Science.gov

Sample records for alcohol pva solution

  1. Closantel nano-encapsulated polyvinyl alcohol (PVA) solutions.

    PubMed

    Vega, Abraham Faustino; Medina-Torres, Luis; Calderas, Fausto; Gracia-Mora, Jesus; Bernad-Bernad, MaJosefa

    2016-08-01

    The influence of closantel on the rheological and physicochemical properties (particle size and by UV-Vis absorption spectroscopy) of PVA aqueous solutions is studied here. About 1% PVA aqueous solutions were prepared by varying the closantel content. The increase of closantel content led to a reduction in the particle size of final solutions. All the solutions were buffered at pH 7.4 and exhibited shear-thinning behavior. Furthermore, in oscillatory flow, a "solid-like" type behavior was observed for the sample containing 30 μg/mL closantel. Indicating a strong interaction between the dispersed and continuous phases and evidencing an interconnected network between the nanoparticle and PVA, this sample also showed the highest shear viscosity and higher shear thinning slope, indicating a more intrincate structure disrupted by shear. In conclusion, PVA interacts with closantel in aqueous solution and the critical concentration for closantel encapsulation by PVA was about 30 μg/mL; above this concentration, the average particle size decreased notoriously which was associated to closantel interacting with the surface of the PVA aggregates and thus avoiding to some extent direct polymer-polymer interaction. PMID:26330226

  2. The development of polyvinyl alcohol (PVA) fibers

    SciTech Connect

    Zheng, Q.; Morgan, R.J.; Cunniff, P.

    1996-12-31

    The conditions for gel-spinning and hot drawing of PVA fibers have been investigated and the effects of simultaneous orientation and chemical crosslinking in hot water and other solution environments studied. Fibers with high tenacities ({approximately}30 g/d) were produced but more precise control of spinning conditions will be required to obtain consistent high fiber tenacities. The fiber mechanical energy absorption can be further enhanced by boiling water exposure that causes additional crystallization and, also, disorientation of the fiber amorphous regions that results in a softer but high energy absorbing PVA fiber with 30-60% greater failure strain without any compromise in fiber strength. Such treated fibers have the potential to exhibit superior ballistic resistance and cost advantage relative to other fibers.

  3. Anammox sludge immobilized in polyvinyl alcohol (PVA) cryogel carriers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study evaluated the use of polyvinyl alcohol (PVA) cryogels to encapsulate slow-growing anammox bacteria for deammonification treatment of wastewater. The cryogel pellets were prepared by a freezing-thawing procedure at -8 oC. On average, pellets contained 11.8 mg TSS/g-pellet of enriched anamm...

  4. Property-based design: optimization and characterization of polyvinyl alcohol (PVA) hydrogel and PVA-matrix composite for artificial cornea.

    PubMed

    Jiang, Hong; Zuo, Yi; Zhang, Li; Li, Jidong; Zhang, Aiming; Li, Yubao; Yang, Xiaochao

    2014-03-01

    Each approach for artificial cornea design is toward the same goal: to develop a material that best mimics the important properties of natural cornea. Accordingly, the selection and optimization of corneal substitute should be based on their physicochemical properties. In this study, three types of polyvinyl alcohol (PVA) hydrogels with different polymerization degree (PVA1799, PVA2499 and PVA2699) were prepared by freeze-thawing techniques. After characterization in terms of transparency, water content, water contact angle, mechanical property, root-mean-square roughness and protein adsorption behavior, the optimized PVA2499 hydrogel with similar properties of natural cornea was selected as a matrix material for artificial cornea. Based on this, a biomimetic artificial cornea was fabricated with core-and-skirt structure: a transparent PVA hydrogel core, surrounding by a ringed PVA-matrix composite skirt that composed of graphite, Fe-doped nano hydroxyapatite (n-Fe-HA) and PVA hydrogel. Different ratio of graphite/n-Fe-HA can tune the skirt color from dark brown to light brown, which well simulates the iris color of Oriental eyes. Moreover, morphologic and mechanical examination showed that an integrated core-and-skirt artificial cornea was formed from an interpenetrating polymer network, no phase separation appeared on the interface between the core and the skirt. PMID:24464723

  5. Ultrasonic Velocity, Viscosity and Refractive Index Investigation on Interacting Blend Solutions of PAA (Poly Acrylic Acid) and PVA (Poly Vinyl Alcohol) in Solvent DMSO (Di methyl Sulphoxide)

    NASA Astrophysics Data System (ADS)

    Nagamani, Chakrala

    2010-11-01

    The present study provides a great insight into the major new research areas like Plasma research (which is yielding a greater understanding of the universe) and Nano Technology Research (which provides many practical uses like Drug Delivery System). The Ultrasonic Velocities, Viscosities and Refractive indices of Poly (Acrylic Acid) and Poly (Vinyl Alcohol) blends in DMSO solutions have been measured over a wide range of composition, concentration and at different temperatures. The variation of Ultrasonic Velocity, derived acoustical parameters, adiabatic compressibility, acoustic impedance, Rao number, molar compressibility and relaxation strength with composition of blend solution was found not linear. This non-linearity has been attributed to incompatibility in conformity with the earlier findings. This behavior was confirmed by Viscometric and interaction parameters studies, as well as by investigation of Refractive index studies. These investigations offer an entirely new and simple approach to the study of the compatibility of polymer blends which is in general obtained by sophisticated techniques of thermal dynamic mechanical and electron microscopic analysis.

  6. 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.

  7. Crystal structures and magnetic properties of magnetite (Fe3O4)/Polyvinyl alcohol (PVA) ribbon

    NASA Astrophysics Data System (ADS)

    Ardiyanti, Harlina; Suharyadi, Edi; Kato, Takeshi; Iwata, Satoshi

    2016-04-01

    Ribbon of magnetite (Fe3O4)/Polyvinyl Alcohol (PVA) nanoparticles have been successfully fabricated with various concentration of PVA synthesized by co-precipitation method. Particle size of nanoparticles Fe3O4 sample and ribbon Fe3O4/PVA 25% sample is about 9.34 nm and 11.29 nm, respectively. The result of Vibrating Sample Magnetometer (VSM) showed that saturation magnetization value decreased from 76.99 emu/g to 15.01 emu/g and coercivity increased from 49.30 Oe to 158.35 Oe as increasing concentration of PVA. Atomic Force Microscopy (AFM) analysis showed that encapsulated PVA given decreasing agglomeration, controlled shape of nanoparticles Fe3O4 more spherical and dispersed. Surface roughness decreased with increasing concentration of PVA.

  8. Fabrication of silver nanoparticles embedded into polyvinyl alcohol (Ag/PVA) composite nanofibrous films through electrospinning for antibacterial and surface-enhanced Raman scattering (SERS) activities.

    PubMed

    Zhang, Zhijie; Wu, Yunping; Wang, Zhihua; Zou, Xueyan; Zhao, Yanbao; Sun, Lei

    2016-12-01

    Silver nanoparticle-embedded polyvinyl alcohol (PVA) nanofibers were prepared through electrospinning technique, using as antimicrobial agents and surface-enhanced Raman scattering (SERS) substrates. Ag nanoparticles (NPs) were synthesized in liquid phase, followed by evenly dispersing in PVA solution. After electrospinning of the mixed solution at room temperature, the PVA embedded with Ag NPs (Ag/PVA) composite nanofibers were obtained. The morphologies and structures of the as-synthesized Ag nanoparticles and Ag/PVA fibers were characterized by the techniques of transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). Ag NPs have an average diameter of 13.8nm, were found to be uniformly dispersed in PVA nanofibers. The Ag/PVA nanofibers provided robust antibacterial activities against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) microorganisms. It's also found that Ag/PVA nanofibers make a significant contribution to the high sensitivity of SERS to 4-mercaptophenol (4-MPh) molecules. PMID:27612736

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

    SciTech Connect

    King, K.J.

    1988-03-31

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

  10. Isolation and characterization of a novel poly(vinyl alcohol)-degrading bacterium, Sphingopyxis sp. PVA3.

    PubMed

    Yamatsu, Atsushi; Matsumi, Rie; Atomi, Haruyuki; Imanaka, Tadayuki

    2006-10-01

    We have isolated a poly(vinyl alcohol) (PVA)-degrading bacterium from an activated sludge sample obtained from the drainage of a dyeing factory. Enrichment cultures were performed in media containing PVA as the sole or major carbon source. After several rounds of cultivation on liquid and solid media, we were able to isolate a single colony with PVA-degrading ability (strain PVA3). The bacterium could degrade PVA in the absence of symbionts or cofactors such as pyrroloquinoline quinone (PQQ). Over 90% of PVA, at an initial concentration of 0.1%, was degraded within a 6-day cultivation. Degradation was confirmed by both iodometric methods and gel permeation chromatography. Examination of the PVA attached to the cells revealed a large increase in carbonyl groups, suggesting the oxidation of hydroxyl groups of the polymer on the surfaces of cells. Addition of PQQ to the culture medium did not enhance the growth and the PVA-degrading rates of strain PVA3. Furthermore, we found that cells grown on PVA generated hydrogen peroxide upon the addition of PVA. The results strongly suggest that the initial oxidation of PVA is mediated via a PVA oxidase, and not a PQQ-dependent dehydrogenase. A biochemical and phylogenetic characterization of the bacterium was performed. The sequence of the 16S ribosomal RNA gene of the bacterium indicated a phylogenetic position of the strain within the genus Sphingopyxis, and the strain was therefore designated Sphingopyxis sp. PVA3. PMID:16583228

  11. Swelling, mechanical and friction properties of PVA/PVP hydrogels after swelling in osmotic pressure solution.

    PubMed

    Shi, Yan; Xiong, Dangsheng; Liu, Yuntong; Wang, Nan; Zhao, Xiaoduo

    2016-08-01

    The potential of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) hydrogels as articular cartilage replacements was in vitro evaluated by using a macromolecule-based solution to mimic the osmotic environment of cartilage tissue. The effects of osmotic pressure solution on the morphology, crystallinity, swelling, mechanical and friction properties of PVA/PVP hydrogels were investigated by swelling them in non-osmotic and osmotic pressure solutions. The results demonstrated that swelling ratio and equilibrium water content were greatly reduced by swelling in osmotic solution, and the swelling process was found to present pseudo-Fickian diffusion character. The crystallization degree of hydrogels after swelling in osmotic solution increased more significantly when it compared with that in non-osmotic solution. After swelling in osmotic solution for 28days, the compressive tangent modulus and storage modulus of hydrogels were significantly increased, and the low friction coefficient was reduced. However, after swelling in the non-osmotic solution, the compressive tangent modulus and friction coefficient of hydrogels were comparable with those of as-prepared hydrogels. The better material properties of hydrogels in vivo than in vitro evaluation demonstrated their potential application in cartilage replacement. PMID:27157740

  12. Luminescence study of ZnSe/PVA (polyvinyl alcohol) composite film

    NASA Astrophysics Data System (ADS)

    Lahariya, Vikas

    2016-05-01

    The ZnSe nanocrystals have been prepared into poly vinyl alcohol(PVA) polymer matrix on glass using ZnCl2 and Na2SeSO3 as zinc and selenium source respectively. Poly vinyl Alcohol (PVA) used as polymer matrix cum capping agent due to their high viscosity and water solubility. It is transparent for visible region and prevents Se- ions to photo oxidation. The ZnSe/PVA composite film was deposited on glass substrate. The film was characterized by X Ray Diffraction (XRD) and UV-Visible absorption Spectroscopy and Photoluminescence. The X Ray Diffraction (XRD) study confirms the nanometer size (10 nm) particle formation within PVA matrix with cubic zinc blend crystal structure. The UV-Visible Absorption spectrum of ZnSe/PVA composite film shown blue shift in absorption edge indicating increased band gap due to quantum confinement. The calculated energy band gap from the absorption edge using Tauc relation is 3.4eV. From the Photoluminescence study a broad peak at 435 nm has been observed in violet blue region due to recombination of surface states.

  13. Study of parallel oriented electrospun polyvinyl alcohol (PVA) nanofibers using modified electrospinning method

    NASA Astrophysics Data System (ADS)

    Yusuf, Yusril; Ula, Nur Mufidatul; Jahidah, Khannah; Kusumasari, Ervanggis Minggar; Triyana, Kuwat; Sosiati, Harini; Harsojo

    2016-04-01

    Parallel orientedpolyvinyl alcohol (PVA) nanofibershasbeen successfully prepared by using modified electrospinning method. This method uses two pairs of copper (Cu) electrodes which are set apart at a certain distance and applied voltage of 15 kV. The concentrations of PVA were varied from 11%, 13%, 15%, 17%, and 19%. The width of gap collector were varied from 5 mm, 10 mm, 15 mm, and 20 mm. The diameter of nanofibers increase as increasing concentration of PVA. As the width of gap collector increase, first diameter of nanofibers decrease and reach a minimum value at 355 ± 7nm in 15 mm of gap, then the diameters increase again. We also calculated the alignment parameter (S) for given aligned nanofiber. The result showed that alignment parameters (S) were on values around 0,9-1.

  14. 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. PMID:24206353

  15. Modifying Poly(Vinyl Alcohol) (PVA) from Insulator to Small-Bandgap Polymer: A Novel Approach for Organic Solar Cells and Optoelectronic Devices

    NASA Astrophysics Data System (ADS)

    Aziz, Shujahadeen B.

    2016-01-01

    An innovative method has been used to reduce the bandgap of poly(vinyl alcohol) (PVA) polymer by addition of a nontoxic, inexpensive, and environmentally friendly material. The resulting materials are small-bandgap polymers, hence opening new frontiers in green chemistry. The doped PVA films showed a wide range of light absorption of the solar spectrum from 200 nm to above 800 nm. Nonsharp absorption behavior versus wavelength was observed for the samples. The refractive index exhibited a wide range of dispersion. Shift of the absorption edge from 6.2 eV to 1.5 eV was observed. The energy bandgap of PVA was diminished to 1.85 eV upon addition of black tea extract solution, lying in the range of small-bandgap polymers. Increase of the optical dielectric constant was observed with increasing tea solution addition. The results indicate that small-bandgap PVA with good film-forming ability could be useful in terms of cost-performance tradeoff, solving problems of short lifetime, cost, and flexibility associated with conjugated polymers. The decrease of the Urbach energy upon addition of black tea extract solution indicates modification of PVA from a disordered to ordered material. X-ray diffraction results confirm an increase of the crystalline fraction in the doped samples.

  16. Synthesis of fast response crosslinked PVA-g-NIPAAm nanohydrogels by very low radiation dose in dilute aqueous solution

    NASA Astrophysics Data System (ADS)

    Fathi, Marziyeh; Reza Farajollahi, Ali; Akbar Entezami, Ali

    2013-05-01

    Nanohydrogels of poly(vinyl alcohol)-g-N-isopropylacrylamide (PVA-g-NIPAAm) are synthesized by PVA and NIPAAm dilute aqueous solution using much less radiation dose of 1-20 Gy via intramolecular crosslinking at ambient temperature. The radiation synthesis of nanohydrogels is performed in the presence of tetrakis (hydroxymethyl) phosphonium chloride (THPC) due to its rapid oxygen scavenging abilities and hydrogen peroxide (H2O2) as a source of hydroxyl radicals. The effect of radiation dose, feed composition ratio of PVA and H2O2 is investigated on swelling properties such as temperature and pH dependence of equilibrium swelling ratio as well as deswelling kinetics. Experimental data exhibit high equilibrium swelling ratio and fast response time for the synthesized nanohydrogels. The average molecular weight between crosslinks (Mc) and crosslinking density (ρx) of the obtained nanohydrogels are calculated from swelling data as a function of radiation dose, H2O2 and PVA amount. Fourier transform infrared spectroscopy (FT-IR), elemental analysis of nitrogen content and thermogravimetric analysis (TGA) are used to confirm the grafting reaction. Lower critical solution temperature (LCST) is measured around 33 °C by differential scanning calorimetry (DSC) for PVA-g-NIPAAm nanohydrogels. Dynamic light scattering (DLS) data demonstrate that the increase of radiation dose leads to the decreasing in dimension of nanohydrogels. Also, rheological studies are confirmed an improvement in the mechanical properties of the nanohydrogels with increasing the radiation dose. A cytotoxicity study exhibits a good biocompatibility for the obtained nanohydrogels. The prepared nanohydrogels show fast swelling/deswelling behavior, high swelling ratio, dual sensitivity and good cytocompatibility, which may find potential applications as biomaterial.

  17. Study of structural modification of PVA by incorporating Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Saini, Isha; Sharma, Annu; Rozra, Jyoti; Aggarwal, Sanjeev; Dhiman, Rajnish; Sharma, Pawan K.

    2016-05-01

    Nanocomposites of PVA with Ag nanoparticles dispersed in it were synthesized using solution casting method. The morphology and size distribution of Ag nanoparticles embedded in PVA matrix were obtained by transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FE-SEM). Raman spectroscopy was used to examine structural changes taking place inside polyvinyl alcohol (PVA) matrix due to incorporation of Ag nanoparticle. Raman analysis indicates that Ag nanoparticles interact with PVA through H-bonding.

  18. Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

    NASA Astrophysics Data System (ADS)

    Prabhudesai, S. A.; Lawrence, Mathias B.; Mitra, S.; Desa, J. A. E.; Mukhopadhyay, R.

    2015-06-01

    Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D2O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10-5 cm2/sec.

  19. Dynamics in poly vinyl alcohol (PVA) based hydrogel: Neutron scattering study

    SciTech Connect

    Prabhudesai, S. A. Mitra, S.; Mukhopadhyay, R.; Lawrence, Mathias B.; Desa, J. A. E.

    2015-06-24

    Results of quasielastic neutron scattering measurements carried out on Poly Vinyl Alcohol (PVA) based hydrogels are reported here. PVA hydrogels are formed using Borax as a cross-linking agent in D{sub 2}O solvent. This synthetic polymer can be used for obtaining the hydrogels with potential use in the field of biomaterials. The aim of this paper is to study the dynamics of polymer chain in the hydrogel since it is known that polymer mobility influences the kinetics of loading and release of drugs. It is found that the dynamics of hydrogen atoms in the polymer chain could be described by a model where the diffusion of hydrogen atoms is limited within a spherical volume of radius 3.3 Å. Average diffusivity estimated from the behavior of quasielastic width is found to be 1.2 × 10{sup −5} cm{sup 2}/sec.

  20. Effects of silica nanoparticles on copper nanowire dispersions in aqueous PVA solutions

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hak; Song, Hyeong Yong; Hyun, Kyu

    2016-05-01

    In this study, the effects of adding silica nanoparticles to PVA/CuNW suspensions were investigated rheologically, in particular, by small and large amplitude oscillatory shear (SAOS and LAOS) test. Interesting, the SAOS test showed the complex viscosities of CuNW/silica based PVA matrix were smaller than those of PVA/CuNW without silica. These phenomena show that nano-sized silica affects the dispersion of CuNW in aqueous PVA, which suggests small particles can prevent CuNW aggregation. Nonlinearity (third relative intensity ≡ I 3/1) was calculated from LAOS test results using Fourier Transform rheology (FT-rheology) and nonlinear linear viscoelastic ratio (NLR) value was calculated using the nonlinear parameter Q and complex modulus G*. Nonlinearity ( I 3/1) results showed more CuNW aggregation in PVA/CuNW without silica than in PVA/CuNW with silica. NLR (= [ Q 0( ϕ)/ Q 0(0)]/[ G*( ϕ)/ G*(0)]) results revealed an optimum concentration ratio of silica to CuNW to achieve a well-dispersed state. Degree of dispersion was assessed through the simple optical method. SAOS and LAOS test, and dried film morphologies showed nano-sized silica can improve CuNW dispersion in aqueous PVA solutions.

  1. Electrical behavior of polymer hydrogel composed of poly(vinyl alcohol)/hyaluronic acid in solution

    NASA Astrophysics Data System (ADS)

    Kim, Seon Jeong; Yoon, Seoung Gil; Park, Sang Jun; Lee, Chang Kee; Shin, Su Ryon; Lee, Young Moo; Kim, In Young; Kim, Sun I.

    2003-07-01

    Interpenetrating polymer networks (IPN) composed of poly(vinyl alcohol) (PVA) and hyaluronic acid (HA) were prepared and exhibited electrical sensitive behavior. The swelling behavior of the PVA/HA IPN was studied by immersion of the gel in aqueous NaCl solutions at various concentrations and pHs. Also, the stimuli response of the PVA/HA IPN in electric fields was investigated. When swollen IPN was placed between a pair of electrodes, the PVA/HA IPN exhibited bending behavior upon the application of an electric field. The PVA/HA IPN also showed stepwise bending behavior depending on the electric stimulus. Also, for using biomedical application, the bending behavior of PVA/HA IPN has been studied in hank"s solution at pH 7.4

  2. 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. PMID:22325932

  3. 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.

  4. Silver Nanoparticle Fabrication by Laser Ablation in Polyvinyl Alcohol Solutions

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

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

    SciTech Connect

    Oji, L.N.

    2003-08-07

    Photochemical and ultrasonic treatment of polyvinyl alcohol (PVA), derived from PVA fabric material, with hydrogen peroxide was evaluated as a primary method for PVA mineralization into simpler organic molecules. PVA-based waste streams have been found to be compatible with nuclear process wastewater treatment facilities only when solubilized PVA is more than 90 percent mineralized with hydrogen peroxide. No undesirable solid particles are formed with other nuclear process liquid waste when they are mixed, pH adjusted, evaporated and blended with this type of oxidized PVA waste streams. The presence of oxidized PVA in a typical nuclear process wastewater has been found to have no detrimental effect on the efficiency of ion exchange resins, inorganic, and precipitation agents used for the removal of radionuclides from nuclear waste streams. The disappearance of PVA solution in hydrogen peroxide with ultrasonic/ ultraviolet irradiation treatment was characterized by pseudo-first-order reaction kinetics. Radioactive waste contaminated PVA fabric can be solubilized and mineralized to produce processible liquid waste, hence, no bulky solid waste disposal cost can be incurred and the radionuclides can be effectively recovered. Therefore, PVA fabric materials can be considered as an effective substitute for cellulose fabrics that are currently used in radioactive waste decontamination processes.

  6. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties.

    PubMed

    Sousa, Ana M M; Souza, Hiléia K S; Uknalis, Joseph; Liu, Shih-Chuan; Gonçalves, Maria P; Liu, LinShu

    2015-01-22

    In this work, we report the successful fabrication of agar-based nanofibers by electrospinning technique, using water as solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operating at 50°C, to avoid agar gelation. Agar pure solution (1 wt%) showed inadequate spinnability regardless of the used electrospinning conditions. The addition of a co-blending polymer such as PVA (10 wt% starting solution) improved the solutions viscoelasticity and hence, the solutions spinnability. Agar/PVA solutions were prepared with different mass ratios (100/0, 50/50, 40/60, 30/70, 20/80 and 0/100) and electrospun at various sets of electrospinning conditions. Best nanofibers were obtained with 30/70 and 20/80 agar/PVA blends while samples with higher agar contents (50/50 and 40/60 agar/PVA) were harder to process and led to discontinuous fibrous mats. This first set of encouraging results can open a new window of opportunities for agar-based biomaterials in the form of nanofibers. PMID:25439904

  7. Vitamin C hinders radiation cross-linking in aqueous poly(vinyl alcohol) solutions

    NASA Astrophysics Data System (ADS)

    Oral, Ebru; Bodugoz-Senturk, Hatice; Macias, Celia; Muratoglu, Orhun K.

    2007-12-01

    Poly(vinyl alcohol) (PVA) is a promising semi-crystalline material for biomedical applications. It is soluble in water and can be formed into hydrogels by freezing and thawing or crystallizing from an aqueous theta solution such as that of polyethylene glycol (PEG). Radiation cross-linking caused by sterilization or high dose irradiation of concentrated PVA solutions could compromise some properties of these hydrogels. Therefore, we hypothesized that radiation cross-linking of PVA solutions and PVA-PEG theta gels could be prevented by using the antioxidant vitamin C as an anticross-linking agent. Our hypothesis tested positive. Vitamin C concentrations of 0.75 and 4.5 mol/mol of PVA repeating unit could prevent cross-linking in 17.5 wt/v% PVA solutions made with PVA molecular weight of 115,000 g/mol irradiated to 25 and 100 kGy, respectively. Vitamin C also prevented cross-linking in 25 kGy irradiated PVA-PEG theta gels containing up to 5 wt% PEG and decreased the viscosity of those up to 39 wt%.

  8. Electrical Conductivity Study of Polymer Electrolyte Magnetic Nanocomposite Based Poly(Vinyl) Alcohol (PVA) Doping Lithium and Nickel Salt

    NASA Astrophysics Data System (ADS)

    Aji, Mahardika Prasetya; Rahmawati, Silvia, Bijaksana, Satria; Khairurrijal, Abdullah, Mikrajuddin

    2010-10-01

    Composite polymer electrolyte magnetic systems composed of poly(vinyl) alcohol (PVA) as the host polymer, lithium and nickel salt as dopant were studied. The effect upon addition of lithium ions in polimer PVA had been enhanced conductivity with the increase of lithium concentration. The conductivity values were 1.19x10-6, 1.25x10-5, 4.89x-5, 1.88x10-4, and 1.33x10-3 Sṡcm-1 for pure PVA and 1%, 3%, 5% and 7% LiOH complexed PVA, respectively. Meanwhile, the addition nickel salt into polymer electrolyte PVA-LiOH does not significantly change of conductivity value, on order 10-3 Sṡcm-1. The ionic transport is dominantly regarded by Li+ ions present in polymer electrolyte magnetic because the atomic mass Li+ is smaller than Ni2+. The absence of external magnetic field in polimer electrolyte magnetic causes the existence Ni2+ ions not significantly affected of conductivity.

  9. The effects of addition of poly(vinyl) alcohol (PVA) as a green corrosion inhibitor to the phosphate conversion coating on the anticorrosion and adhesion properties of the epoxy coating on the steel substrate

    NASA Astrophysics Data System (ADS)

    Ramezanzadeh, B.; Vakili, H.; Amini, R.

    2015-02-01

    Steel substrates were chemically treated by room temperature zinc phosphate conversion coating. Poly(vinyl) alcohol (PVA) was added to the phosphate solution as a green corrosion inhibitor. Finally, the epoxy/polyamide coating was applied on the untreated and surface treated steel samples. The effects of PVA on the morphological properties of the phosphate coating were studied by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and contact angle measuring device. The adhesion properties of the epoxy coatings applied on the surface treated samples were investigated by pull-off and cathodic delamination tests. Also, the anticorrosion properties of the epoxy coatings were studied by electrochemical impedance spectroscopy (EIS). Results showed that addition of PVA to the phosphate coating increased the population density of the phosphate crystals and decreased the phosphate grain size. The contact angle of the steel surface treated by Zn-PVA was lower than Zn treated one. The corrosion resistance of the epoxy coating was considerably increased on the steel substrate treated by zinc phosphate conversion coating containing PVA. PVA also enhanced the adhesion properties of the epoxy coating to the steel surface and decreased the cathodic delamination significantly.

  10. Investigation on surface molecular conformations and pervaporation performance of the poly(vinyl alcohol) (PVA) membrane.

    PubMed

    Zhang, Wei; Zhang, Zhennan; Wang, Xinping

    2009-05-01

    A simple method of changing pre-treatment temperature in the course of film formation was used to tune the surface structures of PVA membranes. Surface structure and property of the resulting membranes were characterized by X-ray photoelectron spectroscopy (XPS), sum frequency generation (SFG) vibrational spectroscopy, and contact angle measurements. The results show that PVA have different molecular conformations at the membrane surface while those membranes were prepared at different pre-treatment temperature. At higher pre-treatment temperatures, polar acetoxyl residues and hydroxyl groups of the PVA chains oriented in a more orderly fashion, as induced by the faster evaporation of water. When the membranes were in air, CH(3) groups adjacent to the acetoxyl groups covered the surface in order to minimize the surface free energy, while backbones of the PVA were rarely observed. These surfaces exhibited a hydrophilic nature upon contact with water due to rapid surface reconstruction. Conversely, at lower pre-treatment temperatures, the backbone CH(2) groups dominated the surface, forming a less hydrophilic surface. When the PVA membranes were employed to separate ethanol/water mixtures, it was found that the PVA membranes with more hydrophilic surface exhibited higher water selectivity. Our investigation indicates that molecular conformations on the membrane surface have considerable influence on pervaporation performance. PMID:19249794

  11. The effect of poly(vinyl alcohol) on the photophysical properties of pyronin dyes in aqueous solution: A spectroscopic study

    NASA Astrophysics Data System (ADS)

    Gür, Bahri; Meral, Kadem

    2013-01-01

    The photophysical properties of pyronin B (PyB) and pyronin Y (PyY) in water and poly(vinyl alcohol) (PVA) aqueous solutions were studied by using absorption, steady-state fluorescence and time-resolved fluorescence spectroscopy techniques at room temperature. The spectroscopic and photophysical properties of pyronin dyes in the concentrated PVA aqueous solution were different than those found in water. The aggregation of the pyronin dyes in the concentrated PVA aqueous solution was prevented with ease while the dye aggregation was generally formed in water with high dye concentration. The decrease in the aggregation tendency of pyronin dyes in the concentrated PVA aqueous solution caused an increase in radiative transitions. The addition of PVA into the aqueous solution induced the enhancement in the fluorescence intensity of the dyes compared to those in water. As a result, the quantum yields of the dyes were improved by the addition of PVA at high loading. The time-resolved fluorescence study revealed that the fluorescence decay of dyes in all solutions were found to be single-exponential and the fluorescence lifetime of pyronin dyes in the concentrated PVA aqueous solution were also higher than those found in water.

  12. A novel biocompatible conducting polyvinyl alcohol (PVA)-polyvinylpyrrolidone (PVP)-hydroxyapatite (HAP) composite scaffolds for probable biological application.

    PubMed

    Chaudhuri, B; Mondal, B; Ray, S K; Sarkar, S C

    2016-07-01

    We have prepared biocompatible composites of 80wt% polyvinyl alcohol (PVA)-(20wt%) polyvinylpyrrolidone (PVP) blend with different concentrations of bioactive nanohydroxyapatite, Ca10(PO4)6(HO)2 (HAP). The composite films demonstrated maximum effective conductivity (σ∼1.64×10(-4)S/m) and effective dielectric constant (ε∼290) at percolation threshold concentration (∼10wt% HAP) at room temperature. These values of σ and ε are much higher than those of PVA, PVP or HAP. Our preliminary observation indicated excellent biocompatibility of the electrospun fibrous meshes of two of these composites with different HAP contents (8.5 and 5wt% within percolation threshold concentration) using NIH 3T3 fibroblast cell line. Cells viability on the well characterized composite fibrous scaffolds was determined by MTT [3-(4,5-di-methylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay analysis. Enhancement of σ, due to HAP addition, was found to show increased biocompatibility of the fibrous scaffold. Enhanced σ value of the PVA/PVP-HAP composite provided supporting cues for the increased cell viability and biocompatibility of the composite fibrous meshes. Excellent biocompatibility these electrospun composite scaffolds made them to plausible potential candidates for tissue engineering or other biomedical applications. PMID:26998868

  13. Dichromated polyvinyl alcohol (DC-PVA) wet processed for high index modulation

    NASA Astrophysics Data System (ADS)

    Rallison, Richard D.

    1997-04-01

    PVA films have been used as mold releases, strippable coatings, binders for photopolymers and when sensitized with metals and/or dyes they have been used as photoresists, volume HOEs, multiplexed holographic optical memory and real time non destructive holographic testing. The list goes on and includes Slime and birth control. In holography, DC-PVA is a real time photoanisotropic recording material useful for phase conjugation experiments and also a stable long term storage medium needing no processing other than heat. Now we add the capability of greatly increasing the versatility of PVA by boosting the index modulation by almost two orders of magnitude. We can add broadband display and HOE applications that were not possible before. Simple two or three step liquid processing is all that is required to make the index modulation grow.

  14. Water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels

    NASA Astrophysics Data System (ADS)

    Wang, Qingguo; Zhou, Xue; Zeng, Jinxia; Wang, Jizeng

    2016-02-01

    In this paper, the electron beam irradiation technology being more suitable for the industry application is explored to fabricate the acrylic acid (AAc) monomer-grafted polyvinyl alcohol (PVA-g-AAc) hydrogels. ATR-IR spectra of the PVA-g-AAc hydrogels shows an obvious absorption peak of the sbnd Cdbnd O group at 1701 cm-1, indicating that the AAc monomers were grafted onto the PVA macromolecules. This paper also studied some effects of the mass ratio of PVA/AAc, pH of buffer solution and irradiation dosage on the water swelling properties of the electron beam irradiated PVA-g-AAc hydrogels. The water swelling ratio of PVA-g-AAc hydrogels decreases with increased irradiation dosage and mass ratio of PVA/AAc, whereas swelling ratio increases with increased pH of buffer solution and soaking time. The water-swelling behavior of PVA-g-AAc hydrogels occurred easily in an alkaline environment, particularly in a buffer solution with pH 9.2. Both PVA-g-AAc hydrogels (PVA/AAc = 1/5, w/w) irradiated with 5 kilogray (kGy) and PVA-g-AAc hydrogels (PVA/AAc = 1/1, w/w) irradiated with 15 kGy could easily absorb water and lead to high water swelling ratios (up to about 600%), which are potential candidates to meet the requirements for some biomedical applications.

  15. The effect of poly vinyl alcohol (PVA) surfactant on phase formation and magnetic properties of hydrothermally synthesized CoFe2O4 nanoparticles

    NASA Astrophysics Data System (ADS)

    Jalalian, M.; Mirkazemi, S. M.; Alamolhoda, S.

    2016-12-01

    Nanoparticles of CoFe2O4 were synthesized by hydrothermal process at 190 °C with and without poly vinyl alcohol (PVA) addition using treatment durations of 1.5-6 h. The synthesized powders were characterized with X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and vibration sample magnetometer (VSM) techniques. XRD results show presence of CoFe2O4 as the main phase and Co3O4 as the lateral phase in some samples. The results show that in the samples synthesized without PVA addition considerable amount of lateral phase is present after 3 h of hydrothermal treatment while with PVA addition this phase is undetectable in the XRD patterns of the sample synthesized at the same conditions. Microstructural studies represent increasing of particle size with increasing of hydrothermal duration and formation of coarser particles with PVA addition. The highest maximum magnetization (Mmax) values in both of the samples that were synthesized with and without PVA addition are about 59 emu/g that were obtained after 4.5 h of hydrothermal treatment. Intrinsic coercive field (iHc) value of the sample without PVA addition increases from 210 to 430 Oe. While with PVA addition the iHc value changes from 83 Oe to 493 Oe. The mechanism of changes in Mmax and iHc values has been explained.

  16. pH- and sugar-sensitive multilayer films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PBA-PAH) and poly(vinyl alcohol) (PVA): A significant effect of PBA content on the film stability.

    PubMed

    Seno, Masaru; Yoshida, Kentaro; Sato, Katsuhiko; Anzai, Jun-Ichi

    2016-05-01

    Multilayer thin films composed of phenylboronic acid (PBA)-modified poly(allylamine hydrochloride) (PAH), PBA-PAH, with different PBA contents were prepared to study the effect of PBA content on the stability of the films. An alternate deposition of PBA-PAH and poly(vinyl alcohol) (PVA) on the surface of a quartz slide afforded multilayer films through forming boronate ester bonds between PBA-PAH and PVA. The 10-layered (PBA-PAH/PVA)10 films constructed using PBA-PAHs containing 16% and 26% PBA residues were stable in aqueous solutions over the range of pH4.0-10.0, whereas the multilayer films composed of PBA-PAHs with 5.9% and 8.3% PBA decomposed at pH8.0 or lower. The pH-sensitive decomposition of the films was rationalized based on the destabilization of the boronate ester bonds in neutral and acidic solutions. In addition, the (PBA-PAH/PVA)10 films decomposed in glucose and fructose solutions as a result of competitive binding of sugars to PBA-PAH in the films. The sugar response of the films depended on the PBA content in PBA-PAH. The (PBA-PAH/PVA)10 films consisting of 16% and 26% PBA-substituted PBA-PAHs are sensitive to physiological relevant level of glucose at pH7.4 while stable in glucose-free solution, suggesting a potential use of the films in constructing glucose-induced delivery systems. PMID:26952449

  17. 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.

  18. Electrospinning, mechanical properties, and cell behavior study of chitosan/PVA nanofibers.

    PubMed

    Koosha, Mojtaba; Mirzadeh, Hamid

    2015-09-01

    Electrospinning process has been widely used to produce nanofibers from polymer blends. Poly(vinyl alcohol) (PVA) and chitosan (CS) have numerous biomedical applications such as wound healing and tissue engineering. Nanofibers of CS/PVA have been prepared by many works, however, a complete physicochemical and mechanical characterization as well as cell behavior has not been reported. In this study, PVA and CS/PVA blend solutions in acetic acid 70% with different volume ratios (30/70, 50/50, and 70/30) were electrospun in constant electrospinning process parameters. The structure and morphology of nanofibrous mats were characterized by SEM, FTIR, and XRD methods. The best nanofibrous mat was achieved from the CS/PVA 30/70 blend solution regarding the electrospinning throughput. The dynamic mechanical thermal analysis (DMTA) of PVA and CS/PVA 30/70 nanofibrous mats were measured which were not considered in the previous studies. DMTA results in accordance to the DSC analysis approved the partial compatibility between the two polymers, while a single glass transition temperature was not observed for the blend. The tensile strength of PVA and CS/PVA nanofibers were also reported. Results of cell behavior study indicated that the heat stabilized nanofibrous mat CS/PVA 30/70 was able to support the attachment and proliferation of the fibroblast cells. PMID:25727934

  19. Polycondensation kinetics of furfuryl alcohol solutions

    NASA Astrophysics Data System (ADS)

    Zherebtsov, D. A.; Galimov, D. M.; Zagorul'ko, O. V.; Frolova, E. V.; Bol'shakov, O. I.; Zakharov, V. G.; Mikhailov, G. G.

    2016-01-01

    Changes in the viscosity, electrical conductivity, monomer concentration, and the size of growing molecules of polycondensed furfuryl alcohol are studied in solutions containing triethylene glycol and isooctylphenyldecaethylene glycol. The effect the solution compositions have on the condensation kinetics is considered.

  20. Photogeneration of H2O2 in SPEEK/PVA aqueous polymer solutions.

    PubMed

    Little, Brian K; Lockhart, PaviElle; Slaten, B L; Mills, G

    2013-05-23

    Photolysis of air-saturated aqueous solutions containing sulphonated poly(ether etherketone) and poly(vinyl alcohol) results in the generation of hydrogen peroxide. Consumption of oxygen and H2O2 formation are initially concurrent processes with a quantum yield of peroxide generation of 0.02 in stirred or unstirred solutions within the range of 7 ≤ pH ≤ 9. The results are rationalized in terms of O2 reduction by photogenerated α-hydroxy radicals of the polymeric ketone in competition with radical-radical processes that consume the macromolecular reducing agents. Generation of H2O2 is controlled by the photochemical transformation that produces the polymer radicals, which is most efficient in neutral and slightly alkaline solutions. Quenching of the excited state of the polyketone by both H3O(+) and OH(-) affect the yields of the reducing macromolecular radicals and of H2O2. Deprotonation of the α-hydroxy polymeric radicals at pH > 9 accelerate their decay and contribute to suppressing the peroxide yields in basic solutions. Maxima in [H2O2] are observed when illuminations are performed with static systems, where O2 reduction is faster than diffusion of oxygen into the solutions. Under such conditions H2O2 can compete with O2 for the reducing radicals resulting in a consumption of the peroxide. PMID:23654204

  1. Selective permeability of PVA membranes. I - Radiation-crosslinked membranes

    NASA Technical Reports Server (NTRS)

    Katz, M. G.; Wydeven, T., Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  2. Selective Permeability of PVA Membranes. I: Radiation-Crosslinked Membranes

    NASA Technical Reports Server (NTRS)

    Katz, Moshe G.; Wydeven, Theodore, Jr.

    1981-01-01

    The water and salt transport properties of ionizing radiation crosslinked poly(vinyl alcohol) (PVA) membranes were investigated. The studied membranes showed high permeabilities and low selectivities for both water and salt. The results were found to be in accord with a modified solution-diffusion model for transport across the membranes, in which pressure-dependent permeability coefficients are employed.

  3. Solution Spinning and Characterization of Poly (vinyl alcohol) /Soybean Polyblend Fibers

    NASA Astrophysics Data System (ADS)

    Zhang, Xiefei; Kumar, Satish

    2002-03-01

    Solution Spinning and Characterization of Poly (vinyl alcohol) /Soybean Polyblend Fibers Xiefei Zhang and Satish Kumar School of Textile and Fiber Engineering Georgia Institute of Technology Atlanta GA 30032 During 1930s and 40s there was significant research activity in processing fibers from regenerated proteins. However, due to development of synthetic fibers and partially due to low tensile strength of the regenerated protein fibers, there has not been much interest in this field over last half a century. To improve strength of the regenerated protein, an attempt has been made to process PVA /soybean protein polyblend fibers. PVA/Soybean protein ratio of 100/0, 90/10, 70/30, 50/50, 40/60, 20/80 and 0/100 have been utilized. This has been done in an attempt to take advantage of the PVA/soybean interaction. Urea, sodium sulfite, as well as heat, were used to make denatured soybean protein solution, which was suitable for solution spinning. The polyblend fibers underwent post-spinning treatment, such as crosslinking, washing, drying and heat treatment. The fibers have been characterized for thermal behavior and tensile as well as dynamic mechanical properties. Blend fiber morphology was studied using scanning electron microscopy and fiber structure characterized using wide angle X-ray diffraction. Effects of draw ratio, crosslinking time, crosslinking agent, heat treatment conditions as well as PVA/soybean composition on the mechanical properties of polyblend fibers have been studied. Dynamic mechanical analysis as well as scanning electron microscopy exhibit PVA /soybean protein compatibility.

  4. Determining the electrical mechanism of the surface resistivity property of doped polyvinyl alcohol (PVA) and the pyroelectric property of polyvinylidene difluoride (PVDF) thin films

    NASA Astrophysics Data System (ADS)

    Edwards, Matthew; Janen, Afef; Guggilla, Padmaja; Polius, Jemelia; Douglas, Jade; Curley, Michael

    2015-08-01

    Previously, we have reported measurements of the temperature-dependent surface resistivity of pure and multi-walled carbon nanotubes doped Polyvinyl Alcohol (PVA) thin films. In the temperature range from 22 °C to 40 °C, with a humidity-controlled environment, we found the surface resistivity to decrease initially but to rise steadily as the temperature continued to increase. Correspondingly, we have measured the temperature-dependent pyroelectric coefficient of doped polyvinylidene difluoride (PVDF) thin films, very well. While the physical mechanism of the pyroelectric phenomenon in PVDF thin films is quite well known, the surface resistivity behavior of PVA thin films is not so well known. Here, we address this concern by reporting the electrical mechanistic phenomena that contribute to surface resistivity of pure and doped PVA thin films, and give preliminary surface resistivity detectivity and other relevant quality factors for infrared (IR) and motion sensors. Regarding the pyroelectric effect of doped PVDF thin films, we give materials Figures-of-Merit based on our measurements. In addition, pyroelectric and surface resistivity infrared fundamentals, IR sensor uniqueness, and innovative techniques are presented.

  5. PVA/K2Ti6O13 synthetic composite for dielectric applications

    NASA Astrophysics Data System (ADS)

    Pandey, Mayank; Joshi, Girish M.; Khutia, Moumita; Rao, N. Madhusudhana; Kaleemulla, S.; Ramesh Kumar, C.; Cuberes, M. Teresa

    2016-05-01

    We demonstrated the preparation of polyvinyl alcohol (PVA) /Potassium titanate (K2Ti6O13) synthetic composite by solution blending. The loading of K2Ti6O13 well dispersed in PVA and improved electrical performance. The dielectric constant and loss as a function of temperature were recorded under frequency (200Hz-1 kHz). The real dielectric constant value obtained is (ɛ=1000) feasible for various electronic and non-conventional energy applications.

  6. A new fabrication route for PVA/graphene platelets composites with enhanced functionalities

    NASA Astrophysics Data System (ADS)

    Lavecchia, Teresa; Tamburri, Emanuela; Angjellari, Mariglen; Savi, Damiano; Terranova, Maria Letizia

    2016-05-01

    This work deals with the synthesis and characterization of composites made of poly(vinyl alcohol) (PVA) and oxidized graphene platelets obtained from an ad hoc treatment of graphite. The composite is produced by a modified solution mixing procedure in which the in situ crosslinking of PVA with maleic anhydride has been carried out in the presence of the carbon filler. A complete characterization of the material is presented carried out by SEM, DTGA, Raman spectroscopy and I-V characteristics analysis.

  7. Growth of MgO on multi-layered graphene and Mg in PVA matrix

    NASA Astrophysics Data System (ADS)

    Marka, Sandeep K.; Mohiddon, Md. Ahamad; Prasad, Muvva D.; Srikanth, Vadali V. S. S.

    2015-07-01

    An easy and low temperature in-situ growth of MgO micro-rods on multi-layered graphene (MLG) in poly vinyl alcohol (PVA) matrix is elucidated. MLG decked with nanosized fragments of MgO and PVA are used as the starting materials to form MgO micro-rods (width = ∼1 μm and length = ∼4 μm) and MLG filled PVA composite film. Simple solution mixing, spin coating and simple drying processes are used to obtain the PVA composite. The growth mechanism of MgO micro-rods and the role of PVA in the growth of MgO micro-rods are explained on the basis of the observed morphological, structural and phase characteristics and a further controlled synthesis experiment, respectively.

  8. Proton Conducting Polymer Electrolyte Based on Pva-Pan

    NASA Astrophysics Data System (ADS)

    Devi, S. Siva; Selvasekarapandian, S.; Rajeswari, N.; Genova, F. Kingslin Mary; Karthikeyan, S.; Raja, C. Sanjeevi

    2013-07-01

    Proton conducting polymer electrolytes based on blend polymer using Poly Vinyl Alcohol (PVA) and Poly Acrylo Nitrile (PAN) doped with ammonium nitrate have been prepared by solution casting method. The highest conductivity at room temperature (305K) has been found to be 1.8×10-3 S cm-1 for 15 mole % NH4NO3 doped PVA-PAN system. X ray Diffraction pattern of the doped and the undoped blend polymer electrolyte confirms the amorphous nature of blend polymer, when salt is added. The complex formation between the blend polymer and the salt has been confirmed by Fourier transform infrared spectroscopy.

  9. Anomalous dielectric behaviour of poly(vinyl alcohol)-silicon dioxide (PVA-SiO2) nanocomposites

    NASA Astrophysics Data System (ADS)

    Choudhary, Shobhna; Sengwa, R. J.

    2016-05-01

    Complex dielectric function, electric modulus, ac conductivity and impedance spectra of PVA-SiO2 nanocomposite films have been investigated in the frequency range of 20 Hz to 1 MHz and temperature range from 30 °C to 60 °C. Real part of dielectric function of the nanocomposites slowly decreases with increase of frequency and it shows a non-linear increase with the increase of temperature. An anomalous variation is observed in dielectric and electrical functions with increase of SiO2 concentrations in the PVA matrix. The ac conductivity of these materials increases whereas impedance values decrease linearly by five orders of magnitude with increase of frequency from 20 Hz to 1 MHz. Dielectric loss values of these films are found minimum at intermediate frequency region, and it increases at low and high frequency regions confirming the presence of multiple relaxation processes. The contributions of interfacial polarization effect and dipolar ordering in dielectric properties of these materials have been explored, and their technological applications as nanodielectrics have been discussed. The XRD patterns reveal that the interactions between PVA and SiO2 disturb the dipolar ordering resulting decrease of crystallinity of the PVA in the nanocomposites.

  10. Fabrication of electrospun almond gum/PVA nanofibers as a thermostable delivery system for vanillin.

    PubMed

    Rezaei, Atefe; Tavanai, Hossein; Nasirpour, Ali

    2016-10-01

    In this study, the fabrication of vanillin incorporated almond gum/polyvinyl alcohol (PVA) nanofibers through electrospinning has been investigated. Electrospinning of only almond gum was proved impossible. It was found that the aqueous solution of almond gum/PVA (80:20, concentration=7% (w/w)) containing 3% (w/w) vanillin could have successfully electrospun to uniform nanofibers with diameters as low as 77nm. According to the thermal analysis, incorporated vanillin in almond gum/PVA nanofibers showed higher thermal stability than free vanillin, making this composite especially suitable for high temperature applications. XRD and FTIR analyses proved the presence of vanillin in the almond gum/PVA nanofibers. It was also found that vanillin was dispersed as big crystallites in the matrix of almond gum/PVA nanofibers. FTIR analysis showed almond gum and PVA had chemical cross-linking by etheric bonds between COH groups of almond gum and OH groups of PVA. Also, in the nanofibers, there were no major interaction between vanillin and either almond gum or PVA. PMID:27267574

  11. Construction of chitin/PVA composite hydrogels with jellyfish gel-like structure and their biocompatibility.

    PubMed

    He, Meng; Wang, Zhenggang; Cao, Yan; Zhao, Yanteng; Duan, Bo; Chen, Yun; Xu, Min; Zhang, Lina

    2014-09-01

    High strength chitin/poly(vinyl alcohol) (PVA) composite hydrogels (RCP) were constructed by adding PVA into chitin dissolved in a NaOH/urea aqueous solution, and then by cross-linking with epichlorohydrin (ECH) and freezing-thawing process. The RCP hydrogels were characterized by field emission scanning electron microscopy, FTIR, differential scanning calorimetry, solid-state (13)C NMR, wide-angle X-ray diffraction, and compressive test. The results revealed that the repeated freezing/thawing cycles induced the bicrosslinked networks consisted of chitin and PVA crystals in the composite gels. Interestingly, a jellyfish gel-like structure occurred in the RCP75 gel with 25 wt % PVA content in which the amorphous and crystalline PVA were immobilized tightly in the chitin matrix through hydrogen bonding interaction. The freezing/thawing cycles played an important role in the formation of the layered porous PVA networks and the tight combining of PVA with the pore wall of chitin. The mechanical properties of RCP75 were much higher than the other RCP gels, and the compressive strength was 20× higher than that of pure chitin gels, as a result of broadly dispersing stress caused by the orderly multilayered networks. Furthermore, the cell culture tests indicated that the chitin/PVA composite hydrogels exhibited excellent biocompatibility and safety, showing potential applications in the field of tissue engineering. PMID:25077674

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

    PubMed

    Hoskins, Daniel L; Zhang, Xiaoyuan; Hickner, Michael A; Logan, Bruce E

    2014-11-01

    Separators are used to protect cathodes from biofouling and to avoid electrode short-circuiting, but they can adversely affect microbial fuel cell (MFC) performance. A spray method was used to apply a polyvinyl alcohol (PVA) separator to the cathode. Power densities were unaffected by the PVA separator (339±29mW/m(2)), compared to a control lacking a separator in a low conductivity solution (1mS/cm) similar to wastewater. Power was reduced with separators in solutions typical of laboratory tests (7-13mS/cm), compared to separatorless controls. The PVA separator produced more power in a separator assembly (SEA) configuration (444±8mW/m(2)) in the 1mS/cm solution, but power was reduced if a PVA or wipe separator was used in higher conductivity solutions with either Pt or activated carbon catalysts. Spray and cast PVA separators performed similarly, but the spray method is preferred as it was easier to apply and use. PMID:25260178

  13. One-step synthesis of size-tunable Ag nanoparticles incorporated in electrospun PVA/cyclodextrin nanofibers.

    PubMed

    Celebioglu, Asli; Aytac, Zeynep; Umu, Ozgun C O; Dana, Aykutlu; Tekinay, Turgay; Uyar, Tamer

    2014-01-01

    One-step synthesis of size-tunable silver nanoparticles (Ag-NP) incorporated into electrospun nanofibers was achieved. Initially, in situ reduction of silver salt (AgNO3) to Ag-NP was carried out in aqueous solution of polyvinyl alcohol (PVA). Here, PVA was used as reducing agent and stabilizing polymer as well as electrospinning polymeric matrix for the fabrication of PVA/Ag-NP nanofibers. Afterwards, hydroxypropyl-beta-cyclodextrin (HPβCD) was used as an additional reducing and stabilizing agent in order to control size and uniform dispersion of Ag-NP. The size of Ag-NP was ∼8 nm and some Ag-NP aggregates were observed for PVA/Ag-NP nanofibers, conversely, the size of Ag-NP decreased from ∼8 nm down to ∼2 nm within the fiber matrix without aggregation were attained for PVA/HPβCD nanofibers. The PVA/Ag-NP and PVA/HPβCD/Ag-NP nanofibers exhibited surface enhanced Raman scattering (SERS) effect. Moreover, antibacterial properties of PVA/Ag-NP and PVA/HPβCD/Ag-NP nanofibrous mats were tested against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. PMID:24274573

  14. Mechanically stable antimicrobial chitosan-PVA-silver nanocomposite coatings deposited on titanium implants.

    PubMed

    Mishra, Sandeep K; Ferreira, J M F; Kannan, S

    2015-05-01

    Bionanocomposite coatings with antimicrobial activity comprising polyvinyl alcohol (PVA)-capped silver nanoparticles embedded in chitosan (CS) matrix were developed by a green soft chemistry synthesis route. Colloidal sols of PVA-capped silver nanoparticles (AgNPs) were synthesized by microwave irradiating an aqueous solution comprising silver nitrate and PVA. The bionanocomposites were prepared by adding an aqueous solution of chitosan to the synthesized PVA-capped AgNPs sols in appropriate ratios. Uniform bionanocomposite coatings with different contents of PVA-capped AgNPs were deposited onto titanium substrates by "spread casting" followed by solvent evaporation. Nanoindentation and antimicrobial activity tests performed on CS and bionanocomposites revealed that the incorporation of PVA-capped AgNPs enhanced the overall functional properties of the coatings, namely their mechanical stability and bactericidal activity against Escherichia coli and Staphylococcus aureus. The coated specimens maintained their antimicrobial activity for 8h due to the slow sustained release of silver ions. The overall benefits for the relevant functional properties of the coatings were shown increase with increasing contents of PVA-capped AgNPs in the bionanocomposites. PMID:25659669

  15. Mechanisms of diphylline release from dual-solute loaded poly(vinyl alcohol) matrices.

    PubMed

    Hasimi, Albana; Papadokostaki, Kyriaki G; Sanopoulou, Merope

    2014-01-01

    The release kinetics of the model hydrophilic drug, diphylline (DPL), from physically crosslinked poly(vinyl alcohol) (PVA) matrices, is studied in relation to the drug load and the presence of a second solute incorporated in the matrix. The second solute, a gadolinium (III) complex (Gd-DTPA), is a commonly used MRI contrast agent. The water uptake kinetics by the glassy PVA matrix was found to deviate from t(1/2) law and to occur on time scales comparable to those of diphylline release. The corresponding rate of diphylline release was found to be substantially stabilized as compared to a purely diffusion-controlled release process, in line with theoretical predictions under conditions of relaxation-controlled water uptake kinetics. The release rate of DPL was found (i) to increase with increasing DPL load and (ii) for a particular DPL load, to increase in the presence of Gd-DTPA, incorporated in the matrix. The results were interpreted on the basis of the diphylline-induced plasticization of the polymer (evidenced by the depression of Tg) and of the excess hydration of the matrix at high solute loads. The latter effect was found to be additive in the case of dual-solute loaded matrices. PMID:24268271

  16. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work, we report the successful fabrication of agar-based nanofibers by an electrospinning technique using water as the solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operated at 50 deg C, to avoid agar gelation. Pure agar solution 1% (w/w) showed inadequ...

  17. Surface functionalized magnetic PVA microspheres for rapid naked-eye recognizing of copper(II) ions in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Hua, Zulin; Yang, Bei; Chen, Wei; Bai, Xue; Xu, Quanjun; Gu, Haixin

    2014-10-01

    We proposed a robust method for surface-functionalizing magnetic polyvinyl alcohol microspheres to detect heavy metal ions in aqueous solutions. The prepared chemosensor (PAR-MPVA) was characterized through scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectra (XPS). In neutral solutions, PAR-MPVA selectively recognized diatomic heavy metal ions, as indicated with a color change from earth yellow to red; in strong acidic solutions, the chemosensor only selectively detected Cu2+. PAR-MPVA microspheres had a detection limit as low as 0.5 μM by naked-eye and 0.16 μM by UV-vis spectrometer for Cu2+. Moreover, the sensor possessed magnetism for effective recovery, could easily be regenerated by a solution of EDTA, and also displayed perferable stability. The PAR-MPVA microspheres possessed preeminent properties of detecting copper (II) ions in aqueous solutions.

  18. 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. PMID:27433669

  19. 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.

  20. Preparation and characterization of chitosan/gelatin/PVA hydrogel for wound dressings.

    PubMed

    Fan, Lihong; Yang, Huan; Yang, Jing; Peng, Min; Hu, Jin

    2016-08-01

    Chitosan (CS)/gelatin (Gel)/polyvinyl alcohol (PVA) hydrogels were prepared by the gamma irradiation method for usage in wound dressing applications. Chitosan and gelatin solution was mixed with poly(vinyl alcohol) (PVA) solution at different weight ratios of CS/Gel of 1:3, 1:2, 1:1, 2:1 and 3:1. The hydrogels irradiated at 40kGy. The structure of the hydrogels was characterized by using FT-IR and SEM. The CS/Gel/PVA hydrogels were characterized for physical properties and blood clotting activity. The tensile strength of CS/Gel/PVA hydrogel enhanced than on the basis of the Gel/PVA hydrogel. The highest tensile strength reached the 2.2Mpa. All hydrogels have shown a good coagulation effect. It takes only 5min for the BCI index to reached 0.032 only 5min when the weight ratio of CS/Gel was 1:1. It means that the hemostatic effect of hydrogels were optimal. And the hydrogrls also showed good pH-sensitivity, swelling ability and water evaporation rate. Therefore, this hydrogel showed a promising potential to be applied as wound dressing. PMID:27112893

  1. Solution thermodynamics for alkoxy phenols in alcohol and in water-alcohol systems

    SciTech Connect

    Beezer, A.E.; Hunter, W.H.; Lima, M.C.P.; Volpe, P.L.O.

    1986-04-01

    Solubilities have been measured for m-alkoxyphenols in water-alcohol mixtures. The alcohols ranged from the co-solvent methanol to the co-solute 1-octanol, and each alcohol was present at the saturating concentration of 1-octanol in water viz. 0.00316M. Plots of solubility vs. carbon number of the alcohols show discontinuities. Enthalpies of solution in these same solvent systems have also been measured. The enthalpies of solution and the derived enthalpies of transfer both support the observations on solubilities. The results are discussed on the basis of solvent-solute interactions and in terms of solute volumes.

  2. Hydrothermal growth of NiSe 2 tubular microcrystals assisted by PVA

    NASA Astrophysics Data System (ADS)

    Fan, Hai; Zhang, Maofeng; Zhang, Xianwen; Qian, Yitai

    2009-10-01

    NiSe 2 tubular microcrystals assembled of nanoparticles have been prepared via a hydrothermal method in an ethanolamine and water mixed solution assisted by polyvinyl alcohol (PVA). The prepared tubular crystals with hexagonal structure are composed of nanoparticles with average diameter of 30 nm. It was found that the phase of the products could be adjusted by the molar ratio of the reactants (Ni/Se), and the morphology of the products could be greatly influenced by the quantity of surfactant PVA. Based on the experimental results, the possible formation mechanism of NiSe 2 tubular microcrystals is also discussed.

  3. 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.

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

    PubMed

    Tsujiyama, S; Okada, A

    2013-11-01

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

  5. Mechanical and dielectric properties of carbon nanotubes/poly (vinyl alcohol) nanocomposites

    NASA Astrophysics Data System (ADS)

    Amrin, Sayed; Deshpande, V. D.

    2016-05-01

    In this work, two series of nanocomposites of poly(vinyl alcohol) (PVA) incorporated with multiwalled carbon nanotubes (MWNT) and carboxyl functionalized multiwalled carbon nanotubes (MWNT-COOH) were fabricated using solution-cast method and their tensile and dielectric properties were studied. Tensile tests were carried out on composite films of MWNT/PVA and MWNT-COOH/PVA for different loading levels. Results show that overall mechanical properties of the MWNT-COOH/PVA composite was greatly improved as compared to the MWNT/PVA film. The dielectric properties of nanocomposites were investigated in a frequency range from 0.1Hz to 10MHz at room temperature respectively. Compared to MWNT/PVA composites, higher dielectric constant and ac conductivity was achieved in MWNT-COOH/PVA nanocomposite, which can be well explained by the interfacial polarization effect.

  6. Separation and concentration of lower alcohols from dilute aqueous solutions

    DOEpatents

    Moore, Raymond H.; Eakin, David E.; Baker, Eddie G.; Hallen, Richard T.

    1991-01-01

    A process for producing, from a dilute aqueous solution of a lower (C.sub.1 -C.sub.5) alcohol, a concentrated liquid solution of the alcohol in an aromatic organic solvent is disclosed. Most of the water is removed from the dilute aqueous solution of alcohol by chilling sufficiently to form ice crystals. Simultaneously, the remaining liquid is extracted at substantially the same low temperature with a liquid organic solvent that is substantially immiscible in aqueous liquids and has an affinity for the alcohol at that temperature, causing the alcohol to transfer to the organic phase. After separating the organic liquid from the ice crystals, the organic liquid can be distilled to enrich the concentration of alcohol therein. Ethanol so separated from water and concentrated in an organic solvent such as toluene is useful as an anti-knock additive for gasoline.

  7. Adsorption and photocatalytic degradation of anionic dyes on Chitosan/PVA/Na-Titanate/TiO2 composites synthesized by solution casting method.

