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Sample records for polyvinylpyrrolidone ultrafine fibers

  1. Ultrafine PBI fibers and yarns

    NASA Technical Reports Server (NTRS)

    Leal, J. R.; Tan, M.

    1979-01-01

    Gentle precisely controlled process is used to draw polybenzimidazole (PBI) fibers to denier as low as 0.17 per fiber. Yarns of lightweight fibers could be useful in applications where lightweight textiles must withstand high temperatures, corrosion, or radiation.

  2. Ultrafine particle and fiber production in microgravity

    NASA Technical Reports Server (NTRS)

    Webb, George W. (Inventor)

    1988-01-01

    In a system and method for producing ultrafine particles and ultrafine fibers of a given source material by evaporating and condensing the material in a gas atmosphere that includes inert gas. A smaller, more narrow size distribution is accomplished by producing the particles and fibers in a microgravity environment in order to reduce particle coalescence caused by convection currents. Particle coalescence also is reduced in an Earth gravity environment by controlling the convection currents. Condensed particles are collected either by providing an electrostatic field or a spatially varying magnetic field or by causing the gas to move through a filter which collects the particles. Nonferromagnetic material fibers are produced and collected by electrodes which produce an electro- static field. Ferromagnetic particles are collected by spatially varying magnetic fields.

  3. Cytocompatible and water stable ultrafine protein fibers for tissue engineering

    NASA Astrophysics Data System (ADS)

    Jiang, Qiuran

    This dissertation proposal focuses on the development of cytocompatible and water stable protein ultrafine fibers for tissue engineering. The protein-based ultrafine fibers have the potential to be used for biomedicine, due to their biocompatibility, biodegradability, similarity to natural extracellular matrix (ECM) in physical structure and chemical composition, and superior adsorption properties due to their high surface to volume ratio. However, the current technologies to produce the protein-based ultrafine fibers for biomedical applications still have several problems. For instance, the current electrospinning and phase separation technologies generate scaffolds composed of densely compacted ultrafine fibers, and cells can spread just on the surface of the fiber bulk, and hardly penetrate into the inner sections of scaffolds. Thus, these scaffolds can merely emulate the ECM as a two dimensional basement membrane, but are difficult to mimic the three dimensional ECM stroma. Moreover, the protein-based ultrafine fibers do not possess sufficient water stability and strength for biomedical applications, and need modifications such as crosslinking. However, current crosslinking methods are either high in toxicity or low in crosslinking efficiency. To solve the problems mentioned above, zein, collagen, and gelatin were selected as the raw materials to represent plant proteins, animal proteins, and denatured proteins in this dissertation. A benign solvent system was developed specifically for the fabrication of collagen ultrafine fibers. In addition, the gelatin scaffolds with a loose fibrous structure, high cell-accessibility and cell viability were produced by a novel ultralow concentration phase separation method aiming to simulate the structure of three dimensional (3D) ECM stroma. Non-toxic crosslinking methods using citric acid as the crosslinker were also developed for electrospun or phase separated scaffolds from these three proteins, and proved to be

  4. Development of ultrafine polyester fiber vascular grafts with high endothelialization capability. Angiogenesis by ultrafine polyester fibers.

    PubMed

    Niu, S; Satoh, S; Shirakata, S; Oka, T; Noishiki, Y; Kurumatani, H; Watanabe, K

    1989-01-01

    The authors previously showed that a vascular prosthesis made of ultrafine polyester fibers (UFPF) had high healing ability even when of low porosity. In this study, new highly porous vascular grafts fabricated from UFPF (water porosity: 3,600 ml/min/cm2, 8 mm in inner diameter and 5 cm in length), were developed and implanted in the thoracic descending aorta of dogs to evaluate their endothelialization capability. Two weeks after implantation, many colonies of endothelial cells with openings of capillary blood vessels were noted, even in the middle portion of the grafts. Numerous fibroblasts and capillary blood vessels were also observed in the synthetic walls. These results suggest that UFPF vascular grafts provide a suitable microenvironment for infiltration and proliferation of fibroblasts, which are accompanied by the capillary formation as nutrient supply; these capillaries provide multiple sources of endothelial coverage on the luminal surface. It is expected that the new, highly porous vascular grafts may have rich endothelialization capability and stable healing properties in humans. PMID:2480800

  5. Mesosilica-coated ultrafine fibers for highly efficient laccase encapsulation

    NASA Astrophysics Data System (ADS)

    Wang, Shiwen; Chen, Wei; He, Sha; Zhao, Qilong; Li, Xiaohong; Sun, Jiashu; Jiang, Xingyu

    2014-05-01

    In this paper, we present a simple but efficient biomimetic method to encapsulate laccase on mesoporous silica-modified electrospun (ES) ultrafine fibers. Because of the mild immobilization conditions (room temperature, aqueous condition), the encapsulated laccase retained a high activity of 94%. Because of the protection from the silica layer, the laccase worked efficiently at 60 °C and retained a long-term activity in the presence of proteinase K. After recycling for 10 times the laccase still preserved 96% of its original reactivity. More remarkably, the immobilized laccase on fibers could completely recover its activity after thermal denature, while the free laccase permanently lost the activity. We also demonstrated that the laccase on silica-coated fibers exhibited an enhanced decolorization capability of Brilliant Blue KN-R (BBKN-R) as compared to the free laccase, showing its great potential for industrial applications.In this paper, we present a simple but efficient biomimetic method to encapsulate laccase on mesoporous silica-modified electrospun (ES) ultrafine fibers. Because of the mild immobilization conditions (room temperature, aqueous condition), the encapsulated laccase retained a high activity of 94%. Because of the protection from the silica layer, the laccase worked efficiently at 60 °C and retained a long-term activity in the presence of proteinase K. After recycling for 10 times the laccase still preserved 96% of its original reactivity. More remarkably, the immobilized laccase on fibers could completely recover its activity after thermal denature, while the free laccase permanently lost the activity. We also demonstrated that the laccase on silica-coated fibers exhibited an enhanced decolorization capability of Brilliant Blue KN-R (BBKN-R) as compared to the free laccase, showing its great potential for industrial applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr01166j

  6. Clinical use of low porosity woven ultrafine polyester fiber grafts.

    PubMed

    Satoh, S; Niu, S; Kanda, K; Hirai, J; Nakazima, S; Wada, Y; Oka, T; Noishiki, Y

    1995-01-01

    A woven fabric graft made of ultrafine polyester fibers (UFPF) (Toray Graft, water porosity: 100 ml/min/cm2:120 mm Hg H2O) was clinically applied in 81 cases (28 thoracic aortic aneurysms, 6 thoracoabdominal aortic aneurysms, 42 abdominal aortic aneurysms, and 5 atherosclerotic obstructions of the peripheral arteries). Eight patients died after surgery due to causes unrelated to the graft. The other 73 patients were in good condition after surgery. For operations requiring extracorporeal circulation, the graft was presealed with human albumin. For the abdominal aortic aneurysms, the graft was preclotted in situ with nonheparinized autoblood after the completion of the proximal anastomosis. It took about 2 min to complete the preclotting. A nonsealed graft was used for the reconstruction of peripheral arteries for the intraaortic balloon pumping procedure. The graft was easy to handle. There was no cut edge fraying problem with the graft in any direction of cutting. Even after presealing, the graft was soft and pliable enough to enable easy adaptation and anastomosis. Just after implantation, bleeding was minimal from the graft wall, anastomotic sites, and suture pores, and it stopped spontaneously. These clinical data showed that the woven UFPF graft exhibited both easy handling despite in spite of low porosity and safe application in the reconstruction of arterial systems even under totally heparinized conditions during extracorporeal circulation. PMID:7741640

  7. Antimicrobial Activity of Ultra-fine Fiber Nonwoven Fabrics Produced by Electrospinning

    NASA Astrophysics Data System (ADS)

    Ogushi, Yukiko; Sasaki, Naokazu; Imashiro, Yasuo; Minagawa, Mie; Matsumoto, Hidetoshi; Tanioka, Akihiko

    Electrospinning is based on an electrohydrodynamic process, and it is a straightforward and versatile method for forming continuous thin fibers from several nanometers to several tens of micrometers in diameter. One major advantage of electrospinning is the one-step forming of nonwoven fibrous fabrics. In the present study, we prepared ultra-fine fiber nonwoven fabrics from 13 kinds of commercial polymers (e.g., PLA, PA, PU, Cellulose, PVDC, and PS) by electrospinning and tested their antimicrobial activity. Most of ultra-fine fiber nonwoven fabrics showed excellent antimicrobial activity. Our experimental results showed that there is close correlation between fiber diameter of nonwoven fabrics and their antimicrobial activity: the nonwoven fabrics with average fiber diameter of smaller than 800 nm showed better antimicrobial activity.

  8. Fabrication, gastromucoadhesivity, swelling, and degradation of zein-chitosan composite ultrafine fibers.

    PubMed

    Wongsasulak, Saowakon; Puttipaiboon, Natthon; Yoovidhya, Tipaporn

    2013-06-01

    Fabrication, via electrospinning, and characterization of an ultrafine structure architected from a blend of hydrophobic zein and hydrophilic chitosan (CS) were conducted. Poly(ethylene oxide) (PEO) and nonionic surfactant, namely, Tween 40, were employed to improve the electrospinnability of the blend, while ethanol was used as a solvent for zein. The effects of ethanol (EtOH) concentration (85% and 90%) and ratio of zein/PEO/CS (95/2.5/2.5 and 87.5/10/2.5) on the fiber morphology as well as gastromucoadhesivity against porcine stomach mucosa were then investigated; polymer-mucosa adhesion was also investigated via Fourier-transform infrared spectroscopy. Swelling and degradation of the composite ultrafine fibers were investigated under 2 simulated gastric conditions, namely, at pH 2 without pepsin and at pH 1.2 with pepsin. Using 85% EtOH as a solvent for zein resulted in a spider-web-like morphology; the maximum detachment force (MDF), which is an indirect indicator of the gastromucoadhesivity was nevertheless higher. Zein-based ultrafine fibers exhibited higher MDF than the zein-PEO-CS composite; however, the cohesiveness of the composite fibers was higher. FTIR spectroscopic results indicated molecular interactions between the composite fibers and mucin functional groups. Swelling of the composite ultrafine fibers in simulated gastric fluid (SGF) at pH 2 without pepsin was not different from that in SGF at pH 1.2 with pepsin. Nevertheless, degradation of the composite fibers in SGF at pH 2 without pepsin was much less than that in SGF at pH 1.2 with pepsin; only 20% degradation was noted in the former case. PMID:23627787

  9. Facile fabrication of gold nanoparticle on zein ultrafine fibers and their application for catechol biosensor

    NASA Astrophysics Data System (ADS)

    Chen, Xiaodong; Li, Dawei; Li, Guohui; Luo, Lei; Ullah, Naseeb; Wei, Qufu; Huang, Fenglin

    2015-02-01

    A novel laccase biosensor based on a new composite of laccase-gold nanoparticles (Au NPs)-crosslinked zein ultrafine fibers (CZUF) has been fabricated for catechol determination in real solution samples. Firstly, crosslinked zein ultrafine fibers containing gold nanoparticles (A-CZUF) were prepared by combining electrospinning and one-step reduction method using poly(ethyleneimine) (PEI) as reducing and crosslinking agent. A smooth morphology and relative average distribution of A-CZUF were depicted by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The Fourier transform infrared spectroscopy (FT-IR) analysis indicated that PEI molecules attached to the surface of the zein ultrafine fibers via the reaction of functional groups between PEI and glyoxal. The results obtained from ultraviolet visible spectroscopy (UV-vis spectroscopy), X-ray diffraction (XRD) and thermal gravimetric analysis (TGA) for A-CZUF confirmed the existence of Au NPS coated on the surface of CZUF. Square wave voltammetry (SWV) and cyclic voltammetry (CV) were used to detect the electrochemical performance of the proposed biosensor. The results demonstrated that this biosensor possessed a high sensitive detection to catechol, which was attributed to the direct electron transfer (DET) facilitated by Au NPs and high catalytic ability obtained from laccase. In addition, the proposed biosensor exhibited good reproducibility, stability and selectivity.

  10. The preparation and characterization of highly aligned poly(epsilon-caprolactone)/poly ethylene oxide/chitosan ultrafine fiber for the application to tissue scaffold.

    PubMed

    Nien, Yu-Hsun; Wang, Jia-Yi; Tsai, Yan-Sheng

    2013-07-01

    The purpose of this study was to fabricate poly(epsilon-caprolactone) (PCL)/poly ethylene oxid (PEO)/chitosan (CS) ultrafine fiber in both aligned and random structures using electrospinning technique and their process parameters were optimized. The aligned and random PCL/PEO/chitosan ultrafine fibers were also used as scaffold for tissue engineering and their cell affinity was investigated. In the first part, we inspected the effect of environment conditions, solution properties, process parameters on PCL/PEO/chitosan ultrafine fiber. In the second part, the apparatus of electrospinning to manufacture highly aligned PCL/PEO/chitosan ultrafine fiber was developed. The effects of process parameters such as flow rate, design of collector and rotation speed of collecting drum on the morphology of ultrafine fiber were discussed. In addition, the cross link of PCL/PEO/chitosan ultrafine fiber by cross-linking agent was examined, too. The physical properties, chemical properties, and cell affinities of the aligned PCL/PEO/chitosan ultrafine fiber with or without cross link were measured. The chemical analysis and tensile strength of the ultrafine fiber were characterized using Fourier Transfer Infared Spectrophotometer and Universal Tensile Machine, respectively. The results show that the aligned PCL/PEO/chitosan ultrafine fibrous mat had the capacity to induce cellular alignment and enhance cellular elongation. PMID:23901493

  11. Mechanical and electrical properties of electrospun PVDF/MWCNT ultrafine fibers using rotating collector

    PubMed Central

    2014-01-01

    Poly(vinylidene fluoride) (PVDF) ultrafine fibers with different proportions of multi-walled carbon nanotube (MWCNT) embedded have been fabricated using a modified electrospinning device with a rotating collector. With the increasing of MWCNT content, the β phase was noticeable enhanced, and the fibers became more elastic, which was manifested by Young's modulus decreased drastically. Furthermore, with adding the amounts of MWCNTs, the density of carbon nanotube (CNT)-CNT junctions among the fibers increased accordingly. When the MWCNT content was of 1.2 wt.%, a stable three-dimensional conducting network was formed. After this percolation threshold, the density of CNT-CNT junctions among the fibers tended to be a constant quantity, leading to a stabilized conductivity consequently. It is hoped that our results can be helpful for the fabrication of flexible devices, piezoelectric devices, force transducer, and so on. PACS 81.05.Qk; 81.16.-c PMID:25288915

  12. Mechanistic insights into formation of SnO₂ nanotubes: asynchronous decomposition of poly(vinylpyrrolidone) in electrospun fibers during calcining process.

    PubMed

    Wu, Jinjin; Zeng, Dawen; Wang, Xiaoxia; Zeng, Lei; Huang, Qingwu; Tang, Gen; Xie, Changsheng

    2014-09-23

    The formation mechanism of SnO2 nanotubes (NTs) fabricated by generic electrospinning and calcining was revealed by systematically investigating the structural evolution of calcined fibers, product composition, and released volatile byproducts. The structural evolution of the fibers proceeded sequentially from dense fiber to wire-in-tube to nanotube. This remarkable structural evolution indicated a disparate thermal decomposition of poly(vinylpyrrolidone) (PVP) in the interior and the surface of the fibers. PVP on the surface of the outer fibers decomposed completely at a lower temperature (<340 °C), due to exposure to oxygen, and SnO2 crystallized and formed a shell on the fiber. Interior PVP of the fiber was prone to loss of side substituents due to the oxygen-deficient decomposition, leaving only the carbon main chain. The rest of the Sn crystallized when the pores formed resulting from the aggregation of SnO2 nanocrystals in the shell. The residual carbon chain did not decompose completely at temperatures less than 550 °C. We proposed a PVP-assisted Ostwald ripening mechanism for the formation of SnO2 NTs. This work directs the fabrication of diverse nanostructure metal oxide by generic electrospinning method. PMID:25162977

  13. Effect of ultrafine poly(ε-caprolactone) fibers on calcium phosphate cement: in vitro degradation and in vivo regeneration

    PubMed Central

    Yang, Boyuan; Zuo, Yi; Zou, Qin; Li, Limei; Li, Jidong; Man, Yi; Li, Yubao

    2016-01-01

    We incorporated ultrafine polymer fibers into calcium phosphate cement (CPC) to improve the resorption rate of CPC with fiber degradation. Different weight percentages of electrospun poly(ε-caprolactone) fibers (0%, 3%, and 7%, named as ultrafine fiber-incorporated CPC0 [UFICPC0], UFICPC3, and UFICPC7) were included into preset CPC specimens for in vitro immersion in lipase phosphate-buffered solution and long-term in vivo implantation in the femoral condyle of rabbits. The effect of the ultrafine poly(ε-caprolactone) fibers with a diameter ranging from nanometer to micrometer on CPC degradation was evaluated by measuring the pH of the medium, mass loss, porosity, and physiochemical properties. For the in vivo evaluation, histomorphometrical analysis as well as three-dimensional (3D) reconstruction was applied to assess the osteogenic properties of the CPC composite. After in vitro immersion and in vivo implantation, the total porosity and macroporosity as well as the bone formation and ingrowth increased significantly during time in the fiber-incorporated CPC specimens. After 24 weeks of implantation, the degraded space was occupied by newly formed bone, and the UFICPC3 and UFICPC7 composites showed ~3.5 times higher fraction of bone volume than that of the pristine CPC (UFICPC0). In vitro and in vivo results proved that the introduction of ultrafine degradable fibers within a CPC matrix can be used to improve macroporosity efficiently and enhance CPC degradation and bone ingrowth largely. PMID:26792992

  14. Preparation of silica-sustained electrospun polyvinylpyrrolidone fibers with uniform mesopores via oxidative removal of template molecules by H{sub 2}O{sub 2} treatment

    SciTech Connect

    Kang, Haigang; Zhu, Yihua; Shen, Jianhua; Yang, Xiaoling; Chen, Cheng; Cao, Huimin; Li, Chungzhong

    2010-07-15

    Silica-sustained electrospun PVP fibers with uniform mesopores were synthesized via facile oxidative removal of template molecules by H{sub 2}O{sub 2} extraction. Tetraethyl orthosilicate, polyvinylpyrrolidone (PVP), and triblock poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) copolymer pluronic P{sub 123} compose the electrospinning sol to fabricate the silica-sustained PVP hybrid fibers. The effect of different post-treatment methods on the pore size distribution was investigated by calcination and extraction, respectively. Experimental results showed that oxidative removal of structure-directing agent P{sub 123} in the hybrid fibers by H{sub 2}O{sub 2} treatment can easily form narrow pore size distribution, and the incorporation of 3D silica skeleton built by hot steam aging facilitated preserving the original cylindrical morphology of fibers. Scanning electron microscopy (SEM), N{sub 2} adsorption-desorption isotherm, transmission electron microscopy (TEM), X-ray diffraction (XRD), FT-IR spectra and thermogravimetric analysis (TGA) were used to characterize the hybrid fibers. The hybrid fibers can be expected to have potential applications in drug release or tissue engineering because of their suitable pore size, large surface area and good biocompatibility.

  15. Preparation and evaluation of magnetic nanocomposite fibers containing α″-Fe₁₆N₂ and α-Fe nanoparticles in polyvinylpyrrolidone via magneto-electrospinning.

    PubMed

    Kartikowati, Christina W; Suhendi, Asep; Zulhijah, Rizka; Ogi, Takashi; Iwaki, Toru; Okuyama, Kikuo

    2016-01-15

    Two kinds of ferromagnetic nanocomposite fiber comprising α″-Fe16N2 and α-Fe nanoparticles (NPs), which have the highest magnetic moments as hard and soft magnetic materials, respectively, embedded in polyvinylpyrrolidone (PVP) have been synthesized via the magneto-electrospinning method. Both α″-Fe16N2 and α-Fe were single-domain core-shell NPs with an average outer diameter of 50 nm and Al2O3 as the shell. Ferrofluid precursors used for the electrospinning were prepared by dispersing these NPs in a PVP-toluene-methanol solution. The results show that applying the magnetic field in the same direction as the electric field resulted in smaller and more uniform fiber diameters. Nanocomposite fibers containing α″-Fe16N2 had smaller diameters than those containing α-Fe NPs. These magnetic-field effects on the fiber formation were explained by referring to the kinetic energy of the moving jet in the electrospinning process. In addition, magnetic hysteresis curves showed an enhancement of the magnetic coercivity (H(c)) and remanence (M(r)) by 22.9% and 22.25%, respectively. These results imply a promising possibility of constructing bulk magnetic materials using α″-Fe16N2 NPs, which furthermore reveals attractive features for many other magnetic applications, such as magnetic sensors. PMID:26618712

  16. Preparation and evaluation of magnetic nanocomposite fibers containing α″-Fe16N2 and α-Fe nanoparticles in polyvinylpyrrolidone via magneto-electrospinning

    NASA Astrophysics Data System (ADS)

    Kartikowati, Christina W.; Suhendi, Asep; Zulhijah, Rizka; Ogi, Takashi; Iwaki, Toru; Okuyama, Kikuo

    2016-01-01

    Two kinds of ferromagnetic nanocomposite fiber comprising α″-Fe16N2 and α-Fe nanoparticles (NPs), which have the highest magnetic moments as hard and soft magnetic materials, respectively, embedded in polyvinylpyrrolidone (PVP) have been synthesized via the magneto-electrospinning method. Both α″-Fe16N2 and α-Fe were single-domain core-shell NPs with an average outer diameter of 50 nm and Al2O3 as the shell. Ferrofluid precursors used for the electrospinning were prepared by dispersing these NPs in a PVP-toluene-methanol solution. The results show that applying the magnetic field in the same direction as the electric field resulted in smaller and more uniform fiber diameters. Nanocomposite fibers containing α″-Fe16N2 had smaller diameters than those containing α-Fe NPs. These magnetic-field effects on the fiber formation were explained by referring to the kinetic energy of the moving jet in the electrospinning process. In addition, magnetic hysteresis curves showed an enhancement of the magnetic coercivity (H c) and remanence (M r) by 22.9% and 22.25%, respectively. These results imply a promising possibility of constructing bulk magnetic materials using α″-Fe16N2 NPs, which furthermore reveals attractive features for many other magnetic applications, such as magnetic sensors.

  17. Ultrafine polybenzimidazole (PBI) fibers. [separators for alkaline batteries and dfuel cells

    NASA Technical Reports Server (NTRS)

    Chenevey, E. C.

    1979-01-01

    Mats were made from ultrafine polybenzimidazole (PBI) fibers to provide an alternate to the use of asbestos as separators in fuel cells and alkaline batteries. To minimize distortion during mat drying, a process to provide a dry fibrid was developed. Two fibrid types were developed: one coarse, making mats for battery separators; the other fine, making low permeability matrices for fuel cells. Eventually, it was demonstrated that suitable mat fabrication techniques yielded fuel cell separators from the coarser alkaline battery fibrids. The stability of PBI mats to 45% KOH at 123 C can be increased by heat treatment at high temperatures. Weight loss data to 1000 hours exposure show the alkali resistance of the mats to be superior to that of asbestos.

  18. Vegetation collection efficiency of ultrafine particles: From single fiber to porous media

    NASA Astrophysics Data System (ADS)

    Lin, Ming-Yeng; Khlystov, Andrey; Katul, Gabriel G.

    2014-01-01

    A number of parameterization schemes are available to determine the collection efficiency of ultrafine particles (UFP) onto vegetated surfaces. One approach represents the vegetated elements as a fibrous filter with a characteristic fiber size that is difficult to a priori determine, while the other, a more conventional approach, represents vegetation as a porous medium. To date, no attempts have been made to compare the performance of these two distinct approaches or bridge them so as to show the necessary conditions leading to their potential equivalence. In a wind tunnel study, the UFP collection efficiencies of pine branches at five different wind speeds, two branch orientations, and two packing densities were measured and analyzed using these two vegetation representations. This vegetation type was selected because pines are a dominant species in the Southeastern United States and pine needles geometrically resemble fibrous material with a well-defined foliage diameter. The porous media and the fibrous filter representations described well observed UFP deposition at the branch scale. Conditions promoting their equivalence are thus explored. The difficult to determine effective fiber diameter was recovered from conventional canopy attributes such as the leaf area index by matching the collection efficiencies of UFP for the two vegetation representations. These results provide a working "aerodynamic" definition of the effective single-fiber diameter thereby rendering the simplified single-fiber formulation usable in large-scale atmospheric deposition models. Furthermore, the aerodynamic correction factor allows upscaling of pine needles to an effective leaf area index and provides some quantification of the effect of needle spatial clustering on UFP deposition. The applicability of the results to other vegetation species remains to be verified.

  19. [Clinical experiences of a new vascular graft prosthesis fabricated from ultrafine polyester fiber (Toray graft)].

    PubMed

    Hashimoto, A; Aomi, S; Koyanagi, H

    1992-11-01

    A new low porous vascular prosthesis made of a textile of ultra-fine fiber was used clinically in ten patients for whom replacement of the ascending and/or arch aorta were performed. There were no operative deaths after initial operations, but one patient died after a second operation in which replacement of the thoraco-abdominal aorta was performed. Nine survived patients are well for 50 days to 10 months postoperatively. The new vascular graft prosthesis was very soft and pliable in clinical use, and the surgical needle penetrates easily the prosthesis. Although the new graft prosthesis can be used without preclotting under full heparinization, porosity of the graft, 100 ml/min/cm, revealed initial oozing of blood for a while just after releasing an aortic clamp. Therefore, preclotting of the graft is recommended under full heparinization. Because of rapid, even, and stable formation of neo-intima in the new graft confirmed by experimental studies of Noishiki et al., and soft and pliable characteristics of the graft, a wide-spread clinical use of the new graft is recommended in the surgery of aortic aneurysms as well as reconstruction of the congenital malformations. PMID:1405126

  20. Ultrafine Au and Ag Nanoparticles Synthesized from Self-Assembled Peptide Fibers and Their Excellent Catalytic Activity.

    PubMed

    Xu, Wenlong; Hong, Yue; Hu, Yuanyuan; Hao, Jingcheng; Song, Aixin

    2016-07-18

    The self-assembly of an amphiphilic peptide molecule to form nanofibers facilitated by Ag(+) ions was investigated. Ultrafine AgNPs (NPs=nanoparticles) with an average size of 1.67 nm were synthesized in situ along the fibers due to the weak reducibility of the -SH group on the peptide molecule. By adding NaBH4 to the peptide solution, ultrafine AgNPs and AuNPs were synthesized with an average size of 1.35 and 1.18 nm, respectively. The AuNPs, AgNPs, and AgNPs/nanofibers all exhibited excellent catalytic activity toward the reduction of 4-nitrophenol, with turnover frequency (TOF) values of 720, 188, and 96 h(-1) , respectively. Three dyes were selected for catalytic degradation by the prepared nanoparticles and the nanoparticles showed selective catalysis activity toward the different dyes. It was a surprising discovery that the ultrafine AuNPs in this work had an extremely high catalytic activity toward methylene blue, with a reaction rate constant of 0.21 s(-1) and a TOF value of 1899 h(-1) . PMID:27028550

  1. 21 CFR 173.55 - Polyvinylpyrrolidone.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyvinylpyrrolidone. 173.55 Section 173.55 Food... for Food Treatment § 173.55 Polyvinylpyrrolidone. The food additive polyvinylpyrroli-done may be... maximum unsaturation of 1 percent, calculated as the monomer, except that the polyvinylpyrrolidone used...

  2. Morphology of Nano and Micro Fiber Structures in Ultrafine Particles Filtration

    SciTech Connect

    Kimmer, Dusan; Vincent, Ivo; Fenyk, Jan; Petras, David; Zatloukal, Martin; Sambaer, Wannes; Zdimal, Vladimir

    2011-07-15

    Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres, space polycarbonate nanostructures having bead spacers, structures formed by a combination of polymethyl methacrylate micro- and nanofibres and polypropylene meltblown microstructures, through which ultrafine particles of ammonium sulphate 20-400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free volume fraction as flat nanofibre filters but an increased effective fibre surface area, changed pore size morphology and, consequently, a higher filter quality.

  3. Electrospun Ultrafine Fiber Composites Containing Fumed Silica: From Solution Rheology to Materials with Tunable Wetting.

    PubMed

    Dufficy, Martin K; Geiger, Mackenzie T; Bonino, Christopher A; Khan, Saad A

    2015-11-17

    Fumed silica (FS) particles with hydrophobic (R805) or hydrophilic (A150) surface functionalities are incorporated in polyacrylonitrile (PAN) fibers by electrospinning to produce mats with controlled wettability. Rheological measurements are conducted to elucidate the particle-polymer interactions and characterize the system while microscopic and analytic tools are used to examine FS location within both fibers and films to aid in the fundamental understanding of wetting behavior. Unlike traditional polymers, we find these systems to be gel-like, yet electrospinnable; the fumed silica networks break down into smaller aggregates during the electrospinning process and disperse both within and on the surface of the fibers. Composite nanofiber mats containing R805 FS exhibit an apparent contact angle over 130° and remain hydrophobic over 30 min, while similar mats with A150 display rapid surface-wetting with a static contact angle of ∼30°. Wicking experiments reveal that the water absorption properties can be further manipulated, with R805 FS-impregnated mats taking up only 8% water relative to mat weight in 15 min. In contrast, PAN fibers containing A150 FS absorb 425% of water in the same period, even more than the pure PAN fiber (371%). The vastly different responses to water demonstrate the versatility of FS in surface modification, especially for submicron fibrous mats. The role of fumed silica in controlling wettability is discussed in terms of their surface functionality, placement on nanofibers and induced surface roughness. PMID:26477547

  4. 21 CFR 173.55 - Polyvinylpyrrolidone.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Polyvinylpyrrolidone. 173.55 Section 173.55 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.55 Polyvinylpyrrolidone. The food... the polyvinylpyrrolidone used in beer is that having an average molecular weight of 360,000 and...

  5. 21 CFR 173.55 - Polyvinylpyrrolidone.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Polyvinylpyrrolidone. 173.55 Section 173.55 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.55 Polyvinylpyrrolidone. The food... the polyvinylpyrrolidone used in beer is that having an average molecular weight of 360,000 and...

  6. 21 CFR 173.55 - Polyvinylpyrrolidone.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Polyvinylpyrrolidone. 173.55 Section 173.55 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.55 Polyvinylpyrrolidone. The food... the polyvinylpyrrolidone used in beer is that having an average molecular weight of 360,000 and...

  7. 21 CFR 173.55 - Polyvinylpyrrolidone.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Polyvinylpyrrolidone. 173.55 Section 173.55 Food... Polymer Substances and Polymer Adjuvants for Food Treatment § 173.55 Polyvinylpyrrolidone. The food... the polyvinylpyrrolidone used in beer is that having an average molecular weight of 360,000 and...

  8. Compatible Blends of Zein and Polyvinylpyrrolidone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Blends of zein and polyvinylpyrrolidone (PVP) were compared based on their tensile properties, thermal properties and morphology. Zein was blended with polyvinylpyrrolidone of varying molecular weights (10,000, 55,000 and 1,300,000 MW) and films were cast from ethanol solutions. Films cast using t...

  9. A long term comparison between Denacol EX-313-treated bovine jugular vein graft and ultrafine polyester fiber graft for reconstruction of tight ventricular outflow tract in dogs.

    PubMed

    Matsumoto, Hideki; Sugiyama, Shino; Shibazaki, Akira; Tanaka, Ryou; Takashima, Kazuaki; Noishiki, Yasuharu; Yamane, Yoshihisa

    2003-03-01

    A Denacol EX-313 (Denacol)-treated bovine venous graft and an ultrafine polyester fiber (UFPF) graft were transplanted as patch graft into the right ventricular outflow tract under extracorporeal circulation in six dogs each experimentally. Hemodynamics in right heart and histological findings around the graft were compared between both groups over a period of one year after grafting. Pressure measurements and angiocardiography were performed through a cardiac catheter. Right ventricular pressure, pulmonary artery pessure, and right ventricle to pulmonary artery gradient were within normal limits in both groups at 1, 2, 3, 4, 6, and 12 months or more after grafting. No difference were seen between the values for the Denacol and the UFPF group. Histologically, the medial surface at the site of grafting was covered with vascular endothelial cells at one month after grafting in both groups. The density of the vascular endothelial cells increased with time after grafting, showing no clear difference between the two groups. Subendothelial layers comprised of collagen fibers, elastic fibers, and inflammatory cells decreased with time in both groups, but there was less cell infiltration in the Denacol group than in the UFPF group at all time points after grafting. In addition, the central cut thickness value of the graft tended to be thinner in the Denacol group than in the UFPF group at all observation time points after grafting. In the Denacol group, very slight metaplasia of cartilage was noted in a portion of the graft margin at six months or more after grafting, but no other abnormalities were observed. These results suggest that the Denacol-treated bovine venous graft has better grafting characteristics than the UFPF graft with easier intra-operative handlings and less tissue reactions after grafting. PMID:12679567

  10. Polyvinylpyrrolidone dewaxing aid for bright stocks

    SciTech Connect

    Achia, B.U.; Shaw, D.H.

    1980-05-20

    Polyvinylpyrrolidone having a number average molecular weight ranging from about 150,000 to 400,000 has been found to be an effective dewaxing aid for bright stock in ketone dewaxing processes. Using as little as 100 ppm based on the waxy oil can result in almost a 50% increase in the filter rate of the dewaxed oils from the wax.

  11. Antimicrobial electrospun silver-, copper- and zinc-doped polyvinylpyrrolidone nanofibers.

    PubMed

    Quirós, Jennifer; Borges, João P; Boltes, Karina; Rodea-Palomares, Ismael; Rosal, Roberto

    2015-12-15

    The use of electrospun polyvinylpyrrolidone (PVP) nanofibers containing silver, copper, and zinc nanoparticles was studied to prepare antimicrobial mats using silver and copper nitrates and zinc acetate as precursors. Silver became reduced during electrospinning and formed nanoparticles of several tens of nanometers. Silver nanoparticles and the insoluble forms of copper and zinc were dispersed using low molecular weight PVP as capping agent. High molecular weight PVP formed uniform fibers with a narrow distribution of diameters around 500 nm. The fibers were converted into an insoluble network using ultraviolet irradiation crosslinking. The efficiency of metal-loaded mats against the bacteria Escherichia coli and Staphylococcus aureus was tested for different metal loadings by measuring the inhibition of colony forming units and the staining with fluorescent probes for metabolic viability and compromised membranes. The assays included the culture in contact with mats and the direct staining of surface attached microorganisms. The results indicated a strong inhibition for silver-loaded fibers and the absence of significant amounts of viable but non-culturable microorganisms. Copper and zinc-loaded mats also decreased the metabolic activity and cell viability, although in a lesser extent. Metal-loaded fibers allowed the slow release of the soluble forms of the three metals. PMID:26142159

  12. Preparation of alumina rods by electrospinning aluminum sec-butoxide/polyvinylpyrrolidone blended solutions.

    PubMed

    Choi, Jinho; Yoon, Yongho; Jung, Jihoon

    2013-09-01

    Aluminum sec-butoxide/polyvinylpyrrolidone (ASB/PVP) solutions, prepared by sol-gel processing of a mixture of ASB and PVP, were electrospun to form ASB/PVP organic-inorganic hybrid fibers. The diameter of alumina nanofibers was in the range of 200 nm to 500 nm. Since the fibers cracked after calcinations at 1100 degrees C, they were cured at 300 degrees C, 400 degrees C and 500 degrees C for 24 h each. The calcination of these composite fibers at temperatures above 1000 degrees C resulted in pure rod-shaped a-alumina. It was analyzed by SEM, TG-DTA, FTIR, and XRD. PMID:24205637

  13. Subwavelength structure for sound absorption from graphene oxide-doped polyvinylpyrrolidone nanofibers

    NASA Astrophysics Data System (ADS)

    Qamoshi, Khadijeh; Rasuli, Reza

    2016-09-01

    We study the sound absorption of the reinforced polyvinylpyrrolidone nanofibers with graphene oxide. It is shown that reinforced nanofibers can acquire impedance-matched surface to airborne sound at special frequencies. To obtain such surface, nanofibers were spun with polyvinylpyrrolidone polymer that was doped by graphene oxide with concentrations of 0, 6 and 12 wt%. It was found that fibers without graphene oxide were spun continuously and randomly, whereas by doping with graphene oxide, the mode of fibers is changed and some nodes form on the fibers coating. The sound absorption coefficient was measured by an impedance tube based on 105341-1 ISO standard. Measurements in the frequency range from 700 to 1600 Hz show that use of graphene oxide as a reinforcing phase increases sound absorption coefficient of the samples at a frequency ~1500 Hz up to ~40 %. Angular eigenfrequency and dissipation coefficient of the samples were obtained by impedance measurement for the prepared samples. Results show that doping the polymer with graphene oxide causes an increase in the angular eigenfrequency and the dissipation coefficient.

