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Sample records for filled high-density polyethylene

  1. Determination of Thermal Properties and Morphology of Eucalyptus Wood Residue Filled High Density Polyethylene Composites

    PubMed Central

    Mengeloglu, Fatih; Kabakci, Ayse

    2008-01-01

    Thermal behaviors of eucalyptus wood residue (EWR) filled recycled high density polyethylene (HDPE) composites have been measured applying the thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). Morphology of the materials was also studied using scanning electron microscope (SEM). Addition of the EWR into the recycled HDPE matrix reduced the starting of degradation temperature. EWR filled recycled HDPE had two main decomposition peaks, one for EWR around 350 °C and one for recycled HDPE around 460 °C. Addition of EWR did not affect the melting temperature of the recycled HDPE. Morphological study showed that addition of coupling agent improved the compatibility between wood residue and recycled HDPE. PMID:19325736

  2. Thermal properties of silica-filled high density polyethylene composites compatibilized with glut palmitate

    NASA Astrophysics Data System (ADS)

    Samsudin, Dalina; Ismail, Hanafi; Othman, Nadras; Hamid, Zuratul Ain Abdul

    2017-07-01

    A study of thermal properties resulting from the utilization of Glut Palmitate (GP) on the silica filled high density polyethylene (HDPE) composites was carried out. The composites with the incorporation of GP at 0.5, 1.0, 2.0 and 3.0 phr were prepared by using an internal mixer at the temperature 180 °C and the rotor speed of 50 rpm. The thermal behaviours of the composites were then investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the crystallinity and the thermal stability of the composites increased with the incorporation of GP. The highest crystallinity contents and decomposition temperatures were observed at the 1 phr GP loading.

  3. A novel wood flour-filled composite based on microfibrillar high-density polyethylene (HDPE)/Nylon-6 blends.

    PubMed

    Liu, Hongzhi; Yao, Fei; Xu, Yanjun; Wu, Qinglin

    2010-05-01

    A novel wood flour (WF)-filled composite based on the microfibrillar high-density polyethylene (HDPE) and Nylon-6 co-blend, in which both in situ formed Nylon-6 microfibrils and WF acted as reinforcing elements, was successfully developed using a two-step extrusion method. At the 30wt.% WF loading level, WF-filled composite based on the microfibrillized HDPE/Nylon-6 blend exhibited higher strengths and moduli than the corresponding HDPE-based composite. The incorporation of WF reduced short-term creep response of HDPE matrix and the presence of Nylon-6 microfibrils further contributed to the creep reduction. Copyright 2009 Elsevier Ltd. All rights reserved.

  4. The Rheological Behaviour of Glass-Filled Low and High Density Polyethylenes

    NASA Astrophysics Data System (ADS)

    Embery, J.; Tassieri, M.; Hine, P. J.

    2008-07-01

    This study focuses on some recent experimental results on the effects of the addition of glass beads to the linear and non-linear rheology, and hence melt processability, of two commercial shear-matched polyethylenes: an LDPE which shows strong strain hardening in elongational flow and an HDPE which does not. The beads were coated with a commercial coupling agent prior to blending with an extruder. The presence of the glass particles was found to raise the complex viscosity at all frequencies, but by different amounts depending on the frequency. The increase at low frequencies was predicted satisfactorily by the empirical Kreiger-Dougherty relationship for the low density polyethylene. The low frequency crossover, between G' and G″, was found to shift to lower frequencies with the addition of the glass beads. For the HPDE composites, the shift upwards in viscosity was lower than predicted by the KD model and also the shift of the G',G″ crossover was less than for the LDPE composites. The divergent results from the filled HDPE could be due to the different effect of the coupling agent on the properties of the neighbouring polymer. Non-linear measurements, in both shear and extension, were also carried out. The non-linear shear measurements reflected the same increase in viscosity as seen in the linear measurements at small strains. At higher strains the behaviour was different. This was particularly true for the filled LDPE composites tested in elongation, where the addition of the glass beads was found to severely suppress the strain hardening. It is expected that this is due to the development of cavities around the glass beads at higher strains, which we have seen in similar experiments on coupled glass beads in polystyrene.

  5. Kinetics of Moisture Absorption for Alkali Extracted Steam-Exploded Fiber Filled High-Density Polyethylene Composites

    NASA Astrophysics Data System (ADS)

    Taib, R. M.; Ramarad, S.; Ishak, Z. A. M.; Rozman, H. D.

    2010-03-01

    Acacia mangium wood fiber derived from steam-explosion and fiber fractionation treatment was used as fillers for high-density polyethylene (HDPE). The alkali extracted steam-exploded fibers (AEF) obtained were acetylated to produce acetylated fibers (AAEF) having three different weight percent gain (WPG). Composites of AEF or AAEF and HDPE were prepared via 2-roll mill, compression molded and cut into dumbbell specimens. All samples were immersed in water at room temperature for 30 days. The process of absorption of water by all composites followed the kinetics and mechanisms described by the Fick's theory. Diffusion coefficient (D) values increased with filler loading but decreased with increasing WPG of the AAEF fiber. Further decrease was observed when maleated polyethylene (MAPE) was added to the composite system. This was due to improved fiber-matrix adhesion that restricts movement of water molecules from further penetrate inside the composite structures.

  6. Kinetics of Moisture Absorption for Alkali Extracted Steam-Exploded Fiber Filled High-Density Polyethylene Composites

    SciTech Connect

    Taib, R. M.; Ramarad, S.; Ishak, Z. A. M.; Rozman, H. D.

    2010-03-11

    Acacia mangium wood fiber derived from steam-explosion and fiber fractionation treatment was used as fillers for high-density polyethylene (HDPE). The alkali extracted steam-exploded fibers (AEF) obtained were acetylated to produce acetylated fibers (AAEF) having three different weight percent gain (WPG). Composites of AEF or AAEF and HDPE were prepared via 2-roll mill, compression molded and cut into dumbbell specimens. All samples were immersed in water at room temperature for 30 days. The process of absorption of water by all composites followed the kinetics and mechanisms described by the Fick's theory. Diffusion coefficient (D) values increased with filler loading but decreased with increasing WPG of the AAEF fiber. Further decrease was observed when maleated polyethylene (MAPE) was added to the composite system. This was due to improved fiber-matrix adhesion that restricts movement of water molecules from further penetrate inside the composite structures.

  7. Preparation and Properties of a Novel Microcrystalline Cellulose-Filled Composites Based on Polyamide 6/High-Density Polyethylene

    PubMed Central

    Xu, Shihua; Yi, Shunmin; He, Jun; Wang, Haigang; Fang, Yiqun; Wang, Qingwen

    2017-01-01

    In the present study, lithium chloride (LiCl) was utilized as a modifier to reduce the melting point of polyamide 6 (PA6), and then 15 wt % microcrystalline cellulose (MCC) was compounded with low melting point PA6/high-density polyethylene (HDPE) by hot pressing. Crystallization analysis revealed that as little as 3 wt % LiCl transformed the crystallographic forms of PA6 from semi-crystalline to an amorphous state (melting point: 220 °C to none), which sharply reduced the processing temperature of the composites. LiCl improved the mechanical properties of the composites, as evidenced by the fact that the impact strength of the composites was increased by 90%. HDPE increased the impact strength of PA6/MCC composites. In addition, morphological analysis revealed that incorporation of LiCl and maleic anhydride grafted high-density polyethylene (MAPE) improved the interfacial adhesion. LiCl increased the glass transition temperature of the composites (the maximum is 72.6 °C). PMID:28773169

  8. Electrical resistivity of carbon black-filled high-density polyethylene (HDPE) composite containing radiation crosslinked HDPE particles

    NASA Astrophysics Data System (ADS)

    Lee, Myong-Goo; Nho, Young Chang

    2001-04-01

    The room-temperature volume resistivity of high-density polyethylene (HDPE)-carbon black (CB) blends containing previously radiation crosslinked HDPE powder was studied. The results showed that the room-temperature volume resistivity decreases with increasing concentration of crosslinked HDPE powder. It is considered that the crosslinked HDPE particles act as a filler that increases the CB volume fraction in the HDPE matrix. The results of an optical microscope observation indicated that the crosslinked polymer particles are dispersed in the HDPE/CB composite. This effect of the crosslinked particles is attributed to the fact that the crosslinked mesh size of the HDPE particles is so small that the CB particles cannot go inside them. The effect of 60Co γ-ray and electron beam (EB) irradiation on the positive temperature coefficient, negative temperature coefficient and electrical resistivity behavior of the blends were studied.

  9. A Comparative Study on AC Conductivity and Dielectric Behavior of Multiwalled Carbon Nanotubes and Polyaniline Coated Multiwalled Carbon Nanotubes Filled High Density Polyethylene-Carbon Black Nanocomposites

    SciTech Connect

    Dinesh, P.; Renukappa, N. M.; Siddaramaiah; Lee, J. H.; Jeevananda, T.

    2010-10-04

    This paper presents an experimental investigation on AC conductivity and dielectric behavior of carbon black reinforced high density polyethylene (HDPE-CB) and HDPE-CB filled with multiwalled carbon nanotubes (MWNTs-CB-HDPE) and Polyaniline (PAni) coated MWNTs-CB-HDPE nanocomposites. The electrical properties such as dielectric constant ({epsilon}'), dissipation factor (tan {delta}) and AC conductivity ({sigma}{sub ac}) of nanocomposites have been measured with reference to the weight fraction (0.5 and 1 wt% MWNTs), frequency (75 KHz-30 MHz), temperature (25-90 deg. C) and sea water ageing. The experimental results showed that the increased AC conductivity and dielectric constant of the nanocomposites were influenced by PAni coated MWNTs in HDPE-CB nanocomposites. The value of dielectric constant and tan {delta} decreased with increasing frequency. Further more, above 5 MHz the AC conductivity increases drastically whereas significant effect on tan {delta} was observed in less than 1 MHz.

  10. Improvements in processing characteristics and engineering properties of wood flour-filled high density polyethylene composite sheeting in the presence of hollow glass microspheres

    Treesearch

    Baris Yalcin; Steve E Amos; Andrew S D Souza; Craig M Clemons; I Sedat Gunes; Troy K Ista

    2012-01-01

    Hollow glass microspheres were introduced into wood flour/high density polyethylene composites by melt compounding in a twin-screw extruder. The prepared composites were subsequently converted to extruded profiles in order to obtain composite sheeting. The presence of hollow glass microspheres highly reduced the density of the extruded sheets down to 0.9 g/cc, while...

  11. Vacuum Outgassing of High Density Polyethylene

    SciTech Connect

    Dinh, L N; Sze, J; Schildbach, M A; Chinn, S C; Maxwell, R S; Raboin, P; McLean II, W

    2008-08-11

    A combination of thermogravimetric analysis (TGA) and temperature programmed decomposition (TPD) was employed to identify the outgassing species, the total amount of outgassing, and the outgassing kinetics of high density polyethylene (HDPE) in a vacuum environment. The isoconversional kinetic analysis was then used to analyze the outgassing kinetics and to predict the long-term outgassing of HDPE in vacuum applications at ambient temperature. H{sub 2}O and C{sub n}H{sub x} with n as high as 9 and x centering around 2n are the major outgassing species from solid HDPE, but the quantities evolved can be significantly reduced by vacuum baking at 368 K for a few hours prior to device assembly.

  12. Recycling of irradiated high-density polyethylene

    NASA Astrophysics Data System (ADS)

    Navratil, J.; Manas, M.; Mizera, A.; Bednarik, M.; Stanek, M.; Danek, M.

    2015-01-01

    Radiation crosslinking of high-density polyethylene (HDPE) is a well-recognized modification of improving basic material characteristics. This research paper deals with the utilization of electron beam irradiated HDPE (HDPEx) after the end of its lifetime. Powder of recycled HDPEx (irradiation dose 165 kGy) was used as a filler into powder of virgin low-density polyethylene (LDPE) in concentrations ranging from 10% to 60%. The effect of the filler on processability and mechanical behavior of the resulting mixtures was investigated. The results indicate that the processability, as well as mechanical behavior, highly depends on the amount of the filler. Melt flow index dropped from 13.7 to 0.8 g/10 min comparing the lowest and the highest concentration; however, the higher shear rate the lower difference between each concentration. Toughness and hardness, on the other hand, grew with increasing addition of the recycled HDPEx. Elastic modulus increased from 254 to 450 MPa and material hardness increased from 53 to 59 ShD. These results indicate resolving the problem of further recycling of irradiated polymer materials while taking advantage of the improved mechanical properties.

  13. Morphology of Highly Textured HDPE (High Density Polyethylene)

    DTIC Science & Technology

    1989-05-29

    Abstract -High density polyethylene ( HDPE ) specimens were subjected to high orientation producing deformations below the melting point using either a...large strain plastic flow in semi- crystalline polymers, polyethylene , texture evolution. 19 ABSTRACT (Continue on reverse if necessary and identify...high density polyethylene supplied by the USI chemical company. Its molecular weight was M. - 55,000, with a poly- dispersity ratio M.,/M, of 4.8. The

  14. Accelerated weathering of natural fiber-filled polyethylene composites

    Treesearch

    Thomas Lundin; Steven M. Cramer; Robert H. Falk; Colin. Felton

    2004-01-01

    The resistance of natural fiber-filled high-density polyethylene composite specimens to ultraviolet- (UV) and moisture-induced degradation was evaluated by measuring changes to flexural properties. High-density polyethylene (HDPE) served as the polymer matrix for four formulations: two formulations without fiber filler and two formulations one containing wood flour and...

  15. Impact fracture toughness evaluation for high-density polyethylene materials

    NASA Astrophysics Data System (ADS)

    Cherief, M. N. D.; Elmeguenni, M.; Benguediab, M.

    2017-03-01

    The impact fracture behavior of a high-density polyethylene (HDPE) material is investigated experimentally and theoretically. Single-edge notched bending (SENB) specimens are tested in experiments with three-point bending and in the Charpy impact tests. An energy model is proposed for evaluating the HDPE impact toughness, which provides a description of both brittle and ductile fracture.

  16. Effect of weathering variables on the lightness of high-density polyethylene woodflour composites

    Treesearch

    Nicole M. Stark

    2005-01-01

    Wood-plastic lumber is promoted as a low-maintenance, high-durability product. After weathering, however, wood-plastic composites (WPCs) often fade. In the first part of this study, 50 percent woodflour-filled high- density polyethylene (HDPE) composite samples were manufactured. Composites were exposed to two accelerated weathering cycles in a xenon- arc type...

  17. Radiation resistance testing of high-density polyethylene. [Gamma rays

    SciTech Connect

    Dougherty, D.R.; Adams, J.W.

    1983-01-01

    Mechanical tests following gamma inrradiation and creep tests during irradiation have been conducted on high-density polyethylene (HDPE) to assess the adequacy of this material for use in high-integrity containers (HICs). These tests were motivated by experience in nuclear power plants in which polyethylene electrical insulation detoriorated more rapidly than expected due to radiation-induced oxidation. This suggested that HDPE HICs used for radwaste disposal might degrade more rapidly than would be expected in the absence of the radiation field. Two types of HDPE, a highly cross-linked rotationally molded material and a non-cross-linked blow molded material, were used in these tests. Gamma-ray irradiations were performed at several dose rates in environments of air, Barnwell and Hanford backfill soils, and ion-exchange resins. The results of tensile and bend testing on these materials following irradiation will be presented along with preliminary results on creep during irradiation.

  18. Catalytic degradation of high density polyethylene using zeolites.

    PubMed

    Zaggout, F R; al Mughari, A R; Garforth, A

    2001-01-01

    Plastic wastes, which cause a serious environmental problem in urban areas, can serve as sources of energy. Catalytic treatment of High Density Polyethylene (HDPE) has shown that the degradation of HDPE resulted in the production of a stream of gaseous hydrocarbons varied in the range C1-C8. The degradation was carried out using diluted forms of zeolites ZSM-5, USY and Mordenite (MORD) using a fluidized bed reactor (FBR). Effect of coke formation on the activity of the catalysts was screened by thermogravimetric (TGA). ZSM-5 showed a significant resistance to deactivation because of the nature of its small pore size compared with USY and MORD.

  19. The alterations in high density polyethylene properties with gamma irradiation

    NASA Astrophysics Data System (ADS)

    Zaki, M. F.; Elshaer, Y. H.; Taha, Doaa. H.

    2017-10-01

    In the present investigation, high density polyethylene (HDPE) polymer has been used to study the alterations in its properties under gamma-irradiation. Physico-chemical properties have been investigated with different spectroscopy techniques, Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), biocompatibility properties, as well as, mechanical properties change. The FT-IR analysis shows the formation of new band at 1716 cm-1 that is attributed to the oxidation of irradiated polymer chains, which is due to the formation of carbonyl groups (C˭O). XRD patterns show that a decrease in the crystallite size and increase in the Full Width at Half Maximum (FWHM). This means that the crystallinity of irradiated samples is decreased with increase in gamma dose. The contact angle measurements show an increase in the surface free energy as the gamma irradiation increases. The measurements of mechanical properties of irradiated HDPE samples were discussed.

  20. Scoping study. High density polyethylene (HDPE) in salstone service

    SciTech Connect

    Phifer, Mark A.

    2005-02-18

    An evaluation of the use of high density polyethylene (HDPE) geomembranes in Saltstone service has been conducted due to the potential benefits that could be derived from such usage. HDPE is one of the simplest hydrocarbon polymers and one of the most common polymers utilized in the production of geomembranes, which means that its costs are relatively low. Additionally, HDPE geomembranes have an extremely low permeability and an extremely low water vapor diffusional flux, which means that it is a good barrier to contaminant transport. The primary consideration in association with HDPE geomembranes in Saltstone service is the potential impact of Saltstone on the degradation of the HDPE geomembranes. Therefore, the evaluation documented herein has primarily focused upon the potential HDPE degradation in Saltstone service.

  1. WEAR BEHAVIOR OF CARBON NANOTUBE/HIGH DENSITY POLYETHYLENE COMPOSITES

    PubMed Central

    Johnson, Brian B.; Novotny, John E.; Advani, Suresh G.

    2009-01-01

    Carbon Nanotube/High Density Polyethylene (CNT/HDPE) composites were manufactured and tested to determine their wear behavior. The nanocomposites were made from untreated multi-walled carbon nanotubes and HDPE pellets. Thin films of the precursor materials were created with varying weight percentages of nanotubes (1%, 3%, and 5%), through a process of mixing and extruding. The precursor composites were then molded and machined to create test specimens for mechanical and wear tests. These included small punch testing to compare stiffness, maximum load and work-to-failure and block-on-ring testing to determine wear behavior. Each of the tests was conducted for the different weight percentages of composite as well as pure HDPE as the baseline. The measured mechanical properties and wear resistance of the composite materials increased with increasing nanotube content in the range studied. PMID:20161101

  2. Analyzing and improving viscoelastic properties of high density polyethylene

    NASA Astrophysics Data System (ADS)

    Ahmed, Reaj Uddin

    2011-12-01

    High Density Polyethylene (HDPE) is closely packed, less branched polyethylene having higher mechanical properties, chemical resistance, and heat resistance than Low Density Polyentylene (LDPE). Better properties and cost effectiveness make it an important raw material over LDPE in packaging industries. Stacked containers made of HDPE experience static loading and deformation strain during their storage period in a warehouse. As HDPE is a viscoelastic material, dimensional stability of stacked HDPE containers depends on time dependent properties such as creep and stress relaxation. Now, light weighting is a driving force in packaging industries, which results in lower production costs but performance of the product becomes a challenge. Proper understanding of the viscoelastic properties of HDPE, with relevant FE simulation can facilitate improved designs. This research involves understanding and improving viscoelastic properties, creep behavior, and stress relaxation of HDPE. Different approaches were carried out to meet the objectives. Organic filler CaCO3 was added to HDPE at increasing weight fractions and corresponding property changes were investigated. Annealing heat treatments were also carried out for potential property improvements. The effect of ageing was also investigated on both annealed and non annealed HDPE. The related performance of different water bottles against squeeze pressure was also characterized. Both approaches, incorporation of CaCO3 and annealing, showed improvements in the properties of HDPE over neat HDPE. This research aids finding the optimum solution for improving viscoelastic properties, stress relaxation, and creep behavior of HDPE in manufacturing.

  3. Laboratory tests on fungal resistance of wood filled polyethylene composites

    Treesearch

    Craig M. Clemons; Rebecca E. Ibach

    2002-01-01

    A standard method for determining the durability of structural wood was modified for testing the fungal resistance of composites made from high density polyethylene filled with 50% wood flour. Moisture content, mechanical properties, and weight loss were measured over 12 weeks exposure to brown-and white-rot fungi. Mechanical properties were decreased, but irreversible...

  4. Gas permeation through a high density polyethylene microwave window

    SciTech Connect

    Viet Nguyen-Tuong

    1993-07-01

    Due to its low dielectric constant and low loss tangent, high density polyethylene (HDPE) has been selected for use as a high power microwave vacuum window in the Continuous Electron Beam Accelerator Facility cryounit. This window isolates the cryounit waveguide vacuum from the dry air in the external waveguide system. Gas permeation through the window will lead to cryopumping of the gas onto the cold waveguide walls and the cold ceramic window of the superconducting cavity. The gas load from permeation and outgassing of the window have to be minimized, due to the possibility of arcing when high power is applied through the waveguide. The outgassing and permeation of air through the 3.2 mm thick HDPE window were measured using the throughput method. A typical outgassing rate of 5.0 x 10{sup -1} Torr l/s/cm{sup 2} for samples baked out at 70 C was observed 20 h after pump down and bakeout. The gas load due to permeation through 34 cm{sup 2} of the window was 1.6 x 10 {sup -7} Torr l/s. The gas permeation through the 3.2 mm thick HDPE coated with a 300 nm barrier layer of SiO{sub x} was also investigated. No improvement was observed. It was presumably due to the presence of defects in the deposited SiO{sub x} layer.

  5. Fracture behavior of kaolin-reinforced high density polyethylene

    SciTech Connect

    Wetherhold, R.C.; Mouzakis, D.E.

    1999-10-01

    The addition of the low-cost mineral filler kaolin to high-density polyethylene (HDPE) creates a composite with both improved stiffness and toughness properties. This study focuses on two aspects of the toughness of these composites: the fracture toughness increment produced by work at the fracture surface and the directionality induced by the injection molding fabrication process. The Essential Work of Fracture (EWF) method gives results which show that a higher volume fraction of kaolin produces more surface work, consistent with earlier work using Compact Tension (CT) tests. The EWF method also demonstrates that a lower volume fraction can produce a higher overall plastic work and apparent toughness. A heat treatment that removes the orientation of the matrix but not that of the particles was applied to study the effect of matrix crystallinity. The results indicate that the matrix supramolecular structure (crystallinity and skin-core effect) is responsible for the directionality of toughness, and that a heat treatment can be used to produce high toughness behavior in both major directions.

  6. Calvarial reconstruction using high-density porous polyethylene cranial hemispheres

    PubMed Central

    Mokal, Nitin J.; Desai, Mahinoor F.

    2011-01-01

    Aims: Cranial vault reconstruction can be performed with a variety of autologous or alloplastic materials. We describe our experience using high-density porous polyethylene (HDPE) cranial hemisphere for cosmetic and functional restoration of skull defects. The porous nature of the implant allows soft tissue ingrowth, which decreases the incidence of infection. Hence, it can be used in proximity to paranasal sinuses and where previous alloplastic cranioplasties have failed due to implant infection. Materials and Methods: We used the HDPE implant in seven patients over a three-year period for reconstruction of moderate to large cranial defects. Two patients had composite defects, which required additional soft tissue in the form of free flap and tissue expansion. Results: In our series, decompressive craniectomy following trauma was the commonest aetiology and all defects were located in the fronto-parieto-temporal region. The defect size was 10 cm on average in the largest diameter. All patients had good post-operative cranial contour and we encountered no infections, implant exposure or implant migration. Conclusions: Our results indicate that the biocompatibility and flexibility of the HDPE cranial hemisphere implant make it an excellent alternative to existing methods of calvarial reconstruction. PMID:22279274

  7. Fibrovascularization and osteogenesis in high-density porous polyethylene implants.

    PubMed

    Oliveira, Renato Victor; de Souza Nunes, Leandro Soeiro; Filho, Hugo Nary; de Andrade Holgado, Leandro; Ribeiro, Daniel Araki; Matsumoto, Mariza Akemi

    2009-07-01

    High-density porous polyethylene (HDPP) has been extensively used in craniofacial reconstructions with high-level success and minimal complications. It is known for its biocompatibility and satisfactory stability in the receptor bone area, presenting only a few reports of mobility and infection. In the current study, attention was given to the interface area between HDPP and bone surface to analyze fibrous and bone tissue formation and ingrowth into the pores of the material placed in the mandible of rabbits. Twelve male New Zealand rabbits underwent surgical procedure to receive bilateral HDPP implants in buccal face of dentate mandibular alveolar process, fixed with titanium screws. After 7, 14, 45, and 90 days, the animals were killed, and the specimens were retrieved for histologic and immunohistochemical analyses. No implant loss or infection was detected at the retrieval of the specimens. The microscopic analysis presented satisfactory integration of the material to the bone surface, with new bone formation from the receptor bed and inside the pores of the material, observed from the 15th day. After 90 days, remodeling bone and fibrous tissue was seen in the interface region. Among some of the pores, mature lamellar bone was present. Immunohistochemistry pointed out a moderate expression either to Core binding factor protein 1/RUNX2 or to vascular endothelial growth factor for early periods evaluated, that is, 7 and 15 days after surgery. These results confirm the osteoconductive behavior and high biocompatibility of the material, associated to its adequate immobilization, leading to its lifelong presence in human biologic system.

  8. Crystallization Studies of Blends of Low Density Polyethylene and High Density Polyethylene

    NASA Astrophysics Data System (ADS)

    Puig, C.; Gomez, S.; Castañeda, R.

    1997-03-01

    The incorporation of low density polyethylene (LDPE) segments within the high density polyethylene (HDPE) lamellae on cooling from the molten state is investigated using differential scanning calorimetry. Rich LDPE blends (>80%) on quenching from the melt exhibited partial cocrystallization. Two endotherms on heating are observed, the LDPE is the main component of the low melting endotherm whereas the HDPE is the main component of the high melting endotherm. A depression in the high melting temperature peak is observed. In addition, on subsequent treatment the crystallization behaviour under controlled conditions of the low melting component in quenched blends is studied and it shows a shift in the crystallization temperature when compared with pure LDPE. After reheating a depression in the low melting temperature with increasing HDPE content in the blend is observed. The effect of cooling conditions used from the melt on the cocrystallization between the two polymers is studied.

  9. LLCE burial container high density polyethylene chemical compatibility

    SciTech Connect

    Veith, E.M., Westinghouse Hanford

    1996-08-20

    An independent chemical compatibility review of LLCE HDPE polyethylene burial containers was conducted to evaluate the container resistance to the chemicals and constituents thought to reside within the Tank Farms. The study concluded that the LLCE Burial Container fabricated from HDPE Polyethylene was a good choice for this application. The reviewer was unaware that the specification for these containers require 2 - 3 percent finely dispensed carbon black which allows long term storage outside.

  10. High Density Polyethylene Composites Reinforced with Hybrid Inorganic Fillers: Morphology, Mechanical and Thermal Expansion Performance

    PubMed Central

    Huang, Runzhou; Xu, Xinwu; Lee, Sunyoung; Zhang, Yang; Kim, Birm-June; Wu, Qinglin

    2013-01-01

    The effect of individual and combined talc and glass fibers (GFs) on mechanical and thermal expansion performance of the filled high density polyethylene (HDPE) composites was studied. Several published models were adapted to fit the measured tensile modulus and strength of various composite systems. It was shown that the use of silane-modified GFs had a much larger effect in improving mechanical properties and in reducing linear coefficient of thermal expansion (LCTE) values of filled composites, compared with the use of un-modified talc particles due to enhanced bonding to the matrix, larger aspect ratio, and fiber alignment for GFs. Mechanical properties and LCTE values of composites with combined talc and GF fillers varied with talc and GF ratio at a given total filler loading level. The use of a larger portion of GFs in the mix can lead to better composite performance, while the use of talc can help lower the composite costs and increase its recyclability. The use of 30 wt % combined filler seems necessary to control LCTE values of filled HDPE in the data value range generally reported for commercial wood plastic composites. Tensile modulus for talc-filled composite can be predicted with rule of mixture, while a PPA-based model can be used to predict the modulus and strength of GF-filled composites. PMID:28788322

  11. Measurements and predictions of outgassing from high density polyethylene (HDPE), PBX9502, and certain silicones by the isoconversional analysis

    SciTech Connect

    Dinh, L N; Glascoe, E A; Schildbach, M A; Chinn, S C; Maxwell, R S; McLean II, W

    2009-07-06

    The techniques of mass spectrometry and temperature programmed decomposition were used to measure outgassing kinetics from high density polyethylene, insensitive high explosive PBX 9502, and silica-filled polysiloxane TR55 and S5370. The isoconversional thermal analysis method was then employed to extract outgassing kinetics and to make kinetic predictions for long term outgassing at lower temperatures. The accuracy, advantages and disadvantages of the isoconversional analysis in terms of kinetic prediction for these materials and some others will be discussed.

  12. Mechanical and thermal properties of high density polyethylene – dried distillers grains with solubles composites

    USDA-ARS?s Scientific Manuscript database

    Dried Distillers Grain with Solubles (DDGS) is evaluated as a bio-based fiber reinforcement. Injection molded composites of high density polyethylene (HDPE), 25% by weight of DDGS, and either 5% of 0% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding and injection mo...

  13. Properties of high density polyethylene – Paulownia wood flour composites via injection molding

    USDA-ARS?s Scientific Manuscript database

    Paulownia wood (PW) flour is evaluated as a bio-based fiber reinforcement. Composites of high density polyethylene (HDPE), 25% by weight of PW, and either 0% or 5% by weight of maleated polyethylene (MAPE) were produced by twin screw compounding followed by injection molding. Molded test composite...

  14. Plasma modification of sisal and high-density polyethylene composites : effect on mechanical properties

    Treesearch

    A.R. Martin; S. Manolache; L.H.C. Mattoso; R.M. Rowell; F. Denes

    2000-01-01

    Sisal fibers and finely powdered high-density polyethylene were surface functionalized using dichlorosilane (DS) under R-F plasma conditions to improve interfacial adhesion between the two dissimilar substrates. The functionalized polyethylene (70%) and sisal (30%) were compounded on four different ways using thermokinetic mixer and injected molded into composites...

  15. An investigation on chloroprene-compatibilized acrylonitrile butadiene rubber/high density polyethylene blends

    PubMed Central

    Ahmed, Khalil

    2014-01-01

    Blends of acrylonitrile butadiene rubber/high density polyethylene (NBR/HDPE) compatibilized by Chloroprene rubber (CR) were prepared. A fixed quantity of industrial waste such as marble waste (MW, 40 phr) was also included. The effect of the blend ratio and CR on cure characteristics, mechanical and swelling properties of MW-filled NBR/HDPE blends was investigated. The results showed that the MW-filled NBR/HDPE blends revealed an increase in tensile strength, tear, modulus, hardness and cross-link density for increasing weight ratio of HDPE. The minimum torque (ML) and maximum torque (MH) of blends increased with increasing weight ratio of HDPE while scorch time (ts2) cure time (tc90), compression set and abrasion loss of blends decreased with increasing weight ratio of HDPE. The blends also showed a continuous reduction in elongation at break as well as swelling coefficient with increasing HDPE amount in blends. MW filled blends based on CR provided the most encouraging balance values of overall properties. PMID:26644917

  16. An investigation on chloroprene-compatibilized acrylonitrile butadiene rubber/high density polyethylene blends.

    PubMed

    Ahmed, Khalil

    2015-11-01

    Blends of acrylonitrile butadiene rubber/high density polyethylene (NBR/HDPE) compatibilized by Chloroprene rubber (CR) were prepared. A fixed quantity of industrial waste such as marble waste (MW, 40 phr) was also included. The effect of the blend ratio and CR on cure characteristics, mechanical and swelling properties of MW-filled NBR/HDPE blends was investigated. The results showed that the MW-filled NBR/HDPE blends revealed an increase in tensile strength, tear, modulus, hardness and cross-link density for increasing weight ratio of HDPE. The minimum torque (M L) and maximum torque (M H) of blends increased with increasing weight ratio of HDPE while scorch time (ts2) cure time (tc90), compression set and abrasion loss of blends decreased with increasing weight ratio of HDPE. The blends also showed a continuous reduction in elongation at break as well as swelling coefficient with increasing HDPE amount in blends. MW filled blends based on CR provided the most encouraging balance values of overall properties.

  17. High-density polyethylene (HDPE) faces slower growth

    SciTech Connect

    Savage, R.

    1980-05-19

    According to R. Savage of American Hoechst Corp., the 1979 U.S. HDPE capacity, production, plant operating rate, domestic shipments, and total shipments are (in millions of lb) 5400, 5010, 93%, 4284, and 4893, respectively. For 1984, the corresponding figures are 8800, 7300, 83%, 6500, and 7150. HDPE is entering the 'mature' phase of its cycle, and will not, in the future, be able to match the 13.3%/yr avg growth rate for the last five years, but the increase in capacity this year to 6 billion lb and the predicted 7.9%/yr avg increase through 1984, indicate that HDPE will outperform much of its competition. Plant operating rates were high last year because some HDPE capacity was converted to low-density polyethylene capacity. The HDPE export market will remain flat through 1984 because other countries are increasing capacity and the U.S. price advantage will disappear. HDPE capacity additions planned by U.S. companies, and HDPE uses, particularly blow-molding and injecting molding applications (the major uses of HDPE), are discussed.

  18. The application and progress of high-density porous polyethylene in the repair of orbital wall defect.

    PubMed

    Qian, Zhuyun; Fan, Xianqun

    2014-07-01

    High-density porous polyethylene is a type of polymeric biomaterial. When used to efficiently fill the extensive orbital volume and correct enophthalmos caused by orbital wall defect, it has a significant advantage of biocompatibility, which results in a low rate of postoperative exposure and infection. The major disadvantage of this material is its radiolucency. However, with the development of imaging techniques, it is now possible to use multidetector computed tomography to directly contour the implant and describe its position. The use of tissue engineering involving high-density porous polyethylene will further improve its biocompatibility. At the same time, composite materials will play an important role in the repair of orbital wall defect.

  19. Mechanical properties of high density polyethylene--pennycress press cake composites

    USDA-ARS?s Scientific Manuscript database

    Pennycress press cake (PPC) is evaluated as a bio-based fiber reinforcement. PPC is a by-product of crop seed oil extraction. Composites with a high density polyethylene (HDPE) matrix are created by twin screw compounding of 25% by weight of PPC and either 0% or 5% by weight of maleated polyethyle...

  20. Catalytic and thermal depolymerization of low value post-consumer high density polyethylene plastic

    USDA-ARS?s Scientific Manuscript database

    The feasibility of catalytic and non-catalytic pyrolytic conversion of low value post-consumer high density polyethylene (HDPE) plastic into crude oil and subsequent distillation was explored. Translation of optimized conditions for catalytic and non-catalytic pyrolysis from TGA to a bench-scale sys...

  1. Evaluation of release of antioxidant from high density polyethylene by planar chromatography.

    PubMed

    Dreassi, E; Bonifacio, M; Corti, P

    1998-01-01

    Irganox 1330 (1,3,5-trimethyl-2,4,5-tris(3',5'-ditert-butyl)-4'-hydroxybenzyl)- benzene) (I), an alkylphenol compound used as antioxdiant in the production of high density polyethylene (HDPE), was the subject of this study. The quantity of I given up by polyethylene samples of different thickness to aqueous and lipophilic media simulating food was studied by planar chromatography (PC). The manner of antioxidant release was also investigated. The chromatographic method developed was found satisfactory for the quantification of I in the migration studies undertaken, and had quantification limits (12 ng/deposit) suitable for quality control of HDPE.

  2. A complete life cycle assessment of high density polyethylene plastic bottle

    NASA Astrophysics Data System (ADS)

    Treenate, P.; Limphitakphong, N.; Chavalparit, O.

    2017-07-01

    This study was aimed to determine environmental performances of a lubricant oil bottle made from high density polyethylene and to develop potential measures for reducing its impacts. A complete life cycle assessment was carried out to understand a whole effect on the environment from acquiring, processing, using, and disposing the product. Two scenarios of disposal phase; recycle and incineration: were examined to quantify a lesser degree on environmental impact. The results illustrated that major impacts of the two scenarios were at the same categories with the highest contributor of raw material acquisition and pre-processing. However, all impacts in case of recycling provided a lower point than that in case of incineration, except mineral extraction. Finally, feasible measures for reducing the environmental impact of high density polyethylene plastic bottle were proposed in accordance with 3Rs concept.

  3. Time–temperature superposition principle applied to a kenaf-fiber/high-density polyethylene composite

    Treesearch

    Mehdi Tajvidi; Robert H. Falk; John C. Hermanson

    2005-01-01

    The time–temperature superposition principle was applied to the viscoelastic properties of a kenaf- fiber/high-density polyethylene (HDPE) composite, and its validity was tested. With a composite of 50% kenaf fibers, 48% HDPE, and 2% compatibilizer, frequency scans from a dynamic mechanical analyzer were performed in the range of 0.1–10 Hz at five different...

  4. High density porous polyethylene material (Medpor) as an unwrapped orbital implant.

    PubMed

    Chen, Yan-hong; Cui, Hong-guang

    2006-08-01

    To introduce the clinical effect among patients who received an unwrapped orbital implant with high density porous polyethylene material (Medpor) after enucleation or evisceration. Retrospective analysis of a series of 302 patients with anophthalmia who underwent placement of an unwrapped high density porous polyethylene orbital implant. We compared the patients (n=180) who accepted primary implant placement with those (n=122) who accepted secondary implant placement. Parameters evaluated included: age at time of surgery, date of surgery, sex, implant type and size, surgery type, the surgical procedure and technique performed, and complications. The time of follow-up ranged from 2.0 to 58.0 months (mean 32.5 months). A total of 5 of 302 (1.66%) cases had documented postoperative complications. The following problems were noted after surgery: implant exposure, 3 patients (0.99%); implant removed due to orbital infection, 1 patient (0.34%); ptosis, 1 patient (0.34%). There were no significant complications observed in other 297 cases and all implants showed good orbital motility. The clinical effect of primary implant placement is better than that of secondary placement. High density porous polyethylene material can be used successfully as an unwrapped orbital implant in anopthalmic socket surgery with minimal complications. The material is well tolerated, nonantigenic and has low rate of infection and migration.

  5. High density porous polyethylene material (Medpor) as an unwrapped orbital implant

    PubMed Central

    Chen, Yan-hong; Cui, Hong-guang

    2006-01-01

    Objective: To introduce the clinical effect among patients who received an unwrapped orbital implant with high density porous polyethylene material (Medpor) after enucleation or evisceration. Methods: Retrospective analysis of a series of 302 patients with anophthalmia who underwent placement of an unwrapped high density porous polyethylene orbital implant. We compared the patients (n=180) who accepted primary implant placement with those (n=122) who accepted secondary implant placement. Parameters evaluated included: age at time of surgery, date of surgery, sex, implant type and size, surgery type, the surgical procedure and technique performed, and complications. Results: The time of follow-up ranged from 2.0 to 58.0 months (mean 32.5 months). A total of 5 of 302 (1.66%) cases had documented postoperative complications. The following problems were noted after surgery: implant exposure, 3 patients (0.99%); implant removed due to orbital infection, 1 patient (0.34%); ptosis, 1 patient (0.34%). There were no significant complications observed in other 297 cases and all implants showed good orbital motility. The clinical effect of primary implant placement is better than that of secondary placement. Conclusion: High density porous polyethylene material can be used successfully as an unwrapped orbital implant in anopthalmic socket surgery with minimal complications. The material is well tolerated, nonantigenic and has low rate of infection and migration. PMID:16845724

  6. Optimization of Cold Spray Deposition of High-Density Polyethylene Powders

    NASA Astrophysics Data System (ADS)

    Bush, Trenton B.; Khalkhali, Zahra; Champagne, Victor; Schmidt, David P.; Rothstein, Jonathan P.

    2017-09-01

    When a solid, ductile particle impacts a substrate at sufficient velocity, the resulting heat, pressure and plastic deformation can produce bonding between the particle and the substrate. The use of a cool supersonic gas flow to accelerate these solid particles is known as cold spray deposition. The cold spray process has been commercialized for some metallic materials, but further research is required to unlock the exciting potential material properties possible with polymeric particles. In this work, a combined computational and experimental study was employed to study the cold spray deposition of high-density polyethylene powders over a wide range of particle temperatures and impact velocities. Cold spray deposition of polyethylene powders was demonstrated across a range broad range of substrate materials including several different polymer substrates with different moduli, glass and aluminum. A material-dependent window of successful deposition was determined for each substrate as a function of particle temperature and impact velocity. Additionally, a study of deposition efficiency revealed the optimal process parameters for high-density polyethylene powder deposition which yielded a deposition efficiency close to 10% and provided insights into the physical mechanics responsible for bonding while highlighting paths toward future process improvements.

  7. Optimization of Cold Spray Deposition of High-Density Polyethylene Powders

    NASA Astrophysics Data System (ADS)

    Bush, Trenton B.; Khalkhali, Zahra; Champagne, Victor; Schmidt, David P.; Rothstein, Jonathan P.

    2017-10-01

    When a solid, ductile particle impacts a substrate at sufficient velocity, the resulting heat, pressure and plastic deformation can produce bonding between the particle and the substrate. The use of a cool supersonic gas flow to accelerate these solid particles is known as cold spray deposition. The cold spray process has been commercialized for some metallic materials, but further research is required to unlock the exciting potential material properties possible with polymeric particles. In this work, a combined computational and experimental study was employed to study the cold spray deposition of high-density polyethylene powders over a wide range of particle temperatures and impact velocities. Cold spray deposition of polyethylene powders was demonstrated across a range broad range of substrate materials including several different polymer substrates with different moduli, glass and aluminum. A material-dependent window of successful deposition was determined for each substrate as a function of particle temperature and impact velocity. Additionally, a study of deposition efficiency revealed the optimal process parameters for high-density polyethylene powder deposition which yielded a deposition efficiency close to 10% and provided insights into the physical mechanics responsible for bonding while highlighting paths toward future process improvements.

  8. The yield and post-yield behavior of high-density polyethylene

    NASA Technical Reports Server (NTRS)

    Semeliss, M. A.; Wong, R.; Tuttle, M. E.

    1990-01-01

    An experimental and analytical evaluation was made of the yield and post-yield behavior of high-density polyethylene, a semi-crystalline thermoplastic. Polyethylene was selected for study because it is very inexpensive and readily available in the form of thin-walled tubes. Thin-walled tubular specimens were subjected to axial loads and internal pressures, such that the specimens were subjected to a known biaxial loading. A constant octahederal shear stress rate was imposed during all tests. The measured yield and post-yield behavior was compared with predictions based on both isotropic and anisotropic models. Of particular interest was whether inelastic behavior was sensitive to the hydrostatic stress level. The major achievements and conclusions reached are discussed.

  9. Solving a product safety problem using a recycled high density polyethylene container

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, T. L.

    1993-01-01

    The objectives are to introduce basic problem-solving techniques for product safety including problem identification, definition, solution criteria, test process and design, and data analysis. The students are given a recycled milk jug made of high density polyethylene (HDPE) by blow molding. The objectives are to design and perform proper material test(s) so they can evaluate the product safety if the milk jug is used in a certain way which is specified in the description of the procedure for this investigation.

  10. FTIR study of the melt grafting of high density polyethylene with amino, sulfonate, and mercapto esters

    NASA Astrophysics Data System (ADS)

    Anbarasan, R.; Dhanalakshmi, V.

    2010-11-01

    High-density polyethylene (HDPE) was melt-functionalized with three different esters at 160oC in the presence of dicumyl peroxide (DCP), a free radical initiator, under nitrogen atmosphere at different % weight loadings of esters. DCP and the esters were taken for the melt functionalization reaction in 1:1 ratio. FTIR spectroscopy was used to determine the % grafting of esters onto the HDPE backbone quantitatively. Diethyl mercaptosuccinate (DEMS) produced the highest % grafting with lowest % cross-linking values, whereas anthranilic acid cinnamoyl ester (AACE) yielded the highest % cross-linking with the lowest % grafting values.

  11. Statistical modeling of crack growth and reliability assessment of high-density polyethylene

    SciTech Connect

    Qureshi, F.S.; Sheikh, A.K.; Khan, Z.; Ahmad, M.

    1999-06-01

    In this work, a statistical evaluation of the crack-growth process in high-density polyethylene (HDPE) was carried out. The specimens were compression molded from virgin, molding-grade HDPE. Edge-notched specimens for replicate fatigue testing were prepared from compression-molded sheets. Fatigue test results were then analyzed, and it is shown that if the crack-growth process can be characterized as a random process following a power-law-type behavior, then the time to reach a critical crack length will be distributed according to an inverted lognormal model.

  12. High-density polyethylene pipe: A new material for pass-by passive integrated transponder antennas

    USGS Publications Warehouse

    Kazyak, David C.; Zydlewski, Joseph

    2012-01-01

    Pass-by passive integrated transponder (PIT) antennas are widely used to study the movements of fish in streams. At many sites, stream conditions make it difficult to maintain antennas and obtain a continuous record of movement. We constructed pass-by PIT antennas by using high-density polyethylene (HDPE) and found them to be robust to high flows and winter ice flows. Costs for HDPE antennas were similar to those of traditional polyvinyl chloride (PVC) antennas, although construction was somewhat more complicated. At sites where PVC antennas are frequently damaged, HDPE is a durable and economical alternative for PIT antenna construction.

  13. Solving a product safety problem using a recycled high density polyethylene container

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, T. L.

    1993-01-01

    The objectives are to introduce basic problem-solving techniques for product safety including problem identification, definition, solution criteria, test process and design, and data analysis. The students are given a recycled milk jug made of high density polyethylene (HDPE) by blow molding. The objectives are to design and perform proper material test(s) so they can evaluate the product safety if the milk jug is used in a certain way which is specified in the description of the procedure for this investigation.

  14. Mechanical effects of high density polyethylene dynamic compression plate hole inserts on bone-plate constructs.

    PubMed

    Sullivan, E K; Nunamaker, D M; Richardson, D W

    2005-01-01

    This study was conducted in order to investigate the mechanical effects of high density polyethylene screw hole inserts in 4.5 mm Dynamic Compression Plate (DCP)--synthetic bone constructs. A mid-shaft 'osteotomy' was created in synthetic bone cylinders. The bisecting 'osteotomy' was reduced using six-hole broad DCPs and 4.5 mm cortical bone screws. The screws adjacent to the 'osteotomy' were placed using a load-guide. The remaining screws were placed in neutral position. High density polyethylene DCP screw hole inserts were incorporated with each screw in neutral position, in the experimental group. The bone plate constructs were tested in four point cyclical bending with the plates loaded at 2,000 Newtons, for a total of 6,000 cycles. Osteotomy gap was measured at 3,000 and 6,000 cycles. Screw head deflection adjacent to the osteotomy was measured. Kruskal-Wallis non-parametric testing was used for statistical comparisons. There was significantly less gapping at the osteotomy site in the treatment group after 3,000 cycles (0.49 +/- 0.18 mm [control] vs. 0.06 +/- 0.14 mm [treated], P=0.02) and 6,000 cycles (0.6 +/- 0.18 mm [control] vs. 0.1 +/- 0.22 mm [treated], P=0.02). The screws adjacent to the gap were significantly more deformed in the control group than those in the treated constructs (3.63 +/- 1.81 [control] vs. 1.06 +/- 1.55 [treated], P=0.0002). The polyethylene inserts improved the interface between bone plate and screw head, resulting in decreased relative movement of the implant and bone. The polyethylene inserts also resulted in less bending of the loaded screws.

  15. Large area neutron detector based on Li6 ionization chamber with integrated body-moderator of high density polyethylene

    SciTech Connect

    Ianakiev, Kiril D.; Swinhoe, Martyn T.; Chung, Kiwhan; Makela, Mark F.

    2009-06-30

    A detector was developed and funded by DHS to be a lower cost alternative to 3He detectors. A 6Li foil-lined ionization chamber was prepared with fill gas at one atmosphere and pulse mode operation. The high-density polyethylene (HOPE) body serves also as a neutron moderator. All electrodes, including high voltage bias supply, are hermetically sealed within the plastic slabs.

  16. Mechanical and Linear Viscoelastic Properties of High Density Polyethylene Obtained from Tensile and Dead-Load Creep Tests

    DTIC Science & Technology

    1990-06-01

    from virgin pellets. Table 1. CHEMICAL ANALYSIS OF THREE GRADES OF HIGH DENSITY POLYETHYLENE Molecular Weight Mw Mn Melt Weight Number Flow HLMI...SECURITM CLASSIFICATON OF THIS PAGE (When Data Entered) Block No. 20 ABSTRACT Three grades of high density polyethylene ( HDPE ) are tested for tensile...66 Company’s materials literature, along with melt - flow index values, are tabulated in Table I along with our values obtained from the gel per

  17. Influence of natural fibers on the phase transitions in high-density polyethylene composites using dynamic mechanical analysis

    Treesearch

    Mehdi Tajvidi; Robert H. Falk; John C. Hermanson; Colin Felton

    2003-01-01

    Dynamic mechanical analysis was employed to evaluate the performance of various natural fibers in high-density polyethylene composites. Kenaf, newsprint, rice hulls, and wood flour were sources of fiber. Composites were made at 25 percent and 50 percent by weight fiber contents. Maleic anhydride modified polyethylene was also added at 1:25 ratio to the fiber....

  18. Effect of ultraviolet radiation in the photo-oxidation of High Density Polyethylene and Biodegradable Polyethylene films

    NASA Astrophysics Data System (ADS)

    Martínez-Romo, A.; González Mota, R.; Bernal, J. J. Soto; Frausto Reyes, C.; Rosales Candelas, I.

    2015-01-01

    One of the most widely used plastics in the world is the High density polyethylene (HDPE), it is a stable material due to its carbon-carbon bonds, causing their slow degradation; which is why we are looking for alternative ways to accelerate the degradation process of this polymer. An alternative is the addition of oxidized groups in its molecular structure, which results in the development of polymers susceptible to biodegradation (PE-BIO). In this paper, HDPE and PE-BIO films were exposed to UV-B radiation (320-280 nm) at different exposure times, 0-60 days. The effects of UV radiation in samples of HDPE and PE-BIO were characterized using infrared spectroscopy with attenuated total reflectance (ATR). The results show that the exposed materials undergo changes in their molecular structure, due to the infrared bands formed which corresponds to the photo-oxidation of HDPE and PE films when submitted to UV-B radiation.

  19. Bone-resorptive effects of endotoxin-contaminated high-density polyethylene particles spontaneously eliminated in vivo.

    PubMed

    Skoglund, B; Larsson, L; Aspenberg, P A

    2002-07-01

    Wear particles commonly used for experiments may carry adherent endotoxin on their surfaces, which may be responsible for the observed effects. In this study, we attached titanium plates to the tibiae of 20 rats. After osseointegration, endotoxin-contaminated or uncontaminated high-density-polyethylene (HDPE) particles were applied. Contaminated specimens showed a dramatic resorption of bone after seven days but new bone filled the site again at 21 days. Uncontaminated specimens showed no resorption. In 18 rats we implanted intramuscularly discs of ultra-high-molecular-weight polyethylene (UHMWPE) with baseline or excess contamination of endotoxin. Excess endotoxin disappeared within 24 hours and the amount of endotoxin remained at baseline level (contamination from production). Uncontaminated titanium discs did not adsorb endotoxin in vivo. The endotoxin was measured by analytical chemistry. Locally-applied endotoxin stimulated bone resorption similarly to that in experiments with wear particles. Endotoxin on the surface of implants and particles appeared to be inactivated in situ. A clean implant surface did not adsorb endotoxin. Our results suggest that endotoxin adhering to orthopaedic implants is not a major cause for concern.

  20. Preparation of High Density Polyethylene/Waste Polyurethane Blends Compatibilized with Polyethylene-Graft-Maleic Anhydride by Radiation

    PubMed Central

    Park, Jong-Seok; Lim, Youn-Mook; Nho, Young-Chang

    2015-01-01

    Polyurethane (PU) is a very popular polymer that is used in a variety of applications due to its good mechanical, thermal, and chemical properties. However, PU recycling has received significant attention due to environmental issues. In this study, we developed a recycling method for waste PU that utilizes the radiation grafting technique. Grafting of waste PU was carried out using a radiation technique with polyethylene-graft-maleic anhydride (PE-g-MA). The PE-g-MA-grafted PU/high density polyethylene (HDPE) composite was prepared by melt-blending at various concentrations (0–10 phr) of PE-g-MA-grafted PU. The composites were characterized using fourier transform infrared spectroscopy (FT-IR), and their surface morphology and thermal/mechanical properties are reported. For 1 phr PU, the PU could be easily introduced to the HDPE during the melt processing in the blender after the radiation-induced grafting of PU with PE-g-MA. PE-g-MA was easily reacted with PU according to the increasing radiation dose and was located at the interface between the PU and the HDPE during the melt processing in the blender, which improved the interfacial interactions and the mechanical properties of the resultant composites. However, the elongation at break for a PU content >2 phr was drastically decreased. PMID:28788022

  1. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    NASA Astrophysics Data System (ADS)

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-01

    A recent low gas-fill density (0.6 mg/cc 4He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc 4He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  2. High-density carbon ablator ignition path with low-density gas-filled rugby hohlraum

    SciTech Connect

    Amendt, Peter; Ho, Darwin D.; Jones, Ogden S.

    2015-04-15

    A recent low gas-fill density (0.6 mg/cc {sup 4}He) cylindrical hohlraum experiment on the National Ignition Facility has shown high laser-coupling efficiency (>96%), reduced phenomenological laser drive corrections, and improved high-density carbon capsule implosion symmetry [Jones et al., Bull. Am. Phys. Soc. 59(15), 66 (2014)]. In this Letter, an ignition design using a large rugby-shaped hohlraum [Amendt et al., Phys. Plasmas 21, 112703 (2014)] for high energetics efficiency and symmetry control with the same low gas-fill density (0.6 mg/cc {sup 4}He) is developed as a potentially robust platform for demonstrating thermonuclear burn. The companion high-density carbon capsule for this hohlraum design is driven by an adiabat-shaped [Betti et al., Phys. Plasmas 9, 2277 (2002)] 4-shock drive profile for robust high gain (>10) 1-D ignition performance and large margin to 2-D perturbation growth.

  3. Enhancement of in vitro high-density polyethylene (HDPE) degradation by physical, chemical, and biological treatments.

    PubMed

    Balasubramanian, V; Natarajan, K; Rajeshkannan, V; Perumal, P

    2014-11-01

    Partially degraded high-density polyethylene (HDPE) was collected from plastic waste dump yard for biodegradation using fungi. Of various fungi screened, strain MF12 was found efficient in degrading HDPE by weight loss and Fourier transform infrared (FT-IR) spectrophotometric analysis. Strain MF12 was selected as efficient HDPE degraders for further studies, and their growth medium composition was optimized. Among those different media used, basal minimal medium (BMM) was suitable for the HDPE degradation by strain MF12. Strain MF12 was subjected to 28S rRNA sequence analysis and identified as Aspergillus terreus MF12. HDPE degradation was carried out using combinatorial physical and chemical treatments in conjunction to biological treatment. The high level of HDPE degradation was observed in ultraviolet (UV) and KMnO4/HCl with A. terreus MF12 treatment, i.e., FT10. The abiotic physical and chemical factors enhance the biodegradation of HDPE using A. terreus MF12.

  4. Gasification of biomass/high density polyethylene mixtures in a downdraft gasifier.

    PubMed

    García-Bacaicoa, P; Mastral, J F; Ceamanos, J; Berrueco, C; Serrano, S

    2008-09-01

    In this work, an experimental study of the thermal decomposition of mixtures of wood particles and high density polyethylene in different atmospheres has been carried out in a downdraft gasifier with a nominal processing capacity of 50 kg/h. The main objective was to study the feasibility of the operation of the gasification plant using mixtures and to investigate the characteristics of the gas obtained. In order to do so, experiments with biomass only and with mixtures with up to 15% HDPE have been carried out. The main components of the gas generated are N(2) (50%), H(2) (14%), CO (9-22%) and CO(2) (7-17%) and its relatively high calorific value was adequate for using it in an internal combustion engine generator consisting of a modified diesel engine coupled with a 25 kV A alternator.

  5. Application of schlieren interferometry to temperature measurements during laser welding of high-density polyethylene films.

    PubMed

    Coelho, João M P; Abreu, Manuel A; Rodrigues, F Carvalho

    2003-11-01

    Schlieren interferometry is found to be an alternative tool for temperature measurement during thermoplastic laser welding with regard to methods based on thermocouples or optical pyrometers. In fact, these techniques are not easily applied when materials to be processed have reduced thickness, negligible heat conduction, and low emissivity, as is the case of welding high-density polyethylene films with 10.6-microm CO2 laser radiation, even if the method reaches its applicability limit after approximately 1 s of the interaction process. The schlieren method provides the means and the results to probe the thermal variations of the laser-thermoplastic interaction on both the surface and the interface between the sample material and the air.

  6. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites

    NASA Astrophysics Data System (ADS)

    Liu, Tian; Wood, Weston; Zhong, Wei-Hong

    2011-12-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  7. A multivariate analysis of the effects of multiple extrusion cycles on high density polyethylene bottle resin

    SciTech Connect

    Zahavich, A.

    1995-10-01

    The recycling of post consumer (PCR) high density polyethylene (HDPE) blow molding resins has increased dramatically over the past 5 years. The focus of research for this product has been on specific performance and processing properties such as tensile or melt strength. Little work has been done on studying the entire range of properties as a whole, particularly in the area of multiple extrusions. This paper describes a designed experiment study where multivariate statistical techniques were used to compare 2 HDPE and 2 HDPE PCR materials, in terms of changes in a number of properties with exposure to multiple extrusions. Virgin homopolymer and copolymer resins and PCR, mixed color bottle and natural, were passed through 4 extrusion cycles. Viscosity, swell, melt strength, crystallinity, polydispersity and ESCR properties were studied using principal component analysis.

  8. Improved SEC-FTIR method for the characterization of multimodal high-density polyethylenes.

    PubMed

    Piel, Christian; Albrecht, Andreas; Neubauer, Corinna; Klampfl, Christian W; Reussner, Jens

    2011-06-01

    A size-exclusion chromatography-Fourier transform infrared spectroscopy (SEC-FTIR) method for the analysis of high-density polyethylene copolymers was developed, providing superior resolution for the determination of short-chain branching as a function of time and improved repeatability by hardware adaptation and processing optimization. SEC-FTIR for characterization of polyolefins is a compromising technique. Best resolution in terms of molecular weight and molecular weight distribution requires a very low sample solution concentration in size-exclusion chromatography while best results from online infrared (IR) spectroscopy require as high concentrations as possible. The signal-to-noise ratio at the IR detector could be increased significantly after application of a bandpass filter instead of a steel mesh attenuator and furthermore influences of system instabilities could be decreased by changes in data processing. Reliable short-chain branching information in the high molecular weight section in respect to accuracy and repeatability with better chromatographic resolution could be achieved.

  9. Reaction between Steel-Making Slag and Carbonaceous Materials While Mixing with High Density Polyethylene

    NASA Astrophysics Data System (ADS)

    Hong, Lan; Sahajwalla, Veena

    2016-01-01

    Since the beginning of the extensive applications in numerous high temperature processes such as iron- and steel-making, coke-making etc. partly in the place of coke, the investigation into the reaction mechanism of waste plastics has become increasingly necessary. In this paper a fundamental study on the behavior of a typical component of waste plastics, high density polyethylene (HDPE), in a mixture with coke at a 1:1 ratio in mass base was conducted during the reaction with iron oxide in steel-making slag at 1823 K and was compared with coke and graphite. The reaction mechanism of carbonaceous materials was analyzed based on the contents of CO and CO2 in the off-gas monitored by an infrared (IR) gas analyzer. It is clear from the results that the reaction of HDPE and coke mixture with steel-making slag approached equilibrium of the Boudouard reaction more quickly and closely than coke or graphite.

  10. Laser surfacing of high density polyethylene for reduction in fuel permeability

    SciTech Connect

    Duley, W.W. ); Ogmen, M.; Steel, T. ); Mihailov, S. )

    1992-01-01

    This paper reports that the increasing use of plastics by the automobile industry has resulted in new manufacturing technology. For example, high density polyethylene (HDPE) fuel tanks can now be blow-molded to fit available vehicle space. Such HDPE tanks offer several advantages over conventional metal tanks. Some of these advantages are: lower production cost; ease of fabrication and fitting to vehicle; reduced explosion hazard; 40 - 50 % reduction in weight; impact resistance; and lack of corrosion. The effect of UV and CO[sub 2] laser radiation on the surface of HDPE gas tank material in relation to the permeability of the surface to unleaded gasoline has been investigated. It is found that while excimer (UV) laser radiation has no effect on permeability, CO[sub 2] laser radiation at low intensity modifies the surface so as to reduce permeability over timescales of 1 - 2 days. A possible origin for this modification is suggested.

  11. Optical Emission Spectroscopy Characterization of Atmospheric Pressure Plasma Removal of High Density Polyethylene

    NASA Astrophysics Data System (ADS)

    McWilliams, Anthony; Shannon, Steven; Hudak, Stephen; Cuomo, Jerry

    2011-10-01

    Detailed spectroscopic measurements have been made on a hybrid vortex stabilized plasma torch probing the removal of high density polyethylene (HDPE). It has been determined that the dominant removal mechanism is related to the emission intensity of the reactive species present in the plasma through correlating the intensity of the atomic oxygen 777 nm peak with the removal rate as a function of axial distance from the torch. The studies also determined a weak correlation between removal rate and temperature. Further investigation of the removal mechanism has been based on in situ OES measurements of the plasma etching HDPE. This enables the comparison of the emission from available plasma reactants to the emission from the products resulting from either direct emission during the reaction phase or indirect reincorporation into the plasma region. Knowledge of the initial reactants and final products permits the formation of a hypothesis on the actual dominant removal mechanism or reaction pathway. Funded by SERDP WP-1762.

  12. Bioglass/high density polyethylene composite for soft tissue applications: preparation and evaluation.

    PubMed

    Wang, M; Hench, L L; Bonfield, W

    1998-12-15

    Particulate 45S5 Bioglass with an average size of 46 microm was incorporated into a high density polyethylene (HDPE) for potential medical applications. Composites with Bioglass volumes of 10, 20, and 40% were produced by a manufacturing process consisting of blending, compounding, powdering, and compression molding. The Bioglass particles were well dispersed, and their homogeneous distribution in the polymer matrix, achieved after compounding, was retained during subsequent composite processing. The Young's modulus and microhardness of the composites increased with an increase in Bioglass volume while the tensile strength and fracture strain decreased. Fourier transform infrared spectra, obtained from Bioglass/HDPE samples exposed for 20 h at 37 degrees C to a simulated body fluid (SBF-9), demonstrated that composites of all the compositions examined developed the surface biological apatite layer equivalent to that for bulk Bioglass.

  13. Interfacial thermal resistance between high-density polyethylene (HDPE) and sapphire

    NASA Astrophysics Data System (ADS)

    Zheng, Kun; Zhu, Jie; Ma, Yong-Mei; Tang, Da-Wei; Wang, Fo-Song

    2014-10-01

    To improve the thermal conductivity of polymeric composites, the numerous interfacial thermal resistance (ITR) inside is usually considered as a bottle neck, but the direct measurement of the ITR is hardly reported. In this paper, a sandwich structure which consists of transducer/high density polyethylene (HDPE)/sapphire is prepared to study the interface characteristics. Then, the ITRs between HDPE and sapphire of two samples with different HDPE thickness values are measured by time-domain thermoreflectance (TDTR) method and the results are ~ 2 × 10-7 m2·K·W-1. Furthermore, a model is used to evaluate the importance of ITR for the thermal conductivity of composites. The model's analysis indicates that reducing the ITR is an effective way of improving the thermal conductivity of composites. These results will provide valuable guidance for the design and manufacture of polymer-based thermally conductive materials.

  14. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites.

    PubMed

    Liu, Tian; Wood, Weston; Zhong, Wei-Hong

    2011-12-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials.

  15. Wet self-cleaning of superhydrophobic microfiber adhesives formed from high density polyethylene.

    PubMed

    Lee, Jongho; Fearing, Ronald S

    2012-10-30

    Biologically inspired adhesives developed for switchable and controllable adhesion often require repetitive uses in general, dirty, environments. Superhydrophobic microstructures on the lotus leaf lead to exceptional self-cleaning of dirt particles on nonadhesive surfaces with water droplets. This paper describes the self-cleaning properties of a hard-polymer-based adhesive formed with high-aspect-ratio microfibers from high-density polyethylene (HDPE). The microfiber adhesive shows almost complete wet self-cleaning of dirt particles with water droplets, recovering 98% of the adhesion of the pristine microfiber adhesives. The low contact angle hysteresis indicates that the surface of microfiber adhesives is superhydrophobic. Theoretical and experimental studies reveal a design parameter, length, which can control the adhesion without affecting the superhydrophobicity. The results suggest some properties of biologically inspired adhesives can be controlled independently by adjusting design parameters.

  16. Sensitivity of Dielectric Properties to Wear Process on Carbon Nanofiber/High-Density Polyethylene Composites

    PubMed Central

    2011-01-01

    We examined the correlation of wear effects with dielectric properties of carbon nanofibers (CNFs; untreated and organosilane-treated)-reinforced high-density polyethylene (HDPE) composites. Wear testing for the nanocomposites over up to 120 h was carried out, and then, dielectric permittivity and dielectric loss factor of the polymer composites with the increased wear time were studied. Scanning electron microscope and optical microscope observations were made to analyze the microstructure features of the nanocomposites. The results reveal that there exist approximate linear relationships of permittivity with wear coefficient for the nanocomposites. Composites containing silanized CNFs with the sufficiently thick coating exhibited high wear resistance. The change in permittivity was more sensitive to the increased wear coefficient for the nanocomposites with lower wear resistance. This work provides potential for further research on the application of dielectric signals to detect the effects of wear process on lifetime of polymeric materials. PMID:27502631

  17. Strain-rate/temperature behavior of high density polyethylene in compression

    NASA Technical Reports Server (NTRS)

    Clements, L. L.; Sherby, O. D.