    PubMed

    Habiba, Umma; Islam, Md Shariful; Siddique, Tawsif A; Afifi, Amalina M; Ang, Bee Chin

    2016-09-20

    Chitosan/PVA/Na-titanate/TiO2 composite was synthesized by solution casting method. The composite was analyzed via Fourier Transform Infrared Spectroscopy, X-ray diffraction, Field Emission Scanning Electron Microscopy, Thermal gravimetric analysis and water stability test. Incorporation of Na-titanate shown decrease of crystallinity for chitosan but increase water stability. However, the composite structure was deteriorated with considerable weight loss in acidic medium. Two anionic dyes, methyl orange and congo red were used for the adsorption test. The adsorption behavior of the composites were described by pseudo-second-order kinetic model and Lagergren-first-order model for methyl orange and congo red, respectively. For methyl orange, adsorption was started with a promising decolorization rate. 99.9% of methyl orange dye was removed by the composite having higher weightage of chitosan and crystalline TiO2 phase. On the other hand, for the congo red the composite having higher chitosan and Na-titanate showed an efficient removal capacity of 95.76%. UV-vis results showed that the molecular backbone of methyl orange and congo red was almost destroyed when equilibrium was obtained, and the decolorization rate was reaching 100%. Kinetic study results showed that the photocatalytic degradation of methyl orange and congo red could be explained by Langmuir-Hinshelwood model. Thus, chitosan/PVA/Na-titanate/TiO2 possesses efficient adsorptivity and photocatalytic property for dye degradation. PMID:27261756

  8. AC conductivity and electrochemical studies of PVA/PEG based polymer blend electrolyte films

    NASA Astrophysics Data System (ADS)

    Polu, Anji Reddy; Kumar, Ranveer; Dehariya, Harsha

    2012-06-01

    Polymer blend electrolyte films based on Polyvinyl alcohol(PVA)/Poly(ethylene glycol)(PEG) and magnesium nitrate (Mg(NO3)2) were prepared by solution casting technique. Conductivity in the temperature range 303-373 K and transference number measurements have been employed to investigate the charge transport in this polymer blend electrolyte system. The highest conductivity is found to be 9.63 × 10-5 S/cm at 30°C for sample with 30 weight percent of Mg(NO3)2 in PVA/PEG blend matrix. Transport number data shows that the charge transport in this polymer electrolyte system is predominantly due to ions. Using this electrolyte, an electrochemical cell with configuration Mg/(PVA+PEG+Mg(NO3)2)/(I2+C+electrolyte) was fabricated and its discharge characteristics profile has been studied.

  9. Hand antiseptics: rubs versus scrubs, alcoholic solutions versus alcoholic gels.

    PubMed

    Pietsch, H

    2001-08-01

    This report describes three different investigations undertaken to demonstrate the advantage of fluid alcoholic hand disinfectants. In the first study, the skin compatibility of Sterillium, a liquid alcoholic rub-in hand disinfectant was compared with that of Hibiscrub, a water-based handwashing antiseptic. Using various parameters such as image analysis of removed squames (D-squames), skin roughness or transepidermal water loss, Hibiscrub was found to be significantly inferior to Sterillium. Hibiscrub caused skin irritation in 15 volunteers who could not complete the test. In a second study, the microbicidal efficacy of Sterillium and Hibiscrub was tested in surgical hand disinfection. The microbial reduction by Sterillium was significantly greater than that of Hibiscrub, immediately after application as well as after the surgical procedure. In a third study, certain alcoholic gels were tested according to the EN 1500 'hygienic hand disinfection'. None of the gels tested passed the EN 1500 within 30s. However, Sterillium met the EN 1500 requirement within 30s. We conclude that Sterillium is superior to Hibiscrub in terms of skin tolerance and microbicidal efficacy in surgical hand disinfection. It is also superior to alcoholic gels. PMID:11759022

  10. Study of Dielectric Behavior and Charge Conduction Mechanism of Poly(Vinyl Alcohol) (PVA)-Copper (Cu) and Gold (Au) Nanocomposites as a Bio-resorbable Material for Organic Electronics

    NASA Astrophysics Data System (ADS)

    Mahendia, Suman; Goyal, Parveen Kumar; Tomar, Anil Kumar; Chahal, Rishi Pal; Kumar, Shyam

    2016-06-01

    Poly(vinyl alcohol) (PVA) embedded with varying concentrations of chemically synthesized copper (Cu) and gold (Au) nanoparticles (NPs) were prepared using ex situ sol-gel casting method. The addition of almost the same concentration of CuNPs in PVA improves the conducting properties, while that of AuNPs improves the dielectric nature of composite films. It has been found that addition of AuNPs up to ˜0.4 wt.% concentration enhaneces the capacitive nature due to the formation of small Coulomb tunneling knots as internal capacitors. The dielectric studies suggest the Maxwell-Wagner interfacial polarization as the dominant dielectric relaxation process, whereas the I-V characteristics indicate bulk limited Poole-Frenkel emission at high voltages as the dominant charge transport mechanism operating at room temperature in all specimens. These novel features lead to the conclusion that addition of a small quantity of metal nanoparticles can help tune the properties of PVA for desired applications in bio-compatible polymer-based organic electronic devices.

  11. Pervaporation separation of aqueous alcohol solution through asymmetric polycarbonate membrane

    SciTech Connect

    Lee, K.R.; Liu, M.J.; Lai, J.Y. )

    1994-01-01

    In the present work the separation of aqueous alcohol mixtures through wet-phase inversion prepared polycarbonate membranes was studied by using the pervaporation process. The formation of asymmetric pervaporation membranes was discussed in terms of the presence of a nonsolvent in the casting solution, the polycarbonate concentration, and the kinds of coagulation media. The effects of feed composition, swelling degree, and the size of the alcohols on the pervaporation performances were investigated. The rate of liquid-liquid demixing increases with a decreasing number of carbon atoms of the alcohol coagulation medium. The permeation rate of the pervaporation process for the nonsolvent-added membrane was much higher than that of the membrane without nonsolvent additive. In binary alcohol mixtures, the permselectivities of small-sized alcohols through the asymmetric membrane are decided by two factors: preferential solubility of larger-sized alcohol and predominant diffusivity of small-sized alcohol. 19 refs., 8 figs., 6 tabs.

  12. Adsorption of anionic and cationic dyes by activated carbons, PVA hydrogels, and PVA/AC composite.

    PubMed

    Sandeman, Susan R; Gun'ko, Vladimir M; Bakalinska, Olga M; Howell, Carol A; Zheng, Yishan; Kartel, Mykola T; Phillips, Gary J; Mikhalovsky, Sergey V

    2011-06-15

    The textural and adsorption characteristics of a series of activated carbons (ACs), porous poly(vinyl alcohol) (PVA) gels, and PVA/AC composites were studied using scanning electron microscopy, mercury porosimetry, adsorption of nitrogen (at 77.4 K), cationic methylene blue (MB), anionic methyl orange (MO), and Congo red (CR) from the aqueous solutions. Dye-PVA-AC-water interactions were modeled using the semiempirical quantum chemical method PM6. The percentage of dye removed (C(rem)) by the ACs was close to 100% at an equilibrium concentration (C(eq)) of less than 0.1 mM but decreased with increasing dye concentration. This decrease was stronger at C(eq) of less than 1 mM, and C(rem) was less than 50% at a C(eq) of 10-20 mM. For PVA and the PVA/AC composite containing C-7, the C(rem) values were minimal (<75%). The free energy distribution functions (f(ΔG)) for dye adsorption include one to three peaks in the -ΔG range of 1-60 kJ/mol, depending on the dye concentration range used and the spatial, charge symmetry of the hydrated dye ions and the structural characteristics of the adsorbents. The f(ΔG) shape is most complex for MO with the most asymmetrical geometry and charge distribution and adsorbed at concentrations over a large C(eq) range. For symmetrical CR ions, adsorbed over a narrow C(eq) range, the f(ΔG) plot includes mainly one narrow peak. MB has a minimal molecular size at a planar geometry (especially important for effective adsorption in slit-shaped pores) which explains its greater adsorptive capacity over that of MO or CR. Dye adsorption was greatest for ACs with the largest surface area but as molecular size increases adsorption depends to a greater extent on the pore size distribution in addition to total and nanopore surface areas and pore volume. PMID:21457992

  13. Multifunctional electroactive electrospun nanofiber structures from water solution blends of PVA/ODA–MMT and poly(maleic acid-alt-acrylic acid): effects of Ag, organoclay, structural rearrangement and NaOH doping factors

    NASA Astrophysics Data System (ADS)

    Şimşek, Murat; Rzayev, Zakir M. O.; Bunyatova, Ulviya

    2016-06-01

    Novel multifunctional colloidal polymer nanofiber electrolytes were fabricated by green reactive electrospinning nanotechnology from various water solution/dispersed blends of poly (vinyl alcohol-co-vinyl acetate) (PVA)/octadecyl amine-montmorillonite (ODA–MMT) as matrix polymer nanocomposite and poly(maleic acid-alt-acrylic acid) (poly(MAc-alt-AA) and/or its Ag-carrying complex as partner copolymers. Polymer nanofiber electrolytes were characterized using FTIR, XRD, thermal (DSC, TGA–DTG), SEM, and electrical analysis methods. Effects of partner copolymers, organoclay, in situ generated silver nanoparticles (AgNPs), and annealing procedure on physical and chemical properties of polymer composite nanofibers were investigated. The electrical properties (resistance, conductivity, activation energy) of nanofibers with/without NaOH doping agent were also evaluated. This work presented a structural rearrangement of nanofiber mats by annealing via decarboxylation of anhydride units with the formation of new conjugated double bond sites onto partner copolymer main chains. It was also found that the semiconductor behaviors of nanofiber structures were essentially improved with increasing temperature and fraction of partner copolymers as well as presence of organoclay and AgNPs in nanofiber composite.

  14. Livestock air treatment using PVA-coated powdered activated carbon biofilter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The efficacy of polyvinyl alcohol (PVA) biofilters was studied using bench-scale biofilters and air from aerobically-treated swine manure. The PVA-coated powdered activated carbon particles showed excellent properties as a biofiltration medium: water holding capacity of 1.39 g H2O/g-dry PVA; wet por...

  15. Development of functionalized hydroxyapatite/poly(vinyl alcohol) composites

    NASA Astrophysics Data System (ADS)

    Stipniece, Liga; Salma-Ancane, Kristine; Rjabovs, Vitalijs; Juhnevica, Inna; Turks, Maris; Narkevica, Inga; Berzina-Cimdina, Liga

    2016-06-01

    Based on the well-known pharmaceutical excipient potential of poly(vinyl alcohol) (PVA) and clinical success of hydroxyapatite (HAp), the objective of this work was to fabricate functionalized composite microgranules. PVA was modified with succinic anhydride to introduce carboxyl groups (-COOH), respectively, by reaction between the -OH groups of PVA and succinic anhydride, for attachment of drug molecules. For the first time, the functionalized composite microgranules containing HAp/PVA in the ratio of 1:1 were prepared through in situ precipitation of HAp in modified PVA aqueous solutions followed by spray drying of obtained suspensions. The microgranules were characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and differential scanning calorimetry (DSC). The presence of -COOH groups was verified by FT-IR, and the amount of functional groups added to PVA molecules (averaging 15 mol%) was determined by nuclear magnetic resonance spectroscopy (NMR). DSC results showed that modification with -COOH groups slightly decreased the thermal stability of PVA. FT-IR and XRD analysis confirmed that the resulting composites contain mainly nanocrystalline HAp and PVA. Moreover, the images taken by FE-SEM revealed that the microgranules consisted of nanosized HAp crystallites homogenously embedded in the PVA matrix. DSC measurements indicated that decomposition mechanism of the HAp/PVA differs from that of pure PVA and occurs at lower temperatures. However, the presence of HAp had minor influence on the thermal decomposition of the PVA modified with succinic anhydride. The investigation of composite microgranules confirmed interaction and integration between the HAp and PVA.

  16. Extracting alcohols from aqueous solutions. [USDOE patent application

    DOEpatents

    Compere, A.L.; Googin, J.M.; Griffith, W.L.

    1981-12-02

    The objective is to provide an efficient process for extracting alcohols in aqueous solutions into hydrocarbon fuel mixtures, such as gasoline, diesel fuel and fuel oil. This is done by contacting an aqueous fermentation liquor with a hydrocarbon or hydrocarbon mixture containing carbon compounds having 5-18 carbon atoms, which may include gasoline, diesel fuel or fuel oil. The hydrocarbon-aqueous alcohol solution is then mixed with one or more of a group of polyoxyalkylene polymers to extract the alcohol into the hydrocarbon fuel-polyoxyalkylene polymer mixture.

  17. Engineering a Highly Hydrophilic PVDF Membrane via Binding TiO₂Nanoparticles and a PVA Layer onto a Membrane Surface.

    PubMed

    Qin, Aiwen; Li, Xiang; Zhao, Xinzhen; Liu, Dapeng; He, Chunju

    2015-04-29

    A highly hydrophilic PVDF membrane was fabricated through chemically binding TiO2 nanoparticles and a poly(vinyl alcohol) (PVA) layer onto a membrane surface simultaneously. The chemical composition of the modified membrane surface was determined by X-ray photoelectron spectroscopy, and the binding performance of TiO2 nanoparticles and the PVA layer was investigated by a rinsing test. The results indicated that the TiO2 nanoparticles were uniformly and strongly tailored onto the membrane surface, while the PVA layer was firmly attached onto the surface of TiO2 nanoparticles and the membrane by adsorption-cross-linking. The possible mechanisms during the modification process and filtration performance, i.e., water permeability and bovine serum albumin (BSA) rejection, were investigated as well. Furthermore, antifouling property was discussed through multicycles of BSA solution filtration tests, where the flux recovery ratio was significantly increased from 20.0% for pristine PVDF membrane to 80.5% for PVDF/TiO2/PVA-modified membrane. This remarkable promotion is mainly ascribed to the improvement of surface hydrophilicity, where the water contact angle of the membrane surface was decreased from 84° for pristine membrane to 24° for PVDF/TiO2/PVA membrane. This study presents a novel and varied strategy for immobilization of nanoparticles and PVA layer on substrate surface, which could be easily adapted for a variety of materials for surface modification. PMID:25806418

  18. X-ray photoelectron spectroscopy studies of bond structure between polyvinyl alcohol and a titanate cross-coupling agent

    SciTech Connect

    Guelguen, M.A.; Popoola, O.O.; Kriven, W.M.

    1995-06-01

    Chemical interactions between polyvinyl alcohol (PVA) and triethanol amine titanate chelate were studied using x-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The titanate chelate cross coupled the PVA solution and produced a viscous gel. The gel had a three- dimensional network structure containing --C{sub PVA}--O--Ti--O--C{sub PVA}--organic complexes. A new C(1{ital s}) signature at 285.7 eV and an O(1{ital s}) signature at 531.25 eV were associated with the formation of these complexes. The water of the PVA solution was physically retained in the gelled structure and was readily available for chemical reactions. The removal of this entrapped water was irreversible and lead to a collapsed film of Ti-cross-linked PVA.

  19. Preparation and characterization of wet spun silk fibroin/poly(vinyl alcohol) blend filaments.

    PubMed

    Lee, Ki Hoon; Baek, Doo Hyun; Ki, Chang Seok; Park, Young Hwan

    2007-07-01

    Silk fibroin (SF)/poly(vinyl alcohol) (PVA) blend filaments were prepared by a wet spinning process. Regenerated SF and PVA were dissolved in formic acid and the dope solution exhibited good fiber formation in a methanol coagulation bath. Due to the miscibility of SF/PVA in formic acid, the filament had a smooth surface and dense structure with a circular cross-section. The crystalline structure and thermal properties were varied with different SF/PVA ratios. The mechanical properties of the filament were also controlled by blending PVA with SF. Especially, the knot strength of the SF filament, which is a very important suture property, could be significantly improved by blending with PVA. PMID:17324454

  20. Adsorption of thorium(IV) from simulated radioactive solutions using a novel electrospun PVA/TiO2/ZnO nanofiber adsorbent functionalized with mercapto groups: Study in single and multi-component systems

    NASA Astrophysics Data System (ADS)

    Alipour, Dariush; Keshtkar, Ali Reza; Moosavian, Mohammad Ali

    2016-03-01

    The novel polyvinyl alcohol/titanium oxide/zinc oxide (PVA/TiO2/ZnO) nanofiber adsorbent functionalized with 3-mercaptopropyltrimethoxysilane (TMPTMS) was prepared by electrospinning method and its potential was investigated for the adsorption of thorium from single and multi-metal aqueous solutions. The prepared adsorbent was characterized by FTIR, SEM and BET analysis. The influences of different operational parameters such as pH, ionic strength, equilibrium time, initial concentration and temperature were studied in batch mode. Investigation of ionic strength effect showed that the addition of NaNO3 to metal solution has a slight effect on the thorium adsorption, whereas pH value has a serious effect on the thorium adsorption at pH values lower than 4. The double-exponential model described the adsorption of Th(IV) ions much better than other kinetic models within both the single and multi-component systems. Among various isotherm models used, the equilibrium data of Th(IV) conformed the Langmuir isotherm in the single system, while those were best fitted by Dubinin-Radushkevich (D-R) isotherm in multi-component system. Thermodynamic parameters such as ΔH°, ΔS°, and ΔG° indicated that the nature of adsorption process was spontaneous, endothermic and thermodynamically favored. The inhibitory effect of other metal ions on the adsorption capacity of Th(IV) was in order of Al(III) > Cu(II) > Cd(II) > Ni(II) > U(VI) > Fe(II).

  1. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2012-04-01 2012-04-01 false Making alcohol or water solutions of denaturants. 19.385 Section 19.385 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO... alcohol or water solutions of denaturants. If a proprietor uses a denaturant that is difficult to...

  2. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2011-04-01 2011-04-01 false Making alcohol or water solutions of denaturants. 19.385 Section 19.385 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO... alcohol or water solutions of denaturants. If a proprietor uses a denaturant that is difficult to...

  3. Ionic conductivity studies in crystalline PVA/NaAlg polymer blend electrolyte doped with alkali salt KCl

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    Potassium Chloride (KCl) doped poly(vinyl alcohol) (PVA)/sodium alginate (NaAlg) in 60:40 wt% polymer blend electrolytes were prepared by solution casting method. The complexation of KCl with host PVA/NaAlg blend is confirmed by FTIR and UV-Vis spectra. The XRD studies show that the crystallinity of the prepared blends increases with increase in doping. The dc conductivity increases with increase in dopant concentration. Temperature dependent dc conductivity shows an Arrhenius behavior. The dielectric properties show that both the dielectric constant and dielectric loss increases with increase in KCl doping concentration and decreases with frequency. The cole-cole plots show a decrease in bulk resistance, indicates the increase in ac conductivity, due to increase in charge carrier mobility. The doping of KCl enhances the mechanical properties of PVA/NaAlg, such as Young's modulus, tensile strength, stiffness.

  4. Isothermal and non-isothermal crystallization kinetics of PVA + ionic liquid [BDMIM][BF4]-based polymeric films

    NASA Astrophysics Data System (ADS)

    Saroj, A. L.; Chaurasia, S. K.; Kataria, Shalu; Singh, R. K.

    2016-06-01

    The effect of ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate [BDMIM][BF4], on crystallization behavior of poly(vinyl alcohol) (PVA) has been studied by isothermal and non-isothermal differential scanning calorimetry techniques. The PVA + IL based polymer electrolyte films have been prepared using solution casting technique. To describe the isothermal and non-isothermal crystallization kinetics, several kinetic equations have been employed on PVA + IL based films. There is strong dependence of the peak crystallization temperature (Tc), relative degree of crystallity (Xt), half-time of crystallization (t1/2), crystallization rate constants (Avrami Kt and Tobin AT), and Avrami (n) and Tobin (nT) exponents on the cooling rate and IL loading.

  5. Zirconium/PVA modified flat-sheet PVDF membrane as a cost-effective adsorptive and filtration material: A case study on decontamination of organic arsenic in aqueous solutions.

    PubMed

    Zhao, Dandan; Yu, Yang; Wang, Chenghong; Chen, J Paul

    2016-09-01

    Organic arsenic in waters has been a global concern in drinking water due to its higher toxicity to humans. In this study, a novel zirconium/polyvinyl alcohol (PVA) modified polyvinylidene fluoride (PVDF) membrane was applied to remove organic arsenic from water. The impregnation of zirconium ions within the modified membrane was attributed to the coordination reactions among the zirconium ions, ether and hydroxyl groups. The synthesized membrane worked better at the acidic conditions and achieved the optimal uptake for both monomethylarsonic (MMA) and dimethylarsinic (DMA) at pH 2.0. The adsorption isotherm study demonstrated that the adsorption of both organic arsenic species was controlled by the mono-layer adsorption process; the maximum adsorption capacities for MMA and DMA were 73.04 and 37.53mg/g at pH 2, and 29.78 and 19.03mg/g at pH 7.0, respectively. The presence of humic acid had a negligible impact on the uptake of organic arsenic, whereas varying impacts on the arsenic adsorption were observed due to the presence of coexisting anions such as fluoride, phosphate, carbonate and silicate. A single piece of membrane with a surface area of only 12.56cm(2) could treat 7.5-L MMA and 4.1-L DMA solution with an influent concentration of about 100μg/L to meet the WHO and USEPA standard of 10μg/L. Based on the XPS analyses, the ion exchange reaction between chloride ions on the membrane surface and organic arsenic species was responsible for the removal of both MMA and DMA. PMID:27267042

  6. Studies on PVA pectin cryogels containing crosslinked enzyme aggregates of keratinase.

    PubMed

    Martínez, Yanina N; Cavello, Ivana; Cavalitto, Sebastián; Illanes, Andres; Castro, Guillermo R

    2014-05-01

    Polyvinyl alcohol-pectin (PVA-P) films containing enrofloxacin and keratinase were developed to treat wounds and scars produced by burns and skin injuries. However, in order to prevent enzyme inactivation at the interface between the patch and the scars, crosslinked enzyme aggregates (CLEAs) from a crude extract of keratinase produced by Paecilomyces lilacinus (LPSC#876) were synthesized by precipitation with acetone and crosslinking with glutaraldehyde. Soluble vs. CLEA keratinase (K-CLEA) activities were tested in 59% (v/v) hydrophobic (isobutanol and n-hexane) and hydrophilic (acetone and dimethylsulfoxide) solvents mixtures. K-CLEA activity was 1.4, 1.7 and 6.6 times higher in acetone, n-hexane and isobutanol than the soluble enzyme at 37 °C after 1 h of incubation, respectively. K-CLEA showed at least 45% of enzyme residual activity in the 40-65 °C range, meanwhile the soluble biocatalyst was fully inactivated at 65 °C after 1h incubation. Also, the soluble enzyme was completely inactivated after 12 h at pH 7.4 and 45 °C, even though K-CLEA retained full activity. The soluble keratinase was completely inactivated at 37 °C after storage in buffer solution (pH 7.4) for 2 months, meanwhile K-CLEAs kept 51% of their activity. K-CLEA loaded into polyvinyl alcohol (PVA) and PVA-P cryogels showed six times lower release rate compared to the soluble keratinase at skin pH (5.5). Small angle X-ray scattering (SAXS) analysis showed that K-CLEA bound to pectin rather than to PVA in the PVA-P matrix. PMID:24657614

  7. Silk Nanospheres and Microspheres from Silk/PVA Blend Films for Drug Delivery

    PubMed Central

    Wang, Xiaoqin; Yucel, Tuna; Lu, Qiang; Hu, Xiao; Kaplan, David L.

    2009-01-01

    Silk fibroin protein-based micro- and nanospheres provide new options for drug delivery due to their biocompatibility, biodegradability and their tunable drug loading and release properties. In the present study, we report a new aqueous-based preparation method for silk spheres with controllable sphere size and shape. The preparation was based on phase separation between silk fibroin and polyvinyl alcohol (PVA) at a weight ratio of 1/1 and 1/4. Water-insoluble silk spheres were easily obtained from the blend in a three step process: (1) air-drying the blend solution into a film, (2) film dissolution in water and (3) removal of residual PVA by subsequent centrifugation. In both cases, the spheres had approximately 30% beta-sheet content and less than 5% residual PVA. Spindle-shaped silk particles, as opposed to the spherical particles formed above, were obtained by stretching the blend films before dissolving in water. Compared to the 1/1 ratio sample, the silk spheres prepared from the 1/4 ratio sample showed a more homogeneous size distribution ranging from 300 nm up to 20 μm. Further studies showed that sphere size and polydispersity could be controlled either by changing the concentration of silk and PVA or by applying ultrasonication on the blend solution. Drug loading was achieved by mixing model drugs in the original silk solution. The distribution and loading efficiency of the drug molecules in silk spheres depended on their hydrophobicity and charge, resulting in different drug release profiles. The entire fabrication procedure could be completed within one day. The only chemical used in the preparation except water was PVA, an FDA-approved ingredient in drug formulations. Silk micro- and nanospheres reported have potential as drug delivery carriers in a variety of biomedical applications. PMID:19945157

  8. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2014-04-01 2014-04-01 false Making alcohol or water solutions of denaturants. 19.385 Section 19.385 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU, DEPARTMENT OF THE TREASURY ALCOHOL DISTILLED SPIRITS PLANTS...

  9. Electron beam crosslinked PEO and PEO/PVA hydrogels for wound dressing

    NASA Astrophysics Data System (ADS)

    Yoshii, F.; Zhanshan, Y.; Isobe, K.; Shinozaki, K.; Makuuchi, K.

    1999-06-01

    In order to prepare polyethylene oxide (PEO) hydrogel for wound dressing, different molecular weight PEO and PEO/poly(vinyl alcohol), PVA blend hydrogels were obtained with electron beam irradiation. Gel formation of PEO in aqueous solution was saturated at 40 kGy and the achieved gel fraction was 60-70%. The PEO hydrogel obtained was very fragile, hence PVA was added at 10-30% to give toughness to the PEO hydrogel. The PEO/PVA hydrogel blend showed satisfactory properties for wound dressing. To evaluate the healing effect of PEO/PVA hydrogel blend for dressing, the hydrogel covered a wound formed on the back of marmots. Healing under the wet environment of the hydrogel dressing had some advantages compared with that of gauze dressing which gives a dry environment: (1) the healing rate is faster, (2) easier to change the dressing, i.e. the hydrogel can be peeled off without any damage to the regenerated surface, and (3) no dressing material remains on the wound.

  10. Temperature-sensitive PVA/PNIPAAm semi-IPN hydrogels with enhanced responsive properties.

    PubMed

    Zhang, Jian-Tao; Bhat, Rahila; Jandt, Klaus D

    2009-01-01

    A series of temperature-sensitive hydrogels of semi-interpenetrating polymeric networks (semi-IPN) composed of poly(N-isopropylacrylamide) (PNIPAAm) and poly(vinyl alcohol) (PVA) were prepared by radical polymerization. The PNIPAAm networks were cross-linked by N,N'-methylenebisacrylamide in the presence of linear PVA. The reaction processes were investigated by rheometry using oscillatory deformation tests. It was found that gelations were very fast and the modulus reached equilibrium within about 12.5min. The prepared semi-IPN hydrogels were characterized for their morphologies and thermal behaviors by scanning electron microscopy and differential scanning calorimetry, respectively. The interior network structures of the semi-IPN matrix became more porous with increasing PVA. In comparison to the conventional PNIPAAm gel, the newly reported semi-IPN hydrogels exhibited the same lower critical solution temperature. Their swelling properties, such as temperature dependence of equilibrium swelling ratio, shrinking kinetics and reswelling kinetics in water, were also studied. Experimental data indicated that the shrinking and reswelling rates of the semi-IPN hydrogels were much faster than those of the conventional PNIPAAm hydrogels. With this novel approach, water absorption and response properties could be adjusted by tuning the feed ratio of NIPAAm and PVA. These fast responsive hydrogels exhibited improved temperature sensitivity and swelling properties compared to the conventional PNIPAAm hydrogel, which would be critical and desirable for a gel to find potential applications in biomedical fields, such as drug delivery systems and sensors. PMID:18656431

  11. Surface studies of microcrystalline chitosan/poly(vinyl alcohol) mixtures

    NASA Astrophysics Data System (ADS)

    Lewandowska, Katarzyna

    2012-12-01

    In the present study, the surface properties of microcrystalline chitosan (MCCh), poly(vinyl alcohol) (PVA) and MCCh/PVA blends (made from acetic acid solutions with the MCCh concentration ranging from 20% to 80%) have been studied by the tapping-mode atomic force microscopy (AFM), scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The changes of topography images are considered by determining the root mean square (RMS, Rq) deviation in the image data. For PVA samples, the transition between adjacent lamellae occurs through holes, islands, and bicontinuous structures. The AFM images showed also the lamellar structure of PVA in the blend. The crystalline topography of MCCh/PVA film surface suggests the presence of PVA on the top surface. The FTIR spectra of film blends, in the amide I and II region of MCCh and the hydroxyl stretching bands of PVA have been analyzed. FTIR analysis showed the existence of a weak interaction of the hydroxyl or amino groups of microcrystalline chitosan with hydroxyl groups of PVA.

  12. Aquifer washing by micellar solutions: 2. DNAPL recovery mechanisms for an optimized alcohol surfactant solvent solution

    NASA Astrophysics Data System (ADS)

    Martel, Richard; Lefebvre, René; Gélinas, Pierre J.

    1998-03-01

    A large sand column experiment is used to illustrate the principles of complex organic contaminants (DNAPL) recovery by a chemical solution containing an alcohol ( n-butanol), a surfactant (Hostapur SAS), and two solvents ( d-limonene and toluene). The washing solution is pushed by viscous polymer solutions to keep the displacement stable. The main NAPL recovery mechanisms identified are: (1) immiscible displacement by oil saturation increase (oil swelling), oil viscosity reduction, interfacial tension lowering, and relative permeability increase; (2) miscible NAPL displacement by solubilization. Most of the NAPL was recovered in a Winsor, type II system ahead of the washing solution. The 0.8 pore volume (PV) of alcohol-surfactant-solvent solution injected recovered more than 89% of the initial residual DNAPL saturation (0.195). Winsor system types were determined by visual observation of phases and confirmed by electrical resistivity measurements of phases and water content measurements in the oleic phase. Viscosity and density lowering of the oleic phase was made using solvents and alcohol transfer from the washing solution. Small sand column tests are performed to check different rinsing strategies used to minimize washing solution residual ingredients which can be trapped in sediments. An alcohol/surfactant rinsing solution without solvent, injected behind the washing solution, minimizes solvent trapping in sediments. More than five pore volumes of polymer solution and water must be injected after the rinsing solution to decrease alcohol and SAS concentrations in sediments to an acceptable level. To obtain reasonable trapped surfactant concentrations in sediments, the displacement front between the rinsing solution and the subsequent the following polymer solution has to be stable.

  13. Broadband tuning in a passively Q-switched erbium doped fiber laser (EDFL) via multiwall carbon nanotubes/polyvinyl alcohol (MWCNT/PVA) saturable absorber

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    An MWCNT/PVA-based Q-switched erbium-doped fiber laser (EDFL) that uses a tunable bandpass filter (TBPF) as the wavelength tuning and filtering mechanism to achieve a broadband tuning range is proposed and demonstrated. The tuning range of the generated Q-switched pulses covered a wide wavelength range of 50 nm, which spanned from 1519 nm to 1569 nm and corresponded to the S- and C-band regions. In addition, the lasing and Q-switching operations had low thresholds of 8.9 mW and 22.4 mW respectively. The highest pulse energy of 52.13 nJ was obtained at an output wavelength of 1569 nm, with a corresponding repetition rate of 26.53 kHz and pulse width of 6.10 μs, at the maximum power of 114.8 mW.

  14. Impedance studies of a green blend polymer electrolyte based on PVA and Aloe-vera

    NASA Astrophysics Data System (ADS)

    Selvalakshmi, S.; Mathavan, T.; Vijaya, N.; Selvasekarapandian, Premalatha, M.; Monisha, S.

    2016-05-01

    The development of polymer electrolyte materials for energy generating and energy storage devices is a challenge today. A new type of blended green electrolyte based on Poly-vinyl alcohol (PVA) and Aloe-vera has been prepared by solution casting technique. The blending of polymers may lead to the increase in stability due to one polymer portraying itself as a mechanical stiffener and the other as a gelled matrix supported by the other. The prepared blend electrolytes were subjected to Ac impedance studies. It has been found out that the polymer film in which 1 gm of PVA was dissolved in 40 ml of Aloe-vera extract exhibits highest conductivity and its value is 3.08 × 10-4 S cm-1.

  15. Microstructural and electrical properties of PVA/PVP polymer blend films doped with cupric sulphate

    NASA Astrophysics Data System (ADS)

    Hemalatha, K.; Mahadevaiah, Gowtham, G. K.; Urs, G. Thejas; Somashekarappa, H.; Somashekar, R.

    2016-05-01

    A series of polyvinyl alcohol (PVA)/polyvinyl pyrrolidone (PVP) polymer blends added with different concentrations of cupric sulphate (CuSO4) were prepared by solution casting method and were subjected to X-ray diffraction (XRD) and Ac conductance measurements. An attempt has been made to study the changes in crystal imperfection parameters in PVA/PVP blend films with the increase in concentration of CuSO4. Results show that decrease in micro crystalline parameter values is accompanied with increase in the amorphous content in the film which is the reason for film to have more flexibility, biodegradability and good ionic conductivity. AC conductance measurements in these films show that the conductivity increases as the concentration of CuSO4 increases. These films were suitable for electro chemical applications.

  16. Characterization of proton conducting blend polymer electrolyte using PVA-PAN doped with NH4SCN

    NASA Astrophysics Data System (ADS)

    Premalatha, M.; Mathavan, T.; Selvasekarapandian, S.; Genova, F. Kingslin Mary; Umamaheswari, R.

    2016-05-01

    Polymer electrolytes with proton conductivity based on blend polymer using polyvinyl alcohol (PVA) and poly acrylo nitrile (PAN) doped with ammonium thiocyanate have been prepared by solution casting method using DMF as solvent. The complex formation between the blend polymer and the salt has been confirmed by FTIR Spectroscopy. The amorphous nature of the blend polymer electrolytes have been confirmed by XRD analysis. The highest conductivity at 303 K has been found to be 3.25 × 10-3 S cm-1 for 20 mol % NH4SCN doped 92.5PVA:7.5PAN system. The increase in conductivity of the doped blend polymer electrolytes with increasing temperature suggests the Arrhenius type thermally activated process. The activation energy is found to be low (0.066 eV) for the highest conductivity sample.

  17. Cell proliferation on PVA/sodium alginate and PVA/poly(γ-glutamic acid) electrospun fiber.

    PubMed

    Yang, Jen Ming; Yang, Jhe Hao; Tsou, Shu Chun; Ding, Chian Hua; Hsu, Chih Chin; Yang, Kai Chiang; Yang, Chun Chen; Chen, Ko Shao; Chen, Szi Wen; Wang, Jong Shyan

    2016-09-01

    To overcome the obstacles of easy dissolution of PVA nanofibers without crosslinking treatment and the poor electrospinnability of the PVA cross-linked nanofibers via electrospinning process, the PVA based electrospun hydrogel nanofibers are prepared with post-crosslinking method. To expect the electrospun hydrogel fibers might be a promising scaffold for cell culture and tissue engineering applications, the evaluation of cell proliferation on the post-crosslinking electrospun fibers is conducted in this study. At beginning, poly(vinyl alcohol) (PVA), PVA/sodium alginate (PVASA) and PVA/poly(γ-glutamic acid) (PVAPGA) electrospun fibers were prepared by electrospinning method. The electrospun PVA, PVASA and PVAPGA nanofibers were treated with post-cross-linking method with glutaraldehyde (Glu) as crosslinking agent. These electrospun fibers were characterized with thermogravimetry analysis (TGA) and their morphologies were observed with a scanning electron microscope (SEM). To support the evaluation and explanation of cell growth on the fiber, the study of 3T3 mouse fibroblast cell growth on the surface of pure PVA, SA, and PGA thin films is conducted. The proliferation of 3T3 on the electrospun fiber surface of PVA, PVASA, and PVAPGA was evaluated by seeding 3T3 fibroblast cells on these crosslinked electrospun fibers. The cell viability on electrospun fibers was conducted with water-soluble tetrazolium salt-1 assay (Cell Proliferation Reagent WST-1). The morphology of the cells on the fibers was also observed with SEM. The results of WST-1 assay revealed that 3T3 cells cultured on different electrospun fibers had similar viability, and the cell viability increased with time for all electrospun fibers. From the morphology of the cells on electrospun fibers, it is found that 3T3 cells attached on all electrospun fiber after 1day seeded. Cell-cell communication was noticed on day 3 for all electrospun fibers. Extracellular matrix (ECM) productions were found and

  18. Oxidative alkoxylation of phosphine in alcohol solutions of copper halides

    NASA Astrophysics Data System (ADS)

    Polimbetova, G. S.; Borangazieva, A. K.; Ibraimova, Zh. U.; Bugubaeva, G. O.; Keynbay, S.

    2016-08-01

    The phosphine oxidation reaction with oxygen in alcohol solutions of copper (I, II) halides is studied. Kinetic parameters, intermediates, and by-products are studied by means of NMR 31Р-, IR-, UV-, and ESR- spectroscopy; and by magnetic susceptibility, redox potentiometry, gas chromatography, and elemental analysis. A reaction mechanism is proposed, and the optimum conditions are found for the reaction of oxidative alkoxylation phosphine.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Electrical properties of starch-PVA biodegradable polymer blend

    NASA Astrophysics Data System (ADS)

    Chatterjee, B.; Kulshrestha, N.; Gupta, P. N.

    2015-02-01

    Solid polymer electrolyte films were prepared by adding different contents of potassium chloride (KCl) in a polymer matrix composed of two versatile biodegradable polymers: starch and polyvinyl alcohol (PVA), using the solution cast method. The complexation of the added salt (KCl) with the polymer matrix was confirmed from an x-ray diffraction study (XRD). The evolution of a smooth and uniform morphology with the increasing content of KCl was confirmed from scanning electron microscopy (SEM). The transference number measurement established ions as the dominant charge carriers in the system. The maximum ionic conductivity ˜5.44 × 10-5 S cm-1 at ambient conditions was obtained for the film with 1.5 wt% of KCl using complex impedance spectroscopy. The ionic conductivity and dielectric constant increased with the salt content, thus affirming the amplification in the number of charge carriers. The noteworthy aspect of the investigation is the observation of appreciable ionic conductivity at a relatively low salt content. Low values of activation energy obtained from temperature-dependent ionic conductivity could be favorable from the point of view of the application. Electric modulus studies confirmed the absence of electrode polarization effects in the polymer electrolyte films. The scaling of the electric modulus shows a distribution of relaxation times in the polymer electrolyte films. The study unveils the efficiency of the starch-PVA blend, with glycerol and citric acid as additives, as a hopeful material for preparing biodegradable solid polymer electrolyte films.

  5. Poly(vinyl alcohol) Modified Porous Graphitic Carbon Stationary Phase for Hydrophilic Interaction Liquid Chromatography.

    PubMed

    Hou, Yanjie; Zhang, Feifang; Liang, Xinmiao; Yang, Bingcheng; Liu, Xiaodong; Dasgupta, Purnendu K

    2016-05-01

    We report a poly(vinyl alcohol) (PVA)-coated porous graphitic carbon (PGC, Hypercarb) packing as a novel stationary phase for hydrophilic interaction liquid chromatography (HILIC). The exterior and the pores of the PGC particles are coated with a thin layer of PVA by soaking the particles in a PVA solution, filtering, and thermally cross-linking the PVA. Such PVA coated PGC particles (5.7 μm diameter), hereinafter called PVA-PGC are stable at least through pH 1.0-12.7, can be made in <2 h, and exhibit different selectivity relative to six commercial HILIC phases and bare PGC. To our knowledge, this is the first fully pH-stable, completely neutral HILIC phase. Excellent efficiency stable is observed for polar analytes (∼70 000 and 118 000 plates/m for cytosine and resorcinol, respectively). Retention closely resembles standard HILIC behavior. Other substances can also be easily incorporated in the PVA layer; an anion exchange column can be readily made by incorporating diallyldimethylammonium chloride in the PVA coating solution. The ease of preparation without the requirement of synthetic skills or paraphernalia and the possibility of incorporating a variety of modifiers makes this a particularly versatile approach. PMID:27053418

  6. Does Disease Matter? Incorporating Solution-Focused Brief Therapy in Alcoholism Treatment.

    ERIC Educational Resources Information Center

    Osborn, Cynthia J.

    1997-01-01

    Surveyed alcoholism counselors (N=284) to determine whether the disease concept of alcoholism precludes acceptance and use of Solution-Focused Brief Therapy (SFBT) in alcoholism treatment. Results suggest that SFBT may be feasible for alcoholism treatment and that endorsement of the disease concept is compatible with the principles of SFBT. (EMK)

  7. Carbonized properties of iodine-incorporated poly(vinyl alcohol) composite films prepared by gelation/crystallization from solution.

    PubMed

    Nakano, Yumiko; Matsuo, Masaru

    2010-02-16

    Poly(vinyl alcohol) (PVA) and titanium dioxide (TiO(2)) composite films were prepared by gelation/crystallization from a dispersed solution containing different TiO(2) contents against PVA. Iodine was incorporated into the composites, and the iodine-incorporated composites were carbonized under argon gas in the temperature range of 700-1600 degrees C. Under the carbonization process, the incorporation of iodine into composites ensured tough films without cracks. This indicated that iodine incorporation played an important role as a catalyst to promote the formation of cross links between amorphous carbon chains through the resultant Ti-C structure that occurs by hydration. Surprisingly, X-ray diffraction intensity measurements revealed that the coagulated TiO(2) powders in the composite film carbonized at 1200 degrees C remained predominantly anatase type, which has generally been known as photocatalytic activity. The perfect transition to the rutile-type structure dramatically occurred at 1600 degrees C. Judging from the carbon coating on the TiO(2) particle surface as detected by ESCA, no disruption of the composite was found to be due to the appearances of Ti(2)O(3) groups and the Ti-C structure performing cross linking between neighboring amorphous carbon chains. The characteristics of anatase-type TiO(2) crystallites and amorphous carbon structures were analyzed using the para-crystalline theory concerning the distance fluctuation between graphene sheets. The electrical conductivity of the carbonized composite was ca. 0.01 S/cm and was independent of the TiO(2) admixed in the carbon matrix. PMID:19883066

  8. Retardation Measurements of Infrared PVA Wave plate

    NASA Astrophysics Data System (ADS)

    Sun, Y.; Z, H.; W, D.; D, Y.; Z, Z.; S, J.

    The wave plate made of Polyvinyl Alcohol PVA plastic film has several advantages such as its lower cost and insensitivity to temperature and incidence angle so it has been used in the Solar Multi-Channel Telescope SMCT in China But the important parameter retardations of PVA wave plates in the near infrared wavelength have never been provided In this paper a convenient and high precise instrument to get the retardations of discrete wavelengths or a continuous function of wavelength in near infrared is developed In this method the retardations of wave plates have been determined through calculating the maximum and minimum of light intensity The instrument error has been shown Additionally we can get the continuous direction of wavelength retardations in the ultraviolet visible or infrared spectral in another way

  9. Studies on PVA based nanocomposite Proton Exchange Membrane for Direct methanol fuel cell (DMFC) applications

    NASA Astrophysics Data System (ADS)

    Bahavan Palani, P.; Kannan, R.; Rajashabala, S.; Rajendran, S.; Velraj, G.

    2015-02-01

    Different concentrations of Poly (vinyl alcohol)/Montmorillonite (PVA/MMT) based proton exchange membranes (PEMs) have been prepared by solution casting method. The structural and electrical properties of these composite membranes have been characterized by using X-ray diffraction (XRD), Fourier transform infrared spectroscopic (FTIR) and AC impedance spectroscopic methods. The conductivity of the PEMs has been estimated for the different concentration of MMT. Water/Methanol uptake measurement were also analyzed for the prepared PEMs and presented. The proton conductivity studies were carried out at room temperature with 100% of humidity.

  10. Effects of PVA coated nanoparticles on human immune cells

    PubMed Central

    Strehl, Cindy; Gaber, Timo; Maurizi, Lionel; Hahne, Martin; Rauch, Roman; Hoff, Paula; Häupl, Thomas; Hofmann-Amtenbrink, Margarethe; Poole, A Robin; Hofmann, Heinrich; Buttgereit, Frank

    2015-01-01

    Nanotechnology provides new opportunities in human medicine, mainly for diagnostic and therapeutic purposes. The autoimmune disease rheumatoid arthritis (RA) is often diagnosed after irreversible joint structural damage has occurred. There is an urgent need for a very early diagnosis of RA, which can be achieved by more sensitive imaging methods. Superparamagnetic iron oxide nanoparticles (SPION) are already used in medicine and therefore represent a promising tool for early diagnosis of RA. The focus of our work was to investigate any potentially negative effects resulting from the interactions of newly developed amino-functionalized amino-polyvinyl alcohol coated (a-PVA) SPION (a-PVA-SPION), that are used for imaging, with human immune cells. We analyzed the influence of a-PVA-SPION with regard to cell survival and cell activation in human whole blood in general, and in human monocytes and macrophages representative of professional phagocytes, using flow cytometry, multiplex suspension array, and transmission electron microscopy. We found no effect of a-PVA-SPION on the viability of human immune cells, but cytokine secretion was affected. We further demonstrated that the percentage of viable macrophages increased on exposure to a-PVA-SPION. This effect was even stronger when a-PVA-SPION were added very early in the differentiation process. Additionally, transmission electron microscopy analysis revealed that both monocytes and macrophages are able to endocytose a-PVA-SPION. Our findings demonstrate an interaction between human immune cells and a-PVA-SPION which needs to be taken into account when considering the use of a-PVA-SPION in human medicine. PMID:26056442

  11. Effects of PVA coated nanoparticles on human immune cells.

    PubMed

    Strehl, Cindy; Gaber, Timo; Maurizi, Lionel; Hahne, Martin; Rauch, Roman; Hoff, Paula; Häupl, Thomas; Hofmann-Amtenbrink, Margarethe; Poole, A Robin; Hofmann, Heinrich; Buttgereit, Frank

    2015-01-01

    Nanotechnology provides new opportunities in human medicine, mainly for diagnostic and therapeutic purposes. The autoimmune disease rheumatoid arthritis (RA) is often diagnosed after irreversible joint structural damage has occurred. There is an urgent need for a very early diagnosis of RA, which can be achieved by more sensitive imaging methods. Superparamagnetic iron oxide nanoparticles (SPION) are already used in medicine and therefore represent a promising tool for early diagnosis of RA. The focus of our work was to investigate any potentially negative effects resulting from the interactions of newly developed amino-functionalized amino-polyvinyl alcohol coated (a-PVA) SPION (a-PVA-SPION), that are used for imaging, with human immune cells. We analyzed the influence of a-PVA-SPION with regard to cell survival and cell activation in human whole blood in general, and in human monocytes and macrophages representative of professional phagocytes, using flow cytometry, multiplex suspension array, and transmission electron microscopy. We found no effect of a-PVA-SPION on the viability of human immune cells, but cytokine secretion was affected. We further demonstrated that the percentage of viable macrophages increased on exposure to a-PVA-SPION. This effect was even stronger when a-PVA-SPION were added very early in the differentiation process. Additionally, transmission electron microscopy analysis revealed that both monocytes and macrophages are able to endocytose a-PVA-SPION. Our findings demonstrate an interaction between human immune cells and a-PVA-SPION which needs to be taken into account when considering the use of a-PVA-SPION in human medicine. PMID:26056442

  12. 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.

  13. 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.

  14. Aquifer washing by micellar solutions: 1. Optimization of alcohol-surfactant-solvent solutions

    NASA Astrophysics Data System (ADS)

    Martel, Richard; Gélinas, Pierre J.; Desnoyers, Jacques E.

    1998-03-01

    Phase diagrams were used for the formulation of alcohol-surfactant-solvent and to identify the DNAPL (Dense Non Aqueous Phase Liquid) extraction zones. Four potential extraction zones of Mercier DNAPL, a mixture of heavy aliphatics, aromatics and chlorinated hydrocarbons, were identified but only one microemulsion zone showed satisfactory DNAPL recovery in sand columns. More than 90 sand column experiments were performed and demonstrate that: (1) neither surfactant in water, alcohol-surfactant solutions, nor pure solvent can effectively recover Mercier DNAPL and that only alcohol-surfactant-solvent solutions are efficient; (2) adding salts to alcohol-surfactant or to alcohol-surfactant-solvent solutions does not have a beneficial effect on DNAPL recovery; (3) washing solution formulations are site specific and must be modified if the surface properties of the solids (mineralogy) change locally, or if the interfacial behavior of liquids (type of oil) changes; (4) high solvent concentrations in washing solutions increase DNAPL extraction but also increase their cost and decrease their density dramatically; (5) maximum DNAPL recovery is observed with alcohol-surfactant-solvent formulations which correspond to the maximum solubilization in Zone C of the phase diagram; (6) replacing part of surfactant SAS by the alcohol n-butanol increases washing solution efficiency and decreases the density and the cost of solutions; (7) replacing part of n-butanol by the nonionic surfactant HOES decreases DNAPL recovery and increases the cost of solutions; (8) toluene is a better solvent than D-limonene because it increases DNAPL recovery and decreases the cost of solutions; (9) optimal alcohol-surfactant-solvent solutions contain a mixture of solvents in a mass ratio of toluene to D-limonene of one or two. Injection of 1.5 pore volumes of the optimal washing solution of n-butanol-SAS-toluene- D-limonene in water can recover up to 95% of Mercier DNAPL in sand columns. In the first

  15. Apatite coating of electrospun PLGA fibers using a PVA vehicle system carrying calcium ions.

    PubMed

    Kim, In Ae; Rhee, Sang-Hoon

    2010-01-01

    A novel method to coat electrospun poly(D,L-lactic-co-glycolic acid) (PLGA) fiber surfaces evenly and efficiently with low-crystalline carbonate apatite crystals using a poly(vinyl alcohol) (PVA) vehicle system carrying calcium ions was presented. A non-woven PLGA fabric was prepared by electrospinning: a 10 wt% PLGA solution was prepared using 1,1,3,3-hexafluoro-2-propanol as a solvent and electrospun under a electrical field of 1 kV/cm using a syringe pump with a flowing rate of 3 ml/h. The non-woven PLGA fabric, 12 mm in diameter and 1 mm in thickness, was cut and then coated with a PVA solution containing calcium chloride dihydrate (specimen PPC). As controls, pure non-woven PLGA fabric (specimen P) and fabric coated with a calcium chloride dihydrate solution without PVA (specimen PC) were also prepared. Three specimens were exposed to simulated body fluid for 1 week and this exposure led to form uniform and complete apatite coating layer on the fiber surfaces of specimen PPC. However, no apatite had formed to the fiber surfaces of specimen P and only inhomogeneous coating occurred on the fiber surfaces of specimen PC. These results were explained in terms of the calcium chelating and adhesive properties of PVA vehicle system. The practical implication of the results is that this method provides a simple but efficient technique for coating the fiber surface of an initially non-bioactive material with low-crystalline carbonate apatite. PMID:20507712

  16. 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. PMID:22925275

  17. Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

    NASA Astrophysics Data System (ADS)

    Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeda, T.

    2005-01-01

    We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40 , and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does include only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed.

  18. Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

    SciTech Connect

    Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeda, T.

    2005-01-01

    We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does include only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed.

  19. Synthesis and characterization of alkaline polyvinyl alcohol and poly(epichlorohydrin) blend polymer electrolytes and performance in electrochemical cells

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Lin, Sheng-Jen; Hsu, Sung-Ting

    Alkaline SPE was obtained from a blend of polyvinyl alcohol (PVA) and poly(epichlorohydrin) (PECH), PVA-PECH, by a solution-cast technique. The PVA host polymer is blended with PECH polymer to provide a polymer electrolyte with improved chemical and mechanical properties. The ionic conductivity of the PVA-PECH polymer electrolytes is between 10 -2 and 10 -3 S cm -1 at room temperature when the blend ratio is varied from 1:0.2 to 1:1. The PVA-PECH polymer was characterized by means of scanning electron microscopy, X-ray diffraction, stress-strain test, cyclic voltammetry, and a.c. impedance spectroscopy. It is found that the polymer electrolytes exhibit good mechanical strength and excellent chemical stability. The electrochemical performance of solid-state Zn-air batteries with various types of the blended polymer electrolyte films is examined by a galvanostatic discharge method.

  20. Radiation preparation of graphene/carbon nanotubes hybrid fillers for mechanical reinforcement of poly(vinyl alcohol) films

    NASA Astrophysics Data System (ADS)

    Ma, Hui-Ling; Zhang, Long; Zhang, Youwei; Wang, Shuojue; Sun, Chao; Yu, Hongyan; Zeng, Xinmiao; Zhai, Maolin

    2016-01-01

    Graphene/carbon nanotubes (G/CNTs) hybrid fillers were synthesized by γ-ray radiation reduction of graphene oxide (GO) in presence of CNTs. The obtained hybrid fillers with three-dimensional (3D) interconnected network structure were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). Poly(vinyl alcohol) (PVA) composite films with enhanced mechanical properties and thermal stability were subsequently prepared by solution blending of G/CNTs with PVA matrix. The tensile strength and Young's modulus of PVA composite films containing 1 wt% G/CNTs were measured to be 81.9 MPa and 3.9 GPa respectively, which were 56% and 33.6% higher than those of pure PVA. These substantial improvements could be attributed to the interconnected 3D structure of G/CNTs, homogeneous dispersion as well as the strong hydrogen-bonding interaction between G/CNTs and PVA macromolecular chains.

  1. Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions

    NASA Technical Reports Server (NTRS)

    Leu, Ming-Taun

    2006-01-01

    We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

  2. Holographic characterization of DYE-PVA films studied at 442 nm for optical elements fabrication

    NASA Astrophysics Data System (ADS)

    Couture, Jean J.

    1991-12-01

    The present work is an experimental study of the speed of hologram recording in dichromated polyvinyl alcohol films (DC-PVA) and DYE-DC-PVA films. Real-time recordings give high diffraction efficiency and low signal-to-noise ratio holograms without any chemical development. The dyes studied here are MALACHITE GREEN, EOSIN Y, and ROSE BENGAL introduced in DC-PVA films having a thickness of 60 - 62 micrometers . The best of these DYE-DC-PVA systems is a good candidate for holographic optical elements fabrication.

  3. Comparison of properties of poly(vinyl alcohol) nanocomposites containing two different clays.

    PubMed

    Chang, Jin-Hae; Ham, Miran; Kim, Jeong-Cheol

    2014-11-01

    Morphologies, thermo-optical properties, and gas barriers of poly(vinyl alcohol) (PVA) hybrid films containing two different clays are compared. Saponite (SPT) and hydrophilic bentonite (BTT) were used as the reinforcing filler in the fabrication of PVA hybrid films, which were synthesized from aqueous solutions and were solvent-cast at room temperature under vacuum, yielding 20-31-μm-thick PVA hybrid films with varying clay contents. The addition of small amounts of clay is sufficient to improve the thermal properties and gas barriers of PVA hybrid films. Even polymers with a low clay content (3-10 wt%) were found to exhibit much higher transition temperature values than pure PVA. The addition of BTT was more effective than the addition of SPT for improving the thermal properties and gas barrier in the PVA matrix. The PVA hybrid films containing 5 wt% SPT were equibiaxially stretched, with stretching ratios ranging from 150% to 250%. Clay dispersion, morphology, optical transparency, and gas permeability were then examined as a function of the equibiaxial stretching ratio. PVA hybrid films with a stretching ratio of ≥ 150% displayed homogeneously dispersed clay within the polymer matrix and exfoliated nanocomposites. PMID:25958603

  4. Immobilization of Firefly Luciferase on PVA-co-PE Nanofibers Membrane as Biosensor for Bioluminescent Detection of ATP.

    PubMed

    Wang, Wenwen; Zhao, Qinghua; Luo, Mengying; Li, Mufang; Wang, Dong; Wang, Yuedan; Liu, Qiongzhen

    2015-09-16

    The bioluminescent reaction catalyzed by firefly luciferase has become widely established as an outstanding analytical system for assay of adenosine triphosphate (ATP). When in solution, the luciferase is unstable and cannot be reused. The problem can be partially solved by immobilizing the luciferase on solid substrates. The poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers membrane has abundant active hydroxyl groups on the surface. The PVA-co-PE nanofibers membrane was first activated by cyanuric chloride with triazinyl group. Then the activated PVA-co-PE nanofibers membrane was subsequently reacted with 1,3-propanediamine and biotin. The firefly luciferase was immobilized onto the surface of 1,3-propanediamine- and biotin-functionalized membranes. The surface chemical structure and morphologies of nanofibers membranes were characterized by FTIR-ATR spectra and SEM. The hydrophilicity of membranes was tested by water contact angle measurements. The detection of fluorescence intensity displayed that the firefly-luciferase-immobilized PVA-co-PE nanofibers membranes indicated high catalytic activity and efficiency. Especially, the firefly-luciferase-immobilized nanofiber membrane which was functionalized by biotin can be a promising candidate as biosensor for bioluminescent detection of ATP because of its high detection sensitivity. PMID:26275118

  5. Preparation of antibacterial PVA and PEO nanofibers containing Lawsonia Inermis (henna) leaf extracts.

    PubMed

    Avci, H; Monticello, R; Kotek, R

    2013-01-01

    Concerns about health issues and environmental pollution stimulate research to find new health and hygiene related products with healing properties and minimum negative effect on the environment. Development of new, natural antibacterial agents has become one of the most important research areas to combat some pathogens such as Gram- positive and Gram-negative bacteria, fungi, algae, yeast, and some microorganisms which cause serious human infections. Lawsonia Inermis (henna) leaf extracts for preparation of antibacterial poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA) nanofibers via electrospinning technique were investigated. PEO and PVA based electrospun fibers containing henna extract were verified by the appearance of FTIR peaks corresponding to the pure extract. Our study demonstrates that 2.793 wt.% Li in PVA and PEO based solutions showed bactericidal effects against Staphylococcus aureus and bacteriostatic action to Escherichia coli. Concentrations of henna leaf extract strongly impacted antibacterial activities against both bacteria. Henna leaves have a great potential to be used as a source of a potent eco-friendly antimicrobial agent. PMID:23758488

  6. Effect of UV irradiation on optical, mechanical and microstructural properties of PVA/NaAlg blends

    NASA Astrophysics Data System (ADS)

    Sheela, T.; Bhajantri, R. F.; Ravindrachary, V.; Rathod, Sunil G.; Pujari, P. K.; Poojary, Boja; Somashekar, R.

    2014-10-01

    Poly(vinyl alcohol) (PVA)/Sodium alginate (NaAlg) blend films with 60:40 wt% were prepared by solution casting method and subjected to UV irradiation for different intervals of time. The optical, mechanical and morphological properties of the blend films were modified after UV irradiation. The FTIR and FT-Raman results show the chemical interaction between PVA and NaAlg. The UV-vis absorption peak at 278 nm shifts slightly towards longer wavelength and the absorption increases with irradiation time, indicate the increase in crosslinking network. The XRD results show an increase in amorphous nature with increase in UV irradiation time. The DSC/TGA results show a single glass transition temperature (Tg), which confirm that the blends are completely miscible and thermally stable up to 250 °C. The Young's modulus, tensile strength and stiffness of the blend films increase with increase in UV irradiation time. The SEM images confirm that the surface of 48 h UV irradiated PVA:NaAlg blend is more photo-resistant than unirradiated blend.

  7. A novel gellan-PVA nanofibrous scaffold for skin tissue regeneration: Fabrication and characterization.

    PubMed

    Vashisth, Priya; Nikhil, Kumar; Roy, Partha; Pruthi, Parul A; Singh, Rajesh P; Pruthi, Vikas

    2016-01-20

    In this investigation, we have introduced novel electrospun gellan based nanofibers as a hydrophilic scaffolding material for skin tissue regeneration. These nanofibers were fabricated using a blend mixture of gellan with polyvinyl alcohol (PVA). PVA reduced the repulsive force of resulting solution and lead to formation of uniform fibers with improved nanostructure. Field emission scanning electron microscopy (FESEM) confirmed the average diameter of nanofibers down to 50 nm. The infrared spectra (IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis evaluated the crosslinking, thermal stability and highly crystalline nature of gellan-PVA nanofibers, respectively. Furthermore, the cell culture studies using human dermal fibroblast (3T3L1) cells established that these gellan based nanofibrous scaffold could induce improved cell adhesion and enhanced cell growth than conventionally proposed gellan based hydrogels and dry films. Importantly, the nanofibrous scaffold are biodegradable and could be potentially used as a temporary substrate/or biomedical graft to induce skin tissue regeneration. PMID:26572421

  8. Processing and characterization of chitosan/PVA and methylcellulose porous scaffolds for tissue engineering.

    PubMed

    Kanimozhi, K; Khaleel Basha, S; Sugantha Kumari, V

    2016-04-01

    Biomimetic porous scaffold chitosan/poly(vinyl alcohol) CS/PVA containing various amounts of methylcellulose (MC) (25%, 50% and 75%) incorporated in CS/PVA blend was successfully produced by a freeze drying method in the present study. The composite porous scaffold membranes were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), swelling degree, porosity, degradation of films in Hank's solution and the mechanical properties. Besides these characterizations, the antibacterial activity of the prepared scaffolds was tested, toward the bacterial species Staphylococcus aureus (S.aureus) and Escherichia coli (E.coli). FTIR, XRD and DSC demonstrated that there was strong intermolecular hydrogen bonding between the molecules of CS/PVA and MC. The crystalline microstructure of the scaffold membranes was not well developed. SEM images showed that the morphology and diameter of the scaffolds were mainly affected by the weight ratio of MC. By increasing the MC content in the hybrid scaffolds, their swelling capacity and porosity increased. The mechanical properties of these scaffolds in dry and swollen state were greatly improved with high swelling ratio. The elasticity of films was also significantly improved by the incorporation of MC, and the scaffolds could also bear a relative high tensile strength. These findings suggested that the developed scaffold possess the prerequisites and can be used as a scaffold for tissue engineering. PMID:26838875

  9. Spectral studies of Donepezil release from streched PVA polymer films

    NASA Astrophysics Data System (ADS)

    Nechifor, Cristina-Delia; Zelinschi, Carmen-Beatrice; Stoica, Iuliana; Closca, Valentina; Dorohoi, Dana-Ortansa

    2013-07-01

    The focus of this research is to obtain poly vinyl alcohol (PVA) polymer foils containing Donepezil in different concentration, in order to be used in controlled drug release as a palliative treatment of mild to moderate Alzheimer's disease. The influence of polymeric foil stretching degree on drug release was analyzed using spectral measurements.

