeneously distributed in the PVC matrix. It has been determined by means of IR-spectroscopy that the basic products of PIC curing are compounds with urea and biuret groups which leads to modifying effect on PVC especially: increase in strength, thermal and mechanical properties, and chemical resistance.

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

    NASA Astrophysics Data System (ADS)

    Kobayashi, Takuji; Kono, Akiteru; Futagawa, Masato; Sawada, Kazuaki; Tero, Ryugo

    2014-02-01

    We prepared an artificial lipid bilayer on a plasticized poly(vinyl chloride) (PVC) membrane on a Si3N4 layer deposited on a Si wafer. We optimized the experimental condition for the fabrication of the PVC membrane, and obtained a PVC membrane with a flat and uniform surface on the scale of several hundreds of micrometer suitable for a substrate for supported lipid bilayers (SLBs). The SLB of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) was formed on the PVC membrane by the vesicle fusion method. The observation with a conventional epi-fluorescence microscope and a confocal laser scanning microscope gave geometrically uniform images of the SLB on the PVC membrane. The fluidity and the mobile fraction of the SLB was evaluated by the fluorescence recovery after photobleaching method, and compared with that on a thermally oxidized SiO2/Si substrate. The SLB on the PVC membrane contained immobile fraction ˜30%, but the diffusion in the mobile fraction was two times faster than that in the SLB on SiO2/Si, which had little immobile fraction.

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

    NASA Astrophysics Data System (ADS)

    Beshir, W. B.

    2013-05-01

    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 2σ) associated with measurement of response (ΔA mm-1) at 623 nm for dose range 1-8 kGy is 4.53%.

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

    SciTech Connect

    Laurent, Alexandre; Wassef, Michel; Namur, Julien; Ghegediban, Homayra; Pelage, Jean-Pierre

    2010-10-15

    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.

  14. Expression and fermentation optimization of oxidized polyvinyl alcohol hydrolase in E. coli.

    PubMed

    Yang, Yu; Zhang, Dongxu; Liu, Song; Jia, Dongxu; Du, Guocheng; Chen, Jian

    2012-01-01

    Oxidized polyvinyl alcohol (PVA) hydrolase (OPH) is a key enzyme in the degradation of PVA, suggesting that OPH has a great potential for application in textile desizing processes. In this study, the OPH gene from Sphingopyxis sp. 113P3 was modified, by artificial synthesis, for overexpression in Escherichia coli. The OPH gene, lacking the sequence encoding the original signal peptide, was inserted into pET-20b (+) expression vector, which was then used to transform E. coli BL21 (DE3). OPH expression was detected in culture medium in which the transformed E. coli BL21 (DE3) was grown. Nutritional and environmental conditions were investigated for improved production of OPH protein by the recombinant strain. The highest OPH activity measured was 47.54 U/mL and was reached after 84 h under optimal fermentation conditions; this level is 2.64-fold higher that obtained under sub-optimal conditions. The productivity of recombinant OPH reached 565.95 U/L/h. The effect of glycine on the secretion of recombinant OPH was examined by adding glycine to the culture medium to a final concentration of 200 mM. This concentration of glycine reduced the fermentation time by 24 h and increased the productivity of recombinant OPH to 733.17 U/L/h. Our results suggest that the recombinant strain reported here has great potential for use in industrial applications.

  15. Experimental studies on elastic cooling and pyromagnetic effect of polyvinyl chloride sheets with defects

    NASA Astrophysics Data System (ADS)

    Luo, Yingshe; Chen, Shengming; Zhang, Liang; Su, Jianxin; Zhang, Yongzhong; Luo, Shuling

    2012-09-01

    Polyvinyl Chloride (PVC) sheets were made into samples with precast defects for uniaxial tensile test. The tests are carried out under room temperature with conditions of same displacement rate but different defect sizes or of same defect but different displacement rates. The local nonuniform temperature field on whole deformation area of specimen is recorded with a thermal infrared imager and the whole coupling magnetic field with thermal changes in experiments is detected and measured by a self-developed sensors system. The experimental results show that, in a complete tensile test process of PVC samples, the temperature reduction phenomenon emerges firstly in its elastic deformation stage (areas) that temperature of specimen is cooler than room temperature. And then in viscoplastic deformation period (areas), the temperature increases sharply to be obviously higher than room temperature due to the thermo-mechanical coupling effection of tensile load and viscoplastic deformation heat. These thermal variations lead a coupling pyromagnetic effect occur and the effect intensity is dependent strongly on the strain rate and/or the size of defects. The temperature prejudgment conditions for materials yield are preliminary discussed based on this effect.

  16. Performance enhancement of polyvinyl chloride ultrafiltration membrane modified with graphene oxide.

    PubMed

    Zhao, Yuanyuan; Lu, Jiaqi; Liu, Xuyang; Wang, Yudan; Lin, Jiuyang; Peng, Na; Li, Jingchun; Zhao, Fangbo

    2016-10-15

    A novel polyvinyl chloride (PVC) membrane was modified with graphene oxide (GO) via phase inversion method to improve its hydrophilicity and mechanical properties. The GO presented a large amount of hydrophilic groups after the modification through the modified Hummers method. It was observed that with the addition of low fraction of GO powder, the GO/PVC hybrid membranes exhibited a significant enhancement in hydrophilicity, water flux, and mechanical properties. With optimal dosage (0.1wt%), the pure water flux of GO/PVC membrane increased from 232.6L/(m(2)hbar) to 430.0L/(m(2)hbar) and the tensile strength increased from 231.3cN to 305.3cN. The improved properties of the PVC/GO hybrid membranes are mainly attributed to the strong hydrophilicity of functional groups on the GO surface, indicating that GO has a promising candidate for modification of PVC ultrafiltration membranes in wastewater treatment.

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

    PubMed

    Lakshmi, S; Jayakrishnan, A

    2003-04-15

    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.

  18. Microporous polyvinyl chloride: novel reactor for PVC/CaCO3 nanocomposites

    NASA Astrophysics Data System (ADS)

    Xiong, Chuanxi; Lu, Shengjun; Wang, Dongyan; Dong, Lijie; Jiang, David D.; Wang, Qinggang

    2005-09-01

    Microporous polyvinyl chloride (PVC) with pore size of 0.2-2 µm has been obtained by the foaming of PVC powders using a solution of 2,2'-azo-bis-iso-butyronitrile in a co-solvent of butanone and cyclohexanone. The PVC/CaCO3 hybrid powders deposited with CaCO3 nanoparticles have been synthesized using the microporous PVC as reactors of CaCO3 nanoparticles, i.e., the reaction of Ca(OH)2 with CO2 occurs inside the pore of microporous PVC. The in situ PVC/CaCO3 nanocomposites have been prepared by melt blending in situ PVC/CaCO3 hybrid powders. The images of SEM and TEM show that the in situ CaCO3 nanoparticles are uniformly dispersed in the PVC matrix and the sizes of the CaCO3 nanoparticles are less than 50 nm. TEM images and XRD patterns for the in situ CaCO3 strongly suggest that pseudo-amorphous crystals and defect-rich crystals are formed. The mechanical properties and DMA data indicate that the in situ PVC/CaCO3 nanocomposites exhibit much higher strength, toughness, modulus and glass temperature than common PVC/CaCO3 nanocomposites. This novel nanotechnology has potential applications in preparation of organic-inorganic hybrid nanocomposites.

