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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

    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.

  16. 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

  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. 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

  9. 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

  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. 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

  18. 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

  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. 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.

  1. 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.

  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. 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

  13. 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

  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. 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.

  17. 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.

  18. [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

  19. 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.

  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. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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...

  8. 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 ...

  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. 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.

  13. 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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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

  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. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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

  18. 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

  19. 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

  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. 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

  3. 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 ...

  4. 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...

  5. 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,...

  6. 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...

  7. 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.

  8. 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...

  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

    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

  12. 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.

  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. 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

  7. 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.

  8. 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

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  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. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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

  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. 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

  8. 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

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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.

  20. 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%.

  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. 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.

  16. 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.

  17. 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

  18. [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

  19. 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.

  20. 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).

  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. 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.

  3. 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

  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. 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

  14. 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.

  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

    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

  2. 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

  3. 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.

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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

  9. 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

  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

  11. Ultrafine particle size as a tracer for aircraft turbine emissions

    NASA Astrophysics Data System (ADS)

    Riley, Erin A.; Gould, Timothy; Hartin, Kris; Fruin, Scott A.; Simpson, Christopher D.; Yost, Michael G.; Larson, Timothy

    2016-08-01

    Ultrafine particle number (UFPN) and size distributions, black carbon, and nitrogen dioxide concentrations were measured downwind of two of the busiest airports in the world, Los Angeles International Airport (LAX) and Hartsfield-Jackson International Airport (ATL - Atlanta, GA) using a mobile monitoring platform. Transects were located between 5 km and 10 km from the ATL and LAX airports. In addition, measurements were taken at 43 additional urban neighborhood locations in each city and on freeways. We found a 3-5 fold increase in UFPN concentrations in transects under the landing approach path to both airports relative to surrounding urban areas with similar ground traffic characteristics. The latter UFPN concentrations measured were distinct in size distributional properties from both freeways and across urban neighborhoods, clearly indicating different sources. Elevated concentrations of Black Carbon (BC) and NO2 were also observed on airport transects, and the corresponding pattern of elevated BC was consistent with the observed excess UFPN concentrations relative to other urban locations.

  12. Preparation of Ultrafine W-Cu Composite Powder Using Ultrasonic-Assisted Electroless Plating

    NASA Astrophysics Data System (ADS)

    Huang, Limei; Luo, Laima; Ding, Xiaoyu; Zan, Xiang; Hong, Yu; Cheng, Jigui; Wu, Yucheng; Luo, Guangnan; Zhu, Liu

    2013-07-01

    W-Cu ultrafine/nanocomposite powders have high sintering activity, so ultrafine/nanotechnology of W-Cu composite powders is one of the main methods to obtain fully dense, high-performance W-Cu composite materials. Cu-coated ultrafine W composite powders were synthesized by ultrasonic-assisted electroless plating process with non-noble metal activation pretreatment at room temperature in this paper. The growth mechanism of Cu layers and surface morphologies and composition of initial ultrafine W powders, pretreated W powders and Cu-coated W powders were analyzed by field emission scanning electron microscopy (FE-SEM), and energy dispersion spectrometry (EDS). The results show that the uniformly Cu coated W composite powder is successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Cu layers on the ultrafine W powders had cell structure with dense, uniform distribution. The growth mechanism of Cu layers appears as follows: the surfaces of pretreated W powders appear linear-like and lamellar-like surface defects which act as activated sites. The reactants in the plating solution were adsorbed on catalytic activity surfaces of powders and happened oxidation-reduction reaction. The growth and aggregation mechanisms of Cu particles after nucleation are stripy Cu-cells grew up, bend, bifurcated, and aggregated, then wounding into a cellular structure, like "wrapping wool clusters" in the life. Finally, Cu cells grow up and merge into a layer.

  13. Effect of Initial Microstructure on Impact Toughness of 1200 MPa-Class High Strength Steel with Ultrafine Elongated Grain Structure

    NASA Astrophysics Data System (ADS)

    Jafari, Meysam; Garrison, Warren M.; Tsuzaki, Kaneaki

    2014-02-01

    A medium-carbon low-alloy steel was prepared with initial structures of either martensite or bainite. For both initial structures, warm caliber-rolling was conducted at 773 K (500 °C) to obtain ultrafine elongated grain (UFEG) structures with strong <110>//rolling direction (RD) fiber deformation textures. The UFEG structures consisted of spheroidal cementite particles distributed uniformly in a ferrite matrix of a transverse grain size of about 331 and 311 nm in samples with initial martensite and bainite structures, respectively. For both initial structures, the UFEG materials had similar tensile properties, upper shelf energy (145 J), and ductile-to-brittle transition temperatures 98 K (500 °C). Obtaining the martensitic structure requires more rapid cooling than is needed to obtain the bainitic structure and this more rapid cooling promote cracking. As the UFEG structures obtained from initial martensitic and bainitic structures have almost identical properties, but obtaining the bainitic structure does not require a rapid cooling which promotes cracking suggests the use of a bainitic structure in obtaining UFEG structures should be examined further.

  14. Direct crystallization of perovskite phase in PMN-PT thin films prepared by polyvinylpyrrolidone modified sol-gel processing and their properties

    SciTech Connect

    Du, Z.H.; Zhang, T.S.; Zhu, M.M.; Ma, J.

    2009-07-15

    A modified sol-gel processing has been developed by using polyvinylpyrrolidone (PVP) as modifier and lead nitrate as lead source to synthesize (1-x)Pb(Mg{sub 1/3},Nb{sub 2/3})O{sub 3}-xPbTiO{sub 3} (PMN-PT) thin films with x=0.23-0.43. With PVP additions, perovskite phase could directly crystallize from amorphous films at the temperature as low as 430 deg. C via bypassing the metastable phase-pyrochlore and crystallinity was significantly enhanced. The PVP addictives have been optimized with molecular weight <630 K and the ratio of PVP monomer/PMN-PT at 0.25-1.0. XPS analysis indicates that the chemical states of the elements in the well-crystallized PMN-PT films are close to the literature data for the PMN-PT single crystals and the films possess highly desired electrical and optical properties. - Graphical abstract: A polyvinylpyrrolidone modified sol-gel processing was developed to synthesize pure-perovskite Pb(Mg{sub 1/3},Nb{sub 2/3})O{sub 3}-PbTiO{sub 3} films via bypassing pyrochlore phase.

  15. ULTRAFINE CARBON PARTICLES INDUCE IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS THROUGH A POST-TRANSCRIPTIONAL MECHANISM

    EPA Science Inventory

    Ultrafine carbon particles induce IL-8 expression in human airway
    epithelial cells through a post-transcritpional mechanism
    Epidemiological studies suggest that ultrafine particles contribute to
    particulate matter (PM) - induced adverse health effects. IL-8 is an
    i...

  16. Effect of multidirectional forging and equal channel angular pressing on ultrafine grain formation in a Cu- Cr-Zr alloy

    NASA Astrophysics Data System (ADS)

    Shakhova, I.; Belyakov, A.; Kaibyshev, R.

    2014-08-01

    The microstructure evolution was investigated in a Cu-0.3%Cr-0.5%Zr alloy subjected to large plastic deformation at temperature of 400 °C. Two methods of large plastic deformation, i.e., equal channel angular pressing (ECAP) and multidirectional forging (MDF) were used. The large plastic deformations resulted in the development of new ultrafine grains. The formation of new ultrafine grains occurred as a result of continuous reaction, i.e., progressive increase in the misorientations of deformation subboundaries. The faster kinetics of microstructure evolution was observed during MDF as compared to ECAP. The MDF to a total strain of 4 resulted in the formation of uniform ultrafine grained structure, while ECAP to the same strain led to the heterogeneous microstructure consisting of new ultrafine grains and coarse remnants of original grains. Corresponding area fractions of ultrafine grains comprised 0.23 and 0.59 in the samples subjected to ECAP and MDF, respectively.

  17. The superior lithium storage capabilities of ultra-fine rutile TiO 2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Jun Song; Lou, Xiong Wen

    The lithium storage capabilities of ultra-fine rutile TiO 2 nanoparticles have been studied. Ultra-fine rutile TiO 2 nanoparticles with only several nanometers in size have been prepared by a modified wet-chemical method with a high yield. Unexpectedly, the rutile TiO 2 nanoparticles with 3 nm in size exhibit superior lithium storage properties. Specifically, they show long term cycling stability upon extended cycling for at least 300 cycles with a capacity loss of only 0.17% per cycle, and good rate capability up to a 30 C rate. The excellent reversible lithium storage capabilities could be attributed to the ultra-fine size giving rise to a very short diffusion path, and the relatively large surface area which provides more sites for lithium insertion.

  18. Strength and ductility improvement of ultrafine-grained tungsten produced by equal-channel angular pressing

    NASA Astrophysics Data System (ADS)

    Hao, T.; Fan, Z. Q.; Zhang, T.; Luo, G. N.; Wang, X. P.; Liu, C. S.; Fang, Q. F.

    2014-12-01

    In this study, equal-channel angular pressing (ECAP) was employed to refine the grain size of tungsten at relatively low temperatures. The small punch (SP) test results show that the ultrafine-grained tungsten appears an evident improvement in both strength and ductility compared with primary coarse-grained tungsten. The analysis results from SP test data indicate that the ductile-to-brittle transition temperature (DBTT) of the ultrafine-grained tungsten decrease to 386 °C and 322 °C due to the ECAP processing at 800 °C and 950 °C, respectively. The reason of the improvement in both strength and ductility of the ultrafine-grained tungsten produced by ECAP is discussed.

  19. Preparation and mechanical properties of silicon oxycarbide fibers from electrospinning/sol-gel process

    SciTech Connect

    Wang, Xiaofei; Gong, Cairong; Fan, Guoliang

    2011-12-15

    Graphical abstract: Ceramic fibers, silicon oxycarbide (SiOC) fibers were demonstrated and showed higher mechanical properties from electrospinning/sol-gel process at 1000 Degree-Sign C. Highlights: Black-Right-Pointing-Pointer SiOC fibers with low cost are promising to substitute the non-oxide fibers. Black-Right-Pointing-Pointer Successful preparation of SiOC fibers by electrospinning/sol-gel process. Black-Right-Pointing-Pointer Confirmation of the designed product using material characterization methods. Black-Right-Pointing-Pointer The SiOC fibers prepared at 1000 Degree-Sign C possess higher strength (967 MPa). -- Abstract: Silicon oxycarbide (SiOC) fibers were produced through the electrospinning of the solution containing vinyltrimethoxysilane and tetraethoxysilane in the course of sol-gel reaction with pyrolysis to ceramic. The effect of the amount of spinning agent Polyvinylpyrrolidone (PVP) on the dope spinnability was investigated. At a mass ratio of PVP/alkoxides = 0.05, the spinning sol exhibited an optimal spinnable time of 50 min and generated a large quantity of fibers. Electrospun fibers were characterized by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis-differential scanning calorimetry (TGA-DSC), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM results revealed that the SiOC fibers had a smooth surface and dense cross-section, free of residue pores and cracks. The XPS results gave high content of SiC (13.99%) in SiOC fibers. The SiOC fibers prepared at 1000 Degree-Sign C had a high tensile strength of 967 MPa and Young's modulus of 58 GPa.

  20. What does respirator certification tell us about filtration of ultrafine particles?

    PubMed

    Eninger, Robert M; Honda, Takeshi; Reponen, Tiina; McKay, Roy; Grinshpun, Sergey A

    2008-05-01

    Recent interest in exposures to ultrafine particles (less than 100 nm) in both environmental and occupational settings led the authors to question whether the protocols used to certify respirator filters provide adequate attention to ultrafine aerosols. The authors reviewed the particle size distribution of challenge aerosols and evaluated the aerosol measurement method currently employed in the National Institute for Occupational Safety and Health (NIOSH) particulate respirator certification protocol for its ability to measure the contribution of ultrafine particles to filter penetration. Also considered were the differences between mechanical and electrically charged (electret) filters in light of the most penetrating particle size. It was found that the sodium chloride (NaCl) and dioctylphthalate (DOP) aerosols currently used in respirator certification tests contain a significant fraction of particles in the ultrafine region. However, the photometric method deployed in the certification test is not capable of adequately measuring light scatter of particles below approximately 100 nm in diameter. Specifically, 68% (by count) and 8% (by mass) of the challenge NaCl aerosol particles and 10% (by count) and 0.3% (by mass) of the DOP particles below 100 nm do not significantly contribute to the filter penetration measurement. In addition, the most penetrating particle size for electret filters likely occurs at 100 nm or less under test conditions similar to those used in filter certification. The authors conclude, therefore, that the existing NIOSH certification protocol may not represent a worst-case assessment for electret filters because it has limited ability to determine the contribution of ultrafine aerosols, which include the most penetrating particle size for electret filters. Possible strategies to assess ultrafine particle penetration in the certification protocol are discussed. PMID:18322869

  1. Two Fiber Optical Fiber Thermometry

    NASA Technical Reports Server (NTRS)

    Jones, Mathew R.; Farmer, Jeffery T.; Breeding, Shawn P.

    2000-01-01

    An optical fiber thermometer consists of an optical fiber whose sensing tip is given a metallic coating. The sensing tip of the fiber is essentially an isothermal cavity, so the emission from this cavity will be approximately equal to the emission from a blackbody. Temperature readings are obtained by measuring the spectral radiative heat flux at the end of the fiber at two wavelengths. The ratio of these measurements and Planck's Law are used to infer the temperature at the sensing tip. Optical fiber thermometers have high accuracy, excellent long-term stability and are immune to electromagnetic interference. In addition, they can be operated for extended periods without requiring re-calibration. For these reasons. it is desirable to use optical fiber thermometers in environments such as the International Space Station. However, it has recently been shown that temperature readings are corrupted by emission from the fiber when extended portions of the probe are exposed to elevated temperatures. This paper will describe several ways in which the reading from a second fiber can be used to correct the corrupted temperature measurements. The accuracy and sensitivity to measurement uncertainty will be presented for each method.

  2. Ultrafine-grained titanium of high interstitial contents with a good combination of strength and ductility

    NASA Astrophysics Data System (ADS)

    Xu, W.; Wu, X.; Sadedin, D.; Wellwood, G.; Xia, K.

    2008-01-01

    A dehydrided Ti powder of very high oxygen content was successfully consolidated using back pressure equal channel angular processing into a fully dense bulk ultrafine-grained Ti showing apparent compressive ductility as well as high true yield and ultimate strengths of 1350 and 1780MPa, respectively. Interstitial solid solution strengthening contributed to the majority of the increase in strength with additional contribution from ultrafine grains. Significantly, the material also exhibited much improved ductility for such a high interstitial content, thanks probably to the nonequilibrium grain boundaries and bimodal grain structure introduced during severe plastic deformation.

  3. Purification of single-wall carbon nanotubes by using ultrafine gold particles

    NASA Astrophysics Data System (ADS)

    Nihey, Fumiyuki; Mizoguti, Eiji; Yudasaka, Masako; Iijima, Sumio; Ichihashi, Toshinari; Nakamura, Kazuo

    2000-03-01

    The purification of single-wall carbon nanotubes (SWNTs) is needed to enable detailed characterization and some application of this material. We report a purification method utilizing ultrafine gold particles as catalysts to selectively oxidize carbonaceous impurities in SWNT soot. The ultrafine gold particles with a diameter of 20 nm were dispersed in the soot in combination with benzalkonium chloride as surfactant. Thermogravimetric analyses and electron microscopy observations revealed that oxidation occured at about 330^circC for carbonaceous impurities and at about 410^circC for SWNTs. This selective oxidation enabled us to purify SWNTs and make the quantitative analyses of SWNTs.

  4. Effect of surface moisture on dielectric behavior of ultrafine BaTiO3 particulates.

    NASA Technical Reports Server (NTRS)

    Mountvala, A. J.

    1971-01-01

    The effects of adsorbed H2O on the dielectric properties of ultrafine BaTiO3 particulates of varying particle size and environmental history were determined. The dielectric behavior depends strongly on surface hydration. No particle size dependence of dielectric constant was found for dehydroxylated surfaces in ultrafine particulate (unsintered) BaTiO3 materials. For equivalent particle sizes, the ac conductivity is sensitive to surface morphology. Reactions with H2O vapor appear to account for the variations in dielectric properties. Surface dehydration was effectively accomplished by washing as-received powders in isopropanol.

  5. Iron Fischer-Tropsch catalysis: Properties of an ultrafine iron oxide catalyst

    SciTech Connect

    Xu, Liguang; Bao, Shiqi; O'Brien, R.; Houpt, D.; Davis, B.H.

    1992-01-01

    A commercial Fe oxide with a particle size of 3 nm is now available. The FT requires considerable time on stream before steady state conditions are attained. Since it is desirable to obtain FT data for the smaller ultrafine Fe oxide catalysts at larger times on steam, data for operation up to 6 months were collected using slurry phase. Results show that the ultrafine Fe oxide maintain catalytic activity for a 150-day operating period. Addition of 0.5% K increased the activity; after 56 days, the activity had declined to and below that of unpromoted catalyst. Neither the unpromoted nor K-promoted catalyst exhibited good selectivity for alkenes.

  6. Heterogeneous plastic deformation and Bauschinger effect in ultrafine-grained metals: atomistic simulations

    NASA Astrophysics Data System (ADS)

    Tsuru, Tomohito; Aoyagi, Yoshiteru; Kaji, Yoshiyuki; Shimokawa, Tomotsugu

    2016-03-01

    The effect of the dislocation density on yield strength and subsequent plastic deformation of ultrafine-grained metals was investigated in large-scale atomistic simulations. Polycrystalline models were constructed and uniaxial tension and compression were applied to elucidate the heterogeneous plastic deformation and the Bauschinger effect. The initial yield becomes heterogeneous as the dislocation density decreases owing to a wide range of Schmid factors of activated slip systems in each grain. A different mechanism of the Bauschinger effect was proposed, where the Bauschinger effect of ultrafine-grained metals is caused by the change in dislocation density in the process of forward and backward loadings.

  7. Micro-to-nano-scale deformation mechanisms of a bimodal ultrafine eutectic composite

    PubMed Central

    Lee, Seoung Wan; Kim, Jeong Tae; Hong, Sung Hwan; Park, Hae Jin; Park, Jun-Young; Lee, Nae Sung; Seo, Yongho; Suh, Jin Yoo; Eckert, Jürgen; Kim, Do Hyang; Park, Jin Man; Kim, Ki Buem

    2014-01-01

    The outstading mechanical properties of bimodal ultrafine eutectic composites (BUECs) containing length scale hierarchy in eutectic structure were demonstrated by using AFM observation of surface topography with quantitative height measurements and were interpreted in light of the details of the deformation mechanisms by three different interface modes. It is possible to develop a novel strain accommodated eutectic structure for triggering three different interface-controlled deformation modes; (I) rotational boundary mode, (II) accumulated interface mode and (III) individual interface mode. A strain accommodated microstructure characterized by the surface topology gives a hint to design a novel ultrafine eutectic alloys with excellent mechanical properties. PMID:25265897

  8. Ultrafine particles of iron in Fischer-Tropsch synthesis

    SciTech Connect

    Mahajan, D.; Pandya, K.

    1994-12-31

    Though direct combustion of natural gas is the most efficient use of this abundant, inexpensive, and cleaner fossil fuel, its potential to replace existing less efficient feedstocks for downstream processes is enormous. Direct conversion of methane to useful products under mild conditions is an ongoing area of research, and a few reported successes include higher hydrocarbons (C{sub 2}-C{sub 6}) synthesis on Pt at 250{degrees}C, Hg-catalyzed synthesis of methanol at 180{degrees}C, and acetic acid synthesis catalyzed by aqueous RhCl{sub 3} at 100{degrees}C. Since these approaches are in early stages of development, improvements in other known routes are of interest. Fischer-Tropsch (F-T) synthesis is an indirect route to catalytic production of liquid fuels from synthesis gas derived from carbonaceous sources. The process is still uneconomical for widespread use due to low space-time-yield (STY), low product selectivity, and catalyst intolerance to sulfur. To address these aspects, a few reports describe the use of ultrafine particle (UFP) catalysts in slurry-phase F-T synthesis, We recently reported that a commercially available unsupported UFP FeZO{sub 3} material (NANOCAT{trademark}) (Mean particle diameter (MPD) = 3 nm; surface area (SA) - 255 m{sup 2}/g) slurried in a C{sub 30} hydrocarbon solvent, after reduction at 280{degrees}C under CO, catalyzed conversion of balanced synthesis gas (H{sub 2}/CO = 2/1) at {>=} 220{degrees}C and {<=} 3 MPa. Described below are additional runs carried out to further scrutinize the Fe UFP system.

  9. Ultrafine particle removal and generation by portable air cleaners

    NASA Astrophysics Data System (ADS)

    Waring, Michael S.; Siegel, Jeffrey A.; Corsi, Richard L.

    Portable air cleaners can both remove and generate pollutants indoors. To investigate these phenomena, we conducted a two-phase investigation in a 14.75 m 3 stainless steel chamber. In the first phase, particle size-resolved (12.6-514 nm diameter) clean air delivery rates (CADR) and efficiencies were determined, as were ozone emission rates, for two high-efficiency particle arresting (HEPA) filters, one electrostatic precipitator with a fan, and two ion generators without fans. The two HEPA air cleaners had count average CADR (standard deviation) of 188 (30) and 324 (44) m 3 h -1; the electrostatic precipitator 284 (62) m 3 h -1; and the two ion generators 41 (11) and 35 (13) m 3 h -1. The electrostatic precipitator emitted ozone at a rate of 3.8±0.2 mg h -1, and the two ion generators 3.3±0.2 and 4.3±0.2 mg h -1. Ozone initiates reactions with certain unsaturated organic compounds that produce ultrafine and fine particles, carbonyls, other oxidized products, and free radicals. During the second phase, five different ion generators were operated separately in the presence of a plug-in liquid or solid air freshener, representing a strong terpene source. For air exchange rates of between 0.49 and 0.96 h -1, three ion generators acted as steady-state net particle generators in the entire measured range of 4.61-157 nm, and two generated particles in the range of approximately 10 to 39-55 nm. Terpene and aldehyde concentrations were also sampled for one ion generator, and concentrations of terpenes decreased and formaldehyde increased. Given these results, the pollutant removal benefits of ozone-generating air cleaners may be outweighed by the generation of indoor pollution.

  10. Fine and ultrafine particle decay rates in multiple homes.

    PubMed

    Wallace, Lance; Kindzierski, Warren; Kearney, Jill; MacNeill, Morgan; Héroux, Marie-Ève; Wheeler, Amanda J

    2013-11-19

    Human exposure to particles depends on particle loss mechanisms such as deposition and filtration. Fine and ultrafine particles (FP and UFP) were measured continuously over seven consecutive days during summer and winter inside 74 homes in Edmonton, Canada. Daily average air exchange rates were also measured. FP were also measured outside each home and both FP and UFP were measured at a central monitoring station. A censoring algorithm was developed to identify indoor-generated concentrations, with the remainder representing particles infiltrating from outdoors. The resulting infiltration factors were employed to determine the continuously changing background of outdoor particles infiltrating the homes. Background-corrected indoor concentrations were then used to determine rates of removal of FP and UFP following peaks due to indoor sources. About 300 FP peaks and 400 UFP peaks had high-quality (median R(2) value >98%) exponential decay rates lasting from 30 min to 10 h. Median (interquartile range (IQR)) decay rates for UFP were 1.26 (0.82-1.83) h(-1); for FP 1.08 (0.62-1.75) h(-1). These total decay rates included, on average, about a 25% contribution from air exchange, suggesting that deposition and filtration accounted for the major portion of particle loss mechanisms in these homes. Models presented here identify and quantify effects of several factors on total decay rates, such as window opening behavior, home age, use of central furnace fans and kitchen and bathroom exhaust fans, use of air cleaners, use of air conditioners, and indoor-outdoor temperature differences. These findings will help identify ways to reduce exposure and risk. PMID:24143863

  11. Fluxes of Ultrafine Particles Over and In a Deciduous Forest

    NASA Astrophysics Data System (ADS)

    Pryor, S. C.; Hornsby, K. E.

    2013-12-01

    Given the importance of forests to land surface cover and particle removal (due to the very high deposition velocities and well-developed turbulence) there is a specific need to understand removal to, and in, forests. Fluxes of size-resolved and total particle number fluxes over (at 46 m) and in (at 7 m) a deciduous forest over a 14 month period are presented based on data from two Gill 3-D WindMaster Pro sonic anemometers, an Ultrafine Condensation Particle Counter (UCPC) operated at 10 Hz and a Fast Mobility Particle Sizer (FMPS) operated at 1 Hz. Size-resolved particle profiles during the same period are measured using a separate FMPS scanning at three measurement heights across the canopy (top, middle and bottom). Three methods are being applied to derive the total number and size-resolved fluxes from the UCPC and FMPS respectively; eddy covariance, inertial dissipation and the co-spectral approach. The results are integrated with fluxes of sensible heat, momentum and carbon dioxide derived using a Licor LI-7200. Results for the total number flux concentrations and the size-resolved concentrations derived using the three different approaches applied to the above canopy sampling level show a high degree of accord, but that the eddy-covariance fluxes are generally of smaller magnitude than those derived using the spectral methods. In keeping with prior research our results show a considerable number of fluxes are characterized by upward fluxes. Further our results show distinctly different flux diurnal profiles for the nucleation versus Aitken mode particles indicating some differential control on fluxes of particles of different sizes (including a role for aerosol dynamics). This presentation will provide details regarding the experimental approach, flux and gradient estimation methodologies, diagnose the size dependence of the fluxes, and compare and contrast the canopy and ground partitioning of the particle fluxes during leaf-on and leaf-off periods.

  12. Roadside measurements of ultrafine particles at a busy urban intersection.

    PubMed

    Wang, Yungang; Zhu, Yifang; Salinas, Robert; Ramirez, David; Karnae, Saritha; John, Kuruvilla

    2008-11-01

    A field sampling campaign on ultrafine particles (UFPs, diameter <100 nm) was conducted at a busy traffic intersection from December 2006 to June 2007 in Corpus Christi, TX. This traffic intersection consisted of South Padre Island Drive (SPID, Highway 358) and Staples Street. Traffic densities on SPID were 9102/hr and 7880/hr for weekdays and weekends, respectively. Staples Street traffic densities were 2795/hr and 2572/hr, respectively. There were approximately 3.7% heavy-duty diesel vehicles (HDDVs) on both roadways. Peak traffic flows occurred early in the morning and late in the evening during weekdays and around noon on weekends. The average UFP total number concentration collected by a condensation particle counter (CPC 3785; TSI) was 66 x 10(3) cm(-3). A direct relationship between the UFP number concentration and traffic density was observed, but the HDDV traffic density was found to be a better estimator of the UFP number concentration than total traffic density. A scanning mobility particle sizer (SMPS 3936 with DMA 3081 and CPC 3785, TSI) measuring the particle size distribution from 7 to 290 nm was rotated among four corners of the intersection. The upwind and downwind size distributions were both bimodal in shape, exhibiting a nucleation mode at 10-30 nm and a secondary mode at 50-70 nm. The highest and lowest particle concentrations were observed on the downwind and upwind sides of both roadways, respectively, indicating the importance of wind direction. Wind speed also played an important role in overall particle concentrations; UFP concentrations were inversely proportional to wind speed. A negative correlation was observed between particle number concentrations and ambient temperature. The particle number concentration was 3.5 times greater when traffic was idling at a red light than moving at a green light. PMID:19044160

  13. Ultrafine cement grout for sealing underground nuclear waste repositories

    SciTech Connect

    Ahrens, E.H.; Onofrei, M.

    1996-02-01

    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 their host. This paper presents the results of collaborative work between Whitesell Laboratories, operated by Atomic Energy of Canada, Ltd., and Sandia National Laboratories; the work was undertaken in support of the Waste Isolation Pilot Plant (WIPP). 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 plugging and sealing program, specifically the development and optimization of Ultrafine cementitious grout that can be injected to adequately lower excessive, strain-induced permeability in the Distributed Rock Zone (DRZ) surrounding underground excavations. Innovative equipment and procedures employed in the laboratory produced a usable cement-based grout whose particles are 90% smaller than 8 microns and average 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 8 microns and lowered the gas permeability of the DRZ by three orders of magnitude. Following the WIPP test, additional work produced an improved version of the grout containing particles 90% smaller than 6 microns and averaging 2 microns. This grout can be produced in the dry form at a competitive cost ready to mix.

  14. Optical Fibers

    NASA Astrophysics Data System (ADS)

    Ghatak, Ajoy; Thyagarajan, K.

    With the development of extremely low-loss optical fibers and their application to communication systems, a revolution has taken fiber glass place during the last 40 years. In 2001, using glass fibers as the transmission medium and lightwaves as carrier wave waves, information was transmitted at a rate more than 1 Tbit/s (which is roughly equivalent to transmission of about 15 million simultaneous telephone conversations) through one hair thin optical fiber. Experimental demonstration of transmission at the rate of 14 Tbit/s over a 160 km long single fiber was demonstrated in 2006, which is equivalent to sending 140 digital high definition movies in 1 s. Very recently record transmission of more than 100 Tbit/s over 165 km single mode fiber has been reported. These can be considered as extremely important technological achievements. In this chapter we will discuss the propagation characteristics of optical fibers with special applications to optical communication systems and also present some of the noncommunication applications such as sensing.

  15. Electrospinning of Grooved Polystyrene Fibers: Effect of Solvent Systems

    NASA Astrophysics Data System (ADS)

    Liu, Wanjun; Huang, Chen; Jin, Xiangyu

    2015-05-01

    Secondary surface texture is of great significance to morphological variety and further expands the application areas of electrospun nanofibers. This paper presents the possibility of directly electrospinning grooved polystyrene (PS) fibers using both single and binary solvent systems. Solvents were classified as low boiling point solvent (LBPS): dichloromethane (DCM), acetone (ACE), and tetrahydrofuran (THF); high boiling point solvent (HBPS): N, N-dimethylformamide (DMF) and cyclohexanone (CYCo); and non-solvent (NS): 1-butanol (BuOH). By the systematic selection and combination of these solvents at given parameters, we found that single solvent systems produced non-grooved fibers. LBPS/DMF solvent systems resulted in fibers with different grooved textures, while LBPS/CYCo led to fibers with double grooved texture. Grooved fibers can also be fabricated from LBPS/LBPS, NS/LBPS, and NS/HBPS systems under specific conditions. The results indicated that the difference of evaporation rate (DER) between the two solvents played a key role in the formation of grooved texture. The formation of this unique texture should be attributed to three separate mechanisms, namely void-based elongation, wrinkle-based elongation, and collapsed jet-based elongation. Our findings can serve as guidelines for the preparation of ultrafine fibers with grooved secondary texture.

  16. Electrospinning of Grooved Polystyrene Fibers: Effect of Solvent Systems.

    PubMed

    Liu, Wanjun; Huang, Chen; Jin, Xiangyu

    2015-12-01

    Secondary surface texture is of great significance to morphological variety and further expands the application areas of electrospun nanofibers. This paper presents the possibility of directly electrospinning grooved polystyrene (PS) fibers using both single and binary solvent systems. Solvents were classified as low boiling point solvent (LBPS): dichloromethane (DCM), acetone (ACE), and tetrahydrofuran (THF); high boiling point solvent (HBPS): N,N-dimethylformamide (DMF) and cyclohexanone (CYCo); and non-solvent (NS): 1-butanol (BuOH). By the systematic selection and combination of these solvents at given parameters, we found that single solvent systems produced non-grooved fibers. LBPS/DMF solvent systems resulted in fibers with different grooved textures, while LBPS/CYCo led to fibers with double grooved texture. Grooved fibers can also be fabricated from LBPS/LBPS, NS/LBPS, and NS/HBPS systems under specific conditions. The results indicated that the difference of evaporation rate (DER) between the two solvents played a key role in the formation of grooved texture. The formation of this unique texture should be attributed to three separate mechanisms, namely void-based elongation, wrinkle-based elongation, and collapsed jet-based elongation. Our findings can serve as guidelines for the preparation of ultrafine fibers with grooved secondary texture. PMID:26055481

  17. Stretch and radial compression studies on relaxed skinned muscle fibers of the frog.

    PubMed Central

    Maughan, D W; Godt, R E

    1979-01-01

    The influence of stretch and radial compression on the width of mechanically skinned fibers from the semitendinosus muscle of the frog (R. pipiens) was examined in relaxing solutions with high-power light microscopy. Fibers were skinned under mineral oil. We find that, after correcting for water uptake in the oil, fiber width increased by an average of 28% upon transfer from oil to relaxing medium, with some tendency for greater swelling at longer sarcomere lengths. Subsequently, fibers were compressed by addition of the long-chain polymer polyvinylpyrrolidone (PVP-40, number average molecular weight 40,000) to relaxing solutions. Sarcomere length does not appear to be affected by addition of PVP. At any PVP concentration, the inverse square of the fiber width increased smoothly and linearly with increasing stretch for sarcomere lengths between 2.10 and 4.60 micrometer. At any fixed sarcomere length, fiber width decreased linearly with the logarithm of the osmotic compressive pressure exerted by PVP (2-10% concentration). From this logarithmic relation we estimate that the swelling pressure of the intact fiber is 3.40 x 10(3) N/m2, between that of a 2 and a 3% PVP solution. The pressure giving rise to fiber swelling is not due to dilation of the sarcoplasmic reticulum (SR), since the experimental results above were not significantly different after treatment with 0.5% BRIJ-58, a nonionic detergent that disrupts the SR. Swelling may be due simply to elastic structures within the fiber that are constrained in the intact cell. Values of bulk moduli of fibers, calculated from the compression experiments, and preliminary measurements of Young's modulus from stretch experiments, are quantitatively consistent with the idea that skinned fibers behave as nonisotropic elastic bodies. Images FIGURE 1 PMID:318072

  18. Fireblocking Fibers

    NASA Technical Reports Server (NTRS)

    1986-01-01

    PBI was originally developed for space suits. In 1980, the need for an alternative to asbestos and stricter government anti-pollution standards led to commercialization of the fire blocking fiber. PBI is used for auto racing driver suits and aircraft seat covers. The fiber does not burn in air, is durable and easily maintained. It has been specified by a number of airliners and is manufactured by Hoechst-Celanese Corporation.

  19. A comparison of the electrochemical behavior of carbon aerogels and activated carbon fiber cloths

    SciTech Connect

    Tran, T.D.; Alviso, C.T.; Hulsey, S.S.; Nielsen, J.K.; Pekala, R.W.