  10. Functionalized graphene oxide quantum dot-PVA hydrogel: a colorimetric sensor for Fe2+, Co2+ and Cu2+ ions

    NASA Astrophysics Data System (ADS)

    Baruah, Upama; Chowdhury, Devasish

    2016-04-01

    Functionalized graphene oxide quantum dots (GOQDs)-poly(vinyl alcohol) (PVA) hybrid hydrogels were prepared using a simple, facile and cost-effective strategy. GOQDs bearing different surface functional groups were introduced as the cross-linking agent into the PVA matrix thereby resulting in gelation. The four different types of hybrid hydrogels were prepared using graphene oxide, reduced graphene oxide, ester functionalized graphene oxide and amine functionalized GOQDs as cross-linking agents. It was observed that the hybrid hydrogel prepared with amine functionalized GOQDs was the most stable. The potential applicability of using this solid sensing platform has been subsequently explored in an easy, simple, effective and sensitive method for optical detection of M2+ (Fe2+, Co2+ and Cu2+) in aqueous media involving colorimetric detection. Amine functionalized GOQDs-PVA hybrid hydrogel when put into the corresponding solution of Fe2+, Co2+ and Cu2+ renders brown, orange and blue coloration respectively of the solution detecting the presence of Fe2+, Co2+ and Cu2+ ions in the solution. The minimum detection limit observed was 1 × 10-7 M using UV-visible spectroscopy. Further, the applicability of the sensing material was also tested for a mixture of co-existing ions in solution to demonstrate the practical applicability of the system. Insight into the probable mechanistic pathway involved in the detection process is also being discussed.

  11. 27 CFR 19.385 - Making alcohol or water solutions of denaturants.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2013-04-01 2013-04-01 false Making alcohol or water... alcohol or water solutions of denaturants. If a proprietor uses a denaturant that is difficult to dissolve... water prior to its use in the production of denatured spirits. However, the proof of the...

  12. Evolution of electrical discharge channel in isopropyl alcohol solution

    NASA Astrophysics Data System (ADS)

    Panov, V. A.; Vasilyak, L. M.; Pecherkin, V. Ya; Vetchinin, S. P.; Kulikov, Yu M.; Son, E. E.

    2015-11-01

    Evolution of the spark channel created by the high voltage pulse generator in 15% isopropyl alcohol solution in tap water was investigated experimentally. Fast camera images show the start of spark discharge channel with the anode region glowing, which is due to ionization-overheating instability near the surface of anode electrode. Measured propagation velocity is about 4 m/s and points to thermal process of channel evolution. Partial discharges in gas bubbles near the spark channel were observed. When the channel bridges the gap the cathode flash of lightning occurs which is much brighter than anode glowing and channel one. After destruction of the spark channel the cathode glowing stays for a longer period than anode one.

  13. Bioinspired design and macroscopic assembly of poly(vinyl alcohol)-coated graphene into kilometers-long fibers

    NASA Astrophysics Data System (ADS)

    Kou, Liang; Gao, Chao

    2013-05-01

    Nacre is characterized by its excellent mechanical performance due to the well-recognized ``brick and mortar'' structure. Many efforts have been applied to make nacre-mimicking materials, but it is still a big challenge to realize their continuous production. Here, we prepared sandwich-like building blocks of poly(vinyl alcohol) (PVA)-coated graphene, and achieved high-nanofiller-content kilometers-long fibers by continuous wet-spinning assembly technology. The fibers have a strict ``brick and mortar'' layered structure, with graphene sheet as rigid brick and PVA as soft mortar. The mortar thickness can be precisely tuned from 2.01 to 3.31 nm by the weight feed ratio of PVA to graphene, as demonstrated by both atomic force microscopy and X-ray diffraction measurements. The mechanical strength of the nacre-mimicking fibers increases with increasing the content of PVA, and it rises gradually from 81 MPa for the fiber with 53.1 wt% PVA to 161 MPa for the fiber with 65.8 wt% PVA. The mechanical performance of our fibers was independent of the molecular weight (MW) of PVA in the wide range of 2-100 kDa, indicating that low MW polymers can also be used to make strong nanocomposites. The tensile stress of fibers immersed in PVA 5 wt% solution reached ca. 200 MPa, surpassing the values of nacre and most of other nacre-mimicking materials. The nacre-mimicking fibers are highly electrically conductive (~350 S m-1) after immersing in hydroiodic acid, enabling them to connect a circuit to illuminate an LED lamp.Nacre is characterized by its excellent mechanical performance due to the well-recognized ``brick and mortar'' structure. Many efforts have been applied to make nacre-mimicking materials, but it is still a big challenge to realize their continuous production. Here, we prepared sandwich-like building blocks of poly(vinyl alcohol) (PVA)-coated graphene, and achieved high-nanofiller-content kilometers-long fibers by continuous wet-spinning assembly technology. The fibers

  14. Chemorheology of aqueous-based alumina-poly(vinyl alcohol) gelcasting suspensions

    SciTech Connect

    Morissette, S.L.; Lewis, J.A.

    1999-03-01

    A new gelcasting system based on aqueous-based alumina-poly(vinyl alcohol) (PVA) suspensions cross-linked by an organotitanate coupling agent has been developed. The chemorheological properties of this system exhibited a strong compositional dependence. A sol-gel phase diagram was established, which yielded the critical titanium concentration ([Ti]{sub c}) required for gelation at a given PVA volume fraction as well as the minimum PVA volume fraction ({Phi}{sub PVA}{sup min} = 0.0245) and titanium concentration ([Ti]{sub min} = 9.984 {times} 10{sup {minus}4} g of Ti/mL) below which gelation was not observed irrespective of solution composition. The gelation time of suspensions of constant PVA volume fraction ({Phi}{sub PVA}{sup soln}) decreased with increased cross-linking agent concentration, temperature, and solids volume fraction. The steady-state viscosity and elastic modulus of polymer solutions ({Phi}{sub PVA}{sup soln} = 0.05) of varying [Ti] were well described by the percolation model, giving scaling exponents of 0.84 and 1.79, respectively. The steady-state elastic modulus of gel-casting suspensions, which provided a measure of their handling strength in the as-gelled state, increased with increased solids volume fraction.

  15. Effect of pullulan/poly(vinyl alcohol) blend system on the montmorillonite structure with property characterization of electrospun pullulan/poly(vinyl alcohol)/montmorillonite nanofibers.

    PubMed

    Islam, Md Shahidul; Yeum, Jeong Hyun; Das, Ajoy Kumar

    2012-02-15

    Nanofibers of the composite of pullulan (PULL), poly(vinyl alcohol) (PVA), and montmorillonite clay (MMT) were prepared using electrospinning method in aqueous solutions. Pullulan is an interesting natural polymer for many of its merits and good properties. Because of biocompatibility and non-toxicity of PVA, it could be used in numerous fields. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were done to characterize the PULL/PVA/MMT nanofibers morphology and properties. XRD patterns and FTIR data demonstrated that there were good interactions between PULL and PVA caused by possibly hydrogen bonds. Moreover, XRD data and TEM images indicated that intercalated and exfoliated MMT nanoplatelets can be obtained within the PULL/PVA/MMT nanofibers depending on the PULL/PVA blend ratios. Furthermore, the thermal stability and mechanical property (tensile strength) of PULL/PVA/MMT nanofibers could be enhanced more by exfoliated MMT nanoplatelets than intercalated structures of that nanoplatelets. PMID:22172694

  16. Covalently-layers of PVA and PAA and in situ formed Ag nanoparticles as versatile antimicrobial surfaces.

    PubMed

    Fragal, Vanessa H; Cellet, Thelma S P; Pereira, Guilherme M; Fragal, Elizângela H; Costa, Marco Antonio; Nakamura, Celso Vataru; Asefa, Tewodros; Rubira, Adley F; Silva, Rafael

    2016-10-01

    The in situ synthesis of silver nanoparticles (AgNPs) within covalently-modified poly(ethylene terephthalate) (PET) films possessing ultra-thin layer of poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) is successfully demonstrated. The resulting polymeric films are shown to exhibit antimicrobial activities toward Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria and fungus (Candida albicans). To make the films, first PET surfaces were subject to photo-oxidation and subsequent solid-state grafting to attach a PVA layer, followed by a PAA layer. To synthesize the AgNPs inside the films, the PVA and PAA-modified PET was soaked in AgNO3 solution and the polymeric film was modified with the Ag(+) ions via Ag(+)-carboxylate interaction, and then the Ag(+) ions-containing polymer film was subject to either photo-reduction or thermal reduction processes. The PVA and PAA thin layers attached by covalent bonds to the PET surface uniquely promoted not only the in situ synthesis but also the stabilization of AgNPs. The formation of the AgNPs was confirmed by UV-vis spectroscopy or by monitoring the surface plasmon resonance (SPR) peak associated with AgNPs. The resulting PVA and PAA ultrathin layers modified and AgNPs containing PET served as bactericide and fungicide, inhibiting the growth of bacteria and fungi on the surfaces. Given PET's versatility and common use in many commercial processes, the method can be used for producing plastic surfaces with versatile antimicrobial and antibacterial properties. PMID:27196366

  17. Novel electroactive PVA-TOCN actuator that is extremely sensitive to low electrical inputs

    NASA Astrophysics Data System (ADS)

    Wang, Fan; Kim, Si-Seup; Kee, Chang-Doo; Shen, Yun-De; Oh, Il-Kwon

    2014-07-01

    A novel electroactive biopolymer actuator was developed based on a cross-linked ionic networking membrane of TEMPO-oxidized bacterial cellulose nanofibers (TOCNs) and polyvinyl alcohol (PVA). Ionic liquids were added to develop an air-working artificial muscle and to enhance the performance of the PVA-TOCN actuator. Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) conducting layers were deposited on the top and bottom surfaces of the PVA-TOCN membrane via a simple dipping and drying method. The electroactive PVA-TOCN actuator under both step and harmonic electrical inputs shows much larger tip displacements and faster bending deformation than the pure TOCN actuator. The cross-linking reaction between PVA and TOCN was observed in the Fourier transform-near-infrared (FT-IR) spectrum of the PVA-TOCN networking membrane. Scanning electron microscopy (SEM), x-ray diffusion (XRD), thermogravimetric analysis (TGA) and tensile and ion conductivity testing results for the PVA-TOCN membrane were compared with those of pristine TOCN. Most important, the PVA-TOCN actuator shows much larger bending deformation under even extremely low input voltages, and this could be attributed to the cross-linking mechanism and the greater flexibility resulting from the synergistic effects between PVA and TOCN.

  18. Effects of MWNT nanofillers on structures and properties of PVA electrospun nanofibres

    NASA Astrophysics Data System (ADS)

    Naebe, Minoo; Lin, Tong; Tian, Wendy; Dai, Liming; Wang, Xungai

    2007-06-01

    In this study, we have electrospun poly(vinyl alcohol)(PVA) nanofibres and PVA composite nanofibres containing multi-wall carbon nanotubes (MWNTs) (4.5 wt%), and examined the effect of the carbon nanotubes and the PVA morphology change induced by post-spinning treatments on the tensile properties, surface hydrophilicity and thermal stability of the nanofibres. Through differential scanning calorimetry (DSC) and wide-angle x-ray diffraction (WAXD) characterizations, we have observed that the presence of the carbon nanotubes nucleated crystallization of PVA in the MWNTs/PVA composite nanofibres, and hence considerably improved the fibre tensile strength. Also, the presence of carbon nanotubes in PVA reduced the fibre diameter and the surface hydrophilicity of the nanofibre mat. The MWNTs/PVA composite nanofibres and the neat PVA nanofibres responded differently to post-spinning treatments, such as soaking in methanol and crosslinking with glutaric dialdehyde, with the purpose of increasing PVA crystallinity and establishing a crosslinked PVA network, respectively. The presence of carbon nanotubes reduced the PVA crystallization rate during the methanol treatment, but prevented the decrease of crystallinity induced by the crosslinking reaction. In comparison with the crosslinking reaction, the methanol treatment resulted in better improvement in the fibre tensile strength and less reduction in the tensile strain. In addition, the presence of carbon nanotubes reduced the onset decomposition temperature of the composite nanofibres, but stabilized the thermal degradation for the post-spinning treated nanofibres. The MWNTs/PVA composite nanofibres treated by both methanol and crosslinking reaction gave the largest improvement in the fibre tensile strength, water contact angle and thermal stability.

  19. 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…

  20. Electromechanical properties of nanotube PVA composite actuator bimorphs

    NASA Astrophysics Data System (ADS)

    Bartholome, Christèle; Derré, Alain; Roubeau, Olivier; Zakri, Cécile; Poulin, Philippe

    2008-08-01

    Oxidized multiwalled carbon nanotube (oxidized-MWNT)/polyvinyl alcohol (PVA) composite sheets have been prepared for electromechanical actuator applications. MWNT have been oxidized by nitric acid treatments. They were then dispersed in water and mixed with various amounts of PVA of high molecular weight (198 000 g mol-1). The composite sheets were then obtained through a membrane filtration process. The composition of the systems has been optimized to combine suitable mechanical and electrical properties. Thermogravimetric analysis, mechanical tensile tests and conductivity measurements show that the best compromise of mechanical and electrical properties was obtained for a PVA weight fraction of about 30 wt%. In addition, one face of the sheets was coated with gold to increase the conductivity of the sheets and promote uniform actuation. Pseudo-bimorph devices have been realized by subsequently coating the composite sheets with an inert layer of PVA. The devices have been tested electromechanically in a liquid electrolyte (tetrabutylammonium/tetrafluoroborate (TBA/TFB) in acetonitrile) at constant frequency and different applied voltages, from 2 to 10 V. Measurements of the bimorph deflections were used to determine the stress generated by the nanotube-PVA sheets. The results show that the stress generated increases with increasing amplitude of the applied voltage and can reach 1.8 MPa. This value compares well with and even exceeds the stress generated by recently obtained bimorphs made of gold nanoparticles.

  1. 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.

  2. Electrospun Polyvinyl Alcohol/ Pluronic F127 Blended Nanofibers Containing Titanium Dioxide for Antibacterial Wound Dressing.

    PubMed

    El-Aassar, M R; El Fawal, G F; El-Deeb, Nehal M; Hassan, H Shokry; Mo, Xiumei

    2016-04-01

    In this study, an antibacterial electrospun nanofibers for wound dressing application was successfully prepared from polyvinyl alcohol (PVA), Pluronic F127 (Plur), polyethyleneimine (PEI) blend solution with titanium dioxide nanoparticles (TiO2 NPs). PVA-Plur-PEI nanofibers containing various ratios of TiO2 NPs were obtained. The formation and presence of TiO2 in the PVA-Plu-PEI/ TiO2 composite was confirmed by X-ray diffraction (XRD). Transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), mechanical measurement, and antibacterial activity were undertaken in order to characterize the PVA-Plur-PEI/TiO2 nanofiber morphology and properties. The PVA-Plu-PEI nanofibers had a mean diameter of 220 nm, and PVA-Plur-PEI/TiO2 nanofibers had 255 nm. Moreover, the antimicrobial properties of the composite were studied by zone inhibition against Gram-negative bacteria, and the result indicates high antibacterial activity. Results of this antibacterial testing suggest that PVA-Plur-PEI/TiO2 nanofiber may be effective in topical antibacterial treatment in wound care; thus, they are very promising in the application of wound dressings. PMID:26686499

  3. Synthesis of size-selected Pt nanoparticles supported on sulfonated graphene with polyvinyl alcohol for methanol oxidation in alkaline solutions

    NASA Astrophysics Data System (ADS)

    Yang, Jen-Ming; Wang, Sheng-An; Sun, Chia-Liang; Ger, Ming-Der

    2014-05-01

    In this study, the size-selected platinum (Pt) nanoparticles are loaded on sulfonated graphene with polyvinyl alcohol (PVA) as the conductive polymer for fuel-cell applications. Methanol oxidation reactions and reliability of various catalysts based on carbon black, graphene, and sulfonated graphene catalyst supports are compared under alkaline conditions. When PVA is used as the conductive polymer in place of Nafion, both the electrochemical active surface area (ECSA) and the methanol oxidation property were superior, irrespective of the catalyst and support. On the other hand, the catalyst with Pt on sulfonated graphene (Pt/sG) outperforms those on other supports. For methanol oxidation, the catalyst decay occurs with a decay of only 9.06% for Pt/sG. It is suggested that the sulfonate functional group on graphene not only improves catalytic activity but can also enhance catalyst reliability.

  4. Olfactory Impact of Higher Alcohols on Red Wine Fruity Ester Aroma Expression in Model Solution.

    PubMed

    Cameleyre, Margaux; Lytra, Georgia; Tempere, Sophie; Barbe, Jean-Christophe

    2015-11-11

    This study focused on the impact of five higher alcohols on the perception of fruity aroma in red wines. Various aromatic reconstitutions were prepared, consisting of 13 ethyl esters and acetates and 5 higher alcohols, all at the average concentrations found in red wine. These aromatic reconstitutions were prepared in several matrices. Sensory analysis revealed the interesting behavior of certain compounds among the five higher alcohols following their individual addition or omission. The "olfactory threshold" of the fruity pool was evaluated in several matrices: dilute alcohol solution, dilute alcohol solution containing 3-methylbutan-1-ol or butan-1-ol individually, and dilute alcohol solution containing the mixture of five higher alcohols, blended together at various concentrations. The presence of 3-methylbutan-1-ol or butan-1-ol alone led to a significant decrease in the "olfactory threshold" of the fruity reconstitution, whereas the mixture of alcohols raised the olfactory threshold. Sensory profiles highlighted changes in the perception of fruity nuances in the presence of the mixture of higher alcohols, with specific perceptive interactions, including a relevant masking effect on fresh- and jammy-fruit notes of the fruity mixture in both dilute alcohol solution and dearomatized red wine matrices. When either 3-methylbutan-1-ol or butan-1-ol was added to the fruity reconstitution in dilute alcohol solution, an enhancement of butyric notes was reported with 3-methylbutan-1-ol and fresh- and jammy-fruit with butan-1-ol. This study, the first to focus on the impact of higher alcohols on fruity aromatic expression, revealed that these compounds participate, both quantitatively and qualitatively, in masking fruity aroma perception in a model fruity wine mixture. PMID:26529563

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

    PubMed

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

    2013-11-01

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

  6. Thermodynamics of hydrogen bonding of weak bases in alcohol solutions: Calorimetry of solution, IR-spectroscopy and vapor pressure analysis

    NASA Astrophysics Data System (ADS)

    Zaitseva, Ksenia V.; Varfolomeev, Mikhail A.; Solomonov, Boris N.

    2012-06-01

    The properties of solutes and their reactivity in aliphatic alcohols significantly depend on the formation of hydrogen bonds. In this work, calorimetric, FTIR-spectroscopic and gas chromatographic vapor pressure studies of hydrogen bonds of weak bases in solution of aliphatic alcohols were carried out. Enthalpies of solutions at infinite dilution of ketones, nitriles and acetates in methanol and octan-1-ol were measured. Obtained from the calorimetric data, the enthalpies of specific interaction of weak bases in aliphatic alcohols unexpectedly found to be positive. IR spectra of solutions of ketones in aliphatic alcohols at infinite dilution were measured at different temperatures. Enthalpies of specific interaction in studied systems obtained from the spectroscopic data confirmed the endothermic process and are in good agreement with calorimetric results. Gibbs energies and entropies of specific interaction of weak bases in aliphatic alcohols were determined. Obtained results show, that the hydrogen bonding process of weak bases in aliphatic alcohols differs substantially from the formation of complexes 1:1 ROH⋯B (B - weak proton acceptor) in aprotic media. The complicated process of hydrogen bonding of weak bases in aliphatic alcohols apparently is controlled by the entropy factor, because these values are above zero.

  7. Lipase entrapment in PVA/Chitosan biodegradable film for reactor coatings.

    PubMed

    Batista, Karla A; Lopes, Flavio Marques; Yamashita, Fabio; Fernandes, Kátia Flávia

    2013-04-01

    This study reports the development and characterization of novel biodegradable film, based on chitosan and polyvinyl alcohol containing lipase entrapped. The films showed a thickness of 70.4 and 79 μm to PVA/Chitosan and PVA/Chitosan/Lipase, respectively. The entrapment of lipase in PVA/Chitosan film resulted in increasing of 69.4% tensile strength (TS), and 52.4% of elongation. SEM images showed the formation of a continuous film, without pores or cracks. The lipase entrapment efficiency was estimated in 92% and the films were repeatedly used for 25 hydrolytic cycles, maintaining 62% of initial activity. The PVA/Chitosan/Lipase film was used for olive oil hydrolysis of high performance. These results indicate that PVA/Chitosan/Lipase is a promising material for biotechnology applications such as triacylglycerol hydrolysis and biodiesel production. PMID:23827626

  8. Cross-linked poly (vinyl alcohol)/sulfosuccinic acid polymer as an electrolyte/electrode material for H2-O2 proton exchange membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Ebenezer, D.; Deshpande, Abhijit P.; Haridoss, Prathap

    2016-02-01

    Proton exchange membrane fuel cell (PEMFC) performance with a cross-linked poly (vinyl alcohol)/sulfosuccinic acid (PVA/SSA) polymer is compared with Nafion® N-115 polymer. In this study, PVA/SSA (≈5 wt. % SSA) polymer membranes are synthesized by a solution casting technique. These cross-linked PVA/SSA polymers and Nafion are used as electrolytes and ionomers in catalyst layers, to fabricate different membrane electrode assemblies (MEAs) for PEMFCs. Properties of each MEA are evaluated using scanning electron microscopy, contact angle measurements, impedance spectroscopy and hydrogen pumping technique. I-V characteristics of each cell are evaluated in a H2-O2 fuel cell testing fixture under different operating conditions. PVA/SSA ionomer causes only an additional ≈4% loss in the anode performance compared to Nafion ionomer. The maximum power density obtained from PVA/SSA based cells range from 99 to 117.4 mW cm-2 with current density range of 247 to 293.4 mA cm-2. Ionic conductivity of PVA/SSA based cells is more sensitive to state of hydration of MEA, while maximum power density obtained is less sensitive to state of hydration of MEA. Maximum power density of cross-linked PVA/SSA membrane based cell is about 35% that of Nafion® N-115 based cell. From these results, cross-linked PVA/SSA polymer is identified as potential candidate for PEMFCs.

  9. Effects of PVA organic binder on electric properties of CaCu3Ti4O12 ceramics

    NASA Astrophysics Data System (ADS)

    Yuan, Wen-Xiang; Li, Z. J.

    2012-04-01

    CaCu3Ti4O12 ceramics with incorporation of polyvinyl alcohol (PVA) are prepared from the powder synthesized by a solid state reaction. Their electric and dielectric properties are investigated in this study. It is found that adding PVA can dramatically reduce the dielectric loss of CCTO in the low frequency region, and stabilize the dependence of dielectric constant on the measuring frequency. The minimum dielectric loss of 0.045 is obtained from the sample with 8 wt% PVA. The nonlinear coefficient (α) and breakdown electric field (Eb) increase with an increase of PVA binder.

  10. Alcohol

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Alcohol KidsHealth > For Teens > Alcohol Print A A A ... you can make an educated choice. What Is Alcohol? Alcohol is created when grains, fruits, or vegetables ...

  11. Synthesis of PVA/PVP hydrogels having two-layer by radiation and their physical properties

    NASA Astrophysics Data System (ADS)

    Park, Kyoung Ran; Nho, Young Chang

    2003-06-01

    In these studies, two-layer hydrogels which consisted of polyurethane membrane and a mixture of polyvinyl alcohol(PVA)/poly- N-vinylpyrrolidone(PVP)/glycerin/chitosan were made for the wound dressing. Polyurethane was dissolved in solvent, the polyurethane solution was poured on the mould, and then dried to make the thin membrane. Hydrophilic polymer solutions were poured on the polyurethane membranes, they were exposed to gamma irradiation or two steps of 'freezing and thawing' and gamma irradiation doses to make the hydrogels. The physical properties such as gelation, water absorptivity, and gel strength were examined to evaluate the hydrogels for wound dressing. The physical properties of hydrogels such as gelation and gel strength was greatly improved when polyurethane membrane was used as a covering layer of hydrogel, and the evaporation speed of water in hydrogel was reduced.

  12. Microstructure characteristics of concrete incorporating metakaolin and PVA fibers and influence on the compressive strength

    NASA Astrophysics Data System (ADS)

    Khan, Sadaqat Ullah; Shafiq, Nasir; Ayub, Tehmina

    2015-07-01

    In this paper, microstructure of concrete is investigated using metakaolin (MK) as cement replacing material and Polyvinyl Alcohol (PVA) fibers. Total ten (10) mixes of concrete are examined by varying PVA fiber aspect ratio. It was found that MK refines the pore structure, improves interfacial transition zone (ITZ) due to its pozzolanic effects, reduces portlandite (Ca(OH)2) content and bridges the gap between matrix and aggregates due to finer particle size. Due to improvement in ITZ, the compressive strength was improved. There was no indication of Ca(OH)2 around the PVA fibers in the presence of MK and the interface between the fiber and matrix was observed very narrow.

  13. Solution parameters in the manufacture of ceramic ZnO nanofibers made by electrospinning

    NASA Astrophysics Data System (ADS)

    Nonato, Renato C.; Morales, Ana R.; Vieira, Amanda F. M.; Nista, Silvia V. G.; Mei, Lucia H. I.; Bonse, Baltus C.

    2016-03-01

    Zinc oxide (ZnO) nanofibers were prepared by electrospinning from zinc acetate (ZnAc) as precursor under different conditions. The influence of the solution parameters was studied considering type of solvent, polymer molecular weight and concentration of the components. This investigation was carried out in two stages. In the first step, a 23 factorial design was performed considering the following variables: molecular weight of poly(vinyl alcohol) (PVA), amounts of PVA and ZnAc, and water or a mix of water/alcohol as solvents. In the second step, the optimized solution of the first step was then used to create a 22 factorial design, considering the concentrations of PVA and ZnAc to improve process efficiency. The solutions were analyzed in terms of viscosity, electrical conductivity and surface tension. Fiber morphology was analyzed by scanning electron microscopy, and average diameter was determined. The formation of ZnO was evidenced by X-ray diffraction.

  14. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Haryadi, Sugianto, D.; Ristopan, E.

    2015-12-01

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm-1 and 3300 cm-1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10-2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  15. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    SciTech Connect

    Haryadi, Sugianto, D.; Ristopan, E.

    2015-12-29

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm{sup −1} and 3300 cm{sup −1} respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10{sup −2} S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant.

  16. Preparation of silver-hydroyapatite/PVA nanocomposites: Giant dielectric material for industrial and clinical applications

    NASA Astrophysics Data System (ADS)

    Uddin, Md Jamal; Middya, T. R.; Chaudhuri, B. K.

    2015-02-01

    Pure hydroxyappatite Ca10(PO4)6(OH)2 (or HAP) was prepared from eggshell and potassium dihydrogen phosphate (KH2PO4) by a simple self-chemical reaction method. The clean eggshell was heated at 800 °C in air giving the source of CaO. Appropriate amount of CaO was dissolved in KH2PO4 solution at 37°C for few days. The PH value decreases with increasing the duration of preparation of HAP. Silver nanoparticles derived from silver nitrate solution using black tea leaf extract had been introduced to hydroxyapatite due to its biocompatibility. The unique size- dependent properties of nanomaterials make them superior and indispensable. In this work, hydroxyapatite-silver nanoparticles/polyvinyl alcohol (PVA) composites with 4 different concentrations of hydroxyapatite (1-4 wt %) were prepared by bio-reduction method. Several techniques like XRD and SEM were used to characterize the prepared samples. Frequency dependent capacitance and conductance of the samples were measured using an impedance analyzer. The results showed a remarkable increase in dielectric permittivity (~5117) with low loss (~0.23) at1000 HZ and room temperature (300K) for 4wt% Hydroxapatie-Silver/PVA nanocomposite. Such nanocomposite might be directly applied in manufacturing clinical devices and also for embedding capacitor applications.

  17. Preparation and Thermal Analysis of Ferric Doped PVA-PVP-PPy Composite Films

    NASA Astrophysics Data System (ADS)

    Patil, Ravikumar V.; Ranganath, M. R.; Lobo, Blaise

    2011-12-01

    The preparation and thermal analysis of flexible blend films of pyrrole (Py) polymerized in aqueous solution of poly (vinyl alcohol) (PVA) and poly (vinyl pyrrolidone) (PVP) is described. In-situ polymerization of pyrrole in aqueous solution of PVA and PVP containing ferric chloride (FeCl3) was achieved through vapor sorption, and the films obtained were studied using Differential Scanning Calorimetry (DSC), Thermo-Gravimetric Analysis (TGA) and Differential Thermal Analysis (DTA). No melting endotherm is seen in the DSC and DTA scans of the composite films, indicating that the sample is amorphous. Degradation of the sample is found to occur at lower temperatures, with increase in doping level (wt% of FeCl3). DSC study was performed between 40 °C and 400 °C. Below 1.2 wt % DL, degradation of the sample occurs in two stages, the first at 310 °C and the second at 440 °C, as seen from DTA and TGA scans. The broad endotherm between 80 °C and 120 °C is due to volatization of moisture (water) absorbed by the sample. Multiple endotherms are observed in DSC and DTA scans of the composite films, for FeCl3 doping levels above 3.8 wt %, and the sample degrades in many different stages at lower temperature, with increase in doping level, as revealed by weight losses in the TGA curve.

  18. Synthesis of wheat straw cellulose-g-poly (potassium acrylate)/PVA semi-IPNs superabsorbent resin.

    PubMed

    Liu, Jia; Li, Qian; Su, Yuan; Yue, Qinyan; Gao, Baoyu; Wang, Rui

    2013-04-15

    To better use wheat straw and minimize its negative impact on environment, a novel semi-interpenetrating polymer networks (semi-IPNs) superabsorbent resin (SAR) composed of wheat straw cellulose-g-poly (potassium acrylate) (WSC-g-PKA) network and linear polyvinyl alcohol (PVA) was prepared by polymerization in the presence of a redox initiating system. The structure and morphology of semi-IPNs SAR were characterized by means of FTIR, SEM and TGA, which confirmed that WSC and PVA participated in the graft polymerization reaction with acrylic acid (AA). The factors that can influence the water absorption of the semi-IPNs SAR were investigated and optimized, including the weight ratios of AA to WSC and PVA to WSC, the content of initiator and crosslinker, neutralization degree (ND) of AA, reaction temperature and time. The semi-IPNs SAR prepared under optimized synthesis condition gave the best water absorption of 266.82 g/g in distilled water and 34.32 g/g in 0.9 wt% NaCl solution. PMID:23544572

  19. 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 ...

  20. Solid state solubility of miconazole in poly[(ethylene glycol)-g-vinyl alcohol] using hot-melt extrusion.

    PubMed

    Litvinov, V M; Guns, S; Adriaensens, P; Scholtens, B J R; Quaedflieg, M P; Carleer, R; Van den Mooter, G

    2012-10-01

    The use of hot-melt extrusion for preparing homogeneous API-excipient mixtures is studied for miconazole-PEG-g-PVA [poly(ethylene glycol)-poly(vinyl alcohol) graft copolymer] solid dispersions with a 5 cm(3) table-top, twin-screw corotating microcompounder (DSM Xplore). Phase behavior of PEG-g-PVA, miscibility of miconazole in PEG-g-PVA and the partitioning of miconazole between PEG and PVA amorphous phases are characterized using a combination of modulated DSC, XRPD, and solid-state (1)H and (13)C NMR methods. The (1)H NMR transverse magnetization relaxation (T(2) relaxation) method is used to analyze the phase composition and molecular mobility of the copolymer. The T(2) relaxation decay of pure PEG-g-PVA can be described by four T(2) relaxation components in the temperature range studied. PVA crystallinity is not largely affected by hot-melt extrusion and the presence of the drug. Miconazole preferably resides in the PEG amorphous phase, and its molecules are well dispersed in the PEG-g-PVA matrix using hot-melt extrusion mixing. Miconazole forms amorphous nanoclusters whose average size equals approximately 1.6 nm, indicating solid solution formation (molecular level dispersion) of the drug in the polymer. PMID:22905779

  1. Alkaline direct ethanol fuel cell performance using alkali-impregnated polyvinyl alcohol/functionalized carbon nano-tube solid electrolytes

    NASA Astrophysics Data System (ADS)

    Huang, Chien-Yi; Lin, Jia-Shiun; Pan, Wen-Han; Shih, Chao-Ming; Liu, Ying-Ling; Lue, Shingjiang Jessie

    2016-01-01

    This study investigates the application of a polyvinyl alcohol (PVA)/functionalized carbon nano-tubes (m-CNTs) composite in alkaline direct ethanol fuel cells (ADEFC). The m-CNTs are functionalized with PVA using the ozone mediation method, and the PVA composite containing the modified CNTs is prepared. Adding m-CNT into the PVA matrix enhances the alkaline uptake and the ionic conductivity of the KOH-doped electrolyte. Meanwhile, the m-CNT-containing membrane exhibited a lower swelling ratio and suppressed ethanol permeability compared to the pristine PVA film. The optimal condition for the ADEFC is determined to be under operation at an anode feed of 3 M ethanol in a 5 M KOH solution (at a flow rate of 5 cm3 min-1) with a cathode feed of moisturized oxygen (with a flow rate of 100 cm3 min-1) and the KOH-doped PVA/m-CNT electrolyte. We achieved a peak power density value of 65 mW cm-2 at 60 °C, which is the highest among the ADEFC literature data and several times higher than the proton-exchange direct ethanol fuel cells using sulfonated membrane electrolytes. Therefore, the KOH-doped PVA/m-CNT electrolyte is a suitable solid electrolyte for ADEFCs and has potential for commercialization in alkaline fuel cell applications.

  2. A tribo-mechanical analysis of PVA-based building-blocks for implementation in a 2-layered skin model.

    PubMed

    Morales Hurtado, M; de Vries, E G; Zeng, X; van der Heide, E

    2016-09-01

    Poly(vinyl) alcohol hydrogel (PVA) is a well-known polymer widely used in the medical field due to its biocompatibility properties and easy manufacturing. In this work, the tribo-mechanical properties of PVA-based blocks are studied to evaluate their suitability as a part of a structure simulating the length scale dependence of human skin. Thus, blocks of pure PVA and PVA mixed with Cellulose (PVA-Cel) were synthesised via freezing/thawing cycles and their mechanical properties were determined by Dynamic Mechanical Analysis (DMA) and creep tests. The dynamic tests addressed to elastic moduli between 38 and 50kPa for the PVA and PVA-Cel, respectively. The fitting of the creep compliance tests in the SLS model confirmed the viscoelastic behaviour of the samples with retardation times of 23 and 16 seconds for the PVA and PVA-Cel, respectively. Micro indentation tests were also achieved and the results indicated elastic moduli in the same range of the dynamic tests. Specifically, values between 45-55 and 56-81kPa were obtained for the PVA and PVA-Cel samples, respectively. The tribological results indicated values of 0.55 at low forces for the PVA decreasing to 0.13 at higher forces. The PVA-Cel blocks showed lower friction even at low forces with values between 0.2 and 0.07. The implementation of these building blocks in the design of a 2-layered skin model (2LSM) is also presented in this work. The 2LSM was stamped with four different textures and their surface properties were evaluated. The hydration of the 2LSM was also evaluated with a corneometer and the results indicated a gradient of hydration comparable to the human skin. PMID:27236420

  3. A Raman Study of Alcoholic Lithium Perchlorate Solutions in the Glassy State

    NASA Astrophysics Data System (ADS)

    Kanno, H.; Honshoh, M.; Yamauchi, S.

    1995-03-01

    Raman spectra of alcoholic lithium Perchlorate solutions (alcohol = methanol and ethanol) were measured as a function of LiClO4 concentration. The Raman band due to nearly free hydrogen bonds shows peculiar concentration dependences: (1) its frequency shifts with LiClO4 concentration in contrast to alcoholic LiX solutions (X = CI and Br), in which the Raman band due to solvated halide ions shows little frequency change with LiX concentration, and (2) the half band width shows anomalous changes with LiX concentration. Non-ionized LiClO4 species in alcohol coupled with the changes of solution structure are the major cause for this peculiar behavior.

  4. Alcohol

    MedlinePlus

    ... Text Size: A A A Listen En Español Alcohol Wondering if alcohol is off limits with diabetes? Most people with diabetes can have a moderate amount of alcohol. Research has shown that there can be some ...

  5. Alcohol

    MedlinePlus

    If you are like many Americans, you drink alcohol at least occasionally. For many people, moderate drinking ... risky. Heavy drinking can lead to alcoholism and alcohol abuse, as well as injuries, liver disease, heart ...

  6. Local, real-time measurement of drying films of aqueous polymer solutions using active microrheology.

    PubMed

    Komoda, Yoshiyuki; Leal, L Gary; Squires, Todd M

    2014-05-13

    Oscillatory microdisk rheometry was applied to evaluate the evolution of the viscoelastic properties at the surface of a film of an aqueous solution of poly(vinyl alcohol) (PVA) during drying. The drying rate was measured concurrently, based upon measurements of the variation of film thickness. A fully hydrolyzed PVA solution shows a constant drying rate, while a less hydrolyzed PVA solution exhibits a decreased drying rate in the latter part of the drying process, which occurred at the same time as an increase of the elastic modulus. We suggest that this difference in behavior is a consequence of the fact that both the configuration of the PVA molecule and the strength of interaction with water depend on the degree to which the PVA is hydrolyzed. The polymer concentration at the film surface can be estimated from the measured viscosity at the surface for the fully hydrolyzed PVA solution, and this result then can be compared with two theoretical calculations: one in which the polymer concentration is assumed to remain uniform throughout the film, and the other in which the polymer concentration distribution is determined via a one-dimensional diffusion model. This comparison suggests that the polymer is first concentrated locally near the surface but later in the drying process the distribution of polymer becomes increasingly uniform, possibly due to a spontaneously generated convective flow inside the film. PMID:24725080

  7. Development of poly(vinyl alcohol) porous scaffold with high strength and well ciprofloxacin release efficiency.

    PubMed

    Zhou, Xue-Hua; Wei, Dai-Xu; Ye, Hai-Mu; Zhang, Xiaocan; Meng, Xiaoyu; Zhou, Qiong

    2016-10-01

    Hydrophilic porous polymer scaffolds have shown great application in drug controlled release, while their mechanical properties and release efficiency still need further improvement. In the current study, the porous scaffolds of polyvinyl alcohol (PVA) prepared by quenching in liquid nitrogen and freeze drying method from different original concentration aqueous solutions were fabricated. Among different PVA scaffolds, the scaffold stemming from 18wt.% PVA aqueous solution exhibited the best mechanical properties, 10.5 and 1.54MPa tensile strengths for the dry and hydrogel states respectively. The inner morphology of such PVA scaffold was unidirectional honeycomb-like structure with average microchannel section of 0.5μm, and the scaffold showed porosity of 71% and rather low ciprofloxacin (Cip) release efficiency of 54.5%. Then poly(ethylene glycol) (PEG) was incorporated to enhance the Cip release efficiency. The release efficiency reached 89.3% after introducing 10wt.% PEG, and the mechanical properties of scaffold decreased slightly. Various characterization methods demonstrated that, adding PEG could help to enlarge the microchannel, create extra holes on the channel walls, weaken the interaction between PVA chains and Cip, and miniaturize the crystal size of Cip. All these effects benefit the dissolution and diffusion of Cip from scaffold, increasing its release capability. Moreover, based on biocompatible material composition, PVA/PEG scaffold is a non-cytotoxicity and have been verified that it can promote cell growth. And PVA/PEG scaffolds loaded with Cip can completely inhibit the growth of microorganism because of Cip sustaining release. The PVA scaffold would have a good potential application in tissue engineering, demanding high strength and well drug release capability. PMID:27287128

  8. Molecular Arrangement and Surface Tension of Alcohol Solutions.

    PubMed

    Phan, Chi M; Nguyen, Cuong V; Pham, Thuy T T

    2016-04-28

    This study investigated the relationship between molecular arrangement and surface tension of water mixtures with methanol and ethanol. It has been found that the molecular structure of interfacial zone was deterministically correlated to alcohol concentration. From the water dipole moment, an interfacial boundary was defined. The boundary then was used to calculate the water and alcohols in the interfacial zone, which was then used to calculate the surface tension. The prediction from simulated data closely followed the experimental data. The analysis revives the relevance of the molecular arrangement, which had been the main focus in the early 20th century, in quantification of surface energy. The results can supplement the current thermodynamic analysis to correctly predict the surface adsorption. PMID:27054524

  9. Electrospinning of PVA/chitosan nanocomposite nanofibers containing gelatin nanoparticles as a dual drug delivery system.

    PubMed

    Fathollahipour, Shahrzad; Abouei Mehrizi, Ali; Ghaee, Azadeh; Koosha, Mojtaba

    2015-12-01

    Nanofibrous core-sheath nanocomposite dual drug delivery system based on poly(vinyl alcohol) (PVA)/chitosan/lidocaine hydrochloride loaded with gelatin nanoparticles were successfully prepared by the electrospinning method. Gelatin nanoparticles were prepared by nanoprecipitation and were then loaded with erythromycin antibiotic agent with the average particle size of ∼175 nm. The morphology of gelatin nanoparticles observed by field emission scanning electron microscopy (FE-SEM) was shown to be optimal at the concentration of 1.25 wt % of gelatin in aqueous phase by addition of 20 µL of glutaraldehyde 5% as the crosslinking agent. The nanoparticles were also characterized by dynamic light scattering, zeta potential measurement, and Fourier transform infrared spectroscopy (FTIR). The best bead free morphology for the PVA/chitosan nanofibrous mats were obtained at the solution weight ratio of 96/4. The nanofibrous mats were analyzed by swelling studies, FTIR and antibacterial tests. In vitro dual release profile of the core-sheath nanofibers was also studied within 72 h and showed the release efficiency equal to 84.69 and 75.13% for lidocaine hydrochloride and erythromycin, respectively. According to release exponent n, the release of lidocaine hydrochloride from the sheath part of the matrix is quasi-Fickian diffusion mechanism, while the release of erythromycin is based on anomalous or non-Fickian mechanisms. PMID:26112829

  10. Spectroscopic properties of (PVA+ZnO):Mn{sup 2+} polymer films

    SciTech Connect

    Rani, Ch.; Raju, D. Siva; Bindu, S. Hima; Krishna, J. Suresh; Raju, Ch. Linga

    2015-05-15

    Electron Paramagnetic Resonance (EPR), optical absorption and infrared spectral studies have been carried out on Mn{sup 2+} ions doped in poly(vinyl alcohol) complexed with zinc oxide polymer films prepared by solution cast technique. The EPR spectra of 1 mol% Mn{sup 2+} ions doped polymer complex (PVA+ZnO) at room temperature exhibit sextet hyperfine structure (hfs), centered at 2.01. The spin-Hamiltonian parameter values indicate that the ground state of Mn{sup 2+} ion in d{sup 5} and the site symmetry around Mn{sup 2+} ions in tetragonally distorted octa hedral site. The optical absorption spectra exhibits two bands centered at 275nm at 437nm. The FTIR spectrum exhibits bands characteristic of stretching and banding vibrations of O-H, C-H and C=C groups.

  11. Characterization and mechanical performance study of silk/PVA cryogels: towards nucleus pulposus tissue engineering.

    PubMed

    Neo, Puay Yong; Shi, Pujiang; Goh, James Cho-Hong; Toh, Siew Lok

    2014-12-01

    Poly (vinyl) alcohol (PVA) cryogels are reported in the literature for application in nucleus pulposus (NP) replacement strategies. However, these studies are mainly limited to acellular approaches-in part due to the high hydrophilicity of PVA gels that renders cellular adhesion difficult. Silk is a versatile biomaterial with excellent biocompatibility. We hypothesize that the incorporation of silk with PVA will (i) improve the cell-hosting abilities of PVA cryogels and (ii) allow better tailoring of physical properties of the composite cryogels for an NP tissue engineering purpose. 5% (wt/vol) PVA is blended with 5% silk fibroin (wt/vol) to investigate the effect of silk : PVA ratios on the cryogels' physical properties. Results show that the addition of silk results in composite cryogels that are able to swell to more than 10 times its original dry weight and rehydrate to at least 70% of its original wet weight. Adding at least 20% silk significantly improves surface hydrophobicity and is correlated with an improvement in cell-hosting abilities. Cell-seeded cryogels also display an increment in compressive modulus and hoop stress values. In all, adding silk to PVA creates cryogels that can be potentially used as NP replacements. PMID:25329452

  12. Effect of polyvinyl alcohol concentration in spinning dope on diameter, beads and HHS of produced nanofibers.

    PubMed

    Khajavi, Ramin; Damerchely, Rogheih

    2007-01-15

    In this study it was aimed to produce nano fibers of poly vinyl alcohol PVA polymer via electrospinning ES method and to investigate the role of PVA concentration in the spinning dope on diameter, beads and HHS of produced fibers. Spinning dopes with different concentrations of PVA at rang of 5 to 20% (wt/wt on weight of solution) prepared. The requisite voltage for ES (30 kv) was supplied by a DC high voltage power supply and for collecting the fibers a grounded aluminum foil target placed 17 cm below the tip of capillary tube (spinning nozzle). The results showed that spinning dopes with PVA concentration between 8 to 12% (wt/wt) are capable of producing PVA fibers, but those below 8% (wt/wt) concentrations because of low viscosity formed droplets known as electrospray effect. Electrospinning suppressed at spinning dope concentrations above 12% (wt/wt) due to high viscosity of dope. According to the SEM photographs of electrospun PVA fibers it revealed that in higher concentrations produced nanofibers have larger diameter with less beads and HHS in compare with lower concentrations. PMID:19070034

  13. Biodegradable starch/poly (vinyl alcohol) film reinforced with titanium dioxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Hejri, Zahra; Seifkordi, Ali Akbar; Ahmadpour, Ali; Zebarjad, Seyed Mojtaba; Maskooki, Abdolmajid

    2013-10-01

    Biodegradable starch/poly (vinyl alcohol)/nano-titanium dioxide (ST/PVA/nano-TiO2) nanocomposite films were prepared via a solution casting method. Their biodegradability, mechanical properties, and thermal properties were also studied in this paper. A general full factorial experimental approach was used to determine effective parameters on the mechanical properties of the prepared films. ST/PVA/TiO2 nanocomposites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results of mechanical analysis show that ST/PVA films with higher contents of PVA have much better mechanical properties. In thermal analysis, it is found that the addition of TiO2 nanoparticles improves the thermal stability of the films. SEM micrographs, taken from the fracture surface of samples, illustrate that the addition of PVA makes the film softer and more flexible. The results of soil burial biodegradation indicate that the biodegradability of ST/PVA/TiO2 films strongly depends on the starch proportion in the film matrix. The degradation rate is increased by the addition of starch in the films.

  14. Steric stabilization of thermally responsive N-isopropylacrylamide particles by poly(vinyl alcohol).

    PubMed

    Lee, A; Tsai, H-Y; Yates, M Z

    2010-12-01

    Poly(vinyl alcohol) (PVA) was used as a steric stabilizer for the dispersion polymerization of cross-linked poly(N-isopropylacrylamide) (PNIPAM) in water. A series of reactions were carried out using PVA of varying molecular weight and degree of hydrolysis. Under appropriate conditions, PNIPAM particles of uniform and controllable size were produced using PVA as the stabilizer. The colloidal stability was investigated by measuring changes in particle size with temperature in aqueous suspensions of varying ionic strength. For comparison, parallel colloidal stability measurements were conducted on PNIPAM particles synthesized with low-molecular-weight ionic surfactants. PVA provides colloidal stability over a wide range of temperature and ionic strength, whereas particles produced with ionic surfactants flocculate in moderate ionic strength solutions upon collapse of the hydrogel as the temperature is increased. Experimental results and theoretical consideration indicate that sterically stabilized PNIPAM particles resulted from the grafting of PVA to the PNIPAM particle surface. The enhanced colloidal stability afforded by PVA allows the temperature-responsive PNIPAM particles to be used under physiological conditions where electrostatic stability is ineffective. PMID:21050003

  15. Mesoscopic and microscopic investigation on poly(vinyl alcohol) hydrogels in the presence of sodium decylsulfate.

    PubMed

    Mangiapia, Gaetano; Ricciardi, Rosa; Auriemma, Finizia; Rosa, Claudio De; Celso, Fabrizio Lo; Triolo, Roberto; Heenan, Richard K; Radulescu, Aurel; Tedeschi, Anna Maria; D'Errico, Gerardino; Paduano, Luigi

    2007-03-01

    The structure of poly(vinyl alcohol) (PVA) hydrogels formed as a result of freeze/thaw treatments of aqueous solutions of the polymer (11 wt % PVA) in the freshly prepared state is analyzed through the combined use of small (SANS) and ultrasmall (USANS) angle neutron scattering techniques. The structure of these hydrogels may be described in terms of polymer rich regions, with dimensions of the order of 1-2 microm, dispersed in a water rich phase, forming two bicontinuous phases. The PVA chains in the polymer rich phase form a network where the cross-linking points are mainly crystalline aggregates of PVA having average dimensions of approximately 45 A. The structural organization of freeze/thaw PVA hydrogel membranes does not change either after rehydration of dried gels or in the presence of a tensile force. Finally, addition of surfactant micelles inside the gel provides a formulation with both hydrophobic and hydrophilic regions, which demonstrates the potential of the system for drug delivery. Both SANS and EPR measurements show that sodium decylsulfate (C10OS) micelles do not significantly interact with the PVA gel. Variation of the gel structure by the number of freeze/thaw cycles should modulate the rate of release of an active constituent, for example, in a dermal patch. PMID:17295534

  16. 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. PMID:25439870

  17. A relative humidity sensing probe based on etched thin-core fiber coated with polyvinyl alcohol

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Yang, Zaihang; Zhou, Libin; Liu, Nan; Gang, Tingting; Qiao, Xueguang; Hu, Manli

    2015-12-01

    A relative humidity (RH) sensing probe based on etched thin-core fiber (TCF) coated with polyvinyl alcohol (PVA) is proposed and experimentally demonstrated.This sensor is constructed by splicing a section of TCF with a single mode fiber (SMF), then part of the TCF's cladding is etched by hydrofluoric acid solution and finally the tip of TCF is coated with PVA. Experimental results demonstrate that this sensor can measure the ambient RH by demodulating the power variation of reflection spectrum. The power demodulation method make this sensor can ignore the temperature cross-sensitivity and have an extensive application prospect.

  18. Alcohol

    MedlinePlus

    ... Got Homework? Here's Help White House Lunch Recipes Alcohol KidsHealth > For Kids > Alcohol Print A A A Text Size What's in ... What Is Alcoholism? Say No en español El alcohol Getting the Right Message "Hey, who wants a ...

  19. Enthalpic parameters of interaction between diglycylglycine and polyatomic alcohols in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Mezhevoi, I. N.; Badelin, V. G.

    2015-12-01

    Integral enthalpies of solution Δsol H m of diglycylglycine in aqueous solutions of glycerol, ethylene glycol, and 1,2-propylene glycol are measured via solution calorimetry. The experimental data are used to calculate the standard enthalpies of solution (Δsol H°) and transfer (Δtr H°) of the tripeptide from water to aqueous solutions of polyatomic alcohols. The enthalpic pairwise coefficients h xy of interactions between the tripeptide and polyatomic alcohol molecules are calculated using the McMillan-Mayer solution theory and are found to have positive values. The findings are discussed using the theory of estimating various types of interactions in ternary systems and the effect the structural features of interacting biomolecules have on the thermochemical parameters of diglycylglycine dissolution.

  20. Micro structural studies of PVA doped with metal oxide nanocomposites films

    SciTech Connect

    Kumar, N. B. Rithin; Crasta, Vincent Viju, F.; Praveen, B. M.; Shreeprakash, B.

    2014-04-24

    Nanostructured PVA polymer composites are of rapidly growing interest because of their sized-coupled properties. The present article deals with both ZnO and WO{sub 3} embedded in a polyvinyl alcohol (PVA) matrix using a solvent casting method. These films were characterized using FTIR, XRD, and SEM techniques. The FTIR spectra of the doped PVA shows shift in the bands, which can be understood on the basis of intra/inter molecular hydrogen bonding with the adjacent OH group of PVA. The phase homogeneity and morphology of the polymer composites have been analyzed using scanning electron microscope (SEM). The crystal structure and crystallinity of polymer nanocomposites were studied by X-ray diffraction technique (XRD). Thus due to the interaction of dopant and complex formation, the structural repositioning takes place and crystallinity of the nanocomposites decreases.

  1. Characterization of PbS/PVA/GQDs nanocomposite prepared by chemical bath deposition method

    NASA Astrophysics Data System (ADS)

    Tohidi, Tavakkol; Jamshidi-Ghaleh, Kazem; Mohammad-Rezaei, Rahim

    2014-10-01

    This work reports synthesis of PbS quantum dots (QDs) embedded in the poly-vinyl alcohol (PVA) in the presence of graphene quantum dots (GQDs) by the low cost and simple method of chemical bath deposition. The as-synthesized products were characterized by X-ray diffraction, transmission electron microscope and optical studies; absorption and photoluminescence measurements. Results showed that in comparison with GQDs and PbS/PVA, photoluminescence intensity of PbS/PVA/GQDs was improved and this could be attributed to rigidity of the local environment, PVA passivation and energy transformation between GQDs and PbS QDs. These analyses determined good distribution of PbS QDs on GQDs planes which is promising for practical applications in nanotechnology.

  2. Fabrication and photocatalytic performance of electrospun PVA/silk/TiO2 nanocomposite textile

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Chung; Chan, Shun-Hsiang; Lin, Ting-Han

    2015-02-01

    Many organic/inorganic nanocomposites have been fabricated into fibrous materials using electrospinning techniques, because electrospinning processes have many attractive advantages and the ability to produce relatively large-scale continuous films. In this study, the polyvinyl alcohol (PVA)/silk/titanium dioxide (TiO2) nanocomposite self-cleaning textiles were successfully produced using electrospinning technique. After optimizing electrospinning conditions, we successfully obtained the PVA/silk/TiO2 nanocomposite fibers with average diameter of ˜220 nm and TiO2 concentration can be as high as 18.0 wt.%. For the case of the PVA/silk/TiO2 nanocomposite textile, the color of brilliant green coated on the textile surface changed from the initial green color to colorless after ultraviolet (UV) irradiation. Because of its worthy photocatalytic performance, the developed PVA/silk/TiO2 nanocomposite materials in this study will be beneficial for the design and fabrication of multifunctional fibers and textiles.

  3. Influence of Al doping on optical properties of CdS/PVA nanocomposites: Theory and experiment

    SciTech Connect

    Bala, Vaneeta Tripathi, S. K. Kumar, Ranjan

    2014-04-24

    In the present work theoretical and experimental studies of aluminium doped cadmium sulphide polyvinyl alcohol (Al:CdS/PVA) nanocomposites have been carried out. Tetrahedral cluster AlCd{sub 9}S{sub 2}(SH){sub 18}]{sup 1−} has been encapsulated by small segments of polyvinyl alcohol (PVA) chains in order to simulate experimental environment of nanocomposites. Density functional theory (DFT) using local density approximation (LDA) functionals is employed to study the broadening of band gap upon ligation of nanoclusters. We have used in situ chemical route to synthesize nanocomposites. Optical band gap has been calculated from both experimental and theoretical approach.

  4. Heat resistance poly(vinyl alcohol) hydrogel

    NASA Astrophysics Data System (ADS)

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

    1995-08-01

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

  5. An E-Health Solution for People With Alcohol Problems

    PubMed Central

    Gustafson, David H.; Boyle, Michael G.; Shaw, Bret R.; Isham, Andrew; McTavish, Fiona; Richards, Stephanie; Schubert, Christopher; Levy, Michael; Johnson, Kim

    2011-01-01

    Self-management of chronic diseases has been a research focus for years. Information and communication technologies (ICTs) have played a significant role in aiding patients and their families with that management task. The recent dramatic increase in smartphone capabilities has expanded the potential of these technologies by facilitating the integration of features specific to cell phones with advanced capabilities that extend the reach of what type of information can be assessed and which services can be provided. A recent review of the literature covering the use of ICTs in managing chronic diseases, including addiction, has examined the effectiveness of ICTs, with an emphasis on technologies tested in randomized controlled trials. One example of an addiction-relapse prevention system currently being tested is the Alcohol Comprehensive Health Enhancement Support System (A-CHESS) Program. PMID:23293549

  6. An e-health solution for people with alcohol problems.

    PubMed

    Gustafson, David H; Boyle, Michael G; Shaw, Bret R; Isham, Andrew; McTavish, Fiona; Richards, Stephanie; Schubert, Christopher; Levy, Michael; Johnson, Kim

    2011-01-01

    Self-management of chronic diseases has been a research focus for years. Information and communication technologies (ICTs) have played a significant role in aiding patients and their families with that management task. The recent dramatic increase in smartphone capabilities has expanded the potential of these technologies by facilitating the integration of features specific to cell phones with advanced capabilities that extend the reach of what type of information can be assessed and which services can be provided. A recent review of the literature covering the use of ICTs in managing chronic diseases, including addiction, has examined the effectiveness of ICTs, with an emphasis on technologies tested in randomized controlled trials. One example of an addiction-relapse prevention system currently being tested is the Alcohol Comprehensive Health Enhancement Support System (A-CHESS) Program. PMID:23293549

  7. Design strategies for 157-nm single-layer photoresists: lithographic evaluation of a poly(α -trifluoromethyl vinyl alcohol) copolymer

    NASA Astrophysics Data System (ADS)

    Schmaljohann, Dirk; Bae, Young C.; Weibel, Gina L.; Hamad, Alyssandrea H.; Ober, Christopher K.

    2000-06-01

    Poly(vinyl alcohol-co-(alpha) -trifluoromethyl vinyl alcohol) (PVA-co-CF3PVA) protected with an acid cleavable group was prepared as a single-layer photoresist for use in 157 nm VUV lithography. It was found that the (alpha) -trifluoromethyl substituent renders PVA-co-CF3PVA readily soluble in 0.262 N TMAH. The protected polymer can be spin-coated from PGMEA and preliminary studies using 248 nm exposure showed a THP protected PVA-co-CF3PVA undergoes chemically amplified deprotection with a clearing dose of approximately 15 mJ/cm2. Using a VUV spectrometer, absorption coefficients of approximately 3 micrometer-1 were observed at 157 nm with PVA-co-CF3PVA and THP protected PVA-co-CF3PVA. Detailed lithographic evaluation of the polymer is underway and design strategies for 157 nm single-layer photoresists will be discussed.

  8. Effect of cross linking of PVA/starch and reinforcement of modified barley husk on the properties of composite films.

    PubMed

    Mittal, Aanchal; Garg, Sangeeta; Kohli, Deepak; Maiti, Mithu; Jana, Asim Kumar; Bajpai, Shailendra

    2016-10-20

    Barley husk (BH) was graft copolymerized by palmitic acid. The crystalline behavior of BH decreased after grafting. Poly vinyl alcohol (PVA)/starch (St) blend film, urea formaldehyde cross linked PVA/St films and composite films containing natural BH, grafted BH were prepared separately. The effect of urea/starch ratio, content of BH and grafted BH on the mechanical properties, water uptake (%), and biodegradability of the composite films was observed. With increase in urea: starch ratio from 0 to 0.5 in the blend, tensile strength of cross linked film increased by 40.23% compared to the PVA/St film. However, in grafted BH composite film, the tensile strength increased by 72.4% than PVA/St film. The degradation rate of natural BH composite film was faster than PVA/St film. Various films were characterized by SEM, FT-IR and thermal analysis. PMID:27474641

  9. Measurement of Temperature Dependence of Surface Tension of Alcohol Aqueous Solutions by Maximum Bubble Pressure Method

    NASA Astrophysics Data System (ADS)

    Ono, Naoki; Kaneko, Takahiro; Nishiguchi, Shotaro; Shoji, Masahiro

    The surface tension of some high-carbon alcohol aqueous solutions increases as the temperature rises above a certain temperature. There have been attempts to use such special solutions in thermal devices to promote heat transfer. In this study, the authors analyzed the temperature dependence of surface tension of these solutions to investigate this peculiar characteristic in detail. The test fluids were butanol and pentanol aqueous solutions as peculiar solutions, while pure water and ethanol aqueous solution were normal fluids. First, the authors adopted Wilhelmy's method to measure the surface tension during heating, but found that the influence of evaporation of the solution could not be completely eliminated. In this study, the maximum bubble pressure method was employed, which made it possible to isolate the measured solution from ambient air and eliminate the influence of evaporation of the solution. The authors succeeded in measuring the temperature dependence of surface tension, and obtained more reasonable data.

  10. Alcohol

    MedlinePlus

    ... as well as injuries, liver disease, heart disease, cancer, and other health problems. It can also cause problems at home, at work, and with friends. NIH: National Institute on Alcohol Abuse and Alcoholism

  11. Alcoholism.

    ERIC Educational Resources Information Center

    Caliguri, Joseph P., Ed.

    This extensive annotated bibliography provides a compilation of documents retreived from a computerized search of the ERIC, Social Science Citation Index, and Med-Line databases on the topic of alcoholism. The materials address the following areas of concern: (1) attitudes toward alcohol users and abusers; (2) characteristics of alcoholics and…

  12. DBS investigation on films of cobalt chloride doped PVA-PVP blend

    NASA Astrophysics Data System (ADS)

    Hammannavar, Preeti B.; Baraker, Basavarajeshwari M.; Bhajantri, R. F.; Ravindrachary, V.; Lobo, Blaise

    2015-06-01

    Films of Cobalt Chloride (CoCl2) doped polyvinylalcohol(PVA)- polyvinylpyrrolidone(PVP) blend (doped from 0.5 wt% up to 28 wt%) were prepared by solution casting, and characterized by XRD, DSC, UV-Visible Spectrometry TGA, FTIR and electrical measurements. In this paper, the results of Doppler Broadening Spectroscopy (DBS) in CoCl2 doped PVA-PVP blend is discussed. An increase in crystallinity of PVA-PVP blend, is observed, on doping it with CoCl2. The DBS results are complemented by XRD and DSC scans.

  13. Gelation Behavior of 5-Chloro-8-hydroxyquinoline, an Antituberculosis Agent in Aqueous Alcohol Solutions

    PubMed Central

    Kolehmainen, Erkki; Salo, Hannu; Korpela, Jukka

    2012-01-01

    It was shown that 5-chloro-8-hydroxyquinoline, an antituberculosis agent, gels aqueous alcohol solutions efficiently. Thermal stability and gel-to-sol transition temperature of 1% gel in CD3OD/D2O (2:1) was studied by 1H-NMR. Fibrous structures of four xerogels have been characterized by scanning electron microscope. PMID:27029417

  14. Investigations on the predictability of the formation of glassy solid solutions of drugs in sugar alcohols.

    PubMed

    Langer, M; Höltje, M; Urbanetz, N A; Brandt, B; Höltje, H-D; Lippold, B C

    2003-02-18

    A prerequisite for the formation of glassy solid solutions prepared by the melting method is the miscibility of the respective drug and the carrier in the molten state. As could be shown experimentally, all investigated drug/sugar alcohol combinations miscible in the molten state form to some extent glassy solid solutions, dependent on their tendency to recrystallize during preparation. Therefore, the present study focuses on the evaluation of factors that govern the miscibility of molten drugs and sugar alcohols as carriers. In this context, solubility parameters are discussed as a means of predicting miscibility in comparison to a new approach, using calculated interaction parameters derived from molecular dynamics (MD) studies. There is evidence that a Coulomb interaction term C(SR), comprising short-range electrostatic interactions and hydrogen bonding energy is essential for the miscibility of drug and carrier in the molten state. To relate C(SR) to the molecular volume, a non-dimensional parameter P(i) is defined. For this parameter, a limiting value for miscibility exists. Contrary, calculated solubility parameter differences between drug and sugar alcohol in the range of 8-15 MPa(1/2) are not suitable for a prediction of miscibility or immiscibility, since the mixtures deviate from regular solution behavior. In irregular mixtures of drugs and sugar alcohols, an excess entropy and the formation of hydrogen bonds between unlike molecules favor miscibility, that cannot be predicted by regular solution theory. PMID:12550792

  15. 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.