    1978-01-01

    The compressive strain rate/temperature behavior of highly linear, high density polyethylene was analyzed in terms of the predictive relations developed for metals and other crystalline materials. For strains of 5 percent and above, the relationship between applied strain rate, dotted epsilon, and resulting flow stress, sigma, was found to be: dotted epsilon exp times (Q sub f/RT) = k'(sigma/sigma sub c) to the nth power; the left-hand side is the activation-energy-compensated strain rate, where Q sub f is activation energy for flow, R is gas constant, and T is temperature; k is a constant, n is temperature-independent stress exponent, and sigma/sigma sub c is structure-compensated stress. A master curve resulted from a logarithmic plot of activation-energy-compensated strain rate versus structure-compensated stress.

  18. In-situ Production of High Density Polyethylene and Other Useful Materials on Mars

    NASA Technical Reports Server (NTRS)

    Flynn, Michael

    2005-01-01

    This paper describes a revolutionary materials structure and power storage concept based on the in-situ production of abiotic carbon 4 compounds. One of the largest single mass penalties required to support the human exploration of Mars is the surface habitat. This proposal will use physical chemical technologies to produce high density polyethylene (HDPE) inflatable structures and construction materials from Mars atmospheric CO2. The formation of polyethylene from Mars CO2 is based on the use of the Sabatier and modified Fischer Tropsch reactions. The proposed system will fully integrate with existing in-situ propellant production concepts. The technology will also be capable of supplementing human caloric requirements, providing solid and liquid fuels for energy storage, and providing significant reduction in mission risk. The NASA Mars Reference Mission Definition Team estimated that a conventional Mars surface habitat structure would weigh 10 tonnes. It is estimated that this technology could reduce this mass by 80%. This reduction in mass will significantly contribute to the reduction in total mission cost need to make a Mars mission a reality. In addition the potential reduction of risk provided by the ability to produce C4 and potentially higher carbon based materials in-situ on Mars is significant. Food, fuel, and shelter are only three of many requirements that would be impacted by this research.

  19. In-situ Production of High Density Polyethylene and Other Useful Materials on Mars

    NASA Technical Reports Server (NTRS)

    Flynn, Michael

    2005-01-01

    This paper describes a revolutionary materials structure and power storage concept based on the in-situ production of abiotic carbon 4 compounds. One of the largest single mass penalties required to support the human exploration of Mars is the surface habitat. This proposal will use physical chemical technologies to produce high density polyethylene (HDPE) inflatable structures and construction materials from Mars atmospheric CO2. The formation of polyethylene from Mars CO2 is based on the use of the Sabatier and modified Fischer Tropsch reactions. The proposed system will fully integrate with existing in-situ propellant production concepts. The technology will also be capable of supplementing human caloric requirements, providing solid and liquid fuels for energy storage, and providing significant reduction in mission risk. The NASA Mars Reference Mission Definition Team estimated that a conventional Mars surface habitat structure would weigh 10 tonnes. It is estimated that this technology could reduce this mass by 80%. This reduction in mass will significantly contribute to the reduction in total mission cost need to make a Mars mission a reality. In addition the potential reduction of risk provided by the ability to produce C4 and potentially higher carbon based materials in-situ on Mars is significant. Food, fuel, and shelter are only three of many requirements that would be impacted by this research.

  20. Product distribution modelling in the thermal pyrolysis of high density polyethylene.

    PubMed

    Elordi, G; Lopez, G; Olazar, M; Aguado, R; Bilbao, J

    2007-06-18

    The thermal fast pyrolysis of high density polyethylene (HDPE) has been carried out in a conical spouted bed reactor in the 450-715 degrees C range, and individual products have been monitored with the aim of obtaining kinetic data for the design and simulation of this process at large scale. Kinetic schemes have been proposed in order to explain both the results obtained in the laboratory plant and those obtained in the literature by other authors operating at laboratory and larger scale. Discrimination has been carried out based on the contribution of the variance of model parameters (stepwise regression) to the total variance explained by the model. The models based on that of Westerhout et al. [R.W.J. Westerhout, J. Waanders, W.P.M. Van Swaaij, Recycling of polyethene and polypropene in a novel bench-scale rotating cone reactor by high-temperature pyrolysis. Ind. Eng. Chem. Res. 37 (6) (1998) 2293-2300] do not adequately predict the experimental results, especially those corresponding to aromatics and char, which is probably due to the very short residence times attained in the conical spouted bed and, consequently, to the lower yields of aromatics and char. The model of best fit is the one where polyethylene degrades to give gas, liquid (oil) and wax fractions. Furthermore, the latter undergoes secondary reactions to give liquid and aromatics, which in turn produce more char.

  1. Friction and wear of hydroxyapatite reinforced high density polyethylene against the stainless steel counterface.

    PubMed

    Wang, M; Chandrasekaran, M; Bonfield, W

    2002-06-01

    Hydroxyapatite (HA) reinforced high density polyethylene (HDPE) was invented as a biomaterial for skeletal applications. In this investigation, tribological properties (e.g. wear rate and coefficient of friction) of unfilled HDPE and HA/HDPE composites were evaluated against the duplex stainless steel in dry and lubricated conditions, with distilled water or aqueous solutions of proteins (egg albumen or glucose) being lubricants. Wear tests were conducted in a custom-built test rig for HDPE and HA/HDPE containing up to 40 vol % of HA. It was found that HA/HDPE composites had lower coefficients of friction than unfilled HDPE under certain conditions. HA/HDPE also exhibited less severe fatigue failure marks than HDPE. The degradation and fatigue failure of HDPE due to the presence of proteins were severe for low speed wear testing (100 rpm) as compared to high speed wear testing (200 rpm). This was due possibly to the high shear rate at the contact which could remove any degraded film instantaneously at high sliding speed, while with a low sliding speed the build-up of a degraded layer of protein could occur. The degraded protein layer would stay at the contact for a longer time and mechanical activation would induce adverse reactions, weakening the surface layer of HDPE. Both egg albumen and glucose were found to be corrosive to steel and adversely reactive for HDPE and HA/HDPE composites. The wear modes observed were similar to that of ultra-high molecular weight polyethylene. Specimens tested with egg albumen also displayed higher wear rates, which was again attributed to corrosion accelerated wear.

  2. Preparation and properties of banana fiber-reinforced composites based on high density polyethylene (HDPE)/Nylon-6 blends.

    PubMed

    Liu, H; Wu, Q; Zhang, Q

    2009-12-01

    Banana fiber (BaF)-filled composites based on high density polyethylene (HDPE)/Nylon-6 blends were prepared via a two-step extrusion method. Maleic anhydride grafted styrene/ethylene-butylene/styrene triblock polymer (SEBS-g-MA) and maleic anhydride grafted polyethylene (PE-g-MA) were used to enhance impact performance and interfacial bonding between BaF and the resins. Mechanical, crystallization/melting, thermal stability, water absorption, and morphological properties of the composites were investigated. In the presence of SEBS-g-MA, better strengths and moduli were found for HDPE/Nylon-6 based composites compared with corresponding HDPE based composites. At a fixed weight ratio of PE-g-MA to BaF, an increase of BaF loading up to 48.2 wt.% led to a continuous improvement in moduli and flexural strength of final composites, while impact toughness was lowered gradually. Predicted tensile modulus by the Hones-Paul model for three-dimensional random fiber orientation agreed well with experimental data at the BaF loading of 29.3 wt.%. However, the randomly-oriented fiber models underestimated experimental data at higher fiber levels. It was found that the presence of SEBS-g-MA had a positive influence on reinforcing effect of the Nylon-6 component in the composites. Thermal analysis results showed that fractionated crystallization of the Nylon-6 component in the composites was induced by the addition of both SEBS-g-MA and PE-g-MA. Thermal stability of both composite systems differed slightly, except an additional decomposition peak related to the minor Nylon-6 for the composites from the HDPE/Nylon-6 blends. In the presence of SEBS-g-MA, the addition of Nylon-6 and increased BaF loading level led to an increase in the water absorption value of the composites.

  3. Modeling benzene permeation through drinking water high density polyethylene (HDPE) pipes.

    PubMed

    Mao, Feng; Ong, Say Kee; Gaunt, James A

    2015-09-01

    Organic compounds such as benzene, toluene, ethyl benzene and o-, m-, and p-xylene from contaminated soil and groundwater may permeate through thermoplastic pipes which are used for the conveyance of drinking water in water distribution systems. In this study, permeation parameters of benzene in 25 mm (1 inch) standard inside dimension ratio (SIDR) 9 high density polyethylene (HDPE) pipes were estimated by fitting the measured data to a permeation model based on a combination of equilibrium partitioning and Fick's diffusion. For bulk concentrations between 6.0 and 67.5 mg/L in soil pore water, the concentration-dependent diffusion coefficients of benzene were found to range from 2.0×10(-9) to 2.8×10(-9) cm2/s while the solubility coefficient was determined to be 23.7. The simulated permeation curves of benzene for SIDR 9 and SIDR 7 series of HDPE pipes indicated that small diameter pipes were more vulnerable to permeation of benzene than large diameter pipes, and the breakthrough of benzene into the HDPE pipe was retarded and the corresponding permeation flux decreased with an increase of the pipe thickness. HDPE pipes exposed to an instantaneous plume exhibited distinguishable permeation characteristics from those exposed to a continuous source with a constant input. The properties of aquifer such as dispersion coefficients (DL) also influenced the permeation behavior of benzene through HDPE pipes.

  4. Wine evolution and spatial distribution of oxygen during storage in high-density polyethylene tanks.

    PubMed

    del Alamo-Sanza, María; Laurie, V Felipe; Nevares, Ignacio

    2015-04-01

    Porous plastic tanks are permeable to oxygen due to the nature of the polymers with which they are manufactured. In the wine industry, these types of tanks are used mainly for storing wine surpluses. Lately, their use in combination with oak pieces has also been proposed as an alternative to mimic traditional barrel ageing. In this study, the spatial distribution of dissolved oxygen in a wine-like model solution, and the oxygen transfer rate (OTR) of high-density polyethylene tanks (HDPE), was analysed by means of a non-invasive opto-luminescence detector. Also, the chemical and sensory evolution of red wine, treated with oak pieces, and stored in HDPE tanks was examined and compared against traditional oak barrel ageing. The average OTR calculated for these tanks was within the commonly accepted amounts reported for new barrels. With regards to wine evolution, a number of compositional and sensory differences were observed between the wines aged in oak barrels and those stored in HDPE tanks with oak barrel alternatives. The use of HDPE tanks in combination with oak wood alternatives is a viable alternative too for ageing wine. © 2014 Society of Chemical Industry.

  5. Separation of bimodal high density polyethylene using multidimensional high temperature liquid chromatography.

    PubMed

    Prabhu, K N; Brüll, R; Macko, T; Remerie, K; Tacx, J; Garg, P; Ginzburg, A

    2015-11-06

    High-temperature two-dimensional liquid chromatography (HT 2D-LC) using HT-HPLC as first dimension and HT-SEC as second dimension holds enormous potential to investigate the distribution according to molar mass and chemical composition of bimodal high density polyethylene (BiHDPE), as it avoids drawbacks of crystallization-based techniques. In this study, we have stepwise optimized the chromatographic parameters of 1D, comprising gradient slope and temperature, using model homo- and copolymers of ethylene with the aim to minimize the impact of molar mass on the compositional separation. Then the HT-HPLC was hyphenated to HT-SEC and optimum conditions for the volume of the sample transfer loop were probed with regard to the resolution of BiHDPE into the individual constituents HDPE and LLDPE. A particular important aspect was the use of infrared (IR) detection, and the demands it puts on the chromatographic aspects: We have shown that IR detection can be successfully applied in HT 2D-LC of BiHDPE, which is broadly distributed with regard to short chain branching and molar mass, only when the separation in 2D is optimized with regard to chromatographic resolution. As final result a bimodality is evident in the contour and the 3D surface plots as well as in both HPLC and SEC projections generated from HT 2D-LC.

  6. Preparation and Compatibility Evaluation of Polypropylene/High Density Polyethylene Polyblends

    PubMed Central

    Lin, Jia-Horng; Pan, Yi-Jun; Liu, Chi-Fan; Huang, Chien-Lin; Hsieh, Chien-Teng; Chen, Chih-Kuang; Lin, Zheng-Ian; Lou, Ching-Wen

    2015-01-01

    This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). The SEM results show that PP and HDPE are incompatible polymers with PP being a continuous phase and HDPE being a dispersed phase. The FTIR results show that the combination of HDPE does not influence the chemical structure of PP, indicating that the polyblends are made of a physical blending. The DSC and XRD results show that PP and HDPE are not compatible, and the combination of HDPE is not correlated with the crystalline structure and stability of PP. The PLM results show that the combination of HDPE causes stacking and incompatibility between HDPE and PP spherulites, and PP thus has incomplete spherulite morphology and a smaller spherulite size. However, according to mechanical property test results, the combination of HDPE improves the impact strength of PP. PMID:28793750

  7. [Attenuated Total Reflection Infrared Spectroscopy for Degradation Profile of High Density Polyethylene after Weathering Aging].

    PubMed

    Guo, Jun-jun; Yan, Hua; Bao, He-bin; Wang, Xue-mei; Hu, Zhi-de; Yang, Jian-jian

    2015-06-01

    High density polyethylene (HDPE) was widely used as rotational packaging case in the material reserve field. The chemical changes of HDPE, exposed to particular climatic conditions of tropic marine atmosphere for one year-long in Wanning Hainan, were elucidated by the attenuated total reflection infrared spectroscopy (ATR-FTIR). The structural changes were studied qualitatively, mainly from the polymeric chain breaking, branching and oxidation to distinguish the degradation profile. The variations of crystallinity & carbonyl index were also studied quantitatively according to the characteristic peaks intensity & area ratio. Finally, the relationships between structural changes and mechanical properties were investigated. The results showed that the polymeric chain breaking & branching play a leading role before 3 months in the aging progress. Then oxidation phenomena gradually takes place during 3-6 months. The chain branching & oxidation were predominant factors after 6 months. Nine months later, the oxidation was saturated gradually. Furthermore, the aging process is positively correlated to the temperature and irradiation. After 12 months aging, the carbonyl index increased by 112 times and crystallinity was 10% higher than before. The tensile/bending modulus deceased faster than tensile/bending strength of HDPE. The linear degree of tensile modulus and carbonyl index was 0.97. The degree of linearity of tensile strength and crystallinity calculated by feature bands (720-730 cm(-1)) was 0.96. It showed that the mechanical properties of HDPE can be speculated from the structural changes by ATR-FTIR.

  8. Preparation and Compatibility Evaluation of Polypropylene/High Density Polyethylene Polyblends.

    PubMed

    Lin, Jia-Horng; Pan, Yi-Jun; Liu, Chi-Fan; Huang, Chien-Lin; Hsieh, Chien-Teng; Chen, Chih-Kuang; Lin, Zheng-Ian; Lou, Ching-Wen

    2015-12-17

    This study proposes melt-blending polypropylene (PP) and high density polyethylene (HDPE) that have a similar melt flow index (MFI) to form PP/HDPE polyblends. The influence of the content of HDPE on the properties and compatibility of polyblends is examined by using a tensile test, flexural test, Izod impact test, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), polarized light microscopy (PLM), and X-ray diffraction (XRD). The SEM results show that PP and HDPE are incompatible polymers with PP being a continuous phase and HDPE being a dispersed phase. The FTIR results show that the combination of HDPE does not influence the chemical structure of PP, indicating that the polyblends are made of a physical blending. The DSC and XRD results show that PP and HDPE are not compatible, and the combination of HDPE is not correlated with the crystalline structure and stability of PP. The PLM results show that the combination of HDPE causes stacking and incompatibility between HDPE and PP spherulites, and PP thus has incomplete spherulite morphology and a smaller spherulite size. However, according to mechanical property test results, the combination of HDPE improves the impact strength of PP.

  9. Characterization of laser beam transmission through a High Density Polyethylene (HDPE) plate

    NASA Astrophysics Data System (ADS)

    Genna, S.; Leone, C.; Tagliaferri, V.

    2017-02-01

    Infrared (IR) light propagation in semicrystalline polymers involves mechanisms such as reflection, transmission, absorption and internal scattering. These different rates determine either the interaction mechanism, either the temperatures reached in the IR heating processes. Consequently, the knowledge of these rates is fundamental in the development of IR heating processes in order to avoid the polymer's damage and to increase the process energy efficiency. Aim of this work is to assess a simple procedure to determine the rates of absorbed, reflected, transmitted and scattered energy in the case of an unfilled High Density Polyethylene (HDPE) plate. Experimental tests were performed by exposing a HDPE plate, 3 mm in thickness, to a diode laser source, working at the fundamental wavelength of 975 nm. The transmitted power was measured by power meter, the reflected one by applying the Beer-Lambert law to sample of different thickness. IR thermal images were adopted to measure the absorbed ratio. The scattered ratio was measured by energetic balance, as difference between the incoming power and the other ratios. Finally, IR thermal images were adopted to measure the scattered ratio and to validate the procedure.

  10. Biodegradation of thermally treated high-density polyethylene (HDPE) by Klebsiella pneumoniae CH001.

    PubMed

    Awasthi, Shraddha; Srivastava, Pratap; Singh, Pardeep; Tiwary, D; Mishra, Pradeep Kumar

    2017-10-01

    Biodegradation of plastics, which are the potential source of environmental pollution, has received a great deal of attention in the recent years. We aim to screen, identify, and characterize a bacterial strain capable of degrading high-density polyethylene (HDPE). In the present study, we studied HDPE biodegradation using a laboratory isolate, which was identified as Klebsiella pneumoniae CH001 (Accession No MF399051). The HDPE film was characterized by Universal Tensile Machine (UTM), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) before and after microbial incubation. We observed that this strain was capable of adhering strongly on HDPE surface and form a thick biofilm, when incubated in nutrient broth at 30 °C on 120 rpm for 60 days. UTM analysis showed a significant decrease in weight (18.4%) and reduction in tensile strength (60%) of HDPE film. Furthermore, SEM analysis showed the cracks on the HDPE surface, whereas AFM results showed an increase in surface roughness after bacterial incubation. Overall, these results indicate that K. pneumoniae CH001 can be used as potential candidate for HDPE degradation in eco-friendly and sustainable manner in the environment.

  11. Shape stabilised phase change materials (SSPCMs): High density polyethylene and hydrocarbon waxes

    SciTech Connect

    Mu, Mulan E-mail: m.basheer@qub.ac.uk; Basheer, P. A. M. E-mail: m.basheer@qub.ac.uk; Bai, Yun; McNally, Tony

    2014-05-15

    Shape stabilised phase change materials (SSPCMs) based on high density polyethylene (HDPE) with high (HPW, T{sub m}=56-58 °C) and low (L-PW, T{sub m}=18-23 °C) melting point waxes were prepared by melt-mixing in a twin-screw extruder and their potential in latent heat thermal energy storage (LHTES) applications for housing assessed. The structure and morphology of these blends were investigated by scanning electron microscopy (SEM). Both H-PW and L-PW were uniformly distributed throughout the HDPE matrix. The melting point and latent heat of the SSPCMs were determined by differential scanning calorimetry (DSC). The results demonstrated that both H-PW and L-PW have a plasticisation effect on the HDPE matrix. The tensile and flexural properties of the samples were measured at room temperature (RT, 20±2 °C) and 70 °C, respectively. All mechanical properties of HDPE/H-PW and HDPE/L-PW blends decreased from RT to 70 °C. In all instances at RT, modulus and stress, irrespective of the mode of deformation was greater for the HDPE/H-PW blends. However, at 70 °C, there was no significant difference in mechanical properties between the HDPE/H-PW and HDPE/L-PW blends.

  12. Materials and QC issues for high density polyethylene thermoplastic tank, sump, and trench lining installations

    SciTech Connect

    Zarnitz, C.; Peggs, I.D.

    1999-11-01

    High Density Polyethylene (HDPE) is used as a chemical-resistant material of construction to line tanks, sumps, and trenches. Typical applications for mechanically attached HDPE linings would include trenches to convey wash-downs in chemical process areas, sumps to contain mixed hazardous wastes, storage of chemical process reagents, containment of landfill leachate, secondary containment, and lining of waste processing vessels. Special concerns exist as to material choice and use of HDPE that will resist the tendency to stress crack as well as methods to measure stress-cracking resistance. Assurances are needed in these critical applications that proper materials have been chosen and used by the installer. This paper reviews some of the more important concerns that relate to the use and installation of HDPE liners for chemically resistant applications and how these concerns are addressed. Special focus will be placed on methods used to predict stress-cracking resistance and on procedures to use to certify to the customer that qualified materials are used.

  13. Considerations for cold weather construction using high density polyethylene for corrosion control systems

    SciTech Connect

    Szklarz, K.E.; Baron, J.J.

    1995-12-01

    High Density Polyethylene (HDPE) is commonly used as material for corrosion-resistant piping in the petroleum industry. It is used as thick-walled self-supporting linepipes, as internal liners for steel linepipe, and as protective jackets for insulated linepipes. In Canada, it is not uncommon for operations, such as pipeline installation, to be performed during the winter season when temperatures are in the 0 C to {minus}20 C range. Brittle failures of HDPE materials have been experienced during such sub-zero operations, particularly when pipe handling and bending is involved. This study evaluated the changes in HDPE mechanical properties within the temperature range of 10 C to {minus}40 C to understand any embrittlement phenomena that may be occurring. HDPE undergoes substantial increases in modulus and strength at lower temperatures and increasing strain rate. The changes are gradual and over a wide range of temperature with no sharp cut-off temperature at which brittle behavior will occur. Flexural properties behave in a similar manner. A notch, causing a local increased strain rate, has a significant effect on the failure behavior of HDPE material with a gradual transition in behavior of ductility and load at below 0 C.

  14. Current Activities Assessing Butt Fusion Joint Integrity in High Density Polyethylene Piping

    SciTech Connect

    Crawford, Susan L.; Cinson, Anthony D.; Doctor, Steven R.; Denslow, Kayte M.

    2012-09-01

    The Pacific Northwest National Laboratory (PNNL) in Richland, Washington, conducted initial studies to evaluate the effectiveness of nondestructive examinations (NDE) coupled with mechanical testing for assessing butt fusion joint integrity in high density polyethylene (HDPE) pipe. The work provided insightful information to the United States Nuclear Regulatory Commission (NRC) on the effectiveness of volumetric inspection techniques for detecting lack of fusion (LOF) conditions in the fusion joints. HDPE has been installed on a limited basis in American Society of Mechanical Engineers (ASME) Class 3, buried piping systems at several operating U.S. nuclear power plants and has been proposed for use in new construction. A comparison was made between the results from ultrasonic and microwave nondestructive examinations and the results from mechanical destructive evaluations, specifically the high-speed tensile test and the side-bend test, for determining joint integrity. The data comparison revealed that none of the NDE techniques detected all of the lack-of-fusion conditions that were revealed by the destructive tests. Follow-on work has recently been initiated at PNNL to accurately characterize the NDE responses from machined flaws of varying size and location in PE 4710 materials as well as the LOF condition. This effort is directed at quantifying the ability of volumetric NDE techniques to detect flaws in relation to the critical flaw size associated with joint integrity. A status of these latest investigations is presented.

  15. Sorption Isotherm of Southern Yellow Pine—High Density Polyethylene Composites

    PubMed Central

    Liu, Feihong; Han, Guangping; Cheng, Wanli; Wu, Qinglin

    2015-01-01

    Temperature and relative humidity (RH) are two major external factors, which affect equilibrium moisture content (EMC) of wood-plastic composites (WPCs). In this study, the effect of different durability treatments on sorption and desorption isotherms of southern yellow pine (SYP)-high density polyethylene (HDPE) composites was investigated. All samples were equilibriumed at 20 °C and various RHs including 16%, 33%, 45%, 66%, 75%, 85%, 93%, and100%. EMCs obtained from desorption and absorption for different WPC samples were compared with Nelson’s sorption isotherm model predictions using the same temperature and humidity conditions. The results indicated that the amount of moisture absorbed increased with the increases in RH at 20 °C. All samples showed sorption hysteresis at a fixed RH. Small difference between EMC data of WPC samples containing different amount of ultraviolet (UV) stabilizers were observed. Similar results were observed among the samples containing different amount of zinc borate (ZB). The experimental data of EMCs at various RHs fit to the Nelson’s sorption isotherm model well. The Nelson’s model can be used to predicate EMCs of WPCs under different RH environmental conditions. PMID:28787943

  16. Dielectric, thermal and mechanical properties of zirconium silicate reinforced high density polyethylene composites for antenna applications.

    PubMed

    Varghese, Jobin; Nair, Dinesh Raghavan; Mohanan, Pezholil; Sebastian, Mailadil Thomas

    2015-06-14

    A low cost and low dielectric loss zirconium silicate (ZrSiO4) reinforced HDPE (high-density polyethylene) composite has been developed for antenna applications. The 0-3 type composite is prepared by dispersing ZrSiO4 fillers for various volume fractions (0.1 to 0.5) in the HDPE matrix by the melt mixing process. The composite shows good microwave dielectric properties with a relative permittivity of 5.6 and a dielectric loss of 0.003 at 5 GHz at the maximum filler loading of 0.5 volume fraction. The composite exhibits low water absorption, excellent thermal and mechanical properties. It shows a water absorption of 0.03 wt%, a coefficient of thermal expansion of 70 ppm per °C and a room temperature thermal conductivity of 2.4 W mK(-1). The composite shows a tensile strength of 22 MPa and a microhardness of 13.9 kg mm(-2) for the filler loading of 0.5 volume fraction. The HDPE-ZrSiO4 composites show good dielectric, thermal and mechanical properties suitable for microwave soft substrate applications. A microstrip patch antenna is designed and fabricated using the HDPE-0.5 volume fraction ZrSiO4 substrate and the antenna parameters are investigated.

  17. Catalytic co-pyrolysis of waste vegetable oil and high density polyethylene for hydrocarbon fuel production.

    PubMed

    Wang, Yunpu; Dai, Leilei; Fan, Liangliang; Cao, Leipeng; Zhou, Yue; Zhao, Yunfeng; Liu, Yuhuan; Ruan, Roger

    2017-03-01

    In this study, a ZrO2-based polycrystalline ceramic foam catalyst was prepared and used in catalytic co-pyrolysis of waste vegetable oil and high density polyethylene (HDPE) for hydrocarbon fuel production. The effects of pyrolysis temperature, catalyst dosage, and HDPE to waste vegetable oil ratio on the product distribution and hydrocarbon fuel composition were examined. Experimental results indicate that the maximum hydrocarbon fuel yield of 63.1wt. % was obtained at 430°C, and the oxygenates were rarely detected in the hydrocarbon fuel. The hydrocarbon fuel yield increased when the catalyst was used. At the catalyst dosage of 15wt.%, the proportion of alkanes in the hydrocarbon fuel reached 97.85wt.%, which greatly simplified the fuel composition and improved the fuel quality. With the augment of HDPE to waste vegetable oil ratio, the hydrocarbon fuel yield monotonously increased. At the HDPE to waste vegetable oil ratio of 1:1, the maximum proportion (97.85wt.%) of alkanes was obtained. Moreover, the properties of hydrocarbon fuel were superior to biodiesel and 0(#) diesel due to higher calorific value, better low-temperature low fluidity, and lower density and viscosity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Shape stabilised phase change materials (SSPCMs): High density polyethylene and hydrocarbon waxes

    NASA Astrophysics Data System (ADS)

    Mu, Mulan; Basheer, P. A. M.; Bai, Yun; McNally, Tony

    2014-05-01

    Shape stabilised phase change materials (SSPCMs) based on high density polyethylene (HDPE) with high (HPW, Tm=56-58 °C) and low (L-PW, Tm=18-23 °C) melting point waxes were prepared by melt-mixing in a twin-screw extruder and their potential in latent heat thermal energy storage (LHTES) applications for housing assessed. The structure and morphology of these blends were investigated by scanning electron microscopy (SEM). Both H-PW and L-PW were uniformly distributed throughout the HDPE matrix. The melting point and latent heat of the SSPCMs were determined by differential scanning calorimetry (DSC). The results demonstrated that both H-PW and L-PW have a plasticisation effect on the HDPE matrix. The tensile and flexural properties of the samples were measured at room temperature (RT, 20±2 °C) and 70 °C, respectively. All mechanical properties of HDPE/H-PW and HDPE/L-PW blends decreased from RT to 70 °C. In all instances at RT, modulus and stress, irrespective of the mode of deformation was greater for the HDPE/H-PW blends. However, at 70 °C, there was no significant difference in mechanical properties between the HDPE/H-PW and HDPE/L-PW blends.

  19. Diffusion of multiwall carbon nanotubes (MWCNTs) through a high density polyethylene (HDPE) geomembrane.

    PubMed

    Saheli, P T; Rowe, R K; Petersen, E J; O'Carroll, D M

    2017-05-01

    The new applications for carbon nanotubes (CNTs) in various fields and consequently their greater production volume have increased their potential release to the environment. Landfills are one of the major locations where carbon nanotubes are expected to be disposed and it is important to ensure that they can limit the release of CNTs. Diffusion of multiwall carbon nanotubes (MWCNTs) dispersed in an aqueous media through a high-density polyethylene (HDPE) geomembrane (as a part of the landfill barrier system) was examined. Based on the laboratory tests, the permeation coefficient was estimated to be less than 5.1×10(-15) m(2)/s. The potential performance of a HDPE geomembrane and geosynthetic clay liner (GCL) as parts of a composite liner in containing MWCNTs was modelled for six different scenarios. The results suggest that the low value of permeation coefficient of an HDPE geomembrane makes it an effective diffusive barrier for MWCNTs and by keeping the geomembrane defects to minimum during the construction (e.g., number of holes and length of wrinkles) a composite liner commonly used in municipal solid waste landfills will effectively contain MWCNTs.

  20. PORTSMOUTH ON-SITE DISPOSAL CELL HIGH DENSITY POLYETHYLENE GEOMEMBRANE LONGEVITY

    SciTech Connect

    Phifer, M.

    2012-01-31

    It is anticipated that high density polyethylene (HDPE) geomembranes will be utilized within the liner and closure cap of the proposed On-Site Disposal Cell (OSDC) at the Portsmouth Gaseous Diffusion Plant. The likely longevity (i.e. service life) of HDPE geomembranes in OSDC service is evaluated within the following sections of this report: (1) Section 2.0 provides an overview of HDPE geomembranes, (2) Section 3.0 outlines potential HDPE geomembranes degradation mechanisms, (3) Section 4.0 evaluates the applicability of HDPE geomembrane degradation mechanisms to the Portsmouth OSDC, (4) Section 5.0 provides a discussion of the current state of knowledge relative to the longevity (service life) of HDPE geomembranes, including the relation of this knowledge to the Portsmouth OSDC, and (5) Section 6.0 provides summary and conclusions relative to the anticipated service life of HDPE geomembranes in OSDC service. Based upon this evaluation it is anticipated that the service life of HDPE geomembranes in OSDC service would be significantly greater than the 200 year service life assumed for the OSDC closure cap and liner HDPE geomembranes. That is, a 200 year OSDC HDPE geomembrane service life is considered a conservative assumption.

  1. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    SciTech Connect

    Xiang, Dong; Harkin-Jones, Eileen; Linton, David

    2015-05-22

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1∼2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  2. Impact of using high-density polyethylene geomembrane layer as landfill intermediate cover on landfill gas extraction.

    PubMed

    Chen, Zezhi; Gong, Huijuan; Zhang, Mengqun; Wu, Weili; Liu, Yu; Feng, Jin

    2011-05-01

    Clay is widely used as a traditional cover material for landfills. As clay becomes increasingly costly and scarce, and it also reduces the storage capacity of landfills, alternative materials with low hydraulic conductivity are employed. In developing countries such as China, landfill gas (LFG) is usually extracted for utilization during filling stage, therefore, the intermediate covering system is an important part in a landfill. In this study, a field test of LFG extraction was implemented under the condition of using high-density polyethylene (HDPE) geomembrane layer as the only intermediate cover on the landfill. Results showed that after welding the HDPE geomembranes together to form a whole airtight layer upon a larger area of landfill, the gas flow in the general pipe increased 25% comparing with the design that the HDPE geomembranes were not welded together, which means that the gas extraction ability improved. However as the heat isolation capacity of the HDPE geomembrane layer is low, the gas generation ability of a shallow landfill is likely to be weakened in cold weather. Although using HDPE geomembrane layer as intermediate cover is acceptable in practice, the management and maintenance of it needs to be investigated in order to guarantee its effective operation for a long term. Copyright © 2010 Elsevier Ltd. All rights reserved.

  3. Effect of cooling rate on the properties of high density polyethylene/multi-walled carbon nanotube composites

    NASA Astrophysics Data System (ADS)

    Xiang, Dong; Harkin-Jones, Eileen; Linton, David

    2015-05-01

    High density polyethylene (HDPE)/multi-walled carbon nanotube (MWCNT) nanocomposites were prepared by melt mixing using twin-screw extrusion. The extruded pellets were compression moulded at 200°C for 5min followed by cooling at different cooling rates (20°C/min and 300°C/min respectively) to produce sheets for characterization. Scanning electron microscopy (SEM) shows that the MWCNTs are uniformly dispersed in the HDPE. At 4 wt% addition of MWCNTs composite modulus increased by over 110% compared with the unfilled HDPE (regardless of the cooling rate). The yield strength of both unfilled and filled HDPE decreased after rapid cooling by about 10% due to a lower crystallinity and imperfect crystallites. The electrical percolation threshold of composites, irrespective of the cooling rate, is between a MWCNT concentration of 1˜2 wt%. Interestingly, the electrical resistivity of the rapidly cooled composite with 2 wt% MWCNTs is lower than that of the slowly cooled composites with the same MWCNT loading. This may be due to the lower crystallinity and smaller crystallites facilitating the formation of conductive pathways. This result may have significant implications for both process control and the tailoring of electrical conductivity in the manufacture of conductive HDPE/MWCNT nanocomposites.

  4. Facial reconstruction using porous high-density polyethylene (medpor): long-term results.

    PubMed

    Niechajev, Igor

    2012-08-01

    Medpor is a biocompatible, porous, high-density polyethylene implant material used as a skeleton substitute. During the last two decades, it has been successfully applied for aesthetic contour enhancement and at reconstruction of the facial skeleton. Reports on the long-term host tissue tolerance of Medpor are sparse. Use of foreign materials in nasal reconstruction has always been and still is controversial. The main contra-argument maintains that it is not known how alloplastic materials are tolerated by the human body in the long term. This study brings such data concerning the biocompatibility of Medpor. The author has 16 years of experience working with Medpor implants, including its use in rhinoplasty, chin augmentation, and malar augmentation. In this prospective study from 1996 to 2012, Medpor was used in 118 implants for 102 patients. The most frequent indications were nose deformity (n=61), chin hypoplasia (n=33), and malar hypoplasia (n=6). The follow-up periods ranged from 6 months to 15 years (median, 7 years). Of 42 difficult nasal reconstructions performed with the assistance of Medpor, 28 were catastrophe noses that had undergone two to four previous surgeries elsewhere. A total of 19 patients had saddle nose deformity. Of the nasal reconstructions, 85 % had a smooth clinical course, with results remaining stable during the observation time. Five biopsies confirmed soft tissue ingrowths and collagen deposition, with subsequent vascularization. All complications could be mastered. Two dorsal struts and two chin implants required trimming. Infection occurred in three rhinoplasty cases, and partial extrusion occurred in two cases. All augmented chins and malar prominences were firm and bony-like at palpation. Of the 106 Medpor implants in the followed-up patients, some were trimmed or removed, but 97 implants (91%) remained unchanged. Implantation of porous polyethylene in the facial region is a safe procedure. Currently, Medpor seems to be the best

  5. Photodegradation and photostabilization of weathered wood flour filled polyethylene composites

    NASA Astrophysics Data System (ADS)

    Stark, Nicole M.

    2003-06-01

    Wood plastic composites (WPCs) have gained popularity as building materials because of their usefulness in replacing solid wood in a variety of applications. These composites are promoted as being low-maintenance, high-durability products. However, it has been shown that WPCs exposed to weathering may experience a color change and/or loss in mechanical properties. An important requirement for building materials used in outdoor applications is the retention of their aesthetic qualities and mechanical properties during service life. Therefore, it is critical to understand the photodegradation mechanisms of WPCs exposed to UV radiation and to develop approaches to stabilize these composites against ultraviolet light. In this dissertation, the surface chemistries of weathered composites (both unstabilized and stabilized) as well as the effect of weathering on the color fade and the retention of mechanical properties were characterized. Since different methods of manufacturing WPCs lead to different surface characteristics, which can influence weathering, the effect of manufacturing method on the photodegradation of WPCs was investigated first. Wood flour (WF) filled high-density polyethylene (HDPE) composite samples were either injection molded, extruded, or extruded and then planed. Fourier transform infrared (FTIR) spectroscopy was used to monitor the surface chemistry of the manufactured composites. The spectra showed that the surface of planed samples had more wood component than extruded and injection molded samples, respectively. After weathering, the samples were analyzed for color fade, and loss of flexural properties. The final lightness of the composites was not dependent upon the manufacturing method. However the mechanical property loss was dependent upon manufacturing method. The samples with more wood component at the surface (planed samples) experienced a larger percent of total loss in flexural properties after weathering due to a greater effect of

  6. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    NASA Astrophysics Data System (ADS)

    Aras, Neny Rasnyanti M.; Arcana, I. Made

    2015-09-01

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm-1 which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese stearate

  7. Synthesis of manganese stearate for high density polyethylene (HDPE) and its biodegradation

    SciTech Connect

    Aras, Neny Rasnyanti M. Arcana, I Made

    2015-09-30

    An oxidant additive is one type of additive used for oxo-biodegradable polymers. This additive was prepared by reaction multivalent transition metals and fatty acids to accelerate the degradation process of polymers by providing a thermal treatment or irradiation with light. This study focused on the synthesis of manganese stearate as an additive for application in High Density Polyethylene (HDPE), and the influence of manganese stearate on the characteristics of HDPE including their biodegradability. Manganese stearate was synthesized by the reaction of stearic acid with sodium hydroxide, and sodium stearate formed was reacted with manganese chloride tetrahydrate to form manganese stearate with a melting point of 100-110 °C. Based on the FTIR spectrum showed absorption peak at wave number around 1560 cm{sup −1} which is an asymmetric vibration of CO functional group that binds to the manganese. The films of oxo-biodegradable polymer were prepared by blending HDPE and manganese stearate additives at various concentrations with using the polymer melting method, followed heating at a temperature of 50°C and 70°C for 10 days. The characterizations of the oxo-biodegradable polymers were carried out by analysis the functional groups (FTIR and ATR),thermal properties (TGA), surface properties (SEM), as well as analysis of the biodegradability (the biodegradation test by using activated sludge, % weight loss). Based on COi indicate that the additive of manganese stearate is active in oxidizing polymer by heating treatment. Results of biodegradation by microorganisms from activated sludge showed that the percentage weight loss of polymers increase with the increasing incubation time and the concentration of manganese stearate in HDPE. Biodegradability of HDPE with the addition of manganese stearate and followed by heating at a higher temperature was better observed. The highest percentage weight loss was obtained at the polymer with concentration of 0.2% manganese

  8. Degradation of lindane and hexachlorobenzene in supercritical carbon dioxide using palladium nanoparticles stabilized in microcellular high-density polyethylene.

    PubMed

    Wu, Bei-Zen; Chen, GuanYu; Yak, HwaKwang; Liao, Weisheng; Chiu, KongHwa; Peng, Shie-Ming

    2016-06-01

    Palladium nanoparticles stabilized in microcellular high-density polyethylene prepared through supercritical foaming, supercritical impregnation, and H2 reduction are used for the hydrodechlorination of lindane and hexachlorobenzene in supercritical carbon dioxide below 100 °C. Both lindane and hexachlorobenzene can be almost 100% transformed to cyclohexane in 1 h. Reaction intermediates, such as lower chlorinated products or benzene, are not observed or exist in trace amount indicating that most of them may undergo reactions without leaving the metal surface.

  9. [Study on biocompatibility of hydroxyapatite/high density polyethylene (HA/HDPE) nano-composites artificial ossicle].

    PubMed

    Wang, Guohui; Zhu, Shaihong; Tan, Guolin; Zhou, Kechao; Huang, Suping; Zhao, Yanzhong; Li, Zhiyou; Huang, Boyun

    2008-06-01

    This study was aimed to evaluate the biocompatibility of Hydroxyapatite/High density polyethylene (HA/ HDPE) nano-composites artificial ossicle. The percentage of S-period cells were detected by flow cytometry after L929 cells being incubated with extraction of the HA/HDPE nano-composites; the titanium materials for clinical application served as the contrast. In addition, both materials were implanted in animals and the histopathological evaluations were conducted. There were no statistically significant differences between the two groups (P >0.05). The results demonstrated that the HA/HDPE nano-composite artificial ossicle made by our laboratory is of a good biocompatibility and clinical application outlook.

  10. Thermal and optical excitation of trapped electrons in high-density polyethylene (HDPE) studied through positron annihilation

    NASA Astrophysics Data System (ADS)

    Nahid, F.; Zhang, J. D.; Yu, T. F.; Ling, C. C.; Fung, S.; Beling, C. D.

    2011-04-01

    Positronium (Ps) formation in high-density polyethylene (HDPE) has been studied below the glass transition temperature. The formation probability increases with positron irradiation time due to an increasing number of inter-track trapped electrons becoming available for positron capture. The temperature variation of the saturated Ps level is discussed in different models. The quenching of trapped electrons by light has been studied and the optical de-trapping cross-section for different photon energies has been estimated over the visible region.

  11. Effect of oxyfluorinated multi-walled carbon nanotube additives on positive temperature coefficient/negative temperature coefficient behavior in high-density polyethylene polymeric switches

    SciTech Connect

    Bai, Byong Chol; Kang, Seok Chang; Im, Ji Sun; Lee, Se Hyun; Lee, Young-Seak

    2011-09-15

    Graphical abstract: The electrical properties of MWCNT-filled HDPE polymeric switches and their effect on oxyfluorination. Highlights: {yields} Oxyfluorinated MWCNTs were used to reduce the PTC/NTC phenomenon in MWCNT-filled HDPE polymeric switches. {yields} Electron mobility is difficult in MWCNT particles when the number of oxygen functional groups (C-O, C=O) increases by oxyfluorination. {yields} A mechanism of improved electrical properties of oxyfluorinated MWCNT-filled HDPE polymeric switches was suggested. -- Abstract: Multi-walled carbon nanotubes (MWCNTs) were embedded into high-density polyethylene (HDPE) to improve the electrical properties of HDPE polymeric switches. The MWCNT surfaces were modified by oxyfluorination to improve their positive temperature coefficient (PTC) and negative temperature coefficient (NTC) behaviors in HDPE polymeric switches. HDPE polymeric switches exhibit poor electron mobility between MWCNT particles when the number of oxygen functional groups is increased by oxyfluorination. Thus, the PTC intensity of HDPE polymeric switches was increased by the destruction of the electrical conductivity network. The oxyfluorination of MWCNTs also leads to weak NTC behavior in the MWCNT-filled HDPE polymeric switches. This result is attributed to the reduction of the mutual attraction between the MWCNT particles at the melting temperature of HDPE, which results from a decrease in the surface free energy of the C-F bond in MWCNT particles.

  12. Measurement and Ranking of Permeation Specimen Thickness Profiles: High-Density Polyethylene Swatches

    DTIC Science & Technology

    2016-05-01

    material was composed of Dow Continuum DGDC-2480 BK bimodal polyethylene resin (Dow Chemical Company; Midland, MI). The UMSCs were produced from preformed...pipe, and the end caps were machined from blocks of the same resin . The resin was composed of a >99% ethylene/hexene-1 copolymer with CAS no. 25213...Shuely, W.J.; Brletich, R.W.; Henshaw, J.M. Solvent Effects on the Tensile Properties of Thermoplastic Composites . In Proceedings of the 1991

  13. Slip-additive migration, surface morphology, and performance on injection moulded high-density polyethylene closures.

    PubMed

    Dulal, Nabeen; Shanks, Robert; Gengenbach, Thomas; Gill, Harsharn; Chalmers, David; Adhikari, Benu; Pardo Martinez, Isaac

    2017-11-01

    The amount and distribution of slip agents, erucamide, and behenamide, on the surface of high-density polyethene, is determined by integral characteristics of slip agent structure and polymer morphology. A suite of surface analysis techniques was applied to correlate physicochemical properties with slip-additive migration behaviour and their surface morphology. The migration, surface morphology and physicochemical properties of the slip additives, crystallinity and orientation of polyethene spherulites and interaction between slip additives and high-density polyethene influence the surface characteristics. The high-density polyethene closures were produced with erucamide and behenamide separately and stored until they produced required torque. Surface composition was determined employing spectroscopy and gas chromatography. The distribution of additives was observed under optical, scanning electron and atomic force microscopes. The surface energy, crystallinity and application torque were measured using contact angle, differential scanning calorimeter and a torque force tester respectively. Each slip additive produced a characteristic amide peak at 1645cm(-1) in infrared spectroscopy and peaks of oxygen and nitrogen in X-ray photoelectron spectroscopy, suggesting their presence on the surface. The erucamide produced placoid scale-like structures and behenamide formed denticulate structures. The surface erucamide and behenamide responsible for reducing the torque was found to be 15.7µg/cm(2) and 1.7µg/cm(2). Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Effective Blending of Ultrahigh Molecular Weight Polyethylene with High-Density Polyethylene via Solid-State Shear Pulverization (SSSP)

    NASA Astrophysics Data System (ADS)

    Diop, Mirian; Torkelson, John

    2014-03-01

    Compared with conventional polyolefins, ultrahigh molecular weight polyethylene (UHMWPE) possesses outstanding mechanical properties, including impact strength and crack resistance, that make it it highly desirable for applications ranging from body armor to implants. Unfortunately, UHMWPE has an ultrahigh melt viscosity that renders common melt processes ineffective for making products from UHMWPE. Attempts to overcome this problem by blending UHMWPE with polyethylene (PE) by conventional melt mixing have been unsuccessful because of the enormous viscosity mismatch between blend components and have led to large suspensions of UHMWPE particles within a PE matrix. Here, we show the utility of solid-state shear pulverization (SSSP) in achieving effectively and intimately mixed UHMWPE/PE blends. For blends with up to 50 wt% UHMWPE we observe only slight increases in viscosity (η) at high shear rates but major increases in η with increasing UHMWPE content at low shear rates. Using extensional rheology, we confirm the strain hardening behavior of SSSP blends. Additionally, shear rheology and differential scanning calorimetry data indicate that the degree of mixing between UHMWPE and HDPE domains can be increased dramatically with subsequent passes of SSSP and single screw extrusion. Finally, blends prepared via SSSP show dramatic increases in impact strength; e.g., for a 30/70 wt% UHMWPE/HDPE blend, impact strength increases by about 300 % (relative to the parent neat HDPE).

  15. [The experimental assessment of high-density ultrahigh molecular weight polyethylene for the prosthetic treatment of auditory ossicles].

    PubMed

    Khorov, O G; Struk, V A; Novoseletskiĭ, V A

    2013-01-01

    The objective of the present study was the comparative assessment of the influence of titanium and high-density ultrahigh molecular weight polyethylene (HDMPE) on the selected biochemical and immunological properties of blood and morphological features of the middle ear tissues in experimental animals. A total of 35 rabbits used were allocated to 3 groups. Groups 1 and 2 included 15 animals each. They were involved in three series of experiments (5 animals per series lasting 15, 60, and 90 days). Group 3 was comprised of 5 animals. Prosthetic treatment of auditory ossicles was performed using implants from modified high-density ultrahigh molecular weight polyethylene (group 1) and titanium implants (group 2). Control animals (group 3) remained intact. There were no significant difference between total bilirubin, AsAT, glucose, creatinine, and total protein levels in blood plasma at different time-points after surgery. HDMPE turned out to have no appreciable effect on immunological characteristics and morphological features of the soft tissues lining tympanic bulla. It is concluded that HDMPE may serve as a material for the fabrication of prostheses of the auditory ossicle chain.

  16. Evaluation of the transfer of Listeria monocytogenes from stainless steel and high-density polyethylene to Bologna and American cheese.

    PubMed

    Rodríguez, Andrés; McLandsborough, Lynne A

    2007-03-01

    The objective of this study was to determine the factors involved in the transfer of Listeria monocytogenes from surfaces to foods. We evaluated the influence of surface type (stainless steel and high-density polyethylene), inoculation method (biofilm growth and attached cells), hydration level (visibly dry and wet), and food type (bologna and American cheese). Each experiment included all 16 combinations and was repeated 11 times. A four-strain cocktail of L. monocytogenes was used to inoculate stainless steel and high-density polyethylene either as growing biofilms or attached cells. Slides were placed on a universal testing machine and brought into contact with food at a constant pressure (45 kPa) and time (30 s). Food slices were blended, the number of transferred cells was determined by plating, and the efficiency of transfer (EOT) was calculated. The results strongly suggest that stainless steel surfaces transferred more L. monocytogenes to foods than did polyethylene (P = 0.05). Independent of the surface, biofilms tended to transfer more L. monocytogenes to foods (EOT = 0.57) than did attached cells (EOT = 0.16). Among foods, L. monocytogenes was transferred to bologna more easily than to cheese (P < 0.05). The impact of hydration on transfer was significantly higher for dried biofilms growing on stainless steel (P < 0.05). No significant differences for hydration were seen under other conditions (P > 0.05). We hypothesize that drying weakens cell-to-cell interactions in biofilms and cell-to-surface interactions of biofilms and thus allows increased transfer of cells to food products.

  17. Shear-horizontal surface acoustic wave phononic device with high density filling material for ultra-low power sensing applications

    SciTech Connect

    Richardson, M.; Bhethanabotla, V. R.; Sankaranarayanan, S. K. R. S.

    2014-06-23

    Finite element simulations of a phononic shear-horizontal surface acoustic wave (SAW) sensor based on ST 90°-X Quartz reveal a dramatic reduction in power consumption. The phononic sensor is realized by artificially structuring the delay path to form an acoustic meta-material comprised of a periodic microcavity array incorporating high-density materials such as tantalum or tungsten. Constructive interference of the scattered and secondary reflected waves at every microcavity interface leads to acoustic energy confinement in the high-density regions translating into reduced power loss. Tantalum filled cavities show the best performance while tungsten inclusions create a phononic bandgap. Based on our simulation results, SAW devices with tantalum filled microcavities were fabricated and shown to significantly decrease insertion loss. Our findings offer encouraging prospects for designing low power, highly sensitive portable biosensors.

  18. Surface optimization of high density polyethylene and carbon nanofiber composites for the improvement of electromagnetic shielding effectiveness

    NASA Astrophysics Data System (ADS)

    Jarvis, Brandon C.

    Nanoreinforced composites of High Density Polyethylene (HDPE) and Carbon Nanofibers (CNF) of varying nanofiber concentration were fabricated via melt mixing. Following fabrication, various metal and metal-nitride thin films were sputter deposited upon the substrates. Volume resistivity measurements of the composite substrates, as well as four point probe analysis of the composites and the deposited films were performed and are reported. Electromagnetic Interference (EMI) Shielding Effectiveness (SE) measurements were performed upon all samples in order to gauge the effects of percolation and the presence of the deposited film(s) upon overall SE. Comparisons of experimental measurements with analytical models available in the literature will be made in order to gain insight in to the dominant shielding mechanisms in the composite(s).

  19. Light-induced catalyst and solvent-free high pressure synthesis of high density polyethylene at ambient temperature.

    PubMed

    Ceppatelli, Matteo; Bini, Roberto

    2014-04-01

    The combined effect of high pressure and electronic photo-excitation has been proven to be very efficient in activating extremely selective polymerisations of small unsaturated hydrocarbons in diamond anvil cells (DAC). Here we report an ambient temperature, large volume synthesis of high density polyethylene based only on high pressure (0.4-0.5 GPa) and photo-excitation (~350 nm), without any solvent, catalyst or radical initiator. The reaction conditions are accessible to the current industrial technology and the laboratory scale pilot reactor can be scaled up to much larger dimensions for practical applications. FTIR and Raman spectroscopy, and X-ray diffraction, indicate that the synthesised material is of comparable quality with respect to the outstanding crystalline material obtained in the DAC. The polydispersity index is comparable to that of IV generation Ziegler-Natta catalysts. Moreover the crystalline quality of the synthesised material can be further enhanced by a thermal annealing at 373 K and ambient pressure.

  20. High-density polyethylene facial implants show surface oxidation in SEM and EDX examination: a pilot study.

    PubMed

    Draenert, G F; Doeblinger, M; Draenert, M; Gosau, M

    2009-05-01

    Previous histopathological studies on explanted Medpor high-density polyethylene (HDPE) facial implants indicated signs of material destruction and claimed to observe phagocytized HDPE particles within the tissue samples beside the usual type IV reaction with severe fibrosis. We examined new and explanted Medpor material with scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The implant surface of three patient-derived specimens showed significantly higher oxygenation in EDX analysis and morphological changes in SEM compared to the new unused material directly after opening of the package and after 1 year of exposure to air. Our preliminary findings indicate a possible oxidative biocorrosion in HDPE surgical implants. Further studies should confirm these pilot project results.

  1. Atomic force microscopic study of the structure of high-density polyethylene deformed in liquid medium by crazing mechanism.

    PubMed

    Bagrov, D V; Yarysheva, A Y; Rukhlya, E G; Yarysheva, L M; Volynskii, A L; Bakeev, N F

    2014-02-01

    A procedure has been developed for the direct atomic force microscopic (AFM) examination of the native structure of high-density polyethylene (HDPE) deformed in an adsorption-active liquid medium (AALM) by the crazing mechanism. The AFM investigation has been carried out in the presence of a liquid medium under conditions preventing deformed films from shrinkage. Deformation of HDPE in AALM has been shown to proceed through the delocalized crazing mechanism and result in the development of a fibrillar-porous structure. The structural parameters of the crazed polymer have been determined. The obtained AFM images demonstrate a nanosized nonuniformity of the deformation and enable one to observe the structural rearrangements that take place in the deformed polymer after removal of the liquid medium and stress relaxation. A structural similarity has been revealed between HDPE deformed in the AALM and hard elastic polymers.

  2. Radiation-Induced Grafting with One-Step Process of Waste Polyurethane onto High-Density Polyethylene.

    PubMed

    Park, Jong-Seok; Lim, Youn-Mook; Nho, Young-Chang

    2015-12-29

    The recycling of waste polyurethane (PU) using radiation-induced grafting was investigated. The grafting of waste PU onto a high-density polyethylene (HDPE) matrix was carried out using a radiation technique with maleic anhydride (MAH). HDPE pellets and PU powders were immersed in a MAH-acetone solution. Finally, the prepared mixtures were irradiated with an electron beam accelerator. The grafted composites were characterized by Fourier transformed infrared spectroscopy (FT-IR), surface morphology, and mechanical properties. To make a good composite, the improvement in compatibility between HDPE and PU is an important factor. Radiation-induced grafting increased interfacial adhesion between the PU domain and the HDPE matrix. When the absorbed dose was 75 kGy, the surface morphology of the irradiated PU/HDPE composite was nearly a smooth and single phase, and the elongation at break increased by approximately three times compared with that of non-irradiated PU/HDPE composite.

  3. Radiation-Induced Grafting with One-Step Process of Waste Polyurethane onto High-Density Polyethylene

    PubMed Central

    Park, Jong-Seok; Lim, Youn-Mook; Nho, Young-Chang

    2015-01-01

    The recycling of waste polyurethane (PU) using radiation-induced grafting was investigated. The grafting of waste PU onto a high-density polyethylene (HDPE) matrix was carried out using a radiation technique with maleic anhydride (MAH). HDPE pellets and PU powders were immersed in a MAH-acetone solution. Finally, the prepared mixtures were irradiated with an electron beam accelerator. The grafted composites were characterized by Fourier transformed infrared spectroscopy (FT-IR), surface morphology, and mechanical properties. To make a good composite, the improvement in compatibility between HDPE and PU is an important factor. Radiation-induced grafting increased interfacial adhesion between the PU domain and the HDPE matrix. When the absorbed dose was 75 kGy, the surface morphology of the irradiated PU/HDPE composite was nearly a smooth and single phase, and the elongation at break increased by approximately three times compared with that of non-irradiated PU/HDPE composite. PMID:28787813

  4. Preparation of a high-density polyethylene (HDPE) film with a nucleating agent during a stretching process

    NASA Astrophysics Data System (ADS)

    Park, Jong-Seok; Cho, In-Hee; Gwon, Sung-Jin; Lim, Youn-Mook; Nho, Young-Chang

    2009-07-01

    The effects of the crystallinity and a radiation crosslinking on the high-density polyethylene (HDPE) with a nucleating agent were investigated. We found the optimum conditions for the stretching process according to the addition of various quantities of a nucleating agent (Millad3988). The pores of a HDPE membrane were affected by the crystallinity of the polymer, and the crystallinity of the polymer was changed with an increase thermal ageing temperature. Thermal ageing treatment of the HDPE film was conducted in an oven at 110-135 °C for 5-60 min. When the conditions for the annealing were fixed at 125 °C and 40 min, we obtained the highest crystallinity. Also, the resulting mechanical properties of the irradiated HDPE separators were analyzed.

  5. Thermal, tensile and rheological properties of high density polyethylene (HDPE) processed and irradiated by gamma-ray in different atmospheres

    SciTech Connect

    Ferreto, H. F. R. E-mail: ana-feitoza@yahoo.com.br; Oliveira, A. C. F. E-mail: ana-feitoza@yahoo.com.br; Parra, D. F. E-mail: ablugao@ipen.br; Lugão, A. B. E-mail: ablugao@ipen.br; Gaia, R.

    2014-05-15

    The aim of this paper is to investigate structural changes of high density polyethylene (HDPE) modified by ionizing radiation (gamma rays) in different atmospheres. The gamma radiation process for modification of commercial polymers is a widely applied technique to promote new physical-chemical and mechanical properties. Gamma irradiation originates free radicals which can induce chain scission or recombination, providing its annihilation, branching or crosslinking. This polymer was irradiated with gamma source of {sup 60}Co at doses of 5, 10, 20, 50 or 100 kGy at a dose rate of 5 kGy/h. The changes in molecular structure of HDPE, after gamma irradiations were evaluated using thermogravimetric analysis (TGA) and tensile machine and oscillatory rheology. The results showed the variations of the properties depending on the dose at each atmosphere.

  6. A method for visualizing high-density porous polyethylene (medpor, porex) with computed tomographic scanning.

    PubMed

    Vendemia, Nicholas; Chao, Jerry; Ivanidze, Jana; Sanelli, Pina; Spinelli, Henry M

    2011-01-01

    Medpor (Porex Surgical, Inc, Newnan, GA) is composed of porous polyethylene and is commonly used in craniofacial reconstruction. When complications such as seroma or abscess formation arise, diagnostic modalities are limited because Medpor is radiolucent on conventional radiologic studies. This poses a problem in situations where imaging is necessary to distinguish the implant from surrounding tissues. To present a clinically useful method for imaging Medpor with conventional computed tomographic (CT) scanning. Eleven patients (12 total implants) who have undergone reconstructive surgery with Medpor were included in the study. A retrospective review of CT scans done between 1 and 16 months postoperatively was performed using 3 distinct CT window settings. Measurements of implant dimensions and Hounsfield units were recorded and qualitatively assessed. Of the 3 distinct window settings studied, namely, "bone" (W1100/L450), "soft tissue"; (W500/L50), and "implant" (W800/L200), the implant window proved the most ideal, allowing the investigators to visualize and evaluate Medpor in all cases. Qualitative analysis revealed that Medpor implants were able to be distinguished from surrounding tissue in both the implant and soft tissue windows, with a density falling between that of fat and fluid. In 1 case, Medpor could not be visualized in the soft tissue window, although it could be visualized in the implant window. Quantitative analysis demonstrated a mean (SD) density of -38.7 (7.4) Hounsfield units. Medpor may be optimally visualized on conventional CT scans using the implant window settings W800/L200, which can aid in imaging Medpor and diagnosing implant-related complications.

  7. Slow crack growth behavior in post-consumer recycled high-density polyethylene

    NASA Astrophysics Data System (ADS)

    Yang, Yuanjie

    A post-consumer recycled homopolymer (PCR-100-PE-N) was blended with high density ethylene hexene copolymer (HHM TR-480N) over the composition range of 0-100%. The resistance to slow crack growth (s.c.g.) was measured by a notched tensile test under a constant load in distilled water at three different temperatures 40sp°C, 60sp°C, and 80sp°C. The slow crack growth rate da/dt decreases about three or four orders at the same stress intensity factor and temperature as the composition increased from 0 to 100% of the copolymer. In the range of compositions below 50% of the copolymer, the slow crack growth rate decreases relatively slowly with composition compared to the very rapid decreases for compositions greater than 50% of the copolymer. The results might be explained in terms of a network formed by the crystals and the tie molecules that contain short-chain branches. The network becomes continuous when the copolymer is the major component and consequently the resistance to the slow crack growth increases rapidly. The fracture mechanisms for slow crack growth are identified using the activated rate process analysis. Considering the values of activation energies, it is concluded that progressive and incremental pull out of tie molecules from crystalline lamella was proposed as crack initiation mechanism. It is found from Ksb{c}-da/dt curve that crack propagates with a time dependence, average 0.224 ± 0.069, at low stress intensity, and a higher slopes, average 0.509 ± 0.099, at high stress intensity. With the help of SEM study of the fracture surfaces, it is concluded that average slope 0.224 represents sharp crack situation of relaxation, while the average slope 0.509 is considered to be the results of crack tip blunting effects.

  8. High-density polyethylene (HDPE)-degrading potential bacteria from marine ecosystem of Gulf of Mannar, India.

    PubMed

    Balasubramanian, V; Natarajan, K; Hemambika, B; Ramesh, N; Sumathi, C S; Kottaimuthu, R; Rajesh Kannan, V

    2010-08-01

    Assessment of high-density polyethylene (HDPE)-degrading bacteria isolated from plastic waste dumpsites of Gulf of Mannar. Rationally, 15 bacteria (GMB1-GMB15) were isolated by enrichment technique. GMB5 and GMB7 were selected for further studies based on their efficiency to degrade the HDPE and identified as Arthrobacter sp. and Pseudomonas sp., respectively. Assessed weight loss of HDPE after 30 days of incubation was nearly 12% for Arthrobacter sp. and 15% for Pseudomonas sp. The bacterial adhesion to hydrocarbon (BATH) assay showed that the cell surface hydrophobicity of Pseudomonas sp. was higher than Arthrobacter sp. Both fluorescein diacetate hydrolysis and protein content of the biofilm were used to test the viability and protein density of the biomass. Acute peak elevation was observed between 2 and 5 days of inoculation for both bacteria. Fourier transform infrared (FT-IR) spectrum showed that keto carbonyl bond index (KCBI), Ester carbonyl bond index (ECBI) and Vinyl bond index (VBI) were increased indicating changes in functional group(s) and/or side chain modification confirming the biodegradation. The results pose us to suggest that both Pseudomonas sp. and Arthrobacter sp. were proven efficient to degrade HDPE, albeit the former was more efficacious, yet the ability of latter cannot be neglected. Recent alarm on ecological threats to marine system is dumping plastic waste in the marine ecosystem and coastal arena by anthropogenic activity. In maintenance phase of the plastic-derived polyethylene waste, the microbial degradation plays a major role; the information accomplished in this work will be the initiating point for the degradation of polyethylene by indigenous bacterial population in the marine ecosystem and provides a novel eco-friendly solution in eco-management.

  9. Unexpected molecular weight dependence of shish-kebab structure in the oriented linear low density polyethylene/high density polyethylene blends.

    PubMed

    Liang, Si; Wang, Ke; Tang, Changyu; Zhang, Qin; Du, Rongni; Fu, Qiang

    2008-05-07

    In this study, highly oriented shish-kebab structure was achieved via imposing oscillatory shear on the melts of linear low density polyethylene (LLDPE)/high density polyethylene (HDPE) blends during the packing stage of injection molding. To investigate the effect of molecular weight of HDPE on the formation of shish-kebab structure, two kinds HDPE with large melt flow index (low molecular weight) and small melt flow index (high molecular weight) were added into LLDPE matrix. The structural characteristics of LLDPE/HDPE blends were systematically elucidated through two-dimensional wide-angle x-ray scattering, scanning electron microscopy, and differential scanning calorimetry. Interestingly, an unexpected molecular weight dependence of shish-kebab structure of the prepared samples was found that the addition of HDPE with low molecular weight resulted in an higher degree of orientation, better regularity of lamellar arrangement, thicker lamellar size, and higher crystal melting temperature than that adding HDPE with high molecular weight. Correspondingly, the blend containing low molecular weight HDPE had better tensile strength. A possible mechanism was suggested to elucidate the role of HDPE molecular weight on the formation of shish-kebab structure in the oriented blends, considering the change of chain mobility and entanglement density with change of molecular weight.

  10. In vitro evaluation of biocompatibility of beta-tricalcium phosphate-reinforced high-density polyethylene; an orthopedic composite.

    PubMed

    Homaeigohar, S Sh; Shokrgozar, M A; Sadi, A Yari; Khavandi, A; Javadpour, J; Hosseinalipour, M

    2005-10-01

    Beta-tricalcium phosphate-reinforced high-density polyethylene (beta-TCP/HDPE) is a new biomaterial which was made as a copy of bone composition with the aim of replacement of bony tissues. The composite samples were prepared using medical grade TCP powder and granular polyethylene. The raw materials were first compounded and the resulting composite preforms were compression molded into desired shape. The biocompatibility of composite samples with different volume fractions of TCP (20, 30, and 40 vol %) was assessed by proliferation, alkaline phosphatase (ALP), and cell adhesion assays using G-292 osteoblast cells. Cell-material interaction on the surface of the composites was observed by scanning electron microscopy (SEM). The effect of beta-TCP/HDPE on the behavior of G-292 cells was compared with those of a composite and a negative control samples. Results showed the composite samples had a higher proliferation rate of G-292 cells in the presence of composite samples as compared to the composite control sample after 3, 7, and 14 days of incubation period. ALP production after incubation in the presence of composite samples was seen to peak on the day 7. The number of adhered cells on the composite samples was higher than the numbers adhered on composite and negative control samples after the above incubation periods. Morphology investigation of adhered cells by SEM indicated a normal morphology and also many of the cells were in the process of cell division. The above results indicate that beta-TCP/HDPE samples are biocompatible, nontoxic, and in some cases show an increase in the proliferation rate of the cells, ALP production, and cell adhesion as compared to the control counterparts. (c) 2005 Wiley Periodicals, Inc.