    1996-05-10

    Electrochemical capacitative behavior of carbon aerogels and commercial carbon fiber cloths was studied in 5M KOH, 3M sulfuric acid, and 0.5M tetrethylammonium tetrafluoroborate/propylene carbonate electrolytes. The resorcinol-formaldehyde based carbon aerogels with a range of denisty (0.2-0.85 g/cc) have open-cell structures with ultrafine pore sizes (5-50 nm), high surface area (400-700 m{sup 2}/g), and a solid matrix composed of interconnected particles or fibers with characteristic diameters of 10 nm. The commercial fiber cloths in the density range 0.2-04g/cc have high surface areas (1000-2500 m{sup 2}/g). The volumetric capacitances of high-density aerogels are shown to be comparable to or exceeding those from activated carbon fibers. Electrochemical behavior of these materials in various electrolytes is compared and related to their physical properties.

  20. Effect of polyethersulfone concentration on flat and hollow fiber membrane performance

    SciTech Connect

    Wood, H.; Wang, J. ); Sourirajan, S. )

    1993-11-01

    Flat and hollow fiber (HF) membranes are made in order to determine the effect of the polyethersulfone (PES) concentration in the precursor film-casting solution on the resultant flat and hollow fiber membrane performance. The additive polyvinylpyrrolidone (PVP) is included in the film-casting solution to ensure that membranes can be made over wide variations in the PES polymer concentration. In general, membrane permeability decreases and solute separation ability increases as the PES concentration increases. However, for both flat and HF membranes, performance is strongly dependent on whether the PES concentration is above or below the critical value. Flux greatly decreases and solute-separation ability increases when the critical PES concentration is at the critical value. 20 refs., 1 fig., 4 tabs.

  1. [DYNAMICS OF BACTERIOLOGICAL AND PLANIMETRIC INDICES OF THE WOUND UNDER THE ACTION OF THE SILVER NANOPARTICLES, STABILIZED BY MEXIDOL AND POLYVINYLPYRROLIDONE].

    PubMed

    Lyakhovskyi, V I; Lobahn, G A; Gancho, O V; Vazhnycha, O M; Kolomiyets, S V; Jaber, V Kh O

    2016-04-01

    Changes in bacteriological indices through the square of the wound of chemical origin under local impact of the silver nanoparticles (NP), stabilized by 2-ethyl-6-methyl-3-hydroxypyridine succinate (mexidol) and polyvinylpyrrolidone were studied. The wounds of submandibular region were simulated in white rats, using injection of 10% solution of calcium chloride with further opening of necrotic foci and open management of the wound. Beginning from the fifth day, every day the wound was irrigated with liquid, which have contented the stabilized NP of the silver, 0.05% water solution of chlorhexidine or isotonic solution of the the sodium chloride (control). There was established, that the silver NP impact antiseptically and regenerative while the wound treatment, and reduce during 10 days microbial contamination of exudate in 24 times, the wound square--in three times in comparison with original indices. These changes were identical to those while application of chlorhexidine. PMID:27434961

  2. Comparative study of the effects of treatment with diethyleneiminebenzoquinone and its polymer complex with polyvinylpyrrolidone on the primary response of mice to sheep red blood cells.

    PubMed

    Kostadinov, D A; Popov, D V

    1978-05-01

    The primary response of BALB/c mice to sheep red blood cells was used to study comparatively the time-dependent effects of a 5-day course of treatment with equivalent doses (0.8 mg/kg of body weight every day) of the cytotoxic agent diethyleneiminebenzoquinone (DEiBq) and its polymer complex with polyvinylpyrrolidone (DEiBqPVP). The experimental results show that in contrast to treatment with DEiBq, the ability of treated mice to establish a specific immune response was not markedly impaired during the treatment with DEiBqPVP. The possible significance of these results is considered with reference to the use of the synthetic polymer PVP as a carrier of cytotoxic groups in experimental cancer chemotherapy. PMID:556384

  3. Determination of thickness and optical constants of solgel derived polyvinylpyrrolidone/ZrO2 films from transmission spectra using different dispersion models.

    PubMed

    Jia, Hongbao; Sun, Jinghua; Xu, Yao; Wu, Dong

    2012-10-10

    Transmission measurements have been used to investigate the optical properties of polyvinylpyrrolidone (PVP)/ZrO(2) films synthesized by the solgel route. The optical constants of PVP/ZrO(2) films deposited on quartz substrates were determined by fitting transmission spectra in the wavelength range of 200-800 nm with the Tauc-Lorentz and Cody-Lorentz physical models. Combined with Urbach tail, both models give a good description of transmission data and reveal that refractive index of film slightly decreases with increasing PVP mass fraction. X-ray reflectivity (XRR) measurements were also performed on PVP/ZrO(2) films to complement the thicknesses. The value of film thickness, including interface information from transmission spectra, is consistent with that result obtained from XRR, indicating that fitting transmission spectrum is a high reliable optical characterization. PMID:23052070

  4. Polyvinylpyrrolidone-sodium dodecylsulfate complex is a family of pseudo-polyanions with different charge densities: Evidence from capillary electrophoresis, capillary viscosimetry and conductometry.

    PubMed

    Wu, Yefan; Chen, Jie; Fang, Yun; Zhu, Meng

    2016-10-01

    Accordance with the previously supposed polyelectrolyte-like behaviour of neutral polymer-anionic surfactant complexes, direct evidence for the formation of the pseudo-polyanions in polyvinylpyrrolidone (PVP)-sodium dodecylsulfate (SDS) solution is put forward in this paper by capillary electrophoresis (CE) experiments in assistance with capillary viscosimetry and conductometry. The contradictory phenomena of the absolute value of relative electrophoretic mobility (re) increasing while the ionization degree (α) decreasing with the increasing specific clusterization [Г] in aqueous PVP-SDS solution are explained by the finding that the PVP-SDS complex is eventually a family of PVP-SDS pseudo-polyanions with different charge densities. And it is found countercations playing an important role in the formation of the PVP-SDS pseudo-polyanions in virtue of bridge effect. PMID:27348481

  5. Facile solvothermal synthesis of abnormal growth of one-dimensional ZnO nanostructures by ring-opening reaction of polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Xu, G.; Wang, X. L.; Liu, G. Z.

    2015-02-01

    Abnormal growth of one-dimensional (1-D) ZnO nanostructures (NSs) have been accomplished with the assistance of polyvinylpyrrolidone (PVP) under a super high alkaline alcoholic solvothermal condition. The products were characterized by transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The effect of synthetic conditions, such as reaction temperature and the addition of PVP, on the morphologies of ZnO products were investigated. The results show that PVP molecules had the significant role in the transformation of morphologies of ZnO NSs ranging from nanorods, nanoparticles to pyramids, as well as flower-like assembly features. The possible growth mechanism of ZnO pyramids was proposed based on ring-opening reaction of PVP.

  6. ANALYSIS OF TOTAL RESPIRATORY DEPOSITION OF INHALED ULTRAFINE PARTICLES IN ADULT SUBJECTS AT VARIOUS BREATHING PATTERNS

    EPA Science Inventory

    Ultrafine particles are ubiquitous in the ambient air and their unique physicochemical characteristics may pose a potential health hazard. Accurate lung dose information is essential to assess a potential health risk to exposure to these particles. In the present study, we measur...

  7. Suppression of methane/air explosion by ultrafine water mist containing sodium chloride additive.

    PubMed

    Cao, Xingyan; Ren, Jingjie; Zhou, Yihui; Wang, Qiuju; Gao, Xuliang; Bi, Mingshu

    2015-03-21

    The suppression effect of ultrafine mists on methane/air explosions with methane concentrations of 6.5%, 8%, 9.5%, 11%, and 13.5% were experimentally studied in a closed visual vessel. Ultrafine water/NaCl solution mist as well as pure water mist was adopted and the droplet sizes of mists were measured by phase doppler particle analyzer (PDPA). A high speed camera was used to record the flame evolution processes. In contrast to pure water mist, the flame propagation speed, the maximum explosion overpressure (ΔP(max)), and the maximum pressure rising rate ((dP/dt)max) decreased significantly, with the "tulip" flame disappearing and the flame getting brighter. The results show that the suppressing effect on methane explosion by ultrafine water/NaCl solution mist is influenced by the mist amount and methane concentration. With the increase of the mist amount, the pressure, and the flame speed both descended significantly. And when the mist amount reached 74.08 g/m(3) and 37.04 g/m(3), the flames of 6.5% and 13.5% methane explosions can be absolutely suppressed, respectively. All of results indicate that addition of NaCl can improve the suppression effect of ultrafine pure water mist on the methane explosions, and the suppression effect is considered due to the combination effect of physical and chemical inhibitions. PMID:25528229

  8. MECHANISMS BY WHICH ULTRAFINE, FINE, AND COARSE PARTICLES CAUSE ADVERSE HEALTH EFFECTS

    EPA Science Inventory

    A small number of recent studies suggest that different size particles may cause different health effects. There are clearly differences in the chemical makeup of coarse, fine, and ultrafine particles, and this different chemistry may well drive different health responses. The ...

  9. TRANSLOCATION AND POTENTIAL NEUROLOGICAL EFFECTS OF FINE AND ULTRAFINE PARTICLES: A CRITICAL UPDATE

    EPA Science Inventory

    This proceedings book is a collection of seminars presented in a symposium organized by by Munich's GSF-National Research Center for Environment and Health. Research presented at this symposium indicated inhaled ultrafine particulate matter quickly exits the lungs and target...

  10. Microstructure and Deformation Behavior of Phase-Reversion-Induced Nanograined/Ultrafine-Grained Austenitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Misra, R. D. K.; Nayak, S.; Mali, S. A.; Shah, J. S.; Somani, M. C.; Karjalainen, L. P.

    2009-10-01

    Materials with submicron to nanometer-sized grains by virtue of their high grain boundary area to grain size ratio provide valuable tools for studying deformation behavior in ultrafine-grained structures. In this regard, the well-known strain-induced martensite transformation and its reversal to the parent austenite phase were used to produce nanograins/ultrafine grains via controlled annealing of heavily cold-worked metastable austenite. The results of the electron microscopy study of phase-reversion-induced microstructure and deformation behavior of nanograined/ultrafine-grained (NG/UFG) austenitic stainless steel during tensile straining are described here. The phase-reversion-induced structure was observed to depend on the cold rolling reduction and temperature-time annealing cycle. The optimized structure consisted of nanocrystalline ( d < 100 nm), ultrafine ( d ≈ 100 to 500 nm), and submicron ( d ≈ 500 to 1000 nm) grains and was characterized by a high yield strength (800 to 1000 MPa)-high ductility (30 to 40 pct) combination. Austenite nucleation during phase-reversion annealing occurred in the form of thin plates or as equiaxed grains along the martensite laths. Twinning and dislocation glide were identified as the primary deformation mechanisms, where twinning had a varied character. However, the high elongation seems to be associated with the gradual transformation of metastable austenite, with twinning having only a minor contribution.

  11. Controlled Exposure of Humans with Metabolic Syndrome to Concentrated Ultrafine Ambient Particulate Matter Causes Cardiovascular Effects

    EPA Science Inventory

    Background: Many studies have reported associations between PM2.5 and adverse cardiovascular effects. However there is increased concern that ultrafine PM (aerodynamic diameter less than 0.1 micron) may be disproportionately toxic relative to the 0.1 to 2.5 micron fraction of PM2...

  12. Method for producing ultrafine-grained materials using repetitive corrugation and straightening

    DOEpatents

    Zhu, Yuntian T.; Lowe, Terry C.; Jiang, Honggang; Huang, Jianyu

    2001-01-01

    A method of refining the grain structure and improving the hardness and strength properties of a metal or metal alloy workpiece is disclosed. The workpiece is subjected to forces that corrugate and then straighten the workpiece. These steps are repeated until an ultrafine-grained product having improved hardness and strength is produced.

  13. SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES

    EPA Science Inventory

    SIGNALING MECHANISMS IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES
    Y.M. Kim, A.G. Lenz, R. Silbajoris, I. Jaspers and J.M. Samet. Department of Environmental Sciences and Engineering and Center for Environmental Medicine, University of North Carolina, ...

  14. DEPOSITION DISTRIBUTION OF NANO AND ULTRAFINE PARTICLES IN HUMAN LUNGS DURING CONTROLLED MOUTH BREATHING

    EPA Science Inventory

    Nano and ultrafine particles are abundant in the atmosphere and the level of human exposure to these tiny particles is expected to increase markedly as industrial activities increase manufacturing nano-sized materials. Exposure-dose relationships and site-specific internal dose a...

  15. The Effects of Vegetation Barriers on Near-road Ultrafine Particle Number and Carbon Monoxide Concentrations

    EPA Science Inventory

    Numerous studies have shown that people living in near-roadway communities (within 100 m of the road) are exposed to high ultrafine particle (UFP) number concentrations, which may be associated with adverse health effects. Vegetation barriers have been shown to affect pollutant t...

  16. PULMONARY AND CARDIAC GENE EXPRESSION FOLLOWING ACUTE ULTRAFINE CARBON PARTICLE INHALATION IN HYPERTENSIVE RATS

    EPA Science Inventory

    Inhalation of ultrafine carbon particles (ufCP) causes cardiac physiological changes without marked pulmonary injury or inflammation. We hypothesized that acute ufCP exposure of 13 months old Spontaneously Hypertensive (SH) rats will cause differential effects on the lung and hea...

  17. ENHANCED TOXICITY OF CHARGED CARBON NANOTUBES AND ULTRAFINE CARBON BLACK PARTICLES

    EPA Science Inventory

    Man-made carbonaceous nano-particles such as single and multi-walled carbon nano-tubes (CNT) and ultra-fine carbon black (UFCB) particles are finding increasing applications in industry, but their potential toxic effects is of concern. In aqueous media, these particles cluster in...

  18. The exposure to coarse, fine and ultrafine particle emissions from concrete mixing, drilling and cutting activities.

    PubMed

    Azarmi, Farhad; Kumar, Prashant; Mulheron, Mike

    2014-08-30

    Building activities generate coarse (PM10≤10μm), fine (PM2.5≤2.5μm) and ultrafine particles (<100nm) making it necessary to understand both the exposure levels of operatives on site and the dispersion of ultrafine particles into the surrounding environment. This study investigates the release of particulate matter, including ultrafine particles, during the mixing of fresh concrete (incorporating Portland cement with Ground Granulated Blastfurnace Slag, GGBS or Pulverised Fuel Ash, PFA) and the subsequent drilling and cutting of hardened concrete. Particles were measured in the 5-10,000nm size range using a GRIMM particle spectrometer and a fast response differential mobility spectrometer (DMS50). The mass concentrations of PM2.5-10 fraction contributed ∼52-64% of total mass released. The ultrafine particles dominated the total particle number concentrations (PNCs); being 74, 82, 95 and 97% for mixing with GGBS, mixing with PFA, drilling and cutting, respectively. Peak values measured during the drilling and cutting activities were 4 and 14 times the background. Equivalent emission factors were calculated and the total respiratory deposition dose rates for PNCs for drilling and cutting were 32.97±9.41×10(8)min(-1) and 88.25±58.82×10(8)min(-1). These are a step towards establishing number and mass emission inventories for particle exposure during construction activities. PMID:25068443

  19. Seasonal variability of ultra-fine metals downwind of a heavily traveled secondary road

    NASA Astrophysics Data System (ADS)

    Cahill, Thomas A.; Barnes, David E.; Spada, Nicholas J.

    2014-09-01

    Since 2002, we have been studying the impact of a heavily traveled secondary road on an adjacent downwind school located at a stop light controlled intersection. The prior studies were all performed in winter conditions with typically strong inversions, but established significant PM2.5 impacts on the school roughly in accord with theoretical models and the relevant literature. In this project, we have enhanced this effort by extending the study from winter to summer, and adding compositionally-resolved ultra-fine aerosol measurements. Ultra-fine aerosols, including metals derived from both brake wear and zinc in lubricating oil, were present at high concentrations in winter downwind of the roadway but absent at a residential site 500 m upwind. Their concentrations faded to minor levels in spring and early summer, while coarse roadway resuspended dust increased in that period. A comparison of ultra-fine measurements in downtown Sacramento and other California Central Valley sites indicates that these traffic derived aerosols are widely present in urban areas impacted by heavy traffic, freeways and secondary streets, especially where heavy braking is occurring. The potential for health impacts of ultra-fine metals associated with cars braking and accelerating in inversion conditions is a serious health concern based on recent epidemiological studies.

  20. OXIDATIVE STRESS AND LIPID MEDIATORS INDUCED IN ALVEOLAR MACHROPHAGES BY ULTRAFINE PARTICLES

    EPA Science Inventory

    In ambient aerosols, ultrafine particles (UFP) and their agglomerates are considered to be major factors contributing to adverse health effects. Reactivity of agglomerated UFP of elemental carbon (EC), Printex 90, Printex G, and diesel exhaust particles (DEP) was evaluated by the...

  1. UP-REGULATION OF TISSUE FACTOR IN HUMAN PULMONARY ARTERY ENDOTHELIAL CELLS AFTER ULTRAFINE PARTICLE EXPOSURE

    EPA Science Inventory

    Background: Epidemiology studies have linked exposure to pollutant particles to

    increased cardiovascular mortality and morbidity, but the mechanisms remain unknown.

    Objectives: We tested the hypothesis that the ultrafine fraction of ambient pollutant

    particle...

  2. CARDIOVASCULAR RESPONSES IN UNRESTRAINED WKY-RATS TO INHALED ULTRAFINE CARBON PARTICLES

    EPA Science Inventory

    Abstract
    This study provides evidence for adverse cardiac effects of inhaled ultrafine particles (UFPs) in healthy WKY rats. Short term exposure (24 h) with carbon UFPs (180 ?g?m ?) induced a moderate but significant heart rate increase of 18 bpm (4.8 %) in association with a ...

  3. Combustion of PTFE: The effects of gravity on ultrafine particle generation

    NASA Technical Reports Server (NTRS)

    McKinnon, Thomas; Todd, Paul; Oberdorster, Gunter

    1996-01-01

    The objective of this project is to obtain an understanding of the effect of gravity on the toxicity of ultrafine particle and gas phase materials produced when fluorocarbon polymers are thermally degraded or burned. The motivation for the project is to provide a basic technical foundation on which policies for spacecraft health and safety with regard to fire and polymers can be formulated.

  4. DESIGN AND CHARACTERIZATION OF AN ULTRAFINE COAL ASH AEROSOL GENERATOR FOR DIRECT ANIMAL EXPOSURE STUDIES

    EPA Science Inventory

    Primary ultrafine particulate matter (PM) is produced during pulverized coal combustion by the nucleation and heterogeneous condensation of vapor-phase species. This differs from the mechanisms that control the formation of the supermicron fly ash that is heavily influenced by t...

  5. Ultrafine and respirable particle exposure during vehicle fire suppression

    PubMed Central

    Fent, Kenneth W.

    2015-01-01

    Vehicle fires are a common occurrence, yet few studies have reported exposures associated with burning vehicles. This article presents an assessment of firefighters’ potential for ultrafine and respirable particle exposure during vehicle fire suppression training. Fires were initiated within the engine compartment and passenger cabins of three salvaged vehicles, with subsequent water suppression by fire crews. Firefighter exposures were monitored with an array of direct reading particle and air quality instruments. A flexible metallic duct and blower drew contaminants to the instrument array, positioned at a safe distance from the burning vehicles, with the duct inlet positioned at the nozzle operator’s shoulder. The instruments measured the particle number, active surface area, respirable particle mass, photoelectric response, aerodynamic particle size distributions, and air quality parameters. Although vehicle fires were suppressed quickly (<10 minutes), firefighters may be exposed to short duration, high particle concentration episodes during fire suppression, which are orders of magnitude greater than the ambient background concentration. A maximum transient particle concentration of 1.21 × 107 particles per cm3, 170 mg m−3 respirable particle mass, 4700 μm2 cm−3 active surface area and 1400 (arbitrary units) in photoelectric response were attained throughout the series of six fires. Expressed as fifteen minute time-weighted averages, engine compartment fires averaged 5.4 × 104 particles per cm3, 0.36 mg m−3 respirable particle mass, 92 μm2 cm−3 active particle surface area and 29 (arbitrary units) in photoelectric response. Similarly, passenger cabin fires averaged 2.04 × 105 particles per cm3, 2.7 mg m−3 respirable particle mass, 320 μm2 cm−3 active particle surface area, and 34 (arbitrary units) in photoelectric response. Passenger cabin fires were a greater potential source of exposure than engine compartment fires. The wind direction

  6. Novel ultrafine grain size processing of soft magnetic materials.

    SciTech Connect

    Michael, Joseph Richard; Robino, Charles Victor

    2009-01-01

    High performance soft magnetic alloys are used in solenoids in a wide variety of applications. These designs are currently being driven to provide more margin, reliability, and functionality through component size reductions; thereby providing greater power to drive ratio margins as well as decreases in volume and power requirements. In an effort to produce soft magnetic materials with improved properties, we have conducted an initial examination of one potential route for producing ultrafine grain sizes in the 49Fe-49Co-2V alloy. The approach was based on a known method for the production of very fine grain sizes in steels, and consisted of repeated, rapid phase transformation cycling through the ferrite to austenite transformation temperature range. The results of this initial attempt to produce highly refined grain sizes in 49Fe-49Co-2V were successful in that appreciable reductions in grain size were realized. The as-received grain size was 15 {micro}m with a standard deviation of 9.5 {micro}m. For the temperature cycling conditions examined, grain refinement appears to saturate after approximately ten cycles at a grain size of 6 {micro}m with standard deviation of 4 {micro}m. The process also reduces the range of grain sizes present in these samples as the largest grain noted in the as received and treated conditions were 64 and 26 {micro}m, respectively. The results were, however, complicated by the formation of an unexpected secondary ferritic constituent and considerable effort was directed at characterizing this phase. The analysis indicates that the phase is a V-rich ferrite, known as {alpha}{sub 2}, that forms due to an imbalance in the partitioning of vanadium during the heating and cooling portions of the thermal cycle. Considerable but unsuccessful effort was also directed at understanding the conditions under which this phase forms, since it is conceivable that this phase restricts the degree to which the grains can be refined. Due to this difficulty

  7. Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles.

    PubMed

    Oberdörster, Günter; Oberdörster, Eva; Oberdörster, Jan

    2005-07-01

    Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older biokinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need

  8. Ultrafine and respirable particle exposure during vehicle fire suppression.

    PubMed

    Evans, Douglas E; Fent, Kenneth W

    2015-10-01

    Vehicle fires are a common occurrence, yet few studies have reported exposures associated with burning vehicles. This article presents an assessment of firefighters' potential for ultrafine and respirable particle exposure during vehicle fire suppression training. Fires were initiated within the engine compartment and passenger cabins of three salvaged vehicles, with subsequent water suppression by fire crews. Firefighter exposures were monitored with an array of direct reading particle and air quality instruments. A flexible metallic duct and blower drew contaminants to the instrument array, positioned at a safe distance from the burning vehicles, with the duct inlet positioned at the nozzle operator's shoulder. The instruments measured the particle number, active surface area, respirable particle mass, photoelectric response, aerodynamic particle size distributions, and air quality parameters. Although vehicle fires were suppressed quickly (<10 minutes), firefighters may be exposed to short duration, high particle concentration episodes during fire suppression, which are orders of magnitude greater than the ambient background concentration. A maximum transient particle concentration of 1.21 × 10(7) particles per cm(3), 170 mg m(-3) respirable particle mass, 4700 μm(2) cm(-3) active surface area and 1400 (arbitrary units) in photoelectric response were attained throughout the series of six fires. Expressed as fifteen minute time-weighted averages, engine compartment fires averaged 5.4 × 10(4) particles per cm(3), 0.36 mg m(-3) respirable particle mass, 92 μm(2) cm(-3) active particle surface area and 29 (arbitrary units) in photoelectric response. Similarly, passenger cabin fires averaged 2.04 × 10(5) particles per cm(3), 2.7 mg m(-3) respirable particle mass, 320 μm(2) cm(-3) active particle surface area, and 34 (arbitrary units) in photoelectric response. Passenger cabin fires were a greater potential source of exposure than engine compartment fires. The

  9. Nature and evolution of ultrafine aerosol particles in the atmosphere

    NASA Astrophysics Data System (ADS)

    Smirnov, V. V.

    2006-12-01

    Results of experimental and theoretical studies of a poorly understood phenomenon, an intense emission of ultrafine (nanometer) aerosols (ENA), are reviewed. In the English-language literature, this phenomenon is commonly referred to as a nucleation burst. ENA events have been observed on all the continents and throughout the depth of the troposphere, with the number of corresponding publications growing steadily. Intense and long-lasting ENA events have been studied more or less comprehensively and in full detail for Northern Europe, with 60 to 70% of observations taken in a forest area in the presence of snow cover and 10 to 20% in coastal marine areas. Most often, ENA events occur during spring and fall, with 95% of cases in the daytime and under sunny calm conditions, typical of anticyclones. In ENA events, the concentration of nanoparticles initially grows rapidly to values of 103-105 cm-3. One or two hours later, the so-called nuclei fraction with diameters D = 3-15 nm is produced. The appearance of the Aitken fraction D = 20-80 nm and the enlargement of aerosol particles inside the accumulation fraction D = 80-200 nm may occur during the following 4-6 h. Thus, the cycle of formation and growth of atmospheric aerosol particles in the size range from a few to hundreds of nanometers is reproduced over 6-8 h. A specific synoptic feature of ENA events over land is that they occur when the polar air is transported to measuring sites and the temperature difference between day and light is large. During ENA periods, the formation rate of condensation nuclei with a diameter of 100 nm increases 10-to 100-fold. Important factors of ENA genesis are the “aerosol” and “electric” states of the atmosphere. More intense ENA events occur at low concentrations of background aerosols in the presence of atmospheric ions of medium mobility with D = 2-3 nm. The international experiments ACE 1 and 2, BIOFOR 1, 2, and 3, ESUP 2000, QUEST, etc., have not yet provided any

  10. Nanotoxicology: An Emerging Discipline Evolving from Studies of Ultrafine Particles

    PubMed Central

    Oberdörster, Günter; Oberdörster, Eva; Oberdörster, Jan

    2005-01-01

    Although humans have been exposed to airborne nanosized particles (NSPs; < 100 nm) throughout their evolutionary stages, such exposure has increased dramatically over the last century due to anthropogenic sources. The rapidly developing field of nanotechnology is likely to become yet another source through inhalation, ingestion, skin uptake, and injection of engineered nanomaterials. Information about safety and potential hazards is urgently needed. Results of older bio-kinetic studies with NSPs and newer epidemiologic and toxicologic studies with airborne ultrafine particles can be viewed as the basis for the expanding field of nanotoxicology, which can be defined as safety evaluation of engineered nanostructures and nanodevices. Collectively, some emerging concepts of nanotoxicology can be identified from the results of these studies. When inhaled, specific sizes of NSPs are efficiently deposited by diffusional mechanisms in all regions of the respiratory tract. The small size facilitates uptake into cells and transcytosis across epithelial and endothelial cells into the blood and lymph circulation to reach potentially sensitive target sites such as bone marrow, lymph nodes, spleen, and heart. Access to the central nervous system and ganglia via translocation along axons and dendrites of neurons has also been observed. NSPs penetrating the skin distribute via uptake into lymphatic channels. Endocytosis and biokinetics are largely dependent on NSP surface chemistry (coating) and in vivo surface modifications. The greater surface area per mass compared with larger-sized particles of the same chemistry renders NSPs more active biologically. This activity includes a potential for inflammatory and pro-oxidant, but also antioxidant, activity, which can explain early findings showing mixed results in terms of toxicity of NSPs to environmentally relevant species. Evidence of mitochondrial distribution and oxidative stress response after NSP endocytosis points to a need

  11. Residential infiltration of fine and ultrafine particles in Edmonton

    NASA Astrophysics Data System (ADS)

    Kearney, Jill; Wallace, Lance; MacNeill, Morgan; Héroux, Marie-Eve; Kindzierski, Warren; Wheeler, Amanda

    2014-09-01

    Airborne indoor particles arise from both indoor sources and ambient particles that have infiltrated indoors. The intra-urban variability of infiltration factors (Finf) is a source of measurement error in epidemiological studies estimating exposure from a central site measurement, hence information on the within and between-home variability of Finf is useful to better characterize ambient PM exposure. The objective of this paper was to estimate magnitudes and predictors of daily residential infiltration factors (Finf) and ambient/non-ambient components of indoor ultrafine particle (UFP) and fine particle (FP) concentrations. FPs and UFPs were measured continuously for 7 consecutive days in 74 Edmonton homes in winter and summer 2010 (50 homes in each season). Simultaneous measurements of outdoor (near-home) FP and ambient (at a central site) UFP concentrations were also measured. Daily infiltration factors were estimated for each home; considerable variability was seen within and between homes. For FPs, seasonal-averaged Finf (the average of the 7 daily Finf estimates) ranged from 0.10 to 0.92 in winter (median = 0.30, n = 49) and 0.31 to 0.99 in summer (median = 0.68, n = 48). For UFPs, the seasonal-averaged Finf ranged from 0.08 to 0.47 across homes in winter (median = 0.21, n = 33 houses) and from 0.16 to 0.94 in summer (median = 0.57, n = 48). The higher median Finf in summer was attributed to a high frequency of open windows. Daily infiltration factors were also estimated based on the indoor/outdoor PM1 sulfur ratio. These estimates were poorly correlated with DustTrak-based FP infiltration factor estimates; the difference may be due to losses of volatile components on the PM1 filter samples. Generalized linear mixed models were used to identify variables significantly associated with Finf and the non-ambient component of indoor FP and UFP concentrations. Wind speed was consistently associated with Finf across all seasons for both FPs and UFPs. The use of an

  12. Association of particulate air pollution and acute mortality: involvement of ultrafine particles?

    NASA Technical Reports Server (NTRS)

    Oberdorster, G.; Gelein, R. M.; Ferin, J.; Weiss, B.; Clarkson, T. W. (Principal Investigator)

    1995-01-01

    Recent epidemiological studies show an association between particulate air pollution and acute mortality and morbidity down to ambient particle concentrations below 100 micrograms/m3. Whether this association also implies a causality between acute health effects and particle exposure at these low levels is unclear at this time; no mechanism is known that would explain such dramatic effects of low ambient particle concentrations. Based on results of our past and most recent inhalation studies with ultrafine particles in rats, we propose that such particles, that is, particles below approximately 50 nm in diameter, may contribute to the observed increased mortality and morbidity In the past we demonstrated that inhalation of highly insoluble particles of low intrinsic toxicity, such as TiO2, results in significantly increased pulmonary inflammatory responses when their size is in the ultrafine particle range, approximately 20 nm in diameter. However, these effects were not of an acute nature and occurred only after prolonged inhalation exposure of the aggregated ultrafine particles at concentrations in the milligrams per cubic meter range. In contrast, in the course of our most recent studies with thermodegradation products of polytetrafluoroethylene (PTFE) we found that freshly generated PTFE fumes containing singlet ultrafine particles (median diameter 26 nm) were highly toxic to rats at inhaled concentrations of 0.7-1.0 x 10(6) particles/cm3, resulting in acute hemorrhagic pulmonary inflammation and death after 10-30 min of exposure. We also found that work performance of the rats in a running wheel was severely affected by PTFE fume exposure. These results confirm reports from other laboratories of the highly toxic nature of PTFE fumes, which cannot be attributed to gas-phase components of these fumes such as HF, carbonylfluoride, or perfluoroisobutylene, or to reactive radicals. The calculated mass concentration of the inhaled ultrafine PTFE particles in our

  13. Simultaneous Grain Growth and Grain Refinement in Bulk Ultrafine-Grained Copper under Tensile Deformation at Room Temperature

    NASA Astrophysics Data System (ADS)

    Yu, Hailiang; Lu, Cheng; Tieu, Anh Kiet; Li, Huijun; Godbole, Ajit; Kong, Charlie; Zhao, Xing

    2016-08-01

    Grain growth and grain refinement behavior during deformation determine the strength and ductility of ultrafine-grained materials. We used asymmetric cryorolling to fabricate ultrafine-grained copper sheets with an average grain width of 230 nm and having a laminate structure. The sheets show a high-true failure strain of 1.5. Observation of the microstructure at the fracture surface reveals that ultrafine laminate-structured grains were simultaneously transformed into both equiaxed nanograins and coarse grains under tensile deformation at room temperature.

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

    SciTech Connect

    Not Available

    1992-05-01

    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 focused on assembling the supercritical particle generation/collection system. Effort was applied to constructing a shakedown testing plan also.

  15. Antimicrobial activity of electrospun poly(butylenes succinate) fiber mats containing PVP-capped silver nanoparticles.