  16. A reduction of diffusion in PVA Fricke hydrogels

    NASA Astrophysics Data System (ADS)

    Smith, S. T.; Masters, K. S.; Hosokawa, K.; Blinco, J.; Crowe, S. B.; Kairn, T.; Trapp, J. V.

    2015-01-01

    A modification to the PVA-FX hydrogel whereby the chelating agent, xylenol orange, was partially bonded to the gelling agent, poly-vinyl alcohol, resulted in an 8% reduction in the post irradiation Fe3+ diffusion, adding approximately 1 hour to the useful timespan between irradiation and readout. This xylenol orange functionalised poly-vinyl alcohol hydrogel had an OD dose sensitivity of 0.014 Gy-1 and a diffusion rate of 0.133 mm2 h-1. As this partial bond yields only incremental improvement, it is proposed that more efficient methods of bonding xylenol orange to poly-vinyl alcohol be investigated to further reduce the diffusion in Fricke gels.

  17. Effects of PVA-coated nanoparticles on human T helper cell activity.

    PubMed

    Strehl, Cindy; Schellmann, Saskia; Maurizi, Lionel; Hofmann-Amtenbrink, Margarethe; Häupl, Thomas; Hofmann, Heinrich; Buttgereit, Frank; Gaber, Timo

    2016-03-14

    Superparamagnetic iron oxide nanoparticles (SPION) are used as high-sensitive enhancer for magnetic resonance imaging, where they represent a promising tool for early diagnosis of destructive diseases such as rheumatoid arthritis (RA). Since we could demonstrate that professional phagocytes are activated by amino-polyvinyl-alcohol-coated-SPION (a-PVA-SPION), the study here focuses on the influence of a-PVA-SPION on human T cells activity. Therefore, primary human CD4+ T cells from RA patients and healthy subjects were treated with varying doses of a-PVA-SPION for 20h or 72h. T cells were then analyzed for apoptosis, cellular energy, expression of the activation marker CD25 and cell proliferation. Although, we observed that T cells from RA patients are more susceptible to low-dose a-PVA-SPION-induced apoptosis than T cells from healthy subjects, in both groups a-PVA-SPION do not activate CD4+ T cells per se and do not influence mitogen-mediated T cells activation with regard to CD25 expression and cell proliferation. Nevertheless, our results demonstrate that CD4+ T cells from RA patients and healthy subjects differ in their response to mitogen stimulation and oxygen availability. We conclude from our data, that a-PVA-SPION do neither activate nor significantly influence mitogen-stimulated CD4+ T cells activation and have negligible influence on T cells apoptosis. PMID:26774940

  18. Pervaporation separation of binary organic-aqueous liquid mixtures using crosslinked PVA membranes. I. Characterization of the reaction between PVA and PAA

    SciTech Connect

    Jiwon Rhim; Kewho Lee . Membranes and Separation Lab.); Minyoung Sohn; Hyeokjong Joo . Dept. of Polymer Science and Engineering)

    1993-10-20

    For the purpose of the water-selective membrane material development for pervaporation separation, poly(vinyl alcohol) (PVA) was crosslinked with a low molecular weight of poly(acrylic acid) (PAA). The crosslinking reactions between PVA and PAA were characterized through IR spectroscopy, differential scanning calorimetry (DSC), and tensile tests when varying the reaction conditions, that is, time, temperature, amounts of cross-linking agents, PAA. It was found that the crosslinking reaction was fast: in other words, that the reaction mainly occurred at the initial step of each reaction condition. The best reaction conditions for preparing the crosslinked PVA membranes were found to be: reaction time not over 1 h, reaction temperature in the range of 150-180 C. PAA contents of 15-20 wt% were found satisfactory with respect to the application areas.

  19. Antibacterial silver nanoparticles in polyvinyl alcohol/sodium alginate blend produced by gamma irradiation.

    PubMed

    Eghbalifam, Naeimeh; Frounchi, Masoud; Dadbin, Susan

    2015-09-01

    Polyvinyl alcohol/sodium alginate/nano silver (PVA/SA/Ag) composite films were made by solution casting method. Gamma irradiation was used to synthesize silver nanoparticles in situ via reduction of silver nitrate without using harmful chemical agents for biomedical applications. UV-vis and XRD results demonstrated that spherical silver nanoparticles were produced even at low irradiation dose of 5 kGy. By increasing irradiation dose, more nanoparticles were synthesized while no PVA hydrogel was formed up to 15 kGy. Also the size of nanoparticles was reduced with increasing gamma dose evidenced by higher release rate of silver nanoparticles in lukewarm water and SEM images. Comparing SEM images with DLS results indicated good performance of PVA/SA as an efficient stabilizer in preventing agglomeration of the silver nanoparticles. Good miscibility of polyvinyl alcohol and sodium alginate observed on the SEM images was supported with FTIR spectroscopy. Upon addition of sodium alginate to polyvinyl alcohol and increasing silver nanoparticles, the melting peak shifted to lower temperature and crystallinity percent was decreased. Addition of sodium alginate led to remarkable increase in rigidity of PVA. The composites exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli even at very low level of silver nanoparticles. PMID:26123816

  20. Synergistic effect of ozonation and ionizing radiation for PVA decomposition.

    PubMed

    Sun, Weihua; Chen, Lujun; Zhang, Yongming; Wang, Jianlong

    2015-08-01

    Ozonation and ionizing radiation are both advanced oxidation processes (AOPs) without chemical addition and secondary pollution. Also, the two processes' efficiency is determined by different pH conditions, which creates more possibilities for their combination. Importantly, the combined process of ozonation and ionizing radiation could be suitable for treating wastewaters with extreme pH values, i.e., textile wastewater. To find synergistic effects, the combined process of ozonation and ionizing radiation mineralization was investigated for degradation of polyvinyl alcohol (PVA) at different pH levels. A synergistic effect was found at initial pH in the range 3.0-9.4. When the initial pH was 3.0, the combined process of ozonation and ionizing radiation gave a PVA mineralization degree of 17%. This was 2.7 times the sum achieved by the two individual processes, and factors of 2.1 and 1.7 were achieved at initial pH of 7.0 and 9.4, respectively. The combined process of ozonation and ionizing radiation was demonstrated to be a feasible strategy for treatment of PVA-containing wastewater. PMID:26257347

  1. A comparison of flexural strengths of polymer (SBR and PVA) modified, roller compacted concrete

    PubMed Central

    Karadelis, John N.; Lin, Yougui

    2015-01-01

    This brief article aims to reveal the flexural performance, including the equivalent flexural strength of PVA (Polyvinyl Alcohol) modified concrete by comparing it primarily with that of SBR (Styrene Butadiene Rubber) concrete. This data article is directly related to Karadelis and Lin [6]. PMID:26306313

  2. A comparison of flexural strengths of polymer (SBR and PVA) modified, roller compacted concrete.

    PubMed

    Karadelis, John N; Lin, Yougui

    2015-09-01

    This brief article aims to reveal the flexural performance, including the equivalent flexural strength of PVA (Polyvinyl Alcohol) modified concrete by comparing it primarily with that of SBR (Styrene Butadiene Rubber) concrete. This data article is directly related to Karadelis and Lin [6]. PMID:26306313

  3. Livestock Air Treatment Using PVA-Coated Powdered Activated Carbon Biofilter

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ideal biofilter media provide surface for attachment of microorganisms responsible for removing air-born contaminants while facilitating passage of air. This study evaluated the efficacy of polyvinyl alcohol (PVA)-coated powdered activated carbon particles as a biofiltration medium. This material e...

  4. [Research on the treatment of wastewater containing PVA by ozonation-activated sludge process].

    PubMed

    Xing, Xiao-Qiong; Huang, Cheng-Lan; Liu, Min; Chen, Ying

    2012-11-01

    The wastewater containing polyvinyl alcohol (PVA) was characterized with poor biodegradability, and was difficult to remove. In order to find an economically reasonable and practical technology, the research on the removal efficiency of different concentration wastewater containing PVA by ozonation-activated sludge process was studied, and the result was compared with the traditional activated sludge process. The results showed that the ozonation-activated sludge process was not suitable for treating influent with COD below 500 mg x L(-1) and the wastewater PVA concentration was 10-30 mg x L(-1). When the influent COD was between 500-800 mg x L(-1) and the PVA concentration was 15-60 mg x L(-1), the system had advantages on dealing with this kind of wastewater, and the average removal efficiency of COD and PVA were 92.8% and 57.4%, which were better than the traditional activated sludge process 4.1% and 15.2% respectively. In addition, the effluent concentrations of COD could keep between 30-60 mg x L(-1). When the influent COD was 1 000-1 200 mg x L(-1) and the PVA concentration was 20-70 mg x L(-1), the average removal efficiencies of COD and PVA were 90.9% and 45.3%, which were better than the traditional activated sludge process 12.8% and 12.1% respectively, but the effluent should to be further treated. Compared with the traditional activated sludge process, ozonation-activated sludge process had high treatment efficiency, stable running effect, and effectively in dealing with industrial wastewater containing PVA. PMID:23323416

  5. Surface Tension Characteristics of Aqueous Lithium Bromide Solution with Alcoholic Surfactant

    NASA Astrophysics Data System (ADS)

    Sasaki, Naoe; Ogawa, Kiyoshi

    At present, the combination of aqueous lithium bromide (LiBr) solution as an absorbent and water as a refrigerant have widely been used as the working fluid for absorption refrigerating machines. In order to obtain absorption enhancement of water vapor into the LiBr solution by Marangoni convection, an alcoholic surfactant is being added in the LiBr solution. In that case, the surface tension of the LiBr solution with the surfactant plays an important role for the vapor absorption. In this study, the surface tensions of the LiBr solution with several alcoholic surfactants such as 1-butanol, 1-hexanol, 2-ethyl-1-butanol, 2-methyl-1-pentanol, 1-heptanol, 1-octanol and 2-ethyl-1-hexanol were measured by Wilhelmy plate method. As a result, the surface tensions of 50 wt% LiBr solution with several surfactants were obtained over the LiBr solution temperature range from 298 K to 318 K and the surfactant concentration range from 0 to 104 ppm by mass. The measured surface tension has decreased with the increasing number of carbons included in the surfactant at constant concentration, and the surface tension has increased with the increasing temperature of 50 wt% LiBr solution. The surface tension increase of 1-octanol became greater than any other surfactant used in this work. The effective carbon number of the surfactant for the absorption enhancement was in the range from 7 to 8.

  6. Comparative bio-safety and in vivo evaluation of native or modified locust bean gum-PVA IPN microspheres.

    PubMed

    Kaity, Santanu; Ghosh, Animesh

    2015-01-01

    Strategically developed natural polymer-based controlled release multiparticulate drug delivery systems have gained special interest for “spatial placement” and “temporal delivery” of drug molecules. In our earlier study, locust bean gum-poly(vinyl alcohol) interpenetrating polymer network (LBG-PVA IPN), carboxymethylated locust bean gum-poly(vinyl alcohol) interpenetrating polymer network (CMLBG-PVA IPN) and acrylamide grafted locust bean gum-poly(vinyl alcohol) interpenetrating polymer network (Am-g-LBG-PVA IPN) were prepared and characterized. The present study deals with accelerating stability testing, comparative bio-safety and single dose in vivo pharmacokinetic study of all three IPN microspheres for controlled oral delivery of buflomedil hydrochloride (BH). From the stability study, it was observed that the particles were stable throughout the study period. From toxicity and biodegradability study it was proved that the microspheres were safe for internal use and complied with bio-safety criterion. From the in vivo pharmacokinetic study in rabbits, it was observed that the CMLBG-PVA IPN microspheres possessed almost similar Tmax value with BH oral suspension. However, in comparison between the LBG-PVA and Am-g-LBG-PVA IPN microspheres, the later showed well controlled release property than the first in biological condition. Thus, this type of delivery system might be useful to achieve the lofty goals of the controlled release drug delivery. PMID:25307127

  7. Functionalized graphene oxide quantum dot-PVA hydrogel: a colorimetric sensor for Fe²⁺, Co²⁺ and Cu²⁺ ions.

    PubMed

    Baruah, Upama; Chowdhury, Devasish

    2016-04-01

    Functionalized graphene oxide quantum dots (GOQDs)-poly(vinyl alcohol) (PVA) hybrid hydrogels were prepared using a simple, facile and cost-effective strategy. GOQDs bearing different surface functional groups were introduced as the cross-linking agent into the PVA matrix thereby resulting in gelation. The four different types of hybrid hydrogels were prepared using graphene oxide, reduced graphene oxide, ester functionalized graphene oxide and amine functionalized GOQDs as cross-linking agents. It was observed that the hybrid hydrogel prepared with amine functionalized GOQDs was the most stable. The potential applicability of using this solid sensing platform has been subsequently explored in an easy, simple, effective and sensitive method for optical detection of M(2+) (Fe(2+), Co(2+) and Cu(2+)) in aqueous media involving colorimetric detection. Amine functionalized GOQDs-PVA hybrid hydrogel when put into the corresponding solution of Fe(2+), Co(2+) and Cu(2+) renders brown, orange and blue coloration respectively of the solution detecting the presence of Fe(2+), Co(2+) and Cu(2+) ions in the solution. The minimum detection limit observed was 1 × 10(-7) M using UV-visible spectroscopy. Further, the applicability of the sensing material was also tested for a mixture of co-existing ions in solution to demonstrate the practical applicability of the system. Insight into the probable mechanistic pathway involved in the detection process is also being discussed. PMID:26902906

  8. Fabrication and characterization of poly(vinyl alcohol)-TiO2 nanocomposite films for orthopedic applications.

    PubMed

    Mohanapriya, S; Mumjitha, M; PurnaSai, K; Raj, V

    2016-10-01

    Poly(vinyl alcohol) (PVA) is reinforced with TiO2 nanoparticles in order to enhance thermo-mechanical stabilities, surface characteristics and osteoblastic cell adhesion. PVA-TiO2 nanocomposite films with desirable mechanical, thermal and biocompatible properties are fabricated through solution casting method followed by de-hydrothermal cross-linking treatment. The composition of TiO2 nanoparticles was standardized to achieve mechanically stable nanocomposite films, based on tensile strength measurements composition of TiO2 is determined as optimal at 3wt%. PVA-TiO2 nanocomposite films were characterized by Scanning electron microscopy, Energy dispersive spectroscopy, Atomic force microscopy, Ultra violet and Fourier transform infrared spectroscopic techniques. Elemental mapping studies substantiate incorporation of TiO2 nanoparticles within the PVA matrix. Dimensional stability evaluated by soaking films in SBF for 24h insinuates the role of TiO2 in the direction of controlling degree of swelling. In-vitro bioactivity test and cell adhesion results also predict that presence of TiO2 is advantageous to enhance apatite growth and promote cell-substrate interaction. SEM studies illustrate improved surface morphology of PVA-TiO2 nanocomposite film with homogenously distributed TiO2 nanoparticles, which help to enhance thermo-mechanical behavior. TiO2 nanoparticles construct cell-adhesive hydrophilic nano-domains that act as potential cell adhesion sites and promotes osteointegration. Bio compatibility studies proved that thermally cross-linked PVA is non-toxic in relation to PVA cross-linked with glutaraldehyde. Cytotoxicity and cell adhesion of nanocomposite films evaluated through cell viability (MMT) assay and crystal violet staining revealed that PVA-3wt% TiO2nanocomposite could act as an excellent composite and hence suitable to be used in bone implant applications. PMID:27371870

  9. 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

  10. Mechanism of sonochemical reduction of permanganate to manganese dioxide in aqueous alcohol solutions: Reactivities of reducing species formed by alcohol sonolysis.

    PubMed

    Okitsu, Kenji; Iwatani, Masaki; Okano, Koji; Uddin, Md Helal; Nishimura, Rokuro

    2016-07-01

    The sonochemical reduction of MnO4(-) to MnO2 in aqueous solutions was investigated as a function of alcohol concentration under Ar. The rate of MnO4(-) reduction initially decreased with increasing alcohol concentration, and then increased when the alcohol concentration was increased further. The concentrations at which the reduction rates were minimum depended on the hydrophobic properties of the added alcohols under ultrasonic irradiation. At low concentrations, the alcohols acted as OH radical scavengers; at high concentrations, they acted as reductant precursors: Rab, formed by abstraction reactions of the alcohols with sonochemically formed OH radicals or H atoms, and Rpy, formed by alcohol pyrolysis under ultrasonic irradiation. The results suggest that the reactivity order of the sonochemically formed reducing species with MnO4(-) at pH 7-9 is the sum of H2O2 and H>Rpy>Rab. The peak wavelengths of MnO2 colloidal solutions formed at high 1-butanol concentrations shifted to shorter wavelengths, suggesting the formation of small particles at high 1-butanol concentrations. The rates of sonochemical reduction of MnO2 to Mn(2+) in the presence of 1-butanol were slower than that in the absence of 1-butanol, because the sonochemical formation of H2O2 and H, which act as reductants, was suppressed by 1-butanol in aqueous solutions. PMID:26964972

  11. Thermodynamics of alcohols and monosaccharides in aqueous solutions of biuret at 25/sup 0/C

    SciTech Connect

    Barone, G.; Castronuovo, G.; Del Vecchio, P.; Elia, V.; Tosto, M.T.

    1988-10-01

    The excess enthalpies of ternary aqueous solutions of biuret with four aliphatic alcohols or four isomeric pentoses have been determined by flow microcalorimetry at 25/sup 0/C. The coefficients of the virial expansion of the excess enthalpies have been evaluated and compared with those already reported for urea and thiourea with the same alcohols and pentoses used here. For biuret-alcohol systems, the cross coefficients are positive and depend on the length and branching of the alkyl chain of the alcohols. On the contrary, they are negative for biuret-pentose systems. Hence, biuret, as urea and thiourea, is able to differentiate the behavior of families of solutes characterized by the same functional groups. The results are interpreted in terms of the relative stabilities of the hydration cospheres of predominantly hydrophobic or predominantly hydrophilic cosolutes. However, hypotheses about the hydration cospheres of the saccharides, which are more complex than those used previously, seem to be necessary to rationalize their complete behavior in water.

  12. Whole-Pattern Fitting and Positron Annihilation Studies of Magnetic PVA/α-Fe2O3 Nanocomposites

    NASA Astrophysics Data System (ADS)

    Prashanth, K. S.; Mahesh, S. S.; Prakash, M. B. Nanda; Ningaraju, S.; Ravikumar, H. B.; Somashekar, R.; Nagabhushana, B. M.

    2016-03-01

    A low-temperature solution combustion method was used to synthesize α-Fe2O3 nanoparticles. Magnetic polyvinyl alcohol (PVA)/α-Fe2O3/NaCl nanocomposites were prepared by solvent cast method. The Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) results are in confirmation with X-ray diffraction (XRD) results indicating the formation of nanocomposites. The microcrystalline parameters, crystallite size (), lattice strain (g in %), stacking faults (α d ), and twin faults (β) of prepared polymer nanocomposites were evaluated by whole-pattern fitting technique. The refinement was carried out using the computed microstructural parameters in which the twin faults and stacking faults did not vary much and statistical deviation was less than 5 %. Positron annihilation lifetime spectroscopy (PALS) was used for microstructural characterization. PALS results show that the ortho-positronium (o-Ps) lifetime (τ3) increases gradually as a function of nanoparticle concentration and about 219 ps increase observed from1.50 to1.71 ns at 3 wt%. This indicates the increase of free volume hole size (V f ) from 54.47 to 72.18 Å3. The o-Ps intensities (I 3) decrease indicating the inhibition of o-Ps formation upon incorporation of nanoparticles into PVA. The increase in I 2 values suggests the increased annihilation at the interface region. Positron lifetime parameters, viz., o-Ps lifetime, and its intensities indicate the effect of quenching and inhibition upon incorporation of metal oxide nanoparticles and inorganic salt into PVA.

  13. Whole-Pattern Fitting and Positron Annihilation Studies of Magnetic PVA/α-Fe2O3 Nanocomposites

    NASA Astrophysics Data System (ADS)

    Prashanth, K. S.; Mahesh, S. S.; Prakash, M. B. Nanda; Ningaraju, S.; Ravikumar, H. B.; Somashekar, R.; Nagabhushana, B. M.

    2016-06-01

    A low-temperature solution combustion method was used to synthesize α-Fe2O3 nanoparticles. Magnetic polyvinyl alcohol (PVA)/α-Fe2O3/NaCl nanocomposites were prepared by solvent cast method. The Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) results are in confirmation with X-ray diffraction (XRD) results indicating the formation of nanocomposites. The microcrystalline parameters, crystallite size ( ), lattice strain ( g in %), stacking faults ( α d ), and twin faults ( β) of prepared polymer nanocomposites were evaluated by whole-pattern fitting technique. The refinement was carried out using the computed microstructural parameters in which the twin faults and stacking faults did not vary much and statistical deviation was less than 5 %. Positron annihilation lifetime spectroscopy (PALS) was used for microstructural characterization. PALS results show that the ortho-positronium (o-Ps) lifetime (τ3) increases gradually as a function of nanoparticle concentration and about 219 ps increase observed from1.50 to1.71 ns at 3 wt%. This indicates the increase of free volume hole size ( V f ) from 54.47 to 72.18 Å3. The o-Ps intensities ( I 3) decrease indicating the inhibition of o-Ps formation upon incorporation of nanoparticles into PVA. The increase in I 2 values suggests the increased annihilation at the interface region. Positron lifetime parameters, viz., o-Ps lifetime, and its intensities indicate the effect of quenching and inhibition upon incorporation of metal oxide nanoparticles and inorganic salt into PVA.

  14. Synthesis, characterization and nonlinear optical properties of silver/PVA nanocomposites

    NASA Astrophysics Data System (ADS)

    Faraji, N.; Mahmood Mat Younus, W.; Kharazmi, A.; Saion, E.; Shahmiri, M.; Tamchek, N.

    2012-09-01

    Silver/polyvinyl alcohol (PVA) nanocomposites are prepared via quick precipitation method, using hydrazine as a reducing agent. Preparing of silver/PVA nanocomposites by this method is done for the first time. The samples are characterized by Uv-Visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM). Nonlinear optical properties are carried out by Z-scan technique using a blue CW laser beam operated at wavelength 405 nm. It is shown that the synthesized samples have negative nonlinear refractive index and the magnitude is in the order of 10^-8. The nonlinear refractive index increases as amount of reducing agent increases.

  15. The sporicidal activity and inactivation of chlorhexidine gluconate in aqueous and alcoholic solution.

    PubMed

    Gorman, S P; Jones, D S; Loftus, A M

    1987-08-01

    The sporicidal activity of chlorhexidine gluconate in aqueous and alcoholic solution against spores of Bacillus subtilis was examined over a broad temperature range. Activity was not observed at 20 degrees C even with concentrations as high as 10% chlorhexidine. Temperatures of 37 degrees-70 degrees C in combination with such high concentrations were required for reductions in spore viability. No viable spores were recoverable after 4 h contact at 55 degrees C with 10% aqueous chlorhexidine and none after 3 h contact with the alcoholic solution. Because of the high concentrations necessary for activity and the possibility of sporostasis occurring from inefficient chlorhexidine inactivation, existing inactivation systems were examined and modified to obtain satisfactory results. The spores of other Bacillus species examined (B. cereus, B. megaterium and B. stearothermophilus) proved to be considerably less resistant than those of B. subtilis. Presence of organic matter had little effect on the activity. PMID:3115938

  16. Modification of Novel Conductive PEDOT:Sulfonated Polyimide Nano-Thin Films by Anionic Surfactant and Poly(vinyl alcohol) for Electronic Applications

    NASA Astrophysics Data System (ADS)

    Romyen, Nathavat; Thongyai, Supakanok; Praserthdam, Piyasan; Sotzing, Gregory A.

    2013-12-01

    Conductive poly(3,4-ethylenedioxythiophene):sulfonated polyimide (PEDOT: SPI) nanoscale thin films were successfully developed by addition of anionic surfactant and poly(vinyl alcohol) (PVA) for potential application in electronic devices. In this work, sodium dodecyl sulfate (SDS) surfactant was introduced into PEDOT:SPI aqueous suspensions to improve the dispersion stability of the particles in water, leading to high transparency and low contact angle of PEDOT:SPI thin films. All of the conducting polymer thin films showed high transparency of more than 85% transmission. Conductivity enhancement and good film-formation properties of PEDOT:SPI were achieved by adding various amounts of PVA to each polymer aqueous suspension because of the resulting conformational changes. The highest conductivity of 0.134 S/cm was achieved at 0.08 wt.% PVA in PEDOT:SPI2/SDS/PVA film, increased by a factor of 3.5 compared with the original material. In addition, PVA also improved the thermal stability of the conductive films, as verified by thermogravimetric analysis (TGA). The interactions between conducting polymers, PVA, and SDS surfactant affecting nano-thin film properties were revealed and investigated. Moreover, the interactions between SDS and SPI were proven to be different from those between SDS and poly(styrenesulfonate) (PSS) in conventional PEDOT:PSS solutions.

  17. Determination of glass transition temperature of reduced graphene oxide-poly(vinyl alcohol) composites using temperature dependent Fourier transform infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Mahendia, Suman; Heena; Kandhol, Geeta; Deshpande, Uday P.; Kumar, Shyam

    2016-05-01

    In the present work, structural properties of reduced graphene oxide (RGO) synthesized using modified Hummer's method and its composites with Poly(vinyl alcohol) (PVA) fabricated using solution-cast method have been studied. The structural properties of prepared samples have been systematically studied through UV-Visible absorption, Raman, Fourier Transform Infrared (FTIR) and Differential Scanning Calorimeter (DSC) spectroscopy. Infrared spectroscopy indicates the grafting of PVA chains with graphene layer through the formation of H-bonding linkage in the composites. Temperature-dependent FTIR spectra of PVA-RGO composite films were recorded to obtain the glass transition temperature (Tg) and to study its molecular origin. From these spectra the values of Tg were obtained using two-dimensional (2D) mapping of the first derivative of the absorbance intensity with respect to temperature (dA/dT), over the space of wavenumber and temperature. The value of Tg obtained for pure PVA increases from 78 °C to 92 °C after loading 0.5 wt.% of RGO in PVA and can be attributed to the strong H-bonding interaction between polymer chains and grafted solid surface of RGO. These results are in good agreement with those obtained from DSC analysis. This clearly indicates that the thermal behavior of PVA gets modified with loading of RGO.

  18. Physicochemical and morphological properties of plasticized poly(vinyl alcohol)-agar biodegradable films.

    PubMed

    Madera-Santana, T J; Freile-Pelegrín, Y; Azamar-Barrios, J A

    2014-08-01

    The effects of the addition of glycerol (GLY) on the physicochemical and morphological properties of poly(vinyl alcohol) (PVA)-agar films were reported. PVA-agar films were prepared by solution cast method, and the addition of GLY in PVA-agar films altered the optical properties, resulting in a decrease in opacity values and in the color difference (ΔE) of the films. Structural characterization using Fourier transformation infrared (FTIR) spectroscopy and X-ray diffraction (XRD) indicated that the presence of GLY altered the intensity of the bands (from 1200 to 800cm(-1)) and crystallinity. The characterization of the thermal properties indicated that an increase in the agar content produces a decrease in the melting temperature and augments the heat of fusion. Similar tendencies were observed in plasticized films, but at different magnification. The formulation that demonstrated the lowest mechanical properties contained 25wt.% agar, whereas the formulation that contained 75wt.% agar demonstrated a significant improvement. The water vapor transmission rate (WVTR) and surface morphology analysis demonstrated that the structure of PVA-agar films is reorganized upon GLY addition. The physicochemical properties of PVA-agar films using GLY as a plasticizer provide information for the application of this formulation as packaging material for specific food applications. PMID:24875313

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

    PubMed Central

    2013-01-01

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

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

    PubMed

    Sun, Xiaoxia; Uyama, Hiroshi

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  2. 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. PMID:26411526

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

    NASA Astrophysics Data System (ADS)

    Sun, Xiaoxia; Uyama, Hiroshi

    2013-10-01

    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.

  4. Effects of hydrogen peroxide feeding strategies on the photochemical degradation of polyvinyl alcohol.

    PubMed

    Hamad, Dina; Dhib, Ramdhane; Mehrvar, Mehrab

    2016-11-01

    The performance of batch and fed-batch photoreactors with that of continuous photoreactor for the treatment of aqueous polyvinyl alcohol (PVA) solutions is compared. Hydrogen peroxide feeding strategies, residence time, and [H2O2]/[PVA] mass ratio are examined for their impacts on the molecular weight distribution (MWD) of PVA and the total organic carbon (TOC) removal. The results prove that a continuous addition of H2O2 during the degradation reaction ensures the utilization of the produced radicals to minimize the oxidant consumption and maximize the TOC removal and the PVA degradation in a short irradiation time. Also, the MWD of PVA is found to be bimodal and shifted towards lower molecular weights with small shoulder peak indicating a progressive disappearance of the higher molecular weight fractions that is in accordance with the random chains scission mechanism. Besides, the hydrogen peroxide feeding strategies are found to have a great effect on the reduction in H2O2 residuals in the effluent. PMID:27088453

  5. Hydrodynamics and oxygen mass transfer in a packed bed split-cylinder airlift reactor containing dilute alcoholic solutions

    NASA Astrophysics Data System (ADS)

    Keshavarz Moraveji, Mostafa; Ebrahimi Fakhari, Mona; Mohsenzadeh, Elmira; Davarnejad, Reza

    2013-01-01

    In this article, the influences of alcohols on the hydrodynamics and oxygen mass transfer characteristics in an airlift reactor equipped with packing were investigated. The hydrodynamic parameters and mass transfer coefficient in 1 % (v/v) aqueous solutions of four aliphatic alcohols were tested. It was concluded that alcohols addition increased gas holdup and gas-liquid mass transfer coefficient. The packing installation increased mass transfer coefficient, gas holdup and liquid circulation velocity, as well.

  6. Lithium Ion Polymer Electrolyte Based on Pva-Pan

    NASA Astrophysics Data System (ADS)

    Genova, F. Kingslin Mary; Selvasekarapandian, S.; Rajeswari, N.; Devi, S. Siva; Karthikeyan, S.; Raja, C. Sanjeevi

    2013-07-01

    The polymer blend electrolytes based on polyvinylalcohol(PVA) and polyacrylonitrile (PAN) doped with lithium per chlorate (LiClO4) have been prepared by solution casting technique using DMF as solvent. The complex formation between blend polymer and the salt has been confirmed by Fourier transform infrared spectroscopy. The amorphous nature of the blend polymer electrolyte has been confirmed by X-ray diffraction analysis. The ionic conductivity of the prepared blend polymer electrolyte has been found by ac impedence spectroscopic analysis. The highest ionic conductivity has been found to be 5.0 X10-4 S cm -1 at room temperature for 92.5 PVA: 7.5PAN: 20 molecular wt. % of LiClO4. The effect of salt concentration on the conductivity of the blend polymer electrolyte has been discussed.

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

    SciTech Connect

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

    1999-05-19

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

  8. Magnetic hydrogel beads based on PVA/sodium alginate/laponite RD and studying their BSA adsorption.

    PubMed

    Mahdavinia, Gholam Reza; Mousanezhad, Sedigheh; Hosseinzadeh, Hamed; Darvishi, Farshad; Sabzi, Mohammad

    2016-08-20

    In this study double physically crosslinked magnetic hydrogel beads were developed by a simple method including solution mixing of sodium alginate and poly(vinyl alcohol) (PVA) containing magnetic laponite RD (Rapid Dispersion). Sodium alginate and PVA were physically crosslinked by Ca(2+) and freezing-thawing cycles, respectively. Magnetic laponite RD nanoparticles were incorporated into the system to create magnetic response and strengthen the hydrogels. All hybrids double physically crosslinked hydrogel beads were stable under different pH values without any disintegration. Furthermore, adsorption of bovine serum albumin (BSA) on the hydrogel beads was investigated on the subject of pH, ion strength, initial BSA concentration, and temperature. Nanocomposite beads exhibited maximum adsorption capacity for BSA at pH=4.5. The experimental adsorption isotherm data were well followed Langmuir model and based on this model the maximum adsorption capacity was obtained 127.3mgg(-1) at 308K. Thermodynamic parameters revealed spontaneous and monolayer adsorption of BSA on magnetic nanocomposites beads. PMID:27178944

  9. PVA/CM-chitosan/honey hydrogels prepared by using the combined technique of irradiation followed by freeze-thawing

    NASA Astrophysics Data System (ADS)

    Afshari, M. J.; Sheikh, N.; Afarideh, H.

    2015-08-01

    Hydrogels with three components, poly(vinyl alcohol) (PVA), carboxymethylate chitosan (CM-chitosan) and honey have been prepared by using radiation method and radiation followed by freeze-thawing cycles technique (combinational method). The solid concentration of the polymer solution is 15 wt% and the ratios of PVA/CM-chitosan/honey are 10/1.5/3.5, 10/2/3, 10/3/2, and 10/3.5/1.5. The applied irradiation doses are 25, 30 and 40 kGy. Various tests have been done to evaluate the hydrogel properties to produce materials to be used as wound dressing. The results show that combinational method improves the mechanical strength of hydrogels while it has no significant effect on the water evaporation rate of gels. The combinational method decreases the swelling of hydrogels significantly, albeit this parameter is still acceptable for wound dressing. Microbiological analyses show that the hydrogel prepared by both methods can protect the wound from Escherichia coli bacterial infection. The wound healing test shows the good performance of the gels in mice.

  10. The role of MgBr2 to enhance the ionic conductivity of PVA/PEDOT:PSS polymer composite

    PubMed Central

    Sheha, Eslam M.; Nasr, Mona M.; El-Mansy, Mabrouk K.

    2014-01-01

    A solid polymer electrolyte system based on poly(vinyl alcohol) (PVA) and poly(3,4-Etylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) complexed with magnesium bromide (MgBr2) salt was prepared using solution cast technique. The ionic conductivity is observed to increase with increasing MgBr2 concentration. The maximum conductivity was found to be 9.89 × 10−6 S/cm for optimum polymer composite film (30 wt.% MgBr2) at room temperature. The increase in the conductivity is attributed to the increase in the number of ions as the salt concentration is increased. This has been proven by dielectric studies. The increase in conductivity is also attributable to the increase in the fraction of amorphous region in the electrolyte films as confirmed by their structural, thermal, electrical and optical properties. PMID:26199746

  11. Alcohol.

    ERIC Educational Resources Information Center

    Schibeci, Renato

    1996-01-01

    Describes the manufacturing of ethanol, the effects of ethanol on the body, the composition of alcoholic drinks, and some properties of ethanol. Presents some classroom experiments using ethanol. (JRH)

  12. Single-layer graphene-assembled 3D porous carbon composites with PVA and Fe₃O₄ nano-fillers: an interface-mediated superior dielectric and EMI shielding performance.

    PubMed

    Rao, B V Bhaskara; Yadav, Prasad; Aepuru, Radhamanohar; Panda, H S; Ogale, Satishchandra; Kale, S N

    2015-07-28

    In this study, a novel composite of Fe3O4 nanofiller-decorated single-layer graphene-assembled porous carbon (SLGAPC) with polyvinyl alcohol (PVA) having flexibility and a density of 0.75 g cm(-3) is explored for its dielectric and electromagnetic interference (EMI) response properties. The composite is prepared by the solution casting method and its constituents are optimized as 15 wt% SLGAPC and 20 wt% Fe3O4 through a novel solvent relaxation nuclear magnetic resonance experiment. The PVA-SLGAPC-Fe3O4 composite shows high dielectric permittivity in the range of 1 Hz-10 MHz, enhanced by a factor of 4 as compared to that of the PVA-SLGAPC composite, with a reduced loss by a factor of 2. The temperature dependent dielectric properties reveal the activation energy behaviour with reference to the glass transition temperature (80 °C) of PVA. The dielectric hysteresis with the temperature cycle reveals a remnant polarization. The enhanced dielectric properties are suggested to be the result of improvement in the localized polarization of the integrated interface system (Maxwell-Wagner-Sillars (MWS) polarization) formed by the uniform adsorption of Fe3O4 on the surface of SLGAPC conjugated with PVA. The EMI shielding property of the composite with a low thickness of 0.3 mm in the X-band (8.2-12.4 GHz) shows a very impressive shielding efficiency of ∼15 dB and a specific shielding effectiveness of 20 dB (g cm(-3))(-1), indicating the promising character of this material for flexible EMI shielding applications. PMID:26105548

  13. Using Micromechanical Resonators to Measure Rheological Properties and Alcohol Content of Model Solutions and Commercial Beverages

    PubMed Central

    Paxman, Rosemary; Stinson, Jake; Dejardin, Anna; McKendry, Rachel A.; Hoogenboom, Bart W.

    2012-01-01

    Micromechanic resonators provide a small-volume and potentially high-throughput method to determine rheological properties of fluids. Here we explore the accuracy in measuring mass density and viscosity of ethanol-water and glycerol-water model solutions, using a simple and easily implemented model to deduce the hydrodynamic effects on resonating cantilevers of various length-to-width aspect ratios. We next show that these measurements can be extended to determine the alcohol percentage of both model solutions and commercial beverages such as beer, wine and liquor. This demonstrates how micromechanical resonators can be used for quality control of every-day drinks. PMID:22778654

  14. 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. PMID:26700574

  15. Nonlinear optical properties of ZnO/poly (vinyl alcohol) nanocomposite films

    SciTech Connect

    Jeeju, P. P.; Jayalekshmi, S.; Chandrasekharan, K.

    2014-01-28

    Extensive studies have already been reported on the optical characteristics of ZnO/polymer nanocomposite films, using a variety of polymers including transparent polymers such as polystyrene, polymethyl methacrylate etc and many interesting results have been established regarding the non linear optical characteristics of these systems. Poly (vinyl alcohol)(PVA) is a water soluble polymer. Though the structural and optical studies of ZnO/PVA nanocomposite films have already been investigated, there are no detailed reports on the nonlinear optical characteristics of ZnO/PVA nanocomposite films, irrespective of the fact that these nanocomposite films can be synthesized using quite easy and cost effective methods. The present work is an attempt to study in detail the nonlinear optical behaviour of ZnO/PVA nanocomposite films using Z-scan technique. Highly transparent ZnO/PVA nanocomposite films were prepared from the ZnO incorporated PVA solution in water using spin coating technique. The ZnO nanoparticles were synthesized by the simple chemical route at room temperature. High-resolution transmission electron microscopy studies show that the ZnO nanoparticles are of size around 10 nm. The ZnO/PVA nanocomposite films were structurally characterized by X-ray diffraction technique, from which the presence of both PVA and ZnO in the nanocomposite was established. The optical absorptive nonlinearity in the nanocomposite films was investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption in ZnO with efficiency more than 50%. These films also show a self defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The present studies indicate that, highly transparent and homogeneous films of ZnO/PVA nanocomposite can be obtained on glass substrates using simple methods, in a highly cost effective way, since PVA is water soluble. These nanocomposite films offer

  16. Nonlinear optical properties of ZnO/poly (vinyl alcohol) nanocomposite films

    NASA Astrophysics Data System (ADS)

    Jeeju, P. P.; Jayalekshmi, S.; Chandrasekharan, K.

    2014-01-01

    Extensive studies have already been reported on the optical characteristics of ZnO/polymer nanocomposite films, using a variety of polymers including transparent polymers such as polystyrene, polymethyl methacrylate etc and many interesting results have been established regarding the non linear optical characteristics of these systems. Poly (vinyl alcohol)(PVA) is a water soluble polymer. Though the structural and optical studies of ZnO/PVA nanocomposite films have already been investigated, there are no detailed reports on the nonlinear optical characteristics of ZnO/PVA nanocomposite films, irrespective of the fact that these nanocomposite films can be synthesized using quite easy and cost effective methods. The present work is an attempt to study in detail the nonlinear optical behaviour of ZnO/PVA nanocomposite films using Z-scan technique. Highly transparent ZnO/PVA nanocomposite films were prepared from the ZnO incorporated PVA solution in water using spin coating technique. The ZnO nanoparticles were synthesized by the simple chemical route at room temperature. High-resolution transmission electron microscopy studies show that the ZnO nanoparticles are of size around 10 nm. The ZnO/PVA nanocomposite films were structurally characterized by X-ray diffraction technique, from which the presence of both PVA and ZnO in the nanocomposite was established. The optical absorptive nonlinearity in the nanocomposite films was investigated using open aperture Z-scan technique. The results indicate optical limiting type nonlinearity in the films due to two photon absorption in ZnO with efficiency more than 50%. These films also show a self defocusing type negative nonlinear refraction in closed aperture Z-scan experiment. The present studies indicate that, highly transparent and homogeneous films of ZnO/PVA nanocomposite can be obtained on glass substrates using simple methods, in a highly cost effective way, since PVA is water soluble. These nanocomposite films offer

  17. 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.

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

    PubMed

    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. PMID:21806259

  19. Crystal growth of ZnO bulk by CVT method using PVA

    NASA Astrophysics Data System (ADS)

    Udono, H.; Sumi, Y.; Yamada, S.; Kikuma, I.

    2008-04-01

    Seeded crystal growth of Zinc oxide (ZnO) by the closed ampoule chemical vapor transport (CVT) is carried out using polyvinyl alcohol (PVA) as a transport agent. Under the conditions of TS=1100 °C, Δ T=10 K and the amount of PVA=0.13-0.91 mg/cm 3, single-crystalline ZnO was grown continuously on the ZnO seed-crystal, of which the surface was (0 0 0 1) Zn-face. The grown crystals had well-marked growth facets belonged to {1 0 1¯0} and {1 0 1¯ 1} faces. The color of the crystals was changed from pale yellow to dark orange-red depending on the amount of PVA. Typical electron density and the Hall mobility of the crystals were 1×10 17 cm -3 and 2×10 2 cm 2/V s at 300 K, respectively.

  20. Solution behavior of metoclopramide in aqueous-alcoholic solutions at 30°C

    NASA Astrophysics Data System (ADS)

    Deosarkar, S. D.; Sawale, R. T.; Tawde, P. D.; Kalyankar, T. M.

    2016-07-01

    Densities (ρ) and refractive indices ( n D) of solutions of antiemetic drug metoclopramide (4-amino-5-chloro- N-(2-(diethylamino)ethyl)-2-methoxybenzamide hydrochloride hydrate) in methanolwater and ethanol-water mixtures of different compositions were measured at 30°C. Apparent molar volume (φv) of the drug was calculated from density data and partial molar volumes (φ v 0 ) were determined from Massons relation. Concentration dependence of nD has been studied to determine refractive indices of solution at infinite dilution ( n D 0 ). Results have been interpreted in terms of solute-solvent interactions.

  1. An evaluation of the biocompatibility properties of a salt-modified polyvinyl alcohol hydrogel for a knee meniscus application.

    PubMed

    Hayes, Jennifer C; Kennedy, James E

    2016-02-01

    The treatment of irreparable knee meniscus tears remains a major challenge for the orthopaedic community. The main purpose of this research was to analyse the biocompatibility properties of a salt-modified polyvinyl alcohol hydrogel, in order to assess its potential for use as an artificial meniscal implant. Aqueous polyvinyl alcohol was treated with a sodium sulphate solution to precipitate out the polyvinyl alcohol resulting in a pliable hydrogel. Cytotoxicological analysis indicates that PVA/sodium sulphate hydrogels display a non-toxic disposition and were found to be compatible with the L929 fibroblast cell line. PMID:26652445

  2. Low doping concentration studies of doped PVA-Coumarin nanocomposite films

    NASA Astrophysics Data System (ADS)

    Tripathi, J.; Tripathi, S.; Bisen, R.; Sharma, A.; Choudhary, A.; Shripathi, T.

    2016-05-01

    The observations of combination of Poly (vinyl) alcohol and Coumarin properties in nanocmposite films are reported. The X-ray diffraction measurements reveal nanocrystalline nature of PVA film, which remains nanocrystalline after doping Coumarin but along with PVA peaks, additional peak due to dopant crystallinity is seen. The absorption edge shows a double edge feature, where distinct bandgaps for PVA host and dopant Coumarin are obtained. However at a higher doping wt % of 1 and 2, the absorption is mainly dominated by Coumarin and single absorption edge is observed giving a bandgap equal to that of bulk Coumarin (3.3 eV). The composite formation affects the bonding of host drastically and is seen through the bond modification in FTIR spectra. The results suggest that doping below 2 wt% is advantageous as combination of PVA and Coumarin properties are obtained but at 2 wt %, the properties are dominated by mainly Coumarin and the signature of PVA from optical properties is completely lost.

  3. Synthesis and characterization of CdSe quantum dots dispersed in PVA matrix by chemical route

    NASA Astrophysics Data System (ADS)

    Khan, Zubair M. S. H.; Ganaie, Mohsin; Khan, Shamshad A.; Husain, M.; Zulfequar, M.

    2016-05-01

    CdSe quantum dots using polyvinyl alcohol as a capping agent have been synthesized via a simple heat induced thermolysis technique. The structural analysis of CdSe/PVA thin film was studied by X-ray diffraction, which confirms crystalline nature of the prepared film. The surface morphology and particle size of the prepared sample was studied by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). The SEM studies of CdSe/PVA thin film shows the average size of particles in the form of clusters of several quantum dots in the range of 10-20 nm. The morphology of CdSe/PVA thin film was further examined by TEM. The TEM image shows the fringes of tiny dots with average sizes of 4-7 nm. The optical properties of CdSe/PVA thin film were studied by UV-VIS absorption spectroscopy. The CdSe/PVA quantum dots follow the role of direct transition and the optical band gap is found to be 4.03 eV. From dc conductivity measurement, the observed value of activation energy was found to be 0.71 eV.

  4. Natural polysaccharides promote chondrocyte adhesion and proliferation on magnetic nanoparticle/PVA composite hydrogels.

    PubMed

    Hou, Ruixia; Nie, Lei; Du, Gaolai; Xiong, Xiaopeng; Fu, Jun

    2015-08-01

    This paper aims to investigate the synergistic effects of natural polysaccharides and inorganic nanoparticles on cell adhesion and growth on intrinsically cell non-adhesive polyvinyl alcohol (PVA) hydrogels. Previously, we have demonstrated that Fe2O3 and hydroxyapatite (nHAP) nanoparticles are effective in increasing osteoblast growth on PVA hydrogels. Herein, we blended hyaluronic acid (HA) and chondroitin sulfate (CS), two important components of cartilage extracellular matrix (ECM), with Fe2O3/nHAP/PVA hydrogels. The presence of these natural polyelectrolytes dramatically increased the pore size and the equilibrium swelling ratio (ESR) while maintaining excellent compressive strength of hydrogels. Chondrocytes were seeded and cultured on composite PVA hydrogels containing Fe2O3, nHAP and Fe2O3/nHAP hybrids and Fe2O3/nHAP with HA or CS. Confocal laser scanning microscopy (CLSM) and cell counting kit-8 (CCK-8) assay consistently confirmed that the addition of HA or CS promotes chondrocyte adhesion and growth on PVA and composite hydrogels. Particularly, the combination of HA and CS exhibited further promotion to cell adhesion and proliferation compared with any single polysaccharide. The results demonstrated that the magnetic composite nanoparticles and polysaccharides provided synergistic promotion to cell adhesion and growth. Such polysaccharide-augmented composite hydrogels may have potentials in biomedical applications. PMID:26037704

  5. Synthesis, characterization and antibacterial activity of biodegradable starch/PVA composite films reinforced with cellulosic fibre.

    PubMed

    Priya, Bhanu; Gupta, Vinod Kumar; Pathania, Deepak; Singha, Amar Singh

    2014-08-30

    Cellulosic fibres reinforced composite blend films of starch/poly(vinyl alcohol) (PVA) were prepared by using citric acid as plasticizer and glutaraldehyde as the cross-linker. The mechanical properties of cellulosic fibres reinforced composite blend were compared with starch/PVA crossed linked blend films. The increase in the tensile strength, elongation percentage, degree of swelling and biodegradability of blend films was evaluated as compared to starch/PVA crosslinked blend films. The value of different evaluated parameters such as citric acid, glutaraldehyde and reinforced fibre to starch/PVA (5:5) was found to be 25 wt.%, 0.100 wt.% and 20 wt.%, respectively. The blend films were characterized using Fourier transform-infrared spectrophotometry (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA/DTA/DTG). Scanning electron microscopy illustrated a good adhesion between starch/PVA blend and fibres. The blend films were also explored for antimicrobial activities against pathogenic bacteria like Staphylococcus aureus and Escherichia coli. The results confirmed that the blended films may be used as exceptional material for food packaging. PMID:24815414

  6. SHI irradiated PVA/Ag nanocomposites and possibility of UV blocking

    NASA Astrophysics Data System (ADS)

    Chahal, Rishi Pal; Mahendia, Suman; Tomar, A. K.; Kumar, Shyam

    2016-02-01

    The polyvinyl alcohol-silver (PVA/Ag) nanocomposites were prepared by in-situ chemical reduction method. The appearance of surface plasmon resonance (SPR) in the absorption spectrum of PVA/Ag nanocomposite films around 425 nm, confirmed the presence of Ag in the form of nanoparticles in host PVA matrix. In order to study the effect of swift heavy ions (SHI) irradiation on the optical and structural properties of these nanocomposites, the prepared films were irradiated to 90 MeV O6+ ion beam at two different fluence of 3 × 1010 and 1 × 1011 ions/cm2. The optical energy gap is found to be reduced from 4.57 eV (for PVA/Ag nanocomposite without irradiation) to 3.05 eV after irradiation at fluence of 1 × 1011 ions/cm2. The decline in the transmission of PVA/Ag nanocomposites in ultraviolet region, as a result of SHI irradiation, leads to their possible application in UV blocking devices. The induced structural re-arrangements, as a result of SHI irradiation, were revealed through the FTIR & Raman spectroscopy and found to be in strong association with the changes in optical behavior of these nanocomposites.

  7. X-ray irradiation-induced changes in (PVA-PEG-Ag) polymer nanocomposites films

    NASA Astrophysics Data System (ADS)

    Nouh, S. A.; Benthami, K.; Abutalib, M. M.

    2016-02-01

    The effects of X-ray irradiation on the structural, thermal and optical properties of polyvinyl alcohol-polyethylene glycol-silver (PVA-PEG-Ag) nanocomposites have been investigated. The samples of nanocomposites were prepared by adding Ag nanoparticles with 5 wt% to the (PVA-PEG) blend. The films of 0.05 mm thickness were prepared by the casting method. These films were irradiated with X-ray doses ranging from 20 to 200 kGy. The resultant effect of X-ray irradiation on the structural properties of PVA-PEG-Ag has been investigated using X-ray diffraction and Fourier transform infrared spectroscopy. Also, thermal property studies were carried out using thermogravimetric analysis. Further, the transmission of the PVA-PEG-Ag samples and any color changes were studied. Fourier transform infrared spectroscopy measurements showed that the crosslinking is the dominant mechanism at the dose range 50-200 kGy. This led to a more compact structure of PVA-PEG-Ag samples, which resulted in an improvement in its thermal stability with an increase in the activation energy of thermal decomposition. Moreover, the color intensity ΔE was greatly increased with an increase in the dose, and was accompanied by a significant increase in the yellow color component.

  8. Viscosities of cetylpyridinium bromide solutions (aqueous and aqueous KBr) in the presence of alcohols and amines

    SciTech Connect

    David, S.L.; Kumar, S.; Kabir-ud-Din

    1997-01-01

    Among the large number of additives, alcohols hold a special place, being by far the most common cosurfactants which are added to surfactant-oil combinations to generate microemulsions. Though the studies using amines as cosurfactant in microemulsions are few, it has been proved that they are also potential candidates for such formulations. The effect of organic additives (aliphatic/aromatic amines or alcohols) on the viscosities of aqueous and 0.1 M KBr solutions of 0.05 or 0.1 M cetylpyridinium bromide have been measured under Newtonian flow conditions. The viscosity changed dramatically in the presence of KBr. This is explained by the favorable conditions produced by the salt which assists the micellar growth by organic additives with a concomitant enhancement in viscosity. Reasons for the effectiveness of these additives are suggested. The causes of the viscosity decrease at higher concentrations of the additive are also explained.

  9. Thermodynamics of micelle formation in a water-alcohol solution of sodium tetradecyl sulfate

    NASA Astrophysics Data System (ADS)

    Shilova, S. V.; Tret'yakova, A. Ya.; Barabanov, V. P.

    2016-01-01

    The effects of addition of ethanol and propan-1-ol on sodium tetradecyl sulfate micelle formation in an aqueous solution are studied via microprobe fluorescence microscopy and conductometry. The critical micelle concentration, quantitative characteristics of micelles, and thermodynamic parameters of micelle formation are determined. Addition of 5-15 vol % of ethanol or 5-10 vol % of propan-1-ol is shown to result in a lower critical micelle concentration than in the aqueous solution, and in the formation of mixed spherical micelles whose sizes and aggregation numbers are less than those for the systems without alcohol. The contribution from the enthalpy factor to the free energy of sodium tetradecyl sulfate micelle formation is found to dominate in mixed solvents, in contrast to aqueous solutions.

  10. Photoluminescence study of PVP capped CdS nanoparticles embedded in PVA matrix

    SciTech Connect

    Pattabi, Manjunatha . E-mail: manjupattabi@yahoo.com; Saraswathi Amma, B.; Manzoor, K.

    2007-05-03

    Photoluminescence properties of polyvinyl pyrrolidone (PVP) capped cadmium sulphide (CdS) nanoparticles embedded in polyvinyl alcohol matrix (PVA) are reported. The PVP-CdS nanoparticles are prepared by non-aqueous method wherein cadmium nitrate is used as the cadmium source and hydrogen sulphide as the sulphur source. The synthesized nanoparticles are dispersed in polyvinyl alcohol (PVA) matrix and cast as self-standing flexible (PVP-CdS)-PVA films. The nanocomposites are characterized by optical absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. XRD and TEM studies show the formation of cubic CdS particles with average size {approx}3-5 nm. Thermal studies, carried out to observe the changes in PVA matrix due to the incorporation of PVP-CdS nanoparticles show strong interaction between the polymer matrix and nanoparticles. The photoluminescence emission spectra of the nanocomposites show two peaks, at 502 and 636 nm, which are attributed to the band edge and surface defects respectively, of CdS nanoparticles. Effective surface capping with optimum concentration of polyvinyl pyrrolidone leads to the quenching of surface defect-related emission.

  11. Effects of PVA, agar contents, and irradiation doses on properties of PVA/ws-chitosan/glycerol hydrogels made by γ-irradiation followed by freeze-thawing

    NASA Astrophysics Data System (ADS)

    Yang, Xiaomin; Zhu, Zhiyong; Liu, Qi; Chen, Xiliang; Ma, Mingwang

    2008-08-01

    Poly(vinyl alcohol) (PVA)/water soluble chitosan (ws-chitosan)/glycerol hydrogels were prepared by γ-irradiation and γ-irradiation followed by freeze-thawing, respectively. The effects of irradiation dose and the contents of PVA and agar on the swelling, rheological, and thermal properties of these hydrogels were investigated. The swelling capacity decreases while the mechanical strength increases with increasing PVA or agar content. Increasing the irradiation dose leads to an increase in chemical crosslinking density but a decrease in physical crosslinking density. Hydrogels made by irradiation followed by freeze-thawing own smaller swelling capacity but larger mechanical strength than those made by pure irradiation. The storage modulus of the former hydrogels decreases above 50 °C and above 70 °C it comes to the same value as that prepared by irradiation. The ordered association of PVA is influenced by both chemical and physical crosslinkings and by the presence of ws-chitosan and glycerol. These hydrogels are high sensitive to pH and ionic strength, indicating that they may be useful in stimuli-responsive drug release system.

  12. Poly(vinyl alcohol) gel sublayers for reverse osmosis membranes. I. Insolubilization by acid-catalyzed dehydration

    SciTech Connect

    Immelman, E.; Sanderson, R.D.; Jacobs, E.P.; Van Reenan, A.J. . Inst. of Polymer Science)

    1993-11-10

    Both flat-sheet and tubular composite reverse osmosis (RO) membranes were prepared by depositing aqueous solutions of poly(vinyl alcohol) (PVA) and a dehydration catalyst on asymmetric poly(arylether sulfone) (PES) substrate membranes. The PVA coatings were insolubilized by heat treatment to create stable hydrophilic gel-layer membranes. The influence of variables such as PVA concentration, catalyst concentration, curing time, and curing temperature was investigated. It was shown that a simple manipulation of one or two variables could lead to membranes with widely differing salt retention and water permeability characteristics. The insolubilized PVA coatings were intended to serve as hydrophilic gel sublayers on which ultra thin salt-retention barriers could ultimately be formed by interfacial polycondensation. For this purpose, high-flux gel layers were required, whereas salt-retention capabilities were not regarded as important. However, the promising salt retentions obtained as 2 MPa (up to 85% NaCl retention and 92% MgSO[sub 4] retention) showed that some of these PES-PVA composite membranes could function as medium-retention, medium-flux RO membranes, even in the absence of an interfacially formed salt-retention barrier.

  13. Preparation and properties of graphene oxide-regenerated cellulose/polyvinyl alcohol hydrogel with pH-sensitive behavior.

    PubMed

    Rui-Hong, Xie; Peng-Gang, Ren; Jian, Hui; Fang, Ren; Lian-Zhen, Ren; Zhen-Feng, Sun

    2016-03-15

    In this study, graphene oxide reinforced regenerated cellulose/polyvinyl alcohol (GO-RCE/PVA) ternary hydrogels were successfully prepared via a repeated freezing and thawing method in NaOH/urea aqueous solution. The effect of GO content on the mechanical properties, swelling behavior, water content of composite hydrogels was investigated. It was found that the mechanical properties of GO-RCE/PVA ternary hydrogels were largely enhanced relative to RCE/PVA hydrogels. With the addition of 1.0wt% GO, the tensile strength was increased by 40.4% from 0.52MPa to 0.73MPa, accompanied by the increase of the elongation at break (from 103% to 238%). Meanwhile, GO-RCE/PVA ternary hydrogels performed the excellent pH-sensitivity, and the higher pH leaded to higher swelling ratio. With 0.8wt% GO loading, the swelling ratio of GO-RCE/PVA ternary hydrogel was improved from 150% (pH=2) to 310% (pH=14). In addition, a slight increase in the water content of the ternary hydrogel was achieved with increasing concentrations of GO. It is believed that this novel ternary hydrogels is a promising material in the application of biomedical engineering and intelligent devices. PMID:26794756

  14. Enhancement in sensitivity of nitro blue tetrazolium polyvinyl alcohol film dosimeters by sodium formate and Triton X-100

    NASA Astrophysics Data System (ADS)

    Rabaeh, Khalid A.; Basfar, Ahmed A.; Moussa, Akram A.

    2012-04-01

    Nitro blue tetrazolium polyvinyl alcohol film dosimeters, NBT-PVA were prepared and evaluated based on radiation-induced reduction of NBT2+. NBT-PVA film dosimeters containing different concentrations of NBT dye from 1 to 5 mM were prepared in a solution of ethanol. The dosimeters were irradiated with ϒ-ray from 60Co source at doses up to 50 kGy. UV/vis spectrophotometer was used to investigate the optical density of un-irradiated and irradiated films in terms of absorbance at 529 nm. The absorbance increases with absorbed dose up to 50 kGy for NBT-PVA film dosimeters. The dose sensitivity of NBT-PVA film increases strongly with increase of concentrations of NBT dye. The effects of irradiation temperature, humidity, dose rate and the stability of the response of the films after irradiation were investigated. A considerable increase was observed in the dose response of NBT-PVA film by adding appropriate concentration of sodium formate and Triton X-100.

  15. FTIR studies of plasticized poly(vinyl alcohol)-chitosan blend doped with NH 4NO 3 polymer electrolyte membrane

    NASA Astrophysics Data System (ADS)

    Kadir, M. F. Z.; Aspanut, Z.; Majid, S. R.; Arof, A. K.

    2011-03-01

    Fourier transform infrared (FTIR) spectroscopy studies of poly(vinyl alcohol) (PVA), and chitosan polymer blend doped with ammonium nitrate (NH 4NO 3) salt and plasticized with ethylene carbonate (EC) have been performed with emphasis on the shift of the carboxamide, amine and hydroxyl bands. 1% acetic acid solution was used as the solvent. It is observed from the chitosan film spectrum that evidence of polymer-solvent interaction can be observed from the shifting of the carboxamide band at 1660 cm -1 and the amine band at 1591 cm -1 to 1650 and 1557 cm -1 respectively and the shift of the hydroxyl band from 3377 to 3354 cm -1. The hydroxyl band in the spectrum of PVA powder is observed at 3354 cm -1 and is observed at 3343 cm -1 in the spectrum of the PVA film. On addition of NH 4NO 3 up to 30 wt.%, the carboxamide, amine and hydroxyl bands shifted from 1650, 1557 and 3354 cm -1 to 1642, 1541 and 3348 cm -1 indicating that the chitosan has complexed with the salt. In the PVA-NH 4NO 3 spectrum, the hydroxyl band has shifted from 3343 to 3272 cm -1 on addition of salt from 10 to 30 wt.%. EC acts as a plasticizing agent since there is no shift in the bands as observed in the spectrum of PVA-chitosan-EC films. The mechanism of ion migration is proposed for the plasticized and unplasticized PVA-chitosan-NH 4NO 3 systems. In the spectrum of PVA-chitosan-NH 4NO 3-EC complex, the doublet C dbnd O stretching in EC is observed in the vicinity 1800 and 1700. This indicates that there is some interaction between the salt and EC.

