The algorithmic, or consistent, tangent stiffness was introduced to improve the asymptotic convergence rate of the iterative correction algorithm for the evolutive analysis of elastoplastic structures. The original approach is based on a formulation of the elastoplastic law in terms of a plastic multiplier with an analysis which, in general, requires an operator inversion. A geometric description of the method, based on hypersurface theory, is proposed here to provide a clear picture of the algorithmic properties. An estimate of the tangent stiffness associated with finite step elastoplastic and elastoviscoplastic constitutive models is given. It is based on the properties of the projection operator on the elastic domain and avoids operator inversions retaining the beneficial properties of...
This thesis is concerned with the crystallisation behaviour of polymers near to a free surface or a buried interface. The properties of polymers are expected to differ significantly near to an interface (either with air or another polymer), due to the contributions of (a) chain configurations induced at the interface, and (b) different mobilities between interfacial regions and the bulk of the sample. For a semi-crystalline polymer, properties such as the degree of crystallinity and the crystallisation kinetics may be enhanced near to a free surface. Grazing incidence x--ray diffraction (GIXD) is used to investigate such effects in poly(ethylene terphthalate) (PET), showing that a lower crystallisation temperature is obtained at the surface, and the crystallisation kinetics are faster at the surface for all temperatures. It is proposed that in thin films of PET, this surface-induced ordering provides ...
The production of molecularly imprinted polymers (MIPs) for the recognition of C-terminal cholecystokinin pentapeptide (CCK-5) in the presence of metal ion is reported. The MIPs were produced under the same molar ratio of template to monomers (acrylamide, N,N'-methylene bisacrylamide) in the presence or absence of nitrilotriacetic acid-nickel (Ni-NTA) complex. Scanning electron microscopy images of MIPs were obtained in an attempt to correlate the adsorption characteristics with polymer's morphology. Subsequently Ni2+ was removed and substituted by other divalent ions such as Mg2+, Fe2+, Zn2+, Co2+ and Cu2+. It was found that polymers containing the metal ion complex with the order Fe-NTA, Ni-NTA and Cu-NTA presented lower dissociation constant values than the rest thus exhibiting stronger guest binding activity. The percentage of theoretical maximum binding sites Bmax was almost the same for these ...
A testing program has been conducted by the Westinghouse Hanford Company to confirm the baseline waste form selection for use in Waste Receiving and Processing (WRAP) Module 2A. WRAP Module 2A will provide treatment required to properly dispose of containerized contact-handled, mixed low-level waste at the US Department of Energy Hanford Site in south-central Washington State. Solidification/stabilization has been chosen as the appropriate treatment for this waste. This work is intended to test cement-based, thermosetting polymer, and thermoplastic polymer solidification media to substantiate the technology approach for WRAP Module 2A. Screening tests were performed using the major chemical constituent of each waste type to measure the gross compatibility with the immobilization media and to determine formulations for more detailed testing. Surrogate materials representing each of the eight waste types were prepared in the ...
The modification of polymers by radiation grafting has been utilized for several decades. The penetrability of gamma rays allows to modify the internal surfaces of porous materials retaining its mechanical properties. In recent years applications of these materials to obtain chromatographic supports and biocatalysts have been reported. In this work, we described the grafting of glycidyl methacrylate (GMA) onto a macroporous polysulfone polymer. Reproducible amount of grafting, from 10% to 60% was obtained by choosing favourable monomer concentration and gamma radiation doses from 6 kGy up. Afterwards, iminodiacetic acid (IDA) and amino phenyl arsine oxide (PAO) were covalently attached to the grafted polyGMA, in correspondence with the grafting degree. Later on, a recombinant histidin-patch thioredoxin protein (HP-rTrx) was immobilized onto this surface by two different ways, involving specific protein orientations. The first one involves an ...
Solid polymer fuel cell (SPFC) systems are compared to spark ignition (SI) engine power systems for utility vehicle applications. Utility vehicles provide crew and payload transport and electrical power at work sites lacking grid supply. The methodology emphasizes comparison on an equal service basis. Using power system component models and numerical analysis, power systems are designed using SI engine and SPFC technologies. The power systems are compared on the basis of fuel energy consumed and life cycle cost (LCC). Gasoline is the fuel for the SI engines, while liquid hydrogen is used for the SPFC. Three types of SPFC power system configurations are studied. The superior SPFC in terms of LCC is a fuel cell/battery hybrid where the fuel cell is sized to provide average driving power. Using today's technology, SPFC power systems have a lower fuel consumption but have higher capital costs and consequently lose to SI engine power ...
Multi-walled carbon nanotubes (MWNTs) were modified with poly(hexamethylene adipamide) (also known as Nylon 66) via a controlled polymer solution crystallization method. A 'nanohybrid shish kebab' (NHSK) structure was found wherein the MWNT resembled the shish while Nylon 66 lamellar crystals formed the kebabs. These Nylon 66-functionalized MWNTs were used as precursors to prepare polymer/MWNT nanocomposites. Excellent dispersion was revealed by optical and electron microscopies. Nitric acid etching of the nanocomposites showed that MWNT formed a robust network in Nylon 66. Non-isothermal DSC results showed multiple melting peaks, which can be attributed to lamellar thickness changes upon heating. The crystallite sizes L{sub 100} and L{sup 010} of Nylon 66, determined by WAXD, decreased with increasing MWNT contents. Isothermal DSC results showed that crystallization kinetics increased first and then decreased with increasing ...
Aminated poly(vinyl chloride) (PVC) membranes were prepared that had a Nernstian response over a wide range of pH. The reaction between PVC and methyl-piperazine (MePIP) in dimethylformamide (DMF) was studied over a wide range of time and temperature, and in the presence of the catalyst, potassium fluoride (KF). Time, temperature, and KF increased the nitrogen (N) content of the resulting polymers, but sometimes at the expense of decreasing their specific viscosities (molecular weights). Activation energies of processes that occurred in different temperature ranges were estimated assuming an Arrhenius relationship. A Nernstian response occurred once the N content approached to about 0.3 w/w %, and was accelerated by the presence of KF at elevated temperatures. Increasing the N content above about 3% led to a loss of the Nernstian response either because of an increase in the double bond content and a subsequent decrease in polymer mobility, or ...
A piezoelectric biosensor substrate useful for immobilizing biomolecules in an oriented manner on the surface of a piezoelectric sensor has a ladder polymer of polyacrylonitrile. To make the substrate, a solution of an organic polymer, preferably polyacrylonitrile, is applied to the surface of a piezoelectric sensor. The organic polymer is modifying by heating the polymer in a controlled fashion in air such that a ladder polymer is produced which, in turn, forms the attachment point for the biomolecules comprising the piezoelectric biosensor. 3 figs.
The aim of this work is to develop an industrial process for the synthesis of an extrusible electrolyte polymer for lithium batteries. From literature data and precise specifications the high molar mass EO/OP copolymers synthesis by coordinative catalysis has been studied in order to reach a high productivity and to minimize the treatment steps. Two catalytic systems have been studied: the aluminium alkoxide-based Vandenberg-type catalysis and the calcium alcoholate amides catalysis. The first catalysis performed in solution gives excellent results. Its adaptation to silicon supported catalysis leads to a directly usable polymer in suspension but the productivity falls down and remains to be optimized. The calcium amide catalysis in heptane suspension generates acceptable productivities but also a too high proportion of low molar masses. Various approaches have been studied to minimize this proportion due to the presence of secondary ...
One-dimensional core-shell polymer nanowires offer many advantages and great potential for many different applications. In this paper we introduce a highly versatile two-step template wetting process to fabricate two-component core-shell polymer nanowires with controllable shell thickness. PLLA and PMMA were chosen as model polymers to demonstrate the feasibility of this process. Solution wetting with different concentrations of polymer solutions was used to fabricate the shell layer and melt wetting was used to fill the shell with the core polymer. The shell thickness was analyzed as a function of the polymer solution concentration and viscosity, and the core-shell morphology was observed with TEM. This paper demonstrates the feasibility of fabricating polymer core-shell nanostructures using our two-step template wetting process and opens ...
Wood/polymer composites (WPC) have been prepared from pinewood with different compounds using gamma irradiation: butyl acrylate, butyl methacrylate, styrene, acrylamide, acrylonitrile, and unsaturated polyester styrene resin. The polymer loading was determined with respect to the compound concentration and the irradiation dose. The polymer loading increases generally with increase in the monomer or polymer concentration. Tensile and compression strength have been improved in the four cases, but no improvement was observed using unsaturated polyester styrene resin or acrylamide.
The polymer industry is a young industry that has undergone tremendous growth and change over the last sixty years. Many important discoveries in polymer science have been accidental. Most of the learning has been by trial and error and most of the understanding is still basically empirical--make a polymer material or compound and then put it to the test to study what it is and how it performs. This article provides an overview of what polymers and polymer compounds are, why they behave as they do, and it discusses several examples of failures of rubber and plastic components.
Presented are the investigation results of electrophysical and physico-mechanical properties of KLF-20, Viksint U-4-21, Viksint KT-73, UF-7-21, KG-184, KL-4, KL-16SE-305, VIAT-1 and PPK-21 sealants, irradiated with sources of continuous and pulse #gamma#-radiation, as well as pulse #gamma#-neutron radiation. It is shown that electrophysical and physico-mechanical properties of sealants after irradiation by continuous #gamma#-radiation up to 10"6 doses and pulse gamma-neutron radiation with neutron fluence of 10"1"3 neutron/cm"2 and #gamma#-radiation dose of 10"4R do not practically change. Electric conductivity and tangent of the angle of dielectric losses increase in the process of irradiation. Electric conductivity depends on irradiation type, is proportional to dose rate and does not depend on temperature and pulse duration.
A pillbox RF output window was developed for the L-band pulsed klystron for the Japanese Hadron Project (JHP) 1-GeV proton linac. The window was designed to withstand a peak RF power of 6 MW, where the pulse width is 600 {mu}sec and the repetition rate is 50 Hz. A high power model was fabricated using an alumina ceramic which has a low loss tangent of 2.5x10{sup -5}. A high power test was successfully performed up to a 113 kW RF average power with a 4 MW peak power, a 565 {mu}sec pulse width and a 50 Hz repetition rate. By extrapolating the data of this high power test, the temperature rise of the ceramic is estimated low enough at the full RF power of 6 MW. Thus this RF window is expected to satisfy the specifications of the L-band Klystron. (author).
Vegetable oils such as soybean oil will be converted to novel polymers using hydroformylation and other catalytic processes. These polymers can be used in the construction, automotive, packaging, and electronic sectors.
... Title : Wear Rate and Friction Coefficient in Liquid Nitrogen and Hydrogen of Steel Sliding on Polymer Laminates (Various Fabrics and Polymers. ...
... The addition of 0.5 pphr of fine thermal carbon black to the polymers gave good resistance to 500 hours of ultraviolet (UV) xposure in a Weather ...
Synthetic polymers and nanomaterials display selective phenotypic effects in cells and in the body that affect signal transduction mechanisms involved in inflammation, differentiation, proliferation,...Full Text Available
Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized under a high magnetic field of 10 T. The formation mechanism was investigated and discussed in detail. The synthesized samples were characterized by XRD, SEM, TEM, EMPA, and vector network analysis. By doping MnO2 with Fe, the relative complex permittivity of MnO2 and its corresponding loss tangent clearly decreases, but its relative complex permeability and its corresponding loss tangent markedly increases. Moreover, the theoretically calculated values of reflection loss show that with increasing the Fe content, the as-prepared Fe-doped MnO2 exhibits good microwave absorption capability. -- Graphical Abstract: Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first synthesized in a high magnetic field of 10 T via a simple chemical process. Display Omitted Highlights: ? Fe-doped MnO2 with a hollow sea urchin-like ball chain shape was first ...
Information is given on the theoretical principles underlying the technology of producing fibrous plastics and wood slabs. An examination is made of the most important characteristics of the physics and chemistry of polymers, and the properties of synthetic polymers used in the wood processing industry. A description is given of the chemical composition and properties of wood and its components as well as of synthetic polymers made of cellulose. The book is designed for students of technical schools of the wood and pulp processing industry. 7 references, 14 figures, 1 table.
A quantitative description is proposed for the depletion-induced slip thickness and velocity profile of a polymer solution near the wall-fluid interface in simple shear flow. The inhomogeneous polymer density profile at a flat wall is inserted into the equations of motion for the flow of a polymer solution near the flat wall. The theory is in quantitative agreement with simulation results. (letter to the editor)
The effect of the moisture content in amorphous polymers (PS, PVC, PMMA) on their electro-physical properties is considered. Analytical relationships describing the inflence of the external-field frequency and environmental relative humidity on the conductivity of the polymers are given. For the use of these polymers as active elements of moisture sensors, the moisture-resistive effect is estimated.
A wood-polymer composite has been produced by impregnating the wood with the monomer and subsequently polymerizing it by exposure to a gamma radiation source. To compare the improvement in creep deformation of the wood due to the polymer impregnation, a nonlinear Norton-Bailey isothermal mathematical function has been used to model the bending creep deformation of the wood-polymer composites. Results show that the impregnation significantly improves the creep resistance of the wood. The maximum creep resistance is obtained when the amount of polymer impregnation exceeds about 30%. An interfacial interaction between the wood cell wall and the polymer could explain the creep deformation improvement, as well as the maximum impregnation level beyond which little improvement occurs. The results indicate that polymer impregnation is a viable method for improving the ...
The passivity and breakdown of passivity of 1018 carbon steel in propylene carbonate (PC) and 1,2-dimethoxyethane (DME) mixtures with 0.5 molar lithium hexafluoroarsenate supporting electrolyte were examined via several electrochemical and surface analytical methods. The PC-DME/0.5 M LiAsF{sub 6} mixtures ranged from 10 to 90 mol % PC. The results from the PC/DME mixtures were compared to passivating mechanisms found in pure PC and DME solutions. In PC-rich mixtures, the breakdown of passivity occurred near the oxidation potentials of either organic solvent. Premature breakdown of the carbon steel in PC-DME mixtures occurred at sulfide inclusions as was observed earlier in PC/0.5 M LiAsF{sub 6} solutions although passive films attempted to form at these inclusion sites in mixtures containing at least 10 mol % DME. As the DME content increased in the PC-DME mixtures, the passive films formed on bare steel surfaces possessed an increasing polymer ...
The 177 underground storage tanks at the DOE's Hanford Site contain an estimated 180 million tons of high-level radioactive wastes. It is desirable to remove and concentrate the highly radioactive fraction of the tank wastes for vitrification. Resorcinol-formaldehyde (R-F) resin, an organic ion-exchange resin with high selectivity and capacity for the cesium ion, which is a candidate ion-exchange material for use in remediation of tank wastes. The report includes information on the structure/function analysis of R-F resin and the synthetic factors that affect performance of the resin. CS-100, a commercially available phenol-formaldehyde (P-F) resin, and currently the baseline ion-exchanger for removal of cesium ion at Hanford, is compared with the R-F resin. The primary structural unit of the R-F resin was determined to consist of a 1,2,3,4-tetrasubstituted resorcinol ring unit while CS-100, was composed mainly of a 1,2,4-trisubstituted ring. CS-100 shows the ...
The thermal properties of five types of radiation-induced wood-polymer composites based on a tropical hardwood, rubberwood (Hevea braziliensis), was studied by oxygen index measurement, differential thermal analysis (DTA) and thermogravimetry (TG). The DTA and TG curves of composites were different from those of rubberwood, which can be attributed to the presence of the incorporated polymers. Of the five composites, the one impregnated with bis(2-chloroethyl)vinyl phosphonate reduced the initial temperature of decomposition, increased the peak temperatures of exothermic reactions, and increased the char yield. Comparison with physical blends of rubberwood and the corresponding polymer provided some evidence of chemical interaction of wood and polymer in some of the composites. (author).
Surface doping of conjugated polymers is realized by depositing a thin layer of graphene oxide (GO) on top of the polymers. The high proton density and the unique 2D structure of GO facilitate the protonic surface doping of conjugated polymers to achieve high conductivities. This finding represents a new strategy for improving charge transport across the metal/conjugated polymer interface to achieve much improved performance in organic solar cells. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
Polymerizing effects of high energy radiation has been found suitable for preparation of wood-polymer composites. In the present work after evaluating polymer products that have been obtained by irradiation method, wood-polymer composites have been prepared by in situ polymerization of vinyl acetate, acrylic acid and acrylic acid/styrene mixture using two samples of Iranian hardwoods, Beech and Hornbeam. These woods and their composites have been tested for their physical and mechanical properties. The results have shown that chemical bonding between polymer and the cell wall component lead to better strength properties in the composites. (author).
A wood/polymer composite was produced by impregnating Ramin wood with methyl methacrylate monomer and subsequently polymerizing it by gamma irradiation. To assess the improvement in compression strength of the wood caused by the polymer impregnation, a microbuckling compression failure mechanism was used to model the compression failure of the composite. Such a mechanism was found to predict a linear relationship between the compression strength and the percentage polymer impregnation (by weight). Uniaxial compression test results at 45({plus minus}5)% and 90({plus minus}5)% relative humidity levels, after being statistically analysed, showed that such a linear relationship was valid for up to 100% polymer impregnation. (author).
A wood/polymer composite was produced by impregnating Ramin wood with methyl methacrylate monomer and subsequently polymerizing it by gamma irradiation. To assess the improvement in compression strength of the wood caused by the polymer impregnation, a microbuckling compression failure mechanism was used to model the compression failure of the composite. Such a mechanism was found to predict a linear relationship between the compression strength and the percentage polymer impregnation (by weight). Uniaxial compression test results at 45(#+-#5)% and 90(#+-#5)% relative humidity levels, after being statistically analysed, showed that such a linear relationship was valid for up to 100% polymer impregnation. (author).
The process of miniemulsification allows the generation of small, homogeneous, and stable droplets containing monomer or polymer precursors and magnetite which are then transferred by polymer reactions to the final polymer latexes, keeping their particular identity without serious exchange kinetics involved. It is shown that the miniemulsion process can excellently be used for the formulation of polymer-coated magnetic nanoparticles which can further be used for biomedical applications. The use of high shear, appropriate surfactants, and the addition of a hydrophobe in order to suppress the influence of Ostwald ripening are key factors for the formation of the small and stable droplets in miniemulsion and will be discussed. Two different approaches based on miniemulsion processes for the encapsulation of magnetite into polymer particles will be presented in detail.
We have carried out studies on the rheological properties of regenerated silk fibroin (RSF) solution using video microscopy. The degummed silk from the Bombyx mori silkworm was used to prepare RSF solution by dissolving it in calcium nitrate tetrahydrate-methanol solvent. Measurements were carried out by tracking the position of an embedded micron-sized polystyrene bead within the RSF solution through video imaging. The time dependent mean squared displacement (MSD) of the bead in solution and hence, the complex shear modulus of this solution was calculated from the bead's position information. An optical tweezer was used to transport and locate the bead at any desired site within the micro-volume of the sample, to facilitate the subsequent free-bead video analysis. We present here the results of rheological measurements of the silk polymer network in solution over a frequency range, whose upper limit is the frame capture rate of our camera, at ...
This report describes the cost, performance, and other key characteristics of an innovative technology for determining the presence or absence, and measuring the concentration, of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) in groundwater and soil, and in gaseous remediation process streams at hazardous waste sites. This new technology is Direct Sampling Ion Trap Mass Spectrometry (DSITMS). DSITMS introduces sample materials directly into an ion trap mass spectrometer by means of a very simple interface, such as a capillary restrictor or a polymer membrane. There is typically very little, if any, sample preparation and no chromatographic separation of the sample constituents. This means that the response of the instrument to the analytes or contaminants in a sample is nearly instantaneous, and that analytical methods based on DSITMS are fast. Analyses are typically completed in less than five minutes, and the ...
Wood-polymer composites (WPC) have been prepared of pinewood with different monomers using Gamma radiation: acrylamide, butyl acrylate, butyl methacrylate, styrene, acrylonitrile, and polyester. The polymer loading was determined as a function of monomer concentration and absorbed dose. The data show that polymer loading increases by increasing the monomer concentration. In two cases, BMA and polyester, the polymer loading decreases at high concentrations. This can be explained by the increase of the viscosity. Thus the diffusion of the compound into bulk would be slower. The absorbed dose seems to play a positive role in enhancing the polymer loading by increasing the dose. The mechanical properties, tensile and compression strength, have been improved in the most cases for all monomer concentrations or absorbed doses. Using polyester there was no improvement in the mechanical ...
...Polymer Fuel Cells Challenge Publications News Events Login Register Search Content type All Web pages Case studies Publications News Video Home ...Buildings Carbon capture & storage Combined heat & power Electricity transmission & distribution Energy storage Fuel cells Geothermal Hydroelectric Hydrogen Industry Lighting Marine Metering Nuclear Solar Transport Wind ...Home Emerging technologies Current focus areas Polymer Fuel Cell Challenge Polymer Fuel Cells Challenge The objective of the Polymer Fuel Cells Challenge is to develop,...prove and commercialise novel polymer fuel cell technologies that have the potential to deliver a step-change in overall system cost. What are ...
Ultrathin solid polymer electrolyte membranes containing sulfonic ester groups were prepared by polymerization of methyl benzenesulfonate and octamethylcyclotetrasiloxane in a glow discharge plasma. The sulfonic ester groups of the plasma polymer were transformed to lithium sulfonate groups by treatment with lithium iodide. Hybridization of this plasma polymer containing the lithium sulfonate groups with poly(ethylene oxide) (average Mw 300) resulted in the formation of a single lithium ion conductive film. The hybrid polymer electrolyte films were about 1 #mu#m thick, pinhole-free, adherent to various substrates, and showed ionic conductivities at 60 degrees C of the order of 10"- "6 S cm"- "1 (10"2 #OMEGA# cm"2 resistance per unit area of as-prepared solid polymer electrolyte). This material shows promise for electrochemical applications such as all solid-state lithium batteries, ...
The billiard motion inside an ellipsoid $Q \\subset \\Rset^{n+1}$ is completely integrable. Its phase space is a symplectic manifold of dimension $2n$, which is mostly foliated with Liouville tori of dimension $n$. The motion on each Liouville torus becomes just a parallel translation with some frequency $\\omega$ that varies with the torus. Besides, any billiard trajectory inside $Q$ is tangent to $n$ caustics $Q_{\\lambda_1},...,Q_{\\lambda_n}$, so the caustic parameters $\\lambda=(\\lambda_1,...,\\lambda_n)$ are integrals of the billiard map. The frequency map $\\lambda \\mapsto \\omega$ is a key tool to understand the structure of periodic billiard trajectories. In principle, it is well-defined only for nonsingular values of the caustic parameters. We present four conjectures, fully supported by numerical experiments. The last one gives rise to some lower bounds on the periods. These bounds only depend on the type of the caustics. We describe the geometric ...
This paper deals with the computation of sectional curvature for the manifolds of~$N$ landmarks (or feature points) in~$D$ dimensions, endowed with the Riemannian metric induced by the group action of diffeomorphisms. The inverse of the metric tensor for these manifolds (i.e.~the cometric), when written in coordinates, is such that each of its elements depends on at most~$2D$ of the~$ND$ coordinates. This makes the matrices of partial derivatives of the cometric very sparse in nature, thus suggesting solving the highly non-trivial problem of developing a formula that expresses sectional curvature in terms of the cometric and its first and second partial derivatives (we call this Mario's formula). We apply such formula to the manifolds of landmarks and in particular we fully explore the case of geodesics on which only two points have non-zero momenta and compute the sectional curvatures of 2-planes spanned by the tangents to such geodesics. The latter example gives ...
Device for separating and collecting ultrafine atomized powder from the gas stream of a gas atomizing apparatus comprises a housing having an interior wall oriented at an angle relative to horizontal so as to form a downwardly converging, conical expansion chamber, an inlet conduit communicated to the expansion chamber proximate an upper region thereof for receiving the gas stream, and an outlet proximate a lower region of the expansion chamber. The inlet conduit is oriented at a compound inclined angle (with respect to horizontal) selected to promote separation and collection of powder from the gas stream in the expansion chamber. The compound angle comprises a first entrance angle that is greater than the angle of repose of the powder on the housing interior wall such that any powder accumulation in the inlet conduit tends to flow down the wall toward the outlet. The second angle is selected generally equal to the angle of the housing interior wall measured from the same horizontal ...
In this paper, we obtain the following generalisation of isometric $C^1$-immersion theorem of Nash and Kuiper. Let $M$ be a smooth manifold of dimension $m$ and $H$ a rank $k$ subbundle of the tangent bundle $TM$ with a Riemannian metric $g_H$. Then the pair $(H,g_H)$ defines a sub-Riemannian structure on $M$. We call a $C^1$-map $f:(M,H,g_H)\\to (N,h)$ into a Riemannian manifold $(N,h)$ a {\\em partial isometry} if the derivative map $df$ restricted to $H$ is isometric; in other words, $f^*h|_H=g_H$. The main result states that if $\\dim N>k$ then a smooth $H$-immersion $f_0:M\\to N$ satisfying $f^*h|_H
The influences of compressive stress on the dielectric properties of (1 - x)Pb(In{sub 1/2}Nb{sub 1/2})O{sub 3}-xPbTiO{sub 3} (x = 0.1-0.5) ceramics was investigated in this study. The dielectric properties were measured under compressive stress applied parallel and perpendicular to electric field. The results clearly showed that the superimposed compression stress had pronounced effects on the dielectric properties of PIN-PT ceramics. In general, with increasing compressive stress the dielectric constant of the ceramics increased and decreased when the stress was applied parallel and perpendicular, respectively, to the electric field direction. The dielectric loss tangent, however, decreased in both stress cases. The observations were mainly interpreted in terms of competing influences of the domain switching through non-180 deg. domain walls, clamping of domain walls, de-ageing and the stress-induced decrease in the switchable part of spontaneous polarization.
This paper is about algebro-geometrical structures on a moduli space $\\CM$ of anomaly-free BV QFTs with finite number of inequivalent observables or in a finite superselection sector. We show that $\\CM$ has the structure of F-manifold -- a linear pencil of torsion-free flat connection with unity on the tangent space, in quantum coordinates. We study the notion of quantum coordinates for the family of QFTs, which determines the connection 1-form as well as every quantum correlation function of the family in terms of the 1-point functions of the initial theory. We then define free energy for an unital BV QFT and show that it is another avatar of morphism of QFT algebra. These results are consequences of the solvability of refined quantum master equation of the theory. We also introduce the notion of a QFT integral and study some properties of BV QFT equipped with a QFT integral. We show that BV QFT with a non-degenerate QFT integral leads to the WDVV equation---the ...
A a result of its former role as a producer of nuclear weapons components, the Rocky Flats Environmental Technology Site (RFETS), Golden, Colorado accumulated a variety of plutonium-contaminated materials. When the level of contamination exceeded a predetermined level (the economic discard limit), the materials were classified as residues rather than waste and were stored for later recovery of the plutonium. Although large quantities of residues were processed, others, primarily those more difficult to process, remain in storage at the site. It is planned for the residues with lower concentrations of plutonium to be disposed of as wastes at an appropriate disposal facility, probably the Waste Isolation Pilot Plant (WIPP). Because the plutonium concentration is too high or because the physical or chemical form would be difficult to get into a form acceptable to WIPP, it may not be possible to dispose of a portion of the residues at WIPP. The ...
Tropomyosin (Tm) is a conserved dimeric coiled-coil protein, which forms polymers that curl around actin filaments in order to regulate actomyosin function. Acetylation of the Tm N-terminal...Full Text Available
The main aim of the present study was to evaluate potential of ternary complexation (comprising of drug, cyclodextrin and polymer) as an approach for taste masking. For this purpose famotidine with...Full Text Available
This neutron reflectometry study evaluates the structures resulting from different methods of preparing polymer-cushioned lipid bilayers. Four different techniques to deposit a dimyristoylphosphatidylcholine...Full Text Available
A variety of albumin polymers were prepared and tested for binding with hepatitis B surface antigen (HBsAg): synthetic polymers cross-linked by either glutaraldehyde or carbodiimide; heat-aggregated...Full Text Available
Hydrogen cyanide polymerizes readily under a variety of conditions and significant prebiotic roles have been suggested for these polymers due to the abundance of HCN in universe. However, the structures...Full Text Available
The present article studies the electret state of polymers when moving through an alternating-current corona discharge plasma and investigates means for the determination of the transition of the polymeric material from the initial state of the electret when the corona-displaying voltage is increased.
This investigation clearly demonstrates that through partial impregnation techniques wood-polymer composites can be formed from the Pinus species grown in South Africa with a considerable saving in monomer costs without sacrificing the important physical properties of these materials.
Commercial introduction of new polymer materials for use as the electrolyte in solid tantalum and solid aluminum electrolytic capacitors is underway. ...
The chemistries of reactants, plasticizers, solvents and additives in an epoxy paint are discussed. Polyamide additives may play an important role in the absorption of molecular iodine by epoxy paints. It is recommended that the unsaturation of the polyamide additive in the epoxy cure be determined. Experimental studies of water absorption by epoxy resins are discussed. These studies show that absorption can disrupt hydrogen bonds among segments of the polymers and cause swelling of the polymer. The water absorption increases the diffusion coefficient of water within the polymer. Permanent damage to the polymer can result if water causes hydrolysis of ether linkages. Water desorption studies are recommended to ascertain how water absorption affects epoxy paint.
The compressive and bending strengths of a local tropical wood (Kapur-Dryobalanop sp.) were improved significantly by suitable impregnation of polymeric monomers (methylmethacrylate, methylmethacrylate - 5% dioxane and vinyl acetate) into the wood cellular structure and subsequent irradiation to form a wood-polymer composite. Statistical analysis revealed a linear relationship between increase in the strengths and the percentage of polymer impregnated. Fractographic analysis of the impact fractured surfaces under the scanning electron microscope showed the nature of the wood-polymer interface, which could account for the increase in the compressive and bending strengths. (author).