  11. Ultraviolet weathering of photostabilized wood-flour-filled high-density polyethylene composites

    Treesearch

    Nicole M. Stark; Laurent M. Matuana

    2003-01-01

    Wood–plastic composites are being increasingly examined for nonstructural or semistructural building applications. As outdoor applications become more widespread, durability becomes an issue. Ultraviolet exposure can lead to photodegradation, which results in a change in appearance and/or mechanical properties. Photodegradation can be slowed through the addition of...

  12. Development of Functional Surfaces on High-Density Polyethylene (HDPE) via Gas-Assisted Etching (GAE) Using Focused Ion Beams.

    PubMed

    Sezen, Meltem; Bakan, Feray

    2015-12-01

    Irradiation damage, caused by the use of beams in electron and ion microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on electron/ion beam irradiation. Nevertheless, it is possible to turn degradation-dependent physical/chemical changes from negative to positive use when materials are intentionally exposed to beams. Especially, controllable surface modification allows tuning of surface properties for targeted purposes and thus provides the use of ultimate materials and their systems at the micro/nanoscale for creating functional surfaces. In this work, XeF2 and I2 gases were used in the focused ion beam scanning electron microscope instrument in combination with gallium ion etching of high-density polyethylene surfaces with different beam currents and accordingly different gas exposure times resulting at the same ion dose to optimize and develop new polymer surface properties and to create functional polymer surfaces. Alterations in the surface morphologies and surface chemistry due to gas-assisted etching-based nanostructuring with various processing parameters were tracked using high-resolution SEM imaging, complementary energy-dispersive spectroscopic analyses, and atomic force microscopic investigations.

  13. Influence of triallyl cyanurate as co-agent on gamma irradiation cured high density polyethylene/reclaimed tire rubber blend

    NASA Astrophysics Data System (ADS)

    Mali, Manoj N.; Arakh, Amar A.; Dubey, K. A.; Mhaske, S. T.

    2017-02-01

    Utilization of waste from tire industry as reclaimed tire rubber (RTR) by formation of blends with high density polyethylene (HDPE) is great area to be focused. Enhancement of properties by the addition of triallyl cyanurate (TAC) as a co-agent with 1%, 3% and 5% to blend of HDPE 50 wt% and RTR 50 wt% in presence of gamma irradiation curing were investigated. Specifically, mechanical and thermal properties were studied as a function of amount of TAC and gamma irradiation dose in range of 50-200 kGy. The resultant blends were evaluated for the values of impact strength, gel content, thermal stability, tensile properties, rheological properties and morphological properties with increasing irradiation dosage and TAC loading. The mechanical properties tensile strength, hardness, impact strength of blend containing 3% of TAC were substantially increased with increasing irradiation dosage up to 150 KGy. Rheological analysis has shown increase in viscosity with increase in TAC loading up to 3% and 150 KGy irradiation dosages. 3% loading of TAC lead to better set of properties with150 KGy gamma irradiation dosage.

  14. A high-density poly(ethylene glycol) polymer brush for immobilization on glass-type surfaces.

    PubMed

    Piehler, J; Brecht, A; Valiokas, R; Liedberg, B; Gauglitz, G

    2000-01-01

    Label-free heterogeneous phase detection critically depends on the properties of the interfacial layer. We have obtained high-density monomolecular poly(ethylene glycol) (PEG) layers by solvent-free coupling of homo-bifunctional PEGs (2,000 g/mol) at 75 degrees C to silica surfaces silanized with glycidyloxipropyltrimethoxysilane (GOPTS). Characterization by ellipsometry and contact angles revealed that PEG layers up to 3.4 ng/mm2 with low roughness and flexibility were obtained. Specific and non-specific binding at these PEG surfaces was monitored by reflectometric interference spectroscopy (RIfS). No significant non-specific adsorption upon incubation of 1 mg/ml ovalbumin was detectable (< 10 pg/mm2), and 150 pg/mm2 upon incubation of 10% calf serum, less than 10% of the amount adsorbed to the solely silanized surfaces. The terminal functional groups of the PEG layers were utilized to couple ligands and a protein. Specific protein interaction with these immobilized compounds was detected with saturation loadings in the range of protein monolayers (2-4 ng/mm2). The excellent functional properties, the high stability of the layers, the generic and practical coupling procedure and the versatility for immobilizing compounds of very different functionality make these PEG layers very attractive for application in label-free detection with silica or metal-oxide based transducers.

  15. Achromobacter xylosoxidans as a new microorganism strain colonizing high-density polyethylene as a key step to its biodegradation.

    PubMed

    Kowalczyk, Anna; Chyc, Marek; Ryszka, Przemysław; Latowski, Dariusz

    2016-06-01

    This study presents results of research on isolation new bacteria strain Achromobacter xylosoxidans able to effect on the structure of high-density polyethylene (HDPE), polymer resistant to degradation in environment. New strain of A. xylosoxidans PE-1 was isolated from the soil and identified by analysis of the 16S ribosome subunit coding sequences. The substance to be degraded was HDPE in the form of thin foil films. The foil samples were analyzed with Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR) as well as scanning electron microscope (SEM), and the results revealed degradation of chemical structure of HDPE. About 9 % loss of weight was also detected as a result of A. xylosoxidans PE-1 effect on HDPE foil. On the basis of comparative spectral analysis of the raw material before the bacteria treatment and the spectrum from a spectra database, it was assumed that the HDPE was the only source of carbon and energy for the microorganisms. No fillers or other additives used in the plastic processing were observed in HDPE before experiments. This is the first communication showing that A. xylosoxidans is able to modify chemical structure of HDPE, what was observed both on FTIR, in mass reduction of HDPE and SEM analysis. We also observed quite good growth of the bacteria also when the HDPE was the sole carbon source in the medium. These results prove that A. xylosoxidans is an organism worth applying in future HDPE biodegradation studies.

  16. Thermal and mechanical properties of e-beam irradiated butt-fusion joint in high-density polyethylene pipes

    NASA Astrophysics Data System (ADS)

    Vijayan, Vipin; Pokharel, Pashupati; Kang, Min Kwan; Choi, Sunwoong

    2016-05-01

    The effects of electron beam irradiation on the thermal and mechanical properties of a butt-fusion joint in high density polyethylene (HDPE) pipes were investigated. Differential scanning calorimetry, X-ray diffraction, and Fourier transform infra-red spectroscopy of welded samples revealed the changes of crystallinity due to the cross linking effect of electron beam irradiation. The suppression of the degree of crystallinity with increasing the irradiation dose from 0 kGy to 500 kGy indicated that the e-beam radiation induced cross-links among the polymer chains at the weld zone. The cross-link junction at the joint of HDPE pipe prevented chain folding and reorganization leading to the formation of imperfect crystallites with smaller size and also less in content. Tensile test of the welded samples with different dose of e-beam irradiation showed the increased values of the yield stress and Young's modulus as a function of irradiation dose. On the other hand, the elongation at break diminished clearly with increasing the irradiation doses.

  17. From macroplastic to microplastic: Degradation of high-density polyethylene, polypropylene, and polystyrene in a salt marsh habitat.

    PubMed

    Weinstein, John E; Crocker, Brittany K; Gray, Austin D

    2016-07-01

    As part of the degradation process, it is believed that most plastic debris becomes brittle over time, fragmenting into progressively smaller particles. The smallest of these particles, known as microplastics, have been receiving increased attention because of the hazards they present to wildlife. To understand the process of plastic degradation in an intertidal salt marsh habitat, strips (15.2 cm × 2.5 cm) of high-density polyethylene, polypropylene, and extruded polystyrene were field-deployed in June 2014 and monitored for biological succession, weight, surface area, ultraviolet (UV) transmittance, and fragmentation. Subsets of strips were collected after 4 wk, 8 wk, 16 wk, and 32 wk. After 4 wk, biofilm had developed on all 3 polymers with evidence of grazing periwinkles (Littoraria irrorata). The accreting biofilm resulted in an increased weight of the polypropylene and polystyrene strips at 32 wk by 33.5% and 167.0%, respectively, with a concomitant decrease in UV transmittance by approximately 99%. Beginning at 8 wk, microplastic fragments and fibers were produced from strips of all 3 polymers, and scanning electron microscopy revealed surface erosion of the strips characterized by extensive cracking and pitting. The results suggest that the degradation of plastic debris proceeds relatively quickly in salt marshes and that surface delamination is the primary mechanism by which microplastic particles are produced in the early stages of degradation. Environ Toxicol Chem 2016;35:1632-1640. © 2016 SETAC.

  18. Clinical field follow-up of high density polyethylene (HDPE)-Jaipur prosthetic technology for trans-tibial amputees.

    PubMed

    Jensen, J S; Craig, J G; Mtalo, L B; Zelaya, C M

    2004-12-01

    The purpose of this study was to examine the outcome of the application of the High Density Polyethylene (HDPE)-Jaipur prosthetic construction in fitting trans-tibial amputees in a number of projects in the developing world. Projects in Honduras, Uganda and India were visited. Three hundred and twenty (320) patients had been provided with a HDPE-Jaipur prosthesis and of these 172 were seen for a technical and clinical follow-up after a median of 35 months. More than half the amputations were due to trauma, the remainder to disease. Fabrication and fitting in the three projects was carried out by individuals who had undertaken a twice week training course provided by Bhagwan Mahaveer Viklang Sahayata Samiti limb centre in Jaipur. The individuals involved had limited background training in prosthetics. Craftsmanship and fit were assessed as being poor in 56% of cases. The technical quality of the Jaipur foot was considered acceptable as its performance was better than previously observed results. Although there was patient satisfaction of 85% and compliance of 94% the HDPE-Jaipur trans-tibial system was not considered acceptable as 49% reported walking distances less than 1km and 36% discomfort. The major inadequacy in outcome relates to the use for fabrication and fitting of individuals with inadequate education and training.

  19. Clinical field follow-up of high density polyethylene (HDPE)-Jaipur prosthetic technology for trans-femoral amputees.

    PubMed

    Jensen, J S; Craig, J G; Mtalo, L B; Zelaya, C M

    2004-08-01

    The purpose of this study was to examine the outcome of the application of the high density polyethylene (HDPE)-Jaipur prosthetic construction in fitting trans-femoral amputees in a number of projects throughout the developing world. Projects in Honduras, Uganda and India were included. One hundred and fifty eight (158) patients had been provided with the HDPE-Jaipur prosthesis and of these 72 were seen for a clinical and technical follow-up after a median of 32 months. More than half the amputees seen had amputation due to trauma and the remainder due to disease. Fabrication and fitting in the three projects was carried out by individuals who had undertaken a three week training course provided by Bhagwan Mahaveer Viklang Sahayata Samiti limb centre in Jaipur. The individuals involved had limited background training in prosthetics. Craftsmanship and fit were assessed as being poor in 86% of cases. Failure requiring replacement of components was observed in 50% of cases. There was low patient satisfaction (58%) and patient compliance (65%). The outcome was considered unsatisfactory both technically and clinically. This was a reflection of the inadequacies of the prosthetic construction, particularly the knee joint, and the inadequate training of those involved in fitting and fabrication of the devices.

  20. Engineering cartilage substitute with a specific size and shape using porous high-density polyethylene (HDPE) as internal support.

    PubMed

    Wu, Yujia; Zhu, Lie; Jiang, Hua; Liu, Wei; Liu, Yu; Cao, Yilin; Zhou, Guangdong

    2010-04-01

    Despite the great advances in cartilage engineering, constructing cartilage of large sizes and appropriate shapes remains a great challenge, owing to limits in thickness of regenerated cartilage and to inferior mechanical properties of scaffolds. This study introduces a pre-shaped polyglycolic acid (PGA)-coated porous high-density polyethylene (HDPE) scaffold to overcome these challenges. HDPE was carved into cylindrical rods and wrapped around by PGA fibres to form PGA-HDPE scaffolds. Porcine chondrocytes were seeded into the scaffolds and the constructs were cultured in vitro for 2 weeks before subcutaneous implantation into nude mice. Scaffolds made purely of PGA with the same size and shape were used as a control. After 8 weeks of implantation, the construct formed cartilage-like tissue and retained its pre-designed shape and size. In addition, the regenerated cartilage grew and completely surrounded the HDPE core, which made the entire cartilage substitute biocompatible to its implanted environment as native cartilage similarly does. By contrast, the shape and size of the constructs in the control group seriously deformed and obvious hollow cavity and necrotic tissue were observed in the inner region. These results demonstrate that the use of HDPE as the internal support of a biodegradable scaffold has the potential to circumvent the problems of limitations in size and shape, with promising implications for the development of engineered cartilage appropriate for clinical applications. Copyright 2009 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

  1. Effective thermal conductivity and coefficient of linear thermal expansion of high-density polyethylene — fly ash composites

    NASA Astrophysics Data System (ADS)

    Baglari, Sanjib; Kole, Madhusree; Dey, T. K.

    2011-04-01

    As the disposal of fly ash (FA) poses a serious problem in terms of land use and potential environmental pollution, there exists a global interest for its utilization. Utilization of fly ash as filler material in polymer composites is considered important from both economic and commercial point of view. In this communication, the effective thermal conductivity and coefficient of thermal expansion (CTE) of composites synthesized with fly ash filler embedded in high-density polyethylene (HDPE) matrix is investigated. Incorporation of fly ash in HDPE enhances both the thermal stability and the effective thermal conductivity of the composites. CTE, however, significantly decreases as the FA content increases in HDPE. Effective thermal conductivity for HDPE containing 70-volume fraction (%) fly ash becomes almost twice than that for unfilled HDPE. Results on both the effective thermal conductivity and CTE of HDPE/FA composites have been discussed in light of various theoretical models. Our analysis indicates formation of conductive channels of FA particulates in HDPE, which causes rapid enhancement in the effective thermal conductivity of the HDPE/FA composites. We also confirm the importance of the role of the interphase volume and the strength of the polymer — filler interactions to successfully predict the CTE of HDPE/FA composites.

  2. High-Density Polyethylene (HDPE) Surface Treatment Using an RF Capacitive Atmospheric Pressure Cold Ar Plasma Jet

    NASA Astrophysics Data System (ADS)

    Fei, Xiaomeng; Shin-ichi, Kuroda; Tamio, Mori; Katsuhiko, Hosoi

    2013-06-01

    In this study, a high-density polyethylene (HDPE, 5-mm-thick, 0.95 g/cm3) surface was treated using an RF capacitive atmospheric pressure cold Ar plasma jet. By using this Ar plasma jet, a hydrophilic HDPE surface was formed during the plasma treatment. In particular, the effects of an additive gas (N2 or O2) on the HDPE surface treatment were investigated in detail. It was shown that the addition of N2 or O2 gas had an important influence on the HDPE surface treatment. Compared to pure Ar plasma treatment, a lower value of water contact angle (WCA) was obtained when a trace of N2 or O2 gas was added. It was also found that besides the quantities of active species in the plasma jet, the treatment temperature played an important role in the HDPE surface treatment. This is because surface molecular motion is not negligible when the treatment temperature is close to the melting point of the polymer.

  3. Fast co-pyrolysis of waste newspaper with high-density polyethylene for high yields of alcohols and hydrocarbons.

    PubMed

    Chen, Weimin; Shi, Shukai; Chen, Minzhi; Zhou, Xiaoyan

    2017-09-01

    Waste newspaper (WP) was first co-pyrolyzed with high-density polyethylene (HDPE) using pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) to enhance the yields of alcohols and hydrocarbons. The effects of WP: HDPE feed ratio (100:0, 75:25, 50:50, 25:75, 0:100) and temperature (500-800°C) on products distribution were investigated and the interaction mechanism during co-pyrolysis was also proposed. Maximum yields of alcohols and hydrocarbons reached 85.88% (feed ratio 50:50wt.%, 600°C). Hydrogen supplements and deoxidation by HDPE and subsequently fragments recombination result in the conversion of aldehydes and ketones into branched hydrocarbons. Radicals from WP degradation favor the secondary crack for HDPE products resulting in the formation of linear hydrocarbons with low carbon number. Hydrocarbons with activated radical site from HDPE degradation were interacted with hydroxyl from WP degradation promoting the formation of linear long chain alcohols. Moreover, co-pyrolysis significantly enhanced condensable oil qualities, which were close to commercial diesel No. 0. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Enhanced diesel fuel fraction from waste high-density polyethylene and heavy gas oil pyrolysis using factorial design methodology.

    PubMed

    Joppert, Ney; da Silva, Alexsandro Araujo; da Costa Marques, Mônica Regina

    2015-02-01

    Factorial Design Methodology (FDM) was developed to enhance diesel fuel fraction (C9-C23) from waste high-density polyethylene (HDPE) and Heavy Gas Oil (HGO) through co-pyrolysis. FDM was used for optimization of the following reaction parameters: temperature, catalyst and HDPE amounts. The HGO amount was constant (2.00 g) in all experiments. The model optimum conditions were determined to be temperature of 550 °C, HDPE = 0.20 g and no FCC catalyst. Under such conditions, 94% of pyrolytic oil was recovered, of which diesel fuel fraction was 93% (87% diesel fuel fraction yield), no residue was produced and 6% of noncondensable gaseous/volatile fraction was obtained. Seeking to reduce the cost due to high process temperatures, the impact of using higher catalyst content (25%) with a lower temperature (500 °C) was investigated. Under these conditions, 88% of pyrolytic oil was recovered (diesel fuel fraction yield was also 87%) as well as 12% of the noncondensable gaseous/volatile fraction. No waste was produced in these conditions, being an environmentally friendly approach for recycling the waste plastic. This paper demonstrated the usefulness of using FDM to predict and to optimize diesel fuel fraction yield with a great reduction in the number of experiments.

  5. Parameterization of an interfacial force field for accurate representation of peptide adsorption free energy on high-density polyethylene

    PubMed Central

    Abramyan, Tigran M.; Snyder, James A.; Yancey, Jeremy A.; Thyparambil, Aby A.; Wei, Yang; Stuart, Steven J.; Latour, Robert A.

    2015-01-01

    Interfacial force field (IFF) parameters for use with the CHARMM force field have been developed for interactions between peptides and high-density polyethylene (HDPE). Parameterization of the IFF was performed to achieve agreement between experimental and calculated adsorption free energies of small TGTG–X–GTGT host–guest peptides (T = threonine, G = glycine, and X = variable amino-acid residue) on HDPE, with ±0.5 kcal/mol agreement. This IFF parameter set consists of tuned nonbonded parameters (i.e., partial charges and Lennard–Jones parameters) for use with an in-house-modified CHARMM molecular dynamic program that enables the use of an independent set of force field parameters to control molecular behavior at a solid–liquid interface. The R correlation coefficient between the simulated and experimental peptide adsorption free energies increased from 0.00 for the standard CHARMM force field parameters to 0.88 for the tuned IFF parameters. Subsequent studies are planned to apply the tuned IFF parameter set for the simulation of protein adsorption behavior on an HDPE surface for comparison with experimental values of adsorbed protein orientation and conformation. PMID:25818122

  6. Reinforcement of natural rubber/high density polyethylene blends with electron beam irradiated liquid natural rubber-coated rice husk

    NASA Astrophysics Data System (ADS)

    Chong, E. L.; Ahmad, Ishak; Dahlan, H. M.; Abdullah, Ibrahim

    2010-08-01

    Coating of rice husk (RH) surface with liquid natural rubber (LNR) and exposure to electron beam irradiation in air were studied. FTIR analysis on the LNR-coated RH (RHR) exposed to electron beam (EB) showed a decrease in the double bonds and an increase in hydroxyl and hydrogen bonded carbonyl groups arising from the chemical interaction between the active groups on RH surface with LNR. The scanning electron micrograph showed that the LNR formed a coating on the RH particles which transformed to a fine and clear fibrous layer at 20 kGy irradiation. The LNR film appeared as patches at 50 kGy irradiation due to degradation of rubber. Composites of natural rubber (NR)/high density polyethylene (HDPE)/RHR showed an optimum at 20-30 kGy dosage with the maximum stress, tensile modulus and impact strength of 6.5, 79 and 13.2 kJ/m 2, respectively. The interfacial interaction between the modified RH and TPNR matrix had improved on exposure of RHR to e-beam at 20-30 kGy dosage.

  7. Incorporation of Copper Enhances the Anti-Ageing Property of Flame-Sprayed High-Density Polyethylene Coatings

    NASA Astrophysics Data System (ADS)

    Jia, Zhengmei; Huang, Jing; Gong, Yongfeng; Jin, Peipeng; Suo, Xinkun; Li, Hua

    2017-02-01

    High-density polyethylene (HDPE)-copper (Cu) composite coatings were prepared through depositing HDPE-Cu core-shell particles by flame spraying. The HDPE-Cu composite coatings and the HDPE coatings were aged in xenon lamp ageing testing chamber. The variations of chemical compositions and surface morphology of the coatings before and after the ageing testing were analyzed using infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and ultraviolet-visible spectrophotometer. Results show that there is no chemical composition variation in the HDPE-Cu coatings. Cracks were found on the surfaces of the HDPE coatings, while the HDPE-Cu coating shows almost intact surface morphology. These results suggest that the HDPE-Cu coatings present better anti-ageing performances than the HDPE coatings. Further assessment of the function of Cu shells on the anti-ageing property reveals that Cu shells not only enhanced the absorption of the coatings to ultraviolet, but also increased their reflectivity to visible light. Additionally, the Cu shells enhanced the decomposition temperature and thermal stability of HDPE in the composite coatings. These results give bright insight into potential anti-ageing applications of the polymer-based structures.

  8. Influence of γ-ray modified MWCNTs on the structural and thermal properties of high-density polyethylene

    NASA Astrophysics Data System (ADS)

    Ghafoor, Bilal; Mehmood, Malik Sajjad; Shahid, Umair; Baluch, Mansoor A.; Yasin, Tariq

    2016-08-01

    This study aims to investigate the influence of adding 100 kGy γ-irradiated multi wall carbon nano tubes (MWCNTs) on the structural and thermal properties of high-density polyethylene (HDPE). The effects of further γ-irradiation in the presence of γ-MWCNTs on aforementioned properties have also been investigated. FTIR spectroscopic measurements of HDPE and HDPE/γ-MWCNTs composites reveal that modification of MWCNTs with ≤100 kGy of γ-dose reduces its efficiency as free radical quencher. This behavior is found to increase further with the increase in the concentration of γ-MWCNTs. Wide angle X-ray diffraction (WAXD) data shows a decrease in percent crystallinity and shifting of crystalline peaks toward lower values of 2θ angles. This behavior is mainly attributed to the oxidation induced due to residual free radicals. Thermal analysis reveals that addition of γ-MWCNTs decreases the thermal stability as far as onset thermal degradation temperature, percent crystallinity, and melting temperature of UHMWPE/γ-MWCNTs. In addition to this, gel content measurements show that insoluble percentage of UHMWPE is higher with the incorporation γ-MWCNTs and further irradiation. The gel contents are found to improve up to 29% and 60%, respectively with the incorporation of γ-MWCNTs and further irradiation.

  9. Novel cholesterol feeding strategy enables a high-density cultivation of cholesterol-dependent NS0 cells in linear low-density polyethylene-based disposable bioreactors.

    PubMed

    Tao, Yiwen; Yusuf-Makagiansar, Helena; Shih, Jennifer; Ryll, Thomas; Sinacore, Marty

    2012-08-01

    We have developed a perfusion-based high cell density (HD) cell banking and inoculum expansion procedure for a cholesterol-dependent NS0 myeloma cell line using linear low-density polyethylene-based disposable bioreactors. Challenges associated with cholesterol-polymer interactions, which suppress cholesterol-dependent NS0 myeloma cell growth, were overcome using a novel cholesterol feeding protocol that included a combination of two cholesterol formulations: an ethanol-based formulation and an aqueous formulation. Using a cholesterol feed optimized for HD cell culture in a disposable bioreactor perfusion system, cell densities of >25 × 10(6) viable cells/ml at ≥ 90 % cell viability were achieved. Vials of high density cell banks were created by filling 90-100 × 10(6) viable cells/ml in 5 ml cryotube vials. Implementation of the HD cell banks enabled a significant reduction in the number of step operations in the inoculum expansion phase in a large-scale manufacturing setting.

  10. High density polyethylene (HDPE)/poly(ethylene terephthalate) (PET) polymer blend studies related to recycling co-mingled plastics

    NASA Astrophysics Data System (ADS)

    Tsai, Pang-Yen

    Polymer blends of virgin high density polyethylene (HDPE) and poly(ethylene terephthalate) (PET) were studied as an attempt to relate the microstructure to the mechanical properties of the blends. The virgin blends were prepared by extrusion and then injection molded into specimens for characterization. Two of the virgin blends were tested for possible compatibilization using a styrene-ethylene-butylene-styrene (SEBS) block copolymer. In addition, six blends of post-consumer resins (PCRs) of HDPE and PET were included in this work for comparison. The moduli of the virgin blends showed positive deviation from those expected from the rule of mixtures. The synergism of the composite moduli can be explained partly by a Poisson's effect. Yield strengths of the blends molded at low injection chamber temperatures (200sp°, 230sp°, and 250sp°C) followed the rule of mixtures well, because PET filaments found in the composites had very high length to diameter ratios. When the injection chamber temperature was above the PET melting point (˜254sp°C), PET filaments were found to break down into particles, and the yield strengths of the blends coincided with the values expected from the inverse rule of mixtures. Impact strengths of the virgin blends were much less than that of a HDPE homopolymer due to poor interfacial bonding between HDPE and PET. Compatibilization appeared to be advantageous since it dramatically improved the impact strength of the virgin blends. SEM micrographs of impact fractured surfaces revealed that the improved adhesion from compatibilization and the presence of numerous uniaxially aligned PET filaments in the HDPE substrate can account for the significant increases in fracture resistance of the compatibilized blends. Mechanical performance of the PCRs was inferior to that of the virgin blends. Aside from polymer degradation and contamination due to repeated processing and handling, absence of PET filaments and interfacial bonding could be

  11. Determination of the effect of exposure to gasoline components on a high density polyethylene geomembrane using the comprehensive test system.

    PubMed

    Barrett, W M; Stessel, R I

    1999-05-31

    The comprehensive testing system (CTS) for geomembranes was used to test the compatibility of high-density polyethylene (HDPE) geomembrane landfill liner material with chemicals typically found in motor vehicle fuel. The CTS is a testing apparatus specifically designed to test the effects of simultaneously applying mechanical load, fluid head, and chemical exposure on the geomembrane. A combination of these factors is present on the geomembrane material in service, and the CTS provides a laboratory reproduction of actual field conditions. The article provides a description of gasoline based upon the desirable qualities of gasoline and provides background on testing of rubbers used in gasoline-powered engine parts. The test's chemicals were gasoline, motor oil, benzene, ethylbenzene, toluene, xylenes, and iso-octane (2,2,4 trimethyl pentane). This work found that gasoline had an effect on the geomembrane greater than the effect of any of the pure chemicals except ethylbenzene. Benzene, and the other aromatic compounds (ethylbenzene, toluene, and xylenes) are typically the primary regulatory concerns at fuel contaminated sites. The fact that gasoline had a greater effect on the performance of the HDPE geomembrane indicated that chemicals are present in gasoline which can decrease the performance of the containment structures used to hold gasoline, while not having a significant health risk. The clear implication is that risk assessments conducted on facilities must not only include the health risks of chemicals placed in a facility, but must also consider the effect of the chemical on a containment structure. The fact that low-health-risk chemicals may have a great impact on the effectiveness of containment structures leads to a possible synergistic mechanism where the low-health-risk chemicals enable a pathway for greater-health-risk chemicals to enter the environment. Copyright 1999 Elsevier Science B.V.

  12. High density polyethylene/graphite nano-composites for total hip joint replacements: processing and in vitro characterization.

    PubMed

    Fouad, H; Elleithy, Rabeh

    2011-10-01

    The main objective of the present study is to investigate how the thermal, rheological, mechanical and cytotoxicity behavior of High Density Polyethylene (HDPE) can be changed by the addition of graphite nano particles (GNPs) at different contents. The HDPE/GNPs composites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The in vitro tests results showed that the original material (HDPE) and all HDPE/GNPs composites do not exhibit any cytotoxicity to the WISH cell line. The microscopic examination of the nano-composite tensile-fractured surface found a good distribution of GNPs in the HDPE matrix. The Differential Scanning Calorimetry (DSC) results indicated that the crystallization percentage increased by adding GNPs to HDPE up to 4%. The XRD patterns of the HDPE/GNPs composites showed an increase in peak intensity compared to neat HDPE. This increase echoed the crystallinity results obtained from DSC. The rheological tests showed that the complex viscosity of the HDPE increased as the percentage of GNPs increased due to the restriction of the molecular mobility. The tensile test results showed that with increasing the GNPs content, Young's modulus and the yield strength of the HDPE/GNPs composite increased while the strain at fracture decreased. Finally, the preliminary results of the abrasion test indicated that the abrasion rate decreased by increasing the GNPs ratio up to 4% content. The prepared HDPE/GNPs composites appear to have fairly good comprehensive properties that make them a good candidate as a bearing material for the total joint replacement. Copyright © 2011 Elsevier Ltd. All rights reserved.

  13. Structure development during isothermal crystallisation of high-density polyethylene: Synchrotron small-angle X-ray scattering study

    NASA Astrophysics Data System (ADS)

    Ślusarczyk, Czesław

    2013-12-01

    Isothermal melt crystallisation in high-density polyethylene (HDPE) was studied using the time-resolved SAXS method with synchrotron radiation over a wide range of crystallisation temperatures. The SAXS profile was analysed by an interface distribution function, g1(r), which is a superposition of three contributions associated with the size distributions of crystalline (LC) and amorphous (LA) layers and a distribution of long period (LP). The morphological parameters extracted from the g1(r) functions show that the lamellar thickness increases with time, obeying a logarithmic time dependence. The time evolution of LC observed for the sample crystallised at 122 °C leads to the conclusion that crystallisation proceeds according to the mechanism of thickening growth. For samples crystallised at lower temperatures (116 °C and 118 °C), the lamellar thickening mechanism has been observed. The rate of lamellar thickening in these cases is much lower than that at 122 °C. At 40 °C, thickening of the crystalline layer does not occur. The interface distribution functions were deconvoluted, and the relative standard deviation σC/LC obtained in this way is an additional parameter that is varied during crystallisation and can be used for analysis of this process. Time-dependent changes in the σC/LC at large supercooling (TC=40 °C) indicates that LC presents a broad distribution in which the relative standard deviation increases with time. At lower supercooling (TC=122 °C), LC shows a much sharper distribution. In this case, the relative standard deviation decreases with time.

  14. Effect of admixed high-density polyethylene (HDPE) spheres on contraction stress and properties of experimental composites.

    PubMed

    Ferracane, J L; Ferracane, L L; Braga, R R

    2003-07-15

    Additives that provide stress relief may be incorporated into dental composites to reduce contraction stress (CS). This study attempted to test the hypothesis that conventional fillers could be replaced by high-density polyethylene (HDPE) spheres in hybrid and nanofill composites to reduce CS, but with minimal effect on mechanical properties. Nanofill and hybrid composites were made from a Bis-GMA/TEGDMA resin having either all silica nanofiller or 75 wt.% strontium glass + 5 wt.% silica and replacing some of the nanofiller or the glass with 0%, 5% (hybrid only), 10% or 20 wt.% HDPE. The surface of the HDPE was either left untreated or had a reactive gas surface treatment (RGST). Contraction stress (CS) was monitored for 10 min in a tensilometer (n = 5) after light curing for 60 s at 390 mW/cm(2). Other specimens (n = 5) were light cured 40 s from two sides in a light-curing unit and aged 1 d in water before testing fracture toughness (K(Ic)), flexure strength (FS), and modulus (E). Results were analyzed by ANOVA with Tukey's multiple comparison test at p < 0.05. There was no difference between composites with RGST and untreated HDPE except for FS-10% HDPE hybrid (RGST higher). An increased level of HDPE reduced contraction stress for both types of composites. Flexure strength, modulus (hybrid only), and fracture toughness were also reduced as the concentration of HDPE increased. SEM showed evidence for HDPE debonding and plastic deformation during fracture of the hybrid composites. In conclusion, the addition of HDPE spheres reduces contraction stress in composites, either through stress relief or a reduction in elastic modulus. Copyright 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 66B: 318-323, 2003

  15. Methyl bromide emission from fields partially covered with a high-density polyethylene and a virtually impermeable film

    SciTech Connect

    Wang, D.; Yates, S.R.

    1998-09-01

    Recent field studies in the interior valley of southern California have indicated that 56--73% of methyl bromide (MeBr) used in soil fumigation is lost to atmospheric emission when the fields are covered completely with a high-density polyethylene (HDPE) film. The emission can be reduced to less than 5% when a virtually impermeable film or Hytibar is used to cover the fields. This study was conducted to determine MeBr emission from bedded field plots where only the beds were covered with a HDPE or a virtually impermeable plastic film. The results provide an assessment on MeBr emission from field beds partially covered with the HDPE film and the suitability of using a virtually impermeable film for emission reduction. Methyl bromide gas was applied to replicated field beds covered with either a HDPE or the Hytibar film. The films were removed 6 days after MeBr application. Replicated soil cores were taken from different locations of the field beds, 20 days after MeBr application, for the determination of soil bromide ion concentrations. The total amount of MeBr degraded from each plot was calculated from the measured bromide ion concentrations, and the potential emission was determined as the difference between the amount of applied and that of degraded. Results indicated that the potential emission from this bedded system was about 95% for the HDPE treatment and 90% for the Hytibar-covered plots. Regardless of the small improvement with the virtually impermeable film, the experiment clearly indicates that partially covering the field with either a HDPE or a virtually impermeable film would result in unacceptably high emission losses.

  16. Extrapolation of creep behavior of high-density polyethylene liner in the Catch Basin of grout vaults

    SciTech Connect

    Whyatt, G.A.

    1995-07-01

    Testing was performed to determine if gravel particles will creep into and puncture the high-density polyethylene (HDPE) liner in the catch basin of a grout vault over a nominal 30-year period. Testing was performed to support a design without a protective geotextile cover after the geotextile was removed from the design. Recently, a protective geotextile cover over the liner was put back into the design. The data indicate that the geotextile has an insignificant effect on the creep of gravel into the liner. However, the geotextile may help to protect the liner during construction. Two types of tests were performed to evaluate the potential for creep-related puncture. In the first type of test, a very sensitive instrument measured the rate at which a probe crept into HDPE over a 20-minute period at temperatures of 176{degrees}F to 212{degrees}F (80{degrees}C to 100{degrees}C). The second type of test consisted of placing the liner between gravel and mortar at 194{degrees}F (90{degrees}C) and 45.1 psi overburden pressure for periods up to 1 year. By combining data from the two tests, the long-term behavior of the creep was extrapolated to 30 years of service. After 30 years of service, the liner will be in a nearly steady condition and further creep will be extremely small. The results indicate that the creep of gravel into the liner will not create a puncture during service at 194{degrees}F (90{degrees}C). The estimated creep over 30 years is expected to be less than 25 mils out of the total initial thickness of 60 mils. The test temperature of 194{degrees}F (90{degrees}C) corresponds to the design basis temperature of the vault. Lower temperatures are expected at the liner, which makes the test conservative. Only the potential for failure of the liner resulting from creep of gravel is addressed in this report.

  17. Long-term results of high-density porous polyethylene implants in facial skeletal augmentation: An Indian perspective

    PubMed Central

    Deshpande, Sanjeev; Munoli, Amarnath

    2010-01-01

    Context: With the increasing emphasis on well-sculpted facial features, today there is a growing need for tools to augment the facial skeleton; either for cosmetic reasons or to re-contour deformities-congenital, post-traumatic and post-ablative. The limitations of autogenous materials has lead to evolution of numerous 'alloplasts', of which, high-density porous polyethylene (HDPE) seems to be a promising alternative. Aims: To evaluate the long term results of HDPE in facial skeletal augmentation in terms of achieving desired facial contour, patient satisfaction and complications. Settings: A tertiary care referral centre in a metropolitan set-up. Design: Case Series Materials and Methods: All patients undergoing HDPE implant insertion for facial skeletal augmentation between July 2001 and November 2009 were included in the study. A total of 70 HDPE implants were inserted in 44 patients. All procedures were performed by a single surgeon following standardized pre, intra and post-operative protocols. The results were evaluated with respect to improvement in facial contour desired and achieved, overall patient satisfaction and complications encountered. Results: The study included 44 patients with a male:female ratio of 1:1, a mean age of 25.09 years (14 to 58 years) and a mean follow-up of 45.34 months (0.5 to 100 months). HDPE implants were used to augment the nasal dorsum, maxilla, malar eminence, chin, mandibular body and angle, orbital rim and frontal region. The overall recontouring afforded by the HDPE implants was good, with most patients reporting satisfactory results. There were seven complications (10%), including three cases of deviation (4.29%), three cases of exposure (4.29%) and one case of sub-clinical infection (1.43%). None however necessitated implant removal. Nasal dorsal HDPE implants, especially those involving secondary surgery, suffered a much higher complication rate compared to other implants. Conclusions: HDPE is an alternative to

  18. Long-term results of high-density porous polyethylene implants in facial skeletal augmentation: An Indian perspective.

    PubMed

    Deshpande, Sanjeev; Munoli, Amarnath

    2010-01-01

    With the increasing emphasis on well-sculpted facial features, today there is a growing need for tools to augment the facial skeleton; either for cosmetic reasons or to re-contour deformities-congenital, post-traumatic and post-ablative. The limitations of autogenous materials has lead to evolution of numerous 'alloplasts', of which, high-density porous polyethylene (HDPE) seems to be a promising alternative. To evaluate the long term results of HDPE in facial skeletal augmentation in terms of achieving desired facial contour, patient satisfaction and complications. A tertiary care referral centre in a metropolitan set-up. Case Series All patients undergoing HDPE implant insertion for facial skeletal augmentation between July 2001 and November 2009 were included in the study. A total of 70 HDPE implants were inserted in 44 patients. All procedures were performed by a single surgeon following standardized pre, intra and post-operative protocols. The results were evaluated with respect to improvement in facial contour desired and achieved, overall patient satisfaction and complications encountered. The study included 44 patients with a male:female ratio of 1:1, a mean age of 25.09 years (14 to 58 years) and a mean follow-up of 45.34 months (0.5 to 100 months). HDPE implants were used to augment the nasal dorsum, maxilla, malar eminence, chin, mandibular body and angle, orbital rim and frontal region. The overall recontouring afforded by the HDPE implants was good, with most patients reporting satisfactory results. There were seven complications (10%), including three cases of deviation (4.29%), three cases of exposure (4.29%) and one case of sub-clinical infection (1.43%). None however necessitated implant removal. Nasal dorsal HDPE implants, especially those involving secondary surgery, suffered a much higher complication rate compared to other implants. HDPE is an alternative to autogenous grafts for facial skeletal augmentation with good long-term results and a

  19. Methodology for Long-Term Permeation Test Periods for HD in High-Density Polyethylene: Universal Munitions Storage Container for the Non-Stockpile Chemical Materiel Program

    DTIC Science & Technology

    2016-05-01

    measurements for distilled mustard (HD) and non-welded high-density polyethylene (HDPE) at 120 °F were completed for thicknesses of 20–80 mil for...new capability in permeation cup testing. 15. SUBJECT TERMS Distilled mustard (HD) Container Thickness effect Chemical warfare agent (CWA) Fick’s...temperatures for up to a month. The distilled mustard (HD)- contaminated swatches in the cells would have to be maintained in an independent environmental

  20. Dynamic mechanical analysis of compatibilizer effect on the mechanical properties of wood flour/high-density polyethylene composites

    Treesearch

    Mehdi Behzad; Medhi Tajvidi; Ghanbar Ehrahimi; Robert H. Falk

    2004-01-01

    In this study, effect of MAPE (maleic anhydride polyethylene) as the compatibilizer on the mechanical properties of wood-flour polyethylene composites has been investigated by using Dynamic Mechanical Analysis (DMA). Composites were made at 25% and 50% by weight fiber contents and 1% and 2% compatibilizer respectively. Controls were also made at the same fiber contents...

  1. Effects of environment and gamma irradiation on the mechanical properties of high density polyethylene. [Construction material for LLW high-integrity containers

    SciTech Connect

    Soo, P.; Arora, H.; Swyler, K.J.; Becker, W.; Sobel, E.

    1986-03-01

    An evaluation was made of the effects of environment and gamma irradiation on the short-term tensile and creep properties of Marlex CL-100, a highly cross-linked high-density polyethylene. This material is being considered as a constructional material for a low-level radioactive waste high-integrity container. It was found that the chemical environments studied could be beneficial or detrimental to strength and ductility depending on the type of mechanical property test and the nature of the exposure of the polyethylene to the chemical environment. Gamma irradiation to a sufficiently high dose prior to tensile or creep testing increased the strength and decreased the ductility. In-test irradiation, however, could increase or decrease the creep rate depending on the dose rate and applied stress.

  2. Surface chemistry and mechanical property changes of wood-flour/high-density-polyethylene composites after accelerated weathering

    Treesearch

    Nicole M. Stark; Laurent M. Matuana

    2004-01-01

    Although wood–plastic composites have become more accepted and used in recent years and are promoted as low-maintenance, high-durability building products, they do experience a color change and a loss in mechanical properties with accelerated weathering. In this study, we attempted to characterize the modulus-of-elasticity (MOE) loss of photostabilized high- density...

  3. EVALUATION OF ULTRASONIC PHASED-ARRAY FOR DETECTION OF PLANAR FLAWS IN HIGH-DENSITY POLYETHYLENE (HDPE) BUTT-FUSION JOINTS

    SciTech Connect

    Prowant, Matthew S.; Denslow, Kayte M.; Moran, Traci L.; Jacob, Rick E.; Hartman, Trenton S.; Crawford, Susan L.; Mathews, Royce; Neill, Kevin J.; Cinson, Anthony D.

    2016-09-21

    The desire to use high-density polyethylene (HDPE) piping in buried Class 3 service and cooling water systems in nuclear power plants is primarily motivated by the material’s high resistance to corrosion relative to that of steel and metal alloys. The rules for construction of Class 3 HDPE pressure piping systems were originally published in Code Case N-755 and were recently incorporated into the American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME BPVC) Section III as Mandatory Appendix XXVI (2015 Edition). The requirements for HDPE examination are guided by criteria developed for metal pipe and are based on industry-led HDPE research or conservative calculations.

  4. Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE) Addition.

    PubMed

    Chen, Jinxiang; Wang, Yong; Gu, Chenglong; Liu, Jianxun; Liu, Yufu; Li, Min; Lu, Yun

    2013-06-18

    This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE) enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs). The maximum values of the specific tensile and flexural strengths are achieved at a MAPE content of 5%-8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition.

  5. Enhancement of the Mechanical Properties of Basalt Fiber-Wood-Plastic Composites via Maleic Anhydride Grafted High-Density Polyethylene (MAPE) Addition

    PubMed Central

    Chen, Jinxiang; Wang, Yong; Gu, Chenglong; Liu, Jianxun; Liu, Yufu; Li, Min; Lu, Yun

    2013-01-01

    This study investigated the mechanisms, using microscopy and strength testing approaches, by which the addition of maleic anhydride grafted high-density polyethylene (MAPE) enhances the mechanical properties of basalt fiber-wood-plastic composites (BF-WPCs). The maximum values of the specific tensile and flexural strengths areachieved at a MAPE content of 5%–8%. The elongation increases rapidly at first and then continues slowly. The nearly complete integration of the wood fiber with the high-density polyethylene upon MAPE addition to WPC is examined, and two models of interfacial behavior are proposed. We examined the physical significance of both interfacial models and their ability to accurately describe the effects of MAPE addition. The mechanism of formation of the Model I interface and the integrated matrix is outlined based on the chemical reactions that may occur between the various components as a result of hydrogen bond formation or based on the principle of compatibility, resulting from similar polarity. The Model I fracture occurred on the outer surface of the interfacial layer, visually demonstrating the compatibilization effect of MAPE addition. PMID:28809285

  6. Use of porous high-density polyethylene (Medpor) for spreader or extended septal graft in rhinoplasty: aesthetics, functional outcomes, and long-term complications.

    PubMed

    Kim, Young Hyo; Kim, Beom Joon; Jang, Tae Young

    2011-11-01

    In this study, 29 patients with porous high-density polyethylene (group A) and 29 patients with septal cartilage (group B) were enrolled for either spreader or extended septal graft. By questionnaire or telephone survey, the authors evaluated patients' cosmetic satisfaction and complications. The authors also used postoperative photographs to evaluate cosmetic results. For the functional analysis, the change of visual analog scale of nasal obstruction and change of minimal cross-sectional area using acoustic rhinometry were compared. Of 29 patients in group A, 27 were totally satisfied with the results. There was no complication except for 2 cases of extrusion during 5.3 ± 1.8 years. The patients in group A showed more decrease of nasal obstruction by visual analog scale and more improvement of minimal cross-sectional area as compared with those in group B. Therefore, porous high-density polyethylene is an ideal alloplastic material for spreader or extended septal graft in rhinoplasty in both cosmetic and functional aspects. And it is also safe and stable over a long-term period.

  7. Separation of n-hexane/acetone mixtures by pervaporation using high density polyethylene/ethylene propylene diene terpolymer rubber blend membranes.

    PubMed

    Kumar, P V Anil; Anilkumar, S; Varughese, K T; Thomas, Sabu

    2012-01-15

    Polymer membranes were prepared by blending high density polyethylene (HDPE) with ethylene propylene diene terpolymer rubber (EPDM). These blend membranes were evaluated for the selective separation of n-hexane from acetone. The flux and selectivity of the membranes were determined both as a function of the blend composition and feed mixture composition. Results showed that polymer blending method could be very useful to develop new membranes with improved selectivity. Pervaporation properties could be optimized by adjusting the blend composition. The effects of blend ratio, feed composition, and penetrant size on the pervaporation process were analyzed. The permeation properties have been explained on the basis of interaction between the membrane and solvents and blend morphology. Flux increases with increasing alkane content in the feed composition.

  8. Investigation of the catalytic pyrolysis of high-density polyethylene over a HZSM-5 catalyst in a laboratory fluidized-bed reactor

    SciTech Connect

    Sharratt, P.N.; Lin, Y.H.; Garforth, A.A.; Dwyer, J.

    1997-12-01

    High-density polyethylene (HDPE) was pyrolyzed over HZSM-5 catalyst using a specially developed laboratory fluidized-bed reactor operating isothermally at ambient pressure. The influence of reaction conditions including temperature, ratios of HDPE to catalyst feed, and flow rates of fluidizing gas was examined. The sodium form of siliceous ZSM-5, silicalite, containing very few or no catalytically active sites, gave very low conversions of polymer to volatile hydrocarbons compared with HZSM-5 gave good yields of volatile hydrocarbons with differing selectivities in the final products dependent on reaction conditions. Catalytic pyrolysis of HDPE performed in the fluidized-bed reactor was shown to produce valuable hydrocarbons in the range of C{sub 3}-C{sub 5} carbon number with a high olefinic content. The production of olefins with potential value as a chemical feedstock is potentially attractive and may offer greater profitability than production of saturated hydrocarbons and aromatics.

  9. Effect of Mercerization and Electron-Beam Irradiation on Mechanical Properties of High Density Polyethylene (HDPE) / Brazil Nut Pod Fiber (BNPF) Bio-Composites

    NASA Astrophysics Data System (ADS)

    Campos, Rejane D.; Sotenko, Maria; Hosur, Mahesh; Jeelani, Shaik; Díaz, Francisco R. V.; Moura, Esperidiana A. B.; Kirwan, Kerry; Seo, Emilia S. M.

    The use of natural fibers with polymeric resins has spread rapidly. In order to improve the mechanical properties of material, in this work, two variables were used: mercerization and electron beam irradiation. This paper describes the preparation and characterization of bio-composites that were prepared in two different routes using green high density polyethylene (HDPE) and Brazil nut pod fiber (BNPF): the first was to irradiate the composite with 150 kGy and the second was to irradiate the matrix with 15 kGy followed by composite preparation. In both cases mercerized and non-mercerized fibers were used. The irradiation process was carried out using a 1.5 MeV electron beam accelerator, at room temperature and in the presence of air. The material was characterized to evaluate the effect of treatment on mechanical properties of material.

  10. A comparative study on different ionic liquids used as surfactants: Effect on thermal and mechanical properties of high-density polyethylene nanocomposites.

    PubMed

    Livi, Sébastien; Duchet-Rumeau, Jannick; Pham, Thi-Nhàn; Gérard, Jean-François

    2010-09-01

    Dialkyl imidazolium and alkyl phosphonium salts were synthesized to be used as new surfactants for cationic exchange of layered silicates, such as montmorillonite (MMT). The synthesized phosphonium (P-MMT) or imidazolium ion (I-MMT)-modified montmorillonites display a dramatically improved thermal degradation with respect to commonly used quaternary ammonium salts. This thermal degradation window can still be shifted toward higher temperatures after washing of modified clays. Two kinds of organic species can be identified onto clay: physically adsorbed species versus chemically adsorbed species. To evidence the impact of these thermally resistant ionic liquids, the modified montmorillonites were introduced in a great commodity polymer, i.e., high-density polyethylene. Thermoplastic nanocomposites with a very low amount of nanofillers were processed in melt by twin screw extrusion. If the thermal stability of polyethylene is slightly increased with only 2wt.% of thermostable made clays, the stiffness-toughness compromise is well improved since a strong increase in modulus is achieved with both thermostable clays without loss of fracture properties. But these mechanical performances are mainly obtained with unwashed thermostable clays because the physically adsorbed organic species onto clay surfaces behave like a compatibilizer that helps both the dispersion into the PE matrix and improves the clay/matrix interface quality. Copyright 2009. Published by Elsevier Inc.

  11. Long term performance of polyethylene pipe under high fill. Part 1. Technical report, June 1989-November 1992

    SciTech Connect

    Webb, N.H.; Selig, E.T.

    1994-12-01

    The aim of this study is to improve the knowledge base for the design of non-pressure high density polyethylene (HDPE) pipes under high earth loads. Laboratory tests were performed on HDPE pipe sections to obtain property information. The tests involved the diametrical compression (ring bending) of pipe sections both at various deformation rates to evaluate the effect on pipe stiffness, and also at fixed vertical deflection to evaluate the load relaxation with time. The performance of an HDPE pipe under high fill was monitored during fill construction and for three years after completion of construction. No wall crushing, structural buckling or excess deflection occurred. However, circumferential cracking of the unlined sections at the couplings, and buckling of the liner in the lined sections were observed. Laboratory studies of these two effects will be described in a subsequent technical report. Finite element analysis of the field installation was carried out. The analysis showed that the pipe can sustain circumferential stresses that are much higher than those proposed by current design (1992) procedures.

  12. Effects of inoculation level, material hydration, and stainless steel surface roughness on the transfer of listeria monocytogenes from inoculated bologna to stainless steel and high-density polyethylene.

    PubMed

    Rodríguez, Andrés; Autio, Wesley R; McLandsborough, Lynne A

    2007-06-01

    The influence of inoculation level, material hydration, and stainless steel surface roughness on the transfer of Listeria monocytogenes from inoculated bologna to processing surfaces (stainless steel and polyethylene) was assessed. Slices of bologna (14 g) were inoculated with Listeria at different levels, from 10(5) to 10(9) CFU/cm2. Transfer experiments were done at a constant contact time (30 s) and pressure (45 kPa) with a universal testing machine. After transfer, cells that had been transferred to sterile stainless steel and polyethylene were removed and counted, and the efficiency of transfer (EOT) was calculated. As the inoculation level increased from 10(5) to 10(9) CFU/cm(2), the absolute level of transfer increased in a similar fashion. By calculating EOTs, the data were normalized, and the initial inoculation level had no effect on the transfer (P > 0.05). The influence of hydration level on stainless steel, high-density polyethylene, and material type was investigated, and the EOTs ranged from 0.1 to 1 under all the conditions tested. Our results show that transfers to wetted processing surfaces (mean EOT = 0.43) were no different from dried processing surfaces (mean EOT = 0.35) (P > 0.05). Material type was shown to be a significant factor, with greater numbers of Listeria transferring from bologna to stainless steel (mean EOT = 0.49) than from bologna to polyethylene (mean EOT = 0.28) (P < 0.01). Stainless steel with three different surface roughness (Ra) values of <0.8 microm (target Ra = 0.25, 0.50, and 0.75 Vmicrom) and two different finishes (mechanically polished versus mechanically polished and further electropolished) was used to evaluate its effect on the transfer. The surface roughness and finish on the stainless steel did not have any effect on the transfer of Listeria (P > 0.05). Our results showed that when evaluating the transfer of Listeria, the use of EOTs rather than the absolute transfer values is essential to allow comparisons of

  13. Enhanced biodegradation of low and high-density polyethylene by novel bacterial consortia formulated from plastic-contaminated cow dung under thermophilic conditions.

    PubMed

    Skariyachan, Sinosh; Setlur, Anagha Shamsundar; Naik, Sujay Yashwant; Naik, Ashwini Amaresh; Usharani, Makam; Vasist, Kiran S

    2017-03-01

    The current study aimed to devise eco-friendly, safe, and cost-effective strategies for enhanced degradation of low- and high-density polyethylene (LDPE and HDPE) using newly formulated thermophilic microbial consortia from cow dung and to assess the biodegradation end products. The plastic-degrading bacteria from cow dung samples gathered from highly plastic-acclimated environments were enriched by standard protocols. The degradation ability was comprehended by zone of clearance method, and the percentage of degradation was monitored by weight reduction process. The best isolates were characterized by standard microbiological and molecular biology protocols. The best isolates were employed to form several combinations of microbial consortia, and the degradation end products were analyzed. The stability of 16S ribosomal DNA (rDNA) was predicted by bioinformatics approach. This study identified 75 ± 2, 55 ± 2, 60 ± 3, and 43 ± 3% degradation for LDPE strips, pellets, HDPE strips, and pellets, respectively, for a period of 120 days (p < 0.05) at 55 °C by the formulated consortia of IS1-IS4, and the degradation efficiency was found to be better in comparison with other formulations. The end product analysis by Fourier transform infrared, scanning electron microscopy, energy-dispersive spectroscopy, and nuclear magnetic resonance showed major structural changes and formation of bacterial biofilm on plastic surfaces. These novel isolates were designated as Bacillus vallismortis bt-dsce01, Psuedomonas protegens bt-dsce02, Stenotrophomonas sp. bt-dsce03, and Paenibacillus sp.bt-dsce04 by 16S rDNA sequencing and suggested good gene stability with minimum Gibb's free energy. Therefore, this study imparts substantial information regarding the utilization of these thermophilic microbial consortia from cow dung for rapid polyethylene removal.

  14. Separating effective high density polyethylene segments from olefin block copolymers using high temperature liquid chromatography with a preloaded discrete adsorption promoting solvent barrier.

    PubMed

    Chatterjee, Tirtha; Rickard, Mark A; Pearce, Eric; Pangburn, Todd O; Li, Yongfu; Lyons, John W; Cong, Rongjuan; deGroot, A Willem; Meunier, David M

    2016-09-23

    Recent advances in catalyst technology have enabled the synthesis of olefin block copolymers (OBC). One type is a "hard-soft" OBC with a high density polyethylene (HDPE) block and a relatively low density polyethylene (VLDPE) block targeted as thermoplastic elastomers. Presently, one of the major challenges is to fractionate HDPE segments from the other components in an experimental OBC sample (block copolymers and VLDPE segments). Interactive high temperature liquid chromatography (HTLC) is ineffective for OBC separation as the HDPE segments and block copolymer chains experience nearly identical enthalpic interactions with the stationary phase and co-elute. In this work we have overcome this challenge by using liquid chromatography under the limiting conditions of desorption (LC LCD). A solvent plug (discrete barrier) is introduced in front of the sample which specifically promotes the adsorption of HDPE segments on the stationary phase (porous graphitic carbon). Under selected thermodynamic conditions, VLDPE segments and block copolymer chains crossed the barrier while HDPE segments followed the pore-included barrier solvent and thus enabled separation. The barrier solvent composition was optimized and the chemical composition of fractionated polymer chains was investigated as a function of barrier solvent strength using an online Fourier-transform infrared (FTIR) detector. Our study revealed that both the HDPE segments as well as asymmetric block copolymer chains (HDPE block length≫VLDPE block length) are retained in the separation and the barrier strength can be tailored to retain a particular composition. At the optimum barrier solvent composition, this method can be applied to separate effective HDPE segments from the other components, which has been demonstrated using an experimental OBC sample. Copyright © 2016 Elsevier B.V. All rights reserved.

  15. Characterization of solidified radioactive waste and container due to the incorporation of high density polyethylene granules and powder in mortar matrices

    SciTech Connect

    Peric, A.D.

    1999-07-01

    Powder and granules of the high density polyethylene (PEHD) were used to prepare mortar based matrices for immobilization of radioactive waste materials containing {sup 137}Cs, as well as containers for solidified radioactive waste form. Seven types of matrices, differ due to the percentage of granules and filler material added, were investigated. PEHD powder and granules were added to mortar matrix preparations with the objective of improving physico-chemical characteristics of the radwaste-mortar matrix mixtures, in particular the leach-rate of the immobilized radionuclide, as well as mechanical characteristics either of mortar matrix and container. In this paper, only mechanical strength aspect of the investigated mortar and concrete container formulations, is presented. The equivalent diameter of the PEHD granules used was 2.0 mm. PEHD granules were used to replace 100 volume percent of stone granules, sifted size of 2.0 mm, normally used in the matrix preparation, in order to decrease the porosity and density of the mortar matrix and to avoid segregation of the stone particles at the bottom of the immobilized radioactive waste cylindrical form. PEHD powder, particle size of 250 micrometer, was added as filler to the mortar formulation, replacing 5, 8 and 10 wt% of the total cement weight in matrix formulation and 15 and 18 wt% of the total cement weight in container formulation. Cured samples were investigated on mechanical strength, using 150 MPa hydraulic press, in order to determine influence of added polyethylene granules and powder on samples resistance to mechanical forces that solidified waste materials and concrete containers may experience at the disposal site. Results of performed investigations have shown that samples prepared with polyethylene granules, replacing 100 wt% of the stone granules, have almost twice as much mechanical strength than samples prepared with stone aggregate. Samples prepared with PEHD granules and powder have mechanical

  16. Vibrational spectroscopic and ultrasound analysis for in-process characterization of high-density polyethylene/polypropylene blends during melt extrusion.

    PubMed

    Barnes, S E; Brown, E C; Sibley, M G; Edwards, H G M; Scowen, I J; Coates, P D

    2005-05-01

    Spectroscopic techniques such as Raman, mid-infrared (MIR), and near-infrared (NIR) have become indispensable analytical tools for rapid chemical quality control and process monitoring. This paper presents the application of in-line Fourier transform near-infrared (FT-NIR) spectroscopy, Raman spectroscopy, and ultrasound transit time measurements for in-line monitoring of the composition of a series of high-density polyethylene (HDPE)/polypropylene (PP) blends during single-screw extrusion. Melt composition was determined by employing univariate analysis of the ultrasound transit time data and partial least squares (PLS) multivariate analysis of the data from both spectroscopic techniques. Each analytical technique was determined to be highly sensitive to changes in melt composition, allowing accurate prediction of blend content to within +/- 1% w/w (1sigma) during monitoring under fixed extrusion conditions. FT-NIR was determined to be the most sensitive of the three techniques to changes in melt composition. A four-factor PLS model of the NIR blend spectra allowed determination of melt content with a standard prediction error of +/- 0.30% w/w (1sigma). However, the NIR transmission probes employed for analysis were invasive into the melt stream, whereas the single probes adopted for Raman and ultrasound analysis were noninvasive, making these two techniques more versatile. All three measurement techniques were robust to the high temperatures and pressures experienced during melt extrusion, demonstrating each system's suitability for process monitoring and control.

  17. Synthesis of highly efficient flame retardant high-density polyethylene nanocomposites with inorgano-layered double hydroxides as nanofiller using solvent mixing method.

    PubMed

    Gao, Yanshan; Wang, Qiang; Wang, Junya; Huang, Liang; Yan, Xingru; Zhang, Xi; He, Qingliang; Xing, Zipeng; Guo, Zhanhu

    2014-04-09

    High-density polyethylene (HDPE) polymer nanocomposites containing Zn2Al-X (X= CO3(2-), NO3(-), Cl(-), SO4(2-)) layered double hydroxide (LDH) nanoparticles with different loadings from 10 to 40 wt % were synthesized using a modified solvent mixing method. Synthesized LDH nanofillers and the corresponding nanocomposites were carefully characterized using X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, etc. The thermal stability and flame retardancy behavior were investigated using a thermo gravimetric analyzer and microscale combustion calorimeter. Comparing to neat HDPE, the thermal stability of nanocomposites was significantly enhanced. With the addition of 15 wt % Zn2Al-Cl LDH, the 50% weight loss temperature was increased by 67 °C. After adding LDHs, the flame retardant performance was significantly improved as well. With 40 wt % of LDH loading, the peak heat release rate was reduced by 24%, 41%, 48%, and 54% for HDPE/Zn2Al-Cl, HDPE/Zn2Al-CO3, HDPE/Zn2Al-NO3, and HDPE/Zn2Al-SO4, respectively. We also noticed that different interlayer anions could result in different rheological properties and the influence on storage and loss moduli follows the order of SO4(2-) > NO3(-) > CO3(2-) > Cl(-). Another important finding of this work is that the influence of anions on flame retardancy follows the exact same order on rheological properties.

  18. Optimization of High Temperature and Pressurized Steam Modified Wood Fibers for High-Density Polyethylene Matrix Composites Using the Orthogonal Design Method

    PubMed Central

    Gao, Xun; Li, Qingde; Cheng, Wanli; Han, Guangping; Xuan, Lihui

    2016-01-01

    The orthogonal design method was used to determine the optimum conditions for modifying poplar fibers through a high temperature and pressurized steam treatment for the subsequent preparation of wood fiber/high-density polyethylene (HDPE) composites. The extreme difference, variance, and significance analyses were performed to reveal the effect of the modification parameters on the mechanical properties of the prepared composites, and they yielded consistent results. The main findings indicated that the modification temperature most strongly affected the mechanical properties of the prepared composites, followed by the steam pressure. A temperature of 170 °C, a steam pressure of 0.8 MPa, and a processing time of 20 min were determined as the optimum parameters for fiber modification. Compared to the composites prepared from untreated fibers, the tensile, flexural, and impact strength of the composites prepared from modified fibers increased by 20.17%, 18.5%, and 19.3%, respectively. The effect on the properties of the composites was also investigated by scanning electron microscopy and dynamic mechanical analysis. When the temperature, steam pressure, and processing time reached the highest values, the composites exhibited the best mechanical properties, which were also well in agreement with the results of the extreme difference, variance, and significance analyses. Moreover, the crystallinity and thermal stability of the fibers and the storage modulus of the prepared composites improved; however, the hollocellulose content and the pH of the wood fibers decreased. PMID:28773963

  19. Heat shrinkable behavior, physico-mechanical and structure properties of electron beam cross-linked blends of high-density polyethylene with acrylonitrile-butadiene rubber

    NASA Astrophysics Data System (ADS)

    Reinholds, Ingars; Kalkis, Valdis; Merijs-Meri, Remo; Zicans, Janis; Grigalovica, Agnese

    2016-03-01

    In this study, heat-shrinkable composites of electron beam irradiated high-density polyethylene (HDPE) composites with acrylonitrile-butadiene rubber (NBR) were investigated. HDPE/NBR blends at a ratio of components 100/0, 90/10, 80/20, 50/50 and 20/80 wt% were prepared using a two-roll mill. The compression molded films were irradiated high-energy (5 MeV) accelerated electrons up to irradiation absorbed doses of 100-300 kGy. The effect of electron beam induced cross-linking was evaluated by the changes of mechanical properties, gel content and by the differences of thermal properties, detected by differential scanning calorimetry. The thermo-shrinkage forces were determined as the kinetics of thermorelaxation and the residual shrinkage stresses of previously oriented (stretched up to 100% at above melting temperature of HDPE and followed by cooling to room temperature) specimens of irradiated HDPE/NBR blends under isometric heating-cooling mode. The compatibility between the both components was enhanced due to the formation of cross-linked sites at amorphous interphase. The results showed increase of mechanical stiffness of composites with increase of irradiation dose. The values of gel fraction compared to thermorelaxation stresses increased with the growth of irradiation dose level, as a result of formation cross-linked sites in amorphous PP/NBR interphase.

  20. Optimization of High Temperature and Pressurized Steam Modified Wood Fibers for High-Density Polyethylene Matrix Composites Using the Orthogonal Design Method.

    PubMed

    Gao, Xun; Li, Qingde; Cheng, Wanli; Han, Guangping; Xuan, Lihui

    2016-10-18

    The orthogonal design method was used to determine the optimum conditions for modifying poplar fibers through a high temperature and pressurized steam treatment for the subsequent preparation of wood fiber/high-density polyethylene (HDPE) composites. The extreme difference, variance, and significance analyses were performed to reveal the effect of the modification parameters on the mechanical properties of the prepared composites, and they yielded consistent results. The main findings indicated that the modification temperature most strongly affected the mechanical properties of the prepared composites, followed by the steam pressure. A temperature of 170 °C, a steam pressure of 0.8 MPa, and a processing time of 20 min were determined as the optimum parameters for fiber modification. Compared to the composites prepared from untreated fibers, the tensile, flexural, and impact strength of the composites prepared from modified fibers increased by 20.17%, 18.5%, and 19.3%, respectively. The effect on the properties of the composites was also investigated by scanning electron microscopy and dynamic mechanical analysis. When the temperature, steam pressure, and processing time reached the highest values, the composites exhibited the best mechanical properties, which were also well in agreement with the results of the extreme difference, variance, and significance analyses. Moreover, the crystallinity and thermal stability of the fibers and the storage modulus of the prepared composites improved; however, the hollocellulose content and the pH of the wood fibers decreased.