  16. Investigation of polypyrrole/polyvinyl alcohol-titanium dioxide composite films for photo-catalytic applications

    NASA Astrophysics Data System (ADS)

    Cao, Shaoqiang; Zhang, Hongyang; Song, Yuanqing; Zhang, Jianling; Yang, Haigang; Jiang, Long; Dan, Yi

    2015-07-01

    Polypyrrole/polyvinyl alcohol-titanium dioxide (PPy/PVA-TiO2) composite films used as photo-catalysts were fabricated by combining TiO2 sol with PPy/PVA solution in which PPy was synthesized by in situ polymerization of pyrrole (Py) in polyvinyl alcohol (PVA) matrix and loaded on glass. The prepared photo-catalysts were investigated by X-ray diffraction (XRD), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectra and photoluminescence (PL). The results indicate that the composites have same crystal structure as the TiO2 and extend the optic absorption from UV region to visible light region. By detecting the variation ratio, detected by ultraviolet-vis spectroscopy, of model pollutant rhodamine B (RhB) solution in the presence of the composite films under both UV and visible light irradiation, the photo-catalytic performance of the composite films was investigated. The results show that the PPy/PVA-TiO2 composite films show better photo-catalytic properties than TiO2 film both under UV and visible light irradiation, and the photo-catalytic degradation of RhB follows the first-order kinetics. The effects of the composition of composite films and the concentration of RhB on the photo-catalytic performance, as well as the possible photo-catalytic mechanism, were also discussed. By photo-catalytic recycle experiments, the structure stability of the PPy/PVA-TiO2 composite film was investigated and the results show that the photo-catalytic activity under both UV and visible light irradiation have no significant decrease after four times of recycle experiments, suggesting that the photo-catalyst film is stable during the photo-catalytic process, which was also confirmed by the XRD pattern and FT-IR spectra of the composite film before and after photo-catalytic.

  17. UV irradiated PVA-Ag nanocomposites for optical applications

    NASA Astrophysics Data System (ADS)

    Chahal, Rishi Pal; Mahendia, Suman; Tomar, A. K.; Kumar, Shyam

    2015-07-01

    The present paper is focused on the in-situ prepared Poly (vinyl alcohol)-Silver (PVA-Ag) nanocomposites and tailoring their optical properties by means of UV irradiation in such a way that these can be used for anti-reflective coatings and bandpass filters. The reflectance from these irradiated nanocomposites has been found to decrease leading to the increase in refractive index (RI), with increasing UV exposure time, in the entire visible region. Decrease in optical energy gap of PVA film from 4.92 to 4.57 eV on doping with Ag nanoparticles has been observed which reduces further to 4.1 eV on exposure to UV radiations for 300 min. This decrease in optical energy gap can be correlated to the formation of charge transfer complexes within the base polymer network on embedding Ag nanoparticles, which further enhances with increasing exposure time. Such complexes may also be responsible for increased molecular density of the composite films which corresponds to decrease in reflectance corroborating the observed results.

  18. Preparation of a Cu(II)-PVA/PA6 Composite Nanofibrous Membrane for Enzyme Immobilization

    PubMed Central

    Feng, Quan; Tang, Bin; Wei, Qufu; Hou, Dayin; Bi, Songmei; Wei, Anfang

    2012-01-01

    PVA/PA6 composite nanofibers were formed by electrospinning. Cu(II)-PVA/PA6 metal chelated nanofibers, prepared by the reaction between PVA/PA6 composite nanofibers and Cu2+ solution, were used as the support for catalase immobilization. The result of the experiments showed that PVA/PA6 composite nanofibers had an excellent chelation capacity for Cu2+ ions, and the structures of nanofibers were stable during the reaction with Cu2+ solution. The adsorption of Cu(II) onto PVA/PA6 composite nanofibers was studied by the Langmuir isothermal adsorption model. The maximum amount of coordinated Cu(II) (qm) was 3.731 mmol/g (dry fiber), and the binding constant (Kl) was 0.0593 L/mmol. Kinetic parameters were analyzed for both immobilized and free catalases. The value of Vmax (3774 μmol/mg·min) for the immobilized catalases was smaller than that of the free catalases (4878 μmol/mg·min), while the Km for the immobilized catalases was larger. The immobilized catalases showed better resistance to pH and temperature than that of free form, and the storage stabilities, reusability of immobilized catalases were significantly improved. The half-lives of free and immobilized catalases were 8 days and 24 days, respectively. PMID:23202922

  19. Characterization and application of chondroitin sulfate/polyvinyl alcohol nanofibres prepared by electrospinning.

    PubMed

    Guo, Junxia; Zhou, Huitong; Akram, Muhammad Yasir; Mu, Xueyan; Nie, Jun; Ma, Guiping

    2016-06-01

    Composite nanofibres were prepared by electrospinning from a solution of chondroitin sulfate and polyvinyl alcohol. The chondroitin sulfate/polyvinyl alcohol (CS/PVA) mass ratios of 7/3 has a uniform and smooth morphology, and the average diameter of the nanofibres was 136nm. Combretastatin A-4 phosphate was loaded on the nanofibres and used as a model for testing drug release from the nanofibres crosslinked with glutaric dialdehyde. The morphology and structure of the nanofibres was determined using scanning electron microscopy. In order to assess their possible application to tissue engineering scaffolds, the toxicity and cytocompatibility of the nanofibres were tested by methylthiazolydiphenyl-tetrazolium bromide assay. PMID:27083365

  20. Novel Starch-PVA Polymer for Microparticle Preparation and Optimization Using Factorial Design Study

    PubMed Central

    Chattopadhyay, Helen; De, Amit Kumar; Datta, Sriparna

    2015-01-01

    The aim of our present work was to optimize the ratio of a very novel polymer, starch-polyvinyl alcohol (PVA), for controlled delivery of Ornidazole. Polymer-coated drug microparticles were prepared by emulsion method. Microscopic study, scanning electron microscopic study, and atomic force microscopic study revealed that the microparticles were within 10 micrometers of size with smooth spherical shape. The Fourier transform infrared spectroscopy showed absence of drug polymer interaction. A statistical 32 full factorial design was used to study the effect of different concentration of starch and PVA on the drug release profile. The three-dimensional plots gave us an idea about the contribution of each factor on the release kinetics. Hence this novel polymer of starch and polyvinyl alcohol can be utilized for control release of the drug from a targeted delivery device. PMID:27347511

  1. Biomaterial characteristics and application of silicone rubber and PVA hydrogels mimicked in organ groups for prostate brachytherapy.

    PubMed

    Li, Pan; Jiang, Shan; Yu, Yan; Yang, Jun; Yang, Zhiyong

    2015-09-01

    It is definite that transparent material with similar structural characteristics and mechanical properties to human tissue is favorable for experimental study of prostate brachytherapy. In this paper, a kind of transparent polyvinyl alcohol (PVA) hydrogel and silicone rubber are developed as suitable substitutions for human soft tissue. Segmentation and 3D reconstruction of medical image are performed to manufacture the mould of organ groups through rapid prototyping technology. Micro-structure observation, force test and CCD deformation test have been conducted to investigate the structure and mechanical properties of PVA hydrogel used in organ group mockup. Scanning electron microscope (SEM) image comparison results show that PVA hydrogel consisting of 3 g PVA, 17 g de-ionized water, 80 g dimethyl-sulfoxide (DMSO), 4 g NaCl, 1.5 g NaOH, 3 g epichlorohydrin (ECH) and 7 freeze/thaw cycles reveals similar micro-structure to human prostate tissue. Through the insertion force comparison between organ group mockup and clinical prostate brachytherapy, PVA hydrogel and silicone rubber are found to have the same mechanical properties as prostate tissue and muscle. CCD deformation test results show that insertion force suffers a sharp decrease and a relaxation of tissue deformation appears when needle punctures the capsule of prostate model. The results exhibit that organ group mockup consisting of PVA hydrogel, silicone rubber, membrane and agarose satisfies the needs of prostate brachytherapy simulation in general and can be used to mimic the soft tissues in pelvic structure. PMID:26042767

  2. Study the density, ultrasonic and compressibility of binary mixture of aqueous solution of isopropyl alcohol and mustard oil

    NASA Astrophysics Data System (ADS)

    Monupal, Suthar, B.

    2016-05-01

    The ultrasonic velocities, compressibility and bulk modulus of binary mixtures of aqueous solution of isopropyl alcohol with mustard oil have been measured at different concentrations at room temperature. The results are varied with the concentration in such a way i.e. ultrasonic velocity and Bulk Modulus is decreases with the increase in concentration and compressibility is increases with the increase in concentration of aqueous isopropyl alcohol. It is due to molecular interactions present in the mixtures.

  3. Electrical transport properties and current density - voltage characteristic of PVA-Ag nanocomposite film

    NASA Astrophysics Data System (ADS)

    Das, A. K.; Dutta, B.; Sinha, S.; Mukherjee, A.; Basu, S.; Meikap, A. K.

    2016-05-01

    Silver (Ag) nanoparticle and Polyvinyl alcohol (PVA) - Silver (Ag) composite have been prepared and its dielectric constant, ac conductivity, and current density-voltage characteristics have been studied, at and above room temperature. Here correlated barrier hopping found to be the dominant charge transport mechanism with maximum barrier height of 0.11 eV. The sample, under ±5 V applied voltage, show back to back Schottky diode behaviour.

  4. ZnS/PVA nanocomposites for nonlinear optical applications

    NASA Astrophysics Data System (ADS)

    Ozga, K.; Michel, J.; Nechyporuk, B. D.; Ebothé, J.; Kityk, I. V.; Albassam, A. A.; El-Naggar, A. M.; Fedorchuk, A. O.

    2016-07-01

    We have found a correlation between ZnS nanocomposite nonlinear optical features and technological processing using electrolytic method. In the earlier researches this factor was neglected. However, it may open a new stage for operation by photovoltaic features of the well known semiconductors within a wide range of magnitudes. The titled nanostructured zinc sulfide (ZnS) was synthesized by electrolytic method. The obtained ZnS nano-crystallites possessed nano-particles sizes varying within 1.6 nm…1.8 nm. The titled samples were analyzed by XRD, HR-TEM, STEM, and nonlinear optical methods such as photo-induced two-photon absorption (TPA) and second harmonic generation (SHG). For this reason the nano-powders were embedded into the photopolymer poly(vinyl) alcohol (PVA) matrices. Role of aggregation in the mentioned properties is discussed. Possible origin of the such correlations are discussed.

  5. Effect of PVA concentration on bond modifications in PVA-PMMA blend films

    NASA Astrophysics Data System (ADS)

    Tripathi, J.; Tripathi, S.; Sharma, A.; Bisen, R.; Shripathi, T.

    2016-05-01

    The optical properties of poly (methylmethacrylate) (PMMA) polymer are found to be modified when PVA molecules are added in the matrix of PMMA and vice versa making a blend. The concentrations studied were kept low to preserve the original properties of the host. It was seen that PMMA well protects its bonds and dominated the optical properties, while the properties of PVA are comparatively easier to modify when small amount of PMMA is inserted in PVA matrix. The results are interpreted in terms of bond modifications as seen from FTIR and absorption measurements and are useful in understanding the transparency and bandgap of the blend films.

  6. Frequency dependence of electron spin-lattice relaxation for semiquinones in alcohol solutions

    NASA Astrophysics Data System (ADS)

    Elajaili, Hanan B.; Biller, Joshua R.; Eaton, Sandra S.; Eaton, Gareth R.

    2014-10-01

    The spin-lattice relaxation rates at 293 K for three anionic semiquinones (2,5-di-t-butyl-1,4-benzosemiquinone, 2,6-di-t-butyl-1,4-benzosemiquinone, and 2,3,5,6-tetramethoxy-1,4-benzosemiquinone) were studied at up to 8 frequencies between 250 MHz and 34 GHz in ethanol or methanol solution containing high concentrations of OH-. The relaxation rates are about a factor of 2 faster at lower frequencies than at 9 or 34 GHz. However, in perdeuterated alcohols the relaxation rates exhibit little frequency dependence, which demonstrates that the dominant frequency-dependent contribution to relaxation is modulation of dipolar interactions with solvent nuclei. The relaxation rates were modeled as the sum of two frequency-independent contributions (spin rotation and a local mode) and two frequency-dependent contributions (modulation of dipolar interaction with solvent nuclei and a much smaller contribution from modulation of g anisotropy). The correlation time for modulation of the interaction with solvent nuclei is longer than the tumbling correlation time of the semiquinone and is consistent with hydrogen bonding of the alcohol to the oxygen atoms of the semiquinones.

  7. Dialkyl pyridinedicarboxylates` extraction ability toward copper(II) from chloride solutions and its modification with alcohols

    SciTech Connect

    Bogacki, M.B.; Jakubiak, A.; Szymanowski, J.; Cote, G.

    1997-03-01

    Dipentyl pyridinedicarboxylates (denoted hereafter as L) with different positions of the ester groups were synthesized and used for copper(II) extraction from chloride solutions containing up to 10 mol/L Cl{sup {minus}}. The effect of decanol addition on copper extraction was studied. A molecular modeling technique was used to estimate the structures of extractants, copper complexes, and associates with alcohol. It was found that the ability of pyridinecarboxylates to extract copper depends on the aqueous phase composition and the position of the ester groups in the pyridine ring. All the investigated compounds except dipentyl pyridine-2,6-dicarboxylate extract copper(II) by formation of CuCl{sub 2}L{sub 2} complexes. Dipentyl pyridine-2,6-dicarboxylate forms another type of complex, probably CuCl{sub 2}L. However, this compound is not suitable for copper extraction as its copper complex precipitates. Dipentyl pyridine-3,5-dicarboxylate was found to be the most suitable extractant among the various compounds listed. Finally it is shown that the possibilities to modify the extraction ability of pyridinecarboxylates with a hydrophobic alcohol such as decanol are relatively weak. Some enhancement was, however, observed when 20% of decanol was added to the organic phase containing dipentyl pyridine-3,5-dicarboxylate.

  8. Synthesis, characterisation and antibacterial activity of PVA/TEOS/Ag-Np hybrid thin films.

    PubMed

    Bryaskova, Rayna; Pencheva, Daniela; Kale, Girish M; Lad, Umesh; Kantardjiev, T

    2010-09-01

    Novel hybrid material thin films based on polyvinyl alcohol (PVA)/tetraethyl orthosilicate (TEOS) with embedded silver nanoparticles (AgNps) were synthesized using sol-gel method. Two different strategies for the synthesis of silver nanoparticles in PVA/TEOS matrix were applied based on reduction of the silver ions by thermal annealing of the films or by preliminary preparation of silver nanoparticles using PVA as a reducing agent. The successful incorporation of silver nanoparticles ranging from 5 to 7nm in PVA/TEOS matrix was confirmed by TEM and EDX analysis, UV-Vis spectroscopy and XRD analysis. The antibacterial activity of the synthesized hybrid materials against etalon strains of three different groups of bacteria -Staphylococcus aureus (gram-positive bacteria), Escherichia coli (gram-negative bacteria), Pseudomonas aeruginosa (non-ferment gram-negative bacteria) has been studied as they are commonly found in hospital environment. The hybrid materials showed a strong bactericidal effect against E. coli, S. aureus and P. aeruginosa and therefore have potential applications in biotechnology and biomedical science. PMID:20557895

  9. Pressure effect on water dynamics in tert-butyl alcohol/water solutions

    NASA Astrophysics Data System (ADS)

    Calandrini, Vania; Deriu, Antonio; Onori, Giuseppe; Paciaroni, Alessandro; Telling, Mark T. F.

    2006-09-01

    We report here a quasi-elastic neutron scattering (QENS) investigation of the effect of pressure on the diffusivity properties of water in a dilute aqueous solution of hydrophobic molecules (tert-butyl alcohol, TBA). The experiment was performed at fixed TBA concentration (0.02 molar fraction) by varying pressure from 1 to 2000 bar at two different temperatures (268 and 278 K). The quasi-elastic line-shapes have been analysed in terms of a model based on the memory function formalism. Our data indicate that, on increasing pressure up to 2000 bar, the diffusion coefficient of water in the TBA/water mixture exhibits a relative increase larger than that of pure water under the same thermodynamic conditions. The extent of this effect increases with decreasing temperature. The observed behaviour is described in terms of pressure-induced distortions of the H-bonded random network of liquid water.

  10. Dissolution and mechanical behaviors of recrystallized carbamazepine from alcohol solution in the presence of additives

    NASA Astrophysics Data System (ADS)

    Nokhodchi, A.; Bolourtchian, N.; Dinarvand, R.

    2005-02-01

    Carbamazepine (CBZ) crystals were grown from pure ethanol solutions containing various additives (PEG 4000, PVP K30 or Tween 80). Physical characteristics of the crystals were studied for the morphology of crystals using scanning electron microscope, for the identification of polymorphism by X-ray powder diffraction (XRPD) and FT-IR, and for thermodynamic properties using differential scanning calorimetery (DSC). The dissolution behaviour of various carbamazepine crystals was also studied by dissolution apparatus II at pH 7.4 containing 1% sodium lauryl sulphate (SLS). The scanning electron micrograph (SEM) studies showed that the presence of the additives in the solutions growth medium affected the morphology and size of carbamazepine crystals. SEMs of untreated and treated carbamazepine crystals obtained from alcohol containing PEG 4000, PVP K30 or Tween 80 showed that the crystal shape of untreated carbamazepine is flaky or thin plate-like, whereas the crystals obtained from alcohol containing no additive, PEG 4000, PVP K30 or Tween 80 are polyhedral prismatic, block-shaped, polyhedral or hexagonal, respectively. XRPD, FT-IR and DSC results showed that the untreated CBZ was form III and recrystallization of CBZ in the absence or presence of the additives did not cause any polymorphic changes. The results showed that the higher dissolution rate and compact strength were observed for the crystals obtained in the presence of PVP K30. The presence of the additives in crystallization medium alters crystal morphology of carbamazepine, but only the samples crystallized in the presence of PVP K30 showed an improvement in dissolution rate and tensile strength.

  11. Electric field-controlled benzoic acid and sulphanilamide delivery from poly(vinyl alcohol) hydrogel.

    PubMed

    Sittiwong, Jarinya; Niamlang, Sumonman; Paradee, Nophawan; Sirivat, Anuvat

    2012-12-01

    The controlled release of benzoic acid (3.31 Å) and sulphanilamide (3.47 Å) from poly(vinyl alcohol), PVA, hydrogels fabricated by solution casting at various cross-linking ratios, were investigated. The PVA hydrogels were characterized in terms of the degree of swelling, the molecular weight between cross-links, and the mesh size. The drug release experiment was carried out using a modified Franz diffusion cell, at a pH value of 5.5 and at temperature of 37°C. The amount of drug release and the diffusion coefficients of the drugs from the PVA hydrogels increased with decreasing cross-linking ratio, as a larger mesh size was obtained with lower cross-linking ratios. With the application of an electric field, the amount of drug release and the diffusion coefficient increased monotonically with increasing electric field strength, since the resultant electrostatic force drove the ionic drugs from the PVA matrix. The drug size, matrix pore size, electrode polarity, and applied electric field were shown to be influential controlling factors for the drug release rate. PMID:23065453

  12. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  14. PVA and PEG functionalised LSMO nanoparticles for magnetic fluid hyperthermia application

    SciTech Connect

    Jadhav, S.V.; Nikam, D.S.; Khot, V.M.; Mali, S.S.; Hong, C.K.; Pawar, S.H.

    2015-04-15

    La{sub 0.7}Sr{sub 0.3}MnO{sub 3} magnetic nanoparticles are synthesized by a solution combustion method and functionalised with polyvinyl alcohol and polyethylene glycol. The induction heating characteristics of coated magnetic nanoparticles (42 °C) were observed at a reasonably low concentration (5 mg/mL). Remarkably, coated magnetic nanoparticles exhibited a promisingly high specific absorption rate with varying magnetic field and constant frequency. The surface analysis is carried out by X-ray photoelectron spectroscopy. A reduction in the agglomeration of the particles was observed when the magnetic nanoparticles were functionalised with polyvinyl alcohol or polyethylene glycol and can be confirmed by transmission electron microscopy and dynamic light scattering studies. Vibrating sample magnetometer measurements indicate superparamagnetic behaviour at room temperature before and after coating. Colloidal stability revealed a considerably higher zeta potential value for coated system. In vitro cytotoxicity test of the magnetic nanoparticles indicates that coated nanoparticles have no significant effect on cell viability within the tested concentrations (1–5 mg mL{sup -1}) as compared to uncoated La{sub 0.7}Sr{sub 0.3}MnO{sub 3}. All these findings explore the potentiality of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} nanoparticles for magnetic fluid hyperthermia. - Highlights: • Surface functionalization of LSMO nanoparticles — first time with PVA • Surface functionalization of LSMO nanoparticles — first time with PEG • BSA protein — first time used as dispersion medium for stability of LSMO nanoparticles • The heating ability observed at low concentration • Improved efficiency of magnetic fluid hyperthermia treatment with surfactants.

  15. All-normal dispersion passively mode-locked Yb-doped fiber laser using MoS2-PVA saturable absorber

    NASA Astrophysics Data System (ADS)

    Sathiyan, S.; Velmurugan, V.; Senthilnathan, K.; Babu, P. Ramesh; Sivabalan, S.

    2016-05-01

    We demonstrate the generation of a dissipative soliton in an all-normal dispersion ytterbium (Yb)-doped fiber laser using few-layer molybdenum disulfide (MoS2) as a saturable absorber. The saturable absorber is prepared by mixing few-layer MoS2 solution with polyvinyl alcohol (PVA) to form a free-standing composite film. The modulation depth and saturation intensity of the MoS2-PVA film are 11% and 5.86 MW cm-2, respectively. By incorporating the MoS2 saturable absorber in the fiber laser cavity, the mode-locked pulses are generated with a pulse width of 1.55 ns and a 3 dB spectral bandwidth of 0.9 nm centered at 1037.5 nm. The fundamental repetition rate and the average power are measured as 15.43 MHz and 1.5 mW, respectively. These results reveal the feasibility of deploying liquid-phase exfoliated few-layer MoS2 nanosheets for dissipative soliton generation in the near-IR region.

  16. Highly sensitive optical sensor that detects Hg2+ and Cu2+ by immobilizing dicarboxylate 1,5-diphenyl-3-thiocarbazone on surface functionalized PVA microspheres

    NASA Astrophysics Data System (ADS)

    Bai, Xue; Gu, Haixin; Hua, Zulin; Dai, Zhangyan; Yang, Bei; Li, Yulong

    2015-11-01

    A novel optical sensor to detect Hg2+ and Cu2+ is prepared by immobilizing a synthesized dicarboxylate 1,5-diphenyl-3-thiocarbazone (DDT) group on functionalized polyvinyl alcohol (PVA) microspheres. This optical sensor is successfully fabricated by extensive characterization with Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Its colorimetric properties, selectivity, sensitivity, and reversibility are investigated as well. In this sensing system, DDT-PVA selectively recognized multiple heavy metal ions, as indicated by the changes in color from orange to scarlet for Hg2+ and from orange to gray for Cu2+. In particular, this optical sensor exhibits the most apparent color changes at pH levels of 12 and 2. Hence, Hg2+ and Cu2+ can be detected in aqueous solution at minimum detection limits of 0.053 and 0.132 μM, respectively, with a UV-vis spectrometer. Furthermore, the sensor can be regenerated by ethylene diamine tetraacetic acid and reused several times. Therefore, the optical sensor can detect Hg2+ because of its selectivity, sensitivity, and reversibility.

  17. Comparative study of the electrical and dielectric properties of PVA-PEG-Al 2O 3-MI (M=Na, K, Ag) complex polymer electrolytes

    NASA Astrophysics Data System (ADS)

    Prajapati, G. K.; Gupta, P. N.

    2011-08-01

    Plasticized nanocomposite polymer electrolytes (PNCPEs) based on poly(vinyl alcohol) (PVA)-MI (M=Na, K, Ag) dispersed with nanofillers Al 2O 3 and plasticized with poly(ethylene glycol) (PEG) have been prepared by solution cast technique. The structural properties of the samples have been characterized using various experimental techniques such as XRD, DSC, FTIR and B-G spectroscopy. The ionic conductivity and dielectric constant of the samples have been estimated using a LCZ meter in a wide temperature range, i.e. from 30 to 170 °C. It has been observed that the presence of water molecules in polymer electrolytes significantly affects the mobility of ionic species. The temperature dependent ionic conductivity shows the Arrhenius type behavior separated in three distinct regions. The ionic transference number for all PNCPE samples is found to be ≈1, which strongly suggests their ionic nature.

  18. Effect of interfibrillar PVA bridging on water stability and mechanical properties of TEMPO/NaClO2 oxidized cellulosic nanofibril films.

    PubMed

    Hakalahti, Minna; Salminen, Arto; Seppälä, Jukka; Tammelin, Tekla; Hänninen, Tuomas

    2015-08-01

    TEMPO/NaClO2 oxidized cellulosic nanofibrils (TCNF) were covalently bonded with poly(vinyl alcohol) (PVA) to render water stable films. Pure TCNF films and TCNF-PVA films in dry state showed similar humidity dependent behavior in the elastic region. However, in wet films PVA had a significant effect on stability and mechanical characteristics of the films. When soaked in water, pure TCNF films exhibited strong swelling behavior and poor wet strength, whereas covalently bridged TCNF-PVA composite films remained intact and could easily be handled even after 24h of soaking. Wet tensile strength of the films was considerably enhanced with only 10 wt% PVA addition. At 25% PVA concentration wet tensile strengths were decreased and films were more yielding. This behavior is attributed to the ability of PVA to reinforce and plasticize TCNF-based films. The developed approach is a simple and straightforward method to produce TCNF films that are stable in wet conditions. PMID:25933525

  19. Tuning Fe3O4 nanoparticle dispersion through pH in PVA/guar gum/electrospun membranes.

    PubMed

    Lubambo, A F; Ono, L; Drago, V; Mattoso, N; Varalda, J; Sierakowski, M-R; Sakakibara, C N; Freitas, R A; Saul, C K

    2015-12-10

    Polyvinyl Alcohol (PVA)/guar gum (GG) membranes with different loads of paramagnetic iron oxide Fe3O4 nanoparticles were successfully electrospun using both non-alkaline and alkaline stock solutions. The nanoparticle homogeneity distribution was clearly enhanced in fibers obtained from alkaline stock solutions. This is mainly due to the interaction between GG and the metallic ion, which also leads to further dispersion of remained uncoated nanoparticles in the mixture. It was also noticed that GG favors nanoparticle stability in the mixture and contributes to nanoparticle encapsulation. X-ray results showed that all membranes were semi-crystalline. FTIR-ATR spectra showed that Fe-O absorption band intensity improved with increasing nanoparticle load, reaching saturation at 3.5mg/ml Fe3O4 concentration under alkaline conditions. VSM analyses showed that the nanoparticles are paramagnetic and were successfully incorporated by the fibers. In vitro biocompatibility tests using L929 cells indicates adequate levels of cytotoxicity and cell adhesion/proliferation assays for both membranes obtained from non-alkaline and alkaline stock solutions. Therefore, they have potential for biomedical applications as biodegradable wound dressing. PMID:26428185

  20. Polyvinyl alcohol gelation: A structural locking-up agent and carbon source for Si/CNT/C composites as high energy lithium ion battery anode

    NASA Astrophysics Data System (ADS)

    Chen, Dingqiong; Liao, Wenjuan; Yang, Yang; Zhao, Jinbao

    2016-05-01

    A novel polyvinyl alcohol (PVA) hydrogel method is developed to synthesize Si/CNT/C composites. The Si nanoparticles and CNTs are 'position' locked up by PVA hydrogel in a simple aqueous solution process, and then the Si-CNT-PVA hydrogel has pyrolyzed to form Si/CNT/C composites. In this unique structured Si/CNT/C composites, the CNTs form a porous network acting both as conductive agent for electron transfer and buffer space to accommodate huge Si volume change during lithiation/delithiation process, while the coating layer of carbon carbonized from polyvinyl alcohol (PVA) hydrogel is conducive to stabilize the interweaved composite structure. The complex structures of Si/CNT/C composites and their electrochemical properties are presented in this paper. The Si/CNT/C composites exhibit an initial reversible capacity of nearly 800 mAhg-1, an excellent capacity retention of 97.1% after 100 cycles at the rate of 0.1 C, and high capacity retention even at high current rate.

  1. Polyvinyl alcohol gelation: A structural locking-up agent and carbon source for Si/CNT/C composites as high energy lithium ion battery anode

    NASA Astrophysics Data System (ADS)

    Chen, Dingqiong; Liao, Wenjuan; Yang, Yang; Zhao, Jinbao

    2016-05-01

    A novel polyvinyl alcohol (PVA) hydrogel method is developed to synthesize Si/CNT/C composites. The Si nanoparticles and CNTs are 'position' locked up by PVA hydrogel in a simple aqueous solution process, and then the Si-CNT-PVA hydrogel has pyrolyzed to form Si/CNT/C composites. In this unique structured Si/CNT/C composites, the CNTs form a porous network acting both as conductive agent for electron transfer and buffer space to accommodate huge Si volume change during lithiation/delithiation process, while the coating layer of carbon carbonized from polyvinyl alcohol (PVA) hydrogel is conducive to stabilize the interweaved composite structure. The complex structures of Si/CNT/C composites and their electrochemical properties are presented in this paper. The Si/CNT/C composites exhibit an initial reversible capacity of nearly 800 mAhg-1, an excellent capacity retention of 97.1% after 100 cycles at the rate of 0.1 C, and high capacity retention even at high current rate.

  2. Uniaxial Drawing of Graphene-PVA Nanocomposites: Improvement in Mechanical Characteristics via Strain-Induced Exfoliation of Graphene.

    PubMed

    Jan, Rahim; Habib, Amir; Akram, Muhammad Aftab; Zia, Tanveer-Ul-Haq; Khan, Ahmad Nawaz

    2016-12-01

    Polyvinyl alcohol (PVA)-stabilized graphene nanosheets (GNS) of lateral dimension (L) ~1 μm are obtained via liquid phase exfoliation technique to prepare its composites in the PVA matrix. These composites show low levels of reinforcements due to poor alignment of GNS within the matrix as predicted by the modified Halpin-Tsai model. Drawing these composites up to 200 % strain, a significant improvement in mechanical properties is observed. Maximum values for Young's modulus and strength are ~×4 and ~×2 higher respectively than that of neat PVA. Moreover, the rate of increase of the modulus with GNS volume fraction is up to 700 GPa, higher than the values predicted using the Halpin-Tsai theory. However, alignment along with strain-induced de-aggregation of GNS within composites accounts well for the obtained results as confirmed by X-ray diffraction (XRD) characterization. PMID:27558496

  3. Cellular response to poly(vinyl alcohol) nanofibers coated with biocompatible proteins and polysaccharides

    NASA Astrophysics Data System (ADS)

    Lee, So Young; Jang, Da Hyun; Kang, Yun Ok; Kim, O. Bok; Jeong, Lim; Kang, Hyun Ki; Lee, Seung Jin; Lee, Chong-Heon; Park, Won Ho; Min, Byung-Moo

    2012-07-01

    A PVA nanofibrous matrix was prepared by electrospinning an aqueous 10 wt% PVA solution. The mean diameter of the PVA nanofibers electrospun from the aqueous PVA solution was 240 nm. The water resistance of the as-spun PVA nanofibrous matrix was improved by physically crosslinking the PVA nanofibers by heat treatment at 150 °C for 10 min. In addition, the heat-treated PVA nanofibrous matrix was coated with biocompatible polysaccharides (chitosan (CHI) or hyaluronic acid (HA)) and proteins (collagen (COL) or silk fibroin (SF)) to construct biomimetic nanofibrous scaffolds. The coating of proteins or polysaccharides on the PVA nanofibrous matrix was confirmed by ATR-IR spectra, and the degree of coating was determined by elemental analysis based on nitrogen content. The coated PVA matrices exhibited less hydrophilicity, except for the HA coating, and better tensile properties than the pure PVA nanofibrous matrix. The increase in tensile properties was due to interfiber bonds formed by the coating. The effect of protein and polysaccharide coating on normal human keratinocytes (NHEKs) and fibroblasts (NHEFs) was examined by cytocompatibility assessment in vitro. Among the CHI-, COL-, HA- and SF-coated PVA matrices, the SF-coated PVA nanofibrous matrix was found to be the most promising scaffold for the attachment and spreading of NHEKs and NHEFs as compared to the pure PVA matrix. This approach to controlling the surface properties of nanofibrous structures with SF may be useful in the design and tailoring of novel matrices for skin regeneration.

  4. Mechanism for benzyl alcohol-induced aggregation of recombinant human interleukin-1 receptor antagonist in aqueous solution.

    PubMed

    Zhang, Ye; Roy, Shouvik; Jones, Latoya S; Krishnan, Sampathkumar; Kerwin, Bruce A; Chang, Byeong S; Manning, Mark C; Randolph, Theodore W; Carpenter, John F

    2004-12-01

    Benzyl alcohol, an antimicrobial preservative, accelerates aggregation and precipitation of recombinant human interleukin-1 receptor antagonist (rhIL-1ra) in aqueous solution. The loss of native monomer during incubation at 37 degrees C was determined by analysis of sample aliquots with size exclusion high performance liquid chromatography (SE-HPLC). Benzyl alcohol caused minor perturbation of the tertiary structure of the protein without changing its secondary structure, documenting that the preservative caused a minor shift in the protein molecular population toward partially unfolded species. Consistent with this conclusion, in the presence of benzyl alcohol the rate of H-D exchange was accelerated and the fluorescence of 1-anilinonaphthalene-8-sulfonic acid in the presence of rhIL1ra was increased. Benzyl alcohol did not alter the free energy of unfolding based on unfolding experiments in urea or guanidine HCl. With differential scanning calorimetry it was determined that benzyl alcohol reduced the apparent Tm of rhIL-1ra, but this effect occurred because the preservative lowered the temperature at which the protein aggregated during heating. Isothermal calorimetry documented that the interaction of benzyl alcohol with rhIL-1ra is relatively weak and hydrophobically driven. Thus, benzyl alcohol accelerates protein aggregation by binding to the protein and favoring an increase in the level of partially unfolded, aggregation-competent species. Sucrose partially inhibited benzyl alcohol-induced aggregation and tertiary structural change. Sucrose is preferentially excluded from the surface of the protein, favoring most compact native state species over expanded aggregation-prone forms. PMID:15514986

  5. Gel spinning of PVA composite fibers with high content of multi-walled carbon nanotubes and graphene oxide hybrids

    NASA Astrophysics Data System (ADS)

    Wei, Yizhe; Lai, Dengpan; Zou, Liming; Ling, Xinlong; Lu, Hongwei; Xu, Yongjing

    2015-07-01

    In this report, poly (vinyl alcohol) (PVA) composite fibers with high content of multi-walled carbon nanotubes and graphene oxide (MWCNTs-GO) hybrids were prepared by gel spinning, and were characterized by TGA, DSC, SEM, XL-2 yarn strength tester and electrical conductivity measurement. The total content of MWCNTs-GO hybrids in the PVA composite fibers, which is up to 25 wt%, was confirmed by TGA analysis. The DSC measurement shows that the melting and crystallization peaks decreased after the addition of nano-fillers. This is due to the reason that the motion of PVA chains is completely confined by strong hydrogen bonding interaction between PVA and nano-fillers. After the addtion of GO, the dispersibility of MWCNTs in composite fibers improved slightly. And the tensile strength and Young's modulus increased by 38% and 67%, respectively. This is caused by the increased hydrogen bonding interaction and synergistic effect through hybridization of MWCNTs and GO. More significantly, the electrical conductivity of PVA/MWCNTs/GO composite fibers enhanced by three orders of magnitude with the addition of GO.

  6. Modification of poly(vinylidene fluoride) ultrafiltration membranes with poly(vinyl alcohol) for fouling control in drinking water treatment.

    PubMed

    Du, Jennifer R; Peldszus, Sigrid; Huck, Peter M; Feng, Xianshe

    2009-10-01

    A commercial poly(vinylidene fluoride) flat sheet membrane was modified by surface coating with a dilute poly(vinyl alcohol) (PVA) aqueous solution followed by solid-vapor interfacial crosslinking. The resulting PVA layer increased membrane smoothness and hydrophilicity and resulted in comparable pure water permeation between the modified and unmodified membranes. Fouling tests using a 5 mg/L protein solution showed that a short period of coating and crosslinking improved the anti-fouling performance. After 18 h ultrafiltration of a surface water with a TOC of approximately 7 mg C/L, the flux of the modified membrane was twice as high as that of the unmodified membrane. The improved fouling resistance of the modified membrane was related to the membrane physiochemical properties, which were confirmed by pure water permeation, X-ray photoelectron spectroscopy, and contact angle, zeta potential and roughness measurements. PMID:19716151

  7. Cationic-modified PVA as a dry strength additive for rice straw fibers.

    PubMed

    Fatehi, P; Tutus, A; Xiao, H

    2009-01-01

    Extensive research has shown that non-wood fibers are able to be substituted for wood fibers. The major shortcoming of non-fibers is their high silica content that causes some operational problems in mills, and hence silica should be kept in pulps. By keeping silica in pulps, however, the mechanical properties of papers are reduced, and a dry strength additive may be required. In this study, cationic polyvinyl alcohols (C-PVA) with two different molecular weights were prepared, and employed as dry strength additives. The adsorption of polymers on rice straw fibers obtained via soda-air-anthraquinone (AQ) pulping under various conditions was investigated thoroughly. Convincing results demonstrated that high molecular weight polymers performed more efficiently on dry strength enhancements of papers, while they adsorbed less than lower molecular weight polymers on fibers. However, the stiffness of fibers was increased to a larger extent by applying a higher molecular weight C-PVA. PMID:18774707

  8. Interfacial bonding in a CdS/PVA nanocomposite: A Raman scattering study.

    PubMed

    Rudko, Galyna Yu; Kovalchuk, Andrii O; Fediv, Volodymyr I; Chen, Weimin M; Buyanova, Irina A

    2015-08-15

    Raman spectroscopy is employed to characterize the bonding between CdS nanoparticles (NPs) and a polyvinyl alcohol (PVA) as well as structural changes in the polymeric matrix caused by incorporation of NPs. It is shown that after the formation of CdS NPs the vibrations of carbonyl groups in acetate residuals of PVA and of C-O groups at the macromolecules ends disappear. Formation of NPs also leads to an increased degree of hydrogen bonding and crystallinity of the hybrid material as compared with the unloaded polymer. The observed changes are ascribed to the formation of coordinative bonds and hydrogen between the CdS nanoparticles and polymeric macromolecules. The scheme of this interfacial bonding is also proposed. PMID:25910224

  9. Ternary PVA nanocomposites containing cellulose nanocrystals from different sources and silver particles: part II.

    PubMed

    Fortunati, E; Luzi, F; Puglia, D; Terenzi, A; Vercellino, M; Visai, L; Santulli, C; Torre, L; Kenny, J M

    2013-09-12

    Cellulose nanocrystals (CNC) extracted from three different sources, namely flax, phormium, and commercial microcrystalline cellulose (MCC) have been used in a polyvinyl alcohol (PVA) matrix to produce anti-bacterial films using two different amounts of silver nanoparticles (0.1 wt% and 0.5 wt%). In general, CNC confer an effect of reinforcement to PVA film, the best values of stiffness being offered by composites produced using phormium fibres, whilst for strength those produced using flax are slightly superior. This was obtained without inducing any particular modification in transition temperatures and in the thermal degradation patterns. As regards antibacterial properties, systems with CNC from flax proved slightly better than those with CNC from phormium and substantially better than those including commercial MCC. Dynamic mechanical thermal analysis (DMTA) has only been performed on the ternary composite containing 0.1 wt% Ag, which yielded higher values of Young's modulus, and as a whole confirmed the above results. PMID:23911522

  10. Synthesis, characterization and application of biodegradable crosslinked carboxymethyl chitosan/poly(vinyl alcohol) clay nanocomposites.

    PubMed

    Sabaa, Magdy W; Abdallah, Heba M; Mohamed, Nadia A; Mohamed, Riham R

    2015-11-01

    Crosslinked poly(vinyl alcohol) (PVA)/carboxymethyl chitosan (CMCh) nanocomposites were synthesized using terephthaloyl diisothiocyanate crosslinker, in the presence of montmorillonite (MMT), in different ratios of the two matrices. Characterization of nanocomposites was performed using different analyses. Swelling behavior was studied in different buffered solutions. It was found that formation of crosslinked CMCh/PVA hydrogels increased the swellability. Metal ion adsorption has also been investigated. The results indicated that crosslinked CMCh adsorbs various metal ions much more than non crosslinked CMCh. Antimicrobial activity was examined against Gram positive bacteria, against Gram negative bacteria, and also against fungi. Results indicated that most of these nanocomposites exhibited good antimicrobial potency. Degradation study was carried out in Simulated Body Fluid (SBF) for different time periods in order to find out degradation index (Di). Results showed that weight loss of most of the nanocomposites increased as a function of incubation time. PMID:26249602

  11. Down shifting in poly(vinyl alcohol) gels doped with terbium complex.

    PubMed

    Di Lorenzo, Maria Laura; Cocca, Mariacristina; Avella, Maurizio; Gentile, Gennaro; Gutierrez, David; Della Pirriera, Monica; Torralba-Calleja, Elena; Kennedy, Manus; Ahmed, Hind; Doran, John

    2016-09-01

    Novel poly(vinyl alcohol) (PVA) based soft gels with luminescent properties are detailed in this contribution. Lanthanide complex of terbium ions with anthranilic acid, Tb(ant)3·2H2O, was synthesized and incorporated into a DMSO/water solution, followed by addition of PVA, to attain soft gels at room temperature. Morphological and thermal analyses revealed homogeneous distribution of Tb(ant)3·2H2O into the PVOH/DMSO/water gel, and that incorporation of the terbium complex does not alter the thermal properties of the gels. The gels are transparent and luminescent, as they exhibit Large Stokes shift down shifting (LSS DS) up to 400nm, with very high emission quantum yield, that was found to be function of Tb complex concentration. PMID:27236842

  12. Fabrication of Poly (methyl methacrylate) and Poly(vinyl alcohol) Thin Film Capacitors on Flexible Substrates

    NASA Astrophysics Data System (ADS)

    Salim, Bindu; Meenaa Pria KNJ, Jaisree; Alagappan, M.; Kandaswamy, A.

    2015-11-01

    Flexible electronics is becoming more popular with introduction of more and more organic conducting materials and processes for making thin films. The use of polymers as gate dielectric has over ruled the usage of conventional inorganic oxides in Organic Thin Film Transistors (OTFTs) on account of its solution process ability and ease of making highly insulating thin film. In this work Capacitance is fabricated with polymeric dielectrics namely poly (methyl methacrylate) - PMMA and poly (vinyl alcohol) - PVA. The electrodes used for these capacitors are Indium Tin Oxide (ITO) and Aluminium. Capacitance value of 9.5nF/cm2 and 33.12nF/cm2 is achieved for thickness of 510 nm of PMMA and 80 nm of PVA respectively. This study on capacitance can be used for assessing the suitability of these polymers as gate insulators in OTFTs.

  13. 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.

  14. Aggregation in dilute aqueous tert-butyl alcohol solutions: Insights from large-scale simulations

    NASA Astrophysics Data System (ADS)

    Gupta, Rini; Patey, G. N.

    2012-07-01

    Molecular dynamics simulations employing up to 64 000 particles are used to investigate aggregation and microheterogeneity in aqueous tert-butyl alcohol (TBA) solutions for TBA mole fractions Xt ⩽ 0.1. Four different force fields are considered. It is shown that the results obtained can be strongly dependent on the particular force field employed, and can be significantly influenced by system size. Two of the force fields considered show TBA aggregation in the concentration range Xt ≈ 0.03 - 0.06. For these models, systems of 64 000 particles are minimally sufficient to accommodate the TBA aggregates. The structures resulting from TBA aggregation do not have a well-defined size and shape, as one might find in micellar systems, but are better described as TBA-rich and water-rich regions. All pair correlation functions exhibit long-range oscillatory behavior with wavelengths that are much larger than molecular length scales. The oscillations are not strongly damped and the correlations can easily exceed the size of the simulation cell, even for the low TBA concentrations considered here. We note that these long-range correlations pose a serious problem if one wishes to obtain certain physical properties such as Kirkwood-Buff integrals from simulation results. In contrast, two other force fields that we consider show little sign of aggregation for Xt ≲ 0.08. In our 64 000 particle simulations all four models considered show demixing-like behavior for Xt ≳ 0.1, although such behavior is not evident in smaller systems of 2000 particles. The meaning of the demixing-like behavior is unclear. Since real TBA-water solutions do not demix, it might be an indication that all four models we consider poorly represent the real system. Alternatively, it might be an artifact of finite system size. Possibly, the apparent demixing indicates that for Xt ≳ 0.1, the stable TBA aggregates are simply too large to fit into the simulation cell. Our results provide a view of the

  15. 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.

  16. Biodegradation of crystal violet using Burkholderia vietnamiensis C09V immobilized on PVA-sodium alginate-kaolin gel beads.

    PubMed

    Cheng, Ying; Lin, HongYan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravi

    2012-09-01

    The strain, Burkholderia vietnamiensis C09V was immobilized on PVA-alginate-kaolin gel beads as a biomaterial to improve the degradation of crystal violet from aqueous solution. The results show that 98.6% (30 mg L(-1)) crystal violet was removed from aqueous solution using immobilized cells on PVA-alginate-kaolin gel beads, while 94.0% crystal violet was removed by free cells after degradation at the pH 5 and 30°C for 30 h. Kinetics studies show that the pseudo-second-order kinetics well described the adsorption of crystal violet on the PVA-alginate-kaolin beads. Biodegradation of crystal violet on immobilized cells was fitted well by first-order reaction kinetics, indicating that CV was adsorbed onto kaolin and followed their degradation by immobilized cells onto the the PVA-alginate-kaolin beads. Characterization with SEM shows that cells attached well to the surface of PVA-alginate-kaolin beads, leading to improved crystal violet transfer from aqueous solution to immobilized cells. In addition, UV-vis show that the absorption peak at 588 nm was reduced by the degraded N-bond linkages, as well as the formation of degrading products were observed by Fourier transform infrared (FTIR). These results suggest that crystal violet was biodegraded to N,N-dimethylaminophenol and Michler's Ketone prior to these intermediates being further degraded. PMID:22789742

  17. Smart carbon nanotube/fiber and PVA fiber-reinforced composites for stress sensing and chloride ion detection

    NASA Astrophysics Data System (ADS)

    Hoheneder, Joshua

    Fiber reinforced composites (FRC) with polyvinyl alcohol (PVA) fibers and carbon nanofibers (CNF) had an excellent flexural strength in excess of 18.5 MPa compared to reference samples of 15.8 MPa. It was found that the developed, depending on applied stress and exposure to chloride solutions, composites exhibit some electrical conductivity, from 4.20×10 -4 (Ω-1m-1 to 4.13×10 -4 Ω-1m-1. These dependences can be characterized by piezioresistive and chemoresistive coefficients demonstrating that the material possesses self-sensing capabilities. The sensitivity to stain and chloride solutions can be enhanced by incorporating small amounts of carbon nanofibers (CNF) or carbon nanotube (CNT) into composite structure. Conducted research has demonstrated a strong dependency of electrical properties of composite on crack formation in moist environments. The developed procedure is scalable for industrial application in concrete structures that require nondestructive stress monitoring, integrity under high service loads and stability in harsh environments.

  18. Pristine graphene dispersions and solution-cast composites

    NASA Astrophysics Data System (ADS)

    Das, Sriya; Irin, Fahmida; Wajid, Ahmed; Cortinas, Abel; Green, Micah

    2012-02-01

    Graphene holds potential as strong, conductive fillers in polymer nanocomposites; however, difficulties in dispersion quality and interfacial strength between filler and matrix have been a persistent problem for graphene-based nanocomposites, particularly for pristine, unfunctionalized graphene. We utilize a triphenylene based molecule (C10) to stabilize pristine graphene in water with a high graphene/stabilizer ratio. C10 molecules pi-pi stack with the graphene surface and prevent reaggregation. This dispersion can be reversibly destabilized based on pH and is stable against heat and lyophilization. Solution cast poly (vinyl alcohol) (PVA) composites prepared from these dispersions have enhanced mechanical and electrical properties (percolation threshold: 0.26 vol % graphene). Also, for the first time, pristine graphene/PVA dispersions are electrospun to form graphene/polymer composite nanofibers.

  19. Microstructure Changes of Copper Nano Particles via Polymer Solution and Reduction Firing Processes.

    PubMed

    Han, Young-Min; Jung, Choong-Hwan; Lee, Sang-Jin

    2016-02-01

    Cu nano particles were fabricated at a very low temperature via polymer solution and reduction firing processes using a polyvinyl alcohol (PVA) and Ar-4%H2 gas mixture. In the process, copper nitrate and 5 wt% PVA solution were dissolved in D.I. water and the organic-inorganic precursor sols were dried to porous gels. The precursor gels were calcined in an air atmosphere, and then refired at 250 degrees C-300 degrees C under an Ar-4%H2 atmosphere for the reduction of CuO. The morphology of precursor gels and CuO and Cu powders was strongly dependent on the PVA content, and the as- calcined CuO readily deoxidized to Cu with minimal residual carbon. The polymer also contributed to an atomic-scale copper cation distribution, which resulted in nano-sized CuO and Cu powders. The Cu powder synthesized with PVA content in a 4:1 ratio showed a crystallite size of about 20 nm or less. In this paper, the microstructure changes of Cu nano particles at each set of processing conditions were examined by SEM and TEM observations. PMID:27433717

  20. Fabrication of porous chitosan/poly(vinyl alcohol) reinforced single-walled carbon nanotube nanocomposites for neural tissue engineering.

    PubMed

    Shokrgozar, Mohammad Ali; Mottaghitalab, Fatemeh; Mottaghitalab, Vahid; Farokhi, Mehdi

    2011-04-01

    With the ability to form a nano-sized fibrous structure with large pore sizes mimicking the extracellular matrix (ECM), electrospinning was used to fabricate chitosan/poly(vinyl alcohol) nanofibers reinforced by single-walled carbon nanotube (SWNT-CS/PVA) for potential use in neural tissue engineering. Moreover, ultrasonication was performed to fabricate highly dispersed SWNT/CS solution with 7%, 12%, and 17% SWNT content prior to electrospinning process. In the present study, a number of properties of CS/PVA reinforced SWNTs nanocomposites were evaluated. The in vitro biocompatibility of the electrospun fiber mats was also assessed using human brain-derived cells and U373 cell lines. The results have shown that SWNTs as reinforcing phase can augment the morphology, porosity, and structural properties of CS/PVA nanofiber composites and thus benefit the proliferation rate of both cell types. In addition, the cells exhibit their normal morphology while integrating with surrounding fibers. The results confirmed the potential of SWNT-CS/PVA nanocomposites as scaffold for neural tissue engineering. PMID:21702365

  1. In vitro-in vivo sequence studies as a method of selecting the most efficacious alcohol-based solution for hygienic hand disinfection.

    PubMed

    Herruzo, R; Vizcaino, M J; Herruzo, I

    2010-05-01

    The use of alcohol-based hand rubs serves to reduce hospital-acquired infections. Many products of this type are now on offer and it is essential to know how to rank their efficacy. A sequence of tests is proposed here to compare any given new alcohol-based solution against the reference solution (60% 2-isopropyl-alcohol) with 30 s of contact time: (i) in vitro (with pig skin as carrier) testing of >30 species of microorganism; (ii) in vitro assessment of residual efficacy (after 30 min of drying); (iii) in vivo study of transient microbiota (modification of the EN 1500 standard procedure) using four ATCC strains; (iv) in vivo study of resident hand microbiota. After performing the in vitro evaluation of seven alcohol-based hand rubs, the two most efficacious (chlorhexidine-quac-alcohol and mecetronium- alcohol) were chosen and studied, comparatively with the reference solution (60% isopropyl alcohol), in vitro (for chemical sustainability on the skin) and in vivo (against transient and resident microbiota). Chlorhexidine-quac-alcohol proved to be significantly superior to mecetronium-alcohol or the reference solution in all tests, except against resident microbiota for which the improvement was not statistically significant. PMID:19624506

  2. Linear and nonlinear optical study of pure PVA and CdSe doped PVA nanocomposite

    NASA Astrophysics Data System (ADS)

    Tyagi, Chetna; Sharma, Ambika

    2016-05-01

    This research work reports the synthesis and optical properties of CdSe/PVA polymer nanocomposite (PNC's) prepared by wet chemical co-precipitation method. The transmission spectra obtained from UV-Vis-NIR spectrophotometer has been investigated to determine the optical properties of PNC's. Absorption spectra give the information about energy band gap (Eg) and type of transition. Refractive index (n), extinction coefficient (k) was calculated using well known Swanepoel method. Wemple-Di Domenico model (WDD) has been used to calculate dispersion energy (Ed) and oscillator energy (E0). Boling formula is used to calculate nonlinear refractive index (n2) of CdSe/PVA nanocomposite.

  3. Preparation and photoluminescence of monolithic silica glass doped with Tb3+ ions using SiO2-PVA nanocomposite

    NASA Astrophysics Data System (ADS)

    Ikeda, Hiroshi; Murata, Takahiro; Fujino, Shigeru

    2014-05-01

    The monolithic silica glass doped with Tb3+ ions was fabricated using the SiO2-PVA nanocomposite as the glass precursor. In order to dope Tb3+ ions in the monolithic silica glass, the mesoporous SiO2-PVA nanocomposite was immersed in the Tb3+ ions contained solution and subsequently sintered at 1100 °C in air. Consequently the monolithic transparent silica glass was obtained, exhibiting green fluorescence attributed to 5D4 → 7F5 main transitions under UV excitation. The Tb concentration in the sintered glass could be controlled by immersion time of the nanocomposite in the solution.

  4. ZnO-PVA nanocomposite films for low threshold optical limiting applications

    NASA Astrophysics Data System (ADS)

    Viswanath, Varsha; Beenakumari, C.; Muneera, C. I.

    2014-10-01

    Zinc oxide-PVA nanocomposite films were fabricated adopting a simple method based on solution-casting, incorporating small weight percentages (<1.2 wt%) of ZnO in PVA (˜0.625×10-3M to 7×10-3M), and their structure, morphology, linear and low threshold nonlinear optical properties were investigated. The films were characterized as nanostructured ZnO encapsulated between the molecules/chains of the semicrystalline host polymer PVA. The samples exhibited low threshold nonlinear absorption and negative nonlinear refraction, as studied using the Z-scan technique. A switchover from SA to RSA was observed as the concentration of ZnO was increased. The optical limiting of 632.8 nm CW laser light displayed by these nanocomposite films is also demonstrated. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |χ(3)|, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. The results show that the ZnO-PVA nanocomposite films have great potential applications in future optical and photonic devices.

  5. ZnO-PVA nanocomposite films for low threshold optical limiting applications

    SciTech Connect

    Viswanath, Varsha; Beenakumari, C.; Muneera, C. I.

    2014-10-15

    Zinc oxide-PVA nanocomposite films were fabricated adopting a simple method based on solution-casting, incorporating small weight percentages (<1.2 wt%) of ZnO in PVA (∼0.625×10{sup −3}M to 7×10{sup −3}M), and their structure, morphology, linear and low threshold nonlinear optical properties were investigated. The films were characterized as nanostructured ZnO encapsulated between the molecules/chains of the semicrystalline host polymer PVA. The samples exhibited low threshold nonlinear absorption and negative nonlinear refraction, as studied using the Z-scan technique. A switchover from SA to RSA was observed as the concentration of ZnO was increased. The optical limiting of 632.8 nm CW laser light displayed by these nanocomposite films is also demonstrated. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |χ{sup (3)}|, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. The results show that the ZnO-PVA nanocomposite films have great potential applications in future optical and photonic devices.

  6. Poly(vinyl alcohol) hydrogel coatings with tunable surface exposure of hydroxyapatite

    PubMed Central

    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. PMID:25482413

  7. 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. PMID:25482413

  8. Amniotic membrane immobilized poly(vinyl alcohol) hybrid polymer as an artificial cornea scaffold that supports a stratified and differentiated corneal epithelium.

    PubMed

    Uchino, Yuichi; Shimmura, Shigeto; Miyashita, Hideyuki; Taguchi, Tetsushi; Kobayashi, Hisatoshi; Shimazaki, Jun; Tanaka, Junzo; Tsubota, Kazuo

    2007-04-01

    Poly(vinyl alcohol) (PVA) is a biocompatible, transparent hydrogel with physical strength that makes it promising as a material for an artificial cornea. In our previous study, type I collagen was immobilized onto PVA (PVA-COL) as a possible artificial cornea scaffold that can sustain a functional corneal epithelium. The cellular adhesiveness of PVA in vitro was improved by collagen immobilization; however, stable epithelialization was not achieved in vivo. To improve epithelialization in vivo, we created an amniotic membrane (AM)-immobilized polyvinyl alcohol hydrogel (PVA-AM) for use as an artificial cornea material. AM was attached to PVA-COL using a tissue adhesive consisting of collagen and citric acid derivative (CAD) as a crosslinker. Rabbit corneal epithelial cells were air-lift cultured with 3T3 feeder fibroblasts to form a stratified epithelial layer on PVA-AM. The rabbit corneal epithelial cells formed 3-5 layers of keratin-3-positive epithelium on PVA-AM. Occludin-positive cells were observed lining the superficial epithelium, the gap-junctional protein connexin43-positive cells was localized to the cell membrane of the basal epithelium, while both collagen IV were observed in the basement membrane. Epithelialization over implanted PVA-AM was complete within 2 weeks, with little inflammation or opacification of the hydrogel. Corneal epithelialization on PVA-AM in rabbit corneas improved over PVA-COL, suggesting the possibility of using PVA-AM as a biocompatible hybrid material for keratoprosthesis. PMID:16924609

  9. Experimental Evidence of the Effect of Evaporation-Condensation on Thermal Marangoni Flows in Aqueous Fatty Alcohol Solutions.

    PubMed

    Azouni; Pétré

    1998-10-01

    The static surface tension (final sigmae) of aqueous solutions of a fatty alcohol versus temperature exhibits a minimum. Thus, a temperature gradient which is created at the free surface of such a solution at temperatures higher than that of the minimum (final sigmae) should induce a surface flow from the cold area to the hot one. This was indeed observed even at temperatures much lower than that of the minimum. A possible explanation is the evaporation of alcohol at the hot area where the surface tension increases, and its condensation on the cold area where the surface tension decreases, the alcohol being tranported by the gas phase. The thickness of the gas phase over the liquid could play a role in the observed flows. A device was built in which the thickness of the gas phase could be adjusted. Experiments performed with a 6.2 x 10(-3) m solution of n-heptanol indicate a lowering of the surface velocity where the thickness of the gas phase is reduced. Copyright 1998 Academic Press. PMID:9761660

  10. Impact of tert-butyl alcohol on crystallization kinetics of gemcitabine hydrochloride in frozen aqueous solutions.

    PubMed

    Munjal, Bhushan; Bansal, Arvind K

    2015-01-01

    The effect of tert-butyl alcohol (TBA) on isothermal crystallization kinetics of gemcitabine hydrochloride (GHCl) in frozen aqueous solutions was assessed by cold-stage microscopy. Addition of TBA (0%-5%, w/w) increased the value of Johnson-Mehl-Avrami rate constant (1.3-33.3 h⁻¹) and reduced the Avrami exponent (2.5-1.0). Thermodynamic parameters [enthalpy (ΔH(‡)), entropy (ΔS(‡)), and free energy (ΔG(‡)) of activation], calculated using Arrhenius and Eyring-Polanyi equations, established that TBA (2%, w/w) accelerated GHCl crystallization by reducing its ΔH(‡) (53.9 cf. 96.5 kJ/mol⁻¹) and ΔG(‡) (68.5 cf. 74.9 kJ/mol⁻¹). Further, to explore insights into the effect of TBA on nucleation and crystal growth of GHCl, crystallization kinetics data were deconvolved using Finke-Watzky model. This revealed that addition of TBA decreased ΔH(‡) of nucleation and increased ΔS(‡) of crystal growth, thereby reducing ΔG(‡) of nucleation and crystal growth by 11.7% and 4.2%, respectively. Finkey-Watzky model also predicted a reduction in the crystal size upon TBA addition, which was confirmed by comparing particle size of GHCl lyophilized in the presence and absence of TBA. In conclusion, TBA reduces ΔG(‡) of nucleation and crystal growth in a differential manner, thereby enhancing the crystallization kinetics of GHCl and affecting its morphological features. PMID:25393155

  11. Probe diffusion in polymer solutions and hydrogels using fluorescence correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Michelman-Ribeiro, Ariel; Boukari, Hacene; Horkay, Ferenc; Nossal, Ralph

    2006-03-01

    We apply fluorescence correlation spectroscopy (FCS) to measure the diffusion of small fluorescent probes (TAMRA, Mw = 430 Da; dextran, Mw = 10 kDa) in poly(vinyl alcohol) (PVA) solutions and hydrogels. PVA is a linear, neutral, biocompatible polymer, whose hydrogels have many biotechnology applications, such as drug-delivery devices and tissue scaffolds. The FCS measurements indicate that the probe diffusion decreases when the polymer solution is cross-linked. Further, the more the polymer chains are cross-linked, the slower the particles diffuse. These results suggest that the cross-link density, which is often ignored in the analysis of probe diffusion data in gels, must be taken into account. Remarkably, we find that the apparent diffusion time and the elastic modulus of the gels show a linear correlation.

  12. The plasticizing mechanism and effect of calcium chloride on starch/poly(vinyl alcohol) films.

    PubMed

    Jiang, Xiancai; Jiang, Ting; Gan, Lingling; Zhang, Xiaofei; Dai, Hua; Zhang, Xi

    2012-11-01

    Starch/poly(vinyl alcohol) (PVA) films were prepared with calcium chloride (CaCl(2)) as the plasticizer. The micro morphology of pure starch/PVA film and CaCl(2) plasticized starch/PVA film was observed by scanning electron microscope. The interaction between CaCl(2) and starch/PVA molecules was investigated by Fourier transform infrared spectroscopy. The influence of CaCl(2) on the crystalline, thermal and mechanical properties of starch/PVA films was studied by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, and tensile testing, respectively. The results indicated that CaCl(2) could interact with starch and PVA molecules and then effectively destroy the crystals of starch and PVA. Starch/PVA films plasticized with CaCl(2) became soft and ductile, with lower tensile strength and higher elongation at break compared with pure starch/PVA film. The water content of starch/PVA film would increase with the addition of CaCl(2). This is an important cause of the plasticization of CaCl(2) on starch/PVA film. PMID:22944433

  13. [Disinfection efficacy of hand hygiene based on chlorhexidine gluconate content and usage of alcohol-based hand-rubbing solution].