    PubMed

    Tian, Ligang; Wang, Pingli; Zhao, Zhiguo; Ji, Junhui

    2013-12-01

    In this study, biodegradable poly(butylenes succinate) (PBS) fiber mats containing silver nanoparticles (AgNPs) were prepared by the electrospinning process. Small AgNPs (<10 nm) were simply synthesized using polyvinylpyrrolidone as the capping agent as well as the reductant. The morphology of the PBS-AgNPs fiber mats and the distribution of the AgNPs were well characterized by TEM and SEM. The release of Ag from the PBS fiber mats was quantitively determined by ICP. The PBS fiber mats with 0.29 % AgNPs content showed strong antimicrobial activity against both gram-positive Staphylococcus aureus and gram-negative Escherichia coli with the efficacy as high as 99 %. The effective bactericidal activity on E. coli was demonstrated for a short contacting time with the PBS-AgNPs fiber mats. In addition, the long-term release performance of Ag from the fiber mats can keep inhibiting the bacterial growth in the mats over a long period of time. PMID:24013858

  16. Processing, mechanical behavior and biocompatibility of ultrafine grained zirconium fabricated by accumulative roll bonding

    NASA Astrophysics Data System (ADS)

    Jiang, Ling

    The aim of this study is to produce large quantities of bulk zirconium with an ultrafine grained microstructure and with enhanced properties. Accumulative roll bonding (ARB), a severe plastic deformation technique based on rolling, is chosen due to its availability in industrial environment. The texture, microstructure and mechanical behavior of bulk ultrafine grained (ufg) Zr fabricated by accumulative roll bonding is investigated by electron backscatter diffraction, transmission electron microscopy and mechanical testing. A reasonably homogeneous and equiaxed ufg structure, with a large fraction of high angle boundaries (HABs, ˜70%), can be obtained in Zr after only two ARB cycles. The average grain size, counting only HABs (theta>15°), is 400 nm. (Sub)grain size is equal to 320 nm. The yield stress and ultimate tensile stress (UTS) values are nearly double those from conventionally processed Zr with only a slight loss of ductility. Optimum processing conditions include large thickness reductions per pass (˜75%), which enhance grain refinement, and a rolling temperature (T ˜ 0.3Tm) at which a sufficient number of slip modes are activated, with an absence of significant grain growth. Grain refinement takes place by geometrical thinning and grain subdivision by the formation of geometrically necessary boundaries. The formation of equiaxed grains by geometric dynamic recrystallization is facilitated by enhanced diffusion due to adabatic heating. Optical microscopy examination and shear testing suggest accepted bonding quality compared to that achieved in materials processed by diffusion bonding and that obtained in other ARB studies. Biocompatibility of ultrafine grained Zr processed by large strain rolling is studied by evaluating the behavior of human osteoblast cells. It is suggested that ultrafine grained Zr has a similar good biocompatibility as Ti6Al4V alloy and conventional Zr with a large grain size have. The improved mechanical properties together with

  17. Microstructure of warm rolling and pearlitic transformation of ultrafine-grained GCr15 steel

    SciTech Connect

    Sun, Jun-Jie; Lian, Fu-Liang; Liu, Hong-Ji; Jiang, Tao; Guo, Sheng-Wu; Du, Lin-Xiu; Liu, Yong-Ning

    2014-09-15

    Pearlitic transformation mechanisms have been investigated in ultra-fine grained GCr15 steel. The ultrafine-grained steel, whose grain size was less than 1 μm, was prepared by thermo-mechanical treatment at 873 K and then annealing at 923 K for 2 h. Pearlitic transformation was conducted by reheating the ultra-fine grained samples at 1073 K and 1123 K for different periods of time and then cooling in air. Scanning electron microscope observation shows that normal lamellar pearlite, instead of granular cementite and ferrite, cannot be formed when the grain size is approximately less than 4(± 0.6) μm, which yields a critical grain size for normal lamellar pearlitic transformations in this chromium alloyed steel. The result confirms that grain size has a great influence on pearlitic transformation by increasing the diffusion rate of carbon atoms in the ultra-fine grained steel, and the addition of chromium element doesn't change this pearlitic phase transformation rule. Meanwhile, the grain growth rate is reduced by chromium alloying, which is beneficial to form fine grains during austenitizing, thus it facilitating pearlitic transformation by divorced eutectoid transformation. Moreover, chromium element can form a relatively high gradient in the frontier of the undissolved carbide, which promotes carbide formation in the frontier of the undissolved carbide, i.e., chromium promotes divorced eutectoid transformation. - Highlights: • Ultrafine-grained GCr15 steel was obtained by warm rolling and annealing technology. • Reduction of grain size makes pearlite morphology from lamellar to granular. • Adding Cr does not change normal pearlitic phase transformation rule in UFG steel. • Cr carbide resists grain growth and facilitates pearlitic transformation by DET.

  18. Relationship of pulmonary toxicity and carcinogenicity of fine and ultrafine granular dusts in a rat bioassay.

    PubMed

    Kolling, Angelika; Ernst, Heinrich; Rittinghausen, Susanne; Heinrich, Uwe

    2011-08-01

    The current carcinogenicity study with female rats focused on the toxicity and carcinogenicity of intratracheally instilled fine and ultrafine granular dusts. The positive control, crystalline silica, elicited the greatest magnitude and progression of pulmonary inflammatory reactions, fibrosis and the highest incidence of primary lung tumors (39.6%). Addition of poly-2-vinylpyridine-N-oxide decreased inflammatory responses, fibrosis, and the incidence of pulmonary tumors induced by crystalline quartz to 21.4%. After repeated instillation of soluble, ultrafine amorphous silica (15 mg) a statistically significant tumor response (9.4%) was observed, although, the inflammatory response in the lung was not as persistently severe as in rats treated with carbon black. Instillation of ultrafine carbon black (5 mg) caused a lung tumor incidence of 15%. In contrast to a preceding study using a dose of 66 mg coal dust, lung tumors were not detected after exposure to the same coal dust at a dose of 10 mg in this study. Pulmonary inflammatory responses to coal dust were very low indicating a mechanistic threshold for the development of lung tumors connected with particle related chronic inflammation. The animals treated with ultrafine carbon black and ultrafine amorphous silica showed significantly more severe lesions in non-cancerous endpoints when compared to animals treated with fine coal dust. Furthermore, carbon black treated rats showed more severe non-cancerous lung lesions than amorphous silica treated rats. Our data show a relationship between tumor frequencies and increasing scores when using a qualitative scoring system for specific non-cancerous endpoints such as inflammation, fibrosis, epithelial hyperplasia, and squamous metaplasia. PMID:21819261

  19. Relationship of pulmonary toxicity and carcinogenicity of fine and ultrafine granular dusts in a rat bioassay

    PubMed Central

    Kolling, Angelika; Ernst, Heinrich; Rittinghausen, Susanne; Heinrich, Uwe

    2011-01-01

    The current carcinogenicity study with female rats focused on the toxicity and carcinogenicity of intratracheally instilled fine and ultrafine granular dusts. The positive control, crystalline silica, elicited the greatest magnitude and progression of pulmonary inflammatory reactions, fibrosis and the highest incidence of primary lung tumors (39.6%). Addition of poly-2-vinylpyridine-N-oxide decreased inflammatory responses, fibrosis, and the incidence of pulmonary tumors induced by crystalline quartz to 21.4%. After repeated instillation of soluble, ultrafine amorphous silica (15 mg) a statistically significant tumor response (9.4%) was observed, although, the inflammatory response in the lung was not as persistently severe as in rats treated with carbon black. Instillation of ultrafine carbon black (5 mg) caused a lung tumor incidence of 15%. In contrast to a preceding study using a dose of 66 mg coal dust, lung tumors were not detected after exposure to the same coal dust at a dose of 10 mg in this study. Pulmonary inflammatory responses to coal dust were very low indicating a mechanistic threshold for the development of lung tumors connected with particle related chronic inflammation. The animals treated with ultrafine carbon black and ultrafine amorphous silica showed significantly more severe lesions in non-cancerous endpoints when compared to animals treated with fine coal dust. Furthermore, carbon black treated rats showed more severe non-cancerous lung lesions than amorphous silica treated rats. Our data show a relationship between tumor frequencies and increasing scores when using a qualitative scoring system for specific non-cancerous endpoints such as inflammation, fibrosis, epithelial hyperplasia, and squamous metaplasia. PMID:21819261

  20. Photovoltaic fibers

    NASA Astrophysics Data System (ADS)

    Gaudiana, Russell; Eckert, Robert; Cardone, John; Ryan, James; Montello, Alan

    2006-08-01

    It was realized early in the history of Konarka that the ability to produce fibers that generate power from solar energy could be applied to a wide variety of applications where fabrics are utilized currently. These applications include personal items such as jackets, shirts and hats, to architectural uses such as awnings, tents, large covers for cars, trucks and even doomed stadiums, to indoor furnishings such as window blinds, shades and drapes. They may also be used as small fabric patches or fiber bundles for powering or recharging batteries in small sensors. Power generating fabrics for clothing is of particular interest to the military where they would be used in uniforms and body armor where portable power is vital to field operations. In strong sunlight these power generating fabrics could be used as a primary source of energy, or they can be used in either direct sunlight or low light conditions to recharge batteries. Early in 2002, Konarka performed a series of proof-of-concept experiments to demonstrate the feasibility of building a photovoltaic cell using dye-sensitized titania and electrolyte on a metal wire core. The approach taken was based on the sequential coating processes used in making fiber optics, namely, a fiber core, e.g., a metal wire serving as the primary electrode, is passed through a series of vertically aligned coating cups. Each of the cups contains a coating fluid that has a specific function in the photocell. A second wire, used as the counter electrode, is brought into the process prior to entering the final coating cup. The latter contains a photopolymerizable, transparent cladding which hardens when passed through a UV chamber. Upon exiting the UV chamber, the finished PV fiber is spooled. Two hundred of foot lengths of PV fiber have been made using this process. When the fiber is exposed to visible radiation, it generates electrical power. The best efficiency exhibited by these fibers is 6% with an average value in the 4

  1. Ultrafine particulate matter exposure in vitro impairs vasorelaxant response in superoxide dismutase 2 deficient and aged murine aortic rings

    EPA Science Inventory

    Epidemiological studies positively associate exposure to inhaled ultrafine particulate matter (UFPM) and adverse cardiovascular events. PM-induced oxidative stress is believed to be a key mechanism contributing to the adverse short-term vascular effects of air pollution exposure....

  2. ULTRAFINE CARBON PARTICLES INDUCE INTERLEUKIN-8 GENE TRANSCRIPTION AND P38 MAPK ACTIVATION IN NORMAL BRONCHIAL EPITHELIAL CELLS

    EPA Science Inventory

    Epidemiological studies suggest that ultrafine particles contribute to particulate matter-induced adverse health effects. Interleukin (IL)-8 is an important proinflammatory cytokine in the human lung that is induced in respiratory cells exposed to a variety of environmental insul...

  3. Exposure for ultrafine carbon particles at levels below detectable pulmonary inflammation affects cardiovascular performance in spontaneously hypertensive rats*

    EPA Science Inventory

    Rationale: Exposure to particulate matter is a risk factor for cardiopulmonary disease but the related molecular mechanisms are poorly understood. Previously we studied cardiovascular responses in healthy WKY rats following inhalation exposure to ultrafine carbon particles (UfCPs...

  4. Long-term assessment of ultrafine particles on major roadways in Las Vegas, Nevada and Detroit, Michigan

    EPA Science Inventory

    This is a presentation at the National Air Monitoring conference, given at the request of OAQPS partners. The presentation will cover ultrafine particle data collected at three locations - Las Vegas, Detroit, and Research Triangle Park.

  5. Fiber crops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Much research continues to develop renewable, recyclable, sustainable, and bio-based products from agricultural feed stocks such as cotton and flax fiber. Primary requirements are sustainable production, low cost, and consistent and known quality. To better understand these products, research contin...

  6. Low-temperature densification of ultrafine grained aluminum 6061-T6 by polymer bonding

    NASA Astrophysics Data System (ADS)

    Kim, Boumseock

    Ultrafine grained and nanocrytalline materials have many beneficial properties such as higher hardness, strength and wear resistance. A machining process has been developed as a new method to make nanostructured metals or alloys. Through the process, severe plastic deformation can be applied to metals or alloys and they become ultrafine grain and nanocrystalline in their structures. Because ultrafine grained alloys made by machining are made up to small chips, not bulk, to make bulk material, the alloy chips must be densified through processes such as sintering. Unfortunately, during the conventional sintering, the ultrafine grained alloys show grain growth at high rate and lose their hardness and strength. Therefore, low-temperature densification of ultrafine grained alloys has been pursued. In this thesis, ultrafine-grained (UFG) Al 6061-T6 particulate produced from machining chips have been consolidated and bonded using liquid epoxies that cure at 100?, below the coarsening temperature of the UFG structure. Two routes were explored---die-pressing premixed alloy particulate and epoxy and pressure infiltration of pre-pressed alloy particulate preforms. The effects of pressing pressure and epoxy viscosity were investigated. In order to reduce porosity and contamination, three treatments---application of pressure during curing of epoxy, the cleaning of the alloy powder with NaOH solution and degassing epoxy before pressing---were tried. In order to overcome limitation of diepressing, infiltration method was compared with die-pressing and the resulting properties of the composite discussed. Bond thickness between the alloy particles increases with the viscosity of the epoxies. In the hardness results by micro-indentor, the value of composite with more than 80% volume fraction of Al alloy chip (Va) was more than 120 kg/mm2. In those measurements, the hardness of the composite depends mainly on the volume fraction of Al alloy and was clearly influenced by the boundary

  7. Changes in pulmonary lavage fluid of guinea pigs exposed to ultrafine zinc oxide with adsorbed sulfuric acid

    SciTech Connect

    Conner, M.W.; Flood, W.H.; Rogers, A.E.; Amdur, M.O.

    1989-01-01

    Ultrafine metal oxide particles (diameters less than 0.1 microns) and sulfur dioxide are important products of coal combustion. Interaction of these products in the effluent stream results in formation of ultrafine particles with adsorbed sulfur compounds, including sulfuric acid. The toxicity of ultrafine zinc oxide particles with adsorbed sulfuric acid was evaluated by comparing pulmonary lavage fluid from guinea pigs exposed for 1, 2, 3, 4, or 5 consecutive daily 3-h periods to ultrafine zinc oxide generated in the presence of sulfur dioxide (ZnO + SO/sub 2/) to pulmonary lavage fluid from guinea pigs exposed to an equivalent concentration of ultrafine ZnO. Two groups of guinea pigs exposed either to SO/sub 2/ or to particle-free furnace gas served as additional controls. Cells, protein, and activities of lactate dehydrogenase, acid phosphatase, and alkaline phosphatase were increased in lavage fluid obtained from guinea pigs exposed to ZnO + SO/sub 2/ as compared to guinea pigs exposed to ZnO. These results demonstrate the potential importance of ultrafine metal oxides as carries of sulfuric acid derived from fossil fuel combustion.

  8. Evaluation of PVP/Au Nanocomposite Fibers as Heterogeneous Catalysts in Indole Synthesis.

    PubMed

    Savva, Ioanna; Kalogirou, Andreas S; Achilleos, Mariliz; Vasile, Eugenia; Koutentis, Panayiotis A; Krasia-Christoforou, Theodora

    2016-01-01

    Electrospun nanocomposite fibers consisting of crosslinked polyvinylpyrrolidone (PVP) chains and gold nanoparticles (Au NPs) were fabricated, starting from highly stable PVP/Au NP colloidal solutions with different NP loadings, followed by thermal treatment. Information on the morphological characteristics of the fibers and of the embedded Au NPs was obtained by electron microscopy. Cylindrical, bead-free fibers were visualized by Scanning Electron Microscopy (SEM) while Transmission Electron Microscopy (TEM) and Energy Diffraction X-ray (EDX) analysis supported the presence of Au NPs within the fibers and gave information on their morphologies and average diameters. These materials were briefly evaluated as heterogeneous catalytic supports for the gold-catalyzed intramolecular cyclisation of 2‑(phenylethynyl)aniline to form 2-phenyl-1H-indole. The performance of the gold catalyst was strongly dependent on the Au NP size, with the system containing the smallest Au NPs being the more effective. Moreover, a slight drop of their catalytic efficiency was observed after three consecutive reaction runs, which was attributed to morphological changes as a consequence of fiber merging. PMID:27626399

  9. Ultrafine particle size distribution during high velocity impact of high density metals

    NASA Astrophysics Data System (ADS)

    Buonanno, Giorgio; Stabile, Luca; Ruggiero, Andrew; Iannitti, Gianluca; Bonora, Nicola

    2011-06-01

    In the event of kinetic energy penetrator impact, survival personnel is exposed to the additional hazard stemming from ultrafine metallic particles, i.e. exposure, inhalation, and respiration of aerolized metals. Aerosol particle size distribution is an important parameter that influences aerosol transport and deposition processes. In order to have reliable quantitative measure of the aerosol particles generated under controlled impact conditions, an experimental set-up has been developed. Both non penetrating and penetrating impacts tests have been designed and performed with light gas-gun in chamber. During the impact, size distribution, total concentration and chemical composition of ultrafine particles have been measured and correlated with impact parameters (such as energy and velocity). In order to avoid measurement contamination, as a result of undesired participating materials, target and projectile have been made of the same metal and tests have been performed in clean environmental chamber. In this study the results relative to high purity copper are presented.

  10. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles

    PubMed Central

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-01-01

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm3. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 104 /cm3 and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

  11. Ultrafine particles emitted by flame and electric arc guns for thermal spraying of metals.

    PubMed

    Bémer, Denis; Régnier, Roland; Subra, Isabelle; Sutter, Benjamin; Lecler, Marie T; Morele, Yves

    2010-08-01

    The ultrafine aerosol emitted by thermal spraying of metals using flame and electric arc processes has been characterized in terms of particle size distribution and emission rates based on both particle number and mass. Thermal spraying of Zn, Zn/Al, and Al was studied. Measurements taken using an electrical low pressure impactor and a condensation nucleus counter reveal an aerosol made up of very fine particles (80-95% of number distribution <100 nm). Ultrafine particle emission rates produced by the electric arc process are very high, the largest values being recorded during spraying of pure aluminium. This process generates high particle emissions and therefore requires careful consideration and possible rethinking of currently implemented protection measures: ventilated cabins, dust collectors, and personal protective equipment. PMID:20685717

  12. Effect of nano-coated stencil on ultra-fine pitch printing

    NASA Astrophysics Data System (ADS)

    Hoogar, Sharan

    The growing demand for compact handheld devices with increased functionality has posed new challenges to the electronics board assembly industry. The introduction of ultra-fine pitch components has elevated importance of the stencil printing process. The stencil printing process has been attributed to more than 50 percent of the total defects in Level 2 electronics assemblies as noted in many prior studies [Clouthier, 1997]. Achieving a good print can drastically reduce overall defects and rework costs. One of the major factors for a "good" print is the paste transfer efficiency (TE). TE is defined as the ratio of measured paste volume to the theoretical volume of the stencil aperture. The latest stencil technology available for ultra-fine pitch printing is the introduction of "nano-coated stencils". In this study, we will investigate the claim that a nano-coated stencil has better transfer efficiency than standard laser cut and electroformed stencils that lack this coating.

  13. Inverse temperature dependence of toughness in an ultrafine grain-structure steel.

    PubMed

    Kimura, Yuuji; Inoue, Tadanobu; Yin, Fuxing; Tsuzaki, Kaneaki

    2008-05-23

    Materials are typically ductile at higher temperatures and become brittle at lower temperatures. In contrast to the typical ductile-to-brittle transition behavior of body-centered cubic (bcc) steels, we observed an inverse temperature dependence of toughness in an ultrahigh-strength bcc steel with an ultrafine elongated ferrite grain structure that was processed by a thermomechanical treatment without the addition of a large amount of an alloying element. The enhanced toughness is attributed to a delamination that was a result of crack branching on the aligned {100} cleavage planes in the bundles of the ultrafine elongated ferrite grains strengthened by nanometer-sized carbides. In the temperature range from 60 degrees to -60 degrees C, the yield strength was greater, leading to the enhancement of the toughness. PMID:18497294

  14. Ultrafine fully-lamellar structures in two-phase {gamma}-TiAl alloys

    SciTech Connect

    Maziasz, P.J.; Liu, C.T.

    1996-12-31

    Special ultrafine fully lamellar microstructures have been found recently in {gamma}-TiAl alloys with 46-48% Al processed or heat treated above the {alpha}-transus temperature (T{alpha}). Hot extrusion above T{alpha} also produces a refined colony or grain size. Refined-colony/ultrafine-lamellar (RC/UL) microstructures produce an excellent combination of RT ductility and high-temperature strength in Ti-47Al-2Cr-2Nb (at.%) alloys. UL structures also have regularly alternating {gamma} and {alpha}{sub 2} lamellae, such that they are dominated by {gamma}/{alpha}{sub 2} interfaces with relatively few {gamma}/{gamma} twin boundaries. Focus of this study is on how changes in processing parameters or alloy composition affect formation of the UL structure, particularly the {alpha}{sub 2} component.

  15. Estimation of Fracture Toughness of Small-Sized Ultrafine-Grained Specimens

    NASA Astrophysics Data System (ADS)

    Deryugin, E. E.; Suvorov, B. I.

    2015-10-01

    The results obtained from measurements of the crack resistance of a VT6 alloy (Ti-6.46Al-3.84V in wt.%) produced by refining coarse-crystalline structure down to an ultrafine-grained state, using a triaxial forging technique, are presented. The specific fracture energy γc is calculated by means of a new procedure developed for small-sized chevron-notched specimens. Severe plastic deformation is shown to cause a substantial reduction in γc at room temperature. Fracture surface structure found in the ultrafine-grained alloy under study contains local zones of a severely deformed material characterized by high pore concentration. This type of structure cannot be formed solely by crystallographic shearing along densely packed lattice planes. This is evidence for a significant role of rotation deformation modes in crack nucleation and growth on different structural scales of the material.

  16. Study on ultra-fine w-EDM with on-machine measurement-assisted

    SciTech Connect

    Chen Shuntong; Yang Hongye

    2011-01-17

    The purpose of this study was to develop the on-machine measurement techniques so as to precisely fabricate micro intricate part using ultra-fine w-EDM. The measurement-assisted approach which employs an automatic optical inspection (AOI) is incorporated to ultra-fine w-EDM process to on-machine detect the machining error for next re-machining. The AOI acquires the image through a high resolution CCD device from the contour of the workpiece after roughing in order to further process and recognize the image for determining the residual. This facilitates the on-machine error detection and compensation re-machining. The micro workpiece and electrode are not repositioned during machining. A fabrication for a micro probe of 30-{mu}m diameter is rapidly machined and verified successfully. Based on the proposed technique, on-machine measurement with AOI has been realized satisfactorily.

  17. Synthesis of high-strength W-Ta ultrafine-grain composites

    SciTech Connect

    Ott, R. T.; Yang, X. Y.; Guyer, D. E.; Chauhan, S.; Sordelet, D. J.

    2015-09-30

    Bulk samples of an ultrafine-grained tungsten–tantalum composite alloy have been synthesized by consolidating mechanically milled composite powders. The grain growth during densification is limited due to the submicron-scale layering of the individual metals in the composite particles and the relatively low sintering temperature (1300 °C). The ultrafine microstructure of the high-density (~99% theoretical density) samples leads to a high yield stress of ~3 GPa under quasi-static uniaxial compression. A tendency for Ta-rich solid-solution formation during densification was observed, and the high-temperature phase equilibria in the composite powders were examined further using high-energy x-ray diffraction at temperatures up to 1300 °C.

  18. Size evolution of ultrafine particles: Differential signatures of normal and episodic events.

    PubMed

    Joshi, Manish; Khan, Arshad; Anand, S; Sapra, B K

    2016-01-01

    The effect of fireworks on the aerosol number characteristics of atmosphere was studied for an urban mega city. Measurements were made at 50 m height to assess the local changes around the festival days. Apart from the increase in total number concentration and characteristic accumulation mode, short-term increase of ultrafine particle concentration was noted. Total number concentration varies an order of magnitude during the measurement period in which peak occurs at a frequency of approximately one per day. On integral scale, it seems not possible to distinguish an episodic (e.g. firework bursting induced aerosol emission) and a normal (ambient atmospheric changes) event. However these events could be differentiated on the basis of size evolution analysis around number concentration peaks. The results are discussed relative to past studies and inferences are drawn towards aerosol signatures of firework bursting. The short-term burst in ultrafine particle concentration can pose an inhalation hazard. PMID:26552523

  19. A Micro Aerosol Sensor for the Measurement of Airborne Ultrafine Particles.

    PubMed

    Zhang, Chao; Zhu, Rong; Yang, Wenming

    2016-01-01

    Particle number concentration and particle size are the two key parameters used to characterize exposure to airborne nanoparticles or ultrafine particles that have attracted the most attention. This paper proposes a simple micro aerosol sensor for detecting the number concentration and particle size of ultrafine particles with diameters from 50 to 253 nm based on electrical diffusion charging. The sensor is composed of a micro channel and a couple of planar electrodes printed on two circuit boards assembled in parallel, which thus integrate charging, precipitating and measurement elements into one chip, the overall size of which is 98 × 38 × 25 mm³. The experiment results demonstrate that the sensor is useful for measuring monodisperse aerosol particles with number concentrations from 300 to 2.5 × 10⁴ /cm³ and particle sizes from 50 to 253 nm. The aerosol sensor has a simple structure and small size, which is favorable for use in handheld devices. PMID:26999156

  20. Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility

    PubMed Central

    Wu, Xiaolei; Yang, Muxin; Yuan, Fuping; Wu, Guilin; Wei, Yujie; Huang, Xiaoxu; Zhu, Yuntian

    2015-01-01

    Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems. PMID:26554017

  1. Transforming anatase TiO2 nanorods into ultrafine nanoparticles for advanced electrochemical performance

    NASA Astrophysics Data System (ADS)

    Bresser, Dominic; Kim, Guk-Tae; Binetti, Enrico; Striccoli, Marinella; Comparelli, Roberto; Seidel, Stefan; Ozkaya, Dogan; Copley, Mark; Bishop, Peter; Paillard, Elie; Passerini, Stefano

    2015-10-01

    While the primary reason for nanostructuring lithium-ion active materials is commonly the realization of shorter diffusion pathways for ions and electrons, there are also other, less-expected phenomena occurring when leaving the microscale to enter the nanoscale. Herein, we will present one of these phenomena - the thermally induced fragmentation (i.e., "chopping") of oleic acid-capped anatase TiO2 nanorods perpendicular to the [001] direction. This fragmentation results in the formation of ultrafine TiO2 nanoparticles with increased (001) facets. Due to this modified surface facets ratio and the advantageous utilization of carboxymethyl cellulose as binder, these ultrafine nanoparticles present an excellent rate performance and cycling stability - even for cathodic cut-off potentials as low as 0.1 V.

  2. Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility.

    PubMed

    Wu, Xiaolei; Yang, Muxin; Yuan, Fuping; Wu, Guilin; Wei, Yujie; Huang, Xiaoxu; Zhu, Yuntian

    2015-11-24

    Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as conventional coarse-grained metal. It also has higher strain hardening than coarse-grained Ti, which was hitherto believed impossible. The heterogeneous lamella structure is characterized with soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The unusual high strength is obtained with the assistance of high back stress developed from heterogeneous yielding, whereas the high ductility is attributed to back-stress hardening and dislocation hardening. The process discovered here is amenable to large-scale industrial production at low cost, and might be applicable to other metal systems. PMID:26554017

  3. Ultrafine metal particles immobilized on styrene/acrylic acid copolymer particles

    SciTech Connect

    Tamai, Hisashi; Hamamoto, Shiro; Nishiyama, Fumitaka; Yasuda, Hajime

    1995-04-01

    Ultrafine metal particles immobilized on styrene/acrylic acid copolymer fine particles were produced by reducing the copolymer particles-metal ion complexes or refluxing an ethanol solution of metal ions in the presence of copolymer particles. The size of metal particles formed by reduction of the complex is smaller than that by reflux of the metal ion solution and depends on the amount of metal ions immobilized.

  4. Analysis of ultrafine TATB by ultrasonic-assisted equilibrium headspace analysis

    SciTech Connect

    Chambers, D M

    2000-09-12

    The purpose of this work was to screen different lots of ultrafine 1,3,5-triamine 2,4,6-trinitrobenzene (TATB) for chemical differences, which may include synthesis and formulation byproducts, decomposition products, and contaminants. The approach used here permits analysis of trapped species as volatile and semivolatile chemicals within a solid. This procedure involves preconcentration of species from the TATB matrix into a surrounding headspace followed by a preconcentration and collection step using solid phase microextraction (SPME) collection. The sample is prepared by sealing it in a glass ampule with a few milliliters of water, ultrasonicating the solution, and then sampling the headspace using SPME collection. Water couples in the ultrasonic energy to fracture the TATB, which permits the release of nonpolar species into the gas phase. However, polar species will favor the aqueous phase and require a separate analysis procedure, which is not included here. Following SPME collection, the sample is transferred to a gas chromatography/mass spectrometer (GCMS) for analysis. In this work, we analyzed and interpreted outgas signatures from four different lots (1169-135MPS-001, 4271-135M-002, 91190-135M-003, and 98170-135M-001) of ultrafine TATB. Lot 98170-135M-001 is a reprocessing of Lot 4271-135M-002, which was washed to remove the water-soluble polysaccharides. The pedigree for these materials are found in a memo from Tom Stallings and Gordon Osborn of Mason & Hanger Co., Pantex Plant in the Appendix section. Nominally, ultrafine TATB is synthesized via the emulsion-amination method in which an emulsifier is included during the amination of the 1,3,5-trichloro-2,4,6-trinitrobenzene (TCTNB) precursor. The ultrafine TATB formulation also includes 0.2% by weight guar gum, a galactomannan polysaccharide, to enhance flow properties. Historically, this polysaccharide was added to PETN to reduce its sublimation temperature, but it was also found to enhance flow

  5. Growth mechanism of ultrafine tellurium particles produced by the gas evaporation method

    NASA Astrophysics Data System (ADS)

    Kaito, Chihiro; Saito, Yoshio; Watanabe, Tsuyoshi; Ohtsuka, Kazushi; Chen, Fangyu; Nakamura, Masahiko

    1994-06-01

    Ultrafine particles of tellurium have been produced by evaporating tellurium powder from a quartz boat using the atmospheric temperature. Particles of 20-200 nm in size grew under low vapor pressure of tellurium. The shapes of the particles were sphere and hexagonal rod. Spherical amorphous particles also grew in the smoke. Hollow hexagonal rod particles grew under high vapor pressure of tellurium. The growth mechanism of these particles is discussed on the basis of atmospheric temperature and the vapor pressure of tellurium.

  6. Ultrafine potassium titanate nanowires: a new Ti-based anode for sodium ion batteries.

    PubMed

    Zhang, Qing; Guo, Yanpeng; Guo, Kai; Zhai, Tianyou; Li, Huiqiao

    2016-05-01

    K2Ti6O13 with an analogous tunnel structure to Na2Ti6O13 is proposed as a new anode for sodium-ion batteries. By fabricating ultrafine nanowires growing perpendicularly to the Na(+) diffusion direction, the K2Ti6O13 nanowires show a much enhanced capacity (186 mA h g(-1)) as well as good rate capability for sodium storage. PMID:26980665

  7. [Research on NEDC ultrafine particle emission characters of a port fuel injection gasoline car].

    PubMed

    Hu, Zhi-Yuan; Li, Jin; Tan, Pi-Qiang; Lou, Di-Ming

    2012-12-01

    A Santana gasoline car with multi-port fuel injection (PFI) system was used as the research prototype and an engine exhaust particle sizer (EEPS) was employed to investigate the exhaust ultrafine particle number and size distribution characters of the tested vehicle in new European driving cycle (NEDC). The tested results showed that the vehicle's nuclear particle number, accumulation particle number, as well as the total particle number emission increased when the car drove in accelerated passage, and the vehicle's particle number emission was high during the first 40 seconds after test started and when the speed was over 90 km x h(-1) in extra urban driving cycle (EUDC) in NEDC. The ultrafine particle distribution of the whole NEDC showed a single peak logarithmic distribution, with diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameter was 24 nm. The ultrafine particle distribution of the urban driving cycle named by the economic commission for Europe (ECE) e. g. ECE I, ECE II - IV, the extra urban driving cycle e. g. EUDC, and the idling, constant speed, acceleration, deceleration operation conditions of NEDC all showed a single peak logarithmic distribution, also with particle diameters of the peak particle number emission ranging from 10 nm to 30 nm, and the geometric mean diameters of different driving cycle and different driving mode were from 14 nm to 42 nm. Therefore, the ultrafine particle emissions of the tested PFI gasoline car were mainly consisted of nuclear mode particles with a diameter of less than 50 nm. PMID:23379140

  8. Effect of flow characteristics on ultrafine particle emissions from range hoods.

    PubMed

    Tseng, Li-Ching; Chen, Chih-Chieh

    2013-08-01

    In order to understand the physical mechanisms of the production of nanometer-sized particulate generated from cooking oils, the ventilation of kitchen hoods was studied by determining the particle concentration, particle size distribution, particle dimensions, and hood's flow characteristics under several cooking scenarios. This research varied the temperature of the frying operation on one cooking operation, with three kinds of commercial cooking oils including soybean oil, olive oil, and sunflower oil. The variations of particle concentration and size distributions with the elevated cooking oil temperatures were presented. The particle concentration increases as a function of temperature. For oil temperatures ranging between 180°C and 210°C, a 5°C increase in temperature increased the number concentration of ultrafine particles by 20-50%. The maximum concentration of ultrafine particles was found to be approximately 6 × 10(6) particles per cm(3) at 260°C. Flow visualization techniques and particle distribution measurement were performed for two types of hood designs, a wall-mounted range hood and an island hood, at a suction flow rate of 15 m(3) min(-1). The flow visualization results showed that different configurations of kitchen hoods induce different aerodynamic characteristics. By comparing the results of flow visualizations and nanoparticle measurements, it was found that the areas with large-scale turbulent vortices are more prone to dispersion of ultrafine particle leakage because of the complex interaction between the shear layers and the suction movement that results from turbulent dispersion. We conclude that the evolution of ultrafine particle concentration fluctuations is strongly affected by the location of the hood, which can alter the aerodynamic features. We suggest that there is a correlation between flow characteristics and amount of contaminant leakage. This provides a comprehensive strategy to evaluate the effectiveness of kitchen hoods

  9. Sintering behavior of ultrafine silicon carbide powders obtained by vapor phase reaction

    NASA Technical Reports Server (NTRS)

    Okabe, Y.; Miyachi, K.; Hojo, J.; Kato, A.

    1984-01-01

    The sintering behavior of ultrafine SiC powder with average particle size of about 0.01-0.06 microns produced by a vapor phase reaction of the Me4Si-H2 system was studied at the temperature range of 1400-2050 deg. It was found that the homogeneous dispersion of C on SiC particles is important to remove the surface oxide layer effectively. B and C and inhibitive effect on SiC grain growth.

  10. The use of a solid-bowl centrifuge for ultrafine coal thickening

    SciTech Connect

    Pinkerton, A.P.; Klima, M.S.; Morrison, J.L.; Miller, B.G.

    2000-07-01

    Testing was carried out to investigate the use of a solid-bowl (decanter) centrifuge for thickening ultrafine coal-water slurries. This study was conducted for Electric Power Research Institute's (EPRI's) Upgraded Coal Interest Group (UCIG) to evaluate ultrafine dewatering technologies. The objective was to increase the solids concentration of an ultrafine coal discard stream to a level suitable for use as a coal-water slurry fuel, while maximizing overall solids recovery. The feed material was collected from the combined discharge (centrate) streams from several screen-bowl centrifuges, which are currently being used in a commercial coal cleaning facility to dewater froth flotation product. The centrate averages 5% solids by weight and contains nearly 60% material finer than 10 {micro}m. This study examined the effects of operating conditions on centrifuge performance, including centrifuge bowl and scroll speeds, and feed solids concentration. The effects of flocculation addition on centrifuge performance and slurry rheology were also examined. The results indicated that solids concentrations exceeding 55% were obtained in nearly all cases.