  1. Enhancement of mechanical strength of TiO{sub 2}/high-density polyethylene composites for bone repair with silane-coupling treatment

    SciTech Connect

    Hashimoto, Masami . E-mail: masami@jfcc.or.jp; Takadama, Hiroaki . E-mail: takadama@jfcc.or.jp; Mizuno, Mineo . E-mail: mizuno@jfcc.or.jp; Kokubo, Tadashi . E-mail: kokubo@isc.chubu.ac.jp

    2006-03-09

    Mechanical properties of composites made up of high-density polyethylene (HDPE) and silanated TiO{sub 2} particles for use as a bone-repairing material were investigated in comparison with those of the composites of HDPE with unsilanized TiO{sub 2} particles. The interfacial morphology and interaction between silanated TiO{sub 2} and HDPE were analyzed by means of Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The absorption in spectral bands related to the carboxyl bond in the silane-coupling agent, the vinyl group in the HDPE, and the formation of the ether bond was studied in order to assess the influence of the silane-coupling agent. The SEM micrograph showed that the 'bridging effect' between HDPE and TiO{sub 2} was brought about by the silane-coupling agent. The use of the silane-coupling agent and the increase of the hot-pressing pressure for shaping the composites facilitated the penetration of polymer into cavities between individual TiO{sub 2} particles, which increased the density of the composite. Therefore, mechanical properties such as bending yield strength and Young's modulus increased from 49 MPa and 7.5 GPa to 65 MPa and 10 GPa, respectively, after the silane-coupling treatment and increase in the hot-pressing pressure.

  2. Heat transfer performance of a phase-change thermal energy storage water heater using cross-linked high density polyethylene pellets

    SciTech Connect

    Jotshi, C.K.; Klausner, J.F.; Goswami, D.Y.; Hsieh, C.K.; Santhosh, M.K.; Colacino, F.

    1996-12-31

    The objective of this investigation was to develop an efficient water heater that stores thermal energy in a mixture of cross-linked high density polyethylene (HDPE) pellets and propylene glycol. Properties of cross-linked HDPE, such as melting and crystallization temperatures, heat of fusion and crystallization, and volume change were measured in the laboratory. The heat transfer coefficient for the mixture was also measured in a laboratory test. A prototype model of a storage water heater using a mixture of cross-linked HDPE pellets and propylene glycol was designed and fabricated. A copper finned heat transfer coil was used to extract the heat from the storage tank by passing water through it. The heat transfer efficiency (heat extracted by water/heat stored) was measured to be about 70%. To increase the efficiency, the storage unit was modified. In the modified unit, the length of the heat transfer coil was increased and coil spacing optimized. With the modification, the heat transfer efficiency was measured to be about 90%. In addition, a variable heat flux heating element, having high heat flux at the bottom and low heat flux at top, was used to reduce thermal stratification of the propylene glycol/HDPE pellet mixture.

  3. Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes.

    PubMed

    Dutra, Camila; Pezo, Davinson; Freire, Maria Teresa de Alvarenga; Nerín, Cristina; Reyes, Felix Guillermo Reyes

    2011-03-11

    A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 μm carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 °C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Effect of reinforcement particle size on in vitro behavior of beta-tricalcium phosphate-reinforced high-density polyethylene: a novel orthopedic composite.

    PubMed

    Homaeigohar, S S H; Shokrgozar, M A; Javadpour, J; Khavandi, A; Sadi, A Yari

    2006-07-01

    Beta-tricalcium phosphate-reinforced high-density polyethylene (beta-TCP/HDPE) is a new biomaterial, which was made to simulate bone composition and study its capacity to act like bony tissues. This material was produced by replacing mineral component and collagen soft tissue of bone with beta-TCP and HDPE, respectively. The biocompatibility of composite samples with different volume fractions of TCP (20, 30, and 40 vol %) and two different particle sizes (80-100 and 120-140 mesh size) was examined in vitro using the osteoblast cell line G-292 by proliferation, alkaline phosphatase (ALP) production, and cell adhesion assays. Cell-material interaction on the surface of the composites was observed by scanning electron microscopy (SEM). The effect of beta-TCP particle size on behavior of the osteoblast cell line was compared between two groups of the composite samples containing smaller and larger reinforcement particle sizes as well as with those of a negative control. In general, results showed that the composite samples containing larger particles supported a higher rate of proliferation and ALP production by osteoblast cells after 3, 7, and 14 days of incubation compared to the composite samples with smaller particle size and control. Furthermore, more cells were attached to the surface of composite samples containing larger particle size when compared to the smaller particle size composites (p<0.05). This number was nearly equal with numbers adhered on negative control [tissue culture polystyrene (TPS)] and significantly higher in comparison with composite control [polyethylene (PE)] (p<0.05). Adhered cells presented a normal morphology by SEM and many of the cells were seen to be undergoing cell division. These findings indicate that beta-TCP/HDPE composites are biocompatible, nontoxic, and in some cases, act to stimulate proliferation of the cells, ALP production, and cell adhesion when compared to the control counterparts. Furthermore, beta-TCP/HDPE samples

  5. Thermal, creep-recovery and viscoelastic behavior of high density polyethylene/hydroxyapatite nano particles for bone substitutes: effects of gamma radiation.

    PubMed

    Alothman, Othman Y; Fouad, H; Al-Zahrani, S M; Eshra, Ayman; Al Rez, Mohammed Fayez; Ansari, S G

    2014-08-28

    High Density Polyethylene (HDPE) is one of the most often used polymers in biomedical applications. The limitations of HDPE are its visco-elastic behavior, low modulus and poor bioactivity. To improve HDPE properties, HA nanoparticles can be added to form polymer composite that can be used as alternatives to metals for bone substitutes and orthopaedic implant applications. In our previous work (BioMedical Engineering OnLine 2013), different ratios of HDPE/HA nanocomposites were prepared using melt blending in a co-rotating intermeshing twin screw extruder. The accelerated aging effects on the tensile properties and torsional viscoelastic behavior (storage modulus (G') and Loss modulus (G")) at 80°C of irradiated and non-irradiated HDPE/HA was investigated. Also the thermal behavior of HDPE/HA were studied. In this study, the effects of gamma irradiation on the tensile viscoelastic behavior (storage modulus (E') and Loss modulus (E")) at 25°C examined for HDPE/HA nanocomposites at different frequencies using Dynamic Mechanical Analysis (DMA). The DMA was also used to analyze creep-recovery and relaxation properties of the nanocomposites. To analyze the thermal behavior of the HDPE/HA nanocomposite, Differential Scanning Calorimetry (DSC) was used. The microscopic examination of the cryogenically fractured surface revealed a reasonable distribution of HA nanoparticles in the HDPE matrix. The DMA showed that the tensile storage and loss modulus increases with increasing the HA nanoparticles ratio and the test frequency. The creep-recovery behavior improves with increasing the HA nanoparticle content. Finally, the results indicated that the crystallinity, viscoelastic, creep recovery and relaxation behavior of HDPE nanocomposite improved due to gamma irradiation. Based on the experimental results, it is found that prepared HDPE nanocomposite properties improved due to the addition of HA nanoparticles and irradiation. So, the prepared HDPE/HA nanocomposite appears to

  6. The Reconstruction of Nasal Septal Perforation with High Density Porous Polyethylene Covered with Fascia Lata: An Experimental Study on Rabbit Model

    PubMed Central

    Onar, Vedat; Sayin, Ibrahim; Onol, Suzan Deniz; Aydin, Tamer

    2011-01-01

    Objectives Evaluation of a new material, high-density porous polyethylene (HDPP), which is covered with fascia lata, for experimental nasal septal perforation closure. Methods Twenty New Zealand albino rabbits were included and divided into study and control groups. A lateral incision was made from the lateral aspect of the left nares to the incisura nasomaxillaris. After exposure of the cavum nasi, the nasal mucoperichondrium was elevated bilaterally. A full-thickness 0.5×0.5-cm perforation was created over the septum nasi with a No. 11 surgical blade. A fascia lata graft was used for the study group. The HDPP was covered with fascia lata and placed under the elevated mucosa. HDPP without a fascial covering was used in the control group. Four months after the procedure, magnetic resonance imaging was performed to evaluate resorption of the material. The animals were sacrificed, and the nasal septum was completely removed. Macroscopic and histopathological examinations were performed on the nasal septum. Results All rabbits had survived after the 4-month period. Macroscopically, nine of 10 (90%) perforations were closed in the fascia lata-covered HDPP group. Histopathological examination of these nine rabbits revealed that the continuity of cartilage was disturbed in the perforation areas. Granulation tissue was inverted in areas in which the cartilage continuity was disturbed. The HDPP had remained intact at the edge of the perforation. In the HDPP group, six of 10 implants were still perforated (60%) and four (40%) were closed. The fascia lata-covered HDPP implant had a significantly higher perforation closure rate than that of the HDPP implant alone (P<0.05). Conclusion In cases of septal perforation, it is better to cover the HDPP implant with fascia lata. This covered implant can be used for the repair of nasal septal perforations. HDPP implants are easy to work with and avoid the increased operative time and morbidity associated with harvesting autografts

  7. Method for assessing lead, cadmium, mercury and arsenic in high-density polyethylene packaging and study of the migration into yoghurt and simulant.

    PubMed

    Kiyataka, Paulo Henrique M; Dantas, Sílvia T; Pallone, Juliana Azevedo Lima

    2014-01-01

    The purpose of this paper was to assess the concentration of lead (Pb), cadmium (Cd), mercury (Hg) and arsenic (As) in high-density polyethylene (HDPE) packaging intended for contact with yoghurt and the migration of these elements using the food itself and 3% acetic acid as a food simulant in accordance to ANVISA, the Brazilian Health Surveillance Agency. In order to perform this study, it was necessary to develop and validate a method by inductively coupled plasma optical emission spectroscopy (ICP-OES) analysis. For method validation, the parameters linearity, limits of detection (LODs) and quantification (LOQs), accuracy and precision were determined. Fifteen commercial samples of yoghurt, marketed in Campinas - São Paulo (Brazil), were used for the analysis. The packaging and yoghurt were digested in high-pressure ashing equipment (HPA) and the migration of the elements into simulant were determined directly in the solution. The validated method proved adequate and the results obtained showed that all the packaging had levels of Hg and Cd below the LOQ, corresponding to 1.0 and 1.5 μg l(-1), respectively. The highest levels of As and Pb were 0.87 and 462.3 mg kg(-1), respectively. The migration of these elements to the yoghurt after 45 days of contact at 4ºC was below the LOQ for all the samples assessed. The results of specific migration into 3% acetic acid simulant showed the concentrations of Cd, Hg and As below 5, 5 and 10 µg kg(-1), respectively, which are the maximum limits set by ANVISA. However, for three samples the packaging lid showed migration of Pb into simulant ranging from 30.6 to 40.2 μg kg(-1), exceeding the limit set by ANVISA of 10 μg kg(-1).

  8. Five-year performance monitoring of a high-density polyethylene (HDPE) cover system at a reclaimed mine waste rock pile in the Sydney Coalfield (Nova Scotia, Canada).

    PubMed

    Power, Christopher; Ramasamy, Murugan; MacAskill, Devin; Shea, Joseph; MacPhee, Joseph; Mayich, David; Baechler, Fred; Mkandawire, Martin

    2017-09-29

    Cover systems are commonly placed over waste rock piles (WRPs) to limit atmospheric water and oxygen ingress and control the generation and release of acid mine drainage (AMD) to the receiving environment. Although covers containing geomembranes such as high-density polyethylene (HDPE) exhibit the attributes to be highly effective, there are few, if any, published studies monitoring their performance at full-scale WRPs. In 2011, a HDPE cover was installed over the Scotchtown Summit WRP in Nova Scotia, Canada, and extensive field performance monitoring was conducted over the next five years. A range of parameters within the atmosphere, cover, waste rock, groundwater and surface water, were monitored and integrated into a comprehensive hydrogeochemical conceptual model to assess (i) atmospheric ingress to the waste rock, (ii) waste rock acidity and depletion and (iii) evolution of groundwater and surface water quality. Results demonstrate that the cover is effective and meeting site closure objectives. Depletion in oxygen influx resulted in slower sulphide oxidation and AMD generation, while a significant reduction in water influx (i.e. 512 to 50 mm/year) resulted in diminished AMD release. Consistent improvements in groundwater quality (decrease in sulphate and metals; increase in pH) beneath and downgradient of the WRP were observed. Protection and/or significant improvement in surface water quality was evident in all surrounding watercourses due to the improved groundwater plume and elimination of contaminated runoff over previously exposed waste rock. A variably saturated flow and contaminant transport model is currently being developed to predict long-term cover system performance.

  9. In vitro and in vivo evaluation of a new nanocomposite, containing high density polyethylene, tricalcium phosphate, hydroxyapatite, and magnesium oxide nanoparticles.

    PubMed

    Pourdanesh, Fereydoun; Jebali, Ali; Hekmatimoghaddam, Seyedhossein; Allaveisie, Azra

    2014-07-01

    In this study, a new nanocomposite, which contained high density polyethylene (HDPE), tricalcium phosphate (Ca3(PO4)2) nanoparticles (TCP NPs), hydroxyapatite nanoparticles (HA NPs), and magnesium oxide nanoparticles (MgO NPs) was prepared. As in vitro experiment, human osteoblasts (HOB) cells were exposed to pristine HDPE and its nanocomposite for a period of 1, 4, and 7 days at 37 °C, and then different assays were carried out, including osteoblast cell proliferation, Trypan blue staining, cell viability, alkaline phosphatase (ALP), and cell adhesion. Antibacterial property of pristine HDPE and its nanocomposite was evaluated, and also their mechanical properties were measured after 2 and 4 months. As in vivo experiment, pristine HDPE and its nanocomposite were separately implanted on calvarium bone of rabbits, and tissue inflammation and osteogenesis were investigated after 2, 4, and 6 months. In case of HOB cells treated with HDPE or nanocomposite, as incubation time was increased, cell proliferation, live/dead ratio, and cell viability were decreased. But, the ALP activity and cell adhesion of HOB cells which treated with nanocomposite were raised after increase of incubation time. This study demonstrated that although the mechanical properties of nanocomposite were similar to HDPE sheet, but their antibacterial property was not similar. The in vivo experiment showed that both pristine HDPE and its nanocomposite had same inflammation responses. Interestingly, osteogenesis was observed after 2 months at bone/nanocomposite interface, and was highly increased after 4 and 6 months. It must be noted that such pattern was not seen at bone/HDPE interface. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Formation of tissue engineered composite construct of cartilage and skin using high density polyethylene as inner scaffold in the shape of human helix.

    PubMed

    Ruszymah, B H I; Chua, K H; Mazlyzam, A L; Aminuddin, B S

    2011-06-01

    Formation of external ear via tissue engineering has created interest amongst surgeons as an alternative for ear reconstruction in congenital microtia. To reconstruct a composite human construct of cartilage and skin in the shape of human ear helix in athymic mice. Six human nasal cartilages were used and digested with Collagenase II. Chondrocytes were passaged in 175 cm(2) culture flasks at a density of 10,000 cells/cm(2). Frozen human plasma was then mixed with human chondrocytes. Six human skin samples were cut into small pieces trypsinized and resuspended. The keratinocytes were plated in six-well plate culture dishes at a density of 2×105 cells per well. Dermis tissues were digested and the fibroblast cells resuspended in six-well plate at the density of 10,000 cells per well. Fibrin-fibroblast layer and fibrin-keratinocytes were formed by mixing with human plasma to create 6 bilayered human skin equivalent (BSE) constructs. The admixture of fibrin chondrocytes layers was wrapped around high density polyethylene (HDP), and implanted at the dorsum of the athymic mice. The construct was left for 4 weeks and after maturation the mice skin above the implanted construct was removed and replaced by BSE for another 4 weeks. Haematoxylin and Eosin showed that the construct consists of fine arrangement and organized tissue structure starting with HDP followed by cartilage, dermis and epidermis. Safranin-O staining was positive for proteoglycan matrix production. Monoclonal mouse antihuman cytokeratin, 34βE12 staining displayed positive result for human keratin protein. The study has shown the possibility to reconstruct ear helix with HDP and tissue engineered human cartilage and skin. This is another step to form a human ear and hopefully will be an alternative in reconstructive ear surgery. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  11. Post-consumer contamination in high-density polyethylene (HDPE) milk bottles and the design of a bottle-to-bottle recycling process.

    PubMed

    Welle, F

    2005-10-01

    Six hundred conventional recycled HDPE flake samples, which were recollected and sorted in the UK, were screened for post-consumer contamination levels. Each analysed sample consisted of 40-50 individual flakes so that the amount of analysed individual containers was in the range 24,000-30,000 post-consumer milk bottles. Predominant contaminants in hot-washed flake samples were unsaturated oligomers, which can be also be found in virgin high-density polyethylene (HDPE) pellet samples used for milk bottle production. In addition, the flavour compound limonene, the degradation product of antioxidant additives di-tert-butylphenol and low amounts of saturated oligomers were found in higher concentrations in the post-consumer samples in comparison with virgin HDPE. However, the overall concentrations in post-consumer recycled samples were similar to or lower than concentration ranges in comparison with virgin HDPE. Contamination with other HDPE untypical compounds was rare and was in most cases related to non-milk bottles, which are <2.1% of the input material of the recycling process. The maximum concentration found in one sample of 1 g was estimated as 130 mg kg(-1), which corresponds to a contamination of 5200-6500 mg kg(-1) in the individual bottle. The recycling process investigated was based on an efficient sorting process, a hot-washing of the ground bottles, and a further deep-cleaning of the flakes with high temperatures and vacuum. Based on the fact that the contamination levels of post-consumer flake samples are similar to virgin HDPE and on the high cleaning efficiency of the super-clean recycling process especially for highly volatile compounds, the recycling process investigated is suitable for recycled post-consumer HDPE bottles for direct food-contact applications. However, hand-picking after automatically sorting is recommended to decrease the amount of non-milk bottles. The conclusions for suitability are valid, provided that the migration testing of

  12. Clinical and histologic response of subcutaneous expanded polytetrafluoroethylene (Gore-Tex) and porous high-density polyethylene (Medpor) implants to acute and early infection.

    PubMed

    Sclafani, A P; Thomas, J R; Cox, A J; Cooper, M H

    1997-03-01

    To examine the responses of subcutaneously implanted expanded polytetrafluoroethylene (e-PTFE, Gore-Tex) and porous high-density polyethylene (PHDPE, Medpor) to experimentally induced infection. Sprague-Dawley rats were implanted subcutaneously with either e-PTFE or PHDPE implants. Inocula of Staphylococcus aureus were injected directly over the implants and the wounds were observed for clinical signs of infection. After the animals were killed, the implants were harvested and underwent Histologic examination. Twenty-eight adult male Sprague-Dawley rats weighing 200 to 250 g. A 8-mm diameter, 1-mm-thick implant of either e-PTFE or PHDPE was placed in a subcutaneous pocket over each animal's dorsum. Either at the time of implantation or 14 days afterward, an inoculum of 10(9) colony-forming units of S aureus was injected transcutaneously directly over each implant. The animals were observed for 7 days before being killed. The implants were harvested and examined by both conventional light and scanning electron microscopy, and the degree of capsule reaction, infection, inflammation, and implant degradation was evaluated. Implants inoculated at the time of implantation were more likely to become clinically infected. Results for e-PTFE and PHDPE implants were similar in this group (5 of 5 e-PTFE and 5 of 5 PHDPE implants infected). The PHDPE implants inoculated 14 days after implantation were less likely to become infected (1 of 4 infected) than e-PTFE implants (3 of 4 infected), and were statistically less likely to become infected than PHDPE implants inoculated immediately after implantation (25% vs 100%; P < .02). Histologically, this resistance to infection correlated with increasing fibrovascular ingrowth into the PHDPE implants. The infected PHDPE implant had little to no ingrowth compared with PHDPE control implants. The uninfected e-PTFE implant had evidence of early fibrovascular ingrowth into the peripheral pores of the implant. Because of differences in pore

  13. Criticality Evaluation of Plutonium-239 Moderated by High-Density Polyethylene in Stainless Steel and Aluminum Containers Suitable for Non-Exclusive Use Transport

    SciTech Connect

    Watson, T T

    2007-08-10

    Research is conducted at the Joint Actinide Shock Physics Experimental Facility (JASPER) on the effects of high pressure and temperature environments on plutonium-239, in support of the stockpile stewardship program. Once an experiment has been completed, it is necessary to transport the end products for interim storage or final disposition. Federal shipping regulations for nonexclusive use transportation require that no more than 180 grams of fissile material are present in at least 360 kilograms of contiguous non-fissile material. To evaluate the conservatism of these regulatory requirements, a worst-case scenario of 180g {sup 239}Pu and a more realistic scenario of 100g {sup 239}Pu were modeled using one of Lawrence Livermore National Laboratory's Monte Carlo transport codes known as COG 10. The geometry consisted of {sup 239}Pu spheres homogeneously mixed with high-density polyethylene surrounded by a cube of either stainless steel 304 or aluminum. An optimized geometry for both cube materials and hydrogen-to-fissile isotope (H/X) ratio were determined for a single unit. Infinite and finite 3D arrays of these optimized units were then simulated to determine if the systems would exceed criticality. Completion of these simulations showed that the optimal H/X ratio for the most reactive units ranged from 800 to 1600. A single unit of either cube type for either scenario would not reach criticality. An infinite array was determined to reach criticality only for the 180g case. The offsetting of spheres in their respective cubes was also considered and showed a considerable decrease in the number of close-packed units needed to reach criticality. These results call into question the current regulations for fissile material transport, which under certain circumstances may not be sufficient in preventing the development of a critical system. However, a conservative, theoretical approach was taken in all assumptions and such idealized configurations may not be likely to

  14. Structure-property relationships: Model studies on melt-extruded uniaxially-oriented high density polyethylene films having well defined morphologies

    NASA Astrophysics Data System (ADS)

    Zhou, Hongyi

    High density polyethylene (HDPE) films having simple and well-defined stacked lamellar morphology, either with or without a distinct presence of row-nucleated fibril structures, have been utilized as model materials to carry out investigations on solid state structure-property relationships. Mechanical tests, including tensile (INSTRON), creep (TMA), and dynamic mechanical (DMTA) tests, were performed at different angles with respect to the original machine direction (MD) of the melt extruded films; morphological changes as a result of these mechanical tests were detected by WAXS, SAXS, and TEM. Crystalline lamellar thickness and its distribution were determined by DSC, SAXS, TEM and AFM experiments. In the large strain deformation study (chapter 4.0), samples were stretched at 00sp°, 45sp° and 90sp° angles with respect to the original MD. A distinct orientation dependence of the tensile behavior was observed and correlated to the corresponding deformation modes and morphological changes, namely (1) lamellar separation and fragmentation by chain slip for the 00sp° stretch, (2) lamellar break-up via chain pull-out for the 90sp° stretch, and (3) lamellar shear, rotation and break-up through chain slip and/or tilt for the 45sp° stretch. A strong strengthening effect was observed for samples with row-nucleated fibril structures at the 00sp° stretch; whereas for the 90sp° stretch, the presence of such structures significantly limited deformability of the samples. In the dynamic strain mechanical alpha relaxation study (chapter 5.0), samples were tested at nine different angles with respect to the original MD, and the morphologies of samples before and after the dynamic tests were also investigated. The mechanical dispersions for the 00sp° and 90sp° tests were believed to arise essentially from the crystalline phase, and they contain contributions from two earlier recognized sub-relaxations of alphasbI and alphasbII. While for the 45sp° test, in addition to a

  15. Improvement of bio-oil yield and quality in co-pyrolysis of corncobs and high density polyethylene in a fixed bed reactor at low heating rate

    NASA Astrophysics Data System (ADS)

    Supramono, D.; Lusiani, S.

    2016-11-01

    Over the past few decades, interest in developing biomass-derived fuel has been increasing rapidly due to the decrease in fossil fuel reserves. Bio-oil produced by biomass pyrolysis however contains high oxygen compounds resulting in low calorific-value fuel and therefore requiring upgrading. In co-pyrolysis of the feed blend of plastics of High Density Polyethylene (HDPE) and biomass of com cob particles, at some compositions free radicals from plastic decomposition containing more hydrogen radicals are able to bond oxygen radicals originating from biomass to reduce oxygenate compounds in the bio-oil thus increasing bio-oil quality. This phenomenon is usually called synergetic effect. In addition to that, the pattern of heating of the feed blend in the pyrolysis reactor is predicted to affect biooil quality and yield. In a batch reactor, co-pyrolysis of corncobs and HDPE requires low heating rate to reach a peak temperature at temperature rise period followed by heating for some time at peak temperature called holding time at constant temperature period. No research has been carried out to investigate how long holding time is set in co-pyrolysis of plastic and biomass to obtain high yield of bio-oil. Holding time may affect either crosslinking of free radicals in gas phase, which increases char product, or secondary pyrolysis in the gas phase, which increases non-condensable gas in the gas phase of pyrolysis reactor, both of which reduce bio-oil yield. Therefore, holding time of co-pyrolysis affects the mass rate of bio-oil formation as the pyrolysis proceeds and quality of the bio-oil. In the present work, effects of holding time on the yield and quality of bio-oil have been investigated using horizontal fixed bed of the feed blends at heating rate of 5°C, peak temperature of 500°C and N2 flow rate of 700 ml/minute. Holding time was varied from 0 to 70 minutes with 10 minutes interval. To investigate the effects of holding time, the composition of HDPE in the

  16. Development of optimum process for electron beam cross-linking of high density polyethylene thermal energy storage pellets, process scale-up and production of application qualities of material

    NASA Technical Reports Server (NTRS)

    Salyer, I. O.

    1980-01-01

    The electron irradiation conditions required to prepare thermally from stable high density polyethylene (HDPE) were defined. The conditions were defined by evaluating the heat of fusion and the melting temperature of several HDPE specimens. The performance tests conducted on the specimens, including the thermal cycling tests in the thermal energy storage unit are described. The electron beam irradiation tests performed on the specimens, in which the total radiation dose received by the pellets, the electron beam current, the accelerating potential, and the atmospheres were varied, are discussed.

  17. Electron beam irradiation of high density polyethylene pellets for thermal energy storage. Final report of Task 1 and Task 2, January 5, 1979-January 4, 1980

    SciTech Connect

    Davison, J.E.; Salyer, I.O.

    1980-05-01

    The objective of this project was to define the electron beam irradiation conditions required to prepare thermally form stable high crystallinity polyethylene (HDPE) pellets which are suitable for thermal energy storage (TES) applications in the temperature interval of 120/sup 0/ to 140/sup 0/C. The optimum material and conditions for electron beam x-linking via evaluation of thermal form stability and retained heat of fusion of HDPE pellets in a laboratory (5 lb) TES unit was defined. 250 pounds of crosslinked HDPE pellets under the optimum conditions defined in Task 1 were manufactured and evaluated for stability to extensive thermocycling in a pilot plant TES unit. Four different HDPE specimens were irradiated under different conditions of the total radiation dose received by the pellets, the electron beam accelerating potential, the electron beam current, the effect of inert atmospheres during irradiation processing, and the effect of stirring the HDPE pellets during the irradiation processing. The experimental values of the heat of fusion and the melting temperature of the irradiated HDPE pellets were measured and compared to the values of the as-received pellets to evaluate the effect of irradiation processing. The results showed that HDPE pellets irradiated to a dose of 8 megarads have sufficient thermal stability and retained heat of fusion to be used as TES material. The manufacture of 15,000 lb of cross linked HDPE pellets for large-scale evaluation TES material for home heating and cooling systems is recommended. (LCL)

  18. Leak detection in polyethylene terephthalate bottles filled with water and pulped and unpulped orange juice using a vacuum decay system.

    PubMed

    Sivaramakrishna, Vijaykrishna; Mehta, Anish; Schramm, Gerhard; Pascall, Melvin A

    2007-10-01

    This research evaluated an offline vacuum decay leak detection system for 1775-ml polyethylene terephthalate (PET) bottles. These bottles were filled with water and pulped and unpulped orange juice and induction sealed with an aluminum liner and an outer 38-mm continuous thread polypropylene cap. The objectives of this study were to evaluate (i) minimum leak size sensitivity of the instrument; (ii) ability to identify weak but nonleaking seals; (iii) effect of varying fill heights on the equipment's sensitivity; and (iv) percentage of false-positive and negative results likely to be obtained during a normal test run. To meet these objectives, leaks 5, 10, 15, 20, 30, 40, and 50 microm were created in the PET bottles. A second set of bottles was induction sealed at high voltage and 1, 1.5, 2, 2.5, 3, 3.5, and 4 s of dwell time. A third set of bottles with good seals was filled with differing headspace measurements of brimful, 1, 2, 3, 4, and 5 cm. After optimizing the equipment, leak tests on random sets of leaking and nonleaking bottles showed 0.0% false-positive and 0.0% negative identifications. Results showed 5-microm minimum leak size detection for bottles filled with all products. Optimum seal conditions were >2 but <3 s at high voltage. Product fill heights >2 to < or =3 cm did not affect the efficiency of the equipment. These results show that this vacuum decay system has potential for use in identifying leaks in PET bottles used for food packaging.

  19. Ultradrawing novel ultra-high molecular weight polyethylene fibers filled with bacterial cellulose nanofibers.

    PubMed

    Yeh, Jen-Taut; Tsai, Chih-Chen; Wang, Chuen-Kai; Shao, Jhih-Wun; Xiao, Ming-Zheng; Chen, Su-Chen

    2014-01-30

    Novel ultrahigh molecular weight polyethylene (UHMWPE)/bacterial cellulose (BC) (F100BCy) and UHMWPE/modified bacterial cellulose (MBC) (F100MBCx-y) as-prepared fibers were prepared and ultra-drawn. The achievable draw ratio (Dra) values of each F100MBCx-y as-prepared fiber series specimens approached a maximum value as their MBC contents reached the optimal value at 0.0625phr. In which, the maximum Dra value obtained for F100MBCx-0.0625 as-prepared fiber specimen prepared at the optimal MBC content reached another maximum value at 347 as the weight ratio of maleic anhydride grafted polyethylene to BC approach an optimal value at 10. In contrast, no significant improvement in Dra values was found for F100BCy as-prepared fiber specimens. To understand these interesting ultradrawing properties described above, Fourier transform infra-red, specific surface areas, and transmission electron microcopic analyses of original and modified BC nanofibers together with the thermal, orientation and tensile properties of F100BCy and F100MBCx-y fiber specimens were performed.

  20. Effect of γ-aminopropyltriethoxy silane (γ-APS) coupling agent on mechanical and morphological properties of high density polyethylene (HDPE)/acrylonitrile butadiene rubber (NBR)/palm pressed fibre (PPF) composites

    NASA Astrophysics Data System (ADS)

    Norizan, Nabila Najwa; Santiagoo, Ragunathan; Ismail, Hanafi

    2017-07-01

    The fabrication of High Density Polyethylene (HDPE)/ Acrylonitrile-butadiene rubber (NBR)/ Palm Pressed Fibre (PPF) composite were investigated. The effect of γ-Aminopropyltriethoxy Silane (APS) as coupling agent on the properties of HDPE/ NBR/ PPF composite were studied. The composites were melt mixed using heated two roll mill at 180°C and speed of 15rpm with six different loading (100/0/10, 80/20/10, 70/30/10, 60/40/10, 50/50/10, and 40/60/10). The effects of γ-APS silane on mechanical, and morphological properties were examined using universal tensile machine (UTM) and scanning electron microscopy (SEM), respectively. Tensile strength and Young's modulus of HDPE/ NBR/ PPF composites decrease with increasing of NBR loading, whilst increasing the elongation at break. However, treated composites have resulted 3% to 29%, and 9% to 19%, higher in tensile strength and young's modulus compared to untreated composites. This was due to the better adhesion between HDPE/ NBR matrices and PPF filler with the presence of silanol moieties. From the morphological study, the micrograph of treated composites has proved the well bonded and good attachment of PPF filler with HDPE/ NBR matrices which resulted to better tensile strength to the HDPE/ NBR/ PPF composites.

  1. In vitro osteogenic cell proliferation, mineralization, and in vivo osseointegration of injection molded high-density polyethylene-based hybrid composites in rabbit animal model.

    PubMed

    Tripathi, Garima; Basu, Bikramjit

    2014-07-01

    The present work reports the biocompatibility property of injection molded HDPE-HA-Al2O3 hybrid composites. In vitro cytocompatibility results reveal that osteogenic cell viability and bone mineralization are favorably supported in a statistically significant manner on HDPE-20% HA-20% Al2O3 composite, in comparison to HDPE-40 wt.% HA or HDPE-40 wt.% Al2O3 The difference in cytocompatibility property is explained in terms of difference in substrate wettability/surface energy and importantly, both the cell proliferation at 7 days or bone mineralization at 21 days on HDPE-20% HA-20% Al2O3 composite are either comparable or better than sintered HA. The progressive healing of cylindrical femoral bone defects in rabbit animal model was assessed by implantation experiments over 1, 4 and 12 weeks. Based on the histological analysis as well as histomorphometrical evaluation, a better efficacy of HDPE-20% HA-20% Al2O3 over high-density polyethylene (HDPE) for bone regeneration and neobone formation at host bone-implant interface was established. Taken together, the present study unequivocally establishes that despite the presence of 20% Al2O3, HDPE-based hybrid composites are as biocompatible as HA in vitro or better than HDPE in vivo. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  2. Chitosan filled recycled low density polyethylene composite: Melt flow behaviour and thermal degradation properties

    NASA Astrophysics Data System (ADS)

    Lim, B. Y.; Voon, C. H.; Salmah, H.; Nordin, H.

    2016-07-01

    An environmentally friendly composite was fabricated from chitosan and recycled low density polyethylene (rLDPE) with the means of melt mixing at 180 °C. The composites were prepared in different loading (10, 20, 30 and 40 php) of chitosan. Due to the incompatibility between filler and matrix, a coupling agent, Ultraplus TP01, was added into the composites. The melt flow index (MFI) values of rLDPE/chitosan composites decreased with chitosan loading but increased with rise of temperature. With the presence of Ultraplus TP01, MFI values of composites were decreased. The thermal stability of rLDPE/chitosan was reduced with increase of chitosan loading but increased with addition of Ultraplus TP01. It was believed that Ultraplus TP01 had provided better interfacial bonding between chitosan and rLDPE, thus enhanced the thermal stability of rLDPE/chitosan composites.

  3. Mechanical properties of low-density polyethylene filled by graphite nanoplatelets.

    PubMed

    Carotenuto, G; De Nicola, S; Palomba, M; Pullini, D; Horsewell, A; Hansen, T W; Nicolais, L

    2012-12-07

    The mechanical properties of GNP/LDPE nanocomposites (graphite nanoplatelets/low density polyethylene) have been investigated, in order to establish the effect of nanoscale reinforcement within the polymer matrix. Results show that the presence of the filler does not involve a change in the microscopic structure of the polymer. However, on a macroscopic scale, GNPs limit the mobility of the polymer chains, resulting in an increase in stiffness for the final composite. Orientation of GNPs within the LDPE matrix is also an important issue that affects mechanical properties and it has been evaluated by testing nanocomposites made by different manufacturing techniques (compression moulding and blown extrusion). The comparison between the experimental data and the Halpin-Tsai model shows that the orientation of GNPs due to the extrusion process leads to values of tensile modulus higher than that obtained with the randomly oriented disposition resulting from the compression moulding technique.

  4. Mechanical properties of low-density polyethylene filled by graphite nanoplatelets

    NASA Astrophysics Data System (ADS)

    Carotenuto, G.; De Nicola, S.; Palomba, M.; Pullini, D.; Horsewell, A.; Hansen, T. W.; Nicolais, L.

    2012-12-01

    The mechanical properties of GNP/LDPE nanocomposites (graphite nanoplatelets/low density polyethylene) have been investigated, in order to establish the effect of nanoscale reinforcement within the polymer matrix. Results show that the presence of the filler does not involve a change in the microscopic structure of the polymer. However, on a macroscopic scale, GNPs limit the mobility of the polymer chains, resulting in an increase in stiffness for the final composite. Orientation of GNPs within the LDPE matrix is also an important issue that affects mechanical properties and it has been evaluated by testing nanocomposites made by different manufacturing techniques (compression moulding and blown extrusion). The comparison between the experimental data and the Halpin-Tsai model shows that the orientation of GNPs due to the extrusion process leads to values of tensile modulus higher than that obtained with the randomly oriented disposition resulting from the compression moulding technique.

  5. Pervaporation and sorption behavior of zeolite-filled polyethylene glycol hybrid membranes for the removal of thiophene species.

    PubMed

    Lin, Ligang; Zhang, Yuzhong; Li, Hong

    2010-10-01

    Polyethylene glycol (PEG)-CuY zeolite hybrid membranes were prepared for sulfur removal from gasoline feed. The sorption and diffusion behavior of typical gasoline components through the hybrid membranes has been investigated by systematic studies of dynamic sorption curves. Influencing factors including feed temperature, permeate pressure, and zeolite content in the membranes on membrane performance have been evaluated. Immersion experiments results showed the preferential sorption of thiophene, which is key in fulfilling the separation of thiophene/hydrocarbon mixtures. The sorption, diffusion, and permeation coefficients of gasoline components in filled membranes are higher than those in unfilled membranes. Pervaporation (PV) and gas chromatography (GC) experiments results corresponded to the discussions on dynamic sorption curves. PV experiments showed that lower permeate pressure meant higher separation performance. The optimum temperature occurred at 383K, and an Arrhenius relationship existed between permeation flux and operating temperature. The CuY zeolite filling led to a significant increase of flux since the porous zeolite provides for more diffusion for small molecules in mixed matrix membranes. The sulfur enrichment factor increased first and then decreased with the increasing zeolite content, which was attributed to the combined influence of complexation force between CuY and thiophenes as well as the trade-off phenomenon between flux and selectivity. At 9 wt% CuY content, a higher permeation flux (3.19 kg/(m(2) h)) and sulfur enrichment factor (2.95) were obtained with 1190 microg/g sulfur content level in gasoline feed.

  6. Poly(ethylene oxide)-Based Composite Electrolytes Filled with Periodic Mesoporous Silica for Solid State Ionics

    NASA Astrophysics Data System (ADS)

    Tominaga, Yoichi; Morita, Masahiro; Asai, Shigeo; Sumita, Masao

    Mesoporous silica (MPS) was used for poly(ethylene oxide) (PEO)-based solid polymer electrolytes as novel inorganic filler. For improvement in ionic conductivity in solid state, a room temperature ionic liquid (IL), 1-ethyl-3-methylimidazolium tetrafluoroborate, was introduced into periodic nano-tunnels of MPS, and the modified MPS (IL-MPS) was filled with PEO-LiBF4 electrolyte. Ionic conductivity of neat-MPS-filled composites was approximately 4-fold higher than that of the original electrolyte. On the other hand, the conductivity was more than 11-fold enhanced by addition of IL-MPS, to be more than 10-6 S/cm at 30°C and at least 10 wt% silica contents. The conductivity increased with increasing IL-MPS contents, to be a maximum value of approximately 3×10-6 S/cm at 30°C and at 40 wt%. Dynamic mechanical measurements for neat- and IL-MPS composites revealed that the addition of fillers improves storage modulus of PEO-based electrolytes at room temperature. The addition of IL-MPS was able to realize the improvement in both ionic conductivity and storage modulus.

  7. Preparation and Characterisation of Linear Low-Density Polyethylene / Thermoplastic Starch Blends Filled with Banana Fibre

    NASA Astrophysics Data System (ADS)

    Kahar, A. W. M.; Ann, L. Ju

    2017-06-01

    In this study, the influence of banana fibre (BF) loading using sodium hydroxide (NaOH) pre-treated and succinic anhydride-treated (SA) BF on the mechanical properties of linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) matrix is investigated. LLDPE/TPS/BF composites were developed under different BF conditions, with and without chemical modifications with the BF content ranging from 5% to 30% based on the total composite. The tensile strength showed an increase with an increase of fibre content up to 10%, thereby decreasing gradually beyond this level. NaOH pre-treated and SA treated BF added with LLDPE/TPS composite displays a higher tensile strength as compared to untreated BF in LLDPE/TPS composites. Thermal behaviour of the BF incorporated in LLDPE/TPS composite was characterised using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). This showed that SA treated BF exhibits better thermal stability, compared to other composites. This is because of the improvement in interfacial adhesion existing between both the fibre and matrix. In addition, a morphology study confirmed that pre-treated and treated BF had excellent interfacial adhesion with LLDPE/TPS matrix, leading to better mechanical properties of resultant composites.

  8. Comparative study of the safety and efficacy of the Ahmed glaucoma valve model M4 (high density porous polyethylene) and the model S2 (polypropylene) in patients with neovascular glaucoma.

    PubMed

    Gil-Carrasco, F; Jiménez-Román, J; Turati-Acosta, M; Bello-López Portillo, H; Isida-Llerandi, C G

    2016-09-01

    To prospectively evaluate the safety and efficacy of the Ahmed glaucoma valve model M4 (High density porous polyethylene plate; Medpor) compared with the model S2 (polypropylene plate). Mexican patients with neovascular glaucoma were randomly included for each group (M4 and S2). They were operated on using conventional techniques and creating a sub-episcleral tunnel to place the valve tube in the anterior chamber. After one year of follow-up, the results were evaluated with respect to a post-operative reduction in pressure, changes in visual acuity, the need for drugs, and complications, as well as the demographic characteristics of each group. Each operation using the M4 valve was performed by a single surgeon (FGC). Those operated on using the S2 model had their surgery performed by the staff surgeons at the Glaucoma Department of the Mexican Association to Prevent Blindness (APEC). Each group (M4 and S2) contained 21 eyes of 21 Mexican patients with a diagnosis of neovascular glaucoma, leading to a total of 42 patients undergoing surgery. The mean preoperative intraocular pressure (IOP) was 43.5 (±11.8), and 42.24 (±12.84) mmHg for the M4 and S2 groups, respectively. After one year of follow-up, the IOP reported was 18.9 (±9.7) mmHg for the final 18 patients in the M4 group, and 16.38 (±9.76) mmHg for the 21 patients in the S2 group. The design of a drainage valve device such as that of Ahmed has characteristics such as moderate control of IOP, thanks to the valve component in the immediate post-operative period, which makes them safer than other non-valve devices. This avoids an excess of flat chambers and the presence of low IOPs, which can lead to bleeding in the early post-operative period due to the weak desmosomal junctions of the newly formed vessels, with the advantage of maintaining suitable control of IOP from the first day after surgery. Further studies with longer follow-up with a larger number of patients are needed to evaluate the effectiveness

  9. Investigation of the oxygen depletion properties of low density polyethylene resins filled with thermally stable oxygen scavengers

    NASA Astrophysics Data System (ADS)

    Yeh, Jen-taut; Cui, Li; Sun, Yan-bin; Xu, Li-ping; Wei, Wei; Tsai, Fang-chang; Jiang, Tao; Zhu, Ping; Huang, Chi-Yuan; Chen, Kan-Nan

    2009-07-01

    The thermal stability, oxygen depletion and tensile properties of low density polyethylene (LDPE) resins filled with ascorbic acid (Vc), sodium ascorbate (SA), iron (Fe) and modified iron (MFe) oxygen scavengers were systematically investigated. Thermogravimetric analysis (TGA) results clearly suggest that the thermal stability of SA powder and L95(SA)5 specimen is significantly better than that of Vc powder and L95(Vc)5 specimen, respectively. The oxygen depletion efficiency of L95(SA)5 is significantly better than that of L95(Vc)5, L95(Fe)5 and L95(MFe)5 specimens, although the virgin SA powders exhibit worse oxygen depletion efficiency than Vc, Fe or MFe powders before melt blending. Moreover, at a fixed weight ratio of Vc (or SA) to MFe of the oxygen scavenger compounds, the oxygen depletion efficiency of L95[SAx(MFe)y]5 series specimens is always significantly better than that of L95[Vcx(MFe)y]5 series specimens. In fact, at weight ratios of Vc/MFe and SA/MFe higher than 3/7 and 5/5, respectively, the residual oxygen concentration values present in the airtight flask of L95[Vcx(MFe)y]5 and L95[SAx(MFe)y]5 series samples at any time are even lower than those of the L95(Vc)5 and L95(SA)5 specimens, respectively. Further tensile experiments show that the tensile properties of the L95[SAx(MFe)y]5 series samples are always higher than those of the corresponding L95[Vcx(MFe)y]5 series samples with the same loadings of oxygen scavenger compounds, respectively. In order to understand these interesting thermal stability, oxygen depletion and tensile properties of these LDPE oxygen-scavenging plastics, scanning electron microscope and energy dispersive X-rays analysis of the compositions on the surfaces of L95[SAx(MFe)y]5 and L95[Vcx(MFe)y]5 series samples were performed. Possible reasons accounting for these interesting properties of these LDPE oxygen-scavenging plastics are proposed.

  10. Spatially revolved high density electroencephalography

    NASA Astrophysics Data System (ADS)

    Wu, Jerry; Szu, Harold; Chen, Yuechen; Guo, Ran; Gu, Xixi

    2015-05-01

    Electroencephalography (EEG) measures voltage fluctuations resulting from ionic current flows within the neurons of the brain. In practice, EEG refers to the recording of the brain's spontaneous electrical activity over a short period of time, several tens of minutes, as recorded from multiple electrodes placed on the scalp. In order to improve the resolution and the distortion cause by the hair and scalp, large array magnetoencephalography (MEG) systems are introduced. The major challenge is to systematically compare the accuracy of epileptic source localization with high electrode density to that obtained with sparser electrode setups. In this report, we demonstrate a two dimension (2D) image Fast Fourier Transform (FFT) analysis along with utilization of Peano (space-filling) curve to further reduce the hardware requirement for high density EEG and improve the accuracy and performance of the high density EEG analysis. The brain-computer interfaces (BCIs) in this work is enhanced by A field-programmable gate array (FPGA) board with optimized two dimension (2D) image Fast Fourier Transform (FFT) analysis.

  11. High density laser-driven target

    DOEpatents

    Lindl, John D.

    1981-01-01

    A high density target for implosion by laser energy composed of a central quantity of fuel surrounded by a high-Z pusher shell with a low-Z ablator-pusher shell spaced therefrom forming a region filled with low-density material.

  12. High density pixel array

    NASA Technical Reports Server (NTRS)

    Wiener-Avnear, Eliezer (Inventor); McFall, James Earl (Inventor)

    2004-01-01

    A pixel array device is fabricated by a laser micro-milling method under strict process control conditions. The device has an array of pixels bonded together with an adhesive filling the grooves between adjacent pixels. The array is fabricated by moving a substrate relative to a laser beam of predetermined intensity at a controlled, constant velocity along a predetermined path defining a set of grooves between adjacent pixels so that a predetermined laser flux per unit area is applied to the material, and repeating the movement for a plurality of passes of the laser beam until the grooves are ablated to a desired depth. The substrate is of an ultrasonic transducer material in one example for fabrication of a 2D ultrasonic phase array transducer. A substrate of phosphor material is used to fabricate an X-ray focal plane array detector.

  13. Scale effects in tribological properties of solid-lubricating composites made of ultra-high molecular weight polyethylene filled with calcium stearate particles

    NASA Astrophysics Data System (ADS)

    Lurie, S. A.; Volkov-Bogorodskiy, D. B.; Knyzeva, A. G.; Panin, S. V.; Kornienko, L. A.

    2016-04-01

    Friction properties being influenced by scale effects are simulated in the paper by the example of polymer composite material made from Ultra High-Molecular Weight Polyethylenes (UHMWPE) filled by calcium stearate (C36H70CaO4). Of interest are the composites whose mechanical properties and tribotechnical characteristics do not depend monotonically on filler (inclusions) weight fraction. In order to describe the influence of scale effects onto frictional properties the model based on Reiss averaging (model of "weak phase") is employed. It is also suggested that when gradient elasticity theory is applicable the formal analogy between effective friction coefficient for surface heterogeneous structures and effective mechanical properties (compliances) for heterogeneous material can take place. Theoretical dependence to describe nonmonotonic change of effective friction coefficient versus filler concentration was obtained for the polymer composites under study. The suggested expressions might be useful for the sake of properties prognosis of antifriction polymeric materilas.

  14. Effect of liquid epoxidized natural rubber (LENR) on mechanical properties and morphology of natural rubber/high density polyethylene/mengkuang fiber (NR/HDPE/MK) bio-composite

    NASA Astrophysics Data System (ADS)

    Piah, Mohd Razi Mat; Baharum, Azizah

    2016-11-01

    The use of mengkuang fiber (MK) fibers in NR/HDPE (40/60) blend was studied via surface modification of fiber. The MK fiber was pre-washed with 5%wt/v sodium hydroxide solution prior to treatment with liquid epoxidized natural rubber (LENR). The concentration of LENR were varied from 5%-20%wt in toluene. The effects of LENR concentrations were studied in terms of mechanical properties and morphology formed. Melt-blending was performed using an internal mixer (Haake Rheomix 600). The processing parameters identified were 135°C temperature, 45 rpm rotor speed, 12 minutes processing time and at 20%wt MK fiber loading. The optimum LENR treatment concentration was obtained at 5%wt with tensile strength, tensile modulus, and impact strength of 10.3 MPa, 414.2 MPa and 14.4 kJ/m2 respectively. The tensile modulus of LENR-treated MK fiber filled NR/HDPE bio-composite has shown enhancement up to 16.7% higher than untreated MK fiber. The tensile and impact strength were decreased with increasing LENR concentration due to the broken of MK fibers to smaller particles and adhered to each other. FESEM micrographs confirmed the formation of fiber-fiber agglomeration in NR/HDPE blends. The optical microscope analysis shows MK fibers is shorter than original fiber lengths after NaOH-LENR surface modification. The internal bonding forces of MK fiber seems to be weaker than external force exerted on it, therefore, the MK fiber has broken to smaller particles and reduced the mechanical properties of NR/HDPE/MK(20%) bio-composite.

  15. Laminated thermoplastic composite material from recycled high density polyethylene

    NASA Technical Reports Server (NTRS)

    Liu, Ping; Waskom, Tommy L.

    1994-01-01

    The design of a materials-science, educational experiment is presented. The student should understand the fundamentals of polymer processing and mechanical property testing of materials. The ability to use American Society for Testing and Materials (ASTM) standards is also necessary for designing material test specimens and testing procedures. The objectives of the experiment are (1) to understand the concept of laminated composite materials, processing, testing, and quality assurance of thermoplastic composites and (2) to observe an application example of recycled plastics.

  16. PSD Applicability: TEX-USS High Density Polyethylene Plant

    EPA Pesticide Factsheets

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  17. The characterization of high-density polyethylene/organoclay nanocomposites

    NASA Astrophysics Data System (ADS)

    Rodrigues, Tathiane Cordeiro; Tavares, Maria Inês Bruno; Soares, Igor Lopes; Moreira, Ana M.

    2009-01-01

    Polymeric nanocomposites, which are hybrids of polymers and modified inorganic clay with organic surfactants, are extremely attractive in both science and industry. These materials present improvements in such polymer properties as modulus, heat capacity, thermal stability, flame resistance, and so on. Research has been conducted in recent decades to obtain high-quality materials that can be used in applications like food packing, car components, and combustible cells. Polymeric nanocomposites present many advantages in relation to composites due to the quantity of filler added to the polymer and also to the improved properties. In a composite, the quantity of filler must be as high as possible (i.e., over 30%). In the polymeric nanocomposite the quantity of filler varies from 1% to 5% because of the nanosize of the particles. These nanoparticles often have a large surface area that results in improved polymer-matrix properties.

  18. Processing torque and thermal properties of kenaf (KNF) filled linear low-density polyethylene/poly (vinyl alcohol) (LLDPE/PVOH) composites with addition of 3-(trimethoxysilyl)propyl methacrylate

    NASA Astrophysics Data System (ADS)

    Ling, Pang Ai; Ismail, Hanafi; Bakar, Azhar Abu

    2017-07-01

    Processing torque and thermal properties of kenaf (KNF)-filled linear low-density polyethylene/poly (vinyl alcohol) (LLDPE/PVOH) composites with and without 3-(trimethoxysilyl)propyl methacrylate were studied. The composites were prepared by using Thermo Haake Polydrive internal mixer at 150°C and 50 rpm for 10 min. The results indicated that the KNF-filled LLDPE/PVOH composites with 3-(trimethoxysilyl)propyl methacrylate possessed higher processing torque and thermal properties compared to composites without 3-(trimethoxysilyl)propyl methacrylate.

  19. Photoionization and High Density Gas

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Bautista, M.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    We present results of calculations using the XSTAR version 2 computer code. This code is loosely based on the XSTAR v.1 code which has been available for public use for some time. However it represents an improvement and update in several major respects, including atomic data, code structure, user interface, and improved physical description of ionization/excitation. In particular, it now is applicable to high density situations in which significant excited atomic level populations are likely to occur. We describe the computational techniques and assumptions, and present sample runs with particular emphasis on high density situations.

  20. High density fluoride glass calorimeter

    NASA Astrophysics Data System (ADS)

    Xie, Q.; Scheltzbaum, J.; Akgun, U.

    2014-04-01

    The unprecedented radiation levels in current Large Hadron Collider runs, and plans to even increase the luminosity creates a need for new detector technologies to be investigated. Quartz plates to replace the plastic scintillators in current LHC calorimeters have been proposed in recent reports. Quartz based Cherenkov calorimeters can solve the radiation damage problem, however light production and transfer have proven to be challenging. This report summarizes the results from a computational study on the performance of a high-density glass calorimeter. High-density, scintillating, fluoride glass, CHG3, was used as the active material. This glass has been developed specifically for hadron collider experiments, and is known for fast response time, in addition to high light yield. Here, the details of a Geant4 model for a sampling calorimeter prototype with 20 layers, and its hadronic as well as electromagnetic performances are reported.

  1. Engineering and Design: Field Applications of Polyethylene Pipe in Dredging

    DTIC Science & Technology

    1986-12-15

    resistance of high density polyethylene ( HDPE ) pipe with convmtimal mild steel pipe as reported at the ASCE Dredging Conference 1984. A third...material, ultra high molecular weight high density polyethylene was also tested. The results indicate that under the test conditions HDPE outperforms mild...steady increase in the number of dredges using high density polyethylene ( HDPE ) pipe in discharge lines. HDPE’s increased popularity is the result of

  2. High Density Methane Storage in Nanoporous Carbon

    NASA Astrophysics Data System (ADS)

    Rash, Tyler; Dohnke, Elmar; Soo, Yuchoong; Maland, Brett; Doynov, Plamen; Lin, Yuyi; Pfeifer, Peter; Mriglobal Collaboration; All-Craft Team

    2014-03-01

    Development of low-pressure, high-capacity adsorbent based storage technology for natural gas (NG) as fuel for advanced transportation (flat-panel tank for NG vehicles) is necessary in order to address the temperature, pressure, weight, and volume constraints present in conventional storage methods (CNG & LNG.) Subcritical nitrogen adsorption experiments show that our nanoporous carbon hosts extended narrow channels which generate a high surface area and strong Van der Waals forces capable of increasing the density of NG into a high-density fluid. This improvement in storage density over compressed natural gas without an adsorbent occurs at ambient temperature and pressures ranging from 0-260 bar (3600 psi.) The temperature, pressure, and storage capacity of a 40 L flat-panel adsorbed NG tank filled with 20 kg of nanoporous carbon will be featured.

  3. High-density digital recording

    NASA Technical Reports Server (NTRS)

    Kalil, F. (Editor); Buschman, A. (Editor)

    1985-01-01

    The problems associated with high-density digital recording (HDDR) are discussed. Five independent users of HDDR systems and their problems, solutions, and insights are provided as guidance for other users of HDDR systems. Various pulse code modulation coding techniques are reviewed. An introduction to error detection and correction head optimization theory and perpendicular recording are provided. Competitive tape recorder manufacturers apply all of the above theories and techniques and present their offerings. The methodology used by the HDDR Users Subcommittee of THIC to evaluate parallel HDDR systems is presented.

  4. Phase structure and properties of poly(ethylene terephthalate)/polyethylene based on recycled materials

    Treesearch

    Yong Lei; Qinglin Wu; Craig M. Clemons; Weihong. Guo

    2009-01-01

    Blends based on recycled high density polyethylene (R-HDPE) and recycled poly(ethylene terephthalate) (R-PET) were made through reactive extrusion. The effects of maleated polyethylene (PE-g-MA), triblock copolymer of styrene and ethylene/butylene (SEBS), and 4,40-methylenedi(phenyl isocyanate) (MDI) on blend properties were studied. The 2% PE-g-MA improved the...

  5. Spacelab high density digital recorders

    NASA Technical Reports Server (NTRS)

    Blais, R. A.

    1983-01-01

    The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.

  6. Spacelab high density digital recorders

    NASA Technical Reports Server (NTRS)

    Blais, R. A.

    1983-01-01

    The design and performance of the high-density digital recorder (HDDR) developed for use at the NASA centers (KSC, JSC, and GSFC) and at the JPL to store and retrieve 50-Mb/s PCM data streams from the Spacelab experiments are reported. The recording reproduction, and transport requirements are reviewed; and the design solutions adopted in the final version of the HDDR are described, incuding three-position-modulation and Y-phase encoding, microprocessor-controlled automatic bit synchronization and equalization, cyclic-redundancy-check error detection and correction, clock regeneration, data and clock variations, tape-speed control, and EEE-488 remote control. Reliable performance, with bit error rates 1 in 10 to the 10th forward and 1 in 10 to the 9th reverse or better and packing density up to 50 percent greater than that obtainable using conventional codes, is reported after 1.5 years of service.

  7. The Radiothermoluminescence Of The Chlorinated Polyethylene

    NASA Astrophysics Data System (ADS)

    Polizov, Hristo T.

    2007-04-01

    The radiothermoluminescence (RTL) of the high density polyetilene (HDPE) by gamma-irradiation was studied together with the thermally stimulated currents (TSC). The investigation was carried for several kind of samples: pure high density polyethlene and chlorinated high density polyethlene with 7, 28 and 42 per cent chlorine. It has been established, that the intensity of the radiothermoluminescence decreases on the high density polyethylene with the chlorination and the thermally stimulated currents increase as a function of the temperature T has been observed as well that a new phase has been formed in the chlorinated polyethylene with the both methods of the investigation.

  8. High density harp for SSCL linac

    SciTech Connect

    Fritsche, C.T.; Krogh, M.L.; Crist, C.E.

    1993-05-01

    AlliedSignal Inc., Kansas City Division, and the Superconducting Super Collider Laboratory (SSCL) are collaboratively developing a high density harp for the SSCL linac. This harp is designed using hybrid microcircuit (HMC) technology to obtain a higher wire density than previously available. The developed harp contains one hundred twenty-eight 33-micron-diameter carbon wires on 0.38-mm centers. The harp features an onboard broken wire detection circuit. Carbon wire preparation and attachment processes were developed. High density surface mount connectors were located. The status of high density harp development will be presented along with planned future activities.

  9. Rheological properties of polyolefin composites highly filled with calcium carbonate

    NASA Astrophysics Data System (ADS)

    Nobile, Maria Rossella; Fierro, Annalisa; Jakubowska, Paulina; Sterzynski, Tomasz

    2016-05-01

    In this paper the rheological properties of highly filled polyolefin composites (HFPCs) have been investigated. Calcium carbonate (CaCO3), with stearic acid modified surface, was used as filler. Ternary compounds have been obtained by the inclusion of a CaCO3/polypropylene master batch into the high density polyethylene matrix. The highly filled polyolefin composites with CaCO3 content in the range between 40 and 64 wt% have been prepared in the molten state using a single-screw extruder, the temperature of the extrusion die was set at 230°C. The melt rheological properties of the HFPCs have been extensively investigated both in oscillatory and steady shear flow.

  10. High density load bearing insulation peg

    DOEpatents

    Nowobilski, J.J.; Owens, W.J.

    1985-01-29

    A high density peg is disclosed which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure. 4 figs.

  11. High density load bearing insulation peg

    DOEpatents

    Nowobilski, Jeffert J.; Owens, William J.

    1985-01-01

    A high density peg which can support a large load and exhibits excellent thermal resistance produced by a method wherein the peg is made in compliance with specified conditions of time, temperature and pressure.

  12. High Density Fuel Development for Research Reactors

    SciTech Connect

    Daniel Wachs; Dennis Keiser; Mitchell Meyer; Douglas Burkes; Curtis Clark; Glenn Moore; Jan-Fong Jue; Totju Totev; Gerard Hofman; Tom Wiencek; Yeon So Kim; Jim Snelgrove

    2007-09-01

    An international effort to develop, qualify, and license high and very high density fuels has been underway for several years within the framework of multi-national RERTR programs. The current development status is the result of significant contributions from many laboratories, specifically CNEA in Argentina, AECL in Canada, CEA in France, TUM in Germany, KAERI in Korea, VNIIM, RDIPE, IPPE, NCCP and RIARR in Russia, INL, ANL and Y-12 in USA. These programs are mainly engaged with UMo dispersion fuels with densities from 6 to 8 gU/cm3 (high density fuel) and UMo monolithic fuel with density as high as 16 gU/cm3 (very high density fuel). This paper, mainly focused on the French & US programs, gives the status of high density UMo fuel development and perspectives on their qualification.

  13. Profiles in garbage: Polyethylene terephthalate

    SciTech Connect

    Miller, C.

    1997-11-01

    Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks -- along with salad dressing, fruit juices, peanut butter, and other household and consumer products -- use PET bottles. PET also is used for film, sheeting for cups and food trays, oven-safe trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early 1970s. Because it is an ``engineered`` resin, PET is more expensive than commodity resins such as high-density polyethylene (HDPE) and, for the same reason, it is usually the highest valued plastic recyclable.

  14. Reliability of PWB Microvias for High Density Package Assembly

    NASA Technical Reports Server (NTRS)

    Ghaffarian, Reza

    2008-01-01

    High density PWB (printed wiring board) with microvia technology is required for implementation of high density and high I/O area array packages (AAP). COTS (commercial off-the-shelf) AAP packaging technologies in high reliability versions with 1.27 mm pitch are now being considered for use in a number of NASA systems including Space Shuttle and Mars Rovers. NASA functional system designs are requiring more and more dense AAP packages and board space, which makes board microvia technology very attractive for effectively routing a large number of package inputs/outputs. However, the reliability of the fine feature microvias including via in pads is unknown for space applications. Understanding process and QA (quality assurance) indicators for reliability are important for low risk insertion of these newly available packages and PWBs. This paper presents literature search as well as test results for a high density board subjected to various thermal cycle and reflow profiles representative of tin-lead and lead-free solder reflow. Microvias sizes ranged from two to six mil with and without filling. Daisy chain microvias monitored during the test and PWBs were cross-sectioned to determine failure and locations. Optical and SEM photographs as well as resistance changes during cycling and Tg/Td (glass transition/decomposition temperature) characterisations are presented.

  15. Reliability of PWB Microvias for High Density Package Assembly

    NASA Technical Reports Server (NTRS)

    Ghaffarian, Reza

    2008-01-01

    High density PWB (printed wiring board) with microvia technology is required for implementation of high density and high I/O area array packages (AAP). COTS (commercial off-the-shelf) AAP packaging technologies in high reliability versions with 1.27 mm pitch are now being considered for use in a number of NASA systems including Space Shuttle and Mars Rovers. NASA functional system designs are requiring more and more dense AAP packages and board space, which makes board microvia technology very attractive for effectively routing a large number of package inputs/outputs. However, the reliability of the fine feature microvias including via in pads is unknown for space applications. Understanding process and QA (quality assurance) indicators for reliability are important for low risk insertion of these newly available packages and PWBs. This paper presents literature search as well as test results for a high density board subjected to various thermal cycle and reflow profiles representative of tin-lead and lead-free solder reflow. Microvias sizes ranged from two to six mil with and without filling. Daisy chain microvias monitored during the test and PWBs were cross-sectioned to determine failure and locations. Optical and SEM photographs as well as resistance changes during cycling and Tg/Td (glass transition/decomposition temperature) characterisations are presented.

  16. IMMUNOLOGIC STUDIES OF HUMAN HIGH DENSITY LIPOPROTEINS

    PubMed Central

    DeLalla, Louis; Levine, Lawrence; Brown, Ray K.

    1957-01-01

    High density serum lipoprotein underwent serologic and physicochemical alterations on aging during storage at 0°C. for 1 month, as judged by decrease of diffusion coefficient and increase of C' fixation. Ultracentrifugation, dialysis, and high concentrations of sodium chloride did not cause these changes. A protein sedimenting at density 1.24 in the ultracentrifuge reacted with antiserum to high density lipoprotein. Probably it was the protein portion of α lipoprotein dissociated from the lipide during ultracentrifugation. Although the antiserum to high density lipoprotein did not react with low density lipoprotein prepared from normal serum, it reacted with similarly prepared lipoproteins from the serum of a patient with biliary cirrhosis. PMID:13449236

  17. High Density Digital Data Storage System

    NASA Technical Reports Server (NTRS)

    Wright, Kenneth D., II; Gray, David L.; Rowland, Wayne D.

    1991-01-01

    The High Density Digital Data Storage System was designed to provide a cost effective means for storing real-time data from the field-deployable digital acoustic measurement system. However, the high density data storage system is a standalone system that could provide a storage solution for many other real time data acquisition applications. The storage system has inputs for up to 20 channels of 16-bit digital data. The high density tape recorders presently being used in the storage system are capable of storing over 5 gigabytes of data at overall transfer rates of 500 kilobytes per second. However, through the use of data compression techniques the system storage capacity and transfer rate can be doubled. Two tape recorders have been incorporated into the storage system to produce a backup tape of data in real-time. An analog output is provided for each data channel as a means of monitoring the data as it is being recorded.