  14. Component dynamics in polyvinylpyrrolidone concentrated aqueous solutions.

    PubMed

    Busselez, Rémi; Arbe, Arantxa; Cerveny, Silvina; Capponi, Sara; Colmenero, Juan; Frick, Bernhard

    2012-08-28

    (2)H-nuclear magnetic resonance (NMR) and neutron scattering (NS) on isotopically labelled samples have been combined to investigate the structure and dynamics of polyvinylpyrrolidone (PVP) aqueous solutions (4 water molecules/monomeric unit). Neutron diffraction evidences the nanosegregation of polymer main-chains and water molecules leading to the presence of water clusters. NMR reveals the same characteristic times and spectral shape as those of the slower process observed by broadband dielectric spectroscopy in this system [S. Cerveny et al., J. Chem. Phys. 128, 044901 (2008)]. The temperature dependence of such relaxation time crosses over from a cooperative-like behavior at high temperatures to an Arrhenius behavior at lower temperatures. Below the crossover, NMR features the spectral shape as due to a symmetric distribution of relaxation times and the underlying motions as isotropic. NS results on the structural relaxation of both components-isolated via H/D labeling-show (i) anomalously stretched and non-Gaussian functional forms of the intermediate scattering functions and (ii) a strong dynamic asymmetry between the components that increases with decreasing temperature. Strong heterogeneities associated to the nanosegregated structure and the dynamic asymmetry are invoked to explain the observed anomalies. On the other hand, at short times the atomic displacements are strongly coupled for PVP and water, presumably due to H-bond formation and densification of the sample upon hydration. PMID:22938260

  15. Ultrafine cementitious grout

    SciTech Connect

    Ahrens, Ernst H.

    1998-01-01

    An ultrafine cementitious grout having a particle size 90% of which are less than 6 .mu.m in diameter and an average size of about 2.5 .mu.m or less, and preferably 90% of which are less than 5 .mu.m in diameter and an average size of about 2 .mu.m or less containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 40 wt. % to about 50 wt. % Portland cement; from about 50 wt. % to about 60 wt. % pumice containing at least 60% amorphous silicon dioxide; and from 0.1 wt. % to about 1.5 wt. % superplasticizer. The grout is mixed with water in the W/CM ratio of about 0.4-0.6/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 .mu.m in width.

  16. Ultrafine cementitious grout

    SciTech Connect

    Ahrens, Ernst H.

    1999-01-01

    An ultrafine cementitious grout in three particle grades containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 30 wt. % to about 70 wt. % Portland cement; from about 30 wt. % to about 70 wt. % pumice containing at least 70% amorphous silicon dioxide; and from 1.2 wt. % to about 5.0 wt. % superplasticizer. The superplasticizer is dispersed in the mixing water prior to the addition of dry grout and the W/CM ratio is about 0.4 to 1/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 .mu.m in width.

  17. Ultrafine cementitious grout

    SciTech Connect

    Ahrens, E.H.

    1999-10-19

    An ultrafine cementitious grout in three particle grades containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 30 wt. % to about 70 wt. % Portland cement; from about 30 wt. % to about 70 wt. % pumice containing at least 70% amorphous silicon dioxide; and from 1.2 wt. % to about 5.0 wt. % superplasticizer. The superplasticizer is dispersed in the mixing water prior to the addition of dry grout and the W/CM ratio is about 0.4 to 1/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 {mu}m in width.

  18. Fabrication of Polyvinylpyrrolidone Micro-/Nanostructures Utilizing Microcontact Printing

    ERIC Educational Resources Information Center

    Sanders, Wesley C.

    2015-01-01

    This paper describes a laboratory exercise that provides students enrolled in introductory nanotechnology courses with an opportunity to synthesize polymer structures with micro- and nanoscale dimensions. Polyvinylpyrrolidone (PVP) films deposited on corrugated PDMS stamps using student-built spin coaters were transferred to clean, dry substrates…

  19. Fiber

    MedlinePlus

    ... it can help with weight control. Fiber aids digestion and helps prevent constipation . It is sometimes used ... fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  20. Ultrafine cementitious grout

    DOEpatents

    Ahrens, E.H.

    1998-07-07

    An ultrafine cementitious grout is described having a particle size 90% of which are less than 6 {micro}m in diameter and an average size of about 2.5 {micro}m or less, and preferably 90% of which are less than 5 {micro}m in diameter and an average size of about 2 {micro}m or less containing Portland cement, pumice as a pozzolanic material and superplasticizer in the amounts of about 40 wt. % to about 50 wt. % Portland cement; from about 50 wt. % to about 60 wt. % pumice containing at least 60% amorphous silicon dioxide; and from 0.1 wt. % to about 1.5 wt. % superplasticizer. The grout is mixed with water in the W/CM ratio of about 0.4--0.6/1. The grout has very high strength and very low permeability with good workability. The ultrafine particle sizes allow for sealing of microfractures below 10 {micro}m in width. 4 figs.

  1. Regulation of the reaction of N-polyvinylpyrrolidone with iodine

    SciTech Connect

    Trubitsyna, S.N.

    1985-09-01

    The route chosen for modification of the sorption capacity of N -polyvinylpyrrolidone (PVP) was stabilization of its polymer skeleton by the action of intermolecular hydrogen bonds. The secondary supermolecular formations were regulated by introduction into aqueous solution polyvinylpyrrolidone at room temperature of substances containing active groups tending to form intermolecular H bonds with electron donors-oxygen atoms of carbonyl groups in PVP. Figures show IR absorption spectra of aqueous solutions of PVP, and dependence of the conductivity of aqueous solutions. It was concluded that preliminary addition both of monomeric and polymeric compounds, causing fromation of H bonds in the system, to PVP solutions causes significant changes in the structural organization of the PVP macromolecular chains, as the result of which the polymer acquires high sorption capacity for iodine.

  2. Interdiffusion at the interface between poly(vinylpyrrolidone) and epoxy

    SciTech Connect

    Oyama, H.T.; Wightman, J.P.; Lesko, J.J.; Reifsnider, K.L.

    1996-12-31

    The study of polymer-polymer interfaces is recently attracting great interest. So far, most studies have focused on the interface between thermoplastic polymers, even though the interface between thermoplastic and thermoset polymers is also very important in numerous areas such as adhesion and composites. In the present study, bilayer films of thermoplastic poly(vinylpyrrolidone) and a thermoset epoxy were prepared and their compositional profiles at the interface were examined by electron microprobe analysis.

  3. Ultrafine particles in cities.

    PubMed

    Kumar, Prashant; Morawska, Lidia; Birmili, Wolfram; Paasonen, Pauli; Hu, Min; Kulmala, Markku; Harrison, Roy M; Norford, Leslie; Britter, Rex

    2014-05-01

    Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts. PMID:24503484

  4. Fabrication of mucoadhesive chitosan coated polyvinylpyrrolidone/cyclodextrin/clotrimazole sandwich patches for oral candidiasis.

    PubMed

    Tonglairoum, Prasopchai; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Panomsuk, Suwanee; Kaomongkolgit, Ruchadaporn; Opanasopit, Praneet

    2015-11-01

    This study aims to fabricate clotrimazole (CZ)-composite sandwich nanofibers using electrospinning. The CZ-loaded polyvinylpyrrolidone (PVP)/hydroxypropyl-β-cyclodextrin (HPβCD) fiber was coated with chitosan-cysteine (CS-SH)/polyvinyl alcohol (PVA) to increase the mucoadhesive properties and to achieve a sustained release of the drug from the nanofibers. The nanofibers were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and X-ray diffractometry (XRD). The nanofibers mechanical and mucoadhesive properties, drug release, antifungal activity and cytotoxicity were also assessed. The fibers were in the nanoscale with good mucoadhesive properties. The XRPD revealed a molecular dispersion of amorphous CZ in the nanofibers. The initial fast release of CZ from the nanofibers was achieved. Moreover, the sandwich nanofibers coated for longer times resulted in slower release rates compared with the shorter coating times. The CZ-loaded nanofibers killed the Candida significantly faster than the commercial CZ lozenges at 5, 15 and 30 min and were safe for a 2-h incubation. Therefore, these nanofibers may be promising candidates for the treatment of oral candidiasis. PMID:26256338

  5. Anomalous diffusion of erythrocytes in the presence of polyvinylpyrrolidone.

    PubMed Central

    Fritz, O G

    1984-01-01

    The diffusion coefficient of erythrocytes was measured using quasi-elastic light-scattering (QELS) techniques. The cells were suspended in phosphate-buffered saline solutions with and without a macromolecule, polyvinylpyrrolidone (PVP[360]). In the presence of the PVP(360) an anomalously high diffusion coefficient was measured for metabolizing cells with a normal transmembrane potential. The results are in agreement with experiments on rouleau formation by red blood cells and are supportive of the hypothesis of a long-range coherent interaction between metabolically active biological cells. Images FIGURE 8 FIGURE 9 FIGURE 10 PMID:6478035

  6. Fiber

    MedlinePlus

    ... broccoli, spinach, and artichokes legumes (split peas, soy, lentils, etc.) almonds Look for the fiber content of ... salsa, taco sauce, and cheese for dinner. Add lentils or whole-grain barley to your favorite soups. ...

  7. Fiber

    MedlinePlus

    ... short period of time can cause intestinal gas ( flatulence ), bloating , and abdominal cramps . This problem often goes ... 213. National Research Council. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and ...

  8. Ileocolonic ulcer treated by endoscopic application of collagen-polyvinylpyrrolidone

    PubMed Central

    de Hoyos Garza, Andrés; Aguilar, Edgar A Esparza; Checa Richards, Griselda

    2007-01-01

    Ulceration is a complication that may occur after an ileocolonic anastomosis. Most of the etiologies remain speculative. The case of a 33-year-old woman with eosinophilic colitis is reported, in whom a colectomy with an ileocolonic anastomosis was performed. After four months, the patient presented with a stenosis in the ileocolonic anastomosis, necessitating surgical restoration. Four weeks later, the patient presented with rectal bleeding, and a colonoscopy showed an ulcer in the anastomosis. Collagen-polyvinylpyrrolidone was applied into and on the surface of the ulcer, and five days later the procedure was repeated. Follow-up endoscopies at seven days and three months showed complete healing of the ulcer and the patient remained without bleeding throughout a further four weeks of follow-up tests. It was concluded that this biological product could be an excellent treatment for these lesions. PMID:17703251

  9. Poly(vinylpyrrolidone) for bioconjugation and surface ligand immobilization.

    PubMed

    Zelikin, Alexander N; Such, Georgina K; Postma, Almar; Caruso, Frank

    2007-09-01

    Poly(vinylpyrrolidone) (PVP), a nonionic and nontoxic polymer with antifouling properties, has been synthesized via RAFT polymerization to obtain thiol-terminated PVP. We demonstrate that when the polymer is adsorbed onto the surface of colloidal silica particles, the terminal thiol groups of PVP remain accessible for chemical modification and lend themselves to the immobilization of ligands. We show that ligand attachment onto the surface via conjugation to PVP is reversible, as the polymer can be desorbed from the surface for conjugate and surface recovery. We present the conjugation of a model peptide and an oligonucleotide to PVP via the polymer terminal thiol and demonstrate that conjugates remain functional in molecular recognition assay. The developed technique offers a novel method to functionalize low-fouling surfaces for a variety of biomedical applications and presents opportunities to use PVP as a macromolecular drug carrier. PMID:17715962

  10. Removal of polyvinylpyrrolidone from wastewater using different methods.

    PubMed

    Julinová, Markéta; Kupec, Jan; Houser, Josef; Slavík, Roman; Marusincová, Hana; Cervenáková, Lenka; Klívar, Stanislav

    2012-12-01

    Polyvinylpyrrolidone (PVP) is a frequently used polymer in the pharmaceutical and foodstuff industries. Because it is not subject to metabolic changes and is virtually nondegradable, trace concentrations of PVP are often found in community wastewaters. The literature finds that the partial removal of PVP in wastewater treatment plants probably occurs through sorption. The primary objective of this study was to find an effective method to remove PVP from wastewaters. In this regard, the literature indicates the theoretical potential to use specific enzymes (e.g., gamma-lactamases, amidases) to gradually degrade PVP molecules. Polyvinylpyrrolidone biodegradability tests were conducted using suitable heterogeneous cultures (activated sludge) collected from a conventional wastewater treatment plant, treatment plants connected to a pharmaceutical factory, and using select enzymes. Aerobic biodegradation of PVP in a conventional wastewater environment was ineffective, even after adaptation of activated sludge using the nearly identical monomer 1-methyl-2-pyrrolidone. Another potential method for PVP removal involves pretreating the polymer prior to biological degradation. Based on the results (approximately 10 to 15% biodegradation), pretreatment was partially effective, realistically, it could only be applied with difficulty at wastewater treatment plants. Sorption of PVP to an active carbon sorbent (Chezacarb S), which corresponded to the Langmuir isotherm, and sorption to activated sludge, which corresponded to the Freundlich isotherm, were also evaluated. From these sorption tests, it can be concluded that the considerable adsorption of PVP to activated sludge occurred primarily at low PVP concentrations. Based on the test results, the authors recommend the following methods for PVP removal from wastewater: (1) sorption; (2) application of specific microorganisms; and (3) alkaline hydrolysis, which is the least suitable of the three for use in wastewater treatment

  11. Polyvinylpyrrolidone microneedles enable delivery of intact proteins for diagnostic and therapeutic applications

    PubMed Central

    Sun, Wenchao; Araci, Zeynep; Inayathullah, Mohammed; Manickam, Sathish; Zhang, Xuexiang; Bruce, Marc A.; Marinkovich, M. Peter; Lane, Alfred T.; Milla, Carlos; Rajadas, Jayakumar; Butte, Manish J.

    2013-01-01

    We present a method of fabricating microneedles from polyvinylpyrrolidone (PVP) that enables delivery of intact proteins (or peptides) to the dermal layers of the skin. PVP is known to self-assemble into branched hollow fibers in aqueous and alcoholic solutions; we utilized this property to develop dissolvable patches of microneedles. Proteins were dissolved in concentrated PVP solution in both alcohol and water, poured into polydimethylsiloxane templates shaped as microneedles and, upon evaporation of solvent, formed into concentric, fibrous, layered structures. This approach of making PVP microneedles overcomes problems in dosage, uniform delivery and stability of protein formulation as compared to protein-coated metallic microneedles or photopolymerized PVP microneedles. Here we characterize the PVP microneedles and measure the delivery of proteins into skin. We show that our method of fabrication preserves the protein conformation. These microneedles can serve as a broadly useful platform for delivering protein antigens and therapeutic proteins to the skin, for example for allergen skin testing or immunotherapy. PMID:23648574

  12. Surgical smoke and ultrafine particles

    PubMed Central

    Brüske-Hohlfeld, Irene; Preissler, Gerhard; Jauch, Karl-Walter; Pitz, Mike; Nowak, Dennis; Peters, Annette; Wichmann, H-Erich

    2008-01-01

    Background Electrocautery, laser tissue ablation, and ultrasonic scalpel tissue dissection all generate a 'surgical smoke' containing ultrafine (<100 nm) and accumulation mode particles (< 1 μm). Epidemiological and toxicological studies have shown that exposure to particulate air pollution is associated with adverse cardiovascular and respiratory health effects. Methods To measure the amount of generated particulates in 'surgical smoke' during different surgical procedures and to quantify the particle number concentration for operation room personnel a condensation particle counter (CPC, model 3007, TSI Inc.) was applied. Results Electro-cauterization and argon plasma tissue coagulation induced the production of very high number concentration (> 100000 cm-3) of particles in the diameter range of 10 nm to 1 μm. The peak concentration was confined to the immediate local surrounding of the production side. In the presence of a very efficient air conditioning system the increment and decrement of ultrafine particle occurrence was a matter of seconds, with accumulation of lower particle number concentrations in the operation room for only a few minutes. Conclusion Our investigation showed a short term very high exposure to ultrafine particles for surgeons and close assisting operating personnel – alternating with longer periods of low exposure. PMID:19055750

  13. Polyvinylpyrrolidone/Multiwall Carbon Nanotube Composite Based 36 deg. YX LiTaO{sub 3} Surface Acoustic Wave For Hydrogen Gas Sensing Applications

    SciTech Connect

    Chee, Pei Song; Arsat, Rashidah; He Xiuli; Arsat, Mahyuddin; Wlodarski, Wojtek; Kalantar-zadeh, Kourosh

    2011-05-25

    Poly-vinyl-pyrrolidone (PVP)/Multiwall Carbon Nanotubes (MWNTs) based Surface Acoustic Wave (SAW) sensors are fabricated and characterized, and their performances towards hydrogen gas are investigated. The PVP/MWNTs fibers composite are prepared by electrospinning of the composite aqueous solution deposited directly onto the active area of SAW transducers. Via scanning electron microscopy (SEM), the morphology of the deposited nanostructure material is observed. From the dynamic response, frequency shifts of 530 Hz (1%H{sub 2}) and 11.322 kHz (0.25%H{sub 2}) are recorded for the sensors contain of 1.525 g and 1.025 g PVP concentrations, respectively.

  14. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    SciTech Connect

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-25

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels’ network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  15. Properties of Polyvinylpyrrolidone in a Deep Eutectic Solvent.

    PubMed

    Sapir, Liel; Stanley, Christopher B; Harries, Daniel

    2016-05-19

    Deep eutectic solvents (DES) are mixtures of two or more components with high melting temperatures, which form a liquid at room temperature. These DES hold great promise as green solvents for chemical processes, as they are inexpensive and environmentally friendly. Specifically, they present a unique solvating environment to polymers that is different from water. Here, we use small angle neutron scattering to study the polymer properties of the common, water-soluble, polyvinylpyrrolidone (PVP) in the prominent DES formed by a 1:2 molar mixture of choline chloride and urea. We find that the polymer adopts a slightly different structure in DES than in water, so that at higher concentrations the polymer favors a more expanded conformation compared to the same concentration in water. Yet, the osmotic pressure of PVP solutions in DES is very similar to that in water, indicating that both solvents are of comparable quality and that the DES components interact favorably with PVP. The osmotic pressure measurements within this novel class of promising solvents should be of value toward future technological applications as well as for osmotic stress experiments in nonaqueous environments. PMID:26963367

  16. Properties of radiation-synthesized polyvinylpyrrolidone/chitosan hydrogel blends

    NASA Astrophysics Data System (ADS)

    Mahmud, Maznah; Daik, Rusli; Adam, Zainah

    2015-09-01

    Poly(vinylpyrrolidone) (PVP)-crosslinked chitosan hydrogels were prepared by gamma radiation at various doses; 1, 3 5, 7, 10, 15, 20, 25 and 30kGy. Gamma radiation was used as a crosslinking tool which requires no chemical initiator, no heating process and need no purification step on the end products obtained. The hydrogel formulations were composed of 6% chitosan with average molecular weight (Mw) = 48 800 g/mol and 14% PVP with Mw = 10 000 g/mol in 2% lactic acid. Physical properties of hydrogels such as gel fraction and swelling property at pH 5.5 and pH 7.0 as well as syneresis activity were determined. It was found that different radiation dose induces different effect on hydrogels' network formed. Morphological study of hydrogels has been carried out by scanning electron microscope (SEM). From these preliminary evaluations, it can be concluded that gamma radiation is an effective tool for network development of hydrogels and it also induces enhancement on characteristics of hydrogels synthesized.

  17. Interaction between water and poly(vinylpyrrolidone) containing polyethylene glycol.

    PubMed

    Hamaura, T; Newton, J M

    1999-11-01

    Information on the interaction between water and polymers is indispensable for manufacturing solid dispersion of a drug by hot-melt extrusion because this interaction affects various properties of the water-polymer mixtures, such as their viscoelastic properties. In this study, poly(vinylpyrrolidone) K30 (PVP) containing 0%, 10%, and 20% poly(ethylene glycol) 400 (PEG) was used as model amorphous polymers. The interaction of water with these polymers was assessed by the evaluation of the glass transition temperature (Tg), the point on the isotherm corresponding to the weight of sorbed water required to form a complete monolayer on the solid surface (apparent Wm), and the maximal amount of nonfreezing water, which were measured by differential scanning calorimetry and water sorption isotherms. In all of the systems with a water content below a certain water fraction (0.1 for PVP, 0.12 for PVP-PEG 10%, and 0.16 for PVP-PEG 20%), the Tg values were successfully predicted using theoretical equations, whereas the experimental Tg values were higher than predicted for those with a water content above these water fraction levels. In addition, these values of water fraction are similar to the apparent W(m) values determined using the Guggenheim-Anderson-DeBoer (GAB) equation (0.110, 0.117, and 0.147 weight fraction of water for PVP, PVP-PEG 10%, and PVP-PEG 20%, respectively). Nonfreezing water is detected above 0.47, 0.49, and 0.51 weight fraction of water for PVP, PVP-PEG 10%, and PVP-PEG 20%, respectively. Miscibility between water and PVP or PVP-PEG seems to change according to the water content in the system. All parameters increase with the concentration of PEG in the sample. This may be explained by the fact that PEG has a larger number of polymer repeating units, which may therefore interact with water more than PVP. PMID:10564074

  18. Anti-tack action of polyvinylpyrrolidone on hydroxypropylmethylcellulose solution.

    PubMed

    Chan, Lai Wah; Wong, Tin Wui; Chua, Pih Chng; York, Peter; Heng, Paul Wan Sia

    2003-02-01

    The anti-tack action of polyvinylpyrrolidone (PVP) on hydroxypropylmethylcellulose (HPMC) solution was elucidated using a probe test method. The influence of PVP of varying molecular weights at various PVP concentrations and solution temperatures on the tackiness of HPMC solution was studied. The viscosity, surface tension, cloud point and solution spectroscopy of HPMC solutions and glass transition temperature of HPMC films, with and without PVP, were investigated. The tackiness of HPMC solutions in response to the addition of PVP, at different concentrations of HPMC and using HPMC with varying contents of hydroxypropyl/methoxyl substitution, was also evaluated. PVP is a commonly used binder and adhesive. However, it reduced the tack of the HPMC solution when used at low concentrations, without affecting the state of hydration of HPMC. Lower molecular weight PVP was more effective as an anti-tack agent owing to suitable hydrodynamic size to intersperse among the HPMC chains. The degree of reduction in tack values was more pronounced for HPMC that showed a greater extent of interaction between polymer chains such as when high concentration of HPMC or low solution temperature was employed. This indicated that the tack reduction property of PVP relied on its ability to interact with the HPMC chains. The profile of reduction in tack values was affected by the contents of HPMC substitution and was a result of net reduction in the extent of hydrogen bonding between HPMC chains. It was significantly correlated to the changes of viscosity and surface tension of the HPMC solutions but not to the glass transition temperatures of the polymers prepared as solid films. The results suggested that the anti-tack action of PVP was attributed to its ability to interact with HPMC chains in the aqueous medium and consequently to reduce the extent of HPMC-HPMC bonding. PMID:12576641

  19. Effect of reductant and PVP on morphology and magnetic property of ultrafine Ni powders prepared via hydrothermal route

    SciTech Connect

    Zhang, Jun Wang, Xiucai; Li, Lili; Li, Chengxuan; Peng, Shuge

    2013-10-15

    Graphical abstract: The ultrafine Ni powders with the shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using different reductants. Their saturation magnetization, remanent magnetization and coercivity sequentially increase, and the coercivity of hexagonal sheet-like Ni powders increases by 25% compared with the Ni bulk counterpart. - Highlights: • The ultrafine Ni powders with various shapes of sphere, fish-bone, hexagonal sheet, etc. • Facile and one-step hydrothermal reduction using three reductants and PVP additive was developed. • Magnetic properties of the ultrafine Ni powders with different shapes were measured. • Compared with bulk Ni material, coercivity of hexagonal sheet Ni increases by 25%. • The formation mechanism of the shapes was suggested. - Abstract: The ultrafine nickel particles with different shapes including sphere, pearl-string, leaf, fish-bone, hexagonal sheet and silknet were prepared through one-step hydrothermal reduction using hydrazine hydrate, sodium hypophosphite and ethylene glycol as reductants, polyvinylpyrrolidone as structure-directing agent. It has been verified with the characterization of X-ray powder diffraction and transmission/scanning electronic microscopy that as-prepared products belong to face-centered cubic structure of nickel microcrystals with high purity and fine dispersity. The magnetic hysteresis loops measured at room temperature reveal that the values of saturation magnetization, remanent magnetization and coercivity rise sequentially from silknet, sphere to hexagonal sheet. In comparison with nickel bulk counterpart, the coercivity of the hexagonal sheet nickel powders increases by 25%.

  20. Ultrafine-grained titanium for medical implants

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Valiev, Ruslan Z.; Stolyarov, Vladimir V.; Latysh, Vladimir V.; Raab, Georgy J.

    2002-01-01

    We disclose ultrafine-grained titanium. A coarse-grained titanium billet is subjected to multiple extrusions through a preheated equal channel angular extrusion (ECAE) die, with billet rotation between subsequent extrusions. The resulting billet is cold processed by cold rolling and/or cold extrusion, with optional annealing. The resulting ultrafine-grained titanium has greatly improved mechanical properties and is used to make medical implants.

  1. Method for synthesizing ultrafine powder materials

    DOEpatents

    Buss, Richard J.; Ho, Pauline

    1988-01-01

    A method for synthesizing ultrafine powder materials, for example, ceramic and metal powders, comprises admitting gaseous reactants from which the powder material is to be formed into a vacuum reaction chamber maintained at a pressure less than atmospheric and at a temperature less than about 400.degree. K. (127.degree.C.). The gaseous reactants are directed through a glow discharge provided in the vacuum reaction chamber to form the ultrafine powder material.

  2. Water-stable three-dimensional ultrafine fibrous scaffolds from keratin for cartilage tissue engineering.

    PubMed

    Xu, Helan; Cai, Shaobo; Xu, Lan; Yang, Yiqi

    2014-07-22

    Intrinsically water-stable scaffolds composed of ultrafine keratin fibers oriented randomly and evenly in three dimensions were electrospun for cartilage tissue engineering. Keratin has been recognized as a biomaterial that could substantially support the growth and development of multiple cell lines. Besides, three-dimensional (3D) ultrafine fibrous structures were preferred in tissue engineering due to their structural similarity to native extracellular matrices in soft tissues. Recently, we have developed a nontraditional approach to developing 3D fibrous scaffolds from alcohol-soluble corn protein, zein, and verified their structural advantages in tissue engineering. However, keratin with highly cross-linked molecular structures could not be readily dissolved in common solvents for fiber spinning, which required the remarkable drawability of solution. So far, 3D fibrous scaffolds from pure keratin for biomedical applications have not been reported. In this research, the highly cross-linked keratin from chicken feathers was de-cross-linked and disentangled into linear and aligned molecules with preserved molecular weights, forming highly stretchable spinning dope. The solution was readily electrospun into scaffolds with ultrafine keratin fibers oriented randomly in three dimensions. Due to the highly cross-linked molecular structures, keratin scaffolds showed intrinsic water stability. Adipose-derived mesenchymal stem cells could penetrate much deeper, proliferate, and chondrogenically differentiate remarkably better on the 3D keratin scaffolds than on 2D PLA fibrous scaffolds, 3D soy protein fibrous scaffolds, or 3D commercial nonfibrous scaffolds. In summary, the electrospun 3D ultrafine fibrous scaffolds from keratin could be promising candidates for cartilage tissue engineering. PMID:25010870

  3. Spectral properties of zinc sulfide sols stabilized by high-molecular polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Evstrop'ev, S. K.; Gatchin, Yu. A.; Evstrop'ev, K. S.; Dukel'skii, K. V.; Kislyakov, I. M.

    2015-12-01

    Spectral properties of zinc sulfide sols stabilized by high-molecular polyvinylpyrrolidone have been studied. It is shown that the absorption spectra of colloidal solutions in the UV spectral range are determined by the quantum-confinement effect, exhibiting a dependence of the absorption edge on the size of zinc sulfide nanocrystals.

  4. The formation of ZnO-based coatings from solutions containing high-molecular polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Evstrop'ev, S. K.; Soshnikov, I. P.; Khrebtov, A. I.

    2016-05-01

    A method for deposition of transparent nanosize ZnO-based coatings on the glass surface from solutions containing high-molecular polyvinylpyrrolidone is described. The method can be used to form transparent homogeneous coatings based on ZnO with an increased energy gap width. It does not require any intricate technological equipment.

  5. X-ray diffraction investigation of ultrafine boron nitride powders

    SciTech Connect

    Gurov, S.V.; Chukalin, V.I.; Rezchikova, T.V.; Torbov, V.J.; Troitskii, V.N.

    1986-01-01

    This paper presents an x-ray diffraction analysis of ultrafine boron nitride powders of different mean particle sizes. Diffraction spectra of the ultrafine boron nitride powders were obtained using a DRON-1 apparatus. The experimental facts are indicative of a turbostratic character of deformation of the hexagonal lattice of ultrafinely divided boron nitride.

  6. Preparation and Thermal Stability of Ultrafine Nickel Powders Containing hcp-Ni Nanocrystallites Using Liquid-Phase Reduction Method

    NASA Astrophysics Data System (ADS)

    Xia, Zhimei; Jin, Shengming; Liu, Kun

    2016-08-01

    Ultrafine nickel powders containing hexagonal close-packed nickel (hcp-Ni) nanocrystallites were prepared using liquid-phase reduction with NiC2O4, NaOH, polyvinylpyrrolidone (PVP), and ethylene glycol (EG). The nickel powders were characterized by XRD and SEM. TG analysis was used to determine the thermal stability of ultrafine nickel powders. The results showed that nickel powders with 45.1 pct of hcp-Ni nanocrystallites were synthesized under the following conditions: a reflux time of 3 hours, an NiC2O4-to-EG molar ratio of 0.01, 5 g/L PVP, and 85 g/L NaOH. SEM results illustrated that spherical particles of size 500 nm were obtained. The results of thermal stability showed that the antioxidant property at high temperature was improved with the increase of hcp-Ni content. The oxidation rate of nickel powders with 43.3 pct hcp-Ni was less than 50 pct even if the temperature was up to 873 K (600 °C).

  7. Synthesis of ultrafine powders by microwave heating

    DOEpatents

    Meek, Thomas T.; Sheinberg, Haskell; Blake, Rodger D.

    1988-01-01

    A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has been removed. The resulting material is an ultrafine powder. This method can be used to make Al.sub.2 O.sub.3, NiO+Al.sub.2 O.sub.3 and NiO as well as a number of other materials including GaBa.sub.2 Cu.sub.3 O.sub.x.

  8. Synthesis of ultrafine powders by microwave heating

    DOEpatents

    Meek, T.T.; Sheinberg, H.; Blake, R.D.

    1987-04-24

    A method of synthesizing ultrafine powders using microwaves is described. A water soluble material is dissolved in water and the resulting aqueous solution is exposed to microwaves until the water has dissolved. The resulting material is an ultrafine powder. This method can be used to make Al/sub 2/O/sub 3/, NiO /plus/ Al/sub 2/O/sub 3/ and NiO as well as a number of other materials including GaBa/sub 2/Cu/sub 3/O/sub x/. 1 tab.

  9. Ultrafine particle characteristics in seven industrial plants.

    PubMed

    Elihn, Karine; Berg, Peter

    2009-07-01

    Ultrafine particles are considered as a possible cause of some of the adverse health effects caused by airborne particles. In this study, the particle characteristics were measured in seven Swedish industrial plants, with a special focus on the ultrafine particle fraction. Number concentration, size distribution, surface area concentration, and mass concentration were measured at 10 different job activities, including fettling, laser cutting, welding, smelting, core making, moulding, concreting, grinding, sieving powders, and washing machine goods. A thorough particle characterization is necessary in workplaces since it is not clear yet which choice of ultrafine particle metric is the best to measure in relation to health effects. Job activities were given a different order of rank depending on what particle metric was measured. An especially high number concentration (130 x 10(3) cm(-3)) and percentage of ultrafine particles (96%) were found at fettling of aluminium, whereas the highest surface area concentration (up to 3800 mum(2) cm(-3)) as well as high PM10 (up to 1 mg m(-3)) and PM1 (up to 0.8 mg m(-3)) were found at welding and laser cutting of steel. The smallest geometric mean diameter (22 nm) was found at core making (geometric standard deviation: 1.9). PMID:19447849

  10. Dependence of the solubility of natural flavonoids in water on the concentration of miramistin, polyvinylpyrrolidone, and human serum albumin

    NASA Astrophysics Data System (ADS)

    Lipkovska, N. A.; Barvinchenko, V. N.; Fedyanina, T. V.

    2014-05-01

    In organized media of the cationic surfactant miramistin and the polymers polyvinylpyrrolidone and human serum albumin, the solubility of natural flavonoids quercetin and rutin increased by one or two orders of magnitude. The increase was more significant for hydrophobic quercetin than for hydrophilic rutin. The solubility also depended on the structure and self-organization of molecules in organized media and the site of flavonoids in them. The calculated binding constants increased in the series polyvinylpyrrolidone < miramistin < human serum albumin.

  11. Photoinduced variation of the luminescent properties of PbS nanoparticle suspensions stabilized by polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Bagrov, I. A.; Danilov, V. V.; Evstrop'ev, S. K.; Kiselev, V. M.; Kislyakov, I. M.; Panfutova, A. S.; Khrebtov, A. I.

    2015-01-01

    We have observed a significant increase in the intensity of photoluminescence (PL) from polyvinylpyrrolidone-stabilized suspensions of PbS quantum dots upon irradiation in a broad spectral range and subsequent storage in the dark at room temperature. It is also established that analogous changes are observed in dense polymer coatings deposited on glass substrates from these suspensions. It is suggested that the observed changes in PL intensity are related to the evolution of the clusters of PbS quantum dots.

  12. Positron annihilation lifetime study of polyvinylpyrrolidone for nanoparticle-stabilizing pharmaceuticals.

    PubMed

    Shpotyuk, O; Bujňáková, Z; Baláž, P; Ingram, A; Shpotyuk, Y

    2016-01-01

    Positron annihilation lifetime spectroscopy was applied to characterize free-volume structure of polyvinylpyrrolidone used as nonionic stabilizer in the production of many nanocomposite pharmaceuticals. The polymer samples with an average molecular weight of 40,000 g mol(-1) were pelletized in a single-punch tableting machine under an applied pressure of 0.7 GPa. Strong mixing in channels of positron and positronium trapping were revealed in the polyvinylpyrrolidone pellets. The positron lifetime spectra accumulated under normal measuring statistics were analysed in terms of unconstrained three- and four-term decomposition, the latter being also realized under fixed 0.125 ns lifetime proper to para-positronium self-annihilation in a vacuum. It was shown that average positron lifetime extracted from each decomposition was primary defined by long-lived ortho-positronium component. The positron lifetime spectra treated within unconstrained three-term fitting were in obvious preference, giving third positron lifetime dominated by ortho-positronium pick-off annihilation in a polymer matrix. This fitting procedure was most meaningful, when analysing expected positron trapping sites in polyvinylpyrrolidone-stabilized nanocomposite pharmaceuticals. PMID:26444751

  13. Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis.