  19. Characterization of poly(vinyl chloride) aged in a bromine containing electrolyte

    SciTech Connect

    Arnold, C. Jr.; Leo, A.; Tarjani, M.

    1988-01-01

    Poly(vinyl chloride) (PVC) is being considered for use as a flow frame material in a developmental zinc/bromine battery. The choice of PVC was based on its low cost and the ease with which it can be molded into complex parts. The electrolyte used in this battery is a highly corrosive mixture of bromine, zinc bromide, zinc chloride, potassium bromide, potassium chloride and a quaternary amine salt. The quaternary salt serves to reduce the concentration of free bromine in the electrolyte by virtue of its complexing capability. It is well known that aqueous bromine is capable of oxidizing organic compounds. The purpose of the current study was to investigate the effect of a bromine electrolyte on two PVC formulations, PVC-1 and PVC-4. PVC-1 is the designation given to one of B.F. Goodrich's commercial formulations and is the present baseline material for the flow frame. PVC-4 is an experimental B.F. Goodrich formulation that was developed especially for battery applications. We sought answers to such questions as (1) does oxidation and/or bromination take place. (2) does bromine penetrate into the sample and, if so, how far. (3) how are the mechanical and morphological properties affected. and (4) are there differences in stability between PVC-1 and PVC-4. To accelerate the aging processes we aged the PVC samples at an elevated temperature in an electrolyte which did not contain any complexing agent. 5 refs., 6 figs.

  20. Comparison of quantification methods illustrates reduced Pseudomonas aeruginosa activity on nanorough polyvinyl chloride.

    PubMed

    Seil, Justin T; Rubien, Nathan M; Webster, Thomas J; Tarquinio, Keiko M

    2011-07-01

    Patients on mechanical ventilators for extended periods of time are faced with a high probability of developing ventilator associated pneumonia. Although this has been mostly addressed through the re-engineering of endotracheal tubes (ETTs) with antimicrobial materials, such material coatings may easily delaminate during use. However, the potential exists to apply nanotechnology to the ETT to avoid delamination but implement antibacterial properties. Selecting a protocol to evaluate in vitro material for anti-infection is difficult, partially due to the existence of conflicting reported methods of analysis. In this study, the susceptibility of conventional and nanorough polymeric materials to bacterial biofilm growth were evaluated. After creating nanorough polyvinyl chloride (PVC) ETTs, Pseudomonas aeruginosa biofilms were then grown on sample surfaces during a 24-h culture. Biofilms were then removed and assayed from sample surfaces using a variety of techniques. Comparisons between the different techniques used for biofilm removal indicated that vortexing provided adequate removal of the biofilm from sample surfaces. Most importantly, a protocol following the vortexing method of biofilm and bacteria removal provided an ∼40% lower yield of colony forming units from nanorough PVC compared to conventional PVC. This suggests that Pseudomonas aeruginosa are less adherent on nanorough PVC than conventional PVC.

  1. Poly(vinyl alcohol) physical hydrogels: noncryogenic stabilization allows nano- and microscale materials design.

    PubMed

    Jensen, Bettina E B; Smith, Anton A A; Fejerskov, Betina; Postma, Almar; Senn, Philipp; Reimhult, Erik; Pla-Roca, Mateu; Isa, Lucio; Sutherland, Duncan S; Städler, Brigitte; Zelikin, Alexander N

    2011-08-16

    Physical hydrogels based on poly(vinyl alcohol), PVA, have an excellent safety profile and a successful history of biomedical applications. However, highly inhomogeneous and macroporous internal organization of these hydrogels as well as scant opportunities in bioconjugation with PVA have largely ruled out micro- and nanoscale control and precision in materials design and their use in (nano)biomedicine. To address these shortcomings, herein we report on the assembly of PVA physical hydrogels via "salting-out", a noncryogenic method. To facilitate sample visualization and analysis, we employ surface-adhered structured hydrogels created via microtransfer molding. The developed approach allows us to assemble physical hydrogels with dimensions across the length scales, from ∼100 nm to hundreds of micrometers and centimeter sized structures. We determine the effect of the PVA molecular weight, concentration, and "salting out" times on the hydrogel properties, i.e., stability in PBS, swelling, and Young's modulus using exemplary microstructures. We further report on RAFT-synthesized PVA and the functionalization of polymer terminal groups with RITC, a model fluorescent low molecular weight cargo. This conjugated PVA-RITC was then loaded into the PVA hydrogels and the cargo concentration was successfully varied across at least 3 orders of magnitude. The reported design of PVA physical hydrogels delivers methods of production of functionalized hydrogel materials toward diverse applications, specifically surface mediated drug delivery.

  2. Recycling of waste automotive laminated glass and valorization of polyvinyl butyral through mechanochemical separation.

    PubMed

    Swain, Basudev; Ryang Park, Jae; Yoon Shin, Dong; Park, Kyung-Soo; Hwan Hong, Myung; Gi Lee, Chan

    2015-10-01

    Due to strong binding, optical clarity, adhesion to many surfaces, toughness and flexibility polyvinyl butyral (PVB) resin films are commonly used in the automotive and architectural application as a protective interlayer in the laminated glass. Worldwide million tons of PVB waste generated from end-of-life automotive associated with various environmental issues. Stringent environmental directive, higher land cost eliminates land filling option, needs a study, we have developed a mechanochemical separation process to separate PVB resins from glass and characterized the separated PVB through various techniques, i.e., scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), infrared spectroscopy (IR) and nuclear magnetic resonance spectroscopy (NMR). Commercial nonionic surfactants D201 used for the mechanochemical separation purpose. Through parameter optimization following conditions are considered to be the optimum condition; 30v ol% D201, stirring speed of 400 rpm, 35 °C temperature, operation time 1h, and dilute D201 volume to waste automotive laminated glass weight ratio of ≈25. The technology developed in our laboratory is sustainable, environmentally friendly, techno-economical feasible process, capable of mass production (recycling).

  3. Flotation separation of polyvinyl chloride and polyethylene terephthalate plastics combined with surface modification for recycling.