  11. Existence of ultrafine crevices and functional groups along the edge surfaces of graphitized thermal carbon black.

    PubMed

    Zeng, Yonghong; Do, D D; Nicholson, D

    2015-04-14

    Adsorption of different gases on graphitized thermal carbon black (GTCB) has been studied with a new molecular model to examine the consequences of micropore crevices and functional groups at the junctions between adjacent basal planes. Adsorption was simulated in the Grand Canonical Monte Carlo ensemble and the theoretical Henry constants were calculated by Monte Carlo volume integration over the Boltzmann factor of the solid-fluid potential. The simulation results are in good agreement with high-resolution experimental isotherms for argon on mineralogical graphite measured by Lopez-Gonzalez et al.1 From detailed inspection of the argon isotherms at extremely low coverages, we find two distinct Henry law regions, separated by a plateau (suggesting saturation of the stronger sites) that spans over a few decades of pressure. The first Henry law region is attributed to adsorption in the ultrafine crevices at the junctions between two adjacent basal planes, and the second region corresponds to adsorption on the basal plane, as confirmed by the theoretical Henry constant. The simulated isosteric heat and snapshots of molecular configurations show that argon adsorbs preferentially in the ultrafine crevices where there is a deep potential well due to overlap from the opposite pore walls. Similar behavior was found for other nonassociating fluids (Ar, N2, and CO2); however, for associating fluids (NH3 and H2O), the strong sites for adsorption and nucleation come from the combined effects of functional groups and ultrafine crevices, since the latter cannot alone account for the observed adsorption. PMID:25797845

  12. Ultrafine particle emission of waste incinerators and comparison to the exposure of urban citizens.

    PubMed

    Buonanno, Giorgio; Morawska, Lidia

    2015-03-01

    On the basis of the growing interest on the impact of airborne particles on human exposure as well as the strong debate in Western countries on the emissions of waste incinerators, this work reviewed existing literature to: (i) show the emission factors of ultrafine particles (particles with a diameter less than 100 nm) of waste incinerators; and (ii) assess the contribution of waste incinerators in terms of ultrafine particles to exposure and dose of people living in the surrounding areas of the plants in order to estimate eventual risks. The review identified only a limited number of studies measuring ultrafine particle emissions, and in general they report low particle number concentrations at the stack (the median value was equal to 5.5×10(3) part cm(-3)), in most cases higher than the outdoor background value. The lowest emissions were achieved by utilization of the bag-house filter which has an overall number-based filtration efficiency higher than 99%. Referring to reference case, the corresponding emission factor is equal to 9.1×10(12) part min(-1), that is lower than one single high-duty vehicle. Since the higher particle number concentrations found in the most contributing microenvironments to the exposure (indoor home, transportation, urban outdoor), the contribution of the waste incinerators to the daily dose can be considered as negligible. PMID:24726660

  13. Formation and Microstructure of Ultrafine-Grained Titanium Processed by Multi-Directional Forging

    NASA Astrophysics Data System (ADS)

    Wang, Bingfeng; Wang, Xiaoyan; Li, Juan

    2016-06-01

    Ultrafine-grained titanium with uniform grain size for medical applications is obtained by multi-directional forging at 773 K in air. The microstructures and microtextures in the deformed titanium specimens are investigated by optical microscopy, electron backscattered diffraction technique, and transmission electron microscopy. Titanium specimen experience the recrystallization softening at cumulative strain about 1.2. After six passes with the cumulative strains of 2.4, the coarse grain sizes are gradually refined from about 25 μm to about 0.2 μm. New microtextures with recrystallized features generate in the specimens after multi-directional forgings. Grain boundaries in the specimens are geometrical necessary boundaries aiming to accommodate the imposed strain. It is suggested that the continuous dynamic recrystallization induced by deformation bands is responsible for the formation of ultrafine-grained titanium during multi-directional forging. Meanwhile the subdivision of grains by the mechanical twinning dramatically enhanced grain refinement to develop ultrafine-grained microstructure.

  14. The influence of reagent type on the kinetics of ultrafine coal flotation

    USGS Publications Warehouse

    Read, R.B.; Camp, L.R.; Summers, M.S.; Rapp, D.M.

    1989-01-01

    A kinetic study has been conducted to determine the influence of reagent type on flotation rates of ultrafine coal. Two ultrafine coal samples, the Illinois No. 5 (Springfield) and Pittsburgh No. 8, have been evaluated with various reagent types in order to derive the rate constants for coal (kc), ash (ka), and pyrite (kc). The reagents used in the study include anionic surfactants, anionic surfactant-alcohol mixtures, and frothing alcohols. In general, the surfactant-alcohol mixtures tend to float ultrafine coal at a rate three to four times faster than either pure alcohols or pure anionic surfactants. Pine oil, a mixture of terpene alcohols and hydrocarbons, was an exception to this finding; it exhibited higher rate constants than the pure aliphatic alcohols or other pure anionic surfactants studied; this may be explained by the fact that the sample of pine oil used (70% alpha-terpineol) acted as a frother/collector system similar to alcohol/kerosene. The separation efficiencies of ash and pyrite from coal, as evidenced by the ratios of kc/ka or kc/kp, tend to indicate, however, that commercially available surfactant-alcohol mixtures are not as selective as pure alcohols such as 2-ethyl-1-hexanol or methylisobutylcarbinol. Some distinct differences in various rate constants, or their ratios, were noted between the two coals studied, and are possibly attributable to surface chemistry effects. ?? 1989.

  15. Associations Between Ultrafine Particles and Co-Pollutant Concentrations in the Tampa Bay Area.

    PubMed

    Desai, Ushang; Watson, Alain

    2016-05-01

    Ultrafine particles (UFPs) are ubiquitous in urban air and have been recognized as a risk to human health. The aim of this study was to measure the relationships among ultrafine particles and other ambient air pollutants and meteorological factors in the Tampa Bay Area. This study measured continuous UFPs, black carbon, oxides of nitrogen (NO(x)), nitrogen dioxide (NO2), nitric oxide (NO), carbon monoxide (CO), ozone (O3), sulfur dioxide (SO2), particulate matter having an aerodynamic diameter of 10 microns or less (PM10), relative humidity, wind speed, and ambient temperature during January to March 2014. Moreover, the study compared the relationship between UFPs and various co-pollutants daily, including during morning rush hour periods. This study found a moderate correlation among UFPs and black carbon, NO(x), NO2, and NO during hourly continuous measurements and rush hour periods, and a low level of correlation among UFPs and CO, O3, SO2, PM10, relative humidity, wind speed, and ambient temperature. This study indicates that co-pollutants should not be used as a surrogate to assess the human health risk from ultrafine particles exposure. PMID:27263179

  16. Ultrafine coal single stage dewatering and briquetting process. Technical report, September 1--November 30, 1994

    SciTech Connect

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

    1994-12-31

    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 that are produced are difficult to dewater and they create problems in coal transportation as well as in its storage and handling at utility plants. The objective of this research project is to combine 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, two types of coal samples have been tested for use in the dewatering and briquetting processes. These tests were carried out in conjunction with a selected hydrophobic binder as the dewatering reagent and an uniaxial hydraulic press. The influence of compaction pressure and binder concentration (2 to 5%) on the performance of coal pellets have been evaluated in terms of their water and wear resistance. A laboratory scale ultrafine coal dewatering and briquetting extruder that can be operated continuously for coal pellets fabrication, has been designed and built, and will be available for testing in the next quarter.

  17. Preparation of ultrafine silica from potash feldspar using sodium carbonate roasting technology

    NASA Astrophysics Data System (ADS)

    Liu, Jia-nan; Shen, Xiao-yi; Wu, Yan; Zhang, Jun; Zhai, Yu-chun

    2016-08-01

    A novel process was developed for the preparation of ultrafine silica from potash feldspar. In the first step, potash feldspar was roasted with Na2CO3 and was followed by leaching using NaOH solution to increase the levels of potassium, sodium, and aluminum in the solid residue. The leaching solution was then carbonated to yield ultrafine silica. The optimized reaction conditions in the roasting process were as follows: an Na2CO3-to-potash feldspar molar ratio of 1.1, a reaction temperature of 875°C, and a reaction time of 1.5 h. Under these conditions, the extraction rate of SiO2 was 98.13%. The optimized carbonation conditions included a final solution pH value of 9.0, a temperature of 40°C, a CO2 flow rate of 6 mL/min, a stirring intensity of 600 r/min, and an ethanol-to-water volume ratio of 1:9. The precipitation rate and granularity of the SiO2 particles were 99.63% and 200 nm, respectively. We confirmed the quality of the obtained ultrafine silica by comparing the recorded indexes with those specified in Chinese National Standard GB 25576―2010.

  18. Single Particle Chemical Speciation of Ambient Ultrafine Particulate Matter in Atlanta, GA

    NASA Astrophysics Data System (ADS)

    Sipin, M. F.; Su, Y.; Prather, K. A.

    2002-12-01

    Ultrafine particles, particles with aerodynamic diameters lower than 100 nm, have recently gained increasing attention because of their hypothesized adverse heath effects and potential as cloud condensation nuclei. Chemical characterization of the ultrafine particles at the single particle level is important for assessing their impact on human health and understanding their formation and behavior. This is beneficial for modeling studies and regulations on pollution control. In August 2002, continuous ambient monitoring was performed in an industrial area in Atlanta, GA. Characterization of the urban particulate matter with aerodynamic diameters 30A›ƒ,ªƒ_o300 nm was carried out using a dual polarity aerosol time-of-flight mass spectrometer (ATOFMS) interfaced with an aerodynamic lens system. This configuration allows on-line real time simultaneous acquisition of size and chemical information for individual particles down to 30 nm. The ultrafine particles observed consisted of elemental carbon (EC), organic carbon (OC), and a mixture of OC and EC as a result of vehicular, industrial, and biogenic emissions. These major particle types, their associations with inorganics (i.e. ammonium, sulfate, nitrate, potassium, calcium, and metal oxides), and their temporal and size variations will be presented.

  19. An innovative antisolvent precipitation process as a promising technique to prepare ultrafine rifampicin particles

    NASA Astrophysics Data System (ADS)

    Viçosa, Alessandra; Letourneau, Jean-Jacques; Espitalier, Fabienne; Inês Ré, Maria

    2012-03-01

    Many existing and new drugs fail to be fully utilized because of their limited bioavailability due to poor solubility in aqueous media (BCS drug classes II and IV). In this work, for accelerating dissolution of this kind of poorly water-soluble drugs, an antisolvent precipitation method that does not require the use of conventional volatile organic solvents is proposed. To demonstrate this technique, ultrafine particles of rifampicin were prepared using a room temperature ionic liquid (1-ethyl 3- methyl imidazolium methyl-phosphonate) as an alternative solvent and a phosphate buffer as an antisolvent. Rifampicin solubility was measured in various solvents (1-ethyl 3-methyl imidazolium methylphosphonate, water and phosphate buffer), showing the RTIL good solvency for the model drug: rifampicin solubility was found to be higher than 90 mg/g in RTIL at 30 °C and lower than 1 mg/g in water at 25 °C. Additionally, it was demonstrated that introduction of rifampicin solution in 1-ethyl 3- methyl imidazolium methyl-phosphonate into the aqueous solution antisolvent can produce particles in the submicron range with or without hydroxypropyl methylcellulose as the stabilizer. The ultrafine particles (280-360 nm) are amorphous with enhanced solubility and faster dissolution rate. To our knowledge, this is the first published work examining the suitability of using RTILs for ultrafine drug nanoparticles preparation by an antisolvent precipitation process.

  20. Multimodal ultrafine particles from pulverized coal combustion in a laboratory scale reactor

    SciTech Connect

    Carbone, Francesco; Beretta, Federico; D'Anna, Andrea

    2010-07-15

    Particle size distribution functions have been measured in a ethanol fueled flame reactor fed with a low amount of pulverized coal particles. The reactor is operated in low (5.0 vol.%) and high (76.5 vol.%) oxygen concentrations using two high volatile bituminous Colombian and Indonesian coals. A carbon black powder is also oxidized in the same conditions. Generated particles are sampled using rapid-dilution probes and the size distribution functions are measured on-line by a high resolution Differential Mobility Analyzer. Results clearly show that ultrafine particles, those with sizes lower than 100 nm, have a multimodal size distribution function. These particles have huge number concentrations in both investigated conditions whereas their formation is enhanced in the oxygen enriched condition. Ultrafine particles are almost totally dominated in number by the fraction having sizes below 30 nm. Nanoparticles also account for a significant fraction of total particle mass and slowly coagulate in the reactor. The shape of the size distribution functions is not affected by the coal type, at least for the two investigated coals. Results suggest that ultrafine particles form through the vaporization-nucleation-growth pathway involving inorganic ashes. Moreover the contribution of carbonaceous particles seems particularly important for size smaller than 5 nm. (author)

  1. Formation and Microstructure of Ultrafine-Grained Titanium Processed by Multi-Directional Forging

    NASA Astrophysics Data System (ADS)

    Wang, Bingfeng; Wang, Xiaoyan; Li, Juan

    2016-05-01

    Ultrafine-grained titanium with uniform grain size for medical applications is obtained by multi-directional forging at 773 K in air. The microstructures and microtextures in the deformed titanium specimens are investigated by optical microscopy, electron backscattered diffraction technique, and transmission electron microscopy. Titanium specimen experience the recrystallization softening at cumulative strain about 1.2. After six passes with the cumulative strains of 2.4, the coarse grain sizes are gradually refined from about 25 μm to about 0.2 μm. New microtextures with recrystallized features generate in the specimens after multi-directional forgings. Grain boundaries in the specimens are geometrical necessary boundaries aiming to accommodate the imposed strain. It is suggested that the continuous dynamic recrystallization induced by deformation bands is responsible for the formation of ultrafine-grained titanium during multi-directional forging. Meanwhile the subdivision of grains by the mechanical twinning dramatically enhanced grain refinement to develop ultrafine-grained microstructure.

  2. Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium-Oxygen Batteries.

    PubMed

    Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E; Wang, Chong-Min; Zhang, Ji-Guang

    2016-08-10

    Lithium-oxygen (Li-O2) batteries have an extremely high theoretical specific energy density when compared with conventional energy-storage systems. However, practical application of the Li-O2 battery system still faces significant challenges. In this work, we report a new approach for synthesis of ultrafine metal oxide nanocatalysts through an electrochemical prelithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20-30 nm to a uniformly distributed domain of ∼2 nm and significantly improves their catalytic activity. Structurally, the prelithiated NCO nanowires feature ultrafine NiO/CoO nanoparticles that are highly stable during prolonged cycles in terms of morphology and particle size, thus maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. A Li-O2 battery using this catalyst demonstrated an initial capacity of 29 280 mAh g(-1) and retained a capacity of >1000 mAh g(-1) after 100 cycles based on the weight of the NCO active material. Direct in situ transmission electron microscopy observations conclusively revealed the lithiation/delithiation process of as-prepared NCO nanowires and provided in-depth understanding for both catalyst and battery chemistries of transition-metal oxides. This unique electrochemical approach could also be used to form ultrafine nanoparticles of a broad range of materials for catalyst and other applications. PMID:27380300

  3. Highly Porous Regenerated Cellulose Fiber Mats via the Co-Forcespinning of Cellulose Acetate for Separator Applications

    NASA Astrophysics Data System (ADS)

    Castillo, Alejandro; Mao, Yuanbing

    2015-03-01

    Improvements in battery technology are necessary for the transition away from a fossil fuel based economy. An important bottle-neck in battery efficiency is the quality of the separator, which separates the cathode and anode to prevent a short-circuit while still allowing the ions in solution to flow as close to unabated as possible. In this work solutions of cellulose acetate, polyvinyldiflourine (pvdf), and polyvinylpyrrolidone (pvp) dissolved in a 2:1 v/v acetone/dimethylacetamide solvent mixture were Forcespun to create nonwoven fiber mats of nanoscale diameter. These mats were then soaked in a NaOH solution so as to both strip the pvp from the fiber as well as regenerate cellulose from its acetate derivative for the purpose of creating high surface area, nanoporous, hydrophilic, and ioniclly conductive cellulose/pvdf nonwoven mats for the purposes of testing their suitability as battery separators

  4. PAHs, PAH-induced carcinogenic potency, and particle-extract-Induced cytotoxicity of traffic-related nano/ultrafine particles.

    PubMed

    Lin, Chih-Chung; Chen, Shui-Jen; Huang, Kuo-Lin; Lee, Wen-Jhy; Lin, Wen-Yinn; Tsai, Jen-Hsiung; Chaung, Hso-Chi

    2008-06-01

    Polycyclic aromatic hydrocarbons (PAHs) bound in nano/ ultrafine particles from vehicle emissions may cause adverse health effects. However, little is known about the characteristics of the nanoparticle-bound PAHs and the PAH-associated carcinogenic potency/cytotoxicity; therefore, traffic-related nano/ultrafine particles were collected in this study using a microorifice uniform deposition impactor(MOUDI) and a nano-MOUDI. For PM0.056--18, the difference in size-distribution of particulate total-PAHs between non-after-rain and after-rain samples was statistically significant at alpha = 0.05; however, this difference was not significant for PM0.01--0.056. The PAH correlation between PM0.01--0.1 and PM0.1--1.8 was lower for the after-rain samples than forthe non-after-rain samples. The average particulate total-PAHs in five samplings displayed a trimodal distribution with a major peak in the Aitken mode (0.032--0.056 microm). About half of the particulate total-PAHs were in the ultrafine size range. The BaPeq sums of BaP, IND, and DBA (with toxic equivalence factors > or = 0.1) accounted for approximately 90% of the total-BaPeq in the nano/ultrafine particles, although these three compounds contributed little to the mass of the sampled particles. The mean content of the particle-bound total-PAHs/-BaPeqs and the PAH/BaPeq-derived carcinogenic potency followed the order nano > ultrafine > fine > coarse. For a sunny day sample, the cytotoxicity of particle extracts (using 1:1 (v/v) n-hexane/dichloromethane) was significantly higher (p < 0.05) for the nano (particularly the 10-18 nm)/ultrafine particles than for the coarser particles and bleomycin. Therefore, traffic-related nano and ultrafine particles are possibly cytotoxic. PMID:18589992

  5. High Performance Dye-Sensitized Solar Cells with Enhanced Light-Harvesting Efficiency Based on Polyvinylpyrrolidone-Coated Au-TiO2 Microspheres.

    PubMed

    Ding, Yong; Sheng, Jiang; Yang, Zhenhai; Jiang, Ling; Mo, Li'e; Hu, Linhua; Que, Yaping; Dai, Songyuan

    2016-04-01

    Surface plasmon resonance using noble metal nanoparticles is regarded as an attractive and viable strategy to improve the optical absorption and/or photocurrent in dye-sensitized solar cells (DSSCs). However, no significant improvement in device performance has been observed. The bottleneck is the stability of the noble-metal nanoparticles caused by chemical corrosion. Here, we propose a simple method to synthesize high-performance DSSCs based on polyvinylpyrrolidone-coated Au-TiO2 microspheres that utilize the merits of TiO2 microspheres and promote the coupling of surface plasmons with visible light. When 0.4 wt % Au nanoparticles were embedded into the TiO2 microspheres, the device achieved a power conversion efficiency (PCE) as high as 10.49 %, a 7.9 % increase compared with pure TiO2 microsphere-based devices. Simulation results theoretically confirmed that the improvement of the PCE is caused by the enhancement of the absorption cross-section of dye molecules and photocurrent. PMID:26915757

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

    SciTech Connect

    Kuvibidila, S.; Wade, S.

    1987-01-01

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

  7. Photo-induced exciton generation in polyvinylpyrrolidone encapsulated Ag2S core-shells: Electrochemical deposition, regular shape and high order of particle size distribution

    NASA Astrophysics Data System (ADS)

    Mukherjee, Nillohit; Jana, Sumanta; Gopal Khan, Gobinda; Mondal, Anup

    2012-12-01

    Visible light induced frequency switching behavior, exhibited by the electrochemically deposited thin films of polyvinylpyrrolidone (PVP) encapsulated Ag2S nanosphere (core-shell) is shown here. A low frequency (˜40 Hz) pulse was found to be generated upon illumination with 1 Sun due to excitonic transition, which also showed good switching behavior with the "on" and "off" state of the light. Capping of the semiconductor surface by a polymer like PVP reduces the surface states and thus lowers the built in barrier height and the width of depletion region. So, the number of photo generated but non recombining electron-hole pairs (excitons) increases, which put their signature in some unique physical properties like increase in photoluminescence (PL) intensity, light induced frequency switching behavior due to free exciton generation, etc. Here, the depositions were carried out on indium tin oxide coated glass substrates from an aqueous solution of AgNO3, thioacetamide, and PVP. The films were structurally characterized using high resolution X-ray diffraction, field emission scanning electron microscopy, and high resolution transmission electron microscopic techniques. The deposited particles were regular in shape with significantly high order of size distribution. Furrier transform infrared spectroscopy confirmed the presence of PVP as the encapsulating agent. Optical characterization, viz., UV - vis - NIR and NIR-PL revealed noteworthy amount of NIR emission from the deposited material.

  8. Online Coupling of Lab-on-Valve Format to Amperometry Based on Polyvinylpyrrolidone-Doped Carbon Paste Electrode and Its Application to the Analysis of Morin

    PubMed Central

    Wang, Yang; Yao, Guojun; Tang, Jie; Yang, Chun; Xu, Qin; Hu, Xiaoya

    2012-01-01

    The potential capabilities and analytical performance of lab-on-valve (LOV) manifold as a front end to amperometry have been explored for the on-line determination of morin. Meanwhile, the electrochemical behaviors of morin were investigated based on polyvinylpyrrolidone- (PVP-) doped carbon paste electrode (CPE), which found that PVP can significantly improve its oxidation peak current. The excellent amperometric current response was achieved when the potential difference (ΔE) of 0.6 V was implemented in pH 6.5 phosphate buffer solution (PBS) that served as the supporting electrolyte. A well-defined oxidation peak has been obtained in studies using PVP as a modifier of CPE based on the oxidation of morin. The present work introduces the LOV technique as a useful tool for amperometric measurement, documents advantages of using programmable flow, and outlines means for miniaturization of assays on the basis of PVP modified CPE. The proposed method was applied successfully to the determination of morin in real samples, and the spiked recoveries were satisfactory. PMID:22567551

  9. Microfluidic preparation of a highly active and stable catalyst by high performance of encapsulation of polyvinylpyrrolidone (PVP)-Pt nanoparticles in microcapsules.

    PubMed

    Nam, Jin-Oh; Kim, Jongmin; Jin, Si Hyung; Chung, Young-Min; Lee, Chang-Soo

    2016-02-15

    The encapsulation of active metals in microcapsules would be highly advantageous in maintaining or improving the reaction performance of an array of widely used chemical reactions. However, conventional methods suffer from low uniformity, complicated fabrication steps, sintering, leaching, decline of catalytic activity, and/or poor reusability. Here, we report an efficient microfluidic approach to encapsulate Pt nanoparticle stabilized by polyvinylpyrrolidone (PVP) in photocurable double-emulsion droplets with semipermeable thin shells. The encapsulated catalysts are prepared by the in situ photopolymerization of a double emulsion. The rapid and exquisite microfluidics-based fabrication process successfully generates monodisperse microcapsules without loss of the PVP-Pt nanoparticles, which is the first demonstration of the microfluidic encapsulation of active metal with promising catalytic activity. Specifically, compared to quasi-homogeneous catalysis of PVP-Pt nanoparticles for 4-nitrophenol hydrogenation, the encapsulated PVP-Pt nanoparticles demonstrate excellent catalytic activity, a leaching-proof nature, and high reusability under the same reaction conditions. We envision that the approach described here may be an example of elegant catalyst design to efficiently overcome difficult problems in active-metal encapsulation and to dramatically enhance catalytic activity by taking advantage of the unique aspects of microfluidic methods. PMID:26624530

  10. Effect of Tannin-Binding Agents (Polyethylene Glycol and Polyvinylpyrrolidone) Supplementation on In Vitro Gas Production Kinetics of Some Grape Yield Byproducts

    PubMed Central

    Besharati, Maghsoud; Taghizadeh, Akbar

    2011-01-01

    The effects of polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP) on in vitro gas production characteristics, organic matter digestibility (OMD), and metabolizable energy (ME) contents of some grape yield byproducts were investigated. The gas production was recorded after 2, 4, 6, 8, 12, 16, 24, 36, and 48 h of incubation. The gas production profiles in triplicate fitted with equation Y = A (1 – e−ct). The data was analyzed using completely randomized design. Total phenol (TP) and total tannin (TT) contents were highest for raisin waste (RW). The TP content (g/kg DM) ranged from 30.1 in grape pomace (GP) to 96.3 in RW, which also had the higher TT (72.1 g/kg DM). The potential gas production (a + b) of DGB, GP, and RW were 239.43, 263.49, and 208.22 mL/g DM, respectively. In the absence of PEG and PVP, rate constant of gas production (c) for GP was highest among the feedstuffs (0.1073 mL/h), but in presence of PEG or PVP, RW had highest fraction (c) among the feedstuffs. Addition of PEG and PVP inactivated effects of tannins and increased gas production, ME, NE1, OMD, and VFA in grape yield byproducts. Addition of PEG and PVP could overcome adverse effects of tannins on nutrient availability as indicated by gas production parameters. PMID:23738107

  11. Effects of polyvinylpyrrolidone both as a binder and pore-former on the release of sparingly water-soluble topiramate from ethylcellulose coated pellets.

    PubMed

    Yang, Meiyan; Xie, Si; Li, Qiu; Wang, Yuli; Chang, Xinyi; Shan, Li; Sun, Lei; Huang, Xiaoli; Gao, Chunsheng

    2014-04-25

    Delivering sparingly water-soluble drugs from ethylcellulose (EC) coated pellets with a controlled-release pattern remains challenging. In the present study, hydrophilic polyvinylpyrrolidone (PVP) was used both as a binder and a pore-former in EC coated pellets to deliver sparingly water-soluble topiramate, and the key factors that influenced drug release were identified. When the binder PVP content in drug layers below 20% w/w was decreased, the physical state of topiramate changed from amorphous to crystalline, making much difference to drug solubility and dissolution rates while modifying the drug release profile from first-order to zero-order. In addition, without PVP in drug layering solution, drug layered particles were less sticky during layering process, thus leading to a shorter process and higher loading efficiency. Furthermore, PVP level as a pore-former in EC coating layers mainly governed drug release from the coated pellets with the sensitivity ranging from 23% to 29%. PVP leaching rate and water permeability from EC/PVP film increased with the PVP level, which was perfectly correlated with drug release rate. Additionally, drug release from this formulation was independent of pH of release media or of the paddle mixing speed, but inversely proportional to the osmolality of release media above the physiological range. PMID:24530810

  12. Preparation of an oral acetaminophen film that is expected to improve medication administration: Effect of polyvinylpyrrolidone on physical properties of the film.

    PubMed

    Ito, Ikumi; Ito, Akihiko; Unezaki, Sakae

    2016-01-01

    This study investigated the effect of polyvinylpyrrolidone (PVP) on a film containing carboxymethyl cellulose sodium (CMC) as a matrix to improve surface roughness caused by drug recrystallization. Acetaminophen (AA) was used as the model drug. Recrystallization is a problem encountered during the preparation of films that contain high drug doses, making them difficult to take. A film that does not disintegrate for clinical applications requires a smooth surface, moderate strength and elasticity, and a low level of adhesiveness to facilitate taking of the medication. Addition of PVP to the film formulation made the surface significantly smoother, and it was independent of the compounding method. Smooth films were obtained when the CMC concentration was kept constant and the amount of PVP was increased, but it also increased the adhesiveness and strength, and decreased the elasticity of the films. When high polymer concentration was kept constant and the ratio of CMC and PVP was varied, the films with smaller amounts of PVP tended to have a smoother surface and less adhesiveness. However, when the amount of PVP was reduced, the film strength increased and elasticity decreased. The amount of PVP had a negligible effect on drug dissolution behavior, making it useful for preparation of the AA film. However, it is necessary to determine the compounding method and the PVP load considering the adhesiveness, strength, and elasticity of the films. PMID:27301710

  13. Synthesis and comparative study on the antimicrobial activity of hybrid materials based on silver nanoparticles (AgNps) stabilized by polyvinylpyrrolidone (PVP).

    PubMed

    Bryaskova, Rayna; Pencheva, Daniela; Nikolov, Stanislav; Kantardjiev, Todor

    2011-10-01

    Hybrid materials based on polyvinylpyrrolidone (PVP) with silver nanoparticles (AgNps) were synthesized applying two different strategies based on thermal or chemical reduction of silver ions to silver nanoparticles using PVP as a stabilizer. The formation of spherical silver nanoparticles with diameter ranging from 9 to 16 nm was confirmed by TEM analysis. UV-vis and FTIR spectroscopy were also applied to confirm the successful formation of AgNps. The antibacterial activity of the synthesized AgNPs/PVP against etalon strains of three different groups of bacteria-Staphylococcus aureus (S. aureus; gram-positive bacteria), Escherichia coli (E. coli; gram-negative bacteria), Pseudomonas aeruginosa (P. aeruginosa; non-ferment gram-negative bacteria), as well as against spores of Bacillus subtilis (B. subtilis) was studied. AgNps/PVP were tested for the presence of fungicidal activity against different yeasts and mold such as Candida albicans, Candida krusei, Candida tropicalis, Candida glabrata, and Aspergillus brasiliensis. The hybrid materials showed a strong antimicrobial effect against the tested bacterial and fungal strains and therefore have potential applications in biotechnology and biomedical science. PMID:22837793

  14. Hybridization of polyvinylpyrrolidone to a binary composite of curcumin/α-glucosyl stevia improves both oral absorption and photochemical stability of curcumin.

    PubMed

    Kadota, Kazunori; Okamoto, Daiki; Sato, Hideyuki; Onoue, Satomi; Otsu, Shigeyuki; Tozuka, Yuichi

    2016-12-15

    The tri-component system curcumin/α-glucosyl stevia (Stevia-G)/polyvinylpyrrolidone (PVP) was developed to improve the oral bioavailability and physicochemical properties of curcumin (CUR). The tri-component CUR formulation with Stevia-G and PVP was prepared with freeze-drying. The tri-component CUR system exhibited 13,000-fold higher solubility of CUR than the equilibrium solubility of CUR for 24h, indicating a stable tri-composite structure involving CUR. CUR could be converted into an amorphous form in the presence of Stevia-G and PVP by freeze-drying. The photo-degradation of CUR in the tri-component system was negligible even under an amorphous state of CUR. After oral administration in rats, the oral absorption of the tri-component CUR formulation (20mgCUR/kg) was 6.7-fold higher than that of crystalline CUR. The tri-component CUR formulation would therefore be a promising option to improve physicochemical properties and oral absorption of CUR. PMID:27451233

  15. Development of Ultrafine, Lamellar Structures in Two-Phase {gamma}-TiAl Alloys

    SciTech Connect

    Maziasz, P.J., Liu, C.T.

    1997-12-31

    Processing of two-phase gamma-TiAl alloys (Ti-47Al-2Cr-2Nb or minor modifications thereof) above the alpha-transus temperature (T {sub alpha}) produced unique refined-colony/ultrafine lamellar structures in both powder- and ingot-metallurgy (P/M and I/M, respectively) alloys. These ultrafine lamellar structures consist of fine laths of the gamma and alpha {sub 2} phases, with average interlamellar spacings (lambda {sub Lambda}) of 100-200 nm and alpha {sub 2}-alpha {sub 2} spacings (lambda {sub alpha}) of 200-500 nm, and are dominated by gamma/alpha {sub 2} interfaces. This characteristic microstructure forms by extruding P/M Ti-47Al-2Cr-2Nb alloys above T {sub alpha}, and also forms with finer colony size but slightly coarser fully-lamellar structures by hot-extruding similar I/M alloys. Alloying additions of B and W refine lambda {sub L} and lambda {sub alpha} in both I/M Ti-47Al (cast and heat-treated above T {sub alpha}) or in extruded Ti-47Al-2Cr-2Nb alloys. The ultrafine lamellar structure in the P/M alloy remains stable during heat-treatment at 900 {degrees}C for 2h, but becomes unstable after 4h at 982 {degrees}C; the ultrafine lamellar structure remains relatively stable after aging for {gt}5000 h at 800 {degrees}C. Additions of B+W dramatically improve the coarsening resistance of lambda L and lambda alpha in the I/M Ti-47Al alloys aged for 168 h at 1000{degrees}C. In both the P/M and I/M Ti-47Al-2Cr-2Nb alloys, these refined-colony/ultrafine-lamellar structures correlate with high strength and good ductility at room temperature, and very good strength at high temperatures. While refining the colony size improves the room-temperature ductility, alloys with finer lambda {sub L} are stronger at both room- and high-temperatures. Additions of B+W produce finer as-processed lambda {sub L} and lambda {sub alpha} in I/M TiAl alloys, and stabilize such structures during heat-treatment or aging.

  16. Van der Waal Interactions in Ultrafine Nanocellulose Aerogels

    NASA Astrophysics Data System (ADS)

    Fritch, Byron; Bradley, Derek; Kidd, Tim

    Nanocellulose aerogels have shown an ability to be used in many different applications ranging from oil sponges to conductive materials to possibly a low calorie food substitute. Not much is known about the structural and physical property changes that occur when the composition of the aerogel changes. We studied what properties change when the aerogel amounts change, as well as how sticky the aerogels are and how strong they are. The higher concentrations appeared to have more plate-like structures while the lower concentrations had a more fibrous material. These fibers in the low concentrations had a smaller diameter than a human hair. Only the low concentration aerogels were able to stick to a glass surface in the adhesion test, but were able to support a mass much larger than their own. These low concentrations also would stick to your finger when lightly touched. Preliminary tests show that a concentration that is not too low, but not too high, is best for tensile strength. All concentrations were able to hold many times their own mass. Cellulose should be studied more because it is a renewable material and is easily accessed. Nanocellulose is also not environmentally dangerous allowing it to be used in applications involving humans and the environment like noted above. National Science Foundation Grant DMR-1410496.

  17. Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions. Quarterly technical progress report, July 1, 1991--September 30, 1991

    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.

  18. Liquefaction of coals using ultra-fine particle, unsupported catalysts: In situ generation by rapid expansion of supercritical fluid solutions. Quarterly technical progress report, October 1, 1991--December 31, 1991

    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.

  19. Fiber distributed feedback laser

    NASA Technical Reports Server (NTRS)

    Elachi, C.; Evans, G. A.; Yeh, C. (Inventor)

    1976-01-01

    Utilizing round optical fibers as communication channels in optical communication networks presents the problem of obtaining a high efficiency coupling between the optical fiber and the laser. A laser is made an integral part of the optical fiber channel by either diffusing active material into the optical fiber or surrounding the optical fiber with the active material. Oscillation within the active medium to produce lasing action is established by grating the optical fiber so that distributed feedback occurs.