    PubMed

    Zhai, Yueming; DuChene, Joseph S; Wang, Yi-Chung; Qiu, Jingjing; Johnston-Peck, Aaron C; You, Bo; Guo, Wenxiao; DiCiaccio, Benedetto; Qian, Kun; Zhao, Evan W; Ooi, Frances; Hu, Dehong; Su, Dong; Stach, Eric A; Zhu, Zihua; Wei, Wei David

    2016-08-01

    After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. Herein, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally different from its widely accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. These insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms. PMID:27376686

  14. Polyvinylpyrrolidone-induced anisotropic growth of gold nanoprisms in plasmon-driven synthesis

    NASA Astrophysics Data System (ADS)

    Zhai, Yueming; Duchene, Joseph S.; Wang, Yi-Chung; Qiu, Jingjing; Johnston-Peck, Aaron C.; You, Bo; Guo, Wenxiao; Diciaccio, Benedetto; Qian, Kun; Zhao, Evan W.; Ooi, Frances; Hu, Dehong; Su, Dong; Stach, Eric A.; Zhu, Zihua; Wei, Wei David

    2016-08-01

    After more than a decade, it is still unknown whether the plasmon-mediated growth of silver nanostructures can be extended to the synthesis of other noble metals, as the molecular mechanisms governing the growth process remain elusive. Herein, we demonstrate the plasmon-driven synthesis of gold nanoprisms and elucidate the details of the photochemical growth mechanism at the single-nanoparticle level. Our investigation reveals that the surfactant polyvinylpyrrolidone preferentially adsorbs along the nanoprism perimeter and serves as a photochemical relay to direct the anisotropic growth of gold nanoprisms. This discovery confers a unique function to polyvinylpyrrolidone that is fundamentally different from its widely accepted role as a crystal-face-blocking ligand. Additionally, we find that nanocrystal twinning exerts a profound influence on the kinetics of this photochemical process by controlling the transport of plasmon-generated hot electrons to polyvinylpyrrolidone. These insights establish a molecular-level description of the underlying mechanisms regulating the plasmon-driven synthesis of gold nanoprisms.

  15. Concentrated ambient ultrafine particle exposure induces cardiac change in young healthy volunteers

    EPA Science Inventory

    Exposure to ambient ultrafine particles has been associated with cardiopulmonary toxicity and mortality. Adverse effects specifically linked to ultrafine particles include loss of sympathovagal balance and altered hemostasis. To characterize the effects of ultrafine particles in ...

  16. Understanding Detonation Corner Turning within Ultra-Fine TATB: Measurements and Modeling

    NASA Astrophysics Data System (ADS)

    Sinibaldi, Jose; Vitello, Peter; May, Chadd

    2013-06-01

    Detonation corner turning within insensitive high explosives has demonstrated difficulties as the insensitivity of the high explosive increases. Experiments tend to report breakout profiles, which show times of arrival of the detonation wave at the surface of the IHE charge. Although, various reactive flow models are able to predict these breakout profiles, none of these models agree perfectly with each other. Models predict major differences in pressure profiles and in the internal detonation wave propagation characteristics. Thus, the objective of this study was to provide detailed accounts of the wave propagation within an ultra-fine TATB charge, through the use embedded fiber-optic diagnostics that allowed measuring the detonation wave propagation within the ultra-fine TATB charges. In addition, these experiments were also instrumented at multiple points with Photonic Doppler Velocimetry to provide dynamic pressure profiles at the hemispherical surface; and orthogonal streak cameras to provide the conventional breakout profiles. Comparisons between experimental data and simulation results using a high resolution reactive flow model for ultra-fine TATB will be presented. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  17. Strength and impact toughness of low-carbon steel with fibrous ultrafine-grained structure

    NASA Astrophysics Data System (ADS)

    Safarov, I. M.; Korznikov, A. V.; Galeev, R. M.; Sergeev, S. N.; Gladkovskii, S. V.; Borodin, E. M.; Pyshmintsev, I. Yu.

    2014-03-01

    The effect of severe warm rolling on the structure and mechanical characteristics of the 12GBA low-carbon steel has been studied. A fibrous ultrafine-grained structure has been formed; the average transverse size of structural elements was 0.5 μm and the length of fibers in the longitudinal section was 20-25 μm. An analysis of this ultrafine-grained structure in transverse and longitudinal sections was carried out using the method of electron backscatter diffraction. It has been shown that the formation of the fibrous structure results in a twofold increase in the strength of the steel in comparison with the original coarse-grained state, with retaining satisfactory ductility. The additional annealing of the steel leads to a slight decrease in its strength characteristics, but results in the complete restoration of its ductile characteristics to the values typical of the coarse-grained state. Impact tests at negative temperatures have shown that, after rolling, the cold-brittleness threshold shifts toward a lower temperature range (from -30 to -60°C) in comparison with the coarse-grained state. It has been found that the formation of the ultrafine-grained state leads to a decrease in the cold-brittleness threshold of the 12GBA steel, as well as to an increase in its impact toughness in the low-temperature range and in the contribution of the crack-propagation work to the total work of fracture of a specimen.

  18. Ultra-fine grinding of coal

    SciTech Connect

    Wang Shoulu; Wang Xinguo; Gao Ying

    1997-12-31

    Clean coal is known by its low ash content. Most coals contain a large amount of ash, some of which are finely distributed in the coal matrix. With the conventional cleaning process, such ash can not be removed efficiently. From existing coal preparation plants, much middling and high-ash slime come out as by-products and are used only as inferior fuel. Beijing Graduate School, China University of Mining and Technology, has developed a process for deep-cleaning of coal. This process includes ultra-fine grinding of coal to liberate the locked ash minerals followed by efficient separation with selective coagulation-flotation. With this process, concentrate can be extracted from inferior coal or ultra-clean coal can be obtained from conventional concentrate. Tumbling and vibrating ball mills are conventional for general grinding. However, for ultra-fine grinding they are inefficient and consume much more power. This paper gives some aspects of an ultra-fine grinding mill developed by Beijing Graduate School. The Ultra-Fine Grinding Mill is a JMI series wet grinding mill, and consists of a static horizontal closed tube with a rotor inside. The rotor assembly includes: a horizontal shaft, two vaned disks being fixed apart at the shaft, and longitudinal bar deflectors fixed across the disks. Sufficient clearance is allowed between the disk and end plates of the tube and between the disk rim and tube wall. This configuration enables free passage of grinding medium and pulp within the mill. While the mill is in operation, four principal movements of grinding medium and pulp are created: inward radially by deflectors, oppositely axial by vanes, tangential by rotation, and vibrating due to vortices behind the deflectors.

  19. [Ultrafine particle emissions from laser printers].

    PubMed

    Grana, Mario; Vicentini, Laura; Pietroiusti, Antonio; Magrini, Andrea

    2015-01-01

    In recent years there has been growing attention to the importance of indoor air quality on which scientist and experts have no doubts since in modern society we tend to spend most of the time in various types of indoor environments (office, private homes, etc.). Laser printers, in particular, release an aerosol into the environment including solid and liquid particles and gaseous compounds. The measurement of all these components is not practically feasible. Therefore, it is necessary to identify a marker which, when measured, shows accurately the frequency, duration and magnitude of the exposure. The measure with an optical particle counter (OPC) and a condensation particle counter (CPC) is an indicator with high sensitivity and representativeness. The major advantage of using these tools is the ability to detect the presence of ultrafine particles and also detect the particles in the liquid phase. The continuous recording of submicron particulate matter emitted during the printing activity allows to measure the exposure of personnel, while the ratio between the peak values and the values without printing activity can be used to classify the printers according to their emissivity. The particulate generated during the processes of printing has size less than 0.3 micron and therefore extends in the size range of nanoparticles (ultrafine particles less than 100 nm). These activities lead to high concentrations of ultrafine particles with a variability related to factors such as type of printer, toner, paper type, frequency of maintenance and air exchange. The concentrations of ultrafine particles in office environments can be reduced by proper choice of the printers, with the use of appropriate filtration techniques and placing the equipment away from workstations. PMID:26749975

  20. Ultrafine polysaccharide nanofibrous membranes for water purification.

    PubMed

    Ma, Hongyang; Burger, Christian; Hsiao, Benjamin S; Chu, Benjamin

    2011-04-11

    Ultrafine polysaccharide nanofibers (i.e., cellulose and chitin) with 5-10 nm diameters were employed as barrier layers in a new class of thin-film nanofibrous composite (TFNC) membranes for water purification. In addition to concentration, the viscosity of the polysaccharide nanofiber coating suspension was also found to be affected by the pH value and ionic strength. When compared with two commercial UF membranes (PAN10 and PAN400), 10-fold higher permeation flux with above 99.5% rejection ratio were achieved by using ultrafine cellulose nanofibers-based TFNC membranes for ultrafiltration of oil/water emulsions. The very high surface-to-volume ratio and negatively charged surface of cellulose nanofibers, which lead to a high virus adsorption capacity as verified by MS2 bacteriophage testing, offer further opportunities in drinking water applications. The low cost of raw cellulose/chitin materials, the environmentally friendly fabrication process, and the impressive high-flux performance indicate that such ultrafine polysaccharide nanofibers-based TFNC membranes can surpass conventional membrane systems in many different water applications. PMID:21341679

  1. Spectral and Luminescence Properties of Sols and Coatings Containing CdS/ZnS QDs and Polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Evstrop'ev, K. S.; Gatchin, Yu. A.; Evstrop'ev, S. K.; Dukel'skii, K. V.; Kislyakov, I. M.; Pegasova, N. A.; Bagrov, I. V.

    2016-03-01

    Spectral and luminescence properties of sols and composition coatings containing cadmium and zinc sulfides and high-molecular polyvinylpyrrolidone have been studied. It is shown that the absorption spectra of colloidal solutions in the UV spectral range are determined by the quantum-confinement effect and exhibit a dependence of the absorption edge on the size of cadmium sulfide nanocrystals. The size of forming particles of metal sulfides has been found to decrease with an increase in the relative content of polyvinylpyrrolidone. It is shown that the order of mixing of the initial components when synthesizing sols also determines the difference in the size of forming particles and their spectral properties.

  2. In vitro antimicrobial activity of solution blow spun poly(lactic acid)/ polyvinylpyrrolidone nanofibers loaded with Copaiba (Copaifera sp.) oil

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this study poly(lactic acid)(PLA) and polyvinylpyrrolidone (PVP) micro and nanofibers mats loaded with copaiba (Copaifera sp.) oil were produced by solution blow spinning (SBS). The copaiba (Copaifera sp.) oil was characterized by gas chromatography (GC). Neat PLA and four PLA/ PVP blends contain...

  3. Li2S cathode modified with polyvinylpyrrolidone and mechanical milling with carbon

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Nara, Hiroki; Yokoshima, Tokihiko; Momma, Toshiyuki; Osaka, Tetsuya

    2015-01-01

    Polyvinylpyrrolidone (PVP) is used with polyethylene oxide (PEO) as a mixed binder for mechanically milled Li2S. PVP demonstrates its advantage in terms of increasing the capacity of Li2S, but boosts the potential barrier at the beginning of the first charge. It is also revealed that PVP retards the charge-transfer kinetics of Li2S. In Li2S-C prepared by mechanical milling, carbon compensates for the electrochemical insulation of the PVP binder and improves the cycle stability. As a result, the Li2S-C-PVP electrode with 60 wt% Li2S content displays a low potential barrier at the onset of charge and a stable capacity of about 460 mAh g-1 at 0.1 C.

  4. Effect of chronic douching with polyvinylpyrrolidone-iodine on iodine absorption and thyroid function

    SciTech Connect

    Safran, M.; Braverman, L.E.

    1982-07-01

    Daily vaginal douching with polyvinylpyrrolidone-iodine in 12 euthyroid volunteers for 14 days resulted in a significant increase in serum total iodine concentration and urine iodine excretion. The increase in serum total iodine was associated with a marked decrease in 24-hour /sup 123/I uptake by the thyroid and a small but significant increase in serum thyrotropin (TSH) concentration. However, values for serum TSH never rose above the normal range. No significant changes in serum thyroxine (T4), free T4 index (FTI), or triiodothyronine concentrations were observed, although serum T4 and FTI did decrease slightly during treatment. The findings suggest that iodine is absorbed across the vaginal mucosa and that the subsequent increase in serum total iodine does induce subtle increases in serum TSH concentration. There was no evidence, however, of overt hypothyroidism in these euthyroid women.

  5. Room temperature optical and magnetic properties of polyvinylpyrrolidone capped ZnO nanoparticles

    SciTech Connect

    Chakrabarti, Mahuya; Chakrabarti, Keka R.; Sanyal, D.; Chakrabarti, A.

    2009-09-15

    Defect induced room temperature ferromagnetic properties of polyvinylpyrrolidone (PVP) capped nanocrystalline ZnO samples have been studied. Crystal phase and the lattice parameter of the synthesized nanocrystalline samples have been determined from X-ray diffraction spectra (XRD) and high-resolution transmission electron micrographs (HR-TEM). Room temperature photoluminescence (PL) spectrum for the bare ZnO sample shows a strong band at {approx} 379 nm and another band at {approx} 525 nm. The PL spectra also revealed that the number of oxygen vacancies in the uncapped sample is more than the PVP capped sample. Both sample exhibit ferromagnetic property at room temperature when annealed at 500 deg. C for 3 h, due to the formation of adequate oxygen vacancy related defects. The saturation magnetization for the annealed PVP capped sample is found to be larger compared to that for the uncapped sample.

  6. CARDIOVASCULAR EFFECTS OF ULTRAFINE CARBON PARTICLES IN HYPERTENSIVE RATS (SHR)

    EPA Science Inventory

    Rationale: Epidemiological evidence suggests that ultrafine particles are associated with adverse cardiovascular effects, specifically in elderly individuals with preexisting cardiovascular disease. The objective of this study was (i) to assess cardiopulmonary responses in adult ...

  7. Ultrafine particle measurement and related EPA research studies

    EPA Science Inventory

    Webinar slides to present information on measuring ultrafine particles at the request of the 2013 MARAMA Monitoring Committee. The talk covers near-road monitoring, instrument intercomparison, and general overview of UFP monitoring technology.

  8. ULTRAFINE PARTICLE DEPOSITION IN HEALTHY SUBJECTS VS. PATIENTS WTH COPD

    EPA Science Inventory

    Individuals affected with chronic obstructive pulmonary disease (COPD) have increased susceptibility to adverse health effects from exposure to particulate air pollution. The dosimetry of ultrafine aerosols (diameter # 0.1 :m) is not well characterized in the healthy or diseas...

  9. HUMAN CLINICAL STUDIES OF CONCENTRATED AMBIENT ULTRAFINE AND FINE PARTICLES

    EPA Science Inventory

    Confirmation of our hypothesis that exposure to ambient ultrafine and fine particles promotes coagulation and alters cardiac function will have important implications for air pollution regulatory efforts, and will provide new approaches for the prevention of cardiovascular hea...

  10. Filtration of ultrafine metallic particles in industry.

    PubMed

    Bémer, D; Morele, Y; Régnier, R

    2015-01-01

    Thermal metal spraying, metal cutting and arc welding processes generate large quantities of ultrafine particles that cause the irreversible clogging of industrial filters. The aim of the study performed was to identify the causes of the clogging of cartridge filters and investigate other paths for cleaning them. This study required the development of a test bench capable of reproducing a thermal spraying process to test the performances of different filtration techniques. This test instrument first, permitted the precise characterization of the aerosol generated by the process and, second, defined the clogging and cleaning conditions for filters. Several parameters were tested: the type of filter, online and off-line cleaning, pre-coating, cleaning by jets of high-speed compressed air via a probe. PMID:25759204

  11. Pulmonary response to inhaled Kevlar aramid synthetic fibers in rats.

    PubMed

    Lee, K P; Kelly, D P; Kennedy, G L

    1983-11-01

    Groups of male rats were exposed to specially prepared ultrafine Kevlar pulp fibers (du Pont's registered trademark for certain aramid fibers) at atmospheric concentrations of either 0.1, 0.5, 3.0, or 18 mg/m3 for 2 weeks. Rats were killed at 0 and 2 weeks and 3 and 6 months postexposure (PE) except the rats exposed to 18 mg/m3, which were killed 0, 4, and 14 days and 1, 3, and 6 months PE. Another group of male rats was exposed to 18 mg/m3 (respirable dust approximately 2.5 mg/m3) of commercial Kevlar fibers for 2 weeks and were killed at 0 and 2 weeks and 3 and 6 months PE. Inhaled ultrafine Kevlar fibers were mostly phagocytized by alveolar macrophages (dust cells) in the alveolar ducts and adjoining alveoli after exposure to either 0.1 or 0.5 micrograms/m3. Most dust cells had disappeared and lungs showed a normal appearance throughout 6 months PE. The pulmonary response almost satisfied the biological criteria for a nuisance dust. Rats exposed to 3 mg/m3 ultrafine Kevlar fibers revealed occasional patchy thickening of alveolar ducts with dust cells and inflammatory cells but with no collagen fibers deposited throughout 6 months PE. After exposure to 18 mg/m3 ultrafine Kevlar, the respiratory bronchioles, alveolar ducts, and adjoining alveoli showed granulomatous lesions with dust cells by 2 weeks PE. The granulomatous lesions converted to patchy fibrotic thickening with dust cells after 1 month PE. The fibrotic lesions were markedly reduced in cellularity, size, and numbers from 3 to 6 months PE but revealed networks of reticulum fibers with slight collagen fiber deposition. PMID:6636189

  12. Room temperature synthesis and optical studies on Ag and Au mixed nanocomposite polyvinylpyrrolidone polymer films

    NASA Astrophysics Data System (ADS)

    Udayabhaskar, R.; Mangalaraja, R. V.; Manikandan, D.; Arjunan, V.; Karthikeyan, B.

    2012-12-01

    Optical properties of silver, gold and bimetallic (Au:Ag) nanocomposite polymer films which are prepared by chemical method have been reported. The experimental data was correlated with the theoretical calculations using Mie theory. We adopt small change in the theoretical calculations of bimetallic/mixed particle nanocomposite and the theory agrees well with the experimental data. Polyvinylpyrrolidone (PVP) was used as reducing and capping agent. Fourier transform infrared spectroscopy (FTIR) study reveals the presence of different functional groups, the possible mechanism that leads to the formation of nanoparticles by using PVP alone as reducing agent. Optical absorption spectra of Ag and Au nanocomposite polymers show a surface plasmon resonance (SPR) band around 430 and 532 nm, respectively. Thermal annealing effect on the prepared samples at 60 °C for different time durations result in shift of SPR band maximum and varies the full width at half maximum (FWHM). Absorption spectra of Au:Ag bimetallic films show bands at 412 and 547 nm confirms the presence of Ag and Au nanoparticles in the composite.

  13. Comparison of the effect of chitosan and polyvinylpyrrolidone on dissolution properties and analgesic effect of naproxen.

    PubMed

    Zerrouk, Naima; Mennini, Natascia; Maestrelli, Francesca; Chemtob, Chantal; Mura, Paola

    2004-01-01

    The solubilizing and absorption enhancer properties towards naproxen of chitosan and polyvinylpyrrolidone (PVP) have been investigated. Solid binary systems prepared at various drug-polymer ratios by mixing, cogrinding or kneading, were characterized by differential scanning calorimetry, X-ray diffractometry, Fourier transform infrared spectroscopy, and scanning electron microscopy, and tested for dissolution behavior. Both carriers improved drug dissolution and their performance depended on the drug-polymer ratio and the system preparation method. Chitosan was more effective than PVP, despite the greater amorphizing power of PVP as revealed by solid state analyses. The 3/7 (w/w) drug-carrier coground systems with chitosan and PVP were the best products enabling, respectively, an improvement of 4.8 and 3.6 times of drug dissolution efficiency. In vivo experiments in mice demonstrated that administration of 45 mg/kg of drug coground with PVP or chitosan resulted, respectively, in a 25 and 60% reduction of acetic acid-induced writhings in comparison to pure drug, which, instead, was statistically ineffective as compared to the control group. Moreover, the 3/7 (w/w) drug-chitosan coground product demonstrated an antiwrithing potency 2.4 times higher than the coground with PVP. Thus, the direct-compression properties and antiulcerogenic activity, combined with the demonstrated solubilizing power and analgesic effect enhancer ability towards the drug, make chitosan particularly suitable for developing a reduced-dose fast-release solid oral dosage form of naproxen. PMID:14729084

  14. Sonolytic decomposition of poly(vinylpyrrolidone), ethanol, and tetranitromethane in aqueous solution

    SciTech Connect

    Gutierrez, M.; Henglein, A.

    1988-05-19

    Aqueous solutions of poly(vinylpyrrolidone), PVP (as nonvolatile solute), ethanol (as volatile and soluble solute), and tetranitromethane, TNM (as volatile and almost insoluble solute), were irradiated under argon with 300-kHz ultrasound at an intensity of 2 W x cm/sup -2/. In all three cases, products were observed (such as CH/sub 4/, C/sub 2/H/sub 4/, C/sub 2/H/sub 6/, CO, and CO/sub 2/ from PVP and ethanol, and NO/sub 2//sup -/, NO/sub 3//sup -/, N/sub 2/, CO, and CO/sub 2/ from TNM), the formation of which can only be understood in terms of pyrolysis in or close to the cavitation bubbles. More pyrolysis products are formed from PVP than bonds are broken in the main chain by hydrodynamic shear forces in the neighborhood of cavitation bubbles. The decomposition of TNM is one of the fastest sonochemical reaction. The yields were determined at various solute concentrations, and it was concluded from these data that (1) the extent of pyrolysis depends on the rate of dehydration of solute molecules, this rate increasing with their hydrophobicity, and (2) pyrolysis might be supported by free-radical attack.

  15. Polyvinylpyrrolidone/polyvinyl butyral composite as a stable binder for castable supercapacitor electrodes in aqueous electrolytes

    NASA Astrophysics Data System (ADS)

    Aslan, M.; Weingarth, D.; Herbeck-Engel, P.; Grobelsek, I.; Presser, V.

    2015-04-01

    Mixtures of polyvinylpyrrolidone/polyvinyl butyral (PVP/PVB) are attractive binders for the preparation of carbon electrodes for aqueous electrolyte supercapacitors. The use of PVP/PVB offers several key advantages: They are soluble in ethanol and can be used to spray coat or drain cast activated carbon (AC) electrodes directly on a current collector. Infrared spectroscopy and contact angle measurements show that the PVP-to-PVB ratio determines the degree of binder hydrophilicity. Within our study, the most favorable performance was obtained for AC electrodes with a composition of AC + 1.5 mass% PVP + 6.0 mass% PVB; such electrodes were mechanically stabile and water resistant with a PVP release of less than 5% of total PVP while PVB itself is water insoluble. Compared to when using PVDF, the specific surface area (SSA) of the assembled electrodes was 10% higher, indicating a reduced pore blocking tendency. A good electrochemical performance was observed in different aqueous electrolytes for composite electrodes with the optimized binder composition: 160 F g-1 at 1 A g-1 for 1 M H2SO4 and 6 M KOH and 120 F g-1 for 1 M NaCl. The capacitance was slightly reduced by 2.5% after cycling to 1.2 V with 1.28 A g-1 in 1 M NaCl for 10,000 times.

  16. Silver-assisted chemical etching on silicon with polyvinylpyrrolidone-mediated formation of silver dendrites.

    PubMed

    Chen, Chia-Yun; Hsiao, Po-Hsuan

    2015-02-23

    Metal-assisted chemical etching (MaCE) on silicon (Si)-mediated by polyvinylpyrrolidone (PVP)-is systematically investigated herein. It is found that the morphologies and crystallographic natures of the grown silver (Ag) dendrites can be significantly modulated, with the presence of PVP in the MaCE process leading to the formation of faceted Ag dendrites preferentially along the (111) crystallographic phase, rather than along the (200) phase. Further explorations of the PVP-mediated effect on Si etching are also revealed. In contrast to the aligned Si nanowires formed by MaCE without PVP addition, only distributed nanopores with sizes of 200 to 400 nm appear on the Si surfaces in the presence of PVP. The origin of surface polishing on Si in the PVP-mediated MaCE process can be attributed to the distinct transport pathway of holes supplied by the Ag(+) ions, where the holes are injected directly into the primary Ag seeds, rather than through Ag dendrites, thus leading to the isotropic etching of the Si surface. PMID:25521287

  17. Physicochemical characterisation and biological evaluation of polyvinylpyrrolidone-iodine engineered polyurethane (Tecoflex(®)).

    PubMed

    Khandwekar, Anand P; Doble, Mukesh

    2011-05-01

    Bacterial adhesion and encrustation are the known causes for obstruction or blockage of urethral catheters and ureteral stents, which often hinders their effective use within the urinary tract. In this in vitro study, polyvinylpyrrolidone-iodine (PVP-I) complex modified polyurethane (Tecoflex(®)) systems were created by physically entrapping the modifying species during the reversible swelling of the polymer surface region. The presence of the PVP-I molecules on this surfaces were verified by ATR-FTIR, AFM and SEM-EDAX analysis, while wettability of the films was investigated by water contact angle measurements. The modified surfaces were investigated for its suitability as a urinary tract biomaterial by comparing its lubricity and ability to resist bacterial adherence and encrustation with that of base polyurethane. The PVP-I modified polyurethane showed a nanopatterned surface topography and was highly hydrophilic and more lubricious than control polyurethane. Adherence of both the gram positive Staphylococcus aureus (by 86%; **P < 0.01) and gram-negative Pseudomonas aeruginosa (by 80%; *P < 0.05) was significantly reduced on the modified surfaces. The deposition of struvite and hydroxyapatite the major components of urinary tract encrustations were significantly less on PVP-I modified polyurethane as compared to base polyurethane, especially reduction in hydroxyapatite encrustation was particularly marked. These results demonstrated that the PVP-I entrapment process can be applied on polyurethane in order to reduce/lower complications associated with bacterial adhesion and deposition of encrustation on polyurethanes. PMID:21437640

  18. Polyvinylpyrrolidone as binder for castable supercapacitor electrodes with high electrochemical performance in organic electrolytes

    NASA Astrophysics Data System (ADS)

    Aslan, M.; Weingarth, D.; Jäckel, N.; Atchison, J. S.; Grobelsek, I.; Presser, V.

    2014-11-01

    Polyvinylpyrrolidone (PVP) is presented as a "greener" alternative to commonly used supercapacitor binders, namely polyvinylidenedifluoride (PVDF) or polytetrafluoroethylene (PTFE). The key advantages of using PVP are that it is non-toxic and soluble in ethanol and it can be used to spray coat or drain cast activated carbon (AC) electrodes directly on a current collector such as aluminum foil - in contrast to PTFE that requires rolling or PVDF that requires toxic N-methylpyrrolidone (NMP). The electrodes with the best mechanical stability incorporated 3.5 mass% of 1.300.000 g mol-1 PVP. Compared to PTFE or PVDF, the resulting pore volume was significantly higher and the specific surface area significantly larger when using PVP (normalized to the amount of AC). A good electrochemical performance was observed in organic electrolytes for AC-PVP electrodes: 112 or 97 F g-1 at 0.1 A g-1 in 1 M TEA-BF4 in propylene carbonate or acetonitrile, respectively. The performance stability was comparable to PTFE-bound electrodes when adjusting the maximum cell voltage to 2.5 V while preserving the manufacturing features of PVDF-AC films. (Electro)chemical stability is shown by electrochemical testing and infrared vibrational spectroscopy for propylene carbonate and acetonitrile.

  19. Development of Itraconazole Liquisolid Compact: Effect of Polyvinylpyrrolidone on the Dissolution Properties.

    PubMed

    Gong, Wei; Wang, Yuli; Sun, Lei; Yang, Jiahui; Shan, Li; Yang, Meiyan; Gao, Chunsheng

    2016-01-01

    The aim of this work was to utilize the liquisolid technique to enhance dissolution of itraconazole (ITZ). Liquisolid tablets of ITZ were formulated by using N-methyl-2-pyrrolidone as liquid vehicle, polyvinylpyrrolidone (PVP) as a precipitation inhibitor and magnesium aluminometasilicate Neusilin® as a carrier and coating material. The effect of PVP level on stability of liquid medication, physicomechnanical properties and dissolution rate of liquisolid compacts was studied in detail. The crystallinity of formulated drug and the interaction between excipients were examined by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). All the liquisolid tablets showed higher drug dissolution rates than the conventional, directly compressed tablets. The flowability of liquisolid powders was slightly improved as the proportion of PVP in ITZ-NMP mixture increased. Moreover, the stability of liquid medication and wetting ability of liquisolid tablets were improved by PVP. The presence of low amount of PVP (≤ 1%) in liquisolid formulation could enhance dissolution of ITZ liquisolid tablets, whereas the percentage of PVP over 5% decreased the dissolution of ITZ from liquisolid tablets. Both DSC and XRPD suggested reduction or loss of ITZ crystallinity upon liquisolid formulations indicating that the drug was almost solubilized and molecularly dispersed with excipients within the liquisolid matrix. It could be shown that increased solubility, wetting properties and surface area available for dissolution contributed to the improvement of the dissolution of ITZ from liquisolid tablets. PMID:26882116

  20. The Role of Polyvinylpyrrolidone in Hydrothermally Synthesized Ag/ZnO Nanocomposites and Their Photocatalytic Activities.

    PubMed

    Mavrič, Tina; Emin, Saim; Valant, Matjaž; Peng, Wenqin; Stangar, Urkaška Lavrenčič

    2015-09-01

    Here we present a simple hydrothermal route for the preparation of photoactive ZnO and Ag/ZnO nanoparticles (NPs) synthesized in the presence and absence of polyvinylpyrrolidone (PVP). The low temperature synthesis is carried out in ethylene glycol (EG) medium at 180 degrees C, where EG is used as a reducing agent for the Ag+ ions. PVP is exploited as a size confining matrix for the Ag NPs. The present synthetic protocol allows the preparation of ZnO nanorods (NRs) with typical lengths of -200 nm and Ag/ZnO NPs with typical sizes of -100 nm. The photocatalytic activity of the as-prepared nanomaterials was tested for degradation of model pollutant methyl orange (MO) dye and terephthalic acid (TPA). We found that the Ag/ZnO NPs synthesized in PVP showed higher photoactivity than the commercial TiO2 (P25) powder or ZnO and Ag/ZnO NPs synthesized without PVP. PMID:26716210

  1. Monodisperse polyvinylpyrrolidone-coated CoFe2O4 nanoparticles: Synthesis, characterization and cytotoxicity study

    NASA Astrophysics Data System (ADS)

    Wang, Guangshuo; Ma, Yingying; Mu, Jingbo; Zhang, Zhixiao; Zhang, Xiaoliang; Zhang, Lina; Che, Hongwei; Bai, Yongmei; Hou, Junxian; Xie, Hailong

    2016-03-01

    In this study, monodisperse cobalt ferrite (CoFe2O4) nanoparticles were prepared successfully with various additions of polyvinylpyrrolidone (PVP) by sonochemical method, in which PVP served as a stabilizer and dispersant. The effects and roles of PVP on the morphology, microstructure and magnetic properties of the obtained CoFe2O4 were investigated in detail by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and superconducting quantum interference device (SQUID). It was found that PVP-coated CoFe2O4 showed relatively well dispersion with narrow size distribution. The field-dependent magnetization curves indicated superparamagnetic behavior of PVP-coated CoFe2O4 with moderate saturation magnetization and hydrophilic character at room temperature. More importantly, the in vitro cytotoxicity testing exhibited negligible cytotoxicity of as-prepared PVP-CoFe2O4 even at the concentration as high as 150 μg/mL after 24 h treatment. Considering the superparamagnetic properties, hydrophilic character and negligible cytotoxicity, the monodisperse CoFe2O4 nanoparticles hold great potential in a variety of biomedical applications.

  2. Synergy Between Polyvinylpyrrolidone-Coated Silver Nanoparticles and Azole Antifungal Against Drug-Resistant Candida albicans.

    PubMed

    Sun, Lingmei; Liao, Kai; Li, Yiping; Zhao, Lei; Liang, Sai; Guo, Dan; Hu, Jun; Wang, Dayong

    2016-03-01

    In the clinical practice, resistance of Candida albicans to antifungal agents has frequently emerged. Silver-nanoparticles (Ag-NPs) have been demonstrated to have the antifungal property. We investigated the potential for synergy between polyvinylpyrrolidone (PVP)-coated Ag-NPs and azole antifungal, such as fluconazole or voriconazole, against drug-resistant C. albicans strain CA10. When antifungal agent was examined alone, fluconazole and voriconazole did not kill drug-resistant C. albicans, and PVP-coated Ag-NPs had only the moderate killing ability. In contrast, the combinational treatment of PVP-coated Ag-NPs with fluconazole or voriconazole was effective in being against the drug-resistant C. albicans. After the combinational treatment, we detected the disruption of cell membrane integrity, the tendency of PVP-coated Ag-NPs to adhere to cell membrane, and the inhibition of budding process. Moreover, after the combinational treatment, the defects in ergosterol signaling and efflux pump functions were detected. Our results suggest that the combinational use of engineered nanomaterials (ENMs), such as PVP-coated Ag-NPs, with the conventional antifungal may be a viable strategy to combat drug-resistant fungal infection. PMID:27455637

  3. Materials with controlled mesoporosity derived from synthetic polyvinylpyrrolidone-clay composites.

    SciTech Connect

    Carrado, K. A.; Xu, L.; Chemistry

    1999-01-01

    Mesoporous synthetic clays (MSCs) are obtained when polymer-containing silicate gels are hydrothermally crystallized to form layered magnesium silicate hectorite clays containing polymers that are incorporated in situ. In this in situ technique, interlayer intercalation of different polymers over broad molecular weight and concentration ranges is achieved. The polymer loading of synthesized composites is determined by thermal analysis, and the basal spacing changes resulting from different levels of polymer intercalation are monitored by X-ray powder diffraction (XRD). In some cases, intercalation occurs to such a degree as to delaminate the layers and cause loss of stacking registry. Polyvinylpyrrolidone (PVP) of several average molecular weights ranging from 10x10{sup 3}-1.3x10{sup 6}, in loadings varying from 10 to 20 wt.%, were used. The organic polymer template molecules were removed from synthetic polymer-clay complexes via calcination. Pore radii, surface areas and pore volumes of the resulting porous inorganic networks (MSCs) were then measured. A direct correlation between both PVP Mw and polymer loading on the radius of the average pore was found, which varied from 21-45 Angstroms.

  4. Design and fabrication of ultrafine piezoelectric composites.

    PubMed

    Yin, J; Lukacs, M; Harasiewicz, K A; Foster, F S

    2005-01-01

    Making fine scale (< 20 microm) piezoelectric composites for high frequency (> 50 MHz) ultrasound transducers remains challenging. Interdigital phase bonding (IPhB), described in this paper, presents a new technique developed to make piezoelectric composites at the ultrafine scale using a conventional dicing saw. Using the IPhB technique, a composite structure with a pitch that is less than the dicing saw blade thickness can be created. The approach is flexible enough to make composites of different combination of pitch and volume ratio. Using a conventional dicing saw with a 50 microm thick blade, composite with a 25 microm pitch and a volume ratio of 61 percent are fabricated. Such a composite is suitable for fabrication of ultrasonic transducers and arrays with central frequencies of up to 85 MHz. Single element transducers working at central frequencies of 50-60 MHz were made of these composites as a mean to characterize the acoustic performance. Measurement results of the transducers show that the longitudinal electromechanical coupling coefficient is greater than 0.6 and that there are no noticeable lateral resonances in the frequency range of 55-150 MHz. Design criteria for fine scale elements are also discussed based on theoretical results from finite element analysis (FEA). PMID:16003926

  5. Toronto Residents' Exposure to Ultrafine Particles

    NASA Astrophysics Data System (ADS)

    Sabaliauskas, Kelly Maria

    In urban areas, ultrafine particles (UFP: defined as particulate matter with diameters less than 100nm) are emitted in significant quantities from vehicles and form through a complex series of secondary reactions in the atmosphere. Large uncertainties surrounding the long-term behaviour and spatial distribution of UFP in urban areas have been a significant obstacle for exposure assessment. This research examined one of the longest existing urban UFP data sets, collected at a roadside location in downtown Toronto. Between 2006 and 2011, the concentration of particles with diameters <50nm and 50-100nm decreased by 21% and 17%, respectively. This reduction in concentration was attributed to changes in the vehicle fleet and reduced usage of coal-fired power plants for electricity generation. In addition, this research found that the shape of the particle size distribution exhibited distinct temporal and spatial behaviour suggesting that a single monitoring station does not provide sufficient information about UFP for an entire urban area. This investigation also produced a land-use regression model that was used to estimate the range of concentrations that exist across Toronto during the summer months. The highest concentrations were consistently observed near the downtown core and around highways and industrial areas. Finally, this work provides a foundation for future field studies in Toronto.