The concentrates of scattered organic matter???kerogen-like polymer, which is insoluble in acids and organic solvents???were isolated from rock samples taken at different depths from various stratigraphic units at the productive deposits of the Orenburg oil-gas condensate field using chemical methods. The chemical composition of the kerogen-like polymer and the concentrations of trace elements in it were studied. The regularities of evolutionary changes in the composition of the organic matter and the concentrations of trace elements in it in the order of the kerogen-like polymer and the following its consecutive derivatives were established: asphaltenes, ethanol-benzene tars, benzene tars, oils, and paraffins
This invention relates to a water soluble polymer and method for its preparation. The water soluble polymer exhibits superior thermal stability characteristics when used as an additive in aqueous drilling fluids. The polymer consists of a major portion of a catechol based monomer and a dicarboxylic acid. Other monomers and materials are added to enhance the functional characteristics of the drilling fluid additive. The method of this invention includes the mixing of monomers, polymerization of that mixture and optionally the steps of hydrolysis and sulfonation.
This paper presents ionic conductivity results obtained with polymer electrolytes and also with propylene carbonate solutions. The domain of electrochemical activity of this salt has been determined using cycle volt-amperometry in propylene carbonate. Preliminary experiments on the stability of the polymer electrolyte with respect to the lithium electrode have been carried out for a possible subsequent use in lithium batteries. (J.S.) 4 refs.
Results are presented of experiments on partial discharge in liquid nitrogen, including insulation breakdown characteristics of liquid nitrogen, partial discharge characteristics of composite insulation systems, lifetime of polymer films, impulse breakdown of polymer films in liquid nitrogen, etc. The partial discharge characteristics of liquid nitrogen are examined with increasing liquid-nitrogen pressure. It is concluded that a composite insulation structure of polymer film and liquid nitrogen can be used as effective electrical insulators at cryogenic temperatures.
Interpenetrated lattices (IPL) are combinations of reticulated polymers linked together by permanent crisscross. This structure is well-adapted to combined highly incompatible pairs of polymers. The in-situ sequential method has been applied successfully to the synthesis of ethylene poly-oxides / poly-siloxanes IPLs. The results concerning the preparation of such lattices and their behaviour as solid polymer electrolytes are presented in this paper. (J.S.) 24 refs.
Threshold pump intensity values leading to irreversible damage to colored laser elements based on elastic polymers were measured. The damage to colored elastomers is connected with absorbing microinclusions but is independent of molecular absorption. It is shown that damage to the elastomers has a pronounced threshold character in contrast to the microdamage accumulation effect in glassy polymers. The damage threshold for elastomers is 1.5 times higher, which is connected with the absence of microstresses (characteristics for organic glasses) in the specimens. 13 references.
The dual characteristics in the performance of polymers in wood-polymer composites systems have been pursued with regard to the resolution of mechanical anisotropy of wood and the improvement in dimensional stability. The objective of the present study is to pursue the polymerization mechanism in wood under electron beam irradiation and the temperature dependence of polymer-wood interactions induced at various levels of higher order structure of wood in order to understand the polymer performance. Veneers used in the study were of rotary-cut beech (Fagus crenata Blume) 0.65 mm thick. All samples were oven-dried in vacuo at 80/sup 0/C for 30 hr. The monomers used in the study were methyl methacrylate, styrene, acrylic acid, acrylonitrile, and unsaturated polyester. Experimental details are given. Results are given and discussed.
Ultra-thin, uniform, pinhole-free solid polymer electrolyte films having a fixed carboxylic ester group of approximately 1 {mu}m thickness were prepared by polymerization of methyl acrylate and tris(2-methoxyethoxy)vinylsilane in a glow discharge plasma. The carboxylic ester group of the plasma polymer were transformed to lithium carboxylate groups by treatment with lithium iodide. This process give a single lithium ion conductive film. These solid polymer electrolyte films showed ionic conductivities of the order of 10{sup -8} S cm{sup -1} (10{sup 4} {omega} cm{sup 2} resistance per unit area) at room temperature. (orig.).
This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The primary aim of this project is to obtain a basic scientific understanding of electrical transport processes at interfaces that contain an organic electronic material. Because of their processing advantages and the tunability of their electronic properties, organic electronic materials are revolutionizing major technological areas such as information display. We completed an investigation of the fundamental electronic excitation energies in the prototype conjugated polymer MEH-PPV. We completed a combined theoretical/experimental study of the energy relation between charged excitations in a conjugated polymer and the metal at a polymer/metal interface. We developed a theoretical model that explains injection currents at polymer/metal interfaces. We have made ...
Wood polymer composite (WPC) specimens were produced by impregnating a tropical wood with methyl methacrylate and subsequently polymerised by ..gamma..-irradiation. Beam specimens of varying weight percentages of polymer were then subjected to a three point bend creep test under a constant load condition, for 250, 300 and 350 N. A Norton-Bailey (power law) mathematical model was used to describe the creep behavior, with the creep components determined by a nonlinear regression analysis. Significant creep improvements were obtained from the composite specimens as compared to the untreated wood specimens. Results indicated that maximum creep resistance is obtained when the amount of polymer loading exceeded 30%. An interfacial interaction between the polymer and the wood cell wall was used to account for the behavior of the increase in the creep resistance.
Step-scan Fourier transform infrared spectroscopy in conjunction with impulse stress on polymer films has been used to monitor dynamic rheological responses in real time. A novel piezo-electrically-driven polymer microrheometer was employed to apply repetitive impulses to the polymer sample while time-domain spectra were recorded. Recent results include the study of both semi-crystalline polymers such as isotactic polypropylene (iPP) and elastomers such as Estane polyester/polyurethane copolymer and Kraton tri-block copolymer. The spectral changes of iPP are consistent with frequency-domain results. For iPP at room temperature, large differences in the response times of different absorption bands are not seen. However, the orientation response of the CH{sub 3} rocking mode is slightly slower than the responses of the backbone modes. To the authors` knowledge, this is the first reported successful ...
Polymers containing hydroquinone, catechol or their corresponding benzoquinones are a special class of redox polymers. Three pathways of their syntheses are possible: condensation polymerization of suitable monomers, addition polymerization of vinyl monomers containing redox moiety, and chemical attachment of redox unit onto pre-made polymeric matrix. A range of functionalized matrices have been employed such as polyethers, polyesters, polycarbonates, polyurethanes, polyamides and others. Protection of their phenolic functionality has conducted to chemically interesting redox polymer precursors. The presence of a redox moiety coupled with the extant functionalization of the polymer matrix makes the materials very valuable, of wide properties and consequently of vast applicability. For instance, in the oil field, some polymers such as carboxy-methyl-cellulose (CMC) are often applied ...
Complimentary spectroscopic, microscopic and electrochemical studies were performed to characterise the barrier properties as well as the interface structure of model iron substrates covered with thin plasma polymer films. Cathodic plasma polymers were deposited which show high barrier properties. The metal surface was pre-treated by a reducing or oxidising plasma. This allowed the adjustment of the oxidation state of the interface layer. The interface structure was characterised by means of X-ray photoelectron sputter profiles, infrared spectroscopy and the application of a Kelvin probe. The investigations show that the measured Voltapotential on the plasma polymer surface can be correlated with the oxidation state of the interface. Reducing plasmas lead to an almost oxide free surface. After deposition of the plasma polymer, this reduced state of the oxide is sensitive to re-oxidation of the interface ...
We describe the synthesis of metal-chelating polymers (MCPs) with four different pendant polyaminocarboxylate ligands (EDTA, DTPA, TTHA, DOTA) and an orthogonal end-group, either a fluorescein molecule or a bismaleimide linker for antibody attachment. Polymer characterization by a combination of (1)H NMR, UV/vis absorption measurements, and thermal gravimetric analysis (TGA) indicated that each chain of the fluorescein-terminated polymers contained one dye molecule. These polymer samples were loaded with three different types of lanthanide ions as well as palladium and platinum ions. The numbers of metal atoms per chain were determined by a combination of UV/vis and conventional ICP-MS measurements. The experiments with lanthanide ions demonstrated that a net anionic charge on the polymer is important for water solubility. These experiments also showed that at least one type of ...
S100A4, a member of the Ca(2+)-activated S100 protein family, regulates the motility and invasiveness of cancer cells. Moreover, high S100A4 expression levels correlate with poor patient survival in several cancers. Although biochemical, biophysical, and structural data indicate that S100A4 is a noncovalent dimer, it is unknown if two functional S100A4 monomers are required for the productive recognition of protein targets and the promotion of cell invasion. To address this question, we created covalently linked S100A4 dimers using a glycine rich flexible linker. The single-chain S100A4 (sc-S100A4) proteins exhibited wild-type affinities for calcium and nonmuscle myosin-IIA, retained the ability to regulate nonmuscle myosin-IIA assembly, and promoted tumor cell invasion when expressed in S100A4-deficient colon carcinoma cells. Mutation of the two calcium-binding EF-hands in one monomer, while leaving the other monomer intact, caused a 30-60-fold reduction in binding affinity for ...
We present a new approach for growing Si nanowires directly from a silicon substrate, without the use of a metal catalyst, silicon vapor or CVD gasses. The growth can be performed in a furnace type configuration at moderate temperatures or in localized regions by resistive heating. Since the silicon wires grow directly from the silicon substrate, they do not need to be manipulated nor aligned for subsequent applications. Wires in the 20-50 nm diameter range with lengths over 80 ?m can be grown by this technique. We have studied the effects of various growth parameters, including temperature, substrate orientation, initial sample cleaning and carrier gasses. Results indicate that most important parameters in the growth of the nanowires are the surface cleaning, the temperature and the type of carrier gas used. A model is proposed, which involves an oxide catalyst for the process, with the growth of the nanowires enabled by a significantly enhanced silicon surface diffusion process, due ...
Industrial applications of thermoplastic polymers are often limited by their poor adhesion properties. In this work the effect of surface oxyfluorination on the adhesion properties was investigated for polyethylene (PE), polyoxymethylene (POM), polybutylene terephthalate (PBT) and polyamide 6 (PA6). The adhesive joint strength was quantified using lap-shear tests. These results were correlated with the changes in the chemical composition of the surface, determined by X-ray photoelectron spectroscopy (XPS), in the surface free energy, measured by the contact angle method, and in the topography, using white-light confocal microscopy. The adhesive strength is strongly improved for all four polymers, but the degree of this increase depends on the polymer type. The surface free energy shows a similar trend for all four polymers. A high surface free energy exceeding 50 mN/m was observed after ...
Major factors that contribute to maximized impact resistance of semicrystalline engineering polymers include increased matrix molecular weight, minimal rubber glass-transition temperature, and optimal rubber-particle size, which depends on matrix type. Additional constraints are posed by the limitations of available materials and commercial requirements. Expanding the understanding of impact-modified crystalline engineering polymers will further extend their property ranges and utility. This chapter describes the phenomenology of certain factors, illustrates a new technique to measure rubber particle size, and contrasts the fracture mechanisms of poly(butylene terephthalate), nylon 66, and polyacetal. 49 refs., 24 figs.
This invention pertains to passivation-free solid-state rechargeable batteries composed of Li.sub.4 Ti.sub.5 O.sub.12 anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn.sub.2 O.sub.4, LiCoO.sub.2, LiNiO.sub.2 and LiV.sub.2 O.sub.5 and their derivatives.
This invention pertains to passivation-free solid-state rechargeable batteries composed of Li{sub 4}Ti{sub 5}O{sub 12} anode, a solid polymer electrolyte and a high voltage cathode. The solid polymer electrolyte comprises a polymer host, such as polyacrylonitrile, poly(vinyl chloride), poly(vinyl sulfone), and poly(vinylidene fluoride), plasticized by a solution of a Li salt in an organic solvent. The high voltage cathode includes LiMn{sub 2}O{sub 4}, LiCoO{sub 2}, LiNiO{sub 2} and LiV{sub 2}O{sub 5} and their derivatives. 5 figs.
Researchers are developing polymer-based coating systems to reduce scaling and corrosion of air-cooled condensers that use a geothermal fluid spray for heat transfer augmentation. These coating systems act as barriers to corrosion to protect aluminum fins and steel tubing; they are formulated to resist the strong attachment of scale. Field tests have been done to determine the corrosion and scaling issues related to brine spraying and a promising organometallic polymer has been evaluated in salt spray tests.
There is investigated the role of polymer layers on the metal surface of a fine filler in the formation of a PVC system with electrophysical properties. It is shown that a physicochemical polymer modification takes place under the surface active center influence. Thus, the surface layer properties (density and geometrical characteristics) differ from the PVC ones. The correlation between the electrophysical properties of the PVC composite and the surface layer in the range of the fine copper fraction of 0?11.3 vol % at E ? 106 V m?1 and a frequency response of 20?2 ? 105 Hz is determined. An explanation of the investigated relation is presented.
Fractal dimensional analysis was employed to obtain a quantitative measure of the morphology of polymer networks formed by UV irradiation induced polymerization of photo-reactive mesogenic monomers dissolved in a liquid crystal host medium. The fractal dimensions obtained, may be interpreted by polymer network growth following a percolation-like model for monomer concentrations well below the solubility limit. On passing the solubility limit, the polymerization process changes from a (radical chain) solution polymerization to a dispersion polymerization, with fractal dimensions decreasing and suggesting a cluster-cluster aggregation process for monomer concentrations above the solubility limit, similar to the aggregation of colloidal particles.
The effect of additives on the grafting of a monomer, butylmethacrylate (BA), into simul (a soft wood) has been studied using {sup 60}Co source at 3 Mrad. The enhancement of polymer loading (grafting) by the addition of minute amounts (1%) of oligomers and of polyfunctional monomers into simul + BA system has been further increased in the presence of acid and urea. The synergistic polymer loading yields by acid addition cause substantial decrease of tensile strength values of wood-plastic composite; but urea increases both polymer loading and tensile strength values synergistically in these systems. (author).
The effect of additives on the grafting of a monomer, butylmethacrylate (BA), into simul (a soft wood) has been studied using "6"0Co source at 3 Mrad. The enhancement of polymer loading (grafting) by the addition of minute amounts (1%) of oligomers and of polyfunctional monomers into simul + BA system has been further increased in the presence of acid and urea. The synergistic polymer loading yields by acid addition cause substantial decrease of tensile strength values of wood-plastic composite; but urea increases both polymer loading and tensile strength values synergistically in these systems. (author).
Systems MEMS sensors C11-20 Lifetime Distributions of Aluminum Electrolytic Capacitors C11-22 Adhesion Strength of Advanced Polymer Films for Flexible and Rigid...
Axon outgrowth and guidance to the proper target requires the coordination of filamentous (F)-actin and microtubules (MTs), the dynamic cytoskeletal polymers that promote shape change and locomotion....Full Text Available
The rejection thresholds of Phormia regina Meigen for twenty-four glycols have been determined. A definite relationship between the concentration of the test material and the distribution...Full Text Available
We prepared macromer-grafted polymers (MGPs) containing suitable polymer side chains for improving solubility and pyrene units for improving adsorption on multiwalled carbon nanotube (MWCNT) surfaces, and demonstrated that these MGPs act as MWCNT solubilizers that improve solubility of MWCNTs in typically poor solvents such as alkanes and that improve flowability of polymer/MWCNT composites. The polydimethylsiloxane (PDMS)-MGPs, synthesized using PDMS macromers and pyrene-containing monomers, improved solubility of MWCNTs not only in chloroform but also in hexane, which is a poor solvent for MWCNTs. Moreover, the addition of PDMS-MGP-adsorbed MWCNTs (MWCNT/PDMS-MGPs) to epoxy resin monomers or polybutylene terephthalate (PBT) drastically reduced the viscosity of the obtained epoxy resin mo...
The research carried out in Canada in the design of containers for the disposal of radioactive waste has focussed on spent nuclear fuel, even though the quantities of other currently stored radioactive wastes are substantially greater. Research carried out at the Royal Military College of Canada on the effects of mixed fields of radiation on high polymer adhesives and composite materials has shown that some polymers are quite resistant to radiation and could well serve in the fabrication of radioactive waste disposal containers. The purpose of this research was to determine if thermoplastic polymers could be used as superior materials to replace metals in the application of low and intermediate level radioactive waste disposal containers. Polymers have the advantage that they do not corrode like metals. The experimental methods, used in this research, focused on the effects of radiation on the ...
A kind of polymer-metal complex gel electrolyte is successfully prepared and is used in dye-sensitized solar cells. Raman and X-ray photoelectron spectroscopy confirm the structure of this complex and is found that the metal ion reacts with nitrogen in the polymer. This novel electrolyte shows apparent diffusion coefficient of iodide of 8.37 x 10-7 cm2 s-1 and the energy conversion efficiency of 6.10% when the amount of ZnI2 is 0.04 M. By studying the dissociation active energy of the inorganic salt in electrolytes, we find that the metal salts can dissociate more easily after reacting with polymer and as a result can provide extra free iodide ion. The cell maintains ca. 93% of its initial efficiency after 20 d without further sealing, which shows good long-time stability.
The use of solvating polymers of polyether type is an interesting solution for the manufacturing of high capacity lithium batteries with lithium metal anodes and which can operate at T > 50 deg. C. These operating conditions are perfectly compatible with electric-powered vehicle and stationary battery applications. In order to improve the ionic conductivity of polymer electrolytes, new aprotic and amorphous polyether lattices have been synthesized having a good conductivity but also good thermal, mechanical and electrochemical stabilities. Two type of 3-D polyether lattices obtained by reticulation of linear pre-polymers have been selected as host polymers: unsaturated poly-condensate and unsaturated co-polyethers. (J.S.) 18 refs.
A polymer-based additive that permanently reduces hardness in wood electrical transmission poles treated with a chromated copper arsenate (CCA) preservative, has been developed by a team of IREQ researchers. A three-phase project is being funded by Hydro-Quebec to evaluate the additive's effect on full-size hydro poles subjected to actual climatic conditions. The evaluation project is designed to test the CCA and the additive's degree of retention by analyzing the hardness measurements against climbing tests, and the washing resistance of the chromium, copper and arsenate in the CCA/polymer-additive treatment. CCA-treated poles will be used for reference. Accelerated aging tests to characterize the polymer's resistance to UV rays will also be part of the validation program.
The lithium carbon batteries studied in this paper use plasticized polymer electrolytes made with passive polymer matrix swollen by a liquid electrolyte with a high ionic conductivity (> 10{sup -3} S/cm at 25 deg. C). The polymers used to prepare the gels are polyacrylonitrile (PAN) and vinylidene poly-fluoride (PVdF). The electrochemical and physical properties of these materials are analyzed according to their composition. The behaviour of solid electrolytes with different materials of lithium ion insertion (graphite and LiNiO{sub 2}) are studied and compared to liquid electrolytes. The parameters taken into account are the reversible and irreversible capacities, the cycling performance and the admissible current densities. Finally, complete lithium ion batteries with gelled electrolytes were manufactured and tested. (J.S.) 2 refs.
A poly(ether urethane) (PEUR)/poly(ethylene oxide) (PEO)/SiO2 based nanocomposite polymer is prepared and employed in the construction of high efficiency all-solid-state dye-sensitized nanocrystalline solar cells. The introduction of low-molecular weight PEUR prepolymer into PEO electrolyte has greatly enhance the electrolyte performance by both improving the interfacial contact properties of electrode/electrolyte and decreasing the PEO crystallization, which were confirmed by XRD and SEM characteristics. The effects of polymer composition, nano SiO2 content on the ionic conductivity and I3- ions diffusion of polymer-blend electrolyte are investigated. The optimized composition yields an energy conversion efficiency of 3.71% under irradiation by white light (100 mW cm-2).
The development of 'Green Chemistry' requires new materials to replace the conventional organic chemistry by biological catalysts, to produce fine chemicals in an environmentally friendly manner. Microbial whole cells can be directly used as biocatalysts, providing a simple and cheap methodology since enzyme isolation and purification are avoided. High-density polyethylene (HDPE) is a very stable polymer though it can be activated by gamma radiation to induce grafting. Glycidyl methacrylate was grafted onto macroporous HDPE and PP in the range of 1-6%, proportional to the initial monomer concentration. Grafted polymers were further chemically modified with ethylenediamine to generate a cationic hydrogel of micron-size thickness onto the internal polymer surfaces. Modified polymers were able to immobilize Gram-positive and Gram-negative bacteria that can catalyze a chemical reaction as ...
The formation of nanoparticles during the radiation-induced chemical reduction of silver ions, copper ions, and nickel ions in films based on poly(acrylic acid)-poly(ethylenimine) complexes are studied via electron microscopy. This approach allows preparation of composites containing nanoparticles that are randomly distributed in the polymer matrix and materials with a regular spatial distribution of nanoparticles across the film thickness and in subsurface layers. The structure of metal-polymer hybrid materials is dependent on the irradiation conditions, the type of reduced metal ions, and their initial content in polymer matrices. The ratio between the rate of nucleation and the rate of growth of nanoparticles in the matrices of interpolyelectrolyte complexes depends on the intensity of ...
Abstract The effects of the type of coupling agent and virgin polypropylene (PP) content on the mechanical properties and water absorption behavior of recycled low-density polyethylene/wood flour (WF) composites were investigated. The fractured surfaces of these recycled wood/plastic composites (rWPCs) were examined to gain insight into the distribution and dispersion of WF within the polymer matrix. The results indicate that the use of 100% recycled polymer led to inferior mechanical properties and to a greater degree of moisture absorption and swelling when compared to recycled polymer-virgin PP wood/plastic composites. This could have been related to the poor melt strength and inferior processability of the recycled polymer. The extent of improvement of the mechanical properties depende...
Solar cells consisting of polymer layers sandwiched between a transparent electrode on glass and a metal top electrode are studied using dynamic time-of-flight secondary ion mass spectrometry (TOF-SIMS) in dual-beam mode. Because depth profiling of polymers and polymer-metal stacks is a relatively new field the craters were thoroughly investigated by environmental SEM (ESEM), interferometry, surface profilometry and tapping mode AFM. A huge increase in crater bottom roughness was observed when starting from the aluminum top layer going in depth, resulting in a loss of depth resolution. It is shown that layer-to-layer diffusion and contaminants at buried interfaces can be extracted from the depth profiles when taking into account the loss of depth resolution.
Wood plastic composites (WPCs) are comprised of wood flour and thermoplastic polymer. The matrix is typically high-density polyethylene, poly (vinyl chloride), or polypropylene. The effect of morphology and micromechanics of wood flour particles on the mechanical performance of the bulk composite is a relatively unexplored area. The knowledge about the in situ properties of wood particles and the interfacial properties between the wood particles and the polymer matrix in the bio-composites is very limited. The objective of this work is to characterize the full-field deformation and strain distribution in and around wood particles embedded in polymer matrix. The mechanical tests are performed in small-scale tensile loading stage on thin composite samples containing 1-3 wood particles orient...
A rigorous solution for the spectrum of a quasioptical cylindrical cavity resonator with a randomly rough side boundary has been obtained. To accomplish this task, we have developed a method for the separation of variables in a wave equation, which enables one, in principle, to rigorously examine any limiting case-from negligibly weak to arbitrarily strong disorder at the resonator boundary. It is shown that the effect of disorder-induced scattering can be properly described in terms of two geometric potentials, specifically, the "amplitude" and the "gradient" potentials, which appear in wave equations in the course of conformal smoothing of the resonator boundaries. The scattering resulting from the gradient potential appears to be dominant, and its impact on the whole spectrum is governed by the unique sharpness parameter ?, the mean tangent of the asperity slope. As opposed to the resonator with bulk disorder, the distribution of nearest-neighbor spacings (NNS) ...
Although some polymer conductors of electricity (ex. Polyanilines) are materials known for more than 100 years, only recently have the interesting chemical, electrical and optic properties of their insulating and conducting forms been recognized. Advances made in the chemistry of polymer conductors have also led to improvements in processing them. This work studies a practical application of these materials: the use of polymer conductors for the remote welding of insulating thermoplastic polymers, using energy from microwaves for the local heating of the union. Many thermoplastics (for ex. Polyethylene) do not absorb, or absorb very little, energy from microwaves. Different conductor materials (conductor polymers, carbon nanotubes), however, heavily absorb energy from microwaves with the resulting heating. In this way the welding zone can be heated without affecting the rest of the ...
Since several years we apply the radiation-grafting technique to prepare polymeric membranes for application in polymer electrolyte fuel cells (PEFCs). Our investigations presented here focus on changes in toughness of these materials after the various synthesis steps and the importance of membrane toughness for their application in PEFCs. (author) 2 figs., 4 refs.
In earlier works, the inelastic mean free path (IMFP) of electrons was determined by elastic peak electron spectroscopy (EPES) using Ni and Ag reference standard samples, but fully neglecting surface excitation. Surface excitation that is characterized by the surface excitation parameter (SEP), and may affect considerably the elastic peak for the sample and the reference material. The SEP parameters of selected conducting polymers (polythiophenes, polyaniline and polyethylene) were determined by EPES using Si and Ge reference samples. Experiments were made with a hemispherical analyzer of energy resolution 100-200 meV in the E = 0.2-2.0 keV energy range. The composition of the sample surfaces was determined by in situ XPS, their surface roughness by AFM. The experimental SEP parameter data of eight polymer samples were determined by our new procedure, using the formulae of Chen and Werner et al. in the E = 0.2-2.0 keV energy range. The trial ...
Esters of dihydric alcohols with alkenylphosphonic or alkenylphosphinic acids which are polymerizable by free radicals are described. They are combined with polymer binders, in particular water-soluble polymers, and photoinitiators forming free radicals to give photopolymerizable mixtures which are suitable for the production of photoresists and printing plates. The mixtures display low heat-sensitivity and have long shelf lives. (author) 1 tab.
The use of WPC as an important insulating material is studied by determining its dielectric constant. The variation of dielectric constant with moisture content is also investigated. Preliminary results show that all untreated woods studied have a higher dielectric constant than their polymer composites with the exception of Kapur and Keruing. It is therefore postulated that the presence of polymers has led to a decrease in the number of polarizable units. Such a material may be useful commercially.
The physics and technology of a new class of efficient composite piezoelectrics are described. This material combines nanostructured and micropiezoelectric matrix composites. They consist of a polymer matrix, an insulating nanodimensional phase, and a microdimensional piezoelectric phase. It is shown that the nanostructuring of the near-surface region of polymer-PZT piezoelectric composites greatly improves their piezoelectric, mechanical, and electromechanical characteristics. A plausible mechanism underlying this effect is suggested.
The feasibility of using a thermoplastic-powder metallurgy technique for the fabrication of porous niobium rods was investigated. Some early problems were overcome to successfully extrude the polymer coated niobium powder into long lengths. The effects of certain process variables were investigated. Residual porosity and extrusion pressure were found to be regulated by the polymer fraction. The procedures for taking the extruded polystyrene--niobium rods through the heat treatments to the final, tin infiltrated stage are explained.
Water transport in the ionomeric membrane, typically Nafion{reg_sign}, has profound influence on the performance of the polymer electrolyte fuel cell, in terms of internal resistance and overall water balance. In this work, high resolution neutron imaging of the Nafion{reg_sign} membrane is presented in order to measure water content and through-plane gradients in situ under disparate temperature and humidification conditions.
Radiation processed wood-polymer composites (WPC) can replace conventional wood in many industrial applications. However, for proper utilization of the composites, adequate testing and evaluation programmes are essential. The paper briefly describes the development of WPC at the Bhabha Atomic Research Centre, Bombay, and the evaluation of WPC for various applications in greater details. The various mechanical properties and their significance in overall performance of WPC are also discussed. (author).
We have measured, by {sup 1}H and {sup 13}C nuclear magnetic resonance (NMR), the percent deuteration, the tacticity and the purity of several polymers and one solvent used in the preparation of microcellular foams. The percent deuteration was measured for polystyrene, polyacrylonitrile and polyethylene. The tacticities of polystyrene and polyacrylonitrile were determined. The purity and degradation products of polyacrylonitrile and maleic anhydride were examined. This report documents the experimental procedures and results of these measurements.
A membrane process utilizing dialysis and selective complexation by water-soluble polymers has been developed. This process, termed affinity dialysis, has been shown to be selectively extract and concentrate both cations and anions in a manner similar to ion exchange or solvent extraction. The selective removal of calcium from sodium with selectivity of about 30, removal of chromate ion from dilute streams, and separation of transition metal ions such as Cu/Fe and Cu/Zn have all been successfully demonstrated. Effects of different polymers, polymer concentration, temperature, and flow rates have been studied. The effect of increased polymer concentration is to increase product concentration if appropriate changes in feed, polymer solution, and strip flow rates are made. A continuous polymer solution recycle and regeneration system has been constructed and ...
The use of WPC as an important insulating material is studied by determining its dielectric constant. The variation of dielectric constant with moisture content is also investigated. Preliminary results show that all untreated woods studied have a higher dielectric constant than their polymer composites with the exception of Kapur and Keruing. It is therefore postulated that the presence of polymers has led to a decrease in the number of polarizable units. Such a material may be useful commercially. (author).
Nanoimprinting is a fast-growing technique for nanoscale patterning. One of the remaining issues in nanoimprinting is the removal of the residual layer after nanoimprinting. Traditionally the residual layer is removed by an oxygen reactive-ion etching (RIE) step. The need for a vacuum environment and dedicated equipment in this step lowers the throughput and increases the cost of the nanoimprinting process. It also prevents the possibility of patterning isolated functional polymers because oxygen RIE destroys the functional materials. In this work, novel nanoimprinting schemes are developed to nondestructively remove the residual layer in thermal nanoimprinting by solvent developing and dewetting. Combined with a transfer-bonding technique, three-dimensional polymer scaffolds are achieved. The techniques developed here eliminate the RIE step in thermal nanoimprinting and are compatible with roller nanoimprinting for large-scale patterning of ...