  18. Nasal reconstruction using porous polyethylene implants.

    PubMed

    Romo, T; Sclafani, A P; Jacono, A A

    2000-01-01

    Nasal reconstruction presents a significant challenge to the facial plastic surgeon. The dual goals of reconstruction are restoration of the desired aesthetic nasal contour and an improved nasal airway. Autologous cartilage and bone are considered optimal grafting material, but their supply is often limited and harvesting entails additional morbidity. Many synthetic materials have been introduced in nasal reconstruction, but high infection and extrusion rates limited their use. Porous high density polyethylene implants present an alternative to autologous material as they allow for fibrovascular ingrowth, leading to stability of the implant and decreased rates of infection. Herein we describe the use of porous high density polyethylene implants for reconstruction of the platyrrhine nose and in revision rhinoplasty. The use of preformed nasal-dorsal tip and alar batten implants are described, as well as the use of columellar strut and premaxillary plumper implants. We believe that porous high density polyethylene implants provide a safe, desirable alternative in functional and aesthetic nasal reconstruction.

  19. Aerodynamic Focusing Of High-Density Aerosols

    SciTech Connect

    Ruiz, D. E.; Fisch, Nathaniel

    2014-02-24

    High-density micron-sized particle aerosols might form the basis for a number of applications in which a material target with a particular shape might be quickly ionized to form a cylindrical or sheet shaped plasma. A simple experimental device was built in order to study the properties of high-density aerosol focusing for 1 m silica spheres. Preliminary results recover previous findings on aerodynamic focusing at low densities. At higher densities, it is demonstrated that the focusing properties change in a way which is consistent with a density dependent Stokes number.

  20. TECHNICAL GUIDANCE DOCUMENT: THE FABRICATION OF POLYETHYLENE FML FIELD SEAMS

    EPA Science Inventory

    This technical guidance document is meant to augment the numerous construction quality control and construction assurance (CQC and CQA) guidelines that are presently available for high density polyethylene (HDPE) liner installation and inspection.

  1. TECHNICAL GUIDANCE DOCUMENT: THE FABRICATION OF POLYETHYLENE FML FIELD SEAMS

    EPA Science Inventory

    This technical guidance document is meant to augment the numerous construction quality control and construction assurance (CQC and CQA) guidelines that are presently available for high density polyethylene (HDPE) liner installation and inspection.

  2. Meson Masses in High Density QCD

    SciTech Connect

    Silas R. Beane; Paulo F. Bedaque; Martin J. Savage

    2000-06-15

    The low-energy effective theories for the two- and three-flavor color-superconductors arising in the high density limit of QCD are discussed. Using an effective field theory to describe quarks near the fermi surface, we compute the masses of the pseudo-Goldstone bosons that dominate the low-momentum dynamics of these systems.

  3. Unconventional High Density Vertically Aligned Conducting Polymer

    DTIC Science & Technology

    2014-08-21

    CVD) method on silicon substrates using iron (Fe) on alumina as a catalyst . The as-grown A-CNT forests have a 1% volume fraction (Vf) of CNTs with...here, consisting of the anode of the conformal coating of oCVD PEDOT on A-CNTs (PEDOT/A-CNTs) and ultra-high density graphene-oxide cathode ( HD -a

  4. Supernovae and high density nuclear matter

    SciTech Connect

    Kahana, S.

    1986-01-01

    The role of the nuclear equation of state (EOS) in producing prompt supernova explosions is examined. Results of calculations of Baron, Cooperstein, and Kahana incorporating general relativity and a new high density EOS are presented, and the relevance of these calculations to laboratory experiments with heavy ions considered. 31 refs., 6 figs., 2 tabs.

  5. Approach of high density coal preparation method

    SciTech Connect

    Yang, Y.; Chen, Q.

    1996-12-31

    Density difference of aged anthracite coal of high density and discard is less than that of general coal and discard; conventional separation methods are difficult to be used. For the special coal, coal dry beneficiation technology with air-dense medium fluidized bed has obvious superiority over other separation methods.

  6. High Density Diffusion-Free Nanowell Arrays

    PubMed Central

    Takulapalli, Bharath R; Qiu, Ji; Magee, D. Mitchell; Kahn, Peter; Brunner, Al; Barker, Kristi; Means, Steven; Miersch, Shane; Bian, Xiaofang; Mendoza, Alex; Festa, Fernanda; Syal, Karan; Park, Jin; LaBaer, Joshua; Wiktor, Peter

    2012-01-01

    Proteomics aspires to elucidate the functions of all proteins. Protein microarrays provide an important step by enabling high-throughput studies of displayed proteins. However, many functional assays of proteins include untethered intermediates or products, which could frustrate the use of planar arrays at very high densities because of diffusion to neighboring features. The nucleic acid programmable protein array (NAPPA), is a robust, in situ synthesis method for producing functional proteins just-in-time, which includes steps with diffusible intermediates. We determined that diffusion of expressed proteins led to cross-binding at neighboring spots at very high densities with reduced inter-spot spacing. To address this limitation, we have developed an innovative platform using photolithographically-etched discrete silicon nanowells and used NAPPA as a test case. This arrested protein diffusion and cross-binding. We present confined high density protein expression and display, as well as functional protein-protein interactions, in 8,000 nanowell arrays. This is the highest density of individual proteins in nano-vessels demonstrated on a single slide. We further present proof of principle results on ultra-high density protein arrays capable of up to 24,000 nanowells on a single slide. PMID:22742968

  7. The high density Z-pinch

    SciTech Connect

    McCall, G.H.

    1988-01-01

    During the past few years techniques have been developed for producing pinches in solid deuterium. The conditions which exist in these plasmas are quiet different from those produced earlier. The pinch is formed from a fiber of solid deuterium rather than from a low density gas, and the current is driven by a low impedance, high voltage pulse generator. Because of the high initial density, it is not necessary to compress the pinch to reach thermonuclear conditions, and the confinement time required for energy production is much shorter than for a gas. The experimental results, which have been verified by experiments performed at higher current were quite surprising and encouraging. The pinch appeared to be stable for a time much longer than the Alfven radial transit time. In this paper, however, I argue that the pinch is not strictly stable, but it does not appear to disassemble in a catastrophic fashion. It appears that there may be a distinction between stability and confinement in the high density pinch. In the discussion below I will present the status of the high density Z-pinch experiments at laboratories around the world, and I will describe some of the calculational and experimental results. I will confine my remarks to recent work on the high density pinch. 17 refs. 10 figs.

  8. The yield behavior of polyethylene tubes subjected to biaxial loadings

    NASA Technical Reports Server (NTRS)

    Semeliss, M.; Wong, R.; Tuttle, M.

    1990-01-01

    High-density polyethylene is subjected to biaxial states of stress to examine the yield behavior of the semicrystalline thermoplastic under constant octahedral shear-stress rates. Combinations of internal pressures and axial loads are applied to thin-walled tubes of polyethylene, and the strain response in the axial and hoop directions are measured. The polyethylene specimens are found to be anisotropic, and the experimental measurements are compared to yield criteria that are applicable to isotropic and anisotropic materials.

  9. High density scintillating glass proton imaging detector

    NASA Astrophysics Data System (ADS)

    Wilkinson, C. J.; Goranson, K.; Turney, A.; Xie, Q.; Tillman, I. J.; Thune, Z. L.; Dong, A.; Pritchett, D.; McInally, W.; Potter, A.; Wang, D.; Akgun, U.

    2017-03-01

    In recent years, proton therapy has achieved remarkable precision in delivering doses to cancerous cells while avoiding healthy tissue. However, in order to utilize this high precision treatment, greater accuracy in patient positioning is needed. An accepted approximate uncertainty of +/-3% exists in the current practice of proton therapy due to conversions between x-ray and proton stopping power. The use of protons in imaging would eliminate this source of error and lessen the radiation exposure of the patient. To this end, this study focuses on developing a novel proton-imaging detector built with high-density glass scintillator. The model described herein contains a compact homogeneous proton calorimeter composed of scintillating, high density glass as the active medium. The unique geometry of this detector allows for the measurement of both the position and residual energy of protons, eliminating the need for a separate set of position trackers in the system. Average position and energy of a pencil beam of 106 protons is used to reconstruct the image rather than by analyzing individual proton data. Simplicity and efficiency were major objectives in this model in order to present an imaging technique that is compact, cost-effective, and precise, as well as practical for a clinical setting with pencil-beam scanning proton therapy equipment. In this work, the development of novel high-density glass scintillator and the unique conceptual design of the imager are discussed; a proof-of-principle Monte Carlo simulation study is performed; preliminary two-dimensional images reconstructed from the Geant4 simulation are presented.

  10. Study On Temperature Distribution In T Fittings - Polyethylene Natural Gas Pipes Assemblies

    NASA Astrophysics Data System (ADS)

    Avrigean, Eugen

    2015-09-01

    The present paper intends to approach theoretically and experimentally an important topic concerning the operational safety of the polyethylene pipes used in natural gas distribution. We discuss the influence of temperature in the high density polyethylene elbows during welding to the polyethylene pipes.

  11. High density circuit technology, part 1

    NASA Technical Reports Server (NTRS)

    Wade, T. E.

    1982-01-01

    The metal (or dielectric) lift-off processes used in the semiconductor industry to fabricate high density very large scale integration (VLSI) systems were reviewed. The lift-off process consists of depositing the light-sensitive material onto the wafer and patterning first in such a manner as to form a stencil for the interconnection material. Then the interconnection layer is deposited and unwanted areas are lifted off by removing the underlying stencil. Several of these lift-off techniques were examined experimentally. The use of an auxiliary layer of polyimide to form a lift-off stencil offers considerable promise.

  12. Regulation of high density lipoprotein levels

    SciTech Connect

    Krauss, R.M.

    1982-03-01

    An increasing awareness of the physiologic and pathologic importance of serum high density lipoproteins (HDL) has led to a large number of observations regarding factors which influence their concentrations. HDL consists of a heterogeneous collection of macromolecules with diverse physical properties and chemical constituents. While laboratory techniques have made it possible to measure HDL and their individual components, there are as yet large gaps in our knowledge of the biochemical mechanisms and clinical significance of changes in these laboratory parameters. In this review, current concepts of the structure and metabolism of HDL will be briefly summarized, and the factors influencing their levels in humans will be surveyed. 313 references.

  13. Two-color QCD at high density

    SciTech Connect

    Boz, Tamer; Skullerud, Jon-Ivar; Giudice, Pietro; Hands, Simon; Williams, Anthony G.

    2016-01-22

    QCD at high chemical potential has interesting properties such as deconfinement of quarks. Two-color QCD, which enables numerical simulations on the lattice, constitutes a laboratory to study QCD at high chemical potential. Among the interesting properties of two-color QCD at high density is the diquark condensation, for which we present recent results obtained on a finer lattice compared to previous studies. The quark propagator in two-color QCD at non-zero chemical potential is referred to as the Gor’kov propagator. We express the Gor’kov propagator in terms of form factors and present recent lattice simulation results.

  14. Method of high-density foil fabrication

    DOEpatents

    Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.

    2003-12-16

    A method for preparing flat foils having a high density includes the steps of mixing a powdered material with a binder to form a green sheet. The green sheet is exposed to a high intensity radiative source adapted to emit radiation of wavelengths corresponding to an absorption spectrum of the powdered material. The surface of the green sheet is heated while a lower sub-surface temperature is maintained. An apparatus for preparing a foil from a green sheet using a radiation source is also disclosed.

  15. Evaluation of Paulownia elongata wood polyethylene composites

    USDA-ARS?s Scientific Manuscript database

    Paulownia wood flour (PWF), a byproduct of milling lumber, was employed as a bio-filler and blended with high density polyethylene (HDPE) via extrusion. Paulownia wood (PW) shavings were milled through a 1-mm screen then separated via shaking into various particle fractions using sieves (#30 - < #2...

  16. Some novel phenomena at high density

    NASA Astrophysics Data System (ADS)

    Berkowitz, Evan Scott

    Astrophysical environments probe matter in ways impossible on Earth. In particular, matter in compact objects are extraordinarily dense. In this thesis we discuss two phenomena that may occur at high density. First, we study toroidal topological solitons called vortons, which can occur in the kaon-condensed color-flavor-locked phase of high-density quark matter, a candidate phase for the core of some neutron stars. We show that vortons have a large radius compared to their thickness if their electrical charge is on the order of 104 times the fundamental charge. We show that shielding of electric fields by electrons dramatically reduces the size of a vorton. Second, we study an unusual phase of degenerate electrons and nonrelativistic Bose-condensed helium nuclei that may exist in helium white dwarfs. We show that this phase supports a previously-unknown gapless mode, known as the half-sound, that radically alters the material's specific heat, and can annihilate into neutrinos. We provide evidence that this neutrino radiation is negligible compared to the star's surface photoemission.

  17. Spin Polarization in High Density Quark Matter

    NASA Astrophysics Data System (ADS)

    Bohr, Henrik; Panda, Prafulla K.; Providência, Constança; da Providência, João

    2013-04-01

    We investigate the occurrence of a ferromagnetic phase transition in high density hadronic matter (e.g., in the interior of a neutron star). This could be induced by a four-fermion interaction analogous to the one which is responsible for chiral symmetry breaking in the Nambu-Jona-Lasinio model, to which it is related through a Fierz transformation. Flavor SU(2) and flavor SU(3) quark matter are considered. A second-order phase transition is predicted at densities about 5 times the normal nuclear matter density. It is also found that in flavor SU(3) quark matter, a first-order transition from the so-called 2 flavor super-conducting phase to the ferromagnetic phase arises. The color-flavor-locked phase may be completely hidden by the FP.

  18. Ultra-high density diffraction grating

    DOEpatents

    Padmore, Howard A.; Voronov, Dmytro L.; Cambie, Rossana; Yashchuk, Valeriy V.; Gullikson, Eric M.

    2012-12-11

    A diffraction grating structure having ultra-high density of grooves comprises an echellette substrate having periodically repeating recessed features, and a multi-layer stack of materials disposed on the echellette substrate. The surface of the diffraction grating is planarized, such that layers of the multi-layer stack form a plurality of lines disposed on the planarized surface of the structure in a periodical fashion, wherein lines having a first property alternate with lines having a dissimilar property on the surface of the substrate. For example, in one embodiment, lines comprising high-Z and low-Z materials alternate on the planarized surface providing a structure that is suitable as a diffraction grating for EUV and soft X-rays. In some embodiments, line density of between about 10,000 lines/mm to about 100,000 lines/mm is provided.

  19. Nanotechnology for Synthetic High Density Lipoproteins

    PubMed Central

    Luthi, Andrea J.; Patel, Pinal C.; Ko, Caroline H.; Mutharasan, R. Kannan; Mirkin, Chad A.; Thaxton, C. Shad

    2014-01-01

    Atherosclerosis is the disease mechanism responsible for coronary heart disease (CHD), the leading cause of death worldwide. One strategy to combat atherosclerosis is to increase the amount of circulating high density lipoproteins (HDL), which transport cholesterol from peripheral tissues to the liver for excretion. The process, known as reverse cholesterol transport, is thought to be one of the main reasons for the significant inverse correlation observed between HDL blood levels and the development of CHD. This article highlights the most common strategies for treating atherosclerosis using HDL. We further detail potential treatment opportunities that utilize nanotechnology to increase the amount of HDL in circulation. The synthesis of biomimetic HDL nanostructures that replicate the chemical and physical properties of natural HDL provides novel materials for investigating the structure-function relationships of HDL and for potential new therapeutics to combat CHD. PMID:21087901

  20. Cortical High-Density Counterstream Architectures

    PubMed Central

    Markov, Nikola T.; Ercsey-Ravasz, Mária; Van Essen, David C.

    2014-01-01

    Small-world networks provide an appealing description of cortical architecture owing to their capacity for integration and segregation combined with an economy of connectivity. Previous reports of low-density interareal graphs and apparent small-world properties are challenged by data that reveal high-density cortical graphs in which economy of connections is achieved by weight heterogeneity and distance-weight correlations. These properties define a model that predicts many binary and weighted features of the cortical network including a core-periphery, a typical feature of self-organizing information processing systems. Feedback and feedforward pathways between areas exhibit a dual counterstream organization, and their integration into local circuits constrains cortical computation. Here, we propose a bow-tie representation of interareal architecture derived from the hierarchical laminar weights of pathways between the high-efficiency dense core and periphery. PMID:24179228

  1. Cortical high-density counterstream architectures.

    PubMed

    Markov, Nikola T; Ercsey-Ravasz, Mária; Van Essen, David C; Knoblauch, Kenneth; Toroczkai, Zoltán; Kennedy, Henry

    2013-11-01

    Small-world networks provide an appealing description of cortical architecture owing to their capacity for integration and segregation combined with an economy of connectivity. Previous reports of low-density interareal graphs and apparent small-world properties are challenged by data that reveal high-density cortical graphs in which economy of connections is achieved by weight heterogeneity and distance-weight correlations. These properties define a model that predicts many binary and weighted features of the cortical network including a core-periphery, a typical feature of self-organizing information processing systems. Feedback and feedforward pathways between areas exhibit a dual counterstream organization, and their integration into local circuits constrains cortical computation. Here, we propose a bow-tie representation of interareal architecture derived from the hierarchical laminar weights of pathways between the high-efficiency dense core and periphery.

  2. Fluid hydrogen at high density - Pressure dissociation

    NASA Technical Reports Server (NTRS)

    Saumon, Didier; Chabrier, Gilles

    1991-01-01

    A model for the Helmholtz free energy of fluid hydrogen at high density and high temperature is developed. This model aims at describing both pressure and temperature dissociation and ionization and bears directly on equations of state of partially ionized plasmas, as encountered in astrophysical situations and high-pressure experiments. This paper focuses on a mixture of hydrogen atoms and molecules and is devoted to the study of the phenomenon of pressure dissociation at finite temperatures. In the present model, the strong interactions are described with realistic potentials and are computed with a modified Weeks-Chandler-Andersen fluid perturbation theory that reproduces Monte Carlo simulations to better than 3 percent. Theoretical Hugoniot curves derived from the model are in excellent agreement with experimental data.

  3. High Density Mastering Using Electron Beam

    NASA Astrophysics Data System (ADS)

    Kojima, Yoshiaki; Kitahara, Hiroaki; Kasono, Osamu; Katsumura, Masahiro; Wada, Yasumitsu

    1998-04-01

    A mastering system for the next-generation digital versatile disk (DVD) is required to have a higher resolution compared with the conventional mastering systems. We have developed an electron beam mastering machine which features a thermal field emitter and a vacuum sealed air spindle motor. Beam displacement caused by magnetic fluctuation with spindle rotation was about 60 nm(p-p) in both the radial and tangential directions. Considering the servo gain of a read-out system, it has little influence on the read-out signal in terms of tracking errors and jitters. The disk performance was evaluated by recording either the 8/16 modulation signal or a groove on the disk. The electron beam recording showed better jitter values from the disk playback than those from a laser beam recorder. The deviation of track pitch was 44 nm(p-p). We also confirmed the high density recording with a capacity reaching 30 GB.

  4. Fluid hydrogen at high density - Pressure dissociation

    NASA Technical Reports Server (NTRS)

    Saumon, Didier; Chabrier, Gilles

    1991-01-01

    A model for the Helmholtz free energy of fluid hydrogen at high density and high temperature is developed. This model aims at describing both pressure and temperature dissociation and ionization and bears directly on equations of state of partially ionized plasmas, as encountered in astrophysical situations and high-pressure experiments. This paper focuses on a mixture of hydrogen atoms and molecules and is devoted to the study of the phenomenon of pressure dissociation at finite temperatures. In the present model, the strong interactions are described with realistic potentials and are computed with a modified Weeks-Chandler-Andersen fluid perturbation theory that reproduces Monte Carlo simulations to better than 3 percent. Theoretical Hugoniot curves derived from the model are in excellent agreement with experimental data.

  5. Manufacture of high-density ceramic sinters

    NASA Technical Reports Server (NTRS)

    Hibata, Y.

    1986-01-01

    High density ceramic sinters are manufactured by coating premolded or presintered porous ceramics with a sealing material of high SiO2 porous glass or nitride glass and then sintering by hot isostatic pressing. The ceramics have excellent abrasion and corrosion resistances. Thus LC-10 (Si3N2 powder) and Y2O3-Al2O3 type sintering were mixed and molded to give a premolded porous ceramic (porosity 37%, relative bulk density 63%). The ceramic was dipped in a slurry containing high SiO2 porous glass and an alcohol solution of cellulose acetate and dried. The coated ceramic was treated in a nitrogen atmosphere and then sintered by hot isostatic pressing to give a dense ceramic sinter.

  6. Ground state of high-density matter

    NASA Technical Reports Server (NTRS)

    Copeland, ED; Kolb, Edward W.; Lee, Kimyeong

    1988-01-01

    It is shown that if an upper bound to the false vacuum energy of the electroweak Higgs potential is satisfied, the true ground state of high-density matter is not nuclear matter, or even strange-quark matter, but rather a non-topological soliton where the electroweak symmetry is exact and the fermions are massless. This possibility is examined in the standard SU(3) sub C tensor product SU(2) sub L tensor product U(1) sub Y model. The bound to the false vacuum energy is satisfied only for a narrow range of the Higgs boson masses in the minimal electroweak model (within about 10 eV of its minimum allowed value of 6.6 GeV) and a somewhat wider range for electroweak models with a non-minimal Higgs sector.

  7. Structures of High Density Molecular Fluids

    SciTech Connect

    Baer, B; Cynn, H; Iota, V; Yoo, C-S

    2002-02-01

    The goal of this proposal is to develop an in-situ probe for high density molecular fluids. We will, therefore, use Coherent Anti-Stokes Raman Spectroscopy (CARS) applied to laser heated samples in a diamond-anvil cell (DAC) to investigate molecular fluids at simultaneous conditions of high temperatures (T > 2000K) and high pressures (P > 10 GPa.) Temperatures sufficient to populate vibrational levels above the ground state will allow the vibrational potential to be mapped by CARS. A system capable of heating and probing these samples will be constructed. Furthermore, the techniques that enable a sample to be sufficiently heated and probed while held at static high pressure in a diamond-anvil-cell will be developed. This will be an in-situ investigation of simple molecules under conditions relevant to the study of detonation chemistry and the Jovain planet interiors using state of the art non-linear spectroscopy, diamond-anvil-cells, and laser heating technology.

  8. High-density fiber optic biosensor arrays

    NASA Astrophysics Data System (ADS)

    Epstein, Jason R.; Walt, David R.

    2002-02-01

    Novel approaches are required to coordinate the immense amounts of information derived from diverse genomes. This concept has influenced the expanded role of high-throughput DNA detection and analysis in the biological sciences. A high-density fiber optic DNA biosensor was developed consisting of oligonucleotide-functionalized, 3.1 mm diameter microspheres deposited into the etched wells on the distal face of a 500 micrometers imaging fiber bundle. Imaging fiber bundles containing thousands of optical fibers, each associated with a unique oligonucleotide probe sequence, were the foundation for an optically connected, individually addressable DNA detection platform. Different oligonucleotide-functionalized microspheres were combined in a stock solution, and randomly dispersed into the etched wells. Microsphere positions were registered from optical dyes incorporated onto the microspheres. The distribution process provided an inherent redundancy that increases the signal-to-noise ratio as the square root of the number of sensors examined. The representative amount of each probe-type in the array was dependent on their initial stock solution concentration, and as other sequences of interest arise, new microsphere elements can be added to arrays without altering the existing detection capabilities. The oligonucleotide probe sequences hybridize to fluorescently-labeled, complementary DNA target solutions. Fiber optic DNA microarray research has included DNA-protein interaction profiles, microbial strain differentiation, non-labeled target interrogation with molecular beacons, and single cell-based assays. This biosensor array is proficient in DNA detection linked to specific disease states, single nucleotide polymorphism (SNP's) discrimination, and gene expression analysis. This array platform permits multiple detection formats, provides smaller feature sizes, and enables sensor design flexibility. High-density fiber optic microarray biosensors provide a fast

  9. High density plasma etching of magnetic devices

    NASA Astrophysics Data System (ADS)

    Jung, Kee Bum

    Magnetic materials such as NiFe (permalloy) or NiFeCo are widely used in the data storage industry. Techniques for submicron patterning are required to develop next generation magnetic devices. The relative chemical inertness of most magnetic materials means they are hard to etch using conventional RIE (Reactive Ion Etching). Therefore ion milling has generally been used across the industry, but this has limitations for magnetic structures with submicron dimensions. In this dissertation, we suggest high density plasmas such as ECR (Electron Cyclotron Resonance) and ICP (Inductively Coupled Plasma) for the etching of magnetic materials (NiFe, NiFeCo, CoFeB, CoSm, CoZr) and other related materials (TaN, CrSi, FeMn), which are employed for magnetic devices like magnetoresistive random access memories (MRAM), magnetic read/write heads, magnetic sensors and microactuators. This research examined the fundamental etch mechanisms occurring in high density plasma processing of magnetic materials by measuring etch rate, surface morphology and surface stoichiometry. However, one concern with using Cl2-based plasma chemistry is the effect of residual chlorine or chlorinated etch residues remaining on the sidewalls of etched features, leading to a degradation of the magnetic properties. To avoid this problem, we employed two different processing methods. The first one is applying several different cleaning procedures, including de-ionized water rinsing or in-situ exposure to H2, O2 or SF6 plasmas. Very stable magnetic properties were achieved over a period of ˜6 months except O2 plasma treated structures, with no evidence of corrosion, provided chlorinated etch residues were removed by post-etch cleaning. The second method is using non-corrosive gas chemistries such as CO/NH3 or CO2/NH3. There is a small chemical contribution to the etch mechanism (i.e. formation of metal carbonyls) as determined by a comparison with Ar and N2 physical sputtering. The discharge should be NH3

  10. High-density electroencephalography developmental neurophysiological trajectories.

    PubMed

    Dan, Bernard; Pelc, Karine; Cebolla, Ana M; Cheron, Guy

    2015-04-01

    Efforts to document early changes in the developing brain have resulted in the construction of increasingly accurate structural images based on magnetic resonance imaging (MRI) in newborn infants. Tractography diagrams obtained through diffusion tensor imaging have focused on white matter microstructure, with particular emphasis on neuronal connectivity at the level of fibre tract systems. Electroencephalography (EEG) provides a complementary approach with more direct access to brain electrical activity. Its temporal resolution is excellent, and its spatial resolution can be enhanced to physiologically relevant levels, through the combination of high-density recordings (e.g. by using 64 channels in newborn infants) and mathematical models (e.g. inverse modelling computation), to identify generators of different oscillation bands and synchrony patterns. The integration of functional and structural topography of the neonatal brain provides insights into typical brain organization, and the deviations seen in particular contexts, for example the effect of hypoxic-ischaemic insult in terms of damage, eventual reorganization, and functional changes. Endophenotypes can then be used for pathophysiological reasoning, management planning, and outcome measurements, and allow a longitudinal approach to individual developmental trajectories.

  11. Infrared imaging of high density protein arrays.

    PubMed

    De Meutter, Joëlle; Vandenameele, Julie; Matagne, André; Goormaghtigh, Erik

    2017-04-10

    We propose in this paper that protein microarrays could be analysed by infrared imaging in place of enzymatic or fluorescence labelling. This label-free method reports simultaneously a large series of data on the spotted sample (protein secondary structure, phosphorylation, glycosylation, presence of impurities, etc.). In the present work, 100 μm protein spots each containing about 100 pg protein were deposited to form high density regular arrays. Using arrays of infrared detectors, high resolution images could be obtained where each pixel of the image is in fact a full infrared spectrum. With microarrays, hundreds of experimental conditions can be tested easily and quickly, with no further labelling or chemistry of any kind. We describe how the noise present in the infrared spectra can be split into image noise and detector noise. We also detail how both types of noise can be most conveniently dealt with to generate very high quality spectra of less than 100 pg protein. Finally, the results suggest that the protein secondary structure is preserved during microarray building.

  12. Dark High Density Dipolar Liquid of Excitons.

    PubMed

    Cohen, Kobi; Shilo, Yehiel; West, Ken; Pfeiffer, Loren; Rapaport, Ronen

    2016-06-08

    The possible phases and the nanoscale particle correlations of two-dimensional interacting dipolar particles is a long-sought problem in many-body physics. Here we observe a spontaneous condensation of trapped two-dimensional dipolar excitons with internal spin degrees of freedom from an interacting gas into a high density, closely packed liquid state made mostly of dark dipoles. Another phase transition, into a bright, highly repulsive plasma, is observed at even higher excitation powers. The dark liquid state is formed below a critical temperature Tc ≈ 4.8 K, and it is manifested by a clear spontaneous spatial condensation to a smaller and denser cloud, suggesting an attractive part to the interaction which goes beyond the purely repulsive dipole-dipole forces. Contributions from quantum mechanical fluctuations are expected to be significant in this strongly correlated, long living dark liquid. This is a new example of a two-dimensional atomic-like interacting dipolar liquid, but where the coupling of light to its internal spin degrees of freedom plays a crucial role in the dynamical formation and the nature of resulting condensed dark ground state.

  13. Waste product profile: Polyethylene terephthalate

    SciTech Connect

    Miller, C.

    1996-02-01

    Polyethylene terephthalate (PET) is a plastic resin used primarily to make bottles. Soft drinks are the primary product packaged in PET. Salad dressing, peanut butter, and other household and consumer products also use PET bottles. PET is also used for film, sheeting for cups and food trays, ovenable trays, and other uses. PET is a relatively new packaging resin, first commercialized in the early `70s. Because it is an ``engineered`` resin, it is more expensive than commodity resins such as high-density polyethylene (HDPE). The primary market for recycled PET is the fiber industry, which uses PET for carpet fiber, sweaters and other clothing, and for other uses. Recycled PET can also be used for food and beverage containers. Export markets, particularly Asian countries, are becoming increasingly important.

  14. High density, uniformly distributed W/UO2 for use in Nuclear Thermal Propulsion

    NASA Astrophysics Data System (ADS)

    Tucker, Dennis S.; Barnes, Marvin W.; Hone, Lance; Cook, Steven

    2017-04-01

    An inexpensive, quick method has been developed to obtain uniform distributions of UO2 particles in a tungsten matrix utilizing 0.5 wt percent low density polyethylene. Powders were sintered in a Spark Plasma Sintering (SPS) furnace at 1600 °C, 1700 °C, 1750 °C, 1800 °C and 1850 °C using a modified sintering profile. This resulted in a uniform distribution of UO2 particles in a tungsten matrix with high densities, reaching 99.46% of theoretical for the sample sintered at 1850 °C. The powder process is described and the results of this study are given below.

  15. 14 CFR 93.123 - High density traffic airports.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 2 2014-01-01 2014-01-01 false High density traffic airports. 93.123... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES High Density Traffic Airports § 93.123 High density traffic airports. (a) Each of the following airports is designated as a...

  16. 14 CFR 93.123 - High density traffic airports.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 2 2013-01-01 2013-01-01 false High density traffic airports. 93.123... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES High Density Traffic Airports § 93.123 High density traffic airports. (a) Each of the following airports is designated as a...

  17. 14 CFR 93.123 - High density traffic airports.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 2 2012-01-01 2012-01-01 false High density traffic airports. 93.123... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES High Density Traffic Airports § 93.123 High density traffic airports. (a) Each of the following airports is designated as a...

  18. 14 CFR 93.123 - High density traffic airports.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 2 2011-01-01 2011-01-01 false High density traffic airports. 93.123... (CONTINUED) AIR TRAFFIC AND GENERAL OPERATING RULES SPECIAL AIR TRAFFIC RULES High Density Traffic Airports § 93.123 High density traffic airports. (a) Each of the following airports is designated as a...

  19. Compatibility and Decontamination of High-Density Polyethylene Exposed to Sulfur Mustard

    DTIC Science & Technology

    2014-05-01

    NAME(S) AND ADDRESS(ES) Director, ECBC, ATTN: RDCB-DPO- ML APG, MD 21010-5424 8. PERFORMING ORGANIZATION REPORT NUMBER ECBC-TR-1235 9...placed in the EDS .................................................................1 2. Task 1 coupons spiked with 2 mL of HD for storage...exploded pieces of UMSCs and approximately 1–2 g in mass, were placed in 40 mL volatile organic analysis (VOA) vials and weighed. Each coupon was

  20. Extrudate characteristics and morphology of styrene butadiene rubber/high density polyethylene blends

    NASA Astrophysics Data System (ADS)

    Jayasree, T. K.; Manuvel, Jayan

    2013-06-01

    When HDPE is added to SBR, the melt elasticity of the system gets reduced. The morphology of the extrudates of the blends has been found to be dependent on the shear rate. Dynamic crosslinking with DCP has been improved the processability of SBR/HDPE blends by reducing the melt elasticity of the system considerably.

  1. Natural fibre high-density polyethylene and lead oxide composites for radiation shielding

    NASA Astrophysics Data System (ADS)

    El-Sayed Abdo, A.; Ali, M. A. M.; Ismail, M. R.

    2003-03-01

    Study has been made of the radiation shielding provided by recycled agricultural fibre and industrial plastic wastes produced as composite materials. Fast neutron and gamma-ray spectra behind composites of fibre-plastic ( ρ = 1.373 g cm -3) and fibre-plastic-lead ( ρ = 2.756 g cm -3) have been measured using a collimated reactor beam and neutron-gamma spectrometer with a stilbene scintillator. The pulse shape discriminating technique based on the zero-cross-over method was used to discriminate between neutron and gamma-ray pulses. Slow neutron fluxes have been measured using a collimated reactor beam and BF 3 counter, leading to determination of the macroscopic cross-section ( Σ). The removal cross-sections ( ΣR) of fast neutrons have been determined from measured results and elemental composition of the composites. For gamma-rays, total linear attenuation coefficients ( μ) and total mass attenuation coefficients ( μ/ ρ) have been determined from use of the XCOM code and measured results. Reasonable agreement was found between measured and calculated results.

  2. Porous high-density polyethylene in facial reconstruction and revision rhinoplasty: a prospective cohort study

    PubMed Central

    2012-01-01

    Introduction Initial methods which used human tissues as reconstruction materials caused different problems including rejection, limited shapes and infection. In 1970s, PHDPE (Medpor®) was introduced by its exclusive advantageous including no donor site morbidity, easily shaped and the minimal foreign body reaction. Hereby, we report our experience of using Medpor® in facial reconstruction especially in frontal reconstruction and orbital rim with a large sample size. Methods This study was a prospective cohort study. Surgical techniques included using Medpor® in reconstruction of lamina papiracea (LP) (15 patients), frontal bone (15 patients), orbital rim (18 patients) and open rhinoplasty (8 patients). All interventions on LP were performed by endoscopic procedures. All frontal operations were carried out by bicoronal incision. In orbital defects, we used subciliary incision. Results From all 56 patients, 1 case had primitive neuroectodermal tumor (PNET) of maxillary sinus. In that case, reconstruction of inferior orbital rim was not successful and extrusion was occurred after radiotherapy. In rhinoplasty and other experiences no extrusion or infection were detected within the next 1 to 3 years of follow up. There were not any palpable and visible irregularities under the skin in our experiences. Conclusions In this study the patients did not experience any complications during the follow up periods and the satisfaction was remarkable. Gathering these data gives rise to future review studies which can provide more organized evidences for replacing classic reconstructive methods by the presented material. PMID:22642753

  3. [Analysis of high density porous polyethylene (Medpor) orbital implant in 266 cases].

    PubMed

    Cui, Hong-guang; Li, Hui-yan; Chen, Yan-hong

    2006-03-01

    To evaluate the postoperative complications, the appearance and motility in patients who underwent placement of Medpor orbital implant after enucleation, or secondary implantion. A retrospective study was carried out on the 266 cases in whom a Medpor orbital implant was implanted from 2001 to 2004. All the cases were followed up from 3 to 26 months. A total of 23 in 266 (8.6%) cases had documented postoperative complications: inflammatory granuloma in 2 cases (0.8%), and moderate or severe ptosis in 4 cases (1.5%), and remained upper eyelid notch with mild ptosis in 8 cases (3.0%), and lower eyelid laxity in 2 cases (0.8%). In 5 cases (1.9%), implant exposure developed: 3 cases were resolved with conservative therapy, and 2 cases with surgical revision of the socket. 2 cases experienced persistent pyogenic discharge in conjunctival sac, and the implant was took out because the discharge couldn't control with local and systemic antibiotic therapy. The motility is excellent in 148 cases and good in 11 cases after the primary obital implant, and excellent in 36 cases and good in 68 cases and bad in 3 case after the secondary implant. The difference between the primary and the secondary obital implant is obvious. It is considered that Medpor orbital implant is a good method of ocular plasty. Although there are some mild postoperative complications, but those can be resolved with conservative therapy or surgical revision. Medpor orbital implant has good histocompatibility, and the operative processes are convenient. Patients are satisfied with appearance and motility. So the Medpor orbital implant is one of the best selection in ocular socket plasty.

  4. Loading-Strain Equivalence Between Thermomechanical, Creep, and Tensile Tests: High Density Polyethylene

    DTIC Science & Technology

    1994-07-01

    MAX) in tLo = tc in the T range 0 K < T < T(Melt). According to Billmeyer (37), the total strain, composed of elastic and viscoelastic components in a...Properties of Materials, p 264 (Figs 8 through 44), and p. 306 (Question 4), MacMillan, NY, (1971). 37. FW. Billmeyer , Jr., Textbook of Polymer Science

  5. High Density Lipoprotein Metabolism in Man

    PubMed Central

    Blum, Conrad B.; Levy, Robert I.; Eisenberg, Shlomo; Hall, Marshall; Goebel, Robert H.; Berman, Mones

    1977-01-01

    The turnover of 125I-high density lipoprotein (HDL) was examined in a total of 14 studies in eight normal volunteers in an attempt to determine the metabolic relationship between apolipoproteins A-I (apoA-I) and A-II (apoA-II) of HDL and to define further some of the determinants of HDL metabolism. All subjects were first studied under conditions of an isocaloric balanced diet (40% fat, 40% carbohydrate). Four were then studied with an 80% carbohydrate diet, and two were studied while receiving nicotinic acid (1 g three times daily) and ingesting the same isocaloric balanced diet. The decay of autologous 125I-HDL and the appearance of urinary radioactivity were followed for at least 2 wk in each study. ApoA-I and apoA-II were isolated by Sephadex G-200 chromatography from serial plasma samples in each study. The specific activities of these peptides were then measured directly. It was found that the decay of specific activity of apoA-I and apoA-II were parallel to one another in all studies. The mean half-life of the terminal portion of decay was 5.8 days during the studies with a balanced diet. Mathematical modeling of the decay of plasma radioactivity and appearance of urinary radioactivity was most consistent with a two-compartment model. One compartment is within the plasma and exchanges with a nonplasma component. Catabolism occurs from both of these compartments. With a balanced isocaloric diet, the mean synthetic rate for HDL protein was 8.51 mg/kg per day. HDL synthesis was not altered by the high carbohydrate diet and was only slightly decreased by nicotinic acid treatment. These perturbations had effects on HDL catabolic pathways that were reciprocal in many respects. With an 80% carbohydrate diet, the rate of catabolism from the plasma compartment rose by a mean of 39.1%; with nicotinic acid treatment, it fell by 42.2%. Changes in the rate of catabolism from the second compartment were generally opposite those in the rate of catabolism from the plasma

  6. Laser Direct Routing for High Density Interconnects

    NASA Astrophysics Data System (ADS)

    Moreno, Wilfrido Alejandro

    Diffused Link. A high density Laser Vertical Link with resistance values below 10 ohms was developed, studied and tested using design of experiment methodologies. The vertical link offers excellent advantages in the area of quick prototyping of electronic circuits, but even more important, due to having similar characteristics to a foundry produced via, it gives quick transfer from the prototype system verification stage to the mass production stage.

  7. Development of Infrared Welder for Sealing of Polyethylene TRU-Waste Containers

    SciTech Connect

    Milling, R.B.

    1999-06-08

    Engineers at the Savannah River Technology Center have successfully performed infrared welding of High Density Polyethylene test specimens to prove the feasibility of using the infrared welding process in the HANDSS-55-TRU-Waste Repackaging Module.

  8. Development of Infrared Welder for Sealing of Polyethylene TRU-Waste Containers

    SciTech Connect

    Milling, R.B.

    1999-06-08

    Engineers at the Savannah River Technology Center have successfully performed infrared welding of High Density Polyethylene test specimens to prove the feasibility of using the infrared welding process in the HANDSS-55-TRU-Waste Repackaging Module.

  9. The mechanical properties of density graded hemp/polyethylene composites

    NASA Astrophysics Data System (ADS)

    Dauvegis, Raphaël; Rodrigue, Denis

    2015-05-01

    In this work, the production and mechanical characterization of density graded biocomposites based on high density polyethylene and hemp fibres was performed. The effect of coupling agent addition (maleated polyethylene) and hemp content (0-30%) was studied to determine the effect of hemp distribution (graded content) inside the composite (uniform, linear, V and Λ). Tensile and flexural properties are reported to compare the structures, especially in terms of their stress-strain behaviors under tensile loading.

  10. Relation between the High Density Phase and the Very-High Density Phase of Amorphous Solid Water

    NASA Astrophysics Data System (ADS)

    Giovambattista, Nicolas; Stanley, H. Eugene; Sciortino, Francesco

    2005-03-01

    It has been suggested that high-density amorphous (HDA) ice is a structurally arrested form of high-density liquid (HDL) water, while low-density amorphous ice is a structurally arrested form of low-density liquid (LDL) water. Recent experiments and simulations have been interpreted to support the possibility of a second distinct high-density structural state, named very high-density amorphous (VHDA) ice, questioning the LDL-HDL hypothesis. We test this interpretation using extensive computer simulations and find that VHDA is a more stable form of HDA and that, in fact, VHDA should be considered as the amorphous ice of the quenched HDL.

  11. 14 CFR 93.123 - High density traffic airports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 2 2010-01-01 2010-01-01 false High density traffic airports. 93.123 Section 93.123 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... § 93.123 High density traffic airports. (a) Each of the following airports is designated as a high...

  12. Study of the photo-detection efficiency of FBK High-Density silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Zappalà, G.; Acerbi, F.; Ferri, A.; Gola, A.; Paternoster, G.; Regazzoni, V.; Zorzi, N.; Piemonte, C.

    2016-11-01

    This work presents a study of the factors contributing to the Photo-Detection Efficiency of Silicon Photomultipliers (SiPMs): Quantum Efficiency, Triggering Probability and Fill Factor. Two different SiPM High-Density technologies are tested, NUV-HD, based on n-on-p junction, and RGB-HD, based on p-on-n junction, developed at FBK, Trento. The quantum efficiency was measured on photodiodes produced along with the SiPMs. The triggering probability, as a function of wavelength and bias voltage, was measured on circular Single Photon Avalanche Diodes (SPADs) with 100% fill factor. Square SPADs, having the same layout of single SiPM cells, were studied to measure the effective fill factor and compare it to the nominal value. The comparison of the circular and square SPADs allows to get the transition region size between the effective active area of the cell and the one defined by the layout.

  13. Small-Scale Production of High-Density Dry Ice: A Variant Combination of Two Classic Demonstrations

    ERIC Educational Resources Information Center

    Flowers, Paul A.

    2009-01-01

    Easily recoverable, thumb-sized pieces of high-density dry ice are conveniently produced by deposition of carbon dioxide within a test tube submerged in liquid nitrogen. A carbon dioxide-filled balloon sealed over the mouth of the test tube serves as a gas reservoir, and further permits a dramatic demonstration of both the gas-to-solid phase…

  14. Small-Scale Production of High-Density Dry Ice: A Variant Combination of Two Classic Demonstrations

    ERIC Educational Resources Information Center

    Flowers, Paul A.

    2009-01-01

    Easily recoverable, thumb-sized pieces of high-density dry ice are conveniently produced by deposition of carbon dioxide within a test tube submerged in liquid nitrogen. A carbon dioxide-filled balloon sealed over the mouth of the test tube serves as a gas reservoir, and further permits a dramatic demonstration of both the gas-to-solid phase…

  15. High-density through-wafer copper via array in insulating glass mold using reflow process

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Woo; Lee, Seung-Ki; Park, Jae-Hyoung

    2015-04-01

    A high-density through-wafer vertical copper via array in insulating glass interposer is demonstrated. The glass reflow and bottom-up filling copper electroplating process enables fabrication of a vertical through-wafer copper via array with high aspect ratio and high density. The minimum diameter of the copper vias and the gaps in between are 20 and 10 µm, respectively. Three failures among one hundred measurement points were detected within a 1 cm2 area of the via array, and the resistance of the 20-µm-diameter copper via was measured to be 153 ± 23 mΩ using the four-probe method. The optical transmittance and RF performance of the reflowed glass substrate were compared with those of bare glass. The reliability of the copper via in harsh environments was evaluated through thermal shock and pressure cooker tests.

  16. Poly(ethylene imine)-based granular sorbents by a new process of templated gel-filling. High capacity and selectivity of copper sorption in acidic and alkaline media

    SciTech Connect

    Chanda, M.; Rempel, G.L.

    1995-08-01

    A new process has been developed for making granular gel-type sorbents from chelating resins using metal ion as template. Named as templated gel-filling, the process uses the chosen metal as templating host ion on high-surface-area silica to build a templated gel layer from a solution of the chelating resin in a suitable solvent in which the resin is soluble but its metal complex is insoluble. After cross-linking the templated gel layer, the silica support is removed by alkali to produce a hollow shell of the templated gel. The shells are then soaked in a concentrated aqueous solution of the same metal ion and suspended in the same resin solution to afford gel-filling. The shells thus filled with metal-templated gel are treated with cross-linking agent, followed by acid to remove the template ion and activate the resin for metal sorption. Poly(ethyleneimine) and its partially ethylated derivative have been used to produce granular gel-type sorbents by this process, with Cu(II) as the template ion. These sorbents are found to offer high capacity and selectivity for copper over nickel, cobalt, and zinc in both acidic and alkaline media. Containing a relatively high fraction of imbibed water, the sorbents exhibit markedly enhanced rate behavior, in both sorption and stripping.

  17. The radiation improvement of polyethylene prostheses. A preliminary study.

    PubMed

    Grobbelaar, C J; du Plessis, T A; Marais, F

    1978-08-01

    The radiation crosslinking of high-density polyethylene prostheses was investigated over a wide range of doses in the presence and absence of gaseous crosslinking agents. It was found that in the bulk polymer the crosslinking pattern is completely different from the homogeneous crosslinking that occurs in polymer films. The presence of crosslinking agents causes highly crosslinked polymer to be formed on the surface while the bulk of the polymer is largely unaffected--which is explained in terms of diffusion phenomena. This surface crosslinking has a profound effect on the mechanical properties of the prostheses and restricts cold flow and deformation of the polymer without sacrificing the excellent abrasion-resistance properties of the polyethylene when subjected to high pressures. Based on this research a number of high-density polyethylene knee prostheses have been radiation-crosslinked and the results in vitro appear to be very promising.

  18. High-density lipoprotein cholesterol: current perspective for clinicians.

    PubMed

    Whayne, Thomas F

    2009-01-01

    High-density lipoproteins are regarded as ''good guys'' but not always. Situations involving high-density lipoproteins are discussed and medication results are considered. Clinicians usually consider high-density lipoprotein cholesterol. Nicotinic acid is the best available medication to elevate high-density lipoprotein cholesterol and this appears beneficial for cardiovascular risk. The major problem with nicotinic acid is that many patients do not tolerate the associated flushing. Laropiprant decreases this flushing and has an approval in Europe but not in the United States. The most potent medications for increasing high-density lipoprotein cholesterol are cholesteryl ester transfer protein inhibitors. The initial drug in this class, torcetrapib, was eliminated by excess cardiovascular problems. Two newer cholesteryl ester transfer protein inhibitors, R1658 and anacetrapib, initially appear promising. High-density lipoprotein cholesterol may play an important role in improving cardiovascular risk in the 60% of patients who do not receive cardiovascular mortality/morbidity benefit from low-density lipoproteins reduction by statins.

  19. Effects of extractives on some properties of bagasse/high density polypropylene composite.

    PubMed

    Sheshmani, Shabnam

    2013-04-15

    In this study, the effects of two variable parameters, namely the extractives and filler loading level, on the physical properties of composites were examined. Composites based on high density polyethylene (HDPE), bagasse flour (BF) as filler were made by injection molding. In order to increase the interphase adhesion, maleic anhydride grafted polyethylene (MAPE) was added as a coupling agent to all the composites studied. Three different solvents, ethanol-benzene, 1% NaOH and hot-water, were used to remove extractives. Physical properties, namely, water absorption (WA) and thickness swelling (TS) were investigated for a long period. At same filler loading, composites made with extracted bagasse had higher WA and TS values. In addition, the TS of samples showed a similar pattern to the water uptake data. The difference in WA between extracted and unextracted composites is due to blocking of -OH groups by extractives. The results also showed that as the BF content was increased, significant increase in WA and TS occurred. Statistical analysis confirmed that the effects of both variables and their interactions on the WA and TS properties were significant at 1% confidence level.

  20. Improving the circular economy via hydrothermal processing of high-density waste plastics.

    PubMed

    Helmer Pedersen, Thomas; Conti, Federica

    2017-10-01

    Rising environmental concerns on climate changes are causing an increasing attention on circular economies. The plastic economy, in particular, is in focus due to the accelerating consumption of plastics, mainly derived from virgin feedstock, combined with the lack of plastic recycling strategies. This work presents a novel outlook on the potential of using supercritical hydrothermal processing of waste plastic fractions for tertiary recycling. The study investigates hydrothermal processing of nine different, high-density types of plastics into original resin monomers and other value-added chemical compounds. The outlook presents conversion yields, carbon balances, and chemical details on the products obtained. It is found that all the investigated resins are prone to hydrothermal treatment, and that high yields of monomers and high value compounds (up to nearly 100%), suitable for chemicals and fuels applications, can be obtained. For instance, for polycarbonate, styrene-butadiene, poly(lactic acid), poly(ethylene terephthalate), and poly(butylene terephthalate), original monomeric compounds can be reclaimed for manufacturing new resins. The promising results presented demonstrate that hydrothermal processing of high-density plastics is a prospective technology for increasing the circularity of the plastic economy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Filled Craters

    NASA Image and Video Library

    2006-05-11

    This MOC image shows adjacent impact craters located north-northwest of the Acheron Fossae region of Mars. The two craters are of similar size and formed by meteor impacts. However, one is much more filled than the other, indicating that it is older

  2. High-density monolayers of metal complexes: preparation and catalysis.

    PubMed

    Hara, Kenji; Sawamura, Masaya; Fukuoka, Atsushi

    2014-10-01

    Catalysts are one of the key materials for realizing a sustainable society. However, we may encounter problematic cases where conventional catalyst systems cannot provide effective solutions. We thus believe that the establishment of novel methods of catalyst preparation is currently necessary. Utilization of high-density monolayers of molecular metal complexes is our strategy, and we expect that this methodology will enable facile and systematic screening of unique and efficient catalysts. This Personal Account describes our challenges to establish such an immature method in catalyst preparation as well as the related background and perspective. Preparation and catalysis by high-density monolayers of Rh complexes with N-heterocyclic carbene, structurally compact phosphine and diisocyanide ligands on gold surfaces are presented. The catalytic application of a high-density Pd-bisoxazoline complex prepared on a single-crystal silicon surface is also shown. Uniquely high catalyst turnover numbers and high chemoselectivities were observed with these catalyst systems.

  3. High-density scintillating glasses for a proton imaging detector

    NASA Astrophysics Data System (ADS)

    Tillman, I. J.; Dettmann, M. A.; Herrig, V.; Thune, Z. L.; Zieser, A. J.; Michalek, S. F.; Been, M. O.; Martinez-Szewczyk, M. M.; Koster, H. J.; Wilkinson, C. J.; Kielty, M. W.; Jacobsohn, L. G.; Akgun, U.

    2017-06-01

    High-density scintillating glasses are proposed for a novel proton-imaging device that can improve the accuracy of the hadron therapy. High-density scintillating glasses are needed to build a cost effective, compact calorimeter that can be attached to a gantry. This report summarizes the study on Europium, Terbium, and Cerium-doped scintillating glasses that were developed containing heavy elements such as Lanthanum, Gadolinium, and Tungsten. The density of the samples reach up to 5.9 g/cm3, and their 300-600 nm emission overlaps perfectly with the peak cathode sensitivity of the commercial photo detectors. The developed glasses do not require any special quenching and can be poured easily, which makes them a good candidate for production in various geometries. Here, the glass making conditions, preliminary tests on optical and physical properties of these scintillating, high-density, oxide glasses developed for a novel medical imaging application are reported.

  4. Emerging strategies for increasing high-density lipoprotein.

    PubMed

    Forrester, James S; Shah, Prediman K

    2006-12-01

    High-density lipoprotein cholesterol is a potent and independent epidemiologic risk factor and is a proved antiatherosclerotic agent in animal models of atherosclerosis, acting through the principal mechanisms of accelerating cholesterol efflux and inhibiting oxidation and inflammation. Lifestyle modification increases serum levels by 5% to 15%, whereas niacin, the drug most widely used to increase high-density lipoprotein cholesterol, increases it by 25% to 35% at the highest doses. This review examines the potent methods of increasing high-density lipoprotein and/or enhancing reverse cholesterol transport, including cholesterol ester transfer protein inhibitors, apolipoprotein A-I Milano, D4F, the dual peroxisome proliferator-activated receptor agonists, and rimonabant, that are now in clinical trials. In conclusion, these new agents, used alone or in combination with existing therapies, carry the potential to markedly reduce the incidence of new coronary disease and cardiac events in this decade.

  5. High density semiconductor nanodots by direct laser fabrication

    NASA Astrophysics Data System (ADS)

    Haghizadeh, Anahita; Yang, Haeyeon

    2016-03-01

    We report a direct method of fabricating high density nanodots on the GaAs(001) surfaces using laser irradiations on the surface. Surface images indicate that the large clumps are not accompanied with the formation of nanodots even though its density is higher than the critical density above which detrimental large clumps begin to show up in the conventional Stranski-Krastanov growth technique. Atomic force microscopy is used to image the GaAs(001) surfaces that are irradiated by high power laser pulses interferentially. The analysis suggests that high density quantum dots be fabricated directly on semiconductor surfaces.

  6. High-density carbon ablator experiments on the National Ignition Facilitya)

    SciTech Connect

    MacKinnon, A. J.; Meezan, N. B.; Ross, J. S.; Le Pape, S.; Berzak Hopkins, L.; Divol, L.; Ho, D.; Milovich, J.; Pak, A.; Ralph, J.; Döppner, T.; Patel, P. K.; Thomas, C.; Tommasini, R.; Haan, S.; MacPhee, A. G.; McNaney, J.; Caggiano, J.; Hatarik, R.; Bionta, R.; Ma, T.; Spears, B.; Rygg, J. R.; Benedetti, L. R.; Town, R. P. J.; Bradley, D. K.; Dewald, E. L.; Fittinghoff, D.; Jones, O. S.; Robey, H. R.; Moody, J. D.; Khan, S.; Callahan, D. A.; Hamza, A.; Biener, J.; Celliers, P. M.; Braun, D. G.; Erskine, D. J.; Prisbrey, S. T.; Wallace, R. J.; Kozioziemski, B.; Dylla-Spears, R.; Sater, J.; Collins, G.; Storm, E.; Hsing, W.; Landen, O.; Atherton, J. L.; Lindl, J. D.; Edwards, M. J.; Frenje, J. A.; Gatu-Johnson, M.; Li, C. K.; Petrasso, R.; Rinderknecht, H.; Rosenberg, M.; Séguin, F. H.; Zylstra, A.; Knauer, J. P.; Grim, G.; Guler, N.; Merrill, F.; Olson, R.; Kyrala, G. A.; Kilkenny, J. D.; Nikroo, A.; Moreno, K.; Hoover, D. E.; Wild, C.; Werner, E.

    2014-05-01

    High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has a higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results in a thinner ablator with a larger inner radius for a given capsule scale. This leads to higher x-ray absorption and shorter laser pulses compared to equivalent CH designs. This paper will describe a series of experiments carried out to examine the feasibility of using HDC as an ablator using both gas filled hohlraums and lower density, near vacuum hohlraums. These experiments have shown that deuterium (DD) and deuterium-tritium gas filled HDC capsules driven by a hohlraum filled with 1.2 mg/cc He gas, produce neutron yields a factor of 2× higher than equivalent CH implosions, representing better than 50% Yield-over-Clean (YoC). In a near vacuum hohlraum (He = 0.03 mg/cc) with 98% laser-to-hohlraum coupling, such a DD gas-filled capsule performed near 1D expectations. A cryogenic layered implosion version was consistent with a fuel velocity = 410 ± 20 km/s with no observed ablator mixing into the hot spot.

  7. High-density carbon ablator experiments on the National Ignition Facility

    SciTech Connect

    MacKinnon, A. J. Meezan, N. B.; Ross, J. S.; Le Pape, S.; Berzak Hopkins, L.; Divol, L.; Ho, D.; Milovich, J.; Pak, A.; Ralph, J.; Döppner, T.; Patel, P. K.; Thomas, C.; Tommasini, R.; Haan, S.; MacPhee, A. G.; McNaney, J.; Caggiano, J.; Hatarik, R.; Bionta, R.; and others

    2014-05-15

    High Density Carbon (HDC) is a leading candidate as an ablator material for Inertial Confinement Fusion (ICF) capsules in x-ray (indirect) drive implosions. HDC has a higher density (3.5 g/cc) than plastic (CH, 1 g/cc), which results in a thinner ablator with a larger inner radius for a given capsule scale. This leads to higher x-ray absorption and shorter laser pulses compared to equivalent CH designs. This paper will describe a series of experiments carried out to examine the feasibility of using HDC as an ablator using both gas filled hohlraums and lower density, near vacuum hohlraums. These experiments have shown that deuterium (DD) and deuterium-tritium gas filled HDC capsules driven by a hohlraum filled with 1.2 mg/cc He gas, produce neutron yields a factor of 2× higher than equivalent CH implosions, representing better than 50% Yield-over-Clean (YoC). In a near vacuum hohlraum (He = 0.03 mg/cc) with 98% laser-to-hohlraum coupling, such a DD gas-filled capsule performed near 1D expectations. A cryogenic layered implosion version was consistent with a fuel velocity = 410 ± 20 km/s with no observed ablator mixing into the hot spot.

  8. High density constraint on the entropy instability. [with nonisothermal effect

    NASA Technical Reports Server (NTRS)

    Hudson, M. K.; Kennel, C. F.

    1974-01-01

    The entropy instability squared is a nonisothermal effect which is eliminated by parallel ion pressure at high densities (k sub z lambda sub e 1/2 sq root of m/M), reducing previous growth rate estimates and the range of unstable parameters.

  9. High density packaging and interconnect of massively parallel image processors

    NASA Technical Reports Server (NTRS)

    Carson, John C.; Indin, Ronald J.

    1991-01-01

    This paper presents conceptual designs for high density packaging of parallel processing systems. The systems fall into two categories: global memory systems where many processors are packaged into a stack, and distributed memory systems where a single processor and many memory chips are packaged into a stack. Thermal behavior and performance are discussed.

  10. Probabilistic Fatigue Life Analysis of High Density Electronics Packaging

    NASA Technical Reports Server (NTRS)

    Moore, N. R.; Kolawa, E. A.; Sutharshana, S.; Newlin, L. E.; Creager, M.

    1996-01-01

    The fatigue of thin film metal interconnections in high density electronics packaging subjected to thermal cycling has been evaluated using a probabilistic fracture mechanics methodology. This probabilistic methodology includes characterization of thin film stress using an experimentally calibrated finite element model and simulation of flaw growth in the thin films using a stochastic crack growth model.

  11. High Density Polymer-Based Integrated Electgrode Array

    DOEpatents

    Maghribi, Mariam N.; Krulevitch, Peter A.; Davidson, James Courtney; Hamilton, Julie K.

    2006-04-25

    A high density polymer-based integrated electrode apparatus that comprises a central electrode body and a multiplicity of arms extending from the electrode body. The central electrode body and the multiplicity of arms are comprised of a silicone material with metal features in said silicone material that comprise electronic circuits.

  12. Heat map visualization of high-density clinical chemistry data.

    PubMed

    Auman, J Todd; Boorman, Gary A; Wilson, Ralph E; Travlos, Gregory S; Paules, Richard S

    2007-10-22

    Clinical chemistry data are routinely generated as part of preclinical animal toxicity studies and human clinical studies. With large-scale studies involving hundreds or even thousands of samples in multiple treatment groups, it is currently difficult to interpret the resulting complex, high-density clinical chemistry data. Accordingly, we conducted this study to investigate methods for easy visualization of complex, high-density data. Clinical chemistry data were obtained from male rats each treated with one of eight different acute hepatotoxicants from a large-scale toxicogenomics study. The raw data underwent a Z-score transformation comparing each individual animal's clinical chemistry values to that of reference controls from all eight studies and then were visualized in a single graphic using a heat map. The utility of using a heat map to visualize high-density clinical chemistry data was explored by clustering changes in clinical chemistry values for >400 animals. A clear distinction was observed in animals displaying hepatotoxicity from those that did not. Additionally, while animals experiencing hepatotoxicity showed many similarities in the observed clinical chemistry alterations, distinct differences were noted in the heat map profile for the different compounds. Using a heat map to visualize complex, high-density clinical chemistry data in a single graphic facilitates the identification of previously unrecognized trends. This method is simple to implement and maintains the biological integrity of the data. The value of this clinical chemistry data transformation and visualization will manifest itself through integration with other high-density data, such as genomics data, to study physiology at the systems level.

  13. A tale of two electrons: Correlation at high density

    NASA Astrophysics Data System (ADS)

    Loos, Pierre-François; Gill, Peter M. W.

    2010-11-01

    We review our recent progress in the determination of the high-density correlation energy E in two-electron systems. Several two-electron systems are considered, such as the well known helium-like ions (helium), and the Hooke's law atom (hookium). We also present results regarding two electrons on the surface of a sphere (spherium), and two electrons trapped in a spherical box (ballium). We also show that, in the large-dimension limit, the high-density correlation energy of two opposite-spin electrons interacting via a Coulomb potential is given by E˜-1/(8D2) for any radial external potential V(r), where D is the dimensionality of the space. This result explains the similarity of E in the previous two-electron systems for D=3.

  14. Noise reduction in muon tomography for detecting high density objects

    NASA Astrophysics Data System (ADS)

    Benettoni, M.; Bettella, G.; Bonomi, G.; Calvagno, G.; Calvini, P.; Checchia, P.; Cortelazzo, G.; Cossutta, L.; Donzella, A.; Furlan, M.; Gonella, F.; Pegoraro, M.; Rigoni Garola, A.; Ronchese, P.; Squarcia, S.; Subieta, M.; Vanini, S.; Viesti, G.; Zanuttigh, P.; Zenoni, A.; Zumerle, G.

    2013-12-01

    The muon tomography technique, based on multiple Coulomb scattering of cosmic ray muons, has been proposed as a tool to detect the presence of high density objects inside closed volumes. In this paper a new and innovative method is presented to handle the density fluctuations (noise) of reconstructed images, a well known problem of this technique. The effectiveness of our method is evaluated using experimental data obtained with a muon tomography prototype located at the Legnaro National Laboratories (LNL) of the Istituto Nazionale di Fisica Nucleare (INFN). The results reported in this paper, obtained with real cosmic ray data, show that with appropriate image filtering and muon momentum classification, the muon tomography technique can detect high density materials, such as lead, albeit surrounded by light or medium density material, in short times. A comparison with algorithms published in literature is also presented.

  15. Advanced short haul aircraft for high density markets

    NASA Technical Reports Server (NTRS)

    Galloway, T. L.

    1977-01-01

    The short haul (less than 500 miles) passenger enplanements represent about 50% of the total domestic enplanements. These can be distinguished by the annual passenger flow for a given city pair and classified into low, medium and high densiy markets. NASA studies have investigated various advanced short haul aircraft concepts that have potential application in these three market areas. Although advanced operational techniques impact all market densities, advanced vehicle design concepts such as RTOL, STOL and VTOL have the largest impact in the high density markets. This paper summarizes the results of NASA sponsored high density short haul air transportation systems studies and briefly reviews NASA sponsored advanced VTOL conceptual aircraft design studies. Trends in vehicle characteristics and operational requirements will be indicated in addition to economic suitability and impact on the community.

  16. Advanced short haul systems in high density markets

    NASA Technical Reports Server (NTRS)

    Galloway, T. L.

    1975-01-01

    The design requirements, performance, economics, and noise aspects of STOL and VTOL conceptual aircraft developed for short haul air transportation are reviewed, along with the characteristics of areas of high-density annual passenger flow in which the aircraft are intended to operate. It is shown that aircraft of 100 to 200 passenger capacity provide the best return on investment in high density markets. The various STOL propulsive lift concepts have the same general trends with field length; their wing loadings are 20 to 30 pounds per square foot higher than the nonpropulsive lift concepts. A comparison of the aircraft under consideration shows that no one aircraft concept will be optimum for all future operational environments.

  17. A Coupled Plasma-Sheath Model for High Density Sources

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindan, T. R.; Meyyappan, M.

    2000-01-01

    High density, low pressure plasmas are used for etching and deposition in microelectronics fabrication processes. The process characteristics are strongly determined by the ion energy distribution (IED) and the ion flux arriving at the substrate that are responsible for desorption of etch products and neutral dissociation at the surface. The ion flux and energy are determined by a self- consistent modeling of the bulk plasma, where the ions and the neutral radicals are produced, and the sheath, where the ions are accelerated. Due to their widely different time scales, it is a formidable task to self-consistently resolve non-collisional sheath in a high density bulk plasma model. In this work, we first describe a coupled plasma-sheath model that attempts to resolve the non-collisional sheath in a reactor scale model. Second, we propose a semianalytical radio frequency (RF) sheath model to improve ion dynamics.

  18. PREPARATION OF HIGH-DENSITY THORIUM OXIDE SPHERES

    DOEpatents

    McNees, R.A. Jr.; Taylor, A.J.