    PubMed

    Wang, Chongqing; Wang, Hui; Fu, Jiangang; Zhang, Lingling; Luo, Chengcheng; Liu, Younian

    2015-11-01

    Surface modification with potassium permanganate (KMnO4) solution was developed for separation of polyvinyl chloride (PVC) and polyethylene terephthalate (PET) waste plastics. The floatability of PVC decreases with increasing of KMnO4 concentration, treatment time, temperature and stirring rate, while that of PET is unaffected. Fourier transform infrared (FT-IR) analysis confirms that mechanism of surface modification may be due to oxidization reactions occurred on PVC surface. The optimum conditions are KMnO4 concentration 1.25 mM/L, treatment time 50 min, temperature 60°C, stirring rate 300 r/min, frother concentration 17.5 g/L and flotation time 1 min. PVC and PET with different particle sizes were separated efficiently through two-stage flotation. Additionally, after ultrasonic assisted surface modification, separation of PVC and PET with different mass ratios was obtained efficiently through one-stage flotation. The purity and the recovery of the obtained products after flotation separation are up to 99.30% and 99.73%, respectively. A flotation process was designed for flotation separation of PVC and PET plastics combined with surface modification. This study provides technical insights into physical separation of plastic wastes for recycling industry.

  4. Toxicity of vinyl chloride and poly(vinyl chloride): a critical review.

    PubMed Central

    Wagoner, J K

    1983-01-01

    In 1974, vinyl chloride (VC) was first reported in the open scientific literature to induce angiosarcoma of the liver both in humans and in animals. Additional research has now demonstrated the carcinogenicity of VC to other organs and at lower concentrations. The target organs for VC now clearly include the liver, brain and the lung, and probably the lymphohematopoietic system. The evidence for a carcinogenic risk has been extended to jobs associated with poly(vinyl chloride) exposure. Cases of liver angiosarcoma have been reported among individuals employed in PVC fabrication facilities and an epidemiological study has demonstrated a significant association between exposure to PVC dust and the risk of lung cancer mortality. Cases of angiosarcoma of the liver also have been reported among individuals living in near proximity to vinyl chloride-poly(vinyl chloride) plants. An association between PVC dust and pneumoconiosis also has been demonstrated. On the basis of findings, prudent control of PVC dust in the industrial setting is indicated. PMID:6360677

  5. Dye-sensitized solar cell using 4-chloro-7-nitrobenzofurazan incorporated polyvinyl alcohol polymer electrolyte

    NASA Astrophysics Data System (ADS)

    Senthil, R. A.; Theerthagiri, J.; Madhavan, J.; Arof, A. K.

    2016-11-01

    The influence of 4-chloro-7-nitrobenzofurazan (CNBF) on ionic conductivity of polyvinyl alcohol/KI/I2 (PVA/KI/I2) electrolytes was investigated in the present study. The pure and CNBF incorporated PVA/KI/I2 electrolyte films were prepared by solution casting method using dimethyl sulfoxide as a solvent. These polymer electrolyte films were characterized using Fourier transform infrared spectroscopy, X-ray diffractometer, UV-Vis spectrophotometer and impedance analysis. The ionic conductivities of polymer electrolyte films were calculated from impedance analysis. The pure PVA/KI/I2 electrolyte exhibited the ionic conductivity of 1.649 × 10-5 S cm-1 at room temperature and this value was significantly increased to 1.490 × 10-4 S cm-1 when CNBF was incorporated into the PVA/KI/I2 electrolyte. This might be due to the decrease in the crystallinity of the polymer and increase in the ionic mobility of charge carriers. The performance of the DSSCs using both pure and CNBF incorporated PVA/KI/I2 electrolytes were compared. A DSSC fabricated with CNBF incorporated PVA/KI/I2 electrolyte showed an improved power conversion efficiency of 3.89 % than that of the pure PVA/KI/I electrolyte (1.51 %). These results suggest that CNBF incorporated PVA/KI/I2 electrolyte could be used as a potential electrolyte for DSSC.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  7. Study of ionic liquid immobilization on polyvinyl ferrocene substrates for gas sensor arrays.

    PubMed

    Hou, Kuang-Yu; Rehman, Abdul; Zeng, Xiangqun

    2011-04-19

    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.

  8. In vitro release of metformin hydrochloride from sodium alginate/polyvinyl alcohol hydrogels.

    PubMed

    Martínez-Gómez, Fabián; Guerrero, Juan; Matsuhiro, Betty; Pavez, Jorge

    2017-01-02

    Hydrogels, based on polysaccharides have found a number of applications as drug delivery carriers. In this work, hydrogels of full characterized sodium alginate (Mn 87,400g/mol) and commercial poly(vinyl alcohol) (PVA) sensitive to pH and temperature stimuli were obtained using a simple, controlled, green, low cost method based on freeze-thaw cycles. Stable hydrogels of sodium alginate/PVA with 0.5:1.5 and 1.0:1.0w/v concentrations showed very good swelling ratio values in distilled water (14 and 20g/g, respectively). Encapsulation and release of metformin hydrochloride in hydrogels of 1.0:1.0w/v sodium alginate/PVA was followed by UV spectroscopy. The hydrogel released a very low amount of metformin hydrochloride at pH 1.2; the highest release value (55%) was obtained after 6h at pH 8.0. Also, the release of metformin hydrochloride was studied by (1)H NMR spectroscopy, the temporal evolution of methyl group signals of metformin showed 30% of drug release after 3h.

  9. Effect of salts on the electrospinning of poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Stanger, Jonathan J.; Tucker, Nick; Staiger, Mark; Kirwan, Kerry; Coles, Stuart; Jacobs, Daniel; Larsen, Nigel

    2009-07-01

    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.

  10. Evaluation of polyvinyl alcohol composite membranes containing collagen and bone particles.

    PubMed

    Hameed, Nishar; Glattauer, Veronica; Ramshaw, John A M

    2015-08-01

    Composite biomaterials provide alternative materials that improve on the properties of the individual components and can be used to replace or restore damaged or diseased tissues. Typically, a composite biomaterial consists of a matrix, often a polymer, with one or more fillers that can be made up of particles, sheets or fibres. The polymer matrix can be chosen from a wide range of compositions and can be fabricated easily and rapidly into complex shapes and structures. In the present study we have examined three size fractions of collagen-containing particles embedded at up to 60% w/w in a poly(vinyl alcohol) (PVA) matrix. The particles used were bone particles, which are a mineral-collagen composite and demineralised bone, which gives naturally cross-linked collagen particles. SEM showed well dispersed particles in the PVA matrix for all concentrations and sizes of particles, with FTIR suggesting collagen to PVA hydrogen bonding. Tg of membranes shifted to a slightly lower temperature with increasing collagen content, along with a minor amount of melting point depression. The modulus and tensile strength of membranes were improved with the addition of both particles up to 10 wt%, and were clearly strengthened by the addition, although this effect decreased with higher collagen loadings. Elongation at break decreased with collagen content. Cell adhesion to the membranes was observed associated with the collagen particles, indicating a lack of cytotoxicity.