  6. Preparation and dispersive mechanism of highly dispersive ultrafine silver powder

    NASA Astrophysics Data System (ADS)

    Guo, Guiquan; Gan, Weiping; Luo, Jian; Xiang, Feng; Zhang, Jinling; Zhou, Hua; Liu, Huan

    2010-09-01

    Using ascorbic acid as the reducing agent, AgNO 3 as the source of Ag, the ultrafine silver powder was prepared by liquid-phase reduction method. The optimal conditions to prepare the ultrafine silver powder were obtained by studying the effects of following factors, such as the selection of dispersant, the doses of dispersant and pH, on the dispersibility of silver powder under other constant conditions. The pure ultrafine silver powder with quasi-spherical shape and mean size of 1.15 μm was synthesized under the optimal conditions of polyvinyl alcohol (PVA) as disperser, PVA/AgNO 3 mass ratio of 4:100 and pH 7 while maintaining other conditions exactly in the same circumstances, such as AgNO 3 concentration of 0.20 mol L -1, ascorbic acid concentration of 0.15 mol L -1 and reaction temperature of 40 °C. The ultrafine silver powder was characterized by SEM and XRD. And a PVA dispersive mechanism for preparing highly dispersive ultrafine silver powder, proved by the ultraviolet spectra, is that PVA absorbed on the surface of silver particles by coordination bond preventing the silver particles from diffusion and aggregation. In addition, the steric effect may help to reduce aggregation.

  7. Polymer degradation and ultrafine particles - Potential inhalation hazards for astronauts

    NASA Technical Reports Server (NTRS)

    Ferin, J.; Oberdoerster, G.

    1992-01-01

    To test the hypothesis that exposure to ultrafine particles results in an increased interstiatilization of the particles which is accompanied by an acute pathological inflammation, rats were exposed to titanium dioxide (TiO2) particles by intratracheal instillation and by inhalation. Both acute intratracheal instillation and subchronic inhalation studies on rats show that ultrafine TiO2 particles access the pulmonary interstitium to a larger extent than fine particles and that they elicit an inflammatory response as indicated by PMN increase in lavaged cells. The release of ultrafine particles into the air of an enclosed environment from a thermodegradation event or from other sources is a potential hazard for astronauts. Knowing the mechanisms of action is a prerequisite for technical or medical countermeasures.

  8. Novel technologies for the production of ultrafine coal liquefaction catalysts

    SciTech Connect

    Matson, D.W.; Linehan, J.C.; Fulton, J.L.; Bean, R.M.

    1991-10-01

    Unusual materials processing technologies offer the potential for forming ultrafine iron-bearing particles suitable for coal liquefaction catalysis. Two such technologies currently under development at the Pacific Northwest Laboratory are the rapid expansion of supercritical fluid solutions (RESS) process and the precipitation of ultrafine particles in reverse micelle solutions. The RESS process involves expansion of dilute solutions through a small orifice from pressures and temperatures at which they exist as supercritical fluids, to ambient or near ambient conditions such that the post-expansion solvent exists solely in the gaseous phase. The abrupt drop in solvent density and the resulting solute particle nucleation and growth which occur during a RESS expansion promote formation of an ultrafine aerosol consisting of nanometer to micrometer scale solid solute particles. Precipitation of iron sulfides and iron oxides in reverse micelle systems as an alternative route to nanometer scale particle formation is also discussed.

  9. Cellular activity of bioactive nanograined/ultrafine-grained materials.

    PubMed

    Misra, R D K; Thein-Han, W W; Mali, S A; Somani, M C; Karjalainen, L P

    2010-07-01

    Our recent electron microscopy study on biomimetic nanostructured coatings on nanograined/ultrafine-grained (NG/UFG) substrates [Mater Sci Eng C 2009;29:2417-27] indicated that electrocrystallized nanohydroxyapatite (nHA) on phase-reversion-induced NG/UFG substrates exhibited a vein-type interconnected and fibrillar structure that closely mimicked the hierarchical structure of bone. The fibrillar structure on NG/UFG substrate is expected to be more favorable for cellular response than a planar surface. In contrast, hydroxyapatite (HA) coating on coarse-grained (CG) substrate more closely resembled a film rather than a fibrillar structure. Inspired by the differences in the structure of HA coating, we describe here the cell-substrate interactions of pre-osteoblasts (MC 3T3-E1) on bioactive NG/UFG and CG austenitic stainless steel substrates. NG/UFG austenitic stainless steel was obtained by a novel controlled phase-reversion annealing of cold-deformed austenite. This example provides an illustration of how a combination of cellular and molecular biology, materials science and engineering can advance our understanding of cell-substrate interactions. Interestingly, the cellular response of nanohydroxyapatite (nHA)-coated NG/UFG substrate demonstrated superior cytocompatibility, improved initial cell attachment, higher viability and proliferation, and well-spread morphology in relation to HA-coated CG substrate and their respective uncoated (bare) counterparts as implied by fluorescence and electron microscopy and MTT assay. Similar conclusions were derived from an immunofluorescence study that involved examination of the expression levels of vinculin focal adhesion contacts associated with dense actin stress fibers and fibronectin, protein analysis through protein bands in SDS-PAGE, and quantitative total protein assay. The enhancement of cellular response followed the sequence: nHA-coated NG/UFG>nHA-coated CG>NG/UFG>CG substrates. The outcomes of the study are

  10. Pelletization studies of ultra-fine clean coal

    SciTech Connect

    Mehta, R.H.; Parekh, B.K.

    1995-10-01

    Handling of fine coal is an importance issue for coal as well as the utility industry. Reconstitution in the form of a pellet or briquette would be desirable if it could be done economically. This paper evaluates the effectiveness of three binders e.g., asphalt-emulsion, corn starch and Brewex, in forming pellets of ultra-fine clean coal. It was fond that asphalt emulsion and corn starch were not effective binders for ultra-fine clean coal, however, Brewex provided excellent quality of pellets, which exceeded all the minimum quality requirements of coal pellets.

  11. Focusing particle concentrator with application to ultrafine particles

    DOEpatents

    Hering, Susanne; Lewis, Gregory; Spielman, Steven R.

    2013-06-11

    Technology is presented for the high efficiency concentration of fine and ultrafine airborne particles into a small fraction of the sampled airflow by condensational enlargement, aerodynamic focusing and flow separation. A nozzle concentrator structure including an acceleration nozzle with a flow extraction structure may be coupled to a containment vessel. The containment vessel may include a water condensation growth tube to facilitate the concentration of ultrafine particles. The containment vessel may further include a separate carrier flow introduced at the center of the sampled flow, upstream of the acceleration nozzle of the nozzle concentrator to facilitate the separation of particle and vapor constituents.

  12. A new and superior ultrafine cementitious grout

    SciTech Connect

    Ahrens, E.H.

    1997-04-01

    Sealing fractures in nuclear waste repositories concerns all programs investigating deep burial as a means of disposal. Because the most likely mechanism for contaminant migration is by dissolution and movement through groundwater, sealing programs are seeking low-viscosity sealants that are chemically, mineralogically, and physically compatible with the host rock. This paper presents the results of collaborative work directed by Sandia National Laboratories (SNL) and supported by Whiteshell Laboratories, operated by Atomic Energy of Canada, Ltd. The work was undertaken in support of the Waste Isolation Pilot Plant (WIPP), an underground nuclear waste repository located in a salt formation east of Carlsbad, NM. This effort addresses the technology associated with long-term isolation of nuclear waste in a natural salt medium. The work presented is part of the WIPP plugging and sealing program, specifically the development and optimization of an ultrafine cementitious grout that can be injected to lower excessive, strain-induced hydraulic conductivity in the fractured rock termed the Disturbed Rock Zone (DRZ) surrounding underground excavations. Innovative equipment and procedures employed in the laboratory produced a usable cement-based grout; 90% of the particles were smaller than 8 microns and the average particle size was 4 microns. The process involved simultaneous wet pulverization and mixing. The grout was used for a successful in situ test underground at the WIPP. Injection of grout sealed microfractures as small as 6 microns (and in one rare instance, 3 microns) and lowered the gas transmissivity of the DRZ by up to three orders of magnitude. Following the WIPP test, additional work produced an improved version of the grout containing particles 90% smaller than 5 microns and averaging 2 microns. This grout will be produced in dry form, ready for the mixer.

  13. Preparation and characterization of solid dispersion freeze-dried efavirenz – polyvinylpyrrolidone K-30

    PubMed Central

    Fitriani, Lili; Haqi, Alianshar; Zaini, Erizal

    2016-01-01

    The aim of this research is to prepare and characterize solid dispersion of efavirenz – polyvinylpyrrolidone (PVP) K-30 by freeze drying to increase its solubility. Solid dispersion of efavirenz – PVP K-30 was prepared by solvent evaporation method with ratio 2:1, 1:1, and 1:2 and dried using a freeze dryer. Characterizations were done by scanning electron microscopy (SEM), powder X-ray diffraction analysis, differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectroscopy. Solubility test was carried out in CO2-free distilled water, and efavirenz assay was conducted using high-performance liquid chromatography with acetonitrile:acetic acid (80:20) as the mobile phases. Powder X-ray diffractogram showed a decrease in the peak intensity, which indicated the crystalline altered to amorphous phase. DTA thermal analysis showed a decrease in the melting point of the solid dispersion compared to intact efavirenz. SEM results indicated the changes in the morphology of the crystal into an amorphous form compared to pure components. FT-IR spectroscopy analysis showed a shift wavenumber of the spectrum efavirenz and PVP K-30. The solubility of solid dispersion at ratio 2:1, 1:1, and 1:2 was 6.777 μg/mL, 6.936 μg/mL, and 14,672 μg/mL, respectively, whereas the solubility of intact efavirenz was 0.250 μg/mL. In conclusion, the solubility of solid dispersion increased significantly (P < 0.05). PMID:27429930

  14. BisGMA-polyvinylpyrrolidone blend based nanocomposites reinforced with chitosan grafted f-multiwalled carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Praharaj, A.; Behera, D.; Rath, P.; Bastia, T. K.; Rout, A. K.

    In this work, initially a non-destroyable surface grafting of acid functionalized multiwalled carbon nanotubes (f-MWCNTs) with biopolymer chitosan (CS) was carried out using glutaraldehyde as a cross-linking agent via the controlled covalent deposition method which was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Then, BisGMA (bisphenol-A glycidyldimethacrylate)-polyvinylpyrrolidone (PVP) blend was prepared (50:50 wt%) by a simple sonication method. The CS grafted f-MWCNTs (CS/f-MWCNTs) were finally dispersed in BisGMA-PVP blend (BGP50) system in different compositions i.e. 0, 2, 5 and 7 wt% and pressed into molds for the fabrication of reinforced nanocomposites which were characterized by SEM. Nanocomposites reinforced with 2 wt% raw MWCNTs and acid f-MWCNTs were also fabricated and their properties were studied in detail. The results of comparative study report lower values of the investigated properties in nanocomposites with 2 wt% raw and f-MWCNTs than the one with 2 wt% CS/f-MWCNTs proving it to be a better reinforcing nanofiller. Further, the mechanical behavior of the nanocomposites with various CS/f-MWCNTs content showed a dramatic increase in Young's Modulus, tensile strength, impact strength and hardness along with improved dynamic mechanical, thermal and electrical properties at 5 wt% content of CS/f-MWCNTs. The addition of CS/f-MWCNTs also resulted in reduced corrosion and swelling properties. Thus, the fabricated nanocomposites with optimum nanofiller content could serve as low cost and light weight structural, thermal and electrical materials compatible in various corrosive and solvent based environments.

  15. Visible-light photochromic nanocomposite thin films based on polyvinylpyrrolidone and polyoxometalates supported on clay minerals

    NASA Astrophysics Data System (ADS)

    Wang, Xiang-yu; Dong, Qi; Meng, Qing-ling; Yang, Jun-Yan; Feng, Wei; Han, Xiang-kui

    2014-10-01

    A novel reversible photochromic nanocomposite film was prepared by entrapping phosphomolybdic acid supported on the sodium bentonite (PMoA/Na-MMT) into polyvinylpyrrolidone (PVPd). The microstructure, thermal stability, photochromic behavior and mechanism of the hybrid film were investigated. Fourier transform infrared spectroscopy (FT-IR) results illustrated that the Keggin geometry of polyoxometalates (PMoA) and organic groups of PVPd were still preserved inside the composites and non-covalent bond interaction was built between PMoA/Na-MMT and PVPd polymer matrix. Transmission electron microscopy (TEM) image showed that PMoA nanoparticles were finely dispersed in Na-MMT which exhibited fine stratified structure. Atomic force microscopy (AFM) images indicated that the surface topography of polymeric matrix changed after adding PMoA/Na-MMT, and the surface appearance of nanocomposite film was different before and after visible-light irradiation. The stability of the hybrid film and the effect of the perturbation of Na-MMT on the stability were determined by means of the thermogravimetric analysis (TG) and differential thermal analysis (DTA). Irradiated with visible light, the ultraviolet--visible spectra (UV-vis) showed that the hybrid films changed from colorless to blue and could recover the colorless state gradually in air, where oxygen played an important role during the bleaching process. The hybrid films exhibited excellent bleaching ability during the heating. According to the X-ray photoelectron spectroscopy (XPS) analysis, the appearance of Mo5+ species indicated the photo-reduction reaction between PMoA/Na-MMT and PVPd matrix occurred according to the proton transfer mechanism, and the photochromic reactions were found to exhibit first-order kinetics.

  16. Effect of pH and biological media on polyvinylpyrrolidone-capped silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Lau, Chew Ping; Abdul-Wahab, Mohd Firdaus; Jaafar, Jafariah; Chan, Giek Far; Rashid, Noor Aini Abdul

    2016-07-01

    Toxicity and mobility of silver nanoparticles (AgNPs) vary in different surrounding environments. Surface coatings or functionalization, temperature, pH, dissolved oxygen concentration, nanoparticle concentration, the presence of organic matter, and ionic strength are factors which dictate the transformation of AgNPs in terms of aggregation and stabilization. Thus, the purpose of this study is to investigate the behavior of polyvinylpyrrolidone (PVP)-capped AgNPs at different pHs (pH 2 to 10) and in different biological media (0.1 M phosphate buffer, nutrient broth, P5 and modified P5 media) analyzed using UV-Vis spectroscopy and zeta potential analyzer. The PVP-capped AgNPs changed its behavior in the presence of varying media, after 24 h incubation with shaking at 200 rpm at 30°C. No aggregation was observed at pH 4 to 10, but distinctive at very low pH of 2. Low pH further destabilized PVP-capped AgNPs after 24 h of incubation. High ionic strength 0.1 M phosphate buffer also resulted in slow aggregation and eventually destabilized the nanoparticles. Biological media (nutrient broth, P5 and modified P5 media) containing organic components caused aggregation of the PVP-capped AgNPs. The increase in glucose and nutrient broth concentrations led to increased aggregation. However, PVP-capped AgNPs stabilized after 24 h incubation in media containing a high concentration of glucose and nutrient broth. The results demonstrate that low pH value, high ionic strength and the content of the biological media can influence the stability of AgNPs. This provides information on the aggregation behavior of PVP-capped AgNPs and can possibly further predict the fate, transport as well as the toxicity of silver nanoparticles after being released into the aquatic environment.

  17. Induction of IgG memory responses with polyvinylpyrrolidone (PVP) is antigen dose dependent

    SciTech Connect

    Lite, H.S.; Braley-Mullen, H.

    1981-03-01

    Irradiated recipients of spleen cells from mice primed with a very low dose (0.0025 ..mu../g) of the thymus-independent (TI) antigen polyvinylpyrrolidone (PVP) produced PVP-specific IgG memory responses after secondary challenge with a T-dependent (TD) form of PVP, PVP-HRBC. The IgG memory responses induced by low doses of PVP were similar in magnitude to those induced by the TD antigen PVP-HRBC. The induction of IgG memory by the TI form of antigen was markedly dependent on the dose of PVP used to prime donor mice. Spleen cells from mice primed with an amount of PVP (0.25 ..mu..g) that induces an optimal primary IgM response did not produce significant IgG antibody after challenge with PVP-HRBC. The inability of higher doses of PVP to induce IgG memory may be due, at least in part, to the fact that such doses of PVP were found to induce tolerance in PVP-specific B cells and could suppress the induction of memory induced by PVP-HRBC. Low doses of PVP did not interfere with the induction of memory by PVP-HRBC. Expression of IgG memory responses in recipients of PVP-HRBC or low-dose PVP-primed cells was found to be T cell dependent. Moreover, only primed T cells could reconstitute the respnse of recipients of primed B cells, suggesting that the ability of PVP to induce IgG memory may be related to its ability to prime T helper cells. Expression of the IgG memory response in recipient mice also required the use of a TD antigen for secondary challenge, i.e., mice challenged with PVP did not develop IgG.

  18. Preparation and characterization of solid dispersion freeze-dried efavirenz - polyvinylpyrrolidone K-30.

    PubMed

    Fitriani, Lili; Haqi, Alianshar; Zaini, Erizal

    2016-01-01

    The aim of this research is to prepare and characterize solid dispersion of efavirenz - polyvinylpyrrolidone (PVP) K-30 by freeze drying to increase its solubility. Solid dispersion of efavirenz - PVP K-30 was prepared by solvent evaporation method with ratio 2:1, 1:1, and 1:2 and dried using a freeze dryer. Characterizations were done by scanning electron microscopy (SEM), powder X-ray diffraction analysis, differential thermal analysis (DTA), and Fourier transform infrared (FT-IR) spectroscopy. Solubility test was carried out in CO2-free distilled water, and efavirenz assay was conducted using high-performance liquid chromatography with acetonitrile:acetic acid (80:20) as the mobile phases. Powder X-ray diffractogram showed a decrease in the peak intensity, which indicated the crystalline altered to amorphous phase. DTA thermal analysis showed a decrease in the melting point of the solid dispersion compared to intact efavirenz. SEM results indicated the changes in the morphology of the crystal into an amorphous form compared to pure components. FT-IR spectroscopy analysis showed a shift wavenumber of the spectrum efavirenz and PVP K-30. The solubility of solid dispersion at ratio 2:1, 1:1, and 1:2 was 6.777 μg/mL, 6.936 μg/mL, and 14,672 μg/mL, respectively, whereas the solubility of intact efavirenz was 0.250 μg/mL. In conclusion, the solubility of solid dispersion increased significantly (P < 0.05). PMID:27429930

  19. Antioxidation Properties and Surface Interactions of Polyvinylpyrrolidone-Capped Zerovalent Copper Nanoparticles Synthesized in Supercritical Water.

    PubMed

    Morioka, Takuya; Takesue, Masafumi; Hayashi, Hiromichi; Watanabe, Masaru; Smith, Richard L

    2016-01-27

    Zerovalent copper nanoparticles (CuNPs) (diameter, 26.5 ± 9 nm) capped with polyvinylpyrrolidone (PVP) were synthesized in supercritical water at 400 °C and 30 MPa with a continuous flow reactor. The PVP-capped CuNPs were dispersed in distilled water, methanol, ethanol, 1-propanol, 2-propanol, butanol, and their mixed solvents to study their long-term stability. Temporal variation of UV-vis spectra and surface plasmon resonance were measured and showed that ethanol, the propanols, and butanol solvents provided varying degrees of oxidative protection for Cu(0). Fourier transform infrared spectroscopy showed that PVP adsorbed onto the surface of the CuNPs with a pyrrolidone ring of PVP even if the CuNPs were oxidized. Intrinsic viscosities of PVP were higher for solvents that provided antioxidation protection than those that give oxidized CuNPs. In solvents that provided Cu(0) with good oxidative protection (ethanol, the propanols, and butanol), PVP polymer chains formed large radii of gyration and coil-like conformations in the solvents so that they were arranged uniformly and orderly on the surface of the CuNPs and could provide protection of the Cu(0) surface against dissolved oxygen. In solvents that provided poor oxidative protection for Cu(0) (water, alcohol-water mixed solvents with 30% water), PVP polymer chains had globular-like conformations due to their relatively high hydrogen-bonding interactions and sparse adsorption onto the CuNP surface. Antioxidative properties of PVP-capped CuNPs in a solvent can be ascribed to the conformation of PVP polymer chains on the Cu(0) particle surface that originates from the interaction between polymer chains and its interaction with the solvent. PMID:26716468

  20. Effects of interphase regions on performance of carbon fiber reinforced thermoset composites

    SciTech Connect

    Lesko, J.J.; Case, S.W.; Reifsnider, K.L.

    1995-12-31

    The effects of systematically varied interphase materials on carbon fiber reinforced epoxy and vinyl ester matrix composites are under continuing investigation. Substantial differences in composite strength and fatigue durability have been observed between two composite material systems with epoxy matrices and contrasting interphases. The improvements were directly attributed to the application of a thermoplastic sizing miscible with the matrix resin, poly(vinylpyrrolidone), as opposed to a conventional epoxy sizing. In some cases, fiber dominated composite strength was improved by 50% and fatigue lives were increased by two orders of magnitude using the polyamide sizing. Distinct morphological differences resulted in the interphase regions using the different sizings, and thus, it was assumed that the local mechanical properties of the composites in this region were dissimilar. This work has now been extended to carbon fabric reinforced, vinyl ester/styrene matrix composites. Analogously, dramatically increased fatigue durability of these materials using poly(vinylpyrrolidone) sizings has also been observed.

  1. Development of silicon nitride composites with continuous fiber reinforcement

    SciTech Connect

    Starr, T.L.; Mohr, D.L.; Lackey, W.J.; Hanigofsky, J.A.

    1993-10-01

    The composites were fabricated using ultrafine Si powders prepared by attritor milling; the powders exhibits full conversion to Si nitride in < 3 h at {le} 1200 C (these conditions reduce degradation of the fibers compared to conventional). Effects of processing conditions on fiber properties and the use of fiber coatings to improve stability during processing as well as change the fiber-matrix interfacial properties were investigated. A duplex carbon-silicon carbide coating, deposited by CVD, reduced fiber degradation in processing, and it modified the fiber-matrix adhesion. Si nitride matrix composites were fabricated using reaction sintering, forming laminates, filament-wound plates, and tubes. In each case, an attritor milled Si powder slurry is infiltrated into ceramic fiber preforms or tows, which are then assembled to form a 3-D structure for reaction sintering. The resulting composites have properties comparable to chemical vapor infiltration densified composites, with reasonable strengths and graceful composite fracture behavior.

  2. EFFECTS OF CARBON ULTRAFINE PARTICLES ON HUMAN AIRWAY EPITHELIAL CELLS

    EPA Science Inventory

    One of the leading theories concerning the toxicology of ambient particulate matter (PM) attributes health effects associated with PM inhalation to ultrafine particles (UF). UF numbers dwarf those of fine and coarse particles present in the ambient air as a result of fossil fuel ...

  3. LASER DESORPTION IONIZATION OF ULTRAFINE AEROSOL PARTICLES. (R823980)

    EPA Science Inventory

    On-line analysis of ultrafine aerosol particle in the 12 to 150 nm size range is performed by
    laser desorption/ionization. Particles are size selected with a differential mobility analyzer and then
    sent into a linear time-of-flight mass spectrometer where they are ablated w...

  4. ULTRAFINE ASH AEROSOLS FROM COAL COMBUSTION: CHARACTERIZATION AND HEALTH EFFECTS

    EPA Science Inventory

    Ultrafine coal fly ash particles, defined here as those with diameters less than 0.5 micrometer, typically comprise less than 1% of the total fly ash mass. These particles are formed almost exclusively through ash vaporization, nucleation, and coagulation/condensation mechanisms,...

  5. Ultrafine and respirable particles in an automotive grey iron foundry.

    PubMed

    Evans, Douglas E; Heitbrink, William A; Slavin, Thomas J; Peters, Thomas M

    2008-01-01

    Ultrafine particle number and respirable particle mass concentrations were measured throughout an automotive grey iron foundry during winter, spring and summer using a particle concentration mapping procedure. Substantial temporal and spatial variability was observed in all seasons and attributed, in part, to the batch nature of operations, process emission variability and frequent work interruptions. The need for fine mapping grids was demonstrated, where elevations in particle concentrations were highly localized. Ultrafine particle concentrations were generally greatest during winter when incoming make-up air was heated with direct fire, natural gas burners. Make-up air drawn from roof level had elevated respirable mass and ultrafine number concentrations above ambient outdoor levels, suggesting inadvertent recirculation of foundry process emissions. Elevated respirable mass concentrations were highly localized on occasions (e.g. abrasive blasting and grinding), depended on the area within the facility where measurements were obtained, but were largely unaffected by season. Particle sources were further characterized by measuring their respective number and mass concentrations by particle size. Sources that contributed to ultrafine particles included process-specific sources (e.g. melting and pouring operations), and non-process sources (e.g. direct fire natural gas heating units, a liquid propane-fuelled sweeper and cigarette smoking) were additionally identified. PMID:18056626

  6. CARDIOVASCULAR RESPONSES TO ULTRAFINE CARBON PARTICLE EXPOSURES IN RATS

    EPA Science Inventory

    TD-02-042 (U. KODAVANTI) GPRA # 10108

    Cardiovascular Responses to Ultrafine Carbon Particle Exposures in Rats.
    V. Harder1, B. Lentner1, A. Ziesenis1, E. Karg1, L. Ruprecht1, U. Kodavanti2, A. Stampfl3, J. Heyder1, H. Schulz1
    GSF- Institute for Inhalation Biology1, I...

  7. DAILY MORTALITY AND FINE AND ULTRAFINE PARTICLES IN ERFURT, GERMANY

    EPA Science Inventory

    Dr H-Erich Wichmann and colleagues at the National Research Center for Environment and Health (GSF) in Neuherberg, Germany, prospec-tively studied the association of daily mortality data with the number and mass concentrations of ultra-fine and fine particles in Erfurt, Ger...

  8. Health hazards of ultrafine metal and metal oxide powders

    NASA Technical Reports Server (NTRS)

    Boylen, G. W., Jr.; Chamberlin, R. I.; Viles, F. J.

    1969-01-01

    Study reveals that suggested threshold limit values are from two to fifty times lower than current recommended threshold limit values. Proposed safe limits of exposure to the ultrafine dusts are based on known toxic potential of various materials as determined in particle size ranges.

  9. Polyvinylpyrrolidone (PVP)-assisted solvothermal synthesis of flower-like SrCO{sub 3}:Tb{sup 3+} phosphors

    SciTech Connect

    Xue, Yannan; Ren, Xiaolei; Zhai, Xuefeng; Yu, Min

    2012-02-15

    Graphical abstract: A simple solvothermal method for the synthesis of flower-like SrCO{sub 3}:Tb{sup 3+} phosphors with the assistance of polyvinylpyrrolidone (PVP, K30). Highlights: Black-Right-Pointing-Pointer Well-crystallized flower-like SrCO{sub 3}:Tb{sup 3+} phosphors could be easily prepared by a simple solvothermal method with the assistance of polyvinylpyrrolidone (PVP). Black-Right-Pointing-Pointer The amount of PVP and the reaction time have a strong effect on controlling the morphology and optical properties of SrCO{sub 3}:Tb{sup 3+} particles. Black-Right-Pointing-Pointer The main synthesizing process and the growth mechanism for the formation of final samples were proposed. -- Abstract: Well-crystallized flower-like SrCO{sub 3}:Tb{sup 3+} phosphors have been synthesized by an inexpensive and friendly solvothermal process using polyvinylpyrrolidone (PVP, K30) as an additive without further annealing treatment. X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), and field emission scanning electron microscopy (FESEM) as well as photoluminescence spectroscopy (PL) were used to characterize the resulting samples. The amount of PVP and the reaction time have strong effect on the morphology of the SrCO{sub 3}:Tb{sup 3+} particles. The results of XRD confirm the formation of a well-crystallized SrCO{sub 3} phase with an orthorhombic structure. The possible formation mechanism for flower-like SrCO{sub 3}:Tb{sup 3+} phosphor is proposed. The SrCO{sub 3}:Tb{sup 3+} phosphors show the characteristic {sup 5}D{sub 4}-{sup 7}F{sub J} (J = 6, 5, 4, 3) emission lines with green emission {sup 5}D{sub 4}-{sup 7}F{sub 5} (544 nm) as the most prominent group under ultraviolet excitation.

  10. Eu-doped BaTiO₃powder and film from sol-gel process with polyvinylpyrrolidone additive.

    PubMed

    García-Hernández, Margarita; García-Murillo, Antonieta; de J Carrillo-Romo, Felipe; Jaramillo-Vigueras, David; Chadeyron, Geneviève; De la Rosa, Elder; Boyer, Damien

    2009-09-01

    Transparent BaTiO(3):Eu(3+) films were prepared via a sol-gel method and dip-coating technique, using barium acetate, titanium butoxide, and polyvinylpyrrolidone (PVP) as modifier viscosity. BaTiO(3):Eu(3+) films ~500 nm thick, crystallized after thermal treatment at 700 masculineC. The powders revealed spherical and rod shape morphology. The optical quality of films showed a predominant band at 615 nm under 250 nm excitation. A preliminary luminescent test provided the properties of the Eu(3+) doped BaTiO(3). PMID:19865533

  11. Optimization of strength and ductility in nanotwinned ultrafine grained Ag: twin density and grain orientations

    SciTech Connect

    Ott, R. T.; Geng, J.; Besser, M. F.; Kramer, M. J.; Wang, Y. M.; Park, E. S.; LeSar, R.; King, A. H.

    2015-06-27

    Nanotwinned ultrafine grained Ag thick films with different twin densities and orientations have been synthesized by magnetron sputtering with a wide-range of deposition rates. The twin boundary (TB) spacings and orientations as well as the grain size for the different deposition conditions have been characterized by both synchrotron X-ray scattering and transmission electron microscopy (TEM). Structural characterization combined with uniaxial tensile tests of the free-standing films reveals a large increase in the yield strength for films deposited at high deposition rates without any accompanying change in the TB spacing – a behavior that is in contrast with what has been reported in the literature. We find that films deposited at lower deposition rates exhibit more randomly oriented grains with a lower overall twin density (averaged over all the grains) than the more heavily twinned grains with strong <111> fiber texture in the films deposited at higher deposition rates. The TB spacing in the twinned grains, however, does not show any significant dependence on the deposition rate. The dependence of the strength and ductility on the twin density and orientations can be described by two different soft deformation modes: 1) untwinned grains and 2) nanowinned grains that are not oriented with <111> along the growth direction. The untwinned grains provide relatively low resistance to slip, and thus decreased strength, while the nanotwinned grains that are not oriented with <111> along the growth direction are softer than nanotwinned grains that are oriented with <111> along the growth direction. We reveal that an ultrafine-grained (150-200 nm) structure consisting of a mixture of nanotwinned (~ 8-12 nm spacing) and untwined grains yields the best combination of high strength and uniform tensile ductility.

  12. Optimization of strength and ductility in nanotwinned ultrafine grained Ag: twin density and grain orientations

    DOE PAGESBeta

    Ott, R. T.; Geng, J.; Besser, M. F.; Kramer, M. J.; Wang, Y. M.; Park, E. S.; LeSar, R.; King, A. H.

    2015-06-27

    Nanotwinned ultrafine grained Ag thick films with different twin densities and orientations have been synthesized by magnetron sputtering with a wide-range of deposition rates. The twin boundary (TB) spacings and orientations as well as the grain size for the different deposition conditions have been characterized by both synchrotron X-ray scattering and transmission electron microscopy (TEM). Structural characterization combined with uniaxial tensile tests of the free-standing films reveals a large increase in the yield strength for films deposited at high deposition rates without any accompanying change in the TB spacing – a behavior that is in contrast with what has beenmore » reported in the literature. We find that films deposited at lower deposition rates exhibit more randomly oriented grains with a lower overall twin density (averaged over all the grains) than the more heavily twinned grains with strong <111> fiber texture in the films deposited at higher deposition rates. The TB spacing in the twinned grains, however, does not show any significant dependence on the deposition rate. The dependence of the strength and ductility on the twin density and orientations can be described by two different soft deformation modes: 1) untwinned grains and 2) nanowinned grains that are not oriented with <111> along the growth direction. The untwinned grains provide relatively low resistance to slip, and thus decreased strength, while the nanotwinned grains that are not oriented with <111> along the growth direction are softer than nanotwinned grains that are oriented with <111> along the growth direction. We reveal that an ultrafine-grained (150-200 nm) structure consisting of a mixture of nanotwinned (~ 8-12 nm spacing) and untwined grains yields the best combination of high strength and uniform tensile ductility.« less

  13. Surface area of particle administered versus mass in determining the pulmonary toxicity of ultrafine and fine carbon black: comparison to ultrafine titanium dioxide

    PubMed Central

    Sager, Tina M; Castranova, Vincent

    2009-01-01

    Background Nanoparticles are characterized by having a high surface area per mass. Particulate surface area has been reported to play an important role in determining the biological activity of nanoparticles. However, recent reports have questioned this relationship. This study was conducted to determine whether mass of particles or surface area of particles is the more appropriate dose metric for pulmonary toxicity studies. In this study, rats were exposed by intratracheal instillation to various doses of ultrafine and fine carbon black. At 1, 7, or 42 days post-exposure, inflammatory and cytotoxic potential of each particle type was compared on both a mass dosage (mg/rat) as well as an equal surface area dosage (cm2 of particles per cm2 of alveolar epithelium). In an additional study, the pulmonary responses to instillation of ultrafine carbon black were compared to equivalent particle surface area doses of ultrafine titanium dioxide. Results Ultrafine carbon black particles caused a dose dependent but transient inflammatory and cytotoxic response. On a mass basis, these responses were significantly (65 fold) greater than those for fine sized carbon black. However, when doses were equalized based on surface area of particles given, the ultrafine carbon black particles were only slightly (non-significantly) more inflammogenic and cytotoxic compared to the fine sized carbon black. At one day post-exposure, inflammatory potencies of the ultrafine carbon black and ultrafine titanium dioxide particles were similar. However, while the pulmonary reaction to ultrafine carbon black resolved with time, the inflammatory effects of ultrafine titanium dioxide were more persistent over a 42 day post-exposure period. Conclusion These results indicate that for low toxicity low solubility materials, surface area of particles administered rather than mass burden of particles may be a more appropriate dose metric for pulmonary toxicity studies. In addition, ultrafine titanium

  14. Flow and compaction behaviour of ultrafine coated ibuprofen.

    PubMed

    More, Parth K; Khomane, Kailas S; Bansal, Arvind K

    2013-01-30

    Good flow and compaction properties are prerequisites for successful compaction process. Apart from initial profile, mechanical properties of pharmaceutical powders can get modified during unit processes like milling. Milled powders can exhibit a wide range of particle size distribution. Further downstream processing steps like compaction can be affected by this differential particle size distribution. This has greatest implications for formulations like high dose drugs wherein the active pharmaceutical ingredient (API) contributes the maximum bulk in the final formulation. The present study assesses the impact of dry coating with ultrafine particles of same material, on the flow and compaction properties of the core material. Ibuprofen was selected as model drug as it has been reported to have poor mechanical properties. Ultrafine ibuprofen (average size 1.75 μm) was generated by Dyno(®) milling and was dry coated onto the core ibuprofen particles (average size 180 μm). Compaction studies were performed using a fully instrumented rotary tablet press. Compaction data was analyzed for compressibility, tabletability, compactibility profiles and Heckel plot. Dry coating of the ibuprofen exhibited greater compressibility and tabletability, at lower compaction pressure. However, at compaction pressure above 220 MPa, compressibility and tabletability of coated as well as uncoated materials were found to be similar. Heckel analysis also supported the above findings, as P(y) value of uncoated ibuprofen was found to be 229.49 MPa and for 2.0% ultrafine coated ibuprofen was found to be 158.53 MPa. Lower P(y) value of ultrafine coated ibuprofen indicated ease of plastic deformation. Superior compressibility and deformation behaviour of ultrafine coated ibuprofen attributed to increased interparticulate bonding area. This strategy can also be explored for improving tabletability of high dose poorly compressible drugs. PMID:23142495

  15. Genotoxicity of polyvinylpyrrolidone-coated silver nanoparticles in BEAS 2B cells.

    PubMed

    Nymark, Penny; Catalán, Julia; Suhonen, Satu; Järventaus, Hilkka; Birkedal, Renie; Clausen, Per Axel; Jensen, Keld Alstrup; Vippola, Minnamari; Savolainen, Kai; Norppa, Hannu

    2013-11-01

    Silver nanoparticles (AgNPs) are widely utilized in various consumer products and medical devices, especially due to their antimicrobial properties. However, several studies have associated these particles with toxic effects, such as inflammation and oxidative stress in vivo and cytotoxic and genotoxic effects in vitro. Here, we assessed the genotoxic effects of AgNPs coated with polyvinylpyrrolidone (PVP) (average diameter 42.5±14.5 nm) on human bronchial epithelial BEAS 2B cells in vitro. AgNPs were dispersed in bronchial epithelial growth medium (BEGM) with 0.6 mg/ml bovine serum albumin (BSA). The AgNP were partially well-dispersed in the medium and only limited amounts (ca. 0.02 μg Ag(+) ion/l) could be dissolved after 24h. The zeta-potential of the AgNPs was found to be highly negative in pure water but was at least partially neutralized in BEGM with 0.6 mg BSA/ml. Cytotoxicity was measured by cell number count utilizing Trypan Blue exclusion and by an ATP-based luminescence cell viability assay. Genotoxicity was assessed by the alkaline single cell gel electrophoresis (comet) assay, the cytokinesis-block micronucleus (MN) assay, and the chromosomal aberration (CA) assay. The cells were exposed to various doses (0.5-48 μg/cm(2) corresponding to 2.5-240 μg/ml) of AgNPs for 4 and 24 h in the comet assay, for 48 h in the MN assay, and for 24 and 48 h in the CA assay. DNA damage measured by the percent of DNA in comet tail was induced in a dose-dependent manner after both the 4-h and the 24-h exposures to AgNPs, with a statistically significant increase starting at 16 μg/cm(2) (corresponding to 60.8 μg/ml) and doubling of the percentage of DNA in tail at 48 μg/cm(2). However, no induction of MN or CAs was observed at any of the doses or time points. The lack of induction of chromosome damage by the PVP-coated AgNPs is possibly due to the coating which may protect the cells from direct interaction with the AgNPs, either by reducing ion leaching from the

  16. Pulmonary cellular effects in rats following aerosol exposures to ultrafine Kevlar aramid fibrils: evidence for biodegradability of inhaled fibrils.