Composites based on pure gypsum and polyester-styrene resin have been prepared using various doses of gamma radiation. Some physical properties of the prepared composites and the influence of irradiation dose on it have been studied as: compression strength, hardness, thermal decomposition temperature in nitrogen or oxygen, and the change in weight in aqueous solutions with different pH values. The glass transition temperature of the pure polymer and the composites increases with increasing the irradiation dose up to a plateau, and the glass transition temperature of the pure polymer is lower than that of the composites. The irradiation dose does not seem to affect the decomposition temperature of the pure polymer or the composites significantly and the decomposition temperature in presence of nitrogen is higher than that in presence of oxygen. Increasing the irradiation dose leads to an enhancement of the compression ...
The adverse effect of moisture diffusion on the properties of wood has been one of the main weaknesses of wood. Using a gamma irradiation method, wood-polymer composites have been produced which exhibit significant improvement in mechanical properties like compression, creep deformation and creep rupture particularly at high humidity. It has been thought that the impregnation of polymer into the wood has affected the moisture diffusion in the wood, so that its adverse effects on the mechanical properties has been reduced. In this report the apparent diffusion coefficients of a Ramin wood impregnated with varying amounts of polymethyl methacrylate (PMMA) were determined using a Fick's law approach. An initial linear relationship was found for impregnation of up to 70% PMMA, after which the diffusion coefficient levels off to a maximum value, for the three environmental relative humidity levels of 40, 60 and 90({plus minus}5)%. The ...
The adverse effect of moisture diffusion on the properties of wood has been one of the main weaknesses of wood. Using a gamma irradiation method, wood-polymer composites have been produced which exhibit significant improvement in mechanical properties like compression, creep deformation and creep rupture particularly at high humidity. It has been thought that the impregnation of polymer into the wood has affected the moisture diffusion in the wood, so that its adverse effects on the mechanical properties has been reduced. In this report the apparent diffusion coefficients of a Ramin wood impregnated with varying amounts of polymethyl methacrylate (PMMA) were determined using a Fick's law approach. An initial linear relationship was found for impregnation of up to 70% PMMA, after which the diffusion coefficient levels off to a maximum value, for the three environmental relative humidity levels of 40, 60 and 90(#+-#5)%. The phenomenon could be ...
The kinetics of electrical breakdown of thin (15-70 ?m) layers of polymers and ceramics in a constant-sign field at 77-480 K has been investigated. The temperature dependences of the longevity (breakdown waiting time) of both dielectrics have been found to be similar to each other. At elevated temperatures, the longevity of the dielectrics varies exponentially with increasing temperature, and at reduced temperatures, it is temperature-independent (there is an athermal plateau). The mechanisms of elementary events controlling the process of preparation of the dielectrics for breakdown at elevated and reduced temperatures are the thermal-fluctuation over-barrier electron transition from trap to trap and the tunneling (under-barrier) transition, respectively. The hopping electron transport in the field direction gives rise to critical space charges causing breakdown of the dielectrics. The transition barrier heights (trap depths) have been determined. The ...
A non-synthetic polymer material, polyterpenol, was fabricated using a dry polymerization process namely RF plasma polymerization from an environmentally friendly monomer and its surface, optical and electrical properties investigated. Polyterpenol films were found to be transparent over the visible wavelength range, with a smooth surface with an average roughness of less than 0.4 nm and hardness of 0.4 GPa. The dielectric constant of 3.4 for polyterpenol was higher than that of the conventional polymer materials used in the organic electronic devices. The non-synthetic polymer material was then implemented as a surface modification of the gate insulator in field effect transistor (OFET) and the properties of the device were examined. In comparison to the similar device without the polymer insulating layer, the polyterpenol based OFET device showed significant improvements. The addition of the ...
We study the emission zone in a single-layer polymer light-emitting diode. The emission zone is found by studying the angular distribution of the electroluminescence. The emission is modeled by accounting for optical interference. We account for birefringence of the anode layer in our model. The active polymer was, however, found to be isotropic. The anode consists of a single-layer of the conducting polymer complex poly(3,4-ethylenedioxythiophene) and poly(styrene sulfonate) (PEDOT-PSS), with enhanced conductivity. As a cathode we use plain aluminum. By using only PEDOT-PSS we avoid having a thin metal layer or indium-tin-oxide as the anode in the path of the escaping light. The active material is a substituted polythiophene with excellent film forming properties. A comparison between the experimental and calculated angular distribution of light emission from a single-layered polymer light-emitting ...
This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). Functionally graded material is an enabling technology for lightweight body armor improvements. The objective was to demonstrate the ability to produce functionally graded ceramic-polymer and ceramic-metal lightweight armor materials. This objective involved two aspects. The first and key aspect was the development of graded-porosity boron-carbide ceramic microstructures. The second aspect was the development of techniques for liquid infiltration of lightweight metals and polymers into the graded-porosity ceramic. The authors were successful in synthesizing boron-carbide ceramic microstructures with graded porosity. These graded-porosity boron-carbide hot-pressed pieces were then successfully liquid-infiltrated in vacuum with molten aluminum at 1,300 C, and with liquid polymers at ...
In this paper, the compulsory site requirements and the site design assumptions which are being used for the present ITER plant are briefly described. A set of different parameters from the site design assumptions is also described, which was adopted as an additional exercise for cost sensitivity analysis of the ITER plant for these parameters. (orig.) 1 refs.
In this paper, the compulsory site requirements and the site design assumptions which are being used for the present ITER plant are briefly described. A set of different parameters from the site design assumptions is also described, which was adopted as an additional exercise for cost sensitivity analysis of the ITER plant for these parameters. (orig.)
By means of an audio frequency plasma polymerisation ultra-thin gradient plasma polymer layers were deposited on zinc and zinc-coated iron. The aim was to generate an interfacial polymeric layer which bonds to an oxidised metal as well as to a subsequently applied organic coating and acts as an interfacial barrier layer for ions and water. Surface modifications were done in an in situ plasma cell with infrared reflection absorption spectroscopy (IRRAS). The zinc surface was first activated by an oxygen plasma to provide a freshly oxidised and contamination free oxide surface. The intermediate stages of the surface reactions could be revealed. Carbon dioxide molecules as oxidation products adsorbed on the growing zinc oxide and were desorbed at a later stage. An organosilicon plasma polymer was deposited directly on top of the oxide layer from a hexamethyldisilane (HMDS) plasma. Afterwards a cyclohexene (CHEX)/hexamethyldisilane co-plasma ...
This paper explores for the first time the post-radiation-induced-graft polymerization on solid substrate using reversible addition-fragmentation transfer (RAFT) mechanism. Radiation-induced graft polymerization onto polymers is a potentially interesting technique to create easily new materials from highly resistant polymers, e.g. surface graft polymerization of acrylic acid (AA) onto poly(vinylidene difluoride) (PVDF) improves its surface properties without losing its excellent mechanical properties. As a consequence of the radical nature of the polymerization processes it is difficult to control molecular weight of grafted chains, and therefore design and standardize the properties of the final product. RAFT polymerization is a suitable method to obtain monodisperse polymers. The ability of the RAFT agents to control the polymer chain length could be an interesting approach to improve the grafted ...
This process for the preparation of nonaqueous dispersions of water-soluble polymerisates concerns compounds obtained by polymerization of water-soluble unsaturated ethylenic monomers in an emulsion of water in oil. The product is then dewatered to a maximum residual water content of 5% by means of microwaves. The process is azeotropic. The polymer has a molecular weight between 100,000 and 50,000,000, preferably between one and 10 million. Before treating with microwaves, the mixture is concentrated by conventional means until it has a polymer concentration between 20 and 65%, preferably between 40 and 60%. The microwaves have a wavelength between 0.1 and 30 cm. These polymer dispersions can be used in drilling fluids and as additives in tertiary oil recovery. 4 claims.
Before electroless plating, polymer surfaces must be sensitized and/or activated by using either the conventional two-step or one-step process. The latter stage is a compulsory one to make such surfaces catalytic, e.g., for Ni-P deposition. These processes are performed here using O{sub 2}, NH{sub 3}, or N{sub 2} plasma pretreatments. Reaction mechanisms are proposed for each of the processes and for each type of surface considered (oxygenated or both oxygenated and nitrogenated by the plasma treatment). Direct palladium chemisorption onto nitrogenated groups is highlighted. This allows one to simplify the process making the surface catalytic via elimination of the use of SnCl{sub 2} and to extend the method to any polymer. An additional interest of the plasma treatments, besides their high efficiency in grafting chemical functions, is to perform this grafting at will on selected areas which results in selective metallization.
All-atom molecular dynamics simulations were used to study the morphology of polymer/inorganic composite particles prepared by heterocoagulation. The results were also compared to those of our previous study of the preparation of TiO2/poly(acrylic acid-co-methyl methacrylate) and Fe3O4/polystyrene composite particles. In the simulation system, polymer or inorganic particles were simulated by surface-charge-modified C60 or Na atoms. Through a combination of analysis of the radial distribution functions of charged atoms and snapshots of the equilibrated structure, three kinds of particle distributions were observed under different conditions. When the polymer and inorganic particles had opposite surface charges and their sizes were very different, the composite morphology showed a core-shell...
Nanocapsules coated by medicinal plants have many applications in drug manufacturing. Medicinal plants can be loaded on nanocapsules with polyesteric triblock copolymer poly ethylene glycol-poly butylene adipate-poly ethylene glycol (PEG-PBA-PEG) as shell and olive oil can be introduced as a core of nanocapsules by a method known as polymer deposition solvent evaporation method. In this research, first, certain amount of polymer, Matricaria recutita extract and olive oil were mixed with acetone and then, water was added to the solution using magnetic stirrer. After which the acetone was removed by vacuuming and finally nanocapsules were found by freezing-drier. The study showed the size of nanocapsules depends on variety of factors such as the ratio of polymer to oil and concentration of p...
The BT-EdF-CEA consortium for the development and the performance improvement of lithium/polymer batteries has carried out a safety analysis of the industrial risk and the risk for users linked with this new technology. The process chosen for the manufacturing of lithium/polymer batteries does not generate any particular risk of personnel or environmental contamination. Security tests have permitted to observe and analyze the behaviour of 4 Ah elements during thermal shocks, perforation and crushing, and during external short-circuit on 20 Ah elements. These tests demonstrate the great thermal stability and the excellent behaviour of batteries in the case of partial destruction. (J.S.) 2 refs.
We discuss theoretically and numerically the intramolecular form factor $F(q)$ in dense polymer systems. Following Flory's ideality hypothesis, chains in the melt adopt Gaussian configurations and their form factor is supposed to be given by Debye's formula. At striking variance to this, we obtain noticeable (up to 20%) non-monotonic deviations which can be traced back to the incompressibility of dense polymer solutions beyond a local scale. The Kratky plot ($q^2F(q)$ {\\it vs.} wavevector $q$) does not exhibit the plateau expected for Gaussian chains in the intermediate $q$-range. One rather finds a significant decrease according to the correction $\\delta(F^{-1}(q)) = q^3/32\\rho$ that only depends on the concentration $\\rho$ of the solution, but neither on the persistence length or the interaction strength.
Considerable interest has focused recently on the use of lignocellulosic fibers as a reinforcement for thermoplastic polymers. The combination of these dissimilar materials, however, is characterized by a widespread incompatibility that leads to a weak fiber/polymer interface and poor performance properties for the composite. In an effort to improve compatibility a number of fiber surface modification approaches have been investigated including plasma, ozone, and polymer grafting treatments. Evaluation of adhesion improvements has been complicated by processing variables that are difficult to control. This paper will discuss the use of the-micro-debond test in quantifying the interfacial shear strength (ISS) in wood fiber/polystyrene composites. Wood fibers were modified to different degrees with styrene-maleic anhydride copolymers that varied in their composition. The effect of fiber modification on surface energetics was ...
A sulfonated fluoroalkyl graft polymer (FGP) membrane was prepared as a polymer electrolyte. First, the FGP membrane was grafted with styrene under UV irradiation. The grafted FGP was then sulfonated to functionalize it for proton conductivity. The grafting degree of the membrane increased with increasing grafting time during UV irradiation. The proton conductivity of the membrane increased with increasing grafting degree. The swelling ratio was independent of the grafting time, however, the water uptake increased with increasing grafting degree. Based on these results, it was found that the UV-initiated styrene grafting occurred along the membrane thickness direction. Moreover, the membrane was embedded within the glass fibers of the composite. This composite electrolytic membrane had 1.15 times the proton conductivity of a Nafion 117 membrane.
Abstract:- In recent years, the study of polymer/clay nanocomposites has attracted major research and commercial interests due to their superior mechanical and thermal properties to those of the neat polymers. Numerical modelling is an advantageous approach to understand the material behaviour. In this work a symmetric two dimensional finite element model is developed to simulate the fully exfoliated Polymer/Clay nanocomposite behaviour and evaluate its- before stress stress-strain curve. The Nylon 66/Clay in this study has a nonlinear elastic behaviour. The influence of volume fraction and aspect ratio of clay platelet (defined as the ratio of the particle length to the particle thickness) on the tensile behaviour of exfoliated Nylon 66/clay nanocomposite is investigated with the aid of n...
The performance of different polymers used to flocculate red mud particulate materials in the Bayer process can be evaluated on the basis of their efficiency to achieve adequate settling velocities and turbidity levels. In this study, three commercially available flocculants are evaluated under typical conditions found in the last washer of a Bayer plant. The different shear levels are produced by using a modified Couette flow system. Great differences are noticed in the performance of the polymers when they are compared at different dosages and at different shear rate levels. The data collected also suggests that conventional cylinder settling tests may not be adequate to measure the performance of certain types of polymers. (author)
The performance of different polymers used to flocculate red mud particulate materials in the Bayer process can be evaluated on the basis of their efficiency to achieve adequate settling velocities and turbidity levels. In this study, three commercially available flocculants are evaluated under typical conditions found in the last washer of a Bayer plant. The different shear levels are produced by using a modified Couette flow system. Great differences are noticed in the performance of the polymers when they are compared at different dosages and at different shear rate levels. The data collected also suggests that conventional cylinder settling tests may not be adequate to measure the performance of certain types of polymers. (author)
Some results and experimental procedures of laboratory are reported in the frame of researches conducted for the development of new nanostructured composite materials. These new materials, which are constituted by an organic phase: the polymer and an inorganic phase: the silicate, are being strongly investigated nowadays so it is expected that they could provide, among other, better electrical insulation properties and flame-delay in electrical and electronic applications. The laboratory experimental work has been developed from two families of polymers, thermoplastics and thermosets and clays silicates providing lamellar type. There are now some preliminary results, such as obtaining thin films of these nanocomposite materials, their complete characterization by X-ray diffraction, scanning microscopy and thermogravimetric analysis, they do well to wait for future research activities. (author)
We demonstrate control and improvement of charge injection in organic electronic devices by utilizing self-assembled monolayers (SAMs) to manipulate the Schottky energy barrier between a metal electrode and the organic electronic material. Hole injection from Cu electrodes into the electroluminescent conjugated polymer poly[2-methoxy,5-(2{sup {prime}}-ethyl-hexyloxy)-1,4-phenylene vinylene] was varied by using two conjugated-thiol based SAMs. The chemically modified electrodes were incorporated in organic diode structures and changes in the metal/polymer Schottky energy barriers and current{endash}voltage characteristics were measured. Decreasing (increasing) the Schottky energy barrier improves (degrades) charge injection into the polymer. {copyright} {ital 1997 American Institute of Physics.}
New technologies are needed to reduce the current high rate of well abandonment. Improved sweep efficiency, reservoir conformance, and permeability modification can have a significant impact on oil recovery processes. Microorganisms can be used to selectively plug high-permeability zones to improve sweep efficiency and impart conformance control. Studies of a promising microbial system for polymer production were conducted to evaluate reservoir conditions in which this system would be effective. Factors which can affect microbial growth and polymer production include salinity, pH, temperature, divalent ions, presence of residual oil, and rock matrix. Flask tests and coreflooding experiments were conducted to optimize and evaluate the effectiveness of this system. Nuclear magnetic resonance imaging (NMRI) was used to visualize microbial polymer production in porous media. Changes in fluid distribution within the pore system ...
In this work, a water-soluble polymer, polyethylenimine (PEI) was used for the simultaneous separation and preconcentration of trace Cu and Mn prior to their determination by flame atomic absorption spectrometry. For this purpose, the sample and the PEI solution were mixed and the metal-bound polymer was precipitated by adding acetone. The precipitate was separated and dissolved in a minimum amounts of water and aspirated into a flame AAS. By increasing the ratio of the volumes of sample to water used in dissolving the precipitate, the analyte elements were concentrated as needed. The sorption is quantitative in the pH ?6. Detection limits were 5.2 ?g/L for Cu and 5.4 ?g/L for Mn. This method is simple, fast and precise.
The emergence of nanoscience has increased the importance of experiments able to probe the very local structure of materials, especially for disordered and heterogeneous systems. This is technologically important; for example, the nanoscale structure of glassy polymers has a direct correlation with their macroscopic physical properties. We have discovered how a local, high frequency dynamic process can be used to monitor and even predict macroscopic behavior in glassy polymers. Polyvinylethylenes vitrified by different chemical and thermodynamic pathways exhibit different densities in the glassy state. We find that the rate and amplitude of a high frequency relaxation mode (the Johari-Goldstein process involving local motion of segments of the chain backbone) can either correlate or anti-correlate with the density. This implies that neither the unoccupied (free) volume nor the configurational entropy governs the local dynamics in any general ...
A stiff skin forms on surface areas of a flat polydimethylsiloxane (PDMS) upon exposure to focused ion beam (FIB) leading to ordered surface wrinkles. By controlling the FIB fluence and area of exposure...Full Text Available
A method for the study of conjugated polyelectrolyte (CPE) photophysics in solution at the single-molecule level is described. Extended observation times of single polymer molecules are enabled by the...Full Text Available
The electric explosion of a conductor being part of an electric cable is studied. It is ascertained that the electric properties of a polymeric dielectric depend nonlinearly on the maintenance of the ultradisperse metal filler. In the course of the numerous heating-cooling processes of an insulator, a streamlining of the structure of a polymeric composite occurs.
Wood Plastic Composite (WPC) was prepared with simul (soft wood, density = 0.4g/cc) and butylmethacrylate (BMA) monomer using 10% methanol as the swelling agent. Effect of additives including (i) multifunctional acrylates such as tripropylene glycol diacrylate (TPGDA), trimethylol propane triacrylate (TMPTA) (ii) oligomer acrylates like the urethane (UA), epoxy (EA) and polyester (PEA) acrylates and (iii) N-vinyl pyrrolidone (NVP) was investigated using 1 to 3 Mrad dose at 0.8 Mrad/h. Synergistic increases in polymer loading yields was achieved in presence of the additives, particularly with the trifunctional acrylate (TMPTA). In addition, acid as well as urea were also used as co-additives and synergistic enhancement in yields of polymer loading were obtained. The synergistic polymer loading by acid addition causes substantial decrease in tensile strength of the composite; but other additives and co-additives increase both ...
Using a series of polycations synthesized by atom transfer radical polymerization (ATRP), we investigate the effects of the polymer charge density and hydrophobicity on salt-induced interdiffusion of polymer layers within polyelectrolyte multilayer (PEM) films. Polycations with two distinct hydrophobicities and various quaternization degrees (QPDMA and QPDEA) were derived from parent polymers of matched molecular weights poly(2-(dimethylamino)ethyl methacrylate) (PDMA) and poly(2-(diethylamino)ethyl methacrylate) (PDEA) by quaternization with either methyl or ethyl sulfate. Multilayers of these polycations with polystyrene sulfonate (PSS) were assembled in low-salt conditions, and annealed in NaCl solutions to induce layer intermixing. As revealed by neutron reflectometry (NR), polycations with lower charge density resulted in a faster decay of film structure with distance from the substrate. Interestingly, when comparing ...
We describe the interactions of two benzimidazole derivatives, astemizole (AST) and lansoprazole (LNS), with anomalous aggregates of tau protein (neurofibrillary tangles). Interestingly, these...Full Text Available
Polymers are required to use in radiation environments as insulation materials. However, they often suffer from tracking failure. There is an increasing demand to evaluate radiation effects on dielectric performance. This paper presents a recurrence plot (RP) approach to analyse surface discharge sequences of gamma-ray irradiated polymer materials based on tracking test. Studying the non-linear characteristics of discharge sequences can assist in understanding the underlying mechanism of the discharge process. Discharge sequences of the test are extended to m-dimensional phase space by using the phase space reconstructed method. As test samples, polybutylene terephthalate (PBT) and polybutylene naphthalate (PBN) were irradiated to 100 kGy and then up to 1 MGy with a dosage rate of 10 kGy h{sup -1} by using a {sup 60}Co gamma source. The tracking tests were carried out according to the test method described in IEC60112. It is found that the RPs ...
In this study, we report the physico-chemical and biological properties of a novel biodegradable composite scaffold made of nano-hydroxyapatite and natural derived polymers of chitosan and carboxymethyl...Full Text Available
Dimethacrylate polymers and composites are seeing increased usage in orthopedics. As these applications require the material to integrate with the surrounding tissues, direct contact cytotoxicity...Full Text Available
Polysaccharides like cellulose and chitosan are known for their filmic properties. This paper concerns the synthesis and the study of chitosan-based polymer electrolytes. A preliminary work concerns the study of glucosamine reactivity. The poly-condensation of chitosan ethers (obtained by reaction with ethylene oxide or propylene oxide) with bifunctional and monofunctional oligo-ethers leads to the formation of thin lattices (10 {mu}m) having excellent mechanical properties. The presence of grafted polyether chains along the polysaccharide skeleton allows to modify the vitreous transition temperature and the molecular disorder of the system. Two type of polymer electrolytes have been synthesized: electrolytes carrying a dissolved alkaline metal salt and ionomers. The analysis of their thermal, dynamical mechanical, nuclear magnetic relaxation, electrical, and electrochemical properties shows that this new class of polymer ...
... Highly-Functional Materials" was launched in JFY1996 under the New Materials field. This project was ... Bio-mimetic materials" (1) Advanced stimuli responsive materials (2) Harmonized molecular materials ...
Kusy,. R. P. and. Corneliussen,. R. D.,. Polym. Eng. Sci.,. 15,. 1975 pp. 107. DeAraujo,. F. T. and. Rostenberg,. H. M.,. Jour. Phys.,. Sec. D,. Appl. ...
Synthetic polypeptide antigens of L amino acids, although bearing repeating sequences, are thymus-dependent (L-TD), whereas the same polymers composed of D amino acids are thymus-independent (D-TI),...Full Text Available
In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the ..beta.. chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.
In the synthesis of the peptidyl-polymer corresponding to the sequence (57-100) of the #beta# chain of human hemoglobin on Teflon with radiationally grafted polystyrene a comparative study was made of different methods of fragment condensation. It was shown that the most effective methods are azide condensation and condensation with the use of complex F.
BackgroundVascular stents are small tubular scaffolds used in the treatment of arterial stenosis (narrowing of the vessel). Most vascular stents are metallic and are deployed either...Full Text Available
Measurements of PEM fuel cell device performance were made with different gas inlet temperatures and relative humidity using a newly-designed test fixture. Significant improvement in device performance was observed when the fuel inlet temperature was increased above the operating temperature of the cell. These measurements were then correlated to a model to describe energy and mass transport processes. Proton exchange membrane (PEM), fuel cells--the focus of this study--use an ion conducting polymer, especially polyperfluorosulfonic acid materials. These polymer materials, when imbibed with water, exhibit solution-like properties, but because the anions are chemically bound to the polymeric structure, the electrolyte is contained. Importantly, product water removal is simplified, as electrolyte dilution is not a concern. However, the proton transport rate is a function of the polymer geometry, which is set, in part, by the ...
Nanoporous materials have become indispensable in many fields ranging from photonics, catalysis and semiconductor processing to biosensor infrastructure. Rapid and energy efficient process fabrication of these materials is, however, nontrivial. In this communication, we describe a simple method for the rapid fabrication of these materials from colloidal dispersions of Polymethyl Silsesquioxane nanoparticles. Nanoparticle-polymer composites above the decomposition temperature of the polymer are examined and the entropic gain experienced by the nanoparticles in this rubric is harnessed to fabricate novel highly porous films composed of nanoparticles. Optically smooth, hydrophobic films with low refractive indices (as low as 1.048) and high surface areas (as high as 1325 m2 g-1) have been achieved with this approach. In this communication we address the behavior of such systems that are both temperature and substrate surface energy dependent. The ...
... of new construction materials; and the behavior of infrastructure materials and structural ... polymers, reinforcing materials, wood and biodegradable structural materials; scale effects from ...
This patent describes a delayed acrylamide containing polymer crosslinker having stability in an aqueous solution at high temperatures. It comprises: a combination of an aldehyde and a salicylic acid derivative selected from salicylamide and acetysalicylic acid.
international vehicles, control centers, and ground support personnel. ... consists of thin membranes made from a polymer-based film and ..... (including airplanes and submarines), environmental monitoring, and control ...... sciences can use it to analyze the birth and death of stars, the formation of solar ...
A 300 W fuel cell power pack has been developed for educational purposes in close collaboration with the Fachhochschule Solothurn Nordwestschweiz. The project was initiated and financed by the Swiss Federal Office of Energy. The outlay and the performance of the power pack are described. (author) 3 figs.
This is a preliminary study on the sound absorption properties of two tropical hardwoods, Light Red Meranti and Ramin, and their wood-polymer composites. Sound absorption is measured using a standing wave apparatus. The samples are of one thickness (7 mm) and cut longitudinally. Wood-polymer composites are made by impregnating the samples with methyl methacrylate which is polymerized in situ through #gamma#-irradiation. Both woods and their composites are better sound absorbers at higher sound frequencies. With partial impregnation, the absorption coefficients are improved upon particularly in the region between 1-3 kHz. (author).
The scattering and recombination processes between two triplet excitons in conjugated polymers are investigated by using a nonadiabatic evolution method, based on an extended Su-Schrieffer-Heeger model including interchain interactions. Due to the interchain coupling, the electron and/or hole in the two triplet excitons can exchange. The results show that the recombination induces the formation of singlet excitons, excited polarons and biexcitons. Moreover, we also find the yields of these products, which can contribute to the emission, increase with the interchain coupling strength, in good agreement with results from experiments.
The resistance of six tropical hardwoods to fungal degradation by two wild-type strains of Phanerochaete chrysosporium Burdsall was investigated using vermiculite burial and wood-block weight loss techniques. Radiation-induced wood-polymer composites (WPC), based on two hardwoods Ramin and Rubberwood with methyl methacrylate, were prepared, and samples were also exposed to the wood-rotting fungus. A significant improvement in resistance to fungal decay was observed in the WPC. Scanning-electron micrographs of the two woods and their composites after fungal degradation are presented and discussed.
The lithium-polymer energy storage technology requires the production of thin films of huge surface. The BT-EdF-CEA consortium has studied the various manufacturing techniques of these films and their assembly. The process was chosen according to its productivity, low expensiveness, ecological impact and energy performances with capacities reaching 40 Ah. This paper explains: the objectives and specifications of the project, the advantage of the consortium and the role of the different partners, the results (coating, dry extrusion and battery element manufacturing techniques), and the electrochemical performances of the elements. (J.S.)
Radiation-initiated polymerization of styrene and acrylic acid in poplar wood were investigated for the preparation of wood-polymer composites. The direct irradiation method was applied to the monomer adsorbed poplar wood specimens. 8000 Ci "6"0Co source at a dose rate of about 0.4 Mrad/h was used. Furthermore the effects of carbon tetrachloride, methanol, dioxane and acrylonitrile on styrene polymerization were investigated and the reaction rates were calculated for each case. The influence of CCl_4 (10%) on acrylic acid polymerization in poplar wood was also determined. (author).
Atmospheric pressure plasma enhanced chemical vapour deposition system is built. The electrical and optical characteristics of the APPECVD system is given. The system is used to deposit conductive polymers and nano composites onto glass and metal surfaces. The morphological, optical, chemical and electrical characteristics of deposited surfaces are investigated using SEM, AFM four probe deposition purposes. The photovoltaic applications of plasma deposited polymers and nonconsumption are compared with deposited with electrochemical methods show different results. The electrical, chemical and morphological structures of the samples will be given.
The removal of Reactive Black 5 dye in an aqueous solution by electrocoagulation (EC) as well as addition of flocculant was investigated. The effect of operational parameters, i.e. current density, treatment time, solution conductivity and polymer dosage, was investigated. Two models, namely the artificial neural network (ANN) and the response surface method (RSM), were used to model the effect of independent variables on percentage of dye removal. The findings of this work showed that current density, treatment time and dosage of polymer had the most significant effect on percentage of dye removal (p0.8). PMID:21411950
Recently, organic semiconducting materials have gained a broad interest due to their potential for organic electronic devices such as organic light emitting diode (OLED), organic photovoltaic devices and organic field-effect transistors (OFETs). Optical properties of organic semiconducting materials are important for practical application. For example, the power conversion efficiency of organic photovoltaic devices is mainly affected by absorption properties of organic materials. Proton irradiation is one of the efficient methods to change the optical properties of organic materials. In this paper, we investigate the changes of optical properties of various polymers using the proton irradiation.