  11. Improved cellular response on multiwalled carbon nanotube-incorporated electrospun polyvinyl alcohol/chitosan nanofibrous scaffolds.

    PubMed

    Liao, Huihui; Qi, Ruiling; Shen, Mingwu; Cao, Xueyan; Guo, Rui; Zhang, Yanzhong; Shi, Xiangyang

    2011-06-01

    We report the fabrication of multiwalled carbon nanotube (MWCNT)-incorporated electrospun polyvinyl alcohol (PVA)/chitosan (CS) nanofibers with improved cellular response for potential tissue engineering applications. In this study, smooth and uniform PVA/CS and PVA/CS/MWCNTs nanofibers with water stability were formed by electrospinning, followed by crosslinking with glutaraldehyde vapor. The morphology, structure, and mechanical properties of the formed electrospun fibrous mats were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, and mechanical testing, respectively. We showed that the incorporation of MWCNTs did not appreciably affect the morphology of the PVA/CS nanofibers; importantly the protein adsorption ability of the nanofibers was significantly improved. In vitro cell culture of mouse fibroblasts (L929) seeded onto the electrospun scaffolds showed that the incorporation of MWCNTs into the PVA/CS nanofibers significantly promoted cell proliferation. Results from this study hence suggest that MWCNT-incorporated PVA/CS nanofibrous scaffolds with small diameters (around 160 nm) and high porosity can mimic the natural extracellular matrix well, and potentially provide many possibilities for applications in the fields of tissue engineering and regenerative medicine.

  12. Anomalous electrical transport properties of polyvinyl alcohol-multiwall carbon nanotubes composites below room temperature

    NASA Astrophysics Data System (ADS)

    Chakraborty, G.; Gupta, K.; Meikap, A. K.; Babu, R.; Blau, W. J.

    2011-02-01

    The dc and ac electrical transport property of polyvinyl alcohol-multiwall carbon nanotubes composites has been investigated within a temperature range 77≤T≤300 K and in the frequency range 20 Hz-1 MHz in presence as well as in absence of a transverse magnetic field up to 1 T. The dc conductivity follows variable range hopping model. The magnetoconductivity of the samples changes a sign from positive to negative with an increase in temperature which can be interpreted by the dominancy of the quantum interference effect over the wave function shrinkage effect. The ac conductivity follows a power law whereas the temperature dependence of frequency exponent s can be explained by correlated barrier hopping model. The dielectric behavior of the samples has been governed by the grain and grain boundary resistance and capacitance. The ac conductivity reduces with the application of magnetic field. Although the theoretical model to explain it, is still lacking, we may conclude that this is due to the increase in grain and grain boundary resistance by the application of magnetic field.

  13. Dye Adsorption Behavior of Polyvinyl Alcohol/Glutaraldehyde/β-Cyclodextrin Polymer Membranes

    NASA Astrophysics Data System (ADS)

    Ghemati, Dj.; Aliouche, Dj.

    2014-05-01

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

  14. Nonlinear optical characterization of the Ag nanoparticles doped in polyvinyl alcohol films

    NASA Astrophysics Data System (ADS)

    Ghanipour, Mahshad; Dorranian, Davoud

    2015-06-01

    The effect of silver nanoparticles doped in polyvinyl alcohol (PVA) on the nonlinear optical properties of composite films is studied experimentally. Samples are PVA films of 0.14 mm thickness doped with different concentrations of silver nanoparticles. Nonlinear optical properties of doped polymer films are studied experimentally employing Z-scan techniques. Experiments are performed using the second harmonic of a continuous Nd-Yag laser beam at 532 nm wavelength and 45 mW power. The effect of nonlinear refractive index of samples is obtained by measuring the profile of propagated beam through the samples and their nonlinear refractive index is found to be negative. The nonlinear absorption coefficient is calculated using open aperture Z-scan data while its nonlinear refractive index is measured using the closed aperture Z-scan data, leads to measuring the third order susceptibility |χ(3)|. Real and imaginary parts of the third-order nonlinear optical susceptibility |χ(3)| are decrease with increasing the concentration of Ag nanoparticles in the films. The values of thermo-optic coefficient are determined at different concentrations of silver nanoparticles for samples.

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

    PubMed Central

    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

    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

  16. Superhydrophobic, nanotextured polyvinyl chloride films for delaying Pseudomonas aeruginosa attachment to intubation tubes and medical plastics.

    PubMed

    Loo, Ching-Yee; Young, Paul M; Lee, Wing-Hin; Cavaliere, Rosalia; Whitchurch, Cynthia B; Rohanizadeh, Ramin

    2012-05-01

    Bacterial attachment onto the surface of polymers in medical devices such as polyvinyl chloride (PVC) is influenced by the physicochemical properties of the polymer, including its surface hydrophobicity and roughness. In this study, to prevent biofilm formation onto PVC devices, the PVC surface was modified using a combination of solvent (tetrahydrofuran) and non-solvents (i.e. ethanol and methanol). The surface of unmodified PVC was smooth and relatively hydrophobic (water contact angle (CA)=80°). Ethanol-treated PVCs revealed the presence of micron-sized particulates and porous structures as the concentration of ethanol was increased. Surface hydrophobicity (measured in terms of CA) increased from 73° to 150° as the ethanol concentration increased from 15% to 35% (v/v). In general, methanol-treated PVCs were more hydrophilic compared to those treated with ethanol. The colonization of Pseudomonas aeruginosa PAO1 onto unmodified PVC surface was rapid, and individual bacterial cells could be seen after 6h incubation. On the surface of treated PVC, the secretion of extracellular matrix layers was evident at 18 h and P. aeruginosa PAO1 start to form microcolonies at 24h of incubation. The initial attachment of P. aeruginosa PAO1 was delayed to 18 and 24h, respectively in the PVCs treated with 25% (v/v) and 35% (v/v) ethanol. It can be concluded that the treatment used in this study to prepare superhydrophobic PVC surface prevented the colonization of bacteria up to 24h after culture.

  17. Development of active polyvinyl alcohol/β-cyclodextrin composites to scavenge undesirable food components.

    PubMed

    López-de-Dicastillo, Carol; Jordá, María; Catalá, Ramón; Gavara, Rafael; Hernández-Muñoz, Pilar

    2011-10-26

    Active food packaging systems based on the incorporation of agents into polymeric package walls are being designed to purposely release or retain compounds to maintain or even increase food quality. The objective of this work was to develop polyvinyl alcohol (PVOH)/β-cyclodextrin (βCD) composite films that can be applied to reduce undesirable component content such as cholesterol in foods through active retention of the compounds in the package walls during storage. Cyclodextrins were added to PVOH in a proportion of 1:1 and cross-linked with glyoxal under acidic media to reduce its water-soluble character. Three different cross-linking procedures were used: cross-linking of the polymer/polysaccharide mixture in solution and film casting, PVOH. βCD*; cross-linking of the polymer, addition of βCD, and casting of the mixture, PVOH*.CD; and casting of a PVOH film, addition of a βCD/glyoxal solution onto the film, and cross-linking during drying, PVOH.CD*. Characterization studies showed that the PVOH*.CD and PVOH.CD* films provided the best physical characteristics with the lowest release values and the highest barrier properties. As a potential application, materials were tested as potential cholesterol-scavenging films. There was a significant reduction in the cholesterol concentration in milk samples when they were exposed to the materials developed.