    PubMed

    Tanaka, Ippei; Watanabe, Kiyoshi; Nakaminami, Hidemasa; Azuma, Chihiro; Noguchi, Norihisa

    2014-01-01

    Recently, the procedure for surgical hand hygiene has been switching to a two-stage method and hand-rubbing method from the traditional hand-scrubbing method. Both the two-stage and hand-rubbing methods use alcohol-based hand-rubbing after hand washing. The former requires 5 min of antiseptic hand washing, and the latter 1 min of nonantiseptic hand washing. For a prolonged bactericidal effect in terms of surgical hand hygiene, chlorhexidine gluconate (CHG) has been noted due to its residual activity. However, no detailed study comparing the disinfection efficacy and prolonged effects according to different contents of CHG and the usage of alcohol-based hand-rubbing has been conducted. The glove juice method is able to evaluate disinfection efficacy and prolonged effects of the disinfectants more accurately because it can collect not only transitory bacteria but also normal inhabitants on hands. In the present study, we examined the disinfection efficacy and prolonged effects on alcohol-based hand-rubbing containing CHG by six hand-rubbing methods and three two-stage methods using the glove juice method. In both methods, 3 mL (one pump dispenser push volume) alcohol-based hand-rubbing solution containing 1% (w/v) CHG showed the highest disinfection efficacy and prolonged effects, and no significant difference was found between the hand-rubbing and two-stage methods. In the two methods of hand hygiene, the hand-rubbing method was able to save time and cost. Therefore, the data strongly suggest that the hand-rubbing method using a one pump dispenser push volume of alcohol-based hand-rubbing solution containing 1% (w/v) CHG is suitable for surgical hand hygiene. PMID:25366919

  14. Behavior of Ni2+ cations in aqueous and alcohol solutions of NiCl2 · 6H2O

    NASA Astrophysics Data System (ADS)

    Petkova, P.; Nedkov, V.; Vasilev, P.; Ismailov, I.

    2014-09-01

    We have investigated the optical properties of Ni2+ cations in aqueous and alcohol solutions of NiCl2 · 6H2O at room temperature. We measured the absorption spectra of these two types of solutions in the spectral region 395-795 nm. The Racah’s parameters and the exchange integrals of the aqueous complex [Ni(H2O)6]2+ have been calculated. The parameters Dq, Dt and Ds are also calculated on the basis of our experimental data. The parameters δσ and δπ, connected with the symmetry of the complex, are determined.

  15. Stable TEMPO and ABNO Catalyst Solutions for User-Friendly (bpy)Cu/Nitroxyl-Catalyzed Aerobic Alcohol Oxidation.

    PubMed

    Steves, Janelle E; Stahl, Shannon S

    2015-11-01

    Two solutions, one consisting of bpy/TEMPO/NMI and the other bpy/ABNO/NMI (bpy =2,2'-bipyridyl; TEMPO = 2,2,6,6-tetramethylpiperidine N-oxyl, ABNO = 9-azabicyclo[3.3.1]nonane N-oxyl; NMI = N-methylimidazole), in acetonitrile are shown to have good long-term stability (≥1 year) under air at 5 °C. The solutions may be combined in appropriate quantities with commercially available [Cu(MeCN)4]OTf to provide a convenient catalyst system for the aerobic oxidation of primary and secondary alcohols. PMID:26457658

  16. Development of a complex hydrogel of hyaluronan and PVA embedded with silver nanoparticles and its facile studies on Escherichia coli.

    PubMed

    Zhang, Fei; Wu, Juan; Kang, Ding; Zhang, Hongbin

    2013-01-01

    Novel nanocomposite hydrogels composed of hyaluronan (HA), poly(vinyl alcohol) (PVA) and silver nanoparticles were prepared by several cycles of freezing and thawing. The nanocomposite was then characterised using Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (XRD) and scanning electron microscopy (SEM). The complex hydrogels consisted of semi-interpenetrating network structures, with PVA microcrystallines as junction zones. By increasing the HA content, the crystallinity and melting temperature of the complex hydrogels decreased, whereas the glass transition temperatures of these materials increased because of the steric hindrance of HA and the occurrence of intermolecular interactions through hydrogen bonding between HA and PVA in the complex hydrogels. Swelling studies showed that in comparison with the swelling properties of the cryogels from PVA alone, those of the complex hydrogels can be significantly improved and presented in a pH-sensitive manner. In addition, silver nanoparticles were synthesised through UV-initiated photoreduction with HA functioning as a reducing agent and stabiliser. The silver nanoparticles were then incorporated in situ into the HA/PVA complex hydrogel matrix. The size and morphology of the as-prepared Ag nanoparticles were investigated through ultraviolet-visible light spectroscopy, transmission electron microscopy, XRD and thermogravimetric analysis. The experimental results indicated that silver nanoparticles 20-50 nm in size were uniformly dispersed in the hydrogel matrix. The antibacterial effects of the HA/PVA/Ag nanocomposite hydrogel against Escherichia coli were evaluated. The results show that this nanocomposite hydrogel possesses high antibacterial property and has a potential application as a wound dressing material. PMID:23829455

  17. Enhanced mechanical, thermal and antimicrobial properties of poly(vinyl alcohol)/graphene oxide/starch/silver nanocomposites films.

    PubMed

    Usman, Adil; Hussain, Zakir; Riaz, Asim; Khan, Ahmad Nawaz

    2016-11-20

    In the present work, synthesis of poly(vinyl alcohol)/graphene oxide/starch/silver (PVA/GO/Starch/Ag) nanocomposites films is reported. Such films have been characterized and investigated for their mechanical, thermal and antimicrobial properties. The exfoliation of GO in the PVA matrix occurs owing to the non-covalent interactions of the polymer chains of PVA and hydrophilic surface of the GO layers. Presence of GO in PVA and PVA/starch blends were found to enhance the tensile strength of the nanocomposites system. It was found that the thermal stability of PVA as well as PVA/starch blend systems increased by the incorporation of GO where strong physical bonding between GO layers and PVA/starch blends is assumed to cause thermal barrier effects. Antimicrobial properties of the prepared films were investigated against Escherichia coli and Staphylococcus aureus. Our results show enhanced antimicrobial properties of the prepared films where PVA-GO, PVA-Ag, PVA-GO-Ag and PVA-GO-Ag-Starch showed antimicrobial activity in ascending order. PMID:27561532

  18. Nanosecond laser irradiation synthesis of CdS nanoparticles in a PVA system

    NASA Astrophysics Data System (ADS)

    Onwudiwe, Damian C.; Krüger, Tjaart P. J.; Oluwatobi, Oluwafemi S.; Strydom, Christien A.

    2014-01-01

    We herein report a modified, in situ photolytic process for the nucleation and growth of cadmium sulphide nanoparticles in the presence of an optically transparent and semicrystalline polyvinyl alcohol (PVA) polymer matrix. The laser causes a localized decomposition of the precursor species in the immediate vicinity of the polymer leading to highly confined nanocrystals. The as-synthesized PVA-CdS nanocomposite were characterized using UV-vis absorption and photoluminescence spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HRTEM) and powdered X-ray diffraction (XRD). Strong blue shift in the band gap was observed in UV visible absorption spectrum indicating the size confinement. The influence of deposition temperature (25-200 °C) on the optical properties, microstructure, and thermal stability was also investigated. Thermal decomposition behaviors of these composites exhibit decreased thermal stability as indicated by the shift in the decomposition temperature of the pure PVA. XRD patterns revealed a reduction in the crystallinity of the polymer due to the entrapped particles. The nanocomposites showed the existence of both cubic and hexagonal phases.

  19. Graphene nanoribbon-PVA composite as EMI shielding material in the X band.

    PubMed

    Joshi, Anupama; Bajaj, Anil; Singh, Rajvinder; Alegaonkar, P S; Balasubramanian, K; Datar, Suwarna

    2013-11-15

    A very thin graphene nanoribbon/polyvinyl alcohol (GNR/PVA) composite film has been developed which is light weight and requires a very low concentration of filler to achieve electromagnetic interference (EMI) shielding as high as 60 dB in the X band. Atomic force microscope studies show very well conjugated filler concentration in the PVA matrix for varying concentrations of GNR supported by Raman spectroscopy data. The films show 14 orders of increase in conductivity with a GNR concentration of 0.75% [corrected] in PVA. This is possible because of the interconnected GNR network providing a very low percolation threshold as observed from the electrical measurements. Local density of states study of GNR using scanning tunnelling spectroscopy shows the presence of localized states near the Fermi energy. There are multiple advantages of GNR as an EMI shielding material in a polymer matrix. It has good dispersion in water, the conductive network in the composite shows very high electrical conductivity for a very low concentration of GNR and the presence of localized density of states near Fermi energy provides the spin states required for the absorbance of radiation energy in the X band. PMID:24140728

  20. Graphene nanoribbon-PVA composite as EMI shielding material in the X band

    NASA Astrophysics Data System (ADS)

    Joshi, Anupama; Bajaj, Anil; Singh, Rajvinder; Alegaonkar, P. S.; Balasubramanian, K.; Datar, Suwarna

    2013-11-01

    A very thin graphene nanoribbon/polyvinyl alcohol (GNR/PVA) composite film has been developed which is light weight and requires a very low concentration of filler to achieve electromagnetic interference (EMI) shielding as high as 60 dB in the X band. Atomic force microscope studies show very well conjugated filler concentration in the PVA matrix for varying concentrations of GNR supported by Raman spectroscopy data. The films show 14 orders of increase in conductivity with a GNR concentration of 0.0075 wt% in PVA. This is possible because of the interconnected GNR network providing a very low percolation threshold as observed from the electrical measurements. Local density of states study of GNR using scanning tunnelling spectroscopy shows the presence of localized states near the Fermi energy. There are multiple advantages of GNR as an EMI shielding material in a polymer matrix. It has good dispersion in water, the conductive network in the composite shows very high electrical conductivity for a very low concentration of GNR and the presence of localized density of states near Fermi energy provides the spin states required for the absorbance of radiation energy in the X band.

  1. Preparation and characterization of electrical conductive PVA based materials for peripheral nerve tube-guides.

    PubMed

    Gonçalves, C; Ribeiro, J; Pereira, T; Luís, A L; Mauricio, A C; Santos, J D; Lopes, M A

    2016-08-01

    Peripheral nerve regeneration is a serious clinical problem. Presently, there are several nerve tube-guides available in the market, however with some limitations. The goal of this work was the development of a biomaterial with high electrical conductivity to produce tube-guides for nerve regeneration after neurotmesis injuries whenrver an end-to-end suture without tension is not possible. A matrix of poly(vinyl alcohol) (PVA) was used loaded with the following electrical conductive materials: COOH-functionalized multiwall carbon nanotubes (MWCNTs), poly(pyrrole) (PPy), magnesium chloride (MgCl2 ), and silver nitrate (AgNO3 ). The tube-guide production was carried out by a freezing/thawing process (physical crosslinking) with a final annealing treatment. After producing the tube-guide for nerve regeneration, the physicochemical characterization was performed. The most interesting results were achieved by loading PVA with 0.05% of PPy or COOH- functionalized CNTs. These tubes combined the electrical conductivity of carbon nanotubes (CNTs) and PPy with the biocompatibility of PVA matrix, with potential clinical application for nerve regeneration. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1981-1987, 2016. PMID:27027727

  2. Structural and phase transition changes of sodium dodecyl sulfate micellar solution in alcohols probed by small-angle neutron scattering (SANS)

    SciTech Connect

    Putra, Edy Giri Rachman; Patriati, Arum

    2015-04-16

    Small-angle neutron scattering (SANS) measurements on 0.3M sodium dodecyl sulfate (SDS) micellar solutions have been performed in the presence of n-alcohols, from ethanol to decanol at different alcohol concentrations, 2–10 wt%. The ellipsoid micellar structure which occurred in the 0.3M SDS in aqueous solution with the size range of 30–50 Å has different behavior at various hydrocarbon chain length and concentration of alcohols. At low concentration and short chain-length of alcohols, such as ethanol, propanol, and butanol, the size of micelles reduced and had a spherical-like structure. The opposite effect occurred as medium to long chain alcohols, such as hexanol, octanol and decanol was added into the 0.3M SDS micellar solutions. The micelles structure changed to be more elongated in major axis and then crossed the critical phase transition from micellar solution into liquid crystal phase as lamellar structure emerged by further addition of alcohols. The inter-lamellar distances were also depending on the hydrocarbon chain length and concentration of alcohols. In the meantime, the persistent micellar structures occurred in addition of medium chain of n-alcohol, pentanol at all concentrations.

  3. On the Development of Thermally Stable Semi-IPNs of PVA and PAN using IR, DSC and XRD Studies

    NASA Astrophysics Data System (ADS)

    Deshpande, Deepti S.; Bajpai, R.; Bajpai, A. K.

    2011-07-01

    A novel biopolymer based Semi-IPN of polyvinyl alcohol (PVA) and polycrylonitrile (PAN) were synthesized in various proportions by redox polymerization and analyzed thermally by differential scanning calorimetry (DSC). DSC thermograms shows good thermal stability, as a result of incorporation of acrylonitrile as the second network. The structural and morphological study of these semi-IPNs by FTIR and XRD technique, respectively, were correlated. The approach seems to be beneficial for various biomedical applications.

  4. 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.

  5. Controllable layer-by-layer assembly of PVA and phenylboronic acid-derivatized chitosan.

    PubMed

    Zhang, Dan; Yu, Guanghua; Long, Zhu; Yang, Guihua; Wang, Bin

    2016-04-20

    Phenylboronic acid-derivatized chitosan (chitosan-PBA) were prepared by grafting small molecules bearing phenylboronic acid groups onto chitosan with N-hydroxysuccinimide (NHS) and N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) as a coupling reagent pair. Self-assembly multilayer thin films of chitosan-PBA and poly(vinyl alcohol) were subsequently produced under pH control on supporting surfaces, either a silicon wafer or polystyrene latex particles. The driving force of the self-assembly was the ester formation of phenylboronic acid containing polymers with PVA, which can be "turned off" by simple pH control. PMID:26876848

  6. Enhanced proton conductivity by the influence of modified montmorillonite on poly (vinyl alcohol) based blend composite membranes

    NASA Astrophysics Data System (ADS)

    Palani, P. Bahavan; Abidin, K. Sainul; Kannan, R.; Rajashabala, S.; Sivakumar, M.

    2016-05-01

    The highest proton conductivity value of 0.0802 Scm-1 is obtained at 6wt% of protonated MMT added to the PVA/PEG blends. The polymer blend composite membranes are prepared with varied concentration of Poly vinyl alcohol (PVA), Poly ethylene glycol (PEG) and Montmorillonite (MMT) by solution casting method. The Na+ MMT was modified (protonated) to H+ MMT with ion exchange process. The prepared membranes were characterized by using TGA, FTIR, XRD, Ion Exchange Capacity, Water/Methanol uptake, swelling ratio and proton conductivity. The significant improvements in the hydrolytic stability were observed. In addition, thermal stability of the composite membranes were improved and controlled by the addition of MMT. All the prepared membranes are shown appreciable values of proton conductivity at room temperature with 100% relative humidity.

  7. Cylindrical diffractive lenses recorded on PVA/AA photopolymers

    NASA Astrophysics Data System (ADS)

    Fernández, R.; Gallego, S.; Márquez, A.; Navarro-Fuster, V.; Francés, J.; Neipp, C.; Beléndez, A.; Pascual, I.

    2016-04-01

    Photopolymers are optical recording materials appealing for many different applications such as holography, data storage, interconnectors, solar concentrations, or wave-guides fabrication. Recently the capacity of photopolymers to record diffractive optical elements (DOE's) has been investigated. Different authors have reported proposes to record DOE like fork gratings, photonics structures, lenses, sinusoidal, blazed or fork gratings. In these experiments there are different experimental set-ups and different photopolymers. In this work due to the improvement in the spatial light modulation technology together with the photopolymer science we propose a recording experimental system of DOE using a Liquid Cristal based on Silicon (LCoS) display as a master to store complex DOE like cylindrical lenses. This technology permits us an accurate control of the phase and the amplitude of the recording beam, with a very small pixel size. The main advantage of this display is that permit us to modify the DOE automatically, we use the software of the LCoS to send the voltage to each pixel In this work we use a photopolymer composed by acrylamide (AA) as polymerizable monomer and polyvinyl alcohol (PVA). We use a coverplated and index matched photopolymer to avoid the influence of the thickness variation on the transmitted light. In order to reproduce the material behaviour during polymerization, we have designed our model to simulate cylindrical lenses and used Fresnel propagation to simulate the light propagation through the DOE and analyze the focal plane and the properties of the recorded lenses.

  8. Functional data analysis of experimental parameters obtained in PVA doped CdCl2 polymer composites

    NASA Astrophysics Data System (ADS)

    Prakash, M. B. Nanda; Urs, Gopal Krishne; Somashekar, R.

    2016-05-01

    Using solution casting method, PVA based polymer composites films with various concentrations of CdCl2 were prepared. Prepared polymer composites films were investigated using XRD. Crystallite size for different concentrations of CdCl2 are computed here using Williamson and Hall plot (WH plot), an in-house program developed by us. To correlate between two independent physical parameters size and conductivity, we have chosen functional data analysis to estimate the maxima and minima in these polymer composites systems.

  9. Impact of electron-beam irradiation on free-volume related microstructural properties of PVA:NaBr polymer composites

    NASA Astrophysics Data System (ADS)

    Ismayil; Vasachar, Ravindrachary; Bhajantri, Rajashekhar F.; Dhola, Praveena S.; Sanjeev, Ganesh

    2015-01-01

    Sodium Bromide doped Poly(vinyl alcohol) (PVA:NaBr, 80:20) polymer composite films were prepared using a solution casting method. These films were subjected to 8 MeV electron beam radiation at a dose of up to 300 kGy in air at room temperature. The free volume related microstructural and electrical properties of these irradiated films were studied using various characterization methods, such as positron annihilation lifetime spectroscopy (PALS) and AC & DC conductivity measurement techniques. The variations in the positron lifetime data indicate that the free-volume related properties of the doped polymer are affected by irradiation. From the results, it is found that at lower doses, a cross-linking network provides hopping sites for Na+ ions, and at higher doses, the chain-scission process facilitates ionic transport through segmental motion. Thus, the free volume around the polymer chain leads to mobility of the ions as well as the polymer segments and hence contributes to the enhancement of conductivity.

  10. NOVEL METALLIC AND BIMETALLIC CROSS-LINKED POLY (VINYL ALCOHOL) NANOCOMPOSITES PREPARED UNDER MICROWAVE IRRADIATION

    EPA Science Inventory

    A facile microwave irradiation approach that results in a cross-linking reaction of poly (vinyl alcohol) (PVA) with metallic and bimetallic systems is described. Nanocomposites of PVA cross-linked metallic systems such as Pt, Cu, and In and bimetallic systems such as Pt-In, Ag-P...

  11. Boronic acid as an efficient anchor group for surface modification of solid polyvinyl alcohol.

    PubMed

    Nishiyabu, Ryuhei; Shimizu, Ai

    2016-07-28

    We report the use of boronic acid as an anchor group for surface modification of solid polyvinyl alcohol (PVA); the surfaces of PVA microparticles, films, and nanofibers were chemically modified with boronic acid-appended fluorescent dyes through boronate esterification using a simple soaking technique in a short time under ambient conditions. PMID:27311634

  12. 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.

  13. 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.

  14. Role of single-walled carbon nanotubes on ester hydrolysis and topography of electrospun bovine serum albumin/poly(vinyl alcohol) membranes.

    PubMed

    Ford, Ericka N J; Suthiwangcharoen, Nisaraporn; D'Angelo, Paola A; Nagarajan, Ramanathan

    2014-07-23

    Electrospun membranes were studied for the chemical deactivation of threat agents by means of enzymatic proteins. Protein loading and the surface chemistry of hybrid nanofibers influenced the efficacy by which embedded enzymes could digest the substrate of interest. Bovine serum albumin (BSA), selected as a model protein, was electrospun into biologically active fibers of poly(vinyl alcohol), PVA. Single-walled carbon nanotubes (SWNTs) were blended within these mixtures to promote protein assembly during the process of electrospinning and subsequently the ester hydrolysis of the substrates. The SWNT incorporation was shown to influence the topography of PVA/BSA nanofibers and enzymatic activity against paraoxon, a simulant for organophosphate agents and a phosphorus analogue of p-nitrophenyl acetate (PNA). The esterase activity of BSA against PNA was uncompromised upon its inclusion within nanofibrous membranes because similar amounts of PNA were hydrolyzed by BSA in solution and the electrospun BSA. However, the availability of BSA along the fiber surface was shown to affect the ester hydrolysis of paraoxon. Atomic force microscopy images of nanofibers implicated the surface migration of BSA during the electrospinning of SWNT filled dispersions, especially as greater weight fractions of protein were added to the spinning mixtures. In turn, the PVA/SWNT/BSA nanofibers outperformed the nanotube free PVA/BSA membranes in terms of paraoxon digestion. The results support the development of electrospun polymer nanofiber platforms, modulated by SWNTs for enzyme catalytic applications relevant to soldier protective ensembles. PMID:25007411

  15. A novel electrospun membrane based on moxifloxacin hydrochloride/poly(vinyl alcohol)/sodium alginate for antibacterial wound dressings in practical application.

    PubMed

    Fu, Ruoqiu; Li, Chenwen; Yu, Caiping; Xie, Hong; Shi, Sanjun; Li, Zhuoheng; Wang, Qing; Lu, Laichun

    2016-03-01

    This study reports on the performance of sodium alginate (SA)/poly(vinyl alcohol) (PVA)/moxifloxacin hydrochloride (MH) nanofibrous membranes (NFM) capable of providing antibacterial agent delivery for wound-dressing applications. The aim of this work was to prepare antibacterial NFM with good permeability properties by employing PVA and SA as carriers. A group of 12% PVA/2% SA solutions blended in various ratios (8:2, 7:3, 6:4, 5:5 and 4:6, v/v) and containing 0.5, 1, 2 or 4 wt% MH were studied for electrospinning into nanoscale fibermats. The optimum ratio found to form smooth fibers with uniform fibrous features was 6:4. The drug release behavior of the electrospun, the antibacterial effects on Pseudomonas aeruginosa and Staphylococcus aureus and the animal wound dressing capabilities were also investigated. As much as 80% of the MH was released from the electrospun after 10 h of incubation at 37 °C. In addition, the NFM with 0.5 MH exhibited less activity, whereas those with higher concentrations of MH exhibited greater antibacterial effect. Furthermore, the MH-loaded electrospun accelerated the rate of wound dressing compared to other groups. The results of the in vitro and in vivo experiments suggest that MH/PVA/SA nanofibers might be an interesting bioactive wound dressing for clinical applications. PMID:24870202

  16. Effect of ethylene carbonate as a plasticizer on CuI/PVA nanocomposite: Structure, optical and electrical properties

    PubMed Central

    Mohamed, Shaimaa A.; Al-Ghamdi, A.A.; Sharma, G.D.; El Mansy, M.K.

    2013-01-01

    Layers of ethylene carbonate (EC) modified CuI/PVA polymer composites were prepared by growth of CuI nano-particles in an aqueous solution of PVA followed by casting at room temperature. The structural, thermal, optical, electrical and di-electrical characterization of polymer composites was investigated using different techniques. These investigations confirm the growth of CuI nano-particles and reduction of PVA crystallinity by increasing ethylene carbonate concentration. These results show that energy band gap and bulk conductivity increase while activation energy reduces with the increase of EC concentration in the composite. Moreover, the variation of the dielectric permittivity and dielectric loss with EC content are found to obey Debye dispersion relations. PMID:25685474

  17. Optical Properties of CdS/PVA Nanocomposite Films Synthesized using the Gamma-Irradiation-Induced Method

    NASA Astrophysics Data System (ADS)

    Alireza, Kharazmi; Elias, Saion; Nastaran, Faraji; Nayereh, Soltani; Arash, Dehzangi

    2013-05-01

    Monodispersed spherical CdS nanoparticles embedded into polyvinyl alcohol (PVA) films are synthesized by using an in-situ gamma-irradiation-induced method. The formation mechanism of CdS nanoparticles capped by two united cells of PVA is purposed by means of surrounding the CdS nanoparticles with OH bonds of the PVA chain. CdS nanoparticles are found to possess an unusual orthorhombic structure in monoclinic crystalline PVA. The polymer matrix affords protection from agglomeration and controls the particle size. It is found that the distribution of the prepared nanoparticles increases and a narrower size distribution is observed when the gamma radiation is varied from 10 to 50 kGy. While the average size of the nanoparticles is found to be less affected by the variation of the gamma radiation doses. The size range of the synthesized nanoparticles is 14±1 nm. The optical absorption spectra of synthesized CdS nanoparticles in a polymer matrix reveal the blue shift in the band gap energy with respect to CdS bulk materials owing to quantum confinement effect. The photoluminescence study of nanocomposite films shows the green emission arising from the crystalline defects.

  18. SeO II addition on PVA-based photopolymer for improving photostorage stabilities and diffraction efficiencies

    NASA Astrophysics Data System (ADS)

    Kim, Daeheum; Nam, Seungwoong; Yeo, Seungbyung; Lim, Jiyun

    2006-08-01

    Polyvinyl alcohol/Acrylamide(PVA/AA)based photopolymer systems modified with SeO II crystals were prepared and photostorage characteristics mainly including diffraction efficiencies were examined and compared with pure PVA/AA films using green laser light (532nm). The photosensitive films were composed of polymeric film-forming binder (PVA), monomer (acrylamide, AA), photoinitiator (triethanol amine, TEA), photosensitizer (Eosin YR), and SeO II crystals. The best optical recording characteristics were observed at the composition of: polymer binder (PVA) : AA : TEA : SeO II : Eosin Y = 1.0 : 0.3 : 0.225 : 0.1 : 0.0015. Diffraction efficiencies as high as 85% with energetic sensitivity of 0.5 mW/cm2 have been obtained in the photopolymer film, and the photopolymer film with SeO II showed higher diffraction efficiencies and lower initial sensitivity than the photopolymer film without SeO II. The morphology of SeO II was expected to be nano crystals since they didn't scatter optical lights and didn't show any peaks in X-ray diffraction spectra.

  19. Ectopic osteochondral formation of biomimetic porous PVA-n-HA/PA6 bilayered scaffold and BMSCs construct in rabbit.

    PubMed

    Qu, Dan; Li, Jihua; Li, Yubao; Khadka, Ashish; Zuo, Yi; Wang, Hang; Liu, Yiming; Cheng, Lin

    2011-01-01

    In this work, the novel poly vinyl alcohol/gelatin-nano-hydroxyapatite/polyamide6 (PVA-n-HA/PA6) bilayered scaffold with biomimetic properties for articular cartilage and subchondral bone is developed. Furthermore, when these osteochondral scaffolds were seeded with induced bone mesenchymal stem cells (BMSCs) and implanted at ectopic sites, showed the potential for an engineered cartilage tissue and the corresponding subchondral bone. BMSCs were expanded in vitro and induced to chondrogenic or osteogenic potential by culturing in suitable media for 14 days. Subsequently, these induced cells were seeded into PVA-n-HA/PA6 separately, and the constructs were implanted into the rabbit muscle pouch for upto 12 weeks. Ectopic neocartilage formation in the PVA layer and reconstitution of the subchondral bone which remained confined within the n-HA/PA6 layer with the alteration of the cellular phenotype were identified with Masson's trichrome stain. Simultaneously, the RT-PCR results confirmed the expression of specific extracellular matrix (ECM) markers for cartilaginous tissue, such as collagen type II (Col-II), or alternatively, markers for osteoid tissue, such as collagen type I (Col-I) at the corresponding layers. During ectopic implantation, the underlying subchondral bone layer was completely integrated with the cartilage layer. The result from the ectopic osteochondral scaffolds implantation suggests that PVA-n-HA/PA6 with induced BMSCs is a possible substitute with potential in cartilage repair strategies. PMID:20967773

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

    PubMed Central

    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. PMID:23012555

  1. Comparison of Chain Conformation of Poly(vinyl alcohol) in Solutions and Melts from Quantum Chemistry Based Molecular Dynamics Simulations

    NASA Technical Reports Server (NTRS)

    Jaffe, Richard; Han, Jie; Matsuda, Tsunetoshi; Yoon, Do; Langhoff, Stephen R. (Technical Monitor)

    1997-01-01

    Confirmations of 2,4-dihydroxypentane (DHP), a model molecule for poly(vinyl alcohol), have been studied by quantum chemistry (QC) calculations and molecular dynamics (MD) simulations. QC calculations at the 6-311G MP2 level show the meso tt conformer to be lowest in energy followed by the racemic tg, due to intramolecular hydrogen bond between the hydroxy groups. The Dreiding force field has been modified to reproduce the QC conformer energies for DHP. MD simulations using this force field have been carried out for DHP molecules in the gas phase, melt, and CHCl3 and water solutions. Extensive intramolecular hydrogen bonding is observed for the gas phase and CHCl3 solution, but not for the melt or aqueous solution, Such a condensed phase effect due to intermolecular interactions results in a drastic change in chain conformations, in agreement with experiments.

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

    PubMed Central

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

    2012-01-01

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

  3. [Alcohol and drugs in Central Europe--problems and possible solutions].

    PubMed

    Nespor, K; Cs emy, L

    1994-08-22

    The high alcohol consumption and increasing abuse of other addictive inducing substances in Central Europe calls for broadley conceived preventive programmes and cheap and widely applicable therapeutic strategies (early treatment at the first contact level, self-help manuals, self-aid organizations). Social instability along with greater availability of alcohol and drugs create a dangerous combination. In addition to strategies of stress prevention at the societal level also strategy at the individual level is important (e.g. relaxation training, yoga, psychotherapy). It is also important to change the "image" of western society and commercial interests of those who make profits on alcohol and drugs should be under control and advertising should be greatly restricted if not prohibited. Prevention of problems caused by alcohol and drugs in particular in youths must be combined and really effective strategies should be used such as peer programmes. The authors mention also their own preventive programme FIT IN and print materials oriented specifically on certain population groups. PMID:7923324

  4. Fetal Alcohol Syndrome: Understanding the Problem; Understanding the Solution; What Indian Communities Can Do.

    ERIC Educational Resources Information Center

    Streissguth, Ann P.

    1994-01-01

    Summarizes facts about fetal alcohol syndrome (FAS), including physical and mental symptoms; cause; prevalence overall and in Indian communities; and problems of infants, children, and adults with FAS. Emphasizes the importance of public awareness, professional education, and provision of community services to prevent FAS. Outlines specific…

  5. Fabrication of ZnO nanorod/p-GaN high-brightness UV LED by microwave-assisted chemical bath deposition with Zn(OH)2-PVA nanocomposites as seed layer

    NASA Astrophysics Data System (ADS)

    Hassan, J. J.; Mahdi, M. A.; Yusof, Y.; Abu-Hassan, H.; Hassan, Z.; Al-Attar, H. A.; Monkman, A. P.

    2013-03-01

    Chemical solution deposition is a low-temperature and possibly the lowest-cost method of growing ZnO nanorods on a GaN substrate. However, most reported methods leave an interface layer between the grown ZnO nanorods and substrate, which can interfere with light emission and extraction. Here we report the growth of high-quality, vertically aligned ZnO nanorods directly on a p-type GaN substrate, with no interface layer, by microwave-assisted chemical bath deposition using a polyvinyl alcohol (PVA)-Zn(OH)2 nanocomposites as the seed layer. X-ray diffraction and field-emission scanning electron microscopy confirmed the high quality of the nanorods in addition to the narrow and high-intensity UV peak of the photoluminescence spectrum. Three different filling insulator materials, poly methyl methacrylate (PMMA), SiO2, and PVA, were used to fabricate n-ZnO nanorod/p-GaN thin film LED structures. The electroluminescence (EL) properties for these three devices showed different emission peaks, which mainly originated from the recombination of free carriers at the two sides of the heterojunction. All devices showed excellent LED performance under forward and reverse bias; the PMMA device showed EL peaks in the UV-blue region, and the SiO2 device displayed EL peaks in the UV and green regions, respectively.

  6. Mechanical and electromagnetic interference shielding Properties of poly(vinyl alcohol)/graphene and poly(vinyl alcohol)/multi-walled carbon nanotube composite nanofiber mats and the effect of Cu top-layer coating.

    PubMed

    Fujimori, Kazushige; Gopiraman, Mayakrishnan; Kim, Han-Ki; Kim, Byoung-Suhk; Kim, Ick-Soo

    2013-03-01

    We report the mechanical property and electromagnetic interference shielding effectiveness (EMI SE) of poly(vinyl alcohol) (PVA)/graphene and PVA/multi-walled carbon nanotube (MWCNT) composite nanofibers prepared by electrospinning. The metal (Cu) was deposited on the resultant PVA composite nanofibers using metal deposition technique in order to improve the mechanical properties and EMI shielding properties. The resulting PVA composite nanofibers and Cu-deposited corresponding nanofibers were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and wide angle X-ray diffraction (WAXD). Tensile tests were performed on the PVA/graphene and PVA/MWCNT composite nanofibers. The tensile strength of the PVA/graphene and PVA/MWCNT composite nanofibers was found to be 19.2 +/- 0.3 MPa at graphene content - 6.0 wt% and 12.2 +/- 0.2 MPa at MWCNT content - 3.0 wt%, respectively. The EMI SE of the Cu-deposited PVA/graphene composite nanofibers was significantly improved compared to pure PVA/graphene composite nanofibers, and also depended on the thickness of Cu metal layer deposited on the PVA composite nanofibers. PMID:23755586

  7. Effect of sonication on the mechanical properties of poly (vinyl alcohol)/carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Truong, Van-Tan; Tsang, Kelly M. C.; Keough, Shannon J.; St John, Nigel A.

    2006-12-01

    Several sonication procedures were performed on multi-walled carbon nanotubes (MWNTs) in water by varying the length of time, the output power and the type of sonicating horn. Depending on the sonicating conditions, the multi-walled carbon nanotubes (MWNTs) could be well or poorly exfoliated and dispersed. Poly (vinyl alcohol) (PVA) and MNWT (0.5 wt%) composites were cast from the PVA/MWNT aqueous mixture. Enhancement of the mechanical properties of the composites was related to two factors: (1) crystallinity formed at the PVA and MWNT interface and (2) the size of nanotube agglomerates. The poorly dispersed solution produced nanotube agglomerates with the size of 50-100 μm that did not induce crystallization at the polymer/nanotube interface. They became stress concentrators reducing the Young's modulus and the tensile strength. Optimized sonication procedures resulted in well-dispersed nanotube agglomerates of submicron dimensions efficiently enhancing the mechanical properties. As centrifugation facilitated the removal of large agglomerates, noticeable enhancement of mechanical properties of the composites was achieved.

  8. Antimicrobial activity of poly(vinyl alcohol)-poly(acrylic acid) electrospun nanofibers.

    PubMed

    Santiago-Morales, Javier; Amariei, Georgiana; Letón, Pedro; Rosal, Roberto

    2016-10-01

    Electrospun nanofibers were prepared from blends of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA). The fibers were stabilized by heat curing at 140°C via anhydride and ketone formation and crosslinking esterification. The antimicrobial effect was assessed using strains of Escherichia coli and Staphylococcus aureus by tracking their capacity to form colonies and their metabolic impairment upon contact with PAA/PVA membranes. Membranes containing >35wt.% PAA displayed significant antibacterial activity, which was particularly high for the gram-positive S. aureus. All membranes were negatively charged, with surface ζ-potential in the (-34.5)-(-45.6)mV range, but the electrostatic interaction with the negatively charged cells was not the reason for the antimicrobial effect. Neither pH reduction nor the passing of non-crosslinked polymers to the solution affected microbial growth. The antibacterial activity was attributed to the chelation of the divalent cations stabilizing the outer cell membrane. The effect on gram-positive bacteria was attributed to the destabilization of the peptidoglycan layer. The sequestration of divalent cations was demonstrated with experiments in which calcium and a chelating agent were added to the cultures in contact with membranes. The damage to bacterial cells was tracked by measuring their surface charge and the evolution of intracellular calcium during the early stages after contact with PAA/PVA membranes. PMID:27318959

  9. Facile synthesis of silver nanoparticles-modified PVA/H4SiW12O40 nanofibers-based electrospinning to enhance photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Sui, Chunhong; Li, Chao; Guo, Xiaohong; Cheng, Tiexin; Gao, Yukun; Zhou, Guangdong; Gong, Jian; Du, Jianshi

    2012-07-01

    Regarding poly(vinyl alcohol)/silicotungstic acid (PVA/H4SiW12O40) gel as precursor, the silver nanoparticles (NPs) were selectively deposited on the surface of the PVA/H4SiW12O40 nanofibers by using electrospinning and photoreduction methods. X-ray photoelectron spectroscopy, Fourier transformation infrared spectroscopy, and UV-vis diffuse reflectance spectroscopy were used to affirm the structure and formation of tri-component nanohybrids. Field environmental scanning electron microscope and transmission electron microscopy indicate that the average diameter of silver NPs was changed from 25 nm to 50 nm, with decreasing the relative concentration of SiW12 in the as-electrospun nanofibers. The nanocomposites exhibit excellent photocatalytic activity in degradation of Rhodamine B. This result arises from the synergistic effects and the large specific surface areas of Ag/PVA/H4SiW12O40 tri-component nanohybrids.

  10. Utilization of cation exchange resins for the isolation and separation of transplutonium elements from others in aqueous and non aqueous-alcohol solutions of hydrochloric and nitric acids

    SciTech Connect

    Guseva, L.I.; Tikhomirova, G.S.

    1985-07-01

    The authors study the sorption of several transplutonium and fission elements on cation exchange resins in relation to the acid concentration and content of alcohol in solution. They observe a significant increase in sorption of the TPE on the cation exchanges from nitric acid solutions containing more than 50% of alcohol. On the basis of the experimental results they determine the optimum conditions for the concentration of TPE on cation exchangers with their subsequent separation from certain fission and other elements by means of hydrochloric acid and nitric acid solutions.

  11. Photoinduced crystallization of calcium carbonate from a homogeneous precursor solution in the presence of partially hydrolyzed poly(vinyl alcohol)

    NASA Astrophysics Data System (ADS)

    Nishio, Takashi; Naka, Kensuke

    2015-04-01

    Photoinduced crystallization of calcium carbonate (CaCO3) was demonstrated by the photodecarboxylation of ketoprofen (KP, 2-(3-benzoylphenyl)propionic acid) under alkaline conditions (pH 10). In this method, a homogeneous solution comprising KP, calcium chloride, ammonia, and partially hydrolyzed poly(vinyl alcohol) (PVAPS, degree of saponification: 86.5-89.0 mol %) was used as the precursor solution and was exposed to ultraviolet (UV) irradiation for different time periods. Thermogravimetric analysis of the obtained xerogels showed that increasing the UV irradiation time increased the amount of CaCO3 formed and the complete conversion of calcium ions to calcite was achieved after 50 min of UV irradiation. Furthermore, solid phase analyses suggested that nanometer-to-micron-sized calcite crystals were formed and dispersed in the obtained PVAPS matrix.

  12. Enthalpy pair coefficients of interaction for DL-valine in aqueous solutions of polyatomic alcohols at 298 K

    NASA Astrophysics Data System (ADS)

    Mezhevoi, I. N.; Badelin, V. G.

    2013-12-01

    Integral enthalpies of dissolution Δsol H m of DL-valine are measured via calorimetry of dissolution in aqueous solutions of glycerol, ethylene glycol, and 1,2-propylene glycol. Standard values of the enthalpies of dissolution (Δsol H ○) and transfer (Δtr H ○) of amino acid from water to mixed solvent are calculated from the resulting experimental data. The enthalpy coefficients for pair interactions hxy of amino acid with polyatomic alcohol molecules are calculated using the McMillan-Meyer theory and have positive values. The obtained results are discussed in light of the theory of the predomination of various types of interactions in mixed solutions and the effect of structural features of interacting biomolecules on the thermochemical parameters of the dissolution of amino acids.

  13. Synthesis, characterization, and cytotoxicity of TMC-graft-poly(vinyl alcohol) copolymers.

    PubMed

    Martins, Alessandro F; Bueno, Pedro V A; Follmann, Heveline D M; Nocchi, Samara R; Nakamura, Celso V; Rubira, Adley F; Muniz, Edvani C

    2013-11-15

    N-trimethyl chitosan-graft-poly(vinyl alcohol) (TMC-g-PVA) copolymers were prepared. The grafting reactions were conducted in water changing the feed ratios of poly(vinyl alcohol)/6-O-succinate-N-trimethyl chitosan (PVA/STMC). The structure of TMC-g-PVA copolymers was characterized through (1)H NMR spectroscopy, thermogravimetric analysis (TGA/DTG), wide-angle X-ray scattering (WAXS) and scanning electron microscopy (SEM). The quaternization degree (DQ) and substitution degree (DS) of N-trimethyl chitosan (TMC) and 6-O-succinate-N-trimethyl chitosan (STMC) were determined by (1)H NMR, being the spectroscopy 14.0 and 5.5mol-% found, respectively. The viability of HCT-116 cancerous cells was investigated at different concentrations. The effect of PVA/STMC ratios on the cytotoxicity of the TMC-g-PVA copolymers was examined and the CC50 values determined for every case. PMID:23290305

  14. Horseradish peroxidase-catalyzed formation of hydrogels from chitosan and poly(vinyl alcohol) derivatives both possessing phenolic hydroxyl groups.

    PubMed

    Sakai, Shinji; Khanmohammadi, Mehdi; Khoshfetrat, Ali Baradar; Taya, Masahito

    2014-10-13

    Horseradish peroxidase-catalyzed cross-linking was applied to prepare hydrogels from aqueous solutions containing chitosan and poly(vinyl alcohol) derivatives both possessing phenolic hydroxyl groups (denoted as Ph-chitosan and Ph-PVA, respectively). Comparing the hydrogels prepared from the solution of 1.0% (w/v) Ph-chitosan and 3.0% (w/v) Ph-PVA and that of 3.0% (w/v) Ph-chitosan and 1.0% (w/v) Ph-PVA, the gelation time of the former hydrogel was 47 s, while was 10s longer than that of the latter one. The breaking point for the former hydrogel under stretching (114% strain) was approximately twice larger than that for the latter one. The swelling ratio of the former hydrogel in saline was about half of the latter one. Fibroblastic cells did not adhere on the former hydrogel but adhered and spread on the latter one. The growth of Escherichia coli cells was fully suppressed on the latter hydrogel during 48 h cultivation. PMID:25037368

  15. Optimizing the tensile properties of polyvinyl alcohol hydrogel for the construction of a bioprosthetic heart valve stent.

    PubMed

    Wan, W K; Campbell, G; Zhang, Z F; Hui, A J; Boughner, D R

    2002-01-01

    Although bioprosthetic heart valves offer the benefits of a natural opening and closing, better hemodynamics, and avoidance of life-long anticoagulant therapy, they nevertheless tend to fail in 10-15 years from tears and calcification. Several authors, including the present ones, have identified the rigid stent as a factor contributing to these failures. The ultimate solution is an artificial heart valve that has mechanical properties that allow it to move in conformity with the aortic root during the cardiac cycle, has superior hemodynamics, is nonthrombogenic, will last more than 20 years, and mitigates the need for anticoagulants. We have identified a polymer, polyvinyl alcohol (PVA) hydrogel, that has mechanical properties similar to soft tissue. The purpose of this research is to match the tensile properties of PVA to the porcine aortic root and to fabricate a stent prototype for a bioprosthetic heart valve with the use of the PVA hydrogel. Specimens of 15% w/w PVA were prepared by processing through 1-6 cycles of freezing (-20 degrees C) at 0.2 degrees C/min freeze rate and thawing (+20 degrees C) at different thawing rates (0.2 degrees C/min and 1 degrees C/min), for different holding times (1 and 6 h) at -20 degrees C. Subsequently tensile tests and stress-relaxation tests were conducted on the specimens. The different holding times at -20 degrees C demonstrated no difference in the result. The slower thawing rate improved the tensile properties but did not produce significant changes on the stress-relaxation properties. The nonlinear stress-strain curve for the PVA after the fourth freeze-thaw cycle matched the porcine aortic root within the physiological pressure range. The stress-relaxation curve for PVA also approximated the shape of the aortic root. The complex geometry of an artificial heart valve stent was successfully injection molded. These results, in combination with other preliminary findings for biocompatibility and fatigue behavior, suggest

  16. Controllable promotion of chondrocyte adhesion and growth on PVA hydrogels by controlled release of TGF-β1 from porous PLGA microspheres.

    PubMed

    Nie, Lei; Zhang, Guohua; Hou, Ruixia; Xu, Haiping; Li, Yaping; Fu, Jun

    2015-01-01

    Poly(vinyl alcohol) (PVA) hydrogels have been candidate materials for cartilage tissue engineering. However, the cell non-adhesive nature of PVA hydrogels has been a limit. In this paper, the cell adhesion and growth on PVA hydrogels were promoted by compositing with transform growth factor-β1 (TGF-β1) loaded porous poly(D,L-lactide-co-glycolide) (PLGA) microspheres. The porous microspheres were fabricated by a modified double emulsion method with bovine serum albumin (BSA) as porogen. The average pore size of microspheres was manipulated by changing the BSA/PLGA ratio. Such controllable porous structures effectively influenced the encapsulation efficiency (Eencaps) and release profile of TGF-β1. By compositing PVA hydrogels with such TGF-β1-loaded PLGA microspheres, chondrocyte adhesion and proliferation were significantly promoted in a controllable manner, as confirmed by fluorescent imaging and quantitative CCK-8 assay. That is, the chondrocyte proliferation was favored by using PLGA microspheres with high Eencaps of TGF-β1 or by increasing the PLGA microsphere content in the hydrogels. These results demonstrated a facile method to improve the cell adhesion and growth on the intrinsically cell non-adhesive PVA hydrogels, which may find applications in cartilage substitution. PMID:25437063

  17. Fabrication of Li2TiO3 pebbles using PVA-boric acid reaction for solid breeding materials

    NASA Astrophysics Data System (ADS)

    Park, Yi-Hyun; Cho, Seungyon; Ahn, Mu-Young

    2014-12-01

    Lithium metatitanate (Li2TiO3) is a candidate breeding material of the Helium Cooled Ceramic Reflector (HCCR) Test Blanket Module (TBM). The breeding material is used in pebble-bed form to reduce the uncertainty of the interface thermal conductance. In this study, Li2TiO3 pebbles were successfully fabricated by the slurry droplet wetting method using the cross-linking reaction between polyvinyl alcohol (PVA) and boric acid. The effects of fabrication parameters on the shaping of Li2TiO3 green body were investigated. In addition, the basic characteristics of the sintered pebble were also evaluated. The shape of Li2TiO3 green bodies was affected by slurry viscosity, PVA content and boric acid content. The grain size and average crush load of sintered Li2TiO3 pebble were controlled by the sintering time. The boron was completely removed during the final sintering process.

  18. Application of argon laser beam diffraction for determination of the properties of photoinduced processes in dyed PVA foils

    NASA Astrophysics Data System (ADS)

    Planner, Alfons; Runka, Tomasz; Skrzypczak, A.; Hara, M.; Miyake, J.

    2000-11-01

    It is shown that far field patterns of argon laser beam interacting with dyed foil of polyvinyl alcohol (PVA) provide information on the mechanism of local foil discoloration or at least on a few properties of this process. In particular far field patterns observations allow discernment if the process is reversible (or a superposition of reversible and irreversible processes), photothermal, photochemical or produce a stretching in sample (photoizomerisation). The effect was studied in PVA foil containing methyl red, photosynthetic bacteria, their fragments and pigments. Apart from indicating the possibility of using the far field patterns for discernment of the foil discoloration mechanisms, the results reported point to the perspectives of using the foil for laser beam modification, shift or modulation, as well as elements of optical memory.

  19. Qualification of European Triple-Junction Solar Cells with Astrium PVA Technology

    NASA Astrophysics Data System (ADS)

    Dettlaff, K.; Gerhard, A.; Paaramann, C.; Bals, A.; Zimmermann, W.; Fernandez, E.; Caon, A.

    2008-09-01

    During the last couple of years the application of triple junction GaInP/GaInAs/Ge solar cells for all kind of missions - LEO, GEO, MEO and inter-planetary missions - came to pass, replacing the Si solar cells and related processing parameters.Comprehensive qualification programs have been performed at Astrium in order to qualify the new generations of solar cell types with Astrium's PVA technology. The actual generation of European triple junction GaInP/GaInAs/Ge solar cells manufactured by AZUR SPACE has been successfully qualified in the frame of the ESA ARTES3 programe for GEO-applications like Eurostar 3000 and Alpha-Bus and in the frame of GalileoSat for a MEO orbit. The delta qualification of the 3G28-ID2* solar cell and the associated PVA technology for LEO is currently running for the ESA SWARM project which will have operational temperatures up to 140°C in combination with an ATOX environment. The high operational temperature in combination with the high number of thermal cycles is a challenge for the solar cell interconnection technology and for the integral diode (ID2*). Different solar cell interconnector technologies have to be used and a protection against the ATOX environment has to be implemented. A further challenge of the SWARM project is the requirement for extremely high magnetic cleanliness.This paper will present qualification test results and the technical solutions to overcome the outlined challenges on PVA level.

  20. Poly/vinyl alcohol/ membranes for reverse osmosis

    NASA Technical Reports Server (NTRS)

    Katz, M. G.; Wydeven, T., Jr.

    1981-01-01

    A description is presented of the results of studies of the water and salt transport properties of PVA membranes, taking into account radiation crosslinked PVA membranes, diffusive salt permeability through PVA membranes, and heat treated PVA membranes. The experimental findings support an occurrence of independent water, and salt permeation processes. It is suggested that the salt permeation is governed by a solution-diffusion transport mechanism. The preparation of thin skinned, asymmetric PVA membranes is also discussed. The employed method has a certain similarity to the classical phase inversion method, which is widely applied in the casting of asymmetric reverse osmosis membranes. Instead of using a gelling bath composed of a nonsolvent for the membrane material and miscible with the solvent from which the membrane is cast, a 'complexing' bath is used, which is a solution of a complexing agent in water.

  1. Electrospinning of poly(vinyl alcohol) nanofibers loaded with hexadecane nanodroplets.

    PubMed

    Arecchi, A; Mannino, S; Weiss, J

    2010-08-01

    The feasibility of producing poly(vinyl alcohol) (PVA) nanofibers containing fine-disperse hexadecane droplets by electrospinning a blend of hexadecane-in-water emulsions and PVA was investigated. Hexadecane oil-in-water nanoemulsions (d(10)= 181.2 +/- 0.1 nm) were mixed with PVA at pH 4.5 to yield polymer-emulsion blends containing 0.5 to 1.5 wt% oil droplets and 8-wt% PVA. The solution properties of emulsions and emulsion-PVA blends (viscosity, conductivity, surface tension) were determined. Solutions were electrospun and the morphology and thermal properties of deposited fiber mats characterized by scanning electron microscopy and differential scanning calorimetry. Fiber mats were dissolved in buffer to liberate incorporated hexadecane droplets and the buffer solutions analyzed by optical microscopy, UV-spectroscopy, and light scattering. Analysis of dry fiber mats and their solutions showed that emulsion droplets were indeed part of the electrospun fiber structures. Depending on the concentration of hexadecane in the initial emulsion-polymer blends, droplets were dispersed in the fibers as individual droplets or in form of aggregated flocs of hexadecane droplets. Nanofibers with spindle-like perturbations or nanofibers containing bead-like structures with approximately 5 times larger than the size of droplets in the original nanoemulsion were obtained. Remarkably, incorporation of hexadecane droplets in fibers did not alter size of individual droplets, that is, no coalescence occurred. The manufacture of solid matrix containing nanodroplets could be of substantial interest for manufacturers wishing to develop encapsulation system for lipophilic functional compounds such as lipid-soluble flavors, antimicrobials, antioxidants, and bioactives with tailored release kinetics. Practical Applications: The paper describes the formation of electrospun nanofibers from hydrophilic polymers that contain fine-disperse emulsion droplets. By incorporating emulsion droplets, a

  2. Isothermal Dendritic Growth Experiment - PVA Dendrites

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The Isothermal Dendritic Growth Experiment (IDGE), flown on three Space Shuttle missions, is yielding new insights into virtually all industrially relevant metal and alloy forming operations. IDGE used transparent organic liquids that form dendrites (treelike structures) similar to those inside metal alloys. Comparing Earth-based and space-based dendrite growth velocity, tip size and shape provides a better understanding of the fundamentals of dentritic growth, including gravity's effects. Shalowgraphic images of pivalic acid (PVA) dendrites forming from the melt show the subtle but distinct effects of gravity-driven heat convection on dentritic growth. In orbit, the dendrite grows as its latent heat is liberated by heat conduction. This yields a blunt dendrite tip. On Earth, heat is carried away by both conduction and gravity-driven convection. This yields a sharper dendrite tip. In addition, under terrestrial conditions, the sidebranches growing in the direction of gravity are augmented as gravity helps carry heat out of the way of the growing sidebranches as opposed to microgravity conditions where no augmentation takes place. IDGE was developed by Rensselaer Polytechnic Institute and NASA/Glenn Research Center. Advanced follow-on experiments are being developed for flight on the International Space Station. Photo Credit: NASA/Glenn Research Center

  3. The thermochemistry of solution of L-α-alanyl-L-α-alanine in water-alcohol mixtures at 298.15 K

    NASA Astrophysics Data System (ADS)

    Smirnov, V. I.; Badelin, V. G.

    2008-07-01

    The integral enthalpies of solution of L-α-alanyl-L-α-alanine in water-ethanol, water- n-propanol, and water-isopropanol mixtures were measured calorimetrically at alcohol concentrations x 2 ranging from 0 to 0.4 mole fractions. The standard enthalpy of peptide solution Δsol H o and transfer Δtr H o from water into a mixed solvent were calculated. The effect of the structure and properties of peptides and mixture composition on the enthalpy characteristics is discussed. The enthalpy coefficients of pair interactions h xy between L-α-alanyl-L-α-alanine and alcohol molecules were calculated; these coefficients were positive and increased in the series ethanol, n-propanol, isopropanol. The analysis performed allowed the differences in the thermodynamic characteristics of solution of L-α-alanyl-L-α-alanine and DL-α-alanyl-DL-α-alanine in water-alcohol mixtures to be determined.

  4. Composite Scaffold of Poly(Vinyl Alcohol) and Interfacial Polyelectrolyte Complexation Fibers for Controlled Biomolecule Delivery

    PubMed Central

    Cutiongco, Marie Francene A.; Choo, Royden K. T.; Shen, Nathaniel J. X.; Chua, Bryan M. X.; Sju, Ervi; Choo, Amanda W. L.; Le Visage, Catherine; Yim, Evelyn K. F.

    2015-01-01

    Controlled delivery of hydrophilic proteins is an important therapeutic strategy. However, widely used methods for protein delivery suffer from low incorporation efficiency and loss of bioactivity. The versatile interfacial polyelectrolyte complexation (IPC) fibers have the capacity for precise spatiotemporal release and protection of protein, growth factor, and cell bioactivity. Yet its weak mechanical properties limit its application and translation into a viable clinical solution. To overcome this limitation, IPC fibers can be incorporated into polymeric scaffolds such as the biocompatible poly(vinyl alcohol) hydrogel (PVA). Therefore, we explored the use of a composite scaffold of PVA and IPC fibers for controlled biomolecule release. We first observed that the permeability of biomolecules through PVA films were dependent on molecular weight. Next, IPC fibers were incorporated in between layers of PVA to produce PVA–IPC composite scaffolds with different IPC fiber orientation. The composite scaffold demonstrated excellent mechanical properties and efficient biomolecule incorporation. The rate of biomolecule release from PVA–IPC composite grafts exhibited dependence on molecular weight, with lysozyme showing near-linear release for 1 month. Angiogenic factors were also incorporated into the PVA–IPC grafts, as a potential biomedical application of the composite graft. While vascular endothelial growth factor only showed a maximum cumulative release of 3%, the smaller PEGylated-QK peptide showed maximum release of 33%. Notably, the released angiogenic biomolecules induced endothelial cell activity thus indicating retention of bioactivity. We also observed lack of significant macrophage response against PVA–IPC grafts in a rabbit model. Showing permeability, mechanical strength, precise temporal growth factor release, and bioinertness, PVA–IPC fibers composite scaffolds are excellent scaffolds for controlled biomolecule delivery in soft tissue

  5. An Examination of Problems and Solutions Related to the Chronic "Revolving Door" Alcohol Abuser. DHSS Planning Guideline #1, Task Assignment #1.11. Long-Term Support, Chronic Alcoholism and Other Drug Abuse.

    ERIC Educational Resources Information Center

    Vick, John W.; Houden, Dorothy

    This report contains recommendations of a Wisconsin Task Assignment Steering Committee created to explore solutions to some significant problems facing adult chronic "revolving-detox-door" alcohol abusers (CRA's), persons with repeated admissions for detoxification services; and to examine the system that serves and funds them. This report is…

  6. Adsorption of various alcohols on Illinois No. 6 coal in aqueous solutions

    SciTech Connect

    Kwon, K.C.; Rigby, R.R.

    1993-07-01

    Hydrophilicity, hydrophobicity and aromacity of Illinois {number_sign}6 coal in water are relatively determined by evaluating equilibrium physical/chemical adsorption of probe compounds on the coal. Experiments on equilibrium adsorption loadings of various additives on 60--200 mesh Illinois {number_sign}6 coal (DECS-2; Randolph county) were performed to investigate relatively surface properties of the coal at 25{degree}C. The additives include various alcohols, alkanes and aromatic compounds. The main objectives of this research are to evaluate relatively surface properties of raw coals, treated coals and coal minerals with the inverse liquid chromatography technique, using various probe compounds, to analyze flotation recoveries of coals with a micro-flotation apparatus in order to relate coal floatability to evaluated coal surface properties, and to delineate roles of coal-cleaning/handling additives with the inverse liquid chromatography technique.

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

    PubMed

    Zhou, Ling; He, Hui; Li, Mei-Chun; Song, Kunlin; Cheng, H N; Wu, Qinglin

    2016-11-20

    The present work describes the isolation of cellulose nanoparticles (CNs) with different morphologies and their influence on rheological properties of CN and CN-poly (vinyl alcohol) (PVA) suspensions. Cottonseed hulls were used for the first time to extract three types of CNs, including fibrous cellulose nanofibers, rod-like cellulose nanocrystals and spherical cellulose nanoparticles through mechanical and chemical methods. Rheology results showed that the rheological behavior of the CN suspensions was strongly dependent on CN concentration and particle morphology. For PVA/CN systems, concentration of PVA/CN suspension, morphology of CNs, and weight ratio of CN to PVA were three main factors that influenced their rheology behaviors. This research reveals the importance of CN morphology and composition concentration on the rheological properties of PVA/CN, providing new insight in preparing high performance hydrogels, fibers and films base on PVA/CN suspension systems. PMID:27561516

  8. Production of polyvinyl alcohol-degrading enzyme with Janthinobacterium sp. and its application in cotton fabric desizing.

    PubMed

    Du, Guocheng; Liu, Liming; Song, Zhaoxia; Hua, Zhaozhe; Zhu, Yang; Chen, Jian

    2007-06-01

    A strain capable of using polyvinyl alcohol (PVA) as sole carbon source was isolated from soil samples of a textile factory. The 16S rDNA sequence analysis cell morphology, physiology and biochemistry showed that it belonged to Janthinobacterium sp. This is the first report to show that the screened Janthinobacterium sp. could degrade PVA. The optimum nutritional and environmental conditions for PVA-degrading enzyme production by Janthinobacterium sp. were investigated by single-factor tests. Under optimized nutritional and environmental condition in shake flasks, PVA-degrading enzyme reached 5.12 U/mL at 21 h. With PVA-degrading enzyme produced by Janthinobacterium sp. WSH04-01, 80% of PVA could be degraded from cotton fabrics in 3 h. PMID:17345576

  9. Properties and Applications of Polyvinyl Alcohol, Halloysite Nanotubes and Their Nanocomposites.

    PubMed

    Gaaz, Tayser Sumer; Sulong, Abu Bakar; Akhtar, Majid Niaz; Kadhum, Abdul Amir H; Mohamad, Abu Bakar; Al-Amiery, Ahmed A

    2015-01-01

    The aim of this review was to analyze/investigate the synthesis, properties, and applications of polyvinyl alcohol-halloysite nanotubes (PVA-HNT), and their nanocomposites. Different polymers with versatile properties are attractive because of their introduction and potential uses in many fields. Synthetic polymers, such as PVA, natural polymers like alginate, starch, chitosan, or any material with these components have prominent status as important and degradable materials with biocompatibility properties. These materials have been developed in the 1980s and are remarkable because of their recyclability and consideration of the natural continuation of their physical and chemical properties. The fabrication of PVA-HNT nanocomposites can be a potential way to address some of PVA's limitations. Such nanocomposites have excellent mechanical properties and thermal stability. PVA-HNT nanocomposites have been reported earlier, but without proper HNT individualization and PVA modifications. The properties of PVA-HNT for medicinal and biomedical use are attracting an increasing amount of attention for medical applications, such as wound dressings, drug delivery, targeted-tissue transportation systems, and soft biomaterial implants. The demand for alternative polymeric medical devices has also increased substantially around the world. This paper reviews individualized HNT addition along with crosslinking of PVA for various biomedical applications that have been previously reported in literature, thereby showing the attainability, modification of characteristics, and goals underlying the blending process with PVA. PMID:26703542

  10. Embedded Ceria Nanoparticles in Crosslinked PVA Electrospun Nanofibers as Optical Sensors for Radicals.

    PubMed

    Shehata, Nader; Samir, Effat; Gaballah, Soha; Hamed, Aya; Elrasheedy, Asmaa

    2016-01-01

    This work presents a new nanocomposite of cerium oxide (ceria) nanoparticles embedded in electrospun PVA nanofibers for optical sensing of radicals in solutions. Our ceria nanoparticles are synthesized to have O-vacancies which are the receptors for the radicals extracted from peroxide in water solution. Ceria nanoparticles are embedded insitu in PVA solution and then formed as nanofibers using an electrospinning technique. The formed nanocomposite emits visible fluorescent emissions under 430 nm excitation, due to the active ceria nanoparticles with fluorescent Ce(3+) ionization states. When the formed nanocomposite is in contact with peroxide solution, the fluorescence emission intensity peak has been found to be reduced with increasing concentration of peroxide or the corresponding radicals through a fluorescence quenching mechanism. The fluorescence intensity peak is found to be reduced to more than 30% of its original value at a peroxide weight concentration up to 27%. This work could be helpful in further applications of radicals sensing using a solid mat through biomedical and environmental monitoring applications. PMID:27571083

  11. An experimental investigation of enzyme release from poly(vinyl alcohol) crosslinked microspheres.

    PubMed

    Bachtsi, A R; Kiparissides, C

    1995-01-01

    Crosslinked poly(vinyl alcohol) particles were prepared by the addition of glutaraldehyde into a PVA methanol/water solution in the presence of 0.2 N sulphuric acid. The polymer solution was dispersed in mineral oil in a jacketed vessel, with the aid of a six-blade impeller. Spherical crosslinked particles in the size range 30-80 microns were obtained by varying the degree of agitation or/and the amount of suspending agent. The crosslinked particles, after washing and drying, were placed into a protease enzyme solution for loading. The enzyme-containing water-swollen particles were subsequently removed from the solution and the enzyme release kinetics determined by a UV spectrophotometer. The influence of the degree of crosslinking, ionic strength, pH, particle size, and degree of hydrophilicity of the polymer on the enzyme activity was retained during the adsorption-desorption studies. The release behaviour of enzymes from crosslinked PVA particles exhibited a biphasic kinetic model, with an initial fast release followed by a much slower release rate. PMID:7730954

  12. Structure evolution and optimization in the fabrication of PVA-based activated carbon fibers.

    PubMed

    Zhang, Shu-Juan; Feng, Hui-Min; Wang, Jian-Ping; Yu, Han-Qing

    2008-05-01

    The structure and composition evolution of polyvinyl alcohol (PVA) fibers during the fabrication of activated carbon fibers (ACF) by a newly developed method were systematically elucidated. The pore structure of the fibers was significantly influenced by the carbonization and activation conditions. The elemental composition and chemical structure evolution of the fibers during the heat treatment processes were evaluated by elemental analysis, Fourier transform infrared spectrophotometry (FTIR), and X-ray photoelectron spectroscopy (XPS). Crystal structure evolution of the fibers during the heat treatment processes was elucidated by X-ray diffraction (XRD) analysis. Based on these understandings, the process conditions were optimized using an L(9)(3)(4) orthogonal array design matrix. Appropriate process parameters for the fabrication of PVA-ACFs were established as carbonizing the dehydrated fiber at 300 degrees C for 60 min, and then lifting the temperature to 900 degrees C with a heating speed of 10 degrees C/min in an inert atmosphere, thereafter keeping the fiber at 900 degrees C for 60 min in an oxidizing atmosphere. PMID:18261741

  13. Preparation and rheological studies of uncoated and PVA-coated magnetite nanofluid

    NASA Astrophysics Data System (ADS)

    Khosroshahi, M. E.; Ghazanfari, L.