    PubMed

    Warheit, D B; Kellar, K A; Hartsky, M A

    1992-10-01

    Previous chronic inhalation studies have shown that high concentrations of Kevlar fibrils produced fibrosis and cystic keratinizing tumors in rats following 2-year inhalation exposures. The current studies were undertaken to evaluate mechanisms and to assess the toxicity of inhaled Kevlar fibrils relative to other reference materials. Rats were exposed to ultrafine Kevlar fibers (fibrils) for 3 or 5 days at concentrations ranging from 600-1300 fibers/cc (gravimetric concentrations ranging from 2-13 mg/m3). A complete characterization of the fiber aerosol and dose was carried out. These measurements included gravimetric concentrations, mass median aerodynamic diameter, fiber number, and count median lengths and diameters of the aerosol. Following exposures, cells and fluids from groups of sham- and fiber-exposed animals were recovered by bronchoalveolar lavage (BAL). Alkaline phosphatase, lactate dehydrogenase (LDH), protein, and N-acetyl glucosaminidase (NAG) values were measured in BAL fluids at several time points postexposure. Alveolar macrophages were cultured and studied for morphology, chemotaxis, and phagocytosis by scanning electron microscopy. The lungs of additional exposed animals were processed for deposition, cell labeling, retained dose, and lung clearance studies, as well as fiber dimensions (from digested lung tissue), histopathology, and transmission electron microscopy. Five-day exposures to Kevlar fibrils elicited a transient granulocytic inflammatory response with concomitant increases in BAL fluid levels of alkaline phosphatase, NAG, LDH, and protein. Unlike the data from silica and asbestos exposures where inflammation persisted, biochemical parameters returned to control levels at time intervals between 1 week and 1 month postexposure. Macrophage function in Kevlar-exposed alveolar macrophages was not significantly different from sham controls at any time period. Cell labeling studies were carried out immediately after exposure, as well as 1

  17. Poly(vinylpyrrolidone) supported copper nanoclusters: glutathione enhanced blue photoluminescence for application in phosphor converted light emitting devices

    NASA Astrophysics Data System (ADS)

    Wang, Zhenguang; Susha, Andrei S.; Chen, Bingkun; Reckmeier, Claas; Tomanec, Ondrej; Zboril, Radek; Zhong, Haizheng; Rogach, Andrey L.

    2016-03-01

    Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(ii) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92.Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(ii) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92. Electronic supplementary information (ESI) available: The optical spectra of control experiments for Cu NC synthesis, optimization of the reaction conditions, and spectra for LEDs chips and blue LEDs. See DOI: 10.1039/c6nr00806b

  18. In-cabin ultrafine particle dynamics

    NASA Astrophysics Data System (ADS)

    Xu, Bin

    To assess the total human health risks associated with human exposure to ultrafine particle (UFP), the concentrations and fates of UFPs in the in-cabin atmospheres must be understood. In order to assess human exposure more accurately and further prevent adverse health effects from UFP exposure in the in-cabins, it is essential to gain insight into UFP transport dynamics between in-cabin and outside atmospheres and the factors that are able to affect them. In this dissertation, mathematical model are developed and formulated as tools to improve the understanding of UFP dynamics in the in-cabin atmosphere. Under three different ventilation conditions, (i) Fan off-recirculation (RC) off, (ii) Fan on-RC off, and (iii) Fan on-RC on, the average modeled UFP I/O ratios were found to be 0.40, 0.25 and 0.10, respectively, and agree with the experimental data very well. Then, analysis focused on how the factors, such as ventilation settings, vehicle speed, filtration, penetration, and deposition, affect I/O ratios in broader categories of vehicle cabin microenvironments. Ventilation is the only mechanical process of exchanging air between the in-cabin and the outside. Under condition (ii), I/O ratio that varies from 0.2 to 0.7 was proportional to the airflow rate in the range of 0-360 m3/h. Under condition (iii), the modeled I/O ratio was inversely proportional to the airflow rate from mechanical ventilation within the range of 0.15-0.45 depending on the particle size. Significant variability of the penetration factor (5˜20%) was found due to the pressure difference. A coefficient "B" was successfully introduced to account for the electric charge effect on penetration factors. The effect of penetration on the I/O ratio was then evaluated by substituting penetration factor into the model. Under condition (i), the modeled I/O ratios increased linearly, up to ˜20%, within the penetration factor range. Under condition (iii), the effect of penetration factor is less but still

  19. [Ultrafine particle number concentration and size distribution of vehicle exhaust ultrafine particles].

    PubMed

    Lu, Ye-qiang; Chen, Qiu-fang; Sun, Zai; Cai, Zhi-liang; Yang, Wen-jun

    2014-09-01

    Ultrafine particle (UFP) number concentrations obtained from three different vehicles were measured using fast mobility particle sizer (FMPS) and automobile exhaust gas analyzer. UFP number concentration and size distribution were studied at different idle driving speeds. The results showed that at a low idle speed of 800 rmin-1 , the emission particle number concentration was the lowest and showed a increasing trend with the increase of idle speed. The majority of exhaust particles were in Nuclear mode and Aitken mode. The peak sizes were dominated by 10 nm and 50 nm. Particle number concentration showed a significantly sharp increase during the vehicle acceleration process, and was then kept stable when the speed was stable. In the range of 0. 4 m axial distance from the end of the exhaust pipe, the particle number concentration decayed rapidly after dilution, but it was not obvious in the range of 0. 4-1 m. The number concentration was larger than the background concentration. Concentration of exhaust emissions such as CO, HC and NO showed a reducing trend with the increase of idle speed,which was in contrast to the emission trend of particle number concentration. PMID:25518646

  20. Highly efficient and controllable method to fabricate ultrafine metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Cai, Hongbing; Zhang, Kun; Yu, Xinxin; Pan, Nan; Tian, Yangchao; Luo, Yi; Wang, Xiaoping

    2015-11-01

    We report a highly efficient, controllable and scalable method to fabricate various ultrafine metallic nanostructures in this paper. The method starts with the negative poly-methyl-methacrylate (PMMA) resist pattern with line-width superior to 20 nm, which is obtained from overexposing of the conventionally positive PMMA under a low energy electron beam. The pattern is further shrunk to sub-10 nm line-width through reactive ion etching. Using the patter as a mask, we can fabricate various ultrafine metallic nanostructures with the line-width even less than 10 nm. This ion tailored mask lithography (ITML) method enriches the top-down fabrication strategy and provides potential opportunity for studying quantum effects in a variety of materials.

  1. Highly efficient and controllable method to fabricate ultrafine metallic nanostructures

    SciTech Connect

    Cai, Hongbing; Zhang, Kun; Pan, Nan E-mail: xpwang@ustc.edu.cn; Luo, Yi; Wang, Xiaoping E-mail: xpwang@ustc.edu.cn; Yu, Xinxin; Tian, Yangchao

    2015-11-15

    We report a highly efficient, controllable and scalable method to fabricate various ultrafine metallic nanostructures in this paper. The method starts with the negative poly-methyl-methacrylate (PMMA) resist pattern with line-width superior to 20 nm, which is obtained from overexposing of the conventionally positive PMMA under a low energy electron beam. The pattern is further shrunk to sub-10 nm line-width through reactive ion etching. Using the patter as a mask, we can fabricate various ultrafine metallic nanostructures with the line-width even less than 10 nm. This ion tailored mask lithography (ITML) method enriches the top-down fabrication strategy and provides potential opportunity for studying quantum effects in a variety of materials.

  2. Physicochemical characterization of Baizhi particles by ultrafine pulverization

    NASA Astrophysics Data System (ADS)

    Yang, Lian-Wei; Sun, Peng; Gai, Guo-Sheng; Yang, Yu-Fen; Wang, Yu-Rong

    2011-04-01

    Baizhi, as a medicinal plant, has been demonstrated to be useful for the treatment of aches and pains in China. The physicochemical characterization of Baizhi particles is greatly influenced by ultrafine pulverization. To study the physicochemical characterization of Baizhi, the raw plant material of Baizhi was ground to 6 μm particles by a high speed centrifugal sheering (HSCS) pulverizer. The micron particles were characterized by optical microscopy and scanning electron microscopy (SEM). Imperatorin is one of the active ingredients of Baizhi, and its extraction yield is determined to evaluate the chemical characterization of Baizhi powder. Imperatorin was analyzed by high performance liquid chromatography (HPLC). The results show that after ultrafine pulverization, the plant cell walls are broken into pieces and the extraction yield of imperatorin is increased by 11.93% compared with the normal particles.

  3. [Research on ultrafine grinding technology of improving dissolution rates of effective components in Sanjie Zhentong capsule].

    PubMed

    Xu, Zhong-kun; Gao, Jin; Qin, Jian-ping; Chen, Guang-bo; Wang, Zhen-zhong; Xiao, Wei

    2015-05-01

    The effects of ultrafine grinding on the dissolution rates of the effective components in Sanjie Zhentong capsule (SZC) were studied in this experiment. Fine and ultrafine powder of SZC intermediates were made by ordinary grinding and ultrafine grinding technology, and then granulated by wet granulation. SZC were prepared by fine powder, ultrafine powder and ultrafine granules, respectively. With resveratrol and loureirin B as investigated indexes, dissolution rates of the four intermediates in SZC were determined by cup method and HPLC. The dissolution rates of resveratrol in SZC prepared by fine powder, ultrafine powder and ultrafine granules were 26.11%, 63.27%, 67.49%, respectively; and the dissolution rates of loureirin B were 7.160%, 20.29%, 23.05%, respectively. The dissolution rate of resveratrol and loureirin B in SZC prepared by ultrafine granules was the best. D90 size of ultrafine grinding was 13.221 μm and could improve the dissolution rates of resveratrol and loureirin B in SZC. PMID:26390653

  4. A New Preparation Method of Ultrafine Particles of Metallic Sulfides

    NASA Astrophysics Data System (ADS)

    Kaito, Chihiro; Saito, Yoshio; Fujita, Kazuo

    1987-12-01

    Ultrafine particles of metallic sulfides have been produced by the reaction of metal and sulfur vapor. The sulfur vapor was prepared by evaporating sulfur powder from a quartz boat using the atmospheric temperature of either the heated metal or boat. Electron microscopic observation of the particles of Mo3S4 and PbS has shown them to be typical examples of the produced sulfides.

  5. OBSERVATION OF ULTRAFINE CHANNELS OF SOLAR CORONA HEATING

    SciTech Connect

    Ji, Haisheng; Cao, Wenda; Goode, Philip R.

    2012-05-01

    We report the first direct observations of dynamical events originating in the Sun's photosphere and subsequently lighting up the corona. Continuous small-scale, impulsive events have been tracked from their origin in the photosphere on through to their brightening of the local corona. We achieve this by combining high-resolution ground-based data from the 1.6 m aperture New Solar Telescope (NST) at Big Bear Solar Observatory (BBSO), and satellite data from the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The NST imaging observations in helium I 10830 A reveal unexpected complexes of ultrafine, hot magnetic loops seen to be reaching from the photosphere to the base of the corona. Most of these ultrafine loops are characterized by an apparently constant, but surprisingly narrow diameter of about 100 km all along each loop, and the loops originate on the solar surface from intense, compact magnetic field elements. The NST observations detect the signature of upward injections of hot plasma that excite the ultrafine loops from the photosphere to the base of the corona. The ejecta have their individual footpoints in the intergranular lanes between the Sun's ubiquitous, convectively driven granules. In many cases, AIA/SDO detects cospatial and cotemporal brightenings in the overlying, million degree coronal loops in conjunction with the upward injections along the ultrafine loops. Segments of some of the more intense upward injections are seen as rapid blueshifted events in simultaneous H{alpha} blue wing images observed at BBSO. In sum, the observations unambiguously show impulsive coronal heating events from upward energy flows originating from intergranular lanes on the solar surface accompanied by cospatial mass flows.

  6. Traffic emission factors of ultrafine particles: effects from ambient air.

    PubMed

    Janhäll, Sara; Molnar, Peter; Hallquist, Mattias

    2012-09-01

    Ultrafine particles have a significant detrimental effect on both human health and climate. In order to abate this problem, it is necessary to identify the sources of ultrafine particles. A parameterisation method is presented for estimating the levels of traffic-emitted ultrafine particles in terms of variables describing the ambient conditions. The method is versatile and could easily be applied to similar datasets in other environments. The data used were collected during a four-week period in February 2005, in Gothenburg, as part of the Göte-2005 campaign. The specific variables tested were temperature (T), relative humidity (RH), carbon monoxide concentration (CO), and the concentration of particles up to 10 μm diameter (PM(10)); all indicators are of importance for aerosol processes such as coagulation and gas-particle partitioning. These variables were selected because of their direct effect on aerosol processes (T and RH) or as proxies for aerosol surface area (CO and PM(10)) and because of their availability in local monitoring programmes, increasing the usability of the parameterization. Emission factors are presented for 10-100 nm particles (ultrafine particles; EF(ufp)), for 10-40 nm particles (EF(10-40)), and for 40-100 nm particles (EF(40-100)). For EF(40-100) no effect of ambient conditions was found. The emission factor equations are calculated based on an emission factor for NO(x) of 1 g km(-1), thus the particle emission factors are easily expressed in units of particles per gram of NO(x) emitted. For 10-100 nm particles the emission factor is EF(ufp) = 1.8 × 10(15) × (1 - 0.095 × CO - 3.2 × 10(-3) × T) particles km(-1). Alternative equations for the EFs in terms of T and PM(10) concentration are also presented. PMID:22858604

  7. Structural properties of ultrafine Ba-hexaferrite nanoparticles

    SciTech Connect

    Makovec, Darko; Primc, Darinka; Sturm, Saso; Kodre, Alojz; Jozef Stefan Institute, Jamova ulica 39, SI-1000 Ljubljana ; Hanzel, Darko; Drofenik, Miha; Jozef Stefan Institute, Jamova ulica 39, SI-1000 Ljubljana

    2012-12-15

    Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was studied using X-ray diffractometry (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDXS), X-ray absorption fine structure (XAFS), and Moessbauer spectroscopy (MS), to be compared to the structure of larger nanoparticles and the bulk. The nanoparticles were synthesized with hydrothermal treatment of an appropriate suspension of Ba and Fe hydroxides in the presence of a large excess of OH{sup -}. The ultrafine nanoparticles were formed in a discoid shape, {approx}10 nm wide and only {approx}3 nm thick, comparable to the size of the hexagonal unit cell in the c-direction. The HRTEM image analysis confirmed the hexaferrite structure, whereas EDXS showed the composition matching the BaFe{sub 12}O{sub 19} formula. XAFS and MS analyses showed considerable disorder of the structure, most probably responsible for the low magnetization. - Graphical abstract: Left: HREM image of an ultrafine Ba-hexaferrite nanoparticle (inset: TEM image of the nanoparticles); Right: the experimental HRTEM image is compared with calculated image and corresponding atomic model. Highlights: Black-Right-Pointing-Pointer Crystal structure of ultrafine Ba-hexaferrite (BaFe{sub 12}O{sub 19}) nanoparticles was compared to the structure of the bulk. Black-Right-Pointing-Pointer Thickness the discoid nanoparticles was comparable to the size of the hexagonal unit cell in the c-direction. Black-Right-Pointing-Pointer Considerable disorder of the nanoparticles' structure is most probably responsible for their low magnetization.

  8. Study of fine and ultrafine particles for coal cleaning

    SciTech Connect

    Birlingmair, D.; Buttermore, W.; Chmielewski, T.; Pollard, J.

    1990-04-01

    During the second quarter of work on this new project, critical review of the literature continued. Several new references related to gravity separation were identified and evaluated. A synopsis was assembled to summarize techniques developed by various researchers for the float/sink separation of ultrafine coal. In the reviewed literature, it was commonly concluded that substantial improvements in washability results for ultrafine coals can be obtained only through the application of dynamic (centrifugal) procedures, and through the use of dispersing aids such as ultrasound and surfactants. These results suggest the presence of physicochemical phenomena, typical of colloidal systems. In theoretical studies this quarter, the effects of Brownian motion on fine particle sedimentation have been identified and theoretically quantitated. The interaction between Brownian and gravitational forces was calculated, and a model was prepared to permit estimation of critical particle size in float/sink separations. In laboratory studies this quarter, aliquots of Upper Freeport coal were prepared and subjected to laboratory float/sink separations to investigate the relative effectiveness of static and centrifugal techniques for fine and ultrafine coal. This series will verify results of earlier work and provide a basis for comparing the effects which may result from further modifications to the separation techniques resulting from insights gained in the basic phenomena governing float/sink processes. 15 refs., 6 figs., 1 tab.

  9. Spectrophotometric determination of L-cysteine by using polyvinylpyrrolidone-stabilized silver nanoparticles in the presence of barium ions.

    PubMed

    Bamdad, Farzad; Khorram, Fateme; Samet, Maryam; Bamdad, Kourosh; Sangi, Mohammad Reza; Allahbakhshi, Fateme

    2016-05-15

    In this article a simple and selective colorimetric probe for cysteine determination using silver nano particles (AgNPS) is described. The determination process was based upon the surface plasmon resonance properties of polyvinylpyrrolidone-stabilized AgNPS. Interaction of AgNPS with cysteine molecules in the presence of barium ions induced a red shift in the surface plasmon resonance (SPR) maximum of AgNPs, as a result of nanoparticle aggregation. Consequently, yellow color of AgNP solution was changed to pink. The linear range for the determination of cysteine was 3.2-8.2 μM (R=0.9965) with a limit of detection equal to 2.8 μM (3σ). The proposed method was successfully applied to the determination of cysteine in human plasma samples. Acceptable recovery results of the spiked samples confirmed the validity of the proposed method. PMID:26950501

  10. Selective hydrogenation of m-chloronitrobenzene to m-chloroaniline over polyvinylpyrrolidone-stabilized Pt and Pt/Sn catalysts

    NASA Astrophysics Data System (ADS)

    Li, Feng; Ma, Rui; Song, Hualin; Song, Hua; Yu, Dezhi

    2015-05-01

    A Pt-polyvinylpyrrolidone (PVP) catalyst was synthesized via chemical reduction of platinum ions with hydrazine hydrate in a PVP/ n-butanol/H2PtCl6 aqueous solution. Its catalytic activity was evaluated by the liquid-phase hydrogenation of m-chloronitrobenzene ( m-CNB) to m-chloroaniline ( m-CAN) under mild conditions ( T = 303 K, p = 0.1 MPa). The as prepared catalyst exhibited higher activity and selectivity than prepared via conventional ethanol reduction with the same platinum load. The catalytic performance of PVP-Pt catalyst was remarkably improved by addition of 0.2 wt % Sn4+. The modification mechanism may be related with the interaction of Sn4+ with nitro group of m-CNB and -NH2 in m-CAN.

  11. Spectrophotometric determination of L-cysteine by using polyvinylpyrrolidone-stabilized silver nanoparticles in the presence of barium ions

    NASA Astrophysics Data System (ADS)

    Bamdad, Farzad; Khorram, Fateme; Samet, Maryam; Bamdad, Kourosh; Sangi, Mohammad Reza; Allahbakhshi, Fateme

    2016-05-01

    In this article a simple and selective colorimetric probe for cysteine determination using silver nano particles (AgNPS) is described. The determination process was based upon the surface plasmon resonance properties of polyvinylpyrrolidone-stabilized AgNPS. Interaction of AgNPS with cysteine molecules in the presence of barium ions induced a red shift in the surface plasmon resonance (SPR) maximum of AgNPs, as a result of nanoparticle aggregation. Consequently, yellow color of AgNP solution was changed to pink. The linear range for the determination of cysteine was 3.2-8.2 μM (R = 0.9965) with a limit of detection equal to 2.8 μM (3σ). The proposed method was successfully applied to the determination of cysteine in human plasma samples. Acceptable recovery results of the spiked samples confirmed the validity of the proposed method.

  12. Synthesis, characterization and Monte Carlo simulation of CoFe2O4/Polyvinylpyrrolidone nanocomposites: The coercivity investigation

    NASA Astrophysics Data System (ADS)

    Mirzaee, Sh; Farjami shayesteh, S.; Mahdavifar, S.; Hekmatara, S. Hoda.

    2015-11-01

    To study the influence of polymer matrix on the effective magnetic anisotropy constant and coercivity of magnetic nanoparticles, we have synthesized the Cobalt ferrite/Polyvinylpyrrolidone (PVP) nanocomposites by co-precipitation method in four different processes. In addition the Monte Carlo simulation and law of approach to the saturation magnetization have been applied to achieve the anisotropy constants. The obtained experimental and theoretical results showed a decrease in anisotropy constant relative to the bulk cobalt ferrite. We have showed that the PVP matrix can interact with metal cations and made them approximately immobilized to participate in spinel structure. Hence different anisotropy constants or coercivity were obtained for synthesized nanocomposites. In addition, PVP matrix can attach to the surface of magnetic particles and make them approximately non-interacting. The synthesized samples have been characterized by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Magnetic measurements were made at room temperature using a vibrating sample magnetometer (VSM).

  13. Polyvinylpyrrolidone-Poly(ethylene glycol) Modified Silver Nanorods Can Be a Safe, Noncarrier Adjuvant for HIV Vaccine.

    PubMed

    Liu, Ye; Balachandran, Yekkuni L; Li, Dan; Shao, Yiming; Jiang, Xingyu

    2016-03-22

    One of the biggest obstacles for the development of HIV vaccines is how to sufficiently trigger crucial anti-HIV immunities via a safe manner. We herein integrated surface modification-dependent immunostimulation against HIV vaccine and shape-dependent biosafety and designed a safe noncarrier adjuvant based on silver nanorods coated by both polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG). Such silver nanorods can significantly elevate crucial immunities of HIV vaccine and overcome the toxicity, which is a big problem for other existing adjuvants. This study thus provided a principle for designing a safe and high-efficacy material for an adjuvant and allow researchers to really have a safe and effective prophylaxis against HIV. We expect this material approach to be applicable to other types of vaccines, whether they are preventative or therapeutic. PMID:26844372

  14. Improvement of albendazole efficacy against enteral, but not against parenteral stages of Trichinella spiralis by preparing solid dispersions in polyvinylpyrrolidone.

    PubMed

    Lopez, M L; Torrado, S; Torrado, S; Martínez, A R; Bolás, F

    1997-01-01

    A comparison was made, in the Trichinella/mouse model, of the anthelmintic effects of albendazole (ABZ) and ricobendazole (RBZ) formulated as solid dispersions in polyvinylpyrrolidone with regard to ABZ formulated as a suspension in carboxymethylcellulose. A solid dispersion significantly increased (p < 0.01) the efficacy of the drugs against intestinal preadult but not against migrating and muscle stages of the parasite. The anthelmintic efficacy of RBZ given as a solid dispersion was equivalent to (against preadult and encysted larvae) or significantly lower than (against migrating larvae) that of ABZ with the same formulation. The pharmacokinetic profiles of ABZSO as measured by HPLC showed no significant differences in the Cmax and AUC following administration of ABZ formulated as a suspension or solid dispersion although the Tmax was significantly lower for the dispersion. PMID:9395857

  15. Measurement of clay surface areas by polyvinylpyrrolidone (PVP) sorption and its use for quantifying illite and smectite abundance

    USGS Publications Warehouse

    Blum, A.E.; Eberl, D.D.

    2004-01-01

    A new method has been developed for quantifying smectite abundance by sorbing polyvinylpyrrolidone (PVP) on smectite particles dispersed in aqueous solution. The sorption density of PVP-55K on a wide range of smectites, illites and kaolinites is ???0.99 mg/m2, which corresponds to ???0.72 g of PVP-55K per gram of montmorillonite. Polyvinylpyrrolidone sorption on smectites is independent of layer charge and solution pH. PVP sorption on Si02, Fe 2O3 and ZnO normalized to the BET surface area is similar to the sorption densities on smectites. ??-Al 2O3, amorphous Al(OH)3 and gibbsite have no PVP sorption over a wide range of pH, and sorption of PVP by organics is minimal. The insensitivity of PVP sorption densities to mineral layer charge, solution pH and mineral surface charge indicates that PVP sorption is not localized at charged sites, but is controlled by more broadly distributed sorption mechanisms such as Van der Waals' interactions and/or hydrogen bonding. Smectites have very large surface areas when dispersed as single unit-cell-thick particles (???725 m2/g) and usually dominate the total surface areas of natural samples in which smectites are present. In this case, smectite abundance is directly proportional to PVP sorption. In some cases, however, the accurate quantification of smectite abundance by PVP sorption may require minor corrections for PVP uptake by other phases, principally illite and kaolinite. Quantitative XRD can be combined with PVP uptake measurements to uniquely determine the smectite concentration in such sample. ?? 2004, The Clay Minerals Society.

  16. Effects of pyrolysis conditions on dielectric properties of PLZT films derived from a polyvinylpyrrolidone-modified sol-gel process

    SciTech Connect

    Chao, Sheng; Ma, Beihai; Liu, Shanshan; Narayanan, Manoj; Balachandran, Uthamalingam

    2012-03-15

    Graphical abstract: SEM images showing the surface morphology of PLZT films derived from solutions with various PVP content and treated with either RTA (rapid thermal annealing) or SPT (step-wise preheat treatment) process. Highlights: Black-Right-Pointing-Pointer High-quality PLZT films were fabricated by using a polyvinylpyrrolidone-modified sol-gel method. Black-Right-Pointing-Pointer Improved film density and integrity was achieved by employing a novel step-wise preheat treatment (SPT) process. Black-Right-Pointing-Pointer Enhanced dielectric properties were correlated to the improved microstructures as a result of the SPT process. -- Abstract: Pb{sub 0.92}La{sub 0.08}Zr{sub 0.52}Ti{sub 0.48}O{sub 3} (PLZT) films were deposited on platinized silicon substrates (Pt/Si) using a polyvinylpyrrolidone (PVP) modified sol-gel method. Pyrolysis of the green films was conducted via two methods: rapid thermal annealing (RTA) and a step-wise preheat treatment (SPT). Microstructure analysis and dielectric property characterization were performed on samples treated by these two methods. Results showed that the SPT-pyrolyzed films exhibited much better dielectric properties when compared with the RTA-pyrolyzed films. The differences in dielectric properties were correlated to microstructural features caused by the different pyrolysis conditions. High-quality PLZT films with high dielectric constant ( Almost-Equal-To 860 at zero bias) and high breakdown strength ( Almost-Equal-To 2.1 MV/cm) were fabricated under controlled pyrolysis conditions. This work demonstrated the potential application of this material for power electronics in electric drive vehicles.

  17. Evaluation of the of antibacterial efficacy of polyvinylpyrrolidone (PVP) and tri-sodium citrate (TSC) silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Dey, Arindam; Dasgupta, Abhirup; Kumar, Vijay; Tyagi, Aakriti; Verma, Anita Kamra

    2015-09-01

    We present silver nanoparticles as the new age broad spectrum antibiotic. Siver nanoparticles exhibit unique physical and chemical properties that make them suitable for understanding their biological potential as antimicrobials. In this study, we explored the antibacterial activity of silver nanoparticles (TSC-AgNPs) and silver nanoparticles doped with polyvinylpyrrolidone (PVP-AgNPs) against Gram-negative and Gram-positive bacteria, Escherichia coli (DH5α) and Staphylococcus aureus, (ATCC 13709). Nucleation and growth kinetics during the synthesis process of AgNPs were precisely controlled using citrate (TSC) and further doped with polyvinylpyrrolidone (PVP). This resulted in the formation of two different sized nanoparticles 34 and 54 nm with PDI of 0.426 and 0.643. The physical characterization was done by nanoparticle tracking analysis and scanning electron microscopy, the results of which are in unison with the digital light scattering data. We found the bactericidal effect for both TSC-AgNPs and PVP-AgNPs to be dose-dependent as determined by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against E. coli and S. aureus. Interestingly, we also observed that AgNPs showed enhanced antimicrobial activity with a MIC of 26.75 and 13.48 µg/ml for E. coli and S. aureus, respectively, while MBC for AgNPs are 53.23 and 26.75 µg/ml for E. coli and S. aureus, respectively. Moreover, AgNPs showed increased DNA degradation as observed confirming its higher efficacy as antibacterial agent than the PVP doped AgNPs.

  18. Dietary Fiber

    MedlinePlus

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble fiber or insoluble fiber. Both types have important health benefits. Good sources of dietary fiber include Whole grains Nuts ...

  19. Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions

    SciTech Connect

    Not Available

    1992-01-01

    The purpose of this program is to design and fabricate an experimental ultra-fine particle generation system; use this system to generate ultra-fine, iron compound, catalyst particles; and to access the ability of these ultra-fine catalyst particles to improve the performance of solubilization stage of two-stage, catalytic-catalytic liquefaction processes.

  20. Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions

    SciTech Connect

    Not Available

    1991-10-01

    The purpose of this program is to design and fabricate an experimental ultra-fine particle generation system; use this system to generate ultra-fine, iron compound, catalyst particles; and to access the ability of these ultra-fine catalyst particles to improve the performance of the solubilization stage of two-stage, catalytic-catalytic liquefaction processes.

  1. Annealing Characteristics of Ultrafine Grained Low-Carbon Steel Processed by Differential Speed Rolling Method

    NASA Astrophysics Data System (ADS)

    Hamad, Kotiba; Ko, Young Gun

    2016-05-01

    The annealing behavior of ultrafine grained ferrite in low-carbon steel (0.18 wt pct C) fabricated using a differential speed rolling (DSR) process was examined by observing the microstructural changes by electron backscatter diffraction and transmission electron microscopy. For this purpose, the samples processed by 4-pass DSR at a roll speed ratio of 1:4 for the lower and upper rolls, respectively, were annealed isochronally at temperatures ranging from 698 K to 898 K (425 °C to 625 °C) for 1 hour. The deformed samples exhibited a complex microstructure in the ferrite phase consisting of an equiaxed structure with a mean grain size of ~0.4 µm and a lamellar structure with a mean lamellar width of ~0.35 µm. The texture evolved during deformation was characterized by the rolling and shear components with specific orientations. After annealing at temperatures lower than 798 K (525 °C), the aspect ratio of the deformed grains tended to shift toward a unit corresponding to the equiaxed shape, whereas the grain size remained unchanged as the annealing temperature increased. At temperatures above 798 K (525 °C), however, some grains with a low dislocation density began to appear, suggesting that the starting temperature of static recrystallization in the severely deformed ferrite grains was 798 K (525 °C). The annealing texture of the present sample after heat treatment showed a uniform fiber texture consisting of α- and γ-components.

  2. Hydrogen Embrittlement of a 1500-MPa Tensile Strength Level Steel with an Ultrafine Elongated Grain Structure

    NASA Astrophysics Data System (ADS)

    Nie, Yihong; Kimura, Yuuji; Inoue, Tadanobu; Yin, Fuxing; Akiyama, Eiji; Tsuzaki, Kaneaki

    2012-05-01

    A deformation of a tempered martensitic structure ( i.e., tempforming) at 773 K (500 °C) was applied to a 0.6 pct C-2 pct Si-1 pct Cr steel. The hydrogen embrittlement (HE) property of the tempformed (TF) steel was investigated by a slow strain rate test (SSRT) and an accelerated atmospheric corrosion test (AACT). Hydrogen content within the samples after SSRT and AACT was measured by thermal desorption spectrometry (TDS). The tempforming at 773 K (500 °C) using multipass caliber rolling with an accumulative are reduction of 76 pct resulted in the evolution of an ultrafine elongated grain (UFEG) structure with a strong <110>//rolling direction (RD) fiber deformation texture and a dispersion of spheroidized cementite particles. The SSRT of the pre-hydrogen-charged notched specimens and the AACT demonstrated that the TF sample had superior potential for HE resistance to the conventional quenched and tempered (QT) sample at a tensile strength of 1500 MPa. The TDS analysis also indicated that the hydrogen might be mainly trapped by reversible trapping sites such as grain boundaries and dislocations in the TF sample, and the hydrogen trapping states of the TF sample were similar to those of the QT sample. The QT sample exhibited hydrogen-induced intergranular fracture along the boundaries of coarse prior-austenite grains. In contrast, the hydrogen-induced cracking occurred in association with the UFEG structure in the TF sample, leading to the higher HE resistance of the TF sample.

  3. Concentrations of ultrafine particles at a highway toll collection booth and exposure implications for toll collectors.