    1963-12-31

    A method of preparing high-density thorium oxide spheres for use in pellet beds in nuclear reactors is presented. Sinterable thorium oxide is first converted to free-flowing granules by means such as compression into a compact and comminution of the compact. The granules are then compressed into cubes having a density of 5.0 to 5.3 grams per cubic centimeter. The cubes are tumbled to form spheres by attrition, and the spheres are then fired at 1250 to 1350 deg C. The fired spheres are then polished and fired at a temperature above 1650 deg C to obtain high density. Spherical pellets produced by this method are highly resistant to mechanical attrition hy water. (AEC)

  19. Origins and impacts of high-density symmetry energy

    NASA Astrophysics Data System (ADS)

    Li, Bao-An

    2017-06-01

    What is nuclear symmetry energy? Why is it important? What do we know about it? Why is it so uncertain especially at high densities? Can the total symmetry energy or its kinetic part be negative? What are the effects of three-body and/or tensor force on symmetry energy? How can we probe the density dependence of nuclear symmetry energy with terrestrial nuclear experiments? What observables of heavy-ion reactions are sensitive to the high-density behavior of nuclear symmetry energy? How does the symmetry energy affect properties of neutron stars, gravitational waves and our understanding about the nature of strong-field gravity? In this lecture, we try to answer these questions as best as we can based on some of our recent work and/or understanding of research done by others. This note summarizes the main points of the lecture.

  20. Equation of State for a High-Density Glass

    NASA Astrophysics Data System (ADS)

    Mattsson, A. E.

    2004-07-01

    Properties of relevance for the equation of state for a high-density glass are discussed. We review the effects of failure waves, comminuted phase, and compaction on the validity of the Mie-Grüneisen EOS. The specific heat and the Grüneisen parameter at standard conditions for a ρ0 = 5.085 g/cm3 glass ("Glass A") is then estimated to be 522 mJ/g/K and 0.1 - 0.3, respectively. The latter value is substantially smaller than the value of 2.1751 given in the SESAME tables for a high-density glass with ρ0 = 5.46 g/cm3. The present unusual value of the Grüneisen parameter is confirmed from the volume dependence determined from fitting the Mie-Grüneisen EOS to shock data in Ref. [2].

  1. Equation of state for a high-density glass.

    SciTech Connect

    Mattsson, Ann Elisabet

    2003-07-01

    Properties of relevance for the equation of state for a high-density glass are discussed. We review the effects of failure waves, comminuted phase, and compaction on the validity of the Mie-Grueneisen EOS. The specific heat and the Grueneisen parameter at standard conditions for a {rho}{sub 0} = 5.085 g/cm{sup 3} glass ('Glass A') is then estimated to be 522 mJ/g/K and 0.1-0.3, respectively. The latter value is substantially smaller than the value of 2.1751 given in the SESAME tables for a high-density glass with {rho}{sub 0} = 5.46 g/cm{sup 3}. The present unusual value of the Grueneisen parameter is confirmed from the volume dependence determined from fitting the Mie-Grueneisen EOS to shock data in Ref. [2].

  2. Fabrication of very high density fuel pellets of thorium dioxide

    NASA Astrophysics Data System (ADS)

    Shiratori, Tetsuo; Fukuda, Kosaku

    1993-06-01

    Very high density ThO 2 pellets were prepared without binders and lubricants from the ThO 2 powder originated by the thorium oxalate, which was aimed to simplify the fabrication process by skipping a preheat treatment. The as-received ThO 2 powder with a surface area of 4.56 m 2/g was ball-milled up to about 9 m 2/g in order to increase the green pellet density as high as possible. Both of the single-sided and the double-sided pressing were tested in the range from 2 to 5 t/cm 2 in the green pellet formation. Sintering temperature was such low as 1550°C. The pellet prepared in this experiment had a very high density in the range from about 96 to 98% TD without any cracks, in which a difference of the pellet density was not recognized in the single-sided pressing methods.

  3. Heat Map Visualization of High-Density Clinical Chemistry Data

    PubMed Central

    Auman, J. Todd; Boorman, Gary A.; Wilson, Ralph E.; Travlos, Gregory S.; Paules, Richard S.

    2009-01-01

    Clinical chemistry data are routinely generated as part of preclinical animal toxicity studies and human clinical studies. With large-scale studies involving hundreds or even thousands of samples in multiple treatment groups, it is currently difficult to interpret the resulting complex, high-density clinical chemistry data. Clinical chemistry data were obtained from male rats each treated with one of eight different acute hepatotoxicants from a large-scale toxicogenomics study. The raw data underwent a Z-score transformation comparing each individual animal’s clinical chemistry values to that of reference controls from all eight studies and then visualized in a single graphic using a heat map. The utility of using a heat map to visualize high density clinical chemistry data was explored by clustering the changes in clinical chemistry values for over 400 animals. Clustering of the animals on clinical chemistry changes resulted in a clear distinction of the animals displaying hepatotoxicity from those that did not. Additionally, while animals experiencing hepatotoxicity showed many similarities in the observed clinical chemistry alterations, distinct differences were noted in the heat map profile for the different compounds. Using a heat map to visualize complex, high-density clinical chemistry data in a single graphic facilitates the identification of previously unrecognized trends. This method is simple to implement and maintains the biological integrity of the data. The value of this clinical chemistry data transformation and visualization will manifest itself through the integration with other high-density data, such as genomics data, to study physiology at the systems level. PMID:17652165

  4. Allotypy of High Density Lipoprotein of Rabbit Serum

    PubMed Central

    Berg, Kåre; Boman, Helge; Torsvik, Harald; Walker, Suzanne M.

    1971-01-01

    A common antigenic polymorphism of high density lipoprotein (HDL) in rabbit serum is described. The presence or absence of an antigen termed Hl 1 appears to be controlled by autosomal dominant inheritance. The polymorphism should be a useful tool in the study of serum lipoproteins, particularly since genetic polymorphisms within the low density lipoprotein are already known in several species. The Hl polymorphism may make the rabbit more useful for model studies of serum lipoproteins in health and disease. Images PMID:4995822

  5. High-Density Amorphous Ice, the Frost on Interstellar Grains

    NASA Technical Reports Server (NTRS)

    Jenniskens, P.; Blake, D. F.; Wilson, M. A.; Pohorille, A.

    1995-01-01

    Most water ice in the universe is in a form which does not occur naturally on Earth and of which only minimal amounts have been made in the laboratory. We have encountered this 'high-density amorphous ice' in electron diffraction experiments of low-temperature (T less than 30 K) vapor-deposited water and have subsequently modeled its structure using molecular dynamics simulations. The characteristic feature of high-density amorphous ice is the presence of 'interstitial' oxygen pair distances between 3 and 4 A. However, we find that the structure is best described as a collapsed lattice of the more familiar low-density amorphous form. These distortions are frozen in at temperatures below 38 K because, we propose, it requires the breaking of one hydrogen bond, on average, per molecule to relieve the strain and to restructure the lattice to that of low-density amorphous ice. Several features of astrophysical ice analogs studied in laboratory experiments are readily explained by the structural transition from high-density amorphous ice into low-density amorphous ice. Changes in the shape of the 3.07 gm water band, trapping efficiency of CO, CO loss, changes in the CO band structure, and the recombination of radicals induced by low-temperature UV photolysis all covary with structural changes that occur in the ice during this amorphous to amorphous transition. While the 3.07 micrometers ice band in various astronomical environments can be modeled with spectra of simple mixtures of amorphous and crystalline forms, the contribution of the high-density amorphous form nearly always dominates.

  6. Fluid hydrogen at high density - The plasma phase transition

    NASA Technical Reports Server (NTRS)

    Saumon, D.; Chabrier, G.

    1989-01-01

    A new model equation of state is applied, based on realistic interparticle potentials and a self-consistent treatment of the internal levels, to fluid hydrogen at high density. This model shows a strong connection between molecular dissociation and pressure ionization. The possibility of a first-order plasma phase transition is considered, and for which both the evolution in temperature and the critical point is given.

  7. High density lipoproteins-based therapies for cardiovascular disease

    PubMed Central

    Gao, Xuan; Yuan, Shujun

    2010-01-01

    Atherosclerosis is the leading cause of death in developed countries. High density lipoproteins (HDL) cholesterol level correlates inversely with the risk of cardiovascular diseases. Thus, HDL has obtained lots of interest for drug development. In this review, we summarized the mechanisms for the antiatherogenic function of HDL, current HDL-based drugs in clinical use and the future direction for HDL-based therapy development. PMID:21187875

  8. Digital high density (80 Mb/s) tape

    NASA Technical Reports Server (NTRS)

    Donner, M. D.

    1977-01-01

    Work with a state-of-the-art high density PCM tape recorder reproducer system is described. The tape recorder is designed for 80 Mb/s operation at an overall bit error rate of .00001and for 40 Mb/s operation at .000001. The article describes the process of measuring the error rate. Also detailed is a data rate buffer designed for use in recent radar experiments and generalizable to most potential uses of the recorder system.

  9. The 3D Stacking Bipolar RRAM for High Density

    DTIC Science & Technology

    2011-06-01

    Bipolar RRAM for High Density Yi-Chung Chen, Hai ( Helen ) Li, Member, IEEE, Wei Zhang, Member, IEEE, Robinson E. Pino Senior Member, IEEE Abstract—For...either unipolar or bipolar switching. In this Yi-Chung Chen and Hai ( Helen ) Li are with the Department of Electrical and Computer Engineering...device co-design for emerging non- volatile memory system, FPGA, embedded system and reconfigurable computing. Hai ( Helen ) Li (M08) received the B.S. and

  10. Modeling of Homogeneous Condensation in High Density Thruster Plumes

    DTIC Science & Technology

    2010-06-04

    Density Thruster Plumes 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Ryan Jansen (USC); Natalia Gimelshein & Sergey Gimelshein...N/A Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. 239.18 Modeling of Homogeneous Condensation in High Density Thruster Plumes Ryan...related to thruster plume expansion into surrounding rarefied atmosphere.1 It is well known that particulates of different kind are the main contributor to

  11. Critical Technology Assessment: Fine Grain, High Density Graphite

    DTIC Science & Technology

    2010-04-01

    Control Classification Number ( ECCN ) 1C107.a on the Commerce Control List (CCL). The parameters of 1C107.a stem from controls established by the Missile...Technology Control Regime (MTCR). In this assessment, BIS specifically examined: • The application of ECCN 1C107.a and related licensing...export licensing process for fine grain, high density graphite controlled by ECCN 1C107.a, especially to China, requires more license conditions and

  12. Near-vacuum hohlraums for driving fusion implosions with high density carbon ablatorsa)

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, L. F.; Le Pape, S.; Divol, L.; Meezan, N. B.; Mackinnon, A. J.; Ho, D. D.; Jones, O. S.; Khan, S.; Milovich, J. L.; Ross, J. S.; Amendt, P.; Casey, D.; Celliers, P. M.; Pak, A.; Peterson, J. L.; Ralph, J.; Rygg, J. R.

    2015-05-01

    Recent experiments at the National Ignition Facility [M. J. Edwards et al., Phys. Plasmas 20, 070501 (2013)] have explored driving high-density carbon ablators with near-vacuum hohlraums, which use a minimal amount of helium gas fill. These hohlraums show improved efficiency relative to conventional gas-filled hohlraums in terms of minimal backscatter, minimal generation of suprathermal electrons, and increased hohlraum-capsule coupling. Given these advantages, near-vacuum hohlraums are a promising choice for pursuing high neutron yield implosions. Long pulse symmetry control, though, remains a challenge, as the hohlraum volume fills with material. Two mitigation methodologies have been explored, dynamic beam phasing and increased case-to-capsule ratio (larger hohlraum size relative to capsule). Unexpectedly, experiments have demonstrated that the inner laser beam propagation is better than predicted by nominal simulations, and an enhanced beam propagation model is required to match measured hot spot symmetry. Ongoing work is focused on developing a physical model which captures this enhanced propagation and on utilizing the enhanced propagation to drive longer laser pulses than originally predicted in order to reach alpha-heating dominated neutron yields.

  13. Density limits investigation and high density operation in EAST tokamak

    NASA Astrophysics Data System (ADS)

    Zheng, Xingwei; Li, Jiangang; Hu, Jiansheng; Liu, Haiqing; Jie, Yinxian; Wang, Shouxin; Li, Jiahong; Duan, Yanming; Li, Miaohui; Li, Yongchun; Zhang, Ling; Ye, Yang; Yang, Qingquan; Zhang, Tao; Cheng, Yingjie; Xu, Jichan; Wang, Liang; Xu, Liqing; Zhao, Hailin; Wang, Fudi; Lin, Shiyao; Wu, Bin; Lyu, Bo; Xu, Guosheng; Gao, Xiang; Shi, Tonghui; He, Kaiyang; Lan, Heng; Chu, Nan; Cao, Bin; Sun, Zhen; Zuo, Guizhong; Ren, Jun; Zhuang, Huidong; Li, Changzheng; Yuan, Xiaolin; Yu, Yaowei; Wang, Houyin; Chen, Yue; Wu, Jinhua; EAST Team

    2016-05-01

    Increasing the density in a tokamak is limited by the so-called density limit, which is generally performed as an appearance of disruption causing loss of plasma confinement, or a degradation of high confinement mode which could further lead to a H  →  L transition. The L-mode and H-mode density limit has been investigated in EAST tokamak. Experimental results suggest that density limits could be triggered by either edge cooling or excessive central radiation. The L-mode density limit disruption is generally triggered by edge cooling, which leads to the current profile shrinkage and then destabilizes a 2/1 tearing mode, ultimately resulting in a disruption. The L-mode density limit scaling agrees well with the Greenwald limit in EAST. The observed H-mode density limit in EAST is an operational-space limit with a value of 0.8∼ 0.9{{n}\\text{GW}} . High density H-mode heated by neutral beam injection (NBI) and lower hybrid current drive (LHCD) are analyzed, respectively. The constancy of the edge density gradients in H-mode indicates a critical limit caused perhaps by e.g. ballooning induced transport. The maximum density is accessed at the H  →  L transition which is generally caused by the excessive core radiation due to high Z impurities (Fe, Cu). Operating at a high density (>2.8× {{10}19} {{\\text{m}}-3} ) is favorable for suppressing the beam shine through NBI. High density H-mode up to 5.3× {{10}19}{{\\text{m}}-3}~≤ft(∼ 0.8{{n}\\text{GW}}\\right) could be sustained by 2 MW 4.6 GHz LHCD alone, and its current drive efficiency is studied. Statistics show that good control of impurities and recycling facilitate high density operation. With careful control of these factors, high density up to 0.93{{n}\\text{GW}} stable H-mode operation was carried out heated by 1.7 MW LHCD and 1.9 MW ion cyclotron resonance heating with supersonic molecular beam injection fueling.

  14. Characterization of the high density plasma etching process of CCTO thin films for the fabrication of very high density capacitors

    NASA Astrophysics Data System (ADS)

    Altamore, C.; Tringali, C.; Sparta', N.; Di Marco, S.; Grasso, A.; Ravesi, S.

    2010-02-01

    In this work the feasibility of CCTO (Calcium Copper Titanate) patterning by etching process is demonstrated and fully characterized in a hard to etch materials etcher. CCTO sintered in powder shows a giant relative dielectric constant (105) measured at 1 MHz at room temperature. This feature is furthermore coupled with stability from 101 Hz to 106 Hz in a wide temperature range (100K - 600K). In principle, this property can allow to fabricate very high capacitance density condenser. Due to its perovskite multi-component structure, CCTO can be considered a hard to etch material. For high density capacitor fabrication, CCTO anisotropic etching is requested by using high density plasma. The behavior of etched CCTO was studied in a HRe- (High Density Reflected electron) plasma etcher using Cl2/Ar chemistry. The relationship between the etch rate and the Cl2/Ar ratio was also studied. The effects of RF MHz, KHz Power and pressure variation, the impact of HBr addiction to the Cl2/Ar chemistry on the CCTO etch rate and on its selectivity to Pt and photo resist was investigated.

  15. Single-mode tuning of the plasmon resonance in high-density pillar arrays

    NASA Astrophysics Data System (ADS)

    Arnold, Matthew D.

    2017-03-01

    The Maxwell–Garnett (MG) effective medium model has a pure resonance controlled by volume fraction f, but is usually invalid at high density. I present special 2D structures that match quasistatic MG over the entire range 0  <  f  <  1, in several regular and semi-regular arrays, expanding the applicability of MG. Optimal contours depend on both lattice and fill-factor, transforming from circular at low f to nearly polygonal at high f. A key insight is the direct relationship between optimal surface polarization and surface position. Electrodynamic calculations underline the effect of constituent permittivity on spatial dispersion and required sizes for quasistatic response in various materials.

  16. High-density carbon capsule experiments on the national ignition facility.

    PubMed

    Ross, J S; Ho, D; Milovich, J; Döppner, T; McNaney, J; MacPhee, A G; Hamza, A; Biener, J; Robey, H F; Dewald, E L; Tommasini, R; Divol, L; Le Pape, S; Berzak Hopkins, L; Celliers, P M; Landen, O; Meezan, N B; Mackinnon, A J

    2015-02-01

    Indirect-drive implosions with a high-density carbon (HDC) capsule were conducted on the National Ignition Facility (NIF) to test HDC properties as an ablator material for inertial confinement fusion. A series of five experiments were completed with 76-μm-thick HDC capsules using a four-shock laser pulse optimized for HDC. The pulse delivered a total energy of 1.3 MJ with a peak power of 360 TW. The experiment demonstrated good laser to target coupling (∼90%) and excellent nuclear performance. A deuterium and tritium gas-filled HDC capsule implosion produced a neutron yield of 1.6×10^{15}±3×10(13), a yield over simulated in one dimension of 70%.

  17. Single-mode tuning of the plasmon resonance in high-density pillar arrays.

    PubMed

    Arnold, Matthew D

    2017-03-22

    The Maxwell-Garnett (MG) effective medium model has a pure resonance controlled by volume fraction f, but is usually invalid at high density. I present special 2D structures that match quasistatic MG over the entire range 0  <  f  <  1, in several regular and semi-regular arrays, expanding the applicability of MG. Optimal contours depend on both lattice and fill-factor, transforming from circular at low f to nearly polygonal at high f. A key insight is the direct relationship between optimal surface polarization and surface position. Electrodynamic calculations underline the effect of constituent permittivity on spatial dispersion and required sizes for quasistatic response in various materials.

  18. High-density carbon capsule experiments on the national ignition facility

    NASA Astrophysics Data System (ADS)

    Ross, J. S.; Ho, D.; Milovich, J.; Döppner, T.; McNaney, J.; MacPhee, A. G.; Hamza, A.; Biener, J.; Robey, H. F.; Dewald, E. L.; Tommasini, R.; Divol, L.; Le Pape, S.; Hopkins, L. Berzak; Celliers, P. M.; Landen, O.; Meezan, N. B.; Mackinnon, A. J.

    2015-02-01

    Indirect-drive implosions with a high-density carbon (HDC) capsule were conducted on the National Ignition Facility (NIF) to test HDC properties as an ablator material for inertial confinement fusion. A series of five experiments were completed with 76 -μ m -thick HDC capsules using a four-shock laser pulse optimized for HDC. The pulse delivered a total energy of 1.3 MJ with a peak power of 360 TW. The experiment demonstrated good laser to target coupling (˜90 % ) and excellent nuclear performance. A deuterium and tritium gas-filled HDC capsule implosion produced a neutron yield of 1.6 ×1015±3 ×1013 , a yield over simulated in one dimension of 70 % .

  19. A compact fast ionization gauge for in situ measurement of high-density neutral flow dynamics

    NASA Astrophysics Data System (ADS)

    Weber, T. E.; Intrator, T. P.

    2014-04-01

    A compact ionization gauge has been developed to carry out in situ measurements of high density (1020-1022 m-3) neutral gas flow dynamics with high temporal and spatial resolution. Key design aspects are discussed including gauge sensitivity and time response scaling with decreased probe dimensions, high-pressure operation, improved driver circuit bandwidth, and techniques for constructing a miniaturized probe head. Gas adsorption was discovered to significantly alter emission current and gauge sensitivity over timescales of several seconds. This effect must be taken into consideration when making time-resolved, high-density measurements. Over short timescales gauge response was predicted by scaling the sensitivity of a nominal Bayard-Alpert gauge to account for variations in probe dimensions and species-dependent ionization cross-section. Time-resolved neutral density profiles have been acquired in the Magnetized Shock Experiment at Los Alamos National Laboratory, providing data on the initial conditions of the ionization, plasmoid formation, and translation processes. It is shown that the desired density profiles can be achieved using a dynamic gas fill and that density can be scaled independently of the spatial profile.

  20. A compact fast ionization gauge for in situ measurement of high-density neutral flow dynamics.

    PubMed

    Weber, T E; Intrator, T P

    2014-04-01

    A compact ionization gauge has been developed to carry out in situ measurements of high density (10(20)-10(22) m(-3)) neutral gas flow dynamics with high temporal and spatial resolution. Key design aspects are discussed including gauge sensitivity and time response scaling with decreased probe dimensions, high-pressure operation, improved driver circuit bandwidth, and techniques for constructing a miniaturized probe head. Gas adsorption was discovered to significantly alter emission current and gauge sensitivity over timescales of several seconds. This effect must be taken into consideration when making time-resolved, high-density measurements. Over short timescales gauge response was predicted by scaling the sensitivity of a nominal Bayard-Alpert gauge to account for variations in probe dimensions and species-dependent ionization cross-section. Time-resolved neutral density profiles have been acquired in the Magnetized Shock Experiment at Los Alamos National Laboratory, providing data on the initial conditions of the ionization, plasmoid formation, and translation processes. It is shown that the desired density profiles can be achieved using a dynamic gas fill and that density can be scaled independently of the spatial profile.

  1. Degradation of electron-irradiated polyethylene studied by positron annihilation lifetime spectroscopy

    NASA Astrophysics Data System (ADS)

    Onodera, K.; Oka, T.; Kino, Y.; Sekine, T.

    2017-01-01

    Degradation of electron beam irradiated high-density polyethylene was studied by positron annihilation lifetime spectroscopy (PALS), micro-FT-IR, and gel fraction measurements. The obtained results indicated that ortho-positronium intensity is influenced not only by the irradiation but also the post oxidation, which illustrates that PALS may be a promising tool to monitor/evaluate the degradation of polyethylene induced by irradiation and long-term storage.

  2. Grafting functional antioxidants on highly crosslinked polyethylene

    NASA Astrophysics Data System (ADS)

    Al-Malaika, S.; Riasat, S.; Lewucha, C.

    2016-05-01

    The problem of interference of antioxidants, such as hindered phenols, with peroxide-initiated crosslinking of polyethylene was addressed through the use of functional (reactive) graftable antioxidants (g-AO). Reactive derivatives of hindered phenol and hindered amine antioxidants were synthesised, characterised and used to investigate their grafting reactions in high density polyethylene; both non-crosslinked (PE) and highly peroxide-crosslinked (PEXa). Assessment of the extent of in-situ grafting of the antioxidants, their retention after exhaustive solvent extraction in PE and PEXa, and the stabilising performance of the grafted antioxidants (g-AO) in the polymer were examined and benchmarked against conventionally stabilised crosslinked & non-crosslinked polyethylene. It was shown that the functional antioxidants graft to a high extent in PEXa, and that the level of interference of the g-AOs with the polymer crosslinking process was minimal compared to that of conventional antioxidants which bear the same antioxidant function. The much higher level of retention of the g-AOs in PEXa after exhaustive solvent extraction, compared to that of the corresponding conventional antioxidants, accounts for their superior long-term thermal stabilising performance under severe extractive conditions.

  3. High density monolithic packaging technology for digital/microwave avionics

    NASA Astrophysics Data System (ADS)

    Fertig, Timothy; Walter, Theresa; Gaver, Eric; Leahy, Kevin

    1994-10-01

    There has been a need for generic technologies and common approaches in design, development, and manufacturing of military and commercial products. This need is more pronounced and pressing today than ever before. With the objective to dramatically enhance avionics reliability, maintainability and availability (RM&A), an integrated, generic technology for packaging, cooling, and interconnection of high density and high performance circuits was developed. It is named High Density Monolithic Packaging (HDMP). Under the sponsorship of Wright Laboratory, a two-part complementary program (1990-1994), named Advanced Radio-Frequency Packaging/ARFP was contracted to Westinghouse. Under the ARFP program, the HDMP technology is being applied and its promising capability is being assessed for its ability to reduce the low power RF avionics life-cycle cost. Being better than half way through the program, the results and projections have been extremely promising. The technology assessment is approximately 50 percent complete and initial results have been extremely successful. Although the focus of the development effort has been on RF subsystems, the basic elements of HDMP technology have applications beyond RF/microwave subsystems. As digital processing speeds increase, RF/microwave design techniques must be applied to maintain high speed digital signal integrity. The basic elements of the HDMP technology are: low temperature co-fired ceramic (LTCC), solderless interconnects, multichip modules (MCM's), and composite heatsink materials. The key technology element, in this avionics availability enabling technology, is LTCC. LTCC material technology is a monolithic multilayered ceramic and conductor/metallization structure used as a substrate to support dense co-habitation of high density electronic circuits, their interconnections, and the electromechanical integrity of the integrated constituents.

  4. [Biodegradation of polyethylene].

    PubMed

    Yang, Jun; Song, Yi-ling; Qin, Xiao-yan

    2007-05-01

    Plastic material is one of the most serious solid wastes pollution. More than 40 million tons of plastics produced each year are discarded into environment. Plastics accumulated in the environment is highly resistant to biodegradation and not be able to take part in substance recycle. To increase the biodegradation efficiency of plastics by different means is the main research direction. This article reviewed the recent research works of polyethylene biodegradation that included the modification and pretreatment of polyethylene, biodegradation pathway, the relevant microbes and enzymes and the changes of physical, chemical and biological properties after biodegradation. The study directions of exploiting the kinds of life-forms of biodegradation polyethylene except the microorganisms, isolating and cloning the key enzymes and gene that could produce active groups, and enhancing the study on polyethylene biodegradation without additive were proposed.

  5. Polyethylene Glycol 3350

    MedlinePlus

    ... the stool. This increases the number of bowel movements and softens the stool so it is easier ... for polyethylene glycol 3350 to produce a bowel movement.To use the powder, follow these steps: If ...

  6. Extended length microchannels for high density high throughput electrophoresis systems

    DOEpatents

    Davidson, James C.; Balch, Joseph W.

    2000-01-01

    High throughput electrophoresis systems which provide extended well-to-read distances on smaller substrates, thus compacting the overall systems. The electrophoresis systems utilize a high density array of microchannels for electrophoresis analysis with extended read lengths. The microchannel geometry can be used individually or in conjunction to increase the effective length of a separation channel while minimally impacting the packing density of channels. One embodiment uses sinusoidal microchannels, while another embodiment uses plural microchannels interconnected by a via. The extended channel systems can be applied to virtually any type of channel confined chromatography.

  7. Biomimetic high density lipoprotein nanoparticles for nucleic acid delivery.

    PubMed

    McMahon, Kaylin M; Mutharasan, R Kannan; Tripathy, Sushant; Veliceasa, Dorina; Bobeica, Mariana; Shumaker, Dale K; Luthi, Andrea J; Helfand, Brian T; Ardehali, Hossein; Mirkin, Chad A; Volpert, Olga; Thaxton, C Shad

    2011-03-09

    We report a gold nanoparticle-templated high density lipoprotein (HDL AuNP) platform for gene therapy that combines lipid-based nucleic acid transfection strategies with HDL biomimicry. For proof-of-concept, HDL AuNPs are shown to adsorb antisense cholesterylated DNA. The conjugates are internalized by human cells, can be tracked within cells using transmission electron microscopy, and regulate target gene expression. Overall, the ability to directly image the AuNP core within cells, the chemical tailorability of the HDL AuNP platform, and the potential for cell-specific targeting afforded by HDL biomimicry make this platform appealing for nucleic acid delivery.

  8. Biomimetic High Density Lipoprotein Nanoparticles For Nucleic Acid Delivery

    PubMed Central

    McMahon, Kaylin M.; Mutharasan, R. Kannan; Tripathy, Sushant; Veliceasa, Dorina; Bobeica, Mariana; Shumaker, Dale K.; Luthi, Andrea J.; Helfand, Brian T.; Ardehali, Hossein; Mirkin, Chad A.; Volpert, Olga; Thaxton, C. Shad

    2014-01-01

    We report a gold nanoparticle-templated high density lipoprotein (HDL AuNP) platform for gene therapy which combines lipid-based nucleic acid transfection strategies with HDL biomimicry. For proof-of-concept, HDL AuNPs are shown to adsorb antisense cholesterylated DNA. The conjugates are internalized by human cells, can be tracked within cells using transmission electron microscopy (TEM), and regulate target gene expression. Overall, the ability to directly image the AuNP core within cells, the chemical tailorability of the HDL AuNP platform, and the potential for cell-specific targeting afforded by HDL biomimicry make this platform appealing for nucleic acid delivery. PMID:21319839

  9. Nanocluster deposition for high density magnetic recording tape media

    SciTech Connect

    Qiu Jiaoming; Xu Yunhao; Judy, Jack H.; Wang Jianping

    2005-05-15

    A technique for the fabrication of ultra-high density magnetic recording tape media with no risk of heating polymer substrate is reported. In this approach magnetic nanoparticles were generated by combining gas-phase nanocluster deposition and on-line heating techniques and deposited onto polymer substrate. Magnetic properties of the nanoparticles were optimized during their flight in vacuum prior to deposition. This technique is materials independent and it can fabricate nanocomposite films with high coercivity and very small film thickness. The fabricated magnetic nanoparticles have a uniform size distribution [for CoPt, 8.4% (standard deviation)] and well-defined spherical shape.

  10. High density electronic circuit and process for making

    DOEpatents

    Morgan, William P.

    1999-01-01

    High density circuits with posts that protrude beyond one surface of a substrate to provide easy mounting of devices such as integrated circuits. The posts also provide stress relief to accommodate differential thermal expansion. The process allows high interconnect density with fewer alignment restrictions and less wasted circuit area than previous processes. The resulting substrates can be test platforms for die testing and for multi-chip module substrate testing. The test platform can contain active components and emulate realistic operational conditions, replacing shorts/opens net testing.

  11. High density electronic circuit and process for making

    DOEpatents

    Morgan, W.P.

    1999-06-29

    High density circuits with posts that protrude beyond one surface of a substrate to provide easy mounting of devices such as integrated circuits are disclosed. The posts also provide stress relief to accommodate differential thermal expansion. The process allows high interconnect density with fewer alignment restrictions and less wasted circuit area than previous processes. The resulting substrates can be test platforms for die testing and for multi-chip module substrate testing. The test platform can contain active components and emulate realistic operational conditions, replacing shorts/opens net testing. 8 figs.

  12. High Density Thermal Energy Storage with Supercritical Fluids

    NASA Technical Reports Server (NTRS)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  13. Antarctic marine gravity field from high-density satellite altimetry

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.

    1992-01-01

    High-density (about 2-km profile spacing) Geosat/GM altimetry profiles were obtained for Antarctic waters (6-deg S to 72 deg S) and converted to vertical gravity gradient, using Laplace's equation to directly calculate gravity gradient from vertical deflection grids and Fourier analysis to construct gravity anomalies from two vertical deflection grids. The resultant gravity grids have resolution and accuracy comparable to shipboard gravity profiles. The obtained gravity maps display many interesting and previously uncharted features, such as a propagating rift wake and a large 'leaky transform' along the Pacific-Antarctic Rise.

  14. High Density Thermal Energy Storage with Supercritical Fluids

    NASA Technical Reports Server (NTRS)

    Ganapathi, Gani B.; Wirz, Richard

    2012-01-01

    A novel approach to storing thermal energy with supercritical fluids is being investigated, which if successful, promises to transform the way thermal energy is captured and utilized. The use of supercritical fluids allows cost-affordable high-density storage with a combination of latent heat and sensible heat in the two-phase as well as the supercritical state. This technology will enhance penetration of several thermal power generation applications and high temperature water for commercial use if the overall cost of the technology can be demonstrated to be lower than the current state-of-the-art molten salt using sodium nitrate and potassium nitrate eutectic mixtures.

  15. Near-vacuum hohlraums for driving fusion implosions with high density carbon ablators

    NASA Astrophysics Data System (ADS)

    Berzak Hopkins, Laura

    2014-10-01

    Achieving ignition requires reaching fast implosion velocities, which highlights the need for a highly efficient hohlraum to drive indirect-drive inertial confinement fusion implosions. Gas-filled hohlraums are typically utilized due to the pulse length (15-20 ns) needed to drive plastic (CH) capsules. With the recent use of 3× denser high-density carbon (HDC) capsules, ignition pulses can be less than 10 ns in duration, providing the opportunity to utilize near-vacuum hohlraums (NVH) to drive ignition-relevant implosions on the National Ignition Facility (NIF) with minimal laser-plasma instabilities which complicate standard gas-filled hohlraums. Initial NVH implosions on the NIF have demonstrated coupling efficiency significantly higher than observed in gas-filled hohlraums - backscatter losses less than 2% and virtually no suprathermal electron generation. A major design challenge for the NVH is symmetry control. Without tamping gas, the hohlraum wall quickly expands filling the volume with gold plasma. However, results to-date indicate that the inner-cone beams propagate freely to the hohlraum wall for at least 6.5 ns. With minimal predicted cross-beam power transfer, this propagation enables symmetry control via dynamic beam phasing - time-dependent direct adjustment of the inner- and outer-cone laser pulses. A series of experiments with an HDC ablator and NVH culminated in a 6 ns, 1.2 MJ cryogenic DT layered implosion yielding 1.8 × 1015 neutrons--significantly higher yield than any CH implosion at comparable energy. This implosion reached an ignition-relevant velocity -350 km/s - with no observed ablator mix in the hot spot. Recent experiments have explored two-shock designs in a larger, 6.72 mm hohlraum, and upcoming experiments will incrementally extend the pulse duration toward a 9 ns long, three-shock ignition design. Prepared by LLNL under Contract DE-AC52-07NA27344.

  16. A Coupled Plasma and Sheath Model for High Density Reactors

    NASA Technical Reports Server (NTRS)

    Deepak, Bose; Govindan, T. R.; Meyyappan, M.; Arnold, Jim (Technical Monitor)

    2001-01-01

    We present a coupled plasma and collisionless; sheath model for the simulation of high density plasma processing reactors. Due to inefficiencies in numerical schemes and the resulting computational burden, a coupled multidimensional plasma and sheath simulation has not been possible model for gas mixtures and high density reactors of practical interest. In this work we demonstrate that with a fully implicit algorithm and a refined computational mesh, a self-consistent plasma and sheath simulation is feasible. We discuss the details of the model equations, the importance of ion inertia, and the resulting sheath profiles for argon and chlorine plasmas. We find that at low operating pressures (10-30 mTorr), the charge separation occurs only within a 0.5 mm layer near the surface in a 300 mm inductively coupled plasma etch reactor. A unified model eliminates the use of off-line or loosely coupled sheath models with simplifying assumptions which generally lead to uncertainties in ion flux and sheath electrical properties.

  17. Effects of High-Density Impacts on Shielding Capability

    NASA Technical Reports Server (NTRS)

    Christiansen, Eric L.; Lear, Dana M.

    2014-01-01

    Spacecraft are shielded from micrometeoroids and orbital debris (MMOD) impacts to meet requirements for crew safety and/or mission success. In the past, orbital debris particles have been considered to be composed entirely of aluminum (medium-density material) for the purposes of MMOD shielding design and verification. Meteoroids have been considered to be low-density porous materials, with an average density of 1 g/cu cm. Recently, NASA released a new orbital debris environment model, referred to as ORDEM 3.0, that indicates orbital debris contains a substantial fraction of high-density material for which steel is used in MMOD risk assessments [Ref.1]. Similarly, an update to the meteoroid environment model is also under consideration to include a high-density component of that environment. This paper provides results of hypervelocity impact tests and hydrocode simulations on typical spacecraft MMOD shields using steel projectiles. It was found that previous ballistic limit equations (BLEs) that define the protection capability of the MMOD shields did not predict the results from the steel impact tests and hydrocode simulations (typically, the predictions from these equations were too optimistic). The ballistic limit equations required updates to more accurately represent shield protection capability from the range of densities in the orbital debris environment. Ballistic limit equations were derived from the results of the work and are provided in the paper.

  18. Generation of high-density biskyrmions by electric current

    DOE PAGES

    Peng, Licong; Zhang, Ying; He, Min; ...

    2017-06-16

    Much interest has been focused on the manipulation of magnetic skyrmions, including the generation, annihilation, and motion behaviors, for potential applications in spintronics. We experimentally demonstrate that a high-density Bloch-type biskyrmion lattice in MnNiGa can be generated by applying electric current. It is revealed that the density of biskyrmions can be remarkably increased by increasing the electric current, in contrast to the scattered biskyrmions induced by a magnetic field alone. Furthermore, the transition from the ferromagnetic state to the stripe domain structure can be terminated by the electric current, leading to the biskyrmions dominated residual domain pattern. These biskyrmions inmore » such residual domain structure are extremely stable at zero magnetic and electric fields and can further evolve into the high-density biskyrmion lattice over a temperature range from 100 to 330 K. Finally, our experimental findings open up a new pathway for the generation of skyrmion lattice by electric current manipulation.« less

  19. An evaluation of serum high density lipoproteins-phospholipids.

    PubMed

    Ide, H; Tsuji, M; Shimada, M; Kondo, T; Fujiya, S; Asanuma, Y; Agishi, Y

    1988-07-01

    Phospholipids in high density lipoproteins (HDL) is being used as a negative risk indicator of atherosclerosis. Phospholipids in HDL may not demonstrate the actual level of HDL-phospholipids when determined by the precipitation or ultracentrifugal methods, because HDL fractions contain very high density lipoproteins (VHDL) and albumin. In the present study, the true level of phospholipids in HDL was estimated using high performance liquid chromatography (HPLC), and it was compared with the level of phospholipids in HDL determined by the precipitation method. Sera from 18 healthy subjects were used as materials. In the HPLC method, the HDL fraction was extracted making sure that it contained no free albumin, which is albumin not bound to phospholipids. The HDL fraction was separated into subfractions. It was found that phospholipids in the VHDL fraction make a 20.2 +/- 7.3% (mean +/- S.D.) part of the total HDL-phospholipids. A large part of the VHDL fraction was constituted of albumin-bound phospholipids. A significant correlation was observed between HDL-phospholipids determined by the precipitation method, which contain albumin, and the actual HDL fraction phospholipids determined by HPLC, which do not contain VHDL (r = 0.903, p less than 0.01). These results suggest that HDL-phospholipids values determined by the precipitation method give useful clinical data.

  20. Simulating deposition of high density tailings using smoothed particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Babaoglu, Yagmur; Simms, Paul H.

    2017-08-01

    Tailings are a slurry of silt-sized residual material derived from the milling of rock. High density (HD) tailings are tailings that have been sufficiently dewatered to a point where they exhibit a yield stress upon deposition. They form gently sloped stacks on the surface when deposited; this eliminates or minimizes the need for dams or embankments for containment. Understanding the flow behaviour of high density tailings is essential for estimating the final stack geometry and overall slope angle. This paper focuses on modelling the flow behaviour of HD tailings using smoothed particle hydrodynamics (SPH) method incorporating a `bi-viscosity' model to simulate the non-Newtonian behaviour. The model is validated by comparing the numerical results with bench scale experiments simulating single or multi-layer deposits in two-dimensions. The results indicate that the model agreed fairly well with the experimental work, excepting some repulsion of particles away from the bottom boundary closer to the toe of the deposits. Novel aspects of the work, compared to other simulation of Bingham fluids by SPH, are the simulation of multilayer deposits and the use of a stopping criteria to characterize the rest state.

  1. Multiplexed, High Density Electrophysiology with Nanofabricated Neural Probes

    PubMed Central

    Du, Jiangang; Blanche, Timothy J.; Harrison, Reid R.; Lester, Henry A.; Masmanidis, Sotiris C.

    2011-01-01

    Extracellular electrode arrays can reveal the neuronal network correlates of behavior with single-cell, single-spike, and sub-millisecond resolution. However, implantable electrodes are inherently invasive, and efforts to scale up the number and density of recording sites must compromise on device size in order to connect the electrodes. Here, we report on silicon-based neural probes employing nanofabricated, high-density electrical leads. Furthermore, we address the challenge of reading out multichannel data with an application-specific integrated circuit (ASIC) performing signal amplification, band-pass filtering, and multiplexing functions. We demonstrate high spatial resolution extracellular measurements with a fully integrated, low noise 64-channel system weighing just 330 mg. The on-chip multiplexers make possible recordings with substantially fewer external wires than the number of input channels. By combining nanofabricated probes with ASICs we have implemented a system for performing large-scale, high-density electrophysiology in small, freely behaving animals that is both minimally invasive and highly scalable. PMID:22022568

  2. System design for OFDM systems with high-density constellations

    NASA Astrophysics Data System (ADS)

    Gu, Jian

    2001-10-01

    This paper addresses issues in designing OFDM systems with high-density constellations. To achieve high data throughput, many high-speed OFDM systems such as HiperLAN2 and IEEE 802.11a use high-density constellations such as 64QAM to reach up to 54Mbits/s over a 20 MHz frequency bandwidth. Compared with low-density constellation modulations, OFDM systems using M-QAM (M>=64) are very sensitive to analog circuits/components variations causing so-called I-Q imbalances. Moreover, for the purpose of high integration level and low cost, simple front-end radio/analog architectures such as direct conversion and low-IF are desirable but such architectures are even more sensitive to circuitry and component variation. We have developed a patent-pending technology called IQ-Balancing, which removes the adverse effect of I-Q imbalance and enables OFDM systems to have high tolerance to circuitry and component variations. With IQ-Balancing technology, direct conversion and low-IF architectures become very attractive for high-speed OFDM systems. Exploring further with IQ- balancing technology leads to a simple implementation of software Defined Radio (SDR).

  3. Loop formation of microtubules during gliding at high density

    NASA Astrophysics Data System (ADS)

    Liu, Lynn; Tüzel, Erkan; Ross, Jennifer L.

    2011-09-01

    The microtubule cytoskeleton, including the associated proteins, forms a complex network essential to multiple cellular processes. Microtubule-associated motor proteins, such as kinesin-1, travel on microtubules to transport membrane bound vesicles across the crowded cell. Other motors, such as cytoplasmic dynein and kinesin-5, are used to organize the cytoskeleton during mitosis. In order to understand the self-organization processes of motors on microtubules, we performed filament-gliding assays with kinesin-1 motors bound to the cover glass with a high density of microtubules on the surface. To observe microtubule organization, 3% of the microtubules were fluorescently labeled to serve as tracers. We find that microtubules in these assays are not confined to two dimensions and can cross one other. This causes microtubules to align locally with a relatively short correlation length. At high density, this local alignment is enough to create 'intersections' of perpendicularly oriented groups of microtubules. These intersections create vortices that cause microtubules to form loops. We characterize the radius of curvature and time duration of the loops. These different behaviors give insight into how crowded conditions, such as those in the cell, might affect motor behavior and cytoskeleton organization.

  4. Long-term oxidative degradation in polyethylene irradiated with ion beams

    NASA Astrophysics Data System (ADS)

    Hama, Yoshimasa; Oka, Toshitaka; Uchiyama, Junichi; Kanbe, Hidenori; Nabeta, Kenji; Yatagai, Fumio

    2001-07-01

    The long-term oxidative degradation for high density polyethylene (HDPE) irradiated with various ion-beams was studied. Such degradation was insignificant for low density polyethylene (LDPE) even if irradiation was carried out under the same condition as for HDPE. This is attributed to a hydroperoxide group as the initiator produced by the reaction of the allyl radical with oxygen. The relationship between the mechanical properties and the local transformation induced by ion-beam irradiation was investigated. It is seen that the depth profiles of the mechanical properties along the pathway of the injected ion correspond to that of the crosslinking induced in polyethylene.

  5. Influence of a stabilized cap layer on the photodegradation of coextruded high density polyethylene/woodflour composites

    Treesearch

    Shan Jin; Nicole M. Stark; Laurent M. Matuana

    2013-01-01

    The effect of light stabilizer’s addition method into wood-plastic composites (WPCs), i.e., surface versus bulk, on their photostability was evaluated. Blends of ultraviolet absorbers (benzotriazole or hydroxyphenyltriazine) with a hindered amine light stabilizer were used as the stabilizing additives. Both unstabilized and photostabilized uncapped (control) samples,...

  6. Effect of weathering cycle and manufacturing method on performance of wood flour and high-density polyethylene composites

    Treesearch

    Nicole M. Stark

    2006-01-01

    Wood–plastic lumber is promoted as a low-maintenance high-durability product. When exposed to accelerated weathering, however, wood–plastic composites may experience a color change and loss in mechanical properties. Differences in weathering cycle and composite surface characteristics can affect the rate and amount of change caused by weathering. In this study, 50%...

  7. 77 FR 13387 - Pipeline Safety: Notice to Operators of Driscopipe® 8000 High Density Polyethylene Pipe of the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-06

    ...-like environments in the southwestern United States. However, since root causes of the degradation have... could be verified as a root cause. In 2007, the operator experienced a gas ignition incident on a one... cooperatively with the manufacturer and regulators to determine the root causes and necessary mitigative actions...

  8. Production of Acrylonitrile Butadiene Styrene/High-Density Polyethylene Composites from Waste Sources by Using Coupling Agents

    NASA Astrophysics Data System (ADS)

    Miskolczi, N.; Szakacs, H.; Sedlarik, V.; Kucharczyk, P.; Riegel, E.

    2014-07-01

    A possible way of recycling plastic wastes has been investigated. Polyalkenyl-poly-maleic-anhydride derivates were synthesized and employed in ABS and HDPE blends to eliminate their immiscibility. By this way, the recycling of ABS and HDPE could be performed with improved mechanical properties of reshaped specimens.

  9. [Treatment of enophthalmos after severe malar-maxillary complex fracture with titanium mesh and high density polyethylene (Medpor)].

    PubMed

    Zhao, Yan-feng; Lu, Ping; Zhou, Xiao-nan; Qu, Chang-feng

    2010-03-01

    To study the surgical management of enophthalmos after severe malar maxillary complex fracture. The X-ray and CT examination were performed before operation to diagnose the orbital fracture and intraorbital tissue displacement. The fractured orbital rim was repositioned intraoperatively, followed by implantation of shaped titanium mesh to rebuild the orbital floor. The Medpor was inserted above the titanium mesh to correct the enophthalmos. From Sept. 2007 to Jan. 2009, 6 cases of enophthalmos after severe malar-maxillary complex fracture were treated. The enophthalmos was corrected or improved obviously in all the patients. The enophthalmos after severe malar-maxillary complex fracture can be corrected or obviously improved. Shaped titanium mesh can be used to rebuild the orbital floor with the Medpor to reconstruct the intraorbital tissue volume.

  10. Nanoscale design of multifunctional organic layers for low-power high-density memory devices.

    PubMed

    Nougaret, Laurianne; Kassa, Hailu G; Cai, Ronggang; Patois, Tilia; Nysten, Bernard; van Breemen, Albert J J M; Gelinck, Gerwin H; de Leeuw, Dago M; Marrani, Alessio; Hu, Zhijun; Jonas, Alain M

    2014-04-22

    We demonstrate the design of a multifunctional organic layer by the rational combination of nanosized regions of two functional polymers. Instead of relying on a spontaneous and random phase separation process or on the tedious synthesis of block copolymers, the method involves the nanomolding of a first component, followed by the filling of the resulting open spaces by a second component. We apply this methodology to fabricate organic nonvolatile memory diodes of high density. These are built by first creating a regular array of ferroelectric nanodots by nanoimprint lithography, followed by the filling of the trenches separating the ferroelectric nanodots with a semiconducting polymer. The modulation of the current in the semiconductor by the polarization state of the ferroelectric material is demonstrated both at the scale of a single semiconductor channel and in a microscopic device measuring about 80,000 channels in parallel, for voltages below ca. 2 V. The fabrication process, which combines synergetically orthogonal functional properties with a fine control over their spatial distribution, is thus demonstrated to be efficient over large areas.

  11. High density propellant for single stage to orbit vehicles

    NASA Technical Reports Server (NTRS)

    Notardonato, J. J.; Masters, P. A.

    1976-01-01

    Mixed mode propulsion concepts are studied for advanced, single stage earth orbital transportation systems (SSTO) for use in the post-1990 time period. These propulsion concepts are based on the sequential and/or parallel use of high density impulse and high specific impulse propellants in a single stage to increase vehicle performance and reduce dry weight. Specifically, the mixed mode concept utilizes two propulsion systems with two different fuels (mode 1 and mode 2) with liquid oxygen as a common oxidizer. Mode 1 engines would burn a high bulk density fuel for lift-off and early ascent to minimize performance penalties associated with carrying fuel tankage to orbit. Mode 2 engines will complete orbital injection utilizing liquid hydrogen as the fuel.

  12. Microelectromechanical high-density energy storage/rapid release system

    NASA Astrophysics Data System (ADS)

    Rodgers, M. Steven; Allen, James J.; Meeks, Kent D.; Jensen, Brian D.; Miller, Samuel L.

    1999-08-01

    One highly desirable characteristic of electrostatically driven microelectromechanical systems (MEMS) is that they consume very little power. The corresponding drawback is that the force they produce may be inadequate for many applications. It has previously been demonstrated that gear reduction units or microtransmissions can substantially increase the torque generated by microengines. Operating speed, however, is also reduced by the transmission gear ratio. Some applications require both high speed and high force. If this output is only required for a limited period of time, then energy could be stored in a mechanical system and rapidly released upon demand. We have designed, fabricated, and demonstrated a high-density energy storage/rapid release system that accomplishes this task. Built using a 5-level surface micromachining technology, the assembly closely resembles a medieval crossbow. Energy releases on the order of tens of nanojoules have already been demonstrated, and significantly higher energy systems are under development.

  13. High density operation for reactor-relevant power exhaust

    NASA Astrophysics Data System (ADS)

    Wischmeier, M.

    2015-08-01

    With increasing size of a tokamak device and associated fusion power gain an increasing power flux density towards the divertor needs to be handled. A solution for handling this power flux is crucial for a safe and economic operation. Using purely geometric arguments in an ITER-like divertor this power flux can be reduced by approximately a factor 100. Based on a conservative extrapolation of current technology for an integrated engineering approach to remove power deposited on plasma facing components a further reduction of the power flux density via volumetric processes in the plasma by up to a factor of 50 is required. Our current ability to interpret existing power exhaust scenarios using numerical transport codes is analyzed and an operational scenario as a potential solution for ITER like divertors under high density and highly radiating reactor-relevant conditions is presented. Alternative concepts for risk mitigation as well as strategies for moving forward are outlined.

  14. Neural network based feed-forward high density associative memory

    NASA Technical Reports Server (NTRS)

    Daud, T.; Moopenn, A.; Lamb, J. L.; Ramesham, R.; Thakoor, A. P.

    1987-01-01

    A novel thin film approach to neural-network-based high-density associative memory is described. The information is stored locally in a memory matrix of passive, nonvolatile, binary connection elements with a potential to achieve a storage density of 10 to the 9th bits/sq cm. Microswitches based on memory switching in thin film hydrogenated amorphous silicon, and alternatively in manganese oxide, have been used as programmable read-only memory elements. Low-energy switching has been ascertained in both these materials. Fabrication and testing of memory matrix is described. High-speed associative recall approaching 10 to the 7th bits/sec and high storage capacity in such a connection matrix memory system is also described.

  15. A distributed current stimulator ASIC for high density neural stimulation.

    PubMed

    Jeong Hoan Park; Chaebin Kim; Seung-Hee Ahn; Tae Mok Gwon; Joonsoo Jeong; Sang Beom Jun; Sung June Kim

    2016-08-01

    This paper presents a novel distributed neural stimulator scheme. Instead of a single stimulator ASIC in the package, multiple ASICs are embedded at each electrode site for stimulation with a high density electrode array. This distributed architecture enables the simplification of wiring between electrodes and stimulator ASIC that otherwise could become too complex as the number of electrode increases. The individual ASIC chip is designed to have a shared data bus that independently controls multiple stimulating channels. Therefore, the number of metal lines is determined by the distributed ASICs, not by the channel number. The function of current steering is also implemented within each ASIC in order to increase the effective number of channels via pseudo channel stimulation. Therefore, the chip area can be used more efficiently. The designed chip was fabricated with area of 0.3 mm2 using 0.18 μm BCDMOS process, and the bench-top test was also conducted to validate chip performance.

  16. High-density percutaneous chronic connector for neural prosthetics

    DOEpatents

    Shah, Kedar G.; Bennett, William J.; Pannu, Satinderpall S.

    2015-09-22

    A high density percutaneous chronic connector, having first and second connector structures each having an array of magnets surrounding a mounting cavity. A first electrical feedthrough array is seated in the mounting cavity of the first connector structure and a second electrical feedthrough array is seated in the mounting cavity of the second connector structure, with a feedthrough interconnect matrix positioned between a top side of the first electrical feedthrough array and a bottom side of the second electrical feedthrough array to electrically connect the first electrical feedthrough array to the second electrical feedthrough array. The two arrays of magnets are arranged to attract in a first angular position which connects the first and second connector structures together and electrically connects the percutaneously connected device to the external electronics, and to repel in a second angular position to facilitate removal of the second connector structure from the first connector structure.

  17. High-Density Lipoprotein and Prostate Cancer: An Overview

    PubMed Central

    Kotani, Kazuhiko; Sekine, Yoshitaka; Ishikawa, Shizukiyo; Ikpot, Imoh Z.; Suzuki, Kazuhiro; Remaley, Alan T.

    2013-01-01

    Prostate cancer is a common disease in modern, developed societies and has a high incidence and mortality. High-density lipoprotein cholesterol (HDL-C) has recently received much attention as a possible risk marker of prostate cancer development and prognosis. In the present article, we summarized findings from epidemiologic studies of the association between HDL-C and prostate cancer. Low HDL-C level was found to be a risk and prognostic factor of prostate cancer in several epidemiologic studies, although the overall linkage between HDL and prostate cancer has not been definitively established. The mechanisms for this association remain uncertain; however, limited data from experimental studies imply a possible role of HDL in the pathophysiology of prostate cancer. More epidemiologic research, in combination with experimental studies, is needed in this field. PMID:23985823

  18. High-density equation of state for a lattice gas.

    PubMed

    Ushcats, M V

    2015-05-01

    For the lattice gas models of arbitrary geometry and dimensions with absolute repulsion between particles at zero distance (a hard core identical to a single lattice site) and arbitrary repulsion or attraction at other distances, the "hole-particle" symmetry of the system potential energy has been stated and an equation of state has been derived on the basis of the classical Gibbs statistics. The equation is completely analogous to the well-known virial equation of state, except that it is more accurate at high-density states, while the virial equation has the low-density limitation. Both equations contain the common set of the so-called irreducible integrals, related to the corresponding virial coefficients, and can be used together to describe the behavior of a lattice gas in a wide range of densities.

  19. A ferroelectric DRAM cell for high-density NVRAM's

    NASA Astrophysics Data System (ADS)

    Moazzami, Reza; Hu, Chenming; Shepherd, William H.

    1990-10-01

    The operation of a ferroelectric DRAM (dynamic random-access memory) cell for nonvolatile RAM (NVRAM) applications is described. Because polarization reversal only occurs during nonvolatile store/recall operations and not during read/write operations, ferroelectric fatigue is not a serious endurance problem. For a 3-V power supply, the worst-case effective silicon dioxide thickness of the unoptimized lead zirconate titanate film studied is less than 1.7 nm. The resistivity and endurance properties of ferroelectric films can be optimized by modifying the composition of the film. This cell can be the basis of a very-high-density NVRAM with practically no read/write cycle limit and at least 10 to the 10th nonvolatile store/recall cycles.

  20. Relaxation time of high-density amorphous ice.

    PubMed

    Handle, Philip H; Seidl, Markus; Loerting, Thomas

    2012-06-01

    Amorphous water plays a fundamental role in astrophysics, cryoelectron microscopy, hydration of matter, and our understanding of anomalous liquid water properties. Yet, the characteristics of the relaxation processes taking place in high-density amorphous ice (HDA) are unknown. We here reveal that the relaxation processes in HDA at 110-135 K at 0.1-0.2 GPa are of collective and global nature, resembling the alpha relaxation in glassy material. Measured relaxation times suggest liquid-like relaxation characteristics in the vicinity of the crystallization temperature at 145 K. By carefully relaxing pressurized HDA for several hours at 135 K, we produce a state that is closer to the ideal glass state than all HDA states discussed so far in literature.

  1. Can phosphatidylserine enhance atheroprotective activities of high-density lipoprotein?

    PubMed

    Darabi, Maryam; Kontush, Anatol

    2016-01-01

    Although high-density lipoprotein (HDL) is well known to be protective against atherosclerotic cardiovascular disease, therapeutic interventions to raise HDL-cholesterol levels do not translate into reduction in cardiovascular risk. Due to the compositional complexity of HDL particles, molecular determinants of their atheroprotective function still remain to be clarified. Recent structural and functional data identify phospholipid as a major bioactive component of HDL. Such a role has recently been specifically evidenced for phosphatidylserine (PS); indeed, HDL content of PS displayed positive correlations with all metrics of HDL functionality assessed. This review summarizes current knowledge about HDL-associated PS; possible mechanisms for its atheroprotective role are discussed and potential applications of PS to HDL-based therapies are highlighted.

  2. Measurements of uranium mass confined in high density plasmas

    NASA Technical Reports Server (NTRS)

    Stoeffler, R. C.

    1976-01-01

    An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

  3. Ultracold molecular Rydberg physics in a high density environment

    NASA Astrophysics Data System (ADS)

    Eiles, Matthew T.; Pérez-Ríos, Jesús; Robicheaux, F.; Greene, Chris H.

    2016-06-01

    Sufficiently high densities in Bose-Einstein condensates provide favorable conditions for the production of ultralong-range polyatomic molecules consisting of one Rydberg atom and a number of neutral ground state atoms. The chemical binding properties and electronic wave functions of these exotic molecules are investigated analytically via hybridized diatomic states. The effects of the molecular geometry on the system’s properties are studied through comparisons of the adiabatic potential curves and electronic structures for both symmetric and randomly configured molecular geometries. General properties of these molecules with increasing numbers of constituent atoms and in different geometries are presented. These polyatomic states have spectral signatures that lead to non-Lorentzian line-profiles.

  4. Selection and microstructures of high density uranium alloys

    SciTech Connect

    Meyer, M.K.; Trybus, C.L.; Hofman, G.L.; Frank, S.M.; Wiencek, T.C.

    1997-10-01

    Twelve uranium alloys have been selected for incorporation into very high density aluminum dispersion fuel plates for irradiation testing. These alloys are (nominally) U-10Mo, U-8Mo, U-6Mo, U-4Mo, U-9Nb-3Zr, U-6Nb-4Zr, U-5Nb-3Zr, U-2Mo-1Nb-1Zr, U-6Mo-1Pt, U-6Mo-0.6Ru, U-6Mo-0.6Si, and U-10Mo-0.05Sn. The rationale for selection of these fuels based on gamma phase stability, reports of good irradiation performance, and high uranium density will be discussed. The microstructures of these fuels were examined by SEM/EDS and XRD at three storage during the powder fabrication process. Microstructures of selected alloys are discussed.

  5. High-density deformable mirrors to enable coronographic planet detection

    NASA Astrophysics Data System (ADS)

    Ealey, Mark A.; Trauger, John T.

    2004-02-01

    Active wavefront correction of a space telescope provides a technology path for extremely high contrast imaging astronomy at levels well beyond the capabilities of current telescope systems. A precision deformable mirror technology intended specifically for wavefront correction in a visible/near-infrared space telescope has been developed at Xinetics and extensively tested at JPL over the past several years. Active wavefront phase correction has been demonstrated to 1-Angstrom rms over the spatial frequency range accessible to a mirror with an array of actuators on a 1-mm pitch. High density deformable mirror technology is based on a modular actuator arrays that are scalable to 1000s of actuator elements coupled to the surface of a thin mirror facesheet. Precision actuator control is done by using a low-power, vacuum compatible multiplexed driver system. Mirror surface figure, actuator influence function, and dimensional stability will be given in the context of the Eclipse point design for a coronagraphic space telescope.

  6. Methods and systems for rapid prototyping of high density circuits

    SciTech Connect

    Palmer, Jeremy A.; Davis, Donald W.; Chavez, Bart D.; Gallegos, Phillip L.; Wicker, Ryan B.; Medina, Francisco R.

    2008-09-02

    A preferred embodiment provides, for example, a system and method of integrating fluid media dispensing technology such as direct-write (DW) technologies with rapid prototyping (RP) technologies such as stereolithography (SL) to provide increased micro-fabrication and micro-stereolithography. A preferred embodiment of the present invention also provides, for example, a system and method for Rapid Prototyping High Density Circuit (RPHDC) manufacturing of solderless connectors and pilot devices with terminal geometries that are compatible with DW mechanisms and reduce contact resistance where the electrical system is encapsulated within structural members and manual electrical connections are eliminated in favor of automated DW traces. A preferred embodiment further provides, for example, a method of rapid prototyping comprising: fabricating a part layer using stereolithography and depositing thermally curable media onto the part layer using a fluid dispensing apparatus.

  7. Characterization of high density through silicon vias with spectral reflectometry.

    PubMed

    Ku, Yi-Sha; Huang, Kuo Cheng; Hsu, Weite

    2011-03-28

    Measurement and control is an important step for production-worthy through silicon vias etch. We demonstrate the use and enhancement of an existing wafer metrology tool, spectral reflectometer by implementing novel theoretical model and measurement algorithm for high density through-silicon via (HDTSV) inspection. It is capable of measuring depth and depth variations of array vias by Discrete Fourier Transform (DFT) analysis in one shot measurement. Surface roughness of via bottom can also be extracted by scattering model fitting. Our non-destructive solution can measure TSV profile diameters as small as 5 μm and aspect ratios greater than 13:1. The measurement precision is in the range of 0.02 μm. Metrology results from actual 3D interconnect processing wafers are presented.

  8. Measurements of uranium mass confined in high density plasmas

    NASA Technical Reports Server (NTRS)

    Stoeffler, R. C.

    1976-01-01

    An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

  9. Niobium flex cable for low temperature high density interconnects

    NASA Astrophysics Data System (ADS)

    van Weers, H. J.; Kunkel, G.; Lindeman, M. A.; Leeman, M.

    2013-05-01

    This work describes the fabrication and characterization of a Niobium on polyimide flex cable suitable for sub-Kelvin temperatures. The processing used can be extended to high density interconnects and allows for direct integration with printed circuit boards. Several key parameters such as RRR, Tc, current carrying capability at 4 K and thermal conductivity in the range from 0.15 to 10 K have been measured. The average Tc was found to be 8.9 K, with a minimum of 8.3 K. Several samples allowed for more than 50 mA current at 4 K while remaining in the superconducting state. The thermal conductivity for this flex design is dominated by the polyimide, in our case Pyralin PI-2611, and is in good agreement with published thermal conductivity data for a polyimide called Upilex R. Registered trademark of Ube Industries, Japan.

  10. High Density Memory Based on Quantum Device Technology

    NASA Technical Reports Server (NTRS)

    vanderWagt, Paul; Frazier, Gary; Tang, Hao

    1995-01-01

    We explore the feasibility of ultra-high density memory based on quantum devices. Starting from overall constraints on chip area, power consumption, access speed, and noise margin, we deduce boundaries on single cell parameters such as required operating voltage and standby current. Next, the possible role of quantum devices is examined. Since the most mature quantum device, the resonant tunneling diode (RTD) can easily be integrated vertically, it naturally leads to the issue of 3D integrated memory. We propose a novel method of addressing vertically integrated bistable two-terminal devices, such as resonant tunneling diodes (RTD) and Esaki diodes, that avoids individual physical contacts. The new concept has been demonstrated experimentally in memory cells of field effect transistors (FET's) and stacked RTD's.

  11. Biominetic High Density Lipoproteins for the Delivery of Therapeutic Oligonucleotides

    NASA Astrophysics Data System (ADS)

    Tripathy, Sushant

    Advances in nanotechnology have brought about novel inorganic and hybrid nanoparticles with unique physico-chemical properties that make them suitable for a broad range of applications---from nano-circuitry to drug delivery. A significant part of those advancements have led to ground-breaking discoveries that have changed the approaches to formulation of therapeutics against diseases, such as cancer. Now-a-days the focus does not lie solely on finding a candidate small-molecule therapeutic with minimal adverse effects, but researchers are looking up to nanoparticles to improve biodistribution and biocompatibility profile of clinically proven therapeutics. The plethora of conjugation chemistries offered by currently extant inorganic nanoparticles have, in recent years, led to great leaps in the field of biomimicry---a modality that promises high biocompatibility. Further, in the pursuit of highly specific therapeutic molecules, researchers have turned to silencing oligonucleotides and some have already brought together the strengths of nanoparticles and silencing oligonucleotides in search of an efficacious therapy for cancer with minimal adverse effects. This dissertation work focuses on such a biomimetic platform---a gold nanoparticle based high density lipoprotein biomimetic (HDL NP), for the delivery of therapeutic oligonucleotides. The first chapter of this body of work introduces the molecular target of the silencing oligonucleotides---VEGFR2, and its role in the progression of solid tumor cancers. The background information also covers important aspects of natural high density lipoproteins (HDL), especially their innate capacity to bind and deliver exogenous and endogenous silencing oligonucleotides to tissues that express their high affinity receptor SRB1. We subsequently describe the synthesis of the biomimetic HDL NP and its oligonucleotide conjugates, and establish their biocompatibility. Further on, experimental data demonstrate the efficacy of silencing

  12. The glass transition in high-density amorphous ice

    PubMed Central

    Loerting, Thomas; Fuentes-Landete, Violeta; Handle, Philip H.; Seidl, Markus; Amann-Winkel, Katrin; Gainaru, Catalin; Böhmer, Roland

    2015-01-01

    There has been a long controversy regarding the glass transition in low-density amorphous ice (LDA). The central question is whether or not it transforms to an ultraviscous liquid state above 136 K at ambient pressure prior to crystallization. Currently, the most widespread interpretation of the experimental findings is in terms of a transformation to a superstrong liquid above 136 K. In the last decade some work has also been devoted to the study of the glass transition in high-density amorphous ice (HDA) which is in the focus of the present review. At ambient pressure HDA is metastable against both ice I and LDA, whereas at > 0.2 GPa HDA is no longer metastable against LDA, but merely against high-pressure forms of crystalline ice. The first experimental observation interpreted as the glass transition of HDA was made using in situ methods by Mishima, who reported a glass transition temperature Tg of 160 K at 0.40 GPa. Soon thereafter Andersson and Inaba reported a much lower glass transition temperature of 122 K at 1.0 GPa. Based on the pressure dependence of HDA's Tg measured in Innsbruck, we suggest that they were in fact probing the distinct glass transition of very high-density amorphous ice (VHDA). Very recently the glass transition in HDA was also observed at ambient pressure at 116 K. That is, LDA and HDA show two distinct glass transitions, clearly separated by about 20 K at ambient pressure. In summary, this suggests that three glass transition lines can be defined in the p–T plane for LDA, HDA, and VHDA. PMID:25641986

  13. Self-Healing of Polyethylene Oxide

    NASA Astrophysics Data System (ADS)

    Chipara, Dorina Magdalena; Flores, Maritza; Puente, Nancy; Lozano, Karen

    2011-03-01

    Autonomic self-healing is expected to enhance the lifetime of polymeric materials, resins, and composites subjected to long term mechanical stresses. The self-healing process is initiated by the rupture of some polyurea-formaldehyde microcapsules filled with monomer. The self-healing polymer is actually a compound containing microcapsules filled with monomer and catalyst particles. The monomer released from these broken microcapsules is diffusing within the polymer, reacting with the catalyst and starting a polymerization reaction. This new polymer, growing within the propagating crack, stops the mechanical failure. While the process is pretty slow (timescale of the order of 10 to 100 s), there are many important technological applications that would benefit from the availability of self-healing polymers. We report about the addition of self-healing capabilities to polyethylene oxide by using polyurea formaldehyde microcapsules filled with dicyclopentadiene and first generation Grubbs catalysts. Details regarding the physical and chemical steps used to add self-healing capabilities to polyethylene oxide will be presented. Self-healing efficiency was assessed by fatigues tests.