Purpose - This paper aims to describe the technology and applications of nanocomposite materials. Design/methodology/approach - This paper discusses products, applications and technological developments in polymer, ceramic and metal nanocomposites. It concludes with a brief consideration of electronic component applications. Findings - It is shown that polymer nanocomposites and the materials used in their production are commercially available and finding applications in several industries, including automotive, military, food, electronics and leisure, due to their enhanced mechanical, electrical and thermal properties. Ceramic and metallic nanocomposites are at an earlier stage of development and a critical issue to resolve is optimising the dispersion of nanomaterials in the matrices. Pa...
This review begins with an historical account of biomaterials applications followed by a concise description of the phenomena taking place between the living tissues and non-living materials containing them. After describing the requirements for biodegradability and the mechanisms involved, a thorough literature survey of such polymers is presented. In the end a very short review of the work done in this area by the authors in recent years is given, including: the synthesis of a wide variety of biodegradable di-and tri-block copolymers, preparation of microparticles; stealth-and immuno-liposomes; dendrosomes and polymersomes; and some of their applications in drug and gene delivery.
This paper describes the experimental results of accelerated aging tests conducted on three different types of polymer materials. Salt fog chamber tests were used to study the surface degradation modes for all materials. The work presented here was performed using a newly constructed fog chamber system that was able to control both chamber humidity and UV radiation. The changes in the surface morphology, material structure and leakage current were examined to study the influence of environmental humidity.
The in-situ observation of dendritic growth in lithium/polymer electrolyte-LiTFSI/lithium battery cells shows that dendrites grow up with about the same rate as anion migration. Memory effects have been evidenced in cycling experiments and limit the dendrites length. An overall movement of the electrolyte due to variations of electrolyte concentration in the vicinity of the electrodes has been observed too. (J.S.) 13 refs.
Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30 kGy) at a dose rate of 3.5 kGy/h using a {sup 60}Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used.
Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30 kGy) at a dose rate of 3.5 kGy/h using a "6"0Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used.
Wood-plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, using three monomer systems; acrylamide, butylmethacrylate, and styrene, with methanol as the swelling solvent. Polymerization was induced at various radiation doses (10, 20, and 30 kGy) at a dose rate of 3.5 kGy/h using a "6"0Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength have been measured. The polymer loading decreases approximately with increasing density of the wood species used. (author)
Two species of wood, viz. Haldu (Adina Cordifolia) and Jamun (Syzygium Cumini) were vacuum-impregnated with two styrene-based monomer systems and polymerized in situ with gamma radiation from a cobalt-60 source. The electrical conductivity of these specimens was determined at various polymer loadings under dry conditions, after wetting and after wet recovery as per ASTM standards. The water absorption characteristics are also presented. The results are discussed with special reference to the role of water. Potential applications are also discussed. 7 figures.
Polymer composites are used in numerous applications. In spite of this fact, new developments are still under way to explore in other field of application of these materials and to tailor their properties for more extreme condition. A particular emphasis is focused on fillers content is summarized. Some steps towards the functionally graded materials are illustrated. The FT-IR spectroscopic studies revealed the information about curing of epoxy with fillers. It was observed that mechanical properties like tensile strength, hardness etc get enhanced up with filler contents. The effect of the different formulations were investigated and discussed for optimum process condition. (author)
In the framework of the development of new generations of surface ships, the Royal Netherlands Navy is studying the option of the all-electric ship concept. Background is the growing demand of electric power on board of naval ships for various services (including weapons and sensors). Important features of such an all-electric ship concept are decentralized electric energy generation and storage. In such an all-electric ship concept, fuel cells are expected to play an important role in the future, not only for reasons of energy efficiency and low emissions, but also because of their potential military advantages. Especially polymer electrolyte fuel cell systems appear to be very interesting for this application.
The currently available propellants achieve about 95% of the combustion performance which can be expected theoretically at this time, consequently a technological breakthrough concerning new propellants have been demanded. Among high energy substances which are being studied, polymer azide which can continue combustion without relying on the oxidation reaction is a typical high energy substance to be used for a propellant of the next generation. The composite propellant which has polymer azide as fuel component and ammonium nitrate as oxidizer is considered to be the extremely promising propellant, since it provides no combution product which causes the environmental destruction. (6 figs, 4 refs)
Abstract The creation of chirality on Earth and the development of chiral life have been discussed in this highlight. Convincing evidence for the introduction of chirality on Earth is still fragmentary. We believe that by a combination of chiral crystallization and formation of helical polymers with preferred chiral conformational structure is the key to this question. This concept of macromolecular asymmetry has inspired ideas and resulted in possible rules for how chiral life as we know it, could have been introduced. These investigations needed the understanding of the requirements for chiral crystallization, for the stereochemistry of the initial formation of helical polymers, the measurements of optical activity of solids and their coordination with the fundamentals of chirality. Spac...
An apparatus was designed and built for the purpose of exposing samples of solid polymers to varying temperatures, atmospheres and stress levels while quantitatively recording the resulting chemiluminescence. Preliminary data were acquired with this apparatus that show a correlation between an enhanced chemiluminescence signal at a low level of applied stress and a decrease in tensile strength for the most commonly used epoxy resin in high performance fiber composites, TGMDA DDS. The studies with cellular silicone cushions (which are used to accommodate thermal expansion and contraction) have defined the temperature regimes in which accelerated aging tests are valid for extrapolation to ambient temperature. Preliminary data on Kevlar fibers is also discussed.
All-optical envelope detection of a 5 GHz 200 Mbit/s modulated radio frequency signal is achieved using a 650 nm resonant cavity light emitting diode. Error-free transmission is achieved over a 50 m-long link of 1 mm diameter graded index polymer optical fibre (POF). The presented system has potential applications in low cost and low complexity short range wireless and wireline POF-based transmission links.
Thermoplastic encapsulation has been extensively studied at Brookhaven National Laboratory`s (BNL) Environmental and Waste Technology Center (EWTC) as a waste encapsulation technology applicable to a wide range of waste types including radioactive, hazardous and mixed wastes. Encapsulation involves processing thermoplastic and waste materials into a waste form product by heating and mixing both materials into a homogeneous molten mixture. Cooling of the melt results in a solid monolithic waste form in which contaminants have been completely surrounded by a polymer matrix. Heating and mixing requirements for successful waste encapsulation can be met using proven technologies available in various types of commercial equipment. Processing techniques for thermoplastic materials, such as low density polyethylene (LDPE), are well established within the plastics industry. The majority of commercial polymer processing is accomplished using extruders, ...
Ionic conductive materials are of much interest as an electrolyte for solid-state lithium batteries. Poly(alkylene oxide) and lithium salt complex exhibits high ionic conductivity in terms of its high solubility for lithium salts. However, the temperature dependency of its ionic conductivity is quite large and non-linear, the ionic conductivity drops down at low temperature, especially below glass transition temperature of the polymer. Because its ionic conductive mechanism is derived from its segmental motion of polymer main chain. A novel ionic conductive material, poly[2,6-dimethoxy-N-(4-vinylphenyl)benzamide] is synthesized and confirm ionic conductivity even below glass transition temperature. Ionic conductivity of the polymer with lithium ditrifluoromethylsulfonate imide complex shows 10{sup -5}Scm{sup -1} from 0 to 60{sup o}C. Its temperature dependency is linear, namely Arrehnius type dependency. Evaluating from ...
Thermoplastic polymer materials and the compounds made with them are being used more frequently for industrial components and for general use. However, the application of these materials for the production of complex shaped or relatively large pieces is limited, because of the difficulty and cost of making the necessary tool kit for the job. One solution is the use of the welding process. But the safe and reliable union of different thermoplastic material parts is not a simple process, even less so in the case of unions of large components. Welding by microwaves using polymer conductors can help, since the large scale equipment is available, and methods for continuous processes by microwave have been developed, that can be used to weld large and small components. Many thermoplastics (ex. polyethylene) do not absorb, or absorb very little, energy from microwaves. Polymer conductors, however, heavily absorb from microwaves ...
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This report presents geologic considerations that are pertinent to the Remedial Action Plan for Slick Rock mill tailings. Topics covered include regional geology, site geology, geologic stability, and geologic suitability.
The adenovirus fiber knob causes the first step in the interaction of adenovirus with cell membrane receptors. To obtain information on the receptor binding site(s), the interaction of labeled cell...Full Text Available
This report is a summary of the environmental status of the Hanford Site in 1989. It includes descriptions of the Site and its mission, the status of compliance with environmental regulations, planning and activities to accomplish compliance, environmental protection and restoration activities, and environmental monitoring. 97 refs., 67 figs., 14 tabs.
Expedited site characterization (ESC), developed by Argonne National Laboratory, is an interactive, integrated process emphasizing the use of existing data of sufficient quality, multiple complementary characterization methods, and on-site decision making to optimize environmental site investigations. The Argonne ESC is the basis for the provisional ESC standard guide of the ASTM (American Society for Testing and Materials). QuickSite{sup SM} is the implementation package developed by Argonne to facilitate ESC of sites contaminated with hazardous wastes. At various sites, Argonne has successfully implemented QuickSite{sup SM} and demonstrated the technical superiority of the ESC process over traditional methodologies guided by statistics and random-sampling approaches. A key feature in the success of QuickSite{sup SM} ...
Mitochondrial superoxide production is an important source of reactive oxygen species in cells, and may cause or contribute to ageing and the diseases of ageing. Seven major sites of superoxide...Full Text Available
Quantitative determination of Broensted acid site concentrations in calcined H-mordenite and H-ZSM-5 by means of conductometric titration and infrared spectroscopy reveals that the concentration of Broensted acid sites present is lower than would be expected on the basis of the aluminum content. This discrepancy is attributed to dealumination and dehydroxylation processes occurring during calcination. A model is proposed according to which the degree of these processes strongly depends on the concentration of vicinal aluminum T sites in the zeolite: Broensted acid sites associated with these T sites are lost, and the remaining Broensted acidity is related to the concentration of the (remaining) isolated aluminum T sites. This model quantitatively correlates the experimentally determined concentration of Broensted acid sites with the ...
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The geology and hydrology of the reference New Production Reactor (NPR) site at Savannah River Site (SRS) have been summarized using the available information from the NPR site and areas adjacent to the site, particularly the away from reactor spent fuel storage site (AFR site). Lithologic and geophysical logs from wells drilled near the NPR site do not indicate any faults in the upper several hundred feet of the Coastal Plain sediments. However, the Pen Branch Fault is located about 1 mile south of the site and extends into the upper 100 ft of the Coastal Plain sequence. Subsurface voids, resulting from the dissolution of calcareous portions of the sediments, may be present within 200 ft of the surface at the NPR site. The water table is located within 30 to 70 ft of the surface. The NPR ...
A simple approach to controlling the loading percentage and size of zero-valent iron nanoparticles (ZVI NPs) immobilized within polyacrylic acid (PAA)/polyvinyl alcohol (PVA) nanofibrous mats for dye remediation applications is described. A functional "nanoreactor" comprised by electrospun PAA/PVA nanofibers served to bind ferric ions with the carboxyl groups of PAA, prior to their reduction to ZVI NPs. The resulting ZVI NP-immobilized hybrid polymer nanofibers were characterized using scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The morphology of the polymer nanofibers exhibited no appreciable change even after eight cycles of ferric ion binding/reduction, and the loading percentage and size of the ZVI NPs were controlled simply by varying the number of ferric ion binding/reduction cycles. Dye remediation experiments revealed that the decoloration effect of ZVI NPs immobilized within the ...
The chemical fixation of tritium in stearic acid followed by embedding the tritiated stearic acid into an epoxy resin proved to be a good method for permanent waste disposal of tritium gas. Tc-126 and Tc-136 hardener were used for this purpose. The polymerization temperature of the polymer products was found to be highly decreased by adding stearic acid and slightly decreased by adding stearic acid or by raising the temperature of the leachant medium and slightly decreased by irradiation. On the other hand, small improvement in the compressive strength of the polymer products was achieved by adding silica powder. The polymer product showed high flame points above 573 K although it contains stearic acid. DTA and TG analysis indicate that the thermal stability of polymer products containing stearic acid and silica powder is better than samples containing only stearic acid. Stearic acid was found to ...
High energy muon colliders, such as the TeV-scale conceptual designs now being considered, are found to produce enough high energy neutrinos to constitute a potentially serious off-site radiation hazard in the neighbourhood of the accelerator site. A general characterization of this radiation hazard is given, followed by an order-of-magnitude calculation for the off-site annual radiation dose and a discussion of accelerator design and site selection strategies to minimize the radiation hazard.
The Formerly Utilized Sites Remedial Action Program (FUSRAP) is to evaluate the radiological conditions at former MED-US AEC sites. Purpose of the Ocean FUSRAP program is to assess the feasibility of ocean disposal of FUSRAP waste which contains trace natural radioactive materials. This paper presents soil characterization information on the Middlesex, NJ, Sampling Plant site, and reports preliminary ocean dispersion calculations. (DLC)
The objectives of this project to interface the site-specific real-time radiological dose assessment system FADAS(Following Accident Dose Assessment System) to CARE. In this study, the results of the field tracer experiments conducted on the Younggwang site have been analysed. And the experimental procedure on Ulchin site has been introduced. The environmental characteristics on Ulchin and Wolsung has been investigated.
After a presentation of methods and tools for the basic and extensive characterization of polluted sites and the study of evolution and transfer of current organic pollutants in the ground, the example of the rehabilitation of an old Rhone-Poulenc site (at Chauny, France) polluted with metals and arsenic, is described: soil and aquifer diagnosis, risk analysis and determination of migration schemes
Site occupancies in three C15-structured AB{sub 2}(X) Laves phases have been determined by Atom Location by CHanneling Enhanced MIcroanalysis (ALCHEMI). In NbCr{sub 2}(V), the results were consistent with exclusive site occupancies of Nb for the A sublattice and Cr and V for the B sublattice. The B-site occupancy of V is not expected from atom size effects alone. In NbCr{sub 2}(Ti), the results were consistent with Ti partitioning mostly to the A sites with some anti-site defects likely. In HfV{sub 2}(Nb), the results were consistent with Nb partitioning between the A and B sites. The results of the ALCHEMI analyses of these ternary C15 Laves phase materials will be discussed with respect to previously determined phase diagrams and first-principles total energy and electronic structure calculations.
Data from natural runoff plots at two experimental sites in northern Iraq were used to predict soil erodibility in this semiarid region. The first site has a mean seasonal rainfall of about 400mm with the plots situated on 40% uniform slope; the soil at the site has a loam texture and belongs to the Xerorthent suborder; it has 46% of gravel by weight in its surface layer. The second site has a mean seasonal rainfall of more than 900mm with the plot situated on 17% uniform slope; the soil at the site is silty clay and belongs to the Calcixeroll suborder. At both sites, soil loss and runoff measurements were collected for two rainfall seasons. Results from both experimental sites showed that storm-to-storm variation in soil erodibility is high reflecting the importance of long term measureme...
This report provides an overview of the scope and status of the US Department of Energy (DOE`s) Salt Repository Project (SRP) at the time when the project was terminated by the Nuclear Waste Policy Amendments Act of 1987. The report reviews the 10-year program of siting a geologic repository for high-level nuclear waste in rock salt formations. Its purpose is to aid persons interested in the information developed during the course of this effort. Each area is briefly described and the major items of information are noted. This report, the three salt Environmental Assessments, and the Site Characterization Plan are the suggested starting points for any search of the literature and information developed by the program participants. Prior to termination, DOE was preparing to characterize three candidate sites for the first mined geologic repository for the permanent disposal of high-level nuclear waste. The ...
Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials ...
Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials ...
The surface coverage of amorphous silica gels used in the synthesis of silica polyamine composites has been investigated by 29Si NMR. By diluting the polyamine anchor silane, chloropropyl trichlorosilane, with methyl trichlorosilane it was found that surface coverage could be markedly improved for a range of amine polymers after grafting to the silica surface. The commensurate decrease in the number of anchor points and increase in the number of free amines results in an increase in metal capacity and/or an improvement in capture kinetics. Solid state CPMAS-13C NMR has been employed to investigate the structure and metal ion binding of a series of these composite materials. It is reported that the highly branched polymer, poly(ethyleneimine) (PEI) exhibits much broader 13C NMR resonances than the linear polymers poly(allylamine) (PAA) and poly(vinylamine) (PVA). These results are understood in terms of the low energy ...
Poly(methyl methacrylate), PMMA, Acrigel, a Brazilian polymer, is used in the manufacture of medical supplies sterelizable by ionizing radiation. However, when PMMA is gamma-irradiated it undergoes main chain scissions, which promote molecular degradation causing reduction in its mechanical properties. Therefore, radiolytic of PMMA is important for it to become commercially radiosterizable. In this work some commercial additives, originally used in photo-and thermo-oxidate stabilization of polymers, were tested. Only two additives, type HALS (Hindered Amine Light Stabilizer), denoted Scavenger, showed a good protective quality. The investigation of radiation-induced main scissions was carried out by viscosimetric method. The most effective additive, added to the polymer system at 0.3 w/w%, promotes a great molecular radioprotection of 93%. That means a reduction of G-value (scissions/100 eV) from 0.611 to 0.053. In ...
Selected local woods and their wood-polymer combinations or composites (WPC) were tested for their thermal conductivity and their fire resistance. WPC were prepared by polymerizing monomers ''in situ'' in oven dried woods by gamma radiation. The monomers included acrylonitrile (AN), 60% styrene-40% acrylonitrile (STAN), methyl methacrylate (MMA), 95% methyl methacrylate-5% dioxane (MD), and vinylidene chloride (VDC). A reduction in thermal conductivity was exhibited by all the composites prepared. W-PAN showed the greatest reduction in thermal conductivity and W-PSTAN in general showed the least. An explanation is suggested for this behaviour. The polymers PMMA and PMD were found to enhance flammability of the woods while PVDC, PAN, and PSTAN imparted fire resistance to the woods. Of the six local woods studied, Ramin-and-Keruing-polymer composites showed the highest flammable tendencies ...
The ink jet printing technology is a relatively novel technique in development of organic electronic devices. The technique consists of working out depositions of organic layers by a piezo-based ink jet printer. In this work polymer conducting films deposited by ink jet printing technique on different plastic substrates has been demonstrated. The poly(3,4-ethylenedioxythiofene)/poly(4-styrenesulfonate) [PEDOT/PSS] and glycerol-modified PEDOT/PSS [G-PEDOT/PSS] were used like conducting inks to be applied on polyester and polyethylene terephthalate (PET) substrates. By means of the change of substrate associated to the deposition number or type of polymer ink used for printing of the conducting films, the sheet resistance can be modified. Such a behavior suggests that plastic substrate fulfills an important role for the changing of sheet resistance of the PEDOT/PSS and G-PEDOT/PSS films made by ink jet printing technique. Films obtained from this ...
Samples of ultra-high molecular weight polyethylene (UHMWPE) and nylon 66, of grades suitable for use in medical prostheses, were subjected to irradiation using a /sup 60/Co source. The effects of a 10 Mrad dose on percentage crystallinity, tensile behaviour and dynamic mechanical response were established 3 days after irradiation at intervals over a one year period. Crystallinity in UHMWPE was found to increase progressively during this period with consequent changes in mechanical behaviour. It is proposed that the observed ageing process arises from the breakdown of metastable groups in the polymer, which are formed on irradiation, with consequent release of long inter-lamella tie chains. This removes an inhibition to crystal perfection processes, which can occur at room temperature in polyethylene. Infra-red spectroscopic evidence supports the proposal that the metastable species is peroxy or hydroperoxy and that this decomposes on ageing to a carbonyl group, ...
Wood plastic composites (WPC) have been prepared with five low-grade woods, native to Syria, and with Okoume (aucoumea klaineana pierre) imported to Syria in large quantities. Three monomer systems; acrylamide, butylmethacrylate, and styrene were used. polymerization was induced at various radiation doses (10, 20, and 30 kGy) to study the role of radiation doses using a "6"0Co gamma radiation source. Some physical properties of WPC, namely polymer loading and compression strength or tensile strength of the obtained wood polymer composites (WPC) were studied. The effect of the additives, sulfuric acid (H"+), N-vinyl pyrrolidone (NVP), trimethyolpropane triacrylate (TMPTA), urea (U), lithium nitrate (LiNo_3), copper sulfate (CuSO_4) and co-additives on monomer system polymerization were also investigated. Methanol, water and water/methanol mixtures were used as the swelling agents. In general, the use of additives and co-additives brought about ...
Objectives1. To develop new photoactive materials and fabricate demonstration QD (quantum dot) solar cells. This will be achieved by:~%~1.1. Materials preparation and characterisation of QD/polymer systems~%~1.2. Optimising structures of QDs, nanorods and polymer for quantum yield and charge transfer~%~1.3 Fabricating demonstration QD/polymer solar cells and measuring power conversion efficiencies~%~2. To demonstrate multiexciton generation (MEG) and harvesting within nanostructured QDs. This will involv [continued...]DescriptionWidespread implementation of photovoltaic electricity to meet changing energy demands requires a step-change in the cost of photovoltaic power. This proposal assembles a consortium of chemists, physicists, materials scientists and electrical engineers from The University of Manchester and Imperial College London to address this need through the development of new low-cost, high-efficiency, ...
Functionalizing nanoparticle surfaces is essential for achieving homogeneous dispersions of monodisperse particles in polymer nanocomposites for successful utilization in engineering applications. Functionalization reduces the surface energy of the nanoparticles, thereby limiting the tendency to agglomerate. Moreover, reactive groups on the surface can also participate in the polymerization, creating covalent bonds between the inorganic and organic phases. In this paper, a fluidized bed inductively coupled plasma (FB-ICP) reactor is used to break apart the agglomerates and functionalize commercial TiO2 nanoparticle powders in a batch of several grams. The fluidized bed could be implemented into a continuous flow reactor, potentially making this a viable method to treat larger quantities of commercial powders. The particles are treated with acrylic acid (AA) and tetraethylorthosilicate (TEOS) plasma and the functionalized particles were collected separately from ...
The confocal Raman micro-spectroscopy has been used for the study of a Lithium/polymer electrolyte-LiTFSI/V{sub 2}O{sub 5} type battery in which the polymer electrolyte thickness is of about 80 {mu}m. The analysis is performed on the side of the battery thanks to a specially designed cell which preserves all the characteristics of the real system. The analysis is performed on 20 points aligned between the anode and the cathode and with a depth of several tenth of {mu}m. The analysis of data obtained during charging/output cycles allows to evaluate the gradients of salt concentration inside the electrolyte, the pollutions of LiOH, Li{sub 2}CO{sub 3}, Li{sub 2}O and Li{sub 3}N -type at the lithium interface, but also the structural modifications of the cathode material. The in-situ study of concentration gradients inside the electrolyte is of prime importance for the understanding of dendrites growth. (J.S.) 11 refs.
For the purpose of proposing it to ISO, the R and D were conducted of a new evaluation method of thermal properties of polymer materials. The FY 1999 results were summarized. In this fiscal year, the development of the ac Joule heating equipment was proceeded with based on the study at the technical committee, and the measuring device was installed. In the comparative measurement with conventional methods, study was proceeded with of the laser flash method, AC calorimetry method and specific heat measurement. In the technical survey, the developmental state of the ac method, especially, was examined as a testing method of thermal properties of polymer materials. It is in the stage of the basic research by keyword selection, and the search for literature is to be made in full scale. As to the needs in the industrial circle, as a result of the questionnaire survey made, it was found out that there were a wide variety of the needs for ...
We show the existence of global-in-time weak solutions to a general class of coupled FENE-type bead-spring chain models that arise from the kinetic theory of dilute solutions of polymeric liquids with noninteracting polymer chains. The class of models involves the unsteady incompressible Navier-Stokes equations in a bounded domain in two or three space dimensions for the velocity and the pressure of the fluid, with an elastic extra-stress tensor appearing on the right-hand side in the momentum equation. The extra-stress tensor stems from the random movement of the polymer chains and is defined by the Kramers expression through the associated probability density function that satisfies a Fokker-Planck-type parabolic equation, a crucial feature of which is the presence of a center-of-mass diffusion term. We require no structural assumptions on the drag term in the Fokker-Planck equation; in particular, the drag term need not be corotational. With ...
Decommissioning of radiological and nuclear installations is for this century the new challenge. One of the performance criteria is the reduction of total quantities of radioactive materials (liquid or solid) arising from dismantling and decontamination of radiological and nuclear installations. In this work we present a new application of the water soluble polymers used as: - flocculation agents in treatment and conditioning process within the management of radioactive liquid materials; - strippable coatings on solid materials based on the water soluble polymers. The parameters of water soluble polymers made in our Institute by radiation processing have been analysed, namely the molecular average weight, composition, and efficiency of utilization of these polymeric materials as well as the content of ash, additives, decontamination factor, consumption per surfaces/liter, corrosion aspects, compatibility with various ...
Different experimental measurements (Theology, granulometry, XRD) were carried out in order to study the main properties of bentonite suspensions in presence of anionic additives at different concentrations. These additives are: Sodium Dodecyl Sulfate (SDS) as surfactant, a flexible polymer (Sodium Carboxy Methyl Cellulose, CMC) and a semi-rigid polymer (Xanthan gum). It has been shown that the structural nature of anionic additive influences directly the mixtures viscoelastic and flow behavior. The steric effect of the surfactant modifies the Face-Edge interactions and yields changes of the mixtures rheological behavior at low deformation rates. Polymers act by coating each clay particle and prevent their agglomeration. Therefore, bentonite has no direct effect on the rheological behavior of the mixtures: the additives are responsible for the mechanisms of de-structuration and structure reorganization as well as the ...
The fundamental mechanisms underlying the chemical degradation of polymers can change as a function of environmental stress level. When this occurs, it greatly complicates any attempt to use accelerated tests for predicting long-term material degradation behaviors. Understanding how degradation mechanisms can change at different stress levels facilitates both the design and the interpretation of aging tests. Oxidative degradation is a predominant mechanism for many polymers exposed to a variety of different environments in the presence of air, and there are two mechanistic considerations which are widely applicable to material oxidation. One involves a physical process, oxygen diffusion, as a rate-limiting step. This mechanism can predominate at high stress levels. The second is a chemical process, the time-dependent decomposition of peroxide species. This leads to chain branching and can become a rate-controlling factor at lower stress levels ...
Theoretical and experimental studies have been carried out on the combustion of azide polymers used as a binder in high-energy propellants. AMMO (3-azidemethyl-3`-methyloxetane) is one of the energetic azide polymers which contain N3 groups in their molecular structures. EDNA (ethylenedinitramine) is a linear nitramine which has modest properties in the flame temperature and the molecular weight of burned gases as compared with HMX (cyclotetramethylenetetranitramine) and NQ (nitroguanidine). In this study, the burning rate characteristics of azide/nitramine propellants were investigated in order to gain a wide spectrum of burning rate. As a result, the burning rate of AMMO/EDNA propellant is higher than that of AMMO/HMX propellant and the pressure exponent of AMMO/EDNA propellant is lower than that of AMMO/HMX propellant. Both AMMO/EDNA and AMMO/HMX propellants exhibited the same combustion wave structure as inert ...
Comprehensive investigation has been made into the application of the polymerization hardening by radiation, particularly electron beam, to the composites of polymers and other materials. The report is divided into four parts, namely 1) characteristics and problems of the reaction of curing by radiation polymerization, 2) improvement of the bonding capability of high molecular weight materials, 3) bonding by radiation, and 4) composites made by the impregnation and polymerization hardening of monomers. The first part includes the effects of dose rate, temperature rise during the hardening, the peculiarity of electron beam irradiation at high dose rate, reaction environment and additive effects. Main conclusions are as follows: caution must be taken to the amount of residual double bonds because they affect the quality of hardened polymers; the polymerization hardening reaction at high dose rate cannot be analogized by that at low dose rate; and ...
The physical properties of polymer blends consisting of one or more crystallizable components are affected by the microstructure of these materials. In particular, the degree of crystallinity can be influenced by processing parameters, and the crystallinity, as well as the phase distribution, may vary as a function of depth through an injection molded part Conventional x-ray diffraction techniques can provide information regarding both phase composition and degree of crystallinity, but, because of the relative transparency of these materials to wavelengths generally available in the laboratory, these techniques provide information representative of only the bulk. By employing parallel beam optics at varying grazing incidence angles, the x-ray sampling depth can be varied without loss of resolution. This technique can be used to vary the effective analysis depth from the top several hundred angstroms for low razing incidence to centimeters for transmission ...
The physical properties of polymer blends consisting of one or more crystallizable components are affected by the microstructure of these materials. In particular, the degree of crystallinity can be influenced by processing parameters, and the crystallinity, as well as the phase distribution, may vary as a function of depth through an injection molded part Conventional x-ray diffraction techniques can provide information regarding both phase composition and degree of crystallinity, but, because of the relative transparency of these materials to wavelengths generally available in the laboratory, these techniques provide information representative of only the bulk. By employing parallel beam optics at varying grazing incidence angles, the x-ray sampling depth can be varied without loss of resolution. This technique can be used to vary the effective analysis depth from the top several hundred angstroms for low razing incidence to centimeters for transmission ...
A range of additives has been developed for enhancing grafting yields in a variety of systems initiated by ionizing radiation. Cellulose has been adopted as the predominant naturally occurring model backbone polymer in these studies because of its structural relationship to wood which is the reference substrate for the work reported in the related second part of this paper concerning composites. Some experiments have been performed with the other major naturally occurring polymer, wool. For comparison purposes with synthetic materials, some studies have also been performed with polypropylene as trunk polymer. Styrene has been used as a predominant monomer in grafting with some experiments utilizing the acrulates like methyl methacrylate. The role of solvent in grafting has been evaluated. UV has been used as initiator to replace ionizing radiation for certain experiments. The additives used were mineral acids, lithium ...