    2012-12-01

    Experimental studies of rheological behavior of uncoated magnetite nanoparticles (MNPs)U and polyvinyl alcohol (PVA) coated magnetite nanoparticles (MNPs)C were performed. A Co-precipitation technique under N2 gas was used to prevent undesirable critical oxidation of Fe2+. The results showed that smaller particles can be synthesized in both cases by decreasing the NaOH concentration which in our case this corresponded to 35 nm and 7 nm using 0.9 M NaOH at 750 rpm for (MNPs)U and (MNPs)C. The stable magnetic fluid contained well-dispersed Fe3O4/PVA nanocomposites which indicated fast magnetic response. The rheological measurement of magnetic fluid indicated an apparent viscosity range (0.1-1.2) pa s at constant shear rate of 20 s-1 with a minimum value in the case of (MNPs)U at 0 T and a maximum value for (MNPs)C at 0.5 T. Also, as the shear rate increased from 20 s-1 to 150 s-1 at constant magnetic field, the apparent viscosity also decreased correspondingly. The water-based ferrofluid exhibited the non-Newtonian behavior of shear thinning under magnetic field.

  14. Thiazole yellow G dyed PVA films for optoelectronics: microstructrural, thermal and photophysical studies

    NASA Astrophysics Data System (ADS)

    Hebbar, Vidyashree; Bhajantri, R. F.; Naik, Jagadish; Rathod, Sunil G.

    2016-07-01

    In this paper, we report the microstructural, optical and fluorescence properties of poly(vinyl alcohol) (PVA)/Thiazole Yellow G (TY) dye composite prepared by solvent casting. The formation of change-transfer complex as a result of the interaction between the dye molecules and polymer chain is confirmed in FTIR, FT-Raman, XRD and DSC studies. SEM studies present the morphology of the samples. The UV-visible absorption spectra possess characteristic peaks of the TY dye corresponding to n-π* transition along with a characteristic peak of PVA. The composites exhibit the decreasing energy gap and increasing refractive index with an increase in wt.% of the TY dye. The fluorescence-quenching phenomena are observed in emission wavelength range of 391–406 nm upon excitation in the vicinity of absorption maxima (335 nm) with the quantum yield of 0.72 for lowest concentration of dye. The prepared composites bear high brightness, and improved thermal stability, which make them a promising material for sensors and optoelectronic applications.

  15. Electrical properties of irradiated PVA film by using ion/electron beam

    NASA Astrophysics Data System (ADS)

    Abdelrahman, M. M.; Osman, M.; Hashhash, A.

    2016-02-01

    Ion/electron beam bombardment has shown great potential for improving the surface properties of polymers. Low-energy charged (ion/electron) beam irradiation of polymers is a good technique to modify properties such as electrical conductivity, structural behavior, and their mechanical properties. This paper reports on the effect of nitrogen and electron beam irradiation on the electrical properties of polyvinyl alcohol (PVA) films. PVA films of 4 mm were exposed to a charged (ion/electron) beam for different treatment times (15, 30, and 60 minutes); the beam was produced from a dual beam source using nitrogen gas with the other ion/electron source parameters optimized. The dielectric loss tangent tan δ , electrical conductivity σ , and dielectric constant \\varepsilon ^' } in the frequency range 100 Hz-100 kHz were measured at room temperature. The variation of dielectric constant and loss tangent as a function of frequency was also studied at room temperature. The dielectric constant was found to be strongly dependent on frequency for both ion and electron beam irradiation doses. The real (\\varepsilon ^' }) and imaginary (\\varepsilon ^' ' }) parts of the dielectric constant decreased with frequency for all irradiated and non-irradiated samples. The AC conductivity showed an increase with frequency for all samples under the influence of both ion and electron irradiation for different times. Photoluminescence (PL) spectral changes were also studied. The formation of clusters and defects (which serve as non-radiative centers on the polymer surface) is confirmed by the decrease in the PL intensity.

  16. PVA bio-nanocomposites: a new take-off using cellulose nanocrystals and PLGA nanoparticles.

    PubMed

    Rescignano, N; Fortunati, E; Montesano, S; Emiliani, C; Kenny, J M; Martino, S; Armentano, I

    2014-01-01

    The formation of a new generation of hybrid bio-nanocomposites is reported: these are intended at modulating the mechanical, thermal and biocompatibility properties of the poly(vinyl alcohol) (PVA) by the combination of cellulose nanocrystals (CNC) and poly (D,L-lactide-co-glycolide) (PLGA) nanoparticles (NPs) loaded with bovine serum albumin fluorescein isothiocynate conjugate (FITC-BSA). CNC were synthesized from microcrystalline cellulose by hydrolysis, while PLGA nanoparticles were produced by a double emulsion with subsequent solvent evaporation. Firstly, binary bio-nanocomposites with different CNC amounts were developed in order to select the right content of CNC. Next, ternary PVA/CNC/NPs bio-nanocomposites were developed. The addition of CNC increased the elongation properties without compromising the other mechanical responses. Thermal analysis underlined the nucleation effect of the synergic presence of cellulose and nanoparticles. Remarkably, bio-nanocomposite films are suitable to vehiculate biopolymeric nanoparticles to adult bone marrow mesenchymal stem cells successfully, thus representing a new tool for drug delivery strategies. PMID:24274478

  17. Improvement of a Si solar cell efficiency using pure and Fe3+ doped PVA films

    NASA Astrophysics Data System (ADS)

    Khalifa, N.; Kaouach, H.; Chtourou, R.

    2015-07-01

    One of the most important key driving the economic viability of solar cells is the high efficiency. This research focuses on the enhancement of commercial Si solar cell performance by deposing a pure and Fe3+ doped polyvinyl alcohol (PVA) layer on the top of the Si wafer of the considered cells. The use of such polymer to improve solar cells efficiency is actually a first. The authors will rely on the optical characteristics of the pure and doped PVA films including absorption and emission properties to justify the effect on Si cells. Commercial monocrystalline silicon solar cells of 15 cm2 (0.49 V/460 mA) are used in this work. Films of almost 80 μm of the ferric polymer are deposed on the cells. Films with the same thickness are characterized by UV-Vis spectroscopy and photoluminescent emission of the films is then investigated. The electrical properties of the cells with and without the organometallic layer are evaluated. It will be deduced an important improvement of all electrical parameters, including short-circuit current, open-circuit voltage, fill factor and spatially the conversion efficiency by almost 3%.

  18. Electrical properties of irradiated PVA film by using ion/electron beam

    NASA Astrophysics Data System (ADS)

    Abdelrahman, M. M.; Osman, M.; Hashhash, A.

    2016-02-01

    Ion/electron beam bombardment has shown great potential for improving the surface properties of polymers. Low-energy charged (ion/electron) beam irradiation of polymers is a good technique to modify properties such as electrical conductivity, structural behavior, and their mechanical properties. This paper reports on the effect of nitrogen and electron beam irradiation on the electrical properties of polyvinyl alcohol (PVA) films. PVA films of 4 mm were exposed to a charged (ion/electron) beam for different treatment times (15, 30, and 60 minutes); the beam was produced from a dual beam source using nitrogen gas with the other ion/electron source parameters optimized. The dielectric loss tangent tan δ , electrical conductivity σ , and dielectric constant ɛ ^' } in the frequency range 100 Hz-100 kHz were measured at room temperature. The variation of dielectric constant and loss tangent as a function of frequency was also studied at room temperature. The dielectric constant was found to be strongly dependent on frequency for both ion and electron beam irradiation doses. The real (ɛ ^' }) and imaginary (ɛ ^' ' }) parts of the dielectric constant decreased with frequency for all irradiated and non-irradiated samples. The AC conductivity showed an increase with frequency for all samples under the influence of both ion and electron irradiation for different times. Photoluminescence (PL) spectral changes were also studied. The formation of clusters and defects (which serve as non-radiative centers on the polymer surface) is confirmed by the decrease in the PL intensity.

  19. Development, mechanical evaluation and surface characteristics of chitosan/polyvinyl alcohol based polymer composite coatings on titanium metal.

    PubMed

    Mishra, Sandeep K; Kannan, S

    2014-12-01

    Mechanical properties of orthopedic implants play important role in the regeneration and cell growth of the diseased body part. The present investigation was aimed at the development of a biocompatible, biodegradable and mechanically stable coating of chitosan (CS)-polyvinyl alcohol (PVA) polymer composite on Titanium (Ti) metal by employing a simple methodology at ambient conditions. The PVA to CS concentrations were maintained in fixed ratios of 1:4 weight/weight (w/w) for the development of all the coatings on Ti metal. Four different concentrations of the polymers ranging in the order of 5%, 10%, 15% and 20% weight/volume (w/v) solution of CS were selected in an aim to test their efficacy on mechanical stability. The results obtained from the analysis confirmed considerable improvement in mechanical properties of the composite polymer film comprising CS and PVA on Ti metal with the four different concentrations showing variable elastic modulus and hardness. The difference in mechanical properties of both dehydrated and hydrated coatings demonstrates the effective and efficient shielding of high mechanical properties of Ti metal in physiological conditions. The scratch tests performed on the coated specimens also indicated a good adhesion of the polymer on the Ti metal surface. PMID:25265031

  20. Amperometric catechol biosensor based on laccase immobilized on nitrogen-doped ordered mesoporous carbon (N-OMC)/PVA matrix

    NASA Astrophysics Data System (ADS)

    Guo, Meiqing; Wang, Hefeng; Huang, Di; Han, Zhijun; Li, Qiang; Wang, Xiaojun; Chen, Jing

    2014-06-01

    A functionalized nitrogen-containing ordered mesoporous carbon (N-OMC), which shows good electrical properties, was synthesized by the carbonization of polyaniline inside a SBA-15 mesoporous silica template. Based on this, through entrapping laccase onto the N-OMC/polyvinyl alcohol (PVA) film a facilely fabricated amperometric biosensor was developed. Laccase from Trametes versicolor was assembled on a composite film of a N-OMC/PVA modified Au electrode and the electrochemical behavior was investigated. The results indicated that the N-OMC modified electrode exhibits electrical properties towards catechol. The optimum experimental conditions of a biosensor for the detection of catechol were studied in detail. Under the optimal conditions, the sensitivity of the biosensor was 0.29 A*M-1 with a detection limit of 0.31 μM and a linear detection range from 0.39 μM to 8.98 μM for catechol. The calibration curve followed the Michaelis-Menten kinetics and the apparent Michaelis-Menten \\left( K_{M}^{app} \\right) was 6.28 μM. This work demonstrated that the N-OMC/PVA composite provides a suitable support for laccase immobilization and the construction of a biosensor.

  1. Encapsulation and immobilization of papain in electrospun nanofibrous membranes of PVA cross-linked with glutaraldehyde vapor.

    PubMed

    Moreno-Cortez, Iván E; Romero-García, Jorge; González-González, Virgilio; García-Gutierrez, Domingo I; Garza-Navarro, Marco A; Cruz-Silva, Rodolfo

    2015-01-01

    In this paper, papain enzyme (E.C. 3.4.22.2, 1.6 U/mg) was successfully immobilized in poly(vinyl alcohol) (PVA) nanofibers prepared by electrospinning. The morphology of the electrospun nanofibers was characterized by scanning electron microscopy (SEM) and the diameter distribution was in the range of 80 to 170 nm. The presence of the enzyme within the PVA nanofibers was confirmed by infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDXS) analyses. The maximum catalytic activity was reached when the enzyme loading was 13%. The immobilization of papain in the nanofiber membrane was achieved by chemical crosslinking with a glutaraldehyde vapor treatment (GAvt). The catalytic activity of the immobilized papain was 88% with respect to the free enzyme. The crosslinking time by GAvt to immobilize the enzyme onto the nanofiber mat was 24h, and the enzyme retained its catalytic activity after six cycles. The crosslinked samples maintained 40% of their initial activity after being stored for 14 days. PVA electrospun nanofibers are excellent matrices for the immobilization of enzymes due to their high surface area and their nanoporous structure. PMID:25953572

  2. MICROWAVE-ASSISTED SYNTHESIS OF CROSSLINKED POLY(VINYL ALCOHOL) NANOCOMPOSITES COMPRISING SINGLE-WALLED CARBON NANOTUBES, MULTI-WALLED CARBON NANOTUBES AND BUCKMINSTERFULLERENE

    EPA Science Inventory

    We report a facile method to accomplish cross-linking reaction of poly (vinyl alcohol) (PVA) with single-wall carbon nanotubes (SWNT), multi-wall carbon nanotubes (MWNT), and Buckminsterfullerene (C-60) using microwave (MW) irradiation. Nanocomposites of PVA cross-linked with SW...

  3. Alcoholism and Alcohol Abuse

    MedlinePlus

    ... This means that their drinking causes distress and harm. It includes alcoholism and alcohol abuse. Alcoholism, or ... brain, and other organs. Drinking during pregnancy can harm your baby. Alcohol also increases the risk of ...

  4. Diffraction efficiency improvement in high spatial frequency holographic gratings stored in PVA/AA photopolymers: several ACPA concentrations

    NASA Astrophysics Data System (ADS)

    Fernandez, Elena; Fuentes, Rosa; Ortuño, Manuel; Beléndez, Augusto; Pascual, Inmaculada

    2015-01-01

    High spatial frequency in holographic gratings is difficult to obtain due to limitations of the recording material. In this paper, the results obtained after storing holographic transmission gratings with a spatial frequency of 2656 lines/mm in a material based on polyvinyl alcohol and acrylamide (PVA/AA) are presented. A chain transfer agent, 4, 4‧-azobis (4-cyanopentanoic acid) (ACPA) was incorporated in the composition of the material to improve the response of the material at a high spatial frequency. Different concentrations of ACPA were used in order to find the optimal concentration giving maximum diffraction efficiency for high spatial frequencies.

  5. Preparation and characterization of antimicrobial wound dressings based on silver, gellan, PVA and borax.

    PubMed

    Cencetti, C; Bellini, D; Pavesio, A; Senigaglia, D; Passariello, C; Virga, A; Matricardi, P

    2012-10-15

    Silver-loaded dressings are designed to provide the same antimicrobial activity of topical silver, with the advantages of a sustained silver release and a reduced number of dressing changes. Moreover, such type of dressing must provide a moist environment, avoiding fiber shedding, dehydration and adherence to the wound site. Here we describe the preparation of a novel silver-loaded dressing based on a Gellan/Hyaff(®) (Ge-H) non woven, treated with a polyvinyl alcohol (PVA)/borax system capable to enhance the entrapment of silver in the dressing and to modulate its release. The new hydrophilic non woven dressings show enhanced water uptake capability and slow dehydration rates. A sustained silver release is also achieved. The antibacterial activity was confirmed on Staphylococcus aureus and Pseudomonas aeruginosa. PMID:22939352

  6. Fabrication of a New Type of Double-Shell Target Having a PVA Inner Layer

    SciTech Connect

    Steinman, D.A.; Wallace, R.; Grant, S.; Hoppe, M.C.; Smith, J.N. Jr.

    2004-03-15

    The General Atomics Target Fabrication team was tasked in FY03, under its ICF Target Support contract, to make a new type of double-shell target. Its specifications called for the outer shell to have an inner lining of PVA (poly(vinyl alcohol)) that would keep the xenon gas fill from occupying the target wall. The inner shell consisted of a glass shell coated with 2000 Angst of silver and filled with 9 atm of deuterium. Furthermore, the delivery deadline was less than seven weeks away. This paper describes the fielding of this double-shell target, made possible through the combined efforts of Lawrence Livermore National Laboratory and General Atomics target fabrication specialists.

  7. Immobilization of a Plant Lipase from Pachira aquatica in Alginate and Alginate/PVA Beads

    PubMed Central

    Bonine, Bárbara M.; Polizelli, Patricia Peres; Bonilla-Rodriguez, Gustavo O.

    2014-01-01

    This study reports the immobilization of a new lipase isolated from oleaginous seeds of Pachira aquatica, using beads of calcium alginate (Alg) and poly(vinyl alcohol) (PVA). We evaluated the morphology, number of cycles of reuse, optimum temperature, and temperature stability of both immobilization methods compared to the free enzyme. The immobilized enzymes were more stable than the free enzyme, keeping 60% of the original activity after 4 h at 50°C. The immobilized lipase was reused several times, with activity decreasing to approximately 50% after 5 cycles. Both the free and immobilized enzymes were found to be optimally active between 30 and 40°C. PMID:24818012

  8. FABRICATION OF A NEW TYPE OF DOUBLE SHELL TARGET HAVING A PVA INNER LAYER

    SciTech Connect

    STEINMAN,D.A; WALLACE,R; GRANT,S.E; HOPPE,M.L; SMITH,JR.J.N

    2003-06-01

    OAK-B135 The General Atomics Target Fabrication team was tasked in FY03, under its ICF Target Support contract, to make a new type of double-shell target. its specifications called for the outer shell to have an inner lining of PVA (poly(vinyl alcohol)) that would keep the xenon gas fill from occupying the target wall. The inner shell consisted of a glass shell coated with 2000 {angstrom} of silver and filled with 9 atm of deuterium. Furthermore, the delivery deadline was less than seven weeks away. This paper describes the fielding of this double-shell target, made possible through the combined efforts of Lawrence Livermore National Laboratory and General Atomics target fabrication specialists.

  9. Preparation and in vivo investigation of artificial cornea made of nano-hydroxyapatite/poly (vinyl alcohol) hydrogel composite.

    PubMed

    Fenglan, Xu; Yubao, Li; Xiaoming, Yao; Hongbing, Liao; Li, Zhang

    2007-04-01

    An artificial cornea consisted of a porous nano-hydroxyapatite/poly (vinyl alcohol) hydrogel (n-HA/PVA-H) skirt and a transparent center poly (vinyl alcohol) hydrogel (PVA-H) were prepared. The n-HA/PVA-H skirt was homogeneously porous and these pores were interconnected. Inter-penetrating network was observed along the interface between the core and the skirt. Artificial corneas were implanted in eyes of rabbit. The corneal tissues were evaluated histological. The results displayed that a good biocompatibility and interlocking had happened between artificial cornea and host tissues. This novel cornea prepared here is potential to be used clinically. PMID:17546425

  10. Effect of alcohol aggregation on the retention factors of chiral solutes with an amylose-based sorbent: modeling and implications for the adsorption mechanism.

    PubMed

    Tsui, Hung-Wei; Franses, Elias I; Wang, Nien-Hwa Linda

    2014-02-01

    Various displacement models in the literature have been widely used for understanding the adsorption mechanisms of solutes in various chromatography systems. The models were used for describing the often-observed linear plots of the logarithms of the retention factor versus the logarithms of the polar modifier concentration CI(0). The slopes of such a plot was inferred to be equal to the number of the displaced modifier molecules upon adsorption of one solute molecule, and were generally found to be greater than 1. In this study, the retention factors of four structurally related chiral solutes, ethyl lactate (EL), methyl mandelate (MM), benzoin (B), and pantolactone (PL), were measured for the amylose tris[(S)-α-methylbenzylcarbamate] sorbent, or AS, as a function of the concentration of isopropanol (IPA) in n-hexane. With increasing IPA concentration CI(0), the slopes increase from less than 1, at a concentration range from 0.13 to 1.3M, to slightly more than 1 at higher concentrations. Such slopes cannot be explained by the conventional retention models. It was found previously for monovalent solutes that such slopes can only be explained when the aggregation of the mobile phase modifier, isopropyl alcohol, was accounted for. A new retention model is presented here, accounting for alcohol aggregation, multivalent solute adsorption, multivalent solute-alcohol complexation, alcohol adsorption, and solute intra hydrogen-bonding, which occur in these four solutes. The slope is found to be controlled by three key dimensionless groups, the fraction of the sorbent binding sites covered by IPA, the fraction of the solute molecules in complex form, and the fraction of the IPA molecules in aggregate form. The limiting slope at a very high IPA concentration is equal to the value of (x+y)/n, where x is the number of the solute-sorbent binding sites and y is the number of the alcohol molecules in the solute-alcohol complex, and n is the alcohol aggregation number. The model

  11. Sulfidic photochemical passivation of GaAs surfaces in alcoholic solutions

    SciTech Connect

    Simonsmeier, T.; Ivankov, A.; Bauhofer, W.

    2005-04-15

    We report on a remarkable enhancement of the passivation effect of sulfidic solutions through illumination with above band gap light. Luminescence measurements on GaAs surfaces which have been illuminated during chemical passivation reveal in comparison to nonilluminated samples a further reduction of their surface density of states as well as a significantly increased stability of the passivation. Investigations with photoelectron spectroscopy show that illumination leads to a nearly complete removal of oxides on the surface. Measurements on Schottky diodes which have been manufactured with photochemically passivated GaAs indicate a noticeable decrease in band bending and a depinning of the Fermi level.

  12. Biodegradable poly(ethylene-g-vinyl alcohol) copolymer

    SciTech Connect

    Watanabe, T.; Huang, S.J.

    1993-12-31

    A graft reaction of poly(vinyl alcohol), PVA, and polyethylene grafted width maleic anhydride has been carried out in order to add hydrophobicity to PVA. Biodegradabilities of PVA and the polyethylene derivative are well-known. The graft reaction product that was prepared by a simple procedure was characterized with FTIR, DSC, and TGA. The FTIR spectra indicated that ester bonds were formed in the product. It was also found from the thermal analysis that the graft compound was less crystalline that raw PVA and the thermal properties of the graft copolymer remarkably depended on molar ratio of succinic anhydride group in the polyethylene derivative that was used in the graft reaction. The degradation of the material will be discussed.

  13. Micropatterning of silver nanoclusters embedded in polyvinyl alcohol films.

    PubMed

    Karimi, Nazanin; Kunwar, Puskal; Hassinen, Jukka; Ras, Robin H A; Toivonen, Juha

    2016-08-01

    Direct laser writing has been utilized to fabricate highly photostable fluorescent nanocluster microstructures in an organic polymer poly(methacrylic acid), where the carboxyl functional group is reported to play a vital role in nanocluster stabilization. In this Letter, we demonstrate that not only the polymer containing the carboxyl functional group, but also the polymer comprising the hydroxyl group, namely polyvinyl alcohol (PVA), can act as an appropriate stabilizer matrix for laser-induced synthesis and patterning of silver nanoclusters. The as-formed nanoclusters in the PVA film exhibit broadband emission and photostability comparable to the nanoclusters formed in the poly(methacrylic acid) polymer. As PVA is a widely used, nontoxic, biocompatible and biodegradable polymer, the technique of patterning fluorescent nanoclusters in PVA thin films is expected to find numerous applications in fields like fluorescence imaging, biolabeling, and sensing. PMID:27472635

  14. Linear and nonlinear optical properties of nanostructured Zn(1-x)SrxO-PVA composite thin films

    NASA Astrophysics Data System (ADS)

    Tamgadge, Y. S.; Sunatkari, A. L.; Talwatkar, S. S.; Pahurkar, V. G.; Muley, G. G.

    2014-11-01

    We investigate the effect of strontium doping on the linear and third order nonlinear optical properties of ZnO-polyvinyl alcohol (PVA) nano-composite thin films. Strontium doped ZnO nanoparticles capped with L-arginine were synthesized by low cost soft chemical route. These nanoparticles were characterized by X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy for its crystal structure and surface morphology studies. Linear optical responses of these samples were studied by using ultraviolet-visible (UV-vis) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Presence of excitonic peaks for doped and undoped ZnO was revealed by UV-vis data and shift of excitonic peaks towards lower energy with increase in dopant concentration was observed. Rotational and vibrational signatures of capping agent and ZnO were confirmed by FT-IR spectroscopy. Third order nonlinearity (nonlinear refraction and absorption) of Zn(1-x)SrxO-PVA thin films, deposited on the good optical quality glass substrate, were studied by z-scan technique using He-Ne laser (wavelength 632.8 nm) in continuous wavelength regime which shows negative nonlinearity with self-defocusing effect. The large value of n2 (10-4 cm2/W) is obtained for 5 wt% strontium doped ZnO-PVA thin film and is attributed to the thermal effect. Enhanced nonlinear absorption due to reverse saturable absorption and weak free carrier absorption is observed for all undoped and doped ZnO-PVA thin films and is prominent for 5 wt% doping of strontium. Third order nonlinear susceptibility χeff(3) is calculated for all samples.

  15. Comparison of porous poly (vinyl alcohol)/hydroxyapatite composite cryogels and cryogels immobilized on poly (vinyl alcohol) and polyurethane foams for removal of cadmium.

    PubMed

    Wang, Xiao; Min, Byung Gil

    2008-08-15

    Three novel adsorbents of hydroxyapatite/poly (vinyl alcohol) (HAp/PVA) cryogel, HAp/PVA cryogel immobilized on PVA foam and HAp/PVA cryogel immobilized on polyurethane (PU) foam have been investigated to compare the morphology and sorption performances for removal of cadmium. The adsorption kinetics was interpreted by double-exponential model, pseudo-first-order model and pseudo-second-order models. The equilibrium time was found to be 36, 24, and 12 h for cryogel, cryogel immobilized on PVA foam and PU foam, respectively. The adsorption was found to follow Langmuir isotherm model and the maximum sorption capacity was estimated to be 53.3, 53.1 and 47.7 mg g(-1) for cryogel, cryogel immobilized on PVA foam and PU foam. The effects of HAp/PVA ratio and drying method on cadmium sorption were also studied. The difference of adsorption kinetics model and equilibrium time among the three adsorbents was suggested to be ascribed to different pore size. Oven-dried HAp/PVA cryogel immobilized on PU foam was preferable due to short equilibrium time and good sorption ability. PMID:18262348

  16. Enhanced mechanical properties and morphological characterizations of poly(vinyl alcohol) carbon nanotube composite films

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Tao, Xiaoming; Xue, Pu; Cheng, Xiaoyin

    2005-12-01

    Tensile tests were carried out on free-standing composite films of poly(vinyl alcohol) (PVA) and multiwall carbon nanotubes (MWNTs) for different loading levels. Results show that overall mechanical properties of the composite were greatly improved as compared to the neat PVA film. For PVA-based materials at significant high loading level such as 9.1 wt.% MWNTs, considerable increases in Young's modulus, tensile strength and toughness by factors of 4.5, 2.7 and 4.1, respectively, were achieved. Raman, SEM, TEM, and DSC techniques were used to evaluate the PVA/MWNTs composite system. Strong acid-modification of the pristine MWNTs and the subsequent ultrasonication processing allowed good distribution of the nanotubes in the matrix. SEM together with DSC result shows apparent good wetting of the nanotubes by the PVA matrix, which are supportive of good interfacial bonding between the modified carbon nanotubes and the hosting polymer matrix.

  17. Poly(vinyl alcohol) physical hydrogels: new vista on a long serving biomaterial.

    PubMed

    Alves, Marie-Helene; Jensen, Bettina E B; Smith, Anton A A; Zelikin, Alexander N

    2011-10-10

    Poly(vinyl alcohol), PVA, and physical hydrogels derived thereof have an excellent safety profile and a successful history of biomedical applications. However, these materials are hardly in the focus of biomedical research, largely due to poor opportunities in nano- and micro-scale design associated with PVA hydrogels in their current form. In this review we aim to demonstrate that with PVA, a (sub)molecular control over polymer chemistry translates into fine-tuned supramolecular association of chains and this, in turn, defines macroscopic properties of the material. This nano- to micro- to macro- translation of control is unique for PVA and can now be accomplished using modern tools of macromolecular design. We believe that this strategy affords functionalized PVA physical hydrogels which meet the demands of modern nanobiotechnology and have a potential to become an indispensable tool in the design of biomaterials. PMID:21793217

  18. Enhanced selectivity for the electrochemical reduction of CO2 to alcohols in aqueous solution with nanostructured Cu-Au alloy as catalyst

    NASA Astrophysics Data System (ADS)

    Jia, Falong; Yu, Xinxing; Zhang, Lizhi

    2014-04-01

    Electrochemical reduction of CO2 in an aqueous 0.5 M KHCO3 solution is studied by use of novel nanostructured Cu-Au alloys, which are prepared through electrochemical deposition with a nanoporous Cu film (NCF) as template. Linear voltammetry results show that the as-synthesized Cu-Au alloys exhibit obvious catalysis towards electrochemical reduction of CO2. Further analysis of products reveals that faradic efficiencies of alcohols (methanol and ethanol) are greatly dependent on the nanostructures and compositions of Cu-Au alloys. It is expected that this work could provide new insight into the development of powerful electrocatalysts for reduction of CO2 to alcohols.

  19. The thermochemical characteristics of solution of DL-α-alanylglycine and DL-α-alanylalanine in water-alcohol mixtures at 298.15 K

    NASA Astrophysics Data System (ADS)

    Smirnov, V. I.; Mezhevoi, I. N.; Badelin, V. G.

    2007-05-01

    The integral enthalpies of solution of DL-α-alanylglycine and DL-α-alanylalanine in water-ethanol, water-n-propanol, and water-isopropanol mixtures were measured calorimetrically at alcohol concentrations x 2 = 0-0.4 mole fractions. The standard enthalpies of solution (Δsol H°) of the peptides and their transfer (Δtr H°) from water into the mixed solvents were calculated. The influence of the structure and properties of the solutes and mixture composition on the enthalpy characteristics were considered. The Δsol H° = f(x 2) and Δtr H° = f(x 2) dependences were found to have extrema. The enthalpy coefficients of pair interactions (h xy ) between the peptide and alcohol molecules were calculated. The coefficients were positive and increased in the series ethanol, n-propanol, isopropanol.

  20. Evaluation of cellulose and carboxymethyl cellulose/poly(vinyl alcohol) membranes.

    PubMed

    Ibrahim, Maha M; Koschella, Andreas; Kadry, Ghada; Heinze, Thomas

    2013-06-01

    Cellulose was isolated from rice straw and converted to carboxymethyl cellulose (CMC). Both polymers were crosslinked with poly(vinyl alcholo) (PVA). The physical properties of the resulting membranes were characterized by FT-IR, TGA, DSC and SEM. The cellulose and CMC were first prepared from bleached rice straw pulp. The infrared spectroscopy of the resulting polymer membranes indicated a decrease in the absorbance of the OH group at 3300-3400 cm(-1), which is due to bond formation with either the cellulose or CMC with the PVA. The thermal stability of PVA/cellulose and PVA/CMC membranes was lower than PVA membrane. The surface of the resulting polymer membranes showed smooth surface in case of the PVA/CMC membrane and rough surface in case of the PVA/cellulose membrane. Desalination test, using 0.2% NaCl, showed that pure PVA membranes had no effect while membranes containing either cellulose or CMC as filler were able to decrease the content of the NaCl from the solution by 25% and 15%, respectively. Transport properties, including water and chloroform vapor were studied. The moisture transport was reduced by the presence of both cellulose and CMC. Moreover, the membranes containing cellulose and CMC showed significantly reduced flux compared to the pure PVA. The water sorption, solubility and soaking period at different pH solutions were also studied and showed that the presence of both cellulose and CMC influences the properties. PMID:23618287

  1. Non-cytotoxic silver nanoparticle-polyvinyl alcohol hydrogels with anti-biofilm activity: designed as coatings for endotracheal tube materials.

    PubMed

    Loo, Ching-Yee; Young, Paul M; Lee, Wing-Hin; Cavaliere, Rosalia; Whitchurch, Cynthia B; Rohanizadeh, Ramin

    2014-01-01

    Endotracheal intubation is commonly associated with hospital-acquired infections as the intubation device acts as reservoir for bacterial colonization in the lungs. To reduce the incidence of bacterial colonization on the tubes, hydrogel coatings loaded with antimicrobial agents are gaining popularity. The aim of this study was to incorporate silver nanoparticles (AgNPs) into polyvinyl alcohol (PVA) to form stable hydrogels. Embedding AgNPs into PVA resulted in a decreased elongation at break and an increased tensile strength compared to PVA alone. The Ag release profile varied as a function of the degree of hydrolysis of PVA: the higher degree of hydrolysis demonstrated a lower release rate. Fourier infrared transform spectroscopy demonstrated that AgNPs interacted exclusively with the -OH groups of PVA. AgNP-loaded PVA was non-toxic against human normal bronchial epithelial cells while effective against the attachment of Pseudomonas aeruginosa and Staphylococcus aureus with a greater effect on P. aeruginosa. PMID:24963686

  2. Effect of Cross-Linking on the Mechanical and Thermal Properties of Poly(amidoamine) Dendrimer/Poly(vinyl alcohol) Hybrid Membranes for CO2 Separation

    PubMed Central

    Duan, Shuhong; Kai, Teruhiko; Saito, Takashi; Yamazaki, Kota; Ikeda, Kenichi

    2014-01-01

    Poly(amidoamine) (PAMAM) dendrimers were incorporated into cross-linked poly(vinyl alcohol) (PVA) matrix to improve carbon dioxide (CO2) separation performance at elevated pressures. In our previous studies, PAMAM/PVA hybrid membranes showed high CO2 separation properties from CO2/H2 mixed gases. In this study, three types of organic Ti metal compounds were selected as PVA cross-linkers that were used to prepare PAMAM/cross-linked PVA hybrid membranes. Characterization of the PAMAM/cross-linked PVA hybrid membranes was conducted using nanoindentation and thermogravimetric analyses. The effects of the cross-linker and CO2 partial pressure in the feed gas on CO2 separation performance were discussed. H2O and CO2 sorption of the PAMAM/PVA hybrid membranes were investigated to explain the obtained CO2 separation efficiencies. PMID:24957172

  3. CO2 adsorption properties of char produced from brown coal impregnated with alcohol amine solutions.

    PubMed

    Baran, Paweł; Zarębska, Katarzyna; Czuma, Natalia

    2016-07-01

    Carbon dioxide (CO2) emission reduction is critical to mitigating climate change. Power plants for heating and industry are significant sources of CO2 emissions. There is a need for identifying and developing new, efficient methods to reduce CO2 emissions. One of the methods used is flue gas purification by CO2 capture through adsorption. This study aimed to develop CO2 adsorbent out of modified brown coal impregnated with solutions of first-, second-, and third-order amines. Low-temperature nitrogen adsorption isotherms and CO2 isotherms were measured for the prepared samples. The results of experiments unexpectedly revealed that CO2 sorption capacity decreased after impregnation. Due to lack of strait trends in CO2 sorption capacity decrease, the results were closely analyzed to find the reason for the inconsistencies. It was revealed that different amines represent different affinities for CO2 and that the size and structure of impregnating factor has influence on the CO2 sorption capacity of impregnated material. The character of a support was also noticeable as well for impregnation results as for the affinity to CO2. The influence of amine concentration used was investigated along with the comparison on how the theoretical percentage of the impregnation on the support influenced the results. The reaction mechanism of tertiary amine was taken into consideration in connection to no presence of water vapor during the experiments. Key findings were described in the work and provide a strong basis for further studies on CO2 adsorption on amine-impregnated support. PMID:27317051

  4. Importance of solute partitioning in biphasic oxidation of benzyl alcohol by free and immobilized whole cells of Pichia pastoris

    SciTech Connect

    Kawakami, Koei; Nakahara, Takehiko . Dept. of Chemical Engineering)

    1994-04-25

    Using free and immobilized whole cells of Pichia pastoris, the biocatalytic oxidation of benzyl alcohol was investigated in different two-phase systems. This reaction was strongly influenced by both the substrate and product inhibitions, and the production rate of benzaldehyde in the aqueous system became maximum at the initial substrate concentration of ca. 29 g/L with the aldehyde formation less than 4 to 5 g/L even after a longer reaction period. The reaction rates in the two-liquid phase systems were predominantly determined by the partitioning behaviors of the substrate and the product between the two phases rather than by enzyme deactivation by the organic solvents. In the two-liquid phase systems, consequently, the organic solvent acted as a reservoir to reduce these inhibitory effects, and it was essential to select the organic solvent providing the optimal partitioning of the substrate into the aqueous phase as well as the preferential extraction of the product into the organic phase. The whole cells immobilized in a mixed matrix composed of silicone polymer and Ca alginate gel worked well in the xylene and decane media, providing comparable activities with the free cells. The production rate of aldehyde was also influenced by the solute partitioning into the hydrophilic alginate phase where the cells existed.

  5. A new selective fluorene-based fluorescent internal charge transfer (ICT) sensor for sugar alcohols in aqueous solution.

    PubMed

    Hosseinzadeh, Rahman; Mohadjerani, Maryam; Pooryousef, Mona

    2016-03-01

    Sugar alcohols, such as sorbitol, are commonly used as a replacement for sucrose in the food industry, applied as starting material for vitamin C synthesis, and involved as one of the causative factors in diabetic complications. Therefore, their detection and quantification in aqueous solution are necessary. The reversible covalent interactions between boronic acids and diols are the basis of efficient methods for the detection of saccharides. Herein, we report a new internal charge transfer (ICT) fluorene-based fluorescent boronic acid sensor (1) 2-[(9,9-dimethyl-9H-fluoren-2-yl-amino)methyl] phenyl boronic acid that shows significant fluorescence changes upon addition of saccharides. The boronic acid has high affinity (K a = 1107.9 M(-1)) and selectivity for sorbitol at pH = 8.31. It showed a linear response toward sorbitol in the concentration range from 1.0 × 10(-5) to 6.0 × 10(-4) mol L(-1) with the detection limit of 7.04 × 10(-6) mol L(-1). Sensor 1 was used to detect sorbitol in real samples with good recovery. PMID:26758597

  6. Remediation of environmental pollution by substituting poly(vinyl alcohol) with biodegradable warp size from wheat gluten.

    PubMed

    Chen, Lihong; Reddy, Narendra; Yang, Yiqi

    2013-05-01

    We report the development of wheat gluten as an environmentally friendly sizing agent that can replace poly(vinyl alcohol) (PVA) and make the textile industry more environmentally friendly. Wheat gluten applied onto polyester/cotton (P/C) and polyester as warp sizing agent provided sizing performance and biodegradability in activated sludge necessary to substitute poly(vinyl alcohol) (PVA). PVA is one of the most widely used sizing agents and provides excellent sizing performance to synthetic fibers and their blends but is expensive and difficult to degrade in textile wastewater treatment plants. Although considerable efforts have been made to replace PVA, it has not been possible to develop a warp sizing chemical that can match the sizing performance of PVA and at the same time be cost-effective and biodegrade in effluent treatment plants. At similar % add-on, wheat gluten provided similar cohesion to P/C but much higher abrasion resistance to polyester fabrics compared to PVA. With a biochemical oxygen demand (BOD) to chemical oxygen demand (COD) ratio of 0.7 compared to 0.01 for PVA, wheat gluten was readily degradable in activated sludge. Wheat gluten has the ability to replace PVA for textile warp sizing applications. PMID:23551198

  7. An intensive study on the optical, rheological, and electrokinetic properties of polyvinyl alcohol-capped nanogold

    NASA Astrophysics Data System (ADS)

    Behera, Manoranjan

    2015-05-01

    Low-temperature-assisted wet chemical synthesis of nanogold (NG) using gold hydroxide, a new precursor salt in the presence of a macroscopic ligand poly(vinyl alcohol) PVA in water in the form of nanofluid, is reported for the first time in this article. In the absorption spectra, the surface Plasmon resonance absorption band in the range of 520-545 nm signifies the formation of NG via a controlled Au3+ + 3e → Au reaction grafted in small assemblies with polymer. Absorption maximum increases nonlinearly with Au-contents up to 100 µM Au in Au-PVA charge-transfer complex. Marked enhancement in the peak intensity of some of the vibration bands of PVA polymer such as C-H stretching, C=O stretching, CH2 bending, and C-C in-plane bending in the presence of NG reveals an interfacial interaction between NG and oxidized PVA via C=O group. Execution of shear thinning behavior regardless of the Au-content strongly suggests that crosslinking exists between NG and PVA in Au-PVA rheo-optical nanofluids. Hydrodynamic diameter and polydispersity index draw a nonlinear path with the Au doping with 30.0 g/L PVA in water over a wide region of 5-100 μM Au covered in this study. Enhancement in the zetapotential of Au-PVA nanofluid over bare PVA in water is ascribed to buildup of nonbonding electrons of "-C=O" moieties from the oxidized PVA on the NG surface. Displaying of lattice fringes in the microscopic image of core-shell Au-PVA nanostructure confirms that crystalline nature of NG core with inter planar spacing 0.235 nm corresponds to Au (111) plane.

  8. An experimental study for syndiotactic polyvinyl alcohol spheres as an embolic agent: can it maintain spherical shape in vivo?

    PubMed

    Chun, Ho Jong; Lee, Hae Giu; Lyoo, Won Seok; Lee, Ji Youl; Kim, Jina

    2014-01-01

    Syndiotactic polyvinyl alcohol (PVA) had been developed to overcome the drawbacks of atactic PVA spheres that deform easily, which can lead to non-target embolization. This study was performed to evaluate the in vivo stability of spherical shape of the syndiotactic PVA spheres. Selective arteriography and transarterial embolization (TAE) were performed in the main renal arteries of eight New Zealand white rabbits using syndiotactic PVA sphere that consisted of syndiotactic PVA skin and a copolymer core of vinyl acetate/vinyl pivalate. The size of the syndiotactic PVA spheres used for the TAE was 212-355 μm. The rabbits were sacrificed 12-14 days after TAE. Gross and microscopic examinations of each kidney were performed. The microscopic examination showed infarction of all embolized kidneys. Syndiotactic PVA spheres were seen uniformly within the arterial lumen and appeared as round ring-like structures without any deformity. The syndiotactic PVA spheres exclusively occupied the arterial lumen. As a conclusion, syndiotactic PVA spheres maintained their spherical shape without significant deformation in this in vivo short-term experimental study. Further investigation is necessary for evaluation of detailed effects of physical stability in tumor embolization. PMID:24948458

  9. Plasma functionalization of poly(vinyl alcohol) hydrogel for cell adhesion enhancement

    PubMed Central

    Ino, Julia M.; Chevallier, Pascale; Letourneur, Didier; Mantovani, Diego; Le Visage, Catherine

    2013-01-01

    Tailoring the interface interactions between a biomaterial and the surrounding tissue is a capital aspect to consider for the design of medical devices. Poly(vinyl alcohol) (PVA) hydrogels present suitable mechanical properties for various biological substitutes, however the lack of cell adhesion on their surface is often a problem. The common approach is to incorporate biomolecules, either by blending or coupling. But these modifications disrupt PVA intra- and intermolecular interactions leading therefore to a loss of its original mechanical properties. In this work, surface modification by glow discharge plasma, technique known to modify only the surface without altering the bulk properties, has been investigated to promote cell attachment on PVA substrates. N2/H2 microwave plasma treatment has been performed, and the chemical composition of PVA surface has been investigated. X-ray photoelectron and Fourier transform infrared analyses on the plasma-treated films revealed the presence of carbonyl and nitrogen species, including amine and amide groups, while the main structure of PVA was unchanged. Plasma modification induced an increase in the PVA surface wettability with no significant change in surface roughness. In contrast to untreated PVA, plasma-modified films allowed successful culture of mouse fibroblasts and human endothelial cells. These results evidenced that the grafting was stable after rehydration and that it displayed cell adhesive properties. Thus plasma amination of PVA is a promising approach to improve cell behavior on contact with synthetic hydrogels for tissue engineering. PMID:23989063

  10. Preparation and Properties of Nano-Hydroxyapatite/Gelatin/Poly(vinyl alcohol) Composite Membrane.

    PubMed

    Liao, Haotian; Shi, Kun; Peng, Jinrong; Qu, Ying; Liao, Jinfeng; Qian, Zhiyong

    2015-06-01

    In this study, the bone-like composite membrane based on blends of gelatin (Gel), nano-hydroxyapatite (n-HA) and poly(vinyl alcohol) (PVA) was fabricated by solvent casting and evaporation methods. The effect of n-HA content and the ratio of Gel/PVA on the properties of the composite was investigated. The Gel/PVA and n-HA/Gel/PVA composite membranes were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), water contact angle measurement and scanning electron microscopy (SEM). The mechanical properties of the composites were determined by tensile tests. The as prepared composite membranes exhibited hydrophobility, the water contact angle of composite membrane was 126.6 when its mass ratio of n-HA/Gel/PVA was 10/50/40. The tensile strength of composite membranes was greatly increased due to the introduction of n-HA, and the tensile strength was increased to 74.92 MPa when the mass ratio of n-HA/Gel/PVA was 10/50/40. SEM observation indicated that n-HA was dispersed in the membranes and a sea-island structure was formed in the n-HA/Gel/PVA composite membranes, resulting in a significant increase in tensile strength. The as-prepared n-HA/Gel/PVA composite membranes may be applied in the field of bone tissue engineering. PMID:26369028

  11. Evaluation of the effect of V2O5 on the electrical and thermoelectric properties of poly(vinyl alcohol)/graphene nanoplatelets nanocomposite

    NASA Astrophysics Data System (ADS)

    Morad, M.; Fadlallah, M. M.; Hassan, M. A.; Sheha, E.

    2016-03-01

    The aim of this contribution is to introduce high performance materials for thermoelectric devices. A nanopolymer composite of PVAGNP ((polyvinyl alcohol ((PVA)0.6/graphene nanoplatelets (GNP)0.4))1-x(V2O5)x where x = 0, 2.5, 5, 7.5 and 10 wt% has been prepared using a solution cast technique. The influence of V2O5 additives on the morphology, structure, thermal and electrical properties of PVA has been examined by FTIR, XRD, TGA, DC and IV techniques. The disassociation of V2O5 to (V4+) and (V5+) in the composites acts as a co-bridge which can facilitate the translational electronic motion, which enhances the charge carrier mobility and the electrical conductivity. A prototype cell was constructed using (PVAGNP)1-x(GNP)x nanocomposites with constantan wire. The addition of V2O5 improves the thermoelectric properties of the (PVA)0.6(GNP)0.4 nanocomposite, where the Seebeck coefficient is increased from 23.1 to 45.8 μV K-1 from 0 to 10 wt% V2O5, respectively. The power factor is increased from 1.17 × 10-2 to 36.30 × 10-2 μWm-1 K-2 from 0 to 10 wt% V2O5, respectively, and the ZT is increased from 4.47 × 10-9 to 1.46 × 10-7.

  12. Sol-gel synthesis and characterization of nanocrystalline (Bi0.5Na0.5)TiO3 powders from the poly vinyl alcohol evaporation route

    NASA Astrophysics Data System (ADS)

    Haitao, Liu; xiaohui, Wang; Longtu, Li

    2009-09-01

    Nanocrystalline pure perovskite phase bismuth sodium titanate (Bi0.5Na0.5)TiO3(BNT) powders have been prepared by a sol-gel method from the poly vinyl alcohol evaporation route, bismuth nitrate [Bi(NO3)3], tetra-butyl titanate [Ti(OC4H9)4] and sodium acetate(CH3COONa) were used as raw materials and poly vinyl alcohol(PVA) as the sol-gel forming solvent. Stoichiometric amounts of the individual raw materials were thoroughly mixed in accordance with the BNT composition to form the stock solution. The pH of the stock was adjusted to 1-3 by adding acetate. Aqueous solution of PVA[10%(w/v)] was then added to the cationic mixture with thorough stirring. The weight ratio of the cationic mixture to the PVA aqueous solution was maintained at 2:1. The resulting viscous liquid was then heated over a hot crucible up to form a fluffy dry gel. The fluffy dry gels were calcined at different temperatures and times and then cooled to room temperature naturally. The X-ray powder diffraction(XRD) patterns of the heat-treated powders were obtained using a Bruker D8 Advance X-ray diffractometer with Cu Kα radiation and nickel filter. Scanning electron microscope (SEM) studies of the NBT powders were performed using a JSM-6700F electron microscope. Phase-pure BNT powders were obtained at 550°C for 2-2.5h which is relatively lower calcination temperature than other reports. The BNT powders consists of phase-pure perovskite nanocrystals with an average size of 100-200nm.

  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. PMID:27037828

  14. Structural analysis, and antioxidant and antibacterial properties of chitosan-poly (vinyl alcohol) biodegradable films.

    PubMed

    Hajji, Sawssen; Chaker, Achraf; Jridi, Mourad; Maalej, Hana; Jellouli, Kemel; Boufi, Sami; Nasri, Moncef

    2016-08-01

    The development and characterization of biodegradable blend films based on chitosan and poly (vinyl alcohol) for possible use in a variety of biological activities are reported. Fourier transform infrared spectroscopy (FTIR) spectra of chitosan-poly (vinyl alcohol) (Ch/PVA) films showed characteristics peaks shifting to a lower frequency range due to hydrogen bonding between -OH of PVA and -NH2 of chitosan. The chitosan and PVA polymers presented good compatibility. The morphology study of chitosan and composite films showed a compact and homogenous structure. The tensile strength and elongation at break increased with PVA content. In fact, the highest tensile strength and elongation at break (53.58 MPa and 454 %) occurs with pure PVA film. The results showed that PVA incorporation in the blends contributes to increase the intermolecular interactions, thus improving the mechanical properties. In addition, the prepared films demonstrated high antioxidant activities monitored by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging, reducing power, and β-carotene bleaching activity. Nevertheless, PVA addition reduced antioxidant and antibacterial activities against Gram-positive and Gram-negative bacteria tested. PMID:27106077

  15. Two-dimensional numerical simulation of the red blood cell floating in a plasma-alcohol solution through stenosis in a microvessel

    NASA Astrophysics Data System (ADS)

    Ni, Aleksey; Cheema, Taqi Ahmad; Kwak, Moon Kyu; Park, Cheol Woo

    2014-08-01

    A two-dimensional computational model of a single red blood cell (RBC) floating in a plasma-alcohol solution through a microchannel with stenosis was created using the Arbitrary Lagrangian-Eulerian (ALE) method with moving mesh for a fluid structure interaction problem. Cell deformability and stability were studied in a plasma-alcohol solution at different fluid flow conditions during movement through the channel with stenosis. Different results were obtained for different input parameters. Motion through 45% and 70% stenoses with the high and law velocities of the RBC and different viscosities was analyzed and successfully simulated. Results show that changes in RBC deformability were due to the effects of alcohol. Changes in behavior during motion were also observed. At low shear rate and high surrounding fluid viscosity the RBC showed a tendency to rotate during movement. The proposed model with its coupling of structural and fluid analysis techniques could be useful to understand the effect of alcohol on the RBC passing through stenosis.

  16. 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.

  17. 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.

  18. Molecular vibrational dynamics in polyvinyl alcohol studied by femtosecond coherent anti-stokes Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kozai, T.; Yamashita, S.; Hirochi, K.; Miyagawa, H.; Tsurumachi, N.; Koshiba, S.; Nakanishi, S.; Itoh, H.

    2012-11-01

    We have performed femtosecond time-resolved coherent anti-stokes Raman spectroscopy (CARS) to study the vibrational dynamics in polyvinyl alcohol (PVA) film. We observed femtosecond coherent vibrational relaxation and CARS signal beats in PVA at room temperature. We found that the coherent vibrational relaxation of anti-symmetric CH2 stretching modes in PVA is faster than that of symmetric modes, probably due to faster vibrational energy transfer. The coherent vibrational relaxation of OH stretching modes was observed to be slower than that of CH2 modes, because OH stretching modes have less resonant energy transfer rate compared to CH2 modes.

  19. 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).

  20. Scalable production of controllable dermal papilla spheroids on PVA surfaces and the effects of spheroid size on hair follicle regeneration.

    PubMed

    Huang, Yi-Ching; Chan, Chih-Chieh; Lin, Wei-Ting; Chiu, Hsien-Yi; Tsai, Ren-Yeu; Tsai, Tsung-Hua; Chan, Jung-Yi; Lin, Sung-Jan

    2013-01-01

    Organ size and numbers are vital issues in bioengineering for hair follicle (HF) regeneration. Murine HF dermal papilla (DP) cells are able to induce HF neogenesis when transplanted as aggregates. However, how the preparation of murine and human DP aggregates affects HF inductivity and the size of regenerated HF is yet to be determined. Here we report a scalable method for production of controllable human and rat DP spheroids in general labs for reproducible experiments. Compared with more hydrophobic polyethylene and poly(ethylene-co-vinyl alcohol), DP cells are poorly adhesive to hydrophilic polyvinyl alcohol (PVA). Seeded in PVA-coated 96-welled commercial PCR tube arrays, DP cells quickly aggregate into single spheroids with progressive compaction. Varying seeded cell numbers and culture periods enables us to control the size and cell number of the spheroids. The spheroids obtained have high viability and preserve DP characters. A proof of principle experiment was conducted to examine the size effect on the efficiency and efficacy of HF regeneration. We found that both human and rat DP spheroids are able to induce HF neogenesis and larger DP spheroids exhibit higher HF inductivity. However, the average diameter of regenerated hair fiber did not significantly change with the increasing size of transplanted DP spheroids. The result suggests that an appropriate size of DP spheroid is essential for HF inductivity, but its size cannot be directly translated to a thicker regenerated hair. Our results also have implications on the efficiency and efficacy in the regeneration of other epithelial organs. PMID:23092862

  1. Preparation of the poly(vinyl alcohol)/layered double hydroxide nanocomposite

    SciTech Connect

    Li Baoguang; Hu Yuan; Zhang Rui; Chen Zuyao; Fan Weicheng

    2003-10-01

    Intercalated nanocomposite based on Mg, Al layered double hydroxide (LDH) and poly(vinyl alcohol) (PVA) was prepared using exfoliation-adsorption technique, and characterized by X-ray diffraction and thermal gravimetric analysis. The results suggest that the intercalated species are formed via the re-aggregation of the delaminated LDH lamellar with the interlayer spacing 14.5 A, and the thermal stability of the nanocomposite improved compared with the original PVA.

  2. Thermodynamic properties of aqueous-alcoholic solutions of sodium chloride. H2O-2-C3H7OH-NaCl

    NASA Astrophysics Data System (ADS)

    Veryaeva, E. S.; Konstantinova, N. M.; Mamontov, M. N.; Uspenskaya, I. A.

    2010-11-01

    The temperature-concentration dependences of the NaCl activity coefficient in aqueous solutions of isopropanol (propanol-2) at temperatures of 298.15 and 323.15 K (solution ionic force, 0.01 to 3 m; alcohol content, 10-60 wt %) were determined through the electromotive force method with an ion-selective electrode. A Pitzer model was used to mathematically describe the thermodynamic properties. The integral Gibbs energy of the solution formation of the H2O-2-C3H7OH-NaCl ternary system was performed according to Darken's method. The dissociation degree of salt in the investigated solutions was estimated using the literature data on the association constant of NaCl in aqueous-isopropanol solution.

  3. Nucleation of CaCO3 polymorphs from a colloidal alcoholic solution of Ca(OH)2 nanocrystals exposed to low humidity conditions

    NASA Astrophysics Data System (ADS)

    Gomez-Villalba, L. S.; López-Arce, P.; Fort, R.

    2012-01-01

    A study of the stability of calcium carbonate polymorphs formed as a result of the carbonation process from an alcoholic colloidal solution of nanocrystals of Ca(OH)2 in low relative humidity (RH) conditions (33% and 54% RH) is presented in this research. The crystalline behavior, the time dependence of nucleation and the phases' transformations as a result of exposure to low humidity conditions are evaluated. The carbonation process is slow, starting with the nucleation of amorphous calcium carbonate, associated to an amorphization process that affects both the portlandite (Ca(OH)2) and the initial unstable CaCO3 polymorphs. The excess of alcohol in the solution decreases the surface tension and the nucleation is accelerated by the fast evaporation of the solvent, which avoids the particles to diffuse to their lowest energy sites, giving smaller particles with lower crystallinity as RH decreases.

  4. Experimental and numerical tribological studies of a boundary lubricant functionalized poro-viscoelastic PVA hydrogel in normal contact and sliding.

    PubMed

    Blum, Michelle M; Ovaert, Timothy C

    2012-10-01

    Hydrogels are a cross-linked network of polymers swollen with liquid and have the potential to be used as a synthetic replacement for local defects in load bearing tissues such as articular cartilage. Hydrogels display viscoelastic time dependent behavior, therefore experimental analysis of stresses at the surface and within the gel is difficult to perform. A three-dimensional model of a hydrogel was developed in the commercial finite element software ABAQUS™, implementing a poro-viscoelastic constitutive model along with a contact-dependent flow state and friction conditions. Water content measurements, sliding, and indentation experiments were performed on neat polyvinyl alcohol (PVA), and on low friction boundary lubricant functionalized (BLF-PVA) hydrogels, both manufactured by freeze-thaw processes. Modulus results from the indentation experiments and coefficient of friction values from the sliding experiments were used as material property inputs to the model, while water content was used to calculate initial flow conditions. Tangential force and normal displacement data from a three-dimensional simulation of sliding were compared with the experiments. The tangential force patterns indicated important similarities with the fabricated hydrogels that included an initially high force value due to time dependent deformation followed by a decrease in a stabile value. A similar trend was observed with the normal displacement. These comparisons rendered the model suitable as a representation and were used to analyze the development and propagation of stresses in the immediate surface region. The results showed that in a three-dimensional stress field during sliding, the maximum stress shifted to the surface and rotated closer to the leading edge of contact. This occurred because the stress field becomes dominated by an amplified compressive stress at the leading edge due to the biphasic viscoelastic response of the material during sliding. Also, the complex multi

  5. Facile synthesis of boehmite/PVA composite membrane with enhanced adsorption performance towards Cr(VI).

    PubMed

    Luo, Lei; Cai, Weiquan; Zhou, Jiabin; Li, Yuanzhi

    2016-11-15

    A novel boehmite/PVA composite membrane (BPCM) with remarkably enhanced adsorption performance towards Cr(VI) was successfully synthesized from Al(NO3)3·9H2O using HAc as the peptizing agent via a facile sol-gel method. The physicochemical properties of the BPCM, the boehmite powder (BP) without PVA and a commercial boehmite powder (CBP) were comparatively characterized by XRD, TGA-DSC, FT-IR and XPS. Batch adsorption experiments showed that the adsorption performance of the BPCM is much better than those of BP and CBP. Its adsorption process was well described by the pseudo-second-order kinetic model, and its equilibrium data fit the Langmuir isotherm well with a maximum adsorption capacity of 36.41mgg(-1). Its interference adsorption experiment in presence of coexisting anions showed that SO4(2-) and HPO4(2-) have greater effect than those of the Cl(-), F(-), C2O4(2-) and HCO3(-). A three step action mechanism including adsorption of Cr(VI) anions, complexation between Cr(VI) anions and the functional groups on the surface of BPCM, and the reduction of Cr(VI) to Cr(III) was proposed to illustrate the adsorption process. This efficient film could be easily separated after adsorption, exhibiting great potential for the removal of Cr(VI) from aqueous solution, and other fields of environmental remediation. PMID:27450337

  6. Optical, electrical, thermal properties of cadmium chloride doped PVA - PVP blend

    NASA Astrophysics Data System (ADS)

    Baraker, Basavarajeshwari M.; Hammannavar, Preeti B.; Lobo, Blaise

    2015-06-01

    Films of polyvinylalcohol (PVA) - polyvinylpyrrolidone (PVP) blend doped with Cadmium Chloride (CdCl2) in the doping range 1 wt% to 40 wt% were prepared by solution casting technique. These films were characterized using optical/UV-Vis- NIR spectroscopy, Differential Scanning Calorimetry (DSC) and DC electrical measurements. The UV-Visible spectra were quantitatively analyzed to yield the optical parameters. The UV-Visible Spectra show intermediate absorption bands (before the final absorption edge) due to formation of energy bands in the forbidden gap of PVA-PVP. There is a prominent absorption band at 2.9 eV, from 0.5 wt% up to 1.8 wt% doping level (DL) caused by the dopant (CdCl2). The DC electrical studies showed an increase in activation energy from 2.8 eV at 0.5 wt% DL up to 3.5 eV at 4.4 wt% DL, reaching a low of 2.4 eV at 11.2 wt% DL. DSC scans show evidence of formation of chain fragments, at doping levels beyond 8 wt%.