  14. Biological resistance of polyethylene composites made with chemically modified fiber or flour

    Treesearch

    Rebecca E. Ibach; Craig M. Clemons

    2002-01-01

    The role of moisture in the biological decay of wood-plastic composites was investigated. Southern pine wood fiber and ponderosa pine wood flour were chemically modified using either acetic anhydride (AA), butylene oxide (BO), or propylene oxide (PO). A 50:50 mixture of high density polyethylene and either chemically modified fiber or flour, or untreated fiber or flour...

  15. Morphology and properties of wood-fiber reinforced blends of recycled polystyrene and polyethylene

    Treesearch

    John Simonsen; Timothy G. Rials

    1996-01-01

    Material properties of composites produced from recycled plastics and recycled wood fiber were compared. A blend of high-density polyethylene and polystyrene was used as a simulated mixed plastic. Stiffness was generally improved by the addition of fiber, as expected, but brittleness also increased. Pre-treatment of the wood filler with phenol-formaldehyde resins did...

  16. Method for casting polyethylene pipe

    NASA Technical Reports Server (NTRS)

    Elam, R. M., Jr.

    1973-01-01

    Short lengths of 7-cm ID polyethylene pipe are cast in a mold which has a core made of room-temperature-vulcanizable (RTV) silicone. Core expands during casting and shrinks on cooling to allow for contraction of the polyethylene.

  17. High Density And High Temperature Plasmas In Large Helical Device

    NASA Astrophysics Data System (ADS)

    Komori, A.

    2010-07-01

    For the realization of the fusion reactor, it is necessary to confine high density and high temperature plasma for a time, which is well known as the Lawson criterion. To improve the plasma or confinement performance, vigorous experiments have been performed in the Large Helical Device (LHD) in National Institute for Fusion Science, which is the largest superconducting heliotron device with R = 3.9 m r = 0.6 m, Bt = 3 T. Recently a promising confinement regime called Super Dense Core (SDC) mode was discovered. An extremely high density core region with more than ~ 1 × 10^20 m-3 is obtained with the formation of an Internal Diffusion Barrier (IDB). The density gradient at the IDB (? = 0.6) is very high and the particle confinement in the core region is ~ 0.2 s. It is expected, for the future reactor, that the IDB-SDC mode has a possibility to achieve the self-ignition condition with lower temperature than expected before. The IDB-SDC mode is also favorable from the engineering point of view since one can moderate demands for heating devices and plasma facing components. In order to achieve the IDB-SDC mode, the central fuelling with the pellet injection and the low recycling condition are essential. A repetitive pellet injector was newly developed to continuously feed the particle source to the central region. For the recycling control, the effective divertor system should be employed to control the edge plasma. Conventional approaches to increase the temperature have also been tried in LHD. For the ion heating, the perpendicular neutral beam injection effectively increased the ion temperature more than 10 keV with the formation of the internal transport barrier (ITB). In the core region, the heat conductivity is improved to the neoclassical level, while no clear ITB for electron was seen. Another interesting phenomenon called "impurity hole" was observed inside the ITB. During the high ion temperature discharge, the im- purity density in the core region becomes

  18. Wake High-Density Electroencephalographic Spatiospectral Signatures of Insomnia

    PubMed Central

    Colombo, Michele A.; Ramautar, Jennifer R.; Wei, Yishul; Gomez-Herrero, Germán; Stoffers, Diederick; Wassing, Rick; Benjamins, Jeroen S.; Tagliazucchi, Enzo; van der Werf, Ysbrand D.; Cajochen, Christian; Van Someren, Eus J.W.

    2016-01-01

    Study Objectives: Although daytime complaints are a defining characteristic of insomnia, most EEG studies evaluated sleep only. We used high-density electroencephalography to investigate wake resting state oscillations characteristic of insomnia disorder (ID) at a fine-grained spatiospectral resolution. Methods: A case-control assessment during eyes open (EO) and eyes closed (EC) was performed in a laboratory for human physiology. Participants (n = 94, 74 female, 21–70 y) were recruited through www.sleepregistry.nl: 51 with ID, according to DSM-5 and 43 matched controls. Exclusion criteria were any somatic, neurological or psychiatric condition. Group differences in the spectral power topographies across multiple frequencies (1.5 to 40 Hz) were evaluated using permutation-based inference with Threshold-Free Cluster-Enhancement, to correct for multiple comparisons. Results: As compared to controls, participants with ID showed less power in a narrow upper alpha band (11–12.7 Hz, peak: 11.7 Hz) over bilateral frontal and left temporal regions during EO, and more power in a broad beta frequency range (16.3–40 Hz, peak: 19 Hz) globally during EC. Source estimates suggested global rather than cortically localized group differences. Conclusions: The widespread high power in a broad beta band reported previously during sleep in insomnia is present as well during eyes closed wakefulness, suggestive of a round-the-clock hyperarousal. Low power in the upper alpha band during eyes open is consistent with low cortical inhibition and attentional filtering. The fine-grained HD-EEG findings suggest that, while more feasible than PSG, wake EEG of short duration with a few well-chosen electrodes and frequency bands, can provide valuable features of insomnia. Citation: Colombo MA, Ramautar JR, Wei Y, Gomez-Herrero G, Stoffers D, Wassing R, Benjamins JS, Tagliazucchi E, van der Werf YD, Cajochen C, Van Someren EJW. Wake high-density electroencephalographic spatiospectral

  19. Thermal analysis of polyethylene + X% carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Lozovyi, Fedir; Ivanenko, Kateryna; Nedilko, Sergii; Revo, Sergiy; Hamamda, Smail

    2016-02-01

    The aim of this research is to study the influence of the multi-walled carbon nanotubes (MWCNTs) on the thermomechanical and structural properties of high-density polyethylene. Several, complementary experimental techniques were used, namely, dilatometry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman spectroscopy, and infrared (IR) spectroscopy. Dilatometry data showed that nanocomposites exhibit anisotropic behavior, and intensity of the anisotropy depends on the MWCNT concentration. The shapes of the dilatometric curves of the nanocomposites under study differ significantly for the radial and longitudinal directions of the samples. DSC results show that MWCNTs weekly influence calorimetry data, while Raman spectra show that the I D/ I G ratio decreases when MWCNT concentration increases. The IR spectra demonstrate improvement of the crystallinity of the samples as the content in MWCNTs rises.

  20. Impact behavior of hydroxyapatite reinforced polyethylene composites.

    PubMed

    Zhang, Y; Tanner, K E

    2003-01-01

    Hydroxyapatite particulate reinforced high density polyethylene composite (HA-HDPE) has been developed as a bone replacement material. The impact behavior of the composites at 37 degrees C has been investigated using an instrumented falling weight impact testing machine. The fracture surfaces were examined using SEM and the fracture mechanisms are discussed. It was found that the fracture toughness of HA-HDPE composites increased with HDPE molecular weight, but decreased with increasing HA volume fraction. Examination of fracture surfaces revealed weak filler/matrix interfaces which can debond easily to enable crack initiation and propagation. Increasing HA volume fraction increases the interface area, and more cracks can form and develop, thus decreasing the impact resistance of the composites. Another important factor for the impact behavior of the composites is the matrix. At higher molecular weight, HDPE is able to sustain more plastic deformation and dissipates more impact energy, hence improving the impact property.

  1. Stress crack testing of polyethylene geomembranes

    NASA Astrophysics Data System (ADS)

    Halse, Y. H.; Koerner, R. M.; Lord, A. E., Jr.

    The sensitivity of high density polyethylene (HDPE) geomembranes to stress cracking is evaluated under accelerated conditions at a constant stress. The test specimens are in accordance with ASTM D-1822, and are of the dumbbell shape with a constant length in the central section. The accelerated testing conditions consist of a 10 percent Igepal wetting solution in tap water, at a constant temperature of 50 C. The applied stresses are from 30 to 50 percent of the yield stress. It was found that most commercially available HDPE sheet material performs quite well in this type of test. Only one specimen in 80 showed any evidence of cracking and this may have been caused by other reasons. Testing of field fabricated seams, however, resulted in relatively large numbers of cracked specimens. Many of these test specimens showed signs of overgrinding and/or overheating. The results indicate that great care and excellent workmanship are required in the field fabrication of HDPE seams.

  2. Method for shaping polyethylene tubing

    NASA Technical Reports Server (NTRS)

    Kramer, R. C.

    1981-01-01

    Method forms polyethylene plastic tubing into configurations previously only possible with metal tubing. By using polyethylene in place of copper or stain less steel tubing inlow pressure systems, fabrication costs are significantly reduced. Polyethylene tubing can be used whenever low pressure tubing is needed in oil operations, aircraft and space applications, powerplants, and testing laboratories.

  3. Irradiation testing of high density uranium alloy dispersion fuels

    SciTech Connect

    Hayes, S.L.; Trybus, C.L.; Meyer, M.K.

    1997-10-01

    Two irradiation test vehicles have been designed, fabricated, and inserted into the Advanced Test Reactor in Idaho. Irradiation of these experiments began in August 1997. These irradiation tests were designed to obtain irradiation performance information on a variety of potential new, high-density dispersion fuels. Each of the two irradiation vehicles contains 32 microplates. Each microplate is aluminum clad, having an aluminum matrix phase and containing one of the following compositions as the fuel phase: U-10Mo, U-8Mo, U-6Mo, U-4Mo, U-9Nb-3Zr, U-6Nb-4Zr, U-5Nb-3Zr, U-6Mo-1Pt, U-6Mo-0.6Ru, U-10Mo-0.05Sn, U{sub 2}Mo, or U{sub 3}Si{sub 2}. These experiments will be discharged at peak fuel burnups of 40% and 80%. Of particular interest is the fission gas retention/swelling characteristics of these new fuel alloys. This paper presents the design of the irradiation vehicles and the irradiation conditions.

  4. High-Density Lipoprotein, Lecithin: Cholesterol Acyltransferase, and Atherosclerosis

    PubMed Central

    Ossoli, Alice; Pavanello, Chiara

    2016-01-01

    Epidemiological data clearly show the existence of a strong inverse correlation between plasma high-density lipoprotein cholesterol (HDL-C) concentrations and the incidence of coronary heart disease. This relation is explained by a number of atheroprotective properties of HDL, first of all the ability to promote macrophage cholesterol transport. HDL are highly heterogeneous and are continuously remodeled in plasma thanks to the action of a number of proteins and enzymes. Among them, lecithin:cholesterol acyltransferase (LCAT) plays a crucial role, being the only enzyme able to esterify cholesterol within lipoproteins. LCAT is synthetized by the liver and it has been thought to play a major role in reverse cholesterol transport and in atheroprotection. However, data from animal studies, as well as human studies, have shown contradictory results. Increased LCAT concentrations are associated with increased HDL-C levels but not necessarily with atheroprotection. On the other side, decreased LCAT concentration and activity are associated with decreased HDL-C levels but not with increased atherosclerosis. These contradictory results confirm that HDL-C levels per se do not represent the functionality of the HDL system. PMID:27302716

  5. Downscaled Soil Moisture from SMAP Evaluated Using High Density Observations

    NASA Astrophysics Data System (ADS)

    Wakefield, R. A.; Basara, J. B.; Fang, B.; Lakshmi, V.; Starks, P. J.; Cosh, M. H.; Steiner, J. L.; Xiao, X.; Illston, B.

    2016-12-01

    Recently, a soil moisture downscaling algorithm based on a regression relationship between daily temperature changes and daily average soil moisture was developed to produce an enhanced spatial resolution on soil moisture product for the Advanced Microwave Scanning Radiometer-EOS (AMSR-E) satellite platform. This study applies the downscaling algorithm to coarse resolution observations collected by the Soil Moisture Active Passive (SMAP) satellite platform during the bulk of the growing season period spanning May through September for 2015 and 2016 over the Southern Great Plains (SGP) of the United States. The resultant downscaled soil moisture values at a spatial resolution of 1 km were compared with high density in situ observations at (1) the Marena Oklahoma In Situ Soil Moisture Testbed (MOISST) near Marena, OK and (2) three Integrated Grassland/Cropland Observing System (IGOS/ICOS) sites deployed at the United States Department of Agriculture (USDA) Grazinglands Research Laboratory (GRL) near El Reno, Oklahoma. Each in situ location (i.e., MOISST, two IGOS sites, and one ICOS site) includes a Cosmic Ray Soil Moisture Observing System (COSMOS) and point scale observations from various in situ sensors (e.g., Stevens Water Hydra Probe, Campbell Scientific 616 and 229, Decagon EC-TM, Delta-T Theta Probe, etc.) deployed in arrays within the COSMOS footprint. Each primary evaluation location (MOISST and GRL) also includes an Oklahoma Mesonet site.

  6. Atomistic Simulation of High-Density Uranium Fuels

    DOE PAGES

    Garcés, Jorge Eduardo; Bozzolo, Guillermo

    2011-01-01

    We apply an atomistic modeling approach to deal with interfacial phenomena in high-density uranium fuels. The effects of Si, as additive to Al or as U-Mo-particles coating, on the behavior of the Al/U-Mo interface is modeled by using the Bozzolo-Ferrante-Smith (BFS) method for alloys. The basic experimental features characterizing the real system are identified, via simulations and atom-by-atom analysis. These include (1) the trend indicating formation of interfacial compounds, (2) much reduced diffusion of Al into U-Mo solid solution due to the high Si concentration, (3) Si depletion in the Al matrix, (4) an unexpected interaction between Mo and Simore » which inhibits Si diffusion to deeper layers in the U-Mo solid solution, and (5) the minimum amount of Si needed to perform as an effective diffusion barrier. Simulation results related to alternatives to Si dispersed in the Al matrix, such as the use of C coating of U-Mo particles or Zr instead of the Al matrix, are also shown. Recent experimental results confirmed early theoretical proposals, along the lines of the results reported in this work, showing that atomistic computational modeling could become a valuable tool to aid the experimental work in the development of nuclear fuels.« less

  7. High-Density Infrared Surface Treatments of Refractories

    SciTech Connect

    Tiegs, T.N.

    2005-03-31

    Refractory materials play a crucial role in all energy-intensive industries and are truly a crosscutting technology for the Industries of the Future (IOF). One of the major mechanisms for the degradation of refractories and a general decrease in their performance has been the penetration and corrosion by molten metals or glass. Methods and materials that would reduce the penetration, wetting, and corrosive chemistry would significantly improve refractory performance and also maintain the quality of the processed liquid, be it metal or glass. This report presents the results of an R&D project aimed at investigating the use of high-density infrared (HDI) heating to surface treat refractories to improve their performance. The project was a joint effort between Oak Ridge National Laboratory (ORNL) and the University of Missouri-Rolla (UMR). HDI is capable of heating the near-surface region of materials to very high temperatures where sintering, diffusion, and melting can occur. The intended benefits of HDI processing of refractories were to (1) reduce surface porosity (by essentially sealing the surface to prevent liquid penetration), (2) allow surface chemistry changes to be performed by bonding an adherent coating onto the underlying refractory (in order to inhibit wetting and/or improve corrosion resistance), and (3) produce noncontact refractories with high-emissivity surface coatings.

  8. [Residual risk: The roles of triglycerides and high density lipoproteins].

    PubMed

    Grammer, Tanja; Kleber, Marcus; Silbernagel, Günther; Scharnagl, Hubert; März, Winfried

    2016-06-01

    In clinical trials, the reduction of LDL-cholesterol (LDL-C) with statins reduces the incidence rate of cardiovascular events by approximately one third. This means, that a sizeable "residual risk" remains. Besides high lipoprotein (a), disorders in the metabolism of triglyceride-rich lipoproteins and high density liproteins have been implicated as effectors of the residual risk. Both lipoprotein parameters correlate inversely with each other. Therefore, the etiological contributions of triglycerides and / or of HDL for developing cardiovascular disease can hardly be estimated from either observational studies or from intervention studies. The largely disappointing results of intervention studies with inhibitors of the cholesteryl ester transfer protein and in particular the available set of genetically-epidemiological studies suggest that in the last decade, the importance of HDL cholesterol has been overvalued, while the importance of triglycerides has been underestimated. High triglycerides not always atherogenic, but only if they are associated with the accumulation relatively cholesterol-enriched, incompletely catabolized remnants of chylomicrons and very low density lipoproteins (familial type III hyperlipidemia, metabolic syndrome, diabetes mellitus). The normalization of the concentration of triglycerides and remnants by inhibiting the expression of apolipoprotein C3 is hence a new, promising therapeutic target.

  9. High-density matter: current status and future challenges

    NASA Astrophysics Data System (ADS)

    Stone, J. R.

    2015-05-01

    There are many fascinating processes in the Universe which we observe in more and more in detail thanks to increasingly sophisticated technology. One of the most interesting phenomena is the life cycle of stars, their birth, evolution and death. If the stars are massive enough, they end their lives in the core-collapse supernova explosion, the one of the most violent events in the Universe. As the result, the densest objects in the Universe, neutron stars and/or black holes are created. Naturally, the physical basis of these events should be understood in line with observation. The current status of our knowledge of processes in the life of stars is far from adequate for their true understanding. We show that although many models have been constructed their detailed ability to describe observations is limited or non-existent. Furthermore the general failure of all models means that we cannot tell which are heading in the right direction. A possible way forward in modeling of high-density matter is outlined, exemplified by the quark-meson-coupling model (QMC). This model has a natural explanation for the saturation of nuclear forces and depends on very few adjustable parameters, strongly constrained by the underlying physics. Latest QMC results for compact objects and finite nuclei are presented.

  10. A system verification platform for high-density epiretinal prostheses.

    PubMed

    Chen, Kuanfu; Lo, Yi-Kai; Yang, Zhi; Weiland, James D; Humayun, Mark S; Liu, Wentai

    2013-06-01

    Retinal prostheses have restored light perception to people worldwide who have poor or no vision as a consequence of retinal degeneration. To advance the quality of visual stimulation for retinal implant recipients, a higher number of stimulation channels is expected in the next generation retinal prostheses, which poses a great challenge to system design and verification. This paper presents a system verification platform dedicated to the development of retinal prostheses. The system includes primary processing, dual-band power and data telemetry, a high-density stimulator array, and two methods for output verification. End-to-end system validation and individual functional block characterization can be achieved with this platform through visual inspection and software analysis. Custom-built software running on the computers also provides a good way for testing new features before they are realized by the ICs. Real-time visual feedbacks through the video displays make it easy to monitor and debug the system. The characterization of the wireless telemetry and the demonstration of the visual display are reported in this paper using a 256-channel retinal prosthetic IC as an example.

  11. Path to Efficient Lower Hybrid Current Drive at High Density

    NASA Astrophysics Data System (ADS)

    Baek, S. G.; Bonoli, P. T.; Brunner, D.; Faust, I.; Labombard, B. L.; Parker, R. R.; Shiraiwa, S.; Wallace, G. M.; Wukitch, S.

    2015-11-01

    Recovery of lower hybrid current drive (LHCD) efficiency at high density was demonstrated on Alcator C-Mod by modifying the scrape-off layer (SOL) plasma. RF probe measurements around the C-Mod tokamak indicate that the LH wave amplitude at the high field side wall significantly attenuates with plasma density. This is interpreted as enhanced collisional loss due to the increase in the SOL density and width. By taking advantage of the narrower SOL width by doubling plasma current to 1.1 MA, it is found that the LH wave amplitude maintains its strength, and an effective current drive is extended to above 1x10e20 m-3. An order of magnitude increase in non-thermal Bremsstrahlung emission is consistent with ray-tracing results which take into account the change of SOL profiles with current. In the coming campaign, a further investigation on the role of the SOL plasma is planned by raising plasma current above 1.1 MA. This will be aided with newly developed RF magnetic loop antennas mounted on a radially movable probe head. This system is expected to intercept the LH resonance cone on the first pass, allowing us to measure radial profiles of both the wave amplitude and dominant parallel wavenumber in the SOL for the first time. These data will be compared with the GENRAY ray-tracing code. Work supported by USDoE awards DE-FC02-99ER54512.

  12. High-density lipoprotein exerts vasculoprotection via endothelial progenitor cells

    PubMed Central

    Petoumenos, Vasileios; Nickenig, Georg; Werner, Nikos

    2009-01-01

    Endothelial progenitor cells (EPC) enhance endothelial cell repair, improve endothelial dysfunction and are a predictor for cardiovascular mortality. High-density lipoprotein (HDL) cholesterol levels inversely correlate with cardiovascular events and have vasculoprotective effects. Here we postulate that HDL influences EPC biology. HDL and EPC were isolated according to standard procedures. Differentiation of mononuclear cells into DiLDL/lectin positive cells was enhanced after HDL treatment compared to vehicle. HDL was able to inhibit apoptosis (TUNEL assay, annexin V staining) while proliferation (BrdU incorporation) of early outgrowth colonies after extended cell cultivation (14 days) was increased. Flow chamber experiments revealed an improved adhesion of HDL pre-incubated EPC on human coronary artery endothelial cells (HCAEC) compared to vehicle while HDL treatment of HCAEC prevented adhesion of inflammatory cells. Flow cytometry demonstrated an up-regulation of β2- and α4-integrins on HDL pre-incubated EPC. Blocking experiments revealed a unique role of β2-integrin in EPC adhesion. Treatment of wild-type mice with recombinant HDL after endothelial denudation resulted in enhanced re-endothelialization compared to vehicle. Finally, in patients with coronary artery disease a correlation between circulating EPC and HDL concentrations was demonstrated. We provide evidence that HDL mediates important vasculoprotective action via the improvement of function of circulating EPC. PMID:18705697

  13. High-Density Superconducting Cables for Advanced ACTPol

    NASA Technical Reports Server (NTRS)

    Pappas, C. G.; Austermann, J.; Beall, J. A.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Henderson, S. W.; Ho, S. P.; Koopman, B. J.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Niraula, P.; Salatino, M.; Schillaci, A.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

    2016-01-01

    Advanced ACTPol (AdvACT) is an upcoming Atacama Cosmology Telescope (ACT) receiver upgrade, scheduled to deploy in 2016, that will allow measure- ment of the cosmic microwave background polarization and temperature to the highest precision yet with ACT. The AdvACT increase in sensitivity is partly provided by an increase in the number of transition-edge sensors (TESes) per array by up to a factor of two over the current ACTPol receiver detector arrays. The high-density AdvACT TES arrays require 70 µ m pitch superconducting flexible cables (flex) to connect the detec- tor wafer to the first-stage readout electronics. Here, we present the flex fabrication process and test results. For the flex wiring layer, we use a 400-nm-thick sputtered alu- minum film. In the center of the cable, the wiring is supported by a polyimide substrate, which smoothly transitions to a bare (uncoated with polyimide) silicon substrate at the ends of the cable for a robust wedge wire-bonding interface. Tests on the first batch of flex made for the first AdvACT array show that the flex will meet the requirements for AdvACT, with a superconducting critical current above 1 mA at 500 mK, resilience to mechanical and cryogenic stress, and a room temperature yield of 97%.

  14. A Concept for Robust, High Density Terminal Air Traffic Operations

    NASA Technical Reports Server (NTRS)

    Isaacson, Douglas R.; Robinson, John E.; Swenson, Harry N.; Denery, Dallas G.

    2010-01-01

    This paper describes a concept for future high-density, terminal air traffic operations that has been developed by interpreting the Joint Planning and Development Office s vision for the Next Generation (NextGen) Air Transportation System and coupling it with emergent NASA and other technologies and procedures during the NextGen timeframe. The concept described in this paper includes five core capabilities: 1) Extended Terminal Area Routing, 2) Precision Scheduling Along Routes, 3) Merging and Spacing, 4) Tactical Separation, and 5) Off-Nominal Recovery. Gradual changes are introduced to the National Airspace System (NAS) by phased enhancements to the core capabilities in the form of increased levels of automation and decision support as well as targeted task delegation. NASA will be evaluating these conceptual technological enhancements in a series of human-in-the-loop simulations and will accelerate development of the most promising capabilities in cooperation with the FAA through the Efficient Flows Into Congested Airspace Research Transition Team.

  15. Structural Stability and Functional Remodeling of High-Density Lipoproteins

    PubMed Central

    Gursky, Olga

    2015-01-01

    Lipoproteins are protein-lipid nanoparticles that transport lipids in circulation and are central in atherosclerosis and other disorders of lipid metabolism. Apolipoproteins form flexible structural scaffolds and important functional ligands on the particle surface and direct lipoprotein metabolism. Lipoproteins undergo multiple rounds of metabolic remodeling that is crucial to lipid transport. Important aspects of this remodeling, including apolipoprotein dissociation and particle fusion, are mimicked in thermal or chemical denaturation and are modulated by free energy barriers. Here we review our biophysical studies that revealed kinetic mechanism of lipoprotein stabilization and unraveled its structural basis. The main focus is on high-density lipoprotein (HDL). An inverse correlation between stability and functions of various HDLs in cholesterol transport suggests functional role of structural disorder. A mechanism for conformational adaptation of the major HDL proteins, apoA-I and apoA-II, to the increasing lipid load is proposed. Together, these studies help understand why HDL form discrete subclasses separated by kinetic barriers, which have distinct composition, conformation and functional properties. Understanding these properties may help improve HDL quality and develop novel therapies for cardiovascular disease. PMID:25749369

  16. High-Density Superconducting Cables for Advanced ACTPol

    NASA Astrophysics Data System (ADS)

    Pappas, C. G.; Austermann, J.; Beall, J. A.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Henderson, S. W.; Ho, S. P.; Koopman, B. J.; Li, D.; McMahon, J.; Nati, F.; Niemack, M. D.; Niraula, P.; Salatino, M.; Schillaci, A.; Schmitt, B. L.; Simon, S. M.; Staggs, S. T.; Stevens, J. R.; Vavagiakis, E. M.; Ward, J. T.; Wollack, E. J.

    2016-07-01

    Advanced ACTPol (AdvACT) is an upcoming Atacama Cosmology Telescope (ACT) receiver upgrade, scheduled to deploy in 2016, that will allow measurement of the cosmic microwave background polarization and temperature to the highest precision yet with ACT. The AdvACT increase in sensitivity is partly provided by an increase in the number of transition-edge sensors (TESes) per array by up to a factor of two over the current ACTPol receiver detector arrays. The high-density AdvACT TES arrays require 70 \\upmu m pitch superconducting flexible cables (flex) to connect the detector wafer to the first-stage readout electronics. Here, we present the flex fabrication process and test results. For the flex wiring layer, we use a 400-nm-thick sputtered aluminum film. In the center of the cable, the wiring is supported by a polyimide substrate, which smoothly transitions to a bare (uncoated with polyimide) silicon substrate at the ends of the cable for a robust wedge wire-bonding interface. Tests on the first batch of flex made for the first AdvACT array show that the flex will meet the requirements for AdvACT, with a superconducting critical current above 1 mA at 500 mK, resilience to mechanical and cryogenic stress, and a room temperature yield of 97 %.

  17. High-density lipoprotein (HDL) metabolism and bone mass.

    PubMed

    Papachristou, Nicholaos I; Blair, Harry C; Kypreos, Kyriakos E; Papachristou, Dionysios J

    2017-05-01

    It is well appreciated that high-density lipoprotein (HDL) and bone physiology and pathology are tightly linked. Studies, primarily in mouse models, have shown that dysfunctional and/or disturbed HDL can affect bone mass through many different ways. Specifically, reduced HDL levels have been associated with the development of an inflammatory microenvironment that affects the differentiation and function of osteoblasts. In addition, perturbation in metabolic pathways of HDL favors adipoblastic differentiation and restrains osteoblastic differentiation through, among others, the modification of specific bone-related chemokines and signaling cascades. Increased bone marrow adiposity also deteriorates bone osteoblastic function and thus bone synthesis, leading to reduced bone mass. In this review, we present the current knowledge and the future directions with regard to the HDL-bone mass connection. Unraveling the molecular phenomena that underline this connection will promote the deeper understanding of the pathophysiology of bone-related pathologies, such as osteoporosis or bone metastasis, and pave the way toward the development of novel and more effective therapies against these conditions. © 2017 Society for Endocrinology.

  18. Synthetic high-density lipoproteins for delivery of 10-hydroxycamptothecin

    PubMed Central

    Yuan, Yue; Wen, Jian; Tang, Jie; Kan, Qiming; Ackermann, Rose; Olsen, Karl; Schwendeman, Anna

    2016-01-01

    The purpose of this study was to develop a novel synthetic high-density lipoprotein (sHDL) nanoparticle delivery system for 10-hydroxycamptothecin (HCPT) for treatment of colon carcinoma. HDL is recognized by scavenger receptor B-I (SR-BI) over-expressed in colon carcinomas 5- to 35-fold relative to the human fibroblasts. The sHDL nanoparticles were composed of apolipoprotein A-I mimic peptide (5A) and contained 0.5%–1.5% (w/w) of HCPT. An optimized HCPT-sHDL formulation exhibited 0.7% HCPT loading with 70% efficiency with an average size of 10–12 nm. Partitioning of HCPT in the sHDL lipid membrane enhanced drug stability in its active lactone form, increased solubilization, and enabled slow release. Cytotoxicity studies in HT29 colon carcinoma cells revealed that the IC50 of HCPT-sHDL was approximately 3-fold lower than that of free HCPT. Pharmacokinetics in rats following intravenous administration showed that the area under the serum concentration-time curve (AUC0−t) and Cmax of HCPT-HDL were 2.7- and 6.5-fold higher relative to the values for the free HCPT, respectively. These results suggest that sHDL-based formulations of hydrophobic drugs are useful for future evaluation in treatment of SR-BI-positive tumors. PMID:27920529

  19. Iatrogenic severe depression of high-density lipoprotein cholesterol.

    PubMed

    Mymin, D; Dembinski, T; Friesen, M H

    2009-07-01

    The authors present 5 cases of paradoxical depression of high-density lipoprotein (HDL) cholesterol induced by fibrate drugs. In a 24-month review of all cases seen in one physician's practice at the Winnipeg Health Sciences Centre Lipid Clinic, 492 patients made a total of 1187 visits. Sixty-eight of them were given a fibrate drug (14%). Ten patients had HDL cholesterol levels that were less than 0.5 mmol/L (2%), and of these, 5 cases were due to exposure to fenofibrate (1%). These 5 cases comprised 7.4% of the 68 patients who were given any fibrate drug during that period. Mean levels were as follows: HDL cholesterol on fenofibrate 0.27, off fenofibrate 1.0 mmol/L and apo A1 on fenofibrate 0.41, off fenofibrate 1.17 g/L. A literature review revealed documented cases in 37 patients involving fibrates alone or in combination with other drugs known to cause decreased HDL cholesterol levels. In 13 patients, exposure was to fibrate therapy alone; in those exposed to combinations, the effect was clearly attributable to fibrates in 9; in 14, the nonfibrates (mostly rosiglitazone) were the attributable drugs; and in 1, it was impossible to tell. Thus, fibrate therapy should always be suspected as a cause of profoundly depressed HDL cholesterol.

  20. Outlier detection in high-density surface electromyographic signals.

    PubMed

    Marateb, Hamid R; Rojas-Martínez, Monica; Mansourian, Marjan; Merletti, Roberto; Villanueva, Miguel A Mañanas

    2012-01-01

    Recently developed techniques allow the analysis of surface EMG in multiple locations over the skin surface (high-density surface electromyography, HDsEMG). The detected signal includes information from a greater proportion of the muscle of interest than conventional clinical EMG. However, recording with many electrodes simultaneously often implies bad-contacts, which introduce large power-line interference in the corresponding channels, and short-circuits that cause near-zero single differential signals when using gel. Such signals are called 'outliers' in data mining. In this work, outlier detection (focusing on bad contacts) is discussed for monopolar HDsEMG signals and a new method is proposed to identify 'bad' channels. The overall performance of this method was tested using the agreement rate against three experts' opinions. Three other outlier detection methods were used for comparison. The training and test sets for such methods were selected from HDsEMG signals recorded in Triceps and Biceps Brachii in the upper arm and Brachioradialis, Anconeus, and Pronator Teres in the forearm. The sensitivity and specificity of this algorithm were, respectively, 96.9 ± 6.2 and 96.4 ± 2.5 in percent in the test set (signals registered with twenty 2D electrode arrays corresponding to a total of 2322 channels), showing that this method is promising.

  1. A new technology for high density actuator arrays

    NASA Astrophysics Data System (ADS)

    Bowles, Adrian; Rahman, Ahmed; Jarman, Tim; Morris, Paul; Gore, Jon

    2005-05-01

    A new, low cost technique for excitation and control of high density, actuator arrays has been developed. Primarily aimed at the tactile display of universal text, Braille and graphics for the Blind community, magnetic forces are utilised to actuate and hold individually addressable pins. Current tactile displays that allow Blind people to interact with the world via electronic media are expensive and due to their inherent complexity can only display the Braille language, which on average only 10% of visually impaired people in Western society are able to read. There is a need for a more flexible communication device. Using multilayer printed circuit board techniques to minimize production and assembly costs, large arrays of magnetic solenoid actuators were fabricated on a single substrate. They were electrically interconnected to allow matrix addressing of any single element in the array to reduce electronic component count. A bistable mechanism was produced using a permanent magnet layer allowing the solenoid actuator to be toggled between an 'up' state and a 'down' state. Besides being necessary for matrix addressing, this bistability gives good energy efficiency as power is only required when the system is updated and not when holding the static display. An error correction technique was developed that automatically corrected a bistable actuator if it had mistakenly moved into an incorrect position through mechanical shock. A 360 actuator demonstration unit was produced that displayed alphanumeric text, Braille or graphics in a tactile form.

  2. Acrolein impairs the cholesterol transport functions of high density lipoproteins.

    PubMed

    Chadwick, Alexandra C; Holme, Rebecca L; Chen, Yiliang; Thomas, Michael J; Sorci-Thomas, Mary G; Silverstein, Roy L; Pritchard, Kirkwood A; Sahoo, Daisy

    2015-01-01

    High density lipoproteins (HDL) are considered athero-protective, primarily due to their role in reverse cholesterol transport, where they transport cholesterol from peripheral tissues to the liver for excretion. The current study was designed to determine the impact of HDL modification by acrolein, a highly reactive aldehyde found in high abundance in cigarette smoke, on the cholesterol transport functions of HDL. HDL was chemically-modified with acrolein and immunoblot and mass spectrometry analyses confirmed apolipoprotein crosslinking, as well as acrolein adducts on apolipoproteins A-I and A-II. The ability of acrolein-modified HDL (acro-HDL) to serve as an acceptor of free cholesterol (FC) from COS-7 cells transiently expressing SR-BI was significantly decreased. Further, in contrast to native HDL, acro-HDL promotes higher neutral lipid accumulation in murine macrophages as judged by Oil Red O staining. The ability of acro-HDL to mediate efficient selective uptake of HDL-cholesteryl esters (CE) into SR-BI-expressing cells was reduced compared to native HDL. Together, the findings from our studies suggest that acrolein modification of HDL produces a dysfunctional particle that may ultimately promote atherogenesis by impairing functions that are critical in the reverse cholesterol transport pathway.

  3. Stability of discoidal high-density lipoprotein particles

    NASA Astrophysics Data System (ADS)

    Maleki, Mohsen; Fried, Eliot

    Motivated by experimental and numerical studies revealing that discoidal high-density lipoprotein (HDL) particles may adopt flat elliptical and nonplanar saddle-like configurations, it is hypothesized that these might represent stabilized configurations of initially unstable flat circular particles. A variational description is developed to explore the stability of a flat circular discoidal HDL particle. While the lipid bilayer is modeled as two-dimensional fluid film endowed with surface tension and bending elasticity, the apoA-I belt is modeled as one-dimensional inextensible twist-free chain endowed with bending elasticity. Stability is investigated using the second variation of the underlying energy functional. Various planar and nonplanar instability modes are predicted and corresponding nondimensional critical values of salient dimensionless parameters are obtained. The results predict that the first planar and nonplanar unstable modes occur due to in-plane elliptical and transverse saddle-like perturbations. Based on available data, detailed stability diagrams indicate the range of input parameters for which a flat circular discoidal HDL particle is linearly stable or unstable.

  4. Patterned Platinum Etching Studies in an Argon High Density Plasma

    NASA Astrophysics Data System (ADS)

    Delprat, Sébastien; Chaker, Mohamed; Margot, Joëlle; Pépin, Henri; Tan, Liang; Smy, Tom

    1998-10-01

    A high-density surface-wave Ar plasma operated in the low pressure regime is used to study pure physical etching characteristics of platinum thin films. The platinum samples are RF biased so as to obtain a maximum DC self-bias voltage of 150 V. The sputter-etching characteristics are investigated as a function of the magnetic field intensity, the self-bias voltage and the gas pressure. At 1 mtorr, the etch rate is found to be a unique linear function of both the self-bias voltage and the ion density, independently of the magnetic field intensity value. However, even though the ion density increases, the etch rate is found to decrease with increasing pressure. In the low pressure regime, etch rates as high as 2000 A/min are obtained with a good selectivity over resist. Without any optimization of the etching process, we were able to etch 0.5 micron Pt trenches, 0.6 micron thick yielding fence-free profiles and sidewall angles (75º) that already meets the present industrial requirements of NVRAM technology.

  5. Characterizing uncertainty in high-density maps from multiparental populations.

    PubMed

    Ahfock, Daniel; Wood, Ian; Stephen, Stuart; Cavanagh, Colin R; Huang, B Emma

    2014-09-01

    Multiparental populations are of considerable interest in high-density genetic mapping due to their increased levels of polymorphism and recombination relative to biparental populations. However, errors in map construction can have significant impact on QTL discovery in later stages of analysis, and few methods have been developed to quantify the uncertainty attached to the reported order of markers or intermarker distances. Current methods are computationally intensive or limited to assessing uncertainty only for order or distance, but not both simultaneously. We derive the asymptotic joint distribution of maximum composite likelihood estimators for intermarker distances. This approach allows us to construct hypothesis tests and confidence intervals for simultaneously assessing marker-order instability and distance uncertainty. We investigate the effects of marker density, population size, and founder distribution patterns on map confidence in multiparental populations through simulations. Using these data, we provide guidelines on sample sizes necessary to map markers at sub-centimorgan densities with high certainty. We apply these approaches to data from a bread wheat Multiparent Advanced Generation Inter-Cross (MAGIC) population genotyped using the Illumina 9K SNP chip to assess regions of uncertainty and validate them against the recently released pseudomolecule for the wheat chromosome 3B. Copyright © 2014 by the Genetics Society of America.

  6. High-Density Superconducting Cables for Advanced ACTPol

    NASA Technical Reports Server (NTRS)

    Pappas, C. G.; Austermann, J.; Beall, J. A.; Duff, S. M.; Gallardo, P. A.; Grace, E.; Henderson, S. W.; Ho, S. P.; Koopman, B. J.; Li, D.; hide

    2016-01-01

    Advanced ACTPol (AdvACT) is an upcoming Atacama Cosmology Telescope (ACT) receiver upgrade, scheduled to deploy in 2016, that will allow measure- ment of the cosmic microwave background polarization and temperature to the highest precision yet with ACT. The AdvACT increase in sensitivity is partly provided by an increase in the number of transition-edge sensors (TESes) per array by up to a factor of two over the current ACTPol receiver detector arrays. The high-density AdvACT TES arrays require 70 µ m pitch superconducting flexible cables (flex) to connect the detec- tor wafer to the first-stage readout electronics. Here, we present the flex fabrication process and test results. For the flex wiring layer, we use a 400-nm-thick sputtered alu- minum film. In the center of the cable, the wiring is supported by a polyimide substrate, which smoothly transitions to a bare (uncoated with polyimide) silicon substrate at the ends of the cable for a robust wedge wire-bonding interface. Tests on the first batch of flex made for the first AdvACT array show that the flex will meet the requirements for AdvACT, with a superconducting critical current above 1 mA at 500 mK, resilience to mechanical and cryogenic stress, and a room temperature yield of 97%.

  7. New electrode-barrier structures for high density ferroelectric memories

    NASA Astrophysics Data System (ADS)

    Vedula, R.; Desu, C. S.; Tirumala, S.; Bhatt, H. D.; Desu, S. B.; Lee, K. B.

    2001-03-01

    In this paper, two electrode-barrier structures based on Pt-Rh and Pt-Ir alloys and their oxides are proposed for high-density ferroelectric memory applications. These electrode-barriers are multi-layered, comprising a diffusion barrier (PtRhOx or PtIrOx), metal alloy (PtRh or PtIr) and another PtRhOx or PtIrOx layer for fatigue reduction in the case of PZT capacitors. Both lead zirconate titanate (PZT) and strontium bismuth tantalate (SBT) capacitors based on the electrode-barriers were used in the present study. The electrode-barrier structure acts as a conducting electrode as well as an excellent diffusion barrier for lead, bismuth, oxygen and silicon. The PZT test capacitors fabricated on these electrode-barriers showed excellent fatigue resistance with other ferroelectric properties being similar to those on Pt. Also, these electrode-barriers are stable, and remain conductive even up to the processing temperatures of SBT (750 °C). This makes direct integration of both PZT and SBT capacitors on to a poly-Si plug attainable. In addition, the conducting electrode-barrier structures can be deposited in situ, directly over n+polycrystalline Si, thereby significantly improving the density of the device.

  8. High density operation with Lower Hybrid waves in FTU tokamak

    NASA Astrophysics Data System (ADS)

    Pericoli Ridolfini, V.; Mirizzi, F.; Panaccione, L.; Podda, S.

    2001-10-01

    Since April 2001 the lower hybrid (LH) radiofrequency system in FTU (6 gyrotrons @ f=8 GHz) can deliver to the plasma about 2 MW through two equal launchers with a reflection coefficient = 10%. This value is close to the target value of 2.2 MW (net power density of 6.2 kW/cm2 on the waveguides mouth) which could be reached after further conditioning of the grill and of the transmission lines. In high density plasmas (line density *1*1020 m-3), high magnetic field (BT=7.2 T), with PLH=2 MW we drive about 75% of the total current (Ip=500 kA) and stabilise fully the sawteeth activity. The central electron temperature Te0 increases from 1.6 to 3.3 keV (steady), and the neutron rate by about 10 times. Analysis of these pulses with effective electronic heating will be presented. In post-pellet plasmas ( *6*1020 m-3), good coupling of the LH is achieved with the launcher almost flush to the walls, due to the very dense scrape off-layer. The perturbation here induced by the pellet imposes a delay to the LH of only 20 ms. The exact location of the launcher is critical in these regimes, because the high N|| (parallel index of refraction) requested (N||>2.3) for a good penetration of the waves makes more problematic a good coupling all along the poloidal extension of the grill.

  9. High-density lipoprotein-raising strategies: update 2010.

    PubMed

    Spillmann, Frank; Schultheiss, Heinz-Peter; Tschöpe, Carsten; Van Linthout, Sophie

    2010-05-01

    Population studies have consistently shown that high-density lipoprotein (HDL) cholesterol levels are a strong, independent inverse predictor of cardiovascular disease. Every 1 mg/dl increase in HDL cholesterol is associated with a 2% to 3% decrease in coronary artery disease risk, independent of low-density lipoprotein (LDL) cholesterol and triglyceride levels. The primary mechanism for this protective effect is believed to be reverse cholesterol transport, but several other anti-inflammatory, anti-apoptotic, anti-oxidative functions for HDL have also been identified. Low HDL cholesterol is predictive of cardiovascular events in statin-treated patients with low LDL cholesterol, indicating that intensive lipid lowering strategies with statins alone are not sufficient to prevent cardiovascular events, and merging for additional effective HDL-raising therapy. This review focuses at giving an overview of current established HDL-raising pharmaca, including statins, fibrates, thiazolidinediones, and nicotinic acids, and of novel therapies including cholesterol ester transfer protein-inhibitors, liver X receptor agonists, reconstituted HDL, and apolipoprotein A-I mimetics. Working mechanisms are described and results from clinical trials of monotherapy and combination therapy are discussed.

  10. Crystallographic alignment of high-density gallium nitride nanowire arrays.

    PubMed

    Kuykendall, Tevye; Pauzauskie, Peter J; Zhang, Yanfeng; Goldberger, Joshua; Sirbuly, Donald; Denlinger, Jonathan; Yang, Peidong

    2004-08-01

    Single-crystalline, one-dimensional semiconductor nanostructures are considered to be one of the critical building blocks for nanoscale optoelectronics. Elucidation of the vapour-liquid-solid growth mechanism has already enabled precise control over nanowire position and size, yet to date, no reports have demonstrated the ability to choose from different crystallographic growth directions of a nanowire array. Control over the nanowire growth direction is extremely desirable, in that anisotropic parameters such as thermal and electrical conductivity, index of refraction, piezoelectric polarization, and bandgap may be used to tune the physical properties of nanowires made from a given material. Here we demonstrate the use of metal-organic chemical vapour deposition (MOCVD) and appropriate substrate selection to control the crystallographic growth directions of high-density arrays of gallium nitride nanowires with distinct geometric and physical properties. Epitaxial growth of wurtzite gallium nitride on (100) gamma-LiAlO(2) and (111) MgO single-crystal substrates resulted in the selective growth of nanowires in the orthogonal [1\\[Evec]0] and [001] directions, exhibiting triangular and hexagonal cross-sections and drastically different optical emission. The MOCVD process is entirely compatible with the current GaN thin-film technology, which would lead to easy scale-up and device integration.

  11. Enhanced configurational entropy in high-density nanoconfined bilayer ice

    NASA Astrophysics Data System (ADS)

    Corsetti, Fabiano; Zubeltzu, Jon; Artacho, Emilio

    Understanding the structural tendencies of nanoconfined water is of great interest for nanoscience and biology, where nano/micro-sized objects may be separated by very few layers of water. We present a study of water confined to a 2D geometry by a featureless, chemically neutral potential, in order to characterize its intrinsic behaviour. We use molecular dynamics simulations with the TIP4P/2005 potential, combined with density-functional theory calculations with a non-local van der Waals density functional and an ab initio random structure search procedure. We propose a novel kind of crystal order in high-density nanoconfined bilayer ice. A first-order transition is observed between a low-temperature proton-ordered solid and a high-temperature proton-disordered solid. The latter is shown to possess crystalline order for the oxygen positions, arranged on a close-packed triangular lattice with AA stacking. Uniquely amongst the ice phases, the triangular bilayer is characterized by two levels of disorder (for the bonding network and for the protons) which results in a configurational entropy twice that of bulk ice.

  12. Gene expression profiling in peanut using high density oligonucleotide microarrays

    PubMed Central

    Payton, Paxton; Kottapalli, Kameswara Rao; Rowland, Diane; Faircloth, Wilson; Guo, Baozhu; Burow, Mark; Puppala, Naveen; Gallo, Maria

    2009-01-01

    Background Transcriptome expression analysis in peanut to date has been limited to a relatively small set of genes and only recently has a significant number of ESTs been released into the public domain. Utilization of these ESTs for oligonucleotide microarrays provides a means to investigate large-scale transcript responses to a variety of developmental and environmental signals, ultimately improving our understanding of plant biology. Results We have developed a high-density oligonucleotide microarray for peanut using 49,205 publicly available ESTs and tested the utility of this array for expression profiling in a variety of peanut tissues. To identify putatively tissue-specific genes and demonstrate the utility of this array for expression profiling in a variety of peanut tissues, we compared transcript levels in pod, peg, leaf, stem, and root tissues. Results from this experiment showed 108 putatively pod-specific/abundant genes, as well as transcripts whose expression was low or undetected in pod compared to peg, leaf, stem, or root. The transcripts significantly over-represented in pod include genes responsible for seed storage proteins and desiccation (e.g., late-embryogenesis abundant proteins, aquaporins, legumin B), oil production, and cellular defense. Additionally, almost half of the pod-abundant genes represent unknown genes allowing for the possibility of associating putative function to these previously uncharacterized genes. Conclusion The peanut oligonucleotide array represents the majority of publicly available peanut ESTs and can be used as a tool for expression profiling studies in diverse tissues. PMID:19523230

  13. Diagnosis and Treatment of High Density Lipoprotein Deficiency

    PubMed Central

    Schaefer, Ernst J.; Anthanont, Pimjai; Diffenderfer, Margaret R.; Polisecki, Eliana; Asztalos, Bela F.

    2017-01-01

    Low serum high density lipoprotein cholesterol level (HDL-C) < 40 mg/dL in men and < 50 mg/dL in women are a significant independent risk factor for cardiovascular disease (CVD), and are often observed in patients with hypertriglyceridemia, obesity, insulin resistance, and diabetes. Patients with marked deficiency of HDL-C (< 20 mg/dL) in the absence of secondary causes are much less common (< 1% of the population). These patients may have homozygous, compound heterozygous, or heterozygous defects involving the apolipoprotein (APO)AI, ABCA1, or lecithin:cholesterol acyl transferase genes, associated with Apo A-I Deficiency, ApoA-I Variants, Tangier Disease, Familial Lecithin:Cholesteryl Ester Acyltransferase Deficiency, and Fish Eye Disease. There is marked variability in laboratory and clinical presentation, and DNA analysis is necessary for diagnosis. These patients can develop premature CVD, neuropathy, kidney failure, neuropathy, hepatosplenomegaly and anemia. Treatment should be directed at optimizing all non-HDL risk factors. PMID:27565770

  14. High-Density Carbon (HDC) Ablator for NIC Ignition Capsules

    NASA Astrophysics Data System (ADS)

    Ho, D.; Haan, S.; Salmonson, J.; Milovich, J.; Callahan, D.

    2012-10-01

    HDC ablators show high performance based on simulations, despite the fact that the shorter pulses for HDC capsules result in higher M-band radiation compared to that for plastic capsules. HDC capsules have good 1-D performance because HDC has relatively high density (3.5 g/cc), which results in a thinner ablator that absorbs more radiation. HDC ablators have good 2-D performance because the ablator surface is more than an order-of-magnitude smoother than Be or plastic ablators. Refreeze of the ablator near the fuel region can be avoided by appropriate dopant placement. Here we present two HDC ignition designs doped with W and Si. For the design with maximum W concentration of 1.0 at% (and respectively with maximum Si concentration of 2.0 at%): peak velocity = 0.395 (0.397) mm/ns, mass weighted fuel entropy = 0.463 (0.469) kJ/mg/eV, peak core hydrodynamic stagnation pressure = 690 (780) Gbar, and yield = 17.3 (20.2) MJ. 2-D simulations show that yield is close to 80% YoC even with 2.5x of nominal surface roughness on all surfaces. The clean fuel fraction is about 75% at peak velocity. Doping HDC with the required concentration of W and Si is in progress. A first undoped HDC Symcap is scheduled to be fielded later this year.

  15. STEM-EELS analysis reveals stable high-density He in nanopores of amorphous silicon coatings deposited by magnetron sputtering.

    PubMed

    Schierholz, Roland; Lacroix, Bertrand; Godinho, Vanda; Caballero-Hernández, Jaime; Duchamp, Martial; Fernández, Asunción

    2015-02-20

    A broad interest has been showed recently on the study of nanostructuring of thin films and surfaces obtained by low-energy He plasma treatments and He incorporation via magnetron sputtering. In this paper spatially resolved electron energy-loss spectroscopy in a scanning transmission electron microscope is used to locate and characterize the He state in nanoporous amorphous silicon coatings deposited by magnetron sputtering. A dedicated MATLAB program was developed to quantify the helium density inside individual pores based on the energy position shift or peak intensity of the He K-edge. A good agreement was observed between the high density (∼35-60 at nm(-3)) and pressure (0.3-1.0 GPa) values obtained in nanoscale analysis and the values derived from macroscopic measurements (the composition obtained by proton backscattering spectroscopy coupled to the macroscopic porosity estimated from ellipsometry). This work provides new insights into these novel porous coatings, providing evidence of high-density He located inside the pores and validating the methodology applied here to characterize the formation of pores filled with the helium process gas during deposition. A similar stabilization of condensed He bubbles has been previously demonstrated by high-energy He ion implantation in metals and is newly demonstrated here using a widely employed methodology, magnetron sputtering, for achieving coatings with a high density of homogeneously distributed pores and He storage capacities as high as 21 at%.

  16. Experimental study of high density foods for the Space Operations Center

    NASA Technical Reports Server (NTRS)

    Ahmed, S. M.

    1981-01-01

    The experimental study of high density foods for the Space Operations Center is described. A sensory evaluation of the high density foods was conducted first to test the acceptability of the products. A shelf-life study of the high density foods was also conducted for three different time lengths at three different temperatures. The nutritional analysis of the high density foods is at present incomplete.

  17. Experimental study of high density foods for the Space Operations Center

    NASA Technical Reports Server (NTRS)

    Ahmed, S. M.

    1981-01-01

    The experimental study of high density foods for the Space Operations Center is described. A sensory evaluation of the high density foods was conducted first to test the acceptability of the products. A shelf-life study of the high density foods was also conducted for three different time lengths at three different temperatures. The nutritional analysis of the high density foods is at present incomplete.

  18. High density 3D printed microfluidic valves, pumps, and multiplexers.

    PubMed

    Gong, Hua; Woolley, Adam T; Nordin, Gregory P

    2016-07-07

    In this paper we demonstrate that 3D printing with a digital light processor stereolithographic (DLP-SLA) 3D printer can be used to create high density microfluidic devices with active components such as valves and pumps. Leveraging our previous work on optical formulation of inexpensive resins (RSC Adv., 2015, 5, 106621), we demonstrate valves with only 10% of the volume of our original 3D printed valves (Biomicrofluidics, 2015, 9, 016501), which were already the smallest that have been reported. Moreover, we show that incorporation of a thermal initiator in the resin formulation along with a post-print bake can dramatically improve the durability of 3D printed valves up to 1 million actuations. Using two valves and a valve-like displacement chamber (DC), we also create compact 3D printed pumps. With 5-phase actuation and a 15 ms phase interval, we obtain pump flow rates as high as 40 μL min(-1). We also characterize maximum pump back pressure (i.e., maximum pressure the pump can work against), maximum flow rate (flow rate when there is zero back pressure), and flow rate as a function of the height of the pump outlet. We further demonstrate combining 5 valves and one DC to create a 3-to-2 multiplexer with integrated pump. In addition to serial multiplexing, we also show that the device can operate as a mixer. Importantly, we illustrate the rapid fabrication and test cycles that 3D printing makes possible by implementing a new multiplexer design to improve mixing, and fabricate and test it within one day.

  19. Isolation of high density lipoproteins from rat intestinal epithelial cells.

    PubMed Central

    Magun, A M; Brasitus, T A; Glickman, R M

    1985-01-01

    Previous studies have defined forms of high density lipoproteins (HDL) in rat mesenteric lymph, suggesting that they have a secretory origin. This study describes the isolation and characterization of intestinal intracellular HDL. Two preparations were made as follows: (a) Rat enterocytes were isolated and a Golgi organelle fraction was prepared. (b) Cell homogenates were subjected to nitrogen cavitation and a cytoplasmic fraction was prepared. Lipoproteins were isolated from both preparations by sequential ultracentrifugation. When the HDL fraction (1.07-1.21 g/ml) was subjected to isopyknic density gradient ultracentrifugation, a peak of apoproteins A-I and B (apoA-I and apoB, respectively) was found at a density of 1.11-1.14 g/ml. Electron microscopy of the fraction showed spherical particles ranging in size from 6 to 13 nm. Immunoelectrophoresis revealed a precipitin arc in the alpha region against apoA-I which extended into the pre-beta region where a precipitin arc against apoB was also seen. ApoB antisera depleted the pre-beta particles whereas the alpha migrating particles remained. Lipid analysis of the whole HDL fraction revealed phospholipid, cholesteryl ester, and triglyceride as the major lipids. [3H]leucine was then administered into the duodenum and a radiolabeled intracellular HDL fraction was isolated. The newly synthesized apoproteins of the HDL fraction, as determined by gel electrophoresis, were apoB, apoA-I, and apolipoprotein A-IV (ApoA-IV). Immunoprecipitation of the apoB particles revealed apoA-I and apoA-IV in the supernatant. These data demonstrate that there are at least two intracellular intestinal forms of HDL particles, one of which contains apoB. The other particle contains apoA-I and apoA-IV, has alpha mobility, is spherical, and resembles a particle found in the lymph. Images PMID:3965504

  20. Distribution of High-Density Lipoprotein Subfractions and Hypertensive Status

    PubMed Central

    Zhang, Yan; Li, Sha; Xu, Rui-Xia; Guo, Yuan-Lin; Wu, Na-Qiong; Zhu, Cheng-Gang; Gao, Ying; Dong, Qian; Liu, Geng; Sun, Jing; Li, Jian-Jun

    2015-01-01

    Abstract The exact mechanisms of hypertension contributing to atherosclerosis have not been fully elucidated. Although multiple studies have clarified the association with low-density lipoprotein (LDL) subfractions, uncertainty remains about its relationship with high-density lipoprotein (HDL) subfractions. Therefore, we aimed to comprehensively determine the relationship between distribution of HDL subfractions and hypertensive status. A total of 953 consecutive subjects without previous lipid-lowering drug treatment were enrolled and were categorized based on hypertension history (with hypertension [n = 550] or without hypertension [n = 403]). Baseline clinical and laboratory data were collected. HDL separation was performed using the Lipoprint System. Plasma large HDL-cholesterol (HDL-C) and large HDL percentage were dramatically lower whereas the small HDL-C and small HDL percentage were higher in patients with hypertension (all P < 0.05). The antihypertensive drug therapy was not associated with large or small HDL subfractions (on treatment vs not on treatment, P > 0.05; combination vs single drug therapy, P > 0.05). However, the blood pressure well-controlled patients have significantly lower small HDL subfraction (P < 0.05). Moreover, large HDL-C and percentage were inversely whereas small HDL percentage was positively associated with incident hypertension after adjusting potential confounders (all P < 0.05). In the multivariate model conducted in patients with and without hypertension separately, the cardio-protective value of large HDL-C was disappeared in patients with hypertension (OR 95%CI: 1.011 [0.974–1.049]). The distribution of HDL subfractions is closely associated with hypertensive status and hypertension may potentially impact the cardio-protective value of large HDL subfraction. PMID:26512616

  1. Surface interactions involved in flashover with high density electronegative gases.

    SciTech Connect

    Hodge, Keith Conquest; Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Wallace, Zachariah Red; Lehr, Jane Marie

    2010-01-01

    This report examines the interactions involved with flashover along a surface in high density electronegative gases. The focus is on fast ionization processes rather than the later time ionic drift or thermalization of the discharge. A kinetic simulation of the gas and surface is used to examine electron multiplication and includes gas collision, excitation and ionization, and attachment processes, gas photoionization and surface photoemission processes, as well as surface attachment. These rates are then used in a 1.5D fluid ionization wave (streamer) model to study streamer propagation with and without the surface in air and in SF6. The 1.5D model therefore includes rates for all these processes. To get a better estimate for the behavior of the radius we have studied radial expansion of the streamer in air and in SF6. The focus of the modeling is on voltage and field level changes (with and without a surface) rather than secondary effects, such as, velocities or changes in discharge path. An experiment has been set up to carry out measurements of threshold voltages, streamer velocities, and other discharge characteristics. This setup includes both electrical and photographic diagnostics (streak and framing cameras). We have observed little change in critical field levels (where avalanche multiplication sets in) in the gas alone versus with the surface. Comparisons between model calculations and experimental measurements are in agreement with this. We have examined streamer sustaining fields (field which maintains ionization wave propagation) in the gas and on the surface. Agreement of the gas levels with available literature is good and agreement between experiment and calculation is good also. Model calculations do not indicate much difference between the gas alone versus the surface levels. Experiments have identified differences in velocity between streamers on the surface and in the gas alone (the surface values being larger).

  2. High density scalp EEG in frontal lobe epilepsy.

    PubMed

    Feyissa, Anteneh M; Britton, Jeffrey W; Van Gompel, Jamie; Lagerlund, Terrance L; So, Elson; Wong-Kisiel, Lilly C; Cascino, Gregory C; Brinkman, Benjamin H; Nelson, Cindy L; Watson, Robert; Worrell, Gregory A

    2017-01-01

    Localization of seizures in frontal lobe epilepsy using the 10-20 system scalp EEG is often challenging because neocortical seizure can spread rapidly, significant muscle artifact, and the suboptimal spatial resolution for seizure generators involving mesial frontal lobe cortex. Our aim in this study was to determine the value of visual interpretation of 76 channel high density EEG (hdEEG) monitoring (10-10 system) in patients with suspected frontal lobe epilepsy, and to evaluate concordance with MRI, subtraction ictal SPECT co-registered to MRI (SISCOM), conventional EEG, and intracranial EEG (iEEG). We performed a retrospective cohort study of 14 consecutive patients who underwent hdEEG monitoring for suspected frontal lobe seizures. The gold standard for localization was considered to be iEEG. Concordance of hdEEG findings with MRI, subtraction ictal SPECT co-registered to MRI (SISCOM), conventional 10-20 EEG, and iEEG as well as correlation of hdEEG localization with surgical outcome were examined. hdEEG localization was concordant with iEEG in 12/14 and was superior to conventional EEG 3/14 (p<0.01) and SISCOM 3/12 (p<0.01). hdEEG correctly lateralized seizure onset in 14/14 cases, compared to 9/14 (p=0.04) cases with conventional EEG. Seven patients underwent surgical resection, of whom five were seizure free. hdEEG monitoring should be considered in patients with suspected frontal epilepsy requiring localization of epileptogenic brain. hdEEG may assist in developing a hypothesis for iEEG monitoring and could potentially augment EEG source localization. Published by Elsevier B.V.

  3. Proprotein convertases in high-density lipoprotein metabolism.

    PubMed

    Choi, Seungbum; Korstanje, Ron

    2013-09-18

    The proprotein convertase subtilisin/kexins (PCSKs) are a serine endopeptidase family. PCSK members cleave amino acid residues and modulate the activity of precursor proteins. Evidence from patients and animal models carrying genetic alterations in PCSK members show that PCSK members are involved in various metabolic processes. These studies further revealed the molecular mechanism by which genetic alteration of some PCSK members impairs normal molecular and physiological functions, which in turn lead to cardiovascular disease. High-density lipoprotein (HDL) is anti-atherogenic as it removes excessive amount of cholesterol from blood and peripheral tissues. Several PCSK members are involved in HDL metabolism. PCSK3, PCSK5, and PCSK6 process two triglyceride lipase family members, endothelial lipase and lipoprotein lipase, which are important for HDL remodeling. Recent studies in our lab found evidence that PCSK1 and PCSK9 are also involved in HDL metabolism. A mouse model carrying an amino acid substitution in PCSK1 showed an increase in serum apolipoprotein A1 (APOA1) level. Another mouse model lacking PCSK9 showed a decrease in APOE-containing HDL. In this review, we summarize the role of the five PCSK members in lipid, glucose, and bile acid (BA) metabolism, each of which can influence HDL metabolism. We propose an integrative model in which PCSK members regulate HDL metabolism through various molecular mechanisms and metabolic processes and genetic variation in some PCSK members may affect the efficiency of reverse cholesterol transport. PCSK members are considered as attractive therapeutic targets. A greater understanding of the molecular and physiological functions of PCSK members will improve therapeutic strategies and drug efficacy for cardiovascular disease where PCSK members play critical role, with fewer adverse effects.

  4. High-density fluids and the growth of monocrystalline diamonds

    NASA Astrophysics Data System (ADS)

    Weiss, Y.; Kiflawi, I.; Davies, N.; Navon, O.

    2014-09-01

    The chemical nature and composition of the growth medium of monocrystalline (MC) diamonds is still a matter of debate, partially because carbonate-bearing high-density fluids (HDFs) that are common in fibrous diamonds have not been found in MC diamonds. Here we report the first finding of HDF microinclusions in a MC octahedral diamond from Finsch, South Africa and in the MC octahedral core of a coated diamond from Kankan, Guinea; both diamonds carry nitrogen in B-centers. Numerous microinclusions in diamond Finsch_2a_cap1 are restricted to two thin layers parallel to the (1 1 1) face, ∼20 and 200 μm from the diamond rim. Low-Mg carbonatitic HDFs are found along the inner layer while the outer layer trapped saline compositions. The major and trace element compositions of the inclusions and their infrared spectra are highly similar to those of microinclusions found in fibrous diamonds. A few isolated microinclusions of saline compositions are scattered around a sulfide inclusion in the center of the octahedral core of diamond ON-KAN-383. This evidence for the involvement of oxidized fluids in the formation of MC diamonds adds to previous reports on the antiquity of HDFs in fibrous diamonds, the presence of carbonate and halide phases in inclusions in MC diamonds and the similarity of trace element pattern of a MC diamond to those of low-Mg carbonatitic HDF in fibrous diamonds. In addition, we show that the interaction of HDFs with depleted garnets can produce sinusoidal REE patterns which are one of the primary features of lherzolitic and harzburgitic garnet inclusions in MC diamonds. Together, these observations suggest that HDFs are involved in the formation of many types of diamonds from the Archaean to the Phanerozoic. HDFs are trapped in large quantities during rapid, fibrous growth, but must also be present during the growth of many MC diamonds.