We propose and demonstrate a facile room-temperature synthetic method for obtaining water-soluble magnetic Fe3O4 nanoparticles (NPs) by combining the in situ synthesis and decomposition of a magnetic polymer hydrogel. The Fe3O4 NPs with average diameters of 6.3-8.3nm were synthesized in a cross-linked polyacrylamide (PAAm) hydrogel by coprecipitating iron ions. The decomposition of the magnetic polymer hydrogel by an aqueous solution of sodium hydroxide led to the transfer of Fe3O4 NPs into the aqueous medium. The NPs can be dispersed stably in water for more than three months. The Fe3O4 NPs were characterized by X-ray photoelectron spectra (XPS), X-ray powder diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR). The saturation magn...
The immune system modulates many key biological processes in humans. However, the exact role of the immune system in particle-associated periprosthetic osteolysis is controversial. Human tissue retrieval studies, in vivo and in vitro experiments suggest that the immune response to polymer particles is non-specific and macrophage-mediated. Lymphocytes may modulate this response. However direct lymphocyte activation by polymer particle-protein complexes seems unlikely. However, metallic byproducts may complex with serum proteins and lead to a Type IV, lymphocyte-mediated immune reaction. In predisposed individuals, this reaction may rarely lead to persistent painful joint effusions, necessitating debridement and excision of the bearing surfaces of the prosthesis. In these patients, retrieved...
In this program, contemporary solidification agents are being investigated relative to their applications to major fuel cycle and non-fuel cycle low-level waste (LLW) streams. Work is being conducted to determine the range of conditions under which these solidification agents can be applied to specific LLW streams. These studies are directed primarily towards defining operating parameters for both improved solidification of problem wastes and solidification of new LLW streams generated from advanced volume reduction technologies. Work is being conducted to measure relevant waste form properties. These data will be compiled and evaluated to demonstrate compliance with waste form performance and shallow land burial acceptance criteria and transportation requirements (both as they exist and as they are modified with time). 6 tables.
Utilization of microwaves for heating purposes began in the 1940`s. This new form of energy transfer offers many distinct advantages over conventional heating, such as volumetric, fast, direct, selective, instantaneous, and controllable heating. Studies of microwave processing of polymeric materials in the early 1960`s led to a successful industrial application in the rubber industry. Since the mid-1980`s, there has been a great deal of interest in microwave processing of polymeric materials. Technical issues, such as temperature uniformity and control of thermal runaway during processing, were investigated and many successful laboratory scale results were obtained from both fundamental and processing studies. This paper presents a historical perspective of microwave heating in the processing of polymer composites and discusses possible future directions for technology commercialization.
Polymer insulating materials used in radioactive environments are subjected to a risk of surface degradation caused by tracking. The tracking behavior becomes more complex with the presence of magnetic field. This paper presents investigation of tracking failure of gamma-ray irradiated polybutylene naphthalate (PBN) and polybutylene terephthalate (PBT) under magnetic field. The samples were irradiated in air up to 100 kGy and then up to 1000 kGy with dose rate of 10 kGy/h by using a 60Co gamma-source. Magnetic field Formula Not Shown with flux density of 250 mT was assembled perpendicularly to electric field Formula Not Shown , which gave rise to relative angle between Formula Not Shown and surface normal vector Formula Not Shown of 0degree, 90degree and 180degree, respectively. The experi...
Abstract Thermomechanical behavior of membranes based on blends of poly(vinyl alcohol) (PVA) with different weight percentage (wt %) of glycerol has been studied. Solid-state PVA/Glycerol polymer membranes were prepared by a solution casting method. The films were studied for thermal characteristics by differential scanning calorimetry (DSC) and thermogravimetric analysis and for the mechanical properties including hardness and modulus by nanoindentation method. The dispersion of glycerol within the polymer matrix was examined using scanning electron microscopy. Fourier transform infrared spectroscopy was used to confirm the formation of hydrogen bonding between the plasticizer and PVA in their blends and also to provide information on compatibility and physical interactions between the gl...
In the Peruvian natural forest there are several kind of woods, some of those are not of commercial interest, because have not resistance at termites and wet, are too soft, or can not be well finished, in the others. The present work is devoted to improvement of the physical properties of wood, such as hardness, traction, wet resistance, etc., by means of the generation of a composite wood-polymers cured by using gamma irradiation. The main objective is to establish the main parameters for the polymerization process (economic technical aspect) that decrease the amount of water absorption, in consequence the volumetric variation of Catahua, Mohena and Capirona woods. Gamma irradiation also provides good protection against the biological agents. In consequence, these woods increase its intrinsic and economic values. (author)
In this work it is made a study of the structure and electric properties of chlorate polyethylene (PE-CI) with double and simple bonds obtained by continuous plasma with resistive coupling to 13.5 MHz. The synthesis conditions are power between 10 and 14 W and pressure of (6-7) x 10{sup -2} Torr. The synthesized PE-Cl in that way is soluble in acetone what indicates that probably is formed of short chains and not it shows the generalized inter crossing that is presented in some syntheses by plasma and that it can degrade the electric properties of these polymers. The IR and XPS analysis show the vibration of the C-C, C=C and C-CI bonds. The morphology of the polymer after being dissolved shows a compact and flat configuration. The electric conductivity has an approximately lineal behavior in an interval of 35 to 90% of relative humidity. (Author)
This paper deals with the preparation and characterization of polyaniline/TiO{sub 2} composite by XRD, UV-VIS spectra, TGA/DTA and FTIR. The composite is used as a cathode material for rechargeable battery comprising of zinc container as the anode, cellulose acetate as the separator and polyvinyl sulfate and carboxy methyl cellulose as the solid polymer electrolytes (SPE). By using the PAn/TiO{sub 2} composite as the cathode material, the cylindrical AA type rechargeable battery was fabricated and the following output was observed. The open circuit voltage (OCV) is 1.4 V and current is 250 mA to 1.0 A, 50 recharge cycles, power density is 350 A h/kg and power efficiency is 70%.
Coordination of CoCl2 solutions to the silica polyamine composite, WP-1, made with the branched polymer polyethylenimine (PEI) shows irreversible binding resulting from surface oxidation of the Co2+-Co3+. This is not the case for the silica polyamine composite BP-1 made with the linear polymer polyallylamine where reversible binding and no oxidation is observed. These observations suggested that oxidation of the cobalt was related to the greater coordination number available with the branched polyamine relative to the linear polyamine. A study of the kinetics of cobalt binding to WP-1 indicated initial loading of Co2+ at relatively low coordination number followed by desorption of Co2+ leading to oxidation and irreversible binding. Exclusion of oxygen from the composite-cobalt solution mix...
The use of POE solid polymer electrolytes in negative lithium electrode batteries allows to reach energy density values close to 150 Wh/kg. The functioning of Li/POE/V{sub 2}O{sub 5} elements has been studied on small capacity elementary cells (about 26 mAh) and the results obtained were confirmed using coiled elements of 1.4 to 1.8 Ah capacity. This work has been carried out for Bollore Technologies (BT) and Electricite de France (EdF) companies. (J.S.)
Summary: The surface coverage of amorphous silica gels used in the synthesis of silica polyamine composites has been investigated by 29Si NMR. By diluting the polyamine anchor silane, chloropropyl trichlorosilane, with methyl trichlorosilane it was found that surface coverage could be markedly improved for a range of amine polymers after grafting to the silica surface. The commensurate decrease in the number of anchor points and increase in the number of free amines results in an increase in metal capacity and/or an improvement in capture kinetics. Solid state CPMAS-13C NMR has been employed to investigate the structure and metal ion binding of a series of these composite materials. It is reported that the highly branched polymer, poly(ethyleneimine) (PEI) exhibits much broader 13C NMR res...
Very important performances in the practical use of solid propellants are combustion and physical properties. Among the present solid propellants, composite propellants used ammonium perchlorate (AP) as oxidizers are adopted widely now due to these excellent performances. Recently, a combination of ammonium nitrates (AN) as oxidizers and azido polymers as binders in expected as the propellants which control decrease of combustion properties and satisfy unsensitivity. However, in order to use these azido polymers/AN propellants in practice, further, it is necessary to improve the specific impulse and the burning rate. In this report, aiming to improve the combustion properties of BAMO/NMMO/AN propellants, the sensitivity and the combustion properties of propellants added high energetic plasticizers in binders, further, displaced a part of AN to cyclotetramethylenetetranitramine (HMX) and double based base-grain (BG) are described. 8 refs., 3 ...
An effective rehabilitation strategy is proposed to enhance the strength and stiffness of the beam-column joint in this study. An analytical model is proposed to predict the column shear of the joints strengthened with carbon fiber reinforced polymer (CFRP). Three full scale interior beam-column joints, including two specimens strengthened with CFRP and one prototype specimen, are tested in this study. The specimens are designed to represent the pre-seismic code design construction in which there is no transverse reinforcement. A new optical non-contact technique, digital image correlation (DIC), which can measure the full strain field of specimen, is used to measure and observe the full strain field of the joint. The experimental results show that the beam-column joints strengthened with ...
The first part of the study contains a literature compilation of more than 50 original publications reporting the radiation induced effects in 17 different high polymer materials and glass which are relevant in the manufacturing of medical devices or packing materials. The results collected demonstrate that high energy radiation, i.e. gamma- or X-rays, causes various physical and chemical alterations in high polymer materials. A detailed summary and discussion of the results of the original publications is not included in the present report, it will be presented in the second part of the study. Furthermore, the second part of the study will refer to the aspect of wholesomeness of irradiated medical devices or packing materials in a more general manner of representation. (orig.).
Abstract A one step method was used to prepare stable aqueous nanocomposite dispersions based on cellulose whiskers extracted from the rachis of the date palm tree and a poly(styrene co 2 ethyl hexylacrylate) copolymer via miniemulsion polymerization. A reactive silane, i.e., methacryloxypropyl triethoxysilane was added to stabilize the dispersion and favor the anchoring of the whiskers on polymer particles. Dynamic light scattering was used to study the effect of the silane and whiskers contents on the average particle size of the polymer. Nanocomposites materials were prepared from these dispersions using a casting/evaporation method. The effect of the silane and whiskers contents on the thermal and mechanical properties were studied using differential scanning calorimetry and dynamic me...
Effects of #gamma#-irradiation on synthetic polymers and paper used as packaging materials for irradiated food have been studied by NMR. Polystyrene, polybutadiene and some copolymers were studied before and after the #gamma#-irradiation treatment and in the presence or absence of antioxidants and stabilisers. In the absence of additives, the effect of #gamma#-irradiation on polystyrene is negligible even irradiating at high doses. In turn, the role of antioxidants and stabilisers is crucial in polybutadiene and butadiene-containing copolymers. Wood pulp paper was also studied by NMR. Preliminary measurements on #gamma#-irradiated wood pulp sheets show a shortening in the T_2 relaxation time component due to the bound water, i.e. some of the bound water is lost. (author)
This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of ...
Aluminium AA5182 coupons covered by a polyaniline film in the emeraldine base (EB) form showed increasing corrosion potential and decreasing corrosion current as a function of the thickness of the polymer layer. The cathodic reaction was proved not limited by diffusion of species inside the electrolyte solution and oxygen had no effect on the electrochemical behaviour of the coated samples. An EB coating on indium tin oxide conducting layer appeared slightly electroactive in neutral media. The IR spectra of aluminium coated samples, before and after heating in argon atmosphere, confirmed a redox reaction between the polymer film and the metal. This galvanic coupling can explain the good protective behaviour of emeraldine base against corrosion of aluminium.
This document reproduces the final project of David San Fabian Ayuso, presented on May 26, 2005, for the obtention of the engineer degree of the Carlos III University of Madrid. A single-phase, isothermal model, including both electron and proton transport, is introduced for the simulation of polymer electrolyte fuel cells (PEM). The model is implemented in the commercial code Fluent 6.0, through the use of UDFs (User Defined Functions). In order to validate the model, a single canal of a PEM monocell is simulated in three dimensions. The obtained result are qualitatively satisfactory. It is observed that it is not essential to solve the current collectors when a monocell is considered (and not a stack). in the present study, the number of nodes is the computational grid appears to be too low in the membrane zone in order to make a complete validation of the model. (Author) 20 refs.
Contents: recent trend of battery technologies; alkaline manganese battery with no mercury addition; high capacity zinc-air battery series for hearing aids; characteristics of vanadium-niobium-lithium rechargeable battery; high-energy density lithium-ion rechargeable battery; lithium polymer rechargeable battery: polymer gel electrolyte and electrode; high-capacity ni-cd battery sm120; high-capacity nickel-metal hydride battery; sealed-type batteries for electric vehicles; high-temperature-durable calcium-type battery for automobiles; sealed lead acid batteries for upss; solar cell power unit; solid oxide fuel cell (1); battery management system.
We summarize recent developments in x-ray microscopy of polymers by focusing on the characterization of organic electronic devices. The quantitative compositions of model polymer blends have been mapped at a resolution of {approx}35 nm. Since it could be inferred that these devices have structures smaller than 35 nm, quantitative compositional mapping at length scales below the present resolution limit of x-ray microscopy is required. Organic devices thus serve to both highlight the success of NEXAFS microscopy to date, but to also outline the very real need for higher spatial resolution. New approaches to create improved optics or different acquisition modalities are required if x-ray microscopy is to make sustained contributions to such an important area of research as organic devices.
In Polymer Electrolyte Fuel Cell (PEFC) technology the reducing of volume and mass of the fuel cell stack and the improvement of catalyst utilization are of great interest. These parameters affect applicability and system cost. In this work we present an alternative way for reducing the stack volume by combining gas distribution and catalytic active area in one plate. Micro machined glassy carbon electrodes serve as support material for the platinum catalyst, as well as gas distributor at the same time. A comparison of these electrodes with conventional platinum-black gas diffusion electrodes under fuel cell conditions shows that the new system is a promising electrode type for enhanced power density and catalyst utilization. (author) 3 figs., 5 refs.
An investigation was made of the accumulation of laser damage to transparent polymers irradiated with nanosecond pulses from neodymium and ruby lasers. The damage was investigated by the method of scattering and luminescence in the visible and near ultraviolet parts of the spectrum. It was established that there were two stages in laser damage by repeated irradiation with pulses of intensity below the single-shot damage threshold. An absorbing defect evolved during the first stage in such a way as to create a thermal instability in the surrounding matrix. During the second stage this thermal instability caused spatial growth of laser damage because of propagation of an ionization-inducing absorption wave with a front traveling at the rate governed by the electron component of the thermal conductivity.
The results of following the oxidative degradation of a plastic-bonded explosive (PBX 9501) are reported. Into over 1100 sealed containers were placed samples of PBX 9501 and combinations of its components and aged at relatively low temperatures to induce oxidative degradation of the samples. One of the components of the explosive is a poly(ester urethane) polymer and the oxidative degradation of the samples were following by measuring the molecular weight change of the polymer by gel permeation chromatography (coupled with both differential refractive index and multiangle laser light scattering detectors). Multiple temperatures between 40 and 64 degreeC were used to accelerate the aging of the samples. Interesting induction period behavior, along with both molecular weight increasing (cro...
Single stage separation factors ..cap alpha.. have been determined for /sup 6/Li and /sup 7/Li between lithium ions in methanol and complexed ions with a cryptand (2 sub(B), 2, 1) polymer. The /sup 6/Li was concentrated in the cryptand. The separation factors were compared with the values of other chemical exchange systems. The maximum enrichment factor obtained was epsilon = 0.047 +- 0.002. The figure is one of the greatest in the chemical exchange reactions without valence change and almost 10 times larger than the values of ion exchangers. The variation in ..cap alpha.. depending on the chemical species was small in the non-aqueous system. High enrichment of lithium isotopes was expected to be achievable by means of the chromatographic application of the cryptand (2 sub(B), 2, 1).
Stress chemiluminescence (SCL) is a novel technique for monitoring aging reactions of polymeric materials under stress. A special apparatus for detecting the chemiluminescence of solid polymers has been designed and built. There is a correlation between an enhanced chemiluminescence signal at low levels of applied stress and subsequent premature mechanical failure of samples of tetraglycidyl-4,4'-methylenedianiline (TGMDA) cured with 4,4'-diaminodiphenyl sulfone (DDS) the most commonly used epoxy in high performance fiber composites. Chemiluminescence data from silicone cushions is used to validate accelerated aging tests and preliminary results from Kevlar fibers are reported. The technique will be extended to other polymeric materials including fiber composites. 22 references, 7 figures, 1 table.
Thin films of sodium montmorillonite clay and cationic polyacrylamide were grown on a polyethylene terephthalate film using layer-by-layer assembly. After 30 clay-polymer layers are deposited, with a thickness of 571 nm, the resulting transparent film has an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation (< 0.005 cc/m{sup 2}/day/atm). This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a brick wall nanostructure comprised of completely exfoliated clay in polymeric mortar. With an optical transparency greater than 90% and potential for microwaveability, this thin composite is a good candidate for foil replacement in food packaging and may also be useful for flexible electronics packaging.
Natural rubber (NR) and its derivatives as renewable and biodegradable materials have attracted considerable attention because of the serious pollution problems caused by synthetic materials and a shortage of resources. A new semi-interpenetrating polymer network (semi-IPN) based on epoxidised natural rubber and polyvinyl alcohol containing maleic acid as a crosslinking reagent was synthesized and characterized by FTIR, XRD, SEM, swelling ratio in both distilled water and toluene, and mechanical properties. The curing time and dose of maleic acid were varied from 10 to 60min, and from 10 to 60% (w/w), respectively. An IR spectroscopic study indicated the presence of an ester linkage at 1730cm-1 in maleic acid crosslinked with PVA in semi-IPN films. In addition, the crystalline content of P...
An effective method of enhancing charge injection and electroluminescence efficiency of polymer-based light emitting diode is introduced. Spin-coated films of poly (N-vinylcarbazole) blended with electron-transport material (Bu-PBD), laser dye (Coumarin6), and the typical supporting electrolyte (tetraethylammonium perchlorate; TEAP) were examined and it was found that the injection current and luminance of the light emitting diode doped with TEAP were enhanced dramatically after heat-treatment at 80 deg. C and appropriate biasing in an external electric field of 1.5x10"8 V/m at this temperature. The thermally stimulated current (TSC) was also measured to investigate the relaxation process of ionic space charges in the films. The relaxation times of ionic polarization were found to be related to the cation size of the electrolyte. And the relaxation time becomes long enough by the use of TEAP doping.
The microstructure of the interphase in semicrystalline polymer matrix composites has a dramatic influence on their mechanical properties. Studies have been performed to alter this region and to correlate various interphase morphologies with changes in fiber-matrix adhesion. A reinforced nylon 66 composite, when subjected to specific thermal histories, contains an interphase composed of transcrystallinity. This region has been altered by coating fibers with a diluent, poly(vinyl pyrrolidone), and/or adding the diluent to the matrix material in very small quantities. Interphase morphology was investigated with optical microscopy, and adhesion was measured using a modified fiber pull-out test. It was found that transcrystallinity increases the interfacial shear strength. The effect different interphase morphologies have on the durability of bulk composite samples is currently under investigation.
In this work, a highly-sensitive polymeric membrane ion selective electrode for determination of tetracycline was constructed by using molecularly imprinted polymer (MIP) particles as quasi-ionophore. The water-compatible MIP particles targeting tetracycline were synthesized with tetracycline as a template molecule, methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, 2,2?-azobisisobutyronitrile as an initiator and lanthanum ion as a mediator. Benefited from the distinctive performance of the quasi-ionophore and the optimized composition of the membrane and the inner filling solution, the lower detection limit of the electrode was decreased to about 1 ? 10?8 mol/l. It exhibited a good electrode slope 59.8 mV/decade near the theoretical Nernstian one, ...
Chitosan was acetylated during 2, 5 and 10 h and physical gels were obtained at different polymer concentrations in N,N-dimethylacetamide containing 5% of LiCl. Acetylation was confirmed by infrared spectroscopy and "1"3C NMR, and degrees of acetylation in the range of 0.82-0.91 were determined by NMR. The O-acetylation degree (0.12-0.15) was exclusively determined by a volumetric method. Rheological studies showed that the storage modulus values were smaller for the more acetylated samples and increased with the temperature and the polymer concentration. All the gels presented storage modulus superior to loss modulus, evidencing more elastic than viscous characteristics. The results obtained in this work suggest a gelation process based on a balance between O and N-acetylation and intermolecular bonds. (author)
This paper explores the through-/in-plane characteristics of water transport in the cathode gas diffusion layer (GDL) of a polymer electrolyte fuel cell (PEFC). Theoretical analysis is performed on the non-isothermal two-phase flow under flow channels. A dimensionless group Da (Damkohler number for PEFC operation), defined as the ratio of water generation rate to water vapor-phase removal rate, is formulated to characterize the flow regimes in a PEFC. This group, lumping geometrical parameters and physical properties, compares the water vapor-phase removal capability (via water diffusion and holding capacity) with the rate of water production by the oxygen reduction reaction. We find that this dimensionless group can be used to characterize the non-isothermal, two-phase phenomena: when Da&...
Most surface-acoustic-wave and thin-film optical devices are made by the planar fabrication process. The exposure of the pattern in the polymer film is the first and most crucial step in ensuring desired device geometry, dimensional control, and freedom from pattern distortion. The methods of exposing the polymer film include: optical projection, conventional contact printing, conformable photomask contact printing, holographic recording, scanning electron beam lithography, projection electron lithography, and x-ray lithography. In this paper scanning electron beam lithography, conformable photomask contact printing, holographic recording, and x-ray lithography are discussed. In the last section, ion beam etching of relief structures is discussed.
Emeraldine base (EB) polymer?ZnO nanoparticles composite films has been synthesized by solution casting technique on ITO-coated glass substrate and characterized by XRD, FTIR and TEM for their structure and morphology. Dielectric behaviour of these composite films has been investigated in the very low frequency region to medium frequency region (1?kHz?1?MHz). The dielectric constant of the composite with 30% nanoparticles is almost one-tenth of the pure EB. The dielectric value becomes constant in the frequency region greater than 400?kHz. The change in dielectric behaviour of the composite is explained on the basis of multilayered interface formed between the ZnO nanoparticles and emeraldine chains. Nanoparticles have high energy surface which is responsible for the decrease of free volum...
Laser-induced phase-separation polymerization of a porous acrylate polymer is used for in-situ fabrication of dialysis membranes inside glass microchannels. A shaped 355 nm laser beam is used to produce a porous polymer membrane with a thickness of about 15 .mu.m, which bonds to the glass microchannel and forms a semi-permeable membrane. Differential permeation through a membrane formed with pentaerythritol triacrylate was observed and quantified by comparing the response of the membrane to fluorescein and fluorescently tagging 200 nm latex microspheres. Differential permeation was observed and quantified by comparing the response to rhodamine 560 and lactalbumin protein in a membrane formed with SPE-methylene bisacrylamide. The porous membranes illustrate the capability for the present technique to integrate sample cleanup into chip-based analysis systems.
Synthetic chemistry originally developed for the manufacture of chemically stable silica polyamine composites was adapted for the modification of fused silica capillaries for application in CE. Polyethyleneimine (PEI) and polyallylamine (PAA) were covalently bonded to the interior surface of fused silica capillaries utilizing 3-chloropropyltrichlorosilane (CPTCS) or 3-glycidoxypropyl-trimethoxysilane (GPTMS) to anchor the polymers to the surface. The surface-bound polymers were subsequently quaternized using methyl iodide (MeI). The resulting modified capillaries were studied using CE, and were shown to provide reproducible, stable, and robust anodic EOF throughout the pH range of 2-10. Surface modifications utilizing CPTCS could be rinsed with up to 6 M HCL or 1 M NaOH without significant...
Biodegradable helicoidal stent prototypes made up of layers of poly-L-lactic acid (PLLA) and poly(L-lactic-co-glycolic acid) (PLGA) polymers were fabricated by temperature conditioning the stents at different stages of fabrication. The process incorporated elastic memory, or self-expandability in the stent, which is desirable to minimize stent recoil. The collapse pressures of such stents were studied, with and without in vitro degradation. The effects of thickness and the composition of each layer on the collapse pressure were modeled using the simple series model. Results of the in vitro studies for over 3 months showed that collapse pressure of the stents depended mainly on the degradation and other side-effects brought about by the degradation of different polymer compositions. General...
The phase separation of (water + salt + polyethylene glycol 15000) systems was studied by cloud-point measurements using the particle counting method. The effect of three kinds of sulphate salt (Na2SO4, K2SO4, (NH4)2SO4) concentration, polyethylene glycol 15000 concentration, mass ratio of polymer to salt on the cloud-point temperature of these systems have been investigated. The results obtained indicate that the cloud-point temperatures decrease linearly with increase in polyethylene glycol concentrations for different salts. Also, the cloud points decrease with an increase in mass ratio of salt to polymer.
Composite materials of synthetics (based on monomers, oligomers and thermoplastics) and of natural polymers (wood and other fibrous cellulosics) prepared by radiation processing, offer valuable structural materials with enhanced coupling forces between the components. The applied polymer chemistry of such composites shows several common features with that of radiation grafting. E.g. the polymerization rate of oligomer-monomer mixtures in wood remains in most cases proportional to the square-root of the initiating dose-rate, just as in the simultaneous grafting, demonstrating that the chain termination kinetics remain regularly bimolecular in the corresponding dose-rate ranges. In the processing experiences of such composites, low dose requirement, easy process-control, and good technical feasibility have been found for composites of wood with oligomer-monomer mixtures, for coconut fibres with unsaturated polyesters and for pretreated wood fibre ...
Composite materials of synthetics (based on monomers, oligomers and thermoplastics) and of natural polymers (wood and other fibrous cellulosics) prepared by radiation processing, offer valuable structural materials with enhanced coupling forces between the components. The applied polymer chemistry of such composites shows several common features with that of radiation grafting, e.g. the polymerization rate of oligomer-monomer mixtures in wood remains in most cases proportional to the square-root of the initiating dose-rate, just as in the simultaneous grafting, demonstrating that the chain termination kinetics remain regularly bimolecular in the corresponding dose-rate ranges. In the processing experiences of such composites, low dose requirement, easy process-control, and good technical feasibility have been found for composites of wood with oligomer-monomer mixtures, for coconut fibres with unsaturated polyesters and for pretreated wood fibre ...
Experimental results of quasi-static and dynamic fracture of particle-filled polymer composite (PFPCM) "ALTUGLAS EI CH25" with a matrix of polymethylmethacrylate (PMMA) are reported in this paper. PMMA matrix is filled with rubber particles, as result a shock-resistant transparent composite is produced. The main task was to investigate experimentally and theoretically the fracture toughness of this composite under static and dynamic loading. A high-rate loading has been created by impulse magnetic field. Analysis of fracture process and its relation with the load parameters and material microstructure have been established. Application of the original testing method enabled determination of fracture toughness at very short loading times and comparison of the results with material dynamic p...
Abstract:- Significant interest has emerged in the introduction of food packaging materials manufactured from biodegradable polymers that have the potential to reduce the environmental impacts associated with conventional packaging materials. Current technologies in active packaging enable effective antimicrobial (AM) packaging films to be prepared from biodegradable materials that have been modified and/or blended with different compatible materials and/or plasticisers. A wide range of AM films prepared from modified biodegradable materials have the potential to be used for packaging of various food products. This review examines biodegradable polymers derived from polysaccharides and protein-based materials for their potential use in packaging systems designed for the protection of food ...
Several challenges currently exist for rational design of functional tissue engineering constructs within the host, which include appropriate cellular integration, avoidance of bacterial infections, and low inflammatory stimulation. This work describes a novel class of biodegradable, amphiphilic polyanhydrides with many desirable protein-material and cell-material attributes capable of confronting these challenges. The biocompatible amphiphilic polymer films were shown to release laminin in a stable and controlled manner, promote neural cell adhesion and differentiation, and evade inflammatory responses of the immune system. Using high-throughput approaches, it was shown that polymer chemistry plays an integral role in controlling cell?film interactions, which suggests that these polyanhyd...
Fibre-reinforced-polymer-composite material has been suggested as a bearing material to overcome tribological problems witnessed during the testing of Ram assembly of the 540 MWe fuelling machine at RTD. After successful trials at B-Ram the composite material has been adapted for B-RAM, C-Ram and RDB head at fuelling machines being tested at RTD, Hall 7 and at Tarapur. Laboratory evaluations were also carried out at Tribology Lab RTD to study effect of radiation on the composite. Paper deals with the various aspects of life prediction of this material in term of wear and radiation damage. (author)
Abstract A control framework was developed for real time implementation of optimal control of emulsion polymerization with multiple monomers by integrating model based algorithms with software engines. The developed system was applied for controlling conversion, particle size, molar mass, and polymer composition using model predictive control (MPC) based on mechanistic models for emulsion polymerization. The control formulation was extended to account for existing process constraints on the input, input moves, and solids content. On experimental testing, the developed control scheme was found to achieve the desired objectives without violating the process constraints and showed good robustness in rejecting disturbances. Improvements in the process operation and polymer property control wer...
A variable gene delivery system has been developed based on conjugating chitosan to biotin through a functionalized poly(ethylene glycol) (PEG) spacer, which can be used to further bind different molecules on the outer layer of a polymer/DNA complex by streptavidin (SA)-biotin linkage. In this study, TAT-conjugated SA was used as the model molecule to prove the conjugation function of the prepared complex. In addition, low-molecular-weight poly(ethyleneimine) (PEI) was added into the polymer/DNA complex to increase the transfection efficiency. The results of the luciferase assay show that the transfection efficiency of the prepared complex was significantly correlated with the amount of PEI and was further enhanced when TAT was conjugated to the complex by SA-biotin linkage. Considered to have negligible cytotoxic effects, the variable gene delivery complex prepared in this study would be of considerable potential as carriers for in vitro ...