    PubMed

    Cheng, Yu-Hsiang; Huang, Cheng-Hsiung; Huang, Hsiao-Lin; Tsai, Chuen-Jinn

    2010-12-15

    Research regarding the magnitude of ultrafine particle levels at highway toll stations is limited. This study measured ambient concentrations of ultrafine particles at a highway toll station from October 30 to November 1 and November 5 to November 6, 2008. A scanning mobility particle sizer was used to measure ultrafine particle concentrations at a ticket/cash tollbooth. Levels of hourly average ultrafine particles at the tollbooth were about 3-6 times higher than those in urban backgrounds, indicating that a considerable amount of ultrafine particles are exhausted from passing vehicles. A bi-modal size distribution pattern with a dominant mode at about <6 nm and a minor mode at about 40 nm was observed at the tollbooth. The high amounts of nanoparticles in this study can be attributed to gas-to-particle reactions in fresh fumes emitted directly from vehicles. The influences of traffic volume, wind speed, and relative humidity on ultrafine particle concentrations were also determined. High ambient concentrations of ultrafine particles existed under low wind speed, low relative humidity, and high traffic volume. Although different factors account for high ambient concentrations of ultrafine particles at the tollbooth, measurements indicate that toll collectors who work close to traffic emission sources have a high exposure risk. PMID:21071066

  4. The persistence, transport and health effects of regional ultrafine particles

    NASA Astrophysics Data System (ADS)

    Spada, Nicholas James

    Due to the multitude of health studies that have shown the ability of ultrafine particles (UFPs, DP < 100 nm) to penetrate deep into lung tissue, diffuse into the bloodstream, and eventually cause heart and lung disease, my thesis will focus on these effectively unmonitored airborne pollutants. UFPs are commonly detected near busy roadways and other high-temperature combustion sources in the form of heavy metals (copper, lead, zinc, iron) and toxic organics (benzo{a}pyrene, coronene). Studies of UFPs during the 1970s expressed a nucleic propensity for coagulation and growth. Because many of the UFPs studied were generated from heavy-duty diesel engines operating with ≥0.3 wt % sulfur, the resulting sulfur-containing UFPs were hydrophilic and water vapor readily condensed on the generated nuclei. Due to their increased size, UFPs tend to settle out of air streams quickly; thus, limiting their impact regime to near-roadway influence and labeling them as local pollutants. By using highly size- and time-resolved impactors with TeflonRTM ultrafine after-filters (targeting DP < 90 nm), new evidence suggests the persistence of UFPs for greater periods of time and transport than previously predicted. Techniques developed during the Roseville rail yard study, refined during the Watt Ave/Arden Way study and applied across California's central valley have shown low levels of UFPs in a regional background. For cities in constrictive topography and meteorology (such as Bakersfield, Fresno and Los Angeles), winter inversions and stagnant weather can saturate the region with ultrafine heavy metals and carcinogenic organics, similar to the disasters during the middle of the last century.

  5. Comparison Between Different Processing Schedules for the Development of Ultrafine-Grained Dual-Phase Steel

    NASA Astrophysics Data System (ADS)

    Karmakar, Anish; Sivaprasad, S.; Nath, S. K.; Misra, R. D. K.; Chakrabarti, Debalay

    2014-05-01

    A comparative study was carried out on the development of ultrafine-grained dual-phase (DP) (ferrite-martensite) structures in a low-carbon microalloyed steel processed using two thermomechanical processing routes, (i) intercritical deformation and (ii) warm-deformation and intercritical annealing. The samples were deformed using Gleeble3500® simulator, maintaining a constant total strain ( ɛ = 1) and strain rate ( = 1/s). Evolution of microstructure and micro-texture was investigated by SEM, TEM, and EBSD. Ultrafine-grained DP structures could be formed by careful selection of deformation temperature, T def (for intercritical deformation) or annealing temperature, T anneal (for warm-deformation and annealing). Overall, the ferrite grain sizes ranged from 1.5 to 4.0 μm, and the sizes and fractions of the uniformly distributed fine-martensitic islands ranged from 1.5 to 3.0 μm and 15 to 45 pct, respectively. Dynamic strain-induced austenite-to-ferrite transformation followed by continuous (dynamic) recrystallization of the ferrite dictated the grain refinement during intercritical deformation, while, continuous (static) recrystallization by pronounced recovery dictated the grain refinement during the warm-deformation and the annealing. Regarding intercritical deformation, the samples cooled to T def indicated finer grain size compared with the samples heated to T def, which are explained in terms of the effects of strain partitioning on the ferrite and the heating during deformation. Alpha-fiber components dominated the texture in all the samples, and the fraction of high-angle boundaries (with >15 deg misorientation) increased with the increasing T def or T anneal, depending on the processing schedule. Fine carbide particles, microalloyed precipitates and austenitic islands played important roles in defining the mechanism of grain refinement that involved retarding conventional ferrite recrystallization and ferrite grain growth. With regard to the intercritical

  6. Ultrafine Metal-Organic Right Square Prism Shaped Nanowires.

    PubMed

    Otake, Ken-Ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-05-23

    We report the structural design and control of electronic states of a new series of ultrafine metal-organic right square prism-shaped nanowires. These nanowires have a very small inner diameter of about 2.0 Å, which is larger than hydrogen and similar to xenon atomic diameters. The electronic states of nanowires can be widely controlled by substitution of structural components. Moreover, the platinum homometallic nanowire shows a 100 times higher proton conductivity than a palladium/platinum heterometallic one depending on the electronic states. PMID:27080935

  7. Stabilization of ultrafine metal nanocatalysts on thin carbon sheets

    NASA Astrophysics Data System (ADS)

    Liu, Xiaofang; Cui, Xinrui; Liu, Yiding; Yin, Yadong

    2015-10-01

    A novel strategy was proposed to anchor ultrafine metal nanoparticles (NPs) on thin carbon sheets for highly stable and efficient heterogeneous catalysts. In this facile approach, a dense monolayer of ultrafine AuNPs was sandwiched between a silica core and a resin shell, followed by carbonization of the shell at a high temperature and then selective removal of the silica core. The shrinkage of the shells during carbonization facilitates partial embedment of the AuNPs on the carbon shell surface and provides superior stability against particle sintering during high temperature/mechanical post-treatments and catalytic reactions. It was also found that diffusion of reactants to the surface of AuNPs could be maximized by reducing the thickness of the hollow shells or simply by cracking the shells into thin carbon sheets, both significantly benefiting the catalytic efficiency. The advantages of this ultra-stable architecture together with the densely dispersed catalytic sites were demonstrated by their high stability and superior catalytic activity in reducing hydrophilic 4-nitrophenol and hydrophobic nitrobenzene.A novel strategy was proposed to anchor ultrafine metal nanoparticles (NPs) on thin carbon sheets for highly stable and efficient heterogeneous catalysts. In this facile approach, a dense monolayer of ultrafine AuNPs was sandwiched between a silica core and a resin shell, followed by carbonization of the shell at a high temperature and then selective removal of the silica core. The shrinkage of the shells during carbonization facilitates partial embedment of the AuNPs on the carbon shell surface and provides superior stability against particle sintering during high temperature/mechanical post-treatments and catalytic reactions. It was also found that diffusion of reactants to the surface of AuNPs could be maximized by reducing the thickness of the hollow shells or simply by cracking the shells into thin carbon sheets, both significantly benefiting the

  8. Calibration of TSI model 3025 ultrafine condensation particle counter

    SciTech Connect

    Kesten, J.; Reineking, A.; Porstendoerfer, J. )

    1991-01-01

    The registration efficiency of the TSI model 3025 ultrafine condensation particle counter for Ag and NaCl particles of between 2 and 20 nm in diameter was determined. Taking into account the different shapes of the input aerosol size distributions entering the differential mobility analyzer (DMA) and the transfer function of the DMA, the counting efficiencies of condensation nucleus counters (CNC) for monodisperse Ag and NaCl particles were estimated. In addition, the dependence of the CNC registration efficiency on the particle concentration was investigated.

  9. Method for the production of ultrafine particles by electrohydrodynamic micromixing

    DOEpatents

    DePaoli, David W.; Hu, Zhong Cheng; Tsouris, Constantinos

    2001-01-01

    The present invention relates to a method for the rapid production of homogeneous, ultrafine inorganic material via liquid-phase reactions. The method of the present invention employs electrohydrodynamic flows in the vicinity of an electrified injector tube placed inside another tube to induce efficient turbulent mixing of two fluids containing reactive species. The rapid micromixing allows liquid-phase reactions to be conducted uniformly at high rates. This approach allows continuous production of non-agglomerated, monopispersed, submicron-sized, sphere-like powders.

  10. Plasma synthesis and characterization of ultrafine SiC

    SciTech Connect

    Vogt, G.J.; Phillips, D.S.; Taylor, T.N.

    1986-01-01

    Ultrafine SiC powders have been prepared by gas phase synthesis from silane and methane in an argon thermal rf-plasma. Bulk properties of the powders were determined by elemental analysis, x-ray diffractin, helium pycnometry, and BET surface area measurements. The near-surface composition and structure of the particles were examined by x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). In addition to free silicon and carbon particles in the powders, free carbon and various silicon/carbon/oxygen species were found on the surface of the SiC particles.

  11. Process for making ultra-fine ceramic particles

    DOEpatents

    Stangle, Gregory C.; Venkatachari, Koththavasal R.; Ostrander, Steven P.; Schulze, Walter A.

    1995-01-01

    A process for producing ultra-fine ceramic particles in which droplets are formed from a ceramic precursor mixture containing a metal cation, a nitrogen-containing fuel, a solvent, and an anion capable of participating in an anionic oxidation-reduction reaction with the nitrogen containing fuel. The nitrogen-containing fuel contains at least three nitrogen atoms, at least one oxygen atom, and at least one carbon atom. The ceramic precursor mixture is dried to remove at least 85 weight percent of the solvent, and the dried mixture is then ignited to form a combusted powder.

  12. Electrodeposition of Indium Bumps for Ultrafine Pitch Interconnection

    NASA Astrophysics Data System (ADS)

    Tian, Yingtao; Liu, Changqing; Hutt, David; Stevens, Bob

    2014-02-01

    Electroplating is a promising method to produce ultrafine pitch indium bumps for assembly of pixel detectors in imaging applications. In this work, the process of indium bumping through electrodeposition was demonstrated and the influences of various current waveforms on the bump morphology, microstructure and height uniformity were investigated. Electron microscopy was used to study the microstructure of electroplated indium bumps and a Zygo white light interferometer was utilised to evaluate the height uniformity. The results indicated that the bump uniformities on wafer, pattern and feature scales were improved by using unipolar pulse and bipolar pulse reverse current waveforms.

  13. Fiber biology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cotton fiber cells arising from seed epidermis is the most important agricultural textile commodity in the world. To produce fully mature fibers, approximately two months of fiber developmental process are required. The timing of four distinctive fiber development stages consisting of initiation, ...

  14. Fine and ultrafine particle emissions from microwave popcorn.

    PubMed

    Zhang, Q; Avalos, J; Zhu, Y

    2014-04-01

    This study characterized fine (PM2.5 ) and ultrafine particle (UFP, diameter < 100 nm) emissions from microwave popcorn and analyzed influential factors. Each pre-packed popcorn bag was cooked in a microwave oven enclosed in a stainless steel chamber for 3 min. The number concentration and size distribution of UFPs and PM2.5 mass concentration were measured inside the chamber repeatedly for five different flavors under four increasing power settings using either the foil-lined original package or a brown paper bag. UFPs and PM2.5 generated by microwaving popcorn were 150-560 and 350-800 times higher than the emissions from microwaving water, respectively. About 90% of the total particles emitted were in the ultrafine size range. The emitted PM concentrations varied significantly with flavor. Replacing the foil-lined original package with a brown paper bag significantly reduced the peak concentration by 24-87% for total particle number and 36-70% for PM2.5 . A positive relationship was observed between both UFP number and PM2.5 mass and power setting. The emission rates of microwave popcorn ranged from 1.9 × 10(10) to 8.0 × 10(10) No./min for total particle number and from 134 to 249 μg/min for PM2.5 . PMID:24106981

  15. Exposure visualisation of ultrafine particle counts in a transport microenvironment

    NASA Astrophysics Data System (ADS)

    Kaur, S.; Clark, R. D. R.; Walsh, P. T.; Arnold, S. J.; Colvile, R. N.; Nieuwenhuijsen, M. J.

    An increasing number of studies indicate that short-term peak exposures, such as those seen in the transport microenvironment, pose particular health threats. Short-term exposure can only be sufficiently characterised using portable, fast-response monitoring instrumentation with detailed summaries of individual activity. In this paper, we present an exposure visualisation system that addresses this issue—it allows the simultaneous presentation of mobile video imagery synchronised with measured real-time ultrafine particle count exposure of an individual. The combined data can be examined in detail for the contribution of the surrounding environment and the individual's activities to their peak and overall exposure. The exposure visualisation system is demonstrated and evaluated around the DAPPLE study site in Central London using different modes of transport (walking, cycling, bus, car and taxi). The video images, synchronised with the exposure profile, highlight the extent to which ultrafine particle exposure is associated with traffic density and proximity to pollutant source. The extremely rapid decline in concentration with increasing distance away from the pollutant source, such as from the main street to the backstreets, is clearly evident. The visualisation technique allows these data to be presented to both technical audiences and laypersons thus making it an effective environmental risk communication tool. Some exposure peaks however are not obviously associated with any event recorded on video—in these cases it will be necessary to use advanced dispersion modelling techniques to investigate meteorological conditions and other variables influencing in-street conditions to identify their possible causes.

  16. Dissolution of populations of ultrafine grains with applications to feldspars

    NASA Astrophysics Data System (ADS)

    Talman, S. J.; Nesbitt, H. W.

    1988-06-01

    Mineral dissolution studies are difficult to interpret when the solid reactant displays a wide range in grain sizes, since the rate of dissolution of the finest grains may not be simply related to their surface area. The transient apparent rate of dissolution of a population of fine-grained reactants is modeled to predict changes to the solution composition, as well as changes in the size distribution of ultra-fine particles as functions of time. The model is applied to the experimental data on Amelia albite of HOLDREN and BERNER (1979) from which both solution composition and grain size distribution have been obtained. The observed size distribution cannot be duplicated if the dissolution rate is proportional to surface area ( i.e.dV/dt = Kr 2); other contributions to the rate, such as dependence on grain size and the specific contributions from edges and corners, must be invoked. The observed grain size distribution and pseudo-parabolic rate can be reproduced when the rate of dissolution of the fine grains is proportional to its radius ( i.e.dV/dt = kr ). The rate constant, k, is consistent with a rate limited by dissolution at the edges of the grains. The possibility of predicting both the contribution of ultra-fine particles to the observed dissolution rate and the time evolution of the grain size distribution makes the model a useful tool for interpreting mineral dissolution data.

  17. Ultrafine coal single stage dewatering and briquetting process

    SciTech Connect

    Wilson, J.W.; Ding, Y.; Tobey, M.

    1995-12-31

    The primary goal of the current physical coal cleaning process is to reduce the ash and sulfur content from the coal, that is, to remove the mineral particles from the coal. In order to separate mineral from coal particles efficiently, the finely disseminated mineral matter must be liberated from the coal matrix with the help of an ultrafine grinding operation. The coal becomes very difficult to dewater because of the small particle size produced. Difficulty in coal transportation as well as in its storage and handling at the utility plants are also problems associated with the small coal particles resulting from ultrafine grinding. During this project, several types of coal samples with various particle size distributions have been tested for use in the dewatering and briquetting processes. Furthermore, various bitumen emulsions have been tested to determine the optimum dewatering reagent. These dewatering and pelletizing tests were carried out using a lab-scale hydraulic compacting device. Discharge from the dewatering and briquetting processes was tested to determine compliance with current federal and state requirements. The influence of bitumen emulsion on the sulfur content of coal pellets made were also examined. In addition, a ram extruder which can be operated continuously to simulate a rotary press operation, has been built and is currently being tested for use in the fine coal dewatering and pelletizing process.

  18. Ultrafine coal single stage dewatering and briquetting process

    SciTech Connect

    Wilson, J.W.; Honaker, R.Q.

    1995-12-31

    It is well known that a large portion of the pyrite particles in the coal seams of the Illinois Basin are finely disseminated within the coal matrix. In order to liberate these micron size pyrite particles, one must use a fine grinding operation. The ultrafine coal particles are difficult to dewater and create problems in coal transportation, as well as in storage and handling at utility plants. The objective of this research project is to combine the ultrafine coal dewatering and briquetting processes into a single stage operation. This will be accomplished by the use of bitumen based emulsions for dewatering and a compaction device for briquetting. During this reporting period, several types of coal samples with various particle size distributions have been tested for use in the dewatering and briquetting processes. Furthermore, various bitumen emulsions have been tested to determine the optimum dewatering reagent. These dewatering and pelletizing tests were carried out using a lab-scale ram extruder. Discharge from the dewatering and briquetting processes was tested to determine compliance with current federal and state requirements. The influence of bitumen emulsion on the sulfur content of coal pellets made were also examined. In addition, a ram extruder which can be operated continuously to simulate a rotary press operation, has been built and is currently being tested for use in the fine coal dewatering and pelletizing process.

  19. Defect structure of ultrafine MgB{sub 2} nanoparticles

    SciTech Connect

    Bateni, Ali; Somer, Mehmet E-mail: msomer@ku.edu.tr; Repp, Sergej; Erdem, Emre E-mail: msomer@ku.edu.tr; Thomann, Ralf; Acar, Selçuk

    2014-11-17

    Defect structure of MgB{sub 2} bulk and ultrafine particles, synthesized by solid state reaction route, have been investigated mainly by the aid of X-band electron paramagnetic resonance spectrometer. Two different amorphous Boron (B) precursors were used for the synthesis of MgB{sub 2}, namely, boron 95 (purity 95%–97%, <1.5 μm) and nanoboron (purity >98.5%, <250 nm), which revealed bulk and nanosized MgB{sub 2}, respectively. Scanning and transmission electron microscopy analysis demonstrate uniform and ultrafine morphology for nanosized MgB{sub 2} in comparison with bulk MgB{sub 2}. Powder X-ray diffraction data show that the concentration of the by-product MgO is significantly reduced when nanoboron is employed as precursor. It is observed that a significant average particle size reduction for MgB{sub 2} can be achieved only by using B particles of micron or nano size. The origin and the role of defect centers were also investigated and the results proved that at nanoscale MgB{sub 2} material contains Mg vacancies. Such vacancies influence the connectivity and the conductivity properties which are crucial for the superconductivity applications.

  20. Process and apparatus for producing ultrafine explosive particles

    DOEpatents

    McGowan, Michael J.

    1992-10-20

    A method and an improved eductor apparatus for producing ultrafine explosive particles is disclosed. The explosive particles, which when incorporated into a binder system, have the ability to propagate in thin sheets, and have very low impact sensitivity and very high propagation sensitivity. A stream of a solution of the explosive dissolved in a solvent is thoroughly mixed with a stream of an inert nonsolvent by obtaining nonlaminar flow of the streams by applying pressure against the flow of the nonsolvent stream, to thereby diverge the stream as it contacts the explosive solution, and violently agitating the combined stream to rapidly precipitate the explosive particles from the solution in the form of generally spheroidal, ultrafine particles. The two streams are injected coaxially through continuous, concentric orifices of a nozzle into a mixing chamber. Preferably, the nonsolvent stream is injected centrally of the explosive solution stream. The explosive solution stream is injected downstream of and surrounds the nonsolvent solution stream for a substantial distance prior to being ejected into the mixing chamber.

  1. Deposition of ultrafine aerosols in rat nasal molds

    SciTech Connect

    Cheng, Y.S.; Hansen, G.K.; Su, Y.F.; Yeh, H.C. ); Morgan, K.T. )

    1990-01-01

    To evaluate the health effect of air pollutants on the respiratory tract, it is critical to determine the regional deposition of inhaled aerosols. Information on deposition of larger particles in the nasal passages of laboratory animals is available; the deposition fraction increases with increasing particle size. However, little deposition information is available for ultrafine particles of less than 0.2 {mu}m. Three clear, plastic molds (models) of the nasal passages of F344/N rats, prepared from metal replica casts used in these studies. Total deposition of ultrafine aerosols in the casts was determined by using a unidirectional flow system. The pressure drops measured in the casts were a function of flow rate to the power of 1.4-1.6, indicating that flow through the nasal passages has nonlaminar components. Deposition data were obtained by using monodisperse sodium chloride aerosols with particle sizes ranging from 0.2 to 0.005 {mu}m, at inspiratory and expiratory flow rates of 200 to 600 ml/min. Similar deposition data were obtained for two of the casts studied. Deposition efficiency was greatest for the smallest particles, and decreased with increasing particle size and flow rate. At an inspiratory flow rate of 400 ml/min, which is comparable to the mean respiratory flow of an adult male F344 rat with a respiratory minute volume of 200 ml, deposition efficiencies reached 40 and 70% for 0.01- and 0.005-{mu}m particles, respectively.

  2. Dynamics of ultrafine particles inside a roadway tunnel.

    PubMed

    Mishra, V K; Aggarwal, M L; Berghmans, P; Frijns, E; Int Panis, L; Chacko, K M

    2015-12-01

    Size-segregated ultrafine particles from motor vehicles were investigated in the Craeybeckx tunnel (E19 motorway, Antwerp, Belgium) at two measurement sites, at 100 and 300 m inside the tunnel, respectively, during March 2008. It was observed that out of the three size modes, nucleation, Aitken, and accumulation, Aitken mode was the most dominant size fraction inside the tunnel. The diurnal variation in ultrafine particle (UFP) levels closely follows the vehicular traffic inside the tunnel, which was maximum during office rush hours, both in the morning and evening and minimum during night-time around 3 am. The tunnel data showed very high growth rates in comparison with free atmosphere. The average condensation sink during the growth period was 14.1-17.3 × 10(-2) s(-1). The average growth rate (GR) of geometric mean diameter was found to be 18.6 ± 2.45 nm h(-1). It was observed that increase in Aitken mode was related to the numbers of heavy-duty vehicles (HDV), as they emit mainly in the Aitken mode. The higher Aitken mode during traffic jams correlated well with HDV numbers. At the end of the tunnel, sudden dilution leading to fast coagulation was responsible for the sudden drop in the UFP number concentration. PMID:26577216

  3. Experimental studies of ultrafine particles in streets and the relationship to traffic

    NASA Astrophysics Data System (ADS)

    Wahlina, Peter; Palmgren, Finn; Van Dingenen, Rita

    Fine and ultrafine particles are of great concern due to their adverse health effects. Furthermore, the emission of ultrafine particles has been reported to be increasing even if the total mass of particles emitted from vehicles decreases. Determination of emission factors of ultrafine particles from the actual car fleet for different types of vehicles is essential for reliable model calculations of the directly emitted particles from the traffic. The present study includes test of measurement methods and analysis of field data from Copenhagen. Measurements of fine and ultrafine particles were carried out during winter/spring 1999, at street level in central Copenhagen, at roof level in Copenhagen, and at street level in the city Odense. The measurements were carried out by differential mobility analyser (DMA) with a high-time resolution corresponding to the variation in traffic and meteorology. The particles were separated into 29 size fractions from 0.01 to 0.7 μm. Significant correlation at street level was observed between the CO, NO x, and ultrafine particles, indicating that the traffic is the major source of ultrafine particles in the air. Time series for several months of the size distributions have been analysed using statistical methods. Factor analysis has been used for the identification of the important sources, and a constrained linear receptor model has been used for source apportionment and for the determination of single-source size distributions of ultrafine particles from diesel- and petrol-fuelled vehicles.

  4. Flocculation, hydrophobic agglomeration and filtration of ultrafine coal

    NASA Astrophysics Data System (ADS)

    Yu, Zhimin

    In coal preparation plant circuits, fine coal particles are aggregated either by oil agglomeration or by flocculation. In a new hydrophobic agglomeration process, recently developed hydrophobic latices are utilized. While the selectivity of such aggregation processes determines the beneficiation results, the degree of aggregation has a strong effect on fine coal filtration. The aim of this research was to study the fundamentals and analyze the common grounds for these processes, including the potential effect of the coal surface properties. The selective flocculation tests, in which three types of coal, which differed widely in surface wettability, and three additives (hydrophobic latices, a semi-hydrophobic flocculant and a typical hydrophilic polyelectrolyte) were utilized, showed that coal wettability plays a very important role in selective flocculation. The abstraction of a hydrophobic latex on coal and silica revealed that the latex had a much higher affinity towards hydrophobic coal than to hydrophilic mineral matter. As a result, the UBC-1 hydrophobic latex flocculated only hydrophobic coal particles while the polyelectrolyte (PAM) flocculated all the tested coal samples and minerals, showing no selectivity in the fine coal beneficiation. The oil agglomeration was tested using kerosene emulsified with various surfactants (e.g. cationic, anionic and non-ionic). Surfactants enhance not only oil emulsification, hence reducing oil consumption (down to 0.25--0.5%), but also entirely change the electrokinetic properties of the droplets and affect the interaction energy between oil droplets and coal particles. Consequently, the results found in the course of the experimental work strongly indicate that even oxidized coals can be agglomerated if cationic surfactants are used to emulsify the oil. Oil agglomeration of the Ford-4 ultrafine coal showed that even at extremely low oil consumption (0.25 to 0.5%), a clean coal product with an ash content around 5% at over

  5. Dually enriched Cu:CdS@ZnS QDs with both polyvinylpyrrolidone twisting and SiO2 loading for improved cell imaging.

    PubMed

    Li, Mei; Xu, Chaoying; Wu, Lan; Wu, Peng; Hou, Xiandeng

    2015-02-28

    Through harvesting of the increased Stokes shift of CdS QDs via Cu-doping, the concentration-quenching or aggregation-quenching of CdS QDs was largely alleviated. A dually-enriched strategy with both polyvinylpyrrolidone (PVP) twisting and SiO2 loading was developed for generating a highly luminescent doped-dots (d-dots) assembly for improved cell imaging. PMID:25626901

  6. Effect of ultrafine grain on tensile behaviour and corrosion resistance of the duplex stainless steel.

    PubMed

    Jinlong, Lv; Tongxiang, Liang; Chen, Wang; Limin, Dong

    2016-05-01

    The ultrafine grained 2205 duplex stainless steel was obtained by cold rolling and annealing. The tensile properties were investigated at room temperature. Comparing with coarse grained stainless steel, ultrafine grained sample showed higher strength and plasticity. In addition, grain size changed deformation orientation. The strain induced α'-martensite was observed in coarse grained 2205 duplex stainless steel with large strain. However, the grain refinement inhibited the transformation of α'-martensite;nevertheless, more deformation twins improved the strength and plasticity of ultrafine grained 2205 duplex stainless steel. In addition, the grain refinement improved corrosion resistance of the 2205 duplex stainless steel in sodium chloride solution. PMID:26952459

  7. Labeling transplanted mice islet with polyvinylpyrrolidone coated superparamagnetic iron oxide nanoparticles for in vivo detection by magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Huang, Hai; Xie, Qiuping; Kang, Muxing; Zhang, Bo; Zhang, Hui; Chen, Jin; Zhai, Chuanxin; Yang, Deren; Jiang, Biao; Wu, Yulian

    2009-09-01

    Superparamagnetic iron oxide nanoparticles (SPIO) are emerging as a novel probe for noninvasive cell tracking with magnetic resonance imaging (MRI) and have potential wide usage in medical research. In this study, we have developed a method using high-temperature hydrolysis of chelate metal alkoxide complexes to synthesize polyvinylpyrrolidone coated iron oxide nanoparticles (PVP-SPIO), as a biocompatible magnetic agent that can efficiently label mice islet β-cells. The size, crystal structure and magnetic properties of the as-synthesized nanoparticles have been characterized. The newly synthesized PVP-SPIO with high stability, crystallinity and saturation magnetization can be efficiently internalized into β-cells, without affecting viability and function. The imaging of 100 PVP-SPIO-labeled mice islets in the syngeneic renal subcapsular model of transplantation under a clinical 3.0 T MR imager showed high spatial resolution in vivo. These results indicated the great potential application of the PVP-SPIO as an MRI contrast agent for monitoring transplanted islet grafts in the clinical management of diabetes in the near future.

  8. Influence of Sterilization and Storage Period on Elution of Polyvinylpyrrolidone from Wet-Type Polysulfone Membrane Dialyzers.

    PubMed

    Miyata, Masahiro; Konishi, Shuji; Shimamoto, Yoshimasa; Kamada, Aki; Umimoto, Koichi

    2015-01-01

    The objectives of this study were to investigate the influence of the sterilization and storage period on elution of polyvinylpyrrolidone (PVP) from wet-type polysulfone (PSu) membrane dialyzers. APS-15SA (APS) dialyzers sterilized by gamma-radiation and RENAK PS-1.6 (RENAK) dialyzers sterilized by autoclaving were compared in this study. Each dialyzer was washed with physiological saline and the amount of PVP eluted from the PSu membrane was measured. Then, experimental use of each dialyzer was performed by circulating physiological saline for 4 hours, after which the PVP eluted from the PSu membrane was measured. As the results, the amount of PVP eluted by washing was positively correlated with the storage period for both dialyzers (APS: rs = 0.958; RENAK: rs = 0.952). In the experimental circuit, the amount of PVP eluted from the RENAK dialyzer was positively correlated with the storage period (rs = 0.810), whereas the amount of PVP eluted from the APS dialyzer was negatively correlated with the storage period (rs = -0.833). We found that the amount of PVP eluted from PSu membrane is quite different by the sterilization and storage period of dialyzers. PMID:25851313

  9. Graphene/polyvinylpyrrolidone/polyaniline nanocomposite-modified electrode for simultaneous determination of parabens by high performance liquid chromatography.

    PubMed

    Kajornkavinkul, Suphunnee; Punrat, Eakkasit; Siangproh, Weena; Rodthongkum, Nadnudda; Praphairaksit, Narong; Chailapakul, Orawon

    2016-02-01

    A nanocomposite of graphene (G), polyvinylpyrrolidone (PVP) and polyaniline (PANI) modified onto screen-printed carbon electrode (SPCE) using an electrospraying technique was developed for simultaneous determination of five parabens in beverages and cosmetic products by high performance liquid chromatography. PVP and PANI were used as the dispersing agents of graphene, and also for the enhancement of electrochemical conductivity of the electrode. The electrochemical behavior of each paraben was investigated using the G/PVP/PANI nanocomposite-modified SPCE, compared to the unmodified SPCE. Using HPLC along with amperometric detection at a controlled potential of +1.2V vs Ag/AgCl, the chromatogram of five parabens obtained from the modified SPCE exhibits well defined peaks and higher current response than those of its unmodified counterpart. Under the optimal conditions, the calibration curves of five parabens similarly provide a linear range between 0.1 and 30 µg mL(-1) with the detection limits of 0.01 µg mL(-1) for methyl paraben (MP), ethyl paraben (EP) and propyl paraben (PP), 0.02 and 0.03 µg mL(-1) for isobutyl paraben (IBP) and butyl paraben (BP), respectively. Furthermore, this proposed method was applied for the simultaneous determination of five parabens in real samples including a soft drink and a cosmetic product with satisfactory results, yielding the recovery in the range of 90.4-105.0%. PMID:26653497

  10. Sensitive Adsorptive Voltammetric Method for Determination of Bisphenol A by Gold Nanoparticle/Polyvinylpyrrolidone-Modified Pencil Graphite Electrode.

    PubMed

    Yaman, Yesim Tugce; Abaci, Serdar

    2016-01-01

    A novel electrochemical sensor gold nanoparticle (AuNP)/polyvinylpyrrolidone (PVP) modified pencil graphite electrode (PGE) was developed for the ultrasensitive determination of Bisphenol A (BPA). The gold nanoparticles were electrodeposited by constant potential electrolysis and PVP was attached by passive adsorption onto the electrode surface. The electrode surfaces were characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The parameters that affected the experimental conditions were researched and optimized. The AuNP/PVP/PGE sensor provided high sensitivity and selectivity for BPA recognition by using square wave adsorptive stripping voltammetry (SWAdSV). Under optimized conditions, the detection limit was found to be 1.0 nM. This new sensor system offered the advantages of simple fabrication which aided the expeditious replication, low cost, fast response, high sensitivity and low background current for BPA. This new sensor system was successfully tested for the detection of the amount of BPA in bottled drinking water with high reliability. PMID:27231912

  11. 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

  12. Laser-assisted synthesis, and structural and thermal properties of ZnS nanoparticles stabilised in polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Onwudiwe, Damian C.; Krüger, Tjaart P. J.; Jordaan, Anine; Strydom, Christien A.

    2014-12-01

    Zinc sulphide (ZnS) nanoparticles have been synthesised by a green approach involving laser irradiation of an aqueous solution of zinc acetate (Znac2) and sodium sulphide (Na2S·9H2O) or thioacetamide (TAA) in polyvinylpyrrolidone (PVP). The structural and morphological properties of the prepared samples were analysed using a transmission electron microscope, TEM, a high resolution transmission electron microscope, HRTEM, X-ray diffraction, and Raman spectroscopy. The thermal properties were studied using a simultaneous thermal analyser (SDTA). Better dispersed and larger particles were obtained by using sodium sulphide (Na2S) instead of TAA as the sulphur source. X-ray diffraction (XRD) analyses and Raman measurement show that the particles have a cubic structure, which is usually a low temperature phase of ZnS. There were phonon softening and line broadening of the peaks which are attributed to the phonon confinement effect. The average crystallite size of the ZnS nanoparticles estimated from the XRD showed a reduction in size from 13.62 to 10.42 nm for samples obtained from Na2S, and 9.13 to 8.16 nm for samples obtained from TAA, with an increase in the time of irradiation. The thermal stability of PVP was increased due to the incorporation of the ZnS nanoparticles in the matrices. The absorption spectra showed that the nanoparticles exhibit quantum confinement effects.

  13. Novel polyvinylpyrrolidones to improve delivery of poorly water-soluble drugs: from design to synthesis and evaluation.

    PubMed

    Niemczyk, Anna I; Williams, Adrian C; Rawlinson-Malone, Clare F; Hayes, Wayne; Greenland, Barnaby W; Chappell, David; Khutoryanskaya, Olga; Timmins, Peter

    2012-08-01

    Polyvinylpyrrolidone is widely used in tablet formulations with the linear form acting as a wetting agent and disintegrant, whereas the cross-linked form is a superdisintegrant. We have previously reported that simply mixing the commercial cross-linked polymer with ibuprofen disrupted drug crystallinity with consequent improvements in drug dissolution behavior. In this study, we have designed and synthesized novel cross-linking agents containing a range of oligoether moieties that have then been polymerized with vinylpyrrolidone to generate a suite of novel excipients with enhanced hydrogen-bonding capabilities. The polymers have a porous surface and swell in the most common solvents and in water, properties that suggest their value as disintegrants. The polymers were evaluated in simple physical mixtures with ibuprofen as a model poorly water-soluble drug. The results show that the novel PVPs induce the drug to become "X-ray amorphous", which increased dissolution to a greater extent than that seen with commercial cross-linked PVP. The polymers stabilize the amorphous drug with no evidence for recrystallization seen after 20 weeks of storage. PMID:22738427

  14. High-Temperature Cross-Linking of Carbon Nanotube Multi-Yarn Using Polyvinylpyrrolidone as a Binding Agent.

    PubMed

    Misak, H; Asmatulu, R; Whitman, J; Mall, S

    2015-03-01

    Carbon nanotube (CNT) multi-yarn was cross-linked together at elevated temperatures using a poly- mer, with the intent of improving their strength and electrical conductivity. They were functionalized using an acid treatment and immersed in a bath of different concentrations (0.5%, 0.1%, and 0.2%) of polyvinylpyrrolidone (PVP). Then they were placed in an oven at various temperatures (180 °C, 200 °C, and 220 °C) in order to cause cross-linking among the carbon nanotube yarns. The phys- ical, chemical, electrical, and mechanical properties of the cross-linked yarns were investigated. The yarns cross-linked at higher temperatures and greater concentrations of PVP had a greater increase in linear mass density, indicating that the cross-linking process had worked as expected. Yarns that were cross-linked at lower temperatures had greater tensile strength and better spe- cific electrical conductivity. Those that were treated with a greater concentration of polymer had a greater ultimate tensile strength. All these results are encouraging first step, but still need further development if CNT yarn is to replace copper wire. PMID:26413653

  15. Humic substances alleviate the aquatic toxicity of polyvinylpyrrolidone-coated silver nanoparticles to organisms of different trophic levels.