  20. Fabrication of micro-hollow fiber by electrospinning process in near-critical carbon dioxide

    SciTech Connect

    Okamoto, Koichi; Wahyudiono,; Kanda, Hideki; Goto, Motonobu; Machmudah, Siti; Okubayashi, Satoko; Fukuzato, Ryuichi

    2014-02-24

    Electrospinning is a simple technique that has gained much attention because of its capability and feasibility in the fabrication of large quantities of fibers from polymer with diameters ranging in nano-microscale. These fibers provided high surface area to volume ratios, and it was of considerable interest for many applications, such as nanoparticle carriers in controlled release, scaffolds in tissue engineering, wound dressings, military wear with chemical and biological toxin-resistance, nanofibrous membranes or filters, and electronic sensors. Recently there has been a great deal of progress in the potential applications of hollow fibers in microfluids, photonics, and energy storage. In this work, electrospinning was conducted under high-pressure carbon dioxide (CO{sub 2}) to reduce the viscosity of polymer solution. The experiments were conducted at 313 K and ∼8.0 MPa. Polymer solution containing 5 wt% polymers which prepared in dichloromethane (DCM) with polyvinylpyrrolidone (PVP) to poly-L-lactic acid (PLLA) ratio 80:20 was used as a feed solution. The applied voltage was 15 kV and the distance of nozzle and collector was 8 cm. The morphology and structure of the fibers produced were observed using scanning electron microscopy (SEM). Under pressurized CO{sub 2}, PVP electrospun was produced without bead formation with diameter ranges of 608.50 - 7943.19 nm. These behaviors hold the potential to considerably improve devolatilization electrospinning processes.

  1. TiO2 Fibers: Tunable Polymorphic Phase Transformation and Electrochemical Properties.

    PubMed

    Garcia, Edna; Li, Qiang; Sun, Xing; Lozano, Karen; Mao, Yuanbing

    2015-05-01

    A series of one-dimensional (1 D) nanoparticle-assembled TiO2 fibers with tunable polymorphs were prepared via a novel and large scale ForceSpinning process of titanium tetraisopropoxide (TTIP)/polyvinylpyrrolidone (PVP) precursor fibers followed with a thermal treatment at various calcination temperatures. The thermal and structural transformations were characterized by thermogravimetric analysis/differential scanning calorimetry, scanning electron microscopy, and X-ray diffraction. The influence of polymorphic phase of the TiO2 fibers on the electrochemical performance in neutral aqueous 1 M Na2SO4 electrolyte was investigated. The polymorphic amorphous/anatase/rutile TiO2 fibers prepared at 450 degrees C achieved a highest capacitance of 21.2 F g(-1) (6.61 mF cm(-2)) at a current density of 200 mA g(-1), for which the improved electronic conductivity and activated pseudocapacitance mechanism may be responsible. This work helps bridge the gap between nanoscience and manufacturing. It also makes polymorphism control of functional materials a potential strategy for further improving supercapacitive output of metal oxides. PMID:26505001

  2. Strong fibers

    SciTech Connect

    Li, Che-Yu.

    1991-03-01

    This program was directed to a new and generic approach to the development of new materials with novel and interesting properties, and to the precision fabrication of these materials in one and two-dimensional forms. Advanced deposition processes and microfabrication technology were used to produce fibers and grids of metals, semiconductors, ceramics, and mixtures of controlled composition and structure, and with new and interesting mechanical and physical properties. Deposition processes included electron beam evaporation, co-deposition of mixtures by dual electron beam evaporation, thermal evaporation, sputtering of a single element or compound, sputtering of a single element in a gaseous atmosphere to produce compounds, plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), and selective tungsten chemical vapor deposition (W-CVD). The approach was to use the deposition processes in coordination with patterns generated by optical lithography to produce fibers with transverse dimensions in the micron range, and lengths from less than a millimeter to several centimeters. The approach is also applicable to the production of two-dimensional grids and particulates of controlled sizes and geometries.

  3. Carbon-fiber technology

    NASA Technical Reports Server (NTRS)

    Hansen, C. F.; Parker, J. A.

    1980-01-01

    The state of the art of PAN based carbon fiber manufacture and the science of fiber behavior is surveyed. A review is given of the stabilization by oxidation and the subsequent carbonization of fibers, of the apparent structure of fibers deduced from scanning electron microscopy, from X-ray scattering, and from similarities with soft carbons, and of the known relations between fiber properties and heat treatment temperature. A simplified model is invoked to explain the electrical properties of fibers and recent quantum chemical calculations on atomic clusters are used to elucidate some aspects of fiber conductivity. Some effects of intercalation and oxidative modification of finished fibers are summarized.

  4. Hollow fiber-supported designer ionic liquid sponges for post-combustion CO2 scrubbing

    SciTech Connect

    Lee, JS; Hillesheim, PC; Huang, DK; Lively, RP; Oh, KH; Dai, S; Koros, WJ

    2012-11-30

    A proof of concept study for a new type of carbon capture system is considered for post-combustion CO2 capture based on porous hollow fiber sorbents with ionic liquids sorbed in the cell walls of the fiber. This study proves that delicate morphological features in the open-celled porous wall can be maintained during the infusion process. Mixtures of task specific ionic liquid (i.e. [BMIM][Tf2N]) and superbase (i.e. DBU) were loaded into polyamide-imide (PAI) fibers by a so-called two-step non-solvent infusion protocol. In the protocol, methanol carries ionic liquids into the pore cell walls of hollow fibers and then hexane carries superbase to create an efficient CO2 sorbent. Our ionic liquid/superbase impregnation technique overcomes a serious increase in mass transfer resistance upon reaction with CO2, thereby allowing its large scale utilization for post-combustion CO2 capture. The investigation on the effect of different pore former additives (different molecular weights of polyvinylpyrrolidone, lithium nitrate, and their mixtures) suggested that a large molecular weight of PVP (M-w; 1300k) including dope composition produces highly interconnected open cell pore structures of PAI hollow fibers. Lastly, a lumen side barrier layer was successfully formed on the bore side of neat PAI fibers by using a mixture of Neoprene (R) with crosslinking agents (TSR-633) via a post-treatment process. The lumen layer will enable heat removal from the fiber sorbents during their application in rapid thermal swing cycling processes. (C) 2012 Elsevier Ltd. All rights reserved.

  5. Nuclear microprobe investigation of the penetration of ultrafine zinc oxide into intact and tape-stripped human skin

    NASA Astrophysics Data System (ADS)

    Szikszai, Z.; Kertész, Zs.; Bodnár, E.; Major, I.; Borbíró, I.; Kiss, Á. Z.; Hunyadi, J.

    2010-06-01

    Ultrafine metal oxides, such as titanium dioxide and zinc oxide are widely used in cosmetic and health products like sunscreens. These oxides are potent UV filters and the small particle size makes the product more transparent compared to formulations containing coarser particles. In the present work the penetration of ultrafine zinc oxide into intact and tape-stripped human skin was investigated using nuclear microprobe techniques, such as proton induced X-ray spectroscopy and scanning transmission ion microscopy. Our results indicate that the penetration of ultrafine zinc oxide, in a hydrophobic basis gel with 48 h application time, is limited to the stratum corneum layer of the intact skin. Removing the stratum corneum partially or entirely by tape-stripping did not cause the penetration of the particles into the deeper dermal layers; the zinc particles remained on the surface of the skin.

  6. Perspectives of Using Ultra-Fine Metals as Universal Safe BioStimulators to Get Cattle Breeding Quality Products

    NASA Astrophysics Data System (ADS)

    Polishchuk, S.

    2015-11-01

    We have conducted investigations of ultra-fine metals biological activity with lab non-pedigree white rats, rabbits breed “Soviet chinchilla” and cattle young stock of the black and white breed as the most widely spread in the central part of Russia. One can see the possibility of using microelements of ultra-fine iron, cobalt and copper as cheap, non-toxic and highly effective biological catalyst of biochemical processes in the organism that improve physiological state, morphological and biochemical blood parameters increasing activity of the experimental animals’ ferment systems and their productivity and meat biological value. We have proved the ultra-fine powders safety when adding them to the animals’ diet.

  7. Enhanced strength and electrical conductivity in ultrafine-grained Cu-Cr alloy processed by severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Islamgaliev, R. K.; Nesterov, K. M.; Champion, Y.; Valiev, R. Z.

    2014-08-01

    The influence of severe plastic deformation on strength and electrical conductivity in the Cu-Cr copper alloy has been studied. Microstructure of ultrafine-grained samples was investigated by transmission electron microscopy and X-ray diffraction with special attention on precipitation of small chromium particles after various thermal treatments. Effect of dynamic precipitation leading to enhancement of strength and electrical conductivity was observed. It is shown that ultrafine-grained samples enable to demonstrate the combination of enhanced thermal stability up to 500°C, high ultimate tensile strength of 790-840 MPa and enhanced electrical conductivity of 81-85% IACS. The contributions of grain boundaries and precipitates to enhanced properties of ultrafine-grained copper alloy are discussed.

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

    SciTech Connect

    Not Available

    1991-08-01

    The program objective is to generate ultra-fine catalyst particles (20 to 400 {Angstrom} in size) and quantify their potential for improving coal dissolution in the solubilization stage of two-stage catalytic-catalytic liquefaction systems. It has been shown that catalyst activity increases significantly with decreasing particle size for particle sizes in the submicron range. Ultra-fine catalyst particle generation will be accomplished using a novel two-step process. First, the severe conditions produced by a supercritical fluid (e.g., supercritical H{sub 2}O or CO{sub 2}) will be used to dissolve suitable catalyst compounds (e.g., Fe{sub 2}O{sub 3}, FeS{sub 2}, and/or Fe(CO){sub 5}). Sulfur containing compounds may be added to the supercritical solvent during catalyst dissolution to enhance the catalytic activity of the resulting ultra-fine, iron based, catalyst particles.

  9. Graphite to ultrafine nanocrystalline diamond phase transition model and growth restriction mechanism induced by nanosecond laser processing

    NASA Astrophysics Data System (ADS)

    Ren, X. D.; Liu, R.; Zheng, L. M.; Ren, Y. P.; Hu, Z. Z.; He, H.

    2015-10-01

    To have a clear insight into nanocrystal growth from graphite to diamond upon high energy pulsed laser irradiation of graphite suspension, synthesis of ultrafine nanocrystalline diamonds with laser energy set up from 0.3 J to 12 J, repetition rate of 10 Hz has been studied. The method allows synthesizing ultrafine nanocrystalline particles continuously at the ambient temperature and normal pressure. The particle size is shown independent of laser energy, which is ultrafine and ranges in 2-6 nm. The theoretical grown size of nano-diamonds is found in well agreement with the experiment results. Four kinds of production were found: nano-diamond, spherical carbon nano-particles, flocculent amorphous carbon, and graphene nano-ribbon rolls. A solid-vapor-plasma-liquid coexistence model describing phase transition from graphite to diamond induced by nanosecond laser processing was proposed. Graphene nano-ribbon rolls might be the intermediate phase in the conversion from graphite to diamond.

  10. An investigation into the influence of drug-polymer interactions on the miscibility, processability and structure of polyvinylpyrrolidone-based hot melt extrusion formulations.

    PubMed

    Chan, Siok-Yee; Qi, Sheng; Craig, Duncan Q M

    2015-12-30

    While hot melt extrusion is now established within the pharmaceutical industry, the prediction of miscibility, processability and structural stability remains a pertinent issue, including the issue of whether molecular interaction is necessary for suitable performance. Here we integrate the use of theoretical and experimental drug-polymer interaction assessment with determination of processability and structure of dispersions in two polyvinylpyrrolidone-based polymers (PVP and PVP vinyl acetate, PVPVA). Caffeine and paracetamol were chosen as model drugs on the basis of their differing hydrogen bonding potential with PVP. Solubility parameter and interaction parameter calculations predicted a greater miscibility for paracetamol, while ATR-FTIR confirmed the hydrogen bonding propensity of the paracetamol with both polymers, with little interaction detected for caffeine. PVP was found to exhibit greater interaction and miscibility with paracetamol than did PVPVA. It was noted that lower processing temperatures (circa 40°C below the Tg of the polymer alone and Tm of the crystalline drug) and higher drug loadings with associated molecular dispersion up to 50% w/w were possible for the paracetamol dispersions, although molecular dispersion with the non-interactive caffeine was noted at loadings up to 20% w./w. A lower processing temperature was also noted for caffeine-loaded systems despite the absence of detectable interactions. The study has therefore indicated that theoretical and experimental detection of miscibility and drug-polymer interactions may lead to insights into product processing and extrudate structure, with direct molecular interaction representing a helpful but not essential aspect of drug-polymer combination prediction. PMID:26428633

  11. Na0.44MnO2 with very fast sodium diffusion and stable cycling synthesized via polyvinylpyrrolidone-combustion method

    NASA Astrophysics Data System (ADS)

    Dai, Kehua; Mao, Jing; Song, Xiangyun; Battaglia, Vince; Liu, Gao

    2015-07-01

    Na0.44MnO2 is a very promising cathode material in sodium-ion batteries for large-scale application. Na0.44MnO2 with very fast sodium diffusion and stable cycling is prepared by polyvinylpyrrolidone (PVP)-combustion method. X-ray diffraction, scanning electron microscope and high-resolution transmission electron microscopy are conducted to explore the morphology and structure. Electrochemical performance of the samples is examined in coin cells with sodium foil anode and nonaqueous electrolyte. The Na0.44MnO2 sample synthesized at 900 °C (NMO-900) discharges the highest capacity of 122.9 mAh g-1 at C/5. A fast-rate-test technique developed by Newman et al. is adopted for quick determination of the rate capability. All the samples exhibit good rate capability while the NMO-900 shows the best. Normal rate test result supports the reliability of the fast rate test. Even at 20C charge and discharge rate, the NMO-900 delivers 99 mAh g-1 capacity. The chemical diffusion coefficient of sodium is measured to be around 3 × 10-12 cm2 s-1 by potential intermittent titration technique (PITT). The cycling stability is also very good. The capacity retention after 100 cycles at 1C is 87.9% and the capacity still remains 82.9% even after 700 cycles at 10C. During cycling the coulombic efficiency keeps near 99.8%.

  12. Preparation and characterization of chitosan-Polyethylene glycol-polyvinylpyrrolidone-coated superparamagnetic iron oxide nanoparticles as carrier system: Drug loading and in vitro drug release study.

    PubMed

    Prabha, G; Raj, V

    2016-05-01

    In the present research work, the anticancer drug "curcumin" is loaded with Chitosan (CS)-polyethylene glycol (PEG)-polyvinylpyrrolidone (PVP) (CS-PEG-PVP) polymer nanocomposites coated with superparamagnetic iron oxide (Fe3 O4 ) nanoparticles. The system can be used for targeted and controlled drug delivery of anticancer drugs with reduced side effects and greater efficiency. The prepared nanoparticles were characterized by Fourier transmission infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Curcumin drug-loaded Fe3 O4 -CS, Fe3 O4 -CS- PEG and Fe3 O4 -CS-PEG-PVP nanoparticles exhibited the mean particle size in the range of 183 - 390 nm with a zeta potential value of 26 mV-41 mV as measured using Malvern Zetasizer. The encapsulation efficiency, loading capacity and in-vitro drug release behaviour of curcumin drug-loaded Fe3 O4 -CS, Fe3 O4 -CS-PEG, and Fe3 O4 -CS-PEG-PVP nanoparticles were studied using UV spectrophotometer. Besides, the cytotoxicity of the prepared nanoparticles using MTT assay was also studied. The curcumin drug release was examined at different pH medium (4.5 and 7.4) and temperature (37°C and 45°C), and it was proved that the drug release depends upon the pH medium and temperature in addition to the nature of matrix. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 808-816, 2016. PMID:26996397

  13. The polyvinylpyrrolidone functionalized rGO/Bi2S3 nanocomposite as a near-infrared light-responsive nanovehicle for chemo-photothermal therapy of cancer.

    PubMed

    Dou, Ruixia; Du, Zhen; Bao, Tao; Dong, Xinghua; Zheng, Xiaopeng; Yu, Miao; Yin, Wenyan; Dong, Binbin; Yan, Liang; Gu, Zhanjun

    2016-06-01

    Recently, a combination of chemotherapy with photothermal therapy (PTT) has received great attention for the construction of a near infrared (NIR)-controlled drug-delivery system for synergistic treatment of cancer, ultimately resulting in the enhancement of the therapeutic efficacy of anticancer drugs. Here, we developed a novel system for synergistic cancer therapy based on bismuth sulfide (Bi2S3) nanoparticle-decorated graphene functionalized with polyvinylpyrrolidone (PVP) (named PVP-rGO/Bi2S3). The as-prepared PVP-rGO/Bi2S3 nanocomposite has a high storage capacity for anticancer drugs (∼500% for doxorubicin (DOX)) and simultaneously has perfect photothermal conversion efficiency in the NIR region. The results of the in vitro accumulative drug release test manifests that the PVP-rGO/Bi2S3 nanocomposite could be applied as a dual pH- and NIR-responsive nanotherapeutic carrier for the controlled release of DOX from DOX-loaded PVP-rGO/Bi2S3 (PVP-rGO/Bi2S3@DOX). Moreover, the treatment of both cancer cells (including Hela, MCF-7, HepG2 and BEL-7402 cells) and BEL-7402 tumor-bearing mice with the PVP-rGO/Bi2S3@DOX complex followed by NIR laser irradiation produces significantly greater inhibition of cancer cell growth than the treatment with NIR irradiation alone or DOX alone, exhibiting a synergistic antitumor effect. Furthermore, due to the obvious NIR and X-ray absorption ability, the PVP-rGO/Bi2S3 nanocomposite could be employed as a dual-modal contrast agent for both photoacoustic tomography and X-ray computed tomography imaging. In addition to the good biocompatibility, the PVP-rGO/Bi2S3 nanocomposite paves a potential way for the fabrication of theranostic agents for dual-modal imaging-guided chemo-photothermal combined cancer therapy. PMID:27203525

  14. Investigation and Evaluation of an in Situ Interpolymer Complex of Carbopol with Polyvinylpyrrolidone as a Matrix for Gastroretentive Tablets of Ranitidine Hydrochloride.

    PubMed

    Yusif, Rehab Mohammad; Abu Hashim, Irhan Ibrahim; Mohamed, Elham Abdelmonem; El Rakhawy, Mohamed Magdy

    2016-01-01

    Carbopol (CP) is a biocompatible bioadhesive polymer used as a matrix for gastroretentive (GR) tablets, however, its rapid hydration shortens its bioadhesion and floating when incorporated in effervescent formulae. The interpolymer complexation of CP with polyvinylpyrrolidone (PVP) significantly reduced the excessive hydration of CP, prolonging floating and maintaining the mucoadhesiveness. In early attempts, a lengthy process was followed to prepare such an interpolymer complex. In this study, an in situ interpolymer complexation between CP and two grades of PVP (K25 and K90) in 0.1 N HCl was investigated and characterized by Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Hence, directly compressed GR tablets of different combinations of PVP and CP with sodium bicarbonate (SB) as an effervescent agent were examined for prolonged gastroretention and sustained release of ranitidine hydrochloride (RHCl) as a model drug. Tablets were evaluated for in vitro buoyancy, bioadhesiveness, swelling, and drug release in 0.1 N HCl. All GR tablets containing PVP-CP combinations achieved more prolonged floating (>24 h) than CP tablets (5.2 h). Their bioadhesiveness, swelling, and drug release were dependent on the PVP molecular weight and its ratio to CP. Drug release profiles of all formulae followed non-Fickian diffusion. Formula containing the PVP K90-CP combination at a respective ratio of 1 : 3 (P90C13) was a promising system, exhibiting good floating and bioadhesive properties as well as sustained drug release. Abdominal X-ray imaging of P90C13 formula, loaded with barium sulfate, in six healthy volunteers showed a mean gastric retention period of 6.8±0.3 h. PMID:26726743

  15. Chlorin e6 – polyvinylpyrrolidone mediated photosensitization is effective against human non-small cell lung carcinoma compared to small cell lung carcinoma xenografts

    PubMed Central

    Chin, William WL; Heng, Paul WS; Olivo, Malini

    2007-01-01

    Background Photodynamic therapy (PDT) is an effective local cancer treatment that involves light activation of a photosensitizer, resulting in oxygen-dependent, free radical-mediated cell death. Little is known about the comparative efficacy of PDT in treating non-small cell lung carcinoma (NSCLC) and small cell lung carcinoma (SCLC), despite ongoing clinical trials treating lung cancers. The present study evaluated the potential use of chlorin e6 – polyvinylpyrrolidone (Ce6-PVP) as a multimodality photosensitizer for fluorescence detection and photodynamic therapy (PDT) on NSCLC and SCLC xenografts. Results Human NSCLC (NCI-H460) and SCLC (NCI-H526) tumor cell lines were used to establish tumor xenografts in the chick chorioallantoic membrane (CAM) model as well as in the Balb/c nude mice. In the CAM model, Ce6-PVP was applied topically (1.0 mg/kg) and fluorescence intensity was charted at various time points. Tumor-bearing mice were given intravenous administration of Ce6-PVP (2.0 mg/kg) and laser irradiation at 665 nm (fluence of 150 J/cm2 and fluence rate of 125 mW/cm2). Tumor response was evaluated at 48 h post PDT. Studies of temporal fluorescence pharmacokinetics in CAM tumor xenografts showed that Ce6-PVP has a selective localization and a good accuracy in demarcating NSCLC compared to SCLC from normal surrounding CAM after 3 h post drug administration. Irradiation at 3 h drug-light interval showed greater tumor necrosis against human NSCLC xenografts in nude mice. SCLC xenografts were observed to express resistance to photosensitization with Ce6-PVP. Conclusion The formulation of Ce6-PVP is distinctly advantageous as a diagnostic and therapeutic agent for fluorescence diagnosis and PDT of NSCLC. PMID:18053148

  16. Urban and rural ultrafine (PM 0.1) particles in the Helsinki area

    NASA Astrophysics Data System (ADS)

    Pakkanen, Tuomo A.; Kerminen, Veli-Matti; Korhonen, Christina H.; Hillamo, Risto E.; Aarnio, Päivi; Koskentalo, Tarja; Maenhaut, Willy

    In June 1996-June 1997 Berner low-pressure impactors were used at an urban and at a rural site in the Helsinki area for sampling ultrafine particles (UFP, PM 0.1). Ten sample pairs, each pair measured simultaneously, were collected in the size range of 0.03-15 μm of particle aerodynamic diameter. More than 40 chemical components were measured. Surprisingly, the average UFP mass concentration was higher at the rural site (520 ng/m 3) than at the urban site (490 ng/m 3). The average chemical composition of UFP was similar at the two sites. The most abundant of the measured components were sulphate (32 and 40 ng/m 3 for the urban and rural sites, respectively), ammonium (22 and 25 ng/m 3), nitrate (4 and 11 ng/m 3) and the Ca 2+ ion (5 and 7 ng/m 3). The most important metals at both sites were Ca, Na, Fe, K and Zn with concentrations between 0.7 and 5 ng/m 3. Of the heavy metals, Ni, V, Cu, and Pb were important with average ultrafine concentrations between about 0.1 and 0.2 ng/m 3. Also the organic anions oxalate (urban 2.1 ng/m 3 and rural 1.9 ng/m 3) and methanesulphonate (1.3 and 1.7 ng/m 3) contributed similarly at both sites. The measured species accounted for only about 15-20% of the total ultrafine mass. The fraction that was not measured includes mainly carbonaceous material and water. It was estimated that the amount of water was about 10% (50 ng/m 3) and that of carbonaceous material about 70% (350 ng/m 3) at both sites. Aitken modes were observed for most components with the average mass mean mode diameters being between about 0.06 and 0.12 μm. The average concentrations in the Aitken mode differed clearly from those in the UFP for several components. The average contribution of ultrafine mass to the fine particle mass (PM 2.5) was about 7% at the urban site and 8.5% at the rural site. At both sites the contribution of ultrafine to fine was especially high for Se, Ag, B, and Ni (10-20%) and at the rural site also for Co (20%), Ca 2+ (16%) and Mo (11

  17. Resistance spot welding of ultra-fine grained steel sheets produced by constrained groove pressing: Optimization and characterization

    SciTech Connect

    Khodabakhshi, F.; Kazeminezhad, M. Kokabi, A.H.

    2012-07-15

    Constrained groove pressing as a severe plastic deformation method is utilized to produce ultra-fine grained low carbon steel sheets. The ultra-fine grained sheets are joined via resistance spot welding process and the characteristics of spot welds are investigated. Resistance spot welding process is optimized for welding of the sheets with different severe deformations and their results are compared with those of as-received samples. The effects of failure mode and expulsion on the performance of ultra-fine grained sheet spot welds have been investigated in the present paper and the welding current and time of resistance spot welding process according to these subjects are optimized. Failure mode and failure load obtained in tensile-shear test, microhardness, X-ray diffraction, transmission electron microscope and scanning electron microscope images have been used to describe the performance of spot welds. The region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. The results show that optimum welding parameters (welding current and welding time) for ultra-fine grained sheets are shifted to lower values with respect to those for as-received specimens. In ultra-fine grained sheets, one new region is formed named recrystallized zone in addition to fusion zone, heat affected zone and base metal. It is shown that microstructures of different zones in ultra-fine grained sheets are finer than those of as-received sheets. - Highlights: Black-Right-Pointing-Pointer Resistance spot welding process is optimized for joining of UFG steel sheets. Black-Right-Pointing-Pointer Optimum welding current and time are decreased with increasing the CGP pass number. Black-Right-Pointing-Pointer Microhardness at BM, HAZ, FZ and recrystallized zone is enhanced due to CGP.

  18. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    SciTech Connect

    James K. Neathery; Gary Jacobs; Amitava Sarkar; Burtron H. Davis

    2005-09-30

    In this reporting period, a study of ultra-fine iron catalyst filtration was initiated to study the behavior of ultra-fine particles during the separation of Fischer-Tropsch Synthesis (FTS) liquids filtration. The overall focus of the program is with slurry-phase FTS in slurry bubble column reactor systems. Hydrocarbon products must be separated from catalyst particles before being removed from the reactor system. An efficient wax product/catalyst separation system is a key factor for optimizing operating costs for iron-based slurry-phase FTS. Previous work has focused on catalyst particle attrition and the formation of ultra-fine iron carbide and/or carbon particles. With the current study, we are investigating how the filtration properties are affected by these chemical and physical changes of the catalyst slurry during activation/synthesis. The change of particle size during the slurry-phase FTS has monitored by withdrawing catalyst sample at different TOS. The measurement of dimension of the HRTEM images of samples showed a tremendous growth of the particles. Carbon rims of thickness 3-6 nm around the particles were observed. This growth in particle size was not due to carbon deposition on the catalyst. A conceptual design and operating philosophy was developed for an integrated wax filtration system for a 4 liter slurry bubble column reactor to be used in Phase II of this research program. The system will utilize a primary inertial hydroclone followed by a Pall Accusep cross-flow membrane. Provisions for cleaned permeate back-pulsing will be included to as a flux maintenance measure.

  19. Detection and formation mechanism of micro-defects in ultrafine pitch Cu—Cu direct bonding

    NASA Astrophysics Data System (ADS)

    Zi-Yu, Liu; Jian, Cai; Qian, Wang; Yu, Chen

    2016-01-01

    In this paper, Cu-Cu interconnects with ultrafine pad pitches of 6 μm, 8 μm, and 15 μm are implemented on the 12 inch wafers by a direct bonding process. Defects are not found by traditional non-destructive (NDT) c-mode scanning acoustic microscopy (c-SAM). However, cross sectional observation of bonding interfaces reveals that micro-defects such as micro seams are located at SiO2 bonding interfaces. In order to examine the micro-defects in the ultra-fine pitch direct bonding process by the NDT technology, a novel “defect-enlarged approach” is proposed. The bonded dies are first annealed in an N2 oven at 300 °C for a few hours and then cooled quickly in air. The c-SAM scanning images show large defects at the place where nothing can be detected by c-SAM before this treatment. Cross sectional observation of the bonding interfaces indicates that these defects consist of large size micro seams at the SiO2 bonding interface, especially near Cu pads with an ultrafine pitch of 6 μm. However, these large defects disappear after several hours at room temperature, observed by c-SAM. It is inferred that the disappearance of these defects inspected by the “defect-enlarged approach” results from the combination of intrinsic micro seams and “weak” bonds in the silicon oxide layer. Then the underlying physical mechanism of these micro-defects is proposed, which is influenced by Cu pad surface topology and bonding models. Project supported by the National Natural Science Foundation of China (Grant No. 61274111) and the National Basic Research Program of China (Grant No. 2015CB057205).

  20. Ultrafine Particulate Dispersed High-Temperature Coatings by Hybrid Spray Process

    NASA Astrophysics Data System (ADS)

    Mohanty, P. S.; Roche, A. D.; Guduru, R. K.; Varadaraajan, V.

    2010-01-01

    Oxide dispersion strengthened alloys (ODS), although not commonly used in coating applications, have long been used for high-temperature structural applications due to their superior creep properties. In this paper, we present the design, synthesis, and characterization of a new class of functionally engineered high-temperature coatings in which ultrafine oxide particulates are dispersed in the matrix alloy to achieve superior creep resistance along with improved high-temperature corrosion and erosion resistance. These coatings were fabricated using a novel technique called “hybrid spray process”. Hybrid spray technique combines arc spray and high-velocity oxy fuel (HVOF) spray processes; the metallic matrix alloys are fused by the wire arcing component of the process, whereas the ultrafine particles are synthesized in-flight by the HVOF component from liquid precursors. These particulate dispersed high-temperature composite coatings were fabricated using liquid precursors for SiO2, Cr2O3, Al2O3, and wire feed stock of 55/45 NiCr, in one step. The coatings were then characterized using electron microscopy (SEM/TEM) and thermogravimetric analysis (TGA). High-temperature erosion, oxidation, and corrosion performance of these coatings were also evaluated and compared with 304 stainless steel, arc sprayed NiCr coatings as well as Alloy 625 overlay cladding. The hybrid spray process produced dense coatings with uniform dispersion of the ultrafine oxide particles. Further, these coatings also demonstrated superior corrosion, erosion, and oxidation resistance; SiO2 particulate dispersion being most effective in terms of high-temperature corrosion resistance.

  1. Ultrafine particle emission from incinerators: the role of the fabric filter.

    PubMed

    Buonanno, G; Scungio, M; Stabile, L; Tirler, W

    2012-01-01

    Incinerators are claimed to be responsible of particle and gaseous emissions: to this purpose Best Available Techniques (BAT) are used in the flue-gas treatment sections leading to pollutant emission lower than established threshold limit values. As regard particle emission, only a mass-based threshold limit is required by the regulatory authorities. However; in the last years the attention of medical experts moved from coarse and fine particles towards ultrafine particles (UFPs; diameter less than 0.1 microm), mainly emitted by combustion processes. According to toxicological and epidemiological studies, ultrafine particles could represent a risk for health and environment. Therefore, it is necessary to quantify particle emissions from incinerators also to perform an exposure assessment for the human populations living in their surrounding areas. A further topic to be stressed in the UFP emission from incinerators is the particle filtration efficiency as function of different flue-gas treatment sections. In fact, it could be somehow important to know which particle filtration method is able to assure high abatement efficiency also in terms of UFPs. To this purpose, in the present work experimental results in terms of ultrafine particle emissions from several incineration plants are reported. Experimental campaigns were carried out in the period 2007-2010 by measuring UFP number distributions and total concentrations at the stack of five plants through condensation particle counters and mobility particle sizer spectrometers. Average total particle number concentrations ranging from 0.4 x 10(3) to 6.0 x 10(3) particles cm(-3) were measured at the stack of the analyzed plants. Further experimental campaigns were performed to characterize particle levels before the fabric filters in two of the analyzed plants in order to deepen their particle reduction effect; particle concentrations higher than 1 x 10(7) particles cm(-3) were measured, leading to filtration

  2. Children exposure to indoor ultrafine particles in urban and rural school environments.

    PubMed

    Cavaleiro Rufo, João; Madureira, Joana; Paciência, Inês; Slezakova, Klara; Pereira, Maria do Carmo; Aguiar, Lívia; Teixeira, João Paulo; Moreira, André; Oliveira Fernandes, Eduardo

    2016-07-01

    Extended exposure to ultrafine particles (UFPs) may lead to consequences in children due to their increased susceptibility when compared to older individuals. Since children spend in average 8 h/day in primary schools, assessing the number concentrations of UFPs in these institutions is important in order to evaluate the health risk for children in primary schools caused by indoor air pollution. Thus, the purpose of this study was to assess and determine the sources of indoor UFP number concentrations in urban and rural Portuguese primary schools. Indoor and outdoor ultrafine particle (UFP) number concentrations were measured in six urban schools (US) and two rural schools (RS) located in the north of Portugal, during the heating season. The mean number concentrations of indoor UFPs were significantly higher in urban schools than in rural ones (10.4 × 10(3) and 5.7 × 10(3) pt/cm(3), respectively). Higher UFP levels were associated with higher squared meters per student, floor levels closer to the ground, chalk boards, furniture or floor covering materials made of wood and windows with double-glazing. Indoor number concentrations of ultrafine-particles were inversely correlated with indoor CO2 levels. In the present work, indoor and outdoor concentrations of UFPs in public primary schools located in urban and rural areas were assessed, and the main sources were identified for each environment. The results not only showed that UFP pollution is present in augmented concentrations in US when compared to RS but also revealed some classroom/school characteristics that influence the concentrations of UFPs in primary schools. PMID:27040535

  3. Aerosol number size distributions over a coastal semi urban location: Seasonal changes and ultrafine particle bursts.

    PubMed

    Babu, S Suresh; Kompalli, Sobhan Kumar; Moorthy, K Krishna

    2016-09-01

    Number-size distribution is one of the important microphysical properties of atmospheric aerosols that influence aerosol life cycle, aerosol-radiation interaction as well as aerosol-cloud interactions. Making use of one-yearlong measurements of aerosol particle number-size distributions (PNSD) over a broad size spectrum (~15-15,000nm) from a tropical coastal semi-urban location-Trivandrum (Thiruvananthapuram), the size characteristics, their seasonality and response to mesoscale and synoptic scale meteorology are examined. While the accumulation mode contributed mostly to the annual mean concentration, ultrafine particles (having diameter <100nm) contributed as much as 45% to the total concentration, and thus constitute a strong reservoir, that would add to the larger particles through size transformation. The size distributions were, in general, bimodal with well-defined modes in the accumulation and coarse regimes, with mode diameters lying in the range 141 to 167nm and 1150 to 1760nm respectively, in different seasons. Despite the contribution of the coarse sized particles to the total number concentration being meager, they contributed significantly to the surface area and volume, especially during transport of marine air mass highlighting the role of synoptic air mass changes. Significant diurnal variation occurred in the number concentrations, geometric mean diameters, which is mostly attributed to the dynamics of the local coastal atmospheric boundary layer and the effect of mesoscale land/sea breeze circulation. Bursts of ultrafine particles (UFP) occurred quite frequently, apparently during periods of land-sea breeze transitions, caused by the strong mixing of precursor-rich urban air mass with the cleaner marine air mass; the resulting turbulence along with boundary layer dynamics aiding the nucleation. These ex-situ particles were observed at the surface due to the transport associated with boundary layer dynamics. The particle growth rates from

  4. Ultrafine particles, and PM 2.5 generated from cooking in homes

    NASA Astrophysics Data System (ADS)

    Wan, Man-Pun; Wu, Chi-Li; Sze To, Gin-Nam; Chan, Tsz-Chun; Chao, Christopher Y. H.