  18. Characterization of a polyvinyl alcohol-hydrogel artificial articular cartilage prepared by injection molding.

    PubMed

    Kobayashi, Masanori; Oka, Masanori

    2004-01-01

    We have developed a hip hemi-arthroplasty using polyvinyl alcohol-hydrogel (PVA-H) as the treatment for hip joint disorders in which the lesion is limited to the joint surface. In previous studies, we characterized the biocompatibility and the mechanical properties of PVA-H as an arthroplasty material. To fix PVA-H firmly to the bone, we have devised an implant composed of PVA-H and porous titanium fiber mesh (TFM). However, because of poor infiltration of the PVA solution into the pores of the TFM when using the low temperature crystallization method, the strength of the PVA-H-TFM interface was insufficient. Consequently, the infiltration method was improved by adopting high-pressure injection molding. With this improved method, the bonding strength of the interface increased remarkably. However, as this injection molding requires high temperature, various mechanical properties of the PVA-H might change with this treatment in comparison with the previous method. The purpose of this study was to investigate the effect of high temperature treatment on the mechanical properties of PVA-H as artificial articular cartilage, the tensile test and friction test were performed about new PVA-H. The results showed no significant mechanical deterioration of the PVA-H. This certified that the injection-molding method did not induce the change of the mechanical properties of PVA-H and indicated the potential of hemi-arthroplasty using PVA-H by this method in the future.

  19. Dehydration of dioxane by pervaporation using filled blend membranes of polyvinyl alcohol and sodium alginate.

    PubMed

    Kuila, Sunil Baran; Ray, Samit Kumar

    2014-01-30

    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.

  20. Surface stiffening and enhanced photoluminescence of ion implanted cellulose - polyvinyl alcohol - silica composite.

    PubMed

    Shanthini, G M; Sakthivel, N; Menon, Ranjini; Nabhiraj, P Y; Gómez-Tejedor, J A; Meseguer-Dueñas, J M; Gómez Ribelles, J L; Krishna, J B M; Kalkura, S Narayana

    2016-11-20

    Novel Cellulose (Cel) reinforced polyvinyl alcohol (PVA)-Silica (Si) composite which has good stability and in vitro degradation was prepared by lyophilization technique and implanted using N(3+) ions of energy 24keV in the fluences of 1×10(15), 5×10(15) and 1×10(16)ions/cm(2). SEM analysis revealed the formation of microstructures, and improved the surface roughness on ion implantation. In addition to these structural changes, the implantation significantly modified the luminescent, thermal and mechanical properties of the samples. The elastic modulus of the implanted samples has increased by about 50 times compared to the pristine which confirms that the stiffness of the sample surface has increased remarkably on ion implantation. The photoluminescence of the native cellulose has improved greatly due to defect site, dangling bonds and hydrogen passivation. Electric conductivity of the ion implanted samples was improved by about 25%. Hence, low energy ion implantation tunes the mechanical property, surface roughness and further induces the formation of nano structures. MG63 cells seeded onto the scaffolds reveals that with the increase in implantation fluence, the cell attachment, viability and proliferation have improved greatly compared to pristine. The enhancement of cell growth of about 59% was observed in the implanted samples compared to pristine. These properties will enable the scaffolds to be ideal for bone tissue engineering and imaging applications.

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

    NASA Astrophysics Data System (ADS)

    Mahmoud, K. H.

    2015-03-01

    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 400 nm 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 4.8 eV, which reduced to 4.45 eV 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 0.04 wt% Ag NPs composite sample effect was strong against S. aureus.

  2. Radiation crosslinking and scission of poly(vinyl methyl ether) in aqueous solution

    NASA Astrophysics Data System (ADS)

    Janik, Ireneusz; Rosiak, Janusz M.

    2002-03-01

    For a wide range of poly(vinyl methyl ether) (PMVE) concentrations (1-16 g dm -3), in anoxic conditions, polymer-derived radicals recombine in two major pathways: (i) crosslinking and (ii) disproportionation. Both these processes proceed inter- and intramolecularly. The radiation-chemical yields and kinetics of crosslinking have been studied by pulse radiolysis with light scattering intensity detection (LSI). In the absence of oxygen, G-values of intermolecular crosslinking were determined on the basis of LSI changes versus applied dose and compared with the results obtained previously for γ-irradiated samples. It has been found that the first half-life time of intermolecular crosslinking decreases with increasing dose per pulse. Addition of small amounts of macroradical scavenger (cysteamine hydrochloride) decreases, drastically, the increase of LSI signal. On increasing the PVME concentration, intermolecular crosslinking becomes more efficient. In the presence of oxygen, for diluted PVME solution (0.1 g dm -3), decrease of LSI signal consisting of the kinetic of a first-order reaction was observed. The rate constant of LSI decrease was found to be 1.1×10 3 s -1 and it was attributed to the main-chain scission.

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

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    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).

  4. Rate-dependent Mechanical Deformation Behavior of POSS-filled and Plasticized Poly(vinyl chloride).

    NASA Astrophysics Data System (ADS)

    Soong, Sharon; Cohen, Robert; Boyce, Mary

    2006-03-01

    In different temperatures or strain-rate regimes, the rate sensitivities of polymers change as various primary and secondary molecular mobility mechanisms are accessed. Incorporating nanoparticles into the polymer matrix can potentially alter the molecular level structure and offers an opportunity to tailor the rate-dependent mechanical deformation behavior of the polymer. In this study, methacryl-POSS (C56H88O28Si8) and dioctyl phthalate (DOP) were incorporated into poly(vinyl chloride) (PVC) through melt blending. Dynamic Mechanical Analysis revealed that the incorporation of POSS in PVC plasticizes PVC and reduces both the alpha and beta transition temperatures. As for the PVC/DOP blends, while the alpha-transition temperatures were reduced, beta-motions vanishes with high DOP contents. The rate dependent yield behavior is characterized in compression testing. Zwick Mechine is used for low to moderate strain rate (0.0001 to 0.1/s) and Split Hopkinson Bar is used for high strain rate (500 to 2000/s). It was found that PVC with POSS shows a delay in yield strength rate-sensitivity transition. For PVC with higher DOP contents which show restricted beta-motions, the rate-sensitivity transition in yield stress faded away. Constitutive model used was able to predict the rate-sensitivity transitions in the compression yield behavior of PVC compounds.