  7. Optical, electrical, thermal properties of cadmium chloride doped PVA – PVP blend

    SciTech Connect

    Baraker, Basavarajeshwari M.; Hammannavar, Preeti B.; Lobo, Blaise

    2015-06-24

    Films of polyvinylalcohol (PVA) – polyvinylpyrrolidone (PVP) blend doped with Cadmium Chloride (CdCl{sub 2}) in the doping range 1 wt% to 40 wt% were prepared by solution casting technique. These films were characterized using optical/UV-Vis- NIR spectroscopy, Differential Scanning Calorimetry (DSC) and DC electrical measurements. The UV-Visible spectra were quantitatively analyzed to yield the optical parameters. The UV-Visible Spectra show intermediate absorption bands (before the final absorption edge) due to formation of energy bands in the forbidden gap of PVA-PVP. There is a prominent absorption band at 2.9 eV, from 0.5 wt% up to 1.8 wt% doping level (DL) caused by the dopant (CdCl{sub 2}). The DC electrical studies showed an increase in activation energy from 2.8 eV at 0.5 wt% DL up to 3.5 eV at 4.4 wt% DL, reaching a low of 2.4 eV at 11.2 wt% DL. DSC scans show evidence of formation of chain fragments, at doping levels beyond 8 wt%.

  8. The enthalpy of solution of DL-α-alanyl-DL-α-valine depending on the composition of water-alcohol binary solvents at 298.15 K

    NASA Astrophysics Data System (ADS)

    Smirnov, V. I.; Badelin, V. G.

    2008-12-01

    The integral enthalpies of solution of DL-α-alanyl-DL-α-valine in water-ethanol, water- n-propanol, and water-isopropanol mixtures at alcohol concentrations x 2 = 0-0.4 mole fractions were measured calorimetrically. The enthalpies of solution of the peptide Δsol H° and transfer from water to a mixed solvent Δtr H° were calculated. The effect of the structure and properties of the peptide and mixture composition on the enthalpy characteristics of the peptide are discussed. The enthalpy coefficients of pair interactions h xy of DL-α-alanyl-DL-α-valine with alcohol molecules were calculated. It was found that they were positive and increased in the series ethanol, n-propanol, isopropanol. An analysis of the results allows the general features of changes in the thermodynamic parameters of solution of peptides of the DL-α-alanine series with different amino acid residues in water-alcohol mixtures to be established.

  9. Ca3(PO4)2 precipitated layering of an in situ hybridized PVA/Ca2O4Si nanofibrous antibacterial wound dressing.

    PubMed

    Mabrouk, Mostafa; Choonara, Yahya E; Marimuthu, Thashree; Kumar, Pradeep; du Toit, Lisa C; van Vuuren, Sandy; Pillay, Viness

    2016-06-30

    The aim of this study was to develop an in situ hybridized poly(vinyl alcohol)/calcium silicate (PVA/Ca2OSi) nanofibrous antibacterial wound dressing with calcium phosphate [Ca3(PO4)2] surface precipitation for enhanced bioactivity. This was achieved by hybridizing the antibacterial ions Zn(2+) and/or Ag(+) in a Ca2O4Si composite. The hybridization effect on the thermal behavior, physicochemical, morphological, and physicomechanical properties of the nanofibers was studied using Differential Scanning calorimetric (DSC), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and Textural Analysis, respectively. In vitro bioactivity, biodegradation and pH variations of the nanofiber composite were evaluated in Simulated Body Fluid (SBF). The antibacterial activity was assessed against Staphylococcus aureus and Pseudomonas aeruginosa. Hybridization of Zn(2+) and/or Ag(+) into the PVA/Ca2O4Si nanofiber composite was confirmed by DSC, XRD and FTIR. The thickness of the nanofibers was dependent on the presence of Zn(2+) and Ag(+) as confirmed by SEM. The nanofibers displayed enhanced tensile strength (19-115.73MPa) compared to native PVA. Zn(2+) and/or Ag(+) hybridized nanofibers showed relatively enhanced in vitro bioactivity, biodegradation (90%) and antibacterial activity compared with the native PVA/Ca2O4Si nanofiber composite. Results of this study has shown that the PVA/Ca2O4Si composite hybridized with both Zn(2+) and Ag(+) may be promising as an antibacterial wound dressing with a nanofibrous archetype with enhanced bioactivity. PMID:27154257

  10. 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.

  11. 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.

  12. Structural and biological evaluation of a multifunctional SWCNT-AgNPs-DNA/PVA bio-nanofilm.

    PubMed

    Subbiah, Ramesh P; Lee, Haisung; Veerapandian, Murugan; Sadhasivam, Sathya; Seo, Soo-Won; Yun, Kyusik

    2011-04-01

    A bio-nanofilm consisting of a tetrad nanomaterial (nanotubes, nanoparticles, DNA, polymer) was fabricated utilizing in situ reduction and noncovalent interactions and it displayed effective antibacterial activity and biocompatibility. This bio-nanofilm was composed of homogenous silver nanoparticles (AgNPs) coated on single-walled carbon nanotubes (SWCNTs), which were later hybridized with DNA and stabilized in poly(vinyl alcohol) (PVA) in the presence of a surfactant with the aid of ultrasonication. Electron microscopy and bio-AFM (atomic force microscopy) images were used to assess the morphology of the nanocomposite (NC) structure. Functionalization and fabrication were examined using FT-Raman spectroscopy by analyzing the functional changes in the bio-nanofilm before and after fabrication. UV-visible spectroscopy and X-ray powder diffraction (XRD) confirmed that AgNPs were present in the final NC on the basis of its surface plasmon resonance (370 nm) and crystal planes. Thermal gravimetric analysis was used to measure the percentage weight loss of SWCNT (17.5%) and final SWCNT-AgNPs-DNA/PVA (47.7%). The antimicrobial efficiency of the bio-nanofilm was evaluated against major pathogenic organisms. Bactericidal ratios, zone of inhibition, and minimum inhibitory concentration were examined against gram positive and gram negative bacteria. A preliminary cytotoxicity analysis was conducted using A549 lung cancer cells and IMR-90 fibroblast cells. Confocal laser microscopy, bio-AFM, and field emission scanning electron microscopy (FE-SEM) images demonstrated that the NCs were successfully taken up by the cells. These combined results indicate that this bio-nanofilm was biocompatible and displayed antimicrobial activity. Thus, this novel bio-nanofilm holds great promise for use as a multifunctional tool in burn therapy, tissue engineering, and other biomedical applications. PMID:21336791

  13. Rainfastness of Poly(vinyl alcohol) Deposits on Vicia faba Leaf Surfaces: From Laboratory-Scale Washing to Simulated Rain.

    PubMed

    Symonds, Brett L; Thomson, Niall R; Lindsay, Christopher I; Khutoryanskiy, Vitaliy V

    2016-06-01

    Rainfastness is the ability of agrochemical deposits to resist wash-off by rain and other related environmental phenomena. This work reports laboratory-scale and raintower studies of the rainfastness of fluorescently labeled poly(vinyl alcohol) (PVA) using fluorescent microscopy combined with image analysis. Samples of hydrolyzed PVA exhibit improved rainfastness over a threshold molecular weight, which correlates with PVA film dissolution, swelling, and crystalline properties. It was also established that the rainfastness of PVA scaled with the molecular weight over this threshold. These PVA samples were further characterized in order to determine the effect of the crystallinity on rainfastness. The quantification of rainfastness is of great interest to the field of agrochemical formulation development in order to improve the efficacy of pesticides and their adjuvants. PMID:27070864

  14. 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 m...

  15. Environmentally friendly Zn0.75Cd0.25S/PVA heterosystem nanocomposite: UV-stimulated emission and absorption spectra

    NASA Astrophysics Data System (ADS)

    Imam, N. G.; Mohamed, Mohamed Bakr

    2016-02-01

    Zn0.75Cd0.25S nanoparticles prepared at different temperatures were composited with polyvinyl alcohol for functionalization it in wide spectrum of applications such as in photocatalysis. The nanostructure of the Zn0.75Cd0.25S mother phase is confirmed by X-ray diffraction in addition to absorption and fluorescence spectra. UV/VIS. measurements show that, the transmittance coefficient of Zn0.75Cd0.25S/PVA nanocomposite is lesser than that of pure PVA by 0.33% and varies upon increasing the preparation temperature; reaching a maximum value for the sample prepared at 300 °C. It was found that the optical band gap tunes with annealing temperature which, in turns, with particle size. The refractive index of the Zn0.75Cd0.25S/PVA nanocomposite films decrease with increasing wavelength and saturates at high wavelengths. The optical conductivity increases with increasing photon energy which may be due to the excitation of electrons by photon energy. The optical conductivity of Zn0.75Cd0.25S/PVA nanocomposite is lesser than that of pure PVA and it decreases as the preparation temperature of Zn0.75Cd0.25S nanoparticles in PVA matrix increases which could be related to the decrease in the extinction coefficient and the density of localized states in the gap. Abroad peak deconvoluted, by Gaussian fitting function, into two violet and blue colors was observed in the fluorescence spectra under UV light irradiation. The two emission bands are attributed to band edge emission and neutral oxygen vacancies respectively. Analysis of fluorescence (FL) spectra reveals quenching in FL intensity and a peak shifting towards the lower wavelength side with increasing the preparation temperature of the mother phase. The results suggest that the 200 °C Zn0.75Cd0.25S/PVA nanocomposites have been regarded as a promising candidate in many technical fields, such as photocatalytic hydrogen production and/or photocatalytic degradation of organic dyes under UV irradiation due to its high optical

  16. Soft X-ray induced damage in PVA-based membranes in water environment monitored by X-ray absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Tzvetkov, George; Späth, Andreas; Fink, Rainer H.

    2014-10-01

    The effect of synchrotron X-ray flux in a soft X-ray scanning-transmission microspectroscope (STXM) instrument on the chemical structure of air-filled poly(vinyl alcohol) (PVA) based microbubbles and their stabilizing shell has been examined. Prolonged soft X-ray illumination of the particles in aqueous suspension leads to the breaking of the microbubbles' protective polymer shell and substantial chemical changes. The latter were clarified via a micro-spot C K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with further respect to the absorbed X-ray doses. Our results revealed a continuous degradation of the PVA network associated with formation of carbonyl- and carboxyl-containing species as well as an increased content of unsaturated bonds. The observed effects must be taken into account in studies of micro- and nanostructured polymer materials utilizing X-rays.

  17. Polyvinyl alcohol membranes as alkaline battery separators

    NASA Technical Reports Server (NTRS)

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

    1982-01-01

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

  18. Soy proteins as environmentally friendly sizing agents to replace poly(vinyl alcohol).

    PubMed

    Chen, Lihong; Reddy, Narendra; Yang, Yiqi

    2013-09-01

    An environmentally friendly and inexpensive substitute to the widely used poly(vinyl alcohol) (PVA) has been developed from soy proteins for textile warp sizing. Textile processing is the major source of industrial water pollution across the world, and sizing and desizing operations account for nearly 30 % of the water consumed in a textile plant. PVA is one of the most common sizing agents used for synthetic fibers and their blends due to PVA's easy water solubility and ability to provide desired sizing performance. However, PVA does not degrade and is a major contributor to pollution in textile effluent treatment plants. Although considerable efforts have been made to replace PVA with biodegradable sizing materials, the performance properties provided by PVA on synthetic fibers and their blends have been unmatched so far. Soy proteins are inexpensive, biodegradable, and have been widely studied for potential use in food packaging, as resins and adhesives. In this research, the potential of using soy proteins as textile sizing agents to replace PVA was studied. Polyester and polyester/cotton rovings, yarns, and fabrics sized with soy protein showed a considerably better improvement in strength and abrasion resistance compared to commercially available PVA-based size. Soy protein size had a 5-day biochemical oxygen demand /chemical oxygen demand ratio of 0.57 compared to 0.01 for PVA indicating that soy protein sizes were easily biodegradable in activated sludge. The total and ammonia nitrogen released from the proteins also did not adversely impact the biodegradability. Good sizing performance and easy biodegradability demonstrate that soy protein-based sizes have potential to replace PVA-based sizes leading to substantial benefits to the textile industry and the environment. PMID:23536274

  19. PIV measurements of flow in drying polymer solutions during solvent casting

    NASA Astrophysics Data System (ADS)

    Mansoor, Iman; Stoeber, Boris

    2011-05-01

    An experimental method based on confocal microscopy and particle image velocimetry (PIV) is used to characterize the flow in a polymer solution during solvent casting. The flow inside a 200-μm-thick film of a poly(vinyl alcohol) (PVA) solution is visualized near a vertical wall of a mold using confocal microscopy of seed particles during solvent evaporation at 25, 35, and 45°C, and the corresponding velocity vector fields are determined from projections of the confocal images. Flow toward the vertical wall is observed inside the film as well as a slower Marangoni-type counter flow at the film surface during the initial phase of solvent evaporation, resulting from a polymer concentration gradient along the film due to a local variation in evaporation rate. Total volume of the polymer solution in the observation volume as well as solvent evaporation rate are determined as a function of time, both revealing close correlation to average horizontal velocity data from PIV. The PIV measurements show significant differences in the flow velocity fields at different temperatures. The PIV measurements correlate with the solvent evaporation rates as well as the final polymer thicknesses on the vertical wall of the mold. Surface tension and viscosity measurements are taken for different concentrations of PVA solution.

  20. Synthesis of biphenyl derivative and its application as dichroic materials in poly (vinyl alcohol) polarizing films

    NASA Astrophysics Data System (ADS)

    Shahab, Siyamak; Almodarresiyeh, Hora A.; Filippovich, Ljudmila; Kumar, Rakesh; Darroudi, Mahdieh; Hajikolaee, Fatemeh Haji

    2016-03-01

    In the present work, first time on the basis of polyvinyl alcohol (PVA) and new designed structure (Potassium 2,2‧-([1,1‧-biphenyl]-4,4‧-diylbis(azanediyl))diacetate) (I) thermostable polarizing film was created. The structure (I) was first modeled and then synthesized and obtained polarizing film absorbing at λmax = 300 nm used for electronic applications. Polarizing efficiency (PE) of polarizing film is 96% at stretching degree (Rs) 4.0. On the basis of PVA, Potassium 2,2‧-([1,1‧-biphenyl]-4,4‧-diylbis(azanediyl))diacetate (I), Sodium 2-hydroxy-5-((2-methoxy-4-((4-sulfonatophenyl)diazenyl)phenyl)diazenyl)benzoate (II) and commercial dye (Congo Red) thermostable polarizing film for wide spectral range of spectrum (λmax = 288-561 nm) was developed. During the work it was established that oriented PVA-films is phenomenon of anisotropy of thermal conductivity (λ||/λ⊥). It is very important for creation of thermostable polarizing films. Thermal conductivity in a direction of orientation (λ||) is higher than in a direction perpendicular orientations (λ⊥). The optimization of the molecule (1) was carried out by Density Functional Theory (DFT) using B3LYP/6-311 + G* method. Electronic absorption spectrum of the molecule (I) in dimethylformamide (DMF) solution was calculated using TDB3LYP/6-311 + G* level. The nature of absorption bands in the UV spectral region was interpreted.

  1. Preparation of a Nanoscaled Poly(vinyl alcohol)/Hydroxyapatite/DNA Complex Using High Hydrostatic Pressure Technology for In Vitro and In Vivo Gene Delivery

    PubMed Central

    Kimura, Tsuyoshi; Nibe, Yoichi; Funamoto, Seiichi; Okada, Masahiro; Furuzono, Tsutomu; Ono, Tsutomu; Yoshizawa, Hidekazu; Fujisato, Toshiya; Nam, Kwangwoo; Kishida, Akio

    2011-01-01

    Our previous research showed that poly(vinyl alcohol) (PVA) nanoparticles incorporating DNA with hydrogen bonds obtained by high hydrostatic pressurization are able to deliver DNA without any significant cytotoxicity. To enhance transfection efficiency of PVA/DNA nanoparticles, we describe a novel method to prepare PVA/DNA nanoparticles encapsulating nanoscaled hydroxyapatites (HAps) prepared by high hydrostatic pressurization (980 MPa), which is designed to facilitate endosomal escape induced by dissolving HAps in an endosome. Scanning electron microscopic observation and dynamic light scattering measurement revealed that HAps were significantly encapsulated in PVA/HAp/DNA nanoparticles. The cytotoxicity, cellular uptake, and transgene expression of PVA/HAp/DNA nanoparticles were investigated using COS-7 cells. It was found that, in contrast to PVA/DNA nanoparticles, their internalization and transgene expression increased without cytotoxicity occurring. Furthermore, a similar level of transgene expression between plasmid DNA and PVA/HAp/DNA nanoparticles was achieved using in vivo hydrodynamic injection. Our results show a novel method of preparing PVA/DNA nanoparticles encapsulating HAp nano-crystals by using high hydrostatic pressure technology and the potential use of HAps as an enhancer of the transfection efficiency of PVA/DNA nanoparticles without significant cytotoxicity. PMID:21773048

  2. Evaluation and modeling of thermal kinetic degradation for PVA doped PbS quantum dot

    SciTech Connect

    Mahmoud, Waleed E.; Al-Heniti, S.H.

    2011-09-15

    Highlights: {yields} Synthesis of PVA doped PbS quantum dots. {yields} Data fitting using integral and differential thermal kinetic models for calculating activation energy. {yields} Prediction of thermal degradation using iso-conversion model. -- Abstract: The kinetic analysis of the thermogravimetric curves for the thermal decomposition processes of PVA/PbS was performed. The samples were heated in nitrogen, with three different heating rates: 10, 20 and 30 {sup o}C min{sup -1}. Various forms of non-isothermal methods of analysis for determining the kinetic parameters were used. The differential and integral models were used to calculate the activation energies. Comparing with pure PVA, the results showed that the maximum activation energy of thermal degradation is achieved for PVA/PbS nanocomposite. Isoconversion model is used for predicting the thermal degradation acceleration. The results showed that the acceleration of thermal degradation for pure PVA was faster than PVA/PbS nanocomposite.

  3. Strength Development of High-Strength Ductile Concrete Incorporating Metakaolin and PVA Fibers

    PubMed Central

    Nuruddin, Muhammad Fadhil; Shafiq, Nasir

    2014-01-01

    The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers. PMID:24707202

  4. Strength development of high-strength ductile concrete incorporating Metakaolin and PVA fibers.

    PubMed

    Nuruddin, Muhammad Fadhil; Khan, Sadaqat Ullah; Shafiq, Nasir; Ayub, Tehmina

    2014-01-01

    The mechanical properties of high-strength ductile concrete (HSDC) have been investigated using Metakaolin (MK) as the cement replacing material and PVA fibers. Total twenty-seven (27) mixes of concrete have been examined with varying content of MK and PVA fibers. It has been found that the coarser type PVA fibers provide strengths competitive to control or higher than control. Concrete with coarser type PVA fibers has also refined microstructure, but the microstructure has been undergone with the increase in aspect ratio of fibers. The microstructure of concrete with MK has also more refined and packing of material is much better with MK. PVA fibers not only give higher stiffness but also showed the deflection hardening response. Toughness Index of HSDC reflects the improvement in flexural toughness over the plain concrete and the maximum toughness indices have been observed with 10% MK and 2% volume fraction of PVA fibers. PMID:24707202

  5. Development of polyvinyl alcohol and apple pomace bio-composite film with antioxidant properties for active food packaging application.

    PubMed

    Gaikwad, Kirtiraj K; Lee, Jin Yong; Lee, Youn Suk

    2016-03-01

    Active antioxidant food packaging films were developed by incorporation of apple pomace (AP) with 1, 5, 10, and 30 % (w/w) into polyvinyl alcohol (PVA) matrix. A complete thermal, structural, mechanical and functional characterization was carried out. The findings of this study showed that the incorporation of AP into PVA films enhanced the total phenolic content and antioxidant properties. As regards the physical properties, higher AP content incorporated into PVA films revealed significantly lower tensile strength, elongation at break and increase in thickness. PVA-AP films exhibited lower transparency value compared to control film. The thermal stability of PVA-AP films was improved and grew with the increasing concentration of AP. FTIR spectra indicated that protein-polyphenol interactions were involved in the PVA-AP films. Rough surface and compact-structure were observed in PVA-AP films. The storage study of soybean oil at 60 °C in PVA-AP pouch showed the antioxidant activity and the effectiveness for delaying its lipid oxidation. PMID:27570286

  6. Photocatalytic reduction of Cr(VI) in aqueous solution using TiO₂ nanoparticles prepared with various alcohols as solvent.

    PubMed

    Ku, Young; Lin, Chia-Nan; Hou, Wei-Ming

    2012-01-01

    TiO₂ nanoparticles were prepared with various linear alkyl chains of alcohols under a sol-gel process. The structure characterization and the photocatalytic reduction of hexavalent chromium of the TiO₂ nanoparticles were investigated. The phase transformation temperature, crystal aggregation and surface area of prepared TiO₂ samples were found to be strongly influenced by alcohol used. The phase transformation from anatase to rutile was retarded and the surface area was reduced for TiO₂ prepared with alcohols of longer alkyl chain. TiO₂ nanoparticles prepared with methanol or ethanol exhibited higher photocatalytic reduction activity of hexavalent chromium possibly due to greater and more positively charged surface area. PMID:22828314

  7. Numerical investigation on the structural characteristics of multiple RBCs in a stenotic microcapillary under plasma-alcohol solution

    NASA Astrophysics Data System (ADS)

    Ni, Aleksey; Cheema, Taqi Ahmad; Park, Cheol Woo

    2015-05-01

    Alcohol significantly affects blood rheology and influences the mechanical behavior of red blood cells (RBCs). Previous studies indicate that plasma-RBC and multiple RBC interaction are important indicators for atherosclerosis progression. Therefore, multiphysics interactions under highly viscous conditions of alcohol consumption and stenosis structure must be investigated. A 2D microcapillary model, wherein multiple RBCs float through a stenotic structure, was established to investigate the effect of alcohol on cell motion and deformability under various flow conditions. Results show that the deformed cells inside the stenosis increase flow resistance and increase plasma velocity gradient in the pre and post stenotic regions. Moreover, the effect of the initial RBC position is important describing the RBC deformation pattern. The structural properties of RBCs may be significantly affected when the stenosis path is filled by cells that increase flow resistance.

  8. Complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) in aqueous solution.

    PubMed

    Canepari, S; Carunchio, V; Castellano, P; Messina, A

    1998-12-01

    A study of complex formation equilibria of some beta-amino-alcohols with lead(II) and cadmium(II) ions at 25 degrees C and in 0.5 M KNO(3) is reported. The amino-alcohols considered are 2-amino-1-propanol, 2-amino-1-butanol, 2-amino-1-pentanol and 2-amino-1,3-propanediol. sec-Buthylamine and 2-amino-1-methoxy-propane have been also considered for comparison. The results are discussed in terms of ligand structure, paying attention to the number of hydroxyl groups and to the length of the alkyl residual. A weak contribution of the alcoholic oxygen in the coordination of cadmium(II) and the presence of a mixed hydroxyl species in lead(II) containing systems are hypothesized. PMID:18967412

  9. 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. PMID:23399282

  10. 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.

  11. 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. PMID:24299887

  12. Effect of different polyol-based plasticizers on thermal properties of polyvinyl alcohol:starch blends.

    PubMed

    Aydın, Ahmet Alper; Ilberg, Vladimir

    2016-01-20

    A series of gelatinized polyvinyl alcohol (PVA):starch blends were prepared with various polyol-based plasticizers in 5 wt%, 15 wt% and 25 wt% ratios via solution casting method. The obtained films were analyzed by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Remarkable changes have been observed in glass-transition temperature (Tg) and thermal stability of the samples containing varying concentrations of different plasticizers and they have been discussed in detail with respect to the conducted thermal and chemical analyses. The observed order of Tg point depression of the samples containing 15 wt% plasticizer is 1,4-butanediol - 1,2,6-hexanetriol--pentaerythriyol--xylitol--mannitol, which is similar to the sequence of the thermal stability changes of the samples. PMID:26572374

  13. Alcohol Alert

    MedlinePlus

    ... main content National Institute on Alcohol Abuse and Alcoholism (NIAAA) Main Menu Search Search form Search Alcohol & ... on a single aspect of alcohol abuse and alcoholism. Please click on the desired publication for full ...

  14. 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. PMID:24299821

  15. Nonvolatile memory devices based on poly(vinyl alcohol) + graphene oxide hybrid composites.

    PubMed

    Sun, Yanmei; Lu, Junguo; Ai, Chunpeng; Wen, Dianzhong

    2016-04-20

    Nonvolatile memory devices based on active layers of poly(vinyl alcohol) (PVA) + graphene oxide (GO) hybrid composites have been fabricated. The performance of the ITO/PVA + GO/Al device was compared with that of the ITO/PVA/Al device. The ITO/PVA + GO/Al device showed excellent performance compared to the ITO/PVA/Al device (an ON/OFF resistance ratio of 1.2 × 10(2) at 1 V, VSET ∼ -1.45 V and VRESET ∼ 3.6 V), with a higher ON/OFF resistance ratio of 3 × 10(4) at 1 V and lower operating voltages of VSET ∼ -0.75 V and VRESET ∼ 3.0 V. Furthermore, endurance performance and write-read-erase-reread (WRER) cycle tests manifest that the presence of GO in ITO/PVA + GO/Al devices makes them have better stability and repeatability. The results show that the performance of hybrid devices can be effectively enhanced by the introduction of GO into the PVA matrix. PMID:27056548

  16. Mucoadhesive polymers: Synthesis and in vitro characterization of thiolated poly(vinyl alcohol).

    PubMed

    Suchaoin, Wongsakorn; Pereira de Sousa, Irene; Netsomboon, Kesinee; Rohrer, Julia; Hoffmann Abad, Patricia; Laffleur, Flavia; Matuszczak, Barbara; Bernkop-Schnürch, Andreas

    2016-04-30

    The aim of this study was to synthesize thiolated poly(vinyl alcohol) (PVA) and to evaluate its mucoadhesive properties. Thiourea and 3-mercaptopropionic acid were utilized in order to obtain thiolated PVAs, namely, TPVA1 and TPVA2, respectively. TPVA1 and TPVA2 displayed 130.44±14.99 and 958.35±155.27μmol immobilized thiol groups per gram polymer, respectively, which were then evaluated regarding reactivity of thiol groups, swelling behavior and mucoadhesive properties. Both thiolated PVAs exhibited the highest reactivity at pH 8.0 whereas more than 95% of free thiol groups were preserved at pH 5.0. Thiolation of PVA decelerated water uptake and prolonged disintegration time of test discs compared to unmodified PVA. Contact time of TPVA1- and TPVA2-based test discs on porcine intestinal mucosa was 3.2- and 15.8-fold prolonged, respectively, in comparison to non-thiolated PVA as measured by rotating cylinder method. According to tensile studies on mucosa, the total work of adhesion (TWA) and the maximum detachment force (MDF) were increased when compared to PVA. Furthermore, thiolated PVAs preserved higher percentage of viable cells compared to unmodified PVA within 24h as evaluated by MTT assay. Accordingly, thiolated PVA represents a novel excipient that can likely improve the mucoadhesive properties of various pharmaceutical formulations. PMID:26965199

  17. 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

    2015-04-01

    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. PMID:25779354

  18. 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.

  19. Improvement of mechanical robustness of the superhydrophobic wood surface by coating PVA/SiO2 composite polymer

    NASA Astrophysics Data System (ADS)

    Liu, Feng; Wang, Shuliang; Zhang, Ming; Ma, Miaolian; Wang, Chengyu; Li, Jian

    2013-09-01

    Improvement of the robustness of superhydrophobic surfaces is crucial for the purpose of achieving commercial applications of these surfaces in such various areas as self-cleaning, water repellency and corrosion resistance. We have investigated a fabrication of polyvinyl alcohol (PVA)/silica (SiO2) composite polymer coating on wooden substrates with super repellency toward water, low sliding angles, low contact angle hysteresis, and relatively better mechanical robustness. The composite polymer slurry, consisting of well-mixing SiO2 particles and PVA, is prepared simply and subsequently coated over wooden substrates with good adhesion. In this study, the mechanical robustness of superhydrophobic wood surfaces was evaluated. The effect of petaloid structures of the composite polymer on robustness was investigated using an abrasion test and the results were compared with those of superhydrophobic wood surfaces fabricated by other processes. The produced wood surfaces exhibited promising superhydrophobic properties with a contact angle of 159̊ and a sliding angle of 4̊, and the relatively better mechanical robustness.

  20. Effect of incorporation of different modified Al2O3 nanoparticles on holographic characteristics of PVA/AA photopolymer composites.

    PubMed

    Li, Yunxi; Wang, Chunhui; Li, Hailong; Wang, Xiaoyi; Han, Junhe; Huang, Mingju

    2015-11-20

    Al2O3 nanoparticles modified with different chemical reagents, prepared by using three chemical dispersants [high definition (HD), sodium dodecyl benzene sulfonate, and cetyl trimethyl ammonium chloride], were doped into photopolymer films in a polyvinyl alcohol/acrylamide (PVA/AA) system, respectively. A 647 nm Ar-Kr laser was used to expose and study the holographic properties of the samples. The research shows that doping Al2O3 nanoparticles into PVA/AA photopolymer film leads to different levels of improvement of the holographic characteristics. The diffraction efficiency of the sample can be raised to 93.8%, the maximum refractive index modulation increased to 2.28×10(-3), the shrinkage can be depressed to 0.8%, and the Bragg mismatch is 0.04°, while the concentration of 10 nm Al2O3 nanoparticles modified by HD dispersant is 1.02×10(-3)  mol·L(-1). PMID:26836540

  1. Studies on photo- and thermal stability of PVA-encapsulated Mn-doped ZnS nanoparticles

    NASA Astrophysics Data System (ADS)

    Venkataramana, Savadana; Ramanaiah, K.; Sarcar, M. M. M.

    2016-04-01

    In this study, an aqueous-based synthesis route has been developed to prepare highly luminescent polyvinyl alcohol (PVA)-capped manganese-doped ZnS quantum dots (QDs). The QDs showed markedly blue shift in their optical absorbance, indicating strong quantum size effect and the average diameter of the QDs calculated ~3 nm. The QDs showed high-intensity Mn2+-related orange luminescence at 585 nm with a very low-intensity peak at 430 nm for the surface defect states. X-ray powder diffraction, transmission electron microscopy, UV-visible spectroscopy and spectrofluorometry have been used to characterize the doped QDs. Studies on the thermal and photochemical stability of the photoluminescence properties are carried out, which showed that after 5 h of photoexcitation and 30 min of 70 °C treatments, the nanoparticles retain almost 40 % of their initial quantum yield. Our systematic investigation shows that these PVA-capped Mn:ZnS QDs may be used as fluorescent labels in biological applications.

  2. The relationship between the adhesion work, the wettability and composition of the surface layer in the systems polymer/aqueous solution of anionic surfactants and alcohol mixtures

    NASA Astrophysics Data System (ADS)

    Zdziennicka, Anna; Jańczuk, Bronisław

    2010-11-01

    Measurements of advancing contact angle ( θ) were carried out on polytetrafluoroethylene (PTFE) and polymethylmethacrylate (PMMA) for aqueous solution of sodium dodecyl sulfate (SDDS) mixtures with methanol, ethanol and propanol in the range of SDDS concentration from 10 -5 to 10 -2 M, and for sodium hexadecyl sulfonate (SHS) with the same alcohols at the SHS concentration ranging from 10 -5 to 8 × 10 -4 M at 293 K. The concentration of methanol, ethanol and propanol used for measurements varied from 0 to 21.1, 11.97 and 6.67 M, respectively. On the basis of the contact angles the critical surface tension of PTFE and PMMA wetting was determined by using for this purpose the relationship between the adhesion and the surface tension and cos θ and surface tension both at constant alcohol and surfactant concentration, respectively. The obtained contact angles were also used in the Young Dupre' equation for calculations of the adhesion work of aqueous solution of mixtures of anionic surfactants and short chain alcohols to PTFE and PMMA surface. The adhesion work calculated in this way was compared to that of the particular components of aqueous solution to these surfaces determined on the basis of the surface tension components and parameters of the surface tension of the surface active agents, water, PTFE and PMMA from van Oss et al. equation. The calculated adhesion work was discussed in the light of the concentration of surface active agents at polymer-water and water-air interface determined from Lucassen-Reynders, Gibbs and Guggenheim-Adam equations.

  3. Alcoholism, Alcohol, and Drugs

    ERIC Educational Resources Information Center

    Rubin, Emanuel; Lieber, Charles S.

    1971-01-01

    Describes research on synergistic effects of alcohol and other drugs, particularly barbiturates. Proposes biochemical mechanisms to explain alcoholics' tolerance of other drugs when sober, and increased sensitivity when drunk. (AL)

  4. Handwashing compliance in a French university hospital: new perspective with the introduction of hand-rubbing with a waterless alcohol-based solution.

    PubMed

    Girou, E; Oppein, F

    2001-08-01

    The baseline compliance with handwashing in a French university hospital was as low as the compliance rates reported in other countries, i.e., less than 50%. By introducing the use of hand-rubbing with an alcoholic solution, as a substitution method for both handwashing with soap and handwashing with an antiseptic agent, we significantly improved hand-cleansing compliance. Despite these encouraging results, mainly due to the accessibility of these non-aqueous products, three major obstacles remain before a wide acceptance by healthcare workers: distrust in terms of efficacy, distrust in terms of skin tolerance and lack of knowledge on hand-cleansing indications. PMID:11759028

  5. Sulfur passivation of InSb(1 0 0) surfaces: Comparison of aqueous and alcoholic ammonium sulfide solutions using X-ray photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Lvova, Tatiana V.; Shakhmin, Aleksandr L.; Sedova, Irina V.; Lebedev, Mikhail V.

    2014-08-01

    The chemical composition and the electronic properties of the n-InSb(1 0 0) surface treated with ammonium sulfide dissolved in water or in 2-propanol has been studied by X-ray photoemission spectroscopy. The solvent determines the mechanism of chemical reaction between InSb(1 0 0) surface and sulfide solution. The variation of the solvent leads to variations in chemical composition and electronic structure of the final sulfide layers. Aqueous sulfide solution withdraws antimony atoms from the InSb(1 0 0) surface very fast due to solubility of antimony sulfides, whereas after treatment with alcoholic sulfide solution the antimony sulfides remain on the surface. The Fermi level at the InSb(1 0 0)/passivation layer interface occurs usually deeply in the conduction band of semiconductor and its position depends on the time of sulfur treatment. However, after prolonged treatment with aqueous sulfide solution and surface depletion with antimony the Fermi level is found in the valence band. Although both solutions remove the native oxide layer, the residual oxygen content is lower after treatment with the solution of ammonium sulfide in 2-propanol.

  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. PMID:26893051

  7. 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. PMID:26478388

  8. Poly(vinyl alcohol) Physical Hydrogels: Matrix-Mediated Drug Delivery Using Spontaneously Eroding Substrate.

    PubMed

    Jensen, Bettina E B; Dávila, Izaskun; Zelikin, Alexander N

    2016-07-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. 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.

  11. Polyurethane/poly(vinyl alcohol) hydrogel coating improves the cytocompatibility of neural electrodes

    PubMed Central

    Li, Mei; Zhou, Hai-han; Li, Tao; Li, Cheng-yan; Xia, Zhong-yuan; Duan, Yanwen Y.

    2015-01-01

    Neural electrodes, the core component of neural prostheses, are usually encapsulated in polydimethylsiloxane (PDMS). However, PDMS can generate a tissue response after implantation. Based on the physicochemical properties and excellent biocompatibility of polyurethane (PU) and poly(vinyl alcohol) (PVA) when used as coating materials, we synthesized PU/PVA hydrogel coatings and coated the surface of PDMS using plasma treatment, and the cytocompatibility to rat pheochromocytoma (PC12) cells was assessed. Protein adsorption tests indicated that the amount of protein adsorption onto the PDMS substrate was reduced by 92% after coating with the hydrogel. Moreover, the PC12 cells on the PU/PVA-coated PDMS showed higher cell density and longer and more numerous neurites than those on the uncoated PDMS. These results indicate that the PU/PVA hydrogel is cytocompatible and a promising coating material for neural electrodes to improve their biocompatibility. PMID:26889197

  12. 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.

  13. Effects of the ZnSe concentration on the structural and optical properties of ZnSe/PVA nanocomposite thin film

    NASA Astrophysics Data System (ADS)

    Halajan, M.; Torkamany, M. J.; Dorranian, D.

    2014-11-01

    This study investigated the effects of ZnSe nanoparticles (NPs) on the structural and (linear and nonlinear) optical properties of polyvinyl alcohol (PVA) thin film. Three samples of ZnSe NP-doped PVA thin films with different concentrations of ZnSe were produced on a glass substrate. The ZnSe NPs were synthesized by pulsed laser ablation of the ZnSe bulk target immersed in distilled water using a 1064 nm wavelength and a high frequency pulsed Nd:YAG laser. The optical bandgap energies of the films were extracted from their UV-Vis-NIR absorption spectra. The corresponding energy bandgaps of the nanocomposite films declined as the ZnSe NPs doping concentration increased. X-ray diffraction analysis was used to characterize the crystalline phases of the ZnSe/PVA nanocomposite films. The concentration-dependent nonlinear optical absorption and nonlinear refraction behaviors of the films after exposure to 532-nm nanosecond laser pulses were investigated using the Z-scan technique. The nonlinear absorption response of the films was positive when measured using an open aperture scheme, which was attributed to the two-photon absorption mechanism. In addition, the nonlinear refraction indices had a negative value and they increased as the concentration of ZnSe NPs in the films increased.

  14. Early malfunction of polyvinyl alcohol membrane of septal occluder.

    PubMed

    Ramoğlu, Mehmet G; Uçar, Tayfun; Tutar, Ercan

    2016-03-01

    Percutaneous device closure of atrial septal defect (ASD) is now considered the choice of treatment. Numerous devices with advantages/disadvantages are currently available and under development. Cardia Ultrasept II ASD occluder has a nitinol frame covered with polyvinyl alcohol (PVA) membrane. Here, a well-documented case of early malfunction of PVA membrane detected in the first week of implantation in a 4-year-old male patient, who underwent an uneventful device closure with 20 mm Cardia Ultrasept II ASD Occluder, is presented. One week after implantation left-to-right shunt through the device was detected and the explantation of device revealed PVA membrane with multiple perforations. © 2015 Wiley Periodicals, Inc. PMID:26106065

  15. Luminescent microstructures in bulk and thin films of PMMA, PDMS, PVA, and PS fabricated using femtosecond direct writing technique

    NASA Astrophysics Data System (ADS)

    Deepak, K. L. N.; Kuladeep, R.; Venugopal Rao, S.; Narayana Rao, D.

    2011-02-01

    We present here the luminescent properties of microstructures obtained through femtosecond (fs) laser direct writing (LDW) in bulk, and thin films of polymers such as poly methyl methacrylate (PMMA), poly dimethyl siloxane (PDMS), polystyrene (PS), and poly vinyl alcohol (PVA). We report the transmission, emission, excitation, laser confocal and ESR data from the modified regions acquired with the intention of understanding the fs irradiation effects in these polymers. Formation of different optical centers in the laser irradiated regions has been identified as the reason for emission characteristics which are dependent on the excitation source. Such emitting microstructures demonstrate their utility in memory based devices. ESR studies reveal the existence of peroxide type free radicals in PMMA, PDMS and PS after fs laser irradiation.

  16. Comparison of a new photosensitizer with erythrosine B in an AA/PVA-based photopolymer material.

    PubMed

    Qi, Yue; Li, Haoyu; Fouassier, Jean Pierre; Lalevée, Jacques; Sheridan, John T

    2014-02-20

    Dyes often act as the photoinitiator PI/photosensitizer PS in photopolymer materials and are therefore of significant interest. The properties of the PI/PS used strongly influences grating formation when the material layer is exposed holographically. In this paper, the ability of a recently synthesized dye, D_1, to sensitize an acrylamide/polyvinyl alcohol (AA/PVA) based photopolymer is examined, and the material performance is characterized using an extended nonlocal photopolymerization-driven diffusion model. Electron spin resonance spin-trapping (ESR-ST) experiments are also carried out to characterize the generation of the initiator/primary radical, R(•), during exposure. The results obtained are then compared with those for the corresponding situation when using a xanthene dye, i.e., erythrosine B, under the same experiment conditions. The results indicate that the nonlocal effect is greater when this new photosensitizer is used in the material. Analysis indicates that this is the case because of the dye's (D_1) weak absorptivity and the resulting slow rate of primary radical production. PMID:24663301

  17. Passive optical limiting studies of nanostructured Cu doped ZnO-PVA composite thin films

    NASA Astrophysics Data System (ADS)

    Tamgadge, Y. S.; Sunatkari, A. L.; Talwatkar, S. S.; Pahurkar, V. G.; Muley, G. G.

    2016-01-01

    We prepared undoped and Cu doped ZnO semiconducting nanoparticles (NPs) by chemical co-precipitation method and obtained Cu doped ZnO-polyvinyl alcohol (PVA) nanocomposite thin films by spin coating to investigate third order nonlinear optical and optical limiting properties under cw laser excitation. Powder samples of NPs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy, transmission electron microscopy, ultraviolet-visible (UV-vis) and Fourier transform infrared spectroscopy. XRD pattern and FE-SEM micrograph revealed the presence of hexagonal wurtzite phase ZnO NPs having uniform morphology with average particle size of 20 nm. The presence of excitons and absorption peaks in the range 343-360 nm, revealed by UV-vis study, were attributed to excitons in n = 1 quantum state. Third order NLO properties of all composite thin films were investigated by He-Ne continuous wave (cw) laser of wavelength 632.8 nm using Z-scan technique. Thermally stimulated enhanced values of nonlinear refraction and absorption coefficients were obtained which may be attributed to self-defocusing effect, reverse saturable absorption, weak free carrier absorption and surface states properties originated from thermo optic effect. Optical limiting properties have been studied using cw diode laser of wavelength 808 nm and results are presented.

  18. Morphology and thermal studies of zinc sulfide and cadmium sulfide nanoparticles in polyvinyl alcohol matrix

    NASA Astrophysics Data System (ADS)

    Osuntokun, Jejenija; Ajibade, Peter A.

    2016-09-01

    Zn(II) and Cd(II) metal complexes of 1-cyano-1-carboethoxyethylene-2,2-dithiolato-κS,S'-bis(N,N-dimethylthiourea-κS) have been synthesized and characterized with analytical and spectroscopic techniques. The complexes were thermolysed in hexadecylamine at 200 °C to prepare ZnS and CdS nanoparticles. The nanoparticles were characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), and powder X-ray diffraction (p-XRD). TEM images showed spherically shaped nanoparticles, whose sizes are in the range 4.33-7.21 nm for ZnS and 4.95-7.7 nm CdS respectively and XRD confirmed cubic crystalline phases for the nanoparticles. The optical band gap energy evaluated from the absorption spectra are 2.88 eV (430 nm) and 2.81 eV (440 nm) for the ZnS and CdS nanoparticles respectively. The as-prepared metal sulfide nanoparticles were further incorporated into polyvinyl alcohol (PVA) to give ZnS/PVA and CdS/PVA composites. The polymer nanocomposites were studied to investigate their morphology and thermal properties relative to the pure PVA. XRD diffractions indicated that the crystalline phases of the nanoparticles and the sizes in PVA matrices remained unaltered. Infra-red spectra studies revealed interactions between the PVA and the metal sulfide nanoparticles and TGA studies show that the ZnS/PVA and CdS/PVA nanocomposites exhibit better thermal stability than the pure PVA.

  19. Effect of Al2O3 on crystallinity and conductivity of PVA-PEO-EC-LiCF3SO3 blend electrolyte system

    NASA Astrophysics Data System (ADS)

    Joge, Prajakta N.; Kanchan, D. K.; Sharma, Poonam L.

    2014-04-01

    In the present study, the PVA-PEO-EC-LiCF3SO3 polymer electrolytes are prepared using solution cast technique for different concentrations of Al2O3 ranging from 2 to 10 wt%. The study deals with the investigation of the influence of Al2O3 concentration on the electrical properties and crystallinity of the polymer electrolytes. The conductivity studies are carried out using impedance spectroscopic analysis and the variation in crystallinity is investigated using XRD technique.

  20. Investigating a new drug delivery nano composite membrane system based on PVA/PCL and PVA/HA(PEG) for the controlled release of biopharmaceuticals for bone infections.

    PubMed

    Wan, Taoyu; Stylios, George K; Giannoudi, Marilena; Giannoudis, Peter V

    2015-12-01

    The capability for sustained and gradual release of pharmaceuticals is a major requirement in the development of a guided antimicrobial bacterial control system for clinical applications. In this study, PVA gels with varying constituents that were manufactured via a refreeze/thawing route, were found to have excellent potential for antimicrobial delivery for bone infections. Cefuroxime Sodium with poly(ethylene glycol) was incorporated into 2 delivery systems poly(e-caprolactone) (PCL) and hydroxyapatite (HA), by a modified emulsion process. Our results indicate that the Cefuroxime Sodium released from poly(e-caprolactone) in PVA was tailored to a sustained release over more than 45 days, while the release from hydroxyapatite PVA reach burst maximum after 20 days. These PVA hydrogel-systems were also capable of controlled and sustained release of other biopharmaceuticals. PMID:26747917

  1. γ-Fe2O3 nanoparticles filled polyvinyl alcohol as potential biomaterial for tissue engineering scaffold.

    PubMed

    Ngadiman, Nor Hasrul Akhmal; Idris, Ani; Irfan, Muhammad; Kurniawan, Denni; Yusof, Noordin Mohd; Nasiri, Rozita

    2015-09-01

    Maghemite (γ-Fe2O3) nanoparticle with its unique magnetic properties is recently known to enhance the cell growth rate. In this study, γ-Fe2O3 is mixed into polyvinyl alcohol (PVA) matrix and then electrospun to form nanofibers. Design of experiments was used to determine the optimum parameter settings for the electrospinning process so as to produce elctrospun mats with the preferred characteristics such as good morphology, Young's modulus and porosity. The input factors of the electrospinnning process were nanoparticles content (1-5%), voltage (25-35 kV), and flow rate (1-3 ml/h) while the responses considered were Young's modulus and porosity. Empirical models for both responses as a function of the input factors were developed and the optimum input factors setting were determined, and found to be at 5% nanoparticle content, 35 kV voltage, and 1 ml/h volume flow rate. The characteristics and performance of the optimum PVA/γ-Fe2O3 nanofiber mats were compared with those of neat PVA nanofiber mats in terms of morphology, thermal properties, and hydrophilicity. The PVA/γ-Fe2O3 nanofiber mats exhibited higher fiber diameter and surface roughness yet similar thermal properties and hydrophilicity compared to neat PVA PVA/γ-Fe2O3 nanofiber mats. Biocompatibility test by exposing the nanofiber mats with human blood cells was performed. In terms of clotting time, the PVA/γ-Fe2O3 nanofibers exhibited similar behavior with neat PVA. The PVA/γ-Fe2O3 nanofibers also showed higher cells proliferation rate when MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was done using human skin fibroblast cells. Thus, the PVA/γ-Fe2O3 electrospun nanofibers can be a promising biomaterial for tissue engineering scaffolds. PMID:26002419

  2. Kinetics and functional effectiveness of nisin loaded antimicrobial packaging film based on chitosan/poly(vinyl alcohol).

    PubMed

    Wang, Hualin; Zhang, Ru; Zhang, Heng; Jiang, Suwei; Liu, Huan; Sun, Min; Jiang, Shaotong

    2015-01-01

    The aim of this study was to evaluate the kinetics and functional effectiveness of Nisin loaded chitosan/poly(vinyl alcohol) (Nisin-CS/PVA) as an antibacterial packaging film. The films were prepared by coating method and Staphylococcus aureus (S. aureus, ATCC6538) was used as test bacterium. The intermolecular hydrogen bonds between CS and PVA molecules were confirmed. The elasticity of films was significantly improved by the incorporation of PVA, and the film could also bear a relative high tensile strength at 26.7 MPa for CS/PVA=1/1. As CS/PVA ratio decreased, the water vapor permeability (WVP) decreased and reached its minimum value 0.983 × 10(-10)gm(-1)s(-1) at CS/PVA=1/1, meanwhile, oxygen permeability (OP) increased but still lower than 0.91 cm(3) μm m(-2)d(-1)kPa(-1) for CS/PVA=1/1 as the CS/PVA ratio was above 1:1. The initial diffusion of nisin (Mt/M ∞ < 2/3) from CS/PVA film could be well described by the Fickian diffusion equation. Owing to the positively charged nisin at pH below isoelectric point (pI, 8.8) and its increasing dissolubility in water as the pH reduced, the diffusion of nisin from the films strongly depended on pH and ionic strength besides CS/PVA ratio and temperature. Moreover, the thermodynamic parameters suggested the spontaneous and endothermic diffusion of nisin from the films. The resulting data can provide some valuable information for the design of film in structure and ingredient. PMID:25965457

  3. Alcohol Alert

    MedlinePlus

    ... Us You are here Home » Alcohol Alert Alcohol Alert The NIAAA Alcohol Alert is a quarterly bulletin that disseminates important research ... text. To order single copies of select Alcohol Alerts, see ordering Information . To view publications in PDF ...

  4. Alcoholism - resources

    MedlinePlus

    Resources - alcoholism ... The following organizations are good resources for information on alcoholism : Alcoholics Anonymous -- www.aa.org Al-Anon/Alateen -- www.al-anon.org/home National Institute on Alcohol ...

  5. Alcoholic ketoacidosis

    MedlinePlus

    Ketoacidosis - alcoholic ... Alcoholic ketoacidosis is caused by very heavy alcohol use. It most often occurs in a malnourished person ... Symptoms of alcoholic ketoacidosis include: Nausea and vomiting ... Changed level of alertness, which may lead to coma Confusion ...

  6. Alcohol Facts

    MedlinePlus

    ... raquo Alcohol Facts Alcohol Facts Listen Drinks like beer, malt liquor, wine, and hard liquor contain alcohol. Alcohol is the ingredient that gets you drunk. Hard liquor—such as whiskey, rum, or gin—has more ...

  7. Alcoholic neuropathy

    MedlinePlus

    Neuropathy - alcoholic; Alcoholic polyneuropathy ... The exact cause of alcoholic neuropathy is unknown. It likely includes both a direct poisoning of the nerve by the alcohol and the effect of poor nutrition ...

  8. Influence of the composition of isopropyl alcohol/water mixture solvents in catalyst ink solutions on proton exchange membrane fuel cell performance

    NASA Astrophysics Data System (ADS)

    Ngo, Trung Truc; Yu, T. Leon; Lin, Hsiu-Li

    2013-03-01

    We study the morphology of Nafion in the dilute IPA (isopropyl alcohol)/water mixture solutions containing 20-100 wt.% of IPA and in the Pt-C/Nafion gas diffusion electrodes (GDEs; where Pt-C is the carbon powder deposited on its surface with Pt particles), which are prepared by spraying on the carbon paper surfaces with a layer of Pt-C, Nafion and IPA/water ink solution. The fuel cell performance of the GDEs strongly depends on the Nafion morphology in the ink solutions. A lower IPA content in the Pt-C/Nafion ink solutions results in the formation of larger and higher negatively charged Nafion aggregated particles, which leads to higher steric hindrance of the deposition of Nafion ionomer on the surface of Pt-C particles and thus a thinner Nafion film in contact on the Pt-C particle surfaces. The thinner Nafion film in contact with the Pt particles in the CL increases the chances of the Pt particles in contact with the H2/O2 gas, leading to a higher fuel cell performance.

  9. Probing the Biomimetic Ice Nucleation Inhibition Activity of Poly(vinyl alcohol) and Comparison to Synthetic and Biological Polymers

    PubMed Central

    2015-01-01

    Nature has evolved many elegant solutions to enable life to flourish at low temperatures by either allowing (tolerance) or preventing (avoidance) ice formation. These processes are typically controlled by ice nucleating proteins or antifreeze proteins, which act to either promote nucleation, prevent nucleation or inhibit ice growth depending on the specific need, respectively. These proteins can be expensive and their mechanisms of action are not understood, limiting their translation, especially into biomedical cryopreservation applications. Here well-defined poly(vinyl alcohol), synthesized by RAFT/MADIX polymerization, is investigated for its ice nucleation inhibition (INI) activity, in contrast to its established ice growth inhibitory properties and compared to other synthetic polymers. It is shown that ice nucleation inhibition activity of PVA has a strong molecular weight dependence; polymers with a degree of polymerization below 200 being an effective inhibitor at just 1 mg.mL–1. Other synthetic and natural polymers, both with and without hydroxyl-functional side chains, showed negligible activity, highlighting the unique ice/water interacting properties of PVA. These findings both aid our understanding of ice nucleation but demonstrate the potential of engineering synthetic polymers as new biomimetics to control ice formation/growth processes PMID:26258729

  10. Synthesis and characterization of a stable dispersion of multifunctional Gd2O3:Er,Yb in polyvinyl alcohol.

    PubMed

    Kaur, Gagandeep; Rai, S B

    2013-01-01

    A stable dispersion of multifunctional Gd2O3:Er,Yb phosphor in polyvinyl alcohol (PVA) was synthesized by varying the concentration of Yb(3+) ions. It had a strong ultraviolet-visible-near infrared (UV-vis) upconversion emission and applications in temperature and magnetic field sensors (e.g., nano-heaters), as well as potential use in bioleveling and bioimaging. Stability of the dispersion was found to strongly depend on the mixing process of the powder in the polymer solution. Spherical shaped nanoparticles in cubic phase of ~ 43 nm diameter were synthesized and characterized by X-ray diffraction; results were confirmed by scanning electron microscopy (SEM). Fourier transform infrared sspectroscopy (FT-IR) and thermal analysis supported the presence of PVA. NIR pumping produced strong UC emission bands in the red and green regions extending up to very high UV (240 nm). This method provides an alternative for synthesizing a highly UC-efficient non-agglomerated pure transparent dispersion from various efficient phosphors for biological applications. PMID:22354467

  11. Preparation and characterization of NaClO4 doped poly(vinyl alcohol)/sodium alginate composite electrolyte

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    The 60:40 wt% poly(vinyl alcohol) (PVA)/sodium alginate blend doped with different concentrations of NaClO4 composite films were prepared by solution casting method. The prepared samples were characterized by FTIR, UV-Vis, DC and AC conductivity. The FTIR spectra confirms the complexation of NaClO4 with host polymer blend. From the UV-Vis spectra, the calculated optical band gap decreases from 5.2eV to 4.6eV. The frequency dependent dielectric constant decreases, and hence the dielectric loss and ac conductivity increases with doping level. The mechanical study shows the Young's modulus, tensile strength, stiffness were increases with the NaClO4 concentrations.

  12. Alcohol Alert: Genetics of Alcoholism

    MedlinePlus

    ... and Reports » Alcohol Alert » Alcohol Alert Number 84 Alcohol Alert Number 84 Print Version The Genetics of ... immune defense system. Genes Encoding Enzymes Involved in Alcohol Breakdown Some of the first genes linked to ...

  13. 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.

  14. Characterizing p-channel thin film transistors using ZnO/hydrated polyvinyl alcohol as the conducting channel

    SciTech Connect

    Liau, Leo Chau-Kuang Hsu, Tzu-Hsien; Lo, Pei-Hsuan

    2014-08-11

    We report the characteristics of p-channel thin film transistors (p-TFTs) with ZnO/hydrated polyvinyl alcohol (PVA) (ZnO/PVA) conducting channels. The metal-oxide-semiconductor structure of the p-TFTs was composed of indium tin oxide (ITO)/SiO{sub 2}/ZnO/PVA layers. The TFT was assembled using PVA gel, which was glued to ITO substrates patterned to form source and drain electrodes. The ZnO/PVA composite film acted as an effective conducting film because of the chemisorption reaction at the film interface where free electrons can be generated. The formation of the conducting channel was also affected by V{sub G} applied to the TFT. The ZnO/PVA-based TFTs demonstrated p-channel transistor performance, shown by current-voltage (I-V) data analysis. The electrical parameters of the device were evaluated, including the on/off ratio (∼10{sup 3}), threshold voltage (V{sub th}, −1 V), and subthreshold swing (−2.2 V/dec). The PVA/ZnO-based p-TFTs were fabricated using simple and cost-effective approaches instead of doping methods.

  15. Combined nitric oxide-releasing poly(vinyl alcohol) film/F127 hydrogel for accelerating wound healing.

    PubMed

    Schanuel, Fernanda Seabra; Raggio Santos, Karen Slis; Monte-Alto-Costa, Andréa; de Oliveira, Marcelo G

    2015-06-01

    Nitric oxide (NO) releasing biomaterials represent a potential strategy for use as active wound dressings capable of accelerating wound healing. Topical NO-releasing poly(vinyl alcohol) (PVA) films and Pluronic F127 hydrogels (F127) have already exhibited effective skin vasodilation and wound healing actions. In this study, we functionalized PVA films with SNO groups via esterification with a mixture of mercaptosucinic acid (MSA) and thiolactic acid (TLA) followed by S-nitrosation of the SH moieties. These films were combined with an underlying layer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide), i.e., PEO-PPO-PEO (Pluronic F127) hydrogel and used for the topical treatment of skin lesions in an animal model. The mixed esterification of PVA with MSA and TLA led to chemically crosslinked PVA-SNO films with a high swelling capacity capable of spontaneously releasing NO. Real time NO-release measurements revealed that the hydrogel layer reduces the initial NO burst from the PVA-SNO films. We demonstrate that the combination of PVA-SNO films with F127 hydrogel accelerates wound contraction, decreases wound gap and cellular density and accelerates the inflammatory phase of the lesion. These results were reflected in an increase in myofibroblastic differentiation and collagen type III expression in the cicatricial tissue. Therefore, PVA-SNO films combined with F127 hydrogel may represent a new approach for active wound dressings capable of accelerating wound healing. PMID:25907598

  16. Highly conductive quasi-coaxial electrospun quaternized polyvinyl alcohol nanofibers and composite as high-performance solid electrolytes

    NASA Astrophysics Data System (ADS)

    Liao, Guan-Ming; Li, Pin-Chieh; Lin, Jia-Shiun; Ma, Wei-Ting; Yu, Bor-Chern; Li, Hsieh-Yu; Liu, Ying-Ling; Yang, Chun-Chen; Shih, Chao-Ming; Lue, Shingjiang Jessie

    2016-02-01

    Electrospun quaternized polyvinyl alcohol (Q-PVA) nanofibers are prepared, and a potassium hydroxide (KOH)-doped nanofiber mat demonstrates enhanced ionic conductivity compared with a dense Q-PVA film with KOH doping. The Q-PVA composite containing 5.98% electrospun Q-PVA nanofibers exhibits suppressed methanol permeability. Both the high conductivity and suppressed methanol permeability are attributed to the quasi-coaxial structure of the electrospun nanofibers. The core of the fibers exhibits a more amorphous region that forms highly conductive paths, while the outer shell of the nanofibers contains more polymer crystals that serve as a hard sheath surrounding the soft core. This shell induces mass transfer resistance and creates a tortuous fuel pathway that suppresses methanol permeation. Such a Q-PVA composite is an effective solid electrolyte that makes the use of alkaline fuel cells viable. In a direct methanol alkaline fuel cell operated at 60 °C, a peak power density of 54 mW cm-2 is obtained using the electrospun Q-PVA composite, a 36.4% increase compared with a cell employing a pristine Q-PVA film. These results demonstrate that highly conductive coaxial electrospun nanofibers can be prepared through a single-opening spinneret and provide a possible approach for high-performance electrolyte fabrication.

  17. Glutaraldehyde-chitosan and poly (vinyl alcohol) blends, and fluorescence of their nano-silica composite films.

    PubMed

    Hu, Huawen; Xin, John H; Hu, Hong; Chan, Allan; He, Liang

    2013-01-01

    In this study, a commercial chitosan cross-linked with glutaraldehyde (GA-chitosan) having the autofluorescent property was effectively blended with a poly (vinyl alcohol) (PVA) matrix, in the formation of a transparent and fluorescent blend film. The fluorescent efficiency of the film was enhanced with red-shifted emission band by increasing the concentrations of the GA-chitosan and decreasing the PVA crystallinity. It was found that the incorporation of silica nanoparticles could further decrease the PVA crystallinity, enhance the fluorescent efficiency, and largely redshift the emission band, as compared with the neat GA-chitosan-PVA blend film. This fluorescent property could be finely tuned by careful doping of the silica nanoparticles and change of the PVA crystallinity. These phenomena could be reasonably explained by high extent of isolation of the fluorophores, increase of the stiffness of the fluorescent conjugated planar structure, and further decrease of the PVA crystallinity. In addition, the introduction of the nano-silica could improve the water and heat resistances of the GA-chitosan-PVA based silica nanocomposites. PMID:23044137

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

    PubMed Central

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

    2011-01-01

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

  19. Multifunctional necklace-like Cu@cross-linked poly(vinyl alcohol) microcables with fluorescent property and their manipulation by an external magnet.

    PubMed

    Zhang, Sen; Zhu, Hui-Yuan; Hu, Zhi-Bin; Liu, Lu; Chen, Shao-Feng; Yu, Shu-Hong

    2009-05-01

    Unique magnetite-nanoparticles-attached necklace-like Cu@cross-linked poly(vinyl alcohol) (PVA) microcables with multi-functionalities can be synthesized by in situ loading the magnetite nanoparticles in the network structure of a cross-linked PVA sheath using a modified polyol method; the superparamagnetic and green fluorescent properties of the cables enable this type of magnetic functionalized microcables to be manipulated and detected easily for device fabrication. PMID:19377674

  20. Efficiency of barium removal from radioactive waste water using the combination of maghemite and titania nanoparticles in PVA and alginate beads.

    PubMed

    Majidnia, Zohreh; Idris, Ani; Majid, MuhdZaimiAbd; Zin, RosliMohamad; Ponraj, Mohanadoss

    2015-11-01

    In this paper, both maghemite (γ-Fe2O3) and titanium oxide (TiO2) nanoparticles were synthesized and mixed in various ratios and embedded in PVA and alginate beads. Batch sorption experiments were applied for removal of barium ions from aqueous solution under sunlight using the beads. The process has been investigated as a function of pH, contact time, temperature, initial barium ion concentration and TiO2:γ-Fe2O3 ratios (1:10, 1:60 and 1). The recycling attributes of these beads were also considered. Furthermore, the results revealed that 99% of the Ba(II) was eliminated in 150min at pH 8 under sunlight. Also, the maghemite and titania PVA-alginate beads can be readily isolated from the aqueous solution after the process and reused for at least 7 times without significant losses of their initial properties. The reduction of Ba(II) with maghemite and titania PVA-alginate beads fitted the pseudo first order and second order Langmuir-Hinshelwood (L-H) kinetic model. PMID:26275818