    2011-11-01

    Exposure to airborne particulate matters (PM) emitted during cooking can lead to adverse health effects. An understanding of the exposure to PM during cooking at home provides a foundation for the quantification of possible health risks. The concentrations of airborne particles covering the ultrafine (14.6-100 nm) and accumulation mode (100-661.2 nm) size ranges and PM 2.5 (airborne particulate matters smaller than 2.5 μm in diameter) during and after cooking activities were measured in 12 naturally ventilated, non-smoking homes in Hong Kong, covering a total of 33 cooking episodes. The monitored homes all practiced Chinese-style cooking. Cooking elevated the average number concentrations of ultrafine particles (UFPs) and accumulation mode particles (AMPs) by 10 fold from the background level in the living room and by 20-40 fold in the kitchen. PM 2.5 mass concentrations went up to the maximum average of about 160 μg m -3 in the kitchen and about 60 μg m -3 in the living room. Cooking emitted particles dispersed quickly from the kitchen to the living room indicating that the health impact is not limited to occupants in the kitchen. Particle number and mass concentrations remained elevated for 90 min in the kitchen and for 60 min in the living room after cooking. Particles in cooking emissions were mainly in the ultrafine size range in terms of the number count while AMPs contributed to at least 60% of the surface area concentrations in the kitchen and 73% in the living room. This suggests that AMPs could still be a major health concern since the particle surface area concentration is suggested to have a more direct relationship with inhalation toxicity than with number concentration. Particle number concentration (14.6-661.2 nm) in the living room was about 2.7 times that in the outdoor environment, suggesting that better ventilation could help reduce exposure.

  5. Combustion-Derived Ultrafine Particles Transport Organic Toxicants to Target Respiratory Cells

    PubMed Central

    Penn, Arthur; Murphy, Gleeson; Barker, Steven; Henk, William; Penn, Lynn

    2005-01-01

    Epidemiologic evidence supports associations between inhalation of fine and ultrafine ambient particulate matter [aerodynamic diameter ≤ 2.5 μm (PM2.5)] and increases in cardiovascular/respiratory morbidity and mortality. Less attention has been paid to how the physical and chemical characteristics of these particles may influence their interactions with target cells. Butadiene soot (BDS), produced during combustion of the high-volume petrochemical 1,3-butadiene, is rich in polynuclear aromatic hydrocarbons (PAHs), including known carcinogens. We conducted experiments to characterize BDS with respect to particle size distribution, assembly, PAH composition, elemental content, and interaction with respiratory epithelial cells. Freshly generated, intact BDS is primarily (> 90%) PAH-rich, metals-poor (nickel, chromium, and vanadium concentrations all < 1 ppm) PM2.5, composed of uniformly sized, solid spheres (30–50 nm) in aggregated form. Cells of a human bronchial epithelial cell line (BEAS-2B) exhibit sequential fluorescent responses—a relatively rapid (~ 30 min), bright but diffuse fluorescence followed by the slower (2–4 hr) appearance of punctate cytoplasmic fluorescence—after BDS is added to medium overlying the cells. The fluorescence is associated with PAH localization in the cells. The ultrafine BDS particles move down through the medium to the cell membrane. Fluorescent PAHs are transferred from the particle surface to the cell membrane, cross the membrane into the cytosol, and appear to accumulate in lipid vesicles. There is no evidence that BDS particles pass into the cells. The results demonstrate that uptake of airborne ultrafine particles by target cells is not necessary for transfer of toxicants from the particles to the cells. PMID:16079063

  6. Mechanical properties and radiation tolerance of ultrafine grained and nanocrystalline metals

    NASA Astrophysics Data System (ADS)

    Sun, Cheng

    Austenitic stainless steels are commonly used in nuclear reactors and have been considered as potential structural materials in fusion reactors due to their excellent corrosion resistance, good creep and fatigue resistance at elevated temperatures, but their relatively low yield strength and poor radiation tolerance hinder their applications in high dose radiation environments. High angle grain boundaries have long been postulated as sinks for radiation-induced defects, such as bubbles, voids, and dislocation loops. Here we provide experimental evidence that high angle grain boundaries can effectively remove radiation-induced defects. The equal channel angular pressing (ECAP) technique was used to produce ultrafine grained Fe-Cr-Ni alloy. Mechanical properties of the alloy were studied at elevated temperature by tensile tests and in situ neutron scattering measurements. Enhanced dynamic recovery process at elevated temperature due to dislocation climb lowers the strain hardening rate and ductility of ultrafine grained Fe-Cr-Ni alloy. Thermal stability of the ultrafine grained Fe-Cr-Ni alloy was examined by ex situ annealing and in situ heating within a transmission electron microscope. Abnormal grain growth at 827 K (600°C) is attributed to deformation-induced martensite, located at the triple junctions of grains. Helium ion irradiation studies on Fe-Cr-Ni alloy show that the density of He bubbles, dislocation loops, as well as irradiation hardening are reduced by grain refinement. In addition, we provide direct evidence, via in situ Kr ion irradiation within a transmission electron microscope, that high angle grain boundaries in nanocrystalline Ni can effectively absorb irradiation-induced dislocation loops and segments. The density and size of dislocation loops in irradiated nanocrystalline Ni were merely half of those in irradiated coarse grained Ni. The results imply that irradiation tolerance in bulk metals can be effectively enhanced by microstructure

  7. Influential parameters on ultrafine particle concentration downwind at waste-to-energy plants.

    PubMed

    Scungio, Mauro; Buonanno, Giorgio; Arpino, Fausto; Ficco, Giorgio

    2015-04-01

    A numerical investigation on the parameters influencing the ultrafine particle concentrations downwind an incinerator plant has been carried out on a three-dimensional full scale model. The simulation was based on a modified version of the k-ε turbulence model in order to take into account the thermal buoyancy effect of the plume, and reproducing a stable and neutral atmospheric boundary layer by setting appropriate values of velocity, turbulent kinetic energy and turbulent dissipation rate. The ability of the model to reproduce and maintain a stable atmospheric boundary layer was evaluated by analyzing the turbulent characteristics of the flow along the domain. A parametric analysis made on the basis of different plant operational, environmental, and flue gas treatment parameters was carried out in order to evaluate the impact of incinerator plants on the background concentration of ultrafine particles. The evaluation was made at 5 km downwind the chimney in a breathable area, showing that the most significant impact is due to the flue gas treatment section, with a variation on the background concentration up to 370% for a plant hypothetically working without controls on ultrafine particles emission. Operational and environmental parameters determine variations of the concentrations ranging from 1.62% to 4.48% for the lowest and highest chimney, from 1.41% to 4.52% for the lowest and highest wind speed and from 2.48% to 4.5% for the lowest and highest flue gas velocity, respectively. In addition, plume rise evaluation was carried out as a function of wind speed and flue gas velocity from the chimney. PMID:25670165

  8. Ultrafine particles cause cytoskeletal dysfunctions in macrophages: role of intracellular calcium

    PubMed Central

    Möller, Winfried; Brown, David M; Kreyling, Wolfgang G; Stone, Vicki

    2005-01-01

    Background Particulate air pollution is reported to cause adverse health effects in susceptible individuals. Since most of these particles are derived form combustion processes, the primary composition product is carbon with a very small diameter (ultrafine, less than 100 nm in diameter). Besides the induction of reactive oxygen species and inflammation, ultrafine particles (UFP) can cause intracellular calcium transients and suppression of defense mechanisms of alveolar macrophages, such as impaired migration or phagocytosis. Methods In this study the role of intracellular calcium transients caused by UFP was studied on cytoskeleton related functions in J774A.1 macrophages. Different types of fine and ultrafine carbon black particles (CB and ufCB, respectively), such as elemental carbon (EC90), commercial carbon (Printex 90), diesel particulate matter (DEP) and urban dust (UD), were investigated. Phagosome transport mechanisms and mechanical cytoskeletal integrity were studied by cytomagnetometry and cell viability was studied by fluorescence microscopy. Macrophages were exposed in vitro with 100 and 320 μg UFP/ml/million cells for 4 hours in serum free medium. Calcium antagonists Verapamil, BAPTA-AM and W-7 were used to block calcium channels in the membrane, to chelate intracellular calcium or to inhibit the calmodulin signaling pathways, respectively. Results Impaired phagosome transport and increased cytoskeletal stiffness occurred at EC90 and P90 concentrations of 100 μg/ml/million cells and above, but not with DEP or UD. Verapamil and W-7, but not BAPTA-AM inhibited the cytoskeletal dysfunctions caused by EC90 or P90. Additionally the presence of 5% serum or 1% bovine serum albumin (BSA) suppressed the cytoskeletal dysfunctions. Cell viability showed similar results, where co-culture of ufCB together with Verapamil, W-7, FCS or BSA produced less cell dead compared to the particles only. PMID:16202162

  9. Fabrication of ultra-fine grained aluminium tubes by RTES technique

    SciTech Connect

    Jafarzadeh, H. Abrinia, K.

    2015-04-15

    Recently, repetitive tube expansion and shrinking have been exploited as a means for producing ultra-fine grained and nano-crystalline microstructures for magnesium alloy tubes. This method includes two different half-cycles and was based on pressing a tubular part through an angular channel die with two shear zones. Since the aluminium alloys are the most widely used materials in industries, in this study, repetitive tube expansion and shrinking as a new severe plastic deformation technique was applied to commercially pure aluminium for fabricating ultra-fine grained aluminium tubes for the first time and the ability of this process in significant grain refinement is determined even after single cycle. Transmission electron microscopy and X-ray diffraction were used to evaluate the microstructure of the repetitive tube expansion and shrinking processed materials and the examinations showed ultra-fine grains with the average grain size of 320 nm after one cycle of repetitive tube expansion and shrinking. The yield strength, ultimate tensile strength increased notably by the factor of 2.17 and 1.27 respectively, after one cycle of repetitive tube expansion and shrinking, whereas the elongation to failure as well as the uniform elongation decreased. Furthermore, micro-hardness distribution through the part's section proposed the hardness increasing to ~ 55 HV from the initial value of ~ 28 HV after one cycle of repetitive tube expansion and shrinking. - Highlights: • RTES was introduced for fabricating the UFGed AA1050 tubes for the first time. • Nano-grained AA1050 tube was obtained by RTES process. • Grain size of ~ 320 nm was obtained after two half-cycles of RTES process. • Yield and ultimate strength increased by the factor of 2.17 and 1.27 respectively. • The microhardness increased to ~ 55 HV from the initial value of ~ 28 HV.

  10. Ultrafine particles cross cellular membranes by nonphagocytic mechanisms in lungs and in cultured cells.

    PubMed

    Geiser, Marianne; Rothen-Rutishauser, Barbara; Kapp, Nadine; Schürch, Samuel; Kreyling, Wolfgang; Schulz, Holger; Semmler, Manuela; Im Hof, Vinzenz; Heyder, Joachim; Gehr, Peter

    2005-11-01

    High concentrations of airborne particles have been associated with increased pulmonary and cardiovascular mortality, with indications of a specific toxicologic role for ultrafine particles (UFPs; particles < 0.1 microm). Within hours after the respiratory system is exposed to UFPs, the UFPs may appear in many compartments of the body, including the liver, heart, and nervous system. To date, the mechanisms by which UFPs penetrate boundary membranes and the distribution of UFPs within tissue compartments of their primary and secondary target organs are largely unknown. We combined different experimental approaches to study the distribution of UFPs in lungs and their uptake by cells. In the in vivo experiments, rats inhaled an ultrafine titanium dioxide aerosol of 22 nm count median diameter. The intrapulmonary distribution of particles was analyzed 1 hr or 24 hr after the end of exposure, using energy-filtering transmission electron microscopy for elemental microanalysis of individual particles. In an in vitro study, we exposed pulmonary macrophages and red blood cells to fluorescent polystyrene microspheres (1, 0.2, and 0.078 microm) and assessed particle uptake by confocal laser scanning microscopy. Inhaled ultrafine titanium dioxide particles were found on the luminal side of airways and alveoli, in all major lung tissue compartments and cells, and within capillaries. Particle uptake in vitro into cells did not occur by any of the expected endocytic processes, but rather by diffusion or adhesive interactions. Particles within cells are not membrane bound and hence have direct access to intracellular proteins, organelles, and DNA, which may greatly enhance their toxic potential. PMID:16263511

  11. Iron Fischer-Tropsch catalysis: Properties of an ultrafine iron oxide catalyst. Quarterly progress report, July--September 1992

    SciTech Connect

    Xu, Liguang; Bao, Shiqi; O`Brien, R.; Houpt, D.; Davis, B.H.

    1992-12-31

    A commercial Fe oxide with a particle size of 3 nm is now available. The FT requires considerable time on stream before steady state conditions are attained. Since it is desirable to obtain FT data for the smaller ultrafine Fe oxide catalysts at larger times on steam, data for operation up to 6 months were collected using slurry phase. Results show that the ultrafine Fe oxide maintain catalytic activity for a 150-day operating period. Addition of 0.5% K increased the activity; after 56 days, the activity had declined to and below that of unpromoted catalyst. Neither the unpromoted nor K-promoted catalyst exhibited good selectivity for alkenes.

  12. Enhanced protective properties of epoxy/polyaniline-camphorsulfonate nanocomposite coating on an ultrafine-grained metallic surface

    NASA Astrophysics Data System (ADS)

    Pour-Ali, Sadegh; Kiani-Rashid, Alireza; Babakhani, Abolfazl; Davoodi, Ali

    2016-07-01

    An ultrafine-grained surface layer on mild steel substrate with average grain size of 77 nm was produced through wire brushing process. Surface grain size was determined through transmission electron microscopy and X-ray diffraction methods. This substrate was coated with epoxy and an in situ synthesized epoxy/polyaniline-camphorsulfonate (epoxy/PANI-CSA) nanocomposite. The corrosion behavior was studied by open circuit potential, potentiodynamic polarization and impedance measurements. Results of electrochemical tests evidenced the enhanced protective properties of epoxy/PANI-CSA coating on the substrate with ultrafine-grained surface.

  13. Deformation behavior and fracture of the ultrafine-grained titanium alloy of Ti-Al-V-Mo system

    NASA Astrophysics Data System (ADS)

    Grabovetskaya, Galina; Mishin, Ivan; Zabudchenko, Olga

    2015-10-01

    Effect of prerecrystallization annealing on the evolution of structural and phase state, deformation and failure behavior of the ultrafine-grained structure of VT16 grade titanium alloy is studied. In the ultrafine-grained VT16 alloy during prerecrystallization annealing such processes as the β→α phase transformation and redistribution of alloying elements is found to take place along with defect structure relieving, leading to strength properties decrease. These processes promote retention of high level of alloy strength properties. Failure behavior of the alloy qualitatively is in agreement with the wave theory of fracture.

  14. Observations of ultra-fine particles above a deciduous forest in Denmark

    NASA Astrophysics Data System (ADS)

    Pryor, S. C.; Barthelmie, R. J.; Prip, H.; Sørensen, L. L.

    2005-03-01

    We report physical particle size distribution and chemical composition data over a Beech forest in Denmark during May and June of 2004 with a focus on four days characterized by high concentrations of ultra-fine particles. Highest number concentrations of sub-30 nm particles were observed when net radiation >300 W m-2 and ambient particle surface area <100 μm2 cm-3. The 10-30 nm particles show growth rates of 1.5-4.5 nm hr-1 and are comprised predominantly of ammonium, sulfate and associated water.

  15. Ultrafine particle size distribution during high velocity impact of high density metals

    NASA Astrophysics Data System (ADS)

    Buonanno, Giorgio; Stabile, Luca; Ruggiero, Andrew; Iannitti, Gianluca; Bonora, Nicola

    2012-03-01

    In the event of high-energy penetrator impact, people involved in battlefield scenarios are exposed to the additional hazard stemming from ultrafine metallic particles, i.e. exposure, inhalation, and respiration of aerolized metals. In order to have reliable quantitative measurement of the aerosol particles generated under controlled impact conditions, an experimental set-up was designed to perform impact tests with light gas-gun in chamber. During the impact events, aerosol particle size distributions and total concentrations were measured with a one-second time resolution. In this study preliminary results relative to high purity copper projectile impact at different velocities are presented.

  16. High-strength ultrafine-grained tungsten-carbide-based materials obtained by spark plasma sintering

    NASA Astrophysics Data System (ADS)

    Chuvil'deev, V. N.; Blagoveshchenskii, Yu. V.; Boldin, M. S.; Sakharov, N. V.; Nokhrin, A. V.; Isaeva, N. V.; Shotin, S. V.; Lopatin, Yu. G.; Belkin, O. A.; Smirnova, E. S.

    2015-04-01

    Ultrafine-grained (UFG) tungsten carbide (WC) samples with high hardness (up to 34 GPa) and increased cracking resistance have been obtained by the method of spark plasma sintering (SPS). Initial powders have been prepared by two-stage plasmachemical synthesis. The influence of the initial size of WC nanoparticles on the density, structural parameters, and mechanical properties of UFG tungsten carbide obtained by SPS has been studied. It is established that the phenomenon of accelerated sintering of WC powder is related to enhanced grain-boundary diffusion.

  17. Method for the removal of ultrafine particulates from an aqueous suspension

    DOEpatents

    Chaiko, David J.; Kopasz, John P.; Ellison, Adam J. G.

    2000-01-01

    A method of separating ultra-fine particulates from an aqueous suspension such as a process stream or a waste stream. The method involves the addition of alkali silicate and an organic gelling agent to a volume of liquid, from the respective process or waste stream, to form a gel. The gel then undergoes syneresis to remove water and soluble salts from the gel containing the particulates, thus, forming a silica monolith. The silica monolith is then sintered to form a hard, nonporous waste form.

  18. Microstructure and mechanical behavior of neutron irradiated ultrafine grained ferritic steel

    SciTech Connect

    Ahmad Alsabbagh; Apu Sarkar; Brandon Miller; Jatuporn Burns; Leah Squires; Douglas Porter; James I. Cole; K. L. Murty

    2014-10-01

    Neutron irradiation effects on ultra-fine grain (UFG) low carbon steel prepared by equal channel angular pressing (ECAP) has been examined. Counterpart samples with conventional grain (CG) sizes have been irradiated alongside with the UFG ones for comparison. Samples were irradiated in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL) to 1.24 dpa. Atom probe tomography revealed manganese, silicon-enriched clusters in both ECAP and CG steel after neutron irradiation. X-ray quantitative analysis showed that dislocation density in CG increased after irradiation. However, no significant change was observed in UFG steel revealing better radiation tolerance.

  19. Synthesis of zinc ultrafine powders via the Guen-Miller flow-levitation method

    NASA Astrophysics Data System (ADS)

    Jigatch, A. N.; Leipunskii, I. O.; Kuskov, M. L.; Afanasenkova, E. S.; Berezkina, N. G.; Gorbatov, S. A.

    2015-12-01

    Zinc ultrafine powders (UFPs) with the average particle size of 0.175 to 1.24 μm are synthesized via the flow-levitation method. The peculiarities of the formation of zinc UFPs are considered with respect to the carrier gas properties (heat capacity, thermal conductivity, and diffusion coefficient), as well as the gas flow parameters (pressure and flow rate). The obtained zinc particles are studied via scanning electron microscopy and X-ray diffraction. The factors determining the crystal structure of zinc particles and their size distribution are discussed as well. The data on oxidation of zinc stored in unsealed containers under normal conditions are also presented.

  20. Initial study of dry ultrafine coal beneficiation utilizing triboelectric charging with subsequent electrostatic separation

    SciTech Connect

    Link, T.A.; Killmeyer, R.P.; Elstrodt, R.H.; Haden, N.H.

    1990-10-01

    A novel, dry process using electrostatics to beneficiate ultrafine coal is being developed by the Coal Preparation Division at the Pittsburgh Energy Technology Center. The historical concept of triboelectricity and its eventual use as a means of charging coal for electrostatic separation will be discussed. Test data from a first-generation and a second-generation Tribo-Electrostatic separator are presented showing the effects of feed particle size, separator voltage, solids concentration in air, and particle velocity on separation performance. 10 refs., 10 figs., 9 tabs.

  1. Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

    PubMed

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

    With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications. PMID:27116255

  2. Synthesis of zinc ultrafine powders via the Guen–Miller flow-levitation method

    SciTech Connect

    Jigatch, A. N. Leipunskii, I. O.; Kuskov, M. L.; Afanasenkova, E. S.; Berezkina, N. G.; Gorbatov, S. A.

    2015-12-15

    Zinc ultrafine powders (UFPs) with the average particle size of 0.175 to 1.24 μm are synthesized via the flow-levitation method. The peculiarities of the formation of zinc UFPs are considered with respect to the carrier gas properties (heat capacity, thermal conductivity, and diffusion coefficient), as well as the gas flow parameters (pressure and flow rate). The obtained zinc particles are studied via scanning electron microscopy and X-ray diffraction. The factors determining the crystal structure of zinc particles and their size distribution are discussed as well. The data on oxidation of zinc stored in unsealed containers under normal conditions are also presented.

  3. Pseudophasic extraction method for the separation of ultra-fine minerals

    DOEpatents

    Chaiko, David J.

    2002-01-01

    An improved aqueous-based extraction method for the separation and recovery of ultra-fine mineral particles. The process operates within the pseudophase region of the conventional aqueous biphasic extraction system where a low-molecular-weight, water soluble polymer alone is used in combination with a salt and operates within the pseudo-biphase regime of the conventional aqueous biphasic extraction system. A combination of low molecular weight, mutually immiscible polymers are used with or without a salt. This method is especially suited for the purification of clays that are useful as rheological control agents and for the preparation of nanocomposites.

  4. Investigation of compaction and sintering behavior of SiC powder after ultra-fine treatment.

    PubMed

    Guo, Xing-Zhong; Yang, Hui

    2004-08-01

    Silicon carbide ceramics were prepared with SiC powder treated by the fluidized bed opposed jet mill as raw materials, and the effects of the ultra-fine treatment mechanism on the compaction and sintering behavior of SiC ceramics were investigated. The results showed that the compacts had higher density and microstructure homogeneity when the sintering temperature of the compact was decreased; and that the surface microstructure, densification and mechanical properties of the sintered body could be ameliorated obviously. PMID:15236481

  5. Electrochemical and cellular behavior of ultrafine-grained titanium in vitro.

    PubMed

    Maleki-Ghaleh, H; Hajizadeh, K; Hadjizadeh, A; Shakeri, M S; Ghobadi Alamdari, S; Masoudfar, S; Aghaie, E; Javidi, M; Zdunek, J; Kurzydlowski, K J

    2014-06-01

    The electrochemical and cellular behavior of commercially pure titanium (CP-Ti) with both ultrafine-grained (UFG) and coarse-grained (CG) microstructure was evaluated in this study. Equal channel angular pressing was used to produce the UFG structure titanium. Polarization and electrochemical impedance tests were carried out in a simulated body fluid (SBF) at 37°C. Cellular behaviors of samples were assessed using fibroblast cells. Results of the investigations illustrate the improvement of both corrosion and biological behavior of UFG CP-Ti in comparison with the CG counterpart. PMID:24863228

  6. Ultrafine-grained structure formation in Ti-6Al-4V alloy via warm swaging

    NASA Astrophysics Data System (ADS)

    Klimova, M.; Boeva, M.; Zherebtsov, S.; Salishchev, G.

    2014-08-01

    The influence of warm swaging on the structure and properties of Ti-6Al-4V alloy was studied. Warm swaging of the alloy in the interval 680-500°C with the total strain of ɛ=2.66 was found to be resulted in the formation of a homogeneous globular microstructure with a grain size of 0.4 μm in both longitudinal and transversal sections. Room temperature tensile strength and tensile elongation of the swaged alloy was 1315MPa and 10.5%, respectively. Ultrafine-grained Ti-6Al-4V alloy produced by swaging exhibited good workability at 600-700 °C.

  7. Orientation influence on grain size-effects in ultrafine-grained magnesium

    DOE PAGESBeta

    Fan, Haidong; Aubry, Sylvie; Arsenlis, A.; El-Awady, Jaafar

    2014-11-08

    The mechanical behavior of ultrafine-grained magnesium was studied by discrete dislocation dynamics (DDD) simulations. Our results show basal slip yields a strong size effect, while prismatic and pyramidal slips produce a weak one. We developed a new size-strength model that considers dislocation transmission across grain boundaries. Good agreement between this model, current DDD simulations and previous experiments is observed. These results reveal that the grain size effect depends on 3 factors: Peierls stress, dislocation source strength and grain boundary strength.

  8. Synthesis And Characterization Of Ultra-fine Zinc Substituted Lithium Ferrites

    NASA Astrophysics Data System (ADS)

    Soibam, Ibetombi; Phanjoubam, Sumitra; Sarma, HNK; Prakash, Chandra

    2008-04-01

    Ultrafine substituted lithium ferrite having the compositional formula Li0.5-0.5xZnxFe2.5-0.5xO4 where 0⩽x⩽1.0 in steps of 0.2 were prepared by the citrate Precursor method. A nitrate citrate gel was prepared from metal nitrates and citric acid, which exhibits self-propagating combustion behaviour. Spinel structure of the synthesized ferrite was confirmed by XRD analysis. The variation in lattice parameter and density with zinc concentration is studied.

  9. Flax Fiber - Interfacial Bonding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Measured flax fiber physical and chemical properties potentially impact bonding and thus stress transfer between the matrix and fiber within composites. These first attempts at correlating flax fiber quality and biofiber composites contain the initial steps towards identifying key flax fiber charac...

  10. High-fiber foods

    MedlinePlus

    Dietary fiber - self-care ... Dietary fiber adds bulk to your diet. Because it makes you feel full faster, it can help you ... Grains are another important source of dietary fiber. Eat more: ... Whole-grain breads Brown rice Popcorn High-fiber cereals, such ...

  11. Tea Dietary Fiber Improves Serum and Hepatic Lipid Profiles in Mice Fed a High Cholesterol Diet.

    PubMed

    Guo, Wenxin; Shu, Yang; Yang, Xiaoping

    2016-06-01

    Tea dietary fiber (TDF) was prepared from tea residues and modified to get cellulose-modified TDF (CTDF) by cellulase or micronized TDF (MTDF) by ultrafine grinding. The in vitro lipid-binding capacities of the three fibers and their effects on serum and hepatic lipid profiles in mice fed a high cholesterol diet were evaluated. The results showed that the three fibers had excellent lipid-binding capacities, and the cholesterol- and sodium cholate-binding capacities of CTDF and MTDF were significantly higher than those of TDF. Animal studies showed that, compared to model control, the three fibers significantly decreased mice average daily gain, gain: feed, and liver index, reduced total cholesterol (TC), triglyceride, and low density lipoprotein-cholesterol of serum and liver, increased serum and hepatic high density lipoprotein-cholesterol to TC ratio, and promoted the excretion of fecal lipids, and they also significantly increased the activities of superoxide dismutase and glutathione peroxidase of serum and liver, and decreased lipid peroxidation; moreover, the effects of CTDF and MTDF were better than that of TDF. It was concluded that the three fibers could improve serum and hepatic lipid profiles in mice fed a high cholesterol diet and the mechanism of action might be due to the promotion of fecal excretion of lipids through their lipid-binding ability and the inhibition of lipid peroxidation. These findings suggest that tea dietary fiber has the potential to be used as a functional ingredient to control cardiovascular disease. PMID:27040277

  12. Fiber optic connector

    DOEpatents

    Rajic, S.; Muhs, J.D.

    1996-10-22

    A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded are disclosed. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled. 3 figs.

  13. Fiber optic connector

    DOEpatents

    Rajic, Slobodan; Muhs, Jeffrey D.

    1996-01-01

    A fiber optic connector and method for connecting composite materials within which optical fibers are imbedded. The fiber optic connector includes a capillary tube for receiving optical fibers at opposing ends. The method involves inserting a first optical fiber into the capillary tube and imbedding the unit in the end of a softened composite material. The capillary tube is injected with a coupling medium which subsequently solidifies. The composite material is machined to a desired configuration. An external optical fiber is then inserted into the capillary tube after fluidizing the coupling medium, whereby the optical fibers are coupled.

  14. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor); Mattes, Brenton L. (Inventor); Charnetski, Clark J. (Inventor)

    1999-01-01

    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

  15. Fiber optic temperature sensor

    NASA Technical Reports Server (NTRS)

    Sawatari, Takeo (Inventor); Gaubis, Philip A. (Inventor)

    2000-01-01

    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface.

  16. Coatings for graphite fibers

    NASA Technical Reports Server (NTRS)

    Galasso, F. S.; Scola, D. A.; Veltri, R. D.

    1980-01-01

    Graphite fibers released from composites during burning or an explosion caused shorting of electrical and electronic equipment. Silicon carbide, silica, silicon nitride and boron nitride were coated on graphite fibers to increase their electrical resistances. Resistances as high as three orders of magnitude higher than uncoated fiber were attained without any significant degradation of the substrate fiber. An organo-silicone approach to produce coated fibers with high electrical resistance was also used. Celion 6000 graphite fibers were coated with an organo-silicone compound, followed by hydrolysis and pyrolysis of the coating to a silica-like material. The shear and flexural strengths of composites made from high electrically resistant fibers were considerably lower than the shear and flexural strengths of composites made from the lower electrically resistant fibers. The lower shear strengths of the composites indicated that the coatings on these fibers were weaker than the coating on the fibers which were pyrolyzed at higher temperature.

  17. Fiber optic monitoring device

    DOEpatents

    Samborsky, James K.

    1993-01-01

    A device for the purpose of monitoring light transmissions in optical fibers comprises a fiber optic tap that optically diverts a fraction of a transmitted optical signal without disrupting the integrity of the signal. The diverted signal is carried, preferably by the fiber optic tap, to a lens or lens system that disperses the light over a solid angle that facilitates viewing. The dispersed light indicates whether or not the monitored optical fiber or system of optical fibers is currently transmitting optical information.

  18. Alumina fiber strength improvement

    NASA Technical Reports Server (NTRS)

    Pepper, R. T.; Nelson, D. C.

    1982-01-01

    The effective fiber strength of alumina fibers in an aluminum composite was increased to 173,000 psi. A high temperature heat treatment, combined with a glassy carbon surface coating, was used to prevent degradation and improve fiber tensile strength. Attempts to achieve chemical strengthening of the alumina fiber by chromium oxide and boron oxide coatings proved unsuccessful. A major problem encountered on the program was the low and inconsistent strength of the Dupont Fiber FP used for the investigation.

  19. Separation of Fischer-Tropsch Wax Products from Ultrafine Iron Catalyst Particles

    SciTech Connect

    James K. Neathery; Gary Jacobs; Amitava Sarkar; Adam Crawford; Burtron H. Davis

    2006-09-30

    In the previous reporting period, modifications were completed for integrating a continuous wax filtration system for a 4 liter slurry bubble column reactor. During the current reporting period, a shakedown of the system was completed. Several problems were encountered with the progressive cavity pump used to circulate the wax/catalyst slurry though the cross-flow filter element and reactor. During the activation of the catalyst with elevated temperature (> 270 C) the elastomer pump stator released sulfur thereby totally deactivating the iron-based catalyst. Difficulties in maintaining an acceptable leak rate from the pump seal and stator housing were also encountered. Consequently, the system leak rate exceeded the expected production rate of wax; therefore, no online filtration could be accomplished. Work continued regarding the characterization of ultra-fine catalyst structures. The effect of carbidation on the morphology of iron hydroxide oxide particles was the focus of the study during this reporting period. Oxidation of Fe (II) sulfate results in predominantly {gamma}-FeOOH particles which have a rod-shaped (nano-needles) crystalline structure. Carbidation of the prepared {gamma}-FeOOH with CO at atmospheric pressure produced iron carbides with spherical layered structure. HRTEM and EDS analysis revealed that carbidation of {gamma}-FeOOH particles changes the initial nano-needles morphology and generates ultrafine carbide particles with irregular spherical shape.

  20. Experimental investigation of submicron and ultrafine soot particle removal by tree leaves

    NASA Astrophysics Data System (ADS)

    Hwang, Hee-Jae; Yook, Se-Jin; Ahn, Kang-Ho

    2011-12-01

    Soot particles emitted from vehicles are one of the major sources of air pollution in urban areas. In this study, five kinds of trees were selected as Pinus densiflora, Taxus cuspidata, Platanus occidentalis, Zelkova serrata, and Ginkgo biloba, and the removal of submicron (<1 μm) and ultrafine (<0.1 μm) soot particles by tree leaves was quantitatively compared in terms of deposition velocity. Soot particles were produced by a diffusion flame burner using acetylene as the fuel. The sizes of monodisperse soot particles classified with the Differential Mobility Analyzers (DMA) were 30, 55, 90, 150, 250, 400, and 600 nm. A deposition chamber was designed to simulate the omni-directional flow condition around the tree leaves. Deposition velocities onto the needle-leaf trees were higher than those onto the broadleaf trees. P. densiflora showed the greatest deposition velocity, followed by T. cuspidata, Platanus occidentalis, Zelkova serrata, and Ginkgo biloba. In addition, from the comparison of deposition velocity between two groups of Platanus occidentalis leaves, i.e. one group of leaves with front sides only and the other with back sides only, it was supposed in case of the broadleaf trees that the removal of airborne soot particles of submicron and ultrafine sizes could be affected by the surface roughness of tree leaves, i.e. the veins and other structures on the leaves.

  1. Deposition of inhaled charged ultrafine particles in a simple tracheal model

    SciTech Connect

    Cohen, B.S.; Ayres, L.; Xiong, J.