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

    SciTech Connect

    Shah, Chetan P.; Singh, Krishan K.; Kumar, Manmohan; Bajaj, Parma N.

    2010-01-15

    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.

  6. Preparation and properties of nanometer silk fibroin peptide/polyvinyl alcohol blend films for cell growth.

    PubMed

    Luo, Qin; Chen, Zhongmin; Hao, Xuefei; Zhu, Qiangsong; Zhou, Yucheng

    2013-10-01

    Nanometer silk fibroin peptide (Nano-SFP) was prepared from silkworm cocoons through the process of dissolution, dialysis and enzymolysis. For comparison, silk fibroin was decomposed with α-chymotrypsin, trypsin and neutrase, respectively. From the SEM and particle size analysis results, the Nano-SFP prepared by neutrase was found to be the most desirable at about 50-200 nm. Nano-SFP/polyvinyl alcohol films (Nano-SFP/PVA) were prepared by blending Nano-SFP and PVA in water with different weight ratios of 10/90, 20/80, 30/70, and 40/60. The films were characterized by IR, SEM, TG, DSC and tensile strength test for investigating their structure, surface morphology, thermostability, and mechanical property. The results showed that Nano-SFP inserted in the PVA films with small linear particles, and Nano-SFP/PVA films exhibited smooth surface, good thermostability and tensile strength. The growth of Chinese hamster ovary (CHO) cells on films with and without Nano-SFP was investigated with MTT colorimetric assay to assess the films' ability to promote cell growth. It was observed that the Nano-SFP improved cell adhesion on the film surface, and the ability of promoting cell growth increased with the increasing content of Nano-SFP in the blend films. Nano-SFP/PVA film with the ratio of 30/70 was concluded to have the best properties.

  7. Voriconazole Composited Polyvinyl Alcohol/Hydroxypropyl-β-Cyclodextrin Nanofibers for Ophthalmic Delivery

    PubMed Central

    Sun, Xiaoyi; Cai, Zhengyuan; Yu, Lingyan; Lv, Yuanyuan

    2016-01-01

    Voriconazole (VRC) incorporated in composited polyvinyl alcohol (PVA)/hydroxypropyl-β-cyclodextrin (HPβCD) blended nanofibers were produced via electrospinning for efficient ophthalmic delivery. The VRC loading capacity increased with increasing HPβCD content. The optimal solution for electrospinning consisted of 8% (w/v) PVA, 4% (w/v) HPβCD and 0.5% (w/v) VRC. The nanofibers exhibited bead-free average fiber diameters of 307±31 nm and VRC was released in vitro in a sustained manner. The VRC nanofibers were characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The proton nuclear magnetic resonance (1H-NMR) was used to analyze the molar ratio of HPβCD/VRC in the nanofibers. Compared with a VRC solution, the nanofibers significantly prolonged the half life, and increased the bioavailability of VRC in rabbit tears. No obvious signs of irritation were observed after application in the conjunctival sac. VRC nanofibers are promising for ophthalmic drug delivery and further pharmacodynamics studies are needed. PMID:27974859

  8. Thermal, mechanical and dielectric properties of poly(vinyl alcohol)/graphene oxide composites

    NASA Astrophysics Data System (ADS)

    Rathod, Sunil G.; Bhajantri, R. F.; Ravindrachary, V.; Pujari, P. K.; Sheela, T.; Naik, Jagadish

    2014-04-01

    In this work the composite films of poly(vinyl alcohol) (PVA) doped with functionalized Graphene Oxide (GO) were prepared by solution casting method. The films were characterized using FT-IR, DSC, XRD, mechanical properties and dielectric studies at room temperature. FTIR spectra shows the formation of hydrogen bonds between hydroxyl groups of PVA and the hydroxy groups of GO. The DSC thermograms shows the addition of GO to PVA greatly improves the thermal stability of the composites. XRD patterns shows that the GO exfoliated and uniformly dispersed in PVA matrix. Mechanical properties are significantly improved in PVA/GO composites. The tensile strength increased from 8.2 to 13.7 MPa and the Young's modulus increased from 7.5 to 24.8 MPa for 5 wt% GO doped sample. Dielectric spectroscopy showed a highest dielectric constant for the 5 wt% GO doped PVA films. This work provides a potential design strategy on PVA/GO composite, which would lead to higher-performance, flexible dielectric materials, high charge-storage devices.

  9. Surface modified electrospun poly(vinyl alcohol) membranes for extracting nanoparticles from water

    NASA Astrophysics Data System (ADS)

    Mahanta, Narahari; Valiyaveettil, Suresh

    2011-11-01

    Contamination of water from nanomaterials will be an emerging problem in the future due to incorporation of nanomaterials in many commercial products and improper disposal of waste materials. In this report, electrospun polyvinyl alcohol nanofibers (PVA NFs) with diameters ranging between 300 and 500 nm were used for the extraction of nanosized contaminants from the aqueous environment. To obtain the best extraction efficiency, surface hydroxyl groups of PVA NFs were chemically modified with functional groups, such as thiols and amines. Two model nanoparticles (silver and gold) dissolved in water were used for adsorption studies. Depending on the nature of the surface functionalities, the fibers showed unique ability to adsorb nanoparticles. The extraction studies revealed that the amine and thiol modified PVA NFs showed 90% extraction efficiency for both silver and gold nanoparticles. The thiol and amine functionalized PVA NFs showed maximum adsorption capacities (Qt) towards Au NPs, which were around 79-84 mg g-1. Similarly for Ag NP extraction, amine functionalized PVA NFs showed a value for Qt at 56 mg g-1. Our results highlight that functionalized nanofibers have high extraction efficiency for dissolved nanoparticles in water and can be used for removal of the nanocontaminants from the aqueous environment.Contamination of water from nanomaterials will be an emerging problem in the future due to incorporation of nanomaterials in many commercial products and improper disposal of waste materials. In this report, electrospun polyvinyl alcohol nanofibers (PVA NFs) with diameters ranging between 300 and 500 nm were used for the extraction of nanosized contaminants from the aqueous environment. To obtain the best extraction efficiency, surface hydroxyl groups of PVA NFs were chemically modified with functional groups, such as thiols and amines. Two model nanoparticles (silver and gold) dissolved in water were used for adsorption studies. Depending on the nature of

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

    PubMed

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

    2013-04-01

    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 μm. 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.

  11. Recovery of agricultural odors and odorous compounds from polyvinyl fluoride film bags.

    PubMed

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

    2010-01-01

    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 μg m(-3)) and seven volatile fatty acids: acetic (2,311 μg m(-3)), propionic (15,800 μg m(-3)), isobutyric (1,686 μg m(-3)), butyric (1,049 μg m(-3)), isovaleric (1,236 μg m(-3)), valeric (643 μg m(-3)), and hexanoic (2,158 μg 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.