    PubMed

    Wang, Zhuang; Quik, Joris T K; Song, Lan; Van Den Brandhof, Evert-Jan; Wouterse, Marja; Peijnenburg, Willie J G M

    2015-06-01

    The present study investigated how humic substances (HS) modify the aquatic toxicity of silver nanoparticles (AgNPs) as these particles agglomerate in water and interact with HS. An alga species (Raphidocelis subcapitata), a cladoceran species (Chydorus sphaericus), and a freshwater fish larva (Danio rerio), representing organisms of different trophic levels, were exposed to colloids of the polyvinylpyrrolidone-coated AgNPs in the presence and absence of HS. Results show that the presence of HS alleviated the aquatic toxicity of the AgNP colloids to all the organisms in a dose-dependent manner. The particle size distribution of the AgNPs' colloidal particles shifted to lower values due to the presence of HS, implying that the decrease in the toxicity of the AgNP colloids cannot be explained by the variation of agglomeration size. The surface charge of the AgNPs was found to be more negative in the presence of high concentrations of HS, suggesting an electrostatic barrier by which HS might limit interactions between particles and algae cells; indeed, this effect reduced the algae toxicity. Observations on silver ions (Ag(+)) release show that HS inhibit AgNP dissolution, depending on the concentrations of HS. When toxic effects were expressed as a function of each Ag-species, toxicity of the free Ag(+) was found to be much higher than that of the agglomerated particles. PMID:25683234

  16. Sensitive Adsorptive Voltammetric Method for Determination of Bisphenol A by Gold Nanoparticle/Polyvinylpyrrolidone-Modified Pencil Graphite Electrode

    PubMed Central

    Yaman, Yesim Tugce; Abaci, Serdar

    2016-01-01

    A novel electrochemical sensor gold nanoparticle (AuNP)/polyvinylpyrrolidone (PVP) modified pencil graphite electrode (PGE) was developed for the ultrasensitive determination of Bisphenol A (BPA). The gold nanoparticles were electrodeposited by constant potential electrolysis and PVP was attached by passive adsorption onto the electrode surface. The electrode surfaces were characterized by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). The parameters that affected the experimental conditions were researched and optimized. The AuNP/PVP/PGE sensor provided high sensitivity and selectivity for BPA recognition by using square wave adsorptive stripping voltammetry (SWAdSV). Under optimized conditions, the detection limit was found to be 1.0 nM. This new sensor system offered the advantages of simple fabrication which aided the expeditious replication, low cost, fast response, high sensitivity and low background current for BPA. This new sensor system was successfully tested for the detection of the amount of BPA in bottled drinking water with high reliability. PMID:27231912

  17. Structural Phase Transition Effect on Resistive Switching Behavior of MoS2 -Polyvinylpyrrolidone Nanocomposites Films for Flexible Memory Devices.

    PubMed

    Zhang, Peng; Gao, Cunxu; Xu, Benhua; Qi, Lin; Jiang, Changjun; Gao, Meizhen; Xue, Desheng

    2016-04-01

    The 2H phase and 1T phase coexisting in the same molybdenum disulfide (MoS2 ) nanosheets can influence the electronic properties of the materials. The 1T phase of MoS2 is introduced into the 2H-MoS2 nanosheets by two-step hydrothermal synthetic methods. Two types of nonvolatile memory effects, namely write-once read-many times memory and rewritable memory effect, are observed in the flexible memory devices with the configuration of Al/1T@2H-MoS2 -polyvinylpyrrolidone (PVP)/indium tin oxide (ITO)/polyethylene terephthalate (PET) and Al/2H-MoS2 -PVP/ITO/PET, respectively. It is observed that structural phase transition in MoS2 nanosheets plays an important role on the resistive switching behaviors of the MoS2 -based device. It is hoped that our results can offer a general route for the preparation of various promising nanocomposites based on 2D nanosheets of layered transition metal dichalcogenides for fabricating the high performance and flexible nonvolatile memory devices through regulating the phase structure in the 2D nanosheets. PMID:26938882

  18. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    NASA Astrophysics Data System (ADS)

    Zhang, Jinyu; Zhou, Guowei; Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d100), and cell parameter (a0) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d100 and a0 continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%.

  19. Evolution of structure and properties of granules containing microcrystalline cellulose and polyvinylpyrrolidone during high-shear wet granulation.

    PubMed

    Osei-Yeboah, Frederick; Feng, Yushi; Sun, Changquan Calvin

    2014-01-01

    Granulation behavior of microcrystalline cellulose (MCC) in the presence of 2.5% polyvinylpyrrolidone (PVP) was systematically studied. Complex changes in flowability and tabletability of lubricated MCC granules are correlated to changes in intragranular porosity, morphology, surface smoothness, size distribution, and specific surface area (SSA). With 2.5% PVP, the use of 45% granulation water leads to 84% reduction in tablet tensile strength and 76% improvement in powder flow factor. The changes in powder performance are explained by granule densification and surface smoothing. The granulating water level corresponding to the onset of overgranulation, 45%, is significantly lower than the 70% water required for unlubricated MCC granules without PVP. At more than 45% water levels, MCC-PVP granules flow well but cannot be compressed into intact tablets. Such changes in powder performance correspond to the rapid growth into large and dense spheres with smooth surface. Compared with MCC alone, the onset of the phase of fast granule size enlargement occurs at a lower water level when 2.5% PVP is used. Although the use of 2.5% PVP hastens granule nucleation and growth rate, the mechanisms of overgranulation are the same, that is, size enlargement, granule densification, surface smoothing, and particle rounding in both systems. PMID:24218097

  20. Cryomilling-induced solid dispersion of poor glass forming/poorly water-soluble mefenamic acid with polyvinylpyrrolidone K12.

    PubMed

    Kang, Naewon; Lee, Jangmi; Choi, Ji Na; Mao, Chen; Lee, Eun Hee

    2015-06-01

    The effect of mechanical impact on the polymorphic transformation of mefenamic acid (MFA) and the formation of a solid dispersion of mefenamic acid, a poor glass forming/poorly-water soluble compound, with polyvinylpyrrolidone (PVP) K12 was investigated. The implication of solid dispersion formation on solubility enhancement of MFA, prepared by cryomilling, was investigated. Solid state characterization was conducted using powder X-ray diffraction (PXRD) and Fourier-transform infrared (FTIR) spectroscopy combined with crystal structure analysis. Apparent solubility of the mixtures in pH 7.4 buffer was measured. A calculation to compare the powder patterns and FTIR spectra of solid dispersions with the corresponding physical mixtures was conducted. Solid state characterization showed that (1) MFA I transformed to MFA II when pure MFA I was cryogenically milled (CM); and (2) MFA forms a solid dispersion when MFA was cryogenically milled with PVP K12. FTIR spectral analysis showed that hydrogen bonding facilitated by mechanical impact played a major role in forming solid dispersions. The apparent solubility of MFA was significantly improved by making a solid dispersion with PVP K12 via cryomilling. This study highlights the importance of cryomilling with a good hydrogen bond forming excipient as a technique to prepare solid dispersion, especially when a compound shows a poor glass forming ability and therefore, is not easy to form amorphous forms by conventional method. PMID:24849785

  1. 5-Fluorouracil loaded Eudragit fibers prepared by electrospinning.

    PubMed

    Illangakoon, U Eranka; Yu, Deng-Guang; Ahmad, Bilal S; Chatterton, Nicholas P; Williams, Gareth R

    2015-11-30

    A series of 5-fluorouracil (5-FU) loaded core/shell electrospun fibers is reported. The fibers have shells made of Eudragit S100 (ES-100), and drug-loaded cores comprising poly(vinylpyrrolidone), ethyl cellulose, ES-100, or drug alone. Monolithic 5-FU loaded ES-100 fibers were also prepared for comparison. Electron microscopy showed all the fibers to have smooth cylindrical shapes, and clear core-shell structures were visible for all samples except the monolithic fibers. 5-FU was present in the amorphous physical form in all the materials prepared. Dissolution studies showed that the ES-100 shell was not able to prevent drug release at pH 1.0, even though the polymer is completely insoluble at this pH: around 30-80% of the maximum drug release was reached after 2h immersion at pH 1.0. These observations are ascribed to the low molecular weight of 5-FU permitting it to diffuse through pores in the ES-100 coating, and the relatively high acid solubility of the drug providing a thermodynamic impetus for this to happen. In addition, the fibers were observed to be broken or merged following 2h at pH 1.0, giving additional escape routes for the 5-FU. PMID:26410755

  2. SOURCE STRENGTHS OF ULTRAFINE AND FINE PARTICLES DUE TO COOKING WITH A GAS STOVE

    EPA Science Inventory

    Cooking, particularly frying, is an important source of particles indoors. Few studies have measured a full range of particle sizes, including ultrafine particles, produced during cooking. In this study, semicontinuous instruments with fine size discriminating ability were us...

  3. UPREGULATION OF TISSUE FACTOR IN HUMAN ENDOTHELIAL CELLS FOLLOWING ULTRAFINE PARTICLE EXPOSURE

    EPA Science Inventory

    Epidemiology studies have linked the exposure to air pollutant particles with increased cardiovascular mortality and morbidity, but the mechanisms remain unknown. In our laboratory we have tested the hypothesis that the ultrafine fraction of ambient pollutant particles would cau...

  4. Comparison of deposited surface area of airborne ultrafine particles generated from two welding processes.

    PubMed

    Gomes, J F; Albuquerque, P C; Miranda, Rosa M; Santos, Telmo G; Vieira, M T

    2012-09-01

    This article describes work performed on the assessment of the levels of airborne ultrafine particles emitted in two welding processes metal-active gas (MAG) of carbon steel and friction-stir welding (FSW) of aluminium in terms of deposited area in alveolar tract of the lung using a nanoparticle surface area monitor analyser. The obtained results showed the dependence from process parameters on emitted ultrafine particles and clearly demonstrated the presence of ultrafine particles, when compared with background levels. The obtained results showed that the process that results on the lower levels of alveolar-deposited surface area is FSW, unlike MAG. Nevertheless, all the tested processes resulted in important doses of ultrafine particles that are to be deposited in the human lung of exposed workers. PMID:22954401

  5. Vascular effects of ultrafine particles in persons with type 2 diabetes

    EPA Science Inventory

    BACKGROUND: Diabetes confers an increased risk for cardiovascular effects of airborne particles. OBJECTIVE: We hypothesized that inhalation of elemental carbon ultrafine particles (UFP) would activate blood platelets and vascular endothelium in people with type 2 diabetes. ...

  6. Cardiovascular Effects in Adults with Metabolic Syndrome Exposed to Concentrated Ultrafine Air Pollution Particles

    EPA Science Inventory

    RATIONALE: Epidemiologic studies report associations between ambient air pollution particulate matter (PM) and various indices of cardiopulmonary morbidity and mortality. A leading hypothesis contends that smaller ultrafine (UF) particles induce a greater physiologic response bec...

  7. Special Grain Boundaries in Ultrafine-Grained Tungsten

    NASA Astrophysics Data System (ADS)

    Dudka, O. V.; Ksenofontov, V. A.; Sadanov, E. V.; Starchenko, I. V.; Mazilova, T. I.; Mikhailovskij, I. M.

    2016-07-01

    Field ion microscopy and computer simulation were used for the study of an atomic structure high-angle grain boundary in hard-drawn ultrafine-grained tungsten wire. These boundaries with special misorientations are beyond the scope of the coincident site lattice model. It was demonstrated that the special non-coincident grain boundaries are the plane-matching boundaries, and rigid-body displacements of adjacent nanograins are normal to the <110> misorientation axis. The vectors of rigid-body translations of grains are described by broad asymmetric statistical distribution. Mathematical modeling showed that special incommensurate boundaries with one grain oriented along the {211} plane have comparatively high cohesive energies. The grain-boundary dislocations ½<110> were revealed and studied at the line of local mismatch of {110} atomic planes of adjacent grains.

  8. Special Grain Boundaries in Ultrafine-Grained Tungsten.

    PubMed

    Dudka, O V; Ksenofontov, V A; Sadanov, E V; Starchenko, I V; Mazilova, T I; Mikhailovskij, I M

    2016-12-01

    Field ion microscopy and computer simulation were used for the study of an atomic structure high-angle grain boundary in hard-drawn ultrafine-grained tungsten wire. These boundaries with special misorientations are beyond the scope of the coincident site lattice model. It was demonstrated that the special non-coincident grain boundaries are the plane-matching boundaries, and rigid-body displacements of adjacent nanograins are normal to the <110> misorientation axis. The vectors of rigid-body translations of grains are described by broad asymmetric statistical distribution. Mathematical modeling showed that special incommensurate boundaries with one grain oriented along the {211} plane have comparatively high cohesive energies. The grain-boundary dislocations ½<110> were revealed and studied at the line of local mismatch of {110} atomic planes of adjacent grains. PMID:27416905

  9. Acidic Ultrafine Tungsten Oxide Molecular Wires for Cellulosic Biomass Conversion.

    PubMed

    Zhang, Zhenxin; Sadakane, Masahiro; Hiyoshi, Norihito; Yoshida, Akihiro; Hara, Michikazu; Ueda, Wataru

    2016-08-22

    The application of nanocatalysis based on metal oxides for biomass conversion is of considerable interest in fundamental research and practical applications. New acidic transition-metal oxide molecular wires were synthesized for the conversion of cellulosic biomass. The ultrafine molecular wires were constructed by repeating (NH4 )2 [XW6 O21 ] (X=Te or Se) along the length, exhibiting diameters of only 1.2 nm. The nanowires dispersed in water and were observed using high-angle annular dark-field scanning transmission electron microscopy. Acid sites were created by calcination without collapse of the molecular wire structure. The acidic molecular wire exhibited high activity and stability and promoted the hydrolysis of the glycosidic bond. Various biomasses including cellulose were able to be converted to hexoses as main products. PMID:27482857

  10. Inelastic recovery in nano and ultrafine grained materials

    NASA Astrophysics Data System (ADS)

    Xie, Yuesong; Koslowski, Marisol

    2016-06-01

    Ultrafine and nano grained metals show plastic strain recovery upon unloading and reverse plastic strain during cyclic loading. It has been suggested that these phenomena are related to the residual stress due to grain size inhomogeneity and to grain boundary deformation mechanisms. Transmission electron microscopy (TEM) experiments indicate that dislocation structures also introduce inhomogeneous stress fields that can drive reverse plastic strain. We present dislocation dynamics simulations that show reverse plastic strain during cyclic loading even in microstructures with homogeneous grain size giving support to these TEM experiments. We also perform dislocation dynamics simulations coupled to a kinetic Monte Carlo algorithm to study thermally activated plastic strain recovery upon unloading. Our simulations show that these two plastic recovery processes are related to the formation of dislocation structures during loading, additionally grain size inhomogeneity increases the amount of plastic strain recovered.

  11. Air pollution, ultrafine and nanoparticle toxicology: cellular and molecular interactions.

    PubMed

    Stone, Vicki; Johnston, Helinor; Clift, Martin J D

    2007-12-01

    Nanotechnology is involved with the creation and/or manipulation of materials at the nanometer (nm) scale, and has arisen as a consequence of the novel properties that materials exhibit within the "nano" size range. The attraction of producing, and exploiting nanparticles (NPs; one dimension less than 100 nm) is a consequence of the fact that the properties are often strikingly different from bulk forms composed from the same material. As a consequence, the field of nanotechnology has generated substantial interest resulting in incorporation of NPs into a wide variety of products including electronics, food, clothing, medicines, cosmetics and sporting equipment. While there is general recognition that nanotechnology has the potential to advance science, quality of life and to generate substantial financial gains, a number of reports suggest that potential toxicity should be considered in order to allow the safe and sustainable development of such products. For example, substances which are ordinarily innocuous can elicit toxicity due to the altered chemical and physical properties that become evident within nano dimensions leading to potentially detrimental consequences for the producer, consumer or environment. Research into respirable air pollution particles (PM10) has focused on the role of ultrafine particle (diameter less than 100 nm) in inducing oxidative stress leading to inflammation and resulting in exacerbation of preexisting respiratory and cardiovascular disease. Epidemiological studies have repeatedly found a positive correlation between the level of particulate air pollution and increased morbidity and mortality rates in both adults and children. Such studies have also identified a link between respiratory ill health and the number of ambient ultrafine particles. In vivo and in vitro toxicology studies confirm that for low solubility, low toxicity materials such as TiO2, carbon black and polystyrene beads, ultrafine particles are more toxic and

  12. Lung response to ultrafine Kevlar aramid synthetic fibrils following 2-year inhalation exposure in rats.

    PubMed

    Lee, K P; Kelly, D P; O'Neal, F O; Stadler, J C; Kennedy, G L

    1988-07-01

    Four groups of 100 male and 100 female rats were exposed to ultrafine Kevlar fibrils at concentrations of 0, 2.5, 25, and 100 fibrils/cc for 6 hr/day, 5 days/week for 2 years. One group was exposed to 400 fibrils/cc for 1 year and allowed to recover for 1 year. At 2.5 fibrils/cc, the lungs had normal alveolar architecture with a few dust-laden macrophages (dust cell response) in the alveolar airspaces. At 25 fibrils/cc, the lungs showed a dust cell response, slight Type II pneumocyte hyperplasia, alveolar bronchiolarization, and a negligible amount of collagenized fibrosis in the alveolar duct region. At 100 fibrils/cc, the same pulmonary responses were seen as at 25 fibrils/cc. In addition, cystic keratinizing squamous cell carcinoma (CKSCC) was found in 4 female rats, but not in male rats. Female rats had more prominent foamy alveolar macrophages, cholesterol granulomas, and alveolar bronchiolarization. These pulmonary lesions were related to the development of CKSCC. The lung tumors were derived from metaplastic squamous cells in areas of alveolar bronchiolarization. At 400 fibrils/cc following 1 year of recovery, the lung dust content, average fiber length, and the pulmonary lesions were markedly reduced, but slight centriacinar emphysema and minimal collagenized fibrosis were found in the alveolar duct region. One male and 6 female rats developed CKSCC. The lung tumors were a unique type of experimentally induced tumors in the rats and have not been seen as spontaneous tumors in man or animals. Therefore, the relevance of this type of lung tumor to the human situation is minimal. PMID:3209007

  13. The characteristics of particle charging and deposition during powder coating processes with ultrafine powder

    NASA Astrophysics Data System (ADS)

    Meng, Xiangbo; Zhu, Jingxu Jesse; Zhang, Hui

    2009-03-01

    In a preceding work, the mechanisms of particle charging and deposition during powder coating processes were explored with coarse polyurethane powder. In this paper, the developed mechanisms were further examined with ultrafine polyurethane powder in order to meet the growing needs for ultrafine powder in finishing industries. This study first verified the previous findings in particle deposition, which account for a cone-shaped pattern formed by deposited particles on the substrate and a rise in particle accumulation in the fringe region. It was further demonstrated with ultrafine powder that, as disclosed by using coarse powder, the primary charging of in-flight particles competes with back corona in particle deposition processes, and the highest deposition efficiency is a compromise by balancing their effects. In comparison with coarse powder, ultrafine powder presents a faster reduction in the deposition rate with extended spraying duration, but shows some superiority in the uniformity of the deposited layer. In the case of charging characteristics of the deposited particles, it was further substantiated with ultrafine powder that the secondary charging mechanism takes predominance in determining the distribution of local charge-to-mass ratios. It was also disclosed that ultrafine powder shows a decreasing charge-to-mass ratio with increased charging voltage in the deposited layer, opposite to the increasing tendency of coarse powder. However, it was commonly demonstrated by both coarse and ultrafine powders that the charge-to-mass ratio of the deposited particles decreases with the extended spraying durations. In comparison, ultrafine powder is more likely to produce uniform charge-to-mass ratio distributions in the deposited layer, which contrast sharply with the ones associated with the coarse powder. In conclusion, it is believed that this study supplements the preceding study and is of great help in providing a comprehensive understanding of the mechanisms

  14. Decimeter Scale Ultra-Fine Fault Rocks (Possible Pseudotachylites) in an Ancient Subduction Thrust Zone

    NASA Astrophysics Data System (ADS)

    Rowe, C. D.; Moore, J. C.; Meneghini, F.; McKiernan, A. W.

    2004-12-01

    Large bodies of ultrafine fault rock (possible pseudotachylite or frictional melt) occur within cataclastic thrust zones in the Ghost Rocks Formation, Kodiak Accretionary Complex, Alaska. The Paleocene Ghost Rocks Formation includes map-scale mélange belts formed by flattening and shearing of seafloor sediments and volcanic rocks at about 250 degrees C and 325 MPa (~13 km depth) during subduction between 65-60Ma. Ten to 15-meter thick cataclastite zones crosscut the mélange fabric at a low angle, representing a stage of increasingly localized shear during subduction thrusting. Ultrafine fault rocks occur as thick (10-25cm) continuous planar beds along the boundaries of cataclastites, or in discontinuous accumulation bodies within cataclastite zones. The boundaries of the ultrafine fault rocks are intrusive, sharp but irregular and deform the cataclastite host fabric. Single pulse intrusions of the ultrafine fault rock range up to 0.5m in intrusive dimension and form complex morphologies resembling both upward and downward directed flame structures and dike-sill complexes, as well as sheath folds and disharmonic flow banding and folding. These field characteristics indicate fluidization and perhaps frictional melting of the ultrafine fault rocks. Ultrafine fault rock bodies can be traced laterally for meters to tens of meters at individual outcrops and occur for about 2 km along strike. Preliminary SEM analysis reveals that the primary matrix material is physically and chemically homogenous down to few-micron scale, consistent with the field identification of pseudotachylite. Thin sections show rounded remnant quartz aggregates, typical of pseudotachylytes. Although some thin sections show suggest melting others may represent ultracataclastite. Some ultrafine fault rock material is rebrecciated and cataclastized to a fine scale, indicating reactivation of previous fault rock generation surfaces. These ultrafine fault rock zones represent the most highly deformed

  15. Artificial ultra-fine aerosol tracers for highway transect studies

    NASA Astrophysics Data System (ADS)

    Cahill, Thomas A.; Barnes, David E.; Wuest, Leann; Gribble, David; Buscho, David; Miller, Roger S.; De la Croix, Camille

    2016-07-01

    The persistent evidence of health impacts of roadway aerosols requires extensive information for urban planning to avoid putting populations at risk, especially in-fill projects. The required information must cover both highway aerosol sources as well as transport into residential areas under a variety of roadway configurations, traffic conditions, downwind vegetation, and meteorology. Such studies are difficult and expensive to do, but were easier in the past when there was a robust fine aerosol tracer uniquely tied to traffic - lead. In this report we propose and test a modern alternative, highway safety flare aerosols. Roadway safety flares on vehicles in traffic can provide very fine and ultra-fine aerosols of unique composition that can be detected quantitatively far downwind of roadways due to a lack of upwind interferences. The collection method uses inexpensive portable aerosol collection hardware and x-ray analysis protocols. The time required for each transect is typically 1 h. Side by side tests showed precision at ± 4%. We have evaluated this technique both by aerosol removal in vegetation in a wind tunnel and by tracking aerosols downwind of freeways as a function of season, highway configuration and vegetation coverage. The results show that sound walls for at-grade freeways cause freeway pollution to extend much farther downwind than standard models predict. The elevated or fill section freeway on a berm projected essentially undiluted roadway aerosols at distances well beyond 325 m, deep into residential neighborhoods. Canopy vegetation with roughly 70% cover reduced very fine and ultra-fine aerosols by up to a factor of 2 at distances up to 200 m downwind.

  16. Ultrafine particle emissions from desktop 3D printers

    NASA Astrophysics Data System (ADS)

    Stephens, Brent; Azimi, Parham; El Orch, Zeineb; Ramos, Tiffanie

    2013-11-01

    The development of low-cost desktop versions of three-dimensional (3D) printers has made these devices widely accessible for rapid prototyping and small-scale manufacturing in home and office settings. Many desktop 3D printers rely on heated thermoplastic extrusion and deposition, which is a process that has been shown to have significant aerosol emissions in industrial environments. However, we are not aware of any data on particle emissions from commercially available desktop 3D printers. Therefore, we report on measurements of size-resolved and total ultrafine particle (UFP) concentrations resulting from the operation of two types of commercially available desktop 3D printers inside a commercial office space. We also estimate size-resolved (11.5 nm-116 nm) and total UFP (<100 nm) emission rates and compare them to emission rates from other desktop devices and indoor activities known to emit fine and ultrafine particles. Estimates of emission rates of total UFPs were large, ranging from ˜2.0 × 1010 # min-1 for a 3D printer utilizing a polylactic acid (PLA) feedstock to ˜1.9 × 1011 # min-1 for the same type of 3D printer utilizing a higher temperature acrylonitrile butadiene styrene (ABS) thermoplastic feedstock. Because most of these devices are currently sold as standalone devices without any exhaust ventilation or filtration accessories, results herein suggest caution should be used when operating in inadequately ventilated or unfiltered indoor environments. Additionally, these results suggest that more controlled experiments should be conducted to more fundamentally evaluate particle emissions from a wider arrange of desktop 3D printers.

  17. Ultrafine Particulate Ferrous Iron and Anthracene Associations with Mitochondrial Dysfunction

    SciTech Connect

    Faiola, Celia; Johansen, Anne M.; Rybka, Sara; Nieber, Annika; Thomas-Bradley, Carin; Bryner, Stephanie; Johnston, Justin M.; Engelhard, Mark H.; Nachimuthu, Ponnusamy; Owens, Kalyn S.

    2011-04-20

    The ultrafine size fraction of ambient particles (ultrafine particles, UFP, diameter < 100 nm) has been identified as being far more potent in their adverse health effects than their larger counterparts, yet, the detailed mechanisms for why UFP display such distinctive toxicity are not well understood. In the present study, ambient UFP were exposed to mitochondria while monitoring electron transport chain (ETC) activity as a model system for biochemical toxicity. UFP samples were collected in rural (Ellensburg, WA) and urban environments (Seattle, WA) and chemically characterized for total trace metals, ferrous (Fe(II)) and easily reducible ferric (Fe(III)) iron, polycyclic aromatic hydrocarbons, and surface constituents with X-ray photoelectron spectroscopy (XPS). Low doses of UFP (8 µg mL-1) caused a decrease in mitochondrial ETC function compared to controls in 94% of the samples after The 20 min of exposure. Significant correlations exist between initial %ETC inhibition (0-10 min) and Fe(II) (R=0.55, P=0.03, N=15), anthracene (R=0.74, P<0.01, N=13), and %C-O surface bonds (R=0.56, P=0.03, N=15), whereby anthracene and %C-O correlate as well (R=0.58, P=0.03, N=14). No significant associations were identified with total Fe and other trace metals. Results from this study indicate that the redox active fraction of Fe as well as the abundance of anthracene-related, C-O containing, surface structures may contribute to the initial detrimental behavior of UFP, thus supporting the idea that the Fe(II)/Fe(III) and certain efficient hydroquinone/quinone redox pairs may play an important role likely due to their potential to produce reactive oxygen species (ROS).

  18. Ultrafine grinding of low-rank coal: Final report

    SciTech Connect

    Bouchillon, C.W.; Steele, W.G.

    1986-08-01

    A study of ultrafine grinding of low-rank coals in a fluid-energy mill was undertaken. This report presents the results of the Phase I effort which included a review of the literature on ultrafine grinding, a review of theories of grinding, a combined grinding and drying experiment on Martin Lake Texas lignite, an evaluation of the energy requirements for the process, and an evaluation of the properties of the products from the grinding tests. A sample of Martin Lake Texas lignite was obtained and a series of tests were conducted in a fluid-energy mill at the Ergon, Inc., Micro-Energy Division development facility at Vicksburg, MS. The grinding fluids used were air at 116 F and steam at 225, 310, 350, 400, and 488 F as measured in the mill. The products of these tests were analyzed for volatile mattr, ash, total moisture, equilibrium moisture, heating value, density distribution, aerodynamic particle size classification, angle of repose, porosity, density, and particle size distribution. ASTM test procedures were followed where applicable. Ultimate and ash mineral analyses were also conducted on the samples. Results of the various tests are presented in detail in the report. In general, the fluid energy mill was used succssfully in simultaneous grinding and drying of the lignite. Particle size reduction to less than 10 microns on a population basis was achieved. The equilibrium moisture of the samples decreased with increasing grinding fluid temperatures. Density distribution studies showed that a significant fraction of the ash appeared in the >1.6 specific gravity particles. The energy required for the grinding/drying process increased with increasing mill temperatures. 29 refs., 18 figs., 13 tabs.

  19. Ultrafine particulate pollutants induce oxidative stress and mitochondrial damage.

    PubMed Central

    Li, Ning; Sioutas, Constantinos; Cho, Arthur; Schmitz, Debra; Misra, Chandan; Sempf, Joan; Wang, Meiying; Oberley, Terry; Froines, John; Nel, Andre

    2003-01-01

    The objectives of this study were to determine whether differences in the size and composition of coarse (2.5-10 micro m), fine (< 2.5 microm), and ultrafine (< 0.1 microm) particulate matter (PM) are related to their uptake in macrophages and epithelial cells and their ability to induce oxidative stress. The premise for this study is the increasing awareness that various PM components induce pulmonary inflammation through the generation of oxidative stress. Coarse, fine, and ultrafine particles (UFPs) were collected by ambient particle concentrators in the Los Angeles basin in California and used to study their chemical composition in parallel with assays for generation of reactive oxygen species (ROS) and ability to induce oxidative stress in macrophages and epithelial cells. UFPs were most potent toward inducing cellular heme oxygenase-1 (HO-1) expression and depleting intracellular glutathione. HO-1 expression, a sensitive marker for oxidative stress, is directly correlated with the high organic carbon and polycyclic aromatic hydrocarbon (PAH) content of UFPs. The dithiothreitol (DTT) assay, a quantitative measure of in vitro ROS formation, was correlated with PAH content and HO-1 expression. UFPs also had the highest ROS activity in the DTT assay. Because the small size of UFPs allows better tissue penetration, we used electron microscopy to study subcellular localization. UFPs and, to a lesser extent, fine particles, localize in mitochondria, where they induce major structural damage. This may contribute to oxidative stress. Our studies demonstrate that the increased biological potency of UFPs is related to the content of redox cycling organic chemicals and their ability to damage mitochondria. PMID:12676598

  20. [Distribution of atmospheric ultrafine particles during haze weather in Hangzhou].

    PubMed

    Chen, Qiu-Fang; Sun, Zai; Xie, Xiao-Fang

    2014-08-01

    Atmospheric ultrafine particles (UFPs) were monitored with fast mobility particle sizer (FMPS) in continuous haze weather and the haze fading process during December 6 to 11, 2013 in Hangzhou. Particle concentration and size distribution were studied associated with meteorological factors. The results showed that number concentrations were the highest at night and began to reduce in the morning. There was a small peak at 8 o'clock in the morning and 18 o'clock in the afternoon. It showed an obvious peak traffic source, which indicated that traffic emissions played a great role in the atmospheric pollution. During haze weather, the highest number concentration of UFPs reached 8 x 10(4) cm(-3). Particle size spectrum distribution was bimodal, the peak particle sizes were 15 nm and 100 nm respectively. Majority of UFPs were Aitken mode and Accumulation mode and the size of most particles concentrated near 100 nm. Average CMD(count medium diameter) was 85.89 nm. During haze fading process, number concentration and particles with size around 100 nm began to reduce and peak size shifted to small size. Nuclear modal particles increased and were more than accumulation mode. Average CMD was 58.64 nm. Meteorological factors such as the visibility and wind were negatively correlated with the particle number concentration. Correlation coefficient R were -0.225 and - 0.229. The humidity was correlated with number concentration. Correlation coefficient R was 0.271. The atmosphere was stable in winter and the level temperature had small correlation with number concentration. Therefore, study on distribution of atmospheric ultrafine particles during haze weather had the significance on the formation mechanism and control of haze weather. PMID:25338351

  1. Dietary Fiber

    MedlinePlus

    Fiber is a substance in plants. Dietary fiber is the kind you eat. It's a type of carbohydrate. You may also see it listed on a food label as soluble ... types have important health benefits. Good sources of dietary fiber include Whole grains Nuts and seeds Fruit and ...

  2. Large-scale and highly efficient synthesis of micro- and nano-fibers with controlled fiber morphology by centrifugal jet spinning for tissue regeneration

    NASA Astrophysics Data System (ADS)

    Ren, Liyun; Pandit, Vaibhav; Elkin, Joshua; Denman, Tyler; Cooper, James A.; Kotha, Shiva P.

    2013-02-01

    PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a highly efficient synthesis method for micron- to nano-sized fibers with a production rate up to 0.5 g min-1. During the centrifugal jet spinning process, a polymer solution jet is stretched by the centrifugal force of a rotating chamber. By engineering the rheological properties of the polymer solution, solvent evaporation rate and centrifugal force that are applied on the solution jet, polyvinylpyrrolidone (PVP) and poly(l-lactic acid) (PLLA) composite fibers with various diameters are fabricated. Viscosity measurements of polymer solutions allowed us to determine critical polymer chain entanglement limits that allow the generation of continuous fiber as opposed to beads or beaded fibers. Above a critical concentration at which polymer chains are partially or fully entangled, lower polymer concentrations and higher centrifugal forces resulted in thinner fibers. Etching of PVP from the PLLA-PVP composite fibers doped with increasing PVP concentrations yielded PLLA fibers with increasing nano-scale surface roughness and porosity, which increased the fiber hydrophilicity dramatically. Scanning electron micrographs of the etched composite fibers suggest that PVP and PLLA were co-contiguously phase separated within the composite fibers during spinning and nano-scale roughness features were created after the partial etching of PVP. To study the tissue regeneration efficacy of the engineered PLLA fiber matrix, human dermal fibroblasts are used to simulate partial skin graft. Fibers with increased PLLA surface roughness and porosity demonstrated a trend towards higher cell attachment and proliferation.PLLA fibrous tissue scaffolds with controlled fiber nanoscale surface roughness are fabricated with a novel centrifugal jet spinning process. The centrifugal jet spinning technique is a

  3. Emission of ultrafine particles from the incineration of municipal solid waste: A review

    NASA Astrophysics Data System (ADS)

    Jones, Alan M.; Harrison, Roy M.

    2016-09-01

    Ultrafine particles (diameter <100 nm) are of great topical interest because of concerns over possible enhanced toxicity relative to larger particles of the same composition. While combustion processes, and especially road traffic exhaust are a known major source of ultrafine particle emissions, relatively little is known of the magnitude of emissions from non-traffic sources. One such source is the incineration of municipal waste, and this article reviews studies carried out on the emissions from modern municipal waste incinerators. The effects of engineering controls upon particle emissions are considered, as well as the very limited information on the effects of changing waste composition. The results of measurements of incinerator flue gas, and of atmospheric sampling at ground level in the vicinity of incinerators, show that typical ultrafine particle concentrations in flue gas are broadly similar to those in urban air and that consequently, after the dispersion process dilutes incinerator exhaust with ambient air, ultrafine particle concentrations are typically indistinguishable from those that would occur in the absence of the incinerator. In some cases the ultrafine particle concentration in the flue gas may be below that in the local ambient air. This appears to be a consequence of the removal of semi-volatile vapours in the secondary combustion zone and abatement plant, and the high efficiency of fabric filters for ultrafine particle collection.

  4. Combined gene therapy of endostatin and interleukin 12 with polyvinylpyrrolidone induces a potent antitumor effect on hepatoma

    PubMed Central

    Li, Pei-Yuan; Lin, Ju-Sheng; Feng, Zuo-Hua; He, Yu-Fei; Zhou, He-Jun; Ma, Xin; Cai, Xiao-Kun; Tian, De-An

    2004-01-01

    AIM: To study the antitumor effect of combined gene therapy of endostatin and interleukin 12 (IL-12) with polyvinylpyrrolidone (PVP) on mouse transplanted hepatoma. METHODS: Mouse endostatin eukaryotic plasmid (pSecES) with a mouse Igκ signal sequence inside and mouse IL-12 eukaryotic plasmid (pmIL-12) were transfected into BHK-21 cells respectively. Endostatin and IL-12 were assayed by ELISA from the supernant and used to culture endothelial cells and spleen lymphocytes individually. Proliferation of the latter was evaluated by MTT. H22 cells were inoculated into the leg muscle of mouse, which was injected intratumorally with pSecES/PVP, pmIL-12/PVP or pSecES + pmIL-12/PVP repeatedly. Tumor weight, serum endostatin and serum IL-12 were assayed. Tumor infiltrating lymphocytes, tumor microvessel density and apoptosis of tumor cells were also displayed by HE staining, CD31 staining and TUNEL. RESULTS: Endostatin and IL-12 were secreted after transfection, which could inhibit the proliferation of endothelial cells or promote the proliferation of spleen lymphocytes. Tumor growth was highly inhibited by 91.8% after injection of pSecES + pmIL-12/PVP accompanied by higher serum endostatin and IL-12, more infiltrating lymphocytes, fewer tumor vessels and more apoptosis cells compared with injection of pSecES/PVP, pmIL-12/PVP or vector/PVP. CONCLUSION: Mouse endostatin gene and IL-12 gene can be expressed after intratumoral injection with PVP. Angiogenesis of hepatoma can be inhibited synergisticly, lymphocytes can be activated to infiltrate, and tumor cells are induced to apoptosis. Hepatoma can be highly inhibited or eradiated. PMID:15259064

  5. Controlling the Integration of Polyvinylpyrrolidone onto Substrate by Quartz Crystal Microbalance with Dissipation To Achieve Excellent Protein Resistance and Detoxification.