    1992-01-01

    The deposition of ultrafine (d [le] 200 nm) particles on airway surfaces is an important determinant of the radiation dose that results from inhalation of radon progeny. The activity median diameter of particles to which radon daughters attach is small (10--140 nm). In the absence of charge, deposition in the upper airways of the respiratory system occurs by impaction for large particles and diffusion for small particles. Sedimentation is negligible due to the high flow rates in these airways. Experiments conducted in hollow casts and in vivo in humans have all shown an increase in deposition due to the particle charge. In vivo experimental results showed that there exists a threshold value of charge on the particle (q[sub c]) above which the electrostatic charge enhances deposition. These experiments were performed for particles for which deposition by diffusion is small (d [le] 300 nm). Deposition of ultrafine particles in the airways may occur by a combined mechanism of diffusion and electrostatic charge.

  2. Deposition of inhaled charged ultrafine particles in a simple tracheal model

    SciTech Connect

    Cohen, B.S.; Ayres, L.; Xiong, J.

    1992-11-01

    The deposition of ultrafine (d {le} 200 nm) particles on airway surfaces is an important determinant of the radiation dose that results from inhalation of radon progeny. The activity median diameter of particles to which radon daughters attach is small (10--140 nm). In the absence of charge, deposition in the upper airways of the respiratory system occurs by impaction for large particles and diffusion for small particles. Sedimentation is negligible due to the high flow rates in these airways. Experiments conducted in hollow casts and in vivo in humans have all shown an increase in deposition due to the particle charge. In vivo experimental results showed that there exists a threshold value of charge on the particle (q{sub c}) above which the electrostatic charge enhances deposition. These experiments were performed for particles for which deposition by diffusion is small (d {le} 300 nm). Deposition of ultrafine particles in the airways may occur by a combined mechanism of diffusion and electrostatic charge.

  3. Ultrafine particle removal and ozone generation by in-duct electrostatic precipitators.

    PubMed

    Poppendieck, Dustin G; Rim, Donghyun; Persily, Andrew K

    2014-01-01

    Human exposure to airborne ultrafine particles (UFP, < 100 nm) has been shown to have adverse health effects and can be elevated in buildings. In-duct electrostatic precipitator filters (ESP) have been shown to be an effective particulate control device for reducing UFP concentrations (20-100 nm) in buildings, although they have the potential to increase indoor ozone concentrations. This study investigated residential ESP filters to reduce ultrafine particles between 4 to 15 nm and quantified the resulting ozone generation. In-duct ESPs were operated in the central air handling unit of a test house. Results for the two tested ESP brands indicate that removal efficiency of 8 to 14 nm particles was near zero and always less than 10% (± 15%), possibly due to particle generation or low charging efficiency. Adding a media filter downstream of the ESP increased the decay rate for particles in the same size range. Continuous operation of one brand of ESP raised indoor ozone concentrations to 77 ppbv and 20 ppbv for a second brand. Using commercial filters containing activated carbon downstream of the installed ESP reduced the indoor steady-state ozone concentrations between 6% and 39%. PMID:24387032

  4. Surface damage in ultrafine and multimodal grained tungsten materials induced by low energy helium irradiation

    NASA Astrophysics Data System (ADS)

    El-Atwani, Osman; Efe, Mert; Heim, Bryan; Allain, Jean Paul

    2013-03-01

    Although tungsten is considered the best candidate as a plasma facing component (PFC) in the divertor region in the International Thermonuclear Experimental Reactor (ITER), severe morphology changes such as cavities, blisters, bubbles and nanostructure formation are expected. Increasing defect sinks in the tungsten microstructure is one of the possible solutions to mitigate the irradiation damage. In this work, helium irradiation at low energy (50 and 200 eV) and temperatures of 600 (threshold of vacancy migration) and 950 °C were performed on multimodal and ultrafine grained tungsten prepared by spark plasma sintering and severe plastic deformation (SPD), respectively. The multimodal samples consisted of small grains (300-700 nm size) juxtaposed to larger grains (1-3 μm size). Detachment of the small grains was observed in the multimodal grained tungsten irradiated at 600 °C and a fluence of 1 × 1022 m-2 due to grain boundary grooving. On the same sample but at 950 °C, detachment and nanostructuring of the small grains were observed together with recrystallization of the large grains. Irradiation of the SPD samples at 200 eV and 950 °C to a fluence of about 2 × 1022 m-2, resulted in nanostructuring of the ultrafine grained shear bands in the microstructure.

  5. Ultrafine particle removal by residential heating, ventilating, and air-conditioning filters.

    PubMed

    Stephens, B; Siegel, J A

    2013-12-01

    This work uses an in situ filter test method to measure the size-resolved removal efficiency of indoor-generated ultrafine particles (approximately 7-100 nm) for six new commercially available filters installed in a recirculating heating, ventilating, and air-conditioning (HVAC) system in an unoccupied test house. The fibrous HVAC filters were previously rated by the manufacturers according to ASHRAE Standard 52.2 and ranged from shallow (2.5 cm) fiberglass panel filters (MERV 4) to deep-bed (12.7 cm) electrostatically charged synthetic media filters (MERV 16). Measured removal efficiency ranged from 0 to 10% for most ultrafine particles (UFP) sizes with the lowest rated filters (MERV 4 and 6) to 60-80% for most UFP sizes with the highest rated filter (MERV 16). The deeper bed filters generally achieved higher removal efficiencies than the panel filters, while maintaining a low pressure drop and higher airflow rate in the operating HVAC system. Assuming constant efficiency, a modeling effort using these measured values for new filters and other inputs from real buildings shows that MERV 13-16 filters could reduce the indoor proportion of outdoor UFPs (in the absence of indoor sources) by as much as a factor of 2-3 in a typical single-family residence relative to the lowest efficiency filters, depending in part on particle size. PMID:23590456

  6. Aviation Emissions Impact Ambient Ultrafine Particle Concentrations in the Greater Boston Area.

    PubMed

    Hudda, N; Simon, M C; Zamore, W; Brugge, D; Durant, J L

    2016-08-16

    Ultrafine particles are emitted at high rates by jet aircraft. To determine the possible impacts of aviation activities on ambient ultrafine particle number concentrations (PNCs), we analyzed PNCs measured from 3 months to 3.67 years at three sites within 7.3 km of Logan International Airport (Boston, MA). At sites 4.0 and 7.3 km from the airport, average PNCs were 2- and 1.33-fold higher, respectively, when winds were from the direction of the airport compared to other directions, indicating that aviation impacts on PNC extend many kilometers downwind of Logan airport. Furthermore, PNCs were positively correlated with flight activity after taking meteorology, time of day and week, and traffic volume into account. Also, when winds were from the direction of the airport, PNCs increased with increasing wind speed, suggesting that buoyant aircraft exhaust plumes were the likely source. Concentrations of other pollutants [CO, black carbon (BC), NO, NO2, NOx, SO2, and fine particulate matter (PM2.5)] decreased with increasing wind speed when winds were from the direction of the airport, indicating a different dominant source (likely roadway traffic emissions). Except for oxides of nitrogen, other pollutants were not correlated with flight activity. Our findings point to the need for PNC exposure assessment studies to take aircraft emissions into consideration, particularly in populated areas near airports. PMID:27490267

  7. Consecutively Preparing D-Xylose, Organosolv Lignin, and Amorphous Ultrafine Silica from Rice Husk

    PubMed Central

    Zhang, Hongxi; Ding, Xuefeng; Wang, Zichen; Zhao, Xu

    2014-01-01

    Rice husk is an abundant agricultural by-product reaching the output of 80 million tons annually in the world. The most common treatment method of rice husk is burning or burying, which caused serious air pollution and resource waste. In order to solve this problem, a new method is proposed to comprehensively utilize the rice husk in this paper. Firstly, the D-xylose was prepared from the semicellulose via dilute acid hydrolysis. Secondly, the lignin was separated via organic solvent pulping from the residue. Finally, the amorphous ultrafine silica was prepared via pyrolysis of the residue produced in the second process. In this way, the three main contents of rice husk (semicellulose, lignin, and silica) are consecutively converted to three fine chemicals, without solid waste produced. The yields of D-xylose and organosolv lignin reach 58.2% and 58.5%, respectively. The purity and specific surface of amorphous ultrafine silica reach 99.92% and 225.20 m2/g. PMID:25140120

  8. Negligible clearance of ultrafine particles retained in healthy and affected human lungs.

    PubMed

    Wiebert, P; Sanchez-Crespo, A; Seitz, J; Falk, R; Philipson, K; Kreyling, W G; Möller, W; Sommerer, K; Larsson, S; Svartengren, M

    2006-08-01

    Ambient particles are believed to be a specific health hazard, although the underlying mechanisms are not fully understood. There are data in the literature indicating fast and substantial systemic uptake of particles from the lung. The present authors have developed an improved method to produce ultrafine particles with more stable radiolabelling and defined particle size range. Fifteen subjects inhaled technetium 99m (99mTc)-labelled carbonaceous particles of 100 nm in size. Radioactivity over the lung was followed for 70 h. The clearance of these ultrafine particles from the lungs and specifically translocation to the circulation was tested. Lung retention for all subjects at 46 h was mean+/-sd 99+/-4.6%. Cumulative leaching of 99mTc activity from the particles was 2.6+/-0.96% at 70 h. The 24-h activity leaching in urine was 1.0+/-0.55%. No evidence of a quantitatively important translocation of 100-nm particles to the systemic circulation from the lungs was found. More research is needed to establish if the approximately 1% cleared activity originates from leached activity or insoluble translocated particles, and whether a few per cent of translocated particles is sufficient to cause harmful effects. PMID:16641121

  9. Biogenic iodine emissions and identification of end-products in coastal ultrafine particles during nucleation bursts

    NASA Astrophysics Data System (ADS)

    MäKelä, J. M.; Hoffmann, T.; Holzke, C.; VäKevä, M.; Suni, T.; Mattila, T.; Aalto, P. P.; Tapper, U.; Kauppinen, E. I.; O'Dowd, C. D.

    2002-10-01

    Ultrafine particles sampled during new particle formation bursts observed in the coastal zone were studied with transmission electron microscopy (TEM) and elemental analysis using energy-dispersive X ray (EDX). It was observed that both iodine and sulphur were present in the new particles with diameter below 10 mn. Gaseous emissions of halogen compounds from seaweeds were also measured at the same location during low-tide particle nucleation episodes. Based on the presence of iodine in the particle phase during low-tide nucleation bursts, and the significant emission of iodine compounds from the seaweeds during these periods, it is apparent that part of the biogenic iodine species emitted from the seaweeds end up in the ultrafine particulate phase. It was not possible to quantitatively determine the iodine content in the particles; however, in most cases the relative contribution from iodine and sulphate was similar, while some cases indicated no sulphate. On larger sized particles the contribution of sulphate was significantly higher than iodine. It appears that the condensable species leading to the appearance of new particles in the coastal atmosphere is an iodine species. Whether or not this iodine species also participates in the nucleation of new stable clusters could not be completely verified.

  10. Radiation grafting of maleic anhydride onto polypropylene in solid state via ultrafine blend

    NASA Astrophysics Data System (ADS)

    Tan, Xiumin

    2014-05-01

    A novel method to prepare maleic anhydride grafting onto poly (propylene) (PP-g-MAH) was described. It was performed by γ-irradiation in solid state via ultrafine blend in the absence of any initiator and the grafting mechanism was proposed based on the experimental results. First, ultrafine blend of MAH and PP was prepared through ultrasonic initiation in melt state and then cooled rapidly. Second, the blend was radiated by γ-irradiation in the circumstance of atmosphere. Effects of irradiation dose and MAH concentration on the amount of grafted MAH were investigated. Compared with the conventional solid-state radiation grafting method, PP-g-MAH obtained via this method shows a higher graft rate of MAH. This novel method also has the advantages of solventless, energy efficient, low cost and simple operation. Furthermore, it is very easy to get purified products. The molecular structures of grafted copolymer were characterized by Fourier-transform infrared spectroscopy. Differential scanning calorimetry, wide-angle X-ray diffraction and polarized optical microscope were used to determine the degree of crystallinity and crystalline structure.

  11. Ultrafine coal single stage dewatering and briquetting process. Technical report, December 1, 1994--February 28, 1995

    SciTech Connect

    Wilson, J.W.

    1996-03-01

    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 that are produced are difficult to dewater and they create problems in coal transportation as well as in its storage and handling at utility plants. The objective of this research project is to combine 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, two types of coal samples have been tested for use in the dewatering and briquetting processes. These tests were carried out using Orimulsion as the dewatering reagent. A ram extruder that can be operated continuously is used to fabricate dewatered pellets. The influence of compaction pressure, curing time, binder concentration (2% to 5%), particle size, and compacting time on the performance of coal pellets have been evaluated in terms of their water resistance and wear vulnerability.

  12. Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions

    SciTech Connect

    El-atwani, O.; Hattar, Khalid Mikhiel; Hinks, J. A.; Greaves, G.; Harilal, S. S.; Hassanein, A.

    2014-12-25

    We investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. Moreover, at energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. Finally, we discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formation.

  13. Characteristics of nano-/ultrafine particle-bound PAHs in ambient air at an international airport.

    PubMed

    Lai, Chia-Hsiang; Chuang, Kuen-Yuan; Chang, Jin-Wei

    2013-03-01

    Concentrations of 22 polycyclic aromatic hydrocarbons (PAHs) were estimated for individual particle-size distributions at the airport apron of the Taipei International Airport, Taiwan, on 48 days in July, September, October, and December of 2011. In total, 672 integrated air samples were collected using a micro-orifice uniform deposition impactor (MOUDI) and a nano-MOUDI. Particle-bound PAHs (P-PAHs) were analyzed by gas chromatography with mass selective detector (GC/MSD). The five most abundant species of P-PAHs on all sampling days were naphthalene (NaP), phenanthrene (PA), fluoranthene (FL), acenaphthene (AcP), and pyrene (Pyr). Total P-PAHs concentrations were 152.21, 184.83, and 188.94 ng/m(3) in summer, autumn, and winter, respectively. On average, the most abundant fractions of benzo[a]pyrene equivalent concentration (BaPeq) in different molecular weights were high-weight PAHs (79.29 %), followed by medium-weight PAHs (11.57 %) and low-weight PAHs (9.14 %). The mean BaPeq concentrations were 1.25 and 0.94 (ng/m(3)) in ultrafine particles (<0.1 μm) and nano-particles (<0.032 μm), respectively. The percentages of total BaPeq in nano- and ultrafine particulate size ranges were 52.4 % and 70.15 %, respectively. PMID:22821344

  14. Ultrafine Na-4-mica: uptake of alkali and alkaline earth metal cations by ion exchange.

    PubMed

    Kodama, Tatsuya; Ueda, Masahito; Nakamuro, Yumiko; Shimizu, Ken-ichi; Komarneni, Sridhar

    2004-06-01

    The cation exchange properties of alkali and alkaline earth metal cations at room temperature were investigated on an ultrafine, highly charged Na-4-mica (with the ideal mica composition Na4Mg6Al4Si4O20F4.xH2O). Ultrafine mica crystallites of 200 nm in size led to faster Sr2+ uptake kinetics in comparison to larger mica crystallites. The alkali metal ion (K+, Cs+, and Li+) exchange uptake was rapid, and complete exchange occurred within 30 min. For the alkaline earth metal ions Ba2+, Ca2+, and Mg2+, however, the exchange uptake required lengthy periods from 3 days to 4 weeks to be completed, similar to its Sr uptake, as previously reported. Kinetic models of the modified Freundlich and parabolic diffusion were examined for the experimental data on the Ba2+, Ca2+, and Mg2+ uptakes. The modified Freundlich model described well the Ba2+ ion uptake kinetics as well as that for the Sr2+ ion, while for the Ca2+ and Mg2+ ions the parabolic diffusion model showed better fitting. The alkali and alkaline earth ion exchange isotherms were also determined in comparison to the Sr2+ exchange isotherm. The thermodynamic equilibria for these cations were compared by using Kielland plots evaluated from the isotherms. PMID:15984251

  15. Number concentration and chemical composition of ultrafine and nanoparticles from WTE (waste to energy) plants.

    PubMed

    Cernuschi, Stefano; Giugliano, Michele; Ozgen, Senem; Consonni, Stefano

    2012-03-15

    Stack field testing at four municipal waste-to-energy (WTE) plants was conducted to investigate total number concentrations and size distributions in a size range extended towards the evaluation of ultrafine (UFP) and nanoparticle (NP) fractions with diameters smaller than 100nm and 50nm, respectively. Measurements were performed with a specifically designed sampling line, equipped with a dilution system and a particle counting device for measuring both primary particles in raw flue gases at stack conditions and the contributions of condensable origin, arising from their cooling and dilution immediately following stack release into the atmosphere. Average concentration levels detected ranged between 5×10(3)-6×10(5)cm(-3): for all sampling conditions, ultrafine fractions largely prevailed in number size distributions, with average diameters constantly located in the nanoparticle size range. Stack concentrations appeared to be influenced by the design and process configuration of flue gas cleaning systems, with most significant effects related to the presence of wet scrubbing units and the baghouse operating temperature of dry removal processes. Chemical speciation (i.e., trace metals, anions and cations, carbonaceous compounds) of size-resolved particulate fractions was performed on one of the plants. NP and UFP composition was essentially in accordance with the most important fuel and combustion process characteristics: in particular, the presence of chlorides and metal species was consistent with the respective waste feed content and their expected behavior during combustion and flue gas cleaning processes. PMID:22326138

  16. Microstructure and mechanical properties of an ultrafine Ti–Si–Nb alloy

    DOE PAGESBeta

    Cao, G. H.; Jian, G. Y.; Liu, N.; Zhang, W. H.; Russell, A. M.; Gerthsen, D.

    2015-08-19

    Nb-modified ultrafine Ti–Si eutectic alloy was made by cold crucible levitation melting, tested in compression at room temperature, and characterized by electron microscopy. Compression tests of (Ti86.5Si13.5)97Nb3 specimens measured an ultimate compressive strength of 1180 MPa and a compressive plastic strain of 12%, both of which are higher than in eutectic Ti86.5Si13.5 alloy. Electron microscopy showed that the Ti–Si–Nb alloy had a bimodal microstructure with micrometer-scale primary α-Ti dendrites distributed in an ultrafine eutectic (α-Ti + Ti5Si3) matrix. The enhanced ductility is attributed to the morphology of the phase constituents and to the larger lattice mismatches between α-Ti and Ti5Si3 phases caused by the Nb addition. Furthermore, the crystallographic orientation relationship of Ti5Si3 with α-Ti is (more » $$1\\bar{1}00$$ [$$\\overline{11}$$26]Ti5Si3∥($$01\\bar{1}1$$)[5$$\\overline{143}$$] α–Τi.« less

  17. Microstructure and mechanical properties of an ultrafine Ti–Si–Nb alloy

    SciTech Connect

    Cao, G. H.; Jian, G. Y.; Liu, N.; Zhang, W. H.; Russell, A. M.; Gerthsen, D.

    2015-08-19

    Nb-modified ultrafine Ti–Si eutectic alloy was made by cold crucible levitation melting, tested in compression at room temperature, and characterized by electron microscopy. Compression tests of (Ti86.5Si13.5)97Nb3 specimens measured an ultimate compressive strength of 1180 MPa and a compressive plastic strain of 12%, both of which are higher than in eutectic Ti86.5Si13.5 alloy. Electron microscopy showed that the Ti–Si–Nb alloy had a bimodal microstructure with micrometer-scale primary α-Ti dendrites distributed in an ultrafine eutectic (α-Ti + Ti5Si3) matrix. The enhanced ductility is attributed to the morphology of the phase constituents and to the larger lattice mismatches between α-Ti and Ti5Si3 phases caused by the Nb addition. Furthermore, the crystallographic orientation relationship of Ti5Si3 with α-Ti is ($1\\bar{1}00$ [$\\overline{11}$26]Ti5Si3∥($01\\bar{1}1$)[5$\\overline{143}$] α–Τi.

  18. Stability of ultrafine lamellar structures during aging in two-phase {gamma}-TiAl alloys

    SciTech Connect

    Maziasz, P.J.; Liu, C.T.; Wright, J.L.

    1997-08-01

    Two-phase {gamma}-tail alloys such as PM Ti-47Al-2Cr-2Nb or Ti-47Al- 2Cr-1Nb-Ta hot extruded above the {alpha}-transus temperature have unique refined-colony/ultrafine lamellar structures. These lamellar microstructures consist of very fine laths of the {gamma} and {alpha}{sub 2} phases, with average interlamellar spacings of 100 nm and {alpha}{sub 2}-{alpha}{sub 2} spacings of 200 nm, and are dominated by {gamma}/{alpha}{sub 2} interfaces. This ultrafine lamellar structure remains stable during 900 C heat treatment for 2 h, but becomes unstable after 4 h at 982 C. This structure remains stable in both alloys after aging for >5000 h at 800 C but disappears completely at 1000 C. Continuous coarsening begins with dissolution of fine {alpha}{sub 2} lamellea. The aged Ta-modified alloy shows similar lamellar coarsening behavior within the colonies but has more discontinuous coarsening of the intercolony {gamma} with new precipitation of coarse {alpha}{sub 2} and {beta} phase particles. Analytical electron microscopy show that changes in {alpha}{sub 2} phase composition correlate with microstructural instability.

  19. Impacts of freeway traffic conditions on in-vehicle exposure to ultrafine particulate matter

    NASA Astrophysics Data System (ADS)

    Bigazzi, Alexander Y.; Figliozzi, Miguel A.

    2012-12-01

    There is evidence of adverse health impacts from human exposure to traffic-related ultrafine particulate matter pollution. As more commuters are spending a significant portion of their daily routine inside vehicles, it is increasingly relevant to study exposure levels to harmful pollutants inside the vehicle microenvironment. This study is one of the first research efforts to combine detailed freeway traffic data (at 20 s intervals) and in-vehicle ultrafine particulate (UFP) exposure data under varying vehicle ventilation conditions. Results show that due to negative correlation between traffic speed and density, traffic states have a small but significant impact on in-vehicle UFP concentrations, highest in high traffic flow-high speed conditions or in high traffic density-low speed conditions. Vehicle cabin barrier effects are the primary determinant of in-vehicle exposure concentrations, providing 15% protection with the windows down, 47% protection with the windows up and the vent open, and 83-90% protection with the windows up and the vent closed (more with the air conditioning on). Unique results from this study include the dominance of ventilation over traffic effects on UFP and the non-linear relationships between traffic variables and UFP concentrations. The results of this research have important implications for exposure modeling and potential exposure mitigation strategies.

  20. Analysis and experiments on thermal plasma processing for ultrafine powder synthesis of aluminium nitride

    SciTech Connect

    Ahn, H.; Hur, M.; Hong, S.H.

    1996-12-31

    Plasma synthesis experiments for producing ultrafine powders of aluminum nitride (AlN) are carried out using a non-transferred dc plasma torch of which jet flame can vaporize the aluminum powders injected into it to make the chemical reaction with nitrogen gas. For predicting the optimum processing parameters (the size, injected location and velocity of Al powders, and the ratio of nitrogen to argon arc gases), the trajectory and the evaporation state of an Al particle arc found by solving momentum and heat transfer equations. In addition, equilibrium chemical compositions are analyzed by the Gibbs free-energy minimization method to know the temperatures at which AlN synthesis occurs dominantly. A synthesis system consisting of a plasma torch, a reactor and a quenching chamber has been built for synthesis and quenching process of ultrafine powders of AlN. A fully-saturated fractional factorial test is employed to determine optimum process conditions for input power to the torch and flow rates of arc, carrier and reaction gases.

  1. Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions

    DOE PAGESBeta

    El-atwani, O.; Hattar, Khalid Mikhiel; Hinks, J. A.; Greaves, G.; Harilal, S. S.; Hassanein, A.

    2014-12-25

    We investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. Moreover,more » at energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. Finally, we discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formation.« less

  2. Helium bubble formation in ultrafine and nanocrystalline tungsten under different extreme conditions

    NASA Astrophysics Data System (ADS)

    El-Atwani, O.; Hattar, K.; Hinks, J. A.; Greaves, G.; Harilal, S. S.; Hassanein, A.

    2015-03-01

    We have investigated the effects of helium ion irradiation energy and sample temperature on the performance of grain boundaries as helium sinks in ultrafine grained and nanocrystalline tungsten. Irradiations were performed at displacement and non-displacement energies and at temperatures above and below that required for vacancy migration. Microstructural investigations were performed using Transmission Electron Microscopy (TEM) combined with either in-situ or ex-situ ion irradiation. Under helium irradiation at an energy which does not cause atomic displacements in tungsten (70 eV), regardless of temperature and thus vacancy migration conditions, bubbles were uniformly distributed with no preferential bubble formation on grain boundaries. At energies that can cause displacements, bubbles were observed to be preferentially formed on the grain boundaries only at high temperatures where vacancy migration occurs. Under these conditions, the decoration of grain boundaries with large facetted bubbles occurred on nanocrystalline grains with dimensions less than 60 nm. We discuss the importance of vacancy supply and the formation and migration of radiation-induced defects on the performance of grain boundaries as helium sinks and the resulting irradiation tolerance of ultrafine grained and nanocrystalline tungsten to bubble formation.

  3. Microstructural evolution in ultra-fine grained copper processed by severe plastic deformation

    NASA Astrophysics Data System (ADS)

    Mishra, Anuj

    Equal Channel Angular Pressing (ECAP) is a severe plastic deformation technique that was used to produce ultra-fine grained copper. The microstructure was optimized using different deformation sequences. A steady state grain size of 200--500 nm was routinely obtained after eight passes (with an effective strain of ˜1 per pass). This resulted in a random texture evidenced by EBSD results. The mechanical response was obtained under quasi-static and dynamic conditions. The evolution of microstructure upon repeated ECAP passes was characterized by TEM and EBSD techniques. The features of grain refinement process were captured using analytical models. The minimum grain size obtained, 200--500 nm, was quantitatively explained by means of grain boundary rotation and grain boundary mobility calculations at the temperature reached in deformation process (˜360 K). The ultra-fine grained structure produced in Cu by ECAP was found to be thermally unstable. The microstructure recrystallized upon being dynamically deformed due to the adiabatic temperature rise imparted by plastic deformation. This was observed in three modes of high-strain rate plastic deformation experiments: cylindrical and hat-shaped specimens in Hopkinson bar experiments and cylindrical specimens in reverse Taylor impact experiments.

  4. Mineralogical characterization of ambient fine/ultrafine particles emitted from Xuanwei C1 coal combustion

    NASA Astrophysics Data System (ADS)

    Lu, Senlin; Hao, Xiaojie; Liu, Dingyu; Wang, Qiangxiang; Zhang, Wenchao; Liu, Pinwei; Zhang, Rongci; Yu, Shang; Pan, Ruiqi; Wu, Minghong; Yonemochi, Shinich; Wang, Qingyue

    2016-03-01

    Nano-quartz in Xuanwei coal, the uppermost Permian (C1) coal deposited in the northwest of Yuanan, China, has been regarded as one of factors which caused high lung cancer incidence in the local residents. However, mineralogical characterization of the fine/ultrafine particles emitted from Xuanwei coal combustion has not previously been studied. In this study, PM1 and ultrafine particles emitted from Xuanwei coal combustion were sampled. Chemical elements in the ambient particles were analyzed by inductively coupled plasma mass spectrometry (ICP-MS), and mineralogical characterization of these ambient particles was investigated using scanning electronic microscopy (SEM/EDX) and transmission electronic microscopy, coupled with energy-dispersive spectroscopy (TEM/EDX). Our results showed that the size distribution of mineral particles from the coal combustion emissions ranged from 20 to 200 nm. Si-containing particles and Fe-containing particles accounted for 50.7% of the 150 individual particles measured, suggesting that these two types of particles were major minerals in the ambient particles generally. The nano-mineral particles were identified as quartz (SiO2) and gypsum (CaSO4) based on their crystal parameters and chemical elements. Additionally, there also existed unidentified nano-minerals. Armed with these data, toxicity assessments of the nano-minerals will be carried out in a future study.

  5. [Experimental study on the size spectra and emission factor of ultrafine particle from coal combustion].

    PubMed

    Sun, Zai; Yang, Wen-jun; Xie, Xiao-fang; Chen, Qiu-fang; Cai, Zhi-liang

    2014-12-01

    The emission characteristics of ultrafine particles released from pulverized coal combustion were studied, the size spectra of ultrafine particles (5.6-560 nm) were measured with FMPS (fast mobility particle sizer) on a self-built aerosol experiment platform. Meanwhile, a particle dynamic evolution model was established to obtain the particle deposition rate and the emission rate through the optimized algorithm. Finally, the emission factor was calculated. The results showed that at the beginning of particle generation, the size spectra were polydisperse and complex, the initial size spectra was mainly composed of three modes including 10 nm, 30-40 nm and 100-200 nm. Among them, the number concentration of mode around 10 nm was higher than those of other modes, the size spectrum of around 100-200 nm was lognormal distributed, with a CMD (count median diameter) of around 16 nm. Then, as time went on, the total number concentration was decayed by exponential law, the CMD first increased and then tended to be stable gradually. The calculation results showed that the emission factor of particles from coal combustion under laboratory condition was (5.54 x 10(12) ± 2.18 x 10(12)) unit x g(-1). PMID:25826918

  6. Number size distribution of fine and ultrafine fume particles from various welding processes.

    PubMed

    Brand, Peter; Lenz, Klaus; Reisgen, Uwe; Kraus, Thomas

    2013-04-01

    Studies in the field of environmental epidemiology indicate that for the adverse effect of inhaled particles not only particle mass is crucial but also particle size is. Ultrafine particles with diameters below 100 nm are of special interest since these particles have high surface area to mass ratio and have properties which differ from those of larger particles. In this paper, particle size distributions of various welding and joining techniques were measured close to the welding process using a fast mobility particle sizer (FMPS). It turned out that welding processes with high mass emission rates (manual metal arc welding, metal active gas welding, metal inert gas welding, metal inert gas soldering, and laser welding) show mainly agglomerated particles with diameters above 100 nm and only few particles in the size range below 50 nm (10 to 15%). Welding processes with low mass emission rates (tungsten inert gas welding and resistance spot welding) emit predominantly ultrafine particles with diameters well below 100 nm. This finding can be explained by considerably faster agglomeration processes in welding processes with high mass emission rates. Although mass emission is low for tungsten inert gas welding and resistance spot welding, due to the low particle size of the fume, these processes cannot be labeled as toxicologically irrelevant and should be further investigated. PMID:23028013

  7. Mechanism of formation of composite CdS-ZnS ultrafine particles in reverse micelles

    SciTech Connect

    Sato, Hiroshi; Hirai, Takayuki; Komasawa, Isao

    1995-07-01

    The mechanism of formation of composite cadmium sulfide and zinc sulfide ultrafine particles (Cd{sub 1{minus}x}Zn{sub x}S) by simultaneous precipitation of cadmium sulfide and zinc sulfide in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles has been studied. The particle formation process was followed by the change in UV-visible absorption spectra. The effects of the reactant concentration, the molar ratio of cadmium to zinc ions, and the water content on the particle formation process were investigated. The resultant particles were richer in CdS than the feed composition of the cadmium to zinc ions in the reaction solution. The particle composition was found to be controlled by the solubility of the CdS and ZnS ultrafine particles. The particle coagulation process was analyzed on the basis of a statistical distribution of particles among the reverse micelles. The coagulation rate constant was controlled by the composition and the size of the particles and by the size of the reverse micelles.

  8. The structure and magnetic properties of ultrafine iron particles with oxide layer

    SciTech Connect

    Gavrilyuk, A.G.; Sadykov, R.A.

    1994-12-01

    Ultrafine iron particles (UFIPs) are promising as materials for high-density magnetic recording and ferrofluids because the superparamagnetic state in these particles develops at smaller particle sizes than in conventional magnetic materials. The basic obstacle to producing UFIPs is their high reactivity, which leads to strong oxidation of these particles. Given this, effort is being devoted to extending chemical stabilization to iron particles of the smallest size possible. One possible approach involves the formation of a thin passivating oxide layer on iron particles [1-3], for example, by atmospheric-air oxidation or by oxidation in a special atmosphere. This results in the formation of an interesting structure - an ultrafine particle whose magnetic properties exhibit a marked variation from its center to the surface. The UFIP oxidized at room temperature was shown to consist of an unoxidized {alpha}-Fe core with an average diameter of 110 {Angstrom} and a 45-{Angstrom}-thick oxide layer with a spinel-type structure. The hyperfine magnetic field at the particle core coincides with the field in an infinite sample, whereas in the oxide layer, the average magnetic field was lower. Magnetic interaction between the central region of the UFIP and the oxide layer was found to suppress superparamagnetism and to result in development of a hyperfine structure in the Moessbauer subspectrum of the oxide layer. The observed shape of the Moessbauer spectrum is related to the surface state of the oxide phase and, to some extent, to the presence of defects.

  9. Thickening of ultrafine coal-water slurries in a solid-bowl centrifuge

    SciTech Connect

    Pinkerton, A.P.; Klima, M.S.; Morrison, J.L.; Miller, B.G.

    1999-07-01

    As part of a study being conducted for the Electric Power Research Institute's (EPRI's) Upgraded Coal Interest Group (UCIG) to evaluate ultrafine coal dewatering technologies, testing was carried out to investigate the use of a solid-bowl (high-g) centrifuge for thickening ultrafine coalwater slurries. The objective of this study was to increase the solids concentration to a level suitable for use as a coal-water slurry fuel, while maximizing overall solids recovery. Feed material was collected from the combined discharge (centrate) streams from several screen-bowl centrifuges. These devices are currently being used in a commercial coal cleaning facility to dewater the clean coal product from a froth flotation circuit. Current plant practice is to discharge the centrate to settling ponds. The screen bowl centrate averages 5% solids by weight and contains nearly 60% material finer than 10 {mu}m. The current study examined the effects of operating conditions on centrifuge performance. The test conditions included centrifuge bowl and scroll speeds and volumetric feed rate. In addition to thickening, some cleaning was also achieved, because the finest particles (e.g. < 3 {micro}m), which contained a large percentage of liberated clays, were removed with the bulk of the water. The centrifuge products were analyzed for solids concentration, particle size distribution, and ash content. Size selectivity curves were also used to evaluate centrifuge performance.