  12. Analysis of isothiazolinone preservatives in polyvinyl alcohol cooling towels used in Japan.

    PubMed

    Kawakami, Tsuyoshi; Isama, Kazuo; Ikarashi, Yoshiaki

    2014-09-19

    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., laboratory-simulation and volunteer) of washing experiments were conducted to evaluate the effect of washing procedures. Qualitative and quantitative analyses were performed by LC/MS/MS, which detected 2-methyl-4-isothiazolin-3-one (MI) and 5-chloro-2-methyl-4-isothaizolin-3-one (CMI) in 23 samples (MI: 0.29-154 μg g-wet(-1), CMI: 2.2-467 μg g-wet(-1)), 2-n-octyl-4-isothiazolin-3-one (OIT) in one sample (478 μg g-wet(-1)). The compounds 4,5-Dichloro-2-n-octyl-4-isothiazolin-3-one (2Cl-OIT) and 1,2-benzisothiazolin-3-one (BIT) were not detected in all samples. We confirmed the presence of residual MI, CMI, and OIT in the washed towels, and the residual-to-original content ratio of OIT was higher than that of MI and CMI in PVA towels, due to the higher hydrophobicity of OIT than MI and CMI. A concern has been raised about the occurrence of contact dermatitis being caused by the use of PVA towels. It is suggested that a detailed description of isothiazolinone preservatives in PVA towels and an effective washing procedure for the removal of these preservatives should be provided by the manufacturer. Further, alternative non-sensitizing preservatives might be considered for the manufacture of PVA cooling towels in the future.

  13. Nanoparticle penetration of human cervicovaginal mucus: The effect of polyvinyl alcohol

    PubMed Central

    Yang, Ming; Lai, Samuel K.; Yu, Tao; Wang, Ying-Ying; Happe, Christina; Zhong, Weixi; Zhang, Michael; Anonuevo, Abraham; Fridley, Colleen; Hung, Amy; Fu, Jie; Hanes, Justin

    2014-01-01

    Therapeutic nanoparticles must rapidly penetrate the mucus secretions lining the surfaces of the respiratory, gastrointestinal and cervicovaginal tracts to efficiently reach the underlying tissues. Whereas most polymeric nanoparticles are highly mucoadhesive, we previously discovered that a dense layer of low MW polyethylene glycol (PEG) conferred a sufficiently hydrophilic and uncharged surface to effectively minimize mucin-nanoparticle adhesive interactions, allowing well-coated particles to rapidly diffuse through human mucus. Here, we sought to investigate the influence of surface coating by polyvinyl alcohol (PVA), a relatively hydrophilic and uncharged polymer routinely used as a surfactant to formulate drug carriers, on the transport of nanoparticles in fresh human cervicovaginal mucus. We found that PVA-coated polystyrene (PS) particles were immobilized, with speeds at least 4,000-fold lower in mucus than in water, regardless of the PVA molecular weight or incubation concentration tested. Nanoparticles composed of poly(lactide-co-glycolide) (PLGA) or diblock copolymers of PEG-PLGA were similarly immobilized when coated with PVA (slowed 29,000- and 2,500-fold, respectively). PVA coatings could not be adequately removed upon washing, and the residual PVA prevented sufficient coating with Pluronic F127 capable of reducing particle mucoadhesion. In contrast to PVA-coated particles, the similar sized PEG-coated formulations were slowed only ~6- to 10-fold in mucus compared to in water. Our results suggest incorporating PVA in the particle formulation process may lead to the formation of mucoadhesive particles for many nanoparticulate systems. Thus, alternative methods for particle formulation, based on novel surfactants or changes in the formulation process, should be identified and developed in order to produce mucus-penetrating particles for mucosal applications. PMID:25090196

  14. Elastic properties of thin poly(vinyl alcohol)-cellulose nanocrystal membranes.

    PubMed

    Pakzad, A; Simonsen, J; Yassar, R S

    2012-02-01

    In spite of extensive studies on the preparation and characterization of nanocomposite materials, the correlation of their properties at the nanoscale with those in bulk is a relatively unexplored area. This is of great importance, especially for materials with potential biomedical applications, where surface properties are as important in determining their applicability as bulk characteristics. In this study, the nanomechanical characteristics of thin poly(vinyl alcohol) (PVOH)-poly(acrylic acid) (PAA)-cellulose nanocrystal (CNC) membranes were studied using the nanoindentation module in an atomic force microscope (AFM) and the properties were compared with the macro-scale properties obtained by tensile tests. In general, the elastic properties measured by nanoindentation followed the same trend as macro-scale tensile tests except for the PVOH 85-PAA 0-CNC 15 sample. In comparison to the macro-scale elastic properties, the measured elastic moduli with AFM were higher. Macro-scale tensile test results indicated that, in the presence of PAA, incorporation of CNCs up to 20 wt% improved the elastic modulus of PVOH, but when no PAA was added, increasing the CNC content above 10 wt% resulted in their agglomeration and degradation in mechanical properties of PVOH. The discrepancy between macro-scale tensile tests and nanoindentation in the PVOH 85-PAA 0-CNC 15 sample was correlated to the high degree of inhomogeneity of CNC dispersion in the matrix. It was found that the composites reinforced with cellulose nanocrystals had smaller indentation imprints and the pile-up effect increased with the increase of cellulose nanocrystal content.

  15. Poly(vinyl alcohol)-based film potentially suitable for antimicrobial packaging applications.

    PubMed

    Musetti, Alessandro; Paderni, Katia; Fabbri, Paola; Pulvirenti, Andrea; Al-Moghazy, Marwa; Fava, Patrizia

    2014-04-01

    This work aimed at developing a thin and water-resistant food-grade poly(vinyl alcohol) (PVOH)-based matrix able to swell when in contact with high moisture content food products without rupturing to release antimicrobial agents onto the food surface. This film was prepared by blending PVOH and 7.20% (wt/wt of PVOH) of poly(ethylene glycol) (PEG) with citric acid as crosslinking agent. The film-forming solution was then casted onto a flat surface and the obtained film was 60 μm in thickness and showed a good transparency (close to T = 100%) in the visible region (400 to 700 nm). After immersion in water for 72 h at room temperature, the crosslinked matrix loses only 19.2% of its original weight (the percentage includes the amount of unreacted crosslinking agent, antimicrobial in itself). Water content, degree of swelling, and crosslinking density of the film prove that the presence of PEG diminishes the hydrophilic behavior of the material. Also the mechanical properties of the wet and dry film were assessed. Alongside this, 2.5% (wt/wt of dry film) of grapefruit seed extract (GSE), an antimicrobial agent, was added to the film-forming solution just before casting and the ability of the plastic matrix to release the additive was then evaluated in vitro against 2 GSE-susceptible microorganisms, Salmonella enteritidis and Listeria innocua. The results indicate that the developed matrix may be a promising food-grade material for the incorporation of active substances.