    PubMed

    Zheng, Jian; Wang, Lin; Zeng, Xiangze; Zheng, Xiaoyan; Zhang, Yan; Liu, Sa; Shi, Xuetao; Wang, Yingjun; Huang, Xuhui; Ren, Li

    2016-07-27

    Blood purification systems, in which the adsorbent removes exogenous and endogenous toxins from the blood, are widely used in clinical practice. To improve the protein resistance of and detoxification by the adsorbent, researchers can modify the adsorbent with functional molecules, such as polyvinylpyrrolidone (PVP). However, achieving precise control of the functional molecular density, which is crucial to the activity of the adsorbent, remains a significant challenge. In the present study, we prepared a model system for blood purification adsorbents in which we controlled the integration density of PVP molecules of different molecular weights on an Au substrate by quartz crystal microbalance with dissipation (QCM-D). We characterized the samples with atomic force microscopy, X-ray photoelectron spectroscopy, and QCM-D and found that the molecular density and the chain length of the PVP molecules played important roles in determining the properties of the sample. At the optimal condition, the modified sample demonstrated strong resistance to plasma proteins, decreasing the adsorption of human serum albumin (HSA) and fibrinogen (Fg) by 92.5% and 79.2%, respectively. In addition, the modified sample exhibited excellent detoxification, and the adsorption of bilirubin increased 2.6-fold. Interestingly, subsequent atomistic molecular dynamics simulations indicated that the favorable interactions between PVP and bilirubin were dominated by hydrophobic interactions. An in vitro platelet adhesion assay showed that the adhesion of platelets on the sample decreased and that the platelets were maintained in an inactivated state. The CCK-8 assay indicated that the modified sample exhibited negligible cytotoxicity to L929 cells. These results demonstrated that our method holds great potential for the modification of adsorbents in blood purification systems. PMID:27363467

  6. [Toxicological evaluation of colloidal nano-sized silver stabilized polyvinylpyrrolidone. III. Enzymological, biochemical markers, state of antioxidant defense system].

    PubMed

    Gmoshinsky, I V; Shipelin, V A; Vorozhko, I V; Sentsova, T B; Soto, S Kh; Avren'eva, L I; Guseva, G V; Kravchenko, L V; Khotimchenko, S A; Tutelyan, V A

    2016-01-01

    Nanosized colloidal silver (NCS) with primary nanoparticles (NPs) size in the range of 10-80 nm in aqueous suspension was administered to rats with initial weight 80±10 gfor the first 30 day intragastrically and for lasting 62 days with the diet consumed in doses of 0.1; 1.0 and 10 mg/kg of body weight b.w) per day based on silver (Ag). The control animals received deionized water and carrier of NPs - aqueous solution of stabilizer polyvinylpyrrolidone. Activity (Vmax) was determined in liver of microsomal mixed function monooxygenase isoforms CYP 1A1, 1A2 and 2B1 against their specific substrates, the activity of liver conjugating enzymes (glutathione-S-transferase and UDP-glucuronosyltransferase) in the microsomal fraction and a cytosol, and the overall and non-sedimentable activities of lysosomal hydrolases. In blood plasma there were evaluated malonic dialdehyde, PUFA diene conjugates, in erythrocytes - the activity of antioxidant enzymes. A set of standard biochemical indicators of blood serum was also determined. The studies revealed changes in a number of molecular markers of toxic action. Among them - the increase in the activity of key enzymes I and II stages of detoxification of xenobiotics, indicating its functional overvoltage; reducing the activity of glutathione peroxidase (GP), the total arylsulfatase A and B, β-galactosidase (in the absence of changes in their non-sedimentable activity), levels of uric acid, increased alkaline phosphatase activity. These changes occurred mainly at the dose Ag of 10 mg/kg b.w., except for the GP to which the threshold dose was 1 mg/kg b.w. No significant changes in the studied markers in a dose Ag 0,1 mg/kg b.w. were identified. Possible mechanisms of the toxic action of silver NPs are discussed. PMID:27455597

  7. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    SciTech Connect

    Zhang, Jinyu; Zhou, Guowei Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d{sub 100}), and cell parameter (a{sub 0}) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d{sub 100} and a{sub 0} continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%. - Graphical abstract: Curved rod-shaped mesoporous silica can be obtained at low and the highest PVP concentration, while straight rod-shaped mesoporous silica can be obtained at higher PVP concentration. - Highlights: • Mesoporous silica with morphology evolution from CRMS to SRMS were prepared. • Effects of PVP molecular weight and concentration on silica morphology were studied. • A possible mechanism for the formation of morphology evolution SiO{sub 2} was proposed. • Esterification of lauric acid with 1-butanol catalyzed by immobilized PPL.

  8. Preparation, molecular weight determination and structural studies of (polyvinylpyrrolidone)-oximate silico-benzoyl glycine copolymer with IR spectroscopy.

    PubMed

    Singh, Man; Chauhan, Sushila

    2007-05-01

    Polyvinylpyrrolidone (PVP)-oximate silico-benzoyl glycine (POSBG), a glycine copolymer, has been prepared with PVP-oxime and benzoyl glycine in 1 : 1 ratio, w/w, in ethanol medium.The ethanolic solution with silicic acid [Si(OH)4] as binder in same ratio was refluxed for 2-3 h resulting in a colloidal solution, which was further refluxed for 2 h and cooled to 37 degrees C for 15 min. After this a whitish solid material settled, which was separated by vacuum filtration followed by washing several times with aqueous ethanol at ordinary conditions. The average viscosity molecular weights Mv of PVP-oxime and the copolymer were determined with their respective dilute aqueous solutions. Primarily the calibration curves between the intrinsic viscosity (eta) data and their respective molecular weights of polyvinyl alcohol (PVOH) (marker)have been obtained to determine the Mv of oxime. Similarly the Mv of the copolymer was determined with the (eta) data of lysozyme (molecular weight=24,000 g mol(-1)), egg albumin(40,000 g mol (-1)) and BSA (65,000 g mol (-1)). The IR spectra of the PVP-oxime and copolymer were recorded in Nujol, which do not depict band frequency of -OH group of the binder. The 1602, 1688, 1182 and 1127 cm-1 stretching vibration frequencies noted in the spectra infer the presence of -C=N, -C=O, -Si-O-Si- and -Si-O-C- functional groups, respectively, in the copolymer. PMID:17487614

  9. One-dimensional multiferroic bismuth ferrite fibers obtained by electrospinning techniques.

    PubMed

    Baji, Avinash; Mai, Yiu-Wing; Li, Qian; Wong, Shing-Chung; Liu, Yun; Yao, Q W

    2011-06-10

    We report the fabrication of novel multiferroic nanostructured bismuth ferrite (BiFeO(3)) fibers using the sol-gel based electrospinning technique. Phase pure BiFeO(3) fibers were prepared by thermally annealing the electrospun BiFeO(3)/polyvinylpyrrolidone composite fibers in air for 1 h at 600 °C. The x-ray diffraction pattern of the fibers (BiFeO(3)) obtained showed that their crystalline structures were rhombohedral perovskite structures. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images revealed that the BiFeO(3) fibers were composed of fine grained microstructures. The grains were self-assembled and self-organized to yield dense and continuous fibrous structures. The magnetic hysteresis loops of these nanostructured fibers displayed the expected ferromagnetic behavior, whereby a coercivity of ∼ 250 Oe and a saturation magnetization of ∼ 1.34 emu g(-1) were obtained. The ferroelectricity and ferroelectric domain structures of the fibers were confirmed using piezoresponse force microscopy (PFM). The piezoelectric hysteresis loops and polar domain switching behavior of the fibers were examined. Such multiferroic fibers are significant for electroactive applications and nano-scale devices. PMID:21483046

  10. Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions

    SciTech Connect

    Not Available

    1991-09-01

    The purpose of this program is to design and fabricate an experimental ultra-fine particle generation system; use this system to generate ultra-fine, iron compound, catalyst particles; and to access the ability of these ultra-fine catalyst particles to improve the performance of the solubilization stage of two-stage, catalytic-catalytic liquefaction processes. The effort applied to this program during this reporting period was devoted to experimental design and fabrication tasks.

  11. Atmospheric pressure plasma assisted calcination of composite submicron fibers

    NASA Astrophysics Data System (ADS)

    Medvecká, Veronika; Kováčik, Dušan; Tučeková, Zlata; Zahoranová, Anna; Černák, Mirko

    2016-08-01

    The plasma assisted calcination of composite organic/inorganic submicron fibers for the preparation of inorganic fibers in submicron scale was studied. Aluminium butoxide/polyvinylpyrrolidone fibers prepared by electrospinning were treated using low-temperature plasma generated by special type of dielectric barrier discharge, so called diffuse coplanar surface barrier discharge (DCSBD) at atmospheric pressure in ambient air, synthetic air, oxygen and nitrogen. Effect of plasma treatment on base polymer removal was investigated by using Attenuated total reflectance - Fourier transform infrared (ATR-FTIR) spectroscopy. Influence of working gas on the base polymer reduction was studied by energy-dispersive X-ray spectroscopy (EDX) and CHNS elemental analysis. Changes in fibers morphology were observed by scanning electron microscopy (SEM). High efficiency of organic template removal without any degradation of fibers was observed after plasma treatment in ambient air. Due to the low-temperature approach and short exposure time, the plasma assisted calcination is a promising alternative to the conventional thermal calcination. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  12. Contribution of nitrated polycyclic aromatic hydrocarbons to the mutagenicity of ultrafine particles in the roadside atmosphere

    NASA Astrophysics Data System (ADS)

    Kawanaka, Youhei; Matsumoto, Emiko; Wang, Ning; Yun, Sun-Ja; Sakamoto, Kazuhiko

    This is the first report of the quantification of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in ultrafine particles in the roadside atmosphere and their contribution to the direct-acting mutagenicity of ultrafine particles. The detailed size distributions of six nitro-PAHs (2-nitrofluoranthene, 1-nitropyrene, 6-nitrobenzo[a]pyrene, 1,3-dinitropyrene, 1,6-dinitropyrene, and 1,8-dinitropyrene) were measured by highly sensitive gas chromatography-negative ion chemical ionization tandem mass spectrometry. Direct-acting mutagenicity of size-fractionated particulate matter (PM) was determined by the Ames test using Salmonella typhimurium strains TA98 and YG1024. The amounts of nitro-PAHs per unit mass of ultrafine particles (<0.12 μm) were significantly higher than those of accumulation mode particles (0.12-2.1 μm) and of coarse particles (>2.1 μm). Therefore, more than 20% of each nitro-PAH, with the exception of 2-nitrofluoranthene, was observed in the ultrafine particle fraction, although the contribution of ultrafine particles to the total PM mass in the roadside atmosphere was only 2.3%. Also, in both tester strains TA98 and YG1024, the mutagenicity per unit mass of ultrafine particles was significantly higher than those of accumulation mode particles or coarse particles. The contributions of 2-nitrofluoranthene, 1-nitropyrene, 1,3-dinitropyrene, 1,6-dinitropyrene, and 1,8-dinitropyrene to the direct-acting mutagenicity of ultrafine particles were 0.56, 1.5, 0.57, 2.2, and 9.2%, respectively, in the TA98 strain, and 0.54, 1.1, 0.71, 5.0, and 17%, respectively, in the YG1024 strain, while the contribution of 6-nitrobenzo[a]pyrene was less than 0.01% in both strains. 1,8-Dinitropyrene was the largest contributor to the mutagenicity not only of ultrafine particles but also of accumulation mode particles in both strains. Only five nitro-PAHs accounted for as much as 14 and 24% of the direct-acting mutagenicity of ultrafine particles in the roadside

  13. Electrospinning preparation and photoluminescence properties of erbium complex doped composite fibers

    NASA Astrophysics Data System (ADS)

    Cui, Xiao; Zhang, He Ming; Wu, Tie Feng

    2011-09-01

    In this paper, an Er(III) complex of Er(DBM) 3IPD, where DBM = 1,3-diphenyl-propane-1,3-dione and IPD = 4-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-N,N-diphenylaniline, is synthesized and doped into poly(vinylpyrrolidone) submicron fibers through electrospinning technique. The crystal structure and morphology are investigated in detail. The composite fibers exhibit smooth and uniform morphology on the substrate, with an average diameter of ˜1.4 μm. Photophysical data suggest that DBM ligand sensitizes Er(III) center efficiently and provides an optimal condition for radiative decay, and low temperature can enhance the emission intensity by suppressing the quenching effect. It is found that the photostability of Er(III) complex doped composite fibers is largely improved compared with that of pure complex.

  14. Separation of Water from Ultralow Sulfur Diesel Using Novel Polymer Nanofiber-Coated Glass Fiber Media.

    PubMed

    Rajgarhia, Stuti S; Jana, Sadhan C; Chase, George G

    2016-08-24

    Polymer nanofibers with interpenetrating network (IPN) morphology are used in this work for the development of composite, hydrophobic filter media in conjunction with glass fibers for removal of water droplets from ultralow sulfur diesel (ULSD). The nanofibers are produced from hydrophobic polyvinyl acetate (PVAc) and hydrophilic polyvinylpyrrolidone (PVP) by spinning the polymer solutions using gas jet fiber (GJF) method. The nanofibers coat the individual glass fibers due to polar-polar interactions during the spinning process and render the filter media highly hydrophobic with a water contact angle approaching 150°. The efficiency of the resultant filter media is evaluated in terms of separation of water droplets of average size 20 μm from the suspensions in ULSD. PMID:27486993

  15. Controllable synthesis and down-conversion properties of flower-like NaY(MoO{sub 4}){sub 2} microcrystals via polyvinylpyrrolidone-mediated

    SciTech Connect

    Lin, Han; Yan, Xiaohong; Wang, Xiangfu

    2013-08-15

    Double alkaline rare-earth molybdates NaY(MoO{sub 4}){sub 2} with multilayered flower-like architectures have been successfully synthesized via hydrothermal method in polyvinylpyrrolidone (PVP)-modified processes. The crystal structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that reaction time and the amount of PVP have crucial influences on the morphology of the resulting novel microstructures. Under 450 nm excitation, Ho{sup 3+}/Yb{sup 3+} co-doped NaY(MoO{sub 4}){sub 2} samples exhibit 539 nm green emission and 960–1200 nm broadband near-infrared emission, corresponding to the characteristic lines of Ho{sup 3+} and Yb{sup 3+}, respectively. Moreover, increasing Yb{sup 3+} doping enhances the energy transfer efficiency from Ho{sup 3+} to Yb{sup 3+}. - Graphical abstract: Low and high-magnification SEM images demonstrate the perfect flower-like NaY(MoO{sub 4}){sub 2} prepared in the presence of PVP; Detailed TEM and HRTEM images further manifest the single-crystalline feature. Highlights: • NaY(MoO{sub 4}){sub 2} flower-like microstructures were synthesized by hydrothermal method using polyvinylpyrrolidone. • Polyvinylpyrrolidone induces the growth of the NaY(MoO{sub 4}){sub 2} to form multilayered architectures. • Flowerlike NaY(MoO{sub 4}){sub 2}: Ho{sup 3+}, Yb{sup 3+} phosphors were investigated as a downconversion layer candidate.

  16. Fiber sensing with photorefractive fiber

    NASA Astrophysics Data System (ADS)

    Yu, Francis T. S.; Guo, Ruyan; Wang, Bo; Liu, Yuexin

    2002-11-01

    Optical fibers have been widely used for transmitting temporal signal. However, the transmission of spatial signal has not been fully exploited. Although multimode fiber has a large space-bandwidth product, transmitting spatial signals by using a fiber is rather difficult. When a laser beam is lached into a multimode fiber, the exit light field produces a complicated speckle pattern caused by the modal phasing of the fiber. It is difficult to recover the transmitted informati from the speckle field. However, the fiber speckle field can be used to fiber sensing with a hologrpahic method. In other words, if a hologram is made with the speckle fiber field, the information of the fiber status can be recovered. Thus by reading the hologram by the same speckle field, the reference beam can be reconstructed, which represents the detection of the speckle field. In other words, instead of exploiting the temporal content, the spatial content from a multimode fiber can be exploited for sensing. Our analyses and experimentations have shown that the fiber specklegram sensor (FSS) is highly senstiive to perturbation, and it is less vulnerable to the environment factors. Applications of the FSS to temperature, transversal displacement, and dynamic sensing are also included.

  17. 24-gauge ultrafine cryoprobe with diameter of 550 μm and its cooling performance.

    PubMed

    Okajima, Junnosuke; Komiya, Atsuki; Maruyama, Shigenao

    2014-12-01

    This paper describes the development of a novel cryoprobe with the same size as a 24-gauge injection needle and the evaluation of its cooling performance. This ultrafine cryoprobe was designed to reduce the invasiveness and extend application areas of cryosurgery. The ultrafine cryoprobe has a double-tube structure and consists of two stainless steel microtubes. The outer diameter of the cryoprobe is 550 μm, and the inner tube has a 70-μm inner diameter to depressurize the high-pressure refrigerant. By solving the bioheat transfer equation and considering freezing phenomena, the relationship between the size of the frozen region and the heat transfer coefficient of the refrigerant flow in an ultrafine cryoprobe was derived analytically. The results showed that the size of the frozen region is strongly affected by the heat transfer coefficient. A high heat transfer coefficient such as that of phase change heat transfer is required to generate a frozen region of sufficient size. In the experiment, trifluoromethane (HFC-23) was used as the refrigerant, and the cooling effects of the gas and liquid phase states at the inlet were evaluated. When the ultrafine cryoprobe was cooled using a liquid refrigerant, the surface temperature was approximately -50°C, and the temperature distribution on the surface was uniform for a thermally insulated condition. However, for the case with vaporized refrigerant, the temperature distribution was not uniform. Therefore, it was concluded that the cooling mechanism using liquid refrigerant was suitable for ultrafine cryoprobes. Furthermore, to simulate cryosurgery, a cooling experiment using hydrogel was conducted. The results showed that the surface temperature of the ultrafine cryoprobe reached -35°C and formed a frozen region with a radius of 4 mm in 4 min. These results indicate that the ultrafine cryoprobe can be applied in actual cryosurgeries for small affected areas. PMID:25305055

  18. Enhanced bone formation in electrospun poly(L-lactic-co-glycolic acid)-tussah silk fibroin ultrafine nanofiber scaffolds incorporated with graphene oxide.

    PubMed

    Shao, Weili; He, Jianxin; Sang, Feng; Wang, Qian; Chen, Li; Cui, Shizhong; Ding, Bin

    2016-05-01

    To engineer bone tissue, it is necessary to provide a biocompatible, mechanically robust scaffold. In this study, we fabricated an ultrafine nanofiber scaffold by electrospinning a blend of poly(L-lactic-co-glycolic acid), tussah silk fibroin, and graphene oxide (GO) and characterized its morphology, biocompatibility, mechanical properties, and biological activity. The data indicate that incorporation of 10 wt.% tussah silk and 1 wt.% graphene oxide into poly(L-lactic-co-glycolic acid) nanofibers significantly decreased the fiber diameter from 280 to 130 nm. Furthermore, tussah silk and graphene oxide boosted the Young's modulus and tensile strength by nearly 4-fold and 3-fold, respectively, and significantly enhanced adhesion, proliferation in mouse mesenchymal stem cells and functionally promoted biomineralization-relevant alkaline phosphatase (ALP) and mineral deposition. The results indicate that composite nanofibers could be excellent and versatile scaffolds for bone tissue engineering. PMID:26952489

  19. Coaxially electrospun fiber-based microbicides facilitate broadly tunable release of maraviroc.

    PubMed

    Ball, Cameron; Chou, Shih-Feng; Jiang, Yonghou; Woodrow, Kim A

    2016-06-01

    Electrospun fibers show potential as a topical delivery system for vaginal microbicides. Previous reports have demonstrated delivery of anti-HIV and anti-STI (sexually transmitted infection) agents from fibers formulated using hydrophilic, hydrophobic, or pH-responsive polymers that result in rapid, prolonged, or stimuli-responsive release, respectively. However, coaxial electrospun fibers have yet to be evaluated as a highly tunable microbicide delivery vehicle. In this research, we explored the opportunities and limitations of a model coaxial electrospun fiber system to provide broad and tunable release rates for the HIV entry inhibitor maraviroc. Specifically, we prepared ethyl cellulose (EC)-shell and polyvinylpyrrolidone (PVP)-core fibers that were capable of releasing actives over a range of hours to several days. We further demonstrated simple and effective methods for combining core-shell fibers with rapid-release formulations to provide combined instantaneous and sustained maraviroc release. In addition, we investigated the effect of varying release media on maraviroc release from core-shell fibers, and found that release was strongly influenced by media surface tension and drug ionization. Finally, in vitro cell culture studies show that our fiber formulations were not cytotoxic and that electrospun maraviroc maintained similar antiviral activity compared to neat maraviroc. PMID:27040202

  20. Assemblies of polyvinylpyrrolidone-capped tetrahedral and spherical Pt nanoparticles in polyelectrolytes: hydrogen underpotential deposition and electrochemical characterization.

    PubMed

    Jaber, Sarah; Nasr, Pamela; Xin, Yan; Sleem, Fatima; Halaoui, Lara I

    2013-09-28

    Polyvinylpyrrolidone (PVP)-capped Pt nanoparticles (NPs) were synthesized in mostly tetrahedral (TH-Pt, [edge] = 4.3 ± 0.7 nm) or spherical (S-Pt, [d] = 3.4 ± 0.8 nm) shapes and assembled layer-by-layer in poly(diallyldimethylammonium) chloride on electrodes driven by electrostatic and hydrophobic interactions. The nanostructured Pt electrodes were characterized using hydrogen underpotential deposition (H(upd)) in 1 M H2SO4. The H(upd) charge increased linearly with the PDDA-Pt NP adsorption cycle measured up to 10 cycles revealing a linear incorporation of Pt NPs per cycle, indicative of reproducible surface charge reversal despite the submonolayer NP coverage imaged by TEM on a PDDA layer, and showing the feasibility of charge and mass transport in the thickness of the films. H(upd) at both PVP-TH-Pt and PVP-S-Pt occurred in two states, a major weak-adsorption H(W) peak, and a minor strong-adsorption state H(S) appearing as a shoulder. H(upd) features and other electrochemical processes at assemblies of PVP-Pt NP in PDDA were compared to assemblies of 2.5 nm polyacrylate-capped Pt NPs in PDDA and to polycrystalline Pt. Results indicated that H(W) adsorption likely occurs on a PVP-modified Pt NP surface without being accompanied by PVP desorption, while H(S) occurs on free (100) sites. The PVP-Pt NPs were resistant to surface oxidation and were stable against usual surface restructuring when scanned into the Pt-oxide potential region as they remained modified with PVP. O2 evolution was also suppressed by PVP-capping compared to PAC-Pt NPs and polycryst-Pt, but the assemblies were electrocatalytic for hydrogen evolution, hydrogen oxidation, and oxygen reduction. Increasing anodic polarization increased the H(W) charge but without causing a potential shift, indicating absence of PVP decapping or Pt surface restructuring, but possibly some structural polymer rearrangement increasing the accessibility of buried sites for H-adsorption. PMID:23928658

  1. Exposure to Inhalable, Respirable, and Ultrafine Particles in Welding Fume

    PubMed Central

    Pesch, Beate

    2012-01-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m−3 for inhalable and 1.29 mg m−3 for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m−3). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements

  2. Microalloying ultrafine grained Al alloys with enhanced ductility.

    PubMed

    Jiang, L; Li, J K; Cheng, P M; Liu, G; Wang, R H; Chen, B A; Zhang, J Y; Sun, J; Yang, M X; Yang, G

    2014-01-01

    Bulk ultrafine grained (UFG)/nanocrystal metals possess exceptional strength but normally poor ductility and thermal stability, which hinder their practical applications especially in high-temperature environments. Through microalloying strategy that enables the control of grains and precipitations in nanostructured regime, here we design and successfully produce a highly microstructure-stable UFG Al-Cu-Sc alloy with ~275% increment in ductility and simultaneously ~50% enhancement in yield strength compared with its Sc-free counterpart. Although the precipitations in UFG alloys are usually preferentially occurred at grain boundaries even at room temperature, minor Sc addition into the UFG Al-Cu alloys is found to effectively stabilize the as-processed microstructure, strongly suppress the θ-Al2Cu phase precipitation at grain boundary, and remarkably promote the θ'-Al2Cu nanoparticles dispersed in the grain interior in artificial aging. A similar microalloying strategy is expected to be equally effective for other UFG heat-treatable alloys. PMID:24398915

  3. Personal Exposure to Ultrafine Particles and Oxidative DNA Damage

    PubMed Central

    Vinzents, Peter S.; Møller, Peter; Sørensen, Mette; Knudsen, Lisbeth E.; Hertel, Ole; Jensen, Finn Palmgren; Schibye, Bente; Loft, Steffen

    2005-01-01

    Exposure to ultrafine particles (UFPs) from vehicle exhaust has been related to risk of cardiovascular and pulmonary disease and cancer, even though exposure assessment is difficult. We studied personal exposure in terms of number concentrations of UFPs in the breathing zone, using portable instruments in six 18-hr periods in 15 healthy nonsmoking subjects. Exposure contrasts of outdoor pollution were achieved by bicycling in traffic for 5 days and in the laboratory for 1 day. Oxidative DNA damage was assessed as strand breaks and oxidized purines in mononuclear cells isolated from venous blood the morning after exposure measurement. Cumulated outdoor and cumulated indoor exposures to UFPs each were independent significant predictors of the level of purine oxidation in DNA but not of strand breaks. Ambient air concentrations of particulate matter with an aero-dynamic diameter of ≤10 μm (PM10), nitrous oxide, nitrogen dioxide, carbon monoxide, and/or number concentration of UFPs at urban background or busy street monitoring stations was not a significant predictor of DNA damage, although personal UFP exposure was correlated with urban background concentrations of CO and NO2, particularly during bicycling in traffic. The results indicate that biologic effects of UFPs occur at modest exposure, such as that occurring in traffic, which supports the relationship of UFPs and the adverse health effects of air pollution. PMID:16263500

  4. Ultrafine Nanoparticle-Supported Ru Nanoclusters with Ultrahigh Catalytic Activity.

    PubMed

    Zhu, Lihua; Jiang, Yingying; Zheng, Jinbao; Zhang, Nuowei; Yu, Changlin; Li, Yunhua; Pao, Chih-Wen; Chen, Jeng-Lung; Jin, Chuanhong; Lee, Jyh-Fu; Zhong, Chuan-Jian; Chen, Bing H

    2015-09-01

    The design of an ideal heterogeneous catalyst for hydrogenation reaction is to impart the catalyst with synergetic surface sites active cooperatively toward different reaction species. Herein a new strategy is presented for the creation of such a catalyst with dual active sites by decorating metal and metal oxide nanoparticles with ultrafine nanoclusters at atomic level. This strategy is exemplified by the design and synthesis of Ru nanoclusters supported on Ni/NiO nanoparticles. This Ru-nanocluster/Ni/NiO-nanoparticle catalyst is shown to exhibit ultrahigh catalytic activity for benzene hydrogenation reaction, which is 55 times higher than Ru-Ni alloy or Ru on Ni catalysts. The nanoclusters-on-nanoparticles are characterized by high-resolution transmission electron microscope, Cs-corrected high angle annular dark field-scanning transmission electron microscopy, elemental mapping, high-sensitivity low-energy ion scattering, and X-ray absorption spectra. The atomic-scale nanocluster-nanoparticle structural characteristics constitute the basis for creating the catalytic synergy of the surface sites, where Ru provides hydrogen adsorption and dissociation site, Ni acts as a "bridge" for transferring H species to benzene adsorbed and activated at NiO site, which has significant implications to multifunctional nanocatalysts design for wide ranges of catalytic reactions. PMID:26081741

  5. Exposure to inhalable, respirable, and ultrafine particles in welding fume.

    PubMed

    Lehnert, Martin; Pesch, Beate; Lotz, Anne; Pelzer, Johannes; Kendzia, Benjamin; Gawrych, Katarzyna; Heinze, Evelyn; Van Gelder, Rainer; Punkenburg, Ewald; Weiss, Tobias; Mattenklott, Markus; Hahn, Jens-Uwe; Möhlmann, Carsten; Berges, Markus; Hartwig, Andrea; Brüning, Thomas

    2012-07-01

    This investigation aims to explore determinants of exposure to particle size-specific welding fume. Area sampling of ultrafine particles (UFP) was performed at 33 worksites in parallel with the collection of respirable particles. Personal sampling of respirable and inhalable particles was carried out in the breathing zone of 241 welders. Median mass concentrations were 2.48 mg m(-3) for inhalable and 1.29 mg m(-3) for respirable particles when excluding 26 users of powered air-purifying respirators (PAPRs). Mass concentrations were highest when flux-cored arc welding (FCAW) with gas was applied (median of inhalable particles: 11.6 mg m(-3)). Measurements of particles were frequently below the limit of detection (LOD), especially inside PAPRs or during tungsten inert gas welding (TIG). However, TIG generated a high number of small particles, including UFP. We imputed measurements

  6. Fabrication of ultra-fine nanostructures using edge transfer printing.

    PubMed

    Xue, Mianqi; Li, Fengwang; Cao, Tingbing

    2012-03-21

    The exploration of new methods and techniques for application in diverse fields, such as photonics, microfluidics, biotechnology and flexible electronics is of increasing scientific and technical interest for multiple uses over distance of 10-100 nm. This article discusses edge transfer printing--a series of unconventional methods derived from soft lithography for nanofabrication. It possesses the advantages of easy fabrication, low-cost and great serviceability. In this paper, we show how to produce exposed edges and use various materials for edge transfer printing, while nanoskiving, nanotransfer edge printing and tunable cracking for nanogaps are introduced. Besides this, different functional materials, such as metals, inorganic semiconductors and polymers, as well as localised heating and charge patterning, are described here as unconventional "inks" for printing. Edge transfer printing, which can effectively produce sub-100 nm scale ultra-fine structures, has broad applications, including metallic nanowires as nanoelectrodes, semiconductor nanowires for chemical sensors, heterostructures of organic semiconductors, plasmonic devices and so forth. PMID:22344574

  7. Ultrafine MnWO4 nanoparticles and their magnetic properties

    NASA Astrophysics Data System (ADS)

    Ungelenk, Jan; Roming, Sabine; Adler, Peter; Schnelle, Walter; Winterlik, Jürgen; Felser, Claudia; Feldmann, Claus

    2015-08-01

    Ultrafine nanoparticles of MnWO4, a compound showing low-temperature multiferroicity in the bulk, were synthesized by the polyol method. Studies using powder X-ray diffraction, scanning and transmission electron microscopy, dynamic light scattering, differential sedimentation and sorption techniques show the formation of a single-phase material, which is composed of MnWO4 nanoparticles with a prolate ellipsoidal shape (short axis of 4-5 nm, long axis of 11-12 nm) and an unprecedented high specific surface area of 166 m2 g-1. The as-prepared MnWO4 nanoparticles are readily crystalline after the liquid-phase synthesis. Temperature and field dependent magnetization measurements indicate antiferromagnetic behavior with a single magnetic phase transition near TN ≈ 6 K. In contrast, three successive transitions below 14 K were reported for multiferroic bulk-MnWO4. Above TN, the nanoparticles show Curie-Weiss-type paramagnetic behavior. Due to the large paramagnetic moment of Mn2+ (μeff ≈ 6.2 μB), the nanoparticles can be easily manipulated by a bar magnet at ambient temperature.

  8. Recycling concrete: An undiscovered source of ultrafine particles

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Morawska, Lidia

    2014-06-01

    While concrete recycling is practiced worldwide, there are many unanswered questions in relation to ultrafine particle (UFP; Dp < 100 nm) emissions and exposure around recycling sites. In particular: (i) Does recycling produce UFPs and in what quantities? (ii) How do they disperse around the source? (iii) What impact does recycling have on ambient particle number concentrations (PNCs) and exposure? (iv) How effective are commonly used dust respirators to limit exposure? We measured size-resolved particles in the 5-560 nm range at five distances between 0.15 and 15.15 m that were generated by an experimentally simulated concrete recycling source and found that: (i) the size distributions were multimodal, with up to ˜93% of total PNC in the UFP size range; and (ii) dilution was a key particle transformation mechanism. UFPs showed a much slower decay rate, requiring ˜62% more distance to reach 10% of their initial concentration compared with their larger counterparts in the 100-560 nm size range. Compared with typical urban exposure during car journeys, exposure decay profiles showed up to ˜5 times higher respiratory deposition within 10 m of the source. Dust respirators were found to remove half of total PNC; however the removal factor for UFPs was only ˜57% of that observed in the 100-560 nm size range. These findings highlight a need for developing an understanding of the nature of the particles as well as for better control measures to limit UFP exposure.

  9. Outdoor ultrafine particle concentrations in front of fast food restaurants.

    PubMed

    Vert, Cristina; Meliefste, Kees; Hoek, Gerard

    2016-01-01

    Ultrafine particles (UFPs) have been associated with negative effects on human health. Emissions from motor vehicles are the principal source of UFPs in urban air. A study in Vancouver suggested that UFP concentrations were related to density of fast food restaurants near the monitoring sites. A previous monitoring campaign could not separate the contribution of restaurants from road traffic. The main goal of this study has been the quantification of fast food restaurants' contribution to outdoor UFP concentrations. A portable particle number counter (DiscMini) has been used to carry out mobile monitoring in a largely pedestrianized area in the city center of Utrecht. A fixed route passing 17 fast food restaurants was followed on 8 days. UFP concentrations in front of the restaurants were 1.61 times higher than in a nearby square without any local sources used as control area and 1.22 times higher compared with all measurements conducted in between the restaurants. Adjustment for other sources such as passing mopeds, smokers or candles did not explain the increase. In conclusion, fast food restaurants result in significant increases in outdoor UFP concentrations in front of the restaurant. PMID:26531805

  10. Microalloying Ultrafine Grained Al Alloys with Enhanced Ductility

    PubMed Central

    Jiang, L.; Li, J. K.; Cheng, P. M.; Liu, G.; Wang, R. H.; Chen, B. A.; Zhang, J. Y.; Sun, J.; Yang, M. X.; Yang, G.

    2014-01-01

    Bulk ultrafine grained (UFG)/nanocrystal metals possess exceptional strength but normally poor ductility and thermal stability, which hinder their practical applications especially in high-temperature environments. Through microalloying strategy that enables the control of grains and precipitations in nanostructured regime, here we design and successfully produce a highly microstructure-stable UFG Al-Cu-Sc alloy with ~275% increment in ductility and simultaneously ~50% enhancement in yield strength compared with its Sc-free counterpart. Although the precipitations in UFG alloys are usually preferentially occurred at grain boundaries even at room temperature, minor Sc addition into the UFG Al-Cu alloys is found to effectively stabilize the as-processed microstructure, strongly suppress the θ-Al2Cu phase precipitation at grain boundary, and remarkably promote the θ′-Al2Cu nanoparticles dispersed in the grain interior in artificial aging. A similar microalloying strategy is expected to be equally effective for other UFG heat-treatable alloys. PMID:24398915