  10. Exposure of Children to Ultrafine Particles in Primary Schools in Portugal.

    PubMed

    Rufo, João Cavaleiro; Madureira, Joana; Paciência, Inês; Slezakova, Klara; Pereira, Maria do Carmo; Pereira, Cristiana; Teixeira, João Paulo; Pinto, Mariana; Moreira, André; Fernandes, Eduardo de Oliveira

    2015-01-01

    Children spend a large part of their time at schools, which might be reflected as chronic exposure. Ultrafine particles (UFP) are generally associated with a more severe toxicity compared to fine and coarse particles, due to their ability to penetrate cell membranes. In addition, children tend to be more susceptible to UFP-mediated toxicity compared to adults, due to various factors including undeveloped immune and respiratory systems and inhalation rates. Thus, the purpose of this study was to determine indoor UFP number concentrations in Portuguese primary schools. Ultrafine particles were sampled between January and March 2014 in 10 public primary schools (35 classrooms) located in Porto, Portugal. Overall, the average indoor UFP number concentrations were not significantly different from outdoor concentrations (8.69 × 10(3) vs. 9.25 × 10(3) pt/cm(3), respectively; considering 6.5 h of indoor occupancy). Classrooms with distinct characteristics showed different trends of indoor UFP concentrations. The levels of carbon dioxide were negatively correlated with indoor UFP concentrations. Occupational density was significantly and positively correlated with UFP concentrations. Although the obtained results need to be interpreted with caution since there are no guidelines for UFP levels, special attention needs to be given to source control strategies in order to reduce major particle emissions and ensure good indoor air quality. PMID:26167756

  11. Consecutively preparing d-xylose, organosolv lignin, and amorphous ultrafine silica from rice husk.

    PubMed

    Zhang, Hongxi; Ding, Xuefeng; Wang, Zichen; Zhao, Xu

    2014-01-01

    Rice husk is an abundant agricultural by-product reaching the output of 80 million tons annually in the world. The most common treatment method of rice husk is burning or burying, which caused serious air pollution and resource waste. In order to solve this problem, a new method is proposed to comprehensively utilize the rice husk in this paper. Firstly, the D-xylose was prepared from the semicellulose via dilute acid hydrolysis. Secondly, the lignin was separated via organic solvent pulping from the residue. Finally, the amorphous ultrafine silica was prepared via pyrolysis of the residue produced in the second process. In this way, the three main contents of rice husk (semicellulose, lignin, and silica) are consecutively converted to three fine chemicals, without solid waste produced. The yields of D-xylose and organosolv lignin reach 58.2% and 58.5%, respectively. The purity and specific surface of amorphous ultrafine silica reach 99.92% and 225.20 m(2)/g. PMID:25140120

  12. Synthesis of ultrafine Si3N4 powder in RF-RF plasma

    SciTech Connect

    Sato, Michitaka; Nishio, Hiroaki

    1991-10-01

    A newly designed plasma-CVD apparatus mounted with the RF-RF type plasma torch was introduced to synthesize ultrafine powders of silicon nitride (Si3N4). The RF-RF plasma system (the combination of a main (lower) and controlling (upper) RF plasma) improved the stability of simple RF plasma and solved the impurity problem of dc-RF hybrid plasma. The reaction of SiCl4 and NH3, which were radially injected into the tail flames of the upper and lower plasmas, respectively, yielded near-stoichiometric amorphous powders of Si3N4. The nitrogen content in the products largely depended on the flow rate of the quenching gas, a mixture of NH3 (reactant) and H2. The oxygen content and metal impurities are 2-3 wt pct and less than 200 ppm, respectively. The powder particles had an average diameter of about 15 nm with a narrow size distribution, and showed extreme air sensitivity. Conspicuous crystallazation and particle growth occurred when heated at temperatures above 1400 C. These results suggested that the RF-RF system was a potential reactor for the synthesis of ultrafine powders with excellent sinterability at relatively low temperatures. 9 refs.

  13. Superior H2 production by hydrophilic ultrafine Ta2O5 engineered covalently on graphene.

    PubMed

    Mao, Lin; Zhu, Shenmin; Ma, Jun; Shi, Dian; Chen, Yixin; Chen, Zhixin; Yin, Chao; Li, Yao; Zhang, Di

    2014-05-30

    A H2O2-mediated hydrothermal method was developed for the fabrication of hydrophilic Ta2O5/graphene composite. The composite shows a superior H2 productivity, up to 30 mmol g(-1) h(-1) when used as a photocatalyst for water splitting, corresponding to an apparent quantum efficiency of 33.8% at 254 nm. This superior performance is due to the hydrophilic nature of the composite and more importantly due to the ultrafine Ta2O5 nanoparticles (about 4.0 ± 1.5 nm) which are covalently bonded with the conductive graphene. The hydrophilic property of the composite is attributed to the use of H2O2 in the hydrothermal process. The ultrafine size of the Ta2O5 particles which are covalently bonded with the graphene sheets is attributed to the use of sonication in the synthesis process. Furthermore, the hydrophilic Ta2O5/Gr composite is durable, which is beneficial to long term photocatalysis. The strategy reported here provides a new approach to designing photocatalysts with superior performance for H2 production. PMID:24787652

  14. Exploring novel ultrafine Eri silk bioscaffold for enzyme stabilisation in cellobiose hydrolysis.

    PubMed

    Verma, Madan L; Rajkhowa, Rangam; Wang, Xungai; Barrow, Colin J; Puri, Munish

    2013-10-01

    The suitability of optimised ultrafine Eri silk microparticles as novel enzyme supports was studied for potential application in biofuel production. β-glucosidase (BGL) from Aspergillus niger was immobilised on Eri silk fibrion particles via an adsorption method resulting in a 62% immobilisation yield. Soluble and immobilised enzymes exhibited pH-optima at pH 4.0 and 5.0, respectively with optimum activity at 60°C. The Michaelis constant (K(M)) was 0.16 and 0.27 mM for soluble and immobilised BGL respectively. The immobilisation support has a protective effect on the enzyme by increasing rigidity; this is reflected by an increase in stability under thermal denaturation at 70°C. Immobilised enzyme retained more than 50% of initial activity for up to eight cycles. Maximum cellobiose hydrolysis by immobilised BGL was achieved at 20 h. Crystalline ultrafine Eri silk particles were found to be a promising viable, environmentally sound and stable matrix for binding BGL for cellobiose hydrolysis. PMID:23462595

  15. Correlation between the Mechanical Properties and Structural Characteristics of Different Fiber Posts Systems.

    PubMed

    Novais, Veridiana Resende; Rodrigues, Renata Borges; Simamoto Júnior, Paulo Cezar; Lourenço, Correr-Sobrinho; Soares, Carlos José

    2016-01-01

    The aim of this study was to evaluate the flexural strength and flexural modulus of different fiber-reinforcement composite (FRC) posts and determine the correlation between mechanical properties and structural characteristics. Eleven brands of fiber posts were analyzed (n=10): Exacto Cônico (Angelus), DT Light SL (VDW), RelyX Fiber Post (3M-Espe), Glassix Radiopaque (Nordim), Para Post Fiber White (Coltène), FRC Postec Plus (Ivoclar), Aestheti-Plus Post (Bisco), Superpost Cônico Estriado (Superdont), Superpost Ultrafine (Superdont), Reforpost (Angelus), and White Post DC (FGM). The posts were loaded in three-point bending test to calculate the flexural strength and flexural modulus using a mechanical testing machine (EMIC 2000 DL) at 0.5 mm/min. Data were submitted to one-way ANOVA and Scott-Knot test (p<0.05). The cross-sections of the posts were examined by scanning electron microscopy (SEM). Correlation between the mechanical properties and each of the structural variables was calculated by Pearson's correlation coefficients (p<0.05). The flexural strength values ranged from 493 to 835 MPa and were directly correlated with the fiber/matrix ratio (p=0.011). The flexural modulus ranged from 4500 to 8824 MPa and was inversely correlated with the number of fibers per mm2 of post (p<0.001). It was concluded that the structural characteristics significantly affected the properties of the FRC posts. The structural characteristic and mechanical properties of fiber glass posts are manufacture-dependent. A linear correlation between flexural strength and fiber/matrix ratio, as well as the flexural modulus and the amount of fiber was found. PMID:27007345

  16. Ultrafine particles near a major roadway in Raleigh, North Carolina: downwind attenuation and correlation with traffic-related pollutants

    EPA Science Inventory

    Ultrafine particles (UFPs, diameter <100 run) emitted by traffic are a potential direct health threat to nearby populations and may additionally act as a tracer for co-emitted pollutants. During summertime in Raleigh, North Carolina, UFPs were simultaneously measured upwind and d...

  17. Mast cells contribute to alterations in vascular reactivity and exacerbation of ischemia reperfusion injury following ultrafine PM exposure

    EPA Science Inventory

    Increased ambient fine particulate matter (FPM) concentrations are associated with increased risk for short-term and long-term adverse cardiovascular events. Ultrafine PM (UFPM) due to its size and increased surface area might be particularly toxic. Mast cells are well recognized...

  18. Measurement and capture of fine and ultrafine particles from a pilot-scale pulverized coal combustor with an electrostatic precipitator.

    PubMed

    Li, Ying; Suriyawong, Achariya; Daukoru, Michael; Zhuang, Ye; Biswas, Pratim

    2009-05-01

    Experiments were carried out in a pilot-scale pulverized coal combustor at the Energy and Environmental Research Center (EERC) burning a Powder River Basin (PRB) subbituminous coal. A scanning mobility particle sizer (SMPS) and an electrical low-pressure impactor (ELPI) were used to measure the particle size distributions (PSDs) in the range of 17 nm to 10 microm at the inlet and outlet of the electrostatic precipitator (ESP). At the ESP inlet, a high number concentration of ultrafine particles was found, with the peak at approximately 75 nm. A trimodal PSD for mass concentration was observed with the modes at approximately 80-100 nm, 1-2 microm, and 10 microm. The penetration of ultrafine particles through the ESP increased dramatically as particle size decreased below 70 nm, attributable to insufficient or partial charging of the ultrafine particles. Injection of nanostructured fine-particle sorbents for capture of toxic metals in the flue gas caused high penetration of the ultrafine particles through the ESP. The conventional ESP was modified to enhance charging using soft X-ray irradiation. A slipstream of flue gas was introduced from the pilot-scale facility and passed through this modified ESP. Enhancement of particle capture was observed with the soft X-ray irradiation when moderate voltages were used in the ESP, indicating more efficient charging of fine particles. PMID:19583155

  19. CONCENTRATIONS OF ULTRAFINE, FINE AND PM2.5 PARTICLES IN THREE EUROPEAN CITIES. (R827354C002)

    EPA Science Inventory

    Total number concentrations, number concentrations of ultrafine (0.01¯0.1 small mu, Greekm) and accumulation (0.1¯0.5 INCREASED IL-8 AND IL-6 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES

    EPA Science Inventory

    INCREASED IL-6 AND IL-8 EXPRESSION IN HUMAN AIRWAY EPITHELIAL CELLS EXPOSED TO CARBON ULTRAFINE PARTICLES.
    R Silbajoris1, A G Lenz2, I Jaspers3, J M Samet1. 1NHEERL, USEPA, RTP, NC, USA; 2GSF-Institute for Inhalation Biology, Neuherberg, Germany; 3 CEMLB, UNC-CH, Chapel Hill, ...

  1. Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH) in Brisbane, Queensland (Australia): Study Design and Implementation

    PubMed Central

    Ezz, Wafaa Nabil; Mazaheri, Mandana; Robinson, Paul; Johnson, Graham R.; Clifford, Samuel; He, Congrong; Morawska, Lidia; Marks, Guy B.

    2015-01-01

    Ultrafine particles are particles that are less than 0.1 micrometres (µm) in diameter. Due to their very small size they can penetrate deep into the lungs, and potentially cause more damage than larger particles. The Ultrafine Particles from Traffic Emissions and Children’s Health (UPTECH) study is the first Australian epidemiological study to assess the health effects of ultrafine particles on children’s health in general and peripheral airways in particular. The study is being conducted in Brisbane, Australia. Continuous indoor and outdoor air pollution monitoring was conducted within each of the twenty five participating school campuses to measure particulate matter, including in the ultrafine size range, and gases. Respiratory health effects were evaluated by conducting the following tests on participating children at each school: spirometry, forced oscillation technique (FOT) and multiple breath nitrogen washout test (MBNW) (to assess airway function), fraction of exhaled nitric oxide (FeNO, to assess airway inflammation), blood cotinine levels (to assess exposure to second-hand tobacco smoke), and serum C-reactive protein (CRP) levels (to measure systemic inflammation). A pilot study was conducted prior to commencing the main study to assess the feasibility and reliably of measurement of some of the clinical tests that have been proposed for the main study. Air pollutant exposure measurements were not included in the pilot study. PMID:25648226

  2. CONTINUOUS MONITORING OF ULTRAFINE, FINE, AND COARSE PARTICLES IN A RESIDENCE FOR 18 MONTHS IN 1999-2000

    EPA Science Inventory

    Continuous monitors were employed for 18 months in an occupied townhouse to measure ultrafine, fine, and coarse particles; air change rates; wind speed and direction; temperature; and relative humidity (RH). A main objective was to document short-term and long-term variation in...

  3. Effect of Mitochondrial Oxidative Stress and Age on the Signaling Pathway of Ultrafine Particulate Matter Exposure in Murine Aorta

    EPA Science Inventory

    Epidemiological studies have linked ultrafine particulate matter (PM) exposure and adverse cardiovascular events. PM-induced oxidative stress is believed to be a key mechanism contributing to the adverse short-term vascular effects of air pollution exposure. Advanced age is one ...

  4. STUDY OF ULTRAFINE PARTICLES NEAR A MAJOR HIGHWAY WITH HEAVY-DUTY DIESEL TRAFFIC. (R827352C011)

    EPA Science Inventory

    Motor vehicle emissions usually constitute the most significant source of ultrafine particles (diameter <0.1 small mu, Greekm) in an urban environment. Zhu et al. (J. Air Waste Manage. As...

  5. Synthesis of branched, nano channeled, ultrafine and nano carbon tubes from PET wastes using the arc discharge method

    SciTech Connect

    Joseph Berkmans, A.; Jagannatham, M.; Priyanka, S.; Haridoss, Prathap

    2014-11-15

    Highlights: • Polymer wastes are converted into ultrafine and nano carbon tubes and spheres. • Simple process with a minimal processing time. • It is a catalyst free and solvent free approach. • This process forms branched ultrafine carbon tubules with nano channels. - Abstract: Upcycling polymer wastes into useful, and valuable carbon based materials, is a challenging process. We report a novel catalyst-free and solvent-free technique for the formation of nano channeled ultrafine carbon tubes (NCUFCTs) and multiwalled carbon nanotubes (MWCNTs) from polyethylene terephthalate (PET) wastes, using rotating cathode arc discharge technique. The soot obtain from the anode contains ultrafine and nano-sized solid carbon spheres (SCS) with a mean diameter of 221 nm and 100 nm, respectively, formed at the lower temperature region of the anode where the temperature is approximately 1700 °C. The carbon spheres are converted into long “Y” type branched and non-branched NCUFCTs and MWCNTs at higher temperature regions where the temperature is approximately 2600 °C, with mean diameters of 364 nm and 95 nm, respectively. Soot deposited on the cathode is composed of MWCNTs with a mean diameter of 20 nm and other nanoparticles. The tubular structures present in the anode are longer, bent and often coiled with lesser graphitization compared to the nanotubes in the soot on the cathode.

  6. FORMATION OF FINE PARTICLES FROM RESIDUAL OIL COMBUSTION: REDUCING ULTRAFINE NUCLEI THROUGH THE ADDITION OF INORGANIC SORBENT

    EPA Science Inventory

    The paper gives results of an investigation, using an 82-kW-rated laboratory-scale refractory-lined combustor, of the characteristics of particulate matter emitted from residual oil combustion and the reduction of ultrafine nuclei by postflame sorbent injection. Without sorbent a...

  7. Specialty optical fibers: revisited

    NASA Astrophysics Data System (ADS)

    Romaniuk, Ryszard S.

    2011-10-01

    The paper contains description of chosen aspects of analysis and design of tailored optical fibers. By specialty optical fibers we understand here the fibers which have complex construction and which serve for the functional processing of optical signal rather than long distance transmission. Thus, they are called also instrumentation optical fibers. The following issues are considered: transmission properties, transformation of optical signal, fiber characteristics, fiber susceptibility to external reactions. The technology of tailored optical fibers offers a wider choice of the design tools for the fiber itself, and then various devices made from these fiber, than classical technology of communication optical fibers. The consequence is different fiber properties, nonstandard dimensions and different metrological problems. The price to be paid for wider design possibilities are bigger optical losses of these fibers and weaker mechanical properties, and worse chemical stability. These fibers find their applications outside the field of telecommunications. The applications of instrumentation optical fibers combine other techniques apart from the photonics ones like: electronic, chemical and mechatronic.

  8. Medicated Janus fibers fabricated using a Teflon-coated side-by-side spinneret.

    PubMed

    Yu, Deng-Guang; Yang, Chen; Jin, Miao; Williams, Gareth R; Zou, Hua; Wang, Xia; Bligh, S W Annie

    2016-02-01

    A family of medicated Janus fibers that provides highly tunable biphasic drug release was fabricated using a side-by-side electrospinning process employing a Teflon-coated parallel spinneret. The coated spinneret facilitated the formation of a Janus Taylor cone and in turn high quality integrated Janus structures, which could not be reliably obtained without the Teflon coating. The fibers prepared had one side consisting of polyvinylpyrrolidone (PVP) K60 and ketoprofen, and the other of ethyl cellulose (EC) and ketoprofen. To modulate and tune drug release, PVP K10 was doped into the EC side in some cases. The fibers were linear and had flat morphologies with an indent in the center. They provide biphasic drug release, with the PVP K60 side dissolving very rapidly to deliver a loading dose of the active ingredient, and the EC side resulting in sustained release of the remaining ketoprofen. The addition of PVP K10 to the EC side was able to accelerate the second stage of release; variation in the dopant amount permitted the release rate and extent this phase to be precisely tuned. These results offer the potential to rationally design systems with highly controllable drug release profiles, which can complement natural biological rhythms and deliver maximum therapeutic effects. PMID:26674839

  9. Electrospun fibers as potential carrier systems for enhanced drug release of perphenazine.

    PubMed

    Bruni, Giovanna; Maggi, Lauretta; Tammaro, Loredana; Lorenzo, Rosadele Di; Friuli, Valeria; D'Aniello, Sharon; Maietta, Mariarosa; Berbenni, Vittorio; Milanese, Chiara; Girella, Alessandro; Marini, Amedeo

    2016-09-10

    Solubility represents an important challenge for formulation of drugs, because the therapeutic efficacy of a drug depends on the bioavailability and ultimately on its solubility. Low aqueous solubility is one of the main issues related with formulation design and development of new molecules. Many drug molecules present bioavailability problems due to their poor solubility. For this reason there is a great interest in the development of new carrier systems able to enhance the dissolution of poorly water-soluble drugs. In this work, fibers containing an insoluble model drug and prepared by an electrospinning method, are proposed and evaluated to solve this problem. Two hydrophilic polymers, polyvinylpyrrolidone (Plasdone® K29/32) and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (Soluplus®) were used to increase the water solubility of perphenazine. The physico-chemical characterization suggests that the drug loaded in the fibers is in the amorphous state. Both polymeric carriers are effective to promote the drug dissolution rate in water, where this active pharmaceutical ingredient is insoluble, due to the fine dispersion of the drug into the polymeric matrices, obtained with this production technique. In fact, the dissolution profiles of the fibers, compared to the simple physical mixture of the two components, and to the reference commercial product Trilafon® 8mg tablets, show that a strong enhancement of the drug dissolution rate can be achieved with the electrospinning technique. PMID:27418562

  10. Bamboo leaf derived ultrafine Si nanoparticles and Si/C nanocomposites for high-performance Li-ion battery anodes.

    PubMed

    Wang, Lei; Gao, Biao; Peng, Changjian; Peng, Xiang; Fu, Jijiang; Chu, Paul K; Huo, Kaifu

    2015-09-01

    Silicon-based nanomaterials are promising anode materials in lithium-ion batteries (LIBs) due to their high theoretical capacity of 4200 mA h g(-1), more than 10 times that of commercial graphite. Si nanoparticles (NPs) with a diameter of or below 10 nm generally exhibit enhanced lithium storage properties due to their small size and large surface area. However, it is challenging to generate such ultrafine Si NPs by a facile and scalable method. This paper reports a scalable method to fabricate ultrafine Si NPs 5-8 nm in size from dead bamboo leaves (BLs) by thermally decomposing the organic matter, followed by magnesiothermic reduction in the presence of NaCl as a heat scavenger. The ultrafine Si NPs show a high capacity of 1800 mA h g(-1) at a 0.2 C (1 C = 4200 mA g(-1)) rate and are thus promising anode materials in lithium-ion batteries. To achieve better rate capability, the BLs-derived ultrafine Si NPs are coated with a thin amorphous carbon layer (Si@C) and then dispersed and embedded in a reduced graphene oxide (RGO) network to produce Si@C/RGO nanocomposites by a layer-by-layer assembly method. The double protection rendered by the carbon shell and RGO network synergistically yield structural stability, high electrical conductivity and a stable solid electrolyte interface during Li insertion/extraction. The Si@C/RGO nanocomposites show excellent battery properties with a high capacity of 1400 mA h g(-1) at a high current density of 2 C and remarkable rate performance with a capacity retention of 60% when the current density is increased 20 times from 0.2 to 4 C. This work provides a simple, low cost, and scalable approach enabling the use of BL waste as a sustainable source for the production of ultrafine Si NPs towards high-performance LIBs. PMID:26098990

  11. The effects on bronchial epithelial mucociliary cultures of coarse, fine, and ultrafine particulate matter from an underground railway station.

    PubMed

    Loxham, Matthew; Morgan-Walsh, Rebecca J; Cooper, Matthew J; Blume, Cornelia; Swindle, Emily J; Dennison, Patrick W; Howarth, Peter H; Cassee, Flemming R; Teagle, Damon A H; Palmer, Martin R; Davies, Donna E

    2015-05-01

    We have previously shown that underground railway particulate matter (PM) is rich in iron and other transition metals across coarse (PM10-2.5), fine (PM2.5), and quasi-ultrafine (PM0.18) fractions and is able to generate reactive oxygen species (ROS). However, there is little knowledge of whether the metal-rich nature of such particles exerts toxic effects in mucus-covered airway epithelial cell cultures or whether there is an increased risk posed by the ultrafine fraction. Monolayer and mucociliary air-liquid interface (ALI) cultures of primary bronchial epithelial cells (PBECs) were exposed to size-fractionated underground railway PM (1.1-11.1 µg/cm(2)) and release of lactate dehydrogenase and IL-8 was assayed. ROS generation was measured, and the mechanism of generation studied using desferrioxamine (DFX) and N-acetylcysteine (NAC). Expression of heme oxygenase-1 (HO-1) was determined by RT-qPCR. Particle uptake was studied by transmission electron microscopy. Underground PM increased IL-8 release from PBECs, but this was diminished in mucus-secreting ALI cultures. Fine and ultrafine PM generated a greater level of ROS than coarse PM. ROS generation by ultrafine PM was ameliorated by DFX and NAC, suggesting an iron-dependent mechanism. Despite the presence of mucus, ALI cultures displayed increased HO-1 expression. Intracellular PM was observed within vesicles, mitochondria, and free in the cytosol. The results indicate that, although the mucous layer appears to confer some protection against underground PM, ALI PBECs nonetheless detect PM and mount an antioxidant response. The combination of increased ROS-generating ability of the metal-rich ultrafine fraction and ability of PM to penetrate the mucous layer merits further research. PMID:25673499

  12. The Effects on Bronchial Epithelial Mucociliary Cultures of Coarse, Fine, and Ultrafine Particulate Matter From an Underground Railway Station

    PubMed Central

    Loxham, Matthew; Morgan-Walsh, Rebecca J.; Cooper, Matthew J.; Blume, Cornelia; Swindle, Emily J.; Dennison, Patrick W.; Howarth, Peter H.; Cassee, Flemming R.; Teagle, Damon A. H.; Palmer, Martin R.; Davies, Donna E.

    2015-01-01

    We have previously shown that underground railway particulate matter (PM) is rich in iron and other transition metals across coarse (PM10–2.5), fine (PM2.5), and quasi-ultrafine (PM0.18) fractions and is able to generate reactive oxygen species (ROS). However, there is little knowledge of whether the metal-rich nature of such particles exerts toxic effects in mucus-covered airway epithelial cell cultures or whether there is an increased risk posed by the ultrafine fraction. Monolayer and mucociliary air-liquid interface (ALI) cultures of primary bronchial epithelial cells (PBECs) were exposed to size-fractionated underground railway PM (1.1–11.1 µg/cm2) and release of lactate dehydrogenase and IL-8 was assayed. ROS generation was measured, and the mechanism of generation studied using desferrioxamine (DFX) and N-acetylcysteine (NAC). Expression of heme oxygenase-1 (HO-1) was determined by RT-qPCR. Particle uptake was studied by transmission electron microscopy. Underground PM increased IL-8 release from PBECs, but this was diminished in mucus-secreting ALI cultures. Fine and ultrafine PM generated a greater level of ROS than coarse PM. ROS generation by ultrafine PM was ameliorated by DFX and NAC, suggesting an iron-dependent mechanism. Despite the presence of mucus, ALI cultures displayed increased HO-1 expression. Intracellular PM was observed within vesicles, mitochondria, and free in the cytosol. The results indicate that, although the mucous layer appears to confer some protection against underground PM, ALI PBECs nonetheless detect PM and mount an antioxidant response. The combination of increased ROS-generating ability of the metal-rich ultrafine fraction and ability of PM to penetrate the mucous layer merits further research. PMID:25673499

  13. Ultrafine Angelica gigas Powder Normalizes Ovarian Hormone Levels and Has Antiosteoporosis Properties in Ovariectomized Rats: Particle Size Effect

    PubMed Central

    Choi, Kyeong-Ok; Lee, Inae; Paik, Sae-Yeol-Rim; Kim, Dong Eun; Lim, Jung Dae; Kang, Wie-Soo; Ko, Sanghoon

    2012-01-01

    Abstract The root of Angelica gigas (Korean angelica) is traditionally used to treat women's ailments that are caused by an impairment of menstrual blood flow and cycle irregularities. This study evaluated the effect particle size of Korean angelica powder on its efficacy for treating estrogen-related symptoms of menopause. Initially, Korean angelica roots were pulverized into ultrafine powder, and orally administered to the rats at a concentration of 500 mg/kg body weight for 8 weeks. The effects of Korean angelica powder particle size on extraction yield, contents of bioactive compounds (decursin and decursinol angelate), levels of serum ovarian hormones (estradiol and progesterone), reproductive hormones (luteinizing hormone and follicle-stimulating hormone), and experimental osteoporosis parameters (mineral density, strength, and histological features) were determined. A significant increase (fivefold) in the contents of decursin and decursinol angelate in the extract of the ultrafine Korean angelica powder was observed compared to coarse Korean angelica powder. Rats were divided into sham-operated or ovariectomized (OVX) groups that were fed coarse (CRS) or ultrafine (UF) ground Korean angelica root. The serum levels of estradiol in the OVX_UF group were 19.2% and 54.1% higher than that of OVX_CRS group. Serum bone-alkaline phosphatase/total-alkaline phosphatase index in the OVX_UF group was half that of the OVX_CRS group. In addition, less trabecular bone loss and thick cortical areas were observed in rats administered ultrafine powder. Therefore, ultrafine grinding may enhance the bioactivity of herbal medicines and be especially useful when their extracted forms lose bioactivity during processing, storage, and oral intake. PMID:23039111

  14. The polyvinylpyrrolidone functionalized rGO/Bi2S3 nanocomposite as a near-infrared light-responsive nanovehicle for chemo-photothermal therapy of cancer

    NASA Astrophysics Data System (ADS)

    Dou, Ruixia; Du, Zhen; Bao, Tao; Dong, Xinghua; Zheng, Xiaopeng; Yu, Miao; Yin, Wenyan; Dong, Binbin; Yan, Liang; Gu, Zhanjun

    2016-06-01

    Recently, a combination of chemotherapy with photothermal therapy (PTT) has received great attention for the construction of a near infrared (NIR)-controlled drug-delivery system for synergistic treatment of cancer, ultimately resulting in the enhancement of the therapeutic efficacy of anticancer drugs. Here, we developed a novel system for synergistic cancer therapy based on bismuth sulfide (Bi2S3) nanoparticle-decorated graphene functionalized with polyvinylpyrrolidone (PVP) (named PVP-rGO/Bi2S3). The as-prepared PVP-rGO/Bi2S3 nanocomposite has a high storage capacity for anticancer drugs (~500% for doxorubicin (DOX)) and simultaneously has perfect photothermal conversion efficiency in the NIR region. The results of the in vitro accumulative drug release test manifests that the PVP-rGO/Bi2S3 nanocomposite could be applied as a dual pH- and NIR-responsive nanotherapeutic carrier for the controlled release of DOX from DOX-loaded PVP-rGO/Bi2S3 (PVP-rGO/Bi2S3@DOX). Moreover, the treatment of both cancer cells (including Hela, MCF-7, HepG2 and BEL-7402 cells) and BEL-7402 tumor-bearing mice with the PVP-rGO/Bi2S3@DOX complex followed by NIR laser irradiation produces significantly greater inhibition of cancer cell growth than the treatment with NIR irradiation alone or DOX alone, exhibiting a synergistic antitumor effect. Furthermore, due to the obvious NIR and X-ray absorption ability, the PVP-rGO/Bi2S3 nanocomposite could be employed as a dual-modal contrast agent for both photoacoustic tomography and X-ray computed tomography imaging. In addition to the good biocompatibility, the PVP-rGO/Bi2S3 nanocomposite paves a potential way for the fabrication of theranostic agents for dual-modal imaging-guided chemo-photothermal combined cancer therapy.Recently, a combination of chemotherapy with photothermal therapy (PTT) has received great attention for the construction of a near infrared (NIR)-controlled drug-delivery system for synergistic treatment of cancer, ultimately

  15. Ceramic fiber reinforced filter

    DOEpatents

    Stinton, David P.; McLaughlin, Jerry C.; Lowden, Richard A.

    1991-01-01

    A filter for removing particulate matter from high temperature flowing fluids, and in particular gases, that is reinforced with ceramic fibers. The filter has a ceramic base fiber material in the form of a fabric, felt, paper of the like, with the refractory fibers thereof coated with a thin layer of a protective and bonding refractory applied by chemical vapor deposition techniques. This coating causes each fiber to be physically joined to adjoining fibers so as to prevent movement of the fibers during use and to increase the strength and toughness of the composite filter. Further, the coating can be selected to minimize any reactions between the constituents of the fluids and the fibers. A description is given of the formation of a composite filter using a felt preform of commercial silicon carbide fibers together with the coating of these fibers with pure silicon carbide. Filter efficiency approaching 100% has been demonstrated with these filters. The fiber base material is alternately made from aluminosilicate fibers, zirconia fibers and alumina fibers. Coating with Al.sub.2 O.sub.3 is also described. Advanced configurations for the composite filter are suggested.

  16. Fiber optics in adverse environments

    SciTech Connect

    Lyous, P.B.

    1982-01-01

    Radiation effects in optical fibers are considered, taking into account recent progress in the investigation of radiation resistant optical fibers, radiation damage in optical fibers, radiation-induced transient absorption in optical fibers, X-ray-induced transient attenuation at low temperatures in polymer clad silica (PCS) fibers, optical fiber composition and radiation hardness, the response of irradiated optical waveguides at low temperatures, and the effect of ionizing radiation on fiber-optic waveguides. Other topics explored are related to environmental effects on components of fiber optic systems, and radiation detection systems using optical fibers. Fiber optic systems in adverse environments are also discussed, giving attention to the survivability of Army fiber optics systems, space application of fiber optics systems, fiber optic wavelength multiplexing for civil aviation applications, a new fiber optic data bus topology, fiber optics for aircraft engine/inlet control, and application of fiber optics in high voltage substations.

  17. Ice crystallization in ultrafine water-salt aerosols: nucleation, ice-solution equilibrium, and internal structure.

    PubMed

    Hudait, Arpa; Molinero, Valeria

    2014-06-01

    Atmospheric aerosols have a strong influence on Earth's climate. Elucidating the physical state and internal structure of atmospheric aqueous aerosols is essential to predict their gas and water uptake, and the locus and rate of atmospherically important heterogeneous reactions. Ultrafine aerosols with sizes between 3 and 15 nm have been detected in large numbers in the troposphere and tropopause. Nanoscopic aerosols arising from bubble bursting of natural and artificial seawater have been identified in laboratory and field experiments. The internal structure and phase state of these aerosols, however, cannot yet be determined in experiments. Here we use molecular simulations to investigate the phase behavior and internal structure of liquid, vitrified, and crystallized water-salt ultrafine aerosols with radii from 2.5 to 9.5 nm and with up to 10% moles of ions. We find that both ice crystallization and vitrification of the nanodroplets lead to demixing of pure water from the solutions. Vitrification of aqueous nanodroplets yields nanodomains of pure low-density amorphous ice in coexistence with vitrified solute rich aqueous glass. The melting temperature of ice in the aerosols decreases monotonically with an increase of solute fraction and decrease of radius. The simulations reveal that nucleation of ice occurs homogeneously at the subsurface of the water-salt nanoparticles. Subsequent ice growth yields phase-segregated, internally mixed, aerosols with two phases in equilibrium: a concentrated water-salt amorphous mixture and a spherical cap-like ice nanophase. The surface of the crystallized aerosols is heterogeneous, with ice and solution exposed to the vapor. Free energy calculations indicate that as the concentration of salt in the particles, the advance of the crystallization, or the size of the particles increase, the stability of the spherical cap structure increases with respect to the alternative structure in which a core of ice is fully surrounded by

  18. Fiber optic chemical sensors

    NASA Astrophysics Data System (ADS)

    Jung, Chuck C.; McCrae, David A.; Saaski, Elric W.

    1998-09-01

    This paper provides a broad overview of the field of fiber optic chemical sensors. Several different types of fiber optic sensors and probes are described, and references are cited for each category discussed.

  19. Soluble vs. insoluble fiber

    MedlinePlus

    ... soluble and insoluble. Both are important for health, digestion, and preventing diseases. Soluble fiber attracts water and turns to gel during digestion. This slows digestion. Soluble fiber is found in ...

  20. Omnidirectional fiber optic tiltmeter

    DOEpatents

    Benjamin, B.C.; Miller, H.M.

    1983-06-30

    A tiltmeter is provided which is useful in detecting very small movements such as earth tides. The device comprises a single optical fiber, and an associated weight affixed thereto, suspended from a support to form a pendulum. A light source, e.g., a light emitting diode, mounted on the support transmits light through the optical fiber to a group of further optical fibers located adjacent to but spaced from the free end of the single optical fiber so that displacement of the single optical fiber with respect to the group will result in a change in the amount of light received by the individual optical fibers of the group. Photodetectors individually connectd to the fibers produce corresponding electrical outputs which are differentially compared and processed to produce a resultant continuous analog output representative of the amount and direction of displacement of the single optical fiber.