Wood-Polymer Composites (WPC) was prepared from recycled films of agricultural use and wood wastes, and LLDPE and neat PE resin mixture were also utilized in order to compare the properties. Maleic anhydride (MA) and dicumyl peroxide were used as an adhesion promoter and an initiator, respectively. Tensile properties of WPC were measured via tensile test as a function of wood filler and MA content, and fracture surface was also investigated with SEM. As the content of wood filler increased, elongation decreased but modulus increased. However, tensile strength of WPC increased only when MA was used, and 1 wt.% of MA may be high enough to increase the tensile properties. The tensile properties of WPC prepared from recycled PE films were almost same as those of neat PE resin mixture. (author). 18 refs., 5 figs.
Detailed investigations of geologic, geomorphic, and seismic conditions at the Bodo Canyon disposal site were conducted. The purpose of these investigations was basic site characterization and identification of potential geologic hazards that could affect long-term site stability. Subsequent engineering studies, such as analyses of hydrologic and liquefaction hazards, used the data developed in these studies. The geomorphic analysis was employed in the design of effective erosion protection. Studies of the regional and local seismotectonic setting, which included a detailed search for possible capable faults within a 65 kilometer radius of the site, provided the basis for seismic design parameters. The scope of work performed included the following: Compilation and analysis of previous published and unpublished geologic literature and maps; Review of historical and instrumental earthquake data; Review ...
The environmental data for the NSDN are presented in the form of tables for each solar site. The solar sites are grouped into 12 zones, each of which consists of several adjacent states. The solar energy sites are in alphabetical sequence within each zone. The tables provide available meteorological data for reporting sites in the NSDN as follows: Insolation - the insolation table presents the total, diffuse, direct, maximum, and extra-terrestrial radiation for the solar site. It also shows the ratio of total extra-terrestrial radiation, as a percent. Temperature - the temperature table gives the average, daytime, nightime, maximum, minimum and inlet-water temperatures for the solar site. Additional tables are presented for some of these NSDN sites, supplying either wind or relative humidity data, or both. Wind - all of the passive and some ...
The Department of Energy`s Office of Technology Development initiated an Integrated Demonstration Program at the Savannah River Site in 1989. The objective of this program is to develop, demonstrate, and evaluate innovative technologies that can improve present-day environmental restoration methods. The Integrated Demonstration Program at SRS is entitled ``Cleanup of Organics in Soils and Groundwater at Non-Arid Sites.`` New technologies in the areas of drilling, characterization, monitoring, and remediation are being demonstrated and evaluated for their technical performance and cost effectiveness in comparison with baseline technologies. Present site characterization and monitoring methods are costly, time-consuming, overly invasive, and often imprecise. Better technologies are required to accurately describe the subsurface geophysical and geochemical features of a site and the nature and extent of ...
The Davis GSR Landfill (GSR) is listed by the U.S. Environmental Protection Agency on the National Priorities List. Preliminary on-site sampling results have demonstrated volatile organic compounds in ground water and surface water. The contaminants present in groundwater at this site are trichloroethylene, ethylbenzene, toluene, chloromethane, tetrahydrofuran, 1,1,1-trichloroethane, and 1,2 dichloroethane. GSR represents a potential public health concern to area residents. However, information available on this site is not currently adequate to determine if a public health concern exists to these residents. At a minimum, future investigations of this site should include a characterization of the site and site contaminants, and a characterization of the hydrogeology of the area.
Thinning and burning forests established on revegetated mine pits in jarrah (Eucalyptus marginata) forests of south-west Australia is being considered as a management option to accelerate succession in sites with excessive tree densities. To assess the impact of thinning and burning on reptiles and small mammals, we installed trapping grids in eight thinned and burned sites, each paired with untreated controls. Of the eight pairs, four were in rehabilitated sites (planted with nonlocal species) and four were in restored sites (seeded with local species). Thinning and burning had no significant impact on the small mammal community, although Cercatetus concinnus was more abundant in rehabilitated sites. In contrast, thinning and burning significantly increased reptile abundance and species r...
The diffusion characteristics of water in polymer materials have been studied for a few decades. Several methods have been developed to provide water diffusion characteristics as a function of time, temperature, pressure, or thickness of polymer. Unfortunately, most of these methods give the amount of water absorbed as a function of weight versus time at given environmental conditions. Concentration profiles of the water diffusion through the polymer have been unobtainable by these established methods. Neutron radiography is a method of non-destructive testing that has grown rapidly over the past ten years and is capable of giving these concentration profiles. Epoxy is one of the most commonly used polymers for which water diffusion information is important. In the automotive industry, epoxy is used both as a sealant and a bonder to prevent water from getting inside structures and causing corrosion. To ...
Methods of preparation, stability in solutions and in the solid phase, composition of orthophosphate crystallohydrates and condensed uranyl- and uranium (4) phosphates, are considered. Structures of these compounds are discussed; it is shown that they are steric polymers with an uranylphosphate framework. The problem of phosphate-anion polymerization in the process of thermal decomposition is discussed. It is established that condensed uranyl polyphosphates are not stable during storage, capable of degradation, its degree increasing with the phosphate chain length and uranium content.
Polyamide is a modifier which introduces flexibility and toughness to phenolic foam by non reactive approach. Phenol formaldehyde resin was physically modified by the addition of polyamide in different percentages ranging from 0.05% to 0.2% which introduced toughness to modified resole. The resultant polymers were characterized by thermal and mechanical analysis using Thermogravimetric Analyzer (TGA), Instron machine and Dynamic Mechanical Analyzer (DMA). (author)
The synthesis and structures of acyclic and macrocyclic thio-, seleno- and telluro-ether complexes of the metallic and metalloid elements of Groups 13-16 reported since 2000 are described. The diverse structures range from discrete monomers through to infinite 1-, 2- or 3-D polymers. The coordination chemistry in this area is quite different to familiar d-block chemistry and the underlying factors are explored. PMID:21706103
The equilibrium dynamic capacity of polymer materials based on 2,4,6-triamino-1,3,5-triazine has been determined. The possibility of their application as absorbents of sulfur dioxide from exhaust gases has been shown.
MMP, a linear alpha 1 leads to 4 linked polymer of 3-O-methylmannose, regulates the fatty acid synthetase from Mycobacterium smegmatis by forming stoichiometric complexes with the long-chain acyl-CoA...Full Text Available
Stress relaxation was studied at 408 K on AZ31 reinforced by ceramic foam produced by in situ foaming of filler loaded preceramic polymer melt. Reinforcement causes significant enhancement of the resistance against stress relaxation compared to AZ91. It is correlated with hardening by the ceramic skeleton as well as ceramic particles formed in the AZ31-matrix. (orig.)
The pace of development and fielding of electric vehicles is briefly described and the principal advanced battery chemistries expected to be used in the EV application are identified as Ni/MH in the near term and Li-ion/Li-polymer in the intermediate to long term. The status of recycling process development is reviewed for each of the two chemistries and future research needs are discussed.
In the present work, range and energy loss rate of "2"8Si in four dielectric track detectors viz: Makrofol-KG (MFKG), Makrofol-G (MFG), Triafol-BN (TBN) and LR-115 (cellulose nitrate) have been measured. To calculate these parameters, a curve fitting method was proved to be very useful and easier with more accuracy. (author)
Poly(methyl methacrylate), PMMA, Acrigel, a Brazilian polymer, is used in the manufacture of medical supplies sterilisable by ionizing radiation. However, when PMMA is gamma-irradiated it undergoes main chain scissions, which promote molecular degradation causing reduction in its physical properties. Therefore, radiolytic stabilization of PMMA is important for to become it commercially radio sterilisable. In this work we investigated the radiolytic stabilization of PMMA by using HALS (Hindered Amine Light Stabilizer) additive, commercially used for photo and thermo oxidative stabilization of polymers. The investigation of the radiation-induced main chain scissions was carried out by viscometric method. The additive added to the polymer system at 0.3 % w/w promotes a molecular radioprotection of 61%. That means a reduction of G value (scissions/100 eV) from 2.6 to 1.0. In addition, the glassy transition temperature (Tg) of ...
Abstract A diacrylate polysulfone oligomer is synthesized and used as the acrylic oligomer for the in situ synthesis of noble metal/PSU nanocomposites through UV-induced simultaneous radical polymerization of acrylic functionalities and NP formation by reduction of their precursors. Thus, silver or gold NPs are formed in situ during polymer network formation. FESEM analysis of the morphology of the cured systems demonstrates that the nanoparticles of the noble metals are homogeneously distributed in the network without macroscopic agglomeration.
This project has been concerned with the understanding of certain key physical and physical chemical properties of polymeric systems which are related to their use as working substances in mechanochemical systems. Since the crystal-liquid phase transition is involved in the process of interest, attention has been focused on this transition and on the properties of semi-crystalline polymers. Two kinds of behavior and properties have been studied in this program. One of these is concerned with melting-crystallization under an applied external force. Here the primary matters of concern are the equilibrium melting temperature-stress relations and the associated problem of crystallization kinetics under an applied external stress. The other area of study involves mechanical properties, with particular emphasis on the influence of the morphological and structural variables which describe the semi-crystalline state. We have taken advantage in this work of concurrent ...
This report forms part of a joint study on a PEFC propulsion system for surface ships, summarized in a presentation to this Seminar, entitled {open_quotes}Study on a Polymer Electrolyte Fuel Cell (PEFC) Propulsion System for Surface Ships{close_quotes}, and which envisages application to a 1,500 DWT cargo vessel. The aspect treated here concerns an experiment in reducing by methanation to a level below 10 ppm the CO that is contained to around 1% in reformate gas.
Lithium metal-polymer electrolyte batteries with improved utilisation of the active material at a moderate-low temperature (65degC) were realised. Low molecular weight poly(ethylene glycol) (PEG, MW=2000) was used as the lithium-ion conductive matrix in the composite cathode. The cathode active material was crystalline V{sub 2}O{sub 5}. A blend of poly(ethylene oxide) (PEO, MW=4x10{sup 6}) and PEG was used as a solid polymer electrolyte (SPE). The transport properties of the SPE were evaluated at various temperatures. A specific conductivity as high as 1.0x10{sup -4} S cm{sup -1} was calculated at 45degC. The temperature dependence of the interfacial resistances between lithium/SPE and cathode material/PEG was evaluated. The lithium/SPE interfacial resistance decreases linearly with the temperature. The charge transfer resistance between cathode material and PEG reaches a minimum at 60degC and it does not decrease with a further temperature ...
The use of polymer matrix composites in aerospace propulsion applications is currently limited by insufficient resistance to erosion by abrasive media. Erosion resistant coatings may provide necessary protection; however, adhesion to many high temperature polymer matrix composite (PMC) materials is poor. A low pressure oxygen plasma treatment process was developed to improve adhesion of CN_x coatings to a carbon reinforced, fluorinated polymer matrix composite. Fullerene-like CN_x was selected as an erosion resistant coating for its high hardness-to-elastic modulus ratio and elastic resilience which were expected to reduce erosion from media incident at different angles (normal or glancing) relative to the surface. In situ x-ray photoelectron spectroscopy was used to evaluate the effect of the plasma treatment on surface chemistry, and electron microscopy was used to identify changes in the surface morphology of the PMC ...
...of Mixing Sections 9 Interacting Rotor/Stator Mixers 10 Floating Ring Mixing Devices 11 Static (or Motionless) Mixers 12 Incorporation of Liquid Additives and Dispersions by Direct Addition 13 Dispersive Mixing of Fillers and Pigments 14 Dispersive Mixing Applied to Polymer Blending 15 Compounding with Single Screw Extruders Appendix - Preparation of Microtome Sections for Assessment of Dispersive In order to get a feel for this book, you can view Chapter 1 now, simply follow the link ...
Microwaves improve the rate of many chemical reactions either interacting with the solvent, when the reaction is carried out in solution, or with the surface of a solid substrate where a suitable reagent is dispersed (dry chemistry). A few examples of chemical reactions positively affected by microwaves are described: particularly interesting are those concerning polymers and radio-pharmaceuticals.
The bibliography contains citations concerning industrial uses and design of microwave heating equipment. Included are heating and drying of paper, industrial process heat, vulcanization, textile processing, metallurgical heat for sintering and ceramic manufacturing, food processing, and curing of polymers.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)
The production of water from a subterranean formation is reduced by contacting the formation with a water dispersible hydrophilic organic polymer having a molecular weight greater than 100,000 and containing carboxyl functionality and a crosslinking composition comprising water, a zirconium compound having a value of 4+, an alpha-hydroxy acid and an amine compound.
European phosphorus derivatives manufacturer Italmatch Chemicals SpA has expanded its Phoslite range of fully colourable flame retardants for polymers with the addition of Phoslite B85AX. The company reports that its Phoslite technology is already `successfully consolidated' in polypropylene (PP) applications and, with introduction of the new product, is now starting to expand into polyamide PA6 and polybutylene terephthalate (PBT) applications.
A high voltage oil-impregnated electrical cable with fully polymer taped insulation operable to 765 kV. Biaxially oriented, specially processed, polyethylene, polybutene or polypropylene tape with an embossed pattern is wound in multiple layers over a conductive core with a permeable screen around the insulation. Conventional oil which closely matches the dielectric constant of the tape is used, and the cable can be impregnated after field installation because of its excellent impregnation characteristics.
Radiation sterilization has several merits that it is a positively effective sterilization method, it can be used to sterilize low heat-resistant containers and high gas barrier films, and there is no possibility of residual chemicals being left in the packages. It has been commercially used in 'Bag in a Box' and some food containers. The #gamma# ray and an electron beam are commonly used in radiation sterilization. The #gamma# ray can sterilize large size containers and containers with complex shapes or sealed containers due to its strong transmission capability. However, since the equipment tends to be large and expensive, it is generally used in off production lines. On the other hand, it is possible to install and electron beam system on food production lines since the food can be processed in a short time due to its high beam coefficient and its ease of maintenance, even though an electron beam has limited usage such as sterilizing relatively thin materials and surface ...
The electrophysical characteristics of the electric cable?s transition into a state of a heterogenic polymer system due to a wire?s explosion were examined. Using cyclic heating-cooling of the composite, the changes in its topology were observed. The latter makes it possible to regulate the dielectric characteristics of the system.
The method of surface acoustic waves is employed to determine the frequency and temperature dependences of the molar heat capacity of poly(vinyl chloride) on the contribution of Rayleigh local components of the longitudinal and transverse vibrations of structural units of the polymer. The calculated and experimental data are compared in terms of their dependence on the relaxation state of the system.
A series of N-carbazolyl-substituted silane homo- and copolymers has been prepared by Wurtz coupling. Doping with iodine on these copolymer films increases the electrical conductivity to the range 10{sup -6}-10{sup -3} S cm{sup -1}. The conductivity depends strongly on the composition of the copolymer; it reaches the maximum value for N-carbazolyl-substituted silane homopolymer. The effects of carbazolyl group on conductivity and charge transport mechanisms in the polymer are discussed. (orig.)
A solid electrolyte for lithium batteries requires several properties: a good ionic conductivity of about 10{sup -3} S/cm at 298 deg. K, a high cationic transport number (greater than 0.5), a redox stability window higher than 4.5 V, a good stability of the interface with the lithium electrode, and a sufficient mechanical stability. The family of gelled or hybrid electrolytes seems to meet all these requirements. Thus, a systematic study of the gelling of an ethylene carbonate and lithium bistrifluorosulfonimide (LiTFSI) based electrolyte has been carried out. The polymers used for gel or pseudo-gel synthesis are POE, PMMA and PAN which represent 3 different cases of interaction with the electrolyte. All the properties mentioned above have been studied according to the nature of the polymer and to the concentration of lithium salt, showing the advantages and drawbacks of each polymer. The possibility of using some of these ...
Most chemical reactions in industry and biology are catalytic and play a role at some stage of the processing of about 80% of the goods manufactured in the U.S., yet catalysis is a neglected subject in chemical education. This book integrates the fragmentary treatment accorded the topic until now. It covers, in a unified way, catalysis in solutions, by enzymes, in synthetic polymers within the molecular scale cages of zeolites and other molecular sieves, and on surfaces of inorganic solids. The central ideas are chemical; and principles are illustrated by emphasizing industrial reactions and catalysts.
Deposition of CN-based films by a novel version of active screen plasma nitriding, aiming at surface modification of polymers, is reported. The approach relies on the use of pure graphite as the grid material, which was found to act both as an active screen and as a dry source of carbon atoms for the synthesis of thin films consisting mainly of a stoichiometric CN layer with columnar-type structure and dome-like nanostructured morphology.
Biodegradable polymers for use in environmental waste-management has been the subject of much discussion over the last few years. Polyurethane mixtures with polysaccharide (80/20 and 90/10 w/w ) have been prepared and films obtained. These films were inoculated, according to ASTM G22-76 rule and analysed by thermogravimetry and scanning electronic microscopy (SEM). The results are discussed in terms of thermal degradation and biodegradability. (author)
Analysis of damages done by the radiation in a polymer characterized by optic properties of polished surfaces, of uniformity and chemical resistance that the acrylic; resistant until the 150 centigrade grades of temperature, and with an approximate weight of half of the glass. An objective of this work is the development of a method that analyze in automated form the superficial damages induced by radiation in plastic materials means an images analyst. (Author)
The doping of deuterated polyparaphenylene [C_6D_4]sub(n) with AsF_5 has been investigated by real time neutron diffractometry at 100, 400 and 820 mbar AsF_5 pressure. The reaction appears to be diffusion controlled. Evidence for one doped phase with partial crystalline order was obtained. Structural considerations suggest two polymer chains plus one dopant ''string'' as the repetitive unit. (Auth.).
A method is proposed for making a drilling mud, which includes mixing of an aqueous solution of a water soluble acrylic polymer with clay. It is distinguished by the fact that in order to reduce the corrosion activity of the clay solution, the dry clay is slaked in an aqueous solution of partially hydrolized polyacrylonitrile with the following component relationship (in percent by mass): clay, 3 to 10; hydrolized polyacrylonitrile, 3 to 5 and water, the remainder.
Full text: The site selection process for a near surface repository dedicated for the radioactive waste resulted from the Cernavoda NPP operation and decommissioning started early in 90's. Each site selection stage included the collection of data from specific field and laboratory works as well as the appropriate safety performance evaluation. In order to assess/confirm the performance of the natural barrier of the Saligny site, the radionuclide concentration in the disposal system compartments has been evaluated, as complementary safety indicator of repository. The siting process was made in accordance with national and international regulations and standards and using a conceptual design similar to those used at L'Aube (France), ElCabril (Spain) or Mohovce (Slovak Republic). ANDRAD, the Romanian waste management organization that has continued the siting process in the last three ...
BackgroundWe aimed to compare visual and refractive outcome following phacoemulsification and intraocular lens implant (IOL) and combined one-site phacotrabeculectomy.MethodWe...Full Text Available
Subcellular-fractionation techniques were used to characterize the endocytic pathway followed by ricin in rat liver in vivo and tentatively identify the site(s) at which the ricin interchain disulphide...Full Text Available
Our research in the general area of acid catalysis involves the characterization of solid acidity and the corresponding assessment of catalytic performance of acidic materials. Acid characterization studies are required to provide essential information about the type of acid site (i.e., Lewis versus Bronsted), the strength of the sites, and the mobility of molecules adsorbed on the acid sites. An accurate measure of acid strength is given by the heat of adsorption of a basic probe molecule on the acid site. A thermodynamic representation of the mobility of adsorbed species on these sites is given by the entropy of adsorption. Important techniques used in these acid site characterization studies include microcalorimetry, thermogravimetric measurements, temperature programmed desorption, infrared spectroscopy and solid state nuclear magnetic resonance. The ...
Paraquat poisoning in mammals results in a characteristic lung lesion manifested principally as progressive pulmonary fibrosis. Paraquat is actively concentrated into the lung but the site of uptake remains undefined. A method is described for the autoradiographic localization of paraquat in rats. Preliminary evidence for the site of uptake implicates the bronchiol. (author).
The U.S. Department of Energy (DOE) has developed comparatively detailed quality assurance requirements for the high-level radioactive waste disposal systems. Quality assurance is recognized as a key issue for confidence building and smooth implementation of the HLW program in Japan, and Japan is at an initial phase of repository development. Then the quality assurance requirements at site research and site selection, site characterization, and site suitability analysis used in the Yucca Mountain project were examined in detail and comprehensive descriptions were developed using flow charts. Additionally, the applicability to the Japan high-level radioactive waste disposal project was studied. The examination and study were performed for the following QA requirements: The requirements that have the relative importance at site research and site selection, ...
Experiments were carried out to learn methanol sorption characteristics of heat-treated coal. When Taiheiyo coal is heat-treated at 125{degree}C, performed with a first methanol adsorption at 25{degree}C, and then desorption at 25{degree}C, a site with strong interaction with methanol and a site with relatively weak interaction are generated in test samples. A small amount of methanol remains in both sites. Then, when the methanol is desorbed at as low temperature as 70{degree}C, the methanol in the site with strong interaction remains as it has existed therein, but the methanol in the site with relatively weak interaction desorbs partially, hence the adsorption amount in a second adsorption at 25{degree}C increases. However, when desorption is performed at as high temperature as 125{degree}C, the methanol in the site with strong interaction also desorbs, ...
Human chromosomal fragile sites are specific loci that are especially susceptible to DNA breakage following conditions of partial replication stress. They often are found in genes involved in tumorigenesis...Full Text Available
This report documents site remediation at ORNL, including ORNL site characterization technologies, waste management and robotics and automation of the laboratory for waste processing and analysis.
The integration sites for viral DNA in cells infected with Moloney murine leukemia virus (M-MuLV) were studied by restriction endonuclease cleavage of cellular DNA followed by electrophoresis in agarose...Full Text Available
Chromosomal common fragile sites (CFSs) are genetically unstable regions of the genome that are induced by conditions that impair DNA replication. In this report, we show that treatment with the DNA...Full Text Available
Brownfields redevelopment contributes to the revitalization of communities across the U.S. Reuse of these abandoned, contaminated sites spurs economic growth, builds community pride, protects public health, and helps maintain our nation's "greenfields," often at a relatively low ...
UK Nirex has announced four sites which it wishes to assess for the disposal of low-level and short-lived intermediate-level radioactive wastes. There is local opposition at all four of the potential sites. (U.K.).
The Protein Data Bank contains the description of more than 45,000 three-dimensional protein and nucleic-acid structures today. Started to exist as the computer-readable depository of crystallographic...Full Text Available
Photobilirubin II, a stereoisomer of bilirubin, binds to human serum albumin at a single binding site (K = 2.2 x 10(6)M-1), presumably the high-affinity bilirubin-binding site. Binding in the secondary...Full Text Available
BackgroundA relevant problem in drug design is the comparison and recognition of protein binding sites. Binding sites recognition is generally based on geometry often combined with...Full Text Available
Brine from active oil wells seeped through the soil of a forested site in north-western Pennsylvania and killed all vegetation in its path, leaving the affected area unproductive and unsightly. After the brine source was eliminated, herbaceous plants, shrubs and forest tree seedlings became established and developed rapidly. Establishment began in the first year and by Year 4 the site had developed into a healthy young forest. Results show that Allegheny hardwood forest sites damaged by brine water will rapidly revegetate once the brine water discharge is stopped if there is a seed supply and if the area is fenced to exclude deer. 3 figs., 12 refs.
Surface temperature is measured with an infrared thermometer. Measuring Surface Temperature. Nine sample points are selected with a site of uniform land ...
In accordance with the requirements of Section 113 (b) (3) of the Nuclear Waste Policy Act of 1982, as amended (NWPA), the US Department of Energy (DOE) has prepared this report on the progress of site characterization activities at Yucca Mountain, Nevada, for the period October 1, 1990, through March 31, 1991. This report is the fourth in a series of reports that are issued at intervals of approximately six months during site characterization. The report covers a number of initiatives to improve the effectiveness of the site characterization program, and covers continued efforts related to preparatory activities, Study Plans, and performance assessment.
The Savannah River Site has successfully used robots, teleoperators, and remote video to reduce exposure to ionizing radiation, improve worker safety, and improve the quality of operations. Previous reports have described the use of mobile teleoperators in coping with a high level liquid waste spill, the removal of highly contaminated equipment, and the inspection of nuclear reactor vessels. This report will cover recent applications at the Savannah River, as well as systems which SRS has delivered to other DOE site customers.
This document outlines the major steps that must be taken by the Savannah River Site (SRS) to migrate the SRS information technology (IT) environment to the new architecture described in the Savannah River Site Computing Architecture. This document proposes an IT environment that is {open_quotes}...standards-based, data-driven, and workstation-oriented, with larger systems being utilized for the delivery of needed information to users in a client-server relationship.{close_quotes} Achieving this vision will require many substantial changes in the computing applications, systems, and supporting infrastructure at the site. This document consists of a set of roadmaps which provide explanations of the necessary changes for IT at the site and describes the milestones that must be completed to finish the migration.
Using low-temperature adsorbed dihydrogen and carbon monoxide as molecular probes, the dehydroxylation of the hydrogen forms of the zeolites Y, and ZSM-5 has been studied. The high stability of the high-silica zeolites to dealumination and their difference from faujasites has been established as being due not only to the strength of their Broensted acid sites but also to the nature of their Lewis acid sites. The chemical properties of the Lewis acid sites and their possible role in catalytic reactions are discussed.
A three dimensional sea-land breeze model has been employed for the study on the inland penetration of sea breeze around Wolsung NPP site. In this study, the sea breeze simulation was carried out under the weak northwesterly geostrophic wind (3.2 m/s, 339 .deg.) at 850 hPa in Spring. The results showed that sea breezes developed near Wolsung site penetrated into about 20 km inland under the weak northwesterly geostrophic wind in Spring. This result agreed with observation data around Wolsung site on May 1996.
A three dimensional sea-land breeze model has been employed for the study on the inland penetration of sea breeze around Wolsung NPP site. In this study, the sea breeze simulation was carried out under the weak northwesterly geostrophic wind (3.2 m/s, 339 .deg.) at 850 hPa in Spring. The results showed that sea breezes developed near Wolsung site penetrated into about 20 km inland under the weak northwesterly geostrophic wind in Spring. This result agreed with observation data around Wolsung site on May 1996.
This plan outlines the procedures and operations used at LLNL's Site 300 for the management of the hazardous waste generated. This waste consists primarily of depleted uranium (a by-product of U-235 enrichment), beryllium, small quantities of analytical chemicals, industrial type waste such as solvents, cleaning acids, photographic chemicals, etc., and explosives. This plan details the operations generating this waste, the proper handling of this material and the procedures used to treat or dispose of the hazardous waste. A considerable amount of information found in this plan was extracted from the Site 300 Safety and Operational Manual written by Site 300 Facility personnel and the Hazards Control Department.
New technological advances make it possible to perform on site gas-in-oil analysis quickly and efficiently. Gas-in-oil analysis is crucial in assessing the status of oil-filled electrical equipment. The new technique is used for extracting and measuring gases dissolved in electrical insulating oil. On-site sampling requires the use of a specially designed 100 ml capacity syringe. Extraction of the dissolved gases is made with a precise ratio of oil to air. A comparison was made between the analysis of the on-site and the laboratory techniques. Results showed that the detection limits of the on-site technique were comparable to those obtained by laboratory methods.
A complete electron paramagnetic resonance power pattern characterization of Fe"3"+ in cubic sites in presented. A one-to-one correspondence among the peaks appearing in the powder pattern and the outer fine-structure transitions (Mnot = 1/2 ) observed in the single crystal along the , , and directions is shown. It is shown that the process of mechanically grinding the single crystal to a powder (particle size approx.1--10 #mu#) does not remove the cubic symmetry sites. No axial or lower symmetry sites which may be induced by lattice distortion of the crystallites due to strain have been observed.
Aluminum electrolytic capacitors have a long history of reliable operation in unattended field sites. However, their use in the expected space applications ...
Volume four contains calculations for: Borrow areas--site evaluation; temporary facilities--material quantities; embankment quantities--excavation and cover materials; Burro Canyon site excavation quantities--rippable and unrippable materials; site restoration--earthwork quantities and seeding; and bid schedule quantities and material balance.
We apply our work on fracture- and matrix-dominated flow to develop a conceptual model of hydrological flow processes in the unsaturated zone at Yucca Mountain. The possibility of fracture-dominated flow is discussed, and various deductions are made on its impact on natural and total system performance, site characterization activities, and site suitability determination.
1. The fluorescent fatty acid probe 11-(dansylamino)undecanoic acid (DAUDA) binds with high affinity to bovine and human serum albumin (BSA and HSA) at three sites. 2. The Kd of the primary binding...Full Text Available
In rat adipocyte membranes, both beta-adrenergic agonists and beta-adrenergic antagonists competed with (--)(/sup 3/H)dihydroalprenolol for high affinity (KD 2-4 nM) and low capacity binding sites. The antagonists but not the agonists competed with (--)(/sup 3/H)dihydroalprenolol for lower affinity and higher capacity sites. The present studies were performed in order to characterize the adipocyte beta-adrenergic receptor and distinguish it from low affinity, higher capacity sites which were heat-labile and not stereoselective. When isoproterenol was used to define the nonspecific binding, saturation studies showed a single binding site with a capacity of approximately 100 fmol/mg membrane protein (corresponding to approximately 50,000 sites/adipocyte). Binding was saturated by 10 nM (--)(/sup 3/H)dihydroalprenolol. Approximate KD's of 204 nM were observed. Kinetic analysis ...