  16. Poly(vinyl ester) Block Copolymers Synthesized by Reversible Addition−Fragmentation Chain Transfer Polymerizations

    SciTech Connect

    Lipscomb, Corinne E.; Mahanthappa, Mahesh K.

    2009-07-31

    Homopolymerizations and block copolymerizations of vinyl acetate (VAc), vinyl pivalate (VPv), and vinyl benzoate (VBz) by reversible addition-fragmentation chain transfer (RAFT) polymerization have been studied. Polymerizations of VAc initiated with 2,2{prime}-azobis(isobutyronitrile) (AIBN) at 60 C using two different xanthate RAFT agents C{sub 2}H{sub 5}OC(=S)SR (R = -CH(CH{sub 3})CO{sub 2}C{sub 2}H{sub 5} (1) and -CH(CH{sub 3})O{sub 2}CC(CH{sub 3}){sub 3} (2)) were examined to elucidate the dependence of the polydispersities of the resulting polymers on the RAFT agent leaving group R. RAFT agent 2, in which the leaving R-group mimics a growing vinyl ester polymer chain, consistently yields poly(vinyl acetates) having broader polydispersities than those synthesized using 1 (M{sub n} = 3.6-14 kg/mol and M{sub w}/M{sub n} = 1.15-1.33). While VPv exhibits similar controlled polymerization behavior to VAc, RAFT homopolymerizations of VBz mediated by 1 indicate this electron-deficient vinyl ester requires higher temperatures to effect controlled polymerizations to yield polymers having M{sub n} = 4-14 kg/mol and M{sub w}/M{sub n} = 1.29-1.53. Chain extension reactions from xanthate-terminated vinyl ester homopolymers with VAc, VPv, and VBz proceed with variable efficiencies to furnish block copolymers that microphase separate in the melt state as determined by small-angle X-ray scattering.

  17. Separation of polyvinyl chloride (PVC) from automobile shredder residue (ASR) by froth flotation with ozonation.

    PubMed

    Reddy, Mallampati Srinivasa; Kurose, Keisuke; Okuda, Tetsuji; Nishijima, Wataru; Okada, Mitsumasa

    2007-08-25

    The purpose of this study is to develop froth flotation to separate polyvinyl chloride (PVC) from automobile shredder residue (ASR) plastic mixtures of variable composition. Some polymers in ASR polymer mixtures have similar density and hydrophobicity with PVC and thus selective flotation of PVC from ASR polymer mixtures cannot be achieved. The present study focused on the surface modification of PVC with ozonation, and then the modified PVC can be separated from other polymers by the following froth flotation. The results of this study indicate that the selective recovery of PVC from real ASR polyethylene tetra pethelate (PET), polymethyl methacrylate (PMMA), polybutyl methacralate (PBMA), ethyl acrylate (EA), polycarbonate (PC) and rubber mixtures can be accomplished in a three-step process involving a gravity separation, ozonation and froth flotation. The rubber was removed from other heavy ASR (PVC, PET, PMMA, PBMA, EA and PC) polymers by froth flotation without mixing. It was found that ozonation process produced the desired difference in contact angle required (from 89.5 to 73.0 degrees ) for separation of PVC from other heavy ASR polymers, whereas the contact angles of other polymers was slightly decreased. The most of the load ASR, i.e. about 72.4% is floated away and 27.6% was settled down. The highest component 96.7% of PVC was recovered in the settled fraction. As a result of this research effort, the surface modification of PVC with ozonation can be efficiently useful to separate the PVC from other similar density ASR mixed polymers.

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

    NASA Astrophysics Data System (ADS)

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

    2002-11-01

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

  19. Poly(vinyl alcohol)-heparin biosynthetic microspheres produced by microfluidics and ultraviolet photopolymerisation

    PubMed Central

    Young, Cara; Rozario, Kester; Serra, Christophe; Poole-Warren, Laura; Martens, Penny

    2013-01-01

    Biosynthetic microspheres have the potential to address some of the limitations in cell microencapsulation; however, the generation of biosynthetic hydrogel microspheres has not been investigated or applied to cell encapsulation. Droplet microfluidics has the potential to produce more uniform microspheres under conditions compatible with cell encapsulation. Therefore, the aim of this study was to understand the effect of process parameters on biosynthetic microsphere formation, size, and morphology with a co-flow microfluidic method. Poly(vinyl alcohol) (PVA), a synthetic hydrogel and heparin, a glycosaminoglycan were chosen as the hydrogels for this study. A capillary-based microfluidic droplet generation device was used, and by varying the flow rates of both the polymer and oil phases, the viscosity of the continuous oil phase, and the interfacial surface tension, monodisperse spheres were produced from ∼200 to 800 μm. The size and morphology were unaffected by the addition of heparin. The modulus of spheres was 397 and 335 kPa for PVA and PVA/heparin, respectively, and this was not different from the bulk gel modulus (312 and 365 for PVA and PVA/heparin, respectively). Mammalian cells encapsulated in the spheres had over 90% viability after 24 h in both PVA and PVA/heparin microspheres. After 28 days, viability was still over 90% for PVA-heparin spheres and was significantly higher than in PVA only spheres. The use of biosynthetic hydrogels with microfluidic and UV polymerisation methods offers an improved approach to long-term cell encapsulation. PMID:24404042

  20. Development of polyvinyl chloride biofilms for succession of selected marine bacterial populations.

    PubMed

    Balasubramanian, V; Palanichamy, S; Subramanian, G; Rajaram, R

    2012-01-01

    Present investigation was made to bring out the pattern of biofilm formation by heterotrophic bacteria on nontoxic material, polyvinyl chloride (PVC) sheet fitted wooden rack that was immersed in seawater and the study was conducted in Tuticorin coast. Samplings were made over a period of 7 days with the following time period intervals: 30 min, 1, 2, 4, 24, 48, 72, 96, 120 and 144 hr. Bacterial enumeration was made by spread plate method on nutrient agar medium and characterization of bacterial isolates up to generic level was done. Gram-negative bacteria like Pseudomonas sp., Enterobacter sp., Aeromonas sp., Cytophaga sp. and Flavobacterium sp. were found to be the pioneer in colonizing the surface within 30 min and seven genera were represented in the biofilm. Among them two genera were found belonging to Gram-positive groups which included Micrococcus and Bacillus sp. The early stage biofilm i.e. up to 24th hr was wholly constituted by Gram-negative groups. However, the population density of Pseudomonas sp. was found to be higher (315 CFU) when compared to other Gram-negative forms. Occurrence of Gram-positive group was noted only at 48th hr old biofilm (28 to 150 CFU). The period between 48 and 96th hr was the transition where both the Gram-negative and Gram-positive groups co- existed. After 96th hr, the biofilm was found constituted only by Gram-positive groups. The isolates of early stage biofilm were found to produce allelopathic substance like bacteriocin.