  5. Differential analysis for high density tiling microarray data.

    PubMed

    Ghosh, Srinka; Hirsch, Heather A; Sekinger, Edward A; Kapranov, Philipp; Struhl, Kevin; Gingeras, Thomas R

    2007-09-24

    High density oligonucleotide tiling arrays are an effective and powerful platform for conducting unbiased genome-wide studies. The ab initio probe selection method employed in tiling arrays is unbiased, and thus ensures consistent sampling across coding and non-coding regions of the genome. These arrays are being increasingly used to study the associated processes of transcription, transcription factor binding, chromatin structure and their association. Studies of differential expression and/or regulation provide critical insight into the mechanics of transcription and regulation that occurs during the developmental program of a cell. The time-course experiment, which comprises an in-vivo system and the proposed analyses, is used to determine if annotated and un-annotated portions of genome manifest coordinated differential response to the induced developmental program. We have proposed a novel approach, based on a piece-wise function - to analyze genome-wide differential response. This enables segmentation of the response based on protein-coding and non-coding regions; for genes the methodology also partitions differential response with a 5' versus 3' versus intra-genic bias. The algorithm built upon the framework of Significance Analysis of Microarrays, uses a generalized logic to define regions/patterns of coordinated differential change. By not adhering to the gene-centric paradigm, discordant differential expression patterns between exons and introns have been identified at a FDR of less than 12 percent. A co-localization of differential binding between RNA Polymerase II and tetra-acetylated histone has been quantified at a p-value < 0.003; it is most significant at the 5' end of genes, at a p-value < 10-13. The prototype R code has been made available as supplementary material [see Additional file 1].

  6. Synthesis of renewable high-density fuel with isophorone.

    PubMed

    Wang, Wei; Liu, Yanting; Li, Ning; Li, Guangyi; Wang, Wentao; Wang, Aiqin; Wang, Xiaodong; Zhang, Tao

    2017-07-21

    1,1,3-Trimethyl-5-(2,4,4-trimethylcyclohexyl)cyclohexane, a renewable high density fuel, was first produced in a high overall carbon yield (~70%) with isophorone which can be derived from hemicellulose. The synthetic route used this work contains three steps. In the first step, 3,3,5-trimethylcyclohexanone was synthesized by the selective hydrogenation of isophorone. Among the investigated catalysts, the Pd/C exhibited the highest activity and selectivity. Over this catalyst, a high carbon yield (99.0%) of 3,3,5-trimethylcyclohexanone was achieved under mild conditions (298 K, 2 MPa H2, 1 h). In the second step, 3,5,5-trimethyl-2-(3,3,5-trimethylcyclohexylidene)cyclohexanone was produced in a high carbon yield (76.4%) by the NaOH catalyzed self-aldol condensation of 3,3,5-trimethylcyclohexanone which was carried out in a round bottom flask attached to the Dean-Stark apparatus. In the third step, the 3,5,5-trimethyl-2-(3,3,5-trimethylcyclohexylidene)cyclohexanone was hydrodeoxygenated under solvent-free conditions. High carbon yield (93.4%) of 1,1,3-trimethyl-5-(2,4,4-trimethylcyclohexyl)cyclohexane was obtained over the Ni/SiO2 catalyst. The 1,1,3-trimethyl-5-(2,4,4-trimethylcyclohexyl)cyclohexane as obtained has a density of 0.858 g mL(-1) and a freezing point of 222.2 K. As a potential application, it can be blended into conventional fuels (such as RP-1, RG-1, etc.) for rocket propulsion.

  7. Effect of obesity on high-density lipoprotein metabolism.

    PubMed

    Rashid, Shirya; Genest, Jacques

    2007-12-01

    Reduced levels of high-density lipoproteins (HDL) in non-obese and obese states are associated with increased risk for the development of coronary artery disease. Therefore, it is imperative to determine the mechanisms responsible for reduced HDL in obese states and, conversely, to examine therapies aimed at increasing HDL levels in these individuals. This paper examines the multiple causes for reduced HDL in obese states and the effect of exercise and diet--two non-pharmacologic therapies--on HDL metabolism in humans. In general, the concentration of HDL-cholesterol is adversely altered in obesity, with HDL-cholesterol levels associated with both the degree and distribution of obesity. More specifically, intra-abdominal visceral fat deposition is an important negative correlate of HDL-cholesterol. The specific subfractions of HDL that are altered in obese states include the HDL2, apolipoprotein A-I, and pre-beta1 subfractions. Decreased HDL levels in obesity have been attributed to both an enhancement in the uptake of HDL2 by adipocytes and an increase in the catabolism of apolipoprotein A-I on HDL particles. In addition, there is a decrease in the conversion of the pre-beta1 subfraction, the initial acceptor of cholesterol from peripheral cells, to pre-beta2 particles. Conversely, as a means of reversing the decrease in HDL levels in obesity, sustained weight loss is an effective method. More specifically, weight loss achieved through exercise is more effective at raising HDL levels than dieting. Exercise mediates positive effects on HDL levels at least partly through changes in enzymes of HDL metabolism. Increased lipid transfer to HDL by lipoprotein lipase and reduced HDL clearance by hepatic triglyceride lipase as a result of endurance training are two important mechanisms for increases in HDL observed from exercise.

  8. High temperature, high density opacity measurements using short pulse lasers

    NASA Astrophysics Data System (ADS)

    Hoarty, D. J.; James, S. F.; Brown, C. R. D.; Williams, B. M.; Guymer, T.; Hill, M.; Morton, J.; Chapman, D.; Shepherd, R.; Dunn, J.; Brown, G.; Schneider, M.; Beiersdorfer, P.; Chung, H. K.; Harris, J. W. O.; Upcraft, L.; Smith, C. C.; Lee, R. W.

    2010-08-01

    Heating of thin foil targets by a high power laser at intensities of 1017 -1019W/cm2 has been studied as a method for producing high temperature, high density samples to investigate X-ray opacity and equation of state. The targets were plastic (parylene N) foils with a buried microdot of a sample material, which was either aluminium, germanium or a mixture of germanium and titanium mixture of germanium and titanium. L-shell and K-shell spectra were taken using crystal spectrometers recording onto film and an ultrafast X-ray streak camera coupled to a conical focussing crystal with a time resolution of 1ps. The conditions in the microdot were inferred by comparing the measured spectra to synthetic spectra produced by the time-dependent collisional-radiative (CR) models FLY and FLYCHK. The data were also compared to simulated spectra from a number of opacity codes assuming local thermodynamic equilibrium (LTE). Temperature and density gradients were taken into account in the comparisons. The sample conditions, inferred from the CR modelling using FLYCHK, were 800±100eV and 1.5±0.5g/cc, in the germanium/titanium samples and 600+50/-150eV, 3-4g/cc in the pure germanium or aluminium samples. The higher densities were achieved by using a combination of long and short pulses to compress and heat the foils respectively. The experimental results and comparisons to predicted spectra are presented and discussed.

  9. Biomimetic High-Density Lipoproteins from a Gold Nanoparticle Template

    NASA Astrophysics Data System (ADS)

    Luthi, Andrea Jane

    For hundreds of years the field of chemistry has looked to nature for inspiration and insight to develop novel solutions for the treatment of human diseases. The ability of chemists to identify, mimic, and modifiy small molecules found in nature has led to the discovery and development of many important therapeutics. Chemistry on the nanoscale has made it possible to mimic natural, macromolecular structures that may also be useful for understanding and treating diseases. One example of such a structure is high-density lipoprotein (HDL). The goal of this work is to use a gold nanoparticle (Au NP) as a template to synthesize functional mimics of HDL and characterize their structure and function. Chapter 1 details the structure and function of natural HDL and how chemistry on the nanoscale provides new strategies for mimicking HDL. This Chapter also describes the first examples of using nanoparticles to mimic HDL. Chapter 2 reports the synthesis and characterization of biomimetic HDL using different sizes of Au NPs and different surface chemistries and how these variables can be used to tailor the properties of biomimetic HDL. From these studies the optimal strategy for synthesizing biomimetic HDL was determined. In Chapter 3, the optimization of the synthesis of biomimetic HDL is discussed as well as a full characterization of its structure. In addition, the work in this chapter shows that biomimetic HDL can be synthesized on a large scale without alterations to its structure or function. Chapter 4 focuses on understanding the pathways by which biomimetic HDL accepts cholesterol from macrophage cells. The results of these studies demonstrate that biomimetic HDL is able to accept cholesterol by both active and passive pathways of cholesterol efflux. In Chapter 5 the preliminary results of in vivo studies to characterize the pharmacokinetics and pharmacodynamics of biomimetic HDL are presented. These studies suggest that biomimetic HDL traffics through tissues prone to

  10. Launch Vehicle with Combustible Polyethylene Case Gasification Chamber Design Basis

    NASA Astrophysics Data System (ADS)

    Yemets, V.

    A single-stage launch vehicle equipped with a combustible tank shell of polyethylene and a moving propulsion plant is proposed. The propulsion plant is composed of a chamber for the gasification of the shell, a compressor of pyrolysed polyethylene and a magnetic powder obturator. It is shown that the “dental” structure of the gasification chamber is necessary to achieve the necessary contact area with the polyethylene shell. This conclusion is drawn from consideration of the thermo- physical properties of polyethylene, calculating quasisteady temperature field in the gasification chamber, estimating gasification rate of polyethylene, launch vehicle shortening rate and area of gasification. Experimental determination of the gasification rate is described. The gasification chamber specific mass as well as the propulsion plant weight-to-thrust ratio are estimated under some assumptions concerning the obturator and compressor. Combustible launch vehicles are compared with conventional launch vehicles taking into consideration their payload mass ratios. Combustible launchers are preferable as small launchers for micro and nano satellites. Reusable versions of such launchers seem suitable if polyethylene tank shells filled with metal or metal hydride fine dusts are used.

  11. Method of fabricating high-density hermetic electrical feedthroughs

    DOEpatents

    Shah, Kedar G.; Pannu, Satinderpall S.; Delima, Terri L.

    2015-06-02

    A method of fabricating electrical feedthroughs selectively removes substrate material from a first side of an electrically conductive substrate (e.g. a bio-compatible metal) to form an array of electrically conductive posts in a substrate cavity. An electrically insulating material (e.g. a bio-compatible sealing glass) is then flowed to fill the substrate cavity and surround each post, and solidified. The solidified insulating material is then exposed from an opposite second side of the substrate so that each post is electrically isolated from each other as well as the bulk substrate. In this manner a hermetic electrically conductive feedthrough construction is formed having an array of electrical feedthroughs extending between the first and second sides of the substrate from which it was formed.

  12. Design of pervaporation membrane for organic-liquid separation based on solubility control by plasma-graft filling polymerization technique

    SciTech Connect

    Yamaguchi, Takeo; Nakao, Shinichi; Kimura, Shoji )

    1993-05-01

    Pervaporation performance through the membranes showed the same tendency as solubility results. The authors have prepared the filling-polymerized membrane for pervaporation of organic-liquid mixtures by the plasma-graft polymerization technique. The membrane is composed of two different polymers: a porous substrate which can suppress membrane swelling and a grafted polymer which forms in the pores of the substrate and exhibits selectivity due to its solubility. The objectives of the present study are to design a suitable membrane for an organic-mixture system by the control of the filling-polymer solubility. Specifically, a porous high-density polyethylene membrane and poly(methylacrylate/acrylamide) copolymer were employed as the porous substrate and grafted polymer, respectively, and grafted copolymer solubility was predicted by Hansen solubility parameters (HSP). The grafted polymer composition and its solubility behavior could be controlled by varying the monomer composition, and the solubility change was in accordance with the prediction by HSP. Pervaporation performance through the membranes showed the same tendency as solubility results. The authors concluded that an optimum pervaporation membrane can be designed on the basis of solubility control through use of these techniques for polymerization and prediction.

  13. Fuel-rich catalytic combustion of a high density fuel

    NASA Technical Reports Server (NTRS)

    Brabbs, Theodore A.; Merritt, Sylvia A.

    1993-01-01

    Fuel-rich catalytic combustion (ER is greater than 4) of the high density fuel exo-tetrahydrocyclopentadiene (JP-10) was studied over the equivalence ratio range 5.0 to 7.6, which yielded combustion temperatures of 1220 to 1120 K. The process produced soot-free gaseous products similar to those obtained with iso-octane and jet-A in previous studies. The measured combustion temperature agreed well with that calculated assuming soot was not a combustion product. The process raised the effective hydrogen/carbon (H/C) ratio from 1.6 to over 2.0, thus significantly improving the combustion properties of the fuel. At an equivalence ratio near 5.0, about 80 percent of the initial fuel carbon was in light gaseous products and about 20 percent in larger condensable molecules. Fuel-rich catalytic combustion has now been studied for three fuels with H/C ratios of 2.25 (iso-octane), 1.92 (jet-A), and 1.6 (JP-10). A comparison of the product distribution of these fuels shows that, in general, the measured concentrations of the combustion products were monotonic functions of the H/C ratio with the exception of hydrogen and ethylene. In these cases, data for JP-10 fell between iso-octane and jet-A rather than beyond jet-A. It is suggested that the ring cross-linking structure of JP-10 may be responsible for this behavior. All the fuels studied showed that the largest amounts of small hydrocarbon molecules and the smallest amounts of large condensable molecules occurred at the lower equivalence ratios. This corresponds to the highest combustion temperatures used in these studies. Although higher temperatures may improve this mix, the temperature is limited. First, the life of the present catalyst would be greatly shortened when operated at temperatures of 1300 K or greater. Second, fuel-rich catalytic combustion does not produce soot because the combustion temperatures used in the experiments were well below the threshold temperature (1350 K) for the formation of soot. Increasing

  14. Constraining cloud parameters using high density gas tracers in galaxies

    NASA Astrophysics Data System (ADS)

    Kazandjian, M. V.; Pelupessy, I.; Meijerink, R.; Israel, F. P.; Coppola, C. M.; Rosenberg, M. J. F.; Spaans, M.

    2016-11-01

    Far-infrared molecular emission is an important tool used to understand the excitation mechanisms of the gas in the interstellar medium (ISM) of star-forming galaxies. In the present work, we model the emission from rotational transitions with critical densities n ≳ 104 cm-3. We include 4-3 < J ≤ 15-14 transitions of CO and 13CO , in addition to J ≤ 7-6 transitions of HCN, HNC, and HCO+ on galactic scales. We do this by re-sampling high density gas in a hydrodynamic model of a gas-rich disk galaxy, assuming that the density field of the ISM of the model galaxy follows the probability density function (PDF) inferred from the resolved low density scales. We find that in a narrow gas density PDF, with a mean density of 10 cm-3 and a dispersion σ = 2.1 in the log of the density, most of the emission of molecular lines, even of gas with critical densities >104 cm-3, emanates from the 10-1000 cm-3 part of the PDF. We construct synthetic emission maps for the central 2 kpc of the galaxy and fit the line ratios of CO and 13CO up to J = 15-14, as well as HCN, HNC, and HCO+ up to J = 7-6, using one photo-dissociation region (PDR) model. We attribute the goodness of the one component fits for our model galaxy to the fact that the distribution of the luminosity, as a function of density, is peaked at gas densities between 10 and 1000 cm-3, with negligible contribution from denser gas. Specifically, the Mach number, ℳ, of the model galaxy is 10. We explore the impact of different log-normal density PDFs on the distribution of the line-luminosity as a function of density, and we show that it is necessary to have a broad dispersion, corresponding to Mach numbers ≳30 in order to obtain significant (>10%) emission from n> 104 cm-3 gas. Such Mach numbers are expected in star-forming galaxies, luminous infrared galaxies (LIRGS), and ultra-luminous infrared galaxies (ULIRGS). This method provides a way to constrain the global PDF of the ISM of galaxies from observations of

  15. High-Density Plasma Reactors: Simulations for Design

    NASA Technical Reports Server (NTRS)

    Hash, David B.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1998-01-01

    The development of improved and more efficient plasma reactors is a costly process for the semiconductor industry. Until five years ago, the Industry made most of its advancements through a trial and error approach. More recently, the role of computational modeling in the design process has increased. Both conventional computational fluid dynamics (CFD) techniques like Navier-Stokes solvers as well as particle simulation methods are used to model plasma reactor flowfields. However, since high-density plasma reactors generally operate at low gas pressures on the order of 1 to 10 mTorr, a particle simulation may be necessary because of the failure of CFD techniques to model rarefaction effects. The direct simulation Monte Carlo method is the most widely accepted and employed particle simulation tool and has previously been used to investigate plasma reactor flowfields. A plasma DSMC code is currently under development at NASA Ames Research Center with its foundation as the object-oriented parallel Cornell DSMC code, MONACO. The present investigation is a follow up of a neutral flow investigation of the effects of process parameters as well as reactor design on etch rate and etch rate uniformity. The previous work concentrated on silicon etch of a chlorine flow in a configuration typical of electron cyclotron resonance (ECR) or helical resonator type reactors. The effects of the plasma on the dissociation chemistry were modeled by making assumptions about the electron temperature and number density. The electrons or ions themselves were not simulated.The present work extends these results by simulating the charged species.The electromagnetic fields are calculated such that power deposition is modeled self-consistently. Electron impact reactions are modeled along with mechanisms for charge exchange. An bipolar diffusion assumption is made whereby electrons remain tied to the ions. However, the velocities of tile electrons are allowed to be modified during collisions

  16. Triglyceride, high density lipoprotein, and coronary heart disease.

    PubMed

    The National Institutes of Health Consensus Development Conference on Triglyceride, High Density Lipoprotein, and Coronary Heart Disease brought together experts in lipid metabolism, epidemiologists, and clinicians as well as other health care professionals and the public to address the following questions: (1) is the relationship of high triglyceride and/or low HDL cholesterol with coronary heart disease causal? (2) Will reduction of high triglyceride and/or elevation of HDL cholesterol help prevent coronary heart disease? (3) Under what circumstances should triglycerides and HDL cholesterol be measured? (4) Under what circumstances should active intervention to lower triglyceride and/or raise HDL cholesterol be considered in high risk individuals and the general population? (5) What can be accomplished by dietary, other hygienic, and drug treatments? (6) What are the significant questions for future research? Following two days of presentations by experts and discussion by the audience, a consensus panel weighed the evidence and prepared their consensus statement. Among their findings, the panel concluded that (1) existing data provide considerable support for a causal relationship between low HDL and CHD; however, with respect to TG data are mixed and the evidence on a causal relationship is incomplete; (2) initial TG and/or HDL levels modify benefit achieved by lowering low density lipoprotein cholesterol (LDL-C); however, evidence from clinical trials is insufficient to draw conclusions about specific benefits of TG and/or HDL altering therapy; (3) HDL-C measurement should be added to total cholesterol measurement when evaluating CHD risk in healthy individuals provided accuracy of measurement, appropriate counseling, and followup can be assured; (4) there is general agreement with the Adult Treatment Panel (ATP) guidelines that LDL-C is essential in cardiovascular risk assessment, as well as that persons with elevations of LDL-C greater than 150 mg

  17. High-Density, High-Bandwidth, Multilevel Holographic Memory

    NASA Technical Reports Server (NTRS)

    Chao, Tien-Hsin

    2008-01-01

    A proposed holographic memory system would be capable of storing data at unprecedentedly high density, and its data transfer performance in both reading and writing would be characterized by exceptionally high bandwidth. The capabilities of the proposed system would greatly exceed even those of a state-of-the art memory system, based on binary holograms (in which each pixel value represents 0 or 1), that can hold .1 terabyte of data and can support a reading or writing rate as high as 1 Gb/s. The storage capacity of the state-of-theart system cannot be increased without also increasing the volume and mass of the system. However, in principle, the storage capacity could be increased greatly, without significantly increasing the volume and mass, if multilevel holograms were used instead of binary holograms. For example, a 3-bit (8-level) hologram could store 8 terabytes, or an 8-bit (256-level) hologram could store 256 terabytes, in a system having little or no more size and mass than does the state-of-the-art 1-terabyte binary holographic memory. The proposed system would utilize multilevel holograms. The system would include lasers, imaging lenses and other beam-forming optics, a block photorefractive crystal wherein the holograms would be formed, and two multilevel spatial light modulators in the form of commercially available deformable-mirror-device spatial light modulators (DMDSLMs) made for use in high speed input conversion of data up to 12 bits. For readout, the system would also include two arrays of complementary metal oxide/semiconductor (CMOS) photodetectors matching the spatial light modulators. The system would further include a reference-beam sterring device (equivalent of a scanning mirror), containing no sliding parts, that could be either a liquid-crystal phased-array device or a microscopic mirror actuated by a high-speed microelectromechanical system. Time-multiplexing and the multilevel nature of the DMDSLM would be exploited to enable writing

  18. Fuel-rich catalytic combustion of a high density fuel

    SciTech Connect

    Brabbs, T.A.; Merritt, S.A.

    1993-07-01

    Fuel-rich catalytic combustion (ER is greater than 4) of the high density fuel exo-tetrahydrocyclopentadiene (JP-10) was studied over the equivalence ratio range 5.0 to 7.6, which yielded combustion temperatures of 1220 to 1120 K. The process produced soot-free gaseous products similar to those obtained with iso-octane and jet-A in previous studies. The measured combustion temperature agreed well with that calculated assuming soot was not a combustion product. The process raised the effective hydrogen/carbon (H/C) ratio from 1.6 to over 2.0, thus significantly improving the combustion properties of the fuel. At an equivalence ratio near 5.0, about 80 percent of the initial fuel carbon was in light gaseous products and about 20 percent in larger condensable molecules. Fuel-rich catalytic combustion has now been studied for three fuels with H/C ratios of 2.25 (iso-octane), 1.92 (jet-A), and 1.6 (JP-10). A comparison of the product distribution of these fuels shows that, in general, the measured concentrations of the combustion products were monotonic functions of the H/C ratio with the exception of hydrogen and ethylene. In these cases, data for JP-10 fell between iso-octane and jet-A rather than beyond jet-A. It is suggested that the ring cross-linking structure of JP-10 may be responsible for this behavior. All the fuels studied showed that the largest amounts of small hydrocarbon molecules and the smallest amounts of large condensable molecules occurred at the lower equivalence ratios. This corresponds to the highest combustion temperatures used in these studies. Although higher temperatures may improve this mix, the temperature is limited. First, the life of the present catalyst would be greatly shortened when operated at temperatures of 1300 K or greater. Second, fuel-rich catalytic combustion does not produce soot because the combustion temperatures used in the experiments were well below the threshold temperature (1350 K) for the formation of soot.

  19. Effect of drugs on high-density lipoprotein.

    PubMed

    McKenney, James M

    2007-03-01

    The National Cholesterol Education Program Adult Treatment Panel III found evidence for raising high-density lipoprotein cholesterol (HDL-C) to reduce coronary artery disease (CAD) events supports use of HDL-C to help modify low-density lipoprotein cholesterol (LDL-C)-lowering goals, but not to establish new HDL-C-focused treatment recommendations. However, the HDL-C-raising clinical trials provide important lessons to help guide clinical management of dyslipidemic patients. The fibrate outcome trials demonstrate that these drugs reduce CAD events, but not death. Their greatest benefit is in patients with atherogenic dyslipidemia characterized by high triglycerides, small LDL particles, and low HDL-C. Unfortunately, there is no information on whether these drugs extend risk reduction when added to a statin. The niacin outcome trials also demonstrate a reduction in CAD events, both with niacin monotherapy and in combination with a statin. Unfortunately, most of the trials are too small to address the impact of niacin on mortality. In the clinic, statins are most useful for their LDL-C-lowering efficacy, although their modest HDL-C-raising effects can be important in CAD risk reduction. In most cases, other therapies will need to be added to a statin to augment HDL-C-raising, and the most effective drug for achieving this is niacin. The greatest challenge with the use of niacin is managing the vasodilatory side effects, but this can be effectively done in the majority of patients. Fibrates can also be added to a statin for management of atherogenic dyslipidemia. These drugs are among the most effective triglyceride-lowering drugs, and they also increase HDL-C levels, but not as much as niacin. The biggest concern with combining a fibrate with a statin is the enhanced risk of severe muscle toxicity, but this appears to be a problem unique to gemfibrozil, and not fenofibrate. In the research center, new approaches are under development for enhancing the availability of

  20. Comparison of high-density carbon implosions in unlined uranium versus gold hohlraums

    NASA Astrophysics Data System (ADS)

    Dewald, Eduard; Meezan, Nathan; Tommasini, Riccardo; Khan, Shahab; MacKinnon, Andrew; Berzak Hopkins, Laura; Divol, Laurent; Lepape, Sebastien; Moore, Alastair; Schneider, Marilyn; Pak, Arthur; Nikroo, Abbas; Landen, Otto

    2016-10-01

    In Inertial Confinement Fusion (ICF) implosions, laser energy is converted to x-ray radiation in hohlraums with High-Z walls. At radiation temperatures near 300 eV relevant for ICF experiments, the radiative losses in heating the wall are lower for U than for Au hohlraums. Furthermore, the intensity of the ``M-band'' x-rays with photon energies h ν >1.8 keV is lower for uranium, allowing for reduced capsule dopant concentrations employed to minimize inner ablator preheat and hence keep favorable fuel/ablator interface Atwood numbers. This in turn improves the ablator rocket efficiency and reduces the risk of polluting the hot-spot with emissive dopant material. The first uranium vacuum hohlraum experiments on the National Ignition Facility (NIF) with undoped high-density carbon (HDC, or diamond) capsules have demonstrated 30% lower ``M-band'' intensity relative to Au, resulting in lower inflight ablator thickness due to reduced preheat. In addition, fusion neutron yields are 2x higher in U than in Au hohlraums for D2-gas filled capsule implosions at ICF relevant velocities of 380 +/-20 km/s. These results have led the NIF ICF implosions to routinely employ U hohlraums. Prepared by LLNL under Contract DE-AC52-07NA27344.

  1. Executive Dysfunction and Reward Dysregulation: A High-Density Electrical Mapping Study in Cocaine Abusers

    PubMed Central

    Morie, Kristen P.; De Sanctis, Pierfilippo; Garavan, Hugh; Foxe, John J.

    2015-01-01

    Executive function deficits and reward dysregulation, which mainly manifests as anhedonia, are well documented in drug abusers. We investigated specific aspects of executive function (inhibitory control and cognitive control), as well as anhedonia, in a cohort of current cocaine abusers in order to ascertain to what extent these factors are associated with more severe drug dependence. Participants filled out questionnaires relating to anhedonia and their addiction history. Participants also performed a response inhibition task while high-density event-related potentials (ERPs) were recorded. Electrophysiological responses to successful inhibitions (N2/P3 components) and to commission errors (ERN/Pe components) were compared between 23 current users of cocaine and 27 non-using controls. A regression model was performed to determine the association of our measures of reward dysregulation and executive function with addiction severity. As expected, cocaine users performed more poorly than controls on the inhibitory control task and showed significant electrophysiological differences. They were also generally more anhedonic than controls. Higher levels of anhedonia were associated with more severe substance use, whereas the level of executive dysfunction was not associated with more severe substance use. However, N2 amplitude was associated with duration of drug use. Further, inhibitory control and anhedonia were correlated, but only in controls. These data suggest that while executive dysfunction characterizes drug abuse, it is anhedonia, independent of executive dysfunction, that is most strongly associated with more severe use. PMID:24911989

  2. Effects of acute exercise on high density lipoprotein cholesterol and high density lipoprotein subfractions in moderately trained females

    PubMed Central

    Gordon, P. M.; Fowler, S.; Warty, V.; Danduran, M.; Visich, P.; Keteyian, S.

    1998-01-01

    Increases in high density lipoprotein cholesterol (HDL-C) levels have previously been reported after moderate exercise bouts lasting less than two hours in men. Little information exists, however, on HDL-C responses after moderate duration exercise in women. Post-exercise HDL- C modifications may appear differently in women because of higher baseline HDL-C concentrations and differences in lipolytic activity. To determine the influence of exercise on acute HDL-C responses in women, 12 trained premenopausal women (22 (4) years old; mean (SD)) who ran 24- 48 km a week exercised on a motor driven treadmill at 75% VO2MAX until 3.34 MJ (800 kcal) were expended (72 (9) min). Subjects were all tested during the early follicular phase of their menstrual cycle. Fasting blood samples were obtained before exercise (baseline), immediately after (IPE), one hour after (1 h PE), 24 hours after (24 h PE), and 48 hours after (48 h PE) exercise. Plasma was analysed for HDL-C, HDL2-C, and HDL3-C. A significant increase in HDL-C was observed 48 h PE (p<0.05). HDL3-C increased IPE (p<0.01) but returned to baseline at 1 h PE. In contrast, HDL2-C was not significantly different from baseline at any time point. The rise in HDL-C, however, was attributed to an increase in both HDL2 and HDL3. Moreover, at 48 h PE, the increase in HDL-C correlated highly with changes in HDL2-C (r = 0.92). Thus it appears that exercise of moderate duration can elicit similar post- exercise increases in HDL-C in women to those previously reported in men. However, the changes in HDL subfractions leading to the rise in HDL-C may be different in women. 


 PMID:9562167

  3. Attenuation of heavy metals by geosynthetics in the coal gangue-filled columns.

    PubMed

    Wang, Ping; Hu, Zhenqi; Wang, Peijun

    2013-01-01

    In the subsided areas backfilled with coal gangue, an issue of continuing environmental concern is the migration of hazardous metals to the subsurface soil and groundwater. As an effective isolation material, geosynthetics have been scarcely applied into mining areas reclamation of China. This paper describes research aimed at characterizing the behaviours of different geosynthetics in the leaching columns filled with coal gangues. Four types of geosynthetics were selected: fibres needle-punched nonwoven geotextiles, high-density polyethylene, needle-punched Na-bentonite geosynthetic clay liner (GCL-NP) and Na-bentonite geosynthetic-overbited film. Heavy metals were significantly attenuated and by monitoring aqueous solutions in the whole percolation period, negative correlation was found between pH value and concentration of heavy metals. Generally, GCL-NP showed comparatively better effects on attenuating the migration of heavy metals. According to the meta-analysis of heavy metals present in the leachates and retained in the columns, geosynthetics have good capabilities of sorption and retardation, which can delay the breakthrough time of heavy metals and retard the accumulation in the subsurface. Future research will use X-ray diffraction and micro-imaging (electron microprobe and scanning electron microscopy) to further explain retention mechanisms.

  4. Effect of gamma irradiation on mechanical, thermal and rheological behavior of HDPE filled with seaweed residues

    NASA Astrophysics Data System (ADS)

    Cataño, L.; Albano, C.; Karam, A.; Domínguez, N.; Sánchez, Y.; González, J.

    2005-07-01

    The present work shows the results obtained during the investigation of the influence of gamma irradiation on mechanical, thermal and rheological properties of high-density polyethylene (HDPE) filled with seaweed residues (SR). The SR used was located on Venezuelan coastlines and they are composed mainly by CaCO3 in aragonite phase. The HDPE was extruded along with the filler at different compositions (20, 30 and 40 wt.%). The composites were exposed to a 60Co source irradiated at 25 and 100 kGy. From the obtained results, it was noticed that Young modulus remained constant with filler content. Moreover, the influence of filler content was found to be more prominent on properties like tensile stress and elongation at break. On the other hand, thermal analysis showed that filler content had no significant influence on thermal stability. Still, it is necessary to point out that low radiation doses improved thermal stability of the composites. From rheological studies it was observed a decreasing of melt flow index (MFI) by increasing the SR amount and radiation. Therefore, was determinate that high filler content composites are the best choice to be considered for biomedical and industrial applications.

  5. Characterization of green rHDPE biocomposites filled with natural filler: Rheological and thermal studies

    NASA Astrophysics Data System (ADS)

    Lim, B. Y.; Voon, C. H.; Adawiah Mahmod, R.

    2016-11-01

    Palm kernel shell filled recycled high density polyethylene (rHDPE/PKS) biocomposites were produced in order to reduce the waste product from palm oil production. The biocomposites at various filler loading were prepared by melt mixing at 180 °C. Ultra Plast TP0' was selected as coupling agent in rHDPE/PKS biocomposites, in order to modify the properties of biocomposites. It was found that the higher filler loading had reduced the melt flow index (MFI) values. However, with the increasing of testing temperature from 180 to 210 °C, the MFI values of the biocomposites were increased. The presence of Ultra Plast TP01was capable to increase MFI values of the biocomposites. The thermal studies showed that thermal stability of the biocomposites was affected by PKS loading and coupling agent. Though the thermal stability of biocomposites was reduced by PKS, it can be improved by Ultra Plast TP01. Hence, Ultra Plast TP01 can serve as an effective coupling agent for rHDPE/PKS.

  6. Developing High-Density Diffuse Optical Tomography for Neuroimaging

    NASA Astrophysics Data System (ADS)

    White, Brian Richard

    Clinicians who care for brain-injured patients and premature infants desire a bedside monitor of brain function. A decade ago, there was hope that optical imaging would be able to fill this role, as it combined fMRI's ability to construct cortical maps with EEG's portable, cap-based systems. However, early optical systems had poor imaging performance, and the momentum for the technique slowed. In our lab, we develop diffuse optical tomography (DOT), which is a more advanced method of performing optical imaging. My research has been to pioneer the in vivo use of DOT for advanced neuroimaging by (1) quantifying the advantages of DOT through both in silico simulation and in vivo performance metrics, (2) restoring confidence in the technique with the first retinotopic mapping of the visual cortex (a benchmark for fMRI and PET), and (3) creating concepts and methods for the clinical translation of DOT. Hospitalized patients are unable to perform complicated neurological tasks, which has motivated us to develop the first DOT methods for resting-state brain mapping with functional connectivity. Finally, in collaboration with neonatologists, I have extended these methods with proof-of-principle imaging of brain-injured premature infants. This work establishes DOT's improvements in imaging performance and readies it for multiple clinical and research roles.

  7. Getting a prescription filled

    MedlinePlus

    ... are located inside of a grocery or large "chain" store. It is best to fill all prescriptions ... be used for long-term medicines and medical supplies. The website should have clear directions for filling ...

  8. Catalytic Hydroxylation of Polyethylenes

    PubMed Central

    2017-01-01

    Polyolefins account for 60% of global plastic consumption, but many potential applications of polyolefins require that their properties, such as compatibility with polar polymers, adhesion, gas permeability, and surface wetting, be improved. A strategy to overcome these deficiencies would involve the introduction of polar functionalities onto the polymer chain. Here, we describe the Ni-catalyzed hydroxylation of polyethylenes (LDPE, HDPE, and LLDPE) in the presence of mCPBA as an oxidant. Studies with cycloalkanes and pure, long-chain alkanes were conducted to assess precisely the selectivity of the reaction and the degree to which potential C–C bond cleavage of a radical intermediate occurs. Among the nickel catalysts we tested, [Ni(Me4Phen)3](BPh4)2 (Me4Phen = 3,4,7,8,-tetramethyl-1,10-phenanthroline) reacted with the highest turnover number (TON) for hydroxylation of cyclohexane and the highest selectivity for the formation of cyclohexanol over cyclohexanone (TON, 5560; cyclohexanol/(cyclohexanone + ε-caprolactone) ratio, 10.5). The oxidation of n-octadecane occurred at the secondary C–H bonds with 15.5:1 selectivity for formation of an alcohol over a ketone and 660 TON. Consistent with these data, the hydroxylation of various polyethylene materials by the combination of [Ni(Me4Phen)3](BPh4)2 and mCPBA led to the introduction of 2.0 to 5.5 functional groups (alcohol, ketone, alkyl chloride) per 100 monomer units with up to 88% selectivity for formation of alcohols over ketones or chloride. In contrast to more classical radical functionalizations of polyethylene, this catalytic process occurred without significant modification of the molecular weight of the polymer that would result from chain cleavage or cross-linking. Thus, the resulting materials are new compositions in which hydroxyl groups are located along the main chain of commercial, high molecular weight LDPE, HDPE, and LLDPE materials. These hydroxylated polyethylenes have improved wetting

  9. Polyethylene Glycol Propionaldehydes

    NASA Technical Reports Server (NTRS)

    Harris, Joe M.; Sedaghat-Herati, Mohammad R.; Karr, Laurel J.

    1992-01-01

    New class of compounds derived from polyethylene glycol (PEG's) namely, PEG-propionaldehydes, offers two important advantages over other classes of PEG aldehyde derivatives: compounds exhibit selective chemical reactivity toward amino groups and are stable in aqueous environment. PEG's and derivatives used to couple variety of other molecules, such as, to tether protein molecules to surfaces. Biotechnical and biomedical applications include partitioning of two phases in aqueous media; immobilization of such proteins as enzymes, antibodies, and antigens; modification of drugs; and preparation of protein-rejecting surfaces. In addition, surfaces coated with PEG's and derivatives used to control wetting and electroosmosis. Another potential application, coupling to aminated surfaces.

  10. A Lagrangian-Eulerian Approach to Modeling Homogeneous Condensation in High Density Flows (POSTPRINT)

    DTIC Science & Technology

    2011-01-01

    Homogeneous Condensation in High Density Gas Expansions (Postprint) 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Ryan Jansen ...Prescribed by ANSI Std. 239.18 A Lagrangian–Eulerian approach to modeling homogeneous condensation in high density gas expansions Ryan Jansen , Natalia...Lagrangian–Eulerian approach to modeling homogeneous condensation in high density gas expansions Ryan Jansen ,1 Natalia Gimelshein,2 Sergey Gimelshein,2

  11. 76 FR 58393 - High Density Traffic Airports; Notice of Determination Regarding Low Demand Periods at Ronald...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-09-21

    ... INFORMATION CONTACT: Robert Hawks, Office of the Chief Counsel, Federal Aviation Administration, 800...-mail: rob.hawks@faa.gov . SUPPLEMENTARY INFORMATION: Background The FAA issued the High Density...

  12. [Growth of microfungi on the external polyethylene anticorrosive coating of oil-gas pipes].

    PubMed

    Subbota, A G; Chuenko, A I; Ostapiuk, S N

    2014-01-01

    The authors have studied the resistance of external anticorrosive polyethylene coat of oil-gas pipes (based on the high-density polyethylene, HDPE) to the action of microfungi, natural contamination, fungistatic and fungicide activity. It was found that the intensity of growth of standard test cultures on the surface of polyethylene coat increases in terms which imitate mineral and organic contaminations, and this results in the decrease of the index of its resistance to the action of microfungi. The microfungi, found in the process of study of natural contamination of polyethylene coat and its components, are presented by six species, Alternaria sp. most frequently occurring among them. The presence of admixtures of nitrogenic and phosphoric organic substances in chemical composition of control standards of adhesive and HDPE, which were not exposed to the influence of microfungi, was established by the method of IR spectroscopy. Changes of the IR spectra were noticed in the surface layer of high density polyethylene pellets under the influence of Penicillium funiculosum 171703 that evidences for the process of its slow oxidation. It is assumed that the damaging of the coating components is due to the presence in their chemical composition of impurities of nitrogen- and phosphorus-containing compounds that are easily absorbed by microscopic fungi.

  13. Polyethylene cellulose nanofibrils nanocomposites.

    PubMed

    Maia, Thiago Henrique Silveira; Larocca, Nelson Marcos; Beatrice, Cesar Augusto Gonçalves; de Menezes, Aparecido Júnior; de Freitas Siqueira, Gilberto; Pessan, Luiz Antonio; Dufresne, Alain; França, Marcos Pini; de Almeida Lucas, Alessandra

    2017-10-01

    This paper investigates the use of an aqueous dispersion of polyethylene copolymer with a relatively high content of acrylic acid as a compatibilizer and as an alternative medium to obtain polyethylene CNF nanocomposites. The CNF content was varied from 1 to 90wt% and the appearance, optical, thermal, mechanical and rheological properties, as well the morphology of the films were evaluated. The PE/CNF films are transparent up to 20wt% of NFC indicating a good dispersion of CNF, but a poor distribution, with PE-rich and CNF-rich regions observed by SEM. Improved mechanical properties were achieved, with a 100% and 15,900% increase in the Young's modulus with 1wt% and 90wt% NFC, respectively. The rheological behavior indicated good melt processability. According to these results, aqueous polyolefin dispersions seem to be a promising, easy and relatively fast route for obtaining cellulose/polyolefins nanocomposites with low to high contents of cellulose nanofibrils. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. High-density grids for efficient data collection from multiple crystals

    PubMed Central

    Baxter, Elizabeth L.; Aguila, Laura; Alonso-Mori, Roberto; Barnes, Christopher O.; Bonagura, Christopher A.; Brehmer, Winnie; Brunger, Axel T.; Calero, Guillermo; Caradoc-Davies, Tom T.; Chatterjee, Ruchira; Degrado, William F.; Fraser, James S.; Ibrahim, Mohamed; Kern, Jan; Kobilka, Brian K.; Kruse, Andrew C.; Larsson, Karl M.; Lemke, Heinrik T.; Lyubimov, Artem Y.; Manglik, Aashish; McPhillips, Scott E.; Norgren, Erik; Pang, Siew S.; Soltis, S. M.; Song, Jinhu; Thomaston, Jessica; Tsai, Yingssu; Weis, William I.; Woldeyes, Rahel A.; Yachandra, Vittal; Yano, Junko; Zouni, Athina; Cohen, Aina E.

    2016-01-01

    Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassette or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into the Blu-Ice/DCSS experimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. Crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures. PMID:26894529

  15. High-density grids for efficient data collection from multiple crystals

    SciTech Connect

    Baxter, Elizabeth L.; Aguila, Laura; Alonso-Mori, Roberto; Barnes, Christopher O.; Bonagura, Christopher A.; Brehmer, Winnie; Brunger, Axel T.; Calero, Guillermo; Caradoc-Davies, Tom T.; Chatterjee, Ruchira; Degrado, William F.; Fraser, James S.; Ibrahim, Mohamed; Kern, Jan; Kobilka, Brian K.; Kruse, Andrew C.; Larsson, Karl M.; Lemke, Heinrik T.; Lyubimov, Artem Y.; Manglik, Aashish; McPhillips, Scott E.; Norgren, Erik; Pang, Siew S.; Soltis, S. M.; Song, Jinhu; Thomaston, Jessica; Tsai, Yingssu; Weis, William I.; Woldeyes, Rahel A.; Yachandra, Vittal; Yano, Junko; Zouni, Athina; Cohen, Aina E.

    2016-01-01

    Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassette or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into theBlu-Ice/DCSSexperimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. Crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures.

  16. Fabrication, Micro-structural Analysis, and Mechanical Testing of High Density Polymeric Foam

    NASA Astrophysics Data System (ADS)

    Marks, Trevor Gustov

    Foams, or what are often called cellular solids, are some of the most widely used materials in the modern era. In general, foam is a porous substance formed by the introduction of gas filled pores into condensed matter; the result is typically a light weight substance with properties related to the base (non-porous) medium. Applications of foams include: vibration dampening, energy mitigation (such as packaging and bike helmets), insulation, filtration, and flotation. The focus of this work is on the properties of flexible elastomeric foam of high relative-density. The bulk of existing literature on elastomeric foam is concerned with foam of low relative-density (ratio of the foam density to the density of the material from which the foam is formed ≤ 0.1). The relationship between the micro-structure of high relative-density foam and its mechanical response has, in large part, not been subjected to systematic investigation heretofore. The present work examines how the micro-structural features of pore shape, size, and location affect the macro-structural response of relative high density foam to compressive loading. In order to carry out this study, methods were developed and employed to control a foam's micro-structure, and hence its mechanical response, with the use of temporary pore forming particles and micron scale inclusions. Advanced microscopy techniques were used to observe, in situ, the evolution of a foam's micro-structure under compressive loading, and the results were correlated with the evolution of the foam's stress - strain response. Additionally, quantitative methods were developed and employed to describe numerically the foam's micro-structural features, such as: (i), pore shape, (ii), pore size, and (iii), the arrangement of the pores with respect to each other. Numerous foams were produced, tested, and subjected to the

  17. High-density grids for efficient data collection from multiple crystals

    DOE PAGES

    Baxter, Elizabeth L.; Aguila, Laura; Alonso-Mori, Roberto; ...

    2015-11-03

    Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassettemore » or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into theBlu-Ice/DCSSexperimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. As a result, crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures.« less

  18. High-density grids for efficient data collection from multiple crystals

    SciTech Connect

    Baxter, Elizabeth L.; Aguila, Laura; Alonso-Mori, Roberto; Barnes, Christopher O.; Bonagura, Christopher A.; Brehmer, Winnie; Brunger, Axel T.; Calero, Guillermo; Caradoc-Davies, Tom T.; Chatterjee, Ruchira; Degrado, William F.; Fraser, James S.; Ibrahim, Mohamed; Kern, Jan; Kobilka, Brian K.; Kruse, Andrew C.; Larsson, Karl M.; Lemke, Heinrik T.; Lyubimov, Artem Y.; Manglik, Aashish; McPhillips, Scott E.; Norgren, Erik; Pang, Siew S.; Soltis, S. M.; Song, Jinhu; Thomaston, Jessica; Tsai, Yingssu; Weis, William I.; Woldeyes, Rahel A.; Yachandra, Vittal; Yano, Junko; Zouni, Athina; Cohen, Aina E.

    2015-11-03

    Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassette or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into theBlu-Ice/DCSSexperimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. As a result, crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures.

  19. High-density grids for efficient data collection from multiple crystals

    SciTech Connect

    Baxter, Elizabeth L.; Aguila, Laura; Alonso-Mori, Roberto; Barnes, Christopher O.; Bonagura, Christopher A.; Brehmer, Winnie; Brunger, Axel T.; Calero, Guillermo; Caradoc-Davies, Tom T.; Chatterjee, Ruchira; Degrado, William F.; Fraser, James S.; Ibrahim, Mohamed; Kern, Jan; Kobilka, Brian K.; Kruse, Andrew C.; Larsson, Karl M.; Lemke, Heinrik T.; Lyubimov, Artem Y.; Manglik, Aashish; McPhillips, Scott E.; Norgren, Erik; Pang, Siew S.; Soltis, S. M.; Song, Jinhu; Thomaston, Jessica; Tsai, Yingssu; Weis, William I.; Woldeyes, Rahel A.; Yachandra, Vittal; Yano, Junko; Zouni, Athina; Cohen, Aina E.

    2016-01-01

    Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassette or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into theBlu-Ice/DCSSexperimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. Crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures.

  20. High-density grids for efficient data collection from multiple crystals.

    PubMed

    Baxter, Elizabeth L; Aguila, Laura; Alonso-Mori, Roberto; Barnes, Christopher O; Bonagura, Christopher A; Brehmer, Winnie; Brunger, Axel T; Calero, Guillermo; Caradoc-Davies, Tom T; Chatterjee, Ruchira; Degrado, William F; Fraser, James S; Ibrahim, Mohamed; Kern, Jan; Kobilka, Brian K; Kruse, Andrew C; Larsson, Karl M; Lemke, Heinrik T; Lyubimov, Artem Y; Manglik, Aashish; McPhillips, Scott E; Norgren, Erik; Pang, Siew S; Soltis, S M; Song, Jinhu; Thomaston, Jessica; Tsai, Yingssu; Weis, William I; Woldeyes, Rahel A; Yachandra, Vittal; Yano, Junko; Zouni, Athina; Cohen, Aina E

    2016-01-01

    Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassette or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into the Blu-Ice/DCSS experimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. Crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures.

  1. On-chip high density droplet-on-template (DOT) array

    NASA Astrophysics Data System (ADS)

    Kim, Jitae; Song, Simon

    2015-01-01

    In this report, we present a new method for generating a high-density (2D) droplet array using double-layered polydimethylsiloxane (PDMS) templates containing honeycomb microwells. Without external flow control, a droplet-on-template (DOT) was created by utilizing capillary forces associated with the interfacial tension between the aqueous and oil phases. The DOT process involved three simple steps: (1) vacuum-assisted filling of microwells; (2) excess water removal; and (3) covering the droplet array with oil. To demonstrate the concept of the DOT, we generated spherical water droplets 147, 191, 238, 326 and 405 μm in diameter from corresponding microwells with lengths of 200, 300, 400, 600 and 800 μm, respectively and a height of 76 μm (up to ~10,000 droplets on a template 25  ×  25 mm). Two important factors, including the aspect ratio (height-to-length ratio) of the microwell and the interfacial tension of the two phases, were investigated to understand how those factors affect the shape of the droplets (‘sphere’ or ‘dome’). All the droplets were spherical up to an aspect ratio of 0.55. The droplets were dome-shaped for aspect ratios above 0.82. For a 1 mM sodium dodecyl sulfate (SDS) solution, the use of mineral oil (which had the highest interfacial tension studied) produced spherical droplets, but dome-shaped droplets were produced by corn oil and oleic acid.

  2. Fitness, Heart Disease, and High-Density Lipoproteins: A Look at the Relationships.

    ERIC Educational Resources Information Center

    McCunney, Robert J.

    1987-01-01

    The role of fitness in preventing coronary heart disease is explored. Research on high-density lipoprotein, which has been found to be one of the most critical determinants of risk, is reviewed. The relationship between fitness, high-density lipoprotein, and coronary heart disease is assessed, and clinical implications are spelled out. (MT)

  3. Renewable high-density spiro-fuels from lignocellulose-derived cyclic ketones.

    PubMed

    Xie, Junjian; Zhang, Xiangwen; Pan, Lun; Nie, Genkuo; E, Xiu-Tian-Feng; Liu, Qing; Wang, Peng; Li, Yafei; Zou, Ji-Jun

    2017-09-14

    Renewable high-density spiro-fuels are synthesized from lignocellulose-derived cyclic ketones for the first time, which show higher density, higher neat heat of combustion and lower freezing point compared with other biofuels synthesized from the same feedstock, and thus represent a new type of renewable high-density fuel attractive for practical applications.

  4. Fitness, Heart Disease, and High-Density Lipoproteins: A Look at the Relationships.

    ERIC Educational Resources Information Center

    McCunney, Robert J.

    1987-01-01

    The role of fitness in preventing coronary heart disease is explored. Research on high-density lipoprotein, which has been found to be one of the most critical determinants of risk, is reviewed. The relationship between fitness, high-density lipoprotein, and coronary heart disease is assessed, and clinical implications are spelled out. (MT)

  5. A high density genetic linkage map for rainbow trout (Onchorynchus mykiss) containing 47,839 SNPS

    USDA-ARS?s Scientific Manuscript database

    High-density SNP arrays have become the tool of choice for QTL mapping, genome-wide association studies and genomic selection. More recently, high-density linkage maps generated by SNP array data have proven to be crucial for the accurate assembly of scaffolds and contigs in whole-genome sequencing ...

  6. Flying-plate detonator using a high-density high explosive

    DOEpatents

    Stroud, John R.; Ornellas, Donald L.

    1988-01-01

    A flying-plate detonator containing a high-density high explosive such as benzotrifuroxan (BTF). The detonator involves the electrical explosion of a thin metal foil which punches out a flyer from a layer overlying the foil, and the flyer striking a high-density explosive pellet of BTF, which is more thermally stable than the conventional detonator using pentaerythritol tetranitrate (PETN).

  7. Nanostructure and thermal properties of melt compounded PE/clay nanocomposites filled with an organosilylated montmorillonite

    SciTech Connect

    Scarfato, Paola; Incarnato, Loredana; Di Maio, Luciano; Dittrich, Bettina; Niebergall, Ute; Böhning, Martin; Schartel, Bernhard

    2015-12-17

    In this work we report on the functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure and on its use as nanofiller in melt compounding of polyethylene nanocomposites. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and higher thermal stability with respect to most of commercial organoclays modified with alkylammonium salts. Its addition (at 5wt%) to two different polyethylene matrices (a low density polyethylene, LDPE, and a high density polyethylene, HDPE), processed in a pilot-scale twin-screw extruder, allowed to produce hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction. Thermogravimetric and differential scanning thermal analyses point out that the obtained nanocomposites do not show noticeable changes in the thermal behavior of both LDPE and HDPE, even if a slight reduction in the overall bulk crystallinity was observed in presence of the nanofillers.

  8. Nanostructure and thermal properties of melt compounded PE/clay nanocomposites filled with an organosilylated montmorillonite

    NASA Astrophysics Data System (ADS)

    Scarfato, Paola; Incarnato, Loredana; Di Maio, Luciano; Dittrich, Bettina; Niebergall, Ute; Böhning, Martin; Schartel, Bernhard

    2015-12-01

    In this work we report on the functionalization of a natural sodium montmorillonite (MMT) with (3-glycidyloxypropyl)trimethoxysilane by a silylation procedure and on its use as nanofiller in melt compounding of polyethylene nanocomposites. The obtained organosilylated clay showed higher interlayer spacing than the original MMT and higher thermal stability with respect to most of commercial organoclays modified with alkylammonium salts. Its addition (at 5wt%) to two different polyethylene matrices (a low density polyethylene, LDPE, and a high density polyethylene, HDPE), processed in a pilot-scale twin-screw extruder, allowed to produce hybrids with nanoscale dispersion of the filler, as demonstrated by X-ray diffraction. Thermogravimetric and differential scanning thermal analyses point out that the obtained nanocomposites do not show noticeable changes in the thermal behavior of both LDPE and HDPE, even if a slight reduction in the overall bulk crystallinity was observed in presence of the nanofillers.

  9. Static viscoelasticity of biomass polyethylene composites

    NASA Astrophysics Data System (ADS)

    Yang, Keyan; Cai, Hongzhen; Yi, Weiming; Zhang, Qingfa; Zhao, Kunpeng

    The biomass polyethylene composites filled with poplar wood flour, rice husk, cotton stalk or corn stalk were prepared by extrusion molding. The static viscoelasticity of composites was investigated by the dynamic thermal mechanical analyzer (DMA). Through the stress-strain scanning, it is found that the linear viscoelasticity interval of composites gradually decreases as the temperature rises, and the critical stress and strain values are 0.8 MPa and 0.03% respectively. The experiment shows that as the temperature rises, the creep compliance of biomass polyethylene composites is increased; under the constant temperature, the creep compliance decreases with the increase of content of biomass and calcium carbonate. The biomass and calcium carbonate used to prepare composites as filler can improve damping vibration attenuation and reduce stress deformation of composites. The stress relaxation modulus of composites is reduced and the relaxation rate increases at the higher temperature. The biomass and calcium carbonate used to prepare composites as filler not only can reduce costs, but also can increase stress relaxation modulus and improve the size thermostability of composites. The corn stalk is a good kind of biomass raw material for composites since it can improve the creep resistance property and the stress relaxation resistance property of composites more effectively than other three kinds of biomass (poplar wood flour, rice husk and cotton stalk).

  10. High-density renal cysts in autosomal dominant polycystic kidney disease demonstrated by CT

    SciTech Connect

    Levine, E.; Grantham, J.J.

    1985-02-01

    Unenhanced abdominal CT scans of 35 patients with autosomal dominant polycystic kidney disease (ADPKD) showed multiple high-density (58-84 HU) renal cysts in 42.9% of patients, occasional high-density cysts in 25.7%, and no high-density cysts in 31.4%. These high-density cysts were usually subcapsular and were more frequent in patients with markedly enlarged kidneys and flank pain at the time of CT. Follow-up CT often showed a reduction in cyst densities, although some cysts developed mural calcification and calcification of their contents. Renal carcinomas occur rarely in ADPKD and may occasionally be hyperdense. However, high-density cysts may usually be distinguished from carcinomas on CT by their smooth contours, sharp interfaces with renal parenchyma, homogeneity, and lack of contrast enhancement.

  11. Stability of serum high-density lipoprotein-microRNAs for preanalytical conditions.

    PubMed

    Ishikawa, Hiroaki; Yamada, Hiroya; Taromaru, Nao; Kondo, Kanako; Nagura, Ayuri; Yamazaki, Mirai; Ando, Yoshitaka; Munetsuna, Eiji; Suzuki, Koji; Ohashi, Koji; Teradaira, Ryoji

    2017-01-01

    Background Recently, several studies have shown that microRNAs are present in high-density lipoprotein, and high-density lipoprotein-microRNA may be a promising disease biomarker. We investigated the stability of high-density lipoprotein-microRNAs in different storage conditions as this is an important issue for its application to the field of clinical research. Methods microRNAs were extracted from the high-density lipoprotein fraction that was purified from the serum. miR-135 a and miR-223, which are known to be present in high-density lipoprotein, were quantified by quantitative real-time PCR. The influence of preanalytical parameters on the analysis of high-density lipoprotein-miRNAs was examined by the effect of RNase, storage conditions, and freezing and thawing. Results The concentrations of microRNA in high-density lipoprotein were not altered by RNase A treatment (0-100 U/mL). No significant change in these microRNAs was observed after storing serum at room temperature or 4℃ for 0-24 h, and there was a similar result in the cryopreservation for up to two weeks. Also, high-density lipoprotein-microRNAs were stable for, at least, up to five freeze-thaw cycles. Conclusions These results demonstrated that high-density lipoprotein-microRNAs are relatively resistant to various storage conditions. This study provides new and important information on the stability of high-density lipoprotein-microRNAs.

  12. Filling carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ugarte, D.; Stöckli, T.; Bonard, J. M.; Châtelain, A.; de Heer, W. A.

    Filling hollow carbon nanotubes with chosen materials opens new possibilities of generating nearly one-dimensional nanostrutures. One simple approach to fill nanotubes is to use capillarity forces. Here, we have studied the wetting and capillarity by metal salts. First, nanotubes were opened by oxidation in air; subsequently, nanotubes were immersed in molten salts. We have observed a size-dependence filling indicating a lowering of the cavity-salt interface energy with decreasing diameter. By expressing the wetting conditions as a function of polarizabilities, it is possible to predict the threshold diameter for capillary filling of different materials.

  13. Photolithographic Synthesis of High-Density DNA and RNA Arrays on Flexible, Transparent, and Easily Subdivided Plastic Substrates.

    PubMed

    Holden, Matthew T; Carter, Matthew C D; Wu, Cheng-Hsien; Wolfer, Jamison; Codner, Eric; Sussman, Michael R; Lynn, David M; Smith, Lloyd M

    2015-11-17

    The photolithographic fabrication of high-density DNA and RNA arrays on flexible and transparent plastic substrates is reported. The substrates are thin sheets of poly(ethylene terephthalate) (PET) coated with cross-linked polymer multilayers that present hydroxyl groups suitable for conventional phosphoramidite-based nucleic acid synthesis. We demonstrate that by modifying array synthesis procedures to accommodate the physical and chemical properties of these materials, it is possible to synthesize plastic-backed oligonucleotide arrays with feature sizes as small as 14 μm × 14 μm and feature densities in excess of 125 000/cm(2), similar to specifications attainable using rigid substrates such as glass or glassy carbon. These plastic-backed arrays are tolerant to a wide range of hybridization temperatures, and improved synthetic procedures are described that enable the fabrication of arrays with sequences up to 50 nucleotides in length. These arrays hybridize with S/N ratios comparable to those fabricated on otherwise identical arrays prepared on glass or glassy carbon. This platform supports the enzymatic synthesis of RNA arrays and proof-of-concept experiments are presented showing that the arrays can be readily subdivided into smaller arrays (or "millichips") using common laboratory-scale laser cutting tools. These results expand the utility of oligonucleotide arrays fabricated on plastic substrates and open the door to new applications for these important bioanalytical tools.

  14. High-temperature compatibility between liquid metal as PWR fuel gap filler and stainless steel and high-density concrete

    NASA Astrophysics Data System (ADS)

    Wongsawaeng, Doonyapong; Jumpee, Chayanit; Jitpukdee, Manit

    2014-08-01

    In conventional nuclear fuel rods for light-water reactors, a helium-filled as-fabricated gap between the fuel and the cladding inner surface accommodates fuel swelling and cladding creep down. Because helium exhibits a very low thermal conductivity, it results in a large temperature rise in the gap. Liquid metal (LM; 1/3 weight portion each of lead, tin, and bismuth) has been proposed to be a gap filler because of its high thermal conductivity (∼100 times that of He), low melting point (∼100 °C), and lack of chemical reactivity with UO2 and water. With the presence of LM, the temperature drop across the gap is virtually eliminated and the fuel is operated at a lower temperature at the same power output, resulting in safer fuel, delayed fission gas release and prevention of massive secondary hydriding. During normal reactor operation, should an LM-bonded fuel rod failure occurs resulting in a discharge of liquid metal into the bottom of the reactor pressure vessel, it should not corrode stainless steel. An experiment was conducted to confirm that at 315 °C, LM in contact with 304 stainless steel in the PWR water chemistry environment for up to 30 days resulted in no observable corrosion. Moreover, during a hypothetical core-melt accident assuming that the liquid metal with elevated temperature between 1000 and 1600 °C is spread on a high-density concrete basement of the power plant, a small-scale experiment was performed to demonstrate that the LM-concrete interaction at 1000 °C for as long as 12 h resulted in no penetration. At 1200 °C for 5 h, the LM penetrated a distance of ∼1.3 cm, but the penetration appeared to stop. At 1400 °C the penetration rate was ∼0.7 cm/h. At 1600 °C, the penetration rate was ∼17 cm/h. No corrosion based on chemical reactions with high-density concrete occurred, and, hence, the only physical interaction between high-temperature LM and high-density concrete was from tiny cracks generated from thermal stress. Moreover

  15. Properties of polymer blends filled with mixtures of conductive fillers

    NASA Astrophysics Data System (ADS)

    Thongruang, Wiriya

    2001-11-01

    High-density polyethylene (HDPE), ultrahigh molecular weight polyethylene (UHMWPE) and blends thereof are used to produce ternary and quaternary conductive polymer composites (CPCs) containing carbon black (CB), carbon graphite (G), carbon fiber (CF) and selected mixtures thereof to discern if polymer blends and mixed fillers yield appreciable advantages over CPCs composed of single polymers and/or single fillers. The effects of polymer blend composition and filler type, concentration and composition on electrical conductivity, composite morphology, mechanical properties and thermal behavior have been examined and correlated to establish meaningful structure-property relationships that can facilitate the rational design of efficient CPCs. Enhanced conductivity due to double-percolation is observed in ternary CPCs containing CB or G, whereas the concept of bridged double percolation is proposed to explain substantial conductivity increases in quaternary composites.

  16. 21 CFR 177.1615 - Polyethylene, fluorinated.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyethylene, fluorinated. 177.1615 Section 177... Contact Surfaces § 177.1615 Polyethylene, fluorinated. Fluorinated polyethylene, identified in paragraph... prescribed conditions: (a) Fluorinated polyethylene food-contact articles are produced by modifying...

  17. 21 CFR 177.1620 - Polyethylene, oxidized.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Polyethylene, oxidized. 177.1620 Section 177.1620... Contact Surfaces § 177.1620 Polyethylene, oxidized. Oxidized polyethylene identified in paragraph (a) of... following prescribed conditions: (a) Oxidized polyethylene is the basic resin produced by the mild...

  18. Porous polyethylene implants in facial reconstruction: Outcome and complications.

    PubMed

    Ridwan-Pramana, Angela; Wolff, Jan; Raziei, Ashkan; Ashton-James, Claire E; Forouzanfar, Tymour

    2015-10-01

    The aim of the present study was to assess the indications, results and complications of patients treated with porous polyethylene (Medpor(®)) implants in the Department of Oral and Maxillofacial Surgery of VU Medical Centre, Amsterdam over 17 years. A total of 69 high-density porous polyethylene implants (Medpor(®) Biomaterial; Porex Surgical, Newman, GA) were used in forty patients (22 males, 18 females). All patients were analysed for gender, age, diagnosis, indications for surgery, follow-up period and postoperative complications. A mean age of 34.1 years was observed. The main reason for implant surgery was post-traumatic functional impairment (27.5%). Most implants were placed at the mandibular angel and the orbital floor. Unsatisfactory appearance scored the highest in postoperative complications (10.1%) followed by infection rate (7.2%). Comparing the number of implants placed over the years and the incidence of complications, makes the overall complications rate of porous polyethylene very low. A consensus about antibiotic prophylaxis is needed. The objective measurements in patient satisfaction and proper implant design would be of great use.

  19. Rotational molding of pultruded profiles reinforced polyethylene

    NASA Astrophysics Data System (ADS)

    Greco, Antonio; Maffezzoli, Alfonso; Romano, Giorgio

    2014-05-01

    The aim of this paper is the production of fiber reinforced LLDPE components by rotational molding. To this purpose, a process upgrade was developed, for the incorporation of pultruded tapes in the rotational molding cycle. Pultruded tapes, made of 50% by weight of glass fibers dispersed in a high density polyethylene(HDPE) matrix, were glued on the internal surface of a cubic mold, and rotational molding process was run using the same processing conditions used for conventional LLDPE processing. During processing, melting of LLDPE powders and of HDPE allowed to incorporate the tapes inside rotational molded LLDPE. The glass fiber reinforced prototypes were characterized in terms of mechanical properties. Plate bending tests were performed on the square faces extracted from the rotational molded product. The rotational molding products were also subjected to internal hydrostatic pressure tests up to 10 bar. In any case, no failure of the cubic samples was observed. In both cases, it was found that addition of a single pultruded strips, which corresponds to addition of about 0.6% by weight of glass fibers, involved an increase of the stiffness of the faces by about 25%.

  20. Determination of Yttrium in High Density Silicon Nitride by Emission and X-Ray Fluorescence Spectroscopy.

    DTIC Science & Technology

    1981-08-01

    AD-AI07 596 ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA F/S 7/4 DETERMINATION OF YTTRIUM IN HIGH DENSITY SILICON NITRIDE BY EMI-ETCIU...AUG Al B H STRAUSS. UNCLASSIFIED AMMRC-TR-Al-39 N AMMRC TR 81-39 A ~LEVEL ’ t’- .- DETERMINATION OF YTTRIUM IN 1 HIGH DENSITY SILICON NITRIDE BY...DETERMINATION OF YTTRIUM IN HIGH DENSITY SILICON NITRIDE BY EMISSION AND X-RAY Final Report FLUORESCENCE SPECTROSCOPY 6 PERFORMING ORG. REPORT NUMBER 7. AUTHOR