We report the existence of a sixth replication arrest site, TerF, that is located within the coding sequences of the rcsC gene, a negative regulator of capsule biosynthesis. The TerF site is oriented...Full Text Available
Human serum albumin (HSA) has two primary binding sites for drug molecules. These sites selectively bind different dansylated amino acid compounds, which—due to their intrinsic fluorescence—have...Full Text Available
This volume contains appendices D6 through D8 containing laboratory test data: from MK-F investigation, 1987, Old Rifle and New Rifle sites; on bentonite amended radon barrier material; and from MK-F investigation, 1987, riprap tests.
The purpose of this interim remedial measures (IRM) proposed plan is to present and solicit public comments on the IRM planned for the 200-ZP-1 Operable Unit at the Hanford Site in Washington state. The 200-ZP-1 is one of two operable units that envelop the groundwater beneath the 200 West Area of the Hanford Site.
Papers presented at a meeting on indoor and outdoor climates on sites polluted with volatile organic chemicals. The papers deal with the subject of evaporation of organic chemicals on the polluted sites in relation to the influence on indoor and outdoor climates. Themes dealt with are diffusion through soils and transport of pollutants from the soil into buildings. (AB).
The Department of Energy's National Solar Data Program established solar energy systems in residential and commercial buildings across the United States. These solar sites are linked to Vitro Laboratories Division's computer in the National Solar Data Network (NSDN). Vitro collects and analyzes data from this network to determine the thermal performance of each of the solar systems. The network consists of: (1) sensors which measure key performance parameters at a selected site; (2) a Site Data Acquisition Subsystem (SDAS); (3) telephone transmission circuits; and (4) a Central Data Processing System (CDPS). For the majority of parameters, raw data is collected approximately every five minutes. Solar insolation and certain other parameters, which are subject to rapid variance, are sampled every 32 seconds. Environmental information collected at the sites for the reporting month are ...
Nomographs have been developed to simplify site performance estimates for various types of gas turbine engines used for industrial applications. The nomographs can provide valuable data for engineers to use for an initial appraisal of projects where gas turbines are to be considered. General guidelines for the selection of gas turbines are also discussed. In particular, site conditions that influence the performance of gas turbines are described.
EPA's Brownfields Economic Redevelopment Initiative was established to assist states, site planners and other community stakeholders to work together to assess, cleanup and sustainably reuse brownfields sites. EPA has developed a series of guides to help these parties effectively...
This report has been prepared in conjunction with an environmental baseline study for a commercial coal conversion facility being conducted by Ashland Synthetic Fuels, Inc. (ASFI) and Airco Energy Company (AECO). This report represents a cultural resource assessment for the proposed plant site and two potential solid waste disposal areas. This assessment presents data collected by Dames and Moore during a recent archaeological reconnaissance of the unsurveyed southeastern portion of the proposed plant site and two potential solid waste disposal areas. Also, results of two previous surveys on the northern and southwestern portion of the plant site for American Smelting and Refining Company (ASARCO) and Kentucky Utilities are included. The Dames and Moore survey of the southeastern portion of the plant site identified one archaeological site, three standing structures and one historic ...
Surveillance and maintenance (S & M) of 75 sites were conductd by the Remedial Action Section for the Environmental Restoration Program for surplus facilities and sites contaminated with radioactive materials and/or hazardous chemicals. S & M activities on these sites were conducted from the end of their operating life until final facility disposal or site stabilization. The objectives of the Waste Area Grouping S & M Program are met by maintaining a program of routine S & M as well as by implementing interim corrective maintenance when deemed necessary as a result of site surveillance. This report briefly presents this program`s activities and includes tables indicating tank levels and dry well data for FY 1991.
Surveillance and maintenance (S M) of 75 sites were conductd by the Remedial Action Section for the Environmental Restoration Program for surplus facilities and sites contaminated with radioactive materials and/or hazardous chemicals. S M activities on these sites were conducted from the end of their operating life until final facility disposal or site stabilization. The objectives of the Waste Area Grouping S M Program are met by maintaining a program of routine S M as well as by implementing interim corrective maintenance when deemed necessary as a result of site surveillance. This report briefly presents this program's activities and includes tables indicating tank levels and dry well data for FY 1991.
Mining of copper and zinc took place at the Clinton Mine located in the Estrie region of Quebec between 1973 and 1975, during which time 115,000 tons of mineral were treated at the Solbec plant. In this poster presentation, the authors provided the background information pertaining to this mine and described the state in which it was in 1994. The pit was covered with good quality water, with a pH of 7,1 and copper and zinc content ranging between 0,1 and 0,6 mg/l, and iron ranging between 0,2 and 1,8 mg/l. The tailings basin drainage was found to have a pH of between 3,6 and 6,1. A program for the characterization of the site was implemented and the concept for the restauration of the Clinton site was developed and implemented. The work carried out at the site is discussed during this presentation as well as the monitoring taking place. 27 figs.
This remedial investigation (RI)/feasibility study (FS) supports the selection of remedial actions for the David Witherspoon, Inc. 901 Maryville Pike Site in Knoxville, Tennessee. Operations at the site, used as a recycling center, have resulted in past, present, and potential future releases of hazardous substances in to the environment. This Site is a Tennessee Superfund site. A phased approach was planned to (1) gather existing data from previous investigations managed by the Tenn. Dept. of Environment and Conservation; (2) perform a preliminary RI, including risk assessments, and an FS with existing data to identify areas where remedial action may be necessary; (3) gather additional field data to adequately define the nature and extent of risk-based contaminants that present identifiable threats to human and/or ecological receptors; and (4) develop remedial action alternatives to reduce risks to ...
The authors have identified a protein present only in erythroid cells that binds to two adjacent sites within an enhancer region of the chicken {beta}-globin locus. Mutation of the sites, so that binding by the factor can no longer be detected in vitro, leads to a loss of enhancing ability, assayed by transient expression in primary erythrocytes. Binding sites for the erythroid-specific factor (Eryf1) are found within regulatory regions for all chicken globin genes. A strong Eryf1 binding site is also present within the enhancer of at least one human globin gene, and proteins from human erythroid cells (but not HeLa cells) bind to both the chicken and the human sites.
The ammoxidation of propane over VSb{sub y}O{sub x} catalysts (y=1, 2, 5) was investigated with respect to the role of different oxygen species in the selective and non selective reaction steps using transient experiments in the Temporal Analysis of Products (TAP) reactor. Only lattice oxygen is involved in the oxidation reactions. Using isotopic labelled oxygen it is shown that two different active sites exist on the surface. On site A, which can be reoxidized faster by gas phase oxygen compared to site B, mainly CO is formed. On site B CO{sub 2} and acrolein as well as NO and N{sub 2}O in the presence of ammonia in the feed gas are formed and reoxidation mainly occurs with bulk lattice oxygen. (orig.)
(Boiling site densities and heat-transfer coefficients have been measured for ethanol-water and ethanol-benzene mixtures at 1.01 bar for a heated vertical brass disk. A strong effect of composition on the boiling site density was observed, which was attributed to the nature of the activation of the boiling surface and mass diffusion effects. The boiling heat-transfer coefficient was found to decrease with increasin subcooling, but for the mixtures at a given level of subcooling the decrease was less than that for the single components and azeotropic mixtures.) The heat-transfer coefficient at a given heat flux was seen to be quite insensitive to the very large increase in boiling site density in comparing the pure water and the ethanol-water azeotrope results, leading one to question pool boiling models that predict heat-transfer rates on the basis of boiling site density.
Methylation of the DNA bases in the Watson-Crick GC and AT base pairs by the methyldiazonium ion was investigated employing density functional and second order Moller-Plesset (MP2) perturbation theories. Methylation at the N3, N7 and O6 sites of guanine, N1, N3 and N7 sites of adenine, O2 and N3 sites of cytosine and the O2 and O4 sites of thymine were considered. The computed reactivities for methylation follow the order N7(guanine)>N3(adenine)>O6(guanine) which is in agreement with experiment. The base pairing in DNA is found to play a significant role with regard to reactivities of the different sites.
The Detartment of Energy's National Solar Data Program established solar energy systems in residential and commercial buildings across the United States. These solar sites are linked to Vitro Laboratories Division's computer in the National Solar Data Network (NSDN). Vitro collects and analyzes data from this network to determine the thermal performance of each of the solar systems. Environmental information collected at the sites for the month of August 1980 is presented. The environmental data for the NSDN are presented in the form of tables for each solar site. The solar sites are grouped into 12 zones, each of which consists of several adjacent states. The solar energy sites are in alphabetical sequence within each zone. The tables provide available meteorological data for reporting sites in the NSDN as follows: (1) Insolation: the ...
Guidelines for uranium residual radioactive material in soil were derived for the B&T Metals Company site in Columbus, Ohio. This site has been identified for remedial action under the US Department of Energy`s (DOE`s) Formerly Utilized Sites Remedial Action Program (FUSRAP). Single-nuclide and total-uranium guidelines were derived on the basis of the requirement that following remedial action, the 50-year committed effective dose equivalent to a hypothetical individual living or working in the immediate vicinity of the site should not exceed a dose constraint of 30 mrem/yr for the current use and likely future use scenarios or a dose limit of 100 n-mrem/yr for less likely future use scenarios. The DOE residual radioactive material guideline computer code, RESRAD, was used in this evaluation. RESRAD implements the methodology described in the DOE manual for establishing residual radioactive material ...
This report describes the selection of candidate surface mining sites for the development of oil shale resources in the western United States. The purpose of this study is to input the various scenarios into an economic mine model developed for underground oil shale mines in an earlier project. Site selection was a three-phase effort. Phase I consisted of a thorough review of available resource data, which resulted in a definition of surface mineable areas. Phase II was a detailed investigation of the regions identified in the initial phase. The end result of this task was a list of potential sites having favorable overburden, grade, shale thickness, and topography values. Phase III identified those sites from which a wide range of site specific parameters can be obtained for mine design and model testing purposes. This report describes the procedures used to obtain the candidate ...
The Baird and McGuire site is a former chemical manufacturing facility in northwest Holbrook, Massachusetts, approximately 14 miles south of Boston. From 1912 to 1983 the company operated a chemical manufacturing and batching facility on the property. Manufactured products included herbicides, pesticides, disinfectants, soaps, floor waxes and solvents. Waste disposal methods at the site included direct discharge into the soil, nearby brook and wetlands, and a former gravel pit (now covered) in the eastern portion of the site. EPA conducted a removal action at the site in 1983 after a waste lagoon overflowed spreading contaminants into the Cochato River. The company ceased operating shortly thereafter. A second removal action was conducted in 1985, following the discovery of dioxin in site soils. EPA also conducted an Initial Remedial Measure at the site from ...
This paper presents a case study of site characterization and hydrocarbon contamination plume mapping/delineation in a gas processing plant in southern Mexico. The paper describes innovative and cost-effective use of passive (non-intrusive) and active (intrusive) techniques, including the use of compound-specific analytical methods for site characterization. The techniques used, on a demonstrative basis, include geophysical, geochemical, and borehole drilling. Geochemical techniques used to delineate the horizontal extent of hydrocarbon contamination at the site include soil gas surveys. The borehole drilling technique used to assess the vertical extent of contamination and confirm geophysical and geochemical data combines conventional hollow-stem auguring with direct push-probe using Geoprobe. Compound-specific analytical methods, such as hydrocarbon fingerprinting and a modified method for gasoline range organics, ...
Consideration of the technical feasibility of Yucca Mountain in Nevada as the site for a high-level nuclear waste repository has led to an intense debate regarding the economic, social, and political impacts of the repository. Impediments to the siting process mean that the nuclear waste problem is being resolved by adhering to the status quo, in which nuclear waste is stored at scattered sites near major population centers. To assess the merits of alternative siting strategies--including both the permanent repository and the status quo- we consider the variables that would be included in a model designed to select (1) the optimal number of disposal facilities, (2) the types of facilities (e.g., permanent repository or monitored retrievable facility), and (3) the geographic location of storage sites. The objective function in the model is an all-inclusive measure of social cost. The ...
This report describes the conclusion of a two-part programme, begun in 1994 with the overall aim of assisting in the development of an acceptable public participation strategy for use in Sweden for the siting of contentious facilities, with particular reference to the ongoing siting programme for a deep repository for spent nuclear fuel. The first part of the work programme, a global review of siting practice, was reported as SSI Rapport 94-15, in November 1994. This recommended further detailed studies of at least two individual programmes, which have now been carried out in Canada and the United States, and are reported on here. They involved face to face meetings with many of the main stake holders in the two programmes and enabled valuable insight to be gained into the potential problems associated with increased public participation, as well as identifying good practice where it exists. The lessons learned have then ...
Although the subtrate binding properties of adenylate kinase (AK) have been studied extensively by various biochemical and biophysical techniques, it remains controversial whether uncomplexed adenosine 5'-triphosphate (ATP) binds to the adenosine 5'-monophosphate (AMP) site of AK. The authors present two sets of experiments which argue against binding of ATP to the AMP site. (a) /sup 31/P nuclear magnetic resonance titration of ATP with AK indicated a 1:1 stoichiometry on the basis of changes in coupling constants and line widths. This ruled out binding of ATP to both sites. (b) ATP and MgATP were found to behave similarly by protecting AK from spontaneous inactivation while AMP showed only a small degree of protection. Such inactivation could also be protected or reversed by dithioerythritol and is most likely due to oxidation of sulfhydryl groups, one of which (cysteine-25) is located near the MgATP ...
The Fluxnet synthesis dataset originally compiled for the La Thuile workshop contained approximately 600 site years. Since the workshop, several additional site years have been added and the dataset now contains over 920 site years from over 240 sites. A data refresh update is expected to increase those numbers in the next few months. The ancillary data describing the sites continues to evolve as well. There are on the order of 120 site contacts and 60proposals have been approved to use thedata. These proposals involve around 120 researchers. The size and complexity of the dataset and collaboration has led to a new approach to providing access to the data and collaboration support and the support team attended the workshop and worked closely with the attendees and the Fluxnet project office to define the requirements for the support infrastructure. As a result ...
Porous carbon with high surface area and pore volume was prepared by a reverse replication process and its toluene equilibrium adsorption behavior was investigated. The preparation process of the porous carbon was composed of following sub-processes in series: synthesis and template preparation of silica gel, impregnation and polymerization of DVB monomer in silica template, carbonization of DVB polymer in a silica-polymer composite, and HF-assisted selective etching of silica in carbon-silica composite, The prepared porous carbon was nano porous and had ultrahigh specific surface area (2007 m{sup 2}/g) and large pore volume (3.07cm{sup 3}/g). The nanoporous carbon showed rapid toluene adsorption rate and good toluene adsorption capacity, compared with a commercial Y-type zeolite, In the present study, a reverse replication process to prepare nanoporous carbons will be introduced and its application potential as a gas adsorbent will be ...
There has been considerable interest in producing and studying nanoparticle materials because of the effect of size on their structure, physical and chemical structure. Most studied nanoparticle semiconductors belong to the II-VI group, as they are relatively easy to synthesize and are generally prepared as particulates or in thin film form. Among II-VI compounds, CdS is one of the most studied materials. There are different ways to synthesize CdS nanoparticles such as colloidal particles, chemical decomposition, sol-gel, gas evaporation, magnetron sputtering, electrostatic deposition, and etc. {gamma}-irradiation is one of the effective methods for synthesis of nanomaterials. These nonomaterials have been extensively used in the preparation of nanocrystalline metals, metal oxides, and metal-polymer composites. However, The preparation of CdS nanoparticle and CdS/ polyacrylonitrile nanocomposite by {gamma}-irradiation method at room temperature and ambient ...
Propylene polymerizations were carried out with {phi}{sub 2}C(Flu)(Cp)ZrCl{sub 2} and SiMe{sub 2}(Ind)2ZrCl{sub 2} catalysts supported on silica, zeolite sodic mordenite (NaM) and acid mordenite (HM). The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]). The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f{sub 2}C(Flu)(Cp)ZrCl{sub 2}, SiO{sub 2} and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereo regularity. (author)
Propylene polymerizations were carried out with #phi#_2C(Flu)(Cp)ZrCl_2 and SiMe_2(Ind)2ZrCl_2 catalysts supported on silica, zeolite sodic mordenite (NaM) and acid mordenite (HM). The polymerizations were performed at different temperatures and varying aluminium/zirconium molar ratios ([Al]/[Zr]). The effect of these reaction parameters on the catalyst activity was investigated using a proposed statistical experimental planning. In the case of f_2C(Flu)(Cp)ZrCl_2, SiO_2 and NaM were used as support and the catalyst performance evaluated using toluene and pentane as polymerization solvent. The molecular weight, molecular weight distribution, melting point and crystallinity of the polymers were examined. The results indicate very high activities for the syndiospecific heterogeneous system. Also, the polymers obtained had superior Mw and stereo regularity. (author)
This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of clay. It was observed that both macroporosity and pore size distribution were beneficially modified after blend compatibilisation. Final GDL conductivity of ...
The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing methane, use of hygroscopic filters to remove trace water and ...
One of the most challenging topics in the area of organic electronic devices is the growth of transparent electrodes onto flexible polymeric substrates that will be characterized by enhanced conductivity in combination with high optical transparency. An essential aspect for these materials is their synthesis and/or microstructure which define the transparency, the stability and the interfacial chemistry which in turn determine the performance and stability of the organic electronic devices, such as organic light emitting diodes, organic photovoltaics, etc. In this work, we will discuss the latest advances in the growth of organic (e.g. PEDOT:PSS) and inorganic (e.g. zinc oxide-ZnO, indium tin oxide-ITO) conductive materials and their deposition onto flexible polymeric substrates. We will compare the optical, structural, nano-mechanical and nano-topographical properties of the inorganic and organic materials and we investigate the effect of their structure on their properties and ...
The deposition of platinum on various carbon blacks was carried out by forming active functional groups on the surface of the carbon support, and exchanging these active groups with different platinum complexes. Using H{sub 2}PtCl{sub 6} solution, an impregnation rather than an exchange takes place. However, using divalent platinum complexes [Pt(NH{sub 3}){sub 4}]{sup 2+}, a fast exchange takes place which leads to extremely small platinum particles highly dispersed on the surface of carbon black. A comparison of the catalytic activities of platinum supported on various carbon blacks was also carried out. The performances of PEFC (Polymer Electrolyte Fuel Cell) based on the process of the ion exchange are reported. (authors) 3 refs.
Coded imaging techniques using thick, micro-Fresnel zone plates as coded apertures have been used to image x-ray emissions (2-20 keV) and 3.5 MeV Alpha particle emissions from laser driven micro-implosions. Image resolution in these experiments was 3-8 ..mu..m. Extension of this coded imaging capability to higher energy x-rays (approx. 100 keV) and more penetrating charged particles (e.g. approx. 15 MeV protons) requires the fabrication of very thick (50-200 ..mu..m), high aspect ratio (10:1), gold Fresnel zone plates with narrow linewidths (5-25 ..mu..m) for use as coded aperatures. A reactive ion etch technique in oxygen has been used to produce thick zone plate patterns in polymer films. The polymer patterns serve as electroplating molds for the subsequent fabrication of the free-standing gold zone plate structures.
Coded imaging techniques using thick, micro-Fresnel zone plates as coded apertures have been used to image x-ray emission (2--20 keV) and 3.5 MeV Alpha particle emissions from laser driven micro-implosions. Image resolution in these experiments was 3--8 ..mu..m. Extension of this coded imaging capability to higher energy x rays (approx.100 KeV) and more penetrating charged particles (e.g., approx.15 MeV protons) requires the fabrication of very thick (50--200 ..mu..m), high aspect ratio (10:1), gold Fresnel zone plates with narrow linewidths (5--25 ..mu..m) for use as coded apertures. A reactive ion etch technique in oxygen has been used to produce thick zone plate patterns in polymer films. The polymer patterns serve as electroplating molds for the subsequent fabrication of the free-standing gold zone plate structures.
We are attempting to characterize and model the micromechanical response of highly-filled polymers. In this class of materials, the continuous plastic binder used to bond the highly-filled material dominates the observed viscoelastic response. As a result, realistic lifetime analysis of these materials will require a thorough understanding of the contribution of the plastic binder. Laboratory applications of these materials include plastic bonded explosives, propellants, a variety of specialized filled organic materials for stockpile systems, and highly filled epoxy dielectric materials for the National Ignition Facility. We have explored numerous techniques to characterize the local microstructure of plastic bonded explosives. However, insufficient funding was obtained to bring these technologies to maturity, nevertheless our present tool set is significantly better than 2 years ago. We have also made some progress in developing an appropriate micromechanical ...
Some kind of one-dimensional (1D) peanut-shaped fullerene polymers (PSFPs) exhibit metallic properties, but their occurrence conditions are not yet clarified. By using the VASP (Vienna ab-initio simulation package) with density functional theory (DFT) and projector augmented wave (PAW) method, we have performed first-principles electronic structure calculations of four basic 1D PSFPs, T1, T2, T6, and T7 (the name of T1-T6 is the same as that of Wang et al. [9]) and two associated 1D PSFPs, T1SW1 and T6SW that are created by generalized Stone-Wales transformation (GSW) from T1 and T6. We found that almost regular six-membered rings connected throughout the tube are necessary to get metallic properties for the 1D PSFPs, although there may be several other conditions to expect metallic proper...
An extruder used by kneading stearic acid (St acid) into it for the production of polystyrene for injection molding was studied. Most disadvantageous of kneading methods, melt-feed method, was applied because this method enables the utilization of existing facilities. St acid is discolored when the temperature surpasses 270{sup 0}C in nitrogen atmosphere, and the contact with metals intensifies the discoloring. The discoloring is more intensified by the contact with nitriding steel than with stainless steel. Residence time is 85 seconds, and even the contact with nitriding steel does not discolor ST acid when the temperature is lower than 270{sup 0}C. In the melt-feed method, when the die is in a bad shape, it brings about dead space at the tip of the die and St acid holds up there. When the kneading is in bad condition (St acid and polymer are hard to mix because their viscosities are quite different), St acid gathers between the barrel wall and the ...
The effects of gas diffusion layer's (GDL's) anisotropic bending stiffness on the degradation behavior of polymer electrolyte membrane fuel cells have been investigated under freezing conditions. We have prepared GDL sheet samples such that the higher stiffness direction of GDL roll is aligned with the major flow field direction of a metallic bipolar plate at angles of 0^o (parallel: '0^o GDL') and 90^o (perpendicular: '90^o GDL'). The I-V performances before and after 1000 temperature cycles between -10 and 1 ^oC of 90^o GDL stack are higher than those of 0^o GDL stack, and the voltages of 90^o GDL stack are decreased slower than those of 0^o GDL stack, indicating a higher durability of 90^o GDL stack. Furthermore, the values and increasing rates of high-frequency resistance of 90^o GDL s...
Electrospun nanofibers composed of biodegradable polymers are attractive candidates for cell culture scaffolds in tissue engineering. Their fine-meshed structures, resembling natural extracellular matrices, effectively interact with cell surfaces and promote cell proliferation. The application of electrospinning, however, is limited to two-dimensional (2D) or single tube-like scaffolds, and the fabrication of arbitrary three-dimensional (3D) scaffolds from electrospun nanofibers is still very difficult due to the fibers' continuous and entangled form. To address this issue, in this paper, we describe the use of phase-separation-assisted electrospray and electrostatic focusing to perform continuous direct 3D patterning of nanofibrous microcapsules of biodegradable polylactic acid (PLA). These microcapsules exhibit fiber-particle duality because they are composed of nanofibers suitable for cell attachment while also being easy to handle as particles for direct 3D ...
A solar water splitting cell composed of WO3, Polymer Electrolyte Membrane (PEM) and Pt was constructed for producing hydrogen from deionized water in sunlight. Spectral responsivity measurements under various temperatures and bias voltages were conducted for the cell using the Incident Photon to Current Efficiency (IPCE) method. For comparison, a known WO3 Photo Electro Chemical (PEC) cell containing H3PO4 electrolyte, WO3/H3PO4/Pt, was tested using the same test method. The WO3/PEM-H2O/Pt cell showed better Quantum Efficiency (QE) performance compared to that obtained from the cell with the chemical electrolyte. For the first time, spectral responsivity of photo water splitting process without bias power was unveiled in the new WO3 cell, demonstrating the self-sustained photo electrolysi...
Phillips Petroleum Company recently completed a microbial selective plugging (MSP) pilot at the North Burbank Unit (NBU), Shidler, Oklahoma. Nutrients were selected for the pilot that could stimulate indigenous microflora in the reservoir brine to grow and produce exopolymer. It was found that soluble corn starch polymers (e.g., maltodextrins) stimulated the indigenous bacteria to produce exopolymer, whereas simple sugars (e.g., glucose and sucrose), as well as complex media (e.g., molasses and Nutrient Broth), did not. Injection of maltodextrin into rock cores in the presence of indigenous NBU bacteria resulted in stable permeability reductions (> 90%) across the entire length, while injection of glucose resulted only in face plugging. In addition, it was found that organic phosphate esters (OPE) served as a preferable source of phosphorus for the indigenous bacteria, since orthophosphates and condensed phosphates precipitated in NBU brine at reservoir ...
The need for a hydrogen economy is driven by increasing fuel prices, depleting oil reserves and uncertainty over supplies, and concerns about global warming and environmental pollution. Alternative methods to portable energy sources such as fossil fuels are being developed that are more efficient and carbon-emission-neutral. A prospective method is to produce hydrogen as an energy carrier. This paper presented a study on the degradation of materials under conditions of the sulphur-iodine (SI) thermochemical cycle. The paper provided background information on the study and presented a schematic of the SI cycle. A literature review was presented along with materials selected, such as refractory metals, reactive metals, superalloys, glassy metals, ceramics, cermets, polymers, composites, and coatings. The experimental method was then described. A capsule method was developed to rapidly quantify the decomposition rate of the candidate materials under the target ...
This report aims to address the potential for solid polymer fuel cell (SPFC) systems to be successfully exploited in the combined heat and power (CHP) market. A number of market studies have been undertaken to look at the size and future potential for this CHP market as well as such issues as market forces and geographical locations. This study focuses on a different aspect, that of the technical and commercial requirement together with the development needs. In order to understand how an SPFC system will have to perform, it is first necessary to examine the criteria used to judge the commercial merits of a particular CHP scheme. Issues that must be addressed include: the investment criteria - time to pay back the investment or rate of return on the investment; the influence of external factors such as electricity cost tariffs, fuel price and regulatory requirements; the cost and performance of existing technology; and the influence of the energy demand profile of ...
Solid-state nuclear magnetic resonance (NMR) has been used to explore the nanometer-scale structure of Nafion, the widely used fuel cell membrane, and its composites. We have shown that solid-state NMR can characterize chemical structure and composition, domain size and morphology, internuclear distances, molecular dynamics, etc. The newly-developed water channel model of Nafion has been confirmed, and important characteristic length-scales established. Nafion-based organic and inorganic composites with special properties have also been characterized and their structures elucidated. The morphology of Nafion varies with hydration level, and is reflected in the changes in surface-to-volume (S/V) ratio of the polymer obtained by small-angle X-ray scattering (SAXS). The S/V ratios of different Nafion models have been evaluated numerically. It has been found that only the water channel model gives the measured S/V ratios in the normal hydration range of a working fuel ...
Lithium, with its strong reducing property and very low potential (-3.045 V/ENH), is one of the best material for electrodes. By combining lithium with an oxidizer, one can obtain an energy and electromotive force higher than with any other electrochemical couple. The density of lithium is low (0.534 g/cm{sup 3}) and thus, its specific capacity is higher than other classical anode materials. This article presents the technology of lithium batteries: 1 - presentation; 2 - negative electrodes: metallic lithium based, lithiated carbon based, transition metal compounds based negative electrodes; 3 - positive electrodes: 'low' voltage and 'high' voltage cathode materials; 4 - electrolytes: introduction, organic solvents and lithium salts-based electrolytes (case of the lithium anode battery, case of the lithium-ion battery), polymer electrolytes; 5 - metallic lithium anode and liquid electrolyte batteries: first realizations, safety ...
Polyacrylonitrile (PAN)-based polymer electrolytes have obtained considerable attention due to their fascinating characteristics such as appreciable ionic conductivity at ambient temperatures and mechanical stability. This study is based on the system PAN-ethylene carbonate (EC)-propylene carbonate (PC)-lithium trifluoromethanesulfonate (LiCF3SO3). The composition 15 mol% PAN-42 mol% EC-36 mol% PC-7 mol% LiCF3SO3 has shown a maximum room temperature conductivity of 1.2 x 10(-3) stop S cm(-1) stop. Also, it was possible to make a thin, transparent film out of that composition. Cells of the form, Li/PAN-EC-PC-LiCF3SO3/polypyrrole (PPy)-alkylsulfonate (AS) were investigated using cyclic voltammetry and continuous charge-discharge tests. When cycled at low scan rates, a higher capacity could be obtained and well-defined peaks were present. The appearance of peaks elucidates the fact that redox reactions occur completely. This well proves the reason for higher capacity. ...
Abstract BACKGROUND: Nitrate leaching and the resulting groundwater contamination from intensive cereal production has become a major concern for long-term farmland efficiency and environmental sustainability in northern China. The aim of this study was to evaluate a water-saving super-absorbent polymer (SAP) for minimising NO3- leaching from soil and optimising corn growth and yield. Thirty-six undisturbed soil lysimeters were installed in a field lysimeter facility in drought-affected northern China to study the growth and yield characteristics of summer corn (Zea mays L.) as well as the amount of NO3-leaching losses under different fertiliser (standard, medium or 75% and low, or 50% of conventional fertilisation rate) and SAP (control, 0; level-1, 15 kg ha-1 and level-2, 30 kg ha-1) tre...
The spontaneous ionic polymerization of 4-vinyl-pyridine in presence of mono-tosylated or bromated short chains of poly(ethylene oxide)-(PEO) is used to prepare amorphous comb-like poly-cations with low Tg. The polymer electrolyte properties of these new structures have been studied without any addition of salts. The ionic conductivity of these fixed cation poly-electrolytes depends on the length of the grafted PEO and varies from 10{sup -7} to 10{sup -4} S/cm between 25 and 80 deg. C. It is only weakly dependent on the nature of the cation but it is controlled by the movements of the pyridinium cation which are facilitated by the plastifying effect of the POE chains which do not directly participate to the ionic transport. (J.S.) 17 refs.
Concerning high performance composite solid propellant BAMO and BAMO-based copolymers, synthetic method and properties of them were studied. Comparison graph of theoretical specific impulse for various propellants were shown, by that, reason why highest specific impulse BAMO was selected as direction of the study. As the orientation of synthesis, those were indicated that radicals at both ends should be hydroxyl so as urethane bonding was available, that liquid at normal temperature was required for easy handling, and that glass transition temperature is required to be low enough. Synthesis was conducted by ring-opening polymerization of ring ether detail procedures of which were explained. Measurements of properties was performed for thermochemical properties, thermal decomposition, combution heat, and friction sensitivity test to confirm safety. As the result, those were understood that thermal decomposition was divided into two phases, rapid exothermal decomposition as initial phase ...
It has been prepared composites materials by means of monomer penetration in pores of wood samples and later curing by means of gamma irradiation. The studied species were Hura crepitans L. (catahua), Aniba puchury-minor (C. Martinez) (mohena amarilla), and Calycophyllum spruceanum (Benth.) (capirona). These new materials exhibit smaller water absorption and better mechanical properties in comparison with native wood. The test tubes of catahua treated with the styrene-polyester mixture absorb only up to 10% humidity compared to the native species whereas its hardness is increased in a 100%. (author).
Wood plastic composite (WPC) has been prepared with a low grade wood simul (Salmalia malabarica) of Bangladesh under Co-60 gamma irradiation using MMA as the bulk monomer combined with methanol as the swelling solvent at different urea concentrations. Effect of a second solute such as NVP, TPGDA and TMPTA in the impregnating solution is evaluated. NVP appears to be the best co-additive/second solute among all the additives used to yield the composite with the highest polymer loading (PL) and tensile strength (TS) at 0.5% urea concentration. (author).
Wood plastic composite (WPC) has been prepared with a low grade wood simul (Salmalia malabarica) of Bangladesh under Co-60 gamma irradiation using MMA as the bulk monomer combined with methanol as the swelling solvent at different urea concentrations. Effect of a second solute such as NVP, TPGDA and TMPTA in the impregnating solution is evaluated. NVP appears to be the best co-additive/second solute among all the additives used to yield the composite with the highest polymer loading (PL) and tensile strength (TS) at 0.5% urea concentration. (author).
The thermal degradation and crystallisation behaviours of polyamide12/isotactic polypropylene (PA12/PP) blends were studied. Effects of blend ratio and compatibiliser concentration on the thermal degradation properties of the blends were analysed. The activation energy for degradation in compatibilised and uncompatibilised blends computed using Horowitz-Metzger equation was reported. The blend ratio as well as the presence of compatibiliser has significant effect on the thermal stability of the blends. Phase morphology was found to be one of the decisive factors that affected the thermal stability of both uncompatibilised and compatibilised blends. Melting and crystallisation behaviours of the blends in the presence and absence of compatibiliser were evaluated. It was observed that blendin...
Gasification experiments were performed using urban waste wood (Altholz) with additions of polymers typical for separately collected waste plastics. The resulting tar product distributions are discussed in this paper. The amount of tars is shown to be a function of operation parameters of the gasifier as well as the fuel. Plastics admixture yields higher concentrations of aromatic tar compounds in the gases, even if the plastic used is not aromatic in its structure. Such mixtures can be gasified for the production of synthesis gas, but clearly a larger effort will be required in cleaning the gases. (author)
We report tests of a refuelable zinc/air battery of modular, bipolar-cell design, intended for fleet electric busses and vans. The stack consists of twelve 250-cm{sup 2} cells built of two units: (1) a copper-clad glass-reinforced epoxy board supporting anode and cathode current collectors, and (2) polymer frame providing for air- and electrolyte distribution and zinc fuel storage. The stack was refueled in 4 min. by a hydraulic transfer of zinc particles entrained in solution flow.
The objectives of this project were to develop feasible synthetic routes to produce (1) 4(4{prime}-hydroxy-5{prime}6{prime},7{prime}8{prime}-tetrahydro-1{prime}-naphthylmethyl)-6-methyldibenzothiophene, and (2) a 1-hydroxynaphthalene-dibenzothiophene polymer. These compounds are thought to be representative of sulfur containing molecules in coal. The program was divided into two technical tasks. Unfortunately, the attempted syntheses of these compounds was unsuccessful due to their unusual reactivities. Attempted synthetic routes and possible future routes are described, and Appendix A lists the compounds that were synthesized during this program.
Wood plastic composites formation has been studied with simul (soft wood, density = 0.4 g/cm{sup 3}) and butylmethacrylate (BA) monomer using 10% methanol as the swelling agent. The effect of additives like sulfuric acid, multifunctional monomers (NVP, TPGDA, TMPTA) and oligomers (PEA, UA and EA) has been investigated using 1-3 Mrad dose at 0.8 Mrad/h. Synergistic polymer yields have been achieved in presence of the additives. The tensile properties of the composite are also reported. (author).
Enhanced recovery by chemical flooding using surfactant and/or polymers simultaneously implies the following: (1) a fundamental knowledge of the physical chemistry of micellar systems and interfaces; (2) the proper formulation of mathematic models handling the basic mechanisms of oil recovery; and (3) the use of field-scale pilot units to test the validity of the models and to acquire technical knowledge. Efforts have been made by the French in these directions, and the main results are described. Special attention is paid to the search for new products and the improvement of manufacturing processes. 10 references.
One of the greatest opportunities for using of biomass as a precursor in the production of polymeric materials is the lignocellulose composites that can combine high performance with low costs. This work is a initial study on the production of a lignocellulose reinforced polyethylene composite. A compatibilization made by a induced gamma radiation grafting reaction was used to increase the adhesion between the matrix and the reinforced or filled fibers. The lignocellulose materials were exposed to gamma radiation in order to promote a molecular degradation and increase its reactivity. The polymer, the lignocellulose material and the compatibilization were processed by extrusion and the composite produced by this process were characterized by mechanical tests. (author)
Research activity during the 1991--1992 funding period has been concerned with the following topics relevant to carbon monoxide activation. (1) Exploratory studies of water gas shift catalysts heterogenized on polystyrene based polymers. (2) Mechanistic investigation of the nucleophilic activation of CO in metal carbonyl clusters. (3) Application of fast reaction techniques to prepare and to investigate reactive organometallic intermediates relevant to the activation of hydrocarbons toward carbonylation and to the formation of carbon-carbon bonds via the migratory insertion of CO into metal alkyl bonds.
Research activity during the 1991--1992 funding period has been concerned with the following topics relevant to carbon monoxide activation. (1) Exploratory studies of water gas shift catalysts heterogenized on polystyrene based polymers. (2) Mechanistic investigation of the nucleophilic activation of CO in metal carbonyl clusters. (3) Application of fast reaction techniques to prepare and to investigate reactive organometallic intermediates relevant to the activation of hydrocarbons toward carbonylation and to the formation of carbon-carbon bonds via the migratory insertion of CO into metal alkyl bonds.
A solid electrolyte cell comprises an alkali metal anode, e.g. lithium, a halogen-containing organic polymer cathode and a solid elecrolyte between the anode and the cathode. The cathode comprises iodine-containing vacuum-cyclised polyacrylonitrile, and the solid electrolyte is preferably lithium iodide and halogen-free vacuum-cyclised polyacrylonitrile. This patent also discloses the use of isotactic polyacrylonitrile, a method of making a cathode comprising iodine-containing vacuum-cyclised polyacrylonitrile, and novel methods of making the solid elecrolyte cells described.
The doping of deuterated polyparaphenylene (C/sub 6/D/sub 4/)sub(n) with AsF/sub 5/ has been investigated by real time neutron diffractometry at 100, 400 and 820 mbar AsF/sub 5/ pressure. The reaction appears to be diffusion controlled. Evidence for one doped phase with partial crystalline order was obtained. Structural considerations suggest two polymer chains plus one dopant ''string'' as the repetitive unit.
Polymer electrolyte membrane fuel cells (PEMFCs) are energy conversion devices that produce electricity from a supply of fuel, such as hydrogen. One of the major challenges in achieving efficient energy conversion is the development of cost-effective materials that can act as electrocatalysts for PEMFCs. In this letter, we demonstrate that, instead of conventional noble metals, such as platinum, chromium nitride nanocrystals of fcc structure exhibit attractive catalytic activity for PEMFCs. Device testing indicates good stability of nitride nanocrystals in low temperature fuel cell operational environment.
Micron-sized Li{sub 4}Ti{sub 5}O{sub 12} was prepared in a single-step solid-state reaction involving TiO{sub 2} and Li{sub 2}CO{sub 3}, and its electrochemical behavior was evaluated in Li and Li-ion cells containing a polyacrylonitrile (PAN)-based solid polymer electrolyte. The usefulness of Li{sub 4}Ti{sub 5}O{sub 12} was demonstrated for three distinctive applications: (1) cathode of a 1.5 V rechargeable Li battery, (2) auxiliary electrode for investigating the electrochemistry of Li insertion cathode materials, and (3) anode of a Li-ion cell in conjunction with a high voltage cathode, e.g., cubic spinel LiMn{sub 2}O{sub 4}. The micron-sized Li{sub 4}Ti{sub 5}O{sub 12} exhibited a capacity of 160 mAh/g at C/20--C/30 rates which about 7% better than the capacity exhibited by this material prepared according to a previously published procedure. More importantly, the micron-sized oxide showed significantly better high rate capability, yielding 25--50% larger ...
In this article, a continuous stabilization process was used to make flame resistant fibers from polyacrylonitrile (PAN) fibers. The effect of the stabilization time and the stretching process during the stabilization process on the physical properties and flammability of the resultant flame resistant fibers was studied. Increased drawing of PAN fibers during the continuous stabilization process was found to decrease the diameter and increase the tensile strength in the resultant flame resistant fibers. These fibers also had higher density. There were no absolute relationships seen between flame-resistance and the formation of stable ladder polymers, density, and oxygen content. ((orig.))
Several commercially available capacitors were evaluated at the liquid nitrogen temperature (77 K). Our primary interest was their performance under a bias voltage when used as DC link capacitors in cryogenic power electronics. In general, the performance of polymer capacitors and certain ceramic capacitors is almost independent of the temperature, DC bias, and frequency. On the other hand, ceramic capacitors based on high dielectric constant materials showed a strong dependence on the boundary conditions. Aluminum electrolytic capacitors showed a dramatic decrease of capacitance at 77 K, possibly due to the electrolyte being frozen and therefore losing its conductivity.
One of the major scientific and technological challenges for the production of flexible organic electronic devices is the device protection against atmospheric molecule permeation, which causes corrosion reducing its operation and lifetime. In this work, Spectroscopic Ellipsometry has been implemented to investigate the influence of silicon dioxide nanoparticles on the optical properties of hybrid polymers. The spectra analysis revealed valuable information about the electronic and vibrational response as well as the cross-linking mechanisms of these materials. The correlation of the optical properties with the synthesis parameters and the barrier response will contribute towards their optimization in order to be used as high barrier coatings for flexible organic electronics applications.
Original investigations of ablation of minerals, fullerene-like compounds, polymers and complicated biological macromolecules under the action of submillimeter radiation of the free-electron laser (FEL) developed and built at Budker Institute of Nuclear Physics [V.P. Bolotin et al., First experiments on high-power Novosibirsk terahertz free-electron laser, Budker INP, 2005, p. 37 [1
The report is divided into three sections. The first section contains a general introduction to ion exchange resins used in various processes, the second section describes characteristic properties of the polymer materials and the inter relation between them. This will, in turn, be useful to interpret the data obtained from the various tests carried out on the resins in the laboratory. In the third section of the report, are given the details of each method used for a particular test to be carried out on a routine basis. Each method describes the principle involved, the reagents and apparatus used in the experiment, the actual procedure and calculations and recording of the data. 3 refs. (author).
... Removal of this layer facilitates the unreeling of cocoons into long strands of silk comparable to those derived from the domesticated mulberry silkworm (Bombyx mori, B. mori). The research was funded in part by the SABIP ('Silks as biomimetic ideals for polymers) project, which has clinched a European Research Council (ERC) grant worth almost EUR 2.3 million under the EU's Seventh Framework Programme (FP7). Presented in the journal Biomacromolecules, the findings could lead to the development of new silk industries in ...
Those materials that can be extracted from pine or oak by ether, ethanol, methyl methacrylate (MMA), or benzene--alcohol all act as inhibitors in the #gamma# polymerization of MMA--wood composites. It was found that preirradiation of either the wood or of the wood--monomer combination reduces or eliminates the inhibitory effect. The most practical industrial solution to this problem is to increase the dose, thereby achieving high molecular polymer in the composite. However, the presence of a maximum in the molecular weight--dose curves means that each wood--monomer pair may have a different optimum dose.
Recently, a superconducting cryo-electron microscope in which specimens are cooled to the liquid helium temperature (4.2 K) has been developed. The main components and functional features of this new microscope are reported together with application data on polyethylene, poly (4-methyl-1-pentene), valonia cellulose, rock salt, ice crystallites and ceramic superconductor. The resistance to electron radiation damage, of beam-sensitive specimens including polymers has been increased more than ten times. Thus, the microscope has made it possible to take high resolution images and to analyze the crystal-structure of micro-areas. (orig.).
The carrier mobility in organic disordered materials, such as conjugated polymers, plays an important role in understanding the behaviour of organic electronic devices. We investigated the mobility of charge carriers in poly(3-hexylthiophene) (P3HT) using different current transient measurement methods. Besides the conventional transient photoconductivity experiment, time-of-flight (TOF), we used extraction current transient techniques, such as charge carrier extraction by linearly increasing voltage (CELIV), probing equilibrium carriers instead. The field and temperature dependence of the mobility are discussed in view of hopping transport in a Gaussian density of states distribution.
In this article, several applications of nanomaterials in food packaging and food safety are reviewed, including: polymer/clay nanocomposites as high barrier packaging materials, silver nanoparticles as potent antimicrobial agents, and nanosensors and nanomaterial-based assays for the detection of food-relevant analytes (gasses, small organic molecules and food-borne pathogens). In addition to covering the technical aspects of these topics, the current commercial status and understanding of health implications of these technologies are also discussed. These applications were chosen because they do not involve direct addition of nanoparticles to consumed foods, and thus are more likely to be marketed to the public in the short term.
In this work, the chemical transformations induced by 5 keV protons (10{sup 6} ion cm{sup -2}) at the surface of 0.4 {mu}m polyacrylonitrile and polymethacrylonitrile films are analysed by XPS and IRRAS. Spectroscopic changes in both the polymers are globally similar, the most significant feature being a lower relative concentration of nitrogen with respect to carbon closer to the surface. Quantitatively, this change is more marked in the case of polyacrylonitrile which suggests a direct relation with the hydrogen in {alpha} to the nitrile function.
The Maybell uranium mill tailings site is 25 miles (mi) (40 kilometers [km]) west of the town of Craig, Colorado, in Moffat County, in the northwestern part of the state. The unincorporated town of Maybell is 5 road mi (8 km) southwest of the site. The site is 2.5 mi (4 km) northeast of the Yampa River on relatively flat terrain broken by low, flat-topped mesas. U.S. Highway 40 runs east-west 2 mi (3.2 km) south of the site. The designated site covers approximately 110 acres (ac) (45 hectares [ha]) and consists of a concave-shaped tailings pile and rubble from the demolition of the mill buildings buried in the former mill area. The site is situated between Johnson Wash to the east and Rob Pit Mine to the west. Numerous reclaimed and unreclaimed mines are in the immediate vicinity. Aerial photographs (included at the end of this executive summary) show evidence ...
In this paper, we evaluate the performance of the 1- and 5-site models of methane on the description of adsorption on graphite surfaces and in graphitic slit pores. These models have been known to perform well in the description of the fluid-phase behavior and vapor-liquid equilibria. Their performance in adsorption is evaluated in this work for nonporous graphitized thermal carbon black, and simulation results are compared with the experimental data of Avgul and Kiselev (Chemistry and Physics of Carbon; Dekker: New York, 1970; Vol. 6, p 1). On this nonporous surface, it is found that these models perform as well on isotherms at various temperatures as they do on the experimental isosteric heat for adsorption on a graphite surface. They are then tested for their performance in predicting the adsorption isotherms in graphitic slit pores, in which we would like to explore the effect of confinement on the molecule packing. Pore widths of 10 and 20 A are chosen in this ...
A transplant experiment was conducted to determine whether standard metabolic rate (SMR) of a freshwater shrimp (Palaeomonetes paludosus) would be affected by exposure to trace element-enriched coal combustion waste (coal ash). Shrimp were transplanted into replicate cages in a coal ash-polluted site and a reference site for 8 months. The coal ash-polluted site was characterized by elevated sediment concentrations of As, Cd, Cr, Cu, Ni, Pb and Se compared to sediments in the reference site. After 8 months in the study sites, shrimp in the polluted site appeared to have accumulated As, Cd and Se from the habitat, but there were on differences in survival between the study sites. However, mean SMR of shrimp (measured as O{sub 2} consumption at rest) held in the polluted site was 51% higher than mean SMR of shrimp held in ...
Raman scattering was observed from thin film optical waveguides of cellulose acetate exposed to water vapor from 0% to 100% relative humidity (RH), and from dilute solutions of water in methyl acetate. Spectra of cellulose acetate (CA398, 39.8% acetyl) at low RH and cellulose triacetate (CTA) at low and high RH are consistent with the presence of water monomers that are weakly hydrogen bonded to acetyl C=O groups. Differences between the spectra of water in CA398 and CTA at low RH are attributed to sequential hydrogen bonding involving OH groups in CA398. At high RH, CA398 and CTA (to a lesser extent) show bands attributed to water/water interactions that are similar to those found in sequentially hydrogen-bonded hydrates. CA398 films that are annealed at high temperatures exhibit decreased water/water interactions at high RH. Exposure of CA398 films to D/sub 2/O converts > 90% of all polymer OH groups to OD groups. This indicates that water is accessible to ...
The anodic reaction kinetics and interfacial mass transport of a direct polymer electrolyte membrane formic acid fuel cell have been investigated in an all solid-state electrochemical cell using a highly active nanostructured palladium-gold alloy microelectrode as an in situ probe. Well-defined 'S-shaped' steady-state cyclic voltammograms exhibiting current-rising region at lower overpotentials and limiting current region at higher overpotentials have been first obtained for the electrochemical oxidation of formic acid at varying temperature. The 'S-shaped' steady state polarization curves and chronoamperometric curves enable convenient measurements of the anodic reaction kinetics and interfacial mass transport of formic acid under real polymer electrolyte membrane conditions. It is encouragingly found that formic acid can be directly oxidized to CO2 with the first electron transfer being the likely rate-determining step and the formation of ...
Thin films (1-10 ?m thickness) of nanocomposites (NC) based on organic coordinated compound (OCC) Eu(TTA)2(Ph3PO)2NO3 (where TTA is thenoyl trifluoroacetonate (C8H5F3O2S), Ph3PO - triphenylphosphine (C6H5PO) and polymer-polyvinylpyrrolidone ((C6H9NO)n) (PVP)) were obtained by chemical methods and with different molar ratios into organic polymer matrix. NC have been characterized by measurements of optical transmission, excitation spectra of photoluminescence (PL) and photoluminescence of NC at different concentrations of Eu(TTA)2(Ph3PO)2NO3 in NC. In the optical transmission of NC, the characteristic parameters of NC such as threshold absorbance, dependence on the concentration of the organic coordinated compound in NC, etc., have been determined The displacement of threshold absorption to infrared is observed with increasing of the concentration of the coordination material in NC. The excitation spectrum of photoluminescence of NC led the ...
A necessary condition for crevice corrosion is that a crevice former create a sufficiently tight, restricted geometry on the metal surface to support the development of critical crevice chemistry. Crevice corrosion is affected by the crevice geometry (tightness) and the properties of the crevice former. The objective of this study is to determine the effect of the crevice former material on the evolution of localized corrosion-damage. A standard crevice corrosion test method is modified by (a) the use of ceramic, metal or polymer materials as the crevice former and (b) the variation of size and shape of the crevice. This study focuses on the post initiation stage of crevice corrosion and addresses factors that may limit the initiation of localized corrosion and also slow or stop the continued propagation of corrosion. Controlled crevice corrosion tests are performed under aggressive, accelerated conditions on Ni-Cr-Mo alloy C-22 and other alloys for comparison. ...
Magnetic properties of the Al1-xGaxFeO3 family of oxides crystallizing in a non-centrosymmetric space group have been investigated in detail along with structural aspects by employing X-ray and neutron diffraction, Moessbauer spectroscopy and other techniques. The study has revealed the occurrence of several interesting features related to unit cell parameters, site disorder and ionic size. Using first-principles density functional theory based calculations, we have attempted to understand how magnetic ordering and related properties in these oxides depend sensitively on disorder at the cation site. The origin and tendency of cations to disorder and the associated properties are traced to the local structure and ionic sizes. -- Graphical abstract: We have studied both experimentally and theoretically the important role of disorder at the cation site on magnetic and related properties of the Al1-xGaxFeO3 family of oxides ...
A method to control charge transfer reaction in DNA using hybrid nanometer-sized TiO{sub 2} nanoparticles was developed. In this system extended charge separation reflects the sequence of DNA and was measured using metallic silver deposition or by photocurrent response. Light-induced extended charge separation in these systems was found to be dependent on the DNA-bridge length and sequence. The yield of photocatalytic deposition of silver was studied in systems having GG accepting sites imbedded in AT runs at varying distances from the TiO{sub 2} nanoparticle surface. Weak distance dependence of charge separation indicative of a hole hopping through mediating adenine (A) sites was found. The quantum yield of silver deposition in the system having a GG accepting site placed 8.5 {angstrom} from the nanoparticle surface was found to be {Phi} = 0.70 (70%) and {Phi} = 0.56 (56%) for (A){sub n} and (AT){sub n/2} bridge, ...
On 30th September 1985, the Federal Government licensed site suitability investigations in three areas with a view to disposal of low-and intermediate-level radioactive waste. This report gives a summary overview of the corresponding research programme at the potential site Oberbauenstock. The first part of the report begins with some comments on the concept of radioactive waste disposal and on some basic aspects of site-specific exploration and investigation. The governmental decision of 30th September and Nagra's two-phase investigation concept are then briefly considered. To close, the objectives of investigation phase I are outlined and possible results are briefly discussed. The research programme developed for investigation of the potential site at Oberbauenstock is presented in the second part of the report. Besides geological and hydrogeological investigations at the surface, the programme ...
Full text: Recent geoarchaeological research in the Erzurum district, north-eastern Anatolia, has revealed an abundance of obsidian at numerous neolithic and Bronze Age sites. Geochemical characterisation using neutron activation analysis indicates that the obsidian was obtained from several sources that are chemically distinct from the major sources already known from Central Anatolia an the Lake Van area. Multiple sources are represented in the samples collected from at least two of the sites, namely the sites of Sos and Pulur. The primary source of some of the obsidian utilised at the site of Sos has been located in the volcanic sequence outcropping tot he north-west of Pasinler. Field survey however has shown that the alluvial deposits along the main rivers and some of their tributaries were the main sources of the obsidian utilised at the sites near Erzurum. Trade or exchange ...
We describe a method for the analysis of multi-site phosphorylation in serine/threonine (Ser/Thr)-rich protein sequences. Site-specific mutagenesis was used to introduce tryptic cleavage sites in the serine glutamine/threonine glutamine cluster domain (SCD) of the human checkpoint protein kinase (Chk2). The mutant proteins were shown to autophosphorylate on residues that are inducibly phosphorylated when mammalian cells are exposed to ionizing radiation (serine 33/35, serine 516, threonine 68 and threonine 432). Five Ser/Thr clusters within the SCD were flanked by arginine or lysine residues to produce tryptic peptides for nanospray liquid chromatography (nanoLC)/linear quadrupole ion trap Fourier transform ion cyclotron resonance mass spectrometry. Phosphorylation sites were assigned usin...
The production of de-inked tailings in Quebec has significantly increased during the last decade. From less than 100,000 wet tons in 1990, the production of de-inked tailings reached 500,000 wet tons in 1995, and 510,000 wet tons in 1999. The geotechnical, hydraulic, and physico-chemical properties of de-inked tailings are favorable for its use as soil cover for the prevention of acid mine drainage at mining sites. In this presentation, the authors discussed the three-year monitoring of the behaviour of a membrane covering an old mining site with the potential to produce acid mine drainage. The site is located at the Clinton Mine, near Woburn, Quebec. The mine shaft was filled with the tailings and waste rock scattered around the site and covered with a protective membrane which included de-inked tailings. The profile of the membrane was discussed, as well as construction details. The results confirmed ...
The research has involved the characterization of catalyst acidity, [sup 2]D NMR studies of Bronsted acid sites, and kinetic, calorimetric, and spectroscopic studies of methylamine synthesis and related reactions over acid catalysts. Approach of this work was to explore quantitative correlations between factors that control the generation, type, strength, and catalytic properties of acid sites on zeolite catalysts. Microcalorimetry, thermogravimetric analysis, IR spectroscopy, and NMR spectroscopy have provided information about the nature and strength of acid sites in zeolites. This was vital in understanding the catalytic cycles involved in methylamine synthesis and related reactions over zeolite catalysts.
Unmanned systems are often used to augment the ability of humans to perform challenging tasks. While the value of individual unmanned vehicles have been proven for a variety of tasks, it is less understood how multiple unmanned systems should be used together to accomplish larger missions such as site security. The purpose of this paper is to discuss efforts by researchers at the Idaho National Laboratory (INL) to explore the utility and practicality of operating multiple unmanned systems for a site security mission. This paper reviews the technology developed for a multi-agent mission and summarizes the lessons-learned from a technology demonstration.
This paper describes the phenomenology of nuclear explosions and technologies for their detection as relevant to On-Site Inspection (OSI) for a comprehensive test-ban (CTB). Our experience with the US nuclear test program which has been primarily carried out at the Nevada Test Site (NTS) and in the Pacific Ocean. The goals of OSI are to resolve ambiguous events, reduce uncertainty, deter attempts at evasion, and provide responsive and technically competent means of confirming the occurrence of a nuclear explosion should deterrence fail. These goals would include finding evidence of an evasive nuclear explosion or evidence that the event was non-nuclear, such as an earthquake or large chemical explosion.
The purpose of the Ocean FUSRAP Program, which began in March 1981, is to assess the technical, environmental, and institutional feasibility of disposing, in the ocean and on the ocean floor, of FUSRAP waste which contains traces of natural radioactive materials. The initial planning has focused on the Middlesex, New Jersey, Sampling Plant site and surrounding properties, which contain on the order of 100,000 metric tons of material. The Belgian Congo uranium ore and other uranium ores used by the United States were handled at the sampling plant site and have since been removed.
The validation of the forecast model for early emergency response to nuclear accidents is evaluated by trace tests in atmosphere in Daya Bay nuclear power site. The simulation experiment of the Daya Bay nuclear power site shows that the particle spreading image and the time-integrated concentration distribution given by plume concentration prediction model can perform the variation of pathway of the pollutant transport, as well as the effects of topography on transport and diffusion of pollutants. The simulation of five trace tests in field shows that 59.1% of ratios between predicted results and observed results are within the range of 10, and 41% of ratios are within the range of 5 approximately. (authors)
Single Fe impurities were implanted in an Er single crystal and found to occupy both substitutional and interstitial sites, below a temperature of 200 K. The local susceptibility of Fe on both sites follows a Curie-Weiss law and exhibits a positive local Curie constant, indicating an antiferromagnetic coupling between the Fe and the surrounding Er moments. The corresponding nuclear spin relaxation rates follow a Korringa law as a function of temperature, confirming the dominance of local magnetism and the formation of local moments on each of the sites occupied by Fe.
Investigations were carried out of radiation level around Daya Bay for three times since the construction and operation Daya bay Nuclear Power Station and Lingao Nuclear Power Station in Guangdong province in the period of 1988 to 2000. As shown by the investigation, the radiation levels both in the field and indoors remains unchanged by and large but slightly higher than before on the roads. Also this paper gives the analysis of variations in radiation levels form site to site and from time to time. It was shown that, for environmental ? radiation levels measurements, typical measuring sites have significant impact on the meaning results. (authors)
'As part of the Computer Protection Plan, this Network Security Plan identifies the specific security measures used to protect Bechtel Hanford, Inc.'s (BHI's) enterprise network. The network consists of the communication infrastructure and information systems used by BHI to perform work related to the Environmental Restoration Contract (ERC) at the Hanford Site. It provides electronic communication between the ERC-leased facilities in Richland, Washington, and facilities located on the Hanford Site. Network gateways to other site and offsite networks provide electronic communication with the remainder of the Hanford community.'
The UFIP (French Petroleum Industry Association) studies concerning polluted sites and soils and their rehabilitation are presented: characterization of the admissible maximum fuel or gas oil content in the ground, the issue of time effects, and the risks it may induce for public health; study on the various pollutant impacts on the environment (underground waters, biotope...); approach to the development of a dynamical model describing these phenomena and their influence on man, in order to derive consistent and reasonable decontamination objectives